Patent ID: 12255702

DESCRIPTION OF EMBODIMENTS

For the description of the relay system according to one embodiment, the background of the present invention will be described first.FIG.8is a diagram illustrating an exemplified configuration of a wireless communication system10having a dynamic reflector according to a comparative example.

In the wireless communication system10, a dynamic reflector13having a plurality of reflection elements reflects and relays radio waves to establish wireless communication between a base station11and a wireless terminal12. At this time, the base station11acquires channel state information (CSI) for all of the plurality of reflection elements included in the dynamic reflector13, and adjusts a phase of a radio wave reflected by the dynamic reflector13.

Therefore, in addition to general functions that the base station includes, the base station11needs an advanced signal processing function for acquiring and processing channel state information for all of the plurality of reflection elements, and a function to notify the dynamic reflector13of information on a phase for changing reflection characteristics.

That is, in the base station11, the overhead increases for acquiring channel information, and if the number of reflection elements is large, an enormous calculation amount is needed for dynamically controlling the phase of the radio wave reflected by the dynamic reflector13.

The wireless communication system having the relay system according to one embodiment will be described hereinbelow.FIG.1is a diagram illustrating an exemplified configuration of the wireless communication system1having the relay system according to one embodiment. As shown inFIG.1, the wireless communication system1is configured such that, for example, wireless communication is established between one or more base stations2and one or more wireless terminals3via a relay system4.

The relay system4relays a signal transmitted by the base station2to each wireless terminal3by controlling a radiation unit (e.g. dynamic reflector) having, for example, a plurality of elements (e.g. reflection elements), and relays a signal transmitted by each wireless terminal3to the base station2. The wireless terminal3has a function of measuring (positioning) a position of its own station, and may transmit position information indicating such a position to the relay system4.

The relay system4detects and analyzes a physical environment (including congestion level and environmental changes) that affects radio waves such as vehicle and pedestrians moving on the radio wave propagation path, calculates an index (described later) based on the analysis result, determines a direction in which the radiation unit should form the beam, and calculates a phase of radio waves to be radiated by each element to perform dynamic control.

English Translation of

That is, the relay system4can dynamically control the radiation direction of the radio wave without using channel state information for all of the plurality of elements and without having an advanced signal processing function for processing the channel state information for all of the elements. Although the relay system4herein is exemplified with a case where the phase of the reflected radio wave is dynamically controlled, the relay system4may be constituted as a relay device which relays the radio wave by a repeater provided with a power amplifier and forming a beam when the received radio wave is re-radiated. Further, the relay system4may dynamically control the radiation direction (reflection direction or re-radiation direction) of the radio waves at an arbitrary timing.

A specific example of the relay system4will be described hereinbelow.FIG.2is a functional block diagram illustrating functions of the relay system4. As shown inFIG.2, the relay system4includes, for example, a relay unit5and a detection unit6.

The relay unit5is a relay device which includes a radiation unit50for forming a beam, and a relay control unit52for controlling the radiation unit50, and relays radio waves.

The detection unit6is a detection device that detects, for example, the physical environment (such as vehicles and pedestrians which block radio waves) on the radio wave propagation path that affects the beam formed by the radiation unit50as environmental information, and outputs the detection results to the relay control unit52. For example, the detection unit6may be a camera that captures the surrounding environment, and detects image data as environment information.

The detection unit6may be a radio wave sensor which receives and uses radio wave as environment information indicating the surrounding environment. In this case, the detection unit6detects, for example, a receiving power, an arrival time, and channel state information of the received radio wave. A timing at which the detection unit6detects the environmental information and a timing at which the environmental information is output to the relay control unit52may be set arbitrarily in advance.

In particular, the radiation unit50is a dynamic reflector including a plurality of elements500in which, for example, the plurality of elements500are arranged in an array. The element500reflects the radio wave transmitted by the base station2and the radio wave transmitted by the wireless terminal3according to the control of the relay control unit52. For example, the element500may be a so-called metamaterial, and has a characteristic of shifting the phase when the radio wave is reflected.

The element500may be a repeater which includes a power amplifier and re-radiates the received radio wave to form a beam. In other words, the radiation unit50forms a beam in a predetermined direction by radiating radio waves from each of the plurality of elements500.

The relay control unit52includes an analysis unit520, a detection position estimation unit521, an index calculation unit522, a relay position estimation unit523, a direction determination unit524, a phase calculation unit525, a phase control unit526, and a plurality of phase conversion units527.

The analysis unit520analyzes the influence of the physical environment detected by the detection unit6on radio wave (for example, the beam formed by the radiation unit50) and outputs the analysis result to the index calculation unit522.

For example, the analysis unit520analyzes the environmental information detected by the detection unit6, and estimates, for example, type, position, moving speed, moving direction, and appearance frequency in the periphery for an object that exists around.

In particular, the analysis unit520analyzes, in a case where the environmental information is image data taken by a camera, the image and determines the object (pedestrian, vehicle, etc.) included in the image. The analysis unit520also estimates the distance and position to the object determined from the image. Further, the analysis unit520estimates the moving speed and the moving direction of the object using a plurality of continuous images.

In a case where the environmental information is the information detected by a radio wave sensor, the analysis unit520estimates the type, position, moving speed, moving direction, and appearance frequency for the object based on, for example, a relationship between the environment and a behavior of the radio wave learned in advance.

The detection position estimation unit521estimates a position where the detection unit6detects the physical environment, and outputs to the index calculation unit522detection position information indicating the position where the detection unit6performs the detection. For example, the detection position estimation unit521has a sensor device (e.g. GPS, acceleration sensor, gyro sensor, magnetic force sensor, pressure sensor, etc.) and estimates the detection position information using the sensor device. Further, the detection position estimation unit521may periodically estimate the position of the detection unit6and update the detection position information.

Further, the detection position estimation unit521may estimate the position of the detection unit6when the detection unit6is installed, or alternatively, may use information (latitude, longitude, height, and relevant information) indicating the position of the detection unit6and manually input by the operator as the detection position information.

The index calculation unit522calculates an index that can be used by the direction determination unit524to determine the direction, using the detection position information output by the detection position estimation unit521and the analysis result output by the analysis unit520, and outputs the calculated index to the direction determination unit524.

For example, the index calculation unit522calculates the index that can be used by the direction determination unit524to determine the direction in which the radiation unit50reflects (or re-radiates) the beam, using the type, distance, position, moving speed and moving direction of the surrounding object, which are estimated by the analysis unit520.

The index calculated by the index calculation unit522is, for example, the density of the object estimated by the analysis unit520. For example, the index calculation unit522may estimate the number of objects existing in a predetermined area and calculate the density based on the position of the object, which has been estimated by the analysis unit520.

Further, the index calculation unit522may use a time that the object stays in the predetermined area as the index, or alternatively, may calculate an average staying time of the object for each area and use the product of the appearance frequency of the object and the average staying time as the index. The index calculation unit522may calculate and list the index for each area, and output to the English Translation of direction determination unit524the listing result by giving priority to the area having the highest index value.

The relay position estimation unit523estimates a position where the relay unit5relays the radio wave, and outputs to the direction determination unit524relay position information indicating the position where the relay unit5relays the radio wave. For example, the relay position estimation unit523has a sensor device (GPS, acceleration sensor, gyro sensor, magnetic force sensor, pressure sensor, etc.) and estimates the relay position information using the sensor device. Further, the relay position estimation unit523may periodically estimate the position of the relay unit5and update the relay position information.

The relay position estimation unit523may estimate a position of the relay unit5when the relay unit5is installed, or alternatively, may use information (latitude, longitude, height, and relevant information) indicating the position of the relay unit5and manually input by the operator as the relay position information.

In a case where the relay unit5and the detection unit6are integrally configured, assuming that the relay position information and the detection position information have the same value, it is not necessary to provide either the relay position estimation unit523or the detection position estimation unit521.

The direction determination unit524determines the direction (reflection or re-radiation direction) in which the radiation unit50should form a beam, based on the relay position information output by the relay position estimation unit523and the index (for example, a list) calculated by the index calculation unit522, and outputs direction information indicating the determined direction to the phase calculation unit525.

For example, in a case where the index calculated by the index calculation unit522is a density, the direction determination unit524determines a direction of an area having a high density as the direction of reflection or re-radiation. Further, the direction determination unit524may determine a direction toward the center of the area, or may determine a direction toward the center of gravity of the object position at a certain moment in the area.

In a case where the index calculated by the index calculation unit522is the product of the staying time or appearance frequency of the object and the average staying time, the direction determination unit524sets, for example, an area having the maximum value as the area having the highest priority, and determines the direction toward the area in the same manner.

The phase calculation unit525calculates the phase of the radio wave to be radiated by each of the plurality of elements500, and outputs phase information indicating the calculated phase to the phase control unit526, such that the radiation unit50forms a beam in the direction determined by the direction determination unit524.

For example, the phase calculation unit525calculates a phase amount to be controlled by the phase control unit526using the direction determined by the direction determination unit524and the direction toward the base station2. At this time, the phase calculation unit525may estimate the direction to the base station2using preset position information (latitude, longitude and height) of the base station2and the relay position information estimated by the relay position estimation unit523.

In a case where the detection unit6is a camera and is taking photos of the surrounding environment, the phase calculation unit525may estimate a direction from the relay unit5to the base station2using the position information of the base station2estimated by the analysis unit520with the image data as the environmental information, as well as the detected position information and the relay position information as stated above.

In a case where the single radiation unit50radiates using radio waves transmitted from the plurality of wireless terminals3, the phase calculation unit525may divide the plurality of elements500into a plurality of element groups, and calculate the phase of the radio waves radiated by each element500so as to radiate the radio waves toward the different wireless terminals3for each element group.

For example, in a case of reflecting (or re-radiating) radio waves to four high-priority areas at the same time, the relay unit5having N elements500may calculate the phase of the radio wave so as to radiate the radio wave in each direction of the area using N/4 elements500for each area. In this case, the relay unit5can improve the communication quality of the plurality of areas at the same time, although the gain after the radiation of the radio wave is reduced.

The phase control unit526controls the phase of the radio waves radiated by each of the plurality of elements500by controlling each of the plurality of phase conversion units527based on the phase information calculated by the phase calculation unit525. The phase conversion unit527is provided individually, for example, for each element500, and performs conversion that changes the phase of the radio waves radiated by the element500according to the control conducted by the phase control unit526.

For example, the phase control unit526controls each of the plurality of phase conversion units527such that the phase of the radio wave reflected by each of the plurality of elements500is slightly shifted based on the phase calculated by the phase calculation unit525. For example, in a case where the element500is the metamaterial stated above, the phase conversion unit527dynamically changes the phase shift amount allocated the element500by changing the characteristics of the element500according to the control of the phase control unit526. In this way, the phase control unit526controls the radiation unit50to perform beamforming in a predetermined direction by changing the characteristics of the metamaterial, multiplying the phase change amount, or imparting a predetermined delay.

In a case where the controllable phase amount for the element500is discrete, the phase control unit526selects the phase amount closest to the phase (phase change amount) calculated by the phase calculation unit525from the configurable phase amounts, and controls each of the plurality of phase conversion units527.

An exemplified operation of the relay system4will be described hereinbelow.FIG.3is a flowchart illustrating the exemplified operation of the relay system4. As shown inFIG.3, in the relay system4, the detection unit6first detects the surrounding physical environment as the environmental information (S100).

In the relay system4, the analysis unit520analyzes the environmental information (S102), and the detection position estimation unit521estimates the detection position of the detection unit6(S104).

The index calculation unit522calculates the index that can be used by the direction determination unit524to determine the direction using the result analyzed by the analysis unit520and the detection English Translation of position estimated by the detection position estimation unit521(S106).

When the relay position estimation unit523estimates the relay position where the relay unit5relays the radio wave (S108), the direction determination unit524determines the radiation direction in which the radiation unit50emits the beam (S110) based on the relay position information estimated by the relay position estimation unit523and the index calculated by the index calculation unit522.

The phase calculation unit525calculates the phase of the radio wave to be radiated by each of the plurality of elements500such that the radiation unit50radiates the beam in the direction determined by the direction determination unit524(S112).

The phase control unit526controls the phase of the radio waves radiated by each of the plurality of elements500by controlling each of the plurality of phase conversion units527based on the phase calculated by the phase calculation unit525(S114).

In the relay system4, the phase calculation unit525calculates the phase of the radio wave to be radiated by each of the plurality of elements500based on the physical environment detected by the detection unit6, and the phase control unit526controls the phase of the radio waves radiated by each of the plurality of elements500. Therefore, even if the physical environment on the radio wave propagation path changes, radio waves can be relayed efficiently. Further, since the relay system4controls the phase of the radio waves radiated by each of the elements500when the radio wave arrives, it is possible to expand the coverage by the base station2.

A wireless communication system including a relay system according to another embodiment will be described hereinbelow.FIG.4is a diagram illustrating an exemplified configuration of a wireless communication system1ahaving a relay system according to another embodiment. As shown inFIG.4, the wireless communication system1ais configured such that, for example, wireless communication is established between the base station2and the wireless terminal3via a relay system4a.

The relay system4ahas, for example, two detectors7-1and7-2, two relay devices8-1and8-2, and a relay control device9. Hereinafter, in a case where one of a plurality of configurations such as the detection devices7-1and7-2is not specified, it is simply abbreviated as, for example, the detection device7.

Similar to the detection unit6described above, the detection device7has a function of detecting the physical environment (such as vehicles and pedestrians which block radio waves) on the radio wave propagation path that affects radio waves as the environmental information, and a function of transmitting the detected environmental information to the relay control device9. For example, the detection device7is, for example, a camera that captures the surrounding environment, detects image data as the environment information, and transmits the image data to the relay control device9. Further, the detection device7may be a radio wave sensor that receives radio waves and uses them as the environmental information indicating the surrounding environment.

FIG.5is a functional block diagram illustrating the functions of the relay device8. As shown inFIG.5, the relay device8includes a radiation unit50that forms a beam and a control unit52athat controls the radiation unit50, and relays radio waves. For the relay device8shown inFIG.5, the functional blocks substantially the same as the functional blocks of the relay unit5shown inFIG.2are designated by the same reference numerals.

The control unit52aincludes a reception unit528, a phase control unit526, and a plurality of phase conversion units527. The reception unit528receives information transmitted by the relay control device9and outputs it to the phase control unit526.

FIG.6is a functional block diagram illustrating functions of the relay control device9. As shown inFIG.6, the relay control device9includes, for example, a reception unit90, an analysis unit520, a detection position estimation unit521, an index calculation unit522, a relay position estimation unit523, a direction determination unit524, a phase calculation unit525, and a transmission unit92. For the relay control device9shown inFIG.6, the functional blocks substantially the same as the functional blocks of the relay unit5shown inFIG.2are designated by the same reference numerals.

The reception unit90receives the environmental information transmitted by each detection device7and outputs it to the analysis unit520. The transmission unit92transmits the phase (phase amount) of the radio wave calculated by the phase calculation unit525to the relay device8corresponding to each of the detection devices7.

That is, the wireless communication system1acan reflect or re-radiate radio waves in the same manner as the wireless communication system1to enable wireless communication between the base station2and the wireless terminal3. The relay device8may be arranged near the corresponding detection device7, or may be associated with the detection device7arranged at a distant position.

Further, the relay control device9can cover an area where, for example, the relay devices8-1and8-2are the same (or partially common), and may control the relay device8having the shortest distance to the area to relay radio waves in a case where there are multiple areas with relatively high index values, or in a case where the areas with the highest priority of the relay devices8-1and8-2overlap.

Further, the relay control device9may control such that the reflection (re-radiation) direction of the relay device8having the shortest distance to the area is assigned to the area, and the other relay device8is assigned to the area having the next highest priority. The relay control device9may repeat the same process even when the areas having the next highest priority overlap. Further, the relay control device9may perform the process stated above in a case where the upper limit of the number of relay devices8that allow duplication is set in advance and the number of relay devices8exceeds the upper limit.

The functions of the relay control device9are not limited to the example shown inFIG.6. For example, the relay control device9may not have all the functions of the analysis unit520, the detection position estimation unit521, the index calculation unit522, the relay position estimation unit523, the direction determination unit524, and the phase calculation unit525. Each function of the relay control device9may be divided into a plurality of devices. A method in which the relay control device9establishes communication with the detection device7and the relay device8may be wired communication or wireless communication, respectively.

Each function of the relay control device9may be partially or wholly configured by hardware such as PLD (programmable logic Device) or FPGA (field programmable gate array), or may be configured as a program executed by a processor such as a CPU.

For example, the relay control device9according to the present English Translation of invention can be implemented using a computer and a program, and the program can be recorded on a recording medium or provided via a network.

FIG.7is a diagram illustrating an exemplified hardware configuration of the relay control device9according to one embodiment. As shown inFIG.7, for example, the relay control device9has an input unit900, an output unit910, a communication unit920, a CPU930, a memory940, and an HDD950, connected via a bus960with each other, which has a function as a computer. The relay control device9is configured to be able to input/output data to/from a computer-readable recording medium970.

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

As described above, the CPU930controls each unit constituting the relay control device9and performs, for example, predetermined processes. The memory940and the HDD950are storage units for storing data and the like.

The recording medium970is capable of storing a program for executing the functions of the relay control device9. The architecture constituting the relay control device9is not limited to the example shown inFIG.7.

It is assumed that a “computer” as used herein includes an OS and hardware such as peripheral devices. In addition, a “computer-readable recording medium” refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM.

Furthermore, a “computer-readable recording medium” may also include a computer-readable recording medium that dynamically holds a program for a short amount of 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, and a computer-readable recording medium in which a program is held for a certain amount of time, such as a volatile memory inside a computer that serves as a server or a client in such a case.

Although embodiments of the present invention were described above with reference to the drawings, it is apparent that the embodiments stated above are merely exemplary illustrations of the present invention and the present invention is not limited to those embodiments. Accordingly, additions, omissions, substitutions, and other modifications of the components may be made within a scope that does not depart from the technical spirit and scope of the present invention.

REFERENCE SIGNS LIST

1,1a: Wireless communication system2: Base station3: Wireless terminal4,4a: Relay system5: Relay unit6: Detection unit7-1,7-2: Detection device8-1,8-2: Relay device9: Relay control device50: Radiation unit52: Relay control unit52a: Control unit90: Reception unit92: Transmission unit500: Element520: Analysis unit521: Detection position estimation unit522: Index calculation unit523: Relay position estimation unit524: Direction determination unit525: Phase calculation unit526: Phase control unit527: Phase conversion unit528: Reception unit900: Input unit910: Output unit920: Communication unit930: CPU940: Memory950: HDD960: Bus970: Recording medium