Patent ID: 6301482
Filing Date: 2001-10-09
Classification: H04W

Abstract:
A cellular Demand Access Multiple Access radio communications system comprising pluralities of terminal stations and base stations having transponders and antennas, and a master station, whereinstationary terminal stations' antennas are directive so as to reduce the number of other terminal stations and base stations whose signals they can intercept,the base station transponder and terminal stations within each cell are preassigned a subset of the available frequency channels,control signals are transmitted bidirectionally between each base station antenna and each of its terminal stations,the strengths of received direct signals, co-channel interfering signals and noise are measured during these transmissions, and stored in a master station communicating with all base stations, results of said measurements being used, upon request from a terminal station for assignment of a communication channel, to determine whether any available channel can meet the terminal user's requirements for co-channel, adjacent channel interference and noise;wherein control of signal quality is ensured by passing control signals between base and terminal stations, monitoring the interference and noise levels in the receivers, storing the results digitally in the master station, and using programmed logic to select an optimum channel and signal level for each assignment;wherein said programmed logic selects an optimal channel assignment by searching for a frequency channel that is not effectively jammed by a communication channel previously assigned, nor will it jam other previously assigned channels; andwherein said programmed logic evaluates and creates an optimum channel assignment by the process of initially creating an ordered table for each terminal, listing for each assignable channel, any angular sector(s) of other base stations which would be co-channel jammed by that terminal assignment; on each request for channel assignment by a terminal, if the requesting terminal is one that is capable of interfering with other sectors, finding and selecting the last channel in the table that is jammed in an interfering sector but unjammed and currently unused in the present sector; if there is no such channel, searching for the last channel unjammed in an interfering sector; if there is no such channel, blocking the assignment, if the requesting terminal is not capable of interfering with others, finding and selecting the first channel in the table that is presently unassigned and unjammed in the present sector, selecting and assigning it; if there is none, blocking the assignment.