KR100631742B1 - AC frame transmission method and device - Google Patents

Abstract

The present invention relates to a more efficient block ACK method and apparatus in communication in a wireless LAN environment.

The block ACK transmitting apparatus according to the present invention receives a frame from the transmitting station and at least identifies the identification number of the received data frame and, if the data frame is a fragmented frame, the fragment number and the final fragment number of the data frame. And storing a set of bit pairs for each of the received data frames using the stored information, wherein the bit pairs include a first bit for confirming whether the corresponding frame is normally transmitted, and the first bit. Generating an ACK frame comprising the set of recorded bit pairs, and transmitting the generated ACK frame to the transmitting station, configured as a second bit representing a range of data frames represented by a bit; Consists of steps.

Wireless network, MSDU, Fragment, ACK

Description

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

1 is a view showing the configuration of a conventional block ACK request frame 10.

2 is a view showing the configuration of a conventional block ACK frame 20.

3 shows a simplified block ACK mechanism.

4 is a diagram showing the configuration of a data frame 50 according to an embodiment of the present invention.

5 is a diagram illustrating a configuration of a block ACK frame 100 according to an embodiment of the present invention.

6 to 11 are diagrams for describing how a block ACK frame 100 is configured according to various embodiments.

Fig. 12 is a diagram showing the configuration of the Block Ack Bitmap field 170 when using the 1 bit mode.

FIG. 13 is a diagram showing an example in which the case of FIG. 10 is expressed in 1-bit mode; FIG.

14 is a block diagram showing the configuration of a wireless station 200 according to an embodiment of the present invention.

15 is a flowchart illustrating overall operation according to an embodiment of the present invention.

(Symbol description of main part of drawing)

50: data frame 100: block ACK frame

150: BA Control field 151: Bitmap Length field

152: Mode Selection field

160: Block Ack Starting Sequence Control field

161: Fragment Number field 162: Starting Sequence Number field

170: Block Ack Bitmap field 171, 172, 173: bit pair field

171a: ACK bit 171b: MSDU bit

174: Padding fields 175, 176, 177: ACK bit

MAC Header: 190 200: Wireless Station

210: block Ack generation module 220: MAC header reading module

230: transmission and reception module 240: control module

250 memory

The present invention relates to a wireless communication method, and more particularly, to a more efficient block acknowledgment (ACK) method and apparatus for communication in a wireless LAN environment.

As the market for wireless LANs gradually grows and its application ranges are diversified, the bandwidth of the wireless LANs required is increasing day by day. However, it was difficult to satisfy the WLAN bandwidth based on the existing IEEE 802.11 series (a, b, g, etc.). Nevertheless, as demand increases, the IEEE has begun standardizing new wireless LANs.

To meet these demands, the IEEE 802.11n Task Group is implementing a new type of WLAN standardization with bandwidths of 100 Mbps or more. IEEE 802.11n is one of the wireless LAN standards applying MIMO (Multi Input Multi Output) technology based on the IEEE 802.11e-based QoS enhancement technology. IEEE 802.11n can coexist with existing WLAN and communicate if necessary. In addition, various functions have been added, one of which is block transmission (meaning transmission of data frames transmitted continuously without receiving an ACK).

Since the channel is not reliable due to the characteristics of the WLAN, an acknowledgment frame is generally used to confirm a data transmission result. However, in IEEE 802.11n, a block ACK request frame and a block ACK frame (block ACK frame) are used as a result of block transmission. Here, the block ACK frame may include transmission confirmation results for up to 64 MAC Service Data Units (MSDUs) and up to 1024 fragmented frames. However, the block ACK frame is inefficient because it has a fixed size of 152 bytes regardless of the number of block transmissions transmitted.

In the block ACK scheme, a block ACK request frame and a block ACK frame are used. The conventional block ACK request frame 10 has the configuration shown in FIG. The type of the frame 10 is control, the subtype is '1000', and includes a BA control field 11 and a Block ACK Starting Sequence field 12. The BA control field 11 is further subdivided into a Reserved field 11a and a TID field 11b, and the Block ACK Starting Sequence field 12 is further subdivided into a Fragment Number field 12a and a Starting Sequence Number field 12b. do.

On the other hand, the conventional block ACK frame 20 has a configuration shown in FIG. The type of the frame 20 is control and the subtype is 1001. The block ACK frame 20 includes a BA control field 21, a Block ACK Starting Sequence field 22, and a Block ACK Bitmap field including a result of transmission confirmation of previously transmitted blocks. And (23).

After the receiver successfully receives the block ACK request frame transmitted by the originator, the receiver receives the block ACK bitmap field 23 in the block ACK frame 20 and confirms the result of the data transmission by the block transmission. ) And send it to the sender. In general, an originator is used to mean a station transmitting data, and a recipient is used to mean a station receiving data.

The Block ACK Bitmap field 23 has a fixed length of 128 bytes and is configured to represent 64 MSDUs. That is, 2 bytes are allocated per MSDU, which can represent 16 fragments. The transmission confirmation result of up to 64 MSDUs and up to 1024 fragments may be represented by bitmaps B0 to B1023 of 1024 bits.

As such, when the conventional block ACK frame 20 is used, transmission confirmation is always performed using a fixed-length bitmap, and thus there is a simple side of writing and reading the frame. However, in a wireless network environment where the radio channel resources are insufficient, it may act as a factor that inhibits the efficient use of the channel.

In practice, one MSDU can consist of up to 16 fragments, but in most cases data is transmitted in a single MSDU without fragmentation. However, since the conventional Block ACK frame 20 is always configured to record 64 MSDUs, that is, 1024 fragments, a large number of wasted areas occur in the frame 20. In addition, since a small size block transmission is always transmitted including a fixed size bitmap, the channel occupancy time is increased, resulting in inefficiency of channel usage.

If the receiver, which has received 64 MSDUs that are not fragmented at all, transmits the conventional block ACK frame 20 for this, the frame 20 includes meaningless information of (1024-64) bits. Therefore, if only the efficiency of the bitmap included in the frame 20 is considered, this results in a waste of about 94%.

Therefore, it is necessary to develop a configuration of a block ACK frame having a smaller size while performing a conventional function as it is, so that the traffic of wireless communication is reduced.

The present invention has been made in accordance with the above-described needs, and an object thereof is to provide a method and apparatus for more efficiently utilizing channel resources in a wireless communication environment.

To this end, an object of the present invention is to provide a method and apparatus for reducing the overhead of a block ACK frame.

In order to achieve the above object, an ACK frame transmission method for receiving at least one data frame from a transmitting station according to the present invention and acknowledgment with one ACK frame, (a) receiving a frame from the transmitting station And storing at least an identification number of the received data frame and a fragment number and a final fragment number of the data frame if the data frame is a fragmented frame; (b) recording a set of bit pairs for each of the received data frames using the stored information, wherein the bit pairs include a first bit for confirming whether the corresponding frame is normally transmitted; Configured as a second bit indicating a range of data frames to indicate; (c) generating an ACK frame including the recorded set of bit pairs; And (d) transmitting the generated ACK frame to the transmitting station.

In order to achieve the above object, according to the present invention, an ACK frame transmission method for receiving at least one data frame from a transmitting station and acknowledgment with one ACK frame, (a) receiving a frame from the transmitting station Storing at least an identification number of the received data frame and a fragment number and a final fragment number of the data frame if the data frame is a fragmented frame; (b) successively writing bits that confirm whether each of the received data frames has been normally transmitted using the stored information; (c) generating an ACK frame comprising the recorded bits; And (d) transmitting the generated ACK frame to the transmitting station.

In order to achieve the above object, an ACK frame transmitting apparatus for receiving at least one frame from the transmitting station according to the present invention and acknowledgment with a single ACK frame, receiving the frame from the transmitting station and at least the receiving Means for storing a fragment number of the data frame and a fragment number and a final fragment number of the data frame if the data frame is a fragmented frame; Means for recording a set of bit pairs for each of the received data frames using the stored information, wherein the bit pairs include: a first bit for confirming whether the corresponding frame is normally transmitted; and a data frame represented by the first bit. Said means configured as a second bit representing a range of; Means for generating an ACK frame containing the recorded set of bit pairs; And means for transmitting the generated ACK frame to the transmitting station.

In order to achieve the above object, an ACK frame transmitting apparatus for receiving at least one data frame from the transmitting station according to the present invention and acknowledgment with a single ACK frame, which receives the frame from the transmitting station and at least the Means for storing an identification number of a received data frame and a fragment number and a final fragment number of the data frame if the data frame is a fragmented frame; Means for successively recording bits that confirm whether each of the received data frames has been successfully transmitted using the stored information; Means for generating an ACK frame comprising the recorded bits; And means for transmitting the generated ACK frame to the transmitting station.

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 will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. 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.

The block ACK mechanism makes it possible to transmit a block of data (a collection of data frames transmitted in succession without receiving an ACK) having a time interval equal to the short interframe space (SIFS). The mechanism improves channel efficiency by replacing multiple ACKs with one frame (block ACK frame). There are two types of block ACK mechanisms, 'immediate' and 'delayed'. Immediate type block ACK is suitable for an environment requiring high bandwidth and low traffic latency, and delayed type block ACK is suitable for an environment that can tolerate some latency.

The block ACK mechanism is started by sending an ADDBA request frame as shown in FIG. The block of data is then sent from the originator to the recipient. The time interval between QoS data is maintained in SIFS. Thereafter, as the sender makes a Block ACK request (BlockAckReq) to the receiver, the receiver transmits a Block ACK frame to the sender.

Finally, the sender can terminate the entire process by sending a DELBA request to the receiver. Although the example of FIG. 3 includes a setup process and a release process, this is only an example and a setup process and a release process are not necessarily required to carry out the present invention.

4 is a diagram illustrating a configuration of a data frame 50 according to an embodiment of the present invention. The data frame 50 includes a Frame Control field, a Duration / ID field, four Address fields (Address 1, Address 2, Address 3, and Address 4), and a Sequence Control field as in the conventional IEEE 802.11a. It may be configured to include a MAC header, a frame body, and an FCS field. Among these, the FCS field is a field for 32-bit cyclic redundancy checking (CRC) error checking and is not an essential component for implementing the present invention.

The frame control field 51 includes at least a type field 111 and a subtype field 112. In order to use the bitmap scheme composed of bit pairs or bitmap scheme composed of ACK bits, which will be described later in the present invention, when the MSDU composed of fragmented MPDU (MAC Protocol Data Unit) is transmitted, the final fragment number is transmitted to the receiver. Let's pass the Last Fragment Number. Here, the last fragment number refers to the total number of fragments of the MSDU currently transmitted, that is, the serial number of the last fragment of all fragments.

Such a final fragment number may be transmitted in various ways, but in the present invention, the Type field 52 and the Subtype field 53 are used as an example.

In the conventional Type field, a type value of a frame is recorded. The value may have a value of '00', '01', and '10', in order of a 'Management' frame type and a 'Data' frame type, respectively. , Refers to the 'Control' frame type. And the value '11' is reserved. The present invention uses the above reserved values in order to maintain compatibility with conventional standards. In the present invention, if '11' is recorded in the type field 52, the data frame is fragmented and transmitted. When the Type field 52 is '11', the final fragment number is recorded in the Subtype field 53. When the conventional Type field is '11', since the Subtype field is reserved from '0000' to '521', the subtype field is used to achieve compatibility with the conventional standard. However, this is only one embodiment and it is obvious to those skilled in the art that any number of different methods may be used to convey the final fragment number.

In addition to the Type field 52 and the Subtype field 53, the Frame Control field 51 has a Protocol Version field, a To DS field, a From DS field, a Retry field, a Pwr Mgt field, a More Data field, a WEP field, and the like. It may further include the Other field.

The Sequence Control field 54 is a Fragment number field 55 in which the fragment number of the current data frame (or current fragment) is recorded, and the identification number of the MSDU to which the current frame belongs (the sequence number corresponds to the IEEE 802.11 series standard). Is divided into a Sequence Number field 56 to be recorded. For example, when three pieces of fragmented data are transmitted, [sequence number: fragment number] may be represented as [1: 0], [1: 1], [1: 2], respectively.

5 is a diagram illustrating a configuration of a block ACK frame 100 according to an embodiment of the present invention. In the present invention, since the block ACK request frame 10 can use the same form as it is, it will not be defined separately.

The block ACK frame 100 may be composed of a MAC header region 190 and a payload region 150, 160, 170. And, it may further include the FCS field 180 as described in FIG. The MAC header region may include a Frame Control field 110, a Duration field 120, an RA field 130, and a TA field 140, and the payload region may include a BA Control field 150, a Block, It may include an Ack Starting Sequence Control field 160 and a Block Ack Bitmap field 170.

The frame control field 110 has the same format as shown in FIG. In the case of the block ACK frame 100, a value indicating a control frame is recorded in the type field 52, and a subtype value of the ACK frame 100 is recorded in the subtype field 53. The subtype value may be used by designating one of the reserved values.

In the Duration field 120, a value equal to or greater than the sum of the transmission time and the SIFS interval of the block ACK frame 100 is recorded. In addition, the address of the station for requesting the block ACK and receiving the block ACK is recorded in the RA field 130, and the address of the station transmitting the block ACK is recorded in the TA field 140.

The BA Control field 150 is a bit value for distinguishing between 'normal mode', 'compression mode' and '1 bit mode' among the bit pair bitmap methods (hereinafter, referred to as "mode bit"). A Mode Selection field 152 in which " " is recorded and a TID field 153 in which a traffic identifier (hereinafter referred to as a TID) is recorded. Here, the normal mode and the compression mode are represented using bit pairs, whereas the 1-bit mode uses one bit to confirm transmission for one fragment. Embodiments of each mode will be described later.

Further, the method may further include a Bitmap Length field 151 in which the number m of bit pairs included in the Block Ack Bitmap field 170 is recorded.

The Block Ack Starting Sequence Control field 160 transmits the Starting Sequence Number field 162 in which the identification number of the MSDU to which the frame to start transmission is started, that is, the start sequence number, is recorded by the set of bit pairs. It is composed of a Fragment Number field 161 in which the fragment number of the frame to be checked is recorded.

In the Block Ack Bitmap field 170, a bitmap composed of at least one bit pair 171 or the like (hereinafter, referred to as a set of bit pairs) is recorded. This bit pair is a format proposed in the present invention to record the transmission confirmation result more efficiently by improving the conventional recording method of the Block Ack Bitmap field. In general, since the sum of the size of the bit pair may not be in the Octet unit, the padding field 174 may be added after the bit pair. In the padding field 174, a dummy bit (eg, 0) having a minimum number of bits that adds up the bit pair and the size recorded in the Block Ack Bitmap field 170 to the unit of Octet is recorded. If the total size of the bit pairs is 26 bits, if the size of the padding field 174 is set to 6 bits, 32 bits, or 4 bytes, can be fit as a whole. However, the padding field 140 may be omitted because it is not an essential item for defining a protocol according to the present invention.

The bit pairs 171, 172, 173, etc., consist of ACK bits 171a and MSDU bits 171b. In the ACK bit 171a, a bit for confirming whether the corresponding frame is normally transmitted is recorded. If the frame is normally received, the bit may be recorded as 1, otherwise it may be recorded as 0.

In the MSDU bit 171b, a bit indicating the "range" of the data frame indicated by the first bit is recorded. According to an embodiment of the present invention, the range indicates, in the MSDU bit 171b, that the ACK bit indicates transmission confirmation for one fragment (or one MSDU if one MSDU is not fragmented) (electronic). It may be understood as a meaning of distinguishing whether the latter indicates transmission confirmation for all fragments after the current fragment belonging to one MSDU. The MSDU bit 171b may be written as 0 in the former case and 1 in the latter case.

6 to 11 are diagrams for describing how the block ACK frame 100 is configured according to various embodiments. In the present invention, there are two methods of constructing a bitmap using bit pairs: a general mode and a compressed mode. Hereinafter, [A: B] is an indication for identifying a frame, where A is an identification number assigned to an MSDU to which a fragment transmitted by an originator belongs, that is, a sequence number, B is a sequence number of a fragment, In other words, it means a fragment number (starting from 0).

6 shows the structure of the block ACK frame 100 when all of [1: 0], [2: 0], [3: 0], and [4: 0] are normally received. It does not happen. In this case, the normal mode and the compression mode are the same. In this case, the starting sequence number (Starting Sequence Number = 1) and the fragment number (Fragment number = 0) of the frame [1: 0] are recorded in the Block Ack Starting Sequence Control field 160. In the Block Ack Bitmap field 170, bit pairs consisting of ACK bits and MSDU bits for the target frame are sequentially recorded. However, in this case, since only the bit pairs are in the unit of bytes, a separate padding field is not necessary.

Since [1: 0], [2: 0], [3: 0], and [4: 0] are 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 MSDU may be displayed as 1 because the MSDU is completed in the corresponding frame, and 0 because it is an indication of whether an ACK is indicated for one frame. However, it would be more desirable to fill in 1 in terms of clarifying the meaning of completion in one MSDU. X is interpreted in the same sense as in the present embodiment.

7 shows the structure of the block ACK frame 100 when the [1: 0], [2: 0], [2: 1], [3: 0], and [4: 0] are normally received. It is represented as. Here, the second MSDU (sequence number = 2) is fragmented. As in FIG. 6, a start sequence number (= 1) and a fragment number (= 0) of [1: 0] are recorded in the Block Ack Starting Sequence Control field 160. In the Block Ack Bitmap field 170, bit pairs consisting of ACK bits 171a and MSDU bits 172b for the target frame are sequentially recorded.

Since [1: 0], [2: 0], [2: 1], [3: 0], and [4: 0] were all received normally, the first bit (ACK bit) of the bit pair is filled with 1 Since [1: 0], [3: 0], and [4: 0] are completed frames, the second bit (MSDU bit) is filled with X. However, since [2: 0] exists after [2: 0] having such a sequence number and another fragment number, the second bit of the pair of bits for [2: 0] is represented by 1 and [2: 0]. All subsequent marks indicate that the fragment has been successfully received.

As described above, it is preferable to display the fragmented MSDU at once, but in the same situation, when the MSDU is fragmented as shown in FIG. 8, a method of displaying the fragment by MSF may be considered. A method of simultaneously displaying one MSDU as shown in FIG. 7 is defined as a "compression mode", and a method of displaying each fragment as shown in FIG. 8 as a normal mode is defined as "normal mode".

9 shows that the sender has transmitted [1: 0], [2: 0], [2: 1], [2: 2], [3: 0], but the receiver has [1: 0], [2: 0] ], The structure of the block ACK frame 100 is shown when only [3: 0] is normally received. Here, it can be seen that the second MSDU is divided into three fragments. In the Block Ack Starting Sequence Control field 160, the start sequence number (= 1) and the fragment number (= 0) of the frame [1: 0] are recorded.

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 to confirm transmission for 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]. In this way, it can be seen that the recipient received only a portion of the plurality of fragments but did not receive the rest of the fragments in the Last Frame Number field 53 of the data frame 50 to be confirmed for transmission. This is because the number of fragments is recorded.

6 to 9, the embodiment of FIG. 6 is an example of a compression mode and a normal mode, and the embodiment of FIG. 8 is an example of a general mode, and the embodiments of FIGS. 7 and 9 are illustrated in FIG. An example is an example expressed in compression mode. When both of the embodiments can be expressed, the compression mode is more efficient than the normal mode. However, not all cases may be expressed in the normal mode and the compressed mode, and may be expressed in the normal mode or the compressed mode only.

When a part of the middle part of the consecutive fragments is missing as shown in the embodiment of FIG. 10, the expression may be expressed only in the normal mode, and may not be expressed in the compressed mode. If the sender sent [1: 0], [2: 0], [2: 1], [2: 2], [3: 0], but the receiver did not receive only [2: 1] of these, If the block ACK frame 100 is represented in the normal mode, it is as shown in FIG.

In the embodiment of Fig. 11, the sender has transmitted [1: 0], [2: 0], [2: 1], [2: 2], [3: 0], but the receiver has [1: 0], [ 3: 0], the block ACK frame 100 is expressed in the compression mode when only the normal reception is received. In this case, only the compression mode can be used. This is because the receiver has not received any frame having an MSDU of 2, and thus cannot know that the total number of fragments is three.

In this case, 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 completed 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 normally received. As such, none of the frames for the second MSDU have been received, but by filling the first bit with 0 and the second bit with 1 at the position of [2: 0], [2: 0] and all subsequent fragments are It may indicate that it was not received.

As described above, in some embodiments, only one mode of the normal mode and the compression mode may be expressed, and in some cases, both may be represented. If both can be represented, it would be desirable to use a more efficient compression mode.

On the other hand, when it is possible to express in the normal mode, it is possible to confirm transmission in a more improved manner. Both the general mode and the compression mode described above are embodiments expressed using bit pairs. However, in the normal mode, since transmission is confirmed for each fragment, the MSDU bits 171b may be expressed as all zeros. Therefore, when it is possible to express in the normal mode, transmission confirmation can be performed using only one ACK bit 171a. The mode represented by 1 bit is defined as "1 bit mode".

12 shows the configuration of the Block Ack Bitmap field 170 when using the 1-bit mode. In this case, the field 170 is composed of only one bit of ACK bits 175, 176, 177, etc., instead of a pair of bits, and the padding field 174 may also be used to fit the Octet. As shown in FIG. 10, the case represented by the normal mode is represented by FIG. This result is the same as omitting the MSDU bit 171b from the bit pair in normal mode.

The conventional Block Ack Bitmap field (23 of FIG. 2) is also the same in that it consists of a set of bits for transmission confirmation. However, in the present invention, the 1-bit mode uses a variable size Block Ack Bitmap field 170 unlike the conventional art. In addition, the conventional Block Ack Bitmap field (23 in FIG. 2) uniformly allocates 16 bits even in transmission confirmation for one non-fragmented frame or 16 or less fragmented frames (fragments). By allocating one bit to each frame or fragment, there is a certain bit saving effect. Accordingly, when the ACK bits (175, etc.) are recorded in the Block Ack Bitmap field 170 in accordance with the 1-bit mode, the ACK bits are continuously recorded. In the present invention, the sender informs the receiver of the fragment number (final fragment number) through the data frame, so that the fragment information can be clearly known between the sender and the receiver.

Meanwhile, which mode is used to configure the bitmap may be recorded in the Mode Selection field 152 of FIG. 5. For example, '00' may indicate a normal mode, '01' indicates a compression mode, and '10' indicates a 1-bit mode.

The number (m) of bit pairs (in the compression mode and the normal mode) or bits (ACK bit (in the 1-bit mode) included in the Block Ack Bitmap field 170 is recorded in the Bitmap Length field 151. Can be. For example, in the case of FIG. 7, 4 will be recorded in the Bitmap Length field 151, and 5 will be recorded in the Bitmap Length field 151 in the case of FIG. 8. However, when the bit pair (171 or the like) or the ACK bit (175 or the like) is recorded in the receiver according to the rule of each mode, the size may be uniquely determined. Therefore, the transmission confirmation of the plurality of data frames can be sufficiently performed only by sequentially recording bit pairs or ACK bits and transmitting them to the sender. Thus, it is noted that the Bitmap Length field 151 is not necessary to practice the present invention, and may replace the portion of the Bitmap Length field 151 with a reserved field.

14 is a block diagram illustrating a configuration of a wireless station 200 according to an embodiment of the present invention, which transmits the same block ACK frame 100. The wireless station 200 may include a block ACK generation module 210, a MAC header reading module 220, a transmission / reception module 230, a control module 240, and a memory 250. .

The MAC header reading module 220 reads the sequence number of the MSDU to which the frame belongs, the fragment number of the frame, and the fragment number of the MSDU to which the frame belongs, from the MAC header of the received data frame. The sequence number of the MSDU can be known from the Sequence number field 56 of the MAC header, and the fragment number can be known from the Fragment number field 55 of the MAC header. The fragment number (or last fragment number) of the MSDU can be known from the Subtype field 53 of the MAC header. This is because, when the MSDU is fragmented and transmitted, the Type field 52 of the data frame including each fragment is filled with '11', and the last fragment number is recorded in the Subtype field 53. to be.

As such, the information read from the MAC header is stored in the memory 250.

The block ACK generation module 210 generates a payload of the block ACK frame 100 according to the present invention by using the information read from the MAC header stored in the memory 250. The payload may include a BA Control field 150, a Block Ack Starting Sequence Control field 160, and a Block Ack Bitmap field 170.

The BA Control field 150 includes a Mode Selection field 152 in which bit values for distinguishing a general mode, a compression mode, and a 1-bit mode are recorded, and a TID field 153 in which a traffic identifier is recorded. It may further include a Bitmap Length field 151 in which the number of bit pairs (m) included in the Block Ack Bitmap field 170, or in the case of 1-bit mode, the number of ACK bits (k) is recorded. have.

The Block Ack Starting Sequence Control field 160 starts the transmission check and the Starting Sequence Number field 162 in which the identification number of the MSDU to which the frame to which transmission is to be started is to be started, ie, the sequence number, is recorded by the bitmap. It consists of a Fragment Number field 161 in which the fragment number of the frame to be recorded is recorded.

The Block Ack Bitmap field 170 is composed of at least one or more bit pairs (171, etc.) or at least one or more ACK bits (175, etc.). The padding field 174 may further include a padding field 174 for fitting the entire Block Ack Bitmap field 170 in octets after the bit pair or the ACK bit.

In the normal mode and the compressed mode, the bit pair 171 constituting the bitmap field 170 includes an ACK bit 171a and an MSDU bit 171b. In the ACK bit 171a, a bit for confirming whether the corresponding frame is normally transmitted is recorded. The MSDU bit 171b includes bit information for distinguishing whether the ACK bit indicates transmission confirmation for one fragment (or MSDU) or transmission confirmation for all fragments after the current fragment belonging to one MSDU. Is recorded.

On the other hand, in the 1-bit mode, a bit for confirming whether the corresponding frame is normally transmitted is recorded in the ACK bit 175 constituting the Bitmap field 170.

In addition, the block ACK generation module 210 includes a BA Control field 150, a Block Ack Starting Sequence Control field 160, and a Block Ack Bitmap field 170, and payload of the block ACK frame 100. After generating, by generating and adding the necessary MAC header 190 for the payload transmission, the block ACK frame 100 is generated.

The control module 240 controls the operation of other modules in the wireless station 100, and may be implemented as a central processing unit (CPU), a microcomputer, or the like.

The transmit / receive module 230 receives the data frame and the block ACK request frame 10 from another wireless station, that is, the sender, and transmits the block ACK frame 100 generated by the block ACK generating module 210 to the sender. . The transmission / reception module 230 demodulates the received radio signal to restore binary data, modulates the binary data to be transmitted into a radio signal, and transmits the spatial data.

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, firmware, micro 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 overall operation according to an embodiment of the present invention.

First, the wireless station 200 receives a data frame from another wireless station (S10). The MAC header of the data frame is read (S20). In the MAC header reading process, at least the sequence number of the MSDU to which the data frame belongs and the fragment number of the frame are read. If the data frame includes some fragments in the fragmented MSDU, the fragment number of the MSDU is read. Whether the data frame is fragmented can be known by checking whether the Type field 52 is '11', and the number of fragments at that time can be known by reading the Subtype field 53. The wireless station 200 stores the sequence number, the fragment number, and the last fragment number (if present) in the memory 250 (S30).

The process of S10 to S30 is repeated until the wireless station 200 receives the block ACK request frame 10 from the sender. If the wireless station 200 receives the block ACK request frame (YES in S40), then a process (S50 to S90) of generating and transmitting a block ACK frame is performed.

The wireless station 200 first records in the Block Ack Starting Sequence Control field 160 the sequence number of the MSDU to which the frame to start transmission check belongs and the fragment number of the frame to start the transmission check (S50).

If the bit pairs recorded in the bitmap are expressed in the compression mode, the bit pairs are recorded in the Block Ack Bitmap field 170 according to the compression mode (S60). Bit pairs are recorded in the Ack Bitmap field 170 (S65). If it is to be expressed in the 1-bit mode, ACK bits (175, etc.) are recorded in the Block Ack Bitmap field 170 according to the 1-bit mode (S69). As an example of selecting the mode as described above, when both the compression mode and the 1-bit mode can be expressed, the mode in which the size of the bitmap configured for each mode is actually smaller can be selected. When it can be expressed in the normal mode, it can always be expressed in the 1-bit mode, it is preferable to use a more efficient 1-bit mode.

Next, the mode bit corresponding to each mode is recorded in the BA Control field 150 (S70).

The wireless station 200 adds a MAC header 190 to a payload consisting of the BA Control field 150, the Block Ack Starting Sequence Control field 160, and the Block Ack Bitmap field 170. An ACK frame 100 is generated (S80). Then, the generated block ACK frame 100 is transmitted to the other wireless station.

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. You will understand. 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 block 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.

Claims (18)

A method of transmitting an ACK frame for receiving at least one data frame from a transmitting station and acknowledging the response with one ACK frame, (a) receiving a frame from the transmitting station and storing at least an identification number of the received data frame and a fragment number and a final fragment number of the data frame if the data frame is a fragmented frame; (b) recording a set of bit pairs for each of the received data frames using the stored information, wherein the bit pairs include a first bit for confirming whether the corresponding frame is normally transmitted; Configured as a second bit indicating a range of data frames to indicate; (c) generating an ACK frame including the recorded set of bit pairs; And (d) transmitting the generated ACK frame to the transmitting station. The method of claim 1, And the set of bit pairs has a variable size. The method of claim 1, wherein the range of the data frame is A method of transmitting an ACK frame, which is one of a range representing one fragment or a range representing all fragments after the current fragment belonging to one MSDU. The method of claim 1, wherein step (c) And recording the identification number of the frame for which transmission confirmation is to be started and the fragment number of the frame for which transmission confirmation is to be started with the set of bit pairs. The method of claim 4, wherein step (c) If the set of bit pairs is not in units of octets, adding dummy bits to be in units of octets. The method of claim 1, wherein the identification number And a sequence number of a MAC Service Data Unit (MSDU) to which the received data frame belongs. The method of claim 1, wherein the last fragment number is recorded in a Subtype field of the received data frame. The method of claim 1, wherein the first bit is 1 when the frame is normally received, otherwise 0 is recorded. The method of claim 1, wherein the second bit 1 if the first bit indicates a transmission acknowledgment for a corresponding frame, and 0 otherwise. The method of claim 1, wherein step (b) ACK frame transmission method performed when an ACK frame transmission request is received from the transmitting station. A method of transmitting an ACK frame for receiving at least one data frame from a transmitting station and acknowledging the response with one ACK frame, (a) receiving a frame from the transmitting station and storing at least an identification number of the received data frame and a fragment number and a final fragment number of the data frame if the data frame is a fragmented frame; (b) successively writing bits that confirm whether each of the received data frames has been normally transmitted using the stored information; (c) generating an ACK frame comprising the recorded bits; And (d) transmitting the generated ACK frame to the transmitting station. The method of claim 11, And the set of bits has a variable size. The method of claim 11, wherein step (c) And recording the identification number of the frame for which transmission confirmation is to be started and the fragment number of the frame for which transmission confirmation is to be started with the set of bit pairs. The method of claim 11, wherein the identification number And a sequence number of the received data frame. The method of claim 11, wherein the bit is 1 when the frame is normally received, otherwise 0 is recorded. The method of claim 11, wherein step (b) ACK frame transmission method performed when an ACK frame transmission request is received from the transmitting station. An ACK frame transmitting apparatus for receiving at least one frame from a transmitting station and acknowledgment with one ACK frame thereto. Means for receiving a frame from the transmitting station and storing at least an identification number of the received data frame and a fragment number and a final fragment number of the data frame if the data frame is a fragmented frame; Means for recording a set of bit pairs for each of the received data frames using the stored information, wherein the bit pairs include: a first bit for confirming whether the corresponding frame is normally transmitted; and a data frame represented by the first bit. Said means configured as a second bit representing a range of; Means for generating an ACK frame containing the recorded set of bit pairs; And Means for transmitting the generated ACK frame to the transmitting station. An ACK frame transmitting apparatus for receiving at least one data frame from a transmitting station and acknowledging a single ACK frame thereto. Means for receiving a frame from the transmitting station and storing at least an identification number of the received data frame and a fragment number and a final fragment number of the data frame if the data frame is a fragmented frame; Means for successively recording bits for verifying whether each of the received data frames has been normally transmitted using the stored information; Means for generating an ACK frame comprising the recorded bits; And Means for transmitting the generated ACK frame to the transmitting station.

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