Transmission capacity of CDMA ad hoc networks employing successive interference cancellation

Abstract

Upper and lower bounds on the transmission capacity of direct-sequence CDMA wireless ad hoc networks are derived. The transmission capacity is a stochastic measure of the allowable number of transmissions per unit area, and is a generalization of previous measures of ad hoc network capacity. Successive interference cancellation (SIC) is attractive for DS-CDMA ad hoc networks since the dominant nearby interferers can be cancelled. Our closed-form results cleanly summarize the dependence of ad hoc network capacity on pathloss, spreading, outage probability, and interference cancellation accuracy. Other multiple access schemes, such as CSMA and DS-CDMA without SIC, are special cases. Perfect interference cancellation increases transmission capacity by nearly two orders of magnitude. Furthermore, cancelling just the strongest interferer generally gives the majority of the capacity gain, so the latency and complexity cost of SIC should be negligible.