This document captures the findings from the study item "Study on support of reduced capability NR devices" .
The study includes identification and study of potential UE complexity reduction techniques and UE power saving and battery lifetime enhancements for reduced capability UEs in applicable use cases, functionality that will enable the performance degradation of such complexity reduction to be mitigated or limited, principles for how to define and constrain such reduced capabilities, and functionality that will allow devices with reduced capabilities to be explicitly identifiable to networks and networks operators and allow operators to restrict their access if desired.
The scope of the study includes support for all FR1/FR2 bands for FDD and TDD and coexistence with Rel-15/16 UEs. This study focuses on SA mode and single connectivity. The scope of the study does not include LPWA use cases.
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.
: "Vocabulary for 3GPP Specifications".
3GPP RP-201677: "Revised SID on support of reduced capability NR devices".
3GPP R1-2009293: "FL summary on RedCap evaluation results".
: "Study on provision of low-cost Machine-Type Communications (MTC) User Equipments (UEs) based on LTE".
: "Study on NR coverage enhancements".
: "Study on User Equipment (UE) power saving in NR".
3GPP R1-070674: "LTE physical layer framework for performance verification", Orange, China Mobile, KPN, NTT DoCoMo, Sprint, T-Mobile, Vodafone, Telecom Italia.
3GPP R2-2009116: "Further considerations for eDRX", MediaTek.
3GPP R2-2009620: "RedCap power saving enhancements", Ericsson.
3GPP R2-2100459: "TP for TR 38875 on evaluation for RRM relaxation", vivo, Guangdong Genius.
3GPP R2-2101257: "RRM measurement relaxation for RedCap UE", Huawei, HiSilicon.
: "Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2".
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
For convenience only, a RedCap UE refers to an NR UE with reduced capabilities with details described herein.
For the purposes of the present document, the following symbols apply:
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
The usage scenarios that have been identified for 5G are enhanced mobile broadband (eMBB), massive machine-type communication (mMTC), and Ultra-Reliable and Low Latency communication (URLLC). Yet another identified area is time sensitive communication (TSC). In particular, mMTC, URLLC and TSC are associated with novel IoT use cases that are targeted in vertical industries. It is envisaged that eMBB, mMTC, URLLC and TSC use cases may all need to be supported in the same network.
In the 3GPP study on "self-evaluation towards IMT-2020 submission" it was confirmed that NB-IoT and LTE-MTC (a.k.a. eMTC) fulfil the IMT-2020 requirements for mMTC and can be certified as 5G technologies. For URLLC support, URLLC features were introduced in Release 15 for both LTE and NR, and NR URLLC is further enhanced in Release 16 within the enhanced URLLC (eURLLC) and Industrial IoT work items. Rel-16 also introduced support for Time-Sensitive Networking (TSN) and 5G integration for TSC use cases.
One important objective of 5G is to enable connected industries. 5G connectivity can serve as catalyst for next wave of industrial transformation and digitalization, which improve flexibility, enhance productivity and efficiency, reduce maintenance cost, and improve operational safety. Devices in such environment include e.g. pressure sensors, humidity sensors, thermometers, motion sensors, accelerometers, actuators, etc. It is desirable to connect these sensors and actuators to 5G radio access and core networks. The massive industrial wireless sensor network (IWSN) use cases and requirements described in TR 22.804, TS 22.104, TR 22.832 and TS 22.261 include not only URLLC services with very high requirements, but also relatively low-end services with the requirement of small device form factors, and/or being completely wireless with a battery life of several years. The requirements for these services are higher than LPWA (i.e. LTE-MTC/NB-IoT) but lower than URLLC and eMBB.
Similar to connected industries, 5G connectivity can serve as catalyst for the next wave smart city innovations. As an example, TR 22.804 describes smart city use case and requirements for that. The smart city vertical covers data collection and processing to more efficiently monitor and control city resources, and to provide services to city residents. Especially, the deployment of surveillance cameras is an essential part of the smart city but also of factories and industries.
Finally, wearables use case includes smart watches, rings, eHealth related devices, and medical monitoring devices etc. One characteristic for the use case is that the device is small in size.
As a baseline, the requirements for these three use cases are:
Device complexity: Main motivation for the new device type is to lower the device cost and complexity as compared to high-end eMBB and URLLC devices of Rel-15/Rel-16. This is especially the case for industrial sensors.
Device size: Requirement for most use cases is that the standard enables a device design with compact form factor.
Deployment scenarios: System should support all FR1/FR2 bands for FDD and TDD.
Use case specific requirements:
Industrial wireless sensors: Reference use cases and requirements are described in TR 22.832 and TS 22.104: Communication service availability is 99.99% and end-to-end latency less than 100 ms. The reference bit rate is less than 2 Mbps (potentially asymmetric e.g. UL heavy traffic) for all use cases and the device is stationary. The battery should last at least few years. For safety related sensors, latency requirement is lower, 5-10 ms (TR 22.804)
Video Surveillance: As described in TR 22.804, reference economic video bitrate would be 2-4 Mbps, latency < 500 ms, reliability 99%-99.9%. High-end video e.g. for farming would require 7.5-25 Mbps. It is noted that traffic pattern is dominated by UL transmissions.
Wearables: Reference bitrate for smart wearable application can be 5-50 Mbps in DL and 2-5 Mbps in UL and peak bit rate of the device higher, up to 150 Mbps for downlink and up to 50 Mbps for uplink. Battery of the device should last multiple days (up to 1-2 weeks).
The intention is to study a UE feature and parameter list with lower end capabilities, relative to Release 16 eMBB and URLLC NR to serve the three use cases mentioned above.
The study includes the following objectives:
Identify and study potential UE complexity reduction features, including [RAN1, RAN2]:
Reduced number of UE RX/TX antennas
UE bandwidth reduction
Relaxed UE processing time
Relaxed UE processing capability
Rel-15 SSB bandwidth should be reused and L1 changes minimized.
The work defined above should not overlap with LPWA use cases.
The lowest data rate and bandwidth capability considered should be no less than an LTE Category 1bis modem.
The study includes evaluations of the impact to coverage, network capacity and spectral efficiency.
Study UE power saving and battery lifetime enhancement for reduced capability UEs in applicable use cases (e.g. delay tolerant) [RAN2, RAN1]:
Reduced PDCCH monitoring by smaller numbers of blind decodes and CCE limits [RAN1].
Extended DRX for RRC Inactive and/or Idle [RAN2]
RRM relaxation for stationary devices [RAN2]
Study functionality that will enable the performance degradation of such complexity reduction to be mitigated or limited, including [RAN1]:
Coverage recovery to compensate for potential coverage reduction due to the device complexity reduction.
For FR1, coverage analysis for wearables can include consideration of potential reduced antenna efficiency due to device size limitations as part of the antenna gains. The extent of additional recovery of coverage loss due to reduced antenna efficiency is to be limited to 3 dB.
The study includes evaluations of the impact to network capacity and spectral efficiency.
Note: Potential overlap with the Coverage Enhancement SI  is discussed and resolved in RAN plenary.
Study standardization framework and principles for how to define and constrain such reduced capabilities - considering definition of a limited set of one or more device types and considering how to ensure those device types are only used for the intended use cases [RAN2, RAN1].
Study functionality that will allow devices with reduced capabilities to be explicitly identifiable to networks and network operators, and allow operators to restrict their access, if desired [RAN2, RAN1].
Coexistence with Rel-15 and Rel-16 UE should be ensured.
This SI should focus on SA mode and single connectivity.