JP5883968B2 - TERMINAL DEVICE, RADIO BASE STATION FOR RADIO COMMUNICATION WITH THE SAME AND RADIO COMMUNICATION SYSTEM INCLUDING THE SAME - Google Patents

Description

  The present invention relates to a terminal device, a radio base station that performs radio communication with the terminal device, and a radio communication system including these.

  2. Description of the Related Art Conventionally, there is known a power saving wireless system that activates and uses a wireless base station in a sleep state 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 General Conference 2011 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 There is a problem that they are started simultaneously and useless power is consumed. The same problem occurs when the wake-up signal is transmitted by broadcast or multicast.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to waste a plurality of radio base stations being activated by a single wakeup signal in a network having the same identifier or ESSID of the radio base station. It is providing the terminal device which can suppress.

  Another object of the present invention is to provide a radio base station capable of suppressing waste of activation of a plurality of radio base stations by a single wake-up signal in a network having the same radio base station identifier or ESSID. .

  Furthermore, another object of the present invention is to provide a radio communication system capable of suppressing waste of activation of a plurality of radio base stations by a single wake-up signal in a network having the same radio base station identifier or ESSID. .

According to the embodiment of the present invention, the terminal device includes signal generation means and transmission means. The signal generating means generates a wake-up signal for starting up the radio base station in the sleep state. The transmission means broadcasts the wake-up signal generated by the signal generation means, and a wake-up notification indicating that the radio base station has been activated or a radio base station is within the range of the maximum number of times of transmission of the wake-up signal. A wake-up signal is broadcast while increasing the transmission power until an active notification indicating that it is in an activated state is received from the radio base station.

  According to the embodiment of the present invention, the radio base station includes a receiving unit, a determining unit, an activation unit, and a communication unit. The receiving means receives from the terminal device a wake-up signal for starting the radio base station in the sleep state. The determining means determines whether or not the wake-up signal received by the receiving means indicates that the radio base station is activated. When the determination unit determines that the wake-up signal indicates that the radio base station is to be activated by the determination unit, the activation unit activates among a plurality of radio base stations existing around the terminal device in the communication range of the terminal device. An activation signal is generated with an activation probability indicating the ratio of radio base stations. The communication means is activated according to the activation signal generated by the activation means.

  Further, according to the embodiment of the present invention, the radio base station includes a receiving unit, a determining unit, an activation unit, and a communication unit. The receiving means receives from the terminal device a wakeup signal for activating the radio base station in the sleep state, and detects the received signal strength when the wakeup signal is received. The determining means determines whether or not the wake-up signal received by the receiving means indicates that the radio base station is activated. The activation means generates an activation signal when it is determined by the determination means that the wake-up signal indicates that the radio base station is activated. The communication means is activated according to the activation signal generated by the activation means. When the communication means is activated in response to the activation signal, the communication means transmits a wakeup advertisement including the received signal strength of the wakeup signal and state information indicating whether the wireless base station is in a sleep state or an active state. When broadcasting to other radio base stations other than the station and not receiving a wake-up advertisement from the other radio base station, a wake-up notification indicating that the radio base station is activated is transmitted to the terminal device, and the terminal device and the radio base station A first process for establishing a link or entering a sleep state is executed, and when a wake-up advertisement is received from another radio base station, the first process is executed based on the received wake-up advertisement. Alternatively, the second process of shifting to the sleep state without transmitting the wakeup notification to the terminal device is executed.

  Furthermore, according to the embodiment of the present invention, the radio communication system includes a terminal device and n (n is an integer of 2 or more) radio base stations. The terminal device includes the terminal device according to any one of claims 1 to 4. The n radio base stations include at least two groups of a plurality of radio base stations to which the same network identifier is assigned, and receive a wake-up signal for starting the radio base station in the sleep state from the terminal device. . Each of the n radio base stations includes the radio base station according to any one of claims 5 to 14.

  The terminal device according to the embodiment of the present invention broadcasts a wakeup signal while increasing transmission power. As a result, the wake-up signal gradually reaches further from the terminal device, and the plurality of radio base stations existing around the terminal device receive the wake-up signal in the order of proximity to the terminal device, and transition from the sleep state to the activated state. Transition.

  Accordingly, it is possible to suppress wasteful activation of a plurality of radio base stations at the same time.

  Also, the radio base station according to the embodiment of the present invention starts up according to the start probability when it is determined that the wake-up signal indicates to start up the own station. As a result, the number of radio base stations activated by the wake-up signal is suppressed compared to the case where the radio base station is activated immediately when it is determined that the wake-up signal indicates that the own station is activated.

  Accordingly, it is possible to suppress wasteful activation of a plurality of radio base stations at the same time.

  Furthermore, when the radio base station according to the embodiment of the present invention is activated by the wake-up signal, the radio base station exchanges wake-up advertisements with other radio base stations, and depending on whether or not the wake-up advertisement is received, Establish a wireless link or enter a sleep state. As a result, when activated by the wake-up signal, the number of radio base stations that finally maintain the activated state is smaller than when all the radio base stations establish radio links with the terminal devices.

  Accordingly, it is possible to suppress wasteful activation of a plurality of radio base stations at the same time.

  Furthermore, according to an embodiment of the present invention, a wireless communication system includes the terminal device and the wireless base station described above.

  Accordingly, it is possible to suppress wasteful activation of a plurality of radio base stations at the same time.

1 is a schematic diagram of a radio communication system according to an embodiment of the present invention. FIG. 2 is a configuration diagram of the radio base station shown in FIG. 1 in Embodiment 1. It is a block diagram of the terminal device shown in FIG. 3 is a conceptual diagram for explaining a method of starting a radio base station in Embodiment 1. FIG. It is a conceptual diagram of the table which shows the relationship between the frequency | count of transmission and transmission power. It is a flowchart for demonstrating operation | movement of a terminal device and a wireless base station when a wireless base station is a sleep state. It is a flowchart for demonstrating operation | movement of a terminal device and a wireless base station when a wireless base station is a starting state. It is a flowchart for demonstrating operation | movement of a terminal device. It is a flowchart for demonstrating operation | movement of a wireless base station. 6 is a configuration diagram of a radio base station in Embodiment 2. FIG. It is a conceptual diagram for demonstrating the method to estimate the number N of the radio base stations which exist around a terminal device. It is a flowchart for demonstrating the operation | movement in Embodiment 2 of a wireless base station. FIG. 10 is a configuration diagram of a radio base station in a third embodiment. It is a conceptual diagram of the table which shows the relationship between the frequency | count of reception of a wakeup signal, and constant (beta). FIG. 11 is a configuration diagram of a radio base station in a fourth embodiment. FIG. 10 is a configuration diagram of a radio base station in a fifth embodiment. 12 is a flowchart for explaining operations of a radio base station and a terminal device in the fifth embodiment. 10 is a flowchart for explaining an operation of a radio base station in the fifth embodiment.

  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 radio base stations 1 to n has an activation state in which wireless communication with the terminal device 10 is performed 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.

  When each of the radio base stations 1 to n receives a wake-up signal WKE for activating the radio base station from the terminal device 10 while in the sleep state, the radio base stations 1 to n shift from the sleep state to the activation state by a method described later. When each of the radio base stations 1 to n shifts to the activated state, the radio base stations 1 to n periodically transmit a beacon frame Beacon (= management frame) for managing the terminal device 10, and establish 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.

[Embodiment 1]
FIG. 2 is a configuration diagram of the radio base station 1 shown in FIG. 1 in the first embodiment. 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 ID included in the received wakeup signal WKE matches the ID of the radio base station 1. It is determined whether or not to do. When it is determined that the wake-up ID matches the ID of the radio base station 1, the wake-up device 13 generates an activation signal and outputs the generated activation signal to the main device 14.

  On the other hand, the wakeup device 13 discards the wakeup signal when the wakeup ID does not match the ID of the radio base station 1. Then, the wakeup device 13 waits for reception of a wakeup signal.

  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 device 14 performs wireless communication with the terminal device 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.

  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 and a wakeup determiner 132. 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 receiving wakeup signal WKE via antenna 11, wakeup signal receiver 131 demodulates received wakeup signal WKE and outputs the demodulated wakeup signal WKE to 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 wakeup ID matches the ID of the radio base station 1, the wakeup determiner 132 generates an activation signal and outputs the generated activation signal to the host system 143 of the main device 14. On the other hand, when it is determined that the wakeup ID does not match the ID of the wireless base station 1, the wakeup determination unit 132 discards the extracted wakeup ID.

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.

  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.

In addition, the host system 143 holds the channel Y that was used for transmitting and receiving 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 wakeup determination unit 132 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 wakeup determination unit 132, 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 The 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 holds in advance a time T _retry required to transmit the wakeup signal WKE once and an allowable delay time T _delay required to connect to the wireless base station.

  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.

When the wireless communication module 22 does not receive the wakeup notification WN or the active notification AN for a certain period after broadcasting the wakeup signal WKE, the wireless communication module 22 increases the transmission power and broadcasts the wakeup signal WKE again. Thereafter, when the wireless communication module 22 does not receive the wakeup notification WN or the active notification AN for a certain period, the wireless communication module 22 further increases the transmission power and broadcasts the wakeup signal WKE again. Wireless communication module 22 performs repeated until the operation number of times of transmission of the wake-up signal WKE reaches the maximum number of transmissions R _max.

Note that the maximum number of transmissions R _max is a maximum integer that does not exceed the division result obtained by dividing the allowable delay time T _delay by the time T _retry .

  Then, after broadcasting the wake-up signal WKE, the wireless communication module 22 transmits 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 through 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 conceptual diagram for explaining a method of activating a radio base station in the first embodiment. FIG. 5 is a conceptual diagram of a table showing the relationship between the number of transmissions and transmission power.

  With reference to FIG. 4, the radio base station CN to which the terminal apparatus 10 is to connect is outside the communication ranges REG1 and REG2 of the terminal apparatus 10 and exists within the communication range REG3 of the terminal apparatus 10. The communication ranges REG <b> 1 to REG <b> 3 are reachable areas of the wake-up signal WKE defined by the transmission power of the terminal device 10. Therefore, the wake-up signal WKE is transmitted farther as the transmission power of the terminal device 10 increases.

  The wireless communication module 22 of the terminal device 10 holds a table TBL1 shown in FIG. Referring to FIG. 5, table TBL1 includes the number of transmissions and transmission power. The number of transmissions and the transmission power are associated with each other. The number of transmissions is the number of transmissions of the wakeup signal WKE, and the transmission power is the transmission power of the wakeup signal WKE.

The transmission power (= 0 [dBm]) when the number of transmissions is the first is an initial value of the transmission power, and may consist of the previous power value that was able to wake up the radio base station. The power value may reach the wake-up signal WKE up to the range of data communication in the WLAN.

  When the wireless communication module 22 of the terminal device 10 broadcasts the wakeup signal WKE for the first time, the wireless communication module 22 detects the transmission power of 0 [dBm] with reference to the table TBL1, and uses the detected transmission power of 0 dBm. Broadcast WKE. The transmission power of 0 [dBm] is transmission power that can transmit the wakeup signal WKE into the communication range REG1.

  Since the radio base station CN cannot receive the wakeup signal WKE, neither the wakeup notification WN nor the active notification AN is transmitted to the terminal device 10.

  When the wireless communication module 22 of the terminal device 10 does not receive the wakeup notification WN or the active notification AN from the wireless base station CN within a certain period after the wakeup signal WKE is first broadcasted, the wireless communication module 22 refers to the table TBL1. Then, 4 [dBm] transmission power corresponding to the second transmission count is detected. The transmission power of 4 [dBm] is transmission power capable of transmitting the wakeup signal WKE into the communication range REG2.

  Also in this case, since the radio base station CN cannot receive the wakeup signal WKE, neither the wakeup notification WN nor the active notification AN is transmitted to the terminal device 10.

  When the wireless communication module 22 of the terminal device 10 does not receive the wakeup notification WN or the active notification AN from the wireless base station CN within a certain period after the wakeup signal WKE is broadcast for the second time, the wireless communication module 22 refers to the table TBL1. Thus, a transmission power of 10 [dBm] corresponding to the third transmission count is detected. The transmission power of 10 [dBm] is a transmission power capable of transmitting the wakeup signal WKE into the communication range REG3.

  The radio base station CN receives the wakeup signal WKE and shifts from the sleep state to the activated state. Then, the radio base station CN generates a wake-up notification WN and transmits it to the terminal device 10. The radio base station CN generates an active notification AN and transmits it to the terminal device 10 when receiving the wakeup signal WKE during activation.

  Then, the terminal device 10 receives the wakeup notification WN from the radio base station CN, and unicasts the wakeup notification response RWN to the radio base station CN. Thereafter, the terminal apparatus 10 receives the beacon frame Beacon from the radio base station CN on the channel Y, associates the radio base station CN with the IEEE 802.11 on the channel Y, and establishes a radio link with the radio base station CN. Then, the terminal device 10 performs radio communication with the radio base station CN through the channel Y.

  When the terminal apparatus 10 receives the active notification AN from the radio base station CN, the terminal apparatus 10 does not transmit the wake-up notification response RWN to the radio base station CN, but immediately communicates with the radio base station CN via the channel Y. .11 and establish a radio link with the radio base station CN.

Thus, the terminal device 10 within the range of the maximum transmission number _{R max} of the wake-up signal WKE, until it receives a wake-up notification WN or active notification AN, wake-up signal while increasing the transmission power according to the table TBL1 WKE Is repeatedly broadcast to connect to the radio base station CN.

FIG. 6 shows the terminal device 10 and the radio base station C when the radio base station CN is in the sleep state.
It is a flowchart for demonstrating operation | movement of N. In FIG. 6, a vertical dotted line below the host system 143 means that the host system 143 is in a sleep state, and a vertical solid line means that the host system 143 is in an activated state. Further, in FIG. 6, assuming that the terminal device 10 broadcasts a wakeup signal WKE while increasing the transmission power, the radio base station CN receives a wake-up signal WKE within the scope of the maximum transmission number R _max Operations of the terminal device 10 and the radio base station CN will be described.

  Referring to FIG. 6, terminal apparatus 10 broadcasts wakeup signal WKE on channel X by the above-described operation (step S1). Then, the wakeup device 13 of the radio base station CN receives the wakeup signal WKE via the antenna 11 on the channel X, demodulates the received wakeup signal WKE, and extracts the wakeup ID. Thereafter, the wakeup device 13 of the radio base station CN determines that the wakeup ID matches the ID of the radio base station CN, generates an activation signal, and outputs it to the host system 143 (step S2).

  Then, the host system 143 of the radio base station CN shifts from the sleep state to the activated state according to the activation signal (step S3). Then, the host system 143 of the radio base station CN generates a command signal COM2 and outputs it to the radio communication module 141. Thereafter, the host system 143 of the radio base station CN generates a wakeup notification WN including the channel Y and the address of the radio base station CN, and outputs the generated wakeup notification WN to the radio communication module 141.

  The wireless communication module 141 of the wireless base station CN shifts from the sleep state to the activated state in response to the command signal COM2 from the host system 143. When the wireless communication module 141 of the wireless base station CN receives the wakeup notification WN from the host system 143, the wireless communication module 141 modulates the received wakeup notification WN according to the modulation method of the wireless LAN, and sends the modulated wakeup notification WN. It transmits to the terminal device 10 via the antenna 12 on the channel X (step S4).

  The wireless communication module 22 of the terminal device 10 receives the wakeup notification WN on the channel X via the antenna 21 and outputs the received wakeup notification WN to the host system 23.

  The host system 23 of the terminal device 10 receives the wakeup notification WN from the wireless communication module 22, extracts the channel Y from the received wakeup notification WN, and outputs it to the wireless communication module 22. Further, the host system 23 of the terminal apparatus 10 generates a wakeup notification response RWN according to the wakeup notification WN and outputs the response to the wireless communication module 22.

  The wireless communication module 22 of the terminal device 10 receives the wake-up notification response RWN from the host system 23, modulates the received wake-up notification response RWN according to the modulation method of the wireless LAN, and transmits the modulated wake-up notification response RWN as a channel. X is unicast to the radio base station CN (step S5).

  The wireless communication module 141 of the wireless base station CN receives the wakeup notification response RWN on the channel X via the antenna 12 and outputs the received wakeup notification response RWN to the host system 143.

The host system 143 of the radio base station CN receives the wake-up notification response RWN from the radio communication module 141, and detects that the terminal device 10 has detected the transition of the radio base station CN to the activated state.

  Then, the host system 143 of the radio base station CN instructs the radio communication module 141 to change the channel. The wireless communication module 141 of the wireless base station CN changes the channel to channel Y in response to an instruction from the host system 143 (step S6).

  Similarly, the wireless communication module 22 of the terminal device 10 changes the channel to the channel Y (step S7).

  After that, the host system 143 of the radio base station CN generates a beacon frame Beacon, outputs it to the radio communication module 141, and instructs the radio communication module 141 to perform association with the terminal device 10.

  Then, the radio communication module 141 of the radio base station CN transmits a beacon frame Beacon on channel Y in response to an instruction from the host system 143.

  Then, the host system 143 of the radio base station CN performs IEEE 802.11 association with the terminal device 10 on the channel Y via the radio communication module 141 (step S8), and establishes a radio link with the terminal device 10. .

  Thereafter, the host system 143 of the radio base station CN performs radio communication with the terminal device 10 through the channel Y via the radio communication module 141 (step S9).

  As a result, a series of operations is completed.

  In this way, when the radio base station CN receives the wakeup signal WKE from the terminal device 10 in the sleep state, the radio base station CN shifts from the sleep state to the activated state, and transmits the wakeup notification WN to the terminal device 10; The reception of the wake-up notification response RWN from the terminal device 10 is performed on the channel X, and the IEEE 802.11 association and the wireless communication with the terminal device 10 are performed on the channel Y.

  FIG. 7 is a flowchart for explaining operations of the terminal device 10 and the radio base station CN when the radio base station CN is in an activated state.

  Referring to FIG. 7, when a series of operations is started, terminal apparatus 10 broadcasts wakeup signal WKE on channel X according to the above-described operation (step S11).

  Then, the wakeup device 13 of the radio base station CN receives the wakeup signal WKE via the antenna 11 on the channel X, demodulates the received wakeup signal WKE, and extracts the wakeup ID. Thereafter, the wakeup device 13 of the radio base station CN determines that the wakeup ID matches the ID of the radio base station CN, generates an activation signal, and outputs it to the host system 143 (step S12).

  Then, the host system 143 of the radio base station CN instructs the radio communication module 141 to change the channel to the channel X according to the activation signal. The radio communication module 141 of the radio base station CN changes the channel to the channel X in response to an instruction from the host system 143 (step S13).

Thereafter, the host system 143 of the radio base station CN generates an active notification AN including the channel Y and the address of the radio base station CN and outputs the active notification AN to the radio communication module 141. The radio communication module 141 receives from the host system 143. The active notification AN is modulated by the modulation method of the wireless LAN, and the modulated active notification AN is transmitted to the terminal device 10 through the channel X (step S14).

  The wireless communication module 22 of the terminal device 10 performs carrier sense via the antenna 21, receives the active notification AN on the channel X, demodulates the received active notification AN, and outputs the demodulated information to the host system 23.

  The host system 23 of the terminal device 10 detects that the radio base station CN is being activated in response to the active notification AN from the radio communication module 22. Then, the host system 23 of the terminal device 10 extracts the channel Y from the active notification AN, outputs it to the wireless communication module 22, and instructs the wireless communication module 22 to change the channel to the wireless communication channel Y.

  Then, the wireless communication module 22 of the terminal device 10 changes the channel to the channel Y in response to an instruction from the host system 23 (step S15).

  Similarly, the radio communication module 141 of the radio base station CN changes the channel to channel Y (step S16).

  After that, the host system 143 of the radio base station CN generates a beacon frame Beacon, outputs it to the radio communication module 141, and instructs the radio communication module 141 to perform association with the terminal device 10.

  Then, the radio communication module 141 of the radio base station CN transmits a beacon frame Beacon on channel Y in response to an instruction from the host system 143.

  Then, the host system 143 of the radio base station CN performs an IEEE 802.11 association with the terminal device 10 through the channel Y via the radio communication module 141 (step S17), and establishes a radio link with the terminal device 10. .

  Thereafter, the host system 143 of the radio base station CN performs radio communication with the terminal device 10 through the channel Y via the radio communication module 141 (step S18).

  As a result, a series of operations is completed.

  Thus, when the radio base station CN receives the wake-up signal WKE during activation, the radio base station CN transmits the active notification AN to the terminal device 10 without transmitting the wake-up notification WN to the terminal device 10, and then immediately An IEEE 802.11 association is established with the device 10 to establish a radio link.

When the radio base station CN is in the sleep state, it takes about 1 second until the association is started after the terminal apparatus 10 transmits the wakeup signal WKE, but the radio base station CN is in the activated state. In this case, the time required from when the terminal apparatus 10 transmits the wakeup signal WKE to when the association is started is about several tens of milliseconds. This is because the radio base station CN includes two antennas 11 and 12 and the radio base station CN can receive the wake-up signal WKE using the antenna 11 even when the radio base station CN performs radio communication using the antenna 12. This is because the wakeup notification WN and the wakeup notification response RWN are not exchanged between the terminal device 10 and the radio base station CN when the station CN is in the activated state (see FIG. 7).

  Therefore, when the radio base station CN is in the activated state, the terminal device 10 can quickly start radio communication with the radio base station CN.

  FIG. 8 is a flowchart for explaining the operation of the terminal device 10. Referring to FIG. 8, when the operation of terminal apparatus 10 is started, radio communication module 22 of terminal apparatus 10 receives wakeup signal WKE from wakeup signal generator 231, and the number of transmissions t of wakeup signal WKE t Is set to t = 1 (step S21).

  Then, the wireless communication module 22 of the terminal device 10 refers to the table TBL1, detects the transmission power PWt corresponding to the number of transmissions t, and broadcasts the wakeup signal WKE on the channel X using the detected transmission power PWt. (Step S22).

  Thereafter, the wireless communication module 22 of the terminal device 10 determines whether or not the wakeup notification WN or the active notification AN has been received within T1 seconds (step S23). Note that T1 is set to 1 second, for example.

  When it is determined in step S23 that the wakeup notification WN or the active notification AN has been received within T1 seconds, the wireless communication module 22 of the terminal device 10 wakes up with the received wakeup notification WN or the active notification AN. The received signal strength of the notification WN or the active notification AN is output to the host system 23.

  Then, when the host system 23 of the terminal device 10 receives a plurality of wake-up notifications WN and active notifications AN, it determines a connection-destination radio base station (step S24). More specifically, when the host system 23 of the terminal device 10 receives only the wakeup notification WN or only the active notification AN from a plurality of radio base stations, the wakeup notification WN having the highest received signal strength or the most received signal is received. A radio base station that has transmitted an active notification AN having a high signal strength is determined as a connection-destination radio base station. The host system 23 of the terminal device 10 selects any one of the maximum received signal strengths from the plurality of maximum received signal strengths when there are a plurality of maximum received signal strengths, and the selected maximum received signal strength. The radio base station that has transmitted the wake-up notification WN having the signal strength or the active notification AN is determined as the connection-destination radio base station.

  Further, when the host system 23 of the terminal device 10 receives both the wake-up notification WN and the active notification AN from a plurality of radio base stations, the maximum of the active notification AN among the plurality of received signal strengths of the active notification AN. If the received signal strength is greater than or equal to the reference value RSSI_std1, the radio base station that has transmitted the active notification AN having the maximum received signal strength is determined as the connection-destination radio base station. On the other hand, if the maximum received signal strength of the active notification AN is not equal to or greater than the reference value RSSI_std1, the radio base station that has transmitted the wake-up notification WN having the maximum received signal strength is determined as the connection-destination radio base station. When there are a plurality of maximum received signal strengths, an arbitrary one of the received signal strengths is selected from the plurality of maximum received signal strengths, and a wake-up notification WN having the selected maximum received signal strength is selected. The transmitted radio base station is determined as a connection-destination radio base station. Further, the reference value RSSI_std1 is set to −70 [dBm], for example.

  After step S24, the host system 23 of the terminal device 10 determines whether or not a wake-up notification WN has been received from the connection-destination radio base station (step S25).

When it is determined in step S25 that the wake-up notification WN has been received from the connection-destination radio base station, the host system 23 of the terminal device 10 extracts the channel Y from the wake-up notification WN, and the extracted channel Y is wirelessly transmitted. In addition to outputting to the communication module 22, a wake-up notification response RWN is generated and output to the wireless communication module 22. The wireless communication module 22 of the terminal device 10 receives the channel Y and the wake-up communication response RWN from the host system 23. Then, the wireless communication module 22 of the terminal device 10 modulates the wake-up notification response RWN by the modulation method of the wireless LAN, and transmits the modulated wake-up notification response RWN to the connection-destination wireless base station through the channel X (step S26).

  Then, after step S26 or when it is determined in step S25 that the wake-up notification WN has not been received from the connection-destination radio base station, the host system 23 of the terminal device 10 changes the channel to channel Y (= service channel). The wireless communication module 22 is instructed to change the channel to the service channel (= channel Y) according to the instruction from the host system 23 (step S27).

  In step S25, it is determined that the wake-up notification WN has not been received from the connection-destination radio base station, and the series of operations proceeds to step S27 when the terminal device 10 receives the active notification AN. is there.

  After that, the host system 23 of the terminal device 10 performs an IEEE 802.11 association with the connection-destination wireless base station through the channel Y via the wireless communication module 22 (step S28).

  Then, the host system 23 of the terminal device 10 determines whether or not the association is successful (step S29).

  When it is determined in step S29 that the association has not been successful, the host system 23 of the terminal device 10 instructs the wireless communication module 22 to change the channel to channel X (= wake-up channel), and the wireless communication module 22 changes the channel to the wake-up channel (= channel X) according to the instruction of the host system 23 (step S30). Thereafter, the series of operations proceeds to step S21.

On the other hand, when it is determined in step S23 that the wakeup notification WN or the active notification AN has not been received within T1 seconds, the wireless communication module 22 of the terminal device 10 determines that the transmission count t of the wakeup signal WKE is the maximum transmission count. It is further determined whether or not R _max has been reached (step S31).

In step S31, when the number of transmission times t of the wake-up signal WKE is found not reached the maximum number of transmissions _{R max,} the wireless communication module 22 of the terminal device 10 sets t = t + 1 (step S32), T2 Wait for seconds (step S33). This T2 is set to 5 seconds, for example. Then, after step S33, the series of operations proceeds to step S22.

On the other hand, in step S31, when the number of transmission times t of the wake-up signal WKE is determined to have reached the maximum number of transmissions R _max, the wireless communication module 22 of the terminal device 10, the number of transmission times t to initialize, through the antenna 21 Scanning is performed (step S34).

Then, the host system 23 of the terminal device 10 determines whether or not a desired radio base station has been found by determining whether or not the beacon frame Beacon has been received via the antenna 21 and the radio communication module 22. (Step S35). In this case, when the host system 23 of the terminal device 10 determines that the beacon frame Beacon has been received, the host system 23 determines that the desired radio base station has been found, and when the host system 23 has not received the beacon frame Beacon, the desired radio base station Is determined not to have been found.

  When it is determined in step S35 that a desired radio base station has been found, the series of operations proceeds to step S28 described above.

  On the other hand, when it is determined in step S35 that the desired radio base station has not been found, the host system 23 of the terminal device 10 changes the connection destination to the next ESSID if a plurality of connection destination ESSIDs are set. (Step S36). More specifically, the host system 23 of the terminal device 10 outputs the next ESSID to the wakeup signal generator 231, and the wakeup signal generator 231 generates a new wakeup ID based on the next ESSID. Then, a wakeup signal WKE including the generated wakeup ID is generated and output to the wireless communication module 22. Then, the wireless communication module 22 of the terminal device 10 broadcasts the wakeup signal WKE on the channel X while increasing the transmission power PWt by the method described above.

  When step S36 ends, the series of operations proceeds to step S33 described above.

  Then, in step S29, the above-described steps S21 to S36 are repeatedly executed until it is determined that the association is successful. If it is determined in step S29 that the association is successful, the series of operations ends.

The wireless communication module 22 of the terminal device 10 executes a loop including “NO” in steps S22 and S23, “NO” in S31, S32, and S33 a plurality of times, so that the table is within the range of the maximum number of transmissions R _max. The wakeup signal WKE is broadcast while increasing the transmission power PWt with reference to TBL1. Therefore, the terminal device 10 broadcasts the wake-up signal WKE according to the loop composed of “NO” in steps S22 and S23, “NO” in S31, S32, and S33, so that the wake-up signal WKE gradually increases from the terminal device 10. Reach far.

  As a result, in principle, the radio base station (any one of the radio base stations 1 to n) that is closest to the terminal device 10 first receives the wake-up signal WKE and shifts from the sleep state to the activated state.

  Even when the radio base station (any one of the radio base stations 1 to n) cannot correctly receive the wake-up signal WKE from the terminal device 10 due to fading or the like, the radio base station (radio base station 1) closer to the terminal device 10 Any one of -n) correctly receives the wake-up signal WKE and shifts from the sleep state to the activated state.

  Therefore, even if a network identifier (ESSID) is assigned to a plurality of radio base stations 1 to n, a smaller number of radio base stations can be shifted from a sleep state to an activated state, and a plurality of radio base stations are activated simultaneously. Can reduce waste.

  In step S35, when it is determined that a desired radio base station has been found, the terminal device 10 does not employ a method of shifting from the sleep state to the activated state by the wakeup signal WKE. This is because the terminal device 10 can be connected to the radio base station.

Furthermore, the terminal device 10 can be connected to the radio base station CN within the allowable delay time T _delay by setting the maximum number of transmissions R _max to an integer that does not exceed the division result obtained by dividing the allowable delay time T _delay by the time T _retry. .

  Furthermore, when the terminal apparatus 10 receives only the wakeup notification WN or only the active notification AN in step S24, the wireless base station that has transmitted the wakeup notification WN or the active notification AN having the maximum received signal strength is connected to the connection destination. By determining as a wireless base station, the terminal device 10 can be connected to the wireless base station closest to the terminal device 10.

  Furthermore, when the terminal apparatus 10 receives both the wake-up notification WN and the active notification AN in step S24, the wireless base station that has transmitted the active notification AN having the maximum received signal strength is preferentially connected to the wireless device to which it is connected. By determining as a base station, the terminal device 10 can be quickly connected to the radio base station. In addition, the number of radio base stations to be newly activated (service is started) is suppressed by preferentially connecting the terminal device 10 to a radio base station that is already activated (a radio base station that is providing a service). Thus, power saving can be achieved.

  FIG. 9 is a flowchart for explaining the operation of the radio base station. Referring to FIG. 9, when a series of operations is started, host systems 143 of radio base stations 1 to n receive the activation signal from wakeup device 13 and shift from the sleep state to the activation state (step S41). .

  Then, the host systems 143 of the radio base stations 1 to n generate a wakeup notification WN including the channel Y and its own address, and the generated wakeup notification WN is transmitted to the channel via the radio communication module 141 and the antenna 12. X is transmitted to the terminal device 10 (step S42).

  Thereafter, the host systems 143 of the radio base stations 1 to n determine whether or not the wakeup notification response RWN has been received within T3 seconds (step S43). Note that T3 is set to 1 second, for example.

  When it is determined in step S43 that the wake-up notification response RWN has not been received within T3 seconds, the host systems 143 of the wireless base stations 1 to n output the command signal COM1 and the wireless communication module 141 and the wired communication module 142 shifts to the sleep state, and itself shifts to the sleep state. That is, the main devices 14 of the radio base stations 1 to n again shift to the sleep state (step S44).

  On the other hand, when it is determined in step S43 that the wakeup notification response RWN has been received within T3 seconds, the host systems 143 of the radio base stations 1 to n change the channel to channel Y (= service channel). The wireless communication module 141 is instructed, and the wireless communication module 141 changes the channel to the service channel (= channel Y) in accordance with the instruction from the host system 143. Thereafter, the host systems 143 of the radio base stations 1 to n perform radio communication with the terminal device 10 via the channel Y via the radio communication module 141. That is, the host systems 143 of the radio base stations 1 to n start service (step S45).

  And a series of operation | movement is complete | finished after step S44 or step S45.

In this way, the radio base stations 1 to n transmit the wake-up notification WN after the wake-up signal WKE from the terminal device 10 has shifted from the sleep state to the wake-up state.
If the wakeup notification response RWN is not received within 3 seconds, the process again shifts to the sleep state (see “NO” in step S41, step S42, and step S43, and step S44).

  Therefore, even if a plurality of radio base stations are activated by the wake-up signal WKE, the radio base station that does not receive the wake-up notification response RWN from the terminal device 10 within T3 seconds shifts to the sleep state and wakes-up notification response RWN. Since only the radio base station that has received the signal maintains the activated state, wasteful activation of a plurality of radio base stations can be suppressed.

  Note that the transmission power in the table TBL1 is not limited to the values shown in FIG. 5, but may be other values. Further, the increase rate of the transmission power with respect to the increase in the number of transmissions is not limited to the increase rate shown in FIG. 5, and may be another increase rate. Furthermore, the initial value of the transmission power is not limited to 0 [dBm], and may be another value. In Embodiment 1, the initial value of the transmission power and the increase rate of the transmission power according to the connection status between the terminal device 10 and the radio base stations 1 to n and the distribution status of the radio base stations 1 to n in the past. May be changed.

  In the first embodiment, the wakeup signal generator 231 that generates the wakeup signal WKE constitutes “signal generation means”.

Furthermore, in the first embodiment, the wireless communication module 22 that transmits the wakeup signal WKE while increasing the transmission power until the wakeup notification WN or the active notification AN is received within the range of the maximum number of transmissions R _max . "Transmission means" is configured.

  Furthermore, in the first embodiment, the host system 23 that receives a plurality of wake-up notifications WN and active notifications AN and determines a connection-destination radio base station constitutes “communication means”.

[Embodiment 2]
FIG. 10 is a configuration diagram of radio base stations 1 to n in the second embodiment. In the second embodiment, the radio base stations 1 to n include the radio base station 1A shown in FIG.

  In the second embodiment, it is assumed that terminal apparatus 10 transmits wakeup signal WKE with constant transmission power PW.

  Referring to FIG. 10, radio base station 1A is obtained by replacing wakeup device 13 of radio base station 1 shown in FIG. 2 with wakeup device 13A, main device 14 with main device 14A, and others. This is the same as the radio base station 1.

  The wakeup device 13A is the same as the wakeup device 13 except that a signal generator 133 is added to the wakeup device 13 shown in FIG.

  The main device 14A is the same as the main device 14 except that the host system 143 of the main device 14 shown in FIG.

  In the second embodiment, the wireless communication module 141 receives a beacon frame Beacon from another wireless base station via the antenna 12 and outputs the received beacon frame Beacon to the host system 143A.

  The host system 143A holds in advance transmission power PW (= constant value) used by the terminal device 10 for transmission of the wakeup signal WKE.

  Further, the host system 143A estimates the number N of radio base stations existing around the terminal apparatus 10 based on the received signal strength RSSI_STA and the transmission power PW in a period of one week or one month, for example. .

  Then, the host system 143A outputs the estimated number N of radio base stations to the signal generator 133.

  Further, the host system 143A shifts from the sleep state to the start state in response to the start signal from the signal generator 133.

  In addition, the host system 143A performs the same function as the host system 143.

  The signal generator 133 holds a constant α in advance. This constant α is a constant for adjusting the number of radio base stations to be activated, and is determined in advance by the designer of the radio communication system 100. The constant α is set to a value smaller than the number N of radio base stations.

When the signal generator 133 receives the number N of radio base stations from the host system 143A, the signal generator 133 uses the number N of radio base stations and a constant α to calculate an activation probability Z ₁ that is a probability for activating the radio base station. Operate with an expression.

  When the signal generator 133 receives from the wakeup determination unit 132 a match signal MTCH indicating that the wakeup ID matches the ID of the radio base station 1A, the signal generator 133 generates a random number RN by the built-in random number generator. The random number RN is a number that satisfies 0 ≦ RN <1.

Then, the signal generator 133, the generated random number RN is equal to or less than start probability Z _1, if the activation probability Z ₁ less the generated random number RN, and generates an activation signal hosts outputs to the system 143A, when the generated random number RN is greater than start probability Z _1, without generating an activation signal, no output to the host system 143A.

  In the second embodiment, the wakeup determination unit 132 determines whether or not the wakeup ID matches the ID of the radio base station 1A, and determines that the wakeup ID matches the ID of the radio base station 1A. Then, the coincidence signal MTCH is generated and output to the signal generator 133. Further, when the wakeup determination unit 132 determines that the wakeup ID does not match the ID of the radio base station 1A, the wakeup determination unit 132 outputs nothing to the signal generator 133.

Accordingly, in the second embodiment, the main device 14A coincides wakeup ID is the ID of the radio base station 1A, and when the random number RN is equal to or less than the activation probability Z _1, and the transition from the sleep state to the active state when the wake-up ID does not match the ID of the radio base station 1A, or when random number RN is greater than start probability Z _1, maintains the sleep state.

  In the second embodiment, the power supply 15 supplies 100 μW of power to the wakeup device 13A and supplies 7 W of power to the main device 14A.

  FIG. 11 is a conceptual diagram for explaining a method of estimating the number N of radio base stations existing around the terminal device 10. In FIG. 11, a triangular mark represents a radio base station other than the radio base station 1 </ b> A.

  Referring to FIG. 11, terminal apparatus 10 has a communication range REG4 in which wakeup signal WKE can be reached with constant transmission power PW.

  The host system 143A of the radio base station 1A receives the beacon frame Beacon from the radio base stations existing around the radio base station 1A via the radio communication module 141, and based on the received beacon frame Beacon, the radio base station The number M of wireless base stations existing around 1A (M is a positive integer) is counted.

In addition, the host system 143A of the radio base station 1A holds in advance a range (= area _SAP ) in which the radio base station 1A can receive the beacon frame Beacon. The area S _AP a beacon frame Beacon determines the possible distance reaching from the received signal strength of the beacon frame Beacon, is determined as the area of a circle the distance the determined radius.

Then, the host system 143A of the radio base station 1A calculates the density of radio base stations existing around the radio base station 1A by M / _SAP .

Thereafter, the host system 143A of the radio base station 1A calculates (M / S _AP ) π (D _MAX ) ² using the distance D _MAX that the wakeup signal WKE from the terminal device 10 can reach. The host system 143A of the radio base station 1A holds the relationship between the transmission power and the distance and the transmission power when the terminal device 10 transmits the wakeup signal WKE. A distance corresponding to the power is detected from the relationship between the transmission power and the distance, and the detected distance is defined as a distance D _MAX .

Then, the host system 143A of the radio base station 1A assumes that the density of radio base stations existing around the terminal device 10 is the same as the density M / _SAP of the radio base stations existing around the radio base station 1A. Then, (M / S _AP ) π (D _MAX ) ² is estimated as the number N of radio base stations existing around the terminal device 10.

  FIG. 12 is a flowchart for explaining the operation of the radio base station 1A in the second embodiment.

  The flowchart shown in FIG. 12 is the same as the flowchart shown in FIG. 9 except that step S41 of the flowchart shown in FIG. 9 is replaced with steps S41A, S41B, S41C, S41D, and 41E.

  Referring to FIG. 12, in wakeup device 13A of radio base station 1A, wakeup signal receiver 131 receives wakeup signal WKE on channel X via antenna 11 (step S41A). The up signal WKE is demodulated. Then, wakeup signal receiver 131 outputs the demodulated wakeup signal WKE to wakeup determiner 132.

  The wakeup determiner 132 receives the wakeup signal WKE from the wakeup signal receiver 131, and determines whether or not the wakeup ID included in the received wakeup signal WKE matches the ID of the radio base station 1A. (Step S41B).

  When it is determined in step S41B that the wake-up ID does not match the ID of the radio base station 1A, the series of operations proceeds to step S44.

  On the other hand, when it is determined in step S41B that the wakeup ID matches the ID of the radio base station 1A, the wakeup determiner 132 generates a match signal MTCH and outputs it to the signal generator 133.

The signal generator 133 receives the coincidence signal MTCH from wakeup determiner 132, a random number RN generated by the internal random number generator (step S41C), the generated random number RN is a start probability _{Z 1} or less Whether or not (step S41D).

In step S41D, when the random number RN is judged to be larger than the start probability _{Z 1,} a series of operations proceeds to step S44.

On the other hand, in step S41D, when the random number RN is judged to be less activated probability Z _1, signal generator 133 generates a start signal, and outputs the generated activation signal to the host system 143A.

  Then, the host system 143A shifts from the sleep state to the start state according to the start signal from the signal generator 133 (step S41E).

  Thereafter, the above-described steps S42 to S45 are executed, and a series of operations is completed.

Thus, in the second embodiment, radio base stations 1 to n (= 1A) are determined that the wake-up ID matches the ID of radio base stations 1 to n (= 1A), and the random number RN is When the activation probability Z is ₁ or less, the sleep state is shifted to the activation state (see “YES” in step S41B, “YES” in S41C, S41D, and S41E). The activation probability Z ₁ is determined so as to be inversely proportional to the number N of radio base stations existing around the terminal device 10. Thus, activation probability Z ₁ is The more the number N of the wireless base station is relatively, relatively smaller, the number N of radio base stations if relatively minor, relatively large.

As a result, when the radio base stations 1 to n (= 1A) receive the wake-up signal WKE, the radio base stations 1 to n (= 1A) shift from the sleep state to the activated state with a smaller probability than in the first embodiment, and the terminal device 10 wakes up. The number of radio base stations that shift to the activated state by transmitting the signal WKE is smaller than that in the first embodiment. Then, even when the radio base station having transferred to an activated state with the activation probability Z ₁ there are a plurality, the radio base station does not receive a wakeup notification response RWN again, to shift to a sleep state (step S43 " NO ", see S44). Therefore, the number of radio base stations that shift to the sleep state again after the transition from the sleep state to the start state and then the wake-up notification response RWN is not received is greater than in the first embodiment. Less. Therefore, it is possible to further suppress the waste of a plurality of radio base stations shifting to the activated state at the same time as in the first embodiment.

In Embodiment 2, for example, when the estimated number N of radio base stations is “10”, the constant α is set to “1”, for example. As a result, start probability _{Z 1} of the radio base station 1 to n (= 1A) becomes 1/10, 10 of the radio base stations existing in the communication range REG4 of the terminal apparatus 10 is its 10% One radio base station is activated in response to reception of the wake-up signal WKE. As a result, due to not receiving the wake-up notification response RWN, the number of radio base stations that shift to the sleep state becomes “0” again, and it is possible to eliminate the radio base stations that are temporarily activated. .

  Note that the operations of the terminal device 10 and the radio base station CN (= 1A) in Embodiment 2 when the radio base station CN (= 1A) is in the sleep state are executed according to the flowchart shown in FIG. Further, the operation of the terminal device 10 and the radio base station CN (= 1A) in the second embodiment when the radio base station CN (= 1A) is in an activated state is executed according to the flowchart shown in FIG. Furthermore, the operation of the terminal device 10 in the second embodiment is executed according to the flowchart shown in FIG.

  In the above description, the terminal apparatus 10 is described as broadcasting the wake-up signal WKE with a constant transmission power PW. However, in the second embodiment, the terminal apparatus 10 is not limited to this, and the terminal apparatus 10 is as in the first embodiment. The wake-up signal WKE may be broadcast while increasing the transmission power.

In this case, the radio base station 1A, for each transmission power of the terminal apparatus 10, and estimates the number N of radio base stations existing around the terminal apparatus 10 obtains the activation probability Z _1. Then, the radio base station 1A shifts from the sleep state to the active state using the activation probability Z ₁ determined for each transmission power of the terminal apparatus 10. As a result, for each transmission power of the terminal device 10, it is possible to suppress waste of a plurality of radio base stations shifting to the activated state at the same time.

  In the second embodiment, the wake-up signal receiver 131 that receives the wake-up signal WKE from the terminal device 10 constitutes “reception means”.

  In the second embodiment, determining whether or not the wakeup ID matches the ID of the radio base station 1A indicates whether or not the wakeup signal WKE indicates that the radio base station 1A is activated. This corresponds to determination. This is because if the wakeup signal WKE includes a wakeup ID and the wakeup ID matches the ID of the radio base station 1A, the radio base station 1A shifts from the sleep state to the activated state. Then, the wakeup determination unit 132 determines whether or not the wakeup ID matches the ID of the radio base station 1A. Therefore, the wakeup determination unit 132 constitutes “determination means”.

Furthermore, in the second embodiment, the signal generator 133 that generates the activation signal using the activation probability Z ₁ constitutes “activation means”.

  Furthermore, in the second embodiment, the host system 143A is activated in response to the activation signal from the signal generator 133, and thus constitutes “communication means”.

  Furthermore, in the second embodiment, the host system 143A estimates the number N of radio base stations existing around the terminal apparatus 10, and thus constitutes “estimating means”.

[Embodiment 3]
FIG. 13 is a configuration diagram of a radio base station in the third embodiment. In the third embodiment, the radio base stations 1 to n include the radio base station 1B shown in FIG.

  Referring to FIG. 13, radio base station 1B is the same as radio base station 1 except that wakeup device 13 of radio base station 1 shown in FIG. 2 is replaced with wakeup device 13B.

The wake-up device 13B is obtained by replacing the wake-up signal receiver 131 of the wake-up device 13 shown in FIG. 2 with a wake-up signal receiver 131A and adding a signal generator 133A. The same.

  The wakeup signal receiver 131A receives the wakeup signal WKE from the terminal device 10 via the antenna 11, and detects the received signal strength S when the wakeup signal WKE is received.

  Then, wakeup signal receiver 131A demodulates wakeup signal WKE and outputs the demodulated wakeup signal WKE to wakeup determiner 132. The wakeup signal receiver 131A outputs the detected received signal strength S to the signal generator 133A.

The signal generator 133A receives the received signal strength S from the wakeup signal receiver 131A, and receives the coincidence signal MTCH from the wakeup determiner 132. The signal generator 133A holds a constant β and a minimum received signal strength RSSI _min in advance. Here, the constant β is set to a value larger than the minimum received signal strength RSSI _min . The constant β, the minimum received signal strength RSSI _min, and the received signal strength S all have a negative dBm unit. Note that the minimum received signal strength RSSI _min is set to, for example, −90 [dBm].

  FIG. 14 is a conceptual diagram of a table showing the relationship between the number of receptions of the wakeup signal WKE and the constant β. Referring to FIG. 14, table TBL2 includes the number of receptions of wakeup signal WKE and a constant β. The number of receptions and the constant β are associated with each other. The constant β decreases as the number of receptions of the wakeup signal WKE increases.

  The signal generator 133A holds a table TBL2. When the signal generator 133A receives the coincidence signal MTCH from the wakeup determination unit 132, the signal generator 133A refers to the table TBL2 and detects a constant β corresponding to the number of receptions of the wakeup signal WKE.

Then, the signal generator 133A may determine the activation probability _{Z 2} of the radio base station 1B by the following equation using the detected constant beta, received signal strength S and the minimum received signal strength _{RSSI min.}

Signal generator 133A, when the received signal strength S is larger than the constant beta, is set to "1" to start probability Z _2. The setting signal generator 133A is the received signal strength S is the minimum received signal strength _{RSSI min} or more, and, when the received signal strength S is less than constant beta, activation probability _{Z 2} to "S / beta" To do. Further, the signal generator 133A, when the received signal strength S is less than the minimum received signal strength _{RSSI min,} is set to "0" to start probability _{Z 2.}

When the received signal strength S is smaller than the minimum received signal strength RSSI _min , the radio base station 1B does not shift from the sleep state to the activated state for the following reason.

Since the minimum received signal strength RSSI _min is set to −90 [dBm], in a wireless communication environment where the received signal strength S is smaller than −90 [dBm], the wake-up signal receiver 1
31A receives a radio signal with almost no noise level. Therefore, it is necessary to prevent the radio base station 1B from shifting to the activated state by a radio signal having a noise level.

Further, when the signal generator 133A newly receives the received signal strength S from the wakeup signal receiver 131A (that is, when the wakeup device 13B newly receives the wakeup signal WKE), the signal generator 133A sets the reception frequency to “1”. The constant β corresponding to the increased number of receptions is detected with reference to the table TBL2. The signal generator 133A may determine the activation probability Z ₂ by equation (2) using the detected constant beta.

  Furthermore, the signal generator 133A does not receive the received signal strength S from the wakeup signal receiver 131A for a certain time (for example, 10 seconds) (that is, the wakeup device 13B receives the wakeup signal WKE for a certain time. If not, the reception count is initialized to “0”.

The signal generator 133A, when asking for activation probability Z _2, as well as generating a random number RN by a built-in random number generator, if the generated random number RN is activated probability Z ₂ or less, and generates an activation signal output to the host system 143, if the generated random number RN is greater than start probability Z _2, nothing is output to the host system 143.

  In the third embodiment, the wakeup determination unit 132 determines whether or not the wakeup ID matches the ID of the radio base station 1B, as in the second embodiment, and the wakeup ID is the radio base station. When it is determined that it matches the ID of the station 1B, a match signal MTCH is generated and output to the signal generator 133A. Further, when the wakeup determination unit 132 determines that the wakeup ID does not match the ID of the radio base station 1B, the wakeup determination unit 132 outputs nothing to the signal generator 133A.

Accordingly, in the third embodiment, the main device 14, the wake-up ID matches the ID of the radio base station 1B, and when the random number RN is equal to or less than the activation probability Z _2, and the transition from the sleep state to the active state when the wake-up ID does not match the ID of the radio base station 1B, or when a random number RN is greater than start probability Z _2, maintains the sleep state.

  In the third embodiment, the power supply 15 supplies 100 μW of power to the wakeup device 13B and supplies 7 W of power to the main device 14.

The operation of radio base station 1B in the third embodiment is executed according to the flowchart shown in FIG. In this case, start probability _{Z 1} in step S41D is replaced by the start probability _{Z 2.}

As a result, the wireless base station 1 to n (= 1B) is the transition from the sleep state to the active state according to activation probability Z ₂ corresponding to the received signal strength S of the wake-up signal WKE. That is, the radio base station 1 to n (= 1B) is the greater received signal strength S is relatively shifted to an activated state at a relatively high activation probability Z _2, the received signal strength S is relatively small if, to shift to the start-up state at a relatively low start-up probability Z _2.

  Therefore, as the radio base stations 1 to n (= 1B) are closer to the terminal device 10, the probability of shifting to the activated state is higher, and the farther from the terminal device 10, the lower the probability of shifting to the activated state.

  Therefore, it is possible to further suppress the waste of a plurality of radio base stations shifting to the activated state at the same time as in the first embodiment.

  In addition, the constant β decreases as the number of receptions of the wakeup signal WKE increases. Therefore, even in a wireless communication environment in which the wakeup signal WKE is difficult to reach the wireless base station, the wireless base station to be shifted to the activated state is stably determined. it can.

  Note that the operations of the terminal apparatus 10 and the radio base station CN (= 1B) in Embodiment 3 when the radio base station CN (= 1B) is in the sleep state are executed according to the flowchart shown in FIG. Further, the operation of the terminal device 10 and the radio base station CN (= 1B) in the third embodiment when the radio base station CN (= 1B) is in an activated state is executed according to the flowchart shown in FIG. Furthermore, the operation of the terminal device 10 in the third embodiment is executed according to the flowchart shown in FIG.

  In the third embodiment, the wakeup signal receiver 131A receives the wakeup signal WKE from the terminal device 10 and detects the received signal strength when the wakeup signal WKE is received. Is configured.

  In the third embodiment, the wakeup determiner 132 constitutes “determination means” as in the second embodiment.

Further, in the third embodiment, the signal generator 133A for generating an activation signal with the activation probability Z ₂ constitutes "activation means".

  Furthermore, in the third embodiment, the host system 143 is activated in response to the activation signal from the signal generator 133A, and thus constitutes “communication means”.

[Embodiment 4]
FIG. 15 is a configuration diagram of a radio base station in the fourth embodiment. In the fourth embodiment, the radio base stations 1 to n include the radio base station 1C illustrated in FIG.

  Referring to FIG. 15, wireless base station 1C is the same as wireless base station 1A except that wakeup device 13A of wireless base station 1A shown in FIG. 10 is replaced with wakeup device 13C.

  The wakeup device 13C is obtained by replacing the wakeup signal receiver 131 of the wakeup device 13A shown in FIG. 10 with a wakeup signal receiver 131A, replacing the signal generator 133 with a signal generator 133B, This is the same as the wake-up device 13A.

  As described above, the wakeup signal receiver 131A demodulates the wakeup signal WKE and detects the received signal strength S when the wakeup signal WKE is received. The wakeup signal receiver 131A outputs the demodulated wakeup signal WKE to the wakeup determiner 132, and outputs the detected received signal strength S to the signal generator 133B.

  The signal generator 133B receives the coincidence signal MTCH from the wakeup determiner 132, receives the received signal strength S from the wakeup signal receiver 131A, and receives the number N of radio base stations from the host system 143A.

The signal generator 133B holds the constants α and β, the minimum received signal strength RSSI _min, and the table TBL2.

When the signal generator 133B receives the number N of radio base stations, the signal generator 133B obtains the activation probability Z ₁ by substituting the constant α and the number N of radio base stations into Equation (1).

In addition, when receiving the received signal strength S, the signal generator 133B refers to the table TBL2 and detects a constant β corresponding to the number of receptions of the wakeup signal WKE. The signal generator 133B, the detected constant beta, asks for activation probability _{Z 2} by equation (2) using the minimum received signal strength _{RSSI min} and the received signal strength S.

Then, the signal generator 133B calculates the activation probability Z by substituting the activation probabilities Z ₁ and Z ₂ into the following equation.

  The constant γ in the equation (3) is set to 0.1, for example, when the wireless communication system 100 is activated, for example, when the situation around each of the radio base stations 1 to n (= 1C) is not understood, When the situation around each of the radio base stations 1 to n (= 1C) is known, for example, 0.7 to 0.8 is set.

Thus, the signal generator 133B, when it is unknown surroundings of each radio base station 1 to n (= 1C), the activation probability Z at a weight to start probability Z ₂ than start probability Z ₁ When the determination is made and the situation around each of the radio base stations 1 to n (= 1C) is known, the activation probability Z is determined by weighting the activation probability Z ₁ rather than the activation probability Z ₂ .

Each of the radio base stations 1 to n (= 1C) is difficult to estimate the number N of radio base stations existing around the terminal device 10 when the surrounding situation of the terminal device 10 is not understood. better to determine the start probability Z at a weight to start probability Z ₂ which is determined in accordance with the received signal strength S of WKE can be stably determined radio base station to transition to active state. Therefore, each radio base station 1 to n (= 1C) decides the activation probability Z by placing a weight on the activation probability Z ₂ rather than the activation probability Z ₁ when the surrounding situation is not understood. It is.

On the other hand, each radio base station 1 to n (= 1C) can easily estimate the number N of radio base stations existing around the terminal device 10 when the situation around the radio base station 1 to n (= 1C) is understood. better to determine the start probability Z at a weight to start probability Z ₁ which is determined in accordance with the N may be determined radio base stations in accordance with the actual radio communication environment transition to active state. Therefore, each radio base station 1 to n (= 1C) decides the activation probability Z by weighting the activation probability Z ₁ rather than the activation probability Z ₂ when the surrounding situation is understood. is there.

The operation of radio base station 1C in the fourth embodiment is executed according to the flowchart shown in FIG. In this case, start probability _{Z 1} in step S41D is replaced by the start probability Z.

As a result, the radio base stations 1 to n (= 1C) correspond to the activation probability Z ₁ according to the number N of radio base stations existing around the terminal device 10 and the received signal strength S of the wake-up signal WKE. is the transition from the sleep state to the wake-up state in accordance with the start-up probability Z _2. That is, the radio base stations 1 to n (= 1C) are activated with a relatively high activation probability Z if the number N of radio base stations is relatively small and the received signal strength S is relatively large. If the number of radio base stations N is relatively large and the received signal strength S is relatively small, the transition to the activated state is performed with a relatively low activation probability Z.

  Therefore, the probability Z of the radio base station to shift to the activated state can be determined according to both the number N of radio base stations existing around the terminal device 10 and the received signal strength S of the wakeup signal WKE.

  In addition, the effects of the second and third embodiments can be enjoyed.

  Note that the operations of the terminal device 10 and the radio base station CN (= 1C) in Embodiment 4 when the radio base station CN (= 1C) is in the sleep state are executed according to the flowchart shown in FIG. Further, the operation of the terminal device 10 and the radio base station CN (= 1C) in the fourth embodiment when the radio base station CN (= 1C) is in an activated state is executed according to the flowchart shown in FIG. Furthermore, the operation of the terminal device 10 in the fourth embodiment is executed according to the flowchart shown in FIG.

  In the fourth embodiment, the wakeup signal receiver 131A constitutes “reception means” as in the third embodiment.

  In the fourth embodiment, the wakeup determination unit 132 constitutes “determination means” as in the second embodiment.

Furthermore, in the fourth embodiment, the signal generator 133B that generates the activation signal using the activation probability Z constitutes “activation means”. The activation probability Z ₂ constitutes a “first activation probability”, the activation probability Z ₁ constitutes a “second activation probability”, and the activation probability Z constitutes an “total activation probability”.

  Furthermore, in the fourth embodiment, the host system 143A is activated in response to the activation signal from the signal generator 133B, and thus constitutes “communication means”.

[Embodiment 5]
FIG. 16 is a configuration diagram of a radio base station in the fifth embodiment. In the fifth embodiment, the radio base stations 1 to n include the radio base station 1D shown in FIG.

  Referring to FIG. 16, the radio base station 1D is obtained by replacing the wake-up device 13 of the radio base station 1 shown in FIG. 2 with the wake-up device 13D, replacing the main device 14 with the main device 14B, and others. This is the same as the radio base station 1.

  The wakeup device 13D is the same as the wakeup device 13 except that the wakeup signal receiver 131 of the wakeup device 13 shown in FIG. 2 is replaced with a wakeup signal receiver 131D.

  The main apparatus 14B is the same as the main apparatus 14 except that the host system 143 of the main apparatus 14 shown in FIG.

  The wakeup signal receiver 131D receives the wakeup signal WKE via the antenna 11 and detects the received signal strength RSSI_WKE when the wakeup signal WKE is received. Then, wakeup signal receiver 131D demodulates wakeup signal WKE and outputs the demodulated wakeup signal WKE to wakeup determiner 132. The wakeup signal receiver 131D outputs the detected received signal strength RSSI_WKE to the host system 143B.

  Upon receiving the received signal strength RSSI_WKE from the wakeup signal receiver 131D, the host system 143B receives the received signal strength RSSI_WKE and wakeup advertisement WA (Wake) including status information Status indicating whether it is in a sleep state or an active state. -Up Advertisement). In this case, the status information Status includes Status (SLP) when the host system 143B is in a sleep state, and Status (DRV) when the host system 143B is in an activated state.

  Then, the host system 143B broadcasts the generated wakeup advertisement WA to other wireless base stations via the wireless communication module 141 and the antenna 12.

  In addition, the host system 143B receives the wake-up advertisement WA from another radio base station via the antenna 12 and the radio communication module 141. When the host system 143B receives the wake-up advertisement WA when the host system 143B is active, the host system 143B determines whether the wireless base station 1D is already connected to the terminal device 10 and is activated. Since there is no need to coordinate with the station, the wake-up advertisement WA is ignored.

  On the other hand, when the host system 143B receives the wakeup advertisement WA after the host system 143B shifts from the sleep state to the activated state, the received signal strength RSSI_WKE included in the wakeup advertisement WA is received from the wakeup signal receiver 131D. If it is larger than the strength RSSI_WKE, it shifts to the sleep state.

  Further, in the host system 143B, the status information Status (DRV) indicating that the host system 143B is in the activated state is included in the wakeup advertisement WA, and the received signal strength RSSI_WKE included in the wakeup advertisement WA is based on the reference value RSSI_std2. When the value is larger, the sleep mode is entered. The reference value RSSI_std2 is set to −70 [dBm], for example.

  In addition, the host system 143B performs the same function as the host system 143.

  In the fifth embodiment, the power supply 15 supplies 100 μW of power to the wakeup device 13D and supplies 7 W of power to the main device 14B.

  FIG. 17 is a flowchart for explaining operations of the radio base station and the terminal device in the fifth embodiment.

  In FIG. 17, radio base stations 1 (= 1D) and 2 (= 1D) are shown as a plurality of radio base stations having the same ESSID. Moreover, the vertical dotted line shown in FIG. 17 means that it is in the sleep state, and the vertical solid line means that it is in the activated state.

Referring to FIG. 17, terminal apparatus 10 broadcasts wakeup signal WKE on channel X through the above-described operation (step S61). Then, the wakeup device 13D of the radio base station 1 (= 1D) receives the wakeup signal WKE via the antenna 11 via the channel X, and detects the received signal strength RSSI_WKE1 when the wakeup signal WKE is received. Thereafter, the wakeup device 13D of the radio base station 1 (= 1D) outputs the detected received signal strength RSSI_WKE1 to the host system 143B. Further, the wakeup device 13D of the radio base station 1 (= 1D) demodulates the received wakeup signal WKE and extracts the wakeup ID. Then, the wakeup device 13D of the radio base station 1 (= 1D) has a wakeup ID of I of the radio base station 1 (= 1D).
It is determined that it matches D, and an activation signal is generated and output to the host system 143B (step S62).

  Then, the host system 143B of the wireless base station 1 (= 1D) shifts from the sleep state to the activated state according to the activation signal (step S63) and receives the received signal strength RSSI_WKE1. Then, the host system 143B of the wireless base station 1 (= 1D) generates a command signal COM2 and outputs it to the wireless communication module 141 and the wired communication module 142. The wireless communication module 141 and the wired communication module 142 of the wireless base station 1 (= 1D) shift from the sleep state to the activated state according to the command signal COM2.

  Similarly, the wakeup device 13D of the radio base station 2 (= 1D) receives the wakeup signal WKE on the channel X via the antenna 11, and detects the received signal strength RSSI_WKE2 of the wakeup signal WKE. In addition to outputting to the host system 143B, the activation signal is output to the host system 143B (step S64). The host system 143B shifts from the sleep state to the activation state according to the activation signal (step S65), and the received signal strength RSSI_WKE2 Receive. In addition, the wireless communication module 141 and the wired communication module 142 of the wireless base station 2 (= 1D) shift from the sleep state to the activated state according to the command signal COM2 from the host system 143B.

  Then, the host system 143B of the wireless base station 2 (= 1D) wakes up the advertisement WA1 = [RSSI_WKE2 / Status (SLP) including the received signal strength RSSI_WKE2 and the status information Status (SLP) indicating that it is in the sleep state. )] And broadcast the generated wake-up advertisement WA1 = [RSSI_WKE2 / Status (SLP)] to other radio base stations (step S66).

  Further, the host system 143B of the radio base station 1 (= 1D) wakes up the advertisement WA2 = [RSSI_WKE1 / Status (SLP) including the received signal strength RSSI_WKE1 and the status information Status (SLP) indicating that it is in the sleep state. )] And broadcast the generated wake-up advertisement WA2 = [RSSI_WKE1 / Status (SLP)] to other radio base stations (step S67).

  The host system 143B of the wireless base station 2 (= 1D) receives the wake-up advertisement WA2 = [RSSI_WKE1 / Status (SLP)] via the antenna 12 and the wireless communication module 141, and the received signal strength RSSI_WKE2 at the local station is wakened. Since it is smaller than the received signal strength RSSI_WKE1 included in the up advertisement WA2, the process shifts from the activated state to the sleep state (step S68).

  On the other hand, the host system 143B of the wireless base station 1 (= 1D) receives the wake-up advertisement WA1 = [RSSI_WKE2 / Status (SLP)] via the antenna 12 and the wireless communication module 141, and receives the received signal strength RSSI_WKE1 at the local station. Is larger than the received signal strength RSSI_WKE2 included in the wake-up advertisement WA1, so the activation state is maintained.

  Then, the host system 143B of the radio base station 1 (= 1D) generates a wakeup notification WN including the channel Y and the address of the radio base station 1 (= 1D), and wirelessly communicates the generated wakeup notification WN. Output to module 141.

When the wireless communication module 141 of the wireless base station 1 (= 1D) receives the wakeup notification WN from the host system 143B, the wireless communication module 141 modulates the received wakeup notification WN according to the modulation method of the wireless LAN, and the modulated wakeup notification WN is transmitted to terminal apparatus 10 via antenna 12 on channel X (step S69).

  The wireless communication module 22 of the terminal device 10 receives the wakeup notification WN on the channel X via the antenna 21 and outputs the received wakeup notification WN to the host system 23.

  The host system 23 of the terminal device 10 receives the wakeup notification WN from the wireless communication module 22, extracts the channel Y from the wakeup notification WN, and outputs it to the wireless communication module 22. Further, the host system 23 of the terminal apparatus 10 generates a wakeup notification response RWN according to the wakeup notification WN and outputs the response to the wireless communication module 22.

  The wireless communication module 22 of the terminal device 10 receives the wake-up notification response RWN from the host system 23, modulates the received wake-up notification response RWN according to the modulation method of the wireless LAN, and transmits the modulated wake-up notification response RWN as a channel. X is unicast to the radio base station 1 (= 1D) (step S70).

  The wireless communication module 141 of the wireless base station 1 (= 1D) receives the wakeup notification response RWN on the channel X via the antenna 12, and outputs the received wakeup notification response RWN to the host system 143B.

  The host system 143B of the wireless base station 1 (= 1D) receives the wake-up notification response RWN from the wireless communication module 141, and detects that the terminal device 10 has detected the transition of the wireless base station 1 (= 1D) to the activated state. To detect.

  Then, the host system 143B of the wireless base station 1 (= 1D) instructs the wireless communication module 141 to change the channel. The wireless communication module 141 of the wireless base station 1 (= 1D) changes the channel to the channel Y in response to an instruction from the host system 143B (step S71).

  Similarly, the wireless communication module 22 of the terminal device 10 changes the channel to channel Y (step S72).

  Thereafter, the host system 143B of the wireless base station 1 (= 1D) generates a beacon frame Beacon, outputs the beacon frame to the wireless communication module 141, and instructs the wireless communication module 141 to perform association with the terminal device 10. .

  Then, the wireless communication module 141 of the wireless base station 1 (= 1D) transmits a beacon frame Beacon on channel Y in response to an instruction from the host system 143B.

  Then, the host system 143B of the wireless base station 1 (= 1D) performs IEEE 802.11 association with the terminal device 10 via the wireless communication module 141 on the channel Y (step S73). Establish a wireless link between them.

  Thereafter, the host system 143B of the wireless base station 1 (= 1D) performs wireless communication with the terminal device 10 through the channel Y via the wireless communication module 141 (step S74).

  As a result, a series of operations is completed.

Thus, two wireless base stations 1 (= 1D), 2 (= 1D) within the communication range of the terminal device 10
) Exists, the radio base stations 1 (= 1D) and 2 (= 1D) receive the wake-up signal WKE from the terminal device 10 and shift from the sleep state to the activated state (see steps S63 and S65). Then, wake-up advertisements WA2 and WA1 are broadcast to the other radio base stations, respectively (see steps S66 and S67). Then, since the received signal strength RSSI_WKE1 at its own station is larger than the received signal strength RSSI_WKE2 at the wireless base station 2 (= 1D), the radio base station 1 (= 1D) maintains the activation state. Also, the radio base station 2 (= 1D) shifts to the sleep state because the received signal strength RSSI_WKE2 at its own station is smaller than the received signal strength RSSI_WKE1 at the radio base station 1 (= 1D) (see step S68).

  After that, the radio base station 1 (= 1D) that has maintained the activated state exchanges a wakeup notification WN and a wakeup notification response RWN with the terminal device 10 and IEEE802.11 with the terminal device 10. Association is established to establish a wireless link, and wireless communication is performed (see step S69 to step S74).

  In this way, the two radio base stations 1 (= 1D) and 2 (= 1D) shift to the activated state, but finally only the radio base station 1 (= 1D) maintains the activated state, and the terminal Wireless communication is performed with the device 10.

  Therefore, it is possible to suppress the waste of a plurality of radio base stations shifting to the activated state simultaneously.

  FIG. 18 is a flowchart for explaining the operation of the radio base station in the fifth embodiment.

  The flowchart shown in FIG. 18 is the same as the flowchart shown in FIG. 9 except that steps S51 to S53 are added to the flowchart shown in FIG.

  Referring to FIG. 18, when a series of operations is started, step S41 described above is executed. Then, the host system 143B of the radio base stations 1 to n (= 1D) generates the wake-up advertisement WA by the above-described method, and the generated wake-up advertisement WA is transmitted to the other via the radio communication module 141 and the antenna 12. Broadcast to the radio base station (step S51).

  Thereafter, the host system 143B of the radio base stations 1 to n (= 1D) determines whether or not the wake-up advertisement WA has been received from another radio base station (step S52).

  When it is determined in step S52 that the wakeup advertisement WA has not been received, the series of operations proceeds to step S42.

  On the other hand, when it is determined in step S52 that the wakeup advertisement WA has been received, the host systems 143B of the radio base stations 1 to n (= 1D) are based on the wakeup advertisement WA received from the other radio base stations. Whether there is a radio base station whose received signal strength is higher than that of its own station, or whether there is a radio base station whose received signal strength in the activated radio base station is larger than the reference value RSSI_std2. Further determination is made (step S53).

  In step S53, it is determined that there is no radio base station having a received signal strength greater than that of the own station and that there is no radio base station having a received signal strength greater than the reference value RSSI_std2 in the activated radio base station. When this is done, the series of operations proceeds to step S42.

  On the other hand, when it is determined in step S53 that there is a radio base station having a received signal strength greater than that of the own station, or a received radio signal strength at the activated radio base station is greater than the reference value RSSI_std2. When it is determined that it exists, the series of operations proceeds to step S44.

  And after step S42-step S45 or step S44 mentioned above is performed, a series of operation | movement is complete | finished.

  As described above, when the radio base station 1D does not receive the wakeup advertisement WA, the radio base station 1D transmits the wakeup notification WN to the terminal device 10, establishes a radio link with the terminal device 10, or shifts to the sleep state. The process is executed (see “NO” in step S52, S42 to S45). In this case, there is no radio base station that has transmitted the wake-up signal WKE other than the radio base station 1D. Accordingly, it is possible to suppress wasteful activation of a plurality of radio base stations at the same time.

  Further, when the radio base station 1D receives the wakeup advertisement WA, the radio base station 1D is activated based on the received wakeup advertisement WA and the first condition that there is no radio base station having a received signal strength higher than that of the own station. When it is determined that both the second condition in which no radio base station has a received signal strength at the radio base station that is in a state greater than the reference value RSSI_std2 satisfies the above-described first process (step S52). “YES”, S53 “NO”, S42 to S45). In this case, only the radio base station 1D maintains the activated state, and the other radio base stations shift to the sleep state without transmitting the wakeup notification WN (see step S44). Accordingly, it is possible to suppress wasteful activation of a plurality of radio base stations at the same time.

  Furthermore, when the radio base station 1D receives the wake-up advertisement WA and determines that the at least one of the first and second conditions is not satisfied based on the received wake-up advertisement WA, the radio base station 1D notifies the wake-up advertisement WA. The second process of shifting to the sleep state without transmitting the WN to the terminal device 10 is executed (see “YES” in step S52, “YES” in S53, and S44). In this case, wireless base stations other than the wireless base station 1D maintain the activated state. Accordingly, it is possible to suppress wasteful activation of a plurality of radio base stations at the same time.

  Note that when it is determined in step S52 that the wake-up advertisement WA has not been received, the series of operations proceeds to step S42 because the wireless base station to which the terminal apparatus 10 can be connected is only its own station.

  In step S53, there is no radio base station having a received signal strength greater than that of the own station, and no radio base station having a received signal strength greater than the reference value RSSI_std2 in the activated radio base station. When the determination is made, the series of operations proceeds to step S42 because the local station is closest to the terminal device 10 and the terminal device 10 cannot be connected to another active radio base station. It is.

  Further, when it is determined in step S53 that there is a radio base station having a received signal strength greater than that of the own station, the series of operations proceeds to step S44 because the terminal device 10 is different from the own station. This is because the station can be stably connected.

Furthermore, when it is determined in step S53 that there is a radio base station whose received signal strength in the activated radio base station is greater than the reference value RSSI_std2, the series of operations proceeds to step S44. 10 is a wake-up notification WN and a wake-up notification response RW when connected to another radio base station that has been activated rather than its own station.
This is because there is no need to exchange N (see FIG. 7), and the wireless base station can be connected in a short time.

  As described above, in the fifth embodiment, a plurality of radio base stations that have received the wake-up signal WKE from the terminal device 10 and shifted to the activated state mutually exchange the wake-up advertisement WA, thereby finally The number of radio base stations that maintain the activated state is smaller than the plurality of radio base stations that have been activated by the wake-up signal WKE (see step S41 illustrated in FIG. 18).

  Therefore, it is possible to suppress the waste of a plurality of radio base stations shifting to the activated state simultaneously.

In the fifth embodiment, each of the radio base stations 1 to n (= 1D) uses the activation probability Z ₁ , activation probability Z _2, or activation probability Z described above to further change from the sleep state to the activation state. You may make it transfer. In this case, any one of the signal generator 133 shown in FIG. 10, the signal generator 133A shown in FIG. 13, and the signal generator 133B shown in FIG. 15 is added to the wakeup device 13D. Then, the operation of the radio base station 1D is executed according to a flowchart in which step S41 of the flowchart shown in FIG. 18 is replaced with steps S41A, S41B, S41C, S41D, and S41E shown in FIG.

The wireless base stations 1 to n (= 1D) are shifted from the sleep state to the active state by further using any _{one of} the activation probabilities Z ₁ , Z ₂ , and Z, so that the above-described Embodiment 2 to Embodiment 5 The number of radio base stations activated simultaneously is further reduced than the case. Therefore, it is possible to further suppress the waste of simultaneous activation of a plurality of radio base stations.

  In the fifth embodiment, the wakeup signal receiver 131D constitutes “reception means” as in the third embodiment.

  Furthermore, in the fifth embodiment, the wakeup determination unit 132 that determines whether or not the wakeup ID matches the ID of the radio base station 1D constitutes “determination means”.

  Furthermore, in the fifth embodiment, when it is determined that the wakeup ID matches the ID of the radio base station 1D, the wakeup determination unit 132 that generates an activation signal and outputs the activation signal to the host system 143B includes “activation means”. Configure.

  Furthermore, in the fifth embodiment, the host system 143B is activated in response to the activation signal from the wakeup determination unit 132, and thus constitutes “communication means”.

In the second embodiment described above, when the wake-up ID is determined to match the ID of the radio base station 1A, it has been described that activates the wireless base station starts a probability Z _1. In the third embodiment described above, when the wake-up ID is determined to match the ID of the radio base station 1B, it has been described that activates the wireless base station starts a probability Z _2. Furthermore, in Embodiment 4 described above, when it is determined that the wake-up ID matches the ID of the radio base station 1C, the radio base station is determined with the activation probability Z (= γZ ₁ + (1−γ) Z ₂ ). Explained to start.

Therefore, the radio base station according to the embodiment of the present invention includes a receiving unit that receives a wake-up signal for activating a radio base station in the sleep state from the terminal device, and a wake-up signal received by the receiving unit A determination unit that determines whether or not to indicate activation of a radio base station, and a terminal device within a communication range of the terminal device when the determination unit determines that the wake-up signal indicates activation of the radio base station An activation unit that generates an activation signal with an activation probability indicating a percentage of the radio base stations to be activated among a plurality of radio base stations existing around the communication base, and a communication unit that activates according to the activation signal generated by the activation unit As long as it has.

  The reason is as follows. Since the activation probability is a value smaller than “1”, when the radio base station is activated with the activation probability, when it is determined that the wake-up signal indicates that the radio base station is activated, the radio is immediately transmitted. This is because the number of radio base stations to be activated is reduced compared to the case of activating the base station, and wasteful activation of a plurality of radio base stations can be suppressed.

  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, 1A, 1B, 1C, 1D wireless base station, 10 terminal device, 100 wireless communication system, 11, 12, 21 antenna, 13, 13A, 13B, 13C, 13D wake-up device, 14, 14A, 14B main Device, 15 power supply, 22,141 wireless communication module, 23, 143, 143A host system, 131, 131A, 131D
Wakeup signal receiver, 132 Wakeup determiner, 133, 133A, 133B signal generator, 142 wired communication module, 231 wakeup signal generator.

Claims (7)

Receiving means for receiving from a terminal device a wake-up signal for activating a wireless base station in a sleep state;
Determining means for determining whether or not the wake-up signal received by the receiving means indicates to activate the radio base station;
When the determination means determines that the wake-up signal indicates that the radio base station is to be activated, it activates among a plurality of radio base stations existing around the terminal device in the communication range of the terminal device An activation means for generating an activation signal with an activation probability indicating a ratio of radio base stations;
A radio base station comprising communication means that is activated in response to an activation signal generated by the activation means. Further comprising estimation means for estimating the number of the plurality of radio base stations,
The activation means determines the activation probability by dividing a constant for adjusting the number of radio base stations to be activated among the plurality of radio base stations by the estimated number of radio base stations, and a random number When the generated random number is less than or equal to the activation probability, the activation signal is output to the communication means, and when the generated random number is greater than the activation probability, the activation signal is transmitted to the communication means. It stops outputting radio base station according to claim 1. The receiving means further detects a received signal strength when the wakeup signal is received,
When the determination means determines that the wake-up signal indicates that the radio base station is to be activated by the determination means, the detected reception signal strength is a reference having a strength greater than a minimum received signal strength. When greater than the value, when the activation probability, which is the ratio of activating the radio base station, is set to 1, the detected received signal strength is greater than or equal to the minimum received signal strength and less than or equal to the reference value The activation probability is set to a value obtained by dividing the detected received signal strength by the reference value, and the activation probability is set to zero when the detected received signal strength is smaller than the minimum received signal strength. The activation probability is determined by generating a random number, and when the generated random number is equal to or less than the activation probability, the activation signal is output to the communication means, When the random number without is greater than the activation probability, and stops the output to the communication means of the activation signal, the radio base station according to claim 1. The radio base station according to claim 3 , wherein the activation unit determines the activation probability by decreasing the reference value as the number of receptions of the wakeup signal increases. Further comprising estimation means for estimating the number of the plurality of radio base stations,
The receiving means further detects a received signal strength when the wakeup signal is received,
When the determination means determines that the wake-up signal indicates that the radio base station is to be activated by the determination means, the detected reception signal strength is a reference having a strength greater than a minimum received signal strength. When greater than the value, when the activation probability, which is the ratio of activating the radio base station, is set to 1, the detected received signal strength is greater than or equal to the minimum received signal strength and less than or equal to the reference value The activation probability is set to a value obtained by dividing the detected received signal strength by the reference value, and the activation probability is set to zero when the detected received signal strength is smaller than the minimum received signal strength. To determine a first activation probability, and a constant for adjusting the number of radio base stations to be activated among the plurality of radio base stations is determined according to the estimated number of radio base stations. To determine a second activation probability, determine a weighted sum of the first activation probability and the second activation probability as a total activation probability, generate a random number, and generate the random number when it is overall activation probability below and outputs the activation signal to the communication unit, when the generated random number is greater than the total activation probability, and stops the output to the communication means of the activation signal, according to claim 1 The radio base station described in 1. A first antenna connected to the receiving means;
Further comprising a second antenna connected to the wireless communication means for performing wireless communication according to an instruction from the communication unit, the radio base station according to any one of claims 1 to 5. When the communication means is in an activated state and receives the activation signal from the activation means, the communication means transmits an active notification indicating that the radio base station is in an activated state to the terminal apparatus, and wirelessly communicates with the terminal apparatus. The radio base station according to claim 6 , wherein a link is established.

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