JP2006295370A - Wireless communication terminal and management method of transmission/reception function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress power consumption of a wireless communication terminal constituting a part of a wireless LAN. <P>SOLUTION: Only a reception function is triggered for each Listen interval which is shorter than the Listen interval specified by negotiation with an access point (S2 and 3). The beacon which is received after the reception function is triggered is analyzed (S4 and 5). Once the beacon is found to contain the information about the data addressed to own terminal, a transmission function is triggered (S7). It is confirmed that no other communication is making communication (S8-12), and then PS Poll which means request for data transmission is transmitted to an access point (S13). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wireless communication terminal that communicates with other terminals via a relay device called an access point in a wireless LAN or the like, and a method for managing a transmission / reception function thereof.

  As is well known, in a wireless LAN, a wireless relay device called an access point (hereinafter abbreviated as AP) and a wireless communication terminal are connected by wireless communication. The AP is normally supplied with power at all times via a power cable, but the wireless communication terminal normally operates only with a battery in order to ensure mobility. In order to check whether or not there is data to be transmitted from the AP to its own terminal even when communication such as data and voice (hereinafter abbreviated as data) is not performed, the wireless communication terminal It is necessary to continue standby communication between the two. However, if standby communication is simply continued, power consumption increases, and the battery is quickly depleted.

  Accordingly, IEEE802.11, which is defined by the international standard for wireless LAN, defines standby communication in the power saving mode as described below, thereby reducing the power consumption of the wireless communication terminal. IEEE802.11 is described in Non-Patent Document 1 below.

  1) The AP periodically sends a signal called a beacon. This is called a beacon period. The beacon includes presence / absence information on data to be transmitted from the AP to the wireless terminal in the power saving mode (or sleep mode).

  2) Before entering the power saving mode, the wireless terminal determines to receive a beacon with N times of beacon period with the AP. The N beacon periods received by the wireless terminal in the power saving mode are generally referred to as a Listen period.

  3) A wireless terminal in the power saving mode normally stops the wireless transmission / reception function to save power consumption, temporarily activates the wireless transmission / reception function at the above Listen interval, receives the beacon, and analyzes this beacon. Then, the presence / absence information on the data addressed to the own terminal is checked.

  4) When the wireless terminal determines that there is no data addressed to itself, it again stops the wireless transmission / reception function and returns to the power saving mode.

  5) When the wireless communication terminal determines that there is data addressed to itself, it handles (a, b) in the following two ways.

a. When there is no data to be sent from the AP to the wireless terminal in the power saving mode other than the own terminal, immediately send a signal (hereinafter referred to as PS Poll) requesting the sending of data addressed to the own terminal to the AP wirelessly. .

b. When there is data to be transmitted from the AP to wireless terminals in the power saving mode other than the own terminal, two or more wireless communication terminals in the power saving mode notified that there is data to be transmitted are Send PS Poll wirelessly. At this time, if these wireless communication terminals simultaneously send out PS Poll, radio interference occurs and a transmission error occurs. Therefore, the following measures are determined by the international standard. Each wireless terminal generates a random number in accordance with a predetermined rule, and after a period corresponding to the random number (hereinafter referred to as a random number waiting time) has elapsed, when no wireless signal is received from another wireless terminal or AP , PSPol1 is transmitted to the AP wirelessly. As a result, even when two or more wireless terminals transmit PS Polls, the probability of transmitting PS Polls at different times and avoiding interference increases.

  6) The AP stores the data addressed to the wireless terminal in the power saving mode for a period corresponding to the Listen interval determined with the wireless terminal. However, if the AP cannot receive the data transmission request even if the Listen interval is exceeded and the data cannot be read, the AP discards the data addressed to the wireless terminal stored in accordance with a function called Aging.

  Here, the contents described above will be described with reference to FIGS. In these figures, in the column of “beacon transmission from AP”, vertical bars are all beacons, and among these beacons, a thick bar line is a beacon including information that there is data for a wireless terminal. The rectangular rise is data sent from the AP to the wireless terminal. In these figures, the Listen interval is an interval corresponding to three beacon cycles.

  First, referring to FIG. 8, when the AP has transmission data only for the wireless terminal 1 of the wireless terminals 1 and 2, that is, the third to fifth beacons in FIG. The case where information indicating that there is data is included will be described.

  1) The wireless terminals 1 and 2 in the power saving mode start up a wireless reception function and a transmission function at the Listen time, respectively, and prepare for reception of a beacon signal.

  2) Since the beacon at the first Listen time (second beacon in the figure) includes information indicating that there is no transmission data addressed to the wireless terminals 1 and 2, the wireless terminals 1 and 2 When it is recognized that there is no power, the wireless reception function and the transmission function are immediately turned off, and the mode again returns to the power saving mode.

  3) Since the beacon at the second Listen time (fifth beacon in the figure) includes information indicating that there is data addressed to the wireless terminal 1, the wireless terminal 1 transmits the transmission data addressed to its own terminal. After receiving this beacon, a data transmission request signal called a PS Poll signal is sent from the wireless terminal 1 to the AP after a certain time (hereinafter referred to as SIFS (Short Inter Frame Space) time). To do.

  4) Upon receiving the PS Poll signal, the AP sends data to the wireless terminal 1 after SIFS time.

  5) The wireless terminal 2 recognizes that there is no transmission data addressed to its own terminal because the beacon at the second Listen time includes information indicating that there is no data addressed to itself. Then, as in the case of the beacon at the first Listen time, the wireless reception function and the transmission function are immediately deactivated, and the mode again returns to the power saving mode.

  Next, referring to FIG. 9, when the AP has transmission data for each of the wireless terminals 1 and 2, that is, the data addressed to the wireless terminals 1 and 2 in the third to fifth beacons in the figure. When information indicating that there is is included, will be described.

  1) Similar to 1) to 3) described with reference to FIG. 8, the wireless terminals 1 and 2 in the power saving mode start up the wireless reception function and the transmission function at the Listen time, respectively. In addition, since the beacon at the first Listen time includes information indicating that there is no transmission data addressed to the wireless terminals 1 and 2, the wireless terminals 1 and 2 immediately deactivate the wireless reception function and the transmission function. Return to the power saving mode again.

  2) Since the beacon at the second Listen time (the fifth beacon in the figure) includes data addressed to the wireless terminals 1 and 2, both of the wireless terminals 1 and 2 that have received the data receive the SIFS. If PS Poll is sent immediately afterwards, radio interference will occur. Therefore, in IEEE 802.11, it is confirmed that the partner wireless terminals do not send radio signals to each other for a sum of a constant time longer than SIFS called DIFS (Distributed Inter Frame Space) and a random waiting time called backoff time. After that, sending PS Poll is specified. Therefore, here, the wireless terminal 2 sends the PS Poll first, in which the random number waiting time of the wireless terminal 2 is set shorter than the random number waiting time of the wireless terminal 1.

  2) Upon receiving the PS Poll from the wireless terminal 2, the AP transmits data addressed to the wireless terminal 2 after SIFS time.

  3) After receiving the data, the wireless terminal 2 lowers the wireless transmission / reception function or expects the transmission / reception to continue and keeps the wireless transmission / reception function started.

  4) Once the data transmission from the AP to the wireless terminal 2 is completed, the wireless terminal 1 again, again to avoid interference with the wireless transmission between the other wireless terminals and the AP, the DIFS + random waiting time Wait until it elapses, and after confirming that there is no wireless transmission between the other wireless terminal and the AP, send PS Poll to the AP.

  4) When the AP receives the PS Poll from the wireless terminal 1, it sends the data to the wireless terminal 1 after SIFS.

  As described above, in the prior art, when the Listen time is reached, the wireless reception function is activated to receive the beacon from the AP, and immediately when the received beacon includes information indicating that there is data. In order to send PS Poll to AP, a wireless transmission function is also launched. In this way, when the Listen time comes, not only the wireless reception function but also the wireless transmission function is activated. As described above, even if the Listen time + the standby time elapses, the AP sends a PS Poll from the wireless terminal. This is because when data cannot be received, transmission data to the wireless terminal is discarded by the Aging function, and further, a certain time is required for starting up the wireless transmission function.

IEEE802.11Handbook, IEEEPress, NewYork, 1999. [SAE98] P.Schramm

  As described above, since most of the wireless communication terminals are battery-powered, the prior art attempts to save power by starting up the reception function and transmission function at the Listen time. Hopes to use the wireless communication terminal for a long time with further power saving.

  Accordingly, an object of the present invention is to provide a wireless communication terminal capable of further reducing power consumption and a method for managing this transmission / reception function in order to meet such a demand.

An invention relating to a wireless communication terminal for solving the above problems
A relay comprising a wireless transmission means and a wireless reception means, each of the wireless transmission means and the wireless reception means having a power saving mode and an operation mode, and emitting a beacon including information on presence / absence of transmission data addressed to a terminal at a constant cycle In a wireless communication terminal that communicates with other terminals via a device,
Listen interval setting means for determining a Listen interval for a plurality of cycles of the beacon with the relay device;
A shortened Listen interval setting means for defining a shortened Listen interval shorter than the Listen interval by at least one cycle of the beacon;
Analyzing the beacon received by the wireless reception unit in the operation mode, and determining whether there is transmission data to be transmitted from the relay device;
When the wireless reception means is in the power saving mode, the wireless reception means is activated and shifted to the operation mode at each shortened Listen interval, and the beacon received during the operation mode is received by the beacon analysis means. As a result of analysis, when it is determined that there is no transmission data to be transmitted from the relay device, a reception function management unit that shifts the wireless reception unit in the operation mode to the power saving mode;
When the beacon received by the wireless reception unit in the operation mode is analyzed by the beacon analysis unit, when it is determined that there is transmission data addressed to the terminal from the relay device, the wireless in the power saving mode A transmission function management means for starting up the transmission means and shifting to the operation mode;
A transmission request management unit that causes the relay device to transmit a transmission request for the transmission data addressed to the terminal, to the wireless transmission unit in the operation mode;
It is characterized by having.

  Note that the power saving mode of the wireless transmission means and the wireless reception means is a mode in which the power supply to at least a part of the components of each means is cut off so that the means cannot operate. The operation mode of the wireless receiving means is a mode in which power is supplied to each means and the means can operate.

Here, in the wireless communication terminal,
The transmission request management means, as a result of analyzing the beacon received by the wireless reception means in the operation mode by the beacon analysis means, in addition to the transmission data addressed to the own terminal from the relay device, When it is determined that there is transmission data, a random number is generated, and after waiting for a time corresponding to the random number, the wireless transmission means in the operation mode transmits a transmission request for transmission data addressed to the terminal. Also good.

In each of the above wireless communication terminals,
Monitoring means for monitoring radio waves received by the wireless reception means in the operation mode to determine whether the relay apparatus and another wireless communication terminal capable of communicating with the relay apparatus are communicating. Prepared,
The transmission request management means, when the monitoring means determines that the relay device and the other wireless communication terminal are not communicating, transmits the transmission addressed to the own terminal to the wireless transmission means in the operation mode. A data transmission request may be transmitted.

In addition, a method for managing a transmission / reception function of a wireless communication terminal for achieving the above object is as follows:
A relay comprising a wireless transmission means and a wireless reception means, each of the wireless transmission means and the wireless reception means having a power saving mode and an operation mode, and emitting a beacon including information on presence / absence of transmission data addressed to a terminal at a constant cycle In a method for managing a transmission / reception function of a wireless communication terminal that communicates with another terminal via a device,
Listen interval setting step for determining a Listen interval for a plurality of cycles of the beacon with the relay device;
A shortened Listen interval setting step for defining a shortened Listen interval that is shorter than the Listen interval by at least one period of the beacon;
Analyzing the beacon received by the wireless reception means in the operation mode, and determining whether there is transmission data to be transmitted from the relay device; and
When the wireless reception means is in the power saving mode, the wireless reception means is activated and shifted to the operation mode at each shortened Listen interval, and the beacon received during the operation mode is received by the beacon analysis means. As a result of analysis, when it is determined that there is no transmission data to be transmitted from the relay device, a reception function management step for shifting the wireless reception unit in the operation mode to the power saving mode;
As a result of analyzing the beacon received by the wireless reception means in the operation mode in the beacon analysis step, if it is determined that there is transmission data addressed to the terminal from the relay device, the wireless in the power saving mode A transmission function management step of starting up the transmission means and shifting to the operation mode;
A transmission request management step for causing the relay apparatus to transmit a transmission request for the transmission data addressed to the terminal, to the wireless transmission means in the operation mode;
It is characterized by including.

  According to the present invention, when a beacon from a relay device such as an access point is received and analyzed, only the reception function is activated and the beacon is analyzed, and there is transmission data addressed to the terminal itself. In addition, since the transmission function is activated for the first time, the power consumption of the wireless communication terminal can be suppressed.

  Hereinafter, an embodiment of a wireless communication terminal according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the wireless communication terminals of this embodiment are wireless LAN cards 20, 20a, 20c and a wireless LAN board 20b. Each of the wireless LAN cards 20, 20a, 20c is used by being attached to the computers 10, 10a, 10c, and the wireless LAN board 20b is used in a state of being attached to the computer 10b in advance.

  Each wireless LAN card or the like communicates wirelessly with access points (AP) 50, 50a, and 50b that are relay devices. Each AP 50, 50a, 50b is connected to the routers 2, 2a by wire, and these routers 2, 2a are connected to a public network 1 such as the Internet. Computers 3 and 3a may be wired to the routers 2 and 2a.

  For example, the wireless LAN card 20 can transmit data to any terminal connected to the wireless LAN system described above by designating a destination terminal and transmitting the data received from the computer 10 to the AP 50. .

  As shown in FIG. 2, the computers 10, 10 a, and 10 c to which the wireless LAN cards 20, 20 a, and 20 c are attached include a memory such as a ROM 12 and a RAM 13, a CPU 11 that executes a program stored in the memory, and a man A machine interface 14, these operating power supplies 15, and a card slot 16 for mounting the wireless LAN cards 20, 20a, 20c are provided. An input device 17 such as a keyboard and an output device 18 such as a display are connected to the man-machine interface 14.

  Each of the wireless LAN cards 20, 20a, and 20c includes a communication processing unit 21, a wireless transmission unit 30 that transmits data according to an instruction from the wireless communication processing unit 21, and a wireless reception unit that receives transmission data from the AP. 35, an antenna 41 for transmitting a signal modulated by the wireless transmission unit 30 and receiving a radio wave from the outside, and a power control unit 40 for controlling power from the power source 15 of the computers 10, 10a, 10c, It is equipped with.

  The communication processing unit 21 functionally determines a Listen interval setting unit 22 that determines a Listen interval for a plurality of beacons by discussion with an AP, and a shortened Listen interval that is at least one beacon period shorter than the Listen interval. The shortened Listen interval setting unit 23, the beacon analysis unit 24 that analyzes the content of the beacon transmitted by the AP, and the power supply control unit 40 are set so that the wireless reception unit 35 is set to either the power saving mode or the operation mode. The reception function management unit 26, the transmission function management unit 27 that works on the power supply control unit 40 to set the wireless transmission unit 30 to either the power saving mode or the operation mode, and the radio wave received by the wireless reception unit 35. The monitoring unit 28 to be monitored, the transmission request management unit 29 that causes the wireless transmission unit 30 to transmit the PS Poll that is a data transmission request, and the operations of these units 22 to 24 and 26 to 29 are controlled. It has a control unit 25, a. Each of these functions functions when a CPU mounted on a wireless LAN card executes a program stored in a memory mounted on the wireless LAN card.

  The wireless transmission unit 30 includes a transmission buffer 31 that temporarily stores data to be transmitted, a D / A converter 32 that converts digital transmission data from the transmission buffer 31 into an analog signal, and the analog signal. A modulation unit 33 that performs modulation processing and an amplifier 34 that amplifies the modulated signal are provided. The wireless reception unit 35 also includes an amplifier 39 that amplifies the signal received by the antenna, a demodulation unit 38 that performs demodulation processing on the signal from the amplifier, and an A / D that converts the demodulated analog signal into a digital signal. A converter 37 and a reception buffer 36 for temporarily storing a digital signal from the A / D converter 37 are provided.

  The transmission function management unit 27 described above operates in the power saving mode in which the power to the D / A converter 32, the modulation unit 33, and the amplifier 34 of the wireless transmission unit 30 described above is cut off by acting on the power supply control unit 40. And an operation mode for supplying power to them. In addition, the reception function management unit 26 also works on the power supply control unit 40 to set the power saving mode in which the power to the A / D converter 37, the demodulation unit 38, and the amplifier 39 of the wireless reception unit 35 described above is cut off. And an operation mode for supplying power to them.

  The wireless LAN board 20b is different from the wireless LAN card 20 in that it cannot be easily removed, but its function is basically the same as the function of the wireless LAN card 20 described above.

  As shown in FIG. 3, each of the APs 50, 50a, and 50b includes a communication processing unit 51, a wireless transmission unit 55 that transmits data according to an instruction from the communication processing unit 51, a wireless reception unit 56, and a wired transmission / reception unit. 57, a memory 58 for storing various programs and data, and an antenna 59 for wireless communication with the wireless LAN cards 20, 20a, 20c and the wireless LAN board 20b.

  The communication processing unit 51 functionally includes a listen interval setting unit 52 that determines a listen interval for a plurality of beacon periods in consultation with each wireless terminal, a beacon information generation unit 53 that creates information to be included in the beacon, And a buffer management unit 54 that manages the buffers in the wireless transmission / reception units 55 and 56 and the buffer in the wired transmission / reception unit 57. Each of these functions functions when a CPU mounted on the AP executes a program stored in a memory that is also mounted on the AP.

  The beacon signal emitted by the AP 50 is defined by IEEE802.11, and the beacon signal includes information such as a duration, a reception address, a transmission address, a beacon interval, and a parameter defined by an information element. . The beacon information generation unit 53 generates such information. Information in the beacon signal, “parameter defined by the information element” includes information called a traffic notification map (TIM), and data to be transmitted to any wireless communication terminal is included in this traffic notification map. Data indicating whether or not there is written.

  Next, of the wireless LAN cards 20, 20a, 20c and the wireless LAN board 20b described above, the operation of the wireless LAN card 20 will be described as a representative.

  The wireless LAN card 20 performs wireless communication with the AP 50 for communication with other terminals, and when the wireless communication ends, the Listen interval setting unit 22 of the wireless LAN card 20 is activated, The wireless communication unit 30 requests the AP 50 to set a listen interval setting. When receiving this request, the listen interval setting unit 52 of the AP 50 negotiates with the listen interval setting unit 22 of the wireless LAN card 20 to determine the listen interval. For convenience of the following description, it is assumed here that three periods of beacons emitted by the AP 50 are Listen intervals.

  When the above discussion is completed, the reception function management unit 25 of the wireless LAN card 20 works on the power supply control unit 40 to cut off the power supply to the A / D converter 37, the demodulation unit 28, and the amplifier 39 of the wireless reception unit 35. The wireless reception unit 35 is set to the power saving mode. The transmission function management unit 27 of the wireless LAN card 20 also works on the power supply control unit 40 to cut off the power supply to the D / A converter, the modulation unit 33, and the amplifier 34 of the wireless transmission unit 30, and Set to power saving mode. Further, the shortened Listen interval setting unit 23 of the wireless LAN card 20 sets a shortened Listen interval that is at least one beacon period shorter than the Listen interval previously determined by the Listen interval setting unit 22, and the control unit 25 sets the shortened Listen timer. to start. For the convenience of the following explanation, it is assumed here that the interval shorter by one beacon period than the Listen interval, that is, the interval corresponding to two beacon periods is a shortened Listen interval, but the interval shorter by several beacon periods than the Listen interval is shortened. It is good also as Listen interval.

  As shown in the flowchart of FIG. 4, the control unit 25 of the wireless LAN card 20 waits for the shortened Listen timer to be 0, in other words, when the shortened Listen time is reached. This is notified to the unit 26 (S1, 2). Receiving this notification, the reception function management unit 26 operates the power supply control unit 40 to supply power to the A / D converter 37, the demodulation unit 38, and the amplifier 39 of the wireless reception unit 35 in the power saving mode. The wireless receiver 35 is set to the operation mode (S3). As shown in FIGS. 6 and 7, when the beacon is transmitted from the AP 50, the wireless reception unit 35 must be fully up and ready to receive this beacon. The above-described shortened listen timer is set so that the time slightly before the time of issuing the time becomes the shortened listen time.

  Subsequently, the control unit 25 determines whether or not the wireless reception unit 35 in the operation mode has received a beacon from the AP 50 (S4). If the beacon is received, the beacon analysis unit 24 analyzes the beacon. Is executed. The beacon analysis unit 24 determines whether there is data addressed to its own terminal as a result of the analysis of the beacon (S5). When the beacon analysis unit 24 determines that there is no data addressed to its own terminal, the control unit 25 activates the shortened listen timer, the reception function management unit 26 works on the power supply control unit 40, and the A / D of the wireless reception unit 35. The power is cut off to the converter 37, the demodulator 38, and the amplifier 39, and the radio receiver 35 is again set to the power saving mode (S6). When step 6 ends, the process returns to step 1 described above. In addition, between the above steps 1 to 6, the wireless reception unit 35 temporarily enters the operation mode, but the wireless transmission unit 30 remains in the power saving mode during this period.

  If the beacon analysis unit 24 determines in step 5 that there is data addressed to itself, the transmission function management unit 27 works on the power supply control unit 40 to perform D / A conversion of the wireless transmission unit 30 in the power saving mode. Power is supplied to the device 32, the modulation unit 33, and the amplifier 34, and as shown in FIGS. 6 and 7, the wireless transmission unit 30 is activated, that is, the wireless transmission unit 30 is set to the operation mode (S7). Subsequently, the transmission request management unit 29 generates a random number, sets a random waiting time corresponding to the random number, and waits for the random waiting time to elapse (S8). During this random number waiting time, the monitoring unit 28 monitors communication of another device, specifically, communication between the AP 50 and the other wireless communication terminal 20a, etc., and has received communication of the other device? It is determined whether or not (S9). The monitoring unit 28 monitors the amplifier 24 of the wireless transmission unit 30 and determines whether or not a communication of another device has been received depending on whether or not a signal having a certain voltage is input to the amplifier 24. To do.

  When the monitoring unit 28 determines that the communication of another device is received, the monitoring unit 28 waits until the communication is completed. When the communication is completed, the monitoring unit 28 determines whether the communication is a beacon from the AP 50. Judgment is made (S10). If it is not a beacon, that is, if it is data communication between the AP 50 and another wireless communication terminal 20a, the process returns to the above-described step 8, and the transmission request management unit 29 again waits for a random number as shown in FIG. Set the time. If the received communication is a beacon, the process proceeds to step 16 in the flowchart of FIG. If it is determined in step 9 that the monitoring unit 28 has not received communication from another device, the transmission request management unit 29 determines that the above-described random number waiting time has elapsed (S11), and After confirming that the start-up of the wireless transmission unit 30 has been completed (S12), the wireless transmission unit 30 is caused to transmit a PS Poll indicating a data transmission request (S13). Note that when it is determined that the random number waiting time has elapsed (S11), it has not yet elapsed, and when the start of the wireless transmission function has been completed (S12), it is not yet completed. If it is determined that there is not, the process returns to step 9 again.

  When the wireless LAN card 20 transmits PS Poll (S13), the AP 50 receives this and transmits data to the wireless LAN card 20 that is the transmission source of PS Poll.

  When confirming the data reception from the AP 50, the control unit 25 of the wireless LAN card 20 causes the wireless transmission unit 30 to transmit Ack (S14). Further, the control unit 25 starts the shortened Listen timer, the transmission function management unit 27 sets the wireless transmission unit 30 to the power saving mode, and the reception function management unit 26 sets the wireless reception unit 35 to the power saving mode (S15), Return to step 1.

  That is, the wireless LAN card 20 activates the wireless transmission function when it is determined in step 5 that there is data addressed to its own terminal, and when no other device is performing communication and the random time has elapsed, A PS Poll is transmitted to the AP 50, and data is acquired from the AP 50.

  If it is determined in step 10 that the received communication is a beacon, as shown in the flowchart of FIG. 5, the beacon analysis unit 24 analyzes this beacon to determine whether there is data addressed to the terminal itself. Judgment is made (S16). When the beacon analysis unit 24 determines that there is no data addressed to its own terminal, the control unit 25 activates the shortened listen timer and the reception function management unit 26 omits the wireless reception unit 35, as in the process of step 15 described above. In the power mode, the transmission function management unit 27 sets the wireless transmission unit 30 in the power saving mode (S23). Then, the process returns to step 1.

  If the beacon analysis unit 24 determines in step 16 that there is data addressed to its own terminal, it further determines whether there is data addressed to another terminal (S17). If the AP 50 has data destined for another terminal in addition to the data destined for the own terminal, the transmission request management unit 29 generates a random number, sets a random number waiting time corresponding to the random number, and sets the random number waiting time. (S18). During this random number waiting time, the monitoring unit 28 monitors the communication of the other device and determines whether the communication of the other device has been received (S19). When the monitoring unit 28 determines that the communication of another device is received, the monitoring unit 28 waits until the communication is completed. When the communication is completed, the monitoring unit 28 returns to step 18 and the transmission request management unit 29 again. Set a random waiting time and wait for the random waiting time to elapse. When the monitoring unit 28 determines that the communication of another device has not been received, the transmission request management unit 29 determines whether or not the above-described random number waiting time has elapsed (S20), and this random number If the waiting time has elapsed, the wireless transmission unit 30 is caused to transmit PS Poll (S21). If it is determined in step 17 that there is no data addressed to another terminal, the transmission request management unit 29 immediately causes the wireless transmission unit 30 to transmit PS Poll (S21). If it is determined that the random waiting time has not elapsed (S20), the process returns to step 19 again.

  When the wireless LAN card 20 transmits PS Poll (S21), the AP 50 receives this and transmits data to the wireless LAN card 20 that is the transmission source of PS Poll.

  When confirming the data reception from the AP 50, the control unit 25 of the wireless LAN card 20 causes the wireless transmission unit 30 to transmit Ack (S22). Further, the control unit 25 starts the shortened Listen timer, the transmission function management unit 27 sets the wireless transmission unit 30 to the power saving mode, and the reception function management unit 26 sets the wireless reception unit 35 to the power saving mode (S23). Return to step 1.

  Next, the operation of the wireless LAN card 20 will be described again using the timing charts of FIGS. 6 and 7. In these figures, in the column of “beacon transmission from AP 50”, each vertical bar is a beacon, and among these beacons, a thick bar line includes information indicating that there is data for the wireless LAN card 20. It is a beacon. Also, in the same column, the rectangular rise is data sent from the AP 50 to the wireless LAN card 20.

  First, an example of transmitting a PS Poll after detecting a beacon at a shortened Listen time and before detecting the next beacon will be described using the timing chart of FIG.

  When the first shortened Listen time is reached (S2), the wireless reception function is activated (S3), and when the detected beacon does not include information indicating that there is data addressed to the own terminal (S4), the shortened Listen timer is set. While starting, the wireless reception function is deactivated (S6).

  When the shortened Listen time is reached again (S2), the wireless reception function is activated (S3), and when the detected beacon includes information indicating that there is data addressed to the own terminal (S4), the transmission function is activated. (S7), a random waiting time is set (S8). When the communication of another device is received after starting the transmission function, the communication of the other device is completed so that this communication and the transmission of the PS Poll by the terminal 20 do not interfere with each other. (S9), a random waiting time is set again (S8). If communication of another device is not received during the new random number waiting time (S9), the system waits for the random number waiting time to elapse (S11) and transmits PS Poll (S13).

  Since the PS Poll is transmitted before detecting the next beacon after detecting the beacon at the shortened Listen time, as described above, the AP 50 transmits the terminal 20 before transmitting the next beacon. Therefore, the next beacon does not include information indicating that there is data addressed to the terminal.

  First, an example in which a PS Poll is transmitted after detecting a beacon at a shortened Listen time and further detecting the next beacon will be described using the timing chart of FIG.

  Similar to the case of FIG. 6, when the first shortened Listen time is reached (S2), the wireless reception function is activated (S3), and the detected beacon does not include information indicating that there is data addressed to the terminal (S4) ), The wireless reception function is deactivated while starting the shortened listen timer (S6).

  Further, when the shortened Listen time is reached again, as in the case of FIG. 6, the wireless reception function is activated (S3), and the detected beacon includes information indicating that there is data addressed to the own terminal ( In S4), the transmission function is activated (S7), and a random waiting time is set (S8). When the communication of another device is received after starting the transmission function, the communication device waits for the communication of the other device to be completed (S9). Finally, when the communication of the other device is completed, It is determined whether this communication is a beacon (S10). If this communication is a beacon, this beacon is analyzed (S16, 17). As a result of the analysis, if the beacon includes information indicating that there is data addressed to the own terminal and also includes information indicating that there is data addressed to another terminal, a random number waiting time is set again ( S18). If communication of another device is not received during the new random number waiting time (S19), the system waits for the random number waiting time to elapse (S20) and transmits PS Poll (S21).

  As described above, in this embodiment, when receiving a beacon from the AP 50 and analyzing it, only the reception function is activated and the transmission function is not activated. The power consumption of the card 20 or the like can be suppressed. However, since the reception function is started at a timing determined by a shortened Listen interval shorter than the Listen interval determined in consultation with AP50, the power consumption limited to the reception function only slightly increases compared to the prior art. .

  By the way, if the reception function is started up at the Listen interval, as in the prior art, the beacon received at the start of this reception function is analyzed, and information indicating that this beacon has data addressed to its own terminal is displayed. Even if the transmission function is activated and PS Poll is transmitted after the transmission function is found to be included, the AP 50 stores the transmission buffer 55a (FIG. 3) of the wireless transmission unit 55 by the Aging function by the buffer management unit 54 of the AP 50. There is a risk of discarding the stored data addressed to the terminal. However, in this embodiment, since the reception function is started at a timing determined by a shortened Listen interval shorter than the Listen interval determined by the discussion with the AP 50, the beacon received at the start of this reception function is analyzed, and this Even if PS Poll is transmitted after it is determined that the beacon contains information indicating that there is data addressed to the terminal itself, the AP 50 Aging function prevents the data addressed to the terminal from being discarded. Can do.

1 is a system diagram of a wireless LAN system in an embodiment according to the present invention. It is a functional block diagram of the wireless LAN card in one Embodiment which concerns on this invention. It is a functional block diagram of the access point in one Embodiment which concerns on this invention. It is a flowchart (the 1) which shows operation | movement of the wireless LAN card in one Embodiment which concerns on this invention. It is a flowchart (the 2) which shows operation | movement of the wireless LAN card in one Embodiment which concerns on this invention. It is a timing chart (the 1) which shows the operation timing of the wireless LAN card in one Embodiment which concerns on this invention. It is a timing chart (the 2) which shows the operation timing of the wireless LAN card in one Embodiment which concerns on this invention. It is a timing chart (the 1) which shows the operation timing of the radio | wireless communication terminal of a prior art. It is a timing chart (the 2) which shows the operation timing of the radio | wireless communication terminal of a prior art.

Explanation of symbols

1: public network, 2: router, 3: wired terminal, 10, 10a, 10b, 10c: computer, 20, 20a, 20c: wireless LAN card (wireless communication terminal), 20b: wireless LAN board (wireless communication terminal), 21: Communication processing unit, 22: Listen interval setting unit, 23: Shortened listen interval setting unit, 24: Beacon analysis unit, 25: Control unit, 26: Reception function management unit, 27: Transmission function management unit, 28: Monitoring unit , 29: transmission request management unit, 30: wireless transmission unit, 35: wireless reception unit, 40: power supply control unit, 41: antenna, 50, 50a, 50b: access point (relay device), 51: communication processing unit, 52 : Listen interval setting unit, 53: Beacon information generation unit, 54: Buffer management unit, 55: Wireless transmission unit, 56: Wireless reception unit, 57: Wired transmission / reception unit

Claims (5)

A relay comprising a wireless transmission means and a wireless reception means, each of the wireless transmission means and the wireless reception means having a power saving mode and an operation mode, and emitting a beacon including information on presence / absence of transmission data addressed to a terminal at a constant cycle In a wireless communication terminal that communicates with other terminals via a device,
Listen interval setting means for determining a Listen interval for a plurality of cycles of the beacon with the relay device;
A shortened Listen interval setting means for defining a shortened Listen interval shorter than the Listen interval by at least one cycle of the beacon;
Analyzing the beacon received by the wireless reception unit in the operation mode, and determining whether there is transmission data to be transmitted from the relay device;
When the wireless reception means is in the power saving mode, the wireless reception means is activated and shifted to the operation mode at each shortened Listen interval, and the beacon received during the operation mode is received by the beacon analysis means. As a result of analysis, when it is determined that there is no transmission data to be transmitted from the relay device, a reception function management unit that shifts the wireless reception unit in the operation mode to the power saving mode;
When the beacon received by the wireless reception unit in the operation mode is analyzed by the beacon analysis unit, when it is determined that there is transmission data addressed to the terminal from the relay device, the wireless in the power saving mode A transmission function management means for starting up the transmission means and shifting to the operation mode;
A transmission request management unit that causes the relay device to transmit a transmission request for the transmission data addressed to the terminal, to the wireless transmission unit in the operation mode;
A wireless communication terminal comprising: The wireless communication terminal according to claim 1,
The transmission request management means, as a result of analyzing the beacon received by the wireless reception means in the operation mode by the beacon analysis means, in addition to the transmission data addressed to the own terminal from the relay device, When it is determined that there is transmission data, generate a random number, wait for a time corresponding to the random number, and cause the wireless transmission means in the operation mode to transmit a transmission request for transmission data addressed to the terminal.
A wireless communication terminal characterized by the above. The wireless communication terminal according to any one of claims 1 and 2,
Monitoring means for monitoring radio waves received by the wireless reception means in the operation mode to determine whether the relay apparatus and another wireless communication terminal capable of communicating with the relay apparatus are communicating. Prepared,
The transmission request management means, when the monitoring means determines that the relay device and the other wireless communication terminal are not communicating, transmits the transmission addressed to the own terminal to the wireless transmission means in the operation mode. Send a request to send data,
A wireless communication terminal characterized by the above. In the radio | wireless communication terminal as described in any one of Claim 1 to 3,
A wireless communication card or a wireless communication circuit board mounted on the computer;
A wireless communication terminal characterized by the above. A relay comprising a wireless transmission means and a wireless reception means, each of the wireless transmission means and the wireless reception means having a power saving mode and an operation mode, and emitting a beacon including information on presence / absence of transmission data addressed to a terminal at a constant cycle In a method for managing a transmission / reception function of a wireless communication terminal that communicates with another terminal via a device,
Listen interval setting step for determining a Listen interval for a plurality of cycles of the beacon with the relay device;
A shortened Listen interval setting step for defining a shortened Listen interval that is shorter than the Listen interval by at least one period of the beacon;
Analyzing the beacon received by the wireless reception means in the operation mode, and determining whether there is transmission data to be transmitted from the relay device; and
When the wireless reception means is in the power saving mode, the wireless reception means is activated and shifted to the operation mode at each shortened Listen interval, and the beacon received during the operation mode is received by the beacon analysis means. As a result of analysis, when it is determined that there is no transmission data to be transmitted from the relay device, a reception function management step for shifting the wireless reception unit in the operation mode to the power saving mode;
As a result of analyzing the beacon received by the wireless reception means in the operation mode in the beacon analysis step, if it is determined that there is transmission data addressed to the terminal from the relay device, the wireless in the power saving mode A transmission function management step of starting up the transmission means and shifting to the operation mode;
A transmission request management step for causing the relay apparatus to transmit a transmission request for the transmission data addressed to the terminal, to the wireless transmission means in the operation mode;
A method for managing a transmission / reception function of a wireless communication terminal.

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