Calculation of the average value of mutual information in the Rayleigh channel

In the subarctic regions, decameter radio lines are actively used to transmit information on weather conditions. As a rule, information is transmitted by means of frequency telegraphy with speeds of about 50 Baud, using powerful radio transmitting devices. In addition, telegraphic communication is used in aviation and in the navy, so, despite the fact that decameter radio communication is a backup type of communication, the load of this range is quite high. As a result, collisions are often observed due to the variability of the ionosphere, when the receiver's input receives signals simultaneously from two sources of information. This situation can be considered from the perspective of the operation of the radio line in the conditions of interference unintentional nature. Given that unintentional interference, in most cases, is a signal similar in structure to the useful signal, its destructive nature will be manifested in the imposition of information embedded in it. Taking into account these circumstances, it is required to estimate the level of mutual information values arising in the receiving channel with Rayleigh distribution from two sources of signals with close structure, one of which is an unintentional interference. An expression for calculating the total average mutual information for two signals with close structure, one of which is an unintentional interference in the Rayleigh channel is obtained. In accordance with the obtained expression, the average value of mutual information in the Rayleigh channel is determined not only by the variance of the useful signal and unintentional interference, but also by their average values. The results of the theoretical study and analytical modeling showed that in the conditions of mutual interference with a close frequency-time structure in the Rayleigh channel the most difficult situation occurs when the average values of the useful signal and unintentional interference are equal. This is explained by the fact that in conditions of deep fading, characteristic of the Rayleigh channel, the ratio of dispersions of the useful signal and interference become not so significant. Since the operation of telegraph radio lines is characterized by aperiodicity, and the used antenna systems have extraordinarily wide radiation patterns, it is rather difficult to solve the problem of minimizing the destructive impact of unintentional interference only through organizational measures. Therefore, compensation of mutual interference is required in accordance with the obtained expression.