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

By Carlos Baquero Barneto, Taneli Riihonen, Matias Turunen, Lauri Anttila, Marko Fleischer, Kari Stadius, Jussi Ryynänen, Mikko Valkama. IEEE transactions on microwave theory and techniques, 2019

355 citations recorded by the source corpus.

This article studies the processing principles, implementation challenges, and performance of orthogonal frequency-division multiplexing (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. In particular, 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 high-quality target detection as well as high-precision range and velocity estimation can be achieved. In particular, 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 the detection of static targets, while moving targets are inherently more robust to transmitter self-interference (SI). Properly tailored analog/RF and digital SI 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.

Subfields: Aerospace Engineering, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/1c1fd06ab8bd2b137b76155e5453cfde62d251ec

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Citations in the corpus

Convergent Communication, Sensing and Localization in 6G Systems: An Overview of Technologies, Opportunities and Challenges (2021, background): “Radar-like localization solutions are also emerging based on 4G and 5G signals and advances in full-duplex communications [98]–[100], and it is likely to be expanded beyond 5G as well.”
Integrated Sensing and Communication in 6G: Motivations, Use Cases, Requirements, Challenges and Future Directions (2021, result): “In contrast to that, from the OFDM ISAC perspective, limited transmitter-receiver isolation is a primary concern in the detection of static targets [9].”
Integrated Sensing and Communication Signals Toward 5G-A and 6G: A Survey (2023, background): “[11], [113] indicated that promoting sufficient TX-RX isolation is a critical issue to be considered.”
Full-Duplex Communication for ISAC: Joint Beamforming and Power Optimization (2022, methodology): “By employing SIC techniques for ISAC systems [20], [21], the SI power can be mostly reduced.”
Joint Design of Communication and Sensing for Beyond 5G and 6G Systems (2021, background): “This self-interference would need to be mitigated [23] by a combination of antenna separation, as well as analog and digital interference cancellation.”
Integrated Sensing and Communications: Toward Dual-Functional Wireless Networks for 6G and Beyond (2021, background): “which is sufficient for a BS to identify a static drone at a distance of 40 m [161].”
The Integrated Sensing and Communication Revolution for 6G: Vision, Techniques, and Applications (2024, neutral): “This, in turn, means that such a sensor is essentially operating as an inband full-duplex (IBFD) transceiver, commonly also referred to as an STAR system [195], [196], [197].”
Enabling Joint Communication and Radar Sensing in Mobile Networks—A Survey (2020, methodology): “C) Full-duplex technologies in the context of JCAS for colocated transmitter and receiver, an analogy to the mono-static radar [39], [71] (More detailed in Section IV-B).”