Cellular Network Organization

Use multiple low-power transmitters (100
W or less)
Areas divided into cells
oEach served by its own antenna
oServed by base station consisting of
transmitter, receiver, and control unit
oBand of frequencies allocated
oCells set up such that antennas of all neighbors
are equidistant (hexagonal pattern)

Frequency Reuse
Adjacent cells assigned different
frequencies to avoid interference or
crosstalk
Objective is to reuse frequency in nearby
cells
o10 to 50 frequencies assigned to each cell
oTransmission power controlled to limit power at
that frequency escaping to adjacent cells
oThe issue is to determine how many cells must
intervene between two cells using the same
frequency

Frequency Assignment Problems
Cellular systems provider allocates frequencies
from a licensed spectrum
Constraints:
oFor any cell, interference from nearby cells within an
acceptable minimum
oFor any cell, the frequency bandwidth allocated sufficient
to support the load in the cell
Objectives:
oMinimize the total bandwidth (or width of the spectrum)
allocated across all cells
oMinimize call blocking probability
oMinimize average interference