Patent ID: 8031792

Claim:
A trellis processing apparatus for estimating a transmitted signal from a received signal acquired through a channel, wherein the received signal comprises a sequence of received symbols, the transmitted signal comprises a sequence of transmitted symbols, and the channel is characterized by a channel response estimate comprising a series of channel coefficients, each corresponding to a different time delay, the apparatus comprising: a memory configured to store differences between a received symbol and different products, each of the different products being a product of a channel coefficient corresponding to a least time delay and a different possible transmitted symbol; and a processor configured to calculate a summation of products, each of the products in the summation being a product of a possible transmitted signal symbol and a channel coefficient other than the channel coefficient corresponding to the least time delay, the summation being specific to a branch-start state in a trellis; wherein the processor is configured to combine a result of the summation with different ones of the differences from the memory in a calculation of branch metrics leading to different branch-end states in the trellis.