An Enhanced Reservation-Based Medium Access Control with Scheduling and Admission Control for Voice over Wireless Mesh Networks

Voice over IEEE 802.11 networks is a costeffective solution compared to cellular telephony in small areas and therefore considered among the killer applications of emergent Wireless Mesh Networks (WMNs). However, traditional random medium access control (MAC) protocols used in IEEE 802.11-based WMNs, which are suitable for throughput-sensitive data services, are far from guaranteeing the low delays and the low packet losses required by voice traffic. Therefore, in this paper we propose a new enhanced MAC, called EMDA, combined with a simple scheduling and admission control algorithm, called SAC, that provides a high capacity and quality guarantees for voice over WMNs. EMDA improves significantly the optional Mesh Deterministic Access (MDA) MAC protocol, to provide a much higher voice call capacity thanks to voice packet aggregation and less MDA signaling overhead. EMDA is based on a per-node´s radio interface transmission opportunity reservations that are well dimensioned. Moreover, we further improve the deterministic access of EMDA by proposing a jamming scheme that provides more robustness against interfering non-MDA nodes. The proposed SAC algorithm guarantees hard delay constraints and a uniform voice capacity over WMNs regardless of the number of hops to a gateway (i.e., a mesh router connecting WMN to Internet). Simulation results show that our proposed scheme provides a bigger voice capacity that is uniformly distributed over the WMN and a better performance in guaranteeing hard delay constraints and lower packet losses compared to other schemes.