5g techniques for ultra reliable low latency...

Dr. Janne PeisaPrincipal Researcher, Ericsson Research

5G Techniques for Ultra Reliable Low LatencyCommunication

Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14

SMART

AGRICULTUREFLEET

MANAGEMENT

SMART

METER

LOGISTICS

TRACKING

TRAFFIC SAFETY

& CONTROL

INDUSTRIAL

APPLICATION &

CONTROL

REMOTE

TRAINING

REMOTE

MANUFACTURING REMOTE

SURGERY

SMARTPHONESHOME

NON-SIM

DEVICES

ENTERPRISE

VENUES

MOBILE/

WIRELESS/

FIXED

4K/8K UHD

BROADCASTING

VR/AR

5G is use case driven

LOW COST, LOW ENERGY

SMALL DATA VOLUMES

MASSIVE NUMBERS

ULTRA RELIABLE

VERY LOW LATENCY

VERY HIGH AVAILABILITY

Critical MTCMassive MTC

Enhanced mobile broadband


Use case evolution with supporting technology

Multi-standard network

Cat-M1/NB-IoT

Cloud optimized network

functions

VNF orchestration

Gigabit LTE (TDD, FDD, LAA)

Massive MIMO

Network Slicing

Dynamic service orchestration

Predictive analytics

5G NR

Virtualized RAN

Federated network slicing

Distributed Cloud

Real time machine learning/AI

Screens

everywhere

Immersive

experience8K

AR

4KVR

On demand

information

Autonomous

control

Technologies

On the road to 5G 5G experienceCurrent

Connected

doctors

and patients

Remote

operations

Process

automation

Cloud robotics and

remote control

Metering and

smart grid

Machine intelligence

and real-time control

Manufacturing

Healthcare

Energy & Utilities

Enhanced Mobile

Broadband

Automotive

AI

New toolsVR

Real-time information

vehicle to vehicle

Monitoring and

medication e-care

Flow management

and remote supervision

Resource management

and automation


SMART

AGRICULTUREFLEET

MANAGEMENT

SMART

METER

LOGISTICS

TRACKING

TRAFFIC SAFETY

& CONTROL

INDUSTRIAL

APPLICATION &

CONTROL

REMOTE

TRAINING

REMOTE

MANUFACTURING REMOTE

SURGERY

SMARTPHONESHOME

NON-SIM

DEVICES

ENTERPRISE

VENUES

MOBILE/

WIRELESS/

FIXED

4K/8K UHD

BROADCASTING

VR/AR

5G is use case driven

LOW COST, LOW ENERGY

SMALL DATA VOLUMES

MASSIVE NUMBERS

ULTRA RELIABLE

VERY LOW LATENCY

VERY HIGH AVAILABILITY

Critical MTCMassive MTC

Enhanced mobile broadband


C-MTC Use cases Latency & Reliability

E2E

Latency

Failure rate ()10-1 10-2 10-4 10-910-3 10-5 10-6 10-7 10-810-0

100ms

10ms

1ms

latency [ms]

Guaranteed

latency bound

CDF [%]

100-

50

The reliability is specified by the failure probability

ε of packets which are not successfully delivered

to the receiver within the latency bound, as they

are either erroneous, lost or arrive too late.

High reliability

ITS

Tactile Internet

Automated

Guided Vehicle

Remote

Control

Process

Automation

Factory Automation

Smart Grid


C-MTC Use cases Latency & Reliability

E2E

Latency

Failure rate ()10-1 10-2 10-4 10-910-3 10-5 10-6 10-7 10-810-0

100ms

10ms

1ms

e.g. smart grid

End-to-end latencyRAN latency &

reliability

3GPP/ITU target on RAN latency and reliability.

ITS

Tactile Internet

Automated

Guided Vehicle

Remote

Control

Process

Automation

Factory Automation

Smart Grid

3GPP/ITU

3GPP


› Predictive maintenance of vehicle

› Capturing sensor data for real-time traffic, weather, parking, and mapping services

On the road to 5G

› WiFi Hotspot

› On demand GPS map data

› Over-the-air software updates

Current

› Autonomous vehicle control

› Cooperative collision avoidance

› Vulnerable road user discovery

5G Experience (2021+)

Automotive use case Evolution


Automotive use case Requirements

On the road to 5GCurrent 5G Experience (2021+)

Coverage

Robust performance

Latency: 5ms

Availability: 99.999%

Reliability: 99.999%

Mobility: High

Reduced latency

High throughputTECHNICAL

REQUIREMENTS


Massive MIMO

Network Slicing



5G NR

RAN virtualization


Distributed Cloud

Real time Machine learning/AI

TECHNOLOGIES

Multi-standard networks

Cloud optimized network functions

VNF orchestration


Manufacturing use case evolution

On the road to 5G

› Intra-/inter enterprise communication

› Connected goods

Current 5G Experience (2022+)

› Collaborative robots

› Distributed control system

› Remote quality inspection

› Remote control of robots

› Augmented reality support in training, maintenance, construction and repair


Manufacturing requirements

On the road to 5GCurrent 5G Experience (2022+)

Coverage

Robust performance

Latency: Down to below 1ms

Reliability: Down to packet loss of less than 10-9

Reduced latency

High throughputTECHNICAL

REQUIREMENTS


Massive MIMO

Network Slicing



5G NR

RAN virtualization


Distributed Cloud

Real time Machine learning/AI

TECHNOLOGIES

Multi-standard networks

Cat-M1/NB-IoT

Cloud optimized network functions

VNF orchestration


5G: A network for the Networked Society

Transport

Access Applications

Cloud Infrastructure

Management

One architecture supporting multiple industries

END-USER

DATA RATES

10-100x

MOBILE DATA

VOLUMES

1000x

LOWER

LATENCY

5x

MORE

DEVICES

100x

DEVICE COST

REDUCTION

Cost

YEARS

BATTERY LIFE

10+

BETTER

COVERAGE

+20dB


3GPP 5g timeplan

Rel-15Rel-14 Rel-16

NR Study Item

NR WI Phase 1

SI Self-evaluation

LTE evo LTE evo LTE evo

Requirements ProposalsITU

3GPP

Specifications

2015 2016 2017 2018 2019 2020

IMT-2020

SI: Channel mod.

SI: Requirements

NR SIs Phase 2

NR

non-standalone

NR

standaloneFull IMT-2020

NR WIs Phase 2 NR evolution


5G Radio Access

Evolution of existing technology + New radio-access technology

NR

Tight

interworkingEvolution of LTE

1 GHz 3 GHz 10 GHz 30 GHz 100 GHz 1 GHz 3 GHz 10 GHz 30 GHz 100 GHz

No compatibility constraintsBackwards compatible

Spectrum flexibility: licensed, licensed shared, unlicensedFDD, TDD


NR – selected design targets

Beam centric

Multi-connectivity

Ultra-lean

Minimize network transmissions

not directly related to user-data delivery ?

Forward compatibility

Low latency

One slot

Mini-slot

Multi-service

Network Slices


› Based on OFDM

› Flexible/scalable numerology (sub-carrier spacing, CP, TTI)

› Windowing / filtering for enhanced spectral confinement

– Enables mixing of numerologies on the same carrier

– Compatibility with LTE-M / NB-IoT, sync signals

› Complementary DFT-precoding option for low PAPR in uplink

› Shorter slots / lower latency at higher numerologies

NR Waveform

Numerology Symbol Cyclic Prefix Slot duration / TTI

15 kHz 66.67 µs 4.76 µs 500 µs (7s) or 1000 µs (14s)



120 kHz 8.33 µs 0.59 µs 125 µs (14s)

240 kHz 4.17 µs 0.30 µs 63 µs (14s)

NX downlink and uplink

Scalable numerology

DFT IFFTCP

insertionWindowing


Numerology & Deployments

cell size

large

medium

small

low medium high frequency

Increasing numerology

due to phase noise

Decreasing

numerology due

to time dispersion

vs. cyclic prefix

(or extended

cyclic prefix)


Numerology & Deployments

Increasing numerology

due to phase noise

Decreasing

numerology due

to time dispersion

vs. cyclic prefix

(or extended

cyclic prefix)60 kHz

30 kHz

15 kHz

30 kHz

15 kHz

15 kHz

60 kHz

30 kHz

30 kHz

60 kHz

cell size

large

medium

small

low medium high

60 kHz

30 kHz

15 kHz

30 kHz

15 kHz

frequency

120 kHz


› Typical slots of 7 or 14 symbols

› Possibility of mini-slots

– Suitable for low latency transmission (URLLC)

– Can be punctured into other transmissions

– Efficient multiplexing of URLLC services with e.g. eMBB traffic

Slot Structures

14 symbols 14 symbols 14 symbols

var. length

var. start

mini-slot

Symbol CP Slot

15 kHz 66.67 µs 4.76 µs 1000 µs (14s)

30 kHz 33.33 µs 2.38 µs 500 µs (14s)

60 kHz 16.67 µs 1.19 µs 250 µs (14s)

120 kHz 8.33 µs 0.59 µs 125 µs (14s)

14 symbols 14 symbols


› Scheduling-request based uplink access

– Improved latencies and turn-around times due to very fast

processing in NR

› Grant-free uplink access

– Direct access to channel

› Provide configured transmission opportunities in uplink

› Avoids need for scheduling request and scheduling grant

› Preferably avoiding explicit time alignment (TA),

i.e. asynchronous access

– Provides similar latencies in uplink as in downlink

Fast Uplink Access

SR

SG

Data

UE BS

New data

data

delivered

TA

Grant-free data

configuration

Grant-free data

UE BS

New data

data

delivered


› General

– High numerologies for shorter slot lengths

– Mini-slots for e.g. low latency transmissions

– Fast processing

› Fast decoding for quick turn-around

› Enables fast HARQ and fast dynamic scheduling

› FDD

– Can be specifically for URLLC

› TDD

– Frequent change of UL-DL allocations needed

› Trade-off of slot length vs. switching overhead

– Fast processing / turn-around

NR Techniques for Low Latency

x1

slot slot

mini-slot

x4

RX TXFast HARQ

Fast dynamic scheduling

turn-around

FDD Uplink

› mini-slots

› instant uplink access

› fast processing / turn-around

FDD Downlink

› mini-slots

› fast processing /

turn-around

TDDDL

UL


› Latencies depend on NR configurations

– numerology

– slot structure

– uplink access scheme

› Latencies assumed with worst-case

timing (“what can be guaranteed”) but

assuming fast NR processing

Example NR RAN Latencies

TDD DL & grant-

free UL

SR-based

UL

Retx delay

30kHz, 7s 1071 µs 2321 µs +n * 1250 µs

60kHz, 7s 554 µs 1179 µs +n * 625 µs

120kHz, 14s 536 µs 1161 µs +n * 625 µs

FDD DL & grant-

free UL

SR-based

UL

Retx delay

15kHz, 7s 1643 µs 3143 µs +n * 1500 µs

15kHz, 2s (mini-slot) 571 µs 1000 µs +n * 429 µs

30kHz, 7s 821 µs 1571 µs +n * 750 µs





› Exploit all diversity levels

– Multi-antenna: diversity coding over all antenna elements / sites

– Frequency: send over wide bandwidth

› Robust coding and modulation (MCS selection) ( )

– Select a very low code rate and low modulation constellation order

› For a given SINR, the MCS should provide very low BLER

› Robust channel (state) estimation ( )

– Extra robust channel estimation, in particular for low SINR

– Margin for channel estimation error

› Multi-connectivity on different frequencies (RATs)

– Intra-site or inter-site

› Constant connectivity during mobility

Techniques for High reliability at low Latency

SINR

Spectral efficiency

MBB

URLLC


› One-shot transmission

– Use low code rate to obtain low error

low efficiency, and requires robust

control

› Many-shot transmissions

– Repeat transmission of standard

reliability in time or frequency less

efficient, but less demanding

› Retransmission (HARQ-based)

– Repeat only when needed

– The more retransmissions possible the

higher code rate can be used

higher efficiency

How to reach reliability

Short latency req.

Relaxed latency req.

Processing,

alignmentProcessing

Processing

Low code rate

Repetitions

Retransmissions

(Rare) (Very

rare)

Retransmission, fast HARQ

Retransmission over longer period

Frequency

duplication

Allowing more retransmissions:

- Shorter TTI (mini-slots, numerology)

- Shorter processing & turnaround

- Relaxed latency requirement

Bandw

idth


Cost of reliability?


5g

• 5G will enable ultra-reliable and low latency

communication

• Low latency via flexible numerology, mini-slots,

grant-free instant uplink, fast processing

• High reliability via multi-connectivity, diversity

and robust PHY design

5g techniques for ultra reliable low latency...

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