Pilot Assignment Based on Weighted-Count for Cell-Free Massive MIMO Systems

Cell-Free massive multiple-input multiple-output (MIMO), which is expected to become one of the core technologies of the B5G and 6G, has attracted more and more researchers' attention. This paper considers a Cell-Free Massive MIMO system with multiple antennas at access points (AP) and a single antenna at users. At the same time, this system applies AP selection technology. To reduce pilot contamination, this paper proposes a new pilot assignment algorithm based on weighted counting, which uses the user's prior geographic information to maximize the pilot reuse weighted distance, and also considers pilot power control in the pilot training phase and AP power control in the downlink phase to verify system performance. Simulation results show that the algorithm can significantly improve system performance.