Last week Amazon introduced an entirely new wireless protocol. It’s called Sidewalk, and it’s the solution to a problem that has been around since the beginning of the Internet of Things.
The problem behind the creation of Amazon Sidewalk is one of range. Bluetooth is a short-range radio system, as anyone who has ever walked away from their Bluetooth speaker knows. WiFi sometimes doesn’t work across the house. On the other hand, 4G and 5G connections have a very long range, but they’re surprisingly power-hungry, too much for a simple sensor that waits for a mailbox to open.
The solution to this problem is, and will always be, a new radio protocol. Here, Amazon created a new protocol on the 900 MHz band, the same radio frequencies the first cordless (not cellular) phones used.
Range, Power, Bandwidth: Pick One
Over the last decade or so, there have been several attempts to define a new radio protocol that each face unique challenges.
The ZigBee specification (or IEEE specification 802.15.4) defines a low-power mobile network that is extremely low power, and includes support for mesh-like networking. The bandwidth — the rate at which a device can push data through the network — is exceptionally low, but these aren’t devices that will be sending back video, either. ZigBee is best for wireless sensor networks, like smoke detectors, and it can be found in some ‘smart’ light bulbs.
LoRa is another wireless solution for the Internet of things, and it has an exceptional range of up to 10 kilometers or more in rural areas. A battery will also last forever. But these aspects come at a cost: because of the way LoRa transmits, even a 140-character text message would take a while to get from a device to the wider Internet.
There is a fundamental limit when designing a radio protocol. You can either have bandwidth, long range, or low power, pick any two. It’s possible to transmit a lot of data to the moon, but it’s going to cost a lot of power. It’s possible to build a device that’s low power and can talk to sensors a long way away, but you won’t be able to get a lot of data from those sensors.
This is the problem Amazon is facing with the design of their Sidewalk protocol. They can have long range and low power, but this comes at a cost: it’s not going to transmit much data.
Amazon is getting around these fundamental limitations with bridges. Ring devices already come with support for Sidewalk, and during last week’s presentation, Amazon said they gave some of these base stations to employees in LA, providing coverage for nearly the entire LA basin. If a dog has a Ring Fetch on its collar, you could find it almost anywhere in LA. But this comes at a cost.
Amazon is piggybacking Sidewalk devices on equipment that’s ostensibly not owned by Amazon. This equipment is owned by consumers, who may or may not use Sidewalk devices. Other than the security implications for Sidewalk devices, there is also the consideration that Amazon does not have a right to treat users as ISPs.
Whether or not Sidewalk devices will be used remains to be seen. But Amazon is shipping million of IoT base stations in the form of Alexas and smart doorbells. They might have the network to support a long-range pseudo-mesh network of wearable devices, it’s just a question of if consumers will support other people’s devices.