JP5391460B2 - TERMINAL DEVICE, RADIO DEVICE FOR RADIO COMMUNICATION WITH THE SAME, AND RADIO COMMUNICATION SYSTEM INCLUDING THE SAME - Google Patents

Description

  The present invention relates to a terminal device, a wireless device that performs wireless communication with the terminal device, and a wireless communication system including them.

  Wireless LAN (Local Area Network) is widely used in homes and offices. Along with the widespread use of wireless LANs, many access points (APs) are installed, but these APs are normally used with the power turned on even if no communication data is generated.

  Since such an “already-on” AP has not been used for a majority of the time, power is wasted.

  In the sensor network, a method of waking up a data transmission destination only when communication using a wake-up receiver is necessary is being studied.

  In Non-Patent Document 1, when a wireless LAN channel having the same frequency is observed using 802.15.4 sensor motes that consume lower power than a wireless LAN card and radio waves from the transmission source are detected, A method for waking up a card has been proposed.

  Patent Documents 1 and 2 and Non-Patent Document 2 propose a method of waking up a wireless LAN card using a wakeup receiver that consumes lower power.

  Further, in Patent Documents 1 and 2 and Non-Patent Document 2, the frequency of the wake-up signal is different from the frequency of the wireless LAN, so two antennas are required.

  Further, Patent Document 3 proposes a frequency spreading method for performing frequency spreading without changing the envelope of the signal so as to satisfy FCC regulation (band regulation) in ISM band.

Special table 2007-526655 gazette International Publication No. 04/100503 Pamphlet US Patent Application Publication No. 2007/0253468

Nilesh Mishra, Kameswari Chebrolu, Bhaskaran Raman, Abhinav Pathak, Wakeon WLAN, WWW 2006. Shigeki Ishida, Makoto Suzuki, Takashi Morito, Hiroyuki Morikawa, Multistage Wakeup Mechanism for Low Receiving Standby Power Wireless Communication, IEICE technical report, information networks 107 (525), 355-360, 2008-02-28.

  However, when transmitting a wireless LAN signal and a wake-up signal with one antenna, how to suppress erroneous detection of the wake-up signal becomes a big problem.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide a terminal device capable of suppressing erroneous detection of a wakeup signal.

  Another object of the present invention is to provide a wireless device capable of suppressing erroneous detection of a wakeup signal.

  Furthermore, another object of the present invention is to provide a wireless communication system including a terminal device and a wireless device that can suppress erroneous detection of a wakeup signal.

  According to the embodiment of the present invention, the terminal device includes an antenna, a calculation unit, a signal generation unit, and a transmission unit. The antenna is used for transmitting and receiving wireless communication signals. The computing means performs Manchester encoding on the identification information of the wireless device to be woken up in response to a request for wireless communication. The signal generation means generates an on / off control signal using the Manchester encoded identification information, multiplies the generated on / off control signal by a carrier signal having a frequency used for wireless communication, and generates a wake-up signal. Generate. The transmission means performs carrier sense on a channel having a frequency used for wireless communication, and transmits a wakeup signal using an antenna when the channel is in an idle state. Then, the transmission means transmits the wakeup signal at a transmission rate at which the off period of the wakeup signal corresponding to the off period in the on / off control signal is shorter than the shortest time for determining the idle state of the channel.

  According to the embodiment of the present invention, the wireless device includes an antenna, wireless communication means, receiving means, identification means, and determination means. The antenna is used for transmitting and receiving wireless communication signals. The wireless communication means transmits / receives a wireless communication signal to / from the terminal device using the antenna, and shifts to a sleep state when wireless communication with the terminal device is not performed for a certain period. The receiving means receives a radio wave via an antenna on a channel having a frequency used for transmission / reception of a wireless communication signal. The identifying unit identifies whether the received radio wave received by the receiving unit is a wireless communication signal or a wake-up signal generated by Manchester encoding the first identification information for identifying the wireless device. When the received radio wave is a wake-up signal, the determination unit determines whether the second identification information obtained by decoding the received radio wave matches the first identification information, and the second identification information is When it matches the first identification information, the wireless communication means that has shifted to the sleep state is activated.

  Furthermore, according to the embodiment of the present invention, the wireless communication system includes a terminal device and a wireless device. The wireless device performs wireless communication with the terminal device. The terminal device includes the terminal device according to claim 1 or 2, and the wireless device includes the wireless device according to any one of claims 3 to 9.

  In the terminal device according to the embodiment of the present invention, in response to a request for wireless communication, the identification information of the wireless device to be woken up is Manchester encoded, and the on / off control generated using the Manchester encoded identification information A wake-up signal is generated by multiplying the signal by the carrier signal. When the channel is in an idle state, the wake-up signal is transmitted at a transmission rate in which the off period of the wake-up signal is shorter than the shortest time for determining the channel idle state. As a result, the off period of the wakeup signal is a period in which two “0” s continue in the on / off control signal at the longest, and a signal other than the wakeup signal is transmitted during the transmission of the wakeup signal. The wake-up signal is transmitted correctly to the wireless device that wakes up. Further, the wireless device to be woken up accurately receives the radio wave composed of the wake-up signal, and detects the wake-up signal transmitted from the terminal device.

  Therefore, erroneous detection of the wakeup signal can be suppressed.

  The wireless device according to the embodiment of the present invention discriminates a wake-up signal from a wireless LAN signal based on the received radio wave, and detects the wake-up signal when it is identified that the received radio wave is a wake-up signal.

  Therefore, erroneous detection of the wakeup signal can be suppressed in the wireless device.

  Furthermore, a wireless communication system according to an embodiment of the present invention includes the terminal device and the wireless device described above. As a result, the wake-up signal is not transmitted simultaneously with other wireless LAN signals, but is accurately transmitted to the wireless device to wake up. Further, the wireless device to be woken up accurately receives the radio wave composed of the wake-up signal, and detects the wake-up signal transmitted from the terminal device.

  Therefore, erroneous detection of the wakeup signal can be suppressed.

1 is a schematic diagram of a radio communication system according to an embodiment of the present invention. It is a block diagram of the terminal device shown in FIG. It is a block diagram of the wake-up signal transmitter shown in FIG. It is a block diagram of the access point shown in FIG. It is a block diagram of the wake-up signal receiver shown in FIG. It is a conceptual diagram for demonstrating the method to produce | generate a wakeup signal. It is a conceptual diagram of the envelope of a received radio wave. It is a conceptual diagram of the wake-up signal and the signal by wireless LAN. 3 is a flowchart for explaining an operation in the wireless communication system shown in FIG. 1. FIG. 5 is another configuration diagram of the wake-up signal receiver shown in FIG. 4. 6 is another flowchart for explaining the operation of the wireless communication system shown in FIG. 1. It is the schematic of the other radio | wireless communications system by embodiment of this invention. It is a block diagram of the access point shown in FIG.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic diagram of a radio communication system according to an embodiment of the present invention. Referring to FIG. 1, a wireless communication system 100 according to an embodiment of the present invention includes a terminal device 10 and an access point 20 that is a wireless device.

  The terminal device 10 performs wireless communication with the access point 20 in accordance with a wireless LAN communication method. When the terminal device 10 does not receive a beacon frame from the access point 20, the terminal device 10 determines that the access point 20 is in a sleep state. Thereafter, when starting the wireless communication, the terminal device 10 transmits a wake-up signal to the access point 20 by a method described later, and activates the access point 20.

  The access point 20 is connected to the network 30 by a wired cable 40. Then, the access point 20 relays communication between the terminal device 10 and the network 30. More specifically, the access point 20 receives communication data from the terminal device 10 and transmits the received communication data to the network 30 via the wired cable 40. The access point 20 receives communication data from the network 30 via the wired cable 40 and transmits the received communication data to the terminal device 10 by wireless communication.

  When the access point 20 does not receive a packet from the terminal device 10 for a certain period, it shifts to the sleep state. When the access point 20 receives a radio wave from the terminal device 10 in the sleep state, the access point 20 identifies whether the received radio wave is a wake-up signal or a wireless LAN signal by a method described later, and the received radio wave wakes up. When the identification information included in the wake-up signal coincides with its own identification information, it shifts from the sleep state to the activation state. Thereafter, the access point 20 relays communication between the terminal device 10 and the network 30.

  FIG. 2 is a block diagram of the terminal device 10 shown in FIG. Referring to FIG. 2, terminal device 10 includes an antenna 11, a wakeup signal transmitter 12, a wireless LAN card 13, a CPU (Central Processing Unit) / display unit 14, and a power supply 15.

  The wakeup signal transmitter 12 and the wireless LAN card 13 are connected to the antenna 11.

  The wake-up signal transmitter 12 is driven by power supplied from the power source 15. When the wake-up signal transmitter 12 receives an instruction signal Wup for waking up the access point 20 from the wireless LAN card 13, the wake-up signal transmitter 12 determines the frequency of the wireless LAN signal (= 2.4 GHz band frequency) by the method described later. A wakeup signal WK having the same frequency is generated, and the generated wakeup signal WK is transmitted to the access point 20 via the antenna 11.

  The wireless LAN card 13 is driven by power supplied from the power supply 15. The wireless LAN card 13 periodically receives beacon frames from the access point 20. The wireless LAN card 13 establishes a wireless communication path with the access point 20 based on various information included in the beacon frame, and performs wireless communication with the access point 20 via the antenna 11. More specifically, the wireless LAN card 13 receives a packet addressed to the terminal device 10 from the access point 20 and outputs the received packet to the CPU / display unit 14. Further, the wireless LAN card 13 receives a packet addressed to the access point 20 from the CPU / display unit 14 and transmits the received packet to the access point 20 via the antenna 11.

  When the wireless LAN card 13 does not receive a beacon frame from the access point 20, the wireless LAN card 13 determines that the access point 20 is in a sleep state. Thereafter, when starting wireless communication with the access point 20, the wireless LAN card 13 generates an instruction signal Wup for waking up the access point 20 and outputs the instruction signal Wup to the wakeup signal transmitter 12.

  The CPU / display unit 14 is driven by the electric power supplied from the power supply 15. The CPU / display unit 14 receives a packet from the wireless LAN card 13 and provides the contents of the packet as visual information to the user of the terminal device 10 according to the type of the received packet.

  In addition, the CPU / display unit 14 generates a packet addressed to the access point 20 and outputs the generated packet to the wireless LAN card 13.

  FIG. 3 is a block diagram of the wake-up signal transmitter 12 shown in FIG. Referring to FIG. 3, the wakeup signal transmitter 12 includes an ID generation unit 121, a calculation unit 122, an on / off control unit 123, a frequency spreading unit 124, a multiplier 125, an amplification unit 126, Transmission means 127.

  When receiving the instruction signal Wup from the wireless LAN card 13, the ID generation unit 121 calculates a hash value of the MAC (Media Access Control) address of the access point 20, for example, and generates the identification information ID 20 of the access point 20. Then, the ID generation unit 121 outputs the generated identification information ID20 to the calculation unit 122.

  The computing means 122 performs Manchester encoding on the identification information ID 20 received from the ID generation means 121, and outputs the Manchester encoded identification information ID 20 to the on / off control means 123.

  The on / off control means 123 generates an on / off control signal based on the Manchester-encoded identification information ID 20 and outputs the generated on / off control signal to the multiplier 125.

  The frequency spreading means 124 generates a carrier signal by spreading the frequency in a frequency band used for signal transmission / reception by the wireless LAN by a method described later, and outputs the generated carrier signal to the multiplier 125.

  Multiplier 125 multiplies the on / off control signal received from on / off control means 123 and the carrier signal received from frequency spreading means 124 to generate wakeup signal WK, and generates the generated wakeup signal WK. Output to amplifying means 126.

  Amplifying means 126 amplifies wakeup signal WK and outputs the amplified signal to transmitting means 127. The transmission means 127 performs carrier sense on the channel for transmitting the wakeup signal WK. When the energy received from the channel is equal to or less than the threshold RSSI_th, the transmission unit 127 determines that the channel is in an idle state, and transmits the wakeup signal WK. Transmit to the access point 20 via the antenna 11. Note that the threshold RSSI_th is set to −90 dBm, for example.

  As described above, the terminal device 10 transmits and receives a wireless LAN signal using one antenna 11 and transmits a wakeup signal WK having the same frequency as the wireless LAN signal.

  FIG. 4 is a block diagram of the access point 20 shown in FIG. Referring to FIG. 4, access point 20 includes an antenna 21, a wireless LAN card 22, a CPU 23, a network connection card 24, power supplies 25 and 26, and a wakeup signal receiver 27.

  The wireless LAN card 22 and the wakeup signal receiver 27 are connected to the antenna 21.

  The wireless LAN card 22 is activated when power is supplied from the power supply 25. Then, the wireless LAN card 22 periodically transmits a beacon frame. When a wireless communication path is established with the terminal device 10, the wireless LAN card 22 receives a packet from the terminal device 10 by wireless communication via the antenna 21, and outputs the received packet to the CPU 23. The wireless LAN card 22 receives a packet from the CPU 23 and transmits the received packet to the terminal device 10 via the antenna 21 by wireless communication.

  Further, when the wireless LAN card 22 does not receive a packet from the terminal device 10 for a certain period, the wireless LAN card 22 shifts to a sleep state by stopping the power from the power supply 25. The wireless LAN card 22 is activated when power is supplied from the power supply 25 after entering the sleep state, and performs wireless communication with the terminal device 10 via the antenna 21.

  The CPU 23 is activated when power is supplied from the power supply 25. The CPU 23 receives the packet from the wireless LAN card 22 and outputs the received packet to the network connection card 24. Further, the CPU 23 receives a packet from the network connection card 24 and outputs the received packet to the wireless LAN card 22.

  Further, when the CPU 23 does not receive a packet from the terminal device 10 via the wireless LAN card 22 for a certain period, the CPU 23 generates an instruction signal POFF for stopping power supply and outputs the instruction signal POFF to the power supply 25. Then, when power is not supplied from the power supply 25, the CPU 23 shifts to a sleep state. Thereafter, when the power is supplied from the power supply 25, the CPU 23 is activated and relays the packet between the wireless LAN card 22 and the network connection card 24.

  The network connection card 24 is activated when power is supplied from the power supply 25. Then, the network connection card 24 transmits the packet received from the CPU 23 to the network 30 via the wired cable 40. Further, the network connection card 24 receives a packet from the network 30 via the wired cable 40 and outputs the received packet to the CPU 23.

  Furthermore, when power is not supplied from the power supply 25, the network connection card 24 shifts to a sleep state. Thereafter, when power is supplied from the power supply 25, the network connection card 24 is activated.

  The power supply 25 supplies power to the wireless LAN card 22, the CPU 23, and the network connection card 24. When the power supply 25 receives the instruction signal POFF from the CPU 23, the power supply 25 stops supplying power to the wireless LAN card 22, the CPU 23, and the network connection card 24. Thereafter, upon receiving the wake-up instruction signal Wu_comd from the wake-up signal receiver 27, the power supply 25 supplies power to the wireless LAN card 22, the CPU 23, and the network connection card 24.

  The power supply 26 supplies power to the wakeup signal receiver 27. The wake-up signal receiver 27 receives a radio wave via the antenna 21 and identifies whether the received radio wave received is a wake-up signal WK or a wireless LAN signal by a method described later.

  Then, when the wakeup signal receiver 27 identifies that the received radio wave is the wakeup signal WK, the wakeup signal receiver 27 determines whether or not the identification information obtained by decoding the received radio wave matches the identification information of the access point 20. To do.

  The wakeup signal receiver 27 generates a wakeup instruction signal Wu_comd and outputs it to the power supply 25 when it is determined that the identification information obtained by decoding the received radio wave matches the identification information of the access point 20.

  In this way, the access point 20 transmits and receives a wireless LAN signal using one antenna 21 and receives a wake-up signal WK having the same frequency as the wireless LAN signal.

  In the embodiment of the present invention, the “sleep state” is a state in which the wireless LAN card 22, the CPU 23, and the network connection card 24 are not supplied with power from the power source 25, and the wake-up signal receiver 27 is In this state, power is supplied from the power source 26. That is, the “sleep state” means that the wireless LAN card 22 cannot perform wireless communication with the terminal device 10 and the network connection card 24 cannot communicate with the network 30, but the wake-up signal receiver 27 is not connected to the terminal. This means a state in which the wakeup signal WK can be received from the device 10.

  FIG. 5 is a block diagram of the wake-up signal receiver 27 shown in FIG. Referring to FIG. 5, wakeup signal receiver 27 includes BPF (Band Pass Filter) 271, envelope detection means 272, timing setting means 273, A / D converter 274, identification means 275, Determination means 276.

  The BPF 271 receives a radio wave via the antenna 21 and extracts a signal having the frequency of the wakeup signal WK from the received radio wave. Then, the BPF 271 outputs the extracted signal to the envelope detection means 272.

  The envelope detection means 272 detects the envelope of the signal received from the BPF 271 and outputs a signal consisting of an envelope (hereinafter referred to as “envelope signal EVL”) to the timing setting means 273.

  The timing setting means 273 receives the envelope signal EVL from the envelope detection means 272, sets the sampling timing for sampling the envelope signal EVL based on the received envelope signal EVL, and sets the sampling timing. The line signal EVL is output to the A / D converter 274.

  The A / D converter 274 receives the envelope signal EVL with the sampling timing set from the timing setting means 273, samples the envelope signal EVL with the sampling timing set in the received envelope signal EVL, and obtains a sampling value Get. The A / D converter 274 converts each sampling value from an analog signal to a digital signal, and outputs the converted digital signal to the identification unit 275 and the determination unit 276.

  Based on the digital signal received from the A / D converter 274, the identification unit 275 identifies whether the received radio wave is a wake-up signal WK or a wireless LAN signal by a method described later, and the identification result is obtained. It outputs to the determination means 276.

  Determination unit 276 determines whether or not the identification information represented by the digital signal received from A / D converter 274 matches the identification information of access point 20. Then, the determination unit 276 receives a signal indicating that the received radio wave is identified as the wake-up signal WK by the identification unit 275 from the identification unit 275 and represents the signal by the digital signal received from the A / D converter 274. When it is determined that the identification information to be matched with the identification information of the access point 20, a wakeup instruction signal Wu_comd is generated, and the generated wakeup instruction signal Wu_comd is output to the power supply 25.

  FIG. 6 is a conceptual diagram for explaining a method of generating wakeup signal WK. Referring to FIG. 6, when ID generation means 121 of wakeup signal transmitter 12 receives instruction signal Wup from wireless LAN card 13, it calculates the hash value of the MAC address of access point 20, and the calculated hash value Is set to wake-up ID = 1001 (see (a)).

  Then, the arithmetic means 122 receives the wakeup ID = 1001 from the ID generation means 121, Manchester encodes the received wakeup ID = 1001, and obtains a bit string “0101101001”. That is, the arithmetic means 122 converts “1” to “01”, converts “0” to “10”, and obtains the bit string “0101101001” from the wakeup ID = 1001 (see (b)).

  The on / off control means 123 receives the bit string “0101101001” from the calculation means 122, controls on / off based on the received bit string “0101101001”, and generates an on / off control signal SS (see (c)). ).

  On the other hand, according to the chirp spread spectrum CSS (see (d)), the frequency spreading means 124 spreads the frequency to a higher frequency side than the center frequency and a lower frequency side than the center frequency, with 2.412 GHz as the center frequency, CYS (see (e)) is generated.

  Multiplier 125 receives on / off control signal SS from on / off control means 123 and carrier signal CYS from frequency spreading means 124. Then, multiplier 125 multiplies carrier signal CYS by on / off control signal SS to generate wakeup signal WK (see (f)).

  In the wake-up signal WK, the period T1 is a period corresponding to two consecutive “0” in the on / off control signal SS.

  The transmission means 127 uses a PIFS (point) in the communication scheme according to IEEE802.11 in which the off period T1 of the wakeup signal WK corresponding to the off period (a period corresponding to two consecutive “0” s) in the on / off control signal SS. The transmission rate is determined so as to be shorter than the coordination function frame space), and the wakeup signal WK is transmitted using the determined transmission rate.

  This PIFS is the shortest time among the times for determining whether or not a channel is in an idle state in a communication scheme based on IEEE 802.11. Therefore, in the embodiment of the present invention, the transmission means 127 transmits the off period T1 of the wake-up signal WK corresponding to the off period (a period corresponding to two consecutive “0”) in the on / off control signal SS. Is determined such that the transmission rate is shorter than the shortest idle determination time in the communication scheme according to IEEE 802.11, and the wakeup signal WK is transmitted using the determined transmission rate.

  Due to this feature, while the transmission unit 127 is transmitting the wakeup signal WK, no other terminal device or access point transmits a wireless LAN signal, and the wakeup signal WK is accurately transmitted to the access point 20. Can be transmitted.

  As described above, Manchester encoding of the wakeup ID = 10011 converts “1” of the wakeup ID = 1001 to “01” and “0” of the wakeup ID = 1001 to “10”. It corresponds to doing.

  As a result, in the bit string “0101101001” obtained by Manchester encoding of the wakeup ID = 11011, the maximum value of the number of consecutive “0” is “2”.

  Therefore, the off period T1 of the wake-up signal WK corresponding to the off period (period corresponding to two consecutive “0” s) in the on / off control signal SS is shorter than the shortest idle determination time in the communication scheme based on IEEE 802.11. If the transmission rate is determined so as to be shorter, it is possible to avoid a wireless LAN signal being transmitted during transmission of the wakeup signal WK.

  The reason why the carrier signal CYS is generated by spreading the frequency according to the chirp spread spectrum CSS is to set the spectrum density and bandwidth of the transmission wave to satisfy the radio communication regulation. As a result, the influence of the wakeup signal WK on other signals can be suppressed.

  FIG. 7 is a conceptual diagram of an envelope of received radio waves. Referring to FIG. 7, envelope detection means 272 of wakeup signal receiver 27 performs envelope detection on the signal from BPF 271 to obtain envelope signal EVL.

  And the timing setting means 273 sets sampling timing t1-t10 for sampling the envelope signal EVL to the envelope signal EVL. The A / D converter 274 samples the envelope signal EVL at the sampling timings t1 to t10, quantizes the sampled value, and converts the envelope signal EVL into a digital signal.

  FIG. 8 is a conceptual diagram of a wake-up signal and a signal by a wireless LAN. Referring to FIG. 8, the sampling value of envelope signal EVL of wakeup signal WK is represented by a value close to “0” and a value close to “1” (see (a)).

  On the other hand, the sampling value of the envelope signal EVL of the signal by the wireless LAN is represented by an arbitrary value, and there is not much time to turn off continuously.

  Therefore, the identification unit 275 identifies whether the received radio wave is a wake-up signal WK or a wireless LAN signal by the following method.

(Identification method 1)
The wakeup signal WK has a preamble / data configuration. The length of the preamble is N bits. N is a system parameter, for example, 5. The preamble is a known bit string and is Manchester encoded like data.

  Sampling values at sampling timings t1 to t10 shown in FIG. 7 are x (1) to x (10), respectively. And two adjacent sampling values x (1), x (2); x (3), x (4); x (5), x (6) in the sampling values x (1) to x (10); Let x (7), x (8); x (9), x (10) be x (2n-1), x (2n). n is an integer of 1 or more.

The discriminating means 275 substitutes the quantized values / x (2n-1) and / x (2n) obtained by quantizing the sampling values x (2n-1) and x (2n) into the following expression / x ( 2n-1) and / x (2n) are calculated as an exclusive OR y ₁ (n).

  Note that the notation / x represents the quantized value of the sampling value x, and “/” is the same as “^” arranged above x in Equation (1).

  When the received radio wave is composed of the wake-up signal WK, as is apparent from FIG. 7, one of the two quantized values / x (2n−1) and / x (2n) is “1”. The other is “0”.

Therefore, when the received radio wave is composed of the wake-up signal WK, the exclusive OR y ₁ (n) of / x (2n−1) and / x (2n) is always “1” unless there is thermal noise. become.

When the identification unit 275 calculates the exclusive OR y ₁ (n) for all the quantized values / x (2n−1) and the quantized values / x (2n), the calculated exclusive OR y ₁ ( The average value MCR is calculated by substituting n) into the following equation.

In the case illustrated in FIG. 7, five exclusive ORs y ₁ (n) are calculated, and N is “5”. Each of the five exclusive ORs y ₁ (n) is “1” as described above. Therefore, when the received radio wave is composed of the wake-up signal WK, the average value MCR is “1”.

  Therefore, the identification unit 275 identifies that the received radio wave is the wake-up signal WK if the average value MCR is equal to or greater than the threshold value c (0 <c <1, for example, 0.5), and the average value MCR is the threshold value c. If it is smaller than that, the received radio wave is identified as a wireless LAN signal.

(Identification method 2)
Identification means 275 receives sampling values x (2n-1) and x (2n) from A / D converter 274, and substitutes the received sampling values x (2n-1) and x (2n) into the following equation. To calculate y ₂ (n).

Then, the identification unit _275, the absolute value of _{y 2 (n) | y 2} (n) | is calculated and the calculated absolute value _| y 2 (n) _| a quantized, the quantized value _{/ y} 2 (n )

Then, the identification unit 275 calculates the average value SMCR by substituting the quantized value / y ₂ (n) into the following equation.

As shown in FIG. 7, one of the two sampling values x (2n−1) and x (2n) is a value close to “1”, and the other is a value close to “0”. y ₂ (n) is a value close to “1” or “−1”.

Then, quantized values _{/ y} 2 _(n), the absolute value of _{y 2 (n) | y 2} (n) | Since the is obtained by quantizing, unless thermal noise is not, always becomes "1" . As a result, when the received radio wave is the wake-up signal WK, the average value SMCR is also “1”.

  Therefore, the identification means 275 identifies that the received radio wave is the wake-up signal WK if the average value SMCR is greater than or equal to the threshold c, and if the average value SMCR is less than the threshold c, the received radio wave is a signal from the wireless LAN. Identify it.

(Identification method 3)
The identification unit 275 calculates y ₂ (n) using Expression (3), and calculates the average value MSMCR by substituting the calculated y ₂ (n) into the following expression.

As described above, y ₂ (n) has a value close to “1” or “−1”. Then, the average value MSMCR _the absolute value of _y 2 (n) _| is the average value | y 2 (n). As a result, when the received radio wave is the wake-up signal WK, the average value MSMCR is a value close to “1”.

  Accordingly, the identification unit 275 identifies that the received radio wave is the wake-up signal WK if the average value MSMCR is greater than or equal to the threshold value c, and if the average value MSMCR is less than the threshold value c, the received radio wave is a signal from the wireless LAN. Identify it.

  Identification means 275 identifies whether the received radio wave is a wake-up signal WK or a wireless LAN signal using any one of identification methods 1 to 3 described above. When using the identification method 1, the identification unit 275 receives the digital value (= quantized value / x (2n−1), / x (2n)) from the A / D converter 274, and identifies the identification method 2 or the identification method. When the method 3 is used, the sampling values x (2n−1) and x (2n) are received from the A / D converter 274.

  The determination unit 276 decodes the identification information using one of the following two methods.

(Decoding method 1)
The determination unit 276 performs hard decoding and calculates bits from the quantized values / x (2n-1) and / x (2n). That is, the determination unit 276 receives the quantized values / x (2n−1) and / x (2n) from the A / D converter 274. Then, when the quantized value / x (2n−1) is “0” and the quantized value / x (2n) is “1”, the determination unit 276 determines the nth bit of the wakeup ID. Is set to “1”. In addition, the determination unit 276 determines that the nth bit of the wakeup ID when the quantized value / x (2n−1) is “1” and the quantized value / x (2n) is “0”. Is set to “0”. Further, the determination means 276 determines a reception error in other cases.

(Decoding method 2)
The determination unit 276 performs soft decoding and calculates bits from y ₂ (n) in Equation (3). That is, the determination unit 276 receives the sampling values x (2n−1) and x (2n) from the A / D converter 274. Then, the determination unit 276 calculates y ₂ (n) by substituting the sampling values x (2n−1) and x (2n) into Expression (3). Thereafter, if y ₂ (n)> 0, the determination unit 276 sets the nth bit of the wakeup ID to “1”. Further, if y ₂ (n) ≦ 0, the determination unit 276 sets the nth bit of the wakeup ID to “0”.

  FIG. 9 is a flowchart for explaining the operation in radio communication system 100 shown in FIG. In FIG. 9, the operation in the wireless communication system 100 will be described on the assumption that the access point 20 is in the sleep state.

  Referring to FIG. 9, when a series of operations is started, the wireless LAN card 13 of the terminal device 10 issues a transmission instruction Wup for the wakeup signal WK to the wakeup signal transmitter 12 (step S1).

  Then, the wakeup signal transmitter 12 of the terminal device 10 generates a wakeup ID by the above-described method, and encodes the generated wakeup ID with Manchester (step S2).

  Thereafter, the wakeup signal transmitter 12 of the terminal device 10 generates an on / off control signal SS based on a bit string obtained by Manchester-encoding the wakeup ID (step S3).

  Further, the wake-up signal transmitter 12 of the terminal device 10 performs frequency spreading control using the chirp spread spectrum CSS and generates a carrier signal CYS (step S4).

  Then, the wakeup signal transmitter 12 of the terminal device 10 generates the wakeup signal WK by multiplying the carrier signal CYS by the on / off control signal SS (step S5), and amplifies the wakeup signal WK (step S6). ).

  Then, the wake-up signal transmitter 12 of the terminal device 10 performs carrier sense on the channel (step S7), and determines whether or not the channel is in an idle state (step S8).

  When it is determined in step S8 that the channel is not in an idle state, the series of operations returns to step S7, and steps S7 and S8 are repeatedly executed.

  When it is determined in step S8 that the channel is in an idle state, the wakeup signal transmitter 12 of the terminal apparatus 10 determines that the wakeup signal WK has the shortest idle period in the wireless communication scheme (IEEE 802.11). Radio waves are transmitted through the antenna 11 at a transmission rate that is shorter than the determination time (for example, PIFS) (step S9).

  The wakeup signal receiver 27 of the access point 20 receives radio waves from the terminal device 10 via the antenna 21 (step S10), and applies BPF (step S11).

  Then, the wakeup signal receiver 27 of the access point 20 performs envelope detection of the received radio wave (step S12) and sets the sampling timing (step S13).

  Then, the wakeup signal receiver 27 of the access point 20 samples the received radio wave to detect the sampling values x (2n−1) and x (2n), and also samples the sampling values x (2n−1) and x (2n). ) Is quantized. That is, the wakeup signal receiver 27 of the access point 20 performs A / D conversion (step S14).

  Then, the wakeup signal receiver 27 of the access point 20 receives the sampling values x (2n−1), x (2n), or the sampling values x (2n−1), x (2n) and the quantized value / x (2n). -1) and / x (2n) are used to discriminate between the wake-up signal WK and the wireless LAN signal by the method described above (step S15).

  Further, the wakeup signal receiver 27 of the access point 20 determines whether the identification information (= wakeup ID) obtained by decoding the received radio wave coincides with the identification information of the access point 20 in parallel with step S15. Is determined (step S16).

  Then, the wakeup signal receiver 27 of the access point 20 determines whether or not the received radio wave is the wakeup signal WK and the identification information obtained by decoding the received radio wave matches the identification information of the access point 20. Is determined (step S17).

  In step S17, when it is determined that the received radio wave is the wake-up signal WK and the identification information obtained by decoding the received radio wave matches the identification information of the access point 20, the access point 20 receives the wake-up signal. The device 27 outputs a wakeup instruction signal Wu_comd to the power supply 25 (step S18), and the power supply 25 supplies power to the wireless LAN card 22, the CPU 23, and the network connection card 24 in accordance with the wakeup instruction signal Wu_comd. As a result, the access point 20 shifts from the sleep state to the activated state.

  In step S17, when it is determined that the received radio wave is not the wake-up signal WK, or the identification information obtained by decoding the received radio wave does not match the identification information of the access point 20, or after step S18, The series of operations ends.

  As described above, the terminal apparatus 10 generates a bit string “0101101001” in which the identification information (for example, 11001) of the access point 20 is Manchester encoded, and corresponds to the off period in which “0” is consecutive in the bit string “0101101001”. The radio wave is transmitted at a transmission rate in which the off period (= T1) of the wakeup signal WK is shorter than the shortest idle determination time (for example, PIFS) in the wireless communication system (IEEE802.11).

  As a result, the wireless LAN signal is not transmitted during transmission of the wakeup signal WK, and the wakeup signal WK is accurately transmitted to the access point 20. Further, the access point 20 accurately receives a radio wave composed of the wakeup signal WK and detects the wakeup signal WK transmitted from the terminal device 10.

  Therefore, erroneous detection of the wakeup signal can be suppressed.

  Further, the access point 20 identifies the wakeup signal WK and the signal from the wireless LAN based on the received radio wave, and detects the wakeup signal WK when the received radio wave is identified as the wakeup signal WK.

  Therefore, erroneous detection of the wakeup signal WK can be suppressed at the access point 20.

  Furthermore, the terminal apparatus 10 performs frequency spreading control using the chirp spread spectrum CSS to generate the carrier signal CYS, and transmits the wakeup signal WK to the access point 20 using the generated carrier signal CYS.

  Therefore, the spectral density and bandwidth of the transmission wave can satisfy the radio communication regulations.

  FIG. 10 is another configuration diagram of the wake-up signal receiver 27 shown in FIG. In the embodiment of the present invention, the wake-up signal receiver 27 shown in FIG. 4 may comprise the wake-up signal receiver 27A shown in FIG.

  Referring to FIG. 10, wakeup signal receiver 27A is obtained by replacing identification means 275 and determination means 276 of wakeup signal receiver 27 shown in FIG. 5 with identification means 275A and determination means 276A, respectively. The configuration of is the same as that of the wake-up signal receiver 27.

  In the wake-up signal receiver 27A, the BPF 271, the envelope detection means 272, the timing setting means 273, the A / D converter 274, and the identification means 275A are always supplied with power from the power supply 26, and the determination means 276A is Until the wakeup signal WK is detected, power is not supplied from the power source 26. That is, the BPF 271, the envelope detection unit 272, the timing setting unit 273, the A / D converter 274, and the identification unit 275A are always in the activated state, and the determination unit 276A is in the sleep state until the wakeup signal WK is detected. It is.

  The identification unit 275A receives the quantized values / x (2n-1) and / x (2n) or the sampling values x (2n-1) and x (2n) of the received radio wave from the A / D converter 274.

  Then, identification means 275A identifies whether the received radio wave is a wake-up signal WK or a wireless LAN signal using any one of identification methods 1 to 3 described above.

  When identifying means 275A identifies that the received radio wave is wake-up signal WK, identification means 275A generates activation signal PON for activating determination means 276A, and outputs the generated activation signal PON to power supply 26. Then, the power supply 26 supplies power to the determination unit 276A in response to the activation signal PON from the identification unit 275A.

  As a result, the determination unit 276A is activated, and the received radio wave sampling values x (2n-1) and x (2n) received from the A / D converter 274 or the received radio wave quantization value / x (2n-1). , / X (2n), the identification information included in the received radio wave is decoded, and it is determined whether or not the decoded identification information matches the identification information of the access point 20.

  Note that, when the determination unit 276A decodes the identification information based on the quantized values / x (2n-1) and / x (2n), the decoding method 1 described above is used and the received radio wave sampling value x (2n− 1) When decoding the identification information based on x (2n), the above-described decoding method 2 is used.

  Determination unit 276A outputs wake-up instruction signal Wu_comd to power supply 25 when it is determined that the identification information included in the received radio wave matches the identification information of access point 20. As a result, the power supply 25 supplies power to the wireless LAN card 22, the CPU 23, and the network connection card 24, and the access point 20 shifts from the sleep state to the activated state.

  FIG. 11 is another flowchart for explaining the operation of radio communication system 100 shown in FIG.

  The flowchart shown in FIG. 11 is obtained by replacing steps S15 to S18 of the flowchart shown in FIG. 9 with steps S19 to S23, and the other parts are the same as the flowchart shown in FIG.

  Further, the flowchart shown in FIG. 11 is a flowchart for explaining the operation of the wireless communication system 100 when the access point 20 includes the wake-up signal receiver 27A shown in FIG.

  Referring to FIG. 11, when a series of operations is started, the above-described steps S1 to S14 are sequentially executed.

  Then, after step S14, in the wakeup signal receiver 27A of the access point 20, the identification unit 275A uses the identification method 1 to the identification method 3 described above to generate the wakeup signal WK and the signal from the wireless LAN. Identify (step S19).

  Then, the identification unit 275A determines whether or not the received radio wave is the wakeup signal WK (step S20).

  When it is determined in step S20 that the received radio wave is the wake-up signal WK, the identification unit 275A generates the activation signal PON and outputs it to the power source 26. The power source 26 determines the power according to the activation signal PON. It supplies to the means 276A (step S21).

  Then, the determination unit 276A is activated by the power from the power supply 26, and determines whether or not the identification information obtained by decoding the received radio wave matches the identification information of the access point 20 (step S22).

  When it is determined in step S22 that the identification information obtained by decoding the received radio wave matches the identification information of the access point 20, the determination unit 276A outputs the wakeup instruction signal Wu_comd to the power supply 25 (step S23). The power supply 25 supplies power to the wireless LAN card 22, the CPU 23, and the network connection card 24 in response to the wake-up instruction signal Wu_comd. As a result, the access point 20 shifts from the sleep state to the activated state.

  Then, when it is determined in step S20 that the received radio wave is not the wake-up signal WK, or in step S22, it is determined that the identification information obtained by decoding the received radio wave does not match the identification information of the access point 20. Or after step S23, the series of operations ends.

  As described above, in the wakeup signal receiver 27A, the determination unit 276A is activated when the identification unit 275A identifies the received radio wave as the wakeup signal WK.

  Therefore, the power consumption can be further reduced as compared with the case where the access point 20 includes the wakeup signal receiver 27.

  In addition, the same effect as when the access point 20 includes the wake-up signal receiver 27 can be obtained.

  FIG. 12 is a schematic diagram of another wireless communication system according to the embodiment of the present invention. The wireless communication system according to the embodiment of the present invention may be wireless communication system 200 shown in FIG.

  Referring to FIG. 12, the wireless communication system 200 includes a terminal device 10 and access points (AP) 201 to 210.

  Access points (AP) 201-210 are arranged in a mesh. The access point (AP) 201 is connected to the gateway 220 via the wired cable 230. The gateway 220 is connected to the network 30 via a wired cable 240.

  The access point (AP) 201 communicates between the gateway 220 and the access point (AP) 202 (or access point (AP) 206), and wirelessly communicates with a terminal device (not shown) under the control. Communicate. Each access point (AP) grasps an adjacent access point (AP) that is the shortest route to the gateway by exchanging control packets for routing.

  Each of the access points (AP) 202 to 210 performs communication with two adjacent access points and also performs wireless communication with a terminal device (not shown) under its control.

  For example, the terminal device 10 is arranged under the access point (AP) 204. The terminal device 10 performs wireless communication with the access point (AP) 204 according to the flowchart shown in FIG. 9 or FIG.

  FIG. 13 is a block diagram of the access point 201 shown in FIG. Referring to FIG. 13, an access point (AP) 201 is obtained by adding a wake-up signal transmitter 12 to the access point 20 described above.

  In the access point (AP) 201, the CPU 23 sleeps when the access point (AP) 202, 206 does not receive a packet from the access point (AP) 202, 206 adjacent to the access point (AP) 201 for a certain period of time. It is determined that it is in a state.

  Further, the CPU 23 of the access point (AP) 201 is woken up by a terminal device under the access point (AP) 201 or one of the adjacent access points (AP) 202 (or access point (AP) 206).

  The access point (AP) 202 has the same configuration as the access point (AP) 201 shown in FIG. When the CPU 23 of the access point (AP) 202 is woken up by a terminal device subordinate to the access point (AP) 202 or one of the adjacent access points (AP) 203, the CPU 23 of the access point (AP) 202 An instruction signal to wake up access point (AP) 201 is output to wake up signal transmitter 12.

  The wakeup signal transmitter 12 of the access point (AP) 202 generates and transmits a wakeup signal WK by the method described above in response to an instruction signal from the CPU 23.

  Each of the access points (AP) 203 to 210 shown in FIG. 12 has the same configuration as that of the access point (AP) 201 shown in FIG.

  Referring to FIG. 12 again, when all of the access points (AP) 201 to 210 are in the sleep state, the terminal device 10 wakes up by the method described above when starting communication via the network 30. A signal WK is generated and transmitted to the access point (AP) 204.

  The access point (AP) 204 receives the wake-up signal WK from the terminal device 10 and shifts from the sleep state to the activated state by the same method as the access point 20 described above.

  Thereafter, the access point (AP) 204 generates a wake-up signal WK by the same method as the terminal device 10 and transmits it to the access point (AP) 203.

  The access point (AP) 203 receives the wake-up signal WK from the access point (AP) 204, and shifts from the sleep state to the activated state by the same method as the access point 20 described above.

  Subsequently, the access point (AP) 203 generates a wake-up signal WK by the same method as the terminal device 10 and transmits it to the access point (AP) 202.

  The access point (AP) 202 receives the wake-up signal WK from the access point (AP) 203, and shifts from the sleep state to the activated state by the same method as the access point 20 described above.

  Then, the access point (AP) 202 generates a wakeup signal WK by the same method as the terminal device 10 and transmits it to the access point (AP) 201.

  The access point (AP) 201 receives the wake-up signal WK from the access point (AP) 202, and shifts from the sleep state to the activated state by the same method as the access point 20 described above.

  As a result, the access points (AP) 201 to 204 that have been in the sleep state shift to the activated state.

  Therefore, the terminal device 10 can communicate via the access points (AP) 201 to 204, the gateway 220, and the network 30.

  The terminal devices arranged under the access points (AP) 202, 203, 205 to 210 other than the access point (AP) 204 are also connected from the access point to which the terminal device belongs to the access point (AP) 201 by the method described above. All access points existing on the path can be shifted from the sleep state to the activated state, and communication can be performed via the access point, the gateway 220, and the network 30 that have been shifted to the activated state.

  As described above, in the wireless communication system 200 in which the access points (AP) 201 to 210 are arranged in a mesh shape, even when the access points (AP) 201 to 210 are in the sleep state, the access points (AP) 201 to 210 are connected. The terminal device arranged under the control terminal wakes up the access point to which the terminal device belongs, and the wake-up access point sequentially wakes up the access points existing in the direction of the gateway 220 to communicate via the network 30. It can be performed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a terminal device, a wireless device that performs wireless communication with the terminal device, and a wireless communication system including them.

  10 terminal device, 11, 21 antenna, 12 wake-up signal transmitter, 13, 22 wireless LAN card, 14 CPU / display unit, 15, 25, 26 power supply, 20, 201-210 access point, 23 CPU, 24 network connection Card, 27, 27A wake-up signal receiver, 30 network, 40, 230, 240 wired cable, 100, 200 wireless communication system, 121 ID generating means, 122 computing means, 123 on / off control means, 124 frequency spreading means, 125 multiplier, 126 amplifying means, 127 transmitting means, 220 gateway, 271 BPF, 272 envelope detection means, 273 timing setting means, 274 A / D converter, 275, 275A identification means, 276, 276A determination means.

Claims (11)

An antenna used to transmit and receive wireless communication signals;
In response to a request for wireless communication, a calculation unit that Manchester-encodes identification information of a wireless device to be woken up;
A signal for generating an on / off control signal using the Manchester-encoded identification information and multiplying the generated on / off control signal by a carrier signal having a frequency used for the wireless communication to generate a wake-up signal Generating means;
Transmitting means for performing carrier sense on a channel having a frequency used for the wireless communication and transmitting the wake-up signal using the antenna when the channel is in an idle state,
The transmission means transmits the wake-up signal at a transmission rate at which an off period of the wake-up signal corresponding to an off period in the on / off control signal is shorter than a shortest time for determining an idle state of the channel. A terminal device.   The signal generation means generates the carrier signal by spreading the frequency to a higher frequency side and a lower frequency side than the center frequency with respect to a center frequency in a frequency band used for the wireless communication, and generates the carrier signal. The terminal device according to claim 1, wherein the wakeup signal is generated by multiplying the on / off control signal. An antenna used to transmit and receive wireless communication signals;
Wireless communication means for transmitting and receiving the wireless communication signal to and from the terminal device using the antenna, and transitioning to a sleep state when wireless communication with the terminal device is not performed for a certain period;
Receiving means for receiving radio waves via the antenna on a channel having a frequency used for transmission and reception of the wireless communication signal;
Identification means for identifying whether the received radio wave received by the reception means is a wake-up signal generated by Manchester encoding of the wireless communication signal and first identification information for identifying the wireless device; ,
When the received radio wave is the wake-up signal, it is determined whether or not second identification information obtained by decoding the received radio wave matches the first identification information, and the second identification information And a determination unit that activates the wireless communication unit that has shifted to the sleep state when it matches the first identification information ,
In the wake-up signal, an off period of the wake-up signal corresponding to an off period in an on / off control signal generated using the Manchester-encoded first identification information determines an idle state of the channel. A wireless device that is transmitted from a terminal device at a transmission rate that is shorter than the shortest time to do . A computing means for performing computation and for shifting to the sleep state when the wireless communication means does not perform wireless communication for a certain period;
A network connection unit that connects the wireless device to a network, and the wireless communication unit shifts to the sleep state when wireless communication is not performed for a certain period of time;
The wireless device according to claim 3, wherein the determination unit further activates the calculation unit and the network connection unit that have shifted to the sleep state when the second identification information matches the first identification information.   The identification means detects an envelope of the received radio wave, detects the intensity of the envelope detected by the envelope detection at a plurality of timings, quantizes the detected intensity, and a plurality of quantized quantized values A process of calculating an exclusive OR of two adjacent quantized values is performed for all of the plurality of quantized values, and an average value of the exclusive OR is calculated for the plurality of quantized values. The wireless device according to claim 3 or 4, wherein when the calculated average value is equal to or greater than a threshold value, the received radio wave is identified as the wake-up signal.   The identification means detects an envelope of the received radio wave, detects an intensity of the envelope detected by the envelope detection at a plurality of timings, and −1 of one of two adjacent intensities among the detected intensities. And a process of quantizing the absolute value of the sum of the multiplication result obtained by multiplying the other two adjacent intensities by 1 and the multiplication result obtained by multiplying the other two adjacent intensities by 1 for all of the plurality of intensities. The radio apparatus according to claim 3 or 4, wherein an average value of quantized values is calculated, and the received radio wave is identified as the wake-up signal when the calculated average value is equal to or greater than a threshold value.   The identification means detects an envelope of the received radio wave, detects an intensity of the envelope detected by the envelope detection at a plurality of timings, and −1 of one of two adjacent intensities among the detected intensities. A process for calculating the absolute value of the sum of the multiplication result obtained by multiplying the other two adjacent intensities by 1 and the multiplication result obtained by multiplying the other two intensities by 1 is performed for all of the plurality of intensities, and the calculated plurality of absolute values The wireless device according to claim 3, wherein the received radio wave is identified as the wakeup signal when the calculated average value is equal to or greater than a threshold value.   The determination means determines that the second identification information matches the first identification information, and transitions to the sleep state when the received radio wave is identified as the wake-up signal by the identification means. The wireless device according to claim 3, wherein at least wireless communication means is activated.   The determination unit is activated when the identification unit identifies the received radio wave as the wake-up signal, and determines whether or not the second identification information matches the first identification information. The wireless device according to any one of claims 3 to 7, wherein when the second identification information matches the first identification information, at least a wireless communication unit that has shifted to the sleep state is activated. . A terminal device;
A wireless device that performs wireless communication with the terminal device;
The terminal device comprises the terminal device according to claim 1 or claim 2,
The said radio | wireless apparatus is a radio | wireless communications system which consists of a radio | wireless apparatus of any one of Claims 3-9. A terminal device;
A plurality of access points that are connected to a network and arranged in a mesh, and perform wireless communication with the terminal device;
The terminal device comprises the terminal device according to claim 1 or claim 2,
Each of the plurality of access points is
A wakeup signal transmitter is further included in addition to the configuration of the wireless device according to any one of claims 3 to 9 .
The wake-up signal transmitter includes the calculation unit, the signal generation unit, and the transmission unit of the terminal device according to claim 1 or 2.
When the terminal device starts the wireless communication, the terminal device transmits the wake-up signal to one access point of the plurality of access points,
The one access point is activated in response to the wake-up signal from the terminal device,
Wherein one access point other than the access point is activated in response to the wake-up signal from the access point located in said one of said one access point side than the access point, or self, radio communications system.

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