Improved Tx-to-Rx Isolation of Radar Transceivers Using Integrated Full Duplexer with PLL

Choi, Yeong Seok; Cho, Choon Sik; Kim, Young‐Jin

doi:10.1109/radar.2018.8557219

Cited by 3 publications

(3 citation statements)

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“…The fact that the receiver must be operating simultaneously while transmitting, and at the same carrier frequency, leads to large implementation challenges particularly in facilitating sufficient transmitter-receiver isolation [12], [19], [23], [28], [37]- [40]. This calls for new hardware, to replace the TDD RF switching with more elaborate circulator [20], [23]- [25] or EBD [12], [26], [27] type of circuitries, and has been studied actively over the recent years, under the inband full-duplex radio terminology, with primarily communications applications in mind, see, e.g., [19], [23], [37]- [45]. In the radar context, the self-interference (SI) stemming from the direct coupling of the transmit signal to the receiver can be interpreted as a strong static target at a very short distance [11], [12], [33], [46].…”

Section: Self-interference Problem and Cancellation Solutions A Tx-rx...mentioning

confidence: 99%

“…Then, we address a fundamental implementation challenge stemming from the limited TX-RX isolation [11], [19]- [22] in real base stations and the corresponding transmitter self-interference at the radar. Our main emphasis is on the challenging monostatic scenario where the same antenna system of the eNB/gNB is shared between the TX and RX, building, e.g., on a circulator [20], [23]- [25] or an electrical balance duplexer (EBD) [12], [26], [27]. We first observe that from the perspective of OFDM radar processing, the transmitter self-interference is the most problematic for static target detection while moving targets are already more robust.…”

mentioning

confidence: 99%

“…For clarity, it is acknowledged that TX-RX isolation is basically a known challenge in all continuous-wave radar systems, and that sufficient RF isolation is always needed to prevent receiver saturation [2], [12], [26], [28]. From the actual radar processing point of view, however, FMCW-type of constant-envelope radars [29]- [31] can largely suppress the remaining SI through down-mixing with the modulated transmit waveform in the receive path [29], [30].…”

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confidence: 99%

See 2 more Smart Citations

Full-Duplex OFDM Radar With LTE and 5G NR Waveforms: Challenges, Solutions, and Measurements

Barneto

Riihonen

Turunen

et al. 2019

IEEE Trans. Microwave Theory Techn.

227

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This paper studies the processing principles, implementation challenges, and performance of OFDM-based radars, with particular focus on the fourth-generation Long-Term Evolution (LTE) and fifth-generation (5G) New Radio (NR) mobile networks' base stations and their utilization for radar/sensing purposes. First, we address the problem stemming from the unused subcarriers within the LTE and NR transmit signal passbands, and their impact on frequency-domain radar processing. Particularly, we formulate and adopt a computationally efficient interpolation approach to mitigate the effects of such empty subcarriers in the radar processing. We evaluate the target detection and the corresponding range and velocity estimation performance through computer simulations, and show that highquality target detection as well as high-precision range and velocity estimation can be achieved. Especially 5G NR waveforms, through their impressive channel bandwidths and configurable subcarrier spacing, are shown to provide very good radar/sensing performance. Then, a fundamental implementation challenge of transmitter-receiver (TX-RX) isolation in OFDM radars is addressed, with specific emphasis on shared-antenna cases, where the TX-RX isolation challenges are the largest. It is confirmed that from the OFDM radar processing perspective, limited TX-RX isolation is primarily a concern in detection of static targets while moving targets are inherently more robust to transmitter self-interference. Properly tailored analog/RF and digital selfinterference cancellation solutions for OFDM radars are also described and implemented, and shown through RF measurements to be key technical ingredients for practical deployments, particularly from static and slowly moving targets' point of view.

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