The site survey is the first step in designing an in-building distributed antenna System (DAS). This blog entry will look at what happens during a Cartel Cellular Site Survey and explain the benefits of having one of our technicians taking measurements onsite to help engineer your DAS.
The first step in Cellular SIte Survey is the walk test. Our technician will walk through the entire facility with a cellular scanner to determine existing coverage strength and quality of the signal for each carrier, frequency band, and technology (such as UMTS or LTE) you request. The information collected is analyzed and used to determine what areas require enhancmene tand what amplitude is needed based on your requirements. in large urban areas, for instance, at least 10 dB of the dominance of the in-building system sectors are needed to exceed the signals entering the buidling. Those extra 10 dB reduce interference and prevent handoffs between the in-buidling system and the macro sites around it, ensuring users can count on good quality signals and data rates.
Next, propagation tests may be performed by injecting a continuous wave signal into an antenna at specific locations in the facility. That signal is measured to analyze the propagation at different frequencies and will determine the attenuation of physical obstructions (such as walls, beams, sculptures). This data is then recorded and used to inform the engineering design by determining the required antenna density and location.
Once the RF data is collected, our technician begins a physical investigation of the building to determine the best route for the installation of the passive and active equipment. Telecom rooms, for instance, are visited to see if they might host the headend equipment. Ceiling composition is studied to determine if conduit is required (as is the case with exposed concrete ceilings) or if plenum rated cable can be run (above a drop ceiling or drywall). Existing cable trays, risers, and conduit also could be utilized to run cable and provide potential antenna locations. In the case of an off-air system, the rooftops is visited to take off-air measurements with a directional antenna and to determine donor antenna location and cable pathway into the building to the potential headend telecom rooms.
Cartel takes the RF data, details ascertained from the building investigation, images from the onsite survey, and creates a comprehensive Cellular Site Survey package that includes all the information required to put together a preliminary design package for your in-building DAS.
Although much work can be done throught software modelling, it is impossible to exceed the accuracy of a Cartel Cellular Site Survey, especially when the structural composition of the building is uncertain or evolving building codes and improving materials exceed the assumptions that software can make.
Andrew DePodesta, Project Specialist