WO2013187706A1

WO2013187706A1 - Apparatus and method for controlling transmission schedule for buffered data in wireless lan, and terminal for receiving buffered data based on transmission schedule in wireless lan

Info

Publication number: WO2013187706A1
Application number: PCT/KR2013/005223
Authority: WO
Inventors: 권형진; 이재승; 정민호; 유희정; 이석규
Original assignee: 한국전자통신연구원
Priority date: 2012-06-13
Filing date: 2013-06-13
Publication date: 2013-12-19

Abstract

The present invention relates to a technology for controlling a transmission schedule for buffered data, which involves an access point that manages a network acquiring information on the transmission schedule from a terminal in a wireless local area network (WLAN) environment. The apparatus for controlling a transmission schedule for buffered data in a wireless LAN according to one embodiment of the invention groups terminals together on the basis of the service characteristics and/or traffic characteristics of the terminals, allocates group information to the groups such that the groups of terminals can wake up at different times, and transmits group delivery traffic indication map (DTIM) information and/or buffered data based on the allocated group information.

Description

Apparatus and method for controlling a transmission schedule of data buffered in a WLAN, a terminal for receiving data buffered based on a transmission schedule in a WLAN

Examples described below relate to a technique of controlling a schedule for transmitting data buffered by an access point managing a network to a terminal in a wireless local area network (WLAN) environment, and obtaining the scheduling information at the terminal.

In a power save mode of a WLAN environment, an access point (AP) periodically displays information indicating the existence of a buffered frame for each terminal when a frame to be transmitted to STAs is buffered. Reflect on (TIM), can be inserted into the beacon and transmitted. The TIM consists of a bitmap, one bit of the TIM corresponds to one STA, and corresponds to an association identifier (AID) mapped to the STA.

If there is a buffered frame to be transmitted to each STA, the AP may transmit by setting a bit corresponding to the STA to which the buffered frame is to be transmitted in the TIM to 1. The STA, in power up mode, must wake up to check the beacon's TIM.

If it is confirmed that there is a buffered frame from the TIM, the STA transmits a PS-POLL frame or a trigger frame to obtain the buffered frame. However, if the number of buffered frames is large, a collision occurs because many STAs access the channel for a short period of time.

For example, the TIM may be configured with 2008 bits to indicate the presence of buffered frames for up to 2007 STAs. The number of bits set to 1 in the TIM may be hundreds, and additionally, 6000 or more STAs may be associated with the AP in consideration of the sensor node.

Accordingly, there is a need for a technique for minimizing the collision among many STAs in the channel access process and minimizing the power consumed by the STAs.

In order to prevent a large number of STAs from accessing a channel in a short time period, the STAs are grouped, and a unit in which a STA belonging to a group wakes up varies its period from group to group according to characteristics of various services or traffic; To provide a method.

In addition, when a group including STAs having the same period is large, a group is divided into a plurality of subgroups, and a STA belonging to each subgroup can know transmission of DTIM based on information on period and offset. To provide.

An apparatus for scheduling transmission of data buffered in a WLAN according to an embodiment includes a grouping unit for grouping the terminals based on at least one of service characteristics and traffic characteristics of terminals, and group information to wake up at different times for each of the grouped groups. And a transmitter for transmitting at least one of group delivery traffic indication map (DTIM) information and buffered data based on the allocated group information.

The grouping unit may group terminals on the basis of an association identifier (AID) associated with a traffic indication map (TIM) indicating whether a frame is buffered at an access point.

The grouping unit may group the terminals included in the grouped group into subgroups including a predetermined number or less.

The group information allocator is configured to determine a transmission period of a group DTIM representing a presence of buffered data corresponding to a terminal belonging to the grouped group, differently between the groups, and a group identifier for identifying the grouped group. By generating an identifier generator to generate a count value in conjunction with the group DTIM transmission period determined by the transmission period determination unit, by setting an offset value to the group counter indicating the transmission time of the group DTIM and a subgroup of the grouped group It may include an offset counter indicating the transmission time of the group DTIM of the subgroup.

The group information may include a transmission period of the group DTIM, the group identifier, a counter ID (ID, identifier) of the group counter, a current count value, and an offset value of an offset counter.

The count value of the group counter may be determined based on the transmission period of the group DTIM.

The offset value of the offset counter may be determined based on the transmission period of the beacon transmitted by the transmitter.

The transmitter may transmit the group information allocated by the group information allocator to the grouped groups.

After the group information is assigned to the group, the transmitter may transmit the group DTIM information by inserting a group DTIM descriptor element updated at every transmission time into a beacon.

The group DTIM descriptor element includes a count value decremented by 1 for each transmission period of the group DTIM, and an offset value that increases by 1 for each transmission period of the beacon when the count value becomes 0, and the transmission unit includes the count value. When the value is 0, the group DTIM information of the group having the offset value of 0 is transmitted, and if the offset value is increased for each transmission period of the beacon after the count value becomes 0, the transmission value is increased to the increased offset value. Group DTIM information of a corresponding group may be transmitted.

A terminal for receiving data buffered in a WLAN according to an embodiment receives a beacon including group information and a group DTIM descriptor element from an access point, and a transmission period of the group information and the beacon Comparing the group DTIM descriptor element updated for each time, a calculation unit for calculating the transmission time of the Group Delivery Traffic Indication Map (DTIM) of the group to which the terminal belongs and wakes up based on the calculated transmission time, and the access point It includes a request unit for requesting data buffered by.

The group information may include a transmission period of the group DTIM, a group identifier, a counter ID (ID, Identifier) and a current count value of a group counter, and an offset value of an offset counter.

The group DTIM descriptor element may include a count value that decreases by one for each transmission period of the group DTIM, and an offset value that increases by one for each transmission period of the beacon when the count value becomes zero.

The calculating unit may include an identification unit identifying a group to which the terminal belongs, a transmission period of the group DTIM, a count value of the group DTIM descriptor element, an offset value of the offset counter, and the like. And a estimator for comparing the offset values of the group DTIM descriptor elements and an estimator for estimating the transmission time of the group DTIM based on the comparison result.

The terminal receiving the buffered data in the WLAN according to another embodiment may further include a transmission unit for transmitting at least one of the service characteristics and traffic characteristics of the terminal to the access point.

The transmitter transmits a PS-Poll (Power Save Poll) frame or a trigger frame requesting the buffered data to the access point, and the receiver receives the buffered data in response to the PS-Poll frame or the trigger frame. can do.

According to an embodiment of the present disclosure, a method of scheduling a buffered data transmission in a WLAN includes grouping the terminals based on at least one of a service characteristic and a traffic characteristic of the terminals, and group information to wake up at different times for each grouped group. And transmitting at least one of group delivery traffic indication map (DTIM) information and buffered data based on the allocating and the allocated group information.

The grouping may include grouping the terminals included in the grouped group into subgroups having a predetermined number or less.

The allocating step may include differently determining a transmission period of a group DTIM representing a presence of buffered data corresponding to a terminal belonging to the grouped group between the groups, and generating a group identifier for identifying the grouped group. Informing the transmission time of the group DTIM by setting a count value of a group counter in conjunction with the determined group DTIM transmission period, and setting an offset value of an offset counter in a subgroup of the grouped group. It may include the step of notifying the transmission time of the DTIM.

The transmitting may include transmitting the allocated group information to the grouped groups.

In accordance with an embodiment, an apparatus for controlling transmission schedule of data buffered in a WLAN is performed by grouping STAs and providing information on a transmission cycle of DTIM at different periods or at different periods and offsets for each group. It can wake up at different times to obtain the buffered data. In addition, the collision occurring in the process of channel access is thereby reduced, so that power saving of the STA and overall network performance can be improved.

In addition, since the terminal according to an embodiment can find out the DTIM transmission schedule of the group to which the STA belongs, even if any beacons other than the DTIM transmission period of the STA, even if an error occurs in the DTIM transmission schedule to which the STA belongs, restore again This is possible.

1 illustrates a WLAN environment including an access point and a plurality of terminals to which an embodiment of the present invention can be applied.

2 is a block diagram of an apparatus for controlling a transmission schedule of data buffered in a WLAN according to an embodiment of the present invention.

3 is a block diagram of a terminal for receiving data buffered based on a transmission schedule in a WLAN according to an embodiment of the present invention.

4 is a flowchart illustrating a method for controlling a transmission schedule of buffered data in a WLAN according to an embodiment of the present invention.

5 is a flowchart illustrating a method of controlling a transmission schedule of data buffered in a WLAN according to another embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, the access point (AP) 110 transmits a TIM indicating the presence of data buffered to the terminals STA1, STA2, STA3, STA4, STA5, STA6, STA7, STA8, and STA9 in group units. Can be.

In the infrastructure mode of the WLAN, the AP 110 may buffer a frame for terminals STA1, STA2, STA3, STA4, STA5, STA6, STA7, STA8, and STA9 in the low power mode. .

The AP 110 may receive information on service characteristics or traffic characteristics of the terminals from the terminals STA1, STA2, STA3, STA4, STA5, STA6, STA7, STA8, and STA9, respectively.

The information on the traffic characteristic may be TCLAS (Traffic Class) information used in IEEE 802.11e, and the information on the service characteristic may be access category (AC) information of EDCA (Enhanced Distributed Channel Access). Alternatively, information on service characteristics or traffic characteristics may be newly defined according to an application.

Information on service characteristics or traffic characteristics may be included in an associated information element (IE) or field defined in the specification and transmitted. A new group DTIM request element format may be defined, and information on a service characteristic or a traffic characteristic may be defined and transmitted as a sub-element therein. In addition, a new group DTIM request frame is defined, and information on service characteristics or traffic characteristics may be defined and transmitted as an element therein. In addition, it may be inserted as an element of an association request frame or a re-association request frame and transmitted when the association or reassociation is performed.

In addition, the traffic period may be included as the traffic characteristic information. The traffic period may be included in a group DTIM delivery interval field in a group DTIM request element format.

The AP 110 may group terminals having similar service characteristics or traffic characteristics. The AP 110 may group the STA1 121, the STA2 122, and the STA3 123 having similar service characteristics or traffic characteristics into one group 120. In addition, the AP 110 may group the STA4 131, the STA5 132, and the STA6 133 having similar service characteristics or traffic characteristics into one group 130. In addition, the AP 110 may group the STA7 141, the STA8 142, and the STA9 143 having similar service characteristics or traffic characteristics into one group 140.

The AP 110 allows the

groups

120, 130, and 140 to belong to the group 120 to perform channel access by waking at different times for each group. In operation 140, information on a group delivery traffic indication map (DTIM) transmission period having different values may be broadcast. The terminals belonging to each group may receive information on a group delivery traffic indication map (DTIM) transmission period and then wake up based on the information, and receive group delivery traffic indication map (DTIM) information corresponding to each group. The group DTIM information indicates whether there is data buffered for corresponding terminals for each group through a bit value. If the terminal determines that there is buffered data based on the group DTIM information, the terminal may request the buffered data from the AP 110.

In addition, when the number of terminals included in the group 120 is greater than a preset criterion, the AP 110 may generate the subgroup 125 to satisfy the preset criterion. The preset criterion may be determined according to the type, number, and state of channels supported by the AP 110. In addition, the preset criteria may be variously defined according to more specific service characteristics or traffic characteristics.

For example, if the preset criteria are two terminals, the subgroup 125 may include the STA2 122 and the STA3 123. As another example, the subgroup 125 may include the STA1 121 and the STA2 122, or may include the STA1 121 and the STA3 123. Similarly with respect to the other group 130 and the group 140, the AP 110, if the number of terminals included in the group 130 and the group 140 is larger than the preset criteria, the subgroup 135 to satisfy the preset criteria And a subgroup 145. The subgroup 135 may include a STA5 132 and a STA6 133. The subgroup 145 may include the STA8 142 and the STA9 143.

As another example, if there are a plurality of subgroups 125 in the same group 120, the transmission period of the group DTIM is the same for the plurality of subgroups, and offset values may be set differently. Terminals belonging to the subgroups receive group information from the AP 110 through the beacon, and based on the transmission period and offset value of the group DTIM included in the group information, the transmission period of the group DTIM of the subgroup to which they belong, and At a point corresponding to the offset value, the user can receive group DTIM information. Accordingly, even in the same group, terminals belonging to different subgroups may wake up at different times to perform channel access. As a result, the probability of occurrence of collision due to channel access between the terminals is reduced, thereby reducing the energy consumed by the terminals.

Frames transmitted to the terminals STA1, STA2, STA3, STA4, STA5, STA6, STA7, STA8, and STA9 may be classified into broadcast frames, multicast frames, and unicast frames according to their delivery ranges.

The broadcast frame and the multicast frame may be transmitted in group DTIM interval units longer than the beacon interval without being transmitted to all beacons. The unicast frame may transmit group DTIM information in units of beacon intervals or listen intervals.

The AP 110 may group the terminals based on an association ID (AID) assigned to the terminals STA1, STA2, STA3, STA4, STA5, STA6, STA7, STA8, and STA9. For example, the upper two MSBs of the AID may be grouped with the same terminals in one group.

The AP 110 may reduce the number of terminals performing channel access to transmit a PS-POLL frame or a trigger frame by fragmenting DTIM for each group and transmitting group DTIM information.

The transmission period of the group DTIM is different for each group, and the transmission period of the group DTIM may be set according to the service characteristics or traffic characteristics of the group.

The AP 110 sets and transmits a transmission period of the group DTIM based on information informed by the terminals STA1, STA2, STA3, STA4, STA5, STA6, STA7, STA8, and STA9. If the characteristic requested by the terminal is not reflected in the transmission period of the group DTIM, the AP 110 may negotiate with the terminal by defining and notifying a status.

The AP 110 may generate group information including information on the grouped group, a transmission period of the group DTIM set for each group, and an offset value set in the subgroup when generating a subgroup, and assign the group information to the terminals.

For example, the group information may include a Group DTIM delivery interval indicating a transmission period of the group DTIM, a group DTIM ID for identifying each group, a group DTIM counter for indicating when the group DTIM information is transmitted, and an offset counter. .

The group DTIM counter may include a counter ID for identifying the counter and a current count field indicating the value of the counter in the current beacon. The count value of the current count field may be adjusted in units of transmission periods of the group DTIM.

The offset counter indicates an offset value of the offset counter currently included in the beacon, and the offset value may be adjusted in units of beacon intervals. Alternatively, an offset counter interval field indicating a unit in which an offset value is adjusted may be added, and a value of this field may be determined as an integer multiple of a beacon interval.

For example, groups having the same group DTIM transmission period may share the same group DTIM counter. Subgroups within the same group may be distinguished by different offset values of the offset counter. For example, the first subgroup may be assigned an offset value of 0, and the second subgroup may be assigned another offset value as an offset value.

After allocating group information to terminals, the AP 110 inserts a newly defined group DTIM descriptor element for each beacon, and transmits group DTIM information to the terminal.

The group DTIM descriptor element may include a group DTIM counter and an offset counter. The group DTIM counter may be identified between counters by a counter ID, and each counter may have a value corresponding to a different group DTIM transmission period.

The value of the current count field may decrease by one for each group DTIM transmission period. When the value of the current count field is 0, the AP 110 may transmit buffered data (or buffered group addressed frame) of the group having the offset value 0 to the corresponding group.

The offset counter may be configured in pairs with the group DTIM counter. When the count value of the paired group DTIM counter becomes 0, the offset counter is triggered, and the offset value may be increased by 1 according to the set offset unit. For example, when the beacon interval is set as an offset value adjusting unit, the offset value may increase by 1 for every beacon interval.

If the count value of the group DTIM counter is not 0, the offset counter does not operate. Therefore, to reduce the number of bits in the beacon frame, the offset counter field is dynamically inserted into the beacon frame only when the count value of the group DTIM counter is 0. It may be.

After transmitting the group DTIM descriptor element, the AP 110 may transmit the buffered data of the group matching the offset value to the corresponding group.

When the AP 110 completes the transmission of the buffered data to all groups having the offset value, the AP 110 may reset the group DTIM counter and the offset counter.

In addition, the group DTIM descriptor element may include a group DTIM ID. The group DTIM ID may be used to identify grouped groups, may be used to identify a group in which buffered data exists, or may be used to distinguish each group when a plurality of groups share one group DTIM counter. .

The terminals STA1, STA2, STA3, STA4, STA5, STA6, STA7, STA8, and STA9 may be configured to indicate the value of the group DTIM counter and the offset counter of the group DTIM descriptor element inserted into the receiving beacon, By comparing the transmission period, count value and offset value of the allocated group DTIM, it is possible to predict when the group DTIM information of the group to which it belongs is transmitted. Therefore, when a terminal hears any one beacon, it can acquire a transmission time of group DTIM information of a group to which it belongs. In addition, the terminals may check the presence or absence of data buffered based on the group DTIM ID.

2 is a block diagram of an apparatus for controlling transmission schedule of data buffered in a WLAN according to an embodiment of the present invention.

2, the apparatus 200 for transmitting transmission of data buffered in a WLAN according to an embodiment includes a grouping unit 210, a group information allocating unit 220, a transmitter 230, and a receiver 240. It may include. The transmission schedule control apparatus 200 for data buffered in a WLAN according to an embodiment corresponds to an access point in a WLAN environment.

The receiver 240 receives service characteristics and traffic characteristics from the terminals. The information on the traffic characteristics may be TCLAS (Traffic Class) information used in IEEE 802.11e, and the information on the service characteristics may be access category (AC) information of EDCA (Enhanced Distributed Channel Access).

The grouping unit 210 may group the terminals based on at least one of service characteristics and traffic characteristics of the terminals. The grouping unit 210 may group terminals having similar service characteristics or group terminals having similar traffic characteristics. In addition, the grouping unit 210 may group terminals having similar service characteristics and traffic characteristics.

The grouping unit 210 may group the terminals on the basis of an association identifier (AID) associated with a traffic indication map (TIM) indicating whether a frame buffered at the access point is present.

The grouping unit 210 may group the terminals included in the grouped group into subgroups including a predetermined number or less. If there are many terminals included in the group and it is determined that there is a high possibility of collision in performing channel access to the access point, the grouping unit 210 may group the group into subgroups again.

The group information allocator 220 may allocate group information to wake up at different times for each grouped group.

The group information may include a transmission period of the group DTIM, a group identifier, a counter ID (ID, Identifier) and a current count value of the group counter, and an offset value of the offset counter.

For example, the group information allocator 220 may include a transmission period determiner 221, an identifier generator 223, a group counter 225, and an offset counter 227.

The transmission period determining unit 221 may determine the transmission period of the group DTIM representing the existence of the buffered data corresponding to the terminal belonging to the grouped group differently between groups. Since the transmission period of the group DTIM is determined differently for each group, the group may wake up at different times for each group and receive the buffered data from the access point.

The identifier generator 223 may generate a group identifier for identifying the grouped group. The access point may identify a grouped group by using a group identifier, and the terminal may identify a group to which it belongs by using a group identifier. The access point may transmit the group DTIM to the waking group using the group identifier.

The group counter 225 may set the count value in conjunction with the group DTIM transmission period determined by the transmission period determining unit 221 to inform the terminals of the transmission time of the group DTIM.

The count value of the group counter 225 may be determined based on the transmission period of the group DTIM.

The offset counter 227 may indicate when to transmit the group DTIM of the subgroup by setting an offset value to the subgroup of the grouped group. In the same group, the group counters assigned by the terminals have the same count value. If there is a subgroup, it may be distinguished between the subgroups through an offset value.

The offset value of the offset counter 227 may be determined based on the transmission period of the beacon transmitted by the transmitter 230. Alternatively, the offset value may be adjusted based on an integer multiple of the transmission period of the beacons.

The transmitter 230 may transmit at least one of group delivery traffic indication map (DTIM) information and buffered data based on group information allocated for each group. The group DTIM information means a group DTIM indicating presence or absence of data buffered for each group. In response to the transmission of the group DTIM, the receiver 240 may receive a PS-Poll frame or a trigger frame from the terminal. The transmitter 230 may transmit the buffered data in response to the PS-Poll frame or the trigger frame.

The transmitter 230 may transmit the group information allocated by the group information allocator 220 to the grouped groups. The transmitter 230 may include group information in the beacon and transmit the groups. For example, the transmitter 230 may transmit group information in a broadcast or multicast manner. For example, the transmitter 230 may transmit the buffered data in a unicast manner.

After the group information is allocated to the group, the transmitter 230 may insert a group DTIM descriptor element updated at every transmission time of the beacon into the beacon and transmit the group DTIM descriptor element.

The group DTIM descriptor element may include a count value of the group counter 225 decrementing by 1 for each transmission period of the group DTIM, and an offset value of the offset counter 227 that increases by 1 for each transmission period of the beacon when the count value becomes zero. It may include.

When the count value is 0, the transmitter 230 may transmit group DTIM information of a group having an offset value of zero.

After the count value becomes 0, if the offset value increases for each transmission period of the beacon, the transmitter 230 may transmit group DTIM information of the group corresponding to the increased offset value.

Referring to FIG. 3, a terminal 300 that receives data buffered based on a transmission schedule in a WLAN according to an embodiment includes a receiver 310, a calculator 320, a requester 330, and a transmitter ( 340 may be included.

The receiver 310 may receive a beacon including group information and a group DTIM descriptor element from the access point.

The group DTIM descriptor element may include a count value decremented by 1 for each transmission period of the group DTIM, and an offset value that increases by 1 for each transmission period of the beacon when the count value becomes zero.

The calculation unit 320 may calculate the transmission time of the group delivery traffic indication map (DTIM) of the group to which the terminal 300 belongs by comparing the group information and the group DTIM descriptor element updated for each transmission period of the beacon.

For example, the calculator 320 may include an identifier 321, a comparator 323, and an estimator 325.

The identification unit 321 may identify a group to which the terminal 300 belongs, based on the group identifier received by the reception unit 310.

The comparison unit 323 may compare the transmission period of the group DTIM and the count value of the group DTIM descriptor element with respect to the identified terminal 300, and compare the offset value of the offset counter and the offset value of the group DTIM descriptor element. .

The estimator 325 may estimate the transmission time of the group DTIM based on the comparison result of the comparator 323. For example, the estimator 325 may estimate the transmission time of the group DTIM based on the difference between the count value of the group counter allocated to reflect the transmission period of the group DTIM and the count value of the group DTIM descriptor element. .

In addition, if the value of the assigned group counter and the count value of the group DTIM descriptor element are the same, the estimator 325 determines the transmission time of the group DTIM based on the difference between the offset value of the offset counter and the offset value of the group DTIM descriptor element. It can be estimated.

The requester 330 may wake up based on the transmission time calculated by the calculator 320, and request the buffered data to the access point based on the received group DTIM information.

The transmitter 340 may transmit at least one of a service characteristic and a traffic characteristic of the terminal 300 to the access point.

On the basis of the group DTIM information, when it is confirmed that there is data buffered in the terminal 300, the transmitter 340 transmits a PS-Poll (Power Save Poll) frame or trigger frame requesting the buffered data to the access point. The receiver 310 may receive the buffered data in response to the PS-Poll frame or the trigger frame.

In operation 410, the communication device may group terminals based on at least one of service characteristics and traffic characteristics of the terminals. Here, the communication device may correspond to an access point.

The communication apparatus according to an embodiment may group the terminals included in the grouped group into subgroups including the terminal or less. Transmission periods of different group DTIMs may be set between groups, and transmission periods and different offset values of the same group DTIM may be set between subgroups.

In operation 420, the communication apparatus according to an embodiment may allocate group information to wake up at different times for each grouped group. The group information may include a transmission period of the group DTIM, a group identifier, a counter ID (ID, Identifier) and a current count value of the group counter, and an offset value of the offset counter.

According to an embodiment, the communication apparatus may determine a transmission period of a group DTIM representing a presence of buffered data corresponding to terminals belonging to a grouped group differently from one group to another.

The communication device according to an embodiment may generate a group identifier for identifying a grouped group. The communication apparatus according to an embodiment may inform the terminal of the transmission time of the group DTIM by setting a count value of the group counter in association with the determined group DTIM transmission period. The communication apparatus according to an embodiment may inform the transmission time of different group DTIMs between subgroups by setting an offset value of an offset counter in a subgroup of a grouped group.

In operation 430, the communication apparatus may transmit at least one of group delivery traffic indication map (DTIM) information and buffered data based on group information allocated for each group.

The communication device according to an embodiment may transmit the allocated group information to the grouped groups.

In operation 511, the AP 503 according to an embodiment may receive information about a service characteristic and a traffic characteristic from the STA1 501. In operation 513, the AP 503 according to an embodiment may receive information about a service characteristic and a traffic characteristic from the STA2 505.

In operation 515, the AP 503 may group the STA1 501 and the STA2 505 based on the service characteristic and the traffic characteristic. STA1 501 and STA2 505 are the simplest configuration used to represent a plurality of terminals, and two or more terminals may be grouped into the same group according to similar service characteristics or similar traffic characteristics.

In operation 517, the AP 503 may allocate group information to the group. The group information may include a transmission period of the group DTIM, a group identifier, a counter ID (ID, Identifier) and a current count value of the group counter, and an offset value of the offset counter.

In operation 519, the AP 503 may transmit group information to the group to which the STA1 501 belongs. In operation 521, the AP 503 may transmit group information to the group to which the STA2 505 belongs. The group to which the STA1 501 belongs and the group to which the STA2 505 belongs may or may not be the same.

In operation 523, the AP 503 may transmit group DTIM information to the group to which the STA1 501 belongs, according to the transmission period of the determined group DTIM. In step 525, the AP 503 may transmit the group DTIM information to the group to which the STA2 505 belongs according to the determined transmission period of the group DTIM. If the group to which the STA1 501 belongs and the group to which the STA2 505 belongs are the same, the transmission periods of the group DTIM received by the STA1 501 and the STA2 505 are the same, and the group to which the STA1 501 belongs and STA2 ( If the group to which the 505 belongs is different, the transmission period of the group DTIM received by the STA1 501 and the STA2 505 is also different.

In operation 527, the STA1 501 may transmit a PS-Poll frame or a trigger frame to the AP 503 when it is determined that there is buffered data through the group DTIM information. The PS-Poll frame or trigger frame contains a request message of buffered data. In operation 529, the STA2 505 may transmit a PS-Poll frame or a trigger frame to the AP 503 when it is determined that there is buffered data through the group DTIM information.

In operation 531, the AP 503 may transmit the buffered data to the STA1 501 in response to the PS-Poll frame or the trigger frame. In operation 533, the AP 503 may transmit data buffered to the STA2 505 in response to the PS-Poll frame or the trigger frame.

The method according to the embodiment may be embodied in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

Although the embodiments have been described by the limited embodiments and the drawings as described above, various modifications and variations are possible to those skilled in the art from the above description. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the described method, or other components. Or even if replaced or substituted by equivalents, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are within the scope of the claims that follow.

Claims

A grouping unit that groups the terminals based on at least one of a service characteristic and a traffic characteristic of the terminals;

A group information allocator for allocating group information to wake up at different times for each of the grouped groups; And

A transmitter for transmitting at least one of group delivery traffic indication map (DTIM) information and buffered data based on the allocated group information

Transmission schedule control apparatus of the data buffered in the WLAN comprising a.
The method of claim 1,

The grouping unit

Grouping terminals on the basis of an association identifier (AID) associated with a traffic indication map (TIM) indicating the presence or absence of a buffered frame at the access point

An apparatus for controlling transmission schedule of data buffered in a WLAN.
The method of claim 1,

The grouping unit

The UEs included in the grouped group are regrouped into subgroups including a predetermined number or less.

An apparatus for controlling transmission schedule of data buffered in a WLAN.
The method of claim 1,

The group information allocating unit

A transmission period determining unit configured to determine a transmission period of a group DTIM differently between the groups, indicating a presence of buffered data corresponding to a terminal belonging to the grouped group;

An identifier generator for generating a group identifier for identifying the grouped group;

A group counter indicating a transmission time of the group DTIM by setting a count value in association with the group DTIM transmission period determined by the transmission period determining unit; And

An offset counter for indicating when to transmit a group DTIM of the subgroup by setting an offset value to a subgroup of the grouped group

Transmission schedule control apparatus of the data buffered in the WLAN comprising a.
The method of claim 4, wherein

The group information is

Transmission period of the group DTIM, the group identifier, the counter ID (ID, Identifier) and the current count value of the group counter, the offset value of the offset counter

Transmission schedule control apparatus of the data buffered in the WLAN comprising a.
The method of claim 4, wherein

The count value of the group counter is

Determined based on the transmission period of the group DTIM

An apparatus for controlling transmission schedule of data buffered in a WLAN.
The method of claim 1,

The offset value of the offset counter is

Determined based on the transmission period of the beacons transmitted by the transmitter

An apparatus for controlling transmission schedule of data buffered in a WLAN.
The method of claim 5,

The transmission unit

Transmitting the group information allocated by the group information allocator to the grouped groups

An apparatus for controlling transmission schedule of data buffered in a WLAN.
The method of claim 1,

The transmission unit

After the group information is assigned to the group, a group DTIM descriptor element updated at every transmission time is inserted into a beacon and transmitted.

An apparatus for controlling transmission schedule of data buffered in a WLAN.
The method of claim 9,

The group DTIM descriptor element includes a count value that decreases by one for each transmission period of the group DTIM, and an offset value that increases by one for each transmission period of the beacon when the count value becomes 0,

When the count value is 0, the transmitter transmits group DTIM information of a group having the offset value of 0,

The transmission unit transmits group DTIM information of a group corresponding to the increased offset value when the offset value increases for each transmission period of the beacon after the count value becomes 0.

An apparatus for controlling transmission schedule of data buffered in a WLAN.
A receiver for receiving a beacon including group information and a group DTIM descriptor element from the access point;

A calculation unit comparing the group information with the group DTIM descriptor element updated for each transmission period of the beacon, and calculating a transmission time of the group delivery traffic indication map (DTIM) of the group to which the terminal belongs; And

A request unit for waking up based on the calculated transmission time point and requesting the buffered data to the access point.

Terminal for receiving the buffered data on the basis of a transmission schedule in a WLAN.
The method of claim 11,

The group information is

Transmission period, group identifier, counter ID (ID, Identifier) and current count value of the group DTIM, offset value of the offset counter

A terminal for receiving the buffered data based on a transmission schedule in a WLAN comprising a.
The method of claim 12,

The group DTIM descriptor element is

A count value decremented by 1 for each transmission period of the group DTIM, and an offset value that increases by 1 per transmission period of the beacon when the count value becomes 0

A terminal for receiving the buffered data based on a transmission schedule in a WLAN comprising a.
The method of claim 13,

The calculation unit

An identification unit for identifying a group to which the terminal belongs, based on the group identifier;

A comparison unit comparing the transmission period of the group DTIM, the count value of the group DTIM descriptor element, the offset value of the offset counter, and the offset value of the group DTIM descriptor element for the identified terminal; And

An estimator for estimating the transmission time of the group DTIM based on the comparison result

Terminal for receiving the buffered data on the basis of a transmission schedule in a WLAN.
The method of claim 11,

Transmitter for transmitting at least one of the service characteristics and traffic characteristics of the terminal to the access point

Terminal for receiving the buffered data on the basis of the transmission schedule in a WLAN further comprising a
The method of claim 15,

The transmission unit transmits a PS-Poll (Power Save Poll) frame or trigger frame requesting the buffered data to the access point,

The receiving unit receives the buffered data in response to the PS-Poll frame or the trigger frame.

A terminal for receiving data buffered based on a transmission schedule in a WLAN.
Grouping the terminals based on at least one of a service characteristic and a traffic characteristic of the terminals;

Allocating group information to wake up at different times for each of the grouped groups; And

Transmitting at least one of group delivery traffic indication map (DTIM) information and buffered data based on the assigned group information

Method of controlling a transmission schedule of the buffered data in a WLAN comprising a.
The method of claim 17,

The grouping step

Grouping the terminals included in the grouped group into subgroups having a predetermined number or less;

Method of controlling a transmission schedule of the buffered data in a WLAN comprising a.
The method of claim 17,

The assigning step

Determining a transmission period of a group DTIM differently between the groups, indicating a presence of buffered data corresponding to a terminal belonging to the grouped group;

Generating a group identifier identifying the grouped group;

Informing a transmission time of a group DTIM by setting a count value of a group counter in association with the determined group DTIM transmission period; And

Informing the transmission time of the group DTIM of the subgroup by setting an offset value of an offset counter in the subgroup of the grouped group

Method of controlling a transmission schedule of the buffered data in a WLAN comprising a.
The method of claim 19,

The transmitting step

Transmitting the allocated group information to the grouped groups

Method of controlling a transmission schedule of the buffered data in a WLAN comprising a.