JP2012095032A - Transmission method of magic packet frame and radio terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption of a wireless local area network (LAN) adapter that operates in a Wake on Lan (WOL) standby state.SOLUTION: A wireless LAN adapters of stations (STAs) 21a to 21c can operate in an expansion PS mode that transitions from a doze state to an awake state in wake-up intervals Tw1 and Tw2 longer than a DTIM interval Td. The wireless LAN adapters notifies an access point (AP) of the wake-up interval before the STA proceeds to the WOL standby state. The AP transmits a magic packet frame stored in a buffer at a timing when the wireless LAN adapter transitions to the awake state. The wireless LAN adapter can reduce the power consumption of the wireless LAN adapter in comparison to a case of the transition by the DTIM interval.

Description

  The present invention relates to a technique for reducing power consumption of a wireless LAN adapter mounted on a wireless terminal device, and more particularly, in a wake-on-run (WOL) standby state until a wireless terminal device receives a magic packet. The present invention relates to a technique for reducing the power consumption of the wireless LAN adapter.

  Wireless terminal devices (hereinafter referred to as STA: Station) such as notebook personal computers (notebook PCs) and tablet computers operate in a mobile environment using a battery as a power source and adopt various power saving methods. . Recent STAs are equipped with a function called WOL (Wake On LAN) that is activated by receiving a magic packet from a distance through a network when the power is off or in a power saving state. In this specification, the operating state of a STA that is transitioning to a power saving state while waiting for a magic packet is referred to as a WOL standby state, and when a STA receives a magic packet and starts up is referred to as WOL activation.

  In order for the STA to start WOL, it is necessary to supply power to the wireless LAN card when receiving a magic packet from a wireless base station (hereinafter referred to as an access point (AP)). In the IEEE 802.11 related standard (hereinafter referred to as the 802.11 standard), a power management function is defined in order to suppress battery consumption of the wireless LAN adapter. The operation mode of the wireless LAN adapter related to power management includes an active mode and a power save mode (PS mode). The wireless LAN adapter can be operated in an wake state in which power is completely supplied to the wireless LAN card so that transmission / reception can be performed, and a doze state or sleep state in which operation can be performed with a minimum amount of power and transmission / reception is impossible. .

  The wireless LAN adapter in the active mode is always in the wake state. The wireless LAN adapter in the PS mode periodically transitions from the doze state to the awake state according to a listen interval that can be allowed by the AP, and can transmit and receive only when in the awake state. The wireless LAN adapter operates in the PS mode when the frame is not transmitted / received as in the case where the STA is in the WOL standby state. The STA in the WOL standby state stops the CPU and cannot recognize the IP address, so a broadcast frame is used to transmit a magic packet used for WOL. Hereinafter, a broadcast frame that transmits a magic packet is referred to as a magic packet frame.

  According to the 802.11 standard, when any wireless LAN adapter belonging to a basic service unit (BSS) is operating in the PS mode when the AP receives a broadcast frame, the broadcast is performed. • Do not send the frame immediately but store it in the buffer. The AP transmits the broadcast frame stored in the buffer to all the wireless LAN adapters connected immediately after transmitting the beacon frame including an information element called DTIM (Delivery Traffic Indication Message). Hereinafter, a beacon frame including DTIM is referred to as a DTIM frame, and a transmission interval of the DTIM frame is referred to as a DTIM interval.

  The AP sets the DTIM interval to be longer than a beacon interval that is an interval for transmitting a beacon frame. The STA that supports WOL sets the listen interval so that the wireless LAN adapter operating in the PS mode can listen to the DTIM frame every time while shifting to the WOL standby state. The STA in the WOL standby state stops the power supply of the processor and main devices of the main body, but the wireless LAN adapter consumes power every time it changes to the wake state at the listen interval.

  Patent Document 1 discloses a computer that starts by receiving a magic packet from an AP without handshaking. This document describes that a computer wakes up at the timing of DTIM and receives data buffered in the AP in a broadcast frame. Patent Document 2 discloses a technique for preventing delay fluctuation with respect to multicast data when the beacon intermittent number of DTIM beacons is set large.

  In the invention of this document, the DTIM beacon transmitted by the AP includes the DTIM beacon intermittent period information scheduled for broadcast transmission. Broadcast is transmitted only after transmission of a DTIM beacon scheduled for broadcast transmission, and multicast transmission is not performed. In addition, STAs operating in the PS mode and not performing multicast data communication perform reception control related to broadcast data according to the DTIM beacon intermittent period information, so that broadcast data can be transmitted even if it does not wake up every DTIM beacon period. Can receive.

JP 2005-18377 A JP 2009-5118 A

  When the PS mode wireless LAN adapter transitions to the wake state, the power consumption of the wireless LAN card increases, and moreover, power is required to transmit a frame notifying the AP to transition to the PS mode again. Power is consumed even when actual data transfer is not performed. In some cases, the user wants to acquire necessary data by sending a magic packet from his home or business trip to a STA in a WOL standby state. In the office, in order to prevent the STA from being stolen, a user who goes out usually stores the STA in a lockable cabinet or locker, and the STA in the WOL standby state may be operated by a battery.

  The power consumption of the wireless LAM adapter in the WOL standby state is particularly important for STAs operating on a battery to maintain the standby time. The 802.11 standard does not specify the maximum DTIM interval supported by the AP. Therefore, it is conceivable that the power consumption of the wireless LAN adapter in the WOL standby state can be reduced by setting the DTIM interval longer and the wireless LAN adapter setting the listen interval longer.

  However, since the AP manages the operating state of all connected STAs, and knows that any one STA is in the PS mode, it is supposed to buffer broadcast frames. The reception timing of broadcast frames received by other STAs is delayed. If the AP is unable to transmit all the previously buffered broadcast frames in one DTIM interval, it will transmit in the next DTIM interval. In real streaming reproduction of music or video transmitted in a broadcast frame, the reproduction operation may be interrupted if a data frame cannot be received at each DTIM interval.

  Further, in the 802.11 standard, the AP cannot discard the buffered frame until it is sent to the wireless LAN adapter. Therefore, when a long DTIM interval is set, a large number of data frames are stored in the buffer. Is accumulated. Therefore, if the DTIM interval is set long, the buffer overflows and the IP telephone and the above-mentioned real streaming reproduction are affected. Since the AP can limit the maximum value of the DTIM interval in order to prevent such a situation, the AP may not allow the wireless LAN adapter to set a long listen interval unconditionally.

  The wireless LAN adapter can set the listen interval to be longer than the DTIM interval. However, in this case, in order to avoid the buffer overflow until the frame is sent to the wireless LAN adapter, the AP is unconditionally long. The interval may not be allowed. Alternatively, the AP may clear the buffer after sending a broadcast frame at the timing of the DTIM interval.

  A newly manufactured AP can support a longer DTIM interval by increasing the size of the buffer, but it is a good idea to prepare an oversized buffer to buffer magic packets with a small amount of data. Absent. The longer the listen interval, the larger the size of the prepared buffer. Therefore, in a wireless LAN system in which wireless LAN adapters operating in accordance with the 802.11 standard coexist, a new mechanism is required to further reduce the power consumption of the wireless LAN adapter in the WOL standby state.

  Therefore, an object of the present invention is to provide a method for reducing the power consumption of a wireless terminal device operating in a WOL standby state. It is a further object of the present invention to provide a method for reducing the power consumption of a wireless terminal device that has entered a WOL standby state while not affecting other wireless terminal devices that operate based on the provisions of the IEEE 802.11 standard. It is to provide. A further object of the present invention is to provide a wireless terminal device, a wireless LAN adapter, a wireless base station, and a computer program that realize such a method.

  The present invention provides a method for further reducing the power consumption of a wireless LAN adapter in a WOL standby state in a wireless LAN system operating in accordance with the IEEE 802.11 standard. The IEEE 802.11 standard defines a power save mode. In the power save mode, the radio base station transmits a broadcast frame at the transmission timing of the DTIM frame.

  On the other hand, in the wireless LAN system according to the present invention, an extended power save mode is defined in which the wireless LAN adapter transitions from the doze state to the wake state at a wake-up interval longer than the DTIM interval specified by the IEEE 802.11 standard. Thus, the power consumption of the wireless LAN adapter in the WOL standby state is reduced. When the wireless terminal device shifts to the WOL standby state, the wireless LAN adapter can notify the wireless base station of shifting to the extended power save mode. Based on the notification of transition, the wireless base station measures the timing at which the wireless LAN adapter operating in the extended power save mode transitions to the wake state.

  When the wireless base station receives a magic packet frame from the backbone network and determines that a wireless LAN adapter that operates in the extended power save mode is connected to the wireless base station, the wireless base station The packet frame is stored in the first buffer. The wireless base station transmits the magic packet frame stored in the first buffer at the timing when the wireless terminal device transitions to the wake state. According to such a configuration, the wireless LAN adapter operates at a wakeup interval longer than the DTIM interval specified in the IEEE 802.11 standard while the wireless terminal device is in the WOL standby state, and operates as a magic packet.・ The frame can be received.

  The wakeup interval can be an integral multiple of the beacon frame transmitted by the radio base station. Therefore, a wireless LAN adapter operating in the extended power save mode can transition to the wake state at any beacon frame timing, and the wireless base station can calculate the same beacon frame timing. A magic packet frame can be transmitted.

  When the wireless base station receives a broadcast frame or multicast frame from the backbone network, the wireless base station determines that one of the connected wireless LAN adapters operates in the power save mode defined in the IEEE 802.11 standard. The broadcast frame or multicast frame can be stored in the second buffer without being stored in the first buffer. Therefore, even when a wireless terminal device operating in the power save mode specified in the IEEE 802.11 standard is connected to the same wireless base station, broadcast frames and multicast frames can be transferred in the power save mode. Has no effect.

  By distinguishing between the first buffer and the second buffer, each can be cleared at its own timing, and the timing for stopping the transmission of the broadcast frame and the transmission of the magic packet frame can be mutually determined. It can be decided independently. Note that the first buffer and the second buffer can also be configured by partitioning the storage area of the physically same memory.

  The wireless base station transmits the broadcast frame and the multicast frame stored in the second buffer at the timing when the wireless LAN adapter operating in the power save mode defined in the IEEE 802.11 standard transitions to the wake state. To do. Therefore, a magic packet frame can be transmitted as a broadcast frame to be transmitted immediately after a DTIM frame is transmitted to a wireless LAN adapter that operates in the power save mode defined in the IEEE 802.11 standard.

  The radio base station can receive unicast frames from the backbone network. The wireless base station can discard the unicast frame when it determines that the destination of the unicast frame is a wireless LAN adapter operating in the extended power save mode. According to such a configuration, since only the magic packet frame is stored in the first buffer, there is no possibility of overflow even if the wakeup interval becomes long.

  In addition, since the wireless terminal device cannot process a frame other than the magic packet frame during the WOL standby state, there is no problem even if the wireless base station performs such processing. The wireless base station maintains the connection of the wireless LAN adapter while the wireless LAN adapter is operating in the extended power save mode. Therefore, the wireless LAN adapter can receive the magic packet frame even if the wake-up interval becomes long or without re-association at the timing of transition to the wake state.

  A plurality of wireless terminal devices operating in the extended power save mode have different timings for transition to the wake state. The wireless base station can transmit a magic packet frame as a broadcast frame at every timing when any of the plurality of wireless LAN adapters operating in the extended power save mode is transitioning to the wake state. After transmitting the magic packet frame to all wireless LAN adapters operating in the extended power save mode, the wireless base station clears the first buffer and stops transmitting the magic packet frame. can do.

  According to the present invention, it is possible to provide a method for reducing power consumption of a wireless terminal device operating in a WOL standby state. Furthermore, the present invention provides a method for reducing the power consumption of a wireless terminal device that has entered the WOL standby state while not affecting other wireless terminal devices that operate based on the provisions of the IEEE 802.11 standard. I was able to. Further, according to the present invention, it is possible to provide a wireless terminal device, a wireless LAN adapter, a wireless base station, and a computer program that realize such a method.

It is a figure which shows the network structure of the wireless LAN system of the infrastructure mode prescribed | regulated to 802.11 standard. It is a schematic functional block diagram which shows the structure of STA. It is a schematic functional block diagram which shows the structure of the wireless LAN adapter mounted in STA. It is a schematic functional block diagram which shows the structure of AP. It is a time chart which shows operation | movement of a wireless LAN system. It is a flowchart explaining operation | movement of AP which supports extended PS mode. It is a flowchart explaining operation | movement of AP which supports extended PS mode. It is a flowchart explaining the procedure which transmits the Ethernet frame memorize | stored in the buffer. It is a figure which shows the data structure of an operation mode table. It is a figure explaining the data structure of an 802.11 MAC frame.

[Configuration of wireless LAN system]
FIG. 1 is a diagram showing a network configuration of an infrastructure mode wireless LAN system 10 defined in the 802.11 standard. FIG. 1 shows a state in which a remote computer 13 and an AP 20 are typically connected to the backbone network 11. The backbone network 11 can be configured to include wireless and wired networks such as the Internet and an intranet, and the AP 20 is connected to the backbone network 11 by Ethernet (registered trademark). Various servers such as a Web server, a mail server, a DNS server, and a database server, not shown in FIG. 1, and IP packet routing devices are connected to the backbone network 11.

  The wireless LAN system 10 includes an AP 20, STAs 21 a, 21 b, 21 c, 31 a, 31 b and a part of the backbone network 11. Each STA exists in a range where the radio waves of the AP 20 can reach, and the AP 20 and each STA constitute a BSS. The remote computer 13 can send a magic packet to the wireless LAN system through the backbone network 11 and start a specific STA operating in the WOL standby state.

  The remote computer 13 is typically a notebook PC used by any of the STAs 21a, 21b, 21c, 31a, and 31b for WOL activation of their STA at a business trip destination or at home, or the wireless LAN system 10 Or a manager computer for WOL activation of all STAs at once to update or install software.

[Configuration of STA]
FIG. 2 is a schematic functional block diagram showing the configuration of the STA 21a. The STA 21a includes a CPU 51, a memory control hub (MCH) 55, a main memory 53, a video card 57, an I / O control hub (ICH) 61, a wireless LAN adapter 59, a hard disk drive (HDD) 63, an embedded A controller (EC) 65 and a flash ROM 67 are included.

  The STA 21a conforms to the ACPI standard, and is in one of the power states of S0 state (power-on state), S3 state (suspend state), S4 state (hibernation state), and S5 state (soft-off state). Can be migrated to. The S3 state and the S4 state are called sleeping states. Since the CPU 51 does not operate in the sleeping state and the soft-off state, the STA 21a interprets the IP address of the 802.11 MAC frame received from the AP 20 with the function of the OSI reference model layer 3 (network layer) or higher stopped. It is not possible.

  The ICH 61 includes USB (Universal Serial Bus), SATA (Serial AT Attachment), SPI (Serial Peripheral Interface) bus, PCI (Peripheral Component Interconnect) bus, PCI-Express (PCIe) bus, LPC (Low Pin Count) bus, etc. It is possible to connect devices corresponding to these interfaces. The ICH 61 also has a state register for storing the current power state of the STA 21a and a power state after the change when the power state is changed, and a WOL register for setting the WOL.

  The state register is set by the BIOS. The ICH 61 notifies the wireless LAN adapter 59 when the state register is set by the BIOS to change from the S0 state to the S3 state or the S4 state. The wireless LAN adapter 59 that has received the notification can set the power management field 311 (FIG. 10) and notify the AP 20 and then can shift to the PS mode defined in the IEEE 802.11 standard. However, as will be described later, the wireless LAN adapter 59 can also set the extended PS mode field 327 (FIG. 10) and shift to the extended PS mode newly defined in the present embodiment.

  When the BIOS or OS sets the WOL register of the ICH 61 to be enabled, the STA 21a whose power state after being changed to the state register is set to the S3 state or the S4 state shifts to the WOL standby state. The state in which the WOL register is set to enable and the STA 21a has shifted to the S3 state or the S4 state corresponds to the WOL standby state. When the wireless LAN adapter 59 receives a magic packet addressed to itself in the WOL standby state, it notifies the ICH 61. Upon receiving the notification, the ICH 61 shifts the STA 21a to the power-on state through the EC 65 and starts WOL. However, the STA 21a can be configured to perform WOL activation even in the S5 state.

  The power state of the STA 21a main body and the operation mode of the wireless LAN adapter 59 do not need to be directly related to each other. When the wireless LAN adapter 59 is turned on and does not transmit / receive an 802.11 MAC frame for a predetermined time, it can shift to the PS mode by itself. Therefore, the wireless LAN adapter 59 may enter the PS mode even when the STA 21a is in the S0 state. When the STA 21a is in the sleeping state or the soft-off state, the wireless LAN adapter 59 shifts to the PS mode if the WOL register is set to enable, and shifts to the power-off state if it is set to disable.

  The flash ROM 67 stores a BIOS that conforms to the ACPI standard. The EC 65 includes a CPU, a ROM, and a RAM, and operates independently of the CPU 51 to control the power supply and temperature of the STA 21a. The power supply device 69 includes a DC / DC converter, a hardware logic circuit, a charger, a power supply switching circuit, and the like, and supplies power to the electronic devices constituting the STA 21a. When it is detected that the AC / DC adapter 71 is connected, the power supply switching circuit supplies power to the DC / DC converter and the charger from the AC / DC adapter 71 or connects the AC / DC adapter 71. When not detected, power is supplied from the battery 73 to the DC / DC converter.

  In the DC / DC converter, the system is divided so that an electronic device that supplies electric power can be selected according to the power state. The EC 65 controls the power supply device 69 so that electric power is supplied to the corresponding electronic device according to the power state of the STA 21a. In the WOL standby state, power is supplied to at least the wireless logic adapter 59, the circuit related to the WOL of the ICH 61, the hardware logic circuit that controls the EC 65 and the DC / DC converter of the power supply 69. When receiving the magic packet frame addressed to itself in the WOL standby state, the wireless LAN adapter 59 notifies the EC 65 of it. The EC 65 controls the power supply device 69 to shift the STA 21a to the S0 state. The other STAs shown in FIG. 1 have the same configuration.

[Frame structure]
FIG. 10 shows the data structure of an 802.11 MAC frame defined in the IEEE 802.11 standard. The 802.11 MAC frame 300 defines the structure of data transferred between the AP 20 and each STA. The 802.11 MAC frame 300 is composed of a frame body 305 and a MAC header. The MAC header includes a frame control field 301 and a destination address field 303. When the 48-bit destination field 303 is all 1, it indicates that the 802.11 MAC frame is a broadcast frame.

  The frame control field 301 includes a type field 307, a subtype field 309, and a power management field 311. The type field 307 indicates whether the 802.11 MAC frame is a management frame, a control frame, or a data frame. When the 802.11 MAC frame is a management frame, the subtype field 309 indicates which type of 802.11 MAC frame, such as an association request frame, a beacon frame, or an authentication request frame. A 1-bit power management field 311 indicates that when the 802.11 MAC frame transmitted by the wireless LAN adapter 59 is set to 1, the wireless LAN adapter will subsequently operate in the PS mode, and when set to 0, the active mode. Shows that it works.

  The frame body 305 of the management frame includes a beacon interval field 313, a listen interval field 315, a TIM (traffic indication map) field, and a vendor specific field 325. The beacon interval field 313 indicates the transmission time interval of the target beacon. The listen interval field 315 sets the listen interval in the 802.11 MAC frame by the wireless LAN adapter 59 operating in the PS mode between the SME (Station Management Entity) and the MLME (MAC Layer Management Entity).

  The listen interval indicates the number of beacon intervals from when the wireless LAN adapter 59 operating in the PS mode transitions to the doze state to transition to the wake state. The wireless LAN adapter 59 can operate at a listen interval within a range allowed by the AP in the PS mode. The TIM field includes a DTIM count field 317, a DTIM period field 319, a bit map control field 321 and a PVB field 323, and information regarding power management is set in a beacon frame transmitted by the AP.

  The DTIM count field 317 indicates the number of beacon frames transmitted before the next DTIM frame, and when 0 indicates that the current beacon frame is a DTIM frame. The DTIM period field 319 is set with a value representing the periodic interval at which the DTIM frame is transmitted by the number of beacon frames. A value representing the interval at which the DTIM frame is transmitted by the number of beacon intervals corresponds to the DTIM interval, which is an integral multiple of the beacon interval.

  The wireless LAN adapter 59 that has received the beacon frame can acquire the timing at which the DTIM frame is transmitted after the next beacon frame by analyzing the DTIM count field 317. When one or more multicast or broadcast frames are stored in the buffer, the AP sets the bit map control field 321 to 1 in a beacon frame in which the DTIM count field is 0, that is, a DTIM frame.

  The AP transmits a multicast frame or a broadcast frame stored in the buffer immediately after transmitting the DTIM frame. When the wireless LAN adapter 59 operating in the PS mode is set to 1 in the bit map control field 321 in the DTIM frame, the wireless LAN adapter 59 is in a wake-up state for a sufficient time to receive a multicast frame or a broadcast frame. To maintain. The PVB field 323 indicates whether there is a frame stored in the buffer for each STA and it is ready for transmission.

  Information that is not defined in the IEEE 802.11 standard can be set in the vendor specific field 325. The vendor specific field 325 includes an extended PS mode field 327 and an wake interval field 329 defined by the mobile phone of the present embodiment. In the 802.11 MAC frame, the wireless LAN adapter 59 sets information indicating that the extended PS mode is entered in the extended PS mode field 327, and sets the outage interval of the extended PS mode in the outwake interval field 329. The wake interval is finally determined by negotiation with the AP.

[Wireless LAN adapter]
FIG. 3 is a schematic functional block diagram showing the configuration of the wireless LAN adapter 59 mounted on the STA 21a. The wireless LAN adapter 59 includes a physical layer unit 111 that performs layer 1 (physical layer) processing of the OSI reference model and a data link layer unit that performs layer 2 processing. The PCIe interface 101 is connected to the PCIe port of the ICH 61 by a lane composed of a total of four signal lines and other signal lines, and controls the transfer of IP packets between the CPU 51 and the data link layer unit 105. . The wireless LAN adapter 59 can be configured by another interface such as a USB instead of the PCIe interface 101. The memory 103 includes a transmission / reception buffer for storing IP packets.

  The data link layer unit 105 sends the 802.11 MAC frame generated by adding the MAC header to the IP packet received from layer 3 of the OSI reference model to the physical layer unit 107, and receives the 802. The IP packet generated by removing the MAC header from the 11 MAC frame is sent to layer 3. The data link layer unit 105 includes a wireless channel access function based on CSMA / CA and a management function related to connection between the AP 20 and the wireless LAN adapter 59.

  The data link layer unit 105 controls the transmission timing of the beacon frame, executes power management of the wireless LAN adapter 59, or executes association with the AP 20. The data link layer unit 105 controls the operation of the power supply circuit 113. The power supply circuit 113 supplies the power received from the power supply device 69 to the internal device of the wireless LAN adapter 59.

  When the STA 21a is in the S0 state, the data link layer unit 105 transmits a frame in which the power management field 311 is set to the AP when it determines that there is no transmission or reception 802.11 MAC frame for a certain period of time. After the notification, the PS mode specified by the 802.11 standard is entered, and the power supply circuit 113 is instructed to operate the wireless LAN adapter 59 in the PS mode. In the PS mode, the power supply circuit 113 periodically changes the wireless LAN adapter 59 from the doze state to the wake state at the listen interval negotiated with the AP 20.

  The data link layer unit 105 supports WOL. The data link layer unit 105 includes an extended PS processing unit 107 that performs processing for the wireless LAN adapter 59 to operate in the extended PS mode when the STA 21a operates in the WOL standby state. The extended PS mode is an operation mode in which the wireless LAN adapter 59 periodically changes from the doze state to the wake state at an interval longer than the PS mode defined by the 802.11 standard. The user can set in advance in the extended PS processing unit 107 whether the wireless LAN adapter 59 operates in the PS mode or the extended PS mode when in the WOL standby state.

  When the extended PS processing unit 107 in which the extended PS mode is enabled receives a notification from the ICH 61 that the STA 21a enters the WOL standby state, the 802.11 MAC frame in which the extended PS mode field 327 and the wake interval field 329 are set. Is transmitted to the AP 20 to shift to the extended PS mode. When the extended PS processing unit 107 receives the 802.11 MAC frame from the AP 20 and recognizes the determined wake-up interval, the extended PS processing unit 107 instructs the power supply circuit 113 to shift the wireless LAN adapter 59 to the doze state. The wakeup interval will be described in detail later. The extended PS processing unit 107 instructs the power supply circuit 113 to shift the wireless LAN adapter 59 to the wake state when the number of beacon intervals based on the beacon frames thereafter reaches the wake-up interval.

  While the wireless LAN adapter 59 is connected to the AP 20, the extended PS processor 107 waits until the STA 21 a starts WOL, starts normally, or resumes from the suspended state until it shifts to the S0 state. The power supply circuit 113 is controlled at a periodic wakeup interval. While operating in the extended PS mode, the extended PS processing unit 107 can determine the wake-up interval by transmitting an 802.11 MAC frame to the AP 20 each time before transitioning from the wake state to the doze state.

  The data link layer unit 105 includes a nonvolatile memory 109 that stores a MAC address that is a unique identifier of the wireless LAN adapter 59. The magic packet for WOL activation is the MAC address of the STA that wants to activate WOL following the destination IP address in which all bits are set to 1 so that the remote computer 13 indicates a packet of a broadcast frame. Is repeated 16 times.

  The AP 20 transmits the magic packet frame to all STAs belonging to the BSS. When the data link layer unit 105 receives the magic packet frame from the AP 20 when the wireless LAN adapter 59 operating in the extended PS mode transitions to the wake-up state, the data link layer unit 105 checks the frame body field 305 to confirm the destination. It is determined whether or not there is a MAC address that matches the MAC address stored in the non-volatile memory 109. If they match, the ICH 61 is notified, and if they do not match, the 802.11 MAC frame is discarded.

  The extended PS processing unit 107 can be configured by a processor, a memory, and a computer program. When the STA 21a is in a state other than the WOL standby state, the wireless LAN adapter 59 does not operate in the extended PS mode but operates in the active mode or the PS mode. The physical layer unit 111 modulates and transmits a high-frequency signal using the encoded 802.11 MAC frame, demodulates the received high-frequency signal, generates an encoded 802.11 MAC frame, and generates a data link layer unit. Sent to 105.

[Configuration of AP]
FIG. 4 is a schematic functional block diagram showing the configuration of the AP 20. The Ethernet interface 151 is connected to the backbone network 11 via Ethernet (registered trademark), and controls bidirectional IP packet transfer. The control unit 153 includes a CPU, a memory used for program execution, and a flash memory for storing the program, and these constitute an operation mode table 157, a counter 159, a buffer control unit 161, and a data control unit 163. .

  The buffer 165 is used by the AP 20 to transfer an 802.11 MAC frame defined in the IEEE 802.11 standard to the wireless LAN adapter 59 operating in the PS mode. The extension buffer 167 is used by the AP 20 to transfer a magic packet frame to the wireless LAN adapter 59 operating in the extended PS mode. The buffer 165 and the expansion buffer 167 may be physically different memories, but can also be used by partitioning the area using the same memory.

  The data control unit 163 associates with the wireless LAN adapter 59 belonging to the BSS, and registers or updates the operation state of the wireless LAN adapter 59 in the operation mode table 157 every time the operation mode of the wireless LAN adapter 59 is changed. If there is a disconnection request from the wireless LAN adapter 59, the registration is deleted. FIG. 9 shows the data structure of the operation mode table. In FIG. 9, the MAC address of the wireless LAN adapter 59 currently connected to the AP 20 is registered in the MAC address field. An AID assigned when the AP 20 connects the wireless LAN adapter 59 is registered in an AID (Association ID) field. In the PS mode field, 1 is set for the wireless LAN adapter 59 currently operating in the PS mode, and 0 is set for the wireless LAN adapter 59 operating in the active mode.

  In the listen interval field, the listen interval negotiated between the wireless LAN adapter 59 and the AP 20 before entering the PS mode is registered. The extended PS mode field is set to 1 for the wireless LAN adapter 59 currently operating in the extended PS mode, and is set to 0 for the wireless LAN adapter 59 operating in the active mode or the PS mode. In the wake-up interval field, a wake-up interval in the extended PS mode that is negotiated between the wireless LAN adapter 59 and the AP 20 before entering the extended PS mode is registered. In the count value field, the number of beacon frames until the wireless LAN adapter 59 operating in the extended PS mode wakes up next is recorded.

  The data control unit 163 manages the operation mode of all STAs connected to the AP 20, determines the transmission timing of the Ethernet frame received from the backbone network 11, and sends it to the wireless LAN communication unit 155. The transmission timing differs depending on whether the frame is stored in either the buffer 165 or the buffer 167 or not. The data control unit 163 determines the transmission timing and sends the 802.11 MAC frame to the wireless LAN communication unit 155. The data control unit 163 also sends the 802.11 MAC frame received through the wireless LAN communication unit 155 to the backbone network 11 through the Ethernet interface 151.

  The counter 159 counts the beacon frame transmission timing in synchronization with the wireless LAN communication unit 155. The counter 159 decrements the current count value in the count value field in the operation mode table 157 every beacon interval, and registers the wake-up interval again after becoming 0. The buffer control unit 161 stores the Ethernet frame received from the backbone network 11 in the buffer 165 or the expansion buffer 167 with reference to the operation mode table 157, or wireless LAN communication via the direct data control unit 163 Or sent to part 155.

  The buffer control unit 161 refers to the operation mode table 157 when receiving a broadcast frame, a multicast frame, and a unicast frame from the backbone network 11. When it is determined that any one of the wireless LAN adapters 59 is operating in the PS mode, the broadcast frame and the multicast frame are stored in the buffer 165, and the frame is stored in the buffer 165 in the data control unit 163. Notify that

  When a unicast frame destined for the wireless LAN adapter 59 operating in the PS mode is received, the frame is stored in the buffer 165, and the unicast frame destined for the wireless LAN adapter operating in the active mode is stored. When it is received, it is immediately sent to the data control unit 163. At this time, the buffer control unit 161 does not make the condition for storing in the buffer 165 whether or not the wireless LAN adapter 59 operating in the extended PS mode is connected.

  A broadcast frame refers to a frame destined for all wireless LAN adapters 59 in the broadcast domain, a multicast frame refers to a frame destined for a plurality of wireless LAN adapters 59, and a unicast frame refers to 1 A frame destined for one wireless LAN adapter 59. The magic packet frame is stored in the buffer 165 as a broadcast frame. The data control unit 163 transmits the magic packet frame 163 to the wireless LAN adapter 59 operating in the PS mode immediately after transmitting the DTIM frame.

  The buffer control unit 161 refers to the operation mode table 157 when receiving a magic packet frame from the backbone network 11. When it is determined that the STA operating in the extended PS mode is connected, the magic packet frame is stored in the extended buffer 167. When the buffer control unit 161 determines that the wireless LAN adapter 59 operating in the PS mode and the wireless LAN adapter 59 operating in the extended PS mode are connected when the magic packet frame is received, The magic packet frame is stored in the buffer 165 and the buffer 167.

  When receiving a unicast frame destined for the wireless LAN adapter 59 operating in the extended PS mode, the buffer control unit 161 discards it without storing it in any buffer. The buffer control unit 161 does not store broadcast frames other than unicast frames, multicast frames, and magic packet frames in the extension buffer 167. When it is determined that no wireless LAN adapter 59 is operating in the PS mode or the extended PS mode, the buffer control unit 161 immediately sends the Ethernet frame received from the backbone network 11 to the data control unit 163.

  The wireless LAN communication unit 155 performs data link layer and physical layer processing and wirelessly transmits and receives 802.11 MAC frames to and from the wireless LAN adapter 59. The data link layer unit deletes the Ethernet header from the Ethernet frame received from the data control unit 163 and adds a MAC header, or removes the MAC header from the 802.11 MAC frame received from the wireless LAN adapter 59. And add an Ethernet header. AP 20 is not allowed to operate in PS mode and always operates in active mode.

  Note that FIGS. 1 to 4 simply describe the main hardware configuration and connection relation related to the present embodiment in order to explain the present embodiment. Many devices are used for the wireless LAN adapter 59 and the AP 20 other than those mentioned in the above description. However, they are well known to those skilled in the art and will not be described in detail here. A person skilled in the art also arbitrarily selects a plurality of blocks described in the figure as one integrated circuit or device, or conversely, a block is divided into a plurality of integrated circuits or devices. Is included in the scope of the present invention.

[Operation of wireless LAN system]
Next, the operation of the wireless LAN system 10 will be described. FIG. 5 is a time chart showing an example of the operation of the wireless LAN system 10. 6 and 7 are flowcharts for explaining the operation of the AP 20 that supports the extended PS mode. All the wireless LAN adapters 59 operate based on the 802.11 standard, but the wireless LAN adapter 59 mounted on the STAs 21a to 21c must operate in the extended PS mode according to the present embodiment while in the WOL standby state. Can do.

  In FIG. 5, the AP 20 transmits a beacon frame at the beacon interval T. Beacon frames 2, 5, ... (n-3), n correspond to DTIM frames. In the following description, when it is necessary to describe the wireless LAN adapter in association with the STA, for example, the wireless LAN adapter 59 mounted on the STA 21a is represented as a wireless LAN adapter 59 (21a), and other wireless LAN adapters are described. Is also expressed in the same way. The wireless LAN adapter 59 (31a) operates in the active mode, and can send and receive 802.11 MAC frames at any time. The wireless LAN adapter 59 (31b) operates in the PS mode, and periodically transitions from the doze state to the away state at the listen interval Td. The listen interval Td coincides with the DTIM interval, and the wireless LAN adapter 59 (31b) can listen to all DTIM frames. The wireless LAN adapters 59 (21a) to 59 (21c) operate in the extended PS mode.

  The wireless LAN adapters 59 (21a) to 59 (21c) shift to the extended PS mode at times t6, t7, and t5, respectively. In the extended PS mode, the wireless LAN adapter periodically transitions from the doze state to the wake state at intervals that are integral multiples of the beacon interval T. The interval at which the wireless LAN adapter operating in the extended PS mode transitions from the doze state to the wake state is referred to as a wake-up interval in order to distinguish it from the listen interval. The wakeup interval is set longer than the listen interval between the AP 20 and the wireless LAN adapters 59 (21a) to 59 (21c).

  Here, the wireless LAN adapters 59 (21a) and 59 (21b) transition to the wake-up state at the wake-up interval Tw1, and the wireless LAN adapter 59 (21c) transitions to the wake-up state at the wake-up interval Tw2. FIG. 5 shows a state in which a frame stored in the buffer 165 until that point is transmitted immediately after each DTIM frame, and is received by the wireless LAN adapter 59 that has transitioned to the wake state at that timing. Then, the buffer control unit 161 clears the buffer 165 after transmitting the frame. Note that the wireless LAN adapters 59 (21a) to 59 (21c) operating in the extended PS mode may transition to the wake state at the transmission timing of the DTIM frame and receive the frame stored in the buffer 165. That is not the operation intended by the present invention.

  Also, in FIG. 5, the magic packet frame is stored in the expansion buffer 167 at time t8 after all the wireless LAN adapters 59 (21a) to 59 (21c) operate in the extended PS mode, and the AP 20 transmits the beacon frame ( n-2) and magic packet frame are transmitted at the timing of (n-1). Then, the wireless LAN adapters 59 (21a) and 59 (21c) transition to the wake state at the timing of the beacon frame (n-2), and the wireless LAN adapter 59 (21b) is at the timing of the beacon frame (n-1). Then, a transition is made to the wake state, and a magic packet frame is received.

  In block 201 of FIG. 6, the AP 20 operates to transmit a beacon frame at the beacon interval T. In block 203, at time t1, the wireless LAN adapter 59 (31a) receives authentication at the MAC layer level by the AP 20, and further performs association to connect to the AP 20. Thereafter, the wireless LAN adapter 59 (31a) operates in the active mode and maintains the wake-up state. The wireless LAN adapter 59 (31a) can transmit and receive the 802.11 MAC frame with the AP 20 at an arbitrary timing.

  The data control unit 163 of the AP 20 registers the wireless LAN adapter 59 (31a) of the STA 31a in the operation mode table 157 as shown in FIG. In block 205, the wireless LAN adapter 59 (31b) is similarly connected to the AP 20. At time t11, the wireless LAN adapter 59 (31b) sends an 802.11 MAC frame in which the power management field 311 is set to 1 to negotiate with the AP 20 to shift to the WOL standby state, and then negotiates with the active AP. Transition from mode to 802.11 standard PS mode.

  Between the wireless LAN adapter 59 (31b) and the AP 20, the instructions MLME-POWERMGT.request and MLME-POWERMGT.confirm are used in order to determine the listen interval when entering the PS mode. MLME-POWERMGT.request includes an information element called ListenInterval indicating a listen interval and an information element called ReceiveDTIMs indicating whether or not all DTIMs are received. The wireless LAN adapter 59 (31b) sets ReceiveDTIMs to true when the wireless LAN adapter 59 (31b) transitions to the wake state at the timing of all DTIM frames.

  As shown in FIG. 5, here, the listen interval is set to 3, and the wireless LAN adapter 59 (31 b) sets the beacon frames 2, 5,. Transition to the wake state and listen to the beacon frame. The AP 20 transmits the multicast frame and the broadcast frame stored in the buffer 165 at that time immediately after transmitting the DTIM frame.

  The AP 20 transmits the frame that has been stored in the buffer 165 until immediately after the transmission of the DTIM frame 2, then clears the buffer 165, and further receives the Ethernet frame received from the backbone network 11 until the DTIM frame 5. After storing in the buffer 165, the buffer 165 is cleared immediately after transmission of the DTIM frame 5.

  If the AP 20 cannot transmit the frames stored in all the buffers 165 at the timing of the DTIM frame 2, the AP 20 transmits the frame remaining immediately after the transmission of the DTIM frame 5. When the wireless LAN adapter 59 (31b) refers to the PVB field 323 of the DTIM frame and finds that the unicast frame addressed to itself is stored in the buffer 165, the wireless LAN adapter 59 (31b) transmits a control frame called PS-Poll to the AP 20. Can be received.

  The wireless LAN adapters 59 (21 a) to 59 (21 c) are set so that the WOL register of the ICH 61 is enabled and the extended PS processing unit 107 is enabled in the extended PS mode. In block 207, the STA 21a operating in the S0 state connects to the AP 20 at time t2. The wireless LAN adapter 59 (21a) immediately after connection is operating in the active mode. In block 209, the STA 21a shifts to the S3 state or the S4 state due to a user operation or a predetermined idle time elapses, thereby shifting to the WOL standby state. At this time, the ICH 61 notifies the wireless LAN adapter 59 (21a) that the STA 21a shifts to the WOL standby state.

  The data link layer unit 105 of the wireless LAN adapter 59 (21a) transmits the 802.11 MAC frame to the AP 20 in order to shift to the extended PS mode at time t6 immediately after receiving the beacon frame 3. The AP 20 refers to the extended PS mode field 327 regardless of the setting contents of the power management field 311 and determines that the wireless LAN adapter 59 (21a) is not operating in the PS mode. However, the AP 20 recognizes that the wireless LAN adapter 59 (21a) operates in the active mode and does not perform frame buffering or transmission timing control based on the provisions of the 802.11 standard. Special control for extended PS mode.

  The wireless LAN adapter 59 (21a) sets a bit for entering the extended PS mode in the extended PS mode field 327 of the 802.11 MAC frame, and sets the wakeup interval Tw1 in the wake interval field 329. The wakeup interval Tw1 can be, for example, 100 to 200 times the beacon interval. The wake-up interval Tw1 corresponds to a time that is an integral multiple of the beacon interval T from the next received beacon frame 4 to the beacon frame (n-2) that transitions to the wake state, and is shown in FIG. As you can see, it is 200.

  When the AP 20 receives the magic packet frame from the backbone network 11 and there is a wireless LAN adapter 59 that operates in the extended PS mode, the AP 20 temporarily stores it in the extension buffer 167, but the amount of data is not large. Therefore, even if the wakeup interval is lengthened, the problem of buffer overflow hardly occurs. The AP 20 transmits the frame stored in the buffer 165 at a DTIM interval independent of the transmission of the magic packet frame stored in the expansion buffer 167. Therefore, even if the wakeup interval is increased, the 802.11 standard is used. This does not affect other wireless LAN adapters 59 that receive broadcast frames.

  The wireless LAN adapter 59 (21a) determines the wake-up interval by negotiating with the AP 20 within the allowable range from when the remote computer 13 sends a magic packet until the STA 21a actually starts WOL activation. be able to. Alternatively, the AP 20 can request the wireless LAN adapter 59 (21a) to set the wakeup interval to a preset fixed value. The data control unit 163 of the AP 20 sets the determined wakeup interval Tw1 in the 802.11 MAC frame and transmits it to the wireless LAN adapter 59 (21a).

  The data control unit 163 of the AP 20 that has transmitted the 802.11 MAC frame registers the MAC address of the wireless LAN adapter 59 (21a) read from the 802.11 MAC frame and the AID determined at the time of association in the operation mode table 157. When the AP 20 is set to cancel the association when there is no traffic for a predetermined time with respect to the wireless LAN adapter 59 that performs data transfer based on the 802.11 standard, the AP 20 Do not break the association.

  Subsequently, the data control unit 163 registers the wakeup interval Tw1 and the current count value in the wakeup interval field and the count value field for the wireless LAN adapter 59 (21a) in the operation mode table 157. At the time of registration, the wakeup interval Tw1 matches the current count value, but the current counter 159 is decremented by 1 at the timing of the subsequent beacon interval.

  In block 211, the data link layer unit 105 of the wireless LAN adapter 59 (21a) that has received the 802.11 MAC frame controls the power supply circuit 113 to operate the wireless LAN adapter 59 in the extended PS mode. The wireless LAN adapter 59 (21a) periodically transitions from the doze state to the wake state at the wake-up interval Tw1. When the second and subsequent times transition from the wake state to the doze state, the wireless LAN adapter 59 (21a) transmits the 802.11 MAC frame and executes the same procedure. In block 213, the wireless LAN adapter 59 (21b) shifts to the extended PS mode at time t7 and the wireless LAN adapter 59 (21c) shifts to the extended PS mode at time t5 in the same procedure.

  In block 215, AP 20 receives an Ethernet frame from backbone network 11. In block 217, the buffer control unit 161 performs buffering processing according to the operation mode of the wireless LAN adapter 59 connected to the Ethernet frame type. The procedure of block 217 will be described with reference to the flowchart of FIG. In block 217-1, the buffer control unit 161 checks whether the received Ethernet frame is a broadcast frame based on the destination MAC address.

  In the case of a broadcast frame, in block 217-3, the buffer controller 161 refers to the PS mode field of the operation mode table 157 and operates in the PS mode in the currently connected wireless LAN adapter 59. It is checked whether or not the wireless LAN adapter 59 is connected. If there is no wireless LAN adapter 59 operating in the PS mode, the process proceeds to block 217-9. Even if the wireless LAN adapter 59 operating in the extended PS mode is connected, the process proceeds to block 217-9.

  If the PS mode wireless LAN adapter 59 is connected in block 217-3, the buffer controller 161 stores the broadcast frame in the buffer 165 in block 217-7, and the data controller 163 stores the frame in the buffer 165. Notify that you have memorized. The data control unit 163 recognizes that the frame stored in the buffer 165 needs to be transmitted at the timing of the DTIM frame. In block 217-9, the buffer control unit 161 refers to the extended PS mode field of the operation mode table 157, and in the currently connected wireless LAN adapter 59, the wireless operating in the extended PS mode. It is checked whether or not the LAN adapter 59 is connected.

  If the wireless LAN adapter 59 operating in the extended PS mode is not connected, the process proceeds to block 217-5, and the buffer control unit 161 immediately transmits the broadcast frame from the wireless LAN communication unit 155. The data is sent to the control unit 163. When the wireless LAN adapter 59 operating in the extended PS mode is connected, the process proceeds to block 217-11.

  In block 217-11, the buffer control unit 161 checks whether the received packet is a magic packet frame from the destination IP address of the broadcast frame. If it is a magic packet frame, in block 217-13, the buffer control unit 161 stores the frame in the expansion buffer 167, and notifies the data control unit 163 that the data has been stored in the expansion buffer 167. Receiving the notification, the data control unit 163 needs to transmit the magic packet frame stored in the expansion buffer 167 at the timing when the wireless LAN adapter 59 operating in the extended PS mode transitions to the wake state. recognize.

  If the data control unit 163 determines in block 217-11 that the frame is not a magic packet frame, the frame is discarded in block 217-15. Accordingly, the wireless LAN adapters 59 (21a) to 59 (21c) operating in the extended PS mode do not receive broadcast frames other than magic packet frames. When the buffer control unit 161 determines in block 217-1 that the Ethernet frame received from the backbone network 11 is not a broadcast frame, it checks whether it is a multicast frame in block 217-17.

  In the case of a multicast frame, the process proceeds to block 217-3. Since the multicast frame is not a magic packet frame, the multicast frame is stored in the expansion buffer 167 even if the wireless LAN adapters 59 (23a) to 59 (23c) operating in the extended PS mode are connected. There is no. If it is determined in block 217-17 that the frame is not a multicast frame, that is, if it is determined that the frame is a unicast frame, the buffer controller 161 in block 217-19, the extended PS mode field of the operation mode table 157 And the MAC address field, it is checked whether or not the destination is the wireless LAN adapter 59 operating in the extended PS mode. If the destination is not the wireless LAN adapter 59 that operates in the extended PS mode, that is, if the destination is the wireless LAN adapter 59 that operates in the active mode or the wireless LAN adapter 59 that operates in the PS mode, the process proceeds to block 217-3. For STAs operating in PS mode, the frame is discarded at block 217-15.

  According to the procedure so far, when only the wireless LAN adapter 59 (31b) operating in the PS mode is connected, the buffer control unit 161 receives the broadcast frame and multicast frame received from the backbone network 11. Store in buffer 165. When only the wireless LAN adapters 59 (21 a) to 59 (21 c) that operate in the extended PS mode are connected, the buffer control unit 161 uses the magic packet packet in the Ethernet frame received from the backbone network 11. Only the frame is stored in the buffer 167.

  When the wireless LAN adapter 59 (31b) operating in the PS mode and the wireless LAN adapters 59 (21a) to 59 (21c) operating in the extended PS mode are connected, the broadcast frame received from the backbone network 11 Multicast frames are stored in buffer 165 and only magic packet frames are stored in buffer 167. The buffer controller 161 stores only the magic packet frame in the buffer 167 and discards the others for the wireless LAN adapters 59 (21a) to 59 (21c) that have shifted to the extended PS mode.

  The reason is that the wireless LAN adapters 59 (21a) to 59 (21c) operating in the extended PS mode are assumed to have shifted to the S3 state or the S4 state in the WOL standby state. This is because the AP 20 does not need to transmit because it cannot receive the 802.11 MAC frame. Further, by discarding Ethernet frames other than the magic packet frame, overflow of the buffer 167 can be avoided even if the wake interval becomes longer.

  Returning to FIG. 6, in block 219, one of the wireless LAN adapters 59 sends an AP 20 disassociation frame for disassociating and disconnects. The data control unit 163 deletes the registration data of the disconnected wireless LAN adapter 59 from the operation mode table 157. Therefore, the wireless LAN adapter 59 operating in the extended PS mode maintains the connection to the AP 20 until a cancellation request is received from the STA, and does not need to be associated every time the mode is shifted to the extended PS mode.

[Frame transmission procedure]
The Ethernet frame is stored in the buffer 165 and the expansion buffer 167 by the procedure of FIGS. Next, the procedure in which the AP 20 transmits the frame stored in the expansion buffer 167 and receives the received frame will start the WOL will be described with reference to the flowchart of FIG. In block 401, the frame stored in the buffer 165 is transmitted from the AP 20 to the wireless LAN adapter 59 in accordance with the 802.11 standard.

  The data control unit 163 transmits the broadcast frame and multicast frame stored in the buffer 165 immediately after transmitting the DTIM frames 2, 5, (n-3) and n shown in FIG. The transmitted broadcast frame and multicast frame can be received only by the wireless LAN adapter 59 in the wake state at the time of transmission.

  If the broadcast frame is a magic packet frame, the wireless LAN adapter 59 that has received the broadcast frame can start the WOL if it determines that the broadcast frame is a magic packet destined for itself. The unicast frame stored in the buffer 165 refers to the PVB field 323 in the TIM of the beacon frame received by the wireless LAN adapter 59 (31b) operating in the PS mode at the listen interval, and sets itself as the destination. It is recognized whether or not the frame to be stored is stored in the buffer 165. When the wireless LAN adapter 59 (31b) recognizes that a frame destined for itself is stored in the buffer 165, the wireless LAN adapter 59 (31b) transmits a control frame called Ps-Poll (Power-Save Poll) to the AP 20, Receive a cast frame.

  In subsequent procedures, the wireless LAN adapters 59 (21a) to 59 (21c) receive the magic packet frame stored in the expansion buffer 167. The extension buffer 167 stores only magic packet frames. The transmission of the magic packet frame is performed independently of the transmission of the broadcast frame from the buffer 165.

  The data control unit 163 can recognize that the wireless LAN adapter has transitioned to the wake-up state with a beacon frame in which the count value of the operation mode table 157 is zero. In block 403, the data control unit 163 refers to the extended PS mode field and the count value field of the operation mode table 157, and the extended PS mode wireless LAN in which the count value becomes 0 at the timing of the next beacon frame. Whether or not the adapter 59 exists is determined every time a beacon frame is transmitted.

  Here, the data control unit 163 determines that the wireless LAN adapter 59 (21a) and the wireless LAN adapter 59 (21c) have a count value of 0 in the beacon frame (n-2). In block 405, the data control unit 163 reads the magic packet frame from the expansion buffer 167, and transmits it from the wireless LAN communication unit 155 immediately after transmitting the beacon frame (n-2). At this time, the AP 20 transmits the magic packet frame as a broadcast frame.

  In the beacon frame (n-2), the wireless LAN adapter 59 (21a) and the wireless LAN adapter 59 (21c) that are in the wake state receive the magic packet frame. The wireless LAN adapters 59 (21a) and 59 (21c) are sufficient to receive a broadcast frame when the bit map control field 321 is set to 1 in the beacon frame (n-2). Maintain a time awake state. Each of the wireless LAN adapter 59 (21a) and the wireless LAN adapter 59 (21c) checks the destination of the magic packet frame, and the STA 21a or STA 21c that has received the magic packet addressed to itself receives the WOL in block 407. Start up. The wireless LAN adapters 59 (21a) and 59 (21c) discard magic packet frames with different destinations.

  In block 409, the data control unit 163 refers to the operation mode table 157 and stores the magic packet frame received from the backbone network 11 in the expansion buffer 167 before storing the extended PS mode in the operation mode table 157. It is determined whether or not a magic packet frame has been transmitted to all the registered wireless LAN adapters 59 (21a) to 59 (21c) when they are in the wake state. The data control unit 163 determines that the count value of the wireless LAN adapter 59 (21b) is not 0 at the timing of the beacon frame (n-2), returns to the block 403, and determines the timing of the beacon frame (n-1). Thus, it is determined that the count value of the wireless LAN adapter 59 (21b) becomes zero.

  In step 405, the data control unit 163 reads the magic packet frame from the expansion buffer 167 again and transmits it from the wireless LAN communication unit 155. The wireless LAN adapter 59 (21 b) that has received the magic packet frame starts WOL in block 407 when determining that it has received the magic packet frame destined for itself. If the data control unit 163 determines in block 409 that the magic packet frame has been transmitted to all wireless LAN adapters 59 that have registered the extended PS mode prior to receiving the magic packet frame in the wake state. The expansion buffer 167 is cleared immediately after transmitting the beacon interval (n−1) in block 411.

  Although an example in which the AP 20 transmits the magic packet frame as a broadcast frame is described in block 405, the AP 20 may transmit the magic packet frame stored in the expansion buffer 167 as a unicast frame. In this case, the AP 20 notifies each wireless LAN adapter 59 that the magic packet frame is stored in the expansion buffer 117 using the vendor specific field of the beacon frame. Then, the wireless LAN adapter 59 operating in the extended PS mode that has transitioned to the wake state can transmit and receive a control frame called PS-Poll to the AP 20.

  When the extended PS mode is set to disabled in the extended PS processing unit 107, the wireless LAN adapter 59 can operate in the PS mode and receive a magic packet frame in the WOL standby state. Even if the extended PS mode is enabled, the wireless LAN adapter 59 operates in the active mode or the PS mode without shifting to the extended PS mode except in the WOL standby state.

  Therefore, the wireless LAN adapter 59 that can operate in the extended PS mode does not affect the operation of other wireless LAN adapters that operate based on the IEEE 802.11 standard, and the interval until the wireless LAN adapter 59 transitions to the wake state in the WOL standby state. The power consumption can be reduced by lengthening. In addition, the device itself can perform an operation defined in the IEEE 802.11 standard except when operating in the WOL standby state. The present invention is particularly effective for STAs that are shifting to a WOL standby state with a battery.

 Although the present invention has been described with the specific embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and is known so far as long as the effects of the present invention are achieved. It goes without saying that any configuration can be adopted.

10 ... Wireless LAN system 153 ... Control unit

Claims (20)

A method in which a radio base station transmits a magic packet frame for WOL activation,
Receiving a notification from the wireless LAN adapter to enter an extended power save mode in which a transition is made from a doze state to an wake state at a wakeup interval longer than a DTIM interval defined in the IEEE 802.11 standard;
Measuring a timing at which the wireless LAN adapter operating in the extended power save mode transitions to the wake state based on the notification;
When the wireless base station receives the magic packet frame from the backbone network and determines that a wireless LAN adapter that operates in the extended power save mode is connected to the wireless base station, the magic Storing the packet frame in a first buffer;
Transmitting the magic packet frame stored in the first buffer at a timing when the wireless LAN adapter transitions to the wake state.   The method according to claim 1, wherein in the step of receiving the notification, the wireless base station receives the notification when a wireless terminal device equipped with the wireless LAN adapter shifts to a WOL standby state. Receiving a broadcast frame from the backbone network;
Determining whether any of a plurality of wireless LAN adapters connected to the wireless base station is operating in a power save mode defined in the IEEE 802.11 standard;
The method further comprises: storing the broadcast frame in a second buffer without storing the broadcast frame in the first buffer when it is determined that the power save mode is operating. The method described.   4. The method of claim 3, comprising transmitting the broadcast frame stored in the second buffer at the DTIM interval. Receiving a unicast frame from the backbone network;
Determining whether the destination of the unicast frame is a wireless LAN adapter operating in the extended power save mode;
5. The method according to claim 1, further comprising a step of discarding the unicast frame when it is determined that a destination is a wireless LAN adapter operating in the extended power save mode. Method.   The method according to any one of claims 1 to 5, wherein the wireless base station maintains the connection of the wireless LAN adapter while the wireless LAN adapter is operating in the extended power save mode.   The step of transmitting the magic packet frame transmits the magic packet frame at each timing when any of the plurality of wireless LAN adapters operating in the extended power save mode is transitioning to the wake state. The method according to any one of claims 1 to 6, comprising the step of:   After transmitting the magic packet frame to all wireless LAN adapters operating in the extended power save mode, the first buffer is cleared to stop transmission of the magic packet frame. The method of claim 7, comprising steps. A radio base station capable of receiving a magic packet frame for WOL activation from a backbone network,
A first buffer for storing the magic packet frame;
A second buffer capable of storing broadcast frames received from the backbone network;
When the wireless LAN adapter receives a notification of transition to the extended power save mode in which a transition is made from the doze state to the wake state at a wake-up interval longer than the DTIM interval specified in the IEEE 802.11 standard, the wireless LAN adapter transitions to the wake state. It is determined that a wireless LAN adapter that receives the magic packet frame from the backbone network and operates in the extended power save mode is connected to the timing count unit that counts timing and the backbone network A buffer controller that stores the magic packet frame in the first buffer when
A wireless base station comprising: a data control unit that transmits the magic packet frame stored in the first buffer at a timing when the wireless LAN adapter transitions to the wake state.   The buffer control unit receives a broadcast frame from the backbone network, and any one of a plurality of wireless LAN adapters connected to the wireless base station defines a power save mode defined in the IEEE 802.11 standard. The radio base station according to claim 9, wherein when it is determined that the broadcast frame is operating, the broadcast frame is stored in the second buffer without being stored in the first buffer.   The buffer control unit determines that the frame received from the backbone network is a unicast frame destined for a wireless LAN adapter operating in the extended power save mode. The radio base station according to claim 9 or 10, wherein the frame is discarded.   The data control unit transmits the magic packet frame at every timing when any one of the plurality of wireless LAN adapters operating in the extended power save mode transitions to the wake state. The radio base station according to claim 11. An operation mode table for registering the identifier of the wireless LAN adapter operating in the extended power save mode and the wake-up interval;
The data control unit deletes the registration of the wireless LAN adapter from the operation mode table when there is a disconnection request from the wireless LAN adapter operating in the extended power save mode, and the magic packet The radio base station according to any one of claims 9 to 12, which stops frame transmission.   The wireless base station according to claim 9, wherein the data control unit maintains the connection of the wireless LAN adapter until a disconnection request is issued from the wireless LAN adapter. A wireless LAN adapter mounted on a wireless terminal device receives a magic packet frame from a wireless base station, and the wireless terminal device starts WOL.
Receiving from the wireless terminal device system a notification of transition to a WOL standby state;
In response to the notification, transitioning to an extended power save mode that transitions from a doze state to an wake state at a wakeup interval longer than a DTIM interval defined in the IEEE 802.11 standard;
Notifying the radio base station of the wake-up interval;
And a step of notifying the system of the wireless terminal device to activate the WOL in response to a magic packet frame received from the wireless base station at the timing of transition to the wake state. Operating in a power save mode as defined in the IEEE 802.11 standard;
Transitioning to an wake state in the power save mode;
The method according to claim 15, further comprising: receiving a broadcast frame from the radio base station when transitioning to the wake state. A wireless LAN adapter mounted on a wireless terminal device and capable of operating in a power saving mode of a listen interval defined in the IEEE 802.11 standard,
Extended power save mode in which the wireless LAN adapter transitions from the doze state to the wake state at a wake-up interval longer than the listen interval when a notification of transition to the WOL standby state is received from the wireless terminal device system Power control means to operate with,
Notification means for notifying the radio base station of the wakeup interval when operating in the extended power save mode;
A wireless LAN adapter comprising: a WOL activation notification means for notifying the system of the wireless terminal device to activate the WOL in response to the magic packet frame received at the timing of transition to the wake state.   A wireless terminal device equipped with the wireless LAN adapter according to claim 17. In order for the radio base station to transmit a magic packet frame for WOL activation, to the radio base station,
Transmitting the broadcast frame stored in the buffer to the wireless LAN adapter at an interval that is an integral multiple of the beacon frame;
Receiving a notification that the wireless LAN adapter shifts to an extended power save mode in which a transition is made from a doze state to an wake state at a wakeup interval longer than an integer multiple of the beacon frame; and
Measuring a timing at which the wireless LAN adapter operating in the extended power save mode transitions to the wake state based on the notification;
When the wireless base station receives the magic packet frame from the backbone network and determines that a wireless LAN adapter that operates in the extended power save mode is connected to the wireless base station, the magic Storing packet frames in a buffer;
Transmitting the magic packet frame stored in the buffer at a timing when the wireless LAN adapter transitions to the wake state. In order for the wireless terminal device to start WOL on the wireless LAN adapter mounted on the wireless terminal device,
Receiving broadcast frames stored in a buffer by the radio base station while operating in a power save mode at an interval that is an integral multiple of a beacon frame; and
Receiving a notification of transition to a WOL standby state from the wireless terminal device system;
In response to the notification, transitioning to an extended power save mode that transitions from a doze state to an wake state at a wakeup interval that is longer than an integer multiple of the beacon frame; and
Notifying the radio base station of the wake-up interval;
A computer program that executes a process including a step of notifying the system of the wireless terminal device to start the WOL in response to the magic packet frame received at the timing of transition to the wake state.

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