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Wireless Telecommunication Facilities Master Plan - Town of Morrisville, NC – Adopted July 23, 2013
B-10
Service providers use base population estimates and subscriber data for their network
design. This combined information is what controls the separation distance between base
stations. The existing network design, based on local wireless penetration rates (the estimated
number of wireless subscribers) and usage, has each site facilitating the use of between 1750 and
2500 separate devices. As wireless devices increase in number
and
usage (particularly more
intensive bandwidth usage like email, Facebook, and mobile television), each site will need to
decrease
its geographic area and serve a smaller number of subscribers in order to avoid
overloading its systems. In other words, the 1750 to 2500 users per site will shrink significantly
over the next 10 years, with estimates ranging from 500 to 1200 devices per site, depending on
the particular carrier, services offered, and number of overall subscribers. Concurrent with the
shrinkage of number of users per site will be an increase in the total number of sites needed in
order to provide service to subscribers.
Environmental variables
Radio frequency propagation is also affected by vegetative cover. For example, pine needles
absorb radio frequency emissions which distort the propagation from the antenna. Leaf foliage
has a similar effect on propagation. Therefore, geographic land areas predominately covered by
deciduous vegetation will have improved network coverage in the winter when the leaves are off
the trees.
Land cover also affects propagation signal. As the signal travels across the land, trees and
buildings have the effect of weakening the signal. CityScape can illustrate the affect of these
variables.
Figures 5 and 6 illustrate how RMS service coverage is affected when the network capacity and
environmental variables are added to the propagation formulas. Network capacity considerably
shrinks the service area and the environmental variables further compromise the coverage area.
Geographic areas previously shown in green are reduced or eliminated indicating a loss of
coverage in that specific area.