JP5415592B2 - Wireless communication apparatus, terminal, communication control method, and communication program - Google Patents

Description

  Embodiments described herein relate generally to a wireless communication device, a terminal, a communication control method, and a communication program.

  The IEEE802.11 wireless LAN standard defines an infrastructure mode in which a wireless terminal connects to a wireless base station and communicates via the wireless base station. In addition, to reduce power consumption of the wireless terminal in the infrastructure mode The power saving function (power save mode) is defined (Non-patent Document 1). This is a function that realizes power saving on the wireless terminal side, not the wireless base station, and the wireless terminal transitions the wireless communication module to the sleep state in synchronization with the beacon signal periodically transmitted from the base station. This reduces power consumption. Since the wireless terminal that has entered the sleep state cannot receive data, the wireless base station temporarily buffers the data, and notifies the wireless terminal by including TIM (Traffic Indication Map) in the beacon signal. To do. The wireless terminal that has received the notification can receive the data from the wireless base station by polling the wireless base station.

On the other hand, Patent Document 1 discloses a method for reducing power consumption of a radio base station in an infrastructure mode. In general, a radio base station in the infrastructure mode needs to always wait for data transmission from a radio terminal that does not know when it occurs, and there is a problem that it cannot transition to a sleep state. In Patent Document 1, before a radio base station transitions to a sleep state, the radio base station transitions to a sleep state by transmitting a CTS (Clear To Send) frame that prohibits transmission of the radio terminal to the radio terminal. Has proposed.
IEEE Std. 802.11-2007, “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications” JP 2004-336401 A

  In the above-described prior art, each of the power saving function on the wireless terminal side and the power saving function on the wireless base station side is shown, but a method for operating both power saving functions simultaneously is not described. In recent years, mobile terminals such as notebook PCs (Personal Computers) and smartphones are becoming multi-interface (3G, WiMAX, Wi-Fi, etc.). In the future, mobile terminals will be set as wireless base stations and peripheral gadget devices (games) Devices, music players, etc.) are expected to be requested to access the Internet via mobile terminals. In such a configuration, both the radio base station and the radio terminal can be portable terminals having a finite battery. Therefore, it is important to simultaneously save power in both the radio base station and the radio terminal that constitute the infrastructure.

  As described above, the power saving function of the wireless terminal defined in Non-Patent Document 1 transmits and receives data at the timing when the wireless terminal cancels the sleep state. Therefore, in order to save power in the wireless terminal, it is desirable to shorten a period during which data can be transmitted and received and to ensure a long sleep state period. On the other hand, Patent Document 1 adopts a method of prohibiting data transmission of a wireless terminal, and transmits a CTS frame instructing prohibition using a mechanism of CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance). Therefore, since the fairness is maintained between the opportunity for the wireless terminal to transmit data and the opportunity for the wireless base station to transmit the CTS frame, the wireless terminal may receive the CTS frame before transmitting the data. . At this time, the wireless terminal cannot quickly transition to the sleep state, resulting in a problem that the power saving effect is reduced. Patent Document 1 proposes a control method that gives priority to an opportunity for a wireless terminal to transmit data by controlling a backoff time in a contention window. However, this priority control works only for the first transmission opportunity, and a wireless terminal that continuously transmits a plurality of data cannot avoid receiving a CTS frame before the transmission of the plurality of data is completed. Cannot transition to sleep state. Accordingly, there arises a problem that the power saving effect is similarly reduced.

  Embodiments of the present invention provide a wireless communication device, a terminal, a communication control method, and a communication program that simultaneously realize power saving with a wireless terminal.

  The wireless communication apparatus according to an aspect of the present invention includes means for transmitting a beacon including information related to a first period length, and from the transmission timing of the beacon, at least during the period of the first period length In the state, and after the elapse of the first period length, it is possible to transition to the second state until the next beacon transmission timing, and the power consumption of the wireless communication device in the second state is the first It is characterized by being smaller than the power consumption of the wireless communication device in the state of 1.

  The wireless communication apparatus as one aspect of the present invention includes means for transmitting a beacon including information related to the second period length and information related to the third period, and at least the first time from the beacon transmission timing It is in the first state during the period with the period length of 2, and then transitions to the second state during the third period, either at the end of the third period or at the next beacon transmission timing. Transition to the first state at an earlier timing is that the power consumption of the wireless communication device in the second state is smaller than the power consumption of the wireless communication device in the first state.

  The wireless communication apparatus according to an aspect of the present invention includes means for transmitting a beacon including information related to a first period length, and from the transmission timing of the beacon, at least during the period of the first period length Is in a state, and after the elapse of the period of the first period length, it is possible to transit to the second state until the next beacon transmission timing, the first state is capable of receiving data, and the first state The state 2 is a state in which data reception is restricted, and power consumption in the first state is larger than power consumption in the second state.

  The wireless communication apparatus as one aspect of the present invention includes means for transmitting a beacon including information related to the second period length and information related to the third period, and at least the first time from the beacon transmission timing It is in the first state during the period with the period length of 2, and then transitions to the second state during the third period, either at the end of the third period or at the next beacon transmission timing. Transition to the first state at an earlier timing, the first state is capable of receiving data, the second state is a state where reception of data is restricted, and power consumption in the first state Is larger than the power consumption in the second state.

  A communication control method as one aspect of the present invention is a communication control method for communicating with one or more other wireless terminals by forming a one-to-many connection relationship with one or more other wireless terminals according to the CSMA / CA method. The beacon including information related to the first period length is transmitted from the wireless communication apparatus, and from the transmission timing of the beacon, the wireless communication apparatus is in the first state for at least the period of the first period length, After the elapse of the first period length, until the next beacon transmission timing, it is possible to transition the wireless communication device to the second state, the power consumption of the wireless communication device in the second state is It is smaller than the power consumption of the wireless communication device in the first state, and other wireless terminals do not transmit data while in the second state.

  A communication control method as one aspect of the present invention is a communication control method for communicating with one or more other wireless terminals by forming a one-to-many connection relationship with one or more other wireless terminals according to the CSMA / CA method. The beacon including information related to the second period length and information related to the third period is transmitted from the wireless communication device, and from the transmission timing of the beacon, at least during the period of the second period length The wireless communication device is in a first state, and then the wireless communication device is transitioned to a second state during the third period, at the end of the third period or at the next beacon transmission timing. The wireless communication device is shifted to the first state at the earlier timing, and the power consumption of the wireless communication device in the second state is smaller than the power consumption of the wireless communication device in the first state. It is characterized by.

  A communication control method according to an aspect of the present invention is a communication control method for forming a one-to-many connection relationship and communicating with one or more other wireless terminals in accordance with the CSMA / CA method, wherein the first period Transmitting a beacon including information related to the length, from the transmission timing of the beacon, in the first state at least during the period of the first period length, and after the elapse of the period of the first period length, It is possible to transition to the second state until the beacon transmission timing, the first state is capable of receiving data, the second state is a state where reception of data is restricted, and the first state The power consumption in the state is larger than the power consumption in the second state, and other wireless terminals do not transmit data while in the second state.

  A communication control method according to an aspect of the present invention is a communication control method for communicating by forming a one-to-many connection relationship with one or more other wireless terminals according to the CSMA / CA method. Transmits a beacon including information related to the period length and information related to the third period, from the transmission timing of the beacon, is in the first state at least during the period of the second period length, and then Transition to the second state during the third period, transition to the first state at the earlier of the end time of the third period or the next beacon transmission timing, and the first state Is capable of receiving data, the second state is a state in which data reception is restricted, and power consumption in the first state is larger than power consumption in the second state.

  A communication program as one aspect of the present invention is a communication for causing a computer to execute a wireless communication apparatus that forms a one-to-many connection relationship with one or more other wireless terminals in accordance with the CSMA / CA method. A step of transmitting a beacon including information related to a first period length from the wireless communication apparatus; and a transmission timing of the beacon, the wireless communication apparatus is changed to at least a period of the first period length. And allowing the transition to the second state until the next beacon transmission timing after the elapse of the period of the first period length, and in the second state, The power consumption of the wireless communication device is smaller than the power consumption of the wireless communication device in the first state, and other wireless terminals transmit data while in the second state. And said that there is no I.

  A communication program as one aspect of the present invention is a communication for causing a computer to execute a wireless communication apparatus that forms a one-to-many connection relationship with one or more other wireless terminals in accordance with the CSMA / CA method. A step of transmitting a beacon including information related to the second period length and information related to the third period from the wireless communication device; and at least the second period from the transmission timing of the beacon. The wireless communication device is set to the first state during the long period, and then transitioned to the second state during the third period, at the end of the third period or the next beacon transmission timing. Transitioning to the first state at the earlier timing, and the power consumption of the wireless communication device in the second state is the power consumption in the first state. And wherein the less than the power consumption of the communication device.

  A communication program as one aspect of the present invention is a communication for causing a computer to execute a wireless communication apparatus that forms a one-to-many connection relationship with one or more other wireless terminals in accordance with the CSMA / CA method. A step of transmitting a beacon including information related to a first period length from the wireless communication apparatus; and a transmission timing of the beacon, the wireless communication apparatus is changed to at least a period of the first period length. The first state, and after the elapse of the period of the first period, allowing the transition to the second state until the next beacon transmission timing, wherein the first state is data The second state is a state in which data reception is restricted, and the power consumption in the first state is greater than the power consumption in the second state. While in the state of 2, other wireless terminals do not perform data transmission.

  A communication program as one aspect of the present invention is a communication for causing a computer to execute a wireless communication apparatus that forms a one-to-many connection relationship with one or more other wireless terminals in accordance with the CSMA / CA method. A step of transmitting a beacon including information related to the second period length and information related to the third period from the wireless communication device, and at least the second period from the transmission timing of the beacon. The wireless communication device is set to the first state during the long period, and then transitioned to the second state during the third period, at the end of the third period or the next beacon transmission timing. Transitioning to the first state at the earlier timing, wherein the first state is capable of receiving data, and the second state is a state that restricts reception of data. The power consumption in the first state is larger than the power consumption in the second state.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a configuration example of a communication system according to an embodiment of the present invention.

  In FIG. 1, 1 is the Internet, Z is a 3G base station (second radio device) installed by a mobile phone operator that is connected to the Internet 1, and 2 is a radio link (second radio) provided by the 3G base station Z. (Link), 3 indicates a wireless link (first wireless link) of the IEEE802.11 standard.

  A indicates a communication device (base station) that serves as both a mobile phone terminal and an IEEE802.11 radio base station. Base station A operates as a mobile phone terminal for radio link 2 and IEEE802 for radio link 3. .11 Operates as a radio base station.

  H1 and H2 are wireless terminals (first wireless devices) connected to the base station A via wireless links (first wireless links) 3, respectively. It is assumed that the wireless terminal H1 has the IEEE 802.11 standard power save mode enabled and the wireless terminal H2 has the power save mode disabled.

  Base station (communication device) A and base station Z form a wireless network (second wireless network) according to the 3G standard and perform wireless communication with each other. The base station A and the wireless terminals H1 and H2 form a wireless network (first wireless network) according to the IEEE802.11 wireless LAN standard and perform wireless communication with each other. The wireless terminals H1 and H2 can access the Internet 1 via the base station A.

  Although FIG. 1 shows an example in which two wireless terminals are connected to the wireless link 3, two or more wireless terminals may be connected to the wireless link 3.

  FIG. 2 shows a configuration example of the base station (communication device) A according to the present embodiment.

  Base station A includes 3G wireless communication unit 9, IEEE 802.11 wireless communication unit 10, base station information acquisition unit 12, storage unit 11, transmission permission period determination unit 13, control signal generation unit 14, power management unit 15, and bridge unit (Relay unit) 16 is provided.

  The 3G wireless communication unit (second wireless communication unit) 9 performs wireless communication with the base station Z via the wireless link 2. The 3G wireless communication unit 9 passes the data received to the wireless terminals H1 and H2 via the wireless link 2 to the IEEE802.11 wireless communication unit 10 via the bridge unit 16.

  The IEEE802.11 wireless communication unit (first wireless communication unit) 10 performs wireless communication with the wireless terminals H1 and H2 via the wireless link 3. The IEEE 802.11 wireless communication unit 10 stores the data passed from the 3G wireless communication unit 9 via the bridge unit 16 in an internal buffer, and transmits the data in the buffer to the wireless terminals H1 and H2 according to a necessary procedure. . In addition, when the IEEE802.11 wireless communication unit 10 receives data addressed to devices on the Internet from the wireless terminals H1 and H2, it passes this to the 3G wireless communication unit 9 via the bridge unit 16. The 3G wireless communication unit 9 transmits the passed data via the wireless link 2. The IEEE 802.11 wireless communication unit 10 transmits a beacon signal (control signal) generated by the control signal generation unit 14 at regular intervals to the wireless terminals H1 and H2.

  The bridge unit 16 bridges the 3G wireless communication unit 9 and the IEEE802.11 wireless communication unit 10 so that the IEEE802.11 standard LAN network (first wireless network) and the 3G standard wireless network (second To relay communications between other wireless networks.

  The base station information acquisition unit 12 acquires base station information (see FIG. 4 to be described later) that is information regarding the state of the radio links 2 and 3. Base station information relating to the radio link 3 is particularly referred to as first link information, and information relating to the state of the radio link 2 is particularly referred to as second link information. The base station information acquisition unit 12 includes a first information acquisition unit that acquires first link information and a second information acquisition unit that acquires second link information.

  The storage unit 11 stores therein the base station information (first and second link information) acquired by the base station information acquisition unit 12.

  The transmission permission period determining unit 13 sets a transmission permission period in which data transmission by the wireless terminals H1 and H2 is permitted according to the base station information in the storage unit 11. The transmission permission period is set, for example, in each beacon interval period from the transmission of the previous beacon signal to the transmission of the next beacon signal. For example, the starting point of the transmission permission period is the start time of the beacon interval period. The length of the period may be calculated for each beacon interval period or may be calculated for a plurality of beacon interval periods.

  The control signal generation unit (beacon transmission unit, notification unit) 14 generates a beacon signal at a constant cycle, and includes the control signal specifying the transmission permission period in the generated beacon signal via the IEEE802.11 wireless communication unit 10. To send. As a result, the wireless terminal that has received the beacon signal transmits data only during the transmission permission period specified by the beacon signal within the beacon interval period, and stops data transmission during other periods (transmission prohibited period). Yes (data reception is not prohibited).

  The power management unit 15 supplies power to the IEEE 802.11 wireless communication unit 10 between the transmission permission period and the beacon transmission timing period, and a period other than the transmission permission period and the beacon transmission timing in the communication period. During the (pause period), control is performed so that power supply to the IEEE802.11 wireless communication unit 10 is stopped.

  Each element 9, 10, 11, 12, 13, 14, 15, 16 in FIG. 2 may be configured as hardware or may be configured as a software module executed on the base station A.

  FIG. 3 is a flowchart illustrating an example of a processing procedure of the base station information acquisition unit 12.

  First, the base station information acquisition unit 12 acquires base station information (second link information) related to the state of the radio link 2 from the 3G radio communication unit 9 (S11). This base station information includes the operational status of the interface (for example, the interface up / down information set by the OS) indicating whether the connection with the wireless link 2 is established or disconnected, and the wireless link 2 And statistical information related to communication quality. Examples of the statistical information include RSSI (Received Signal Strength Indicator), BER (Bit Error Rate), and FER (Frame Error Rate).

  Next, the base station information acquisition unit 12 acquires base station information (first link information) related to the state of the radio link 3 from the IEEE 802.11 radio communication unit 10 (S12). The base station information includes statistical information related to the usage status of the radio link 10. This statistical information includes, for example, the number of wireless terminals connected and the traffic volume per unit time. The amount of traffic is represented by the amount of data or the number of packets communicated over the wireless link 3 per unit time, for example, in units of bps (bit per seconds) or pps (packet per seconds). Note that the number of wireless terminals connected and the amount of wireless traffic per unit time are specific statistical information that only the base station can know in the infrastructure mode.

  Finally, the base station information acquisition unit 12 registers the acquired base station information in the storage unit 11 (S13). An example of base station information is shown in FIG.

  FIG. 5 is a flowchart illustrating an example of a processing procedure of the transmission permission period determination unit 13, the control signal generation unit 14, and the power management unit 15.

  First, the transmission permission period determination unit 13 acquires base station information from the storage unit 11 (S21), calculates a transmission permission period length from the acquired base station information, and transmits a transmission permission period length in the beacon interval period. The period is determined (S22). Here, a period that continues for the transmission permission period length from the start time of the beacon interval period is determined as the transmission permission period. Then, the control signal generation unit 14 instructs to prohibit data transmission in a control signal that specifies the determined transmission permission period (that is, in the beacon interval period, data transmission is permitted in the transmission permission period, and in other transmission prohibition periods. Beacon signal including the control signal) is generated and transmitted (S23).

  Here, it is assumed that the base station A internally manages the reference value of the transmission permission period length, and is 100 msec in the present embodiment, for example. The reference value may be changed by an administrator accessing the GUI of the base station A using a web browser or the like. Hereinafter, a calculation example of the transmission permission period length according to the base station information will be shown.

<Example of calculation of transmission permission period length>
(1) Example of calculating the transmission permission period length based on the interface operating status
When the interface operating state of the 3G wireless communication unit 9 is DOWN, the data transmitted by the wireless terminals H1 and H2 connected to the wireless link 3 is discarded inside the base station A. That is, when the interface operating state is DOWN, it is desirable to suppress the opportunity for the wireless terminals H1 and H2 to transmit data as much as possible. Therefore, for example, a rule for setting the transmission permission period length to the minimum value is set. Here, it is assumed that the minimum value is internally managed by the base station A, and is 10 msec in this embodiment, for example. The minimum value may be changed by an administrator accessing the GUI of the base station A using a web browser or the like. In the example in which the interface operating state in FIG. 4 is DOWN, the transmission permission period length is a minimum value of 10 msec.

(2) Calculation example of transmission permission period length based on RSSI When the RSSI of the wireless link 2 for Internet access is significantly reduced, a large amount of communication data is lost in the wireless link 2 and communication is impossible. That is, it is desirable to minimize the opportunity for the wireless terminals H1 and H2 to transmit data when RSSI is significantly reduced. Therefore, for example, a rule is set such that when the RSSI falls below a certain threshold, the transmission permission period length is set to the minimum value. Here, it is assumed that the threshold value and the minimum value are managed internally by the base station A. In this embodiment, for example, the threshold value is -70 dBm and the minimum value is 10 msec. The threshold value and the minimum value may be changed by an administrator accessing the GUI of the base station using a web browser or the like. In the example in which the RSSI in FIG. 4 is −80 dBm, the transmission permission period length is the minimum value of 10 msec because it is below the threshold of −70 dBm.

(3) Calculation example of transmission permission period length based on BER When the BER of the wireless link 2 for Internet access increases remarkably, a large amount of communication data is lost in the wireless link 2 and communication is impossible. That is, when the BER significantly increases, it is desirable to minimize the opportunity for the radio terminals H1 and H2 to transmit data. Therefore, for example, a rule is set such that when the BER exceeds a certain threshold, the transmission permission period length is set to the minimum value. Here, the threshold value and the minimum value are assumed to be managed internally by the base station A. In this embodiment, for example, the threshold value is 10% and the minimum value is 10 msec. Further, the threshold value and the minimum value may be changed by an administrator accessing the GUI of the base station A using a web browser or the like. In the example in which the BER in FIG. 4 is 50%, it exceeds the threshold of 10%, so the transmission permission period length is the minimum value of 10 msec.

(4) Calculation example of transmission permission period length based on FER When the FER of the wireless link 2 for Internet access increases remarkably, a lot of communication data is lost in the wireless link 2 and communication is impossible. That is, when the FER significantly increases, it is desirable to minimize the opportunity for the radio terminals H1 and H2 to transmit data. Therefore, for example, a rule is set to set the transmission permission period length to the minimum value when FER exceeds a certain threshold. Here, the threshold value and the minimum value are assumed to be managed internally by the base station A. In this embodiment, for example, the threshold value is 10% and the minimum value is 10 msec. The threshold value and the minimum value may be changed by an administrator accessing the GUI of the base station using a web browser or the like. In the example in which the FER in FIG. 5 is 50%, it exceeds the threshold of 10%, so the transmission permission period length is the minimum value of 10 msec.

(5) Example of calculation of transmission permission period length based on the number of wireless terminal connections As the number of wireless terminal connections increases, the traffic volume of the wireless link 3 may increase. If the transmission permission period length is not increased as the traffic amount increases, data may be discarded inside the base station A and the wireless terminals H1 and H2. Therefore, for example, a rule for extending the transmission permission period length by 20 msec per wireless terminal is set. In the example in which the number of connected wireless terminals in FIG. 5 is 5, the transmission permission period length is calculated as “reference value 100 msec + 5 wireless terminals × 20 msec” and becomes 200 msec.

(6) Example of transmission permission period length calculation based on traffic volume If the transmission permission period length does not increase as the traffic volume increases, data can be discarded inside base station A and wireless terminals H1 and H2. There is sex. Therefore, for example, a rule is set to extend the transmission permission period length by 20 msec for a traffic amount of 200 pps. In the example in which the traffic volume in FIG. 4 is 1000 pps, the transmission permission period length is calculated as “reference value 100 msec + traffic volume 1000 pps ÷ 200 pps × 20 msec” and becomes 200 msec.

  Here, an example is shown in which the transmission permission period length is calculated from one of various types of base station information, but a plurality of base station information may be calculated in combination as follows.

  For example, when combining the calculation examples (1), (2), (3), and (4) that set the transmission permission period length to the minimum value, the interface operating status is DOWN, RSSI is below the threshold, FER If any one of the above conditions is satisfied, the method of setting the minimum value can be adopted.

  Extending the transmission permission period length When combining the calculation examples of (5) and (6), for example, the transmission permission period length is extended by 20 msec per wireless terminal, and the transmission permission period length is 20 msec per 200 pps traffic volume. It is possible to adopt a method of adding the extension periods such as extending. For example, in the example where the number of wireless terminal connections in Fig. 4 is 5 and the traffic volume is 1000 pps, the transmission permission period length is calculated as "reference value 100 msec + 5 wireless terminals x 20 msec + traffic volume 1000 pps / 200 pps x 20 msec" 300 msec.

  Set the transmission permission period length to the minimum value (1), (2), (3), at least one of (4) and increase the transmission permission period length (5), at least (6) When combining one or more, give priority to the former calculation result. Therefore, if any one of the above minimum value conditions corresponding to (1), (2), (3), and (4) is satisfied, the transmission permission period length is set to the minimum value. The calculation of (5) or (6) is not performed and the transmission permission period is not extended regardless of the values of the number of wireless terminals connected and the traffic volume.

  The power management unit 15 supplies power to the wireless communication unit 16 during the transmission timing period of the beacon signal and the transmission permission period determined above, and a pause period other than the transmission permission period and the beacon transmission timing period in the communication period. During the period, control is performed so as to stop power supply to the wireless communication unit 16 (S24).

  Thereafter, the base station A periodically repeats S21 to S24.

  Hereinafter, the specific processing flow of steps S23 and S24 will be described in more detail with reference to FIG.

  FIG. 6 shows an example of the flow of processing for transmitting and receiving control signals and data at base station A, wireless terminal H1, and wireless terminal H2 in FIG.

  In this example, a beacon signal including a Quiet IE (Quiet Information Element) field defined by IEEE802.11 is used as a beacon signal. This field includes a field (Quiet Offset field) for specifying an offset time for starting prohibition of data transmission and a field (Quiet Duration field) for specifying a prohibition time until the prohibition of data transmission is canceled. When using this beacon signal, the control signal is the data signal of the Quiet Duration field and Quiet Offset field of Quiet IE, and the transmission permission period determination unit 13 calculates the offset permission period and the transmission permission period by calculating the prohibition time. Set up. Here, it is assumed that the transmission cycle of the beacon signal is set to 500 msec, the offset time is 100 msec, and the prohibition time is calculated as 400 msec obtained by subtracting the offset time from the transmission cycle of the beacon signal. In addition, it is assumed that the power saving mode is valid for the wireless terminal H1, and the power saving mode is invalid for the wireless terminal H2.

  First, the base station A transmits a beacon signal including TIM for notifying that there is data addressed to the wireless terminal H1 (for example, data received from the Internet 2) and Quiet IE (S101). The format of the beacon signal is shown in FIG. Set Quiet IE's Quiet Duration field to 400msec and Quiet Offset field to 100msec. As a result, the wireless terminal H1 and the wireless terminal H2 that have received the beacon signal are allowed to transmit data during a period of 100 msec (offset time) from the reception (transmission permission period), and further after 100 msec has elapsed. Data transmission can be stopped during the transmission prohibition period until 400 msec (prohibition time) elapses. In the beacon signal transmitted in S101, data transmission is not prohibited after 400 msec.

  The base station A can calculate parameters such as Quiet Duration and Quiet Offset (that is, calculate prohibition time and offset time) every time a beacon signal is transmitted. Here, the prohibition time set in Quiet Duration can be set larger than the transmission period of the beacon signal, and in this case, even if the wireless terminal cannot receive the next beacon signal due to radio wave interference etc. It can be directed to suppress the data transmission of the wireless terminal until the transmission of the beacon signal.

  Here, the beacon signal is a control signal for the purpose of periodically advertising the existence and availability of the radio link to the radio terminal by the base station, and the radio terminal that has shifted to the power save mode transmits the beacon signal. In synchronization with the period, the sleep state is canceled and the beacon signal reception process is reliably performed. Therefore, it can be said that the method of notifying the transmission permission period by the beacon signal is the most suitable part for reliably reporting information to the wireless terminal as compared with the notification method shown in Patent Document 1.

  The wireless terminals H1 and H2 that have received the beacon signal are permitted to transmit data until 100 msec (offset time) has elapsed. Since the wireless terminal H1 has received the notification that the data addressed to itself is buffered from the base station A in S101, the wireless terminal H1 transmits a PS-Poll defined in the IEEE802.11 standard in order to poll the base station A. Then, the data addressed to itself is received from the base station A, and the data is transmitted to the base station A as necessary (S102 to S104). The wireless terminal H1 in which the power save mode is valid transitions to the sleep state after data transmission / reception (S105). The wireless terminal H2 in which the power save mode is invalid performs data transmission / reception during the offset time (during the transmission permission period) (S106, S107).

  Note that the order of the data transmission / reception processing shown in FIG. 6 is an example, and data is actually transmitted / received according to the order determined by the CSMA / CA mechanism.

  When 100 msec (offset time) has elapsed from the transmission of the beacon signal, the base station A transitions to the sleep state (S108), and the wireless terminal H2 stops transmitting data (S109). Furthermore, when the transmission timing period for transmitting the next beacon signal is reached, the base station A cancels the sleep state (S110, S111) and transmits the beacon signal (S112). On the other hand, the wireless terminal H1 cancels the sleep state 111 in order to receive the next beacon signal (S112) immediately after 100 msec (offset time) has elapsed since the reception of the beacon signal and further 400 msec has elapsed (S112) ( S111). In the next beacon signal, the same control signal as the previous time is set, and the wireless terminal H2 that has received the next beacon signal resumes data transmission / reception during the offset time (S113).

  In this embodiment, the transmission permission period length from the start time of the beacon interval period is determined as the transmission permission period. However, the transmission permission period may be divided and set within the beacon interval period. For example, when the transmission permission period length is 200 msec, the offset time is 100 msec and the prohibition time is 300 msec in the example of FIG. 6, the offset time is 100 msec, and the transmission of the next beacon signal after the prohibition time elapses. A transmission permission period may be a period of 100 msec.

  From the above, it becomes possible for the base station A to transition to the sleep state during the period of the beacon signal transmitted at a constant period and suppress power consumption. In addition, the wireless terminal H1 in which the power save mode is effective immediately transitions to the sleep state after transmission / reception of desired data to suppress power consumption, and the wireless terminal H2 in which the power save mode is not effective has a prohibited time after the offset time. Power consumption can be reduced by stopping the inter-data transmission. As a result, the power consumption of the base station A and the wireless terminals H1 and H2 can be suppressed simultaneously.

(Second embodiment)
In the first embodiment, the data transmission of the wireless terminal is controlled using the Quiet IE's Quiet Duration field and Quiet Offset field, but in this embodiment, the CF-Poll control signal and CF defined in the IEEE 802.11 standard are used. A case where data transmission is controlled using the -ACK + CF-End control signal will be described. The block diagram and operation flowchart of the base station in this embodiment are the same as those in the first embodiment. In the present embodiment, the operation of the control signal generation unit 14 is particularly different from that of the first embodiment, and the difference from the first embodiment will be described below.

  In the present embodiment, the control signal generation unit (data transmission control unit) 14 individually transmits a transmission permission frame (control signal) for allowing data transmission to the wireless terminals H1 and H2 and a data transmission individually during the transmission permission period. Transmission prohibition frames (control signals) to be prohibited are transmitted via the IEEE802.11 wireless communication unit 10 in this order. Thereby, the control signal generation unit 14 performs control so that data transmission is performed only between the time when the wireless terminals H1 and H2 receive the transmission permission frame and the time when the transmission prohibition frame is received. After receiving the transmission prohibition frame, the wireless terminals H1 and H2 cannot transmit data until the transmission permission frame is received again.

  FIG. 8 shows an example of a specific processing flow of S23 and S24 when a CF-Poll control signal (transmission permission frame) and a CF-ACK + CF-End control signal (transmission prohibition frame) are used as control signals. Indicates. The CF-Poll control signal is a signal for instructing the start of data transmission, and corresponds to, for example, the transmission permission frame. The CF-ACK + CF-End control signal is a signal indicating an affirmation confirmation of data reception and at the same time instructing to stop data transmission, and corresponds to, for example, the transmission-inhibited frame. The transmission permission period is assumed to be 100 msec continuous from the start time of the beacon interval period, and the transmission period of the beacon signal is set to 500 msec. In addition, it is assumed that the power saving mode is valid for the wireless terminal H1, and the power saving mode is invalid for the wireless terminal H2.

  First, the base station A transmits a beacon signal including a TIM notifying that there is data addressed to the wireless terminal H1 (S201).

  Next, the base station A performs data transmission / reception with the wireless terminal H1 and the wireless terminal H2 until 100 msec has elapsed since the transmission of the beacon signal. More specifically, the wireless terminal H1 in which the power save mode is valid receives a notification from the base station A that there is data buffered by the TIM, and transmits a PS-Poll signal to the base station A to transmit data. Is received (S202, S203). In addition, the wireless terminal H1 transmits data when receiving the CF-Poll control signal (transmission permission frame) from the base station A (S204, S205, S206). That is, permission for data transmission is given by base station A by polling with a CF-Poll control signal. After receiving data from the wireless terminal H1, the base station A transmits a CF-ACK + CF-End control signal to the wireless terminal H1, thereby notifying the wireless terminal H1 of the positive confirmation of data reception and at the same time the wireless terminal H1. Is instructed to stop (prohibit) data transmission (S207). Receiving the CF-ACK + CF-End control signal, the wireless terminal H1 stops data transmission (S208). The wireless terminal H1 in which the power save mode is valid transitions to the sleep state after stopping data transmission (S209).

  The wireless terminal H2 in which the power save mode is invalid receives data from the base station A (S210), and transmits data when receiving the CF-Poll control signal from the base station A (S211 and S212). , S213). The base station A transmits a CF-ACK + CF-End control signal to the wireless terminal H2, thereby notifying the wireless terminal H2 of a positive confirmation of data reception and simultaneously instructing the wireless terminal H2 to stop data transmission. Receiving the CF-ACK + CF-End control signal, the wireless terminal H2 stops data transmission (S215).

  Note that the order of the data transmission / reception processing shown in FIG. 8 is an example, and data is actually transmitted / received according to the order determined by the CSMA / CA mechanism.

  When 100 msec (offset time) has elapsed since the transmission of the beacon signal, the base station A transitions to the sleep state (S216), cancels the sleep state during the next beacon signal transmission timing period (S217), and transmits the beacon signal. (S219). On the other hand, the wireless terminal H1 in the sleep state cancels the sleep state 111 in order to receive the next beacon signal (S218).

  As described above, the base station A can transition to the sleep state and suppress power consumption. In addition, the wireless terminal H1 in which the power save mode is effective transitions to the sleep state immediately after transmission / reception of desired data to suppress power consumption, and the wireless terminal H2 in which the power save mode is not effective transmits data after the offset time. Stopping power consumption can be reduced. As a result, the power consumption of the base station A and the wireless terminals H1 and H2 can be suppressed simultaneously.

  As described above, according to the embodiment of the present invention, it is possible to provide means for simultaneously realizing power saving of the base station and the wireless terminal in the infrastructure mode of the wireless system.

The figure which shows the structural example of the communication system concerning one Embodiment of this invention. FIG. 2 is a block diagram showing a configuration example of a base station A. The flowchart which shows the flow of a process of operation | movement of a base station information acquisition part. The figure which shows an example of base station information. The flowchart which shows the flow of operation | movement of a transmission permission period determination part, a control signal production | generation part, and a power management part. The figure which shows an example of the flow of a process which transmits / receives a control signal and data between the base station A, the radio | wireless terminal H1, and the radio | wireless terminal H2. The figure which shows the format of a beacon signal. The figure which shows the other example of the flow of a process which transmits / receives a control signal and data between the base station A, the radio | wireless terminal H1, and the radio | wireless terminal H2.

1: Internet
2: 3G wireless link (second wireless link)
3: IEEE802.11 wireless link (first wireless link)
A: Base station (communication equipment)
Z: 3G base station (second wireless device)
H1, H2: Wireless terminal (first wireless device)
9: 3G wireless communication unit (second wireless communication unit)
10: IEEE802.11 wireless communication unit (first wireless communication unit)
11: Memory unit
12: Base station information acquisition unit (first and second information acquisition units)
13: Transmission permission period determining unit (period determining unit)
14: Control signal generation unit (beacon transmission unit, notification unit, data transmission control unit)
15: Power Management Department

Claims (29)

Means for transmitting a beacon including information related to the first period length, and is in a first state at least during the period of the first period length from the transmission timing of the beacon. It is possible to transit to the second state until the beacon transmission timing, and the power consumption of the wireless communication device in the second state is smaller than the power consumption of the wireless communication device in the first state, ,
A second wireless communication device that communicates with a wireless network different from the wireless communication device;
An acquisition unit for acquiring a state of a wireless link of the second wireless communication device;
A determination unit configured to determine the first period length based on a state of a wireless link of the second wireless communication device; The terminal according to claim 1, further comprising setting means for setting information related to determination of the first period length. An acquisition unit for acquiring a state of a wireless link of the wireless communication device;
The terminal according to claim 1, wherein the determination unit determines the first period length based on a state of a wireless link of the wireless communication device and a state of a wireless link of the second wireless communication device.   The terminal according to claim 1, further comprising display means and input means. Means for transmitting a beacon including information relating to the second period length and information relating to the third period;
From the transmission timing of the beacon, the state is in the first state for at least the period of the second period length, and then transitions to the second state for the third period, and the end of the third period Transition to the first state at the earlier of the time point or the next beacon transmission timing, and the power consumption of the wireless communication device in the second state is smaller than the power consumption of the wireless communication device in the first state It is characterized by
Wireless communication device. Comprising means for transmitting a beacon including information relating to the first period length;
From the transmission timing of the beacon, it is in the first state for at least the period of the first period length, and after the elapse of the period, it is possible to transition to the second state until the next beacon transmission timing,
The first state is a state where data can be received, the second state is a state where data reception is restricted, and the power consumption in the second state is smaller than the power consumption in the first state. A wireless communication device. A wireless communication device according to claim 6;
A setting means for setting information relating to the determination of the first period length. A wireless communication device according to claim 6;
A first acquisition unit for acquiring a state of a wireless link of the wireless communication device;
A determination unit configured to determine the first period length based on a state of the radio link; A wireless communication device according to claim 6;
A first acquisition unit for acquiring a state of a wireless link of the wireless communication device;
A second wireless communication device that communicates with a wireless network different from the wireless communication device; a second acquisition unit that acquires a state of a wireless link of the second wireless communication device;
A terminal comprising: a determination unit configured to determine the first period length based on a wireless link state of the wireless communication device and a wireless link state of the second wireless communication device. A wireless communication device according to claim 7;
A second wireless communication device that communicates with a wireless network different from the wireless communication device;
A second acquisition unit for acquiring a state of a wireless link of the second wireless communication device;
A determination unit configured to determine the first period length based on a state of a wireless link of the second wireless communication device;
With a terminal. The terminal according to claim 6, further comprising display means and input means. Means for transmitting a beacon including information relating to the second period length and information relating to the third period;
From the transmission timing of the beacon, the state is in the first state for at least the period of the second period length, and then transitions to the second state for the third period, and the end of the third period Transition to the first state at the earlier of the time point or the next beacon transmission timing, the first state is capable of receiving data, and the second state is a state of restricting data reception. The wireless communication device characterized in that power consumption in the second state is smaller than power consumption in the first state. A wireless communication device according to claim 12,
A setting means for setting information relating to the determination of the second period length. A wireless communication device according to claim 12,
A first acquisition unit for acquiring a state of a wireless link of the wireless communication device;
A determination unit configured to determine the second period length based on a state of the radio link; A wireless communication device according to claim 12,
A first acquisition unit for acquiring a state of a wireless link of the wireless communication device;
A second wireless communication device that communicates with a wireless network different from the wireless communication device; a second acquisition unit that acquires a state of a wireless link of the second wireless communication device;
A terminal comprising: a wireless link state of the wireless communication device; and a determination unit that determines the second period length based on the wireless link state of the second wireless communication device. A wireless communication device according to claim 12,
A second wireless communication device that communicates with a wireless network different from the wireless communication device;
A second acquisition unit for acquiring a state of a wireless link of the second wireless communication device;
A determination unit configured to determine the second period length based on a state of a wireless link of the second wireless communication device;
With a terminal. The terminal according to claim 13, further comprising display means and input means. A beacon including information related to the first period length is transmitted from the wireless communication apparatus, and the wireless communication apparatus is in the first state for at least the period of the first period length from the transmission timing of the beacon. After the elapse of time, the wireless communication device can be shifted to the second state until the next beacon transmission timing, and the power consumption of the wireless communication device in the second state is the wireless communication device in the first state. Less than the power consumption of
Obtaining a state of a wireless link of a second wireless communication device communicating with a wireless network different from the wireless communication device;
A communication control method for determining the first period length based on a state of a radio link of the second radio communication device. A beacon including information related to the first period length is transmitted from the wireless communication device,
From the beacon transmission timing, the wireless communication device is in the first state for at least the period of the first period length, and after the elapse of the period, the wireless communication device is kept in the second state until the next beacon transmission timing. It is possible to transition to the state of
The first state is a state where the wireless communication apparatus can receive data, the second state is a state where reception of data of the wireless communication apparatus is restricted, and the power consumption in the second state is the first state. It is smaller than the power consumption in the state 1,
Communication control method. A communication control method for communicating with one or more other wireless terminals by forming a one-to-many connection relationship with one or more other wireless terminals according to the CSMA / CA method,
Transmitting a beacon including information related to the first period length from the wireless communication device;
From the beacon transmission timing, the wireless communication device is in the first state for at least the period of the first period length, and after the elapse of the period, the wireless communication device is kept in the second state until the next beacon transmission timing. It is possible to transition to the state of
The power consumption of the wireless communication device in the second state is smaller than the power consumption of the wireless communication device in the first state, and other wireless terminals perform data transmission while in the second state. There is no communication control method. A communication control method for communicating with one or more other wireless terminals by forming a one-to-many connection relationship with one or more other wireless terminals according to the CSMA / CA method,
A beacon including information related to the second period length and information related to the third period is transmitted from the wireless communication device,
From the transmission timing of the beacon, the wireless communication device is in the first state for at least the period of the second period length, and then the wireless communication device is in the second state for the third period. Transition, transition the wireless communication device to the first state at the earlier of the end of the third period or the next beacon transmission timing,
A communication control method, wherein power consumption of the wireless communication device in the second state is smaller than power consumption of the wireless communication device in the first state. A communication control method for communicating by forming a one-to-many connection relationship with one or more other wireless terminals according to the CSMA / CA method,
Send a beacon containing information about the first period length,
From the transmission timing of the beacon, it is in the first state for at least the period of the first period length, and after the elapse of the period, it is possible to transition to the second state until the next beacon transmission timing,
The first state is capable of receiving data, the second state is a state of restricting data reception, and the power consumption in the second state is smaller than the power consumption in the first state, While in the second state, another wireless terminal does not perform data transmission. A communication control method for communicating by forming a one-to-many connection relationship with one or more other wireless terminals according to the CSMA / CA method,
Transmitting a beacon including information relating to the second period length and information relating to the third period,
From the transmission timing of the beacon, the state is in the first state for at least the period of the second period length, and then transitions to the second state for the third period, and the end of the third period Transition to the first state at the earlier of the time point or the next beacon transmission timing,
The first state is a state where data can be received, the second state is a state where data reception is restricted, and the power consumption in the second state is smaller than the power consumption in the first state. A communication control method characterized by the above. A communication program for causing a computer to execute a wireless communication device,
Transmitting a beacon including information related to the first period length from the wireless communication device;
From the beacon transmission timing, the wireless communication device is in the first state for at least the period of the first period length, and after the elapse of the period, the wireless communication device is kept in the second state until the next beacon transmission timing. Making it possible to transition to the state of
Based on the state of the radio link of the second radio communication device communicating with a radio network different from the radio communication device, and the status of the radio link of the second radio communication device, the first period length is calculated. A step of determining,
The communication program characterized in that the power consumption of the wireless communication device in the second state is smaller than the power consumption of the wireless communication device in the first state. A communication program for causing a computer to execute a wireless communication device,
Transmitting a beacon including information related to the first period length from the wireless communication device;
From the beacon transmission timing, the wireless communication device is in the first state for at least the period of the first period length, and after the elapse of the period, the wireless communication device is kept in the second state until the next beacon transmission timing. Making it possible to transition to the state of
The first state is a state where the wireless communication apparatus can receive data, the second state is a state where reception of data of the wireless communication apparatus is restricted, and the power consumption in the second state is the first state. A communication program characterized by being smaller than the power consumption in the state of 1. A communication program for causing a computer to execute a wireless communication apparatus that communicates by forming a one-to-many connection relationship with one or more other wireless terminals according to the CSMA / CA method,
Transmitting a beacon including information related to the first period length from the wireless communication device;
From the beacon transmission timing, the wireless communication device is set to the first state for at least the period of the first period length, and transitions to the second state after the period elapses until the next beacon transmission timing. Comprising the steps of enabling
The power consumption of the wireless communication device in the second state is smaller than the power consumption of the wireless communication device in the first state, and other wireless terminals perform data transmission while in the second state. A communication program characterized by not. A communication program for causing a computer to execute a wireless communication apparatus that communicates by forming a one-to-many connection relationship with one or more other wireless terminals according to the CSMA / CA method,
Transmitting a beacon including information related to the second period length and information related to the third period from the wireless communication device;
From the transmission timing of the beacon, the wireless communication device is set to the first state for at least the period of the second period length, and then changed to the second state for the third period. Transitioning to the first state at the earlier of the end of the period or the next beacon transmission timing,
A communication program characterized in that power consumption of the wireless communication device in the second state is smaller than power consumption of the wireless communication device in the first state. A communication program for causing a computer to execute a wireless communication apparatus that communicates by forming a one-to-many connection relationship with one or more other wireless terminals according to the CSMA / CA method,
Transmitting a beacon including information related to the first period length from the wireless communication device;
From the beacon transmission timing, the wireless communication device is set to the first state for at least the period of the first period length, and transitions to the second state after the period elapses until the next beacon transmission timing. Comprising the steps of enabling
The first state is capable of receiving data, the second state is a state of restricting data reception, and the power consumption in the second state is smaller than the power consumption in the first state, Another wireless terminal does not transmit data while in the second state. A communication program for causing a computer to execute a wireless communication apparatus that communicates by forming a one-to-many connection relationship with one or more other wireless terminals according to the CSMA / CA method,
Transmitting a beacon including information related to the second period length and information related to the third period from the wireless communication device;
From the transmission timing of the beacon, the wireless communication device is set to the first state for at least the period of the second period length, and then changed to the second state for the third period. Transitioning to the first state at the earlier of the end of the period or the next beacon transmission timing,
The first state is a state where data can be received, the second state is a state where data reception is restricted, and the power consumption in the second state is smaller than the power consumption in the first state. A communication program characterized by

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