An academic perspective on LoRaWAN. Fernando Kuipers Feb. 2 nd,

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1 An academic perspective on LoRaWAN Fernando Kuipers Feb. 2 nd,

2 Objective Highlights from the scientific literature Performance Collisions Simulators Improvements No details, but pointers 2

3 Performance 3

4 Spin the wheel! Doppler effect Frequency shift Source: [1]. Possible effect for SF12 at 38 km/h (doubles when SF is lowered) Corroborated by angular (rotating disk) and linear (car/boat) velocity experiments Coverage up to 30 km at sea [1] Petäjäjärvi et al., Performance of a low-power wide-are network based on LoRa technology: Doppler robustness, scalability and coverage, Int. J. of Distributed Sensor Networks, vol.13(3),

From the city to the mountains Vegetation matters 50-90m coverage in the forest Temperature matters High temperature has detrimental impact Source:

5 From the city to the mountains Vegetation matters 50-90m coverage in the forest Temperature matters High temperature has detrimental impact Source: [2]. Antenna matters [2] Iova et al., LoRa from the City to the Mountains: Exploration of Hardware and Environmental Factors, Proc. of EWSN,

6 to indoors SF7 SF9 Measurements at TU Delft, performed by my students Lichen Yao, Lu Liu, Xin Liu, and Minfeng Li. [3] Neumann et al., Indoor Deployment of Low-Power Wide Area Networks (LPWAN): a LoRaWAN case study, Proc. of IEEE WiMob,

7 LoRaWAN in the wild Generic devices Use default keys Do not need to registered device id or associated application Sent packets that are typically not encrypted Dec July 2016, all TTN data from nodes using generic key 2B7E151628AED2A6ABF CF4F3C Received frames 17,467,312 Unique frames 16,228,814 Unique device ids 1,618 Gateways 691 [4] N. Blenn and F.A. Kuipers, LoRaWAN in the Wild: Measurements from The Things Network, arxiv:

8 Results from the wild [4] device id s 1.2e+07 Spreading Factor 40 Frequency usage EU number of nodes that sent n packets 10 frequency 8e+06 4e+06 density e+01 1e+03 1e+05 packets sent (n) 0 SF7 BW125 SF8 BW125 SF9 BW125 SF11 BW125 SF12 BW500 SF7 BW250 SF8 BW500 SF10 BW125 SF12 BW frequency 8

9 Coffee time? [4] 10,104,330 readable strings 9

10 Collisions 10

11 Capture effect Depending on power & timing, one of multiple concurrent signals is received Source: [5] Bor et al., LoRa for the Internet of Things, Proc. of EWSN

12 Our additional experiments* Objective Scenario Evaluation Metrics Equal received power Frame collision characteristics Single gateway Different transmission powers Line-of-sight (LOS) Non-line-of-sight (NLOS) End-to-end packet delivery ratio (PDR) Signal quality (RSSI, SNR) Same Network Multiple gateways Different Networks * Experiments performed by my MSc student Andri Rahmadhani. 12

destroyed (LoRa header of the weaker frame

13 Frame loss conditions Both frames get destroyed (preamble lock) Weaker frame gets destroyed, stronger frame survives (LoRa header of the weaker frame gets destroyed, receiver immediately starts reading new frame) Both frames get destroyed (LoRa header of the weaker frame OK, keeps lock) Both frames get destroyed (MIC/Payload CRC error) 13

14 Simulators 14

Simulating growth LoRaSIM Log-distance path loss model Parameters from small-scale experiments Capture effect & collision conditions LoRaWANSim [6] Bor et

, Does Bidirectional Traffic Do More Harm Than Good in LoRaWAN Based LPWA Networks?, Proc. of IEEE Globecom 2017.

15 Simulating growth LoRaSIM Log-distance path loss model Parameters from small-scale experiments Capture effect & collision conditions LoRaWANSim [6] Bor et al., Do LoRa Low-Power Wide-Area Networks Scale?, Proc. of MSWiM [7] Pop et al., Does Bidirectional Traffic Do More Harm Than Good in LoRaWAN Based LPWA Networks?, Proc. of IEEE Globecom LoRaSim extended with LoRaWAN Up- and downlink traffic NS-3 LoRaWAN module [8] Van den Abeele et al., Scalability Analysis of Large-Scale LoRaWAN Networks in ns-3, IEEE Internet of Things Journal, vol. 4, no. 6, Dec All conclude that scalability is an issue! 15

16 Improvements 16

17 Application-layer coding Sender Frame 1 Receiver Sender Data 1 + redundant data Receiver ACKs and retransmissions are costly ACK 1 Frame 2 Frame 2 Data 2 + redundant data Data 3 + redundant data Encoding is more efficient ACK 2 Recover Data 2 Frame 3 ACK 3 [9] Marcelis et al., DaRe: Data Recovery through Application Layer Coding for LoRaWAN, Proc. of ACM/IEEE IoTDI, April

18 Chirp Spread Spectrum (CSS) One chirp = 1 symbol = SF bits One chirp covers entire BW Frequency offset (+ wraparound) determines symbol Amplitude Source: Time (1 up-chirp) Time (1 down-chirp) 18

19 Disentangling collisions Hardware imperfections cause frequency offsets The offset allows to separate the chirps Source: [10]. [10] Eletreby et al., Empowering Low-Power Wide Area Networks in Urban Settings, Proc. of ACM SIGCOMM, Aug

20 Range extension [10] Correlate sensor data Source: Presentation slides accompanying [10], available at choir.pdf. 20

21 LoRa backscatter mm Source: [11] µw (1000x lower than LoRa chipsets) Up to 2.8 km away Multiple backscatter devices on 1 tone [11] Talla et al., LoRa Backscatter: Enabling The Vision of Ubiquitous Connectivity, Proc. of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies, vol. 1, no. 3, Sep

22 (My) Research continues! More pointers will be placed at: 22

When LoRaWAN Frames Collide

When LoRaWAN Frames Collide ABSTRACT Andri Rahmadhani Delft University of Technology Delft, The Netherlands andrewash@gmail.com LoRa, an abbreviation of Long Range, is a Low-Power Wide Area Network (LPWAN)