A multimedia transport system for wireless ATM networks architecture and performance

Wireless ATM networks will bring broadband applications like video conferencing to the mobile user. Due to the inherently unreliable nature of the wireless link cell loss is likely to occur, which may result in a violation of the Quality of Service contracts. Within this paper we will present our solution in terms of a generic Quality of Service (QoS) aware Audio/Video Transport Subsystem for wireless ATM. By using an object oriented approach our system can use different, video coding methods for different partners, simultaneously. A QoS controller maps user defined quality parameters down to network and system QoS parameters. Our system works together with network filters and error control modules to help recovering from data loss at the wireless or wired part of the ATM-network. We will evaluate the performance of our sub-system based on simulations for the Magic WAND (Wireless ATM Network Demonstrator) system, which provides wireless access to a fixed ATM network in the 5.2 GHz band. For evaluating the impact of errors at the physical layer, we simulated the transmission of several MPEG-2 transport streams (TS) under different channel conditions resulting in different bit error rates. We analyze the suitability of different packing schemes for encapsulating the MPEG-2 TS pockets into AAL5 frames based on the WAND radio model with respect to error resilience.