Convolutional decoder and method of decoding convolutional codes

A convolutional decoder comprising:

• a path metric memory configured to store first path metrics corresponding to states of a first step;
• an Add-Compare-Select (ACS) processor configured to, based on first branch metrics and the first path metrics, select second path metrics corresponding to states of a second step;
• a demultiplexer comprising an input terminal coupled to the ACS processor and output terminals coupled to a first storage and a second storage;
• a multiplexer comprising input terminals coupled to the first storage and the second storage;
• and
• a switch configured to couple an output terminal of the multiplexer to the ACS processor in response to reception of a first selection signal,
• wherein the ACS processor is further configured to:
• read, via the multiplexer, first states respectively corresponding to the states of the first step from the first storage;
• and
• write, via the demultiplexer, the read first states to the second storage in response to the second path metrics being selected.

A method comprising:

• receiving coded bit streams;
• determining a survival path by selecting maximum likelihood path metrics for transitions of states from a start step to a last step based on the coded bit streams;
• and
• selecting whether to perform a trace back for the survival path,
• wherein determining the survival path comprises:
• forming communication paths with a first storage and a second storage;
• and
• reading and writing states of the start step from and to the first storage and the second storage alternately based on the selection of the maximum likelihood path metrics, a state of a first step being transited to a state of a second step corresponding to an address of a storage area to access for the read and the state of the second step corresponding to an address of a storage area to access for the write.