The Internet of Things (IoT) offers the potential to connect up billions of devices around the globe with infrastructure that link directly to enterprise systems. Connecting up sensors to monitor all kinds of equipment across the IoT gives tremendous advantages in providing data about smart buildings, smart cities, tracking, monitoring and utilities. With this data, machine learning can provide key insights into the operation of all kinds of systems, optimising their performance and even predicting when they will need maintenance.
Over 75 billion IoT devices are expected to come online by 2025 according to market research firm Statista. However, many of these are in rural or remote locations that lack traditional connectivity networks.
One of the key technologies for connecting up these devices is low power wide area networking (LPWAN). These networks operate in the sub-GHz Industrial, Scientific and Medical (ISM) frequency bands at 868MHz in Europe and 915MHz in North America. These frequencies allow long distance connections, often several kilometres, to connect smart sensor nodes to a gateway. This gateway can feed the data back into the internet and enterprise systems to enable detailed analysis elsewhere in the world.
One of the leading LPWAN technologies is Semtech’s LoRa devices. This was developed in 2009 with a specific modulation called chirp spread spectrum (CSS) that has a high level of immunity to noise to achieve both low power and long-range capability. LoRa can support low power transmission of data at rates up to 50 Kbit/s, although data rates of 1kbit/s to 5kbit/s are the norm to extend the battery life.
Using this protocol enables battery life of up to 10 years, removing the need for costly replacements and cutting OPEX costs, making the deployment of smart sensor networks at scale possible. The low power of the transceiver chips means smart sensors can also be powered by energy harvested from the environment via solar panels or even from the surrounding RF radio waves.
On top of the protocol at the physical layer is the LoRaWAN network architecture. This is a star-of-stars topology where gateways relay messages between end-devices and a central network server.
The wireless communication takes advantage of the long-range characteristics of the LoRa physical layer allowing a single-hop link between the end-device and one or many gateways. All modes are capable of bi-directional communication, and there is support for multicast addressing groups to make efficient use of spectrum during tasks such as Firmware Over-The-Air (FOTA) upgrades.
This has led to LoRaWAN as the implementation of LoRa becoming the most widely used LPWAN technology in the unlicensed bands below 1GHz, providing battery powered sensor nodes with kilometres of range for the expanding applications across the Internet of Things.
A key area for this low power, long range connectivity is smart cities. The ability to place wireless smart sensors for air quality, traffic density and transportation wherever they are needed across the urban infrastructure can give key insights into the activity of the city. The robust, low power nature of the protocol allows local authorities to run a cost-effective network with sensors in the right place, whether powered by local power lines, batteries or solar panels.
This extends into smart retail with sensors in shops to monitor occupation and keep people safe for COVID-19 protection, and even to products, allowing high value items to be tracked from the factory to the customer. With a network throughout the smart city, this tracking can extend as far as the networks reach.
For the oil and gas industry for example, the data can be analysing the performance of equipment on oil rigs, on pipelines or on electricity pylons in the harshest of environments. This can provide both sensor data monitoring pipelines and can also be used for predictive maintenance, using machine learning to identify patterns in the data that indicate a machine will fail in the future. This allows equipment to be repaired or replaced during scheduled maintenance rather than failing at a random time.
LoRaWAN is managed by the LoRa Alliance as an open standard, and the Alliance includes 156 LoRaWAN network operators in 171 countries, as well as suppliers of LoRa chips, transceiver and sensor boards and gateways. This open ecosystem of network operators and technology suppliers enables a wide range of applications, often with thousands of sensor nodes spread around an area, perhaps with kilometres between them.
A guide to sensor technology in IoT
Future developments
The success of LoRa for long range networks is being repeated with a new protocol. Called Long Range – Frequency Hopping Spread Spectrum (LR-FHSS), this extends support for LoRa networks with direct data links to satellites. LR-FHSS improves the noise immunity even further, allowing the sub-GHz signals to be picked up by the satellites in low earth orbit (LEO).
Using sensor nodes to connect to these satellites allows existing networks to expand quickly and easily without replacing the existing network infrastructure. The terrestrial and satellite modulation schemes can coexist at the same time in a gateway or the network server, and the different gateways can coexist in the same network.
These satellites carry gateways using LoRa as payloads that handle the LPWAN messages natively using the same modulation schemes, relaying the data in near real time from all-around the world. This allows satellite operators to reuse terrestrial gateway architectures or develop their own Software Defined Radio system (SDR) to implement the modulation schemes.
This native approach avoids having to consolidate and convert the data into IP packets, which takes more time and power consumption, and ensures that every data packet arrives at its destination with a time stamp. This is key for enterprise systems to be able to manage the volume of data.
The satellite connection is also of increasing interest to applications such as smart metering. The LR-FHSS modulation allows more indoor penetration for end nodes, particular smart meters that may be in less accessible places in a building. Having a direct connection to a satellite network also avoids the need for building or extending a network of gateways.
At least five satellite LPWAN networks have launched or are in the process of launching, providing a wide range of different engagement models, from direct connections to gateway links. This gives enterprise users multiple options for connecting up devices across the IoT to capture, analyse and act upon the data.
As technology continues to evolve, and new solutions are developed to suit specific needs, it’s important that businesses and individuals choose the right solution that with not only scales as technology develops but has global reach. Download this ebook to learn more about how Semtech’s LoRa technology and the LoRaWAN standard enable flexible, secure and low-cost IoT solutions and network infrastructure for smart cities.
