Method for decoding tail-biting convolutional codes

A method for decoding tail-biting convolutional codes, comprising:

• initializing all beginning states of a trellis diagram;
• calculating forward Viterbi metrics for the states of the trellis diagram;
• tracing back from an ending state of the trellis diagram at a first time instance to a first sate where all surviving paths converge at a second time instance;
• setting the first state to zero and other states at the second time instance to maximum values;
• calculating backward Viterbi metrics for a predetermined period of time from the first state at the second time instance to a second state at a third time instance;
• and
• tracing back from a designated state, which is equal to the second state, at the first time instance to determine a most likely path for the convolutional codes in the trellis diagram.

A method for decoding tail-biting convolutional codes, comprising:

• initializing all beginning states of a trellis diagram;
• calculating forward Viterbi metrics for the states of the trellis diagram;
• tracing back from an ending state of the trellis diagram at a first time instance to a first state where all surviving paths converge at a second time instance;
• setting the first state to zero and other states at the second time instance to maximum values;
• calculating backward Viterbi metrics from the first state at the second time instance to a second state at a third time instance, wherein the second and third time instances have a time interval of a constraint length multiplied by five;
• and
• tracing back from a designated state, which is equivalent to second state, at the first time instance to determine a most likely path for the convolutional codes in the trellis diagram.