Probability Based Improved Broadcasting for AODV Routing

Protocol

ABSTRACT

Broadcasting is an inevitable operation of route discovery Mobile Adhoc Network (MANET). Though the broadcast by flooding is simple but inefficient and results in redundant message relays. This in turn over use limited network resources like channel bandwidth and node energy. The alleviated broadcasting with energy saving technique is necessary for the efficient route discovery and to improve network lifetime. In this paper Probability based Broadcasting technique for routing protocol is proposed to trim down flooding problem. It uses node s remaining energy strength and threshold random delay to generate rebroadcast probability dynamically for the efficient broadcasting in route discovery. This technique is analyzed over reactive Adhoc On-Demand Distance Vector (AODV) protocol. The route request (RREQ) packet of AODV is modified to gather energy information of nodes.

The performance of modified protocol is analyzed over broadcast packets sent and End-to-End Delay using ns2 simulator. Simulation results are observed and found that redundant transmission are to reduced by 19 to 28 percent and hence improve network performance.

Table of Contents

ABSTRACTii

Introduction1

Routing and Broadcasting2

Modified RREQ Packet6

Methodology of Probability based Broadcasting technique8

Performance Analysis9

Results and Analysis10

Broadcast Packets Sent10

Broadcast Packets Overhead Saved11

Average End-to-End Delay12

Improved End-to-End Delays13

Reachability13

Conclusion14

References16

Probability Based Improved Broadcasting for AODV Routing

Introduction

Mobile ad hoc network (MANET) is an autonomous, self organized, decentralized, power constrained system of mobile nodes (also called routers), which are connected by wireless links forming an arbitrary graph. The battery driven nodes are free to move randomly and organize themselves freely and so network topology may change rapidly and unpredictably as shown in figure 1. Due to the limited transmission range of wireless interfaces, in most cases communication has to be relayed over intermediate nodes and so each node not only acts as host but also as a router to forward the packets/messages. The simplicity in deployment and easy use of wireless adhoc network has come at the cost of many challenges. Some of them are: limited wireless transmission range, packet losses due to transmission errors, Mobility-induced route changes, mobility-induced packet losses, battery constraints, security hazard, broadcast nature of the wireless medium etc. These challenges become vital to handle with the high mobility and density of routers(Abdalla, 2009).

The easy and fast establishment of wireless adhoc network without any central infrastructure offer many applications especially in areas where temporary network is required or establishing of fixed network is not possible. For example, these environments are: Personnel area network (e.g. Class rooms), Military environment (e.g. Battle ground), Civilian environment (e.g. Cabs) and Emergency operations (e.g. Flooded area) etc. The broadcast of route request is necessary for route discovery in adhoc networks (Benoit, 2010). Traditionally, a straight-forward and simple approach to perform broadcast is flooding. It consists of diffusion of route request message from source node to all the neighbor nodes in the network. A host (barring destination node), on receiving a broadcast message for the first time, has the obligation to rebroadcast the message.

The flooding may result in up to |V|-1 transmission of the route request message except destination in a network ...