A comparative analysis of VoIP support for HT transmission mechanisms in WLAN

The high throughput (HT) 802.11n architecture is mainly aimed at exchanging large chunks of data using bit rates of 216 Mbps in 20 MHz and 432 Mbps (or even higher) in 40 MHz bandwidth respectively. However, for real-time data streams with small payloads like VoIP the performance of 802.11n is not very impressive and performs worse than 802.11a, as we show in this report. In order to overcome this and to accelerate QoS packet transmission to multiple users simultaneously, TGnSync proposed a mechanism for multiuser packet aggregation in the downlink with multiple uplinking responses known as multi response multiple receiver aggregate (MR-MRA). With the closure of the TGnSync group and the emergence of the EWC, an Intel backed 802.lln group, a second mechanism known as power save multiple poll (PSMP) to describe the down link transmission (DLT) and up link transmission (ULT) was introduced [2]. This report presents an analysis on the support for VoIP by an alternative virtual MIMO uplink mechanism that we call simultaneous coordinated channel access (SCCA) and the use of SCCA as a complimentary mechanism in the uplink to the MR-MRA and PSMP schemes to improve the throughput for multiuser transmissions. We show that the combined mechanisms MRA- SCCA and PSMP-SCCA are attractive solutions to meet the demand for QoS capacity over WLANs.