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System Design

Wireless Alarms: Flexible and Functional

Wireless security systems, and especially wireless intruder alarm systems, have been undergoing development for nearly three decades. Despite huge growth in other sectors, the technology remains underused in security and life-safety applications. Today’s solutions are poles apart from those which were on offer many years ago, and as such represent a credible and valuable addition when designing total solutions. Benchmark looks at the case for reconsidering wireless intruder alarm systems.

Wireless technology, in the form of radio-based connectivity, has been used in the security and safety industries since the 1980s, and while improved interoperability with other solutions is somewhat new, many of the benefits associated with wireless were the same back then as they are today. Despite this, the penetration rates for wireless technology in security and life safety systems are still lower than other sectors.

Given the exponential development of wireless solutions in various industries, coupled with the growth within mobile connectivity, communications and even the consumer sector, it is hard to understand why the security sector has been slower to adopt the technology.

Nowhere is this truer than with regard to securing premises against intrusion. Innovations in wireless technologies over the past three decades, coupled with changing demands with regard to risk mitigation, mean that an ever-increasing number of end-users are actively considering the added value that wireless solutions can offer.

The benefits of wireless technology are compelling. Often, wired systems simply cannot be adapted to deliver the kind of protection that a risk assessment demands. An inability to install cabling in a property owing to architectural or design features can lead to inadequate systems being installed, and could leave vulnerabilities for criminals to exploit.

Wireless systems offer a flexible and scalable alternative that – as a standalone or hybrid part-wired solution – can ensure a premises is secured.

Wireless solutions also offer benefits with regard to temporary systems, and can be easily expanded to suit needs during any periods that a site is more vulnerable to crime. Such an approach would often not be practical using wired technology, for reasons of cost as well as convenience.

A commercial concern?

Initially, wireless intruder alarm systems were developed with the residential sector firmly in mind. Many years ago, when security systems were costly, it was quite a hard sell to persuade homeowners to not only pay the cost of such systems, but to also suffer the disruption of the installation process. Few homeowners received insurance discounts or police response at that time, so there wasn’t a great driver to push such an investment forwards.

The wireless system was the solution; cheaper and quicker to install, it was viewed as a domestic option.

Today, wireless technology has advanced to such a stage that the systems are suited to commercial and industrial applications. One of the issues typically associated with wireless systems was a concern about reliability. Many are apprehensive that in commercial applications the shape, size or contents of a site may affect the transmission performance, ultimately leading to potential malfunctions.

Causes could be anything from the positioning of metal filing cabinets, through to warehouse items such as boxes, containers or other objects that could intermittently block a signalling pathway.

Manufacturers have worked with commercial customers, and continued development has been undertaken to ensure that such issues do not translate into real-world failures. A number of solutions have been created which ensure reliability, above and beyond that offered by the one-way radio-based systems that were predominant in the residential sector many years ago.

In commercial and industrial applications, a point-to-point one-way communicating wireless system simply should not be used. With such a system, if a detector or other device fails or loses connection with the control panel, there is no way of knowing what has occurred. The control panel simply will not receive a signal from the device, and as such will not expect a signal until an incident occurs. The presumption is that no signal equates to no incident. On the other hand, a detector might signal an incident, but will be unaware that the message has not arrived at the control panel.

Bi-directional wireless connectivity – sometimes referred to as ‘two-way radio’, but nothing to do with mobile communications devices – is a bare minimum for commercial applications. Another option is to employ a mesh-based intruder alarm system (see the separate panel, ‘Caught in a Mesh?’, in this article for more information). Both solutions offer differing levels of protection against communication loss or failure.

Bi-directional wireless technology introduces a basic safeguard for alarm devices communicating with the control panel. When in use, this approach ensures that the control panel regularly transmits a signal to the detectors to check that the devices are all operational. The detectors then send a confirmation signal back to the control panel.

In effect, the control panel is aware of, and can subsequently signal a fault condition for, any device failures or losses of communication. Equally, if a detector transmits a signal, and does not have that signal confirmed by the control panel, the signal can then be transmitted until it is confirmed as received.

This approach enhances the reliability of the solution. It allows the control panel to alert the user to any issues or faults with the system. If a signal from a detector is missed, many systems can be programmed to then increase the frequency of monitoring for, and reporting, potential problems, until action is taken to check or repair the system.

With a mesh network-based system, all devices communicate with each other as well as the control panel, and the flexibility to reroute signals to avoid unresponsive parts of the system means that the signal will arrive at the control panel. The mesh network monitors itself, as well as the connectivity of the devices, and reconfigures the best transmission paths based upon real-time information.

In summary

Wireless technology today represents a credible, effective and efficient solution that delivers security to commercial and industrial sites, as well as offering other value-added benefits. There is no reason not to explore the options for businesses and organisations; indeed, it could be argued that to not consider this approach could be detrimental to the overall total solution.

Caught in a Mesh

Wireless mesh networks are not new; they have been in use for high risk applications such as military data transfer, critical connectivity and advanced communications for many years. As is typical with technological development, the lifecycle of wireless mesh devices has seen size, power requirements and costs fall, to a point where today the technology can be utilised in intruder alarm systems.

This isn’t to say that it’s simply a case of picking up mesh network technology and dropping it into the alarms sector. If anything, size, power requirements and cost are more sensitive in the security sector than in many higher risk networking environments.

Mesh networking uses what is best described as a multi-path interconnecting topology. Each device is required to process and transmit its own data, as well as acting as a relay point for the transmission of signals from other devices. Effectively, every device on the system is also a part of the transmission path for signals and data.

A mesh network routes its data signals along a variable path between the device which has created the signal and the receiver, in this case the control panel. It does this by effectively ‘hopping’ from device to device until the alarm data arrives at the panel.

Mesh networks are self-healing, in that if a loss of communication occurs, the system can assess the situation, and reroute alarm data. The system polls connections, and will reconfigure data routes around lost paths to ensure that the signal always arrives at the control panel.

Self-healing ensures that the system will operate as specified, even if a wireless link is lost, or if a device which is part of the transmission path fails. For example, if a temporary object that blocks radio-based signals, such as metal racking, is introduced to an area between a control panel and a specific device such as a detector, a traditional wireless alarm system might lose contact with that detector. If an event occurs, the signal will not arrive at the control panel. A self-healing mesh network will realise that the connection between the detector and the panel is lost, and will then send the signal via other devices with which it can communicate, effectively working around the blockage.

Traditional basic wireless systems rely on simple point-to-point communication, where each link is made directly between the control panel and the device. This communication is one-way, meaning that the device cannot tell whether the panel has received the data as signals only flow into the panel.

Even in two-way systems, the panel might be aware that it cannot communicate with a device, but it does not know what the status of the device is. Obviously, in intruder detection alarm systems, this is not acceptable.

By creating a mesh network of interconnecting points, signal integrity is preserved, even in the event of interference or link loss. However, there is another benefit of mesh networking.

Often, sites might have areas, or sub-systems, which simply cannot sustain wireless connectivity with the control panel or main system. This might be due to dense walls, being located in a cellar, or even an area with metal shutters or walls. If there is an accessible path which is not direct, a device can be fitted (even something as low cost as a door contact) to effectively reroute the signals. This removes any ‘line of sight’ issues and delivers greater flexibility when creating a solution.

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