Smart homes need wireless connectivity, and Z-wave has emerged as the ultimate solution for home automation. The Z-wave protocol is a wireless, radio frequency protocol designed primarily for smart home networks. All the existing wireless communication protocols had one or the other problem. Bluetooth and Zigbee often shortfall of range while Wi-Fi poses its own limitations in a low-power ecosystem. Interoperability has been another major issue as popular wireless standards have different protocols and implementations for different applications. No one solution could cater to the requirements of an automated home. Z-wave is, now, the solution for all those lingering issues.

Z-wave devices are interoperable and can be easily accessed through the internet or a Z-wave gateway. With a range of around 40 meters, a Z-wave network limited to four hops can connect at most 232 devices. Irrespective of their make or application, all devices can have simultaneous two-way communication over the Z-wave network secured using AES. With sufficient range, optimum data speed, AES security, low-power wireless solution, and interoperable protocol, Z-wave is just perfect for home automation. There are now thousands of Z-wave products in the market, serving as intelligent devices for smart home ecosystems.

What is Z-wave?
Z-wave is a wireless communications protocol developed particularly for smart home networks. It was developed by a Danish company Zensys in 1999. It was introduced to the USA in 2002. With the growing popularity of smart homes, Z-wave is the de-facto wireless solution for home automation applications. At present, there are more than 3000 Z-wave enabled products in the global market, and more than 100 million Z-wave devices operating in smart homes worldwide.

Z-wave uses low-energy radio waves within the 800-900 MHz ISM frequency band and allows data communication between devices at a data rate of 100 Kbits/sec. The wireless network has a range of 40 meters and can use up to 4 nodes for the extension. By allowing data communication over a greater range using low-energy waves at optimum data rates, Z-wave is simply the best solution for home automation devices compared to Wi-Fi or Bluetooth. Almost all sorts of control and sensor applications like lighting control, remote- operated locks, smart switchboards, heating control, garage door openers, etc. can utilize Z-wave for data communication. Z-wave chips are exclusively built by Silicon Labs, and any home automation device can get Z-wave enabled using these chips.

Z-wave plus
Most of the products now available are Z-wave Plus certified. Z-wave Plus or Z-wave 500 is an upgrade of Z-wave technology. It was launched in 2004. It includes enhanced S2 security, more RF channels, better battery life, greater range, and features like OTA upgrading.

Z-wave LR
Z-wave Long Range is the upcoming Z-wave technology. Currently, Z-wave devices connect using a source-routed mesh network topology. The devices can directly communicate within 40 meters range and need a Z-wave gateway to connect to the internet. For devices installed beyond the range, signal repeaters are required. In fact, many Z-wave devices can transmit their own signals. Z-wave LR was announced in September 2020. It will have a 4 times greater range than regular Z-wave signals. At present, a Z-wave network has a maximum range of 100 meters (using up to 4 hops) and supports a maximum of 232 nodes. Z-wave LR will have a maximum of 400 meters range and support up to 2000 nodes.

How Z-wave works
A Z-wave network consists of two types of devices – Controllers/Masters and Slaves. The controller is generally a Z-wave gateway that controls data communication between other nodes and connects them to the internet. The controller comes with a pre-programmed networkID called HomeID. This is a 32-bit ID that identifies a particular Z-wave network. The slaves are included in the network by assignment of HomeID as well as a NodeID. The NodeID is an 8-bit ID that identifies the particular node or the Z-wave device in the network. The process of including a slave device in the network by assigning NodeID and acknowledging the HomeID (specific to a particular Z-wave network) is called ‘inclusion’. When a slave device has to be removed from the network, HomeID and NodeID are deleted from it, and the device is the factory reset.

The Z-wave uses radio signals in range 800-900 MHz. The actual frequency depends on the country where the device is being used. For example, in the USA, Z-wave signals use 908.40, 908.42, and 916 MHz. The same frequencies are used in Canada, Mexico, and Chile. In the UK and Europe, 868.40, 868.42, and 869.45 MHz are used as Z-wave signals. In India, 865.20 MHz is used by Z-wave signals.

The Z-wave devices can communicate with each other only when they have the same HomeID. Two Z-wave slave devices allotted different HomeID belong to different Z-wave networks and cannot communicate with each other. The controller that comes with the particular HomeID pre-programmed maintains a routing table to manage data communication between the included nodes, that is, the Z-wave devices included in its network. The Z-wave uses mesh network topology. Therefore, the devices (slaves) do not necessarily need to connect with the controller to communicate with other devices (slaves) of the network. They can communicate data with each other directly. Even some Z-wave devices transmit their own Z-wave signals. Such devices are plug-in devices and act as repeaters. With such Z-wave devices, a controller can communicate to the devices beyond its original range. Generally, Z-wave devices cannot directly connect to the internet. They connect to the internet only via the controller, which is also a Z-wave gateway to the internet.

Z-wave Alliance
Z-wave actually gained popularity only after 2004. By then, Z-wave Plus was launched, and the home automation industry started looking at Z-wave as the ultimate wireless solution for smart homes. To develop a global standard and promote interoperability among Z-wave devices, a 5-member Z-wave alliance was formed in 2005. The alliance is responsible for developing and maintaining the Z-wave standard and certifying the Z-wave devices. At present, there are more than 650 member companies in the alliance having more than 3000 Z-wave products in the global market.

Z-wave Vs. Wi-Fi
Wi-Fi networks are controlled by a central hub, i.e., a Wi-Fi router. Using Wi-Fi, though it is possible to communicate large data like video streaming and large data files, there are many drawbacks of a Wi-Fi-based network in a smart home scenario. First of all, Wi-Fi uses radio signals that can be exhausting for battery-powered smart devices. On the other hand, Z-wave devices use low-energy signals that even coin battery-powered devices can last for years without battery replacement. As the Wi-Fi network uses a central hub, devices connected to the network cannot directly communicate with each other. They can connect only through the router. In case the router gets faulty, the entire network goes down. That’s not the case with Z-wave networks. The devices can communicate directly and manage data communication even without a controller. They only need to have the same HomeID.

A Wi-Fi network suffers from signal strength and data speed as more devices are connected to the network. In contrast, a Z-wave network is strengthened when more Z-wave devices and repeaters are included. There can be interference and interruption in a Wi-Fi network from nearby Wi-Fi networks. Z-wave networks are free from interference and interruption, as only Z-wave devices having the same HomeID can communicate data with each other. As far as data speed and latency is concerned, Z-wave is designed for sensor and control applications that do not require high data speeds or large data transfers in practice.

Z-wave Vs. Bluetooth
Bluetooth networks have a short-range, and often Bluetooth devices have different implementations for different applications. Z-wave networks have a large range and offer full interoperability between devices of different make and application.

Z-wave Vs. Zigbee
Z-wave and Zigbee are similar in network topology, radio signal range and use the same AES security. Both technologies are designed for smart homes and wireless sensor networks. However, Z-wave and Zigbee have significant differences. Zigbee uses a 2.4 GHz band and is prone to interference and interruption like Wi-Fi and Bluetooth. Zigbee, though offers higher data rates; it has a shorter range than Z-wave networks. Zigbee uses different protocols for different applications and has chips available from multiple vendors. The Z-wave chips are manufactured only by Silicon Labs, and there is only one protocol for all sorts of devices. Zigbee is more suitable for industrial use as it offers higher data rates up to 250 kbps and mesh connectivity up to 65000 nodes/devices. Z-wave with better range and optimum data speed is much useful for home automation.

Conclusion
Z-wave protocol is designed for smart homes, and it fits the best in that segment. Unlike other wireless communication standards designed to cater to a broader application range, the Z-wave standard exclusively meets the requirements for home automation and similar applications. It offers long-range, optimum data rates, mesh network topology, full interoperability, and supports sufficient nodes suitable for a smart home application as a wireless solution.