3GPP Release 17 will be the next milestone towards the evolution of 5G. With a timeframe to be finalized by September 2021 (SA#93), 3GPP has allocated work items per radio technology for Release 17. Most work items of Release 17 focus on NR, while there are also a few LTE optimizations. 3GPP has already split the work for RAN1, dealing with the physical layer, RAN2 the radio protocol, and RAN3 for the radio architecture. The content of Release 17 for RAN1, RAN2 & RAN3 items have been identified in RAN#86 meeting in December ‘19, while RAN4 items are pending for approval at RAN#88, which is scheduled this June.
5G NR Enhancements
The NR enhancements are mainly targeted on the areas of Efficiency, New Radio features, service improvements, and NB-IoT/CAT-M evolution. RAN architecture evolution and SON/MDT analytics will improve NR efficiency, while new radio features such as MIMO, non-terrestrial networks, and new frequencies up to 71GHz will improve NR performance. Service improvements include enhancements on V2X side-link, Industrial IoT, and NR based positioning. At the same time, enhanced mobility and 16QAM modulation will increase the data rates and further enhance narrowband IoT and CAT-M technologies.
Physical layer enhancements (RAN1)
Release 17 will focus on further enhancements on MIMO technology for 5G NR. These enhancements include multi-beam operation, mainly targeting FR2 while also applicable to FR1, enhanced support for multi-TRP deployment, and improvements on SRS, focusing both on FR1 and FR2. Release 17 will also specify NR core requirements and investigate link recovery procedure requirements for FR2 serving cells.
There are also NR Sidelink enhancements targeting power savings, performance, and resource allocation to support vehicle-to-pedestrian (V2P) functionality. New Sidelink frequency bands for single-carrier operations are defined, together with a mechanism to ensure Sidelink operation to specific geographic areas for a given frequency range.
Release 17 is also extending NR operation up to 71 GHz. This work item extends NR operation above 52.6GHz up to 71GHz, considering both licensed and unlicensed operation in the 60 GHz WiGig band. NR/NR-U operation in the 52.6GHz to 71GHz can be in stand-alone or aggregated via CA or DC with an anchor carrier.
There are also enhancements on 5G NR Dynamic Spectrum Sharing (DSS). This work item is limited to FR1 and includes PDCCH enhancements for cross-carrier scheduling. This includes PDCCH of Secondary Cell scheduling and PDSCH or PUSCH on P(S)Cell.
In line with one of 5G’s main requirements, power saving functionality aims to improve 5G customer experience in terms of UE power consumption and provide better equipment standby and usage times. Release 17, will specify further Power Saving enhancements for idle/inactive-mode User Equipment, considering system performance aspects. Paging enhancements will also be specified within this work item, together with the means to provide potential TRS/CSI-RS occasions available in connected mode to idle/inactive-mode UEs, thus, minimizing system overhead impact.
Radio protocol enhancements (RAN2)
Release 17 also focuses on NR support of multicast and broadcast services, mainly for providing multicast possibilities within a specific cell, for example, in the case of automotive applications in a 5G point-to-multipoint subsystem. This work item specifies RAN essential functions for broadcast/ multicast for UEs in RRC_CONNECTED state. In more detail, it defines a group scheduling mechanism, support of dynamic change between broadcast and multicast services, and basic mobility functionalities. Furthermore, it enables UEs in RRC_IDLE/RRC_INACTIVE states to receive a point-to-multipoint transmission.
Further enhancements on Dual Connectivity will enable automatic activation and deactivation on a Secondary Cell Group and Secondary Cells. Multi-SIM devices will also be supported with enhancements of UE notification of a network switch, collision avoidance of receiving paging from multi-SIMs, and indication of voice traffic over NR or LTE.
NR over non-terrestrial networks is another aspect of Release 17 work items, for Operators that are using or planning to use satellite network transmission. This requires that UEs with GNSS will have to be used. Furthermore, low Earth orbit (LEO) and Geosynchronous Equatorial Orbit (GEO) satellite systems need to be compatible for supporting high altitude platform stations (HAPS) and air to ground (ATG) networks.
Another work item is enhancements to the integrated access & backhaul. This area deals with creating common relay sites known as IAB nodes (Integrated Access and Backhaul) that serve either as access and/or backhaul, sometimes sharing common physical resources. The enhancements are in the multiplexing of child and parent links in the IAB nodes, timing modes, and interference measurements, which will help simultaneous operation with the same physical resources.
Enhancements on Industrial IoT & URLLC communications will help 5G industry automation by guaranteeing compatibility with unlicensed bands, traffic handling and prioritizing with advanced QoS mechanisms, and synchronization.
Radio architecture enhancements (RAN3)
Release 17 will also focus on improvements for NR small data transmission, by creating 2 & 4 step RACH for Uplink RRC inactive state. This is expected to further increase battery lifetimes. Automation is going to be further enhanced by Self Organizing Networks (SON) and Minimization of Drive Tests (MDT) functionalities by automatically collecting network measurement data to provide flexible OAM optimization and mobility efficiency.
LTE Enhancements
3GPP Release 1 is not only focusing on NR but also on LTE optimization work items, such as Narrowband IoT and enhanced MTC. This specific work item focuses on 16QAM modulation for unicast UL/DL, including power allocation, and support for carrier selection and neighbor cell measurements. Another work item is the enhancement of LTE architecture to evolve to Control and User Plane Separation (CUPS) and specify the interfaces from the user to the control plane. No work for GSM or UMTS is currently initiated in Release 17.
Release 17 NR Studies
5G Coverage Extension is a study item that focuses on enhancing connectivity of devices by enabling extensive coverage in urban and rural scenarios for FR1 and indoor environment for FR2. Furthermore, it covers eMBB and VoIP services and FDD/TDD for FR1. Another study of Release 17 is on using mechanisms such as bandwidth and number of antennas reduction or techniques like half-duplex FDD to reduce device complexity. 3GPP has also created a study on NR eXtended Reality (XR) to identify traffic models to support XR, AR/VR, and Cloud Gaming applications and assess their performance. Another study is on IoT over Non-Terrestrial Networks (NTN) to identify scenarios such as sub6GHz frequency bands, PC3/PC5 device types to support NB IoT/eMTC services over satellite networks. Finally, there are also studies initiated to enhance NR positioning based on high-accuracy, KPIs and correction data, Real-time kinematic (RTK) positioning, on NR side-link layer 3 and Layer 2 relay and RAN slicing to support vertical applications.
