-C 05 0 E/N(dB) Fig.5.10.6 Capacity of 8-PSK MLC with Gray mapping (in the figure,Ci=C2) 5.10.3多级译码MSD) The component codes Care successively decoded by the corresponding decoder DEC-i At stage i,decoder DEC-i processes not only the block y=())of received signal points,but also decisionsj-of previous decoding stagesj.As long as error-free decisions=are generated by the decoder DEC-j,MSD can be interpreted as an implementation of the chain rule. Decoder for Decoder for C 20 al-2) 士士 Decoder for G cl-1) Figure5.10.7 Note that尽管capacity是相同的for不同labeling strategies,但是对于MLC/MSD with finite code length,labeling strategies(Ungerboeck partitioning.mixed partitioning, Gray labeling)会影响其BER性能。In practice,.we recommend MLC schemes based on Ungerboeck set partitioning,where powerful codes with soft-decision decoding are employed18 -5 0 5 10 15 0 0.5 1 1.5 2 2.5 3 Es /N0 (dB) Capacity(bits/symbol) C0 C1 C2 C Fig. 5.10.6 Capacity of 8-PSK MLC with Gray mapping (in the figure, C1=C2) 5.10.3 多级译码 (MSD) The component codes Ci are successively decoded by the corresponding decoder DEC-i. At stage i, decoder DEC-i processes not only the block ( 0 1 ,., ) N n y y = ∈ − y Y of received signal points, but also decision ( ) ˆ ,0 1 j c ji ≤ < − of previous decoding stages j. As long as error-free decisions () () ˆ j j c c = are generated by the decoder DEC-j, MSD can be interpreted as an implementation of the chain rule. C0 y (1) cˆ (0) cˆ # " ( 1) cˆ A− ( 2) cˆ A− C1 Cl−1 Figure 5.10.7 Note that 尽管 capacity 是相同的 for 不同 labeling strategies, 但是对于 MLC/MSD with finite code length, 不同 labeling strategies（Ungerboeck partitioning, mixed partitioning, Gray labeling）会影响其 BER 性能。In practice, we recommend MLC schemes based on Ungerboeck set partitioning, where powerful codes with soft-decision decoding are employed