overview low power wide area networks: an
TRANSCRIPT
Low Power Wide Area Networks: An Overview
U. Raza, P. Kulkarni, and M. Sooriyabandara, “Low power wide area networks: an overview,” IEEE Communications Surveys and Tutorials, vol. 19, no. 2, May 2017.
Presented by Peter Fitchen, Ricky Lin, Matthew Shannon
Contents1. Introduction
2. Design Goals & Techniques
3. Proprietary Technologies
4. Standards
5. Challenges & Research Directions
6. Conclusion
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Introduction: Research Motivation
● IoT market is growing
● 4.3 trillion dollars by 2024
● Improvements in cheap sensor and actuation technology
● Novel communication systems e.g. LPWA networks
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Introduction: Traditional IoT Communication
● Short-range wireless networks e.g. Zig-Bee, Bluetooth
● Legacy wireless local area networks e.g. Wi-Fi
● Cellular networks e.g. LTE
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Introduction: LPWA Characteristics
● Range from a few to 10s of kilometers
● Battery life of 10+ years
● Low cost
● Low data rate on order of 10 kbps
● High latency ranging from seconds to minutes
● Suitable for Massive MTC, not Critical MTC
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Design Goals & Techniques
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Design Goals & Techniques: Long Range
● Sub-1GHz band
● Modulation Techniques
○ Narrowband and Ultra Narrowband
○ Spread spectrum
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Narrowband signal
Adapted from: https://bit.ly/2Uu4ySG
Design Goals & Techniques: Low Power Cont
● Topologies: Star (sometimes tree and mesh)
● Duty cycling transceivers
● Lightweight Medium Access Control: CSMA/CA, ALOHA, and
TDMA-MAC
● Offloading capacity from end devices
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Design Goals & Techniques: Low Cost
● Star topology, simple MAC layers, offloading complexity
● Reduction in hardware complexity
● Minimum infrastructure
● Using license-free or owned licensed bands
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Design Goals & Techniques: Scalability
● Diversity techniques
● Densification
● Adaptive channel selection and data rate
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Design Goals & Techniques: QoS
● Diverse applications with varying requirements
● Limited to no QoS in current applications
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Proprietary Technologies
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Proprietary Technologies: Quick Definitions
● Unslotted/Slotted ALOHA
● Code Division Multiple Access (CDMA)
● Random Phase MA Direct Sequence Spread Spectrum (RPMA-DSSS)
● Binary Phase Shift Keying (BPSK)
● Gaussian Frequency Shift Keying (GFSK)
● Chirp Spread Spectrum (CSS)
● Service Level Agreement (SLA) support
● Time Difference of Arrival (TDOA)
● Link Budget
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Proprietary Technologies: Sub-GHz ISM Band
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Proprietary Technologies: SIGFOX
● Offers a proprietary end-to-end LPWA connectivity solution
● Base stations connected to backend via an IP-based network
● 360 UNB 100Hz channels in sub-GHz ISM band (868MHz, 902MHz)
● Star top. with unslotted ALOHA and BPSK(UL)/GFSK(DL) modulation
● 10km/50km (urban/rural), but bit rates are: 100bps(UL), 600bps(DL)
● Asymmetric bidirectional comm.: only 140(UL)/4(DL) messages per day
● Fixed data rate with 12B(UL) and 8B(DL) packets
● Can’t ACK every UL; no FEC, encryption, SLA support, or OTA updates
● UL reliability is improved with repeated message transmission16
Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Proprietary Technologies: LoRa
● Physical layer technology for symmetric bidirectional communication
● Sub-GHz ISM band operation (433MHz/868MHz, 915MHz, 430MHz)
● CSS and FEC give resilience to interference and noise, high link budget
● Tradeoff between range and data rate: up to 5km/15km, 0.3-37.5kbps
● Uses an unslotted ALOHA MAC layer, 64+8(UL)/8(DL) channels in US
● Star of stars top. allows for TDOA localization and higher reliability
● Supports up to 250B packets with AES 128b encryption
● Relatively high bidirectional data rate makes OTA updates possible
● No SLA support17
Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Proprietary Technologies: Ingenu RPMA
● Leverages regulations in 2.4GHz ISM band over sub-GHz properties
● Lack of limit on duty cycle enables higher throughput and capacity
● Uses patented RPMA-DSSS for UL to reduce overlapping transmissions
● Base stations use SS and CDMA for slightly asymmetric DL comm.
● Up to 78kbps(UL)/19.5kbps(DL) data rate and 15km (urban!) range
● Sends 10KB packets with 16B hash or AES 256b encryption and FEC
● Relatively high data rate allows for OTA firmware updates
● Network uses a star or tree topology, so localization is not possible
● No SLA support either18
Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Proprietary Technologies: TELENSA
● Telensa provides an end-to-end full network stack for third party apps
● Network consists of proprietary end devices and base stations
● Not much is publicly known about Telensa’s network implementation
● Uses a proprietary 2-FSK UNB mod. scheme in the sub-GHz ISM band
● Supports 62.5bps(UL)/500bps(DL) with a 1km urban range
● Unclear how many channels are used and what the MAC layer is
● Network uses a star topology, so device localization is not offered
● Only known packet detail is that FEC is used
● OTA firmware updates are available19
Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Proprietary Technologies: QOWISIO
● Similarly, Qowisio also offers a fully integrated solution to customers
● It combines LoRa with its own UNB technology
● Even less is known about Qowisio’s network
● Qowisio provides the end devices, manages the network
infrastructure, develops custom applications, and provides access at a
backend cloud for customers
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Proprietary Technologies: Comparisons
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Proprietary Technologies: Comparisons
● SIGFOX allows for really simple End Devices
● LoRa PHY allows for adaptable data rates for different ranges, uses
encryption and FEC, and can provide end device localization
● Ingenu’s proposed network uses the 2.4GHz band and offers a higher
bit rate and range combination, but likely isn’t as low cost or low power
● Telensa’s UNB proprietary network might offer a lower barrier to entry
for some urban applications, which is their current focus
● Qowisio offers a similar full stack solution to Telensa
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Standards
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Standards
● Institute of Electrical and Electronics Engineers (IEEE)
● European Telecommunications Standard Institute (ETSI)
● Third Generation Partnership Project (3GPP)
● Internet Engineering Task Force (IETF)
● Weightless-SIG
● LoRa Alliance
● DASH7 Alliance
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Standards: IEEE
● IEEE 802.15.4k (Low Energy, Critical Infrastructure Monitoring Networks)
● IEEE 802.15.4g (Low-Data-Rate, Wireless, Smart Metering Utility Networks)
● IEEE 802.11 (Wireless Local Area Networks)
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Standards: ETSI
● Low Throughput Network (LTN)
○ Support proprietary Ultra-narrow Band (UNB)
○ Use Orthogonal Sequence Spread Spectrum (OSSS) modulation schemes
○ Recommended modulation scheme:
■ BPSK in uplink and GFSK in downlink
■ Any OSSS for bidirectional communication
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Standards: 3GPP
● Enhanced Machine Type Communications (eMTC)
○ CAT 1 → CAT 0 → CAT M1
○ Power Saving Mode (PSM) & extended Discontinuous Reception (eDRx)
● Extended Coverage GSM (EC-GSM)
○ +20dB using the SUB-GHz band
● Narrow- Band IoT (NB-IoT)
○ Coexistence with GSM, GPRS, and LTE
○ 10 years battery life when transmitting 200 B/day
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Standards: IETF
● IPv6 stack for Low power Wireless Personal Area Networks (6LoWPAN)
● Full IPv6 stack for LPWA (6LPWA)
○ Header compression
○ Fragmentation and reassembly
○ Management
○ Security, integrity, and privacy
■ Symmetric key cryptography
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Standards: Weightless-SIG
● WEIGHTLESS-W
○ Operate in TV white spaces with 16-QAM and Differential-BPSK
● WEIGHTLESS-N
○ Operate in SUB-GHz bands with Differential-BPSK
○ One-way communication (end-device to base station)
● WEIGHTLESS-P
○ Operate in SUB-GHz ISM band using GMSK and QPSK
○ Full support of acknowledgements and bidirectional communication
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Standards: LoRa Alliance
● LoRaWAN
○ LoRa in PHY layer and ALOHA scheme in MAC layer
○ Backend system (brain of the LoRaWAN)
○ Classes of end-devices
■ Class A
● Longest lifetime but highest latency
■ Class B
● Schedulability of downlink reception
■ Class C
● Mains-powered
● Continuously listen and receive downlink transmission with shortest latency
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Standards: DASH7 Alliance
● DASH7 Alliance Protocol (D7AP)
○ Use two-level GFSK in SUB-GHz bands
○ Use tree topology by default
○ Force end devices to check channel periodically
○ Define complete network stack
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Challenges & Research Direction
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Challenges & Research Directions
● Scaling networks to massive number of devices
● Interference control and mitigation
● High data-rate modulation techniques
● Interoperability between different LPWA technologies
● Localization
● Link optimizations and adaptability
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Challenges & Research Directions (Cont.)
● LPWA testbeds and tools
● Authentication, Security, and Privacy
● Mobility and roaming
● Support for service level agreements
● Co-existence of LPWA technologies with other wireless networks
● Support for data analytics
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Conclusion
● Each of these networks are best suited for different applications
● Choice of technology and standard ultimately depend on business case
● Ongoing competition between LoRa, SIGFOX, INGENU, and main
cellular service companies
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Introduction
Design Goals & Techniques
Proprietary Technologies
Standards
Challenges & Research Directions
Conclusion
Questions?
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