On the Uplink Max-Min SINR of Cell-Free Massive MIMO Systems

Manijeh Bashar, Kanapathippillai Cumanan, Alister Graham Burr, Merouane Debbah, Hien Quoc Ngo

Research output: Contribution to journalArticlepeer-review


A cell-free Massive multiple-input multiple-output (MIMO) system is considered using a max-min approach to maximize the minimum user rate with per-user power constraints. First, an approximated uplink user rate is derived based on channel statistics. Then, the original max-min signalto- interference-plus-noise ratio (SINR) problem is formulated for optimization of receiver filter coefficients at a central processing unit (CPU), and user power allocation. To solve this max-min non-convex problem, we decouple the original problem into two sub-problems, namely, receiver filter coefficient design and power allocation. The receiver filter coefficient design is formulated as a generalized eigenvalue problem whereas geometric programming (GP) is used to solve the user power allocation problem. Based on these two sub-problems, an iterative algorithm is proposed, in which both problems are alternately solved while one of the design variables is fixed. This iterative algorithm obtains a globally optimum solution, whose optimality is proved through establishing an uplink-downlink duality. Moreover, we present a novel sub-optimal scheme which provides a GP formulation to efficiently and globally maximize the minimum uplink user rate. The numerical results demonstrate that the proposed scheme substantially outperforms existing schemes in the literature.
Original languageEnglish
Pages (from-to)2021 - 2036
JournalIEEE Transactions on Wireless Communications
Issue number4
Publication statusPublished - 31 Jan 2019

Bibliographical note

© 2019 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.


  • Cell-free Massive MIMO
  • max-min resource allocation
  • geometric programming
  • uplink-downlink duality
  • convex optimization
  • generalized eigenvalue problem

Cite this