Stefano Buzzi

Stefano Buzzi
Università degli studi di Cassino e del Lazio Meridionale | UNICAS · Department of Electrical and Information Engineering

PhD in Electrical and Computer Engineering

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147
Publications
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Publications

Publications (147)
Article
The use of base stations (BSs) and access points (APs) with a large number of antennas, called Massive MIMO (multiple-input multiple-output), is a key technology for increasing the capacity of 5G networks and beyond. While originally conceived for conventional sub-6\,GHz frequencies, Massive MIMO (mMIMO) is ideal also for frequency bands in the ran...
Article
Future cellular systems based on the use of millimeter waves will heavily rely on the use of antenna arrays both at the transmitter and at the receiver. For complexity reasons and energy consumption issues, fully digital precoding and postcoding structures may turn out to be unfeasible, and thus suboptimal structures, making use of simplified hardw...
Article
This paper presents results on the achievable spectral efficiency and on the energy efficiency for a wireless multiple-input-multiple-output (MIMO) link operating at millimeter wave frequencies (mmWave) in a typical 5G scenario. Two different single-carrier modem schemes are considered, i.e., a traditional modulation scheme with linear equalization...
Conference Paper
In a cell-free (CF) massive MIMO architecture a very large number of distributed access points (APs) simultaneously and jointly serves a much smaller number of mobile stations (MSs); a variant of the cell-free technique is the user-centric (UC) approach, wherein each AP just decodes a reduced set of MSs, practically the ones that are received best....
Conference Paper
Full-text available
Recently, the so-called cell-free Massive MIMO architecture has been introduced, wherein a very large number of distributed access points (APs) simultaneously and jointly serve a much smaller number of mobile stations (MSs); each AP uses local channel estimates obtained from received uplink pilots and applies channel inversion beamforming to transm...
Article
In a cell-free (CF) massive MIMO architecture a very large number of distributed access points (APs) simultaneously and jointly serves a much smaller number of mobile stations (MSs); a variant of the cell-free technique is the user-centric (UC) approach, wherein each AP just decodes a reduced set of MSs, practically the ones that are received best....
Article
Recently, the so-called cell-free Massive MIMO architecture has been introduced, wherein a very large number of distributed access points (APs) simultaneously and jointly serve a much smaller number of mobile stations (MSs). A variant of the cell-free technique is the user-centric approach, wherein each AP just decodes the MSs that it receives with...
Article
Full-text available
Recently, the so-called cell-free Massive MIMO architecture has been introduced, wherein a very large number of distributed access points simultaneously and jointly serve a much smaller number of mobile stations. This paper introduces a user-centric virtual cell approach to cell-free massive MIMO, wherein each user is served only by a limited numbe...
Article
Full-text available
This paper focuses on multiuser MIMO channel estimation and data transmission at millimeter wave (mmWave) frequencies. The proposed approach relies on the time-division-duplex (TDD) protocol and is based on two distinct phases. First of all, the Base Station (BS) sends a suitable probing signal so that all the Mobile Stations (MSs), using a subspac...
Article
This paper proposes the use of subspace tracking algorithms for performing MIMO channel estimation at millimeter wave (mmWave) frequencies. Using a subspace approach, we develop a protocol enabling the estimation of the right (resp. left) singular vectors at the transmitter (resp. receiver) side; then, we adapt the projection approximation subspace...
Article
Full-text available
Enhanced mobile broadband (eMBB) is one of the key use-cases for the development of the new standard 5G New Radio for the next generation of mobile wireless networks. Large-scale antenna arrays, a.k.a. Massive MIMO, the usage of carrier frequencies in the range 10-100 GHz, the so-called millimeter wave (mm-wave) band, and the network densification...
Article
Full-text available
Future cellular systems based on the use of above-6 GHz frequencies, the so-called millimeter wave (mmWave) bandwidths, will heavily rely on the use of antenna arrays both at the transmitter and at the receiver, possibly with a large number of elements. For complexity reasons, fully digital precoding and postcoding structures may turn out to be unf...
Chapter
This chapter reviews some of the best recently proposed alternatives to orthogonal frequency division multiplexing (OFDM). It gives mathematical models and block&;#x02010;schemes of the transmitter for all the alternatives considered. The chapter provides a comparative analysis of these modulations, highlights their pros and cons, and discusses the...
Chapter
This chapter proposes the device&;#x02010;to&;#x02010;device (D2D) communication paradigm to better utilize the spectrum. The energy&;#x02010;efficient resource allocation problem in D2D systems for energy proportionality is considered as a case study for the application of the outlined sequential fractional programming algorithms. The chapter cons...
Article
Full-text available
One of the key features of next generation wireless communication systems will be the use of frequencies in the range 10-100GHz (aka mmWave band) in densely populated indoor and outdoor scenarios. Due to the reduced wavelength, antenna arrays with a large number of antennas can be packed in very small volumes, making thus it possible to consider, a...
Article
Full-text available
The use of mmWave frequencies is one of the key strategies to achieve the fascinating 1000x increase in the capacity of future 5G wireless systems. While for traditional sub-6 GHz cellular frequencies several well-developed statistical channel models are available for system simulation, similar tools are not available for mmWave frequencies, thus p...
Article
Full-text available
Future wireless networks will extensively rely upon bandwidths centered on carrier frequencies larger than 10GHz. Indeed, recent research has shown that, despite the large path-loss, millimeter wave (mmWave) frequencies can be successfully exploited to transmit very large data-rates over short distances to slowly moving users. Due to hardware compl...
Article
The issue of energy-aware resource allocation in an amplify-and-forward (AF) relay-assisted multiple-antenna interference channel (IC) is considered. A novel interference neutralization (IN) scheme is proposed for relay design and, based on the IN relay matrix design, two algorithms are developed to jointly allocate the users' transmit powers, beam...
Article
In this paper, the issue of energy-aware competitive resource allocation in an amplify-and-forward (AF) relay-assisted multiple-antenna interference network is considered. A non-cooperative game-theoretic approach is taken and the EE of each communication link is defined as the ratio of the achievable rate over the consumed power. The proposed reso...
Article
Fifth-generation (5G) cellular communications promise to deliver the gigabit experience to mobile users, with a capacity increase of up to three orders of magnitude with respect to current long-term evolution (LTE) systems. There is widespread agreement that such an ambitious goal will be realized through a combination of innovative techniques invo...
Article
5G cellular communications promise to deliver the gigabit experience to mobile users, with a capacity increase of up to three orders of magnitude with respect to current LTE systems. There is widespread agreement that such an ambitious goal will be realized through a combination of innovative techniques involving different network layers. At the ph...
Conference Paper
This work addresses the problem of coordinated beamforming in the downlink of an OFDMA cellular network. The figure of merit to be optimized is the global energy efficiency, defined as the ratio between the sum-rate of the coordinated base stations and the corresponding power consumption, under a per-base-station power constraint. The Karush-Kuhn-T...
Article
Full-text available
What will 5G be? What it will not be is an incremental advance on 4G. The previous four generations of cellular technology have each been a major paradigm shift that has broken backwards compatibility. And indeed, 5G will need to be a paradigm shift that includes very high carrier frequencies with massive bandwidths, extreme base station and device...
Article
Full-text available
This paper addresses the problem of energy-efficient resource allocation in the downlink of a cellular OFDMA system. Three definitions of the energy efficiency are considered for system design, accounting for both the radiated and the circuit power. User scheduling and power allocation are optimized across a cluster of coordinated base stations wit...
Article
This paper addresses the problem of coordinated beamforming across a group of base stations (BSs) and frequency slots in the downlink of a multiple-input multiple-output (MIMO) orthogonal frequency-division multiple-access (OFDMA) cellular network. Three figures of merit are considered for system design under a per-BS power constraint: 1) the weigh...
Article
Full-text available
A network of radars sharing the same frequency band, and using properly coded waveforms to improve features attractive from the radar point of view is considered in this article. Non-cooperative games aimed at code design for maximization of the signal-to-interference plus noise ratio (SINR) of each active radar are presented. Code update strategie...
Conference Paper
This paper considers the problem of energy-efficient communication in the downlink of a cellular OFDMA network. User scheduling and power allocation are jointly optimized across a cluster of coordinated base stations so as to maximize the weighted sum of the energy efficiencies on the available resource slots under a per-subcarrier power constraint...
Conference Paper
Recent research on game-theoretic approaches for non-cooperative resource allocation in relay-assisted interference channels is reviewed in this paper. The considered utility function is the physical layer energy efficiency, which is measured in bit/J, and denotes the number of bits successfully delivered to the receiver for each energy unit draine...
Article
Full-text available
Resource allocation for energy efficiency optimization in multi-carrier interference networks with multiple receive antennas is tackled. First, a one-hop network is considered, and then, the results are extended to the case of a two-hop network in which amplify-and-forward relaying is employed to enable communication. A distributed algorithm which...
Conference Paper
In this paper strategies to enhance the performance, in terms of available data-rate per user, energy efficiency, and spectral efficiency, of current DSL lines are proposed. In particular, a system wherein a group of copper wires is jointly processed at both ends of the communication link is considered. For such a scenario, (a) the statistical mult...
Conference Paper
In this paper, the issue of competitive, energy- efficient power control in a relay-assisted interference channel is considered. The energy efficiency is measured in bit/Joule and is defined as the ratio of a SINR-based function, divided by the sum of the transmit power plus the circuit power consumed to operate the device. Taking also into account...
Article
Competitive power control for energy efficiency maximization in wireless interference networks is addressed, for the scenarios in which the users' SINR can be expressed as either (a) γ = (αp)/(φp + ω), or (b) γ = (αp + βp2)/(φp + ω), with p the user's transmit power. The considered SINR expressions naturally arise in relay-assisted systems. The ene...
Article
Full-text available
We propose a new spread spectrum (SS) system based on continuous-phase modulations (CPMs). The main idea is to exploit the sequence of modulation indices of a multi-h CPM as a frequency-hopping (FH) sequence. Spectral spreading, flatness and smoothness can be easily achieved by an appropriate choice of the maximum value of the modulation index and...
Conference Paper
Energy-efficient resource allocation in the downlink of a multi-cell OFDMA-based cellular system with base station coordination is considered in this paper. Using the tools of fractional programming and alternating maximization, user scheduling on subcarriers and transmit power allocation is carried out in order to maximize a system-wide energy-eff...
Conference Paper
Full-text available
This paper briefly describes the objectives of the TREND (Toward Real Energy-efficient Network Design) Network of Excellence of the European Commission 7th Framework Programme, and outlines some of the main results obtained so far within the project, looking at wireless access networks, core networks, and content distribution issues.
Conference Paper
The issue of non-cooperative, energy-efficient power control in a relay-assisted interference channel is tackled in this paper, based on a game-theoretic approach. A pricing-based utility function is considered, in which the price controls the trade-off between maximizing the achievable rate and saving as much battery power as possible. Unlike most...
Conference Paper
In this paper, the issue of non-cooperative, energy-efficient power control in a relay-assisted interference channel is considered. The energy efficiency of a given terminal is defined as the ratio between the throughput of that terminal and the consumed power. As far as the computation of the consumed power is concerned, not only the transmit powe...
Article
In this paper, the issue of non-cooperative, green resource allocation in a multicarrier relay-assisted interference channel is considered. The energy efficiency of a given terminal is defined as the ratio between the throughput of that terminal and the consumed power. Unlike many previous contributions, as far as the computation of the consumed po...
Article
The problem of noncooperative resource allocation in multicell uplink orthogonal frequency division multiple access (OFDMA) systems is considered in this paper. Noncooperative games for subcarrier allocation and transmit power control are considered, aiming at maximizing the users' SINRs and, most notably, the users' energy efficiency, measured in...
Conference Paper
In this paper, non-cooperative, energy-efficient resource allocation in a MIMO relay-assisted interference channel is considered. The energy efficiency of a given terminal is defined as the ratio between the throughput of that terminal and the consumed power. As far as the computation of the consumed power is concerned, not only the transmit power,...
Article
Green resource allocation for relay-assisted DS/CDMA interference channels is considered in this paper. A non-cooperative game-theoretic approach is taken, according to which each user is selfishly interested in maximizing his own energy efficiency, measured in bit/Joule and denoting the number of error-free delivered bits for each energy-unit used...
Conference Paper
Full-text available
This study examines the error distribution of aggregated MPDUs in 802.11n networks and whether or not forward error correction like raptor coding at the link layer would be useful in these networks. Several experiments with Qualcomm 4×4 802.11n ...
Conference Paper
Conference code: 87696, Export Date: 25 July 2012, Source: Scopus, Art. No.: 6082513, doi: 10.1109/GreenCom.2011.6082513, Language of Original Document: English, Correspondence Address: Buzzi, S.; Consorzio Nazionale Interuniversitario Per Le Telecomunicazioni (CNIT), DAEIMI, University of Cassino, Via G. Di Biasio, 43, I-03043 Cassino (FR), Italy;...
Conference Paper
The problem of non-cooperative resource allocation in multi-cell uplink OFDMA systems with multiple base station antennas is considered in this paper. Non-cooperative games for subcarrier allocation and transmit power control are considered, aiming at maximizing the users' energy efficiency, measured in bit/Joule and representing the number of erro...
Article
Non-cooperative power control strategies for the uplink of relay-assisted DS/CDMA wireless networks are considered in this paper using game-theoretic tools. Assuming that each user is interested in maximizing his own energy efficiency, measured in bit/Joule and denoting the number of error-free delivered bits for each energy-unit used for transmiss...
Article
The problem of noncooperative resource allocation in a multipoint-to-multipoint cellular network is considered in this paper. The considered scenario is general enough to represent several key instances of modern wireless networks such as a multicellular network, a peer-to-peer network (interference channel), and a wireless network equipped with fe...
Article
The uplink of a multiuser cognitive radio network, wherein secondary users communicating with a secondary access point coexist with primary users communicating with a primary access point, is considered in this paper. Primary and secondary users' signals coexist in the same frequency band, and the transmit powers of the secondary users are constrai...
Article
The uplink of a multiuser cognitive radio network, wherein secondary users communicating with a secondary access point coexist with primary users communicating with a primary access point, is considered in this paper. It is assumed that primary and secondary users' signals coexist in the same frequency band, and that the transmit powers of the seco...
Article
The issue of noncooperative transceiver optimization in the uplink of a multiuser wireless code division multiple access data network with widely linear detection at the receiver is considered. While previous work in this area has focused on a simple real signal model, in this paper, a baseband complex representation of the data is used so as to pr...
Article
Full-text available
The problem of non-cooperative spreading code allocation, linear receiver design, and transmit power control for multicell wireless networks is considered in this paper. Several utility functions to be maximized are considered, and, among them, we cite the received SINR, and the transmitter energy efficiency, which is measured in bit/Joule, and rep...
Article
In this letter, we investigate the problem of estimating the multipath signal delays in an asynchronous direct-sequence/code-division-multiple-access (DS/CDMA) system operating over a doubly-selective fading channel. A novel blind estimation procedure is proposed which only requires knowledge of the spreading code of the user of interest, but no pr...
Article
Full-text available
In this work, we consider the problem of detecting the presence of a new user in a direct-sequence/code-division-multiple-access (DS/CDMA) system with a doubly dispersive fading channel, and we propose a novel blind detection strategy that only requires knowledge of the spreading code of the user to be detected, but no prior information as to the t...
Article
This paper considers the issue of spreading code allocation and receiver optimization in a CDMA-based multiuser data network. Assuming that non-linear serial interference cancellation is performed at the receiver, the problem of noncooperative SINR maximization with respect to each user's spreading code and uplink receiver is first considered. It i...
Article
Full-text available
The problem of non-cooperative spreading code allocation, linear receiver design, and transmit power control for wire-less networks employing femtocells is considered in this pa-per. Several utility functions to be maximized are considered, and, among them, we cite the received SINR, and the trans-mitter energy efficiency, which is measured in bit/...
Article
This article provided a survey of waveform adaptation algorithms for multiuser wireless communications based on noncooperative game theory. Emphasis has been given to the problem of spreading code optimization in CDMA systems, a research topic that has attracted the interest of many researchers for years, and some space has also been devoted to oth...
Article
Full-text available
The issue of non-cooperative transceiver optimization in the uplink of a multiuser wireless code division multiple access data network with widely-linear detection at the receiver is considered. While previous work in this area has focused on a simple real signal model, in this paper a baseband complex representation of the data is used, so as to p...
Conference Paper
The issue of non-cooperative transceiver optimization in the uplink of a multiuser wireless data network with widely linear detection at the receiver is considered in this paper. While previous work in this area has focused on a simple real signal model, in this paper a baseband complex representation of the data is used, so as to properly take int...
Conference Paper
Full-text available
The problems of detecting the presence of a new user and of estimating the delays of its multipath replicas in a direct-sequence/code-division-multiple-access (DS/CDMA) system are investigated. Despite previous works, we consider a doubly-dispersive fading channel model and we propose a new code-aided detection algorithm which relies on the applica...
Article
This paper is focused on the cross-layer design problem of joint multiuser detection and power control for energy-efficiency optimization in wireless data networks through a game-theoretic approach. Unlike previous studies in this area, which have considered the application of game theory to achieve energy-efficiency in idealized synchronous code d...
Conference Paper
The issue of cross-layer spreading code optimization, widely-linear receiver choice and transmit power control for non-cooperative energy-efficiency maximization in CDMA-based wireless data networks is considered in this paper. While previous work in this area has focused on a simple real signal model, in this paper a baseband complex representatio...
Article
Full-text available
The issue of adaptive and distributed cross-layer resource allocation for energy efficiency in uplink code-division multiple-access (CDMA) wireless data networks is addressed. The resource allocation problems are formulated as noncooperative games wherein each terminal seeks to maximize its own energy efficiency, namely, the number of reliably tran...
Article
Full-text available
This paper is focused on the design and analysis of power control procedures for the uplink of multipath code-division-multiple-access (CDMA) channels based on the large system analysis (LSA). Using the tools of LSA, a new decentralized power control algorithm aimed at energy efficiency maximization and requiring very little prior information on th...
Article
Full-text available
This paper focuses on the cross-layer issue of resource allocation for energy efficiency in the uplink of a multiuser MIMO wireless communication system. Assuming that all of the transmitters and the uplink receiver are equipped with multiple antennas, the situation considered is that in which each terminal is allowed to vary its transmit power, be...
Article
This paper considers the problem of parameter estimation and data detection in multiuser bandlimited long-code DS/CDMA systems. Centralized (i.e., multiuser) and decentralized (i.e., single-user) estimation procedures for the delay, amplitude and phase offset of the users' CDMA received signals are derived. The proposed estimation procedures may be...
Article
Full-text available
This paper focuses on the cross-layer issue of joint multiuser detection and resource allocation for energy efficiency in wireless code-division multiple-access (CDMA) networks. In particular, assuming that a linear multiuser detector is adopted in the uplink receiver, the situation considered is that in which each terminal is allowed to vary its t...
Conference Paper
Full-text available
Power control is a fundamental task accomplished in any wireless cellular network; its aim is to set the transmit power of any mobile terminal, so that each user is able to achieve its own target SINR. While conventional power control algorithms require knowledge of a number of parameters of the signal of interest and of the multiaccess interferenc...
Conference Paper
This paper considers the problem of parameter estimation in multiuser bandlimited long-code DS/CDMA systems. Centralized (i.e., multiuser) and decentralized (i.e., single-user) estimation procedures for the delay, amplitude and phase offset of the users' CDMA received signals are derived. The proposed estimation procedures may be devised as two-ste...
Article
Full-text available
In this paper the issue of energy efficiency in CDMA wireless data networks is addressed through a game theoretic approach. Building on a recent paper by the first two authors, wherein a non-cooperative game for spreading-code optimization, power control, and receiver design has been proposed to maximize the ratio of data throughput to transmit pow...
Article
Full-text available
This paper focuses on the issue of energy efficiency in wireless data networks through a game theoretic approach. The case considered is that in which each user is allowed to vary its transmit power, spreading code, and uplink receiver in order to maximize its own utility, which is here defined as the ratio of data throughput to transmit power. In...
Article
Full-text available
This paper is focused on the cross-layer design problem of joint multiuser detection and power control for energy-efficiency optimization in a wireless data network through a game-theoretic approach. Building on work of Meshkati, et al., wherein the tools of game-theory are used in order to achieve energy-efficiency in a simple synchronous code div...
Conference Paper
This paper addresses the problem of early detection of K ges 1 multiple moving targets in radar systems through the use of track-before-detect (TBD) techniques. Assuming prior knowledge of K, a binary generalized likelihood ratio test (GLRT) is first derived, which shows that the multi-target TBD problem can be regarded as a K path trellis search....
Article
Full-text available
Power control is a fundamental task accomplished in any wireless cellular network; its aim is to set the transmit power of any mobile terminal, so that each user is able to achieve its own target SINR. While conventional power control algorithms require knowledge of a number of parameters of the signal of interest and of the multiaccess interferenc...
Conference Paper
Full-text available
This paper is focused on the cross-layer design problem of joint multiuser detection and power control for energy-efficiency optimization in a wireless data network through a game-theoretic approach. Building on work of Meshkati, et al., wherein the tools of game-theory are used in order to achieve energy-efficiency in a simple synchronous code div...
Chapter
Full-text available
A convolutionally coded CDMA data network wherein each user may transmit at one out of a set of possible data rates is considered in this chapter. The problem of joint detection of the data-rate of each user and of the corresponding information symbols is considered. In particular, it is shown here that the so-called turbo principle can be used als...