CODE: Cooperative Medium Access for Multirate Wireless Ad Hoc Network

Cooperative communications can help combat fading and hence can significantly increase the capacity of wireless networks. Although various schemes have been proposed to leverage this capability, most of the current mechanisms require hardware modification. We present a novel MAC protocol for the multirate ad hoc network, called CODE, to entail simultaneous transmissions of unencoded information by multiple nodes to achieve the power gain of virtual antenna arrays. The key physical layer property that we exploit is an increased transmission rate due to the achieved power gain. Moreover, for bidirectional traffic, we jointly consider using network coding technique at the relay nodes to increase the system throughput. Our design is backward compatible with the IEEE 802.11 standard and only requires firmware upgrade, which is especially suitable for low-end terminals. Our evaluation in both analysis and NS-2 simulations show that CODE is able to improve the system throughput up to 60%.