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Page 2 Lecture Notes in Computer Science 2865 Edited by G. Goos ...

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78 R. Shah and N.C. Hutch<strong>in</strong>sonTable 1. AODV parameter values used <strong>in</strong> the simulationsParameterValueEXPANDING RING SEARCH ONTTL START 7TTL THRESHOLD 7NETWORK DIAMETER 30RREQ RETRIES 1AODV LOCAL REPAIR OFFAODV LINK LAYER DETECTION OFFHELLO INTERVAL 1ALLOWED HELLO LOSS 34.1 Mobility ModelThe Random Way Po<strong>in</strong>t model is the most widely used mobility model <strong>in</strong> test<strong>in</strong>gprotocols <strong>in</strong> mobile ad-hoc networks. We have made two modifications to theRandom Way Po<strong>in</strong>t model to make it more practical.Random Way Po<strong>in</strong>t Model. The Random Way Po<strong>in</strong>t Model was first described<strong>in</strong> [3], s<strong>in</strong>ce then it has been widely used to test MANET protocols <strong>in</strong>simulated environments. In this model nodes move around <strong>in</strong> a “room”. Eachnode starts from an <strong>in</strong>itial position selected randomly from with<strong>in</strong> the simulatedarea. As the simulation progresses, each node pauses at its current position for aconstant period of time and then randomly chooses a dest<strong>in</strong>ation location fromwith<strong>in</strong> the simulated region and moves there <strong>by</strong> select<strong>in</strong>g a random speed uniformlyfrom the <strong>in</strong>terval (0,V], where V is the maximum speed with which anode can move.Modifications <strong>in</strong> Random Way Po<strong>in</strong>t Model. We believe that the applicationsdeveloped for Mobile Ad Hoc environments will be mostly <strong>in</strong>teractiveand therefore people us<strong>in</strong>g them would be walk<strong>in</strong>g or stroll<strong>in</strong>g. Studies [10] haveshown that the normal walk<strong>in</strong>g speed of an adult human be<strong>in</strong>g is around 1.5m/s. We also consider the possibility of vehicles (particularly <strong>in</strong> the disasterrelief scenarios outl<strong>in</strong>ed <strong>in</strong> section 1) mov<strong>in</strong>g at a slow speed. [13] shows thatselect<strong>in</strong>g a m<strong>in</strong>imum speed greater than zero for mobile nodes is necessary toatta<strong>in</strong> a mean<strong>in</strong>gful steady state. Therefore we choose node speed from a normaldistribution with mean speed set to 1.5 m/s. The m<strong>in</strong>imum speed is set to 0.4m/s while the maximum speed is set to 5.0 m/s.The Random Way Po<strong>in</strong>t Model assumes uniform distribution of nodes, whichis quite “unrealistic”. The density of nodes would vary a lot <strong>in</strong> any of the scenariosdescribed <strong>in</strong> section 1. There would be some hot-spots where nodes areclustered. In a disaster relief scenario these hot-spots could be sites where reliefand rescue work is be<strong>in</strong>g carried out; on a beach these could be particularlyscenic po<strong>in</strong>ts, snack bars, or volleyball courts; <strong>in</strong> a military zone these could be

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