In the rapidly growing smart home market two protocols, Z-Wave and Zigbee, are emerging from the pack as leading industry standards. Each is supported by its own alliance. The Z-Wave Alliance and the Zigbee Alliance each have more than 3000 members and a similar number of certified products, around 3400.
Both organizations can point to proponents from among the industry heavyweights. For example, ADT, Alarm.com, ASSA ABLOY, Ring, and Silicon Labs back the Z-Wave Alliance and Amazon, Apple, Comcast, Google, and SmartThings (Samsung) support Zigbee. Currently, Zigbee is supported by multiple silicon vendors, while Z-Wave runs on Silicon Labs silicon only.
While both protocols are based on mesh networks, Zigbee has a speed advantage. Zigbee’s 250 kbps (over 4 GHz) outpaces the 100 kbps offered by Z-Wave. However, because smart home controls only use infrequent, low-speed communication, a speed advantage is probably not a factor unless the protocol needs to manage thousands of devices. Zigbee supports 984 feet (300 meters) line-of-sight while Z-Wave covers 100 meters per hop. Practically speaking, either speed will work for smart home applications such as thermostats and refrigerators.
The Introduction of Z-Wave LR
Late last year, the Z-Wave Alliance announced Z-Wave Long Range (Z-Wave LR). This update to the Alliance’s current specification has a longer transmission range and supports up to 4000 network nodes, an increase from the earlier 232.
Z-Wave LR operates on a star network instead of the previous mesh network. A central gateway/hub controls the 4000 nodes using a 12-bit addressing scheme. Z-Wave and Z-Wave LR protocols can coexist on the same network, but all devices on the network must support the new spec for LR to be functional.
The specification has a maximum output power capability of 30 dBm which enables transmission distances of up to several miles. In its phase one, using the Silicon Labs 700 Series platform, the Z-Wave Alliance has demonstrated a successful transmission range of 1 mile (1.6 km) direct line-of-sight with 14 dBm output power. Additionally, by using dynamic power control, the Z-Wave LR extends battery life up to 10 years with one single coin cell.
Z-Wave LR is expected to support new applications outside the smart home. “For almost 20 years, Z-Wave has transformed wireless technology for smart home and security devices. As IoT technology has expanded beyond the walls of the home and to the sidewalk, to commercial buildings, smart cities, and beyond, we decided to support these evolving industry needs,” said Mitch Klein, executive director for the Z-Wave Alliance. “Implementing Z-Wave and Z-Wave LR into IoT networks maximizes value and minimizes costs while providing more breadth of choice.”
What to Expect in the Future?
Even though there are some basic differences between Zigbee and Z-Wave, fundamentally both will work in smart home applications. A designer probably will not fret over the speed or the number of nodes supported by either protocol. Controlling 200 devices within a smart home is more than enough. Zigbee’s 65,000 nodes will never be reached. During everyday application use, it is unlikely a user will be able to detect the difference between 250 kbps and 100 kbps.
The introduction of Z-Wave LR, however, may be a game changer. Z-Wave LR is aiming beyond just smart home applications, attempting to position itself in industrial, commercial smart buildings, and smart city applications. That is a whole new ball game.