5G NR-U LAA: Coexistence of Wi-Fi and NR-U systems

To improve the capacity of cellular systems without additional expenses on licensed frequency bands, the 3GPP consort designed cellular technologies that use the unlicensed spectrum. The important peculiarity of the usage models of these technologies, the latest of which is New Radio Unlicensed (NR-U), is the coexistence with Wi-Fi networks deployed in the same frequency band. That is why NR-U uses channel access methods similar to those of Wi-Fi. However, the performance of Wi-Fi networks notably deteriorates in coexistence scenarios. One of the reasons is the slotted structure of transmissions of cellular base stations in the unlicensed spectrum, which may imply the use of a reservation signal (RS).

The WNL team have studied the coexistence of NR-U (and its predecessor in 4G cellular systems – LTE-LAA) and Wi-Fi in different conditions. First, we have investigated the performance of unlicensed cellular systems that do not use the reservation signals. According to the obtained results, the fair and efficient coexistence of Wi-Fi and LTE-LAA networks is almost impossible without RS, but the channel access without RS can be used in NR-U networks.

Next, we have shown that the reservation signal can lead to asymmetrical collisions of NR-U and Wi-Fi transmissions, which leads to significant Wi-Fi throughput drop. To solve this issue, we have proposed modifications to the RS structure to enable collision detection and collision resolution capabilities.

However, to reach the full potential of the technology, NR-U devices have to use several unlicensed channels simultaneously. 3GPP specification describes several multi-channel access methods, but does not provide guidance on the selection of the particular method in a particular scenario. The WNL team have studied the coexistence of Wi-Fi and NR-U in multi-channel scenarios and proposed modifications of the standard channel access methods to improve fairness. Finally, we have studied the coexistence of two NR-U operators in multi-channel scenarios, identified potential fairness and performance problems, and proposed channel access methods and channel selection strategies for fair and efficient coexistence of both operators.

List of relevant papers:


      2025
    1. Evgeny Khorov, Vyacheslav Loginov, Andrey Lyakhov. Coexistence of NR-U operators in multichannel scenarios: Fair cooperation or endless struggle for channel resources. // Ad Hoc Networks. – 2025. – С. 103798 doi: 10.1016/j.adhoc.2025.103798.

      2. 2022
    2. Evgeny Khorov, Vyacheslav Loginov, Andrey Lyakhov, Alexander Troegubov. Study of the collision resolution method in New Radio Unlicensed Networks with Multichannel Access of Type A. //Journal of Communications Technology and Electronics. – 2022. – Т. 67. – №. Suppl 2. – С. S248-S254. https://doi.org/10.1134/S1064226922140091.

      3. 2021
    3. Evgeny Khorov, Vyacheslav Loginov, Andrey Lyakhov, Ian F. Akyildiz. CR-LBT: Listen-before-Talk with Collision Resolution for 5G NR-U Networks. //IEEE Transactions on Mobile Computing. – 2021. – Т. 21. – №. 9. – С. 3138-3149. https://doi.org/10.1109/TMC.2021.3055028.
    4. Evgeny Khorov, Vyacheslav Loginov, Andrey Lyakhov, Alexander Troegubov. Enhanced Collision Resolution Methods With Mini-Slot Support for 5G NR-U. //IEEE Access. – 2021. – Т. 9. – С. 146137-146152. https://doi.org/10.1109/ACCESS.2021.3122953.

      5. 2020
    5. Evgeny Khorov, Vyacheslav Loginov, Andrey Lyakhov, Vyacheslav Zhdanovskiy. A Comparative Study on Multi-Channel Access Methods in 5G NR-U Networks. 3.In proc. of IEEE BlackSeaCom 2020, 26-29 May, 2020.

      6. 2019
    6. Evgeny Khorov, Vyacheslav Loginov, Andrey Lyakhov, Polina Kutsevol. Analytical Study of License-Assisted Access in 5G Networks. In proc. of IFIP Networking 2019, Warsaw, Poland, 20-22 May, 2019 .
    7. Vyacheslav Loginov, Andrey Lyakhov, Vyacheslav Zhdanovskiy. Performance Analysis of LBT with Limited Reservation Signal Duration for Fair LTE-LAA/Wi-Fi Coexistence. In proc. of IEEE BlackSeaCom 2019, Sochi, Russia, 3-6 June, 2019 .
    8. Evgeny Khorov, Vyacheslav Loginov, Andrey Lyakhov, Polina Kutsevol. New Collision Detection Method for Fair LTE-LAA and Wi-Fi Coexistence. In proc. of IEEE PIMRC 2019, Istanbul, Turkey, 8-11 September, 2019 .
    9. Evgeny Khorov, Vyacheslav Loginov, Andrey Lyakhov, Polina Kutsevol. Wireless Collision Detection for Fair LAA/Wi-Fi Coexistence . IEEE 802.11 Coexistence Workshop, Vienna, Austria, 17 July, 2019.
    10. Evgeny Khorov, Vyacheslav Loginov, Andrey Lyakhov, Polina Kutsevol. Mathematical Modeling of Joint Operation of Wireless Local Area Networks and Fifth Generation Cellular Networks. Automation and Remote Control, 2019, Vol. 80, No. 12, pp. 2163–2177.

      11. 2018
    11. Evgeny Khorov. xStream: a new platform for Application-aware Adaptive Network Slicing in 5G Systems (Tutorial). Global Information Infrastructure and Networking Symposium (GIIS 2018), Thessaloniki, Greece, 2018.