Video: Wireless 101

Here's your primer on wireless communications


Video surveillance is a big money-maker for many integrators and that will trend will continue, as analog system saturation gives way to IP. And given the physical limitations of digging and trenching in many areas, fixed wireless broadband is often times the technology of choice for communications.

“Fixed wireless broadband is compelling versus trenching a parking lot or paying a recurring monthly bill to a cellular provider,” said Scott Imhoff, director of business development at Cambium Networks, Rolling Meadows, Ill. Fixed wireless broadband typically operates at 5 GHz, re-creating the Ethernet computer port.

“Think of it as a wireless Ethernet cable,” Imhoff explained. “Rather than burying cable, you have an RJ-45 jack that plugs to the camera or security sensor. The signal is beamed to an access point.”

An access point is a fixed, central location where all traffic from various sensors or cameras around a customer’s premises comes into.

“Any skilled wire technician will be able to install fixed wireless,” Imhoff continued. “The big difference is knowing how to waterproof outdoor connections. But it’s the same wire strippers, the same RJ-45s, the same surge suppression for lightening strikes.”

College campuses, enterprises and the military all use these systems, said Ian Torok, director of Technical Services at BearCom, based in Garland, Texas. Most often they are used to integrate connections within the campus or create connections from point to point.

Torok cites Dallas as a prime example. The city has a wireless 150-camera system that collects data into a funnel that is backhauled with OFDM (orthogonal frequency-division multiplexing) point-to-point systems to the main server, managed by the Dallas internal IT department. BearCom maintains the radio connection and the city maintains the IP connection.

 

Know your 802.11n

A security dealer getting started in wireless must know the 802.11 standard, especially 802.11n. With 802.11n there’s the whole package: speed, resiliency and quality of service. Today, 802.11n is pushing 450 to 600 MB speeds. Experts say that, in a few years, 802.11 will reach Gigabit speeds.

“A security dealer should lay out what they want to accomplish: How much bandwidth is needed? How big is the network? How much data is there?” Torok said. Product is deployed based on those computations.

What about Wi-Fi as opposed to 802.11n? Wi-Fi is best-effort Internet access and is great for reading email at Starbucks. Security dealers do not want it for fail-safe applications. The 802.11n communications is a more robust protocol that allows high-speed transmission at longer distances and can trade speed for distance or vice versa.

“Before implementing a wireless system, a link analysis should be done on the proposed locations and path to determine the probability of success of the connection,” Torok said. The analysis determines where dishes need to be placed. A wireless provider can manage the analysis.

The 802.11n protocol also gives integrators speed without requiring more spectrum. It uses spatial multiplexing (SM) to split data into pieces. It then sends each data piece on parallel “spatial” channels—much faster than it would take to send that same data serially. Without SM, 802.11n can achieve 150 Mbps. With SM, it can hit 300 or 450 Mbps if both the transmitter and receiver have at least two and three antennas (and RF chains), respectively.

 

Terminology and nomenclature

In telecommunications, a point-to-point connection refers to a wireless connection between two antennae that beam signals to one another, Torok explained. “Wireless systems have a low probability of being intercepted, as it is nearly impossible to decrypt a point-to-point system,” he said.

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