Publications
283 results found
Xu J, Dizdar O, Clerckx B, 2023, Rate-Splitting Multiple Access for Short-Packet Uplink Communications: A Finite Blocklength Analysis, IEEE COMMUNICATIONS LETTERS, Vol: 27, Pages: 517-521, ISSN: 1089-7798
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- Citations: 1
Zhao Y, Wu Y, Hu J, et al., 2023, Energy Harvesting Modulation for Integrated Control State and Energy Transfer in Industrial IoT, IEEE WIRELESS COMMUNICATIONS LETTERS, Vol: 12, Pages: 292-296, ISSN: 2162-2337
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- Citations: 1
Yin L, Clerckx B, 2023, Rate-Splitting Multiple Access for Satellite-Terrestrial Integrated Networks: Benefits of Coordination and Cooperation, IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, Vol: 22, Pages: 317-332, ISSN: 1536-1276
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- Citations: 4
Park J, Lee B, Choi J, et al., 2023, Rate-Splitting Multiple Access for 6G Networks: Ten Promising Scenarios and Applications, IEEE Network, ISSN: 0890-8044
In the upcoming 6G era, multiple access (MA) will play an essential role in achieving high throughput performances required in a wide range of wireless applications. Since MA and interference management are closely related issues, the conventional MA techniques are limited in that they cannot provide near-optimal performance in universal interference regimes. Recently, rate-splitting multiple access (RSMA) has been gaining much attention. RSMA splits an individual message into two parts: a common part, decodable by every user, and a private part, decodable only by the intended user. Each user first decodes the common message and then decodes its private message by applying successive interference cancellation (SIC). By doing so, RSMA not only embraces the existing MA techniques as special cases but also provides significant performance gains by efficiently mitigating inter-user interference in a broad range of interference regimes. In this article, we first present the theoretical foundation of RSMA. Subsequently, we put forth four key benefits of RSMA: spectral efficiency, robustness, scalability, and flexibility. Upon this, we describe how RSMA can enable ten promising scenarios and applications along with future research directions to pave the way for 6G.
Shen S, Kim J, Clerckx B, 2023, Closed-loop wireless power transfer with adaptive waveform and beamforming: design, prototype, and experiment, IEEE Journal of Microwaves, Vol: 3, Pages: 29-42, ISSN: 2692-8388
A closed-loop far-field wireless power transfer (WPT) system with adaptive waveform and beamforming using limited feedback is designed, prototyped, and experimented. Spatial domain and frequency domain are jointly exploited by utilizing waveform and beamforming at the transmitter in WPT system to adapt to the multipath fading channel and boost the output dc power. A closed-loop architecture based on a codebook design and an over-the-air limited feedback with low complexity is proposed. The codebook consists of multiple codewords where each codeword represents particular waveform and beamforming. The transmitter sweeps through the codebook and the receiver then feeds the optimal codeword index back to the transmitter, so that the waveform and beamforming can be adaptive for maximizing the output dc power without requiring explicit channel estimation and the knowledge of accurate Channel State Information. The proposed closed-loop WPT with adaptive waveform and beamforming using limited feedback is prototyped using a Software Defined Radio equipment and measured in two real indoor environments. It is experimentally shown that the proposed closed-loop WPT with adaptive waveform and beamforming is able to enhance the output dc power by up to 14.7 dB in comparison with conventional 1-tone 1-antenna WPT system.
Tian C, Mao Y, Zhao K, et al., 2023, Reconfigurable Intelligent Surface Empowered Rate-Splitting Multiple Access for Simultaneous Wireless Information and Power Transfer, IEEE Wireless Communications and Networking Conference (WCNC), Publisher: IEEE, ISSN: 1525-3511
Zhang Y, Clerckx B, 2023, Waveform Design for Wireless Power Transfer With Power Amplifier and Energy Harvester Non-Linearities, IEEE TRANSACTIONS ON SIGNAL PROCESSING, Vol: 71, Pages: 2638-2653, ISSN: 1053-587X
Aditya S, Dizdar O, Clerckx B, et al., 2022, Sensing using Coded Communications Signals, IEEE Open Journal of the Communications Society, Vol: 4, Pages: 134-152, ISSN: 2644-125X
A key challenge for common waveforms for Integrated Sensing and Communications – widely regarded as a resource-efficient way to achieve high performance for both functionalities – lies in leveraging information-bearing channel-coded communications signal(s) (c.c.s) for sensing. In this paper, we investigate the range-Doppler sensing performance of c.c.s in multi-user interference-limited scenarios, and show that it is affected by sidelobes whose form depends on whether the c.c.s modulates a single-carrier or OFDM waveform. While uncoded signals give rise to asymptotically zero sidelobes due to the law of large numbers, it is not obvious that the same holds for c.c.s, as structured codes (e.g., linear block codes) induce dependence across codeword symbols. In this paper, we show that c.c.s also give rise to asymptotically zero sidelobes – for both single-carrier and OFDM waveforms – by deriving upper bounds for the tail probabilities of the sidelobe magnitudes that decay as exp(−O(code rate×block length)) . Consequently, for any code rate, c.c.s are effective sensing signals that are robust to multi-user interference at sufficiently large block lengths, with negligible difference in performance based on whether they modulate a single-carrier or OFDM waveform. We verify the latter implication through simulations, where we observe the sensing performance (i.e., the detection and false-alarm probabilities) of a QPSK-modulated c.c.s (code rate = 120/1024, block length = 1024 symbols) to match that of a comparable interference-free FMCW waveform even at high interference levels (SIR of −11dB), for both single-carrier and OFDM waveforms.
Katwe M, Singh K, Clerckx B, et al., 2022, Rate-Splitting Multiple Access and Dynamic User Clustering for Sum-Rate Maximization in Multiple RISs-Aided Uplink mmWave System, IEEE TRANSACTIONS ON COMMUNICATIONS, Vol: 70, Pages: 7365-7383, ISSN: 0090-6778
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- Citations: 7
Xu Y, Mao Y, Dizdar O, et al., 2022, Rate-Splitting Multiple Access With Finite Blocklength for Short-Packet and Low-Latency Downlink Communications, IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, Vol: 71, Pages: 12333-12337, ISSN: 0018-9545
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- Citations: 9
Bastami H, Moradikia M, Abdelhadi A, et al., 2022, Maximizing the Secrecy Energy Efficiency of the Cooperative Rate-Splitting Aided Downlink in Multi-Carrier UAV Networks, IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, Vol: 71, Pages: 11803-11819, ISSN: 0018-9545
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- Citations: 4
Xiao Z, Han Z, Nallanathan A, et al., 2022, Antenna Array Enabled Space/Air/Ground Communications and Networking for 6G, IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, Vol: 40, Pages: 2773-2804, ISSN: 0733-8716
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- Citations: 17
Li H, Mao Y, Dizdar O, et al., 2022, Rate-Splitting Multiple Access for 6G-Part III: Interplay With Reconfigurable Intelligent Surfaces, IEEE COMMUNICATIONS LETTERS, Vol: 26, Pages: 2242-2246, ISSN: 1089-7798
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- Citations: 6
Xiao Z, Han Z, Nallanathan A, et al., 2022, Guest Editorial Special Issue on Antenna Array Enabled Space/Air/Ground Communications and Networking, IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, Vol: 40, Pages: 2767-2772, ISSN: 0733-8716
Mishra A, Mao Y, Dizdar O, et al., 2022, Rate-Splitting Multiple Access for 6G-Part I: Principles, Applications and Future Works, IEEE COMMUNICATIONS LETTERS, Vol: 26, Pages: 2232-2236, ISSN: 1089-7798
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- Citations: 8
Yin L, Mao Y, Dizdar O, et al., 2022, Rate-Splitting Multiple Access for 6G-Part II: Interplay With Integrated Sensing and Communications, IEEE COMMUNICATIONS LETTERS, Vol: 26, Pages: 2237-2241, ISSN: 1089-7798
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- Citations: 1
Feng Z, Clerckx B, Zhao Y, 2022, Waveform and beamforming design for intelligent reflecting surface aided wireless power transfer: single-user and multi-user solutions, IEEE Transactions on Wireless Communications, Vol: 21, Pages: 5346-5361, ISSN: 1536-1276
In this paper, we study the waveform and passive beamforming design for intelligent reflecting surface (IRS)-aided wireless power transfer (WPT). Generalized multi-user and low complexity single-user algorithms are demonstrated based on alternating optimization (AO) framework to maximize the weighted sum output direct current (DC), subject to the transmit power constraints and passive beamforming modulus constraints. The input signal waveform and IRS passive beamforming phase shifts are jointly designed as a function of users’ individual frequency-selective channel state information (CSI). The energy harvester nonlinearity is explored and two IRS deployment schemes, namely frequency selective IRS (FS-IRS) and frequency flat IRS (FF-IRS), are modeled and analyzed. This paper highlights the fact that IRS can provide an extra passive beamforming gain on output DC power over conventional WPT designs and significantly influence the waveform design by leveraging the benefit of passive beamforming, frequency diversity and energy harvester nonlinearity. Even though FF-IRS exhibits lower output DC than the ideal FS-IRS, it still achieves substantially increased DC power over conventional WPT designs. Performance evaluations confirm the significant benefits of a joint waveform and passive beamforming design accounting for the energy harvester nonlinearity to boost the performance of single-user and multi-user WPT systems.
Zhou G, Mao Y, Clerckx B, 2022, Rate-Splitting Multiple Access for Multi-Antenna Downlink Communication Systems: Spectral and Energy Efficiency Tradeoff, IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, Vol: 21, Pages: 4816-4828, ISSN: 1536-1276
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- Citations: 22
Dizdar O, Kaushik A, Clerckx B, et al., 2022, Energy efficient dual-functional radar-communication: rate-splitting multiple access, low-resolution DACs, and RF chain selection, IEEE Open Journal of the Communications Society, Vol: 3, ISSN: 2644-125X
Dual-Functional Radar-Communication systems enhance the benefits of communications and radar sensing by jointly implementing these on the same hardware platform and using the common RF resources. An important and latest concern to be addressed in designing such Dual-Functional Radar-Communication systems is maximizing the energy-efficiency. In this paper, we consider a Dual-Functional Radar-Communication system performing simultaneous multi-user communications and radar sensing, and investigate the energy-efficiency behaviour with respect to active transmission elements. Specifically, we formulate a problem to find the optimal precoders and the number of active RF chains for maximum energy-efficiency by taking into consideration the power consumption of low-resolution Digital-to-Analog Converters on each RF chain under communications and radar performance constraints. We consider Rate-Splitting Multiple Access to perform multi-user communications with perfect and imperfect Channel State Information at Transmitter. The formulated non-convex optimization problem is solved by means of a novel algorithm. We demonstrate by numerical results that Rate Splitting Multiple Access achieves an improved energy-efficiency by employing a smaller number of RF chains compared to Space Division Multiple Access, owing to its generalized structure and improved interference management capabilities.
Li Q, El-Hajjar M, Hemadeh I, et al., 2022, Reconfigurable Intelligent Surfaces Relying on Non-Diagonal Phase Shift Matrices, IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, Vol: 71, Pages: 6367-6383, ISSN: 0018-9545
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- Citations: 10
Mishra A, Mao Y, Sanguinetti L, et al., 2022, Rate-Splitting Assisted Massive Machine-Type Communications in Cell-Free Massive MIMO, IEEE COMMUNICATIONS LETTERS, Vol: 26, Pages: 1358-1362, ISSN: 1089-7798
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- Citations: 12
Si ZW, Yin L, Clerckx B, 2022, Rate-Splitting Multiple Access for Multigateway Multibeam Satellite Systems With Feeder Link Interference, IEEE TRANSACTIONS ON COMMUNICATIONS, Vol: 70, Pages: 2147-2162, ISSN: 0090-6778
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- Citations: 12
Lopez OLA, Clerckx B, Latva-Aho M, 2022, Dynamic RF Combining for Multi-Antenna Ambient Energy Harvesting, IEEE WIRELESS COMMUNICATIONS LETTERS, Vol: 11, Pages: 493-497, ISSN: 2162-2337
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- Citations: 4
Shen S, Clerckx B, Murch R, 2022, Modeling and architecture design of reconfigurable intelligent surfaces using scattering parameter network analysis, IEEE Transactions on Wireless Communications, Vol: 21, Pages: 1229-1243, ISSN: 1536-1276
Reconfigurable intelligent surfaces (RISs) are an emerging technology for future wireless communication. The vast majority of recent research on RIS has focused on system level optimizations. However, developing straightforward and tractable electromagnetic models that are suitable for RIS aided communication modeling remains an open issue. In this paper, we address this issue and derive communication models by using rigorous scattering parameter network analysis. We also propose new RIS architectures based on group and fully connected reconfigurable impedance networks that can adjust not only the phases but also the magnitudes of the impinging waves, which are more general and more efficient than conventional single connected reconfigurable impedance network that only adjusts the phases of the impinging waves. In addition, the scaling law of the received signal power of an RIS aided system with reconfigurable impedance networks is also derived. Compared with the single connected reconfigurable impedance network, our group and fully connected reconfigurable impedance network can increase the received signal power by up to 62%, or maintain the same received signal power with a number of RIS elements reduced by up to 21%. We also investigate the proposed architecture in deployments with distance-dependent pathloss and Rician fading channel, and show that the proposed group and fully connected reconfigurable impedance networks outperform the single connected case by up to 34% and 48%, respectively.
Zhao Y, Clerckx B, Feng Z, 2022, IRS-aided SWIPT: Joint waveform, active and passive beamforming design under nonlinear harvester model, IEEE Transactions on Wireless Communications, Vol: 70, Pages: 1345-1359, ISSN: 1536-1276
The performance of Simultaneous Wireless Information and Power Transfer (SWIPT) is mainly constrained by the received Radio-Frequency (RF) signal strength. To tackle this problem, we introduce an Intelligent Reflecting Surface (IRS) to compensate the propagation loss and boost the transmission efficiency. This paper proposes a novel IRS-aided SWIPT system where a multi-carrier multi-antenna Access Point (AP) transmits information and power simultaneously, with the assist of an IRS, to a single-antenna User Equipment (UE) employing practical receiving schemes. Considering harvester nonlinearity, we characterize the achievable Rate-Energy (R-E) region through a joint optimization of waveform, active and passive beamforming based on the Channel State Information at the Transmitter (CSIT). This problem is solved by the Block Coordinate Descent (BCD) method, where we obtain the active precoder in closed form, the passive beamforming by the Successive Convex Approximation (SCA) approach, and the waveform amplitude by the Geometric Programming (GP) technique. To facilitate practical implementation, we also propose a low-complexity design based on closed-form adaptive waveform schemes. Simulation results demonstrate the proposed algorithms bring considerable R-E gains with robustness to CSIT inaccuracy and finite IRS states, and emphasize the importance of modeling harvester nonlinearity in the IRS-aided SWIPT design.
Mishra A, Mao Y, Dizdar O, et al., 2022, Rate-Splitting Multiple Access for Downlink Multiuser MIMO: Precoder Optimization and PHY-Layer Design, IEEE TRANSACTIONS ON COMMUNICATIONS, Vol: 70, Pages: 874-890, ISSN: 0090-6778
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- Citations: 19
Clerckx B, Kim J, Choi KW, et al., 2022, Foundations of wireless information and power transfer: theory, prototypes, and experiments, Proceedings of the Institute of Electrical and Electronics Engineers (IEEE), Vol: 110, Pages: 8-30, ISSN: 0018-9219
As wireless has disrupted communications, wireless will also disrupt the delivery of energy. Future wireless networks will be equipped with (radiative) wireless power transfer (WPT) capability and exploit radio waves to carry both energy and information through unified wireless information and power transfer (WIPT). Such networks will make the best use of the RF spectrum and radiation, as well as the network infrastructure for the dual purpose of communicating and energizing. Consequently, those networks will enable trillions of future low-power devices to sense, compute, connect, and energize anywhere, anytime, and on the move. In this article, we review the foundations of such a future system. We first give an overview of the fundamental theoretical building blocks of WPT and WIPT. Then, we discuss some state-of-the-art experimental setups and prototypes of both WPT and WIPT, and contrast theoretical and experimental results. We draw special attention to how the integration of RF, signal, and system designs in WPT and WIPT leads to new theoretical and experimental design challenges for both microwave and communication engineers and highlight some promising solutions. Topics and experimental testbeds discussed include closed-loop WPT and WIPT architectures with beamforming, waveform, channel acquisition, and single-antenna/multiantenna energy harvester, centralized and distributed WPT, reconfigurable metasurfaces and intelligent surfaces for WPT, transmitter and receiver architecture for WIPT, modulation, and rate–energy tradeoff. Moreover, we highlight important theoretical and experimental research directions to be addressed for WPT and WIPT to become a foundational technology of future wireless networks.
Fang T, Mao Y, Shen S, et al., 2022, Fully Connected Reconfigurable Intelligent Surface Aided Rate-Splitting Multiple Access for Multi-User Multi-Antenna Transmission, IEEE International Conference on Communications (ICC), Publisher: IEEE, Pages: 675-680, ISSN: 2164-7038
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- Citations: 6
Matthiesen B, Mao Y, Dekorsy A, et al., 2022, Globally Optimal Spectrum- and Energy-Efficient Beamforming for Rate Splitting Multiple Access, IEEE TRANSACTIONS ON SIGNAL PROCESSING, Vol: 70, Pages: 5025-5040, ISSN: 1053-587X
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- Citations: 6
Wang S, Yang H, Clerckx B, 2022, Dynamic Air-Ground Collaboration for Multi-Access Edge Computing, IEEE International Conference on Communications (ICC), Publisher: IEEE, Pages: 5365-5371, ISSN: 1550-3607
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- Citations: 3
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