Overview Low Power Wide Area Networks: An

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

2

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

3

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

4

Introduction



Standards


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

5

Introduction



Standards


Conclusion

6

Introduction



Standards


Conclusion


7

Introduction



Standards


Conclusion

Design Goals & Techniques: Long Range

● Sub-1GHz band

● Modulation Techniques

○ Narrowband and Ultra Narrowband

○ Spread spectrum

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Introduction



Standards


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



Standards


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

10

Introduction



Standards


Conclusion

Design Goals & Techniques: Scalability

● Diversity techniques

● Densification

● Adaptive channel selection and data rate

11

Introduction



Standards


Conclusion

Design Goals & Techniques: QoS

● Diverse applications with varying requirements

● Limited to no QoS in current applications

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Introduction



Standards


Conclusion


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Introduction



Standards


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



Standards


Conclusion

Proprietary Technologies: Sub-GHz ISM Band

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Introduction



Standards


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



Standards


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



Standards


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



Standards


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



Standards


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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Standards


Conclusion

Proprietary Technologies: Comparisons

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Introduction



Standards


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



Standards


Conclusion

Standards

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Introduction



Standards


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



Standards


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



Standards


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



Standards


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



Standards


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



Standards


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



Standards


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



Standards


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



Standards


Conclusion

Challenges & Research Direction

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Introduction



Standards


Conclusion


● 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



Standards


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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Standards


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



Standards


Conclusion

Questions?

36

Overview Low Power Wide Area Networks: An

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