1. Traverse through trellis

2. Compute hamming distance between the branches of received word and those in the trellis

– at each level, consider two paths entering the same node

– from those two paths, the one that is closer to received word is retained, and the other path is discarded

– proceeding this way, at each stage one path will be saved for each node. These paths are called the survivors.

3. Each survivor is associated with a metric of the accumulated hamming distance.

– metric represents the discrepancy between received signal Y and decoded signal at particular node.

– can be added while traversing the trellis to get accumulated metric.

4. carry out this process until the received sequence is considered completely

5. choose survivor with the smallest metric.

– if two paths have same metric, choose one of them at random.