Understanding the Limits of LoRaWAN

1 This work has been accepted for publication in IEEE Communications Magazine in January 2017 . Please, cite the IEEEC ommunications the Limits of LoRaWANF erran Adelantado, Xavier Vilajosana, Pere Tuset-Peiro, Borja Martinez, Joan Meli -Segu , Thomas Watteyne,ABSTRACTLow-Power Wide Area Networking (LPWAN) technologyoffers long-range communication, which enables new typesof services. Several solutions exist; LoRaWAN is arguablethe most adopted. It promises ubiquitous connectivity inoutdoor IoT applications, while keeping network structures,and management, simple.

2 This technology has received a lotof attention in recent months from network operators andsolution providers. Yet, the technology has limitations thatneed to be clearly understood to avoid inflated expectationsand disillusionment. This article provides an impartial andfair overview of what the capabilities and the limitations ofLoRaWAN are. We discuss those in the context of use cases,and list open research and development INTRODUCTIONN etwork operators are starting to deploy horizontal M2 Msolutions to cover a wide set of large scale verticals, using LowPower Wide Area Networking (LPWAN) technologies [1],[2].

3 Application domains include smart city, metering, on-street lighting control or precision agriculture. LPWAN tech-nologies combine low data rate and robust modulation toachieve multi-km communication range. This enables simplestar network topologies that simplify network deployment andmaintenance [3]. While the benefits of these technologies areknown and are often considered as the key enablers for someapplications, their limitations are still not well understood [4],[5].In this article we aim to provide an impartial overview ofthe limitations of LoRaWAN [6], one of the most successfultechnologies in the LPWAN space.

4 LoRaWAN is a networkstack rooted in the LoRa physical layer. LoRaWAN features araw maximum data rate of 27 kbps (50 kbps when using FSKinstead of LoRa), and claims that a single gateway can collectdata from thousands of nodes deployed kilometers away. Thesecapabilities have really resonated with some solution providersand network operators, who have created a large momentumbehind LoRaWAN to the point that it is sometimes touted asthe connectivity enabler for any IoT use case [7].The goal of this article is to bring some sanity to thesestatements, by providing a comprehensive, fair and inde-pendent analysis of what the capabilities and limitations ofLoRaWAN are.

5 We adopt a pragmatic approach, and identifyin which use cases the technology works, and in which usecases it doesn t work. Section II provides an overview ofLPWAN technologies, including cellular. Section III describesF. Adelantado, P. Tuset-Peiro, B. Martinez and J. Meli -Segu are with IN3at the Universitat Oberta de Vilajosana is with IN3 at Universitat Oberta de Catalunya and Watteyne is with Inria, EVA-team, Paris, technology in details. Section IV analyzes thenetwork capacity and scale limitations of the technology.

6 Sec-tion V discusses the use cases where LoRaWAN works/doesn twork. Section VI lists open research and development chal-lenges for the technology. Section VII OVERVIEW OFLPWANANDCELLULARTECHNOLOGIES FORIOTA. Low-Power Wide-Area AlternativesAlthough LoRaWAN is one of the most adopted technolo-gies for IoT, there is a wide range of LPWAN technologiesin the market, such as Ingenu, Weightless W, N and P orSigFox [8].Ingenu developed a proprietary LPWAN technology in GHz band, based on Random Phase Multiple Access(RPMA) to provide M2M industry solutions and privatenetworks.

7 The main asset of Ingenu in comparison withalternative solutions is high data rate up to 624 kbps in theuplink, and 156 kbps in the downlink. On the contrary, theenergy consumption is higher and the range is shorter (a rangearound 5-6 km) due to the high spectrum band Weightless Special Interest Group developed a set ofthree open standards for LPWAN: Weightless-W, Weightless-Nand Weightless-P. Weightless-W was developed as a bidirec-tional (uplink/downlink) solution to operate in TV whitespaces(470-790 MHz).

8 It is based on narrowband FDMA channelswith Time Division Duplex between uplink and downlink; datarate ranges from 1 kbps to 1 Mbps and battery lifetime isaround 3-5 years. Weightless-N was designed to expand therange of Weightless-W and reduce the power consumption (abattery lifetime up to 10 years) at the expense of data ratedecrease (from up to 1 Mbps in Weightless-W to 100 kbps inWeightless-N). Unlike Weightless-W, Weightless-N is basedon the Ultra Narrow Band (UNB) technology and operatesin the UHF 800-900 MHz band; it provides only uplinkcommunication.

9 Finally, Weightless-P is proposed as a high-performance two-way communication solution that can operateover 169, 433, 470, 780, 868, 915 and 923 MHz , cost of the terminals and power consumption arehigher than in Weightless-N, with a battery lifetime of with LoRaWAN , SigFox is one of the mostadopted LPWAN solutions. It is a proprietary UNB solutionthat operates in the 869 MHz (Europe) and 915 MHz (NorthAmerica) bands. Its signal is extremely narrowband (100 Hzbandwidth).

10 It is based on Random Frequency and TimeDivision Multiple Access (RFTDMA) and achieves a data ratearound 100 bps in the uplink, with a maximum packet payloadof 12 Bytes, and a number of packets per device that cannotexceed 14 packets/day. These tough restrictions, together [ ] 13 Feb 2017a business model where SigFox owns the network, have some-what shifted the interest to LoRaWAN , which is consideredmore flexible and Cellular solutions for IoTThe 3rdGeneration Partnership Project (3 GPP) standard-ized a set of low cost and low complexity devices target-ing Machine-Type-Communications (MTC)