Orthogonal frequency-division multiplex transmission of H.263 encoded video over highly frequency-selective wireless networks

摘要

The video performance of a 155-Mbps wireless asynchronous transfer mode (WATM) proposal and that of a 2-Mbps Universal Mobile Telecommunications System (UMTS) concept is evaluated for a range of low- to high-quality video application scenarios, various propagation conditions, and video bit rates using the H.263 video codec, assisted by a novel packetization and packet acknowledgment scheme. Orthogonal frequency-division multiplexing is invoked over the highly dispersive channels for conveying high-rate video signals. Various binary Bose-Chaudhuri-Hochquenghem and turbo codes are investigated comparatively, with the conclusion that due to the high error resilience of the video packetization and acknowledgment scheme, the increased power of the higher complexity turbo codec does not translate to substantially improved overall system robustness, although the bit error rate and acknowledgment flag error rate are significantly reduced. The whole range of video resolutions and system parameters is summarized in a number of tables. The required channel signal-to-noise ratio for near-unimpaired video quality is about 16 dB for the inherently lower quality, lower resolution video frame formats, but slightly higher, about 18 dB, for the high-definition formats, where the error-induced subjective video degradations become more objectional over the highly dispersive worst case channels used.