LoRaWAN Radio Interface Analysis for North American Frequency Band Operation Ahmed Alsohaily, Elvino Sousa University of Toronto Toronto, Canada Email:{ahmed.alsohaily, es.sousa}@utoronto.ca Adam J. Tenenbaum, Ivo Maljevic TELUS Toronto, Canada Email:{adam.tenenbaum, ivo.maljevic}@telus.com Abstract—Numerous candidate systems have emerged to address the connectivity requirements of Low Power Wireless Access (LPWA) Internet of Things (IoT) applications for massive Machine Type Communication (MTC). This paper analyzes the radio interface design of LoRaWAN systems operating in the North American 915 MHz licence-exempt frequency band. After providing a detailed overview of LoRaWAN system and connectivity structuring, the performance of LoRaWAN radio interface under the default North American mode of operation is thoroughly analyzed. Specifically, coverage, capacity and End Device (ED) throughput rates are determined for defined LoRaWAN Data Rate (DR) classes. Analysis of the LoRaWAN radio interface reveals a requirement of non-uniform ED distribution to attain maximal coverage and capacity, with the DR class achieving maximal coverage providing 1% of the peak capacity and the DRs providing 76% of the maximal capacity confined within 26% of the peak coverage area. Keywords—IoT; LoRa; LoRaWAN; LPWA; RAT; wireless IoT. I. INTRODUCTION The emergence of wireless Internet of Things (IoT) applications has ignited a new gold rush era for wireless system design and structuring as existing wireless systems fall short in scaling to wireless IoT connectivity requirements [1]. In particular, numerous newly introduced wireless systems, standards and technologies such as Sigfox, LoRa, Ingenu, EC-GSM, LTE MTC and NB-IoT aim to cater to the requirements of Low Power Wireless Access (LPWA) IoT connectivity scenarios for massive Machine Type Communication (mMTC) [1], [12], [13]. As was the case for early cellular communication systems, the introduction of new radio interfaces is at the centre of LPWA system development. For example, Sigfox, LoRaWAN and Ingenu systems adopt various modulation and user multiple access schemes for exploiting Industrial, Scientific and Medical (ISM) licence-exempt frequency bands to reduce initial system deployment costs. On the other hand, EC-GSM, LTE MTC and NB-IoT systems rely on licensed frequency bands to attain reliable system operation [1]. This paper aims to elevate the scarce efforts towards analyzing the performance of LoRaWAN systems [3] – [7] by providing a detailed analysis of the radio interface design for LoRaWAN systems operating in the North American 915 MHz ISM licence-exempt frequency band and is organized as follows. Section II provides a thorough overview of LoRaWAN system structuring, frequency band plan, End Device (ED) classes, channel access and data transmission. Section III evaluates the radio interface of LoRaWAN systems for the defined default mode of operation in North America and Section IV conclusions the paper. II. LORAWAN SYSTEMS A. Architecture and Radio Access LoRaWAN systems deploy Access Gateways to connect LoRaWAN End Devices (EDs) to a remote, centralized network server, as shown in Fig. 1, and utilize LoRa radio access to facilitate wireless data transmission between access gateways and LoRaWAN EDs [2], [8] – [11]. LoRa radio access, based on a proprietary Chirp Spread Spectrum (CSS) modulation, spreads data signals using a wideband chirp signal with continuously varying frequency [8] – [11]. For any Spreading Factor SF and transmission bandwidth W, the LoRa symbol period, TS, and symbol rate, RS, are equal to [8] – [11]: Fig. 1: LoRaWAN system architecture. 978-1-5386-3531-5/17/$31.00 ©2017 IEEE This work is supported in part by TELUS and in part by Mitacs. LoRaWAN End Device LoRaWAN End Device LoRaWAN End Device … LoRaWAN Access Gateway Network Server Backhaul LoRaWAN End Device LoRa Air Interface Authorized licensed use limited to: The University of Toronto. Downloaded on April 29,2022 at 16:59:48 UTC from IEEE Xplore. Restrictions apply.