The University of British Columbia

H.263 video bitstreams can be characterized by high peak rates, frequent rate variations, and a high sensitivity to bit errors. Moreover, many interactive/streaming video applications require a tight bound on delay. The paper evaluates the performance of H.263 video transmission on the downlink of a cdma2000 system, and examines some of the tradeoffs needed in the design of such a system in order to meet the above requirements. In order to match the variable source rate to the bandwidth available to mobile cdma2000 video users, real-time smoothing of the video stream is performed prior to transmission. This introduces a delay at the video decoder which varies with the amount of buffering. To reduce the channel bit-error rate (BER), turbo coding is employed, which is also responsible for a delay at the receiver end. Hence, a tradeoff must be achieved between the amount of smoothing and error-correction, in order to respect the total end-to-end delay restrictions. Using entire system simulations, we assess the effects of the parameters of both the smoothing algorithm and the turbo coder on the received picture quality, for a given maximum delay: this work thus presents a joint optimization of real-time smoothing and turbo coding/decoding for H.263 video applications.