JP2005277647A - Radio device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio device capable of suppressing power consumption and reception leakage and preventing the amount of data communication from increasing. <P>SOLUTION: When a C station receives RTS transmitted from an A station, the C station refers to the transmission destination address of a data packet added to the header of the RTS and confirms that a data packet addressed to the other station is transmitted from the transmission destination address. Then, the C station obtains a packet transmission prohibition period based on communication schedule period information added to the header of the RTS, sets the packet transmission prohibition period to be a power reduction period, and stops or reduces power supply to RF and BBP sections and the like for the power reduction period. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless device used in a wireless communication network in which packet communication is performed, and more particularly to power consumption suppression of the wireless device.

Conventionally, power consumption of a wireless device used in a wireless communication network in which packet communication is performed is reduced.
For example, in communication between an access point and a mobile terminal (wireless device), it is possible to appropriately arrange a wake-up signal in a MAC (Media Access Control) frame to maximize sleep time and save energy of the mobile terminal. Has been done. (For example, see Patent Document 1)
Also, for example, if the access point is scanned and communication with the access point is possible, the scan interval time is set and the normal mode or the power save mode is entered. On the other hand, when communication is not possible, a scan interval time longer than the scan interval time is set and the deep sleep mode is entered. (For example, see Patent Document 2)
For example, when a packet is received from the parent device, the time T1 in the timer is set thereafter, and the power of the receiving unit is turned off. Then, after the time T1 has elapsed, another time T2 is set in the timer, and the power of the receiving unit is turned on to perform reception. Then, after the time T2 has elapsed, the power of the receiving unit is turned off by setting the previous time T1 in the timer again. (For example, see Patent Document 3)
However, in any of the above-described wireless device power consumption suppression methods, each power consumption suppression period (for example, the sleep period or the time 1) in each wireless device is fixed. When data addressed to itself occurs, there is a problem that data addressed to itself cannot be received until the next power recovery period.

Therefore, in order to solve such a problem, for example, when data transmission is performed to a terminal station in a network where a link is established, data indicating the next data transfer time is sent together with the data, and the data is received. It is conceivable that the terminal station that has been turned off turns off the power during the sleep time obtained from the time indicated in the data. (For example, see Patent Document 4)
As a result, each terminal station can turn on the power according to the reception timing of the data addressed to itself and receive the data addressed to itself. Can do.
Special Table No. 2002-541731 (pages 18-35, FIGS. 1-19) JP 2003-108271 (Pages 5-9, FIGS. 1-6) JP 2000-307550 A (pages 4-9, FIGS. 1-15) JP 2002-300195 (7th to 15th pages, FIGS. 1 to 12)

  However, in the method of suppressing power consumption by turning off the power, the data indicating the time for the next data transfer is sent together with the data as described above. There is a problem that the amount of data communication increases because it is necessary to add data to be indicated.

  Accordingly, an object of the present invention is to provide a wireless device capable of preventing an increase in data communication volume while suppressing power consumption and reception omission.

In order to solve the above problems, the present invention adopts the following configuration.
In other words, the wireless device of the present invention is a wireless device used in a wireless communication network in which packet communication is performed, and when the packet transmitted / received between other wireless devices is received, the other added to the packet A power reduction period is obtained based on scheduled communication period information indicating a scheduled use period of a wireless line between wireless devices, and power supply to a part of circuits of the wireless device is stopped or suppressed. And

  In this way, a wireless device that has received a packet transmitted / received between other wireless devices can stop or suppress power supply to some circuits of the wireless device during the power reduction period based on the scheduled communication period information. Therefore, power consumption can be reduced accordingly.

  In addition, for example, when a wireless device that has received a packet transmitted / received between other wireless devices has a power reduction period from the end of reception of a packet to the end of reception of an ACK (Acknowledgement) corresponding to the packet, It is possible to prepare for the reception of the packet that comes immediately next, and it is possible to suppress reception omission.

  Further, the packet transmitted / received between the other wireless devices is configured as a transmission request packet indicating that a data packet is desired to be transmitted, a reception preparation completion packet indicating that reception preparation of the data packet is completed, or the data packet. May be.

The power reduction period may be configured to end before the packet transmission prohibition period.
Thereby, it is possible to prepare for the reception of the next packet with more certainty.

  The wireless device may be configured to stop or suppress power supply to some circuits of the wireless device during the power reduction period when the power reduction period is longer than a predetermined period.

  Thereby, for example, when a data packet is divided and transmitted by fragmentation (fragmentation) and the period of ACK and ACK is shortened, power supply to some circuits of the wireless device is not stopped or suppressed. Therefore, it is possible to reduce power consumed for control of stopping or suppressing power supply to some circuits of the wireless device.

  According to the present invention, it is possible to prevent an increase in data communication volume while suppressing power consumption and reception omission.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an example of power consumption suppression in a wireless device according to an embodiment of the present invention. FIG. 1A shows an example of packet transmission timing and packet reception timing of A station (wireless device) having data (DATA) addressed to B station. FIG. 1B shows an example of packet transmission timing and packet reception timing of station B (wireless device). FIG. 1C shows an example of the packet reception timing of station C (wireless device) when at least station A can be received. FIG. 1D shows the start timing (upward arrow) and end timing (downward arrow) of the packet transmission prohibition period (NAV: Network Allocation Vector) of the C station. FIG. 1E shows power supply stop timing (downward arrow) and power supply restart timing (upward arrow) to the RF (Radio Frequency) unit and BBP (Base Band Processor) unit of the C station. In addition, the wireless device according to the present embodiment may be used for, for example, an IEEE 802.11 wireless LAN wireless communication network.

First, as shown in FIG. 1A, the station A transmits an RTS (Request To Send) (transmission request packet) indicating that data is transmitted to the station B.
Next, when receiving the RTS transmitted from the A station, the B station refers to the transmission destination address of the data added to the RTS header.

  Next, when the B station confirms that the data addressed to itself is transmitted by the transmission destination address, the preparation for reception is completed as shown in FIG. A CTS (Clear To Send) (reception ready packet) is transmitted.

Next, as shown in FIG. 1A, the station A receives the CTS transmitted from the station B and transmits a data packet addressed to the station B.
Then, as shown in FIG. 1B, the B station returns an ACK to the A station when it receives the data packet transmitted from the A station.

In the present embodiment, the power consumption control of the C station when communication is performed between the A station and the B station will be considered.
First, as shown in FIG. 1C, the station C refers to the transmission destination address of the data packet added to the RTS header when it receives the RTS transmitted from the station A.

  Next, when the station C confirms that the data packet addressed to the other station is transmitted by the transmission destination address, the communication schedule period information (the wireless channel between the station A and the station B is also added to the header of the RTS). 1 (d) based on information indicating a scheduled period to be used, for example, information indicating a period from an RTS reception end timing at the B station to an ACK reception end timing at the A station). Such a packet transmission prohibition period is obtained, and packet transmission is prohibited during that period.

  Then, the C station sets the obtained packet transmission prohibition period as a power reduction period, and stops or reduces power supply to the power reduction period RF unit, the BBP unit, and the like. Station C may set the power reduction period to end a little before the packet transmission prohibition period, as shown in FIG.

  As described above, the C station that has received the RTS addressed to the B station transmitted from the A station stops or suppresses the power supply to some circuits such as the power reduction period RF unit and the BBP unit based on the scheduled communication period information. Therefore, power consumption can be reduced accordingly.

  In addition, the C station that has received the RTS addressed to the B station transmitted from the A station has, for example, a power reduction period from the end of RTS reception to the end of ACK reception corresponding to the RTS as described above. Then, it is possible to prepare for the reception of the next RTS or the like, and it is possible to suppress the reception omission.

  In addition, the C station that has received the RTS addressed to the B station transmitted from the A station sets the power reduction period to end slightly before the packet transmission prohibition period, so that the RTS that comes immediately more reliably, etc. Can be prepared.

Next, another example of power consumption suppression in the wireless device according to the embodiment of the present invention will be described.
FIG. 2 is a diagram illustrating another example of power consumption suppression in the wireless device according to the embodiment of the present invention. The example of communication between stations A and C shown in FIG. 2 is basically the same as the example of communication between stations A and C shown in FIG. 1, but it is assumed that station C can receive only station B. Is different from the communication example between the stations A to C shown in FIG.

First, as shown in FIG. 2C, when the C station receives the CTS transmitted from the B station, the C station refers to the transmission destination address of the data packet added to the CTS header.
Next, when the station C confirms that the data packet addressed to the other station is transmitted using the transmission destination address, the scheduled communication period information (for example, the CTS reception end timing at the station A) is also added to the CTS header. 2), a packet transmission prohibition period as shown in FIG. 2D is obtained, and transmission of packets during that period is prohibited.

  Then, the C station sets the obtained packet transmission prohibition period as a power reduction period, and stops or reduces power supply to the power reduction period RF unit, the BBP unit, and the like. Station C may set the power reduction period to end a little before the packet transmission prohibition period, as shown in FIG.

  Thus, the C station that has received the CTS addressed to the A station transmitted from the B station stops or suppresses the power supply to some circuits such as the power reduction period RF unit and the BBP unit based on the scheduled communication period information. Therefore, power consumption can be reduced accordingly.

  Further, the C station that has received the CTS addressed to the A station transmitted from the B station, for example, has a power reduction period between the end of receiving the CTS and the end of receiving the ACK corresponding to the CTS as described above. Then, it is possible to prepare for the reception of the next RTS, CTS, etc., and it is possible to suppress reception omission.

  Also, the C station that has received the CTS addressed to the A station transmitted from the B station sets the power reduction period to end slightly before the packet transmission prohibition period, so that the RTS or It is possible to prepare for reception of CTS or the like.

Next, another example of power consumption suppression in the wireless device according to the embodiment of the present invention will be described.
FIG. 3 is a diagram illustrating another example of power consumption suppression in the wireless device according to the embodiment of the present invention. Note that the communication example between stations A and C shown in FIG. 3 is basically the same as the communication example between stations A and C shown in FIG. 1, but only when a data packet is transmitted from station A. The station is different from the communication example between the stations A to C shown in FIG. 1 in that it is assumed that the station A can be received.

  First, as shown in FIG. 3C, the station C receives the data packet transmitted from the station A, and refers to the transmission destination address of the data packet added to the header of the data packet.

  Next, when the station C confirms that the data packet received by the transmission destination address is a data packet addressed to another station, the communication scheduled period information (for example, data at the station B) added to the header of the data packet is also obtained. 3), a packet transmission prohibition period as shown in FIG. 3 (d) is obtained based on the reception end timing of the packet header to the reception end timing of ACK in the station A). Ban.

  Then, the C station sets the obtained packet transmission prohibition period as a power reduction period, and stops or reduces power supply to the power reduction period RF unit, the BBP unit, and the like. Station C may set the power reduction period to end slightly before the packet transmission prohibition period, as shown in FIG.

  In this way, the C station that has received the data packet addressed to the B station transmitted from the A station stops power supply to some circuits such as the power reduction period RF unit and the BBP unit based on the scheduled communication period information, or Since it can be suppressed, power consumption can be suppressed accordingly.

  Further, the C station that has received the data packet addressed to the B station transmitted from the A station, for example, ends the reception of the ACK corresponding to the data packet from the end of the reception of the header of the data packet during the power reduction period as described above. When the period is up to the time, it is possible to prepare for the reception of the next RTS, CTS, or data packet, etc., and to suppress reception omission.

  In addition, the C station that has received the data packet transmitted from the A station and destined for the B station sets the power reduction period to end slightly before the packet transmission prohibition period. , CTS, or data packets can be prepared for reception.

Next, a method for setting the power reduction period in the wireless device of this embodiment will be described.
FIG. 4 is a diagram illustrating an example of a method for setting a power reduction period. FIG. 4 shows a method for setting the power reduction period in station C shown in FIG. FIG. 4A shows an RTS frame format. FIG. 4B is a flowchart showing the operation of generating a power reduction period in station C.

  First, as shown in FIG. 4A, the frame format of the RTS 40 includes, for example, a header area 41 and an FCS (Frame Check Sequence) area 42. The header area 41 includes, for example, a duration area 43 and a transmission destination address area 44 in which an address of a wireless terminal that is a transmission destination of the data packet is stored.

Next, the operation for generating the power reduction period in station C will be described.
As shown in FIG. 4B, first, in step S1, the station C receives the RTS 40. Next, in step S2, the station C refers to the transmission destination address from the transmission destination address area 44 of the RTS 40. It is determined whether or not the own address matches the destination address.

  Then, if the own address matches the transmission destination address (Yes in Step S2), in Step S3, the C station prepares to receive the data packet and transmits CTS and the like.

  On the other hand, when the address and the destination address do not match (No in step S2), in step S4, the station C refers to the communication schedule period information from the duration area 43, and based on the communication schedule period information, Set the counter value.

Next, in step S5, the station C starts counting down the counter and stops or reduces power supply to the FR unit, the BBP unit, and the like while the counter is counting down.
In step S6, when the count-down of the counter is completed, the station C returns the power supply to the FR unit, the BBP unit, etc., and prepares for reception of the RTS, CTS, or data packet.

Next, the countdown start timing of the counter will be described.
Fig.5 (a) has shown the specific example of the electric power reduction period produced | generated in the C station shown in FIG.

In FIG. 5A, the reception end timing of the data packet at station C is the countdown start timing.
As described above, in the example of the power consumption control of the station C shown in FIG. 5A, the period from the reception end timing of the header area 51 of the data packet 50 to the reception end timing of the FCS area 53 of the data packet 50 is followed. A period combined with the period indicated by the counter value is defined as a power reduction period.

  In the embodiment shown in FIG. 1 and FIG. 2, the packet transmission prohibition period is configured to be a power reduction period. As in FIG. 5A, a predetermined time from the reception end timing of the RTS or CTS header area. A period obtained by combining the period until the lapse of time and the period indicated by the counter value may be set as the power reduction period.

The start time and end time of the counter may be arbitrarily settable.
Next, the radio apparatus according to this embodiment will be described.
FIG. 5B is a diagram illustrating functional blocks constituting the wireless device of the present embodiment.

  As shown in FIG. 5B, the wireless device 60 of the present embodiment includes, for example, a wireless communication unit (Access Point), a mobile terminal device (notebook personal computer, PDF (Personal Digital Assistant)), and the like. For example, an RF unit 61, a BBP unit 62, and a MAC unit 63.

  For example, the operation for generating the power reduction period illustrated in FIG. 4B is performed by the MAC unit 63 illustrated in FIG. 5B, and a power reduction control signal is output from the MAC unit 63 to the RF unit 61 and the BBP unit 62. Accordingly, the power supply to the power reduction period RF unit 61 and the BBP unit 62 as shown in FIGS. 1 to 3 is stopped or reduced.

Next, consider a case where data packets are divided and transmitted continuously by fragmentation.
FIG. 6 is a diagram illustrating an example of power consumption suppression of the wireless device when data packets are divided and transmitted continuously. FIG. 6A shows an example of packet transmission timing and packet reception timing of A station having data addressed to B station. FIG. 6B shows an example of packet transmission timing and packet reception timing of station B. FIG. 6C shows an example of the packet reception timing of the C station when the A station can be received for the first time when the divided data packet is transmitted in the A station. FIG. 6D shows the start timing (upward arrow) and end timing (downward arrow) of the packet transmission prohibition period (NAV) of station C. FIG. 6E shows the power supply stop timing (downward arrow) and the power supply restart timing (upward arrow) to the RF unit and BBP unit of the C station.

  As shown in FIGS. 6A and 6B, in order to transmit a data packet from the A station to the B station, first, the RTS is transmitted from the A station, and the CTS is transmitted from the B station to the RTS. A data packet is transmitted from station A to the CTS. When transmitting this data packet, station A divides the data packet and transmits it continuously.

At this time, the station C sets a power reduction period corresponding to each divided data packet, as shown in FIGS.
However, as shown in FIG. 6, when the transmission interval of each data packet is short and each power reduction period corresponding to each data packet is also short, the power supply control unit (in the example of FIG. 5B, the MAC unit 63) The power consumed for obtaining the power reduction period in the case of the data packet increases according to the number of data packet divisions, even if the RF unit or the BBP unit (RF unit 61 or BBP unit 62 in the example of FIG. 5B), etc. Even if the power consumption is suppressed, the power consumption of the entire wireless device may increase.

  Therefore, a method is considered in which the power reduction period is compared with the predetermined period, and the power supply to the power reduction period RF unit, the BBP unit, or the like is stopped or reduced only when the power reduction period is longer than the predetermined period.

FIG. 7A is a diagram illustrating a configuration of packet communication in the A station, the B station, and the C station.
As shown in FIG. 7A, it is assumed that the stations A to C can transmit and receive packets such as RTC, CTS, and data packets to each other.

FIG. 7B shows an example of a frame format of data packets transmitted / received to / from each of the stations A to C shown in FIG. 7A.
As shown in FIG. 7B, the frame format of the data packet 50 includes, for example, a header area 51, a data area 52, and an FCS (Frame Check Sequence) area 53. The header area 51 includes, for example, a duration area 54 and a transmission destination address area 55 in which the address of the wireless terminal that is the transmission destination of the data packet 50 is stored.

  FIG. 7C is a flowchart showing the operation of generating a power reduction period in station C shown in FIG. Here, the generation operation of the power reduction period in the C station when the A station transmits the data packet 50 addressed to the B station or the data packet 50 addressed to the C station will be described.

  As shown in FIG. 7C, first, in step ST1, the station C receives the data packet 50. Next, in step ST2, the station C obtains a destination address from the destination address area 55 of the data packet 50. With reference to this, it is determined whether or not the own address matches the transmission destination address.

  If the own address matches the transmission destination address (Yes in step ST2), the station C receives the data packet 50 as a data packet addressed to itself in step ST3 and receives an ACK corresponding to the data packet 50 as A. Reply to the station.

  On the other hand, if the address and the destination address do not match (No in step ST2), the station C refers to the communication schedule period information from the duration area 54 in step ST4, and based on the communication schedule period information, Set the counter value.

  Next, in step ST5, the station C determines whether or not the counter value is greater than or equal to a threshold value. The threshold value may be set in consideration of the power consumption of the entire wireless device when receiving a packet.

  If it is determined that the counter value is not equal to or greater than the threshold value (No in step ST5), in step ST6, the station C does not stop or reduce the power supply to the RF unit, the BBP unit, etc. The station C continues to supply power to the RF unit, the BBP unit, etc., and prepares to receive RTS, CTS, or data packets.

  On the other hand, if it is determined that the counter value is equal to or greater than the threshold value (Yes in step ST5), in step ST7, the station C starts counting down the counter and supplies power to the FR unit, the BBP unit, etc. during the counter countdown Stop or reduce.

  In step ST8, when the count-down of the counter is completed, the station C returns the power supply to the FR unit, the BBP unit, etc. to prepare for reception of the RTS, CTS, or data packet.

  As a result, when the data packet addressed to the other station is divided and transmitted by fragmentation, and the ACK and ACK periods are shortened, the wireless device that has received the divided data packet addressed to the other station is a part of the wireless device. Since it is possible not to stop or suppress the power supply to this circuit, it is possible to suppress the power consumed for the control to stop or suppress the power supply to some circuits of the wireless device.

  In the above-described embodiment, power reduction control in data packet communication using RTS / CTS is shown. However, for example, the present invention may be applied to data packet communication not using RTS / CTS.

It is a figure which shows an example of the power consumption suppression in the radio | wireless apparatus of embodiment of this invention. It is a figure which shows the other example of the power consumption suppression in the radio | wireless apparatus of embodiment of this invention. It is a figure which shows the other example of the power consumption suppression in the radio | wireless apparatus of embodiment of this invention. It is a figure which shows an example of the setting method of an electric power reduction period. It is a figure which shows the specific example of an electric power reduction period. It is a figure which shows an example of the power consumption suppression in the radio | wireless apparatus when the data packet divided | segmented by fragmentation is transmitted. It is a figure which shows an example of the setting method of an electric power reduction period.

Explanation of symbols

40 RTS
41 Header area 42 FCS area 43 Duration area 44 Destination address area 50 Data packet 51 Header area 52 Data area 53 FCS area 54 Duration area 55 Destination address area 60 Wireless device 61 RF section 62 BBP section 63 MAC section

Claims (4)

A wireless device used in a wireless communication network in which packet communication is performed,
When a packet transmitted / received between other wireless devices is received, a power reduction period is obtained based on scheduled communication period information indicating a scheduled use period of a wireless line between the other wireless devices added to the packet, A wireless device, wherein power supply to a part of circuits of the wireless device is stopped or suppressed during a power reduction period. The wireless device according to claim 1,
The packet transmitted / received between the other wireless devices is a transmission request packet indicating that it wants to transmit a data packet, a reception preparation completion packet indicating that reception preparation of the data packet is completed, or the data packet. A wireless device characterized. The wireless device according to claim 1 or 2, wherein
The wireless device, wherein the power reduction period ends before a packet transmission prohibition period obtained based on the scheduled communication period information. The wireless device according to any one of claims 1 to 3,
When the power reduction period is longer than a predetermined period, the wireless apparatus stops or suppresses power supply to some circuits of the wireless apparatus during the power reduction period.

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