KR20050064719A - Transmission and receiving method in mobile communication system - Google Patents

Abstract

The present invention relates to a data transmission and reception method of a mobile communication system. According to the present invention, in consideration of the time-varying radio channel situation, the transmitter buffer manager divides the SDU, configures the PDU, and transmits the PDU to the receiver. The header information of the PDU transmitted from the receiver buffer manager is analyzed to assemble the SDU. In this way, even if the situation of the wireless channel at the time of initial transmission and the situation of the wireless channel at the time of retransmission are different, the first transmission amount and the second transmission amount can be made equal.

Description

Data transmission and reception method in mobile communication system {TRANSMISSION AND RECEIVING METHOD IN MOBILE COMMUNICATION SYSTEM}

The present invention relates to a transmission and reception buffer manager of a mobile communication system.

The transmission / reception buffer manager of the mobile communication system is located in a media access control (MAC) layer of the transceiver and performs SDU assembly related to SDU division and reception related to transmission of an input packet or service data unit (SDU).

In general, a PDU (Protocol Data Unit) is configured from an SDU input from the MAC layer. When a radio channel situation cannot transmit one SDU, an SDU split occurs and a PDU generated from the SDU split is reassembled in a receiver. In order to do this, a sequence number is assigned to each PDU.

In the mobile communication system, since a radio channel has a characteristic of changing in time, if an error occurs in a cyclic redundancy check (CRC) of a corresponding PDU passing through a radio channel of a receiver, the PDU must be retransmitted. That is, the receiver notifies the transmitter of the CRC error of the corresponding PDU, and the transmitter notified of a negative acknowledgment message (NACK) retransmits the corresponding PDU.

However, when the radio channel at the time of retransmission is different from the radio channel situation at the first transmission, the transmission amount in the first transmission and the transmission amount in the second transmission may be different. Therefore, a solution to this problem is needed for the SDU assembly of the receiver.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a SDU split transmission method and a PDU configuration method in a transmitter buffer manager and a method of assembling an SDU in a receiver buffer manager in consideration of a time-varying radio channel situation.

A data transmission method of a mobile communication system according to a feature of the present invention for achieving the above object is a method for transmitting data to a receiver through a wireless channel of a mobile communication system,

a) storing a service data unit (SDU) generated from each session of a higher layer in a transmission buffer connected to each session; b) dividing the SDU according to an Adaptive Modulation and Coding (AMC) option determined according to the situation of the radio channel; c) configuring a protocol data unit (PDU) for the SDU itself or the SDU partitioning; And d) transmitting the PDU to the receiver over the radio channel.

Further, after step d),

e) retransmitting the SDU or the SDU partition that has received an NACK (unacknowledge) from the receiver to the SDU itself, the SDU partition itself, or repartitioned to the receiver; And f) repeating the step e) to complete the transmission of the one SDU when all of the one SDU is acknowledged from the receiver.

The header of the PDU includes a sequence number (SN) indicating a unique number of an SDU for reassembly by the receiver, a fragment control (FC) indicating a location of an SDU partition, and a relative starting position and last position of the SDU partition within one SDU. SPs and EPs each indicating a location, P / Rs indicating initial transmission or retransmission, and data actually transmitted are included.

The FC is represented by 2 bits,

The SDU split has a value of 01 for the first SDU split in one SDU, 10 for the middle SDU split, 11 for the last SDU split, and 00 for the SDU itself.

C),

The entire SDU is configured as one PDU, the initial transmitting entity is configured as one PDU, or the retransmission entity is configured as one PDU.

Step e),

Retransmit the SDU or SDU fragment received the NACK (unacknowledge, unacknowledged) according to the initially transmitted temporal order to the receiver.

A data receiving method of a mobile communication system according to an aspect of the present invention is a method in which a receiver receives data transmitted by a transmitter of a mobile communication system through a wireless channel.

a) storing a PDU received from the transmitter via the radio channel in a reception buffer; b) analyzing header information of the PDU to determine whether an SDU corresponding to the PDU is an SDU split; c) confirming whether the SDU can be completed by combining with the SDU partition previously stored in the reception buffer if the result of the check is the SDU partition; d) configuring the SDU and adding the SDU to the SDU buffer if the corresponding SDU is the SDU itself or the SDU can be completed by dividing the SDU as a result of the checking in step b) or c); e) adding the PDU to the SDU partition buffer if the SDU partition cannot complete the SDU as a result of the checking in step c); And f) assembling the SDUs stored in the SDU buffer and delivering the SDUs to higher layers.

Step d),

i) searching for a location where the SDU partition is to be added to the SDU partition buffer through header information of the PDU; ii) If the SDU split is the first SDU split, check whether the unique number of the SDU split matches the unique number of the next SDU split, and determine whether the relative last position of the SDU split is immediately before the relative start position of the current SDU split. Determining whether the current SDU split is the last SDU split; And iii) constructing an SDU from the SDU partition and adding to the SDU buffer.

In step ii),

Add the PDU to the SDU partition buffer if the unique number of the SDU partition does not match the unique number of the next SDU partition, or if the relative last position of the SDU partition is not immediately before the relative start position of the current SDU partition;

If the current SDU split is not the last SDU split, the process returns to checking whether the unique number of the SDU split matches the unique number of the next SDU split.

In step ii),

If the SDU split is the last SDU split, check whether the unique number of the SDU split matches the unique number of the previous SDU split, check whether the relative starting position of the SDU split is immediately after the relative last position of the current SDU split, Make sure the SDU split is the first SDU split,

The PDU is added to the SDU partition buffer if the unique number of the SDU partition does not match the unique number of the previous SDU partition or if the relative starting position of the SDU partition is not immediately after the relative last position of the current SDU partition.

Further, in step ii),

If the current SDU split is not the first SDU split, returning to the step of checking whether the unique number of the SDU split matches the unique number of the previous SDU split,

If the SDU split is an intermediate SDU split, check whether the unique number of the SDU split matches the unique number of the next SDU split, check whether the relative last position of the SDU split is immediately before the relative start position of the current SDU split, Check that the SDU split is the last SDU split.

Further, in step ii),

Add the PDU to the SDU partition buffer if the unique number of the SDU partition does not match the unique number of the next SDU partition, or if the relative last position of the SDU partition is not immediately before the relative start position of the current SDU partition;

If the current SDU split is not the last SDU split, the process returns to checking whether the unique number of the SDU split matches the unique number of the previous SDU split.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

One of the mobile communication systems, the 3GPP Wideband-Code Division Multiple Access (WCDMA) Radio Link Control (RLC) protocol, the sender divides the data into a size suitable for transmitting data, and if an error occurs, the error is retransmitted. It has a function to correct. The receiving side also has a function of assembling the divided data.

This RLC layer is composed of three transmission modes: transparent mode, unacknowledged mode, and acknowledged mode.

The sender adds CRC bits to the data to detect whether an error has occurred, and the receiver uses these CRC bits to check whether an error has occurred, and discards the data if it detects an error. Treat it as not. As such, since the receiver does not transmit the CRC check result to the transmitter, the transmitter does not use the CRC check result.

Transparent mode does not have a retransmission function and transmits data as it is. That is, the transmitter divides and transmits the data into units that can transmit the data in the data divider, and the receiver assembles the data determined by the CRC check that there is no error in the data assembly.

The non-response mode has no retransmission function, and the transmitter divides the data into a size suitable for transmission by the data divider, and transmits by adding information that can be assembled to the header of the divided data using a header adder. In other words, the data order manager on the receiving side checks the sequence number in the header of the data determined to have been successfully received as a result of the CRC check to see if an error has occurred. Assemble the data and send the data to the upper layer immediately.

In response mode, the sender divides the received data into the appropriate size and retransmits any data to be resent. The receiving side checks the unique number in the header to check whether an error has occurred, and if the error occurs as a result of the check, the receiving side informs the transmitting side of the status information indicating what data was successfully received so that retransmission is performed. .

1 illustrates a transmitter and a receiver of a mobile communication system according to an embodiment of the present invention.

As shown in FIG. 1, the transmitter 100 and the receiver 200 of the mobile communication system include buffer managers 110 and 210 and buffers 120 and 220, respectively, and the transmitter 100 and the receiver 200. Is connected via a wireless channel 300. In addition, in FIG. 1, 130 represents a packet SDU delivered to the transmitter 100, and 230 represents an SDU made by the receiver 200.

The transmission buffer 120 and the buffer manager 110 in the transmitter 100 may be located in the MAC layer of the mobile communication system. SDUs generated from each session are delivered to a transmit buffer 120 connected to each session. The buffer manager 110 transmits the corresponding SDU without segmentation according to the AMC (Adaptive Modulation and Coding) option determined by the situation of the wireless channel 300, or transmits the entire SDU at once by the radio channel situation. If not, the buffer manager 100 may perform SDU partitioning.

The receiver 200 transmits the SDU or the SDU split transmitted from the transmitter 100 to the MAC upper layer. The SDU split transmitted from the transmitter 100 is temporarily stored in the reception buffer 220 and then made into a complete SDU 230 through the assembly process and transferred to the upper layer.

2 illustrates an SDU in a transmit buffer according to an embodiment of the invention.

As shown in FIG. 2, the transmission buffer 120 includes a first SDU 121, a second SDU 122, and a last SDU 123.

121a, 121b, 121c are SDU partitions used for initial transmission in the first SDU 121, 121a and 121c have received an NACK (unacknowledge) from the receiver 200, and 121b is an ACK from the receiver 200. (acknowledge).

122a indicates the SDU segmentation used for initial transmission in the second SDU 122. This is a case where the radio channel situation can transmit the entire SDU at once, and the SDU splitting itself becomes an SDU. 122a is a situation in which an ACK is received from the receiver 200.

123a, 123b, and 123c are SDU partitions used for initial transmission in the third SDU 123, where 123c receives a NACK from the receiver 200, and 123b receives an ACK. Also, 123a is an SDU split that has not yet been transmitted.

3A to 3D illustrate an initial transmission entity of an SDU according to an embodiment of the present invention.

As shown in FIG. 3A, the initial transmitting entity 410 in one SDU includes SDU partitions 411, 412, 413 that indicate the retransmitting entities used for retransmission.

413 receives an ACK at the receiver 200 and 412 receives a NACK. In addition, 411 indicates an SDU partition that has not been retransmitted yet.

Thereafter, the SDU segment 412 receiving the retransmission entity 413 and the NACK in the initial transmission entity 410 is retransmitted, 413 receives the ACK, and 412 receives the NACK.

3B shows a situation in which the retransmission entity 412 having received the NACK is retransmitted again, and the SDU partition 411 not yet retransmitted is retransmitted.

Here, 421, 422, 423, and 424 indicate SDU partitions used when retransmitting 411 and 412 of FIG. 3A, and each SDU partition is transmitted with a time difference. That is, 423 is transmitted before 422 and 422 is transmitted before 421. 423 and 421 received NACK at the receiver 200, and 422 received ACK.

In addition, FIG. 3C illustrates a situation in which the SDU partitions 421 and 423 having received the NACK in FIG. 3B are retransmitted.

In FIG. 3C, 431, 433, and 434 are SDU partitions used when retransmitting 421 and 423 of FIG. 3B, and each SDU partition is transmitted with a time difference. That is, 434 is sent before 433 and 433 is sent before 431. Here, 431 and 433 have received an ACK, and 434 is an SDU division having received the NACK.

In addition, FIG. 3D illustrates a situation in which 434 having received the NACK in FIG. 3C is retransmitted and finally received the ACK. As such, the transmission of one initial transmitting entity 410 within one SDU is completed.

4A to 4B illustrate a method of configuring a PDU when transmitting an SDU or an SDU partition according to an AMC option according to an embodiment of the present invention, and FIG. 4A illustrates one SDU, initial transmission entities in an SDU, and retransmission entities. 4b shows the contents included in the PDU header.

In FIG. 4B, the SN 521 represents a sequence number, which is uniquely assigned to the initial transmitting entity. FC 522 is a Fragment Control, which is a value represented by 2 bits and has a value of 01 for the first SDU split, 10 for the middle SDU split, and 11 for the last SDU split within one SDU. The value has a value of 00 if the entire SDU (not the SDU split).

The SP 523 indicates the relative starting position of the SDU splitting constituting the initial transmission entity or retransmission entity included in the payload 526 within one SDU, and the EP 524 shows Payload within one SDU. It indicates the relative last position of the SDU splitting constituting the initial transmission entity or retransmission entity included in 526.

The P / R 525 is a value represented by 1 bit, and is set to 1 for an initial transmission entity and 0 for a retransmission entity. Payload 526 represents the data of the initial transmitting entity and the retransmitting entity.

In addition, in FIG. 4A, 510 represents one SDU, and 511, 512, and 513 represent initial transmission entities used for initial transmission of the SDU 510. In addition, 514 indicates the size of the SDU 510, and the unit is N bytes (N> = 1).

A method of configuring a PDU from an SDU according to an embodiment of the present invention having such a configuration is as follows.

The first method is a method of configuring the entire SDU as one PDU, and may be applied when the AMC option can configure the entire SDU as one PDU payload. According to this method, the PDU of FIG. 4B is configured as shown in FIG. 5A.

That is, since the SDU is the SDU itself, the FC value is 00, the SP is 1, which is the starting position, and the EP is 35, which is the size of the SDU. In addition, since the SDU is an initial transmission entity, the P / R is 1.

The second method is a method of configuring an initial transmission entity as one PDU, and may be applied when the AMC option cannot configure the entire SDU as one PDU payload. That is, this method is used when transmitting 511, 512, and 513 in FIG. 4A, and the PDUs of FIG. 4B are configured as shown in FIG. 5B for 511, 512, and 513, respectively.

That is, the PDU for 513 shows that the SDU is the first SDU split, so the FC value is 01, the SP is 1, the start position of the SDU split, and the EP is 21, the end of the SDU split.

Looking at the PDU for 512, the SDU is the second SDU split, so the FC value is 10, which represents the middle SDU split, and the SP is 22, the start of the SDU split and immediately after the first SDU split. Becomes 30, which is the end of the SDU split. In addition, the unique number SN becomes a value (x + 1) that is one greater than x, which is a unique number of the first SDU partition.

Finally, if you look at the PDU for 513, the SDU is the last SDU split, so the FC value is 11, which represents the last SDU split, and the SP is 31, the start of the SDU split and immediately after the second SDU split. The EP will be 35, the end of the SDU. In addition, the unique number SN becomes (x + 2), which is one greater than the unique number of the second SDU division.

Also, since 511, 512, and 513 are SDU splits for the initial transmitting entity, the P / R values are all 1.

The third method is to configure a retransmission entity as one PDU. This method can be applied when retransmitting an initial transmission entity that has received a NACK. In FIG. 4A, when the SDU partitioning 513 receives a NACK, 515 is the first retransmission entity and 516 is the fourth retransmission entity for retransmission. PDU is configured as shown in FIG. 5C.

That is, the PDU for 516 shows that the SDU is the first SDU split, so the FC value is 01, the SP is 1, the start position of the SDU split, and the EP is 8, the end of the SDU split.

In addition, when looking at the PDU for 515, since the SDU is the fourth SDU split, the FC value is 10 indicating the intermediate SDU split, the SP is 14, the start position of the SDU split, and the EP is the end of the SDU split. It becomes 16. Further, since 516 and 515 are SDU partitions of 513, which are SDU partitions, the unique number SN becomes x equal to SDU partition 513. Also, since 516 and 515 are SDU splits for the retransmission entity, the P / R values are all zero.

6A illustrates an SDU assembling method in the buffer manager 210 of the receiver 200 according to an exemplary embodiment of the present invention, and illustrates a process of assembling the SDU in the receiver's buffer manager when an arbitrary PDU is received.

First, when the PDU arrives at the buffer manager 210 of the receiver 200 (S601), it is checked whether the received PDU is an SDU split (S602). If it is determined that the SDU is not divided (that is, the SDU itself), the corresponding SDU is added to the SDU buffer (S605).

In addition, if it is determined that the SDU partition is determined, it is determined whether the SDU can be completed by the SDU partitions in the existing SDU partition buffer and the corresponding SDU (S603).

If it is determined that the SDU can be completed, the SDU is configured and the corresponding SDU is added to the SDU buffer (S605). At this time, the SDU partitions that constitute the SDU are deleted from the SDU partition buffer.

In addition, if it is determined that the SDU cannot be completed, the corresponding PDU is added to the SDU partition buffer and all operations are terminated (S604).

6B is a detailed process of checking whether the SDU can be completed by the received PDUs and the SDU partitions in the existing SDU partition buffer in steps S603 to S605 of FIG. 6A, and accordingly adding the SDU or PDU to the SDU partition buffer. It is shown.

first. In step S621, the position where the received PDU is added to the SDU split buffer is searched. After searching the location, check the FC value and check the SN, EP (or SP) value according to each FC value to check the complete SDU configuration, and add the SDU or PDU to the SDU partition buffer according to the check result. do.

That is, if FC = 01 (if the corresponding SDU split is the first SDU split) (S622), it is checked whether the unique number (SN) of the corresponding SDU split matches the unique number of the next SDU split (S623). As a result of the check, if the unique numbers match, it is checked whether the relative last position (EP) of the SDU segment is just before the relative start position of the current SDU segment (SP-1) (S624). If the result of the check matches, it is checked whether the current SDU split is the last SDU split (S625), and if the last SDU split, the SDU is configured from the corresponding SDU split and added to the SDU buffer (S626, same as step S605 of FIG. 6A).

If the unique number of the corresponding SDU partition does not match the unique number of the next SDU partition as determined in step S623, or if the relative last position of the corresponding SDU partition is not immediately before the relative start position of the current SDU partition as a result of checking in step S624, the SDU partition buffer Add the corresponding PDU (S634, same as step 604 of FIG. 6A). In addition, as a result of checking in step S625, if the current SDU split is not the last SDU split, the process returns to step S623.

Meanwhile, as a result of checking in step S622, whether the corresponding SDU split is not the first SDU split or not is determined as the last SDU split (S627). If the check result is the last SDU split, it is checked whether the unique number of the corresponding SDU split matches the unique number of the previous SDU split (S628). As a result of the identification, if the unique numbers match, it is checked whether the relative starting position of the corresponding SDU segment is immediately after the relative last position of the current SDU segment (S629). If the result of the check matches, it is checked whether the current SDU split is the first SDU split (S630). If the split is the first SDU split, the process proceeds to step S626 to configure an SDU from the corresponding SDU split and adds the SDU to the SDU buffer.

If the unique number of the corresponding SDU split does not match the unique number of the previous SDU split, or if the relative starting position of the corresponding SDU split is not immediately after the relative last position of the current SDU split, the procedure proceeds to step S634. Add the corresponding PDU to the SDU partition buffer. In addition, if the current SDU split is not the first SDU split as a result of checking in step S630, the process returns to step S628.

Meanwhile, as a result of checking in step S627, if the corresponding SDU split is not the last SDU split, it is checked whether the unique number of the corresponding SDU split matches the unique number of the next SDU split (S631). As a result of the check, if the unique numbers match, it is checked whether the relative last position of the corresponding SDU segment is immediately before the relative start position of the current SDU segment (S632). If the result of the check matches, it is checked whether the current SDU split is the last SDU split (S633). If the split is the last SDU split, the process moves to step S628.

In addition, if the unique number of the corresponding SDU partition does not match with the unique number of the next SDU partition as a result of checking in step S631, or if the relative last position of the corresponding SDU partition is not immediately before the relative starting position of the current SDU partition in step S632. Go to the step to add the PDU to the SDU partition buffer.

The receiver assembles the SDU from the SDU division according to the above process, and delivers the assembled SDU to the upper layer.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited thereto, and various other changes and modifications are possible.

As described above, when the SDU split transmission method in the transmitter and the SDU assembly method in the receiver according to the present invention are applied, the situation of the radio channel at the initial transmission time and the situation of the radio channel at the retransmission time are different. The first transmission amount and the second transmission amount can be the same.

1 is a diagram showing the configuration of a transmitter and a receiver of a mobile communication system according to an embodiment of the present invention.

2 is a diagram illustrating a configuration of an SDU in a transmission buffer according to an embodiment of the present invention.

3A to 3D are diagrams illustrating a configuration of an initial transmission entity of an SDU according to an embodiment of the present invention.

4A to 4B illustrate a method of configuring a PDU when transmitting an SDU or an SDU partition according to an AMC option according to an embodiment of the present invention.

5A to 5C are diagrams illustrating an example of a PDU configuration for the SDU or the SDU division of FIG. 4.

6A and 6B are diagrams illustrating an SDU assembly method in a buffer manager of a receiver according to an embodiment of the present invention.

Claims (16)

A method of transmitting data to a receiver through a wireless channel by a transmitter of a mobile communication system, a) storing a service data unit (SDU) generated from each session of a higher layer in a transmission buffer connected to each session; b) dividing the SDU according to an Adaptive Modulation and Coding (AMC) option determined according to the situation of the radio channel; c) configuring a protocol data unit (PDU) for the SDU itself or the SDU partitioning; And d) transmitting the PDU to the receiver via the radio channel Data transmission method of the mobile communication system comprising a. The method of claim 1, After step d), e) retransmitting the SDU or the SDU partition that has received an NACK (unacknowledge) from the receiver to the SDU itself, the SDU partition itself, or repartitioned to the receiver; And f) repeating step e) to complete the transmission of one SDU when all of the one SDU is received from the receiver by acknowledgment (ACK); The data transmission method of the mobile communication system further comprising. The method of claim 1, The header of the PDU includes a sequence number (SN) indicating a unique number of an SDU for reassembly by the receiver, a fragment control (FC) indicating a location of an SDU partition, and a relative starting position and last position of the SDU partition within one SDU. SP and EP each indicating a location, P / R indicating whether the initial transmission or retransmission, and the actual transmitted data Method of transmitting data in a mobile communication system. The method of claim 3, The FC is represented by 2 bits, The SDU split has a value of 01 for the first SDU split in one SDU, 10 for the middle SDU split, 11 for the last SDU split, and 00 for the SDU itself. Method of transmitting data in a mobile communication system. The method of claim 1, C), Or configure the entire SDU as a single PDU, Configure the initial transport entity into one PDU, or Configure the retransmission entity as a single PDU Method of transmitting data in a mobile communication system. The method of claim 2, Step e), Retransmitting the unacknowledged (NACK) or the SDU segment received to the receiver according to the initially transmitted temporal order. Method of transmitting data in a mobile communication system. In the method for receiving a data transmitted by a transmitter of a mobile communication system via a wireless channel, a) storing a PDU received from the transmitter via the radio channel in a reception buffer; b) analyzing header information of the PDU to determine whether an SDU corresponding to the PDU is an SDU split; c) confirming whether the SDU can be completed by combining with the SDU partition previously stored in the reception buffer if the result of the check is the SDU partition; d) configuring the SDU and adding the SDU to the SDU buffer if the corresponding SDU is the SDU itself or the SDU can be completed by dividing the SDU as a result of the checking in step b) or c); e) adding the PDU to the SDU partition buffer if the SDU partition cannot complete the SDU as a result of the checking in step c); And f) assembling the SDU stored in the SDU buffer and delivering the SDU to a higher layer Data receiving method of the mobile communication system comprising a. The method of claim 7, wherein Step d), i) searching for a location where the SDU partition is to be added to the SDU partition buffer through header information of the PDU; ii) If the SDU split is the first SDU split, check whether the unique number of the SDU split matches the unique number of the next SDU split, and determine whether the relative last position of the SDU split is immediately before the relative start position of the current SDU split. Determining whether the current SDU split is the last SDU split; And iii) constructing an SDU from the SDU partitioning and adding to the SDU buffer Data receiving method of the mobile communication system comprising a. The method of claim 8, In step ii), Adding the PDU to the SDU partition buffer if the unique number of the SDU partition does not match the unique number of the next SDU partition, or if the relative last position of the SDU partition is not immediately before the relative start position of the current SDU partition. Method of receiving data in mobile communication system. The method of claim 8, In step ii), If the current SDU split is not the last SDU split, returning to the step of checking whether the unique number of the SDU split matches the unique number of the next SDU split. Method of receiving data in mobile communication system. The method of claim 8, In step ii), If the SDU split is the last SDU split, check whether the unique number of the SDU split matches the unique number of the previous SDU split, check whether the relative starting position of the SDU split is immediately after the relative last position of the current SDU split, To check if the SDU split is the first SDU split Method of receiving data in mobile communication system. The method of claim 11, In step ii), Adding the PDU to the SDU partition buffer if the unique number of the SDU partition does not match the unique number of the previous SDU partition, or if the relative starting position of the SDU partition is not immediately after the relative last position of the current SDU partition. Method of receiving data in mobile communication system. The method of claim 11, In step ii), If the current SDU split is not the first SDU split, returning to the step of checking whether the unique number of the SDU split matches the unique number of the previous SDU split. Method of receiving data in mobile communication system. The method of claim 8, In step ii), If the SDU split is an intermediate SDU split, check whether the unique number of the SDU split matches the unique number of the next SDU split, check whether the relative last position of the SDU split is immediately before the relative start position of the current SDU split, To check if the SDU split is the last SDU split Method of receiving data in mobile communication system. The method of claim 14, In step ii), Adding the PDU to the SDU partition buffer if the unique number of the SDU partition does not match the unique number of the next SDU partition, or if the relative last position of the SDU partition is not immediately before the relative start position of the current SDU partition. Method of receiving data in mobile communication system. The method of claim 14, In step ii), If the current SDU split is not the last SDU split, returning to the step of checking whether the unique number of the SDU split matches the unique number of the previous SDU split. Method of receiving data in mobile communication system.