Fairness in a Class Barring Power Control Random Access Protocol for Crowded XL-MIMO Systems

• Published in: IEEE systems journal Vol. 16; no. 3; pp. 4574 - 4582
• Main Authors: Nishimura, Otavio Seidi, Filho, Jose Carlos Marinello, Abrao, Taufik, Souza, Richard Demo
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 3GPP; Access class barring with power control (ACBPC); Access control; Antenna arrays; Collisions; Connectivity; Delays; extra-large MIMO (XL-MIMO); fairness; grant-based protocols; Massive MIMO; massive multiple-input–multiple-output (MIMO); nonstationarity; Power control; Protocols; Random access; random access (RA) protocol; Receiving antennas; Spatial resolution; Visibility; visibility region (VR)
• ISSN: 1932-8184; 1937-9234
• DOI: 10.1109/JSYST.2022.3156696

This article focuses on conceiving a random access (RA) protocol able to provide connections for a vast number of devices subject to intensive collisions in an extralarge massive multiple-input-multiple-output (XL-MIMO) system equipped with a uniform rectangular array (URA). The recently proposed strongest user collision resolution protocol for XL-MIMO (SUCRe-XL) presents a bias since devices closer to the base station (BS) are favored, while those farther ones are rejected, leading to poor connectivity and excessive access delays to most users not very close to the BS. The novel RA protocol for XL-MIMO scenarios proposed in this article is based on access class barring with power control (ACBPC). Exploring the visibility regions (VRs) intrinsic to XL-MIMO scenarios as a new degree of freedom, the proposed grant-based ACBPC-XL protocol can improve the probability of resolving pilot collisions. The protocol is able to manage a higher number of users in crowded applications, diminishing the access delay while improving connectivity fairness along the entire cell area since the access performance does not depend on the distance between users and BS. Numerical results indicate that in average <inline-formula><tex-math notation="LaTeX">\approx </tex-math></inline-formula> 76% of users have improved connectivity when employing the ACBPC-XL instead of the SUCRe-XL protocol.