Channel-adaptive wideband wireless video telephony

The fundamental advantage of burst-by-burst (BbB) adaptive intelligent multimode multimedia transceivers (IMMTs) is that-irrespective of the propagation environment encountered-when the mobile roams across different environments subject to path loss; shadow- and fast-fading; co-channel-, intersymbol-, and multiuser interference, while experiencing power control errors, the system will always be able to configure itself in the highest possible throughput mode, while maintaining the required transmission integrity. Finding a specific solution to a distributive or interactive video communications problem has to be based on a compromise in terms of the inherently contradictory constraints of video quality, bit rate, delay, robustness against channel errors, and the associated implementational complexity. Considering some of these tradeoffs and proposing a range of attractive solutions to various video communications problems is the basic aim of this overview. The article portrays a range of proprietary video codecs and compares them to some of the existing standard video codecs. A number of multimode video transceivers are also characterized. Systems employing the standard H.263 video codec in the context of wideband BbB adaptive video transceivers are examined, and the concept of BbB-adaptive video transceivers is then extended to CDMA-based systems