The present document captures the results and findings from the study item "Study on Evolution of NR Duplex Operation " [2]. The purpose of this TR is to document the follows for evolution of NR duplex operation:

• applicable and relevant deployment scenarios.
• evaluation methodology and assumptions.
• possible schemes/enhancements, feasibility and performance evaluation results of subband non-overlapping full duplex and dynamic/flexible TDD.
• summary of the regulatory aspects that have to be considered for deploying the identified duplex enhancements in TDD unpaired spectrum.

This activity involves the Radio Access work area of the 3GPP studies and has potential impacts both on the Mobile Equipment and Access Network of the 3GPP systems.

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.

• References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.

TDD is widely used in commercial NR deployments. In TDD, the time domain resource is split between downlink and uplink. Allocation of a limited time duration for the uplink in TDD would result in reduced coverage, increased latency and reduced capacity. As a possible enhancement on this limitation of the conventional TDD operation, it would be worth studying the feasibility of allowing the simultaneous existence of downlink and uplink, a.k.a. full duplex, or more specifically, subband non-overlapping full duplex at the gNB side within a conventional TDD band. The NR TDD specifications allow the dynamic/flexible allocation of downlink and uplink in time and CLI handling and RIM for NR were introduced in Rel-16. Nevertheless, further study may be required for CLI handling between the gNBs of the same or different operators to enable the dynamic/flexible TDD in commercial networks. The inter-gNB CLI may be due to either adjacent-channel CLI or co-channel-CLI, or both, depending on the deployment scenario. One of the problems not addressed in the previous releases is gNB-to-gNB CLI. This study aims to identify the feasibility and solutions of duplex evolution in the areas outlined above to provide enhanced UL coverage, reduced latency, improved system capacity, and improved configuration flexibility for NR TDD operations in unpaired spectrum. In addition, the regulatory aspects need to be examined for deploying identified duplex enhancements in TDD unpaired spectrum considering potential constraints.

The objective of this study is to identify and evaluate the potential enhancements to support duplex evolution for NR TDD in unpaired spectrum. In this study, the followings are assumed:

• Duplex enhancement at the gNB side
• Half duplex operation at the UE side
• No restriction on frequency ranges

The detailed objectives are as follows:

• Identify applicable and relevant deployment scenarios (RAN1).
• Develop evaluation methodology for duplex enhancement (RAN1).
• Study the subband non-overlapping full duplex and potential enhancements on dynamic/flexible TDD (RAN1, RAN4).
  • Identify possible schemes and evaluate their feasibility and performances (RAN1).
  • Study inter-gNB and inter-UE CLI handling and identify solutions to manage them (RAN1).
    • Consider intra-subband CLI and inter-subband CLI in case of the subband non-overlapping full duplex.
  • Study the performance of the identified schemes as well as the impact on legacy operation assuming their co-existence in co-channel and adjacent channels (RAN1).
  • Study the feasibility of and impact on RF requirements considering adjacent-channel co-existence with the legacy operation (RAN4).
  • Study the feasibility of and impact on RF requirements considering the self-interference, the inter-subband CLI, and the inter-operator CLI at gNB and the inter-subband CLI and inter-operator CLI at UE (RAN4).
  • Summarize the regulatory aspects that have to be considered for deploying the identified duplex enhancements in TDD unpaired spectrum (RAN4).