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TR 38.867
Study on NR Network-controlled Repeaters

V18.0.0 (Wzip)  2022/09  21 p.
Mr. Zhang, Nan
ZTE Corporation

full Table of Contents for  TR 38.867  Word version:  18.0.0

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1  Scopep. 6

The present document captures the findings from the study item "Study on NR Network-controlled Repeaters" [2].
The SI includes the study and identification of side control information (i.e., beamforming information, Timing information, information on UL-DL TDD configuration, ON-OFF information and power control information) for network-controlled repeaters and corresponding L1/L2 signaling (including its configuration) to carry the side control information. The scope of the study also includes the study on the aspects (i.e., identification and authorization) of network-controlled repeater management
The study on NR network-controlled repeaters is to focus on the following scenarios and assumptions:
  • Network-controlled repeaters are inband RF repeaters used for extension of network coverage on FR1 and FR2 bands, while during the study FR2 deployments may be prioritized for both outdoor and O2I scenarios.
  • For only single hop stationary network-controlled repeaters
  • Network-controlled repeaters are transparent to UEs
  • Network-controlled repeater can maintain the gNB-repeater link and repeater-UE link simultaneously

2  Referencesp. 6

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.
TR 21.905: "Vocabulary for 3GPP Specifications".
3GPP RP-213700: "New SI: Study on NR Network-controlled Repeaters".
TR 38.830: "Study on NR coverage enhancements".

3  Definitions of terms, symbols and abbreviationsp. 6

3.1  Termsp. 6

For the purposes of the present document, the terms given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.

3.2  Abbreviationsp. 6

For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905.
Network-controlled repeater
NCR-Mobile termination
Control link

4  Introductionp. 7

Coverage is a fundamental aspect of cellular network deployments. Mobile operators rely on different types of network nodes to offer blanket coverage in their deployments. Deployment of regular full-stack cells is one option but it may not always be possible (e.g., no availability of backhaul) or economically viable.
As a result, new types of network nodes have been considered to increase mobile operators' flexibility for their network deployments. For example, Integrated Access and Backhaul (IAB) was introduced in Rel-16 and enhanced in Rel-17 as a new type of network node not requiring a wired backhaul. Another type of network node is the RF repeater which simply amplify-and-forward any signal that they receive. RF repeaters have seen a wide range of deployments in 2G, 3G and 4G to supplement the coverage provided by regular full-stack cells. In Rel-17, RAN4 specified RF and EMC requirements for such RF repeaters for NR targeting both FR1 and FR2.
While an RF repeater presents a cost effective means of extending network coverage, it has its limitations. An RF repeater simply performs an amplify-and-forward operation without being able to take into account various factors that could improve performance. Such factors may include information on semi-static and/or dynamic downlink/uplink configuration, adaptive transmitter/receiver spatial beamforming, ON-OFF status, and so on.
A network-controlled repeater is an enhancement over conventional RF repeaters with the capability to receive and process side control information from the network. Side control information could allow a network-controlled repeater to perform the amplify-and-forward operation in a more efficient manner. Potential benefits could include mitigation of unnecessary noise amplification, transmissions and receptions with better spatial directivity, and simplified network integration.

5  Modelling of network-controlled repeaterp. 7

6  Side control informationp. 8

7  L1/L2 signalling for side control informationp. 9

8  Repeater managementp. 11

9  Performance evaluationp. 18

A  Cost evaluationsp. 20

$  Change historyp. 20

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