| 摘要 |
A time-varying trellis code is used to obtain a desired effective code rate which produces an encoder output directly mappable onto a signal constellation. The time-varying trellis code is obtained by using a variable rate encoder which produces, at its output, the correct number of bits to map directly onto the desired signal constellation. The input data stream is coded at a first code rate during a first selected time interval, and at a second code rate during a second selected time interval. By varying the code rate at periodic intervals, a third effective code rate is obtained.
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