Cell Phone Tower Coverage Analysis in Los Angeles County

The objective of this exercise is to study the cell phone coverage of Los Angeles county. First, I will calculate the current cell phone coverage of LA county, and then explore options to improve the coverage. Finally, I will recommend a plan based upon the results obtained from the study, and the funds of $30,000 available to implement the plan.

The aim of the analysis is to identify one of the three options that would be most effective in improving cell phone coverage in the LA county. The three options available to improve the coverage are: (1) add three additional towers at optimal locations, (2) increase all the tower heights by 10 meters, and (3) increase each tower range by 5 km.

Digital Elevation Model (DEM) data was acquired from the USGS site by selecting an area that also included surrounding area to LA county. This is done because cell phone towers near the boundary of LA county will also provide coverage to neighboring areas. The USGS DEM downloaded had a resolution of 30 m, but viewshed analysis is computationally expensive, so the DEM data was aggregated using a geoprocessing tool in ArcGIS Spatial Analyst to a coarser resolution of 90 meters. A hillshade was created from the resampled DEM by using the HillShade geoprocessing tool for reference purposes.

The cell tower point map created for Lab 1 was used as a default. Eight new fields was added to attribute table to the existing map namely, OFFSETA, OFFSETB, AZIMUTH 1, AZIMUTH2, VERT1, VERT2, RADIUS1, and RADIUS2. Default values were used for all fields, except OFFSETA (tower height) and and RADIUS2 (range of tower).  First, a viewshed was created with default values only. This was followed by creating viewsheds for following options: (1) tower height field OFFSETA was set to 30 m and other values were default, and (2) range of tower was increased by setting the RADIUS2 field to 35,000m, and other values were default. Finally, population map was overlaid on viewshed to identify areas of dense population. Several locations were tried, but in terms of people covered, densely populated areas were found to be an attractive options. More detailed study at lower resolution is suggested to arrive at better results. To calculate area, the viewshed raster was converted into polygon shapefile, and it was then clipped to the shape of LA county that included only the inland areas. The following table provides the summary of results from all three options.

	Options	Total Area	Coverage (sq m)	Coverage (%)	Not Covered (%)
1	Original, no change	10,322,955,900	4,095,732,600	39.6	60.4
2	Range increased 5k	10,322,955,900	4,671,650,700	45.2	54.8
3	Tower height 30 m	10,322,955,900	4,254,452,100	41.2	58.8
4	Three new towers	10,322,955,900	4,225,786,200	40.9	59.1

Maps were created for all these options. As seen in the maps, the option of new towers covers more people as these towers are located in densely populated areas. Other options of increasing tower range and height cover more area in the county, but may have lesser number of people covered. This needs to be studied. The goal of the exercise was to be maximize the coverage area. Based on the above results from viewshed analysis, and assuming that equipments needed to improve the cell phone tower can be purchased using the funds of $30,000 available, I recommend the option to increase the range of cell phone towers for greater coverage in Los Angeles County. However, if more people were to be covered, the option to add new towers should be considered