Joint interference alignment and IB-DFE scheme for MC-CDMA systems

Abstract

Interference alignment (IA) is a promising technique that allows high capacity gains in interfering channels. On the other hand, iterative block decision feedback equalization (IB-DFE) based receivers can efficiently exploit the inherent space-frequency diversity of the MIMO MC-CDMA systems. In this paper we combine IA precoding at the transmitter with IB-DFE based processing at the receiver for MC-CDMA systems. The IA precoding is applied at chip level instead of the data symbols level. The receiver is designed in two steps: first an equalizer based on zero forcing (ZF) is used to remove the aligned users' interference, then and after a whitening noise process, an IB-DFE based equalizer is designed to remove the residual inter-carrier interference. Our proposed scheme achieves the maximum degrees of freedom provided by the IA precoding, while allowing a close-to-optimum diversity gain, with performance close to the matched filter bound (MFB).