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

C. Baquero Barneto, T. Riihonen, Matias Turunen, L. Anttila, M. Fleischer, K. Stadius, J. Ryynänen, Mikko Valkama

Research output: Contribution to journalArticleScientificpeer-review

144 Citations (Scopus)


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.
Original languageEnglish
Article number8805161
Pages (from-to)4042-4054
Number of pages13
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number10
Early online date2019
Publication statusPublished - Oct 2019
MoE publication typeA1 Journal article-refereed


  • Analog cancellation
  • digital cancellation
  • 5G New Radio (NR)
  • in-band full-duplex
  • joint communications and sensing
  • Long-Term Evolution (LTE)
  • orthogonal frequency-division multiplexing (OFDM)
  • radar
  • RF convergence
  • self-interference (SI).


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