AUTONOMOUS ADAPTIVE FREQUENCY ASSIGNMENT FOR TDMA PORTABLE RADIO SYSTEMS

To assign and coordinate radio frequencies at the fixed facilities (radio ports) of a frequency-reusing radio communications system, most existing methods require pre-engineering or impose high complexity in system controller and port hardware. A simple autonomous procedure performed by each radio port to determine its own frequency is proposed. This procedure consists of signal strength measurements and an algorithm which selects the frequency with minimum interference from other ports. The algorithm stabilizes the frequency plan rapidly, while adapting to changes of operational conditions, such as installing new ports which changes the system configuration or adding new buildings which causes different shadow fading. This method is significantly superior to a random assignment method both in resultant channel quality and in traffic-handling capability. For a regular-grid configuration, this method performs nearly as well as an a priori optimal frequency assignment method. It is also found that this assignment algorithm is robust against short-term signal fluctuations and it can be performed completely autonomously by each radio port.