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US 5,996,112 AGranted
Area-efficient surviving paths unit for Viterbi decoders
AssigneeLSI Logic Corporation
InventorsDariush Dabiri, Daniel A. Luthi, Advait M. Mogre
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Abstract
This invention concerns a novel Viterbi decoding apparatus and method in which a survivor path unit (SPU) implements the traceback method with a RAM which stores path information in a manner which allows fast read access without requiring physical partitioning of the RAM. This results in an implementation that requires less chip area than conventional solutions.
Claims17
An apparatus for Viterbi decoding of an encoded signal comprising:
- an execution unit adapted to receive said encoded signal represented as a sequence of code words indicative of transitions between successive encoder states, wherein the execution unit attributes said transitions to a plurality of respective survivor path extensions;
- an interface unit coupled to said execution unit for receiving said survivor path extensions and forming a first path segment from a defined number of said survivor path extensions;
- a memory unit coupled to said interface unit for storing said first path segment;
- and
- a traceback register having a number of register slots greater than the defined number of said survivor path extensions, wherein the traceback register is coupled to said memory unit to receive a sequence of path segments comprising the first path segment and a second path segment which arrives upon the traceback register subsequent to the first path segment, and wherein the second path segment displaces a portion of said first path segment within the traceback register, and wherein the portion is forwarded to said memory unit for partially addressing a third path segment whose address is completed upon dispatch of said second path segment.
2 more elements
A digital communications system comprising:
- an encoder configured to receive a digital signal and thereafter provide an encoded digital signal;
- a discrete-time channel coupled to receive and transport said encoded digital signal;
- a Viterbi decoder comprising:
- an execution unit configured to receive said encoded signal and thereafter determine a survivor weight and a survivor path extension for each of a plurality of possible encoder states;
- a memory unit coupled to receive a path segment consisting of a defined number of survivor path extensions for each of said plurality of possible encoder states;
- and
- a traceback register of a length greater than said defined number of survivor path extensions in a path segment, coupled to said memory unit to receive a sequence of path segments comprising a current path segment and a subsequent path segment by iteratively displacing a portion of the contents of said traceback register by said defined number for each path segment of said sequence, wherein said portion is used to read a group of potential subsequent path segments from said memory unit and the current path segment is thereafter used to determine said subsequent path segment from said group.
4 more elements
A method for Viterbi decoding of an encoded signal comprising the steps of:
- receiving said encoded signal and thereafter determining a survivor weight and a survivor path extension for each of a plurality of possible encoder states;
- storing in a memory unit a path segment consisting of a defined number of survivor path extensions for each of said plurality of possible encoder states;
- and
- using a traceback register of a length greater than said defined number of survivor path extensions in a path segment to receive a sequence of path segments comprising a current path segment and a subsequent path segment by iteratively displacing a portion of the contents of said traceback register by said defined number for each path segment of said sequence, determining from said portion a memory unit location of a group of potential subsequent path segments, and thereafter determining from the current path segment said subsequent path segment from said group.
1 more element
Dependencies are inferred from the claim text.