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A new universal coding/decoding scheme for random access with collision detection is given in the case of two senders. The result is used to give an achievable joint source-channel coding error exponent for multiple access channels in the…

Information Theory · Computer Science 2013-09-19 Lóránt Farkas , Tamás Kói

Interferences arising between wireless sensor-actuator systems communicating over shared wireless channels adversely affect closed loop control performance. To mitigate this problem we design appropriate channel access policies for wireless…

Optimization and Control · Mathematics 2018-10-30 Konstantinos Gatsis , Alejandro Ribeiro , George J. Pappas

We consider an unsourced random access (URA) system enhanced with a feedback mechanism that serves both communication and sensing tasks. While traditional URA systems do not incorporate feedback, we propose a novel feedback signal design…

Information Theory · Computer Science 2025-06-26 Mohammad Javad Ahmadi , Mohammad Kazemi , Rafael F. Schaefer

This paper investigates the unsourced random access (URA) scheme to accommodate numerous machine-type users communicating to a base station equipped with multiple antennas. Existing works adopt a slotted transmission strategy to reduce…

Information Theory · Computer Science 2022-02-17 Xinyu Xie , Yongpeng Wu , Jianping An , Junyuan Gao , Wenjun Zhang , Chengwen Xing , Kai-Kit Wong , Chengshan Xiao

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 paper investigates downlink transmission over a quasi-static fading Gaussian broadcast channel (BC), to model delay-sensitive applications over slowly time-varying fading channels. System performance is characterized by outage…

Information Theory · Computer Science 2007-11-13 Wenyi Zhang , Shivaprasad Kotagiri , J. Nicholas Laneman

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

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

In \cite{Chandar2008}, Chandar et al studied a problem of sequential frame synchronization for a frame transmitted randomly and uniformly among $A$ slots. For a discrete memory-less channel (DMC), they showed that the frame length $N$ must…

Information Theory · Computer Science 2015-06-24 R. M. Sundaram , Devendra Jalihal , Venkatesh Ramaiyan

To account for the massive uncoordinated random access scenario, which is relevant for the Internet of Things, Polyanskiy (2017) proposed a novel formulation of the multiple-access problem, commonly referred to as unsourced multiple access,…

Information Theory · Computer Science 2023-02-23 Khac-Hoang Ngo , Alejandro Lancho , Giuseppe Durisi , Alexandre Graell i Amat

In this paper, a downlink scenario in which a single-antenna base station communicates with K single antenna users, over a time-correlated fading channel, is considered. It is assumed that channel state information is perfectly known at…

Information Theory · Computer Science 2007-07-13 Mehdi Ansari Sadrabadi , Alireza Bayesteh , Amir K. Khandani

This paper considers a random access system where each sender can be in two modes of operation, active or not active, and where the set of active users is available to a common receiver only. Active transmitters encode data into independent…

Information Theory · Computer Science 2016-11-18 Paolo Minero , Massimo Franceschetti , David N. C. Tse

Unsourced random-access (U-RA) is a type of grant-free random access with a virtually unlimited number of users, of which only a certain number $K_a$ are active on the same time slot. Users employ exactly the same codebook, and the task of…

Information Theory · Computer Science 2021-12-10 Alexander Fengler , Peter Jung , Giuseppe Caire

We consider the problem of transmission of several distributed sources over a multiple access channel (MAC) with side information at the sources and the decoder. Source-channel separation does not hold for this channel. Sufficient…

Information Theory · Computer Science 2008-03-11 R. Rajesh , Vinod Sharma

Unsourced random access is a novel communication paradigm designed for handling a large number of uncoordinated users that sporadically transmit very short messages. Under this model, coded compressed sensing (CCS) has emerged as a…

Information Theory · Computer Science 2021-07-22 Jamison R. Ebert , Vamsi K. Amalladinne , Stefano Rini , Jean-Francois Chamberland , Krishna R. Narayanan

We consider coded caching over the fading broadcast channel, where the users, equipped with a memory of finite size, experience asymmetric fading statistics. It is known that a naive application of coded caching over the channel at hand…

Information Theory · Computer Science 2018-01-16 Richard Combes , Asma Ghorbel , Mari Kobayashi , Sheng Yang

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 addresses an interference channel consisting of $\mathbf{n}$ active users sharing $u$ frequency sub-bands. Users are asynchronous meaning there exists a mutual delay between their transmitted codes. A stationary model for…

Information Theory · Computer Science 2010-06-17 Kamyar Moshksar , Amir K. Khandani

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

In this paper, we consider uplink transmissions involving multiple users communicating with a base station over a fading channel. We assume that the base station does not coordinate the transmissions of the users and hence the users employ…

Computer Science and Game Theory · Computer Science 2009-08-25 Nitin Salodkar , Abhay Karandikar