Whitespace Wireless for SurveillanceBy Ethan Ace, Published Jan 11, 2012, 07:00pm EST
Needing line of sight for wireless connectivity has always been a major pain for surveillance application Cameras are often needed where there is no direct, clear path from camera to building or headend. To compensate, design complexity and cost often skyrockets.
An emerging alternative may provide a much needed solution to that. TV white space radio technology, using frequency space freed by the shutdown of analog television broadcast, aims to reduce these line of sight issues. In this update, we examine the technology, products available and potential impact.
White space broadband makes use of vacant channels in the VHF/UHF range, between 54 and 806 MHz. Each channel consists of 6 MHz of bandwidth, resulting in the potential to carry 8-15 Mbps of data. These lower frequencies allow for better signal propagation and penetration, making white space superior for non-line of sight applications, currently routinely handled with 900 MHz wireless gear. Like 900 MHz equipment, speeds of white space products, in the range of 4-16 Mbps, will be slower than 802.11 and other higher-frequency radios, due to the smaller channel size used.
Channel Availability and Management
The number and placement of empty channels in each area varies, with rural areas having more free space than urban areas which have more active broadcast television stations. To prevent interference issues, the FCC has appointed a handful of companies (such as Spectrum Bridge and Telcordia [link no longer available]) to maintain a database of frequencies available in each market, and assign frequencies for use in wireless applications, such as surveillance. It remains to be seen how much hassle this will add to wireless deployments.
The wireless radio is then set to use frequencies in one of two ways: (1) Manually, set by the user, or (2) Automatically, based on GPS coordinates checked against the frequency database. The second method allows for changes to take place on the fly if frequencies become available or unavailable at a later date.
Product Availability and Pricing
At the moment, white space radio product availability is very limited. Carlson Wireless is preparing their RuralConnect IP radio, a second generation unit in February 2012. They claim it is capable of about 10+ Mbps of sustained throughput. Achievable distances vary by topology but the vendor believes that it can cover, as an example, a college campus end to end through trees, buildings, etc.
MSRP pricing is estimated at $3,600 USD for the base station and $600 for the client radio when this product ships. These prices are higher than traditional WiFi solutions but not mesh offerings.
We think the product pricing is fairly reasonable for 'hard' traditional wireless installations that would require extra radios and more complex RF engineering and planning.
Impact on Surveillance
In some applications, the lower frequencies and resulting better penetration offered by white space radios will be a distinct advantage:
- Point-to-point links without impacting aesthetics: In municipal surveillance systems or corporate campus settings, users often want to place cameras where line of sight is an issue, do to architectural details or trees, often turning camera placement into a political issue. White space radios, due to their better penetration characteristics may be able to perform well in environments LOS radios would fail, allowing cameras to be placed where they are best located, without removing aesthetic features.
- Point-to-multipoint in broad areas: One surveillance application which frequently goes untouched is surveillance of a wide area where line of sight is unobtainable. Parks are an excellent example of this, as trenching and tree removable are generally out of the question in these environments. White space radio will be better able to handle the obstruction of trees in a broader area, allowing a handful of cameras to be placed around the park.
One way in which white space radios will not compete is speed. Current preliminary product designs claim speeds between 4 and 16 Mbps, a fraction of the 100 Mbps regularly achievable with 2.4 and 5 GHz products. This makes them suitable for use only with a handful of cameras, at most.
We believe white space wireless has huge potential to solve an important and paintful niche segment within wireless. The bulk of the market will likely continue to use products in the 2.4 and 5 GHz ranges, as they are lower cost and able to server many applications. TV white space technology potentially will open up applications these products never could, however, at a cost within reach of much of the market. For those seeking solutions to non-LOS applications, especially in wide space or rural areas, TV white space may very well provide an option where there were none before.
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