As the Internet-of-Things (IoT) continues to connect people, space and things at a massive scale, two standards in the world of licensed spectrum, LTE-M and NB-IoT, have emerged rapidly as the low-power-wide-area (LPWA) victors that are here to stay. It is easy to find ourselves meandering in this world of IoT trying to make sense of these technologies in order to understand their applicability for various enterprise IoT solutions, including commercial real-estate (CRE).
To understand the depth of penetration and evolution of LPWA in the licensed spectrum, as of this date, there are thirty-four (34) LTE-M and eighty-seven (87) NB-IoT network deployments, globally1. Out of these commercially launched networks, most of North America, Western Europe, Japan, South Korea, Australia and parts of South America have both LTE-M and NB-IoT networks. However, the majority of Asia, Eastern Europe, and parts of Africa have deployed only NBIoT networks2. From the device point of view, there are currently sixty-eight (68) LTE-M and eighty-nine (89) NB-IoT modules available through all major module vendors globally1.
Ericsson had aptly dissected the world of IoT into two polar categories – Massive IoT and Critical IoT3. Massive IoT defines the applications that require low cost, low energy, small data volume, in massive numbers. In contrast, Critical IoT is defined by ultra reliable, very low latency, very high availability application requirements. Most LPWA technologies are targeted for Massive IoT. Therefore, designed as LPWA technologies themselves, LTE-M and NB-IoT are no different – they are actually standardized cellular network technologies to support massive IoT over the licensed spectrum.
Then the question is, if both technologies are designed to support LPWA, should their applications be similar? We discussed a framework for choosing the right LPWA technologies based on application characteristics in a separate paper in the Connected Real Estate magazine in the past4. This paper will focus on the similarities of NB-IoT and LTE-M, their advantages and their subtleties that will provide further guidance in application decisions.
HOW ARE LTE-M AND NB-IOT SIMILAR AND WHAT ARE THEIR ADVANTAGES?
LTE for Machine-Type Communications (LTE-M) is a LPWA technology that allows extended coverage with low device complexity while reusing the existing LTE installed base. It improves device battery life to more than 10 years, depending on the use case, while driving the cost of modules lower. In comparison to 3G or GPRS modules, LTE-M modules are 20-25% cheaper.
Narrowband Internet of Things (NBIoT) is the latest technology in the foray of LPWA, and has been designed to improve spectrum efficiency, system capacity, as well as power consumption. Its physical layer signal is based on Direct Sequence Spread Spectrum (DSSS) modulation, which helps to reduce interference, facilitating deep coverage (e.g. underground, enclosed spaces). Furthermore, it offers extended coverage to meet rural requirements, while aiming for ultra-low device complexity as compared with other cellular devices.
Both technologies support very low in power consumption – a battery life in excess of 10 years, depending on the frequency of communication and message optimization factors for individual applications. The messaging protocol for each technology is optimized for brief messages – about the length of an SMS.
Device requirements have been simplified to support simple devices, stripping off requirements for traditional cellular devices like cellular phones in order to have a very low module and device unit cost. With the increasing scale of LPWA, the connectivity modules will eventually cost between $5 – $8 US dollars. Their coverage factors have included both indoors and outdoors, in previously unreachable locations, and often beyond power sources.
Advantages of both LTE-M and NB-IoT over other LPWA technologies of the unlicensed spectrum are significant in terms of security, reliability and seamless integration. Similar to the majority of other mobile networks, both LTE-M and NB-IoT technologies benefit from the inherent security and privacy features of the mobile networks, such as user identity confidentiality, entity authentication, and mobile equipment identification.
“An interesting advantage of LTE-M and NB-IoT is bi-directional data with reliable delivery, which is enabled by the inherent data integrity feature of the mobile networks.”
Unlike unlicensed spectrums, standardized mobile networks offer four layers of security. The first two of these security layers are the licensed spectrum itself, which is controlled through standardized access, and the unique subscriber identification module (SIM) technology. On top of these comes the supplemental security method adapted by individual network providers. In this category there are many provider-offered features, such as dedicated virtual private network (VPN) for enterprises, private access point names (APN) for enterprises, IP Whitelisting, and strict service selection control (e.g. devices may be allowed to use SMS but not data), to name a few. Lastly, the application providers or even the network operators may provide application level security.
An interesting advantage of LTE-M and NB-IoT is bi-directional data with reliable delivery, which is enabled by the inherent data integrity feature of the mobile networks. Both of these LPWA technologies allow the network to transport user data within signaling messages encapsulated in what is known as Non-Access Stratum (NAS) signaling. NAS transports both IP and non-IP user data.
Another powerful advantage of the mobile LPWA is remote device update capability using over-the-air (OTA) feature, which is quite limited as a capability in the technologies of the unlicensed spectrum. By leveraging updates of security keys, device configurations, and firmware applications remotely over-the-air, enterprises not only address operational and logistical challenges, but also prevent revenue-impacting downtime, and unnecessary manual operations costs.
Lastly, both technologies are usually integrated into a mobile operator’s unified IoT platform, facilitating seamless backward and forward-compatible integration of connectivity and device management capabilities across technologies.
GREAT, BUT HOW ARE THEY DIFFERENT?
A common misconception for both LTE-M and NB-IoT is that they both are easily compatible with the current LTE networks, reusing existing cellular infrastructure wherever possible. In reality, while both technologies can co-exist with 2G, 3G and 4G mobile networks, only LTE-M can truly reuse the LTE network. NB-IoT requires infrastructure changes in order to work with the LTE network. Therefore, for application deployment considerations, LTE-M has comparatively greater network spread. This is also true in terms of global implementation. Depending on the network provider’s individual situation, LTE-M may have the opportunity for global deployment using a single SIM, whereas NB-IoT may be restricted to local implementation only, as its embedded SIM (eSIM) might target the local network.
Although designated as an LPWA technology, LTE-M actually has the capability of features like voice support and mobility that really set it apart from NB-IoT. LTE-M applications can support voice integration using voice over LTE (VoLTE) technology. The true distinction between the two technologies then boils down to device capability sets – while LTE-M are targeted for broader low powered application, possibly requiring voice support and mobility, NBIoT is truly meant for devices with ultra light capability set, such as individual sensors and actuators.
LTE-M offers mobility whereas NBIoT is really useful for fixed devices. NBIoT’s low interference and deep coverage factors boost its coverage capability, as the signal can serve in-building applications where traditional LTE signals are not easily penetrable. Naturally, many CRE applications like smoke alarms, CO sensors, water level sensors, and a myriad of other sensors from various in-building applications can take advantage of NB-IoT.
NB-IoT uses limited bandwidth spectrum and provides more densification (i.e. coverage with high density) compared with LTE-M – this is another reason why NB-IoT suits the applications with locally concentrated static devices, such as in-build CRE applications.
Since NB-IoT uses UDP (User Datagram Packets) protocol to support low power consumption, a common misconception is that the data can be visible by 3rd parties; and therefore LTE-M offers better encryption. However, due to carrier supported NAS signaling, Private APN, or dedicated service selection features of the mobile network, security factors are very comparable between the two technologies.
WHAT ABOUT 5G? WOULD IT REPLACE LTE-M AND NB-IOT?
According to Global System for Mobile Communication (GSMA), LTE-M and NB-IoT are both part of the 5G family of standards and can operate with 5G NR band. Both of these technologies will continue to co-exist with 5G. Further, the standards body, 3GPP has made both of these technologies forward-compatible in order to fulfill 5G’s densification requirement of 1million devices per square kilometer area. In reality, 5G in its millimeter-wave implementation, is designed to address Critical IoT. Therefore, LTE-M, NBIoT and 5G are really complementary technologies, and here to stay in order to support long enterprise lifecycles for a wide array of IoT applications, including those of CRE vertical.
WHAT DOES THIS MEAN FOR MY CRE APPLICATION?
The majority of the commercial real-estate applications requiring deep in-building penetration, such as smoke alarms, smart locks, or other types of independent sensors would benefit from NB-IoT technologies. Not only are they low cost devices requiring low cost solutions, but these types of applications would also require low data rates while operating at high densification. However, there will be other applications that will benefit from the features of LTE-M, particularly the ones that may require voice communication, or have multi-national deployment needs, such as security alarm panels, security cameras, vending machines, and in-building electric vehicle (EV) charging stations. As LPWA technologies, both LTE-M and NBIoT offer similarities as well as unique value propositions. Ultimately it is important to understand their nuances in order to make a right deployment strategy for individual CRE applications.
About the author
Projit Aon leads product development at a stealth-mode startup and an expert in IoT technologies. He helped to build and scale Verizon’s Cellular IoT Platform, Thing- Space. Projit can be reached at firstname.lastname@example.org.