Mitigating Control Channel Saturation in the Dynamic Channel Assignment Protocol

Abstract

Multi-channel MAC protocols that rely on a dedicated control channel (CC) for data channel reservation face the problem of control channel saturation. When the control channel becomes the bottleneck, data channels are not fully utilized and the spectrum allocated for the network is not used efficiently. For a popular dedicated control channel based multi-channel MAC protocol, the dynamic channel assignment protocol (DCA), we propose and compare two methods for mitigating control channel saturation. The first method is based on the ability of modern wireless cards to use different channel bandwidths. Increasing the bandwidth of the CC allows higher transmission rates and thereby relieves the saturation on the CC. The second method involves TXOP (Transmission Opportunity)-like burst-transmissions, where several date packets are transmitted using one reservation operation on the control channel. Network simulations and analysis show that, in an 802.11 based network, the bandwidth adaptation method yields a throughput improvement of around 30%. The TXOP mechanism performs much better and increases the throughput by a factor of 2 to 10, depending on the length of the data packets.