Caution: Wi-Fi design challenges ahead

Diverse client mix keeps Wi-Fi design strategies 'interesting'

Industry analysis by expert Joanie Wexler, plus links to the day's wireless news headlines

With a kitchen sink full of Wi-Fi client devices showing up in Wi-Fi's 2.4GHz and 5GHz unlicensed bands, enterprises are starting to re-examine their enterprise WLAN infrastructure designs. In addition to perhaps installing more access points (AP) to create additional capacity, consider in your design the broad mix of client devices that might be connecting and their respective behaviors.

They all have variable transmit power levels and receive sensitivity, for example. If you don't have control over your client population -- perhaps your employer is in the hospitality industry, for example, with different guests coming and going -- you might be best off designing your WLAN AP infrastructure for the poorest-performing client apt to darken your doorstep. That would be the client requiring the highest signal strength from an AP in order to connect. The iPad (version 1) and notoriously low-power Vocera badges come to mind as needier clients than most in this respect.

TECH PRIORITIES: How to take your enterprise Wi-Fi network to the next level

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With a kitchen sink full of Wi-Fi client devices showing up in Wi-Fi's 2.4GHz and 5GHz unlicensed bands, enterprises are starting to re-examine their enterprise WLAN infrastructure designs. In addition to perhaps installing more access points (AP) to create additional capacity, consider in your design the broad mix of client devices that might be connecting and their respective behaviors.

They all have variable transmit power levels and receive sensitivity, for example. If you don't have control over your client population -- perhaps your employer is in the hospitality industry, for example, with different guests coming and going -- you might be best off designing your WLAN AP infrastructure for the poorest-performing client apt to darken your doorstep. That would be the client requiring the highest signal strength from an AP in order to connect. The iPad (version 1) and notoriously low-power Vocera badges come to mind as needier clients than most in this respect.

TECH PRIORITIES: How to take your enterprise Wi-Fi network to the next level

Different clients also have different setting requirements that are specific to the various WLAN AP manufacturers, and those must be taken into account, as well.

Similarly, performance can vary if users put devices in their pockets, covering the antenna, and use a headset. The same thing can happen if a device is used in different orientations, such as a tablet computer that toggles between both landscape and portrait modes. "That's because any time you have a mismatch in polarity between the client and AP, which usually transmits vertically, you lose signal," explains GT Hill, director of technical marketing at WLAN supplier Ruckus Wireless.

In short, there's a balancing act to be done to appease some select devices that need an AP to "shout" to them at high power levels when that shouting can cause co-channel interference elsewhere in the network and degrade performance for better-designed clients.

This is an introductory oversimplification of "the client factor" in next-generation WLAN design. Future newsletters will look at these issues more closely and also discuss alternative architectures.

Read more about wireless & mobile in Network World's Wireless & Mobile section.

Joanie Wexler is an independent networking technology writer/editor in Silicon Valley.