Terms and abbreviations
5GS 5G System
AAS Advanced Antenna System
AI Artificial Intelligence
CSI Channel State Information
DNS Domain Name System
DSS Dynamic Spectrum Sharing
EASDF Edge Application Server Discovery Function
eMBB Enhanced Mobile Broadband
FR Frequency Range
gNB gNodeB
HST High-Speed Train
IAB Integrated Access and Backhaul
IIoT Industrial Internet of Things
IoT Internet of Things
LEO Low Earth Orbit
LTE-M LTE for Machine Type Communication
MBB Mobile Broadband
MBS Multicast and Broadcast Service
MIMO Multiple-Input, Multiple-Output
ML Machine Learning
MMTC Massive Machine-Type Communication
mTRP multiple Transmission and Reception Point
NB-IoT Narrowband-IoT
NC-JT Non-Coherent Joint Transmission
NF Network Function
NPN Non-Public Network
NR New Radio
NR-U NR-Unlicensed
NSPS National Security and Public Safety
NTN Non-Terrestrial Networks
NWDAF Network Data and Analytics Function
PDCCH Physical Downlink Control Channel
PDSCH Physical Downlink Shared Channel
PDU Protocol Data Unit
PHY Physical Layer
PUCCH Physical Uplink Control Channel
PUSCH Physical Uplink Shared Channel
RAN Radio Access Network
RAT Radio-Access Technology
RedCap Reduced Capability
RRC Radio Resource Control
RTT Round-Trip Time
RX Radio Receiver
SFN Single-Frequency Network
SNPN Standalone NPN
SRS Sounding Reference Signal
TRP Transmission and Reception Point
TSC Time-Sensitive Communication
TSN Time-Sensitive Networks
TX Radio Transmitter
UE User Equipment
URLLC Ultra-Reliable, Low-Latency Communication
URSP UE Route-Selection Policy
V2X Vehicle-to-Everything
XR Extended Reality
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Together with enhancements aimed at existing use cases such
as mobile broadband, industrial automation and
vehicle-to-everything, 3GPP release 17 introduces support for
new ones including public safety, non-terrestrial networks and
non-public networks. Meanwhile, the early planning of release 18
indicates that it will significantly evolve 5G in the areas of
artificial intelligence and extended reality.
The 3GPP has passed the midpoint in its work on its release 17
(Rel-17) specifications, with plans to publish them at the end
of the first quarter of 2022. Meanwhile, the discussions on the
scope of Rel-18 are well underway. In fact, 3GPP has already
announced its decision to recognize Rel-18 as the first release
of 5G Advanced to highlight the significant evolution of the 5G
System (5GS) that it represents.
Several of the features in Rel-17 are intended to enhance
network performance for existing services and use cases, while
others address new use cases and deployment options. 5G Advanced
will build on Rel-17, providing intelligent network solutions
and covering numerous new use cases in addition to previously
defined use cases and deployment options. Figure 1 shows
Ericssons view on 3GPPs tentative time plan for releases up
until 2028.
.
Figure 1 : 3GPPs 5G evolution tentative time plan
One key component of 5G Advanced is the use of
artificial intelligence (AI) based on machine learning (ML)
techniques. AI/ML is expected to trigger a paradigm shift in
future wireless networks. AI/ML-based solutions will be used to
introduce intelligent network management and solve
multi-dimensional optimization issues with respect to real-time
and non-real-time network operation.
AI/ML will also be used to improve the radio interface by
further optimizing the performance of complex multi-antenna
systems, for example. New use cases such as extended reality (XR)
communication will use wireless networks to provide immersive
experiences in cyber-physical environments and enable
human-machine interactions using wireless devices and wearables.
Enhancements in 3GPP release 17
The path toward 5G Advanced begins with Rel-17, which includes
significant enhancements to several radio access network (RAN)
functionalities that are already deployed in live New Radio (NR)
networks.
Beamforming and multiple-input, multiple-output (MIMO)
As shown in Figure 2, Rel-17 MIMO enhancements address four
areas: beam management; multiple transmission and reception
point (mTRP) for ultra-reliable, low-latency communication (URLLC);
mTRP for enhanced mobile broadband (eMBB); and TDD and FDD
reciprocity.
Figure 2: Rel-17 NR MIMO enhancement areas
The multi-beam enhancements are intended to improve performance
at high mobility by streamlining signaling and to optimize
performance for user equipment (UE) with multiple antenna
panels. The mTRP enhancements increase robustness for the
physical downlink control channel (PDCCH), physical uplink
shared channel (PUSCH) and physical uplink control channel (PUCCH).
They also enable richer channel state information (CSI) feedback
for non-coherent joint transmission (NC-JT) and optimize
performance for high-speed-train (HST) communication scenarios.
Finally, the enhancements to reciprocity-based operation include
new codebooks with reduced feedback overhead, where partial
channel knowledge is available at gNodeB (gNB), as well as
improvements to the Sounding Reference Signals (SRSs).
Dynamic spectrum sharing
The dynamic spectrum sharing (DSS) included in Rel-15 already
makes it possible to deploy an LTE cell and an NR cell on the
same base station using shared spectrum, which enables an
operator to provide 5G services by initiating a migration of
spectrum from LTE to NR. Rel-16 primarily improved the capacity
of the NR physical downlink shared channel (PDSCH). Enhancements
in Rel-17 make it easier for operators to overcome PDCCH
resource shortages in the NR cell, which can occur as the number
of NR UEs increases. From Rel-17 onwards, cross-carrier
scheduling allows for the data channels to be scheduled on the
shared primary cell using the PDCCH of a downlink secondary
cell.
User equipment power savings
Rel-17 includes power-saving enhancements for UEs in Radio
Resource Control (RRC) connected, idle and inactive modes.
Power-efficiency improvements are specified both for eMBB UEs
and reduced-capability (RedCap) devices. The list of
power-saving enhancements includes relaxed radio resource
monitoring for devices operating at low mobility or in very good
radio conditions, extended discontinuous reception (eDRX) for
latency-tolerant devices, reduced PDCCH monitoring during active
time, and power-efficient paging reception.
Positioning
NR has supported positioning since Rel-15 through the use of LTE
positioning (for non-standalone deployments) and radio-access
technology (RAT) independent positioning (Bluetooth, wireless
LAN, pressure sensors and so on). Rel-16 introduced time-based
positioning methods for NR standalone deployments
(multi-round-trip time (RTT), Downlink and Uplink Time
Difference of Arrival), as well as an angle-of-arrival and
angle-of-departure-based positioning measurements, which can be
used in combination with timing-based solutions to achieve
higher accuracy.
In Rel-17, NR positioning is further improved for specific use
cases such as factory automation by targeting 20-30cm location
accuracy for certain deployments. Rel-17 also introduces further
enhancements to latency reduction to enable positioning in
time-critical use cases such as remote-control applications.
Aside from high-positioning accuracy, industrial Internet of
Things (IIoT) and automotive use cases also demand integrity
protection of the location information. From a higher layer
point of view, Rel-17 introduces key performance indicators to
indicate the reliability/integrity of the measurement report
limited to the global navigation satellite system (GNSS)
positioning procedure.
Ultra-reliable, low-latency communication
URLLC has been a key enabler for the 5GS to enter various
verticals. Rel-15 established a solid foundation, and Rel-16
introduced further enhancements by the 3GPPs System
Architecture (SA) and RAN groups to better serve various
industry verticals such as factory automation, the transport
industry and electrical power distribution. These enhancements
included various user-plane redundancy schemes as well as
enhancements to improve reliability, reduce latency and support
time-sensitive communication (TSC).
The enhancements in Rel-17 aim to improve spectral efficiency
and system capacity, support URLLC in unlicensed spectrum
environments and strengthen the framework to support TSC. They
include Hybrid Automatic Repeat Request-Acknowledgement (HARQ-ACK)
enhancements, CSI enhancements, intra-UE multiplexing,
time-synchronization enhancements and service survival time as
an extension to TSC assistance information.
NR coverage
The direct impact that coverage has on service quality, opex and
capex makes it a key factor for both commercialization and
competition. In Rel-17, the 3GPP has identified the PUSCH as a
potential coverage bottleneck. To improve PUSCH coverage, the
3GPP is considering mechanisms for repetition and support for
transport block processing over multiple slots. Moreover, Rel-17
specifies mechanisms to support demodulation reference signal (DMRS)
bundling across PUSCH repetitions and signaling support for
dynamic PUCCH repetition factor indication.
Small data transmission
To support power-efficient connection establishment, the
existing NR RRC inactive mode enables a UE to resume a
previously established RRC connection. To further enhance the UE
power consumption at system access, Rel-17 specifies support for
data transmission in RRC inactive mode. Not having to resume an
RRC connection reduces the control plane signaling overhead,
which is especially relevant for low-power devices that support
traffic characterized by infrequent and small data
transmissions.
Non-public networks
In Rel-16, the 3GPP specified support for non-public networks (NPNs),
which provide access that is limited to a certain group of users
such as the devices belonging to a given factory. To provide
full support for industrial verticals, the 3GPP specified
support for two NPN deployment options. The first, known as
public-network-integrated NPNs, allows public operators to
support NPNs by associating them directly to their networks. The
second deployment option is known as standalone NPN (SNPN).
Broadly speaking, an SNPN has the same functionality and
characteristics as a regular public network.
The 3GPP provides further enhancements for SNPNs in Rel-17.
These enhancements include support for a UE accessing an SNPN
using external credentials (such as those from a public network
or those belonging to another SNPN), SNPN UE onboarding (to
provision the UE with new NPN credentials and/or subscription
parameters, for example) and support for emergency services.
Edge computing
Edge computing, which enables operator- and third-party services
to be hosted close to the UEs access point of attachment, was
supported in the initial 3GPP Rel-15 of 5GS. The baseline
architecture enables efficient service delivery by reducing
end-to-end latency and load on the transport network.
Rel-17 introduces mechanisms to discover edge application
servers. For example, it defines an Edge Application Server
Discovery Function (EASDF) primarily to support the session
breakout connectivity model. The EASDF acts as a Domain Name
System (DNS) resolver to the UE and can complement the DNS
queries with UE location-related information. This enables the
DNS system to resolve to application servers close to the UE
location.
Rel-17 also clarifies and enhances the use of UE route-selection
policy (URSP) rules for edge computing for the distributed
anchor and multiple Protocol Data Unit (PDU) session
connectivity models. The URSP rules configuration in the UE can
take specific application server information into account. This
in turn provides the UE with the ability to dynamically
establish PDU sessions for specific application servers,
eliminating the need to deploy support for complex session
breakout solutions.
Furthermore, Rel-17 defines enhanced support for the relocation
of the application server in case of UE mobility and includes
new mechanisms to expose QoS monitoring results.
Data networks analytics
Several architectural enhancements and newly defined types of
analytics in Rel-17 increase the scope and usability of network
data analytics. Support for the aggregation of analytics enables
use cases where a Network Data and Analytics Function (NWDAF) is
able to collect data and analytic reports from other localized
NWDAFs. The NWDAF has been disaggregated into two separate
logical entities, which enables multiple NWDAF (analytics
logical function) in the network to produce analytic reports
according to a model distributed from the NWDAF model training
logical function (MTLF).
Rel-17 also optimizes some procedures by including new network
functions (NFs) that make it possible to process data closer to
the data sources and enable lower signaling. The new data
collection coordination function enables a single collection of
data from 5G Core NFs, with the data being distributed by a
non-standardized message bus. The analytics data repository
function can store massive amounts of both data and analytic
reports. Rel-17 also enhances the input to analytic reports by
enabling the addition of information originating from UE
applications.
New features in 3GPP release 17
A key aspect of 5G NR is the continuous drive to support new
verticals and deployment scenarios. Rel-17 strengthens 5G
support for new use cases primarily through new development in
five areas: RedCap UE, non-terrestrial networks, frequency bands
beyond 52GHz, and the multicast and broadcast service (MBS).
Reduced-capability user equipment
To further widen the range of use cases for NR, Rel-17
introduces support for RedCap UE. RedCap UE will fulfill service
requirements somewhere in between the relaxed massive
machine-type communication (mMTC) requirements and highly
stringent URLLC requirements, as shown in Figure 3. RedCap UE
provides performance comparable to Rel-8 LTE UE but with
additional benefits such as improved latency and the capability
to operate in NR frequency bands ranging all the way up to
52GHz.
Figure 3: Rel-17
RedCap targets the requirement space between eMBB, mMTC and
URLLC
RedCap UEs
are significantly less complex than regular NR UEs. This is
thanks to a reduced number of radio receiver (RX) antenna
branches, reduced RX and radio transmitter (TX) bandwidth and
half-duplex operation, meaning that the UE is not required to
transmit and receive at the same time. The reduced complexity is
anticipated to result in a reduced device price point that will
support the use of NR in new applications such as industrial
sensor networks. The support of a single antenna branch will
facilitate more compact device form factors, which is critical
in popular wearable applications such as smart watches.
Non-terrestrial networks (NTN)
The NTN work in Rel-17 introduces new network topologies into
the 3GPP specifications. These topologies are based on
high-altitude platforms and low Earth orbit (LEO) and
geosynchronous orbit satellites. NTN complements terrestrial
networks with network coverage in remote areas over sea and land
where terrestrial coverage is absent. The work done by the 3GPP
addresses NR, Narrowband-Internet of Things (NB-IoT) and LTE for
Machine Type Communication (LTE-M), and it will thereby
facilitate 3GPP NTN-based MBB and massive IoT services from
Rel-17 onwards.
Rel-17 work builds on earlier studies performed in Rel-15 and
Rel-16, where NTN channel models and necessary adaptations of
the NR technology to support NTN were identified. The main
challenges identified in Rel-16 and addressed in Rel-17 are
related to the mobility and orbital height of the satellite. The
height causes a high path loss and a large RTT. The mobility of
an LEO satellite introduces a very high Doppler offset on the
radio link, and it also inevitably requires all devices to
frequently change their serving nodes. Rel-17 establishes basic
mechanisms to manage these challenges and provides a first set
of specifications to support NTNs based on NR, NB-IoT and LTE-M.
NR beyond 52.6GHz
Rel-16 supports operation in frequency range (FR) 1 and 2
covering the ranges 410MHz7.125GHz and 24.25GHz52.6GHz,
respectively. In Rel-17, FR2 is extended beyond 52.6GHz all the
way up to 71GHz using the existing NR downlink/uplink waveforms
with the purpose of encompassing new licensed and unlicensed
frequency bands in this range.
Operation in these bands does, however, affect several parts of
the NR radio. It impacts the signal phase noise characteristics,
the transmitter linearity, power efficiency and the receiver
noise figure, among other things. However, the 3GPP has
concluded that the use of new, advanced phase noise cancellation
algorithms will make the Rel-15 physical layer (that is, the
existing phase tracking reference signal and sub-carrier spacing
of 120kHz) sufficiently robust to support this frequency range.
Increased sub-carrier spacing of up to 960 kHz is still
specified to allow the 3GPP to exploit even wider carriers of up
to 2GHz and thereby unlock a new range of data rates.
Multicast and broadcast service
The MBS support in Rel-17 requires significantly less
operations, administration and maintenance effort than its 4G
predecessor, Evolved Multimedia Broadcast Multicast Service, as
well as improving resource efficiency. 5G MBS is primarily
intended to support important uses cases for public safety such
as mission-critical push-to-talk, as well as enabling features
like over-the-air software updates and live TV, video delivery
and IoT solutions.
The 5G QoS framework is also applicable to 5G MBS traffic. It
enables differentiated packet forwarding, which is crucial at
high traffic load in the context of applications in the public
safety domain.
Rel-17 also enables multicast sessions to UEs in RRC connected
state, as well as broadcast sessions to UEs in RRC connected,
inactive and idle states. The broadcast support for UEs in
inactive and idle states is important to support maximum
capacity for the broadcast service. Part of the feature is the
support for group scheduling, mobility for service continuity
and configurable feedback for reliability when needed.
Aside from those enhancements, to expedite the time to market,
the MBS is facilitated by features and functionality that have
already been specified. Implementation and configuration in a
way that is transparent to the UEs is expected to enable the
creation of single-frequency networks (SFNs).
3GPP release 18 introducing 5G Advanced
The 3GPP RAN standardization team began discussing the scope of
Rel-18 in June 2021 at the 3GPP RAN Rel-18 Workshop and aims for
approval of the detailed scope by December 2021. Of the more
than 500 proposals that were submitted to the workshop, Ericsson
has identified what we consider to be the most important
highlights and placed them in three categories.
Key enhancements for e-MBB use cases
Three of the most notable Rel-18 additions for eMBB use cases
are beamforming/MIMO, mobility enhancements and network power
savings.
Advanced antenna systems (AASs) are the main driver for
increasing spectral efficiency of wireless networks, and they
will continue to evolve due to factors such as enabling layer
1/layer 2 mobility, further improvements of uplink MIMO and
enhancements related to fixed-wireless access applications.
DSS is extremely useful when transiting from 4G to 5G and many
commercial networks already rely on it. To increase network
efficiency during that transition, further enhancements are
envisioned, such as improved NR performance when the number of
LTE UEs decreases gradually, and reduced impact on NR
performance due to interference from LTE broadcast signals.
Rel-18 also includes efforts to explore opportunities to further
reduce network energy consumption.
Key enhancements for non-eMBB use cases
The most notable enhancements for non-eMBB applications (such as
new or existing verticals) include RedCap, XR and national
security and public safety (NSPS).
RedCap UEs are expected to play a significant role in many
future applications. Based on Rel-17, Rel-18 RedCap solutions
will further reduce device cost and power consumption. Solutions
enabling energy harvesting, such as energy-efficient wake-up
radios, will be investigated.
In Rel-17, the 3GPP RAN standardization team is studying various
forms of augmented reality and virtual reality services and
assessing their performance when operating through 5G. The main
challenge is to simultaneously provide a very high data rate and
low/bounded latency. In Rel-18, the 3GPP RAN group will look
into traffic management for resource-efficient and low-latency
radio resource allocation, mobility support with consistent data
rates, UE energy-efficient operation compatible with XR traffic
and latency requirements.
Aside from automotive and industrial use cases, NSPS is the most
prominent new vertical using 5GS. RAN enhancements for the
remote control of drones and rogue drone detection are being
considered to improve the situational awareness of first
responders. Rel-18 will also further improve 5Gs support for
out-of-coverage scenarios by means of techniques such as
UE-to-UE relaying.
Cross-domain functionalities for both MBB and non-MBB use cases
We also want to highlight three cross-domain functionalities
that target both MBB and non-MBB use cases: AI/ML for physical
layer (PHY) enhancements, AI/ML for RAN enhancements, and full
duplex.
It is generally expected that AI/ML can significantly improve
PHY performance. The RAN standardization will therefore explore
the opportunities by setting up a general framework for
AI/ML-related PHY enhancements, including proper AI/ML modeling,
evaluation methodologies and performance requirements/testing. A
first area for concrete AI/ML enhancement could be on beam
management or channel estimation/prediction.
In Rel-17, one of the study items is to identify suitable use
cases and corresponding AI/ML-based solutions for RAN. In
Rel-18, enhancement for selective use cases from Rel-17 will be
taken into the normative phase that is, efficient traffic
steering and load balancing. The focus will be on enhancements
to current interfaces in the existing architecture. To
incentivize vendor competitiveness, one goal is to ensure that
AI models remain implementation-specific.
Despite the practical challenges and unclear performance
potential, there is a proposal to study the feasibility of full
duplex, where gNBs transmit and receive simultaneously on TDD
frequency bands. The study will investigate the achievable gains
and their dependency on cross-link interference and
self-interference mitigation.
Conclusion
3GPP release 17 builds on previous releases with the aim of
improving 5G System performance, supporting new use cases and
verticals, and providing ubiquitous connectivity in different
deployment conditions and scenarios. In the next phase, release
18 will create 5G Advanced, which will include new solutions and
technology components that continue to boost network performance
for mobile broadband and verticals.
5G Advanced will also introduce more intelligence into wireless
networks by including suitable machine-learning-based techniques
in different levels of the network. Future enhancements will
also cover a wide variety of new verticals and use cases powered
by artificial intelligence/machine learning technologies based
on a single platform. As the work progresses, we are committed
to ensuring that like 5G, 5G Advanced has the ability to support
all use cases from one system design, focusing on forward
compatibility and diverse configurability while ensuring maximum
simplicity (Ericsson).
5G evolution toward 5G advanced: An overview of 3GPP releases 17
and 18 (pdf)
Becoming 5G Advanced: The 3GPP 2025 Roadmap In Design
Becoming 5G Advanced: The 3GPP 2025 Roadmap
Becoming 5G Advanced: The 3GPP 2025 Roadmap(pptx)
The 3GPP and 5G
The 3GPP published the first versions of the 5G standard in
2018. The work and specifications are divided into three main
areas: System Architecture, Core and Terminal, and RAN. The 5G
RAN is also known as NR (New Radio) and is part of the 5th
Generation System.
The 3GPP organizes its work in releases with a continuous
numbering scheme. The first version of the 5G specifications
surfaced in 3GPP Rel-15 in 2018 and provided the base
functionality as well as a large set of optional features. In
subsequent releases, the 3GPP has added new functionality to the
existing baseline. This is done with backwards compatibility, so
that older terminals can still function in upgraded networks and
vice versa.
The 3GPP adds functionality that is required to satisfy
increasing demands on existing services (higher data rates for
mobile broadband, for example) or to satisfy requirements of new
services, use cases and deployment options (such as public
safety applications and relaying). However, features are
typically specified in a service- and use-case agnostic manner,
which means that it is up to vendors and operators to decide how
to use and combine the specified features.
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