A new multi-channel MAC protocol based on Multi-step Channel Reservation

摘要

As the wireless networks become more and more popular currently, how to guarantee the Quality of Service (QoS) for high bandwidth traffic is a prime concern. Compared with most existing Medium Access Control (MAC) protocols using only a single wireless channel as the transmission medium, multi-channel MAC protocols have attracted intensive attention recently because of their capabilities of significantly improving the throughput of wireless networks. One of the most representative multi-channel MAC protocols, called Dynamic Channel Assignment (DCA), tends to specifically assigning one channel as the control channel and the others as data channels. However, dedicating one control channel for all mobile nodes in the network to contending for the opportunities to transmit each data packet results in a large handshake cost on the control channel. In which case, the control channel saturates so rapidly that becomes a bottleneck to lead to poor utilization of the available bandwidth and restrict the network performance. This paper proposes a Multi-step Channel Reservation based Multi-channel MAC (MCR-MMAC) protocol, in which multi-step channel reservation mechanism is used to tackle the above mentioned bottleneck problem. Through scheduled transmissions of packets on data channels, the traffic load on the control channel is decreased dramatically. Hence, significant performance gains can be achieved. Extensive experiments using the ns-2 simulator show that the maximum throughput of MCR-MMAC is nearly up to ten times of that of DCA when seven-step channel reservation is adopted.