Efficient mapping of multiple VoIP vocoders in WiMAX systems

This paper addresses the problem of efficient mapping and allocation of voice over IP (VoIP) traffic with multiple VoIP vocoders in WiMAX systems. We show that by taking advantage of the periodicity of VoIP frames, generated by multiple vocoder types, and by applying semi-fixed allocations in the existing resource allocation process, the mapping overhead can be reduced substantially. We present a system model that allows the evaluation of the proposed solutions for the problem at hand. Using this model, we show that the problem is NP hard and present a set of observations on the resource allocation process leading to good mapping decisions from the perspective of mapping overhead. We present a new mapping algorithm that implement the decisions and show by extensive simulations that the proposed mapping algorithm can reduce the overhead down to 25% of the overhead experienced in orthogonal frequency division multiple access (OFDMA)-based systems such as WiMAX and IEEE802.16, while retaining a low computational complexity.