Home Automation Protocols
In this article we will cover the many different communication protocols used in the Home Automation industry.
BLUETOOTH (Mesh)
Bluetooth is a low-power wireless technology that uses radio waves to transfer data between devices. Most of us know Bluetooth as the method we use to connect audio devices like speakers, head phones or cell phones. All of which use Bluetooth extensively.
Bluetooth Low-Energy technology (BLE) is used by many devices and Hubs in the Home Automation industry. This is a variant of the classic Bluetooth and is targeted at low power devices like the Internet of Things(IoT). It is different from the classic pairing version above in that it does not use pairing technology.
In 2017 Bluetooth Mesh profile was released which added the ability to perform a many-to-many style of communication with provisions for message relay from one device to another. This would create a flexible mesh topology with multiple potential paths between devices (nodes) to ensure delivery of messages. This means that data is relayed by transmitting data over the air (flooding) so that all devices in range can receive the transmission. Each device that then receives the transmission will use the unique sequence ID (included in every message) to determine it it needs to re-transmit (relay) the message Devices keep track of the sequence ID’s and do not relay if they have already seen or relayed the message. Messages also use a time-to-live counter (TTL) that gets decremented by one every time it gets relayed. The TTL is typically set to 3 and as it hops and reaches a value of 1 the device will no longer relay the message.
Bluetooth BLE is intended for devices that only need to transmit small amounts of data periodically, which can extend battery life by months or even years.
Thread
It is a low-power wireless mesh networking protocol based on the universally supported Internet Protocol (IP), and built using open and proven standards. A Thread network can self-heal meaning that if one of the devices in the network becomes inoperable the network can adjust and continue to operate. Thread is interoperable by design.
Devices in a Thread network are authenticated and communications are encrypted. Devices also use very little power and can operate on battery power for years.
A thread network will consist of Router and End Devices. A Router is a node that forwards packets for other devices and provides services for devices trying to join the network. A End Device is a node that communicates primarily with a single Router and does not forward packets for other network devices. It can also disable its transceiver to reduce power consumption. The relationship between a Thread Router and End Device is that of a Parent-child. A End Device will attach to only a single router. The Router is always the Parent while the End Device the child as a child.
Wi-Fi
Wi-Fi is wireless networking technology that uses radio waves to exchange data between a wireless router and Wi-Fi enable devices throughout your home. You may think that Wi-Fi is an acronym for something but it’s not. Wi-Fi is actually a brand name created by a marketing firm.
The IEEE 802.11 standard is what defines the protocols that allow communications between Wi-Fi enabled devices. There are multiple versions of this standard which include 802.11n (Wi-Fi 4), 802.11ac (Wi-Fi 5) and 802.11ax (Wi-Fi 6). There is even an extension to W-Fi 6 named Wi-Fi 6E that allows communication over a new frequency at 6GHz.
| IEEE Standard | Created | Maximum Speed | Frequency Band |
|---|---|---|---|
| Wi‑Fi 6E (802.11ax) | 2020 | 600 to 9608 Mbit/s | 6 GHz |
| Wi‑Fi 6 (802.11ax) | 2019 | 600 to 9608 Mbit/s | 2.4/5 GHz |
| Wi‑Fi 5 (802.11ac) | 2014 | 433 to 6933 Mbit/s | 5 GHz |
| Wi‑Fi 4 (802.11n) | 2008 | 72 to 600 Mbit/s | 2.4/5 GHz |
| (Wi-Fi 3)802.11g | 2003 | 6 to 54 Mbit/s | 2.4 GHz |
| (Wi-Fi 2) 802.11a | 1999 | 6 to 54 Mbit/s | 5 GHz |
| (Wi-Fi 1)802.11b | 1999 | 1 to 11 Mbit/s | 2.4 GHz |
| (Wi-Fi 0)802.11 | 1997 | 1 to 2 Mbit/s | 2.4 GHz |
Wi-Fi is the most recognized of the protocols/standards because it used by so many products and devices purchased by the general public. Almost every home has a W-Fi router installed which makes connecting Wi-Fi based Home Automation device a snap. In fact, Internet of Things (IoT) devices that utilize this protocol require no additional hardware or equipment. They basically just work out of the box.
Wi-Fi routers will typically use two different radio frequencies 2.4GHz and 5 GHz to communicate with Wi-Fi devices throughout your home. The 2.4GHz frequency has been around from the early days and is shared with many devices like cordless phones, microwaves, baby monitors, audio devices and more common devices used in a home. If you have a lot of these devices in your home you could experience overcrowded channels which will result in interference with your home automation devices. While many older home automation devices would work only on the 2.4Ghz frequency band newer devices will work on both 2.4 and 5 GHz.
While the 5 GHz band provides for faster data transfer speeds it has more trouble going through walls and obstacles in your home. This results in a shorter range (distance) which may cause intermittent disconnects of your devices if they are place too far from your router.
Zigbee
Zigbee is wireless mesh network protocol that targets battery-powered devices in a home automation system. It is based on the IEEE’s 802.15.4 network standard. Zigbee has been used in the home automation industry for more than a decade for low-powered devices that don’t require a lot of bandwidth – like your smart home sensors.
A mesh network is a local network topology in which the nodes (devices, bridges, etc.) communicate with other nodes to efficiently route data to clients. There is no dependency on any specific node which allows very node to participate in the relay of data. This means that each wireless node can communicate with each other and share data across a large area. Zigbee’s ability to utilize mesh networking means it can increase transmission range and provide greater reliability using self-healing algorithms.
For example, in a Zigbee based network you could have a master coordinator node that controls other network nodes. If one node fails for any reason and can no longer communicate with a second node, the master node and second node may re-establish communications by linking to a third node that is within range. In a mesh network every node acts as a repeater of sorts, and all nodes cooperate in the distribution of data – hence mesh network.
Zigbee operates in the 2.4GHz band and can support up to 65,000 nodes on a single network.
Z-Wave
Z-Wave is a wireless communication protocol used mostly in home automation systems to allow devices to communicate with each other. It is also based on mesh technology allowing each device to act as a repeater to provide a self-healing reliable network.
There are 1000’s of home automation products that utilize the Z-Wave protocol which allows for integration between many different manufacturers products. Z-Wave has one of the broadest product selections available.
Z-Wave uses a source-routed mesh network architecture. In this type of network devices send data/messages (initiator) which are then relayed by neighboring devices. Devices can communicate to each other by using other nodes to dynamically route around and circumvent obstacles or radio dead spots that might occur in a typical home. For example, data/messages from node A to node C can be successfully delivered even if the two nodes are not within range by using a third node B which can communicate with bot nodes A and C. If the preferred route is unavailable, the message originator will attempt other routes until a path is found to the C node. This means that a Z-Wave network can reach much farther than the radio range of a single node.
Z-Wave operates at 868.42 MHz in Europe, at 908.42 MHz in North America which avoids interference with systems that operate on the crowded 2.4GHz band. To provide security Z-Wave uses AES-128 encryption.
IP Protocol Over Ethernet
Ethernet is a wired networking technology used in Local Area Networks (LAN) and Wide Area Networks (WAN). It is also considered one of the key technologies that make up the Internet. Data is transferred over a physical cable as apposed to Wi-Fi that uses wireless technologies to send over the air. When it comes to Ethernet vs Wi-Fi speed, Ethernet is almost always lower latency (less delay), and higher bandwidth (more capacity) than Wi-Fi.
Cables for a Ethernet network are almost always classified as Cat 5e, Cat 6e or similar. The Cat stands for Category. The number that follows refers to the specification version supported by the cable. Generally a higher number means higher frequencies and therefore faster speeds.
| Category | Shielding | Max Transmission Speeds | Max Bandwidth |
|---|---|---|---|
| Cat 5 | Unshielded | 10-100Mbps | 100MHz |
| Cat 5e | Unshielded | 1,000Mbps to 1Gbps | 100MHz |
| Cat 6 | Shielded or unshielded | 10Gbps up to 55 meters | 250MHz |
| Cat 6a | Shielded | 10Gbps up to 55 meters | 500MHz |
| Cat 7 | Shielded | 100Gbps up to 15 meters | 600MHz |
| Cat 7a | Shielded | 100Gbps up to 15 meters | 1,000MHz |
| Cat 8 | Shielded | 40Gbps up to 30 meters | 2,000MHz |
Note: Maximum distance of an ethernet cable is 100 Meters or 328 Feet
There are many Home automation devices that use the Ethernet (TCP/UDP/IP protocol) over Ethernet. Some examples are IP Cameras, Hubs, Bridges, Televisions, Media devices and many more.
A Ethernet network can also supply power to devices using using Power Over Ethernet (POE) . This is accomplished by sending power over a pair of wires in the Ethernet cable from the POE enabled router. This can eliminate additional cabling thereby reducing overall time and costs.
Comparison
| Specification | Ethernet | Wi-Fi | Zigbee | Z-Wave | Bluetooth | Thread |
|---|---|---|---|---|---|---|
| Technology | Physical Wire | Radio Frequency | Radio Frequency | Radio Frequency | Radio Frequency | Radio Frequency |
| IP Based | Yes | Yes | No | No | No | YesIPv6 |
| Frequency | N/A | 2.4GHz & 5GHz | 915 MHz or 2.4GHz | EU 868MHzUS 908MHzAU 921MHz | 2.4GHz | 2.4GHz |
| Mesh Capable | N/A | No* | Yes | Yes | Yes | Yes |
| Mesh Hops | N/A | N/A | Unlimited | 4 | Unlimited(TTL based) | Multiple |
| Max Devices | 253** | 250 | 65k | 232 | 32,767 | 250 |
| Battery Power Consumption | N/A | High | Very Low | Very Low | Very Low | Very Low |
| Max. Range (indoor theoretical) | 100m 328' | 45m 150' | 10m35' | 30m100' | 100m 330' | 100m 330' |
| Theoretical Max Speed | 10,000 Mbps | 700 Mbps | 250kbps | 9.6-100 kbps | 2 Mbit/s | 250 kbps |
| IEEE Standard | IEEE 802.3 | 802.11a/b/g/n/ac/ax | 802.15.4 | 802.15.4 | 802.15.1 | 802.15.4 |
*Devices do not support Mesh (do not communicate with each other). Wi-fi can support Mesh networks
**Based on a typical home network. Actual number will depend on network configuration.
Author: Phil Ciraolo
I have been in the security industry for over 44 years. During this time I held many positions including installer, service technician and design engineering. Systems worked with include intrusion systems, video surveillance, card access, intercoms and many others. Installations ranged from small residential to large integrated systems. I have walked across overhead cranes, crawled in under floor dirt crawl spaces, hung from 50 foot bucket truck in -10 degree temperatures all with the sole purpose to install security systems. To help with todays App crazy world I also have formal training in software programming and app development. I hope that with my experience I will be able to help you with anything security and home automation related.
