WCDMA Principles
Descrição do Produto
WCDMA RNP Fundamental www.huawei.com
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Objectives z
Upon completion of this course, you will be able to:
Get familiar with principles of radio wave propagation, and theoretically prepare for the subsequent link budget.
Introduce the knowledge about antennas and the meanings of typical indices.
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Page2
Contents 1. Radio Wave Introduction 2. Antenna 3. RF Basics 4. Symbol Explanation
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Contents 1. Radio Wave Introduction 1.1 Basic Principles of Radio Wave 1.2 Propagation Features of Radio Wave 1.3 Propagation Model of Radio Wave 1.4 Correction of Propagation Model
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Radio Wave Spectrum Frequency 3-30Hz 30-300Hz 300-3000Hz 3-30KHz 30-300KHz 300-3000KHz 3-30MHz 30-300MHz 300-3000MHz 3-30GHz 30-300GHz
Classification
Designation
Extremely Low Frequency Voice Frequency Very-low Frequency Low Frequency Medium Frequency High Frequency Very High Frequency Ultra High Frequency Super High Frequency Extremely High Frequency
ELF VF VLF LF MF HF VHF UHF SHF EHF
300-3000GHz The frequencies in each specific band present unique propagation features. Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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The radio waves are distributed in 3Hz ~ 3000GHz. This spectrum is divided into 12 bands, as shown in the above table. The frequencies in each specific band present unique propagation features: The lower the frequency is, the lower the propagation loss will be, the farther the coverage distance will be, and the stronger the diffraction capability will be. However, lower-band frequency resources are stringent and the system capacity is limited, so they are primarily applied to the systems of broadcast, television and paging. The higher-band frequency resources are abundant and the system capacity is large; however, the higher the frequency is, the higher the propagation loss will be, the shorter the coverage distance will be, and the weaker the diffraction capability will be. In addition, the higher the frequency is, the higher the technical difficulty will be, and the higher the system cost will be. The band for purpose of the mobile communication system should allow for both coverage effect and capacity. Compared with other bands, the UHF band achieves a good tradeoff between the coverage effect and the capacity, and is hence widely applied to the mobile communication field. Nevertheless, with the increase of mobile communication demand, more capacity is required. The mobile communication system is bound to develop toward the high-frequency band.
Propagation of Electromagnetic Wave z
When the radio wave propagates in the air, the electric field direction changes regularly. If the electric field direction of radio wave is vertical to the ground, the radio wave is vertical polarization wave
If the electric field direction of radio wave is parallel with the ground, the radio wave is horizontal polarization wave
Dipole Magnetic Field
Magnetic Field Electric Field
Electric Field
Electric Field
electric wave transmission direction
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Propagation of electromagnetic propagation takes on an energy propagation mode. During the propagation, the electric field is vertical to the magnetic field, both vertical to the propagation direction. Through interaction between the electric field and the magnetic field, the energy is propagated to the distance, just like propagation of water waves.
Propagation Path
Perpendicular incidence wave and ground refraction wave (most common propagation modes)
Troposphere reflection wave (the propagation is very random)
Mountain diffraction wave (shadow area signal source) Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Ionosphere refraction wave (beyond-the-horizon communication path)
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Radio wave can be propagated from the transmitting antenna to the receiving antenna in many ways: perpendicular incidence wave or ground refraction wave, diffraction wave, troposphere reflection wave, ionosphere reflection wave, as shown in the diagram. As for radio wave, the most simple propagation mode between the transmitter and the receiver is free space propagation. One is perpendicular incidence wave; the other is ground reflection wave. The result of overlaying the perpendicular incidence wave and the reflection wave may strengthen the signal, or weaken the signal, which is known as multi-path effect. Diffraction wave is the main radio wave signal source for shadow areas such building interior. The strength of the diffraction wave is much dependent of the propagation environment. The higher the frequency is, the weaker the diffraction signal will be. The troposphere reflection wave derives from the troposphere. The heterogeneous media in the troposphere changes from time to time for weather reasons. Its reflectance decreases with the increase of height. This slowly changing reflectance causes the radio wave to curve. The troposphere mode is applicable to the wireless communication where the wavelength is less than 10m (i.e., frequency is greater than 30MHz).Ionosphere reflection propagation: When the wavelength of the radio wave is less than 1m (frequency is greater than 300MHz), the ionosphere is the reflector. There may be one or multiple hops in the radio wave reflected from the ionosphere, so this propagation is applicable to long-distance communication. Like the troposphere, the ionosphere also presents the continuous fluctuation feature.
Propagation Path
① ② ③ ④ Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Building reflection wave Diffraction wave Direct wave Ground reflection wave Page8
In a typical cellular mobile communication environment, a mobile station is always far shorter than a BTS. The direct path between the transmitter and the receiver is blocked by buildings or other objects. Therefore, the communication between the cellular BTS and the mobile station is performed via many other paths than the direct path. In the UHF band, the electromagnetic wave from the transmitter to the receiver is primarily propagated by means of scattering, namely, the electromagnetic wave is reflected from the building plane or refracted from the man-made or natural objects.
Contents 1. Radio Wave Introduction 1.1 Basic Principles of Radio Wave 1.2 Propagation Features of Radio Wave 1.3 Propagation Model of Radio Wave 1.4 Correction of Propagation Model
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Radio Propagation Environment z
Radio wave propagation is affected by topographic structure and man-made environment. The radio propagation environment directly decides the selection of propagation models. Main factors that affect environment are:
Natural landform (mountain, hill, plains, water area)
Quantity, layout and material features of man-made buildings
Natural and man-made electromagnetic noise conditions
Weather conditions
Vegetation features of the region
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The radio wave is largely affected by the topography and man-made environment. The natural landforms such as mountains and hills as well as man-made buildings affect the propagation features of radio waves. Weather and time conditions also affect propagation of radio wave. For example, the ionosphere is relatively stable at night, so the shortwave radio is well received.
Landform Categories Quasi-smooth landform
T R
The landform with a slightly rugged surface and the surface height difference is less than 20m
Irregular landform The landforms apart from quasi-smooth landform
T
are divided to: hill landform, isolated hills, slant
R
landform, and land & water combined landform
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The quasi-smooth landform refers to the landform with a slightly rugged surface, and the surface height difference is less than 20m. The average surface height difference is slight. The Okumura propagation model defines the roughness height as the difference between 10% and 90% of the landform roughness in 10km in front of the mobile station antenna. CCIR defines it as the difference between the height over 90% and the height over 10% of landform height at 10~50 km in front of the receiver. Other landforms than abovementioned are called “irregular landforms”.
Signal Fading Receiving power (dBm)
-20
fast fading slow fading
-40
-60
10
20
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30
distance (m) Page12
Slow fading: In case shadow effect is caused by obstacles, and the receiving signal strength decreases but the field strength mid-value changes slowly with the change of the topography, the strength decrease is called “slow fading” or “shadow fading”. The field strength mid-value of slow fading takes on a logarithmic normal distribution, and is related to location/locale. The fading speed is dependent on the speed of the mobile station. Fast fading: In case the amplitude and phase of the combined wave change sharply with the motion of the mobile station, the change is called “fast fading”. The spatial distribution of deep fading points is similar to interval of half of wavelength. Since its field strength takes on Rayleigh distribution, the fading is also called Rayleigh fading. The amplitude, phase and angle of the fading are random. Fast fading is subdivided into the following three categories: Time-selective fading: In case the user moves quickly and causes Doppler effect on the frequency domain, and thus results in frequency diffusion, timeselective fading will occur. Space-selective fading: The fading features vary between different places and different transmission paths. Frequency-selective fading: The fading features vary between different frequencies, which results in delay diffusion and frequency-selective fading.
In order to mitigate the influence of fast fading on wireless communication, typical methods are: space diversity, frequency diversity, and time diversity.
Signal Diversity Measures against fast fading --- Diversity z
Time diversity
z
Space diversity
z
Frequency diversity
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To resist such kind of fast fading, the BTS adopts the time diversify, space diversity (polarization diversity), and frequency diversity. Time diversity uses the methods of symbol interleaving, error check and error correction code. Each code has different anti-fading features. Space diversity uses the main/diversity antenna receiving. The BTS receiver handles the signals received by the main and diversity antennas respectively, typically in a maximum likelihood method. This main/diversity receiving effect is guaranteed by the irrelevance of main antenna receiving and diversity antenna receiving. Here “irrelevance” means the signals received by the main antenna and the signals received by the diversity antenna do not have the feature of simultaneous attenuation. This requires the interval between the main antenna and the diversity antenna in case of space diversity to be greater than 10 times of the radio signal wavelength (for GSM, the antenna interval should be greater than 4m in a distance of 900m, and greater than 2m in a distance of 1800m). Alternatively, the polarization diversity method should be used to ensure that signals received by the main and diversity antennas do not have the same attenuation features. As for mobile stations (mobile phones), only one antenna exists, so this space diversity function is not supported. The BTS receiver’s capability of balancing the signals of different delays in a certain time range (time window) is also a mode of space diversity. In case of soft switch in the CDMA communication, the mobile station contacts multiple BTSs concurrently,
and selects the best signals from them, which is also a mode of space diversity. Frequency diversity is performed primarily by means of spreading. In the GSM communication, it simply uses the frequency hopping to obtain the frequency hop gain; in the CDMA communication, since every channel works at a broad band (WCDMA has a band of 5MHz), the communication itself is a kind of spreading communication.
Radio Wave Delay Extension z
Deriving from reflection, it refers to the co-frequency interference caused by the time difference in the space transmission of main signals and other multi-path signals received by the receiver
z
The transmitting signals come from the objects far away from the receiving antenna Solution
RAKE RAKEtechnology technology
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Radio wave delay extension—Another type of frequency-selective fading. The spatial distribution of deep fading points is similar to interval of half of a wavelength (17cm for 900MHz, 8cm for 1800/1900MHz). If the mobile station antenna is located at this deep fading point at this time (when the mobile user in a car resides in this deep fading point in case of a red light, we call it “read light problem”), the voice quality is very poor, and relevant technologies should be used to resolve it, e.g., the Rake technology in CDMA system.
Diffraction Loss z
The electromagnetic wave diffuses around at the diffraction point
z
The diffraction wave covers all directions except the obstacle
z
The diffusion loss is most severe
T R
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When analyzing the transmission loss in the mountains or the built-up downtowns, we usually need to analyze the diffraction loss and penetration loss. Diffraction loss is a measure for the obstacle height and the antenna height. The obstacle height must be compared with the propagation wavelength. The diffraction loss generated by the height of the same obstacle for the long wavelength is less than that for short wavelength. Diffraction loss is caused the electromagnetic wave being scattered around at the diffraction point, and the diffraction wave covers all directions except the obstacle. This diffusion loss is most severe, and the calculation formula is complicated and varies with different diffraction constants.
Penetration Loss z
Penetration loss caused by obstructions:
WdBm
XdBm
Penetration Penetrationloss loss=X-W=B =X-W=BdB dB Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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Indoor penetration loss refers to the difference between the average signal strength outside the building and the average signal strength of one layer of the building. Penetration loss represents the capability of the signal penetrating the building. The buildings of different structures affect the signals significantly. The penetration loss generated by the long wavelength is greater than that generated by the short wavelength of the same building. The incidence angle of the electromagnetic wave also affects the penetration loss considerably. Typical Penetration loss: z
Wall obstruction : 5~20dB
z
Floor obstruction : >20dB
z
Indoor loss value is the function of the floor number : -1.9dB/floor
z
Obstruction of furniture and other obstacles: 2~15dB
z
Thick glass : 6~10dB
z
Penetration loss of train carriage is ：15~30dB
z
Penetration loss of lift is : 30dB
z
Dense tree leaves loss : 10dB
Contents 1. Radio Wave Introduction 1.1 Basic Principles of Radio Wave 1.2 Propagation Features of Radio Wave 1.3 Propagation Model of Radio Wave 1.4 Correction of Propagation Model
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Propagation model z
Propagation model is used for predicting the medium value of path loss. The formula can be simplified under if the heights of UE and base station are given
PathLoss = f (d , f )
where: d is the distance between UE and base station, and frequency z
f
is the
Propagation environment affect the model, and the main factors are :
Natural terrain, such as mountain, hill, plain, water land, etc…;
Man-made building (height, distribution and material);
Vegetation;
Weather;
External noise
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If the heights of UE and BTS are given and ignore the environment affect, the path loss is just related with the distance between UE and BTS and radio frequency.
Free Air Space Model
Lo=91.48+20lgd, for f=900MHz Lo=97.98+20lgd, for f=1900MHz z
Free space propagation model is applicable to the wireless environment with isotropic propagation media (e.g., vacuum), and is a theoretic model
z
This environment does not exist in real life
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Free space means an infinite space full of even, linear, isotropic ideal media, and is an ideal situation. For example, the radio wave propagation of satellite is very similar to the propagation condition of free space. As seen from the above formula, once the distance is doubled, the loss will increase by 6dB. If the frequency is doubled, as shown in the above example, the 1900MHz loss will be 6dB more than the 900MHz loss.
Flat Landform Propagation Model Ploss = L0+10χlgd -20lghb - 20lghm χ ： Path loss gradient , usually is 4
T
hb： BTS antenna height hm：mobile station height
R
L0：parameters related to frequency
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Page22
In the flat landform propagation model, in addition to the frequency and distance, we also consider the heights of the UE and BTS. Once the BTS antenna height is doubled, the path loss will be compensated for by 6dB.
Okumura-Hata Model Application Scope z
Frequency range
f:150~1500MHz
z
BTS antenna height
Hb:30~200m
z
Mobile station height Hm:1~10m
z
Distance
d:1~20km
Characteristic z z z z
Macro cell model The BTS antenna is taller than the surrounding buildings Predication is not applicable in 1km Not applicable to the circumstance where the frequency is above 1500MHz
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The Okumura-Hata model is commonly used in the planning software. It is applicable to the micro cell that covers more than 1km below 1500MHz. In 1960s, Okumura and his men used a broad range of frequencies, heights of several fixed stations and heights of several mobile stations to measure the signal strength in all kinds of irregular landforms and environments, and developed a series of curves, then set up a model by fitting the curves to obtain the empiric formula of propagation model. This model has been widely used across the globe, and is applicable to areas outside Tokyo by use of the correction factor.
COST 231-Hata Model Application Scope z
Frequency range
f:1505~2000MHz
z
BTS antenna height
Hb:30~200m
z
Mobile station height Hm:1~10m
z
Distance
d:1~20km
Characteristic z z z z
Macro cell model The BTS antenna is taller than the surrounding buildings Predication is not applicable in 1km Not applicable to the circumstance where the frequency is above 2000MHz or below 1500MHz
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The COST231 model is applicable 1500-2000MHz, and is not accurate within 1km. The COST231-hata model is based on the test results of Okumura, and works out the suggested formula by analyzing the propagation curve of higher bands.
COST 231 Walfish-Ikegami Model Application Scope z
Frequency range :
800~2000MHz
z
BTS antenna height Hbase :
z
Mobile station height Hmobile : 1~3m
z
Distance d :
4~50m
0.02~5km
Characteristic
z
Urban environment, macro cell or micro cell
z
Not applicable to suburban or rural environment
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The COST231 propagation model team of the European Research Committee puts forward the following two suggested models: One is based on the Hata model, and works out the frequency coverage extends from 1500MHz to 2000MHz by using some correction items. However, in all the test environments, the BTS is taller than the surrounding buildings, so it is not appropriate to extend the valid range to the circumstance where the BTS antenna is lower than the surrounding buildings. This model is applicable to “large-cell macro cell”. In the “micro cell”, the BTS antenna is lower than the roof, so the Committee created the “COST-Walfish-Ikegami” model according to the results of Walfish’s calculation of the urban environment, the Ikegami’s corrective function for handling the street direction and the test data. This model is tested in a German city Mannheim, and more improvements are found to be made. When using the model, some parameters that describe the urban environment features may be required: Building height Hroof (m) Pavement width w (m) Building interval b (m) Street direction against the perpendicular incidence wave direction α ( ° )
Standard Propagation Experimental formula
PathLoss = K1 + K 2 log(D ) + K 3 log(H Txeff ) + K 4 × Diffraction loss
+ K 5 log(D ) × log(H Txeff ) + K 6 (H Rxeff ) + K clutter f (clutter ) Explanation K1: K2: D: K3: HTxeff: K4: K5: K6:
Propagation path loss constant value log(d) correction factor Distance between receiver and transmitter (m) log(HTxeff) correction factor Transmitter antenna height (m) Diffraction loss correction factor log(HTxeff)log(D) correction factor Correction factor H Rxeff : Receiver antenna height (m) Kclutter: clutter correction factor
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Page26
Using the multiplier factor configured by customer, the propagation model can be made by order totally. It can support using different K1 and K2 according to distance and LOS or NLOS. It also can use different diffraction loss algorithm and effective BTS height algorithm. One optional amendment condition is that U-net can amend the path loss of hilly terrains environments under it is LOS between transmitter and receiver.
Contents 1. Radio Wave Introduction 1.1 Basic Principles of Radio Wave 1.2 Propagation Features of Radio Wave 1.3 Propagation Model of Radio Wave 1.4 Correction of Propagation Model
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Basic Principles and Procedures Target propagation environment
Selected propagated environment
CW data collection
parameter setting
Measured propagation path loss
Forecast propagation path loss
Comparison
Error compliant with requirements?
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Page28
Due to difference of propagation environment, the propagation model parameters must be corrected based on measured values, so as to embody the radio wave propagation features of the actual environment. Generally, we use the Continuous Wave (CW) test method to measure the propagation path loss in the actual environment. By comparing the actual value with the forecast value, we adjust the parameters in the model. The process recurs until the error meets the requirements.
Site Selection Criteria for selecting a site
The antenna height is greater than 20m
The antenna is at least 5m taller than the nearest obstacle
5m
z
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Page29
If the antenna is taller than the nearest obstacle by 5m or more, the data in GSM will be inherited, as defined according to the first Fresnel zone. This condition is sufficiently compliant with the WCDMA requirements. “Obstacle” here means the tallest building on the roof of the antenna. The building serving as a site should be taller than the average height of the surrounding buildings
Test Platform z
Transmitting subsystems
Transmitting antenna, feeder, high-frequency signal source, antenna bracket Antenna
OmniAntenna
bracket
Feeder
Transmitter Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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After the test platform is set up, switch on the signal source to transmit the RF signal, and begin drive test. To perform the CW test, it is necessary to select an appropriate site for transmitting the RF signal. In case of CW test data handling, it is necessary to be aware of the EIRP of the test BTS, and record the data of signal gain attributable to each part, including signal source transmitting power, RF cable loss, transmitting antenna gain, and receiving antenna gain.
Test Platform z
Receiving subsystem
Test receiver, GPS receiver, test software, portable
GPS-Antenna
Antenna
Positioning Receiver System
Data Acquisition System
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Page31
After the test platform is set up, switch on the signal source to transmit the RF signal, and begin drive test. To perform the CW test, it is necessary to select an appropriate site for transmitting the RF signal.In case of CW test data handling, it is necessary to be aware of the EIRP of the test BTS, and record the data of signal gain attributable to each part, including signal source transmitting power, RF cable loss, transmitting antenna gain, and receiving antenna gain.
Test Path z
Rules of selecting a test path
Landform: the test path must consider all main landforms in the region. Height: If the landform is very rugged, the test path must consider the landforms of different heights in the region. Distance: The test path must consider the positions differently away from the site in the region. Direction: The test points on the lengthways path must be identical with that on the widthways path. Length: The total length of the distance in one CW test should be greater than 60km. Number of test points: The more the test points are, the better (>10000 points, >4 hours as a minimum)
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Page32
The distance corrected in the CW test primarily falls within the impact range of this cell, so the test distance is not necessarily more than twice of the cell radius. The total length of the test distance in a CW test should be greater than 60km.Generally, the number of test points for each site is more than 10000, or the test duration is more than 4 hours. According to the sampling rate of 1 point/6m after smoothing the sampling data, it takes at least 60km as a test distance for 10000 sampling points.
Test Path z
Rules of selecting a test path
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Overlaying: The test path of different test sites can be preferably overlapped to increase the reliability of the model Obstacles: When the antenna signals are obstructed by one side of the building, do not run to the shadow area behind this side of building
Drive Test z
The sampling law is meets the Richard Law :40 wavelengths, 50 sampling points
z
Upper limit of drive speed: Vmax=0.8λ/Tsample
z
The test results obtained in exceptional circumstances must be removed from the sampling data
z
Sampling point with too high fading (more than 30dB) ;
In a tunnel
Under a viaduct
If using a directional antenna for CW test, the test path is selected from the main lobe coverage area
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Sampling distance: The distance between adjacent sampling points should be λ-λ/4 so as to eliminate the impact of Raylaigh fading. Suppose the sampling frequency of the drive test equipment is: 1000HzThe 2G band bearer wavelength is: 0.15m (50 sampling points are required per 6m)Upper limit of drive speed: 0.8*0.15*1000=120m/s
Test Data Processing z
The test data needs to be processed before being able to be identified by the planning software. The processing procedure is:
Data filtering
Data dispersion
Geographic averaging
Format conversion
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Page35
The CW test data obtained after reasonable design are basis of our model correction, and are input of the first step. The reasonableness of the CW test data directly affects the correctness of the correction result. However, even the design is reasonable, the measured data is not perfect, and needs further processing. Typical processing steps include: Data filtering, data dispersion, geographical averaging, and format conversion. In the actual test, some test data may be inconsistent with the model correction requirements. In order to avoid such data from affecting the model correction result adversely, such data should be filtered. 1. Since we need to know the accurate position of each test point in the model correction, for the data obtained from measuring the places where GPS cannot position accurately should be filtered. Such circumstances include: 1) under a viaduct; 2) in a tunnel; 3) in the narrow street with tall buildings on both sides; 4) in the narrow street covered by dense tree leaves. 2. Generally, we regard the distance 0.1R~2R away from the antenna is reasonable, where R is the forecast cell radius. The signal strength distribution and the propagation distance do not form a strict linear relationship. If too near, the test data will be less, and average distribution will be impossible. 3. If the receiving signal is too weak, exceptional value point may occur, because the receiver is located at the critical status of resolving the signal at this time, and its value is vulnerable to influence of transient fluctuation. To prevent the deeply faded signals from being filtered, we use the homocentric circle technology to filter out circular rings at the test point lower than-121dbm, e.g., above 20% of the site ring. That is because the
receiver speed is far greater than the GPS signal collection speed, and will result in multiple test data at one location point. Suppose the vehicle runs at equal speeds, such data should be distributed to the two fixed points on average, which is a process of data dispersion. The main function of geographic averaging is to eliminate the influence of fast fading and slow fading.
Contents 1. Radio Wave Introduction 2. Antenna 3. RF Basics 4. Symbol Explanation
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Positions and Functions of Antenna BTS antenna & feeder system diagram Antenna adjustment bracket radio mast (φ50~114mm) 3-connector seal component insulation sealing tape, PVC insulation tape GSM/CDMA plate-shape antenna
Grounding device main (7/8“)
feeder Indoor super flexible feeder
Outdoor feeder Cabling rack
Feeder clip
Lightning protection device Feeder cabling window
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main device of BTS Page38
Positions and functions of antenna: In the radio communication system, antenna is an interface between the transceiver and the outside communication media. An antenna may both emit and receive radio waves; it converts the high-frequency current to electromagnetic wave when transmitting; and converts the electromagnetic wave to high-frequency current when receiving. Other parts of the antenna & feeder are shown in the diagram.
Working Principles of Mobile Antenna Dipole Dipole Feed network
Feed network Feed network
Antenna Connector
Directional antenna
Antenna Connector
omni antenna
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Page39
The BTS antenna in mobile communication system is antenna array consist of a lot of basic dipole units. The dipole unit is half wave dipole that the length of dipole is half wave of electromagnetic wave. The feed network usually use equal power network. For directional antenna, there is a metal flat at the back of dipole units as a reflection plane to increase the antenna gain. The tie-in of antenna usually is DIN type (7/16''). Usually it is at the bottom of antenna, sometimes at the back of antenna. Structurally, the dipole units and feed network are covered by antenna casing to protect the antenna. Usually, the antenna casing is made by PVC material or tempered glass, and the loss for electromagnetic wave is less and the strength is better.
Categories of Antenna Categorize by emission direction
Directional antenna Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
omni antenna Page40
By emission direction, antennas are categorized into directional antenna and omni antenna. Directional antenna usually is used in urban area, and omni antenna is used in rural area for wide coverage.
Categories of Antenna Categorize by appearance
Plate-shape antenna
Cap-shape antenna
Whip-shape Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Paraboloid antenna Page41
The installed antennas can be categorized into plate-shape antenna, cap-shape antenna, whip-shape, and paraboloid antenna. As shown in the above diagram, the cap-shape antenna is generally used in indoor distribution system, while the paraboloid antenna is mainly used for satellite communication and radar.
Categories of Antenna Categorize by polarization mode
Omni antenna
Uni-polarization Directional antenna
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Dual polarization Directional antenna Page42
By polarization mode, antennas are categorized into: vertical polarization antenna (or unipolarization antenna), cross polarization antenna (or dual polarization antenna). The foregoing two polarization modes are both line polarization mode. Circle polarization and oval antenna are usually not used in GSM. Unipolarization antennas are mostly vertical polarization antennas. The polarization direction of their dipole unit is in the vertical direction. Dual polarization antennas are mostly 45-degree slant polarization antennas. Their dipole unit is a dipole that crosses the leftward tilt 45-degree polarization and rightward tilt 45-degree polarization, as shown in the above diagram. The dual polarization antennas are equivalent to two unipolarization antennas combined into one. Use of dual polarization antennas can reduce the number of antennas on the tower, and reduce the workload of installation, hence reduces the system cost, so they are popularly applied now.
Categories of Antenna Smart antenna
Smart directional antenna
Smart directional antenna
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Smart omni-antenna
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Smart antenna techniques are already used in many wireless systems, but UMTS is the first system where they are considered already in the system specification phase. Smart antennas are especially attractive in WCDMA networks, as they could be used to reduce the intracell interference levels considerably. Interference is one of the most important and difficult issues in the WCDMA air interface, and any improvement in the interference level management will bring increased capacity. Generally, a smart antenna is an antenna structure consisting of more than one physical antenna element, and a signal processing unit that controls these elements and combines or distributes the signals among these elements. Note that the antenna elements are not smart as such, but the smartness of the device lies in the controlling signal processing unit.
Categories of Antenna Electric down tilt Antenna
Electrical down tilt Antenna Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
The main parts of electric down tilt antenna: 1. RCU (Remote Control Unit) 2. SBT (Smart Bias-Tee) 3. BT (Bias-Tee) 4. STMA (Smart TMA)
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Electric Indices of Antenna
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Electric performances include: working band, gain, polarization mode, lobe width, preset tilt angle, down tilt mode, down tilt angle adjustment range, front and back suppression ratios, side lobe suppression ratio, zero point filling, echo loss, power capacity, impedance, third order inter-modulation.
Antenna Direction Diagram Symmetric halfhalf-wave dipole
side view
Top view
omni antenna direction diagram
directional antenna direction diagram
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Page46
Direction ability of antenna refers to the capability of the antenna emitting electromagnetic waves toward a certain direction. For a receiving antenna, the direction ability means the capability of the antenna receiving radio waves from different directions. The characteristic curve of direction ability of antenna is generally represented in a direction diagram. Direction diagram is used for describing the capability of the antenna receiving/emitting electromagnetic waves in different directions of the air.
Antenna Gain
2.15dB
dBi与dBd
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Page47
Gain means a ratio of the power density generated by the antenna at a certain point in the maximum emission direction to the power density generated by the ideal point source antenna at the same point. Gain reflects the capability of the antenna emitting the radio waves in a certain direction in a centralized way. Generally, the higher of the antenna gain is, the narrower the lobe width will be, and more centralized the energy emitted by the antenna will be. The unit of antenna gain is dBi or dBd. dBi uses the ideal point source antenna gain as a reference, and dBd uses the half-wave dipole antenna gain as a reference. The difference of values represented by the two kinds of unit is 2.15 dB. For example, if the antenna gain is 11dBi, it can be said as 8.85dBd, as shown in the above diagram. dBi is defined as the energy centralization capability of the actual direction antenna (including omni antenna) relative to the isotropic antenna, where “i” represents “Isotropic”.dBd is defined as the energy centralization capability of the actual direction antenna (including omni antenna) relative to the half-wave dipole antenna, where “d” represents “Dipole”.
Antenna Pattern
Antenna pattern Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page48
It is a three-dimensional solid pattern. It show the theoretic pattern of one directional antenna.
Antenna Pattern
Side lobe Zero point Back
Main lobe filling
lobe Max value
horizontal half-
Front to
power angles
back Zero point
ratio
filling
Vertical pattern
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Horizontal pattern
Page49
Beam width is one of the key indices of antenna. It consists of horizontal halfpower angle and vertical half-power angle. Horizontal half-power angle/vertical half-power angle is defined as beam width between the two points where the power is reduced by half (3dB) in the horizontal/vertical directional relative to the maximum emission direction. Typical horizontal half-power angles of BTS antenna are 360°, 210°, 120°, 90°, 65°, 60°, 45° and 33°. Typical vertical half-power angles of BTS antenna are 6.5°, 13°, 25° and 78°. The front/back suppression ratio means the ratio of signal emission strength of the antenna in the main lobe direction and in the side lobe direction, and the difference between the side lobe level and the maximum beam within backward 180°±30°. Generally, the front/back ratio of antenna falls within 18~45dB. For dense urban areas, the antenna with great front/back suppression ratio is preferred. Zero point filling: When the BTS antenna vertical plane adopts the shaped-beam design, in order to make the emission level in the service are more even, the first zero point of the lower side lobe should be filled, rather than leaving an obvious zero depth. High-gain antennas have narrow vertical half-power angles, so especially need the zero point filling technology to improve the nearby coverage. Generally, if the zero depth is -26dB greater than the main beam, it indicates that the antenna has zero point filling. Some suppliers adopt percentage notation. For example, when an antenna zero point filling is 10%. The relationship between the
two notation methods is: Y dB=20log(X%/100%) For example, zero point filling 10%, namely, X=10; using dB to notate it: Y=20log(10%/100%)=-20dBUpper side lobe suppression: For the cellular system based on minor cell system, in order to improve the frequency multiplexing and reduce the co-frequency interference between adjacent cells, the BTS antenna lobe shaping should lower the side lobe aimed at the interference area, and increase the D/U value. The first side lobe level should be less than –18dB. For the BTS antenna based on major cell system, this requirement is not imposed.
Mechanical Down Tilt and Electric Down Tilt Mechanical down tilt
Electric down tilt
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Page51
Three kinds of methods and their combinations are usually used for antenna beam downtilt: Mechanical downtilt, preset electricity downtilt and electrically controlled downtilt (for electrically controlled antennas). During adjustment of the electrically controlled antenna downtilt angle, the antenna itself will not move, but the phase of the antenna dipole is adjusted through electricity signals to change the field intensity so that the antenna emission energy deviates from the zero-degree direction. The filed intensity of the antenna is increased or decreased in each direction so that there will be little change in the antenna pattern after the downtilt angle is changed. The horizontal semi-power width is unrelated with the downtilt angle. However, during mechanical adjustment of the downtilt angle, the antenna itself will be moved. It is necessary to change the downtilt angle by adjusting the location of the back support of the antenna. When the downtilt angle is very large, although the coverage distance in the main lobe direction changes obviously, yet signals in the direction perpendicular to the main lobe almost keep not change, the antenna pattern deforms seriously, and the horizontal beam width becomes greater as the downtilt angle is increased. A preset downtilt antenna is similar to an electrically controlled antenna in working principle, but a preset angle can not be adjusted.
The advantages of an electrically controlled antenna are as follows: When the downtilt angle is very large, the coverage distance in the main lobe direction will be shortened obviously and the antenna pattern will not remarkably change, so the interference can be reduced. On the other hand, mechanical downtilt may deform the pattern. The larger the angle is, the more serious the deformation is. Hence it is difficult to control the interference. In addition, electrically controlled downtilt and the mechanical downtilt have different influence on the back lobe. Electrically controlled downtilt allows further control of the influence on the back lobe, while mechanical downtilt enlarges the influence on the back lobe. If the mechanical downtilt angle is very large, the emission signals of the antenna will propagate to high buildings in backward direction through the back lobe, thus resulting in additional interference. In addition, during network optimization, management and maintenance, when we need to adjust the downtilt angle of an electrically controlled antenna, it is unnecessary to shut down the entire system. So we can monitor the adjustment of the antenna downtilt angle using special test equipment for mobile communication, so as to ensure the optimum value of the downtilt angle value of the antenna.
Contents 1. Radio Wave Introduction 2. Antenna 3. RF Basics 4. Symbol Explanation
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Page53
Introduction to Power Unit z
Absolute power(dBm) The absolute power of RF signals is notated by dBm and dBW. Their conversion relationships with mW and W are: e.g., the signal power is x W, its size notated by dBm is:
⎛ PW *1000 mw ⎞ p ( dBm ) = 10 lg⎜ ⎟ 1mw ⎝ ⎠ For example, 1W=30dBm=0dBW. z
⎛ P mw p ( dB ) = 10 lg ⎜⎜ 1 ⎝ P 2 mW
⎞ ⎟⎟ ⎠
Relative power(dB) It is the logarithmic notation of the ratio of any two powers For example：If P1 = 2w , P2 = 1w so P1 is 3dB greater than P2
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page54
Most spectrum analyzers use the dB notation to display the measurement results. dB is so popularly used because it can use the logarithmic mode to compress the signal level that changes in a wide range. For example, 1V signal and 10uV signal can appear on the monitor whose dynamic range is 100dB, while the linear scale cannot display the two signals simultaneously in a clear picture. Therefore, dB is determines the power ratio and voltage ratio in the logarithmic mode. In this case, the multiplication operation changes to convenient addition operation. It is typically used in calculating the gain and loss in the electronic systems.
Noise-Related Concepts z
Noise
z
Noise means the unpredictable interference signal that occur during the signal processing (the point frequency interference is not counted as noise)
Noise figure
Noise figure is used for measuring the processing capability of the RF component for small signals, and is usually defined as: output SNR divided by unit input SNR
Si NF
Ni So No
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Page55
Typical noises are: external sky and electric noise, vehicle start-up noise, heat noise from inside systems, scattered noise of transistor during operation, intermodulation product of signal and noise.
Noise-Related Concepts z
Noise figure formula of cascaded network
G1 NF1
NFtotal = NF 1 +
G2 NF2
Gn NFn
NF 2 − 1 NFn − 1 + ... + G1 G1 ⋅ G 2 ⋅ ... ⋅ Gn − 1
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Page56
As seen from the above formula, in the system noise, the noise figure of the level-1 component imposes the greatest influence, the noise figure of level-2 component imposes less influence, and so on. This explains why the cascaded noise figure is reduced after installing the tower amplifier. Usually, the NF of TMA is 1.5 . The NF of the level-1 component of BTS is 2.2 .
Receiving Sensitivity z
Receiving sensitivity Expressed with power:
Smin=10log(KTB)+ Ft (NF) +(S/N), unit: dBm K is a Boltzmann constant, unit: J/K (joule /K) , K=1.38066*10-19 J/K T represents absolute temperature, unit: °K B represents signal bandwidth, unit: Hz Ft represents noise figure, unit: dB (S/N) represents required signal-to-noise ratio, unit: dB If B=1Hz, 10log(KTB)=-174dBm/Hz
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Page57
Receiving sensitivity refers to the minimum receiving signal strength under a certain signal-to-noise ratio. It is an index that reflects the receiving capability of the equipment.
RF Components z
Tower Mounted Amplifier
Enlarge uplink signal, but it’s a loss for downlink
z
Duplexer
Sharing antenna for receiving and transmitting
Sharing antenna for multi-system
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page58
The core of a TMA is a low noise amplifier, which can be used to solve a limited uplink coverage problem and increase the uplink coverage area. For uplink, the gain is around 13dB. For downlink, the loss is around 0.3dB. Duplexer : A device that permits the simultaneous use of a transmitter and a receiver in connection with a common element such as an antenna system.
RF Components z
Splitter
z
Coupler
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Page59
Both couplers and power splitters are components for power distribution. The difference is: a power splitter is for equal power distribution, while a coupler is for non-equal power distribution. Therefore, couplers and power splitters are used in different applications. In general, to distribute power to different antennas within the same storey, a power splitter is used; to distribute power from the trunk to tributaries of different stories, a coupler is used. If couplers and power splitters are used in coordination, the transmit power of the signal source can be distributed as evenly as possible to various antenna ports of the system, namely, the transmit power of each antenna in the entire distribution system is almost the same. During power splitter selection, priority should be given to 1/2 power splitters, not 1/4 power splitters. When using a 1/3 power splitter, make sure that the power splitter is not too close to the antenna, and the feeder cable connecting them should be over 20m long.
Distribution System Splitter
Coupler
Splitter
Trunk
Trunk Splitter
Trunk
Coupler
Splitter Splitter
Tx/Rx
Splitter
Coupler
Splitter
Splitter Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page60
In the tunnel/subway/indoor, if we cover it just by outdoor NodeBs, because of the blocking of the obstacle, the QoS will be very bad, even cause call drop. In addition, in large building, we usually use micro cell system to cover it. But the indoor environment is different with outdoor and it is hard to use one fixed antenna to cover the whole building because of the blocking of the wall and other obstacle. The indoor distribution system (IDS) can solve these problems and increase the coverage of the micro NodeB. So the IDS is necessary in some buildings. In general, when selecting feeder cable types, select 7/8" cable for the trunk, and 1/2" common cables or super flexible cable for tributaries. During the trunk cabling process, if the curvature radius does not meet the requirement, the trunk can be disconnected at corners, and a section of 1/2" super flexible cable can be used for cabling around the corners.
Contents 1. Radio Wave Introduction 2. Antenna 3. RF Basics 4. Symbol Explanation
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Page61
Symbol Explanation z
Ec
Average energy per Chip
Not considered individually, but used for Ec/Io
Pilot Ec is measured by the UE (for HO) or the Pilot scanner, in the form of Received Signal Code Power (RSCP) For CPICH Ec:
Depends on power and path loss. Constant for a given power and path loss. Ec is not dependent on load
For DPCH Ec:
Depends on power and path loss
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Page62
The same could be said for the Dedicated Channel as for the pilot. The Ec remains constant for a given power and path loss. The main difference between the pilot and the DCH is that the DCH is power controlled.
Symbol Explanation z
Eb
Average energy per information bit for the PCCPCH, SCCPCH, and DPCH, at the UE antenna connector. Typically not considered individually, but used for Eb/Nt Depends on channel power (can be variable), path loss, and spreading gain (Gp)
Constant for a given bit rate, channel power, and path loss
Can be estimated form Ec and processing gain
Speech 12.2kbps example
Ec = -80 dBm
12.2kbps data rate => Processing gain = 24.98 dB
Eb~ -80 + 24.98 = -55.02 dBm
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Page63
Symbol Explanation z
Io
The total received power spectral density, including signal and interference, as measured at the UE antenna connector. Similar to UTRA carrier Receive Strength Signal Indicator (RSSI), at least for practical consideration (SC scanner)
RSSI in W or dBm
Io in W/Hz or dBm/Hz
Measured by the UE (for HO) or Pilot scanner in the form of RSSI
Depends on All channel power, All cells, and path loss
Depends on same-cell and other cell loading
Depends on external interferences
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Page64
This is different form other Io definitions: other users’ interferences Io = total receive power – per-channel receive power This latest definition of Io is more in line with the ISCP (Interference Signal Code Power) defined in the standard
Symbol Explanation z
No common RF definition
Thermal noise density
Typically not considered individually, but used for Eb/No
Can be calculated
No = KT – K is the Bolzman constant, 1.38*10^-23 – T is the temperature, 290 K
Typically the bandwidth noise and the receiver noise figure are also considered
No = 174 dBm/Hz under typical conditions
No = KTBNF, where NF is noise figure
To avoid confusion, NF should be used when referring to thermal noise
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page65
For a WCDMA system, the bandwidth is 3.84Mcps. For WCDMA, the typical noise figure is 3dB Uplink (NodeB, but Huawei’s NodeB is 2.2 dB in RND) and 7 dB downlink (UE). These figures should always be checked against the vendor specification, because implementation affects them
Based on the previous formula, this gives the total noise power (noise floor) as Uplink: -174+66+3= -105dBm (RTWP value without subscriber) Downlink: -174+66+7= -101dBm
These values are not the receiver sensitivity but the power measured at the reference point, in the absence of signal. As WCDMA allows the extraction of signals below the noise floor, the sensitivity can not be deducted from these values.
Symbol Explanation z
No for WCDMA system
Total one-sided noise power spectral density due to all noise sources
Typically not considered individually, but used for Eb/No
Defined this way, No and Io are substituted for one another:
On the uplink the substitution is valid
On the downlink, differentiating between Noise and Interference is more challenging
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page66
Originally, Eb/No meant simply bit energy divided by noise spectral density. However, over time the expression “Eb/No” has acquired an additional meaning. One reason is the fact that in CDMA the interference spectral density is added to the noise spectral density, since the interference is noise, due, for example, to spreading. Thus, No can usually be replaced by Io, interference plus noise density.
Symbol Explanation z
z
RTWP
Received Total Wide Bandwidth power
To describe uplink interference level
When uplink load increase 50%, RTWP value will increase 3dB
RSSI
Received Signal Strength Indicator
To describe downlink interference level at UE side
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Page67
Symbol Explanation z
z
RSCP
Revived Signal Code Power (Ec)
Ec/Io = RSCP/RSSI, to describe downlink CPICH quality
ISCP
Interference Signal Code Power; can be estimated by:
ISCP = RSSI – RSCP
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page68
Thank you www.huawei.com
WCDMA Radio Network Coverage Planning www.huawei.com
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Objectives z
Upon completion of this course, you will be able to:
Know the contents and process of radio network planning
Understand uplink budget and related parameters
Understand downlink budget and related parameters
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page1
Contents 1. WCDMA Radio Network Planning Process 2. R99 Coverage Planning 3. HSDPA Coverage Planning
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page2
Contents 1. WCDMA Radio Network Planning Process 2. R99 Coverage Planning 3. HSDPA Coverage Planning
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page3
Capacity, Coverage, Quality z
Capacity & Coverage
↑ Users Æ ↑ Cell Load Æ ↑ Interference
Capacity
Level Æ ↓ Cell Coverage
z
↑ Cell Coverage Æ Cell Load ↓ ÆCapacity ↓
COST
Capacity & Quality
↑ Users Æ ↑ Cell Load Æ ↑ Interference
Quality
Coverage
Level Æ ↓ Quality
z
↑ Quality ( BLERtar ↓ ) Æ ↓ Capacity
Coverage & Quality
↑ Quality ( AMR ↑ ) Æ ↓ Cell Coverage
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page4
z
Capacity–coverage (typical case: downlink load balance)
z
Capacity–quality (typical case: lowering BLER through outer loop power control)
z
Coverage–quality (typical case: lowering the data rate of the connections with much path loss through AMRC)
WCDMA Radio Network Planning Process z
Radio Network Planning (RNP) Process
Step1 : Radio network dimensioning
Step2 : Pre-planning of radio network
Step3 : Cell planning of radio network
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page5
3G radio network planning can be divided into three phases. They are shown in above figure, and consist of dimensioning, pre-planning and cell planning.
z
According to the above figure, the output result of radio network dimensioning stage serves as the input condition of the pre-planning, and the pre-planning is based on the network dimensioning and also checks the network dimensioning result. The site quantity can be adjusted according to the pre-planning result in order to obtain the reasonable sites. If the existing sites are considered in the selection of theoretical sites during the pre-planning, the pre-planning result will be more practical, thus facilitating the cell planning.
WCDMA Radio Network Planning Process z
Step1 : Radio network dimensioning
Radio network dimensioning includes coverage dimensioning and capacity dimensioning
Obtain the scale of sites and configuration according to input requirements when the coverage and capacity are balanced
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page6
z
Radio Network Dimensioning is a simplified analysis for radio network
z
Dimensioning provides the first and most rapid evaluation of the network element number as well as the associated capacity of those elements. The target of dimensioning phase is to estimate the required site density and site configurations for the area of interest. Dimensioning activities include radio link budget and coverage analysis, capacity evaluation and final estimation of the amount of NodeB hardware and E1, cell average throughput and cell edge throughput.
z
Objective:
z
To obtain the network scale ( approximate NodeB number and configuration)
Method:
Select a proper propagation model, traffic model and subscriber distribution, and then estimate the NodeB number, coverage radius, E1 number per site, cell throughput, cell edge throughput and so on.
WCDMA Radio Network Planning Process z
Input & output of radio network dimensioning Input Capacity Related -Spectrum Available -Subscriber Growth Forecast -Traffic Density
Coverage Related -Coverage Region -Propagation Condition -Area Type Information
QoS Related
9
Number of NodeB
9
Carrier configuration
9
CE configuration
9
Iub configuration
9
……
-Blocking Probability -Indoor Coverage -Coverage Probability
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page7
The service distribution, traffic density, traffic growth estimates and QoS requirements are already essential elements in dimensioning phase. Quality is taken into account here in terms of blocking and coverage probability.
WCDMA Radio Network Planning Process z
Step2 : Pre-planning of radio network – Initial Site Selection
Based on RND, radio network pre-planning is intended to determine:
Theoretical location of sites
Implementation parameters
Cell parameters
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page8
Wireless network dimensioning intends to obtain the approximate UTRAN scale. Based on the network dimensioning, geography and traffic distribution, the network is pre-planned in detail by using planning software and digital map.
z
Based on the network dimensioning and site information, the initially selected WCDMA site is imported into the planning software, and coverage is estimated by parameters setting. Then an analysis is made to check whether the coverage of the system meet the requirements. If necessary, the height and tilt of the antenna and the NodeB quantity are adjusted to optimize the coverage. And then the system capacity is analyzed to check whether it meets the requirement.
z
Implementation parameters, such as antenna type / azimuth / tilt / altitude / feeder type / length …
z
Cell parameters, such as transmission power of traffic channel and common channel, orthogonal factor, primary scrambling code…
WCDMA Radio Network Planning Process z
Step2 : Pre-planning of radio network - Prediction
Based on RND result, sites location, implementation parameters and cell parameters, we should predict coverage results such as best serving cell, pilot strength, overlapping zone
We should carry out detailed adjustment (such as NodeB number, NodeB configuration, antenna parameters) after analyzing the coverage prediction results
Finally ,we obtain proper site location and parameters that should satisfy coverage requirement
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page9
Based on the network dimensioning and site information, the initially selected WCDMA BS is imported into the planning software, and coverage is estimated by setting the cell parameters and engineering parameters. Then an analysis is made to check whether the coverage of the system meet the requirements. Then the system capacity is analyzed to check whether it meets the requirement. If necessary, the height and tilt angle of the antenna and the BS quality are adjusted to optimize the coverage.
WCDMA Radio Network Planning Process z
Step2 : Pre-planning of radio network - Prediction
Coverage by transmitter: Display the best server coverage
Coverage by signal level: Display the signal level across the studied area
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Overlapping zones: Display the signal level across the studied area
Page10
z
These graphs are prediction results of Huawei planning tool: U-Net
z
For the result of coverage prediction, focus on the distribution of best servers and pilot level. For the small areas with unqualified level, adjust the azimuth and down tilt to improve the coverage. For the large areas with weak coverage, analyze whether the site distance is over large:
If yes, add sites to improve coverage.
If no, check whether the configuration of parameters related to coverage prediction is correct.
WCDMA Radio Network Planning Process z
Step3 : Cell planning of radio network - Site Survey
We have to select backup location for site if theoretical location is not available
Based on experience , backup site location is selected in search ring scope , search ring =1/4×R
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page11
We should consider other factors when we select the backup sites
Commercial factor: rent
Radio propagation factor: situation / height / surrounding /
Implementation factor: space / antenna installation / transmission / power supply
WCDMA Radio Network Planning Process z
Step3 : Cell planning of radio network – Simulation
U-Net use Monte Carlo simulation to generate user distributions (snapshots)
By iteration, U-Net get the UL/DL cell load, connection status and rejected reason for each mobile
The example of Monte Carlo simulation:
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page12
Simulation is oriented to simulate the running situation of networks under the current network configuration so as to facilitate decision-making adjustment. Now there are two system simulation classes: static simulation and dynamic simulation.
z
Static simulation focus on user behavior such as browsing Internet, call. It would gain the performance of radio network based on “snapshot”.
z
Dynamic simulation focus on detail of user behavior such as duration and data rate of browsing. It would gain the performance of radio network based on analysis of mobile subscribers. But it requires higher precision of e-map.
z
At present, Static simulation is in common use. Monte Carlo simulation is one type of static simulation.
WCDMA Radio Network Planning Process z
The following takes coverage probability for an example to further understand how Monte Carlo simulation is performed
1st snapshot
3rd snapshot
2nd snapshot
Simulation result
100%
20%
60%
100%
0%
75%
60%
40%
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Page13
WCDMA Radio Network Planning Process z
Step3 : Cell planning of radio network – Simulation
Generate certain quantity of network instantaneous state (snapshot)
Obtain connection performance between terminals and UTRAN by incremental operation
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page14
Some UEs or terminals are distributed based on a certain rule (such as random even distribution) at each “snapshot”
z
It is required to consider the possibility of multiple connection failure (uplink/downlink traffic channel maximum transmit power, unavailable channels, low Ec/Io and uplink/downlink interference
WCDMA Radio Network Planning Process z
Step3 : Cell planning of radio network - Simulation
Measure and analyze results of multiple “snapshots” to have a overall understanding of network performance
Handover Status: Display areas depending on the probe mobile handover status
Pilot Quality (Ec/Io): Displays the pilot quality across the certain area
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Pilot Pollution: Displays pilot pollution statistics across the certain area Page15
These graphs are prediction results (based on simulation) of Huawei planning tool: UNet
z
The previous predictions (Coverage by transmitter, Coverage by signal level, Overlapping zones) are based on coverage, the predictions in this slide are based on simulation.
Contents 1. WCDMA Radio Network Planning Process 2. R99 Coverage Planning 3. HSDPA Coverage Planning
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page16
Contents 2. R99 Coverage Planning 2.1 Process of R99 Coverage Planning 2.2 R99 Uplink Budget 2.3 R99 Downlink Budget
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page17
Process of R99 Coverage Planning z
Goal of R99 coverage planning
obtain the cell radius
estimate NodeB number that could satisfy coverage requirement
Start Link Budget
R
Path Loss Propagation model
Cell Radius NodeB Coverage Area
R
NodeB number =
Total coverage area NodeB coverage area
3 Area = * 3R 2 2
NodeB Number End
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
9 Area = * 3R 2 8
Page18
In the coverage dimensioning, the link is estimated according to elements such as planned area, network capacity, and equipment performance in order to obtain the allowed maximum path loss. The maximum cell radius is obtained according to the radio propagation model and allowed maximum path loss. And then the site coverage area is calculated. Finally, the site quantity is calculated. Of course, the site quality is only for the ideal cell status, and some additional sites will be needed in actual terrain environment.
Contents 2. R99 Coverage Planning 2.1 Process of R99 Coverage Planning 2.2 R99 Uplink Budget 2.3 R99 Downlink Budget
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page19
Uplink Budget Principle Antenna Gain SHO Gain against Slow fading Pa th
Lo ss
Slow fading margin
SHO Gain against fast fading
Fast fading margin
NodeB Antenna Gain
Body Loss
Interference margin
Cable Loss UE Antenna Gain Cable Loss NodeB Sensitivity
UE Transmit Power
Penetration Loss
Penetration Loss
UPLINK BUDGET Antenna Gain SHO Gain
Maximum Allowed path loss
Margin Loss
NodeB reception sensitivity
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page20
Link dimensioning intends to estimate the system coverage by analyzing the factors of the propagation channels of the uplink signal and downlink signal. It is the link analysis model.
z
If the parameters such as transmit signal power, gain and loss of the transmitter and receiver, and quality threshold of received signal are known or estimated, the allowed maximum path loss used for ensuring the quality of received signal can be calculated.
Element of Uplink Budget 1. UE_TransmissionPower ( dBm )
The UE maximum transmit power is determined by the power class of the UE, which is specified by the 3GPP standard
The Class 4 UE, with maximum power 21 dBm, are normally considered due to their popularity in the market Grade of UE power （TS 25.101 ) Power Class
Nominal maximum output power
Tolerance
1
+33dBm
+1/-3dB
2
+27dBm
+1/-3dB
3
+24dBm
+1/-3dB
4
+21dBm
+2/-2dB
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page21
In network planning, the value should be set according to the UE capacity with lowest power grade in the commercial network of the operator.
z
Note that it is possible that a UE supporting high-speed uplink data service (higher than 64kbps) has a higher power grade than a UE supporting only voice and lowspeed data services, for example, power grade 3dBm ～ 24dBm.
z
With a higher maximum power rating, the maximum path loss is increased accordingly. This allows the operator to plan cells with a relatively larger coverage.
Ö
The UE cable loss, connector loss, and combiner loss are quite negligible, hence a 0 dB loss is assumed here。
Element of Uplink Budget 2. Body Loss ( dB )
For voice, the body loss is 3 dB
For the other service , the body loss is 0 dB
3. Gain of UE TX Antenna ( dBi )
In general, the gain of UE antenna is 0 dBi
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page22
The 0 dBi antenna gain is considered here with respect to the internal antenna of mobile phones.
Element of Uplink Budget 4. Penetration Loss ( dB )
Indoor penetration loss means the difference between the average signal strength outside the building and the average signal strength of first floor of the building
In terms of service coverage performance, micro-cells provide an effective solution for achieving a high degree of indoor penetration
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page23
The penetration loss is related to building type, incidence angle of the radio wave and so on. In the link budget, assume that the penetration loss obey the Log-Normal distribution. The penetration loss is related to mean value of penetration loss and standard deviation
z
When indoor coverage is required to coverage by outdoor macro NodeBs, building penetration loss needs to be considered. Building penetration loss is related to such factors as incidence angle of the radio wave, the building construction (the construction materials and number and size of windows), the internal building layout and frequency. Building penetration loss is highly dependent on specific environment and morphology and varies greatly. For instance, the wall thickness in Siberian tends to be larger than that of Singapore in order to resist coldness and hence the former’s building penetration loss is correspondingly larger.
z
In addition, sometimes vehicular coverage may be required and consequently vehicular penetration loss also needs to be included in link budget process. typical vehicular penetration loss is around 8dB.
Element of Uplink Budget Sector Type
Gain of Antenna (dBi)
Omni
11
2 Sector
18
3 Sector
18
6 Sector
20
6. Cable loss ( dB ) - Cable loss between NodeB and antenna
Cable Loss
5. NodeB_AntennaGain ( dB )
- Jumper loss between NodeB and antenna - Connectors loss between NodeB and antenna
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page24
z
Antenna gain: It refers to the ratio of the square of the actual field of an antenna at a point in the space to the square of the field of an ideal radiation unit at the same point in the space, namely power ratio. It is the gain in the main transmit direction. In general, the gain is related to the antenna pattern. If the central lobe is narrow and the back lobe and side lobe are small, the gain is high. If the transmit direction is centralized, the antenna gain is high. For an omnidirectional antenna, the gain in all the directions is the same.
z
Front-to-back ratio: It refers to the ratio of the maximum gain in the principal direction to the gain in the reverse direction. It describes the directing feature. If it is high, the directed receive performance of the antenna is high.
z
Beam width: It refers to the separation angle between the main transmit direction of the power and the point with 3 dB of transmit power reduced, and the area is called an antenna lobe. Tilt: It refers to the tilt angle of a directional plate antennal. It is used to control interference and improve coverage.
z
Polarization: The vector direction of the electrical field in the direction with the highest radiation. A dual polarized antenna can provide diversity over a single antenna, thus saving one antenna.
z
In general, there are two or more lobes in an antenna pattern. The largest lobe is the central lobe, and others are side lobes. The separation angle between the two halfpower points of the central lobe is the lobe width of the antenna pattern, namely, halfpower (angle) lobe width. If the central lobe is narrow, the directivity is high, and the anti-interference capability is high.
Element of Uplink Budget z
Path Loss and Fading
Path Loss - fading due to propagation distance
Long term (slow) fading - caused by shadowing
Short term (fast) fading - caused by multi-path propagation
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page25
Radio propagation in the land mobile channel is characterized by multiple reflections, diffractions and attenuation of the signal energy. These are caused by natural obstacles such as buildings, hills, and so on, resulting in so-called multi-path propagation. Furthermore, with the moving of a mobile station, the signal amplitude, delay and phase on various transmission paths vary with time and place. Therefore, the levels of received signals are fluctuating and unstable and these multi-path signals, if overlaid, will lead to fading i.e. short term fading. The mid-value field strength of Rayleigh fading has relatively gentle change and is called “Slow fading” i.e. long term fading. And it conforms to lognormal distribution.
z
Long term fading– the variation of signal level is slow and smooth.
z
Short term fading– the variation of signal level is fast and poignant
Element of Uplink Budget 7. Slow Fading Margin
Slow Fading Margin depends on
Coverage Probability @ Cell Edge The higher the coverage probability is, the more SFM is required
Standard Deviation of Slow Fading
Probability Density
The higher the standard deviation is, the more SFM is required SFM required
Coverage CoverageProbability Probability@ @Cell CellEdge: Edge:
PPCOVERAGE (x) = P [ F(x) > Fthreshold ] COVERAGE (x) = P [ F(x) > Fthreshold ] Without SFM With SFM Fthreshold Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Received Signal Level [dBm] Page26
z
Slow Fading --- Signal levels obey Log-Normal distribution
z
Propagation models predict only mean values of signal strength , the mean value of signal strength fluctuates. The deviation of the mean values has a nearly normal distribution in dB, The variation in mean values is called log-normal fading.
z
Probability that the real signal strength will exceed the average one on the cell border is around 50%,for higher than 50% coverage probability an additional margin has to be introduced. The margin is called slow fading margin.
z
Slow Fading Margin (SFM) is related with coverage probability in cell edge and standard deviation of slow fading. The equation is described as following:
z
The standard deviation is a measured value that is obtained from various clutter types. It basically represents the variance (log-normally distributed around the mean value) of the measured RF signal strengths at a certain distance from the site.
z
Therefore, the standard deviation would vary by clutter type. Depending on the propagation environment, the log-normal standard deviation can easily vary between 6 and 8 dB or even greater. Assuming flat terrain, rural or open clutter types would typically have lower standard deviation levels than the suburban or urban clutter types. This is due to the highly obstructive properties encountered in an urban environment that in turn will produce higher standard deviation to mean signal strengths than that experienced in a rural area. Standard Deviation of slow fading is related with morphology, frequency and environment. For instance:
Element of Uplink Budget 8. SHO Gain against Slow Fading
SHO reduces slow fading margin compared to the single cell case
SHO gain against slow fading can improve the coverage probability
SHO Gain against slow fading = SFM without SHO - SFM with SHO SHO Gain Against SFM
(dB) 7 6 5 4 3 2 1 0
Standard deviation=11.7 Path loss slope=3.52
98%
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
95%
92%
90%
85%
Area coverage probability
Page28
z
Soft Handover --- handover between different NodeBs
z
Softer Handover --- handover between cells in a NodeB
z
SHO gain over slow fading is also known as the Multi-Cell gain because in soft handover more than 1 branch exists and hence the coverage probability increases which would result in the decreasing of required slow fading margin.
z
Suppose that soft handover has 2 branches, and the orthogonality of the two radio link branches on slow fading is 50%. We can calculate the slow fading margin required with soft handovers based on the former assumptions, and compare it with the slow fading margin required without soft handover to get the SHO gain over slow fading.
z
SHO gain over slow fading is dependent on the required area coverage probability, the propagation path loss slope and the STD. The following table gives the calculated SHO gain over slow fading and the propagation path loss slope equals to 3.59.
Element of Uplink Budget 9. Fast Fading Margin
Fast fading margin
required to guarantee fast power control
the factors affect FFM include channel model, service type, BLER requirement
Fast Fading Margin= Eb/No without fast PC - Eb/No with fast PC
Uplink case: UE moves towards the edge of the cell
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
z
Page29
Fast power control
to enhance weak signal caused by Rayleigh fading
to mitigate interference and enhance the capacity
to promote power utilization efficiency
In WCDMA, user signals should be received at the NodeB with equal power all the time and for downlink the transmitted TCH power should be as small as possible while maintaining the required Qos. This implies that fast fading are compensated by the power control algorithm, which requires additional headroom at both UE and NodeB in order to let UE and NodeB following the power control commands at cell edge.
Element of Uplink Budget 10. SHO Gain against Fast fading
SHO gain against fast fading reduces the Eb/No requirement
SHO gain against fast fading leads to a gain for reception sensitivity
SHO gain against fast fading exists for both uplink and downlink (Typical value of SHO gain against FFM is 1.5dB)
SHO Gain Against Fast Fading = Eb/No without SHO – Eb/No with SHO
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page30
Because of the macro diversity combination, the soft handover reduces the required Eb/No by a single radio link, which results in additional macro diversity gain.
Element of Uplink Budget 11. Interference Margin in Uplink
Interference Margin is equal to Noise Rise N oiseR ise = − 10 ⋅ L og 10 (1 − η U L )
[dB ]
Higher cell load leads to heavier interference
Interference margin affects cell coverage NoiseRise(dB)
Interference Curve in Uplink
50% UL Load — 3dB 60% UL Load — 4dB 75% UL Load — 6dB
UL Load Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page31
Interference margin is the required margin in the link budget due to the noise rise caused by system load (the noise rise due to other subscribers). The higher the system load is, the larger the interference margin should be.
Element of Uplink Budget 12. NodeB Reception Sensitivity Re ceptionSen sitivity = N th + NF + E b / N 0 − PG
Nth : Thermal Noise
NF: Noise Figure
Eb/No : required Eb/No to maintain service quality
PG: Processing Gain
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Page32
Element of Uplink Budget 12. NodeB Reception Sensitivity
Nth : Thermal Noise is the noise density generated by environment and equals to:
N th = 10 log( K * T * W )
K：Boltzmann constant, 1.38×10-23J/K
T：Temperature in Kelvin, normal temperature: 290 K
W：Signal bandwidth, WCDMA signal bandwidth 3.84MHz
Nth = -108dBm/3.84MHz
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z
If the W=1Hz, Nth=-174dBm/Hz
z
If the W=200kHz, Nth=-121dBm/200kHz
Page33
Element of Uplink Budget 12. NodeB Reception Sensitivity
NF: Noise Figure :
For Huawei NodeB, latest NF is 1.6dB
For commercial UE, typical NF is 7dB.
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page34
Typical noises are: external sky and electric noise, vehicle start-up noise, heat noise from inside systems, scattered noise of transistor during operation, intermodulation product of signal and noise.
z
Noise figure is used for measuring the processing capability of the RF component for small signals, and is usually defined as: output SNR divided by unit input SNR.
Si NF
Ni So No
Element of Uplink Budget 12. NodeB Reception Sensitivity
PG: Processing Gain :
Processing gain is related with the service bearer rate, and the detail formula is present below:
Pr ocess Gain = 10 log(
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
chip rate ) bit rate
Page35
For common services, the bit rate of voice call is 12.2kbps, the bit rate of video phone is 64kbps, and the highest packet service bit rate is 384kbps(R99). After the spreading, the chip rate of different service all become 3.84Mcps.
Element of Uplink Budget 12. NodeB Reception Sensitivity
Eb/No is required bit energy over the density of total noise to maintain service quality
Eb/No is obtained from link simulation
Eb/No is related to following factors
Service type
Multi-path channel model
User speed
The target BLER
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page36
For instance: Service
BLER
AMR12.2k
1.00%
CS64k
CS64k
0.10%
1.00%
Channel Model
Uplink Eb/N0
Downlink Eb/N0
TU3
5.4dB
7.8 dB
RA120
4.5 dB
8.3 dB
TU3
2.8 dB
6.3 dB
RA120
2.8 dB
6.8 dB
TU3
2.5 dB
5.4 dB
RA120
2.3 dB
6 dB
Contents 2. R99 Coverage Planning 2.1 Process of R99 Coverage Planning 2.2 R99 Uplink Budget 2.3 R99 Downlink Budget
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Page37
Downlink Budget Principle Antenna Gain
Pa th
SHO Gain against Slow fading
Slow fading margin
SHO Gain against fast fading
Fast fading margin Interference margin
Lo ss
NodeB Antenna Gain
Body Loss Cable Loss
UE Antenna Gain NodeB Transmit Power
CableLoss Penetration Loss
UE Sensitivity
Penetration Loss
DOWNLINK BUDGET Antenna Gain
Maximum allowed path loss
SHO Gain Margin Loss
UE reception sensitivity
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Page38
Element of Downlink Budget z
Interference Margin in Downlink NoiseRise =
I total PN + I own + I other No + (α + f )× PMax ⋅η DL / CL = = PN PN PN
Wherein, α is non-orthogonality factor, f is the interference ratio of other cell to own cell
Interference margin is equal to noise rise Interference Margin
IM(dB) 30.00 25.00
α =0.6, f PMax=20W,
= 1.78,
η DL = 0.9
20.00 15.00 10.00 5.00 0.00 120
125
130
135
140
145
150
CL(dB) Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page39
In case of multi-path propagation, certain energy will be detected by the RAKE α receiver, and become interference signals. We define the orthogonal factor to describe this phenomenon. It is obtained through simulation, and related to environment type and cell radius.
Case Study : R99 Uplink Budget
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page40
Case Study : R99 Downlink Budget
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Page41
Contents 1. WCDMA Radio Network Planning Process 2. R99 Coverage Planning 3. HSDPA Coverage Planning
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Page42
Link Budget Difference of HSDPA and R99 z
z
Coverage Requirement
R99: Based on target continuous coverage service
HSDPA: Based on cell edge throughput
Simulation KPI
R99: Connect Success Rate, Coverage Probability, Pilot Pollution Proportion and SHO
HSDPA: Cell Average Throughput and Cell Edge Throughput
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page43
Continuous coverage target service requirement with specific coverage probability should be given for R99
z
Cell edge throughput requirement with specific coverage requirement should be given for HSDPA
Link Budget Difference of HSDPA and R99 z
Target Network Load
R99: DL target load should be set to 75%
HSDPA: DL target load can be raised to 90% HSDPA power
Cell total power
Cell total power
90%
R99 DCH Power
R99 DCH Power
75%
CCH
CCH
More power to ensure R99 capacity
time
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
time
Page44
The cell total transmit power is the constant resources. The DL power consists of the following three parts:
Power of the HSPA DL physical channel (HS-PDSCH, and HS-SCCH)
Common channel power
DPCH power
Link Budget Difference of HSDPA and R99 z
Other Parameters
R99:
Power control margin should be considered.
SHO gain should be considered.
HSDPA:
Power control margin need not be considered.
SHO gain should not be considered for HSDPA.
Other elements: Number of HS-PDSCH, HSDPA power, etc.
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page45
Fast power control
For R99, power control margin should be considered
For HSDPA, the maximum transmission power for HS-PDSCH is the remaining power excluding R99 power and power margin, and no power control margin
z
z
SHO gain
For R99, SHO gain should be considered
For HSDPA, only hard handover, no SHO gain
HSDPA related parameters should be configured when simulation
Max number of HS-PDSCH channel
Min number of HS-PDSCH channel
HSDPA power allocation, dynamic or fixed
HS-SCCH power allocation, dynamic or fixed
Max number of HSDPA users
Scheduling Algorithm
HSDPA Deployment Strategy Mature Phase Focus on:
HSDPA+R99
f2
HSDPA+R99
R99+HSDPA
f1
R99+HSDP A
R99+HSDPA
HSDPA+R99
f2
R99
f1
R99+HSDPA
R99
Urban
Suburban & Rural
HSDPA Performance
Initial Phase Focus on: HSDPA coverage no impact on R99
Hot Spot & Dense Urban Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page46
Single carrier for HSDPA and R99
Advantages
Maximum resource utilization efficiency
Save cost Disadvantages
z z
Handover between HSDPA cell and R99 cell
Two carriers for HSDPA and R99
Advantages
Fewer inter-frequency handover for HSDPA user Disadvantages
High cost
HSDPA Link Budget Categories HSDPA+R99 HSDPA Throughput Requirement Guarantee R99 CS Traffic Capacity R9 9
Not Change R99 Coverage
R99 requirement should be met first, and then HSDPA throughput !
HSDPA Throughput Requirement No WCDMA
HSDPA+R9 9
R99/R4 Capacity, Coverage Requirement
R99 and HSDPA requirement should be met simultaneously !
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page47
If operator wants to upgrade HSDPA from R99, R99 should be met first, and HSDPA should not affect the R99.
z
If operator setup R99 and HSDPA directly, R99 and HSDPA requirement should be met at the same time.
HSDPA Link Budget Element z
DL Coupling Loss
DL _ CouplingLo ss = PL _ DL + Lf _ BS − Ga _ antenna + Lb + SFM NSHO + Lp
z
Cell edge Ec/No
Ec = 10 × log( No
PHS − DSCH
(α + f )× η DL × Pmax
+ 10
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
z
DL _ CoupleLoss ＋ NF ＋ Nt 10
Page48
DL Coupling Loss :
PL_DL: Downlink path loss
Lf_BS: cable loss of NodeB
Ga_antenna: Gain of UE antenna and NodeB antenna
Lb: Body loss
SFMNSHO: Slow fading margin without soft handover
Lp: Penetration loss
Cell edge Ec/No:
PHS-DSCH : total power of HS-DSCH channel
α : non-orthogonality factor
f : neighbor cell interference factor
η DL : downlink load factor including R99 and HSDPA service
Pmax : max transmission power of downlink
Nt : thermal noise power spectral density , typical value is -108.16dB
NF : receiver noise figure of UE, typical value is 7dB
)
HSDPA Link Budget Principle z
Goal of HSDPA link budget
The HSDPA link budget is usually based on the R99 link budget to get the cell edge throughput in downlink
The HSDPA cell edge throughput need to be calculate depend on simulation results, which is related with cell edge Ec/No
z
Simulation Conditions
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Channel model-TU3
5 codes
Page49
z
The theoretical maximum throughput is decided by the number of HSDPA codes.
z
For HSDPA , soft handover gain and fast fading margin should not be considered in link budget , since neither power control nor soft handover in HS-PDSCH channel
HSDPA Link Budget Principle z
According to R99 Cell Radius and HSDPA Power Allocation, calculate Cell Edge Throughput
R99 Network Cell Radius
Downlink Path Loss
DL_CoupleLoss=DL_PL+TxBodyLoss+TxCableLoss-TxAntennaGain+RxBodyLoss+ RxCableLoss-RxAntennaGain+PenetrationLoss+SlowFadingMargin
Downlink Coupling Loss
Ec/No at Cell Edge
HSDPA power
Ec = 10 × log( No
PHS − DSCH
(α + f )×η DL × Pmax + 10
DL _ CoupleLoss＋NF＋Nt 10
Simulation Results
Cell Edge Throughput Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page50
The step is present below:
According to the Cell Radius comes from R99 dimensioning, the Downlink Path Loss can be calculated
According to the Downlink Path Loss , the Downlink Coupling Loss can be calculated
According to the Downlink Coupling Loss and HS-DSCH Power, Cell Edge Ec/No can be calculated
According to the Cell Edge Ec/No and simulation result, Cell Edge Throughput can be calculated
)
HSDPA Link Budget Principle z
According to Cell Edge Throughput requirement and HSDPA Power Allocation, calculate HSDPA Cell Radius
Cell Edge Throughput Simulation results
Ec/No at Cell Edge HSDPA power
Downlink Coupling Loss
PHS − DSCH − (α + f )×η DL × Pmax Ec No DL _ CoupleLoss = NF＋Nt
Downlink Path Loss
DL_CoupleLoss=DL_PL+TxBodyLoss+TxCableLoss-TxAntennaGain+RxBodyLoss+ RxCableLoss-RxAntennaGain+PenetrationLoss+SlowFadingMargin
HSDPA Cell Radius Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page51
The step is present below:
According to the Cell Edge Throughput and simulation result, Cell Edge Ec/No can be calculated
According to the Cell Edge Ec/No and HS-DSCH Power, the Downlink Coupling Loss can be calculated
According to the Downlink Coupling Loss, the Downlink Path Loss can be calculated
According to the Downlink Path Loss and and Propagation Model, HSDPA Cell radius can be calculated
HSDPA Link Budget Principle z
According to Cell Edge Throughput requirement and Cell Radius, calculate HSDPA Power Cell Radius
Cell Edge Throughput Simulation results
Ec/No at Cell Edge
Downlink Path Loss
Downlink Coupling Loss
PHSDPA = PHS − DSCH + PHS − SCCH =
( DL _ CoupleLoss × Nt × NF + (α + f ) ×η DL × Pmax ) × Pmax
Ec No + P HS − SCCH
HSDPA Power
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page52
The step is present below:
According to the Cell Radius comes from R99 dimensioning, the Downlink Path Loss can be calculated
According to the Downlink Path Loss , the Downlink Coupling Loss can be calculated
According to the Cell Edge Throughput and simulation result, Cell Edge Ec/No can be calculated
According to the Downlink Coupling Loss and Cell Edge Ec/No , HS-DSCH Power can be calculated
Case Study – HSDPA Link Budget z
Assumption:
Downlink maximum path loss: 129.06 dB
Cable loss : 0.5 dB
NodeB antenna gain : 18dBi
Penetration loss : 20dB ( required in indoor coverage )
Body loss : 0 dB
Slow fading margin without soft handover gain against SFM : 13.1
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Page53
Case Study – HSDPA Link Budget z
Assumption:
Channel type: TU3
Non-orthogonality factor: 0.5
Adjacent cell interference factor: 1.78
HSDPA code resource: 5
Cell radius: 0.36 km
UE Category: 8
Max transmitter power of downlink: 20000 mW
Total power of HSDPA: 6000 mW (30% downlink power allocation)
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page54
Case Study – HSDPA Link Budget z
According to the assumption above, the DL Coupling Loss for HSDPA is calculated below: DL _ CouplingLo ss = PL _ DL + Lf _ BS − Ga _ antenna + Lb + SFM NSHO + Lp = 129.06 + 0.5 - 18 + 0 + 13.1 + 20 = 144.66dB
z
Cell Edge Ec/No will be carry out base on equation below: Ec = 10 * log( No = 10 * log(
PHS − DSCH
(α
+ f )× η DL × Pmax + 10
DL _ CoupleLoss ＋ NF ＋ Nt 10
6000 ( 0 . 5 + 1 . 78 ) * 0 . 9 * 20000 + 10
z
144 . 66 −108 . 16 + 7 10
)
) = − 10 . 2 dB
Base on the simulation result, the Cell Edge Throughput for HSDPA can be obtained is 173.80 Kbps
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page55
Thank you www.huawei.com
WCDMA Radio Network Capacity Planning www.huawei.com
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Foreword z
WCDMA is a self-interference system
z
WCDMA system capacity is closely related to coverage
z
WCDMA network capacity has the “soft capacity” feature
z
The WCDMA network capacity restriction factors in the radio network part include the following:
Uplink interference
Downlink power
Downlink channel code resources (OVSF)
Channel element (CE)
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page1
Objectives z
Upon completion of this course, you will be able to:
Grasp the parameters of 3G traffic model Understand the factors that restrict the WCDMA network capacity Understand the methods and procedures of estimating multiservice capacity Understand the key technologies for enhancing network capacity
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page2
Contents 1. Traffic Model 2. Interference Analysis 3. Capacity Dimensioning 4. CE Dimensioning 5. Network Dimensioning Flow
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page3
Contents 1. Traffic Model 2. Interference Analysis 3. Capacity Dimensioning 4. CE Dimensioning 5. Network Dimensioning Flow
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page4
Contents 1. Traffic Model 1.1 Overview of traffic model 1.2 CS traffic model 1.3 PS traffic model
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page5
QoS Type Real-time category
It is necessary to maintain the time relationship
Voice service,
Conversation
between the information entities in the stream.
videophone
al
Small time delay tolerance, requiring data rate symmetry
Streaming
Non real-time category
Interactive
Background
Typically unidirectional services, high
Streaming
requirements on error tolerance, high
multimedia
requirements on data rate Request-response mode, data integrity must be
Web page
maintained. High requirements on error tolerance, browse, low requirements on time delay tolerance
network game
Data integrity should be maintained. Small delay
Background
restriction, requiring correct transmission
download of
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Email
Page6
z
For the session-type service, requirement on end-to-end delay is strict. For example, for the voice service, the delay is required to be smaller than 150ms, and must not exceed 400ms, otherwise, it will be difficult to understand the voice. The session-type services are typically carried by the CS domain. For the session-type services, the system can perform no queue processing for the calls. In this case, we can use the Erlang B formula or the extended Erlang B formula to calculate.
z
Compared with the session-type service, the stream-type service imposes low requirement on the end-to-end delay. Generally, the stream-type service tolerates the call waiting to a greater extent, and can provide the call queue mechanism. In this case, we can use the Erlang C formula to calculate the blocking probability of this type of users (defined as the probability of the call waiting for a specified time).
z
Interaction-type service refers to the service through which the user requests data from the server. The service is described with the terminal user’s request response pattern. Therefore, round-trip delay is the most important index of this service type. The interaction-type services are typically carried on the CS domain. The background-service tolerates delay to the greatest extent, and can tolerate the delay of a magnitude of an hour. Due to such great delay tolerance, the system can save such requests in the busy hour, and respond when the channel becomes idle; meanwhile, for such services, once a request with higher QoS comes in, the processing can be stopped at any time. The system decides startup and termination at any time, the above formulas—Erlang B formula and Erlang C formula are not applicable. Generally, according to the difference between the maximum number of channels and the busy-hour average occupied channels, we can calculate the traffic of the background-type service. The users of traffic-type services also tolerate the call waiting to some extent. The system provides a queue mechanism, and uses the Erlang C formula to calculate the blocking rate.
Traffic Model Service Pattern Traffic Model Results User Behaviour
System Configuration
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page7
By determining the service pattern and the user behaviour parameters, we determine the traffic models of various services in the network. By calculating the hybrid services of multiple traffic models, we determine the network system configuration.
The Contents of Traffic Model z
Service pattern refers to the service features
z
User behaviour refers to the conduct of people in using the service
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page8
Service pattern is a means of researching the capacity features of each service type and the QoS expected by the users who are using the service from perspective of data transmission. In the actual application, service pattern is closely related to, and sometimes is no strictly different from, the traffic measurement model.
z
In the data application, the user behaviour research mainly forecasts the service types available from the 3G, the number of users of each service type, frequency of using the service, and the distribution of users in different regions
Typical Service Features Description z
Typical service features include the following feature parameters:
User type (indoor ,outdoor, vehicle)
User’s average moving speed
Service Type
Uplink and downlink service rates
Spreading factor
Time delay requirements of the service
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page9
For each service, since the channel structure and demodulation method are different, the required uplink rate is different from the required downlink rate even for the same service type and the same data rate. For a typical service, we first need to identify whether it is uplink or downlink rate. A typical service can be described by the following parameters:
z
User type (indoor users, users inside a vehicle, outdoor users)
User’s average moving speed (km/h)
Voice, real-time data, non real time data
Uplink and downlink service rates (kbps)
Spread factor (SF)
Signal delay requirement of the service (ms).
The above parameters ultimately determine the QoS requirements of the service.
Contents 1. Traffic Model 1.1 Overview of traffic model 1.2 CS traffic model 1.3 PS traffic model
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page10
CS Traffic Model z
Voice service is a typical CS services. Voice data arrival conforms to the Poisson distribution. Its time interval conforms to the exponent distribution
z
Key parameters of the model
Penetration rate
BHCA: busy-hour call attempts
Mean call duration (s)
Activity factor
Mean rate of service (kbps)
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page11
Penetration rate: The percentage of the users that activates this service to all the users registered in the network.
z
Activity Factor: The weight of the time of service full-rate transmission among the duration of a single session.
CS Traffic Model Parameters z
Mean busy-hour traffic (Erlang) per user = BHCA × mean call duration /3600
z
Mean busy hour traffic volume per user (kbit) = BHCA × mean call duration × activity factor × mean rate
z
Mean busy hour throughput per user (bps) = mean busy hour traffic volume per user × 1000/3600
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page12
(Erl) For CS service, mean busy-hour traffic (Erlang) per user = BHCA * mean call duration /3600 (Erl)
z
(kbps) Mean busy-hour throughput per user = BHCA * mean call duration * activity factor * mean rate of service*1000/3600 (kbps)
Contents 1. Traffic Model 1.1 Overview of traffic model 1.2 CS traffic model 1.3 PS traffic model
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page13
PS Traffic Model Session
Packet Call
Packet Call
Downloading
Active
Downloading
Dormant
Dormant
Active
Packet Call
Data Burst
Data Burst
Data Burst
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page14
The most frequently used model is the packet service session process model described in ETSI UMTS30.03.
PS Traffic Model Parameters Packet Call Num/Session Packet Num/Packet Call Traffic Model
Packet Size (bytes) Reading Time (sec) Typical Bear Rate (kbps) BLER
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page15
The service pattern-related parameters in the traffic model include: these parameters commonly determine the pattern of one session.
z
z
We identify the service types through the different values of the parameters.
Packet Call Num/Session: Takes on the geometric random distribution
Reading Time (sec): Takes on the geographic random distribution
Packet Num/Packet Call: Takes on the geographic random distribution
Packet size: Takes on the Pareto random distribution
When using the parameters, the average values will apply.
Parameter Determining z
The basic parameters in the traffic model are determined in the following ways:
Obtain numerous basic parameter sample data from the existing network
Obtain the probability distribution of the parameters through processing of the sample data
Take the distribution most proximate to the standard probability as the corresponding parameter distribution through comparison with the standard distribution function
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page16
We have determined the traffic model parameters. The linchpin is to determine such parameter values. The parameter value varies between different services. Pareto General standard probability distributions include: logarithmic normal distribution, Pareto distribution, geometrical distribution, and negative exponent distribution.
PS User Behaviour Parameters
Penetration Rate BHSA
User Behaviour
User Distribution (High, Medium, Low end)
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page17
The country, region, life custom and economic level will affect the service distribution. In the planning, we divide the users into high-end users, mid-end users and low-end users, and believe that the BHSA and penetration rate are different between different types of user groups. Currently, we can only use the existing analysis to make prediction. In the future, the progress of the construction of the WCDMA pilot system will provide us with reference.
PS User Behaviour Parameters z
Penetration Rate
z
BHSA
z
The times of single-user busy hour sessions of this service
User Distribution (High, Medium, Low end)
The users are divided into high-end, mid-end and low-end users.
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page18
Penetration Rate: The percentage of the users that activate this service to all the users registered in the network. It varies between different service types, user types, and operators. More importantly, it is related to the penetration rate and time. With the elapse of time, the penetration rate will increase gradually.
z
BHSA: Times of the single-user busy hour sessions of the service. It varies between service types and user types.
z
User Distribution (High, Medium, Low end): The users are divided into high-end, mid-end and low-end users according to the ARPU. Different operators and different application situations will have different user distributions.
PS Traffic Model Parameters z
Data Transmission time (s): The time in a single session of service for purpose of transmitting data.
DataTransm issionTime = z
Holding Time (s): Average duration of a single session of service
HoldingTim e = ( z
SessionTra fficVolume × 8 / 1000 1 × 1 − BLER TypicalRat e
PackketCal lNum − 1 ) × Re adingTime + DataTransm issionTime Session
Activity Factor:
ActivityFactor =
DataTransm issionTime HoldingTim e
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page19
In the PS service, when calculating the data transmission time, the retransmission caused by erroneous blocks should be considered. Suppose the data volume of service source is N, the air interface block error rate is BLER, the total required data volume to be transmitted via the air interface is
N + N * BLER + N * BLER 2 + N * BLER 3 + Λ Λ + N * BLER n =
1 *N 1 − BLER
Contents 1. Traffic Model 2. Interference Analysis 3. Capacity Dimensioning 4. CE Dimensioning 5. Network Dimensioning Flow
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page20
Basic Principles z
In the WCDMA system, all the cells use the same frequency, which is conducive to improving the WCDMA system capacity. However, for reason of co-frequency multiplexing, the system incurs interference between users. This multiaccess interference restricts the capacity in turn.
z
The radio system capacity is decided by uplink and downlink. When planning the capacity, we must analyze from both uplink and downlink perspectives.
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page21
Interference is the main factor that decides the system performance of the cellular system. The interference in a cellular system consists of two parts: co-frequency and adjacent frequency interference. All users in the WCDMA system use the same band. All the users are different by modulating the respective signal to the code sequences that are mutually orthogonal. Therefore, the receiving signal is the sum of all user signals and the channel noise.
Contents 2. Interference Analysis 2.1 Uplink Interference Analysis 2.2 Downlink Interference Analysis
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page22
Uplink Interference Analysis z
Uplink interference analysis is based on the following formula:
I TOT = I own + I other + PN
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Where:
I TOT I own
: Total interference received by NodeB : Interference from the users of this cell
I other : Interference from the users of adjacent cells PN
: Noise floor of the receiver
Page23
Uplink Interference Analysis z
Receiver noise floor: PN
PN = 10 log( K * T * W ) + NF
For Huawei NodeB, the typical value is -106.4dBm/3.84MHZ
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
K: Boltzmann constant, 1.38×10-23J/K
z
T: Temperature in Kelvin, normal temperature: 290 K
z
W: Signal bandwidth, WCDMA signal bandwidth 3.84MHz
z
Nth = 10log(K*T*W)=-108dBm/3.84MHz
z
NF: For Huawei NodeB, typical value is 1.6dB.
Page24
Uplink Interference Analysis z
I own : Interference from users of this cell
Interference that every user must overcome is : I total − P j
Pj is the receiving power of the user j ,ρ j ( Eb / No ) Avg
Under the ideal power control 10 : Hence:
Pj =
I TOT 1+
( Eb
10
10
1 / No
) Avg
_ j
⋅
10
is UL activity factor _ j
=
Pj I TOT − P j
⋅
W 1 ⋅ Rj ρ j
1 W ⋅ Rj ρj
The interference from users of this cell is the sum of power of all the users arriving at the receiver:
I own =
N
∑
Pj
1
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page25
Activity Factor: The weight of the time of service full-rate transmission among the duration of a single session. Which is defined by the following formula: ActiveFactor =
DataTransm issionTime HoldingTim e
Uplink Interference Analysis z
I other :Interference from users of adjacent cell
The interference from users of adjacent cell is difficult to analyze theoretically, because it is related to user distribution, cell layout, and antenna direction diagram.
Adjacent cell interference factor ：
f =
I other I own
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page26
When the users are distributed evenly
For omni cell, the typical value of adjacent cell interference factor is 0.55
For the 3-sector directional cell, the typical value of adjacent cell interference factor is 0.65
Uplink Interference Analysis I TOT = I own + I other + PN = (1 + f
N
)∑ 1
I TOT 1
1+
( Eb / No ) Avg _ j 10
10
Define:
Lj =
1 1
1+
( Eb / No ) Avg _ j
10
10
⋅
W 1 ⋅ Rj ρ j N
Then:
I TOT = I TOT ⋅ (1 + f ) ⋅ ∑ L j + PN 1
Obtain:
I TOT = PN ⋅
1 N
1 − (1 + f ) ⋅ ∑ L j 1
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Where:
W 1 ⋅ ⋅ Rj ρ j
N is the number of users in the cell.
Page27
+ PN
Uplink Interference Analysis z
Suppose that:
All the users are 12.2 kbps voice users, Eb/NoAvg = 5dB
Voice activity factorρ j = 0.67
Adjacent cell interference factor f=0.55
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page28
Under the above assumption, the threshold capacity is approx 96 users.
Uplink Interference Analysis z
According to the above mentioned relationship, the noise will rise: I 1 1 = NoiseRise = TOT = N PN 1 −ηUL 1 − (1 + f )∑ L j 1
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page29
z
The NoiseRise is used in link budget to estimate the Interference Margin
z
If uplink cell load is 50%, NoiseRise will be 3dB
z
If uplink cell load is 60%, NoiseRise will be 4dB
z
If uplink cell load is 75%, NoiseRise will be 6dB
Uplink Interference Analysis z
Define the uplink load factor for one user:
η j = (1 + f )× L j = (1 + f )×
1 1
1+
( EbvsNo) Avg _ j
10 z
10
W 1 ⋅ Rj ρ j
Define the uplink load factor for the cell: N
N
1
1
ηUL = (1 + f )× ∑ L j = (1 + f )× ∑
1 1
1+
( EbvsNo)Avg _ j
10 Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
⋅
10
⋅
W 1 ⋅ Rj ρ j
Page30
When the uplink load factor is 1, I TOT is infinite, and the corresponding capacity is called “threshold capacity”.
Uplink Interference Analysis Limitation z
The above mentioned theoretic analysis uses the following simplifying explicitly or implicitly:
No consideration of the influence of soft handover
No consideration of the influence of AMRC and hybrid service
Ideal power control assumption
z
Assume that the users are distributed evenly, and the adjacent cell interference is constant
Considering the above factors, the system simulation is a more accurate method:
Static simulation: Monte_Carlo method
Dynamic simulation
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page31
No consideration of the influence of soft handover
The users in the soft handover state generates the interference which is slightly less than that generated by ordinary users.
z
No consideration of the influence of AMRC and hybrid service
AMRC reduces the voice service rate of some users, and makes them generate less interference, and make the system support more users. (But call quality of such users will be deteriorated)
Different services have different data rates and demodulation thresholds. So, we should use the previous methods for analysis, but it will complicate the calculation process.
Since the time-variable feature of the mobile transmission environment, the demodulation threshold even for the same service is time-variable.
z
Ideal power control assumption
The power control commands of the actual system have certain error codes so that the power control process is not ideal, and reduces the system capacity
z
Assume that the users are distributed evenly, and the adjacent cell interference is constant
Contents 2. Interference Analysis 2.1 Uplink Interference Analysis 2.2 Downlink Interference Analysis
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page32
Downlink Interference Analysis z
Downlink interference analysis is based on the following formula:
I TOT = I own + I other + PN
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page33
Where:
I TOT I own
: Total interference received by UE : Interference from downlink signal of this cell
I other : Interference from downlink signal of adjacent cells PN
: Noise floor of the receiver
Downlink Interference Analysis z
Receiver noise floor: PN
PN = 10 log( K * T * W ) + NF
For commercial UE, the typical value is -101dBm/3.84MHZ
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
K: Boltzmann constant, 1.38×10-23J/K
z
T: Temperature in Kelvin, normal temperature: 290 K
z
W: Signal bandwidth, WCDMA signal bandwidth 3.84MHz
z
Nth = 10log(K*T*W)=-108dBm/3.84MHz
z
NF: For commercial UE, typical value is 7dB.
Page34
Downlink Interference Analysis z
I own :Interference from downlink signal of this cell
The downlink users are identified with the mutually orthogonal OVSF codes. In the static propagation conditions without multipath, no mutual interference exists.
In case of multi-path propagation, certain energy will be detected by the RAKE receiver, and become interference
α signals. We define the non-orthogonal factor phenomenon:
( Iown) j = α × PTX
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
to describe this
Page35
α Compared to the uplink load equation, the most important new parameter is
,
which represents the non-orthogonality factor in the downlink. WCDMA employs orthogonal codes in the downlink to separate users, and without any multi-path propagation the orthogonality remains when the base station signal is received by the mobile. However, if there is sufficient delay spread in the radio channel, the mobile will see part of the base station signal as multiple access interference. The orthogonality of 1 corresponds to perfectly orthogonal users. Typically, the nonorthogonality is between 0.1 and 0.6 in multi-path channels. z
Where:
PTX is the actual transmission power of NodeB
Downlink Interference Analysis z
I other : Interference from the downlink signal of adjacent cell
The transmitting signal of the adjacent cell NodeB will cause interference to the users in the current cell. Since the scrambling codes of users are different, such interference is non-orthogonal
Hence we obtain:
( Iother ) j = f × PTX
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Where:
f
PTX is the actual transmission power of NodeB
is Adjacent cell interference factor
Page36
Downlink Interference Analysis z
Ec/Io for User j is:
Pj (
Pj Ec 10CL /10 )j = = ( CL + PN ) / 10 (α + f ) × PTX Io ( α + f ) × P + 10 PN / 10 TX + 10 10CL /10
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page37
Where:
Pj is the transmission power of NodeB for User j
CL is Downlink Coupling Loss, is equals to:
CL = PL _ DL + Lf _ BS − Ga _ antenna + Lb + SFM NSHO + Lp
z
PL_DL: Downlink path loss
Lf_BS: cable loss of NodeB
Ga_antenna: Gain of UE antenna and NodeB antenna
Lb: Body loss
SFMNSHO: Slow fading margin without soft handover
Lp: Penetration loss
Therefore:
Pj 10CL /10
is the useful power received by user j
(α + f ) ×η DL _ Total × Pmax
10CL /10
is the interference from own cell and adjacent cell,
and it includes Iown and Iother
10 PN /10 is the noise floor of UE
Downlink Interference Analysis z
Under the ideal power control: ( Eb / No ) j 10
10 z
=(
Ec W 1 )j × × Io Rj ρ j
Then we can get: ( Eb / No ) j
10
10
Pj =
10( CL + PN ) /10 × ρ j × PTX × (α + f + ) PTX W / Rj
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Where:
W is the chip rate, which is 3.84Mcps
Rj is the bit rate of service.
ρ j is the activity factor.
Page38
Downlink Interference Analysis z
Define the downlink load factor for user j: ( Eb / No ) j
ηj = z
Pj Pmax
10 =
10
PTX 10( CL + PN ) /10 ) ×ρj × × (α + f + Pmax PTX W / Rj
Define the downlink load factor for the cell:
η DL =
PTX Pmax
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page39
The downlink load factor are defined in the transmitter side (NodeB).
Downlink Interference Analysis z
According to the above mentioned relationship, the noise will rise:
NoiseRise =
I total PN + I own + I other No + (α + f )× PMax ×η DL / CL = = PN PN PN
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page40
The NoiseRise is used in link budget to estimate the Interference Margin
Contents 1. Traffic Model 2. Interference Analysis 3. Capacity Dimensioning 4. CE Dimensioning 5. Network Dimensioning Flow
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page41
Capacity Dimensioning Flow Dimensioning Start
Assumed Subscribers Load per Connection of R99
CS Average Cell Load
CS Peak Cell Load (MDE)
PS Average Cell Load
HSPA Cell Load
Total Cell Load
No
=Target Cell Load? Yes Dimensioning End
Load cell −total _ UL = max{ Load CS − peak , Load CS − avg + Load PS − avg + Load HSUPA } Load cell −total _ DL = max{ Load CS − peak , Load CS − avg + Load PS − avg + Load HSDPA } + Load CCH Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
For UL, the load per connection of R99 is calculated by the following formula:
η j = (1 + f )× L j = (1 + f )×
1 1
1+
( EbvsNo)Avg _ j
10 z
10
⋅
W 1 ⋅ Rj ρ j
For DL, the load per connection of R99 is calculated by the following formula: ( Eb / No ) j
ηi = z
Page42
Pi = Pmax
10
10
PTX 10( CL + PN ) /10 × (α + f + ) Pmax PTX W / Rj
×ρj ×
Typical Value: ρ( j for AMR 12.2k is 0.67,f
ηUL is 0.65,
CCH is 20%, Channel model is TU3, DL CL isα135dB, transmission power is 43dBm) Load per User
Uplink
ηUL is 50%,
is 75%, load of
is 0.5, NodeB max
Downlink
AMR12.2k
1.19%
1.05%
CS64k
4.99%
5.81%
PS64k
4.77%
4.11%
PS128k
8.69%
8.03%
PS384k
21.35%
19.59%
Contents 3. Capacity Dimensioning 3.1 R99 Capacity Dimensioning 3.2 HSDPA Dimensioning
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page43
Capacity Dimensioning Differences GSM
WCDMA
z Hard blocking
z Soft blocking
z Capacity --- hardware dependent
z Capacity --- interference dependent
z Single service
z Multi services (CS&PS)
z Single GoS requirement
z Respective quality requirements of each service
z Capacity dimensioning ---ErlangB
z Capacity dimensioning --Multidimensional ErlangB
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page44
The GSM capacity is decided by the number of carriers, it is hard capacity. But WCDMA capacity is related to interference, coverage, channel condition, it is soft capacity.
z
z
The Erlang-B formula is only used for
Circuit switched services
Single service
Multidimensional ErlangB (MDE) is suitable for:
Multi service with different GoS
Different service will share the same resource.
Multidimensional ElangB Principle (1) z
Multidimensional ErlangB model is a Stochastic Knapsack Problem.
z
“Knapsack” means a system with fixed capacity, various objects arrive at the knapsack randomly and the states of multi-objects in the knapsack are stochastic process.
z
Then when various objects attempt to access in this system, how much is the blocking probability of every object? Calls arrival
Fixed capaciy
K classes of services Calls completion
Blocked calls Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page45
Multidimensional ErlangB is a public algorithm. Now Huawei selects it. Operators can use different algorithm to calculate the load.
Multidimensional ElangB Principle (2) z
Case Study: Two dimensional ErlangB Model
The size of service 2 is twice as that of service 1
C is the fixed capacity
n2
n2
n2 States Space
3
3
Blocking States of Class 1
C
Blocking States of Class 2
C
C
2
2
2
Ω
C-b1
C-b2
1
1
1
3
2
3
4
5
6
n1
1
1
2
3
4
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
5
6
n1
1
2
3
4
5
6
n1
Page46
z
b1:size of service 1, which means the resource required by service 1 .
z
b2:size of service 2, which means the resource required by service 2 .
z
b2=2*b1
z
n1: number of service 1 connection
z
n2: number of service 2 connection
z
The left graph describes all the states (blue dots) that satisfies: n1*b1+n2*b2throughput
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Cell average throughput
Page57
During the HSDPA capacity dimensioning procedure, we know the Cell Coverage Radius (obtained from the coverage planning) and Cell Average Throughput (obtained from the traffic model), and we want to get the HSDPA Power Allocation based on simulation.
Case Study z
z
Input parameters
Subscriber number per cell: 800
HSDPA Traffic model: 1200kbit per subs
HSDPA Retransmission rate: 10%
The power for HS-SCCH: 5%
Cell radius: 1km
HSDPA cell average throughput:
800 *1200 * (1 + 10%) = 293kbps 3600 z
The needed power for HS-DSCH including that for HS-SCCH is 18.38%
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page58
Case Study z
Uplink Total Load of the Cell :
CS Peak Load: 42.53%
CS&PS average load: 23.89%
Load cell −total _ UL = max{ Load CS − peak , Load CS − avg + Load PS − avg } = MAX ( 42 .53%, 23.89% ) = 42.53% z
Downlink Total Load of the Cell :
CS Peak Load: 42.33%
CS&PS average load: 27.82%
HSDPA load is 18.38%
CCH load: 20%
Load cell −total _ DL = max{ Load CS − peak , Load CS − avg + Load PS − avg + Load HSDPA } + Load CCH = MAX ( 42 .33%, 27 .82% + 18.38%) + 20% = 66.20% Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page59
Base on this capacity dimensioning result, we can check whether the cell load of the network is beyond the network target. If it is, we should adjust the cell radius.
Contents 1. Traffic Model 2. Interference Analysis 3. Capacity Dimensioning 4. CE Dimensioning 5. Network Dimensioning Flow
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page60
Overview z
Definition of a CE:
A Channel Element is the base band resource required in the Node-B to provide capacity for one voice channel, including control plane signaling, compressed mode, transmit diversity and softer handover.
z
NodeB Channel Element Capacity
One BBU3900
UL 1,536 CEs with full configuration
DL 1,536 CEs with full configuration
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page61
Due the technical features of the WCDMA, compared with the 2G systems such as GSM, the RNC and Node B present enormous capacity. For example, for the fully configured NodeB, the number of channels of one carrier is 128, which is more than 10 times of that supported by a TRX of GSM. One uplink processing unit of our NODEB has the processing capacity of 128 12.2kbps voice channels. One 3*1 WCDMA BTS is equivalent to the GSM sites of one S10/10/10. At the beginning of the WCDMA network construction, so high a capacity is not a necessity, and only a portion of it is required (e.g., 10%). If we offer the quotation based on the maximum hardware channel capacity of TRX like the GSM, it will make the operators incur enormous cost and mismatch the user quantity. To reduce the initial investment, the operator is bound to pay the equipment price to the supplier according to the actual use capacity, and, subsequently, pay more equipment prices with the increase of the user quantity. This way, the operator will reduce the initial investment and mitigate the risks.
Huawei Channel Elements Features z
Channel Elements pooled in one NodeB
z
No need extra R99 CE resource for CCH
reserved CE resource for CCH
z
No need extra CE resource for TX diversity
z
No need extra CE resource for Compressed Mode
reserved resources for Compressed Mode
z
No need extra CE resource for Softer HO
z
HSDPA does not occupy R99 CE resource
separate module for HSDPA
z
HSUPA shares CE resource with R99 services
z
No additional CE resource for AGCH RGCH and HICH
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page62
Softer HO CE: 3900 series NodeB doesn’t need extra CE resource, but 3800 series
NodeB needs extra CE resource z
HSUPA shares CE resource with R99 services: that means the HSUPA E-DCH shares CE resource with R99 services
CE Dimensioning Flow Dimensioning Start --Subscribers per NodeB --Traffic model
CS Average CE
CS Peak CE
(MDE)
PS Average CE
HSPA CE
Channel Elements per NodeB
Dimensioning End
CEUL _ Total = Max (CE CS _ Peak _ UL , CE CS _ Average _ UL + CE PS _ UL + CE A _ UL + CE HSUPA )
CE DL _ Total = Max (CE CS _ Peak _ DL , CE CS _ Average _ DL + CE PS _ DL + CE A _ DL ) Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page63
CE Mappings for R99 Bearers Channel Elements Mapping for R99 Bearers Bearer
Uplink
Downlink
AMR12.2k
1
1
CS64k
3
2
PS64k
3
2
PS128k
5
4
PS144k
5
4
PS384k
10
8
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
Page64
The mapping relationship of Channel Elements consumption for each bearer is based on Uplink 2-way diversity
z
z
In the case of uplink 4-way diversity, the CE consumption is shown below:
Bearers
CE (4-way diversity)
AMR12.2k
2
CS64k
4
PS64k
4
PS128k
8
PS384k
16
Detailed and recently updated data should be referred to the newest issued notice of "UMTS RAN Product Specificaiton".
R99 CE Dimensioning Principle z
Peak CE occupied by CS can be obtained through multidimensional ErlangB algorithm
z
Average CE needed by CS and PS depend on the traffic of each service, i.e.
z
CE resource shared among each service
Average CE = Traffic * CE Factor
CS Peak CE
CE occupied by PS and HSPA
CS Average CE
Multdimensional ErlangB Model AM R1 2 .2 k
......
CE
Total CE
CE Resources
CE occupied by CS
6 CS Time Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
z
4k
Page65
The CE dimensioning principle is similar with capacity dimensioning.
HSDPA CE Dimensioning z
In uplink, no CE consumption for HS-DPCCH if corresponding UL DCH channel exists
z
In uplink, CE consumed by one A-DCH depends on its bearing rate
z
In downlink, A-DCH is treated as R99 DCH.
z
No additional CE needed for HS-DSCH and HS-SCCH Associated Dedicated Channels
One HSDPA link need one A-DCH in uplink and downlink respectively
HS -D S
CH HS -S CC HS H -D PC CH
Site 1
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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Site 2
Page66
HSDPA channels doesn’t occupy R99 CE resource, but we should calculate the A-DCH CE.
CE Mappings for HSDPA Bearers HSDPA Channel Elements Consumption Traffic
Uplink
Downlink
---
0 CE
HS-DPCCH
0 CE
---
UL A-DCH (DPCCH)
3 CE
---
DL A-DCH (DPCCH)
---
1 CE
HSDPA Traffic
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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Page67
HSDPA Traffic:
Separate dedicated module processing HSDPA Traffic so HSDPA traffic does not occupy any R99 CE resource.
z
HS-DSCH and HS-SCCH does not affect base band capacity for R99 services.
HS-DPCCH
HS-DPCCH doesnot consume any R99 Channel Element since its base band resource is reserved in BBU module.
z
UL A-DCH (DPCCH)
PS64k is recommended to bear uplink user data, TCP acknowledgement and signaling.
z
One PS64k consumes 3 CE in uplink.
DL A-DCH (DPCCH)
A-DCH bears DL signaling control.
A-DCH can be beared on HSDPA since RAN10.0.
Case Study (1) z
Input Parameters
Subscribers number per NodeB: 2000 Overhead of SHO: 30%
UL
DL
AMR12.2k (Erl)
0.02
0.02
GoS 2%
0.001
0.001
2%
PS64k (kbit)
50
100
N/A
PS128k (kbit)
0
80
N/A
HSPA (kbit)
0
1200
N/A
CS64k (Erl)
R99 PS traffic burst: 20%
Retransmission rate of R99 PS: 5%
PS Channel element utilization rate: 0.7
Average throughput requirement per user of HSDPA: 400kbps
HSDPA traffic burst is 25%
Retransmission rate of HSDPA is 10%
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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Traffic Model
Page68
In this case, the R99 traffic model includes the traffic of HSDPA UL A-DCH. That means 50kbits for UL PS64k includes the R99 UL DCH and HSDPA UL A-DCH.
Case Study (2) z
Uplink CE Dimensioning
z
AMR12.2:
AMR12.2:
Traffic =0.02*2000*(1+30%) = 52Erl
Traffic =0.02*2000*(1+30%) = 52Erl
Peak CE =ErlangB(52,0.02)*1= 63 CE
Peak CE =ErlangB(52,0.02)*1 = 63CE
Average CE =52*1=52 CE
Average CE =52*1=52CE
CS64:
Traffic of VP:
Traffic =0.001*2000*(1+30%) = 2.6Erl
Traffic =0.001*2000*(1+30%) = 2.6Erl
Peak CE =ErlangB(2.6,0.02)*3 = 21 CE
Peak CE =ErlangB(2.6,0.02)*2 =14CE
Average CE =2.6*3=9 CE
Average CE =2.6*2=6CE
Total peak CE for CS: 80CE
Total peak CE for CS: 74CE
Total average CE for CS: 52+9=61CE
Total average CE for CS: 52+6=58CE
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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Page69
Different with capacity dimensioning, the UL CE dimensioning should consider the soft handover.
z
Downlink CE Dimensioning
For the peak CE, we should use MDE to calculate.
Case Study (3) z
Uplink CE Dimensioning
CE for PS64k: 2000 * 50 * 3 * (1 + 30%)* (1 + 20%)* (1 + 5%) = 4CE 64 * 0.7 * 3600
Total CE for R99 PS services: 4CE
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Downlink CE Dimensioning
CE for PS64k: 2000 *100 * 2 * (1 + 30%) * (1 + 20%) * (1 + 5%) = 4CE 64 * 0.7 * 3600
CE for PS128k: 2000 * 80 * 4 * (1 + 30%) * (1 + 20%) * (1 + 5%) = 4CE 128 * 0.7 * 3600
Total CE for R99 PS services: 4+4=8CE CE for HSDPA A-DCH: 2000 *1200 *1* (1 + 25%) * (1 + 10%) = 3CE 400 * 3600
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
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Page70
In this case, the R99 traffic model includes the traffic of HSDPA UL A-DCH, therefore it is no need to calculate the HSDPA UL CE
z
For the HSDPA DL A-DCH CE, strictly speaking, it can perform soft handover. But usually the CE requirement is low, so in Huawei strategy, the soft handover is not considered.
Case Study (4) z
Uplink CE Dimensioning
z
Downlink CE Dimensioning
Total CE
Total CE
CEUL _ Total = Max(CECS _ Peak _ UL ,
CE DL _ Total = Max( CECS _ Peak _ DL ,
CECS _ Average _ UL + CE PS _ Average _ UL )
CECS _ Average _ DL + CE PS _ DL + CE A _ DL )
= MAX (80, 61 + 4) = 80CE
= Max(74, 58 + 8 + 3) = 74 CE
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page71
Contents 1. Traffic Model 2. Interference Analysis 3. Capacity Dimensioning 4. CE Dimensioning 5. Network Dimensioning Flow
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page72
Network Dimensioning Flow start Coverage Requirement
UL/DL Link Budget Cell Radius=Min (RUL, RDL)
Capacity Requirement
UL/DL Capacity Dimensioning
Satisfy Capacity Requirement?
No
Yes CE Dimensioning Output NodeB Amount/ NodeB Configuration End Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Page73
Adjust Carrier/NodeB
Thank you www.huawei.com
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