Performance evaluation of IEEE 802.11 multi-interface based wireless distribution system (MI-WDS)

Wireless distributed systems (WDS) for IEEE 802.11 WLANs are gaining popularity as an effective mean to extend the network coverage area. However, the use of just one wireless channel restricts their efficiency. In this paper, we propose to use a multi-interface WDS to enhance its performance. We investigate two different scheduling policies the sequencing enforced policy (SEP) and the sequencing relaxed policy (SRP) which depend on whether packet sequencing is enforced within the WDS or rather re-established at its edge. For each policy, we investigated two different, yet very simple scheduling algorithms, the round robin and the random uniform algorithms, to dictate the selection of the interfaces. We show that both policies provide tangible improvements. Conducted simulations show, in particular, that the SRP results in almost doubling the network throughput when using just two interfaces per access point. The SRP policy along with the RR algorithm outperforms the SEP policy though it requires a resequencing action at the edge of the WDS. The end to end delays and the re-sequencing buffer sizes are also evaluated.