MCCA: Multihop Clear Channel Assessment In 802.11 DCF

Abstract

We present a discussion and study of the RTS/CTS channel clearing mechanism used in the 802.11 DCF and propose a possible improvement. We focus on why the current mechanism is only a single hop process, what disadvantages this presents and what advantages a multihop version of RTS/CTS would bring. We describe why the proposed multihop approach, called Multihop Clear Channel Assessment (MCCA), brings various improvements and how it can be used in isolation in ad hoc or infrastructure mode networks and with or without additional layer 2 (L2) or layer 3 (L3) routing protocols present, depending on the purpose and performance goals of the network. MCCA should not be construed as a L2 ad hoc routing protocol but an enhanced version of RTS/CTS. MCCA is well suited to wireless home networks where it has been shown [1] that even in modest residences, full wireless connectivity is not guaranteed and using additional routing protocols at L2 or L3 may add latency and reduce throughput which could jeopardize the high bandwidth, rich media applications typical of the home network environment. We therefore ask and attempt to answer the question, what can we do to improve 802.11 based wireless networks at the fundamental MAC layer with respect to ensuring as close to full connectivity as possible before resorting to L2 or L3 routing?.