A Comparative Study of Bandwidth Requirements of VoIP Codecs over WiMAX Access Networks

WiMAX, as a wireless broadband access technology, aims at providing the end users with broadband services identical to that provided by DSL. The data rate requirements of VoIP connections over WiMAX links greatly depend on the choice and parameterization of the employed codec, the uplink scheduling algorithm, the header overhead of all network layers as well as applied header compression techniques. The knowledge of the exact data rate requirements of key services is very important for network dimensioning and planning. In this paper we provide a study of the bandwidth and delay requirements of VoIP services in WiMAX networks. This includes an analysis of the effects of robust header compression, payload header suppression, voice activity detection with discontinuous transmission and other bandwidth affecting factors. Finally, the overhead and induced delay by each one of the WiMAX uplink scheduling algorithms for real time services is analyzed in this paper.