Uplink Pilot Design for Multi-Cell Massive MIMO Networks

In massive multiple-input multiple-output (MIMO) systems, the effect of inter-user interference and noise can be suppressed through simple signal processing techniques. However, pilot contamination, which results from the use of a correlated pilot, causes performance bottleneck for massive MIMO networks. In this letter, a pilot design algorithm based on alternating minimization is developed to alleviate the pilot contamination in multi-cell massive MIMO systems. Contrary to the existing pilot reuse protocols that restrict the pilot length to be an integer multiple of the number of users, the proposed method designs a pilot with an arbitrary length. Hence, pilot sequence can be designed more flexibly to maximize spectral efficiency.