JP2008172304A - Radio communication system, base station, and terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system that can lighten a processing load at a transmission side, can be miniaturized, and can reduce power consumption, and to provide a base station and a terminal. <P>SOLUTION: The radio communication system 10 contains the base station 100 and first to N-th (N is an integer of not less than 2) terminals 200<SB>1</SB>-200<SB>N</SB>. The first to N-th terminals 200<SB>1</SB>-200<SB>N</SB>transmit signals, where carrier frequencies orthogonally cross each other, to the base station simultaneously. The base station 100 receives the signal from the first to N-th terminals 200<SB>1</SB>-200<SB>N</SB>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication system, a base station, and a terminal.

  Conventionally, a digital modulation / demodulation technique has attracted attention as a technique for increasing the amount of information transmitted in wireless communication. Wireless communication is suitable for a one-to-many communication system, and this digital modulation / demodulation technique is essential in digital television broadcasting or the like in which data, audio signals, and image signals are transmitted. As one of such digital modulation / demodulation technologies, ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) uses an Orthogonal Frequency Division Multiplexing (hereinafter OFDM) technology.

  In the OFDM technology, a transmission apparatus maps a bit string of transmission data with a symbol mapper, and then performs processing such as Inverse Fast Fourier Transform (IFFT) to perform multicarrier transmission. Since the subcarrier has a multi-bit information amount by the modulation technique, the information amount transmitted by the OFDM technique can be greatly increased.

Such OFDM technology is also applied to multi-user communication systems. For example, Non-Patent Document 1 discloses OFDM-FDMA (Frequency Division Multiplexing Access) technology that assigns subcarriers to each user so that transmission power is minimized according to the transmission rate requested by each user. Patent Document 1 discloses an OFDM-FDMA technique that identifies an application of each user and assigns subcarriers so as to satisfy communication quality for each application.
JP 2003-18117 A Cheong Yui Wong et al., “Multiuser OFDM with adaptive Subcarrier, Bit and Power Allocation”, IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL.17, NO.10, OCTOBER 1999

  However, in the technologies disclosed in Non-Patent Document 1 and Patent Document 1, many-to-many wireless communication is performed between multi-users, but wireless communication between one transmission device and one reception device is performed. Assumed. Therefore, the transmission apparatus performs IFFT processing on the data from each user and transmits the data, and the reception apparatus extracts the received signal by FFT processing. That is, there is a problem in that it is necessary to perform IFFT processing on the transmission side, and it is not possible to reduce the processing load of the transmission device, to reduce the size, and to reduce power consumption.

  The present invention has been made in view of the technical problems as described above, and an object of the present invention is to provide a radio communication system and a base capable of reducing the processing load on the transmission side, reducing the size, and reducing the power consumption. It is to provide a station and a terminal.

In order to solve the above problems, the present invention
A base station,
First to Nth terminals (N is an integer of 2 or more),
The first to N-th terminals are
Simultaneously transmit signals with carrier frequencies orthogonal to each other to the base station,
The base station is
The present invention relates to a wireless communication system that simultaneously performs reception processing on signals from the first to Nth terminals.

In the wireless communication system according to the present invention,
The first to N-th terminals are
The signal after the first modulation processing is transmitted to the base station all at once,
The base station is
A first demodulation process corresponding to the first modulation process can be performed on a signal obtained by performing a predetermined demodulation process on the signals from the first to Nth terminals.

In the wireless communication system according to the present invention,
The base station is
Transmitting a start signal to the first to Nth terminals;
The first to N-th terminals are
Signals having carrier frequencies orthogonal to each other can be transmitted to the base station simultaneously in synchronization with the start signal.

  According to any one of the above inventions, since the first to Nth terminals transmit at carrier frequencies orthogonal to each other, each terminal does not need to perform IFFT processing, and the terminal configuration is greatly simplified. Power consumption can be reduced. In addition, the base station can receive data from a plurality of terminals at a time in a short time. Therefore, communication management of a plurality of terminals can be simplified in the base station.

In the wireless communication system according to the present invention,
The base station is
Prior to transmission of the start signal, a wakeup signal is transmitted to the first to Nth terminals,
The first to N-th terminals are
When in the sleep state, the wake-up signal is received to shift to the sleep-out state, and the signal can be transmitted to the base station in the sleep-out state.

In the wireless communication system according to the present invention,
The base station is
Prior to transmission of the start signal, a wakeup signal is transmitted to the first to Nth terminals,
The first to N-th terminals are
An electromotive force is generated based on the wakeup signal, and signals with carrier frequencies orthogonal to each other can be transmitted to the base station by the electromotive force.

  According to any one of the above inventions, it is possible to further reduce the power consumption of each of the first to Nth terminals.

In the wireless communication system according to the present invention,
When the reference frequency is fc,
The j-th terminal (1 ≦ j ≦ N, j is an integer) is
A signal having a carrier frequency of j × fc can be transmitted to the base station.

  According to the present invention, the first to Nth terminals can transmit with signals having carrier frequencies orthogonal to each other with a simple configuration.

In the wireless communication system according to the present invention,
Each of the first to Nth terminals is
The signal after phase modulation can be transmitted to the base station.

  In the present invention, the distance from the base station to each terminal is often not uniform, and amplitude control is not required compared to the case where the signal from each terminal is amplitude-modulated, and the configuration of each terminal can be simplified.

In the wireless communication system according to the present invention,
Each of the first to Nth terminals is
Transmitting the generated signal to the base station without performing inverse fast Fourier transform on the signal to be transmitted;
The base station is
A received signal can be generated from the signals from the first to Nth terminals by fast Fourier transform processing.

In the wireless communication system according to the present invention,
Signals transmitted by the first to Nth terminals may form an Orthogonal Frequency Division Multiplexing (OFDM) signal.

  According to any one of the above-described inventions, each terminal does not need to perform IFFT processing, the configuration of the terminal can be greatly simplified, and power consumption can be reduced. In addition, the base station can receive data from a plurality of terminals at a time by FFT processing or the like by a known OFDM signal reception process. Therefore, communication management of a plurality of terminals can be simplified in the base station.

The present invention also provides
A base station for receiving signals from first to N-th (N is an integer of 2 or more) terminals,
A receiving unit that receives signals transmitted simultaneously to the base station by the first to Nth terminals, the carrier frequency of each terminal being orthogonal to each other;
The present invention relates to a base station including a reception processing unit that performs reception processing on signals from the first to Nth terminals.

In the base station according to the present invention,
The first to Nth terminals transmit signals after the first modulation process all at once,
A first demodulation process corresponding to the first modulation process can be performed on a signal obtained by performing a predetermined demodulation process on the signals from the first to Nth terminals.

In the base station according to the present invention,
Transmitting a start signal to the first to Nth terminals;
The first to Nth terminals can receive a signal in which signals having carrier frequencies orthogonal to each other are transmitted simultaneously in synchronization with the start signal.

In the base station according to the present invention,
Prior to transmission of the start signal, a wakeup signal is transmitted to the first to Nth terminals,
The first to Nth terminals in the sleep state can be shifted to a sleep out state in which a signal is transmitted to the base station by the wakeup signal.

In the base station according to the present invention,
Prior to transmission of the start signal, a wakeup signal is transmitted to the first to Nth terminals,
The first to Nth terminals can generate an electromotive force based on the wake-up signal, and the electromotive force can cause the base station to transmit signals having carrier frequencies orthogonal to each other.

In the base station according to the present invention,
When the reference frequency is fc,
It is possible to receive a signal whose carrier frequency of the j-th terminal (1 ≦ j ≦ N, j is an integer) is j × fc.

In the base station according to the present invention,
From each of the first to Nth terminals, a signal generated without performing an inverse fast Fourier transform process on a signal to be transmitted is received, and a received signal is obtained by performing a fast Fourier transform process on the signal. Can be generated.

In the base station according to the present invention,
An Orthogonal Frequency Division Multiplexing (OFDM) signal may be formed by signals transmitted by the first to Nth terminals.

  According to any one of the above-described inventions, it is possible to provide a base station constituting a wireless communication system capable of reducing the processing load on the transmission side, reducing the size, and reducing the power consumption.

The present invention also provides
A terminal of a wireless communication system including a base station and first to Nth (N is an integer of 2 or more) terminals,
A receiving unit for receiving a start signal from the base station;
The present invention relates to a terminal including a transmission unit that transmits a signal in which carrier frequencies of the terminals of the first to Nth terminals are orthogonal to each other to the base station in synchronization with the start signal.

In the terminal according to the present invention,
The transmitter is
Transmitting the first modulated signal to the base station;
The base station is
A first demodulation process corresponding to the first modulation process can be performed on a signal obtained by performing a predetermined demodulation process on the signals from the first to Nth terminals.

In the terminal according to the present invention,
Prior to transmission of the start signal, a wake-up signal is received from the base station,
By receiving the wake-up signal in the sleep state, it is possible to shift to a sleep-out state in which a signal is transmitted to the base station.

In the terminal according to the present invention,
Prior to transmission of the start signal, a wake-up signal is received from the base station,
An electromotive force is generated based on the wake-up signal, and a signal can be transmitted to the base station by the electromotive force.

In the terminal according to the present invention,
When the reference frequency is fc,
The transmitter is
A signal having a carrier frequency j (1 ≦ j ≦ N, j is an integer) × fc associated with the terminal can be transmitted.

In the terminal according to the present invention,
The transmitter is
The signal after phase modulation can be transmitted to the base station.

In the terminal according to the present invention,
Transmitting the generated signal to the base station without performing inverse fast Fourier transform on the signal to be transmitted;
The base station is
A received signal can be generated from the signals from the first to Nth terminals by fast Fourier transform processing.

In the terminal according to the present invention,
Signals transmitted by the first to Nth terminals may form an Orthogonal Frequency Division Multiplexing (OFDM) signal.

  According to any one of the above-described inventions, it is possible to provide a terminal constituting a wireless communication system capable of reducing the processing load on the transmission side, reducing the size, and reducing the power consumption.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

1. Wireless Communication System FIG. 1 shows an outline of the configuration of a wireless communication system according to this embodiment.

The wireless communication system 10 of the present embodiment includes a base station 100 and first to N-th (N is an integer of 2 or more) terminals 200 ₁ to 200 _N. The base station 100 may send a signal to the terminal ₂₀₀ 1 to 200 DEG _N of the first to N via a radio transmission path, the terminal ₂₀₀ 1 to 200 DEG _N of the first to N via a wireless transmission path The signal from can be received. The _first to _N-th terminals 200 ₁ to 200 _N have substantially the same configuration, but can simultaneously transmit signals having carrier frequencies orthogonal to each other to the base station 100. Each terminal transmits a signal having a carrier frequency associated with the terminal to base station 100. For example, when the reference frequency is fc hertz, the j-th (1 ≦ j ≦ N, j is an integer) terminal 200 _j can transmit a signal having a carrier frequency of j × fc hertz to the base station 100. Accordingly, the _first to _N-th terminals 200 ₁ to 200 _N can transmit signals having carrier frequencies orthogonal to each other to the base station 100 with a simple configuration.

In the wireless communication system 10 according to the present embodiment, the _first to _Nth terminals 200 ₁ to 200 _N have sensors, and a sensor network in which the base station 100 collects sensing information acquired for each terminal can be formed. ing. It is desirable that each terminal is light and small and can operate with low power consumption, and the configuration of each terminal needs to be simplified.

  2 (A), 2 (B), and 2 (C) are operation explanatory diagrams of the wireless communication system 10 of the present embodiment.

In the wireless communication system 10 in the present embodiment, first, it is assumed that the _first to _Nth terminals 200 ₁ to 200 _N have transitioned from a sleep-out state, which is a normal operation state, to a sleep state. Here, the sleep state is a state in which the frequency of the operation clock of the terminal is lower than the frequency of the operation clock of the terminal in the sleep-out state and operates with low power consumption. Alternatively, in the sleep state, only some of the circuit blocks may be supplied with operation clocks, and the operation clocks of other circuit blocks may be stopped. In any case, the power consumption of the terminal can be reduced in the sleep state.

Therefore, first, the base station 100 transmits a wake-up signal to the _first to _N-th terminals 200 ₁ to 200 _N as shown in FIG. The terminal ₂₀₀ 1 to 200 DEG _N first to N which has received the wake-up signal is changed to the sleep-out state. In the sleep-out state, each terminal can send the already acquired sensing information to the base station 100. The _first to _N-th terminals 200 ₁ to 200 _{N that} have transitioned to the sleep-out state are configured to return to the sleep state again after a predetermined period of time has elapsed after transition to the sleep-out state. In this way, low power consumption of each terminal is realized.

Next, the base station 100 that has transmitted the wake-up signal transmits a start signal to the _first to _Nth terminals 200 ₁ to 200 _N as shown in FIG. This start signal may be the same signal as the wake-up signal. For example, every time a wakeup signal or a start signal is received, the start signal and the wakeup signal can be made the same signal by changing the state that defines the operation of each terminal. The start signal and the wake-up signal may be a pulse signal having a short pulse waveform or a single tone signal.

After that, each terminal that has received the start signal acquires sensing information or transmits already acquired sensing information to the base station 100 as illustrated in FIG. At this time, the _first to _N-th terminals 200 ₁ to 200 _N simultaneously transmit signals whose carrier frequencies are orthogonal to each other. More specifically, the _first to _N-th terminals 200 ₁ to 200 _N simultaneously transmit signals having carrier frequencies orthogonal to each other in synchronization with the start signal from the base station 100. As a result, the base station 100 simultaneously performs reception processing on signals from the _first to _N-th terminals 200 ₁ to 200 _N.

Here, since the received signals from the _first to _N-th terminals 200 ₁ to 200 N received by the base station 100 are transmitted simultaneously, for example, while N types of carrier signals are orthogonal to each other, the base station 100 Signals from the _first to _N-th terminals 200 ₁ to 200 _N are received as OFDM signals.

  FIG. 3 is an explanatory diagram of the OFDM signal in the present embodiment.

As shown in FIG. 3, when the signal level is taken on the vertical axis and the frequency axis is taken on the horizontal axis, the power spectrum of the OFDM signal is the signals S _{1 to} S of the carrier frequencies of the _first to _Nth terminals 200 ₁ to 200 _N. It becomes a spectrum close to a rectangle obtained by synthesizing _N spectra. The signal of each carrier frequency is a signal after primary modulation. The signal of each carrier frequency is desirably a signal after phase modulation such as BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), or 8-phase PSK. This is because the distance from the base station 100 to each terminal is often not uniform, and amplitude control is complicated when the signal from each terminal is a signal after amplitude modulation.

As a result, the _first to _N-th terminals 200 ₁ to 200 _N transmit the signals after the first modulation process all at once. The base station 100 performs a first demodulation process corresponding to the first modulation process on a signal obtained by performing a predetermined demodulation process on the signals from the _first to _N-th terminals 200 ₁ to 200 _N. .

The base station 100 that has received signals from the _first to _Nth terminals 200 ₁ to 200 _N receives an OFDM signal as shown in FIG. That is, each of the _first to _N-th terminals 200 ₁ to 200 _N transmits the generated signal to the base station 100 without performing IFFT processing on the signal to be transmitted. And base station 100 produces | generates a received signal by the FFT process from the signal from the _{1st- Nth} terminal 2001-200N.

2. Base Station and Terminals Hereinafter, the base station 100 and the _first to _Nth terminals 200 ₁ to 200 _{N in} FIG. ₁ will be described. The terminal ₂₀₀ 1 to 200 DEG _N first to N, since the carrier frequency has substantially the same configuration each terminal except different point will be described first terminal 200 ₁ for.

2.1 Configuration Example FIG. 4 shows the base station 100 in the present embodiment and the outline of the first terminal 200 ₁ configuration.

Base station 100 includes a power feeding circuit 110, a transmission circuit 130, and a reception circuit 150. The power feeding circuit 110 transmits a wake-up signal via a radio wave or a magnetic field, and performs control to generate power for the _first to _N-th terminals 200 ₁ to 200 _N. The transmission circuit 130 performs control to transmit a start signal from the base station 100 to the _first to _N-th terminals 200 ₁ to 200 _N. The reception circuit 150 performs control to receive signals from the _first to _N-th terminals 200 ₁ to 200 _N as OFDM signals.

The first terminal 200 ₁ includes a power receiving circuit 210 ₁ , a receiving circuit 230 ₁ , and a transmitting circuit 250 ₁ . Incoming circuit 210 _1, based on the control from the power supply circuit 110 performs control to generate power to operate the first circuit terminal 200 _1. Receiving circuit 230 ₁ performs control for receiving a signal from the transmitter 130 of base station 100. The transmission circuit 250 ₁ performs control to transmit a response signal synchronized with the start signal received by the reception circuit 230 ₁ to the base station 100. In the present embodiment, the first terminal 200 ₁ is in the sleep state in which a battery-transitions to the sleep-out state by the wake-up signal from the power supply circuit 110, the power of the battery is first of each circuit of the terminal 200 ₁ To be supplied. The transmission circuit 250 ₁ performs control to send sensing information held in advance to the base station 100 in synchronization with the start signal received by the reception circuit 230 ₁ .

5 shows a configuration example of a feed system of the base station 100 and the first terminal 200 ₁ in FIG. In FIG. 5, the same parts as those in FIG.

  In the base station 100, the power feeding circuit 110 includes an excitation circuit 112 and a power supply coil 114. The power supply coil 114 includes an excitation side coil 120 and a power supply side coil 122. The excitation circuit 112 performs control to generate a magnetic field by the excitation side coil 120. The power supply side coil 122 generates radio waves according to the magnetic field generated by the excitation side coil 120.

The first terminal 200 ₁ can include a power supply circuit 280 ₁ , a switch 282 ₁ , a switch control unit 284 ₁ , and a timer 286 ₁ in addition to the power reception circuit 210 ₁ , the reception circuit 230 ₁ , and the transmission circuit 250 ₁ . A reception detection signal indicating whether or not the start signal has been received by the reception circuit 230 ₁ is input to the switch control unit 284 ₁ and the timer 286 ₁ . The power receiving circuit 210 ₁ includes a power receiving side coil 212 ₁ , a rectifying / smoothing circuit 214 ₁ , and a regulator 216 ₁ .

Power receiving coil 212 ₁ converts into an electric signal by receiving a radio wave feeder coil 122 of the base station 100 is caused. Rectifying and smoothing circuit 214 ₁ smoothes the signal from the power receiving coil 212 _1. The regulator 216 ₁ adjusts the signal smoothed by the rectifying and smoothing circuit 214 ₁ . The output signal of the regulator 216 ₁ performs switch control of the switch 282 ₁ .

The switch 282 ₁ performs control to supply power to the power supply circuit 280 ₁ to the load circuit 290 ₁ including the reception circuit 230 ₁ and the transmission circuit 250 ₁ or to stop supply of the power. The timer 286 ₁ starts counting with the reception detection signal as a trigger, and notifies the switch control unit 284 ₁ that a given timeout time has elapsed. The switch control unit 284 ₁ can perform control to stop power supply from the power supply circuit 280 ₁ to the load circuit 290 ₁ by the switch 282 ₁ when the timer 286 ₁ is notified of the elapse of the timeout time. In this way, the first terminal 200 ₁ is adapted to transition from the sleep state to the sleep-out state can transition from the sleep-out state to the sleep state.

6 shows an example of the configuration of the base station 100 of FIG. 4 and the first terminal 200 ₁ in the data communication system. In FIG. 6, the same parts as those in FIG.

  In base station 100, transmission circuit 130 includes a clock generation unit 132, a pulse generation unit 134, and an RF transmission unit 136. The reception circuit 150 includes an RF reception unit 152, an OFDM demodulation unit 154, and a carrier demodulation unit 156.

The clock generator 132 generates a reference clock, and the pulse generator 134 generates a pulse signal based on the reference clock. The RF transmitter 136 can transmit the pulse signal as a start signal to the _first to _Nth terminals 200 ₁ to 200 N via the antenna 180.

  In the base station 100, a signal received via the antenna 180 is received by the RF receiving unit 152 (receiving unit in a broad sense), and then the OFDM demodulating unit 154 demodulates the OFDM signal. The carrier demodulator 156 demodulates the signal of each carrier to obtain received data. Here, it can be said that the OFDM demodulator 154 and the carrier demodulator 156 are reception processing units.

  FIG. 7 shows a detailed configuration example of the receiving circuit 150 of the base station 100 of FIG. 7, the same parts as those in FIG. 6 are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

  The OFDM demodulator 154 includes an FFT processor 190, a demodulator 192, and a frame extractor 194. The FFT processing unit 190 performs an FFT process on the OFDM signal received by the RF receiving unit 152, and the demodulation unit 192 demodulates the signal into each carrier frequency. The frame extraction unit 194 extracts a frame of a signal from each terminal and notifies the FFT processing unit 190 of the head of the frame.

  The carrier demodulating unit 156 includes a demapping unit 196, and demaps the signal of each carrier frequency demodulated by the demodulating unit 192 according to the phase modulation (BPSK, QPSK, etc.) performed at each terminal.

  Furthermore, the base station 100 includes a CRC (Cyclic Redundancy Check) check unit 198, and performs a CRC check based on the signal demodulated by the carrier demodulation unit 156. When it is detected by the CRC check that the data has been normally received, the data is supplied as normal received data to a subsequent processing unit (circuit, application software). When an abnormality is detected by the CRC check, a control signal for making a retransmission request to the transmission circuit 130 may be output.

  Returning to FIG. 6, the description will be continued.

In the first terminal 200 ₁ , the reception circuit 230 ₁ includes an RF reception unit 232 ₁ and a timing adjustment unit 234 ₁ . A signal received via the antenna 296 ₁ is subjected to reception processing by the RF receiver 232 ₁ . When reception of a start signal from the base station 100 is detected in the RF reception unit 232 ₁ (reception unit in a broad sense), the reception detection signal is activated. The timing adjustment unit 234 ₁ is configured so that signals from the _first to _N-th terminals 200 ₁ to 200 _N are detected as OFDM signals in the base station 100 based on the detection timing of the start signal in the RF reception unit 232 ₁ . adjusting the transmission timing of the transmission circuit 250 _1. More specifically, the timing adjusting unit 234 _1, to be able to modulate the symbol rate of each user the same west, with orthogonal frequency to each carrier.

The transmission circuit 250 ₁ includes a sensor unit 260 ₁ , a modulation unit 270 ₁ , and an RF transmission unit 272 ₁ . The sensor unit 260 ₁ includes a sensor 262 ₁ and a memory 264 ₁ . Sensor 262 _1, for example can employ a temperature sensor and humidity sensor, temperature information and humidity information as sensing information of the sensor 262 ₁ is stored in the memory 264 _1.

The modulation unit 270 ₁ performs phase modulation (BPSK, QPSK, 8-phase PSK) on the data bit string corresponding to the sensing information stored in the memory 264 ₁ . The RF transmission unit 272 ₁ transmits the signal modulated by the modulation unit 270 ₁ via the antenna 296 ₁ at the timing adjusted by the timing adjustment unit 234 ₁ . Here, the RF transmission unit 272 ₁ (transmission unit in a broad sense) is a signal after phase modulation by the modulation unit 270 ₁ as a signal having a carrier frequency that is one time the reference frequency fc in the first terminal 200 _1. Send. The second terminal 200 ₂ in carrier frequency 2 × fc, the third terminal 2003, the carrier frequency is 3 × fc, · · ·, the carrier frequency at terminal 200 _N of the N becomes N × fc.

2.2 Operation Example Next, an operation example of the base station 100 and the first terminal 200 _1.

  FIG. 8 shows a flowchart of an operation example of the base station 100.

  The base station 100 includes a central processing unit (hereinafter referred to as a CPU) and a program memory (not shown), and the CPU performs processing corresponding to the program stored in the program memory to control each unit of the base station 100. By controlling, the processing shown in FIG. 8 can be realized.

First, the base station 100 monitors whether or not there is a request for obtaining sensing information (signal request) of the _first to _Nth terminals 200 ₁ to 200 N from a higher-level application executed by the CPU (step S500: N). When there is a sensing information acquisition request from the upper application (step S500: Y), the base station 100 first transmits a wake-up signal as described above (step S501). When a predetermined time has elapsed after transmitting the wake-up signal, the base station 100 transmits the start signal as described above (step S502).

After that, the base station 100 waits for responses from the _first to _N-th terminals 200 ₁ to 200 _N , and performs a reception process of signals including sensing information from each terminal (step S503). As a result, when it is not detected that the signals from the _first to _N-th terminals 200 ₁ to 200 _N have been normally received (step S504: N), the process returns to step S502 and the start signal is transmitted again. . On the other hand, when it is detected in step S504 that signals from the _first to _N-th terminals 200 ₁ to 200 _N have been normally received (step S504: Y), a CRC check is performed (step S505).

  If it is detected as a result of the CRC check that the received data is abnormal (step S505: N), the process returns to step S502. As a result of the CRC check, when it is detected that the received data is normal (step S505: Y), the received data is supplied to the upper application side (step S506), and the series of processing ends (end).

Figure 9 shows a flow diagram of a first operation example of the terminal 200 _1.

The first terminal 200 ₁ has a program memory, not CPU and illustrated, the CPU is by controlling the first terminal 200 ₁ of each part by performing the processing corresponding to the program stored in the program memory, FIG. 9 can be realized.

First terminal 2001 _first waits for reception of a wakeup signal in the sleep state (step S600: N). At step S600, the when the received wake-up signal is detected (step S600: Y), the first terminal 200 ₁ proceeds to the sleep-out state as described above (step S601).

Thereafter, the first terminal 200 ₁ detects whether it has received the start signal (step S602). In step S602, when reception of the start signal is not detected (step S602: N), it is determined whether or not a predetermined time has elapsed after the previous start signal reception timing or the transition timing to the sleep-out state ( Step S603). If it is not determined in step S603 that the predetermined time has elapsed (step S603: N), the process returns to step S602. In step S603, when it is determined that the predetermined time has elapsed (step S603: Y), the first terminal 200 ₁ is changed to the sleep mode as described above (step S604), the flow returns to step S600 (RETURN).

On the other hand, when the reception of the start signal is detected in step S602, with respect to:: (Y step S605), the base station 100 the sensing information (step S602 Y), when the sensing information in the memory 264 ₁ is stored Then, the process proceeds to step S603 (step S606). In step S605, when the sensing information is not stored in the memory 264 ₁ (step S605: N), the sensor 262 ₁ stores the sensing information in the memory 264 ₁ , and proceeds to step S603 (step S607).

FIG. 10 shows an operation explanatory diagram of the _first to _Nth terminals 200 ₁ to 200 N in the present embodiment.

In FIG. 10, it is assumed that the _first to _Nth terminals 200 ₁ to 200 _N are in a sleep state. Here, at the timing TG1, the base station 100 transmits a wake-up signal to the terminal 200 ₁ of the first to N, the first and second terminal ₂₀₀ 1, 200 ₂ receives a wake-up signal Has entered sleep-out state. At this time, it is assumed that the _third to _N-th terminals 200 ₃ to 200 _N cannot receive the wake-up signal for some reason.

  In FIG. 10, unlike the process of FIG. 9, it is assumed that sensing information is acquired immediately after the transition to the sleep-out state.

Thereafter, the base station 100, the wake-up signal, and transmits a start signal periodically, at the timing TG2, the terminal 200 of the first and _second, 200 ₂ detects the reception of the start signal, obtained The transmission of sensing information to the base station 100 is started. In this timing TG2, the third terminal 200 ₃ detects the reception of the wake-up signal, a third terminal 200 ₃ is in sleep-out state, waiting for a detection timing of the reception of the next start signal.

At timing TG3, when the _first to _third terminals 200 ₁ to 200 ₃ detect reception of the start signal, the acquired sensing information is transmitted to the base station 100. In this timing TG3, fourth terminal 200 ₄ detects the reception of the wake-up signal, a fourth terminal 200 ₄ in sleep-out state, waiting for a detection timing of the reception of the next start signal.

As described above, each terminal can separately detect reception of a wakeup signal, and when detecting reception of the next start signal, each terminal repeatedly transmits sensing information each time a start signal is received from the base station 100. When it is detected in the host application of the base station 100 that the sensing information has been acquired from all of the _first to _Nth terminals 200 ₁ to 200 _N (timing TG10), a start signal is transmitted from the base station 100 thereafter. Disappear. Accordingly, the _first to _N-th terminals 200 ₁ to 200 _N shift to the sleep state at timing TG20 after a predetermined time has elapsed since timing TG10.

  FIG. 11 is a sequence diagram illustrating an operation example of the wireless communication system according to the present embodiment. In FIG. 11, the vertical axis indicates the time flow.

First, when there is a request for obtaining sensing information from an upper application processed by the CPU of the base station 100, a signal request is made to the power supply circuit 110 of the base station 100 (SQ1). The power supply circuit 110 of the base station 100 that has received the signal request transmits a wakeup signal to the _first to _Nth terminals 200 ₁ to 200 _N (SQ2). Note that the transmission circuit 130 of the base station 100 may transmit the same signal as the start signal as a wakeup signal.

The _first to _N-th terminals 200 ₁ to 200 N that have received the wake-up signal transition from the sleep state to the sleep-out state (SQ 3 _{1 to} SQ 3 _N ).

The base station 100 that has transmitted the wakeup signal transmits a start signal to the _first to _Nth terminals 200 ₁ to 200 _N after a predetermined time (SQ4). The _first to _Nth terminals 200 ₁ to 200 N that have received the start signal transmit sensing information as signals of carrier frequencies orthogonal to each other in synchronization with the start signal (SQ5). As a result, the base station 100 can receive signals from the _first to _N-th terminals 200 ₁ to 200 _N as OFDM signals.

The base station 100 demodulates the OFDM signals from the _first to _Nth terminals 200 ₁ to 200 _N (SQ6), and performs a CRC check performed on the received data bit string (SQ7). Here, when a reception abnormality is detected as a result of the CRC check, the base station 100 requests the _first to _Nth terminals 200 ₁ to 200 _N to retransmit the sensing information (SQ8). This retransmission request signal can be a start signal. The _first to _N-th terminals 200 ₁ to 200 _{N that} have received the start signal transmit sensing information as signals of carrier frequencies orthogonal to each other in synchronization with the start signal (SQ9). The base station 100 receives signals from the _first to _N-th terminals 200 ₁ to 200 _N as OFDM signals.

The base station 100 demodulates the OFDM signals from the _first to _Nth terminals 200 ₁ to 200 _N (SQ10), and performs a CRC check performed on the received data bit string (SQ11). Here, when normal reception is detected as a result of the CRC check, the base station 100 supplies the received data to the upper application (SQ12).

  As described above, in the present embodiment, transmission is performed at carrier frequencies that are orthogonal to each other by, for example, making the symbol rate of each terminal the same, so that it is not necessary for each terminal to perform IFFT processing. Can be greatly simplified, and low power consumption can be achieved. In addition, the base station can receive data from a plurality of terminals at a time by FFT processing or the like by a known OFDM signal reception process. Therefore, communication management of a plurality of terminals can be simplified in the base station.

  For example, in a sensor network, a sensor is mounted on each terminal having a wireless communication function, and in response to a start signal (trigger signal) from the base station, each terminal can simultaneously acquire sensing information at the base station. In this case, the base station can acquire sensing information of each terminal position in real time, and does not require complicated processing for each terminal.

3. Modified Example In this embodiment, each terminal has been described as having a power supply circuit. However, in the modified example of this embodiment, the carrier frequency is transmitted to the base station by the electromotive force generated by the power supply control from each base station. Transmit signals orthogonal to each other.

Figure 12 shows a block diagram of a first configuration example of a terminal 200 ₁ in this variation. In FIG. 12, the same parts as those in FIG.

The first terminal 200 ₁ is the first terminal 200 differs from the _first 5 in this modification, that the output voltage of the regulator 216 ₁ generated by the power receiving circuit 210 ₁ is used as a power supply voltage of the load circuit 290 ₁ It is.

By doing so, the receiving circuit 230 ₁ and the transmitting circuit 250 ₁ of the load circuit 290 ₁ can receive signals from the base station 100 and transmit signals to the base station 100 by the electromotive force generated in the power receiving circuit 210 _1. Become. Therefore, according to this modification, the first terminal 200 ₁ configured to further simplify, power consumption can be reduced.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the gist of the present invention.

  In the invention according to the dependent claims of the present invention, a part of the constituent features of the dependent claims can be omitted. Moreover, the principal part of the invention according to one independent claim of the present invention may be made dependent on another independent claim.

The figure which shows the outline | summary of a structure of the radio | wireless communications system in this embodiment. 2 (A), 2 (B), and 2 (C) are operation explanatory views of the wireless communication system of the present embodiment. Explanatory drawing of the OFDM signal in this embodiment. The figure which shows the outline | summary of a structure of the base station and 1st terminal in this embodiment. The figure which shows the structural example of the electric power feeding system of the base station of FIG. 4, and a 1st terminal. The figure which shows the structural example of the data communication system of the base station of FIG. 4, and a 1st terminal. The figure which shows the detailed structural example of the receiving circuit of the base station of FIG. The flowchart of the operation example of the base station of this embodiment. The flowchart of the operation example of the 1st terminal of this embodiment. Operation | movement explanatory drawing of the 1st-Nth terminal in this embodiment. The sequence diagram which shows the operation example of the radio | wireless communications system of this embodiment. The block diagram of the structural example of the 1st terminal in this modification.

Explanation of symbols

10 wireless communication system, 100 base station, 110 feeding circuit,
112 excitation circuit, 114 power supply circuit, 120 excitation side coil,
122 power supply side coil, 130 transmission circuit, 132 clock generator,
134 Pulse generator, 136, 272 ₁ RF transmitter, 150 receiver circuit,
152, 232 ₁ RF receiver, 154 OFDM demodulator,
156 Carrier demodulation unit, 180, 296 ₁ antenna, 190 FFT processing unit,
192 demodulation unit, 194 frame extraction unit, 196 demapping unit,
198 CRC check section, 200 ₁ to 200 _{N first} to _Nth terminals,
210 _{1 power} reception circuit, 212 _{1 power} reception side coil, 214 ₁ rectification smoothing circuit,
216 ₁ regulator, 230 ₁ receiving circuit, 234 ₁ timing adjustment unit,
250 ₁ transmission circuit, 260 ₁ sensor unit, 262 ₁ sensor,
H.264 ₁ memory, 270 ₁ modulator, 280 ₁ power supply circuit,
282 ₁ switch, 284 ₁ switch controller, 286 ₁ timer,
290 ₁ load circuit

Claims (25)

A base station,
First to Nth terminals (N is an integer of 2 or more),
The first to N-th terminals are
Simultaneously transmit signals with carrier frequencies orthogonal to each other to the base station,
The base station is
A wireless communication system, wherein reception processing is simultaneously performed on signals from the first to Nth terminals. In claim 1,
The first to N-th terminals are
The signal after the first modulation processing is transmitted to the base station all at once,
The base station is
A radio communication system, wherein a first demodulation process corresponding to the first modulation process is performed on a signal obtained by performing a predetermined demodulation process on the signals from the first to Nth terminals. . In claim 1 or 2,
The base station is
Transmitting a start signal to the first to Nth terminals;
The first to N-th terminals are
A radio communication system, wherein signals having carrier frequencies orthogonal to each other are transmitted simultaneously to the base station in synchronization with the start signal. In claim 3,
The base station is
Prior to transmission of the start signal, a wakeup signal is transmitted to the first to Nth terminals,
The first to N-th terminals are
A wireless communication system, wherein the wireless communication system shifts to a sleep-out state by receiving the wake-up signal when in a sleep state, and transmits a signal to the base station in the sleep-out state. In claim 3,
The base station is
Prior to transmission of the start signal, a wakeup signal is transmitted to the first to Nth terminals,
The first to N-th terminals are
A radio communication system, wherein an electromotive force is generated based on the wake-up signal, and signals having carrier frequencies orthogonal to each other are transmitted to the base station by the electromotive force. In any one of Claims 1 thru | or 5,
When the reference frequency is fc,
The j-th terminal (1 ≦ j ≦ N, j is an integer) is
A radio communication system, wherein a signal having a carrier frequency of j × fc is transmitted to the base station. In any one of Claims 1 thru | or 6.
Each of the first to Nth terminals is
A radio communication system, wherein a phase-modulated signal is transmitted to the base station. In any one of Claims 1 thru | or 7,
Each of the first to Nth terminals is
Transmitting the generated signal to the base station without performing inverse fast Fourier transform on the signal to be transmitted;
The base station is
A radio communication system, wherein a reception signal is generated from a signal from the first to Nth terminals by a fast Fourier transform process. In any one of Claims 1 thru | or 8.
A radio communication system, wherein signals transmitted by the first to Nth terminals form an Orthogonal Frequency Division Multiplexing (OFDM) signal. A base station for receiving signals from first to N-th (N is an integer of 2 or more) terminals,
A receiving unit that receives signals transmitted simultaneously to the base station by the first to Nth terminals, the carrier frequency of each terminal being orthogonal to each other;
And a reception processing unit that performs reception processing on signals from the first to Nth terminals. In claim 10,
The first to Nth terminals transmit signals after the first modulation process all at once,
A base station that performs a first demodulation process corresponding to the first modulation process on a signal obtained by performing a predetermined demodulation process on signals from the first to N-th terminals. In claim 10 or 11,
Transmitting a start signal to the first to Nth terminals;
A base station, wherein the first to N-th terminals receive signals in which signals having carrier frequencies orthogonal to each other are transmitted simultaneously in synchronization with the start signal. In claim 12,
Prior to transmission of the start signal, a wakeup signal is transmitted to the first to Nth terminals,
The base station, wherein the first to Nth terminals in a sleep state are shifted to a sleep-out state in which a signal is transmitted to the base station by the wakeup signal. In claim 12,
Prior to transmission of the start signal, a wakeup signal is transmitted to the first to Nth terminals,
A base that causes the first to N-th terminals to generate an electromotive force based on the wake-up signal, and causes the base station to transmit signals having carrier frequencies orthogonal to each other based on the electromotive force. Bureau. In any of claims 10 to 14,
When the reference frequency is fc,
A base station that receives a signal in which a carrier frequency of a j-th terminal (1 ≦ j ≦ N, j is an integer) is j × fc. In any of claims 10 to 15,
From each of the first to Nth terminals, a signal generated without performing an inverse fast Fourier transform process on a signal to be transmitted is received, and a received signal is obtained by performing a fast Fourier transform process on the signal. A base station characterized by generating. In any of claims 10 to 16,
An orthogonal frequency division multiplexing (OFDM) signal is formed by signals transmitted by the first to Nth terminals. A terminal of a wireless communication system including a base station and first to Nth (N is an integer of 2 or more) terminals,
A receiving unit for receiving a start signal from the base station;
A terminal comprising: a transmission unit configured to transmit, to the base station, signals in which carrier frequencies of the first to N-th terminals are orthogonal to each other in synchronization with the start signal. In claim 18,
The transmitter is
Transmitting the first modulated signal to the base station;
The base station is
A terminal that performs a first demodulation process corresponding to the first modulation process on a signal obtained by performing a predetermined demodulation process on signals from the first to Nth terminals. In claim 18 or 19,
Prior to transmission of the start signal, a wake-up signal is received from the base station,
In the sleep state, the terminal shifts to a sleep-out state in which a signal is transmitted to the base station by receiving the wake-up signal. In claim 18 or 19,
Prior to transmission of the start signal, a wake-up signal is received from the base station,
A terminal that generates an electromotive force based on the wake-up signal and transmits a signal to the base station based on the electromotive force. A device according to any one of claims 18 to 21.
When the reference frequency is fc,
The transmitter is
A terminal that transmits a signal having a carrier frequency j (1 ≦ j ≦ N, j is an integer) × fc associated with the terminal. 23. Any one of claims 18-22.
The transmitter is
A terminal that transmits a phase-modulated signal to the base station. 24.
Transmitting the generated signal to the base station without performing inverse fast Fourier transform on the signal to be transmitted;
The base station is
A terminal that generates a received signal from a signal from the first to Nth terminals by a fast Fourier transform process. 25. Any one of claims 18 to 24.
A signal transmitted by the first to Nth terminals forms an Orthogonal Frequency Division Multiplexing (OFDM) signal.

Images