Application level QoS control in wireless LANs

Application level QoS control can be used to provide more complete end-to-end QoS. This is particularly important when the network is not able to support QoS. One of the representative application level QoS mechanisms is adaptive encoding, i.e., codec-based QoS control, which adjusts encoding parameters, e.g., codec bit rate, according to the wireless channel status. This paper proposes an adaptive codec-based QoS control mechanism for wireless LANs, which dynamically adjusts the length of the voice packet payload (and thereby controls the codec bit rate) by using the QoS feedback from the wireless network. The proposed mechanism is able to enhance end-to-end QoS performance and provide desirable voice quality even when there is traffic congestion in the wireless LAN. This paper also shows the effectiveness of the mechanism by presenting simulation results in terms of throughput, packet loss, delay, and jitter.