QoS-aware adaptive A-MPDU aggregation scheduler for enhanced VoIP capacity over aggregation-enabled WLANs

Currently available aggregation-enabled wireless local area network (WLAN) implementations do not apply aggregate MAC protocol data unit (A-MPDU) aggregation to real-time voice over Internet protocol (VoIP) traffic because of its strict end-to-end delay requirements. When the number of VoIP sessions in WLAN increases, both mobile station (MS) and access point (AP) face heavy voice packet losses leading to unacceptable quality of service (QoS). Therefore, VoIP capacity of aggregation-enabled WLANs like IEEE 802.11n and 802.11ac is very limited under currently available implementations. In this paper, we propose a QoS-aware adaptive A-MPDU aggregation scheduler for enhanced VoIP capacity over aggregation-enabled WLANs, which adaptively applies A-MPDU aggregation to voice traffic at both MS and AP nodes, considering dynamic contention in WLAN, delay in backbone network, and end-to-end QoS requirements of real-time voice traffic. Performance evaluations of the proposed scheme showed that it can achieve as much as 5.3 times bigger capacity compared to the existing implementations, while delivering all voice packets to destination with less than 150ms end-to-end delay and less than 50ms average jitter.1