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Streaming Video? Wirelessly
by Lee J. Nelson
The robustness of today's video compression effectively moderates bandwidth requirements. Thus, while bandwidth remains key, it is not the only issue that affects wireless streaming video. Other factors come into play that are just as critical.
According to Madhukar Budagavi, Jamil Chaoui and Sebastein De-Gregorio of Texas Instruments, Inc. (TI; Dallas, Texas), even if wireless bandwidth suddenly became unlimited, there would still be no assurance that service providers and terminal device manufacturers could impart high-quality streaming video.
Unfortunately, the wireless communications environment?fraught with obstacles including interference, multipath fading, weak signals to crowded air waves and bit-stream errors?is non-conducive to streaming video. The latter involves downloading, decoding and playing back images and sounds with minimal or no buffering. Further, mobile displays are moving targets that dart in and out of coverage zones. To cope with the rigors of streaming video and the vagaries of wireless networks in general, terminal devices must employ a unique blend of specially tailored hardware and software.
The majority of 2G (second-generation) wireless devices are based on dual-chip architecture, featuring a DSP plus a general-purpose processor. In that configuration, pioneered by TI, the DSP handles most communications tasks ( e.g. , modulating/demodulating the bit-stream, video coding, decoding and encryption processing). The second microprocessor is assigned to more general-purpose charges like the user-interface and upper layers of the comms protocol stack.