Low Complexity Time-Concatenated Turbo Equalization for Block Transmission without Guard Interval: Part 2 - Application to SC-FDMA

The primary objective of this paper is to apply the CHATUE algorithm, presented in the Part-1 paper of this article, to multi-user Single Carrier Frequency Division Multiple Access (SC-FDMA) Systems. The CHATUE algorithm connects turbo equalizers neighboring in time in the absence of Cyclic Prefix or Guard Interval, where the latest version of the reduced complexity equalization technique, Frequency Domain Soft Cancellation Minimum Mean Square Error turbo equalization is utilized not only to mitigate the inter-carrier interference but also to eliminate the inter-block interferences from the neighboring blocks. Furthermore, doped accumulator is combined with our proposed CHATUE-SC-FDMA system. Extrinsic Information Transfer analysis is used to demonstrate the improvement in convergence property as well as to analyze the bit error rate threshold. This paper provides in detail the time-concatenated turbo equalization algorithm for SC-FDMA, referred to as CHATUE-SC-FDMA, and evaluates its performances. When deriving the algorithm, we also propose, without imposing significant performance degradation, an approximation technique to eliminate the necessity of the covariance matrix inversion.