System for and method of assigning frequencies in a communications system with no central control of frequency allocation

In a communication system comprising a plurality of base sites comprising transmitter and receiver means and a plurality of mobiles comprising transmitter and receiver units which can be selectively operated on a plurality of frequency channels, a method of making frequency channel assignment of said mobiles to said base sites by real time signal comparisons without reference to a geographical pattern and without use of a central frequency assignment control said method consisting of conducting the following tests before making a frequency channel assignment to a new, that is to be assigned, mobile:

• a. determining whether signal transmissions from a new base site, that is the base site to which said new mobile is to be assigned will cause interference at a previously assigned mobile,
• b. determining whether said new mobile will be interfered with by signal transmissions from a previously assigned base site,
• c. determining whether said new base site will be interfered with by signal transmissions from a previously assigned mobile, and
• d. determining whether signal transmissions from said new mobile causes interference at a previously assigned base site;
• and, making said channel assignment.