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In this work, we discuss the problem of unsourced random access (URA) over a Gaussian multiple access channel (GMAC). To address the challenges posed by emerging massive machine-type connectivity, URA reframes multiple access as a…

Information Theory · Computer Science 2025-05-06 Zhentian Zhang , Mohammad Javad Ahmadi , Jian Dang , Kai-Kit Wong , Zaichen Zhang , Christos Masouros

Unsourced random access (URA) has emerged as a candidate paradigm for massive machine-type communication (MTC) in next-generation wireless networks. While many excellent uplink schemes have been developed for URA, these schemes do not…

Information Theory · Computer Science 2022-06-06 Jamison R. Ebert , Krishna R. Narayanan , Jean-Francois Chamberland

Cell-Free Massive MIMO systems aim to expand the coverage area of wireless networks by replacing a single high-performance Access Point (AP) with multiple small, distributed APs connected to a Central Processing Unit (CPU) through a…

Information Theory · Computer Science 2023-11-13 Michail Gkagkos , Jean-Francois Chamberland , Costas N. Georghiades , Krishna R. Narayanan

Unsourced random access (URA) is a recently proposed multiple access paradigm tailored to the uplink channel of machine-type communication networks. By exploiting a strong connection between URA and compressed sensing, the massive multiple…

Information Theory · Computer Science 2022-06-28 Jamison R. Ebert , Vamsi K. Amalladinne , Stefano Rini , Jean-Francois Chamberland , Krishna R. Narayanan

We investigate fully asynchronous unsourced random access (URA), and propose a high-performing scheme that employs on-off division multiple access (ODMA). In this scheme, active users distribute their data over the transmit block based on a…

Signal Processing · Electrical Eng. & Systems 2025-04-16 Mert Ozates , Mohammad Kazemi , Gianluigi Liva , Deniz Gündüz

A joint sparse-regression-code (SPARC) and low-density-parity-check (LDPC) coding scheme for multiple-input multiple-output (MIMO) massive unsourced random access (URA) is proposed in this paper. Different from the state-of-the-art…

Information Theory · Computer Science 2022-01-12 Tianya Li , Yongpeng Wu , Mengfan Zheng , Dongming Wang , Wenjun Zhang

In this paper, we investigate an unsourced random access scheme for massive machine-type communications (mMTC) in the sixth-generation (6G) wireless networks with sporadic data traffic. Firstly, we establish a general framework for massive…

Information Theory · Computer Science 2022-03-01 Feiyan Tian , Xiaoming Chen , Lei Liu , Derrick Wing Kwan Ng

We study the problem of unsourced random access (URA) over Rayleigh block-fading channels with a receiver equipped with multiple antennas. We propose a slotted structure with multiple stages of orthogonal pilots, each of which is randomly…

Information Theory · Computer Science 2023-07-17 Mohammad Javad Ahmadi , Mohammad Kazemi , Tolga M. Duman

Code-expanded Random Access (CeRA) is a promising technique for supporting mMTC in cellular IoT networks. However, its potentiality is limited by code ambiguity, which results from the inference of a larger number of codewords than those…

Information Theory · Computer Science 2021-05-28 Carlos A. Astudillo , Ekram Hossain , Nelson L. S. da Fonseca

We consider unsourced random access (uRA) in user-centric cell-free (CF) wireless networks, where random access users send codewords from a common codebook during specifically dedicated random access channel (RACH) slots. The system is…

Information Theory · Computer Science 2024-08-16 Eleni Gkiouzepi , Burak Çakmak , Manfred Opper , Giuseppe Caire

This paper investigates the energy efficiency of massive unsourced random access~(URA) in multiple-input multiple-output quasi-static Rayleigh fading channels. Specifically, we derive achievability and converse bounds on the minimum…

Information Theory · Computer Science 2023-02-07 Junyuan Gao , Yongpeng Wu , Tianya Li , Wenjun Zhang

This paper considers an unsourced random access (URA) set-up equipped with a passive reconfigurable intelligent surface (RIS), where a massive number of unidentified users (only a small fraction of them being active at any given time) are…

Information Theory · Computer Science 2024-08-27 Mohammad Javad Ahmadi , Mohammad Kazemi , Tolga M. Duman

This paper is a tutorial introduction to the field of unsourced multiple access (UMAC) protocols. We first provide a historical survey of the evolution of random access protocols, focusing specifically on the case in which uncoordinated…

Information Theory · Computer Science 2024-08-20 Gianluigi Liva , Yury Polyanskiy

In this paper, we investigate a joint device activity detection (DAD), channel estimation (CE), and data decoding (DD) algorithm for multiple-input multiple-output (MIMO) massive unsourced random access (URA). Different from the…

Information Theory · Computer Science 2021-12-20 Tianya Li , Yongpeng Wu , Mengfan Zheng , Wenjun Zhang , Chengwen Xing , Jianping An , Xiang-Gen Xia , Chengshan Xiao

Type-based unsourced multiple access (TUMA) is a recently proposed framework for type-based estimation in massive uncoordinated access networks. We extend the existing design of TUMA, developed for an additive white Gaussian channel, to a…

Information Theory · Computer Science 2025-04-29 Kaan Okumus , Khac-Hoang Ngo , Giuseppe Durisi , Erik G. Ström

A high success rate of grant-free random access scheme is proposed to support massive access for machine-to-machine communications in massive multipleinput multiple-output systems. This scheme allows active user equipments (UEs) to transmit…

Information Theory · Computer Science 2020-12-29 Huimei Han , Lushun Fang , Weidang Lu , Wenchao Zhai , Ying Li , Jun Zhao

We consider the problem of type estimation over unsourced multiple access fading channels in distributed multiple-input multiple-output (D-MIMO) systems. Unlike classical unsourced multiple access, type-based unsourced multiple access…

Information Theory · Computer Science 2026-03-03 Kaan Okumus , Khac-Hoang Ngo , Giuseppe Durisi , Erik G. Ström

This work introduces security for unsourced random access (URA) by employing physical layer security techniques. To achieve confidentiality, the proposed system opportunistically exploits intrinsic features of feedback-aided URA without…

Information Theory · Computer Science 2026-03-26 Mohammad Javad Ahmadi , Rafael F. Schaefer , H. Vincent Poor

In this paper, we investigate unsourced random access for massive machine-type communications (mMTC) in the sixth-generation (6G) wireless networks. Firstly, we establish a high-efficiency uncoupled framework for massive unsourced random…

Information Theory · Computer Science 2024-05-07 Feiyan Tian , Xiaoming Chen , Yong Liang Guan , Chau Yuen

This paper explores the fundamental limits of unsourced random access (URA) with a random and unknown number ${\rm{K}}_a$ of active users in MIMO quasi-static Rayleigh fading channels. First, we derive an upper bound on the probability of…

Information Theory · Computer Science 2024-04-16 Junyuan Gao , Yongpeng Wu , Giuseppe Caire , Wei Yang , Wenjun Zhang