OPTIMIZATION OF LOCATION AWARE ROUTING PROTOCOLS FORB WIRELESS ADHOC TACTICAL NETWORKS

Abstract

Mobile Adhoc Network (MANET) is a wireless technique which does not require any pre-existing infrastructure to function. It only requires wireless devices with sufficient battery to build the infrastructure dynamically by using any of available Adhoc routing protocols. MANET comprises three types of nodes i.e. source node, destination node and forwarding nodes also called routing nodes. Routes between source and destination are established as and when needed using on demand approach i.e. reactive approach. Therefore when a route is needed source node broadcasts ”send request” packet to the destination node with the help of intermediate nodes called forwarding nodes and when a route is found/established, source node sends data via intermediate/forwarding nodes to this destination node. But due to high node mobility and frequent change in routes, data transmission may break often hence routes are recreated and updated accordingly by using any of the Adhoc routing protocol. There are many MANET approaches available e.g. DSDV, DSR, OLSR, AODV, ABR, ZRP but these protocols are used depending on the nature of situation. Protocol we have used in our thesis is Adhoc on Demand Distance Vector Routing (AODV) which is a reactive protocol i.e. it creates routes as and when required. AODV protocol was developed by Nokia Research Center, University of California, Santa Barbara and University of Cincinnati by C. Perkins, E. Belding-Royer and C. Das. Algorithm of AODV states that when source node needs route to destination it broadcasts send request packet to all the nodes present in given geographic region and broadcasting method used is expanding ring search. Even when route breaks or invalidates, AODV first checks route buffer to see if existing route could be used or not. If either existing route is stale or tovi pography is changed due to mobility then again AODV uses broadcasting to discover the requested route. That means each time, when route is needed, the route request packet is broadcasted to all nodes which unnecessarily uses the bandwidth and processing at each node causing power bottleneck to arise. Therefore our thesis is focused on the optimization of AODV protocol by restricting packet broadcasting to conserve power of nodes. For this purpose, we have used Global Positioning System. By knowing coordinates of the nodes, our algorithm targets only that subset of nodes which are directly participating in route establishment. This modified algorithm limits route request packets which results drastic reduction in packet broadcasting and conserves power. Hence control packets are reduced whereas data transmission increases which also increases performance. To simulate the algorithm we have used NS2 in Linux based platform. NS2 is basically mixture of TCL and C++ whereas OTCL provides linkage between TCL and C++. Backend code is implemented in C++ language whereas TCL language is used to create front end layout by defining number of nodes, their traffic pattern and their parameters e.g. transmission range, battery power etc. In the end, results of modified AODV are compared with traditional AODV and DSR.