Improve transmission reliability with multi-AP diversity in wireless networks

Abstract

With the increasing development of IEEE 802.11 based Wireless Local Area Network (WLAN) devices, large-scale WLANs with high dense deployment of user terminals and access points (APs) have emerged widely in various hotspots. Enhancing transmission reliability has been a primary challenge for scaling the WLANs because high dense deployment of user terminals and APs results in too many collisions. In this paper, we investigate the defects of single association mechanism defined in IEEE 802.11 on transmission reliability from network perspective. Then, we propose a multi-AP architecture, with which an AP Controller (AC) is employed to enable each user terminal to associate and cooperate with multiple APs. In this way, the user terminals can benefit from the diversity effect of multi-paths with independent collisions and transmission errors. This paper concentrates on the performance comparison between the proposed multi-AP architecture and that in IEEE 802.11 standard. Extensive simulation results show that the proposed mechanism can obtain much better performance in terms of the throughput per user and the total throughput, and the performance gain is position dependent. Moreover, the unfairness issue in traditional WLANs due to capture effect can be alleviated properly in the multi-AP framework.