Faculty of Science and Technology

Wireless Video Transmission:

from joint source and channel coding to cross-layer design

Dr. Maria Martini

Senior Lecturer in wireless and mobile communications

Faculty of Computing, Information Systems and Mathematics

Kingston University

Penrhyn Road, Kingston-Upon-Thames

London, KT1 2EE, UK

Phone: +44 (0) 20 8547 7900

Fax: +44 (0) 20 8547 7972

e-mail: mgmartini@ieee.org

m.martini@kingston.ac.uk

Abstract:

Recently, joint source and channel coding and decoding (JSCC/D) techniques that include a co-ordination between source and channel encoders were investigated, in particular for transmission of audio data, images and video over wireless channels. It was shown that, for wireless audio and video transmission, separate design of source and channel coding is usually not optimal, nor it is always applicable, in particular when transmitting data with real-time constraints or operating on sources whose encoded data bit error sensitivity varies significantly. With joint source and channel coding, the transmission system can be adapted to source characteristics, either at channel coding level or through source adaptive modulation. JSCC/D techniques may require the use of rate/distortion curves or models of the source in order to perform the optimal compromise between source compression and channel protection. Similarly, source compression and resilience can be adapted to channel and network characteristics. Joint source and channel coding involves joint design of the source encoder, at the application layer, and of channel encoder/modulator, at the physical layer. In order to realistically perform JSCC/D, it is thus necessary to allow the flow of information to be exchanged in the transmission system and a cross-layer approach is needed. Cross layer design is a recent further evolution of the concept of joint source and channel coding, targeting at jointly designing the classically separated OSI layers. Characteristics and limits of such approach will be described, together with approaches proposed by the speaker and under study in the WMN group in Kingston University.