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We present an adaptive video transmission scheme for use in a code-division multiple-access network, which incorporates efficient bandwidth allocation among source coding, channel coding, and spreading under a fixed total bandwidth constraint. We derive the statistics of the received signal, as well as a theoretical bound on the packet drop rate at the receiver. Based on these results, a bandwidth allocation algorithm is proposed at the packet level, which incorporates the effects of both the changing channel conditions and the dynamics of the source content. Detailed simulations are done to evaluate the performance of the system, and the sensitivity of the system to estimation error is presented.

A robust scheme is presented for the efficient transmission of packet video over a tandem wireless Internet channel. This channel is assumed to have bit errors (due to noise and fading on the wireless portion of the channel) and packet erasures (due to congestion on the wired portion). First, we propose an algorithm to optimally switch between intracoding and intercoding for a video coder that operates on a packet-switched network with fixed-length packets. Different re-synchronization schemes are considered and compared. This optimal mode selection algorithm is integrated with an efficient channel encoder, a cyclic redundancy check outer coder concatenated with an inner rate-compatible punctured convolutional coder. The system performance is both analyzed and simulated. Last, the framework is extended to operate on a time-varying wireless Internet channel with feedback information from the receiver. Both instantaneous feedback and delayed feedback are evaluated, and an improved method of refined distortion estimation for encoding is presented and simulated for the case of delayed feedback.

Discusses various articles published within the issue, including one on per-path pulse distortion in multiuser detection for Ultra-Wideband communications and another on the design of signaling waveforms for time-hopping impulse radio with limits on the power spectral density.

Discusses the need for a quality-of-service delivery in variable topology networks. Importance of communication in history; Reason for the development of wireless mobile ad hoc networking; Overview of articles dealing with quality-of-service delivery in variable topology networks.

The article introduces a series of articles on telecommunication systems based on code division multiple access (CDMA) technologies. The article include topics on CDMA resource allocation issues, CDMA sequences design, space-time/turbo coded CDMA, chip-interleaving CDMA, and CDMA equalizer.