Site surveys are still needed

Site surveys are still a useful tool for risk management in enterprise wireless LAN deployments where business-critical applications such as wireless VoIP require carefully planned coverage and capacity.

Site surveys are still a useful tool for risk management in enterprise wireless LAN deployments where business-critical applications such as wireless VoIP require carefully planned coverage and capacity. In the past, site surveys were used to determine where to deploy access points to provide the required coverage and capacity with the fewest number of access points. Site surveys determined access points’ transmit power and channel settings to minimize interference with other access points. But two recent developments – intelligent access points and low-cost thin access points – have altered the goals for site surveys in enterprise WLANs.

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Intelligent access points can now monitor their coverage area and automatically optimize their transmit power and channel settings, a welcome improvement over site surveys. Thin access points have reduced the coverage and capacity cost. Instead of using site surveys to optimize the location and number of access points, thin access points now can be deployed in convenient and easily accessible locations that are less than optimal for coverage, but because the thin access points cost less, additional access points can be deployed to compensate.

However, these developments don’t make site surveys obsolete. Until there is an access point on every desk, at every cubicle and in every room to provide complete coverage and capacity requirements, site surveys are still a valuable tool, especially in enterprise WLAN environments.

Today, “an access point everywhere and anywhere” is not a realistic WLAN deployment option. Access points can use existing Ethernet connections, but it is unlikely that there will be enough of these connections to deploy access points everywhere and anywhere. If there are not enough existing Ethernet connections available, new Ethernet connections will be required, which can be expensive and disruptive to install. And the cost of purchasing an access point is not limited to its price. Thin access points might be less expensive than thick access points, but they do not include the price of the required wireless switch or appliance and any access point license fees. For these reasons, decisions will need to be made on where and where not to deploy access points, increasing the risk that the coverage or capacity will be inadequate.

How significant is this risk? That depends on how critical the coverage and capacity is for your WLAN applications. In an office environment, inadequate coverage or capacity might result in a simple help desk request that can be corrected by deploying an additional access point. However, in a hospital, this might result in the inability to contact a nurse or doctor on a wireless VoIP telephone during an emergency.

Site surveys can assist in managing this risk by confirming that the WLAN provides the required coverage and capacity. As more organizations embrace WLAN applications such as VoIP, the need to manage this risk becomes increasingly important.

Hong is WLAN product manager at Foundry Networks. He can be reached at mhong@foundrynet.com.