Long Range Wireless IoT Technologies:

Long Range Wireless IoT Technologies: Low Power Wide Area Network (LPWAN) vs Cellular Anne-Lena Kampen Trondheim 18 th of May 2017

Outline Introduction Long Range Wireless IoT Technologies; characteristics Cellular approaches Proprietary approaches Standards Comparing cellular versus LPWAN Research challenges Conclusion 2

Introduction Internet of Things Internet: Worldwide network Things: Machines, parts of machines, smart meters, sensors.. Worldwide network of interconnected objects IoT is not a single market There are may different usage with different tradeoff in terms of: Delay Range Throughput Reliability 3

IoT is made up of a loose collection of different, purpose-built networks L. Atzori, A. Iera, and G. Morabito, "The internet of things: A survey," Computer networks, vol. 54, no. 15, pp. 2787-2805, 2010. 4

Introduction Long Range Wireless IoT Low Power Wide Area Networks ( LPWAN) is part of the solution for IoT. LPWAN is not a single technology but a collection aimed at different markets Cellular adapts to IoT market with different tradeoff The share of LPWAN connections (all M2M) will grow [1] 58 million in 2016 1 billion by 2021 [1] Global Mobile Data Traffic Forecast Update, 2016 2021 White Paper, Cisco Visual Networking Index, Cisco mars 2017, Available, http://www.cisco.com/c/en/us/solutions/collateral/service-provider/visual-networking-index-vni/mobile-white-paper-c11-520862.html 5

Introduction Long Range Wireless IoT ETSI defines Low Throughput Network (LTN) [1] Long range; 10-12 km (city) 40-60 km (countryside) Low throughput; few bytes per day, week or month Ultra low power on the end points Low cost of operations Low cost of ownership. [1] Low throughput networks (ltn); use cases for low throughput networks, ETSI GS LTN 001 V1.1.1, September 2014. [Online]. Available: http://www.etsi.org/deliver/etsi gs/ltn/001 099/001/01.01. 01 60/gs LTN001v010101p.pdf 6

Long Range Wireless IoT Technologies; Network layer Long range transmission compared to multihop Advantage Multihop have unequal and unpredictable energy consumption Management traffic, forwarding Multihop require dense and expensive deployment of infrastructure Disadvantage Long range have lower data rate 7

Long Range Wireless IoT Technologies; Medium access layer The simple Aloha protocol used in several technologies Low delay However, high Collison probability Carrier sense protocols (CSMA) Reduces collisions However, in LPWAN a high number of nodes may be hidden nodes Request to send/ Clear to send (RTS/CTS) Prevents collisions Less effective for short data packets Added communication overhead Time division multiple access (TDMA) Reduces collisions Increase overhead Advanced protocols requiring tight synchronization is challenging due to cheep end device oscillators Time-frequency resources; figure from[1] [1] A. Laya, L. Alonso, and J. Alonso Zarate, "Is the Random Access Channel of LTE and LTE-A Suitable for M2M Communications? A Survey of Alternatives," IEEE Communications Surveys and Tutorials, vol. 16, no. 1, pp. 4-16, 2014. 8

Duty cycle Active / sleep - duty cycling of the end-devices is used to reduce energy consumption Downlink only after uplink: End-devise stays awake a limited time after transmission Scheduled downlink: A node periodically wake up There are restrictions limiting the duty cycle for some ISM bands 0.1-10 % of the time 9

Frequency Mainly sub-ghz ISM band Some use 2.4GHz Free of charge Lower frequency signals experience less attenuation and multipath fading However, Cross-technology interference Cellular Licensed frequencies 10

Modulation Receivers sensitivity is improved by slower modulation rate (slower data rate) Narrowband: (<25kHz) Share the overall spectrum efficiently Reduced noise However, low data rate Ultra narrow band (UNB) (100Hz) Efficient share of spectrum However, very low data rate Increased duty time Spread spectrum techniques Several users Harder to detect by an eavesdropper More resilient to interference However, require larger BW 11 1

Cellular 3GPP: 3rd Generation Partnership Project (3GPP) [1] The united telecommunications standard development organization Produce Reports and Specifications that define 3GPP technologies: Cellular network technologies [1] http://www.3gpp.org/ 12

Cellular LTE New device category have the following reduced capabilities [1] One receive (Rx), one receiver chain. Reduced peak data rates;1 mbps in downlink and uplink. Optional half-duplex FDD (Frequency Division Duplex) operation LTE modulation [2] : Downlink OFDMA (Orthogonal Frequency Division Multiple Access) High peak-to-average Uplink SC-FDMA (Single carrier) Low peak-to-average [1] R. Ratasuk, A. Prasad, Z. Li, A. Ghosh, and M. A. Uusitalo, "Recent advancements in M2M communications in 4G networks and evolution towards 5G," in Intelligence in Next Generation Networks (ICIN), 2015 18th International Conference on, 2015, pp. 52-57: IEEE. [2] 3GPP online information: http://www.3gpp.org/technologies/keywords-acronyms/98-lte 13

Cellular NB-IoT Narrowband IoT (NB-IoT) (3GPP Rel.13) [1] NB-IoT is designed to be tightly integrated with LTE Three different type of deployment BW: 180 khz Figure from [2] Uplink: (SC- FDMA) (Single-carrier Frequency Division Multiple Access) 170 kbps Downlink: Orthogonal FDMA (OFDMA) in downlink, 250 kbps [2] [1] LTE: Evolved Universal Terrestial Radio Access (E-UTRA); Mediaum Access Control (MAC) protocol specification (3GPP TS 36.321 version 13.2.1 Release 13), available, http://www.etsi.org/deliver/etsi_ts/136300_136399/136321/13.02.00_60/ts_136321v130200p.pdf [2] LTE evolution for IoT connectivity Nokia white paper, Nokia 2017. Available http://resources.alcatel-ucent.com/asset/200178 14

Cellular 5G Wireless First standard is expected in 2020 [1] High-frequency 3 300 GHz Data rate 1 10 Gbps Support IoT (M2M) Figure from [1] To support massive IoT connections: Heterogeneous Networks (HetNets), small cells having low transmission power MAC layer protocols CSMA; adapted for directional antennas [2], TDMA; spatial reuse enables concurrent transmission [1]M. Agiwal, A. Roy, and N. Saxena, "Next generation 5G wireless networks: A comprehensive survey," IEEE Communications Surveys & Tutorials, vol. 18, no. 3, pp. 1617-1655, 2016. [2] M. X. Gong, D. Akhmetov, R. Want, and S. Mao, "Multi-user operation in mmwave wireless networks," in Communications (ICC), 2011 IEEE International Conference on, 2011, pp. 1-6: IEEE. 15

Comparing cellular - summary LTE NB-IoT 5G Link budget 141dB 164dB Output power 23dBm 23dBm BW 20Mhz 180kHz Data rate 1mbps UL & DL 250 kbps UL 170 kbps DL Power saving mode X X X 10Gbps 16

Proprietary - LPWAN LoRa Sub-GHz ISM band[1, 2] Phy layer, proprietary CSS (Chirp Spread Spectrum) The data rate ranges from 300 bps to 37.5 kbps Link budget 154 db [3 ] Figure from [1] LoRaWAN, layer above physical is defined by LoRa TM Alliance LoRaWAN TM specification Unslotted Aloha Topology: star-of-star topology End device does not associate with a certain gateway, only to the backhaul NetworkServer Three different classes of end-devices [1] M. Centenaro, L. Vangelista, A. Zanella, and M. Zorzi, "Long-range communications in unlicensed bands: The rising stars in the IoT and smart city scenarios," IEEE Wireless Communications, vol. 23, no. 5, pp. 60-67, 2016. [2] K. Mikhaylov, J. Petäjäjärvi, and T. Haenninen, "Analysis of capacity and scalability of the LoRa low power wide area network technology," in European Wireless 2016; 22th European Wireless Conference; Proceedings of, 2016, pp. 1-6: VDE. 17 [3] R. S. Sinha, Y. Wei, and S.-H. Hwang, "A survey on LPWA technology: LoRa and NB-IoT," ICT Express, 2017

Proprietary - LPWAN SigFox SIGFOX one of the first LPWAN technologies proposed for IoT, founded in 2009 [1,2] Global connectivity to a single core Link budget 155dB Sub-GHz ISM band carrier Ultra narrow band (UNB) 100Hz Data rate 100 bps! Aloha based access protocol [3] Optimized for uplink transmissions Retransmit default 3 times [1]G. Margelis, R. Piechocki, D. Kaleshi, and P. Thomas, "Low throughput networks for the IoT: Lessons learned from industrial implementations," in Internet of Things (WF-IoT), 2015 IEEE 2nd World Forum on, 2015, pp. 181-186: IEEE. [2]: LPWAN Overview : draft-ietf-lpwan-overview-01, IETF, February 2017, Available, https://datatracker.ietf.org/doc/draft-ietflpwan-overview/01/ [3] A. Laya, C. Kalalas, F. Vazquez-Gallego, L. Alonso, and J. Alonso-Zarate, "Goodbye, aloha!," IEEE access, vol. 4, pp. 2029-2044, 2016. 18

Proprietary - LPWAN Ingenu (former OnRamp Wireless) Star network topology [1] Link budget 168dB 78kbps UL, 19.5 kbps DL Uplink: Patented Random Phase Multiple Access Direct Sequence Spread Spectrum (RPMADSSS) or just RPMA Downlink: CDMA [Low throughput Network in the IoT Lessons learned] 2.4 GHz ISM band More relaxed regulations on the spectrum use across regions Deployed in USA- 22 cities. CDMA RPMA [1] G. Margelis, R. Piechocki, D. Kaleshi, and P. Thomas, "Low throughput networks for the IoT: Lessons learned from industrial implementations," in Internet of Things (WF-IoT), 2015 IEEE 2nd World Forum on, 2015, pp. 181-186: IEEE. 19

Standards IEEE 802.15.4k Topology : Star Sub-GHz and 2.4GHz ISM band Modulation DSSS and FSK Link budget up to 120dB Coverage 5-20 km Data rate 300 bps 1.2 kb/s Figure from[1] MAC: CSMA/CA or Aloha with or without PCA (Priority channel access) [1] PCA: Introduce PCA slot in which only high priority message can be transmitted [1] B. G. Gebremedhin, J. Haapola, and J. Iinatti, "Performance Evaluation of IEEE 802.15. 4k Priority Channel Access with DSSS PHY," in European Wireless 2015; 21th European Wireless Conference; Proceedings of, 2015, pp. 1-6: VDE. 20

Standards 802.11ah Single hop Range 0.1-1Km Supports 800 nodes [1] Frequency band Sub-1GHz [2] Data rate: 0.15 7.8 Mb/s Modulation: OFDM MAC: Divide the stations into Traffic Indication Map, TIM groups Different scheduling to different group Contend for channel access only among group members- CSMA [1] A. Laya, C. Kalalas, F. Vazquez-Gallego, L. Alonso, and J. Alonso-Zarate, "Goodbye, aloha!," IEEE access, vol. 4, pp. 2029-2044, 2016. [2] T. Adame, A. Bel, B. Bellalta, J. Barcelo, and M. Oliver, "IEEE 802.11 AH: the WiFi approach for M2M communications," IEEE Wireless Communications, vol. 21, no. 6, pp. 144-152, 2014. 21

Comparing LPWAN - summary LoRaWAN SigFox Ingenu IEEE 802.15.4 IEEE 802.11 ah Link budget 154dB 155dB 168dB 120dB MAC Unslotted Aloha Unslotted Aloha Slotted Aloha-like CSMA, Aloha /PCA Data rate 300bps-37.5kbps 100 bps 78kB(UL) 19.Kbps (DL) Coverage range km Rural: 10 15 Urban: 3 5 Rural: 30 50 Urban: 3 10 300bps- 1.2 kbps CSMA 0.15-7.8mbps Urban: 15 5-20 km 0.1-1Km Aloha approach in DSSS channels is validated in [1]: IEEE802.15k prototype radio, urban environments and 5 end-devices. The preamble of each packets is properly detected and distinguishable. Calculations [2] LoRaWAN, suburban: Can serve up to 7 million units. However, less than 10% of the enddevices can reside at a distance over 5km. [1] X. Xiong, K. Zheng, R. Xu, W. Xiang, and P. Chatzimisios, "Low power wide area machine-to-machine networks: Key techniques and prototype," IEEE Communications Magazine, vol. 53, no. 9, pp. 64-71, 2015. [2] K. Mikhaylov, J. Petäjäjärvi, and T. Haenninen, "Analysis of capacity and scalability of the LoRa low power wide area network technology," in European Wireless 2016; 22th European Wireless Conference; Proceedings of, 2016, pp. 1-6: VDE. 22

Comparing Technologies LPWAN LoRaWAN SigFox Ingenu IEEE 802.15.4 IEEE 802.11 ah Link budget 154dB 155dB 168dB 120dB Data rate 300bps-37.5kbps 100 bps 78kB(UL) 19.Kbps (DL) Cellular LTE NB-IoT 5G Link budget 141dB 164dB Data rate 1mbps UL & DL 250 kbps UL 170 kbps DL 10Gbps 300bps- 1.2 kbps 0.15-7.8mbps NB-IoT SigFox BW 180kHz 100Hz Link budget 164dB 155dB Data rate 250 kbps UL, 170 kbps DL 100 bps 23

Comparing technologies Cellular Massive infrastructure (Worldwide?) - Continued investment Global standard infrastructure Licensed spectrum - Cost Time and frequency resources are to be shared between M2M and H2H Massive amount of M2M devices increase signaling and control traffic Different communication characteristics QoS can be guaranteed Secure communication (SIM card) The cost and complexity is high Concurrent transmit messages form a large number of M2M devices can impact the operation of the whole mobile network LPWAN Some infrastructure Several LPWAN technologies, no interoperability Unlicensed spectrum, free of charge Every country has different rules about using the sub-ghz spectrum. ISM employs different SubGHz frequency band: Europe (868 MHz), U.S. (915 MHz) Cross-technology interference QoS requirements difficult to guarantee Some solutions have poor security (ex. SigFox) Stripped complexity to reduce cost. Improving LPWAN scalability with increased base-station density Interference 24

Standardization ETSI [1]: Standardize low data rate LPWAN Low Throughput Networks (LTN); Use Cases for Low Throughput Networks Low Throughput Networks (LTN); Functional Architecture Low Throughput Networks (LTN); Protocols and Interfaces IETF [2]: The range of several kilometers and a long battery lifetime, has a price The application is often wired to the layer 2 frame format However, the systems should be able to interoperate The IETF contribute by providing IPv6 connectivity Propose technologies to secure the operations and Manage the devices and their gateways [1] Low throughput networks (ltn); use cases for low throughput networks, ; Low throughput networks (ltn); functional architecture, ; Low throughput networks (ltn);protocols and interfaces, ETSI GS LTN 001 V1.1.1, September 2014. [Online]. Available: http://www.etsi.org/deliver/etsi gs/ltn/001 099/001/01.01. 01 60/gs LTN001v010101p.pdf [2] LPWAN Work Group about, available, https://datatracker.ietf.org/wg/lpwan/about/ 25

Research challenges - I Scalability LPWAN specific Challenge: Cross-technology interference Authority can propose rules for spectrum sharing Improve channel access techniques Cellular specific Challenge: Resource sharing H2H vs M2M Challenge for M2M traffic: Low ratio between payload and control information Improve channel access techniques 26

Research challenges - II Scalability [1,2] Use of multiple base-stations to improve availability Challenge: Interference, management and low spectrum utilization Effective spectrum sharing; cognitive radio Transmission schedule MAC layer protocols Challenge: congestion, collisions, BW-utilization Appropriate backoff parameter settings Slotted solutions require some signaling overhead Cellular networks are designed by network operators [1] U. Raza, P. Kulkarni, and M. Sooriyabandara, "Low Power Wide Area Networks: An Overview," IEEE Communications Surveys & Tutorials, vol. PP, no. 99, pp. 1-1, 2017. [2] F. Ghavimi and H.-H. Chen, "M2M communications in 3GPP LTE/LTE-A networks: architectures, service requirements, challenges, and applications," IEEE Communications Surveys & Tutorials, vol. 17, no. 2, pp. 525-549, 2015. 27

Research challenges - III Scalability suggested solutions MAC layer: Contention-based access for LTE: Example of suggested improvement [1]: Include data into the contention process Modify the Access Class Barring mechanism Split the available preambles into H2H and M2M Distributed Queue (DQ) based on two ques [2]: Colliding data enters Contention Resolution Queue Success data enters Data Transmission Queue Implement DQ in the RA procedure of the LTE standard. Simulation: Include RA in LTE Blocking probability becomes unaffected by the increase in simultaneous arrivals. [1] A. Laya, L. Alonso, and J. Alonso-Zarate, "Is the Random Access Channel of LTE and LTE-A Suitable for M2M Communications? A Survey of Alternatives," IEEE Communications Surveys and Tutorials, vol. 16, no. 1, pp. 4-16, 2014. [2] A. Laya, C. Kalalas, F. Vazquez-Gallego, L. Alonso, and J. Alonso-Zarate, "Goodbye, aloha!," IEEE access, vol. 4, pp. 2029-2044, 2016. 28

Research challenges IV Scalability suggested solution: Group based operations of M2M communication: group leader collects and forwards the information to the LTE/ LTE-A station[1] 5G: IoT gateway[2] : Downlink connect the IoT devices using ex. ZigBee Uplink connect cellular network. Traffic classification Buffered in MAC buffers until transmission is triggered Compression A testbed setup of Classification reduced the number of uplink transmission form 120 to 60 Further, using compression the number is reduced to 25. [1] F. Ghavimi and H.-H. Chen, "M2M communications in 3GPP LTE/LTE-A networks: architectures, service requirements, challenges, and applications," IEEE Communications Surveys & Tutorials, vol. 17, no. 2, pp. 525-549, 2015. [2] N. Saxena, A. Roy, B. J. Sahu, and H. Kim, "Efficient IoT Gateway over 5G Wireless: A New Design with Prototype and Implementation Results," IEEE Communications Magazine, vol. 55, no. 2, pp. 97-105, 2017. 29

Research challenges - V Interoperability [1] Several LPWAN technologies Challenge: No interoperability Challenge: Lack of universal infrastructure Challenge: Cost and revenue sharing / managing Standards needed to glue them together IP based gateways [1] U. Raza, P. Kulkarni, and M. Sooriyabandara, "Low Power Wide Area Networks: An Overview," IEEE Communications Surveys & Tutorials, vol. PP, no. 99, pp. 1-1, 2017. 30

Research challenges - VI Location challenge [1] Various applications require accurate localization information objects, patients, alarms.. Require accurate time synchronization and high base-station density. Locate the base station that a node is connected to Cellular provides location within base station area Reliability /robustness challenges Low base-station density, base-station becomes a single point of failure High base-station density: interference Cross-technology interference Cellular managed by network operators; hence more robust [1] U. Raza, P. Kulkarni, and M. Sooriyabandara, "Low Power Wide Area Networks: An Overview," IEEE Communications Surveys & Tutorials, vol. PP, no. 99, pp. 1-1, 2017. 31

Research challenges -VII High data rate modulation techniques [1] Modulation methods offer very low data rates. Higher data rates (more complex modulation schemes) increases the area of utilization Challenge: increase hardware cost, reduces transmission rage Link optimization and adaptability Methods that adaptively monitor link quality to optimize performance Challenge: downlink information generally needed [1] U. Raza, P. Kulkarni, and M. Sooriyabandara, "Low Power Wide Area Networks: An Overview," IEEE Communications Surveys & Tutorials, vol. PP, no. 99, pp. 1-1, 2017. 32

Research challenges - VIII Security [1,2] Challenge: Low energy nodes, limited data exchange Cellular: Subscriber Identity Modules (SIM) for identification and authentication. LRWA: Some solutions have poor security (SigFox do not encrypt payload (end-device < > base station)) Mobility and roaming [1,2] Challenge: Revenue, billing, varying spectrum regulations Provide roaming without compromising end-devices lifetime LPWAN: Low downlink communication rate, exploit uplink data Cellular networks have some roaming [1] U. Raza, P. Kulkarni, and M. Sooriyabandara, "Low Power Wide Area Networks: An Overview," IEEE Communications Surveys & Tutorials, vol. PP, no. 99, pp. 1-1, 2017. [2] F. Ghavimi and H.-H. Chen, "M2M communications in 3GPP LTE/LTE-A networks: architectures, service requirements, challenges, and 33 applications," IEEE Communications Surveys & Tutorials, vol. 17, no. 2, pp. 525-549, 2015.

Research challenges - IX Quality of Service [1,2] Cellular network: QoS guarantee is easier in the licensed spectrum LPWAN: QoS challenging due to unlicensed, spectrum, duty-cycle requirement etc. [1] U. Raza, P. Kulkarni, and M. Sooriyabandara, "Low Power Wide Area Networks: An Overview," IEEE Communications Surveys & Tutorials, vol. PP, no. 99, pp. 1-1, 2017. [2] F. Ghavimi and H.-H. Chen, "M2M communications in 3GPP LTE/LTE-A networks: architectures, service requirements, challenges, and 34 applications," IEEE Communications Surveys & Tutorials, vol. 17, no. 2, pp. 525-549, 2015.

Conclusion There are various technologies addressing the huge IoT marked The cellular and the LPWAN technologies offers different capabilities This may cause a differentiation between markets Cellular offer better bit rate, QoS and have higher geographical coverage LPWAN offer low initial cost and operation cost, and long lifetime. In addition flexible network design. In order to prevent vendor lock-in, standards are required 35

Thank you for listening! 36