WO2015165418A1 - Pdcp发送实体、辅基站、用户设备及其方法 - Google Patents

Pdcp发送实体、辅基站、用户设备及其方法 Download PDF

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Publication number
WO2015165418A1
WO2015165418A1 PCT/CN2015/077948 CN2015077948W WO2015165418A1 WO 2015165418 A1 WO2015165418 A1 WO 2015165418A1 CN 2015077948 W CN2015077948 W CN 2015077948W WO 2015165418 A1 WO2015165418 A1 WO 2015165418A1
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Prior art keywords
pdcp
pdcp pdu
sequence number
timer
window
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PCT/CN2015/077948
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English (en)
French (fr)
Inventor
肖芳英
刘仁茂
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夏普株式会社
肖芳英
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Application filed by 夏普株式会社, 肖芳英 filed Critical 夏普株式会社
Priority to US15/307,661 priority Critical patent/US20170055176A1/en
Publication of WO2015165418A1 publication Critical patent/WO2015165418A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/0268—Traffic management, e.g. flow control or congestion control using specific QoS parameters for wireless networks, e.g. QoS class identifier [QCI] or guaranteed bit rate [GBR]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/28—Timers or timing mechanisms used in protocols
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
    • H04L5/0055—Physical resource allocation for ACK/NACK
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
    • H04L43/0823—Errors, e.g. transmission errors
    • H04L43/0829—Packet loss

Definitions

  • the present disclosure relates to mobile communications, and in particular, to a packet data convergence protocol PDCP transmitting entity, a secondary base station, a PDCP receiving entity, a method of transmitting a Packet Data Convergence Protocol Data Unit (PDCP PDU) at a PDCP transmitting entity, and a secondary base station to a primary base station A method of reporting successful PDCP PDU transmission and a method for the PDCP receiving entity to confirm successful reception of the PDCP PDU, so that the transmission window of the PDCP transmitting entity moves synchronously with the receiving window of the PDCP receiving entity.
  • PDCP PDU Packet Data Convergence Protocol Data Unit
  • the layer 2 (User-Plane Protocol Stack) of the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) system consists of 3 sub-layers, from high to low: packet data convergence protocol ( Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, and Media Access Control layer.
  • the transmitting entity receives a Service Data Unit (SDU) from a higher layer, provides a service for the layer, and outputs a Protocol Data Unit (PDU) to the lower layer.
  • SDU Service Data Unit
  • the RLC layer receives packets from the PDCP. These packets are PDCP PDUs for the PDCP layer but RLC SDUs for the RLC layer.
  • the PDCP entity used to transmit the PDCP PDU is called PDCP Tx
  • the RLC entity used to transmit the RLC PDU is called RLC Tx.
  • the process is reversed, with each layer sending an SDU to the upper layer and the upper layer receiving it as a PDU.
  • the PDCP entity for receiving the PDCP PDU is called PDCP Rx
  • the RLC entity for receiving the RLC PDU is called RLC Rx.
  • the PDCP SDU is identified by a PDCP sequence number (SN)
  • the PDCP SDU has the same sequence number as the corresponding PDCP PDU and the RLC SDU
  • the RLC PDU is identified by the RLC sequence number.
  • the PDCP sequence number and the RLC sequence number can be recycled.
  • the new PDCP SDU is numbered again from the minimum value, but the corresponding superframe number is incremented by 1.
  • a COUNT consisting of a PDCP sequence number and a Hyper Frame Number (HFN) uniquely identifies a PDCP SDU.
  • each radio bearer has a PDCP entity (entity) And an RLC entity.
  • Each base station also known as a NodeB or evolved NodeB (eNB)
  • each user equipment has one MAC entity.
  • the user equipment may be a user terminal, a user node, a mobile terminal, or a tablet.
  • the 3GPP LTE Release 12 standard under development includes standardization work for user equipments having dual connectivity capabilities, a primary base station (Master eNB, MeNB), and a secondary base station (Secondary eNB, SeNB).
  • the primary base station is responsible for maintaining the Radio Resource Management (RRM) measurement configuration of the user equipment and requesting the secondary base station to provide additional equipment for the user equipment based on the received measurement report or traffic conditions or bear type. Resources.
  • RRM Radio Resource Management
  • the secondary base station After receiving the request from the primary base station, the secondary base station configures the serving cell for the user equipment or rejects the request due to insufficient resources.
  • the option 3C shown in FIG. 1 has the following features: (1) a primary base station (also referred to as a MeNB) communicates with a Serving Gateway (S-GW) through an S1-U interface; and (2) carries a primary base station. (3) For a split bearer, there is a corresponding RLC entity in the primary base station and the secondary base station (Secondary eNB, also called SeNB).
  • a primary base station also referred to as a MeNB
  • S-GW Serving Gateway
  • SeNB secondary base station
  • the RLC entity located at the secondary base station interacts with the upper layer (ie, the PDCP entity located at the primary base station) through an Xn interface, which includes the X2 interface.
  • the dual-connected user equipment configures one PDCP entity and two RLC entities for the split bearer, where the PDCP entity corresponds to the PDCP entity in the MeNB, and one of the two RLC entities and the MeNB The RLC entity corresponds to another RLC entity corresponding to the RLC entity in the SeNB.
  • each PDCP Rx corresponds to only one RLC Rx.
  • the reordering function of the RLC receiving entity ensures that the PDCP Rx receives the PDCP PDUs in order from the RLC layer.
  • one PDCP Rx corresponds to two RLC Rx, and the PDCP PDU received by the PDCP Rx from the two RLC Rx is out of order. Therefore, PDCPRx needs to reorder the PDCP PDUs from the two RLC Rx.
  • the PDCP reordering function will be based on a similar base of UM RLC.
  • the reordering method for the t-Reordering timer This rearrangement method is disclosed in 3GPP TR 36.300, which is incorporated herein in its entirety by reference.
  • the main idea of the method is that the PDCP Rx maintains a receiving window, also called a reordering window, which is half the size of the PDCP PDU sequence number space.
  • the PDCP Rx receives the PDCP PDU from the two RLC Rx and discards the received PDCP PDU whose sequence number is not in the receive window.
  • the PDCP PDU When receiving a PDCP PDU that does not arrive in order but the sequence number falls within the receive window, the PDCP PDU is stored in a reordering buffer and a t-Reordering timer is started, waiting for the missing PDCP PDU to arrive.
  • the PDCP SDUs that have been received in order are delivered to the upper layer; or when the t-Reordering timer expires, the corresponding t-Reordering timers are not sequentially arrived.
  • Other PDCP SDUs that have arrived in sequence outside the PDCP SDU are submitted to the upper layer.
  • the lower bound of the receiving window is set to the maximum sequence number of the PDCP SDU that has been submitted to the upper layer plus one.
  • the RLC Tx located in the SeNB shall send an indication message that the PDCP PDU is successfully sent to the PDCP Tx located in the MeNB through the Xn interface, so that the PDCP Tx can send more PDCP PDUs.
  • the data may be lost.
  • the RLC Tx located at the SeNB cannot send an acknowledgment message to the PDCP Tx because the data is not received, which will cause the PDCP Tx to transmit the lost PDCP PDU and the subsequent transmittable PDCP PDU whose sequence number is greater than the lost PDCP PDU.
  • the serial number is smaller than the serial number of the lost PDCP PDU plus the value of half of the serial number space, the new PDCP PDU cannot be sent, which affects the transmission delay and reliability of the wireless link.
  • the present invention aims to provide a mechanism for a PDCP transmitting entity to move a transmission window after a packet loss occurs on the Xn interface, and then continue to transmit. Continued PDCP PDU.
  • a method for transmitting a Packet Data Convergence Protocol Data Unit (PDCP PDU) at a Packet Data Convergence Protocol (PDCP) transmitting entity comprising: upon receiving an indication message that a PDCP PDU is successfully transmitted Transmitting the transmission window according to the sequence number of the successfully transmitted PDCP PDU indicated in the indication message, such that the lower bound of the transmission window indicates the minimum sequence number of the PDCP PDU that was not confirmed to be successfully transmitted.
  • the method also includes determining whether there is a PDCP PDU whose sequence number is greater than the lower bound of the transmit window that was confirmed to have been successfully transmitted. If it does, start the timer.
  • the transmit window is moved when the timer expires.
  • the lower bound of the transmit window is set to a minor sequence number of a PDCP PDU that has not been acknowledged to be successfully transmitted; and a determination is made as to whether a acknowledgement has been successfully sent.
  • the PDCP PDU whose sequence number is greater than the lower bound of the transmission window. If present, the timer is started.
  • the running timer is deleted.
  • the timer before starting the timer, it is determined whether a PDCP PDU corresponding to a lower boundary of the transmission window is sent to the secondary base station. If yes, the timer is started; otherwise, the timer is not operated.
  • a method for transmitting a Packet Data Convergence Protocol Data Unit (PDCP PDU) at a Packet Data Convergence Protocol (PDCP) transmitting entity comprising: receiving a receiving end indication message from a PDCP receiving entity, The receiving end indication message indicates a minimum sequence number of a PDCP PDU that is not received by the PDCP receiving entity; comparing a lower boundary of the sending window with a sequence number of a PDCP PDU indicated by the receiving end indication message; if the sending If the lower bound of the window is less than or equal to the sequence number of the PDCP PDU indicated by the receiving end indication message, the lower boundary of the sending window is moved to a PDCP that is greater than the serial number carried in the receiving end indication message and has not been confirmed. The smallest serial number in the serial number of the PDU.
  • a method for successfully receiving a acknowledgment packet data convergence protocol protocol data unit (PDCP PDU) at a packet data convergence protocol (PDCP) receiving entity comprising: maintaining a receiving window, The lower bound of the receive window indicates the minimum sequence number of the PDCP PDU that has not been received; when the received sequence number is greater than the lower bound of the receive window, the sequence When the column number falls into the PDCP PDU in the receiving window, the timer is started; when the PDCP PDU corresponding to the lower window of the receiving window is received, the receiving window is moved and the timer is deleted; when the timer expires, the mobile station moves Receiving the window, and sending an indication message to the primary base station that sends the PDCP PDU to instruct the primary base station to move the transmission window, where the message includes the minimum sequence number of the PDCP PDU that has not been received.
  • PDCP PDU acknowledgment packet data convergence protocol protocol data unit
  • the lower bound of the receive window is set to the second smallest sequence number of the PDCP PDU that has not been received.
  • a method for successfully transmitting a acknowledgment packet data convergence protocol protocol data unit (PDCP PDU) at a secondary base station comprising: receiving a PDCP PDU to be transmitted from a primary base station, each PDCP PDU being Having a sequence number; and after successfully transmitting at least one PDCP PDU, transmitting a message to the primary base station indicating that the PDCP PDU was successfully transmitted, the message indicating the sequence number of the successfully transmitted PDCP PDU.
  • PDCP PDU acknowledgment packet data convergence protocol protocol data unit
  • a packet data convergence protocol PDCP transmitting entity including: a timer; a receiver configured to receive an indication message that a Packet Data Convergence Protocol Data Unit (PDCP PDU) is successfully transmitted; a window moving unit configured to move a transmission window according to a sequence number of the successfully transmitted PDCP PDU indicated in the indication message; and a timer controller configured to determine whether there is a serial number greater than the number that is confirmed to have been successfully transmitted.
  • PDCP PDU of the lower boundary of the transmission window is described, and the timer is started when it is determined that there is a PDCP PDU whose sequence number is greater than the lower boundary of the transmission window.
  • a packet data convergence protocol PDCP transmitting entity comprising: a receiver configured to receive a receiving end indication message from a PDCP receiving entity, the receiving end indication message indicating the PDCP receiving entity a minimum sequence number of the unreceived Packet Data Convergence Protocol Data Unit (PDCP PDU); and a transmission window mobile unit configured to compare a lower boundary of the transmission window maintained by the PDCP transmitting entity with the receiving end indication message a sequence number of the indicated PDCP PDU; if the lower boundary of the transmission window is less than or equal to a sequence number of the PDCP PDU indicated by the receiving end indication message, moving a lower bound of the transmission window to be greater than the receiving end indication message The smallest serial number in the serial number of the PDCP PDU that is carried in the serial number and has not been confirmed.
  • PDCP PDU Packet Data Convergence Protocol Data Unit
  • a user equipment comprising: a memory configured to maintain a receiving window, a lower bound of the receiving window indicating packet data that has not been received a minimum sequence number of a convergence protocol protocol data unit (PDCP PDU); a receiver configured to receive at least one PDCP PDU; a timer; a timer controller configured to receive a sequence number greater than the reception when the receiver receives When the lower boundary of the window but the sequence number falls into the PDCP PDU in the receiving window, the timer is started, and when the receiver receives the PDCP PDU corresponding to the lower window of the receiving window, the timer is deleted; the receiving window moving unit, And configured to: when the receiver receives a PDCP PDU corresponding to a lower bound of the receiving window or when the timer expires, move the receiving window; and the transmitter is configured to, when the timer expires, The primary base station from which the received PDCP PDU is sent sends an indication message to indicate that the primary base
  • a secondary base station that cooperates with a primary base station, comprising: a receiver configured to receive, from a primary base station, a Packet Data Convergence Protocol Data Unit (PDCP PDU) to be transmitted, each PDCP The PDUs each have a sequence number; the transmitter is configured to, after successfully transmitting the at least one PDCP PDU, send a message to the primary base station indicating that the PDCP PDU was successfully transmitted, the message indicating the sequence number of the successfully transmitted PDCP PDU.
  • PDCP PDU Packet Data Convergence Protocol Data Unit
  • the transmission window can still be moved, that is, the PDCP Tx can still send new data without affecting the wireless. Link transmission delay and reliability.
  • the PDCP sending entity moves the transmission window by maintaining a receiving window by the DCP receiving entity and by using a t-Reordering timer, so that the transmission window can be moved even if packet loss occurs on the Xn interface, Moreover, the superframe number synchronization of the PDCP transmitting entity and the PDCP receiving entity is maintained.
  • Figure 1 is a schematic diagram of the dual connectivity deployment option 3C given in 3GPP TR 36.842.
  • FIG. 2 shows a flow diagram of a method of transmitting a PDCP PDU at a PDCP transmitting entity, in accordance with one or more embodiments of the present disclosure.
  • FIG. 3 is another flow diagram illustrating a method of transmitting a PDCP PDU at another PDCP transmitting entity, in accordance with one or more embodiments of the present disclosure.
  • FIG. 4 is a flow chart illustrating a method of operating a t-Transmitting timer, in accordance with one or more embodiments of the present disclosure.
  • FIG. 5 is another flow diagram illustrating a method of transmitting a PDCP PDU at another PDCP transmitting entity, in accordance with one or more embodiments of the present disclosure.
  • FIG. 6 is a flow diagram showing a method of transmitting a PDCP PDU at yet another PDCP transmitting entity, in accordance with one or more embodiments of the present disclosure.
  • FIG. 7 is a flowchart of a method for a secondary base station SeNB to send an indication message indicating that a PDCP PDU is successfully transmitted to a primary base station MeNB, according to one or more embodiments of the present disclosure.
  • FIG. 8 is a diagram showing an example of a bitmap.
  • FIG. 9 is a flowchart of a method in which a secondary base station SeNB transmits an indication message indicating that a PDCP PDU is successfully transmitted to a primary base station MeNB, according to one or more embodiments of the present disclosure.
  • FIG. 10 is a flowchart illustrating a method of confirming receipt of a PDCP PDU at a PDCP receiving entity, in accordance with one or more embodiments of the present disclosure.
  • FIG. 11 is another flow diagram illustrating a method of transmitting a PDCP PDU at another PDCP transmitting entity, in accordance with one or more embodiments of the present disclosure.
  • FIG. 12 is a schematic structural block diagram showing a PDCP transmitting entity of one or more embodiments of the present disclosure.
  • FIG. 13 is a schematic block diagram showing a schematic configuration of a secondary base station of one or more embodiments of the present disclosure.
  • FIG. 14 is a block diagram showing a schematic configuration of a user equipment of one or more embodiments of the present disclosure.
  • FIG. 15 is a schematic block diagram showing a PDCP transmitting entity according to one or more embodiments of the present disclosure.
  • FIG. 2 is a flow diagram showing a method 200 of transmitting a PDCP PDU at a PDCP transmitting entity, in accordance with one or more embodiments of the present disclosure.
  • a current PDCP PDU transmission space using a method similar to the transmit window employed by the RLC entity.
  • the present invention is not limited to the description of the transmission window to describe the currently transmittable PDCP PDU.
  • the method described in FIG. 2 maintains a transmitting window in the PDCP transmitting entity, and the lower bound of the transmitting window corresponds to the minimum sequence number of the PDCP PDU that has not been confirmed to be successfully transmitted.
  • the currently transmittable PDCP PDU is defined by the lower and upper bounds of the transmit window.
  • the lower bound of the transmit window is the smallest sequence number of the transmittable PDCP PDU; the upper bound of the transmit window is the maximum sequence number of the transmittable PDCP PDU +1.
  • the size of the send window is half the space of the PDCP PDU sequence number.
  • the PDCP Tx can only send PDCP PDUs with sequence numbers in the transmit window.
  • the transmission of the transmission window relies on receiving an acknowledgment message that has been successfully transmitted from two RLC entities located at the MeNB and the SeNB, respectively.
  • the comparison of the serial numbers referred to herein and other parts of the present disclosure refers to the comparison of the COUNT values corresponding to the serial numbers, and the addition and subtraction calculation of the serial numbers involved also refers to the COUNT values corresponding to the serial numbers. Addition and subtraction calculations.
  • the PDCP transmitting entity receives an indication message that the PDCP PDU is successfully transmitted.
  • the PDCP transmitting entity moves its transmission window according to the indication message such that the lower bound of the transmission window indicates the minimum sequence number of the PDCP PDU that was not acknowledged to be successfully transmitted.
  • step S220 it is determined whether there is a PDCP PDU whose sequence number is greater than the lower bound of the transmission window that has been confirmed to be successfully transmitted.
  • step S220 If it is determined at step S220 that there is a PDCP PDU whose sequence number is greater than the lower bound of the transmission window, the timer is started, and at step S230, the timer is started. Otherwise, at step S240, if the timer is running, the timer is deleted.
  • a timer is introduced to start a timer when packet loss may occur.
  • an appropriate operation is performed when the timer expires, so that the transmission window can still be moved when packet loss occurs.
  • FIG. 3 is a diagram showing another PDCP transmitting entity in accordance with one or more embodiments of the present disclosure. Another flow diagram of a method 300 of transmitting a PDCP PDU.
  • t-Transmittingtimer is the value of the t-Transmitting timer.
  • the value of the t-Transmitting timer of the PDCP transmitting entity depends on the value of the t-Reordering timer at the corresponding PDCP receiving entity.
  • the t-Transmitting timer can be set to the same value as the t-Reordering timer or slightly smaller than the value of the t-Reordering timer.
  • the comparison of the serial number sizes refers to the comparison of the COUNT values corresponding to the serial numbers.
  • step S310 the PDCP sending entity receives an indication message that the PDCP PDU is successfully transmitted from the lower layer entity and moves the transmission window according to the indication message. If the indication message indicates that the PDCP SDU corresponding to the lower boundary of the current transmission window has been successfully transmitted, the PDCP transmitting entity updates the lower boundary of the transmission window to a new minimum sequence number of the PDCP PDU that has not been confirmed to be successfully transmitted.
  • step S320 the PDCP transmitting entity determines whether there is a PDCP PDU whose sequence number is greater than the lower bound of the transmission window that has been confirmed to be successfully transmitted. If yes, step S330 is performed; otherwise, step S360 is performed.
  • step S330 the PDCP transmitting entity performs a corresponding operation according to whether the lower bound of the transmission window is updated in step S310. If the lower bound of the transmission window has been updated, step S350 is performed; otherwise, step S340 is performed.
  • step S340 the PDCP transmitting entity determines whether there is a running t-Transmitting timer. If not, step S350 is performed.
  • step S350 the PDCP sending entity starts or restarts the t-Transmitting timer, that is, if the t-Transmitting timer is running, the t-Transmitting timer is restarted, otherwise, the t-Transmitting timer is started.
  • step S360 the PDCP sending entity determines whether the t-Transmitting timer is running, and if so, deletes the running timer.
  • a timer is introduced to start a timer corresponding to the packet when packet loss may occur.
  • an appropriate operation is performed when the timer expires, so that the transmission window can still be moved when packet loss occurs.
  • FIG. 4 is a diagram showing operation t-Transmitting in accordance with one or more embodiments of the present disclosure. Flowchart of method 400 of the timer.
  • step S410 After the method starts, it is confirmed at step S410 whether the t-Transmitting timer expires.
  • the lower threshold of the transmission window is set to the minor sequence number of the PDCP PDU that has not been acknowledged to be successfully transmitted, that is, except for the PDCP PDU corresponding to the t-Transmitting timer.
  • step S430 the sequence number of the PDCP PDU corresponding to the maximum sequence number of the successfully transmitted PDCP PDU and the lower threshold of the transmission window is compared.
  • step S440 the t-Transmitting timer is restarted again. Otherwise, the t-Transmitting timer is no longer set. The method ends.
  • the lower bound of the transmission window is set to the minimum sequence number of the PDCP PDU that has not been confirmed to be successfully transmitted except the PDCP PDU corresponding to the t-Transmitting timer. .
  • the t-Transmitting timer is started again. According to this embodiment, even if packet loss may occur, the transmission window is moved when the timer expires. Therefore, it is possible to avoid a situation in which the transmission window is stagnant due to packet loss.
  • the dual link deployment mode in LTE Release 12 is only applicable to the RLC Acknowledge Mode.
  • the RLC entity located at the MeNB can always ensure that all PDCP PDUs from the upper layer are correctly transmitted. Therefore, in order to avoid frequent start of the t-transmitting timer, the PDCP transmitting entity may start the t-transmitting timer only for the PDCP PDU sent by the SeNB, that is, if the PDCP PDU with the smallest sequence number that has not been confirmed (the lower window of the transmission window) is The t-Transmitting timer is started by the SeNB and the PDCP PDU sequence number is smaller than the maximum sequence number of the successfully transmitted PDCP PDU.
  • FIG. 5 is another flow diagram illustrating a method 500 of transmitting a PDCP PDU at another PDCP transmitting entity, in accordance with one or more embodiments of the present disclosure.
  • Steps S510, S520, S530, and S540 are the same as steps S310, S320, S330, and S340 in the method 300 shown in FIG. 3, and will not be described in detail herein.
  • step S550 the PDCP transmitting entity determines whether the PDCP PDU corresponding to the lower window of the transmission window is sent to the PDCP receiving entity of the user equipment (UE) through the SeNB. If yes, step S560 is performed, otherwise it ends.
  • Steps S560 and S570 are the same as steps S350 and S360 in the method 300 shown in FIG. 3, and will not be described in detail herein.
  • the transmission window size of the PDC transmitting entity is 6, and the PDCP PDU with the sequence number 0-5 has been sent and has not been confirmed whether the transmission is successful.
  • the PDCP PDUs with the sequence numbers 0 and 3 are sent by the RLC entity in the primary base station MeNB, and the PDCP PDUs with the sequence numbers 1, 2, 4, and 5 are transmitted by the RLC entity of the secondary base station SeNB.
  • the PDCP sending entity receives an indication message that the sequence number is 2, 4, and 5 is successfully sent from the SeNB.
  • the minimum sequence number of the PDCP PDU that has not been successfully transmitted is 0, and the maximum sequence number of the successfully transmitted PDCP PDU is 5.
  • step S520 step S530, step S540, step S550, and step S560
  • the PDCP transmitting entity starts a t-transmitting timer.
  • the PDCP sending entity receives an indication message that the PDCP PDU with sequence number 0 is successfully sent from the RLC entity located in the MeNB.
  • step S510 the PDCP sending entity updates the transmission window lower bound to 1.
  • the t-transmitting timer is restarted according to step S520, step S530, step S550, and step S560.
  • the PDCP transmitting entity updates the transmission window lower bound to the sub-minimum value 3 of the PDCP PDU that has not been acknowledged, and then restarts the t-Transmitting timer according to step S430 and step S440.
  • FIG. 6 is a flow diagram showing a method 600 of transmitting a PDCP PDU at yet another PDCP transmitting entity, in accordance with one or more embodiments of the present disclosure.
  • step S610 the t-Reordering timer of the PDCP receiving entity expires, and the PDCP receiving entity moves the receiving window as required.
  • the PDCP receiving entity sends an indication message to the corresponding PDCP sending entity, where the indication message carries the sequence number of the PDCP PDU corresponding to the t-Reordering timer initiated by the PDCP receiving entity. For example, assuming that the PDCP receiving entity receives the PDCP PDUs with the sequence numbers 0, 1, 3, 4, and 5, the PDCP receiving entity maps the PDCP PDUs with the sequence numbers 0 and 1 to the PDCP SDUs and delivers them to the upper layer.
  • the PDCP receiving entity sends an indication message to the PDCP sending entity, where the indication message includes the sequence number 2.
  • step S620 after receiving the indication message, the PDCP sending entity compares the lower boundary of the transmission window with the sequence number of the PDCP PDU indicated by the indication message. If the lower boundary of the transmission window is less than or equal to the sequence number carried in the indication message, then in step S630, the transmission window is moved, and the lower boundary of the transmission window is set to be larger than the sequence number of the PDCP PDU that is carried in the indication message and has not been confirmed.
  • the smallest sequence number in the number that is, the minimum sequence number position in the sequence number of the PDCP PDU whose mobile transmission window is larger than the sequence number carried in the indication message and has not been confirmed.
  • the PDCP receiving entity maintains a receive window and assists the PDCP to send the entity mobile transmit window through the t-Reordering timer, thus maintaining the superframe number synchronization of the PDCP transmitting entity and the PDCP receiving entity.
  • the SeNB after successfully transmitting the PDCP PDU from the upper PDCP sending entity located in the MeNB, the SeNB sends an indication message indicating that the PDCP PDU is successfully sent to the PDCP sending entity located in the MeNB.
  • the MeNB moves the window accordingly.
  • 7 is a flowchart of a method 700 of a secondary base station SeNB transmitting an indication message indicating that a PDCP PDU was successfully transmitted to a primary base station MeNB, in accordance with one or more embodiments of the present disclosure.
  • step S710 the SeNB receives the PDCP PDU to be transmitted from the MeNB.
  • step S720 the SeNB transmits at least one PDCP PDU and transmits successfully.
  • step S740 the SeNB sends an indication message indicating that the PDCP PDU is successfully transmitted to the MeNB.
  • step S730 the SeNB determines whether the sequence number is smaller than the maximum sequence number of the successfully transmitted PDCP PDU. The PDCP PDU has not been sent successfully. If not, step S740 is performed, otherwise, it ends.
  • step S740 an indication message indicating that the PDCP PDU is successfully transmitted is sent to the MeNB.
  • the SeNB can prevent the SeNB from generating and transmitting the indication message frequently, and reduce the signaling overhead of the Xn interface, by sending the indication message after the SeNB sends the indication message after the multiple PDCP PDUs are successfully sent, instead of sending the PDCP PDU. .
  • the indication message carries a sequence number of all PDCP PDUs that have been successfully transmitted.
  • the indication message carrying has been sent The minimum sequence number of the PDCP PDU of the function, a bitmap, and a bitmap length indication.
  • the bitmap is generated based on the serial number of the successfully transmitted PDCP PDU. For example, if the SeNB receives the PDCP PDUs with the sequence numbers 1, 2, 4, and 5 from the MeNB, and the PDCP PDUs with the sequence numbers 1, 2, and 4 have been successfully transmitted, the SeNB sends an indication message that the PDCP PDU is successfully sent to the MeNB.
  • the indication message carries sequence numbers 1, 2 and 4.
  • the indication message carries the PDCP PDU minimum sequence number 1, the bitmap length 3, and the bitmap shown in FIG. 8 that have been successfully transmitted.
  • each bit of the bitmap indicates whether the corresponding PDCP PDU is successfully transmitted.
  • a value of 1 indicates that the corresponding PDCP PDU has been successfully transmitted, and a value of 0 indicates that the corresponding PDCP PDU has not been received.
  • the first bit from left to right of the bitmap corresponds to the PDCP PDU with sequence number 2.
  • the value of 1 indicates that the PDCP PDU with sequence number 2 has been sent successfully.
  • the second bit corresponds to the PDCP PDU with sequence number 3. Since the SeNB does not send the PDCP PDU with sequence number 3, its value is 0.
  • the third bit corresponds to the PDCP PDU with sequence number 4.
  • the value of 1 indicates that the PDCP PDU with sequence number 4 has been successfully transmitted.
  • the PDCP PDUs transmitted in order from the MeNB always arrive at the SeNB in order, and are transmitted by the SeNB in order. According to the embodiment shown in FIG. 7, the SeNB will still generate an indication message indicating that the PDCP PDU is successfully sent, which results in a large signaling overhead of the Xn interface.
  • FIG. 9 is a flowchart of a method 900 of a secondary base station SeNB transmitting an indication message indicating that a PDCP PDU was successfully transmitted to a primary base station MeNB, in accordance with one or more embodiments of the present disclosure.
  • step S910 the SeNB receives the PDCP PDU to be transmitted from the MeNB.
  • step S920 a timer is started.
  • step S930 the SeNB transmits at least one PDCP PDU and the transmission is successful.
  • step S940 it is determined whether the timer expires. If the timer expires, step S950 is performed, otherwise, it ends.
  • step S950 an indication message indicating that the PDCP PDU is successfully transmitted is sent to the MeNB.
  • the time interval for transmitting the indication message indicating that the PDCP PDU is successfully transmitted is controlled by adding a timer indication_timer.
  • An indication message indicating that the PDCP PDU is successfully transmitted is sent to the MeNB when the timer expires.
  • the indication message indicates all PDCP PDUs that have been successfully transmitted.
  • the indication message only indicates that the PDCP PDU has been successfully sent, and the indicated PDCP PDU satisfies the condition that the PDCP PDU from the MeNB whose sequence number is smaller than the indicated PDCP PDU sequence number has been successfully sent. .
  • the SeNB receives PDCP PDUs with sequence numbers 1, 3, 4, 5, and 7 from the MeNB, and the indication_timer timer expires after successfully transmitting the PDCP PDUs with sequence numbers 1, 3, 4, and 7.
  • the SeNB may send all PDCP PDUs indicating that the message has been successfully sent to the MeNB, that is, the sequence number is 1, 3, 4, and 7 has been successfully transmitted.
  • the SeNB may also send a partial PDCP PDU indicating that the sequence has been successfully transmitted to the MeNB, that is, the sequence number is 1, 3, and 4 has been successfully transmitted (since the PDCP PDU with sequence number 5 is not yet successfully transmitted).
  • the setting of the timer indication_timer value needs to consider factors such as the size of the transmission window in the MeNB and the rate at which the PDCP PDU is transmitted to the two lower layer entities in the MeNB.
  • the PDCP receiving entity assists the PDCP in transmitting a physical mobile transmission window by maintaining a receive window and through a t-Reordering timer, ie, transmitting a subsequent PDCP PDU.
  • 10 is a flow diagram showing a method 1000 of confirming receipt of a PDCP PDU at a PDCP receiving entity in accordance with one or more embodiments of the present disclosure.
  • the PDCP receiving entity maintains a receive window whose lower bound indicates the minimum sequence number of the PDCP PDU that has not been received.
  • At step S1020 at least one PDCP PDU is received.
  • a timer is started if the sequence number of the received PDCP PDU is greater than the lower bound of the receive window but the sequence number falls within the receive window.
  • step S1040 if a PDCP PDU corresponding to the lower bound of the receive window is received, the receive window is moved and the timer is deleted.
  • step S1050 it is determined whether the expiration of the timer expires. If yes, then at step S1060, the receiving window is moved, and an indication message is sent to the primary base station transmitting the PDCP PDU to instruct the primary base station to move the transmission window, wherein the message includes the PDCP that has not been received yet. The minimum serial number of the PDU. Otherwise, continue to return to step S1020 to wait for receiving PDCP PDU.
  • the lower bound of the receive window is set to the second smallest sequence number of the PDCP PDU that has not been received when the timer expires.
  • the timer is a t-Reordering timer.
  • 11 is another flow diagram showing a method 1100 of transmitting a PDCP PDU at another PDCP transmitting entity, in accordance with one or more embodiments of the present disclosure.
  • the PDCP sending entity maintains a constant t-Transmittingtimer and variables Next_PDCP_Tx_SN, Max_PDCP_ACK_SN.
  • the Next_PDCP_Tx_SN is used to indicate the minimum sequence number of the PDCP PDU that has not been acknowledged to be successfully transmitted, that is, the lower bound of the transmission window.
  • Max_PDCP_ACK_SN is used to indicate the maximum sequence number of the PDCP PDU that is currently acknowledged to have been successfully transmitted.
  • step S1101 the PDCP sending entity receives an indication message that the PDCP PDU is successfully transmitted from the lower layer entity and updates the Max_PDCP_ACK_SN to the maximum sequence number of the successfully transmitted PDCP PDU.
  • step S1102 the PDCP sending entity determines whether the minimum sequence number of the successfully transmitted PDCP PDU indicated in the indication message is the lower threshold of the transmission window. If yes, step S1103 is performed; otherwise, step S1111 is performed.
  • step S1103 the PDCP transmitting entity updates Next_PDCP_Tx_SN to the new minimum sequence number of the PDCP PDU that has not been acknowledged to be successfully transmitted.
  • step S1104 the PDCP transmitting entity determines whether the maximum sequence number of the PDCP PDU that has been successfully transmitted (ie, the variable Max_PDCP_ACK_SN) is greater than Next_PDCP_Tx_SN. If it is greater, step S1105 is performed; otherwise, step S1109 is performed.
  • step S1105 the PDCP transmitting entity determines whether the PDCP PDU whose sequence number is Next_PDCP_Tx_SN is sent to the PDCP receiving entity of the UE through the SeNB. If yes, step S1106 is performed, otherwise step S1109 is performed.
  • step S1106 it is determined whether there is a running timer. If yes, step S1107 is performed, otherwise step S1108 is performed.
  • step S1107 the t-Transmitting timer is restarted.
  • step S1108 the t-Transmitting timer is started.
  • step S1109 it is determined whether there is a running t-transmitting timer. If there is, Then step S1110 is performed, otherwise the method ends.
  • step S1110 the running t-Transmitting timer is deleted.
  • step S1111 it is judged whether or not the PDCP PDU whose sequence number is Next_PDCP_Tx_SN is transmitted to the seNB. If yes, the method ends. Otherwise, step S1112 is performed.
  • step S1112 it is determined whether there is a running t-transmitting timer. If so, the method ends, otherwise step S1113 is performed.
  • step S1113 the t-Transmitting timer is started.
  • the judgment as to whether or not there is a packet loss is achieved by maintaining a variable.
  • FIG. 12 is a schematic block diagram showing a PDCP transmitting entity 2000 in accordance with one or more embodiments of the present disclosure.
  • the PDCP transmitting entity 2000 includes: a timer 2010; a receiver 2020; a transmission window moving unit 2030; and a timer controller 2040.
  • the receiver 2020 is configured to receive an indication message that the PDCP PDU was successfully transmitted.
  • Transmit window mobile unit 2030 is configured to move the transmit window based on the sequence number of the successfully transmitted PDCP PDU indicated in the indication message.
  • the timer controller 2040 is configured to determine whether there is a PDCP PDU whose sequence number is greater than the lower bound of the transmission window that is confirmed to have been successfully transmitted, and determine that there is a sequence number greater than the transmission window that is confirmed to have been successfully transmitted.
  • the timer 2010 is started when the lower bound PDCP PDU.
  • the transmit window mobile unit 2030 is further configured to: when the timer 2010 expires, move the transmit window.
  • the transmit window mobile unit 2030 is further configured to set the lower bound of the transmit window to the second minor sequence number of the PDCP PDU that has not been acknowledged to be successfully transmitted when the timer 2010 expires.
  • the timer controller 2030 is further configured to determine whether the transmit window has been moved. If the transmission window is moved, the timer 2010 is started if the timer 2010 is not started, or the timer 2010 is restarted if the timer 2010 has been started;
  • the timer 2010 is started without the timer 2010 being started.
  • the timer controller 2030 is further configured to delete the running timer 2010 if it is determined that there is no PDCP PDU whose sequence number is greater than the lower bound of the transmit window that was confirmed to have been successfully transmitted. .
  • the timer controller 2030 is further configured to: determine whether a PDCP PDU corresponding to a lower boundary of the transmission window is transmitted to the secondary base station. If yes, the timer is started; otherwise, the timer is not operated.
  • the expiration value of the timer 2010 is set according to a t-Reordering timer of the PDCP receiving entity that receives the PDCP PDU from the PDCP entity.
  • the indication message includes a sequence number of all PDCP PDUs that were successfully transmitted.
  • the indication message includes: a minimum sequence number of the successfully transmitted PDCU PDU, a bitmap, and a bitmap length indication, each bit in the bitmap indicating whether the corresponding PDCP PDU is successfully sent.
  • the sequence number of the PDCP PDU corresponding to each bit in the bitmap is the minimum sequence number of the successfully transmitted PDCP PDU plus the value of the bit in the bitmap.
  • FIG. 13 is a schematic block diagram showing a schematic configuration of a secondary base station 3000 of one or more embodiments of the present disclosure.
  • the secondary base station 3000 includes a receiver 3010 and a transmitter 3030.
  • Receiver 3010 is configured to receive PDCP PDUs to be transmitted from the primary base station, each PDCP PDU having a sequence number.
  • the transmitter 3030 is configured to, after successfully transmitting the at least one PDCP PDU, send a message to the primary base station indicating that the PDCP PDU was successfully transmitted, the message indicating the sequence number of the successfully transmitted PDCP PDU.
  • the secondary base station 3000 may further include a determining unit 3020.
  • the determining unit 3020 is configured to, after successfully transmitting the at least one PDCP PDU, be configured to determine whether a PDCP PDU having a sequence number smaller than the successfully transmitted PDCP PDU sequence number has not been successfully transmitted.
  • the transmitter 3030 is further configured to: after the determining unit determines that the PDCP PDU having no sequence number smaller than the successfully transmitted PDCP PDU sequence number has not been successfully sent, send to the primary base station A message indicating that the PDCP PDU was successfully sent.
  • the secondary base station 3000 can include a timer 3040 and a timer controller 3050.
  • the timer controller 3050 is configured to activate the timer 3040 upon receiving a PDCP PDU to be transmitted from the primary base station.
  • the transmitter 3030 is further configured to, after successfully transmitting the at least one PDCP PDU, wait for the timer 3040 to expire before transmitting a message to the primary base station indicating that the PDCP PDU was successfully transmitted.
  • the message includes a sequence number of all PDCP PDUs that were successfully transmitted.
  • the message includes: a minimum sequence number of the successfully transmitted PDCU PDU, a bitmap, and a bitmap length indication, each bit in the bitmap indicating whether the corresponding PDCP PDU is successfully sent.
  • the sequence number of the PDCP PDU corresponding to each bit in the bitmap is the minimum sequence number of the successfully transmitted PDCP PDU plus the value of the bit in the bitmap.
  • the message indicates only a portion of the PDCP PDU that has been successfully transmitted, wherein the PDCP PDU from the primary base station having a sequence number smaller than the sequence number of the indicated partial PDCP PDU has been successfully transmitted.
  • FIG. 14 is a schematic block diagram showing a user equipment 4000 of one or more embodiments of the present disclosure.
  • the user equipment 4000 includes a memory 4010, a receiver 4020, a timer 4030, a timer controller 4040, a receiving window moving unit 4050, and a transmitter 4060.
  • the memory 4010 is configured to maintain a receive window whose lower bound indicates the minimum sequence number of the PDCP PDU that has not been received.
  • Receiver 4020 is configured to receive at least one PDCP PDU.
  • the timer controller 4040 is configured to start the timer 4030 when the receiver receives a PDCP PDU whose sequence number is greater than the lower bound of the receive window but the sequence number falls within the receive window, and when the receiver receives When the PDCP PDU corresponding to the lower boundary of the window is received, the timer 4030 is deleted.
  • the receive window moving unit 4050 is configured to move the receive window when the receiver 4020 receives a PDCP PDU corresponding to a lower bound of the receive window or when the timer 4030 expires.
  • the transmitter 4060 is configured to, when the timer 4030 expires, send an indication message to the primary base station from which the received PDCP PDU is sent to instruct the primary base station to move the transmission window, wherein the message includes a location that has not been received.
  • the minimum sequence number of at least one PDCP PDU is configured to, when the timer 4030 expires, send an indication message to the primary base station from which the received PDCP PDU is sent to instruct the primary base station to move the transmission window, wherein the message includes a location that has not been received.
  • the minimum sequence number of at least one PDCP PDU is configured to, when the timer 4030 expires, send an indication message to the primary base station from which the received PDCP PDU is sent to instruct the primary base station to move the transmission window, wherein the message includes a location that has not been received.
  • the receive window move unit 4050 is configured to set the lower bound of the receive window to the sub-sequence number of the PDCP PDU that has not been received when the timer 4030 expires.
  • FIG. 15 is a schematic block diagram showing a PDCP transmitting entity 5000 according to one or more embodiments of the present disclosure.
  • the PDCP transmitting entity 5000 includes a receiver 5010 and a transmission window moving unit 5020.
  • the receiver 5010 is configured to receive a Receiver Indication message from a PDCP receiving entity, the Receiver Indication message indicating a minimum sequence number of PDCP PDUs not received by the PDCP receiving entity.
  • the transmit window moving unit 5020 is configured to compare a lower boundary of a transmit window maintained by the PDCP sending entity with a sequence number of the PDCP PDU indicated by the receive end indication message; if a lower bound of the transmit window is less than or equal to the receive end indication The sequence number of the PDCP PDU indicated by the message moves the lower bound of the transmission window to be the smallest sequence number in the sequence number of the PDCP PDU that is greater than the sequence number carried in the receiving end indication message and has not been confirmed.
  • the transmission window can be moved even if packet loss occurs on the Xn interface, so the PDCP Tx can still transmit new data without affecting the wireless. Link transmission delay and reliability.
  • the PDCP sending entity moves the transmission window by maintaining a receiving window by the DCP receiving entity and by using a t-Reordering timer, so that the transmission window can be moved even if packet loss occurs on the Xn interface, Moreover, the superframe number synchronization of the PDCP transmitting entity and the PDCP receiving entity is maintained.
  • the computer program product is an embodiment having a computer readable medium encoded with computer program logic, the computer program logic providing related operations when provided on a computing device to provide The above technical solution.
  • Computer program logic enables when executed on at least one processor of a computing system The processor executes the operations (methods) described in the embodiments of the present disclosure.
  • Such an arrangement of the present disclosure is typically provided as software, code, and/or other data structures, such as one or more, that are arranged or encoded on a computer readable medium such as an optical medium (eg, CD-ROM), floppy disk, or hard disk.
  • Software or firmware or such a configuration may be installed on the computing device such that one or more processors in the computing device perform the techniques described in the embodiments of the present disclosure.
  • Software processes in conjunction with computing devices such as a group of data communication devices or other entities may also provide devices in accordance with the present disclosure.
  • Devices in accordance with the present disclosure may also be distributed among multiple software processes on multiple data communication devices, or all software processes running on a group of small dedicated computers, or all software processes running on a single computer.
  • embodiments of the present disclosure may be implemented as software programs, software and hardware on a computer device, or as separate software and/or separate circuits.

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Abstract

本公开提出了一种机制，使得PDCP发送实体能够在Xn接口发生丢包后仍可移动发送窗。根据实施例，在PDCP发送实体中设置定时器，在确定可能发生丢包时启动定时器。在定时器期满时移动发送窗，而无论发送窗下界的PDCP PDU是否被确认已发送成功。根据另外的实施例，通过由DCP接收实体维护一个接收窗且通过t-Reordering定时器来辅助PDCP发送实体移动发送窗，这样即使在Xn接口上发生丢包，仍然可以移动发送窗，继续发送后续PDCP PDU。

Description

PDCP发送实体、辅基站、用户设备及其方法 技术领域
本公开涉及移动通信，具体地，涉及分组数据汇聚协议PDCP发送实体、辅基站、PDCP接收实体、PDCP发送实体处的发送分组数据汇聚协议协议数据单元(PDCP PDU)的方法、辅基站向主基站报告PDCP PDU发送成功的方法以及PDCP接收实体确认PDCP PDU接收成功的方法，以便PDCP发送实体的发送窗与PDCP接收实体的接收窗同步移动。
背景技术
第三代伙伴计划(3GPP)长期演进(LTE)***的层2(layer 2)用户平面协议栈(User-Plane Protocol Stack)由3个子层组成，从高到低依次为：分组数据汇聚协议(Packet Data Convergence Protocol，PDCP)层、无线链路控制(Radio Link Control，RLC)层和媒体接入控制(Media Access Control)层。在发送实体，从高层接收服务数据单元(Service Data Unit，SDU)，为该层提供业务，并向低层输出协议数据单元(Protocol Data Unit，PDU)。例如：RLC层接收来自PDCP的分组(packet)。这些分组对PDCP层来说是PDCP PDU，但对RLC层来说是RLC SDU。用于发送PDCP PDU的PDCP实体称为PDCP Tx，用于发送RLC PDU的RLC实体称为RLC Tx。在接收端，该过程是相反的，每层向上层发送SDU，上层作为PDU接收。用于接收PDCP PDU的PDCP实体称为PDCP Rx，用于接收RLC PDU的RLC实体称为RLC Rx。PDCP SDU由PDCP序列号(sequence number，SN)标识，PDCP SDU与对应的PDCP PDU和RLC SDU具有相同的序列号，RLC PDU由RLC序列号标识。PDCP序列号和RLC序列号可循环利用。当PDCP序列号达到最大值时，新的PDCP SDU又从最小值开始编号，但对应的超帧号增加1。PDCP序列号和超帧号(Hyper Frame Number，HFN)组成的COUNT唯一标识一个PDCP SDU。
3GPP LTE版本11中，每一无线承载(bearer)有一个PDCP实体(entity) 和一个RLC实体。每个基站(也称为NodeB或演进NodeB(eNB))和每个用户设备(UE)均有一个MAC实体。这里，用户设备可以是用户终端、用户节点、移动终端或平板电脑。正在制定中的3GPPLTE版本12标准中，包含关于具有双连接(dual connectivity)能力的用户设备、主基站(Master eNB，MeNB)、辅基站(Secondary eNB，SeNB)的标准制定工作。主基站负责维护用户设备的无线资源管理(Radio Resource Management，RRM)测量配置并且基于接收到的测量报告或流量状况(traffic conditions)或承载类型(bear type)向辅基站请求为用户设备提供额外的资源。辅基站接收到主基站的请求后为用户设备配置服务小区或因没有足够的资源而拒绝所述请求。
基于承载分离(bearer split)的不同方式和用户平面协议栈的不同，在3GPP TSG-RAN2第83bis次会议上，确定1A和3C两种用户平面架构(User-plane Architecture)作为双连接部署方式的标准化选项。在3GPP TR36.842中公开了相关内容，将其全部通过引用的方式并入本申请。图1示出的选项3C具有如下特征：(1)主基站(Master eNB，也称为MeNB)通过S1-U接口与业务网关(Serving Gateway，S-GW)通信；(2)承载在主基站中分离；(3)对于分离承载(split bearer)，在主基站和辅基站(Secondary eNB，也称为SeNB)中都有对应RLC实体(entity)。在选项3C中，位于辅基站的RLC实体与上层(即位于主基站的PDCP实体)通过Xn接口进行交互，所述Xn接口包括X2接口。相应的，具有双连接能力的用户设备为分离承载配置一个PDCP实体和两个RLC实体，所述PDCP实体与MeNB中的PDCP实体对应，所述两个RLC实体中的一个RLC实体与MeNB中的RLC实体对应，另一个RLC实体与SeNB中的RLC实体对应。
在3GPP LTE版本11中，由于每个PDCP Rx只对应一个RLC Rx。RLC接收实体的重排序功能确保PDCP Rx从RLC层按照顺序接收PDCP PDU。但在承载分离的双连接部署方式下，一个PDCP Rx对应两个RLC Rx，PDCP Rx从两个RLC Rx接收到的PDCP PDU是乱序的。因此，PDCPRx需要对来自两个RLC Rx的PDCP PDU重新进行排序。在3GPP TSG RAN WG2Meeting#85次会议上提出PDCP重排功能将采用UM RLC类似的基 于t-Reordering定时器的重排方法。在3GPP TR36.300中公开了该重排方法，将其全部通过引用的方式并入本申请。所述方法的主要思想为：PDCP Rx维护一个接收窗(receiving window)，也称为重排序窗(reordering window)，所述接收窗的大小为PDCP PDU序列号空间的一半。PDCP Rx从两个RLC Rx接收PDCP PDU，并将接收到的序列号不在接收窗内的PDCP PDU丢弃。当接收到未按照顺序到达但序列号落入接收窗内的PDCP PDU时，将所述PDCP PDU存储在重排序缓冲区中，并启动t-Reordering定时器，等待遗漏的PDCP PDU到来。当接收到遗漏的PDCP PDU，则将已按照顺序接收的PDCP SDU递交到上层；或者当所述t-Reordering定时器期满时，将除所述t-Reordering定时器对应的未按照顺序到达的PDCP SDU外的其他已按照顺序到达的PDCP SDU递交到上层。同时，将接收窗的下界置为已递交到上层的PDCP SDU最大序列号加1。为确保PDCP Tx和PDCP Rx的超帧号保持同步，相应的，在PDCP Tx处需要确保已经发送但尚未被确认的PDCP PDU的最大序列号和最小序列号的差值小于序列号空间的一半。且PDCP Tx只能发送序列号在已经发送但尚未被确认的PDCP PDU的最小序列号和所述最小序列号加上序列号空间一半再减去1所得的值之间的PDCP PDU。对于双链接模式的下行链路来说，位于SeNB的RLC Tx须通过Xn接口向位于MeNB的PDCP Tx发送PDCP PDU发送成功的指示消息，以便所述PDCP Tx能发送更多的PDCP PDU。此外，当PDCP Tx将PDCP PDU通过Xn接口发送给位于SeNB的RLC Tx时，数据可能丢失。位于SeNB的RLC Tx由于未收到该数据而无法给PDCP Tx发送确认消息，这将导致PDCP Tx在发送完所丢失的PDCP PDU及后续可发送的PDCP PDU(其序列号大于所丢失的PDCP PDU的序列号且小于所丢失的PDCP PDU的序列号加上序列号空间的一半所得的值)后，无法再发送新的PDCP PDU，进而影响无线链路的传输时延和可靠性。
发明内容
鉴于现有技术中存在的以上问题，本发明旨在提供一种机制，使得PDCP发送实体能够在Xn接口发生丢包后仍可移动发送窗，继续发送后 续的PDCP PDU。
根据本公开的一个方面，提出了一种分组数据汇聚协议(PDCP)发送实体处的发送分组数据汇聚协议协议数据单元(PDCP PDU)的方法，包括：在接收到PDCP PDU发送成功的指示消息时：根据指示消息中指示的已成功发送的PDCP PDU的序列号来移动发送窗，使得发送窗的下界指示未被确认发送成功的PDCP PDU的最小序列号。该方法还包括：确定是否存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU。如果存在，则启动定时器。
根据一个或多个实施例，当所述定时器期满时，移动所述发送窗。
根据一个或多个实施例，当所述定时器期满时，将所述发送窗的下界设置为还未被确认发送成功的PDCP PDU的次小序列号；以及确定是否存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU。如果存在，则启动所述定时器。
根据一个或多个实施例，如果确定不存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU，则删除正在运行的定时器。
根据一个或多个实施例，在启动所述定时器之前，判断所述发送窗的下界所对应的PDCPPDU是否被发送给辅基站。如果是，则启动所述定时器；否则，不对所述定时器进行操作。
根据本公开的另一个方面，提出了一种分组数据汇聚协议(PDCP)发送实体处的发送分组数据汇聚协议协议数据单元(PDCP PDU)的方法，包括：从PDCP接收实体接收接收端指示消息，所述接收端指示消息指示所述PDCP接收实体未接收到的PDCP PDU的最小序列号；比较所述发送窗的下界与所述接收端指示消息所指示的PDCP PDU的序列号；如果所述发送窗的下界小于或等于所述接收端指示消息所指示的PDCP PDU的序列号，则将所述发送窗的下界移动至大于所述接收端指示消息中携带的序列号、且尚未被确认的PDCP PDU的序列号中的最小序列号。
根据本公开的又一个方面，提出了一种分组数据汇聚协议(PDCP)接收实体处的确认分组数据汇聚协议协议数据单元(PDCP PDU)的接收成功的方法，包括：维护一个接收窗，所述接收窗的下界指示尚未接收到的PDCP PDU的最小序列号；当接收到序列号大于所述接收窗的下界但序 列号落入接收窗内的PDCP PDU时，启动定时器；当接收到接收窗下界对应的PDCP PDU时，移动所述接收窗并删除所述定时器；当所述定时器期满时，移动所述接收窗，并向发送所述PDCP PDU的主基站发送指示消息，以指示所述主基站移动发送窗，其中，所述消息包含尚未接收到的PDCP PDU的所述最小序列号。
根据一个或多个实施例，当所述定时器期满时，将所述接收窗的下界设置为尚未接收到的PDCP PDU的次小序列号。
根据本公开的再一个方面，提出了一种辅基站处的确认分组数据汇聚协议协议数据单元(PDCP PDU)发送成功的方法，包括：从主基站接收要发送的PDCP PDU，每个PDCP PDU均具有序列号；以及在成功地发送了至少一个PDCP PDU之后，向主基站发送指示PDCP PDU发送成功的消息，所述消息指示被成功发送的PDCP PDU的序列号。
根据本公开的还一个方面，提出了一种分组数据汇聚协议PDCP发送实体，包括：定时器；接收器，被配置为接收分组数据汇聚协议协议数据单元(PDCP PDU)发送成功的指示消息；发送窗移动单元，被配置为根据指示消息中指示的已成功发送的PDCP PDU的序列号来移动发送窗；以及定时器控制器，被配置为确定是否存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU，并在确定存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU时启动所述定时器。
根据本公开的其它一个方面，提出了一种分组数据汇聚协议PDCP发送实体，包括：接收器，被配置为从PDCP接收实体接收接收端指示消息，所述接收端指示消息指示所述PDCP接收实体未接收到的分组数据汇聚协议协议数据单元(PDCP PDU)的最小序列号；以及发送窗移动单元，被配置为比较所述PDCP发送实体所维护的发送窗的下界与所述接收端指示消息所指示的PDCP PDU的序列号；如果所述发送窗的下界小于或等于所述接收端指示消息所指示的PDCP PDU的序列号，则将所述发送窗的下界移动至大于所述接收端指示消息中携带的序列号、且尚未被确认的PDCP PDU的序列号中的最小序列号。
根据本公开的又再一个方面，提出了一种用户设备，包括：存储器，被配置为维护一个接收窗，所述接收窗的下界指示尚未接收到的分组数据 汇聚协议协议数据单元(PDCP PDU)的最小序列号；接收器，被配置为接收至少一个PDCP PDU；定时器；定时器控制器，被配置为当所述接收器接收到序列号大于所述接收窗的下界但序列号落入接收窗内的PDCP PDU时，启动所述定时器，并且当所述接收器接收到接收窗下界对应的PDCP PDU时，删除所述定时器；接收窗移动单元，被配置为当所述接收器接收到接收窗下界对应的PDCP PDU或者当所述定时器期满时，移动所述接收窗；以及发送器，被配置为当所述定时器期满时，向接收到的PDCP PDU所来自的主基站发送指示消息，以指示所述主基站移动发送窗，其中，所述消息包含尚未接收到的所述至少一个PDCP PDU的最小序列号。
根据本公开的其它一个方面，提出了一种与主基站协作的辅基站，包括：接收器，被配置为从主基站接收要发送的分组数据汇聚协议协议数据单元(PDCP PDU)，每个PDCP PDU均具有序列号；发送器，被配置为在成功地发送了至少一个PDCP PDU之后，向主基站发送指示PDCP PDU发送成功的消息，所述消息指示成功发送的PDCP PDU的序列号。
根据本公开的一个或多个实施例，通过在PDCP发送实体中设置定时器，即使在Xn接口上发生丢包，仍然可以移动发送窗，即PDCP Tx仍然可以发送新的数据，不会影响无线链路的传输时延和可靠性。根据本公开的另外一些实施例，通过由DCP接收实体维护一个接收窗且通过t-Reordering定时器来辅助PDCP发送实体移动发送窗，这样即使在Xn接口上发生丢包，仍然可以移动发送窗，而且保持了PDCP发送实体和PDCP接收实体的超帧号同步。
附图说明
通过下文结合附图的详细描述，本公开的上述和其它特征将会变得更加明显，其中：
图1为3GPP TR36.842中给出的双连接部署选项3C的示意图。
图2示出了根据本公开的一个或多个实施例的PDCP发送实体处的发送PDCP PDU的方法的流程图。
图3是示出了根据本公开的一个或多个实施例的另一PDCP发送实体处的发送PDCP PDU的方法的另一流程图。
图4是示出了根据本公开的一个或多个实施例的操作t-Transmitting定时器的方法的流程图。
图5是示出了根据本公开的一个或多个实施例的另一PDCP发送实体处的发送PDCP PDU的方法的另一流程图。
图6是示出了根据本公开的一个或多个实施例的又一PDCP发送实体处的发送PDCP PDU的方法的流程图。
图7给出了根据本公开的一个或多个实施例的辅基站SeNB向主基站MeNB发送指示PDCP PDU发送成功的指示消息的方法的流程图。
图8是示出了位图的一个示例。
图9给出了根据本公开的一个或多个实施例的辅基站SeNB向主基站MeNB发送指示PDCP PDU发送成功的指示消息的方法的流程图。
图10是示出了根据本公开的一个或多个实施例的PDCP接收实体处的确认PDCP PDU接收成功的方法的流程图。
图11是示出了根据本公开的一个或多个实施例的另一PDCP发送实体处的发送PDCP PDU的方法的另一流程图。
图12是示出了本公开的一个或多个实施例的PDCP发送实体的示意结构方框图。
图13是示出了本公开的一个或多个实施例的辅基站的示意结构方框图。
图14是示出了本公开的一个或多个实施例的用户设备的示意结构方框图。
图15是示出了根据本公开的一个或多个实施例的PDCP发送实体的示意结构方框图。
具体实施方式
下面，通过结合附图对本公开的具体实施例的描述，本发明的原理和实现将会变得明显。应当注意的是，本发明不应局限于下文所述的具体实施例。另外，为了简便起见，省略了对与本发明没有直接关联的公知技术的详细描述，以防止对本发明的理解造成混淆。
下文以LTE Rel-12移动通信***及其后续的演进版本作为示例应用 环境，具体描述了根据本公开的多个实施例。然而，需要指出的是，本公开不限于以下实施例，而可以适用于更多其它的无线通信***，例如今后的5G蜂窝通信***。
图2是示出了根据本公开的一个或多个实施例的PDCP发送实体处的发送PDCP PDU的方法200的流程图。为便于描述，本公开的一个或多个实施例采用类似RLC实体采用的发送窗的方法来描述当前的PDCP PDU发送空间。但是，本发明并不局限于采用所述发送窗的描述方式来描述当前可发送的PDCP PDU。
图2所述方法在PDCP发送实体维护一个发送窗(transmitting window)，发送窗的下界对应还未被确认发送成功的PDCP PDU的最小序列号。通过发送窗的下界和上界限定当前可发送的PDCP PDU。发送窗的下界为可发送的PDCP PDU的最小序列号；发送窗的上界为可发送的PDCP PDU的最大序列号+1。发送窗的大小为PDCP PDU序列号空间的一半。PDCP Tx只能发送序列号在发送窗内的PDCP PDU。发送窗的移动依赖于从分别位于MeNB和SeNB的两个RLC实体接收到已成功发送的确认消息。需要说明的是，此处及本公开其他部分所涉及的序列号的比较是指序列号所对应的COUNT值的比较，所涉及的序列号的加减计算也是指序列号所对应的COUNT值的加减计算。
首先，在步骤S210处，PDCP发送实体接收PDCP PDU发送成功的指示消息。PDCP发送实体根据指示消息来移动其发送窗，使得发送窗的下界指示未被确认发送成功的PDCP PDU的最小序列号。
接下来，在步骤S220处，确定是否存在已被确认发送成功的、序列号大于发送窗的下界的PDCP PDU。
如果在步骤S220处确定存在已被确认发送成功的、序列号大于发送窗的下界的PDCP PDU，则在步骤S230处，启动定时器。否则，在步骤S240处，如果定时器正在运行，则删除定时器。
根据本公开的一个或多个实施例，引入定时器，在可能发生丢包时启动定时器。这样，通过适当地设置定时器的期满值，在定时器期满时进行适当操作，从而在发生丢包时仍可移动发送窗。
图3是示出了根据本公开的一个或多个实施例的另一PDCP发送实体 处的发送PDCP PDU的方法300的另一流程图。
首先，PDCP发送实体维护常量t-Transmittingtimer。t-Transmittingtimer是t-Transmitting定时器的值。根据一个或多个实施例，PDCP发送实体的t-Transmitting定时器的取值依赖于对应的PDCP接收实体处的t-Reordering定时器的值。例如：可以将t-Transmittingtimer设置为与t-Reordering定时器的值相同或比t-Reordering定时器的值略小的值。本公开的实施例中，所述序列号大小的比较均指所述序列号对应的COUNT值的比较。
如图3所示，在步骤S310中，PDCP发送实体从下层实体接收PDCP PDU发送成功的指示消息并根据指示消息来移动发送窗。如果指示消息指示当前发送窗的下界所对应的PDCP SDU已发送成功，则PDCP发送实体更新发送窗的下界为新的还未被确认发送成功的PDCP PDU的最小序列号。
在步骤S320中，PDCP发送实体确定是否存在已被确认发送成功的、序列号大于发送窗的下界的PDCP PDU。如果是，则执行步骤S330；否则，执行步骤S360。
在步骤S330中，PDCP发送实体根据步骤S310中是否更新了发送窗的下界来执行相应的操作。如果发送窗的下界已被更新，则执行步骤S350；否则，执行步骤S340。
在步骤S340中，PDCP发送实体确定是否有正在运行的t-Transmitting定时器。如果没有，则执行步骤S350。
在步骤S350中，PDCP发送实体启动或重启t-Transmitting定时器，即如果t-Transmitting定时器正在运行，则重启t-Transmitting定时器，否则，启动t-Transmitting定时器。
在步骤S360中，PDCP发送实体判断t-Transmitting定时器是否正在运行中，如果是，则删除所述正在运行的定时器。
根据本公开的一个或多个实施例，引入定时器，在可能发生丢包时启动该包对应的定时器。这样，通过适当地设置定时器的期满值，在定时器期满时进行适当操作，从而在发生丢包时仍可移动发送窗。
图4是示出了根据本公开的一个或多个实施例的操作t-Transmitting 定时器的方法400的流程图。
在该方法开始之后，在步骤S410处确认t-Transmitting定时器是否期满。
如果是，则前进至步骤S420，移动发送窗。根据一个或多个实施例，图步骤S420所示，将发送窗下界设置为还未被确认发送成功的PDCP PDU的次小序列号，即除所述t-Transmitting定时器对应的PDCP PDU外的还未被确认发送成功的PDCP PDU的最小序列号。
然后，在步骤S430处，比较已发送成功的PDCP PDU的最大序列号与发送窗下界对应的PDCP PDU的序列号。
如果已发送成功的PDCP PDU的最大序列号大于发送窗下界对应的PDCP PDU的序列号，则在步骤S440处，再次重启t-Transmitting定时器。否则，不再设置t-Transmitting定时器。该方法结束。
在该实施例中，如果t-Transmitting定时器期满，则将发送窗的下界设置为除所述t-Transmitting定时器对应的PDCP PDU外的还未被确认发送成功的PDCP PDU的最小序列号。此时，如果已发送成功的PDCP PDU最大序列号大于更新后的发送窗下界，即，还存在可能被丢失的分组，则再次启动t-Transmitting定时器。根据该实施例，即使可能发生丢包，在定时器期满时移动发送窗。因此，可以避免由于丢包而使得发送窗停滞不前的情形。
在LTE版本12中双链接部署方式仅适用于RLC确认模式(RLC Acknowledge Mode)。在RLC确认模式下，位于MeNB的RLC实体总能确保来自上层的所有PDCP PDU正确发送。因此，为避免频繁的启动t-Transmitting定时器，PDCP发送实体可以只对通过SeNB发送的PDCP PDU启动t-Transmitting定时器，即如果尚未被确认的序列号最小的PDCP PDU(发送窗下界)是通过SeNB发送且所述PDCP PDU序列号小于已发送成功的PDCP PDU的最大序列号，则启动t-Transmitting定时器。
图5是示出了根据本公开的一个或多个实施例的另一PDCP发送实体处的发送PDCP PDU的方法500的另一流程图。
步骤S510、S520、S530、S540与图3所示的方法300中的步骤S310、S320、S330、S340相同，在此不再详述。
在步骤S550中，PDCP发送实体确定发送窗下界对应的PDCP PDU是否通过SeNB发送给用户设备(UE)的PDCP接收实体。如果是，则执行步骤S560，否则结束。
步骤S560、S570与图3所示的方法300中的步骤S350、S360相同，在此不再详述。
例如：假设PDC发送实体的发送窗大小为6，序列号为0-5的PDCP PDU已经发送且尚未被确认是否发送成功。其中，序列号为0、3的PDCP PDU通过主基站MeNB中的RLC实体发送，序列号为1，2，4，5的PDCP PDU通过辅基站SeNB的RLC实体发送。经过一段时间后，PDCP发送实体从SeNB接收到序列号为2、4、5发送成功的指示消息。此时，尚未被确认是否发送成功的PDCP PDU最小序列号为0且已发送成功的PDCP PDU最大序列号为5。根据步骤S520、步骤S530、步骤S540、步骤S550以及步骤S560，PDCP发送实体启动t-Transmitting定时器。又经一段时间后，PDCP发送实体从位于MeNB中RLC实体接收到序列号为0的PDCP PDU发送成功的指示消息。根据步骤S510，PDCP发送实体更新发送窗下界为1。根据步骤S520、步骤S530、步骤S550以及步骤S560，重启t-Transmitting定时器。如果t-Transmitting定时器期满，根据步骤S420，PDCP发送实体将发送窗下界更新为还未被确认的PDCP PDU的次最小值3，然后根据步骤S430和步骤S440，重启t-Transmitting定时器。
图6是示出了根据本公开的一个或多个实施例的又一PDCP发送实体处的发送PDCP PDU的方法600的流程图。
如图6所示，在步骤S610中，PDCP接收实体的t-Reordering定时器期满，PDCP接收实体按照要求移动接收窗。PDCP接收实体向对应的PDCP发送实体发送指示消息，所述指示消息中携带PDCP接收实体启动的t-Reordering定时器所对应的PDCP PDU的序列号。例如，假设PDCP接收实体接收到序列号为0、1、3、4、5的PDCP PDU，PDCP接收实体将序列号为0、1的PDCP PDU映射为PDCP SDU后递交给上层。由于序列号为3、4、5的PDCP PDU不是按照顺序接收，将这些PDCP PDU本地保存，同时启动t-Reordering定时器。当t-Reordering定时器期满时，PDCP接收实体向PDCP发送实体发送指示消息，所述指示消息中包含序列号2。
在步骤S620中，PDCP发送实体接收到所述指示消息后，比较发送窗下界与所述指示消息所指示的PDCP PDU的序列号。如果发送窗的下界小于或等于指示消息中携带的序列号，则在步骤S630，移动发送窗，将发送窗的下界设置为大于指示消息中携带的序列号、且尚未被确认的PDCP PDU的序列号中的最小序列号，即移动发送窗到大于指示消息中携带的序列号且尚未被确认的PDCP PDU的序列号中的最小序列号位置。
根据该实施例，PDCP接收实体维护一个接收窗且通过t-Reordering定时器来辅助PDCP发送实体移动发送窗，这样保持了PDCP发送实体和PDCP接收实体的超帧号同步。
在如图3-5所示的一个或多个实施例中，SeNB在成功发送来自位于MeNB的上层PDCP发送实体的PDCP PDU后，向位于MeNB的PDCP发送实体发送指示PDCP PDU发送成功的指示消息，以便MeNB相应的移动发送窗。图7给出了根据本公开的一个或多个实施例的辅基站SeNB向主基站MeNB发送指示PDCP PDU发送成功的指示消息的方法700的流程图。
如图7所示，在步骤S710中，SeNB从MeNB接收到要发送的PDCP PDU。
在步骤S720中，SeNB发送至少一个PDCP PDU，并发送成功。
然后，在步骤S740中，SeNB向MeNB发送指示PDCP PDU发送成功的指示消息。
在图7所示的流程图中，在步骤S740中SeNB向MeNB发送指示消息之前，还存在步骤S730，在步骤S730中，SeNB判断是否存在序列号小于已发送成功的PDCP PDU的最大序列号的PDCP PDU还未发送成功。如果不存在，则执行步骤S740，否则，结束。
在步骤S740中，向MeNB发送指示PDCP PDU发送成功的指示消息。
通过使得SeNB在成功发送多个按照顺序的PDCP PDU之后发送指示消息而不是每次成功发送一个PDCP PDU就发送指示消息，可以避免SeNB频繁地生成和发送指示消息，减小Xn接口的信令开销。
根据一个或多个实施例，所述指示消息携带已发送成功的所有PDCP PDU的序列号。根据另外一个或多个实施例，所述指示消息携带已发送成 功的PDCP PDU的最小序列号、一个位图以及位图长度指示。该位图是根据已发送成功的PDCP PDU序列号生成的。例如，SeNB从MeNB接收到序列号为1、2、4、5的PDCP PDU，且序列号为1、2、4的PDCP PDU已发送成功，则SeNB向MeNB发送PDCP PDU发送成功的指示消息。根据一个或多个实施例，所述指示消息中携带序列号1、2和4。根据另外一个或多个实施例，所述指示消息携带已发送成功的PDCP PDU最小序列号1、位图长度3、及图8所示位图。图8所示位图中，位图各个位表示对应的PDCP PDU是否被成功发送，各个位对应的PDCP序列号为已发送成功的PDCP PDU最小序列号加上该位在位图中位置所得的值。由于需要指示序列号1(成功发送的PDCP PDU最小序列号)至4(成功发送的PDCP PDU最大序列号)的PDCU PDU，因此该位图长度为4-1＝3。(从1至4共4个PDCP PDU，但是序列号为1的PDCP PDU已经单独指示，不再需要在位图中进行指示)。作为示例，在图8所示的位图中，值为1的位置表示对应的PDCP PDU已发送成功，值为0的位置表示没有收到对应的PDCP PDU。例如，位图从左到右的第1位对应序列号为2的PDCP PDU，该位值为1表示序列号为2的PDCP PDU已发送成功。第2位对应序列号为3的PDCP PDU，由于SeNB并未发送序列号为3的PDCP PDU，因此其值为0。第3位对应序列号为4的PDCP PDU，该位值为1表示序列号为4的PDCP PDU已成功发送。
大多数情况下，从MeNB中按照顺序发送的PDCP PDU总是按照顺序到达SeNB，并由SeNB按照顺序发送。按照图7所述实施例，SeNB仍将频繁的生成指示PDCP PDU发送成功的指示消息，导致Xn接口的信令开销较大。
图9给出了根据本公开的一个或多个实施例的辅基站SeNB向主基站MeNB发送指示PDCP PDU发送成功的指示消息的方法900的流程图。
在步骤S910中，SeNB从MeNB接收到要发送的PDCP PDU。
在步骤S920中，启动一个定时器。
在步骤S930中，SeNB发送至少一个PDCP PDU，并发送成功。
在步骤S940中，判断定时器是否期满。如果定时器期满，则执行步骤S950，否则，结束。
在步骤S950中，向MeNB发送指示PDCP PDU发送成功的指示消息。
根据本实施例，通过增加一个定时器indication_timer控制发送指示PDCP PDU发送成功的指示消息的时间间隔。在定时器期满时才向MeNB发送指示PDCP PDU发送成功的指示消息。根据一个或多个实施，所述指示消息指示所有已发送成功的PDCP PDU。根据另外一个或多个实施，所述指示消息仅指示部分已发送成功的PDCP PDU，所指示的PDCP PDU满足以下条件：来自MeNB的序列号小于所指示的PDCP PDU序列号的PDCP PDU已发送成功。例如，假设SeNB从MeNB接收到序列号为1、3、4、5、7的PDCP PDU，且在成功发送序列号为1、3、4、7的PDCP PDU后indication_timer定时器期满。SeNB可以向MeNB发送指示消息指示已成功发送的所有PDCP PDU，即指示序列号为1、3、4、7已发送成功。SeNB也可以向MeNB发送指示消息指示已成功发送的部分PDCP PDU，即指示序列号为1、3、4已发送成功(由于还存在序列号为5的PDCP PDU还未发送成功)。定时器indication_timer值的设置需要考虑MeNB中发送窗的大小、MeNB中向两个下层实体发送PDCP PDU的速率等因素。
在结合图6描述的实施例中，PDCP接收实体通过维护一个接收窗并通过t-Reordering定时器来辅助PDCP发送实体移动发送窗，即发送后续PDCP PDU。图10是示出了根据本公开的一个或多个实施例的PDCP接收实体处的确认PDCP PDU接收成功的方法1000的流程图。
如图所示，在步骤S1010处，PDCP接收实体维护一个接收窗，所述接收窗的下界指示尚未接收到的PDCP PDU的最小序列号。
在步骤S1020处，接收到至少一个PDCP PDU。
在步骤S1030处，如果接收到的PDCP PDU的序列号大于所述接收窗的下界但序列号落入接收窗内则启动定时器。
在步骤S1040处，如果接收到接收窗的下界对应的PDCP PDU，移动所述接收窗并删除所述定时器。
在步骤S1050处，判断所述定时器期满是否期满。如果是，则在步骤S1060处，移动所述接收窗，并向发送所述PDCP PDU的主基站发送指示消息，以指示所述主基站移动发送窗，其中，所述消息包含尚未接收到的PDCP PDU的所述最小序列号。否则，继续返回步骤S1020等待接收PDCP  PDU。
根据一个或多个实施例，在定时器期满时，将所述接收窗的下界设置为尚未接收到的PDCP PDU的次小序列号。
根据一个或多个实施例，所述定时器是t-Reordering定时器。
图11是示出了根据本公开的一个或多个实施例的另一PDCP发送实体处的发送PDCP PDU的方法1100的另一流程图。
首先，PDCP发送实体维护常量t-Transmittingtimer和变量Next_PDCP_Tx_SN、Max_PDCP_ACK_SN。Next_PDCP_Tx_SN用于指示还未被确认发送成功的PDCP PDU的最小序列号，即为发送窗的下界。Max_PDCP_ACK_SN用于指示当前被确认已发送成功的PDCP PDU的最大序列号。
在步骤S1101中，PDCP发送实体从下层实体接收PDCP PDU发送成功的指示消息并更新Max_PDCP_ACK_SN为已发送成功的PDCP PDU的最大序列号。
在步骤S1102中，PDCP发送实体判断所述指示消息中指示的已成功发送的PDCP PDU最小序列号是否为发送窗下界。如果是，则执行步骤S1103；否则，执行步骤S1111。
在步骤S1103中，PDCP发送实体更新Next_PDCP_Tx_SN为新的尚未被确认发送成功的PDCP PDU的最小序列号。
在步骤S1104中，PDCP发送实体判断已成功发送的PDCP PDU最大序列号(即，变量Max_PDCP_ACK_SN)是否大于Next_PDCP_Tx_SN。如果大于，则执行步骤S1105；否则，执行步骤S1109。
在步骤S1105中，PDCP发送实体判断序列号为Next_PDCP_Tx_SN的PDCP PDU是否通过SeNB发送给UE的PDCP接收实体。如果是，则执行步骤S1106，否则执行步骤S1109。
在步骤S1106中，判断是否有正在运行的定时器。如果有，则执行步骤S1107，否则执行步骤S1108。
在步骤S1107，重启t-Transmitting定时器。
在步骤S1108，启动t-Transmitting定时器。
在步骤S1109，判断是否有正在运行的t-Transmitting定时器。如果有， 则执行步骤S1110，否则该方法结束。
在步骤S1110，删除正在运行的t-Transmitting定时器。
在步骤S1111，判断序列号为Next_PDCP_Tx_SN的PDCP PDU是否被发送给seNB。如果是，则该方法结束。否则，执行步骤S1112。
在步骤S1112中，判断是否有正在运行的t-Transmitting定时器。如果有，则该方法结束，否则执行步骤S1113。
在步骤S1113，启动t-Transmitting定时器。
根据该实施例，通过维护一个变量来实现对是否存在丢包的判断。
与根据本公开的一个或多个实施例的方法相对应地，本公开还提出了相关的PDCP发送实体2000。图12是示出了根据本公开的一个或多个实施例的PDCP发送实体2000的示意结构方框图。
如图所示，该PDCP发送实体2000包括：定时器2010；接收器2020；发送窗移动单元2030；以及定时器控制器2040。
接收器2020被配置为接收PDCP PDU发送成功的指示消息。
发送窗移动单元2030被配置为根据指示消息中指示的已成功发送的PDCP PDU的序列号来移动发送窗。
定时器控制器2040被配置为确定是否存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU，并在确定存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU时启动所述定时器2010。
根据一个或多个实施例，发送窗移动单元2030还被配置为：当定时器2010期满时，移动发送窗。
根据一个或多个实施例，发送窗移动单元2030还被配置为：当定时器2010期满时，将所述发送窗的下界设置为还未被确认发送成功的PDCP PDU的次小序列号。
根据一个或多个实施例，定时器控制器2030还被配置为：判断是否移动了所述发送窗。如果移动了所述发送窗，则在定时器2010没有启动的情况下启动定时器2010，或者在定时器2010已经启动的情况下重启定时器2010；
如果没有移动所述发送窗，则在定时器2010没有启动的情况下启动定时器2010。
根据一个或多个实施例，定时器控制器2030还被配置为：如果确定不存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU，则删除正在运行的定时器2010。
根据一个或多个实施例，定时器控制器2030还被配置为：判断所述发送窗的下界所对应的PDCP PDU是否被发送给辅基站。如果是，则启动定时器；否则，不对定时器进行操作。
根据一个或多个实施例，定时器2010的期满值是根据从所述PDCP实体接收PDCP PDU的PDCP接收实体的t-Reordering定时器设置的。
根据一个或多个实施例，所述指示消息包括成功发送的所有PDCP PDU的序列号。
根据一个或多个实施例，所述指示消息包括：成功发送的PDCU PDU的最小序列号、一个位图以及位图长度指示，所述位图中的各个位表示对应的PDCP PDU是否被成功发送，所述位图中的各个位对应的PDCP PDU的序列号为已发送成功的PDCP PDU最小序列号加上该位在位图中的位置所得的值。
与根据本公开的一个或多个实施例的方法相对应地，本公开还提出了相关的辅基站3000。图13是示出了本公开的一个或多个实施例的辅基站3000的示意结构方框图。
如图所示，该辅基站3000包括：接收器3010以及发送器3030。
接收器3010被配置为从主基站接收要发送的PDCP PDU，每个PDCP PDU均具有序列号。
发送器3030被配置为在成功地发送了至少一个PDCP PDU之后，向主基站发送指示PDCP PDU发送成功的消息，所述消息指示成功发送的PDCP PDU的序列号。
如图13所示，辅基站3000还可包括判断单元3020。
判断单元3020被配置为在成功地发送了至少一个PDCP PDU之后，被配置为判断是否有序列号小于已发送成功的PDCP PDU序列号的PDCP PDU还未发送成功。
发送器3030还被配置为在所述判断单元判断没有序列号小于已发送成功的PDCP PDU序列号的PDCP PDU还未发送成功，则向主基站发送 指示PDCP PDU发送成功的消息。
图13还示出了，辅基站3000可包括定时器3040和定时器控制器3050。定时器控制器3050被配置为在从主基站接收到要发送的PDCP PDU时，启动所述定时器3040。根据一个或多个实施例，发送器3030还被配置为在成功地发送了至少一个PDCP PDU之后，等待所述定时器3040期满，才向主基站发送指示PDCP PDU发送成功的消息。
根据一个或多个实施例，所述消息包括成功发送的所有PDCP PDU的序列号。
根据另外一个或多个实施例，所述消息包括：成功发送的PDCU PDU的最小序列号、一个位图以及位图长度指示，所述位图中的各个位表示对应的PDCP PDU是否被成功发送，所述位图中的各个位对应的PDCP PDU的序列号为已发送成功的PDCP PDU最小序列号加上该位在位图中的位置所得的值。
根据再一个或多个实施例，所述消息仅指示部分已发送成功的PDCP PDU，其中，来自主基站的、序列号小于所指示的部分PDCP PDU的序列号的PDCP PDU均已成功发送。
与根据本公开的一个或多个实施例的方法相对应地，本公开还提出了相关的用户设备4000。图14是示出了本公开的一个或多个实施例的用户设备4000的示意结构方框图。
如图所示，该用户设备4000包括：存储器4010；接收器4020；定时器4030；定时器控制器4040；接收窗移动单元4050；以及发送器4060。
存储器4010被配置为维护一个接收窗，所述接收窗的下界指示尚未接收到的PDCP PDU的最小序列号。
接收器4020被配置为接收至少一个PDCP PDU。
定时器控制器4040被配置为当所述接收器接收到序列号大于所述接收窗的下界但序列号落入接收窗内的PDCP PDU时，启动定时器4030，并且当所述接收器接收到接收窗的下界对应的PDCP PDU时，删除定时器4030。
接收窗移动单元4050被配置为当所述接收器4020接收到接收窗的下界对应的PDCP PDU或者当定时器4030期满时，移动所述接收窗。
发送器4060被配置为当定时器4030期满时，向接收到的PDCP PDU所来自的主基站发送指示消息，以指示所述主基站移动发送窗，其中，所述消息包含尚未接收到的所述至少一个PDCP PDU的最小序列号。
根据一个或多个实施例，接收窗移动单元4050被配置为：当定时器4030期满时，将所述接收窗的下界设置为尚未接收到的PDCP PDU的次小序列号。
与根据本公开的一个或多个实施例的方法相对应地，本公开还提出了相关的PDCP发送实体5000。图15是示出了根据本公开的一个或多个实施例的PDCP发送实体5000的示意结构方框图。
如图所示，该PDCP发送实体5000包括：接收器5010以及发送窗移动单元5020。
接收器5010被配置为从PDCP接收实体接收接收端指示消息，所述接收端指示消息指示所述PDCP接收实体未接收到的PDCP PDU的最小序列号。发送窗移动单元5020被配置为比较PDCP发送实体所维护的发送窗的下界与所述接收端指示消息所指示的PDCP PDU的序列号；如果所述发送窗的下界小于或等于所述接收端指示消息所指示的PDCP PDU的序列号，则将所述发送窗的下界移动至大于所述接收端指示消息中携带的序列号、且尚未被确认的PDCP PDU的序列号中的最小序列号。
根据本公开的一个或多个实施例，通过在PDCP发送实体中设置定时器，即使在Xn接口上发生丢包，仍然可以移动发送窗，因此PDCP Tx仍然可以发送新的数据，不会影响无线链路的传输时延和可靠性。根据本公开的另外一些实施例，通过由DCP接收实体维护一个接收窗且通过t-Reordering定时器来辅助PDCP发送实体移动发送窗，这样即使在Xn接口上发生丢包，仍然可以移动发送窗，而且保持了PDCP发送实体和PDCP接收实体的超帧号同步。
这里所公开的本公开实施例的其他设置包括执行在先概述的方法实施例的步骤和操作的软件程序。更具体地，计算机程序产品是如下的一种实施例：具有计算机可读介质，计算机可读介质上编码有计算机程序逻辑，当在计算设备上执行时，计算机程序逻辑提供相关的操作，从而提供上述技术方案。当在计算***的至少一个处理器上执行时，计算机程序逻辑使 得处理器执行本公开实施例所述的操作(方法)。本公开的这种设置典型地提供为设置或编码在例如光介质(例如CD-ROM)、软盘或硬盘等的计算机可读介质上的软件、代码和/或其他数据结构、或者诸如一个或多个ROM或RAM或PROM芯片上的固件或微代码的其他介质、或专用集成电路(ASIC)、或一个或多个模块中的可下载的软件图像、共享数据库等。软件或固件或这种配置可安装在计算设备上，以使得计算设备中的一个或多个处理器执行本公开实施例所述的技术。结合诸如一组数据通信设备或其他实体中的计算设备进行操作的软件过程也可以提供根据本公开的设备。根据本公开的设备也可以分布在多个数据通信设备上的多个软件过程、或者在一组小型专用计算机上运行的所有软件过程、或者单个计算机上运行的所有软件过程之间。
应该理解，严格地讲，本公开的实施例可以实现为计算机设备上的软件程序、软件和硬件、或者单独的软件和/或单独的电路。
应当注意的是，在以上的描述中，仅以示例的方式，示出了本公开的技术方案，但并不意味着本公开局限于上述步骤和单元结构。在可能的情形下，可以根据需要对步骤和单元结构进行调整和取舍。因此，某些步骤和单元并非实施本公开的总体公开思想所必需的元素。因此，本公开所必需的技术特征仅受限于能够实现本公开的总体公开思想的最低要求，而不受以上具体实例的限制。
尽管以上已经结合本公开的优选实施例示出了本发明，但是本领域的技术人员将会理解，在不脱离本发明的精神和范围的情况下，可以对本发明进行各种修改、替换和改变。因此，本发明不应由上述实施例来限定，而应由所附权利要求及其等价物来限定。

Claims (42)

  1. 一种分组数据汇聚协议(PDCP)发送实体处的发送分组数据汇聚协议协议数据单元(PDCP PDU)的方法，包括：
    在接收到PDCPPDU发送成功的指示消息时：
    根据指示消息中指示的已成功发送的PDCP PDU的序列号来移动发送窗，使得发送窗的下界指示未被确认发送成功的PDCP PDU的最小序列号；
    确定是否存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU：
    如果存在，则启动定时器。
  2. 根据权利要求1所述的方法，还包括：
    当所述定时器期满时，移动所述发送窗。
  3. 根据权利要求2所述的方法，其中，当所述定时器期满时，移动所述发送窗包括：
    将所述发送窗的下界设置为还未被确认发送成功的PDCP PDU的次小序列号；以及
    确定是否存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU：
    如果存在，则启动所述定时器。
  4. 根据权利要求3所述的方法，其中，启动所述定时器还包括：
    判断是否移动了所述发送窗：
    如果移动了所述发送窗，则在所述定时器没有启动的情况下启动所述定时器，或者在所述定时器已经启动的情况下重启所述定时器；
    如果没有移动所述发送窗，则在所述定时器没有启动的情况下启动所述定时器。
  5. 根据权利要求3所述的方法，其中，如果确定不存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU，则删除正在运行的定时器。
  6. 根据权利要求1-5之一所述的方法，在启动所述定时器之前，还包括：
    判断所述发送窗的下界所对应的PDCPPDU是否被发送给辅基站；
    如果是，则启动所述定时器；
    否则，不对所述定时器进行操作。
  7. 根据权利要求1-5之一所述的方法，其中，所述定时器的期满值是根据PDCP接收实体的-t-Reordering定时器设置的。
  8. 根据权利要求1-5之一所述的方法，其中，所述指示消息包括成功发送的所有PDCP PDU的序列号。
  9. 根据权利要求1-5之一所述的方法，其中，所述指示消息包括：成功发送的PDCU PDU的最小序列号、一个位图以及位图长度指示，所述位图中的各个位表示对应的PDCP PDU是否被成功发送，所述位图中的各个位对应的PDCP PDU的序列号为已发送成功的PDCP PDU最小序列号加上该位在位图中的位置所得的值。
  10. 根据权利要求1-5之一所述的方法，其中，根据指示消息中指示的已成功发送的PDCP PDU的序列号来移动发送窗包括：
    维护变量Next_PDCP_Tx_SN和Max_PDCP_ACK_SN，其中Next_PDCP_Tx_SN指示还未被确认发送成功的PDCP PDU的最小序列号，Max_PDCP_ACK_SN指示当前被确认已发送成功的PDCP PDU的最大序列号，所述变量Next_PDCP_Tx_SN是所述发送窗的下界；
    在接收到PDCP PDU发送成功的指示消息时，根据指示消息中指示的已成功发送的PDCP PDU的序列号来更新变量Next_PDCP_Tx_SN和 Max_PDCP_ACK_SN。
  11. 根据权利要求10所述的方法，其中，确定是否存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU包括：
    比较变量Next_PDCP_Tx_SN和变量Max_PDCP_ACK_SN；
    如果变量Max_PDCP_ACK_SN大于变量Next_PDCP_Tx_SN，则确定存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU。
  12. 根据权利要求11所述的方法，其中，当所述定时器期满时，移动所述发送窗包括：
    将变量Next_PDCP_Tx_SN设置为除所述还未被确认发送成功的PDCP PDU的最小序列号外的还未被确认发送成功的PDCP PDU的最小序列号。
  13. 根据权利要求1-5之一所述的方法，其中，所述PDCP发送实体在与至少一个辅基站协作以向用户设备进行发送的主基站处。
  14. 一种分组数据汇聚协议(PDCP)发送实体处的发送分组数据汇聚协议协议数据单元(PDCP PDU)的方法，包括：
    从PDCP接收实体接收接收端指示消息，所述接收端指示消息指示所述PDCP接收实体未接收到的PDCPPDU的最小序列号；
    比较所述发送窗的下界与所述接收端指示消息所指示的PDCP PDU的序列号；以及
    如果所述发送窗的下界小于或等于所述接收端指示消息所指示的PDCP PDU的序列号，则将所述发送窗的下界移动至大于所述接收端指示消息中携带的序列号、且尚未被确认的PDCP PDU的序列号中的最小序列号。
  15. 一种分组数据汇聚协议(PDCP)接收实体处的确认分组数据汇聚协议协议数据单元(PDCP PDU)接收成功的方法，包括：
    维护一个接收窗，所述接收窗的下界指示尚未接收到的PDCP PDU的最小序列号；
    当接收到序列号大于所述接收窗的下界但序列号落入接收窗内的PDCP PDU时，启动定时器；
    当接收到接收窗下界对应的PDCP PDU时，移动所述接收窗并删除所述定时器；以及
    当所述定时器期满时，移动所述接收窗，并向发送所述PDCP PDU的主基站发送指示消息，以指示所述主基站移动发送窗，其中，所述消息包含尚未接收到的PDCP PDU的所述最小序列号。
  16. 根据权利要求15所述的方法，其中，当所述定时器期满时，移动所述接收窗包括：
    将所述接收窗的下界设置为尚未接收到的PDCP PDU的次小序列号。
  17. 根据权利要求16所述的方法，其中，所述定时器是t-Reordering定时器。
  18. 根据权利要求17所述的方法，其中，所述PDCP接收实体在从所述主基站接收服务的用户设备处。
  19. 一种辅基站处的确认分组数据汇聚协议协议数据单元(PDCP PDU)发送成功的方法，包括：
    从主基站接收要发送的PDCP PDU，每个PDCP PDU均具有序列号；以及
    在成功地发送了至少一个PDCP PDU之后，向主基站发送指示PDCP PDU发送成功的消息，所述消息指示被成功发送的PDCP PDU的序列号。
  20. 根据权利要求19所述的方法，在向主基站发送指示PDCP PDU发送成功的消息之前，还包括：
    判断是否有序列号小于已发送成功的PDCP PDU序列号的PDCP PDU 还未发送成功；
    如果没有，则向主基站发送指示PDCP PDU发送成功的消息，所述消息指示被成功发送的PDCP PDU的序列号。
  21. 根据权利要求19所述的方法，还包括：
    在从主基站接收到要发送的PDCP PDU时，启动定时器；以及
    在成功地发送了至少一个PDCP PDU之后，等待所述定时器期满，才向主基站发送指示PDCP PDU发送成功的消息。
  22. 根据权利要求19-21之一所述的方法，其中，所述消息包括成功发送的所有PDCP PDU的序列号。
  23. 根据权利要求19-21之一所述的方法，其中，所述消息包括：成功发送的PDCU PDU的最小序列号、一个位图以及位图长度指示，所述位图中的各个位表示对应的PDCP PDU是否被成功发送，所述位图中的各个位对应的PDCP PDU的序列号为已发送成功的PDCP PDU最小序列号加上该位在位图中的位置所得的值。
  24. 根据权利要求19-21之一所述的方法，其中，所述消息仅指示部分已发送成功的PDCP PDU，其中，来自主基站的、序列号小于所指示的部分PDCP PDU的序列号的PDCP PDU均已成功发送。
  25. 一种分组数据汇聚协议PDCP发送实体，包括：
    定时器；
    接收器，被配置为接收分组数据汇聚协议协议数据单元(PDCP PDU)发送成功的指示消息；
    发送窗移动单元，被配置为根据指示消息中指示的已成功发送的PDCP PDU的序列号来移动发送窗；以及
    定时器控制器，被配置为确定是否存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU，并在确定存在被确认已成功发送的、 序列号大于所述发送窗的下界的PDCP PDU时启动所述定时器。
  26. 根据权利要求25所述的PDCP发送实体，其中，所述发送窗移动单元还被配置为：当所述定时器期满时，移动所述发送窗。
  27. 根据权利要求26所述的PDCP发送实体，其中，所述发送窗移动单元还被配置为：当所述定时器期满时，将所述发送窗的下界设置为还未被确认发送成功的PDCP PDU的次小序列号。
  28. 根据权利要求26所述的PDCP发送实体，其中，所述定时器控制器还被配置为：
    判断是否移动了所述发送窗：
    如果移动了所述发送窗，则在所述定时器没有启动的情况下启动所述定时器，或者在所述定时器已经启动的情况下重启所述定时器；
    如果没有移动所述发送窗，则在所述定时器没有启动的情况下启动所述定时器。
  29. 根据权利要求26所述的PDCP发送实体，其中，所述定时器控制器还被配置为：
    如果确定不存在被确认已成功发送的、序列号大于所述发送窗的下界的PDCP PDU，则删除正在运行的定时器。
  30. 根据权利要求26所述的PDCP发送实体，其中，所述定时器控制器还被配置为：
    判断所述发送窗的下界所对应的PDCP PDU是否被发送给辅基站；
    如果是，则启动所述定时器；
    否则，不对所述定时器进行操作。
  31. 根据权利要求26所述的PDCP发送实体，其中，所述定时器的期满值是根据从所述PDCP发送实体接收PDCP PDU的PDCP接收实体的 t-Reordering定时器设置的。
  32. 根据权利要求26所述的PDCP发送实体，其中，所述指示消息包括成功发送的所有PDCP PDU的序列号。
  33. 根据权利要求26所述的PDCP发送实体，其中，所述指示消息包括：成功发送的PDCU PDU的最小序列号、一个位图以及位图长度指示，所述位图中的各个位表示对应的PDCP PDU是否被成功发送，所述位图中的各个位对应的PDCP PDU的序列号为已发送成功的PDCP PDU最小序列号加上该位在位图中的位置所得的值。
  34. 一种分组数据汇聚协议PDCP发送实体，包括：
    接收器，被配置为从PDCP接收实体接收接收端指示消息，所述接收端指示消息指示所述PDCP接收实体未接收到的分组数据汇聚协议协议数据单元(PDCP PDU)的最小序列号；以及
    发送窗移动单元，被配置为比较所述PDCP发送实体所维护的发送窗的下界与所述接收端指示消息所指示的PDCP PDU的序列号；如果所述发送窗的下界小于或等于所述接收端指示消息所指示的PDCP PDU的序列号，则将所述发送窗的下界移动至大于所述接收端指示消息中携带的序列号、且尚未被确认的PDCP PDU的序列号中的最小序列号。
  35. 一种用户设备，包括：
    存储器，被配置为维护一个接收窗，所述接收窗的下界指示尚未接收到的分组数据汇聚协议协议数据单元(PDCP PDU)的最小序列号；
    接收器，被配置为接收至少一个PDCP PDU；
    定时器；
    定时器控制器，被配置为当所述接收器接收到序列号大于所述接收窗的下界但序列号落入接收窗内的PDCP PDU时，启动所述定时器，并且当所述接收器接收到接收窗下界对应的PDCP PDU时，删除所述定时器；
    接收窗移动单元，被配置为当所述接收器接收到接收窗下界对应的PDCP PDU或者当所述定时器期满时，移动所述接收窗；以及
    发送器，被配置为当所述定时器期满时，向接收到的PDCP PDU所来自的主基站发送指示消息，以指示所述主基站移动发送窗，其中，所述消息包含尚未接收到的所述至少一个PDCP PDU的最小序列号。
  36. 根据权利要求35所述的用户设备，其中，所述接收窗移动单元被配置为：当所述定时器期满时，将所述接收窗的下界设置为尚未接收到的PDCP PDU的次小序列号。
  37. 一种与主基站协作的辅基站，包括：
    接收器，被配置为从主基站接收要发送的分组数据汇聚协议协议数据单元(PDCP PDU)，每个PDCP PDU均具有序列号；以及
    发送器，被配置为在成功地发送了至少一个PDCP PDU之后，向主基站发送指示PDCP PDU发送成功的消息，所述消息指示成功发送的PDCP PDU的序列号。
  38. 根据权利要求37所述的辅基站，还包括：
    判断单元，被配置为判断是否有序列号小于已发送成功的PDCP PDU序列号的PDCP PDU还未发送成功；以及
    所述发送器被配置为：在所述判断单元判断没有序列号小于已发送成功的PDCP PDU序列号的PDCP PDU还未发送成功，则向主基站发送指示PDCP PDU发送成功的消息。
  39. 根据权利要求37所述的辅基站，还包括：
    定时器；以及
    定时器控制器，被配置为在从主基站接收到要发送的PDCP PDU时，启动所述定时器；
    所述发送器还被配置为：在成功地发送了至少一个PDCP PDU之后，等待所述定时器期满，才向主基站发送指示PDCP PDU发送成功的消息。
  40. 根据权利要求37-39之一所述的辅基站，其中，所述消息包括成功 发送的所有PDCP PDU的序列号。
  41. 根据权利要求37-39之一所述的辅基站，其中，所述消息包括：成功发送的PDCU PDU的最小序列号、一个位图以及位图长度指示，所述位图中的各个位表示对应的PDCP PDU是否被成功发送，所述位图中的各个位对应的PDCP PDU的序列号为已发送成功的PDCP PDU最小序列号加上该位在位图中的位置所得的值。
  42. 根据权利要求37-39之一所述的辅基站，其中，所述消息仅指示部分已发送成功的PDCP PDU，其中，来自主基站的、序列号小于所指示的部分PDCP PDU的序列号的PDCP PDU均已成功发送。
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