Wireless communication device

Abstract

To provide a radio communication device that can properly relay radio waves according to the reception status of the radio waves.SOLUTION: A radio communication device 10 is a radio communication device that transmits re-radiated waves by relaying reception signals received from the outside and includes a branch part 111, a detection part 112, a control part 113, a signal amplification part, a terminal resistance 130 and a switch part 114. The branch part 111 divides the reception signal and generates the first branch signal and the second branch signal. The detection part 112 detects the reception signal power of the first branch signal. The control part 113 determines a transmission path of the second branch signal on the basis of the reception signal power and threshold information stored in a storage part 115 in advance. The signal amplification part amplifies the power value of the second branch signal. The terminal resistance 130 consumes the energy of the signal. The switch part 114 switches the transmission path of the second branch signal to the signal amplification part or the terminal resistance 130 on the basis of the result determined by the control part 113.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a wireless communication device.

Background Art

[0002] Conventionally, technologies have been proposed for relaying radio waves to create an area where wireless communication is possible with respect to radio wave dead zones that occur inside buildings, houses, etc. Patent Document 1 discloses a wireless relay device that adjusts signal power in a poor radio wave environment such as indoors to eliminate radio wave dead zones. The wireless relay device disclosed in Patent Document 1 adjusts signal power by an AGC (Automatic Gain Control) function that adjusts gain according to received power.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Even when the radio waves transmitted from the base station reach the target terminal sufficiently or when the received power in the wireless relay device is excessive, the wireless relay device disclosed in Patent Document 1 relays the radio waves, so that the radio waves to the transmission target terminal are not attenuated. Therefore, even when the radio wave arrival environment changes and improves, interference occurs between the direct wave transmitted from the base station to the target terminal and the re-radiated wave via the wireless relay device, and the reception quality deteriorates.

[0005] The present invention has been made in view of such problems of the conventional technology. An object of the present invention is to provide a wireless communication device capable of appropriately relaying radio waves according to the reception status of radio waves.

Means for Solving the Problems

[0006] A wireless communication device according to an aspect of the present invention is a wireless communication device that relays a received signal received from an external source and transmits a re-radiated wave, comprising: a branching unit that branches the received signal and generates a first branch signal and a second branch signal; a detection unit that detects the received signal power of the first branch signal; a control unit that determines the transmission path of the second branch signal based on the received signal power and threshold information stored in a storage unit; a signal amplification unit that amplifies the power value of the second branch signal; a termination resistor that consumes the signal energy; and a switch unit that switches the transmission path of the second branch signal to the signal amplification unit or the termination resistor based on the result determined by the control unit. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a wireless communication device that can appropriately relay radio waves according to the radio wave reception conditions. [Brief explanation of the drawing]

[0008] [Figure 1] This figure illustrates a configuration to which the wireless communication device according to this embodiment is applied. [Figure 2] This is a block diagram of the transmitter and receiver of the wireless communication device according to this embodiment. [Figure 3] This diagram shows the configuration of the wireless communication device according to this embodiment. [Figure 4] This is a diagram illustrating the threshold information according to this embodiment. [Figure 5] This diagram illustrates signal propagation loss in wireless communication devices. [Figure 6A] This diagram illustrates the power attenuation of signals in wireless communication devices. [Figure 6B] This diagram illustrates the power attenuation of signals in wireless communication devices. [Figure 7] This diagram illustrates the signal propagation loss in wireless communication devices when the radio wave arrival environment changes. [Figure 8]This figure illustrates the signal propagation loss in the wireless communication device according to this embodiment. [Modes for carrying out the invention]

[0009] The wireless communication device 10 according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios. In addition, in the following drawings, identical or similar parts are denoted by the same or similar reference numerals.

[0010] (Wireless communication device 10) Figure 1 shows the configuration of a communication system to which the wireless communication device 10 according to this embodiment is applied.

[0011] The power of radio waves transmitted wirelessly from base station 600 experiences increased spatial propagation loss as the carrier frequency increases. Therefore, the higher the frequency, the greater the power attenuation of the radio waves, and the narrower the area where communication is possible, resulting in areas where communication is disrupted (hereinafter referred to as dead zones).

[0012] The example shown in Figure 1 illustrates a situation where a dead zone may occur during wireless signal transmission from base station 600 to receiving terminal 700, potentially hindering direct wave communication. In Figure 1, the dead zone is schematically represented as DZ1. Furthermore, Figure 1 shows an example where the receiving terminal 700 is located within the dead zone DZ1.

[0013] Conventionally, as one of the means to eliminate this dead zone, an optical fiber wireless system (A-RoF: Analog-Radio over Fiber) has been used. The optical fiber wireless system receives the radio waves transmitted from the base station 600 at a place where they can be surely received, such as outdoors, photoelectrically converts the received signal, transmits the signal to a remote dead zone using an optical fiber cable, and then photoelectrically converts it again and re-radiates it to eliminate the dead zone. Note that the optical fiber cable applied in the optical fiber wireless system is characterized in that its propagation loss is extremely low compared to the spatial attenuation.

[0014] In FIG. 1, as an optical fiber wireless system, a wireless communication device 10 including a first transceiver 100, a second transceiver 200, a transmission line 300, a first antenna 400 on the side of the first transceiver 100, and a second antenna 500 on the side of the second transceiver 200 is shown.

[0015] Also, in the example shown in FIG. 1, the wireless communication device 10 receives the radio waves transmitted from the base station 600 to the receiving terminal 700 by the first transceiver 100 via the first antenna 400. Further, the wireless communication device 10 transmits the radio waves as re-radiated waves to the receiving terminal 700 via the second transceiver 200 and the second antenna 500. That is, the wireless communication device 10 relays the received signal received from the outside and transmits a re-radiated wave.

[0016] FIG. 2 is a block diagram showing an example of the configuration of the first transceiver 100 and the second transceiver 200 in the wireless communication device 10. In the example shown in FIG. 2, the first transceiver 100 shows a transmission-side function with respect to the transmission line 300. Also, in the example shown in FIG. 2, the second transceiver 200 shows a reception-side function with respect to the transmission line 300. When transmitting the radio waves received by the wireless communication device 10 to the base station 600, the first transceiver 100 and the second transceiver 200 may each perform a reception-side and a transmission-side function with respect to the transmission line 300 (not shown).

[0017] The first transceiver 100 includes a switching control unit 110, an optical I / F unit 120 (I / F: Interface), and a termination resistor 130. The details of the switching control unit 110 will be described later. Also, the second transceiver 200 includes a light receiving element 210, a bias tee 220, a power amplifier 230, and a band-pass filter 240.

[0018] The optical I / F unit 120 includes a low-noise amplifier 121, a band-pass filter 122, a bias tee 123, and a light emitting element 124.

[0019] The low-noise amplifier 121 amplifies the power of the signal while suppressing the noise generated by the amplifier itself. Also, the amplification of the signal power in the low-noise amplifier 121 serves to compensate for the conversion losses in the subsequent light emitting element 124 and light receiving element 210.

[0020] The band-pass filters 122 and 240 are filters that allow frequencies in a predetermined band to pass through the signal. <0​​​​​​​​​​The transmission line 300 is a single communication line connecting the first transceiver 100 and the second transceiver 200. An example of the transmission line 300 is an optical fiber. An optical fiber is made of, for example, glass or resin. An optical fiber is composed of, for example, a core layer through which optical signals propagate and a cladding layer surrounding the core layer. In an optical fiber, optical signals propagate within the core layer by total internal reflection at a predetermined angle at the interface between the core layer and the cladding layer. Optical fibers can have a smaller diameter than metal wires and can also be made lighter. Furthermore, optical fibers have extremely low propagation loss compared to spatial attenuation. Therefore, in this embodiment, the first transceiver 100 and the second transceiver 200 can be installed at locations physically separated by a predetermined distance. For example, by installing the first transceiver 100 in a location where radio waves can be reliably received, such as outdoors, and installing the second transceiver 200 in a dead zone, it is possible to transmit and re-radiate wireless signals and eliminate dead zones.

[0024] The photodetector 210 converts the optical signal received via the transmission line 300 into an electrical signal and sends it to the subsequent power amplifier 230. For example, a photodiode (PD) is used for the photodetector 210. In this embodiment, a configuration including a low-noise amplifier or a trans-impedance amplifier (TIA) may be applied between the photodetector 210 and the power amplifier 230.

[0025] The power amplifier 230 amplifies the signal so that the radio waves re-radiated from the second antenna 500 are equal to or greater than the minimum receive power that can be received by the receiving terminal 700. In other words, in this embodiment, the power amplifier 230 amplifies the signal power so that the power of the re-radiated waves transmitted to the receiving terminal 700 is higher than the minimum receive power at the receiving terminal 700. The minimum receive power at the receiving terminal 700 is a power value determined for each receiving terminal 700 or wireless communication standard, and is the power at which a signal can be accurately received and at which a certain coding error rate occurs. For example, if the receiving terminal 700 receives a signal with a power lower than the minimum receive power, the quality of that signal cannot be guaranteed at the receiving terminal 700.

[0026] The termination resistor 130 dissipates the energy of the high-frequency signal and prevents unwanted reflections of the signal.

[0027] Next, the switching control unit 110 of the wireless communication device 10 according to this embodiment will be described. Figure 3 is a block diagram showing the configuration of the switching control unit 110 according to this embodiment.

[0028] The switching control unit 110 is comprised of a branching unit 111, a detection unit 112, a control unit 113, a switch unit 114, and a storage unit 115.

[0029] The branching unit 111 branches the received signal and generates a first branch signal and a second branch signal. In this embodiment, the branching unit 111 is implemented by a general coupler, for example, as shown in Figure 3. In the example shown in Figure 3, the first branch signal corresponds to the signal sent from the branching unit 111 to the detection unit 112. In the example shown in Figure 3, the second branch signal corresponds to the signal that can be sent from the branching unit 111 to the switch unit 114. In this embodiment, the branching ratio in the generation of the first branch signal and the second branch signal by the branching unit 111 is assumed to be the same. That is, in this embodiment, the power of the first branch signal and the second branch signal is the same. Note that the configuration in which the branching ratio in the generation of the first branch signal and the second branch signal by the branching unit 111 is the same is not limited to the configuration of this embodiment. For example, if the branching ratio in the generation of the first branch signal and the second branch signal by the branching unit 111 is different, a configuration in which the input power is estimated by calculation according to the ratio may be applied. Furthermore, it is assumed that there is substantially no power loss in the generation of the first branch signal and the second branch signal by the branching unit 111.

[0030] The detection unit 112 detects the received signal power of the first branch signal. The detection unit 112 also sends information regarding the detected received signal power of the first branch signal to the subsequent control unit 113. The detection unit 112 is implemented by, for example, a general detector (power detector). In this embodiment, as described above, there is no substantial power loss at the branching unit 111, so the received signal power of the first branch signal corresponds to the power of the signal received by the wireless communication device 10.

[0031] The control unit 113 determines the transmission path of the second branch signal based on the received signal power and threshold information previously stored in the storage unit 115. The threshold information stored in the storage unit 115 includes, for example, information on "input power," information on "amplification," information on "interference information," information on "unwanted radiation," and information on "upper limit U," as shown in Figure 4. In this embodiment, the threshold information is calculated by the user based on previously measured interference information and unwanted radiation information according to the radio wave environment to which the wireless communication device 10 is applied, and stored in the storage unit 115.

[0032] The information regarding "input power" corresponds to the power value detected by the detection unit 112. In the example shown in Figure 4, the power at Pin 1 is the lowest, and the input power increases as you move downwards in the table shown in Figure 4.

[0033] The "amplification" information indicates the degree to which the power is amplified by the first transceiver 100 and the second transceiver 200 relative to the "input power". As described above, in the example shown in Figure 4, the input power of Pin1 is the lowest, and the input power increases as you move downwards in the table shown in Figure 4. Generally, in an amplifier, the amplification saturates as the power increases. Therefore, in the example shown in Figure 4, it is shown that the amplification decreases as the input power increases.

[0034] The "interference" information indicates whether or not the direct wave and the re-radiated wave interfere with each other. When the amplification of the input power decreases, interference may occur between the power of the direct wave at the receiving terminal 700 and the re-radiated wave with reduced amplification. For example, in the example shown in Figure 4, it is shown that interference between the direct wave and the re-radiated wave occurs when the input power is Pin 4 or higher. In other words, the threshold information includes "interference" information, which indicates whether or not interference occurs between the re-radiated wave and the direct wave.

[0035] Information regarding "unwanted radiation" indicates whether or not unwanted radiation, a type of noise, is generated by the re-radiated wave. In other words, threshold information includes information regarding "unwanted radiation," which indicates whether or not unwanted radiation is generated by the re-radiated wave. For example, when the input power exceeds a predetermined value, intermodulation distortion occurs due to a decrease in the linearity of the amplification factor, which may result in unwanted radiation. For example, in the example shown in Figure 4, it is shown that unwanted radiation occurs when the input power is Pin 5 or higher.

[0036] The information regarding "Upper Limit U" indicates the upper limit (boundary) of the power value when no interference or unwanted radiation occurs with respect to the input power. In other words, the threshold information includes information regarding "Upper Limit U," which is the upper limit of the input power when no interference or unwanted radiation occurs between the re-radiated wave and the direct wave.

[0037] Furthermore, the information stored in "Upper Limit U" may include a value exceeding the upper limit (boundary) of the power value when no interference or unwanted radiation occurs. For example, in the example shown in Figure 4, interference occurs at Pin 4, so Upper Limit U is shown as Pin 4. In this case, the effective upper limit of power when no interference or unwanted radiation occurs is a value less than "Upper Limit U," and it is indicated that interference or unwanted radiation occurs at values ​​of "Upper Limit U" or higher. In other words, in this embodiment, when the input power exceeds the upper limit, interference or unwanted radiation occurs between the re-radiated wave and the direct wave in the wireless communication device 10.

[0038] Returning to the explanation of the control unit 113, the control unit 113 determines whether the received signal power detected by the detection unit 112 is greater than the upper limit value U of the threshold information stored in the storage unit 115. In this embodiment, if the control unit 113 determines that the power detected by the detection unit 112 is greater than or equal to the upper limit value U, it controls the subsequent switch unit 114 so that the transmission path of the second branch signal goes to the termination resistor 130. On the other hand, if the control unit 113 determines that the power detected by the detection unit 112 is less than the upper limit value U, it controls the subsequent switch unit 114 so that the transmission path of the second branch signal goes to the signal amplification unit.

[0039] In this embodiment, the "signal amplification unit" corresponds to a configuration including the optical I / F unit 120 of the first transceiver 100, the transmission line 300, and the second transceiver 200. The first amplification unit corresponds to the optical I / F unit 120 of the first transceiver 100. The second amplification unit corresponds to the second transceiver 200.

[0040] Based on the result determined by the control unit 113, the switch unit 114 switches the transmission path of the second branch signal to either the signal amplifier or the termination resistor 130. In this embodiment, the switch unit 114 is composed of a general RF switch (Radio Frequency). RF switches are used to switch signal paths in high-frequency circuits within wireless communication devices.

[0041] Figure 5 is a diagram illustrating the operation of the wireless communication device 10 in this embodiment. First, in the example shown in Figure 5, the propagation loss of power as a direct wave when the radio waves received at the position of the first antenna 400 are transmitted to the receiving terminal 700 without amplification will be explained using points A to D. In the examples shown in Figures 5, 7, and 8, the power transition of the direct wave is represented by a solid line, and the power transition of the re-radiated wave is represented by a dashed line.

[0042] First, the power of the signal received at point A experiences propagation loss of Lp1 between point A and point B, where there is an obstruction. Furthermore, propagation loss of Lin occurs at the obstruction between point B and point C. In addition, propagation loss of Lp2 occurs between point C, where there is an obstruction, and point D, where the receiving terminal 700 is located. In other words, the power at point D of the receiving terminal 700 is reduced by Lin1 + Lin + Lin2 due to propagation loss from the power at point A. As shown in Figure 5, the received power at point D is lower than the minimum received power, so the location where the receiving terminal 700 is installed is a dead zone where the direct wave cannot be properly received.

[0043] Next, the re-radiation by the wireless communication device 10 in this embodiment will be described. In the example shown in Figure 5, the power transition of the signal amplified by the wireless communication device 10 is shown at points A and E to H. Note that the example of re-radiation shown in Figure 5 is an example in which the control unit 113 determines that the input power is less than the upper limit value U.

[0044] First, the signal received by the first antenna 400 is amplified in power up to point E by the low-noise amplifier 121 of the optical I / F section 120 of the first transceiver 100. Then, the optical signal is sent to the second transceiver 200 via the transmission line 300. For example, in the example shown in Figure 5, the signal power decreases from point E to point F due to propagation loss in the optical fiber and loss due to photoelectric conversion. In the second transceiver 200, after photoelectric conversion by the photodetector 210, the power is amplified by the power amplifier 230 from point F to point G as shown in Figure 5. Then, the signal is transmitted to the receiving terminal 700 via the second antenna 500. In the example shown in Figure 5, point H indicates the power of the re-radiated wave at the receiving terminal 700. Also, in the example shown in Figure 5, there is a predetermined power difference between point D, which is the received power of the direct wave at the receiving terminal 700, and point H, which is the received power of the re-radiated wave, and this example shows that no interference occurs.

[0045] Figures 6A and 6B show the relationship between spatial propagation loss (attenuation) and distance for a 28 GHz radio wave. For example, as shown in Figure 6A, the change in attenuation at short distances is greater than the change in attenuation at long distances. This spatial propagation loss is given by the following equation (1). In equation (1) below, "Loss" represents the spatial propagation loss (dB), r represents the distance (m), and λ represents the wavelength of the propagating signal (m). Loss=20×Log(4πr / λ) ··· (1)

[0046] For example, in the example shown in Figure 5, since the signal is transmitted over a predetermined distance in the transmission path 300 of the wireless communication device 10, the distance from the second antenna 500 to the receiving terminal 700 is shorter than the distance from the obstacle to the receiving terminal 700. Therefore, in the example shown in Figure 5, the slope of the line showing the power propagation loss from point G to point H is greater than the slope of the line showing the power propagation loss from point C to point D.

[0047] Figure 7 shows an example where the power received by the first antenna 400 increases due to environmental changes, such as an increase in the received signal strength of the radio waves transmitted from the base station 600. In the example shown in Figure 7, the transition of the direct wave power when the power received by the first antenna 400 increases due to this change in the radio wave reception environment is shown from point A2 to point D2. That is, in the example shown in Figure 7, point D2, which is the power of the direct wave received by the receiving terminal 700 due to the environmental change, is greater than the minimum received power.

[0048] As a comparative example of how the radio wave reception environment changes, points A2 and E2-H2 show the power changes of the re-radiated wave when the power of the received signal is amplified in a conventional wireless communication system. As shown in Figure 7, when the power at point A2, which represents the received power at the first antenna 400, increases, the amplification decreases, and point H2, which represents the power of the re-radiated wave at the receiving terminal 700, is shown to be close to point D2. This means that when the received power at the first antenna 400 is high, there is a risk of interference occurring between the direct wave and the re-radiated wave. Also, when the received power at the first antenna 400 is high, there is a risk of unwanted radiation of the re-radiated wave due to the decrease in amplification.

[0049] Therefore, in this embodiment, if the received power at the first antenna 400 is high, the switching control unit 110 described above will not transmit the re-radiated waves from the wireless communication device 10.

[0050] Specifically, in the wireless communication device 10, the branching unit 111 of the switching control unit 110 first branches the received signal at the branching unit 111 to generate a first branch signal and a second branch signal. The detection unit 112 also detects the received signal power of the first branch signal. Furthermore, the control unit 113 determines that the received signal power of the first branch signal detected by the detection unit 112 is equal to or greater than the upper limit value U of the threshold information stored in the storage unit 115, and controls the switch unit 114 to set the transmission path of the second branch signal to the termination resistor 130. As a result, if the received power at the first antenna 400 is high, the received signal (second branch signal) is sent to the termination resistor 130, and re-radiation of propagation is not performed.

[0051] Figure 8 shows an example of the power transition of a transmitted signal when the received power at the first antenna 400 is high. As shown in Figure 8, the power of the signal received by the first antenna 400 is at point A2, which is greater than point U, which indicates the upper limit. Therefore, the power of the direct wave transitions as shown from point A2 to point D2, and point D2, received at the receiving terminal 700, is greater than the minimum received power. Also, since point A2 of the power received by the first antenna 400 is greater than point U, which indicates the upper limit, the transmission of re-radiated waves in the wireless communication device 10 is not performed. Therefore, in the example shown in Figure 8, there are no re-radiated waves, and no interference between the direct wave and the re-radiated wave occurs. Also, since the transmission of re-radiated waves in the wireless communication device 10 does not occur, no unwanted radiation of re-radiated waves occurs. As a result, the wireless communication device 10 can relay radio waves appropriately according to the radio wave reception conditions.

[0052] As described above, the wireless communication device 10 according to this embodiment is a wireless communication device that relays a received signal received from an external source and transmits a re-radiated wave, and comprises a branching unit 111, a detection unit 112, a control unit 113, a signal amplification unit, a termination resistor 130, and a switch unit 114. The branching unit 111 branches the received signal and generates a first branch signal and a second branch signal. The detection unit 112 detects the received signal power of the first branch signal. The control unit 113 determines the transmission path of the second branch signal based on the received signal power and threshold information stored in advance in the storage unit 115. The signal amplification unit amplifies the power value of the second branch signal. The termination resistor 130 consumes the signal energy. The switch unit 114 switches the transmission path of the second branch signal to either the signal amplification unit or the termination resistor 130 based on the result determined by the control unit 113.

[0053] As a result, the wireless communication device 10 can amplify power according to the received radio wave strength and relay the radio waves appropriately. For example, conventionally, devices that relay radio waves refer to the radio wave strength from broadcast information in the signal transmitted from the base station or from the received information RSSI (Received Signal Strength Indicator) of the receiving terminal. The wireless communication device 10 according to this embodiment makes it possible to relay radio waves appropriately without installing a modem chip or the like, and without demodulating the communication content (information). Furthermore, the wireless communication device 10 can be used in relay devices that do not have a modem chip (for example, RoF: Radio on Fiber). In addition, since the wireless communication device 10 does not need to demodulate the received signal when relaying radio waves, it enables low-latency communication relay.

[0054] Furthermore, the signal amplification section of the wireless communication device 10 may include a first amplification section that amplifies power while suppressing noise generated by the amplifier itself, and a second amplification section that amplifies the signal power so that the power of the re-radiated wave transmitted to the receiving terminal is higher than the minimum received power at the receiving terminal 700. The first amplification section corresponds to the optical I / F section 120 of the first transceiver 100. The second amplification section corresponds to the second transceiver 200.

[0055] As a result, when the wireless communication device 10 transmits a re-radiated wave with amplified power to the receiving terminal 700, it can transmit a re-radiated wave with a power higher than the minimum received power at the receiving terminal 700.

[0056] Furthermore, the signal amplification unit of the wireless communication device 10 may include a transmission line 300 connected to the first amplification unit and the second amplification unit, which has less power loss than spatial propagation. The wireless communication device 10 receives the radio waves transmitted from the base station 600 at a location where it can be reliably received, converts the received signal photoelectrically, transmits the signal to a distant dead zone using the transmission line 300, converts it photoelectrically again, and re-radiates it. In this way, the wireless communication device 10 can eliminate dead zones at the receiving terminal 700.

[0057] Furthermore, the threshold information may include information indicating whether or not interference occurs between the re-radiated wave and the direct wave, information indicating whether or not unwanted radiation occurs from the re-radiated wave, and an upper limit value U indicating the upper limit of the input power when no interference with the direct wave or unwanted radiation occurs with respect to the input power of the received signal. In addition, the control unit 113 of the wireless communication device 10 may control the switch unit 114 so that the transmission path of the second branch signal becomes the signal amplification unit when it determines that the received signal power is less than the upper limit value U. As a result, when the wireless communication device 10 determines that the power of the received signal is less than the upper limit value U, it can transmit a re-radiated wave that does not cause interference with the direct wave or unwanted radiation to the receiving terminal 700.

[0058] Furthermore, the control unit 113 of the wireless communication device 10 may control the switch unit 114 so that the transmission path of the second branch signal becomes a terminating resistor when it determines that the received signal power is above the upper limit. In this way, when the wireless communication device 10 does not transmit a re-radiated wave, it can switch the path of the received signal to the terminating resistor 130, consume the energy of the received signal, and prevent unwanted reflection of the signal.

[0059] (Other embodiments) While embodiments have been described in detail with reference to the drawings, these embodiments are not limited to those described above. Furthermore, the components described above include those easily conceivable by those skilled in the art, and those that are substantially the same. Moreover, the configurations described above can be combined as appropriate. In addition, various omissions, substitutions, or modifications of the configurations can be made without departing from the spirit of the embodiments.

[0060] The features of the wireless communication device 10 are described below.

[0061] The wireless communication device 10 according to the first embodiment is a wireless communication device that relays a received signal received from an external source and transmits a re-radiated wave, and comprises a branching unit 111, a detection unit 112, a control unit 113, a signal amplification unit, a termination resistor 130, and a switch unit 114. The branching unit 111 branches the received signal and generates a first branch signal and a second branch signal. The detection unit 112 detects the received signal power of the first branch signal. The control unit 113 determines the transmission path of the second branch signal based on the received signal power and threshold information stored in advance in the storage unit 115. The signal amplification unit amplifies the power value of the second branch signal. The termination resistor 130 consumes the signal energy. The switch unit 114 switches the transmission path of the second branch signal to the signal amplification unit or the termination resistor 130 based on the result determined by the control unit 113.

[0062] With the above configuration, the wireless communication device 10 can perform power amplification according to the radio wave reception conditions and relay radio waves appropriately. For example, conventionally, in devices that relay radio waves, the radio wave strength is referenced from broadcast information in the signal transmitted from the base station or from the RSSI reception information of the receiving terminal. The wireless communication device 10 according to this embodiment makes it possible to relay radio waves appropriately without installing a modem chip or the like, and without demodulating the communication content (information). Furthermore, the wireless communication device 10 can be used in relay devices that do not have a modem chip (for example, RoF: Radio on Fiber). In addition, since the wireless communication device 10 does not need to demodulate the received signal when relaying radio waves, it enables low-latency communication relay.

[0063] The signal amplification unit of the wireless communication device 10 according to the second embodiment may include a first amplification unit that amplifies power while suppressing noise generated by the amplifier itself, and a second amplification unit that amplifies the signal so that the power of the re-radiated wave transmitted to the receiving terminal is higher than the minimum received power at the receiving terminal 700.

[0064] According to the above configuration, when the wireless communication device 10 transmits a re-radiated wave with amplified power to the receiving terminal 700, it can transmit a re-radiated wave with a power higher than the minimum received power at the receiving terminal 700 to the receiving terminal 700.

[0065] The signal amplification section of the wireless communication device 10 according to the third embodiment may include a transmission line 300 that connects the first amplification section and the second amplification section and has less power loss than spatial propagation.

[0066] According to the above configuration, the wireless communication device 10 can receive radio waves transmitted from the base station 600 at a location where it can be reliably received, convert the received signal photoelectrically, transmit the signal to a distant dead zone using the transmission path 300, and then convert it photoelectrically again and re-radiate it. As a result, the wireless communication device 10 can eliminate dead zones at the receiving terminal 700.

[0067] The threshold information relating to the fourth embodiment may include information indicating whether or not interference occurs between the re-radiated wave and the direct wave, and information indicating whether or not unwanted radiation of the re-radiated wave occurs. The threshold information may also include an upper limit value U indicating the upper limit of the input power of the received signal when no interference with the direct wave and no unwanted radiation occur. Furthermore, the control unit 113 of the wireless communication device 10 may control the switch unit 114 so that the transmission path of the second branch signal becomes the signal amplification unit when it determines that the received signal power is less than the upper limit value U.

[0068] According to the above configuration, if the wireless communication device 10 determines that the power of the received signal is less than the upper limit value U, it will be able to transmit a re-radiated wave to the receiving terminal 700 that does not interfere with the direct wave or cause unwanted radiation.

[0069] In the fifth embodiment, the control unit 113 of the wireless communication device 10 may control the switch unit 114 so that the transmission path of the second branch signal becomes a terminating resistor when it determines that the received signal power is above an upper limit.

[0070] According to the above configuration, when the wireless communication device 10 does not transmit re-radiated waves, it can switch the path of the received signal to the termination resistor 130, thereby consuming the energy of the received signal and preventing unwanted reflection of the signal. [Explanation of Symbols]

[0071] 10 Wireless communication devices 100 First Transmitter / Receiver 110 Switching control unit 111 Branching point 112 Detection unit 113 Control Unit 114 Switch section 115 Storage section 120 Optical I / F section 130 Termination resistor 200 Second Transmitter / Receiver 300 transmission lines

Claims

1. A wireless communication device that relays a received signal received from an external source and transmits a re-radiated wave, A branching unit that branches the received signal and generates a first branch signal and a second branch signal, A detection unit for detecting the received signal power of the first branch signal, A control unit that determines the transmission path of the second branch signal based on the received signal power and threshold information stored in the storage unit in advance, A signal amplification unit that amplifies the power value of the second branch signal, A termination resistor that consumes signal energy, A wireless communication device comprising: a switch unit that switches the transmission path of the second branch signal to the signal amplification unit or the termination resistor based on the result determined by the control unit.

2. The wireless communication device according to claim 1, wherein the signal amplification unit comprises a first amplification unit that amplifies power while suppressing noise generated by the amplifier itself, and a second amplification unit that amplifies the power of the signal such that the power of the re-radiated wave transmitted to the receiving terminal is higher than the minimum received power at the receiving terminal.

3. The wireless communication device according to claim 2, wherein the signal amplification unit connects the first amplification unit and the second amplification unit and includes a transmission path that has less power loss than spatial propagation.

4. The threshold information includes information indicating whether or not interference occurs between the re-radiated wave and the direct wave, and information indicating whether or not unwanted radiation occurs from the re-radiated wave, and an upper limit value indicating the upper limit of the input power when no interference with the direct wave and no unwanted radiation occur with respect to the input power of the received signal. The wireless communication device according to any one of claims 1 to 3, wherein the control unit controls the switch unit so that the transmission path of the second branch signal becomes the signal amplification unit when it determines that the received signal power is less than the upper limit.

5. The wireless communication device according to claim 4, wherein the control unit controls the switch unit so that the transmission path of the second branch signal becomes the termination resistor when it determines that the received signal power is equal to or greater than the upper limit.

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