Low power wide area network (LPWAN) technologies do exactly what it says on the tin: they have low power draw and provide coverage to wide areas. They are lower cost than mobile networks and have a wider range than short-range wireless networks.
They provide connectivity for devices and applications that require low mobility and low levels of data transfer, such as sensors, and are therefore seen as a key enabler of the Internet of Things (IoT).
A little bit of history
The term low power wide area (LPWA) was coined in 2013 for a class of wireless technology designed for machine-to-machine (M2M) communications (or machine-type communications, MTC, in 3GPP-speak), and was validated as the wireless technology of choice for the Internet of Things (IoT) in 2015, when the 3GPP decided to standardise a number of technologies for different applications.
These are: Narrowband IoT (NB-IoT, aka NB CIoT or LTE-M2), eMTC (aka LTE-M, LTE-M1 and LTE-MTC) and EC-GSM (Extended Coverage GSM). They all use licensed spectrum and are covered in detail in other 5G guides; this guide will focus on the non-standardised LPWANs which do not use licensed spectrum.
What is LPWAN?
LPWAN technologies fill the gap between mobile (3G, LTE) and short-range wireless (e.g. Bluetooth, WiFi and Zigbee) networks, and are designed for machine rather than human communications. Human communications encompass voice, data and video and need high throughput and low latency while the user is on the move to guarantee a seamless user experience. In contrast machine communications, particularly for IoT devices and applications, need infrequent low levels of data transfer with low mobility.
The LPWAN provides the connectivity companies use to deliver their services, and once it’s established it’s straightforward for companies to connect to it and get their own service up and running – the cost depending on the choice of LPWAN. Businesses use LPWANs to create their own secure network and connect their IoT devices, such as sensors for monitoring crops or environmental conditions in a mine.
The low power draw aspect of LPWAN is critical: an IoT device will be of little use if it needs to be charged on a regular basis as we do our mobile phones, or is powered by the mains. LPWAN devices have a long battery life because they transmit only small packets of data at intervals, and the packets are packaged and sent efficiently. They can last for a decade or more on one or two small (think AA, AAA or even watch) batteries. Sensors can therefore be deployed in buildings or difficult to access areas and left alone to transmit data for years.
LPWANs provide a wide area of coverage that is not limited by proximity to or distance between the access points (APs, i.e. base stations or towers). They also do not require line-of-sight communications, although the area of coverage will usually be less in areas with obstacles, such as a city. They therefore require far fewer APs than cellular or other short-range wireless technologies. This enhanced coverage can be achieved through various methods to improve the efficiency of the signal transmission, such as increasing power to a transmitting antenna, the receiver sensitivity or antenna gain (i.e. the efficiency of the antenna converting electrical power to a radio signal).
Low power and wide area are the prime definitions and characteristics of LPWA, but they imply other benefits for IoT applications over cellular or mesh networks. They provide connectivity out of the box for a large number of IoT devices, so that more and different devices can be added to enable companies to scale quickly and address new requirements as the market evolves.
All of the above add up to cheaper cost, which will be vital in supporting and enabling the billions of devices that will be connected in the IoT. The wide area nature of LPWAN means that far fewer base stations are required, reducing the cost of the infrastructure itself and its deployment, maintenance and operation.
Non-standardised LPWANs do not require expensive licensed spectrum but work in public property frequencies that are free to use. LPWAN devices are far less complex than a cellular device like a mobile phone, and need minimal compute power and storage capacity. They are therefore smaller and much cheaper to manufacture and deploy. The running costs are also minimal, consisting of cheap and readily available batteries that will last for years. Lastly, they require little to no maintenance over their lifetime.
These cost savings translate to lower costs for the end user, i.e. the company providing the IoT products and services.
The trade-off for LPWANs is latency. For voice and data communications, latency is measured in milliseconds (ms) but for machine communications it’s measured in seconds (s). This is not a disadvantage: LPWAN has been specifically designed for the infrequent (often one-way) data transmission that most machine communications require.
What are the different LPWAN technologies?
There is no single standard for LPWAN and there are a number of competing technologies and initiatives, both proprietary and open source, standardised and non-standardised. While they share the same characteristics, they work in different ways and provide differing levels of coverage and capacity.
There is no one-size-fits-all and the end-user will select the LPWAN technology that is most suited to their specific use case. Indeed, they are not mutually exclusive, and a company could use different LPWANs for different applications. The following is an overview of the main different non-standardised LPWAN technologies:. The main standardised technology, Narrowband IoT, is covered in a separate guide.
Also, the Random Phase Multiple Access (RMPA) technology heading should strictly be in a different format to the other technology headings as it’s part of the Ingenu section.
LoRaWAN is an open standard with a certification programme to guarantee interoperability that is governed by the LoRa Alliance. Any company can buy LoRa hardware and deploy its own network without going through and paying fees to a centralised authority. However, the underlying LoRa chip needed to implement a LoRaWAN network is proprietary to California-based semiconductor manufacturer Semtech.
Semtech got the technology through its 2012 acquisition of France-based Cycleo, which had developed the technology in 2009. Semtech owns the LoRa IP and manufactures chips for devices and the gateways that connect them, and has licensed the technology to other chipmakers.
Set up in March 2015 to promote the LoRaWAN protocol, the LoRa Alliance is an open, non-profit association with over 500 members globally among telcos, system integrators, start-ups and manufacturers. By early 2018 there were 62 announced public network operators and over 350 ongoing trials and city deployments of the LoRaWAN protocol in more than 100 countries.
LoRa uses the sub-GHz spectrum (868MHz in Europe, 915MHz in the Americas and 433MHz in Asia). It employs a spread spectrum technique to transmit data on different frequency channels and at different rates, so that the gateway can adapt to changing conditions and optimise the way it exchanges data with each device.
A single gateway can communicate with several hundred thousand devices up to 20 miles away in unobstructed environments. In urban environments LoRa can penetrate buildings and achieve a range of several miles.
Data rates range from 300bps to 50kbps depending on the spreading factor and channel bandwidth, while the maximum message length is 243 bytes and it offers effective two-way functionality. Each message is received by all the base stations in the range to improve the transmission success ratio, but it requires multiple base stations, which can increase the network deployment cost.
The most widely deployed proprietary LPWAN technology is Sigfox, which was established in France in 2009 and deployed its first network in mid-2012. By early 2014 it had achieved nationwide coverage in France, and a year later there were Sigfox networks in five countries. Sigfox itself has networks in France, Germany, Spain and the US, but elsewhere networks are deployed and operated by a variety of partners. As of August 2018 there were networks in some 50 countries globally with a target of 60 by the end of the year.
Like LoRaWAN, Sigfox operates in sub-GHz spectrum. It uses Ultra-Narrowband (UNB) technology, which enables highly efficient use of the bandwidth with very low noise levels, and a slow modulation rate to achieve a long range (up to 10km in urban areas, 50km in rural settings and 1,000km in line-of-site applications).
An entire city can be covered with a single base station. The trade-offs are low data rates (up to 2s for a 12-byte transmission) and capacity limits of 150 12-byte uplink messages and four 8-byte downlink messages a day.
The base stations can receive messages simultaneously over all available channels, so the end device randomly chooses a frequency channel to transmit its messages. This simplifies the design of the end device and hence reduces its cost.
There are a wide range of Sigfox radios and modules for devices from manufacturers including Telit and Texas Instruments. Sigfox APs are installed on towers, often on those owned by mobile operators, and Sigfox controls the backhaul communications infrastructure and backend cloud management platform which must be used by – and paid for by – any company wanting to deploy with Sigfox.
San Diego-based Ingenu (formerly On-Ramp Wireless) was formed in 2008 but did not start operating as a public network until 2015, when it announced it would roll out its Machine Network to 30 metro areas in the US by the end of 2016 in the first phase, an area of nearly 100,000 square miles. However, it didn’t come close to this goal: by March 2017 it had covered less than 7,000 square miles.
The Machine Network is now live in 42 US cities, predominantly in the southern half of the country, significantly less than the projected 100 by the end of 2017. Ingenu claims its international partners have network deployments in over 30 countries globally, although it doesn’t give details of the extent of the networks or their locations.
In March 2018 the company shifted its focus to providing its technology on a platform-as-a-service (PaaS) basis, with operation of the US network to be transferred to technology licensees and/or network operators, and manufacturing of its RMPA access points to be undertaken by third parties. The aim is to lower costs and streamline operations, while boosting revenue from operator and licensee agreements and increasing the number of licensees.
Random Phase Multiple Access (RMPA) technology
Ingenu’s proprietary Random Phase Multiple Access (RMPA) technology operates in 2.4GHz spectrum, giving it greater transmission power to allow for a rich signal strength and high coverage per AP. However, the spectrum is crowded and can be subject to interference and propagation loss.
Ingenu claims to have provided coverage of up to 400 square miles per tower in rural Texas, but its range is limited to 5-10km for non-line-of-sight applications. Its uplink capacity can support up to two million devices per tower and the company claims to have customers with devices in the field with a battery life of over 20 years.
Ingenu delivers higher data throughput rates than other LPWAN technologies but with higher power consumption. It has a sweet spot in utilities and oil and gas applications but has also expanded into other IoT applications.
LoRa, Sigfox and Ingenu are the three most established and widely deployed LPWAN technologies, but there are others out there even though they haven’t yet gained much traction as yet. The list is long (and growing) but a couple of open source initiatives are worth highlighting as they are starting to come to the fore.
Cambridge-based Weightless SIG (Special Interest Group) is probably the most advanced. It was founded in 2008 to develop standards for M2M communications in white space (unused TV spectrum) using technology originally developed by Neul (also based in Cambridge and acquired by Huawei in 2014).
It’s a non-profit alliance whose members pay membership fees enabling them to use the Weightless open standard with no royalty fees. It claims thousands of members from over 50 countries. Weightless developed three standards for different use cases which employ different technologies and provide varying levels of packet size and data rates: Weightless-N for unidirectional communications; Weightless-P, an ultra-narrowband protocol for bidirectional communications now known simply as Weightless Technology; and Weightless-W, also bidirectional and using unused TV spectrum but with a shorter battery life than the others.
Having narrowed its focus to Weightless Technology, the alliance may now start to make some meaningful headway. The first hardware, manufactured by Taiwan’s Ublik, began shipping in 2017. Claiming to have pre-order customers in 20 countries as of September 2017, the hardware consists of base stations, end device modules and software to enable testing, evaluation and development.
The DASH7 Alliance manages and develops the open source DASH7 protocol specification, which originates from ISO 180000-7 and was developed by California-based Haystack Technologies. Version 1.0 of the specification was released in October 2015 and v1.1 in early 2017.
LPWAN in the UK
The UK has been a slow developer and adopter of LPWAN technologies and lagged behind much of the rest of the world in the rollout of the technology. No UK company was involved in founding the LoRa Alliance, and although Sigfox signed up Arqiva as its UK partner in 2014 little progress was made in comparison with other countries.
By mid-2017, the network was available in 11 cities, equivalent to around 35% population coverage. As a result, Sigfox appointed WND (its partner in Latin America) to accelerate rollout in the UK. It has a stated goal of up to 95% population coverage by 2019, including rural areas, and by mid-2018 had achieved 45%.
The first Weightless-N network went live in London in mid-2015 but was more of a testbed than a commercial deployment. London-based Nwave Technologies, which deployed the network having contributed the technology on which Weightless-N is based when it joined the SIG in 2014, appears to have morphed into a smart parking management system.
In order to address the issue, in 2016 government bodies IoTUK and Digital Catapult launched innovation programmes focused around LPWAN. The idea was to give UK businesses access to the technology so they could develop LPWAN-based IoT products and services, kickstart the rollout of a nationwide LPWAN and generally build awareness around the technology.
IoTUK selected partners to deliver six regional LPWAN ‘Boosts’, while Digital Catapult launched the Things Connected LPWAN in London in January 2017. At launch it had around 20 base stations, which had been expanded to around 50 in greater London as well as nearby locations including Cambridge, Milton Keynes and Watford. In November 2017 Digital Catapult selected three regional partners to extend the Things Connected network in the North East & Tees Valley, Northern Ireland and Bournemouth.
There were no restrictions on what LPWAN technologies could be used, although those requiring licensed spectrum were not suitable. Things Connected and most of the regional Boosts plumped for LoRaWAN due to the ready availability of equipment, the open source technology, and a growing grassroots community in the UK.
It was envisaged that Things Connected would incorporate other technologies at a later date, and Sigfox is now being integrated into the network. Both LoRaWAN and Sigfox are being deployed in Sunderland and Ulster, while the Bournemouth network is being deployed in conjunction with WND and will comprise 30 Sigfox base stations.
In June 2018, Things Connected agreed to join forces with The Things Network (TTN), a Netherlands-based global community of more than 40,000 active members building a public LoRaWAN-based network. There were 63 TTN communities in the UK with over 700 members and 300 base stations, which add to the 100-plus Things Connected base stations to create the largest free-to-use LoRaWAN network in the country.
Mobile operators are already deploying LPWAN technologies alongside their cellular networks, but again progress in the UK has been slow. BT, parent company of EE, deployed some of the LoRaWAN base stations in the original Things Connected network and also has some Sigfox deployments.
O2’s parent company Telefonica invested in Sigfox in February 2015 and two years later struck a global deal to integrate Sigfox technology into its managed connectivity platform, but doesn’t appear to have done anything in the UK to date. Meanwhile Vodafone has eschewed the non-standardised versions in favour of NB-IoT, with commercial networks in six countries and trials in two more as of early 2018. Again, nothing has been announced for the UK.
We’re still in the early stages of LPWAN in the UK but commercial services are already available, and recent developments should pave the way for more products and services to come to market using LoRa and Sigfox technologies.
It’s less likely that we’ll see any Ingenu deployment of any size. The company has clearly struggled with its business proposition in its core US market and international developments have been thin on the ground. One area where it might be successful could be in the North Sea oil and gas fields, given Ingenu’s success with partner WellAware in Texas and announced deployments focused on the industry in the Middle East and Nigeria.
Other emerging protocols and technologies could also find their mark, but for now Sigfox and LoRa have the edge and are likely to account for the bulk of deployments in non-licensed spectrum in the UK.