Index Encoding for GPSM Multiuser MIMO Communication

This work focuses on precoded multiuser MIMO systems with index modulated signal vectors. That means that only certain positions in the signal vectors transmitted to the users contain information symbols (Information Bearing Positions- Ibp)and the particular IBP pattern represents part of the information conveyed to each user. Here we describe systems based on two precoders: Zero Forcing (ZF) and Block Diagonalization (BD) and propose procedures to optimize the choice by the base station of the indexes of the information bearing positions in the transmitted signal vectors (IBP encoding) aiming at improving detection performance. Additional requirements for the considered ZF and BD based systems such as receiver notification and channel estimation are addressed. Numerical results illustrate the resulting bit error rate for both precoders, the influence of the system parameters on the system performance and the performance gain obtained with the proposed IBP encoding optimization procedures,