On throughput capacity of large-scale ad hoc networks with realistic buffer constraint

The problem of determining the throughput capacity of an ad hoc network is addressed. Previous studies mainly focused on the infinite buffer scenario, however, in this paper we consider a large-scale ad hoc network with a scalable traffic model, where each node has a buffer of size B packets, and explore its corresponding per node throughput performance. We first model each node as a G/G/1/B queuing system which incorporates the important wireless interference and medium access contention. With the help of this queuing model, we then explore the properties of the throughput upper bound for all scheduling schemes. Based on these properties, we further develop an analytical approach to derive the expressions of per node throughput capacity for the concerned buffer-limited ad hoc network. The results show that the cumulative effect of packet loss due to the per hop buffer overflowing will degrade the throughput performance, and the degradation is inversely proportional to the buffer size. Finally, we provide the specific scheduling schemes which enable the per node throughput to approach its upper bound, under both symmetrical and unsymmetrical network topologies.