Efficient pilot reuse algorithms for massive MIMO cellular system

Abstract

Summary Pilot contamination has come up as one of the major limitations of massive multiple‐input multiple‐output. In the recent past, the pilot contamination resulted by the pilot reuse in inter‐cell system has been successfully handled. In this paper, three efficient algorithms have been proposed to reduce the pilot contamination in intra‐cell system. These schemes emphasize on assigning the available pilots to the users based upon their channel qualities by considering the interfering degree of the various pilot sequences. The first proposed algorithm is based on water filling approach, which attains the system throughput very close to that of brute‐force exhaustive search algorithm (ESA) and performs the best among the three proposed algorithms in terms of system throughput. The second algorithm is designed for achieving better user fairness (by assigning less interfering pilots to the poor channel conditioned users). The third algorithm improves the system throughput as compared to the second algorithm without losing much in terms of user fairness. Furthermore, the computational complexity incurred by all the proposed algorithms is much less than that of ESA.

Pilot Allocation Technique for Massive MIMO Systems Based on Clustering

“…2 represents the cumulative distribution of the difference of system throughput between proposed and existing algorithms with random pilot allocation for different values of K for the case of C = 2. From the figure, it can be seen that the difference value keeps on increasing upon increasing the user number K. This phenomenon can be easily verified from (6). Also, the proposed algorithm has relatively better output as compared to both the existing algorithms.…”

“…It basically employs a large array of base station(BS) antennas to serve a correspondingly less number of users. For realizing the benefits of massive MIMO, it is necessary for the BS to have the knowledge of channel conditions of the users served by it, known as channel state information (CSI) [5,6]. This is achieved by the transmission of known signals or pilot signals by the users to the BS.…”