JP2010114809A - Wireless communication system, radio communication terminal and radio base station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem, wherein when a radio communication terminal that operates under a power-saving mode requests transmission of a communication frame addressed to the terminal itself, if another radio communication terminal is conducting communication frame transmission with identical timing, the transmission start of the transmission request frame is delayed and power consumption is increased, as a result. <P>SOLUTION: In a wireless communication system, a radio communication terminal STA1, STA2 receives a beacon 101, which is periodically transmitted by a radio base station and when it is confirmed from a traffic indication map (TIM) field of the beacon 101, that a communication frame 102 addressed to the radio communication terminal which operates under power-saving mode is being buffered in the radio base station, a communication sequence is controlled so as to prevent it from starting for a fixed interval. Thus, timing of a PS-Poll frame 103 as a transmission request of the radio communication terminal that operates under the power saving mode can be prevented, as far as is possible, from being delayed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication system, a wireless communication terminal, and a wireless base station, which are useful in wireless communication such as a wireless LAN (Local Area Network).

  In recent years, wireless networks such as IEEE802.11 have been widely used in businesses and homes because of the advantages of removing the troublesomeness of wiring in a wired network and flexibly changing the layout of terminals.

  In IEEE 802.11, access control to wireless media is mainly performed by a CSMA / CA (Carrier Sense Multiple Access / Collision Avidance) method. The CSMA / CA method is a connection method in which multiple access is performed based on carrier detection. A wireless communication terminal confirms that communication frames of other terminals are not transmitted, and then transmits its own communication frame. By starting, the collision of communication frames is avoided. The wireless communication terminal monitors the state of the wireless medium, and transmits a communication frame when there is no transmission signal for a predetermined fixed time or longer.

  An IEEE 802.11 wireless base station periodically broadcasts a beacon including network information. Since the beacon includes a parameter indicating the beacon transmission cycle, the wireless communication terminal can know the beacon cycle by receiving the beacon when connecting to the network.

  IEEE802.11 operates as a wireless communication terminal in a power saving mode in which a wireless communication terminal that operates in an active mode capable of receiving a communication frame at all times and a state in which a communication frame can be received intermittently and a state in which the communication frame cannot be received are repeated. Wireless communication terminals to be used are defined. The beacon includes a TIM (Traffic Indication Map) field that is information indicating that a communication frame addressed to the wireless communication terminal in the power saving mode is buffered, and the wireless communication terminal operating in the power saving mode is By receiving the beacon and analyzing the TIM field, it is possible to know whether a communication frame addressed to the terminal itself is buffered in the radio base station. The wireless communication terminal operating in the power saving mode has a Doze state and an Awake state. In the Doze state, communication frames cannot be transmitted / received, but operates with low power consumption. In the Awake state, transmission / reception of communication frames is not possible. Yes, but consumes more power than Doze state. The wireless communication terminal operating in the power saving mode periodically repeats the Doze state and the Awake state, for example, once in every few beacon cycles, enters the Awake state, receives a beacon, and communicates to its own terminal. It is confirmed whether there is a frame. If there is a communication frame addressed to the terminal itself, the reception process is continued in the Awake state, and then the state transitions to the Doze state. When there is no communication frame addressed to the terminal itself, immediately after receiving the beacon, the state transits to the Doze state, and the power consumption is suppressed by maintaining the Doze state with as little power consumption as possible.

  In Patent Document 1, when there are a wireless communication terminal that operates in the power saving mode and a wireless communication terminal that operates in the active mode, and a communication frame addressed to the wireless communication terminal in the power saving mode is buffered in the wireless base station, The power mode wireless communication terminal operates in the power saving mode by transmitting a communication frame addressed to the power saving mode wireless communication terminal in preference to the transmission to the active mode wireless communication terminal during the period of the awake state. We have proposed a system that can reduce the power consumption of wireless communication terminals.

Japanese Patent Laid-Open No. 9-162798 (page 11, FIG. 1)

  In a wireless system that accesses wireless media using the CSMA / CA method, a communication frame can be transmitted when there is no transmission signal on the wireless medium for a specified fixed time or longer. If another wireless communication terminal is transmitting a communication frame, it is necessary to wait until the transmission is completed.

  Furthermore, when considering a beacon in IEEE 802.11, a wireless communication terminal operating in the power saving mode can check, for example, the number of beacon periods in order to check whether a communication frame addressed to itself is buffered in the wireless base station. Attempts to receive a beacon at a rate of once, and transitions to the Awake state to perform a beacon receiving operation. To receive a beacon, analyze the TIM field of the beacon, and confirm that the communication frame addressed to itself is buffered in the radio base station. Then, a PS-Poll frame for a transmission request is transmitted to the radio base station to notify that it is in an Awake state. When the wireless base station receives the PS-Poll frame and confirms that the wireless communication terminal is in the Awake state, the wireless base station transmits the buffered communication frame to the wireless communication terminal that has transmitted the PS-Poll frame. The wireless communication terminal receives the communication frame and confirms the More Data field and the More Fragments field of the communication frame to confirm that the wireless base station has no further communication frame addressed to itself, or the TIM field of the subsequent beacon. The state of Awake is maintained until it is confirmed that there is no communication frame addressed to the own terminal.

  That is, when the wireless communication terminal operating in the power saving mode confirms that the communication frame addressed to itself is buffered by the TIM field of the beacon, and tries to transmit the PS-Poll frame, the other wireless communication is performed at the same timing. If the terminal is transmitting a communication frame, the transmission start of the transmission request frame is delayed, and during that time, it is necessary to maintain the awake state. Therefore, the time for maintaining the awake state is increased by the delayed time, resulting in consumption. There was a problem that electric power increased.

  In the invention of Patent Document 1, when a communication frame addressed to a wireless communication terminal in the power saving mode is buffered in the wireless base station during a period when the wireless communication terminal in the power saving mode is in the Awake state, wireless communication in the active mode is performed. Prior to transmission to the terminal, the frame addressed to the wireless communication terminal in the power saving mode is transmitted, and the same when the transmission request frame is transmitted from the wireless communication terminal in the power saving mode to the wireless base station. Communication frames are transmitted from other wireless communication terminals at the timing, and control is not performed to suppress them.

  Therefore, in view of the above, the present invention confirms that the communication frame addressed to the wireless communication terminal in the power saving mode is buffered in the wireless base station by the TIM field of the beacon. The beacon TIM field indicates that the wireless communication terminal with the lower priority is controlled not to start the communication sequence for a certain period of time, or that only the communication frame addressed to the wireless communication terminal with the highest priority is buffered in the wireless base station. Are provided, and a radio base station, a radio communication terminal, and a radio communication system that perform control so as not to delay the timing of the PS-Poll frame of a radio communication terminal operating in a power saving mode as much as possible For the purpose.

  A wireless communication system according to a first aspect of the present invention includes a wireless base station that transmits a beacon at regular intervals, a first wireless communication terminal that operates in a mode in which wireless communication with the wireless base station is always possible, And a second wireless communication terminal that operates in a mode capable of intermittent wireless communication with the wireless base station. The beacon includes a TIM (Traffic Indication Map) field indicating that a communication frame addressed to the second wireless communication terminal is buffered. A first step in which the wireless base station transmits the beacon to the first wireless communication terminal and the second wireless communication terminal; and the second wireless communication terminal analyzes the TIM field and And a second step of making a transmission request to the radio base station when a communication frame addressed to the terminal is buffered in the radio base station, wherein in the second step, the first radio communication terminal When the communication frame addressed to the second wireless communication terminal is buffered in the wireless base station by analyzing the TIM field, the communication sequence with the wireless base station is not started for a certain period of time.

  A wireless communication system according to a second aspect of the present invention includes a wireless base station that transmits a beacon at regular intervals, and a plurality of wireless communication terminals that operate in a mode that allows intermittent wireless communication with the wireless base station. Are provided. The beacon includes a TIM field indicating that communication frames addressed to the plurality of wireless communication terminals are buffered. A first step in which the wireless base station transmits the beacon to the plurality of wireless communication terminals; and the plurality of wireless communication terminals analyze the TIM field and a communication frame addressed to itself is transmitted to the wireless base station. A second step of making a transmission request to the radio base station, in which the radio communication terminal has a higher priority than the other terminal in the second step. When the communication frame is buffered in the radio base station, a communication sequence with the radio base station is not started for a certain period of time.

  A wireless communication system according to a third aspect of the present invention includes a wireless base station that transmits a beacon at regular intervals, and a plurality of wireless communication terminals that operate in a mode that allows intermittent wireless communication with the wireless base station. Are provided. The beacon includes a TIM field indicating that communication frames addressed to the plurality of wireless communication terminals are buffered. When the wireless base station buffers communication frames for different wireless communication terminals, the TIM field of the beacon indicating that only the communication frames for the wireless communication terminal having the highest priority is buffered is set. In the first step of transmitting to the plurality of wireless communication terminals, and when the plurality of wireless communication terminals analyze the TIM field and a communication frame addressed to itself is buffered in the wireless base station And a second step of making a transmission request to the radio base station.

  According to the first aspect of the present invention, a wireless communication system includes: a wireless base station that transmits a beacon at regular intervals; and a first wireless communication terminal that operates in a mode in which wireless communication with the wireless base station is always possible. And a second wireless communication terminal that operates in a mode capable of intermittent wireless communication with the wireless base station. The beacon transmitted by the radio base station is received as the first step, the TIM field of the beacon is analyzed as the second step, and the beacon addressed to the second radio communication terminal that operates in a mode capable of intermittent radio communication with the radio base station. Request transmission when communication frames are buffered. At this time, if it is confirmed that the communication frame addressed to the second wireless communication terminal that operates in a mode capable of intermittent wireless communication with the wireless base station is buffered in the wireless base station, the wireless base station is always wireless By controlling so that the communicable first wireless communication terminal does not start the communication sequence for a certain period of time, the timing of the transmission request of the second wireless communication terminal that operates in a mode in which wireless communication with the wireless base station can be intermittently performed is performed. It is possible to avoid delay as much as possible.

  Furthermore, wireless communication with the wireless base station is possible intermittently by transmitting as early as possible without delaying the timing of the transmission request of the second wireless communication terminal operating in a mode in which wireless communication with the wireless base station can be performed intermittently. The second wireless communication terminal operating in the correct mode can shorten the time required for communication in order to receive the communication frame buffered in the wireless base station, and can reduce power consumption. You can extend the time.

  According to the second aspect of the present invention, the wireless communication system includes a wireless base station that transmits a beacon at regular intervals, and a plurality of wireless devices that operate in a mode in which wireless communication with the wireless base station can be performed intermittently. A communication terminal. A beacon transmitted as a first step is received, and a transmission request is made when a communication frame addressed to the own terminal is buffered as a second step. At this time, if it is confirmed by the TIM field of the beacon that a communication frame addressed to a different wireless communication terminal operating in a mode capable of intermittent wireless communication with the wireless base station is buffered in the wireless base station, the wireless base station In accordance with a predetermined priority, control is performed so that a wireless communication terminal with a low priority does not start a communication sequence for a certain period of time, so that different wireless communication terminals operating in a mode in which wireless communication can be performed intermittently request transmission at the same timing. It is possible to prevent the transmission request timing of the radio communication terminal with a high priority from being delayed as much as possible.

  In addition, a transmission request from a high-priority wireless communication terminal that operates in a mode that allows intermittent wireless communication with the wireless base station can be transmitted as early as possible without receiving a communication frame buffered in the wireless base station. Therefore, it is possible to shorten the time for which communication is possible, reduce power consumption, and extend the usage time of the terminal.

  According to the third aspect of the present invention, the radio communication system includes a radio base station that transmits a beacon at regular intervals, and a plurality of radios that operate in a mode that allows intermittent radio communication with the radio base station. A communication terminal. When communication frames addressed to different wireless communication terminals operating in a mode capable of intermittent wireless communication with the wireless base station are buffered, the priority is high according to the priority of the wireless communication terminal predetermined by the wireless base station. A first step of controlling to set the TIM field of the beacon so that only communication frames addressed to the wireless communication terminal are buffered, and a plurality of wireless communication terminals request transmission when communication frames addressed to the own terminal are buffered And the second step of performing the transmission can prevent different wireless communication terminals operating in a mode capable of intermittent wireless communication with the wireless base station from requesting transmission at the same timing, and The transmission request timing can be minimized.

  Furthermore, communication is performed in order to receive a communication frame buffered in the radio base station by transmitting the transmission request of a high-priority wireless communication terminal operating in a mode capable of intermittent wireless communication as early as possible without delaying the transmission request as much as possible. It is possible to shorten the time for enabling, reduce power consumption, and extend the use time of the terminal.

<A. Embodiment 1>
<A-1. Configuration>
The present invention envisions a wireless communication system configured in an IEEE 802.11 infrastructure mode. In this type of system, wireless base stations (APs, access points) transmit beacons at predetermined intervals to control wireless communication terminals in the wireless network.

  FIG. 8 shows a configuration example of the wireless communication terminal according to Embodiment 1 of the present invention in the above-described wireless communication system. The wireless communication terminal 810 includes a communication unit 801, a control unit 802, and a frame processing unit 803.

  The communication unit 801 receives a frame signal from another wireless communication terminal and transmits a communication frame generated in the own terminal. The control unit 802 is connected to the communication unit 801 and the frame processing unit 803, and performs communication procedure control based on the communication protocol, communication frame transmission / reception processing control, power control, and the like. The frame processing unit 803 is connected to the communication unit 801 and the control unit 802, and performs processing such as analysis of a received communication frame and generation of a communication frame to be transmitted.

  Also, FIG. 9 shows a configuration example of the radio base station in the first embodiment of the present invention in the radio communication system. The radio base station 910 includes a communication unit 901, a control unit 902, a frame processing unit 903, and a frame storage unit 904.

  The communication unit 901 receives a frame signal from another terminal and transmits a communication frame generated in the own terminal. The control unit 902 is connected to each of the communication unit 901, the frame processing unit 903, and the frame storage unit 904, and performs control of a communication procedure based on a communication protocol, control of communication frame transmission / reception processing, and the like. The frame processing unit 903 is connected to each of the communication unit 901, the control unit 902, and the frame storage unit 904, and analyzes received communication frames, management / control frames in the network such as beacons, and other communication frame generation processing In addition, when a frame addressed to the wireless communication terminal in the power saving mode is received, processing such as transmitting the frame to the frame storage unit 904 is performed. The frame storage unit 904 is connected to the control unit 902 and the frame processing unit 903, buffers frames addressed to the wireless communication terminal in the power saving mode, and finishes transmitting the frame to the wireless communication terminal, or when a certain period of time elapses. Processing such as erasing the buffered frame is performed.

<A-2. Operation>
In IEEE 802.11, the active mode and the power saving mode are defined as the modes of the wireless communication terminal, and the wireless communication terminal in the active mode as the first wireless communication terminal is always in a state capable of transmitting and receiving communication frames. Yes, the wireless communication terminal in the power saving mode as the second wireless communication terminal cannot transmit / receive a communication frame, but can perform transmission / reception of frames in a Doze state that operates with low power consumption, but has more power than the Doze state. The operation that repeats the awake state that consumes the power is performed.

  On the other hand, the wireless base station knows whether the wireless communication terminal connected to its own network is operating in the power saving mode or the active mode, and communication to the wireless communication terminal in the power saving mode is performed. When the frame is buffered and a PS-Poll frame as a transmission request is received from a wireless communication terminal in the power saving mode, the buffered communication frame is transmitted to the wireless communication terminal. The radio base station transmits beacons at a predetermined interval, and the beacon includes a TIM field indicating that a communication frame addressed to the radio communication terminal in the power saving mode is buffered.

  The wireless communication terminal in the power saving mode described above determines whether the communication frame addressed to itself is buffered in the wireless base station, for example, once every several beacon periods from the wireless base station. The Awake state is entered at the timing when the beacon is transmitted.

  FIG. 2 shows the time lag of the Awake state when the transmission timing of the PS-Poll frame of the wireless communication terminal in the power saving mode is delayed due to the transmission of the communication frame of another wireless communication terminal in Embodiment 1 of the present invention. It is a figure explaining and shows the flow of the frame transmission operation | movement of each terminal.

  AP1 is a radio base station, STA1 and STA2 are radio communication terminals in the radio network belonging to AP1, and STA1 is operating in the power saving mode. The horizontal axis indicates the flow of time, and the TIM field of the beacon 201 is set to indicate that a communication frame for STA1 is buffered in AP1. The communication frame 202 addressed to STA1 is buffered in AP1. In FIG. 2, the PS-Poll frame 204 is transmitted with a delay of p21 hours from the transmission timing of the PS-Poll frame 203 that has not been transmitted. The ACK frame 205 is a response to the communication frame 202 addressed to STA1, and the communication frame 206 is transmitted from STA2.

  The STA1 confirms that the communication frame addressed to itself is buffered in the AP1 by the TIM field of the beacon 201 and tries to transmit the PS-Poll frame 203 at the timing of t21, but the STA2 transmits the communication frame 206. As a result, the STA1 cannot transmit the PS-Poll frame 203 at the timing of t21, enters the transmission waiting state for p21 time, transmits the PS-Poll frame 204 at the timing of t22, and then the communication frame 202 is transmitted from the AP1 to the STA1. Indicates that it is being sent. Since STA1 enters the Awake state at the timing of receiving the beacon 201 and remains in the Awake state until the communication frame 202 buffered in AP1 is received, if the transmission of the PS-Poll frame is shifted by p21 hours, The time is also increased by p21 hours, resulting in an increase in power consumption.

  As means for solving this problem, the operation of the wireless communication system according to Embodiment 1 of the present invention will be described with reference to FIG. 1 and FIG. What is described below is an operation for controlling the wireless communication terminal in the active mode not to start a communication sequence of frame transmission for a certain time when a communication frame addressed to the wireless communication terminal in the power saving mode is buffered in the wireless base station. It is.

  FIG. 1 is a diagram illustrating a flow of frame transmission of a radio base station and a radio communication terminal in a radio communication system, and FIG. 4 is a diagram illustrating an operation flow when a beacon is received by a radio communication terminal in an active mode. AP1 is a radio base station, STA1 and STA2 are radio communication terminals in the radio network belonging to AP1, STA1 as the second radio communication terminal is in the power saving mode, and STA2 as the first radio communication terminal is in the active mode. It is assumed that it is operating.

  In FIG. 1, the horizontal axis indicates the flow of time, and it is assumed that the TIM field of the beacon 101 is set to indicate that a communication frame for STA1 is buffered in AP1. The communication frame 102 for STA1 buffered in AP1 is shown in the TIM field described above.

  First, as a first step, a beacon 101 is transmitted to STA1 and STA2. Next, as a second step, the STA1 and STA2 analyze the TIM field of the beacon 101 and confirm whether a communication frame addressed to the wireless communication terminal in the power saving mode is buffered in the wireless base station. When it is confirmed that the buffer is buffered, the PS-Poll frame 103 as a transmission request is transmitted from the STA1, and when the communication frame 102 for the STA1 is transmitted from the AP1, the ACK frame 104 is transmitted as a response to the communication frame 102. Is done.

  On the other hand, the STA2 does not transmit at the transmission timing of the communication frame 105, but transmits the communication frame 106 after a certain time. It is assumed that STA1 enters an Awake state for receiving a beacon at the timing when the beacon 101 is transmitted.

  When AP1 transmits beacon 101 and STA1 and STA2 receive beacon 101, it can be confirmed that the communication frame addressed to STA1 is buffered in AP1 by the TIM field of beacon 101. Therefore, STA1 follows the wireless communication sequence. When it is confirmed that the wireless medium is unused for the sum of the DIFS time and the random backoff time from the timing of transmission completion t11 of the beacon 101, the PS-Poll frame 103 is transmitted.

  As shown in FIG. 4, when the transmission request for the communication frame 105 is generated in the STA2 before the STA1 transmits the PS-Poll frame, the STA2 performs the beacon 101 in the communication unit 801 illustrated in FIG. And the frame processing unit 803 analyzes the TIM field as the first process (step S401). Next, it is determined whether or not a communication frame addressed to STA1 is buffered in AP1 (step S402).

  Next, as the second process, the communication unit 801 and the frame processing unit 803 are controlled by the control unit 802 shown in FIG. 8, and the DIFS time and the maximum random backoff time are set so as not to inhibit the transmission of the PS-Poll frame 103. Control is performed so that the communication sequence is not started for the sum p11 time (step S403).

  As shown in FIG. 1, when a PS-Poll frame 103 is transmitted from STA1 and received by AP1, AP1 transmits a buffered communication frame 102 to STA1 after SIFS time. When STA1 normally receives the communication frame 102, it transmits an ACK frame 104 to AP1 after SIFS time, and confirms that the communication frame addressed to STA1 is not buffered in AP1 by the More Data field or the More Fragments field of the communication frame 102. STA1 enters the Doze state again. Since AP1 sets the time until transmission of the ACK frame 104 is completed in the header of the communication frame 102, the STA2 cannot start the communication sequence until the transmission of the ACK frame 104 is completed. After confirming that the wireless medium is unused, the communication frame 106 is transmitted after the completion of the transmission. In step S402, when there is no communication frame addressed to the wireless communication terminal operating in the power saving mode in the wireless base station, the communication frame is transmitted according to the normal communication sequence without waiting for p11 time.

  Here, the non-transmission period p11 of the communication frame in STA2 will be described. In IEEE 802.11, PS-Poll frames can be transmitted after the sum of the DIFS time and the random backoff time from the timing when the wireless medium is not used. Therefore, the PS-Poll frame is not delayed as much as possible. Since it is necessary to prevent the communication sequence of other communication frames from being performed after the transmission of the beacon, it is necessary to prevent the communication sequence of other communication frames from being performed as the sum of the DIFS time and the specified maximum random backoff time. Is the sum of the maximum random backoff times. After the transmission of the PS-Poll frame is completed, the transmission timing of the frame transmitted from AP1 and the ACK frame that is the response is the SIFS time. Since the SIFS time is shorter than the DIFS time, the time until STA1 transmits the ACK frame. Communication is not hindered by terminals in the network until the communication sequence is completed. As described above, for all wireless communication terminals operating in the active mode in the network belonging to AP1, it was confirmed that communication frames addressed to the wireless communication terminals operating in the power saving mode are buffered by the TIM field of the beacon. In such a case, by controlling so as not to start the p11 time communication sequence that is the sum of the DIFS time and the specified maximum random backoff time, the wireless communication terminal operating in the power saving mode can delay the PS-Poll frame as much as possible. It becomes possible to transmit at an early timing.

<A-3. Effect>
According to the first embodiment of the present invention, the radio communication system operates in a radio base station 910 that transmits a beacon 101 at regular intervals, and in a mode (active mode) in which radio communication with the radio base station 910 is always possible. STA2 serving as a first wireless communication terminal, and STA1 serving as a second wireless communication terminal operating in a mode (power saving mode) capable of intermittent wireless communication with the wireless base station 910. When the wireless base station 910 transmits a beacon as the first step, the STA1 and STA2 receive the beacon 101, and the communication frame addressed to the STA1 is buffered as the second step, the wireless communication terminal STA1 in the power saving mode Transmits the PS-Poll frame 103 as a transmission request. At this time, when the wireless communication terminal STA2 in the active mode analyzes the TIM field of the beacon 101 and confirms that the communication frame addressed to the wireless communication terminal in the power saving mode is buffered in the wireless base station 910, By controlling so that the wireless communication terminal in the active mode does not start the communication sequence for a certain time, the transmission timing of the PS-Poll frame 103 of the wireless communication terminal operating in the power saving mode can be prevented from being delayed as much as possible.

  Further, a communication frame buffered in the radio base station 910 by the radio communication terminal STA1 operating in the power saving mode by transmitting the PS-Poll frame 103 of the radio communication terminal operating in the power saving mode as early as possible without delay. Since it is possible to shorten the time for entering the awake state for receiving 102 and reduce power consumption, the usage time of the terminal can be extended.

  Further, in the first embodiment, the wireless communication terminal STA2 in the active mode confirms that the communication frame 102 addressed to the wireless communication terminal operating in the power saving mode is buffered in the wireless base station 910 by the TIM field of the beacon 101. As the frame non-transmission period, the sum of the DIFS time and the maximum random back-off time is not limited to this, but is defined in the wireless network by the priority of the PS-Poll frame 103, etc. It is also possible to use AIFS time instead of a value, for example DIFS time.

  Further, according to the first embodiment of the present invention, the radio communication terminal operates in a mode in which radio communication with the radio base station 910 is always possible, and transmits / receives transmission / reception frames including the beacon 101 transmitted from the radio base station. A communication unit 801 that performs processing, a frame processing unit 803 that performs analysis and generation processing of the transmission / reception frame, and a control unit 802 that controls the communication unit 801 and the frame processing unit 803 are provided. As the first process, the frame processing unit 803 analyzes the TIM field to determine whether a communication frame addressed to the STA 1 is buffered in the radio base station 910, and the control unit 802 performs the first process. When a communication frame addressed to the radio communication terminal STA1 operating in a mode capable of intermittent radio communication with the radio base station 910 is buffered in the radio base station 910, communication with the radio base station 910 is performed for a certain period of time. A second process for controlling the communication unit and the frame processing unit is executed so as not to start the sequence. Thereby, the transmission timing of the PS-Poll frame 103 of the wireless communication terminal operating in the power saving mode can be minimized.

<B. Second Embodiment>
<B-1. Configuration>
The configuration of the radio communication system according to the second embodiment includes the radio base station and radio communication terminals that operate in a plurality of power saving modes in the first embodiment. In the second embodiment, it is assumed that priorities are determined in advance for each wireless communication terminal by an appropriate method.

<B-2. Operation>
3 and 5, the radio base station determines when communication frames addressed to different radio communication terminals operating in the power saving mode are buffered in the radio base station in Embodiment 2 of the present invention. An operation for controlling a wireless communication terminal having a low priority so as not to start a communication sequence of frame transmission for a certain time according to the priority will be described.

  FIG. 3 is a diagram showing a flow of frame transmission of the radio base station and the radio communication terminal in the radio communication system, and FIG. 5 is a diagram showing an operation flow when the beacon is received by the radio communication terminal in the power saving mode. . AP1 is a radio base station, STA1 and STA2 are radio communication terminals in the radio network belonging to AP1, and STA1 and STA2 are operating in the power saving mode.

  In FIG. 3, it is assumed that STA1 is a high-priority wireless communication terminal and STA2 is a low-priority wireless communication terminal. The horizontal axis indicates the flow of time, and the TIM field of the beacon 301 is set to indicate that communication frames for STA1 and STA2 are buffered in AP1.

  First, as a first step, a beacon 301 is transmitted to STA1 and STA2. Next, as a second step, STA1 and STA2 analyze the TIM field of beacon 301 and confirm whether a communication frame addressed to itself is buffered in the radio base station. After confirmation, a PS-Poll frame 304 is transmitted as a transmission request. When STA2 tries to transmit PS-Poll frame 306 as a transmission request, STA2 confirms that communication frame 302 addressed to STA1 having a high priority is buffered, and PS-Poll frame 306 that has not been transmitted. The PS-Poll frame 307 is transmitted after a certain time from the transmission timing. Thereafter, an ACK frame 305 is transmitted as a response to the communication frame 302, and an ACK frame 308 is transmitted as a response to the communication frame 303. In addition, STA1 and STA2 which operate | move in a power saving mode shall be in an Awake state in order to receive the beacon 301 at the timing at which the beacon 301 is transmitted.

  As for the priority of each wireless communication terminal in each power saving mode, for example, there is a method in which the user prioritizes each wireless communication terminal in advance and sets it in the wireless base station. Alternatively, there is a method of checking the battery state of the wireless communication terminal and setting the priority in ascending order of the remaining battery level. Regarding the confirmation of the battery state, for example, each wireless communication terminal periodically checks the battery state, transmits a communication frame including the battery state to the wireless base station, and receives the battery state of each wireless communication terminal received by the wireless base station. There is a method of setting the priority order of the wireless communication terminals based on the above, and periodically notifying each wireless communication terminal of the set priority order. The battery status uses values such as the percentage of remaining battery power and the estimated operating time of the battery, for example, to increase the priority of wireless communication terminals with low battery power, or to perform wireless communication with short battery operating time The priority is set by increasing the priority of the terminal.

  As shown in FIG. 5, when the wireless communication terminal operates as shown in FIG. 5, AP1 transmits a beacon 301, and when the communication unit 801 shown in FIG. 8 of STA1 and STA2 receives the beacon 301, the frame processing unit 803 receives the TIM field of the beacon 301. Is analyzed (step S501).

  Next, STA1 and STA2 confirm whether or not a communication frame addressed to itself is buffered in AP1 (step S502).

  Further, it is confirmed whether or not a communication frame addressed to a wireless communication terminal in a power saving mode other than itself is buffered in AP1 (step S503).

  Since the TIM field of the beacon 301 shown in FIG. 3 is set to indicate that AP1 is buffering communication frames addressed to both wireless communication terminals STA1 and STA2, STA1 and STA2 have their own terminal priority. Check the degree. In the state of FIG. 3, since STA1 is set to have a higher priority than STA2 (step S504), STA1 follows the radio communication sequence from the timing of transmission completion time t31 of beacon 301 to the DIFS time and the random back. The frame processing unit 803 shown in FIG. 8 generates a PS-Poll frame 304 as a transmission request frame as a first process after confirming that the wireless medium is unused for the sum of the off times, and the communication unit 801 transmits a PS-Poll frame as the second process.

  When the PS-Poll frame 304 is received by AP1, AP1 transmits the buffered communication frame 302 to STA1 after SIFS time. When STA1 receives communication frame 302 normally, ACK frame 305 is transmitted to AP1 after SIFS time (step S506), and the communication frame addressed to STA1 is not buffered in AP1 by the More Data field or More Fragments field of communication frame 302. When this is confirmed, STA1 enters the Doze state again.

  Further, STA2 requests transmission of the PS-Poll frame 306, but since the priority is set to be lower than STA1 (step S504), the control unit 802 shown in FIG. 8 sets the communication unit 801 and the frame processing unit 803. The communication sequence is not started for p31 time which is the sum of the DIFS time and the maximum random backoff time so as not to inhibit the transmission of the PS-Poll frame 304 of STA1 (step S505).

  Since AP1 sets the time until transmission of the ACK frame 305 is completed in the header of the communication frame 302, the STA2 cannot start the communication sequence until the ACK frame 305 has been transmitted. After the transmission is completed, it is confirmed that the wireless medium is unused for the sum of the DIFS time and the random backoff time, and the PS-Poll frame 307 is transmitted. When the PS-Poll frame 307 is received by the AP 1 After SIFS time, AP1 transmits the buffered communication frame 303 to STA2. When STA2 receives communication frame 303 normally, ACK frame 308 is transmitted to AP1 after SIFS time (step S506), and the frame addressed to STA2 is not buffered in AP1 by the More Data field or the More Fragments field of communication frame 303. When STA2 is confirmed, STA2 enters the Doze state again.

  In step S502, if there is no frame addressed to itself, the STA shifts from the awake state to the doze state in order to reduce power consumption. In step S503, if a communication frame addressed to a wireless communication terminal in a power saving mode other than its own terminal is not buffered, it is not necessary to wait for transmission of a PS-Poll frame from another wireless communication terminal. Regardless of this, the PS-Poll is transmitted to the AP according to the normal sequence, and the buffered communication frame is received. Note that the untransmitted time p31 is the sum of the DIFS time and the specified maximum random backoff time, similar to the untransmitted time p11 in the first embodiment.

<B-3. Effect>
According to the second embodiment, the wireless communication system operates in a wireless base station that transmits a beacon 301 at regular intervals, and in a mode that allows intermittent wireless communication with the wireless base station, that is, in a power saving mode. STA1 and STA2 as a plurality of operating wireless communication terminals are provided. The beacon 301 transmitted as the first step is received, and it is confirmed that the communication frame addressed to the different wireless communication terminal operating in the power saving mode is buffered in the wireless base station by the TIM field of the beacon as the second step. Request transmission. At this time, different wireless communication terminals operating in the power saving mode transmit at the same timing by controlling so that the wireless communication terminals with lower priority do not start the communication sequence for a certain period of time according to the priority determined in advance by the wireless base station. It is possible to prevent the transmission of the PS-Poll frame 306 as a request, and it is possible to prevent the transmission timing of the PS-Poll frame 304 of the high-priority wireless communication terminal from being delayed as much as possible.

  Further, the PS-Poll frame 304 of the high-priority wireless communication terminal operating in the power saving mode is transmitted as early as possible so as not to delay as much as possible, so that the communication frame buffered in the wireless base station can be received. Time can be shortened and power consumption can be reduced. For example, if the priority of a terminal with a low battery level is set high as the priority of a wireless communication terminal, the consumption of a terminal with a low battery level can be reduced. Power can be reduced and the usage time of the terminal can be extended.

  Also in the second embodiment, as in the first embodiment, the communication frame addressed to the wireless communication terminal operating in the power saving mode is buffered in the wireless base station by the wireless communication terminal in the active mode using the TIM field of the beacon 301. As a frame non-transmission period when it is confirmed that the frame is transmitted, the sum of the DIFS time and the maximum random back-off time is used. However, the present invention is not limited to this, and depending on the priority of the PS-Poll frame, the wireless network It is also possible to use AIFS time instead of the value defined in the above, for example, DIFS time.

  In addition, the priority is determined by the STA1 and STA2 as the plurality of wireless communication terminals detecting the remaining operating battery power of the terminal, and transmitting a communication frame including the remaining battery power to the wireless base station at regular intervals. The wireless base station receives a communication frame including the remaining battery level transmitted from, for example, STA1 and STA2, and determines the order based on the received communication frame including the remaining battery level. Communication frames can be transmitted to the wireless communication terminal, and the power consumption of the wireless communication system can be further suppressed.

  Further, according to the second embodiment, the wireless communication terminal operates in a mode that allows intermittent wireless communication with a wireless base station, and performs transmission / reception processing of a transmission / reception frame including a beacon transmitted from the wireless base station. The communication unit 801 includes a frame processing unit 803 that performs analysis and generation processing of the transmission / reception frame, and a control unit 802 that controls the communication unit and the frame processing unit. As a first process, the frame processing unit 803 analyzes the TIM field, and when a communication frame addressed to itself is buffered in the radio base station, a PS as a transmission request frame of the communication frame is sent to the radio base station. A -Poll frame is generated, and as a second process, the communication unit 801 transmits the PS-Poll frame to the radio base station. At this time, a communication frame addressed to another radio communication terminal operating in a mode capable of intermittent radio communication with the radio base station is buffered in the radio base station, and the other radio communication terminal has a predetermined priority. When the degree is higher than that of the terminal itself, the control unit 802 controls the communication unit 801 and the frame processing unit 803 so as not to start a communication sequence with the radio base station for a certain period of time. In addition, it is possible to prevent the transmission timing of the PS-Poll frame of a high-priority wireless communication terminal from being delayed as much as possible.

<C. Embodiment 3>
<C-1. Configuration>
As in the case of the second embodiment, the configuration of the radio communication system according to the third embodiment includes the radio base station in the first embodiment and a radio communication terminal that operates in a plurality of power saving modes. . Also in the third embodiment, it is assumed that priorities are determined in advance for each wireless communication terminal by an appropriate method.

<C-2. Operation>
Using FIG. 6 and FIG. 7, when a communication frame addressed to a different wireless communication terminal operating in the power saving mode is buffered in the wireless base station in Embodiment 3 of the present invention, the wireless base station determines The operation of setting the TIM field of the beacon so as to indicate that the communication frame for only the wireless communication terminal with the highest priority is buffered according to the priority will be described.

  FIG. 6 is a diagram illustrating a flow of frame transmission of the radio base station and the radio communication terminal in the radio communication system, and FIG. 7 is an operation flow at the time of beacon transmission of the radio base station. AP1 is a radio base station, STA1 and STA2 are radio communication terminals in the radio network belonging to AP1, and STA1 and STA2 are operating in the power saving mode. Further, STA1 is a high-priority wireless communication terminal and STA2 is a low-priority wireless communication terminal.

  In FIG. 6, the horizontal axis indicates the flow of time. At the time when the beacon 601 is transmitted, the communication frame for STA1 and STA2 is buffered in AP1 at AP1, but the TIM field of beacon 601 contains only the communication frame for STA1. Assume that it is set to indicate that it is buffered in AP1.

  As a first step, a beacon 601 whose TIM field is set to indicate that only communication frames for STA1 are buffered in AP1 is transmitted from the radio base station to STA1 and STA2, STA1 knows that the communication frame addressed to itself is buffered in AP1, and transmits PS-Poll frame 605. On the other hand, a communication frame 602 for STA1 in which AP1 is buffered is transmitted to STA1. The STA1 transmits an ACK frame 606 as a response to the communication frame 602.

  In addition, when the beacon 603 in which the TIM field is set to indicate that only the communication frame for STA2 is buffered in AP1, STA2 transmits the communication frame addressed to its own terminal to AP1. It can be seen that it is buffered, and a PS-Poll frame 607 is transmitted. In response to this, the communication frame 604 for STA2 in which AP1 is buffered is transmitted to STA2. The STA2 transmits an ACK frame 608 as a response to the communication frame 604.

  STA1 and STA2 are in the Awake state to receive the beacon 601 at the timing when the beacon 601 is transmitted, and STA2 is in the Awake state to receive the beacon 603 at the timing when the beacon 603 is transmitted And Note that the priorities of the wireless communication terminals in each power saving mode are the same as those described in the second embodiment, and the description thereof is omitted for the sake of brevity.

  On the other hand, with respect to the operation of the radio base station, as shown in FIG. 7, AP1 buffers communication frames addressed to a plurality of power saving mode radio communication terminals in the frame storage unit 904 shown in FIG. It is confirmed whether it is (step S701).

  At the time of transmitting the beacon 601 in FIG. 6, since the communication frames addressed to the plurality of wireless communication terminals STA1 and STA2 are buffered, the wireless base station compares the priorities of STA1 and STA2, and determines the highest priority. The control unit 902 shown in FIG. 9 controls the frame processing unit 903 and the communication unit 901 to set the TIM field so as to indicate that only communication frames for the STA1, which is a high terminal, are buffered (step S702). .

  In step S701, when a communication frame addressed to a power saving mode wireless communication terminal is not buffered, or only a communication frame addressed to one power saving mode wireless communication terminal, for example, a communication frame addressed to STA2, is buffered. The normal beacon setting operation is performed (step S703). That is, when the communication frame addressed to the power saving mode wireless communication terminal is not buffered, the setting indicating that the communication frame addressed to the power saving mode wireless communication terminal is buffered is not performed in the TIM field. When only the communication frame addressed to the wireless communication terminal in the power saving mode is buffered, for example, when only the communication frame addressed to STA2 is buffered, the communication frame addressed to STA2 is buffered in the TIM field of the beacon. Set to indicate.

  After setting the TIM field of the beacon, AP1 transmits a beacon 601 (step S704). When STA1 and STA2 receive the beacon 601, only the communication frame addressed to STA1 is buffered in AP1 in the TIM field of beacon 601. Since the STA2 PS-Poll frame is not transmitted, the STA1 is in a state in which the wireless medium is unused from the beacon transmission completion time t61 to the sum of the DIFS time and the random backoff time. After confirming that there is a PS-Poll frame 605, when the PS-Poll frame 605 is received by the AP1, the AP1 transmits the buffered communication frame 602 to the STA1 after SIFS time. When STA1 normally receives the communication frame 602, it transmits an ACK frame 606 to AP1 after SIFS time, and confirms that the communication frame addressed to STA1 is not buffered in AP1 by the More Data field or the More Fragments field of the communication frame 602. STA1 enters the Doze state again.

  After transmitting the communication frame addressed to STA1, since the communication frame addressed to STA2 is still buffered in AP1, the TIM field of beacon 603 is set to indicate that the communication frame addressed to STA2 is buffered. 603 is transmitted. When STA2 receives the beacon 603, it can be confirmed that the communication frame addressed to STA2 is buffered in AP1 in the TIM field of the beacon 603. After confirming that the wireless medium is unused for the sum time, the PS-Poll frame 607 is transmitted, and when the PS-Poll frame 607 is received by AP1, the communication frame that AP1 has buffered after SIFS time 604 is transmitted to STA2. When STA1 normally receives the communication frame 604, it transmits an ACK frame 608 to AP1 after SIFS time, and confirms that the communication frame addressed to STA2 is not buffered in AP1 by the More Data field or the More Fragments field of the communication frame 604. STA2 enters the Doze state again.

<C-3. Effect>
According to the third embodiment, the radio communication system includes a radio base station that transmits a beacon at regular intervals, and a plurality of modes that operate in a mode (power saving mode) in which radio communication with the radio base station can be intermittently performed. A wireless communication terminal. As a first step, when communication frames addressed to different wireless communication terminals operating in the power saving mode are buffered in the wireless base station, the priority is high according to the priority of the wireless communication terminal determined in advance by the wireless base station. Set the beacon's TIM field so that only communication frames addressed to the wireless communication terminal are buffered, and in the second step, a plurality of wireless communication terminals have determined that communication frames addressed to themselves are buffered. Request to send in case. Accordingly, it is possible to prevent different wireless communication terminals operating in the power saving mode from transmitting PS-Poll frames at the same timing, and delay the transmission timing of PS-Poll frames of high-priority wireless communication terminals as much as possible. You can avoid it.

  Further, the PS-Poll frame of the high-priority wireless communication terminal that operates in the power saving mode is transmitted as early as possible without delaying the PS-Poll frame, so that the communication frame buffered in the wireless base station is received. The time can be shortened and the power consumption can be reduced. For example, if the priority of a terminal with a low battery level is set high as the priority of a wireless communication terminal, the power consumption of a terminal with a low battery level And the usage time of the terminal can be extended.

  In the description of the second embodiment and the third embodiment, the case where only the wireless communication terminal in the power saving mode exists as the wireless communication terminal configuring the wireless network is described. However, the present invention is not limited to this configuration. For example, when there is a wireless communication terminal in the active mode, as described in the first embodiment, when a beacon is received, a communication addressed to the wireless communication terminal in the power saving mode is transmitted to the wireless base station by the TIM field of the beacon. When it is confirmed that there is a frame, the wireless communication terminal in the active mode is controlled by the wireless network in the active mode by controlling so as not to start the communication sequence of frame transmission for the sum of the DIFS time and the maximum random backoff time from the beacon transmission timing. Even if it exists in the wireless communication terminal of the power saving mode with the highest priority The transmission timing of the S-Poll frame can be prevented from being delayed as much as possible. By transmitting the PS-Poll frame as early as possible without delaying as much as possible, the Awake state is used to receive the communication frame buffered in the radio base station. Can be shortened and power consumption can be reduced.

  Further, according to the third embodiment, the radio base station performs communication processing of a transmission / reception frame including a beacon with a plurality of wireless communication terminals that are intermittently capable of wireless communication (power saving mode), and A frame storage unit 904 for buffering communication frames addressed to the plurality of wireless communication terminals, a frame processing unit 903 for analyzing and generating the transmission / reception frame, and a control for controlling the communication unit and the frame processing unit Part 902. The beacon 601 includes a TIM field indicating that a communication frame addressed to the wireless communication terminal is buffered in the frame storage unit 904, and a communication frame addressed to a different wireless communication terminal is buffered in the frame storage unit 904 In this case, the control unit 902 sets and transmits the TIM field of the beacon 601 indicating that only the communication frame for the wireless communication terminal having the highest predetermined priority is buffered in the frame storage unit 904. As described above, by controlling the frame processing unit 903 and the communication unit 901, the PS-Poll frame of the wireless communication terminal in the power saving mode having the highest priority even when the wireless communication terminal in the active mode exists in the wireless network. To avoid delaying transmission timing as much as possible Can, by sending quickly without delaying possible PS-Poll frame, it is possible to shorten the time during which the Awake state to receive the communication frame buffered in the radio base station to reduce power consumption.

  Also, the priority is that the plurality of wireless communication terminals detect the remaining operating battery power of the terminal, and transmit a communication frame including the remaining battery power to the wireless base station at regular intervals. By receiving a communication frame including the remaining battery level transmitted from a plurality of wireless communication terminals and making a determination based on the received communication frame including the remaining battery level, the wireless base station has a higher priority wireless communication terminal. It is possible to transmit a communication frame to.

It is a figure which shows the outline | summary of the frame transmission operation | movement of the radio base station and radio | wireless communication terminal in Embodiment 1 of this invention. In an embodiment of the present invention, it is a figure explaining time gap of the Awake state of a wireless communication terminal of a power saving mode when transmission timing of a PS-Poll frame is delayed. It is a figure which shows the outline | summary of the frame transmission operation | movement of the radio base station and radio | wireless communication terminal in Embodiment 2 of this invention. It is a figure which shows the operation | movement flow at the time of the beacon reception of the radio | wireless communication terminal of the active mode in Embodiment 1 of this invention. It is a figure which shows the operation | movement flow at the time of the beacon reception of the radio | wireless communication terminal of the power saving mode in Embodiment 2 of this invention. It is a figure which shows the outline | summary of the frame transmission operation | movement of the radio base station and radio | wireless communication terminal in Embodiment 3 of this invention. It is a figure which shows the operation | movement flow at the time of the beacon transmission of the wireless base station in Embodiment 3 of this invention. It is a figure which shows the structural example of the radio | wireless communication terminal in embodiment of this invention. It is a figure which shows the structural example of the wireless base station in embodiment of this invention.

Explanation of symbols

  101, 201, 301, 601, 603 Beacon, 102, 202, 302, 303, 602, 604 Buffered communication frame, 103, 204, 304, 307, 605, 607 PS-Poll frame, 104, 205, 305 , 308, 606, 608 ACK frame, 105 communication frame not transmitted, 106, 206 communication frame, 203, 306 PS-Poll frame not transmitted, 801, 901 communication unit, 802, 902 control unit, 803, 903 Frame processing unit, 810 wireless communication terminal, 904 frame storage unit, 910 wireless base station.

Claims (8)

A wireless base station that transmits a beacon at regular intervals;
A first wireless communication terminal that operates in a mode capable of always wireless communication with the wireless base station;
A second wireless communication terminal that operates in a mode capable of intermittent wireless communication with the wireless base station;
In a wireless communication system comprising:
The beacon includes a TIM (Traffic Indication Map) field indicating that a communication frame addressed to the second wireless communication terminal is buffered,
A first step in which the radio base station transmits the beacon to the first radio communication terminal and the second radio communication terminal;
A second step in which the second wireless communication terminal analyzes the TIM field and makes a transmission request to the wireless base station when a communication frame addressed to itself is buffered in the wireless base station; Prepared,
In the second step, the first wireless communication terminal analyzes the TIM field, and when the communication frame addressed to the second wireless communication terminal is buffered in the wireless base station, the wireless communication terminal performs the wireless communication for a certain period of time. Do not start the communication sequence with the base station,
Wireless communication system. A wireless base station that transmits a beacon at regular intervals;
A plurality of wireless communication terminals operating in a mode capable of intermittent wireless communication with the wireless base station;
In a wireless communication system comprising:
The beacon includes a TIM field indicating that communication frames addressed to the plurality of wireless communication terminals are buffered,
A first step in which the radio base station transmits the beacon to the plurality of radio communication terminals;
A plurality of wireless communication terminals that analyze the TIM field and request a transmission request to the wireless base station when a communication frame addressed to itself is buffered in the wireless base station; ,
In the second step, when a communication frame to another terminal having a predetermined priority higher than that of the own terminal is buffered in the wireless base station, the wireless communication terminal Do not start communication sequence,
Wireless communication system. A wireless base station that transmits a beacon at regular intervals;
A plurality of wireless communication terminals operating in a mode capable of intermittent wireless communication with the wireless base station;
In a wireless communication system comprising:
The beacon includes a TIM field indicating that communication frames addressed to the plurality of wireless communication terminals are buffered,
When the wireless base station buffers communication frames for different wireless communication terminals, the TIM field of the beacon indicating that only the communication frames for the wireless communication terminal having the highest priority is buffered is set. A first step of transmitting to the plurality of wireless communication terminals;
A plurality of wireless communication terminals that analyze the TIM field and make a transmission request to the wireless base station when a communication frame addressed to itself is buffered in the wireless base station; ,
Wireless communication system. The priority is determined by the plurality of wireless communication terminals detecting an operating battery remaining amount of the terminal and transmitting a communication frame including the remaining battery amount to the wireless base station at regular intervals. Receiving a communication frame including the remaining battery level transmitted from the wireless communication terminal, and determining based on the received communication frame including the remaining battery level,
The wireless communication system according to claim 2 or 3. A communication unit that operates in a mode capable of always wireless communication with a wireless base station, and performs a transmission / reception process of a transmission / reception frame including a beacon transmitted from the wireless base station;
A frame processing unit for analyzing and generating the transmission / reception frame;
A control unit that controls the communication unit and the frame processing unit;
In a wireless communication terminal comprising:
The beacon includes a TIM field indicating that a communication frame addressed to a wireless communication terminal operating in a mode capable of intermittent wireless communication with the wireless base station is buffered in the wireless base station;
The frame processing unit analyzes the TIM field to determine whether a communication frame addressed to a wireless communication terminal operating in a mode capable of intermittent wireless communication with the wireless base station is buffered in the wireless base station. The first process is performed,
When the communication frame addressed to the wireless communication terminal operating in a mode capable of intermittent wireless communication with the wireless base station is buffered in the wireless base station by the first process, Performing a second process for controlling the communication unit and the frame processing unit so as not to start a communication sequence with the radio base station;
Wireless communication terminal. A communication unit that operates in a mode in which wireless communication with a wireless base station can be intermittently performed, and performs transmission / reception processing of a transmission / reception frame including a beacon transmitted from the wireless base station;
A frame processing unit for analyzing and generating the transmission / reception frame;
A control unit that controls the communication unit and the frame processing unit;
In a wireless communication terminal comprising:
The beacon includes a TIM field indicating that a communication frame addressed to a wireless communication terminal operating in a mode capable of intermittent wireless communication with the wireless base station is buffered in the wireless base station;
The frame processing unit analyzes the TIM field and executes a first process of generating a transmission request frame of a communication frame for the radio base station when a communication frame addressed to the terminal is buffered in the radio base station And
The communication unit performs a second process of transmitting the transmission request frame to the radio base station,
In the second process, when the control unit transmits a transmission request frame to the radio base station, a communication frame addressed to another radio communication terminal operating in a mode in which the radio base station can intermittently communicate with the radio base station. Is not buffered in the radio base station, and the other radio communication terminal has a predetermined priority higher than its own terminal, the communication unit does not start a communication sequence with the radio base station for a certain period of time. And controlling the frame processing unit,
Wireless communication terminal. A plurality of wireless communication terminals that operate in a mode capable of wireless communication intermittently, a communication unit that performs transmission / reception processing of transmission / reception frames including beacons,
A frame storage unit for buffering communication frames addressed to the plurality of wireless communication terminals;
A frame processing unit for analyzing and generating the transmission / reception frame;
A control unit that controls the communication unit and the frame processing unit;
In a radio base station comprising:
The beacon includes a TIM field indicating that a communication frame addressed to the wireless communication terminal is buffered in the frame storage unit,
When a communication frame addressed to a different wireless communication terminal is buffered in the frame storage unit, the control unit buffers only the communication frame to the wireless communication terminal having the highest priority in the frame storage unit. Control the frame processing unit and the communication unit to set and transmit the TIM field of the beacon indicating
Radio base station. The priority is determined by the plurality of wireless communication terminals detecting an operating battery remaining amount of the terminal and transmitting a communication frame including the remaining battery amount to the wireless base station at regular intervals. Receiving a communication frame including the remaining battery level transmitted from the wireless communication terminal, and determining based on the received communication frame including the remaining battery level,
The radio base station according to claim 7.

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