PRIORI ESTIMATION OF SERVICE QUALITY

IEEE is preparing its new WLAN standard 802.11e in order to be able to cope with the emergent needs of real time traffic over wireless networks. Within this new standard there is an element called the QBSS (QoS enhanced basic service set) load element which should help in solving the problem of candidate access point selection.In this paper we show that QBSS load element can in many cases make incorrect decisions because of the complex interactions between the newly introduced functions EDCA (enhanced distributed channel access) and HCCA (hybrid coordination function controlled channel access). We examine some cases with unexpected correlation between the QBSS load element parameters and the defined QoS (quality of service) metrics. Additionally, we show that the correlation between the number of traffic streams using the same priority and the defined QoS metrics is substantially higher. Therefore we suggest an adjustment in the QBSS load element which enlarges its capabilities in the candidate access point selection.

[1]  Marceau Coupechoux,et al.  Voice over IEEE 802.11b Capacity , 2004 .

[2]  Jinyun Zhang,et al.  A new measurement-based admission control method for IEEE802.11 wireless local area networks , 2003, 14th IEEE Proceedings on Personal, Indoor and Mobile Radio Communications, 2003. PIMRC 2003..

[3]  Q. Ni,et al.  An Efficient Scheduling Scheme for IEEE 802 . 11 e , 2004 .

[4]  G. Boggia,et al.  Feedback Based Bandwidth Allocation with Call Admission Control for Providing Delay Guarantees in IEEE 802 . 11 e Networks ? , 2004 .

[6]  Morris Sloman,et al.  A survey of quality of service in mobile computing environments , 1999, IEEE Communications Surveys & Tutorials.

[7]  Chen Na.  IEEE 802.11 wireless LAN traffic analysis: a cross-layer approach , 2005 .

[8]  J. del Prado Pavon,et al.  Impact of frame size, number of stations and mobility on the throughput performance of IEEE 802.11e , 2004, 2004 IEEE Wireless Communications and Networking Conference (IEEE Cat. No.04TH8733).

[9]  Imrich Chlamtac,et al.  An analytical model for IEEE 802.11e EDCF differential services , 2003, Proceedings. 12th International Conference on Computer Communications and Networks (IEEE Cat. No.03EX712).

[10]  Sunghyun Choi,et al.  Protection and guarantee for voice and video traffic in IEEE 802.11e wireless LANs , 2004, IEEE INFOCOM 2004.