Signal Design and Optimization for Wireless Communication Systems Employing Nonlinear RF Energy Harvesting

• Applicant: Professor Dr.-Ing. Robert Schober
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 414988357

• Final Report Year: 2023

Final Report Abstract

In this project, we studied wireless communication networks based on RF WPT. First, since practical electrical circuits employed for EH exhibit a nonlinear behaviour, by carefully analyzing these circuits, we derived an exact and accurate EH model to characterize the dependency of the instantaneous harvested power on the instantaneous input power. We demonstrated that for WPT-based communication systems, the waveform of the transmit signal has to be carefully designed taking into account the nonlinearities of the EH circuits in both the low and high input-power regimes. Furthermore, we also showed that for small durations of the transmit signal pulses, EH circuits also have memory, and to characterize all nonlinear and memory effects of EH circuits, we proposed a model based on MDP and DNN. Next, we considered single-antenna SWIPT systems with collocated and separated IR and EH nodes, where the MDP state of the EH device may and may not be known at the IR node, respectively. We showed that the phase of the transmit symbols is uniformly distributed and statistically independent of the MDP state and the transmit symbol amplitudes, whose pdfs are obtained for both SWIPT system configurations as solutions of corresponding optimization problems. Then, we studied multi-user multi-antenna WPT systems and WPCNs and jointly determined the optimal transmit energy signals and resource allocation policies for these systems. In particular, we showed that for multi-user MIMO WPT, the optimal energy signal employs a scalar input symbol and at most two beamforming vectors, which were determined as solution of a non-convex optimization problem. Furthermore, for multi-user MISO WPCNs, we proved that the maximum number of transmit energy signal vectors exceeds the number of users by one and proposed an optimal and three suboptimal algorithms to find them. Our simulation results demonstrated that, at the expense of higher computational complexity, the proposed optimal and suboptimal schemes for multi-user WPT and WPCNs significantly outperform two baseline schemes based on linear and sigmoidal EH models, respectively. Despite the significant progress in the optimal design of communication systems based on WPT, there are still several implementation challenges that may limit the applicability of these networks and are to be tackled in future work. Nevertheless, we believe that the analytical and numerical results obtained in this project will be beneficial for the design of practical EH-based communications networks in the nearest future.

Publications

• Conditional Capacity and Transmit Signal Design for SWIPT Systems With Multiple Nonlinear Energy Harvesting Receivers. IEEE Transactions on Communications, 68(1), 582-601.
  Morsi, Rania; Jamali, Vahid; Hagelauer, Amelie; Ng, Derrick Wing Kwan & Schober, Robert
  
• Rate-Power Region of SWIPT Systems Employing Nonlinear Energy Harvester Circuits with Memory. ICC 2020 - 2020 IEEE International Conference on Communications (ICC), 1-7. IEEE.
  Shanin, Nikita; Cottatellucci, Laura & Schober, Robert
  
• Markov Decision Process Based Design of SWIPT Systems: Non-Linear EH Circuits, Memory, and Impedance Mismatch. IEEE Transactions on Communications, 69(2), 1259-1274.
  Shanin, Nikita; Cottatellucci, Laura & Schober, Robert
  
• Optimal Transmit Strategy for MIMO WPT Systems With Non-linear Energy Harvesting. 2021 17th International Conference on Distributed Computing in Sensor Systems (DCOSS), 520-527. IEEE.
  Shanin, Nikita; Cottatellucci, Laura & Schober, Robert
  
• Distributed Multiantenna Frequency-Selective Energy Beamforming With Joint Total and Individual Power Constraints. IEEE Transactions on Green Communications and Networking, 6(4), 2100-2114.
  Luo, Bing; Yeoh, Phee Lep; Schober, Robert & Krongold, Brian S.
  
• Optimal Energy Signal Design for Multi-user MISO WPCNs With Non-linear Energy Harvesting Circuits
  N. Shanin, A. Hagelauer, L. Cottatellucci & R. Schober
  
• Optimal Resource Allocation and Beamforming for Two-User Miso WPCNS for a Non-Linear Circuit-Based EH Model : (Invited Paper). ICASSP 2022 - 2022 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 8642-8646. IEEE.
  Shanin, Nikita; Garkisch, Moritz; Hagelauer, Amelie; Schober, Robert & Cottatellucci, Laura
  
• Optimal Resource Allocation Design for Large IRS-Assisted SWIPT Systems: A Scalable Optimization Framework. IEEE Transactions on Communications, 70(2), 1423-1441.
  Xu, Dongfang; Jamali, Vahid; Yu, Xianghao; Ng, Derrick Wing Kwan & Schober, Robert
  
• Optimal Transmit Strategy for Multi-User MIMO WPT Systems With Non-Linear Energy Harvesters. IEEE Transactions on Communications, 70(3), 1726-1741.
  Shanin, Nikita; Cottatellucci, Laura & Schober, Robert
  
• Resource Allocation for Simultaneous Wireless Information and Power Transfer Systems: A Tutorial Overview. Proceedings of the IEEE, 110(1), 127-149.
  Wei, Zhiqiang; Yu, Xianghao; Ng, Derrick Wing Kwan & Schober, Robert