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Sliding-block coding for input-restricted channels 总被引:1,自引:0,他引:1
Karabed R. Marcus B.H. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1988,34(1):2-26
Work on coding arbitrary sequences into a constrained system of sequences (called a sofic system) is presented. Such systems model the input constraints for input-restricted channels (e.g., run-length limits and spectral constraints for the magnetic recording channel). In this context it is important that the code be noncatastrophic to ensure that the decoder has limited error propagation. A constructive proof is given of the existence of finite-state invertible noncatastrophic codes from arbitrary n -ary sequences to a sofic system S at constant rate p :q provided only that Shannon's condition (p /q )⩽(h /log n ) is satisfied, where h is the entropy of the system S . If strict inequality holds or if equality holds and S satisfies a natural condition called `almost of finite type' (which includes the systems used in practice), a stronger result is obtained, namely, the decoders can be made `state-independent' sliding-block. This generalizes previous results. An example is also given to show that the stronger result does not hold for general sofic systems 相似文献
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