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Wireless Telecommunication Facilities Master Plan - Town of Morrisville, NC – Adopted July 23, 2013
B-3
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Forecasting future infrastructure needs based on the status of the existing deployments
and population trends.
Basic coverage predictions and wireless coverage handoff
CityScape provides a series of maps to help visualize the number of antenna locations that would
be necessary to provide wireless communications coverage across the geographic study area. To
accomplish this task, CityScape has created a series of root mean square (RMS) theoretical
coverage and handoff maps by randomly selecting existing antenna locations throughout the
Town. This hypothetical network demonstrates the minimum number of base station locations
required for one provider to provide complete coverage. In order to complete this analysis an
antenna mounting elevation must be determined. CityScape has reviewed the existing tower
regulations and inventory for the Town and determined the average tower height of the towers
used for wireless telecommunications purposes to be around 199 feet tall. Thus, 199 feet was
chosen for the mounting elevation for the theoretical coverage master plan maps.
According to the Okumura-Hata propagation path loss formula coverage for 800 MHz, a
reasonable coverage area for an antenna mounted at 199 feet for cellular deployment on flat
terrain is about 4.5 miles. This means a single antenna mounted at 199 feet with flat terrain and
minimal subscribers would provide a wireless signal to an approximate 5.1-mile geographic
radius. Figure 1 illustrates that it requires one tower centrally located within the Town to provide
complete 800 MHz cellular coverage to the defined geographic study area. This site represents a
theoretical build-out for antennas mounted at the 199-foot elevation at equal dispersion, in a
perfect radio frequency environment, with no consideration of adjacent community wireless
deployment for a single cellular provider
and excluding topographic and population variables
.
The black dot within the circle indicates the antenna location. The smaller circle shown within
the larger circle represents the limits of the search area for locating the tower. The one cell would
theoretically provide wireless service throughout the study area for one provider to address
coverage objectives and not capacity objectives.
Referring to the “COST-231” formula for 1900 MHz a reasonable coverage area for an antenna
mounted at 199’ feet for a PCS site on flat terrain is approximately 2.6 miles. The coverage
reduction form 5.1 miles to 2.6 miles reflects the variable change from 800 MHz to 1900
megahertz. Figure 2 illustrates it would take up to three antenna locations to cover the same
geographic area as in Figure 1. These 1900 MHz PCS sites represent a theoretical build-out of
one antenna mounted at the 199-foot elevation at equal dispersion for one PCS provider;
with no
dispersion for one PCS provider;
with no consideration of terrain or demographic variables.