Transmission of information on a single carrier frequency in a full-duplex radio line

Abstract

Telecommunication communication is usually provided in duplex mode, which requires the provision of two carrier frequencies and at least twice the bandwidth of the radio channel in a wireless version (subject to a priori equality of the capacities of information sources at both ends of the radio line). Throughout the development of wireless telecommunications technologies, the issue of the efficiency of using the frequency spectrum allocated for transmitting/receiving messages is acutely relevant, namely, reducing the bandwidth occupied by the message. This task has significant limitations, primarily based on minimizing the distortion of transmitted messages that may occur when artificially limiting the bandwidth. Information compression/compaction methods provide some savings in the width of the frequency spectrum, but a marginal reduction in the occupied frequency band can be achieved when the receiving and transmitting paths of both directions operate at the same carrier frequency. The article provides a brief overview of methods to improve the efficiency of using the frequency resource, provides a computer model and a study of the method of wireless information transmission that allows a full-duplex wireless communication channel to be implemented on a single carrier frequency. The above and investigated computer model of the method based on the use of a circulator made it possible to evaluate the effect of additive noise, the difference in amplitude and phase of the interference signal from the transmitter and a copy of the signal from the radio transmitter in "antiphase" on the number of errors (BER). According to the research results, it can be concluded that in order to reduce the number of errors when using a compensator, it is necessary to ensure an exact match of the interference signal from the transmitter and a copy of the signal from the radio transmitter in "antiphase" in amplitude and the phase difference between these signals is equal to 1800. Since an increase in the amplitude difference starting from 0.001 and the phase deviation from 0.10 from 1800 leads to a significant increase in the number of errors even with large values of the signal-to-noise ratio. In addition, when developing a device based on this method, it is necessary to take into account the difference in the amplitudes of the useful signal and "interference from the transmitter". This parameter specifies additional requirements for the device. The task of compensating for interference from the transmitter is simplified by the fact that the parameters of the transmitting signal and the characteristics of the device elements are known in advance.