A Class of Iterative FDE Techniques for Reduced-CP SC-Based Block Transmission

For conventional CP-assisted (Cyclic Prefix) block transmission systems, the CP length is selected on the basis of the expected maximum delay spread. With regard to SC-based (Single Carrier) block transmission implementations, a full-length CP is recommendable, since it allows good performances through the use of simple FDE (Frequency-Domain Equalization) techniques. Recently, an algorithm for a ”Decision-Directed Correction” (DDC) of the FDE inputs, under reduced-CP conditions, was shown to provide good DDC-FDE performances, without significant error propagation, when using specially designed SC-based frame structures. In this paper, a low-complexity, SDDC-aided (Soft Decision Directed Correction), iterative FDE technique is proposed for reduced-CP, SC-based block transmission systems using conventional frame structures. A more sophisticated, SDDC-aided, Turbo FDE technique is also proposed to provide improved performances in such systems, through a moderately increased complexity. The relations with already known Turbo FDE and related iterative techniques, designed to operate under full-length CP, are established. A set of performance results concerning the proposed SDDC-aided techniques, with several complexity levels, as well as conventional iterative FDE techniques, is reported and discussed. The advantages of the SDDCaided approach are emphasized, including the fact that it can operate in a satisfactory way even when, for the sake of implementation simplicity, no decoding operations are used to improve the iterative FDE process.