Reservation-Based Directional Medium Access Control (RDMAC) Protocol for Multi-Hop Wireless Networks with Directional Antennas

In this paper, we study the issues of medium access control (MAC) mechanisms for multi-hop wireless networks with directional antennas. Specifically, we explore the location-dependent carrier sensing problem and the interference problem caused by the minor lobes of antennas. Existing solutions to directional antenna MAC problems rarely account for the impact of minor lobes and typically assume that the neighboring nodes' locations are known a priori. As a result, they are not applicable to practical systems or to mobile nodes. In this paper, we propose a Reservation-based Directional MAC (RDMAC) protocol for multi-hop wireless networks with directional antenna. This mechanism operates in sessions. Each session comprises two periods, namely, a reservation period and a transmission period. The reservation period is further composed of a set of two phases, namely, a probing phase and a beam-indication phase. The mechanism is designed to reduce the interference among neighboring nodes and to increase the network throughput. The performance of the proposed mechanism is evaluated analytically and via the ns2 simulator. The results show that our mechanism outperforms existing solutions in terms of higher throughput and lower delay.