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Ardah, K., Fodor, G., Silva, Y. C. B., Freitas Jr, W. C. & de Almeida, A. L. F. (2020). Hybrid Analog-Digital Beamforming Design for SE and EE Maximization in Massive MIMO Networks. IEEE Transactions on Vehicular Technology, 69(1), 377-389
Open this publication in new window or tab >>Hybrid Analog-Digital Beamforming Design for SE and EE Maximization in Massive MIMO Networks
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2020 (English)In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 69, no 1, p. 377-389Article in journal (Refereed) Published
Abstract [en]

Hybrid analog-digital (HAD) beamforming architectures have been proposed to facilitate the practical implementation of massive multiple-input multiple-output (MIMO) systems by reducing the number of employed radio frequency chains. While most prior studies have aimed to maximize spectral efficiency (SE), the present paper proposes a two-stage HAD beamforming design for multi-user MIMO systems that can be used to maximize either the system's overall energy efficiency (EE) or SE. This problem is nonconvex and NP-hard due to the joint optimization between the analog and digital domains and the constant modulus constraints required by the analog domain. To address this problem, we propose a decoupled two-stage design wherein the first stage, the analog beamforming parts are updated, which are then taken into account in the second stage to design the digital beamforming parts to maximize the system's EE or SE. We consider two widely-used HAD beamforming techniques that utilize either fully-connected (FC) or partially-connected (PC) architectures employing variable phase-shifters. Using the most recently available data for the circuitry power consumption of the components, we compare the performance of these two HAD architectures with that of the fully-digital (FD) architecture in terms of the total circuitry power consumption, and achieved SE and EE. We find that there is a certain number of users above which the FC architecture has higher circuitry power consumption than the FD counterpart, in contrast to the PC architecture that always has lower circuitry power consumption. More importantly, our results reveal, contrary to the common opinion, that depending on the circuitry parameters the FD architecture may achieve not only higher SE, but also higher EE than the HAD architectures.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2020
Keywords
Hybrid analog-digital, MIMO, spectral/energy efficiency maximization
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-269500 (URN)10.1109/TVT.2019.2933305 (DOI)000512550600032 ()2-s2.0-85078825956 (Scopus ID)
Note

QC 20200309

Available from: 2020-03-09 Created: 2020-03-09 Last updated: 2020-03-09Bibliographically approved
Della Penda, D., Wichman, R., Charalambous, T., Fodor, G. & Johansson, M. (2019). A Distributed Mode Selection Scheme for Full-Duplex Device-to-Device Communication. IEEE Transactions on Vehicular Technology, 68(10), 10267-10271
Open this publication in new window or tab >>A Distributed Mode Selection Scheme for Full-Duplex Device-to-Device Communication
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2019 (English)In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 68, no 10, p. 10267-10271Article in journal (Refereed) Published
Abstract [en]

Networks with device-to-device(D2D) technology allow for two possible communication modes: traditional communication via the base station, and direct communication between the users. Recent studies show that in-band full-duplex(IBFD) operations can be advantageously combined with D2D communication to improve the spectral efficiency. However, no algorithms for selecting the communication mode of mobile users in IBFD networks have yet appeared in the literature. In this paper, we design a distributed mode selection scheme for users in D2D-enabled IBFD networks. The proposed scheme maximizes the users prob-ability of successful communication by leveraging only existing signaling mechanisms.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Keywords
Device-to-device communication, Base stations, Interference, Geometry, Energy measurement, Throughput, Complexity theory, mobile communication, decision theory, full-duplex, sequential test
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-266169 (URN)10.1109/TVT.2019.2932046 (DOI)000501349900075 ()2-s2.0-85073880431 (Scopus ID)
Note

QC 20200113

Available from: 2020-01-13 Created: 2020-01-13 Last updated: 2020-01-13Bibliographically approved
Zhao, P., Fodor, G., Dán, G. & Telek, M. (2019). A Game Theoretic Approach to Uplink Pilot and Data Power Control in Multi-Cell Multi-User MIMO Systems. IEEE Transactions on Vehicular Technology, 68(9), 8707-8720
Open this publication in new window or tab >>A Game Theoretic Approach to Uplink Pilot and Data Power Control in Multi-Cell Multi-User MIMO Systems
2019 (English)In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 68, no 9, p. 8707-8720Article in journal (Refereed) Published
Abstract [en]

In multi-user multiple-input-multiple-output (MU-MIMO) systems that employ pilot-symbol aided channel estimation, the pilot-to-data power ratio (PDPR) has a large impact on the system performance. In this paper, we consider the problem of setting the PDPR in multi-cell MU-MIMO systems in the presence of channel estimation errors, intercell interference and pilot contamination. To analyze and address this problem, we first develop a model of the multi-cell MU-MIMO system and derive a closed-form expression for the mean squared error of the uplink received data symbols. Building on this result, we then propose two decentralized PDPR-setting algorithms based on game theoretic approaches that are applicable in multi-cell systems. We find that both algorithms converge to a Nash equilibrium and provide performance improvements over systems that do not properly set the PDPR, while they maintain different levels of fairness.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2019
Keywords
Multi-antenna systems, channel state information, estimation techniques, receiver algorithms
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-261969 (URN)10.1109/TVT.2019.2927127 (DOI)000487191500036 ()2-s2.0-85077498421 (Scopus ID)
Note

QC 20191014

Available from: 2019-10-14 Created: 2019-10-14 Last updated: 2020-03-09Bibliographically approved
Guimaraes, F. R., Fodor, G., Freitas, W. C. & Silva, Y. C. (2019). A Multi-Stream Pricing-Based Precoding and Power Control Algorithm for Dynamic TDD Networks. In: 2019 IEEE Conference on Standards for Communications and Networking, CSCN 2019: . Paper presented at 2019 IEEE Conference on Standards for Communications and Networking, CSCN 2019, Granada, Spain, October 28-30, 2019. Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>A Multi-Stream Pricing-Based Precoding and Power Control Algorithm for Dynamic TDD Networks
2019 (English)In: 2019 IEEE Conference on Standards for Communications and Networking, CSCN 2019, Institute of Electrical and Electronics Engineers Inc. , 2019Conference paper, Published paper (Refereed)
Abstract [en]

Dynamic time division duplexing (DTDD) cellular networks enable to adapt the number of uplink and downlink time slots to the prevailing traffic demands in each cell at the expense of base station (BS)-to-BS and user equipment (UE)-to-UE interference. Recognizing the importance of mitigating the effect of these additional interference types, previous works proposed multicell coordinated beamforming to realize the full potential of DTDD systems that employ multiple antennas at the BSs. Unfortunately, the previously proposed mechanisms suffer from slow convergence, which renders such schemes impractical in fast fading and highly mobile environments. In this paper, we formulate the multicell multi-stream DTDD beamforming problem as an optimization task, and propose a near-optimal pricing-based algorithm to determine the beam directions and transmit power levels for each stream at the BSs. The proposed distributed precoding and power control algorithm not only improves the downlink performance, but it also substantially mitigates the BS-to-BS interference levels, and thereby improves the uplink performance as well. Simulation results indicate that the proposed algorithm exhibits faster convergence than previously proposed near-optimal schemes at the expense of some small performance degradation in terms of the achieved signal-to-interference-plus-noise-ratio (SINR).

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2019
Keywords
Beamforming, Costs, Mobile telecommunication systems, Signal interference, Signal to noise ratio, Time division multiplexing, Coordinated beamforming, Distributed pre-coding, Downlink performance, Interference level, Mobile environments, Near-optimal pricing, Performance degradation, Signal to interference plus noise ratio, Power control
National Category
Control Engineering
Identifiers
urn:nbn:se:kth:diva-268038 (URN)10.1109/CSCN.2019.8931407 (DOI)2-s2.0-85077821527 (Scopus ID)9781728108643 (ISBN)
Conference
2019 IEEE Conference on Standards for Communications and Networking, CSCN 2019, Granada, Spain, October 28-30, 2019
Note

QC 20200322

Available from: 2020-03-22 Created: 2020-03-22 Last updated: 2020-03-22Bibliographically approved
Cavalcante, E. d., Fodor, G., Silva, Y. C. B. & Freitas, W. C. . (2019). Bidirectional Sum-Power Minimization Beamforming in Dynamic TDD MIMO Networks. IEEE Transactions on Vehicular Technology, 68(10), 9988-10002
Open this publication in new window or tab >>Bidirectional Sum-Power Minimization Beamforming in Dynamic TDD MIMO Networks
2019 (English)In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 68, no 10, p. 9988-10002Article in journal (Refereed) Published
Abstract [en]

Employing dynamic time division duplexing can increase the system-wide spectral efficiency of applications with varying and unbalanced uplink and downlink data traffic requirements. However, in order to achieve this efficiency gain, it is necessary to manage the effects of cross-link interference, which are generated among cells transmitting in opposite link directions. This paper considers bidirectional sum-power minimization beamforming as a means to deal with this cross-link interference, by forcing a minimum signal-to-interference-plus-noise ratio constraint for both uplink and downlink. We propose two iterative approaches to solve this beamforming problem. The first approach assumes centralized processing and requires the availability of global channel state information. The second approach is performed in a decentralized manner, based on the alternating direction method of multipliers and requires only local channel state information and reduced signaling load. Both approaches are shown to converge to a minimum network power expenditure, whereas close-to-optimum performance can be obtained when limiting the number of iterations.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Keywords
Interference, Vehicle dynamics, Minimization, MIMO communication, Downlink, Dynamic scheduling, Optimization, Dynamic TDD, distributed beamforming, sum-power minimization
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-266181 (URN)10.1109/TVT.2019.2937474 (DOI)000501349900052 ()2-s2.0-85073870740 (Scopus ID)
Note

QC 20200110

Available from: 2020-01-10 Created: 2020-01-10 Last updated: 2020-01-10Bibliographically approved
Abrardo, A., Fodor, G. & Moretti, M. (2019). Distributed Digital and Hybrid Beamforming Schemes With MMSE-SIC Receivers for the MIMO Interference Channel. IEEE Transactions on Vehicular Technology, 68(7), 6790-6804
Open this publication in new window or tab >>Distributed Digital and Hybrid Beamforming Schemes With MMSE-SIC Receivers for the MIMO Interference Channel
2019 (English)In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 68, no 7, p. 6790-6804Article in journal (Refereed) Published
Abstract [en]

This paper addresses the problem of weighted sumrate maximization and mean squared error (MSE) minimization for the multiple-input multiple-output (MIMO) interference channel. Specifically, we consider a weighted minimum MSE architecture where each receiver employs successive interference cancellation (SIC) to separate the various received data streams and derive a hybrid beamforming scheme, where the transmitters operate with a number of radio frequency chains smaller than the number of antennas, particularly suited for millimeter-wave channels and 5G applications. To derive our proposed schemes, we first study the relationship between sum-rate maximization and weighted MSE minimization when using SIC receivers, assuming fully digital beamforming. Next, we consider the important-and, as it turns out, highly non-trivial-case where the transmitters employ hybrid digital/analog beamforming, developing a distributed joint hybrid precoding and SIC-based combining algorithm. Moreover, for practical implementation, we propose a signaling scheme that utilizes a common broadcast channel and facilitates the acquisition of channel state information, assuming minimal assistance from a central node such as a cellular base station. Numerical results show that both the proposed weighted MMSE-SIC schemes exhibit great advantages with respect to their linear counterparts in terms of complexity, feedback information, and performance.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Keywords
MIMO, weighted MSE minimization, successive interference cancellation, hybrid beamforming
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-255766 (URN)10.1109/TVT.2019.2918066 (DOI)000476775000046 ()2-s2.0-85069527149 (Scopus ID)
Note

QC 20190812

Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-08-12Bibliographically approved
Paiva, A. R., Fodor, G., Freitas, W. C., Silva, Y. C. & E Silva, C. F. (2019). Kalman-Filter-Based Tracking of Millimeter-Wave Channel Parameters for V2X Applications. In: 2019 IEEE Conference on Standards for Communications and Networking, CSCN 2019: . Paper presented at 2019 IEEE Conference on Standards for Communications and Networking, CSCN 2019, Granada, Spain, October 28-30, 2019. Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>Kalman-Filter-Based Tracking of Millimeter-Wave Channel Parameters for V2X Applications
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2019 (English)In: 2019 IEEE Conference on Standards for Communications and Networking, CSCN 2019, Institute of Electrical and Electronics Engineers Inc. , 2019Conference paper, Published paper (Refereed)
Abstract [en]

The spectrum of millimeter waves, when properly exploited, represents an important asset for achieving the high data rates and low latencies required by applications in vehicular communications. However, vehicle scenarios are characterized by high mobility, which results in frequent misalignment of beams. Therefore, in these types of scenarios, beam tracking algorithms are important because they can keep the beams aligned with a low training overhead. Kalman filters are strong candidates for the implementation of such algorithms, because they ensure high channel tracking performance over a wide range of signal-to-noise-ratios (SNR) and are easy to implement. This work evaluates the performance of channel tracking methods based on Kalman filters for high mobility. Our numerical results show that the proposed Kalman filter-based channel tracking method has high performance at low SNR regimes compared to least square-based methods, and improve the robustness when using planar instead of linear arrays. Moreover, the proposed channel tracking method is shown to perform well in multipath fading scenarios, while achieving high performance in the presence of strong line-of-sight components.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2019
Keywords
AoA, EnKF, MmWave, UKF, UPA, V2X, Kalman filters, Least squares approximations, Microwave filters, Millimeter waves, Numerical methods, Least-square-based methods, Line-of-sight components, mm-Wave, Numerical results, Tracking algorithm, Training overhead, Vehicular communications, Signal to noise ratio
National Category
Control Engineering
Identifiers
urn:nbn:se:kth:diva-268040 (URN)10.1109/CSCN.2019.8931350 (DOI)2-s2.0-85077811258 (Scopus ID)9781728108643 (ISBN)
Conference
2019 IEEE Conference on Standards for Communications and Networking, CSCN 2019, Granada, Spain, October 28-30, 2019
Note

 QC 20200322

Available from: 2020-03-22 Created: 2020-03-22 Last updated: 2020-03-22Bibliographically approved
Barros da Silva Jr., J. M., Sabharwal, A., Fodor, G. & Fischione, C. (2019). Low Resolution Phase Shifters Suffice for Full-Duplex mmWave Communications. In: 2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS): . Paper presented at IEEE International Conference on Communications (ICC), MAY 20-24, 2019, Shanghai, PEOPLES R CHINA. IEEE
Open this publication in new window or tab >>Low Resolution Phase Shifters Suffice for Full-Duplex mmWave Communications
2019 (English)In: 2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS), IEEE , 2019Conference paper, Published paper (Refereed)
Abstract [en]

Full-duplex base-stations with half-duplex nodes, allowing simultaneous uplink and downlink from different nodes, have the potential to double the spectrum efficiency without adding additional complexity at mobile nodes. Hybrid beam forming is commonly used in millimeter wave systems for its implementation efficiency. An important element of hybrid beam-forming is quantized phase shifters. In this paper, we ask if low-resolution phase shifters suffice for beamforming-based full-duplex millimeter wave systems. We formulate the problem of joint design for both self-interference suppression and downlink beamforming as an optimization problem, which we solve using penalty dual decomposition to obtain a near-optimal solution. Numerical results indicate that low-resolution phase shifters can perform close to systems that use infinite phase shifter resolution, and that even a single quantization bit outperforms half-duplex transmissions in both low and high residual self-interference scenarios.

Place, publisher, year, edition, pages
IEEE, 2019
Series
IEEE International Conference on Communications Workshops, ISSN 2164-7038
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-261051 (URN)10.1109/ICCW.2019.8756743 (DOI)000484917800046 ()2-s2.0-85070255997 (Scopus ID)978-1-7281-2373-8 (ISBN)
Conference
IEEE International Conference on Communications (ICC), MAY 20-24, 2019, Shanghai, PEOPLES R CHINA
Note

QC 20191002

Available from: 2019-10-02 Created: 2019-10-02 Last updated: 2019-10-02Bibliographically approved
Kant, S., Fodor, G., Bengtsson, M., Göransson, B. & Fischione, C. (2019). Low-Complexity OFDM Spectral Precoding. In: 20th IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC) 2019: . Paper presented at 20th IEEE International Workshop on Signal Processing Advances in Wireless Communications, SPAWC 2019; Cannes; France; 2 July 2019 through 5 July 2019. , Article ID 8815554.
Open this publication in new window or tab >>Low-Complexity OFDM Spectral Precoding
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2019 (English)In: 20th IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC) 2019, 2019, article id 8815554Conference paper, Published paper (Refereed)
Abstract [en]

This paper proposes a new large-scale mask compliant spectral precoder (LS-MSP) for orthogonal frequency division multiplexing systems. In this paper, we first consider a previously proposed mask-compliant spectral precoding scheme that utilizes a generic convex optimization solver which suffers from high computational complexity, notably in large-scale systems. To mitigate the complexity of computing the LS-MSP, we propose a divide-and-conquer approach that breaks the original problem into smaller rank 1 quadratic-constraint problems and each small problem yields closed-form solution. Based on these solutions, we develop three specialized first-order low-complexity algorithms, based on 1) projection on convex sets and 2) the alternating direction method of multipliers. We also develop an algorithm that capitalizes on the closed-form solutions for the rank 1 quadratic constraints, which is referred to as 3) semianalytical spectral precoding. Numerical results show that the proposed LS-MSP techniques outperform previously proposed techniques in terms of the computational burden while complying with the spectrum mask. The results also indicate that 3) typically needs 3 iterations to achieve similar results as 1) and 2) at the expense of a slightly increased computational complexity.

Keywords
Spectral Precoding, OFDM, 5G, mmWave
National Category
Signal Processing
Research subject
Telecommunication
Identifiers
urn:nbn:se:kth:diva-258067 (URN)10.1109/SPAWC.2019.8815554 (DOI)2-s2.0-85072337396 (Scopus ID)9781538665282 (ISBN)
Conference
20th IEEE International Workshop on Signal Processing Advances in Wireless Communications, SPAWC 2019; Cannes; France; 2 July 2019 through 5 July 2019
Funder
Swedish Foundation for Strategic Research , ID17-0114
Note

QC 20190923

Available from: 2019-09-09 Created: 2019-09-09 Last updated: 2019-10-22Bibliographically approved
Abrardo, A., Fodor, G., Moretti, M. & Telek, M. (2019). MMSE Receiver Design and SINR Calculation in MU-MIMO Systems With Imperfect CSI. IEEE Wireless Communications Letters, 8(1), 269-272
Open this publication in new window or tab >>MMSE Receiver Design and SINR Calculation in MU-MIMO Systems With Imperfect CSI
2019 (English)In: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 8, no 1, p. 269-272Article in journal (Refereed) Published
Abstract [en]

The performance of the uplink of multiuser multiple input multiple output systems depends critically on the receiver architecture and on the quality of the acquired channel state information. A popular approach is to design linear receivers that minimize the mean squared error (MSE) of the received data symbols. Unfortunately, most of the literature does not take into account the presence of channel state information errors in the MSE minimization. In this letter we develop a linear minimum MSE (MMSE) receiver that employs the noisy instantaneous channel estimates to minimize the MSE, and highlight the dependence of the receiver performance on the pilot-to-data power ratio. By invoking the theory of random matrices, we calculate the users' signal-to-interference-plus-noise ratio as a function of the number of antennas and the pilot-to-data power ratio of all users. Numerical results indicate that this new linear receiver outperforms the classical mismatched MMSE receiver.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Keywords
MIMO, channel state information, estimation error, mean square error methods
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-245929 (URN)10.1109/LWC.2018.2869763 (DOI)000459510200067 ()2-s2.0-85053318281 (Scopus ID)
Note

QC 20190312

Available from: 2019-03-12 Created: 2019-03-12 Last updated: 2019-03-12Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-2289-3159

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