JP6026910B2 - Wireless device and wireless communication system including the same - Google Patents

Description

  The present invention relates to a radio apparatus and a radio communication system including the same.

  2. Description of the Related Art Conventionally, a power-saving wireless system is known in which a wireless base station in a sleep state is activated and used only when necessary by transmitting a simple wireless signal from a terminal device (Non-Patent Documents 1 to 3).

Tetsuya Ito, Yoshihisa Kondo, Shiro Sakata, Zenji Ikenaga, Hiroyuki Shikata, “Overview of Radio-On-Demand Networks to reduce wasted power consumption,” IEICE 2011 General Conference B-6-132. Yoshihisa Kondo, Hiroyuki Shikata, Hana Yumoto, Toshiyasu Tanaka, Yuji Iwai, Hideo Tsutsui, Sadao Obana, “On-demand wake-up method of wireless LAN access point using wireless LAN signal,” IEICE Technical Report NS2010-185 (March 2011). Kosuke Namba, Hiroyuki Shikata, Yoshihisa Kondo, Yuka Humi, “A Study on ID Design for Radio-On-Demand Networks Using a Wake-up Receiver,” IEICE Technical Report NS2010-187 (March 2011 ).

  However, in a network configuration in which the same network identifier (ESSID: Extended Service Set Identifier) is assigned to a plurality of radio base stations, a plurality of radio base stations Start at the same time.

  In such a case, the density of radio base stations existing around the terminal device that transmits the wake-up signal is measured, and the wake-up probability that is the probability of wake-up using the measured density of the radio base stations is obtained. It is assumed that the number of radio base stations activated at the same time is suppressed by waking up the radio base station based on the obtained wake-up probability.

  However, in such a method, when the distribution of radio base stations existing around the terminal device that transmits the wake-up signal is non-uniform, the density information and the wake-up signal owned by each radio base station are used. There is a problem in that the actual density of the radio base stations existing around the terminal apparatus to be transmitted does not match, and the number of times of wakeup uselessly or the number of retransmissions of the wakeup signal increases.

  Also, in the prior art, since the radio base station is not woken up in consideration of the received signal strength of the wakeup signal, the radio base station existing at a desired position is woken up from the terminal device that transmits the wakeup signal. There is a problem that it is difficult to do.

  Therefore, the present invention has been made to solve such a problem, and its purpose is to suppress useless wakeup even when the distribution of wireless devices to be activated is non-uniform, and Another object of the present invention is to provide a wireless device that can wake up when it exists at a desired position from a wireless device that transmits a wakeup signal.

  Another object of the present invention is to prevent useless wakeup even when the distribution of wireless devices to be activated is non-uniform, and to provide a desired position from a wireless device that transmits a wakeup signal. It is to provide a wireless communication system that can wake up when it exists.

  According to the embodiment of the present invention, the wireless device includes a receiving unit, a detecting unit, a determining unit, a determining unit, an activation unit, and a communication unit. The receiving means receives a wake-up signal for starting up the wireless device in the sleep state from the wireless device as the transmission source. The detecting means detects the received signal strength when the receiving means receives the wake-up signal. The determination means is the number of times that the wireless device has transitioned from the sleep state to the activated state and the wireless device has established a wireless link with the transmission source wireless device out of the number of times the wireless device has transitioned from the sleep state to the activated state. The average value of the effective wake-up probability indicating the ratio of the number of effective wake-ups in the wireless device or the average value of the effective wake-up probability in the wireless device and other wireless devices existing around the wireless device, and The first activation probability determined based on the number of times that the wireless device has maintained the sleep state and the second activation probability determined based on the received signal strength are weighted and averaged to obtain the final activation probability. decide. The determination unit determines whether or not the wakeup signal received by the reception unit indicates that the wireless device is to be shifted from the sleep state to the activated state. The activation means generates an activation signal with a final activation probability when it is determined by the determination means that the wake-up signal indicates that the wireless device is to be shifted from the sleep state to the activation state. The communication means shifts from the sleep state to the activated state according to the activation signal generated by the activation means. Then, the determining means determines the first activation probability so that the probability value becomes small when the average value of the effective wake-up probabilities is equal to or less than the first threshold value, and the maintenance frequency is the second threshold value. When it is above, the first activation probability is determined so as to increase.

  The wireless communication system according to the embodiment of the present invention includes a plurality of wireless devices. Each of the plurality of wireless devices includes the wireless device according to any one of claims 1 to 7.

  In the wireless device according to the embodiment of the present invention, the first activation probability increases or decreases depending on the average value of the effective wake-up probability or the condition that the number of times the sleep state is maintained. The second activation probability is determined based on the received signal strength of the wakeup signal. As a result, the possibility that the final activation probabilities are the same in the plurality of wireless devices is reduced, and the possibility that the plurality of wireless devices are simultaneously woken up is reduced. Further, if the second activation probability is determined based on the received signal strength, the possibility that the wireless device present at the desired position will wake up increases.

  Therefore, even when the distribution of wireless devices to be activated is non-uniform, useless wake-up can be suppressed, and wireless devices existing at desired positions can be woken up.

1 is a schematic diagram of a radio communication system according to an embodiment of the present invention. It is a block diagram which shows the structure of the wireless base station shown in FIG. It is a block diagram of the terminal device shown in FIG. FIG. 3 is a functional block diagram of the signal generator shown in FIG. 2. It is a conceptual diagram of a log table. It is a figure which shows the example of correspondence table TBL1. It is a figure which shows the example of correspondence table TBL2. It is a figure which shows the example of correspondence table TBL3. It is a flowchart for demonstrating operation | movement of the wireless base station when it is a sleep state. Start is a diagram showing the relationship between the probability _{Z RI} and the received signal strength RSSI_WKE. Start is a diagram showing the relationship between the average value Pavr probability Z _EW and effective wakeup probability. It is a figure which shows the relationship between f (N _SLP ) in Formula (3), and the maintenance frequency N _SLP . It is a figure which shows the structure of a sensor network.

  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 radio communication system 100 according to an embodiment of the present invention includes radio base stations 1 to n (n is an integer of 2 or more) and a terminal device 10.

  Each of the wireless base stations 1 to n has an activation state in which wireless communication (= data transmission / reception) is performed with the terminal device 10 and a sleep state in which wireless communication (= data transmission / reception) cannot be performed with the terminal device 10. . In the embodiment of the present invention, among the radio base stations 1 to n, a plurality of radio base stations are assigned the same ESSID, and among the radio base stations 1 to n, another plurality of radio base stations are assigned. The station may be assigned another same ESSID. That is, the radio base stations 1 to n may include at least two groups of a plurality of radio base stations to which the same network identifier (ESSID) is assigned.

  The radio base stations 1 to n periodically transition from the sleep state to the activated state, and exchange log information, which is history information related to wakeup, with each other. The period is set, for example, for one day.

  Each of the radio base stations 1 to n exchanges log information with an adjacent radio base station every time a transition is made from the sleep state to the activated state. When a long time elapses, the probability that the timing for shifting to the activated state matches any one of the radio base stations is high, and the log information can be exchanged.

  Details of the log information will be described later.

  Each of the radio base stations 1 to n obtains the activation probability Z by a method to be described later when in the sleep state. Then, when each of the radio base stations 1 to n receives the wake-up signal WKE for activating the radio base station from the terminal device 10, the radio base stations 1 to n shift from the sleep state to the activated state based on the activation probability Z. After that, each of the radio base stations 1 to n periodically transmits a beacon frame Beacon (= management frame) for managing the terminal device 10 when the wireless base stations 1 to n are shifted to the activated state, and establishes a radio link with the terminal device 10. Establish. Then, each of the wireless base stations 1 to n performs wireless communication with the terminal device 10 in the 2.45 GHz band, for example.

  The terminal device 10 generates and broadcasts a wakeup signal WKE. And the terminal device 10 establishes a radio link with any one of the radio base stations 1 to n by a method described later, and performs radio communication in the 2.45 GHz band.

  FIG. 2 is a configuration diagram showing the configuration of the radio base station 1 shown in FIG. Referring to FIG. 2, radio base station 1 includes antennas 11 and 12, wakeup device 13, main device 14, and power supply 15.

  The antenna 11 is connected to the wakeup device 13. The antenna 12 is connected to the main device 14.

  The wake-up device 13 receives, for example, 100 μW of power from the power supply 15 and is driven by the received power. The wakeup device 13 receives and holds the ID of the radio base station 1 from the main device 14. When the wakeup device 13 receives the wakeup signal WKE from the terminal device 10 via the antenna 11 on the channel X, the wakeup device 13 detects the received signal strength RSSI_WKE when the wakeup signal WKE is received, and also wakes up the signal WKE. It is determined whether or not the wakeup ID included in the ID matches the ID of the radio base station 1. Further, the wakeup device 13 obtains the activation probability Z by a method described later. Then, when it is determined that the wakeup ID included in the wakeup signal WKE matches the ID of the radio base station 1, the wakeup device 13 generates a random number r, and the generated random number r is less than the activation probability Z. When the start signal is generated, the generated start signal is output to the main device 14.

  On the other hand, the wakeup device 13 discards the wakeup signal WKE when the wakeup ID does not match the ID of the radio base station 1 or when the random number r is greater than the activation probability Z. Then, the wakeup device 13 waits for reception of the wakeup signal WKE.

  Note that the wakeup device 13 has only a function of receiving a packet such as a wakeup signal WKE and does not have a function of transmitting a packet. Channel X is a fixed channel set to one frequency in the 2.45 GHz band.

  The main device 14 receives, for example, 7 W of power from the power supply 15 and is driven by the received power. Further, the main device 14 outputs the ID of the radio base station 1 to the wakeup device 13.

  When the main device 14 is in the sleep state and receives an activation signal from the wakeup device 13, the main device 14 shifts from the sleep state to the activation state. Then, the main device 14 generates a wake-up notification WN (Wake-up Notification) indicating that the radio base station 1 has been activated, and the generated wake-up notification WN is transmitted to the terminal device 10 via the antenna 12 on the channel X. Send to. After that, when the main apparatus 14 receives a wake-up notification response RWN (Reply to WN), which is a response to the wake-up notification WN, from the terminal apparatus 10 on the channel X via the antenna 12, the main apparatus 14 communicates with the terminal apparatus 10 on the channel Y. To establish a wireless link with the terminal device 10. Then, the main apparatus 14 outputs a link establishment signal LES indicating that a radio link has been established with the terminal apparatus 10 to the wakeup apparatus 13 and performs radio communication with the terminal apparatus 10 through the channel Y. The main device 14 communicates with other communication devices via a wired cable (not shown).

  Further, when the main device 14 is in the activated state and receives an activation signal from the wakeup device 13, the main device 14 generates an active notification AN (Active Notification) indicating that the radio base station 1 is activated. The active notification AN is transmitted to the terminal device 10 via the antenna 12 via the channel X. Then, the main device 14 performs IEEE 802.11 association with the terminal device 10 on the channel Y, and establishes a wireless link with the terminal device 10. Then, the main device 14 performs wireless communication with the terminal device 10 through the channel Y.

  Note that the main device 14 does not output the link establishment signal LES to the wakeup device 13 when receiving the activation signal when in the activated state and establishing a radio link with the terminal device 10.

  The power supply 15 supplies 100 μW of power to the wakeup device 13 and supplies 7 W of power to the main device 14.

  The wakeup device 13 includes a wakeup signal receiver 131, a wakeup determiner 132, and a signal generator 133. The main device 14 includes a wireless communication module 141, a wired communication module 142, and a host system 143.

  The wakeup signal receiver 131 has only a function of receiving a packet and does not have a function of transmitting a packet.

  The wake-up signal receiver 131 has a channel X. Then, wakeup signal receiver 131 waits for wakeup signal WKE on channel X.

  When the wakeup signal receiver 131 receives the wakeup signal WKE via the antenna 11, the wakeup signal receiver 131 detects the received signal strength RSSI_WKE when the wakeup signal WKE is received, and the signal generator 133 detects the detected received signal strength RSSI_WKE. Output to. The wakeup signal receiver 131 demodulates the received wakeup signal WKE and outputs the demodulated wakeup signal WKE to the wakeup determiner 132.

  The wakeup determination unit 132 receives the ID of the radio base station 1 from the host system 143 and holds it. Wakeup determiner 132 receives demodulated wakeup signal WKE from wakeup signal receiver 131. Then, wakeup determination unit 132 extracts a wakeup ID included in the received wakeup signal WKE.

  Then, the wakeup determination unit 132 determines whether or not the wakeup ID matches the ID of the radio base station 1. When it is determined that the wake-up ID matches the ID of the radio base station 1, the wake-up determination unit 132 generates a match signal MTCH and outputs it to the signal generator 133. The wakeup determination unit 132 outputs nothing to the signal generator 133 when determining that the wakeup ID does not match the ID of the radio base station 1A. In this case, the wakeup determination unit 132 discards the wakeup signal WKE.

The signal generator 133 holds the coefficients w _EW and w _RI in advance. The signal generator 133 receives the received signal strength RSSI_WKE from the wakeup signal receiver 131, receives the match signal MTCH from the wakeup determiner 132, and receives the link establishment signal LES from the host system 143.

Then, when the signal generator 133 receives the coincidence signal MTCH, the signal generator 133 obtains the activation probability Z _RI by a method described later based on the received signal strength RSSI_WKE, and in a certain period Trenew (for example, one day) by a method described later. The activation probability Z _EW is obtained based on the average value of the effective wake-up probabilities. Then, the signal generator 133 calculates the activation probability Z by substituting the activation probabilities Z _RI and Z _EW and the coefficients w _EW and w _RI into the following equation.

In equation (1), each of the coefficients w _EW and w _RI is composed of an arbitrary value between 0 and 1.0 so as to satisfy w _EW + w _RI = 1.

  The effective wakeup probability and the average value of the effective wakeup probability will be described later.

  After calculating the activation probability Z, the signal generator 133 generates a random number r by a built-in random number generator and compares the generated random number r with the activation probability Z.

  Then, when the random number r is equal to or less than the activation probability Z, the signal generator 133 generates an activation signal and outputs the generated activation signal to the host system 143.

On the other hand, when the random number r is larger than the activation probability Z, the signal generator 133 does not generate an activation signal. In this case, since the main device 14 maintains the sleep state without shifting to the activated state, the signal generator 133 counts the number of maintenance times N _SLP that the main device 14 has maintained the sleep state within a certain period _TWD . The counted number of maintenance times N _SLP is held. The fixed period _TWD is set to 1 minute, for example.

  When the main device 14 is in the activated state, the signal generator 133 receives from the host system 143 log information received by the main device 14 from the radio base stations existing around the radio base station 1, and the received log information. Hold.

  When receiving the command signal COM1 from the host system 143, the wireless communication module 141 shifts from the activated state to the sleep state, and when receiving the command signal COM2 from the host system 143, the wireless communication module 141 shifts from the sleep state to the activated state. This sleep state is a state in which the wireless communication module 141 has stopped operating.

  When the wireless communication module 141 shifts from the sleep state to the activated state and receives the wake-up notification WN from the host system 143, the wireless communication module 141 modulates the received wake-up notification WN according to the wireless LAN communication method and uses the channel X as a terminal. Transmit to device 10.

  Thereafter, the wireless communication module 141 receives the wakeup notification response RWN from the terminal device 10 via the antenna 12 via the channel X, and outputs the received wakeup notification response RWN to the host system 143. When the wireless communication module 141 receives an instruction to associate with the terminal device 10 from the host system 143, the wireless communication module 141 performs IEEE 802.11 association with the terminal device 10 on the channel Y, and Establish a wireless link between them. Then, the wireless communication module 141 generates a packet including data received from the host system 143 and transmits the generated packet to the terminal device 10 through the channel Y. The channel Y is determined before the main apparatus 14 shifts to the sleep state, and is composed of a frequency channel having one frequency arbitrarily determined in the 2.45 GHz band. Since channel Y is determined to be one arbitrary frequency channel in the 2.45 GHz band, it may be the same as channel X or may be different from channel X.

  Further, when receiving the active notification AN from the host system 143, the wireless communication module 141 modulates the received active notification AN according to the wireless LAN communication method and transmits it to the terminal device 10 through the channel X.

  When the wireless communication module 141 receives an instruction to associate with the terminal device 10 from the host system 143, the wireless communication module 141 performs IEEE 802.11 association with the terminal device 10 through the channel Y, and Establish a wireless link between them. Then, the wireless communication module 141 generates a packet including data received from the host system 143 and transmits the generated packet to the terminal device 10 through the channel Y.

  Further, when the wireless communication module 141 receives a packet from the terminal device 10 on the channel Y via the antenna 12, the wireless communication module 141 extracts data from the received packet and outputs the data to the host system 143.

  Further, the radio communication module 141 receives a beacon frame Beacon from other radio base stations existing around the radio base station 1, and detects a received signal strength RSSI_Beacon when the beacon frame Beacon is received. Then, the wireless communication module 141 outputs the beacon frame Beacon and the received signal strength RSSI_Beacon to the host system 143.

  The wired communication module 142 receives data from another communication device via a wired cable (not shown), and outputs the received data to the host system 143.

  Further, the wired communication module 142 receives data from the host system 143 and transmits the received data to another communication device via a wired cable (not shown).

  Further, when the wired communication module 142 receives the command signal COM1 from the host system 143, the wired communication module 142 shifts from the activated state to the sleep state, and upon receiving the command signal COM2 from the host system 143, the wired communication module 142 shifts from the sleep state to the activated state. This sleep state is a state in which the wired communication module 142 has stopped operating.

  The host system 143 holds the ID of the radio base station 1 in advance, and outputs the held ID of the radio base station 1 to the wake-up determination unit 132 when it is in an activated state.

  Further, when the wireless communication module 141 establishes a wireless link with the terminal device 10 in the activated state, the host system 143 outputs a link establishment signal LES to the signal generator 133.

  Further, when the host system 143 receives the received signal strength RSSI_Beacon and the beacon frame Beacon from the wireless communication module 141 in the activated state, the host system 143 extracts the log information LOG in the other wireless base stations from the beacon frame Beacon, and extracts it. The log information LOG and the received signal strength RSSI_Beacon are output to the signal generator 133.

  Furthermore, the host system 143 holds the channel Y that was used to transmit and receive data to and from the terminal device 10 before shifting to the sleep state.

  Further, when the host system 143 receives an activation signal from the signal generator 133 while in the sleep state, the host system 143 shifts from the sleep state to the activation state. Then, the host system 143 generates a command signal COM2 and outputs it to the wireless communication module 141 and the wired communication module 142. Thereafter, the host system 143 generates a wakeup notification WN including the channel Y and the address of the wireless base station 1 and outputs the generated wakeup notification WN to the wireless communication module 141.

  When the host system 143 does not receive the wakeup notification response RWN from the wireless communication module 141 for a certain period after outputting the wakeup notification WN to the wireless communication module 141, the host system 143 receives the command signal COM1 from the wireless communication module 141 and the wired communication module 142. And then transitions from the activated state to the sleep state.

  On the other hand, if the host system 143 receives the wakeup notification response RWN from the wireless communication module 141 within a certain period after outputting the wakeup notification WN to the wireless communication module 141, the terminal device that has transmitted the wakeup notification response RWN. 10 is output to the wireless communication module 141.

  Further, when the host system 143 is in the activated state and receives the activation signal from the signal generator 133, the host system 143 generates an active notification AN including the channel Y and the address of the radio base station 1, and the generated active notification AN Is output to the wireless communication module 141. Then, the host system 143 outputs an instruction to perform association with the terminal device 10 to the wireless communication module 141.

  Further, when receiving data from the wireless communication module 141, the host system 143 outputs the received data to the wired communication module 142.

  Further, when receiving data from the wired communication module 142, the host system 143 outputs the received data to the wireless communication module 141.

  Further, the host system 143 manages terminal devices that exist within the communication range of the radio base station 1.

  Note that each of the radio base stations 2 to n illustrated in FIG. 1 has the same configuration as the radio base station 1 illustrated in FIG. 2.

  FIG. 3 is a configuration diagram of the terminal device 10 shown in FIG. With reference to FIG. 3, the terminal device 10 includes an antenna 21, a wireless communication module 22, and a host system 23.

  In the wireless communication module 22, a channel X for broadcasting the wakeup signal WKE is set in advance.

  The wireless communication module 22 receives the wake-up signal WKE from the host system 23, modulates the received wake-up signal WKE by an on-off keying modulation method, and transmits the modulated wake-up signal WKE via the antenna 21 via the channel X. Broadcast.

  This on / off keying modulation scheme is a modulation scheme with a transmission rate of several tens of kbps to several hundreds of kbps, and the transmission rate is lower than the modulation scheme used in a normal wireless LAN. The reason why the wakeup signal WKE is modulated by the modulation method having a low transmission rate in this way is to enable the wakeup signal WKE to be demodulated by the wakeup device 13 that operates at a very low power of 100 μW.

  After broadcasting the wake-up signal WKE, the wireless communication module 22 receives a wake-up notification WN from the connection-destination wireless base station CN (= any of the wireless base stations 1 to n) via the antenna 21 on the channel X. The received wakeup notification WN is output to the host system 23.

  Further, when the wireless communication module 22 receives the wakeup notification response RWN from the host system 23, the wireless communication module 22 modulates the received wakeup notification response RWN by the modulation method of the wireless LAN, and the modulated wakeup notification response RWN is transmitted to the channel X. Is transmitted to the radio base station CN via the antenna 21. After that, when receiving a channel Y for transmitting / receiving data from / to the radio base station CN from the host system 23, the radio communication module 22 receives a beacon frame Beacon from the radio base station CN via the antenna 21 on the channel Y. To do. Then, the wireless communication module 22 performs an IEEE 802.11 association with the wireless base station CN on the channel Y according to an instruction from the host system 23, and establishes a wireless link with the wireless base station CN.

  Further, the radio communication module 22 receives the active notification AN from the radio base station CN via the antenna 21 on the channel X, and outputs the received active notification AN to the host system 23. When the wireless communication module 22 receives the channel Y from the host system 23, the wireless communication module 22 associates the wireless base station CN with the wireless base station CN through the channel Y according to the instruction from the host system 23, and communicates with the wireless base station CN. Establish a wireless link between them.

  When the wireless communication module 22 establishes a wireless link with the wireless base station CN, the wireless communication module 22 performs wireless communication with the wireless base station CN through the channel Y. More specifically, the wireless communication module 22 receives a packet from the wireless base station CN via the antenna 21 via the channel Y, demodulates the received packet, extracts data, and extracts the extracted data from the host system 23. Output to. Further, the wireless communication module 22 receives data from the host system 23, generates a packet including the received data, modulates the generated packet by a modulation method using a wireless LAN, and transmits the modulated packet to the channel Y via an antenna. 21 to the radio base station CN.

  The host system 23 includes a wakeup signal generator 231. When the wakeup signal generator 231 receives the command signal COM3 and ESSID (or BSSID) from the host system 23, the wakeup signal generator 231 generates a wakeup ID including any one of ESSID, BSSID, and their hash values, and the generated wakeup A wakeup signal WKE including the ID is generated. The wakeup ID is information indicating a radio base station that is activated by the terminal device 10.

  Then, the wakeup signal generator 231 outputs the generated wakeup signal WKE to the wireless communication module 22.

  The host system 23 receives the beacon frame Beacon received by the wireless communication module 22 via the antenna 21 from the wireless communication module 22. Then, the host system 23 extracts and manages the ESSID or BSSID included in the received beacon frame Beacon, and manages the radio base station CN to which the terminal device 10 belongs based on the ESSID or BSSID.

  Further, when the host system 23 does not receive the beacon frame Beacon from the radio base station CN, the host system 23 determines that the radio base station CN is in a sleep state, and sends the command signal COM3 and ESSID (or BSSID) to the wakeup signal generator 231. Output.

  Further, when the host system 23 receives the wake-up notification WN from the wireless communication module 22, the host system 23 extracts the channel Y from the wake-up notification WN and outputs the extracted channel Y to the wireless communication module 22. Then, the host system 23 generates a wakeup notification response RWN that is a response to the wakeup notification WN and outputs the wakeup notification response RWN to the wireless communication module 22. This wake-up notification response RWN includes the address of the radio base station CN and the address of the terminal device 10. Thereafter, the host system 23 outputs an instruction to perform association with the radio base station CN to the radio communication module 22.

  Further, when receiving the active notification AN from the wireless communication module 22, the host system 23 extracts the channel Y from the active notification AN and outputs the extracted channel Y to the wireless communication module 22. Then, the host system 23 outputs an instruction for associating with the radio base station CN to the radio communication module 22.

  Further, the host system 23 receives data from the wireless communication module 22, generates data, and outputs the data to the wireless communication module 22.

  FIG. 4 is a functional block diagram of the signal generator 133 shown in FIG. Referring to FIG. 4, signal generator 133 includes control means 1331 and storage means 1332.

  The control means 1331 receives the received signal strength RSSI_WKE from the wakeup signal receiver 131, receives the coincidence signal MTCH from the wakeup determiner 132, and receives the received signal strength RSSI_Beacon, log information LOG, and link establishment signal LES from the host system 143. .

When receiving the received signal strength RSSI_WKE, the control unit 1331 reads the correspondence table TBL1 indicating the correspondence between the received signal strength and the activation probability Z _RI from the storage unit 1332 and refers to the received correspondence table TBL1. value corresponding to the received signal strength RSSI_WKE detects the to determine the detected value as a starting probability _{Z RI.}

Further, the control unit 1331 counts the number N _{DRV of} outputting the activation signal DRV to the host system 143 and the number N _{LES of} receiving the link establishment signal LES from the host system 143.

In the embodiment of the present invention, the concept of an effective wake-up count EW, an invalid wake-up count IW, and an effective wake-up probability P _EW is introduced.

  The effective wake-up count EW is defined as the number of times that the main apparatus 14 has transitioned from the sleep state to the activated state and the main apparatus 14 has established a radio link with the terminal apparatus 10.

  The invalid wakeup count IW is defined as the number of times that the main device 14 has shifted from the sleep state to the activated state, but the main device 14 has not established a wireless link with the terminal device 10.

Further, the effective wakeup probability P _EW is defined as (effective wakeup count) / (valid wakeup count + invalid wakeup count) = EW / (IW + EW) = N _LES / N _DRV .

Since the link establishment signal LES is output to the signal generator 133 after the main device 14 shifts from the sleep state to the activated state and the main device 14 establishes a wireless link with the terminal device 10, the number of times N _LES is It is equal to the effective wakeup number EW.

Therefore, when the control unit 1331 counts the number N _LES , the control unit 1331 sets the counted number N _LES as the effective wake-up number EW.

The invalid wakeup count IW is the number of times that the main device 14 has not established a wireless link with the terminal device 10 among the number of times that the main device 14 has shifted from the sleep state to the activated state, and has output the activation signal DRV. The number of times N _DRV is equal to the number of times that the main device 14 has shifted from the sleep state to the activated state. Therefore, when the number of times N _DRV is counted, the control unit 1331 subtracts the number of effective wakeup times EW from the number of times N _DRV. The number of times IW is obtained.

Furthermore, the control unit 1331, based on the effective wake-up times EW and invalid wakeup times IW, to calculate the effective wake-up probability _{P EW.}

Note that the control unit 1331 obtains the effective wake-up count EW, the invalid wake-up count IW, and the effective wake-up probability P _EW within a predetermined period Trenew.

The log information LOG includes the effective wake-up count EW, the invalid wake-up count IW and the effective wake-up probability P _EW in the radio base station 1, and the effective wake-up count EW in other radio base stations existing around the radio base station 1. , An invalid wake-up count IW and an effective wake-up probability P _EW .

  When receiving the received signal strength RSSI_Beacon and the log information LOG, the control unit 1331 reads a correspondence diagram RL indicating the correspondence between the known received signal strength and the distance from the storage unit 1332, and based on the read correspondence diagram RL, A distance L corresponding to the received signal strength RSSI_Beacon is obtained.

Then, the control unit 1331 stores the number of other radio base stations, the distance L, the effective wakeup number EW, the invalid wakeup number IW, and the effective wakeup probability P _EW in association with each other and stored in the storage unit 1332. Store in the log table TBL _LOG .

In addition, when the control unit 1331 obtains the effective wake-up count EW, the invalid wake-up count IW, and the valid wake-up probability P _EW in the radio base station 1, the number of the radio base station 1, the valid wake-up count EW, and the invalid wake-up The number of times IW and the effective wake-up probability P _EW are associated with each other and stored in the log table TBL _LOG .

Each time the control means 1331 receives the received signal strength RSSI_Beacon and log information LOG from the host system 143, the number, distance L, effective wakeup count EW, invalid wakeup count IW, and effective wakeup of other radio base stations to update the log table _{TBL lOG} to store the probability _{P EW} in the log table _{TBL lOG.} Further, the control means 1331 obtains the number of the radio base station 1, the number of valid wakeups EW, the number of invalid wakeups every time the valid wakeup number EW, invalid wakeup number IW and valid wakeup probability _PEW are obtained in the radio base station 1. stores up the number of times IW and an effective wake-up probability _{P EW} in the log table _{TBL lOG} to update the log table _{TBL lOG.}

The control unit 1331 reads all effective wake-up probabilities P _EW stored in the log table TBL _LOG when a certain period of time has elapsed, and based on all the read effective wake-up probabilities P _EW. The average value Pavr of _EW is obtained.

When the control unit 1331 calculates the average value Pavr, the control unit 1331 reads out the correspondence table TBL2 indicating the correspondence between the average value of the effective wake-up probabilities P _EW and the activation probability Z _EW from the storage unit 1332, and the read correspondence table TBL2 , A value corresponding to the obtained average value Pavr is detected, and the detected value is determined as the activation probability Z _EW .

When obtaining the activation probabilities Z _RI and Z _EW , the control means 1331 substitutes the coefficients w _RI and w _EW and the activation probabilities Z _RI and Z _EW into the equation (1) to obtain the activation probability Z. That is, the control means 1331 calculates the activation probability Z by weighted average of the activation probabilities Z _RI and Z _EW . Then, the control means 1331 generates a random number r and determines whether or not the generated random number r is equal to or less than the activation probability Z.

When the control unit 1331 determines that the random number r is equal to or less than the activation probability Z, the control unit 1331 generates the activation signal DRV and outputs the activation signal DRV to the host system 143 to increase the number N _DRV by “1”.

On the other hand, when the control unit 1331 determines that the random number r is larger than the activation probability Z, the control unit 1331 does not generate the activation signal DRV, and increases the maintenance count N _SLP that the main device 14 has maintained the sleep state by “1”. .

The control means 1331 holds in advance a threshold value Pth of the average value of the effective wake-up probabilities P _EW and a threshold value Nth_SLP of the number of maintenance times N _SLP that the main device 14 has maintained in the sleep state. The threshold value Pth is set to 80 to 90%, for example. The threshold value Nth_SLP is set to 5 times, for example.

When the average value Pavr of the effective wake-up probabilities P _EW is equal to or less than the threshold value Pth, the control unit 1331 reads the correspondence table TBL2 from the storage unit 1332 and refers to the read correspondence table TBL2, and the value is The activation probability Z _EW is updated so as to decrease.

In addition, when the maintenance count N _SLP is equal to or greater than the threshold value Nth_SLP, the control unit 1331 reads the correspondence table TBL3 indicating the correspondence relationship between the maintenance count N _SLP and the activation probability Z _EW from the storage unit 1332 and reads the correspondence Referring to table TBL3, activation probability Z _EW is updated so that the value increases.

Then, the control means 1331 obtains the activation probability Z using the updated activation probabilities Z _RI and Z _EW .

The storage unit 1332 stores the correspondence tables TBL1, TBL2, TBL3, the correspondence diagram RL, and the log table TBL _LOG .

FIG. 5 is a conceptual diagram of the log table TBL _LOG . Referring to FIG. 5, the log table TBL _LOG includes a radio base station (AP) number, a distance, an effective wake-up count EW, an invalid wake-up count IW, and an effective wake-up probability P _EW .

The radio base station (AP) number, distance, effective wake-up count EW, invalid wake-up count IW, and effective wake-up probability P _EW are associated with each other.

The radio base station number AP0 indicates the number of the radio base station that creates the log table TBL _LOG . The radio base station numbers AP1 to AP3 indicate the numbers of radio base stations other than the radio base station that creates the log table TBL _LOG .

The distance indicates the distance between the radio base station that creates the log table TBL _LOG and another radio base station. Accordingly, no specific numerical value is stored in the distance corresponding to the number AP0 of the radio base station that creates the log table TBL _LOG .

Each of the radio base stations 1 to n creates the log table TBL _LOG shown in FIG. 5 and stores it in the storage unit 1332 and updates the stored log table TBL _LOG .

FIG. 6 is a diagram illustrating an example of the correspondence table TBL1. Referring to FIG. 6, the correspondence table TBL1-1 includes a received signal strength RSSI_WKE, the activation probability _{Z RI.}

The received signal strength RSSI_WKE and the activation probability Z _RI are associated with each other. When the received signal strength RSSI_WKE is 0 ≦ RSSI_WKE ≦ 10, the activation probability Z _RI is 0.1, and when the received signal strength RSSI_WKE is 10 <RSSI_WKE ≦ 20, the activation probability Z _RI is 0.2. When the received signal strength RSSI_WKE is 20 <RSSI_WKE ≦ 30, the activation probability Z _RI is 0.3, and when the received signal strength RSSI_WKE is 30 <RSSI_WKE ≦ 40, the activation probability Z _RI is 0. 4 and when the received signal strength RSSI_WKE is 40 <RSSI_WKE ≦ 50, the activation probability Z _RI is 0.5, and when the received signal strength RSSI_WKE is 50 <RSSI_WKE ≦ 60, the activation probability Z _RI is 0.6, and the received signal strength RSSI_WKE is 60 <RSSI_WKE. If it is 70, start probability _{Z RI} is 0.7, when the received signal strength RSSI_WKE is 70 <RSSI_WKE ≦ 80, start probability _{Z RI} is 0.8, the received signal strength RSSI_WKE 80 < When RSSI_WKE ≦ 90, the activation probability Z _RI is 0.9, and when the received signal strength RSSI_WKE is 90 <RSSI_WKE, the activation probability Z _RI is 1.0.

Thus, activation probability _{Z RI,} for example, the larger the received signal strength RSSI_WKE, increases, the smaller the received signal strength RSSI_WKE, is determined to be smaller.

FIG. 7 is a diagram illustrating an example of the correspondence table TBL2. Referring to FIG. 7, correspondence table TBL2-1 includes an average value Pavr of effective wake-up probabilities and an activation probability Z _EW .

The average value Pavr of the effective wake-up probability and the activation probability Z _EW are associated with each other. When the average value Pavr of the effective wake-up probability is 0 ≦ Pavr ≦ 10, the activation probability Z _EW is Z _EW = Z _EW × 0.1, and the average value Pavr of the effective wake-up probability is 10 <Pavr ≦ 20 , The activation probability Z _EW is Z _EW = Z _EW × 0.2, and when the average value Pavr of the effective wake-up probability is 20 <Pavr ≦ 30, the activation probability Z _EW is Z _EW = Z _{When EW} × 0.3 and the average value Pavr of the effective wakeup probability is 30 <Pavr ≦ 40, the activation probability Z _EW is Z _EW = Z _EW × 0.4, and the average of the effective wakeup probability If the value Pavr is 40 <Pavr ≦ 50, start probability _{Z EW is} a _{Z EW =} Z EW × 0.5, the average value Pavr valid wakeup probability is 50 <Pavr If it is 60, start probability _{Z EW is} a _{Z EW =} Z EW × 0.6, when the average value Pavr valid wakeup probability is 60 <Pavr ≦ 70, start probability _{Z EW is Z EW} = When Z _EW × 0.7 and the average value Pavr of the effective wake-up probability is 70 <Pavr ≦ 80, the activation probability Z _EW is Z _EW = Z _EW × 0.8, and the effective wake-up probability When the average value Pavr is 80 <Pavr ≦ 90, the activation probability Z _EW is Z _EW = Z _EW × 0.9, and when the average value Pavr of the effective wake-up probability is 90 <Pavr ≦ 100, the activation The probability Z _EW is Z _EW = Z _EW × 1.0.

Note that the initial value of the activation probability Z _EW is set to 1.0.

Thus, the activation probability Z _EW is determined so as to decrease stepwise as the average value Pavr of the effective wake-up probability decreases, for example.

FIG. 8 is a diagram illustrating an example of the correspondence table TBL3. Referring to FIG. 8, correspondence table TBL3-1 includes the number of maintenance times N _SLP and the activation probability Z _EW .

The number of maintenance times N _SLP and the activation probability Z _EW are associated with each other. When the maintenance count N _SLP is 0 ≦ N _SLP ≦ 2, the activation probability Z _EW is Z _EW = Z _EW , and when the maintenance frequency N _SLP is 3 ≦ N _SLP ≦ 4, the activation probability Z _EW is When Z _EW = Z _EW × 1.2 and the number of maintenance times N _SLP is 5 ≦ N _SLP ≦ 6, the activation probability Z _EW is Z _EW = Z _EW × 1.4, and the number of maintenance times N _SLP is When 7 ≦ N _SLP ≦ 8, the activation probability Z _EW is Z _EW = Z _EW × 1.6, and when the maintenance number N _SLP is 9 ≦ N _SLP ≦ 10, the activation probability Z _EW is When Z _EW = Z _EW × 1.8 and the number of maintenance times N _SLP is 11 ≦ N _SLP , the activation probability Z _EW is Z _EW = Z _EW × 2.0.

_{Incidentally,} when the result of the _{Z EW} × _{1.2~Z EW} × 2.0 is greater than 1.0, a new start probability _{Z EW} is set to 1.0. Further, the initial value of the activation probability Z _EW is set to a value (see FIG. 7) determined in correspondence with the average value Pavr of the effective wake-up probability P _EW .

Thus, the activation probability Z _EW is determined to increase stepwise as the maintenance count N _SLP increases when the maintenance count N _SLP is equal to or greater than the threshold value Nth_SLP (5 times).

In the correspondence table TBL3-1, the activation probability Z _EW is increased stepwise with respect to the maintenance frequency N _SLP . However, in the embodiment of the present invention, the activation probability Z _EW is suddenly increased to “1. The start probability Z _EW may be increased by an arbitrary method as the number of maintenance times N _SLP increases.

  FIG. 9 is a flowchart for explaining the operation of the radio base stations 1 to n when in the sleep state.

  Referring to FIG. 9, when a series of operations is started, wakeup devices 13 of radio base stations 1 to n correctly receive wakeup signal WKE (step S1) and receive wakeup signal WKE. The received signal strength RSSI_WKE is detected.

  Then, the wakeup device 13 demodulates the wakeup signal WKE to detect the wakeup ID included in the wakeup signal WKE, and confirms that the detected wakeup ID matches the IDs of the radio base stations 1 to n. Detect.

In addition, the wakeup device 13 refers to the correspondence table TBL1, and detects the activation probability Z _RI corresponding to the detected received signal strength RSSI_WKE (step S2). The wakeup device 13 then updates the activation probability Z using the activation probability Z _RI by substituting the detected activation probability Z _RI into the equation (1) to calculate the activation probability Z (step S3). .

When step S3 is executed for the first time, an initial value (= 1.0) is used as the activation probability Z _EW . When step S3 is executed for the second time or later, it is updated in step S14 or step S18 described later. The activation probability Z _EW is used.

  After step S3, the wakeup device 13 generates a uniform random number ranging from 0 to 1, and stores the generated random number in r (step S4).

  Then, the wakeup device 13 determines whether or not the random number r is equal to or less than the activation probability Z (step S5).

  In step S5, when it is determined that the random number r is equal to or less than the activation probability Z, the wakeup device 13 generates the activation signal DRV and outputs it to the main device 14. Then, the main device 14 shifts from the sleep state to the activated state in response to the activation signal DRV from the wakeup device 13 (step S6).

  Subsequently, the wakeup device 13 determines whether or not the radio base stations 1 to n are connected to the terminal device (STA) by determining whether or not the link establishment signal LES is received from the main device 14 ( Step S7).

  In step S7, when it is determined that the radio base stations 1 to n are connected to the terminal device (STA), the wakeup device 13 calculates EW = EW + 1 (step S8).

  On the other hand, when it is determined in step S7 that the radio base stations 1 to n are not connected to the terminal device (STA), the wakeup device 13 calculates IW = IW + 1 (step S9).

  Then, after step S8 or step S9, the wake-up device 13 determines whether or not the update cycle (predetermined period Trenew) has elapsed (step S10).

  In step S10, when it is determined that the update cycle (predetermined period Trenew) has not elapsed, the series of operations proceeds to step S1.

On the other hand, when it is determined in step S10 that the update cycle (predetermined period Trenew) has elapsed, the wakeup device 13 is based on the valid wakeup count EW and the invalid wakeup count IW stored in the log table TBL _LOG. The effective wakeup probability P _EW is calculated (step S11).

Then, the wakeup device 13 refers to the log table TBL _LOG , reads the effective wakeup probability P _EW of another radio base station whose radius is within β (m), and reads the effective wakeup probability P _EW It calculates an average value Pavr valid wakeup probability _{P EW} using the _EW, the effective wake-up probability _{P EW} calculated in step S11 (step S12).

  Thereafter, the wakeup device 13 determines whether or not the average value Pavr is equal to or less than the threshold value Pth (step S13).

When it is determined in step S13 that the average value Pavr is less than or equal to the threshold value Pth, the wakeup device 13 refers to the correspondence table TBL2 to detect a value corresponding to the average value Pavr, and the detected value _Is set to a new activation probability Z _EW to update the activation probability Z _EW (step S14).

  When it is determined in step S13 that the average value Pavr is larger than the threshold value Pth, or after step S14, the wakeup device 13 resets the effective wakeup count EW and the invalid wakeup count IW ( Step S15). Thereafter, the series of operations proceeds to step S1.

On the other hand, when it is determined in step S5 that the random number r is greater than the activation probability Z, the wakeup device 13 counts the number of maintenance times N _SLP that has maintained the sleep state within a certain period _TWD (step S16).

Then, the wakeup device 13 determines whether or not the maintenance count N _SLP is equal to or greater than the threshold value Nth_SLP (step S17).

When it is determined in step S17 that the maintenance count N _SLP is equal to or greater than the threshold value Nth_SLP, the wakeup device 13 refers to the correspondence table TBL3, detects a value corresponding to the maintenance count N _SLP , and detects the detection. The _calculated value is set as a new activation probability Z _EW and the activation probability Z _EW is updated (step S18).

Then, when it is determined in step S17 that the maintenance count N _SLP is smaller than the threshold value Nth_SLP, or after step S18, the main device S19 maintains the sleep state (step S19).

  Thereafter, the series of operations proceeds to step S1.

  In this way, each of the radio base stations 1 to n repeatedly executes the above-described steps S1 to S19 to shift from the sleep state to the activated state or maintain the sleep state.

The calculation of the effective wake-up probability P _EW in step S11 is performed using the effective wake-up count EW and the invalid wake-up count IW stored in the log table TBL _LOG . Accordingly, the effective wakeup probability P _EW is calculated using the log information LOG.

The average value Pavr valid wakeup probability _{P EW} in step S12, the log table _{TBL LOG} stored in the enabled wakeup probability _{P EW} (radio base station to execute the flow chart shown in FIG. 9 and other than the radio base station It is calculated using the effective wakeup probability P _{EW of the} radio base station. Therefore, the average value Pavr of the effective wake-up probability P _EW is calculated using the log information LOG.

Then, by determining whether or not the average value Pavr is equal to or less than the threshold value Pth, it is determined whether or not to update the activation probability Z _EW so that the probability value becomes small (see steps S13 and S14).

Therefore, the flowchart shown in FIG. 9 is characterized by determining whether or not to update the activation probability Z _EW so as to reduce the probability value based on the log information.

Then, in step S14, activation probability Z _EW is updated so that the probability value is reduced in accordance with the valid wakeup probability P _EW, effective wakeup probability P _EW, the process proceeds to active state, and, indeed terminal The radio base station that is calculated using the number of times that the apparatus 10 and the radio link are probable (effective wake-up count EW) and that actually establishes the radio link with the terminal apparatus 10 is finally changed to one radio base station. Therefore, there is a high possibility that the effective wake-up probability P _EW will increase in one radio base station. Therefore, it is possible to reduce the possibility that a plurality of radio base stations simultaneously shift to the activated state.

The activation probability Z _EW is updated in step S14 when the average value Pavr of the effective wake-up probability P _EW is equal to or less than the threshold value Pth (80 to 90%) (see FIG. 7). Therefore, the activation probability Z _EW after the update is smaller than that before the update. As a result, in the wireless base station (any one of the wireless base stations 1 to n) that is continuously shifted from the sleep state to the activated state, the activation probability Z is decreased, and there is a possibility that the sleep state is shifted to the activated state. Lower.

If the wireless link cannot be established with the terminal device 10 even after the transition from the sleep state to the activated state, the invalid wakeup count IW increases (see step S9), and the effective wakeup probability P _EW Becomes smaller. As a result, there is a high possibility that the average value Pavr of the effective wake-up probability P _EW will be equal to or less than the threshold value Pth (80 to 90%), and the activation probability Z _EW is shown in the correspondence table TBL2-1 (see FIG. 7). Since it is updated so as to be smaller and the activation probability Z is smaller, the possibility of transition from the sleep state to the activation state is reduced.

On the other hand, even in a radio base station in which the activation probability Z _EW is small and the possibility of transition from the sleep state to the activation state is low, the activation is performed when the number N _SLP of maintaining the sleep state exceeds the threshold value Nth_SLP. The probability Z _EW is updated so as to increase with reference to the correspondence table TBL3-1 (see FIG. 8) (see step S18). As a result, the activation probability Z increases and the possibility of transition from the sleep state to the activation state increases.

  In this way, by controlling the wake-up of the radio base station according to the flowchart shown in FIG. 9, the activation probability Z in each of the radio base stations 1 to n is increased or decreased at any time, and a plurality of radio base stations can be The possibility of transition to the start state is reduced. Therefore, even when the distribution of the radio base stations 1 to n is non-uniform, useless wakeup can be suppressed.

Further, the activation probability Z _RI is updated with reference to the correspondence table TBL1-1 (see FIG. 6) based on the received signal strength RSSI_WKE when the wakeup signal WKE is received. _{The RI} increases as the distance between the radio base stations 1 to n and the terminal device 10 decreases. As a result, there is a high possibility that a radio base station (any one of the radio base stations 1 to n) existing near the terminal apparatus 10 can be woken up. Therefore, the radio base station (any one of the radio base stations 1 to n) existing at a desired position can be woken up from the terminal device 10 that transmits the wake-up signal.

Furthermore, when the radio base station 1~n has maintains the sleep state a certain number of times (threshold Nth_SLP) above, since updates the start probability _{Z EW} as larger (see step S18), and the updated boot probability _{Z EW} In this case, the activation probability Z increases and the possibility of wakeup increases.

  Therefore, the number of transmissions of the wakeup signal WKE can be reduced.

FIG. 10 is a diagram illustrating a relationship between the activation probability Z _RI and the received signal strength RSSI_WKE. Referring to FIG. 10, activation probability Z _RI increases linearly with increase in received signal strength RSSI_WKE (see (a) of FIG. 10).

Since the activation probability Z _RI increases linearly with respect to the increase in the received signal strength RSSI_WKE, the larger the received signal strength RSSI_WKE, the higher the activation probability Z. Even if the received signal strength RSSI_WKE is small, the activation probability Z is It won't be too low. As a result, when there is only a radio base station far from the terminal device 10, the number of retransmissions of the wakeup signal WKE can be suppressed.

In addition, the activation probability Z _RI increases nonlinearly with respect to the increase in the received signal strength RSSI_WKE (see FIG. 10B).

The activation probability Z _RI increases nonlinearly with respect to the increase in the received signal strength RSSI_WKE, so that the larger the received signal strength RSSI_WKE, the higher the activation probability Z becomes, and the activation of the radio base station with the smaller received signal strength RSSI_WKE. The probability Z can be brought close to “0”. As a result, the number of invalid wake-up times IW in the radio base station far from the terminal device 10 can be suppressed.

Further, the activation probability Z _RI increases as the received signal strength RSSI_WKE increases, reaches a maximum at any value of the received signal strength RSSI_WKE, and decreases as the received signal strength RSSI_WKE increases from an arbitrary value. (See (c) of FIG. 10).

By setting the relationship between the activation probability Z _RI and the received signal strength RSSI_WKE to the relationship shown in FIG. 10C, a node suitable for relay can be activated in the sensor network described later.

Furthermore, the activation probability Z _RI decreases linearly with increase in the received signal strength RSSI_WKE (see (d) of FIG. 10).

Since the activation probability Z _RI linearly decreases with respect to the increase in the received signal strength RSSI_WKE, a node far from the transmission source node can be activated in the sensor network described later, and the number of hops necessary for relaying can be reduced.

Note that the relationship between the activation probability Z _RI and the received signal strength RSSI_WKE shown in FIG. 6 corresponds to the case where the activation probability Z _RI is increased stepwise as the received signal strength RSSI_WKE increases.

In the wake-up device 13, the storage means 1332 of the signal generator 133 stores the relationship between the activation probability Z _RI and the received signal strength RSSI_WKE shown in any of (a) to (d) of FIG. 10 as the correspondence table TBL1. . Then, the control unit 1331 of the signal generator 133 reads from the storage unit 1332 the correspondence table TBL1 including the relationship between the activation probability Z _RI and the received signal strength RSSI_WKE shown in any of (a) to (d) of FIG. refers to the correspondence table TBL1 thus read out, to detect a value corresponding to the received signal strength RSSI_WKE, it may determine the detected value as a starting probability Z _RI.

Further, the storage means 1332 of the signal generator 133 stores at least one correspondence table TBL1 indicating the relationship between the activation probability Z _RI and the received signal strength RSSI_WKE shown in at least one of (a) to (d) of FIG. To do. Then, the control means 1331 of the signal generator 133 reads an arbitrary correspondence table TBL1 from at least one correspondence table TBL1 from the storage means 1332 and refers to the read correspondence table TBL1 to obtain a value corresponding to the received signal strength RSSI_WKE. May be detected, and the detected value may be determined as the activation probability _ZRI .

FIG. 11 is a diagram showing the relationship between the activation probability Z _EW and the average value Pavr of the effective wake-up probabilities.

Referring to FIG. 11, activation probability Z _EW decreases linearly as average value Pavr of effective wake-up probability P _EW decreases (see (a) of FIG. 11).

The activation probability Z _EW decreases linearly as the average value Pavr of the effective wake-up probability P _EW decreases, so that the higher the effective wake-up probability P _EW , the higher the wake-up probability, but the effective wake-up probability Even in a radio base station having a low P _EW , the wake-up probability is suppressed from decreasing too much. As a result, when a terminal device that can perform radio communication only with a radio base station having a low effective wake-up probability P _EW appears, the number of retransmissions of the wake-up signal WKE can be suppressed.

In addition, the activation probability Z _EW decreases nonlinearly as the average value Pavr of the effective wake-up probability P _EW decreases (see FIG. 11B).

By starting probability Z _EW decreases non-linearly with decreasing average Pavr valid wakeup probability P _EW, if valid wakeup probability P _EW is high, the wakeup probability is suddenly increased. As a result, quickly perform the reduction of the wakeup probability in the effective increase in the wakeup probability wakeup probability P _EW is in the high radio base station, and the effective wake-up probability P _EW is low radio base station.

In the wake-up device 13, the storage means 1332 of the signal generator 133 indicates the relationship between the activation probability Z _EW and the average value Pavr of the effective wake-up probability P _EW shown in any of (a) and (b) of FIG. It stores as correspondence table TBL2. Then, the control means 1331 of the signal generator 133 has a correspondence table TBL2 composed of the relationship between the activation probability Z _EW and the average value Pavr of the effective wake-up probability P _EW shown in any of (a) and (b) of FIG. May be read from the storage means 1332 and the activation probability Z _EW may be updated in step S14 shown in FIG. 9 with reference to the read correspondence table TBL2.

In the wake-up device 13, the storage means 1332 of the signal generator 133 stores the average value Pavr of the activation probability Z _EW and the effective wake-up probability P _EW shown in at least one of (a) and (b) of FIG. At least one correspondence table TBL2 indicating the relationship is stored. Then, the control means 1331 of the signal generator 133 reads an arbitrary correspondence table TBL2 from at least one correspondence table TBL2 from the storage means 1332 and starts up in step S14 shown in FIG. 9 with reference to the read correspondence table TBL2. The probability Z _EW may be updated.

The relationship between the average value Pavr activation probabilities _{Z EW} and effective wakeup probability _{P EW} shown in FIG. 7, reducing the activation probability _{Z EW} stepwise with decreasing average Pavr valid wakeup probability _{P EW} This is equivalent to

In the embodiment of the present invention, the control means 1331 of the signal generator 133 may update the activation probability Z _EW in step S14 shown in FIG. 9 according to the following equation.

In Expression (2), α is a constant smaller than 1.0, and Z _EW ^min is the minimum value of the activation probability Z _EW .

In equation (2), for example, if α = 0.5 and Z _EW ^min = 0.1, the probability Z _EW is 0.1 whenever the average value Pavr is determined to be equal to or less than the threshold value Pth. It will be halved in a range not less than.

In this case, the control means 1331 of the signal generator 133 holds α and Z _EW ^min in advance.

Thus, the control means 1331 of the signal generator 133 may update the activation probability Z _EW regardless of the average value Pavr.

Therefore, in step S14 shown in FIG. 9, generally, the activation probability Z _EW is updated so that the updated probability value is smaller than the updated probability value.

In the embodiment of the present invention, the control means 1331 of the signal generator 133 may update the activation probability Z _EW in step S18 shown in FIG. 9 according to the following equation.

FIG. 12 is a diagram illustrating the relationship between f (N _SLP ) and the number of maintenance times N _SLP in equation (3). Referring to FIG. 12, _{f (N SLP)} is linearly increased in the range of 1-2 with the maintenance number _{N SLP} is increased in the range of 1 to 10, maintaining the number of times _{N SLP} is 11 or more Then, a constant value (= 2) is obtained (see FIG. 12A).

As a result, the greater the number of maintenance times _{NSLP, the} higher the wake-up probability, but it is possible to suppress a sudden increase in the wake-up probability and suppress unnecessary activation of the radio base station.

Further, f (N _SLP ) increases nonlinearly in the range of 1 to 2 as the number of maintenance times N _SLP increases in the range of 1 to 10, and when the number of maintenance times N _SLP becomes 11 or more, a constant value ( = 2) (see FIG. 12B).

As a result, when the number of maintenance times N _SLP is large, the wakeup probability is rapidly increased, and the number of retransmissions of the wakeup signal WKE can be suppressed.

The storage unit 1332 of the signal generator 133 stores the relationship between f (N _SLP ) and the number of maintenance times N _SLP shown in any of (a) and (b) of FIG. Then, the control means 1331 of the signal generator 133 reads the relationship between f (N _SLP ) and the number of maintenance times N _SLP shown in any of (a) and (b) of FIG. Referring to the relationship between the f _{(N SLP)} and the sustain number _{N SLP,} detects the _{f (N SLP)} corresponding to maintain the number of times _{N SLP,} by substituting the detected _f a _{(N SLP)} in equation (3) To update the activation probability Z _EW .

In this case, as is clear from Equation (3), when the calculation result of Z _EW × f (N _SLP ) is greater than 1.0, the activation probability Z _EW is set to 1.0.

Note that the relationship between the activation probability Z _EW and the number of maintenance times N _SLP shown in FIG. 8 corresponds to the case where f (N _SLP ) is increased stepwise as the number of maintenance times N _SLP increases.

In the embodiment of the present invention, the control means 1331 of the signal generator 133 may update the activation probability Z _EW in step S18 shown in FIG. 9 according to the following equation.

  In the equation (4), γ is a constant and consists of a real number larger than 1.

For example, when γ is set to γ = 2, the control means 1331 of the signal generator 133 doubles the activation probability Z _EW every time it is determined that the maintenance count N _SLP is equal to or greater than the threshold value Nth_SLP.

In this case, as is apparent from the equation (4), when the calculation result of Z _EW × γ is larger than 1.0, the activation probability Z _EW is set to 1.0.

Thus, the control means 1331 of the signal generator 133 may update the activation probability Z _EW regardless of the number of maintenance times N _SLP .

Furthermore, in the embodiment of the present invention, the control means 1331 of the signal generator 133 sets the activation probability Z _EW to 1.0 each time it is determined that the maintenance count N _SLP is equal to or greater than the threshold value Nth_SLP. Thus, the activation probability Z _EW may be updated in step S18 shown in FIG.

As a result, the control means 1331 of the signal generator 133 updates the activation probability Z _EW regardless of the number of maintenance times N _SLP .

Therefore, in step S18 shown in FIG. 9, generally, the activation probability Z _EW is updated so that the updated probability value is larger than the updated probability value.

As described above, the activation probability Z _EW is updated by various methods in step S14 shown in FIG. 9, but generally, the control means 1331 of the signal generator 133 is used in step S14 shown in FIG. , activation probability Z _EW the updated as long as the method of reducing than start probability Z _EW before updating may update the start probability Z _EW using any method.

Further, as described above, the activation probability Z _EW is updated by various methods in step S18 shown in FIG. 9, but in general, the control means 1331 of the signal generator 133 performs the steps shown in FIG. in S18, activation probability Z _EW the updated as long as the method of increasing than start probability Z _EW before updating may update the start probability Z _EW using any method.

[Application Example 1]
FIG. 13 is a diagram illustrating a configuration of a sensor network. Referring to FIG. 13, the sensor network 200 includes nodes N-1 to N-16 and a sink S.

  The nodes N-1 to N-16 and the sink S are arranged in the wireless communication space. The nodes N-12, N-15, and N-16 are arranged at positions where data can be directly transmitted to the sink S, and the nodes N-1 to N-11, N-13, and N-14 are connected to the sink S. It is located at a position where data cannot be transmitted directly.

  The nodes N-1 to N-16 are normally in a sleep state, periodically shift to an activated state, and exchange the log information LOG described above with each other. In this case, the period is set to one day, for example.

  Then, each of the nodes N-1 to N-16 detects various data such as temperature, current value, humidity, and illuminance, and transmits the detected data to the sink S when transitioning to the activated state.

  The sink S collects data detected by the nodes N-1 to N-16 from the nodes N-1 to N-16.

  Each of the nodes N-1 to N-16 has both the function of the terminal device 10 described above and the functions of the radio base stations 1 to n.

  In the sensor network 200, a case will be described in which, among the nodes N-1 to N-16, the node N-1 shifts from the sleep state to the activated state, detects data, and transmits the detected data to the sink S.

In this case, each of the nodes N-1 to N-16 determines the activation probability _ZRI according to the relationship shown in FIG.

  Since the region REG is a transmission range of the wakeup signal WKE, the node N-1 cannot directly transmit the detected data to the sink S.

  Therefore, when detecting the data, the node N-1 generates a wakeup signal WKE by the same method as the terminal device 10 described above, and broadcasts the generated wakeup signal WKE.

  The nodes N-1 to N-3, N-5, and N-6 existing in the region REG receive the wakeup signal WKE from the node N-1. Then, any one of the nodes N-1 to N-3, N-5, and N-6 wakes up according to the flowchart shown in FIG. 9 in the same manner as the wireless base stations 1 to n described above.

Since each of the nodes N-1 to N-3, N-5, and N-6 determines the activation probability Z _RI according to the relationship shown in FIG. 10D, it exists at the position farthest from the node N-1. The activation probability Z _RI (resulting activation probability Z) in the node N-5 becomes the largest, and the node N-5 shifts from the sleep state to the activation state.

  Then, the node N-5 establishes a radio link with the node N-1 by the method described above. Then, the node N-1 transmits the detected data to the node N-5, and the node N-5 receives the data from the node N-1.

  After that, when transmitting the received data to the node arranged on the sink S side, the node N-5 generates a wakeup signal WKE by the same method as the terminal device 10 described above, and generates the generated wakeup signal WKE. Broadcast.

  Nodes existing around the node N-5 receive the wake-up signal WKE from the node N-5. Then, the node N-12 wakes up according to the flowchart shown in FIG.

  Then, the node N-12 establishes a radio link with the transmission source node N-5 by the method described above. Then, the node N-5 transmits data to the node N-12, and the node N-12 receives data from the node N-5.

  Thereafter, the node N-12 directly transmits the received data to the sink S, and the sink S receives data from the node N-12.

  As a result, the data detected by the node N-1 is transmitted to the sink S via the nodes N-5 and N-12.

  As described above, when the wireless communication system 100 is applied, the nodes N-5 and N-12 existing at the farthest position from the transmission source node or the node N-5 wake up, and the data detected by the node N-1 is detected. Therefore, data can be transmitted to the sink S using a route with the smallest number of relays.

Further, when each of the nodes N-1 to N-16 determines the activation probability Z _RI using the relationship shown in FIG. 10C, it exists at a certain distance from the source node or the node that relays data. Nodes that wake up sequentially relay data detected by the node N-1.

Therefore, by determining the activation probability Z _RI by various methods, the data detected by the node N-1 can be transmitted to the sink S via various routes.

[Application 2]
In the application example 1, the activation probability Z _RI is determined based only on the received signal strength. However, in the application example 2, each of the nodes N-1 to N-16 is activated based on the received signal strength and the metric value. Determine the Z _RI . In Application Example 2, each of the nodes N-1 to N-16 determines the activation probability Z _RI according to the relationship shown in FIG.

  This metric value indicates the degree to which each of the nodes N-1 to N-16 is close to the sink S. The metric value is larger as it is closer to the sink S.

  Accordingly, in the sensor network 200, the nodes N-1 to N-16 have a larger metric value as the distance from the sink S is shorter according to the distance from the sink S.

  Each of the nodes N-1 to N-16 shifts to an activated state at a constant cycle (for example, one day), and exchanges metric values held by itself with surrounding nodes. Then, each of the nodes N-1 to N-16 acquires the metric value of the surrounding node within the communication range of the node, and uses the maximum value of the metric value of the surrounding node and the metric value of the self, The probability A calculated by the value is obtained. For example, when the self metric value is 20 and the maximum value of the metric value of the neighboring nodes is 40, each of the nodes N-1 to N-16 calculates the probability A as 20/40 = 0.5. To do. That is, each of the nodes N-1 to N-16 determines the probability A such that the probability value increases as the metric value of the node N-1 to N-16 increases.

If the probability determined based on the received signal strength is B, each of the nodes N-1 to N-16 calculates the activation probability Z _RI by substituting the probabilities A and B into the following equations.

  In Expression (5), α is a real number that satisfies 0 <α <1.

As described above, each of the nodes N-1 to N-16 calculates the activation probability Z _RI by the weighted average of the probability A determined based on the metric value and the probability B determined based on the received signal strength. To do.

When the activation probability Z _RI is determined by the equation (5), the activation probability Z _RI (eventually the activation probability Z) becomes larger and wakes up as the node is farther from the transmission source and closer to the sink S. The possibility increases.

  The nodes N-1 to N-3, N-5, and N-6 existing in the region REG receive the wakeup signal WKE from the node N-1. Then, any one of the nodes N-1 to N-3, N-5, and N-6 wakes up according to the flowchart shown in FIG. 9 in the same manner as the wireless base stations 1 to n described above.

Since each of the nodes N-1 to N-3, N-5, and N-6 determines the activation probability Z _RI according to the relationship shown in FIG. 10D, it exists at a position farthest from the node N-1. In addition, the activation probability Z _RI (as a result of activation probability Z) in the node N-5 closest to the sink S becomes the largest, and the node N-5 shifts from the sleep state to the activation state.

  Then, the node N-5 establishes a radio link with the node N-1 by the method described above. Then, the node N-1 transmits the detected data to the node N-5, and the node N-5 receives the data from the node N-1.

  After that, when transmitting the received data to the node arranged on the sink S side, the node N-5 generates a wakeup signal WKE by the same method as the terminal device 10 described above, and generates the generated wakeup signal WKE. Broadcast.

  Nodes existing around the node N-5 receive the wake-up signal WKE from the node N-5. Then, the node N-13 wakes up according to the flowchart shown in FIG.

  Then, the node N-13 establishes a radio link with the transmission source node N-5 by the method described above. Then, the node N-5 transmits data to the node N-13, and the node N-13 receives data from the node N-5.

  Thereafter, the node N-13 directly transmits the received data to the sink S, and the sink S receives data from the node N-13.

  As a result, the data detected by the node N-1 is transmitted to the sink S via the nodes N-5 and N-13.

  As described above, when the wireless communication system 100 is applied, the nodes N-5 and N-13 that are located farthest from the transmission source node or the node N-5 and are closest to the sink S wake up, Since the data detected by the node N-1 is relayed, the data can be transmitted to the sink S using the route having the smallest number of relays and the shortest distance.

  In the application example 1, since the node farthest from the transmission source node relays data, the node existing in the direction from the transmission source node N-1 to the sink S does not always relay data.

  However, in the application example 2, since the node farthest from the transmission source node and closest to the sink S relays data, the node existing in the direction from the transmission source node N-1 to the sink S is the data. Is likely to relay. Therefore, data can be transmitted to the sink S using the route having the smallest number of relays and the shortest distance.

  Other explanations in the application example 2 are the same as those in the application example 1.

  Note that the wireless communication system 100 may be applied to a plurality of wireless devices constituting an ad hoc wireless network. In this case, each wireless device has both the function of the terminal device 10 and the functions of the wireless base stations 1 to n. Then, the transmission source wireless device generates and broadcasts the wakeup signal WKE, and the wireless devices existing around the transmission source wireless device receive the wakeup signal WKE and sleep according to the flowchart shown in FIG. Shifts to the activated state, establishes a wireless link with the transmission source wireless device, and performs wireless communication.

  In the above description, each of the radio base stations 1 to n periodically transitions to the activated state, and it has been described that the log information LOG is exchanged with other radio base stations existing around itself. In the embodiment, the radio base stations 1 to n preferably do not exchange the log information LOG.

In this case, each of the radio base stations 1 to n stores the effective wake-up number EW, the invalid wake-up number IW, and the effective wake-up probability P _EW within a predetermined period Trenew in the log table TBL _LOG . That is, each of the radio base stations 1 to n stores only the effective wakeup count EW, the invalid wakeup count IW, and the effective wakeup probability P _EW in the log table TBL _LOG .

Even when the log information LOG is not exchanged, the operation of the radio base station in the sleep state is executed according to the flowchart shown in FIG. In this case, in step S12, each of the radio base stations 1 to n reads the effective wake-up probability P _EW within a predetermined period Trenew from the log table TBL _LOG storing only its own log information LOG, and the read effective wake An average value Pavr of the up probability P _EW is calculated.

  As described above, when the log information LOG is not exchanged, it is possible to reduce the possibility that a plurality of radio base stations wake up simultaneously than when the log information LOG is exchanged.

  In addition, when the log information LOG is not exchanged, the radio base stations 1 to n exchange log information LOG by transitioning to a cyclic activation state, or a neighboring radio base station using a beacon frame Beacon or the like. There is no need to exchange information. On the other hand, in the method of waking up using the density of radio base stations, it is necessary for a plurality of radio base stations to exchange information with each other. Therefore, the power consumption in each of the radio base stations 1 to n can be reduced by not exchanging the log information LOG.

  As described above, the function of shifting from the sleep state to the activated state according to the flowchart shown in FIG. 9 is applicable not only to the wireless base station but also to a node in the sensor network 200 or a wireless device in an ad hoc wireless network. Therefore, in the embodiment of the present invention, the function of shifting from the sleep state to the activated state according to the flowchart shown in FIG. 9 is generally provided in the radio apparatus.

  As a result, the wireless device according to the embodiment of the present invention receives a wakeup signal for activating a wireless device in a sleep state from a transmission source wireless device, and the receiving unit receives the wakeup signal. Out of the number of times the wireless device has shifted from the sleep state to the activated state, and the wireless device has transitioned from the sleep state to the activated state, and the wireless device has The average value of the effective wake-up probability indicating the ratio of the number of times of effective wake-up that is the number of times a radio link has been established with the device, or the effective wake-up between the wireless device and other wireless devices existing around the wireless device It is determined based on the average value of the up probability and the number of times that the wireless device has maintained the sleep state. Determining means for determining a final activation probability by weighted averaging the first activation probability and the second activation probability determined based on the received signal strength, and the wake-up signal received by the receiving means A determination unit that determines whether or not to indicate that the device is to be shifted from the sleep state to the activated state, and a determination unit that determines that the wake-up signal indicates that the wireless device is to be shifted from the sleep state to the activated state. The activation means for generating the activation signal with the final activation probability, and the communication means for shifting from the sleep state to the activation state in accordance with the activation signal generated by the activation means, and the determining means is an average value of the effective wakeup probability When is less than or equal to the first threshold value, the first activation probability is determined so that the probability value is small, and the maintenance count is greater than or equal to the second threshold value It may be determined first activation probability to be larger.

  If the first activation probability increases or decreases depending on the condition that the average value or the number of maintenance times of the effective wakeup probability satisfies, the possibility that the final activation probability is the same in a plurality of wireless devices is reduced, and unnecessary wakeup is suppressed. This is because if the second activation probability is determined based on the received signal strength, the wireless device existing at a desired position can be woken up.

In the embodiment of the present invention, the activation probability Z _EW constitutes a “first activation probability”, the activation probability Z _RI constitutes a “second activation probability”, and the activation probability Z is “final activation probability”. Constitutes the "activation probability".

  In the embodiment of the present invention, the wakeup signal receiver 131 that detects the received signal strength RSSI_WKE constitutes “detection means”.

Furthermore, in embodiments of the present invention, activation probability _{Z RI,} and determines or updates the _{Z EW,} start probability _Z RI of the determined or updated _control means 1331 for determining the start probability Z with _{Z EW} is , “Deciding means”.

  Further, in the embodiment of the present invention, the wakeup determination unit 132 constitutes “determination means”.

  Furthermore, in the embodiment of the present invention, the control means 1331 that determines whether or not the random number r is equal to or less than the activation probability Z and generates the activation signal DRV when it is determined that the random number r is equal to or less than the activation probability Z is , “Starting means”.

  Further, in the embodiment of the present invention, the main device 14 constitutes “communication means”.

  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 radio base station that performs radio communication with the terminal device, and a radio communication system including these.

  1 to n wireless base station, 10 terminal device, 100 wireless communication system, 11, 12, 21 antenna, 13 wakeup device, 14 main device, 15 power supply, 22,141 wireless communication module, 23,143 host system, 131 wake Up signal receiver, 132 wakeup determination unit, 133 signal generator, 142 wired communication module, 231 wakeup signal generator, 1331 control means, 1332 storage means.

Claims (8)

Receiving means for receiving a wake-up signal for activating a wireless device in a sleep state from a transmitting wireless device;
Detecting means for detecting received signal strength when the receiving means receives the wake-up signal;
Of the number of times the wireless device has transitioned from the sleep state to the activated state, the number of times the wireless device has transitioned from the sleep state to the activated state and the wireless device has established a wireless link with the transmission source wireless device. The average value of the effective wake-up probability indicating the ratio of the number of effective wake-ups in the wireless device, or the average value of the effective wake-up probability in the wireless device and other wireless devices around the wireless device, and the The first activation probability determined based on the number of times that the wireless device has maintained the sleep state and the second activation probability determined based on the received signal strength are weighted and averaged to obtain the final activation. A determination means for determining the probability;
Determining means for determining whether or not the wake-up signal received by the receiving means indicates that the wireless device is to be shifted from the sleep state to the activated state;
An activation unit that generates an activation signal with the final activation probability when the determination unit determines that the wake-up signal indicates that the wireless device is to be shifted from the sleep state to the activation state;
Communication means for shifting from the sleep state to the activation state in response to the activation signal generated by the activation means,
The determining means determines the first activation probability so that the probability value becomes small when the average value of the effective wake-up probabilities is equal to or less than a first threshold value, and the maintenance count is a second value. A wireless device that determines the first activation probability so as to increase when it is equal to or greater than a threshold value.   The wireless device according to claim 1, wherein the determining unit determines the first activation probability based on an average value of effective wake-up probabilities in the wireless device or the number of maintenance times.   The determining means determines the first activation probability so that the updated probability value is smaller than the updated probability value when an average value of the effective wake-up probabilities is equal to or less than the first threshold value. The radio apparatus according to claim 2, wherein the final activation probability is determined by updating and performing a weighted average of the updated first activation probability and the second activation probability.   The determination means, when the activation means does not generate the activation signal based on the final activation probability, and the maintenance count is equal to or greater than the second threshold, the updated probability value is The first activation probability is updated so as to be larger than the probability value, and the final activation probability is determined by weighted averaging the updated first activation probability and the second activation probability. The wireless device according to claim 2 or claim 3.   The activation means generates a random number smaller than 1, and when the generated random number is less than or equal to the final activation probability, generates the activation signal and outputs the activation signal to the communication means, and the generated random number is the final activation The wireless device according to any one of claims 1 to 4, wherein the activation signal is not generated when the probability is larger than the probability.   The determination means determines the second activation probability based on the received signal strength so that a probability value becomes maximum in the wireless device existing at a desired distance from the transmission-source wireless device. The wireless device according to any one of claims 1 to 5.   The determination unit is configured to transmit the transmission signal based on the received signal strength and a metric value indicating a degree of proximity between the wireless device that relays data to a final transmission destination wireless device and the transmission destination wireless device. 6. The second activation probability is determined such that the probability value of the wireless device increases as the distance from the original wireless device becomes a desired distance and the metric value increases. The wireless device according to any one of the above.   A wireless communication system comprising a plurality of wireless devices each comprising the wireless device according to any one of claims 1 to 7.

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