Publications
283 results found
Abanto-Leon LF, Hollick M, Clerckx B, et al., 2022, Sequential Parametric Optimization for Rate-Splitting Precoding in Non-Orthogonal Unicast and Multicast Transmissions, IEEE International Conference on Communications (ICC), Publisher: IEEE, Pages: 3904-3910, ISSN: 1550-3607
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- Citations: 1
Salem A, Masouros C, Clerckx B, 2022, Security Tradeoffs in Rate Splitting Multiple Access: Optimal Signal Splitting vs Revealing, IEEE International Conference on Communications (ICC), Publisher: IEEE, Pages: 592-597, ISSN: 2164-7038
Dizdar O, Clerckx B, 2022, Rate-Splitting Multiple Access for Communications and Jamming in Multi-Antenna Multi-Carrier Cognitive Radio Systems, IEEE TRANSACTIONS ON INFORMATION FORENSICS AND SECURITY, Vol: 17, Pages: 628-643, ISSN: 1556-6013
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- Citations: 9
Mao Y, Dizdar O, Clerckx B, et al., 2022, Rate-splitting multiple access: fundamentals, survey, and future research trends, IEEE Communications Surveys and Tutorials, Vol: 24, Pages: 2073-2126, ISSN: 1553-877X
Rate-splitting multiple access (RSMA) has emerged as a novel, general, and powerful framework for the design and optimization of non-orthogonal transmission, multiple access (MA), and interference management strategies for future wireless networks. By exploiting splitting of user messages as well as non-orthogonal transmission of common messages decoded by multiple users and private messages decoded by their corresponding users, RSMA can softly bridge and therefore reconcile the two extreme interference management strategies of fully decoding interference and treating interference as noise. RSMA has been shown to generalize and subsume as special cases four existing MA schemes, namely, orthogonal multiple access (OMA), physical-layer multicasting, space division multiple access (SDMA) based on linear precoding (currently used in the fifth generation wireless network–5G), and non-orthogonal multiple access (NOMA) based on linearly precoded superposition coding with successive interference cancellation (SIC). Through information and communication theoretic analysis, RSMA has been shown to be optimal (from a Degrees-of-Freedom region perspective) in several transmission scenarios. Compared to the conventional MA strategies used in 5G, RSMA enables spectral efficiency (SE), energy efficiency (EE), coverage, user fairness, reliability, and quality of service (QoS) enhancements for a wide range of network loads (including both underloaded and overloaded regimes) and user channel conditions. Furthermore, it enjoys a higher robustness against imperfect channel state information at the transmitter (CSIT) and entails lower feedback overhead and complexity. Despite its great potential to fundamentally change the physical (PHY) layer and media access control (MAC) layer of wireless communication networks, RSMA is still confronted with many challenges on the road towards standardization. In this paper, we present the first comprehensive tutorial on RSMA by providing a surv
Zhang Y, Clerckx B, 2022, WAVEFORM OPTIMIZATION FOR WIRELESS POWER TRANSFER WITH POWER AMPLIFIER AND ENERGY HARVESTER NON-LINEARITIES, 47th IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Publisher: IEEE, Pages: 8632-8636, ISSN: 1520-6149
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- Citations: 1
Yin L, Clerckx B, 2022, Rate-Splitting Multiple Access for Dual-Functional Radar-Communication Satellite Systems, IEEE Wireless Communications and Networking Conference (IEEE WCNC), Publisher: IEEE, Pages: 1-6, ISSN: 1525-3511
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- Citations: 5
Kim J, Clerckx B, 2021, Wireless Information and Power Transfer for IoT: Pulse Position Modulation, Integrated Receiver, and Experimental Validation, IEEE INTERNET OF THINGS JOURNAL, Vol: 9, Pages: 12378-12394, ISSN: 2327-4662
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- Citations: 6
Xu C, Clerckx B, Chen S, et al., 2021, Rate-Splitting Multiple Access for Multi-Antenna Joint Radar and Communications, IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING, Vol: 15, Pages: 1332-1347, ISSN: 1932-4553
Dizdar O, Mao Y, Clerckx B, 2021, Rate-splitting multiple access to mitigate the curse of mobility in (massive) MIMO networks, IEEE Transactions on Wireless Communications, Vol: 69, Pages: 6765-6780, ISSN: 1536-1276
Rate-Splitting Multiple Access (RSMA) is a robust multiple access scheme for downlink multi-antenna wireless networks. RSMA relies on multi-antenna Rate-Splitting (RS) at the transmitter and Successive Interference Cancellation (SIC) at the receivers. In this work, we study the performance of RSMA under the important setup of imperfect Channel State Information at the Transmitter (CSIT) originating from user mobility and latency/delay (between CSI acquisition and data transmission) in the network. We derive a lower bound on the ergodic sum-rate of RSMA for an arbitrary number of transmit antennas, number of users, user speed and transmit power. Then, we study the power allocation between common and private streams and obtain a closed-form solution for optimal power allocation that maximizes the obtained lower bound. The proposed power allocation greatly reduces precoder design complexity for RSMA. By Link-Level Simulations (LLS), we demonstrate that RSMA with the proposed power allocation is robust to the degrading effects of user mobility and has significantly higher performance compared to conventional multi-user (massive) Multiple-Input Multiple-Output (MIMO) strategies. The work has important practical significance as results demonstrate that, in contrast to conventional multi-user (massive) MIMO whose performance collapse under mobility, RSMA can maintain reliable multi-user connectivity in mobile deployments.
Reifert R-J, Ahmad AA, Mao Y, et al., 2021, Rate-Splitting Multiple Access in Cache-Aided Cloud-Radio Access Networks, FRONTIERS IN COMMUNICATIONS AND NETWORKS, Vol: 2
Bansal A, Singh K, Clerckx B, et al., 2021, Rate-Splitting Multiple Access for Intelligent Reflecting Surface Aided Multi-User Communications, IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, Vol: 70, Pages: 9217-9229, ISSN: 0018-9545
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- Citations: 42
Ahmad AA, Mao Y, Sezgin A, et al., 2021, Rate Splitting Multiple Access in C-RAN: A Scalable and Robust Design, IEEE TRANSACTIONS ON COMMUNICATIONS, Vol: 69, Pages: 5727-5743, ISSN: 0090-6778
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- Citations: 24
Shen S, Clerckx B, 2021, Joint waveform and beamforming optimization for MIMO wireless power transfer, IEEE Transactions on Wireless Communications, Vol: 69, Pages: 5441-5455, ISSN: 1536-1276
In this paper, we study a multi-sine multiple-input multiple-output (MIMO) wireless power transfer (WPT) system with the objective to increase the output DC power. We jointly optimize the multi-sine waveform and beamforming accounting for the rectenna nonlinearity, and consider two combining schemes for the rectennas at the receiver, namely DC and RF combinings. For DC combining, the waveform and transmit beamforming are optimized, as a function of the channel state information (CSI). For RF combining, the optimal transmit and receive beamformings are provided in closed form and the waveform is optimized. We also consider a practical RF combining circuit using phase shifter and RF power combiner and optimize the waveform, transmit beamforming, and analog receive beamforming adaptive to the CSI. Two types of performance evaluations, based on the nonlinear rectenna model and accurate and realistic circuit simulations, are provided. The evaluations demonstrate that the joint waveform and beamforming design can increase the output DC power by leveraging the beamforming gain, the frequency diversity gain, and the rectenna nonlinearity. It also shows that the joint waveform and beamforming design provides a higher output DC power than the beamforming-only design with a relative gain of 180% in a two-transmit antenna sixteen-sinewave two-receive antenna setup.
Clerckx B, Huang K, Varshney LR, et al., 2021, Wireless power transfer for future networks: signal processing, machine learning, computing, and sensing, IEEE Journal of Selected Topics in Signal Processing, Vol: 15, Pages: 1060-1094, ISSN: 1932-4553
Wireless power transfer (WPT) is an emerging paradigm that will enable using wireless to its full potential in future networks, not only to convey information but also to deliver energy. Such networks will enable trillions of future low-power devices to sense, compute, connect, and energize anywhere, anytime, and on the move. The design of such future networks brings new challenges and opportunities for signal processing, machine learning, sensing, and computing. The objective is to make the best use of the RF radiations, spectrum, and network infrastructure to provide cost-effective and real-time power supplies to wireless devices and enable wireless-powered applications. In this paper, we first review recent signal processing techniques to make WPT and wireless information and power transfer (WIPT) as efficient as possible. Topics include high-power amplifier and energy harvester nonlinearities, active and passive beamforming, intelligent reflecting surfaces, receive combining with multi-antenna harvester, modulation, coding, waveform, large-scale (massive) multiple-input multiple-output (MIMO), channel acquisition, transmit diversity, multi-user power region characterization, coordinated multipoint, and distributed antenna systems. Then, we overview two different design methodologies: the model and optimize approach relying on analytical system models, modern convex optimization, and communication/information theory, and the learning approach based on data-driven end-to-end learning and physics-based learning. We discuss the pros and cons of each approach, especially when accounting for various nonlinearities in wireless-powered networks, and identify interesting emerging opportunities for the approaches to complement each other. Finally, we identify new emerging wireless technologies where WPT may play a key role—wireless-powered mobile edge computing, wireless-powered sensing, and wireless-powered federated learning—arguing WPT, communication, compu
Clerckx B, Huang K, Varshney L, et al., 2021, Guest Editoral Signal Processing Advances in Wireless Transmission of Information and Power, IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING, Vol: 15, Pages: 1056-1059, ISSN: 1932-4553
Mao Y, Piovano E, Clerckx B, 2021, Rate-splitting multiple access for overloaded cellular internet of things, IEEE Transactions on Wireless Communications, Vol: 69, Pages: 4504-4519, ISSN: 1536-1276
In the near future, it is envisioned that cellular networks will have to cope with extensive internet of things (IoT) devices. Therefore, a required feature of cellular IoT will be the capability to serve simultaneously a large number of devices with heterogeneous demands and qualities of channel state information at the transmitter (CSIT). In this paper, we focus on an overloaded multiple-input single-output (MISO) broadcast channel (BC) with two groups of CSIT qualities, namely, one group of users (representative of high-end devices) for which the transmitter has partial knowledge of the CSI, the other group of users (representative of IoT devices) for which the transmitter only has knowledge of the statistical CSI (i.e., the distribution information of the user channels). We introduce rate-splitting multiple access (RSMA), a new multiple access based on multi-antenna rate-splitting (RS) technique for cellular IoT. Two strategies are proposed, namely, time partitioning-RSMA (TP-RSMA) and power partitioning-RSMA (PP-RSMA). The former independently serves the two groups of users over orthogonal time slots while the latter jointly serves the two groups of users within the same time slot in a non-orthogonal manner. We first show at high signal-to-noise ratio (SNR) that PP-RSMA achieves the optimal degrees-of-freedom (DoF) in an overloaded MISO BC with heterogeneous CSIT qualities. We then show at finite SNR that PP-RSMA achieves explicit sum rate gain over TP-RSMA and all baseline schemes by marrying the benefits of PP and RSMA. Furthermore, PP-RSMA is robust to CSIT inaccuracy and flexible to cope with quality of service (QoS) rate constraints of all users. The DoF and rate analysis helps us in drawing the conclusion that PP-RSMA is a powerful framework for cellular IoT with a large number of devices.
Clerckx B, Mao Y, Schober R, et al., 2021, Is NOMA efficient in multi-antenna networks? A critical look at next generation multiple access techniques, IEEE Open Journal of the Communications Society, Vol: 2, Pages: 1310-1343, ISSN: 2644-125X
In the past few years, a large body of literature has been created on downlink Non-Orthogonal Multiple Access (NOMA),employing superposition coding and Successive Interference Cancellation (SIC), in multi-antenna wireless networks. Furthermore, the benefits of NOMA over Orthogonal Multiple Access (OMA) have been highlighted. In this paper, we take a critical and fresh look at the downlink Next Generation Multiple Access (NGMA) literature. Instead of contrasting NOMA with OMA, we contrast NOMA with two other multiple access baselines. The first is conventional Multi-User Linear Precoding (MU–LP), as used in Space-Division Multiple Access (SDMA) and multi-user Multiple-Input Multiple-Output (MIMO) in 4G and 5G. The second, called Rate-Splitting Multiple Access (RSMA), is based on multi-antenna Rate-Splitting (RS). It is also a non-orthogonal transmission strategy relying on SIC developed in the past few years in parallel and independently from NOMA. We show that there is some confusion about the benefits of NOMA, and we dispel the associated misconceptions. First, we highlight why NOMA is inefficient in multi-antenna settings based on basic multiplexing gain analysis. We stress that the issue lies in how the NOMA literature, originally developed for single-antenna setups, has been hastily applied to multi-antenna setups, resulting in a misuse of spatial dimensions and therefore loss in multiplexing gains and rate. Second, we show that NOMA incurs a severe multiplexing gain loss despite an increased receiver complexity due to an inefficient use of SIC receivers. Third, we emphasize that much of the merits of NOMA are due to the constant comparison to OMA instead of comparing it to MU–LP and RS baselines. We then expose the pivotal design constraint that multi-antenna NOMA requires one user to fully decode the
Kim J, Clerckx B, 2021, Range expansion for wireless power transfer using joint beamforming and waveform architecture: an experimental study in indoor environment, IEEE Wireless Communications Letters, Vol: 10, Pages: 1237-1241, ISSN: 2162-2337
Far-field Wireless Power Transfer (WPT) has emerged as a potential power source for the Internet of Things (IoT) and Wireless Sensor Network (WSN). The expansion of the power transfer range is one of the key challenges to make the technology viable. In this letter, we experimentally study a channel-adaptive joint beamforming and waveform architecture to expand the power transfer range. WPT experiments have been conducted in a variety of wireless channels at various distances in a realistic indoor environment. The measurement data have been fitted using a simple analytical model to analyze the output DC power and achievable range improvement depending on the signal design schemes and the number of tones and antennas. The model shows a clear relationship between signal design versus output DC power and achievable range, and highlight the significant benefit of the proposed architecture to expand the power transfer range.
Flores AR, De Lamare RC, Clerckx B, 2021, Tomlinson-Harashima Precoded Rate-Splitting With Stream Combiners for MU-MIMO Systems, IEEE TRANSACTIONS ON COMMUNICATIONS, Vol: 69, Pages: 3833-3845, ISSN: 0090-6778
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- Citations: 9
Yin L, Clerckx B, 2021, Rate-Splitting Multiple Access for Multigroup Multicast and Multibeam Satellite Systems, IEEE TRANSACTIONS ON COMMUNICATIONS, Vol: 69, Pages: 976-990, ISSN: 0090-6778
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- Citations: 42
Shen S, Clerckx B, 2021, Beamforming Optimization for MIMO Wireless Power Transfer With Nonlinear Energy Harvesting: RF Combining Versus DC Combining, IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, Vol: 20, Pages: 199-213, ISSN: 1536-1276
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- Citations: 26
Dizdar O, Clerckx B, 2021, Rate Splitting Multiple Access for Multi-Antenna Multi-Carrier Joint Communications and Jamming, 10th Conference of the Sensor-Signal-Processing-for-Defence (SSPD), Publisher: IEEE, Pages: 70-74
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- Citations: 1
Dizdar O, Kaushik A, Clerckx B, et al., 2021, Rate-Splitting Multiple Access for Joint Radar-Communications with Low-Resolution DACs, IEEE International Conference on Communications (ICC), Publisher: IEEE, ISSN: 2164-7038
Yin L, Dizdar O, Clerckx B, 2021, Rate-Splitting Multiple Access for Multigroup Multicast Cellular and Satellite Communications: PHY Layer Design and Link-Level Simulations, IEEE International Conference on Communications (ICC), Publisher: IEEE, ISSN: 2164-7038
Matthiesen B, Mao Y, Popovski P, et al., 2021, GLOBALLY OPTIMAL BEAMFORMING FOR RATE SPLITTING MULTIPLE ACCESS, IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Publisher: IEEE, Pages: 4775-4779
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- Citations: 10
Salem A, Masouros C, Clerckx B, 2021, Rate Splitting With Finite Constellations: The Benefits of Interference Exploitation vs Suppression, IEEE OPEN JOURNAL OF THE COMMUNICATIONS SOCIETY, Vol: 2, Pages: 1541-1557
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- Citations: 5
Yin L, Clerckx B, Mao Y, 2021, Rate-Splitting Multiple Access for Multi-Antenna Broadcast Channels with Statistical CSIT, IEEE Wireless Communications and Networking Conference (WCNC), Publisher: IEEE, ISSN: 2167-8189
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- Citations: 10
Kim J, Clerckx B, Mitcheson PD, 2020, Signal and system design for wireless power transfer: prototype, experiment and validation, IEEE Transactions on Wireless Communications, Vol: 19, Pages: 7453-7469, ISSN: 1536-1276
A new line of research on communications and signals design for Wireless Power Transfer (WPT) has recently emerged in the communication literature. Promising signal strategies to maximize the power transfer efficiency of WPT rely on (energy) beamforming, waveform, modulation and transmit diversity, and a combination thereof. To a great extent, the study of those strategies has so far been limited to theoretical performance analysis. In this paper, we study the real over-the-air performance of all the aforementioned signal strategies for WPT. To that end, we have designed, prototyped and experimented an innovative radiative WPT architecture based on Software-Defined Radio (SDR) that can operate in open-loop and closed-loop (with channel acquisition at the transmitter) modes. The prototype consists of three important blocks, namely the channel estimator, the signal generator, and the energy harvester. The experiments have been conducted in a variety of deployments, including frequency flat and frequency selective channels, under static and mobility conditions. Experiments highlight that a channel-adaptive WPT architecture based on joint beamforming and waveform design offers significant performance improvements in harvested DC power over conventional single-antenna/multi-antenna continuous wave systems. The experimental results fully validate the observations predicted from the theoretical signal designs and confirm the crucial and beneficial role played by the energy harvester nonlinearity.
Mao Y, Clerckx B, 2020, Beyond Dirty Paper Coding for Multi-Antenna Broadcast Channel With Partial CSIT: A Rate-Splitting Approach, IEEE TRANSACTIONS ON COMMUNICATIONS, Vol: 68, Pages: 6775-6791, ISSN: 0090-6778
Joudeh H, Yi X, Clerckx B, et al., 2020, On the Optimality of Treating Inter-Cell Interference as Noise: Downlink Cellular Networks and Uplink-Downlink Duality, IEEE TRANSACTIONS ON INFORMATION THEORY, Vol: 66, Pages: 6939-6961, ISSN: 0018-9448
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- Citations: 7
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