WLAN Evolution

WLAN Evolution

Network design focus shifts from coverage to capacity.

Anthropologists say there was no appreciable improvement in the design of stone hand axes for some 60,000 generations — a period sometimes referred to as “the million years of boredom.” However, the emergence of metallurgy enabled new methods of toolmaking, sparked the transition from the Stone Age to the Metal Age, and inspired profound social evolution.

Design is by nature an evolutionary craft, a continual effort to develop more effective solutions to the challenges we encounter. Wireless networking is currently undergoing one of these design evolutions. As Wi-Fi has grown from a “nice-to-have” technology to the essential enabler of the connected enterprise, organizations must rethink their approach to wireless LAN design.

Until recently, Wi-Fi has been deployed with an eye toward coverage of a physical space. Coverage-oriented design focuses on the placement of access points (APs) to provide adequate signal strength and ensure there are no dead spots in the area. The approach was meant to provide service to limited numbers of wireless users, using a limited number of devices and requiring limited bandwidth.

Those limits have vanished.

The proliferation of smarter, more portable devices combined with advanced mobile application platforms have fundamentally altered the requirements for WLAN design. Organizations need to support more wireless users, devices and traffic than ever before — and they must be prepared for continued growth for the foreseeable future. Industry analysts anticipate that wireless data traffic will soon surpass that moving over wired networks.

“Recognizing the critical role that WLAN plays in IT’s mobility and digital initiatives, enterprises are committing to WLAN upgrades and refreshes,” said Nolan Greene, senior research analyst, Network Infrastructure at IDC. “Even as global economic indicators are mixed, IDC believes that enterprises will continue to invest in robust WLAN infrastructure in order to compete effectively in the digital economy.”

More Can Be Less

As wireless demands continue to increase, the focus of Wi-Fi network design is shifting from coverage to capacity. In other words, simply providing basic coverage in a defined service area is no longer sufficient. Organizations need to ensure that the Wi-Fi network supports the current and future capacity and performance levels required of an increasingly mobile workforce.

It might seem like a simple matter of adding more APs — after all, the closer a wireless client is to an AP, the better the data rate. It stands to reason that more APs will increase the raw capacity of the WLAN by closing the distance between clients and APs.

However, it isn’t that simple. Too many APs will actually degrade WLAN performance by creating oversaturation. Wireless clients can become confused trying to access multiple APs with similar signal strength. The effect is similar to when a car radio picks up signals from multiple radio stations broadcasting on similar frequencies.

One way to avoid this issue is with band-steering technologies that reduce traffic on the crowded 2.4GHz band by shifting capable devices to the less-congested 5GHz band. This technique, in combination with directional antennas, high minimum bit rates and low power settings, can provide a good deal of capacity while limiting interference.

High-capacity Wi-Fi planning must also account for variables such as overprovisioning for variations in traffic patterns, optimal use of the wireless spectrum, load balancing, Quality of Service and other factors. This involves careful planning in order to integrate the right number of APs to handle the increased usage without introducing interference.

Professional Planning

A technology-neutral managed network services provider will typically begin the design process by interviewing stakeholders to learn the types and numbers of devices and applications that are being used. This helps in determining the aggregate bandwidth required in the coverage area.

The next step is an onsite survey, which usually involves physically walking around the site and measuring signal strength in various locations in order to build a coverage map. A sweep with a spectrum analyzer will also identify any sources of radiofrequency interference.

Software-driven predictive site surveys now provide an even clearer picture by creating 3-D models of the environment with network simulations and heat maps that give a visual representation of anticipated signal strength and application throughput. A major benefit of predictive modeling is the ability to quickly simulate multiple deployment scenarios and narrow the possibilities to the most-promising alternatives.

Coverage-based WLAN designs were meant to accommodate the occasional wireless user, but they no longer meet modern demands. There are now more mobile devices in the world than there are people, and wireless networks carry more than 100,000 times the traffic they did in 2008. Wireless directly impacts economic growth and productivity, and businesses now rely upon devices and services that didn’t even exist 10 years ago. Evolving design principles focused on capacity requirements can help ensure that organizations aren’t stuck with archaic WLAN performance.


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