WO2011021321A1

WO2011021321A1 - Short-distance wireless system, short-distance wireless apparatus and short-distance wireless method

Info

Publication number: WO2011021321A1
Application number: PCT/JP2010/002784
Authority: WO
Inventors: 河田友春; 長尾彰文; 入江誠隆; 稲垣貴行
Original assignee: パナソニック株式会社
Priority date: 2009-08-18
Filing date: 2010-04-16
Publication date: 2011-02-24
Also published as: JP2011041211A

Abstract

A short-distance wireless system used between two communication devices is disclosed wherein, for example, for an indoor use, one of the two communication devices, which is to measure a distance, transmits a signal, generated by a known signal generating circuit (101), via an antenna (100), while the other of the two communication devices, the distance of which is to be measured, receives the signal via an antenna (100); subjects the received signal to a predetermined process implemented by a known signal processing circuit (105); and thereafter transmits, in return, the resultant signal to the communication device, which is to measure the distance, via the antenna (100). In the communication device that is to measure the distance, an arrival time calculating circuit (106) calculates a signal arrival time, which is a time period from a start of transmitting the transmitted signal to the reception of the transmitted signal; a distance calculating circuit then calculates, based on the arrival time, the distance between the two communication devices; and a transmission power control circuit (103) controls, based on the calculated distance, the transmission power of a signal that is to be transmitted. Thus, the measurement of the distance between two communication devices can be implemented by use of a low-cost system, and further a stable, high-speed transmission also can be achieved with a reduced power consumption.

Description

Short-range wireless system, short-range wireless device, and short-range wireless method

The present invention relates to a short-range wireless system in which two communication devices that communicate with each other perform wireless communication.

Conventionally, in a mobile phone system, a base station calculates the position of a mobile station with a certain degree of accuracy based on the arrival direction and delay time of the radio wave of the mobile station, and calculates the calculated mobile station position and cell arrangement. The cell to which the mobile station belongs is determined by referring to the associated map. Then, if the determined cell of the mobile station is different from the cell of the base station currently communicating, the communication between the mobile station and the base station is changed to the communication with the base station of the destination cell. Switching is performed to avoid degradation of call quality and call disconnection without reducing frequency use efficiency, and to perform handover without increasing the processing load on the base station and mobile station.

As described above, in the mobile phone system, as in Patent Document 1, for example, the base station has determined the position of only the mobile station, and has switched cells.

FIG. 11 shows a configuration example of wireless communication using positioning in a conventional mobile phone system. In the figure, 200 is four antennas, 201 is a data modulation circuit, 202 is a directivity control circuit, 203 is a delay time measurement circuit, 204 is an arrival direction measurement circuit, 205 is a position calculation circuit, and 206 is a data demodulation circuit. is there. In addition, the structure shown here adapts four antennas.

In FIG. 11, each base station includes an arrival direction measurement circuit 204 that measures the arrival direction of radio waves emitted from the mobile station, a delay time measurement circuit 203 that measures delay time of radio waves emitted from the mobile station, and the arrival direction measurement circuit. A position calculation circuit 205 that calculates the position of the mobile station from the arrival direction S205 measured by the delay time 204 and the delay time S204 measured by the delay time measurement circuit 203; and a directivity control circuit that controls the directivity direction of radio waves to be transmitted and received 202 and data for determining the directivity direction of the directivity control circuit 202 corresponding to the mobile station position S206 calculated by the position calculation circuit 205 and forming directivity in the direction of the mobile station to communicate with the mobile station A modulation circuit 201 and a data demodulation circuit 206 are provided, and a cell to which the mobile station belongs is determined with reference to a map in which the position of the mobile station is associated with the cell arrangement. When the determined mobile station cell is different from the cell of the base station that is currently communicating, the communication between the mobile station and the base station is switched to the communication with the base station of the destination cell. It was.

JP 2001-169325 A

By the way, recently, in the high-speed short-range wireless system of several hundreds Mbps to several Gbps by microwaves and millimeter waves, use cases such as high-speed file transfer indoors and high-speed streaming are attracting attention from the market.

In order to realize a short-range wireless system between two communication devices, particularly indoors, for example, between a mobile phone and a Blu-ray device, the power consumption of the mobile phone is reduced and stable. It is necessary to realize high-speed transmission.

However, the conventional mobile phone system using positioning uses a large-scale base station and a system such as GPS, and has poor positioning accuracy, and is intended for cell switching. . In addition, the target of positioning was only performed by the base station on the mobile station. Therefore, the conventional mobile phone system cannot be applied as it is to a short-distance wireless system such as indoors, and power consumption cannot be reduced in a mobile phone or the like.

An object of the present invention is to realize stable high-speed communication while reducing power consumption particularly in an indoor short-range wireless system.

The following are the disadvantages of a general positioning system in the conventional mobile phone system.

1. Positioning using GPS The power consumption and cost of the node are high, and the estimation accuracy is low indoors and underground where radio waves do not reach from the satellite.

2. Positioning using arrival times of radio signals to be transmitted and received Estimate the position of other nodes based on the position of some fixedly installed reference nodes. However, it is necessary to increase the time processing accuracy at the node (accuracy degradation due to temperature fluctuations in analog circuits such as LNA and MIXER).

3. Positioning using radio signal reception power Based on the position of some fixed reference nodes, the position of other nodes is estimated. However, if the distance between nodes is estimated using the property that the received power attenuates in inverse proportion to the distance (distance attenuation), it will be affected by multipath fading and will be greatly affected by the surrounding environment even at the same distance. Affected.

Also, the outline of the main technology in the conventional mobile phone system will be described as follows. One of the methods for controlling the directivity includes beam forming, beam steering, and null steering. Beam forming is a technology that makes it possible for adjacent base stations to use the same frequency band, and has the effect of significantly increasing the use efficiency of radio waves. In realizing this, radio waves fly in the direction in which the interfering station is located. Two techniques are combined: null steering, which prevents the reception of radio waves from that direction, and beam steering, which concentrates the radio waves of the base station in a specific direction. That is, it is possible to communicate with a terminal farther from the base station by beam steering while preventing interference between base stations and between the terminal and the base station by null steering.

In order to achieve the above object, according to the present invention, in a short-range wireless system, before starting communication between two communication devices, the distance between the two communication devices is measured, and the transmission signal is based on the measured value. By appropriately controlling the transmission power, it is possible to achieve both low power consumption and stable high-speed communication.

Specifically, the short-range wireless system of the present invention is a short-range wireless system that performs transmission and reception of radio waves between two communication devices at a short distance, and estimates the distance between the two communication devices. The transmission power of the radio wave is controlled in the transmission side communication device that transmits the radio wave based on the distance.

In one embodiment of the present invention, in the short-range wireless system, the two communication devices have a data communication mode in which data is wirelessly communicated between the two communication devices. The device includes an antenna for data transmission, a data modulation unit that modulates data to be transmitted in the data communication mode, and a transmission power of data modulated by the data modulation unit between the two estimated communication devices. And transmission power control means for transmitting data after the power control from the antenna.

One embodiment of the present invention is characterized in that, in the short-range wireless system, the estimation of the distance is performed based on at least one of the arrival time and the reception power of the radio wave.

In one embodiment of the present invention, in the short-range wireless system, a receiving communication device that receives the radio wave performs reception power control that controls a control gain of a reception signal that has received the radio wave from the transmitting communication device. It is characterized by that.

In one embodiment of the present invention, in the short-range wireless system, the two communication devices have a directional antenna, and estimate an angle at which the communication device on the communication partner side is located with respect to the own communication device. The directional antenna is controlled in the direction of the estimated angle.

In one embodiment of the present invention, in the short-range wireless system, the two communication devices have a distance measurement mode for measuring a distance between the two communication devices, and the distance measurement side of the two communication devices is The communication device has a known signal generation means for generating a predetermined known signal and transmitting it from the antenna in the distance measurement mode, and the communication device on the distance measuring side has the known signal in the distance measurement mode. A known signal processing means for receiving a known signal from the generating means and returning a signal based on the known signal from the antenna as a return signal; and the distance measuring side communication device further includes a distance between the two communication devices. Estimation of arrival time based on the arrival time calculated by the arrival time calculating means for calculating the arrival time from the transmission of the known signal to the arrival of the return signal from the communication device on the measured distance side. There are, characterized in that it comprises a distance calculating means for calculating the distance between the two communication devices.

In one embodiment of the present invention, in the short-range wireless system, the two communication devices have a distance measurement mode for measuring a distance between the two communication devices, and the distance measurement side of the two communication devices is The communication device has a known signal generation means for generating a predetermined known signal and transmitting it from the antenna in the distance measurement mode, and the communication device on the distance measuring side has the known signal in the distance measurement mode. A known signal processing means for receiving a known signal from the generating means and returning a signal based on the known signal from the antenna as a return signal; and the distance measuring side communication device further includes a distance between the two communication devices. The received power analysis means for analyzing the received power of the return signal from the distance-measured communication device, and the received power analyzed by the received power analysis means, between the two communication devices Distance Characterized in that it comprises a distance calculating means for calculating.

In one embodiment of the present invention, in the short-range wireless system, transmission of a known signal from the ranging-side communication device and return of a reply signal from the ranging-side communication device are performed by using the antenna. It is characterized by being directed in the direction of the communication device of the communication partner.

In one embodiment of the present invention, in the short-range wireless system, the reception-side communication device controls reception power control of a reception signal of a radio wave from the transmission-side communication device based on the calculated distance. And data demodulating means for demodulating a received signal, which is a radio wave adjusted with a control gain controlled by the received power control means, into data.

In one embodiment of the present invention, in the short-range wireless system, the two communication devices have a positioning mode for measuring an angle of a radio wave communication direction between the two communication devices, and the directivity is set in the positioning mode. A directivity control means for changing a directivity direction of the directional antenna a plurality of times, and a communication device on the positioning side of the two communication devices includes a radio wave received by the directional antenna and the directivity control in the positioning mode. An angle measuring means for calculating an angle of the direction of arrival of the received radio wave based on a directivity direction of the directional antenna changed by the means, and in the direction of arrival of the radio wave calculated by the angle measuring means, The directivity direction of the directional antenna is fixed.

One embodiment of the present invention is characterized in that, in the short-range wireless system, the directivity control means can arbitrarily change a three-dimensional spread of directivity of the directional antenna.

In one embodiment of the present invention, in the short-range wireless system, the directivity control means swings the directivity direction of the directional antenna in a plurality of directions during the positioning mode, and the angle measurement means includes the directional antenna. Power analysis means for analyzing the received power of the radio wave based on the radio wave received from the directional control information of the directional antenna by the directivity control means and outputting the received power analysis information; And an angle calculating means for calculating the angle of the direction of the received radio wave based on the received power analysis information of the power analyzing means.

In one embodiment of the present invention, in the short-range wireless system, the directivity control unit fixes a directivity direction of the directional antenna to an angle calculated by the angle calculation unit, and the power analysis unit It is characterized by reanalyzing the received power of the radio wave received from the directional antenna whose angle is fixed.

One embodiment of the present invention is based on gain control means for amplifying radio waves received by the directional antenna with a predetermined control gain in the short-range wireless system, and based on received power analysis information of the power analysis means. Gain calculating means for calculating a predetermined control gain of the gain control means and outputting it to the gain control means; and data demodulating means for demodulating radio wave data amplified by the predetermined control gain of the gain control means. It is characterized by that.

In one embodiment of the present invention, in the short-range wireless system, received power fluctuation detection for detecting that a fluctuation value of radio wave received power exceeds a predetermined threshold based on received power analysis information of the power analyzing means And a detection signal of the received power fluctuation detection means is notified to the directivity control means and the angle measurement means as a positioning start signal.

In one embodiment of the present invention, in the short-range wireless system, the communication device on the distance-measuring side detects an ambient temperature and transmits the detected temperature information to the communication device on the distance-measuring side. The arrival time calculation means provided in the communication device on the distance measuring side corrects the calculated arrival time based on the temperature information transmitted from the temperature detection means.

The short-range wireless communication device of the present invention is a short-range wireless communication device used in a short-range wireless system that performs transmission and reception of radio waves between two communication devices at a short distance, and the two communications based on the received radio waves. It is characterized by comprising distance calculation means for calculating the distance between devices, and transmission power control means for controlling the transmission power of radio waves to be transmitted based on the distance calculated by the distance calculation means.

The short-range wireless method of the present invention is a short-range wireless method for transmitting and receiving radio waves between two communication devices at a short distance, and calculates a distance between the two communication devices, and then, based on the calculated distance. The transmission power of the radio wave to be transmitted is controlled.

As described above, in the present invention, before data transmission / reception, the distance between two communication devices is estimated based on, for example, the arrival time of radio waves between the communication devices and the reception power of radio waves between the two communication devices communicating with each other. Since the transmission power of the radio wave is appropriately controlled based on the estimated distance, stable high speed communication with low power consumption can be realized.

In particular, in the present invention, in communication between two communication devices, the antenna is a directional antenna, and radio waves are transmitted toward the communication device of the communication partner, so that the distance between the two communication devices can be estimated accurately. Thus, the control of the transmission power of the radio wave becomes more appropriate, and the power consumption can be further reduced.

As described above, according to the present invention, in the short-range wireless system, before transmitting / receiving data, the distance between two communication devices that communicate with each other is estimated, and the transmission power of the radio wave is calculated based on the estimated distance. Proper control enables stable high-speed communication with low power consumption.

In particular, according to the present invention, since the communication between the two communication devices has a directivity in the direction of the communication device of the communication partner, the distance between the two communication devices can be estimated more accurately. The transmission power can be controlled more appropriately, and the power consumption can be further reduced.

FIG. 1 is a block diagram showing a short-range wireless system according to a first embodiment of the present invention. FIG. 2 is a flowchart showing the operation of the short-range wireless system. FIG. 3 is a flowchart showing the operation of the short-range wireless system according to the second embodiment of the present invention. FIG. 4 is a block diagram showing a short-range wireless system according to the third embodiment of the present invention. FIG. 5 is a flowchart showing the operation of the short-range wireless system. FIG. 6 is a block diagram showing a short-range wireless system according to the fourth embodiment of the present invention. FIG. 7 is a flowchart showing the operation of the short-range wireless system. FIG. 8 is a diagram showing an example of a millimeter length preamble length in the short-range wireless system according to the third embodiment of the present invention. FIG. 9 is a block diagram showing a short-range wireless system according to the fifth embodiment of the present invention. FIG. 10 is a flowchart showing the operation of the short-range wireless system. FIG. 11 is a block diagram showing a conventional short-range wireless system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows the configuration of a short-range wireless system according to a first embodiment of the present invention.

In the figure, 100 is four antennas, 101 is a known signal generation circuit, 102 is a data modulation circuit, 103 is a transmission power control circuit, 104 is a directivity control circuit, 105 is a known signal processing circuit, and 10 is a ranging circuit. , 11 is an angle measurement circuit, 106 is an arrival time calculation circuit, 107 is a distance calculation circuit, 108 is a power analysis circuit, 109 is an angle calculation circuit, 110 is a gain control circuit, and 111 is a data demodulation circuit. The configuration shown in FIG. 1 is adapted for beam forming with four antennas. Note that the number of antennas 100 may be two or more.

1 shows the configuration of one communication device. Of the two communication devices having this configuration, one communication device is the side that performs distance measurement in the positioning mode (hereinafter referred to as communication device 1), and the other communication device is the side that performs distance measurement in the positioning mode (hereinafter referred to as the communication device 1). This is a short-range wireless system in which the two communication devices perform wireless communication in the data communication mode.

Note that the communication device 1 and the communication device 2 may have the same configuration shown in FIG. 1 with respect to the short-range wireless system unit, and other components may be different components. For example, there are cases where a short-range wireless system unit is mounted on a BD recorder, DSC, DVC, Kiosk terminal, or the like.

The schematic configuration of each circuit will be described below. In FIG. 1, a known signal generation circuit 101 receives a positioning mode signal S 0, outputs a predetermined transmission signal (radio wave) S 1 in the positioning mode, and transmits it from the antenna 100. The data modulation circuit 102 receives the data communication mode signal S2, the transmission power value S4, and the gain control value S17, and modulates transmission data and outputs a transmission signal S3 in the data communication mode. Transmission power control circuit 103 receives data communication mode signal S2 and transmission signal S3 as inputs, and transmits transmission signal S5 after transmission power control from antenna 100 in the data communication mode.

The directivity control circuit 104 receives the positioning mode signal S0, the received power information S12, and the angle information S13, and outputs a directivity control signal S6 and directivity control information S7 for controlling the directivity of the antenna 100 in the positioning mode. Output. When controlling the directivity of the antenna 100, the directivity control circuit 104 can arbitrarily change the setting of the angle (three-dimensional spread of directivity) at which the antenna 100 is shaken each time. The known signal processing circuit 105 receives the positioning mode signal S0 and the reception signal S8 received from the antenna 100 as inputs, and transmits the predetermined reception signal from the antenna 100 after predetermined signal processing in the positioning mode.

The ranging circuit 10 receives the positioning mode signal S0, the received signal S8 received by the antenna 100, and the received power information S12, and calculates the distance between the two communication devices 1 and 2 in the positioning mode. Output as distance information S11. The angle measurement circuit 11 receives the positioning mode signal S0, the directivity control information S7, and the reception signal S8, and calculates the received power and the angle in the position direction of the communication devices 1 and 2 as communication partners in the positioning mode. The received power information S12 and the angle information S13 are output.

Further, the gain control circuit 110 receives the data communication mode signal S2, the reception signal S7, and the distance information S11, performs gain control in the data communication mode, and calculates from the reception signal S14 after gain control and the distance information S11. The gain control value S17 is output. The data demodulation circuit 111 receives the data communication mode signal S2 and the received signal S14 after gain control, demodulates the received signal S14 in the data communication mode, and receives the received data S15 and the transmission power value S16 of the communication device 1. The gain control value S18 of the communication device 1 is output.

The distance measuring circuit 10 includes an arrival time calculating circuit 106 and a distance calculating circuit 107. The arrival time calculation circuit 106 receives the positioning mode signal S0 and the reception signal S8 as inputs, and calculates the arrival time from the transmission of the transmission signal until the transmission signal is returned from the communication partner in the positioning mode, The arrival time information S10 is output. The distance calculation circuit 107 receives the positioning mode signal S0, the arrival time information S10, and the reception power information S12, and based on one or more pieces of information of the calculated arrival time and reception power, the two communication devices 1, The distance between the two is calculated and the distance information S11 is output.

Further, the angle measuring circuit 11 includes a power analysis circuit 108 and an angle calculation circuit 109. The power analysis circuit 108 receives the positioning mode signal S0, the directivity control information S7, and the received signal S8, and outputs the received power analysis information S11 and the received power S12 after the directionality is fixed in the positioning mode. To do. The angle calculation circuit 109 receives the positioning mode signal S0 and the received power analysis information S11, calculates the angle in the position direction to the communication devices 1 and 2 as communication partners in the positioning mode, and the angle information S13. Is output.

Next, the operation of each circuit of the short-range wireless system of FIG. 1 will be described in detail with reference to the flowchart shown in FIG.

In the communication device 1 (for example, a mobile phone), as described on the left side of FIG. 2, when the positioning mode signal S0 is valid, the antenna 100 is first made omnidirectional by the directivity control signal S6 output from the directivity control circuit 104. After that, a predetermined transmission signal S1 generated from the known signal generation circuit 101 is transmitted from the omnidirectional antenna 100 at an arbitrary interval. The predetermined transmission signal S1 may be a pulse signal or other signal.

In the communication device 2 (for example, a Blu-ray recording / reproducing apparatus), as described on the right side of FIG. 2, when the positioning mode signal S0 is valid, the antenna 100 is connected by the directivity control signal S6 output from the directivity control circuit 104. After setting to omnidirectional, a signal is received by the omnidirectional antenna 100, power analysis of the received signal is performed by the power analysis circuit 108, and received power information S12 as a result of the power analysis exceeds a certain threshold value. If it is determined that the transmission signal has been received from the communication device 1. When it is determined that a transmission signal has arrived, the antenna 100 is set to be directional by the directivity control signal S6 output from the directivity control circuit 104, and the directivity of the antenna 100 is swung in a plurality of directions. Then, the power analysis is performed by the power analysis circuit 108, and the reception power analysis information S11 in which the magnitude of the reception power and the directionality of the antenna 100 are associated is generated from the reception power and the directivity control information S7. The angle calculation circuit 109 calculates the angle of the position direction of the communication device 1 as the communication partner based on the generated received power analysis information S11, and estimates the arrival direction of the transmission signal. Furthermore, in the communication device 2, after completion of the estimation of the arrival direction, the directivity control signal S 6 output from the directivity control circuit 104 changes the directivity of the antenna 100 to the estimated direction in which the communication device 1 is located. To fix. Thereafter, the transmission signal S1 from the communication device 1 is received by the antenna 100 whose directivity is fixed in the direction of the communication device 1, and after the predetermined signal processing by the known signal processing circuit 105, the directivity is fixed as the transmission signal S9. Is returned from the antenna 100 to the communication device 1. The predetermined signal processing may be processing for detecting a waveform transmitted from the communication device 1 and shaping the waveform, or may be other processing.

Thereafter, in the communication device 1, the power analysis of the signal received by the antenna 100 set to its own omnidirectional is performed by the power analysis circuit 108, and when the received power of the analysis result exceeds a predetermined threshold, It is determined that the transmission signal S9 returned from the communication device 2 has been received. If it is determined that the transmission signal S9 is received from the communication device 2, the reception power of the reception signal and the transmission of the transmission signal S1 from the communication device 1 are transmitted based on the reception signal S9. The arrival time of the signal from the time until reception of the received signal S9 is calculated, and the distance between the two communication devices 1 and 2 is calculated and estimated based on at least one of the calculated reception power and arrival time. .

Hereinafter, calculation and estimation of the distance between the communication devices 1 and 2 will be described. In the communication device 1, after determining that the transmission signal S9 from the communication device 2 has been received, the antenna 100 is set to directivity by the directivity control signal S6 output from the directivity control circuit 104. A power analysis is performed on the transmission signal S9 from the communication device 2 by the power analysis circuit 108 of the angle measurement circuit 10 while oscillating the directivity in a plurality of directions. The received power of the analysis result and the directivity of the directivity control circuit 104 are analyzed. The received power analysis information S11 in which the magnitude of the received power of the transmission signal S9 from the communication device 2 is associated with the direction of directivity is created based on the sex control information S7. Thereafter, the angle calculation circuit 109 of the angle measurement circuit 10 calculates the angle of the position direction of the communication device 2 based on the received power analysis information S11, and estimates the arrival direction of the transmission signal S9. Further, in the communication device 1, after completion of the estimation of the arrival direction, the directivity of the antenna 100 is set in the direction in which the communication device 2 is estimated to be located by the directivity control signal S 6 output from the directivity control circuit 104. Fix the angle.

In parallel with the processing of the angle measurement circuit 11, the communication device 1 uses the arrival time calculation circuit 106 of the distance measurement circuit 10 to transmit the transmission signal S 1 from the communication device 1 through the communication device 2 through the communication device 2. The arrival time until it arrives at the communication device 1 as the transmission signal S9 is calculated based on the following equations 1 and 2.

Arrival time = transmission arrival time (communication device 1 → communication device 2)
+ Internal processing time (fixed delay of communication device 2)
+ Reception arrival time (communication device 2 → communication device 1) Equation 1
Arrival time of communication devices 1 and 2 = (arrival time−internal processing time) / 2 Formula 2

The arrival time calculation circuit 106 outputs the calculated arrival time of the transmission signal between the communication devices 1 and 2 as arrival time information S10. The distance calculation circuit 107 calculates the distance between the communication devices 1 and 2 from the calculated arrival time according to the following Equation 3.

Distance = Time × Speed of light (3 × 10 ⁸ m / s) Equation 3

The calculation of the distance is based on the above formulas 1, 2, and 3, but may be calculated based on other formulas.

In the expressions 1 and 2, the internal processing time included in these expressions is mainly the processing time of the known signal processing circuit 105. Various configurations can be assumed for the configuration of the known signal processing circuit 105, but an error component is included when a signal passes through a block composed of an analog circuit that is a component of the known signal processing circuit 105. Since it fluctuates according to the temperature fluctuation of the analog circuit, the influence of the temperature fluctuation on the distance information S11 becomes large. Therefore, in addition to estimating the distance between the communication devices 1 and 2 based on the arrival time, the distance is estimated based on the received power.

The distance is estimated based on the received power as follows. That is, when the communication device 2 returns the transmission signal S9 from the antenna 100 with fixed directivity to the communication device 1, the transmission power of the transmission signal S9 is set to a predetermined transmission power. Then, with the directivity of the antenna 100 of the communication devices 1 and 2 fixed at the angle of the direction of the communication partner, the received power of the transmission signal S9 is remeasured using the power analysis circuit 108 of the communication device 1. . Thereby, since the directivity is fixed, the received power that is not affected by the multipath can be measured. And the distance between the communication apparatuses 1 and 2 is estimated based on this received power. The distance is estimated and calculated by using the property that the propagation loss of received power is proportional to the square of the distance and inversely proportional to the square of the wavelength.

Thus, the ranging accuracy can be improved by performing ranging using one or more pieces of information of the calculated arrival time information S10 and re-measured received power information S12. The transmission power control circuit 103 controls the transmission power based on the calculated and estimated distance information S11. This transmission power control is possible by having a table in which the correspondence relationship between the distance and the transmission power value is stored in advance in the transmission power control circuit 103, and the characteristics of the transmission power control circuit 103 are taken into account by this table. Transmission power control can be performed. Other methods may also be used.

Further, the gain control circuit (reception power control means) 110 is preliminarily applied to the gain control circuit (reception power control means) 110 based on the distance information S11 measured using at least one of the arrival time information S10 and the remeasured reception power information S12. An appropriate gain control value S17 for the communication device 1 can be set. This is because the propagation loss of received power can be calculated from the distance as described above.

When the positioning mode ends and the mode shifts from the positioning mode to the data communication mode, the received data is demodulated as follows. That is, at the time of the first wireless communication from the communication device 1 to the communication device 2, an appropriate transmission power value S4 calculated by the transmission power control circuit 103 of the communication device 1 and an appropriate value set by the gain control circuit 110. The gain control value S17 is sent to the data modulation circuit 102, and the information S4 and S17 are modulated together with other data to form a transmission signal S3. The transmission power of the transmission signal S3 is controlled by the transmission power control circuit 103. The transmission power value is controlled and transmitted from the directional antenna 100 as a transmission signal S5. In the communication device 2, the transmission signal S5 from the communication device 1 received by the directional antenna 100 is controlled by the gain control circuit 110 with a predetermined gain value, and then the transmission power value in the communication device 1 in the data demodulation circuit 111. S16 and the gain control value S17 in the communication device 1 are demodulated, and the transmission power value S16 of the communication device 1 is transmitted to the transmission power control circuit 103 of the communication device 2 and the gain control value S17 of the communication device 1 is The gain control circuit 110 of the communication device 2 is reset. When transmitting and receiving data between the communication devices 1 and 2, appropriate transmission power control of transmission data is performed in the transmission power control circuit 103, and an appropriate gain control value S 17 in the gain control circuit 110 is used as a reference. After the received data gain control is performed, the data demodulation circuit 111 demodulates the received data after the gain control.

Therefore, before starting communication between two communication devices, positioning is performed by a simple positioning method, and transmission power and reception power are appropriately controlled according to the value, and directional antennas are controlled, thereby reducing power consumption. In addition, stable high-speed short-range wireless communication that is not affected by multipath can be realized.

(Embodiment 2)
Subsequently, the short-range wireless system according to the second embodiment of the present invention will be described.

FIG. 3 shows an operation flowchart of the short-range wireless system according to the second embodiment of the present invention. The present embodiment relates to directivity control of the directional antenna 100. Since the configuration of the short-range wireless system of this embodiment is the same as that shown in FIG. 1, a detailed description thereof will be omitted.

In FIG. 3, in the communication device 1, when the positioning mode signal S0 is valid, the antenna 100 is set to directivity by the directivity control signal S6 output from the directivity control circuit 104, and the directivity antenna 100 is set to a plurality of directivity antennas 100. The transmission signal S1 generated from the known signal generation circuit 101 is transmitted from the directional antenna 100 at an arbitrary time interval while swinging in the direction. The transmission signal S1 may be a pulse signal or other signals.

As a result, even in the positioning mode, the directivity gain can be obtained by making the directivity more than the setting for transmitting by the non-directional antenna 100 in the case of the first embodiment, and the transmission power corresponding to that can be obtained. It is possible to reduce the power consumption and to further reduce power consumption.

However, since the directivity of each antenna 100 is swung in a plurality of directions in both the communication devices 1 and 2, it may take time to find accurate received power because the directivity directions of each other do not match. In this case, if the received power cannot be detected after a predetermined time, which is the power analysis circuit 108 of the communication device 2, the detection of the received power is accelerated by widening the three-dimensional spread of directivity of the communication devices 1 and 2. May be. The subsequent operation flow of the second embodiment is the same as that of the first embodiment.

(Embodiment 3)
Next, a short-range wireless system according to the third embodiment of the present invention will be described.

FIG. 4 shows the configuration of the short-range wireless system according to the third embodiment of the present invention. In the figure, 100 is four antennas, 101 is a known signal generation circuit, 102 is a data modulation circuit, 103 is a transmission power control circuit, 104 is a directivity control circuit, 105 is a known signal processing circuit, and 10 is a ranging circuit. , 11 is an angle measurement circuit, 106 is an arrival time calculation circuit, 107 is a distance calculation circuit, 108 is a power analysis circuit, 109 is an angle calculation circuit, 110 is a gain control circuit, and 111 is a data demodulation circuit. The above configuration is the same as in FIG.

In the present embodiment, a gain calculation circuit 112 is further added. The gain calculation circuit 112 receives the re-measured received power information S12 after the directivity of the antennas 100 of the communication devices 1 and 2 is fixed, and calculates the gain control value S17 of the gain control circuit 110. Output.

Next, the operation of each part will be described in more detail with reference to the flowchart of FIG. 3 is different from the flowchart of FIG. 3 in that the communication device 1 has its own received power information after the re-measurement by the gain calculation circuit 112 based on the received power information S12 after the re-measurement by the power analysis circuit 108 in the positioning mode. An appropriate gain control value S17 corresponding to S12 is calculated, and the calculated gain control value S17 is set as an initial value of the gain control circuit 110. As a result, as shown in FIG. 8, even when the preamble defined by the millimeter wave standards (IEEE802.15.3c, ECMA, NGmS, etc.) is short (about 2 μ to 3 μ), it can be received at high speed. Signal gain control can be performed, and stable high-speed communication can be performed. In the communication device 2 as well, the gain calculation circuit 112 responds to the received power information S12 after remeasurement based on the received power information S12 after remeasurement by the own power analysis circuit 108, as described above. An appropriate gain control value S17 is calculated, and this gain control value S17 is set as an initial value of its own gain control circuit 110. Thereby, more stable high-speed communication can be performed.

(Embodiment 4)
FIG. 6 shows a configuration of a short-range wireless system according to the fourth embodiment of the present invention.

In the figure, 100 is four antennas, 101 is a known signal generation circuit, 102 is a data modulation circuit, 103 is a transmission power control circuit, 104 is a directivity control circuit, 105 is a known signal processing circuit, and 10 is a ranging circuit. , 11 is an angle measurement circuit, 106 is an arrival time calculation circuit, 107 is a distance calculation circuit, 108 is a power analysis circuit, 109 is an angle calculation circuit, 110 is a gain control circuit, and 111 is a data demodulation circuit. The above configuration is the same as in FIG.

In this embodiment, a reception power fluctuation detection circuit 113 is further added. The received power fluctuation detection circuit 113 receives, as input, received power information S12 obtained by measuring the received power continuously after re-measurement of the received power after the directivity of the antenna 100 of each of the communication devices 1 and 2 is fixed. The received power fluctuation information S20 is output to the directivity control circuit 104.

Next, the operation of the short-range wireless system of this embodiment will be described based on the flowchart of FIG.

As in the first or second embodiment, in the data communication mode, the communication devices 1 and 2 are modulated by the data modulation circuit 102 with the antenna 100 directed at the angle of the position of the other party. Data is transmitted at a transmission power value corresponding to the distance between the two communication devices, and the received data is demodulated by the data demodulation circuit 111 after gain control is performed based on an appropriate control gain value corresponding to the reception power. The

Here, the reception power fluctuation detection circuit 113 always receives the reception power information S12 obtained by continuously measuring the reception power by the power analysis circuit 108, and when the reception power information S12 exceeds a predetermined threshold, the communication is performed. It is determined that position movement of the devices 1 and 2 has occurred, and the reception power fluctuation information S20 is output as a positioning start signal to the directivity control circuit 104 and the angle measurement circuit 11, and the process returns to the positioning mode and thereafter. Again, calibrate with the positioning sequence.

Therefore, by monitoring the change in the received power, it is possible to follow a change in the situation such as the relative position movement of the communication devices 1 and 2 and perform stable high-speed communication.

(Embodiment 5)
FIG. 9 shows the configuration of a short-range wireless system according to the fifth embodiment of the present invention.

In this embodiment, a temperature detection circuit 1050 is further disposed inside the known signal processing circuit 105. The function and operation of this temperature detection circuit 1050 will be described below.

As described above in Equations 1 and 2, the arrival time of the signal between the communication devices 1 and 2 also depends on the processing time of the known signal processing circuit 105, and this processing time is a temperature fluctuation of the known signal processing circuit 105. In the present embodiment, the temperature of the known signal processing circuit 105 is detected by the temperature detection circuit 1050 built in the known signal processing circuit 105, and the communication device 1 according to the equations 1 and 2 is based on this temperature information. The arrival time of the signal between the two is corrected.

Specifically, as shown in the flowchart of FIG. 10, the temperature information S21 detected by the temperature detection circuit 1050 is multiplexed with the transmission signal S9, and the communication device 2 transmits the communication device 2 from the antenna 100 with the fixed directivity. 1 is transmitted. In the communication device 1, the arrival time calculation circuit 106 corrects the arrival time based on the temperature information S21. In this correction, for example, a time that affects the internal processing time corresponding to the temperature of the known signal processing circuit 105 is stored in a table, and the arrival time calculated by the arrival time calculation circuit 106 is corrected according to this table.

Therefore, in this embodiment, the distance calculation accuracy between the communication devices 1 and 2 can be improved and the transmission power of the transmission signal can be more appropriately controlled without being affected by the temperature fluctuation of the known signal processing circuit 105.

The temperature information S21 may be notified from the communication device 2 to the communication device 1 when the data communication mode signal S2 is valid. In that case, the power control value is reset again.

As described above, the present invention estimates the distance between two communication devices that communicate with each other before transmitting and receiving data, and appropriately controls the transmission power of radio waves based on the estimated distance, thereby reducing power consumption. Therefore, it is useful when applied to a high-speed short-range wireless system of several hundred Mbps to several Gbps using millimeter waves indoors.

100, 200 Antenna 101 Known signal generation circuit (known signal generation means)
102, 201 Data modulation circuit (data modulation means)
103 Transmission power control circuit (transmission power control means)
104, 202 Directivity control circuit (directivity control means)
105 Known signal processing circuit (known signal processing means)
10. Ranging circuit 106 Arrival time calculation circuit (arrival time calculation means)
107 Distance calculation circuit (distance calculation means)
11 Angle measurement circuit (angle measurement means)
108 Power analysis circuit (power analysis means, received power analysis means)
109 Angle calculation circuit (angle calculation means)
110 Gain control circuit (gain control means, received power control means)
111, 206 Data demodulation circuit (data demodulation means)
112 Gain calculation circuit (gain calculation means)
113 Received power fluctuation detecting circuit (Received power fluctuation detecting means)
203 Delay time measuring circuit (delay time measuring means)
204 Arrival direction measuring circuit (arrival direction measuring means)
205 Position calculation circuit (position calculation means)
1050 Temperature detection circuit (temperature detection means)

Claims

A short-range wireless system that transmits and receives radio waves between two communication devices at a short distance,
Estimating the distance between the two communication devices;
Based on the estimated distance, a transmission power of the radio wave is controlled in a transmission-side communication device that transmits the radio wave.
The short-range wireless system according to claim 1,
The two communication devices have a data communication mode for wirelessly communicating data between the two communication devices,
The communication device on the transmission side that transmits the data is:
An antenna for data transmission;
Data modulating means for modulating data to be transmitted in the data communication mode;
Transmission power control means for controlling the transmission power of the data modulated by the data modulation means based on the estimated distance between the two communication devices and transmitting the data after the power control from the antenna. A short-range wireless system characterized by this.
The short-range wireless system according to claim 1,
The short-range wireless system, wherein the distance is estimated based on at least one of the arrival time and the reception power of the radio wave.
The short-range wireless system according to claim 1,
The receiving side communication device that receives the radio wave is:
A short-range wireless system, wherein reception power control is performed to control a control gain of a reception signal that receives a radio wave from the transmission-side communication device.
The short-range wireless system according to claim 1,
The two communication devices are:
With a directional antenna,
Estimate the angle at which the communication device on the communication partner side is located relative to your communication device,
The near field wireless system characterized by controlling the directional antenna in the direction of the estimated angle.
The short-range wireless system according to claim 3,
The two communication devices have a distance measuring mode for measuring a distance between the two communication devices,
Of the two communication devices, the communication device on the distance measuring side has a known signal generating means for generating a predetermined known signal and transmitting it from the antenna in the distance measuring mode,
The distance-measurement-side communication device includes a known signal processing unit that receives a known signal from the known signal generation unit and returns a signal based on the known signal from the antenna as a return signal in the ranging mode.
The distance-measuring communication device further calculates an arrival time from the transmission of the known signal to the arrival of a return signal from the distance-measuring-side communication device with respect to the estimation of the distance between the two communication devices. A short-range wireless system comprising: arrival time calculation means; and distance calculation means for calculating a distance between the two communication devices based on the arrival time calculated by the arrival time calculation means.
The short-range wireless system according to claim 3,
The two communication devices have a distance measuring mode for measuring a distance between the two communication devices,
Of the two communication devices, the communication device on the distance measuring side has a known signal generating means for generating a predetermined known signal and transmitting it from the antenna in the distance measuring mode,
The distance-measurement-side communication device includes a known signal processing unit that receives a known signal from the known signal generation unit and returns a signal based on the known signal from the antenna as a return signal in the ranging mode.
The distance measurement side communication device further includes a received power analysis means for analyzing a received power of a return signal from the distance measurement side communication device for estimating a distance between the two communication devices, and the received power. A short-range wireless system, comprising: distance calculation means for calculating a distance between the two communication devices based on the received power analyzed by the analysis means.
The short-range wireless system according to claim 7, wherein
Transmission of the known signal from the communication device on the distance measuring side and return of the reply signal from the communication device on the distance measuring side are performed with the antenna directed toward the communication device of the communication partner. A short-range wireless system that is characterized.
The short-range wireless system according to claim 4,
The receiving side communication device is:
A reception power control means for controlling a control gain of a reception signal of a radio wave from the transmission-side communication device based on the calculated distance;
A short-range wireless system comprising: a data demodulating unit that demodulates a received signal, which is a radio wave adjusted with a control gain controlled by the received power control unit, into data.
The short-range wireless system according to claim 5,
The two communication devices have a positioning mode for measuring the angle of the radio wave communication direction between the two communication devices,
Directivity control means for changing the directivity direction of the directional antenna a plurality of times during the positioning mode;
Of the two communication devices, the communication device on the positioning side is based on the radio wave received by the directional antenna and the directional direction of the directional antenna changed by the directional control means in the positioning mode. And angle measuring means for calculating an angle of arrival direction of the received radio wave,
The short-range wireless system, wherein the directivity direction of the directional antenna is fixed to the arrival direction of the radio wave calculated by the angle measuring means.
The short-range wireless system according to claim 10,
The directivity control means includes
A short-distance radio system, wherein the three-dimensional spread of directivity of the directional antenna can be arbitrarily changed.
The short-range wireless system according to claim 10,
The directivity control means swings the directivity direction of the directional antenna in a plurality of directions during the positioning mode,
The angle measuring means includes
Power analysis that analyzes the received power of the radio wave based on the radio wave received from the directional antenna and the directivity control information of the directional antenna by the directivity control means and outputs the received power analysis information Means,
A short-range wireless system, comprising: an angle calculation unit that calculates an angle of a direction of a received radio wave based on the received power analysis information of the power analysis unit.
The short-range wireless system according to claim 10,
The directivity control means fixes the directivity direction of the directional antenna to the angle calculated by the angle calculation means,
The near field wireless system characterized in that the power analysis means reanalyzes the received power of the radio wave received from the directional antenna whose angle is fixed.
The short-range wireless system according to claim 12 or 13,
Gain control means for amplifying radio waves received by the directional antenna with a predetermined control gain;
Gain calculation means for calculating a predetermined control gain of the gain control means based on the received power analysis information of the power analysis means and outputting the gain to the gain control means;
A short-range wireless system comprising: a data demodulating unit that demodulates radio wave data amplified by the predetermined control gain of the gain control unit.
The short-range wireless system according to claim 12 or 13,
Based on the received power analysis information of the power analysis means, comprising a received power fluctuation detection means for detecting that the fluctuation value of the received power of the radio wave exceeds a predetermined threshold,
The near field wireless system characterized in that the detection signal of the received power fluctuation detecting means is notified to the directivity control means and the angle measuring means as a positioning start signal.
The short-range wireless system according to claim 6, wherein
The distance measuring side communication device is provided with temperature detecting means for detecting an ambient temperature and transmitting the detected temperature information to the distance measuring side communication device,
The short-range wireless system, wherein the arrival time calculation means provided in the communication device on the distance measuring side corrects the calculated arrival time based on temperature information transmitted from the temperature detection means.
A short-range wireless communication device used in a short-range wireless system that transmits and receives radio waves between two communication devices at a short distance,
Distance calculating means for calculating a distance between the two communication devices based on received radio waves;
A short-range wireless communication device, comprising: a transmission power control unit that controls transmission power of a radio wave to be transmitted based on the distance calculated by the distance calculation unit.
In a short-range wireless method for transmitting and receiving radio waves between two communication devices at a short distance,
Calculating the distance between the two communication devices;
Then, based on the calculated distance, the transmission power of the radio wave to be transmitted is controlled.