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TR 38.889RAN1
Study on NR-based access to Unlicensed Spectrum

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V16.0.0 (Wzip)  2018/12  119 p.

WI Acronym:  FS_NR_unlic
Rapporteur:  Dr. Sun, JingQualcomm Incorporated

The purpose of this TR is to document the identified NR enhancements and corresponding evaluations for a single global solution framework for NR based access to unlicensed spectrum.
This TR addresses evaluation methodology and possible scenarios for NR based unlicensed deployments. It documents the existing regulatory requirements for unlicensed spectrum deployment in the 5GHz bands, and other bands.
This Study identifies and captures coexistence evaluations of physical layer options and enhancements to NR and, if necessary, NR RAN protocols to meet the requirements and targets for unlicensed spectrum deployments. It contains an assessment of the feasibility of base station and terminal operation of 5GHz band (based on regulatory limits) in conjunction with relevant licensed frequency bands.

full Table of Contents for  TR 38.889  Word version:   16.0.0

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1  ScopeWord-p. 7
2  References
3  Definitions, symbols and abbreviationsWord-p. 10
4  Regulatory requirementsWord-p. 12
4.1  Regulatory requirements for 5GHz band
The range 5150-5925 MHz, or parts thereof, is potentially available for license-assisted access to unlicensed operation. This represents a significant amount of spectrum that can be used by operators to augment their service offerings in licensed bands. The range above can be operated under a license-exempt regime or ISM but must be shared with existing mobile services and other incumbent services. The quality of service offered by a licensed regime can therefore not be matched. Hence, unlicensed access is viewed as complementary, and does not reduce the need for additional allocations for licensed operation in view of the increased demand for wireless broadband access.
It is relevant to consider the global (International) ITU-R allocations and technical provisions first. These could be basis for defining globally harmonised bands for LAA and starting points for requirements and limits before the local variations are considered.
5150-5350 and 5470-5725 MHz
WRC 2003 allocated the bands 5 150-5 350 MHz and 5 470-5 725 MHz on a co-primary basis to the mobile service for the implementation of "wireless access systems (WAS), including radio local area networks (RLANs)". This was subject to technical and regulatory provisions included in the radio regulations given in Resolution 229 (WRC-03), which was subsequently revised at WRC-12 to Resolution 229 (Rev. WRC-12) [38]. These provisions are followed by many Administrations and resolves:
  1. that the use of these bands by the mobile service will be for the implementation of WAS, including RLANs, as described in the most recent version of Recommendation ITU-R M.1450;
  2. that in the band 5 150-5 250 MHz, stations in the mobile service shall be restricted to indoor use with a maximum mean e.i.r.p. of 200 mW and a maximum mean e.i.r.p. density of 10 mW/MHz in any 1 MHz band or equivalently 0.25 mW/25 kHz in any 25 kHz band;
  3. that administrations may monitor whether the aggregate pfd levels given in Recommendation ITU-R S.1426 have been, or will be exceeded in the future, in order to enable a future competent conference to take appropriate action;
  4. that in the band 5 250-5 350 MHz, stations in the mobile service shall be limited to a maximum mean e.i.r.p. of 200 mW and a maximum mean e.i.r.p. density of 10 mW/MHz in any 1 MHz band. Administrations are requested to take appropriate measures that will result in the predominant number of stations in the mobile service being operated in an indoor environment.
  5. that administrations may exercise some flexibility in adopting other mitigation techniques, provided that they develop national regulations to meet their obligations to achieve an equivalent level of protection to the EESS (active) and the SRS (active) based on their system characteristics and interference criteria as stated in Recommendation ITU-R RS.1632;
  6. that in the band 5 470-5 725 MHz, stations in the mobile service shall be restricted to a maximum transmitter power of 250 mW3 (administrations with existing regulations prior to WRC 03 may exercise some flexibility in determining transmitter power limits) with a maximum mean e.i.r.p. of 1 W and a maximum mean e.i.r.p. density of 50 mW/MHz in any 1 MHz band;
  7. that in the bands 5 250-5 350 MHz and 5 470-5 725 MHz, systems in the mobile service shall either employ transmitter power control to provide, on average, a mitigation factor of at least 3 dB on the maximum average output power of the systems, or, if transmitter power control is not in use, then the maximum mean e.i.r.p. shall be reduced by 3 dB;
  8. that, in the bands 5 250-5 350 MHz and 5 470-5 725 MHz, the mitigation measures found in Annex 1 to Recommendation ITU-R M.1652-1 shall be implemented by systems in the mobile service to ensure compatible operation with radiodetermination systems,
This resolution makes DFS as described in the Annex 1 of ITU-R Recommendation M.1652-1 [39] mandatory, the basis for the DFS requirements developed e.g. in Europe and the US.
WAS is defined as end-user radio connections to public or private core networks, while primary allocation means that the services can claim protection from services of the secondary service. However, the WAS/RLAN services must protect the incumbent primary services.
Even if primary in the International table of allocations, this may not be the case in all countries. The bands are not allocated on a primary basis in the US allocation table, but to the Part 15 rules that provide for operation of low power radio transmitters without a license (secondary service operated on a non-interference basis).
5725-5850 MHz
The 5725-5875 MHz is allocated for ISM applications by means a footnote in the allocation table. Radiolocation is allocated on primary basis up to 5850 MHz so DFS is required up to this limit. Operation in 5725-5850 MHz is allowed in the US under the Part 15 rules (15.247 and 15.407).
5850-5925 MHz
The band is allocated to the mobile service on a primary basis in all regions. In Europe it has been decided (2008) to harmonise the use of the 5875-5925 MHz frequency band for Intelligent Transport Systems (ITS). Similarly, according to the US allocation table, the use of the non-Federal mobile service in the band 5850-5925 MHz is limited to Dedicated Short Range Communications operating in the Intelligent Transportation System radio service.
4.2  Regulatory requirements for 6GHz bandWord-p. 36
Currently, CEPT and FCC have started initiatives to investigate potentialities for deployment of IMT services in the 5.925-7.125 GHz frequency range (e.g. US 5925 - 7125 MHz, or European 5925 - 6425 MHz, or parts thereof), with considerations for all or part of this range being made available for unlicensed operation [TR 37.890].
5  Spectrum considerations
For the NR-U study item, different unlicensed bands or shared bands have been discussed, such as 2.4 GHz band, 3.5 GHz band, 5 GHz band, and 6 GHz band. Some bands are available globally and some bands are only available in some specific regions, and some bands may be made available after the completion of this study [TR 37.890].
Follow the NR design principles, from RAN1 design perspective, this NR-U study is not limited to a particular unlicensed band. Instead, the target NR-U design is applicable to a set of frequency ranges to be further defined. There is no prioritization between unlicensed bands. On the other hand, the NR-U study does not target sub-1 GHz unlicensed bands, due to the lack of spectrum in the band to support efficient NR-U operation.
6  Deployment scenarios
Five deployment scenarios have been identified:
  • Scenario A: Carrier aggregation between licensed band NR (PCell) and NR-U (SCell)
    • NR-U SCell may have both DL and UL, or DL-only.
  • Scenario B: Dual connectivity between licensed band LTE (PCell) and NR-U (PSCell)
  • Scenario C: Stand-alone NR-U
  • Scenario D: An NR cell with DL in unlicensed band and UL in licensed band
  • Scenario E: Dual connectivity between licensed band NR (PCell) and NR-U (PSCell)
7  Design targets, functionalities and solutions
8  Performance evaluations
9  Conclusions
A  Evaluation methodologyWord-p. 64
B  Evaluation resultsWord-p. 66
C  Change historyWord-p. 119

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