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Full-duplex (FD) wireless can significantly enhance spectrum efficiency but requires tremendous amount of selfinterference (SI) cancellation. Recent advances in the RFIC community enabled wideband RF SI cancellation (SIC) in integrated circuits (ICs) via frequency-domain equalization (FDE), where reconfigurable RF filters are used to channelize the SI signal path. In [2], we designed and implemented an FDEbased RF canceller on a printed circuit board (PCB). We also presented an optimized canceller configuration scheme based on the derived canceller model, and extensively evaluated the performance of the FDE-based FD radios in a softwaredefined radio (SDR) testbed in different network settings.
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Demo: Experimentation with Wideband Real-Time Adaptive Full-Duplex Radios
We present a set of experiments utilizing wideband real-time adaptive full-duplex (FD) radios, demonstrating simultaneous transmission and reception on the same frequency channel. Each FD radio consists of a circulator-based antenna interface, a switched-capacitor delay-line-based configurable Radio-Frequency Integrated Circuit (RFIC) that implements Self-Interference Cancellation (SIC), an FPGA that optimizes the RFIC configuration in under 1.1 sec and can adapt to environmental changes in under 0.3 sec, and a Software-Defined Radio (SDR) transmitting OFDM-like packets. We demonstrate a real-time adaptive FD radio that achieves the SIC necessary to reach the noise floor across a wide bandwidth of 50 MHz. Then, we use two FD radios to create a wireless link and showcase the superior FD throughput.
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- PAR ID:
- 10484353
- Publisher / Repository:
- ACM
- Date Published:
- Journal Name:
- ACM SIGCOMM'23
- ISBN:
- 9798400702365
- Page Range / eLocation ID:
- 1170 to 1172
- Format(s):
- Medium: X
- Location:
- New York NY USA
- Sponsoring Org:
- National Science Foundation
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null (Ed.)ABSTRACT In order to support experimentation with full-duplex (FD) wireless, we recently integrated two generations of FD radios in the open-access ORBIT and COSMOS testbeds. First, we integrated a customized 1st generation (Gen-1) narrowband FD radio in the indoor ORBIT testbed. Then, we integrated two 2 nd generation (Gen-2) wideband FD radios in the city-scale PAWR COSMOS testbed. Each integrated FD radio consists of an antenna, a customized RF self-interference (SI) canceller box, a USRP software-defined radio (SDR), and a remotely accessible compute node. The Gen-1/Gen-2 RF SI canceller box includes an RF canceller printed circuit board (PCB) which emulates a customized integrated circuit (IC) RF canceller implementation. The amplitude- and phase-based Gen-1 narrowband RF canceller achieves 40 dB RF SIC across 5 MHz. The Gen-2 wideband canceller is based on the technique of frequency-domain equalization (FDE) and achieves 50 dB RF SI cancellation (SIC) across 20 MHz. In this paper, we present the design and testbed integration of the two generations of FD radios. We then present example experiments that can be remotely run and modified by experimenters. Finally, we discuss future improvements and potential FD wireless experiments that can be supported by these open-access FD radios integrated in the COSMOS testbed.more » « less
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Full-duplex (FD) wireless can significantly enhance spectrum efficiency but requires tremendous amount of selfinterference (SI) cancellation. Recent advances in the RFIC community enabled wideband RF SI cancellation (SIC) in integrated circuits (ICs) via frequency-domain equalization (FDE), where RF filters channelize the SI signal path. Unlike other FD implementations, that mostly rely on delay lines, FDE-based cancellers can be realized in small-formfactor devices. However, the fundamental limits and higher layer challenges associated with these cancellers were not explored yet. Therefore, and in order to support the integration with a software-defined radio (SDR) and to facilitate experimentation in a testbed with several nodes, we design and implement an FDE-based RF canceller on a printed circuit board (PCB). We derive and experimentally validate the PCB canceller model and present a canceller configuration scheme based on an optimization problem. We then extensively evaluate the performance of the FDE-based FD radio in the SDR testbed. Experiments show that it achieves 95 dB overall SIC (52 dB from RF SIC) across 20 MHz bandwidth, and an average link-level FD gain of 1.87×. We also conduct experiments in: (i) uplink-downlink networks with inter-user interference, and (ii) heterogeneous networks with half-duplex and FD users. The experimental FD gains in the two types of networks confirm previous analytical results. They depend on the users’ SNR values and the number of FD users, and are 1.14×–1.25× and 1.25×–1.73×, respectively. Finally, we numerically evaluate and compare the RFIC and PCB implementations and study various design tradeoffs.more » « less
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Full-duplex (FD) wireless can signi�cantly enhance spectrum e�ciency but requires tremendous amount of selfinterference (SI) cancellation. Recent advances in the RFIC community enabled wideband RF SI cancellation (SIC) in integrated circuits (ICs) via frequency-domain equalization (FDE), where RF �lters channelize the SI signal path. Unlike other FD implementations, that mostly rely on delay lines, FDE-based cancellers can be realized in small-formfactor devices. However, the fundamental limits and higher layer challenges associated with these cancellers were not explored yet. Therefore, and in order to support the integration with a software-de�ned radio (SDR) and to facilitate experimentation in a testbed with several nodes, we design and implement an FDE-based RF canceller on a printed circuit board (PCB). We derive and experimentally validate the PCB canceller model and present a canceller con�guration scheme based on an optimization problem. We then extensively evaluate the performance of the FDE-based FD radio in the SDR testbed. Experiments show that it achieves 95 dB overall SIC (52 dB from RF SIC) across 20 MHz bandwidth, and an average link-level FD gain of 1.87⇥. We also conduct experiments in: (i) uplink-downlink networks with inter-user interference, and (ii) heterogeneous networks with half-duplex and FD users. The experimental FD gains in the two types of networks con�rm previous analytical results. They depend on the users’ SNR values and the number of FD users, and are 1.14⇥–1.25⇥ and 1.25⇥–1.73⇥, respectively. Finally, we numerically evaluate and compare the RFIC and PCB implementations and study various design tradeo�s.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3603269.3610853
