A trellis processing technique for estimating a transmitted signal from a received signal acquired through a channel achieves a reduced computational structure when implementing a DDFSE-like branch metrics calculation by pre-storing computed values, which can be re-used. The technique involves storing differences between a received symbol and different products, each of which is a product of a channel coefficient corresponding to a least time delay and a different possible transmitted symbol. A summation of products is calculated, each product 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. The summation is combined with different stored differences in a calculation of branch metrics leading to different branch-end states in the trellis.