Enhanced quality of service support for triple play services in IEEE 802.11 WLANs

Abstract

Wi-Fi or wireless local area networks (WLANs) are among the most popular wireless internet access technologies used. The major challenge faced by WLANs is the provision of quality of service (QoS) for real-time applications at high congestion periods. IEEE 802.11e draft presents the only comprehensive QoS infrastructure for WLANs which proposes enhanced distributed channel access (EDCA) that propounds the prioritization of medium access for different traffic classes. EDCA while making perceptible improvements for real-time applications neglects non-real-time applications by allocating their share of the bandwidth to the former in an inefficient manner. In our study, we have found that there are considerable design improvements possible for IEEE 802.11e-based QoS propositions. This paper proposes a novel medium access and transmission mechanism for IEEE 802.11 WLANs that is specifically designed to ensure QoS for triple play services. Based on our study regarding the traffic characteristics of triple play services, we propose a mechanism that adaptively uses the medium access and transmission parameters according to the traffic characteristics of the applications, for better utilization of the available bandwidth. The mechanism also proffers higher medium access priority to the access point as compared to the stations in order to cope with the issue of uplink/downlink traffic asymmetry. Simulation-based analysis of the proposed mechanism compares its performance with EDCA. The proposed mechanism offers promising results in terms of packet loss, packet delay and throughput, and thus ensures QoS for voice, video and data transfer applications.

QoE Modeling for Voice over IP: Simplified E-model Enhancement Utilizing the Subjective MOS Prediction Model: A Case of G.729 and Thai Users

“…Excluding the original version of this work [2], the most similar works to this research are [14] and [59] which are the previous work before this research article which only focused on the G.711 codec and Skype which uses the SILK codec respectively. Therefore, this work fulfills the gap which has not been studied which is one of the most important ITU-T codec used in VoIP traffic, 93 % [18].…”

“…As referred in [18] more than 90 % of VoIP traffics, which uses ITU-T codecs, use the G.729 codec while the rest of the VoIP traffic uses G.711. For the G.729, it was issued by ITU-T [19].…”

“…Daengsi & Wuttidittachotti (2013) [43] The Thai bias factor and MOSCQE-TH was proposed for G.711 as shown in (18) and (19), where Thai bias factor is the factor obtained from subjective tests with a groups of native Thais, MOSCQE stands for MOS from an E-model tool, K is 5 for Thai, D stands for delay (s); 0s<delay<0.8s only, L stands for loss rate; 0 %<loss<10 % only, MOSCQE-TH stands for objective-MOS from E-model with Thai bias factor (BiasTH). BiasTH = -K(56.12-255.4L+88.48D-901DL-179.88D 2 )/10 The improved the simplified E-model was proposed for several codecs (e.g.…”

Maximizing the stable throughput of high-priority traffic for wireless cyber-physical systems

“…802.11 DCF (that provides a uniform channel contention access) is a special case of 802.11 EDCA (that provides a prioritized channel contention access). Compared with DCF, EDCA can support quality of service for real-time applications and therefore has received continuing attention [23,24]. In EDCA, nodes belonging to high-priority (HP) access categories (ACs) are configured with a maximum contention window (CW) as small as 16, while nodes belonging to low-priority (LP) ACs are configured with a maximum CW as large as 1024.…”