Digital-to-analog hybrid beamforming method based on uplink training

Abstract

The present invention belongs to the technical field of wireless communication, and relates to a digital-to-analog hybrid beamforming method based on uplink training. The method of the invention mainly comprises the following steps: sending by a user terminal a training sequence of a certain length, and receiving by a base station a training signal which travels via free space and is subjected to noise interference; and forming an optimal estimation of the training sequence; through the assumption that the BS knows the training sequence, establishing an objective function wherein the solution of the function is the optimal beamforming matrix; using the reciprocity of the uplink and downlink free-space travel channels to regard the optimal beamforming matrix obtained from the uplink training as the optimal beamforming matrix for the downlink transmission; and then through matrix decomposition, obtaining the beamforming matrixes of the analog domain and the digital domain. The technical schemes of the invention are to eliminate some interference in the analog domain, utilize and improve the idea of orthogonal matching and tracking, search the analog domain beamforming matrix in the codebook set, and finally solve the digital domain beamforming matrix by the least squares method.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, and relates to a digital-analog hybrid beamforming method based on uplink training. Background technique [0002] Millimeter wave (mmWave) communication technology has become a new research key technology in the field of 5G wireless communication. There are a large number of unused frequency bands in the millimeter wave band, which provides great potential for further improving system capacity. And because the wavelength is small, a large number of antenna elements can be packaged in a small physical form, so that it has perfect adaptability in a large-scale multiple input multiple output (Multiple Input Multiple Output, MIMO) system. Large-scale antenna arrays can provide sufficient shaping gain to overcome the high path loss in mmWave communications and achieve better link performance. Therefore, mmWave massive MIMO systems will receive increasing attention in 5G research. [0...

AI Technical Summary

Problems solved by technology

In fact, a generalized channel is composed of a free-space propagation channel and a transceiver circuit, and generally speaking, the transceiver circuit does not have reciprocity, especially in the hybrid beamforming structure. Therefore, using the reciprocity of TDD There is also no guarantee of getting a full CSI

In summary, regardless of FDD or TDD, it is very difficult to obtain complete CSI under the hybrid beamforming structure

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