On the performance of wireless ad hoc networks using bandwidth partitioning

We consider an hoc network where nodes are assumed to be distributed uniformly in space, according to a 2-D Poisson point process (PPP), and packets arrive at each transmitter according to a 1-D temporal PPP. The system bandwidth is divided into multiple subbands, and each transmitter selects one subband to transmit over. The channel access is governed by ALOHA or carrier sensing multiple access (CSMA) MAC protocols, in their various incarnations. The main system objective is correct reception of packets, and thus the analysis is performed in terms of outage probability, which is defined as the probability that the transmission rate required for correct reception of a packet exceeds the channel capacity, and in terms of throughput, that is the amount of information correctly received at the receivers. The performance of these protocols is derived both in the absence and presence of fading, and used to compare the different MAC protocols. The optimal number of subbands maximizing the throughput is obtained analytically for ALOHA and through simulations for CSMA, illustrating how the ’right’ number of subbands can improve the performance, compared to a random number of subbands. Furthermore, in the case of CSMA, sensing across all subbands is introduced and shown to provide additional performance gain.