We consider the turbo frequency domain equalization (FDE) approach based on expectation propagation (EP) to the single-carrier with index modulation (SCIM) transmission over frequency-selective channels. The SCIM-FDE system implements vector-by-vector signal transmission in the time domain, in which elements within each transmitted symbol vector display correlation. In this paper, we propose a novel vector-wise EP (VW-EP) equalization, where the discrete prior distribution of each symbol vector is approximated with a multivariate complex Gaussian distribution. Hence the extrinsic information in the EP feedback is extended to be in terms of the mean vector and covariance matrix. The effectiveness of the proposed scheme can be validated through the error-correction performance and extrinsic information transfer (EXIT) analysis. Numerical results show that the SCIM-FDE transmission with the VW-EP turbo equalization demonstrates remarkable performance.

An iterative intercell interference cancellation algorithm is introduced to improve the receiver performance of uplink transmission in multicell networks. At first, the uplink signal detection is performed independently in each cell according to minimum mean squared error (MMSE) criterion. Subsequently, the detection results are applied to reconstruct the transmit signals of different users and cancel their interference to neighboring cells. With the help of reconstruction results, the MMSE detection matrix of each cell is updated. The channel responses of both efficient and interference links are estimated with the help of pilots. The pilot allocation parameter is introduced to indicate the quality of channel estimation. The simulation results indicate that intercell interference can be greatly mitigated by the proposed algorithm with a moderate number of receiver antennas at the base station.