Non-orthogonal polarization MIMO communication system

Abstract

The invention discloses a non-orthogonal polarization MIMO (Multiple Input Multiple Output) communication system, which belongs to the technical field of wireless communication and comprises a serial-parallel conversion and precoding module, a signal distribution network, a transmitting channel, a non-orthogonal transmitting array antenna, a non-orthogonal receiving array antenna, a receiving channel, a signal merging network and an MIMO signal detection module, a non-orthogonal transmitting antenna unit is arranged in the non-orthogonal transmitting array antenna, and a non-orthogonal receiving antenna unit is arranged in the non-orthogonal receiving array antenna. According to the invention, parallel transmission of multiple paths of signal streams can be realized under various channel conditions, and the transmission rate and the spectrum utilization rate of the system are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, more particularly, to a non-orthogonal polarization MIMO communication system. BACKGROUND

[0002] With the continuous development of communication technology, the research focus gradually expands from the traditional time-frequency domain to the space domain, giving birth to the MIMO communication system that can support multi-stream spatial multiplexing, which can significantly improve the system spectrum utilization, and has been widely used in 5G mobile communication. Although the MIMO communication system has many advantages, in the line-of-sight communication scenario, the channel often presents Gaussian / quasi-Gaussian characteristics, and the correlation of each received signal is strong, so the spatial multiplexing degree will be greatly limited, and it is difficult to support multi-stream parallel transmission. And the multi-user MIMO communication system can only improve the network capacity between the base station and multiple terminals, and it is difficult to solve the problem that the transmission rate and spectrum efficiency between the base station and a single terminal are restricted by the channel conditions. With the rapid development of future high-definition video, artificial intelligence (AI), augmented reality (AR) and other applications, the massive data generated puts forward higher demand for the transmission rate of the wireless communication system, and how to further improve the spectrum utilization of the MIMO communication system has become a research hotspot in recent years.

[0003] The prior art cannot well support multi-stream spatial multiplexing in the case of strong channel correlation, and it is difficult to further improve the spectrum efficiency and transmission rate of the MIMO communication system. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide a non-orthogonal polarization MIMO communication system that can realize multi-stream parallel transmission under various channel conditions and improve the system transmission rate and spectrum utilization.

[0005] The purpose of the present application is achieved by the following scheme: A non-orthogonal polarization MIMO communication system, comprising: a serial-parallel conversion and precoding module, a signal distribution network, a transmission channel, a non-orthogonal transmission array antenna, a non-orthogonal receiving array antenna, a receiving channel, a signal combining network and a MIMO signal detection module, wherein the non-orthogonal transmission array antenna is provided with a non-orthogonal transmission antenna unit, and the non-orthogonal receiving array antenna is provided with a non-orthogonal receiving antenna unit. At the transmitting end, the transmitting baseband signal is processed by a serial-to-parallel conversion and precoding module, and then divided into multiple transmitting signals by a signal distribution network, processed by multiple transmitting channels, and transmitted by multiple non-orthogonal transmitting antenna units in a non-orthogonal transmitting array antenna; at the receiving end, multiple receiving signals are received by multiple non-orthogonal receiving antenna units in a non-orthogonal receiving array antenna, processed by receiving channels, combined by a signal combination network, and finally processed by a MIMO signal detection module to obtain a receiving baseband signal.

[0006] Further, each non-orthogonal transmitting antenna unit has different polarization characteristics; each non-orthogonal receiving antenna unit has different polarization characteristics; and each non-orthogonal receiving antenna unit simultaneously receives signals transmitted by multiple non-orthogonal transmitting antenna units with different polarization characteristics.

[0007] Further, the non-orthogonal transmitting array antenna comprises at least four non-orthogonal transmitting antenna units with different polarization characteristics; and the non-orthogonal receiving array antenna comprises at least four non-orthogonal receiving antenna units with different polarization characteristics.

[0008] Further, the non-orthogonal transmitting array antenna comprises M non-orthogonal transmitting antenna units, and the non-orthogonal receiving array antenna comprises N non-orthogonal receiving antenna units; based on the difference in polarization characteristics, each non-orthogonal transmitting antenna unit and each non-orthogonal receiving antenna unit have different and independent coupling coefficients, and the following system transmission model is established accordingly: ; wherein, is the array antenna receiving signal, is the channel transmission matrix, is the antenna coupling coefficient matrix, is the array antenna transmitting signal, is the matrix point multiplication, is the matrix multiplication, and the antenna coupling coefficient matrix is expressed as: ; wherein, is the coupling coefficient between the receiving antenna unit i and the transmitting antenna unit j , , ; The maximum value of the elements in the antenna coupling coefficient matrix is greater than twice the minimum value, i.e., it satisfies: ; The difference between the maximum value and the minimum value of the elements in the antenna coupling coefficient matrix is greater than 1 / 2 of the average value of all elements, i.e., it satisfies: .

[0009] Further, the transmission power of each non-orthogonal transmission antenna unit is different. The transmission power of each non-orthogonal transmission antenna unit is different.

[0010] Further, the transmission power of each non-orthogonal transmission antenna unit is different. The calculation process of the transmission power is as follows: The antenna coupling coefficient matrix is calculated according to the following formula: The sum of each column coefficient is: : ; The reciprocal of is calculated according to the following formula: : : ; The normalized coefficient of is calculated according to the following formula: : : ; The transmission power of each non-orthogonal transmission antenna unit is calculated according to the following formula: : .

[0011] Further, the polarization of each corresponding antenna unit of the non-orthogonal transmission array antenna and the non-orthogonal receiving array antenna is non-orthogonal.

[0012] The beneficial effects of the present application include: The present application has a high spatial multiplexing degree, thereby realizing parallel transmission of multiple signal streams, improving the system transmission rate and spectral utilization rate, and being particularly suitable for application in a line-of-sight MIMO wireless communication system. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0014] Figure 1 A structure diagram of a non-orthogonal polarization MIMO communication system according to an embodiment of the present application; Figure 2 A flow chart for calculating the transmission power of each transmission antenna unit in the non-orthogonal transmission array antenna in the MIMO communication system shown in Figure 1 Figure 3 ​for Figure 1 An exemplary implementation block diagram of a nonorthogonal transmit / receive array antenna in the MIMO communication system shown; Figure 4 for Figure 1 An exemplary implementation block diagram of a non-orthogonal transmit / receive antenna unit in the MIMO communication system shown; Figure 5 for Figure 1 An exemplary implementation block diagram of a non-orthogonal transmit / receive antenna unit in the MIMO communication system shown; Figure 6 for Figure 1 An exemplary implementation block diagram of a non-orthogonal transmit / receive antenna unit in the MIMO communication system shown; Figure 7 This is a schematic diagram comparing the bit error rate of the MIMO communication system proposed in this embodiment of the invention with that of a conventional MIMO communication system under a line-of-sight Gaussian channel. Figure 8 This is a schematic diagram comparing the bit error rate of the MIMO communication system proposed in this embodiment of the invention with that of a conventional MIMO communication system under a Rayleigh channel. In the figure, there are serial-to-parallel conversion and precoding module 101, signal distribution network 102, transmission channel 103, non-orthogonal transmission array antenna 104, non-orthogonal transmission antenna element 105, non-orthogonal receiving array antenna 106, non-orthogonal receiving antenna element 107, receiving channel 108, signal combining network 109, and MIMO signal detection module 110. Detailed Implementation

[0015] All features disclosed in all embodiments of this specification, or steps in all methods or processes implied in the disclosure, may be combined and / or extended or replaced in any way, except for mutually exclusive features and / or steps.

[0016] The specific implementation process of this invention is as follows: like Figure 1As shown, in the preferred embodiment, the application specifically proposes a non-orthogonal polarization MIMO communication system, which comprises a serial-parallel conversion and precoding module 101, a signal distribution network 102, a transmitting channel 103, a non-orthogonal transmitting array antenna 104, a non-orthogonal transmitting antenna unit 105, a non-orthogonal receiving array antenna 106, a non-orthogonal receiving antenna unit 107, a receiving channel 108, a signal combination network 109, and a MIMO signal detection module 110. At the transmitting end, the transmitting baseband signal is processed by the serial-parallel conversion and precoding module, then divided into M transmitting signals by the signal distribution network, and transmitted by the M non-orthogonal transmitting antenna units in the non-orthogonal transmitting array antenna after frequency conversion, filtering, amplitude and phase adjustment, amplification, etc. The signals transmitted by each transmitting antenna unit are not completely orthogonal. At the receiving end, due to the independence of the antenna coupling coefficients, even if the channel correlation is strong, the N receiving signals received by the N non-orthogonal receiving antenna units in the non-orthogonal receiving array antenna still exhibit weak correlation. After amplification, amplitude and phase adjustment, frequency conversion, filtering, etc. by the receiving channel, the N receiving signals are combined by the signal combination network, and finally the receiving baseband signal is obtained after processing by the MIMO signal detection module.

[0017] Unlike conventional dual-polarized or multi-polarized array antennas, each non-orthogonal transmitting antenna unit 105 in the non-orthogonal transmitting array antenna 104 of the application has different but not necessarily orthogonal polarization characteristics; each non-orthogonal receiving antenna unit 107 in the non-orthogonal receiving array antenna 106 also has different but not necessarily orthogonal polarization characteristics, and each non-orthogonal receiving antenna unit 107 can simultaneously receive signals transmitted by multiple non-orthogonal transmitting antenna units 105 with different polarization characteristics.

[0018] The non-orthogonal transmitting array antenna 104 is composed of M non-orthogonal transmitting antenna units 105, and the non-orthogonal receiving array antenna 106 is composed of N non-orthogonal receiving antenna units 107; the non-orthogonal transmitting array antenna 104 contains at least four non-orthogonal transmitting antenna units 105 with different polarization characteristics; the non-orthogonal receiving array antenna 106 contains at least four non-orthogonal receiving antenna units 107 with different polarization characteristics.

[0019] Due to the different polarization characteristics, each non-orthogonal transmitting antenna unit 104 and each non-orthogonal receiving antenna unit 106 has different and independent coupling coefficients, and the system transmission model established accordingly is: ; wherein, is the array antenna receiving signal, is the channel transmission matrix, is the antenna coupling coefficient matrix, is the array antenna transmitting signal, for matrix multiplication, for matrix multiplication, the antenna coupling coefficient matrix is represented as: ; wherein, is the coupling coefficient between the receiving antenna unit i and the transmitting antenna unit j , , ; it can be known from the system transmission model that even if the channel correlation is strong, due to the independence of the antenna coupling coefficient, the multiple receiving signals still present weak correlation, and thus can better support multi-stream parallel transmission.

[0020] It is further illustrated that the maximum value of the elements in the antenna coupling coefficient matrix must be greater than 2 times the minimum value, that is, it must satisfy: ; the difference between the maximum value and the minimum value of the elements in the antenna coupling coefficient matrix must be greater than 1 / 2 of the average value of all elements, that is, it must satisfy: ; By the above limitation, the correlation between the multiple receiving signals can be reduced.

[0021] As shown in Figure 2 , each transmitting antenna unit 105 in the non-orthogonal transmitting array antenna 104 transmits power related to the antenna coupling coefficient matrix , so as to improve the system power efficiency, and the transmitting power is calculated as follows: Step s1: calculate the sum of each column coefficient of the antenna coupling coefficient matrix : ; Step s2: calculate the reciprocal of : ; Step s3: calculate the normalization coefficient of : ; Step s4: calculate the transmitting power of each non-orthogonal transmitting antenna unit: ; As shown in Figure 3As shown, the non-orthogonal transmitting / receiving array antenna can be designed separately or integrally, and the polarization non-orthogonality between the antenna units can be realized by using different polarization manners (linear polarization, circular polarization), different polarization directions (vertical / horizontal polarization, left-handed / right-handed circular polarization), different installation angles, different axial ratios, and non-standard polarization, so that the coupling coefficients between the non-orthogonal transmitting antenna units and the non-orthogonal receiving antenna units are different and independent.

[0022] Further, the non-orthogonal receiving / transmitting antenna units can adopt non-standard polarization manners such as irregular angle cutting, non-90° angle between the feed line / feeding point, and inconsistent amplitudes of multi-point feeding, to increase the difference between different polarizations, so that the coupling coefficients between the non-orthogonal transmitting antenna units and the non-orthogonal receiving antenna units have greater discrimination. For example, as shown in Figure 4 The standard angle cutting patch antenna unit cuts a square patch along the diagonal direction, while the non-orthogonal angle cutting patch antenna unit cuts along a direction different from the diagonal direction. As shown in Figure 5 The feed lines in the standard dipole antenna unit are perpendicular to each other, while the feed lines in the non-orthogonal dipole antenna unit are not perpendicular to each other. As shown in Figure 6 The angle between the feeding points in the standard double-feeding-point antenna unit and the center of the unit is 90 degrees, while the angles between the different feeding points and the center of the unit in the non-orthogonal double-feeding-point antenna unit are not equal to 90 degrees, or although the angles between the different feeding points and the center of the unit are 90 degrees, the electric bridge is not 90 degrees.

[0023] Due to the different polarization characteristics of the transceiving antenna units, under the line-of-sight communication condition, even if the channel transmission matrix has strong correlation between the elements, due to the independence of the coupling coefficient matrix between the elements, the correlation between the transceiving units is still weak, and the spatial multiplexing degree is still high, so that the multi-path signal stream parallel transmission is realized, the system transmission rate and the spectrum utilization rate are improved, and the design, development and production of the line-of-sight MIMO wireless communication system are particularly suitable.

[0024] Figure 7 The bit error rate comparison diagram of the MIMO communication system of the embodiment of the present application and the conventional MIMO communication system under the line-of-sight Gaussian channel; Figure 8 The bit error rate comparison diagram of the MIMO communication system of the embodiment of the present application and the conventional MIMO communication system under the Rayleigh channel. Through simulation, it can be seen that the bit error rate of the conventional MIMO communication system under the line-of-sight Gaussian channel is extremely large, and cannot be normally used, while the MIMO communication system with non-orthogonal polarization proposed by the present application has good bit error rate performance under the line-of-sight Gaussian channel, and the bit error rate under the non-line-of-sight Rayleigh channel is comparable to that of the conventional MIMO communication system.

[0025] The foregoing merely illustrates the principles of the application. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the foregoing discussion. It will be appreciated that those skilled in the art will be able to devise numerous arrangements which, although not explicitly described or shown herein, embody the principles of the application and are included within its spirit and scope. Therefore, to the extent there are variations of the application, which are within the spirit of the application, such are intended to be encompassed by the claims.

Claims

1. A non-orthogonal polarization MIMO communication system, characterized in that, include: The system includes a serial-to-parallel conversion and precoding module, a signal distribution network, a transmission channel, a non-orthogonal transmission array antenna, a non-orthogonal receiving array antenna, a receiving channel, a signal combining network, and a MIMO signal detection module. The non-orthogonal transmission array antenna is equipped with a non-orthogonal transmission antenna unit, and the non-orthogonal receiving array antenna is equipped with a non-orthogonal receiving antenna unit. At the transmitting end, the baseband signal is processed by the serial-to-parallel conversion and precoding module, and then divided into multiple transmission signals by the signal distribution network. After being processed by multiple transmission channels, the signals are transmitted by multiple non-orthogonal transmission antenna elements in the non-orthogonal transmission array antenna. At the receiving end, multiple non-orthogonal receiving antenna elements in the non-orthogonal receiving array antenna are used to receive multiple received signals. After being processed by the receiving channel, the multiple received signals are combined by the signal combining network, and finally processed by the MIMO signal detection module to obtain the received baseband signal.

2. The non-orthogonal polarization MIMO communication system according to claim 1, characterized in that, Each non-orthogonal transmitting antenna element has different polarization characteristics; each non-orthogonal receiving antenna element has different polarization characteristics; each non-orthogonal receiving antenna element simultaneously receives signals transmitted by multiple non-orthogonal transmitting antenna elements with different polarization characteristics.

3. The non-orthogonal polarization MIMO communication system according to claim 2, characterized in that, The non-orthogonal transmitting array antenna contains at least four non-orthogonal transmitting antenna elements with different polarization characteristics; the non-orthogonal receiving array antenna contains at least four non-orthogonal receiving antenna elements with different polarization characteristics.

4. The non-orthogonal polarization MIMO communication system according to claim 2, characterized in that, Suppose that the non-orthogonal transmitting array antenna consists of M non-orthogonal transmitting antenna elements, and the non-orthogonal receiving array antenna consists of N non-orthogonal receiving antenna elements; based on the differences in polarization characteristics, each non-orthogonal transmitting antenna element and each non-orthogonal receiving antenna element have different and independent coupling coefficients, and the following system transmission model is established accordingly: ； in, For the array antenna to receive signals, For channel transmission matrix, The antenna coupling coefficient matrix is... To transmit signals for the array antenna, For matrix dot product, For matrix multiplication, the antenna coupling coefficient matrix is... Represented as: ； in, For receiving antenna unit i With transmitting antenna unit j The coupling coefficient between them , ; Antenna Coupling Coefficient Matrix The maximum value of the elements in the set is greater than twice the minimum value, i.e., it satisfies: ； Antenna Coupling Coefficient Matrix The difference between the maximum and minimum values ​​of the elements is greater than half the average of all elements, which satisfies the following condition: 。 5. The non-orthogonal polarization MIMO communication system according to claim 4, characterized in that, Transmit power of each non-orthogonal transmitting antenna element They are all different.

6. The non-orthogonal polarization MIMO communication system according to claim 5, characterized in that, The transmission power The calculation process is as follows: Calculate the antenna coupling coefficient matrix using the following formula. Sum of coefficients in each column : ； Calculate using the following formula reciprocal : ； Calculate using the following formula normalized coefficients : ； Calculate the transmit power of each non-orthogonal transmit antenna element using the following formula. : 。 7. The non-orthogonal polarization MIMO communication system according to claim 2, characterized in that, The polarization of the corresponding antenna elements in the non-orthogonal transmitting array antenna and the non-orthogonal receiving array antenna is non-orthogonal.

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