JP2017139599A - Mobile router, communication method of mobile router and program for implementing communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile router capable of lowering power consumption, and to provide a communication method of the mobile router, and a program for implementing the communication method.SOLUTION: A mobile router 101 communicating with a terminal 81 includes an ACS (Auto Channel Selection) unit 18 for measuring the peripheral frequency congestion, and determining a frequency bandwidth Bw for use in communication based on the measurement results, and a reception unit 101a including multiple reception circuits corresponding to multiple frequency bandwidths, respectively. The ACS unit 18 selects a reception circuit corresponding to the frequency bandwidth Bw for use in communication among multiple reception circuits, and limits power supply to the non-selected reception circuit, while that reception circuit is selected.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mobile router, a mobile router communication method, and a program for realizing the communication method. In particular, the present invention relates to a receiver, a receiving method, and a program thereof.

  A wireless LAN router, which is one form of mobile router, switches the mode from HT (High Throughput) 20 to HT 40, and further to VHT (Very High Throughput) 80, etc., for example, when the communication speed is increased. The speed is increased by increasing the number. On the other hand, in an environment where many carriers (subcarriers) are used for speeding up and the carriers are congested, coexistence with legacy devices and the like is achieved by a function such as 20 MHz / 40 MHz Coexistence. These functions are mainly applied to transmitters and are aimed at preventing interference (reducing interference). For this reason, reduction of the power consumption of a receiver is not considered much.

  For example, when the operation of an access point is started with the Coexistence setting of HT2040 enabled, the operation is degenerated to a 20 MHz bandwidth depending on the wireless congestion around the access point. At this time, the access point receiver operates in the 40 MHz bandwidth even though the terminal transmitter operates in the 20 MHz bandwidth. For this reason, the power consumption of the access point receiver is large. This has a large effect in a mobile router that operates on a battery, and reduction of power consumption is desired.

  As a method for obtaining the wireless congestion status, for example, Patent Document 1 discloses calculating the degree of congestion from the intensity of the received reference signal and the intensity of the received signal. Patent Document 2 discloses that a wireless usage time is obtained for each packet, and a time rate during which the wireless has been used per second is obtained as a wireless congestion degree.

  Further, as a transmission method according to the wireless congestion state, for example, Patent Document 3 discloses changing the transmission encoding rate according to the result of detecting surrounding radio waves. Patent Document 4 discloses that an empty channel found by channel scanning is assigned to its own transmission channel.

International Publication No. 2014/013768 JP 2011-234320 A JP 2009-81753 A JP 2003-249935 A

  As described above, when operating by degenerating to the 20 MHz bandwidth, the receiver of the access point operates in the 40 MHz bandwidth, and the power of the unused portion remains on and power consumption is large. None of Patent Documents 1 to 4 discloses a method for reducing the power consumption of the receiving unit in accordance with wireless congestion.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a mobile router capable of reducing power consumption, a communication method for the mobile router, and a program for realizing the communication method. .

  A mobile router according to the present invention is a mobile router that communicates with a terminal, and measures a congestion state of surrounding frequencies, and determines a frequency bandwidth to be used for the communication based on the measurement result. A channel selection unit, and a receiving unit including a plurality of receiving circuits corresponding to each of a plurality of frequency bandwidths. The ACS unit selects a receiving circuit corresponding to a frequency bandwidth used for the communication from the plurality of receiving circuits, and restricts power supply to an unselected receiving circuit while the receiving circuit is selected. To do.

  A communication method according to the present invention is a communication method of a mobile router that communicates with a terminal, and measures a congestion state of surrounding frequencies and determines a frequency bandwidth to be used for the communication based on the measurement result. A step of selecting a receiving circuit corresponding to a frequency bandwidth used for the communication from a plurality of receiving circuits, and limiting power supply to a non-selected receiving circuit while the receiving circuit is selected. Steps.

  The program according to the present invention is a program for a mobile router that communicates with a terminal, the step of determining a frequency bandwidth to be used for the communication based on a result of measuring the congestion state of surrounding frequencies, and the communication Selecting a receiving circuit corresponding to a frequency bandwidth to be used from among a plurality of receiving circuits; and determining a power supply restriction on a non-selected receiving circuit while the receiving circuit is selected. Let the computer run.

  According to the present invention, it is possible to provide a mobile router capable of reducing power consumption, a mobile router communication method, and a program for realizing the communication method.

1 is a block diagram illustrating a mobile router according to a first embodiment; FIG. 3 is a block diagram illustrating a mobile router according to a second embodiment; It is a schematic graph which illustrates power consumption Pr at the time of reception with respect to frequency bandwidth Bw. It is a block diagram which illustrates the architecture of 64-point FFT by Radix4 (base 4). It is a block diagram which illustrates the architecture of 256 point FFT by Radix4 (base 4). 5 is a flowchart illustrating a communication method according to a second exemplary embodiment; 6 is a diagram illustrating a frequency bandwidth used in Embodiment 2. FIG. 6 is a diagram illustrating a frequency bandwidth used in Embodiment 2. FIG. 6 is a diagram illustrating a frequency bandwidth used in Comparative Example 1 of Embodiment 2. FIG. 6 is a diagram illustrating a frequency bandwidth used in Comparative Example 2 of Embodiment 2. FIG. FIG. 10 is a sequence diagram illustrating communication between a terminal and a mobile router according to the third embodiment. FIG. 10 is a diagram illustrating a frequency bandwidth used in the third embodiment.

[Embodiment 1]
Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram illustrating a mobile router according to the first embodiment.
As shown in FIG. 1, the mobile router 101 includes an antenna 11, a reception unit 101 a, a transmission unit 101 b, and an ACS (Auto Channel Selection) unit 18.

  The mobile router 101 communicates with the terminal 81 via the antenna 11, transmits a signal received from the terminal 81 to the communication network, and transmits a signal received from the communication network to the terminal 81. The mobile router 101 is operated by an internal power supply (not shown) and can be carried by the user.

  The receiving unit 101a processes a signal received from the terminal 81. The receiving unit 101a includes a plurality of receiving circuits corresponding to a plurality of frequency bandwidths.

  The transmission unit 101 b executes processing for transmitting a signal to the terminal 81.

  An ACS (Auto Channel Selection) unit 18 measures a congestion state (communication state) of surrounding frequencies, and determines a frequency bandwidth to be used for communication based on the measurement result. The ACS unit 18 selects a receiving circuit corresponding to the frequency bandwidth used for communication from a plurality of receiving circuits, and restricts power supply to the non-selected receiving circuits while the receiving circuit is selected. Preferably, power supply to the unselected receiving circuit is stopped.

  According to the mobile router 101 in the present embodiment, the power supply to the non-selected receiving circuit is restricted, so that the power consumption of the mobile router can be reduced.

[Embodiment 2]
FIG. 2 is a block diagram illustrating a mobile router according to the second embodiment.

  In the second embodiment, a case where an OFDM (Orthogonal Frequency Division Multiplexing) signal is received will be described. However, there is no limitation in the case of OFDM. The multiplexing scheme may be, for example, FDM (Frequency Division Multiplexing), TDM (Time Division Multiplexing), or CDM (Code Division Multiplexing).

  As shown in FIG. 2, the receiving unit 101a of the mobile router 101 includes a gain adjusting unit 12, an orthogonal detecting unit 13, an AD converting unit 14, a frequency adjusting unit 15, a GI (Guard Interval) removing unit 16, and an FFT (Fast Fourier Transform). ) Unit 17, equalization unit 19, demodulation unit 20, error correction unit 21, and decoding unit 22. The terminal 81 includes a receiving unit 81a, a transmitting unit 81b, a control unit 81c, and a storage unit 81d.

  The gain adjusting unit 12 amplifies the signal transmitted from the terminal 81 and received by the antenna 11 to make it a constant size. At this time, the gain adjustment unit 12 amplifies the gain (gain) to be increased when the received signal power is low, and amplifies the gain to be decreased when the received signal power is high. Thereby, the power of the signal at the output of the gain adjusting unit 12 is made substantially constant.

  The quadrature detection unit 13 performs quadrature detection (orthogonal demodulation) on the signal transmitted from the gain adjustment unit 12. The quadrature-detected signal is divided into an in-phase component signal and a quadrature component signal.

  The signal subjected to quadrature detection by the quadrature detection unit 13 is an analog signal. The AD converter 14 converts this analog signal into a digital signal by AD (Analog Digital) conversion.

  When the terminal 81 or the mobile router 101 moves, a frequency shift may occur on the receiving side that receives the carrier frequency transmitted by the terminal 81 or the mobile router 101 due to the Doppler effect due to the movement. The frequency adjustment unit 15 performs adjustment so as to reduce the frequency shift.

  In the transmission signal transmitted from the terminal 81, a guard interval GI is inserted in front of the data. This is to prevent the data from interfering with multipath delayed wave data that is temporally forward and backward. The GI removal unit 16 removes the guard interval GI from the signal from the frequency adjustment unit 15.

  Here, assuming a situation in which a plurality of mobile routers are installed, in an environment where each mobile router communicates with a terminal, a plurality of frequencies are used, so that a usable frequency bandwidth is limited. Therefore, the ACS unit 18 measures (examines) the usage status (congestion status) of the frequencies around the mobile router 101. As a result of the measurement, a first frequency bandwidth Bw1 having a received power smaller than a predetermined threshold power is obtained.

  It can be seen that the first frequency bandwidth Bw1 is a free frequency bandwidth that is not used by another mobile router. Therefore, the first frequency bandwidth Bw1 is determined as a usable frequency bandwidth, and is determined as the frequency bandwidth Bw used for communication with the terminal 81. The frequency bandwidth Bw is transmitted from the ACS unit 18 to the switch 17sw of the FFT unit 17.

  Thus, the frequency bandwidth Bw is determined according to the communication congestion status. For example, when communication is congested, the frequency bandwidth Bw is determined to be 20 MHz, and when communication is not congested, the frequency bandwidth Bw is determined to be 80 MHz.

  In the second embodiment, an example is shown in which ACS is used as a selection method (determination method) of usable frequency bandwidth Bw (frequency channel). This is not a limitation. The method of selecting the frequency bandwidth Bw may be realized by various prior arts other than ACS.

  The receiving unit 101a includes a plurality of receiving circuits corresponding to each of a plurality of frequency bandwidths. Each receiving circuit corresponding to a plurality of frequency bandwidths includes, for example, each of a plurality of FFT circuits. The FFT unit 17 includes a plurality of FFT circuits and a switch 17sw corresponding to each of the plurality of frequency bandwidths. The plurality of FFT circuits include, for example, a 64-point FFT circuit 17a, a 256-point FFT circuit 17b, and a 1024-point FFT circuit 17c.

  The ACS unit 18 operates the switch 17sw of the FFT unit 17 to select a first FFT circuit 17fc that performs FFT (fast Fourier transform) processing with the number of FFT points corresponding to the frequency bandwidth Bw from among the plurality of FFT circuits. . The ACS unit 18 limits the power supply of the FFT circuits other than the first FFT circuit 17fc to reduce the power consumption while the first FFT circuit 17fc is selected. Preferably, power supply to the FFT circuits other than the first FFT circuit 17fc is stopped.

  Note that the number of FFT circuits to be selected depends on the frequency bandwidth Bw, and may be one or more. The FFT process is performed on the signal transmitted from the GI removal unit 16 to the FFT unit 17.

  Here, a specific example will be described for performing FFT processing with the number of FFT points corresponding to the frequency bandwidth Bw.

  For example, when the frequency bandwidth Bw is 20 MHz, the corresponding number of FFT points is 64, and the 64-point FFT circuit 17a is selected as the first FFT circuit 17fc, and the FFT processing is performed. While the 64-point FFT circuit 17a is selected, the power supply is turned on to operate only in the portion corresponding to the frequency bandwidth Bw to be used (in this example, the 64-point FFT circuit 17a). That is, the power supply of the FFT circuits other than the 64-point FFT circuit 17a is limited.

  When the frequency bandwidth Bw is 40 MHz, for example, the corresponding number of FFT points is 256 points, and the 256-point FFT circuit 17b is selected as the first FFT circuit 17fc, and the FFT process is performed. For example, when the frequency bandwidth Bw is 80 MHz, the corresponding number of FFT points is 1024 points, and the 1024-point FFT circuit 17c is selected as the first FFT circuit 17fc to perform the FFT processing.

  As described above, the mobile router 101 has the function of determining the first frequency bandwidth Bw1 having the received power smaller than the predetermined threshold power as the frequency bandwidth Bw, and the non-selection corresponding to the frequency bandwidth Bw. A function of limiting power supply of the FFT circuit. That is, the mobile router 101 has a function of limiting the receiving circuit (FFT unit 17) according to the communication congestion status.

  The frequency bandwidth Bw is not limited to 20, 40, and 80 MHz. Other frequency bandwidths may be used. Further, the corresponding number of FFT points may be a number other than 64, 256, or 1024, and the FFT unit 17 may include an FFT circuit that performs processing with an FFT point other than 64, 256, or 1024.

  In the communication path between the terminal 81 and the mobile router 101, the signal undergoes phase fluctuation or amplitude fluctuation due to reflection or the like. These fluctuations are called communication path transfer functions. That is, the received signal is the transmission signal multiplied by the transfer function of the communication path. The equalization unit 19 multiplies the received signal by the reciprocal of the transfer function of the communication path, thereby removing phase fluctuations and amplitude fluctuations due to reflection in the communication path. An example of the equalization method is zero forcing.

  The demodulator 20 decodes the signal transmitted from the equalizer 19 to the demodulator 20. That is, the demodulator 20 converts symbol data (signal) including the in-phase component I and the quadrature component Q into one signal series. The symbol data is demapped and converted into a signal of one signal series.

  The error correction unit 21 performs error correction processing on the signal transmitted from the demodulation unit 20 to the error correction unit 21. Thereby, the error rate of the signal transmitted to the error correction unit 21 is reduced and the reliability of the signal is improved.

  The decoding unit 22 decodes the signal encoded in the terminal 81. In the terminal 81, for example, a Viterbi decoding method is used to decode the convolutionally encoded signal.

FIG. 3 is a schematic graph illustrating power consumption during reception with respect to the frequency bandwidth Bw.
In FIG. 3, the vertical axis represents the power consumption Pr (W) at the time of reception, and the horizontal axis represents the frequency bandwidth Bw (MHz).

  As shown in FIG. 3, the power consumption when the frequency bandwidth Bw is 20 MHz is smaller than the power consumption when the frequency bandwidth Bw is 80 MHz. That is, when the frequency bandwidth Bw is reduced, the power consumption Pr during reception is reduced.

FIG. 4 is a block diagram illustrating the architecture of a 64-point FFT using Radix4 (base 4).
FIG. 5 is a block diagram illustrating the architecture of a 256 point FFT with Radix4 (base 4).

  As shown in FIGS. 4 and 5, the 64-point FFT circuit and the 256-point FFT circuit include a plurality of memories and a plurality of Radix4 butterfly computation processes. Since the FFT circuit includes these memories and arithmetic processing, power consumption increases. The power consumption of the FFT circuit is large in the power consumption of the entire receiver.

  The number of memories included in the 256-point FFT circuit is larger than the number of memories included in the 64-point FFT circuit. The same applies to the butterfly calculation process. That is, as the number of FFT points increases, the power consumption increases. Therefore, it is desirable to turn on the power supply of only the minimum necessary FFT circuit and limit the power supply of other FFT circuits, for example, to turn off the power supply.

  On the other hand, the number of FFT points required for reception varies depending on the number of subcarriers. As the number of subcarriers increases, the number of FFT points required increases. Further, the required frequency bandwidth Bw varies depending on the number of subcarriers. As the number of subcarriers increases, the frequency bandwidth Bw increases.

  Therefore, it is desirable that the mobile router 101 be operated only in the FFT circuit corresponding to the frequency bandwidth Bw used for communication. That is, the power supply of only the FFT circuit corresponding to the frequency bandwidth Bw is turned on, and the power supply of other FFT circuits is limited.

  In the second embodiment, as described above, the FFT unit 17 selects the first FFT circuit 17fc that performs the FFT processing with the number of FFT points corresponding to the frequency bandwidth Bw from among the plurality of FFT circuits, and is not selected. The power supply of the FFT circuit is limited. As a result, the power supply of the parts that are not required is restricted, and thus the power consumption of the mobile router can be reduced.

Next, a communication method according to the second embodiment will be described.
FIG. 6 is a flowchart illustrating a communication method according to the second embodiment.

  As shown in FIG. 6, the ACS unit 18 of the mobile router 101 measures the usage status (congestion status) of frequencies around the mobile router 101 (step S <b> 101).

  Next, the ACS unit 18 determines the frequency bandwidth Bw used for communication with the terminal 81 based on the measurement result. For example, the ACS unit 18 searches for the first frequency bandwidth Bw1 having a reception power smaller than a predetermined threshold power (step S102). The received power smaller than the threshold power is considered as a frequency bandwidth that is not currently used by other mobile routers.

  Next, the ACS unit 18 determines the first frequency bandwidth Bw1 as the frequency bandwidth Bw used for communication with the terminal 81 (step S103).

  Next, when the frequency bandwidth Bw is 20 MHz (megahertz), the ACS unit 18 selects the 64-point FFT circuit 17a (step S104).

  Next, when the frequency bandwidth Bw is 20 MHz, the ACS unit 18 switches the switch 17sw so that the GI removal unit 16 and the 64-point FFT circuit 17a are connected (step S105).

  Next, while the 64-point FFT circuit 17a is selected, the ACS unit 18 restricts power supply to the FFT circuits other than the 64-point FFT circuit 17a, and turns off the power, for example. That is, only the power source of the 64-point FFT circuit 17a in the FFT circuit is turned on (step S106).

  Further, the ACS unit 18 selects the 256-point FFT circuit 17b when the frequency bandwidth Bw is 40 MHz instead of 20 MHz (step S107).

  Next, when the frequency bandwidth Bw is 40 MHz instead of 20 MHz, the ACS unit 18 switches the switch 17sw so that the GI removal unit 16 and the 256-point FFT circuit 17b are connected (step S108).

  Next, while the 256-point FFT circuit 17b is selected, the ACS unit 18 restricts power supply to the FFT circuits other than the 256-point FFT circuit 17b, and turns off the power, for example. That is, only the power supply of the 256-point FFT circuit 17b in the FFT circuit is turned on (step S109).

  Next, the ACS unit 18 selects the 1024-point FFT circuit 17c when the frequency bandwidth Bw is 80 MHz instead of 40 MHz instead of 20 MHz (step S110).

  Further, when the frequency bandwidth Bw is not 40 MHz but 80 MHz instead of 20 MHz, the ACS unit 18 switches the switch 17sw so that the GI removal unit 16 and the 1024-point FFT circuit 17c are connected (step S111).

  Next, while the 1024 point FFT circuit 17c is selected, the ACS unit 18 restricts power supply to the FFT circuits other than the 1024 point FFT circuit 17c, and turns off the power, for example. That is, only the power source of the 1024 point FFT circuit 17c is turned on in the FFT circuit (step S112).

  Next, the ACS part 18 returns to step S101, when the acquired frequency bandwidth Bw is not 20 MHz but 40 MHz, and is not 80 MHz.

  By these steps S101 to S112, it is possible to provide a notification device and a communication method capable of reducing power consumption. Note that some or all of the above steps S101 to S112 may be realized by a CPU (Central Processing Unit) (not shown) of the mobile router 101 executing a program (notification control program). That is, steps S101 to S112 may be programs that are executed by a computer. Steps S101 to S112 may be realized by any combination of hardware, firmware, and software.

  Further, the ACS unit 18 uses a frequency bandwidth allocation information (channel) that is not allocated based on frequency bandwidth allocation information notified from a mobile router different from the mobile router 101 via the network or via the terminal 81. May be determined as the frequency bandwidth Bw used for communication.

  Further, the ACS unit 18 has been described with reference to the example in which the frequency usage state is measured using the output signal of the gain adjusting unit 12. This is not a limitation. For example, the usage status of the frequency may be measured from the output signal of the quadrature detection unit 13.

FIG. 7 is a diagram illustrating a frequency bandwidth used in the second embodiment.
FIG. 8 is a diagram illustrating a frequency bandwidth used in the second embodiment.

  FIG. 7 shows an example of channel assignment when the second embodiment is applied to a 2.4 GHz band channel of IEEE 802.11n, which is one of the wireless LAN standards. In the 2.4 GHz band, there are 1 to 13 channels.

  As a result of the ACS unit 18 measuring the usage situation of the frequencies around the mobile router 101 and searching for a frequency band having a received power smaller than a predetermined threshold power, the channel 1ch is found. Therefore, as shown in FIG. 7, channel 1ch is determined as a frequency band used for communication with terminal 81.

  Thereby, the service can be started in advance using the channel 1ch having the 20 MHz bandwidth. As a result, the current of the reception circuit (FFT circuit) of the mobile router 101 can be reduced (reduced).

  FIG. 8 is an example in the case of the W52 band of IEEE802.11n. Even in this case, according to the second embodiment, the operation can be started with the 20 MHz bandwidth as in the case of the 2.4 GHz band described above. Thereby, the power saving of the receiving circuit of the mobile router 101 can be achieved.

  If the second embodiment is not applied in the W52 band, another channel (mobile router different from mobile router 101) used by another station (mobile router 101) is used as an extension channel having an 80 MHz width used by the own station (mobile router 101). May suffer. As a result, interference may occur and throughput may decrease due to retransmission or the like.

  In general, it is necessary to switch the FFT circuit in units of nanoseconds, for example. However, for example, it is difficult to dynamically switch between a 64-point FFT circuit and a 256-point FFT circuit in nanosecond units. For this reason, when switching from the 256-point FFT circuit to the 64-point FFT circuit, for example, the operation of the wireless service (access point) is once stopped and the switching is performed by changing the value of the FFT circuit setting register in the access point.

  Therefore, in the second embodiment, when the access point (mobile router 101) starts operation, the available frequency bandwidth (frequency channel) is detected, and the state is previously degenerated (optimized FFT circuit to be used). Operation). For example, when the frequency bandwidth Bw is 20 MHz, the 64-point FFT circuit 17a can be set and the operation can be started in a degenerated state. Therefore, as described above, it is not necessary to once stop the operation of the access point.

As described above, when a degenerate operation is predicted, an operation of the mobile router can be started by operating an FFT circuit having a smaller number of FFT points in advance. As a result, the power supply of the parts that are not required is restricted, and thus the power consumption of the mobile router can be reduced. As a result, a mobile router capable of reducing power consumption and a communication method thereof can be provided.
[Comparative Example 1 of Embodiment 2]
FIG. 9 is a diagram illustrating frequency bandwidths used in comparative example 1 of the second embodiment.
FIG. 9 shows the frequency bandwidth transmitted by the terminal (upper stage) and the frequency bandwidth received by the mobile router (lower stage) in IEEE 802.11ac.

  In IEEE802.11ac, the frequency bandwidth to be used increases from VHT80 to VHT160. The transmission side can perform communication without interference according to the specification of Dynamic Operation of the frequency bandwidth to be used (used channel width).

  On the other hand, on the receiving side, even in an environment where the frequency is congested, standby is performed with the maximum FFT circuit initially set enabled, and power consumption remains large. In IEEE 802.11ac, for example, as shown in FIG. 9, it is necessary to stand by with an 80 MHz bandwidth, and power consumption is large.

[Comparative Example 2 of Embodiment 2]
FIG. 10 is a diagram illustrating a frequency bandwidth used in Comparative Example 2 of the second embodiment.
FIG. 10 illustrates the frequency bandwidth in the case of HT2040 setting. The frequency bandwidth transmitted by the terminal (upper stage) and the frequency bandwidth received by the mobile router (lower stage) are shown.

  As shown in FIG. 10, the transmission frequency bandwidth of the terminal is, for example, 20 MHz. On the other hand, since the mobile router needs to perform standby by enabling the maximum FFT circuit, the reception frequency bandwidth is 40 MHz, and the power consumption is large.

[Embodiment 3]
Next, Embodiment 3 will be described.
FIG. 11 is a sequence diagram illustrating communication between a terminal and a mobile router according to the third embodiment.

  As illustrated in FIG. 11, for example, the ACS unit 18 of the mobile router 101 transmits a terminal capability information request to the transmission unit 101 b with power-on as a trigger. Next, the transmission unit 101b broadcasts (transmits) the terminal capability information request toward the terminal 81. The terminal capability information request is a signal that can be received by all terminals connected to the mobile router.

  Next, the receiving unit 81a of the terminal 81 receives the terminal capability information request. Next, the receiving unit 81a transmits a terminal capability information request to the control unit 81c. Next, the control unit 81c instructs the transmission unit 81b to read the terminal capability information from the storage unit 81d. Next, the transmission unit 81b performs a read operation, and reads terminal capability information from the storage unit 81d. Next, the transmission unit 81 b transmits the read terminal capability information to the mobile router 101.

  Next, the receiving unit 101a receives terminal capability information. Next, the receiving unit 101 a transmits terminal capability information to the ACS unit 18. In this way, the ACS unit 18 of the mobile router 101 acquires the terminal capability information of the terminal 81.

  The acquired terminal capability information includes, for example, a second frequency bandwidth Bw2 that is a frequency bandwidth with which the terminal 81 can communicate.

  Therefore, the ACS unit 18 determines the frequency bandwidth Bw used for communication between the terminal 81 and the mobile router 101 based on the terminal capability information. For example, when the second frequency bandwidth Bw2 in the terminal capability information is 40 MHz, the ACS unit 18 determines the frequency bandwidth Bw as 40 MHz.

FIG. 12 is a diagram illustrating a frequency bandwidth used in the third embodiment.
FIG. 12 also shows the terminal 81, the mobile router 101, and the like.

  As shown in FIG. 12, the terminal 81 notifies the mobile router 101 of the second frequency bandwidth Bw2, which is the frequency bandwidth with which the terminal 81 can communicate, included in the terminal capability information. In this example, 20 MHz, for example, is notified from the terminal 81 to the mobile router 101 as the second frequency bandwidth Bw2. As a result, the mobile router 101 can start operation by limiting the reception circuit to 20 MHz that is the same as the frequency bandwidth of the terminal 81. Note that the frequency bandwidth (second frequency bandwidth Bw2) in which the terminal 81 can communicate is determined by, for example, an IFFT (Inverse FFT) circuit included in the terminal 81.

  Thus, in Embodiment 3, since the receiving circuit is limited in consideration of the frequency bandwidth with which the terminal can communicate, the power consumption of the mobile router can be further reduced.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 11 ... Antenna 12 ... Gain adjustment part 13 ... Quadrature detection part 14 ... AD conversion part 15 ... Frequency adjustment part 16 ... GI removal part 17 ... FFT part 17a ... 64-point FFT circuit 17b ... 256-point FFT circuit 17c ... 1024-point FFT circuit DESCRIPTION OF SYMBOLS 17fc ... 1st FFT circuit 17sw ... Switch 18 ... ACS part 19 ... Equalization part 20 ... Demodulation part 21 ... Error correction part 22 ... Decoding part 81 ... Terminal 101 ... Mobile router Bw ... Frequency bandwidth Bw1 ... 1st frequency bandwidth Bw2 ... Second frequency bandwidth Pr ... Power consumption I ... In-phase component Q ... Quadrature component

Claims (9)

A mobile router that communicates with a terminal,
An ACS (Auto Channel Selection) unit that measures a congestion state of surrounding frequencies and determines a frequency bandwidth to be used for the communication based on the measurement result;
A receiving unit including a plurality of receiving circuits corresponding to each of a plurality of frequency bandwidths;
With
The ACS unit selects a receiving circuit corresponding to a frequency bandwidth used for the communication from the plurality of receiving circuits, and restricts power supply to an unselected receiving circuit while the receiving circuit is selected. Mobile router. A mobile router that communicates with a terminal,
An ACS unit that acquires terminal capability information including a frequency bandwidth in which the terminal can communicate from the terminal, and determines a frequency bandwidth to be used for the communication based on the terminal capability information;
A receiving unit including a plurality of receiving circuits corresponding to each of a plurality of frequency bandwidths;
With
The ACS unit selects a receiving circuit corresponding to a frequency bandwidth with which the terminal can communicate from the plurality of receiving circuits, and supplies power to an unselected receiving circuit while the receiving circuit is selected. Limit the mobile router. Each of the plurality of receiving circuits includes each of a plurality of FFT (Fast Fourier Transform) circuits,
The ACS unit selects an FFT circuit that performs an FFT process with the number of FFT points corresponding to a frequency bandwidth used for the communication from the plurality of FFT circuits, and is not selected while the FFT circuit is selected. The mobile router according to claim 1, wherein power supply to the FFT circuit is limited. A mobile router communication method for communicating with a terminal,
Measuring a congestion situation of surrounding frequencies, and determining a frequency bandwidth to be used for the communication based on the measurement result;
Selecting a receiving circuit corresponding to a frequency bandwidth used for the communication from a plurality of receiving circuits;
Limiting power supply to unselected receiver circuits while the receiver circuit is selected;
Mobile router communication method equipped with. A mobile router communication method for communicating with a terminal,
Obtaining terminal capability information including a frequency bandwidth with which the terminal can communicate from the terminal, and determining a frequency bandwidth to be used for the communication based on the terminal capability information;
Selecting a receiving circuit corresponding to a frequency bandwidth used for the communication from a plurality of receiving circuits;
Limiting power supply to unselected receiver circuits while the receiver circuit is selected;
Mobile router communication method equipped with. Each of the plurality of receiving circuits includes each of a plurality of FFT (Fast Fourier Transform) circuits,
Selecting an FFT circuit that performs FFT processing with the number of FFT points corresponding to the frequency bandwidth used for the communication from the plurality of FFT circuits;
Limiting power supply to unselected FFT circuits while the FFT circuit is selected;
The mobile router communication method according to claim 4 or 5, further comprising: A mobile router program that communicates with a terminal,
Determining a frequency bandwidth to be used for the communication based on a result of measuring a congestion state of surrounding frequencies;
Selecting a receiving circuit corresponding to a frequency bandwidth used for the communication from a plurality of receiving circuits;
Determining a power supply limit for a non-selected receiver circuit while the receiver circuit is selected;
A mobile router program that runs a computer. A mobile router program that communicates with a terminal,
Determining a frequency bandwidth to be used for the communication based on terminal capability information including a communicable frequency bandwidth of the terminal acquired from the terminal;
Selecting a receiving circuit corresponding to a frequency bandwidth used for the communication from a plurality of receiving circuits;
Determining a power supply limit for a non-selected receiver circuit while the receiver circuit is selected;
A mobile router program that runs a computer. Each of the plurality of receiving circuits includes each of a plurality of FFT (Fast Fourier Transform) circuits,
Selecting an FFT circuit that performs FFT processing with the number of FFT points corresponding to the frequency bandwidth used for the communication from the plurality of FFT circuits;
Determining a power supply limit for a non-selected FFT circuit while the FFT circuit is selected;
The mobile router program according to claim 7 or 8, further comprising:

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