What is an IoT (LPWAN) network?
An “internet of things” network is a low-power, wide-area network designed for machine-to-machine applications. These networks purposefully transfer data at low speeds in order to maintain low power consumption and extend battery life. LPWAN networks enable the connectivity of devices that require much lower bandwidth than what is required of most standard home devices, and must be scalable enough to accommodate Gartner’s estimated 20.8 billion “things” that will be connected by 2020.
The purposes of LPWAN networks are not to provide the fastest speeds for the most demanding applications, rather, the goal is to provide a low-power blanket for small devices like sensors and smart meters. Those devices take readings and send the information to another system that can process the results and act accordingly. Most uses will be in the industrial sector, whereas access technologies like Bluetooth, Zigbee and Wi-Fi are geared toward more demanding applications.
LPWANs enable devices to connect over ranges of around 15 miles, while delivering battery life of up to 10 years. Low cost, low power and security are the three pillars of building an IoT network.
But what might be most intriguing about a low-powered wireless network is it’s designed to operate at much lower costs than LTE or 3G networks. Because of this, several IoT providers are entering the market with the hopes of becoming the go-to source for dedicated IoT communication.
Vertical markets for IoT networks?
- Energy – smart metering.
- Health care – patient monitoring, fitness tracking.
- Transportation – automated vehicles, smart roadways.
- Factories – automated processes.
- Buildings – connected stadiums, dynamic environments.
Many options, different flavors
Sigfox
French company Sigfox deploys wireless networks designed to connect to low-energy devices. The networks use ultra-narrow band, unlicensed sub-1 GHz bands and standard radio transmission methods. Sigfox claims UNB offers “a great resistance to jamming and standard interferers,” something one must be leary of with unlicensed spectrum.
The network operator wants to deploy its own IoT network throughout the world and become a global LPWAN carrier. The company also is working with regional operators to roll out networks, with all of the data received going back to Sigfox servers before being sent to customer devices. Sigfox wants to run the core service behind every device. That comes with added risk, but the $115 million in investment it has received shows they aren’t the only ones who think it can be done.
Sigfox said its clients need only three things to get its IoT environment running:
- A Sigfox-ready module or transceiver.
- A valid subscription. Development kits and evaluation boards come with an included one-year subscription.
- Be in a coverage area.
The company’s network is currently available in 22 countries, covering 1.3 million square kilometers and 340 million residents. In June, Sigfox announced it would expand its coverage to more than 100 U.S. cities, hoping to increase the $12 million in revenue from 2015.
“The most important thing for people to understand is that the IoT base is huge and there will be multiple types of connectivity. Also, it is crucial to understand the positioning of the different solutions and here nobody has a similar positioning as Sigfox,” Thomas Nicholls, EVP of communication at Sigfox, told Industrial IoT 5G Insights. “There will not be one actor winning everything because the different accesses cater for different types of applications. And there are many use cases that can only be addressed by other solutions than Sigfox.”
LoRaWAN
LoRaWAN is an open-source LPWAN infrastructure created by the LoRa Alliance that, unlike Sigfox, allows other companies to create their own IoT networks based on its technology specifications.
The technology is designed to enable a gateway or base station to cover entire cities or hundreds of square kilometers. Range depends on the environment or obstructions in a given location, but LoRa claims its network has a link budget, or the factor in determining range of a given environment, greater than any other standardized communication technology.
Communication between end devices and gateways is spread out on different frequency channels and data rates. Because it uses a chirp spread spectrum approach, communications with different data rates do not interfere with each other and create a set of “virtual” channels increasing the capacity of the gateway. LoRaWAN data rates range from 0.3 to 50 kilobits per second.
There are three different types of LoRaWAN classes, each with its own way of receiving and transmitting signals.
- Bidirectional end-devices (Class A): End-devices of Class A allow for bidirectional communications whereby each end device’s uplink transmission is followed by two short downlink receive windows. The transmission slot scheduled by the end device is based on its own communication needs with a small variation based on a random time basis (ALOHA-type of protocol). This Class A operation is the lowest power end-device system for applications that only require downlink communication from the server shortly after the end device has sent an uplink transmission. Downlink communications from the server at any other time will have to wait until the next scheduled uplink.
- Bidirectional end devices with scheduled receive slots (Class B): In addition to the Class A random receive windows, Class B devices open extra receive windows at scheduled times in order for the end device to open its receive window at the scheduled time it receives a time synchronized Beacon from the gateway. This allows the server to know when the end device is listening.
- Bidirectional end devices with maximal receive slots (Class C): End devices of Class C have nearly continuously open receive windows, only closed when transmitting.
LoRaWAN network architecture is typically laid out in a star-of-stars topology in which the gateway is a transparent bridge relaying messages between end devices and a central network server in the backend. Gateways are connected to the network server via standard IP connections while end devices use single-hop wireless communication to one or many gateways. All end-point communication is generally bidirectional, but also supports multicast-enabling software upgrade over the air or other mass distribution messages to reduce the on air communication time.
Senet
Where LoRa is a set of technologies that allows for an ultra-low powered network, Senet is a network provider of LoRa-based technology. It is currently the only public provider of LPWAN using LoRa modulation. Senet networks have expanded to tens of thousands of sensor nodes, 200 towers and more than 100,000 square miles. Last year, the company developed a network in San Francisco to facilitate the expansion of IoT services.
Earlier this month, Senet hit a milestone in providing coverage to 100 U.S. cities. According to the company, plans call for doubling the number of cities covered throughout the remainder of 2016.
“We continue to execute on our plan of building out the network in the U.S. and are thrilled to have reached this milestone,” said George Dannecker, president and CEO of Senet. “This clearly demonstrates our leadership position in building and operating [low-power wide-area networks] at scale. However, network coverage and growth are only one piece of the puzzle in commercializing high-[return on investment] IoT applications, which is why we will continue to focus on helping these applications get deployed more quickly and will be making further investments and announcements in that area.”
LTE CAT-M
Everyone is familiar with the ultra-fast, bandwidth intensive LTE network. But it is LTE-based Cat-M technology that is set to bring the wireless standard into LPWAN territory. Cat-M is considered a “cellular IoT technology” that falls under 3GPP standardization. It differs from Sigfox and LoRa in that it uses licensed spectrum, instead of open, unlicensed spectrum. This allows it to avoid potential interference that competitors in the unlicensed spectrum might face down the road.
Arne Schaelicke, who leads LTE marketing for Nokia’s Mobile Networks, told Fierce Wireless why standards like CAT-M make sense moving forward.
“Sigfox, LoRa and Ingenu use unlicensed spectrum. As everybody could use this spectrum, there could emerge even more competing technologies,” Schaelicke said. “The more technologies and the more devices connect on this spectrum, the higher the risk of interference. Only cellular IoT technologies on licensed spectrum will allow for reliable IoT connectivity in large areas in the long term.”
Cat-M is the second generation of LTE chipsets meant for IoT. The first generation, Cat-M1 LTE, enabled reduced power consumption and cost by capping download speeds at 10 megabits per second down and upload speeds to 5 Mbps. A later release of Cat-M1 capped download speeds to the 200 to 300 kilobits per second range. Cat-M2 will further decrease power consumption in order to use limited bandwidth and keep low-power devices efficient. It will reduce throughput down to 10 to 30 kilobits per second, with bandwidth requirements at 200 kilohertz.
In a February report by RCR Wireless News, Sequans CEO Georges Karam spoke about the reasons carriers turn to LTE for IoT.
“Basically the market today is using Cat-1 for all those applications because they have nothing else,” Karam said. “All the applications of [machine-to-machine] – they need to move from 2G to something else and the best they can do is to move to Cat-1, so we are seeing Cat-1 used on all kinds of applications whether high speed or very low speed. If you are willing to pay then why not? It is a good solution.”
Mobile carriers Verizon Wireless and AT&T Mobility have both expressed interest in using Cat-M LTE for their networks. In February, Verizon Communications’ chip partner Sequans announced the release of a Cat-M chipset, and earlier this month AT&T said it would be testing out CAT-M1 tech, which may be a solution for those relying on the company’s soon-to-be shutdown 2G network. The carrier laid out the following benefits of using Cat-M technology:
- Access to low-cost module technology.
- Extended battery life of 10 years or more for enabled IoT devices.
- Enhanced LTE coverage for underground and in-building areas that challenge existing coverage.
Outlook
It isn’t easy to predict what will become of the emerging IoT networks. One thing we do know is that the upcoming “5G” network will play a role in IoT in one way or another. The grand vision of 5G, and a major technological challenge, is an air interface so flexible that it can support everything from bandwidth and latency intensive applications like remote industrial control to the low-power, low-throughput transmissions sent over IoT networks.
