Throughput and Fairness Improvement for WLANs with Long Propagation Delay Coexisting with Conventional WLANs

Long propagation delay in wireless local area networks (WLANs) such as long distance WLANs and WLANs with radio-over-fiber (RoF) technology increases frame collisions. In particular, when a conventional WLAN coexists with the WLAN with long delay, the propagation delay causes serious throughput degradation and unfairness between the uplink and the downlink in the WLAN with long delay. In this paper, we focus on WLANs with RoF technology (RoF WLANs), and to resolve these problems, we propose a method for improving system throughput and fairness between uplink and downlink transmissions. A numerical analysis based on the proposed model and a simulation evaluation show that the proposed method increases the total system throughput by 25% while achieving MAC-layer fairness between the uplink and downlink throughput for RoF WLANs, and increases the TCP throughput in RoF WLANs to the same level as conventional WLANs. Moreover, our proposed theoretical model for the coexistence of RoF and conventional WLANs agrees with the simulation results.