JP2005223793A - Power-saving method of portable radio terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save power in the reception standby mode of a portable radio terminal operated by an infrastructure BSS (Basic Service Set) under the control of the access point of a CSMA (Carrier Sense Multiple Access) wireless LAN. <P>SOLUTION: The portable radio terminal 1 causes a frame detector 29 to start up a timer 31 when the reception of a data frame is completed. The timer 31 controls a reception unit power supply clock control unit 33 from the time immediately after the startup until the timeout based on contents of a timeout time storage register 32, and stops the operation of all blocks of a wireless LAN reception unit 42. Thus, the power consumed by the LAN reception unit 42 is reduced. After the timeout of the timer 31, the wireless LAN reception unit 42 restores to the reception standby mode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a portable wireless terminal that operates a CSMA (Carrier Sense Multiple Access) wireless LAN in an infrastructure BSS (Basic Service Set) under the umbrella of an access point.

  In recent years, wireless LAN technology has been dramatically developed, and wireless LAN access points have been installed not only in companies but also for public communications. As a result, the number of cases where wireless LAN, which has been mainly used by personal computers, is used in portable wireless terminals that are smaller than personal computers is increasing.

  In such a portable wireless terminal, in order to extend the battery life when going out, it is important to save power in the wireless LAN interface, particularly in the wireless LAN reception standby mode. . Conventionally, in a method of performing power saving when waiting for reception of a wireless LAN, in the reception processing in the wireless LAN interface unit, only the wireless reception unit and the received wireless level determination unit are always activated, and the level There is a method of activating other parts of reception processing such as a demodulation unit and a frame detection unit when the determination unit exceeds a threshold (see, for example, Patent Document 1).

  The operation of the power saving method in such a conventional portable wireless terminal will be described with reference to FIG. In FIG. 5, 5 is a conventional portable radio terminal. Reference numeral 24 denotes an antenna that performs wireless transmission and reception. Reference numeral 21 denotes a wireless LAN frame assembly unit. A modulation unit 22 modulates the frame assembled by the frame assembly unit 21. Reference numeral 23 denotes a wireless transmission unit that wirelessly transmits the output of the modulation unit 22 and transmits it via the antenna 24. Reference numeral 41 denotes a wireless LAN transmission unit. The wireless LAN transmission unit 41 includes a frame assembly unit 21, a modulation unit 22, and a wireless transmission unit 23. Reference numeral 25 denotes a radio reception unit that receives radio input via the antenna 24. Reference numeral 26 denotes a reception level determination unit that determines the wireless level received by the wireless reception unit 25. Reference numeral 28 denotes a demodulator that demodulates the radio received by the radio receiver 25. A frame detection unit 29 detects a wireless LAN frame from the output of the demodulation unit 28 and analyzes the contents of the frame. 43 is a wireless LAN receiver. The wireless LAN reception unit 43 includes a wireless reception unit 25, a reception level determination unit 26, a demodulation unit 28, and a frame detection unit 29. Reference numeral 27 denotes a receiver power supply clock controller. Whether the reception unit power supply clock control unit 27 operates by controlling the input of the power supply or the clock to all blocks of the wireless LAN reception unit 43 except the wireless reception unit 25 and the reception level determination unit 26. Or control whether to stop.

  In FIG. 5, when the reception level determination unit 26 determines that the wireless level received by the wireless reception unit 25 exceeds the threshold value, the reception level determination unit 26 controls the reception unit power supply clock control unit 27 to control the demodulation unit 28 and the frame detection unit. 29, etc., all the blocks of the wireless LAN receiving unit 43 are operated, and the received radio wave is demodulated and the wireless LAN frame is detected. However, if the reception level determination unit 26 determines that the wireless level received by the wireless reception unit 25 does not exceed the threshold value, the reception level determination unit 26 controls the reception unit power supply clock control unit 27 to perform wireless communication among the wireless LAN reception unit 43. All blocks except the receiving unit 25 and the receiving level determining unit 26 are stopped. With this operation, it is possible to eliminate wasteful power consumption when waiting for reception of a wireless LAN, so that power saving can be achieved.

In FIG. 5, the wireless LAN transmission unit 41 is activated when there is a wireless LAN frame to be transmitted, including a response (ACK) to reception, and stops operating when there is no wireless LAN frame to be transmitted.
Japanese Patent No. 2700000 (page 5, FIG. 1)

  However, in the conventional wireless power saving method of the portable wireless terminal, the wireless LAN interface unit always activates two blocks of the wireless reception unit and the reception level determination unit. For this reason, it is necessary to always supply power to the radio reception unit and the reception level determination unit. For this reason, there is a problem that wasteful power consumption is consumed in the wireless LAN interface unit, particularly when the arriving frames are sporadic.

  The present invention solves the above-described conventional problems, and particularly when the mobile wireless terminal is operated in an infrastructure BSS under the access point and the frame arriving at the mobile wireless terminal is sporadic, the mobile wireless terminal An object of the present invention is to reduce the power consumption of the wireless LAN interface unit.

  In order to achieve this object, the power saving method for a portable wireless terminal according to the present invention operates the wireless LAN receiving unit of the portable wireless terminal by operating the input power supply or clock in the wireless LAN receiving unit. Alternatively, a receiver power clock controller that switches whether to stop, a timer that stops the wireless LAN receiver during timer operation through the receiver power clock controller, a timeout time storage register that stores a timeout time of the timer, A frame detection unit that detects a wireless LAN frame included in the wireless LAN reception unit and activates the timer in the case of the data frame addressed to the portable wireless terminal, and the frame detection unit detects the data frame addressed to the portable wireless terminal. Then, whether the reception processing of the data frame is completed by the timer Until the time stored in said time-out time storage register has elapsed, the reception power clock control unit stops all operations of the wireless LAN receiver.

  Further, in the access point, when transmitting a plurality of data frames addressed to the portable radio terminal, the transmission time interval between the data frames is always set longer than the time stored in the timeout storage register, whereby the portable radio terminal Prevents data frame reception loss.

  In the portable wireless terminal according to the present invention, the portable wireless terminal includes the wireless receiver and the wireless receiver from the completion of the data frame reception processing until the time stored in the timeout time storage register elapses. All operations of the LAN receiving unit are stopped, and power saving of the wireless LAN receiving unit is achieved. As a result, particularly when the frame arriving at the portable wireless terminal is sporadic, it is possible to efficiently save power in the wireless LAN interface unit of the portable wireless terminal.

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

(Embodiment 1)
FIG. 1 shows a portable radio terminal according to Embodiment 1 of the present invention. In FIG. 1, the same components as those in FIG.

  In FIG. 1, reference numeral 1 denotes a portable wireless terminal. Reference numeral 42 denotes a wireless LAN receiver. The wireless LAN receiver 42 includes a wireless receiver 25, a demodulator 28, and a frame detector 29. Reference numeral 33 denotes a receiving unit power supply clock control unit. The reception unit power supply clock control unit 33 controls whether all the blocks included in the wireless LAN reception unit 42 are operated or stopped by controlling the power supply or clock input. Reference numeral 31 denotes a timer for controlling the receiver power supply clock controller 33. A time-out time storage register 32 stores the time-out time of the timer 31.

  Next, the operational environment of the first embodiment will be described with reference to FIG.

  Reference numeral 2 denotes an access point. Reference numeral 3 denotes an infrastructure BSS under the control of the access point 2. Reference numeral 4 denotes an external network connected to the access point 2. The portable wireless terminal 1 operates under the infrastructure BSS 3 and communicates with the access point 2.

  Next, the operation in the first embodiment will be described with reference to FIG.

  When the access point 2 transfers the data frame 101 addressed to the portable wireless terminal 1 received from the network 4 to the wireless LAN of the infrastructure BSS 3 as the data frame 111, the portable wireless terminal 1 operates the wireless LAN receiving unit 42. The data frame 111 is received. At this time, the wireless LAN unit of the portable wireless terminal 1 consumes power 121 for frame reception.

  When the portable wireless terminal 1 completes the reception of the data frame 111, the frame detection unit 29 starts the timer 31. The timer 31 loads the value of the timeout time storage register 32 (the value 133 in FIG. 3 is written) as an initial value. The timer 31 controls the receiving unit power supply clock control unit 33 immediately after starting up until it times out, and stops the operation of all the blocks of the wireless LAN receiving unit 42. As a result, the portable wireless terminal 1 can suppress the power consumption of the wireless LAN unit to only the power consumption of the timer 31 immediately after the data frame 111 is received and until the timeout time 133 elapses. It is possible to reduce the power consumption of the wireless LAN unit compared to the normal reception standby power consumption 124 (123 in FIG. 3). However, since the portable wireless terminal 1 has to transmit the ACK frame 112 for the data frame 111 to the access point 1, the wireless LAN unit consumes power 122 for transmitting the ACK frame 112. After the timeout time 133 has elapsed, the wireless LAN receiver 42 enters a reception standby state, and waits for the arrival of the next frame 115 from the access point 2 while consuming power 124 in the wireless LAN unit.

  With such a configuration, in the portable wireless terminal, when the arriving frame is sporadic, the reception waiting process in the wireless LAN unit is omitted for a certain time from the arrival of the frame addressed to the portable wireless terminal. The power consumption required for the wireless LAN receiver can be reduced. Thereby, power saving of the portable wireless terminal can be achieved.

(Embodiment 2)
The portable radio terminal according to the second embodiment of the present invention is the same as FIG. 1 as the portable radio terminal according to the first embodiment.

  The operation mode in the second embodiment is also the same FIG. 2 as the operation mode in the first embodiment.

  Next, the operation in the second embodiment will be described with reference to FIG. 4, the same reference numerals are used for the same indicators as those in FIG. 3, and description thereof is omitted.

  The access point 2 transfers the data frame 101 addressed to the portable wireless terminal 1 received from the network 4 to the wireless LAN of the infrastructure BSS 3 as the data frame 111, and then transmits the next data frame 106 addressed to the portable wireless terminal 1 from the network 4. The following operation is performed when the data frame 111 is received when the time interval shorter than the time-out time 133 of the timer 31 of the portable terminal device 1 has elapsed since the transmission of the data frame 111 is completed. At this time, the access point 2 temporarily holds the transfer of the data frame 106 to the wireless LAN of the infrastructure BSS 3 and buffers it inside the access point 2. Then, after the transmission of the data frame 111 is completed and the timeout time 133 of the timer 31 elapses, the buffered data frame 106 is transferred to the wireless LAN of the infrastructure BSS 3 as the data frame 116. In this manner, the time interval of the data frame transmitted from the access point 2 to the portable wireless terminal 1 is set to the timeout time 133 of the timer 31 or more. Thereby, after the reception process of the data frame 111 is completed in the portable wireless terminal 1, the data frame addressed to the portable wireless terminal 1 from the access point 2 while the operation of the wireless LAN receiving unit 42 is stopped by the timer 31. Can be avoided.

  With such a configuration, even if a data frame arrives temporarily at a short time interval from the network to the portable wireless terminal that has achieved power saving in the first embodiment, the data frame is received without loss. can do.

(Embodiment 3)
The portable radio terminal according to the third embodiment of the present invention is the same as FIG. 1 as the portable radio terminal according to the second embodiment.

  The operation mode in the third embodiment is also the same as FIG. 2 as the operation mode in the second embodiment.

  Next, the operation in the third embodiment will be described.

  The portable wireless terminal 1 is operating in the infrastructure BSS3 under the access point 2, and for example, transmits to the access point 2 control information for changing the contents of the timeout time storage register 32 of the timer 31 in a frame. The contents of the timeout time storage register 32 are changed in synchronization with the access point 2. Accordingly, for example, when the mobile wireless terminal 1 receives relatively low rate data such as voice information, the value of the timeout time storage register 32 is increased, and the time during which the wireless LAN receiving unit 42 is stopped is lengthened. In order to increase the degree of power saving or to receive relatively high rate data such as image information in the portable wireless terminal 1, for example, the value of the timeout time storage register 32 is decreased and the wireless LAN receiving unit By shortening the time during which 42 is stopped, the degree of power saving can be reduced.

  With such a configuration, the arrival of the received frame can be performed by changing the degree of power saving according to the time change of the arrival interval of the data frame for the portable wireless terminal that has achieved power saving in the second embodiment. Power saving suitable for the interval, that is, the reception rate can be performed.

  The present invention is particularly effective in a portable wireless terminal that receives frames that arrive at almost constant time intervals, such as voice information and image information.

The figure of the wireless LAN transmission / reception part of the portable wireless terminal in this invention Diagram of operation mode of portable wireless terminal in the present invention FIG. 3 is a diagram of frame flow and wireless LAN unit power consumption of portable information terminal 1 according to Embodiment 1 of the present invention. The figure of the flow of the frame in Embodiment 2 of this invention, and the wireless LAN part power consumption of the portable information terminal 1 Diagram of wireless LAN transmission / reception unit of portable wireless terminal in conventional example

Explanation of symbols

1 Mobile wireless terminal 2 Access point 3 Access point 2 Infrastructure BSS
4 Network 5 Portable Wireless Terminal 21 Frame Assembly Unit 22 Modulation Unit 23 Radio Transmission Unit 24 Antenna 25 Radio Reception Unit 26 Reception Level Determination Unit 27 Reception Unit Power Supply Clock Control Unit 28 Demodulation Unit 29 Frame Detection Unit 31 Timer 32 Timeout Time Storage Register 33 Reception unit power supply clock control unit 41 Wireless LAN transmission unit 42 Wireless LAN reception unit 43 Wireless LAN reception unit 101 Data frame addressed to portable wireless terminal 1 105 Data frame addressed to portable wireless terminal 1 106 Data frame addressed to portable wireless terminal 1 111 Data frame 112 ACK Frame 115 Data frame 116 Data frame 121 Wireless LAN unit power consumption for receiving data frame 111 122 Wireless LAN unit power consumption for transmitting ACK 112 123 Wireless when wireless LAN transmitting / receiving unit is stopped Wireless LAN unit power 125 data frame 115 wireless LAN unit power consumption 133 timeout for the wireless LAN unit power 126 data frame 116 received for the reception during AN unit power consumption 124 frame reception waiting

Claims (3)

In a portable wireless terminal operating a CSMA (Carrier Sense Multiple Access) wireless LAN in an infrastructure BSS (Basic Service Set) under the access point, the power supply or clock input to all of the wireless LAN receiving units A receiver power supply clock controller that switches between operating and stopping the wireless LAN receiver; and
A timer that stops the wireless LAN receiver during timer operation through the receiver power supply clock controller;
A timeout time storage register for storing a timeout time of the timer;
A frame detection unit included in the wireless LAN reception unit for detecting a wireless LAN frame and starting the timer in the case of the data frame addressed to the portable wireless terminal;
When the frame detection unit detects the data frame addressed to the portable wireless terminal, the reception power supply clock control is performed by the timer until the time stored in the timeout time storage register elapses after the reception process of the data frame is completed. A power saving method for a portable wireless terminal, characterized in that the unit stops all operations of the wireless LAN receiving unit to save power in the wireless LAN receiving unit. When transmitting a plurality of data frames addressed to the portable wireless terminal, the access point always leaves a transmission time interval between data frames more than the time stored in the timeout storage register. The method for reducing power consumption of a portable wireless terminal according to claim 1, wherein reception loss of data frames is prevented. Control information is transmitted and received between the access point and the mobile wireless terminal in the previous period to change the value of the timeout storage register, thereby saving the mobile wireless terminal according to the time change of the arrival interval of data frames. The power saving method for a portable radio terminal according to claim 2, wherein the degree of power conversion is changed.

Images