A Novel Pilot Decontamination Method for Massive MIMO Systems Using Social Spider Optimization Algorithm

摘要

The promising capacity and data rate brought by massive MIMO communication systems lead to consider it as a very prominent fifth generation mobile technology. Pilot contamination is identified as the most significant impairment that limits the exploitation of its optimum capacity. It is caused by the re-use of the same, or at least non-orthogonal pilot sequences, among different cells that degrade the performance of channel estimation. In order to mitigate this issue, we propose a partial re-use of pilot sequences among users in the adjacent cells, which are close to the base station (BS) and also possesses minimum movement velocity. A novel multi factor social spider optimization algorithm (MSSOA), which imitates the cooperative behavior of social spiders, is used for selecting the eligible users for this pilot reuse in the neighboring cells. The algorithm tries to maximize the lowest SINR value for every user in the cell. The performance of the proposed method is evaluated through simulations and it is confirmed that the proposed method gives a better bit error rate (BER), sum-rate, and normalized mean square error (NMSE), over the conventional pilot assignment schemes.