A pilot contamination elimination (PCE) precoding was recently proposed for multi-cell massive MIMO systems with distributed antenna subarrays, where the number of subarrays is required to be not less than the number of users. In this paper, we consider practical scenario of insufficient number of subarrays, and propose a corresponding PCE precoding scheme. The key idea of the proposed scheme is to utilize multiple pilots in one cell rather than single pilot in the original scheme. It is shown that by separating users into multiple groups according to the associated pilots, multiple downsized equivalent MIMO channels can be obtained, which linearly reduces the required number of subarrays and therefore enable the PCE precoding. This linear relation based interpretation also introduces a new optimization problem of finding subarray power normalization factors to maximize signal-to-noise-plus-interference ratio, where an optimized solution is proposed. Finally, simulation results confirm the validity of the proposed PCE precoding scheme.
On the Precoding for Multi-Cell Massive MIMO Systems with Distributed Antenna Subarrays
2016-09-01
189757 byte
Conference paper
Electronic Resource
English