A novel graph-based approach to low-complexity detection for turbo equalization

We consider the problem of soft-input soft-output detection over channels affected by intersymbol interference. In particular, we introduce a novel (cyclic) factor graph describing the channel and, by applying the sum-product algorithm to it, we derive some detection schemes that can provide impressive complexity reductions with respect to the optimal algorithm. Simulation results are reported which prove that the performance, beside the low-complexity properties, makes the proposed algorithms appealing for turbo equalization in various scenarios of practical interest.