A local estimation of node quantity and channel density for VoIP applications over IEEE 802.11e WLANs

IEEE 802.11 WLANs have reached an important stage and have become a common technology for wireless access due to its low cost, ease of deployment and mobility support. However, IEEE 802.11 standard cannot support desired Quality of Service (QoS) for delay-sensitive multimedia applications. Therefore, IEEE 802.11e standard which aims to support QoS by providing different priorities to different types of frames was specified in 2005. However, there are still unsolved performance issues such as optimization of throughput, limiting the delay and packet loss ratio. In this paper, we first present a local estimation method of node quantity and channel density to let the mobile nodes change their parameters according to the channel conditions. Then, we propose a QoS adaptation for delay-sensitive VoIP applications. Proposed algorithm only uses its local information and can be easily implemented without any changes on the current IEEE 802.11e standard. Simulation results show better voice quality and higher overall throughput than the standard IEEE 802.11e.