Wireless repeater, wireless repeating method, and computer program

Abstract

To contribute to miniaturization, weight saving, or power saving, for a radio repeater in a TDD radio communication system.SOLUTION: A radio repeater for repeating a signal transmitted / received between a terminal and a base station in a TDD radio communication system includes a control part for changing over between a downlink repeating period for repeating a signal transmitted from the base station to the terminal and an uplink repeating period for repeating a signal transmitted from the terminal to the base station based on a change of reception power in an uplink direction from the terminal to the base station. The control part detects the downlink repeating period based on a change of reception power in a downlink direction from the base station to the terminal, executes change-over between the downlink repeating period and the uplink repeating period based on the detected downlink repeating period, then, executes change-over between the downlink repeating period and the uplink repeating period based on the change of the reception power in the uplink direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a wireless repeater, a wireless repeating method, and a computer program. [Background technology]

[0002] Conventionally, there is known a wireless repeater that relays signals transmitted and received between a terminal and a base station in a TDD (Time Division Duplex) wireless communication system (see, for example, Patent Documents 1, 2, and 3). In a TDD wireless communication system, signals from the terminal to the base station (uplink) and signals from the base station to the terminal (downlink) use the same frequency, so that bidirectional communication is performed between the terminal and the base station by switching between an uplink transmission period and a downlink transmission period in a time division manner. In a TDD wireless communication system, a wireless repeater receives and amplifies each of the uplink and downlink signals before transmitting them.

[0003] In the technique described in Patent Document 1, a wireless repeater receives and demodulates a downstream signal transmitted from a base station to detect a TDD frame, thereby recognizing the downstream and upstream transmission periods. In the technology described in Patent Document 2, a wireless repeater receives a downlink signal transmitted from a base station, and detects a TDD frame from the correlation result between the received downlink signal and a reference signal with a frame period generated by the wireless repeater, thereby recognizing the downlink and uplink transmission periods. In the technology described in Patent Document 3, a wireless repeater receives a downlink signal transmitted from a base station, detects the preamble of the received downlink signal, and performs frame synchronization using the detected preamble, thereby recognizing the downlink and uplink transmission periods. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-15790 A [Patent Document 2] Patent No. 4572236 [Patent Document 3] JP 2010-93586 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technologies described in the above-mentioned Patent Documents 1, 2, and 3, it is necessary to demodulate the downlink received signal transmitted from the base station, to correlate the downlink received signal with a reference signal, and to detect a preamble from the downlink received signal, which results in a wireless repeater with a complex and large-scale circuit configuration and high power consumption. This poses the problem that it is difficult to make the wireless repeater smaller, lighter, and more energy-efficient.

[0006] The present invention has been made in consideration of the above circumstances, and has an object to contribute to reducing the size, weight, and power consumption of wireless repeaters in TDD wireless communication systems. [Means for solving the problem]

[0007] (1) One aspect of the present invention is a wireless repeater that relays signals transmitted and received between a terminal and a base station in a TDD (Time Division Duplex) wireless communication system, and includes a control unit that switches between a downlink relay period in which a signal transmitted from the base station is relayed to the terminal and an uplink relay period in which a signal transmitted from the terminal is relayed to the base station based on a change in received power in the uplink direction from the terminal to the base station, wherein the control unit detects the downlink relay period based on a change in received power in the downlink direction from the base station to the terminal, switches between the downlink relay period and the uplink relay period based on the detected downlink relay period, and then switches between the downlink relay period and the uplink relay period based on the change in received power in the uplink direction. (2) One aspect of the present invention is a wireless repeater as described above in (1), wherein, when the received power in the uplink direction is below a predetermined threshold, the control unit switches between the downlink relay period and the uplink relay period based on a change in the received power in the downlink direction, instead of switching between the downlink relay period and the uplink relay period based on a change in the received power in the downlink direction. (3) One aspect of the present invention is a wireless repeater of either (1) or (2) above, wherein the control unit comprises: a counter unit that repeatedly counts at a predetermined count frequency from a predetermined count initial value to a predetermined count end value corresponding to a frame period of the TDD system; a switching timing detection unit that stores an uplink relay start timing count value, which is the count value of the counter unit at a timing when the uplink received power indicates a change from no signal to signal presence, and an uplink relay end timing count value, which is the count value of the counter unit at a timing when the uplink received power indicates a change from signal presence to no signal presence; and a switching control signal generation unit that generates a switching control signal for switching between the downlink relay period and the uplink relay period based on the uplink relay start timing count value, the uplink relay end timing count value, and the count value of the counter unit. (4) One aspect of the present invention is the wireless repeater of (3) above, wherein the switching timing detection unit further stores a downlink relay start timing count value, which is the count value of the counter unit at the timing when the downlink received power indicates a change from no signal to signal presence, and a downlink relay end timing count value, which is the count value of the counter unit at the timing when the downlink received power indicates a change from signal presence to no signal, and the switching control signal generation unit generates a switching control signal for switching between the downlink relay period and the uplink relay period based on the uplink relay start timing count value, the uplink relay end timing count value, the downlink relay start timing count value, the downlink relay end timing count value and the count value of the counter unit.

[0008] (5) One aspect of the present invention is a wireless relay method performed by a wireless repeater that relays signals transmitted and received between a terminal and a base station in a TDD (Time Division Duplex) wireless communication system, the wireless relay method including the steps of: detecting a downlink relay period during which a signal transmitted from the base station is relayed to the terminal based on a change in received power in the downlink direction from the base station to the terminal; switching between the downlink relay period and an uplink relay period during which a signal transmitted from the terminal is relayed to the base station based on the detected downlink relay period; and switching between the downlink relay period and the uplink relay period based on a change in received power in the uplink direction from the terminal to the base station.

[0009] (6) One aspect of the present invention is a computer program that realizes a control function in a computer of a wireless repeater that relays signals transmitted and received between a terminal and a base station in a TDD (Time Division Duplex) wireless communication system, switching between a downlink relay period in which a signal transmitted from the base station is relayed to the terminal and an uplink relay period in which a signal transmitted from the terminal is relayed to the base station based on a change in received power in the uplink direction from the terminal to the base station, the control function detecting the downlink relay period based on a change in received power in the downlink direction from the base station to the terminal, switching between the downlink relay period and the uplink relay period based on the detected downlink relay period, and then switching between the downlink relay period and the uplink relay period based on the change in received power in the uplink direction. Effect of the Invention

[0010] According to the present invention, it is possible to obtain an effect of contributing to miniaturization, weight reduction, and power saving of a wireless repeater in a TDD wireless communication system. [Brief description of the drawings]

[0011] [Figure 1] 1 is a block diagram showing an example of the configuration of a wireless communication system according to an embodiment; [Diagram 2]FIG. 2 is a block diagram showing a configuration example of a wireless repeater according to an embodiment. [Diagram 3] 1 is a flowchart illustrating an example of a procedure of a wireless relay method according to an embodiment. [Figure 4] 4 is an example of a switching timing chart according to an embodiment. [Diagram 5] FIG. 2 is a diagram illustrating an example of the configuration of a TDD frame according to an embodiment. [Figure 6] FIG. 2 is a block diagram illustrating an example of a wireless repeater according to an embodiment. [Figure 7] FIG. 4 is a block diagram showing an example of the configuration of a control unit according to an embodiment. [Figure 8] 1 is a schematic configuration diagram illustrating an example of a wireless communication system according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing an example of the configuration of a wireless communication system according to an embodiment. The wireless communication system 1 shown in Fig. 1 is a TDD (Time Division Duplex) system. Therefore, in the wireless communication system 1, an uplink signal (uplink signal) UL from the terminal UE to the base station BS and a downlink signal (downlink signal) DL from the base station BS to the terminal UE use the same frequency, and bidirectional communication is performed between the terminal UE and the base station BS by switching between an uplink transmission period and a downlink transmission period in a time division manner.

[0013] In the wireless communication system 1, the wireless repeater 10 receives and amplifies an uplink signal UL and a downlink signal DL, and then transmits them.

[0014] 2 is a block diagram showing an example of the configuration of a wireless repeater according to the present embodiment. In FIG. 2, the wireless repeater 10 includes a base station corresponding antenna 11, a terminal corresponding antenna 12, a downlink relay processing unit 13, an uplink relay processing unit 14, TDD switching units SW1 and SW2, and a control unit 20.

[0015] The base station corresponding antenna 11 is an antenna for receiving radio signals transmitted from the base station BS and for transmitting radio signals to the base station BS.

[0016] The terminal corresponding antenna 12 is an antenna for receiving radio signals transmitted from the terminal UE and for transmitting radio signals to the terminal UE.

[0017] The downstream relay processing unit 13 amplifies the downstream signal DL received via the base station corresponding antenna 11 and then transmits it via the terminal corresponding antenna 12 .

[0018] The upstream relay processing unit 14 amplifies the upstream signal UL received via the terminal corresponding antenna 12 and then transmits it via the base station corresponding antenna 11 .

[0019] The TDD switching unit SW1 switches whether the base station corresponding antenna 11 is connected to the downstream relay processing unit 13 or the upstream relay processing unit 14.

[0020] When the TDD switching unit SW1 selects the downlink relay processing unit 13, the base station corresponding antenna 11 is connected to the downlink relay processing unit 13. As a result, the downlink relay processing unit 13 receives the downlink signal DL via the base station corresponding antenna 11.

[0021] On the other hand, when the TDD switching unit SW1 selects the uplink relay processing unit 14, the base station corresponding antenna 11 is connected to the uplink relay processing unit 14. As a result, the uplink relay processing unit 14 transmits the uplink signal UL via the base station corresponding antenna 11.

[0022] The TDD switching section SW2 switches between connecting the terminal corresponding antenna 12 to the downstream relay processing section 13 or the upstream relay processing section 14.

[0023] When the TDD switching unit SW2 selects the downlink relay processing unit 13, the terminal corresponding antenna 12 is connected to the downlink relay processing unit 13. As a result, the downlink relay processing unit 13 transmits the downlink signal DL via the terminal corresponding antenna 12.

[0024] On the other hand, when the TDD switching unit SW2 selects the upstream relay processing unit 14, the terminal corresponding antenna 12 is connected to the upstream relay processing unit 14. As a result, the upstream relay processing unit 14 receives the upstream signal UL via the terminal corresponding antenna 12.

[0025] The control unit 20 controls the switching of the TDD switching units SW1 and SW2. The control unit 20 receives an uplink reception power signal A indicating the reception power of the uplink signal UL (reception power in the uplink direction) from the uplink relay processing unit 14. The control unit 20 also receives a downlink reception power signal B indicating the reception power of the downlink signal DL (reception power in the downlink direction) from the downlink relay processing unit 13.

[0026] The control unit 20 generates a switching control signal C based on the uplink reception power signal A and the downlink reception power signal B. The switching control signal C is a control signal for switching between a downlink relay period in which a downlink signal DL transmitted from the base station BS is relayed to the terminal UE, and an uplink relay period in which an uplink signal UL transmitted from the terminal UE is relayed to the base station.

[0027] A switching control signal C is input to the TDD switching units SW1 and SW2. The TDD switching units SW1 and SW2 select the relay processing units 13 and 14 to be connected to the antennas 11 and 12, respectively, in accordance with the switching control signal C.

[0028] The TDD switching unit SW1 connects the base station corresponding antenna 11 to the downlink relay processing unit 13 when the switching control signal C indicates a downlink relay period, and connects the base station corresponding antenna 11 to the uplink relay processing unit 14 when the switching control signal C indicates an uplink relay period. The TDD switching unit SW2 connects the terminal corresponding antenna 12 to the downlink relay processing unit 13 when the switching control signal C indicates a downlink relay period, and connects the terminal corresponding antenna 12 to the uplink relay processing unit 14 when the switching control signal C indicates an uplink relay period.

[0029] Therefore, when the switching control signal C indicates a downlink relay period, the downlink relay processing unit 13 amplifies the downlink signal DL received via the base station corresponding antenna 11 and transmits it via the terminal corresponding antenna 12. On the other hand, when the switching control signal C indicates a downlink relay period, the uplink relay processing unit 14 amplifies the uplink signal UL received via the terminal corresponding antenna 12 and transmits it via the base station corresponding antenna 11. This realizes two-way communication between the terminal UE and the base station BS in the TDD system.

[0030] Next, a wireless relay method according to this embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a flowchart showing an example of the procedure of the wireless relay method according to this embodiment. Fig. 4 is an example of a switching timing chart according to this embodiment.

[0031] (Step S1) When the control process of Fig. 3 is started, the control unit 20 first outputs a switching control signal C indicating a downlink relay period (first stage in Fig. 4). The TDD switching unit SW1 connects the base station corresponding antenna 11 to the downlink relay processing unit 13 in accordance with the switching control signal C. The TDD switching unit SW2 connects the terminal corresponding antenna 12 to the downlink relay processing unit 13 in accordance with the switching control signal C. As a result, in the first stage shown in Fig. 4, the downlink relay processing unit 13 amplifies the downlink signal DL received via the base station corresponding antenna 11 and then transmits it via the terminal corresponding antenna 12. The terminal UE receives the downlink signal DL via the wireless repeater 10.

[0032] (Step S2) The control unit 20 detects a change in the downlink reception power based on the downlink reception power signal B input from the downlink relay processing unit 13. Next, the control unit 20 detects a downlink relay period based on the change in the downlink reception power.

[0033] (Step S3) Based on the downlink relay period detected in step S2, the control unit 20 generates a switching control signal C. This switching control signal C is a signal that switches between the downlink relay period and the uplink relay period based on the downlink relay period detected in step S2.

[0034] (Step S4) The control unit 20 judges whether the generation of the switching control signal C in step S3 is successful or not. This judgment is made based on the trial result of trying (outputting to the TDD switching units SW1 and SW2) the switching control signal C a predetermined number of times. For example, in the multiple trials of the switching control signal C, the downlink reception power during the downlink relay period is averaged, and if this average value is equal to or greater than a predetermined threshold, it is judged as successful, and if not, it is judged as failed. Similarly, the uplink reception power may be averaged during the uplink relay period, and if this average value is equal to or greater than a predetermined threshold, it is judged as successful, and if not, it is judged as failed. Also, if the average value of the downlink reception power and the average value of the uplink reception power are equal to or greater than their respective thresholds, it may be judged as successful, and if not, it may be judged as failed.

[0035] If the result of the determination in step S4 is success, the process proceeds to step S5, whereas if the result is failure, the process returns to step S2.

[0036] (Step S5) The control unit 20 outputs the switching control signal C generated in step S3 to the TDD switching units SW1 and SW2 to control switching between the downlink relay period and the uplink relay period (second stage in FIG. 4). The TDD switching units SW1 and SW2 select the relay processing units 13 and 14 to be connected to the antennas 11 and 12 in accordance with the switching control signal C. This causes switching between the downlink relay period and the uplink relay period in the second stage shown in FIG. 4. In the downlink relay period, the downlink relay processing unit 13 amplifies the downlink signal DL received via the base station corresponding antenna 11 and then transmits it via the terminal corresponding antenna 12, and the terminal UE receives the downlink signal DL via the wireless repeater 10.

[0037] (Step S6) The control unit 20 detects a change in the uplink reception power based on the uplink reception power signal A input from the uplink relay processing unit 14 (third stage in FIG. 4). Next, the control unit 20 detects an uplink relay period based on the change in the uplink reception power. In the third stage shown in FIG. 4, the terminal UE demodulates the downlink signal DL received via the radio repeater 10 to detect a TDD frame, and transmits an uplink signal UL in the uplink transmission period based on the detected TDD frame. The transmission period of the uplink signal UL transmitted by the terminal UE is an accurate timing in the TDD system. Therefore, the uplink relay period detected by the control unit 20 based on the change in the uplink reception power is an accurate uplink relay period in the TDD system.

[0038] (Step S7) The control unit 20 generates a switching control signal C based on the uplink relay period detected in step S6 (third stage in FIG. 4). This switching control signal C is a signal that switches between the uplink relay period and the downlink relay period based on the uplink relay period detected in step S6.

[0039] (Step S8) The control unit 20 outputs the switching control signal C generated in step S7 to the TDD switching units SW1 and SW2 to control switching between the downlink relay period and the uplink relay period (third stage in FIG. 4). As a result, in the third stage shown in FIG. 4, switching is performed between the downlink relay period and the uplink relay period. In the downlink relay period, the downlink relay processing unit 13 amplifies the downlink signal DL received via the base station corresponding antenna 11 and transmits it via the terminal corresponding antenna 12, and the terminal UE receives the downlink signal DL via the wireless repeater 10. In the uplink relay period, the uplink relay processing unit 14 amplifies the uplink signal UL received via the terminal corresponding antenna 12 and transmits it via the base station corresponding antenna 11, and the base station BS receives the uplink signal UL via the wireless repeater 10.

[0040] (Step S9) If the control process of FIG. 3 is to be ended, the control process is ended, and if not, the process returns to step S6.

[0041] In addition, the control unit 20 may generate the switching control signal C based on both the change in the uplink reception power and the change in the downlink reception power in the third stage in Fig. 4. For example, when the uplink reception power is equal to or less than a predetermined threshold, the control unit 20 may switch between the downlink relay period and the uplink relay period based on the change in the downlink reception power, instead of switching between the downlink relay period and the uplink relay period based on the change in the uplink reception power.

[0042] Fig. 5 is a diagram showing an example of the configuration of a TDD frame. Fig. 5 shows a TDD frame used in the 3.5 GHz band of an LTE (Long Term Evolution) system, a TDD frame used in the 3.7 GHz band of a fifth generation mobile communication system (5G), and a TDD frame used in the 28 GHz band of a fifth generation mobile communication system (5G). All three types of TDD frames shown in Fig. 5 have a frame period (frame cycle) of 5 mS (5 milliseconds).

[0043] The configuration of a TDD frame used in the wireless communication system 1 is preset in the wireless repeater 10. When the wireless communication system 1 is, for example, a TDD scheme in the 3.5 GHz band of the LTE system, the configuration of a TDD frame in the 3.5 GHz band of the LTE system shown in FIG. 5 is preset in the wireless repeater 10.

[0044] The control unit 20 generates a switching control signal C based on a TDD frame configuration (periodicity of each transmission period of the downlink signal DL and the uplink signal UL) preset in the wireless repeater 10. The control unit 20 repeatedly generates the same switching control signal C with a frame period based on the TDD frame configuration preset in the wireless repeater 10.

[0045] Next, an example of the wireless repeater 10 according to the present embodiment will be described. Fig. 6 is a block diagram showing an example of the wireless repeater 10 according to the present embodiment. In Fig. 6, parts corresponding to those in Fig. 2 are given the same reference numerals.

[0046] In the wireless repeater 10 shown in Fig. 6, the radio frequency used on the base station side is different from the radio frequency used on the terminal side. The radio frequency used on the base station side is in the millimeter wave band. The radio frequency used on the terminal side is in the terahertz band. Therefore, the wireless repeater 10 receives the uplink signal UL and the downlink signal DL, converts the frequency of each of them, amplifies them, and then transmits them.

[0047] The base station compatible antenna (mmWANT) 11 is an antenna for receiving millimeter wave band radio signals transmitted from the base station BS, and for transmitting millimeter wave band radio signals to the base station BS.

[0048] The terminal corresponding antenna (THzBFANT) 12 is an antenna for receiving a terahertz band radio signal transmitted from the terminal UE, and for transmitting a terahertz band radio signal to the terminal UE.

[0049] The downstream relay processing unit 13 (coupler 13-1, variable attenuator 13-2, upconverter 13-3, bandpass filter 13-4, power amplifier 13-5) frequency converts (upconverts) the millimeter wave band downstream signal DL received via the base station compatible antenna 11 to the terahertz band, amplifies it, and then transmits it via the terminal compatible antenna 12.

[0050] The upstream relay processing unit 14 (coupler 14-1, variable attenuator 14-2, downconverter 14-3, bandpass filter 14-4, power amplifier 14-5) frequency converts (downconverts) the terahertz band upstream signal UL received via the terminal-compatible antenna 12 to the millimeter wave band, amplifies it, and then transmits it via the base station-compatible antenna 11.

[0051] The PLL_15 generates a clock signal for frequency conversion. The clock signal generated by the PLL_15 is supplied to the up-converter 13-3 and the down-converter 14-3.

[0052] The TDD switching unit (TDD SW) SW1 switches whether the base station corresponding antenna 11 is connected to the downstream relay processing unit 13 (the input unit of the coupler 13-1) or to the upstream relay processing unit 14 (the output unit of the power amplifier 14-5) in accordance with a switching control signal C output from the control unit 20.

[0053] The TDD switching unit (TDD SW) SW2 switches whether the terminal corresponding antenna 12 is connected to the downstream relay processing unit 13 (the output unit of the power amplifier 13-5) or to the upstream relay processing unit 14 (the input unit of the coupler 14-1) in accordance with a switching control signal C output from the control unit 20.

[0054] The control unit 20 receives an upstream reception power signal A from the upstream relay processing unit 14 (a branch of the coupler 14-1). The control unit 20 also receives a downstream reception power signal B from the downstream relay processing unit 13 (a branch of the coupler 13-1). The control unit 20 generates a switching control signal C based on the upstream reception power signal A and the downstream reception power signal B. The switching control signal C is output to the TDD switching units SW1 and SW2.

[0055] Fig. 7 is a block diagram showing a configuration example of the control unit 20 shown in Fig. 6. Of the units shown in Fig. 6, the function of the dashed line portion 220 may be realized by a microcomputer included in the wireless repeater 10 executing software (computer program), or may be realized by hardware.

[0056] An upstream reception power signal A is input to the detector 201a. This upstream reception power signal A is an upstream signal UL in the terahertz band branched by the coupler 14-1 of the upstream relay processing unit 14. The detector 201a detects the upstream reception power signal A (upstream signal UL in the terahertz band) to obtain an upstream reception signal level.

[0057] The downstream reception power signal B is input to the detector 201b. This downstream reception power signal B is a downstream signal DL in the millimeter wave band branched by the coupler 13-1 of the downstream relay processing unit 13. The detector 201b detects the downstream reception power signal B (downstream signal DL in the millimeter wave band) to obtain a downstream reception signal level.

[0058] 6, a detector may be used to input the received signal levels as the received power signals A and B to the control unit 20. In this case, the detectors 201a and 201b are not required.

[0059] The level adjuster 202a adjusts the signal level by amplifying or attenuating the signal so that the average value of the uplink reception signal level obtained by the detector 201a becomes a predetermined value. This makes it possible to correct the change in the uplink reception signal level according to the distance between the wireless repeater 10 and the terminal UE.

[0060] The level adjuster 202b adjusts the signal level by amplifying or attenuating the signal so that the average value of the downstream reception signal level obtained by the detector 201b becomes a predetermined value. This makes it possible to correct the change in the downstream reception signal level according to the distance between the wireless repeater 10 and the base station BS.

[0061] The level comparator 203a compares the level of the uplink reception signal after the level correction with a predetermined uplink level judgment threshold, and outputs an uplink level judgment signal indicating whether the uplink reception signal level is higher than the uplink level judgment threshold. The uplink level judgment threshold is a value selected from values ​​between the signal level of the uplink signal UL in a signal presence period and the signal level of the no-signal period. The reception power of the uplink signal UL transmitted from the terminal UE changes from weak power to strong power at the start timing of the transmission period of the uplink signal UL of the TDD frame, and changes from strong power to weak power at the end timing of the transmission period of the uplink signal UL of the TDD frame. The uplink level judgment threshold is a threshold for detecting this change (presence or absence of the uplink signal UL).

[0062] The level comparator 203b compares the level of the downlink reception signal after the level correction with a predetermined downlink level judgment threshold, and outputs a downlink level judgment signal indicating whether the downlink reception signal level is higher than the downlink level judgment threshold. The downlink level judgment threshold is a value selected from values ​​between the signal level of the signal period and the signal level of the no-signal period for the downlink signal DL. The reception power of the downlink signal DL transmitted from the base station BS changes from weak power to strong power at the start timing of the transmission period of the downlink signal DL of the TDD frame, and changes from strong power to weak power at the end timing of the transmission period of the downlink signal DL of the TDD frame. The downlink level judgment threshold is a threshold for detecting this change (presence or absence of the downlink signal DL).

[0063] Each level judgment signal output by each level comparator 203a, 203b may be a signal equivalent to a digital signal of "1: above level judgment threshold" and "0: below level judgment threshold". Also, by providing two types of threshold levels for each level judgment threshold, level judgment with hysteresis characteristics may be performed. This makes it possible to suppress errors in the output of the level comparator caused by noise contained in the received signal level.

[0064] The upward level judgment signal output from the level comparator 203 a and the downward level judgment signal output from the level comparator 203 b are output to a switching timing detection section 222 .

[0065] The clock generator 210 generates a clock signal at an integer fraction of the minimum time step required for the TDD switching units SW1 and SW2 to switch the connection destinations of the antennas 11 and 12 (switch between the uplink repeat period and the downlink repeat period). The frequency of the clock signal corresponds to the count frequency.

[0066] Counter 221 counts the clock signal generated by clock generator 210. Counter 221 is reset for each frame period of the TDD frame. Therefore, counter 221 starts counting from an initial count value of "0", and when the count value reaches a count number corresponding to one period of the TDD frame, the count value is reset to the initial value of "0" and then counting resumes.

[0067] For example, the frame period is 5 ms in the 3.5 GHz band TDD frame of the LTE system shown in Fig. 5. In this case, if the minimum time step for switching the connection destination of each of the antennas 11 and 12 by the TDD switching units SW1 and SW2 is 1 µS (1 microsecond), and the period of the clock signal generated by the clock generator 210 is 1 µS, that is, the clock oscillation frequency is 1 MHz (1 megaHz), the counter 221 counts from the count initial value "0" to the count end value "4999", and then is reset to the count initial value "0" and restarts counting.

[0068] The count value of the counter 221 is input to the switching timing detection unit 222. Furthermore, each level determination signal output from each level comparator 203a, 203b is input to the switching timing detection unit 222. Here, for convenience of explanation, each level determination signal is "1: exceeding level determination threshold" or "0: equal to or less than level determination threshold."

[0069] The switching timing detector 222 stores the count value (uplink relay start timing count value) at the timing when the uplink level determination signal output from the level comparator 203a changes from "0" to "1." The count value at that timing (uplink relay start timing count value) indicates the start of the uplink relay period.

[0070] Furthermore, the switching timing detector 222 stores the count value (uplink relay end timing count value) at the timing when the uplink level determination signal output from the level comparator 203a changes from "1" to "0." The count value at that timing (uplink relay end timing count value) indicates the end of the uplink relay period.

[0071] The uplink relay end timing count value may be a value obtained by adding a count number corresponding to the length of the transmission period of the uplink signal UL to the uplink relay start timing count value. The length of the transmission period of the uplink signal UL is included in the configuration of the TDD frame preset in the wireless repeater 10. The upstream relay start timing count value may be a value obtained by subtracting a count number equivalent to the length of the transmission period of the upstream signal UL from the upstream relay end timing count value.

[0072] The switching timing detector 222 stores the count value (downstream relay start timing count value) at the timing when the downstream level determination signal output from the level comparator 203b changes from "0" to "1." The count value at that timing (downstream relay start timing count value) indicates the start of the downstream relay period.

[0073] Furthermore, the switching timing detector 222 stores the count value (downstream relay end timing count value) at the timing when the downstream level determination signal output from the level comparator 203b changes from "1" to "0." The count value at that timing (downstream relay end timing count value) indicates the end of the downstream relay period.

[0074] The downstream relay end timing count value may be a value obtained by adding a count number corresponding to the length of the transmission period of the downstream signal DL to the downstream relay start timing count value. The length of the transmission period of the downstream signal DL is included in the configuration of the TDD frame preset in the wireless repeater 10. Also, the downstream relay start timing count value may be a value obtained by subtracting a count number equivalent to the length of the transmission period of the downstream signal DL from the downstream relay end timing count value.

[0075] The switching timing detection section 222 outputs the upstream relay start timing count value, the upstream relay end timing count value, the downstream relay start timing count value, and the downstream relay end timing count value to the switching control signal generation section 223 .

[0076] Note that the average values ​​of the uplink relay start timing count value, the uplink relay end timing count value, the downlink relay start timing count value and the downlink relay end timing count value may be stored in the switching timing detection unit 222 a predetermined number of times and output to the switching control signal generation unit 223. This makes it possible to reduce the influence of timing fluctuations that occur in the output timing of each level determination signal from each level comparator 203a, 203b due to a decrease in the reception level, noise, fading, etc.

[0077] The count value of the counter 221 is input to the switching control signal generator 223. In addition, the switching control signal generator 223 also receives an upstream relay start timing count value, an upstream relay end timing count value, a downstream relay start timing count value, and a downstream relay end timing count value output by the switching timing detector 222.

[0078] The switching control signal generator 223 generates a switching control signal C based on the count value of the counter 221, the uplink relay start timing count value, the uplink relay end timing count value, the downlink relay start timing count value, and the downlink relay end timing count value. An example of a method for generating this switching control signal is shown below.

[0079] (Example 1 of a method for generating a switching control signal) The switching control signal generator 223 first outputs a switching control signal C indicating a downstream relay period (first stage in FIG. 4). Next, the switching control signal generator 223 outputs a switching control signal C generated based on the count value of the counter 221, the downstream relay start timing count value, and the downstream relay end timing count value (second stage in FIG. 4). This switching control signal C starts the downstream relay period when the count value of the counter 221 matches the downstream relay start timing count value, and ends the downstream relay period when the count value of the counter 221 matches the downstream relay end timing count value.

[0080] Next, when the uplink signal UL is received, the switching control signal generator 223 outputs a switching control signal C generated based on the count value of the counter 221, the uplink relay start timing count value, and the uplink relay end timing count value (third stage in FIG. 4). This switching control signal C starts an uplink relay period when the count value of the counter 221 matches the uplink relay start timing count value, and ends the uplink relay period when the count value of the counter 221 matches the uplink relay end timing count value.

[0081] (Example 2 of a method for generating a switching control signal) The switching control signal generator 223 first outputs a switching control signal C indicating a downstream relay period (first stage in FIG. 4). Next, the switching control signal generator 223 outputs a switching control signal C generated based on the count value of the counter 221, the downstream relay start timing count value, and the downstream relay end timing count value (second stage in FIG. 4). This switching control signal C starts the downstream relay period when the count value of the counter 221 matches the downstream relay start timing count value, and ends the downstream relay period when the count value of the counter 221 matches the downstream relay end timing count value.

[0082] Next, when the uplink signal UL is received, the switching control signal generator 223 outputs a switching control signal C generated based on the count value of the counter 221 and the uplink relay start timing count value, the uplink relay end timing count value, the downlink relay start timing count value, and the downlink relay end timing count value (third stage in FIG. 4). This switching control signal C starts the uplink relay period when the count value of the counter 221 matches the median between the downlink relay start timing count value and the uplink relay end timing count value, and ends the uplink relay period when the count value of the counter 221 matches the median between the downlink relay end timing count value and the uplink relay start timing count value.

[0083] (Example 3 of a method for generating a switching control signal) 4 in the above-described switching control signal generating method, when the received power of the uplink signal UL (uplink received signal level after level correction by the level adjuster 202a) is equal to or lower than a predetermined threshold, the switching control signal generating unit 223 outputs a switching control signal C generated based on the count value of the counter 221, the downlink relay start timing count value, and the downlink relay end timing count value. This switching control signal C starts a downlink relay period at the timing when the count value of the counter 221 matches the downlink relay start timing count value, and ends the downlink relay period at the timing when the count value of the counter 221 matches the downlink relay end timing count value.

[0084] (Example 4 of a method for generating a switching control signal) 4 in the above-described example 2 of the switching control signal generating method, when the received power of the downlink signal DL (downlink received signal level after level correction by level adjuster 202b) is equal to or lower than a predetermined threshold, the switching control signal generating unit 223 outputs a switching control signal C generated based on the count value of counter 221, the uplink relay start timing count value, and the uplink relay end timing count value. This switching control signal C starts an uplink relay period at the timing when the count value of counter 221 matches the uplink relay start timing count value, and ends the uplink relay period at the timing when the count value of counter 221 matches the uplink relay end timing count value.

[0085] (Example 5 of a method for generating a switching control signal) In example 5 of the switching control signal generating method, in the third stage in FIG. 4 of example 1 or example 2 of the switching control signal generating method described above, when both the received power of the uplink signal UL (uplink received signal level after level correction by level adjuster 202a) and the received power of the downlink signal DL (downlink received signal level after level correction by level adjuster 202b) are below their respective predetermined thresholds, the switching control signal generating unit 223 outputs a switching control signal C generated based on the count value of the counter 221 and the relay start timing count value and relay end timing count value of either the uplink or downlink that are preset.

[0086] According to the above-mentioned example 3 and example 4 of the switching control signal generating method, it is possible to avoid using the timing detection result (each timing count value) including a large detection error in the timing of the start or end of the signal period, which occurs when the received signal level of either the uplink signal UL or the downlink signal DL is equal to or lower than a predetermined threshold, for generating the switching control signal C. This makes it possible to suppress deterioration in the accuracy of the switching control signal C.

[0087] According to this embodiment, the downlink relay period and the uplink relay period are switched based on the change in the uplink reception power. The transmission period of the uplink signal UL transmitted by the terminal UE is an accurate timing in the TDD system. Therefore, by switching between the downlink relay period and the uplink relay period based on the change in the uplink reception power, it is possible to accurately switch between the downlink relay period and the uplink relay period in the TDD system.

[0088] As a result, the wireless repeater 10 can accurately switch between the downlink repeating period and the uplink repeating period in the TDD system without using a complex and large-scale demodulation circuit, by using a configuration that detects changes in received power that are small and feasible compared to a demodulation circuit. This has the effect of contributing to the miniaturization, weight reduction, and power saving of the wireless repeater 10 in the TDD wireless communication system 1.

[0089] Fig. 8 is a schematic diagram showing an example of a wireless communication system 1 according to this embodiment. In the wireless communication system 1 shown in Fig. 8, the radio frequency used on the base station side is different from the radio frequency used on the terminal side. The radio frequency used on the base station side is in the millimeter wave band. The radio frequency used on the terminal side is in the terahertz band.

[0090] In the wireless communication system 1 shown in FIG. 8, the wireless repeater 10 of FIG. 6 according to this embodiment can be mounted on various devices DVa, DVb, DVc, DVd, and DVe. Device DVa is glasses worn by a user (terminal user) of the terminal UE. Device DVb is a vehicle in which the terminal user rides. Device DVc is headphones worn by the terminal user. Device DVd is a wristwatch worn by the terminal user. Device DVe is a portable personal computer (PC) used by the terminal user.

[0091] The wireless repeater 10 is provided, for example, in glasses (device DVa) worn by a terminal user. The terminal UE includes an antenna 301 for transmitting and receiving wireless signals in the terahertz band, and a signal processing unit 302 for processing received signals in the terahertz band. The signal processing unit 302 demodulates a downstream signal DL in the terahertz band received by the antenna 301 via the wireless repeater 10 provided in the glasses (device DVa) to detect a TDD frame, and transmits an upstream signal UL in the terahertz band from the antenna 301 during an upstream transmission period based on the detected TDD frame. A link THz LINK in the terahertz band is established between the terminal UE and the wireless repeater 10 provided in the glasses (device DVa). The wireless repeater 10 provided in the glasses (device DVa) transmits and receives an upstream signal UL and a downstream signal DL in the millimeter wave band to and from the base station BS. The wireless repeater 10 provided in the glasses (device DVa) receives the uplink signal UL and the downlink signal DL, converts the frequency of the signals, amplifies the signals, and then transmits them. This allows the terminal UE and the base station BS to perform two-way communication in the TDD system via the wireless repeater 10.

[0092] Here, for example, in small devices such as glasses (device DVa), headphones (device DVc), and wristwatches (device DVd), there are significant restrictions on the size, weight, battery capacity, and other factors of the equipment that can be mounted. For these small devices DVa, DVc, and DVd, there is a particular demand for the mounted wireless repeater 10 to be small, lightweight, and power-saving. This embodiment provides particularly significant effects when the wireless repeater 10 is mounted on such small devices DVa, DVc, and DVd.

[0093] This will make it possible to improve the overall service quality in wireless communication systems, for example, and thereby contribute to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0094] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not deviate from the gist of the present invention are also included.

[0095] In addition, a computer program for implementing the functions of each of the above-mentioned devices may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed. Note that the "computer system" referred to here may include hardware such as an OS and peripheral devices. In addition, the term "computer-readable recording medium" refers to writable non-volatile memory such as a flexible disk, an optical magnetic disk, a ROM, or a flash memory, a portable medium such as a DVD (Digital Versatile Disc), or a storage device such as a hard disk built into a computer system.

[0096] Furthermore, the term "computer-readable recording medium" includes devices that retain a program for a certain period of time, such as volatile memory (e.g., DRAM (Dynamic Random Access Memory)) within a computer system that serves as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. The program may be transmitted from a computer system in which the program is stored in a storage device or the like to another computer system via a transmission medium, or by a transmission wave in the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for implementing some of the functions described above, or may be a so-called differential file (differential program) that can implement the functions described above in combination with a program already recorded in the computer system. [Explanation of symbols]

[0097] 1... wireless communication system, UE... terminal, BS... base station, 10... wireless repeater, 11... base station compatible antenna, 12... terminal compatible antenna, 13... downstream relay processing unit, 14... upstream relay processing unit, SW1, SW2... TDD switching unit, 20... control unit, 201a, 201b... detector, 202a, 202b... level adjuster, 203a, 203b... level comparator, 210... clock generator, 221... counter, 222... switching timing detection unit, 223... switching control signal generation unit

Claims

1. A wireless repeater that relays signals transmitted and received between a terminal and a base station in a TDD (Time Division Duplex) wireless communication system, a control unit for switching between a downlink relay period in which a signal transmitted from the base station is relayed to the terminal and an uplink relay period in which a signal transmitted from the terminal is relayed to the base station, based on a change in reception power in an uplink direction from the terminal to the base station; the control unit detects the downlink relay period based on a change in downlink reception power from a base station to a terminal, switches between the downlink relay period and the uplink relay period based on the detected downlink relay period, and then switches between the downlink relay period and the uplink relay period based on the change in the uplink reception power; When the uplink reception power is equal to or less than a predetermined threshold, the control unit switches between the downlink relay period and the uplink relay period based on a change in the downlink reception power, instead of switching between the downlink relay period and the uplink relay period based on a change in the uplink reception power. Radio repeater.

2. The control unit is a counter unit that repeatedly counts from a predetermined count initial value to a predetermined count end value corresponding to a frame period of the TDD system at a predetermined count frequency; a switching timing detection unit that stores an uplink relay start timing count value, which is a count value of the counter unit at a timing when the uplink reception power indicates a change from no signal to a signal, and an uplink relay end timing count value, which is a count value of the counter unit at a timing when the uplink reception power indicates a change from a signal to no signal; a switching control signal generating unit that generates a switching control signal for switching between the downlink relay period and the uplink relay period based on the uplink relay start timing count value, the uplink relay end timing count value, and the count value of the counter unit.

2. The wireless repeater according to claim 1.

3. the switching timing detection unit further stores a downlink relay start timing count value, which is a count value of the counter unit at a timing when the downlink reception power indicates a change from no signal to a signal presence, and a downlink relay end timing count value, which is a count value of the counter unit at a timing when the downlink reception power indicates a change from a signal presence to no signal, the switching control signal generating unit generates a switching control signal for switching between the downlink relay period and the uplink relay period based on the uplink relay start timing count value, the uplink relay end timing count value, the downlink relay start timing count value, the downlink relay end timing count value, and a count value of the counter unit.

3. The wireless repeater according to claim 2.

4. A wireless relay method implemented by a wireless repeater that relays signals transmitted and received between a terminal and a base station in a wireless communication system using a TDD (Time Division Duplex) method, comprising the steps of: detecting a downlink relay period in which a signal transmitted from a base station is relayed to a terminal based on a change in downlink reception power from the base station to the terminal; a step of switching between the downlink relay period and an uplink relay period for relaying a signal transmitted from a terminal to a base station based on the detected downlink relay period; switching between the downlink relay period and the uplink relay period based on a change in reception power in an uplink direction from a terminal to a base station; when the uplink reception power is equal to or less than a predetermined threshold, switching between the downlink relay period and the uplink relay period based on a change in the downlink reception power, instead of switching between the downlink relay period and the uplink relay period based on a change in the uplink reception power; A wireless relay method comprising:

5. In a wireless communication system using a Time Division Duplex (TDD) method, a wireless repeater computer relays signals transmitted and received between a terminal and a base station. A control function is realized for switching between a downlink relay period in which a signal transmitted from a base station is relayed to a terminal and an uplink relay period in which a signal transmitted from the terminal is relayed to the base station, based on a change in the reception power in the uplink direction from the terminal to the base station; the control function detects the downlink relay period based on a change in downlink reception power from a base station to a terminal, switches between the downlink relay period and the uplink relay period based on the detected downlink relay period, and then switches between the downlink relay period and the uplink relay period based on the change in the uplink reception power; When the uplink reception power is equal to or less than a predetermined threshold, the control function performs switching between the downlink relay period and the uplink relay period based on a change in the downlink reception power, instead of switching between the downlink relay period and the uplink relay period based on a change in the uplink reception power. Computer program.

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