Speaker: Francois Bacelli (ENS/INRIA, Paris)

Title: On Optimizing CSMA for Wide Area Ad Hoc Networks

Abstract:

Recent deployments of data-rich smart phones has provided a fresh impetus for designing, deploying and understanding the performance of wide area ad-hoc networks. The most popular medium access mechanism for such ad hoc networks is CSMA/CA with RTS/CTS. In this paper, using tools from stochastic geometry, we study and optimize the throughput performance of such networks. We show that in ad-hoc networks enabled with SIR based scheduling, a simple modification to the transmit power level - setting it to be inversely proportional to the square root of the link gain - leads to large improvements in network throughput. This simple power-level selection is optimal over the class of all "local" transmit power selection strategies when channels are stationary, and further is at most a factor of two away from optimality in the fading case. Using stochastic geometric techniques, we also provide analytical expressions for the medium access probability in different scenarios.

This is joint work with Junyi Li, Thomas Richardson, Sanjay Shakkottai, Sundar Subramanian and Xinzhou Wu.