Wireless LANs are sprouting up in corporations large and small. While companies understand the possible benefits from these systems, IT departments often struggle with one vexing issue: where to place WiFi access points. Firms like AirMagnet, AirWave, Aruba Wireless, AutoCell Laboratories, Cisco, Cognio, Trapeze Networks, Wavelink, and Wireless Valley Communications are trying to make it easier for companies to deal with potential pitfalls, such as dead spots or insufficient bandwidth.
These vendors’ products are designed to help address the unique challenges found with wireless LANs. Deploying a wireless LAN is much more difficult than setting up a wired LAN because users have to address a wide range of bandwidth contention and interference issues. Transmission rates can vary because of the thickness of cubicle walls, the placement of microwave ovens, the power of the WiFi antenna, and overlap from neighboring networks.
The last item has become more and more problematic. “In office buildings, it has become quite common for wireless LANs to overlap and create throughput and channel contention issues,” noted Greg Collins, senior director at market research firm Dell’Oro Group.
Network Design
Because interference issues tend to be site specific, many companies spend a lot of time and put a lot of effort in the network design stage of their deployment where they try to figure out where to station these devices. “Often, companies rely on network systems integrators who conduct site surveys to determine how many access points need to be installed and where to position them for maximum bandwidth utilization,” noted Abner Germanow, program manager at market research firm International Data Corp.
As part of the survey, a firm often has to ascertain which applications the network will support, how much bandwidth the applications require, and how many users will use the wireless connections. There are a few general guidelines for wireless LAN deployments. “An access point is able to handle traffic from about a dozen users,” Dell’Oro Group’s Collins told TechNewsWorld.
Because it’s hard to anticipate when walls, windows, or other objects will interfere with wireless communication, often an individual armed with a blueprint of the facility and strong legs walks around the building, installs access points in different spots, and then tests how well they perform. When working with a room or two with a few access points, this may require a day’s work, but in companies with thousands of users spread across tens, or even hundreds, of distributed sites, the process requires a substantial investment in manual labor.
Once a network is running, additional surveys are required. “As users become more familiar with WiFi capabilities, network usage and traffic flow change, sometimes quite dramatically,” noted Craig Mathias, principal at market research firm Farpoint Group. As a result, problems can arise in high-traffic zones where throngs of users might suddenly appear, such as a popular conference room.
In response, vendors have been working on a few fronts to improve network performance and reduce the manual labor requirements associated with site surveys. Component vendors have been improving access point’s range, throughput, and ability to automatically adjust to adverse network conditions and avoid interference.
Automating the Grunt Work
In addition, suppliers have been working to take the time, drudgery, and cost out of manual site surveys by automating the process. New tools enable companies to import a location’s floor plan and use a simulator to electronically configure a site. These applications try to account for concrete walls, dry-wall, and windows — whatever is present in the environment — and demonstrate how access points will perform in different scenarios. Users can drag and drop access point to various locations and see a new design’s impact on coverage and signal strength.
Also, suppliers have been developing software control systems that are embedded in access points, clients, and chips, so 802.11 networks can basically manage themselves. These tools first verify that equipment is working properly and then collect performance data, such as throughput and response time. These systems self-adjust, for instance an access point would switch to another channel or power down in the face of a crowded channel. The systems also note differences between planned and actual performance metrics and recommend actions, such as adding/removing access points or changing configurations, that should remediate performance problems.
The best way to use these tools is debatable. Vendors have been pushing users to take advantage of them in the beginning of the deployment process. “The effectiveness of the WiFi configuration tools is unclear because network performance is such a site specific process,” Farpoint Group’s Mathias told TechNewsWorld. “The only way to truly understand what is happening on the network is to deploy it.”
Pay Me Now or Pay Me Later
Rather than focus on deployment issues upfront, Farpoint Group’s Mathias recommends that companies oversaturate their initial network and then conduct performance tests once it has been running for a while. “Wireless LAN technology has become so inexpensive that it doesn’t make economic sense to spend lots of money on a site survey when access points only cost a few hundred dollars,” he noted.
Other observers think the tools are needed in the design phase. “Increasingly, companies are running VoIP over their wireless LANs so mobile workers transmit voice as well as data transmissions,” IDC’s Germanow told TechNewsWorld. “Because these applications are sensitive to transmission disruptions, corporations need to be sure that they have sufficient bandwidth to support them.”
Whether it is in the design phase or after implementation, the need for these tools is expected to increase because wireless LAN usage is rising and gauging performing is becoming more complex.
Loading ...
