The design trade-offs of interactive wireless video systems are discussed and performance comparisons are provided both in the context of second-and third-generation wireless videophone systems. We commence our discussions by a comparative study of arbitrarily programmable, but fixed-rate videophone codecs using quarter common intermediate format (QCIF) video sequences scanned at 10 frames/s. These proprietary codecs were designed to allow direct replacement of mobile radio voice codecs in

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... d 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. From the range of codecs investigated, 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 bitallocation schemes of Table 2 . The associated video Peak Signal-to-Noise Ratio (PSNR) was around 30 dB, while the subjective video quality can be assessed under http://www-mobile.ecs.soton.ac.uk. A range of multimode wireless transceivers were also proposed, which are characterised by Table 3 . The second part of the paper is dedicated to burstby-burst (BbB) adaptive wireless video transceivers employing the standard H.263 codec. It is demonstrated that the proposed BbB adaptive transceivers provide an improved video performance in comparison to their statically reconfigured counterparts in