Trellis coded modulation scheme with low envelope variation for mobile radio by constraining a maximum modulus of a differential phase angle
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United States of America Patent
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Jun 24, 1997
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N/A
app pub date -
Jul 6, 1993
filing date -
Jul 6, 1993
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Abstract
A digital radio communication system employs an encoder for creating a set of encoded bits for each set of input bits. A mapper in the transmitter employs a modulation scheme which is constrained in the maximum phase angle difference between subsequently transmitted symbols. A constellation having a number of redundant symbols within the constrained maximum phase angle is chosen. An iterative search is performed to assign each of these symbols to a set of encoded bits such that the resultant coded scheme provides optimal bit error rate (BER) performance for the channel type. Configuring the encoder and mapper in this manner reduces the transmitted power envelope variation of the transmitted signal, thereby reducing the linearity requirements on a transmitter amplifier. Since transmitted power envelope variation is reduced, battery life of a mobile unit is extended. This manner of configuration also retains significant separation between transmitted sequences, resulting in substantial resistance to interference.
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