Viewshed Analysis of Cell Towers

          Because of the growing dependence on cell phones in today’s society, especially in large cities, cell phone reception is very important. In Los Angeles, many people use cell phones to keep in touch with families, friends, coworkers and clients. However, according to the map, only 55.1% on Los Angeles county area has cell phone coverage. We are always looking for ways to improve cell coverage in the County. With only a $30,000 budget, creating maps that show either three additional towers, towers with extended height, and towers with extended range, will help us figure out which way to improve cell performance will be the most effective. From the calculations taken from the map, adding three additional towers will increase the percent of cell coverage in Los Angeles County.

          To begin with making the maps, I first acquired a digital elevation model of Los Angeles County and the cell tower coordinates from the Universal Licensing system from the FCC website (www.fcc.gov). I added data to the excel table so that all fields have 20 meter tower height, 2 meter cell phone user height and have a tower radius of 30,000 meters. From there I added the DEM into ArcMap and set the projection to UTM Zone 11N and coordinate system to WGS 1984. Then I added XY data, the table with the cell tower locations and set the projection and coordinate system accordingly. Next, I created the viewshed using the spatial analysis toolbar. Then, I converted the raster of the viewshed into a polygon layer to represent the colors better. In the attribute table, there were numbers ranging from 0-12, 0 being anything not visible, and 1-12 being anything visible. I changed all the numbers 2-12 to 1 and then dissolved the polygon layer. From there, I went into the symbology tab under properties of the polygon viewshed and changed the “not visible” color to white and the “visible” color to a green. Now I have the areas of cell phone coverage for Los Angeles County. For the other three maps, I had the same procedures, except I computed the excel table differently to project different data. I added three new towers at these coordinates: 34.066, -118.346; 33.881, -118.395; and 34.079, - 118597. I chose these locations because these where areas that had patchy coverage but had high populations. For the extended tower height map I changed the height from 20 meters to 30, and for the extended range map I changed the radius from 30,000 to 35,000.

          As a result, I calculated the area of each coverage map in the attribute table and added them up and divided to find the percentage of covered area. I came to find that right now, 55.1% of Los Angeles has cell phone coverage. With the three new towers it is increased to 58%. The extended height map increased to 56.5% and the extended range increased to 56.1%. Therefore, my conclusion is that adding three cell towers to the map would add the most amount of covered area. Most importantly, I chose the cell tower locations to be in area that have people living in those areas so that the added cell coverage is not in vain. In conclusion, by adding three tower locations to Los Angeles County, cell coverage will be increased the most and therefore people of the area will benefit the greatest.

Sources:

http://seamless.usgs.gov/website/seamless/viewer.htm 

http://wireless.fcc.gov/

By Chelsea Kemp

April 19, 2011