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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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
› 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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
Gigabit LTE (TDD, FDD, LAA)
Massive MIMO
Network Slicing
Dynamic service orchestration
Predictive analytics
5G NR
RAN virtualization
Federated network slicing
Distributed Cloud
Real time Machine learning/AI
TECHNOLOGIES
Multi-standard networks
Cloud optimized network functions
VNF orchestration
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
Gigabit LTE (TDD, FDD, LAA)
Massive MIMO
Network Slicing
Dynamic service orchestration
Predictive analytics
5G NR
RAN virtualization
Federated network slicing
Distributed Cloud
Real time Machine learning/AI
TECHNOLOGIES
Multi-standard networks
Cat-M1/NB-IoT
Cloud optimized network functions
VNF orchestration
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
› 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)
30 kHz 33.33 µs 2.38 µs 250 µs (7s) or 500 µs (14s)
60 kHz 16.67 µs 1.19 µs 125 µs (7s) or 250 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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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)
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
› 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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
› 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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
› 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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
› 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
30kHz, 2s (mini-slot) 286 µs 500 µs +n * 214 µs
60kHz, 2s (mini-slot) 161 µs 268 µs +n * 107 µs
120kHz, 2s (mini-slot) 89 µs 143 µs +n * 54 µs
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
› 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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
› 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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
Cost of reliability?
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14
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
Joachim Sachs: 5G Ultra-Reliable and Low Latency Communication | EUCNC 2017 | © Ericsson AB 2017 | 2017-06-14