Joint pilot allocation and AP selection for massive access in cell-free massive MIMO

초록

With the exponential growth of connected devices, cell-free massive multiple-input multiple-output (CF-mMIMO) systems have emerged as a promising solution to overcome the limitations of traditional cellular networks. This paper proposes a novel access point (AP) clustering scheme in massive CF-mMIMO. Addressing the critical issue of pilot contamination, this study introduces a max–min distance-based pilot allocation (MMDP) scheme to enhance spectral efficiency (SE) by minimizing the error in channel estimation. Additionally, a novel greedy AP selection scheme is presented that enables centralized decisions to maximize SE and addresses the limitations of the scalable CF-mMIMO scheme. The simulation results confirm the performance gains of the proposed scheme, showing an improvement of up to 14% in the 95%-likely SE compared to the scalable CF-mMIMO scheme. © 2026 Elsevier B.V.

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