Novel Modulated Backscattered Communication Techniques for Transponder Based on Multiple Antennas

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School of Electrical Engineering | Doctoral thesis (article-based) | Defence date: 2022-05-18
Degree programme
87 + app. 47
Aalto University publication series DOCTORAL THESES, 59/2022
Recently, existing ambient radio frequency (RF) signals such as those from Wi-Fi APs, Bluetooth devices, TV towers, FM broadcasting stations and cellular base stations have been proposed to be reused for backscatter communication as they can, in principle, provide power continuously. In this context, an advanced version of RFID technology with sensing capabilities can play a pivotal role in the large-scale deployment of the Internet of Things (IoT). However, the RF sources in ambient backscatter communications systems (ABCSs) are unpredictable regarding transmission powers, frequencies and locations. Therefore, the design and deployment of an ambient backscatter device to achieve optimal performance is often more complicated. Clearly, a single antenna will not be sufficient, given the requirement for a long read range with high-speed data communication in sensor nodes operating over a wide range of frequencies. Multiple antennas should instead be employed for efficient operation. Smart antenna solutions such as frequency-reconfigurable antennas, beam-and-polarization steerable antennas are needed with more advanced modulators.The first part of the thesis presents a new concept of transponder that can independently perform amplitude and phase modulation. Such a modulator enables modulation schemes that necessitate multiple states. Multi-state modulation schemes can possibly carry more bits per a unit time at the same modulation frequency. The second part of the thesis introduces a broadband transponder concept that enables the device to select the frequency band with the highest power density. Multiple, closely spaced antenna elements with adjustable phase weighting are combined to create a transponder that can be tuned to function across many frequency bands. The theory necessary to support this objective is formulated, and the concept is experimentally verified. The last part of the thesis aims to design a beam-steerable transponder capable of independently steering at least two beams simultaneously by adjusting modulator delays. This allows the device to receive signals from one direction and re-scatter them to another. Alternatively, the device can gather energy from two directions simultaneously. The operation principle with an analytical model is explained for both monostatic and bistatic cases and the most feasible structure and control circuit are demonstrated in practice.
Supervising professor
Viikari, Ville, Prof., Aalto University, Department of Electronics and Nanoengineering, Finland
Thesis advisor
Holopainen, Jari, Dr., Aalto University, Finland
antenna cluster, antenna array, backscattering, beam steering, broadband transponder, frequency reconfigurability, IoT, phase weighting, rescattering, load modulation, WSNs
Other note
  • [Publication 1]: T. A. Siddiqui, M. Islam, K. Rasilainen and V. Viikari, “Transponder utilizing the modulated re-scattering communication principle,” 32nd URSI General Assembly and Scientific Symposium, Montreal, Canada, 19–26 Aug 2017.
    DOI: 10.23919/URSIGASS.2017.8105144 View at publisher
  • [Publication 2]: T. A. Siddiqui, P. Khanal, J. Holopainen and V. Viikari, “Broadband Transponder Based on Frequency-Reconfigurable Cluster Antenna and Phased Modulators,” IEEE Antennas and Wireless Propagation Letters, vol. 19, no. 2, pp. 238–242, Feb 2020.
    DOI: 10.1109/LAWP.2019.2958181 View at publisher
  • [Publication 3]: T. A. Siddiqui, P. Khanal, J. Holopainen and V. Viikari, “Further Investigation of a Frequency-Reconfigurable Transponder on the Basis of aMutually Coupled Antenna Cluster and Phased Modulators,” URSI Radio Science Letters, vol. 2, Sep 2020
  • [Publication 4]: T. A. Siddiqui, J. Holopainen, and V. Viikari, “Ambient Backscattering Transponder with Independently Switchable Rx and Tx Antennas,” IEEESensors Letters, vol. 3, no. 5, May 2019.
    Full text in Acris/Aaltodoc:
    DOI: 10.1109/LSENS.2019.2909184 View at publisher
  • [Publication 5]: T. A. Siddiqui, P. Khanal, J. Holopainen and V. Viikari, “Concept of Beam Steerable Transponder Based on Load Modulation,” In 14th European Conference on Antennas and Propagation (EuCAP), Copenhagen, Denmark, 15–20 March 2020.
    Full text in Acris/Aaltodoc:
    DOI: 10.23919/EuCAP48036.2020.9135510 View at publisher
  • [Publication 6]: T. A. Siddiqui, J. Holopainen and V. Viikari, “Beam-Steerable Transponder Based on Antenna Array and Phased Modulators,” IEEE Antennas andWireless Propagation Letters, vol. 20, no. 3, pp. 356–360, March 2021.
    DOI: 10.1109/LAWP.2021.3049972 View at publisher