Voice Over Wireless LAN 7-13
compliant APs, and so on) • It is unlikely that an existing WLAN will support a VoIP solution. Most WLANs will require new access points, switches, and network QoS 6. Verify AP locations. This is when the real testing begins. Use a site survey tool available from Motorola (Site Scanner) or from a third-party company. For example, Berkeley Varitronics Systems offers a line of handheld devices, such as Grasshopper, Scorpion, AirMagnet and Yellowjacket that provide advanced site survey functions. Install an AP at each preliminary location, and monitor site survey software readings by walking varying distances away from the AP. You do not need to connect the AP to the distribution system because the tests merely ping the AP. However, you need AC power. Note the data rates and signal readings at different points as you move to the outer bounds of the AP coverage. In a multi-floor facility, perform tests on the floors above and below the AP. A poor signal quality reading indicates that RF interference is affecting the Wireless LAN. This would warrant the use of a spectrum analyzer to characterize the interference, especially if there are no other indications of its source. Based on the results of the test, you may need to reconsider the location of some APs and redo the affected tests. 7. Ensure smooth transition from subnet to subnet. Find locations to place APs to insure seamless roaming throughout the building. 8. Document the findings. Once you are satisfied that the planned location of APs will provide adequate coverage, identify the recommended mounting locations on the facility diagrams.Installers will need this information. Also, provide a log of signal readings and supported data rates near the outer propagation boundary of each AP as a basis for future redesign efforts.