NS3 simulation and analysis of MCCA: Multihop Clear Channel Assessment in 802.11 DCF

We present a new method for routing MAC frames at layer 2 (L2) within an 802.11 MANET. The new method, Multihop Clear Channel Assessment (MCCA), improves on the RTS/CTS mechanism used in the 802.11 DCF by extending it from a single hop protocol to a multihop one. Such an approach can, in some circumstances, eliminate the need for a routing protocol at layer 3 (L3), since frames, instead of being routed at L3, are forwarded from node to node across multiple hops at L2. This can yield considerable performance improvements due to the absence of additional routing traffic and processing at L3, especially under highly mobile scenarios. We review the results obtained by implementing MCCA using the NS3 network simulator with suitably modified 802.11 source code. We analyze static and mobile ad hoc network scenarios using MCCA when compared to a L3 routing protocol such as Optimized Link State Routing (OLSR) and Ad hoc On demand Distance Vector (AODV). Using NS3, we ultimately demonstrate that in certain scenarios, MCCA at L2, vs a L3 routing protocol, indicates significant improvements in key MANET performance metrics such as Quality of Service (QoS), average latency, packet delivery ratio and device power consumption.