WO2009035289A2

WO2009035289A2 - Radio measurement procedures for wireless local area network and wireless station supporting the procedures

Info

Publication number: WO2009035289A2
Application number: PCT/KR2008/005404
Authority: WO
Inventors: Yongho Seok
Original assignee: Lg Electronics Inc.
Priority date: 2007-09-12
Filing date: 2008-09-12
Publication date: 2009-03-19
Also published as: WO2009035289A3

Abstract

Provided are a radio measurement procedure in a wireless local area network and a device supporting the radio measurement procedure. In the radio measurement procedure for measuring station statistics in the WLAN, a requesting station transmits a triggered station statistics request message, which includes trigger conditions and requests a triggered reporting process from an aggregate-MAC service data unit (A-MSDU) or an aggregate-MAC protocol data unit (A-MPDU) counter to a requested station. In a case where the trigger conditions occur in the A- MSDU or A-MPDU counter as a result of measurement, the requested station transmits a station statistics report message including requested statistics information to the requesting station.

Description

RADIO MEASUREMENT PROCEDURES FOR WIRELESS

LOCAL ACCESS NETWORK AND WIRELESS STATION

SUPPORTING THE PROCEDURES

Technical Field

[1] The present invention relates to wireless communication, and more particularly, to a radio measurement procedure for station (STA) statistics in a wireless local area network (WLAN) and a device supporting the radio measurement procedure. Background Art

[2] With development of information communication technologies, a variety of wireless communication technologies have been developed. A wireless LAN (WLAN) is a technology permitting wireless access to the Internet in specific service areas such as home or companies or air planes by the use of portable terminals such as a personal digital assistant (PDA), a laptop computer, and a portable multimedia player (PMP) on the basis of a radio frequency technology.

[3] Recently, as a supply of equipments for the WLAN has been increased, users of potable terminals such as laptop computers can perform their tasks with increased mobility. For example, the users can attend a conference with their laptop computers from their desk. In this case, it is possible to import data while maintaining access to a local network. In addition, the users can access the Internet through one more modems or gateways present on the local network without wired connection. Similarly, business travelers commonly use their portable terminals to gain access to their email accounts, to check if there is any unread email, and to read and send email.

[4] In the initial WLAN technology, a data rate of 1 to 2 Mbps was supported by the use of frequency hopping, spread spectrum, and infrared communication using a frequency of 2.4 GHz in accordance with the IEEE 802.11. In recent years, with the development of the wireless communication technology, 54 Mbps in maximum can be supported by applying the orthogonal frequency division multiplex (OFDM) technology, etc. to the WLAN. In the IEEE 802.11, a wireless communication technology for improvement in quality of service (QoS), compatibility of access point (AP) protocol, security enhancement, radio resource measurement, radio resource measurement, wireless access in vehicular environment, fast roaming, mesh network, inter- working with external network, wireless network management, and the like is developed and implemented or being developed now.

[5] In the radio resource measurement procedure, an STA directly observes radio link performance and radio environments and/or gather data on radio link performance and radio environments measured by another STA. The radio resource measurement procedure is used to recognize radio environments of the STA. For example, the STA may locally measure the radio environments in a direct manner. Alternatively, the STA may request another STA to measure one or more elements. The STA may receive a request for measuring one or more elements from another STA and inform the measurement result to the STA. The radio measurement data obtained through this procedure may be used to manage the STA and radio resources. Alternatively, the radio measurement data may be provided to an upper protocol layer for various applications.

[6] A variety of means can be used for the radio resource measurement in the wireless network. For example, beacon frames or measurement pilots having a predetermined format can be used for the radio resource measurement. A method of calculating a channel load or a noise histogram may be used therefor. A method using statistical information of STAs can be used for the radio resource measurement. In this case, values recorded in various counters of the STA or BSS (Basic Service Set) average access delay time can be contained in the statistical information.

[7] As described above, the STA include a plurality of counters so as to calculate an accumulation of various types of statistical information (hereinafter, referred to as 'STA statistical element'). For example, STA statistical elements measured by the counters of the STA include transmitted fragment counts, multicast transmitted frame counts, failed counts, retry count, multiple retry count, frame duplicate count, acknowledgement failure count, request to send (RTS) success count, RTS failure count, discarded frame count, and/or transmitted frame count, and the like.

[8] In the current wireless communication standard, various types of STA statistical elements are defined. In addition, some STA statistics elements are managed by distinguishing a case where a corresponding STA supports quality of service (QoS) from a case where a corresponding STA does not support QoS. Thus, there are more various STA statistics elements than the aforementioned STA statistics elements. Accordingly, accurate, systematic, and efficient procedures for measuring wireless resources and a device therefore are required so as to exchange information on the plurality of STA statistical elements.

[9] On the other hand, IEEE 802.1 In is a technical standard that is recently established so as to overcome a limit in communication speed that is a weak point of a wireless LAN. The IEEE 802.1 In is used so as to increase a speed and reliability of a network and extend a service area of a wireless network. More specifically, in the IEEE 802.1 In a high throughput (HT) in which a data processing speed is equal to or greater than 100 Mbps to the maximum extent is supported. The IEEE 802.1 In is based on multiple inputs and multiple outputs (MIMO) technology in which multiple antennas are used for both ends including transmitting and receiving units so as to minimize a transmission error and optimize a data speed. In addition, in the IEEE 802.1 In, a coding method in which a plurality of copies are transmitted so as to increase data reliability is used, and orthogonal frequency division multiplex (OFDM) technology is used.

Disclosure of Invention Technical Problem

[10] The present invention provides a radio measurement procedure related to station

(STA) statistics for enabling a wireless network to be effectively managed in a wireless local area network (WLAN) that supports the IEEE. 802.1 In and a device supporting the radio measurement procedure.

[11] The present invention also provides a radio measurement procedure related to a triggered STA statistics request/report so that information is exchanged only when a condition specified in a WLAN that supports the IEEE 802.1 In is satisfied and a device supporting the radio measurement procedure.

[12] The present invention also provides a method of constructing a frame for performing the radio measurement procedure related to the triggered STA statistics request/report. Technical Solution

[13] According to an aspect of the present invention, there is provided a radio measurement procedure for measuring station statistics in a wireless local area network (WLAN), comprising: transmitting a triggered station statistics request message, which includes trigger conditions and requests a triggered reporting process from an aggregate-MAC service data unit (A-MSDU) counter, to a requested station; and receiving a station statistics report message including requested statistics information from the requested station in a case where the trigger conditions occur in the A-MSDU counter.

[14] In the above aspect of the present invention, the triggered station statistics request message may includes: a group identity field for indicating a requested A-MSDU statistics group; and a triggered reporting field for the A-MSDU counters used to specify the trigger conditions, and the trigger conditions may include reporting triggers and an A-MSDU count threshold for a corresponding reporting trigger. In addition, the triggered reporting field for the A-MSDU counter may include: an A-MSDU counter trigger condition subfield including a plurality of bit fields for specifying the reporting triggers; and one or more A-MSDU count threshold subfields for specifying a value for representing the number of A-MSDUs which is used as a threshold for a corresponding reporting trigger, and each of the one or more A-MSDU count threshold subfields may exist only in a case where a corresponding bit field in the A-MSDU counter trigger condition subfield is set to '1'.

[15] According to another aspect of the present invention, there is provided a radio measurement procedure for measuring station statistics in a WLAN, comprising: transmitting a triggered station statistics request message, which includes trigger conditions and requests a triggered reporting process from an aggregate-MAC protocol data unit (A-MPDU) counter, to a requested station; and receiving a station statistics report message including requested statistics information from the requested station in a case where the trigger conditions occur in the A-MPDU counter.

[16] In the above aspect of the present invention, the triggered station statistics request message may include: a group identity field for indicating a requested A-MPDU statistics group; and a triggered reporting field for the A-MPDU counters used to specify the trigger conditions, and the trigger conditions may include reporting triggers and an A-MPDU count threshold for a corresponding reporting trigger.

[17] According to another aspect of the present invention, there is provided a radio measurement procedure for measuring station statistics in a WLAN, comprising: receiving a triggered station statistics request message, which includes trigger conditions and requests a triggered reporting process from an A-MSDU or an A- MPDU counter, from a requesting station; and measuring requested A-MSDU or A- MPDU station statistics; and transmitting a station statistics report message including measured A-MSDU or A-MPDU station statistics information to the requesting station in a case where the trigger conditions occur in the A-MSDU or A-MPDU counter as a result of measurement.

Advantageous Effects

[18] In a radio measurement procedure in a wireless communication system that supports the IEEE 802.1 In according to an embodiment of the present invention, a requesting STA can acquire STA statistics data related to an aggregate-MAC service data unit (A-MSDU) and an aggregate-MAC protocol data unit (A-MPDU). An access point (AP) can efficiently manage wireless network resources by using the acquired STA statistics data related to the A-MSDU and the A-MPDU.

[19] In addition, according to an embodiment of the present invention, in a case where desired STA statistics data has relation to the A-MSDU or A-MPDU, it is possible to perform a triggered STA statistics request and report procedure in which a requesting STA specifies a condition for triggering a reporting process of a requested STA. It is possible to lessen loads of a wireless communication system due to acquisition of statistics data related to the A-MSDU or A-MPDU by using the triggered STA statistics request and report procedure. More specifically, it is possible to reduce loads of the requesting STA which has to transmit a request frame whenever statistics data is necessary by using the triggered statistics request and report procedure and to increase the efficiency of wireless resources by reducing unnecessary signaling.

Brief Description of the Drawings [20] FIG. 1 is a schematic diagram illustrating an infrastructure basic service set (BSS) as an example of a wireless LAN according to an embodiment of the present invention. [21] FIG. 2 is a schematic diagram illustrating an independent BSS as an example of a wireless LAN according to another embodiment of the present invention. [22] FIG. 3 is a functional block diagram illustrating a procedure of managing a wireless network according to an embodiment of the present invention. [23] FIG. 4 is a block diagram illustrating an aggregate-MAC service data unit

(A-MSDU) format. [24] FIG. 5 is a functional block diagram illustrating a triggered STA statistics request for an aggregate-MAC protocol data unit (A-MPDU) and an A-MSDU in a wireless network system that supports the IEEE 802.1 In according to an embodiment of the present invention. [25] FIG. 6 is a block diagram illustrating an example of an example of a triggered radio measurement request frame according to an embodiment of the present invention. [26] FIG. 7 is a block diagram illustrating an example of a format of a triggered reporting subfield of FIG. 6 for an A-MSDU STA counter. [27] FIG. 8 is a block diagram illustrating an example of a format of a trigger condition field of the A-MSDU STA counter of FIG 7. [28] FIG. 9 is a block diagram illustrating an example of a format of the triggered reporting subfield of FIG. 6 with respect to an A-MPDU STA counter. [29] FIG. 10 is a block diagram illustrating an example of a format of the A-MPDU STA counter trigger condition field of FIG. 9. [30] FIG. 11 is a block diagram illustrating an example of a format of a radio measurement report frame according an embodiment of the present invention. [31] FIG. 12 is a block diagram illustrating an example of a format of a statistic group data unit for an A-MSDU STA counter of FIG. 11. [32] FIG. 13 is a block diagram illustrating an example of a format of a reporting reason unit for an A-MSDU STA counter of FIG. 11. [33] FIG. 14 is a block diagram illustrating an example of a format of a statistical group data unit for an A-MPDU STA counter of FIG. 11. [34] FIG. 15 is a block diagram illustrating an example of a reporting reason unit for an

A-MPDU STA counter of FIG. 11.

Best Mode for Carrying Out the Invention [35] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments should be considered in descriptive sense only and not for purpose of limitation.

[36] FIGS. 1 and 2 illustrate schematic structures of examples of a wireless LAN system according to embodiments of the present invention.

[37] Referring to FIGS. 1 and 2, the wireless LAN system includes one or more basic service sets (BSSs). A BSS is a set of stations (STAs) which communicate with one another in successful synchronization with one another. The BSS does not indicate a specific area. BSSs are classified into infrastructure BSSs and independent BSSs (IBSS). The former is shown in FIG. 1, and the latter is shown in FIG. 2. The infrastructure BSSs BSSl and BSS2 include one or more STAs STAl, STA3, and STA4, access points APs that are STAs for providing a distribution service, and a distribution system DS for connecting a plurality of APs API and AP2 to each other. On the other hand, since the IBSS includes no AP, all the STAs are mobile stations STA6, STA7, and STA8. Since the STAs are not permitted to access a DS, the STAs constitute a self-contained network.

[38] An STA is an optional function medium including a medium access control (MAC) based on rules of the IEEE 802.11 standard and a physical layer interface for a wireless medium. In a broad sense, STAs include both AP and non-AP stations. An STA for wireless communication includes a processor, a transceiver, a user interface, a display unit, and the like. The processor is a functional unit designed to generate a frame to be transmitted through a wireless network or process a frame received through the wireless network. The process performs various functions for controlling the station. The transceiver that is functionally connected to the processor is a unit designed to transmit and receive a frame through the wireless network for the station.

[39] Mobile terminals handled by a user among the STAs are non-AP STAs STAl, STA3,

STA4, STA6, STA7, and STA8. STAs may simply indicate non-AP STAs. A non-AP STA may be referred to a wireless transmit/receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile terminal, or a mobile subscriber unit.

[40] The APs API and AP2 are functional entities for connecting an associated station to the DS via a wireless medium. In the infrastructure BSS including APs, non-AP STAs communicate with one another via APs, in principle. In a case where direct links are established, non-AP STAs can communicate with one another. An AP may be referred to a central controller, a base station (BS), a node-B, a base transceiver system (BTS), or a site controller, instead of an access point.

[41] A plurality of infrastructure BSSs may be connected to one another via a distribution system (DS). The plurality of BSSs connected to one another via the DS may be referred to as an extended service set (ESS). The STAs included in the ESS may communicate with one another. Non-AP STAs belonging to the same ESS can moves to another BSS while continuously communicating with one another.

[42] The DS is a mechanism for enabling one AP to communicate with another AP. It is possible for an AP to transmit a frame for STAs associated with the BSS managed by the AP, to transmit a frame in a case where one STA moves to another BSS, or to transmit a frame with an external network such as a wired network, by using the DS. The DS don't need to be a network. If the DS can provide a predetermined distribution service defined in the IEEE 802.11, the DS has any form. For example, the DS may be a wireless network such as a mesh network or a physical structure for connecting APs to one another.

[43] FIG. 3 is a functional block diagram illustrating a procedure of managing a wireless network according to an embodiment of the present invention, in the wireless LAN system shown in FIG. 1 or FIG. 2 or in a wireless communication system that is practically equal to the wireless LAN system. The functional block diagram between a first STA(2) and a second STA(4) shown in FIG. 3 may be a procedure performed between a non-AP STA and an AP, which constitute an infrastructure BSS of the wireless LAN system. It is apparent that the embodiment is not limited thereto. A radio measurement procedure according to an embodiment of the present invention to be described may be applied to a case where the wireless LAN system supports the IEEE 802. Hn.

[44] Referring to FIG. 3, the radio measurement procedure in a radio communication system according to the embodiment of the present invention includes a scanning procedure SlO, an authentication procedure S20, and/or an association procedure S30 as preliminary procedures, and a radio measurement procedure S40 that is performed after the preliminary procedures SlO to S30. According to the embodiment of the present invention, some procedures among the preliminary procedures may be optional procedures.

[45] Referring to FIG. 3, the scanning procedure SlO is firstly performed between the first

STA(I) and the second STA(2). In the scanning procedure SlO, the first STA(I) searches for a candidate station to be associated in the association procedure S30. For example, in the scanning procedure SlO, a non-AP STA searches for an AP, in the infrastructure BSS. However, in a broad sense, the scanning procedure SlO may include a procedure in which a non-AP STA searches for a neighboring non-AP STA in a case of the IBSS or a procedure of searching for a neighboring MP in a case of a mesh network.

[46] The scanning procedure has two types. A first type is a passive scan method using a beacon frame transmitted from the second STA(4). Accordingly, the first STA(2) which desires to access a wireless LAN can search for an accessible BSS by receiving a beacon frame which is periodically transmitted from the second STA(4) that is an AP for managing a corresponding BSS (or IBSS). The passive scan method may be applied to a case where the second STA(4) is an AP which transmits a beacon frame.

[47] A second type is an active scan method. Accordingly, the first STA(2) which desires to access a wireless LAN firstly transmits a probe request frame. Then, the second STA(4) which receives the probe request frame, for example, an AP transmits a probe response frame including information on a service set ID (SSID) of the BSS managed by the AP and capability supported by the AP to the first STA(2). Accordingly, the first STA(2) can recognize existence of a candidate AP and various types of information on the candidate AP through the received probe response frame.

[48] In the scanning procedure SlO, in a case where the second STA(4) which transmits a beacon frame or probe response frame and the first STA(2) which transmits a probe request frame support the IEEE 802. l ie and the IEEE 802.1 In, the beacon frame or probe request/response frame may include information on this. For example, the first STA(2) and the second STA(4) can information a function supported by the first STA(2) and the second STA(4) to another station by using a capabilities information element of the beacon frame or probe request/response frame and/or an extended capabilities information element.

[49] Referring to FIG. 3, the authentication procedure S20 is performed between the first

STA(2) and the second STA(4). In the authentication procedure S20, an authentication procedure and an encryption method are negotiated among entities which participate in wireless communication. For example, the first STA(2) can perform the authentication procedure S20 with the second STA to be associated with the first STA(2) among one or more APs which are found in the scanning procedure SlO, for example, with an AP. Since a WLAN uses open system authentication method in most cases, the second STA(4) that is an AP performs the authentication procedure without any condition in response to an authentication request from the first STA(2). There are IEEE 802. Ix based Extensible Authentication Protocol-Transport Layer Security (EAP-TLS), Extensible Authentication Protocol-Tunneled Transport Layer Security (EAP-TTLS), Extensible Authentication Protocol-Flexible Authentication via Secure Tunneling (EAP-FAST), Protected Extensible Authentication Protocol (PEAP), and the like, as a stricter authentication method.

[50] When the authentication procedure S20 is successfully performed, the first STA(2) performs the association procedure (S30). The association procedure is an optional procedure performed in a case where the first STA(2) is a non-AP STA, and the second STA(4) is an AP. In the association procedure S30, an identifiable connection, that is, a wireless link is set between the first STA(2) and the second STA(4). For the association procedure S30, the first STA(2) transmits an association request frame to the second STA(4) which successfully completes the authentication procedure S20. The second STA(4) transmits an association response frame with a state value of 'successful' to the first STA(2) in response to the association request frame. The association response frame includes an identifier which identifies association with the first STA(2), for example, an association ID (AID).

[51] Even after the association procedure S30 is successfully completed, in a case where a connection state between the first STA(2) and the second STA(4) deteriorates, the first STA(2) performs an association procedure with another accessible AP. This association procedure is referred to as a reassociation procedure. The reassociation procedure is considerably similar to the aforementioned association procedure S30. More specifically, in the reassociation procedure, the first STA(2) transmits a reassociation request frame to anther AP (an AP which successfully completes the authentication procedure S20 among candidate APs which are found in the aforementioned scanning procedure SlO) that is not currently associated with the first STA(2). The AP transmits a reassociation response frame to the first STA(2). However, the reassociation request frame further includes information on the previously associated AP. The reassociated AP can transmit data buffered in the second STA(4) that is the previous AP to the first STA(2).

[52] Referring to FIG. 3, the radio measurement procedure is performed between the first

STA(2) and the second STA(4) which complete the authentication procedure (S20) or the authentication procedure (S20) and the association procedure (S30) (S40). In FIG. 3, the radio measurement procedure is performed between the first STA(2) and the second STA(4) which complete the association procedure (S30) in the infrastructure BSS. This is only an example.

[53] The first STA(2) and the second STA(4) which performs the radio measurement procedure according to the embodiment of the present invention may be devices which support the IEEE 802.1 In. The IEEE 802.1 In is a wireless LAN protocol suitable to transmit multimedia data as a technical standard for providing a throughput equal to or greater than 100 Mbps. In order to improve the throughput, the IEEE 802.1 In employs various transmission techniques. One of the transmission techniques is an aggregation technique. In aggregation of a frame, medium access control (MAC) layer is extended unlike an existing method of extending a physical layer. The aggregation technique includes an aggregate-MAC service data unit (A-MSDU) and an aggregate-MAC protocol data unit (A-MPDU). In the aggregation technique of a frame, a plurality of frames are aggregated into one and transmitted. Accordingly, it is possible to remove a time for distinguishing frames from one another. In addition, it is possible to effectively transmit frames by reducing an overhead of a header of a physical layer.

[54] The A-MSDU includes a plurality of MSDUs. The A-MPDU includes a plurality of

MPDUs. Since the A-MPDU can individually control transmission of a plurality of packets to be aggregated into a single physical frame, the A-MPDU is valid for aggregation of long packets. Although the A-MSDU cannot individually control transmission of frames, an overhead is small. Accordingly, the A-MSDU is valid for aggregation of short packets.

[55] FIG. 4 is a block diagram illustrating a format of the A-MSDU. Referring to FIG. 4, an A-MSDU 100 is a sequence of a plurality of A-MSDU subframes 110. Each A- MSDU subframe 110 includes a subframe header 102, a MSDU field 104, and a padding field 106. The padding field 106 has a variable length of 0 to 3 octets so that a length of each subframe 110 is a multiple of four octets. The last subframe has no padding unit. The subframe header field 102 includes three subfields, which are a destination address (DA) 102a, a source address (SA) 102b, and a length subfield 102c. The length subfield 102c includes information on a length of the MSDU field 104 in units of octets.

[56] Next, a protocol that is applicable for the radio measurement procedure according to an embodiment of the present invention will be described in detail. The protocol for the radio measurement procedure may be applicable in the radio measurement procedure (S40) of FIG. 3 or in a triggered STA statistics request and report procedure for an A-MSDU or A-MPDU to be described. The triggered STA statistics request and report procedure for the A-MSDU or A-MPDU may be a radio measurement procedure for a triggered A-MSDU or A-MPDU STA counter.

[57] In a wireless network system, an STA can perform a radio measurement procedure for one or more channels or request one or more other STAs belonging to the same BSS or IBSS to perform the radio measurement procedure. In a case where the STA requests other STAs to perform the radio measurement procedure for one or more channels, the requesting STA transmits a radio measurement request frame including one or more measurement request elements to the requested STA. The radio measurement request frame may be transmitted to the requested STA through an individual or group destination address.

[58] In the radio measurement procedure, the requesting STA and the requested STA are members of the same infrastructure BSS or IBSS. A radio measurement request frame with an individual receiving address is transmitted only to an STA in which a radio measurement capability value is set in a previous procedure (the association procedure (S30) of FIG. 3). A measurement request element included in one radio measurement request frame can specify various measurement types over a plurality of channels.

[59] The STA that transmits the radio measurement request for requesting another STA to perform the radio measurement procedure for an operating channel can continuously transmit an A-MSDU and an A-MPDU to still another STA while performing the requested procedure. The STA that transmits the radio measurement request for requesting anther STA to perform the radio measurement procedure for a non- operating channel needs not to do any action so that traffic proceeds to the STA.

[60] The measurement result requested by the radio measurement requesting element is included in one or more measurement report elements corresponding to the request and reported. Each measurement report element transmitted in response to the request has the same measurement token as that included in a corresponding measurement request element. Each measurement result has to be transmitted to the requesting STA without delay. Each radio measurement report frame has the same dialogue token as that of a corresponding radio measurement request frame.

[61] In the triggered STA statistics request and report procedure, a requesting STA transmit can inform a requested STA that the requesting STA desires to receive a triggered autonomous report by transmitting a radio measurement frame including a measurement request elements in which an enable bit and a report bit are l's. A measurement type desired to be included in the triggered autonomous report is included in the measurement type field. A triggered condition for determining when the measurement report is generated is specified in the measurement request field. The measurement request element used to control the triggered autonomous report is included in the radio measurement request frame and transmitted. The measurement request element used to request a measurement procedure may appear in the same radio measurement request frame. This radio measurement request frame may be transmitted to a group receiver address so that an autonomous report triggered by one or more STAs may be available. In a case where the requested triggered condition is not satisfied, the requested STA does not transmit an autonomous report.

[62] The requested STA that receives the radio measurement request frame for requesting the triggered autonomous report from another STA transmits a suitable type of report to an individual address of the requesting STA. That is, in the triggered STA statistics procedure, the requested STA transmits the autonomous report frame to an individual address of a suitable requesting STA. In addition, in a case where a specified condition is satisfied, the requested STA transmits the autonomous report frame to the requesting STA.

[63] In a non-AP STA which is the requested STA which receives the triggered statistics request with respect to various measurement types, a plurality of triggered measurement procedures are concurrently performed with respect to a plurality of requested measurement types. In this case, the triggered measurement procedures are logically independent of one another. A reporting condition such as a triggered timeout period is applied only to a measurement request in which the reporting condition is set.

[64] Next, a radio measurement procedure according to an embodiment of the present invention will be described. The present embodiment is a triggered STA statistics request and report procedure for the A-MPDU or A-MSDU or a triggered A-MSDU or A-MPDU statistics request and report procedure in a wireless network system which supports the IEEE 820.1 In. The triggered STA statistics request and report procedure for the A-MPDU and the A-MSDU is one of radio measurement procedures. In the triggered STA statistics request and report procedure, a report message is transmitted in a case where statistics for the A-MSDU or A-MPDU reaches a threshold specified in the request message.

[65] FIG. 5 is a functional block diagram illustrating a triggered STA statistics request for an aggregate-MAC protocol data unit (A-MPDU) and an A-MSDU in a wireless network system that supports the IEEE 802.1 In according to an embodiment of the present invention. According to the present embodiment, a requesting STA specifies a reporting condition of a reporting STA or requested STA with respect to the A-MSDU or A-MPDU and transmits a request message. The requested STA automatically transmits a report message in a case where the measured statistics data from A-MSDU or A-MPDU counter satisfies the reporting condition. Here, the requesting STA denotes an STA that transmits an STA statistics request frame so as to obtain STA statistics information. A reporting STA, a measuring STA, or a requested STA indicates an STA which transmits the STA statistics report frame including STA statistics information that is gathered in response to the STA statistics request frame to the requesting STA.

[66] Referring to FIG. 5, the requesting STA (for example, the first STA(2) of FIG. 3) transmits a triggered STA statistics request message for the A-MSDU or A-MPDU to the requested STA (for example, the second STA(4) of FIG. 3) (S41). The triggered STA statistics request message for the A-MSDU or A-MPDU is a message for requesting a triggered reporting process from an A-MSDU or A-MPDU counter. The triggered STA statistics request message may be a triggered radio measurement request frame in which measurement request elements are specified as STA statistics request elements. In addition, the triggered STA statistics request message may include a predetermined triggered condition for the A-MSDU or A-MPDU.

[67] According to the present embodiment, the triggered radio measurement request frame is different from a general radio measurement request frame including an STA statistics request element with no triggered reporting subfield in that the STA statistics request element that is the measurement request element included in the triggered radio measurement request frame further includes a triggered reporting subfield. In addition, according to the present embodiment, a statistics group of a triggered condition that is specified in the triggered reporting subfield may be related to an A-MSDU counter or A-MPDU counter, or an STA counter or QoS STA counter. In the latter case, the triggered radio measurement request frame may be referred to a triggered STA statistics request frame or triggered QoS STA statistics request frame, for example.

[68] FIG. 6 is a block diagram illustrating an example of an example of a triggered radio measurement request frame 100 according to an embodiment of the present invention. Referring to FIG. 6, the triggered radio measurement request frame 100 includes a category field 110, an action field 120, a dialog token field 130, a number of repetition field 140, and a measurement request element field 150. Since a measurement type of the triggered radio measurement request frame 100 is an STA statistics request, the measurement request element field 150 includes an STA statistics request element. In addition, a measurement request field 156 of the STA statistics request element additionally includes a triggered reporting subfield 156d. Hereinafter, each element included in the triggered radio measurement request frame 100 will be described in detail.

[69] The category field 110 may be set to a value for indicating a radio measurement category. The action field 120 may be set to a value for indicating a measurement request among radio measurement actions. In addition, the dialog token field 130 is set to a non-zero value that is selected by the requesting STA. The dialog token field 130 may be set to a characteristic value for identifying an exchange of the triggered radio measurement request frame 100 for a radio measurement report frame that is transmitted in response to the triggered radio measurement request frame 100.

[70] The number of repetition field 140 is set to a value for indicating a desired number of repetitions for all the measurement request elements included in the measurement request element field 150 of the triggered radio measurement request frame 100. In a case where the value is zero, a corresponding measurement request element is performed once without repetitions. In a case where the value of the number of repetition field 140 is the maximum value (for example, 65535 in a case where a size of the corresponding field 140 is two bytes) which can be included in the corresponding field 140, the corresponding measurement element is repeatedly performed until the measurement request is canceled or replaced.

[71] The measurement request element field 150 may include no measurement request element, or one or more measurement request elements. In the present embodiment, the triggered STA statistics request frame that is transmitted in the procedure S41 includes one or more measurement elements. The measurement request element field 150 includes requested contents of a statistics element desired to be acquired by the requesting STA from the requested STA or a request for a specific measurement action started by a STA (requested STA) that receives the requested contents. The measurement request element field 150 includes an element ID field 151, a length field 152, a measurement token field 153, a measurement request mode 154, a measurement type field 155, and a measurement request field 156. [72] The element id field 151 is set to a value for indicating a measurement request information element among various information elements. A value that is set in the length field 152 is variable. The value depends on the length of the measurement request field 156. The measurement token field 153 is set to a non-zero value so as to identify one or more measurement request elements which are included in the triggered radio measurement request frame 100 and transmitted. That is, the measurement token field 153 is used to identify an exchange of measurement request elements included in the triggered radio measurement request frame 100 for a measurement report element included in the radio measurement report frame in response to the measurement request element.

[73] The measurement request mode field 154 represents how an STA treats requests for activating or stopping a measurement request and an autonomous report. For example, the measurement request mode field 154 includes information for indicating a type of a measurement request such as information on whether one or more measurement processes start in a parallel manner, information on whether a measurement process is requested, information on whether a measurement request is controlled, and information on a report type for a corresponding measurement request. It is possible to indicate the triggered radio measurement request frame by setting the measurement request mode subfield 154 to a predetermined value.

[74] In general, the measurement type subfield 155 is set to a value for indicating a type of a measurement request or measurement report. In case of the triggered radio measurement request frame 100 for the STA statistics, that is, in a case where a measurement type is the STA statistics request, the measurement type subfield 155 is set to a value for indicating the STA statistics request.

[75] The measurement request subfield 156 includes detailed information on a measurement type specified in the measurement type subfield 155. In case of the triggered radio measurement request frame 100 related to the STA statistics, the measurement request subfield 156 may include a randomization interval subfield 156a, a measurement duration subfield 156b, a group identity subfield 156c, and a triggered reporting subfield 156d.

[76] The randomization interval subfield 156a includes an arbitrarily specified value by using the requesting STA. In a case where there are continuous measurement requests, this value specifies an upper limit of a starting time of a measurement process of a corresponding measurement request. In general, the measurement duration subfield 156b is set to a value for indicating a time interval of a measurement process of a corresponding request. In case of a triggered radio measurement request related to the STA statistics according to the embodiment, the measurement duration subfield 156d may be set to zero. [77] Then, the group identity subfield 156c is set to a value for indicating a requested statistics group. According to the embodiment of the present invention, the group identity subfield 156c may be set to a value for indicating a statistics group related to an A-MSDU or A-MPDU (for example, an A-MSDU or A-MPDU) of a countergroup3).

[78] The triggered reporting subfield 156d is used to specify a condition for triggering a report from the requested STA, a value of a triggered timeout, thresholds of measurement items for each measurement group of an STA statistics request. In general, it is optional whether the triggered reporting subfield 156d exists or not. In the present embodiment, in case of the triggered radio measurement request frame in which a statistics group specifies a reporting condition with respect to an STA counter that is an A-MSDU or A-MPDU, the measurement request field 156 necessarily includes the triggered reporting subfield 156d.

[79] Case in which a triggered reporting process from an A-MSDU counter is requested

[80] FIG. 7 is a block diagram illustrating an example of a format of a triggered reporting subfield 156d in a case where the triggered radio measurement request frame 100 has relation to an STA counter for an A-MSDU or A-MSDU counter. That is, the triggered reporting subfield 156d with the format of FIG. 7 represents a case where the group identity subfield 156c of the triggered radio measurement request frame 100 of FIG. 6 is set to a value for indicating the A-MSDU statistics group. A field indicated by 'optional' in FIG. 7 exists only in a case where a bit corresponding to an A-MSDU STA counter trigger condition field 210 is set to a value of '1'.

[81] Referring to FIG. 7, the triggered reporting subfield 156d includes an A-MSDU STA counter trigger condition field 210, a measurement count field 215, and a trigger timeout field 216. In addition, the triggered reporting subfield 156d may include one or more subfields among an A-MSDU failed threshold field (dotl lAMSDUFailedThreshold) 211, an A-MSDU retry threshold field (dotl lAMSDURetryThreshold) 212, an A-MSDU multiple retry threshold field (dotl lAMSDUMultipleRetryThreshold) 213, and an A-MSDU acknowledgement failure threshold field (dotl lAMSDUACKFailureThreshold) 214.

[82] The A-MSDU STA counter trigger condition field 210 is used to specify a condition for triggering a reporting process in a case where a triggered radio measurement reporting process for STA statistics of the A-MSDU is requested. The A-MSDU STA counter trigger condition field 210 may include a plurality of bit-fields. An example of a format of the plurality of bit-fields is shown in FIG. 8. Referring to FIG. 8, the A- MSDU STA counter trigger condition field 210 includes an A-MSDU failed bit (dotl lAMSDUFailed) BO, an A-MSDU retry bit (dotl lAMSDURetry) Bl, an A- MSDU multiple retry bit (dotl 1 AMSDUMultipleRetry) B2, and an A-MSDU ACK failure bit (dotl 1 AMSDUACKFailure) B3. The aforementioned bits may be set to '0' or '1'. For example, when a bit is set to O', it is unnecessary to report a corresponding trigger condition. On the contrary, when a bit is set to ' 1 ' , a reporting process of a corresponding trigger condition is requested.

[83] Accordingly, when a corresponding bit of the A-MSDU STA counter trigger condition field 210 is set to '1', the STA statistics report frame is requested to be transmitted in a case where a value of the STA counter of the A-MSDU is greater than thresholds of corresponding subfields 211 to 214. The value of the STA counter of the A-MSDU is measured within the total number of A-MSDUs that is determined in the measurement count field 215.

[84] The requesting STA which desires to receive a triggered report on measurement statistics of the STA counter for the A-MSDU can set one or more bits (at least one of BO to B3) corresponding to a condition to '1' in the A-MSDU STA counter trigger condition field 210 of FIG. 8 and specify a predetermined threshold in a threshold subfield for an STA counter item corresponding to a bit that is set to ' 1 ' in the A- MSDU STA counter trigger condition field 210 in threshold subfields 211 to 214 for STA counter items of the triggered reporting subfield 156d shown in FIG. 7.

[85] Referring to FIG. 7, the measurement count field 215 includes information for representing the number of A-MSDUs used for determining whether measured statistics on the A-MSDU is equal to or greater than the set threshold. In addition, the trigger timeout field 216 includes information for representing a time for which the measurement STA does not generate an additional STA statistics measurement report after the trigger condition is satisfied.

[86] The failed threshold field 211 includes a value for representing the number of A-

MSDUs to be used as a threshold for a failure condition. The failed threshold field 211 exists only in a case where a failed bit (dotl 1 AMSDUFailed) of the A-MSDU STA counter trigger condition field 210 is set to '1'. The retry threshold field 212 includes a value for representing the number of A-MSDUs to be used as a threshold for a retry condition. The retry threshold field 212 exists only in a case where a retry bit (dotl lAMSDURetry) of the A-MSDU STA counter trigger condition field 210 is set to '1'. The multiple retry threshold field 213 includes a value for representing the number of A-MSDUs to be used as a threshold for a multiple retry condition. The multiple retry threshold field 213 exists only in a case where a multiple retry bit (dotl 1 AMSDUMultipleRetry) of the A-MSDU STA counter trigger condition field 210 is set to '1'. In addition, the ACK failure threshold field 214 includes a value for representing the number of A-MSDU to be used as a threshold for an ACK failure condition. The ACK failure threshold field 214 exists only in a case an ACK failure bit (dotl 1 AMSDUACKFailure) of the A-MSDU STA counter trigger condition field 210 is set to '1'.

[87] Case in which a triggered reporting process from an A-MPDU counter is requested

[88] FIG. 9 is a block diagram illustrating an example of a format of a triggered reporting subfield 156d in a case where the triggered radio measurement request frame 100 of FIG. 6 relates to an STA counter for the A-MPDU or A-MPDU counter. That is, the triggered reporting subfield 156d with the format of FIG. 9 represents a case where the group identity subfield 156c of the triggered radio measurement request frame 100 of FIG. 6 is set to a value for indicating the A-MPDU statistics group. A field indicated by 'optional' in FIG. 9 exists only in a case where a bit corresponding to an A-MSDU STA counter trigger condition field 220 is set to a value of '1'.

[89] Referring to FIG. 9, the triggered reporting subfield 156d includes an A-MSDU STA counter trigger condition field 220, a measurement count field 225, and a trigger timeout field 226. In addition, the triggered reporting subfield 156d may include one or more subfields among a received A-MPDU count threshold field (dotl lAMPDUReceivedCountThreshold) 221, an MPDU count threshold field of a received A-MPDU (dotl IMPDUInReceivedCountThreshold) 222, a received octet count threshold field of an A-MPDU dotl lReceivedOctetsInAMPDUCountThreshold) 223, and an A-MPDU delimiter CRC error count threshold field (dotl 1 AMPDUDelimiterCRCErrorCountThreshold, 224).

[90] The A-MSDU STA counter trigger condition field 220 is used to specify a condition for triggering a reporting process in a case where a triggered radio measurement reporting process for STA statistics of the A-MSDU is requested. The A-MSDU STA counter trigger condition field 220 may include a plurality of bit- fields. An example of a format of the plurality of bit-fields is shown in FIG. 10. Referring to FIG. 10, the A- MSDU STA counter trigger condition field 220 includes a received A-MPDU count bit (dotl 1 AMPDUReceivedCount) BO, an MPDU count bit of a received A-MPDU (dotl IMPDUInReceivedCount) Bl, a received octet count bit of an A-MPDU (dotl lReceivedOctetsInAMPDUCount) B2, and an A-MPDU delimiter CRC error count bit (dotl 1 AMPDUDelimiterCRCErrorCount) B3. The aforementioned bits may be set to '0' or '1'. For example, when a bit is set to O', it is unnecessary to report a corresponding trigger condition. On the contrary, when a bit is set to ' 1 ' , a reporting process of a corresponding trigger condition is requested.

[91] Accordingly, when a corresponding bit of the A-MSDU STA counter trigger condition field 220 is set to '1', the STA statistics report frame is requested to be transmitted in a case where a value of the STA counter of the A-MSDU is greater than thresholds of corresponding subfields 221 to 224. The value of the STA counter of the A-MSDU is measured within the total number of A-MSDUs that is determined in the measurement count field 225. [92] The requesting STA which desires to receive a triggered report on measurement statistics of the STA counter for the A-MSDU can set one or more bits (at least one of BO to B3) corresponding to a condition to '1' in the A-MSDU STA counter trigger condition field 220 of FIG. 10 and specify a predetermined threshold in a threshold subfield for an STA counter item corresponding to a bit that is set to ' 1 ' in the A- MSDU STA counter trigger condition field 210 in threshold subfields 221 to 224 for STA counter items of the triggered reporting subfield 156d shown in FIG. 9.

[93] Referring to FIG. 9, the measurement count field 225 includes information for representing the number of A-MSDUs used for determining whether measured statistics on the A-MSDU is equal to or greater than the set threshold. In addition, the trigger timeout field 226 includes information for representing a time for which the measurement STA does not generate an additional STA statistics measurement report after the trigger condition is satisfied.

[94] The received A-MPDU count threshold field 221 includes a value for representing the number of A-MPDUs to be used as a threshold for the received A-MPDU counter condition. The A-MPDU count threshold field 221 exists only in a case where the received A-MPDU count bit (dotl 1 AMPDUReceivedCount) of the A-MPDU STA counter trigger condition subfield 210 is set to '1'. The MPDU count threshold field

222 of the received A-MPDU includes a value for representing the number of MPDUs to be used as a threshold for the count condition of the MPDU included in the received A-MPDU. The MPDU count threshold field 222 of the received A-MPDU exists only in a case where the MPDU count bit (dotl IMPDUInReceivedAMPDUCount) of the MPDU count of the A-MPDU of the A-MPDU STA counter trigger condition field 220 is set to '1'. The received octet count threshold field 223 of the A-MPDU includes a value for representing the number of octets to be used as a threshold for an octet condition included in the received A-MPDU. The received octet count threshold field

223 of the A-MPDU exists only in a case where the received octet count bit

(dotl lreceivedoctetsInAMpDUCount) of the A-MPDU of the A-MPDU STA counter trigger condition field is set to '1'. In addition, the A-MPDU delimiter CRC error count threshold field 224 includes a value for representing the number of A-MPDUs to be used as a threshold for an A-MPDU delimiter CRC error condition. This A-MPDU delimiter CRC error count threshold field 224 exists only in a case where the A-MPDU delimiter CRC error count bit (dotl 1 AMPDUDelimiterCRCErrorCount) of the A- MPDU STA counter trigger condition field 220 is set to '1'.

[95] In the present embodiment, a format of the triggered STA statistics request frame related to the STA counter for the A-MSDU and the A-MPDU will be defined in detail. It is possible that the requesting STA requests the reporting STA to provide statistics by specifying one or more trigger conditions for each measurement element that is classified according to an STA counter. According to the embodiment, it is possible to perform a more concrete and systematic triggered STA statistics request and report procedure in relation to the STA counter for the A-MSDU or A-MPDU in a wireless network which supports the IEEE 802. Hn.

[96] Returning to FIG. 5, the requested STA that receives the STA statistics request message for the A-MSDU or A-MPDU including the triggered reporting subfield, for example, the triggered radio measurement request frame 100 performs a measurement process with respect to a statistics element specified in the triggered reporting subfield 156d of the frame 100, that is, the requested statistics. This measurement process is performed in a case where the requested STA accepts the triggered STA statistics measurement. The accepted triggered STA statistics measurement request is valid until the request STA is disassociated or successfully reassociated. A measurement process of the requested STA is performed within the number of A-MSDUs or A-MPDUs included in the measurement count field 215 or 225 of the triggered reporting subfield 156d.

[97] As a result of the measurement process, in a case where the trigger condition is satisfied, the requested STA transmits the STA statistics measurement report message to the requesting STA (S43). The STA statistics measurement report message may be a frame including the STA statistics report elements as the measurement report elements. In this case, the STA statistics report message may be a radio measurement report frame. The requested STA or measurement STA, which transmits the STA statistics report message according to the same triggered STA statistics request message, does not additionally transmit an STA statistics report message until the triggered timeout period of the triggered STA statistics request message is expired or until a new trigger condition is satisfied.

[98] In a case where another STA statistics measurement request is received while a measurement process is being performed according to the triggered STA statistics measurement request, the process according to the triggered STA statistics measurement request in progress is stopped for the duration of anther STA statistics measurement request. When the triggered STA statistics measurement request restarts, the previously counted statistics are reset.

[99] The STA statistics data included in the STA statistics report that is transmitted in the procedure (S43) is a value that is accumulated in a plurality of transmitted or received A-MSDU or A-MPDU. The measurement duration is not used in the triggered STA statistics measurement and report. The measurement duration included in the triggered measurement request frame and the triggered measurement report frame may become O'.

[100] All the triggered STA statistics measurement procedures started by the requested STA or measurement STA are terminated when a STA statistics request message in which an enable bit is set to '1' and a report bit is set to '0' is received. In addition, an STA that transmits the triggered STA statistics request message can update a trigger condition by transmitting a new triggered STA statistics request message for specifying a new trigger condition.

[101] FIG. 11 is a block diagram illustrating an example of a format of the triggered STA statistics report message that is transmitted in the procedure (S43) by the requested STA, which receives the triggered STA statistics request message including the triggered reporting field of FIG. 7 in the procedure (S41). A message format of FIG. 11 represents a case where an action frame body format is used.

[102] Referring to FIG. 11, a triggered STA statistics report frame 300 includes a category field 310, an action field 320, a dialog token field 330, and a measurement report element field 340. Like the triggered STA statistics request frame 100 of FIG. 6, the category field 310 is set to a value for indicating a radio measurement category. The action field 320 is set to a value for indicating a measurement report. In addition, the dialog token field 330 is set to the same value as the dialog token field 130 of the triggered STA statistics request frame 100. Accordingly, the requesting STA can recognize which request frame the received report frame 300 responds to.

[103] The measurement report element field 340 includes one or more measurement report elements. The measurement report elements that is gathered by the requested STA includes a measurement report for a request element of which trigger condition included in the trigger STA statistics request frame 100 is satisfied. The measurement request element field 340 includes an element ID subfield 341, a length subfield 342, a measurement token subfield 343, a measurement report mode subfield 344, a measurement type subfield 345 and a measurement report subfield 346.

[104] The element ID subfield 341 is set to a value for indicating a measurement report element. A value that is set in the length subfield 342 is variable. The value depends on the length of the measurement report subfield 346. The measurement token subfield 343 is set to a non-zero characteristic value among the measurement report elements of a corresponding triggered STA statistics report frame 300. The measurement report mode subfield 344 is used to indicate a concrete reason (delay, impossibility, rejection, and the like) of a failed or rejected measurement request. The measurement report mode subfield 344 consists of one or more bit fields. The measurement type subfield 345 is set to a value for identifying a measurement report element field 340. In the present embodiment, the measurement type subfield 345 may be set to a value for indicating an STA statistics report.

[105] The measurement report subfield 346 includes detailed measurement contents about a measurement type indicated by the measurement type subfield 345. The triggered STA statistics report frame 300 may include detailed contents related to a gathered or measured STA statistics result. For example, the measurement report subfield 346 is used to report a change in requested statistics group data that is measured for the measurement duration. In a case where the measurement duration is zero, the measurement report subfield 346 reports a current value instead of a change in statistics group data. This measurement request subfield 346 may include a measurement duration unit 346a, a group identity unit 346b, a statistics group data unit 346c, and a reporting reason unit 346d.

[106] The measurement duration unit 346a is set to a value for indicating a time interval taken to obtain a value that is measured and included in the statistics group data unit 346c. In general, the value is a time interval for which a change in statistics group data occurs. However, in case of the triggered STA statistics report frame, or in a case where a current statistics group data is reported, the measurement duration unit 346a may be set to O'. In addition, in case of a triggered reporting process, the measurement duration unit 346a may be set a predetermined value, for example, '65535'.

[107] Then, the group identity unit 346b is set to a value for indicating a requested statistics group which describes statistics data included in the statistics group data unit 346c. According to the present embodiment, the group identity unit 346b may be specified as a value for indicating STA statistics for the A-MSDU or A-MPDU. The reporting reason unit 346d is a bit field for indicating a reason for which the reporting STA transmits a corresponding triggered STA statistics report frame 300. This reporting reason unit 346d is an optional field which exists only in a case where a statistics group name indicated by the group identity unit 346b has relation to a non-STA counter, a QoS counter, or an RSNA counter.

[108] Case of a triggered reporting process from an A-MSDU counter

[109] FIG. 12 is a block diagram illustrating a format of a measurement request field for an STA counter of an A-MSDU. The measurement request field with the format of FIG. 12 may be included in the statistics group data unit 346c of FIG. 11. Referring to FIG. 12, the measurement request field includes a transmitted A-MSDU count field (dotl lTransmittedAMSDUCount), a failed A-MSDU count field (dotl lFailedAMSDUCount), a retry A-MSDU count field (dotl 1 Retry AMSDUCount), multiple retry A-MSDU count field (doolMultipleRetryAMSDUCount), a transmitted octet field of an A-MSDU count (dotl lTransmittedOctetsInAMSDUCount), an A-MSDU ACK failure count field (dotl 1 AMSDUAAckFailureCount), a received A-MSDU count (dotl IReceivedAMSDUCount), and a received octet field of an A-MSDU count (dot 11 ReceivedOctetsInAMSDUCount) .

[110] FIG. 13 is a block diagram illustrating a format of a reporting reason field for an STA counter of an A-MSDU. A reporting reason field with a format of FIG. 13 may be included in the reporting reason unit 346d of FIG. 11. Referring to FIG. 13, the reporting reason field includes an A-MSDU failed bit (dotl 1 AMSDUFailed), an A- MSDU retry bit (dotl 1 AMSDURetry), an A-MSDU multiple retry bit (dotl 1 AMSDUMultipleRetry), and an A-MSDU ACK failure bit (dotl 1 AMSDUAC KFailure). The aforementioned bits may be set to '0' or ' 1 ' . For example, when a bit is set to O', reporting data for a corresponding trigger condition is not included in the reporting reason field. On the contrary, when a bit is set to ' 1 ' , reporting data for a corresponding trigger condition is included in the reporting reason field.

[I l l] Case of a triggered reporting process from an A-MPDU counter

[112] FIG. 14 is a block diagram illustrating a format of a measurement request field for an STA counter of an A-MPDU. A measurement request field with the format of FIG. 14 may be included in the statistics group data unit 346c of FIG. 11. Referring to FIG. 14, the measurement request field includes a transmitted A-MPDU count field (dotl lTransmittedAMPDUCount), a transmitted MPDU count field of the A-MPDU (dotl lTransmittedMPDUsInAMPDUCount), a transmitted octet count field of the A- MPDU (dotl ITransmittedOctetsInAMPDUCount), a received A-MPDU count field (dotl 1 AMPDUreceivedCount), an MPDU count field of a received A-MPDU (dotl IMPDUInreceivedAMPDUCount) received octet count field of the A-MPDU (dotl lReceivedOctetsInAMPDUCount), and an A-MPDU delmiter CRC error count field (dotl 1 AMPDUDelimiterCRCErrorCount)

[113] FIG. 15 is a block diagram illustrating a format of a reporting reason field for an STA counter of an A-MPDU. A reporting reason field with the format of FIG. 15 may be included in the reporting reason unit 346d of FIG. 11. Referring to FIG. 15, the reporting reason field includes a received A-MPDU count bit (dotl 1 AMPDUReceivedCount) BO, an MPDU count bit of a received A-MPDU (dotl IMPDUInReceivedCount) Bl, a received octet count bit of an A-MPDU (dotl lReceivedOctetsInAMPDUCount) B2, and an A-MPDU delimiter CRC error count bit (dotl 1 AMPDUDelimiterCRCErrorCount) B3. The aforementioned bits may be set to '0' or '1'. For example, when a bit is set to O', reporting data for a corresponding trigger condition is not included in the reporting reason field. On the contrary, when a bit is set to ' 1 ' , reporting data for a corresponding trigger condition is included in the reporting reason field.

[114] As described above, in a WLAN system that supports the IEEE 802.1 In, it is possible to transmit multimedia data such as voices or images by aggregating the multimedia data through the A-MSDU and the A-MPDU. This is based on that the IEEE 802. Hn supports the IEEE 802. l ie standard. Accordingly, it is necessary to apply a QoS statistics request and report procedure for each traffic ID (TID) to an aggregation frame such as an A-MSDU or A-MPDU.

[115] For this, a terminal that transmits and receives the A-MSDU or A-MPDU may manage an STA counter and a QoS STA counter through the following method, in addition to the aforementioned counter for STA statistics of the A-MSDU or A- MPDU.

[116] According to the IEEE 802.1 In, the A-MSDU is allowed to be aggregated only for the MSDUs of which TID values are equal. Accordingly, in a case where the A-MSDU is transmitted and received, a QoS STA counters from dotl lQoSCounters Group also updates a management information base (MIB) value with respect to the TID value of the A-MSDU together with the aforementioned STA counters from dotl lCountersGroup3 (A-MSDU). For example, in a case where an A-MSDU ACK frame is not received after an A-MSDU corresponding to AC_V0 is transmitted, a dotl lQoSACKFailureCount for the AC_V0 may increase by one, in addition to a counter for dotl 1 AMSDU ACKFailure.

[117] According to the IEEE 802.1 In, MPDUs which constitute the A-MPDU are MSDUs or A-MSDUs. Accordingly, in a case where the A-MPDU is transmitted and received, a corresponding STA counter also updates a MIB value with respect to MPDUs which constitute the A-MPDU together with the aforementioned STA counters from dotl lCountersGroup3 (A-MSDU). For example, in a case where an A-MPDU ACK frame is not received after an A-MPDU that consists of MSDUs corresponding to AC - VO, a counter for dotl lQoSACKFailureCount for the AC_V0 may increase by one, in addition to a counter for dotl 1 AMPDUACKFailure.

[118] In a radio measurement procedure according to an embodiment of the present invention, it is possible to apply a QoS statistics request and report procedure or a triggered QoS statistics request and report procedure to MSDUs that constitute an A- MSDU or A-MPDU. According to an embodiment of the present invention, in an STA counter statistics request and report procedure for the A-MSDU or A-MPDU, if the (triggered) radio measurement procedure is applied to frames that constitute a transmitted or received A-MSDU or A-MPDU, it is possible to acquire accurate statistics data. Thus, it is possible to efficiently manage a wireless network.

[119] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims. Industrial Applicability

[120] The present invention relates to a networking process related to wireless com- munication technology, a communication protocol, and a communication procedure in a wireless communication system. The present invention may be used to establish a wireless communication system and to manufacture equipments and terminals which constitute the wireless communication system. Specifically, the present invention can be applied to a network management protocol in a wireless communication system.

Claims

[1] A radio measurement procedure for measuring station statistics in a wireless local area network (WLAN), comprising: transmitting a triggered station statistics request message, which includes trigger conditions and requests a triggered reporting process from an aggregate-MAC service data unit (A-MSDU) counter, to a requested station; and receiving a station statistics report message including requested statistics information from the requested station in a case where the trigger conditions occur in the A-MSDU counter.

[2] The radio measurement procedure of claim 1, wherein the triggered station statistics request message includes: a group identity field for indicating a requested A-MSDU statistics group; and a triggered reporting field for the A-MSDU counters used to specify the trigger conditions, and wherein the trigger conditions include reporting triggers and an A-MSDU count threshold for a corresponding reporting trigger.

[3] The radio measurement procedure of claim 2, wherein the triggered reporting field for the A-MSDU counter includes: an A-MSDU counter trigger condition subfield including a plurality of bit fields for specifying the reporting triggers; and one or more A-MSDU count threshold subfields for specifying a value for representing the number of A-MSDUs which is used as a threshold for a corresponding reporting trigger, and wherein each of the one or more A-MSDU count threshold subfields exists only in a case where a corresponding bit field in the A-MSDU counter trigger condition subfield is set to '1'.

[4] The radio measurement procedure of claim 3, wherein the A-MSDU counter trigger condition subfield includes one or more bit fields which are set to Ts among an A-MSDU failed bit field (dotl 1 AMSDUFailed), an A-MSDU retry bit field (dotl 1 AMSDURetry), an A-MSDU multiple retry bit field (dotl 1 AMSDUMultipleRetry), and an A-MSDU ACK failure bit field (dotl 1 AMSDUACKFailure).

[5] The radio measurement procedure of claim 3, wherein the A-MSDU count threshold subfield includes one or more subfields among an A-MSDU failed threshold field (dotl lAMSDUFailedThreshold), an A-MSDU retry threshold field (dotl 1 AMSDURetryThreshold), an A-MSDU multiple retry threshold field (dotl lAMSDUMultipleRetryThreshold), and an A-MSDU ACK failure threshold field (dotl 1 AMSDUACKFailureThreshold), which are set to predetermined values.

[6] The radio measurement procedure of claim 3, wherein the triggered reporting field for the A-MSDU counter further includes: a measurement count subfield which is set to a value for indicating the number of A-MSDUs that is used to determine whether a measured A-MSDU station statistics value is greater than a value specified in a corresponding A-MSDU threshold field; and a trigger timeout subfield which is set to value for indicating a period for which the requested station does not generate an additional station statistics report message after the trigger condition is satisfied.

[7] The radio measurement procedure of claim 2, wherein the group identity field and the triggered reporting field for the A- MSDU counters are included in a measurement request field of a measurement request element of the triggered station statistics request message, and wherein the measurement request element further includes a measurement type field which is set to a value for indicating an A-MSDU station statistics request.

[8] The radio measurement procedure of claim 7, wherein the measurement request field further includes a duration field that is set to O'.

[9] A radio measurement procedure for measuring station statistics in a wireless local area network (WLAN), comprising: transmitting a triggered station statistics request message, which includes trigger conditions and requests a triggered reporting process from an aggregate-MAC protocol data unit (A-MPDU) counter, to a requested station; and receiving a station statistics report message including requested statistics information from the requested station in a case where the trigger conditions occur in the A-MPDU counter.

[10] The radio measurement procedure of claim 9, wherein the triggered station statistics request message includes: a group identity field for indicating a requested A-MPDU statistics group; and a triggered reporting field for the A-MPDU counters used to specify the trigger conditions, and wherein the trigger conditions include reporting triggers and an A-MPDU count threshold for a corresponding reporting trigger.

[11] A radio measurement procedure for measuring station statistics in a wireless local area network (WLAN), comprising: receiving a triggered station statistics request message, which includes trigger conditions and requests a triggered reporting process from an aggregate-MAC service data unit (A-MSDU) or an aggregate-MAC protocol data unit (A-MPDU) counter, from a requesting station; measuring requested A-MSDU or A-MPDU station statistics; and transmitting a station statistics report message including measured A-MSDU or

A-MPDU station statistics information to the requesting station in a case where the trigger conditions occur in the A-MSDU or A-MPDU counter as a result of measurement.

[12] The radio measurement procedure of claim 11 , wherein the triggered station statistics request message includes: a group identity field for indicating a requested A-MSDU or A-MPDU statistics group; and a triggered reporting field for the A-MSDU or A-MPDU counters used to specify the trigger conditions, and wherein the trigger conditions include reporting triggers and an A-MSDU or A-

MPDU count threshold for a corresponding reporting trigger.

[13] The radio measurement procedure of claim 12, wherein the station statistics report message is a radio measurement report frame including a measurement report element, wherein the measurement report element includes a measurement type field and a measurement report field, which are set to a value for indicating a A-MSDU or

A-MPDU station statistics report, and wherein the measurement report field includes a reporting reason subfield that is a bit field for indicating a reason for transmitting the station statistics report message.

[14] A wireless device for supporting the radio measurement procedure of claim 1.

[15] A wireless device for supporting the radio measurement procedure of claim 11.