Submission Title: IEEE Standards for Low Power Wide Area Networks July 2016 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: IEEE Standards for Low Power Wide Area Networks Date Submitted: July 2016 Source: Joerg Robert, Friedrich-Alexander University (FAU) Am Wolfsmantel 33, 91058 Erlangen, Germany Abstract: Suitability of IEEE Standards for LPWAN Purpose: Discussion in IEEE 802.15 SC WNG Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. Joerg Robert

IEEE Standards for Low Power Wide Area Networks July 2016 IEEE Standards for Low Power Wide Area Networks Joerg Robert July, 2016 Joerg Robert

Concept of Low Power Wide Area Networks (LPWAN) July 2016 Concept of Low Power Wide Area Networks (LPWAN) e.g. 100m e.g. 40km e.g. 10dBm Small and cost-efficient sensors nodes communicate using ultra-low power over ultra-long distances The base-stations antennas are typically mounted at highly exposed sites (e.g. on top of TV broadcast transmitter masts) A typical base-station serves up to one million sensor nodes Typical application scenarios: Water/gas metering, environmental monitoring, ... [1] Joerg Robert

Advantages of LPWAN / Motivation July 2016 Advantages of LPWAN / Motivation Possibility to setup large and cost-efficient networks, as only few base-stations are required Possibility for ultra-low-cost and ultra-small devices that can operate for many years using tiny AA batteries BUT: How well is this network type covered by IEEE standards? Which potential standards do exist? Joerg Robert

July 2016 Challenges of LPWAN Ultra-low power in addition to long distances leads to very weak reception levels (typical assumption < -140dBm) Very low bit rates (1 < kbit/s) Interference from other services as license-exempt bands are commonly used (e.g. 434MHz, 868/915MHz, 2.4GHz) Further increased interference at base-station due to highly exposed antennas Concepts as CSMA (Carrier Sense Multiple Access) do not work because of the hidden node problem Use of spread spectrum (e.g. DSSS) or frequency hopping .... and many additional challenges Joerg Robert

Measured Spectrum in 868MHz Band July 2016 Measured Spectrum in 868MHz Band Joerg Robert

Potential Standards for LPWANs July 2016 Potential Standards for LPWANs Focusing on license-exempt bands: IEEE 802.15.4k SIGFOX LoRaWAN ETSI LTN, Weightless, IEEE 802.11ah ... Focusing on licensed bands: 3GPP standards, e.g. NB-IoT (Narrow Band IoT) Joerg Robert

Performance Evaluation in AWGN July 2016 Performance Evaluation in AWGN Payload bit rate as function of the reception level can be theoretically calculated using Shannon‘s findings for ideal systems Assumptions: Eb/N0=-1.59dB Noise figure 0dB Noise power spectral density -174dBm/Hz Joerg Robert

Max. Payload Bit Rate vs. Rx Power July 2016 Max. Payload Bit Rate vs. Rx Power Example: -140dBm3.6kbit/s Joerg Robert

July 2016 IEEE 802.15.4k DSSS-PHY ( I / II ) Amendment 5: Physical Layer Specification for Low Energy, Critical Infrastructure Monitoring Networks (LECIM) DSSS Phy based on Gold (and optional OVSF code) with modulation rate 200ksym/s ... 1000ksym/s Spreading factor up to 32768  R=3bit/s (BPSK)  Min. telegram length of 42s!  Max. spreading factor limited to 256 in the US (FCC regulation, max. 0.4s signal duration, [4, Q.2.1]) Interference reduction capabilities (linear receiver) of 45dB (spreading of 32768) and 25dB (spreading of 256) 2.5ppm radio frequency tolerance  requires precise oscillators Joerg Robert

IEEE 802.15.4k DSSS PHY ( II / II ) FCC Max. Robust July 2016 IEEE 802.15.4k DSSS PHY ( II / II ) FCC Max. Robust Assumptions concerning noise figure and implementation loss are unclear! Joerg Robert

IEEE 802.15.4k FSK-PHY Second Phy offered by 802.15.4k July 2016 IEEE 802.15.4k FSK-PHY Second Phy offered by 802.15.4k (Position based) (G)FSK modulation down to very low rates 0.5kbit/s Document states minimum required receiver sensitivity of -97dBm, independently of any modulation and coding  Would correspond to 37dB loss wrt. theory No real robustness wrt. interferers, as no frequency hopping or spreading are used Potential issue with required frequency accuracy Joerg Robert

July 2016 SIGFOXTM ( I / II ) SIGFOX is a fully proprietary system offered by the company SIGFOX  detailed information about the system is not available The modulation format is BPSK using a data rate of 100bit/s where each message contains 12 bytes payload [3]  Telegram time of approx. 6s (each message is transmitted three time  effective rate of 33bit/s) The original SIGFOX standard is not FCC compliant [3]  Modified version for US market with less link budget Robustness against interference is reached by means of three transmissions of the same data on different channels Joerg Robert

July 2016 SIGFOXTM ( II / II ) Assumed receiver sensitivity of -142dBm [3] with 33bit/s effective bit rate (does potentially not include receiver noise figure) Joerg Robert

July 2016 LoRaWANTM ( I / II ) Specification of the LoRa Alliance (mainly driven by Semtech) Modulation uses spread spectrum with data rate ranging from 0.3 kbps to 50 kbps Interference reduction capabilities due to spread spectrum modulation Performance figures available due to existing chip implementations [5], e.g. 18 bit/s at -148dBm Joerg Robert

July 2016 LoRaWANTM ( II / II ) Assumed receiver sensitivity of -148dBm with 18bit/s effective bit rate (represents available receiver design SX 1276 [5] including all implementation losses) Joerg Robert

Other Standards for License-Exempt Bands July 2016 Other Standards for License-Exempt Bands ETSI is working on “ETSI LTN” standard for LPWANs [2] Contributions from SIGFOX, Semtech, ... Weightless is an additional standard for sub-GHz LPWAN [6] Based on DBPSK with ultra-low bandwidth (similar to SIGFOX) IEEE 802.11ah Slowest mode offers 150kbit/s  perfect system would require PRx=-123dBm  no real long-range system Joerg Robert

3GPP NB-IoT Narrow Band IoT is part of 3GPP Release 13 [7] July 2016 3GPP NB-IoT Narrow Band IoT is part of 3GPP Release 13 [7] System can operate stand-alone, in LTE guard band or within normal LTE carrier NB-IoT was created under strong pressure from the mobile network operators Further enhancements will be part of 3GPP Release 14 Joerg Robert

Summary LPWANs are interesting networks for many applications July 2016 Summary LPWANs are interesting networks for many applications A variety of proprietary and non-IEEE standards are appearing The full suitability of existing IEEE standards for LPWANs is not clear Existing standards may offer significant room for improvements The 3GPP community is highly focusing on the development of LPWAN standards Joerg Robert

July 2016 What should IEEE do? Should IEEE leave the field to 3GPP and proprietary systems? OR Investigate the suitability of existing IEEE standards for LPWANs? Possible way forward: Setup Interest Group to evaluate existing IEEE standards Create usage scenarios for license-exempt bands Create suitable channel and interference models Investigate performance of existing standards Joerg Robert

July 2016 Questions? Joerg Robert

July 2016 References [1] X. Xiong, K. Zheng, R. Xu, W. Xiang and P. Chatzimisios, "Low power wide area machine-to-machine networks: key techniques and prototype," in IEEE Communications Magazine, vol. 53, no. 9, pp. 64-71, September 2015. [2] http://www.etsi.org/news-events/news/827-2014-09-news-etsi-new-specification- for-internet-of-things-and-machine-to-machine-low-throughput-networks [3] http://theinternetofthings.report/Resources/Whitepapers/4cbc5e5e-6ef8-4455- b8cd-f6e3888624cb_RPMA%20Technology.pdf [4] IEEE 802.15.4k Amendement [5] http://www.semtech.com/images/datasheet/sx1276_77_78_79.pdf [6] www.weightless.org [7] http://www.3gpp.org/news-events/3gpp-news/1733-niot Joerg Robert