| 摘要 |
<p>Punctured binary convolutional codes are used in a trellis coded modulation scheme to achieve spectral efficiencies as high as those of multi-dimensional codes, using simple hardware. A base rate 1/2 binary convolutional code is punctured to rate n/k. The output of the punctured encoder 18 is mapped to a four-way partition (60, 62, 64, 66; 120, 122, 124, 126) of a 2<N> point two-dimensional QAM constellation. The four-way partition consists of a two-way partition in both the I and Q dimensions. The two-way partitions of each dimension are used to transmit the two level output of the rate n/k binary convolutional coder. (N-2) "uncoded" bits (24) are transmitted by selecting the unique constellation point in a partition group. The code has an average throughput of (N-2)+2n/k bits per symbol. The invention is also applicable to trellis coded amplitude modulation schemes based on 2<N> possible amplitude levels provided along a one-dimensional constellation. <IMAGE></p> |
