By John Maxwell Hobbs
Today, only two to five percent of all doors are protected by a security system, this means that there is great potential for steady growth in the coming years, particularly in light of developments in wireless security technologies. Wireless technology will make it easier and more cost-efficient to install security systems.
There are a number of different wireless standards available for security systems in a network environment. Bluetooth and WiFi (Wireless LAN) are both well know, but ZigBee, an emerging technology shows a great deal of promise in this area. There are a number of proprietary solutions as well, such as Wavenis, and Z-Wave. Each has its own strengths and weaknesses and suitability for specific purposes.
Martin Giebat, Senior Software Engineer Interconnectivity Platforms at ASSA ABLOY says that wireless systems could be suitable for new installations in existing buildings and for extending existing wired systems. "Getting rid of cabling can make installation much cheaper. It's particularly useful in a retrofit, for example, a new installation in an existing building," he says.
WiFi (802.11)
Wi-Fi is a set of standards for wireless local area networks (WLAN) based on the IEEE 802.11 specifications that is primarily used as an Ethernet replacement. It can be used to replace standard LAN connections, such as those between a card reader and a server. It is also good for broadband applications such as video surveillance. Power consumption is fairly high compared to some other standards, making battery life and heat a concern. Wi-Fi networks also have a fairly limited range from between 45 meters indoors to 90 meters outdoors.
The popular 802.11b and 802.11g standards use the 2.4-gigahertz (GHz) radio band, so they can receive interference from devices using the same band such as microwave ovens, cordless telephones, and Bluetooth devices.
The original Wi-Fi encryption standard, WEP (Wired Equivalent Privacy), has been demonstrated to be easily broken, even when properly configured. This led to the development of a new standard, Wi-Fi Protected Access (WPA), which is supported in most current devices.
Bluetooth
Bluetooth was designed as a cable replacement, can be powered by battery for periods of up to a week and is good for connecting devices with peripherals such as wireless headsets. It has relatively high bandwidth and can be used for audio applications and file transmission.
A Bluetooth "master" can communicate with up to seven "slave" devices in a network called a piconet. The specification also allows for the connecting of two or more piconets together in what is called a scatternet, with some devices acting as a bridge by simultaneously playing a master role in one piconet and a slave role in another piconet.
Bluetooth and Wi-Fi both use the same frequency range, but have different purposes. Bluetooth can be used as a low-power, short-range cable replacement for a variety of applications, while Wi-Fi, which covers greater distances at higher bandwidth is intended only for local area network access due to its relatively higher power consumption and more expensive hardware.
ZigBee
ZigBee is a narrowband radio technology that uses the same radio spectrum as WiFi or Bluetooth. Unlike WiFi or Bluetooth, however, a small battery can power a ZigBee network device for long periods, potentially years in a low duty application.
At 250 kbps it is a narrowband technology, which is not usually a problem for security applications. ZigBee allows operations that are difficult or impossible with WiFi or Bluetooth. Devices may sleep in an extremely low-power state for extended periods of time, then wake up to transmit a message only when designated events occur. The "wake up" and message transmission occur very quickly and use tiny amounts of energy. The short wake up time combined with the ability of the device to sleep for long periods gives very low average power consumption.
ZigBee also has the ability to provide a large number of nodes, making it good for large networks such as those in commercial buildings. This makes it possible to deploy thousands of wireless nodes in a commercial building to be used with lighting systems, sensors, windows, and more.
There are still issues related to the way the nodes communicate that have not yet been resolved in the ZigBee specification, so this demands some extra work on the part of the installer.
Proprietary Solutions
While Wi-Fi, Bluetooth and ZigBee are open standards, there are also proprietary solutions available from a number of companies. Wavenis from Coronis and Z-Wave from Zensys are two high-profile examples of proprietary systems.
WAVENIS
Wavenis developed by Coronis Systems, is designed to act as an extension of Bluetooth. The technology makes it possible to extend use of the Bluetooth standard to battery-operated systems requiring a very long, self-supported operating life. It defines the technology in conformance with Bluetooth specifications, but with modifications to make it suitable for Ultra Low Power (ULP) applications.
Wavenis supports a number of different communication modes and supports star, tree and mesh network topologies without using the “master-slave” concept used by Bluetooth. Each device can initiate communication and the wait time between communications can be programmed to occur from between 10 milliseconds to 10 seconds.
Although Wavenis is a proprietary system, it does have the advantage of being an extension of a recognized standard, Bluetooth, and Coronis promotes the system's ability to internetwork with standard Bluetooth piconets.
Z-Wave
Zensys's Z-Wave protocol is primarily intended for residential control systems and supports between five and 232 nodes. The system is designed for ease-of-installation because a typical installation is made and managed by the homeowners themselves. The system is designed to be low cost in order to appeal to the consumer market.
Z-Wave has a throughput of 9600 bits per second. A typical control instruction to switch or dim a light is only a few bytes in length, and so response times are very fast. A typical Z-Wave network contains a mixture of both AC powered and battery powered nodes. Battery power is used for remote controls, sensors, and switches, while AC power is used for devices which require power to operate, such as lamps and power sockets. The AC powered nodes handle routing and the battery-operated nodes will wake up when needed. This scheme allows ULP operation for the self-powered nodes.
Z-Wave uses a mesh network that requires no central controller. The routing protocol allows commands to be routed from one node to another until the command reaches its final destination. This feature is very useful to extend range, and is also used to route commands around sources of interference. Networks can be bridged to extend the number of nodes.
Z-Wave currently has a large installed base, but as with any proprietary system, interoperability with other vendors' products can be an issue.
Summary
Although wireless networks are physically easy to install, there are radio technology issues to deal with such as interference from other devices and blockage from walls.
Giebat predicts that the first wireless security solutions to appear on the market will be fairly simple solutions such as a key fob that communicates wirelessly with a lock, or wireless push button applications such as door openers. "Things like a lock and fob are much simpler because they are just a two node network," says Giebat. "In the short term we can expect to see specific and proprietary applications and compact systems from single vendors," he says.
Interoperability between vendors' products is important in the long term according to Giebat. "An i-building will need a large variety of devices, and therefore needs an open protocol. No single vendor can supply everything," he says. He feels that it will take between three to four years before the market reaches this stage. "It may be necessary in the short term to have proprietary solutions to move the market forward while the standard is being developed," he says.