Choosing a wireless home automation protocol is a difficult subject to navigate for your average home owner. Each automated door lock or sensor must communicate using a protocol. These protocols may operate over powerline, RF or a combination of both. In this article, we will take a look at some of the common wireless home automation options available to consumers.
ZigBee originated as an ad-hoc networking solution for all types of devices in 1998. ZigBee is a general protocol based on a 2.4Ghz 802.15.4 IEEE physical layer standard for WPANs (Wireless Personal Area Networks). ZigBee is not specific to home automation and is intended to be a low-cost, low-power wireless mesh network standard allowing for secure communication with a data rate of up to 250 kbps and an indoor range of 10 meters. The 10 meter range can also be negatively affected by WiFi and Bluetooth networks sharing bandwidth on the same 2.4 GHz frequency.
The available ZigBee devices are featured on the zigbee.org website. Many different companies provide ZigBee solutions for electrical outlets, light switches and thermostats. One example of a product, is a ZigBee controlled electric outlet made by SafePlug as shown below.
The largest benefit to ZigBee home automation is the rapidly shrinking cost of ZigBee products. With a number of companies rushing to release ZigBee controlled devices, the competition is keeping prices low.
Z-Wave is an ad-hoc wireless protocol developed specifically for Home Automation. The Z-Wave proprietary protocol developed by Zen-Sys in 2002 uses the 900MHz spectrum for longer indoor data ranges than ZigBee’s 2.4Ghz. Z-Wave is similar to ZigBee at a macro-level as both protocols are used for ad-hoc mesh networking. The Z-Wave protocol and the corresponding microcontrollers that use Z-Wave are now owned and distributed by Sigma Designs.
Data rates of Z-Wave vary between 9.6 kbps to 40 kbps and range from 30 meters indoor to 100 meters outdoors. Typically a 900Mhz system can increase propagation range by 2.5 times the amount of a typical 2.4 Ghz system. A single Z-Wave network can support 232 nodes which is typically sufficient for a residential network. Many companies have integrated Z-Wave into their home automation products. One example is a automated door lock by Schlage as shown below.
Z-Wave is a popular choice among home security experts and has been operating in many homes for longer than most ZigBee devices. Z-Wave is also focused on home automation and has customized the protocol to fit that sector unlike the more generalized ZigBee devices.
Insteon was first deployed in 2005 with dual networking of both RF 915Mhz and powerline technologies. Devices on Insteon operate in true mesh fashion and data rates can vary between 2880 bps and 38400 bps depending on whether powerline or RF is used. Insteon is backward compatible with X10 devices, one of the oldest home automation protocols. Insteon can also scale to a much larger size than Z-Wave or ZigBee due to the number of potential nodes and the long distance between powerline. Shown below is a typical installation of Insteon power line and RF technologies.
Choosing a protocol:
All protocols discussed are suitable for home automation. The scale and complexity of a home automation install will narrow down the available options. For example Insteon is easier to deploy in large homes where power lines can act as the main connectivity point. For basic home installations, ZigBee is showing promise in the mobile devices arena with Samsung announcing ZigBee support on their mobile phone devices. ZigBee’s low cost of integration will also be a key factor in it’s deployment into home automation.