阅读说明：本技术 多波束系统中利用极化的空间复用方法及装置 (Spatial multiplexing method and apparatus using polarization in multi-beam system ) 是由 吴泰烈 沈埈亨 允敏先 崔栽荣 权景勋 文荣灿 崔午硕 于 2020-12-02 设计创作，主要内容包括：本发明公开了多波束系统中利用极化的空间复用方法及装置。根据本发明的一实施例,提供一种空间复用方法,其在多波束系统中使用极化,该方法包括以下步骤：决定用于第一波束和第二波束的不同相位和不同极化；对信号进行预编码(precoding)以使所述第一波束和所述第二波束分别具有上述决定的不同相位；以及对所述经过预编码的信号进行极化转换以使所述第一波束和所述第二波束分别具有上述决定的不同极化。(The invention discloses a spatial multiplexing method and a spatial multiplexing device utilizing polarization in a multi-beam system. According to an embodiment of the present invention, there is provided a spatial multiplexing method using polarization in a multi-beam system, the method including the steps of: determining different phases and different polarizations for the first beam and the second beam; precoding a signal so that the first beam and the second beam have different phases determined above, respectively; and polarization-switching the precoded signals so that the first beam and the second beam have different polarizations determined above, respectively.)

1. A method of spatial multiplexing using polarization in a multi-beam system, the method comprising the steps of:

determining different phases and different polarizations for the first beam and the second beam;

precoding a signal so that the first beam and the second beam have the determined different phases, respectively; and

polarization-switching the precoded signals so that the first beam and the second beam have the determined different polarizations, respectively.

2. The spatial multiplexing method according to claim 1, further comprising a step of mapping the precoded signal to resource elements,

the converting step includes the step of polarization-converting the signal mapped to the resource element.

3. The spatial multiplexing method according to claim 1, further comprising a step of mapping the polarization-converted signal to resource elements.

4. The spatial multiplexing method according to claim 1, wherein said converting step comprises the step of converting the polarizations of the precoded signals into orthogonal cross polarizations (± 45 degrees) and orthogonal vertical/horizontal polarizations.

5. The spatial multiplexing method according to claim 4, wherein said converting step comprises the step of converting the polarization of the precoded signal into the orthogonal cross polarization (± 45 degrees) and the orthogonal vertical/horizontal polarization using the following mathematical expression.

In the numerical expression, a and b represent any one of the orthogonal cross polarization (± 45 degrees) and the orthogonal vertical/horizontal polarization, a + b and a + be^jπRepresents the other of the orthogonal vertical/horizontal polarization (± 45 degrees) and the orthogonal vertical/horizontal polarization.

6. A spatial multiplexing apparatus that uses polarization in a multi-beam system, the apparatus comprising:

a control section that determines different phases and different polarizations for the first beam and the second beam;

a beam forming unit that pre-codes a signal so that the first beam and the second beam have the determined different phases, respectively; and

a multi-polarization combining unit that performs polarization conversion on the precoded signal so that the first beam and the second beam have the determined different polarizations, respectively.

7. The spatial multiplexing apparatus according to claim 6, further comprising a resource element mapping section that maps the precoded signal to a resource element, the multipolar synthesis section polarization-converts the signal mapped to the resource element.

8. The spatial multiplexing apparatus according to claim 6, further comprising a resource element mapping section that maps the polarization-converted signal to resource elements.

9. The spatial multiplexing apparatus according to claim 6, wherein the multipolar synthesis section converts polarizations of the precoded signals into orthogonal cross polarizations (± 45 degrees) and orthogonal vertical/horizontal polarizations.

10. The spatial multiplexing apparatus according to claim 9, wherein the multipolar synthesis section converts the polarization of the precoded signal into the orthogonal cross polarization (± 45 degrees) and the orthogonal vertical/horizontal polarization by using the following mathematical expression.

In the numerical expression, a and b represent any one of the orthogonal cross polarization (± 45 degrees) and the orthogonal vertical/horizontal polarization, a + b and a + be^jπRepresents the other of the orthogonal vertical/horizontal polarization (± 45 degrees) and the orthogonal vertical/horizontal polarization.

Technical Field

The present invention relates to a method and apparatus for implementing spatial multiplexing, and more particularly, to a method and apparatus for spatial multiplexing capable of improving communication quality by minimizing interference between polarizations and using polarizations in a multi-beam system.

Background

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

In a multi-beam system (e.g., a Massive MIMO (multiple-input and multiple-output) system), a correlation coefficient of a radio channel is increased due to interference between adjacent beams, and thus, a problem occurs in that spatial resources cannot be effectively used.

Recently, multi-beam systems have reduced interference between adjacent beams by using antenna modules with different polarizations to allow adjacent beams to use different polarizations.

However, this method requires the antenna modules for the respective polarizations to be used to be formed separately, and thus has problems of complicated manufacturing process and requiring a large amount of time and cost. Further, this method requires separately forming antenna modules for each polarization to be used, and therefore has a problem of increasing the size of the antenna.

Disclosure of Invention

Technical problem to be solved

It is a primary object of an embodiment of the present invention to provide a method and apparatus for reducing interference between adjacent beams by changing the phase of I/Q data (In-phase/Quadrature-phase data) at a baseband using orthogonal polarization of antennas to adopt different polarizations between multiple beams used In spatial multiplexing.

(II) technical scheme

According to an embodiment of the present invention, there is provided a spatial multiplexing method using polarization in a multi-beam system, the method including the steps of: determining different phases and different polarizations for the first beam and the second beam; precoding a signal so that the first beam and the second beam have different phases determined above, respectively; and polarization-switching the precoded signals so that the first beam and the second beam have different polarizations determined above, respectively.

According to another embodiment of the present invention, there is provided a spatial multiplexing apparatus using polarization in a multi-beam system, the apparatus including: a control section that determines different phases and different polarizations for the first beam and the second beam; a beam forming unit that performs precoding (precoding) on a signal so that the first beam and the second beam have the determined different phases, respectively; and a multi-polarization combining unit that performs polarization conversion on the precoded signal so that the first beam and the second beam have the determined different polarizations, respectively.

(III) advantageous effects

According to an embodiment of the present invention, adjacent beams have different polarizations, so that interference between adjacent beams is reduced, thereby improving communication quality.

In addition, according to another embodiment of the present invention, by improving the orthogonality of the wireless channel, the channel capacity of the system can be increased.

Drawings

Fig. 1 is an exemplary block diagram of a spatial multiplexing device capable of implementing the techniques of this disclosure.

Fig. 2 is a flowchart for explaining the spatial multiplexing method of the present invention.

Fig. 3 is a diagram for explaining an example of spatial multiplexing achieved by the present invention.

Fig. 4 is a block diagram for explaining an example of a spatial multiplexing apparatus capable of implementing the technique of the present disclosure.

FIG. 5 is a block diagram illustrating the multipolar synthesis of the present invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. When reference is made to reference numerals, the same reference numerals are used as much as possible even if the same technical features appear in different drawings. Also, it is to be noted that throughout the specification, detailed descriptions thereof will be omitted if it is considered that specific descriptions of related known technical features and functions may cause the subject matter of the present invention to be unclear.

In describing the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only used to distinguish one technical feature from another technical feature, and are not used to limit the nature, order, sequence, or the like of the technical features. Throughout the specification, if a technical feature "comprises" or "comprising" another technical feature, if not specifically stated to the contrary, it is understood that one technical feature also comprises the other technical feature, and it is not understood that one technical feature excludes the other technical feature. In addition, terms such as '… part', 'module' and the like described in the specification mean a unit capable of processing at least one function or action, and they can be implemented by hardware or software, or by a combination of hardware and software.

The present invention provides a method and apparatus capable of generating or setting various polarizations by changing the phase of I/Q data (In-phase/Quadrature-phase data) on a baseband using orthogonal polarizations of antennas.

In addition, the present invention provides a method and apparatus for improving orthogonality of radio channels and increasing channel capacity of a system by using different polarizations between adjacent beams in order to implement spatial multiplexing in a mobile communication system using multiple beams (e.g., a multi-beam system, such as a Massive MIMO system).

Fig. 1 illustrates an example of a spatial multiplexing device 100 for implementing the method. The configuration of the spatial multiplexing device 100 and the spatial multiplexing method using the spatial multiplexing device 100 will be described below with reference to fig. 1 and 2.

The spatial multiplexing device 100 may be disposed on at least one of a base station, a relay, and a terminal. As shown in fig. 1, the spatial multiplexing device 100 may include a control section 110, a beam forming section 120, a multipole combining section 130, and an RF link 140(RF chain). Also, the RF chain 140 may include an RF block (not shown) and an orthogonally polarized antenna module. The RF block (not shown) may include a digital to analog converter (DAC)/analog to digital converter (ADC), a filter, and a mixer (mixer).

The number of beamforming sections 120, multipole combining sections 130, and RF chains 140 may be greater than or equal to the number shown in fig. 1. For example, when spatial multiplexing is implemented by using a larger number of beam patterns (beams), the spatial multiplexing apparatus 100 may include more than the number of beamforming units 120, multipole combining units 130, and RF chains 140 shown in fig. 1.

The control section 110 can set or decide the phase and polarization of the beam to be radiated through the RF link 140.

The control section 110 may set or determine that each beam has a different phase. For example, when the number of beams used for spatial multiplexing is n (n is a natural number of 2 or more), the control unit 110 may determine that the n beams have different phases. The phase determined by the control unit 110 can be used for beamforming by the beamforming unit 120.

Further, the control unit 110 may determine that spatially adjacent ones of the plurality of beams have different polarizations (different polarizations). For example, when the number of beams used for spatial multiplexing is n (n is a natural number of 2 or more), the control unit 110 may set or determine that the adjacent kth beam and the l (k + l) th beam have different polarizations.

The beamforming part 120 may precode (precoding) the baseband signal or data S240.

The beam forming unit 120 can generate the beam (beamforming) determined by the control unit 110 by applying a weight vector (weight vector) to the baseband signal. The beamforming part 120 precodes signals so that each beam has a phase decided in the control part 110, so that the beams may have different phases based on the operation of the beamforming part 120.

The multi-polarization combining part 130 may polarization-convert the precoded signal S250.

The multipolar combining unit 130 performs polarization conversion on the precoded signals by a conversion process (combining or decomposing) described later, and thereby makes spatially adjacent beams have different polarizations (polarizations determined by the control unit).

The baseband signal may be processed by the scrambling process S210, the modulation process S220, the layer mapping process S230, and the like before being processed by the beamforming unit 120.

The scrambling procedure S210 is a procedure of encrypting a baseband signal with a scrambling signal in order to distinguish a base station or a User Equipment (UE). The spatial multiplexing device 100 may further include a scrambling module (not shown) that performs the scrambling process S210.

The modulation process S220 is a process of modulating the scrambled signal into a plurality of modulation symbols. The spatial multiplexing device 100 may further include a modulation module or a modulation mapper (not shown) for performing the modulation process S220.

The scrambled signal is input to a modulation mapper (not shown) and modulated by Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), or 16 quadrature amplitude modulation/64 Quadrature Amplitude Modulation (QAM) according to the kind of the signal and/or the channel state in S210.

The layer mapping process S230 is a process of mapping modulation symbols to at least one transmission layer in order to divide a signal by different antennas. The spatial multiplexing device 100 may further include a layer mapper (not shown) for performing the layer mapping process S230.

The spatial multiplexing device 100 can also perform a process S260 of mapping the modulation symbols obtained through the modulation process S220 to resource elements (to frequencies). For this, the spatial multiplexing device 100 may further include a resource element mapping part (not shown), and the process S260 of mapping to resource elements may be performed at the resource element mapping part (not shown).

To generate the polarization-converted signal-dependent time domain symbols, the spatial multiplexing device 100 may perform an Inverse Fast Fourier Transform (IFFT) algorithm. The spatial multiplexing device 100 may insert a guard interval (guard interval) S270 in order to prevent inter-symbol interference (ISI). For this purpose, the spatial multiplexing device 100 may further include an IFFT unit (not shown) and a Cyclic Prefix (CP).

The signals performing the processes S210 to S270 may be radiated in a beam form through the RF link 140. As described previously, beams radiated based on the spatial multiplexing method of the present invention have different phases in space, and adjacent two beams among the beams of different phases may have different polarizations.

Fig. 3 illustrates an example of beams radiated according to the spatial multiplexing method of the present invention. In fig. 3, the beams (beam #1, beam #3, beam #5, and beam #7) indicated by the solid lines have polarization directions of ± 45 (orthogonal cross polarization), and the beams (beam #2, beam #4, beam #6, and beam #8) indicated by the broken lines have polarization directions of V/H (vertical/horizontal polarization).

If beam #1 uses orthogonal cross polarization (+ -45), then beam #2 uses vertical/horizontal polarization (V/H). In the same way, if beam #3 uses orthogonal cross polarization (+ -45), then beam #4 uses vertical/horizontal polarization (V/H).

That is, the present invention can reduce the correlation coefficient between adjacent beams by using different polarizations (different polarizations) between adjacent beams instead of using the same polarization. Also, the different polarizations may use any type of polarization that is mutually orthogonal, such as left circular polarization/right circular polarization.

Since the beam #1 having orthogonal cross polarization (+ -45) and the beam #2 having vertical/horizontal polarization (V/H) have different polarizations, the correlation between the beam #1 and the beam #2 can be sufficiently small. Moreover, since the beam #1 is kept at a sufficient distance from the beam #3 having orthogonal cross polarization (± 45), the correlation between the beam #1 and the beam #3 is sufficiently small.

According to an embodiment, the order of the process S250 of polarization conversion of the signal and the process S260 of mapping to the resource element may be changed. For example, (1) the process of polarization transformation of the signal S250 is performed first and then the process of mapping to resource elements S260 is performed; (2) the process of mapping to resource elements S260 is performed first and then the process of polarization converting the signal S250 is performed.

In case (1), the multi-polarization combining part 130 may polarization-convert the precoded signals to have different polarizations, and the resource element mapping part (not shown) may map the polarization-converted signals to resource elements. In case (2), the resource element mapping part (not shown) may map the precoded signals to the resource elements, and the multi-polarization combining part 130 may polarization-convert the signals mapped to the resource elements to have different polarizations.

The spatial multiplexing method is explained below based on two beams (a first beam and a second beam) with reference to fig. 4. It is assumed that the first beam and the second beam have different phases in space (first beam: first phase, second beam: second phase) and are adjacent and have different polarizations (first beam: ± 45 degrees, second beam: V/H).

When it is desired to radiate the first beam and the second beam through the RF link 140, the control section 110 determines that the first beam and the second beam have different phases and that the first beam and the second beam have different polarizations.

The beam forming unit 120 may apply the weight vector to the baseband signal so that the first beam and the second beam have the phases determined by the control unit 110, respectively.

For example, the beamforming units #1-1(BF #1-1, 122-1), #1-2(BF #1-2, 122-2), #1-3(BF #1-3, 122-3) and #1-4(BF #1-4, 122-4) may set the phase of the signal to a first phase and output the signal to the multi-polarization combining unit #1-1(PD #1-1, 132-1). Furthermore, the beamforming units #1-1(BF #1-1, 122-1), #1-2(BF #1-2, 122-2), #1-3(BF #1-3, 122-3) and #1-4(BF #1-4, 122-4) may set the phase of the signal to the second phase and output the signal to the multi-polarization combining units #1-2(PD #1-2, 132-2).

The multi-polarization combining unit 130 may perform polarization conversion on the precoded signals so that the first beam and the second beam have the polarization (different polarization) determined by the control unit 110, respectively.

For example, the multi-polarization combining part #1-1(132-1) may convert the polarization of the signal set to the first phase to ± 45 degrees, and the multi-polarization combining part #1-2(132-2) may convert the polarization of the signal set to the second phase to V/H.

Signals (set) having a first phase and a polarization of ± 45 degrees may be radiated in a first beam through RF link #1-1(142-1) and RF link #1-2(142-2), and signals (set) having a second phase and a polarization of V/H may be radiated in a second beam through RF link #1-3(142-3) and RF link #1-4 (142-4).

In this specification, the orthogonally polarized antenna modules included in the RF chain 140 use antenna modules arranged at +45 degrees and-45 degrees. However, any antenna module of various types, such as orthogonal polarization antenna modules arranged in V (vertical) and H (horizontal), may be used in the present invention as long as the antenna modules are arranged in mutually orthogonal form.

The spatial multiplexing method of the transmission signal is explained above. The spatial multiplexing method with respect to the received signal may be performed in reverse order to the spatial multiplexing method of the transmitted signal.

The polarization conversion method of the present invention will be explained with reference to fig. 5.

As described above, the multi-polarization combining part 130 may polarization-convert the precoded signals to have different polarizations. The different polarizations may include, among others, orthogonal cross polarization (+ -45) and orthogonal vertical/horizontal polarization (V/H).

The process of converting the polarization of the signal into a different polarization can be achieved by the following mathematical formula 1.

[ mathematical formula 1]

In the above mathematical formula 1, a and b represent any one of orthogonal cross polarization (± 45) and orthogonal vertical/horizontal polarization (V/H), a + b and a + be^jπRepresents the other of orthogonal cross polarization (+ -45) and orthogonal vertical/horizontal polarization (V/H),

representing a Polarization Decomposition (PD) matrix.

For example, if PD matrices are employed in +45 degree polarization a and-45 degree polarization b, they can be converted into +45 degree polarization a and-45 degree polarization b, and vertical polarization a + b and horizontal polarization a + be^jπDifferent polarization of (a).

Fig. 2 illustrates that the processes S210 to S270 are sequentially performed, but this is merely an example to illustrate the technical idea of an embodiment of the present invention. In other words, it will be apparent to those having ordinary skill in the art to which an embodiment of the present invention pertains that modifications and variations can be made by changing the order of fig. 2 or performing at least one of the processes S210 to S270 in parallel without departing from the essential features of an embodiment of the present invention, and the order in fig. 2 is not limited to the clockwise order.

In addition, the steps of fig. 2 may be embodied in computer-readable code on a computer-readable recording medium. The computer-readable recording medium may include all kinds of recording devices that store data readable based on a computer system. That is, the computer-readable recording medium may include a magnetic storage medium (e.g., read only memory, floppy disk, hard disk, etc.), an optical readable medium (e.g., CD-RDOM, DVD, etc.), and a storage medium of a carrier wave (e.g., internet-based transmission). In addition, the computer readable medium is dispersed in computer systems connected through a network and stores and executes codes readable by a computer in a dispersed manner.

The above description is only for illustrating the technical idea of the present embodiment, and it is obvious to those skilled in the art that various modifications and variations can be made without departing from the essential characteristics of the present embodiment. Therefore, the present embodiment is not intended to limit the technical idea of the present embodiment but to illustrate, and the scope of the technical idea of the present embodiment is not limited to the embodiment. The scope of the present embodiment should be construed based on the claims, and all technical ideas within the equivalent scope thereof are included in the scope of the present embodiment.

Cross Reference to Related Applications

This patent application claims priority from korean patent application No. 10-2019-0160606, filed on 5.12.2019 and korean patent application No. 10-2020-0046256, filed on 16.4.2020, and is incorporated herein by reference in its entirety.