On the Use of Multiple Antennas to Reduce MAC Layer Coordination in Ad Hoc Networks

This paper investigates an important tradeoff in wireless ad hoc networks concerning the allocation of resources to the PHY and MAC layers. We compare two approaches: One which employs a non-coordinated slotted ALOHA MAC with multi-antenna PHY, and one which employs a tightly coordinated MAC and single-antenna PHY. For both cases, we derive new closed-form throughput expressions. Based on these, we show that using simple slotted ALOHA in conjunction with multiple antennas can provide a higher throughput than fully coordinated access protocols in various practical scenarios. Our results are confirmed through comparison with Monte Carlo simulations.