Channel-aware Schedulers for {VoIP} and {MPEG4} based on Channel Prediction
Ana Aguiar, Christian Hoene, Jirka Klaue, Holger Karl, Horst Miesmer, Adam Wolisz · 2003
When transmitting multimedia applications over a wireless channel, multimedia traffic is faced with the errorprone, time-varying nature of wireless communication. One means to improve this situation is to adapt the transmission decisions, e.g., time to transmit or parameters like transmission power or FEC to the current, actual state of the wireless channel. Also, semantic-aware adaptation techniques have proven to achieve important quality gains. However, these approaches require modifications to existing applications. In this paper, we investigate how the combination of channel knowledge with different deadlines impacts the perceived quality of voice over IP and MPEG4 encoded video streams. We show that such channel-aware scheduling alone, without requiring any changes to existing applications or protocols, can considerably improve multimedia quality while simultaneously reducing the load on the wireless channel. For voice over IP in particular, we characterise a trade-off between delay and loss rate that optimises the perceived quality. actual state of the wireless channel. Also, semantic-aware adaptation techniques have proven to achieve important quality gains. However, these approaches require modifications to existing applications.