CN1735002B - Method for reporting reception result of packet in mobile communication system - Google Patents

Abstract

A bitmap structure is disclosed that enables the size of a bitmap field containing reception result information to be greatly reduced while adequately performing its acknowledgment function. To this end, a message area of a recording indicator enabling confirmation of success or failure of reception of the largest admissible SN-level packet that can be handled by a block ACK is allocated. A message area for recording only reception results of packets that have not been successfully received is also allocated. The receiver confirms the unsuccessfully received packets through the indicator, and resends these unsuccessfully received packets. In addition, the sender provides the number of SN-level packets and the maximum number of fragmented packets to the receiver. The receiving side determines the optimal bitmap configuration scheme, and transmits the reception result of each segmented packet to the sending side based on the determined bitmapping scheme.

Description

Method for reporting reception result of packet in mobile communication system

technical field

The present invention relates to a bit map structure for a reception result of an application retransmission technique report packet in a mobile communication system, and a method for transmitting/receiving the reception result.

Background technique

In general, radio channels can cause errors in transmitted packets under the influence of multipath fading, interference between users, noise, and the like. Solutions to this problem include: Forward Error Correction Code (FEC) schemes, in which the possibility of errors is reduced by additionally sending redundant information; Automatic Repeat Request (ARQ) schemes, in which when errors occur, Retransmission of packets where errors have occurred is requested; and a Hybrid Automatic Repeat Request (HARQ) scheme, which combines the above two schemes.

In the ARQ scheme, a receiver notifies a transmitter whether a received packet is erroneous using an acknowledgment (ACK)/non-acknowledgement (NACK) signal. The ACK signal confirms to the sender that the corresponding packet has been received by the receiver. Conversely, a NACK signal confirms to the sender that the receiver failed to receive the corresponding packet. If the sender receives a NACK signal, the sender sends the corresponding packet to the receiver.

In addition to the general ARQ scheme in which reception results are confirmed on a packet-by-packet basis, there is a block ARO scheme in which reception results of a plurality of transmission packets are confirmed as a whole by a block ARQ message.

FIG. 1 is a diagram showing a basic concept of general block ARQ based on an example assuming that a block ARQ scheme is applied to every three packets. Referring to FIG. 1, the transmitter sequentially transmits three packets, packet #1, packet #2, and packet #3. These three packets (Packet #1 to Packet #3) have the same destination address (DA), eg DA2. Each pack (packet #1 to pack #3) is provided with a sequence number (SN) and a fragment number (FN). SN indicates the order in which packets are sent from the upper layer. Even packets with the same SN can be sent in multiple packets when occasionally required. FN indicates the order in which a plurality of packets divided by transmission are transmitted from a packet having one same SN.

The receiver checks whether packets are continuously received and which packets are not received by comparing the SN and FN of received packets with those of previously received packets. In the following description, a packet on the SN level will be referred to as an 'SN level packet', and a packet divided from the SN level packet will be referred to as a 'fragmented packet'. When a package is not called an SN-level package or a segment package, but the package is simply called a "packet", it means that the above-mentioned two types of packages are merged.

Among the three packets, the first and second packets (packet #1, packet #2) are fragmented packets with the same SN (eg, SN1) and different FNs (eg, Frag1, Frag2). The third packet (package #3) is an SN-level packet having a different SN (for example, SN2) from the SNs of the first and second packets (package #1, packet #2).

In FIG. 1 , it is assumed that the receiver successfully receives the first and third packets (packet #1, packet #3) and fails to receive the second packet (packet #2).

The receiver configures a Block ACK message on the basis of the reception result as described above and transmits the configured Block ACK message to the transmitter. The Block ACK message includes a header and a payload. The destination address DA1 is recorded in the header. The destination address DA1 is the sender's address. The reception result of each received packet is recorded in the payload.

Applying the assumption mentioned above, ACK information is recorded as the reception result corresponding to the first and third packets (Packet #1, Packet #3), and NACK information is recorded as the reception result corresponding to the second packet (Packet #2) . The SN and FN of the corresponding packet are recorded together in the reception result.

The sender receives a block ACK message. The sender confirms that the receiver successfully received the first and third packets (Packet #1, Packet #3) and failed to receive the second packet (Packet #2) through the Block ACK message. Thereafter, although not shown in FIG. 1, the sender retransmits the second packet (packet #2).

The above-mentioned scheme in which the reception results of all received packets are recorded in one block ACK message can be implemented in various ways. However, in order to use messages with the shortest length, a bit-mapping scheme is employed.

Figures 2 to 4 show examples of using bitmap schemes for acknowledging received results. Referring to FIG. 2, the block ACK message includes a block ACK start sequence field and a bitmap field. The bitmap field consists of N ACK report fields. 'N' is a value corresponding to the maximum SN and represents the maximum number of sequences that can be confirmed. That is, 'N' may be defined as the maximum allowable number of SN-level packets that can be processed by one block ACK message.

The first SN level packet processed with the bitmap in the corresponding message is recorded in the Block ACK Start Sequence field. Each of the reception results of N consecutive packets starting from the packet having the SN recorded in the Block ACK start sequence field is recorded in the bitmap field.

Each ACK report field constituting the bitmap field is divided into (M×8) regions b0, b1, b2, ..., b(n ),..., b(8×M-1). Hereinafter, such areas b0, b1, b2, ..., b(n), ..., b(8×M-1) will be referred to as 'reception result information field'. This is because reception results are acknowledged on a packet-by-packet basis. Therefore, if the reception result is represented by one bit, M octets are used for the total reception result information field of one SN level packet, so the bitmap field has a total length of M×N octets.

For example, when SN=1 is recorded in the block ACK start sequence field, the reception result of the segmented packet with SN=1 and FN=n−1 will be recorded in the reception result information field b(n) 210 . If the receiver successfully receives this segmented packet, '1' is recorded in the reception result information field b(n) 210 . Otherwise, '0' is recorded in the reception result field b(n) 210 if the receiver fails to receive the segmented packet. This is based on the assumption that '1' is an indicator bit for successful reception and '0' is an indicator bit for failed reception. As another example, when '5' is recorded in the Block ACK Start Sequence field, if a fragmented packet has SN=6 and FN=3, then '1' is set to the third bit of the second octet .

FIG. 3 shows the above-mentioned general example when applied to a system based on the IEEE 802.16 standard (802.16), and FIG. 2 shows the same example when applied to a system based on the IEEE 802.11e standard (802.11e).

The block ACK message shown in Figure 3 includes a connection ID field, an ACK control field, and multiple ACK MAP fields. The ACK control field includes a field in which the start SN is recorded and a field in which the number of ACKMAP(m) is recorded. The number of ACKMAP fields is equal to the number of ACKMAP(m). The ACK MAP field has the same structure as that of the ACK report field in FIG. 2 . In FIG. 3, each of the connection ID field, the ACK control field, and the plurality of ACK MAP fields is configured as a field of 2 octets. Therefore, the Block ACK message has a total length of '(m+2)×2'. Usually, in 802.16, 'm' is a variable value and the maximum number of fragmented packets is 16.

The Block ACK message shown in Figure 4 includes a BA Start Sequence Control field and a BA Bitmap field. Information indicating the start sequence recorded in the bitmap field is recorded in the BA start sequence control field. The BA Bitmap field consists of multiple ACK MAP fields. Each ACK MAP field has the same structure as that of the ACK report field in FIG. 2 . For example, in 802.11e, ACK processing for a maximum of 64 SN-level packets can be performed simultaneously, and one SN-level packet can be divided into 16 fragmented packets. Therefore, when each ACK MAP field is configured as a 2-octet field, the BA bitmap field must remain 128 octets in size.

Contents of the invention

As mentioned above, if the reception result is confirmed using the conventional bitmap scheme, resource waste occurs. That is, in the conventional bitmap scheme, the bitmap is configured by considering that each SN level packet will be divided into maximum fragmented packets. Therefore, when a reception result corresponding to an SN-level packet is transmitted, the SN-level packet is not divided into fragment packets or is not divided into the maximum number of fragment packets, resulting in a reception result that is not used in the bitmap field information field. Such a reception result information field may be called an unnecessary resource.

Therefore, the present invention has been made to solve at least the above-mentioned problems present in the prior art, and it is an object of the present invention to provide a method for minimizing the length of messages to be sent.

A further object of the present invention is to provide a method for assigning an indicator bit area to a reception result send message which enables packets that have not been successfully received to be quickly confirmed.

Another object of the present invention is to provide a method for transmitting reception result information of only packets that have not been successfully received.

Another object of the present invention is to provide a method for confirming unsuccessfully arrived packets through indicator bits corresponding to respective packets and transmitting reception result information of unsuccessfully received packets.

Another object of the present invention is to provide a method for determining the size of a bitmap field in which the reception result information is recorded in a message transmitting reception result information based on the number of packets not successfully received.

Another object of the present invention is to provide a method for expanding a message area for sending reception result information when the number of packets not successfully received exceeds a threshold.

A further object of the present invention is to provide a method for optimizing the size of a bitmap by pre-negotiation.

Another object of the present invention is to provide a frame structure for optimizing the size of the bitmap through pre-negotiation.

A further object of the present invention is to provide a method for transmitting the number of SN-level packets and the number of fragmented packets from the sender to the receiver to optimize the size of the bitmap.

A further object of the present invention is to provide a method for optimizing the size of the bitmap by the number of SN-level packets and the number of fragmented packets.

Another object of the present invention is to provide a frame structure for optimizing the size of the bitmap by the number of SN-level packets and the number of segment packets.

In order to achieve these objects, according to a first aspect of the present invention, there is provided a method for configuring a reception result report message for reporting a reception result of a received packet to the receiver in a receiver of a mobile system, wherein multiple A packet to be sent continuously is sent as a plurality of fragmented packets, the method comprising: recording an indicator each indicating reception success or failure of each of the received packets in the first bitmap of the reception result report message field; and creating in the reception result report message a second bitmap field in which reception results corresponding to packets not successfully received among the received packets are to be recorded, and each indicating a packet not successfully received The indicator bit of the reception success or failure of each of the fragmented packets is recorded in the second bitmap field.

In order to achieve the above-mentioned object, according to a second aspect of the present invention, there is provided a method for retransmitting a packet in response to a reception result report message from a receiver in a transmitter of a mobile communication system, wherein a plurality of will be Continuously sent packets are sent as a plurality of segmented packets, the method comprising: checking whether a packet that has not been successfully received exists by being recorded in an indicator of each packet in the first bitmap field of the reception result report message; an indicator bit present in the second bitmap field of the reception result report message to identify fragmented packets that were not successfully received corresponding to the packets that were not successfully received; and retransmitting the fragmented packets that were not successfully received and including Fragmented packets that were not successfully received.

In order to achieve the above-mentioned objects, according to a third aspect of the present invention, there is provided a method for configuring a bitmap in a mobile communication system, the method comprising: receiving information about the number of continuously received packets and the maximum number of fragmented packets information on the number; and determining the bitmap configuration scheme based on the information on the number of consecutively received packets and the maximum number of fragmented packets.

In order to achieve the above-mentioned purpose, according to a fourth aspect of the present invention, there is provided a method for receiving results of packets requested to be sent in a mobile communication system, the method comprising: when each packet is divided into one or more Continuously transmitting a plurality of packets (m) when fragmenting packets; and transmitting information on the number (m) of consecutively transmitted packets and the number (n) of fragmented packets.

In order to achieve the above-mentioned object, according to a fifth aspect of the present invention, there is provided a method for reporting the reception result of a received packet in a mobile communication system, the method comprising: continuous reception is divided into one or more m packets of fragmented packets; receive information about the number of consecutively received packets (m) and the number of fragmented packets (n); pass information about the number of consecutively received packets (m) and the number of fragmented packets (n) determine the bitmap configuration scheme according to the information of the bitmap; configure the bitmap including the reception result of each segmented packet according to the determined bitmap configuration scheme; and send the bitmap.

Description of drawings

The above-mentioned and other objects, features and advantages of the present invention will become more clear through the following detailed description in conjunction with the accompanying drawings, wherein:

FIG. 1 is a diagram illustrating a basic concept of a general block ARQ scheme;

2 to 4 are diagrams showing examples of acknowledging reception results using various conventional bit mapping schemes;

Fig. 5 is a diagram showing a hierarchical bitmap structure proposed according to the present invention;

6 and 7 are diagrams showing examples of confirmation reception results when the present invention is applied to 802.11n;

8 is a control flow diagram for explaining the operation of the sender according to the preferred embodiment of the present invention;

FIG. 9 is a control flow diagram for explaining the operation of the receiver according to the preferred embodiment of the present invention;

FIG. 10 is a diagram showing the structure of a block ACK request frame according to a preferred embodiment of the present invention;

FIG. 11 is a diagram showing the structure of a block ACK frame according to a preferred embodiment of the present invention; and

12A to 12C, 13A to 13C, and 14A to 14C are diagrams showing examples of operations according to a preferred embodiment of the present invention.

Detailed ways

Hereinafter, preferred embodiments of the present invention are described with reference to the accompanying drawings. It should be noted that similar components are denoted by like numerals even though they are shown in different drawings. Also, in the following description, a detailed description of known functions and structures incorporated herein will be omitted when it may obscure the subject matter of the present invention.

The present invention proposes a message having a structure that enables the size of a field (bitmap field) containing information according to a reception result to be optimized when an inherent function of confirming a reception result is sufficiently performed. In addition, the present invention proposes a message with a structure that greatly reduces the size of the bitmap. In the following description, a bitmap configuration method in which the size of the bitmap is reduced by reporting only the reception results of packets that have not been successfully received will be recommended as a first preferred embodiment. Also, a bitmap configuration method in which the size of the bitmap is optimized by reporting a reception result based on information provided by the sender will be recommended as a second preferred embodiment.

Hereinafter, a first preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The first embodiment of the present invention can be realized based on two factors.

First, the packet error rate (PER) in a general wireless data communication system is specified on a lower level. Second, packet loss is concentrated at a specific moment rather than uniformly distributed.

Considering these two factors, the number of error packets, if any, may be very small, and errors may be concentrated at a specific moment. Therefore, even if reception failure occurs, it can be expected that most packets are successfully received and only some packets fail to be received.

If the ARQ scheme is implemented in such a way that only the reception results of packets that are not successfully received are confirmed, the amount of information according to the confirmation of the reception results can be greatly reduced. Reduction of the amount of information according to acknowledgment of the reception result means a reduction in the size of the bitmap.

In the following detailed description, a block ACK message for reporting only a reception result corresponding to a fragmented packet of fragmented packets transmitted from an SN level packet that has not been successfully received is proposed. To this end, the field used to send an indicator enabling confirmation of success or failure to receive each of the maximum allowable SN-level packets that can be processed by a block ACK (hereinafter referred to as the 'SN-level bitmap field') is redesigned definition. In addition, a field for transmitting a specific reception result corresponding to an SN level packet that was not successfully received (hereinafter referred to as an 'ACK report field') is redefined. Here, the specific report result is an indicator enabling confirmation of the success or failure of receiving each of the segmented packets transmitted from one SN-level packet.

To configure such a block ACK message, the sender (the party that has received the packet) checks on an SN-by-SN basis whether there are packets that were not successfully received. Subsequently, for a packet that was not successfully received, the sender sets 'reception failure' to an indicator corresponding to the SN of the packet that was not successfully received in the SN-level bitmap field. In contrast, for a successfully received packet, the sender sets 'received successfully' to an indicator corresponding to the SN of the successfully received packet in the SN level bitmap field.

However, when multiple fragmented packets with the same SN are received, the receipt of these fragmented packets cannot be confirmed only through the SN-level bitmap field. In this case, separate information is required to enable verification of packets that were not successfully received.

Therefore, in the first embodiment of the present invention, the ACK report field is created individually according to the SN of the packet that was not successfully received. An indicator corresponding to each fragmented packet is recorded, ie, the indicator is recorded in the ACK report field on a FN-by-FN basis. These indicators indicate the success or failure of reception of segmented packets with the same SN. The ACK report field is configured by considering the maximum number of fragmented packets from one SN level packet.

The sender sends a Block ACK message thus configured to the receiver.

The receiver (the party that has sent the packet) confirms the success or failure of reception of each SN-level packet by checking the indicator recorded in the SN-level bitmap field of the Block ACK message. When there is an SN level packet that was not successfully received, the receiver checks an ACK report field corresponding to the SN level packet that was not successfully received. The receiver is notified of fragmented packets that were not successfully received by an indicator recorded in the ACK report field.

Fig. 5 shows the proposed hierarchical bitmap structure according to the present invention.

Referring to FIG. 5, a block ACK message having a hierarchical bitmap structure includes a block ACK start sequence field and a bitmap field. The bitmap field consists of the SN level bitmap field and the error SN packet bitmap field. The error SN packet bitmap field includes multiple ACK report fields (M×m ACK fields). Here, 'm' corresponds to the number of zeros ('0') set to the SN level bitmap field. 'M' is the number of SN class packets that were not successfully received. The SN of the first SN level packet processed by the bitmap in the corresponding message is recorded in the block ACK start sequence field. At this time, the first SN level packet may be defined as the first SN level packet to be acknowledged through the block ACK message. Here, it should be noted that the first SN-level packet cannot be interpreted as the first SN-level packet that was not successfully received.

An indicator indicating a reception result (reception success or failure) according to each SN (hereinafter referred to as 'SN quick reference bit') is recorded in the SN level bitmap field. The length of the SN-level bitmap field is determined by the maximum allowable number of SN-level packets that can be processed by a block ACK. That is, if the maximum allowable number of SN-level packets that can be processed by a block ACK is 8×N, the SN-level bitmap field has a length of N octets (8×N bits). Therefore, each bit that makes up the SN-level bitmap field is used as an SN quick reference bit for SN-by-SN allocation.

The error SN packet bitmap field includes an ACK report field. Since the ACK report fields are created individually according to the SNs of packets that were not successfully received, the number of ACK report fields must be equal to the number of SN-level packets that were not successfully received. Therefore, the Error SN Packet Bitmap field has a length of Mxm octets. Here, M octets, that is, the total length of the ACK report field is a fixed value, so the total length of the error SN packet bitmap field (M×m8) is determined by the number (m) of SN class packets that have not been successfully received bit bytes).

For example, the larger the number (m) of SN class packets that were not successfully received, the longer the total length (M x m octets) of the error SN packet bitmap field. Conversely, the smaller the number (m) of SN class packets that were not successfully received, the shorter the total length (M x m octets) of the error SN packet bitmap field. If there are no SN-level packets that were not successfully received, the Error SN-level packet bitmap field may not be present.

The mapping relationship between the ACK report field and the SN quick reference bit set to '0' can be established in various ways. In the simplest example, the ACK report fields are sequentially mapped corresponding to the SN order of the SN quick reference bits.

For example, if it is assumed that the value of the Block ACK Start Sequence field is 5 and the value of the SN Level Bitmap field is 11101011, then two ACK report fields exist in the Error SN Packet Bitmap field. The first of the two ACK report fields becomes the bitmap for SN level packets with SN=8 and the second becomes the bitmap for SN level packets with SN=10. Also, a scheme in which an indicator is allocated to an ACK report field may be employed.

An indicator for reporting the reception result of each segmented packet is recorded in the ACK report field. Therefore, there is an indicator corresponding to the maximum number of segment packets from which one SN level packet (M×8) can be divided. This is because the reception result is confirmed on a packet-by-fragment basis. In FIG. 5 , indicators are designated by 'b0, b1, b2, ..., b(n), ..., b(8×M-1)'. For example, if the indicator is represented by one bit, one ACK report field has a length of M octets.

Hereinafter, an example of actually configuring a block ACK message having the structure shown in FIG. 5 will be described.

The (n+1)th SN quick reference bit b(n) in the SN level bitmap field is set to '1' when all packets split from the SN level packet with SN=n+1 are successfully received . However, even when a fragmented packet is not successfully received, the (n+1)th SN quick reference bit b(n) in the SN level bitmap field is set to '0'. That is, even when a fragmented packet is not successfully received, the quick reference bit corresponding to the SN of the fragmented packet that was not successfully received is set to "failed to receive". In this case, separate information must be provided to enable verification of fragmented packets that were not successfully received.

If it is assumed that a fragmented packet with SN=n+1 and FN=n+1 is not successfully received, the (n+1)th SN quick reference bit, i.e. b(n) in the SN level bitmap field is set to '0', the ACK report field to be mapped to b(n) (hereinafter referred to as the mth ACK report field) is assigned to the SN packet bitmap field. Subsequently, a bit indicating failure of reception is set to the (n+1)th indicator b(n) in the mth ACK report field. At this time, the bit indicating successful reception is set to the remaining indicators except the (n+1)th indicator b(n) in the mth ACK report field. As an example, '0' is used as an indicator indicating reception failure, and '1' is used as an indicator indicating reception success.

6 and 7 show examples of messages for reporting reception results when the present invention as described above is applied to a system based on the IEEE 802.11n standard (802.11n). The examples shown in FIGS. 6 and 7 are distinguished from each other by the number of packets that were not successfully received. That is, if the number of MAC service data units (MSDUs) that are not successfully received does not reach a threshold (eg, 12), the message structure shown in FIG. 6 is used. However, if the number of MSDUs not successfully received is equal to or greater than a threshold (eg, 12), the message structure shown in Figure 7 is used.

Referring to FIG. 6, the block ACK message includes a BA control field, a BA start sequence control field, and a bitmap field of a BA error MSDU.

The BA Control field has a length of 2 octets. The BA Control field includes the Bitmap field and the TID field of the BAMSDU. The bitmap field of the BA MSDU consists of quick reference bits used to indicate the success or failure of reception of each SN level packet. The bitmap field of the BA MSDU is an area that has not been used in existing 802.11 and is reused in the present invention. Since FIG. 6 assumes that the number of MSDUs not successfully received is lower than 12, the bitmap field of the BA MSDU is configured with a size of 12 bits.

Additionally, any bit in the BA Control field can be assigned to a message indicator. As an example, the first bit in the BA control field may be assigned to a message indicator. The message indicator indicates the message type. In FIG. 6, '1' is used as a message indicator.

The SN of the first SN level packet processed by the bitmap in the corresponding message is recorded in the BA start sequence control field. The first SN level packet is the first transmitted packet among consecutively transmitted packets for block ACK, and it should be noted that the first SN level packet is not the first SN level packet that was not successfully received.

The Bitmap field of the BA Error MSDU consists of a number of ACK MAP fields not exceeding eleven in number. The bitmap field of the BA error MSDU has the same structure and function as that of the error SN packet bitmap field described above with reference to FIG. 5 , so a detailed description of the bitmap field of the BA error MSDU will be omitted.

Referring to FIG. 7, the Block ACK message includes a BA Control field, a BA Start Sequence Control field, a Bitmap field of a BA MSDU, and a Bitmap field of a BA Error MSDU.

Any bit in the BA control field is assigned to the message indicator. As an example, the first bit of the BA control field may be assigned to a message indicator. In FIG. 7, '0' is used as a message indicator. In addition, another bit in the BA control field is assigned to a success indicator. The success indicator indicates that all packets (assuming 64 MSDUs in Figure 7) were successfully received (designated by 'A' in the figure). The success indicator is set to '1' when all SN level packets are successfully received. However, even when an SN class packet is not successfully received, the success indicator is set to '0'. If the success indicator is set to '1', the bitmap field of the BA MSDU and the bitmap field of the BA error packet are not required.

The bitmap field of the BA MSDU performs the same function as the BA MSDU bitmap field function existing in the BA control field as shown in FIG. 6, so a detailed description thereof will be omitted. The only difference between the bitmap fields of the two BA MSDUs is that the bitmap field of the BA MSDU in Figure 7 has a size of 64 bits (8 octets) to indicate the success or failure of reception of 64 packets.

The Bitmap field of the BA Error MSDU consists of the ACK MAP field corresponding to the number of packets that were not successfully received. The bitmap field of the BA error MSDU has the same structure and function as that of the bitmap field of the error SN packet described above with reference to FIG.

Hereinafter, a second preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The second embodiment of the present invention assumes a system for sending block ACK request frames together with consecutive data frames from the sender to the receiver. The block ACK request frame includes information necessary to transmit the reception result of each data frame. The block ACK request frame may be sent before or after the data frame is sent. Of course, block ACK request frames and data frames may be sent simultaneously.

The receiver receives data frames and block ACK request frames. The receiver determines the bitmap configuration scheme based on the information received through the block ACK request frame, and then configures the bitmap according to the determined bitmap configuration scheme so that the bitmap includes the reception result of the data frame. Acknowledge bitmap to sender by block ACK frame.

In the second embodiment of the present invention, information on "the number (m) of SN class packets to be continuously transmitted" and "the maximum number (n) of fragmented packets" is transmitted through the block ACK request frame. Usually, SN-level packets that have been divided into a plurality of fragment packets are transmitted, if necessary. The maximum number of fragmented packets (n) is the maximum number of fragmented packets that can be made from SN level packets to be transmitted.

In the following description, an operation for transmitting a block ACK request frame at the sender side and a structure of the block ACK request frame will be discussed in detail. In addition, an operation for reporting a reception result on a packet-by-segment basis through a block ACK frame on the receiving side and a structure of the block ACK frame will be discussed in detail.

Also, in the example of the present invention, an operation performed when the number (m) of packets to be continuously transmitted and the maximum number of segmented packets are randomly given will be discussed.

Hereinafter, the operations of the sender and the receiver will be described in detail according to a preferred embodiment of the present invention.

Fig. 8 shows a control flow explaining the operation of the sender according to the preferred embodiment of the present invention.

Referring to FIG. 8, in step 810, the number (m) of packets to be transmitted is determined. The determination of 'm' is affected by the number of SN class packets to be sent consecutively. Each SN-level packet can be divided into multiple segmented packets for transmission. In step 812, the maximum number of fragmented packets is determined, in other words, the fragmentation status of each SN-level packet is verified. That is, the number of fragment packets divided from each SN-level packet is detected, and the SN-level packet from which the largest fragment packet is divided is determined. The number of fragment packets divided from the found SN-level packets is determined as the maximum number (n) of fragment packets.

In step 814, a Block ACK Request (BAR) frame is configured such that 'm' and 'n' determined above are included in the BAR frame. At this time, the SN of the first SN class packet to be transmitted is recorded in the block ACK start sequence control field of the BAR frame. The sender sends the BAR frame to the receiver. Figure 10 will discuss the structure of the BAR frame.

Although not shown in FIG. 8, the m SN level packets may be transmitted before or after transmission of the corresponding BAR frame. Of course, SN-level packets and BAR frames can be sent at the same time. In addition, the receiver provides the sender with a reception result corresponding to each segment packet of the m SN class packets. Reception results on a packet-by-segment basis are provided through Block ACK (BA) frames. The sender retransmits the segmented packets based on the reception result of each segmented packet obtained through the BA frame.

Fig. 9 shows a control flow explaining the operation of the receiving side according to the preferred embodiment of the present invention.

Referring to FIG. 9, in step 910, a receiver receives a BAR frame. In step 912, the recipient confirms 'm' and 'n' from the BAR frame.

Once the recipient verifies 'm' and 'n', the bitmap configuration scheme is determined via steps 914-918. The bitmap configuration scheme is determined by the total bitmap size, the bitmap size corresponding to one SN level packet, and the number of bits to be stuffed.

At step 914, the total bitmap size is determined. The total bitmap size is determined by 'm' and 'n' previously confirmed in step 912. As an example, the total bitmap size can be determined by equation (1), as follows:

Total bitmap size = ceiling[m×n/8] octets  …(1)

Among them, ceiling[x] represents the smallest integer among the integers exceeding 'x'. The total bitmap size can also be expressed as the total bitmap size in bits by multiplying the total bitmap size in octets by '8'.

For example, if 'm' is 2 and 'n' is 7, the total bitmap size is represented by ceiling[1.75]. Since 'ceiling[1.75]' represents the smallest integer greater than '1.75', the result is '2'. Therefore, the total bitmap size is determined to be 2 octets.

At step 916, the bitmap size to be allocated to each SN level packet is determined. Preferably, the same bitmap size is allocated to all SN level packets. When the same bitmap size is allocated in this way, the bitmap size of only one SN level packet is determined, and the determined bitmap size can be applied to the remaining SN level packets. For example, the bitmap size is determined to be 'n' previously confirmed in step 912. This is because reception results must be acknowledged on a packet-by-fragment basis.

According to the above-mentioned description, the sum of the bitmap sizes to be allocated to the respective SN level packets does not exceed the total bitmap size. That is, when the bitmap size is allocated to each SN level packet, the sum of the bitmaps is equal to the total bitmap size or remaining bits occur. At step 918, the number of bits to be stuffed is determined. However, when the sum of the bitmap sizes allocated to individual SN level packets is equal to the total bitmap size, there are no remaining bits and no padding is required. The number of bits to be filled can be summarized by equation (2), as follows:

ceiling[m×n/8]-m×n (2)

The unit of equation (2) is bit. The bitmap configuration scheme is determined by the total bitmap size previously determined through steps 914 to 918, the bitmap size according to each SN level packet, and the number of bits to be stuffed. In addition, bit values according to the reception result on a packet-by-segment basis are inserted into corresponding bit positions. As for this bit position, '1 (success)' and '0 (failure)' are used as bit values according to the reception result with reference to the SN and FN that the segmented packet has.

The bitmap structure will be described with reference to FIG. 11 . Examples of inserting bit values according to the reception results of the respective segment packets into corresponding bit positions are shown in FIGS. 12 to 14 . These examples will also be described in detail later.

At step 922, the BA frame including the bitmap is configured and sent to the sender.

Hereinafter, the structure of the BAR frame transmitted from the sender according to the second embodiment of the present invention will be described in detail.

The structure of the BAR frame proposed in the second embodiment of the present invention is characterized in that it includes the number (m) of SN class packets to be continuously transmitted and the number of fragmented packets (n )Information.

Fig. 10 shows the structure of a BAR frame on which the above-mentioned features are reflected.

Referring to FIG. 10, a BAR frame includes a BAR control field and a BAR start sequence control field. Each of the size of the BAR Control field and the BAR Start Sequence Control field is 2 octets.

The BAR control field includes a 'number of MSDU' field and a 'maximum number of fragmented packets' field. The number (m) of SN class packets to be continuously transmitted is recorded in the 'Number of MSDUs' field. The number (n) of fragmented packets of the SN class packet that is divided at most is recorded in the 'maximum number of fragmented packets' field. The size of the 'number of MSDU' field is 6 bits, and the size of the 'maximum number of fragmented packets' field is 4 bits.

The SN of the first SN packet to be transmitted among consecutively transmitted SN level packets is recorded in the BA start sequence control field.

Hereinafter, the structure of the BA frame transmitted to the receiver according to the second embodiment of the present invention will be described in detail.

The structure of the BA frame proposed in the second embodiment of the present invention is characterized in that it has a bitmap structure optimized using 'm' and 'n' supplied from the sender.

Figure 11 shows the structure of a BA frame on which the above mentioned features are reflected.

Referring to FIG. 11, a BA frame includes a BA start sequence control field and a BA bitmap field.

The top SN-level packet among consecutively received SN-level packets is recorded in the BA start sequence control field.

The total size of the BA bitmap field is determined by equation (1). That is, the total size of the BA bitmap field may be determined by 'm' and 'n' received through the BAR frame. The BA bitmap field consists of m bitmaps. Each of the m bitmaps is configured with a size of n bits. The bits of each constituent bitmap represent the reception result of the corresponding segmented packet. Each of the bitmaps corresponds to one of the successively received SN-level packets, and the reception result of the corresponding SN-level packets is recorded in the bitmap. At this time, the bit position at which the reception result of the segmented packet is recorded in the bit map is assigned by the SN and FN of the segmented packet. The remaining bits not used as bitmap in the BA bitmap field are subjected to padding. The number of bits to be filled can be obtained by equation (2).

Hereinafter, the event-by-event operation according to the second embodiment of the present invention will be described.

12A to 12C are diagrams for explaining an operation example in a case where all SN-level packets continuously transmitted from the sender are successfully received.

Fig. 12A shows that three SN level packets (SN=10, 11, 12) are sent consecutively. Here, the SN level packet with SN=10 is divided into four packet packets 10-1, 10-2, 10-3, 10-4, and the SN level packet with SN=11 is divided into three fragment packets 11 -1, 11-2, 11-3, SN level packets with SN=12 are divided into five segment packets 12-1, 12-2, 12-3, 12-4, 12-5. Therefore, 'm' is determined to be '3', and 'n' is determined to be '5'. The reason 'n' is determined to be '5' is that the number of segment packets to be divided at most from one SN level packet is '5'.

FIG. 12B shows a BAR frame structure in which m='3' and n='5' are set in the BAR Control field. The SN of the SN-level packet transmitted first among the three consecutively transmitted SN-level packets is '10'. Therefore, '10' is recorded in the BA start sequence control field.

If the receiving side receives the BAR frame having the structure as shown in FIG. 12B, it confirms the information recorded in the BAR control field and the BA start sequence control field. Thus, the receiving side recognizes that three SN-level packets having SNs of 10, 11, and 12 are continuously transmitted and that the maximum number of divided segment packets is '5'.

Subsequently, the receiver determines the total bitmap size by equation (1). According to equation (1), the total bitmap size is determined to be 2 octets of the bitmap (16 bits). The indicator bits indicating the reception result corresponding to each SN class packet are determined as 5-bit indicator bits. This is because an SN-level packet with SN=12 is divided into five fragment packets, and at least 5 bits are required to indicate a reception result on a fragment-by-fragment packet basis.

The four fragmented packets making up the SN class packet with SN=10 have all been successfully received. Therefore, the indicator bit indicating the reception result of the SN class packet with SN=10 is set to '11110' (specified by ① in FIG. 12C ). The upper four bits set to '1' indicate that each fragment packet has been successfully received. Since there is no segment packet corresponding to the last bit, the last bit is designated as '0'.

The three fragmented packets making up the SN level packet with SN=11 have all been successfully received. Therefore, the indicator bit indicating the reception result of the SN class packet with SN=11 is set to '11100' (specified by ② in FIG. 12C ). The upper three bits set to '1' indicate that each fragment packet has been successfully received. Since there is no segmented packet corresponding to the lower 2 bits, the lower 2 bits are set to '0'.

The five fragmented packets making up the SN class packet with SN=12 have all been successfully received. Therefore, the indicator bit indicating the reception result of the SN class packet with SN=12 is set to '11111' (specified by ③ in FIG. 12C ). Five bits set to '1' indicate that each fragment packet has been successfully received.

Once the 5 indicator bits indicating the reception result of each SN level packet are allocated, the 1 remaining bit appears in the bitmap whose total size has been determined to be 2 octets (16 bits). This is determined by equation (2). The receiver performs padding on the remaining bits. That is, the remaining bits are set to '0'.

In summary, the reception result of these consecutively sent SN-level packets is determined to be '11110 11100 111110'. The determined reception result is recorded in the BA bitmap field of the BA frame. In addition, '10' is recorded in the BA start sequence control field of the BA frame.

FIGS. 13A to 13C and FIGS. 14A to 14C are diagrams for explaining an operation example in a case where some SN-level packets are not successfully received from among SN-level packets continuously transmitted from the sender.

FIG. 13A shows that three SN class packets (SN=10, 11, 12) are sent consecutively. Here, the SN-level packet with SN=10 is divided into four fragmented packets 10-1, 10-2, 10-3, 10-4, and the SN-level packet with SN=11 is divided into three fragmented packets 11-1, 11-2, 11-3, SN level packets with SN=12 are divided into five segmented packets 12-1, 12-2, 12-3, 12-4, 12-5. Therefore, 'm' is determined to be '3', and 'n' is determined to be '5'. The reason 'n' is determined to be '5' is that the number of segment packets divided from one SN class packet at most is '5'. Among the fragmented packets, fragmented packets corresponding to 11-2, 12-2, and 12-4 were not successfully received.

FIG. 13B shows a BAR frame structure in which m='3' and n='5' are set in the BAR Control field. The SN of the SN class packet to be transmitted first is '10'. Therefore, '10' is recorded in the BA start sequence control field.

If the receiving side receives the BAR frame having the structure as shown in FIG. 13B, it confirms the information recorded in the BAR control field and the BA start sequence control field. Thus, the receiving side recognizes that three SN class packets having SNs of 10, 11, and 12 are continuously transmitted and that the maximum number of divided packets into fragments is '5'.

Next, the receiver determines the total bitmap by equation (1). According to equation (1), the total bitmap size is determined to be 2 octets (16 bits). An indicator indicating a reception result corresponding to each SN class packet is determined as 5 indicator bits. This is because an SN-level packet with SN=12 is divided into five fragment packets, requiring at least 5 bits to indicate the reception result on a fragment-by-fragment packet basis.

The four segment packets 10-1, 10-2, 10-3, 10-4 constituting the SN level packet with SN=10 have all been successfully received. Therefore, the indicator indicating the reception result of the SN class packet with SN=10 is set to '11110' (indicated by ① of FIG. 13C ). The upper four bits set to '1' indicate that each fragment packet has been successfully received. The last bit is set to '0' because there is no fragmented packet corresponding to that bit.

Among the three segment packets 11-1, 11-2, 11-3 that make up the SN level packet with SN=11, the segment packets corresponding to 11-1 and 11-3 have been successfully received, but the segment packets corresponding to 11- 2 The corresponding fragmented packet was not successfully received. Therefore, the indicator bit indicating the reception result of the SN class packet with SN=11 is set to '10100' (indicated by ② of FIG. 13C ). A bit set to '1' indicates that the corresponding segment packet 11-1, 11-3 has been successfully received. In contrast, a bit set to '0' indicates that the corresponding fragment packet 11-2 was not successfully received. The next 2 bits are set to '0' because there is no fragmented packet corresponding to these bits.

Among the five segmented packets 12-1, 12-2, 12-3, 12-4, 12-5 that make up the SN level packet with SN=12, corresponding to 12-1, 12-3 and 12-5 The fragmented packets have been received by Chen Gong, but the fragmented packets corresponding to 12-2 and 12-4 have not been successfully received. Therefore, the indicator bit indicating the reception result of the SN class packet with SN=12 is set to '10101' (indicated by ③ of FIG. 13C ). A bit set to '1' indicates that the corresponding segment packet 12-1, 12-3, 12-5 has been successfully received. In contrast, a bit set to '0' indicates that the corresponding segmented packet 12-2, 12-4 was not successfully received.

Once the 5 indicator bits indicating the reception result of each SN level packet are allocated, the remaining 1 bit appears in the bitmap, the total size of the bitmap has been determined to be 2 octets (16 bits). This is determined by equation (2). The receiver performs padding on the remaining bits. That is, the remaining bits are set to '0'.

In summary, the reception result of three consecutively received SN-level packets is determined to be '11110 10100 101010'. The determined reception result is recorded in the BA bitmap field of the BA frame. In addition, '10' is recorded in the BA start sequence control field of the BA frame.

Fig. 14A shows that two SN class packets (SN=10, 11) are sent consecutively. Here, an SN-level packet with SN=10 is divided into seven segmented packets 10-1, 10-2, 10-3, 10-4, 10-5, 10-6, 10-7 with SN=11 The SN level packet is divided into five segmented packets 11-1, 11-2, 11-3, 11-4, 11-5. Therefore, 'm' is determined to be '2', and 'n' is determined to be '7'. The reason why 'n' is determined to be '7' is that the number of segment packets which are divided at most from one SN class packet is '7'. Among these fragment packets, fragment packets corresponding to 10-3, 10-6, and 11-2 were not successfully received.

FIG. 14B shows a BAR frame structure in which m='2' and n='7' are set in the BAR Control field. The SN of the SN class packet to be transmitted first is '10'. Therefore, '10' is recorded in the BA start sequence control field.

If the receiver receives a structure as shown in FIG. 14B, it confirms the information recorded in the BAR control field and the BA start sequence control field. Thus, the receiving side recognizes that two SN class packets having SNs 10 and 11 are continuously transmitted and that the number of fragmented packets which are divided at most is '7'.

Next, the receiver determines the total bitmap size by equation (1). According to equation (1), the total bitmap size is determined to be 2 octets (16 bits). The indicator bits indicating the reception result corresponding to each SN class packet are determined as 7-bit indicator bits. This is because the SN class packet with SN=10 is divided into seven fragment packets, and at least 7 bits are required to indicate the reception result on a fragment packet-by-fragment packet basis.

Among the seven segment packets 10-1, 10-2, 10-3, 10-4, 10-5, 10-6, 10-7 that make up the SN level packet with SN=10, and 10-1, 10 Fragment packets corresponding to -2, 10-4, 10-5 and 10-7 have been successfully received, but fragment packets corresponding to 10-3 and 10-6 have not been successfully received. Therefore, the indicator bit indicating the reception result of the SN class packet with SN=10 is set to '1101101' (indicated by ① of FIG. 14C ). A bit set to '1' indicates that the corresponding segment packet 10-1, 10-2, 10-4, 10-5, 10-7 has been successfully received. In contrast, a bit set to '0' indicates that the corresponding segmented packet 10-3, 10-6 was not successfully received.

Among the five segment packets 11-1, 11-2, 11-3, 11-4, 11-5 that make up the SN level packet with SN=11, with 11-1, 11-3, 11-4 and 11 The fragment packet corresponding to -5 has been successfully received, but the fragment packet corresponding to 11-2 has not been successfully received. Therefore the indicator indicating the reception result of the SN class packet with SN=11 is set to '1011100' (indicated by ② in FIG. 14C ). A bit set to '1' indicates that the corresponding segment packet 11-1, 11-3, 11-4, 11-5 has been successfully received. In contrast, a bit set to '0' indicates that the corresponding segment packet 11-2 was not successfully received. The next 2 bits are set to '0' because there is no fragmented packet corresponding to those bits.

Once the 7-bit indicator bits indicating the reception result of each SN level packet are allocated, 2 remaining bits appear in the bitmap, the total size of the bitmap has been determined to be 2 octets (16 bits). This is determined by equation (2). The receiver performs padding on the remaining bits. That is, the remaining bits are set to '0'.

In summary, the reception results of the three consecutively transmitted SN class packets are determined to be '1101101101110000'. The determined reception result is recorded in the BA bitmap field of the BA frame. In addition, '10' is recorded in the BA start sequence control field of the BA frame.

In the above-mentioned second embodiment of the present invention, it is assumed that the sender provides the number of SN-level packets to be continuously transmitted and the maximum number of segment packets to the receiver to negotiate the bitmap in advance. However, the present invention can be implemented in such a manner that the receiving side confirms the number of continuously transmitted SN level packets and the maximum number of fragmented packets by receiving the continuously transmitted SN level packets. In this way, there is no need to send a Block ACK Request (BAR) frame on the sender side.

As described above, the present invention enables efficient use of transmission resources by providing a hierarchical bitmap structure. In addition, considering the actual communication environment, it can be expected not only to improve the utilization rate of transmission resources, but also to have a great influence on the performance of the mobile communication system. Furthermore, by negotiating the bitmap size in advance via the block ACK request, the number of bits to report the reception result can be optimized. This results in efficient use of transmission resources and improved performance of the mobile communication system.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that modifications may be made thereto without departing from the spirit and scope of the invention as defined by the appended claims. Various changes in form and detail.

Claims (6)

1. A method for configuring block acknowledgment BA frames in a wireless communication system, the method comprising: Receive a block acknowledgment request BAR frame from the sender; Determine the total bitmap size of the block acknowledgment frame based on the number of consecutively received packets acknowledged from the block acknowledgment request frame and the maximum number of fragmented packets; Determine the size of the bitmap to be allocated to each sequence number SN level packet; Determine the number of bits to be padded; Configure the bitmap by determining the total bitmap size, the determined bitmap size to be allocated to each SN-level packet, and the determined number of bits to be padded; Configuration includes a bitmapped block acknowledgment frame, Wherein, the bitmap includes bits representing reception results of packets received from the sender. 2. The method of claim 1, wherein the total bitmap size is calculated by the following equation: Total bitmap size = ceiling[m×n/8] octets where ceiling[x] represents the smallest integer over 'x', the variable 'm' is the number of consecutively received packets, and the variable 'n' is the maximum number of fragmented packets, Here, the variable 'm' and the variable 'n' are determined from the block acknowledgment request frame. 3. The method of claim 2, wherein the bitmap of the block acknowledgment comprises a plurality of respective bitmaps for the successively received packets, and each respective bitmap corresponding to each of the successively received packets The size of is determined to be n bits. 4. The method of claim 3, wherein a number of bits from the total bitmap size are padding bits, the number of padding bits being calculated by the following equation: ceiling[m×n/8]×8-m×n. 5. The method of claim 1, wherein each bit of the bitmap for block acknowledgment is set to '1' if the corresponding packet is received successfully, and for the block if the corresponding packet fails to be received. Each bit of the acknowledged bitmap is set to '0'. 6. The method of claim 1, wherein the information on the size of the bitmap is included in a control field of the block acknowledgment request frame.

Images