User–Level QoS Assessment of Audio–Video IP Transmission over Link Quality–Based Ad Hoc Networks

This paper assesses user–level QoS (perceptual QoS) of audio–video streaming over wireless ad hoc networks. We employ the method of successive categories, which is a psychometric method, for the user–level QoS assessment. In order to achieve high user–level QoS, we employ link quality–based routing, which takes account of link quality such as signal strength and link utilization level for route selection. We adopt three link quality– based routing protocols: OLSR–SS (Signal Strength), AODV– SS, and LQHR (Link Quality–Based Hybrid Routing). OLSR–SS is a proactive routing protocol, while AODV–SS is a reactive one. LQHR is a hybrid protocol, which is a combination of proactive and reactive routing protocols. We also employ media synchronization control in the application layer. We performed computer simulation with ns–2 by assuming an IEEE 802.11b mesh topology network with 24 nodes. We then assessed user– level QoS by a subjective experiment with 30 assessors. From the assessment results, we found that AODV–SS achieves the best user–level QoS and that LQHR is effective in networks with short inter–node distances.