Showing papers on "Co-channel interference published in 1971"

Cochannel interference rejection in a mobile radio space diversity system

Abstract: Diversity is often used in radio systems to alleviate the problem of fading. It is shown here that the use of diversity in a mobile radio system also will result in better utilization of the frequency spectrum. In a system which reuses channels in physically separated areas, probability distributions of signal-to-cochannel interference ratios in 1-, 2-, and 4-branch diversity systems are developed by Monte Carlo methods. We consider two cases: first, we assume signal strength to be Rayleigh distributed, which is a valid model for reception within a small localized area; second, we take shadow losses into account by assuming a more realistic long-term fading model. The effect of using diversity in a mobile radio system is considerable with either model. Assuming a hexagonal cell pattern of frequency reuse, it is shown that frequencies may be reassigned more often in a diversity system than in a system which does not use diversity. The conclusion, therefore, is that a diversity system utilizes the frequency spectrum more efficiently than an equivalent nondiversity system.

Radio Channel Characterization

Abstract: The critically increasing demand for radio frequency allocations has stimulated development of information needed to reexamine efficient use of the radio spectrum. The characteristics and limitations, of the radio channel, with emphasis on the transmission channel (propagation and noise), are discussed along with typical communication systems currently using the radio spectrum.