Optimized Adaptive Multi Lane technique: For LTE radio access VoIP

Long Term Evolution (LTE) standards have cancelled the circuit switched domain, turning the next generation cellular networks into an all IP system, and VoIP the only way to transport voice. Despite that VoIP codecs are well developed for internet applications, these codecs are not designed to adapt for varying radio channel conditions, as in the case of the classical Adaptive Multi Rate (AMR) codec. With our recently proposed Adaptive Multi Lane (AML) approach, the system is to stream 1, 2 or 4 lanes of speech frames in parallel according to the radio channel conditions. Each lane has a different fractional frame delay increasing the probability of getting out of fading dips. In this paper, the AML technique simulation scenarios were further investigated by experimenting different parameters´ effect, aiming for optimal settings selection. These include codec rates, voice packet durations and inter lane delays, for both male and female utterances. The resulting speech quality Mean Opinion Scores (MOS) were then objectively evaluated. It is shown that by deploying optimal AML parameters´ settings, the resulting LTE VoIP codecs speech quality gain can be efficiently maximized, reaching 50% MOS gains compared to standard single path model.