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1. A Full-Duplex Radio Using a CMOS Non-Magnetic Circulator Achieving +95 dB Overall SIC

   https://doi.org/10.1109/USNC-URSI.2019.8861766  

   Nagulu, Aravind; Chen, Tingjun; Zussman, Gil; Krishnaswamy, Harish (July 2019, in Proc. IEEE APS-URSI’19, July 2019.)

   Full-duplex (FD) wireless is an emerging wireless communication paradigm where the transmitter and the receiver operate simultaneously at the same frequency. One major challenge in realizing FD wireless is the interference of the TX signal saturating the receiver, commonly referred to self-interference (SI). Traditionally, self-interference cancellation (SIC) is achieved in the antenna, RF/analog, and digital domains. In the antenna domain, SIC can be achieved using a pair of separate TX and RX antennas, or using a single antenna shared by the TX and RX through a magnetic circulator, which is usually bulky, expensive, and not integrable with CMOS. Recent advances, however, have shown the feasibility of realizing high-performance non-reciprocal circulators in CMOS based on spatio-temporal modulation. In this work, we demonstrate a high power handling FD radio using a USRP SDR which employs SIC (i) at the antenna interface using a watt-level power-handling CMOS integrated, magnetic-free circulator, (ii) in the RF domain using a compact RF canceler, and (iii) in the digital domain. Our prototyped FD radio achieves +95 dB overall SIC at +15dBm TX power level. We analyze the effects of the circulator TX-RX non-linearity on the total achievable SIC 

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2. A Full-Duplex Radio Using a CMOS Non-Magnetic Circulator Achieving +95 dB Overall SIC

   Aravind Nagulu, Tingjun Chen (January 2019, URSI General Assembly and Scientific Symposium)

   Full-duplex (FD) wireless is an emerging wireless communication paradigm where the transmitter and the receiver operate simultaneously at the same frequency. One major challenge in realizing FD wireless is the interference of the TX signal saturating the receiver, commonly referred to self-interference (SI). Traditionally, self-interference cancellation (SIC) is achieved in the antenna, RF/analog, and digital domains. In the antenna domain, SIC can be achieved using a pair of separate TX and RX antennas, or using a single antenna shared by the TX and RX through a magnetic circulator, which is usually bulky, expensive, and not integrable with CMOS. Recent advances, however, have shown the feasibility of realizing high-performance non-reciprocal circulators in CMOS based on spatio-temporal modulation. In this work, we demonstrate a high power handling FD radio using a USRP SDR which employs SIC (i) at the antenna interface using a watt-level power-handling CMOS integrated, magnetic-free circulator, (ii) in the RF domain using a compact RF canceler, and (iii) in the digital domain. Our prototyped FD radio achieves +95 dB overall SIC at +15dBm TX power level. We analyze the effects of the circulator TX-RX non-linearity on the total achievable SIC. 

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3. Programmable and Open-Access Millimeter-Wave Radios in the PAWR COSMOS Testbed

   https://doi.org/10.1145/3477086.3480834  

   Chen, Tingjun; Maddala, Prasanthi; Skrimponis, Panagiotis; Kolodziejski, Jakub; Gu, Xiaoxiong; Paidimarri, Arun; Rangan, Sundeep; Zussman, Gil; Seskar, Ivan (October 2021, Proc. ACM MobiCom’21 Workshop on Wireless Network Testbeds, Experimental evaluation & CHaracterization (WiNTECH’21) (to appear))

   null (Ed.)

   While millimeter-wave (mmWave) wireless has recently gained tremendous attention with the transition to 5G, developing a broadly accessible experimental infrastructure will allow the research community to make significant progress in this area. Hence, in this paper, we present the design and implementation of various programmable and open-access 28/60 GHz software-defined radios (SDRs), deployed in the PAWR COSMOS advanced wireless testbed. These programmable mmWave radios are based on the IBM 28 GHz 64-element dual-polarized phased array antenna module (PAAM) subsystem board and the Sivers IMA 60 GHz WiGig transceiver. These front ends are integrated with USRP SDRs or Xilinx RF-SoC boards, which provide baseband signal processing capabilities. Moreover, we present measurements of the TX/RX beamforming performance and example experiments (e.g., real-time channel sounding and RFNoC-based 802.11ad preamble detection), using the mmWave radios. Finally, we discuss ongoing enhancement and development efforts focusing on these radios. 

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4. Programmable and Open-Access Millimeter-Wave Radios in the COSMOS Testbed: Design, Deployment, and Experimentation,”

   T. Chen, P. Maddala (October 2023, Computer networks communications)

   While millimeter-wave (mmWave) wireless has recently gained tremendous attention with the transition to 5G, developing a broadly accessible experimental infrastructure will allow the research community to make significant progress in this area. Hence, in this paper, we present the design and implementation of various programmable and open-access 28/60 GHz software-defined radios (SDRs), deployed in the PAWR COSMOS advanced wireless testbed. These programmable mmWave radios are based on the IBM 28 GHz 64-element dual-polarized phased array antenna module (PAAM) subsystem board and the Sivers IMA 60 GHz WiGig transceiver. These front ends are integrated with USRP SDRs or Xilinx RFSoC boards, which provide baseband signal processing capabilities. Moreover, we present measurements of the TX/RX beamforming performance and example experiments (e.g., real-time channel sounding and RFNoC-based 802.11ad preamble detection), using the mmWave radios. Finally, we discuss ongoing enhancement and development efforts focusing on these radios. 

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5. Magnetoelectric Versus Inductive Power Delivery for Sub-mm Receivers

   https://doi.org/10.1109/WPTC51349.2021.9458201  

   Khalifa, Adam; Nasrollahpour, Mehdi; Sun, Neville; Zaeimbashi, Mohsen; Chen, Huaihao; Liang, Xianfeng; Alemohammad, Milad; Etienne-Cummings, Ralph; Sun, Nian X.; Cash, Sydney (January 2021, 2021 IEEE MTT-S Wireless Power Transfer Conference (WPTC 2021))

   Most of the next-generation implantable medical devices that are targeting sub-mm scale form factors are entirely powered wirelessly. The most commonly used form of wireless power transfer for ultra-small receivers is inductive coupling and has been so for many decades. This might change with the advent of novel microfabricated magnetoelectric (ME) antennas which are showing great potential as high-frequency wireless powered receivers. In this paper, we compare these two wireless power delivery methods using receivers that operate at 2.52 GHz with a surface area of 0.043 mm2 . Measurement results show that the maximum achievable power transfer of a ME antenna outperforms that of an on-silicon coil by approximately 7 times for a Tx-Rx distance of 2.16 and 3.3 times for a Tx-Rx distance of 0.76 cm. 

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