KR20060014875A - Method and apparatus for transmitting ack frame - Google Patents

Abstract

The present invention relates to a wireless communication method using more efficient burst ACK.

An ACK frame transmission method according to the present invention comprises receiving a frame from a transmitting device and storing identification information of the received frame, using the stored identification information and recording a set of bit pairs for each received frame Generating a first field, generating an ACK frame including the generated first field, and transmitting the generated ACK frame to a transmitting device, wherein the bit pair is whether the corresponding frame has been normally received; And a second bit for identifying whether the first bit indicates an acknowledgment for one frame or an acknowledgment for all fragments after the frame.

Wireless network, MSDU, Fragment, ACK

Description

Method and apparatus for transmitting ACK frame {Method and apparatus for transmitting ACK frame}

1 is a diagram illustrating a general burst ACK frame transmission scheme.

2 is a diagram illustrating a configuration of a delayed ACK frame according to the IEEE 802.15.3 standard.

3 is a diagram illustrating a configuration of a block ACK frame according to the IEEE 802.11e standard.

4 is a diagram illustrating a configuration of a burst ACK frame according to an embodiment of the present invention.

5 is a diagram illustrating the structure of the MAC header of the IEEE 802.11 series standard and the MAC header of the IEEE 802.15.3 standard.

6 to 10 are diagrams for describing how a burst ACK frame is determined according to various embodiments.

11 is a block diagram showing a configuration of a wireless device according to an embodiment of the present invention.

12 is a block diagram showing a detailed configuration of a burst ACK generation module.

13 is a diagram illustrating in detail the configuration of a MAC header according to a conventional IEEE 802.11 series standard.

14 is a diagram illustrating in detail the configuration of a MAC header according to the conventional IEEE 802.15.3 standard.

15 is a flowchart illustrating a burst ACK frame generation process according to an embodiment of the present invention.

16 is a flowchart illustrating a more detailed process for step S50 of FIG.

(Symbol description of main part of drawing)

100: burst ACK frame 200: wireless device

210: burst ACK generation module 211: generation control module

212: MPDU ID generation module 213: Bitmap generation module

214: pad generation module 220: MAC module

230: upper layer module 240: PHY module

250: memory 260: control unit

The present invention relates to a wireless communication method, and more particularly, to a wireless communication method using more efficient burst ACK (burst ACK).

Networks are becoming wireless and researches on effective transmission methods in wireless network environments have been required due to the increasing demand for large-capacity multimedia data transmission. Due to the nature of a wireless network in which multiple devices share and use a given radio resource, increasing competition is likely to waste valuable radio resources due to collisions during communication. In order to reduce such collisions and to transmit and receive data stably, a wireless LAN (wireless local area network) environment uses a competitive-based distributed coordination function (DCF) or a contention free point coordination function (PCF), and a wireless PAN. In a wireless personal area network environment, a time division scheme called channel time allocation is used.

In this way, data can be reliably transmitted and received in a wireless environment without collision, but while one device communicates, other devices within the same radio range have to wait, so the transmission rate decreases considerably as the number of devices increases. Done. Therefore, it is an important issue to ensure stable communication in a wireless network environment and to improve data transmission rate at the same time.

In order to improve the transmission rate, there is a method of reducing unnecessary overhead mainly in data to be transmitted, or a method of more efficiently allocating time between devices. The present invention is to reduce the traffic caused by the ACK frame more efficiently by simplifying the structure of the acknowledgment frame frequently used in the wireless network environment (wireless LAN, wireless PAN, etc.).

In general, when a device that transmits data (hereinafter referred to as a transmission device) transmits a data frame to a device that receives data (hereinafter, referred to as a receiver device), an ACK notifying when the receiving device receives the data frame properly. The frame is transmitted to the transmitting device.

The ACK frame includes an ACK frame immediately indicating that the frame has been properly received every time one frame is received, and an ACK frame that receives a plurality of frames for a predetermined number of times and indicates whether all the frames are received at once. There is a frame. The former ACK frame may be defined as an immediate ACK frame, and the latter ACK frame may be defined as a burst ACK frame. The present invention focuses on improving the structure of the burst ACK frame. have.

A general burst ACK frame is transmitted as shown in FIG. When the transmitting device transmits n data frames to the receiving device, the receiving device can reduce traffic as compared to sending an ACK frame immediately by sending ACK frames for the n data frames at once.

In fact, as a concept of such burst ACK frame, a delayed ACK frame is used in the Institute of Electrical and Electronics Engineers (IEEE) 802.15.3 wireless PAN standard, and a block ACK frame (Block) in the IEEE 802.11e wireless LAN standard. ACK frame).

2 shows a configuration of a delayed ACK frame 10 according to the IEEE 802.15.3 standard. In IEEE 802.15.3, the frame format is generally displayed from the right side, so the MAC header 11 is displayed on the right side. The delayed ACK frame 10 includes a MAC header 11, a Max burst field 12 indicating the number of frames having the maximum MAC frame size among the frames waiting for the delayed ACK, and a maximum that can be processed simultaneously with the delayed ACK. Max frames field 130 indicating the number of frames, n MPDU (MAC Protocol Data Unit) ID block fields 15, 16, etc., and an FCS field 17 for calculating an error checksum. Can be.

Each of the MPDU ID block fields (15, 16, etc.) is incremented by one each time a MSDU (MAC Service Data Unit) is received from a higher layer (e.g., a Logical Link Control (LLC) layer) at the MAC side of the transmitting device. The MSDU number field 18, which records the MSDU number (that is, the identification number of the MSDU), is recorded, and the fragment number field 19, in which the fragmentation order is recorded when the MSDU is fragmented and transmitted. The receiving device records the MSDU number and the fragment number with respect to the data received by the receiving device and transmits the data to the transmitting device so that the transmitting device knows which data (MSDU itself or some fragment of the MSDU) was not transmitted properly. Get to know. Thereafter, the transmitting device retransmits only the data that is not properly transmitted to the receiving device.

As shown in FIG. 2, in the IEEE 802.15.3 standard, 9 bits are allocated to the MSDU number field 18 and 7 bits are allocated to the fragment number field 19. Thus, one MPDU ID block field 15, 16, 2 octets are allocated.

3 shows a configuration of a block ACK frame 20 according to the IEEE 802.11e standard. The block ACK frame 20 includes a MAC header 21, a BA Control field 22 for controlling the operation of the block ACK frame, and a Block ACK Starting Sequence Control field in which the fragment number and sequence number of the first MPDU are recorded. 23), a Block ACK Bitmap field 24 in which 'acknowledgement information' (information indicating whether the specific data has been received correctly) for subsequent MPDUs are recorded in order, and an FCS field 25 for calculating an error checksum. It can be configured as.

Since 128 bytes are allocated to the Block ACK Bitmap field 24, when two bytes are allocated to one MSDU, acknowledgment information of up to 64 MSDUs can be recorded. In this way, two bytes are allocated to one MSDU. In IEEE 802.11e, up to 16 fragments can be fragmented in one MSDU, so that the maximum number of fragments (16 × 1 bit) can be obtained. 2 bytes are allocated. Therefore, even if the fragment is not actually fragmented or fragmented less than 16, two bytes are uniformly allocated, and thus it is not efficient to indicate the acknowledgment information in one bit.

As shown in FIG. 2 or FIG. 3, when two bytes are used to represent one MSDU, there is a problem that the size of the burst ACK frame becomes larger than necessary. If n data is transmitted and a burst ACK frame is received, the payload of the burst ACK frame will be 2n bytes or more. Therefore, as the number of transmissions of data increases, the size of the burst ACK frame increases, thereby causing unnecessary traffic in the wireless network environment.

Therefore, it is necessary to reduce the traffic due to the ACK frame by developing a burst ACK frame having a smaller size while still performing the function of the existing burst ACK frame.

The present invention has been made in view of the above problems, and an object thereof is to provide a method for reducing overhead of a burst ACK frame.

Another object of the present invention is to provide a method capable of displaying reception acknowledgment information in two bits for one MSDU.

In order to achieve the above object, an ACK frame transmission method for receiving a plurality of frames from the transmitting device and acknowledgment with a single ACK frame, (a) receiving a frame from the transmitting device and of the received frame Storing identification information; (b) using the stored identification information, recording a set of bit pairs for each received frame to generate a first field; (c) generating an ACK frame including the generated field; And (d) transmitting the generated ACK frame to the transmitting device, wherein the bit pair includes a first bit for confirming whether the corresponding frame is normally received, and the first bit is received for the corresponding frame. And a second bit for distinguishing whether to indicate acknowledgment or acknowledgment for all fragments after the frame.

In order to achieve the above object, an ACK frame transmitting apparatus for receiving a plurality of frames from a transmitting device and acknowledgment with one ACK frame, comprising: first means for receiving a frame from the transmitting device; Second means for storing identification information of the received frame; Third means for generating a first field by recording the set of bit pairs for each received frame using the stored identification information, and generating an ACK frame including the generated field; And fourth means for transmitting the generated ACK frame to the transmitting device, wherein the bit pair includes a first bit for confirming whether the corresponding frame is normally received, and the first bit confirms receipt for the corresponding frame. It is configured as a second bit to distinguish whether or not to indicate whether or not to indicate acknowledgment for all fragments after the frame.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

4 is a diagram illustrating a configuration of a burst ACK frame 100 according to an embodiment of the present invention. The burst ACK frame 100 may be composed of a MAC header 110 and payload regions 120, 130, and 140. The MAC header 110 may have the same configuration as the MAC header of the conventional IEEE 802.11 series standard, such as 110A of FIG. 5, or the MAC header of the conventional IEEE 802.15.3 standard, such as 110B of FIG. 5.

The payload region may include an MPDU ID field 120, a Bitmap field 130, and a pad field 140. In the MPDU ID field 120, identification information of the first frame of a frame (hereinafter, referred to as a 'target frame') to which an ACK response is to be recorded is recorded, which is again referred to as an MSDU number field 121 and a fragment number field ( 122). Since the burst ACK frame 100 according to the present invention responds to not only the received frame but also the entire transmission frame including the unreceived frame, the burst frame corresponds to the entire transmission frame (transmission frame requiring ACK) within a predetermined period. Limited).

The MSDU number field 121 records the MSDU number of the first frame of the target frame, and the Fragment number field 122 records the Fragment number of the first frame of the target frame. The MSDU number and the fragment number can be known by looking at the MAC header of the received target frame.

In the bitmap field 130, a pair of ACK bits and a type bit (hereinafter referred to as a bit pair) for a target frame are sequentially recorded. The number of bit pairs (m) is the same as the total number of MSDUs when the minimum is m, and the maximum If is equal to the total number of fragments.

 As will be appreciated, the target frame may be composed of one MSDU when the fragmentation is not performed, and some fragments of the MSDU when the fragmentation is performed.

In the bitmap field 130, a bit for confirming whether a corresponding frame is normally received is recorded in the ACK bit, and may be recorded as 1 if normally received or 0 otherwise. In addition, the Type bit distinguishes whether the ACK bit indicates an acknowledgment for the corresponding frame (MSDU or fragment) (e) or whether the latter indicates an acknowledgment for all fragments after the current fragment in the MSDU (the latter). Bit information is recorded. The Type bit may be written as 0 in the former and 1 in the latter.

The pad field 140 is a variable bit and filled with dummy bits (eg, 0). Since the Bitmap field 130 is a bit unit, this field 140 is used to fill a predetermined number of dummy bits, for example, a predetermined number of zeros into byte to octet units. Therefore, the sum of the sizes of the Bitmap field 130 and the Pad field 140 will always be in bytes. However, since the pad field 140 is not an essential item for defining a protocol according to the present invention, the pad field 140 may be omitted.

6 to 10 are diagrams for describing how the burst ACK frame 100 is determined according to various embodiments. Here, [A: B] is an indication for identifying a frame, where A is a sequence number (hereinafter referred to as MSDU sequence number) assigned to an MSDU number transmitted by a transmitting device, and B is a fragment number (starting from 0). . For example, if the transmitting device transmits a frame whose MSDU number is 1234 to 1237, the MSDU sequence number is assigned from 1 to 4, respectively. The MSDU sequence number is based on the MSDU number transmitted by the transmitting device, and not based on the MSDU number received and stored by the receiving device. If the transmitting device transmits a frame whose MSDU number is 1234 to 1237, but the receiving device receives only frames 1235 and 1237, the MSDU number is sequentially assigned to all of 1234 to 1237.

6 illustrates the structure of a burst ACK frame 100 when all of [1: 0], [2: 0], [3: 0], and [4: 0] are normally received. fragmentation) does not occur at all. In the MPDU ID field 120, an MSDU number (= 1) and a fragment number (= 0) of [1: 0] are recorded. In the bitmap field 130, bit pairs consisting of ACK bits and Type bits for the target frame are sequentially recorded. However, since only the Bitmap field 130 is in a byte unit, a separate pad field is not necessary. In this case, the order refers to the order according to the MSDU number and the fragment number, not to the order in which the frames are received. This is because the first transmitted frame may be received later for some reason.

Since [1: 0], [2: 0], [3: 0], and [4: 0] were all received normally, the first bit of the bit pair is filled with one. The second pair of bits (indicated by X) can be filled with either zero or one. This is because the corresponding MSDU is completed in the frame, and may be marked as 1, while it may also be indicated as 0 because it is an indication of whether an ACK is received for one frame. Moreover, there is no possibility of confusion because which MSDU is fragmented because the sending device and the receiving device know each other by sharing information about it. However, it would be more desirable to fill in 1 in terms of clarifying the meaning of completion in one MSDU. X is interpreted as having the same meaning as in the present embodiment.

7 shows the structure of a burst ACK frame 100 when all of [1: 0], [2: 0], [2: 1], [3: 0], and [4: 0] are normally received. This is the case where fragmentation occurs in the second MSDU. As in FIG. 6, the MSDU number (= 1) and the fragment number (= 0) of [1: 0] are recorded in the MPDU ID field 120. In the bitmap field 130, bit pairs consisting of ACK bits and Type bits for the target frame are sequentially recorded.

Since [1: 0], [2: 0], [2: 1], [3: 0], and [4: 0] were all received successfully, the first bit of the bit pair is filled with 1, of which [1: 0], [3: 0], and [4: 0] are complete frames, so the second bit is filled with X. However, since [2: 1] with the same MSDU number and different Fragment number exists after [2: 0], the second bit of the pair of bits for [2: 0] is represented by 1 and after [2: 0] All of the fragments indicate that the fragment is received normally.

It is preferable to display the fragmented MSDUs at once, but in the same situation, when the MSDU is fragmented as shown in FIG. 8, a method of displaying the fragments for each fragment can also be considered.

9 shows that the transmitting device has transmitted [1: 0], [2: 0], [2: 1], [2: 2], and [3: 0], but the receiving device has [1: 0], [2] The structure of the burst ACK frame 100 is shown when only: 0] and [3: 0] are normally received. Here, it can be seen that the second MSDU is divided into three fragments. In the MPDU ID field 120, an MSDU number (= 1) and a fragment number (= 0) of [1: 0] are recorded. In the bitmap field 130, bit pairs consisting of ACK bits and Type bits are sequentially recorded for all target frames transmitted by the transmitting device.

Since [1: 0] and [3: 0] are all received normally, the first bit of the bit pair is filled with 1, and the second bit is filled with X because it is a complete frame. However, [2: 0] is normally received, but since there is a fragment thereafter, '10' is recorded in the corresponding position only for acknowledgment of the corresponding frame, that is, the fragment. However, since [2: 1] and [2: 2] were not normally received, the first bit of the bit pair corresponding to the position of [2: 1] is represented by 0 representing these two frames. And, the second bit is indicated as 1, which means that the first bit is the ACK bit after the corresponding position, that is, for [2: 1] and [2: 2].

By the way, when the receiving device receives only [2: 0], it is a problem how to know whether [2: 1] and [2: 2] exist. However, this can be seen by looking at the MAC header of [2: 0]. A more detailed description thereof will be described later with reference to FIGS. 13 and 14.

10 shows that the transmitting device has transmitted [1: 0], [2: 0], [2: 1], [2: 2], and [3: 0], but the receiving device has [1: 0], [3]. : 0] shows the structure of the burst ACK frame 100 when normally received only. Here, since the receiving device has not received any data regarding the second MSDU, it cannot be known that it is composed of three fragments. However, since [1: 0] and [3: 0] were received, it can be seen that the frame for the second MSDU was not transmitted.

In the MPDU ID field 120, an MSDU number (= 1) and a fragment number (= 0) of [1: 0] are recorded. In the bitmap field 130, bit pairs consisting of ACK bits and Type bits are sequentially recorded for all target frames transmitted by the transmitting device.

Since [1: 0] and [3: 0] are all received normally, the first bit of the bit pair is filled with 1, and the second bit is filled with X because it is a complete frame. However, when the frame having the MSDU of 1 and the frame of the 3 are received, it can be seen that the frame having the MSDU of 2 was also transmitted but was not received due to an error. As such, the frame for the second MSDU was not received at all, but by filling the first bit with 0 at the position of [2: 0] and the second bit with 1, all fragments after [2: 0] are not received. It can indicate that it was not.

11 is a block diagram illustrating a configuration of a wireless device 200 according to an embodiment of the present invention, which transmits the same burst ACK frame 100. The wireless device 200 includes a burst ACK generation module 210, a MAC module 220, a higher layer module 230, a PHY module 240, a memory 250, and a control unit 260. Can be configured.

The burst ACK generation module 210 reads MPDU ID information as identification information of the frame from the header information of the received data frame and uses the information to payload the burst ACK frame 100 according to the present invention. ) The burst ACK generation module 210 has a detailed structure as shown in FIG. 12 again. That is, the burst ACK generation module 210 may include a generation control module 211, an MPDU ID generation module 212, a bitmap generation module 213, and a pad generation module 214.

The generation control module 211 checks a condition for generating a burst ACK frame 100 for a predetermined number of frames received from a specific transmitting device (hereinafter referred to as an 'ACK generation condition'). The MPDU ID information included in the MAC header of the frame received from the specific transmitting device is received from the MAC module 220 and stored in the memory 250. When the condition is completed, the MPDU ID generation module 212, the bitmap generation module 213, and the pad generation module 214 generate the payload of the burst ACK frame 100 using the stored MPDU ID information. Do it.

Here, the MPDU ID information includes 'MSDU number' indicating a unique serial number for the MSDU of the received frame and 'Fragment number' indicating the order of fragments. The MPDU ID information is also shown in the MAC Header 110A according to the IEEE 802.11 series standard as shown in FIG. 13 and also in the MAC Header 110B according to the IEEE 802.15.3 standard as shown in FIG.

In the MAC Header 110A of FIG. 13, the Sequence Control field 112 is divided into a Fragment Number field 114 and a Sequence Number field 115. In the Fragment Number field 114, a 'Fragment Number' is recorded. 'MSDU Number' is recorded in the Number field 115. Therefore, the MSDU ID information can be known by reading the Sequence Control field 112.

The Frame Control field 111 includes a More Frag bit 113, in which bit information indicating whether the current frame is the last fragment is recorded. If the bit is 1, the later fragment is present. If the bit is 0, the current frame is the last fragment. In the case of FIG. 9, only [2: 0] is received and it is not known that the entire fragment is three, but it can be seen that [2: 0] is not the final fragment.

In the MAC Header 110B of FIG. 14, the Fragmentation Control field 112 is divided into an MSDU number field 117, a Fragment number field 118, and a Last fragment number field 119. Therefore, the MSDU ID information can be known by reading the Fragmentation Control field 112. Unlike in FIG. 12, however, since the last fragment number is recorded in the last fragment number field 119 in every frame composed of fragments, even when only [2: 0] is received in the case of FIG. 9, [2: 1] and [ 2: 2].

12 again, the condition that the generation control module 211 checks is that, when the transmitting device transmits the target frame to the receiving device, some bits (hereinafter, referred to as 'request bits') in the MAC header requesting a burst ACK frame. It can be based on whether it is ON. That is, each time the target frame is received, the value of the 'request bit' of the frame is read, and if the value is a bit indicating OFF (= 0), the ACK generation condition is not achieved, and the bit indicating the value is ON. If (= 1), it is determined that the ACK generation condition has been achieved.

If the sending device sends [1: 0], [2: 0], [3: 0], and the request bit is set to ON in [3: 0], the receiving device is set to [1: 0], [ 2: 0], the receiving device will not generate a burst ACK frame since the ACK generation condition has not been achieved. The transmitting device will then consider that there is a transmission error if a burst ACK frame is not received within a certain time period and send [3: 0] again with the request bit set to ON.

In the above description, the ACK generation condition is determined by the transmitting device. However, the ACK generation condition may be satisfied when the number of target frames is received.

 The MPDU ID generation module 212 uses the MSDU ID information stored in the memory 250 to determine the MPDU ID field 120, that is, the MSDU number field 121 of the first frame of the target frame, and the fragment of the first frame of the target frame. Record the number field 122.

The bitmap generation module 213 sequentially records the bit pairs for the target frame in addition to the MPDU ID field 120. In the first bit (ACK bit), a bit to check whether the frame indicated by the current pair of bits is normally received (1, or 0 if it is normally received) is recorded.In the second bit (Type bit), the first bit is acknowledged for the corresponding frame. Bit information is discriminated whether to indicate (recording as 0) or indicating acknowledgment (recording as 1) for all fragments after the current fragment in one MSDU.

The pad generation module 214 fills the remaining bits with zeros to make the byte unit when the size of the bitmap does not become the byte unit.

Referring back to FIG. 11, the MAC module 220 manages the operation in the MAC layer. That is, the MSDU is received from the upper layer module 230 and the MAC header of FIG. 13 or 14 is attached thereto, and the result is transmitted to the PHY module 240. In addition, the MAC module 220 receives the payload of the burst ACK frame from the burst ACK generation module 210, and similarly attaches the MAC header to the PHY module 240.

In addition, when receiving a frame transmitted from another device from the PHY module 240, the MAC header is read here, the MAC header is removed, and the result is transmitted to the upper layer module 230. The MPDU ID information read from the MAC header is transmitted to the burst ACK generation module 210.

The higher layer module 230 generates an MSDU and delivers the MSDU to the MAC module 220, and receives data from which the MAC header is removed from the MAC module 220. The upper layer module 230 manages a network layer above the LLC layer (Logical Link Layer).

The PHY module 240 manages the operation in the physical layer. That is, the MAC module 220 receives the MPDU (MAC Protocol Data Unit) from the MAC module 220 to generate a PPDU (Packet Protocol Data Unit), and generates and transmits a radio signal including the same. In addition, after receiving and processing the signal transmitted through the wireless medium and delivers it to the MAC module 220. The PHY module 240 may be further subdivided into a base band processor and a radio frequency (RF) module.

The memory 250 stores the MPDU ID information for the received frame and provides this information when requested by the burst ACK generation module 210.

The control unit 260 controls the operation of other modules in the wireless device 100, which may be implemented as a central processing unit (CPU), a microcomputer, or the like.

In the description so far, the term "module" refers to a software component or a hardware component such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). Means a module plays some role. However, modules are not meant to be limited to software or hardware. The module may be configured to be in an addressable storage medium and may be configured to execute one or more processors. Thus, as an example, a module may include components such as software components, object-oriented software components, class components, and task components, processes, functions, and the like. functions, properties, procedures, sub-routines, segments of program code, drivers, firmwares, microcomputers Includes micro-codes, circuits, data, databases, data structures, tables, arrays, and variables do. The functionality provided within the components and modules may be combined into a smaller number of components and modules or further separated into additional components and modules. In addition, the components and modules may be implemented to execute one or more computers in a communication system.

15 is a flowchart illustrating a process of generating a burst ACK frame 100 according to an embodiment of the present invention.

First, until the ACK generation condition is completed (NO in S20), a 'target frame' is received through the PHY module 240 (S10), and the generation control module stores MPDU ID information of the received target frame. Repeat (S25). The MPDU ID information includes the MSDU number and the fragment number of the corresponding target frame.

If the generation control module 211 determines whether the ACK generation condition is completed (Yes in S20), the generation control module 211 controls to generate the payload of the burst ACK frame 100. The process of generating the payload is performed in steps S30 to S69.

First, the MPDU ID generation module 212 generates the MPDU ID field 120 by recording the MSDU number field 121 and the fragment number field 122 of the first frame among the target frames stored in the memory 250 (S40). .

The bitmap generation module 213 generates the bitmap field 130 by sequentially recording the bit pairs for the target frame in addition to the MPDU ID field 120 (S50). A more detailed process for step S50 will be described later in the description of FIG. 16.

If the size of the generated Bitmap field 130 is in units of bytes (YES in S68), it is not necessary to generate the Pad field 140, but otherwise, a Pad field having a continuous 0 value of a predetermined bit 140 is successively added to the Bitmap field 130. The number of bits having the consecutive zero values is the number of the bitmap field 130 and the pad field 140 to be in a byte unit.

The MAC module 120 attaches the MAC header to the payload of the burst ACK frame 100 generated in S50 or S69 to generate the burst ACK frame 100 (S70). The PHY module 140 transmits the burst ACK frame 100 generated to the device that transmitted the target frame through the wireless medium (S80).

FIG. 16 is a flowchart illustrating step S50 of FIG. 15 in more detail.

First, 'MSDU sequence number' is assigned to the MSDU number stored in the memory 250 (S51). For example, if the stored MSDU number is 1234 to 1237, the MSDU number k of the MSDU number is 1 to 4 in order. If the stored MSDU numbers are not contiguous, the MSDU sequence number (k = 3) is assigned to 1235 which does not exist even in the case of 1234, 1236, 1237, as well as the case where all are properly received.

Next, k is set to 1 as an initial value and the last MSDU sequence number is set to N (S52).

Since there may be a reception error, the MSDU number stored in the memory 250 does not exist for every MSDU sequence k. Therefore, it is determined whether the MSDU number exists for the k-th MSDU sequence number (S53), and if it does not exist (NO in S53), the bit pair is recorded as '01' in the Bitmap field 130 (S59).

If it is present, it is determined whether the k-th MSDU is fragmented (S54). If it is not fragmented (NO in S54), the bit pair is recorded as '1X' in the Bitmap field 130. Here, X means that any value of 1 or 0 may be recorded.

If it is fragmented (YES in S54), the fragment numbers of all the stored fragments corresponding to the kth MSDU are read (S55). The bit pairs are sequentially recorded in the Bitmap field 130 for each of the 'fragment sequence numbers' smaller than the maximum fragment number among the stored fragment numbers (S56). Like the MSDU sequence, the fragment sequence number is sequentially assigned based on the frame transmitted by the transmitting device.

For example, suppose that [2: 0], [2: 1], [2: 2], and [2: 3] were sent, but only [2: 1] and [2: 3] were received. Since the fragment number of the stored fragment is 1, 3, the maximum fragment number is 3. Since the 'fragment sequence number' smaller than 3 means 0, 1, and 2, when the bit pairs are sequentially written in the bitmap field 130, '00', '10', and '00' are obtained.

Next, if the maximum fragment number is the same as the final fragment number (YES in S57), the bit pair is recorded as '1X' in the Bitmap field 130. As described above, the maximum fragment number refers to the maximum value of the fragment numbers stored in the memory 250, and the final fragment number refers to the final fragment number of the target frame transmitted by the transmitting device. Whether the maximum fragment number is the final fragment number can be known by referring to the More Frag field 113 in FIG. 13 or the Last fragment number field 119 in FIG.

In the case of NO in step S57, the bit pair for the fragment having the maximum fragment number in the Bitmap field 130, that is, '10' is recorded (S61), and the bit pair for all subsequent fragment numbers is '01'. Collectively record as (S62).

After performing step S58, step S59, step S60, or step S66, if k equals to N, the recording of the bitmap field 130 is completed since the completion of the step. Otherwise, the process returns to step S53 after incrementing k by one.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

According to the present invention, there is an effect of reducing the overhead of transmitting a burst ACK frame.

In addition, according to the present invention, due to the overhead reduction of the ACK frame has the effect of improving the total data rate in the entire wireless network.

The burst ACK frame format according to the present invention can be applied to a block ACK frame in the IEEE 802.11e standard or a delayed ACK frame in the IEEE 802.15.3 standard.

Claims (15)

An ACK frame transmission method for receiving a plurality of frames from a transmitting device and acknowledgment with one ACK frame thereto, (a) receiving a frame from the transmitting device and storing identification information of the received frame; (b) using the stored identification information to generate a first field by recording a set of bit pairs for each received frame; (c) generating an ACK frame including the generated first field; And (d) sending the generated ACK frame to the transmitting device, The bit pair may include a first bit for confirming whether the corresponding frame is normally received, And a second bit for distinguishing whether the first bit indicates an acknowledgment for one frame or an acknowledgment for all fragments after the frame. The method of claim 1, wherein step (c) (c1) generating a second field for recording first identification information of the identification information. The method of claim 2, wherein step (c) (c2) if the first field is not in a byte unit, adding a predetermined dummy bit to make it in a byte unit. The method of claim 3, wherein the identification information And a MSDU number and a Fragment number of the received frame. The method of claim 4, wherein And the first identification information is identification information with the first fragment number among the identification information with the MSDU number leading. The method of claim 1, The first bit is recorded as 1 when the frame is normally received and 0 otherwise. Assuming that the second bit is written as 1 if the first bit indicates an acknowledgment for one frame, the step (b) is performed otherwise. (b1) if the MSDU number does not exist for a specific MSDU number, recording a bit pair as '01', and if present, determining whether the MSDU of the sequence is fragmented; And (b2) if the MSDU is not fragmented, recording a bit pair as '1X', X is any one of 1 or 0, ACK frame transmission method. The method of claim 6, wherein when the MSDU is fragmented, step (b) (b3) sequentially recording the bit pairs for each of the Fragment sequence numbers smaller than the maximum Fragment number; (b4) if the maximum fragment number is the same as the final fragment number, further comprising: recording a bit pair as '1X'. 8. The method according to claim 7, further comprising the step of writing a bit pair as '10' and subsequent bit pairs as '01' if the maximum fragment number is not equal to the final fragment number. The method of claim 1, wherein step (b) ACK frame transmission method performed when an ACK frame transmission request is received from the transmitting device. An ACK frame transmission apparatus for receiving a plurality of frames from the transmitting device and to respond to the response as one ACK frame, First means for receiving a frame from the transmitting device; Second means for storing identification information of the received frame; Third means for generating a first field by recording the set of bit pairs for each received frame using the stored identification information, and generating an ACK frame including the generated first field; And Fourth means for transmitting the generated ACK frame to the transmitting device, The bit pair may include a first bit for confirming whether the corresponding frame is normally received, And a second bit for discriminating whether the first bit indicates an acknowledgment for one frame or an acknowledgment for all fragments after the frame. The method of claim 10, wherein the third means And a second field for recording first identification information of the identification information. The method of claim 11, wherein the third means And when the first field is not in bytes, adds a predetermined dummy bit to make it in bytes. The method of claim 12, wherein the identification information And an MSDU number and a Fragment number of the received frame. The method of claim 13, And the first identification information is identification information of which the fragment number is the earliest among identification information of which the MSDU number is the earliest. The method of claim 10, wherein the third means And receiving an ACK frame transmission request from the transmitting device.

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