Design and Implementation of an Energy-Efficient Detector for Uplink Cell-Free MIMO Networks

This paper presents the design and hardware implementation of an energy-efficient data detector for uplink cell-free (CF) MIMO networks. The design is based on the DMPACT CF MIMO detection algorithm proposed in [7], which beats other CF detection methods in terms of detection performance and computational complexity. We have proposed several novel techniques in this detector, including eigenvalue decomposition, CORDIC algorithms, and fast inverse square root calculations, to compute the Mahalanobis distances, reducing multiplication complexity by 81%. Additionally, Gaussian approximation was further proposed for complexity optimization. The final hardware design incorporates circuit sharing, outcome reuse, and pipelining to enhance circuit performance. Finally, synthesized using the 28nm CMOS technology, the proposed multi-core hardware operates at 667 MHz and achieves a 10.67 nJ/bit energy efficiency, beating the single-core approach by at least 16%.