Publications
240 results found
Nerini M, Clerckx B, 2023, Overhead-Free Blockage Detection and Precoding Through Physics-Based Graph Neural Networks: LIDAR Data Meets Ray Tracing, IEEE Wireless Communications Letters, Vol: 12, Pages: 565-569, ISSN: 2162-2337
In this letter, we address blockage detection and precoder design for multiple-input multiple-output (MIMO) links, without communication overhead required. Blockage detection is achieved by classifying light detection and ranging (LIDAR) data through a physics-based graph neural network (GNN). For precoder design, a preliminary channel estimate is obtained by running ray tracing on a 3D surface obtained from LIDAR data. This estimate is successively refined and the precoder is designed accordingly. Numerical simulations show that blockage detection is successful with 95% accuracy. Our digital precoding achieves 90% of the capacity and analog precoding outperforms previous works exploiting LIDAR for precoder design.
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
With the development of wireless communications, the technology of industrial Internet of Things (IIoT) has been considered as a candidate for the next generation of mobile communications, which could provide automatic services for the smart factory. Massive low-power devices are swarming into the scenario for providing network intelligence. These energy-thirsty devices all require efficient control state delivery. In this letter, an energy harvesting modulation (EHM) scheme is proposed for integrated control state and energy transfer (ICSET) towards these low-power devices. The performance of wireless energy transfer (WET) and wireless control state transfer (WCST) are also analysed theoretically. The ICSET performance is optimized by ensuring the control reliability. Simulation results validate the theoretical analysis. They also demonstrate that an appropriate time slot number within a period should be selected to increase the effective control rate, while ensuring the energy harvesting performance and the control reliability of IIoT.
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
In this letter, we investigate the performance of Rate-Splitting Multiple Access (RSMA) for an uplink communication system with finite blocklegnth (FBL). Considering a two-user Single-Input Single-Output (SISO) Multiple Access Channel (MAC), we study the impact of blocklength and target rate on the throughput and error probability performance of RSMA where one user message is split. We demonstrate that RSMA can outperform Non-Orthogonal Multiple Access (NOMA) in terms of throughput and error probability performance.
Cui H, Zhu L, Xiao Z, et al., 2023, Energy-Efficient RSMA for Multigroup Multicast and Multibeam Satellite Communications, IEEE Wireless Communications Letters, ISSN: 2162-2337
This letter studies energy-efficient rate-splitting multiple access (RSMA) for multigroup multicast and multibeam satellite communication systems. Specifically, we minimize the unmet system capacity, which means the rate difference between the requested user rate and the effective achieved rate, and communication energy consumption by optimizing the power allocation and rate allocation under the per-feed power and sum radiated power constraints. To solve the non-convex optimization problem, auxiliary variables and epigraph method are introduced to transform the original problem into a difference of convex functions programming. Then, the successive convex approximation (SCA) technique is used to obtain a suboptimal solution. Numerical results verify the superiority of our proposed solution compared to the benchmark methods.
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
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.
Singh SK, Agrawal K, Singh K, et al., 2023, RSMA for Hybrid RIS-UAV-aided Full-Duplex Communications with Finite Blocklength Codes under Imperfect SIC, IEEE Transactions on Wireless Communications, ISSN: 1536-1276
In this work, we consider a hybrid aerial full-duplex (FD) relaying consisting of a reconfigurable intelligent surface (RIS) mounted over an FD unmanned aerial vehicle (UAV) relay operating in decode and forward mode to assist the information transfer between the base station and multiple users. For better spectral efficiency, we investigate the use of rate splitting multiple access (RSMA) in such networks and focus on joint optimization of RSMA parameters, 3D-coordinates of the UAV/RIS, and phase shift matrix at the RIS along with analyzing the outage probability, block error rate (BLER) and achievable weighted sum rate for finite blocklength (FBL) and infinite blocklength (IBL) codes under imperfect successive interference cancellation (SIC) at each user and residual-self interference (RSI) at the UAV. We first formulate the weighted sum rate maximization problem and adopt the block coordinate descent (BCD) method to deal with the non-convex nature of the problem. Thereafter, we propose a BCD-based algorithm that jointly optimizes these parameters using a heuristic approach for optimum power allocation, a Riemannian conjugate gradient-based algorithm to get the optimal phase shift at the RIS, and an iterative algorithm to obtain the optimal UAV/RIS position. It also distributes the common rate among the users optimally. Next, with obtained optimal parameters, we further analyze the performance of the network and derive the closed-form expressions of BLER, outage probability, and average weighted sum rate. We present Monte Carlo simulation-based results to validate the accuracy of the proposed algorithms and derived expressions, and demonstrate the superiority of RSMA over non-orthogonal multiple access (NOMA) and conventional orthogonal multiple access (OMA) schemes.
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.
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
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
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: 1
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
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
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
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: 2
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: 8
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
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: 3
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: 2
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: 3
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: 8
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
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- Citations: 10
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.
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
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 survey of
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
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: 1
Clerckx B, Kim J, Choi KW, et al., 2022, Foundations of Wireless Information and Power Transfer: Theory, Prototypes, and Experiments, PROCEEDINGS OF THE IEEE, Vol: 110, Pages: 8-30, ISSN: 0018-9219
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- Citations: 7
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: 2
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