Enhancing data rate efficiency in multi-cell massive MIMO systems through pilot resource allocation

Pilot contamination (PC) limits the system's performance and highly reduces the data rates. To overcome this problem and improve the data rate of a multi-cell massive MIMO system, a modified soft pilot reuse (mSPR) is proposed. For clustered users, mSPR assigns the same pilot set to low PC severity centre zone users, reusing them in a grouped cell. Centre zone users are randomly assigned pilots from the same group, with the maximum user serving as the pilot reference for orthogonal allocation. The simulation result shows the data rate improvement of the multi-cell multi-user massive MIMO system with the proposed mSPR pilot resource allocation. The number of orthogonal pilots is reduced, improving the achievable uplink rate and spectral efficiency over pre-existing schemes. With different numbers of base station antennas and transmission power, the proposed mSPR pilot resource allocation scheme provides average data rates of 3.5 bps/Hz and 2.78 bps/Hz, respectively.