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In this paper, an underlay cognitive radio (CR) system is considered with multiple cognitive or secondary users contending to transmit their information to the cognitive destination (e.g., eNodeB) using the spectral resource of a primary…

Information Theory · Computer Science 2018-06-20 Neeraj Varshney , Prabhat K. Sharma , Mohamed Slim Alouini

We consider a cell-free massive multiple-input multiple-output (mMIMO) network, where unmanned aerial vehicles (UAVs) equipped with multiple antennas serve as distributed UAV-access points (UAV-APs). These UAV-APs provide seamless coverage…

Signal Processing · Electrical Eng. & Systems 2025-02-10 Neetu R. R , Ozan Alp Topal , Özlem Tuğfe Demir , Emil Björnson , Cicek Cavdar , Gourab Ghatak , Vivek Ashok Bohara

This paper focuses on the design of medium access control protocols for cognitive radio networks. The scenario in which a single cognitive user wishes to opportunistically exploit the availability of empty frequency bands within parts of…

Information Theory · Computer Science 2008-02-20 Lifeng Lai , Hesham El Gamal , Hai Jiang , H. Vincent Poor

Cell-free massive multiple-input multiple-output (MIMO) is a key technology for next-generation wireless systems. The integration of cell-free massive MIMO within the open radio access network (O-RAN) architecture addresses the growing need…

Signal Processing · Electrical Eng. & Systems 2026-05-04 Mohammad Hossein Shokouhi , Vincent W. S. Wong

In this letter, a new power allocation scheme is proposed to improve the reliability of cooperative non-orthogonal multiple access (CO-NOMA). The strong user is allocated the maximum power, whereas the weak user is allocated the minimum…

Signal Processing · Electrical Eng. & Systems 2020-11-26 Sana Riaz , Fahd Ahmed Khan , Sajid Saleem , Qasim Zeeshan Ahmed

We investigate an orthogonal frequency-division multiplexing (OFDM)-based downlink transmission scheme for large-scale multi-user (MU) multiple-input multiple-output (MIMO) wireless systems. The use of OFDM causes a high peak-to-average…

Information Theory · Computer Science 2012-09-06 Christoph Studer , Erik G. Larsson

In this paper, we consider a single-cell multi-user orthogonal frequency division multiple access (OFDMA) network with one unmanned aerial vehicle (UAV), which works as an amplify-and-forward relay to improve the quality-of-service (QoS) of…

Information Theory · Computer Science 2021-04-23 Shuhao Zeng , Hongliang Zhang , Boya Di , Lingyang Song

In this paper a unified approach for power allocation (PA) problem in multi-hop orthogonal frequency division multiplexing (OFDM) amplify-and-forward (AF) relaying systems has been developed. In the proposed approach, we consider short and…

Information Theory · Computer Science 2015-08-07 Amin Azari , Jalil S. Harsini , Farshad Lahouti

Wireless transmission using non-contiguous chunks of spectrum is becoming increasingly important due to a variety of scenarios such as: secondary users avoiding incumbent users in TV white space; anticipated spectrum sharing between…

Networking and Internet Architecture · Computer Science 2016-02-16 Muhammad Nazmul Islam , Narayan B. Mandayam , Sastry Kompella , Ivan Seskar

This paper studies distributed resource block (RB) allocation in wideband orthogonal frequency-division multiplexing (OFDM) cell-free systems. We propose a novel distributed sequential algorithm and its two variants, which optimize RB…

Signal Processing · Electrical Eng. & Systems 2025-03-11 Yang Ma , Shengqian Han , Chenyang Yang

This paper develops a sum-power minimized resource allocation (RA) algorithm subject to a sum-rate constraint for cooperative orthogonal frequency division modulation (OFDM) transmission with subcarrier-pair based opportunistic…

Information Theory · Computer Science 2016-11-15 Tao Wang , Yong Fang , Luc Vandendorpe

Cell-free massive MIMO (multiple-input multiple-output) enhances spectral and energy efficiency compared to conventional cellular networks by enabling joint transmission and reception across a large number of distributed access points…

Signal Processing · Electrical Eng. & Systems 2026-02-10 Özlem Tuğfe Demir , Emil Björnson

This paper studies cell-free massive multiple-input multiple-output (CF-mMIMO) systems that underpin simultaneous wireless information and power transfer (SWIPT) for separate information users (IUs) and energy users (EUs) in Internet of…

Information Theory · Computer Science 2025-05-08 Mohammadali Mohammadi , Le-Nam Tran , Zahra Mobini , Hien Quoc Ngo , Michail Matthaiou

The coupling between cell-free massive multiple-input multiple-output (MIMO) systems operating at millimeter-wave (mmWave) carrier frequencies and user mobility is considered in this paper. First of all, a mmWave channel is introduced…

Information Theory · Computer Science 2022-02-17 Carmen D'Andrea , Giovanni Interdonato , Stefano Buzzi

Cell-free Massive MIMO (mMIMO) is envisaged to be a next-generation technology beyond 5G with its high spectral efficiency and superior spatial diversity as compared to that of conventional MIMO technology. The main principle is that many…

Information Theory · Computer Science 2020-03-09 Zakir Hussain Shaik , Emil Björnson , Erik G. Larsson

Cell-Free Massive MIMO comprises a large number of distributed single-antenna access points (APs) serving a much smaller number of users. There is no partitioning into cells and each user is served by all APs. In this paper, the uplink…

Information Theory · Computer Science 2017-02-13 Elina Nayebi , Alexei Ashikhmin , Thomas L. Marzetta , Bhaskar D. Rao

In this paper, we consider a joint unicast and multi-group multicast cell-free distributed massive multiple-input multiple-output (MIMO) system, while accounting for co-pilot assignment strategy based channel estimation, pilot contamination…

Information Theory · Computer Science 2022-03-10 Jiamin Li , Qijun Pan , Zhenggang Wu , Pengcheng Zhu , Dongming Wang , Xiaohu You

It is a challenging task to design a random access protocol that achieves the optimal throughput in multi-cell random access with decentralized transmission due to the difficulty of coordination. In this paper, we present a decentralized…

Information Theory · Computer Science 2020-06-16 Huifa Lin , Kwang Soon Kim , Won-Yong Shin

A scalable framework is developed to allocate radio resources across a large number of densely deployed small cells with given traffic statistics on a slow timescale. Joint user association and spectrum allocation is first formulated as a…

Information Theory · Computer Science 2017-01-13 Binnan Zhuang , Dongning Guo , Ermin Wei , Michael L. Honig

In this paper, we investigate cell-free massive MIMO (CF-mMIMO) systems in which access points (APs) are equipped with fluid antennas (FAs) and develop a comprehensive framework for channel estimation, antenna port selection, and uplink…

Information Theory · Computer Science 2025-12-30 Maryam Olyaee , Giovanni Interdonato , Stefano Buzzi