On the Impact of Channel Estimation Errors on MAC Protocols for MIMO Ad Hoc Networks

In this paper, we evaluate the performance of a Medium Access Control (MAC) protocol for MIMO ad hoc networks under imperfect channel estimation. To this end, we also present an analysis of channel estimation errors using correlator-based and Minimum Mean-Square Error (MMSE) channel estimators. Unlike similar works, we specifically focus on a scenario where the presence of several simultaneous, symbol-asynchronous signals makes the problem more complicated than in traditional channel estimation. In particular, we show that there is direct dependence of the channel estimation error on the instantaneous channel matrix. The model we propose in this paper makes it possible to quickly evaluate the performance of channel estimation schemes as a function of the system parameters. In this light, we include the effect of channel estimation errors in an ad hoc networking protocol simulator and thoroughly evaluate their impact. Our results show that there exists a significant interplay between the performance of MAC protocols for MIMO networks and the accuracy of channel estimation. Moreover, we show that interesting tradeoffs arise between MAC- and physical level-related parameters.