Radio telephone transmission system - isolates high density traffic area with ring of unique channels in surrounding area to avoid common channel interference

摘要

In a radiotelephone system covering a zone of low density traffic with an island of high density traffic such as a city, the zone is divided into cells (1-9) with each group of three adjacent cells being served by three directional antennas mounted at the same spot, preferably three triplets of cells forming a motif (1-9). The island is divided into a central cell (A) surrounded by preferably six cells (A, B, C, D) using three sets (B, C, D) of channels unique to the six cells with the two cells using the same set being at opposite sides of the ring. The central cell (A) has an omnidirectional central antenna, the cell (A) being able to use all or nearly all of the channels (1-9) of the overall zone without risk of interference. The channels (B, C, D) of the six ring cells are used by directional antennas at three locations on the edge of the central cell. The system provides adequate coverage of the high density area without risk of interference in the zone between common channels.