B. SIMSEK and K. WOLTER and H. COSKUN: ANALYSIS OF THE QBSS LOAD ELEMENT ANALYSIS OF THE QBSS LOAD ELEMENT OF IEEE 802.11E FOR A 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.