Patent ID: 7512870
Filing Date: 2009-03-31
Classification: H03M,H04L

Abstract:
1. A method comprising: receiving a message at a communication device, wherein the message comprises a plurality of fields including at least one predetermined field whose bit values are known at the communication device; generating states with reduced uncertainty for the at least one predetermined field in the message, wherein the states with reduced uncertainty are states for a trellis-based decoding process and are associated with the at least one predetermined field of the message such that a maximum likelihood path of the trellis-based decoding process passes through one of the states of reduced uncertainty by the end of the predetermined field when decoding the message, and wherein values for the states of reduced uncertainty are determined by values of bits in the at least one predetermined field; setting a metric for a state of the trellis-based decoding process depending on whether or not the state is one of the states of reduced uncertainty, by: eliminating invalid candidate paths associated with the trellis-based decoding process for states that are not states with reduced uncertainty; and decoding the message for a reduced number of candidate paths based on said eliminating.