Due to the packet-fairness property of the 802.11 WLANs, the clients with low rates take longer time to transmit a packet and would reduce the overall network throughput, as well as the per-node throughput of those high data rate clients. We propose a collaborative relay method, which allows high data rate clients to relay traffic for the low data rate clients to improve the network throughput. There are three original contributions made by this paper: 1) we develop a generalized model to analyze multi-hop relay for clients. By using this model, clients that are several hops away from each other may take the advantage of concurrent transmissions. 2) We propose a centralized algorithm to compute multi-hop relay topology for the clients and it can achieve the optimal throughput in our defined model. 3) We propose a distributed multi-hop relay protocol for clients dynamically connected to or disconnected from the network. Simulation results show that our algorithm can improve the throughput up to 42% on average, which is significantly better than the previous work. Up to 75% of the clients in the network use 1-hop or multi-hop relay, instead of connecting to the AP directly, for the performance gain; and up to 39% of the links have the opportunities to transmit concurrently with another link.
['Bo Zhang', 'Zhongming Zheng', 'Xiaohua Jia', 'Kan Yang']
A Distributed Collaborative Relay Protocol for Multi-Hop WLAN Accesses