Final Report of EE359 Class Project Throughput and Delay in Wireless Ad Hoc Networks

Network throughput and packet delay are the two most important parameters to evaluate the performance of wireless ad hoc networks. Generally it is difficult to achieve both high throughput and low packet delay. In this project, the objective is to achieve high throughput while keeping the packet delay under certain threshold. We will first look at the throughput capacity theoretically in mobile ad hoc networks. Gupta and Kumar [1] show the average available throughput per node decreases as n / 1 or n n lg / 1 in a static ad hoc network, where n is the number of nodes. That means, the total network capacity increases as at most n . Furthermore, Grossglauser and Tse [2] show mobility can improve the capacity. However, delay is not guaranteed in their schemes. Actually delay will increase due to possibly more hops or queueing in order to increase the throughput. Bansal and Liu [3] show it is possible to achieve close-to optimal capacity while keeping the delay small. In their model, each sender can achieve an average throughput of n n n m W c 3 log ) , min( , where W is the maximum available bandwidth, with the packet delay at most v d 2 , where d is the diameter of the network and v is the velocity of the mobile nodes. Based on this fact, the authors propose a routing algorithm that achieves the objective through exploiting the patterns in the mobility of nodes. The throughput achieved by this algorithm is only a poly-logarithmic factor off from the optimal.