All the Internet of Things - Episode One: Transports (2024)

Now we’re getting into set-ups where you have to run your own network. Remember, with Ethernet, WiFi, Cellular, and Satellite you’ve got an existing network you’re joining as a client, and with BTLE your phone or computer can act as the network manager.

ZigBee and Z-Wave (as well as ‘similar’ low power radios such as XBees) are often used for home or office-scale networks and automation. These are low power radios, so great for battery usage. But more importantly, they are usable in mesh and high-density point-multipoint or multipoint-multipoint networks - something BTLE does not yet do very well.

These two transports, despite both starting with Z and both used for home/industrial automation, have nothing to do with each other.

ZigBee/802.15.4 is available in both ~900MHz and 2.4GHz. You’ll see it most often as 2.4GHz though, so it shares the same frequencies as WiFi/BT. Zigbee and is a freely available standard with dozens of chips available and a flexible protocols. You can use an existing ‘profile’ like the ZLL (Zigbee Light Link) or just make your own.

Gateways

ZigBee is cheap, cheaper than WiFi, but to connect it to the Internet you’ll need a gateway.

Z-Wave is a more constrained-use protocol, its design for home use and to make equivalent devices you have to buy chips from the single-supplier. It’s a 900 MHz standard so you get a little more range than 2.4GHz ZigBee. especially in an industrial or urban environment since Sub-1GHz penetrates brick and concrete better than 2.4GHz.

The big benefit to going with Z-Wave is you’re joining 100+ other companies that provide cross-compatible support.

The big downside is you are stuck with a very proprietary protocol - even though some parts have been open sourced, you’re still marrying a single company - compare that to the dozen suppliers of ZigBee chips and multiple ZigBee stacks available.

Like ZigBee, you need to have a Z-Wave gateway device to get to the Internet and enable BTLE/WiFi access

ZigBee and Z-Wave do have one thing that they do well that Ethernet/WiFi/Cellular/BTLE do not - that's 'mesh' networking. Mesh, when done right, lets you increase network range with every new device added because each radio acts as a transceiver/router. But, that's when its done well. And it's not easy to do well. In particular, mesh doesn't work nicely with low power networks because every device has to be ready to wake up at any moment and start to do a bunch of packet routing.

That said, BTLE 5.0 will have mesh capabilies, so you may want to compare BTLE 5.0 and ZigBee when designing your low power radio device. In general, BLE is still being improved and developed and is gaining more Z-Wave/ZigBee-like capabilities than the other way around.

• Very low cost and complexity (compared to WiFi, cellular)
• Low power
• 802.15.4 stacks are popular and available from multiple vendors, many even bundle a microcontroller with it
• ZigBee profiles may make your design easy - e.g. ZLL for light control or HA for home automation
• Interoperability: May be able to join existing home area network if on a compatible profile
• Can be mesh-networked (just watch out for power usage)

• Need a gateway for internet access
• Need to manage your own network
• Z-Wave chips are only available from one supplier.
• May have to join an ‘alliance’ or pay into a proprietary network
• DIY authentication, some security built in