WO2014077598A1

WO2014077598A1 - Access point device for saving power of wireless device supporting wi-fi tethering service, and method therefor

Info

Publication number: WO2014077598A1
Application number: PCT/KR2013/010335
Authority: WO
Inventors: 김동욱; 김신규; 서정택
Original assignee: 한국전자통신연구원
Priority date: 2012-11-16
Filing date: 2013-11-14
Publication date: 2014-05-22

Abstract

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

Description

Access point device and method for reducing power of wireless device supporting Wi-Fi tethering service

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

The present invention claims the benefit of the date of application of Korean Patent Application No. 10-2012-0130132, filed November 16, 2012 and Korean Patent Application No. 10-2013-0122815, filed October 15, 2013, the contents of all Is included herein.

WiFi tethering is a feature that is widely supported in commercial smartphones recently, and mobile devices that can connect to the Internet through 3G / 4G, etc., provide Internet services using WiFi to other devices that cannot use the Internet service. Giving is a skill.

Such a mobile terminal supporting WiFi tethering is referred to as a mobile software access point (MSAP).

1 illustrates an example of WiFi tethering in which two terminals STA1 and STA2 receive an Internet service through a terminal STA 3 corresponding to a mobile software access point MSAP. Here, the mobile software access point (MSAP) may 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 WLAN is a standard technology of IEEE that has long been widely used by many wireless communication users. In WLAN, there are two modes, an infrastructure mode and an ad hoc 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. In contrast, in the ad hoc mode, direct communication between two terminals is possible.

The medium access method of the 802.11-based WLAN is classified into a distributed coordination function (DCF) and a point coordination function (PCF).

DCF based on Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) is a medium access method used during a contention period (CP). UEs using DCF are connected to other UEs before transmitting their frames. Contention with the client. 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 allocates data frames according to its turn. It's a way of delivering.

Next, an operation process of obtaining a channel necessary for the access point to perform the PCF will be described.

First, the access point must control other terminals not to attempt to access the channel while the PCF operation is in progress, and thus can successfully perform the operation of the PCF. To this end, the access point and the terminal in the standard operates as follows.

If the access point supports the PCF mode, the beacon frame broadcast by the access point includes a CFP parameter set (Content Free Parameter Set).

The CFP parameter set consists of four fields (CFPCount, CFPPeriod, CFPMaxDuration, and CFPDurRemaining). Among these, CFPMaxDuration and CFPDurRemaining are fields that specify time to use as non-competition period. CFPMaxDuration represents the maximum allowable value of non-competition period and CFPDurRemaining represents the value of non-competition period currently set in beacon frame. And CFPCount means the number of beacon frames to be transmitted until the next non-competition period. That is, when CFPCount is 0, it means that the non-competition period starts immediately after sending the beacon frame. When the non-competition period is scheduled, that is, when the CFPCount of the beacon frame to be received is 0, the UE sets its NAV (Network Allocation Vector) to the CFPMaxDuration value. The terminal obtains the CFPMaxDuration value through the previously received beacon frame or probe response frame. Since the CFPCount value decreases by 1 for each beacon frame, the CFPCount can be predicted even when the beacon frame is not received, and thus, the non-competition period is scheduled. If the beacon frame is successfully received during this period and the CFPCount value is 0, the UE resets its NAV using the CFPDurRemaining value of the CF parameter set. In the 802.11 standard, since the terminal will not attempt to transmit on the channel until the NAV expires, the access point may acquire the channel during CFPDurRemaining. This period is called a non-competition period, and the access point performs data exchange through polling sequentially with terminals (CF-Pollable terminals) supporting the PCF during this period. After completing the polling process, the access point signals the end of the PCF operation by broadcasting a CF-End frame. UEs receiving the CF-End frame set their NAV to 0 and enter a contention period. The terminals may now participate in data frame transmission according to the operation of the DCF.

Next, a power saving mode is to reduce power of a terminal wasted during idle time when a channel is not used, and belongs to the IEEE 802.11 standard technology. A terminal supporting the power saving scheme utilizes two modes, an active mode and a sleep mode. The terminal in the active mode refers to a state in which the wireless interface is turned on to enable data communication with an access point (infrastructure mode) or another terminal (ad hoc mode). On the other hand, the terminal in the sleep mode refers to a state in which the wireless interface is turned off to reduce power consumption, and consumes low power rather than the state in which the wireless interface is turned on. The terminal supporting the power saving scheme may switch to the sleep mode due to less or different data exchanged with the access point or another terminal. Prior to switching to the sleep mode, the UE notifies the access point of switching to the sleep mode and receives a response message. An access point that is aware of a particular terminal switching to sleep mode starts buffering data frames destined for the terminal. The terminal in the sleep mode state periodically switches to the active mode (for example, beacon period), checks the beacon frame and determines whether there is data to be received from the access point. In the beacon frame, there is a TIM (Traffic Indication Map) field, and each bit of the corresponding field is mapped one-to-one with terminals currently connected. The access point sets the corresponding bit of the TIM field to 1 when one or more data frames for a specific terminal are buffered. If there is a data frame to be received by the terminal, it transmits a PS_Poll management frame to the access point to inform that it 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, the access point sets the MD (more data) bit of the frame control field in the MAC header of the data frame to 1 when there are more data frames destined for the terminal. If the MD bit is set to 1, the terminal retransmits 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 that the access point sends to that terminal is set to 0), the terminal sends the PM bit of the frame control field in the ACK frame to 1 in response to the last data frame. Set to to send to the access point and go back to sleep mode. In this manner, since the terminal switches to the active mode and receives data only when there is a data frame to be received, the terminal can reduce power consumption of the terminal.

However, the IEEE 802.11 standard states that access points are not allowed to enter sleep mode using power saving techniques. This is because in the conventional access point, since the main power is always used, the reduction of power consumption is not a big issue. However, with the advent of battery-powered portable devices and their support for Mobile Software Access Point (MSAP) features, access points also need to reduce power consumption. However, there is a limitation in applying a power saving technique for a terminal described in the IEEE standard to a mobile software access point. The reason is that the current power saving technique does not have an operation procedure for notifying the terminal of the access point to enter the sleep mode. If the access point enters the sleep mode without the sleep mode entry notification process to the terminal, the terminal does not know this problem occurs that there is a loss of uplink data frames transmitted by the terminal to the access point.

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

Method for reducing power of a wireless device supporting the Wi-Fi tethering service according to the present invention for achieving the above object

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 checking whether there is a terminal that has performed a power saving notification process; Checking the number of frames according to the timer or the number of buffered frames according to the presence of the terminal; Switching a mode of a corresponding terminal from a sleep mode to an active mode regardless of the timer according to the check result; And stopping the buffering after entering the active mode of the terminal and entering a contention period.

In this case, the broadcasting may include broadcasting by setting B12 reserved bit to 1 in the capability information field of the beacon frame.

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; Checking whether a CF-Pollable terminal exists within a setting range when the CFP counter value corresponds to zero: when the CF-Pollable terminal exists within a setting range, the CF-Pollable terminal performs a PCF operation Controlling; And setting the timer to the time remaining after the CF-Pollable terminal performs the PCF operation.

At this time, the power saving notification process, the access point device receives a power saving support notification frame from the terminal; And generating, by the access point device, a power saving support confirmation frame as a confirmation message for the power saving support notification frame, and transmitting the generated power saving support confirmation frame to the corresponding terminal.

At this time, the access point device further comprises the step of determining whether to use the power saving mode.

At this time, the step of determining whether to use the power saving mode comprises the steps of determining the channel usage of the BBS that is serving its own for the contention period before the access point device broadcasts the beacon frame; Comparing the channel usage with a threshold; And using the power saving mode when the channel usage degree is less than a threshold.

In this case, the setting of the timer may include checking whether the PCF supporting terminal is within a setting range when the CFP counter value corresponding to the beacon frame corresponds to zero; If the PCF supporting terminal exists, controlling the PCF supporting terminal to perform a PCF operation; And setting a timer as a time remaining after the PCF supporting terminal performs the PCF operation, and entering a sleep mode.

At this time, 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, the first of the buffered frame of the buffered frame When the delay time exceeds the threshold, it is characterized by switching to the active mode.

In this case, the switching may include switching to the active mode when the number of frames buffered before the timer expires exceeds a frame threshold when the terminal that has performed the power saving notification process does not exist. It is done.

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

Receiving, by the terminal, a beacon frame broadcast by the access point device; If a power saving bit is set in the beacon frame, determining whether a power saving notification process has been performed with the access point apparatus; Checking 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 the active mode to the sleep mode when the buffering starts, and switching from the sleep mode to the active mode when the timer expires; And stopping buffering of the beacon frame and starting transmission of the buffered beacon frame according to a DCF operation to enter a contention period.

At this time, before the step of determining whether the power saving notification process is performed, it is characterized in that whether the power saving bit is set through a probe response or an associated response frame in addition to the beacon frame.

At this time, the power saving notification process is the step of connecting the terminal to the access point device; Generating, by the terminal, a power saving support notification frame and transmitting the generated power saving support notification frame to the access point to indicate that the terminal participates 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 device.

In this case, if the CFP counter value does not correspond to zero, the method further includes entering a contention period and transmitting the beacon frame to the access point device according to a DCF operation process.

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

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

A transmission unit 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 configured to perform buffering on the beacon frame; A confirmation unit for confirming whether there is a terminal that has performed a power saving notification process and checking the number of beacon frames according to the timer according to the presence of the terminal, or confirming the number of buffered beacon frames; A mode switching unit for switching a mode of a corresponding terminal from a sleep mode to an active mode regardless of the timer according to the checking result; And a contention period entry unit for stopping buffering and entering a contention period after switching the mode of the terminal to the active mode.

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

In this case, 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 a setting range, the CF-Pollable terminal performs a PCF operation. By controlling so as to, the CF-Pollable terminal is characterized by setting the timer to the time remaining after performing the PCF operation.

In this case, when there is a terminal that performs the power saving notification process, the mode switching unit exceeds a frame threshold when the number of frames buffered before the timer expires, and delays the first buffered frame among the buffered frames. If the time exceeds the threshold, it is characterized by switching to the active mode.

In this case, when there is no terminal that performs the power saving notification process, the mode switching unit switches to the active mode when the number of frames buffered before the timer expires exceeds a frame threshold. do.

The present invention can realize the Wi-Fi interface power consumption reduction of the access point device through the modification of the access point device without requiring the modification of the terminal. In addition, when the terminal is modified to recognize the power consumption reduction operation process for the access point device, it is possible to reduce the power consumption for the same period.

FIG. 1 is a diagram illustrating an example of WiFi tethering in which two terminals receive an 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.

4 is a flowchart illustrating an operation process 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 view showing a power saving notification process according to an embodiment of the present invention.

6 is a flowchart illustrating a process periodically performed by an access point apparatus according to an embodiment of the present invention to determine whether to use a power saving technique.

7 is a diagram illustrating a competition period and a non-competition period for each period according to an embodiment of the present invention.

8 is a block diagram schematically illustrating 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.

9 is a flowchart illustrating an operation of 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.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Here, the repeated description, well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention, and detailed description of the configuration will be omitted. Embodiments of the present invention are provided to more completely describe the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity.

Hereinafter, a terminal, an access point apparatus, and a method for reducing power 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 process of obtaining a channel necessary to perform a conventional PCF using a CFP parameter set (Content Free Parameter Set) of the beacon frame. The access point device, which has obtained the channel in the standard, exchanges data frames through polling sequentially with terminals supporting each PCF, and then directly transmits a CF-End frame to enter a contention period. However, in the present invention, the access point device obtained the channel sequentially exchanges data frames through polling with terminals supporting each PCF, and then transmits a CF-End frame just before CFPDurRemaining expires. Using this method, the access point device may 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 downlink data frames. As long as the terminal can recognize the use of the power saving scheme by the access point apparatus, power can be saved for the same time period in the corresponding terminal. Similarly, during this period, the UE buffers uplink data frames.

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

The access point apparatus 200 supporting the power saving mode may broadcast the B12 reserved bit in the capability information field of the beacon frame to 1 to broadcast the power saving operation. Here, setting the B12 reserved bit to 1 means that the access point device 200 supports an operation process for reducing its own power.

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

Next, a configuration of the terminal 100 and an operation process of the terminal 100 will be described in detail with reference to FIGS. 2 and 3.

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 process 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 view showing a power saving notification process according to an embodiment of the present invention.

Referring to FIG. 3, the terminal 100 includes a receiving unit 110, a setting confirming unit 120, a process performing unit 130, a count value checking unit 140, a timer setting unit 150, and a buffering unit 160. , Mode switching unit 170 and competition period entry unit 180.

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

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

When 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 performing unit 130 does not perform the power saving notification process with the access point apparatus 200, the process performing unit 130 performs the power saving notification process (S304).

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

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

The terminal 100 generates a power saving support notification frame and transmits the generated power saving support notification frame to the access point apparatus 200 (S420), indicating that the terminal 100 participates 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 as a confirmation message for the power saving support notification frame and transmits the generated 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 receiving the power saving support confirmation frame may reduce power consumption by entering the sleep mode according to the time when the access point device performs power saving.

When the beacon frame is received (S301), the AP power saving bit is set to 1 in the beacon frame (S302) and the count value check unit 140 when the power saving notification process is performed with the corresponding access point device. Checks the CFP counter value (CFPCount) of the CFP parameter set (Content Free Parameter Set) in the beacon frame.

In detail, the count value checking unit 140 determines whether the CFP counter value CFPCount corresponds to 0 (S305).

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

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

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

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

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

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

When the buffering of the frame starts, 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), and switches back to the active mode when the timer expires (S313).

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

The contention period entry unit 180 enters a contention period by starting buffered frame transmission according to the DCF operation (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. In other words, it is noted that this operation of the terminal 100 is performed separately from the power saving mode of the terminal described in the IEEE 802.11 standard. In addition, the terminal that does not recognize that the access point apparatus 200 performs the power saving operation, that is, the unmodified terminal will not check the AP power saving bit of the beacon frame.

Next, a process of periodically performing the access point apparatus 200 to determine whether to use the power saving method will be described in detail with reference to FIG. 6.

6 is a flowchart illustrating a process periodically performed by an access point apparatus according to an embodiment of the present invention to determine whether to use a power saving technique. 7 is a diagram illustrating a competition period and a non-competition period for each period according to an embodiment of the present invention.

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

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

However, when the access point device decides to use the power saving mode, as in periods 2 and 3 of FIG. 7, a part of the entire period is used as a non-competitive basis for the power saving mode, and the rest is used as a competition period for data exchange. do.

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

For example, in FIG. 7, the access point device 200 calculates the busy time ratio (BTR) of the BSS that it is serving for the contention period before transmitting the beacon frame (T1) after period 4 to use the channel. Judge the degree. Here, BTR is calculated as in Equation 1.

[Equation 1]

BTR = BRTnew = α * BTRcur + (1-α) * BTR _old

In Equation 1, α 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 a measure of the ratio of time the channel is used to transmit a frame in the measurement period.

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

Equation 2 BTR _cur = channel usage time / (channel usage time + channel idle time)

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

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

The access point apparatus 200 uses the power saving mode when the BTR is smaller 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 to use the power saving mode in the next contention period (period 5) when the BTR is less than the BTR _threshold . (S540).

Access point apparatus 200 is set, the BTR field CFPCount to not less than the threshold BTR (BTR _threshold) to a value other than zero (S550).

The BTR will change depending on the degree of use of the power saving mode even if the traffic in the BSS is constant. This is because the frames of the terminal and the access point apparatus are buffered and transmitted in the next contention period in the power saving mode, thereby increasing the channel usage time in the next contention period.

Next, a configuration of the access point apparatus 200 and an operation process of the access point apparatus 200 will be described in detail with reference to FIGS. 8 and 9.

8 is a block diagram schematically illustrating 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. 9 is a flowchart illustrating an operation process of 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.

Referring to FIG. 8, the access point apparatus 200 may include a transmitter 210, a count value checker 220, a timer setting unit 230, a buffering unit 240, a mode switching unit 250, and a checker ( 260 and a competition entry 270.

The transmitter 210 transmits a beacon frame (S801).

The count value checker 220 checks the CFP counter value (CFPCount) included in the CFP parameter set of the beacon frame transmitted by the transmitter 210.

In detail, the count value checking unit 220 determines whether the CFP counter value CFPCount corresponds to 0 (S802).

When 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.

When the CFP counter value CFPCount corresponds to zero, the timer setting unit 230 checks whether a PCF support terminal (CF-Pollable terminal) exists within a setting range (S803).

The timer setting unit 230 controls the PCF support terminal (CF-Pollable terminal) to perform the PCF operation when the PCF support terminal (CF-Pollable terminal) exists within the setting range (S804). Next, the timer setting unit 230 sets the timer to the remaining time (T = CFPDurRemaining-t1-t2) (S805). In addition, 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 in step S803. Here, t1 is the execution time of the PCF operation, t2 is the sifs + CF-END transmission time.

In operation S804, the access point apparatus 200 sets a timer for the remaining time after the PCF support terminal (CF-Pollable terminal) performs the PCF operation, and enters the sleep mode. In this case, the access point apparatus 200 may save power during the T period in 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 check result of the check unit 260.

The verification unit 260 checks whether the terminal NS which performed the power saving notification process as shown in FIG. 5 exists in the access point apparatus 200 (S807).

When one or more terminals N _S exist, the identification unit 260 controls the mode switching unit 250 to maintain the sleep mode until the timer expires. At this time, the terminal that 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 the CF-End is sent before CFPDurRemaining, the terminals in the sleep mode cannot receive the CF-End, and thus, the terminals participate in a late competition period.

Therefore, in order to solve such a problem, the checking unit 260 checks whether the timer expires in the sleep mode (S808) when the terminal N _S is 0 or more (S809). At this time, the verification unit 260 should retain the sleep mode until the timer expires.

In addition, when the terminal N _S is 0, the checking unit 260 is a condition for switching to the active mode, and in the sleep mode (S810), not only checks whether the timer expires (S811), but also status conditions of the buffered frames. In operation S812, the process of determining the operation is additionally performed.

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

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

If any one of the two conditions described above is satisfied, the mode switching unit 250 switches to the active mode regardless of the timer (S813). This can alleviate the delay that occurs when the sleep mode gets longer.

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

The competition period entry unit 270 broadcasts the CF-End frame (S815) and then enters a competition period (S816). Here, when there are terminals that do not receive the beacon frame, the CF-End frame updates the NAV of these terminals to 0 so that all terminals participate in the contention period at the same time.

The access point apparatus 200 increases the N _S value by 1 when the specific terminal performs the power saving notification process as shown in FIG. 5, and decreases the value by 1 when the terminal disconnects.

As described above, the best embodiment has been disclosed in the drawings and the specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims

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 checking whether there is a terminal that has performed a power saving notification process;

Checking the number of frames according to the timer or the number of buffered frames according to the presence of the terminal;

Switching a mode of a corresponding terminal from a sleep mode to an active mode regardless of the timer according to the check result; And

Stopping the buffering after entering the active mode and entering a contention period

Method for power saving of a wireless device supporting a Wi-Fi tethering service comprising a.
The method according to claim 1,

The broadcasting step

And setting the B12 reserved bit in the capability information field of the beacon frame to 1 to broadcast the power savings of the wireless device supporting the Wi-Fi tethering service.
The method according to claim 1,

Setting the timer

Checking the CFP counter value included in the CFP parameter set of the beacon frame;

If the CFP counter value corresponds to zero, checking whether the CF-Pollable terminal exists within a setting range:

If the CF-Pollable terminal exists within a setting range, controlling the CF-Pollable terminal to perform a PCF operation; And

Setting the timer to the time remaining after the CF-Pollable terminal performs the PCF operation

Method for power saving of a wireless device supporting a Wi-Fi tethering service comprising a.
The method according to claim 1,

The power saving notification process

Receiving, by the access point device, a power saving support notification frame from the terminal; And

Generating, by the access point device, a power saving support confirmation frame as a confirmation message for the power saving support notification frame, and transmitting the generated power saving support confirmation frame to a corresponding terminal; Way for you.
The method according to claim 1,

And determining, by the access point device, whether to use a power saving mode or not. The method for power saving of a wireless device supporting a WiFi tethering service.
The method according to claim 5,

Determining whether to use the power saving mode is

Determining, by the access point device, the channel usage degree of the BBS serviced by the BBS for the contention period before broadcasting the beacon frame;

Comparing the channel usage with a threshold; And

And using the power saving mode when the channel use degree is less than a threshold.
The method according to claim 1,

Setting the timer

When the CFP counter value corresponding to the beacon frame corresponds to zero, checking whether the PCF supporting terminal is within a setting range;

If the PCF supporting terminal exists, controlling the PCF supporting terminal to perform a PCF operation; And

And setting a timer as a time remaining after the PCF supporting terminal performs a PCF operation, and entering a sleep mode.
The method according to claim 1,

The converting step

When there is a terminal that performs the power saving notification processor, when the number of frames buffered before the timer expires exceeds a frame threshold and the delay time of the first buffered frame among the buffered frames exceeds the threshold. The method for reducing power of a wireless device supporting a Wi-Fi tethering service, characterized in that for switching to the active mode.
The method according to claim 1,

The converting step

When there is no terminal that performs the power saving notification process, when the number of frames buffered before the timer expires exceeds the frame threshold, the Wi-Fi tethering service is supported. A method for reducing power of a wireless device.
Receiving, by the terminal, a beacon frame broadcast by the access point device;

If a power saving bit is set in the beacon frame, determining whether a power saving notification process has been performed with the access point apparatus;

Checking 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 the active mode to the sleep mode when the buffering starts, and switching from the sleep mode to the active mode when the timer expires; And

Stopping buffering of the beacon frame and starting transmission of a buffered beacon frame according to a DCF operation to enter a contention period

Method for power saving of a wireless device supporting a Wi-Fi tethering service comprising a.
The method according to claim 10,

Before the step of determining whether the power saving notification process has been performed, the wireless device supporting the Wi-Fi tethering service characterized by checking whether the power saving bit is set through a probe response or an associated response frame in addition to the beacon frame. How to save power.
The method according to claim 10,

The power saving notification process

Connecting the terminal to the access point apparatus;

Generating, by the terminal, a power saving support notification frame and transmitting the generated power saving support notification frame to the access point to indicate that the terminal participates 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 device;

Method for reducing power of a wireless device supporting a Wi-Fi tethering service comprising a.
The method according to 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 process; How to save power in your device.
The method according to claim 10,

Starting the buffering

If the CFP counter value corresponds to zero, setting a network location vector value using a CFPDurRemaining value and confirming whether the terminal corresponds to a PCF supporting terminal; And

And setting the timer according to a result of checking whether the PCF support terminal corresponds to the PCF supporting terminal.
A transmission unit 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 configured to perform buffering on the beacon frame;

A confirmation unit for confirming whether there is a terminal that has performed a power saving notification process and checking the number of beacon frames according to the timer according to the presence of the terminal, or confirming the number of buffered beacon frames;

A mode switching unit for switching a mode of a corresponding terminal from a sleep mode to an active mode regardless of the timer according to the checking result; And

Competition period entry unit which stops buffering and enters a competition period after changing the mode of the terminal to an active mode

Access point device for power saving of a wireless device that supports a Wi-Fi tethering service comprising a.
The method according to claim 15,

The transmission unit

And a B12 reserved bit in the capability information field of the beacon frame to be set to 1 to broadcast power to a wireless device supporting the Wi-Fi tethering service.
The method according to claim 15,

The timer setting unit

If the CFP counter value included in the CFP parameter set of the beacon frame corresponds to zero, and the CF-Pollable terminal exists within a setting range, the CF-Pollable terminal is controlled to perform a PCF operation, so that the CF- Access point device for power saving of a wireless device supporting a Wi-Fi tethering service, characterized in that for setting the timer to the time remaining after the pollable terminal performs the PCF operation.
The method according to claim 15,

The mode switching unit

When there is a terminal that performs the power saving notification process, when the number of frames buffered before the timer expires exceeds a frame threshold, and the delay time of the first buffered frame among the buffered frames exceeds the threshold. To, the access point device for power saving of the wireless device supporting the Wi-Fi tethering service, characterized in that for switching to the active mode.
The method according to claim 15,

The mode switching unit

When there is no terminal that performs the power saving notification process, when the number of frames buffered before the timer expires exceeds the frame threshold, the Wi-Fi tethering service is supported. Access point device for power saving of the wireless device.