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Unsourced random access (URA) has emerged as a pragmatic framework for next-generation distributed sensor networks. Within URA, concatenated coding structures are often employed to ensure that the central base station can accurately recover…

Information Theory · Computer Science 2021-12-02 Vamsi K. Amalladinne , Jamison R. Ebert , Jean-Francois Chamberland , Krishna R. Narayanan

This paper addresses the unsourced/uncoordinated random access problem in an integrated sensing and communications (ISAC) system, with a focus on uplink multiple access code design. Recent theoretical advancements highlight that an ISAC…

Information Theory · Computer Science 2025-04-25 Zhentian Zhang , Jian Dang , Kai-Kit Wong , Zaichen Zhang , Christos Masouros

This work explores the rate-reliability-complexity limits of the quasi-static K-user multiple access channel (MAC), with or without feedback. Using high-SNR asymptotics, the work first derives bounds on the computational resources required…

Information Theory · Computer Science 2015-06-03 Hsiao-feng , Lu , Petros Elia , Arun Singh

This paper investigates the massive random access for a huge amount of user devices served by a base station (BS) equipped with a massive number of antennas. We consider a grant-free unsourced random access (U-RA) scheme where all users…

Information Theory · Computer Science 2020-09-15 Xinyu Xie , Yongpeng Wu , Junyuan Gao , Wenjun Zhang

We consider unsourced random access (uRA) in a cell-free (CF) user-centric wireless network, where a large number of potential users compete for a random access slot, while only a finite subset is active. The random access users transmit…

Information Theory · Computer Science 2025-05-01 Burak Çakmak , Eleni Gkiouzepi , Manfred Opper , Giuseppe Caire

We investigate the coexistence of massive and critical Internet of Things (IoT) services in the context of the unsourced multiple access (UMA) framework introduced by Polyanskiy (2017), where all users employ a common codebook and the…

Information Theory · Computer Science 2023-10-16 Khac-Hoang Ngo , Giuseppe Durisi , Alexandre Graell i Amat , Petar Popovski , Anders E. Kalor , Beatriz Soret

We discuss the problem of designing channel access architectures for enabling fast, low-latency, grant-free and uncoordinated uplink for densely packed wireless nodes. Specifically, we study random-access codes, previously introduced for…

Information Theory · Computer Science 2019-07-23 Suhas S Kowshik , Kirill Andreev , Alexey Frolov , Yury Polyanskiy

We consider a communication system with multi-access fading channel. Each user in the system requires certain rate guarantee. Our main contribution is to devise a scheduling scheme called "Opportunistic Super-position Coding" that satisfies…

Information Theory · Computer Science 2009-11-24 Prasanna Chaporkar , Kimmo Kansanen , Ralf R. Müller

We study the problem of simulating a two-user multiple-access channel (MAC) over a multiple access network of noiseless links. Two encoders observe independent and identically distributed (i.i.d.) copies of a source random variable each,…

Information Theory · Computer Science 2023-12-08 Gowtham R. Kurri , Viswanathan Ramachandran , Sibi Raj B. Pillai , Vinod M. Prabhakaran

We analyze the performance of enhanced spread spectrum Aloha (E-SSA) in the framework of unsourced multiple access (UMAC). The asynchronous, unframed transmission of E-SSA is modified to enable a direct comparison with framed UMAC schemes…

Information Theory · Computer Science 2024-06-10 Riccardo Schiavone , Gianluigi Liva , Roberto Garello

Exponential error bounds achievable by universal coding and decoding are derived for frame-asynchronous discrete memoryless %asynchronous multiple access channels with two senders, via the method of subtypes, a refinement of the method of…

Information Theory · Computer Science 2020-02-04 Lóránt Farkas , Tamás Kói

In this paper, a novel uncoordinated random access (URA) protocol is presented to address the pressing demand for massive connectivity with low access latency in future massive machine type communication (mMTC) scenarios. The proposed URA…

Signal Processing · Electrical Eng. & Systems 2025-10-28 Pengyu Gao , Qu Luo , Jing Zhu , Gaojie Chen , Pei Xiao , Chuan Heng Foh

Effective capacity, which provides the maximum constant arrival rate that a given service process can support while satisfying statistical delay constraints, is analyzed in a multiuser scenario. In particular, we study the achievable…

Information Theory · Computer Science 2009-10-22 Deli Qiao , Mustafa Cenk Gursoy , Senem Velipasalar

We study the Gaussian multiple access channel with random user activity, in the regime where the number of users is proportional to the code length. The receiver may know some statistics about the number of active users, but does not know…

Information Theory · Computer Science 2025-10-21 Xiaoqi Liu , Pablo Pascual Cobo , Ramji Venkataramanan

Polyanskiy proposed a framework for the unsourced multiple access channel (MAC) problem where users employ a common codebook in the finite blocklength regime. However, existing approaches handle channel noise before the joint decoder. In…

Information Theory · Computer Science 2026-04-14 Yuming Han , Yuxin Long

Despite being the subject of a growing body of research, non-orthogonal multiple access has failed to garner sufficient support to be included in modern standards. One of the more promising approaches to non-orthogonal multiple access is…

Signal Processing · Electrical Eng. & Systems 2024-10-28 Dylan Wheeler , Erin E. Tripp , Balasubramaniam Natarajan

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

In distributed communication, each transmitter prepares an ensemble of channel codes. To encode a message, a transmitter chooses a channel code individually without sharing the coding choice with other transmitters or with the receiver.…

Information Theory · Computer Science 2018-05-08 Yanru Tang , Faeze Heydaryan , Jie Luo

Several security models of multiple-access channel (MAC) are investigated. First, we study the degraded MAC with confidential messages, where two users transmit their confidential messages (no common message) to a destination, and each user…

Information Theory · Computer Science 2013-01-01 Bin Dai , A. J. Han Vinck , Zhuojun Zhuang , Yuan Luo

We consider unsourced random access with MIMO receiver - a crucial communication scenario for future 5G/6G wireless networks. We perform a projection-based decoder analysis and derive energy efficiency achievability bounds when channel…

Information Theory · Computer Science 2023-03-28 Kirill Andreev , Daria Ustinova , Alexey Frolov