ould be avoided, and in extreme cases may dictate a choice between 2.4 and 5 GHz operation. Implementing Wireless LANs Table 7-8: Propagation and Signal Strength Survey Survey aspect Description Objective Identify the coverage pattern, received signal strength and achievable data rate for given access point and client station locations within the WLAN operating area. Equipment used Laptop or handheld PC equipped with wireless interface card and site survey software. Ideally the survey receiver hardware should be identical to the planned client station hardware (same wireless NIC), otherwise allowances will need to be made, for example for differing receiver sensitivity or antenna gain. Combining the survey tool with a GPS navigation module can help in transferring measurements onto site plans. Survey Site walk-through test following preliminary access point technique placement, measuring received signal strength and maximum data rate at each location. If both 2.4 and 5 GHz operation are under consideration, the survey will need to be conducted in each band, as propagation patters will differ widely between these bands. Application of Results will show how the ideal omnidirectional propagation survey results pattern is affected by the operating environment (office partitions, walls, cabinets, lift shafts, etc.). Achievable data rate versus range will dictate the required placement of access points as input to planning the physical hardware layout. Figure 7-1 shows a typical display of propagation and signal strength survey results, which can be used to identify areas where RF propagation is adversely affected by local environmental conditions. Combined with a similar graphical display of noise floor measurements this will give an indication of potential low SNR areas, which may need to be addressed by adjusting access point or antenna locations or by changing transmitter power settings or antenna gain. Designing the Physical Architecture Having built up a picture of the RF environment and gathered data on propagat