Blackout Comms Protocol
Blackout Comms uses a new low-bandwidth secure protocol designed for low bandwidth, high security, and fault-tolerance on low power embedded "edge" devices. This enables off-grid delivery of location data, messages, remote control capabilities, even low resolution image transmission, and other applications that have not yet been realized.
Multi-Medium Compatible
The Blackout Comms protocol sits one level above most other protocols (https, MQTT, LoRa, etc). It is uniquely designed to work with nearly any combination of transmission methods, even simultaneously.
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Working with unreliable transmission methods that offer no inherent security or guarantee of delivery was a high priority in the design of this protocol. Intermittent and unreliable connectivity are expected at all times.
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Every device participating in the protocol is fully capable of sharing responsibility of delivery, validating signatures, preserving security, and rerouting packets on-the-fly, based on more local / fresher knowledge inter-device connectivity and channels most likely to complete delivery, as packets get nearer to the target.
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It is assumed at all times that the communication medium (wire, RF, etc) offers no security, so end-to-end encryption is enforced by every device.
LoRa / ISM Bands
LoRa
LoRa, as you might guess, stands for Long Range. It is a technique for transmitting data over radio frequencies using spread spectrum modulation, invented by Semtech (a hardware company).
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We selected LoRa as the primary means of transmitting data, precisely for those reasons. There is a deep selection of transceivers, antennas, amplifiers, and other products that are options with LoRa.
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ISM Bands
ISM stands for industrial, scientific, medical. It is a frequency range that is often referred to as “unlicensed”, as individual devices and users do not need a license to use the frequency range, provided the equipment they are using meets certain FCC regulations.
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In the US, the ISM bands include 902-928 MHz, as well as the commonly used 2.4 and 5.8 GHz frequencies. In other countries, the frequency ranges can vary.
Frequency Hopping
Regardless of the frequency range being used with LoRa on Blackout Comms, a hopping technique is utilized. This reduces or prevents RF collisions between clusters, as well as individual devices. It also makes each cluster and device less susceptible to jamming, because if a certain frequency is being jammed/spammed, it should only affect an device or cluster for a few seconds.
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The hopping technique uses a secure algorithm whereby every device in the cluster hops to a frequency in unison, which is the “base” frequency for the cluster for a very short amount of time.
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When transmitting directly between two devices, the first packet transmission will happen on this rotating base frequency, while the remaining packets will be striped across different frequencies, specific to the two devices in contact, and only known to the two devices in contact. This per-packet hopping happens very fast, typically within milliseconds.
Blackout Comms Mesh Cloud
Any communicator with WiFi and an internet connection can connect to our mesh cloud. If two or more of your devices are connected to our mesh cloud, an bridge forms between the two devices.
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Bridging using our mesh cloud is a technique that can enable your cluster to span distances of any size. For instance, part of your cluster could be on the US west coast, another part on the east coast, and there will be a single hop connecting them.
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Other devices in your cluster will automatically learn to use this bridge.
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Messages and locations remain end-to-end encrypted as they pass through our mesh cloud.
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Learn more about the Blackout Comms mesh cloud. It requires an inexpensive subscription, but is very easy to set up.
MQTT
MQQT is another popular IoT technology that is often used for low bandwidth communication between devices and sensors. It’s low-overhead, quick, and there’s no guarantee that any given message/packet will arrive at its destination, which may seem like a negative, but it’s a large part what makes MQTT quick, efficient, and perfect for resource / bandwidth constrained devices.
MQTT is a protocol that is implemented by many products, open source, commercial, and cloud-based. It works well with TLS, which can add a level of security, at the cost of adding additional work to the client devices (which, again, may be resource constrained and have very little memory). So, depending on the devices and application, TLS may or may not be desired in a given situation.
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We enable MQTT over 2.4 GHz WiFi as the secondary means of communication, because the characteristics of both the frequency range and protocols are very different from LoRa, so it widens the diversity of the platform significantly, while still preserving the security and decentralized nature of Blackout Comms.
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MQTT is secondary and not at all required for a Blackout Comms cluster or channel. It does open the ability to bridge extremely long distances, since internet, hot spots, satellite, etc can be used.
Other Mediums
Other mediums have been tested but are not currently enabled in the public firmware...
UDP Multicast + 2.4 GHz WiFi
Similar to MQTT (but without servers), UDP is very fast with no guarantee of delivery, and relies on common networking protocols to copy packets/data between devices that are connected to the same network.
UDP works quite well with Blackout Comms, but requires more networking expertise to set up, so for that reason we currently don’t enable that option.
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UART
A wired protocol that you use any time you plug in a USB cable to transfer data. Blackout Comms does still use this if you download analysis data to a PC, but currently its not enabled as a communication method, although it has been in the past (wiring two nodes together with a USB cable).
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CAN
CAN is another wired method Blackout Comms can support, often used in automotive industry. One benefit is the distance that can be spanned with CAN vs other low power wired protocols. This method is currently disabled in Blackout Comms, except for custom deployments.
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BLE
Bluetooth low energy is another option that lends itself well to the way Blackout Comms communicates. We may open this option again in the future, specifically for inter-cluster communication, where two nodes or communicators near one another, but on different clusters, may help to bridge two clusters.