5G Ultra-Reliable and Low Latency Communications

Transcription

1 5G Ultra-Reliable and Low Latency Communications Dr. Joachim Sachs, Principal Researcher, Ericsson Research 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 1

2 wireless access generations The foundation of mobile telephony Mobile telephony for everyone The foundation of mobile broadband The evolution of mobile broadband Non-limiting access anywhere, anytime, anyone, anything ~1980 ~1990 ~2000 ~2010 ~2020 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 2

3 Transformation Traditional Industries Digitize & Mobilize Transformed Industries Cloud Network Devices Applications 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 3

4 5G classes of use cases Massive MTC Critical MTC SMART BUILDING LOGISTICS, TRACKING AND FLEET MANAGEMENT TRAFFIC SAFETY & CONTROL SMART METER SMART AGRICULTURE CAPILLARY NETWORKS Enhanced Broadband INDUSTRIAL APPLICATION & CONTROL REMOTE MANUFACTURING, TRAINING, SURGERY LOW COST, LOW ENERGY SMALL DATA VOLUMES MASSIVE NUMBERS Smartphones Home, Enterprise, Venues, Mobile/Wireless/Fixed ULTRA RELIABLE VERY LOW LATENCY VERY HIGH AVAILABILITY Non-SIM devices 4k/8k UHD, Broadcasting, VR/AR, 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 4 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB

5 Critical Machine-Type Communication UlTra-reliable low latency communication Factory Automation 1 ms Motion Control 1 ms Remote Control ms Intelligent Transportation Systems 5 ms Smart Grid 3-5 ms Tactile Internet 1 ms Process Automation 100 ms Automated Guided Vehicle ms Numbers are examples, requirements vary within one application area 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 5

6 5G Radio Access Evolution of existing technology + New radio-access technology Evolution of LTE Backwards compatible Tight interworking NR No compatibility constraints Existing spectrum New spectrum 1 GHz 3 GHz 10 GHz 30 GHz 100 GHz 1 GHz 3 GHz 10 GHz 30 GHz 100 GHz Below 6 GHz Above 6 GHz New spectrum below 6 GHz 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 6 16

7 5G Radio Access Evolution of existing technology + New radio-access technology Evolution of LTE Backwards compatible Tight interworking NR No compatibility constraints Existing spectrum New spectrum 1 GHz 3 GHz 10 GHz 30 GHz 100 GHz 1 GHz 3 GHz 10 GHz 30 GHz 100 GHz Below 6 GHz Above 6 GHz New spectrum below 6 GHz Spectrum flexibility: licensed, licensed shared, unlicensed FDD, (dynamic) TDD, Full duplex 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 7 16

8 5g timeplan ITU IMT-2020 Requirements Proposals Specifications 3GPP 5G Study Item NR Phase 1 NR Phase 2 LTE evo LTE evo LTE evo Rel-14 Rel-15 Rel G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 8

9 NR Key technology features Flexible, scalable and future-proof design Ultra-lean design Deployment Spectrum Use cases Minimize network transmissions not directly related to user data delivery OFDM-based physical layer Massive beam-forming Multi-site coordination/connectivity System control Separate system-access functionality User data Access/backhaul integration Integrated D2D connectivity 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 9 19

10 Waveform LTE to NR LTE LTE downlink Conventional OFDM Fixed numerology Uplink DFT precoding for low PAR (enhanced PA efficiency / extended range) LTE uplink NR Conventional OFDM is baseline Flexible/scalable numerology (sub-carrier spacing, CP, TTI) Windowing for enhanced spectral confinement for uplink and downlink Means for low-par transmission (e.g. DFT precoding) for uplink and downlink NX downlink and uplink Scalable numerology 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 10

11 Scalable numerology Lower-frequency/wide-area deployments Higher-frequency deployments with less time dispersion Millimeter wave Frequency domain Time domain Larger sub-carrier spacing at higher frequencies Robust to higher phase noise Larger CP for lower frequencies To handle larger time dispersion in wide-area deployments on lower frequencies Shorter symbol time at higher frequencies Potential for even lower latency 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 11

12 NR Scalable numerology Sub-carrier spacing 15 khz 30 khz 60 khz 120 khz Cyclic prefix (µs) 4.7 µs 2.4 µs 1.2 µs 0.6 µs Subframe [ms] 500 µs 250 µs 125 µs 67.5 µs Symbols per subframe G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 12

13 Windowed OFDM Post-IFFT windowing reduces sub-carrier sidelobes Enhanced spectrum confinement Similar to Filtered OFDM but less complex and higher flexibility Without windowing With windowing -20 Enables mix of numerologies within one carrier For services with different requirements Windowing on TX and RX side db MHz 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 13

14 Fdd latency summary UE BS FDD Uplink New data SR Subframe duration Scheduling Option Optimistic processing Pessimistic Processing SG 500 us Dynamic 1.5 ms 2 ms 500 us Instant Uplink Access 1 ms 1 ms Data 250 us Dynamic 0.75 ms 1 ms SG 250 us Instant Uplink Access 0.5 ms 0.5 ms 125 us Dynamic ms 0.5 ms Data 125 us Instant Uplink Access 0.25 ms 0.25 ms 62.5 us Dynamic ms 0.25 ms 62.5 us Instant Uplink Access ms ms UE BS Data Available FDD Downlink Subframe duration Scheduling Option Optimistic processing Pessimistic Processing New data IUA grant Data 500 us n/a 1 ms 1 ms 250 us n/a 0.5 ms 0.5 ms SG 125 us n/a 0.25 ms 0.25 ms Data 62.5 us n/a ms ms Data Available 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 14

15 Fdd latency summary UE BS FDD Uplink Subframe duration Scheduling Option Optimistic processing Pessimistic Processing 500 us Dynamic 1.5 ms 2 ms Ultra-reliable and low latency communication 500 us Instant Uplink Access 1 ms 1 ms 250 us Dynamic 0.75 ms 1 ms New data SR SG Data SG 250 us Instant Uplink Access 0.5 ms 0.5 ms 125 us Dynamic ms 0.5 ms 125 us Instant Uplink Access 0.25 ms 0.25 ms 62.5 us Dynamic ms 0.25 ms 62.5 us Instant Uplink Access ms ms FDD Downlink Subframe duration Scheduling Option But latency is not sufficient! It is also about reliability. Optimistic processing Pessimistic Processing 500 us n/a 1 ms 1 ms 250 us n/a 0.5 ms 0.5 ms 125 us n/a 0.25 ms 0.25 ms New data UE Data IUA grant Data SG Data BS Data Available 62.5 us n/a ms ms Data Available 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 15

16 reliability (Ultra-) reliability Providing with high level of certainty that a message is correctly delivered to the receiver within a latency bound CDF [%] 100-ε Focus on the percentile Failure if Message is lost Message is too late Message has residual errors Guaranteed latency [ms] ε can be or even 10-9 (e.g. factory automation) 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 16

17 Reliable Real-Time : Example Factory automation Manufacturing cell with central controller communicating with sensors and actuators Wireless communication enables more flexible configuration of manufacturing cells and communication with moving parts Combination of high reliability and low latency not achievable with current wireless standards Characteristics Maximum end-to-end latency [ms] Motion control Alarms 0.5 to 1 1 Jitter [us] <1 Packet size [bytes] 10 to 16 2 to 10 Packet loss rate Application availability 99,999 % based on fixed links Small message sizes Periodic traffic Time-triggered data generation (e.g. real time motion control) Sporadic traffic and alarms Event-triggered data generation 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 17

18 Latency Budget Device processing Base station & controller processing Transmitter Base Station Sensor Actuator Receiver 100 µs transmission time Controller 1 ms total latency 100 µs transmission time (i.e. 10 th of the end-to-end delay budget) Guarantee for successful in-time delivery (reliability) 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 18

19 Cost of Guaranteeing high Reliability 10 0 Rayleigh fading channel 10-2 High reliability (e.g ) db fading marging CDF db Fading Gain (db) 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 19

20 Redundancy through diversity Rayleigh fading channel Diversity may be obtained through spatial diversity, and frequency diversity Time diversity difficult due to latency constraint Coding needed to fully exploit frequency and transmit diversity CDF Div Order = 1 Div Order = 2 Div Order = 4 Div Order = 8 Div Order = db 18 db Fading Gain (db) Diversity is key for ultra-reliable communications 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 20

21 Coding & Modulation Coding scheme Block code for packets < 10 bits Convolutional code for packets up to a few hundred bits Code rate Rate 1/2 1/3 good for performance-bandwidth tradeoff Minimum distance needs to be greater than diversity order Higher order modulation For devices with good SNR for bandwidth efficiency To keep code rate low for reliability Maximum order limited by transmitter and receiver impairments (EVM) Required received signal power (dbm) bit packet in 0.1 ms, 1x8 antennas BPSK QPSK 16QAM 64QAM 256QAM rate 1 rate 1/2 rate 1/ Minimum bandwidth (MHz) 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 21

22 Frame Structure Latency: access slots 0.1 ms Frame structure enabling low scheduling latency Slot formatting enabling low processing delay and on-the-fly decoding No computationally intensive receiver operation access slot access slot access slot access slot access delay data arrival RS Ctrl Data Traffic handling: support both periodic and sporadic traffic types Persistent scheduling for periodic traffic Dynamic scheduling or contention-based access for sporadic traffic All with high reliability and low latency 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 22

23 Multi-Connectivity for high Reliability Robust connectivity via coordinated multipoint communication via multiple sites across multiple frequency layers Fallback to other RATs (e.g. LTE) 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 23

24 Flexible Network Architecture Network layout for optimized service performance E.g. local functionality for delay optimization C-MTC device C-MTC appl. C-MTC appl. VNF VNF VNF VNF Distributed Data Center Central Data Center Network Slicing Distributed Cloud Virtualization VNF VNF Software Defined Networking (SDN) 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 24

25 5G Network evolution common network for many industries Critical communications < 5ms E2E delay % transmission reliability 500 Kmph relative velocity Massive communications > 10 years battery lifetime > 80% cost reduction 20dB better coverage 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 25

26 Summary ICT is an enabler for industry transformation based on digitized processes Cellular communications provides ubiquitous connectivity and broad capabilities One area is ultra-reliable and low latency communication (or critical machine-type communication) Technology components for ultra-reliable and low latency communication Diversity in space and frequency and robust coding for reliability Frame format for short delay and on-the-fly processing Flexible network architecture for service-optimized network design and deployment Ultra-reliable wireless transmission within 1ms latency is possible 5G standardization in 3GPP has started 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 26

27 REferences E. Dahlman, G. Mildh, S. Parkvall, J. Peisa, J. Sachs, Y. Selén and J. Sköld, "5G Wireless Access: Requirements and Realization," IEEE Communications Magazine, vol. 52, no. 12, Dec Ericsson, 5G - key component of the Networked Society, RWS , 3GPP RAN Workshop on 5G Phoenix, AZ, USA, September 17 18, O. N. C. Yilmaz, Y.-P. E. Wang, N. A. Johansson, N. Brahmi, S. A. Ashraf and J. Sachs, Analysis of Ultra-Reliable and Low-Latency 5G Communication for a Factory Automation Use Case, in IEEE ICC, London, Jun N. A. Johansson, Y.-P. E. Wang, E. Eriksson and M. Hessler, Radio Access for Ultra-Reliable and Low-Latency 5G Communications, in IEEE ICC, London, Jun J. Sachs, P. Popovski, A. Höglund, D. Gozalvez-Serrano and P. Fertl, Machine-Type Communications, book chapter in 5G Mobile and Wireless Communications Technology, ISBN , 2016, S. A. Ashraf, F. Lindqvist, B. Lindoff, R. Baldemair, "Control Channel Design Trade-offs for Ultra-Reliable and Low-Latency Communication System", IEEE Globecom Workshop on Ultra-Low Latency and Ultra-High Reliability in Wireless Communication, San Diego, USA, December, N. Brahmi, O. N. C. Yilmaz, K. W. Helmersson, S. A. Ashraf, J. Torsner, "Deployment Strategies for Ultra-Reliable and Low-Latency Communication in Factory Automation", IEEE Globecom Workshop on Ultra-Low Latency and Ultra-High Reliability in Wireless Communication, San Diego, USA, December, A. Osseiran, J. Sachs, M. Puleri, Manufacturing Rengineered: robots, 5G and the industrial internet, Ericsson Business Review, no. 4, 2015, J. Torsner, K. Dovstam, G.Miklós, B. Skubic, G. Mildh, T. Mecklin, J. Sandberg, J. Nyqvist, J. Neander, C. Martinez, B. Zhang, J. Wan, Industrial RemoteOperation: 5G rises to the challenge, Ericsson Technology Review, vol. 92, 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB Page 27 5G Ultra-Reliable and Low Latency Communication IEEE Communications Theory Workshop Ericsson AB

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