You probably don’t think about it, but most police cars have a big repository of digital data.
There are laptops full of officers’; reports, digital video cameras with recorded evidence, GPS with location data as well as the usual vehicle telematic information. At the end of a shift, someone has to plug an Ethernet cable into the equipment and download it all, and also pull out the writeable DVD disk that records the video.
The latest in Wi-Fi technology, 802.11n, is changing change that. Thanks to its improved throughput over previous versions, a Canadian wireless LAN integrator — who asked not to be identified — is creating a system that lets a squad car data download wirelessly and automatically when the vehicle parks outside a police station. <p.
Speed thrills, so to speak, and 802.11n does that in spades. It roughly boosts usable throughput from the 25 to 30 Megabits per second of the previous versions to 200 Mbps, giving the ability for organizations to add all sorts of new wireless services — such as voice, video surveillance, barcode and security access — to run over what had been seen as a data-only network.
It does that by running on the 5.8 GHz bands, where there’s less interference compared to the 2.4 GHz bands 802.11 b and g access points are limited to, by using MIMO (multiple input multiple output) technology, which uses several antennas to broaden the coverage area and by being able to bond two 20 MHz channels together to hike throughput.
Some looking at installing a new ‘n’ network believe it can be accomplished with some vendor-supplied site survey software. All of this may be true in a small office, but for anything bigger, an RF expert should be consulted. More importantly, the network has to be designed around the organization’s needs.
“The primary thing they need to do is understand what they’re looking to do with wireless,” says Tim Zimmerman, a Gartner principal research analyst who specializes in wired and wireless networking.
“That involves understanding the capacity that’s needed for the applications they’re going to look for today as well as tomorrow.” Increasingly more applications are coming out that will push a wireless network, he said. But a/b/g networks were designed for data and not rich media, and for connectivity not capacity. That’s not good enough today.
Tyler Cashion, founder and chief operating officer of Enduria Wireless Solutions, an Ottawa integrator that specializes in WLAN, cautions planners that 802.11n inevitably results in “applications creep,” where users add more devices to the wireless network as they realize the throughput it can handle.
After determining needs, a detailed site survey to locate the APs is essential. It’s still more of an art than a science.
“The placement and the quantity of access points is often a challenge,” says Roger Sands, worldwide business manager for mobility products at Hewlett-Packard Co. “There’s either too many or too few, depending on the business applications they’re intending to run. “You can do planning and modeling or you can perform a walk-around type of survey, but in either case there’s usually some adjustments that have to take place post-installation.
The reason for that is there’s so many dynamic things in an enterprise in terms of building materials, the dynamic nature of the offices.” So don’t do site surveys in empty buildings. Not only can people can change radiation patterns, so can desks, mirrors, metal filing cabinets, metal doors, and, in warehouses, inventory such as metal cans or bottles of fluids.
Putting up too many APs can create co-channel interference, while putting up too few on the assumption that 802.11n’s coverage area is broader than a/b/g’s will only mean users at the edge will connect at fairly low data rates. So there’s no getting away from the traditional overlapping coverage model.
Configuring the WLAN is another issue.
While 802.11n APs are is backward-compatible with a/b/g devices, only ‘n’ devices can take advantage of the throughput of the 5.8Ghz band. Organizations that have staff or guests with older laptops or wireless modems should consider buying dual mode APs so those devices use 2.4Ghz channels, experts say, while the newer devices only get on the 5.8Ghz channels. The price of a mixed network, however, can be lower throughput unless the design is done carefully.
On the other hand, 802.11n’s security includes WPA2, which is better than earlier Wi-Fi security protocols. That’s one reason organization should consider implementing only an ‘n’ network to shut out less secure devices.
Because 802.11n uses more power than earlier versions, the wired network will have to be upgraded to Gigabit Ethernet. Check the Power over Ethernet requirements of the APs you’re considering, advises HP’s Sands. Most 802.11n access points use Gigabit PoE to support the increased throughput. However, Sands warns that the PoE requirements of some AP’s are higher than the 802.3af standard.
Roland Aucoin, product manager for advanced technologies at Connex See Service Inc., a Richmond Hill, Ont., systems integrator with six offices across the country, pointed out that AP manufacturers try to differentiate themselves through additional features: companies may include small scale firewall capabilities in some access points, while others specialize arrays for saturating a lecture hall.
There is a side benefit to such capabilities, points out Ron Groulx, a product manager with Fluke Canada, a maker of Wi-Fi analyzer tools: They can vastly affect wireless network speeds from manufacturer to manufacturer.
Finally, there’s voice over Wi-Fi, which Michael Rozender, a Grimsby, Ont.,-based broadband consultant who has worked on several 802.11n projects says “is getting hotter than hot.” Wi-Fi wasn’t designed for voice, he says, so the WLAN has to be tailored for it. However, an increasing number of smartphones – including, most recently, BlackBerrys running Mobile Voice System 5 – mean an increasing number of organizations want it.
“802.11n is a game changer,” says Rozender. But only if it’s done right.
