Wireless access for adaptive video applications

Abstract

This paper presents a wireless access framework for real-time VBR (variable bit rate) transport for next-generation multiservice personal communication networks. We introduce an adaptive VBR service suitable for the mobile networks, where the network provides minimum bandwidth guarantees, and assigns "leftover" bandwidth on a best-effort basis. An adaptive VBR service will help to ease the bandwidth management in the network through guaranteeing only minimum bandwidth. In order to fit this service, we design a layer source coder that separates VBR signal components into a CBR (constant bit rate) portion and a VBR portion. Specific resource allocation procedures are outlined for video traffic coded with a H.283 type two-layer codec and voice traffic generated on a talkspurt-by-talkspurt basis. The protocol is designed with the basic premise that there is a relatively large number of unused voice slots on average that can be used to carry "add-on" video packets. Numerical examples show that prioritized video transport under consideration can significantly improve picture quality, and allow better utilization of wireless resources through statistical multiplexing.