Chained turbo equalization for multiuser SIMO-OFDM systems without cyclic prefix

Chained turbo equalization (CHATUE) is a simple detection scheme for block transmission without cyclic prefix (CP), where turbo equalizers for the several consecutive frames exchange information about the interference components in the form of a posteriori Log-Likelihood Ratio (LLR). Although elimination of CP in the block transmission can significantly increase bandwidth efficiency, the received signal suffers from inter-block interference (IBI), which can not be effectively compensated by block-by-block equalization. In this paper, we apply the CHATUE algorithm to effectively suppress inter-symbol interference (ISI), inter-carrier interference (ICI), and multiple-access interference (MAI) in a Multiuser Single Input Multiple Output Orthogonal Frequency Division Multiplexing (MU-SIMO-OFDM) system without CP. Results of computer simulations show the superiority of our proposed MU-SIMO-OFDM to conventional CP-aided systems, without requiring high computational complexity. The convergence property of the proposed technique is analyzed using the extrinsic information transfer (EXIT) chart. Doped accumulator is used to achieve a mutual information point close enough to the (1,1) point, and also to obtain better matching between the equalizer and decoder EXIT curves.