Applications & requirements Concepts Architecture …...SDN and NFV provide means to fulfill future requirements of 5G architecture Open interfaces To help integrate different components

5G

Applications & requirements

Concepts

Architecture and protocols

Cellular Communication Systems 2Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2018

Applications and Requirements

Limits of 4G New Applications 5G Requirements


5G – Extension of Current Limits

Dramatic change of mobile communication landscape Data-hungry applications requiring further increase of network capacity Internet of Things (IoT) results in a huge number of connected

devices New applications with extreme low latency and high reliability

requirements (M2M, V2X)

Limits of 4G to fulfill these requirements due to applied methods and system structure

Limits in network capacity due to access scheme and resource management

Latency limit > 20ms due to frame structure and network topology

Transmission techniques are further advancing Increased signal processing capabilities allow new approaches Modern components (amplifier, mixers, etc.) allow cost-efficient use also

on higher frequency bands, esp. > 10 GHz

Target: 5G mobile communication systems for 2020


5G – Applications

Source: “NGNM 5G White paper,” NGNM Alliance, Feb. 2015


Key Capabilities

Key capabilities for different usage scenarios

Enhancement of key capabilities from IMT-Advanced to IMT-2020

Source: “IMT Vision – Framework and overall objectivesof the future development of IMT for 2020 and beyond,“ Recommendation ITU-R M.2083-0, Sep. 2015


5G Requirements and Performance Targets

High Data Rates

10 – 100 x increaseeven for high mobility

High System Capacity

1000 x improvementin capacity per area

Massive DeviceConnectivity

100 x improvementeven in crowded areas

Reduced Latency

Latency < 1msend-to-end

Energy Saving &Cost Reduction

Network & terminalsincl. backhaul


Concepts

New Spectrum Duplex Scheme Physical Layer Flexibility Beam Forming Device-to-Device Communication Ultra-Lean Design Decoupling of User Data and System Control Information Integration and Internetworking with 4G Software-Defined Networking Network Virtualization Network Slicing


New Spectrum

From sub-GHz to mm-Wave

Lower frequencies for full-area coverage

Complementary use of higher frequencies

⇒ Achieve extreme traffic capacity and data rates in dense scenarios


OFDM as a Base for Physical Layer Flexibility

Modifying characteristicsby digital signal processing


Enhanced Multiple-Access Schemes

Application of non-orthogonal access schemes (NOMA) or sparce code multiple access (SCMA)

Usage of advanced interference cancellation techniques Exploitation of pathloss differences between the users Random access based data transmission

Source: Saito et al: Non-Orthogonal Multiple Access (NOMA) for Future Radio Access, VTC, 2013

5G


Duplex Arrangement

FDD dominating in lower (licensed) bands Coverage benefits Avoids some nasty interference

situations (BS ↔ BS, device ↔ device)

TDD more relevant for higher bands targeting very wide bandwidths in dense deployments Easier to find unpaired spectrum More dynamic traffic variations Access nodes and devices

becoming more similar


Beam-Forming

5G air-interface optimized for beam-formed operation Beam-centric design considerations:

Self-contained transmissions allowing for rapid beam re-direction “Beam mobility” – Mobility between beams rather than nodes System plane matched to beam-formed user plane


Device-to-Device Communication

D2D communication as well-integrated part of the overall wireless access solution Direct peer-to-peer D2D communication as an overall more efficient mode Direct D2D communication as a means to extend coverage (device-based

relaying) High-speed inter-device communication provides “joint” transmission

and/or reception between multiple devices (cooperative devices)


Ultra-Lean Design

Minimization of network transmissions not directly related to user-data delivery Resources are treated as

undefined unless explicitly indicated otherwise

Advantages Reduced interference Higher achievable data rates Enhanced network energy

performance Future-proof design


Decoupling of User Data and System Control Information

Scaling of user-plane capacity independently of system control resources Well-matched to beam-formed radio-interface design Well-aligned with ultra-lean design


Integration with 4G/LTE-A-Pro

Evolution of existing technology + New radio-access technology LTE will be integral part of the overall 5G radio solution Application of selected 5G technologies also to LTE-Advanced


Interworking of Technologies

5G shall tightly interwork with existing 4G networks Offers a smooth way for migration to 5G

Dual connectivity Initial deployment on higher

bands for extreme traffic capacity and data rates

LTE on lower bands for full coverage and robust mobility

Smooth introduction of 5Gin new spectrum

User plane aggregation Migration into legacy bands

while retaining full bandwidthavailability for new devices

Smooth migration of new RAT into legacy bands


SDN & NFV as Enablers for 5G

Network Function Virtualization (NFV) is complementary to Software Defined Networking (SDN) SDN: Abstraction and programmability of virtualized transport NFV: Realization of network functions on commodity IT servers by means

of virtualization and cloud technologies

SDN and NFV provide means to fulfill future requirements of 5G architecture Open interfaces To help

integrate different componentsholistically

HW independency Possibledue to decoupling of SW and HW

Pre-standardization by ETSI NFV-ISG Source: “Network Functions Virtualisation –Introductory White Paper,” ETSI, 2012


Software Defined Networking (SDN)


Network Function Virtualisation (NFV)

Source: “Network Functions Virtualisation – Introductory White Paper,” ETSI, 2012


SDN & NFV Properties

Benefits CAPEX reduction

Use of high volume industry standard hardware Open interface for holistic integration of components & applications Multi-vendor ecosystem for HW, platform and telco applications (avoiding vendor

lock-in) Multiplexing gain: Optimization of resource sharing between different services

OPEX reduction Quick & easy deployment of new services Dynamic and flexible resource allocation (scale-in/ scale-out) Energy-efficient operation (shut-down of unused resources)

Resiliency Fault tolerance - resource usage by different geographical areas Auto-healing

Challenges Significant overhead: processing power, signaling, etc. Increased complexity of operation Handling of latency for delay-critical items


Network Slicing

Slicing of a single physical network into multiple, virtual, end-to-end networks Logical isolation of devices, access, transport and core network for different

types of services with different characteristics and requirements Dedicated (virtual) resources for each slice isolated from other slices Single physical network to support a variety of devices

with different characteristics and needs, e.g. mobile broadband, massive IoT, mission-critical IoT, etc.

with different features wrt mobility, charging, security, policy control, latency, reliability, etc.

5G Use Case Example RequirementsMobile Broadband 4K/8K UHD, hologram,

AR/VRHigh capacity, video cache

Massive IoT Sensor network (metering, agriculture, building, logistics, city, home, etc.)

Massive connection (200,000/km2)mostly inmobile devices

Mission-critical IoT Motion control, autonomous driving, automated factory, smart-grid

Low latency (ITS 5ms, motion control 1 ms)high reliability


Network Slicing


Network Slicing, SDN and NFV


Mobile Network Architecture – Evolution Path


5G Architecture and Protocols (Rel. 15)

Network Architecture Service Based Architecture Protocol Architecture and Protocols Mobility Management Quality of Service Ultra-Reliable Low Latency Communication (URLLC)


5G Architecture: Next Generation-RAN and 5G Core

UPF User Plane FunctionAMF Access and Mobility Management FunctiongNB Node providing NR user plane and control plane protocol terminations towards the UE, and

connected via the NG interface to the 5GCng-eNB Node providing E-UTRA user plane and control plane protocol terminations towards the UE,

and connected via the NG interface to the 5GC

gNB

ng-eNB

NG

NG NG

Xn

NG-RAN

5GC

AMF/UPF

gNB

ng-eNB

NG

NG NG

Xn

AMF/UPF

Xn

Xn

NG NG

Source: TS 38.300: NR; NR and NR-RAN Overall description (Stage 2)


Functional Split between NG-RAN and 5GC

internet

gNB or ng-eNB

RB Control

Connection Mobility Cont.

MeasurementConfiguration & Provision

Dynamic Resource Allocation (Scheduler)

AMF

UPF

Inter Cell RRM

Radio Admission Control

NG-RAN 5GC

Mobility Anchoring

Idle State Mobility Handling

NAS Security

SMF

UE IP address allocation

PDU Session Control

PDU Handling

internet

eNB

RB Control


eNB MeasurementConfiguration & Provision


PDCP

PHY

MME

S-GW

S1MAC

Inter Cell RRM


RLC

E-UTRAN EPC

RRC

Mobility Anchoring

EPS Bearer Control


NAS Security

P-GW


Packet Filtering

LTE

5G



Functional Split between NG-RAN and 5GC

internet

gNB or ng-eNB

RB Control


MeasurementConfiguration & Provision


AMF

UPF

Inter Cell RRM


NG-RAN 5GC

Mobility Anchoring


NAS Security

SMF


PDU Session Control

PDU Handling

internet

eNB

RB Control


eNB MeasurementConfiguration & Provision


PDCP

PHY

MME

S-GW

S1MAC

Inter Cell RRM


RLC

E-UTRAN EPC

RRC

Mobility Anchoring

EPS Bearer Control


NAS Security

P-GW


Packet Filtering

LTE

5G



Control Plane: 3GPP services (AAA, Mobility, Call control, QoS, etc.)User Plane: data and additional (application-specific, network agnostic) service signaling

Source: E. Guttman: System and Core Network Aspects. Workshop on 3GPP Submission towards IMT-2020, Oct. 2018

Service Based Architecture – User Plane5G Architecture – Control-User Plane Split


Technologies: Orchestration and Virtualization: Decouple logical function from HW Slicing: Logical end-2-end networks tailored to customer needs Mobile Edge Computing (MEC): Resources where they are needed (URLLC) Service Based Architecture: stateless, open, flexible Access agnostic solutions

Service Based Architecture – User Plane5G Service Based Architecture

Control plane

User plane


UPF (User Plane Function): packet routing & forwarding, packet inspection, QoS handling external PDU session point of interconnect to Data Network (DN) anchor point for intra- & inter-RAT mobility

Source: TS25.301: System Architecture for the 5G System (Stage 2)

Service Based Architecture – User PlaneService Based Architecture – User Plane

User plane


Protocol Architecture – User Plane

Source: TS 23.501: Systems Architecture for the 5G System (Stage 2)

5G-AN Protocol

Layers

L1

5G-ANProtocolLayers

L2

UDP/IP

GTP-U

PDU Layer

Application

Relay

L1

L2

UDP/IP

GTP-U

L1

L2

UDP/IP

GTP-U

PDU Layer

L1

L2

UDP/IP

GTP-U

Relay

UE 5G-AN UPF UPF(PDU Session Anchor)

N3 N9 N6

gNB

PHY

UE

PHY

MAC

RLC

MAC

PDCPPDCP

RLC

SDAPSDAP


Control Plane provides a set of Network Functions (NFs) with service-based interfaces which can be accessed by any other authorized NF

Service Based Architecture – Control Plane

Control plane


AMF (Access and Mobility Management function ≈ MME): termination of NAS signaling (N1) NAS ciphering & integrity protection registration management connection management mobility management access authentication and authorization security context management

SMF (Session Management function): session management UE IP address allocation, DHCP

functions termination of NAS signaling

related to session management DL data notification traffic steering configuration for

UPF (N4)

AUSF (Authentication Server Function ≈ HSS/AuC)



[7]

PCF (Policy Control Function ≈ PCRF): policy framework, providing policy rules to C plane functions access subscription information for policy decisions in UDR (Unified Data

Repository)AF (Application Function ≈ AF in EPC): application influence on traffic routing accessing NEF (Network Exposure Function, i.e. signaling GW) interaction with policy framework for policy controlUDM (Unified Data Management ≈ HSS): generation of Authentication and Key Agreement (AKA) credentials user identification handling, access authorization & subscription management



[7]

New Functions:NSSF (Network Slice Selection Function): selecting of the Network Slice instances to serve the UE determining the allowed NSSAI (Network Slice Selection Assistance Information)

slice/service type (SST) slice differentiator (SD) to differentiate among slides of the same type

determining the AMF set to be used to serve the UENEF (Network Exposure Function): exposure of capabilities and events, secure provision of information from external

application to 3GPP network, translation of internal/external informationNRF (NF Repository Function): service discovery function, maintains NF profile and available NF instances



Mobility Management, Connection Management and RRC States

MM states: deregistered registered

CN (Core Network) states: idle connected

RRC states: Idle: no context in gNB, cell reselection and TAI updates, TA paging Inactive (new): context in gNB, cell reselection and RAN updates, RAN paging Connected: context in gNB, handovers

For details on RRC Protocol, RRC states and transitions see TS 38.331 For comparison with LTE see Junseo Kim, Dongmyoung Kim, Sunghyun Choi: 3GPP SA2 architecture and

functions for 5G mobile communication system, ICT Express, Volume 3, Issue 1, March 2017, Pages 1-8

MM-DEREGISTERED CN-IDLE

RRC-IDLE

MM-REGISTERED CN-IDLE

RRC-IDLE

MM-REGISTERED CN-CONNECTED

RRC-CONNECTED

RRC-INACTIVE

CONNECTED


Mobility Management – Inter-gNB Handover Procedure

Source: TS 38.300, V 15.2.0: NR; NR and NR-RAN Overall description (Stage 2)

Target gNB

4. Handover Complete

Source gNB

AdmissionControl

2. Handover Acknowledgement3. Handover Command

UE

Switch to New Cell

1. Handover Request

1. Source gNB initiates handover and issues a Handover Request over the Xn interface2. Target gNB performs admission control and provides the RRC configuration as part of the Handover

Acknowledgement3. Source gNB provides the RRC configuration to the UE in the Handover Command (cell ID, information

required to access the target cell so that the UE can access the target cell without reading system information

4. UE moves the RRC connection to the target gNB and replies the Handover CompleteHandover mechanism triggered by RRC requires UE to reset the MAC entity and re-establish RLC and PDCP


Mobility Management in RRC Inactive State

RRC Inactive State: UE context stays in last serving gNB Transferred towards current gNB in case of transition to RRC connected state

Network-triggered Transition from RRC-Inactive to RRC-Connected

Last serving gNB gNB AMF

2. RAN Paging

UE

UE in RRC_INACTIVE / CM-CONNECTED

1. RAN Paging trigger

4. Resuming from RRC_INACTIVE

3. Paging the UE (Editor’s Note: details FFS)

Source: TS 38.300, V 15.2.0: NR; NR and NR-RAN Overall description (Stage 2)


Radio Access Protocols – User Plane

Segm.ARQ

Multiplexing UE1

Segm.ARQ...

HARQ

Multiplexing UEn

HARQ

Scheduling / Priority Handling

Logical Channels

Transport Channels

MAC

RLC Segm.ARQ

Segm.ARQ

PDCPROHC ROHC ROHC ROHC

Radio Bearers

Security Security Security Security

...

RLC Channels

SDAP QoS flowhandling

QoS Flows

QoS flowhandling

Multiplexing

...

HARQ

Scheduling

Transport Channels

MAC

RLC

PDCP

Segm.ARQ

Segm.ARQ

Logical Channels

RLC Channels

ROHC ROHC

Radio Bearers

Security Security

SDAP

QoS Flows

QoS flowhandling

Downlink Uplink



PDCP, RLC, MAC (compared to LTE)

PDCP:• Simplified, streamlined• Always reordering, or out of

sequence delivery (if configured)• Packet duplication

MAC:• Optimized PDU structure• Flexible HARQ support• Logical channel prioritization rules

for numerology, cell, etc.• SR, BSR specific rules for URLLC• 2x semi-persistent scheduling• On-demand system information

RLC:• No concatenation• Pre-processing of PDUs before

grant is available• Always out of sequence delivery• Simplified segmentation

gNB

PHY

UE

PHY

MAC

RLC

MAC

PDCPPDCP

RLC

SDAPSDAP

Simplified protocols for faster processing and higher flexibility

SDAP:• Flexible mapping of QoS flows

to data radio bearers (DRBs) according to QoS requirements


Added SDAP sublayer to offers QoS flows to 5G Core Network

Service Data Adaptation Protocol (SDAP)

Sources: • TS 38.300: NR; NR and NR-RAN Overall description (Stage 2)• TS 37.324: E-UTRA and NR; Service Data Adaptation Protocol (SDAP) specification

PDU Session

SDAP sublayer

PDCP sublayer

SDAP - PDU

PDCP - SDU

SDAP-SAP SDAP-SAP

...

SDAP entity SDAP entity

Radio Bearers

PDCP entity

PDCP entity

PDCP entity

PDCP entity

...

PDCP-SAP PDCP-SAP

...

QoS Flows

PDU Session

...

QoS Flows

• Marking of QoS flow ID in both DL and UL• QoS Flow Index (QFI) for both UL and DL packets

• explicit configuration• reflective mapping

Flexible mapping of QoS flows to data radio bearers (DRBs)

⇒ Highly specific handling of packets in PDCP, RLC, MAC and PHY layers to adapt to specific service demands


Quality of Service

P-GWS-GW PeerEntity

UE eNB

EPS Bearer

Radio Bearer S1 Bearer

End-to-end Service

External Bearer

Radio S5/S8

Internet

S1

E-UTRAN EPC

Gi

E-RAB S5/S8 Bearer

LTE

NR UPFNBUE

PDU Session

Radio NG-U

NG-RAN 5GC

Radio Bearer NG-U TunnelQoS Flow

QoS Flow

Radio BearerQoS Flow

Source: http://std-share.itri.org.tw/Content/Files/Event/Files/4.%20From%20LTE%20to%205G%20NR_ASUSTeK_v4.2.ppt

EPS Bearer turns into QoS Flow flexible mapping of QoS flows

on underlying bearers by SDAP, e.g. radio bearers suited to specific service (low frequency band to URLLC, mmWave freq. to eMMB)


URLLC: Higher Reliability requirements (1-10-6 to 1-10-9) Low latency (< 0.5ms in RRC connected state)

Control Plane implemented by Master Node (MgNB) User Plane: leveraging radio resources across MgNB and Secondary Node (SgNB)

PDCP

RLC

MAC

PHY

PDCP

MgNB SgNB

RLC

MAC

PHY

Packet Duplication

Single/Multi-shot transmission –repetition, Fast HARQ, Flexible

BLER, Different CQI to MCS table, LCP Restriction of numerology,

UL/DL Preemption

Larger SCS, low code rate, mini-slot, larger bandwidth, front

loaded DMRS

5G Solutions for URLLC

Ultra Reliable Low Latency Communications (URLLC)


Packet Duplication in PDCP to increase reliability of Signaling Radio Bearer (SRB) and Data Radio Bearer (DRB) for URLLC

Note that buffering and reordering in RLC does not make sense for duplicated packets!

Carrier Aggregation (same cell)

Dual Connectivity(different cells and possibly carriers)

URLLC – Packet Duplication


Cell1 Cell1

PDCPData

Data Data

RLC RLC

MAC

Data Data

PDCPData

Data

RLC RLC

MAC

PDCPData

Data Data

RLC RLC

MAC

Data Data

PDCPData

Data

RLC RLC

MAC MAC MAC

Cell2


Logical channel prioritization: map logical channels to MAC PDUs for transmission

Logical channel 1:- Priority 1 (high)

Logical channel 2:- Priority 2 (low)

LC1 LC2

Grant

LC1 LC2

MAC PDU

LCP

URLLC – Logical Channel Prioritization (LCP) in LTE



For achieving URLLC service requirements with latency ≦ 0.5ms Multiple numerologies/TTI (Transmission Time Interval) durations used

Logical channel scheduling limitations Sub-Carrier Spacing (SCS) Time information

Logical channel 1:- Priority 1 (high)- SCS index 1 (time)

Logical channel 2:- Priority 2 (low)- SCS index 2 (bandwidth)

LC1 LC2

Grant on SCS 2

LC1 LC2

MAC PDU

LCP

URLLC – LCP Enhancement in NR



μ No. of slots per subframe

015 KhHz

1(1 slot x 1ms = 1ms)

130 KhHz

2(2 slots x 500 μs = 1ms)

260 KhHz


3120 KhHz


4240 KhHz

16(16 slots x 62.5 μs = 1ms)

5480 KhHz

32(32 slots x 31.25 μs = 1ms)

URLLC – NR Sub-Carrier Spacing (SCS) and Slot length

Source: http://www.sharetechnote.com/html/5G/5G_FrameStructure.html

Time vs. bandwidth


5G radio frame: 10ms 1 Subframe: 1ms

NR provides slot based scheduling, each slot has 14 OFDM symbols Mini-slot scheduling with 2, 4 or 7 OFDM symbols (Shortening-TTI)

1ms Subframe

0.250ms Subframe (14 OS)



Mini-slot scheduling (2, 4 or 7 OFDM symbols)

URLLC – NR Frame Structure for Low Latency


Scheduling Request (SR) is for UE to autonomously request resources on data channel

Multiple SR configurations associated with different resource demands to achieve lower latency

SR configuration 1 SR1 SR1 SR1

SR configuration 2 SR2 SR2 SR2 SR2 SR2

UE BSSR

Uplink grant

BSR+data

UE BSSR1 / SR2

Uplink grant1/grant2

BSR+data1/data2

URLLC – Scheduling Request Enhancement

BSR: Buffer Status ReportSource: http://std-share.itri.org.tw/Content/Files/Event/Files/4.%20From%20LTE%20to%205G%20NR_ASUSTeK_v4.2.ppt


Scheduling of Resources (MAC Layer)

Source: FANTASTIC-5G: Final results for the flexible 5G air interface multi-node/multi-antenna solution, Public Deliverable D4.2, April 2017

Factors influencing packet scheduling:- UE: QoS requirements, buffer states, HARQ mode, link state, UE capabilities- Cell configuration: carrier config., ICIC config., reserved channels capacity


MR-DC is a generalization of the Intra-E-UTRA Dual Connectivity where a multiple Rx/Tx UE may be configured to utilize resources provided by two different nodes, one providing E-UTRA access and the other one providing NR access

One is Master Node and other is the Secondary Node MR-DC with the EPC MR-DC with the 5GC (not shown)

E-UTRA-NR Dual Connectivity NR-E-UTRA Dual Connectivity

en-gNB

eNB

S1-U

S1 S1

X2

E-UTRAN

EPC

MME/S-GW

en-gNB

eNB

S1-U

S1 S1X2

MME/S-GW

X2

X2-U

S1-U S1-U

Multi-RAT Dual Connectivity (MR-DC)

Source: 3GPP TS 38.300 V 15.2.0


5G Literature

Books on 5G P. Marsch, Ö. Bulakci, O. Queseth, M. Boldi: “5G System Design – Architectural

and Functional Considerations and Long Term Research,”, Wiley, June 2018 E. Dahlman, S Parkvall, J. Skold: “5G NR: The Next Generation Wireless Access

Technology,“ Academic Press, August 2018 Afif Osseiran, Jose F. Monserrat, Patrick Marsch: “5G Mobile and Wireless

Communications Technology,” Cambridge University Press, June 2016

More information on 5G 3GPP 5G – Briefing for Evaluation Groups, Oct. 2018: http://www.3gpp.org/news-

events/3gpp-news/1987-imt2020_workshop RWS-180006: mIoT, URLLC RWS-180007: NR Phy, channels, etc RWS-180009: NR architecture, SA/NSA, CP-UP split, gNB vs. ng-eNB, deployment

options RWS-180010: Air IF protocol architecture, protocols, RRC states, procedures

http://www.3gpp.org/news-events/3gpp-news/1987-imt2020_workshop

Documents

Applications & requirements Concepts Architecture …...SDN and NFV provide means to fulfill future requirements of 5G architecture Open interfaces To help integrate different components