Optimal Tradeoff Between Transmission Rate and Packet Duration in Wireless Ad Hoc Networks

This paper considers the tradeoff between bursty and continuous transmissions in wireless ad hoc networks. In our network model, packets belonging to specific transmitters arrive randomly in space and time according to a 3-D Poisson point process, and are then transmitted to their intended destinations using a fully-distributed MAC protocol (ALOHA or CSMA). Stochastic SINR measurements are used to determine whether or not a packet has been received successfully. The objective of this work is to maximize the probability of successful transmissions by optimizing the transmission rate and duration of packets. Approximate analytical expressions are derived for the outage probability of ALOHA and CSMA, and their performances are evaluated. The optimal spectral efficiency and packet duration of ALOHA is found analytically, and that of CSMA is obtained through simulations. CSMA is shown to yield the best performance both in terms of minimum achievable outage probability and the corresponding spectral efficiency.