Data Structures in Wireless Sensor Networks
Buse Türkoğlu#1
#Computer Engineering, Yaşar University
Yaşar University, Bornova - İzmir, Turkey
[email protected]
Abstract— This document gives information about data structures in wireless sensor networks and OBD (on-board-diagnostics database in vehicles).
Keywords— Data structures, OBD, Wireless Sensor Network, Network
Introduction
This document gives information about architecture and data structure of wireless sensor networks, why and where we use this system in our lives. Then we talk about monitoring and transferring data with using OBD- II in vehicles.
Wireless Sensor Network
A wireless sensor network (WSN) distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound, pressure, etc. and to cooperatively pass their data through the network to a main location [1].
Fig.1 Simple explanation of WSN
Figure 1 shows connection of systems between mobile devices or computers with using WSN. Whole data sends to main device to control system.
Different data structures
In recent years WSN have been used for different applications such as environmental monitoring, military. It uses many sensor nodes to collect and send data to base station. Transmission of data to the base station consumes energy and produces traffic, because process is run in a large network. Data aggregation was proposed in order to reduce redundancy in data transformation and traffic. The most popular communication protocol is cluster based data aggregation. Clustering causes energy balance, but sometimes energy consumption is not efficient due to the long distance between cluster heads and base station. In another communication protocol, which is based on a tree construction, because of the short distance between the sensors, energy consumption is low. In this data aggregation approach, since each sensor node is considered as one of the vertices of a tree, the depth of tree is usually high.
Tree Based Data Aggregation
In tree based data aggregation base stations are roots and source nodes are considered as leaves. Each node has a parent node to forward its data. Flow of data starts from leaves nodes up to the base station and aggregation is done by parent nodes.
Cluster Based Data Aggregation
Clustering is a fundamental solution to energy efficiency in sensor networks. Sensor nodes are organized into clusters, with each cluster having a "cluster head" as the manager. Communication within a cluster must go through the cluster head, which is then forwarded to a neighboring cluster head until it reaches the base station. LEACH is one of the primary and popular clustering algorithms. The operation of LEACH is divided into rounds. Each round begins with a set-up phase when the clusters are organized, followed by a steady-state phase when data are transferred from the nodes to the cluster head and to the base station. Nodes within a cluster that have more energy are delegated as cluster heads more often than nodes with less energy.
Cluster Based and Tree Based Power Efficient Data Collection and Aggregation Protocol (CTPEDCA): This method provides an energy efficient mechanism for data transmission between cluster heads. A cluster head with maximum residual energy is selected (CH0) as the root. The disadvantage of this method is a ruin tree in which CH0 does not have enough energy and this method is used when the base station is too far.
Hybrid Structure
In this approach, the base station forms the primal clusters and these clusters do not change much because all sensor nodes are immobile, whereas the selected cluster head in the same cluster may be different in each round. For a node to be a cluster head, it has to be located at the center of a cluster. Once a node is selected to be a cluster head, it broadcasts a message in the network and invites the other nodes to join its cluster. When the cluster head receives the join message from its neighbor node, it assigns the node a time slot to transmit data. When the first round is over and the primal cluster topology is formed, the base station is no longer responsible for selecting the cluster head. Base station will collect the information that cluster head had labeled in each cluster and build path in minimum spanning tree to compute the tree path.
obd- II
On-Board Diagnostics or "OBD" is a computer based control & monitoring system built in 1996. OBD systems are design to monitor the performance of vehicles by using wireless sensor network.
All cars have OBD-II systems since January 1, 1996. You can easily connect this system with using Bluetooth or wireless. System reaches the data converting signals from sensors. And finally signals, notifications, or alerts come to your phone or PC.
Fig.2 Example of OBD- II System
This figure shows us the architecture and connection with using network. We can easily connect the hardware by using Bluetooth or USB and monitor the performance of our vehicle.
Fig.3 Hardware of an OBD- II System
OBD has many advantages for different reasons such as;
OBD serves as an early warning system that alerts you to the potential need for vehicle.
OBD is a tool that assist in the service repair of vehicles by providing a simple quick and effective way to pinpoint problems by retrieving vehicle diagnostics from the OBD systems.
OBD systems play important role where vehicle inspection and maintenance programs are required.
Conclusıons
In this document we talk about data structures of wireless sensor networks, how we use this system in daily life and what are the benefits of this systems. In general, we use this networking system to monitor industrial and biomedical processes, building climate control, air pollution detection control, smart lighting and so on. OBD- II is one of the applications we use in vehicle monitor and control system.
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