Nortel Networks NN43001-504 manual Assessment through a Wlan site survey

48Planning

Assessment through a WLAN site survey

Technical support for VoWLAN is contingent on customers performing a site survey of the WLAN. Currently, Nortel recommends the use of the Ekahau Site Survey tool to verify the network deployment, although other site survey tools are acceptable. The Ekahau product runs on a PC and uses a WLAN network interface card (NIC) to collect data for analysis. The output of the tool is a number of robust visualizations of the network. The software verifies the basic coverage of the network and provides a number of visualizations that are useful for VoWLAN deployments.

Perform capacity planning using the data rate analysis view, which shows a color-coded view of the maximum data rate across all APs in the network. With this view, you can see where your handsets can use the 11 Mb/s data rate as opposed to scaling down to lower rates. Planning based on data rate can have a big impact on voice-call-capacity planning.

Predict AP selection and roaming using the strongest AP view. This view shows the AP with the strongest signal for each location in the building and uses color codes for each AP. With the AP view, you can predict the APs that are likely to be the primary choice of voice devices to use given their location. You can also predict where the handoff to another AP (and which AP) can occur for a moving user.

Perform resiliency planning through the AP reachability view. This view presents a color-coded visualization of the number of reachable APs from each point in the network. Locations where the tool detects one AP, locations where the tool detects two APs, locations where the tool detects three APs, and so on, are marked in distinct colors. With this visualization, you can see where the network is vulnerable to a single point of failure. It is preferable to have at least two APs that are capable of offering coverage to every point in the building.

You can also use the AP reachability view to perform location service planning. A minimum of three APs must be reachable for triangulation to be effective. Therefore, use the AP reachability feature to verify a consistent 3+ AP coverage across the building.

Location capabilities have a number of client dependencies, so verifying triangulation coverage is more complex than it appears. There are two main location-solution types:

•those that use the client to collect information about the APs in the network (client-based location)

•those that use the APs to collect information about the client (network-based location)

Nortel Communication Server 1000

WLAN IP Telephony Installation and Commissioning

NN43001-504 01.02 Standard

Release 5.0 15 June 2007

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