Image source: Microchip
Did you know that Tata IoT-enabled 98% of India’s landmass in three months? How’s that for a fast rollout. This interesting fact is one of many that came to light during the 8th LoRa Alliance All-Member Meeting and workshop held in Philadelphia from June 12-14.
Many wireless technologies are available to connect sensors to the cloud or a local server: Bluetooth, LoRaWAN, NB-IoT, SigFox, Wi-Fi, zigbee, Z-Wave, and the list goes on. However, LoRaWAN (long-range, wide area network) has a distinct set of characteristics that help it stand out:
- It has an open architecture.
- It operates in unlicensed bands.
- The link budget is 150 dB.
- It is specifically designed for low power and long range.
- It has two layers of security – network and application session keys.
- By using spread-spectrum technology, it operates below the noise floor.
- It uses simple star network topology instead of mesh.
- Any sensor communicates with any reachable gateway and the network server decides optimum path.
- It allows secure, over-the-air (OTA) updates (Figures 1a and 1b)
- Connections get geometrically better as more gateways are added.
Figure 1a. Kerlink demonstrated over-the-air updates for LoRaWAN using three nodes (bottom left) connected to a gateway (just left of shot). (Image source: ClariTek, LLC)
Figure 1b. This screen shows the over-the-air update using a photograph (that’s me on the upper left corner) as the data file to show it was for real. (Image source: ClariTek, LLC)
This is quite a list, and most wireless interfaces have one or more of these features or characteristics. However, for IoT solution providers looking for a relatively simple and fast path to sensor-enabling customers over a wide geography, LoRaWAN seems to be a good option.
Take the open architecture and the unlicensed band operation, for example. SigFox also operates in the unlicensed spectrum, but it’s a walled-garden, where users are subject to whatever SigFox decides to be the right path forward. Nothing is wrong with that, of course, it’s simply a choice and “peace-of-mind” thing. The analogy is Apple iOS vs. Google Android. Users can be pretty sure Apple devices will interoperate and for that peace of mind, the cost is reliance on a single vendor’s ecosystem. There’s a reason Android-based phones are outselling iOS: freedom to innovate.
This freedom puts the onus on developers to ensure interoperability. For LoRaWAN, the LoRa Alliance is making interoperability certification a priority and expects it shouldn’t take more than one day to test devices once it’s in place.
In the case of Narrowband-IoT (NB-IoT), this operates in licensed spectrum, much of which is owned by wireless operators, so cable operators need their own viable alternative. For developers and solution providers, systems that need to run in operator-owned spectrum means getting both FCC certification as well as carrier certification. The former is costly and applies to unlicensed devices, of course. The latter, operator certification, is getting easier as operators recognize the value of enabling IoT solution providers as quickly as possible, but it’s still a time, cost and design-consideration factor.
To make the point about how quickly cable operators can cover a city, the LoRa Alliance used the gathering in Philadelphia to announce that Comcast had rolled a city-wide LoRaWAN IoT network with only a handful of gateways. The advantage cable operators have is that they can use their strands of cable to host the gateways, so there are no extra easement charges. The goal of any new wireless technology rollout is to take advantage of currently installed assets to host the equipment, including cable runs and poles, towers and office buildings.
Efficient, cloud-based intelligence
While there is a lot to discuss about LoRaWAN, one feature that comes to the fore is its network structure. The gateways can range in cost from $100 for an indoor gateway to $1,000 for external systems, depending on how rugged it needs to be and what features are included, such as multiple backhaul options.
However, it’s the stateless nature of the gateway that’s of particular interest. It doesn’t discern between end nodes (Figure 2). Any node can connect with any gateway, or even multiple gateways. Each gateway will forward the packet to the cloud-based network server and it’s that server that manages the network. It eliminates redundant packets, performs security checks and adapts the data rate for optimum performance. It recognizes the gateway with best return path to the node and uses that gateway for return data.
Figure 2. In a LoRaWAN any node can connect with any gateway, or even multiple gateways.
A key advantage of this stateless gateway structure is that nodes aren’t tied to a specific gateway so there are no hand-offs needed as nodes roam, which is particularly advantageous for asset tracking and pollution monitoring.
Also, as gateways are added to a given geographic area, that gateway becomes part of everyone’s network, regardless of who deployed it. This is unique, and while it may seem odd to have a gateway used by someone else’s customer, the network server and application server, combined with their end-to-end security, make sure there’s no eavesdropping.
In the end, each gateway that gets deployed helps everyone else’s connections, so densification accelerates rapidly. As the node-to-network data rates are so small, in the kilobit range, there is no concern about overloading a gateway’s backhaul. In fact, as more gateways are deployed, the load on each gateway would tend to drop.
For IoT solution providers, the LoRa Alliance is ramping up its marketing and more semiconductor providers are jumping on board to help bring costs down. Now may be a good time to look into using it as the ecosystem is ramping up accordingly.