Adaptively switching between CSMA and SD-CSMA in multi-antenna based Ad Hoc Networks

Carrier sense multiple access (CSMA) is the conventional medium access method used in wireless ad hoc networks. it can be enhanced as a space-division based CSMA (namely, SD-CSMA) by using multi-antenna techniques, which allows concurrent link communications in the network. In this paper, we present a MAC design that can adaptively switch between CSMA and SD-CSMA in multi-antenna based ad hoc networks. We first investigate the CSMA mode and the SD-CSMA mode by considering several practical constraints from MIMO physical layer, which include imperfect channel estimation, modulation and coding scheme, MMSE detection, power constraint and packet length. We then propose a selection criterion that adaptively switches between CSMA and SD-CSMA based on current wireless channels among nodes. Simulation results verify that the proposed design can outperform both the CSMA mode and the SD-CSMA mode in terms of aggregate throughput.