Abstract
The trace-back technique is an effective approach for survivor memory management in the Viterbi algorithm. It is especially attractive when the number of states in the trellis is large, in which case the register exchange approach is impractical due to the area required for wiring. Previous descriptions of the trace-back technique have assumed either one or two trace-back pointers and have made specific assumptions about the speeds of those pointers. In this paper we present a general framework for implementing the trace-back technique with any number of trace-back pointers and with relaxed assumptions about the speeds of the pointers. We also show that the use of additional trace-back pointers reduces the memory requirements. Two implementations of the generalized trace-back techniques based on standard RAMs and custom shift registers are presented.
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A preliminary version of this paper appeared at the 1990 IEEE Global Telecommunications Conference.
The work of C. Bernard Shung was performed while he was at the IBM Almaden Research Center.
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Cypher, R., Shung, C.B. Generalized trace-back techniques for survivor memory management in the Viterbi algorithm. J VLSI Sign Process Syst Sign Image Video Technol 5, 85–94 (1993). https://doi.org/10.1007/BF01880274
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DOI: https://doi.org/10.1007/BF01880274