The pre-installation site survey has long been a core element of wireless-LAN deployments. The concept is simple: Set-up an access point, and, running a site-survey application on a mobile computer, walk around, noting signal strength in various locations in order to build a coverage map.
Then use the data to deploy production access points for optimal coverage. While early deployments were indeed optimised for coverage because of high capital-equipment costs, today’s WLAN deployments need to be much more concerned with capacity. That’s because WLANs must support potentially large numbers of users with a diverse application base requiring ever-greater throughput over time. Plus, dramatically larger deployments in more challenging physical layouts, and the mission-critical nature of today’s enterprise WLANs add to the complexity.
All enterprise-class WLAN products today include some form of sitesurvey capabilities. However, at least a partial installation of the system to be purchased is required before these can be used. For this reason, and because a wide range of site-survey strategies can be applied, a number of third-party site-survey tools have appeared in the market.
There are four types of site survey tools: Spectral sweep, predictive, analytical and production monitoring. This article focuses on predictive and analytical tools.
Predictive tools use sophisticated RF modelling techniques to simulate the performance of a hypothetical WLAN system without the requirement for actually installing any real equipment.