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Performance Evaluation of LEACH Protocol in Wireless Network
« on: February 18, 2012, 02:28:55 am »
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Author : M.Shankar, Dr.M.Sridar, Dr.M.Rajani, Dr.Soma V.Chetty
International Journal of Scientific & Engineering Research Volume 3, Issue 1, January-2012
ISSN 2229-5518
Download Full Paper : PDF

Abstract—Wireless micro sensor networks lend themselves to trade-offs in energy and quality. By ensuring that the system operates at a minimum energy for each quality point, the system can achieve both flexibility and energy efficiency, allowing the end-user to maximize system lifetime. Simulation results show that the proposed adaptive clustering protocol effectively produces optimal energy consumption for the wireless sensor networks, and resulting in an extension of life time for the network. The preparation phase is performed only once before the set-up phase of the first round. The processes of following set-up and steady-state phases in every round are the same as LEACH. Simulations show that LEACH can achieve as much as a factor of 8 reductions in energy dissipation compared with conventional routing protocols. In addition, LEACH is able to distribute energy dissipation evenly throughout the sensors, doubling the useful system lifetime for the networks we simulated

Index Terms— Cluster, energy efficiency, LEACH protocol, network lifetime, wireless sensor networks
 
1   INTRODUCTION
A number of technologies currently exist to provide users with wireless connectivity. The challenges in the hierarchy of: detecting the relevant quantities, monitoring and collecting the data, assessing and evaluating the information, formulating meaningful user displays, and performing decision-making and alarm functions are enormous. The information needed by smart environments is provided by Wireless Sensor Networks [1], which are responsible for sensing as well as for the first stages of the processing hierarchy. The security has become a big task in wired and wireless networks. Sensor networks are self-organized networks, which makes them suitable for dangerous and harmful situations, but at the same time makes them easy targets for attack. For this reason we should apply some level of security so that it will be difficult to be attacked, especially when they are used in critical applications. Wireless Sensor Networks (WSNs) are special kinds [2, 3, 4, 5] of Ad hoc networks that became one of the most interesting areas for researchers to study. The most important property that affects these types of network is the limitation of the available resources, especially the energy. This organization provides some energy saving, and that was the main idea for proposing this organization.
LEACH (Low Energy Adaptive Clustering Hierarchy) added another interesting issue to this kind of network.  By analyzing the advantages and dis-advantages of conventional routing protocols, LEACH (Low- Energy Adaptive Clustering

Hierarchy) Protocol was developed a clustering based protocol that minimizes energy dissipation in sensor networks. This work focuses on LEACH (Low-Energy Adaptive Clustering Hierarchy), a communication protocol for micro sensor networks. LEACH collects data from distributed micro sensors and transmits it to a base station. LEACH Low-Energy Adaptive Clustering Hierarchy (or LEACH) was one of the first major improvements on conventional clustering approaches in wireless sensor networks. Conventional approaches algorithms such as MTE (Minimum-Transmission-Energy) or direct-transmission do not lead to even energy dissipation throughout a network. LEACH provides a balancing of energy usage by random rotation of cluster heads. The algorithm is also organized in such a manner that data-fusion can be used to reduce the amount of data transmission.

Figure1. Cluster organization for sensor networks

Types of Broadcast

1. Probalistic
1. Distance Mode
2. Location Mode
3. Counters Mode

2. Deterministic

    1. Self – Pruning
    2. Scalable broadcasting
    3. Ad hoc broadcasting
    4. Cluster based
    5. Simple flooding

The development of clustered sensor networks has recently been shown to decrease system delay, save energy while performing data aggregation and increase system throughput. These are strong motivational points behind selecting LEACH as the baseline protocol for the analytical study. Also LEACH has a few but very significant disadvantages like it assumes all the nodes to have same energy, which is not the case always in real-time problems, its cannot be applied for mobile nodes, failure of cluster-heads creates a lot of problems and it doesn’t take into account that the systems might have multiple base stations. Low Energy Adaptive Clustering Hierarchy (LEACH) is an energy-efficient hierarchical-based routing protocol. Our prime focus was on the analysis of LEACH based upon certain parameters like network lifetime, stability period, etc. and also the effect of selective forwarding attack and degree of hetero- geneity on LEACH protocol.

2   LEACH PROTOCOL
LEACH (Low Energy Adaptive Clustering Hierar-chy) is a hierarchical-based routing protocol which uses random rotation of the nodes required to be the cluster-heads to evenly distribute energy consumption in the network. Sensor network protocols are quite simple and hence are very susceptible to attacks like Sinkhole attack, Selective forwarding, Sybil attack, Wormholes, HELLO flood attack, Acknowledgement spoofing, altering, replaying routing information. For example, Selective forwarding and HELLO flood attack affects networks with clustering based protocols like LEACH.

2.1 Description
Heinzelman introduced a hierarchical clustering algorithm for sensor networks, called Low Energy Adaptive Clustering Hierarchy (LEACH). LEACH arranges the nodes in the network into small clusters and chooses one of them as the cluster-head. Node first senses its target and then sends the relevant information to its cluster-head. Then the cluster head aggregates and compresses the information received from all the nodes and sends it to the base station. Low Energy Adaptive Clustering Hierarchy (LEACH) is the first hierarchical cluster-based routing protocol for wireless sensor network which partitions the nodes where these data is needed using CDMA (Code division multiple access). Remaining nodes are cluster members this protocol is divided into rounds; each round consists of two phases.

Set-up Phase
(1) Advertisement Phase
(2) Cluster Set-up Phase

Steady Phase
(1) Schedule Creation
(2) Data Transmission
Set-up Phase
Each node decides independent of other nodes if it will become a CH or not. This decision takes into account when the node served as a CH for the last time (the node that hasn't been a CH for long time is more likely to elect itself than nodes that have been a CH recently). This is done according to a threshold value, T (n). The threshold value depends upon the desired percentage to become a cluster-head- p, the current round r, and the set of nodes that have not become the cluster-head in the last 1/p rounds, which is denoted by G. Based on all messages received within the cluster, the CH creates a TDMA schedule, pick a CSMA code randomly, and broadcast the TDMA table to cluster members every node wanting to be the cluster-head chooses a value, between 0 and 1. If this random number is less than the threshold value, T (n), then the node becomes the cluster- head for the current round. Then each elected CH broadcasts an advertisement message to the rest of the nodes in the network to invite them to join their clusters. Based upon the strength of the advertisement signal, the non-cluster head nodes decide to join the clusters. In the set-up phase, the cluster head nodes are randomly selected from all the sensor nodes and several clusters are constructed dynamically 

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