Antenna Design For Noncoherent Massive MIMO Systems

Massive MIMO is one of the key technologies that enables an increase in capacity in multi-user MIMO systems. However, these systems suffer from high channel estimation complexity and its degradation due to pilot contamination. An attractive way to overcome the key problems of massive MIMO is to resort to noncoherent detection since no actual channel knowledge is needed at the receiver. In this paper, an appropriate antenna design at the base station is proposed when applying noncoherent detection methods. Thereby, the influence of the main antenna characteristics, namely the radiation pattern, gain, and mutual coupling on the symbol error rate performance is assessed for realistic antennas. The evaluation is based on the COST 2100 channel model, properly adapted to the massive MIMO setting. It is shown that proper antenna design can enhance the symbol error rate performance in the noncoherent case in contrast to coherent detection. More specifically, the base station should be equipped with high gain and highly directional antennas. In addition, mutual coupling between adjacent antenna elements at base station may enhance the system performance when present.