What is Longfi?
Learning about LongFi
New network, new protocol
To create a new type of network built by the people, Helium had to come up with a new wireless protocol we call LongFi.
LongFi is a protocol purpose built for a peer-to-peer wireless network that needs to connect thousands of IoT devices to a single Hotspot or enable any device to connect to any compatible Hotspot.
Hotspots use LongFi to wirelessly communicate with:
- Helium-compatible devices/sensors on the network
- other Hotspots to validate legitimate coverage
Examples of network data include location information to track valuable items and prevent theft, environmental data like air quality or temperature, or data from machinery for predictive maintenance.
Compared to Wi-Fi or Bluetooth, what sets LongFi apart is the ability to transfer data bi-directionally over much longer ranges (more than 200x Wi-Fi) and maximize battery life for compatible devices. However, LongFi is not designed for devices with high-bandwidth needs such as smartphones or computers.
Unlike other proprietary protocols, consistent with our open approach we plan to release a LongFi SDK so developers can build applications to run on the network.
The SDK will contain documentation and tools including a C library for LongFi and a complete low power OS designed around the Murata module under open source licensing so developers can rapidly build devices to run on the network. We plan to release the LongFi SDK later this year.
LongFi technical characteristics
We believe our approach of enabling anyone to become a network provider will result in a ubiquitous, secure, and affordable network that just doesn’t exist today.
This network could be built much quicker, and at a fraction the cost of traditional networks.
To be successful the network would need to easily scale to provide broad geographical coverage and support a massive number of devices constantly transferring data without the need for a central authority.
In order to operate, this network needs to support the following capabilities:
- simple way to onboard devices without any third-party.
- the ability for devices to connect to any Hotspot and send data to their destination without a need for central authentication.
- allow devices to directly pay Hotspots to send data.
Existing wireless protocols lack the necessary capabilities to support this new type of network which drove us to build LongFi.
Networks typically require a centralized, trusted entity to authenticate devices before they can be added to the network. For some networks, this requires calling a customer service team to make configurations on the backend before devices can be added to the network.
This simply wasn’t an option for a decentralized network.
LongFi combined with the Helium Blockchain allows a company to onboard as many devices they need without any additional configurations or third-party assistance.
Here’s how it works:
A company is assigned a unique identifier (OUID) which is added to the Helium Blockchain and includes destination information for the data sent from that company’s devices.
One way to think about it, the Helium Blockchain acts as a giant routing table for devices to look up and send data to the desired destination.
The company can onboard one device or thousands and each one receives the same company unique identifier.
These devices are trusted by all Hotspots on the network which brings us to the next capability which is also critical for this type of network: roaming.
The vast majority of IoT networks are private which means each device that accesses the network needs to be authenticated by a central authority.
Just like when you use a cellphone you don’t need to know which cell tower is providing coverage, similarly, we needed a way to ensure devices could connect to any Hotspot with the same experience: devices needed the ability to just “roam” by connecting to any Hotspot and sending data to the proper destination.
So a dog collar could send its location through its owner’s Hotspot or a neighbor’s many blocks away, or precious cargo on a truck could transfer tracking information from a Hotspot in Pennsylvania and then from a Hotspot in New York as it crossed state lines.
With LongFi and the Helium Blockchain, these devices are trusted based on the unique company ID they’ve been assigned with during onboarding. This allows a device to connect and send data via a Hotspot no matter whether the Hotspot is in Anchorage, Alaska or Miami, Florida.
Hotspot owners earn Helium for building the network infrastructure and when devices transfer data over the network through Hotspots.
Hotspots need to be compensated for sending data to the desired location in a way that can be metered so users of the network only pay for the data they transfer. All of this needs to happen without middlemen.
Here’s how it works:
A company’s device sends a packet to a Hotspot. Based on the unique identifier in the blockchain (OUID), the Hotspot knows which company this device belongs to and the destination for the packet.
The Hotspot then sends proof of the received packet to the desired destination (for example, the company’s datacenter), but does not send the full contents of the packet. LongFi accomplishes this “packet preview” through a message authentication code (MAC) included in the packet.
If the company wants the packet it sends payment via Data Credits to the Hotspot, and the Hotspot sends the complete packet (for more info about Data Credits go here). This process is automated and happens in milliseconds.
At the end of the next mining period, the Hotspot owner receives Helium tokens depending on the amount of data the Hotspot transferred compared with other Hotspots that also transferred data during that period.
Every year Hotspot owners earn more Helium for transferring data (for more details about our Helium break down go here).
Without LongFi and MAC capability, companies could receive packet contents for free and Hotspot owners would not receive compensation.
Enhancements over existing wireless protocols
In addition to the unique needs LongFi requires to power a peer-to-peer wireless network, we’ve also had a chance to learn from existing wireless protocols built for IoT devices.
Packet reassembly is designed into LongFi which frees developers from having to worry about transmission sizes.
Other protocols required developers to define a specific packet size based on distances and if a packet size did not fit the parameters based on the distance, then the packet would be lost.
To use an analogy, imagine your Wi-Fi router was on the main floor of your multi-story home and the closer you were to the router the larger the files you could transfer. So on the 3rd floor (furthest away) you could only send a plain text email, on the 2nd floor you could attach a picture to the email, and on the main floor you could replace the picture with a video.
However, if you were on the 3rd floor and you tried to send an email with a video, it would just fail.
The tradeoff is that LongFi packets are larger, but LongFi is designed to be much more developer-friendly by eliminating the need to chop up data to shoehorn into a certain transmission window.
Cryptographic time and location proof
With the combination of LongFi and the Helium Blockchain users of the network can prove time and location for connections on the network.
In other words, each time a device connects there is clear evidence of the time and location of that connection event that is immutable.
This ability to correlate data (e.g., temperature, accelerometer, etc) from a device with cryptographic time and location proof enables a company to prove 100% that the device sent data from a specific location at a specific time.
One way to think about it as a cryptographic notary.
This type of proof doesn’t exist with any other network and opens up a number of new use cases. Here’s a couple examples:
A company drops off a package and the delivery person takes a photo of the delivered package. They send a digest of the photo over LongFi and now they’ve anchored the larger piece of physical data to the network and have positional evidence that they took that picture and that picture existed at that point in time.
Many parties are involved in a supply chain and often there’s no way these parties can completely trust one another’s data. If something is shipped and gets broken during the process with multiple carriers how to identify who’s responsible? With LongFi and the Helium Blockchain, the companies could perform an audit by correlating the packet information with the blockchain and could identify shock event from a sensor at a specific time and place.