Method and device to transfer service with application of reordering by packet data convergence protocol (pdcp) in system of mobile communication

Background Art relating to the invention

1. Field of the Invention

The present invention relates to a mobile communication system, and in particular to a method and apparatus for supporting handover between cells, when a user device (UE) performs packet reordering repeated.

2. Description of Related Art

Universal Mobile Telecommunications System (UMTS) is the asynchronous mobile communication 3rd generation (3G), which uses wideband code division multiple access (CDMA) systems and is based on Global System for Mobile Communications (GSM) and General Packet Radio Service ( GPRS), which are European mobile communication systems. The UMTS system is an example of cellular mobile communication systems, each of which includes a plurality of cells for which the total is divided service area of ​​the system and supports handover between cells to provide a continuous connection.

When an active UE moves from one cell (source cell) to another cell (target cell), the target cell establishes a communication channel for the UE, and restores objects of each level, associated with the establishment of the link. In particular, when the communication performed by UE, supports an automatic retransmission request (ARQ), the target cell may sometimes be necessary to restore ARQ entity for the UE. In the present application, handover restoring ARQ entity, refers to handover in which the source cell removes used therein existing ARQ and the target cell sets a new ARQ entity.

When a conventional mobile communication system, a handover is performed, the restoring ARQ object, object of a higher level object stored performs ARQ retransmission. Accumulated retransmission can reduce the complexity of a higher level, although the packets already transmitted in the source cell may be retransmitted in the target cell. In a conventional mobile communication system UMTS handover restoring ARQ entity, it takes place during the movement of a serving radio network subsystem (SRNS), during which changes RNC (RNC) to the UE. Because the SRNS relocation occurs less frequently when the accumulated retransmission taking into account the complexity rather than efficiency.

At the same time Partnership Project 3rd generation (3GPP), which is responsible for the standardization of UMTS, active discussion about the long-term development (LTE) of the UMTS system as an advanced mobile communication system of the UMTS system. LTE is a technology that aims at its commercial use by 2010 and the realization of high-speed packet communication rate of about 100 Mbit / s. To this end, various schemes are discussed, which include a scheme of reducing the number of nodes located on a communication path by simplifying the network structure and circuitry maximum approaching a wireless protocol to a wireless channel.

In a developed mobile communication system, such as the LTE system, ARQ entity is located in a node B, which is a lower-level object RNC. Therefore ARQ entity is always restored upon handover between nodes B, and thus, in a developed mobile communication system, such as the LTE system, handover restoring ARQ entity, occurs much more frequently than in the UMTS. It is therefore necessary to develop technology to improve communication efficiency in handover, reducing ARQ entity, in a developed mobile communication system such as an LTE system.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been devised to solve the above problems existing in the prior art and the present invention provides a method and apparatus for improving communication efficiency in handover, reducing object ARQ, in a mobile communication system.

Furthermore, the present invention provides a method and apparatus for preventing loss or repeated transmission of data packets in handover, reducing ARQ entity.

Furthermore, the present invention provides a method and apparatus for reordering higher-level object ARQ, which can realize the selective retransmission of packets not received in a source cell when a UE moved to a target cell.

In accordance with one aspect of the present invention, a method for performing a handover user equipment (UE) in a mobile communication system, the method includes transmitting the first packet data blocks (PDU) on packet data convergence protocol (PDCP), correctly received from the source cell, together with a special indication requiring reordering of the first PDCP PDU, the receiving buffer of the radio link control (RLC) PDCP receiving entity, when receiving a command message from a handover source cell to a target cell; in response to a specific component, buffering first PDCP PDU in the PDCP PDU reordering buffer by using PDCP receiving entity; and when from the target cell through a new RLC receiving entity for the target cell receives the second PDU PDCP, the issuance of the PDCP reordering buffer to the third PDU PDCP PDU PDCP before the first lost PDU PDCP, whose sequence number higher than the sequence number of the second PDU PDCP.

In accordance with another aspect of the present invention there is provided apparatus UE for performing a handover in a mobile communication system, wherein this equipment UE includes existing receiving entity RLC receiving units PDU RLC from the source cell and assembling the blocks PDU RLC into blocks PDU PDCP before the handover and outputting first PDCP PDU, correctly received from the source cell, together with a special indication requiring reordering of the first PDCP PDU, when receiving a command message from a handover source cell to a target cell; a new RLC receiving entity for receiving from the target cell after the handover to one or multiple RLC PDU, containing a second PDCP PDU, which has not been correctly received from the source cell and assembling the received RLC PDU in the second PDCP PDU; and the receiving PDCP entity for buffering the first PDU PDCP buffer reordering PDU PDCP in response to a specific component and outputting from the buffer reordering PDU PDCP third PDU PDCP before PDU PDCP before the first lost PDU PDCP, whose sequence number higher than the sequence number of the second PDU PDCP, when the second PDCP PDU received from the new RLC receiving entity.

In accordance with another aspect of the present invention, a method for performing a handover Evolved Node B (ENB) in a mobile communication system, the method includes receiving a target ENB, controlling the target cell from the source ENB first PDU PDCP, which were not correctly received UE from source ENB, controlling a source cell due to handover of the UE from the source cell to the target cell; transmitting the second PDU PDCP with the first indication from the target ENB to the UE, wherein the second PDU PDCP include other PDU PDCP of the first PDU PDCP except the last PDU PDCP of the first PDU PDCP, which is the first indication that each of the second PDU PDCP is not the last PDCP PDU, transmitted from a source cell to a target cell; and transmitting the last PDCP PDU from the target ENB to the UE together with a second indication that the last PDCP PDU is the last PDCP PDU, transmitted from the source cell to the target cell.

In accordance with another aspect of the present invention there is provided apparatus enhanced node B (ENB) for performing handover in a mobile communication system, the apparatus ENB includes a transmission buffer for storing first PDU PDCP, transmitted from the source ENB, controlling a source cell and storing PDCP PDU, transmitted from the node joining, the UE does not adopt the correct first PDCP PDU from the source ENB due to handover of the UE from the source cell to the target cell; and a control unit for controlling the send buffer such that the transmission buffer to transmit a second PDU PDCP with the first indication to the UE and the last PDU PDCP together with a second indication to the UE, second PDU PDCP included the remaining PDU PDCP of the first PDU PDCP except the last PDU PDCP of the first PDU PDCP, wherein the first indicator indicates that each of the second PDU PDCP is not the last PDU PDCP, transmitted from the source cell to the target cell, the second indicator indicates that the last PDU PDCP is the last PDU PDCP, transmitted from the source cell to target cell.

LIST OF FIGURES

The above and other aspects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 - a general view of the structure of LTE mobile communication system;

FIG. 2 illustrates a protocol stack LTE mobile communication system;

FIG. 3 illustrates an operation of an RLC layer in a mobile communication system;

FIG. 4 - the block sequence diagram illustrating a handover process, the restoring ARQ entity, when a UE moves to a new cell belonging to another ENB;

FIG. 5 - a block diagram of a messaging illustrating an example of the overall process according to the present invention;

FIG. 6 - a block diagram illustrating a process of RLC reception by the UE according to the present invention;

FIG. 7 - block-diagram illustrating the operation of PDCP receiving entity according to the present invention;

FIG. 8 illustrates an example of RLC control information according to the present invention;

FIG. 9 - a block diagram of a messaging illustrating an example of the overall process according to the present invention;

FIG. 10 shows a block diagram illustrating a process of RLC reception by the UE according to the present invention;

FIG. 11 - a block diagram illustrating the operation of PDCP receiving entity according to the present invention; and

FIG. 12 - a block diagram illustrating structures of transmitting / receiving entities according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Next, a preferred embodiment of the present invention with reference to the accompanying drawings. In the following description, a detailed description is omitted known functions and configurations if it can obscure the present invention. The main object of the present invention is to prevent repeated transmission of data packets by using selective retransmission when handover reducing ARQ entity. Currently, proper operation of reordering received packets performs higher level object of the object ARQ, so that selectively retransmitted packets are received at a higher level in the same order in which the packets were originally transmitted.

As an illustrative example embodiments of the present invention will be briefly described LTE system.

As shown in FIG. 1 developed a radio access network UMTS (E-RAN) 110 or 112 has a simplified two node structure, which includes enhanced nodes B (ENB) 120, 122, 124, 126 and 128 and nodes 130 and 132 joining. Through the E-RAN 110 and 112 with the network 114 of the Internet Protocol (IP) is connected to a user device (UE) 101.

ENB 120-128 correspond to the currently available nodes B of the UMTS system and are connected to UE 101 over a wireless communication channel. ENB 120-128 perform scheduling by collecting information about the situation and perform the functions related to the management of radio resources. For example, it provided ENB management protocol such as radio resource control protocol (RRC).

To realize the maximum transmission rate of 100 Mbit / s used as an LTE wireless access technology multiplexing scheme, an orthogonal frequency division multiplexing (OFDM) in a system bandwidth of 20 MHz. Moreover, the LTE system uses an Adaptive Modulation and Coding (AMC), which determines a modulation scheme and a channel coding rate according to channel status of the UE device.

As shown in FIG. 2 levels of 205 and 240 Packet Data Convergence Protocol (PDCP) perform actions such as compression / decompression and encryption / decryption IP-header, thereby generating packet data units PDCP (PDU). In this application, issuing a package of object specific protocol called Protocol PDU. Each of the levels 210 and 235 of a radio link control (RLC) performs the function of object ARQ, which reconstructs PDCP PDU into RLC PDU units, each of which has a proper size and performs an ARQ blocks over these RLC PDU. Levels 205 and 240 PDCP and levels 210 and 235 of the RLC construct at least one PDCP entity or at least one object RLC, which may be constructed according to each service or flow when establishing the connection, and process the data packets passing through each object . As shown in FIG. 2, the levels 205 and 240, respectively PDCP located in the UE and the node connection, and levels 210 and RLC 235 are located respectively in the UE and the ENB.

To set the RLC entity attached levels 215 and 230 level medium access control (MAC), which performs multiplexing of RLC PDU units in a MAC PDU and demultiplexing the MAC PDU into RLC PDU units. Physical layers 220 and 225 generate OFDM symbols, channel coding and modulating higher layer data and transmit the generated OFDM symbols through a wireless communication channel or perform demodulation and channel decoding OFDM symbols, the received wireless data channel, and transmit the OFDM symbols to a higher level. Most of the operations of the hybrid ARQ (HARQ), such as decoding of received packets, soft combining of packets with previously received packets, CRC calculation, etc., is performed on the physical layers 220 and 225, levels 215 and 230, and MAC control operations of the HARQ.

As described above, the levels 210 and 235 of the RLC provide reliable data transmission / reception through the ARQ process. Based on the above object of the RLC layer is called the object of ARQ.

As shown in FIG. 3, the transmission buffer 305 in the RLC layer from the transmitter stores PDCP PDU blocks 310 and 312, the RLC layer provided on the transmitter side, before transmitting the PDCP PDU units RLC layer at the receiver side. Each of the blocks PDCP PDU includes encrypted IP-compressed header packet as a payload and includes a PDCP sequence number, sequentially increasing by one in a header. The sequence number corresponds to the "input value changing according to each packet," which is used to encrypt and decrypt IP-packet. In most currently known encryption schemes reliability is improved by using the "input value changing according to each packet" when a ciphering apparatus ciphers package. Blocks PDU PDCP 310 and 312 are restored into blocks PDU RLC, each of which has a proper size, the module 315 framing, sequence numbers of RLC, increasing consecutive unit, attached to the reconstructed blocks PDU RLC, and the blocks PDU RLC transmitted RLC layer side receiver. The blocks are buffered in the RLC PDU buffer 320 retransmission when an RLC of the receiver side receives the confirmation signal (ACK).

The RLC layer of the receiver side stores the received RLC PDU units in the receiving buffer 303, detects RLC PDU units, lost during the transmission by checking each sequence number, and makes a request for retransmission of RLC PDU units, lost during transmission, RLC layer of the transmitter side. Further, for convenience of description, RLC PDU [x] means the RLC PDU with RLC sequence number, equal to x, and PDCP PDU [x] means the PDCP PDU with PDCP sequence number, equal to x.

The following describes an example of ARQ operation, performed by the level RLC. At some point in time of the blocks of between PDU RLC [7] through PDU RLC [10] transmitted from the RLC layer at the transmitter side have been taken by the RLC layer at the receiver side and stored in a buffer 330 receiving only PDU RLC [8], and PDU RLC [9]. The RLC layer of the receiver-side RLC layer replies to the transmitter sending a message about the status of 340, which reported on the correct reception of blocks PDU RLC [8] and PDU RLC [9] and the unsuccessful reception unit PDU RLC [7]. More specifically, a status message 340 includes a signal ACK [8,9], which is an ACK signal, comprising the sequence numbers 8 and 9, and the signal NACK [7], which is a NACK signal, including a sequence number of 7. Then RLC layer of the transmitter side retransmits RLC PDU [7], which is stored in the buffer 320 and retransmission is requested for retransmission, and removes correctly transmitted RLC PDU [8] and RLC PDU [9] from retransmission buffer 320. From among the RLC PDU blocks, stored in the reception buffer 330, RLC PDU, the ability to form one complete PDCP PDU, PDCP PDU are prepared in a reassembly module 335, and created PDCP PDU is then transmitted to a PDCP layer at the receiver side.

One important feature of the operation performed by the level RLC, is that the RLC layer at the receiving RLC delivers blocks PDU PDCP PDCP layer at the receiver side, the RLC layer on the side of the transmitter delivers blocks PDU PDCP in the same order as the RLC layer transmitter-side PDCP PDU blocks received from the PDCP layer at the transmitter side. This operation is called "delivery order". For example, even though the PDU RLC [101] 310 can be collected using PDU RLC [8], and PDU RLC [9], the RLC layer at the receiver does not collect PDU RLC [8], and PDU RLC [9] in the PDU RLC [ 101] 310 and deliver the collected RLC PDU [101] 310 level PDCP, RLC layer because the receiver-side has not received RLC PDU [7]. When the RLC layer at the receiver side receives the retransmitted PDU RLC [7] and a buffer 330 receiving the longer contains the missed PDU RLC, the block 335 assembling an RLC at the receiver constructs a PDU PDCP by collecting units PDU RLC, stored in the buffer 330 receive and deliver engineered PDCP PDU PDCP layer at the receiver side.

Since, as described above, the RLC layer provides the function of reliable transmission / reception function and a "delivery order" PDCP layer does not require a separate buffering or sequence reordering function. However, when a UE performs handover to a cell belonging to another ENB, UE should remove an object ARQ (that is, a RLC), used in a previous cell and should restore the RLC entity, used in the new cell. Therefore, prior to completion of the handover, the RLC layer may be unable to provide the "order of delivery" function and reliable transmission / reception through the ARQ operation.

As shown in FIG. 4, UE 405 includes a receiving PDCP entity and a receiving entity RLC, and both source ENB 410 controlling a source cell and a target ENB 415 controlling a target cell include transmitting entity RLC, and node 420 joining comprises transmitting entity PDCP.

As shown in FIG. 4, the transfer units RLC PDU between the UE 405 and source ENB 410 (step 425), source ENB 410 determines whether the handover UE 405 to a cell of the target ENB 415 (step 430). When source ENB 410 requests target ENB 415 to prepare itself for the handover (step 435), target ENB 405 performs cooking which enable UE 405 to immediately resume communication after the handover to target ENB 415, for example, target ENB 405 sets the UE 405 RLC entity (step 440) and then informs the source ENB 410 of the completion of preparation (step 445). Then, source ENB 410 stops transmission to the UE 405 on the downlink (step 447) and instructs the UE 405 to perform handover to target ENB 415 (step 450). In this case, data transmission / reception and the time the team is based on the following assumptions.

- Node 420 joining handed source ENB blocks PDU PDCP [1] on the PDU PDCP [8].

- Source ENB 410 transmits to the UE 405 RLC PDU units, units corresponding to PDCP PDU [1] to PDCP PDU [8]. Blocks PDCP PDU [7] and PDCP PDU [8] have not yet transmitted.

- From among the RLC PDU units UE 405 has correctly received RLC PDU, the corresponding PDCP PDU [1], PDCP PDU [2], PDCP PDU [4] and PDCP PDU [6] (step 449).

- UE 405 informs the source ENB 410 through the RLC status report, the UE 405 has correctly received RLC PDU, the corresponding PDCP PDU [1] and PDCP PDU [2].

- From among the blocks arranged in order of UE RLC PDU 405 collects PDCP PDU [1] and PDCP PDU [2] and delivers the assembled PDU to PDCP receiving entity.

- RLC receiving entity of the UE 405 stores RLC PDU units, corresponding to PDCP PDU [4] and PDCP PDU [6].

Source ENB 410 delivers to the target ENB 415 blocks PDU PDCP [3] on the PDU PDCP [6], which have not yet been received from the UE 405 an ACK signal level RLC, and blocks PDU PDCP [7], and PDU PDCP [8], which not yet transmitted to the UE 405 (step 455).

After receiving the handover UE 405 deletes these blocks are not in order of the RLC PDU reception buffer and removes the existing RLC entity (RLC entity, in communication with the source cell). Then, together with the existing RLC entity RLC PDU units are deleted, the corresponding PDCP PDU [4] and PDCP PDU [6] (step 460). Thereafter, UE 405 performs handover to target ENB 415, and then creates a new RLC entity for communication with target ENB 415 and transmits a handover complete to the target node 415 (step 465). Post the completion of the handover includes sequence numbers of correctly received blocks PDU PDCP. For example, since the PDCP receiving entity of the UE 405 has correctly received PDCP PDU [1] and PDCP PDU [2], a completion message transmission service includes information indicating blocks that have been received up to PDCP PDU block PDCP PDU [2].

Upon receiving the target ENB 415 reports completion of handover to the target ENB 415 transmits a request node 420 joining to change the data path for the downlink, since UE 405 to perform handover (step 467) and decides whether to retransmit the block with the PDU PDCP [3 ] on PDCP PDU [6], which PDCP receiving entity of the UE 405 has not received, from among PDCP PDU blocks, received from source ENB 410, by using the RLC object, the newly created for the UE 405 (step 480). In response to the request from target ENB 415 node 420 joining switches data path for the downlink to the UE 405 from source ENB 410 to target ENB 415 and transmits a target ENB 415 subsequent blocks PDU PDCP, delivered to source ENB 410, that is, blocks PDU PDCP [9] on PDCP PDU [11]. Meanwhile, target ENB 415 transmits PDCP PDU unit [3] and the following blocks PDCP PDU the UE 450 using the newly created object RLC.

As shown in FIG. 4, when target ENB 415 resumes transmission units PDU PDCP, starting with block PDU PDCP, following ordered in order of blocks PDU PDCP, then, despite the possibility that the transmission may be a retransmission, the receiving PDCP entity does not need any separately buffer the received PDCP PDU blocks, blocks or reorder PDCP PDU. Thus, the PDCP receiving entity immediately inputs PDCP PDU blocks, delivered from the RLC receiving entity, the object of decoding and decompressing the header object.

However, if the target ENB transmits only the PDCP PDU units, which a UE has not received, while PDCP PDU units require separate buffering and reordering. Reordering is reordering operation received packets according to their sequence numbers and then delivering the reordered packets subsequent processing module simultaneously storing these packets out of order as long as they will not next in order as a result of the reordering. In this case, under the following out of order package is meant the presence of a missing packet (ie not yet received packet). In other words, when there is a missing packet, packets with sequence numbers higher than the sequence number of the missing packet is considered packages, not following the order. Object reordering temporarily stores these packets out of order or until until the missing packet is received or until until it is concluded that the missing packet is missing completely. The effectiveness of the operation reordering depends on how quickly you can find the missing packet loss and deliver packages with serial numbers higher than the sequence number of the missing packet the next processing unit when it is concluded that the missing package is lost permanently.

According to a first embodiment of the present invention, the receiving PDCP entity of the UE temporarily stores the receive buffer following not consecutive blocks PDU PDCP among blocks PDU PDCP, of correctly received from the source ENB, and when it receives PDU PDCP of the target cell, the receiving PDCP entity determines reordering a sequence of blocks that PDCP PDU, having a sequence number less than the ordinal number of the received PDCP PDU, has been completed. This is based on the fact that the receiving RLC entity of the UE performs a "delivery order" and therefore welcome the receiving PDCP entity unit PDU PDCP with serial number x implies that the receiving PDCP entity can not receive another PDU PDCP with a serial number less x.

As shown in FIG. 5, before receiving the handover command from source ENB 510, UE 505 receives, from the source ENB 510 units PDU RLC, corresponding PDU PDCP [1], PDU PDCP [2], PDU PDCP [4], and PDU PDCP [6] (step 520 ). Because of the number of blocks PDU RLC, blocks PDU RLC, corresponding PDU PDCP [1], and PDU PDCP [2] are already following the order, they are collected in the PDU PDCP [1], and PDU PDCP [2], which is then first delivered PDCP receiving entity.

When the UE 505 receives, from the source ENB 510, the handover command (step 525), UE assembles all the PDU RLC, which can be collected from a number of blocks PDU RLC, remaining in the reception buffer RLC, a PDU, PDCP, and then delivers the assembled blocks PDU PDCP PDCP receiving entity (step 530). This blocks PDU PDCP [4] and PDU PDCP [6], which are considered to be accepted properly delivered to the receiving entity PDCP. In addition, the receiving RLC entity of the UE 505 delivers the receiving entity PDCP, along with the right of blocks PDU PDCP, a special indicator that these are not in order of blocks PDU PDCP reordering require. By this special indicator receiving PDCP entity recognizes that blocks PDU PDCP [3], and PDU PDCP [5] have not been received, and temporarily stores the PDU PDCP [4], and PDU PDCP [6], which are the following not consecutive blocks PDU PDCP, in the reordering buffer, instead of the module to deliver their subsequent processing (step 535).

After performing the handover to target ENB 515, the UE 505 transmits a message to target ENB 515 of the completion of the handover (step 540). Post the completion of the handover contains information about the status of the receiving units PDU PDCP, ie serial numbers of the missing blocks PDU PDCP and the serial numbers of blocks PDU PDCP. In the above example, the message of the completion of handover comprises status information receiving units PDU PDCP, consists in the fact that they were taken blocks PDU PDCP to block PDU PDCP [6], and units PDU PDCP [3], and PDU PDCP [5] are missing.

After transmitting the handover complete UE 505 establishes a new RLC entity to be used in target ENB 515 (step 545) and waits for receipt of RLC PDU units to the new RLC receiving entity from target ENB 515.

Meanwhile, target ENB 515 receives PDCP PDU units from the source ENB 510 (step 527). Then, after receiving the message of the completion of handover from the UE 505 target ENB 515 determines the blocks PDU PDCP, to be transmitted by referring to the status information receiving units contained in the notice of completion of the handover, and then transmits the thus determined units PDU PDCP by referring to the serial numbers so determined blocks PDU PDCP (step 550). In the example, target ENB 515 transmits blocks PDU PDCP sequence PDU PDCP [3] PDU PDCP [5], PDU PDCP [7], and PDU PDCP [8] of the frame number PDU PDCP [3] PDU PDCP [4] PDCP PDU [5], PDCP PDU [6], PDCP PDU [7] and PDCP PDU [8] received from source ENB 510. At the same time, PDCP PDU [4] and PDCP PDU [6] may be removed by target ENB 515. Target ENB 515 restores blocks PDCP PDU to RLC PDU units in the above order, attaches RLC PDU units to the RLC serial numbers, and then transmits the RLC PDU units to the RLC receiving entity UE device. Since the sequence number of RLC transmitting entity, created in target ENB 515 is set to 0, target ENB 515 assigns a sequence number 0 to the first RLC PDU, the corresponding PDCP PDU [3].

Target ENB 515 and UE 505 resumes normal transmission / reception of RLC through the new transmission and receiving entities RLC (step 555), and a receiving RLC entity of the UE 505 assembles the reordered in order of the blocks PDU RLC into blocks PDU PDCP and delivers the collected blocks PDU PDCP receiving entity PDCP (step 560). During transmission / reception RLC transmission / reception of a PDU RLC block can be completely unsuccessful. This may occur, for example, in the case where the block RLC PDU is not transmitted correctly to a predetermined time interval or when retransmission has been performed maximum number of times allowed for retransmission, and no retransmission is not successful. When is the final conclusion of an unsuccessful reception of the missing PDU RLC, the receiving RLC entity performs a "delivery order" without missing unit PDU RLC. In other words, under the assumption that the missing RLC PDU unit has been received, from among the reordered in the order of RLC PDU units RLC PDU, suitable to block PDCP PDU, PDCP PDU units are collected, which are then delivered to the PDCP receiving entity.

Since the receiving RLC entity performs the above operation "delivery order", it is impossible to obtain another unit PDU PDCP sequence number with the sequence number is less than unit PDU PDCP, RLC delivered to the receiving entity, created for use in the target cell. Therefore PDCP receiving unit can determine that blocks PDCP PDU to PDCP PDU unit, delivered from the RLC transmitting entity of the target cell, followed by the order (step 565). For example, if the receiving entity PDCP received PDU PDCP [5] from the new receiving entity RLC, without adopting PDU PDCP [3], the receiving PDCP entity concludes that the PDU PDCP [3] with the serial number smaller than the sequence number PDU PDCP [5] is completely lost and that the PDCP PDU units to PDCP PDU [5] in order.

The entire operation according to the first embodiment of the present invention reduces, in essence, to the next.

- After receiving the handover command RLC receiving entity of the UE assembles all valid blocks in the RLC PDU units PDCP PDU and delivers the PDCP PDU units PDCP receiving entity. And the receiving RLC entity delivers the PDCP receiving entity, together with the PDCP PDU blocks special indication that non-consecutive blocks require PDCP PDU reordering.

- Upon receiving the PDCP PDU and special indicator PDCP receiving entity checks the sequence numbers of the received blocks and stores the PDCP PDU coming out of sequence PDCP PDU blocks, i.e. blocks PDCP PDU with sequence numbers higher than the sequence number of the missing PDCP PDU in the reordering buffer.

- The receiving PDCP entity delivers the status of the receiving units PDU PDCP entity Radio Resource Control (RRC) unit UE.

- An RRC of the UE inserts a reception status blocks PDCP PDU message in the handover complete message and then transmits a handover complete to the target ENB.

- Object RRC target ENB delivers PDU reception status blocks RLC PDCP receiving entity, created for the UE.

- Based on the reception status blocks PDCP PDU RLC transmitting entity transmits PDCP PDU blocks according to their sequence numbers, except for blocks PDCP PDU, the UE has already taken from the source ENB, from among PDCP PDU blocks, delivered from the source ENB.

- After transmission completion message Handover RLC receiving entity of the UE performs the "delivery order" RLC PDU blocks, received from the RLC receiving entity of the target ENB.

- Upon receiving the PDU PDCP from the new transmitting RLC entity receives the PDCP entity of the UE considers that the PDU PDCP among blocks PDU PDCP, are stored in the reordering buffer, to the received block of PDU PDCP follow the order and delivers the module further processing all blocks PDU PDCP sequence numbers less than the sequence number of the first missing PDU PDCP, sequence number is higher than the sequence number PDU PDCP, taken from the new transmitting entity RLC.

- PDCP receiving entity of the UE performs the reordering operation until the reordering buffer until there will be no stored PDCP PDU.

In step 605 of FIG. 6, the UE receives the command from the source ENB handover. At step 610 RLC receiving entity of the UE assembles the appropriate RLC PDU units in blocks PDCP PDU and delivers the PDCP receiving entity PDCP PDU assembled blocks together with a special indication requiring reordering PDCP PDU units.

After performing the handover to the target cell at step 615 UE transmits a handover complete to the target ENB. The UE then deletes the existing receiving object and creates a new RLC receiving entity for connection with the target cell. Then, at step 620 the newly created RLC receiving entity performs an "in order of delivery" RLC PDU blocks, received from the target cell.

As shown in FIG. 7, when at step 705 units PDU PDCP together with a special indication requiring reordering are delivered from the receiving entity RLC, the receiving PDCP entity obtains sequence numbers of correctly received blocks PDU PDCP and missing blocks PDU PDCP by checking the serial numbers of delivered units PDU PDCP and in step 707 reports received sequence number RRC entity of the UE to use the report on the status of PDCP receiving device UE. Object RRC inserts the PDCP reception status of the UE in the terminating message transmission service transmitted by a target ENB.

In step 710, the receiving PDCP entity checks the necessity PDCP PDU reordering unit, delivered from the RLC receiving entity. Based on test results PDCP receiving entity proceeds to step 720 when the reordering is necessary, and proceeds to step 715, if reordering is not necessary. If the reordering is necessary, it implies that there is at least one missing PDCP PDU.

In step 715, the receiving PDCP entity delivers the PDCP PDU blocks following block processing. Next, in step 740, the PDCP receiving entity performs normal operations for the PDCP PDU blocks, received thereafter. In other words, the PDCP receiving entity immediately delivers the PDCP PDU units from RLC receiving entity next processing block.

In step 720, the receiving PDCP entity delivers the reordered PDCP PDU blocks, i.e. blocks PDCP PDU with sequence numbers below the number of the first missing PDCP PDU, processing of the next module, and stores the remaining PDCP PDU blocks, requiring reordering in the reordering buffer. Next, in step 725, the PDCP receiving entity waits delivery unit PDCP PDU from the RLC receiving entity, the newly established for the target cell. After delivery unit PDU PDCP from the receiving entity RLC, recently established for the target cell, the receiving PDCP entity proceeds to step 730, where the receiving PDCP entity assumes that all the blocks PDU PDCP, sequence number which is higher ordinal number of the delivered PDU PDCP, to the first missing block PDCP PDU, are reaching the order of PDCP PDU blocks, and outputs the expectation-consecutive blocks PDCP PDU to a next processing block.

Thereafter, in step 735, the receiving PDCP entity checks if there are any in the reordering buffer are not running in order PDCP PDU units. Then, if in the reordering buffer are non-consecutive blocks PDCP PDU, PDCP receiving entity proceeds to step 725, at which the receiving entity continues the reordering operation. If the reordering buffer is left non-consecutive blocks PDCP PDU, PDCP receiving entity proceeds to step 740, where the PDCP receiving entity performs the normal operations.

A first embodiment of the present invention corresponds to a case in which a target ENB reorders PDCP PDU blocks, received from the source ENB and PDCP PDU blocks, received from the connection node, and then re-transmits the reordered PDCP PDU units. A second embodiment of the present invention proposes operations PDCP and RLC, when the target ENB transmits the PDCP PDU blocks without reordering them.

Preferably, at blocks PDCP PDU, which target ENB receives from a source ENB, have sequence numbers always lower sequence numbers PDCP PDU blocks, received from the connection node, and that the target ENB first transmitted PDCP PDU blocks, received from the source ENB. However, since blocks PDCP PDU delivered from the source ENB to the target ENB after passing through the anchor node, there is the possibility that they may arrive at the target ENB later than the PDCP PDU blocks, directly delivered to the target ENB from the connection node. For transmission efficiency is preferred that the target ENB stops transmitting no downlink while blocks are received PDCP PDU from the source ENB.

Therefore, the target ENB first transmits to the UE PDCP PDU first received and s the number of PDCP PDU blocks, received from the source ENB or the joining node. In this case, it is likely that the UE may receive the PDCP PDU blocks in reverse order. Furthermore, there is no possibility to receive another PDCP PDU with a sequence number below a sequence number PDCP PDU, delivered from the source ENB. However, until the moment at which no more PDCP PDU blocks, delivered from the source ENB, can still receive PDCP PDU with sequence number less than the sequence number PDCP PDU, delivered from the node connection. According to a second embodiment of the present invention, the target ENB first transmits to the UE a first incoming PDCP PDU from among PDCP PDU blocks, delivered from the source ENB or the joining node. Further, when the target ENB transmits the PDU PDCP, delivered from the source ENB, the target ENB transmits, together with a PDU PDCP indication that "since the block PDU PDCP is a block PDU PDCP, delivered from the source ENB, it is impossible that the receiving PDCP entity may receive another Unit PDU PDCP with a sequence number less than the sequence number of the PDU PDCP, and thus the receiving PDCP entity shall, upon receipt of the PDU PDCP, deliver modulo subsequent processing units PDU PDCP to the first missing block PDU PDCP with a sequence number higher than the sequence number of the PDU PDCP ". Further, for convenience of description, this figure is called the index 1. Briefly, figure 1 - is a measure for the transmission of commands PDCP receiving entity to apply the reordering operation according to the first embodiment of the present invention. Indicator 1 can be delivered as control information block RLC PDU, comprising at least part of the PDCP PDU unit.

As shown in FIG. 8, the transmitting RLC entity of the target ENB restores the PDU PDCP [n] 805 delivered from the source ENB, unit PDU RLC [m] 810 and block PDU RLC [m + 1] 815 and then transmits reconstructed PDU RLC [m] 810 and RLC PDU [m + 1] 815. In this case, the transmitting RLC entity of the target ENB attaches "control information 820, which gives the command to the indicator carriage 1 together with the current RLC PDU, when the PDCP PDU, in the current reconstructed RLC PDU, delivered PDCP receiving entity" to last PDU RLC, restore from a PDU PDCP [n] 805, that is, the PDU RLC [m + 1] 815. Further, for convenience of description, this control information 820 is called "RLC control information 1".

The receiving PDCP entity device applies the reordering operation proposed by the first embodiment of the present invention to the PDCP PDU unit, delivered together with indication 1. Thus, the receiving unit can not further PDCP PDU with sequence number less than the sequence number PDCP PDU, delivered together with indication 1. The receiving PDCP entity does not account for the possible existence of a missing unit PDU PDCP with a serial number lower than the sequence number PDU PDCP, delivered together with the index 1, and delivers module further processing all blocks PDU PDCP sequence numbers less than the sequence number of the first missing block PDU PDCP, which is higher than the ordinal block number PDU PDCP, delivered together with indication 1.

When the PDCP receiving entity received the last PDCP PDU, delivered from the source ENB to the target ENB, it is impossible to further receive PDCP PDU with sequence number less than the sequence number of the last PDCP PDU, and a further reordering operation becomes meaningless. For example, even if the PDCP PDU blocks, delivered from the node connection, stored in the buffer PDCP receiving entity due to a missing PDCP PDU, it is impossible to take the missing PDCP PDU block after the last PDCP PDU.

Therefore, according to the second embodiment of the present invention, when the target ENB transmits to the UE PDCP PDU latter, received from the source ENB, the target ENB transmits, together with the last PDCP PDU indicator 2. The indicator 2 indicates the PDCP receiving entity of the UE to deliver all coming out of order PDU is next PDCP processing module. After receiving the indicator 2 PDCP PDU with PDCP receiving entity of the UE delivers all reaching out of sequence PDCP PDU blocks, stored in the buffer, the next processing module, and then performs the normal operation. Indicator 2 may also be delivered as RLC control information of the last RLC PDU unit, comprising at least part of the PDCP PDU unit.

As shown in FIG. 8, the transmitting RLC entity restores the PDU PDCP 825 delivered from the source ENB, in units PDU RLC [k] 835 and PDU RLC [k + 1] 840 and then transmits reconstructed PDU RLC [k] 835 and PDU RLC [k + 1 ] 840. In this case, the transmitting RLC entity attaches the "control information 845, commands the delivery of index 2 along with the current PDU RLC, when PDU PDCP, rebuilt in the current PDU RLC, is delivered to the receiving entity PDCP" to the last unit PDU RLC, restored from the PDU PDCP 825, i.e. block RLC PDU [k + 1] 840. Next, for convenience of description, control information 845 is called "RLC control information 2".

As shown in FIG. 9, before receiving the handover command from source ENB 910, UE 905 in step 902 receives from the source ENB 910 units PDU RLC, corresponding PDU PDCP [1], PDU PDCP [2], PDU PDCP [4], and PDU PDCP [6] . Since the blocks PDU RLC, respective blocks PDU PDCP [1], and PDU PDCP [2] are already in sequence some of these blocks PDU RLC collected PDU PDCP [1], and PDU PDCP [2], which are then primarily delivered to the receiving PDCP entity.

When the UE 905 in step 923 receives from the source ENB 910, the handover command, UE 905 assembles all admitting assembly PDU is RLC among blocks PDU RLC, remaining in the reception buffer RLC, a PDU, PDCP, and then in step 930 delivers the collected blocks PDU PDCP receiving entity PDCP. It is assumed that the PDCP PDU [4] and PDCP PDU [6] have been correctly received and are delivered to the receiving PDCP entity. In addition, the receiving RLC entity of the UE 905 delivers PDCP receiving entity, together with the right of blocks PDU PDCP special indicator that going out of order blocks PDU PDCP reordering require. By this special indicator receiving PDCP entity recognizes that blocks PDU PDCP [3], and PDU PDCP [5] propane, and temporarily stores blocks PDU PDCP [4], and PDU PDCP [6], which are non-consecutive PDU PDCP, in reordering buffer, instead of the module to deliver their subsequent processing at step 935.

After performing the handover to target ENB 915 in step 905 UE 940 to the target ENB 915 transmits a completion message to the handoff. Post the completion of the handover contains information about the status of the receiving units PDCP, ie serial numbers of the missing blocks PDU PDCP and the serial numbers of blocks PDU PDCP. In the above example, the message of the completion of the handover status information comprises receiving PDCP PDU blocks, blocks that PDCP PDU to PDCP PDU block [6] have been received while PDCP PDU blocks [3] and PDCP PDU [5] are missing.

After transmitting the handover complete UE 905 at step 915 establishes a new RLC entity, which is used in target ENB 915 and awaits receipt of RLC PDU units to the new RLC receiving from the target ENB 915.

Meanwhile, target ENB 915 receives PDCP PDU units from the source ENB 910 and the connection node. In this case, the description is based on a case where blocks PDCP PDU received from a node before joining. In other words, in step 929 blocks PDCP PDU, since the block PDCP PDU [9] start to be received from the connection node, and blocks PDCP PDU [3] on the PDCP PDU [8] are received at step 927 from the source ENB 910. The transmitting entity RLC, newly created in the target ENB 915 stores the received PDCP PDU units in the transmission buffer in the order in which they were taken. Namely, they are stored in the transmission buffer in the order of PDU PDCP [9], PDU PDCP [10], PDU PDCP [11], PDU PDCP [3], PDU PDCP [5], PDU PDCP [6], PDU PDCP [7] , PDCP PDU [8], PDCP PDU [12], etc.

Then, after receiving the message of the completion of handover from the UE 905 target ENB 915 determines to be transmitted PDU, PDCP, referring to the status information receiving units PDU PDCP, provided in the communication handover complete, then at step 950 transmits thus determined by the PDU PDCP, referring to the sequence numbers thus determined blocks PDU PDCP. In the example of the number of blocks PDU PDCP [3] on the PDU PDCP [8] received from source ENB 910, only blocks PDU PDCP [3] PDU PDCP [5], PDU PDCP [7], and PDU PDCP [8] transmitted to the UE 905. In addition, PDCP PDU blocks are transmitted in the order in which they are stored in the transmission buffer, i.e. in the order of PDCP PDU [9], PDCP PDU [10], PDCP PDU [11], PDCP PDU [3] , PDCP PDU [5], PDCP PDU [6], PDCP PDU [7], PDCP PDU [8] and PDCP PDU [12]. Since the sequence number of RLC transmitting entity, created in target ENB 915 is set to 0, target ENB 915 provides a sequence number 0 to the first RLC PDU unit, the respective block PDCP PDU [3].

UE 905 performs the operation in step 955 "in order of delivery" operation according to the reception of a new RLC receiving entity RLC, collects-consecutive blocks in RLC PDU units PDCP PDU and then delivers in step 960 the collected PDCP PDU units to the receiving entity. Thus, the block PDU PDCP, created by collecting units PDU RLC, containing control information RLC 1 is delivered together with indication 1 to the receiving entity PDCP, and the unit PDU PDCP, created by collecting units PDU RLC, containing control information RLC 2 is delivered together with indication 2 receiving entity PDCP.

Upon receiving the PDCP PDU from the RLC receiving entity, the newly created in the target cell, the receiving PDCP entity checks whether a received PDU is accompanied by indication 1 or PDCP indication 2. When the received PDCP PDU is accompanied by indication 1, the receiving PDCP unit assumes PDCP PDU units that follow order previously received PDCP PDU, and delivers in step 965 blocks further processing module PDCP PDU before a first missing PDCP PDU block with a sequence number higher than the sequence number received PDCP PDU. If, however, block the received PDCP PDU is accompanied by indication 2, PDCP receiving entity assumes all PDCP PDU received blocks, stored in the buffer including the received PDCP PDU, followed in order, at step 970, and delivers them to the next processing module.

In step 1005 of FIG. 10 The UE receives a handover command from the source ENB. In step 1010, the receiving RLC entity of the UE assembles the appropriate RLC PDU units in blocks PDCP PDU and delivers the PDCP receiving entity PDCP PDU assembled blocks together with a special indication requiring reordering PDCP PDU units.

After performing the handover to the target cell at step 1015, the UE transmits the message to the target ENB handover complete. The UE removes the existing RLC receiving entity and creates a new RLC receiving entity for connection with the target cell. Next, in step 1020, the newly constructed RLC receiving entity performs the "delivery order" RLC PDU blocks, received from the target cell. In step 1025, the newly constructed RLC receiving entity delivers PDU-consecutive PDCP receiving entity PDCP. Thus, the block PDU PDCP, created by collecting units PDU RLC, containing control information RLC 1 is delivered together with indication 1 to the receiving entity PDCP, and the unit PDU PDCP, created by collecting units PDU RLC, containing control information RLC 2 is delivered together with indication 2 receiving entity PDCP.

As shown in FIG. 11, when the blocks PDU PDCP together with a special indication requiring reordering are delivered in step 1105 from the receiving entity RLC, the receiving PDCP entity obtains sequence numbers of correctly received blocks PDU PDCP and missing blocks PDU PDCP by checking the serial numbers of delivered units PDU PDCP and in step 1107 reports received sequence numbers RRC entity of the UE to use the report on the status of PDCP receiving device UE. Object RRC inserts the PDCP reception status of the UE in the terminating message transmission service transmitted by a target ENB.

In step 1110, the receiving PDCP entity checks the necessity PDCP PDU reordering unit, delivered from the RLC receiving entity. Depending on the result of PDCP receiving entity proceeds to step 1120, if desired, reordering, or proceeds to step 1115 when the reordering is required. If rescheduling is required, that means that there is at least one missing PDCP PDU.

In step 1115, the receiving PDCP entity delivers the received PDCP PDU blocks next processing module. Then, in step 1140, the receiving PDCP entity performs normal operations for blocks PDU PDCP, adopted after them. In other words, the PDCP receiving entity immediately delivers the PDCP PDU blocks next processing module, once it receives the PDCP PDU units from RLC receiving entity.

At step 1120, the PDCP receiving entity delivers the reordered PDCP PDU blocks, i.e. blocks PDCP PDU with sequence number less than the sequence number of the first missing PDCP PDU, processing of the next module, and stores the remaining PDCP PDU blocks, requiring reordering in the reordering buffer. Next, in step 1125, the receiving PDCP entity awaits delivery unit PDCP PDU from the RLC receiving entity, the newly established for the target cell. When sending unit PDCP PDU from RLC receiving entity, for the newly established target cell PDCP receiving entity proceeds to step 1127 at which the PDCP receiving entity determines whether the PDU is accompanied by indication 2. The PDCP receiving PDCP entity proceeds to step 1128, where the PDU PDCP is accompanied by indication 2, and proceeds to step 1129 when the PDCP PDU unit is not accompanied by indication 2.

As figure 2 indicates the impossibility of subsequent reception of another PDU PDCP with a sequence number less than the sequence number of the delivered PDU PDCP and the inability to reorder any blocks PDU PDCP, are stored in the reordering buffer, so that they were in order, the receiving PDCP entity delivers all the PDU PDCP, is stored in the reordering buffer, the next processing module, and then proceeds to step 1140 at which the PDCP receiving entity performs the normal operations.

If the block PDCP PDU is not accompanied by indication 2, PDCP receiving entity proceeds to step 1129 at which the PDCP receiving entity determines whether the block PDU is accompanied by indication 1. Since PDCP figure 1 indicates the impossibility of subsequent receipt of another block PDCP PDU with sequence number less than the sequence number delivered PDU PDCP, the receiving PDCP entity proceeds to step 1130 at which the receiving PDCP entity assumes that all the blocks PDU PDCP sequence numbers higher than the sequence number of the delivered unit PDU PDCP to the first missing block PDU PDCP are-consecutive blocks PDU PDCP, and outputs expectation-consecutive blocks of the next PDCP PDU processing module.

Thereafter, in step 1135 the receiving PDCP entity checks whether there are any non-consecutive blocks in a PDCP PDU reordering buffer. Then, if the running units out of sequence PDCP PDU left in the reordering buffer, receiving entity proceeds to step 1125 at which the receiving PDCP entity continues to perform the reordering operation. If non-consecutive blocks PDCP PDU is not left in the reordering buffer PDCP receiving entity proceeds to step 1140 at which the PDCP receiving entity performs the normal operations.

Meanwhile, if the result of the determination in step 1129 concludes that the PDCP PDU unit is not accompanied by indication 1, PDCP receiving entity proceeds to step 1133, where the PDCP receiving entity stores the PDCP PDU block in the reordering buffer according to its sequence number. Then the PDCP receiving entity proceeds to step 1125 in which PDCP receiving entity performs the normal operations.

As shown in FIG. 12, the transmitting RLC entity 1270 target ENB includes a transmission buffer 1215, adding module 1220 segmentation / header buffer 1225, and reordering control unit 1230 RLC. Transmission buffer 1215 stores PDCP PDU blocks 1205 delivered from the source ENB, and blocks 1210 PDCP PDU delivered from the connection node. According to a first embodiment of the present invention, transmission buffer 1215 stores the delivered PDCP PDU blocks after ordering them according to their sequence numbers. According to a second embodiment of the present invention, transmission buffer 1215 stores the delivered PDCP PDU units according to the order in which these blocks were delivered PDCP PDU.

Transmission buffer 1215 delivers the PDCP PDU blocks, said RLC control unit 1230, from among the stored PDCP PDU blocks add segmentation module 1220 / header 1220 and removes the delivered PDCP PDU units.

1220 adding module segmentation / header segments 1220 and connects the blocks PDCP PDU, delivered from transmission buffer 1215, in PDCP PDU units, each of which has a proper size, and then inserts the RLC header, which includes the RLC sequence number, etc. in PDCP PDU units, thereby restoring at least one RLC PDU. Thus, if the module 1230 controls RLC control information has been transmitted RLC, adding module 1220 segmentation / header inserts the RLC control information into a predetermined location of the restored block RLC PDU. Block RLC PDU arrives at the retransmission buffer 1225 and a lower level. Block RLC PDU, ringing on a lower level, is supplied to the RLC receiving entity 1275 of the UE according to a predetermined sequence, and the RLC PDU unit, received by the retransmission buffer 1225 is stored until receipt of the ACK signal from RLC receiving entity 1275.

RLC control unit 1230 controls transmission and retransmission of RLC PDU units or blocks PDCP PDU, stored in the transmission buffer 1215 and retransmission buffer 1225. Specifically, RLC control unit 1230 receives an object from the RRC (not shown) of the serial numbers of blocks PDCP PDU, which the UE correctly received from the source ENB, and removes the PDCP PDU units from the buffer 1215 transmission. Furthermore, if there is RLC control information, to be transmitted device UE, RLC control unit 1230 delivers the RLC control information adding module 1220 segmentation / header so that the RLC control information can be transmitted to the hitch unit RLC PDU. According to a second embodiment of the present invention, when the unit PDU PDCP, delivered from the buffer 1215 transmission is a block PDU PDCP, delivered from the source ENB, module 1230 controls RLC controls the 1220 addition of the segmentation / header so that the corresponding block PDU RLC been attached control Information 1 RLC. During transmission of the last PDCP PDU unit, delivered from the source ENB, RLC control unit 1230 controls segmentation module 1220 add / header so that RLC control information 2 was attached to a corresponding RLC PDU unit.

RLC receiving entity 1275 includes a reception buffer 1235, control module 1245 and module 1240 RLC reassembly. Buffer 1235 stores a reception RLC PDU blocks, received from the ENB, according to RLC sequence numbers. Blocks from among RLC PDU-consecutive RLC PDU, which can be assembled into PDCP PDU blocks, are delivered from reception buffer 1235 to reassembly unit 1240. Moreover, if the RLC PDU includes control information, the control information is delivered to RLC control unit 1245.

Reassembly module 1240 assembles RLC PDU units, delivered from reception buffer 1235 into blocks PDCP PDU and then delivers the PDCP PDU units PDCP receiving entity 1280.

When the UE receives a handover command module 1245 controls RLC manages buffer 1235 receiving so that the buffer 1235 receiving delivers module 1240 reassembling all blocks PDU RLC, suitable for assembly as a unit PDU PDCP, of the number of blocks PDU RLC, stored in the buffer 1235 reception. Furthermore, the module 1245 RLC control delivers a specific indicator module 1265 controls reordering from the receiving PDCP entity 1280 to request stored in the buffer 1250 reordering units PDU PDCP, delivered at the appropriate time (i.e. the time at which delivered a specific indicator) until they will not be located in order. Meanwhile, if the handover of the UE is completed, the object RRC 1260 collects information about the status of reception of blocks PDU PDCP reordering control unit 1265 and inserts the collected information on the status of the reception block in message PDU PDCP handover complete by the target ENB.

According to the second embodiment, if the receiving RLC entity 1275 receives from the target ENB control information RLC 1 with the unit PDU RLC, module 1245 RLC control delivers figure 2 module 1265 controls reordering receiving PDCP entity 1280 together with the block of PDU PDCP, assembled from units PDU RLC, containing RLC control information 2.

The receiving PDCP entity 1280 includes a reordering buffer 1250, 1265 control unit and reordering processing of the next module in 1255. Module 1255 processing can include, for example, the module and the decryption module for decompressing the header processing higher-level protocol in connection with the service provided by the device UE.

Usually, the reordering buffer 1250 directly delivers a PDCP PDU unit, delivered from RLC receiving entity 1275 to the following processing module 1255. However, when it receives a command to the reordering of the reordering control unit 1265, reordering buffer 1250 stores the blocks PDU PDCP, you want to reorder.

According to a first embodiment of the present invention, when the buffer 1250 reordering takes block PDU PDCP of the newly created receiving RLC entity 1275 and thus blocks PDU PDCP, requiring reordering are stored in the buffer 1250 reordering buffer 1250 reorder consider that blocks PDU PDCP to the first missing PDCP PDU block with a sequence number higher than sequence numbers of the received PDCP PDU are arranged in order, and delivers the PDCP PDU blocks next module 1255 processing. Then, when there is no stored PDU PDCP reordering buffer 1250 performs normal operations again and directly delivers received blocks PDU PDCP next module 1255 processing.

According to a second embodiment of the present invention, when the buffer 1250 reordering takes block PDU PDCP together with indicator 1, the buffer 1250 reorder consider that blocks PDU PDCP to the first missing block PDU PDCP with a sequence number higher than the sequence number received PDU PDCP arranged in order, and directly It delivers PDCP PDU blocks next module 1255 processing. Further, when reordering buffer 1250 assumes PDCP PDU block with index 2, reordering buffer 1250 considers that all stored PDCP PDU units are arranged in sequence and delivers all the PDCP PDU next module 1255 processing.

Subsequent processing module 1255 recovers IP-packet by decoding units PDU PDCP, delivered from the reordering buffer 1250, and restore the header and then delivers the IP-packet to a higher level (for example, IP-level).

Hereinafter briefly describe the results provided by the present invention which is constructed and operates as described above.

According to the present invention, when handover of recovery object ARQ in a mobile communication system entity PDCP, which is the object ARQ higher level, performs the reordering such that the target cell can implement selective retransmission packets to the UE, the UE has not received in a source cell . Therefore, the present invention can improve communication efficiency.

Although this has been shown and described with reference to certain exemplary embodiments thereof, those skilled in the art will appreciate that it may be made various changes in form and particulars without departing from the spirit and scope of the invention as defined by the appended claims .