The end of 2G is inevitable – internationally, we have already seen its discontinuation in the likes of the US and Australia. Even 3G may not be available for long in some countries. In South Africa, we probably have a good few more years but ultimately a replacement technology is needed.
Companies offering services like vehicle tracking and alarm systems, for example, that have built their systems on the 2G network will need to have an alternative. Low power wide area (LPWA) technologies fill the gap between mobile (3G, LTE) and short-range wireless (eg. Bluetooth and Wi-Fi) networks
What will LPWA do?
LPWA technologies will enable the connection of billions of IoT devices onto the Internet. They are designed to provide connectivity to devices and applications that require low speed and low data bandwidth. This will be critical in the development of the IoT applications. The LPWA devices are ideal for applications that have low data transfer rates and don’t need data very often, so will handle small amounts of fairly infrequent data.
IoT devices and sensors will be used in a wide range of industries and applications which will require a large number of low-throughput devices and where a delay in communications will not result in a material loss of service. One of the early use cases is in energy and water meters, where meters do not need to transmit data frequently or in real-time, and can be sited in difficult-to-reach locations.
How will it do it?
The main drivers behind the development of LPWA technologies were to reduce cost (in terms of device as well as deployment) and power consumption, at the same time as increasing coverage and the number of devices that can be connected, compared with cellular and other wireless networks.
These devices will typically be battery powered and not connected to mains power, so most of these technologies promise to achieve up to 10 years’ battery life on a single charge. They incorporate technologies that enable devices to power down when data is not being transmitted to conserve battery life.
There are many competing LPWA technologies in this space but in South Africa they are mainly LoRa, Sigfox and now Narrowband IoT (NB-IoT).
French based Sigfox is one of the early starters in this space. Globally they partner with companies in various countries to roll out
their IoT ecosystem, including platform providers, device and other manufacturers and tech hubs. Their technology uses ultra-narrowband (UNB) modulation in unlicensed frequency bands.
One advantage of Sigfox is that it is one global IoT network and can listen to billions of objects broadcasting data, without the need to establish and maintain network connections. Another advantage is that it uses very low power as there is no signalling overhead and the objects are not constantly attached to the network. Sigfox offers a software-based communications solution, where all the network and computing complexity is managed in the cloud, rather than on the devices.
Based out of California, the LoRa Alliance is an open, non-profit association with 330 members globally among telcos, system integrators, startups and manufacturers. The alliance claims there are live LoRaWAN networks in more than 120 cities.
LoRa technology offers a very compelling mix of long range, low power consumption and secure data transmission. One of the main benefits of this technology is that it allows the creation of both public and private networks and can provide coverage that is greater in range compared to that of existing cellular networks. If there is a coverage issue, it is relatively inexpensive to add coverage privately. It is also easy to plug into the existing infrastructure and offers a solution to serve battery-operated IoT applications.
NB-IoT is a low power wide area network (LPWAN) radio technology standard developed by 3GPP specifically for the IoT, for devices that require small amounts of data and ultra-low power requirements. The cellular networks are embracing this technology and see it as an enabler for mass IoT deployment due to its low power requirements and wide area coverage.
Ultimately, the end devices will have to be as low cost as possible to enable the huge number of IoT devices that are predicted to be connected. Because it uses a network with licensed spectrum, NB-IoT is more secure and less susceptible to interference than unlicensed spectrum LPWA solutions, and it also enables global roaming.
NB-IoT specifically suits battery powered IoT applications that do not move (static installations). It is perceived to have cost and coverage advantages over another evolving technology called LTE-M (also known as LTE-MTC). LTE-M is more suited to applications that require slightly higher throughput and mobility, such as tracking. This is perhaps a better 2G alternative but right now the local cellular networks are focusing on NB-IoT and it will most likely be a while before they will invest in rolling out LTE-M.
There must be uninterrupted coverage in order for IoT applications to work, with coverage over long distances and deep penetration. NB-IoT must therefore provide coverage of remote and rural areas, hard to reach places such as underground locations, and deep inside buildings.
Power spectrum density (PSD) boosting and repetition in NB-IoT can deliver coverage gains of 20 dB when compared with GSM networks, enabling about ten times better area coverage. NB-IoT needs just 200 kHz of bandwidth (hence the name ‘narrowband’) which means it can run adjacent to existing cellular networks. The unit cost of NB-IoT devices is expected to be low and to fall as demand picks up.
While the number of connected devices continues to rise (and is expected to reach 125 billion by 2030), the maturing wireless technologies that support them are also continuing to get a good deal of attention. NB-IoT, LoRa and Sigfox, all low-power, wide-area network (LPWAN) technologies, are often pitted against one another with an expectation for one to be the clear winner. However, if you understand each of the technologies and their features, you will see that there is probably a place for all of them and each can play a role in IoT.
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