Communication system employing a nine channel pattern allocation to eliminate interference

DETAILED DESCRIPTION I claim: 1.
A communication system, comprising: a plurality of ground stations disposed in first, second, and third substantially parallel rows, the ground stations being substantially evenly spaced within each row and the spacing between the ground stations being substantially the same for all the rows, the rows being disposed so that a pair of adjacent ground stations in the first row, a pair of adjacent ground stations in the third row, and two ground stations in the second row which are separatated by an intervening ground station of the second row are disposed substantilly at the vertices of a regular hexagon, wherein each ground station is assigned a channel selected from the set consisting of channel number 1, channel number 2, channel number 3, channel number 4, channel number 5, channel number 6, channel number 7, channel number 8, and channel number 9, wherein the ground stations in each row are assigned channel number in accordance with the repeating sequence 1, 3, 5, 7, 9, 2, 4, 6, 8, and wherein the channel assignments for the ground stations of each row are offset so that the intervening ground station in the second row, and the closest ground stations in the first and third rows which have the same channel number as that of the intervening ground station, lie substantially along a straight line which is disposed at an angle of about 20.
degree.
with respect to the rows.




Description:
BACKGROUND OF THE INVENTION This invention relates to communication systems and more particularly to systems having a network of fixed base stations with which mobile terminals communicate.
In communication systems in which each base station is allocated a frequency channel for communication, it is necessary to ensure that those stations operating on the same channel are separated by a large enough distance so as to reduce any interference between them to acceptable levels.
Interference may also occur between base stations operating on adjacent frequency channels