Multiuser diversity beamforming for downlink channels using modulation division multiplexing
Wireless Communications & Mobile Computing
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The use of multiresolution (MR) joint source-channel coding in the context of digital terrestrial broadcasting of high-definition television (HDTV) is shown to be an efficient alternative to single-resolution techniques, which suffer from a sharp threshold effect in the fringes of the broadcast area. It is shown how matched multiresolution source and channel coding can provide a stepwise graceful degradation and improve the behavior, in terms of coverage and robustness of the transmission scheme, over systems not specifically designed for broadcast situations. The alternative available for multiresolution transmission through embedded modulation and error correction codes are examined. It is also shown how multiresolution trellis-coded modulation (TCM) can be used to increase coverage range. Coding results and simulations of noisy transmission are presented, and tradeoffs are discussed