Distributed medium access control (MAC) protocols are essential due to the flexible and self-organizing nature of ad hoc networks. Scheduling protocols have been popular choices, because they guarantee access to the channel for each transceiver. The disadvantage with these scheduled approaches is that they are inefficient when the network has low traffic loads. Consider a time-division multiple access (TDMA) schedule where nodes are assigned time slots in which they are allowed to transmit. If a particular node is scheduled but has no traffic to forward, then the time slot is wasted. Because the channel has been reserved for use by that particular node, other nodes in the network with traffic to forward are unable to do so. We investigate strategies to improve the performance of TDMA scheduling protocols for ad hoc networks using radios with multiple antennas. Multiple antennas at each radio enables the use of a physical layer technique known as multiple-input multiple-output (MIMO) that leverages the spatial dimension. The antennas allow for both spatial multiplexing and interference cancellation. Spatial multiplexing allows for multiple parallel data streams to be transmitted at the same time. Interference cancellation is used to selectively pick neighbors that do not receive interference from a transmission. Our protocol uses both techniques to allow unscheduled nodes to transmit if the slot is not fully utilized. Using a custom simulation, we show that Lyui\u27s scheduling protocol can be extended to support MIMO and time slot sharing. Our new protocol provides performance improvements with regards to end-to-end completion, throughput, and average delay
