A comparative evaluation of VoWLAN call capacity with and without codec´s silence suppression

This paper presents the findings of experiments that were performed on a VoWLAN (Voice over WLAN) cell using the IEEE 802.11b standard. The experiments were simulated using OPNET Modeler 14.0 software. The experiments were aimed at finding the maximum number of simultaneous Voice over Internet Protocol (VoIP) users the VoWLAN cell would support under the G.711 and G.729 codec standards with and without silence suppression. The packetization interval was 10 milliseconds (ms). To determine the capacity of the model under various experiments, we checked three metrics: jitter, delay and packets loss. The findings of the first experiment (without silence suppression) indicated that, the maximum number of simultaneous VoIP users the VoWLAN cell was able to support was 6, using the IEEE 802.11b mode under G.729A codec, which is consistent with recent research findings. The finding of the second experiment (with silence suppression) however, demonstrated that with codec´s silence suppression enabled, the maximum number of VoIP users the VoWLAN cell was able to support was 13, using the IEEE 802.11b mode under G.729A codec.