KR20140063402A - Access point apparatus and method for power saving in wireless device supporting wifi tethering services - Google Patents

Abstract

A method for saving power of a wireless device supporting a Wi-Fi tethering service comprises the steps of broadcasting, through an access point device, a beacon frame; setting a timer according to a CFP counter value relevant to the beacon frame; starting buffering and checking whether a terminal that has performed a power saving notification process exists; checking the number of frames according to the timer or the number of buffered frames based on whether the terminal exists; switching a mode of the terminal from a sleep mode to an active mode according to the checking result; and stopping the buffering after switching the mode of the terminal to the active mode and entering into a competition period.

Description

TECHNICAL FIELD [0001] The present invention relates to an access point apparatus and a method thereof for reducing power consumption of a wireless device supporting a Wi-Fi tethering service,

The present invention relates to an access point apparatus and method for power saving of a wireless device supporting a Wi-Fi tethering service.

WiFi Tethering is a feature that is widely supported in commercial smartphones recently, and a mobile terminal capable of connecting to the Internet via 3G / 4G provides Internet service using WiFi to other terminals that can not use the Internet service. You are a skill.

Such a mobile terminal supporting WiFi tethering is called a Mobile Software Access Point (MSAP).

FIG. 1 shows an example of WiFi tethering in which two terminals STA1 and STA2 receive Internet service through a terminal STA3 corresponding to a mobile software access point (MSAP). Here, a mobile software access point (MSAP) can connect to the Internet using 3G / 4G wireless communication technologies such as high speed downlink packet access (HSDPA) and long term evolution (LTE).

802.11 wireless LAN is IEEE standard technology that has been widely used for many wireless communication users for a long time. There are two modes of wireless LAN: Infrastructure Mode and Adhoc Mode. In the infrastructure mode, data exchange between two terminals in the same Basic Service Set (BSS) is performed through a repeater called an access point in the middle. On the other hand, in the ad hoc mode, direct communication is possible between the two terminals.

The medium access method of 802.11 based WLAN is divided into DCF (Distributed Coordination Function) and PCF (Point Coordination Function).

A DCF based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) is a medium access method used during a contention period (CP). A UE using a DCF transmits a frame And contention. In contrast, the PCF is a media access method used in a contention free period (CFP). The access point sequentially allocates resources to each terminal in a polling manner, and the terminal transmits a data frame It is a way to communicate.

Next, a description will be given of an operation procedure of the access point obtaining a channel necessary for performing the PCF.

First, the access point controls the other terminals not to attempt to access the channel while the PCF operation proceeds, and can successfully perform the operation process of the PCF. To this end, the access point and the terminal in the standard operate as follows.

If the access point supports the PCF mode, the beacon frame broadcasted by the access point includes a CFP parameter set.

The CFP parameter set consists of four major fields (CFPCount, CFPPeriod, CFPMaxDuration, CFPDurRemaining). Among these, CFPMaxDuration and CFPDurRemaining are fields for specifying a time to be used as a contention-free period, CFPMaxDuration represents a maximum allowable value of contention-free period, and CFPDurRemaining represents a value of contention-free period set in the current beacon frame. And CFPCount is the number of beacon frames to be transmitted until the next non-contention period. That is, if CFPCount is 0, it means that the non-contention period starts immediately after sending the beacon frame. The UEs set their NAV (Network Allocation Vector) to the CFPMaxDuration value when the non-contention period is scheduled, that is, when the CFPCount of the beacon frame to be received is zero. The terminal acquires the CFPMaxDuration value through the beacon frame or the probe response frame received previously. Since the CFPCount value is reduced by 1 for each beacon frame, CFPCount can be predicted even if the beacon frame is not received, so that it is possible to know when the non-contention period is scheduled. If the beacon frame is successfully received in this period and the CFPCount value is found to be 0, the UE resets its NAV using the CFPDurRemaining value of the CF parameter set. In the 802.11 standard, an access point can acquire a channel during CFPDurRemaining, since the terminal will not attempt to transmit to the channel until the NAV expires. This period is referred to as a contention-free period, and the access point performs data frame exchange through polling sequentially with terminals supporting the PCF (CF-Pollable terminals) during this period. After completing the polling process, the access point broadcasts the CF-End frame to inform the end of the PCF operation. The UEs receiving the CF-End frame set their NAVs to 0 and enter the competition period. The UEs can participate in the data frame transmission according to the DCF operation process.

Next, a power saving mode is included in the IEEE 802.11 standard technology for reducing the power of a terminal wasted in an idle time that does not use a channel. A terminal supporting the power saving technique utilizes two modes, an active mode and a sleep mode. A terminal in the active mode means a state in which the wireless interface is turned on so as to enable data communication with an access point (infrastructure mode) or another terminal (ad hoc mode). On the other hand, a sleep mode terminal refers to a state in which the wireless interface is turned off to reduce power consumption, and consumes lower power than a state in which the wireless interface is turned on. A terminal supporting the power saving technique can switch to the sleep mode because of a difference in data exchanged with an access point or another terminal or the like. Before switching to the sleep mode, the terminal notifies the access point to switch to the sleep mode, and receives a response message to the access point. An access point that is aware that a particular terminal switches to the sleep mode starts buffering for a data frame destined for that terminal. The terminal in the sleep mode transitions to the active mode periodically (e.g., a beacon period) to check the beacon frame and determine whether there is data to be received from the access point. The beacon frame has a Traffic Indication Map (TIM) field, where each bit in the corresponding field is mapped to one of the currently connected terminals. The access point sets the corresponding bit of the TIM field to 1 when the access point is buffering one or more data frames destined for a specific terminal. If there is a data frame to be received by the terminal, the PS_Poll management frame is transmitted to the access point to indicate that the terminal has switched to the active mode. Thereafter, the access point transmits one data frame to the corresponding terminal, and the terminal responds with an ACK frame. At this time, if the access point has more data frames to its terminal in its buffer, the access point sets the MD (more data) bit of the frame control field in the MAC header of the data frame to 1. If the MD bit is set to 1, the UE re-performs the process of transmitting the PS_Poll management frame to receive the next data frame. After receiving all the buffered data (the MD bit of the last data frame sent by the access point to the terminal is set to 0), the terminal sets the PM bit of the frame control field in the ACK frame transmitted in response to the last data frame to 1 To the access point, and enters the sleep mode again. In this manner, the terminal switches to the active mode only when there is a data frame to receive the data frame, and receives data, thereby reducing power consumption of the terminal.

However, the IEEE 802.11 standard mentions that access points are not allowed to enter sleep mode using power saving techniques. This is because the conventional access point always uses the main power so that the reduction of power consumption is not a big issue. However, due to the emergence of portable devices that use battery power and the support of mobile software access points (MSAP) functions of these devices, it is necessary to reduce the power consumption of access points. However, applying power saving techniques for terminals, described in the IEEE standard, to mobile software access points is limited. The reason for this is that the current standard power saving technique is that the access point does not have an operation process informing the terminal to enter the sleep mode. When the access point enters the sleep mode without the sleep mode entering notification process, the UE does not know the sleep mode and thus the UE experiences a problem of loss of the uplink data frame transmitted to the access point.

An object of the present invention is to provide an access point apparatus and method for power saving of a wireless device supporting Wi-Fi tethering service.

According to an aspect of the present invention, there is provided a method for reducing power consumption of a wireless device supporting a Wi-Fi tethering service,

The access point device broadcasting a beacon frame; Setting a timer according to a CFP counter value corresponding to the beacon frame; Starting buffering and confirming whether a terminal performing the power saving notification process exists; Checking the number of frames according to the timer or checking the number of buffered frames according to presence or absence of the terminal; Switching the mode of the corresponding terminal from the sleep mode to the active mode regardless of the timer according to the result of the checking; And stopping the buffering after switching the mode of the corresponding terminal to the active mode, and entering the competition period.

At this time, the broadcasting is performed by setting the B12 reserved bit in the capability information field of the beacon frame to 1.

In this case, the setting of the timer may include: checking the CFP counter value included in the CFP parameter set of the beacon frame; If the CF-Pollable terminal is within the setting range, checking whether the CF-Pollable terminal exists within the setting range when the CFP counter value is equal to zero; ; And setting the timer to the remaining time after the CF-Pollable terminal performs the PCF operation.

In this case, the power saving notification process may include receiving the power saving support notification frame from the access point device; And generating the power saving support confirmation frame using the confirmation message for the power saving support announcement frame and transmitting the power save support confirmation frame to the access point device.

In this case, the method further includes determining whether the access point device uses the power saving mode.

In this case, the step of determining whether to use the power saving mode may include determining a channel use level of a BBS that the access point is servicing with respect to a contention period before broadcasting the beacon frame; Comparing the degree of channel use with a threshold value; And using the power saving mode when the channel usage degree is smaller than a threshold value.

In this case, if the CFP counter value corresponding to the beacon frame corresponds to zero, the step of setting the timer includes checking whether the PCF supporting terminal exists within the set range. Controlling the PCF supporting terminal to perform a PCF operation when the PCF supporting terminal exists; And setting a timer to a remaining time after the PCF supporting terminal performs the PCF operation and entering a sleep mode.

In this case, if there is a terminal that has performed the power saving notification process, the switching may include switching the buffered frame to a first buffered frame, And switches to the active mode when the delay time exceeds a threshold value.

If the number of frames buffered before the expiration of the timer exceeds a frame threshold value, the switching to the active mode is performed. .

Also, a method for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention

Receiving a beacon frame broadcasted by an access point device; Determining whether a power saving notification process has been performed with the access point apparatus when a power saving bit is set in the beacon frame; Confirming a CFP counter value corresponding to the beacon frame when the power saving notification process is performed; Setting a timer according to the CFP counter value and starting buffering of the beacon frame; Switching from an active mode to a sleep mode when the buffering starts and switching from the sleep mode to the active mode when the timer expires; And stopping the buffering of the beacon frame, starting transmission of the buffered beacon frame according to the DCF operation procedure, and entering into a contention period.

In this case, before the step of determining whether the power saving notification process has been performed, it is checked whether the power saving bit is set through the probe response or association response frame in addition to the beacon frame.

At this time, the power saving notification process may include a step of the terminal accessing the access point apparatus; The terminal generates a power saving support notification frame and transmits the power saving support notification frame to the access point to notify participation in a power saving operation; And receiving a power saving support confirmation frame corresponding to the power saving support announcement frame from the access point apparatus.

In this case, if the CFP counter value does not correspond to zero, the mobile station enters a contention period and transmits the beacon frame to the access point apparatus according to a DCF operation procedure.

In this case, when starting the buffering, if the CFP counter value is zero, setting a network location vector value using a CFPDurRemaining value and checking whether the terminal itself corresponds to a PCF supporting terminal; And setting the timer according to a result of checking whether the terminal corresponds to the PCF supporting terminal.

In addition, an access point device for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention includes:

A transmitting unit for broadcasting a beacon frame; A timer setting unit for setting a timer according to a CFP counter value corresponding to the beacon frame; A buffering unit for buffering the beacon frame; A confirmation unit for checking whether there is a terminal that has performed the power saving notification process, checking the number of beacon frames according to the timer according to the presence or absence of the terminal, or checking the number of buffered beacon frames; A mode switching unit for switching the mode of the corresponding terminal from the sleep mode to the active mode regardless of the timer according to the result of the check; And a contention period entry unit for interrupting buffering after switching the mode of the corresponding terminal to the active mode and entering a contention period.

At this time, the transmitter sets the B12 reserved bit in the capability information field of the beacon frame to 1 and broadcasts it.

At this time, if the CFP counter value included in the CFP parameter set of the beacon frame corresponds to zero, and the CF-Pollable terminal has a preset range, the timer setting unit performs the PCF operation , And the CF-Pollable terminal performs the PCF operation and sets the timer to the remaining time.

In this case, when there is a terminal that has performed the power saving notification process, the mode switching unit determines that the number of frames to be buffered before the timer expires exceeds a frame threshold, and the delay of the first buffered frame among the buffered frames And switches to the active mode when the time exceeds the threshold value.

In this case, when the terminal performing the power saving notification process does not exist, the mode switching unit switches to the active mode when the number of frames buffered before the timer expires exceeds a frame threshold value do.

The present invention can realize a reduction in the power consumption of the Wi-Fi interface of the access point apparatus only through modification of the access point apparatus without requiring modification of the terminal. In addition, when the terminal is modified so as to recognize the operation of reducing the power consumption of the access point apparatus, the power consumption of the terminal can be reduced for the same period.

1 is a diagram illustrating an example of WiFi tethering in which two terminals are receiving Internet service through a terminal corresponding to a mobile software access point device.
2 is a diagram illustrating an environment for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention.
3 is a block diagram schematically illustrating a terminal for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention.
FIG. 4 is a flowchart illustrating an operation procedure of a terminal for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention.
5 is a diagram illustrating a power saving notification process according to an embodiment of the present invention.
FIG. 6 is a flowchart illustrating a process of periodically performing an access point apparatus according to an embodiment of the present invention to determine whether to use the power saving technique.
FIG. 7 is a view showing a competitive period and a non-competitive period according to an embodiment of the present invention.
8 is a configuration diagram schematically illustrating an access point apparatus for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention.
9 is a flowchart illustrating an operation procedure of an access point apparatus for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention.

The present invention will now be described in detail with reference to the accompanying drawings. Hereinafter, a repeated description, a known function that may obscure the gist of the present invention, and a detailed description of the configuration will be omitted. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

Hereinafter, a terminal, an access point, and a method for power saving of a wireless device supporting a Wi-Fi tethering service according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, the present invention uses an operation procedure of obtaining a channel necessary for performing a conventional PCF using a CFP parameter set of a beacon frame. The access point device that has acquired the channel in the standard exchanges data frames through polling sequentially with the terminals supporting each PCF, and then directly transmits the CF-End frame to enter the competition period. However, in the present invention, the access point that has acquired the channel transmits the CF-End frame immediately before the CFPDurRemaining expires after exchanging the data frame through the polling sequentially with the terminals supporting each PCF. By using this method, the access point device can enter the sleep mode for the remaining time (CFPDurRemaining, PCF operation process time), thereby realizing power saving of the access point device. During this period, the access point device buffers the downlink data frame. Only when the terminal can recognize the use of the power saving scheme by the access point apparatus, power saving for the same period is also possible. Similarly, during this period, the terminal buffers the uplink data frame.

2 is a diagram illustrating an environment for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention.

Referring to FIG. 2, the terminal 100 and the access point 200 are located in an environment for power saving of a wireless device supporting a Wi-Fi tethering service.

The access point device 200 supporting the power saving mode can announce that it supports the power saving operation process by broadcasting the B12 reserved bit in the capability information field of the beacon frame by setting it to 1. Here, setting the B12 reserved bit to 1 means that the access point device 200 supports an operation process for saving its own power.

Hereinafter, in the present invention, B12 reserved bits are referred to as AP power saving bits. In addition, an AP power saving bit may be set in the capability information field in another management frame (for example, a probe response, an association response frame, etc.) included in the capability information field to inform the terminal.

Next, the configuration of the terminal 100 and the operation procedure of the terminal 100 will be described in detail with reference to FIG. 2 and FIG.

3 is a block diagram schematically illustrating a terminal for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention. 4 is a flowchart illustrating an operation of a terminal for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention. 5 is a diagram illustrating a power saving notification process according to an embodiment of the present invention.

3, the terminal 100 includes a receiving unit 110, a configuration checking unit 120, a process performing unit 130, a count value checking unit 140, a timer setting unit 150, a buffering unit 160, A mode switching unit 170, and a competition period entry unit 180. [

The receiving unit 110 receives the broadcasting beacon frame (S301).

The setting confirmation unit 120 checks whether the AP power saving bit is set in the beacon frame received by the receiving unit 110 (S302). In addition to the beacon frame, the setting confirmation unit 120 can also check whether the AP power saving bit is set through a probe response or an association response frame.

If the AP power saving bit is set, the process execution unit 130 determines whether the power saving notification process (see FIG. 5) has been performed with the access point apparatus 200 (S303). If the process execution unit 130 has not performed the power saving notification process with the access point apparatus 200, the process execution unit 130 performs a power saving notification process (S304).

In the present invention, a new management frame (a power saving support notification frame, a power saving support confirmation frame) is defined to perform a power saving notification process. At this time, two of the reserved subtype values (0110, 0111) are used to define the additional management frame of the 802.11 standard.

Referring to FIG. 5, the terminal 100 accesses the access point 200 (S410).

The terminal 100 generates a power saving support notification frame and transmits the power saving support notification frame to the access point 200 (S420) to inform the user of participation in the power saving operation. At this time, the power saving support notification frame sets the subtype value to 0110.

The access point device 200 generates a power saving support confirmation frame with a confirmation message for the power saving support notification frame and transmits the power saving support confirmation frame to the corresponding terminal (S430). Here, the power saving support confirmation frame sets the subtype value to 0111. That is, the terminal that has received the power saving support confirmation frame can now reduce the power consumption by entering the sleep mode when the access point device performs power saving.

When the beacon frame is received (S301), the AP power saving bit is set to 1 (S302) in the beacon frame, and when the power saving notification process is performed with the access point apparatus, Confirms the CFP counter value (CFPCount) of the CFP parameter set in the beacon frame (Content Free Parameter Set).

More specifically, the count value check unit 140 determines whether the CFP counter value CFPCount corresponds to 0 (S305).

If the CFP counter value CFPCount does not correspond to 0, the count value check unit 140 enters a contention period and transmits a data frame to the access point 200 according to the DCF operation procedure.

If the CFP counter value CFPCount is equal to 0, the timer setting unit 150 sets a NAV (Network Allocation Vector) using the CFPDurRemaining value and checks whether the CF card is a PCF supporting terminal (CF-Pollable terminal) (S306).

If the timer setting unit 150 corresponds to the PCF supporting terminal (CF-Pollable terminal), the timer setting unit 150 performs the PCF operation (S307). At this time, the timer setting unit 150 performs a polling process with the access point.

The timer setting unit 150 sets a timer to set the sleep mode period (S308 and S309).

The timer value T set in steps S308 and S309 is CFPDurRemaining-t2 (t2: sifs + CF-END transmission time) when the terminal 100 does not support the PCF. In the case of a terminal supporting the PCF, since data frames must be exchanged through the polling process with the access point apparatus 200, the time required for the terminal to receive the polling, that is, the time t3 used for the polling process And the remaining time (T = CFPDurRemaining-t2-t3).

The buffering unit 160 starts buffering the frame (S310).

When buffering of the frame is started, the mode switching unit 170 switches from the active mode to the sleep mode (S311). The mode switching unit 170 checks whether the timer expires in the sleep mode (S312). If the timer expires, the mode switching unit 170 switches to the active mode again (S313).

When the buffering unit 160 is switched to the active mode, the buffering unit 160 stops buffering the frame (S314).

The contention period entry unit 180 starts the buffered frame transmission according to the DCF operation procedure, thereby entering the contention period (S315).

When the terminal 100 does not receive the beacon frame, it does not know the CF parameter set in the beacon frame and thus does not enter the sleep mode. That is, it is remembered that the operation of the terminal 100 is performed separately from the power saving mode of the terminal described in the IEEE 802.11 standard. A terminal that does not recognize that the access point 200 performs the power saving operation, i.e., the terminal that has not been modified, will not check the AP power saving bit of the beacon frame.

Next, a process performed periodically by the access point apparatus 200 to determine whether to use the power saving technique will be described in detail with reference to FIG.

FIG. 6 is a flowchart illustrating a process of periodically performing an access point apparatus according to an embodiment of the present invention to determine whether to use the power saving technique. FIG. 7 is a view showing a competitive period and a non-competitive period according to an embodiment of the present invention.

Referring to FIG. 7, the period corresponds to the beacon period (100 ms).

When only the DCF is used, all the periods are, for example, a period of competition such as periods 1 and 4 in FIG.

However, when the access point device determines to use the power saving mode, a part of the entire period is used as a contention-based basis for the power saving mode and the remaining is used as a competition period for data exchange, as in the period 2 and the period 3 of FIG. do.

The access point apparatus 200 determines the degree of channel use in the contention period, and determines the entry into the contention-free period for use of the power saving mode when the channel usage level is used below the threshold value.

For example, in FIG. 7, the access point apparatus 200 calculates the busy time ratio (BTR) of the BSS that it is servicing for the contention period (T1) before transmitting the beacon frame after the period 4, . Here, the BTR is calculated as shown in Equation (1).

[Equation 1]

In Equation (1), a is a value between 0 and 1, and BTR _old is a previous BTR value. BTR _cur is the current measured BTR value, which is the ratio of the time the channel is used for transmission of the frame in the measurement period.

Referring to FIG. 6, the access point device 200 calculates BTR _cur for the contention period (period 4) at time T1, for example, to determine whether to use the power saving mode in period 5 of FIG. 7 S510). Here, BTR _cur is calculated as shown in Equation (2).

&Quot; (2) "

BTR _cur = Channel usage time / (channel usage time + channel idle time)

The access point apparatus 200 calculates the BTR as shown in Equation (1) (S520).

The access point 200 compares the BTR _threshold calculated in step S520 with the BTR threshold (step S530).

The access point device 200 uses a power saving mode when the BTR is less than the BTR _threshold . Accordingly, the access point apparatus 200 sets the CFPCount field of the CF parameter set in the beacon frame to 0 in order to use the power saving mode in the next contention period (period 5) when the BTR is smaller than the BTR _threshold (S540).

The access point apparatus 200 sets the CFPCount field to a non-zero value when the BTR is equal to or greater than the BTR _threshold (S550).

The BTR will vary depending on the degree of use of the power saving mode even if the traffic in the BSS is constant. This is because, in the power saving mode, the frames of the terminal and the access point are buffered and transmitted in the next contention period, so that the channel use time in the next contention period can be increased.

Next, the configuration of the access point apparatus 200 and the operation procedure of the access point apparatus 200 will be described in detail with reference to Figs. 8 and 9. Fig.

8 is a configuration diagram schematically illustrating an access point apparatus for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention. 9 is a flowchart illustrating an operation procedure of an access point for power saving of a wireless device supporting a Wi-Fi tethering service according to an embodiment of the present invention.

8, the access point 200 includes a transmitting unit 210, a count value verifying unit 220, a timer setting unit 230, a buffering unit 240, a mode switching unit 250, 260 and a competitive period entry unit 270. [

The transmitting unit 210 transmits a beacon frame (S801).

The count value checking unit 220 checks the CFP counter value CFPCount included in the CFP parameter set of the beacon frame transmitted from the transmitting unit 210. [

Specifically, the count value check unit 220 determines whether the CFP counter value CFPCount corresponds to 0 (S802).

If the CFP counter value (CFPCount) does not correspond to 0, the count value checking unit 220 enters a contention period, and performs a DCF-based contention with other terminals to transmit a data frame.

If the CFP counter value CFPCount corresponds to zero, the timer setting unit 230 determines whether the PCF support terminal (CF-Pollable terminal) is within the set range (S803).

The timer setting unit 230 controls the PCF supporting terminal (CF-Pollable terminal) to perform the PCF operation when the PCF supporting terminal (CF-Pollable terminal) is within the setting range (S804). Next, the timer setting unit 230 sets a timer at the remaining time (T = CFPDurRemaining-t1-t2) (S805). In step S803, the timer setting unit 230 sets the timer to the remaining time (T = CFPDurRemaining-t1-t2) even when the PCF supporting terminal (CF-Pollable terminal) does not exist within the setting range. Here, t1 is a PCF operation execution time and t2 is a sifs + CF-END transfer time.

In step S804, after the PCF supporting terminal (CF-Pollable terminal) performs the PCF operation, the access point 200 sets the timer to the remaining time and enters the sleep mode. At this time, the access point apparatus 200 can save power during the T period of the sleep mode.

The buffering unit 240 sets a timer in the timer setting unit 230 and starts buffering (S806).

The mode switching unit 250 switches from the sleep mode to the active mode according to the confirmation result of the confirmation unit 260.

The confirmation unit 260 determines whether the terminal NS that has performed the power saving notification process as shown in FIG. 5 exists in the access point apparatus 200 (S807).

The confirmation unit 260 controls the mode switching unit 250 to maintain the sleep mode state until the timer expires if at least one terminal N _S exists. At this time, the terminal that has performed the power saving notification process will also enter the sleep mode based on the CFPDurRemaining value of the CF parameter set in the beacon frame. Therefore, if CF-End is sent before CFPDurRemaining, UEs in the sleep mode can not receive the CF-End, so that the UEs participate in the competition period late.

Therefore, the check unit 260 checks whether a terminal (N _S) In this case, 0 or more, in the sleep mode (S808), the timer expires in order to solve this problem (S809). At this time, the confirmation unit 260 must activate the sleep mode until the timer expires.

Further, the identification unit 260 is a terminal (N _S), the case of 0, the condition for switching to the active mode, in the sleep mode (S810) the timer expires if the check (S811) status terms of frames as well as buffers to (Operation S812).

First, the number of frames (N) to be buffered before the timer expires exceeds the frame threshold (N _threshold ). In this case, the number of frames (N) is the number of data frames to be transmitted to the remaining terminals except the data frame to be transmitted to the terminals entering the sleep mode by utilizing the power saving technique of the 802.11 standard.

Second, the delay time (D) of the first buffered data frame out of the buffered data frames exceeds the threshold (D _threshold ). In this case, D denotes the delay time of the first buffered data frame among the data frames excluding the data frame to be transmitted to the UEs entering the sleep mode using the power saving technique of the 802.11 standard.

If any one of the above two conditions is satisfied, the mode switching unit 250 switches to the active mode regardless of the timer (S813). This makes it possible to alleviate the delay problem that occurs when the sleep mode is lengthened.

The buffering unit 160 stops buffering after switching to the active mode as in step S813 (S814).

The contention period entering unit 270 broadcasts a CF-End frame (S815) and enters a contention period (S816). Herein, if there are terminals that have not received the beacon frame, the CF-End frame updates the NAV of these terminals to 0 so that all the terminals participate in the competition period at the same time.

The access point apparatus 200 increases the N _S value by one when the power saving notification process is performed as shown in FIG. 5 with the specific terminal, and reduces the value by 1 when the terminal is disconnected.

As described above, an optimal embodiment has been disclosed in the drawings and specification. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100; Terminal
110; A receiving unit 120; Setting confirmation unit
130; A process execution unit 140; Count value confirmation unit
150; A timer setting unit 160; The buffering unit
170; A mode switching unit 180; Competition Entry
200; Access point device
210; A transmission unit 220; Count value confirmation unit
230; A timer setting unit 240; The buffering unit
250; A mode switching unit 260; Confirmation unit
270; Competition Entry

Claims (19)

The access point device broadcasting a beacon frame;
Setting a timer according to a CFP counter value corresponding to the beacon frame;
Starting buffering and confirming whether a terminal performing the power saving notification process exists;
Checking the number of frames according to the timer or checking the number of buffered frames according to presence or absence of the terminal;
Switching the mode of the corresponding terminal from the sleep mode to the active mode regardless of the timer according to the result of the checking; And
Stopping the buffering after switching the mode of the terminal to the active mode, and entering the competition period
A method for power saving of a wireless device supporting a WiFi tethering service. The method according to claim 1,
The broadcasting step
And a B12 reserved bit in a capability information field of the beacon frame is set to 1 to broadcast the WiFi tethering service. The method according to claim 1,
The step of setting the timer
Checking the CFP counter value included in the CFP parameter set of the beacon frame;
Checking if the CF-Pollable terminal is within the set range if the CFP counter value is zero;
Controlling the CF-Pollable terminal to perform a PCF operation when the CF-Pollable terminal exists within a set range; And
The CF-Pollable terminal performs the PCF operation and sets the timer to the remaining time
A method for power saving of a wireless device supporting a WiFi tethering service. The method according to claim 1,
The power saving notification process
Receiving the power saving support notification frame from the access point device; And
The access point device generates a power saving support confirmation frame by using a confirmation message for the power saving support notification frame and transmits the power saving support confirmation frame to the corresponding terminal
The method comprising the steps of: (a) providing a Wi-Fi tethering service; The method according to claim 1,
Further comprising the step of determining whether the access point device uses the power save mode. ≪ Desc / Clms Page number 20 > The method of claim 5,
Wherein the step of determining whether to use the power saving mode
Determining a channel use level of a BBS that the access point is servicing with respect to a contention period before broadcasting the beacon frame;
Comparing the degree of channel use with a threshold value; And
And using the power saving mode when the channel usage level is less than a threshold value. ≪ Desc / Clms Page number 20 > The method according to claim 1,
The step of setting the timer
Confirming whether a PCF supporting terminal exists within a setting range when the CFP counter value corresponding to the beacon frame corresponds to zero;
Controlling the PCF supporting terminal to perform a PCF operation when the PCF supporting terminal exists; And
Setting a timer to a remaining time after the PCF supporting terminal performs a PCF operation, and entering a sleep mode. ≪ Desc / Clms Page number 20 > The method according to claim 1,
The switching step
If there is a terminal that has performed the power saving notification process, the number of frames buffered before the timer expires exceeds a frame threshold,
And when the delay time of the first buffered frame exceeds a threshold value, the active mode is switched to the active mode. The method according to claim 1,
The switching step
When the number of frames to be buffered before the timer expires exceeds a frame threshold value in the absence of the terminal performing the power saving notification process, the active mode is switched to the active mode. A METHOD FOR SAVING POWER OF A RADIO DEVICE. Receiving a beacon frame broadcasted by an access point device;
Determining whether a power saving notification process has been performed with the access point apparatus when a power saving bit is set in the beacon frame;
Confirming a CFP counter value corresponding to the beacon frame when the power saving notification process is performed;
Setting a timer according to the CFP counter value and starting buffering of the beacon frame;
Switching from an active mode to a sleep mode when the buffering starts and switching from the sleep mode to the active mode when the timer expires; And
Stop buffering of the beacon frame, start transmission of the buffered beacon frame according to the DCF operation procedure, and enter a competition period
A method for power saving of a wireless device supporting a WiFi tethering service. The method of claim 10,
Prior to determining whether the power saving notification process has been performed,
Wherein the power saving bit is set through a probe response or an association response frame in addition to the beacon frame. The method of claim 10,
The power saving notification process
Connecting the terminal to the access point device;
The terminal generates a power saving support notification frame and transmits the power saving support notification frame to the access point to notify participation in a power saving operation; And
Receiving a power saving support confirmation frame corresponding to the power saving support notification frame from the access point apparatus
The method comprising the steps of: (a) providing a Wi-Fi tethering service; The method of claim 10,
If the CFP counter value does not correspond to zero, entering a contention period and transmitting the beacon frame to the access point device according to a DCF operation procedure. A method for power saving of a device. The method of claim 10,
The step of initiating the buffering
Setting a network location vector value using the CFPDurRemaining value if the CFP counter value is zero and checking whether the terminal itself corresponds to a PCF supporting terminal; And
And setting the timer according to a result of checking whether the terminal corresponds to the PCF supporting terminal. A transmitting unit for broadcasting a beacon frame;
A timer setting unit for setting a timer according to a CFP counter value corresponding to the beacon frame;
A buffering unit for buffering the beacon frame;
A confirmation unit for checking whether there is a terminal that has performed the power saving notification process, checking the number of beacon frames according to the timer according to the presence or absence of the terminal, or checking the number of buffered beacon frames;
A mode switching unit for switching the mode of the corresponding terminal from the sleep mode to the active mode regardless of the timer according to the result of the check; And
The buffering is stopped after the mode of the corresponding terminal is switched to the active mode,
The access point device for power saving of wireless devices supporting Wi-Fi tethering service. 16. The method of claim 15,
The transmitter
And the B12 reserved bit in the capability information field of the beacon frame is set to 1 to broadcast the WiFi tethering service. 16. The method of claim 15,
The timer setting unit
When the CFP counter value included in the CFP parameter set of the beacon frame corresponds to zero and the CF-Pollable terminal exists within the setting range, the CF-Pollable terminal controls the PCF operation to perform the PCF operation, And the timer is set to the remaining time after the pollable terminal performs the PCF operation. The access point device for power saving of the wireless device supporting the WiFi tethering service. 16. The method of claim 15,
The mode switching unit
If there is a terminal that has performed the power saving notification process, if the number of frames buffered before the timer expires exceeds a frame threshold and the delay time of the first buffered frame exceeds the threshold value The access point is switched to the active mode. 16. The method of claim 15,
The mode switching unit
When the number of frames to be buffered before the timer expires exceeds a frame threshold value in the absence of the terminal performing the power saving notification process, the active mode is switched to the active mode. Access point device for power saving of wireless device.

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