A Channel-Hopping Multichannel MAC Protocol for Mobile Ad Hoc Networks

Abstract

Although multiple channels are supported in the physical layer, the IEEE 802.11 MAC-layer mechanism is designed for a single channel. Exploiting multiple channels enhances spatial reuse and reduces transmission collisions and, thus, improves network throughput. Designing a multichannel MAC protocol is much more difficult than designing a single-channel MAC protocol. New challenges, such as the channel allocation problem and the missing receiver problem, must be overcome. Existing multichannel MAC protocols suffer from either higher hardware cost (because of applying multiple transceivers) or lower channel utilization (due to limited transmission opportunity). In this paper, a fully distributed channel-hopping solution, i.e., the cyclic-quorum-based multichannel MAC protocol, is proposed. We use the cyclic quorum in a novel way and the proposed protocol has several attractive features. First, only a single transceiver is needed for each node. Second, any sender is guaranteed to meet its receiver in a short time. Third, each node's channel-hopping sequence is derived from its node ID. This avoids exchanging control messages, such as each node's hopping sequence or available channel list. Fourth, multiple transmission pairs can accomplish handshaking simultaneously. The proposed protocol is simple and efficient. Simulation and real system implementation results verify that our mechanism is a promising multichannel MAC protocol for mobile ad hoc networks.