LA-MAC: A Load Adaptive MAC Protocol for MANETs

The performance of prevalent MAC protocols in MANETs relies on the level of contention in networks. While contention-based MAC protocols such as CSMA suffer from inefficiency under high contention, slot-based MAC protocols such as TDMA perform in the opposite way. In this paper, we propose a hybrid protocol to which we refer as Load-Adaptive MAC (LA-MAC) protocol for MANETs. By adaptively switching its running mode between CSMA and TDMA, LA-MAC achieves high channel utilization under both high and low contention. We report our implementation of LA-MAC on a MANET testbed formed by a collection of Multiple-Input Multiple-Output (MIMO) Universal Software Radio Peripheral (USRP) software defined radio nodes. We program the PHY layer of USRP nodes using GNU Radio and integrate LA-MAC with the PHY layer implementation of USRP. Through experimental studies, we demonstrate the performance improvements of LA-MAC relative to CSMA and TDMA.