Some alternative frequency assignment procedures for mobile radio systems

Channel assignment procedures for mobile radio systems are usually based on the assumption of equal spacing in frequency between all available channels, and it is customary to argue that the growing demands for greater numbers of channels in the limited spectrum available must be met by dividing the present separation interval of 12.5 kHz by two. Such a measure would however demand major changes in the specification and design of equipment and the purpose of the present paper is to consider alternative strategies for channel frequency assignment which might increase the available number of channels while making less stringent demands on improvements in equipment performance. A typical computed result shows that, by reducing channel bandwidth by 20% and utilizing an assignment strategy based on multiples of a 2.5 kHz increment, the bandwidth needed to accommodate eight channels with freedom from third-order intermodulation interference is reduced from 437.5 kHz to 200 kHz.