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On decoding of multi-level MPSK modulation codesThe decoding problem of multi-level block modulation codes is investigated. The hardware design of soft-decision Viterbi decoder for some short length 8-PSK block modulation codes is presented. An effective way to reduce the hardware complexity of the decoder by reducing the branch metric and path metric, using a non-uniform floating-point to integer mapping scheme, is proposed and discussed. The simulation results of the design are presented. The multi-stage decoding (MSD) of multi-level modulation codes is also investigated. The cases of soft-decision and hard-decision MSD are considered and their performance are evaluated for several codes of different lengths and different minimum squared Euclidean distances. It is shown that the soft-decision MSD reduces the decoding complexity drastically and it is suboptimum. The hard-decision MSD further simplifies the decoding while still maintaining a reasonable coding gain over the uncoded system, if the component codes are chosen properly. Finally, some basic 3-level 8-PSK modulation codes using BCH codes as component codes are constructed and their coding gains are found for hard decision multistage decoding.
Document ID
19900012945
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Lin, Shu (Hawaii Univ. Maui, HI, United States)
Gupta, Alok Kumar (Hawaii Univ. Maui, HI, United States)
Date Acquired
September 6, 2013
Publication Date
May 20, 1990
Subject Category
Computer Programming And Software
Report/Patent Number
NASA-90-003
NASA-CR-186601
NAS 1.26:186601
Accession Number
90N22261
Funding Number(s)
CONTRACT_GRANT: NAG5-931
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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