1.
Ericsson 5G RAN System Techniques
STUDENT BOOK
LZT1381970 R1A
LZT1381970 R1A

2.
Ericsson 5G RAN System Techniques
- 2 - © Ericsson AB 2017 LZT1381970 R1A
DISCLAIMER
This book is a training document and contains simplifications.
Therefore, it must not be considered as a specification of the system.
The contents of this document are subject to revision without notice
due to ongoing progress in methodology, design and manufacturing.
Ericsson shall have no liability for any error or damage of any kind
resulting from the use of this document.
This document is not intended to replace the technical
documentation that was shipped with your system. Always refer to
that technical documentation during operation and maintenance.
© Ericsson AB 2017
This document was produced by Ericsson.
 The book is to be used for training purposes only and it is strictly
prohibited to copy, reproduce, disclose or distribute it in any manner
without the express written consent from Ericsson.
This Student Book, LZT1381970, R1A supports course number
LZU1082528.

3.
Table of Contents
LZT1381970 R1A © Ericsson AB 2017 - 3 -
Table of Contents
1 INTRODUCTION TO 5G..................................................................... 7
1 INTRODUCTION................................................................................8
1.1 ULTRA-FAST, ULTRA-HIGH CAPACITY, LOW-DELAY AND
FLEXIBLE ................................................................................................8
1.2 3GPP STANDARDIZATION..........................................................15
1.3 THE 5G SYSTEM (5GS)...............................................................27
1.3.1 3GPP DEFINITIONS..................................................................28
2 SUMMARY.......................................................................................31
2 ERICSSON 5G RAN ARCHITECTURE ........................................... 33
1 ERICSSON 5G RAN ARCHITECTURE...........................................34
1.1 SPLIT ARCHITECTURE ...............................................................37
1.2 ERICSSON CLOUD RAN .............................................................38
1.3 LTE/NR INTERWORKING ............................................................40
1.4 5G RAN ARCHITECTURE............................................................41
1.5 DEPLOYMENTS ...........................................................................42
1.6 LTE/NR INTEGRATION................................................................47
1.7 ARCHITECTURE SUMMARY.......................................................59
2 SUMMARY.......................................................................................59
3 INTRODUCTION TO NR .................................................................. 61
1 INTRODUCTION TO NR..................................................................62
1.1 RRC INACTIVE STATE ................................................................64
1.2 NR CELL .......................................................................................66
1.3 SYSTEM BROADCAST ................................................................70
1.4 CHANNEL STRUCTURE..............................................................73
1.4.1 DL REFERENCE AND SYNC SIGNALS ...................................75

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1.4.2 UL REFERENCE AND SYNC SIGNALS ...................................76
1.5 LAYER 2 FUNCTIONS..................................................................78
1.6 QUALITY OF SERVICE (QOS) WITH 5GC ..................................87
1.6.1 QOS MODEL GENERAL OVERVIEW.......................................87
1.6.2 5G QOS INDICATOR PARAMETERS.......................................96
1.6.3 REFLECTIVE QOS ....................................................................97
2 SUMMARY.......................................................................................98
4 NR LOWER LAYERS....................................................................... 99
1 NR LOWER LAYERS.....................................................................100
1.1 SLOTS, SUBFRAMES AND RADIO FRAMES ...........................103
1.2 MAC HARQ.................................................................................104
1.3 ULTRA-LEAN DESIGN ...............................................................107
1.4 NR PHYSICAL LAYER DESIGN.................................................109
1.5 FRAME STRUCTURE.................................................................124
1.6 CHANNEL CODING....................................................................134
1.7 SYNCHRONIZATION AND INITIAL ACCESS ............................139
1.8 DL CONTROL SIGNALING.........................................................142
1.9 REFERENCE SIGNALS..............................................................147
1.10 MASSIVE MIMO........................................................................154
1.11 MASSIVE MIMO/BEAMFORMING FOR 5G.............................163
1.12 RECIPROCITY CSI...................................................................169
1.13 CSI FEEDBACK........................................................................173
1.14 BEAMFORMING IMPLEMENTATION ......................................174
2 SUMMARY.....................................................................................177
5 MOBILITY AND MULTI-CONNECTIVITY...................................... 179
1 IDLE MODE MOBILITY..................................................................180
2 CONNECTED MODE MOBILITY...................................................185

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2.1 BEAM SHAPES AND BEAM SWEEPING ..................................196
2.2 SELF OPTIMIZING NETWORKS................................................201
3 MULTI CONNECTIVITY.................................................................202
3.1 DUAL CONNECTIVITY BETWEEN LTE AND NR......................204
4 SUMMARY.....................................................................................211
6 TABLE OF FIGURES ..................................................................... 213
7 ACRONYMS ................................................................................... 219

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Intentionally Blank

7.
Introduction to 5G
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1 Introduction to 5G
Objectives
Figure 1-1: Objectives
1 Give an overview of the concepts of 5G
1.1 Describe the 3GPP standardization for NR
1.2 Explain the overall 5G Architecture and terminology

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1 Introduction
5G standardization has, at the time of writing this document, just started (3GPP
Rel 14 and 15). This means that the content in this course is based partly on what
has been agreed in 3GPP so far, and partly on assumptions. Some details in this
textbook may change over time, as the 5G related standards continue to evolve.
Figure 1-2: What is 5G?
1.1 Ultra-fast, ultra-high capacity, low-delay and flexible
“5G” is normally associated with ultra-fast, ultra-high capacity, low delay and
flexible network architecture. 5G is also a lot about improved capacity, and app
coverage (improved speeds up to 1 Gbps out to the cell –edge).
The exponential rise in the mobile data traffic volumes that we have seen in the
recent years and the continuing increase in the upcoming years must be addressed
by the vendors and the operators.
To be able to meet the needs and requirements in the Networked Society, it is
obvious that the network performance needs to be increased.
Mobile and wireless communications Enablers for the Twenty-twenty
Information Society (METIS) project (5G project within EU) has defined the
requirements on 5G as displayed in the figure below.
› In general terms 5G is the new use cases (or refreshed old
ones) that can be carried over any suitable network.
– Radio access options: LTE, NR
– Core network options: EPC, NGCN
› NR: “5G New Radio” / “NR Radio Access” / “Next
Generation Radio”
› NGCN: “Next Generation Core Network” a.k.a. “5GC”: 5G
Core Network

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Figure 1-3: 5G requirements and use cases
The main objective of METIS was to respond to societal challenges beyond 2020
by providing the basis for the all-communicating world and lay the foundation for
a future radio access mobile and wireless communications system. This will
realize the METIS vision of a future where access to information and sharing of
data is available anywhere and anytime to anyone and anything.
METIS has developed a concept for the future 5G mobile wireless
communications system and has identified the research key building blocks of
such a future system.
The METIS overall technical goal provided a system concept that, relative to
2013, supports:
 1000 times higher mobile data volume per area
 10 times to 100 times higher number of connected devices
 10 times to 100 times higher typical user data rate
 10 years battery life for low power Massive Machine Communication
(MMC) devices
 5 times reduced End-to-End (E2E) latency
The key challenge is to achieve these objectives at a cost and energy consumption
similar to today’s networks.
Obviously, telecom vendors have to develop a 5G network that fulfills a lot of
demanding requirements. That network must be very flexible, high performing
and at the same time cost effective, as well as sustainable.
10-100X
End-user Data Rates
5X
Lower Latency
10-100X
Connected Devices
>10yr
Battery Life
1000X
Mobile Data Volumes
Secure
Sustainable
5G Requirements
Extreme & Diverse
Common Network
Dynamic & Secure
Network Slices
Mission Critical MTC Communications
<5ms E2E delay
99.999% transmission reliability
500 kmph relative velocity
Massive MTC
>10 years battery lifetime
>80% cost reduction
20dB better coverage

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Here, a brief history of the different cellular system generations is presented
below - from 1G to 5G, and their approximate release years.
Figure 1-4: History
The Multiple Access methods are also listed in the figure above.
For 1G and 2G, Frequency Division Multiple Access (FDMA) and Time Division
Multiple Access (TDMA) were used respectively.
For 3G, Wideband Code Division Multiple Access (WCDMA) was introduced.
Actually, CDMA was used already with IS-95 in 2G.
With LTE, Orthogonal Frequency Division Multiple Access (OFDMA) was
introduced, combining FDMA and TDMA with OFDM (Orthogonal Frequency
Division Multiplexing) as transmission scheme.
The figure above shows that 5G also uses OFDM and OFDMA and is specified
from 3GPP Release 14 and onwards. 5G aims to support a vast variety of use-
cases and, at the same time, be very high energy-efficient.
The history and evolution from a 3GPP perspective from 3G to 5G is shown in
the picture below. Note that 3GPP (despite its name) seldom defines generation
(3G, 4G etc).

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Introduction to 5G
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LTE specifications started with 3GPP Release 8. Enhancements are made in Rel
9-13. Rel 13 specifies LTE Advanced Pro.
The 5G work starts with Rel 14.
Figure 1-5: 3GPP Evolution
The new radio access technologies will be defined in the first place for the new
frequency bands. These access technologies are introduced to optimally support
ultra-high channel bandwidths in very high frequency bands above 6 GHz, as
well as lower bands down to below 1 GHz and to support advanced combination
of resources from different frequency bands. The technologies also support
efficient spectrum utilization for massive machine communication.

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Figure 1-6: 5G Radio Access
As stated previously, however, the LTE evolution will be backwards compatible
in respect to the billions of LTE terminals that will be on the market in 2020 and
migration of new access technologies to the LTE bands in operation in 2020 can
be done at a pace reflecting the terminal fleet at any time, quite similar to today’s
re-farming of the legacy GSM bands.
In the figure below, Ericsson’s product terminologies for 4G and 5G are
presented.
Figure 1-7: Radio Network Evolution
5G use cases are defined by different organizations, e.g. METIS, 3GPP and
NGMN. The Ericsson defined use cases are listed in the figure below.
MASSIVE IOT
CAT-M NB-IOT EXTENDED COVERAGE BATTERY LIFE TIME
5G CARRIER
5G ARCHITECTURE
INTERWORKING
5G NR
NR
MASSIVE MIMO
MULTI-USER MIMO
RAN VIRTUALIZATION
LATENCY REDUCTION
INTELLIGENT CONNECTIVITY
5G PLUG-INs
Road
to 5G
LTE FUNDAMENTALS
IOT
GIGABIT LTE
LEAN CARRIER
ELASTIC RAN
ADVANCED SERVICES
NETWORK MGMT
LTE EVOLUTION
4G

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Figure 1-8: 5G Use Cases
This screening below shows how the current LTE performance relates to the
required 5G performance, in terms of latency and cell edge bit rates for different
applications (use cases).
Figure 1-9: Application Screening Applications Requiring Specific 5G Radio
Access Capabilities
5G, however, is not only about supporting additional spectrum – it is also about
leveraging advanced technologies to obtain an even higher performance in terms
of bits per second achieved out of each deployed Hertz of spectrum.
5g
USE CASES
SMART VEHICLES,
TRANSPORT
BROADBAND AND MEDIA
EVERYWHERE
SENSOR NETWORKS
HUMAN MACHINE
INTERACTION
CRITICAL CONTROL
OF REMOTE DEVICES
CRITICAL SERVICES AND
INFRASTRUCTURE CONTROL

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The 2x2 MIMO technology introduced as standard in LTE, in which two
individual data streams are sent simultaneously in the same cell by two
independent antennas will evolve into massive MIMO-systems including up to
e.g. 32 antenna ports. Having a large number of antennas – which is more
practical in the higher frequencies – also allows for intelligent multi-dimensional
beam forming, where beams of power/sensitivity can be steered precisely in the
directions appropriate for the target device, while avoiding, as much as possible,
the directions which would result in interference to other co-scheduled devices.
Having a multitude of cells in operation in a limited physical area sets high
demand on coordination between the cells. Obviously, a further evolution of
Coordinated Multi-Point (CoMP) functionality will be an integral part of the
evolution towards 5G.
Equally important to remember is that the (planned) introduction of device-to-
device communication will be closely controlled by the network as well, to
minimize interference.
Figure 1-10: 5G Access – some key Technology areas
Certain network functions should be located close to the access to improve
certain characteristics (e.g., latency).
In the figure below:
 From a resource utilization point of view, push functions to the right
(i.e centralization in e.g. Primary Data Center)

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Introduction to 5G
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 From a transport and latency performance perspective, push to the left
(i.e. distribution to e.g. Access or even Base-station site).
Same principles also apply for the radio functions (PPF and RCF), which will be
described later in this course.
Figure 1-11: Network Slicing
1.2 3GPP standardization
The standardization of 5G is ongoing in ITU (International Telecommunication
Union) and 3GPP (Third Generation Partnership Project). For example, the radio
section of ITU, ITU-R, defines requirements that 3GPP will try to fulfill with its
specifications in the 38-series (Radio Technology beyond LTE).
In the figure below, interpretations of the arrows between ITU and 3GPP:
 the ITU workshop 2017 creates Requirements
 the 3GPP Study Item will create Concepts
 the NR ph 2 will create Specifications
NGMN milestones are included as reference/proof that the ITU and 3GPP
activities are in line with the operator’s expectations/needs.
Other milestones are the Olympic winter games in PyeongChang 2018 and
summer games in Tokyo 2020, when both trial and (pre-)commercial systems are
planned to be launched.
The ITU requirements IMT2020 will most likely be fulfilled by 3GPP
specifications and approved as IMT2020 specifications.

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Figure 1-12: 5G standardisation timeplan
A major decision was taken in March 2017 in RAN on the 5G New Radio (NR)
workplan. In particular, the group agreed to have an intermediate milestone for
the early completion of the Non-standalone (NSA) 5G NR mode for the enhanced
Mobile BroadBand (eMBB) use-case. In Non-standalone mode the connection is
anchored in LTE while 5G NR carriers are used to boost data-rates and reduce
latency.

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Introduction to 5G
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Figure 1-13: 3GPP NR Workplan
With the updated work plan, NSA will be finalized by March 2018.
At the same time, the group re-instated its commitment to complete the
Standalone (SA) 5G NR mode by September 2018 and put in place a plan to
achieve that.
The two phases of NR are summarized in the below picture. Most of the concepts
listed (at least for phase 1) are described later in this course.

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Figure 1-14: NR Phase 1 and 2
First step includes a subset of use cases & requirements and should be forward-
compatible with use cases & requirements added in a later phase.
The “Road to 5G” includes 3GPP release 13 and 14. A summary of the current
3GPP Rel 13 is shown in the below picture.
Figure 1-15: LTE Rel-13
Phase 1 – early
commercial deployments
› Focus on MBB and URLLC
› UMa / UMi, O2I, up to ~500m ISD
› Frequency range up to 52.6 GHz
– 3.5, 28 GHz
– 39 GHz (US), 4.4 GHz (Asia)
› FDD and Dynamic TDD
› Standalone
– LTE-NR Dual Connectivity
– NR-NR Carrier Aggregation
› NR-LTE Co-channel Co-existence
(DL & UL)
› OFDM, Mini-slots, RRC Inactive
› NW Slicing
Phase 2 – Full IMT2020
compliance
› Unlicensed spectrum
– Standalone and license assisted
– 5, 3.5 and 60GHz
› Multiple access
› Lower layer CU/DU split
› Non-terrestrial Networks
› eV2V evaluation
› Integrated Access Backhaul
14

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Introduction to 5G
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As an example, in Rel 13, MIMO enhancements include:
 Full flexible array handling
o FD-MIMO, Elevation BF
 Up to 16 antenna ports
 Beamformed CSI-RS
o Targeting different scenarios in complement to non-
bemformed CSI-RS.
 SRS enhancements for small cells
o Higher SRS capacity
 DMRS enhancements
o More co-scheduled UEs using 4 bit port indication
A summary of the ongoing topics in 3GPP Rel 14 is shown in the figure below.
Figure 1-16: LTE Rel-14
Further Rel-14 Work Items/Study Items
 SRS switching (minor TDD enhancement)
 MUST (no gain identified in reasonable scenarios)
 SI eCoMP
 SI VoLTE (minor optimization)

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 SI on wearables (part of MTC)
 SIs in RAN3
 SI on flexible BW
3GPP Release 15 is currently being developed and the figure below shows some
of the early specifications in the 38-series.
Figure 1-17: 3GPP 38-series - Radio technology beyond LTE
Below is a summary of the 3GPP requirements on 5G.
http://www.3gpp.org/DynaReport/38-series.htm
TS 38.101NR; User Equipment (UE) radio transmission and
reception
TS 38.104NR; Base Station (BS) radio transmission and
reception
TS 38.133NR; Requirements for support of radio resource
management
TS 38.141NR; Base Station (BS) conformance testing
TS 38.201NR; Physical layer; General description
TS 38.202NR; Physical layer services provided by the physical
layer
TS 38.211NR; Physical channels and modulation
TS 38.212NR; Multiplexing and channel coding
TS 38.215NR; Physical layer measurements
TS 38.300NR; Overall description; Stage-2
TS 38.304NR; User Equipment (UE) procedures in idle mode
TS 38.306NR; User Equipment (UE) radio access capabilities
TS 38.307NR; Requirements on User Equipments (UEs)
supporting a release-independent frequency band
TS 38.321NR; Medium Access Control (MAC) protocol
specification
TS 38.322NR; Radio Link Control (RLC) protocol specification
TS 38.323NR; Packet Data Convergence Protocol (PDCP)
specification
TS 38.331NR; Radio Resource Control (RRC); Protocol
specification
TS 38.401NR-RAN; Architecture description
TS 38.410NG-RAN; NG general aspects and principles
TS 38.411NR-RAN; NG layer 1
TS 38.412NR-RAN; NG signalling transport
TS 38.413NR-RAN; NG Application Protocol (NGAP)
TS 38.414NR-RAN; NG data transport
TS 38.420NR-RAN; Xn general aspects and principles
TS 38.421 NR-RAN; Xn layer 1
TS 38.422 NR-RAN; Xn signalling transport
TS 38.423 NR-RAN; Xn Application Protocol (XnAP)
TS 38.424 NR-RAN; Xn data transport
TS 38.425 NR-RAN; Xn interface user plane protocol
TR 38.801 Study on new radio access technology: Radio access
architecture and interfaces
TR 38.802 Study on new radio access technology Physical layer
aspects
TR 38.803 Study on new radio access technology: Radio
Frequency (RF) and co-existence aspects
TR 38.804 Study on new radio access technology Radio interface
protocol aspects
TR 38.805 Study on new radio access technology; 60 GHz
unlicensed spectrum
TR 38.810 Study on test methods for New Radio
TR 38.811 Study on NR to support non-terrestrial networks
TR 38.812 Study on Non-Orthogonal Multiple Access (NOMA) for
NR
TR 38.874 NR; Study on integrated access and backhaul
TR 38.889 Study on NR-based access to unlicensed spectrum
TR 38.900 Study on channel model for frequency spectrum above
6 GHz
TR 38.901 Study on channel model for frequencies from 0.5 to 100
GHz
TR 38.912 Study on new radio access technology
TR 38.913 Study on scenarios and requirements for next
generation access technologies
Note: 38.213 split into Phy Layer Proc 213 (Control) & 214 (data)

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Figure 1-18: General 5G Requirements in 3GPP
The 3GPP specification 38.913 is a study on scenarios and requirements for
“5G”.
The focus is on the three use case families:
 Enhanced Mobile Broadband (eMBB)
 Massive Machine Type Communications (mMTC)
 Ultra-reliable and Low Latency Communications (URLLC)
Figure 1-19: Study on scenarios and requirements for Next Generation Access
Technologies
Examples of key performance indicators are shown in Figure 1-20.
› The families of usage scenarios for IMT for 2020 and beyond include:
› - eMBB (enhanced Mobile Broadband)
› - mMTC (massive Machine Type Communications)
› - URLLC (Ultra-Reliable and Low Latency Communications)
http://www.3gpp.org/ftp/specs/archive/38_series/38.913/

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Figure 1-20: Key Performance Indicators -examples
Reliability can be evaluated by the success probability of transmitting X bytes
within a certain delay, which is the time it takes to deliver a small data packet
from the radio protocol layer 2/3 SDU ingress point to the radio protocol layer
2/3 SDU egress point of the radio interface, at a certain channel quality (e.g.,
coverage-edge).
A general URLLC reliability requirement for one transmission of a packet is 1-
10-5
(0.99999) for 32 bytes with a user plane latency of 1ms.
More 3GPP KPIs are described below.
Coverage
"Maximum coupling loss" (MaxCL) in uplink and downlink between device and
Base Station site (antenna connector(s)) for a data rate of 160 bps, where the data
rate is observed at the egress/ingress point of the radio protocol stack in uplink
and downlink.
The target for coverage should be 164dB.
Extreme Coverage
Maximum coupling loss” to device from Base Station site to deliver successfully
voice services, Data services (up to 2Mbps for stationary services and up 384kbps
for moving devices) and all necessary control channels in UL and DL for a UE
assuming a propagation distance of 100km.
[To be defined for Long Distance communication]
› Peak data rate
– The target for peak data rate should be 20 Gbps for downlink and 10 Gbps for uplink.
› Peak Spectral efficiency
– The target for peak spectral efficiency should be 30 bps/Hz for downlink and 15 bps/Hz for uplink.
› Bandwidth
– This is an ITU-R requirement from IMT-2020. It may not be up to 3GPP to set a value for this requirement.
› Control plane latency
– The target for control plane latency should be 10ms.
› User plane latency
– For URLLC, 0.5 ms for UL, and 0.5 ms for DL. For eMBB, 4 ms for UL, and 4 ms for DL.
› Mobility interruption time
– The target for mobility interruption time should be 0ms.
› Inter-system mobility
– Inter-system mobility refers to the ability to support mobility between the IMT-2020 system and at least one IMT
system.
› Reliability
– The target for reliability should be 1-10-5 within 1ms.
TR 38.913 v14.1.0

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The 3GPP system should support the following deployment scenarios in terms of
very large cell range:
 up to 100 km: with the performance targets defined in section
 up to 200 km: slight degradations in the achieved performance is
acceptable.
 up to 400 km: should not be precluded by the specifications.
UE battery life
UE battery life can be evaluated by the battery life of the UE without recharge.
For mMTC, UE battery life in extreme coverage shall be based on the activity of
mobile originated data transfer consisting of [TBD bytes] UL per day followed
by [TBD bytes] DL from MCL of [TBD] dB, assuming a stored energy capacity
of [TBD].
The target for UE battery life should be 15 years.
UE energy efficiency
UE energy efficiency means the capability of a UE to sustain much better mobile
broadband data rate while minimizing the UE modem energy consumption.
Cell/Transmission Point/TRP spectral efficiency
TRP spectral efficiency is defined as the aggregate throughput of all users (the
number of correctly received bits, i.e. the number of bits contained in the service
data units (SDUs) delivered to Layer 3, over a certain period of time) divided by
the channel bandwidth divided by the number of TRPs. A 3 sector site consists of
3 TRPs. In case of multiple discontinuous "carriers" (one carrier refers to a
continuous block of spectrum), this KPI should be calculated per carrier. In this
case, the aggregate throughput, channel bandwidth, and the number of TRPs on
the specific carrier are employed.
NOTE: 3GPP should strive to meet the target with typical antenna configuration
Quantitative KPI NOTE2
[NOTE2 The target considered as a starting point for eMBB deployment
scenarios is in the order of 3 times IMT-Advanced requirements for full buffer.]
Area traffic capacity
Area traffic capacity means total traffic throughput served per geographic area (in
Mbit/s/m2
). This metric can be evaluated by two different traffic models: Full
buffer model and Non full buffer model
 By full buffer model: Total traffic throughput served per geographic
area (in Mbit/s/m2
). The computation of this metric is based on full
buffer traffic.
 By non-full buffer model: Total traffic throughput served per
geographic area (in Mbit/s/m2
). Both the user experienced data rate

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and the area traffic capacity need to be evaluated at the same time
using the same traffic model.
The area traffic capacity is a measure of how much traffic a network can carry
per unit area. It depends on site density, bandwidth and spectrum efficiency. In
the special case of a single layer single band system, it may be expressed as:
area capacity (bps/m2
) = site density (site/m2
) × bandwidth (Hz) × spectrum
efficiency (bps/Hz/site)
NOTE: Results of TRP spectral efficiency for non-full buffer are also provided
separately.
In order to improve area traffic capacity, 3GPP can develop standards with means
for high spectrum efficiency. To this end, spectrum efficiency gains in the order
of three times IMT-Advanced are targeted. Furthermore, 3GPP can develop
standards with means for large bandwidth support. To this end, it is proposed that
at least 1GHz aggregated bandwidth shall be supported.
The available bandwidth and site density [NOTE: ‘site’ here refers to single
transmission and reception point (TRP)], which both have a direct impact on the
available area capacity, are however not under control of 3GPP.
Based on this, it is proposed to use the spectrum efficiency results together with
assumptions on available bandwidth and site density in order to derive a
quantitative area traffic capacity KPI for information.
User experienced data rate
User experienced data rate [NOTE: Non-full buffer simulations are preferred for
the evaluation of this KPI.] can be evaluated for non-full buffer traffic and for full
buffer traffic.
For non-full buffer traffic, user experienced data rate is the 5%-percentile (5%) of
the user throughput. User throughput (during active time) is defined as the size of
a burst divided by the time between the arrival of the first packet of a burst and
the reception of the last packet of the burst.
The target values for the user experienced data rate are associated with non-full
buffer evaluation. The non-full buffer user experienced data rate target is
applicable at the non-full buffer area traffic capacity traffic level.
For full buffer traffic, user experienced data rate is calculated as:
user experienced data rate = 5% user spectrum efficiency × bandwidth
Here it should be noted that the 5% user spectrum efficiency depends on the
number of active users sharing the channel (assumed to be 10 in the ITU
evaluations), and that the 5% user spectrum efficiency for a fixed transmit power
may vary with bandwidth. To keep a high 5% user spectrum efficiency and a few
users sharing the channel, a dense network is beneficial, i.e. 5% user spectrum
efficiency may vary also with site density. [‘Site’ here refers to single
transmission and reception point (TRP).]

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To improve user experienced data rates, 3GPP can develop standards with means
for high 5% user spectrum efficiency. To this end, 5% user spectrum efficiency
gains in the order of three times IMT-Advanced are proposed. Furthermore,
3GPP can develop standards with means for large bandwidth support. To this
end, it is proposed that at least 1GHz aggregated bandwidth shall be supported.
The available bandwidth and site density, which both have a strong impact on the
available user experienced data rates, are however not under control of 3GPP.
Based on this, the full buffer experienced user data rate is evaluated for
information without numerical requirements.
5th percentile user spectrum efficiency
5th percentile user spectrum efficiency means the 5% point of the cumulative
distribution function (CDF) of the normalized user throughput. The (normalized)
user throughput is defined as the average user throughput (the number of
correctly received bits by users, i.e., the number of bits contained in the SDU
delivered to Layer 3, over a certain period of time, divided by the channel
bandwidth and is measured in bit/s/Hz. The channel bandwidth for this purpose is
defined as the effective bandwidth times the frequency reuse factor, where the
effective bandwidth is the operating bandwidth normalized appropriately
considering the uplink/downlink ratio. In case of multiple discontinuous
“carriers” (one carrier refers to a continuous block of spectrum), this KPI should
be calculated per carrier. In this case, the user throughput and channel bandwidth
on the specific carrier are employed.
Quantitative KPI
[NOTE: The target considered as a starting point for eMBB deployment scenarios
is in the order of 3x IMT-Advanced requirements for full buffer]
Connection density
Connection density refers to total number of devices fulfilling specific QoS per
unit area (per km2
). QoS definition should take into account the amount of data or
access request generated within a time t_gen that can be sent or received within a
given time, t_sendrx, with x% probability.
The target for connection density should be 1 000 000 device/km2
in urban
environment.
3GPP should develop standards with means of high connection efficiency
(measured as supported number of devices per TRP per unit frequency resource)
to achieve the desired connection density.
Mobility
Mobility means the maximum user speed at which a defined QoS can be achieved
(in km/h).
The target for mobility target should be 500km/h.

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Network energy efficiency
The capability is to minimize the RAN energy consumption while providing a
much better area traffic capacity.
Qualitative KPI as baseline and quantitative KPI is FFS.
Editor’s notes: Inspection is the baseline method to qualitatively check the
capability of the RAN to improve area traffic capacity with minimum RAN
energy consumption, e.g., ensure no or limited increase of BS power with more
antenna elements and larger bandwidth, etc. As qualitative evaluation, 3GPP
should ensure that the new RAT is based on energy efficient design principles.
When quantitative evaluation is adopted, one can compare the quantity of
information bits transmitted to/received from users, divided by the energy
consumption of RAN.

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1.3 The 5G System (5GS)
3GPP has defined the terminology for 5G. 5G System (5GS) is the 5G Core
(5GC), the 5G RAN and the UE.
Figure 1-21: 3GPP 5G System (5GS) -5G Core network and 5G-(R)AN
5G System consists of the following functions and networks:
 Authentication Server Function (AUSF)
 Core Access and Mobility Management Function (AMF)
 Data network (DN), e.g. operator services, Internet access or 3rd party
services
 Structured Data Storage network function (SDSF)
 Unstructured Data Storage network function (UDSF)
 Network Exposure Function (NEF)
 NF Repository Function (NRF)
 Policy Control function (PCF)
 Session Management Function (SMF)
 Unified Data Management (UDM)
 User plane Function (UPF)
 Application Function (AF)
 User Equipment (UE)
 (Radio) Access Network ((R)AN)

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1.3.1 3GPP Definitions
For the purposes of the present document, the terms and definitions 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.
 5G Access Network: An access network comprising a 5G-RAN
and/or non-3GPP AN connecting to a 5G Core Network.
 5G Core Network: The core network specified in the present
document. It connects to a 5G Access Network.
 5G QoS Flow: The finest granularity for QoS forwarding treatment in
the 5G System. All traffic mapped to the same 5G QoS Flow receive
the same forwarding treatment (e.g. scheduling policy, queue
management policy, rate shaping policy, RLC configuration, etc.).
Providing different QoS forwarding treatment requires separate 5G
QoS Flow.
 5G QoS Indicator: A scalar that is used as a reference to a specific
QoS forwarding behaviour (e.g. packet loss rate, packet delay budget)
to be provided to a 5G QoS Flow. This may be implemented in the
access network by the 5QI referencing node specific parameters that
control the QoS forwarding treatment (e.g. scheduling weights,
admission thresholds, queue management thresholds, link layer
protocol configuration, etc.).
 5G-RAN: A radio access network that supports one or more of the
following options with the common characteristics that it connects to
5GC:
o Standalone New Radio.
o New Radio is the anchor with E-UTRA extensions.
o Standalone E-UTRA.
o E-UTRA is the anchor with New Radio extensions.
 Editor's note: The definition will be revisited after
RAN decision on 5G-RAN.
 5G System: 3GPP system consisting of 5G Access Network (AN), 5G
Core Network and UE.
 Allowed NSSAI: an NSSAI provided by the serving PLMN during
e.g. a registration procedure, indicating the NSSAI allowed by the
network for the UE in the serving PLMN for the current registration
area.
 Allowed area: Area where the UE is allowed to initiate
communication.
 Configured NSSAI: an NSSAI that has been provisioned in the UE.

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 DN Access Identifier (DNAI): For a DNN, Identifier of a user plane
access to the DN.
 Forbidden area: An area where the UE is not allowed to initiate
communication.
 Initial Registration: UE registration in RM-DEREGISTERED state.
 Local Area Data Network: a DN that is accessible by the UE only in
specific locations, that provides connectivity to a specific DNN, and
whose availability is provided to the UE.
 Mobility pattern: Network concept of determining within an NF the
UE mobility parameters.
 Mobility Registration update: UE re-registration when entering new
TA outside the TAI List.
 Network Function: A 3GPP adopted or 3GPP defined processing
function in a network, which has defined functional behaviour and
3GPP defined interfaces.
NOTE: A network function can be implemented either as a network
element on a dedicated hardware, as a software instance running on a
dedicated hardware, or as a virtualised function instantiated on an
appropriate platform, e.g. on a cloud infrastructure.
 Network Slice: A logical network that provides specific network
capabilities and network characteristics.
 Network Slice instance: A set of Network Function instances and the
required resources (e.g. compute, storage and networking resources)
which form a deployed Network Slice.
 NF service: a functionality exposed by a NF through a service based
interface and consumed by other authorized NFs.
 NF service operation: An elementary unit a NF service is composed
of.
 Non-allowed area: Area where the UE is allowed to initiate
registration procedure but no other communication.
 Non-seamless Non-3GPP offload: The offload of user plane traffic
via non-3GPP access without traversing either N3IWF or UPF.
 NSSAI: Network Slice Selection Assistance Information
 PDU Connectivity Service: A service that provides exchange of
PDUs between a UE and a Data Network.
 PDU Session: Association between the UE and a Data Network that
provides a PDU connectivity service. The type of association can be
IP, Ethernet or unstructured.
 Periodic Registration update: UE re-registration at expiry of
periodic registration timer.
 Requested NSSAI: the NSSAI that the UE may provide to the
network.

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 Service based interface: It represents how the set of services
provided/exposed by a given NF.
 Service Continuity: The uninterrupted user experience of a service,
including the cases where the IP address and/or anchoring point
change.
 Session Continuity: The continuity of a PDU session. For PDU
session of IP type "session continuity" implies that the IP address is
preserved for the lifetime of the PDU session.
 Uplink Classifier: UPF functionality that aims at diverting Uplink
traffic, based on filter rules provided by SMF, towards Data Network.
The 5G System Architecture contains the following reference points:
 N1: Reference point between the UE and the AMF.
 N2: Reference point between the (R)AN and the AMF.
 N3: Reference point between the (R)AN and the UPF.
 N4: Reference point between the SMF and the UPF.
 N5: Reference point between the PCF and an AF.
 N6: Reference point between the UPF and a Data Network.
NOTE: The traffic forwarding details of N6 between a UPF acting as
an uplink classifier and a local data network will not be specified in
this release.
 N7: Reference point between the SMF and the PCF.
 N7r: Reference point between the PCF in the visited network and
the PCF in the home network.
 N8: Reference point between the UDM and the AMF.
 N9: Reference point between two Core UPFs.
 N10: Reference point between the UDM and the SMF.
 N11: Reference point between the AMF and the SMF.
 N12: Reference point between AMF and AUSF.
 N13: Reference point between the UDM and Authentication
Server function the AUSF.
 N14: Reference point between two AMFs.
 N15: Reference point between the PCF and the AMF in case of
non-roaming scenario, PCF in the visited network and AMF in case of
roaming scenario.

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 N16: Reference point between two SMFs, (in roaming case
between SMF in the visited network and the SMF in the home
network).
 N17: Reference point between AMF and EIR.
 N18: Reference point between any NF and UDSF.
 N19: Reference point between NEF and SDSF.
2 Summary
Figure 1-22: Chapter 1 Summary
1 Give an overview of the concepts of 5G
1.1 Describe the 3GPP standardization for NR
1.2 Explain the overall 5G Architecture and terminology

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Intentionally Blank

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2 Ericsson 5G RAN Architecture
Objectives
Figure 2-1: Objectives
2 Explain Ericsson’s view on the 5G RAN Architecture
2.1 Describe nodes and interfaces
2.2 Describe the Dual Connectivity architecture and options

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1 Ericsson 5G RAN Architecture
The current RAN / CN split (S1-based) is working well and should be considered
as a starting point.
Figure 2-2: 5G Architecture -Common CN/RAN interface
The CN is an evolution of the EPC supporting new 5G functions and also a new
core network (NextGen Core or 5G Core, 5GC).
The 5G RAN-CN interface should be based on legacy S1 to reuse basic
functions/procedures (when possible).
A new 5G RAN-CN (NG2, NG3) interface based on S1 does not prevent non-
backwards development of both RAN and CN.
Before going into the 5G RAN architecture, let us have a look at the overall
architecture, including 5G Core (5GC). The 5G networks deployments will, in
many cases, start with 5G RAN (NR) connected to a 5G enabled EPC. Later, or
in certain initial deployments we may see 5G RAN connected to 5GC (or
“NextGen Core” as it previously has been referred to).
Mobility between NR/LTE can be handled without CN assistance
NR
standalone
LTE
standalone
eX2
NR /
LTE co-located
eX2 eX2
EPC / NextGen Core (5GC)
eS1-C, U / N2, N3
eS1-C, U / N2,N3 eS1-C, U / N2, N3
› eLTE eNB
– evolution of eNB that supports
connectivity to EPC and NextGen
Core
› gNB
– NR node
› NextGen Core (5GC)
– Core Network for Next Generation
System
› N2, N3
– The CP and UP interface between a
gNB and a NextGen Core,
respectively
› TR(x)P
– Transmission and Reception Point
– The antenna panel(s) used by gNB
eNB
gNB
G-UTRAN E-UTRAN

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Figure below shows the high level 5G Core Architecture functional view - as of
end of March 2017.
Figure 2-3: 5G CORE architecture overview Functional view – p2p reference
representation, non-roaming
Access and Mobility Management Function
 Termination point for RAN CP i/f incl NAS (NG1/NG2) transport
 UE Authentication & Access security
 Mobility management (Reachability, Idle/Active Mode mobility MM
state handling)
 SMF selection
 NAS signaling:
o NAS Ciphering and Integrity protection
o Termination of MM NAS
o Forwarding of SM NAS
 N2 signaling:
o Sending/reveiving MM information to the (R)AN, i.e. MM
specific N2 information
o Forwarding of N2 SM info (e.g. QoS)

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Session Management Function
 NAS handling for SM
 Sending QoS/policy N2 information to the AN via AMF
 Idle/Active aware
 UE IP address allocation & management
 Policy & Offline/Online Charging i/f termination
 Policy enforcement control part
 Lawful intercept (CP and interface to LI System)
 UP selection and termination of N4 interface
User Plane Function
 Anchor point for Intra-/Inter-RAT mobility (when applicable)
 External IP point of interconnect
 Packet routing & forwarding
 QoS handling for User plane
 Packet inspection and PCC rule enforcement
 Lawful intercept (UP collection)
 Roaming interface (UP)
 Traffic counting and reporting
Unified Data Management will have similar functionality as the HSS in the Rel-
14 EPC.
AUSF contains mainly the EAP Authentication server functionality
Policy Control functions is expected to have similarities with the existing Policy
framework and with addition of standardized Mobility based policies and a
standardised interface to AMF
NG RAN includes the NR and LTE radio technologies.
Note: The CN-RAN functional split is assumed to be the same/similar as for
EPC-LTE and the N2/N3 are assumed evolutions of S1-MME and S1-U (but
using new 3GPP specifications)
On SMF selection - key principles include:
 A UE with multiple established PDU sessions may be served by
different instances of SMF.
 The AMF selects the SMFs for the PDU sessions.

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o AMF may select different SMF functions for different PDU
sessions.
o In particular, in case of a UE connected to multiple slices
there can be different instances of SMF serving the UE in the
different slices
o AMF selects SMF based on Data Network Name, slice
information, subscription data etc.
o In case of home-routed roaming, AMF selects a vSMF in
VPLMN and a hSMF in HPLMN to serve the PDU Session
 SMSF, NEF and NRF functions are not included in this representation,
as the discussion mainly focus on the other functions so far
Flexible deployment of CN functions (running as VNFs) makes it possible to
meet 5G use case requirements (low latency, high network load, standalone).
Deployment can be different for different use cases.
Common RRC / PDCP for NR and LTE makes it possible to support Dual
Connectivity and other tight integration features, allowing seamless mobility,
resource pooling etc. across the RATs or frequency/cell layers.
Centralization of MeNB (Master eNB) functions can be considered as a
deployment option (should be compared to the DC principle where the MeNB is
just a role).
It is also beneficial to support initial access through any layer.
1.1 Split Architecture
CP/UP split of PDCP make sense in the products since the PDCP-U carries so
much more traffic than PDCP-C. By separating control plane and user-plane, we
can let them scale independently with their respective loads. This is required to
cover the vast variety of 5G use case requirements (e.g. Critical MTC, Massive
MTC etc).
Current assumption is that the NR protocol on a high level is similar to that of
LTE, and that it is possible to split between the PDCP and RLC entity.

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Figure 2-4: Ericsson architecture assumptions - Split Architecture
There is also a split between upper layer 2 (PDCP and RRC) and lower layer 2
(RLC and MAC), with the interface C5 in between. This will be described in
further detail later in this course.
A third split can be described as the separation of the physical layer in different
entities; parts of baseband (e.g. beamforming function) is placed in the RRU
(AIR) while other baseband functions reside in the BPU (Base band Processing
Unit). They are separated by the C2 interface. This is not shown in the picture,
but will be described later in the course.
1.2 Ericsson Cloud RAN
Figure 2-5: RAN transport Architecture A Flexible Architecture supporting many
options
Antenna
elements RF
(evolved)
X2
(evolved)
S1
RLC
MAC
PHY
PDCP-U
Antenna
elements RF
RLC
MAC
PHY
LTE
NR
(evolved)
RRC
CN UP
CN CP
To other
Base Stations
RAN/CN logical split is
kept as a starting point
Common PDCP and evolved
RRC for NR and LTE
PDCP
-C
The NR radio interface protocol stack should support separation of RLC from
PDCP, as well as separation of RRC and PDCP-U
Logical
architecture
Common Core
for NR and LTE
Virtualization of Aggregated
CN and RAN function
› Distributed RAN
› Centralized RAN
› Virtualized RAN
› Elastic RAN
L3
L2 high
L2 low
L1
L3
L2
L1
L3
L2
L1
L3
L2
L1
(e)S1
(e)S
1
(e)X2
(e)X
2
(e)S1
(e)S
1
E5
(e)CPRI
C5
5

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Cloud RAN includes more than just centralization and virtualization. Without
concepts such as D-RAN, C-RAN and Coordination in the portfolio, it would risk
building topologies and architectures that could negatively impact previous
infrastructure investments and result in lower performance. Anything that is
offered to handle the asymmetries in coverage and throughput (such as e.g. Dual
Connectivity optimized architectures) must blend nicely with what has been done
in the past, is being done now and what Ericsson will do in near future. The
PDCP-RLC and the PHY splits will allow these asymmetries to be handled, while
leveraging on existing lower bands and RATs as coverage anchors in a seamless
fashion. New commercial compute platform and virtualization mechanism will
add operational and transport network optimization benefits for certain
deployments (e.g. non-co-located frequency deployment grids). Centralized
common baseband, maybe for certain hotspots such as stadiums, can also be used
in conjunction with the new topology as can the fully distributed approach with
X2 and tight X2 collaboration and coordination. E-RAN can be added to tie any
of these aspects together perfectly for the best possible coordination gains, when
possible (from a transport perspective) and necessary (from a spectral efficiency
or an end user performance perspective).
The separated and centralized higher layers. although small in absolute terms, can
benefit from additional pooling gains by increased aggregation, once a split
architecture (V-RAN) has been decided on. Pooling gains for the higher layers
(PDCP and RRC), although small in absolute terms today, may well increase
with tomorrows much higher peak rates for 5G and much greater context storage
requirements for tomorrow’s massive IOT scenarios.
Centralizing the higher layers of the eNodeB and placing them on a virtualized
execution platform will facilitate running RAN functionality in close proximity to
core and other applications. This may provide additional options in the future, for
example, real time critical applications (or Mobile Edge Computing type
scenarios, e.g. media caching).
Cloud RAN is not only centralization (C-RAN) and virtualization (vRAN) or any
single one of the other RAN components such as D-RAN and E-RAN. Cloud
RAN is a way of looking at RAN more as a set of shared resources that
collaboratively presents itself as one cohesive entity to the outside world. This
results in previously unparalleled flexibility. The Cloud RAN encompasses
everything from distributed functionality, distributed computing and processing
that’s interconnected in a collaborative way as well of centralization of certain
resources, sometimes for increased coordination possibilities but also for pooling
gains and various degrees of inter-layer cooperation (e.g. tighter collaboration
RAN-Core-Applications, etc.).
CPRI is not scalable as it grows linearly with the number of antennas times the
bandwidth, both expected to increase substantially in the future.
The main virtue of centralizing L2 user plane (i.e. PDCP) is to avoid transport
network trombone effects and to provide faster and more robust mobility across
frequencies and RATs.
The centralized L3 will require a very low latency but only based on application
requirements and not as stringent as CPRI.

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X2 interface is still applicable between all nodes not connected with E-RAN for
orderless and seamless network operation.
L3 control plane can be fully placed in the cloud.
Many aspect of the new RAT (NR) that drives a different functional split has
nothing to do with the NR as such.
Instead they are driven by the fact that NR in practice will be:
 used as a much wider carrier
o hence much greater bitrates (throughput asymmetry)
 deployed on a much higher frequency band
o hence may use massive MIMO/Beamforming
 will have limited coverage
o hence will be deployed on a denser site grid, on sites where
the lower frequencies are not needed and consequently not
deployed (coverage asymmetry)
1.3 LTE/NR Interworking
The interworking between NR and LTE is very important. It is expected to give
very high gains in coverage and capacity, as can be seen in the graph below.
Figure 2-6: LTE/NR Interworking

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We see in the graph that LTE or NR alone does not perform very well for the
worst 5% connections, but with interworking between the two systems, the
performance becomes very good. The explanation is that NR at higher frequency
bands has relatively bad coverage, but its high capacity will offload LTE, so LTE
can cover the connections with worst quality, e.g cell-edge users.
1.4 5G RAN Architecture
In Figure 2-7, Ericsson RAN Architecture is shown. We see different
implementations of the RCF (Radio Control Function) and PPF (Packet
Processing Function), either in dedicated hardware, like in the BPU (Baseband
Processing Unit, traditional macro base-station) and in the RBU (Radio Baseband
Unit, traditional pico or micro base-station). The RCF and PPF can also be
implemented as a cloud solution as vRC (virtual Radio Controller) and vPP
(virtual Packet Processor),respectively.
The fronthaul interface is either C1 (CPRI) or C2. With C2, the beamforming
function (BFF) is in the Antenna Integrated Radio (AIR), while in the C1 case,
BFF is in the RPU or BPU.
C1 scales with number of antenna ports and bandwidth, which makes it not so
suitable with a massive number of antenna ports. C2 scales with number of layers
or beams and bandwidth, which makes it better suited for massive MIMO.
Figure 2-7: Ericsson RAN Architecture
The C5 interface is referred to as F1 by 3GPP and has a control plane part and a
user plane part.

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E5 is used for coordination between different nodes to enable Carrier
Aggregation, CoMP other coordination features. Ericsson provides Elastic RAN
(E-RAN) to enable a flexible and dynamic coordination and connectivity between
otherwise unsyncronized nodes.
1.5 Deployments
Different deployments of new RBS HW units will be possible, depending on
transport characteristics and scenario.
Figure 2-8: Site types
• RCF will most likely be deployed on CO and LS sites
• PPF will most likely be deployed on Ag and CO, but also more centralized to LS
sites or in some cases (mostly indoor?) distributed to H sites
• RBU and RRU will be deployed on AL
CO
CO
Ag
Cb
Local
LS
Regional
Ag
P
National
Cb
Tower
sites
(macro
RBSs)
Roof-top
sites (macro
RBSs)
AL
H
Antenna
Location
Hub site
Access site
(Central
office)
Local
Switching site
Primary Site
In-building
systems
(RDS,
Picos/APs,
DAS)
Legend:
RBU: Radio Baseband Unit
RRU: Remote Radio Unit
RCF: Radio Control Function
PPF: Packet Processing Function
Ag: Aggregation site
Cb: Curb site

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Figure 2-9: Traditional Deployment –
LTE Outdoor
Figure 2-10: Deployment evolvement – LTE Outdoor

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Figure 2-11: Virtualized RAN variety – Adding NR
Now it’s all about activating virtual functions in each site as previously mapped.
As one can see, different use cases can obviously share the same GPP.
Reconfigurations are extremely simple and can be quickly done at any time, but
this also leads us to reflect on one thing: the GPP placement is crucial.
The discussions around Core virtualization is ongoing and it does affect the RAN
architecture and it is important that RAN is a part of that discussion. The physical
allocation of GPPs is connected somehow to 5G discussions and extremely
important for RAN going forward.
The 4G network is the platform for 5G, so the engagement starts now.

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Figure 2-12: 5G network virtualization
The architecture evolution of the radio access network is primarily driven by
higher requirements on application coverage (bitrate coverage) and capacity
demands. The general receipe for improved coverage and capacity is to use a
combination of improving the performance of the macro-base stations, densify
the macro base-station grid, add smal-cells and install/improve in-building
systems, see the Hetnet Handbook. The best way forward is different for different
operators and there is no one-size-fits-all general solution.
There are also different types of deployment architectures, both for outdoor base-
stations and in-building systems. In its physical build three is a set of possible
sites that can be used for deployment.
The antenna site is as the name suggests the position where the RBS antennas are
mounted. For macro-base stations this is typically in the top of radio towers, on
building roof tops or on walls of buildings. It is the position of the antennas that
sets the base line for the radio characteristics of the network, its radio coverage
and interference, sometimes refered to as the ”Radio geometry”. In most outdorr
deployments there will also be a hub site.
The hub-site is a site appropriate for hosting base-band equipment, a mobile
backhaul PE router and possibly also RUs (in classic deployments not using
main-remote or C-RAN architectures). The most common deployment
architecture for macro base-stations is today a main-remote architecture where
the Hub site hosts base-band equipment while the RUs are located at the antenna
sites to avoid extensive feeder loss in cables between the DU and the RU. Indeed,
to minimize the feeder loss several deployements use the Antenna-integrated
radio (AIR) concept where the RUs and antennas are integrated in one physical
node.
Hub Central Office Aggregation Switching Primary
Antenna
Critical Comm. &
MTC
Enterprise &
Industry
Enhanced Mobile
Broadband
Massive
MTC
UPF
CCF
PPF
SDM
General Purpose Processor General Purpose Processor General Purpose Processor General Purpose Processor General Purpose Processor
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
BPF
BPF
BPF
BPF
PPF
BPF
BPF
BPF
RCF RCF RCF RCF RCF
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
RCF
RCF RCF RCF RCF
RCF RCF RCF RCF
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
UPF
CCF
PPF
SDM
RCF RCF RCF
RCF
RCF
RCF

46.
Ericsson 5G RAN System Techniques
- 46 - © Ericsson AB 2017 LZT1381970 R1A
As is illustrated in the figure the Hub site can be at the base of the radio tower, on
the roof top close the antenna location (upper left) or somewhere inside the
building (upper second left). In all these deployments, the mobile traffic is
backhauled using IP, possibly carried over MPLS. A different deployment
architecture is that or C-RAN. In this architecture the base-band units are located
in the access site (central office) slightly higher up network (see ”C-RAN” in
figure”). In this case the CPRI protocol runs between the antenna sites (where the
RUs are located) all the way to the access sites where the DUs are situated. This
requires in reality native fiber optical links – either grey fiber or WDM – between
the antenna sites and the acccess sites. In this deployements there are no hub
sites.
From a radio perspective the main advantage of the C-RAN deployment for
macro sites are mainly the ability to do advanced low-latency COMP such as
joint combining, fast correlated scheduling and more. From a practical
perspective the digiital RBS hardware becomes easier to access, and for DU
maintanence a single site visit to the access site replaces a multitude of site visits
to the hubs.
The operator-owned central office is typically also easier to access than a hub site
that may be contracted from a building owner or other. The disadvantage of the
C-RAN solution is its need for dark fiber – or at least wavelengths services –
between each antenna location and the access site which in many markets is
expensive to lease. There is also a practical restriction on the distance (fiber
kilometers) between the antenna location and the access site set by latency
restrictions of around 100 microseconds RTT between the antenna site and the
access site. Though there is a growing interest in C-RAN architectures and some
operators with good access to fibers have such deployments in service, the main-
remote deployment architecture is expected to dominate near- and mid-term.
By letting aggregated RAN nodes handle mobility it’s possible to shield the Core
Network from a great deal of events (signaling) that would otherwise take place.
Figure 2-13: Reduced signaling in Core NW Mobility handled by V-RAN

47.
Ericsson 5G RAN Architecture
LZT1381970 R1A © Ericsson AB 2017 - 47 -
1.6 LTE/NR Integration
Figure 2-14: LTE-NR Interworking
The limited (spotty) coverage of a much higher band requires the UE to “anchor”
in a lower band coverage layer for mobility robustness (or have its context tossed
unreliably between large and small cells).
The higher band is used as a booster (primarily for downlink).
The anchor point is placed in the protocol entity where the data flow is split (i.e.
PDCP for the coverage cell).
In order for data to also get to the booster band we get a trombone effect since the
split is done at the coverage site.
This is especially bad when the data forwarded is very large (asymmetry)
› Solution based on dual connectivity, with common
CN is most promising since it will allow for
– Mobility robustness considering spotty NR coverage
– Fast UP switching and aggregation
– Support co-located and non-co-located sites
› Option 3/3A/3X: first step in NR deployment
– Leverage on LTE presence when deploying NR at higher
frequency (capacity boost) and overcome propagation
challenges
› This is also called
– Non-standalone NR (NSA)
– EN-DC (EUTRA-NR Dual connectivity)
Option 3/3A/3X
NR
EPC
LTE
CP+UP
eNB
gNB

48.
Ericsson 5G RAN System Techniques
- 48 - © Ericsson AB 2017 LZT1381970 R1A
Figure 2-15: Dual Connectivity
Dual Connectivity is used to connect LTE and NR. Nodes are connected via X2
and/or E5. No S1AP from NR node to EPC.
Two RRC protocol stacks co-exist and interwork.
Figure 2-16: Protocol stack for LTE/NR integration
In Non-standalone (NSA) solution, a UE can only camp on LTE. The UE access
in LTE, then add NR leg.
MeNB-RRC (Master eNB, LTE) has major functionality and connectivity to UE
(SRB etc).
SgNB-RRC (Secondary gNB, NR) has SgNB-functionality. NR node handled as
separate managed element.
UE data
TN hub
site
Without Split RAN Anchor in Low & Narrow Band
Boost from High & Wide band
With Split RAN
UE data
TN hub
site
PPF
RCF
Anchor in Low & Narrow Band
Boost from High & Wide band

49.
Ericsson 5G RAN Architecture
LZT1381970 R1A © Ericsson AB 2017 - 49 -
Figure 2-17: NR: Standalone vs non-standalone
Dual connectivity is illustrated in the figure below.

50.
Ericsson 5G RAN System Techniques
- 50 - © Ericsson AB 2017 LZT1381970 R1A
Figure 2-18: What is dual connectivity?
To cover the Dual Connectivity concept, we first need to have a look at the
definitions and terminology. The definitions of DC are from 3GPP Rel 12.
Figure 2-19: Dual Connectivity Definitions
Different options for standalone NR (SA NR) and non-standalone NR (NSA NR)
are shown in the figure below.
› DC (Dual Connectivity)
– A UE in RRC_CONNECTED is configured with Dual Connectivity when configured with a Master and a Secondary Cell Group
› PCell (Primary Cell)
– The cell, operating on the primary frequency, in which the UE either performs the initial connection establishment procedure or
initiates the connection re-establishment procedure, or the cell indicated as the primary cell in the handover procedure
› SCell (Secondary Cell)
– A cell, operating on a secondary frequency, which may be configured once an RRC connection is established and which may be
used to provide additional radio resources
› MCG (Master Cell Group)
– For a UE not configured with DC, the MCG comprises all serving cells. For a UE configured with DC, the MCG concerns a subset of
the serving cells comprising of the PCell and zero or more secondary cells
› SCG (Secondary Cell Group)
– For a UE configured with DC, the subset of serving cells not part of the MCG, i.e. comprising of the PSCell and zero or more other
secondary cells
› PSCell (Primary Secondary Cell)
– The SCG cell in which the UE is instructed to perform random access when performing the SCG change procedure
› SpCell (Special Cell)
– For Dual Connectivity operation the term Special Cell refers to the PCell of the MCG or the PSCell of the SCG, otherwise the term
Special Cell refers to the PCell

51.
Ericsson 5G RAN Architecture
LZT1381970 R1A © Ericsson AB 2017 - 51 -
Figure 2-20: Multiple architecture options
Bearer types definition:
In current 3GPP definition of MCG/MCG split and SCG/SCG split bearers is
connected to the user plane termination point (S1-U).
There is a need to clarify the definition.
The S1-U termination could be in any of the nodes in any of the cases (this is
hidden to the UE).
It is the path between UE and RAN that identifies the type of bearer.
gNB definition:
According to 3GPP a radio access node is called “gNB” if it is connected to Next
Gen Core. (if it is connected to EPC it is called “eNB”.)
EPC+
NextGen
Core
LTE NR NR
LTE LTE NR
OPTION 3
OPTION 2
OPTION 4
• Current architecture
• Supported in 3GPP
• Not supported in 3GPP

52.
Ericsson 5G RAN System Techniques
- 52 - © Ericsson AB 2017 LZT1381970 R1A
Figure 2-21: Dual Connectivity – vocabulary
In the product implementation “gNB” is the node that support “NR” as radio
access technology (regardless of core connection).
The concepts of MCG split bearer (option 3) and SCG split bearer (option 3x) are
illustrated below.
Figure 2-22: Split bearer overview
› MCG bearer: in dual connectivity, a bearer whose radio
protocols are only located in the MeNB to use MeNB
resources only.
› SCG bearer: in dual connectivity, a bearer whose radio
protocols are only located in the SeNB to use SeNB
resources.
› Split bearer: in dual connectivity, a bearer whose radio
protocols are located in both the MeNB and the SeNB
to use both MeNB and SeNB resources.
› “gNB*” is the node that support “NR” as radio access
technology.
*gNB definition in some 3GPP document is related to the connection to 5GC. (if it is connected
to EPC it is called “eNB”.)
LTE-PDCP
LTE-RLC
LTE-MAC
NR-PDCP
NR-RLC
NR-MAC
MCG
bearer
SCG
bearer
Option
3a)
M-split-
bearer
(Option 3)
SCG-split-
bearer
(Option
3x)
S1-U S1-U
SgNB
MeNB
MCG-split-
bearer
(option 3)
SCG-split-
bearer
(option 3x)
SCG bearer
(option 3a)
MCG
bearer
EPC
BB
RAC
LTE eNB NR gNB
S1-CP
BB 5216
SRB DRB
MCG split bearer
User plane and
control Plane via eNB
SCG split bearer
User plane via gNB
Control Plane via eNB
S1-UP
RCF
BB
LTE NR
PPF
X2
DRB
EPC
BB
RAC
LTE eNB NR gNB
S1-CP
BB 5216
SRB DRB
S1-UP
RCF
BB
LTE NR
X2
DRB
PPF

53.
Ericsson 5G RAN Architecture
LZT1381970 R1A © Ericsson AB 2017 - 53 -
The figure below illustrates different methods of how the user plane can be
handled.
Figure 2-23: User plane
NR Standalone (SA) requires 5GC and is supposed to be deployed by the
operators at a later stage.
Figure 2-24: Standalone NR
A summary of the 3GPP scenarios is illustrated and described below.
› When dual connectivity is setup, the user data can be transferred on both legs,
depending on the supported configurations and leg quality.
DC Fast
Switch
DC UL & DL
separation
DC DL
aggregation
DC UL
aggregation
PDCP
UL1
1)
2)
3)
DL1
UL2
DL2
RAN
2)
1) 3)
UL
DL
PDCP
UL1 DL1
RAN
PDCP
DL1 DL2
RAN
PDCP
UL1 UL2
RAN

54.
Ericsson 5G RAN System Techniques
- 54 - © Ericsson AB 2017 LZT1381970 R1A
Figure 2-25: 3GPP Scenarios
Option 2:
Pros with option #2:
* Standalone operation possible without need for LTE network nor LTE coverage
nor LTE spectrum
* Tight interwork (DC) functionality not needed to implement in the system and
UE
Cons with option #2:
* Robustness and performance from LTE network not available
* “Full coverage” needed for NR
* Requires inter-RAT functionality to LTE
* Requires all channels, functions and procedures to be implemented on NR in
UE and system
Note:
No legacy UE support
Evolved QoS used
38.xxx: 38-series or other new NR series
EPC
Option 1
5GCN
Option 2
LTE NR
Option 3/3A/3X
NR
EPC
LTE
CP+UP
eNB eNB
gNB
gNB
Option 4/4A
NR
5GCN
LTE
CP+UP
eNB
gNB
5GCN
Option 5
LTE
eNB
EPC
Option 6
NR
gNB
Option 7/7A
NR
5GCN
LTE
UP
CP+UP
eNB
gNB
Option 8/8A
NR
EPC
LTE
CP+UP
eNB
gNB

55.
Ericsson 5G RAN Architecture
LZT1381970 R1A © Ericsson AB 2017 - 55 -
Option 3/3a:
*) “eS1” refers to Rel-15 versions of S1-UP and S1-AP respectively.
Expect no or minor updates on S1 to support this. (Capabilities, AMBR etc)
**) Assumption that 38.xxx will specify NR container for NR leg, which goes
transparent or semi-transparent through MeNB
Pros with option #3/3a:
* Robustness and performance from LTE network available
* Easier implementation and specification versus NR standalone: does not require
all channels, functions and procedures to be implemented on NR in UE and
system
* Re-uses LTE and EPC investments and does not restrict timeplan to
introduction of NGCN
* Spotty introduction of NR possible, no need for “full coverage”
* In/out-of NR coverage hidden to core network
Cons with option #3/3a:
* Tight interwork (DC) functionality needed to be implement in LTE and UE
* Requires LTE network and LTE coverage and LTE spectrum
* No support for performance and functionality of NGCN
Note:
3 and 3a is the same in vRAN deployment
Legacy QoS used
Interwork across X2 also supported
38.xxx: 38-series or other new NR series
Option 4/4a:
Pros/cons with option #4:
* In case NR has spotty coverage it leads to many mobility actions (MeNB in
NR)
Note:
4 and 4a is the same in vRAN deployment

56.
Ericsson 5G RAN System Techniques
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Evolved QoS used
Interwork across X2 also supported
38.xxx: 38-series or other new NR series
Option 5:
In case “legacy PDCP” is used in this option: Multiplexing of packets from
different PDU sessions onto same DRB not possible with legacy PDCP
Pros with option #5:
* Performance and functionality of NGCN introduced in LTE
* Necessary stepping-stone to option 7/7a
* Enables same functionality (and thus SW track) for higher layers in LTE and
NR (at least RRC+PDCP)
Cons with option #5:
* LTE system (and UE) needs to implement support for NGCN
Note:
Evolved QoS used
38.xxx: 38-series or other new NR series
Option 7/7a:
**) Assumption that 38.xxx will specify NR container for NR leg, which goes
transparent or semi-transparent through MeNB
In case “legacy PDCP” is used in this option: Multiplexing of packets from
different PDU sessions onto same DRB not possible with legacy PDCP
Pros with option #7/7a:
* Performance and functionality of NGCN introduced in LTE+NR interworking
* Enables same functionality (and thus SW track) for higher layers in LTE and
NR (at least RRC+PDCP)
Cons with option #7/7a:
* Tight interwork (DC) functionality needed to be implement in LTE and UE
* Requires LTE network and LTE coverage and LTE spectrum
Note:

57.
Ericsson 5G RAN Architecture
LZT1381970 R1A © Ericsson AB 2017 - 57 -
7 and 7a is the same in vRAN deployment
Evolved QoS used
Interwork across X2 also supported
38.xxx: 38-series or other new NR series
Different operators will migrate in different ways
A likely starting point (early adopters) is:
LTE+NR interwork with EPC (option 3/3a) and then migration to NGCN from
there
Another feasible starting point is:
NGCN from start (option 5), or NR standalone (option 2)
In any case, support for “previous versions” of UEs are most likely mandatory
Some more details on option 3 and its flavors are illustrated in the figure below.
Figure 2-26: NSA RAN Options 3, 3a, “3x” 3GPP TS 38.801 overview
UE type options are shown in the figure below.

58.
Ericsson 5G RAN System Techniques
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Carrier Aggregation within LTE and within NR and elastic RAN not shown in
the options but assumed for all combinations of UE support expected in a specific
UE implementation, ex UE of types 2-4 may also support “LTE legacy”
For option 6 a separate UE implementation, different from “NR SA”, is needed
and is not further defined here.
*) Here assumed that evolved QoS supported with NextGenCore (NGCN) and
not with EPC
Figure 2-27: UE types
For DC between LTE and NR where MCG comprises LTE cell(s) and SCG
comprises NR cell(s), the gNB as the secondary node is not required to broadcast
system information other than for radio frame timing and SFN. In this case,
system information (for initial configuration) is provided for the UE by dedicated
RRC signaling via LTE eNB as the master node. The UE acquires, at least, radio
frame timing and SFN of SCG from the NR-PSS/SSS and PBCH of NR PSCell.
For DC between LTE and NR where MCG comprises NR cell(s) and SCG
comprises LTE cell(s), system information (for initial configuration) is provided
for the UE by dedicated RRC signalling via NR gNB as the master node. In this
case, the UE acquires radio frame timing and SFN of SCG from PSS/SSS and
MIB on LTE PSCell.
1. “LTE legacy”: SA LTE UE without NGCN* support
2. “Evolved LTE”: SA LTE UE with NGCN* support
3. “LTE+NR Phase 1”: NSA LTE+NR UE without NGCN*
support
4. “LTE+NR Full”: NSA LTE+NR UE with NGCN* support
5. “NR SA”: SA NR or LTE (not simultaneously) UE with
NGCN* support. UE is “NR SA” while in NR and “Evolved
LTE” while in LTE
Option 5
Option 3/3a/3x
Option 7/7a and/or 4/4a
Option 2
Option 5

59.
Ericsson 5G RAN Architecture
LZT1381970 R1A © Ericsson AB 2017 - 59 -
NOTE: It is FFS how to handle changes of system information in the secondary
node.
1.7 Architecture Summary
5G work started in 3GPP:
Requirements on 5G have been captured
Ericsson plans for a flexible 5G architecture
Support LTE->NR migration and tight interworking
When possible, ensure reuse of core LTE design still allowing for an
unconstrained development of NR
Ericsson has a clear standardization strategy
Define a RAN architecture that allows for flexible virtualization => avoid
detailed specification of a split RAN architecture
Ensure a good quality standard for key interfaces and functions subject to inter-
vendor interoperability requirements
Figure 2-28: Architecture Summary
2 Summary
› 5G work started in 3GPP:
› E/// plans for a flexible 5G architecture
– LTE->NR migration
– Tight interworking
› Ericsson has a clear standardization strategy
– Flexible virtualization
– Inter-vendor interoperability requirements

60.
Ericsson 5G RAN System Techniques
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Figure 2-29: Chapter 2 Summary
2 Explain Ericsson’s view on the 5G RAN
Architecture
2.1 Describe nodes and interfaces
2.2 Describe the Dual Connectivity architecture and
options

61.
Introduction to NR
LZT1381970 R1A © Ericsson AB 2017 - 61 -
3 Introduction to NR
Objectives
Figure 3-1: Objectives
3 Describe the higher layers of NR
3.1 Explain the functions of MAC, RLC, PDCP, such as Scheduling, link
adaptation, Fast HARQ, ARQ and PDCP split
3.2 Describe the L3 signaling basics (RRC, NAS, Call flows)
3.3 Explain the NR cell concept
3.4 Explain QoS in 5G

62.
Ericsson 5G RAN System Techniques
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1 Introduction to NR
This figure below shows an overview of some of the NR technology components
deemed to be key for the 5G wireless access.
Figure 3-2: NR Technology Areas - Flexible and Scalable Design
5G wireless access is the overall wireless access solution of the future, fulfilling
the needs and requirements for 2020 and beyond.
LTE will continue to be an important part of that future. Ericsson sees the
evolution of LTE being a key part of the overall 5G wireless access solution.
More specifically, the evolution of LTE will apply to existing spectrum currently
used by LTE, spectrum for which the possibility to introduce 5G capabilities in a
backwards compatible way is highly beneficial and, in many cases, vital.
Parallel to the evolution of LTE, new radio-access technology (denoted NX or
NR), not constrained by backwards compatibility, will be developed. Such
technology will, at least initially, target new spectrum. A main part of such
spectrum will be available at higher frequencies (above 10 GHz). However, there
may also be new spectrum at lower frequencies for which new non-backwards-
compatible technology may also apply.
In a longer time-perspective, as more devices supporting new technology will be
available, one could of course also envision that the new technology will migrate
into spectrum currently used by LTE.
Extension to higher frequencies
Complementing lower frequencies for extreme capacity and data rates in dense
areas.
Flexible Physical Layer

63.
Introduction to NR
LZT1381970 R1A © Ericsson AB 2017 - 63 -
Flexible Numerology
Spectrum flexibility
Spectrum sharing
 Unlicensed
 Shared licensed
 Network sharing
Complementing dedicated licensed spectrum
Multi-antenna technologies
For higher as well as lower frequencies
 Beam-forming for coverage
 Multi-user MIMO for capacity
Multi-site coordination
 Multi-site transmission/reception
 Multi-layer connectivity
Access/backhaul integration
 Same technology for access and backhaul
 Same spectrum for access and backhaul
Device-to-device communication
 Direct communication
 Device-based relaying
 Cooperative devices
Ultra-lean design
 Minimize transmissions not related to user data
 Separate delivery of user data and system information
 Higher data rates and enhanced energy efficiency
System Plane and User Plane separation
Decouple system information delivery and data functionality
Machine Type Communication
Massive and Critical MTC

64.
Ericsson 5G RAN System Techniques
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1.1 RRC Inactive state
Studies of existing network shows that operators use LTE IDLE as primary sleep
state in LTE.
LTE IDLE is inefficient for short connections sending little data (requires a lot of
CN signaling) and many smartphone/MTC connections send little data.
Many users are typically stationary (ACTIVE->IDLE->ACTIVE in the same
area/node/cell).
This topic is addressed in LTE Rel-13 with the RRC Suspend/Resume solution.
In NR, it is desirable to evolve this further to a new RRC state (RRC inactive or
dormant state) keeping S1* connection up.
Figure 3-3: Need for RAN controlled sleep state
The 5G sleep state should support;
 DRX (from milliseconds to hours), with preferably lower power
consumption than today
 UE context is maintained in RAN (including S1*)
 UE controlled mobility, e.g. the UE should be allowed to move around
in the local area without notifying the network
 RAN paging within local areas
 Efficient handling of smartphone and MTC devices with only short
burst of data followed by long inactivity
 No CN signaling required
 CN used as a fallback / recovery solution (does not need to be as
optimized)

65.
Introduction to NR
LZT1381970 R1A © Ericsson AB 2017 - 65 -
Figure 3-4: NR DORMANT RRC state
RRC supports the following three states which can be characterised as follows:
RRC_IDLE:
 Cell re-selection mobility;
 [FFS: The UE AS context is not stored in any gNB or in the UE;]
 Paging is initiated by CN;
 Paging area is managed by CN.
RRC_INACTIVE:
 Cell re-selection mobility;
 CN – NR RAN connection (both C/U-planes) has been established for
UE;
 The UE AS context is stored in at least one gNB and the UE;
 Paging is initiated by NR RAN;
 RAN-based notification area is managed by NR RAN;
 NR RAN knows the RAN-based notification area which the UE
belongs to;
RRC_CONNECTED:
 The UE has an NR RRC connection;
 The UE has an AS context in NR;
 NR RAN knows the cell which the UE belongs to;
 Transfer of unicast data to/from the UE;
 Network controlled mobility, i.e. handover within NR and to/from E-
UTRAN.
CN
gNB
gNB
gNB
UE
UE is in low power state,
with DRX (from ms to hours)
CN/RAN connection is kept
UE is allowed to move
around in local area
without telling network
Paging
DL Packet arrive, which
triggers RAN paging

66.
Ericsson 5G RAN System Techniques
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NOTE: How to model RRC_INACTIVE in the specification will be decided in
the work item phase.
Figure 3-5: Combined LTE/NR states
1.2 NR Cell
In NR, cells exist, as in all previous mobile generations. However, the 3GPP
specification enables a significant different cell deployment flexibility.
Figure 3-6: NR Cell
It is important that this difference is understood so the product flexibility is
secured, to utilize this key NR capability.
NR
RRC_CONNECTED
NR RRC_INACTIVE
Detached
ECM/RRC
IDLE
RAN context (RRC Connected) No RAN context (RRC Idle)
UE is either
configured
with NR or
LTE radio or
both
UE is either
camping in
NR or LTE
Fast transitions
Inter-RAT mobility
without telling network
Fast inter-RAT
switch
SS1
“SIBs” or “SIB-table” area
“SS Block” transmissions
defines the NR Cell
› NR Cell: Defined by the (same) SS* Block information
– SS Block
› SS: NR-PSS / NR-SSS -> carry Cell-ID
› NR-PBCH: Contains a MIB (optional)
– SIB-table
› Contain the configuration for system access
› May contain SI for more than one cell
* SS: Synchronization Signal

67.
Introduction to NR
LZT1381970 R1A © Ericsson AB 2017 - 67 -
Figure 3-7: NR cell measurement signals
The NR Cell is defined by the Synchronization Signal Block (SS Block)
information. SS-blocks consist of Primary Synch Signal (PSS), Secondary Synch
Signal (SSS) and Physical Broadcast Channel (PBCH). More about this later in
the course.
Figure 3-8: NR cell
The same SS Block info defines one NR cell. Different cells can have the same
access configuration.
Similar to LTE
Sync signal (PSS/SSS) with PCI
MIB
SIB
Different from LTE
• Less frequent reference signals
(lean)
• No CRS (PSS/SSS and CSI-RS
used instead)
• Minimalistic SIB content, more is
sent UE dedicated
› NR Cell definition
– Defined by the (same) SS Block information
– Received time synchronized (within a cyclic prefix) or
time orthogonal (Analog beam sweep*)
› Cells can have same access configuration
 Can listen to same RACH (share RACH resource)
 UE reception (paging, RAR) is not cell but timing related
e.g. RAR can come from another than UE camping cell
› SIB table does not need to be cell unique
−Single Frequency network (SFN)
−Not all antennas need to transmit a SIB table
SS1 SS2
SS1
SS1 SS2
“SIBs” or “SIB-table”
NR Cell
Time
*) Same SS Block information but different SS Block sub index to enable UE beam identification

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The NR cell scales with control signaling load and not user data load. Therefore,
it scales and can be shaped independently from user plane areas.
Figure 3-9: NR cell - cell structure
This concept is in line with the CP/UP separation, discussed earlier in this course.
Also, it is in line with the Ultra-lean design concept, where we may use silent
frequency carriers that can be activated only when users are active on these
frequencies.
Figure 3-10: NR cell Frequency carriers
› NR cell size determined by
› IDLE/RRC INACTIVE control load (Paging, RACH, RAR) not user data load
› Synchronized transmission timing i.e. within a Cyclic prefix
NR Cell shape independent of user plane capacity needs
OR
OR
~3.5 GHz NR IDLE NR Cell broadcast
Silent frequency carriers
• Nothing broadcasted unless there are active
users utilizing these frequencies
• If there is active traffic on a frequency carrier, RS
broadcast might be needed on these, which may
be independent of NR Cell
Frequency [GHz]
100
0
Capacity booster carriers do not need ‘always on’ broadcasted SI
Frequency carrier ≠ NR cell
NR cell
• Broadcast when IDLE UE’s are expected to find/camp
on it and report the carrier when doing Frequency/Cell
search for IDLE mobility

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The idle mode broadcast (SS-blocks, System Info etc) can be done in the NR cell,
which is decoupled from the silent frequency carriers.
Figure 3-11: NR cell Massive site deployment
The figure below shows a summary of the NR cell deployment. We can see the
flexibility in terms of NR cell deployment, SIB area deployment, HW
deployment and RACH/paging resource deployment.
~3.5 GHz NR IDLE cell broadcast
Silent TRxP
• Nothing broadcasted unless there are
active users utilizing its frequency
carriers
• Can support both same and different
frequencies as other antennas in its
vicinity
• Still possible to perform paging
• Still possible to receive RACH
• In case of shared baseband not even
RS broadcast needed
Capacity booster sites do not need “always on” broadcasted SI

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Figure 3-12: NR cell deployment Summary
1.3 System broadcast
To separate the CP and UP, system broadcast should be transmitted
independently from the user plane data. This allows for flexibility when
dimensioning control plane and user plane and when designing NR cells and
sites.
Figure 3-13: System access
Cell_B
Cell_C Cell_D
NR Cell - Time synchronized SS Block index
Resource area – Same RACH/RAR/Paging resources
Common L1 HW
SIB area – Common Access configurations content
Cell_A
Cell_E Cell_F
Cell_G
TRxPs
SFN
CoMP
HWs
Frequency [GHz]
100
0
Lean system
Cell_G
Any cell size – no coverage compromise
Any size cell - Improved coverage
Flexible network
deployment
Any cell size – infrastructure independence
Any size cell – Improved coverage
User plane scalability independence
System control
Decouple system information delivery and data
functionality
› Why?
 -To fully enable usage of advanced
(e.g. massive-MIMO) antenna systems
 -To enhance network energy performance
 -Scalability, performance, forward
compatibility
System control
System control

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System information is divided into ‘minimum SI’ and ‘other SI’. Minimum SI is
periodically broadcast. The minimum SI comprises of basic information required
for initial access to a cell and information for acquiring any other SI broadcast
periodically or provisioned via on-demand basis, i.e. scheduling information. The
other SI encompasses everything not broadcast in the minimum SI.
The other SI may either be broadcast, or provisioned in a dedicated manner,
either triggered by the network or upon request from the UE. For the other SI
required by the UE, before the UE sends the other SI request the UE needs to
know whether it is available in the cell and whether it is broadcast or not. The UE
in RRC_IDLE or RRC_INACTIVE should be able to request the other SI without
requiring a state transition. For the UE in RRC_CONNECTED, dedicated RRC
signaling can be used for the request and delivery of the other SI. The other SI
may be broadcast at configurable periodicity and for certain duration. It is
network’s decision whether the other SI is broadcast or delivered through
dedicated UE-specific RRC signaling.
Figure 3-14: System broadcast
Each cell, in which the UE is allowed to camp, broadcasts at least some contents
of the minimum SI, while there may be cells in the system on which the UE
cannot camp and do not broadcast the minimum SI. For a cell/frequency that is
considered for camping by the UE, the UE should not be required to acquire the
contents of the minimum SI of that cell/frequency from another cell/frequency
layer. This does not preclude the case that the UE applies stored SI from
previously visited cell(s). If the UE cannot determine the full contents of the
minimum SI of a cell (by receiving from that cell or from valid stored SI from
previous cells), the UE shall consider that cell as barred. It is desirable for the UE
to learn very quickly that this cell cannot be camped on.
NOTE 1: Reception of the minimum SI via SFN is not precluded and pending the
outcome of RAN1 study.
› SS Block
– SS: NR-PSS / NR-SSS
– NR-PBCH: Contains a MIB (optional)
– Transmitted every X ms {e.g. 5 or 80 ms}
› SIB-table
– Contain the configuration for system access
– May contain SI for more than one cell
time
NR-PSS / NR-SSS
“SS Block”
NR-PBCH
“SIBs” or “SIB-table”
SS1
“SIBs” or “SIB-table” area
“SS Block” transmissions
defines the NR Cell
X ms
› The broadcasts minimum information about how to access the system

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NOTE 2: It is FFS whether Msg.1 and/or Msg.3 are/is used to carry the other SI
request.
NOTE 3: It is FFS whether there is an additional indication that an on- demand SI
is actually being broadcast at this instant in time.
A SIB can contain several Access Configurations.
Received SS block contains an ”index” which access configuration to be used.
However, it is not yet decided how the ”index” will look like.
 Alternative 1: Combining PCI and ”System Information value” in MIB to
extract index.
 Alternative 2: Code PBCH in several parts and let the start position
implicit mean index (chosen for EIPS).
Different SS Block index can have exactly the same Access Configuration
Figure 3-15: Index based SI Provisioning
› The SS Block index points out the Access Configuration to be used by the UE
– UEs in IDLE mode or RRC INACTIVE mode camp on SS Block
– Different SS Block index can have exactly same Access Configuration
– Multiple SS Block index can be transmitted from the same antenna
...
5-80ms
Time
SIB SS2
SS1
SIB Table
SS1 Access configuration x
SS2 Access configuration y
SS3 Access configuration z
SS1 SS2
“SIBs” or “SIB-table”
SS1
SS3
or
UE “best SS” view during mobility

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Figure 3-16: Connection establishment Overview
Figure 3-17: Inactive to active
1.4 Channel Structure
Figure 3-18 illustrates the channel structure in NR, from Logical channels via
transport channels to Physical channels. It also shows the reference signals and
the Synchronization Signals.
NR eNB
UE NR eNB
1. PRACH preamble
2. Random Access Response
3. RRC Connection Request
4. RRC Connection Setup
5. RRC Connection Complete
Access Information
acquisition
CN
6. Common security setup
8. RRC connection re-configuration
7. Common UE capability
Random Access
RRC connection est.
Single attach
Access information
Inactive to active 10. RRC connection re-activation
9. RRC connection inactivation
Reconfiguration
Similar to LTE
Common LTE/NR
security context,
S1* termination
Most important
transition to
optimize
RRC_connected
RRC_inactive
RRC_connected
› Inactive state
– RRC connected, SRBs & DRBs maintained
– Support for very long DRX
– UE controlled mobility
› RRC Connection Re-activation
– Single RRC procedure to re-establish
signalling and data radio bearers
– UE RRC Context ID used to locate UE context
– Includes security re-activation
› Many options for lower layer access
– Low frequency
– High frequency
– SS based
– CSI-RS based
UE NR eNB
Context fetch
LTE eNB
RRC connection re-activation request (SRB0 message)
RRC connection re-activation (Configuration of SRBs, DRBs)
RRC connection re-activation complete (FFS if needed)
RRC connection inactivation

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The physical broadcast channel (PBCH) is used for MIB distribution. The PBCH
design supports blind detection of used numerologies. PBCH supports
beamforming and/or repetition to improve link budget.
System information can be distributed via PDSCH or via PBCH, depending on
the UE state. The MIB is periodically broadcasted in PBCH.
Figure 3-18: Channel Structure
The physical downlink control channel (PDCCH) schedules physical downlink
shared channel (PDSCH) and physical uplink shared channel (PUSCH). PDCCH
spans only a fraction of the system bandwidth and has its own demodulation
reference signals enabling user-specific beamforming.
PDCCH carries downlink control information, DCI. DCI includes, but is not
limited to, scheduling information for PDSCH and PUSCH. A PDCCH also
contains reference signals for demodulation, the user identity (either explicitly or
implicitly, e.g. CRC mask) and CRC for validation.
PDCCH is transmitted preferably in the first OFDM symbol in an NR DL slot, a
multi-symbol PDCCH can be envisioned if needed from a capacity and/or
coverage viewpoint. A PDCCH is transmitted in a part of the spectrum. The size
of this part depends on the channel conditions and payload size. Multiple
PDCCHs may be transmitted, frequency multiplexed or/and space-multiplexed in
the same OFDM symbol. Space/frequency resources unused for PDCCH
transmission may be used for PDSCH transmission.
PCH BCH
PCCH BCCH DTCH DCCH
Logical
Channels
Transport
Channels
DL-SCH
Physical
Channels
PDSCH
PBCH
CCCH
PDCCH
DCI
DTCH DCCH
UL-SCH
PUSCH
CCCH
PUCCH
UCI
PRACH
DL UL
Reference and
Sync Signals
PSS SSS DMRS SRS DMRS
CSI-RS PRACH
Preamble
DMRS DMRS
MIB
SCP Data and dedicated control SCP
SS
PTRS
MCCH MTCH
MCH
PTRS
SIBs
MAC
RACH

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1.4.1 DL reference and sync signals
Figure 3-19: DL Physical signals
The Sync Signal (SS) is used to indicate an entry in MIB and to establish some
level of slot synchronization for at least random access preamble transmission.
SS are constructed in a similar way as the synchronization signal in LTE by
concatenation of a primary signature sequence (PSS) and a secondary signature
sequence (SSS).
Channel state information reference signals (CSI-RS) are transmitted in DL and
are primarily intended to be used by UEs to acquire CSI. CSI-RS are grouped
into sub-groups according to the possible reporting rank of the UE measurement.
Each sub-group of CSI-RS represents a set of orthogonal reference signals.
Phase and frequency tracking reference signal (PTRS) can be used for e.g. for
high doppler channel estimations, phase compensation and are UE-specific
reference signals, associated with PDSCH and PUSCH.
The PTRS are a valid reference for PUSCH demodulation if the PUSCH
transmission is associated with the corresponding antenna port.
Signal Purpose
Synchronization signal (SS) Used to synchronize time and frequency for random access. Consists of PSS and SSS.
Primary synchronization signal (PSS) Detection of DC carrier and time sync.
Secondary synchronization signal (SSS) Frame sync
Phase and frequency tracking reference signal (PTRS) To compensate for phase shifts. Associated with PDSCH.
Demodulation reference signal (DMRS) for PDCCH Demodulation reference signals for PDCCH
Channel state information reference signal (CSI-RS) Used for channel state measurements to aid rank and MCS selection.
Demodulation reference signal (DMRS) for PDSCH Demodulation reference signals for PDSCH
Physical
Channels
PDSCH
PBCH PDCCH PUSCH PUCCH PRACH
Reference and
Sync Signals
PSS SSS DMRS SRS DMRS
CSI-RS PRACH
Preamble
DMRS DMRS
MIB
SS
PTRS
PTRS

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For CP-OFDM, time-domain density mapped on every other symbol and/or every
symbol and/or every 4-th symbol is supported. For a given UE, the designated
PT-RS is confined in scheduled resource as a baseline. Presence/patterns of PT-
RS in scheduled resource are UE-specifically configured by a combination of
RRC signaling and association with parameter(s) used for other purposes (e.g.,
MCS) which are (dynamically) indicated by DCI. Whether PT-RS can be present
or not depends on RRC configuration. When configured, the dynamic presence is
associated with DCI parameter(s) including at least MCS. Multiple PT-RS
densities defined in time/frequency domain are supported. When present,
frequency domain density is associated with at least dynamic configuration of the
scheduled BW. UE can assume the same precoding for a DM-RS port and a PT-
RS port. Number of PT-RS ports can be fewer than number of DM-RS ports in
scheduled resource.
1.4.2 UL reference and sync signals
Figure 3-20: UL Physical signals
Physical random access channel (PRACH) preamble is constructed by
concatenating several short sequences, each sequence being of the same length as
an OFDM symbol for other NR UL signals. These short sequences can be
processed using the same FFT sizes as other UL signals thus avoiding the need
for dedicated PRACH hardware. This format also enables handling of large
frequency offsets, phase noise, fast time varying channels, and several receiver
analog beamforming candidates within one PRACH preamble reception.
Physical
Channels
PDSCH
PBCH PDCCH PUSCH PUCCH PRACH
Reference and
Sync Signals
PSS SSS DMRS SRS DMRS
CSI-RS PRACH
Preamble
DMRS DMRS
MIB
SS
PTRS
PTRS
Signal Purpose
PRACH preamble
Initial transmission of UE. Contention based such that the PRACH preamble must be detected with
high reliability. Timing and receiver beam estimation.
Sounding reference signal (SRS)
Used to estimate the UL channel and to set the DL pre-coding in the transmitter in reciprocity-based
MIMO.
Demodulation reference signal (DMRS) for PUCCH Demodulation reference signals for PUCCH
Demodulation reference signal (DMRS) for PUSCH Demodulation reference signals for PUSCH
Phase and frequency tracking reference signal (PTRS) To compensate for phase shifts. Associated with PUSCH