KR20210119824A - Method and apparatus for verification of line-of-sight signal in communication system - Google Patents

Abstract

A line-of-sight (LOS) signal verifying method in a communication system and a device thereof are disclosed. According to an embodiment of the present invention, the LOS signal verifying method performed by a terminal of a communication system comprises the following steps of: receiving a signal transmitted from a base station through a vertically polarized antenna; receiving the signal transmitted from the base station through a horizontally polarized antenna; identifying a cross polarization component between signals received through the vertically and horizontally polarized antennas based on polarization information of signals received through the vertically and horizontally polarized antennas; and determining whether a LOS environment exists based on a generation degree of the cross polarization component, thereby increasing performance of the communication system.

Description

Method and apparatus for verifying line-of-sight signals in communication systems

The present invention relates to a line-of-sight (LOS) signal verification method and apparatus in a wireless communication system, and more particularly, to a synchronization signal transmitted by a base station to a terminal in a wireless communication system through a double polarized antenna It relates to a method and apparatus for performing verification of LOS environment by transmitting and receiving.

With the development of information and communication technology, various wireless communication technologies are being developed. Representative wireless communication technologies include long term evolution (LTE) and new radio (NR) defined in 3rd generation partnership project (3GPP) standards. LTE may be one of 4G (4th Generation) wireless communication technologies, and NR may be one of 5G (5th Generation) wireless communication technologies.

4G communication system as well as a frequency band of a 4G communication system (eg, a frequency band of 6 GHz or less) for processing of wireless data that increases rapidly after commercialization of a 4G communication system (eg, a communication system supporting LTE) A 5G communication system (eg, a communication system supporting NR) that can use a higher frequency band than the frequency band (eg, a frequency band of 6 GHz or higher) is being considered. 5G communication systems can support a wide range of wireless communication scenarios, from sub-1 GHz bands for large-capacity cells to mm-wave (~52.6 GHz) for broad bandwidth (eg, 400 MHz) allocation.

In a channel environment of a high frequency band such as mm-wave, signal attenuation is greater than in a low frequency band, and path loss may be large due to diffraction, transmission, or the like. Therefore, it may be required to apply a beam forming technology for precisely transmitting a signal from the base station to the terminal direction. For communication between the base station and the terminal through beamforming, an accurate beamforming direction must be set, and the base station and the terminal must be located on a line-of-sight (LOS). In this way, the case where the base station and the terminal are located on the line of sight may be referred to as a 'LOS environment', and otherwise may be referred to as a 'non line-of-sight (NLOS) environment'. In order to smoothly perform communication between a base station and a terminal through beamforming, a technique for efficiently checking whether a communication environment is a LOS environment or an NLOS environment may be required.

It is an object of the present invention to achieve the above request, by transmitting and receiving a synchronization signal transmitted by a base station to a terminal in a wireless communication system through a double polarized antenna, verification of LOS environment in the terminal or confirmation of location information, etc. to provide a way.

A line-of-sight (LOS) signal verification method performed by a terminal of a communication system according to an embodiment of the present invention for achieving the above object is a method for receiving a signal transmitted from a base station through a vertically polarized antenna. Step, receiving a signal transmitted from the base station through a horizontally polarized antenna, based on the polarization information of the signal received through the vertical and horizontally polarized antenna, cross polarization between the signal received through the vertical and horizontally polarized antenna It may include identifying the component, and determining whether the LOS environment is present based on the generation degree of the cross polarization component.

In an embodiment of the present invention, a transmitting node may complex a signal transmitted to a receiving node into a complex number form on a complex plane and transmit it through vertical and horizontal polarized antennas. The receiving node may receive the signal transmitted from the transmitting node through vertical and horizontally polarized antennas. Through transmission and reception of vertically and horizontally polarized signals, determination of whether or not a line-of-sight (LOS) environment is present can be easily performed.

In an embodiment of the present invention, a transmitting node may complex a signal transmitted to a receiving node in a quaternary form and transmit it through vertical and horizontal polarized antennas. The receiving node may receive the signal transmitted from the transmitting node through vertical and horizontally polarized antennas. Through the transmission and reception of the complex-signaled signal in the form of a quaternion, determination of whether the LOS environment exists and delivery of location information can be easily performed.

1 is a conceptual diagram illustrating an embodiment of a communication system.
2 is a block diagram illustrating an embodiment of a communication node constituting a communication system.
3 is a conceptual diagram illustrating an embodiment of a communication system that performs beamforming using multiple antennas.
4 is a conceptual diagram for explaining an embodiment of a method of transmitting and receiving a signal through a double polarized antenna.
5 is a flowchart for explaining an embodiment of a communication system for transmitting and receiving a signal through a double polarized antenna according to the present invention.
6 is a conceptual diagram for explaining a method for transmitting and receiving a synchronization signal through a double polarized antenna according to the first embodiment of the present invention.
7 is a conceptual diagram for explaining a method of transmitting and receiving a signal through a double polarized antenna according to a second embodiment of the present invention.
8 is a conceptual diagram for explaining an embodiment of a method of expressing location information through an Euler angle according to a second embodiment of the present invention.
9 is a conceptual diagram for explaining a method of transmitting and receiving a line-of-sight (LOS) signal through a double polarized antenna according to a second embodiment of the present invention.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being “connected” or “connected” to another component, it is understood that the other component may be directly connected or connected to the other component, but other components may exist in between. it should be On the other hand, when it is mentioned that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

A communication system to which embodiments according to the present invention are applied will be described. The communication system to which the embodiments according to the present invention are applied is not limited to the contents described below, and the embodiments according to the present invention can be applied to various communication systems. Here, a communication system may be used in the same sense as a communication network (network).

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate the overall understanding, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

1 is a conceptual diagram illustrating an embodiment of a communication system.

1, the communication system 100 is a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). In addition, the communication system 100 is a core network (core network) (eg, S-GW (serving-gateway), P-GW (packet data network (PDN)-gateway), MME (mobility management entity)) may include more.

The plurality of communication nodes may support 4G communication (eg, long term evolution (LTE), advanced (LTE-A)), 5G communication, etc. defined in a 3rd generation partnership project (3GPP) standard. 4G communication may be performed in a frequency band of 6 GHz or less, and 5G communication may be performed in a frequency band of 6 GHz or more as well as a frequency band of 6 GHz or less. For example, a plurality of communication nodes for 4G communication and 5G communication is a CDMA (code division multiple access) based communication protocol, WCDMA (wideband CDMA) based communication protocol, TDMA (time division multiple access) based communication protocol, FDMA (frequency division multiple access) based communication protocol, OFDM (orthogonal frequency division multiplexing) based communication protocol, Filtered OFDM based communication protocol, CP (cyclic prefix)-OFDM based communication protocol, DFT-s-OFDM (discrete) Fourier transform-spread-OFDM) based communication protocol, OFDMA (orthogonal frequency division multiple access) based communication protocol, SC (single carrier)-FDMA based communication protocol, NOMA (Non-orthogonal multiple access), GFDM (generalized frequency) Division multiplexing)-based communication protocol, FBMC (filter bank multi-carrier)-based communication protocol, UFMC (universal filtered multi-carrier)-based communication protocol, SDMA (Space Division Multiple Access)-based communication protocol, etc. can be supported. . Each of the plurality of communication nodes may have the following structure.

2 is a block diagram illustrating an embodiment of a communication node constituting a communication system.

Referring to FIG. 2 , the communication node 200 may include at least one processor 210 , a memory 220 , and a transceiver 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240 , an output interface device 250 , a storage device 260 , and the like. Each component included in the communication node 200 may be connected by a bus 270 to communicate with each other.

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260 . The processor 210 may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may be configured as at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may be configured as at least one of a read only memory (ROM) and a random access memory (RAM).

Referring back to FIG. 1 , the communication system 100 includes a plurality of base stations 110 - 1 , 110 - 2 , 110 - 3 , 120 - 1 and 120 - 2 , and a plurality of terminals 130 - 1, 130-2, 130-3, 130-4, 130-5, 130-6). base station (110-1, 110-2, 110-3, 120-1, 120-2) and terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) The comprising communication system 100 may be referred to as an “access network”. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong to the cell coverage of the third base station 110-3. have. The first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 is a NodeB, an evolved NodeB, gNB, ng-eNB, and BTS. (base transceiver station), radio base station (radio base station), radio transceiver (radio transceiver), access point (access point), access node (node), RSU (road side unit), RRH (radio remote head), TP ( It may be referred to as a transmission point), a transmission and reception point (TRP), a flexible (f)-TRP, and the like. Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 is a user equipment (UE), a terminal, an access terminal, and a mobile Terminal (mobile terminal), station (station), subscriber station (subscriber station), mobile station (mobile station), portable subscriber station (portable subscriber station), node (node), device (device), Internet of things (IoT) It may be referred to as a device supporting a function, a mounted module/device/terminal, an on board unit (OBU), or the like.

Meanwhile, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands or may operate in the same frequency band. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other through an ideal backhaul link or a non-ideal backhaul link. , information can be exchanged with each other through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to the core network through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits a signal received from the core network to the corresponding terminals 130-1, 130-2, 130-3, 130 -4, 130-5, 130-6), and the signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) is transmitted to the core network can be sent to

In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits MIMO (eg, single user (SU)-MIMO, multi user (MU)- MIMO, massive MIMO, etc.), CoMP (coordinated multipoint) transmission, CA (carrier aggregation) transmission, transmission in an unlicensed band, direct communication between terminals (device to device communication, D2D) (or ProSe ( proximity services)), and the like. Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 is the base station 110-1, 110-2, 110-3, and 120-1. , 120-2) and corresponding operations, and operations supported by the base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be performed. For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 based on the SU-MIMO method, and the fourth terminal 130-4 may transmit a signal based on the SU-MIMO method. A signal may be received from the second base station 110 - 2 . Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO scheme, and the fourth terminal 130-4. and each of the fifth terminals 130 - 5 may receive a signal from the second base station 110 - 2 by the MU-MIMO method.

Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may transmit a signal to the fourth terminal 130-4 based on the CoMP scheme, and the fourth The terminal 130-4 may receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 by the CoMP method. A plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) each of the terminals (130-1, 130-2, 130-3, 130-4) belonging to its own cell coverage , 130-5, 130-6) and the CA method can transmit and receive signals. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 controls D2D between the fourth terminal 130-4 and the fifth terminal 130-5. and each of the fourth terminal 130-4 and the fifth terminal 130-5 may perform D2D under the control of the second base station 110-2 and the third base station 110-3, respectively. .

Meanwhile, in a communication system, a base station may perform all functions of a communication protocol (eg, a remote radio transmission/reception function, a baseband processing function). Alternatively, a remote radio transmission/reception function among all functions of a communication protocol may be performed by a transmission reception point (TRP) (eg, f(flexible)-TRP), and a baseband processing function among all functions of a communication protocol may be performed by a baseband unit (BBU) block. The TRP may be a remote radio head (RRH), a radio unit (RU), or a transmission point (TP). The BBU block may include at least one BBU or at least one digital unit (DU). A BBU block may be referred to as a “BBU pool”, a “centralized BBU”, or the like. The TRP may be connected to the BBU block through a wired fronthaul link or a wireless fronthaul link. A communication system composed of a backhaul link and a fronthaul link may be as follows. When the function split technique of the communication protocol is applied, the TRP may selectively perform some functions of the BBU or some functions of the MAC/RLC.

3 is a conceptual diagram illustrating an embodiment of a communication system that performs beamforming using multiple antennas.

In order to perform beamforming using multiple antennas, a base station of a communication system may periodically transmit synchronization signals in different directions. The synchronization signal transmitted from the base station may be a synchronization signal/physical broadcast channel (SS/PBCH) block. FIG. 3 shows an embodiment in which a base station transmits an SS/PBCH block in eight directions in order to perform beamforming using multiple antennas.

Referring to FIG. 3 , the base station may sequentially transmit eight SS/PBCH blocks (SS/PBCH blocks 0 to 7) according to a preset period. In one embodiment, the period for transmitting 8 SS/PBCH blocks in the base station may be set to 20 ms. In an embodiment, the time for transmitting each SS/PBCH block in the base station may be set to a value less than 5 ms. The UE may initially access the cell by receiving one of eight SS/PBCH blocks transmitted from the base station. The UE obtains a cell identifier (cell ID) through the received synchronization signal (SS) of the SS/PBCH block, and demodulates a physical broadcast channel (PBCH) to obtain information about frames, slots, symbols, and the like.

A communication direction between the base station and the terminal may be determined according to which SS/PBCH block the terminal has received from the base station. For example, the UE may receive the SS/PBCH block 2 by being located in the direction (beam 2) in which the SS/PBCH block 2 is transmitted among 8 SS/PBCH blocks transmitted from the base station. The UE may report to the base station that the SS/PBCH block 2 has been received. Accordingly, the base station may attempt or perform communication with the terminal toward the beam 2.

4 is a conceptual diagram for explaining an embodiment of a method of transmitting and receiving a signal through a double polarized antenna.

Referring to FIG. 4 , the communication system 400 may include a transmitting node 410 and a receiving node 420 . The transmitting node 410 may be a base station, and the receiving node 420 may be a terminal, but is not limited thereto. In an embodiment, the transmitting node 410 may transmit a signal using dual-polarized antennas 411 and 412 configured with two polarized antennas. Among the dual polarized antennas of the transmitting node 410 , the first transmit antenna 411 may be used to transmit a vertically polarized signal, and the second transmit antenna 412 transmits a horizontally polarized signal. can be used to

In an embodiment, the receiving node 420 may receive a signal using dual polarized antennas 421 and 422 configured with two polarized antennas. Among the dual polarized antennas of the receiving node 420 , a first receiving antenna 421 may be used to receive a vertically polarized signal, and a second receiving antenna 422 may be used to receive a horizontally polarized signal. In another embodiment, the receiving node 420 includes one or more receiving antennas capable of separately receiving the vertical and horizontal components of the radio signal, i.e., capable of functioning as both vertical and horizontally polarized antennas, so that the vertical and horizontal A horizontally polarized signal can be received.

A vertically polarized signal and a vertically polarized signal are very unlikely to cause fading due to mutual cancellation or interference. In other words, the vertically polarized signal and the vertically polarized signal have very low mutual fading correlation characteristics. In an ideal case, a signal transmitted through a vertically polarized antenna can be expected to be received through a vertically polarized antenna, and a signal transmitted through a horizontally polarized antenna can be expected to be received through a horizontally polarized antenna. This may be referred to as a 'direct link'. Meanwhile, due to interference or reflection on a communication path, a signal transmitted through the vertically polarized antenna may be received through the horizontally polarized antenna, and a signal transmitted through the horizontally polarized antenna may be received through the vertically polarized antenna. This may be referred to as a 'cross link'. Alternatively, the received component in this way may be referred to as a 'cross polarized component'.

Vertically and horizontally polarized signals can reduce the probability of cross polarization components due to multiple reflections on the communication path. If the receiving node 420 receives the vertically polarized signal and the horizontally polarized signal transmitted from the transmitting node 410 and a significant degree of cross polarization is confirmed, on the path between the transmitting node 410 and the receiving node 420 It may mean that there is a significant degree of interference in the This may mean that the communication environment between the two nodes is a non line-of-sight (NLOS) environment. That is, since the transmitting node 410 and the receiving node 420 transmit/receive signals through vertical and horizontal polarization processing, it can be easily determined whether the communication environment between the two nodes is the LOS environment or the NLOS environment.

) 형태로 표현할 경우, 송신 노드(410)에서 송신하는 송신 신호

는 수학식 1과 같이 표현될 수 있다.The transmitting node 410 may convert a signal to be transmitted to the receiving node 420 into a complex signal and transmit it. A transmission/reception signal and a radio channel between the transmitting node 410 and the receiving node 420 are expressed as a complex number (

) in the form of a transmission signal transmitted from the transmission node 410

can be expressed as in Equation 1.

는 수학식 2와 같이 표현될 수 있다.Then, the reception signal received by the reception node 420

can be expressed as Equation (2).

는 수학식 3과 같이 표현될 수 있다.In addition, a radio channel between the transmitting node 410 and the receiving node 420 .

can be expressed as Equation (3).

는 송신 신호

와 무선 채널

의 곱으로 나타낼 수 있다. 이를테면, 수신 신호

는 수학식 4와 같이 표현될 수 있다.receive signal

is the transmit signal

with wireless channels

can be expressed as the product of For example, the received signal

can be expressed as Equation (4).

의 실수 성분

은

로 표현될 수 있고, 허수 성분

는

로 표현될 수 있다. That is, the received signal

real component of

silver

can be expressed as , and an imaginary component

Is

can be expressed as

및

는 각각 수직 및 수평 편광 안테나인 제1 및 제2 송신 안테나(411, 412)를 통해 수직 및 수평 편광 신호로서 송신될 수 있다. 한편, 각각 수직 및 수평 편광 안테나인 제1 및 제2 수신 안테나(421, 422)를 통해 수신된 수직 및 수평 편광 신호는

및

로 표현될 수 있다. 이상적인 경우, 수직 편광 안테나를 통해 송신된 신호(

)는 수직 편광 안테나를 통해 수신되고(

), 수평 편광 안테나를 통해 송신된 신호(

)는 수평 편광 안테나를 통해 수신될(

) 것으로 기대할 수 있다. 한편, 통신 경로 상에서의 방해 또는 반사 등으로 인하여, 교차 편광 성분이 일부 수신될 수 있다. 즉, 수학식 4를 통해 도출된

에서

는 교차 편광 성분에 해당하는 것으로 볼 수 있다. 또한, 수학식 4를 통해 도출된

에서

은 교차 편광 성분에 해당하는 것으로 볼 수 있다. 따라서, 송신 노드(410)와 수신 노드(420) 간의 무선 채널

에서

은 직접 링크(direct link)와 관련된 성분(

)으로 볼 수 있고,

는 교차 링크(cross link)와 관련된 성분(

)으로 볼 수 있다. 이를 행렬로 표현하면 수학식 5와 같이 나타낼 수 있다.When the transmitting node 410 and the receiving node 420 transmit/receive a radio signal, the real component and the imaginary component may each be transmitted/received through vertical and horizontal polarized antennas. for example,

and

may be transmitted as vertically and horizontally polarized signals through the first and second transmission antennas 411 and 412 that are vertically and horizontally polarized antennas, respectively. Meanwhile, the vertically and horizontally polarized signals received through the first and second receiving antennas 421 and 422 that are vertical and horizontally polarized antennas, respectively, are

and

can be expressed as Ideally, the signal transmitted through a vertically polarized antenna (

) is received via a vertically polarized antenna (

), the signal transmitted through the horizontally polarized antenna (

) to be received via the horizontally polarized antenna (

) can be expected. On the other hand, some cross polarization components may be received due to interference or reflection on the communication path. That is, it is derived from Equation 4

at

can be regarded as corresponding to the cross polarization component. In addition, derived from Equation 4

at

can be regarded as corresponding to the cross polarization component. Accordingly, the radio channel between the transmitting node 410 and the receiving node 420 .

at

is a component associated with a direct link (

) can be seen as

is the component related to the cross link (

) can be seen as If this is expressed as a matrix, it can be expressed as in Equation 5.

The reception node 420 can easily determine whether the communication environment between the two nodes is the LOS environment or the NLOS environment by checking the ratio of the cross polarization component in the received signal. The reception node 420 may determine that the NLOS environment is present when the ratio of the cross-polarization component among the received signals is equal to or greater than the first set ratio. On the other hand, the reception node 420 may determine that the LOS environment is when the ratio of the cross polarization component among the received signals is less than the first set ratio. The first setting ratio may be applied differently depending on the nature of communication and the communication environment. For example, a higher communication quality may be required in a data communication system than in a voice communication system for a telephone or the like. Accordingly, in the data communication system, the first setting ratio may be set to a relatively low value, and in the voice communication system, the first setting ratio may be set to a relatively high value.

5 is a flowchart for explaining an embodiment of a communication system for transmitting and receiving a signal through a double polarized antenna according to the present invention.

Referring to FIG. 5 , the communication system 500 may include a transmitting node 510 and a receiving node 520 . The transmitting node 510 and the receiving node 520 may transmit/receive signals using dual-polarized antennas including at least two polarized antennas. Among the dual polarized antennas included in the transmitting node 510 , a first transmit antenna may be used to transmit a vertically polarized signal, and a second transmit antenna may be used to transmit a horizontally polarized signal. Among the dual polarized antennas included in the receiving node 520 , a first receiving antenna may be used to receive a vertically polarized signal, and a second receiving antenna may be used to receive a horizontally polarized signal.

The transmitting node 510 may transmit a signal to be transmitted to the receiving node 520 as a vertically polarized signal through the first transmitting antenna (S530). The reception node 520 may receive the vertically polarized signal propagated in the direction of the transmission node 510 through the first reception antenna ( S530 ). The transmitting node 510 may transmit a signal to be transmitted to the receiving node 520 as a horizontally polarized signal through the second transmitting antenna ( S540 ). The reception node 520 may receive the horizontally polarized signal propagated in the direction of the transmission node 510 through the second reception antenna ( S540 ).

The receiving node 520 may analyze the signal received through the vertical and horizontally polarized antennas in steps S530 and S540 (S550). The reception node 520 determines whether the communication environment between the two nodes is a line-of-sight (LOS) environment or a NLOS (non line-of-sight) environment by checking the ratio of the cross polarization component among the received signals. can be judged A method of determining whether the receiving node 520 is in an LOS/NLOS environment by checking a cross polarization component in a received signal may be the same as or similar to that described with reference to FIG. 4 .

The receiving node 520 may transmit a response to the received signal to the transmitting node 510 ( S560 ). The transmitting node 510 may receive a response transmitted from the receiving node 520 ( S560 ). A response transmitted from the receiving node 520 to the transmitting node 510 may be determined according to the type or nature of the signal received by the receiving node 520 . For example, when the ratio of the cross-polarization component in the received signal is less than the first set ratio, the reception node 520 may determine that it is a LOS environment and transmit a response reporting it to the transmission node 510 . On the other hand, when the ratio of the cross-polarization component in the received signal is equal to or greater than the first set ratio, the reception node 520 may determine that it is an NLOS environment and transmit a response reporting it to the transmission node 510 . In an embodiment, the signal transmitted from the transmitting node 510 to the receiving node 520 may be a synchronization signal such as SS/PBCH. In this case, the receiving node 520 obtains a cell identifier (PCI) included in the received synchronization signal and system information and synchronization information (frame, slot, symbol frequency, etc.) for network connection and reports it may transmit a response to the transmitting node 510 .

6 is a conceptual diagram for explaining a method for transmitting and receiving a synchronization signal through a double polarized antenna according to the first embodiment of the present invention.

In order to perform beamforming using multiple antennas, the base station may periodically transmit synchronization signals in different directions. The synchronization signal transmitted from the base station may be an SS/PBCH block (synchronization signal/physical broadcast channel). 6 illustrates an embodiment in which the base station transmits SS/PBCH blocks in eight directions in order to perform beamforming using multiple antennas.

Referring to FIG. 6 , the base station may sequentially transmit the SS/PBCH block in eight directions according to a preset period. A period in which the base station transmits the SS/PBCH block in 8 directions may be set to 20 ms. The time for the base station to transmit the SS/PBCH block in each direction may be set to a value less than 5 ms. The base station may transmit the SS/PBCH block using a dual polarization antenna consisting of a vertically polarized antenna and a horizontally polarized antenna. The base station may transmit the SS/PBCH block as a vertically polarized signal and a horizontally polarized signal using vertical and horizontally polarized antennas. A method for the base station and the terminal to transmit/receive the SS/PBCH block using the dual polarization antenna may be the same as or similar to that described with reference to FIG. 4 .

Referring to FIG. 6 , the base station may transmit vertically and horizontally polarized signals in a plurality of directions. The base station may sequentially transmit eight SS/PBCH blocks according to a preset period. The base station may transmit the SS/PBCH block as vertically and horizontally polarized signals via the dual polarization antenna. In one embodiment, the base station is operable to alternately transmit vertically and horizontally polarized signals. Meanwhile, in an embodiment, the base station may operate to simultaneously transmit vertically and horizontally polarized signals.

Vertically and horizontally polarized signals can reduce the probability of cross polarization components due to multiple reflections on the communication path. If the terminal receives the vertically polarized signal and the horizontally polarized signal transmitted from the base station, and a significant degree of cross-polarization component is identified, it may mean that a significant degree of interference is present in the path between the base station and the terminal. This may mean that the communication environment between the two nodes is the NLOS environment. That is, it is possible to easily determine whether the communication environment between the two nodes is the LOS environment or the NLOS environment by transmitting and receiving signals between the base station and the terminal by performing vertical and horizontal polarization processing.

The communication system can easily determine whether the communication environment between the base station and the terminal is the LOS environment or the NLOS environment by checking the ratio of the cross polarization component among the signals received from the terminal. The communication system may determine that the NLOS environment is present when the ratio of the cross-polarization component among the signals received from the terminal is equal to or greater than the first set ratio. On the other hand, the communication system may determine that the LOS environment is when the ratio of the cross-polarization component among the signals received from the terminal is less than the first set ratio. The first setting ratio may be applied differently depending on the nature of communication and the communication environment. For example, a higher communication quality may be required in a data communication system than in a voice communication system for a telephone or the like. Accordingly, in the data communication system, the first setting ratio may be set to a relatively low value, and in the voice communication system, the first setting ratio may be set to a relatively high value. The terminal may transmit a response reporting whether the LOS / NLOS environment to the base station.

In one embodiment, the terminal may receive a synchronization signal from a plurality of base stations. In this case, the terminal may identify the synchronization signal having the lowest ratio of the cross-polarization component among the received synchronization signals. In the synchronization signal transmitted from the base station to the terminal, the lower the ratio of the cross polarization component, the better the communication environment between the base station and the terminal. The terminal can access the base station by transmitting a response reporting the LOS environment toward the base station that has transmitted the synchronization signal having the lowest cross polarization component ratio.

In the embodiment of the present invention as described above, the transmitting node may complex the signal to be transmitted to the receiving node in the form of a complex number on a complex plane and transmit it through vertical and horizontal polarized antennas. The receiving node may receive the signal transmitted from the transmitting node through vertical and horizontally polarized antennas. Through the transmission and reception of vertically and horizontally polarized signals, determination of whether the LOS environment is present can be easily performed.

7 is a conceptual diagram for explaining a method for transmitting and receiving a signal through a double polarized antenna according to a second embodiment of the present invention.

Referring to FIG. 7 , the communication system 700 may include a transmitting node 710 and a receiving node 720 . The transmitting node 710 may be a base station, and the receiving node 720 may be a terminal, but is not limited thereto. In one embodiment, the transmitting node 710 may transmit a signal using dual-polarized antennas 711 and 712 consisting of two polarized antennas. Among the dual polarized antennas of the transmitting node 710 , a first transmit antenna 711 may be used to transmit a vertically polarized signal, and a second transmit antenna 712 transmits a horizontally polarized signal. can be used to

In one embodiment, the receiving node 720 may receive a signal using dual polarized antennas 722 and 722 configured with two polarized antennas. Among the dual polarized antennas of the receiving node 720 , a first receiving antenna 721 may be used to receive a vertically polarized signal, and a second receiving antenna 722 may be used to receive a horizontally polarized signal. In another embodiment, the receiving node 720 includes one or more receiving antennas capable of separately receiving the vertical and horizontal components of the radio signal, i.e., capable of functioning as both vertically and horizontally polarized antennas, so that the vertical and horizontal A horizontally polarized signal can be received.

Vertically and horizontally polarized signals can reduce the probability of cross polarization components due to multiple reflections on the communication path. If the receiving node 720 receives the vertically polarized signal and the horizontally polarized signal transmitted from the transmitting node 710 and a significant degree of cross polarization is confirmed, on the path between the transmitting node 710 and the receiving node 720 It may mean that there is a significant degree of interference in the This may mean that the communication environment between the two nodes is the NLOS environment. That is, since the transmitting node 710 and the receiving node 720 transmit/receive signals through vertical and horizontal polarization processing, it can be easily determined whether the communication environment between the two nodes is the LOS environment or the NLOS environment.

) 형태로 표현될 수 있다. 사원수는 3차원의 값을 다루기 위하여, 복소수를 확장하여 만들어진 수 체계이다. 사원수 체계는

를 기저(basis)로 하여,

와 같은 형태로 표현될 수 있다.

,

, 및

는 복소수의 일종으로서, 수학식 6과 같은 기본 규칙을 가질 수 있다.The transmitting node 710 may convert a signal to be transmitted to the receiving node 720 into a complex signal and transmit it. The transmission and reception signals and radio channels between the transmitting node 710 and the receiving node 720 are quaternions (

) can be expressed in the form A quaternion is a number system created by extending a complex number to deal with three-dimensional values. The quaternion system is

With , as the basis,

can be expressed in the same form as

,

, and

is a kind of complex number, and may have a basic rule as in Equation (6).

They can be multiplied by each other according to the rules shown in Table 1.

,

,

)은 표 1과 같은 규칙에 따라 상호간 곱해질 수 있다.The elements underlying the quaternary system (1,

,

,

) can be multiplied with each other according to the rules shown in Table 1.

성분을 제1 성분으로,

성분과

성분을 제2 성분으로 묶어서 칭할 수 있다. 이와 같은 방법으로, 송신 노드(710)에서 송신하는 송신 신호

는 수학식 7과 같이 표현될 수 있다.The quaternion has four components, and two components among them may be grouped to be referred to as a first component and a second component. For example, the real component and

component as a first component,

ingredients and

A component may be collectively referred to as a second component. In this way, the transmission signal transmitted from the transmission node 710

can be expressed as in Equation 7.

는 수학식 8과 같이 표현될 수 있다.Then, the reception signal received by the reception node 720

can be expressed as in Equation (8).

는 수학식 9와 같이 표현될 수 있다.And, the radio channel between the transmitting node 710 and the receiving node 720

can be expressed as in Equation (9).

는 송신 신호

와 무선 채널

의 곱으로 나타낼 수 있다. 이를테면, 수신 신호

는 수학식 10과 같이 표현될 수 있다.receive signal

is the transmit signal

with wireless channels

can be expressed as the product of For example, the received signal

can be expressed as in Equation (10).

중 제1 성분

는

로 표현될 수 있고, 제2 성분

는

로 표현될 수 있다.That is, the received signal

first component in

Is

It can be expressed as, the second component

Is

can be expressed as

및

는 각각 수직 및 수평 편광 안테나인 제1 및 제2 송신 안테나(711, 712)를 통해 수직 및 수평 편광 신호로서 송신될 수 있다. 한편, 각각 수직 및 수평 편광 안테나인 제1 및 제2 수신 안테나(721, 722)를 통해 수신된 수직 및 수평 편광 신호는

및

로 표현될 수 있다. 이상적인 경우, 수직 편광 안테나를 통해 송신된 신호(

)는 수직 편광 안테나를 통해 수신되고(

), 수평 편광 안테나를 통해 송신된 신호(

)는 수평 편광 안테나를 통해 수신될(

) 것으로 기대할 수 있다. 한편, 통신 경로 상에서의 방해 또는 반사 등으로 인하여, 교차 편광 성분이 일부 수신될 수 있다. 즉, 수학식 10을 통해 도출된

에서

는 교차 편광 성분에 해당하는 것으로 볼 수 있다. 또한, 수학식 10을 통해 도출된

에서

는 교차 편광 성분에 해당하는 것으로 볼 수 있다. 따라서, 송신 노드(710)와 수신 노드(720) 간의 무선 채널

에서

는 직접 링크(direct link)와 관련된 성분(

)으로 볼 수 있고,

는 교차 링크(cross link)와 관련된 성분(

)으로 볼 수 있다. When the transmitting node 710 and the receiving node 720 transmit/receive a radio signal, the first component and the second component may be transmitted/received through vertical and horizontal polarized antennas. for example,

and

may be transmitted as vertically and horizontally polarized signals through the first and second transmission antennas 711 and 712 that are vertically and horizontally polarized antennas, respectively. Meanwhile, the vertically and horizontally polarized signals received through the first and second receiving antennas 721 and 722 that are vertical and horizontally polarized antennas, respectively, are

and

can be expressed as Ideally, the signal transmitted through a vertically polarized antenna (

) is received via a vertically polarized antenna (

), the signal transmitted through the horizontally polarized antenna (

) to be received via the horizontally polarized antenna (

) can be expected. On the other hand, some cross polarization components may be received due to interference or reflection on the communication path. That is, it is derived from Equation 10

at

can be regarded as corresponding to the cross polarization component. In addition, derived from Equation 10

at

can be regarded as corresponding to the cross polarization component. Accordingly, the radio channel between the transmitting node 710 and the receiving node 720 .

at

is the component related to the direct link (

) can be seen as

is the component related to the cross link (

) can be seen as

로 표현 될 수 있고, 수신 신호는

로 표현될 수 있고, 무선 채널은

로 표현될 수 있다. 이를 토대로, 송수신 신호와 무선 채널 간의 관계를 행렬로 표현하면 수학식 11과 같을 수 있다.Alternatively, in the second embodiment of the present invention using a quaternary system, a transmission/reception signal and a radio channel may be expressed using a complex conjugate form. the transmit signal

can be expressed as, and the received signal is

It can be expressed as , and the radio channel is

can be expressed as Based on this, if the relationship between the transmit/receive signal and the radio channel is expressed as a matrix, it can be expressed as Equation 11.

The receiving node 720 can easily determine whether the communication environment between the two nodes is the LOS environment or the NLOS environment by checking the ratio of the cross polarization component in the received signal. The reception node 720 may determine that it is an NLOS environment when the ratio of the cross-polarization component among the received signals is equal to or greater than the second set ratio. On the other hand, when the ratio of the cross polarization component among the received signals is less than the second set ratio, the reception node 720 may determine that it is a LOS environment. The second setting ratio may be applied differently depending on the nature of communication and the communication environment. For example, a higher communication quality may be required in a data communication system than in a voice communication system for a telephone or the like. Accordingly, in the data communication system, the second setting ratio may be set to a relatively low value, and in the voice communication system, the second setting ratio may be set to a relatively high value.

8 is a conceptual diagram for explaining an embodiment of a method of expressing location information through an Euler angle according to a second embodiment of the present invention.

은

(또는

)와 같이 표현될 수 있다.

는 z축을 회전축으로 하여 회전된 x-y 좌표축의 각도를 의미할 수 있다.

는 회전된 x축을 향하여 회전된 z 축의 각도를 의미할 수 있다.

는 회전된 z 축을 회전축으로 하여 회전된 x-y 좌표축의 각도를 의미할 수 있다. Euler angles are three angles for indicating the direction in which a rigid body or object is located in a three-dimensional space. Referring to FIG. 8 , the Euler angle may be obtained by translating the coordinate axes in the x, y, and z coordinate system. Euler angle

silver

(or

) can be expressed as

may mean the angle of the xy coordinate axis rotated with the z axis as the rotation axis.

may mean an angle of the z-axis rotated toward the rotated x-axis.

may mean the angle of the xy coordinate axis rotated with the rotated z axis as the rotation axis.

와 사원수

는 수학식 12와 같은 관계를 가지도록 설정될 수 있다.Both the quaternary system and the Euler angular system are systems built for dealing with values in three-dimensional space. The orientation expressed through the Euler angle can be expressed in the form of a quaternion. For example, Euler angle

and quaternion

may be set to have a relationship as in Equation 12.

Referring to the relationship between the Euler angle and the quaternion, it can be seen that a direction or a coordinate value in a three-dimensional space can be expressed in the form of a quaternion.

Referring back to FIG. 7 , in the communication system 700 according to the second embodiment of the present invention, the transmitting node 710 may complex the signal to be transmitted to the receiving node 720 and transmit it. A transmission/reception signal and a radio channel between the transmission node 710 and the reception node 720 may be expressed in a quaternary form. The transmission signal complex-signaled in the form of a quaternary may include any direction or coordinate value in a three-dimensional space as described with reference to FIG. 8 . The complex-signaled transmission signal in a quaternary form may include location information of the transmission node 710 . The receiving node 720 may obtain location information of the transmitting node 710 by receiving a signal transmitted from the transmitting node 710 . Alternatively, the receiving node 720 may obtain a relative position with the base station or direction information of the base station by receiving the signal transmitted from the transmitting node 710 . The receiving node 720 may transmit a response reporting this to the transmitting node 710 . The transmitting node 710 may obtain the location information of the receiving node 720 by checking the response transmitted from the receiving node 720 .

As described above, according to the second embodiment of the present invention, a transmitting node may complex a signal to be transmitted to a receiving node in a quaternary form and transmit it through vertical and horizontally polarized antennas. The receiving node may receive the signal transmitted from the transmitting node through vertical and horizontally polarized antennas. Through the transmission and reception of a complex signalized signal in the form of a quaternion, it is possible to determine whether the LOS environment exists and to transmit location information.

In an embodiment of a communication system, triangulation may be used to determine location information such as a direction or distance between nodes or between a base station and a terminal. In one embodiment, the terminal receives the signal transmitted from at least three or more base stations, and the angle of arrival (AOA) of the received signal, angle of departure (AOD), propagation delay time, etc. The location information may be determined through measurement or estimation. Although triangulation enables precise location calculation, there is a limitation that signals from at least three or more base stations must be received for this purpose. According to the above-described embodiment of the present invention, a receiving node (eg, a terminal) may receive a signal transmitted through a double polarized antenna after being complex-signaled in a quaternary form from a transmitting node (eg, a base station) such as a base station. Accordingly, even when a signal is received from one transmitting node (base station, etc.), it is possible to easily determine location information.

9 is a conceptual diagram illustrating a method for transmitting and receiving an LOS signal through a double polarized antenna according to a second embodiment of the present invention.

In order to perform beamforming using multiple antennas, the base station may periodically transmit a signal (hereinafter, referred to as a 'LOS signal') for determining whether an LOS environment exists and transmitting location information in different directions. The base station may transmit a synchronization signal for connection with the terminal as an LOS signal, and on the other hand, it may be a signal for normal wireless communication between the base station and the terminal, but is not limited thereto. 9 shows an embodiment in which a base station transmits an LOS signal in eight directions.

The base station may sequentially transmit the LOS signal in the direction according to a preset period. A period in which the base station transmits the LOS signal in 8 directions may be set to 20 ms. The time for the base station to transmit the LOS signal in each direction may be set to a value less than 5 ms. The base station can transmit the LOS signal using a double polarized antenna consisting of a vertically polarized antenna and a horizontally polarized antenna. The base station may transmit the LOS signal as a vertically polarized signal and a horizontally polarized signal using vertical and horizontally polarized antennas. A method for the base station and the terminal to transmit and receive LOS signals using the dual polarization antenna may be the same as or similar to that described with reference to FIG. 7 .

The base station can transmit vertically and horizontally polarized signals simultaneously. For example, in an embodiment, the base station may sequentially transmit eight LOS signals according to a preset period. The base station may transmit the LOS signal as vertically and horizontally polarized signals via the dual polarized antenna. The base station may be operable to transmit vertically and horizontally polarized signals simultaneously. Meanwhile, the base station may alternately transmit vertically and horizontally polarized signals. For example, in one embodiment, the base station may transmit LOS signals as vertically and horizontally polarized signals via dual polarized antennas. The base station may be operable to alternately transmit vertically and horizontally polarized signals.

Vertically and horizontally polarized signals can reduce the probability of cross polarization components due to multiple reflections on the communication path. If the terminal receives the vertically polarized signal and the horizontally polarized signal transmitted from the base station, and a significant degree of cross-polarization component is identified, it may mean that a significant degree of interference is present in the path between the base station and the terminal. This may mean that the communication environment between the base station and the terminal is the NLOS environment. That is, it is possible to easily determine whether the communication environment between the two nodes is the LOS environment or the NLOS environment by transmitting and receiving signals between the base station and the terminal by performing vertical and horizontal polarization processing.

The terminal can easily determine whether the communication environment between the base station and the terminal is the LOS environment or the NLOS environment by checking the ratio of the cross polarization component in the received signal. When the ratio of the cross-polarization component among the received signals is equal to or greater than the second set ratio, the terminal may determine that it is an NLOS environment. On the other hand, when the ratio of the cross-polarization component among the received signals is less than the second set ratio, the terminal may determine that it is a LOS environment. The second setting ratio may be applied differently depending on the nature of communication and the communication environment. For example, a higher communication quality may be required in a data communication system than in a voice communication system for a telephone or the like. Accordingly, in the data communication system, the second setting ratio may be set to a relatively low value, and in the voice communication system, the second setting ratio may be set to a relatively high value.

As described above, according to the second embodiment of the present invention, a transmitting node may complex a signal to be transmitted to a receiving node in a quaternary form and transmit it through vertical and horizontally polarized antennas. The receiving node may receive the signal transmitted from the transmitting node through vertical and horizontally polarized antennas. Through the transmission and reception of a complex signalized signal in the form of a quaternion, it is possible to determine whether the LOS environment exists and to transmit location information.

The methods according to the present invention may be implemented in the form of program instructions that can be executed by various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software.

Examples of computer-readable media include hardware devices specially configured to store and carry out program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as at least one software module to perform the operations of the present invention, and vice versa.

Although it has been described with reference to the above embodiments, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. will be able

Claims (1)

In the line-of-sight (LOS) signal verification method performed by a terminal of a communication system,
receiving a signal transmitted from the base station through a vertically polarized antenna;
receiving a signal transmitted from the base station through a horizontally polarized antenna;
checking a cross polarization component between signals received through the vertically and horizontally polarized antennas based on polarization information of the signals received through the vertically and horizontally polarized antennas; and
The LOS signal verification method comprising the step of determining whether the LOS environment is based on the generation degree of the cross polarization component.

Images