Frequencies and Line of Sight
Another fundamental aspect of wireless technology is the frequency used for transmission. For security applications you want to focus on 2.4GHz, 4.9GHz and 5.1-5.8GHz, which are all license-free (except 4.9GHz, which is dedicated to public safety applications). Given the widespread deployment of license-free systems in urban areas, the 5.1-5.8GHz band is the one that is most commonly used because it has the least amount of interference.
It is important to keep in mind that, regardless of the manufacturer’s statement, any wireless system operating on these frequencies requires clear line of sight. If you don’t have clear line of sight, you will most likely not have a connection reliable enough for your video surveillance needs.
Another important concept to keep in mind is that by using license-free frequencies, you will most likely run into sources of interference. If you think this will keep you up at night, think again. Most high-end wireless systems can handle interference pretty well. Proprietary protocols, self-healing capabilities and built-in spectrum analyzers are tools provided with most high-end wireless systems. If used properly, they can be extremely effective in overcoming high levels of interference.
An in-depth description of how to effectively use those tools in the field goes beyond the scope of this article. However, before deciding on a wireless product, make sure those tools are available in the solution you are considering. Then undertake structured training to learn how to use them effectively in the field. Good tools and a solid deployment action plan will literally save you hours of work.
The importance of thorough training cannot be overstated. Success requires learning as much as possible about this topic, and most introductory courses are free. Even someone with a Ph.D in wireless transmission from MIT should attend at least a couple of training sessions from different sources because theory and practice don’t necessarily match.
3 Steps to a Successful Project
Regardless of the features offered, deploying a wireless system for video surveillance requires three steps: design, bench testing and field deployment.
The design process needs to start from your customer’s expectations and end up with a list of parts to match them. As far as wireless connectivity is concerned, you need to get a map of the site, distance between camera locations, line-of-sight information and bandwidth requirements. Being accurate in the design phase is fundamental for a successful deployment. Enlist the assistance of a wireless technology manufacturer to review and offer feedback for your project design. It will help avoid surprises later on.
Once you come up with a design and have selected your equipment, you can proceed with the configuration. You want to configure the whole network on the bench first, including cameras, encoders, NVRs, and such. Once everything has been configured and tested, you can proceed with the field deployment.
Once in the field, it pays off to be as methodical as possible. Start from the head-end and walk your way out, link by link. Before adding a new link, make sure you can communicate with every camera and every wireless unit you have already installed. A tool such as pinging is very important in this phase of the project.
Once you have deployed the whole network and can ping any device on it, you can start fine tuning the wireless connection and the cameras to guarantee maximum performance. High-end wireless products have embedded tools that measure parameters such as bandwidth consumption and packet error rate and that will guide you in this process. Practice and experience will allow you to reduce your installation time substantially.
An overview of wireless technology would not be complete without taking a look at the future. As touched on throughout this article, the wireless world is undergoing a pretty substantial revolution that is creating a great opportunity for many security integrators.
The introduction of MIMO technology has allowed for greater than 150Mbps of throughput on license-free frequencies - thus expanding the capabilities of wireless. This has also led to an overall decrease in the cost of wireless infrastructure in license-free frequencies, thanks to ‘on-demand’ pricing policies that allow integrators to pay for the system based on the bandwidth needed rather than hardware deployed.
These developments are making wireless networks even more competitive in comparison to wired infrastructure such as fiber and copper. Gains in technology and customer demand are translating into financial gains for integrators that add wireless networks to their portfolio of solutions. Through whatever changes may yet come, once again, knowledge remains the key to success in the wireless arena.
Cosimo Malesci is vice president of Boston-based Fluidmesh Networks, which he co-founded in late 2004.
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