Method of spatial multiplexing in multi-antenna communication systems

Reliability of the communication system with spatial multiplexing has been studied. Increasing the bandwidth of radio communication channels due to spatial multiplexing is one of the most popular and relevant areas of modern research in the field of radio communications. Solving the problem of spatial multiplexing in the time domain with multipath propagation is associated with a significant increase in the dimension of the problem and redundant calculations. Detection in the time domain makes it difficult to take into account the frequency dependence of the amplitude and phase of the received signals, which in turn reduces the probability of correct signal recognition. In multipath propagation, a solution to the problem of spatial multiplexing in the frequency domain is proposed by applying the convolution theorem. The probability of error is estimated when using the proposed detection method. The stability of the solution is estimated depending on the conditionality of the matrix of amplitude-phase parameters. The expression of the estimation of the upper bound of the error probability in the subchannel is derived depending on the number of conditionality of the matrix of amplitude-phase parameters and the spectral density of noise in physical communication channels. An algorithm for adaptive formation of matrices of amplitude-phase parameters has been developed which selects such antennas among an excessive number of receiving antennas allowing to increase the stability of detection by reducing the number of conditionality of the matrix of coefficients of a system of linear equations. The theoretical basis of the spatial multiplexing method in multi-antenna communication systems has been developed. The proposed method makes it possible to increase the efficiency of calculations by reducing the dimension of the detection problem in comparison with the solution in the time domain. It is proposed to solve the detection problem only at frequencies at which a useful signal is expected to be received, which is especially useful for narrow-band frequency and phase, orthogonal and biorthogonal types of modulation often used in multi-antenna digital communication systems. Expressions for estimating the probability of error in the subchannel are derived. An algorithm for adaptive formation of matrices of amplitude-phase parameters has been developed, which makes it possible to increase the stability of the solution of the detection problem. The research results are applicable in the development of multi-antenna communication systems with spatial multiplexing.