User-aware rate adaptive control for IEEE 802.11-based ad hoc networks

The existing rate adaptive control schemes for ad hoc networks just adapt to the time variation of the fading channels but not to the variation of the network congestion level. In this paper, we propose a user-aware rate adaptive control (UARAC) scheme for IEEE 802.11-based ad hoc networks, which exploits not only time diversity but also multi-user diversity. The UARAC is RTS/CTS based, where a receiver measures the SNR of a RTS frame, and then selectively returns the CTS frame with a piggyback information showing the maximum feasible rate. The key feature of the UARAC lies in that the probability that the receiver returns the CTS frame depends on the SNR of the RTS frame and the number of active stations in the network, so that the throughput can be further improved by multi-user diversity besides time-diversity. Furthermore, to optimize the throughput on-line, the UARAC tunes the probability that the receiver returns the CTS frame in heuristic mode. Extensive numerical results and simulation results show that the proposed scheme significantly outperforms the existing adaptive schemes