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The WiFi site survey process is a key step to ensure your WiFi network is designed appropriately and ensures that the system meets your requirements, present and future, when implemented. Benjamin Franklin's saying "Failure to prepare is preparing to fail" is all too true for many sites who skimp on this first and most important stage in the wireless project.
The key ingredient to be able to conduct a successful WiFi site survey is experience. DW WiFi has served its apprenticeship in wireless technology having designed and implemented numerous wireless systems in the days before WiFi was invented. The process has evolved over a period of time as technology has advanced and been adapted to overcome typical issues that face RF (Radio Frequency) technology such as interference.
DW WiFi have observed and monitored the performance of manufacturers of WiFi access points over the years and have adopted Cisco as their preferred products. This is partly in recognition of Cisco's strong reputation in communications but mainly due to their acquisition of Aironet Wireless Communications in 1999 whos technology was widely considered 'best of breed'.
Pre-WiFi Site Survey Questionnaire
DW WiFi provides a Pre-Site Survey Questionnaire. This document gathers the requirements of the partner and their end user customer. It is imperative that a plan of the site is provided at this stage onto which the partner company, in conjunction with their end user customer, is asked to shade in the areas of the site where radio coverage is required. The importance of this is clear for all parties concerned in that this approach determines the remit of the WiFi site survey and ensures that no areas of the site are overlooked.
This questionnaire document is usually perceived as useful to the customer in that it raises questions such as the data throughput speed required, the type of clients proposed and whether or not the system will be 'mission critical' and hence require some form of redundancy.
DW WiFi uses the completed questionnaire to assess the resources required in order to successfully conduct the site survey. The majority of WiFi site surveys at end user sites can be completed in a single day (including travelling to and from site). Circumstances can sometimes dictate otherwise, for example where access is restricted or where the site is extensive. DW WiFi provides a firm quotation at this stage and provides a selection of available calendar dates to conduct the WiFi site survey. The dates are on a 'first come first served' basis, a date being secured on receipt of a purchase order.
 WiFi Site Survey
On arrival at the customer site a pre-survey meeting is held with the customer to confirm the requirements detailed in the pre-survey questionnaire. The site survey is then conducted using a Cisco model 1242 IEEE 802.11abg access point housed inside an IP66 rated enclosure box. this allows for surveys to be conducted outside in poor weather conditions. The ACC-APENCL Enclosure Box is designed and available for purchase from DW WiFi. This is mounted to an extendable tripod and powered using a mobile power supply.
 The photograph (left) shows an area of the site being surveyed using 'patch' directional antennas to focus radio reception in front of the wall on the picture. A Cisco 802.11abg wireless adapter card is installed in a laptop computer and configured to connect to the test access point. The Cisco Site Survey Utility software (screen shot below right) is then used to monitor signal levels at strategic points within the required coverage areas of the site. The DW WiFi engineers are able to call on experience of conducting many WiFi site surveys in similar environments to carefully plan suitable locations of the access points. The choice of antenna type and location is key in optimising coverage. The objective of the WiFi site survey as a whole is to provide good signal quality in the required areas of the site. An important consideration is to avoid 'co-channel interference' a phenomenon whereby two access points configured to the same radio channel are co-located and hence a source of interference to each other. This can be minimised by careful planning of the type and placement of the access points and antennas.
Mitigating Against Interference
DW WiFi has learned through experience that other WiFi networks (often present at end user sites in office areas) can be a source of interference to the proposed wireless network. WiFi technology is also vulnerable to interference from radio transmissions at frequencies in the 2.4 GHz range occupied by WiFi. This is often overlooked and can lead to issues later in the project. DW WiFi opts to try and identify these issues at the site survey stage and has invested in WiFi software tools (Air Magnet and Wi-Spy) to help identify any potential interference issues. These wireless tools are also used to great effect as part of our WiFi Trouble-Shooting service.
When the site survey is complete the DW WiFi engineer conducts a post survey meeting with the end user customer to ensure all requirements have been addressed and discuss the findings of the survey. With the customer's permission, our engineer will take digital photographs of the proposed locations for each of the access points and antennas. Theses photographs will be used to compile a comprehensive site survey report.
WiFi Site Survey Report
 The WiFi site survey report is considered of paramount importance by DW WiFi in that it represents the deliverable documentation received by the end user customer. It is completed and submitted to the partner company 2-3 days after the WiFi site survey has been conducted. We offer the service of producing the report to our customer's specifications including their company logos, banners etc. The report is very detailed and includes a summary of the required WiFi equipment and accessories. This enables the partner company to very quickly provide a hardware quotation to their customer and subsequently source the hardware from their preferred supply. DW WiFi can, on request, make recommendations on suppliers.
Assuming the end user places an order for the hardware on our partner company the next step is for the end user site to be prepared in readiness for the WiFi hardware to be installed and configured. The WiFi site survey report is compiled to enable a cabling contractor to install the data cabling and install the WiFi hardware. The diagrams (left) are an example of the level of detail provided in the site survey report to assist the cabling company in their task.
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