User-Centric Perspective in Random Access Cell-Free Aided by Spatial Separability

In a cell-free massive multiple-input–multiple-output (CF-mMIMO) network, multiple access points (APs) actively cooperate to serve users’ equipment (UEs). We consider how the random (RA) problem can be addressed by such network under occurrence of pilot collisions. To find solution, we embrace user-centric perspective, which basically dictates that only preferred set APs needs UE. Due success strongest-user collision resolution (SUCRe) protocol for cellular (Ce) mMIMO, extend it considering new setting. Besides, establish perspective naturally equips CF with robust fundamentals resolving refer this foundation as spatial separability, enables colliding UEs simultaneously. then propose two novel RA protocols CF-mMIMO: 1) baseline (BCF) resolves collisions concept separability alone and 2) sucre (CF-SUCRe) combines SUCRe principle resolve evaluate our proposed against Ce-SUCRe. Respectively, BCF CF-SUCRe support $7\times $ notation="LaTeX">$4\times more UEs’ on average compared Ce-SUCRe an energy efficiency gain based total power consumed (TPC) per attempt notation="LaTeX">$52\times notation="LaTeX">$340\times . Among procedures, even higher overhead, is superior regarding TPC attempt. This because combination methods allows many disconnected from process without sacrificing much performance. Finally, numerical results reproduced using code package available on: github.com/victorcroisfelt/cf-ra-spatial-separability