Transmission capacity: applying stochastic geometry to uncoordinated ad hoc networks

This paper summarizes recent contributions on the transmission capacity of ad hoc networks. Although it is notoriously difficult to derive general end-to-end capacity results for ad hoc networks, the transmission capacity framework allows for quantification of achievable single-hop rates by focusing on a simplified physical/MAC-layer model. By using stochastic geometry to quantify the multi-user interference in the network, the relationship between the spatial density and success probability of transmissions in the network can be determined. The basic model and analytical tools are first discussed, followed by summaries of results that capture the effect of important network parameters such as the fading distribution and path loss exponent. Design choices, including direct-sequence versus frequency-hopping spread spectrum, the optimal number of sub-bands under a rate constraint, interference cancellation, an optimum channel-strength threshold for scheduling, power control exponent selection, and the use of multiple antennas are investigated. The paper closes by discussing shortcomings in the model as well as future directions.