Cell Tower Analysis

Santa Barbara, Ventura and Los Angeles Counties 

 

 The first map shows the distribution of cellular towers in these 3 counties and the second map shows cellular coverage in Los Angeles County.

         
 Data for this map was acquired from Federal Communications Commission (FCC) Universal Licensing System (ULS) database. The database utilized is “Cellular - 47 CFR Part 22 ‘Licenses’”, last updated (from when map was created) on 4/8/12. This is a non-comprehensive database for keeping track of licensed cell towers in North America. The data is unreliable and these maps were created as a class mapping exercise rather than as a serious geo-processing analysis. Comprehensive reliable data is difficult to find, however it is estimated that there are about 4,000 cell towers in Southern California. Based on the database used to create this map, there are 41 towers in Los Angeles, 32 in Santa Barbara and 18 in Ventura. These numbers are inaccurate and are more likely to be in the hundreds. 

Cellular Coverage in Los Angeles County

 

  Assignment:

You have been given a $30,000 budget to improve cell tower performance. You can do one of the following:
1. Add three additional towers at optimal locations;
2. Increase all the tower heights by 10 meters;
3. Increase the towers’ power resulting in an increase of each tower’s range by 5 km.


For each option, you will need to re-conduct the viewshed analysis in order to compare to your original results. (Remember to also compute the percentage of LA County that is able to receive cell signals from your analysis.) After you analyze and compare each of the above three options, which do you recommend. 

 The goal of this class assignment was to learn how to use the viewshed analysis technique. A viewshed identifies locations that can be seen from one or more observation locations. Since the data is inaccurate, this map is more about viewshed analysis techniques than the results. I ignored cell towers surrounding Los Angeles County and just focused on cell coverage in LA created by towers within the county boundary lines. If this analysis had been for a company, I would have taken into account that cell towers outside of the county lines may have a coverage range that overlaps into Los Angeles County, in which case this would have affected my statistics of total cell coverage percentage as well as my choice for placement of the three new towers. 

My first step in the analysis was to download digital elevation (DEM) model data of Los Angeles County from the USGS Seamless Data Warehouse. I then imported the DEM data into ArcMap and used the mosaic tool to link the two swaths together. I then overlaid the cellular tower point data and Los Angeles County boundary polygon on top of the elevation data and projected the layers into UTM Zone 11 (North American 1983 datum). I then appended the cell tower attribute table with the necessary parameters to conduct the viewshed analysis (OFFSETA, OFFSETB, AZIMUTH1, AZIMUTH2, VERT1, VERT2, RADIUS1, RADIUS2); I made the “normal coverage” OFFSETA (height of the tower) 20 meters, OFFSETB (height of cellphone user) 1.4 meters, and RADIUS2 (range of cell reception) 30,000 meters. I kept ArcGIS default values for the other parameters.

The next step was to conduct the viewshed analysis for each of the four scenarios (normal coverage, adding 10 meters to tower height, adding 3 new towers and increasing range of reception by 5000 m). I then used the extract by mask tool to only keep the viewshed data that was within the Los Angeles County boundary. The extract by mask tool only worked for the “normal coverage” and “add 3 new towers” maps for a reason unknown to me. I used a work around to accomplish the extraction for the “add 10 meters to tower heights” and “add 5 km coverage range” maps, I used the clip management tool and then integerized the raster output to obtain pixel counts. I created a hillshade of the DEM for map presentation purposes. 

Based on my final results, adding 3 new towers increased the coverage the most. The next most effective scenario was adding 10 meters to the tower heights closely followed by increasing cell range by 5 km. All three scenarios were improvements upon the results yielded by the original parameters.

View the presentation online here.