Detecting QoS degradation in wireless networks to assist reliable media streaming

This paper describes an approach to detect Quality of Service degradation due to packet congestion within wireless networks. The proposed approach can assist management systems to detect a degradation based on easy determinable packet metrics. Metrics like interface queue length, round trip times and retry ratio are evaluated regarding thresholds and detection performance. With a combination of metrics, a robust detection can be achieved for TCP and UDP streams using a IEEE 802.11 a/b/g ad-hoc network. As soon as a detection event occurs, a channel transition is engaged as an exemplary counter-measure. This successfully solves transmission problems due to congestion.