Pioneers in NB-IoT testing What do you really need to know? The most important facts and solutions. eguide Version 01.01
Contents IoT and NB-IoT market and use cases IoT technologies and terminology NB-IoT network testing solutions from a single source NB-IoT testing using network scanners NB-IoT testing using cellular IoT devices NB-IoT network optimization and troubleshooting A real-world experience in connecting a cellular NB-IoT device to a network NB-IoT base station deployment verification Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 2
Is IoT really a significant market for cellular technologies? A wide variety of analysts are forecasting the IoT market in terms of volume (in billions or trillions of dollars) and in terms of connected IoT devices. The figures differ significantly, but there is broad agreement in the industry that the market will grow substantially. The Ericsson Mobility Report is on the conservative side of the forecasts. Forecast of connected IoT devices 2017 2023 7 20 billion billion It is true that the vast majority of connected IoT devices will use short-range technologies. However, 500 million connected cellular wide area network devices already deployed in 2017 with forecasted growth to 1.8 billion devices in 2023 sends a strong message: the cellular IoT market is already there and will undoubtedly grow significantly. Cellular wide area network technologies, in particular for security and mission critical use cases and applications, require very high network reliability and availability where proper device testing and also network testing is a must to always ensure the essential quality of service. Short-range Cellular WAN Unlicensed WAN 2017 2023 CAGR 6.4 Bn 0.5 Bn 0.1 Bn 17.4 Bn 1.8 Bn 0.6 Bn +18 % +24 % +35 % Presently, the dominant technology in the wide area network segment is GSM/GPRS. However, by 2023, IoT cellular connectivity will mainly be provided by LTE and 5G. Source: Ericsson Mobility Report, Nov. 2017 Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 3
Examples of NB-IoT use cases Use cases for the Internet of Things (IoT) are virtually unlimited and nobody can presume to know the most successful ones in the future. Here are a few examples and the main benefits. Smart waste management Main benefits: Report the bin s fullness to ensure timely removal Cost savings (waste removal only when needed, improved routing) Monitor activities of cleaning services Smart metering Main benefits: Cost savings (OPEX) End-user friendly Improved supply efficiency through accurate usage records Maintenance (fault detection alerts) Smart parking Main benefits: Improve accessibility of parking space Less (search) traffic congestion (fuel, emission, time saving) Optimize existing infrastructure Cost savings (easy payment) 4 Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 4
A plethora of radio technologies for the wireless Internet of Things IoT will strongly continue with 5G (also standardized by 3GPP) The cellular IoT technologies (NB-IoT and LTE-M) are just some of the wide area network IoT technologies among many other wide area, neighbor area, local area and body area network technologies, but they have strong advantages in terms of ecosystem (technology components for devices and in particular base stations) compared to proprietary technologies that rely on a single or a few companies. However, the assumption is that we will see different technologies employed for different IoT use cases and applications that will make use of licensed spectrum (e.g. for cellular 3GPP technologies) and unlicensed, shared spectrum. Again to emphasize: use cases for the Internet of Things (IoT) are virtually unlimited and nobody can presume to know the most successful ones or what will be used commercially in future. Rohde & Schwarz is focusing on cellular wide area network technologies like NB-IoT and LTE-M because here network measurements in terms of RF coverage and sustainable IoT service performance are valuable and highly recommended to ensure a certain guaranteed QoS. Technologies versus deployment areas Cellular IoT we are just at the beginning of an exciting journey LoRaWAN Sigfox Weightless Ingenu Telensa WAVIoT ZigBee/Thread WI-SUN(HAN) Z-Wave enocean Endiio 802.11 ah 802.11 af Bluetooth LE ANT/ANT+ body NFC local area 802.11 a/b/g/n/ac/ax Bluetooth 5 ULE whart ISA100 IQRF ZigBee (HAN) WI-SUN (FAN) Wireless M-Bus Dash7 802.16s GPRS/EC-GSM LTE-M NB-IoT 5G (urllc, mmtc) Rel. 13 Rel. 14 Rel. 15 Rel. 16 Rel. 17 NB-IoT Cat-M1, edrx, CE 1.4 MHz/half-duplex NB-IoT Cat-NB1, edrx, CE 200 khz FeMTC Cat-M2 1.4/5 MHz enb-iot Cat-NB2 200 khz V2x LTE-sidelink efemtc 1.4/5 MHz FeNB-IoT (TDD support) 200 khz ev2x 5G mmtc 5G NR-IoT 5G urllc neighbor area MulteFire 1.0 MulteFire 1.1 2015 2016 2017 2018 2019 2020 wide area networks Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 5
Many ways to say the same thing NB-IoT: narrowband Internet of Things NB-IoT = NB-LTE Cat-NB1/Cat-NB2: UE categories for NB-IoT emtc: enhanced machine type communications emtc = LTE-M = LTE-MTC Cat-M1/Cat-M2: UE categories for LTE-M Main features to limit power consumption PSM: power saving mode edrx: extended discontinuous reception (both allow a sleep mode for NB-IoT devices) Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 6
NB-IoT technology-to-go NB-IoT offers a very easy deployment scenario for operators. With just a software upgrade, NB-IoT functionality can be added to LTE base stations, but the broadcast channel, synchronization signals and reference signals have to be tailored to the NB-IoT carrier bandwidth (180 khz = 1 LTE PRB). For NB-IoT, the 3GPP standard requires more than 20 db higher maximum coupling loss (164 db) than normal LTE (142.7 db) which means more than 20 db better coverage than LTE. Suitable features to ensure this better coverage Reduced occupied channel bandwidth in UL With single tones, the energy can be concentrated to only 2 % of the LTE PRB bandwidth of 180 khz. In-band operation Nb-IoT Nb-IoT In-band operation: One or more LTE PRBs will be replaced by NB-IoT carriers. Reduced occupied channel bandwidth in UL Uplink multitone and downlink resource units (LTE) Single tones (control) 180 khz Multitones LTE carrier Single tones 0 ms 5 ms 10 ms 15 ms 30 ms Guard-band operation Nb-IoT Guard-band operation: NB-IoT carriers can be placed in the slopes of an LTE carrier. Power boosting in DL NB-IoT carrier transmits with e.g. 6 db more power than the LTE PRBs (in-band operation mode). Power boosting in DL LTE carrier Power Standalone operation Nb-IoT e.g. GSM carriers Standalone operation: NB-IoT carriers can replace GSM carriers (200 khz bandwidth). NB-IoT Frequency Repetition of messages Two times the repetitions = 3 db better coverage! High number of repetitions increases network coverage significantly, but also the latency. However, latency is often not critical for NB-IoT use cases. Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 7
All NB-IoT network testing solutions from a single source Rohde & Schwarz mobile network testing offers data collection using network scanners for NB-IoT measurements as well as using cellular NB-IoT devices connected to the R&S ROMES4 analysis and network optimization software that is already known on the market for optimizing networks of all kind of technologies, including recent technologies like LTE. The complete Rohde & Schwarz network scanner family is NB-IoT capable via simple software upgrade. A variety of NB-IoT chipsets and module vendors are also supported. Both measurement solutions focus on different test scopes and complement each other. The scanner measurements provide accurate and fast NB-IoT network DL coverage due to the scanners RF accuracy and information about the coexistence of NB-IoT with e.g. LTE or other technologies. Measurements using NB-IoT and LTE- M devices connected to R&S ROMES4 provide insights into the service performance in particular application layer KPIs, network performance metrics and UL information. In the use case section, we have seen that IoT applications often have to work under extremely demanding receive conditions (e.g. smart meters in basements) and that IoT networks must be optimized for highest availability. Consequently, operators planning and deploying new NB-IoT networks inevitably face the coverage challenge. Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 8
The most accurate and reliable means of identifying network coverage is a network scanner. The radio receiver is a passive device that captures the measurement data directly from the RF air interface. Instead of limiting measurements to one particular operator s cell via a serving cell selection procedure, the passive scanner-based approach enables the capture of data from all operators and all available cells within the receiver sensitivity of the scanner. Significant parameters include power levels (e.g. NRSRP) and signal-to-noise ratios of the different signals in the NB-IoT radio frame. Those parameters allow conclusions to be drawn about the RF conditions at a certain location, which provide the basis for network access through NB-IoT devices. NB-IoT network scanners for accuracy and true coverage information Portable NB-IoT network measurement solution that consists of an R&S TSMA scanner, including network PC, R&S ROMES4 software running on this network PC, RF and GPS antenna, battery and tablet to control the measurements. Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 9
What can be tested by connecting a cellular NB-IoT device to R&S ROMES4? Once the NB-IoT device is connected to a network, the following service performance measurements can be done: Application layer KPIs such as success rate, setup time, transfer time, user data rate and latency Network performance metrics such as spectral efficiency, latency, energy efficiency, resource utilization and coverage (DL and UL) The R&S ROMES4 software tool also analyzes data from connected NB-IoT devices. It provides deep insight into the communications between the NB-IoT network and the device with the NPA functionality (problem spot analysis for scanner and UE) since the above-mentioned measurements can only be done in case of an established connection between the NB-IoT network and the NB-IoT device. A higher CE level means a higher number of message repetitions for better coverage and certainly much higher energy consumption. All these parameters decoded by the NB-IoT UE are available as signals and can be configured as graphs in R&S ROMES4. NB-IoT transmission details: info per TTI from the PRACH, PDSCH, NPUSCH and NPDCCH DCI. Service performance measured with NB-IoT devices connected to R&S ROMES4. 10 Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 10
Example: RACH coverage enhancement (CE) levels Cat-NB UE selects a coverage enhancement (CE) level for the RACH procedure based on comparing current NRSRP with RSRP thresholds signaled in SIB2-NB. We decoded in a live network e.g. RSRP 1 threshold (CE 1) of 31: < 109 dbm (calculation is 140 dbm + 31 db) RSRP 2 threshold (CE 2) of 21: < 119 dbm In the live network, this parameter was set to 4, i.e. after 4 transmitted preambles without a received response message, the NB-IoT UE will step up the CE level. In this example, 9 transmissions were sufficient to set the UE from CE level 0 to CE level 2, although the receive signal level (NRSRP) is more than 30 db better than the 119 dbm RSRP 2 threshold. The CE level also depends on other enb NPRACH parameters such as The maximum number of preamble transmission attempts per enhanced coverage level supported in the serving cell. 2D chart configured with NRSRP, NRSRQ, CE level, NB efficiency (in µws/bit). Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 11
NB-IoT network optimization and troubleshooting Deepest insights can be achieved by collecting data with NB-IoT devices, NB-IoT and LTE scanners in parallel. This particularly helps to identify and solve potential interference issues (troubleshooting) and optimize the NB-IoT network. Since introducing the NB-IoT network measurement capability with scanners and NB-IoT devices supported by our leading engineering tool R&S ROMES4, a myriad of kilometers of drive tests have been executed. We have received valuable feedback from NB-IoT field engineers and found interesting use cases for comprehensive testing with NB-IoT devices and scanners together. If just the information from the NB-IoT device is visualized in our R&S ROMES4 software platform, we only know that the device cannot access the network even though the coverage should be definitely sufficient. If we add the NB-IoT and LTE scanner measurements that have been collected in parallel to the NB-IoT device, we clearly see the root cause of the problem. The NB-IoT scanner confirms the RF data (NRSRP and NRS CINR) of the NB-IoT device for the cell with NPCI 200 (see below). The NB-IoT scanner also shows 10 db CINR. The LTE scanner provides the answer: The cell with PCI 200 is only the fourth best LTE cell in this area (in this situation, it is the worst LTE cell). There are three LTE cells in this area that can be detected with up to 20 db better received power. Exactly these three cells provide a strong interference to LTE cell 200 and certainly also to the NB-IoT carrier that is part of cell 200. This example shows an aborted random access procedure (11 request messages with max. TX power at the end) even though the NRSRP reports very good coverage with 74 dbm (see picture below). The SINR with 7 db already indicates that there is an issue.. Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 12
Our NB-IoT device stated a good coverage level but could not register to the network. Using the NB-IoT scanner in combination with an LTE scanner explained the situation immediately. We always use the scanners in our daily optimization and engineering work. Head of Radio Network Optimization, Tier-one MNO Europe. Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 13
A real-world experience in connecting a cellular NB-IoT device to a network A large number of NB-IoT modules and chipsets with different RF characteristics are already available on the market (and many more will follow). Consequently, our test solution supports a variety of different vendors NB-IoT/LTE-M chipsets and modules. In order to attach to an NB-IoT network, the Cat-NB1 UE must support the network s frequencies a somewhat tricky endeavor since the International Telecommunication Union (ITU) officially divided the world into three radio regulatory regions in which each region has its own set of band allocations. However, the 3GPP has already specified many frequency bands for NB-IoT, mostly below 1 GHz. NB-IoT technology is optimized for small data transfers and minimal load over the radio interface. 3GPP standardized both IP and non-ip data delivery mechanisms, using either control plane or user plane signaling messages. During the attach procedure, the used connection type is controlled by the Cat-NB1 UE. The access point name (APN) is the name of a setting belonging to the subscriber profile that is used to manage the characteristics of the connection between an operator s network and an external network. For example, for IP and non-ip connections, different APNs are used. Consequently, in this early phase of deployments, operators offer NB-IoT packages with a specific predefined NB-IoT subscriber profile that contains default APNs and data transport types that are implemented in dedicated SIM cards. This enables setting up the preferred connection between the UE and the NB-IoT operator s network. Concerning the IP data, our field studies showed that the default APN normally connects to the public Internet, which is what we are used to when testing networks with commercially available smartphones. Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 14
NB-IoT base station deployment verification Measure NB-IoT signal quality with the R&S FSH handheld spectrum analyzer During deployment phase, it is important to verify NB-IoT signal transmission as defined in 3GPP. The R&S FSH supports NB-IoT downlink over-the-air signal measurement. Since the basic intent of NB-IoT is to have a reliable connection, measuring the transmitted signal quality is essential. The spectrum overview shows in-band, guard-band and standalone NB-IoT carrier and DL power boosting. The R&S FSH depicts the signal quality in an alphanumeric view and graphically in a constellation diagram (here the QPSK modulation scheme). Alphanumeric view of decoded signals and signal quality. NB-IoT constellation diagram. Rohde & Schwarz MNT eguide Pioneers in NB-IoT testing 15
Rohde & Schwarz The Rohde & Schwarz electronics group offers innovative solutions in the following business fields: test and measurement, broadcast and media, secure communications, cybersecurity, monitoring and network testing. Founded more than 80 years ago, the independent company which is headquartered in Munich, Germany, has an extensive sales and service network with locations in more than 70 countries. www.rohde-schwarz.com Mobile network testing The company s broad and diverse product portfolio for mobile network testing addresses every test scenario in the network lifecycle from base station installation to network acceptance and network benchmarking, from optimization and troubleshooting to interference hunting and spectrum analysis, from IP application awareness to QoS and QoE of voice, data, video and app-based services. www.rohde-schwarz.com/mnt-nb-iot Meet the experts. Visit the blog. www.rohde-schwarz.com/mnt-nb-iot Regional contact Europe, Africa, Middle East +49 89 4129 12345 customersupport@rohde-schwarz.com North America 1 888 TEST RSA (1 888 837 87 72) customer.support@rsa.rohde-schwarz.com Latin America +1 410 910 79 88 customersupport.la@rohde-schwarz.com Asia Pacific +65 65 13 04 88 customersupport.asia@rohde-schwarz.com China +86 800 810 82 28 +86 400 650 58 96 customersupport.china@rohde-schwarz.com R&S is a registered trademark of Rohde & Schwarz GmbH & Co. KG PD 5215.8712.92 Version 01.01 June 2018 (as) Trade names are trademarks of the owners eguide Pioneers in NB-IoT testing Data without tolerance limits is not binding Subject to change 2018 Rohde & Schwarz GmbH & Co. KG 81671 Munich, Germany 5215871292 5215.8712.92 01.01 PDP 1 en