Site Selection Criteria in GSM
Site selection is based on a number of criteria. It may not be possible to satisfy all these criteria at the same time, but it is important to select the best sites available.
- Drive test sites should be selected to give a good representative sample of the system coverage area. The exact number of sites required will depend on the size of the system coverage area and the variability of the characteristics of the coverage area.
- All terrain and clutter types in the area should be represented in the drive test data for proper prediction tuning.
- Typical terrain types are: Flat, Rolling Hills, Large Hills, Mountains
- Typical clutter types are: Water, Open Land, Forest, Commercial / Industrial, Low Density Urban, Medium Density Urban, High Density Urban, City Center, Airport.
- City maps, topographical maps and aerial photographs can be useful in determining the terrain and clutter types for an area. It may also be necessary to drive the area and observe building types and density.
TEST SITE SELECTION
- Test sites must be available for use during the drive test.
- The site owner/supervisor should approve access to the site for as long as needed to complete the testing. This may involve multiple visits to the site, possibly on short notice.
- Test sites must also be physically accessible to allow setup of the transmitter equipment and mounting of the antenna. For this reason building top sites are preferred to tower sites.
- Each site selected should be visited before testing to verify that is suitable for use.
- The inspection should be done by the same people who will be doing the site setup for the actual drive test. Familiarity with the site should speed up the site setup during the drive test.
BUILDING SITE SELECTION
- When inspecting a building site the rooftop should be checked for any obstructions that would interfere with signal propagation. This could include objects on the rooftop itself or other nearby buildings or structures.
- The antenna location should be selected and a sketch of the rooftop made to identify this location relative to other objects nearby.
- Photographs should be taken of the location where the antenna will be mounted and in all directions looking away from the site.
TOWER SITE SELECTION
- When inspecting a tower site the best location to mount the antenna to the tower must be deter-mined.
- This should be selected such that the tower doesn’t interfere with the propagation pattern of the transmit antenna. This will usually require that the antenna be above the tower or on an arm extending from the side of the tower.
- The area around the tower should be checked for any obstructions that would interfere with signal propagation.
- Generally cranes are used for temporary structure.
- When cranes are used power generators have to be arranged in advance.
- The location should be selected such that the antenna will be above any nearby obstacles.