KR102309631B1 - Spatial multiplexing method and appatatus using polarization in multiple beams system - Google Patents

Abstract

Disclosed are a method and apparatus for spatial multiplexing using 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 comprising: determining different phases and different polarizations to be applied to a first beam and a second beam; precoding a signal so that each of the first beam and the second beam has the determined different phases; and converting the polarization of the precoded signal so that each of the first beam and the second beam has the determined different polarizations.

Description

SPATIAL MULTIPLEXING METHOD AND APPATATUS USING POLARIZATION IN MULTIPLE BEAMS SYSTEM

The present invention relates to a method and apparatus for implementing spatial multiplexing, and more particularly, to a method and apparatus for spatial multiplexing using polarized waves in a system using multiple beams capable of improving communication quality by minimizing interference between polarized waves will be.

The content described in this section merely provides background information on the present invention and does not constitute the prior art.

In a system using multiple beams (e.g., a massive multiple-input and multiple-output (MIMO) system), the correlation coefficient of a radio channel increases due to interference between adjacent beams, so that spatial resources are not used efficiently. There is a problem that cannot be

Recently, by employing antenna modules having different polarizations in a multi-beam system to configure adjacent beams to use different polarizations, interference between adjacent beams is reduced.

However, in this method, since an antenna module for each of the polarized waves to be used must be separately configured, the manufacturing process is complicated, which takes a lot of time and money. In addition, this method may have a problem in that an antenna size may be increased because an antenna module for each of the polarized waves to be used must be separately configured.

An embodiment of the present invention uses orthogonal polarization of an antenna to change a phase of I/Q data (In-phase/Quadrature-phase data) in a baseband, and a different polarization between a plurality of beams used for spatial multiplexing It is a main object to provide a method and apparatus capable of reducing interference between adjacent beams by applying .

According to an embodiment of the present invention, there is provided a spatial multiplexing method using polarization in a multi-beam system, the method comprising: determining different phases and different polarizations to be applied to a first beam and a second beam; precoding a signal so that each of the first beam and the second beam has the determined different phases; and converting the polarization of the precoded signal so that each of the first beam and the second beam has the determined different polarizations.

According to another embodiment of the present invention, there is provided a spatial multiplexing apparatus using polarization in a multi-beam system, comprising: a controller for determining different phases and different polarizations to be applied to a first beam and a second beam; a beamformer for precoding a signal so that the first beam and the second beam each have the determined different phases; and a multi-polarization synthesizing unit that converts the polarization of the precoded signal so that each of the first beam and the second beam has the determined different polarizations.

As described above, according to an embodiment of the present invention, since adjacent beams have different polarizations, interference between the adjacent beams is reduced, so that communication quality can be improved.

In addition, according to another embodiment of the present invention, since the orthogonality of the radio channel is improved, the channel capacity of the system can be increased.

1 is an exemplary block diagram of a spatial multiplexing apparatus capable of implementing the techniques of the present disclosure.
2 is a flowchart for explaining the spatial multiplexing method of the present invention.
3 is a diagram for explaining an example of spatial multiplexing implemented through the present invention.
4 is a block diagram illustrating an example of a spatial multiplexing apparatus capable of implementing the techniques of the present disclosure.
5 is a block diagram for explaining the multi-polarization synthesis of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the components from other components, and the essence, order, or order of the components are not limited by the terms. Throughout the specification, when a part 'includes' or 'includes' a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated. . In addition, the '... Terms such as 'unit' and 'module' mean a unit that processes at least one function or operation, which may be implemented as hardware or software or 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 in-phase/quadrature-phase data (I/Q) data in a baseband using orthogonal polarization of an antenna.

In addition, the present invention is configured to use different polarizations between adjacent beams for spatial multiplexing in a mobile communication system (multi-beam system, for example, a massive MIMO system) using a plurality of beams, thereby improving orthogonality of a radio channel. A method and apparatus for increasing the channel capacity of a system by improving the system are provided.

An example of the spatial multiplexing apparatus 100 for implementing these methods is shown in FIG. 1 . Hereinafter, a configuration of the spatial multiplexing apparatus 100 and a spatial multiplexing method using the spatial multiplexing apparatus 100 will be described with reference to FIGS. 1 and 2 .

The spatial multiplexing apparatus 100 may be installed in one or more of a base station, a repeater, and a terminal. As shown in FIG. 1 , the spatial multiplexing apparatus 100 may include a control unit 110 , a beamforming unit 120 , a multipolarization combining unit 130 , and an RF chain 140 . In addition, the RF chain 140 may be configured to include an RF block (not shown) and an orthogonal polarization antenna module. The RF block (not shown) may include a digital to analog converter (DAC)/analog to digital converter (ADC), a filter, a mixer, and the like.

The beamforming unit 120 , the multipolarization combining unit 130 , and the RF chain 140 may be more than the number shown in FIG. 1 . For example, in the case of implementing spatial multiplexing using a larger number of beam patterns (beams), the beamformer 120 , the multipolarization synthesizer 130 , and the RF chain 140 include the number shown in FIG. 1 . As described above, it may be included in the spatial multiplexing apparatus 100 .

The controller 110 may set or determine the phase and polarization of beams to be radiated through the RF chain 140 .

The controller 110 may set or determine the phases of each of the beams differently. For example, when the number of beams to be used for spatial multiplexing is n (n is a natural number equal to or greater than 2), the controller 110 may determine the phases of each of the n beams differently. The phase determined by the controller 110 may be used by the beamformer 120 to form a beam.

Also, the controller 110 may determine different polarizations (heteropolarizations) for beams adjacent to each other in space (neighboring to each other) among the plurality of beams. For example, when the number of beams to be used for spatial multiplexing is n (n is a natural number greater than or equal to 2), the controller 110 may set or determine the polarizations of the k-th beam and the l-th beam that are adjacent to each other differently.

The beamformer 120 may precode the baseband signal or data (S240).

The beamformer 120 may generate a beam determined by the controller 110 by applying a weight vector to the baseband signal (beamforming). Since the beamformer 120 precodes the signals so that each of the beams has a phase determined by the controller 110 , the beams may have different phases by the operation of the beamformer 120 .

The multi-polarization synthesizer 130 may convert the polarization of the precoded signal (S250).

The multi-polarization synthesizer 130 converts the polarization of the precoded signal through a transformation process (synthesis or decomposition) described later so that neighboring beams in space have different polarizations (polarization determined by the controller). have.

Meanwhile, the baseband signal corresponding to the processing target may be subjected to a scrambling process ( S210 ), a modulation process ( S220 ), a layer mapping process ( S230 ), and the like before being processed by the beamformer 120 .

The scrambling process ( S210 ) corresponds to a process of encrypting a baseband signal using a scrambling signal to distinguish a base station or user equipment (UE). The spatial multiplexing apparatus 100 may further include a scrambling module (not shown) for performing the scrambling process ( S210 ).

The modulation process ( S220 ) corresponds to a process of modulating the scrambled signals into a plurality of modulation (modulation) symbols. The spatial multiplexing apparatus 100 may be configured to further include a modulation module or a modulation mapper (not shown) that performs the modulation process ( S220 ).

In step S210, the scrambled signal is input to a modulation mapper (not shown) to perform binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), or 16QAM/64QAM (quadrature amplitude modulation) depending on the type and/or channel state of the signal. method can be modulated.

The layer mapping process ( S230 ) corresponds to a process of mapping modulation symbols to one or more transport layers in order to separate signals for each antenna. The spatial multiplexing apparatus 100 may further include a layer mapper (not shown) that performs the layer mapping process ( S220 ).

The spatial multiplexing apparatus 100 may further perform a process (S260) of mapping the modulation symbols obtained through the modulation process (S220) to resource elements (mapped to a frequency). To this end, the spatial multiplexing apparatus 100 may be configured to further include a resource element mapping unit (not shown), and the process of mapping to the resource element ( S260 ) may be performed by the resource element mapping unit (not shown). .

The spatial multiplexing apparatus 100 may perform an inverse fast Fourier transform (IFFT) operation to generate time-domain symbols on the polarization-transformed signals. Also, the spatial multiplexing apparatus 100 may insert a guard interval to prevent inter symbol interference (ISI) (S270). To this end, the spatial multiplexing apparatus 100 may further include an IFFT unit (not shown) and a cyclic prefix (CP).

Signals that have passed through steps S210 to S270 may be radiated in the form of a beam through the RF chain 140 . As described above, beams emitted by the spatial multiplexing method of the present invention may have different phases in space, and two neighboring beams among beams of different phases may have different polarizations.

An example of beams emitted by the spatial multiplexing method of the present invention is shown in FIG. 3 . In Fig. 3, solid-line beams (beam #1, beam #3, beam #5, and beam #7) have a polarization direction (orthogonal cross-polarization) of ±45, and dotted-line beams (beam #2, beam #4, Beam #6 and beam #8 have a polarization direction (orthogonal vertical/horizontal polarization) of V/H (vertical/horizontal).

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

That is, in the present invention, a correlation coefficient between adjacent beams can be lowered by using different polarizations (heteropolarizations) rather than using the same type of polarization between adjacent beams. In addition, any kind of polarization orthogonal to each other, such as left circular polarization/right circular polarization, may be used as heteropolarization for different polarizations.

Since beam #1 with orthogonal cross polarization (±45) and beam #2 with vertical/horizontal polarization (V/H) have different polarizations, the correlation between beam #1 and beam #2 can be small enough. have. In addition, since the beam #1 and the beam #3 having the orthogonal cross polarization (±45) are sufficiently far apart, the correlation between the beam #1 and the beam #3 may be sufficiently small.

Depending on the embodiment, the order of the process of converting the polarization of the signal ( S250 ) and the process of mapping to the resource element ( S260 ) may be changed. For example, 1) the process of converting the polarization of the signal (S250) may be performed first, the process of mapping to the resource element (S260) may be performed later, and 2) the process of mapping to the resource element (S260) is performed first and the process of converting the polarization of the signal (S250) may be performed later.

In case 1), the multipolarization synthesizer 130 converts the polarization of the precoded signal into a heteropolarization, and the resource element mapping unit (not shown) may map the polarization converted signal to the resource element. In the case of 2), the resource element mapping unit (not shown) maps the precoded signal to the resource element, and the multipolarization synthesizer 130 may convert the polarization of the signal mapped to the resource element into a heteropolarized wave. .

Hereinafter, a spatial multiplexing method using two beams (a first beam and a second beam) will be described with reference to FIG. 4 . The first beam and the second beam have different phases in space (first beam: first phase, second beam (second phase), are adjacent to each other, and have different polarizations (first beam: ±45 degrees, second beam) It is assumed to have two beams: V/H).

When the first beam and the second beam are to be radiated through the RF chain 140 , the controller 110 may determine the phases of the first beam and the second beam differently from each other, and the polarization of the first beam and the second beam can be determined differently.

The beamformer 120 may apply a weight vector to the baseband signal so that each of the first beam and the second beam has a phase determined by the controller 110 .

For example, beamforming unit #1-1 (BF #1-1, 122-1), beamforming unit #1-2 (BF #1-2. 122-2), beamforming unit #1-3 ( BF #1-3, 122-3) and the beamforming unit #1-4 (BF #1-4, 122-4) set the phase of the signal to the first phase, PD #1-1, 132-1) can be output. In addition, beamforming unit #1-1 (BF #1-1, 122-1), beamforming unit #1-2 (BF #1-2. 122-2), beamforming unit #1-3 (BF # 1-3, 122-3) and the beamforming unit #1-4 (BF #1-4, 122-4) set the phase of the signal to the second phase, and the multipolarization synthesis unit #1-2 (PD # 1-2, 132-2) can be printed.

The multipolarization synthesizer 130 may convert the polarization of the precoded signal so that each of the first beam and the second beam has a polarization (heteropolarization) determined by the controller 110 .

For example, the multi-polarization synthesis unit #1-1 (132-1) converts the polarization of the signal set as the first phase to ±45 degrees, and the multi-polarization synthesis unit #1-2 (132-2) converts the second phase into the second phase. It is possible to convert the polarization of the signal set to V/H.

A signal having (set) the first phase and a polarization of ±45 degrees may be radiated as a first beam through RF chain #1-1 (142-1) and RF chain #1-2 (142-2), A signal having (set) a polarization of 2 phase and V/H may be radiated as a second beam through RF chain #1-3 (142-3) and RF chain #1-4 (142-4).

With respect to the orthogonal polarization antenna module included in the RF chain 140 , in this specification, antenna modules arranged at +45 degrees and -45 degrees are represented. However, if the antennas are arranged in a form orthogonal to each other, various types of antenna modules such as orthogonal polarization antenna modules arranged in V (vertical) and H (horizontal) may be utilized in the present invention.

In the above, a spatial multiplexing method for a transmission signal has been described. The spatial multiplexing method for the received signal may be implemented in the reverse order of the spatial multiplexing method for the transmitted signal.

Hereinafter, a polarization conversion method of the present invention will be described with reference to FIG. 5 .

As described above, the multipolarization synthesizer 130 may convert the polarization of the precoded signal into a heteropolarization. Here, the heterogeneous polarization may include orthogonal cross polarization (±45) and orthogonal vertical/horizontal polarization (V/H).

The process of converting the polarization of a signal into a heteropolarization may be implemented through Equation 1 below.

는 PD(polarization decomposition) 행렬을 나타낸다.In Equation 1 above, a and b represent either orthogonal cross polarization (±45) and orthogonal vertical/horizontal polarization (V/H), and a+b and a+be ^jπ are orthogonal cross polarization (±45) and represents the other of orthogonal vertical/horizontal polarization (V/H),

denotes a polarization decomposition (PD) matrix.

For example, applying the PD matrix to +45 degree polarization (a) and -45 degree polarization (b), +45 degree polarization (a) and -45 degree polarization (b), and vertical polarization (a+b) and horizontal polarization (a+be ^jπ ), that is, it may be converted into a heterogeneous polarization wave.

Although it is described in FIG. 2 that steps S210 to S270 are sequentially executed, this is merely illustrative of the technical idea of an embodiment of the present invention. In other words, one of ordinary skill in the art to which an embodiment of the present invention pertains may change the order described in FIG. Since the above process may be variously modified and modified to be applied in parallel, FIG. 2 is not limited to a time-series order.

Meanwhile, the processes shown in FIG. 2 can be implemented as computer-readable codes on a computer-readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data readable by a computer system is stored. That is, the computer-readable recording medium includes a magnetic storage medium (eg, a ROM, a floppy disk, a hard disk, etc.), an optically readable medium (eg, a CD-ROM, a DVD, etc.) and a carrier wave (eg, the Internet). storage media such as transmission via In addition, the computer-readable recording medium is distributed in a network-connected computer system so that the computer-readable code can be stored and executed in a distributed manner.

The above description is merely illustrative of the technical idea of this embodiment, and various modifications and variations will be possible by those skilled in the art to which this embodiment belongs without departing from the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain rather than limit the technical spirit of the present embodiment, and the scope of the technical spirit of the present embodiment is not limited by these embodiments. The protection scope of this embodiment should be interpreted by the following claims, and all technical ideas within the equivalent range should be interpreted as being included in the scope of the present embodiment.

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Claims (10)

As a spatial multiplexing method using polarization in a multi-beam system,
determining different phases for the plurality of beams so that the plurality of beams are adjacent to each other, and determining different polarizations for the adjacent beams;
precoding a signal so that each of the plurality of beams has the determined different phases; and
and transforming the polarization of the precoded signal so that the adjacent beams have the determined different polarizations. According to claim 1,
Further comprising the step of mapping the precoded signal to a resource element,
The converting step is
A spatial multiplexing method for transforming a polarization of a signal mapped to the resource element. According to claim 1,
The spatial multiplexing method further comprising the step of mapping the polarization-converted signal to a resource element. According to claim 1,
The converting step is
A spatial multiplexing method for converting the polarization of the precoded signal into orthogonal cross polarization (±45 degrees) and orthogonal vertical/horizontal polarization. 5. The method of claim 4,
The converting step is
A spatial multiplexing method for converting the polarization of the precoded signal into the orthogonal cross polarization (±45 degrees) and the orthogonal vertical/horizontal polarization using the following equation.

In the above equation, a and b represent any one of the orthogonal cross polarization (±45 degrees) and the orthogonal vertical/horizontal polarization, and a+b and a+be ^jπ are the orthogonal vertical/horizontal polarizations (±45 degrees) and the orthogonal vertical/horizontal polarization. A spatial multiplexing device using polarization in a multi-beam system, comprising:
a control unit that determines different phases for the plurality of beams so that the plurality of beams are adjacent to each other, and determines different polarizations with respect to the adjacent beams;
a beamformer for precoding a signal so that each of the plurality of beams has the determined different phases; and
and a multi-polarization synthesizing unit configured to convert the polarization of the precoded signal so that the adjacent beams have the determined different polarizations. 7. The method of claim 6,
Further comprising a resource element mapping unit for mapping the precoded signal to the resource element,
The multi-polarization synthesizing unit,
A spatial multiplexing apparatus for transforming a polarization of a signal mapped to the resource element. 7. The method of claim 6,
The spatial multiplexing apparatus further comprising a resource element mapping unit for mapping the polarization-converted signal to a resource element. 7. The method of claim 6,
The multi-polarization synthesizing unit,
A spatial multiplexing apparatus for converting the polarization of the precoded signal into orthogonal cross polarization (±45 degrees) and orthogonal vertical/horizontal polarization. 10. The method of claim 9,
The multi-polarization synthesizing unit,
A spatial multiplexing apparatus for converting the polarization of the precoded signal into the orthogonal cross polarization (±45 degrees) and the orthogonal vertical/horizontal polarization using the following equation.

In the above equation, a and b represent any one of the orthogonal cross polarization (±45 degrees) and the orthogonal vertical/horizontal polarization, and a+b and a+be ^jπ are the orthogonal vertical/horizontal polarizations (±45 degrees) and the orthogonal vertical/horizontal polarization.

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