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and provides consistent coverage.
Performing a site survey can minimize the possibility of dead spots. The AP equipment provider can usually perform a site survey. While many tools exist that allow customers to perform their own assessment, SpectraLink recommends that every site employ a professional site survey to ensure optimum coverage and minimize interference.
Site surveys are a necessity for large or complex facilities. An extensive site survey will ensure that the minimum number of APs are deployed, but at the risk of having to significantly reconfigure the network if the coverage area is remodeled. Wi-Fi infrastructure providers are making significant developments to reduce the time, cost, and complexity of determining AP locations. Because the cost of APs has significantly dropped over the last few years, in some cases it is more cost effective to install more APs with overlapping coverage rather than try to maximize coverage for each AP with a rigorous site survey.
To verify coverage with an existing Wi-Fi network, NetLink Wireless Telephones offer a site survey mode that can be used to test the AP’s signal strength in the wireless LAN coverage area. This mode detects the four strongest AP signals and displays the signal strength and the AP channel assignments. This mode can be used to detect areas with poor coverage or interfering channels. With the NetLink e340 and i640 Wireless Telephones, the entire coverage area should be checked to ensure that at least one access point’s reading is stronger than –70 dBm in all areas. Also, if the site survey mode indicates 2 APs using the same channel, then at least one other AP must be indicated at 10 dBm stronger than those APs to avoid channel conflicts. After a site survey is completed, coverage issues can be resolved by adding and/or relocating APs and overlap issues may be resolved by reassigning channels or by relocating some access points. Another complete site survey should be performed after any adjustments are made to ensure that the changes are satisfactory and have not impacted other areas.
All APs on the wireless network used by the NetLink Wireless Telephones must be set to the same supported and basic data rates. If this is not adhered to, the NetLink Wireless Telephones may not associate to the closest AP if a more distant one supports a higher data rate.
In addition, all APs must be set to operate at the same power output. SpectraLink highly recommends a power output setting of 100 mW. If this cannot be accommodated, SpectraLink recommends a 50 mW setting and requires a minimum of 30 mW. With lower power output settings, special attention must be made to AP placement to ensure there are no frequency re-use issues. These problems may not be evident when using the handset’s site survey tool as it is assumes 100 mW transmission power from the APs.
