A new quality of service aware multi-channel multi-interface link layer protocol for wireless mesh networks

Abstract

A new link layer protocol, quality of service hybrid multi channel protocol (QoS---HMCP), that takes into account the need for QoS support in multi-channel multi-interface wireless mesh networks (MCMI---WMNs) is proposed in this paper. QoS---HMCP protocol retains most properties of enhanced distributed channel access (EDCA) mechanism, defined by the 802.11 standard, as well as the basic mechanisms of HMCP protocol. To achieve good network performances with QoS---HMCP protocol in MCMI network, it was necessary to precisely define the channel coordination and procedure for the medium competition of EDCA functions (EDCAFs) after the expiration of interval of time within which a particular EDCAF has the right to initiate data exchange sequences onto the wireless medium--transmission opportunity. Taking into consideration the previously defined conditions, four versions of QoS---HMCP protocol are proposed in this paper. These versions were compared with each other and with basic HMCP with regard to the throughput of user data and delay through the network. The four versions of the QoS---HMCP protocol, multi channel routing (MCR) protocol and chosen metric were implemented in Glomosim simulator. The results have shown that implementation of QoS---HMCP protocol in MCMI---WMN resulted in a very small delay for voice and video traffic, while low-priority traffic categories (best effort and background) were still able to access the media.