Efficient and fair pilot allocation for multi-cell massive MIMO systems

In order to reduce the effect of pilot contamination and maximize the system sum rate while guaranteeing the fairness among users, an efficient and fair pilot allocation scheme is proposed for multi-cell massive MIMO systems in this work. The pilot allocation optimization problem is formulated to maximize the sum rate of the system while guaranteeing the fairness among users. A heuristic algorithm, i.e. Min Leakage algorithm, is proposed to solve the optimization problem with rather low complexity. Considering that the Min Leakage algorithm can only provide a suboptimal performance, to further improve the sum rate of the system and the fairness among users, User-Exchange algorithm Based on Greedy pilot allocation (UEBG) is proposed. Simulations are done to validate the effectiveness of the proposed scheme, and results show that the proposed scheme can not only achieve a good sum rate performance, but also guarantee the fairness among users. In addition, it is shown that the proposed UEBG algorithm achieves almost the same performance with the exhaustive algorithm, but with quite low computational complexity compared to the exhaustive algorithm.