WO2014181446A1

WO2014181446A1 - Communications system, control device, and control method

Info

Publication number: WO2014181446A1
Application number: PCT/JP2013/063091
Authority: WO
Inventors: 義博河▲崎▼
Original assignee: 富士通株式会社
Priority date: 2013-05-09
Filing date: 2013-05-09
Publication date: 2014-11-13

Abstract

A first communications device (110) wirelessly sends synchronous signals. A second communications device (120) and a third communications device (130) can directly communicate with each other and at least one is wirelessly connected to the first communications device (110). A control device (140): wirelessly sends, from the second communications device (120) and at the same timing as the transmission of the synchronous signals, a measurement signal having a waveform pattern orthogonal to the synchronous signals and having the same frequency band; and receives from the third communications device (130) the reception results for the measurement signal in the third communications device (130).

Description

COMMUNICATION SYSTEM, CONTROL DEVICE, AND CONTROL METHOD

The present invention relates to a communication system, a control device, and a control method.

In order to further increase the speed and capacity of commercial wireless communication systems such as mobile phones and wireless LANs, various groups are discussing next-generation wireless communication technologies. For example, in 3GPP (3rd Generation Partnership Project), which is a standardization organization, a communication standard called LTE (Long Term Evolution) has already been formulated, and communication called LTE-A (LTE-Advanced) based on LTE wireless communication technology Examination and specification development work is being carried out to expand the functionality of the standard.

In 3GPP, D2D (Device to Device) communication in which mobile phones directly communicate with each other without using a base station has been studied from the viewpoint of service (for example, see Non-Patent Document 1 below). Feasibility, technology necessary for realization, expected characteristics, and the like have been studied (for example, see Non-Patent Document 2 below).

In the above-described prior art, for example, in order to determine whether direct communication between terminals is possible in a base station, it is conceivable to measure communication quality between terminals by transmitting a measurement signal between terminals. However, when a measurement signal is transmitted between terminals, there is a problem that the measurement signal interferes with communication performed between the base station and another terminal.

In one aspect, an object of the present invention is to provide a communication system, a control device, and a control method capable of measuring communication quality while suppressing interference.

In order to solve the above-described problems and achieve the object, according to one aspect of the present invention, at least one of the first communication devices that wirelessly transmits a synchronization signal is wirelessly connected and can communicate directly with each other. When controlling the communication device and the third communication device, the measurement signal having the same frequency band and the waveform pattern orthogonal to the synchronization signal is wirelessly transmitted from the second communication device in accordance with the transmission timing of the synchronization signal, A communication system, a control device, and a control method for receiving a reception result of the measurement signal in the third communication device from the third communication device are proposed.

According to one aspect of the present invention, it is possible to measure communication quality while suppressing interference.

FIG. 1A is a diagram of an example of a communication system according to the first embodiment. 1B is a diagram illustrating an example of a signal flow in the communication system illustrated in FIG. 1A. FIG. 2A is a diagram (part 1) illustrating an example of a communication system according to a second embodiment. FIG. 2B is a diagram (part 2) illustrating an example of a communication system according to the second embodiment. FIG. 2C is a diagram (part 3) illustrating an example of a communication system according to the second embodiment. FIG. 2D is a diagram (part 4) illustrating an example of a communication system according to the second embodiment. FIG. 3 is a diagram illustrating an example of correspondence information between the waveform pattern parameter and the transmission power of the measurement signal. FIG. 4A is a diagram illustrating an example of a configuration of a base station. 4B is a diagram illustrating an example of a signal flow in the configuration of the base station illustrated in FIG. 4A. FIG. 5A is a diagram illustrating an exemplary configuration of a terminal. FIG. 5B is a diagram illustrating an example of a signal flow in the configuration of the terminal illustrated in FIG. 5A. FIG. 6 is a flowchart illustrating an example of processing by the base station. FIG. 7 is a flowchart illustrating an example of processing by the terminal. FIG. 8 is a sequence diagram illustrating an example of a measurement operation in the communication system. FIG. 9 is a diagram illustrating an example of PSS transmission timing. FIG. 10 is a diagram illustrating an example of grouping of transmission powers of measurement signals. FIG. 11 is a flowchart illustrating an example of processing for determining the transmission power of a measurement signal.

Hereinafter, embodiments of a communication system, a control device, and a control method according to the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1A is a diagram of an example of a communication system according to the first embodiment. 1B is a diagram illustrating an example of a signal flow in the communication system illustrated in FIG. 1A. As illustrated in FIGS. 1A and 1B, the communication system 100 according to the first embodiment includes a first communication device 110, a second communication device 120, a third communication device 130, and a control device 140. The first communication device 110, the second communication device 120, and the third communication device 130 are devices capable of wireless communication.

The control device 140 can communicate with the second communication device 120 and the third communication device 130 via wireless communication by the first communication device 110. In the example illustrated in FIGS. 1A and 1B, the case where the control device 140 is provided in the first communication device 110 will be described. However, the control device 140 can communicate with the first communication device 110 outside the first communication device 110. It may be a device.

The first communication device 110 includes a transmission unit 111 and a control device 140. The transmission unit 111 wirelessly transmits a synchronization signal. The synchronization signal is a periodic signal having a predetermined waveform pattern for another communication device to synchronize wireless communication with the first communication device 110.

At least one of the second communication device 120 and the third communication device 130 is a communication device that is wirelessly connected to the first communication device 110. In the example shown in FIGS. 1A and 1B, both the second communication device 120 and the third communication device 130 are wirelessly connected to the first communication device 110, but one of the second communication device 120 and the third communication device 130 is The wireless communication device may be wirelessly connected to another communication device that can communicate with the first communication device 110. The second communication device 120 and the third communication device 130 can directly communicate with each other wirelessly.

The control device 140 includes a control unit 141 and a reception unit 142. The control unit 141 has a waveform pattern orthogonal to the synchronization signal transmitted by the transmission unit 111 and the measurement signal having the same frequency band as the synchronization signal transmitted by the transmission unit 111 in accordance with the transmission timing of the synchronization signal by the transmission unit 111. Control to wirelessly transmit from the second communication device 120 is performed.

For example, the control unit 141 transmits a measurement signal from the second communication device 120 by transmitting a control signal including a parameter capable of deriving a waveform pattern orthogonal to the synchronization signal transmitted by the transmission unit 111 to the second communication device 120. Let it transmit wirelessly. Further, the control unit 141 may further notify the second communication device 120 of the frequency of the measurement signal. The control unit 141 may also transmit a control signal including a parameter that can derive a waveform pattern orthogonal to the synchronization signal transmitted by the transmission unit 111 to the third communication device 130.

The receiving unit 142 receives from the third communication device 130 the reception result of the measurement signal wirelessly transmitted from the second communication device 120 by the third communication device 130 under the control of the control unit 141.

The second communication device 120 includes a reception unit 121 and a transmission unit 122. The receiving unit 121 receives a control signal transmitted from the control device 140. Then, the reception unit 121 outputs the parameters included in the received control signal to the transmission unit 122.

The transmission unit 122 generates a measurement signal whose waveform pattern is orthogonal to the synchronization signal wirelessly transmitted by the first communication device 110 based on the parameter output from the reception unit 121. Then, the transmission unit 122 wirelessly transmits the generated measurement signal in accordance with the transmission timing of the synchronization signal by the first communication device 110.

For example, the second communication device 120 detects the synchronization signal of the first communication device 110. And the transmission part 122 transmits a measurement signal according to the transmission timing of the synchronizing signal by the 1st communication apparatus 110 based on the detected timing. The transmission power (transmission power) of the measurement signal can be set to a preset transmission power, for example.

The third communication device 130 includes a reception unit 131 and a transmission unit 132. The receiving unit 131 receives a measurement signal wirelessly transmitted from the second communication device 120. For example, the receiving unit 131 receives the control signal transmitted from the control device 140, derives a waveform pattern of the measurement signal based on parameters included in the received control signal, and performs the second communication based on the derived waveform pattern. A measurement signal from device 120 is received.

Then, the reception unit 131 outputs the reception result of the measurement signal to the transmission unit 132. The reception result of the measurement signal can be, for example, the reception power (reception power) of the measurement signal in the third communication device 130. Alternatively, the reception result of the measurement signal may be a propagation loss (path loss) based on a comparison between the transmission power of the measurement signal in the second communication device 120 and the reception power of the measurement signal in the third communication device 130.

The transmission unit 132 transmits the reception result output from the reception unit 131 to the control device 140. Accordingly, the control device 140 can obtain a reception result of the measurement signal wirelessly transmitted from the second communication device 120 in the third communication device 130. For this reason, the communication quality between the 2nd communication apparatus 120 and the 3rd communication apparatus 130 can be measured.

As described above, according to the communication system 100 according to the first embodiment, the second communication device 120 and the second communication device 120 are connected to the second communication device 120 using the measurement signal of the same radio resource (time and frequency) as the synchronization signal wirelessly transmitted by the first communication device 110. The communication quality with the three communication devices 130 can be measured. Thereby, it is possible to measure the communication quality between the second communication device 120 and the third communication device 130 without vacating radio resources for the measurement signal. For this reason, the compression of the radio | wireless resource by a measurement signal can be suppressed.

Further, even if the measurement signal has the same radio resource as the synchronization signal of the first communication device 110, the cross-correlation value between the synchronization signal and the measurement signal can be obtained by using the measurement signal whose waveform pattern is orthogonal to the synchronization signal. Can be lowered. For this reason, the interference by the measurement signal with respect to the synchronous signal which the 1st communication apparatus 110 transmits can be suppressed.

Therefore, the communication quality between the second communication device 120 and the third communication device 130 can be measured while suppressing interference with the communication of the first communication device 110.

<Transmission power control>
The transmission power of the measurement signal from the second communication device 120 may be determined by the control device 140. In this case, for example, the second communication device 120, the third communication device 130, and the control device 140 share correspondence information that associates the waveform pattern parameter notified by the control device 140 with the transmission power of the measurement signal.

The control device 140 selects a parameter corresponding to the determined transmission power among the parameters capable of deriving a waveform pattern orthogonal to the synchronization signal transmitted by the transmission unit 111 based on the correspondence information. Then, control device 140 transmits a control signal including the selected parameter to second communication device 120 and third communication device 130.

The transmission unit 122 of the second communication device 120 wirelessly transmits the measurement signal with the transmission power corresponding to the parameter included in the control signal received by the reception unit 121 based on the correspondence information. The receiving unit 131 of the third communication device 130 specifies the transmission power corresponding to the parameter included in the control signal transmitted from the control device 140 based on the correspondence information. Then, the reception unit 131 calculates the propagation loss of the measurement signal based on the comparison between the specified transmission power and the reception power of the received measurement signal.

Thereby, the transmission power of the measurement signal can be notified to the second communication device 120 and the third communication device 130 using the parameter for notifying the waveform pattern of the measurement signal. Thereby, the information amount of a control signal can be reduced.

For example, when the third communication device 130 transmits reception power to the control device 140 as a reception result, the transmission power of the measurement signal may be unknown in the third communication device 130, so the third communication device 130 The correspondence information need not be shared. In this case, the control device 140 may calculate the propagation loss of the measurement signal based on a comparison between the determined transmission power of the measurement signal and the reception power transmitted as the reception result from the third communication device 130. .

(Embodiment 2)
(Communication system according to Embodiment 2)
2A to 2D are diagrams illustrating an example of a communication system according to the second embodiment. As illustrated in FIG. 2A, the communication system 200 according to the second embodiment includes a base station 210, a first terminal 221, a second terminal 222, and a third terminal 223. The base station is also called NodeB, eNodeB, and Basestation.

The base station 210 transmits PSS (Primary Synchronization Signal) periodically (every 5 ms in the latest 3GPP LTE specifications). The waveform pattern of the PSS transmitted by the base station 210 is associated with the cell ID of the base station 210, for example. In the LTE specification, in addition to PSS, a synchronization signal called SSS (Secondary Synchronization Signal) is defined, and both PSS and SSS are transmitted on the radio downlink. The physical layer ID (PCI: Physical Cell ID) of each radio cell (Cell) of the base station is associated with both PSS and SSS, and the terminal receives both PSS and SSS so that they are transmitted. It becomes possible to know the PCI of the wireless cell. Usually, one base station forms a plurality of radio cells, and one radio cell is composed of only Pcell (Primary Cell), or further composed of Pcell and one or more Scell (Secondary Cell). The

The first terminal 221, the second terminal 222, and the third terminal 223 are wireless communication terminals capable of wireless communication with the base station 210. The wireless communication terminal is also called UE (User Equipment) or MS (Mobile Station). The first terminal 221, the second terminal 222, and the third terminal 223 can synchronize wireless communication with the base station 210 by detecting the PSS transmitted from the base station 210. Normally, a PSS is transmitted for each radio cell of a base station, and the parameter values for determining the PSS signal waveform are set to be different between PSSs transmitted between the radio cells. The same value may be used between different wireless cells.

In the communication system 200, for example, it is assumed that the first terminal 221 and the second terminal 222 can directly communicate with each other wirelessly under moderate control by the base station 210. The first communication device 110 and the control device 140 illustrated in FIGS. 1A and 1B can be realized by the base station 210, for example. The second communication device 120 illustrated in FIGS. 1A and 1B can be realized by the first terminal 221, for example. The third communication device 130 illustrated in FIGS. 1A and 1B can be realized by the second terminal 222, for example.

First, as shown in FIG. 2A, it is assumed that the first terminal 221 and the second terminal 222 are communicating with each other via the base station 210. Since the first terminal 221 and the second terminal 222 located in the same cell are communicating with each other, the base station 210 determines whether direct communication between the first terminal 221 and the second terminal 222 is possible. For this purpose, the base station 210 performs control to cause the measurement signal from the first terminal 221 to be wirelessly transmitted and the measurement signal from the first terminal 221 to be received by the second terminal 222 as illustrated in FIG. 2B.

As shown in FIG. 2C, the second terminal 222 wirelessly transmits to the base station 210 report information indicating a reception result at the second terminal 222 of the measurement signal wirelessly transmitted from the first terminal 221. Base station 210 determines whether direct communication between first terminal 221 and second terminal 222 is possible based on the report information received from second terminal 222.

If the base station 210 determines that direct communication is possible, the base station 210 transmits a control signal to the first terminal 221 and the second terminal 222, as shown in FIG. 2 Direct communication with the terminal 222 is started. At this time, the band in the direct communication between the first terminal 221 and the second terminal 222 may be a band used by the base station 210 with the terminal, for example.

In FIG. 2B, the base station 210 causes the first terminal 221 to transmit a measurement signal whose waveform pattern is orthogonal to the PSS transmitted by the base station 210 at the same time and frequency as the PSS transmitted by the base station 210. As a result, the communication quality between the first terminal 221 and the second terminal 222 can be measured without vacating radio resources for the measurement signal. For this reason, it is possible to suppress the compression of radio resources due to the measurement signal.

Also, by using a measurement signal whose waveform pattern is orthogonal to the PSS of the base station 210, the cross-correlation value between the PSS of the base station 210 and the measurement signal can be lowered. For this reason, the interference by the measurement signal with respect to the PSS transmitted from the base station 210 can be suppressed. For example, interference by the measurement signal from the first terminal 221 when the third terminal 223 detects and synchronizes the PSS transmitted by the base station 210 can be suppressed.

(PSS waveform pattern)
Here, the waveform pattern of the PSS transmitted from the base station 210 will be described. For example, the base station 210 periodically transmits a PSS having a waveform pattern derived by the following equation (1). In the following formula (1), n indicates a bit position. u is a parameter for determining the waveform pattern, and is associated with the cell ID of the base station 210, for example.

(Correspondence information between waveform pattern parameters and measurement signal transmission power)
FIG. 3 is a diagram illustrating an example of correspondence information between the waveform pattern parameter and the transmission power of the measurement signal. The base station 210, the first terminal 221 and the second terminal 222 store, for example, correspondence information 300 shown in FIG. 3 in respective memories. The parameter u of the correspondence information 300 is a parameter that can derive a waveform pattern in which the waveform pattern is orthogonal to the PSS transmitted by the base station 210. The transmission power (P1, P2,...) Of the correspondence information 300 is the transmission power of the measurement signal (for example, the absolute value of the transmission power).

When the base station 210 determines the transmission power of the measurement signal, the base station 210 selects the parameter u corresponding to the determined power from the parameters u of the correspondence information 300. Then, the base station 210 transmits a control signal including the selected parameter u to the first terminal 221 and the second terminal 222. As the control signal, for example, PDCCH (Physical Downlink Control Channel: physical downlink control channel) or E-PDCCH (Enhanced-Physical Downlink Control Channel: extended physical downlink control channel) can be used. Or you may use PDSCH (Physical Downlink Shared Channel) used for transmission of a control signal of a higher layer more than a data signal and Layer2 (Mac Layer).

The first terminal 221 generates and transmits a parameter pattern PSS based on the parameter u included in the control signal received from the base station 210 and the above equation (1) as a measurement signal. In addition, the first terminal 221 sets the transmission power of the measurement signal as the transmission power corresponding to the parameter u in the correspondence information 300.

The second terminal 222 generates a replica signal having a waveform pattern based on the parameter u included in the control signal received from the base station 210 and the above equation (1). Then, the second terminal 222 detects the measurement signal transmitted from the first terminal 221 by comparing the received signal with the replica signal. Further, the second terminal 222 acquires the transmission power corresponding to the parameter u in the correspondence information 300, and compares it with the received power of the detected measurement signal, thereby causing a path loss between the first terminal 221 and the second terminal 222. Is calculated. Then, the second terminal 222 transmits report information including the calculated path loss to the base station 210. This report information may include other radio measurement results.

As a result of such wireless measurement, for example, a path loss between the second terminal 222 and the base station 210, a reception timing difference between the PSS transmitted from the base station 210 and the PSS transmitted from the first terminal 221. , Required signal power to noise interference power ratio (SIR: Signal-to-Interferencepower) (SIR: Cell-specific Reference Signal, CSI RS: Channel State Information Reference Signal, etc.) transmitted from the base station 210 There are radio characteristics of each division unit (subband) when the wireless transmission band (system bandwidth) is divided into a plurality of divisions.

These pieces of information are obtained when the base station 210 determines whether the D2D communication between the first terminal 221 and the second terminal 222 is possible or appropriate, and when the base station 210 performs the D2D communication, This is useful when determining values of wireless parameters used by the two terminals 222. The report information is transmitted to the base station 210 using PUSCH (Physical Uplink Shared Channel) used in the radio uplink.

For example, when the information to be reported is one type and the information size is small, PUCCH (Physical Uplink Control Channel) may be used. Various radio parameters of PUSCH or PUCCH to be used and resource information of PUSCH or PUCCH used by the terminal (information indicating the frequency position of PRB: Physical Resource Block directly or indirectly) is previously determined using the PDSCH. Or notified to the terminal using PDCCH or E-PDCCH. When notified using the PDCCH or E-PDCCH, include PUSCH or PUCCH resource information (PRB: information indicating the frequency location of the Physical Resource Block directly or indirectly) used in the terminal. Furthermore, information indicating directly or indirectly that the PUSCH or PUCCH is used for the purpose of transmitting report information may be included.

Thus, the transmission power of the measurement signal can be notified to the first terminal 221 and the second terminal 222 using the parameter u for notifying the waveform pattern of the measurement signal. Thereby, the information amount of a control signal can be reduced.

Also, in the correspondence information 300, the parameter u may not be directly associated with the transmission power, but may be information that associates the parameter u with the difference between the transmission power of the reference signal from the base station 210. The reference signal is a reference signal transmitted by the base station 210, and is, for example, CRS (cell specific reference signal) or CSI RS.

(Base station configuration)
FIG. 4A is a diagram illustrating an example of a configuration of a base station. 4B is a diagram illustrating an example of a signal flow in the configuration of the base station illustrated in FIG. 4A. The base station 210 shown in FIGS. 2A to 2D can be realized by the base station 400 shown in FIGS. 4A and 4B, for example.

The base station 400 includes a control signal generation unit 411, a data signal generation unit 412, multiplexing

units

413 and 414, an encoding / modulation unit 415, an RF transmission circuit 416, and a transmission antenna 417. In addition, the base station 400 includes a reception antenna 421, an RF reception circuit 422, a demodulation / decoding unit 423, and a demultiplexing unit 424.

The control signal generation unit 411, the data signal generation unit 412, the multiplexing

units

413 and 414, the encoding / modulation unit 415, the demodulation / decoding unit 423, and the demultiplexing unit 424 are, for example, LSI 401 (Large Scale Integration: large scale integrated circuit). Can be realized.

The control signal generation unit 411 generates a control signal for the base station 400 to wirelessly transmit. The control signal generated by the control signal generation unit 411 includes, for example, PSS transmission instruction information, PSS transmission stop instruction information, PSS detection instruction information, and other control information. The control signal generation unit 411 outputs the generated control signal to the multiplexing unit 413.

The data signal generator 412 generates a data signal for the base station 400 to wirelessly transmit based on the input user data. Then, the data signal generation unit 412 outputs the generated data signal to the multiplexing unit 413.

The multiplexing unit 413 multiplexes the control signal output from the control signal generation unit 411 and the data signal output from the data signal generation unit 412. Then, multiplexing section 413 outputs the signal obtained by multiplexing to multiplexing section 414. The multiplexing unit 414 multiplexes the signal output from the multiplexing unit 413 and the input pilot signal (or reference signal). Then, multiplexing section 414 outputs the signal obtained by multiplexing to encoding / modulating section 415.

The encoding / modulation unit 415 encodes and modulates the signal output from the multiplexing unit 414. The encoding by the encoding / modulation unit 415 includes, for example, addition of a parity code for error correction and generation of a code string having an encoding rate that provides required characteristics. Then, encoding / modulation section 415 outputs a signal obtained by encoding and modulation to RF transmission circuit 416.

The RF transmission circuit 416 performs RF transmission processing of the signal output from the encoding / modulation unit 415. The RF transmission processing performed by the RF transmission circuit 416 includes, for example, conversion from digital to analog, frequency conversion, and the like. The RF transmission circuit 416 outputs a signal obtained by the RF transmission process to the transmission antenna 417. The transmission antenna 417 wirelessly transmits the signal output from the RF transmission circuit 416.

The receiving antenna 421 receives a signal wirelessly transmitted from another communication device (for example, a wireless communication terminal). Then, the reception antenna 421 outputs the received signal to the RF reception circuit 422. The RF reception circuit 422 performs an RF reception process on the signal output from the reception antenna 421. The RF reception processing performed by the RF reception circuit 422 includes, for example, frequency conversion and analog to digital conversion. The RF reception circuit 422 outputs a signal obtained by the RF reception process to the demodulation / decoding unit 423.

The demodulation / decoding unit 423 performs demodulation and decoding of the signal output from the RF reception circuit 422. Demodulation / decoding section 423 outputs a signal obtained by demodulation and decoding to demultiplexing section 424.

The demultiplexing unit 424 demultiplexes the signal output from the demodulation / decoding unit 423. Then, the demultiplexing unit 424 outputs each demultiplexed signal. Each signal output from the demultiplexing unit 424 includes, for example, PSS reception result report information, other control information, user data, and the like.

1A and 1B can be realized by an RF transmission circuit 416 and a transmission antenna 417, for example. The control unit 141 shown in FIGS. 1A and 1B can be realized by, for example, a control signal generation unit 411, a multiplexing unit 413, a multiplexing unit 414, an encoding / modulation unit 415, an RF transmission circuit 416, and a transmission antenna 417. it can. The receiving unit 142 illustrated in FIGS. 1A and 1B can be realized by, for example, the receiving antenna 421, the RF receiving circuit 422, the demodulation / decoding unit 423, and the demultiplexing unit 424.

(Terminal configuration)
FIG. 5A is a diagram illustrating an exemplary configuration of a terminal. FIG. 5B is a diagram illustrating an example of a signal flow in the configuration of the terminal illustrated in FIG. 5A. Each of first terminal 221 and second terminal 222 shown in FIGS. 2A to 2D can be realized by terminal 500 shown in FIGS. 5A and 5B, for example.

The terminal 500 includes a data signal generation unit 511, a control signal generation unit 512, a multiplexing unit 513, a PSS generation unit 514, a switch 515, an encoding / modulation unit 516, an RF transmission circuit 517, and a transmission antenna. 518. Terminal 500 includes a receiving antenna 521, an RF receiving circuit 522, a demodulation / decoding unit 523, a demultiplexing unit 524, and a PSS detection unit 525.

The data signal generation unit 511, the control signal generation unit 512, the multiplexing unit 513, the PSS generation unit 514, the switch 515, the encoding / modulation unit 516, the demodulation / decoding unit 523, the demultiplexing unit 524, and the PSS detection unit 525 are, for example, It can be realized by the LSI 501.

The data signal generation unit 511 generates a data signal for the terminal 500 to wirelessly transmit based on the input user data. Then, the data signal generation unit 511 outputs the generated data signal to the multiplexing unit 513.

The control signal generation unit 512 generates a control signal for the terminal 500 to wirelessly transmit. The control signal generated by the control signal generator 512 includes, for example, PSS reception result report information and other control information. The control signal generation unit 512 outputs the generated control signal to the multiplexing unit 513.

The multiplexing unit 513 multiplexes the input pilot signal (or reference signal), the data signal output from the data signal generation unit 511, and the control signal output from the control signal generation unit 512. Then, multiplexing section 513 outputs a signal obtained by multiplexing to switch 515.

When the PSS transmission instruction information is output from the demultiplexing unit 524, the PSS generation unit 514 generates a PSS based on the PSS transmission instruction information. Specifically, the PSS generator 514 generates a waveform pattern PSS based on the parameter u included in the transmission instruction information and the above equation (1). Then, the PSS generation unit 514 outputs the generated PSS to the switch 515. Further, when the PSS transmission stop instruction information is output from the demultiplexing unit 524, the PSS generation unit 514 stops generating the PSS.

The switch 515 time-multiplexes the signal output from the multiplexing unit 513 and the PSS output from the PSS generation unit 514 and outputs the result to the encoding / modulation unit 516.

The encoding / modulation unit 516 encodes and modulates the signal output from the switch 515. The encoding by the encoding / modulation unit 516 includes, for example, addition of a parity code for error correction, generation of a code string having an encoding rate that provides required characteristics, and the like. Then, encoding / modulation section 516 outputs a signal obtained by encoding and modulation to RF transmission circuit 517.

The RF transmission circuit 517 performs RF transmission processing on the signal output from the encoding / modulation unit 516. The RF transmission processing performed by the RF transmission circuit 517 includes, for example, digital-to-analog conversion and frequency conversion. The RF transmission circuit 517 outputs a signal obtained by the RF transmission process to the transmission antenna 518. The transmission antenna 518 wirelessly transmits the signal output from the RF transmission circuit 517.

The receiving antenna 521 receives a signal wirelessly transmitted from another communication device (for example, the base station 400). Then, the reception antenna 521 outputs the received signal to the RF reception circuit 522. The RF reception circuit 522 performs an RF reception process on the signal output from the reception antenna 521. The RF reception processing performed by the RF reception circuit 522 includes, for example, frequency conversion and analog to digital conversion. The RF reception circuit 522 outputs a signal obtained by the RF reception process to the demodulation / decoding unit 523 and the PSS detection unit 525.

The demodulator / decoder 523 demodulates and decodes the signal output from the RF receiver circuit 522. Demodulation / decoding section 523 outputs a signal obtained by demodulation and decoding to demultiplexing section 524.

The demultiplexing unit 524 demultiplexes the signal output from the demodulation / decoding unit 523. Then, the demultiplexing unit 524 outputs each demultiplexed signal. Each signal output from the demultiplexing unit 524 includes, for example, PSS transmission instruction information, PSS transmission stop instruction information, PSS detection instruction information, other control information, user data, and the like. The demultiplexing unit 524 outputs the PSS transmission instruction information and the PSS transmission stop instruction information to the PSS generation unit 514. Further, the demultiplexing unit 524 outputs PSS detection instruction information to the PSS detection unit 525.

The PSS detection unit 525 detects the PSS transmitted from the base station 400 from the signal output from the RF reception circuit 522. For example, the PSS detection unit 525 generates replica signals having a plurality of predetermined waveform patterns. Then, the PSS detection unit 525 detects the PSS transmitted as the measurement signal from the base station 400 by comparing the signal output from the RF reception circuit 522 with the replica signal.

Further, when the PSS detection instruction information is output from the demultiplexing unit 524, the PSS detection unit 525, among the signals output from the RF reception circuit 522, the PSS transmitted as a measurement signal from another terminal 500. Detection is performed. For example, the PSS detector 525 generates a replica signal of a waveform pattern based on the parameter u included in the detection instruction information and the above equation (1). Then, the PSS detection unit 525 detects the PSS transmitted from the other terminal 500 as the measurement signal by comparing the signal output from the RF reception circuit 522 with the replica signal. Then, PSS detection section 525 outputs report information of the PSS reception result based on the PSS detection result to control signal generation section 512.

1A and 1B can be realized by, for example, the reception antenna 521, the RF reception circuit 522, the demodulation / decoding unit 523, and the demultiplexing unit 524. 1A and 1B can be realized by, for example, a PSS generation unit 514, a switch 515, an encoding / modulation unit 516, an RF transmission circuit 517, and a transmission antenna 518.

1A and 1B can be realized by, for example, the reception antenna 521, the RF reception circuit 522, the demodulation / decoding unit 523, and the demultiplexing unit 524. 1A and 1B is implemented by, for example, a PSS detection unit 525, a control signal generation unit 512, a multiplexing unit 513, a switch 515, an encoding / modulation unit 516, an RF transmission circuit 517, and a transmission antenna 518. can do.

(Processing by base station)
FIG. 6 is a flowchart illustrating an example of processing by the base station. The base station 400 executes, for example, each step shown in FIG. First, the base station 400 determines whether or not the first terminal 221 and the second terminal 222 are in the same cell (step S601), and the first terminal 221 and the second terminal 222 are in the same cell. (Step S601: No loop).

In step S601, when the first terminal 221 and the second terminal 222 are in the same cell (step S601: Yes), the base station 400 determines the waveform pattern and transmission power of the PSS transmitted by the first terminal 221. (Step S602). In step S602, the base station 400 determines a waveform pattern orthogonal to the PSS waveform pattern transmitted from the own station as the PSS waveform pattern transmitted from the first terminal 221.

Next, the base station 400 transmits PSS transmission instruction information to the first terminal 221 (step S603). The transmission instruction information includes the waveform pattern determined in step S602 and the parameter u indicating the transmission power.

In addition, the base station 400 transmits the PSS detection instruction information from the first terminal 221 to the second terminal 222 (step S604). The detection instruction information includes the waveform pattern determined in step S602 and the parameter u indicating the transmission power. Note that the order of steps S603 and S604 may be changed.

Next, the base station 400 sets a timer for measuring a predetermined time (step S605). Next, the base station 400 determines whether or not PSS reception result report information has been received from the second terminal 222 (step S606). When the report information has not been received (step S606: No), the base station 400 determines whether or not the timer set in step S605 has expired (step S607). When the timer has not expired (step S607: No), the base station 400 returns to step S606.

In step S607, when the set timer expires (step S607: Yes), the base station 400 transmits PSS transmission stop instruction information to the first terminal 221 (step S608), and ends a series of processing. In this case, the base station 400 does not start processing for causing direct communication between the first terminal 221 and the second terminal 222.

In step S606, when report information is received (step S606: Yes), the base station 400 transmits PSS transmission stop instruction information to the first terminal 221 (step S609). Next, the base station 400 starts processing for direct communication between the first terminal 221 and the second terminal 222 based on the report information received in step S606 (step S610), and performs a series of processing. finish.

In the processing started in step S610, the base station 400 compares the communication quality between the first terminal 221 and the second terminal 222 based on the report information received in step S606 with a threshold value, for example. And if the communication quality is less than a threshold value, the base station 400 does not start direct communication between the first terminal 221 and the second terminal 222.

Moreover, if the communication quality is equal to or higher than the threshold, the base station 400 starts direct communication between the first terminal 221 and the second terminal 222 by transmitting a control signal to the first terminal 221 and the second terminal 222. Let The control signal transmitted from the base station 400 to the first terminal 221 and the second terminal 222 includes, for example, radio resources used for direct communication between the first terminal 221 and the second terminal 222, the start timing of direct communication, and the like. It is a signal to show.

(Processing by terminal)
FIG. 7 is a flowchart illustrating an example of processing by the terminal. The terminal 500 executes, for example, each step shown in FIG. First, terminal 500 determines whether or not PSS transmission instruction information has been received from base station 400 (step S701). If transmission instruction information has not been received (step S701: No), terminal 500 determines whether or not PSS detection instruction information has been received from base station 400 (step S702). If the detection instruction information has not been received (step S702: No), the terminal 500 returns to step S701.

In step S702, when the detection instruction information is received (step S702: Yes), the terminal 500 sets a timer for measuring a predetermined time (step S703). Next, terminal 500 determines whether or not a PSS based on the received detection instruction information has been received from another terminal (step S704). The PSS based on the detection instruction information is a PSS having a waveform pattern derived from the parameter u included in the detection instruction information.

In step S704, when the PSS based on the detection instruction information is not received (step S704: No), the terminal 500 determines whether or not the timer set in step S703 has expired (step S705). If the timer has not expired (step S705: No), the terminal 500 returns to step S704. If the timer has expired (step S705: Yes), the terminal 500 returns to step S701.

In step S704, when the PSS based on the detection instruction information is received (step S704: Yes), the terminal 500 transmits report information of the PSS reception result to the base station 400 (step S706). Then, terminal 500 ends a series of processes and waits for next instruction information from base station 400 (for example, returns to step S701).

In step S701, when transmission instruction information is received (step S701: Yes), terminal 500 starts transmission of PSS based on the received transmission instruction information (step S707). The PSS based on the transmission instruction information is a PSS having a waveform pattern derived from the parameter u included in the transmission instruction information.

Next, terminal 500 determines whether or not PSS transmission stop instruction information has been received from base station 400 (step S708), and waits until reception stop instruction information is received (step S708: No loop). When receiving the transmission stop instruction information (step S708: Yes), the terminal 500 stops the transmission of the PSS started in step S707 (step S709). Then, terminal 500 ends a series of processes and waits for next instruction information from base station 400 (for example, returns to step S701).

(Measurement operation in communication system)
FIG. 8 is a sequence diagram illustrating an example of a measurement operation in the communication system. As shown in FIG. 8, for example, first, base station 210 transmits PSS transmission instruction information including parameter u to first terminal 221 (step S801). In addition, the base station 210 transmits PSS detection instruction information including the parameter u to the second terminal 222 (step S802).

Next, the first terminal 221 starts periodic transmission of PSS based on the transmission instruction information transmitted in step S801. That is, the first terminal 221 transmits the PSS in accordance with the PSS transmission timing of the base station 210 (step S803). Then, the first terminal 221 transmits the PSS in accordance with the transmission timing next to the PSS of the base station 210 (step S804).

In the example shown in FIG. 8, it is assumed that the second terminal 222 transmits report information indicating the average value of the results of receiving two PSSs. In this case, the second terminal 222 detects each PSS transmitted in steps S803 and S804 based on the detection instruction information transmitted in step S802. Then, the second terminal 222 transmits report information indicating an average value of the detected reception results of each PSS to the base station 210 (step S805).

Thereby, the base station 210 can obtain the reception result at the second terminal 222 of the PSS transmitted from the first terminal 221. Next, the base station 210 transmits PSS transmission stop instruction information to the first terminal 221 (step S806).

(PSS transmission timing)
FIG. 9 is a diagram illustrating an example of PSS transmission timing. In FIG. 9, the horizontal axis represents time. As shown in FIG. 9, the base station 210 wirelessly transmits

PSSs

911, 912,... With a period of, for example, 5 [ms]. The transmission time of the PSS 911 is time t1. In the example shown in FIG. 9, the first terminal 221 receives PSS911 at time t1 + T2. The second terminal 222 receives the PSS 911 at time t1 + T3.

The first terminal 221 transmits the PSS 921 at the time t2 when 5 [ms] + ΔT has elapsed from the time t1 + T2 at which the PSS 911 is received. ΔT is set to be equal to or less than half the length of the guard interval (cyclic prefix) of

PSSs

911, 912,. For example, ΔT = 0 [ms] can be set. For example, ΔT is determined by the base station 210 and notified from the base station 210 to the first terminal 221.

PSS921 is a measurement signal having a waveform pattern orthogonal to PSS911, 912,... And the same frequency as PSS911, 912,. The second terminal 222 receives the PSS 921 almost simultaneously with the PSS 912, but the PSS 921 can detect the PSS 921 with high accuracy because the waveform pattern is orthogonal to the PSS 912.

(Determination of measurement signal transmission power)
An example of a method for determining the transmission power of the measurement signal by the base station 210 will be described.

FIG. 10 is a diagram illustrating an example of grouping of transmission powers of measurement signals. For example, the base station 210 may store the group information 1000 illustrated in FIG. 10 in a memory. In the group information 1000, each transmission power of the measurement signal (P1 <P2 <P3 <P4 <P5 <...) Is divided into “low”, “medium”, and “high” groups.

FIG. 11 is a flowchart showing an example of processing for determining the transmission power of a measurement signal. First, the base station 210 executes, for example, each step shown in FIG. First, the base station 210 acquires a path loss PL1 between the first terminal 221 and the base station 210 (step S1101). In addition, the base station 210 acquires a path loss PL2 between the second terminal 222 and the base station 210 (step S1102). Note that the order of steps S1101 and S1102 may be changed.

Next, the base station 210 determines whether interference suppression request information has been received from an adjacent base station (step S1103). If the request information has been received (step S1103: Yes), the base station 210 determines whether at least one of the path loss PL1 and PL2 acquired in steps S1101 and S1102 is greater than the threshold value Pth (step S1104). ). The threshold value Pth is a path loss that serves as a reference for determining whether or not the terminal is located near the cell edge.

In step S1104, when both the path loss PL1 and PL2 are equal to or smaller than the threshold value Pth (step S1104: No), the base station 210 proceeds to step S1105. That is, the base station 210 selects transmission power from the “medium” group in the group information 1000 shown in FIG. 10 (step S1105), and ends a series of determination processes.

In step S1104, when at least one of the path loss PL1 and PL2 is larger than the threshold value Pth (step S1104: Yes), the base station 210 moves to step S1106. That is, the base station 210 selects transmission power from the “low” group of the group information 1000 shown in FIG. 10 (step S1106), and ends a series of determination processes.

In step S1103, if the request information has not been received (step S1103: No), the base station 210 proceeds to step S1107. That is, the base station 210 determines whether or not at least one of the path losses PL1 and PL2 acquired in steps S1101 and S1102 is larger than the threshold value Pth (step S1107).

In step S1107, when both the path loss PL1 and PL2 are equal to or smaller than the threshold value Pth (step S1107: No), the base station 210 proceeds to step S1108. That is, the base station 210 selects transmission power from the “high” or “medium” group of the group information 1000 shown in FIG. 10 (step S1108), and ends a series of determination processes.

In step S1107, when at least one of path loss PL1 and PL2 is larger than threshold value Pth (step S1107: Yes), base station 210 moves to step S1109. That is, the base station 210 selects transmission power from the “low” or “medium” group in the group information 1000 shown in FIG. 10 (step S1109), and ends a series of determination processes.

The base station 210 determines the transmission power selected in any of steps S1105, S1106, S1108, and S1109 as the transmission power of the measurement signal. Thus, the base station 210 determines the transmission power of the measurement signal based on at least one of the path loss PL1 between the first terminal 221 and the path loss PL2 between the second terminal 222, for example. To do. The transmission power of the measurement signal can be determined according to the magnitude of the influence of the interference caused by the measurement signal.

As described above, according to the communication system, the control device, and the control method, communication quality can be measured while suppressing interference.

For example, in cellular communication, communication between wireless terminals is performed via a wireless base station. The radio base station controls radio resources used for radio communication with radio terminals and provides stable quality radio communication. When communication is performed between two wireless terminals, even if each wireless terminal is located at a short distance, communication between those terminals is established with each wireless base station. It is performed by wireless communication using a wireless line, and direct wireless communication between terminals is not performed.

Although communication via a radio base station is stable, radio resources of the radio base station are consumed, so communication between radio terminals located in a short distance is performed directly via a radio link established between these terminals. It may also be preferable to carry out by In particular, when these wireless terminals are located at a short distance from each other and are far from the wireless base station, it is considered particularly preferable from the viewpoint of consumption of wireless resources. This is because the amount of radio resources used to transmit data of a certain size increases as the distance from the radio base station increases.

By switching the communication between wireless terminals from the one via the base station to the direct wireless communication between the wireless terminals, the load of the wireless base station is reduced and the utilization efficiency of the wireless resources of the wireless base station is improved. It is thought that it can plan. However, direct wireless communication between wireless terminals may cause wireless interference to the wireless communication between the wireless base station and the wireless terminal, and may deteriorate the quality of normal communication. For this reason, when performing direct wireless communication between wireless terminals, one of the problems is to control interference caused by wireless signals transmitted from wireless terminals for direct communication between wireless terminals.

On the other hand, according to each of the above-described embodiments, among the signals transmitted by the base station, a signal having a good cross-correlation characteristic (a sufficiently low cross-correlation value can be obtained in practice) is transmitted on the terminal side. The terminal generates and transmits this as a measurement radio signal in accordance with the transmission timing of the base station. At this time, the parameter u is set so that it can be considered to be practically orthogonal to the signal output by the base station. Specifically, a radio signal having the same signal waveform format as that of a synchronization signal periodically transmitted from the radio base station in the radio downlink is transmitted to the terminal.

Thus, when determining whether or not direct communication between terminals is possible, the communication quality between terminals is measured by using a signal whose waveform pattern is orthogonal with the same resource as the synchronization signal of the base station. And interference with communication between wireless terminals can be suppressed.

DESCRIPTION OF SYMBOLS 100,200 Communication system 110 1st communication apparatus 111,122,132 Transmission part 120 2nd communication apparatus 121,131,142 Reception part 130 3rd communication apparatus 140 Control apparatus 141 Control part 210,400 Base station 221 1st terminal 222 Second terminal 223 Third terminal 300

Corresponding information

401, 501 LSI
411,512 Control signal generator 412 511 Data signal generator 413 414 513 Multiplexer 415 516 Encoder / Modulator 416 517 RF transmission circuit 417 518 Transmit antenna 421 521 Receive antenna 422 522

RF Reception circuit

423, 523 Demodulation /

decoding unit

424, 524 Demultiplexing unit 500 Terminal 514 PSS generation unit 515 Switch 525

PSS detection unit

911, 912, 921 PSS
1000 group information

Claims

A first communication device that wirelessly transmits a synchronization signal;
A second communication device and a third communication device, at least one of which is wirelessly connected to the first communication device and capable of directly communicating with each other;
The first communication device causes the second communication device to wirelessly transmit a measurement signal whose waveform pattern is orthogonal to the synchronization signal and has the same frequency band, and the reception result of the measurement signal in the third communication device Is received from the third communication device.
2. The communication system according to claim 1, wherein the measurement signal transmitted by the second communication device is wirelessly transmitted from the second communication device in accordance with a transmission timing of a synchronization signal transmitted by the first communication device.
The first communication device is a base station;
The second communication device and the third communication device are wireless communication terminals;
The communication system according to claim 1 or 2.
The first communication device is an eNodeB;
The second communication device and the third communication device are UEs;
The communication system according to any one of claims 1 to 3, wherein:
The first communication device notifies the second communication device and the third communication device of a parameter capable of deriving a waveform pattern orthogonal to the synchronization signal;
The second communication device wirelessly transmits the measurement signal based on the parameter notified by the first communication device;
The third communication device receives the measurement signal based on a parameter notified by the first communication device;
The communication system according to any one of claims 1 to 4, wherein:
The first communication device and the second communication device share correspondence information that associates the parameter with the transmission power of the measurement signal,
The first communication device determines a transmission power of the measurement signal, and selects a parameter corresponding to the determined transmission power from among parameters capable of deriving a waveform pattern orthogonal to the synchronization signal based on the correspondence information Notify the selected parameters,
The second communication device wirelessly transmits the measurement signal with a transmission power corresponding to the parameter notified by the first communication device based on the correspondence information.
The communication system according to claim 5.
The third communication device is
Share the correspondence information,
The transmission power corresponding to the parameter notified by the first communication device is identified based on the correspondence information, and the propagation loss of the measurement signal is calculated based on the identified transmission power and the reception power of the measurement signal And
Transmitting the reception result indicating the calculated propagation loss to the first communication device;
The communication system according to claim 6.
The first communication device is at least one of a propagation loss between the second communication device and the first communication device and a propagation loss between the third communication device and the first communication device. 8. The communication system according to claim 6, wherein the transmission power is determined based on the transmission power.
The correspondence information associates the parameter with a difference between a transmission power of a reference signal from the first communication device and a transmission power of the measurement signal. The communication system according to 1.
The communication system according to claim 9, wherein the reference signal is a CRS (Cell-Specific Reference Signal).
11. The communication system according to claim 10, wherein the reference signal is CSI RS (Channel State Information Reference Signal).
The second communication device transmits the measurement signal in synchronization with the transmission timing of the synchronization signal by the first communication device based on the timing at which the synchronization signal wirelessly transmitted from the first communication device is detected. The communication system according to any one of claims 1 to 11.
The first communication device starts direct communication between the second communication device and the third communication device according to a reception result received from the third communication device. The communication system according to any one of 12.
The first communication apparatus receives information indicating a path loss between the third communication apparatus and the first communication apparatus from the third communication apparatus together with the reception result. The communication system according to any one of the above.
The first communication device transmits, together with the reception result, information indicating a reception timing difference between a synchronization signal transmitted from the first communication device and a synchronization signal transmitted from the second communication device to the third communication. The communication system according to any one of claims 1 to 14, wherein the communication system is received from a device.
The first communication device receives information indicating a required signal power-to-noise interference power ratio with respect to a reference signal transmitted from the first communication device together with the reception result from the third communication device. Item 16. The communication system according to any one of Items 1 to 15.
The first communication apparatus receives, from the third communication apparatus, information indicating the wireless characteristics of each division unit when the wireless transmission band is divided into a plurality of parts together with the reception result. The communication system according to any one of the above.
The communication system according to any one of claims 1 to 17, wherein the first communication device receives the reception result by a PUSCH (Physical Uplink Shared Channel).
The communication system according to any one of claims 1 to 18, wherein the first communication device receives the reception result by a PUCCH (Physical Uplink Control Channel).
The first communication device displays the radio parameters of the channel that receives the reception result and the resource information of the channel used by the third communication device by using PDSCH (Physical Downlink Shared Channel), PDCCH (Physical Downlink Control Channel) or E 20. The communication system according to claim 18 or 19, wherein the third communication device is notified by PDCCH (Enhanced-Physical Downlink Control Channel).
The first communication device transmits the resource information of the PUSCH or PUCCH used by the third communication device together with the radio parameter of the channel receiving the reception result and the resource information of the channel used by the third communication device. 21. The communication system according to claim 20, wherein the third communication apparatus is notified by E-PDCCH.
The first communication device further notifies the third communication device by PDCCH or E-PDCCH of information indicating directly or indirectly that PUSCH or PUCCH is used for transmitting the reception result. The communication system according to claim 21.
A control device that controls the second communication device and the third communication device, at least one of which is wirelessly connected to the first communication device that wirelessly transmits the synchronization signal and capable of directly communicating with each other;
A control unit for wirelessly transmitting a measurement signal having a waveform pattern orthogonal to the synchronization signal and having the same frequency band from the second communication device in accordance with the transmission timing of the synchronization signal;
A receiving unit that receives, from the third communication device, a reception result of the measurement signal wirelessly transmitted from the second communication device by the control unit in the third communication device;
A control device comprising:
A control method for controlling a second communication device and a third communication device, at least one of which is wirelessly connected to a first communication device that wirelessly transmits a synchronization signal and capable of directly communicating with each other,
A measurement signal having a waveform pattern orthogonal to the synchronization signal and having the same frequency band is transmitted wirelessly from the second communication device in accordance with the transmission timing of the synchronization signal,
Receiving the reception result of the measurement signal in the third communication device from the third communication device;
A control method characterized by that.