Iterative Detection using MMSE-PIC Demapping for MIMO-GFDM Systems

Diverse requirements are foreseen for the 5G cellular system and new waveforms are being researched for the physical layer (PHY), where the non-orthogonal Generalized Frequency Division Multiplexing (GFDM) is one candidate. Its inherent self-interference makes receiver design challenging, particularly when besides inter-carrier interference (ICI) and inter-symbol interference (ISI) also inter-antenna interference (IAI) occurs, as in systems that employ spatial multiplexing (SM) to increase the throughput. To encounter this interference, we apply the prominent minimum mean squared error with parallel interference cancellation (MMSE-PIC) iterative receiver structure to GFDM, and provide a formulation that is suitable for a low-complexity implementation. We analyze the decoding performance employing a well-known current WiMax LDPC code. The proposed demapping algorithm can be implemented with complexity that scales linearly with the number of subcarriers of the system. Analysis of information transfer characteristics shows that the MMSE-PIC demapper for GFDM exhibits potential to outperform the OFDM demapper with a matching code, however, simulations of frame error rate (FER) show inferior performance of GFDM. These results emphasize the importance of a joint waveform and code design in order to exploit the full potential of the MMSE-PIC receiver structure for GFDM.