Joint source-channel coding as an element of a QoS framework for '4G' wireless multimedia
The development of 'Beyond 3G'-B3G-or '4G' networks and applications, with all-IP based ubiquitous and seamless service provisioning across heterogeneous infrastructures, presents a number of challenges beyond existing capabilities conceived so far by the IETF for Mobile IP and by the ITU for Third Generation networks. Management, signaling and transport functions must evolve from different link layer technologies, uniformly and end-to-end, to the packet switched IP-network layer. Global mobility throughout all network types requires capability for seamless handover between different administrative and technology domains, extending at the same time the present edge mobility concept to ad-hoc networks and to mobile networks. Having at least identified, if not solved, these important problems, the technical key challenge for this B3G or '4G' world remains to provide IP-based audio and video communications at the same or at least comparable 'carrier class' and bandwidth efficiency as the corresponding circuit-switched subsystems of 3G and 2G. In the IETF, some elements to achieve this goal have been identified and are under discussion: situated between link and IP layers, the Robust Header Compression (ROHC) framework addresses the problems of spectrum and bandwidth scarcity and of bit errors characterizing wireless links. The fact that, for some applications, erroneous packet payloads can be valuable and better to cope with than lost ones, has inspired the introduction of the UDP-lite transport protocol. Assuming ROHC, UDP-lite and an appropriate inter- or cross-layer signaling mechanism in action, this paper is going to elaborate and incorporate the joint source and channel coding-JSCC-paradigm into a complete QoS framework for 4G mobile wireless multimedia communications. (C) 2004 Elsevier B.V. All rights reserved.
source-channel coding multimedia robust header compression compression wireless communication internet communications source coding