Content for TR 38.844 Word version: 18.0.0
0 Introduction
1 Scope
2 References
3 Definitions of terms, symbols and abbreviations
3.1 Terms
3.2 Symbols
3.3 Abbreviations
4 Background
4.1 Objectives
5 General
5.1 UE channel bandwidth
...
...
0 Introduction p. 6
One of the aims of 5G is providing bandwidth flexibility. Although this is achieved in general, but for some spectrum allocations the ability to achieve such flexibility needs further study.
1 Scope p. 7
The present document is the Technical Report of the Study Item on Efficient utilization of licensed spectrum that is not aligned with existing NR channel bandwidths, approved at TSG RAN #89-e [2]. The purpose of this document is to capture and document the outcome of the objectives stated in the SID.
2 References p. 7
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.
[1]
TR 21.905: "Vocabulary for 3GPP Specifications".
[2]
RP-202103: SID "Study on Efficient utilization of licensed spectrum that is not aligned with existing NR channel bandwidths"
[3]
R4-2200031: Reply LS on specification impact for methods on efficient utilization of licensed spectrum that is not aligned with existing NR channel bandwidths, RAN2
[4]
R4-2119411: Reply LS on specification impact for methods on efficient utilization of licensed spectrum that is not aligned with existing NR channel bandwidths, RAN1
[5]
R2-1902778: "Clarification to channel bandwidth signalling", Nokia, Nokia Shanghai Bell, Qualcomm
3 Definitions of terms, symbols and abbreviations p. 7
3.1 Terms p. 7
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.
Larger Channel BW than licensed BW:
Uses the closest NR channel bandwidth defined in Rel-17 which is larger/wider than the irregular bandwidth. Also referred to as Next Wider CBW.
Irregular bandwidth:
an NR bandwidth that is not defined in Rel-17
Overlapping UE channel BW from network perspective:
network supports the irregular bandwidth (either by a single carrier or by two overlapping carriers) while each UE operates in an existing lower regular NR channel bandwidth
Combined UE channel BW (one cell):
network supports the irregular bandwidth as well as some new UEs with support of two overlapping (RF) carriers. Also referred to as Overlapping UE channel BW from UE perspective.
Overlapping CA:
the irregular bandwidth is handled by two overlapping component carriers (CCs) with NR channel bandwidth defined in Rel-17. It is network responsibility to prevent collisions between the different component carriers.
Single BB carrier:
means that from baseband (RAN1) perspective, there is a single cell with a waveform according to a single carrier
3.2 Symbols p. 8
For the purposes of the present document, the following symbols apply:
3.3 Abbreviations p. 8
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.
ACLR
Adjacent Channel Leakage Ratio
ACS
Adjacent Channel Selectivity
BS
Base Station
BW
Bandwidth
CBW
Channel Bandwidth
FR1
Frequency Range 1
OBUE
Operating Band Unwanted Emissions
RF
Radio Frequency
SCBW
Smaller Channel Bandwidth (Existing immediate lower channel bandwidth)
UE
User Equipment
WCBW
Wider Channel Bandwidth (Existing immediate wider channel bandwidth)
4 Background p. 8
One of the aims of 5G is providing bandwidth flexibility. Although this is achieved in general, for some spectrum allocations the ability to achieve such flexibility needs further study.
Solutions for the following spectrum allocations have been requested so far:
| Band (s) | Channel Bandwidth(s) |
|---|---|
| n5 | 7, 11 MHz |
| n12, n85 | 6, 12 MHz |
| n26 | 7 MHz |
| n28 | 13 MHz |
| n29 | 6, 11 MHz |
Some techniques have been suggested for re-using existing channel bandwidths which can include but are not limited to overlapping UE channel bandwidths, and/or using larger bandwidths than operator licensed bandwidth. This Study Item is needed to evaluate where existing techniques can be used to efficiently utilize operator spectrum allocations, and whether and how new channel bandwidths should be created. The Study shall also analyse if a proprietary solution(s) is sufficient.
4.1 Objectives p. 8
The following objectives are listed in the SID [2]
-
Identify operator licensed channel bandwidths in FR1 that do not align with existing NR channel bandwidths.
- Only licensed spectrum wider than 5 MHz to be considered in this SID.
- Spectrum block of 33MHz in n28 require further investigation since there is dual duplexer assumption (2x30MHz) for this band.
- Evaluate the potential use of larger channel bandwidths than operator licensed bandwidth, including the impacts on regulatory emission requirements/UE output power implications and UE ACS/blocking impacts depending on the guard band and the SCS.
- Study the use of overlapping UE channel bandwidths (from both UE and network perspective) to cover operator's license spectrum for both UL and DL, and if new gNB channel bandwidths are needed.
- Identify operator licensed bandwidths that are not compatible with the use of techniques like overlapping UE channel bandwidths. Every proposed method shall be summarized with respect to whether all considered spectrum scenarios are supported or whether there are specific limitations. Some limitations for a specific method shall not disqualify such method if there is a trade-off between flexibility and implementation challenges.
- Study the complexity and efficiency of adding new channel bandwidths vs. using other including testing aspects.
- Generic solution(s) should be intended as much as possible, with priority should be given to approaches that avoid the introduction of new channel BWs on the UE side. Proprietary solutions if proven relevant should not be precluded. Spectrally efficient methods providing a fine channel bandwidth granularity as well as low to moderate guard band width and signalling overhead should be preferred
- Impact on RAN1 and RAN2 should be considered and minimized
- For any considered solution, Ues not supporting such solution (both legacy and new Ues) should be able to use the next lower supported channel bandwidth in the UL and DL without implications.
- Impact (if any) on RAN4 requirements should be identified for the preferred solutions.
5 General p. 9
5.1 UE channel bandwidth p. 9
The following text is copied from TS 38.101-1 for information:
The UE channel bandwidth supports a single NR RF carrier in the uplink or downlink at the UE. From a BS perspective, different UE channel bandwidths may be supported within the same spectrum for transmitting to and receiving from Ues connected to the BS. Transmission of multiple carriers to the same UE (CA) or multiple carriers to different Ues within the BS channel bandwidth can be supported.
From a UE perspective, the UE is configured with one or more BWP / carriers, each with its own UE channel bandwidth. The UE does not need to be aware of the BS channel bandwidth or how the BS allocates bandwidth to different Ues.
The placement of the UE channel bandwidth for each UE carrier is flexible but can only be completely within the BS channel bandwidth.
