L2Relay: Design and implementation of a layer 2 Wi-Fi packet relay protocol

In this paper, we propose L2Relay, a novel packet relay protocol for Wi-Fi networks that can improve the performance and extend the range of the network. A device running L2Relay is referred to as a relayer, which overhears the packet transmissions and retransmits a packet on behalf of the Access Point (AP) or the node if no ACK is overheard. One important feature of L2Relay is its ubiquitous compatibility, i.e., it is compatible with any Wi-Fi devices, such that one or multiple relayers can be installed in any network easily without any modification to the AP or the nodes. L2Relay is a layer 2 solution that exploits many layer 2 functionalities such as carrier sense. It encompasses unique solutions to link quality measurement, rate adaptation, and relayer selection. We implement L2Relay in the OpenFWWF platform and compare it against the baseline network without a relayer as well as a popular commercial Wi-Fi range extender. Our results show that L2Relay achieves overall better performance than both compared schemes.