Nortel Networks NN43001-504 manual Site survey, Site Survey mode

Access point planning 41

A site survey is critical to designing and implementing a wireless LAN. The site survey is used to determine the number of APs needed to support the wireless handset users and to determine the best placement of the APs.

Different AP vendors provide different tools to do this.

Site survey

To conduct a site survey, set up an AP at a particular location. Use a computer equipped with a wireless LAN device and site survey software or a handset operating in Site Survey mode to measure the strength of the signal from the AP. Move the wireless device around and repeat the measurements to determine the optimum number and best locations for the APs. This method helps identify dead zones and areas where building materials or other factors affect the performance of the network.

Site Survey mode

The handset Site Survey mode displays negative dBm levels. These levels represent the strength of the received signal (Received Signal Strength Indication or RSSI) from an AP. The RSSI information aids in determining if WLAN coverage is adequate.

For information about using the Site Survey mode, see WLAN Handsets Fundamentals (NN43001-505).

Note: The handsets do not require connectivity to a 2245 IP Telephony Manager or the Call Server to enable the Site Survey mode to be used. The minimum configuration required is the Extended Service Set Identifier (ESSID) of the WLAN or test AP and the WEP keys, if applicable.

Access point requirement considerations for b radio

Each site is unique in its AP requirements. Consider the following points when determining how many APs are needed and where to place them:

•Minimum Radio Signal Strength—All APs in the coverage area must receive a signal strength better than -70dBm. Measurement is made in negative dBm, which measure the amount of signal loss due to distance. Therefore, stronger signals are those with smaller values. For example, -50 and -60 indicate stronger signals than -70; -80 is a weaker, poorer signal than -70.

•Adjacent APs and channel interference—In order to avoid undesirable interference from adjacent APs, ensure that adjacent APs do not use channels that overlap on the same frequencies.

For more information, see Figure 3 "Frequencies used by b radio" (page 42). In the figure, channels on the same horizontal line do not overlap. In the coverage area of any given AP, signals from other APs using overlapping channels must be at least -15 to -20dBm weaker. Because

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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