I. Introduction
Multichannel medium access control (MAC) protocols have attracted considerable attention in recent years because they can increase the capacity of wireless ad hoc networks. Applying multiple frequency channels immensely improves wireless network capacities. Efficient multichannel MAC protocols exploit frequency diversity and utilize network capacity more efficiently than do single-channel MAC protocols. Although the IEEE 802.11b/g and IEEE 802.11a standards [1], [2], respectively, define 3 and 12 nonoverlapping channels that support higher network throughput, the distributed coordination function (DCF) within the commercial MAC protocol of IEEE 802.11 is designed mainly for sharing a single channel between stations. Thus, the IEEE 802.11 DCF cannot function in a multichannel environment. In recent years, a large number of MAC protocols have been developed for exploiting the transmission opportunities in a multichannel environment. This paper proposes a MAC protocol that more efficiently utilizes multichannel resources. Although the 802.11n and 802.11ac protocols increase throughput by using multiple-input–multiple-output technology, which employs multiple antennas at both of the sender and receiver, a large number of stations are still equipped with a single antenna. To exploit the advantages of the single antenna hardware with half-duplex function, several multichannel MAC protocols have been proposed in recent years.