Multi-Mode Wireless Videophony

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Description/Abstract

A comparative study of arbitrarily programmable, but fixed-rate videophone codecs using quarter common intermediate format (QCIF) video sequences scanned at 10 frames/s is offered. These codecs were designed to allow direct replacement of mobile radio voice codecs in second generation wireless systems, such as the Pan-European GSM, the American IS-54 and IS-95 as well as the Japanese systems, operating at 13, 8, 9.6 and 6.7 kbps, respectively, although better video quality is maintained over higher-rate, 32kbps cordless systems, such as the Japanese PHS and the European DECT and CT2 systems. Best overall performance was achieved by our vector-quantised codecs, followed by the discrete cosine transformed and the quadtree-based schemes, which were characterised by the bit allocation schemes of Table 1. The associated video Peak Signal-to-Noise Ratio (PSNR) was around 30 dB, while the subjective quality can be viewed under http://www-mobile.ecs.soton.ac.uk. A range of multimode wireless transceivers were also proposed, which are characterised by Table 2.