Given the fact that there are close to a billion cellular Internet of Things (IoT) devices deployed today, and with introduction of 5G, will latter replace all the existing IoT technologies and will the current investment in IoT become obsolete? The simple answer is ‘No’. To understand this response a little better, Adrian Taylor delves a little deeper into existing IoT technologies.
The IoT is growing exponentially with some forecasts estimating the total number of IoT devices to be north of 25 billion come 2025. For the layperson, IoT devices are small, low-powered devices that generate infrequent low-volume traffic, such as smart meters. While that’s generally true, IoT devices do cover a much larger segment. In fact, you could classify the IoT into two categories – wide area IoT and short range IoT.
Wide area IoT devices are generally low power and transmit infrequent short bursts of data over a low power wide area network (LPWAN). These devices are generally installed in remote areas with no external power supply (ie they’re running on batteries) and are therefore expected to be very power efficient. LPWANs can work in both the licensed spectrum as well as the unlicensed spectrum.
Two of the most common LPWAN technologies that work in the unlicensed spectrum are SigFox and long range wide area network (LoRaWAN). Those that work in the licensed spectrum are narrowband (NB) IoT and LTE-M or LTE machine-type communication, also known as Cat-M1, both of which are specified by 3GPP in Release 13 and are collectively known as cellular IoT.
SigFox is a proprietary technology owned by a French company of the same name. It’s ultra narrowband technology enabling wireless signals to pass freely through solid objects making it suitable for underground and in-building operations. SigFox operates in the 868 MHz band in Europe and the 902 MHz band in the US. It’s designed to support arrays of devices likely to send small amounts of data (100 bytes per second) in short bursts (eg parking sensors and utility meters). As at the tail end of 2018, a little more than 60 countries had SigFox-based deployments.
LoRaWAN is a spread-spectrum technology with a wider band than SigFox. LoRaWAN is actually a medium access control protocol running on top of the Long Range (LoRa) physical layer protocol operating in unlicensed bands such as 433 MHz and 868 MH in Europe and 915 MHz in Australia and North America. LoRaWAN technology is licensed by SemTech and has been developed under the LoRaWAN alliance since 2015. As of end of 2018, about 100 countries had LoRaWAN-based IoT deployments.
Short range IoT
Before we jump into cellular IoT, let’s briefly look at short range IoT devices. These generally need higher power, but still significantly lower than most smart phones, and exchange higher amounts of data. Due to the higher power requirement, these devices either need to be frequently recharged or require an external power supply source.
These devices can be further divided into personal area network (PAN) or local area network (LAN). PAN IoT devices have a range of a few feet. The most common technologies connecting these devices are Bluetooth, ZigBee and 6LoWPAN or IPv6 low-powered wireless personal area network.
The most common PAN IoT devices are headphones and fitness tracking devices, etc. LAN IoT devices have a range of hundreds of feet in general and use some version of 802.11 wireless LAN technology for the underlying connectivity. PAN IoT devices generally run on rechargeable batteries, while LAN IoT devices run on both rechargeable batteries as well as external power sources.
The most common LAN IoT devices are security cameras and home appliances such as refrigerators, etc. A single device can be part of both PAN as well as LAN IoT networks. Such a device could aggregate information from a PAN IoT network into a LAN IoT network, which could then connect to a WAN or the Internet through an IoT gateway.
Per Ericsson’s Mobility Report in June 2019 stated that wide area IoT devices, numbering at about one billion, make up a little more than one-tenth of all IoT deployments today and are growing at a 27% CAGR to reach 4.5 billion devices by 2024. Short range IoT devices make up about 90% of deployments and are growing at a 15% CAGR to about 18 billion devices by 2024. Short range IoT devices are going to continue to exist in the market in the foreseeable future.
Wide area IoT devices are going to see exponential growth, especially so with the introduction of 5G service-based architecture (SBA) core, which will scale much more compared to the 4G LTE packet core. Similarly, we expect LPWAN deployments based on unlicensed spectrum technologies such as SigFox and LoRaWAN to continue to exist and proliferate, albeit at a much lower rate than cellular IoT.
Current cellular IoT technologies
Cellular IoT technologies, NB-IOT and LTE-M are deployed as part of the LTE network and expected to work with 5G networks using the non-standalone (NSA) architecture. In 5G NSA, the radio interface will still be LTE-based, while the core network will be 5G SBA.
As 5G new radio (NR) technology for IoT in Release 16 and beyond is developed, we will start to see 5G NR-based IoT devices deployed in standalone (SA) mode with the 5G SBA packet core.
Before we go any further, one question that usually comes up is why we need NB-IoT and LTE-M as two different technologies in Release 13. LTE-M supports lower device complexity, massive connection density, low device power consumption, low latency and provides extended coverage, while allowing the re-use of the LTE installed base. NB-IoT is characterised by improved indoor coverage, the support of massive number of low throughput devices, low delay sensitivity, ultra-low device cost, low device power consumption and optimised network architecture.
This makes them sound awfully similar. However, there are some notable differences:
*LTE-M supports a higher bandwidth [1.4 MHz with data rates of up to 1 Mbps], while NB-IoT supports lower bandwidth [200 MHz with data rates < 100 Kbps]
*LTE-M supports device mobility, while NB-IoT does not
*LTE-M supports voice traffic using VoLTE, while NB-IoT is restricted to data only
*LTE-M works at a higher frequency band, while NB-IoT works in a lower frequency band making it excellent for indoor uses, while LTE-M may not be as good for indoor use
*LTE-M has a much lower latency (50-100 ms) when compared to NB-IoT, which is usually 30 to 100 times of LTE-M at (1.5 to 10 s).
Service Capability Exposure Function (SCEF) is the new entity added into the LTE network in Release 13. To help meet the low power requirements for LTE-M and NB-IoT, the power-hungry protocol to establish IP data bearers has been replaced by extending the non-access stratum (NAS) protocol to allow small amounts of data to be transferred over the control plane. In this case, the IP stack isn’t necessary, so this type of transfer has been named Non-IP Data Delivery (NIDD).
3GPP-defined SCEF to be the interface for small data transfers and control messaging between enterprises’ IoT application servers and the operator’s core network. SCEF provides APIs to the enterprises for the small data transfers and control messages and uses 3GPP-defined interfaces with the network elements in the operator’s core network to perform its functions. Release 13 also supports IoT IP data delivery with NAS control plane.
Network Exposure Function
In a 5G SBA core, Network Exposure Function (NEF) provides small data delivery service similar to the Non-IP Data Delivery (NIDD) service of 4G SCEF, exposing APIs to application servers. NEF is the interface for small data transfers and control messaging between enterprises’ IoT application servers and the operator’s 5G core network.
In summary, currently deployed LTE-M and NB-IoT devices will connect to the 5G SBA core in non-standalone mode as the 5G SBA core is deployed. Most of the cellular IoT deployment today is with the 4G network, providing device density of about 60K devices for every square kilometre.
Massive IoT deployment requirements in 5G call for device density to be scaled to a minimum of one million devices for every square kilometre. 3GPP is working on enhancements to 5G technical specifications to arrive at this density in Release 16 (which is expected to be completed by June 2020) and Release 17 (slated for completion by the end of 2021 or early in 2022).
Adrian Taylor is Regional Vice-President of Sales at A10 Networks