Patent ID: 12244368

DESCRIPTION OF EMBODIMENTS

A background in which the present invention has been achieved will be first described in description of a reflection direction control system according to an embodiment.FIG.6is a diagram illustrating a configuration example of a wireless communication system10in a comparative example including a dynamic reflection plate.

In a wireless communication system10, a dynamic reflection plate13including a plurality of reflection elements reflects and relays radio waves in order to perform wireless communication between a base station11and a wireless terminal12. In this case, the base station11acquires channel information (CSI: Channel State Information) for all of the plurality of reflection elements included in the dynamic reflection plate13, and adjusts a phase of a radio wave reflected by the dynamic reflection plate13.

Therefore, in addition to a general base station function, the base station11needs an advanced signal processing function for acquiring and processing channel information for all of the plurality of reflection elements, and a function for notifying the dynamic reflection plate13of information on a phase for changing reflection characteristics.

That is, in the base station11, when an overhead for acquiring channel information increases and the number of reflection elements is large, an amount of calculation for dynamically controlling the phase of the radio wave reflected by the dynamic reflection plate13becomes enormous.

Next, a wireless communication system including a reflection direction control system according to an embodiment will be described.FIG.1is a diagram illustrating a configuration example of the wireless communication system1according to an embodiment of the present invention. As illustrated inFIG.1, the wireless communication system1is configured such that, for example, a base station2and one or more wireless terminals3perform wireless communication via a reflection direction control system4.

The reflection direction control system4is configured to reflect a radio wave transmitted by the wireless terminal3toward the base station2and reflect a radio wave transmitted by the base station2toward the wireless terminal3.

FIG.2is a functional block diagram illustrating functions of the reflection direction control system4according to an embodiment. As illustrated inFIG.2, the reflection direction control system4includes a reflection unit5and a reflection direction control device6.

The reflection unit5is a dynamic reflection plate (IRS: Intelligent Reflecting Surface) that includes, for example, n reflection elements50-1to50-nand, for example, the reflection elements50-1to50-n, are arranged in an array form. The reflection elements50-1to50-nreflect the radio wave transmitted by the base station2and the radio wave transmitted by the wireless terminal3according to the control of the reflection direction control device6. For example, the reflection elements50-1to50-nare of a so-called metamaterial, and a phase characteristic thereof can be dynamically changed when the radio wave is reflected.

Further, the reflection unit5may be configured to receive a radio wave having a frequency lower than a predetermined value when the switching unit664switches to an antenna mode, and reflect a radio wave having a frequency higher than the predetermined value when the switching unit664switches to a reflection mode, as will be described later.

The reflection direction control device6includes an arrival direction estimation unit60, a phase calculation unit62, a weight calculation unit64, and a reflection element control unit66, and controls an operation and function of the reflection unit5.

The arrival direction estimation unit60estimates, for example, an arrival direction of the radio wave transmitted by the wireless terminal3to the reflection unit5, and outputs arrival direction information indicating the estimated arrival direction of the radio wave to the phase calculation unit62. Specifically, when the reflection unit5receives the radio wave transmitted by the wireless terminal3in the antenna mode (to be described later), the arrival direction estimation unit60estimates the arrival direction of the radio wave transmitted by the wireless terminal3on the basis of the radio wave received by the reflection unit5.

The phase calculation unit62calculates the phase of radio waves to be reflected by each of the reflection elements50-1to50-n, for example, so that the reflection unit5reflects the radio wave transmitted toward the reflection unit5by the wireless terminal3in a predetermined direction (for example, a direction of the base station2), on the basis of the arrival direction information output by the arrival direction estimation unit60, and outputs phase information indicating the calculated phase to the weight calculation unit64.

The weight calculation unit64calculates a weight corresponding to a phase to be changed for each of the reflection elements50-1to50-n, on the basis of phase information output by the phase calculation unit62, and outputs the calculated weight to the reflection element control unit66.

The weight calculation unit64can calculate the weight so as to maximize the directivity of the reflection unit5or can calculate the weight so as to minimize (null) the directivity of the reflection unit5, on the basis of the phase information output by the phase calculation unit62, for example.

The reflection element control unit66includes a storage unit660, a phase control unit662, and a switching unit664. The storage unit660stores information such as the weight output by the weight calculation unit64, and outputs the stored information to the phase control unit662in response to access from the phase control unit662.

The phase control unit662controls the reflection elements50-1to50-nso that the phases of the radio wave to be reflected are shifted little by little on the basis of, for example, the weights stored in the storage unit660. For example, when the reflection elements50-1to50-nare the meta-material described above, the phase control unit662changes characteristics of the reflection elements50-1to50-nto dynamically change a phase shift amount, and performs control so that the reflection unit5performs beam forming in a predetermined direction.

That is, the phase control unit662controls the phase of the radio wave reflected by each of the reflection elements50-1to50-nso that the reflection unit5reflects a radio wave transmitted from the arrival direction estimated by the arrival direction estimation unit60in a predetermined direction.

The switching unit664switches between an antenna mode in which the reflection unit5is caused to receive the radio wave of which the arrival direction is estimated by the arrival direction estimation unit60and a reflection mode in which the reflection unit5is caused to reflect the radio wave under control of the phase control unit662, according to an instruction from an operator or predetermined setting.

That is, the reflection direction control system4is configured to be able to switch between an antenna mode in which the reflection unit5is used to estimate the arrival direction of the radio wave transmitted by the wireless terminal3and a reflection mode in which communication between the wireless terminal3and the base station2is relayed by reflection in the reflection unit5, for example, according to an instruction from an operator or a predetermined setting.

The radio wave received by the reflection unit5in the antenna mode may be, for example, a low-frequency test signal transmitted by the wireless terminal3or, for example, a normal high-frequency signal transmitted by the wireless terminal3.

FIG.3is a flowchart illustrating an operation example of the reflection direction control system4according to an embodiment. As illustrated inFIG.3, the reflection direction control system4determines whether or not the switching unit664performs switching to the antenna mode (S100). The reflection direction control system4proceeds to processing of S102when the reflection direction control system4determines that the switching unit664performs switching to the antenna mode (S100: Yes), and proceeds to processing of S108when the reflection direction control system4determines that the switching unit664does not perform switching to the antenna mode (S100: No).

In the reflection direction control system4, when the arrival direction estimation unit60estimates the arrival direction of the radio wave that the wireless terminal3has transmitted to the reflection unit5(S102), the phase calculation unit62calculates the phase of each of the reflection elements50-1and50-non the basis of arrival direction information (S104).

When a weight calculation unit64calculates the weights of the respective reflection elements50-1to50-non the basis of the phase information (S106), the reflection direction control system4stores the calculated weights in the storage unit660.

In the reflection direction control system4, the phase control unit662performs phase control on each of the reflection elements50-1to50-nusing the weights stored in the storage unit660, so that the reflection unit5performs beam forming in a predetermined direction (S108).

Hereinafter, a modification example of the wireless communication system1will be described.FIG.4is a diagram illustrating a configuration of the modification example (a wireless communication system1a) of the wireless communication system1. As illustrated inFIG.4, the wireless communication system1ais configured such that, for example, the base station2and one or more wireless terminals3can perform wireless communication via a plurality of reflection direction control systems4.

Further, each of the reflection direction control systems4can communicate with the relay control device7via a communication unit (not illustrated). The relay control device7controls each of the reflection direction control systems4, so that the base station2and the wireless terminal3can perform wireless communication via at least one of the reflection direction control systems4.

In the wireless communication system1a, when the respective reflection units5(FIG.2) included in the plurality of reflection direction control systems4receive the radio wave transmitted by the wireless terminal3in the antenna mode, the arrival direction estimation unit60may estimate the arrival direction of the radio wave transmitted by the wireless terminal3on the basis of the radio wave received by each of the plurality of reflection units5.

Functions of the reflection direction control device6may be included in each of the reflection direction control systems4or may be included in the relay control device7.

Thus, because the wireless communication system1and the wireless communication system1aswitch between the antenna mode in which the reflection unit5is caused to receive the radio wave of which the arrival direction is estimated by the arrival direction estimation unit60and the reflection mode in which the reflection unit5is caused to reflect the radio wave under control of the phase control unit662, it is possible to dynamically control a reflection direction of a radio wave with a small amount of calculation.

That is, the wireless communication system1and the wireless communication system1acan dynamically control the reflection direction of the radio wave even when the wireless communication system1and the wireless communication system1ado not include an advanced signal processing function for processing the channel information for all of the reflection elements, without acquiring the channel information for all of the plurality of reflection elements.

In the wireless communication system1and the wireless communication system1a, because the reflection direction control system4controls the phase of the radio wave to be reflected by each of the reflection elements50-1and50-nwhen the radio wave arrives, it is also possible to expand a coverage of the base station2.

Functions of the reflection direction control device6may be partially or entirely configured of hardware such as a programmable logic device (PLD) or a field programmable gate array (FPGA), or may be configured as a program that is executed by a processor such as a CPU.

For example, the reflection direction control device6according to the present invention can be realized using a computer and a program, and the program can be recorded on a storage medium or provided through a network.

FIG.5is a diagram illustrating an example of a hardware configuration of the reflection direction control device6according to the embodiment. As illustrated inFIG.5, for example, the reflection direction control device6includes an input unit900, an output unit910, a communication unit920, a CPU930, a memory940, and an HDD950connected via a bus960, and includes a function of a computer. The reflection direction control device6can input and output data to and from a computer-readable storage medium970.

The input unit900is, for example, a keyboard, a mouse, or a touch panel. The output unit910is, for example, a display device such as a display. The communication unit920is, for example, a wireless network interface.

The CPU930controls the respective units constituting the reflection direction control device6as described above, and performs predetermined processing or the like. The memory940and the HDD950are, for example, the above-described storage unit660that stores data or the like.

The storage medium970can store, for example, a program for executing functions of the reflection direction control device6. An architecture constituting the reflection direction control device6is not limited to the example illustrated inFIG.5. Another configuration constituting the wireless communication system1asuch as the relay control device7may be the same hardware configuration as the reflection direction control device6.

It is assumed that a “computer” as used herein includes an OS or hardware such as peripheral devices. Further, the “computer-readable storage medium” refers to a storage device such as a flexible disk, a magneto-optical disc, a ROM, or a portable medium such as a CD-ROM.

Further, the “computer-readable storage medium” may also include a recording medium that dynamically holds a program for a short time, such as a communication line used in the case of transmitting a program via a network such as the Internet or a communication line such as a telephone line, or a recording medium in which a program is held for a certain time, such as a volatile memory inside a computer that serves as a server or a client in such a case.

Although the embodiment of the present invention has been described above with reference to the drawings, it is obvious that the above-described embodiment is merely an example of the present invention and the present invention is not limited to the above-described embodiment. Accordingly, additions, omissions, substitutions, and other modifications of components may be made without departing from the technical spirit and scope of the present invention.

REFERENCE SIGNS LIST

1,1aWireless communication system2Base station3Wireless terminal4Reflection direction control system5Reflection unit6Reflection direction control device7Relay control device50-1to50-nReflection element60Arrival direction estimation unit62Phase calculation unit64Weight calculation unit66Reflection element control unit660Storage unit662Phase control unit664Switching unit900Input unit910Output unit920Communication unit930CPU940Memory950HDD960Bus970Storage medium