A Practical Cross-layer QoS Mechanism for Voice over IP in IEEE 802.11e WLANs

Abstract

In this paper, we study the behavior of Voice over IP (VoIP) traffic over IEEE 802.11 wireless networks. Specifically, we propose a QoS provisioning mechanism for VoIP traffic, and suggest a practical solution to configuring the 802.11 e Enhanced Distributed Control Access (EDCA) parameter sets for different types of traffic. With our mechanism, the EDCA parameter sets can be easily configured via software interface in off-theshelf WiFi phone products and it is not required to modify the operations of Access Points or 802.11 M\AC layer protocols. The performance of our mechanism is evaluated via ns-2 simulations and via laboratory experiments over Quanta's 02 dual-mode handsets. The results show our mechanism can provide effective and efficient QoS provisioning for VoIP traffic over IEEE 802.11 WLANs.

Tuning IEEE 802.11e for wireless mesh networks

“…Other works [12,13,14] expect to provide service guarantee to critical ACs, like voice and video. The majority of them are based on the adequate allocation of AIFS.…”

“…Considering this analysis, the values proposed in this work for the access parameters are based in [12], except that the contention windows of all access categories follow the values suggested in the standard, when the physical layer is IEEE 802.11g. They are presented in Table II (a).…”

“…The majority of them are based on the adequate allocation of AIFS. The work in [12] proposes a static configuration of the access parameters to provide service guarantee to voice over IP (VoIP) traffic without intervention in the standard MAC mechanisms and not degrading significantly the other traffic classes or reducing drastically the aggregated network throughput. It considers that AP traffic needs a more aggressive parameter set because it aggregates the other stations traffic.…”

“…So, to provide service guarantee to class i, the AIFSN of the immediately less important class j has to be greater than or equal to the sum of the AIFSN and the CWmax of class i, as stated in (2) [12].…”

“…Many works in the literature [9,10,11,12,13,14,15] aim at adapting the access parameters defined by the 802.11e standard to some specific network scenario, to achieve an efficient channel resource usage or a fair resource sharing among traffic classes and to provide service guarantees to critical applications.…”