Wireless communication method using fragmentation and wireless communication terminal using the same

Abstract

To provide, in one embodiment, a wireless communication terminal using fragmentation.SOLUTION: Disclosed herein is a wireless communication terminal that is a transmitter to transmit data. The wireless communication terminal includes a transceiver and a processor. The processor uses the transceiver to transmit, to a recipient, first information on a fragmentation level to be used for data to be transmitted to the recipient, in an add block ACK (ADDBA) setup procedure.SELECTED DRAWING: Figure 22

Description

[Technical field]

[0001] The present invention relates to a wireless communication method and a wireless communication terminal that utilizes fragmentation. [Background technology]

[0002] Recently, as the use of mobile devices has become more widespread, wireless LAN technology that provides high-speed wireless Internet services to these devices has been gaining attention. Wireless LAN technology is a technology that uses short-range wireless communication technology to wirelessly connect mobile devices such as smartphones, smart pads, laptop computers, portable multimedia players, embedded devices, etc. to the Internet at home, in a business, or in a specific service area.

[0003] Since IEEE (Institute of Electrical and Electronics Engineers) 802.11 supported early wireless LAN technology using 2.4GHz frequency, it has put into practical use or is currently developing various technology standards. First, IEEE 802.11b supports a maximum communication speed of 11Mbps using 2.4GHz frequency band. IEEE 802.11a, which was commercialized after IEEE 802.11b, uses 5GHz frequency band instead of 2.4GHz band, reducing the impact of interference compared to the considerably congested 2.4GHz frequency band, and improves communication speed to a maximum of 54Mbps using OFDM technology. However, IEEE 802.11a has the disadvantage of a shorter communication distance compared to IEEE 802.11b. IEEE 802.11g has attracted considerable attention because it uses the 2.4GHz frequency band like IEEE 802.11b to achieve a maximum communication speed of 54Mbps and satisfies backward compatibility, but it also has an advantage over IEEE 802.11a in communication distance.

[0004] IEEE 802.11n is a technical standard established to overcome the communication speed limitations that have been pointed out as a weakness of wireless LAN. The purpose of IEEE 802.11n is to increase the network speed and reliability and extend the operating distance of wireless networks. More specifically, IEEE 802.11n supports high throughput (HT) with a data processing speed of up to 540 Mbps and is based on MIMO (Multiple Inputs and Multiple Outputs) technology that uses multiple antennas on both the transmitting and receiving ends to minimize transmission errors and optimize data speed. This standard also uses a coding method that transmits multiple duplicate copies to increase data reliability.

[0005] As the use of wireless LANs has become more widespread and applications using them have become more diverse, a new wireless LAN system is required to support a data processing rate (Very High Throughput, VHT) higher than that supported by IEEE 802.11n. Among these, IEEE 802.11ac supports a wide bandwidth (80MHz~160MHz) at 5GHz frequency. Although the IEEE 802.11ac standard was defined only in the 5GHz band, early 11ac chipsets also support operation in the 2.4GHz band for backward compatibility with existing 2.4GHz band products. Theoretically, this standard allows for a multi-station wireless LAN speed of at least 1Gbps and a maximum single link speed of at least 500Mbps. This is done by extending the wireless interface concept accepted by 801.11n, such as wider radio frequency bandwidth (up to 160MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high density modulation (up to 256QAM). Also, there is IEEE 802.11ad, a method of transmitting data using the 60GHz band instead of the conventional 2.4GHz / 5GHz. IEEE 802.11ad is a transmission standard that uses beamforming technology to provide speeds of up to 7Gbps, and is suitable for streaming large amounts of data and high bitrate videos such as uncompressed HD video. However, the 60GHz frequency band has the disadvantage that it is difficult to pass through obstacles and can only be used between devices in close proximity.

[0006] Meanwhile, discussions are currently underway to provide high-efficiency and high-performance wireless LAN communication technology in high-density environments as the standard for next-generation wireless LANs after 801.11ac and 802.11ad. In other words, next-generation wireless LAN environments should provide high-frequency-efficient communication both indoors and outdoors in the presence of high-density stations and APs (Access Points), and various technologies are required to realize this.

[0007] In particular, as the number of devices using wireless LAN increases, it becomes necessary to use the designated channels efficiently. Therefore, there is a demand for technology that uses the bandwidth efficiently by enabling data transmission between multiple stations and APs simultaneously. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of one embodiment of the present invention is to provide a wireless communication terminal that uses fragmentation. [Means for solving the problem]

[0009] According to an embodiment of the present invention, a wireless communication terminal as a transmitter of data includes a transceiver unit and a processor, and the processor transmits, to a receiver, first information regarding a fragmentation level to be used for data to be transmitted to the receiver in an add block ACK (ADDBA) setup procedure, using the transceiver unit.

[0010] The first information relates to a fragmentation level to be used when transmitting data corresponding to a particular TID to the recipient.

[0011] The processor receives second information from the receiver using the transceiver unit and determines a fragmentation level of data corresponding to the particular TID based on the second information, the second information being information regarding a fragmentation level of fragments that the receiver may receive when receiving data corresponding to the particular TID.

[0012] The processor fragments the data corresponding to the particular TID to a fragmentation level that is equal to or lower than the fragmentation level indicated by the second information.

[0013] The processor inserts first information into an ADDBA request frame and transmits the ADDBA request frame to the recipient.

[0014] According to an embodiment of the present invention, a wireless communication terminal that is a recipient of data includes a transceiver unit and a processor, the processor receives first information from a transmitter that intends to transmit data using the transceiver unit, the first information being information regarding a fragmentation level that the transmitter intends to use for data to be transmitted to the wireless communication terminal.

[0015] The first information is information regarding a fragmentation level that the transmitter intends to use when transmitting data corresponding to a specific TID to the wireless communication terminal.

[0016] The processor transmits second information to the transmitter using the transceiver unit, and the second information is information regarding a fragmentation level of fragments that the wireless communication terminal can receive when the wireless communication terminal receives data corresponding to the specific TID.

[0017] The processor receives an ADDBA request frame from the transmitter and obtains first information from the ADDBA request frame.

[0018] The processor inserts second information into the ADDBA response frame and transmits the ADDBA response frame to the transmitter, the second information being information regarding a fragmentation level of fragments that the wireless communication terminal can receive.

[0019] The processor receives data from the transmitter using the transceiver, selects a format of a Block ACK frame based on the first information, and transmits a Block ACK frame for the data received from the transmitter according to the format of the Block ACK frame.

[0020] The processor selects a format of a Block ACK frame based on the first information.

[0021] The data is transmitted via A-MPDU, the A-MPDU including at least one fragment, and if the fragment numbers of the at least one fragment are all 0, the processor transmits a Block ACK frame including a bitmap in which each bit indicates whether or not each MSDU (MAC Service Data Unit) is received.

[0022] The data is transmitted via an A-MPDU, and when the processor receives all MPDUs contained in the A-MPDU, the processor transmits a Block ACK frame including a bitmap in which each bit indicates whether each MSDU has been received.

[0023] An operating method of a wireless communication terminal that is a transmitter transmitting data according to an embodiment of the present invention includes a step of inserting first information regarding a fragmentation level to be used for data to be transmitted to a receiver into an ADDBA request frame, and a step of transmitting the ADDBA request frame to the receiver.

[0024] The first information relates to a fragmentation level to be used when transmitting data corresponding to a particular TID to the recipient.

[0025] The method further includes receiving an ADDBA response frame from the receiver using the transceiver unit, acquiring second information from the ADDBA response frame, and determining a fragmentation level of data corresponding to the specific TID based on the second information, the second information being information regarding a fragmentation level of fragments that the receiver may receive when the receiver receives data corresponding to the specific TID.

[0026] The step of determining a fragmentation level of the data corresponding to the specific TID includes the step of determining a fragmentation level of the data corresponding to the specific TID to a fragmentation level that is equal to or lower than the fragmentation level indicated by the second information.

[0027] The size of the Buffer Size field value of the ADDBA request frame implicitly indicates the first information, and the Buffer Size field indicates information regarding the size of a buffer required for the data transmission. Effect of the Invention

[0028] One embodiment of the present invention provides a communication method using fragmentation and a wireless communication terminal using the same. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram showing a wireless LAN system according to an embodiment of the present invention. [Diagram 2] FIG. 11 is a diagram showing a wireless LAN system according to another embodiment of the present invention. [Diagram 3] FIG. 2 is a block diagram showing a configuration of a station according to an embodiment of the present invention. [Figure 4] 2 is a block diagram showing a configuration of an access point according to an embodiment of the present invention. FIG. [Diagram 5] 2 is a diagram illustrating a process in which a station sets up a link with an access point according to one embodiment of the present invention. [Figure 6] A diagram showing a method for transmitting information regarding fragmentation level using ADDBA according to an embodiment of the present invention. [Figure 7] A diagram showing the format of an ADDBA request frame and an ADDBA response frame for signaling information regarding fragmentation levels according to another embodiment of the present invention. [Figure 8]A diagram showing a MAC frame format for signaling information regarding fragmentation levels according to yet another embodiment of the present invention. [Figure 9] A diagram showing the formats of an ADDBA response frame and an ADDBA request frame for signaling information regarding fragmentation levels according to yet another embodiment of the present invention. [Figure 10] A diagram showing the formats of an ADDBA response frame and an ADDBA request frame for signaling information regarding fragmentation levels according to yet another embodiment of the present invention. [Figure 11] A diagram showing a trigger frame format for signaling information regarding fragmentation levels according to yet another embodiment of the present invention. [Figure 12] A diagram showing a trigger frame format for signaling information regarding fragmentation levels according to yet another embodiment of the present invention. [Figure 13] A diagram showing the format of a Capabilities element for signaling information indicating the processing capabilities of a wireless communication terminal according to an embodiment of the present invention. [Figure 14] A diagram showing the format of a Block ACK frame according to an embodiment of the present invention. [Figure 15] 11 is a diagram illustrating a method in which a wireless communication terminal supporting fragmentation level 3 transmits a Block ACK frame according to an embodiment of the present invention. [Figure 16] 13 is a diagram illustrating a method in which a wireless communication terminal supporting fragmentation level 3 transmits a Block ACK frame according to another embodiment of the present invention. [Figure 17] 13 is a diagram illustrating a method in which a wireless communication terminal supporting fragmentation level 3 transmits a Block ACK frame according to yet another embodiment of the present invention. [Figure 18]13 is a diagram illustrating a method in which a wireless communication terminal supporting fragmentation level 3 transmits a Block ACK frame indicating All ACK according to yet another embodiment of the present invention. [Figure 19] 13 is a diagram illustrating a method in which a wireless communication terminal supporting fragmentation level 3 transmits a Block ACK frame indicating All ACK according to yet another embodiment of the present invention. [Figure 20] 13 is a diagram illustrating a method in which a wireless communication terminal supporting fragmentation level 3 transmits a Block ACK frame indicating All ACK according to yet another embodiment of the present invention. [Figure 21] 13 is a diagram illustrating an operation of a wireless communication terminal supporting fragmentation level 3 transmitting a Block ACK frame including a Block ACK Bitmap field indicating whether or not a fragment can be received according to yet another embodiment of the present invention. [Figure 22] FIG. 4 is a diagram illustrating the operation of a wireless communication terminal according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. In the drawings, parts that are not related to the description are omitted in order to clarify the present invention, and similar parts are designated by similar reference numerals throughout the specification.

[0031] Furthermore, when a part "comprises" a certain element, this does not mean excluding other elements, but rather further includes other elements, unless otherwise specified to the contrary.

[0032] This application claims priority based on Korean Patent Application Nos. 10-2016-0141302 (April 4, 2016), 10-2016-0059181 (May 14, 2016), and 10-2016-006242 (May 20, 2016), and the examples and descriptions described in each of the above applications which are the basis of priority are incorporated herein by reference in their entirety.

[0033] FIG 1 illustrates a wireless LAN system according to an embodiment of the present invention. A wireless LAN system includes one or more Basic Service Sets (BSS), which refers to a collection of devices that can successfully synchronize and communicate with each other. Generally, BSSs are classified into infrastructure BSSs and independent BSSs (IBSSs), of which FIG 1 illustrates an infrastructure BSS.

[0034] As shown in FIG. 1, the infrastructure BS S BSS1, BSS2 includes one or more stations STA1, STA2, STA3, STA4, STA5, access points PCP / AP-1, PCP / AP-2 which are stations providing distribution services, and a distribution system (SD) connecting multiple access points PCP / AP-1, PCP / AP-2.

[0035] A station (STA) is any device that includes a medium access control (MAC) based on the IEEE 802.11 standard and a physical layer interface for a wireless medium, and in a broad sense includes not only a non-AP but also an AP. In this specification, the term "terminal" refers to a non-AP STA or an AP, or is used as a term that refers to both. A station for wireless communication includes a processor and a transmit / receive unit, and further includes a user interface unit and a display unit, etc., depending on the embodiment. The processor generates frames to be transmitted through a wireless network, processes frames received through the wireless network, and performs various other processes for controlling the station. The transmit / receive unit is functionally connected to the processor and transmits and receives frames through the wireless network for the station.

[0036] An Access Point (AP) is an entity that provides a connection to a distribution system DS via a wireless medium for stations associated with it. In an infrastructure BSS, communication between non-AP stations is generally performed via the AP, but when a direct link is set up, direct communication between non-AP stations becomes possible. Meanwhile, in the present invention, the AP is used as a base including a PCP (Personal BSS Coordination Point), and in a broad sense, includes all concepts such as a central controller, a base station (GS), a Node B, a BTS (Base Transceiver System), or a site controller.

[0037] A plurality of infrastructure BSSs are interconnected via a distribution system, and the plurality of BSSs connected via the distribution system are referred to as an Extended Service Set (ESS).

[0038] 2 is a diagram showing an independent BSS, which is a wireless LAN system according to another embodiment of the present invention, in which the same or corresponding parts in the embodiment of FIG. 2 are the same as or correspond to the embodiment of FIG.

[0039] The BSS3 shown in Figure 2 is an independent BSS and does not include an AP, so all stations STA6 and STA7 are not connected to an AP. An independent BSS is a self-contained network that is not allowed to be connected to a distribution system. In an independent BSS, each station STA6 and STA7 is directly connected to each other.

[0040] FIG. 3 is a block diagram showing a configuration of a station 100 according to an embodiment of the present invention. As shown, station 100 according to an embodiment of the present invention includes a processor 110 , a transceiver 120 , a user interface 140 , a display unit 150 , and a memory 160 .

[0041] First, the transceiver 120 transmits and receives wireless signals such as wireless LAN packets, and is provided inside or outside the station 100. According to an embodiment, the transceiver 120 includes at least one transceiver module using different frequency bands. For example, the transceiver 120 includes transceiver modules using different frequency bands such as 2.4 GHz, 5 GHz, and 50 GHz. According to an embodiment, the station 100 includes a transceiver module using a frequency band of 6 GHz or more and a transceiver module using a frequency band of 6 GHz or less. Each transceiver module performs wireless communication with an AP or an external station according to the wireless LAN standard of the frequency band supported by the corresponding transceiver module. The transceiver 120 operates only one transceiver module at a time or operates multiple transceiver modules simultaneously according to the performance and requirements of the station 100. When the station 100 includes multiple transceiver modules, each transceiver module may be provided in an independent form, or multiple modules may be integrated into one chip.

[0042] Next, the user interface unit 140 is provided in the station 100 and includes various types of input / output means. That is, the user interface unit 140 receives user input using various input means, and the processor 110 controls the station 100 based on the received user input. Also, the user interface unit 140 performs output based on a command from the processor 110 using various output means.

[0043] Next, the display unit 150 outputs an image on a display screen. The display unit 150 outputs various display objects such as a user interface based on the contents or control commands of the processor 110. The memory 140 also stores control programs and various data used by the station 110. Such control programs include connection programs required for the station 100 to connect to an AP or an external station.

[0044] The processor 110 of the present invention executes various commands or programs to process data within the station 100. The processor 110 also controls each unit of the station 100 described above and controls data transmission and reception between the units. According to an embodiment of the present invention, the processor 110 executes a program for connection to an AP stored in the memory 160 and receives a communication setup message transmitted by the AP. The processor 110 also reads information on the priority conditions of the station 100 included in the communication setup message and requests a connection to the AP based on the information on the priority conditions of the station 100. The processor 110 of the present invention may refer to a main control unit of the station 100, or may refer to a control unit for individually controlling some components of the station 100, for example, the transceiver 120, depending on the embodiment. That is, the processor 110 is a modulation unit or demodulation unit (MPDUlator and / or deMPDUlator) that modulates a wireless signal transmitted and received from the transceiver 120. The processor 110 controls various operations of wireless signal transmission and reception of the station 100 according to an embodiment of the present invention. A specific embodiment of this will be described later.

[0045] The station 100 shown in FIG. 3 is a block diagram according to an embodiment of the present invention, and the separate blocks are used to logically distinguish the elements of the device. The above-mentioned device elements may be implemented in one chip or multiple chips depending on the design of the device. For example, the processor 110 and the transceiver 120 may be integrated and implemented in one chip, or may be implemented in separate chips. In addition, in an embodiment of the present invention, some components of the station 100, such as the user interface unit 140 and the display unit 150, may be selectively provided in the station 100.

[0046] FIG. 4 is a block diagram showing a configuration of an AP 200 according to an embodiment of the present invention.

[0047] As shown, an AP 200 according to an embodiment of the present invention includes a processor 210, a transceiver 220, and a memory 260. In Fig. 4, a duplicated description of parts of the configuration of the AP 200 that are the same as or correspond to the configuration of the station 100 in Fig. 3 will be omitted.

[0048] Referring to FIG. 4, the AP 200 according to the present invention includes a transceiver 220 for operating a BSS in at least one frequency band. As described in the embodiment of FIG. 3, the transceiver 220 of the AP 200 also includes a plurality of transceiver modules using different frequency bands. That is, the AP 200 according to the embodiment of the present invention includes two or more transceiver modules using different frequency bands, for example, 2.4 GHz, 5 GHz, and 60 GHz. Preferably, the AP 200 includes a transceiver module using a frequency band of 6 GHz or more and a transceiver module using a frequency band of 6 GHz or less. Each transceiver module performs wireless communication with a station according to the WLAN standard of the frequency band supported by the corresponding transceiver module. The transceiver 220 may operate only one transceiver module at a time or operate multiple transceiver modules simultaneously depending on the performance and requirements of the AP 200.

[0049] Next, the memory 260 stores control programs used by the AP 200 and various data associated therewith. Such control programs include a management program for managing station connections. Also, the processor 210 controls each unit of the AP 200 and controls data transmission and reception between the units. According to an embodiment of the present invention, the processor 210 executes a program for connecting with a station stored in the memory 260 and transmits a communication setup message for one or more stations. At this time, the communication setup message includes information regarding connection priority conditions of each station. Also, the processor 210 performs connection setup in response to a connection request from a station. According to an embodiment, the processor 210 is a modulation unit or demodulation unit that modulates a wireless signal transmitted and received from the transceiver unit 220. The processor 210 controls various operations of transmitting and receiving wireless signals of the AP 200 according to an embodiment of the present invention. A specific embodiment of this will be described later.

[0050] FIG. 5 illustrates a process in which a STA establishes a link with an AP.

[0051] 5, the link between the STA 100 and the AP 200 is set up through three steps: scanning, authentication, and association. First, the scanning step is a step in which the STA 100 acquires access information of the BSS operated by the AP 200. There are two methods for performing scanning: a passive scanning method in which the AP 200 acquires information only by using a beacon message S101 periodically transmitted by the AP 200, and an active scanning method in which the STA 10 transmits a probe request to the AP S103, receives a probe response from the AP S105, and acquires access information.

[0052] The STA100 that successfully receives wireless access information in the scanning step transmits an authentication request (S107a), receives an authentication response from the AP 200, and performs an authentication step (S107b). After the authentication step is performed, the STA100 transmits an association request (S109a), receives an association response from the AP 200, and performs an association step (S109b). In this specification, association basically means wireless association, but the present invention is not limited to this, and association in a broad sense includes both wireless association and wired association.

[0053] Meanwhile, an 802.1X-based authentication step S111 and an IP address acquisition step S113 via DHCP are additionally performed. In FIG 5, the authentication server 300 is a server that processes 802.1X-based authentication with the STA 100, and may be physically connected to the AP 200 or may exist as a separate server.

[0054] Due to the proliferation of mobile devices and the spread of wireless communication, wireless communication terminals are increasingly communicating in dense environments. In particular, wireless communication terminals are increasingly communicating in environments where multiple BSSs overlap. When multiple BSSs overlap, the communication efficiency of the wireless communication terminal may decrease due to interference with other wireless communication terminals. In particular, when using a frequency band through a contention procedure, the wireless communication terminal may not even be able to secure a transmission opportunity due to interference with other wireless communication terminals. To solve this problem, the wireless communication terminal performs a spatial reuse operation. In particular, the SR operation includes an operation of approaching a channel depending on whether a received frame is a frame transmitted from a BSS including the wireless communication terminal or a frame transmitted from another BSS. In a specific embodiment, the operation of approaching a channel includes a CCA operation and a deferral operation. For example, the wireless communication terminal adjusts a CCA threshold depending on whether a frame received by the wireless communication terminal is a frame transmitted from a BSS including the wireless communication terminal or a frame transmitted from an OBSS. In addition, the wireless communication terminal adjusts the transmission power of a PPDU to be transmitted depending on the result of the CCA operation during the SR operation. An embodiment for SR operation of a wireless communication terminal will be described with reference to FIGS.

[0055] For convenience of explanation, a BSS including a wireless communication terminal is called an Intra-BSS, a basic service set overlapping with an Intra-BSS is called an Overlapped Basic Service Set (OBSS), a frame transmitted from an Intra-BSS is called an Intra-BSS frame, and a frame transmitted from an OBSS is called an OBSS frame or an Inter-BSS frame.

[0056] The wireless communication terminal fragments at least one of one MSDU, one A (Aggregate)-MSDU, and one MPDU (management protocol data unit) and transmits the fragmented data. For convenience of explanation, a portion of the MSDU, a portion of the A-MSDU, or a portion of the MPDU generated through fragmentation is referred to as a fragmentation. In addition, a wireless communication terminal that transmits data is referred to as an originator, and a wireless communication terminal that receives data is referred to as a recipient.

[0057] In detail, the wireless communication terminal fragments at least one of one MSDU, one A-MSDU, and one MPDU to generate a plurality of fragments. At this time, the wireless communication terminal transmits the generated plurality of fragments to a plurality of MPDUs. Also, the wireless communication terminal receiving the plurality of fragments defragments the plurality of fragments to obtain at least one of one MSDU, one A-MSDU, and one MPDU. At this time, the MPDU may be an S-MPDU or an A-MPDU.

[0058] FIG. 6 is a diagram illustrating a method for transmitting information about a fragmentation level using ADDBA according to an embodiment of the present invention.

[0059] The receiver needs to have sufficient buffer capacity and processing capability to defragment multiple fragments. To this end, the transmitter needs to know the defragmentation level that the receiver can support. Therefore, the wireless communication terminal signals the fragmentation level indicating the degree of fragmentation that the wireless communication terminal can receive. In particular, the wireless communication terminal transmits information regarding the fragmentation level of the fragment that the wireless communication terminal can receive during the ring setup process with the wireless communication terminal that is an AP, and receives information regarding the fragmentation level of the fragment that the wireless communication terminal that is an AP can receive. In particular, the wireless communication terminal transmits information regarding the fragmentation level via an Operation element. In a specific embodiment, the wireless communication terminal transmits information regarding the fragmentation level via a Capabilities field of the Operation element. In this case, the Capabilities field is a field indicating the capability of the wireless communication terminal. In addition, the wireless communication terminal transmits information regarding the fragmentation level via at least one of a probe request frame, a probe response frame, an authentication request frame, an authentication response frame, an association request frame, and an association response frame. Also, fragmentation levels are divided into four levels. Level 0 indicates that the wireless communication terminal does not support fragmentation of the MSDU received. Also, level 1 indicates that the wireless communication terminal can receive an MPDU including one fragment. In this case, the MPDU is a single MPDU that is not aggregated with other MPDUs, or an MPDU that is not an A-MPDU. Also, level 2 indicates that the wireless communication terminal can receive an A-MPDU including one fragment for each MSDU. Specifically, level 2 indicates that the wireless communication terminal can receive an A-MPDU including one or less fragments for each MSDU. Level 3 indicates that the wireless communication terminal can receive an A-MPDU including multiple fragments for each MSDU. Specifically, level 3 indicates that the wireless communication terminal can receive an A-MPDU including four or less fragments for each MSDU.

[0060] In the embodiment of Fig. 6, the station STA transmits a probe request frame, probe req., to the access point AP. At this time, the station STA inserts information about a fragmentation level supported by the station into the probe request frame, probe req. In addition, the access point AP transmits a probe response frame, Probe resp., to the station STA. At this time, the access point AP inserts information about a fragmentation level supported by the access point AP into the probe response frame, Probe resp.

[0061] The station STA and the access point AP negotiate the transmission of a Block ACK frame via an ADDBA request frame ADDBA req. and an ADDBA response frame ADDBA resp. The station STA transmits an A-MPDU based on the information on the fragmentation level transmitted by the access point AP. In detail, the station STA transmits an A-MPDU including fragments of the fragmentation level supported by the access point AP to the access point AP based on the information on the fragmentation level transmitted by the access point AP. The access point AP transmits a Block ACK (BA) frame for the A-MPDU to the station STA.

[0062] When the receiver receives an A-MPDU that does not include a fragment or includes one fragment for each MSDU, the receiver transmits a Block ACK frame including a bitmap indicating whether each MSDU is received or not. When the receiver receives an A-MPDU that includes multiple fragments corresponding to one MSDU, the receiver transmits a Block ACK frame including a bitmap indicating whether each fragment is received or not. A specific form of the Block ACK frame will be described with reference to Figures 14 to 22.

[0063] If a receiver supports fragmentation level 3 and fails to receive one or more of the MPDUs contained in the A-MPDU, the receiver cannot know whether the transmitter transmitted multiple fragments of one MSDU via the A-MPDU. Therefore, a receiver that supports level 3 must always transmit a Block ACK frame that includes a bitmap indicating whether each fragment was received or not.

[0064] In addition, link setup is performed only when the wireless communication terminal accesses a new BSS. Therefore, if information regarding the fragmentation level is transmitted through the link setup procedure, unnecessary link setup must be performed again to further set the fragmentation level after the link setup is performed. Therefore, it is difficult for the wireless communication terminal to reconfigure the fragmentation level depending on the network situation. In addition, in the link setup process, it is difficult for the wireless communication terminal to identify the type of traffic that the wireless communication terminal receives or transmits. In addition, if the wireless communication terminal transmits information regarding the fragmentation level through the link setup, it may be difficult for the wireless communication terminal to specify the fragmentation level for each type of traffic.

[0065] Considering these points, a method is needed to efficiently transmit information about the fragmentation level and to allow a sender and a sender to dynamically negotiate the fragmentation level. An embodiment of transmitting information about the fragmentation level and negotiating the fragmentation level will be described with reference to Figs. 6 to 14.

[0066] FIG. 7 is a diagram showing formats of an ADDBA request frame and an ADDBA response frame for signaling information related to a fragmentation level according to another embodiment of the present invention.

[0067] The transmitter signals the fragmentation level to be used during data transmission through an ADDBA (Add Block Acknowledgment) setting procedure that transmits a Block ACK frame. The transmitter also determines the fragmentation level to be used during data transmission based on information about the fragmentation level signaled by the receiver through the ADDBA procedure. More specifically, the transmitter transmits an ADDBA request frame including parameters related to the Block ACK frame to the receiver. The receiver transmits an ADDBA response frame to the transmitter to set up transmission of the Block ACK frame. At this time, the ADDBA request frame and the ADDBA response frame are types of action frames. Thus, the wireless communication terminal can transmit the ADDBA request frame when necessary. When the fragmentation level to be used during data transmission is determined through the ADDBA procedure that sets up transmission of a Block ACK frame, the transmitter and receiver can more flexibly change the fragmentation level to be used for data transmission.

[0068] In the ADDBA setting procedure, the transmitter transmits information regarding the fragmentation level intended to be used when transmitting data to the receiver. Specifically, the transmitter transmits information regarding the fragmentation level intended to be used when transmitting data through the ADDBA request frame. The information regarding the fragmentation level indicates the maximum fragmentation level intended to be used when transmitting data through the ADDBA request frame. Also, the information regarding the fragmentation level may be specified for each TID. Specifically, the transmitter transmits information regarding the fragmentation level intended to be used when transmitting data corresponding to a specific TID through the ADDBA request frame. The specific TID may be a TID specified in the Block ACK Parameter Set of the ADDBA request frame. For example, the transmitter sets the fragmentation level signaled by the ADDBA request frame to level 0, signaling that the transmitter does not intend to perform fragmentation when transmitting data related to the corresponding TID. Also, the transmitter sets the fragmentation level signaled by the ADDBA request frame to level 1, signaling that the transmitter intends to transmit fragments corresponding to level 1 or lower when transmitting data related to the corresponding TID. In detail, the transmitter sets the fragmentation level signaled by the ADDBA request frame to level 1, indicating that the transmitter will transmit one MPDU including one fragment when transmitting data for the corresponding TID. In this case, the MPDU is a single MPDU that is not combined with other MPDUs as described above, or an MPDU that is not an A-MPDU. In addition, the transmitter sets the fragmentation level signaled by the ADDBA request frame to level 2, signaling that the transmitter will transmit fragments that are level 2 or lower when transmitting data for the corresponding TID. In detail, the transmitter sets the fragmentation level signaled by the ADDBA request frame to level 2, signaling that the transmitter will transmit one or less fragments per MPDU when transmitting data for the corresponding TID via A-MPDU.In addition, the transmitter sets the fragmentation level signaled by the ADDBA request frame to level 3, and signals that the transmitter intends to transmit fragments of level 3 or less when transmitting data for the corresponding TID. In particular, the transmitter sets the fragmentation level signaled by the ADDBA request frame to level 3, and signals that the transmitter intends to transmit 4 or less fragments per MPDU when transmitting data for the corresponding TID via A-MPDU.

[0069] In addition, in the ADDBA setting procedure, the receiver transmits information regarding the fragmentation level that the receiver is capable of supporting when receiving data to the transmitter. Specifically, the receiver transmits information regarding the fragmentation level that the receiver is capable of supporting when receiving data through the ADDBA response frame. The information regarding the fragmentation level is the maximum fragmentation level of the fragment that the receiver can receive. Also, the information regarding the fragmentation level may be specified for each TID. Specifically, the receiver transmits information regarding the fragmentation level that the receiver is capable of supporting when receiving data corresponding to a specific TID through the ADDBA response frame. The specific TID may be a TID specified in the Block ACK Parameter Set of the ADDBA response frame. For example, the receiver sets the fragmentation level signaled by the ADDBA response frame to level 0, signaling that the receiver cannot receive fragments when receiving data related to the corresponding TID. In addition, the receiver sets the fragmentation level signaled by the ADDBA response frame to level 1, signaling that the receiver can transmit only fragments that fall under level 1 or lower when transmitting data related to the corresponding TID. In particular, the receiver sets the fragmentation level signaled by the ADDBA response frame to level 1, indicating that the receiver can receive one MPDU containing one fragment when receiving data related to the corresponding TID. In this case, the MPDU is a single MPDU that is not combined with other MPDUs as described above, or an MPDU that is not an A-MPDU. In addition, the receiver sets the fragmentation level signaled by the ADDBA response frame to level 2, signaling that the receiver can receive fragments that fall under level 1 or level 2 when receiving data related to the corresponding TID. In particular, the receiver sets the fragmentation level signaled by the ADDBA response frame to level 2, signaling that the receiver can receive one MPDU containing one fragment, or an A-MPDU containing one or less fragments per MSDU.In addition, the receiver sets the fragmentation level signaled by the ADDBA response frame to level 3, signaling that when the receiver receives data for the corresponding TID, it may receive fragments corresponding to level 1, level 2, or level 3. In particular, the receiver sets the fragmentation level signaled by the ADDBA response frame to level 3, signaling that the receiver may receive one MPDU containing one fragment or an A-MPDU containing up to four fragments per MPDU.

[0070] The transmitter receives information on the fragmentation level from the receiver. More specifically, the transmitter receives an ADDBA response frame and acquires information on the fragmentation level signaled by the ADDBA response frame. The transmitter determines a fragmentation level to be used when transmitting data based on the acquired information on the fragmentation level. More specifically, the transmitter fragments the data to a fragmentation level equal to or lower than the fragmentation level indicated by the acquired information on the fragmentation level and transmits the data. The receiver also selects a bitmap format of the Block ACK frame based on the determined fragmentation level. After the receiver receives the data, the receiver transmits a Block ACK frame having the selected bitmap format to the transmitter. Also, the transmitter operates based on the determined fragmentation level until the fragmentation level is further changed through the ADDBA procedure. More specifically, the transmitter operates based on the previously determined fragmentation level until the transmitter receives information on the fragmentation level through a new ADDBA setting procedure. In a specific embodiment, the transmitter operates based on the determined fragmentation level until the transmitter transmits a new ADDBA request frame and receives a new ADDBA response frame. The receiver also operates based on the fragmentation level determined through the ADDBA procedure, before the fragmentation level is further changed through the ADDBA procedure. Also, the transmitter operates based on the fragmentation level determined through the ADDBA procedure, regardless of the fragmentation level information transmitted during the link setup process. The receiver also operates based on the fragmentation level determined through the ADDBA procedure, regardless of the fragmentation level information transmitted during the link setup process.

[0071] In another specific embodiment, the transmitter requests a fragmentation level from the receiver that is less than or equal to the fragmentation level signaled by the receiver during the link setup process. More specifically, the transmitter signals to the receiver that a fragmentation level less than or equal to the level signaled by the receiver during the link setup process will be used for data to be transmitted to the receiver. Also, the receiver signals that it can receive a fragmentation level less than or equal to the fragmentation level requested by the transmitter.

[0072] In a specific embodiment, the transmitter and receiver transmit information about the fragmentation level through the ADDBA Capabilities field included in the ADDBA request frame and the ADDBA response frame. In this case, the ADDBA Capabilities field includes a Multiple Fragmentation field indicating the fragmentation level. The Multiple Fragmentation field is a 1-bit field indicating whether the fragmentation level is lower than level 2 or is equal to or higher than level 2. In another specific embodiment, the Multiple Fragmentation field may be a 2-bit field indicating which level the fragmentation level is from level 0 to level 3. Specific formats of the ADDBA request frame and the ADDBA response frame are shown in FIG. 7(a). Also, the formats of the ADDBA Capabilities field are shown in FIG. 7(b) and FIG. 7(c).

[0073] FIG. 8 is a diagram showing a MAC frame format for signaling information regarding a fragmentation level according to still another embodiment of the present invention.

[0074] The transmitter transmits information on the fragmentation level via an MPDU including data. More specifically, the transmitter transmits information on the fragmentation level via a Sequence Control field of an MPDU including data. The legacy wireless communication terminal fragments one MSDU into a maximum of 16 fragments and transmits the fragments. Therefore, the legacy wireless communication terminal sets a Fragment Number field indicating a fragment number to a 4-bit field in the Sequence Control field of the MPDU. The wireless communication terminal according to the embodiment of the present invention fragments one MSDU into a maximum of four fragments and transmits the fragments. Therefore, the wireless communication terminal according to the embodiment of the present invention sets a Fragment Number field indicating a fragment number to a 2-bit field in the Sequence Control field of the MPDU. At this time, the wireless communication terminal sets the remaining 2 bits to a Multiple Fragmentation field indicating a fragmentation level or a reserved bit. More specifically, the Multiple Fragmentation field is a 1-bit field indicating whether the fragmentation level is a level lower than level 2 or a level equal to or higher than level 2. In another specific embodiment, the Multiple Fragmentation field may be a 2-bit field indicating which level the fragmentation level is from level 0 to level 3. A specific MPDU format is as shown in FIG. 8(a). Also, the Sequence Control field format is as shown in FIG. 8(b). In still another specific embodiment, the transmitter transmits information regarding the fragmentation level via a header of an MPDU including data. In this case, the transmitter transmits information regarding the fragmentation level via a Frame Control element of the header of an MPDU including data.

[0075] The receiver selects the format of the Block ACK frame based on the ADDBA response frame. At this time, the receiver transmits a Block ACK frame for the data transmitted by the transmitter according to the selected Block ACK frame format. In more detail, if the transmitter indicates the fragmentation level for each MPDU containing data, the receiver can clearly recognize the fragmentation level used in the data transmission received by the receiver. Therefore, the receiver selects the format of the Block ACK frame according to the fragmentation level. At this time, the receiver transmits a Block ACK frame for the data transmitted by the transmitter according to the selected Block ACK frame format.

[0076] FIG. 9 is a diagram showing formats of an ADDBA response frame and an ADDBA request frame for signaling information related to a fragmentation level according to yet another embodiment of the present invention.

[0077] In the embodiment described through FIG. 7, the receiver signals information about the fragmentation level through the Buffer Size field, not the ADDBA Capabilities field of the ADDBA response frame. In particular, the receiver sets some bits of the Buffer Size field of the ADDBA response frame to signal information about the fragmentation level. In a specific embodiment, the receiver sets the LSB1 bit or the MSB1 bit of the Buffer Size field of the ADDBA response frame to signal information about the fragmentation level. At this time, the information about the fragmentation level indicates whether the fragmentation level is lower than level 2 or is equal to or higher than level 2. In another specific embodiment, the receiver sets the LSB2 bits or the MSB2 bits of the Buffer Size field of the ADDBA response frame to signal information about the fragmentation level. At this time, the information about the fragmentation level indicates which level the fragmentation level is from level 0 to level 3.

[0078] In detail, the receiver implicitly signals information about the fragmentation level through the size of the value indicated by the Buffer Size field of the ADDBA response frame. For example, if the value of the Buffer Size field is 0, the Buffer Size field indicates that the fragmentation level is level 0. If the value of the Buffer Size field is 1, the Buffer Size field indicates that the fragmentation level is level 1. If the value of the Buffer Size field is greater than or equal to 2 and less than or equal to 63, the Buffer Size field indicates that the fragmentation level is level 2. If the value of the Buffer Size field is greater than or equal to 64 and less than or equal to 1023, the Buffer Size field indicates that the fragmentation level is level 3.

[0079] In addition, the transmitter signals information about the fragmentation level through the Buffer Size field of the ADDBA response frame. In this case, the format and signaling method of the Buffer Size field are the same as those in the embodiment in which the receiver signals information about the fragmentation level through the ADDBA response frame described above.

[0080] Also, the transmitter and receiver may signal information regarding the fragmentation level for each TID as described in Figure 7. In this case, the TID is specified by the Block ACK Parameter Set field.

[0081] A specific format of the ADDBA response frame and the ADDBA request frame is as shown in the embodiment of Fig. 9(a), and the format of the Block ACK Parameter Set field is as shown in the embodiment of Fig. 9(b).

[0082] FIG. 10 is a diagram showing formats of an ADDBA response frame and an ADDBA request frame for signaling information related to a fragmentation level according to yet another embodiment of the present invention.

[0083] When the ADDBA response frame sets the transmission of Block ACK frames for multiple TIDs, the receiver sets a subfield of the Block ACK Parameter Set field to indicate that the information on the corresponding fragmentation level applies to all TIDs for which the ADDBA response frame sets the transmission of Block ACK frames. In this case, the subfield of the Block ACK Parameter Set field is called the All TID field. The All TID field is a 1-bit field.

[0084] In addition, when the ADDBA request frame sets the transmission of Block ACK frames for multiple TIDs, the transmitter sets a subfield of the Block ACK Parameter Set field to indicate that the information on the corresponding fragmentation level applies to all TIDs indicated by the ADDBA response frame. In this case, the subfield of the Block ACK Parameter Set field set by the transmitter is called the All TID field. The All TID field is a 1-bit field.

[0085] Specific formats of the ADDBA response frame and the ADDBA request frame are as shown in the embodiment of Fig. 10(a), and the format of the Block ACK Parameter Set field is as shown in the embodiment of Fig. 10(b). Operations of the transmitter and the receiver, except for the setting of the All TID field, may be the same as those of the transmitter and the receiver in the embodiment of Fig. 9. Also, the format of the ADDBA request frame and the ADDBA response frame, except for the All TID field, may be the same as the format of the ADDBA request frame and the ADDBA response frame described in the embodiment of Fig. 9.

[0086] In the embodiment described with reference to FIGS. 7 to 10, the transmitter and receiver exchange information on the fragmentation level on a one-to-one basis. Also, when the information on the fragmentation level is transmitted using the ADDBA procedure, the fragmentation level used for data transmission is determined through a 4-way handshake. Therefore, a relatively long time is required before the fragmentation level used for data transmission is determined. When the wireless communication terminal transmits information on the fragmentation level through a trigger frame, one wireless communication terminal transmits information on the fragmentation level to multiple wireless communication terminals. Also, the fragmentation level used for data transmission is determined within a relatively short time. This will be described with reference to FIGS. 11 and 12.

[0087] FIG. 11 is a diagram showing a trigger frame format for signaling information regarding fragmentation levels according to yet another embodiment of the present invention.

[0088] The wireless communication terminal transmits information about a fragmentation level through a trigger frame. At this time, the trigger frame triggers an uplink multi-user (UL MU) transmission. In detail, the information about the fragmentation level signaled through the trigger frame indicates a fragmentation level that the wireless communication terminal transmitting the trigger frame can support when receiving data. In a specific embodiment, the information about the fragmentation level signaled through the trigger frame indicates a fragmentation level that the wireless communication terminal transmitting the trigger frame can support when receiving data based on the trigger frame. The field indicating the information about the fragmentation level is called a Multiple Fragments field. In a specific embodiment, the wireless communication terminal inserts a Multiple Fragments field into a Common Info field of the trigger frame. At this time, the format of the trigger frame is as in the embodiment of FIG. 11(a). For example, the wireless communication terminal inserts a Multiple Fragments field into a Trigger Dependent Common Info field of the trigger frame as in the embodiment of FIG. 11(c). In another specific embodiment, the wireless communication terminal may insert a Multiple Fragments field in addition to the Trigger Dependent Common Info field into the Common Info field, as in the embodiment of FIG. 11(b).

[0089] As in the above embodiment, the Multiple Fragmentation field is a 1-bit field indicating whether the fragmentation level is lower than level 2 or is equal to or higher than level 2. In another specific embodiment, the Multiple Fragmentation field may be a 2-bit field indicating which level the fragmentation level is from level 0 to level 3.

[0090] Since the Common Info field of the trigger frame is information commonly applied to wireless communication terminals receiving the trigger frame, the wireless communication terminal signals information about the same fragmentation level to all wireless communication terminals receiving the trigger frame. Since there may be differences in processing capabilities between wireless communication terminals, it is inefficient to apply the same fragmentation level to all. Therefore, a method is required for the wireless communication terminal to signal information about the fragmentation level individually to each of the multiple wireless communication terminals. This will be described with reference to FIG. 12.

[0091] FIG. 12 is a diagram showing a trigger frame format for signaling information regarding fragmentation levels according to yet another embodiment of the present invention.

[0092] The wireless communication terminal signals information on the fragmentation level applied to the wireless communication terminal, which corresponds to the Per User Info field, through the Per User Info field of the trigger frame. At this time, the format of the information on the fragmentation level is the same as that of the embodiment described with reference to FIG. 11. The format of the information on the fragmentation level is the same as that of the embodiment described with reference to FIG. 11. In particular, the information on the fragmentation level is information on the restriction of the fragmentation level used for transmitting data based on the trigger frame. The field indicating the information on the fragmentation level is referred to as a Multiple Fragments field. The field indicating the information on the fragmentation level is referred to as a Multiple Fragments field.

[0093] The format of the trigger frame is as in the embodiment of Fig. 12(a). In particular, the wireless communication terminal inserts a Multiple Fragments field into the Trigger Dependent Per User Info field as in the embodiment of Fig. 12(c). In another specific embodiment, the wireless communication terminal inserts a Multiple Fragments field into a Per User Info field other than the Trigger Dependent Per User Info field as in the embodiment of Fig. 12(b). The specific format of the Multiple Fragments field is as described in the embodiment of Fig. 11.

[0094] When a relatively high fragmentation level is permitted to the transmitter, the transmitter generates fragments of various lengths and selectively transmits the fragments according to the length of the A-MPDU. In this case, a wireless communication terminal with a relatively low processing capability can also rapidly transmit A-MPDUs of various lengths. To this end, the receiver permits the transmitter to have a relatively high fragmentation level in consideration of the transmitter's processing capability. For this operation, the transmitter needs a method of signaling the transmitter's processing capability to the receiver. This will be described with reference to FIG. 13.

[0095] FIG. 13 is a diagram showing a format of a Capabilities element for signaling information indicating the processing capabilities of a wireless communication terminal according to an embodiment of the present invention.

[0096] The wireless communication terminal signals information indicating a request for allowing multiple fragment transmissions during a link setup process. In this case, the wireless communication terminal receiving the information indicating the request for allowing multiple fragment transmissions determines a fragmentation level permitted for the wireless communication terminal that transmitted the information indicating the request for allowing multiple fragment transmissions based on the information indicating the request for allowing multiple fragment transmissions. In particular, the wireless communication terminal receiving the information indicating the request for allowing multiple fragment transmissions determines the fragmentation level permitted for the wireless communication terminal that transmitted the information indicating the request for allowing multiple fragment transmissions to be level 2.

[0097] In detail, the wireless communication terminal signals information indicating the processing capability of the wireless communication terminal and information indicating a request for allowing multiple fragment transmissions via at least one of an authentication request frame, an association request frame, and a probe request frame. In a specific embodiment, the wireless communication terminal signals information indicating a request for allowing multiple fragment transmissions via a Capabilities element. In a specific embodiment, the wireless communication terminal inserts a Low Processing field indicating a request for allowing multiple fragment transmissions into the Capabilities element. For example, if the value of the Low Processing field is 1, the Low Processing field indicates that permission for multiple fragment transmissions is requested.

[0098] In determining the fragmentation level, priority is given to whether a wireless communication terminal that has received information indicating a request to allow multiple fragment transmissions can receive multiple fragments, rather than whether permission for multiple fragment transmissions is requested. This is because fragment transmission cannot be permitted if the recipient fragment cannot be received. Thus, a wireless communication terminal that has received information indicating a request to allow multiple fragment transmissions may not allow multiple fragment transmissions even if permission for multiple fragment transmissions is requested. In particular, a wireless communication terminal that has received information indicating a request to allow multiple fragment transmissions may set the fragmentation level to level 0 or level 1, even if permission for multiple fragment transmissions is requested.

[0099] FIG. 14 is a diagram illustrating a format of a Block ACK frame according to an embodiment of the present invention. The receiver transmits in one Block ACK frame whether or not it is possible to receive multiple MPDUs transmitted by the transmitter. The receiver can improve transmission efficiency by transmitting a Block ACK frame compared to transmitting an ACK for each individual MPDU. The Block ACK frame includes a BA Information field that includes information on whether or not an MPDU is received. A specific format of the Block ACK frame is as shown in the embodiment of FIG. 14(b). At this time, the BA Information field includes a Block ACK Bitmap field. A specific format of the BA Information field is as shown in the embodiment of FIG. 14(c). Also, the format of the BA Control field is as shown in the embodiment of FIG. 14(a).

[0100] The Block ACK Bitmap field is a bitmap indicating whether the above-mentioned data can be received. The legacy wireless communication terminal transmits one MSDU in a maximum of 16 fragments. Therefore, the legacy wireless communication terminal indicates whether the fragments included in each of the 64 MSDUs can be received by using the Block ACK Bitmap field having a length of 128 bytes. In detail, the legacy wireless communication terminal assigns each of the 1024 bits of the Block ACK Bitmap field to each fragment included in the MSDU, and sets the bit corresponding to the received fragment to 1. The legacy wireless communication terminal can indicate whether all fragments can be received through the Block ACK Bitmap field. Therefore, the Block ACK Bitmap field sets the Fragment Number field of the Block ACK Starting Sequence Control field as a reserved field, and uses only the Sequence Number field. A specific format of the Block ACK Starting Sequence Control field is as shown in the embodiment of FIG. 14(d).

[0101] As described above, the wireless communication terminal according to the embodiment of the present invention fragments one MSDU into a maximum of four fragments. Also, the number of fragments that the wireless communication terminal can generate by fragmenting the MSDU may vary depending on the fragmentation level. Therefore, the wireless communication terminal changes the display method of the Block ACK Bitmap field depending on the fragmentation level. In detail, if the fragmentation level applied to the data received by the wireless communication terminal is lower than level 3, the wireless communication terminal sets each bit of the Block ACK Bitmap field to indicate whether each MSDU can be received. Also, if the fragmentation level applied to the data received by the wireless communication terminal is level 3, the wireless communication terminal sets each bit of the Block ACK Bitmap field to indicate whether each fragment can be received. This will be described with reference to FIG. 15 to FIG. 21.

[0102] FIG. 15 is a diagram illustrating a method in which a wireless communication terminal supporting fragmentation level: level 3 transmits a Block ACK frame according to an embodiment of the present invention.

[0103] Even if the transmitter can use level 3 as a fragmentation level, the receiver determines the format of the Block ACK Bitmap field based on the fragment number of the received fragment. In particular, if the fragment numbers of the fragments received by the receiver are all 0, the receiver transmits to the transmitter a Block ACK frame including a Block ACK Bitmap field in which each bit indicates whether or not a sequence is received. In this embodiment, even if the transmitter transmits an A-MPDU including a fragment, when the transmitter receives a Block ACK frame including a Block ACK Bitmap field in which each bit indicates whether or not a sequence is received, the transmitter determines the received Block ACK frame as a Block ACK frame indicating whether or not a fragment with a fragment number of 0 is received. If the fragment number of any one of the multiple fragments received by the receiver is not 0, the receiver transmits a Block ACK frame including a Block ACK Bitmap field in which each bit indicates whether or not a fragment is received.

[0104] In the embodiment of FIG. 15(a), the receiver receives an MPDU including a fragment with a fragment number of 0 and an unfragmented MSDU. More specifically, the receiver receives a fragment with a sequence number of 31 and a fragment number of 0. Since the fragment numbers of the fragments received by the receiver are all 0, the receiver transmits a Block ACK frame in which each bit of the Block ACK Bitmap field indicates whether the MSDU can be received or not. Next, the receiver receives an MPDU including multiple fragments and an unfragmented MSDU. At this time, the fragments received by the receiver include a fragment with a fragment number of 1, not 0. Therefore, the receiver transmits a Block ACK frame in which each bit of the Block ACK Bitmap field indicates whether the fragment can be received or not.

[0105] 15(b), the receiver also receives an MPDU including multiple fragments and an unfragmented MSDU. In this case, the fragments received by the receiver include a fragment with a fragmentation number of 1, not 0. Therefore, the receiver transmits a Block ACK frame in which each bit in the Block ACK Bitmap field indicates whether or not the fragment can be received.

[0106] FIG. 16 is a diagram illustrating a method for a wireless communication terminal supporting fragmentation level: level 3 to transmit a Block ACK frame according to still another embodiment of the present invention.

[0107] If the fragment numbers of the fragments received by the receiver are all 0, the receiver transmits a Block ACK frame including a Block ACK Bitmap field in which each bit indicates whether or not a sequence is received, regardless of the fragmentation level intended by the transmitter. The receiver determines the fragmentation level intended by the transmitter according to the embodiments described in Figures 7 to 14. Other operations of the receiver may follow the embodiment described in Figure 15.

[0108] In the embodiment of Figure 16, the receiver receives only the MPDU including the fragment with fragment number 0 and the unfragmented MSDU. The transmitter transmits one fragment with sequence number 31 and fragment number 1, and two fragments with sequence number 33 and fragment numbers 1 and 2, respectively, but the receiver cannot receive three fragments. Therefore, the receiver receives only the fragment with fragment number 0. Therefore, the receiver transmits a Block ACK frame including a Block ACK Bitmap field in which each bit indicates whether or not a sequence is received.

[0109] FIG. 17 is a diagram illustrating a method for a wireless communication terminal supporting fragmentation level: level 3 to transmit a Block ACK frame according to still another embodiment of the present invention. If the receiver receives all MSDUs corresponding to a certain TID, even if any one of the MSDUs corresponding to the TID is fragmented, the receiver transmits a Block ACK frame including a Block ACK Bitmap field in which each bit indicates whether or not the sequence is received, for the corresponding TID. In this case, the receiver determines whether or not all MSDUs corresponding to a certain TID are received based on the sequence number, the fragment number, and the More Fragment field. Also, if the receiver is unable to receive any fragment, the receiver transmits a Block ACK frame in which each Block ACK Bitmap field indicates whether or not the fragment is received. However, if the receiver is unable to receive all MSDUs corresponding to a certain sequence number, the receiver transmits a Block ACK frame including a Block ACK Bitmap field in which each bit indicates whether or not the sequence is received. In this embodiment, the transmitter can easily determine whether or not the data is fragmented when transmitting data to the receiver. Therefore, even if the receiver transmits a Block ACK frame that includes a Block ACK Bitmap field in which each bit indicates whether a sequence has been received, the transmitter can clearly determine whether the receiver has received the fragments transmitted by the transmitter.

[0110] In the embodiment of Figure 17, the transmitter fragments some of the MSDUs with a TID value of 1 and transmits them to the receiver. The receiver receives all MSDUs for TID value 1 (sequence numbers 31 to 63). In particular, the receiver receives MSDUs with sequence numbers 31, 33, 63, etc. as fragments. The receiver transmits a Block ACK frame for TID value 1. At this time, since the receiver has received all MSDUs for TID value 1, the receiver sets each bit in the Block ACK Bitmap field of the Block ACK frame for TID value 1 to indicate whether the MSDUs can be received or not.

[0111] 18 to 20 are diagrams illustrating a method in which a wireless communication terminal supporting fragmentation level: level 3 transmits a Block ACK frame indicating All ACK according to still another embodiment of the present invention.

[0112] Even if at least one MSDU corresponding to a specific TID is fragmented, if the receiver receives all MPDUs in the A-MPDU, the receiver transmits a Block ACK frame indicating All ACK. All MPDUs in the A-MPDU may correspond to not only a specific TID but also other TIDs. In this case, if the receiver receives all MSDUs corresponding to a specific TID and all MPDUs corresponding to other TIDs in the A-MPDU, the receiver determines that it has received all MPDUs in the A-MPDU. In this case, even if the value of the More Fragment field of the fragment corresponding to a specific TID that the receiver last received is 1, if the receiver receives all other MPDUs transmitted following the last fragment, the receiver determines that it has received all MPDUs corresponding to the corresponding TID included in the A-MPDU. In this case, the receiver transmits a Block ACK frame including a Block ACK Bitmap field in which each bit indicates whether or not an MSDU is received. Also, as described above, when the receiver receives all MPDUs corresponding to a specific TID and other TIDs, the receiver transmits a Block ACK frame indicating All ACK.

[0113] Also, a Block ACK frame indicating All ACK does not include a Block ACK Bitmap field and is a Block ACK frame indicating that MPDUs for all TIDs indicated by the Block ACK frame have been received. In more detail, the receiver inserts the AID of the transmitter into the Per AID TID Info field, sets the ACK type to a value indicating All ACK, and inserts the corresponding TID.

[0114] In the embodiment of Fig. 18, the transmitter fragments some of the MSDUs with a TID value of 1 and transmits them to the receiver, as in the embodiment of Fig. 17. The receiver STA1 receives all MSDUs for TID value 1 (sequence numbers 31 to 63). At this time, the receiver STA1 receives all MPDUs in the A-MSDU that transmits the MSDUs with TID value 1. Therefore, the receiver STA1 inserts the TID value 1 and an AID indicating the receiver STA1, sets the ACK Type to All ACK, and transmits a Block ACK frame.

[0115] In the embodiment of FIG. 19, the receiver STA1 receives an MSDU (sequence numbers 31 to 63) corresponding to TID value 1. At this time, the value of the More Fragment field of the fragment (sequence number 63, fragment number 1) that the receiver STA1 received last among the fragments corresponding to TID value 1 is 1. At this time, the receiver STA1 determines that it has received all the fragments corresponding to TID1 transmitted in the A-MPDU based on the fact that it has received all the MPDUs transmitted after the corresponding fragment (sequence number 63, fragment number 1) in the A-MPDU. Therefore, the receiver STA1 inserts the TID value 1 and an AID indicating the receiver STA1, sets the ACK Type to All ACK, and transmits a Block ACK frame.

[0116] In the embodiment of Fig. 20, receiver STA1 receives MSDUs (sequence numbers 31 to 63) corresponding to TID value 1. However, receiver STA1 cannot receive the fragment corresponding to sequence number 64 and fragment number 0. In this case, receiver STA1 only recognizes that it was unable to receive a specific MPDU, but cannot determine which fragment it was unable to receive. Therefore, receiver STA1 sets each bit in the Block ACK Bitmap field to indicate whether or not it is possible to receive an MSDU, and transmits a Block ACK frame for TID value 1.

[0117] FIG. 21 is a diagram illustrating an operation of a wireless communication terminal supporting fragmentation level: level 3 transmitting a Block ACK frame including a Block ACK Bitmap field indicating whether or not a fragment can be received according to another embodiment of the present invention.

[0118] As described above with reference to Figures 18-20, if the conditions of the embodiment are not met, the receiver transmits a Block ACK frame for a particular TID that includes a Block ACK Bitmap field, each bit of which indicates whether or not a fragment was received.

[0119] In the embodiment of Figure 21(a), the receiver cannot receive a fragment that corresponds to a particular TID, has a sequence number of 64, and has a fragment number of 0. The receiver recognizes that it received a fragment that corresponds to a particular TID, has a sequence number of 64, and has a fragment number of 1, and could not receive a fragment that corresponds to a particular TID, has a sequence number of 64, and has a fragment number of 0. Thus, the receiver transmits a Block ACK frame for the particular TID that includes a Block ACK Bitmap field, each bit of which indicates whether or not a fragment can be received.

[0120] In the embodiment of Figure 21(b), the receiver cannot receive a fragment that corresponds to a particular TID, has a sequence number of 33, and has a fragment number of 2. The receiver receives fragments that correspond to a particular TID and have sequence numbers greater than 33, and realizes that it could not receive a fragment with sequence number 33 and fragment number 2. Therefore, the receiver transmits a Block ACK frame for the particular TID that includes a Block ACK Bitmap field, each bit of which indicates whether or not the fragment was received.

[0121] In the embodiment of Figure 21 (c), the receiver receives a fragment with sequence number 63 and fragment number 1 for a specific TID, and is unable to receive the MPDU transmitted later. In this case, the value of the More Fragment field of the last transmitted fragment is 1, so the receiver is unable to determine whether it has received all fragments transmitted in the A-MPDU for a specific TID. Therefore, the receiver transmits a Block ACK frame for the specific TID, which includes a Block ACK Bitmap field, each bit of which indicates whether a fragment can be received or not.

[0122] FIG. 22 is a diagram illustrating the operation of a wireless communication terminal according to an embodiment of the present invention.

[0123] As described above, the transmitter 2201 transmits the first information on the fragmentation level to the receiver 2203 in the ADDBA setting procedure. More specifically, the transmitter 2201 transmits an ADDBA request frame including the first information on the fragmentation level to the receiver 2203 S2201. More specifically, the transmitter 2201 inserts the first information on the fragmentation level to be used for data to be transmitted to the receiver 2203 into the ADDBA request frame. The transmitter 2201 transmits the corresponding ADDBA request frame to the receiver 2203. The first information may be specified for each TID. More specifically, the first information relates to a fragmentation level to be used when the transmitter 2201 transmits data corresponding to a specific TID to the receiver 2203. In a specific embodiment, the specific TID may be a TID specified in a Block ACK Parameter Set of the ADDBA request frame.

[0124] Also, the first information indicates the maximum fragmentation level that the transmitter 2201 intends to use when transmitting data to the receiver 2203. More specifically, the transmitter 2201 sets the fragmentation level signaled by the first information to level 0, signaling that the transmitter 2201 does not intend to perform fragmentation when transmitting data related to the corresponding TID. Also, the transmitter 2201 sets the fragmentation level signaled by the first information to level 1, signaling that the transmitter intends to transmit fragments that are equal to or lower than level 1 when transmitting data related to the corresponding TID. More specifically, the transmitter 2201 sets the fragmentation level signaled by the first information to level 1, indicating that the transmitter 2201 transmits one MPDU including one fragment when transmitting data related to the corresponding TID. In this case, the MPDU is a single MPDU that is not combined with other MPDUs as described above, or is an MPDU that is not an A-MPDU. Also, the transmitter 2201 sets the fragmentation level signaled by the first information to level 2, and signals that the transmitter 2201 intends to transmit fragments that fall under level 2 or lower when transmitting data related to the corresponding TID. More specifically, the transmitter 2201 sets the fragmentation level signaled by the first information to level 2, and signals that the transmitter intends to transmit one or less fragments per MPDU when transmitting data related to the corresponding TID via A-MPDU. Also, the transmitter 2201 sets the fragmentation level signaled by the first information to level 3, and signals that the transmitter intends to transmit fragments that fall under level 3 or lower when transmitting data related to the corresponding TID. More specifically, the transmitter 2201 sets the fragmentation level signaled by the first information to level 3, and signals that the transmitter intends to transmit four or less fragments per MPDU when transmitting data related to the corresponding TID via A-MPDU.

[0125] When the transmitter 2201 transmits an ADDBA request frame including the first information to the receiver 2203, the transmitter 2201 inserts the first information into the ADDBA Capabilities field included in the ADDBA request frame. In detail, the ADDBA Capabilities field includes a Multiple Fragmentation field indicating a fragmentation level, as in the embodiment described with reference to FIG. 7. The Multiple Fragmentation field is a 1-bit field indicating whether the fragmentation level is a level lower than level 2 or a level equal to or higher than level 2. In another specific embodiment, the Multiple Fragmentation field may be a 2-bit field indicating which level the fragmentation level is, from level 0 to level 3.

[0126] The transmitter 2201 inserts the first information into the Buffer Size field of the ADDBA request frame, instead of the ADDBA Capabilities field, as in the embodiment described through FIG. 9 and FIG. 10. In particular, the transmitter 2201 sets some bits of the Buffer Size field of the ADDBA request frame to signal the first information. In a specific embodiment, the transmitter 2201 sets the LSB 1 bit or the MSB 1 bit of the Buffer Size field of the ADDBA request frame to signal the first information. At this time, the first information indicates whether the fragmentation level is a level lower than level 2 or a level equal to or higher than level 2. In another specific embodiment, the transmitter 2201 sets the LSB 2 bits or the MSB 2 bits of the Buffer Size field of the ADDBA request frame to signal information regarding the fragmentation level. At this time, the information regarding the fragmentation level indicates which level the fragmentation level is, from level 0 to level 3.

[0127] In another specific embodiment, the transmitter 2201 automatically signals information about the fragmentation level through the size of the value indicated by the Buffer Size field of the ADDBA request frame. For example, if the value of the Buffer Size field is 0, the Buffer Size field indicates that the fragmentation level is level 0. If the value of the Buffer Size field is 1, the Buffer Size field indicates that the fragmentation level is level 1. If the value of the Buffer Size field is equal to or greater than 2 and equal to or less than 63, the Buffer Size field indicates that the fragmentation level is level 2. If the value of the Buffer Size field is equal to or greater than 64 and equal to or less than 1023, the Buffer Size field indicates that the fragmentation level is level 3.

[0128] The receiver 2203 receives first information from the transmitter 2021 that intends to transmit data. More specifically, the receiver 2203 receives an ADDBA request frame from the transmitter 2021 that intends to transmit data. The receiver 2203 obtains first information regarding a fragmentation level that the transmitter 2201 intends to use for data to be transmitted to the receiver 2203 from the ADDBA request frame.

[0129] The receiver 2203 transmits second information regarding the fragmentation level to the transmitter 2201. The second information may be specified for each TID. The second information is information regarding the fragmentation level of fragments that the receiver 2203 may receive when the receiver 2203 receives data corresponding to a specific TID. The specific TID may be a TID specified in the Block ACK Parameter Set of the ADDBA response frame. More specifically, the receiver 2201 transmits an ADDBA response frame S2203 including the second information regarding the fragmentation level to the transmitter 2203. More specifically, the receiver 2203 inserts the second information into the ADDBA response frame. The receiver 2203 transmits the corresponding ADDBA response frame to the transmitter 2201.

[0130] In addition, the second information indicates the maximum fragmentation level that the receiver 2203 can receive. Specifically, the second information indicates levels 0 to 3 as described above. In a specific embodiment, the receiver 2203 sets the fragmentation level signaled by the ADDBA response frame to level 0, signaling that the receiver 2203 cannot receive fragments when receiving data related to the corresponding TID. In addition, the receiver 2203 sets the fragmentation level signaled by the second information to level 1, signaling that the receiver can transmit only fragments that are level 1 or lower when transmitting data related to the corresponding TID. Specifically, the receiver 2203 sets the fragmentation level signaled by the second information to level 1, indicating that the receiver 2203 receives one MPDU including one fragment when receiving data related to the corresponding TID. Also, the receiver 2203 sets the fragmentation level signaled by the second information to level 2, and signals that the receiver 2203 may receive fragments corresponding to level 1 or level 2 when transmitting data related to the corresponding TID. Specifically, the receiver 2203 sets the fragmentation level signaled by the second information to level 2, and signals that the receiver 2203 may receive one MPDU including one fragment, or an A-MPDU including one or less fragments per MSDU. Also, the receiver 2203 sets the fragmentation level signaled by the second information to level 3, and signals that the receiver 2203 may receive fragments corresponding to level 1, level 2, or level 3 when transmitting data related to the corresponding TID. Specifically, the receiver 2203 sets the fragmentation level signaled by the second information to level 3, and signals that the receiver 2203 may receive one MPDU including one fragment, or an A-MPDU including four or less fragments per MSDU.

[0131] The receiver 2203 inserts the first information into the ADDBA Capabilities field included in the ADDBA response frame. In detail, the ADDBA Capabilities field includes a Multiple Fragmentation field indicating a fragmentation level, as in the embodiment described with reference to FIG. 7. The Multiple Fragmentation field is a 1-bit field indicating whether the fragmentation level is lower than level 2 or is equal to or higher than level 2. In another specific embodiment, the Multiple Fragmentation field may be a 2-bit field indicating which level the fragmentation level is from level 0 to level 3.

[0132] The receiver 2203 inserts the first information into the Buffer Size field of the ADDBA response frame, instead of the ADDBA Capabilities field, as in the embodiment described with reference to FIG. 9 and FIG. 10. In particular, the receiver 2203 sets some bits of the Buffer Size field of the ADDBA response frame to signal the first information. In a specific embodiment, the receiver 2203 sets the LSB 1 bit or the MSB 1 bit of the Buffer Size field of the ADDBA response frame to signal the first information. At this time, the first information indicates whether the fragmentation level is a level lower than level 2 or a level equal to or higher than level 2. In another specific embodiment, the receiver 2203 sets the LSB 2 bits or the MSB 2 bits of the Buffer Size field of the ADDBA response frame to signal information regarding the fragmentation level. At this time, the information regarding the fragmentation level indicates which level the fragmentation level is, from level 0 to level 3.

[0133] In another specific embodiment, the receiver 2203 automatically signals information about the fragmentation level through the size of the value indicated by the Buffer Size field of the ADDBA response frame. For example, if the value of the Buffer Size field is 0, the Buffer Size field indicates that the fragmentation level is level 0. If the value of the Buffer Size field is 1, the Buffer Size field indicates that the fragmentation level is level 1. If the value of the Buffer Size field is equal to or greater than 2 and equal to or less than 63, the Buffer Size field indicates that the fragmentation level is level 2. If the value of the Buffer Size field is equal to or greater than 64 and equal to or less than 1023, the Buffer Size field indicates that the fragmentation level is level 3.

[0134] The transmitter 2201 acquires second information from the receiver 2203. More specifically, the transmitter 2201 receives an ADDBA response frame from the receiver 2203. The transmitter 2201 acquires the second information from the ADDBA response frame. At this time, the transmitter 2201 determines a fragmentation level of data corresponding to a specific TID based on the second information. More specifically, the transmitter 2201 determines a fragmentation level of data corresponding to a specific TID among data to be transmitted to the receiver 2203 based on the second information. More specifically, the transmitter 2201 determines a fragmentation level of data corresponding to a specific TID to be the same as or lower than the fragmentation level indicated by the second information.

[0135] The transmitter 2201 fragments data corresponding to a specific TID at the determined fragmentation level to generate fragments, and transmits the generated fragments to the receiver 2203. In particular, the transmitter 2201 fragments data corresponding to a specific TID at a fragmentation level that is the same as or lower than the fragmentation level indicated by the second information to generate fragments.

[0136] The receiver 2203 receives data including fragments from the transmitter 2201. The receiver 2203 selects the format of a Block ACK frame based on the ADDBBA request frame received from the transmitter 2201. More specifically, the receiver 2203 selects the format of a Block ACK frame based on the second information. The receiver 2203 selects the format of a bitmap included in the Block ACK frame for each TID, as in the embodiments described with reference to Figs. 14 to 21. If the data received by the receiver 2203 is transmitted via an A-MPDU, the A-MPDU includes at least one fragment, and the fragment numbers of the fragment are all 0, the receiver 2203 transmits a Block ACK frame including a bitmap in which each bit indicates whether each MSDU is received or not. A specific operation of the receiver 2203 is as in the embodiments described with reference to Figs. 15 to 16.

[0137] Data received by the receiver 2203 is transmitted via A-MPDU, and when the receiver 2203 receives all MPDUs contained in the A-MPDU, the receiver 2203 transmits a Block ACK frame including a bitmap in which each bit indicates whether each MSDU is received or not. The specific operation of the receiver 2203 is the same as the embodiment described with reference to Figs. 17 to 21.

[0138] As described above, the present invention has been described using wireless LAN communication as an example, but the present invention is not limited thereto and can be similarly applied to other communication systems such as mobile phone communication, etc. Also, although the method, device, and system of the present invention have been described in relation to specific embodiments, some or all of the components and operations of the present invention can be implemented using a computer system having a general-purpose hardware architecture.

[0139] The features, structures, effects, etc. described in the embodiments are included in at least one embodiment of the present invention, but are not necessarily limited to only one embodiment. The features, structures, effects, etc. exemplified in each embodiment may be combined or modified in other embodiments by a person having ordinary skill in the art to which the embodiment belongs. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

[0140] Although the present invention has been described with a focus on the embodiments, these are merely illustrative and do not limit the present invention, and a person having ordinary skill in the art to which the present invention pertains should understand that various modifications and applications not exemplified above are possible within the scope of the essential characteristics of the present invention. For example, each component specifically illustrated in the embodiments may be modified and implemented. Such modifications and differences in applications should be interpreted as being included in the scope of the present invention as defined in the appended claims. [Explanation of symbols]

[0141] 100 Stations 110 Processor 120 Transmitter / receiver 140 User Interface 150 display units 160 Memory 200 AP 210 Processor 220 Transmitter / receiver 260 Memory

Claims

[Claim 1] In a wireless communication terminal that transmits data, A transmitting / receiving unit; a processor; The processor, First information is inserted into a 2-bit field of an ADDBA (Add Block ACK) request frame, the first information indicating a fragmentation level to be used when the wireless communication terminal transmits data corresponding to a specific TID (Traffic Identifier) ​​to a recipient; The ADDBA request frame is transmitted to a receiver using the transceiver unit; receiving an ADDBA response frame from the recipient using the transceiver; obtaining second information from a 2-bit field of the ADDBA response frame, the second information indicating a fragmentation level of fragments that the receiver may receive when the receiver receives the data corresponding to the specific TID; fragmenting the data corresponding to the particular TID to a fragmentation level equal to or lower than the fragmentation level indicated by the second information; configured to transmit the fragmented data. A wireless communication terminal, The fragmentation levels are divided into four levels: Wireless communication terminal.

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