IT Managers Ignore Wireless at Their Peril
Wireless communication, once the domain of broadcasters and carriers, is now available everywhere we work, play, study, dine and drink coffee. These days wireless also seems to be equipped in every imaginable device, including toys made by the likes of Fisher Price. The technology can also be thanked for eliminating what was once the common eyesore of Ethernet cable carpets.
Wireless has become an ubiquitous service, not just one of convenience. On a typical morning commute, more often than not, a myriad of blinking mobile Internet dongles and illuminated iPhones glow aboard buses and trains as workers link in to the office, or digest their morning news.
New breeds of business have emerged, comprised of roaming staff that connect to headquarters via wireless, while others use the technology to free employees from the shackles of their individual cubicles. It has made the Web more convenient and accessible, and created new expectations where websites can only be the best if they cater to handheld device screens.
The technology has moved from public obscurity to a place in front-line politics, with major political parties planning to roll out the technology across hundreds of thousands of kilometres to bring regional Australia into the 21st Century. Within enterprises, the wireless network allows staff to replace desktops for laptops, use their smartphones for work, and provide secure and separate Internet access for visitors. Wireless is a CapEx goldmine for offices with fewer than 100 staff, too, because it offers a means to provide voice and data access without the need to punch holes through walls to lay down Ethernet cables. But there are limits, for while the upfront installation costs are much less than wired connectivity, the decision must be balanced against the technology's slower speeds and higher latency.
IEEE 802.11 is a set of WLAN standards that span the 2.4, 3.6 and 5GHz frequencies, governed by the Institute of Electrical and Electronics Engineers (IEEE). The first amendment in 1999, dubbed 802.11a (or simply .11a) incorporated orthogonal frequency division multiplexing technology to boost network speeds in the 5GHz band to between six and 54 megabits per second (Mbps). 802.11b followed months later with a new set of spectrum technologies that would be surpassed within four years by .11g after multiplexing technology produced .11a speeds for the popular 2.4GHz band.
While continually improving, most speed ratings for networking devices are over-inflated, and indicate the theoretical maximum data rate, rather than the throughput users receive. Good cabling, architecture and avoidance of radio interference help improve speeds. The most recent amendment, .11n, was ratified in September 2009, although vendors had sold the technology for years beforehand under the "draft" and "draft 2" disclosures. The much-anticipated technology defined the use of high throughput radios that can support theoretical raw network speeds rates as high as 600Mbps. The amendment builds on a string of forerunner standards with the inclusion multiple-input multiple-output (MIMO) antennae and 40MHz channels to the physical layer, and frame aggregation to the Media Access Control (MAC) layer. Like .11a, the newer standard offers businesses the ability to use the 5GHz band, which in most cases has far less interference than the 2.4GHz band that competes with Bluetooth and microwaves. Both bands are accessible under the dual-mode .11n standard. Turn off the 2.4Ghz spectrum, however, and your new iPhone 4 (as well as most portable devices) will not connect.
The .11n standard brings more speed, throughput and uses cleaner spectrum bands, but also introduces new challenges to deployments in existing wired networks, AirSpy Training founder, David Coleman, notes in a research paper.
"Using standard Power over Ethernet (PoE) to remotely power access points may no longer be possible [with .11n]," the paper reads.
WLAN manufacturers have since built in support for Power over Ethernet while delivering .11n wireless, but Coleman warns other problems remain with the standard. "The increased bandwidth from multiple 802.11n access points might also create backhaul bottlenecks anywhere from the access layer to the core layer of the wired network infrastructure."
He notes in the research that there may be design challenges with running .11n alongside a/b/g transmissions and points to new security considerations that may have to be addressed with intrusion detection systems. Coleman says .11n is also immune to data corruption from the radio frequency phenomenon known as 'multipath', which corrupts data travelling over earlier 802.11 standards, and causes TV broadcast images to become offset and fuzzy. The next standard in line, amendment .11u, is a plan to standardise user access based on a relationship with another external network, meaning agreements could be forged between wireless hotspots, or access could be restricted to limited services between an agent and device. American telco consultant, Bill St Arnaud, wrote that the standard will "improve the experience of a travelling user who turns on a laptop in a hotel many miles from home. Instead of being presented with a long list of largely meaningless Service Set Identifier (network names), the user could be presented with a list of networks, the services they provide, and the conditions under which the user could access them."
Standard amendments .11k and .11r improved transitions of networked devices over wireless networks. The former defined a new way to distribute traffic to access points (APs) that overthrew the former process whereby each device jostled for the closet AP with the strongest signal. That process fell over when too many devices flooded the AP and left others underutilised, degrading network performance. The .11k amendment would flick extra devices to empty APs, regardless of whether the signal was weaker, meaning better throughput in the end. The latter standard, .11r, sped up device swapping that occurs between APs as a device travels through a WLAN. The swapping process became complex and slow after the introduction of IEEE amendments such as Wi-Fi protected access and .11x, and the rising popularity of smartphones.
Access points (APs) are often the most expensive part of WLAN deployments. The devices boost network capacity and coverage, but additional redundant APs can add expense and increase management requirements. Thin APs relay network management to centralised controllers, and peaked in popularity over WLANs built on the earlier 802.11 wireless standards. The essentially dumb terminals are particularly attractive for large-scale deployments that require hundreds or thousands of the devices because they cut down on the cost of monitoring and upgrading fat APs, which carry packets between wireless and wired networks and are self-contained and fully-functional.