CN110999162B

CN110999162B - Method and apparatus for transmitting and receiving duplicate packets in a mobile communication system

Info

Publication number: CN110999162B
Application number: CN201880053169.XA
Authority: CN
Inventors: 金东建
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2017-08-16
Filing date: 2018-08-16
Publication date: 2023-06-02
Anticipated expiration: 2038-08-16
Also published as: KR20190019000A; KR102554052B1; CN110999162A

Abstract

A communication method and system are provided for fusing a fifth generation (5G) communication system supporting higher data rates than a fourth generation (4G) system with techniques for internet of things (IoT). The method includes smart services based on 5G communication technology and IoT-related technology, such as smart home, smart building, smart city, smart car, networking car, health care, digital education, smart retail, security and security services. The present disclosure provides a packet processing method of a transmitter, the method comprising: transmitting Radio Link Control (RLC) Service Data Units (SDUs) to a receiver; receiving a first message including information on whether the RLC SDU is successfully transmitted from a receiver; and when the receiver receives the RLC SDU, transmitting a first indicator indicating successful transmission of the RLC SDU from the RLC entity of the transmitter to a Packet Data Convergence Protocol (PDCP) entity of the transmitter.

Description

Method and apparatus for transmitting and receiving duplicate packets in a mobile communication system

Technical Field

The present disclosure relates to a method of a transmitting apparatus for efficiently transmitting duplicate packets in a next generation mobile communication system and a method of a receiving apparatus for efficiently receiving duplicate packets in a next generation mobile communication system.

Background

In order to meet the increasing demand for wireless data traffic since the deployment of fourth generation (4G) communication systems, efforts have been made to develop improved fifth generation (5G) or front 5G (pre-5G) communication systems. Therefore, the 5G or front 5G communication system is also referred to as a "super 4G network" or a "LTE-after-system". Consider implementing a 5G communication system in a higher frequency (mmWave) band (e.g., 60GHz band) to achieve higher data rates. In order to reduce propagation loss of radio waves and increase transmission distance, in a 5G communication system, there is discussed: beamforming, massive multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna techniques. In addition, in the 5G communication system, development for system network improvement based on the following is underway: advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, cooperative communications, coordinated multipoint (CoMP), receiving end interference cancellation, and the like. In 5G systems, we have developed: hybrid FSK and QAM modulation (FQAM) and Sliding Window Superposition Coding (SWSC) as Advanced Code Modulation (ACM); and Filter Bank Multicarrier (FBMC), non-orthogonal multiple access (NOMA), and Sparse Code Multiple Access (SCMA) as advanced access technologies.

The internet, which is a human-centric connectivity network in which human generation and consumption information is now evolving towards the internet of things (IoT) in which distributed entities exchange and process information without human intervention. Internet of things (IoE) has emerged as a combination of IoT technology and Big Data Processing Technology (BDPT) through a connection with a cloud server. Because technical elements such as "sensing technology", "wired/wireless communication and network infrastructure", "service interface technology", and "security technology" have been required for IoT implementations, sensor networks, machine-to-machine (M2M) communications, machine Type Communications (MTC), etc. have recently been studied. Such IoT environments may provide intelligent internet technology services that create new value for human life by collecting and analyzing data generated in networked things (connected technologies). With the convergence and combination of existing Information Technology (IT) with various industries, ioT can be applied to a variety of fields, including: smart homes, smart buildings, smart cities, smart or networked cars (connected cars), smart grids, health care, smart appliances, and advanced medical services.

In keeping with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, techniques such as sensor networks, MTC, and M2M may be implemented by beamforming, MIMO, and array antennas. Applications of the cloud radio access network (cloud RAN) as BDPT as described above may also be considered as examples of convergence between 5G technology and IoT technology.

The above information is presented as background information only to aid in the understanding of the present disclosure. No determination is made nor is any assertion made as to whether any of the above may be applicable to the prior art with respect to the present disclosure.

Disclosure of Invention

Technical problem

Aspects of the present disclosure will solve at least the problems and/or disadvantages described above and will provide at least the advantages described below. Accordingly, an aspect of the present disclosure is to provide an apparatus and method for a next generation mobile communication system for transmitting the same data through different independent paths using carrier aggregation or dual connectivity in order to increase reliability and reduce transmission delay. When each Radio Link Control (RLC) entity supporting packet repetition (packet duplication) operates in RLC Acknowledged Mode (AM), each RLC entity may perform an independent ARQ function and thus may request unnecessary retransmissions. That is, when data successfully transmitted via the first link is lost in the second link, a receiving RLC entity corresponding to the second link requests retransmission of the lost data, resulting in transmission delay and unnecessary retransmission, thereby wasting transmission resources.

Solution scheme

According to one aspect of the present disclosure, a method and apparatus are provided. The apparatus includes a method for reducing unnecessary retransmissions, waste of transmission resources, and transmission delay.

According to an aspect of the present disclosure, a packet processing method of a transmitter is provided. The method comprises the following steps: transmitting RLC Service Data Units (SDUs) to a receiver via a transmitter; receiving a first message including information on whether the RLC SDU is successfully transmitted from a receiver; and when the receiver receives the RLC SDU, transmitting a first indicator indicating successful transmission of the RLC SDU from the RLC entity of the transmitter to a Packet Data Convergence Protocol (PDCP) entity of the transmitter via the transmitter.

According to an aspect of the present disclosure, an apparatus for a conveyor is provided. The apparatus includes a transceiver; and a controller configured to: the control transceiver transmits the RLC SDU to the receiver, receives a first message including information about whether the RLC SDU was successfully transmitted from the receiver, and transmits a first indicator indicating successful transmission of the RLC SDU from the RLC entity of the transmitter to the PDCP entity when the receiver receives the RLC SDU.

Advantageous effects

The present disclosure proposes an operation for effectively using a transmitting apparatus and a receiving apparatus adapted for packet repetition of a next generation mobile communication system, thereby reducing unnecessary retransmission, waste of transmission resources, and transmission delay.

Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure.

Drawings

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

fig. 1A illustrates a structure of an LTE system according to an embodiment of the present disclosure;

fig. 1B illustrates a wireless protocol structure of an LTE system according to an embodiment of the present disclosure;

fig. 1C illustrates a structure of a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 1D illustrates a radio protocol structure of a next-generation mobile communication system according to an embodiment of the present disclosure;

fig. 1E illustrates a process of processing data in each layer in a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 1F illustrates a window function operating according to a Packet Data Convergence Protocol (PDCP) Sequence Number (SN) in a PDCP layer of a next generation mobile communication system according to an embodiment of the present disclosure;

Fig. 1G illustrates a window function operating according to an RLC SN in a Radio Link Control (RLC) layer of a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 1H illustrates packet repetition in which a PDCP layer transmits repeated packets in a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 1I illustrates a specific example of packet repetition for a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 1J illustrates a problem that occurs when different RLC layers independently perform an ARQ function in packet repetition according to an embodiment of the present disclosure;

fig. 1K illustrates a mapping table set forth in a first embodiment showing the operation of an efficient transmitting RLC layer entity in packet repetition according to an embodiment of the present disclosure;

fig. 1L illustrates a method for constructing data to be transmitted when a second (or first) transmitting RLC layer retransmits data identified as successfully delivered in the first (or second) transmitting RLC layer, according to an embodiment of the present disclosure;

fig. 1M illustrates a mapping table applied in a second embodiment of an efficient receiving RLC layer entity of the present disclosure for preventing unnecessary retransmission and waste of transmission resources and reducing transmission delay in packet repetition of a next generation mobile communication system according to an embodiment;

Fig. 1N illustrates an operation of transmitting an RLC layer entity according to an embodiment of the present disclosure;

fig. 1O illustrates operations of a receiving RLC layer entity according to an embodiment of the present disclosure;

fig. 1P illustrates a configuration of a UE according to an embodiment of the present disclosure; and

fig. 1Q illustrates a configuration of a base station in a wireless communication system according to an embodiment of the present disclosure.

Like reference numerals are used to denote like elements throughout the figures.

Detailed Description

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of the various embodiments of the disclosure defined by the claims and their equivalents. It includes various specific details to aid in understanding, but these are to be considered exemplary only. Accordingly, one of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to written meanings, but are used only by the inventors to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following descriptions of the various embodiments of the present disclosure are provided for illustration only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.

It is to be understood that the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more such surfaces.

In the present disclosure, a detailed description of related known configurations or functions incorporated herein will be omitted when it may be determined that the detailed description thereof may unnecessarily obscure the subject matter of the present disclosure. Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

As used in the following description, terms for identifying an access node, terms referring to network entities, terms referring to messages, terms referring to interfaces between network objects, and terms referring to various identification information are shown for ease of explanation. Accordingly, the present disclosure is not limited to the following terms, and other terms referring to objects having an equivalent technical meaning may be used.

For ease of explanation, the present disclosure uses terms and words defined in the third generation partnership project long term evolution (3 GPP LTE) standard. However, the present disclosure is not limited by these terms and words, and may be equally applied to systems according to other standards. In this disclosure, for ease of explanation, enbs may be used interchangeably with gNB. That is, an eNB shown as a base station may refer to a gNB.

Fig. 1A illustrates a structure of an LTE system according to the present disclosure.

Referring to fig. 1a, a radio access network of an lte system includes: an evolved node B (eNB, node B or base station) 1a-05, 1a-10, 1a-15 or 1a-20, a Mobility Management Entity (MME) 1a-25 and a serving gateway (S-GW) 1a-30. A User Equipment (UE) or terminal 1a-35 accesses an external network through enbs 1a-05 to 1a-20 and S-GW 1a-30.

In fig. 1A, enbs 1A-05 to 1A-20 correspond to existing node bs of a UMTS system. The eNB connects to the UEs 1a-35 over a radio channel and plays a more complex role (role) than the role of the existing node B. In the LTE system, since all user traffic (including real-time services such as voice over internet protocol (VoIP) services) is provided through a shared channel, a device that collects state information such as a buffer status of a UE, an available transmission power status, and a channel status and performs scheduling is required. The eNBs 1a-05 to 1a-20 are responsible for these functions. One eNB typically controls multiple cells. For example, in order to achieve a transmission speed of 100Mbps, the LTE system uses Orthogonal Frequency Division Multiplexing (OFDM) as a radio access technology, for example, at a bandwidth of 20 MHz. In addition, the LTE system applies Adaptive Modulation and Coding (AMC), which determines a modulation scheme and a channel coding rate according to the channel state of the UE. The S-GW 1a-30 is a device that provides data bearers and generates or removes data bearers under control of the MME 1 a-25. The MME is the following: the apparatus performs not only a mobility management function for a UE but also various control functions, and is connected to a plurality of base stations.

Fig. 1B illustrates a wireless protocol structure of an LTE system according to the present disclosure.

Referring to fig. 1b, wireless protocols of the lte system include Packet Data Convergence Protocols (PDCP) 1b-05 and 1b-40, radio Link Control (RLC) 1b-10 and 1b-35, and Medium Access Control (MAC) 1b-15 and 1b-30 at the UE and the eNB, respectively.

PDCP 1b-05 and 1b-40 are responsible for IP header compression/decompression, etc. The main functions of PDCP are summarized as follows:

header compression and decompression (ROHC only)

Delivery of user data

In-order delivery of higher layer PDUs in PDCP re-establishment procedure for RLC AM

For split bearers in DC (supporting RLC AM only), PDCP PDU routing for delivery and PDCP PDU reordering for reception

Duplicate detection of lower layer SDUs in PDCP re-establishment procedure for RLC AM

Retransmission of PDCP SDUs in handover for split bearers in DC and retransmission of PDCP PDUs in PDCP data recovery for RLC AM

-encryption and decryption

Timer based SDU discard in uplink

The RLC 1b-10 and 1b-35 reconstruct PDCP Packet Data Units (PDUs) to an appropriate size and perform ARQ operations. The main functions of RLC are summarized as follows:

delivery of higher layer PDUs

Error correction by ARQ (for AM data transfer only)

Concatenation, segmentation and reassembly of RLC SDUs (for UM and AM data transfer only)

Re-segmentation of RLC data PDU (for AM data transfer only)

Reordering of RLC data PDUs (for UM and AM data transfer only)

Duplicate detection (for UM and AM data delivery only)

Protocol error detection (for AM data transfer only)

RLC SDU discard (for UM and AM data transfer only)

RLC re-establishment

The MACs 1b-15 and 1b-30 are connected to a plurality of RLC layer entities configured in one UE, multiplex RLC PDUs into MAC PDUs and demultiplex MAC PDUs into RLC PDUs. The main functions of the MAC are summarized as follows:

mapping between logical channels and transport channels

Multiplexing/de-multiplexing of MAC SDUs belonging to one or different logical channels into/from Transport Blocks (TBs) delivered to/from a physical layer on transport channels

Scheduling information reporting

Error correction by HARQ

Priority handling between logical channels of a UE

Priority handling between UEs by means of dynamic scheduling

MBMS service identity

Transport format selection

-filling

The Physical (PHY) layers 1b-20 and 1b-25 perform channel coding and modulation of higher layer data and convert the data into OFDM symbols to transmit the OFDM symbols via a wireless channel; or demodulates OFDM symbols received via a wireless channel and performs channel decoding of the OFDM symbols to deliver the OFDM symbols to a higher layer.

Fig. 1C illustrates a structure of a next-generation mobile communication system according to the present disclosure.

Referring to fig. 1C, a radio access network (hereinafter, referred to as NR or 5G) of a next generation mobile communication system includes a new radio node B (NR gNB) or NR base station 1C-10 and a new radio core network (NR CN) 1C-05. The new radio user equipment (NR UE or terminal 1 c-15) accesses the external network through NR gNB 1c-10 and NR CN 1c-05.

In fig. 1C, NR gNB 1C-10 corresponds to an evolved node B (eNB) of an existing LTE system. The NR gNB is connected to NR UE 1c-15 through a wireless channel and can provide more advanced services than those of the existing eNB. In the next generation mobile communication system, since all user traffic is serviced through a shared channel, a device that collects state information such as a buffer status of a UE, an available transmission power status, and a channel status and performs scheduling is required. NR gNB 1c-10 is responsible for these functions. One NR gNB typically controls multiple cells. In order to achieve ultra-high speed data transmission compared to current LTE, NR may have a bandwidth greater than the existing maximum bandwidth, and a beamforming technique may be employed as a radio access technique in addition to OFDM. Further, the NR applies AMC, which determines a modulation scheme and a channel coding rate according to the channel state of the UE.

The NR CN 1c-05 performs the functions of mobility support, bearer setup, and QoS setup. The NR CN is the following: the apparatus performs not only a mobility management function for a UE but also various control functions, and is connected to a plurality of base stations. The next generation mobile communication system may also interwork with existing LTE systems, in which case the NR CN is connected to the MME 1c-25 through a network interface. The MME is connected to the eNBs 1c-30 as existing base stations.

Fig. 1D illustrates a radio protocol structure of a next-generation mobile communication system according to the present disclosure.

Referring to fig. 1D, the radio protocol of the next generation mobile communication system includes NR PDCP 1D-05 and 1D-40, NR RLC 1D-10 and 1D-35, and NR MAC 1D-15 and 1D-, 1D-30 at the UE and the NR base station, respectively.

The main functions of NR PDCP 1d-05 and 1d-40 may include some of the following functions:

header compression and decompression (ROHC only)

Delivery of user data

In-order delivery of higher layer PDUs

Out-of-order delivery of higher layer PDUs

Reordering of PDCP PDUs for reception

Duplicate detection of lower layer SDUs

Retransmission of PDCP SDUs

-encryption and decryption

-timer based SDU discard in uplink.

Among the above functions, the reordering function of the NR PDCP entity refers to a function of reordering PDCP PDUs received in a lower layer in order based on a PDCP Sequence Number (SN), and may include a function of transferring data to a higher layer in reordered order or a function of immediately transferring data regardless of the order. In addition, the reordering function of the NR PDCP entity may include a function of recording lost PDCP PDUs via reordering, may include a function of reporting a status of the lost PDCP PDUs to a transmitter, and may include a function of requesting retransmission of the lost PDCP PDUs. The main functions of NR RLCs 1d-10 and 1d-35 may include some of the following functions:

Delivery of higher layer PDUs

In-order delivery of higher layer PDUs

Out-of-order delivery of higher layer PDUs

Error correction by ARQ

Concatenation, segmentation and reassembly of RLC SDUs

Re-segmentation of RLC data PDUs

Reordering of RLC data PDUs

-repeated detection

Protocol error detection

RLC SDU discard

RLC re-establishment

Among the above functions, the in-order delivery function of the NR RLC entity refers to a function of sequentially delivering RLC SDUs received from a lower layer to a higher layer, and may include a function of reassembling and delivering a plurality of RLC SDUs when one original RLC SDU is divided into a plurality of RLC SDUs to be received. In addition, the in-order delivery function of the NR RLC entity may include a function of reordering received RLC PDUs based on RLC SNs or PDCP SNs, and may include a function of recording lost RLC PDUs via reordering. In addition, the in-order delivery function of the NR RLC entity may include a function of reporting a status of the missing RLC PDU to the transmitter, may include a function of requesting retransmission of the missing RLC PDU, and may include sequentially delivering RLC SDUs only before the missing RLC SDU to a higher layer if there is the missing RLC SDU. The in-order delivery function of the NR RLC entity may include the following functions: the function of sequentially delivering all RLC SDUs received before the timer starts to a higher layer when the timer expires, although there are missing RLC SDUs; or may include the following functions: the functionality of all RLC SDUs received so far is delivered to the higher layer in sequence when the timer expires, despite the presence of missing RLC SDUs.

The NR RLC entity may process RLC PDUs in the reception order (arrival order regardless of SN order) and may deliver RLC PDUs to the PDCP entity in an out-of-order manner. For a segment, the NR RLC entity may receive the segment stored in the buffer or to be received later, may reconstruct the segment into one complete RLC PDU, may process the RLC PDU, and may deliver the RLC PDU to the PDCP entity. The NR RLC layer may not include a concatenation function, and the concatenation function may be performed in the NR MAC layer or may be replaced with a multiplexing function of the NR MAC layer.

The out-of-order delivery function of the NR RLC entity refers to a function of delivering RLC SDUs received from a lower layer directly to a higher layer regardless of order, and may include a function of reassembling and delivering a plurality of RLC SDUs when one original RLC SDU is divided into a plurality of RLC SDUs to be received. In addition, the out-of-order delivery function of the NR RLC entity may include a function of recording missing RLC PDUs by storing and reordering RLC SNs or PDCP SNs of the received RLC PDUs.

NR MACs 1d-15 and 1d-30 may be connected to a plurality of NR RLC layer entities configured in one UE. The primary functions of NR MAC may include some of the following functions:

Mapping between logical channels and transport channels

Multiplexing/demultiplexing of MAC SDUs

Scheduling information reporting

Error correction by HARQ

Priority handling between logical channels of a UE

Priority handling between UEs by means of dynamic scheduling

MBMS service identity

Transport format selection

-filling

The NR PHY layers 1d-20 and 1d-25 may perform channel coding and modulation of higher layer data and convert the data into OFDM symbols to transmit the OFDM symbols via a wireless channel; or demodulates OFDM symbols received via a wireless channel and performs channel decoding of the OFDM symbols to deliver the OFDM symbols to a higher layer.

In the present disclosure, the transmitting apparatus may be a base station or a UE, and the receiving apparatus may be a base station or a UE. The present disclosure may include the following two cases: a case where the transmitting apparatus is a base station and the receiving apparatus is a UE (downlink data transmission scenario), and a case where the transmitting apparatus is a UE and the receiving apparatus is a base station (uplink data transmission scenario). The transmitting means may refer to a base station or UE and the receiving means may refer to a base station or UE.

Fig. 1E illustrates a process of processing data in each layer in a next generation mobile communication system according to an embodiment of the present disclosure.

Referring to fig. 1E, when an IP packet arrives at a PDCP layer entity, the PDCP layer may perform operations according to the functions of the PDCP layer described in fig. 1D. The PDCP layer may construct PDCP PDUs 1e-05 having PDCP headers and data and may deliver the PDCP PDUs to a lower layer.

The RLC layer, which is a lower layer, may recognize the entire PDCP PDU 1e-05 received from the PDCP layer as one data, and may perform operations according to the functions of the RLC layer described in fig. 1D. The RLC layer forms RLC PDUs 1e-10 by constructing RLC headers and delivers the RLC PDUs to lower layers.

Upon receiving RLC PDUs 1e-10 from the RLC layer, a MAC layer entity as a lower layer may recognize the entire RLC PDU as data and may perform the functions of the MAC layer entity described in fig. 1D. The MAC layer entity completes MAC PDU 1e-15 by constructing a MAC subheader, delivers the MAC PDU to a lower layer, and transfers the MAC PDU through the PHY layer.

When the receiving MAC layer entity of fig. 1E receives the MAC PDUs 1E-20 from the lower layer, the MAC layer entity reads the contents of the MAC header, considers the remaining data as data, and delivers the considered data to the RLC layer, which is the higher layer.

Upon receipt of the RLC PDU 1e-25, the RLC layer reads only RLC headers corresponding to the RLC layer, considers remaining data as data, and delivers the considered data to a higher layer.

Also, when receiving the PDCP PDU 1e-30, the PDCP layer reads only the PDCP header, performs an operation corresponding to the PDCP layer entity, removes the PDCP header from the PDCP PDU 1e-30, and delivers the remaining data to the higher layer.

As described above, each layer of the next generation mobile communication system may read only a header corresponding to each layer, and may not read a header or data of a different layer. Thus, the information is managed and processed independently.

Fig. 1F illustrates a window function operating according to PDCP SNs in a PDCP layer of a next generation mobile communication system according to an embodiment of the present disclosure.

Referring to fig. 1F, the transmitting PDCP entity 1F-05 and the receiving PDCP entity 1F-10 may perform a window operation according to PDCP SNs in PDCP headers. The transmitting PDCP entity may transmit each packet by assigning a PDCP SN to the packet, and transmit the packet to which the PDCP SN is assigned to the receiver via the RLC layer, the MAC layer, and the PHY layer. Upon receiving the transmitted packet, the receiving PDCP layer may read the PDCP header, may identify a PDCP SN, and may perform a windowing operation according to the PDCP SN.

The size of the window may be half the size of PDCP SNs used in the transmitting PDCP entity and the receiving PDCP entity. For example, when the length of the PDCP SN is 18 bits, the size of the window may be 2 (18-1) =2≡17, and the window lower edge 1f-20 is pushed and moved depending on the received PDCP SN. When the window lower edge moves, the corresponding window size is pushed and thus the window upper edge 1f-25 also moves naturally. The PDCP SN may start from zero. The PDCP SNs may be numbers ranging from 0 to 2-17-1.

For example, it is assumed that the transmitting PDCP entity transmits data having

PDCP SNs

0, 1, 2, and 3, and the data having PDCP SN 2 is lost during transmission (1 f-15).

The receiving PDCP entity has successfully received 0 and 1 in the receive window and thus can move the window lower edge 1f-20 to 2. Since data having SN 3 has been received, the receiving PDCP entity can recognize data loss having SN 2 and operate a timer. The timer indicates how long the receiving PDCP entity will wait for lost data corresponding to SN 2. The timer stops when the lost packet arrives within the time the timer is driven. When the timer is reset, the window moves to 4. However, when the lost packet does not arrive until the timer expires and the timer expires (1 f-30), the receiving PDCP entity does not wait for the lost data corresponding to SN 2 any more, moves the window lower edge to 4 and prepares to receive new data.

Therefore, in the PDCP layer, when the PDCP SN is lost, a transmission delay equal to a timer value occurs.

Fig. 1G illustrates a window function operating according to an RLC SN in an RLC layer of a next generation mobile communication system according to an embodiment of the present disclosure.

Referring to fig. 1G, the transmitting RLC entity 1G-05 and the receiving RLC entity 1G-10 may perform a window operation according to RLC SN in an RLC header. The RLC SN is managed separately from the PDCP SN in the PDCP header in fig. 1F, and is included in the RLC header for transmitting and receiving RLC entity operation windows.

The transmitting RLC entity may transmit each packet by assigning an RLC SN to the packet, and the packet assigned the RLC SN is transmitted to the receiver via the RLC layer, MAC layer, and PHY layer. Upon receiving the transmitted packet, the receiving RLC layer may read the RLC header, may identify the RLC SN, and may perform a window operation according to the RLC SN.

The size of the window may be half the size of the RLC SN used in the transmitting RLC entity and the receiving RLC entity. For example, when the length of the RLC SN is 18 bits, the size of the window may be 2 (18-1) =2≡17, and depending on the RLC SN received, the window lower edge 1g-20 is pushed and moved. When the window lower edge moves, the corresponding window size is pushed and thus the window upper edge 1g-25 also moves naturally. The RLC SN may start from zero. The RLC SNs may be numbers ranging from 0 to 2≡17-1.

For example, assume that the transmitting RLC entity transmits data with

RLC SN

0, 1, 2, and 3, and data with RLC SN 2 is lost during transmission (1 g-15).

The receiving RLC entity has successfully received 0 and 1 in the receiving window and can therefore move the window lower edge 1g-20 to 2. Since data having SN 3 has been received, the receiving PDCP entity can recognize data loss having SN 2 and operate a timer. The timer indicates how long the receiving PDCP entity will wait for lost data corresponding to SN 2. The timer stops when the lost packet arrives within the time the timer is driven. When the timer is reset, the window moves to 4. However, when the lost packet does not arrive until the timer expires and the timer expires (1 g-30), the receiving RLC entity configures an RLC status report for the lost data corresponding to SN 2 and transmits the RLC status report to the transmitting RLC entity. The RLC status report may include a request (1 g-35) for retransmission of lost data corresponding to RLC SN 2. In this case, the receiving RLC entity may not move the window lower edge (window stall) until data corresponding to RLC SN 2 is received. The window may be moved only when the transmitting RLC entity retransmits the lost packet and the receiver receives the lost packet. Until the lost packet arrives, the transmitter may perform a retransmission (1 g-40) and the receiver may also request a retransmission. When the number of retransmissions exceeds a predetermined number, the transmitting and receiving RLC entities may release the connection and may perform an RLC entity re-establishment procedure. When the missing data corresponding to RLC SN 2 is successfully received, the receiving RLC entity may move the window lower edge to 4 (1 g-45).

Therefore, in the RLC layer, when RLC SN is lost, transmission delay occurs until a lost packet arrives, and serious transmission delay occurs. As described above, the RLC layer ensures error-free and loss-free transmission.

Fig. 1H illustrates packet repetition in which a PDCP layer transmits repeated packets in a next generation mobile communication system according to an embodiment of the present disclosure.

Referring to fig. 1H, a transmitting apparatus (UE or base station) may construct a header of each layer in each layer for data received in PDCH layer 1H-05, may process the data, and may transmit the data to a lower layer, as shown in fig. 1E. The transmitting device may use carrier aggregation 1h-10 or dual connectivity 1h-15. When the transmitting device uses carrier aggregation or dual connectivity, the transmitting device may activate packet repetition for 1h-20.

When packet repetition is activated, the transmitting apparatus establishes one or more transmitting RLC entities 1h-35 and 1h-50 connected to one transmitting PDCP layer, and the PDCH layer 1h-05 delivers repeated data corresponding to one PDCP SN to the two transmitting RLC entities 1h-30, 1h-35, 1h-45 and 1h-50. The two transmitting RLC entities may process each of the duplicate packets received from the PDCP layer entity and may transmit the packets. When carrier aggregation 1h-10 is used, the transmitting MAC layer entity 1h-40 transmits duplicate packets received from different RLC layer entities 1h-30 and 1h-35 via different frequencies. When dual connectivity 1h-15 is used, transmitting MAC layer entities 1h-55 and 1h-60 transmit duplicate packets received from the respective RLC layers 1h-45 and 1h-50 via corresponding frequencies, respectively.

A procedure for activating 1h-20 or deactivating 1h-25 packet repetition is determined by the base station, wherein the base station can activate or deactivate packet repetition of each PDCP entity using a MAC Control Element (CE). Packet repetition may be activated when the transmission link is unstable or when transmission delay needs to be reduced (e.g., a service sensitive to transmission delay must be supported). Packet repetition may be deactivated when the transmission link is stable or when it is no longer necessary to reduce the transmission delay (e.g., when a service sensitive to transmission delay is not supported).

Fig. 1I illustrates a specific example of packet repetition for a next generation mobile communication system according to an embodiment of the present disclosure.

Referring to fig. 1I, each layer may process only the header and data of each layer. Fig. 1I illustrates processing operations of transmitting and receiving RLC layer entities, and operations of a lower layer (i.e., MAC layer or PHY layer) may be performed as illustrated in fig. 1D or 1E. In fig. 1I, the operation of the lower layer (MAC layer or PHY layer) may be indicated by an empty box (empty box) 1I-01.

In fig. 1I, when the PDCP layer entity processes data corresponding to PDCP SN 8, the MAC layer entity may receive MAC control information instructing to activate packet repetition.

Then, the MAC layer entity may indicate an activation instruction received from the MAC control information to the corresponding PDCP layer. The PDCP layer entity may establish additional RLC entities 1i-35 and may transmit PDCP PDUs 1i-05 corresponding to PDCP SN 8 to each of the RLC entities 1i-30 and 1 i-35.

The first RLC entity 1i-30 may assign a corresponding RLC SN 9 to an RLC header, may construct RLC PDUs 1i-10, and may deliver the RLC PDUs 1i-10 to lower layers. Upon receiving the PDCP PDU, the second RLC entity 1i-35 can allocate RLC SN 0 to the RLC header, can construct the corresponding RLC PDU 1i-15, and can deliver the RLC PDU 1i-15 to the lower layer. When data corresponding to RLC SN 9 is lost and data corresponding to

RLC SNs

10 and 11 is received among the data transmitted through the first links 1i-25, the lower edge of the window may be moved to 9. Then, as described in fig. 1G, a timer is operated. When the timer expires, retransmission of data corresponding to RLC SN 9 may be requested.

When data corresponding to

RLC SN

0 and 1 arrives via the second link 1i-20 and data corresponding to RLC SN 2 is lost, the edge of the window may be moved to 2. Then, as described in fig. 1G, a timer is operated. When the timer expires, retransmission of data corresponding to RLC SN 2 may be requested.

As described above, the packet repetition is performed using ARQ functions independently implemented in different RLC layer entities. Retransmission request, retransmission and window operations are independently performed in each RLC layer entity.

Thus, as described in fig. 1I, when packet repetition is performed using ARQ functions independently implemented in different RLC layer entities, unnecessary retransmission is requested, transmission resources are wasted, and transmission delay occurs.

Fig. 1J illustrates a problem that occurs when different RLC layers independently perform an ARQ function in packet repetition according to an embodiment of the present disclosure.

Referring to fig. 1J, table 1 shows a relationship between PDCP SNs of transmitted packets and RLC SNs allocated by each RLC entity.

TABLE 1

PDCP·SN	0	1	2	3	4	5	6	7	8	9
											RLC·SN1	7	8	9	10	11	12	13	14	15	16
RLC·SN2	0	1	2	3	4	5	6	7	8	9

In fig. 1J, when a transmitting MAC layer entity receives an instruction to activate packet repetition via MAC control information in the case of processing data corresponding to PDCP SN 0, the transmitting MAC layer entity may instruct the corresponding PDCP entity to activate packet repetition. Then, the PDCP entity may transmit duplicate data to each RLC entity starting from data corresponding to PDCP SN 0.

Table 1 and 1J-01 or 1J-02 of FIG. 1J show the relationship between PDCPSN and RLC SN allocated to each packet. It is assumed that the transmitting RLC entity transmits data corresponding to the

first RLC SN

7, 8, 9, 10, 11, 12, 13 and 14 via the first link 1j-25 and that the receiving RLC entity successfully receives all data.

In this case, the window lower edge for the first receiving RLC entity may be moved to the first RLC SN 15 as shown in 1 j-02.

Further, it is assumed that the transmitting RLC entity transmits data corresponding to the

second RLC SN

0, 1, 2, 3, 4, 5, 6 and 7 via the second link 1j-20, and data corresponding to the

second RLC SN

1, 3, 5 and 7 is lost.

Then, the second receiving RLC entity may move the window lower edge only to the second RLC SN 1 and operate the timer. When the timer expires, the second receiving RLC entity performs an RLC status report indicating that data corresponding to the

second RLC SN

1, 3, 5 and 7 is lost via the second link, and the second transmitting RLC entity 1j-35 retransmits the data corresponding to the

second RLC SN

1, 3, 5 and 7.

However, since the receiving PDCP layer has successfully received all data corresponding to

PDCP SNs

0, 1, 2, 3, 4, 5, 6, and 7 (successfully transmitted through the first link), it is unnecessary to retransmit data corresponding to

second RLC SNs

1, 3, 5, and 7 (i.e., data corresponding to

PDCP SNs

1, 3, 5, and 7) through the second link. Thus, unnecessary retransmissions are performed, which may result in waste of transmission resources and transmission delay.

The present disclosure proposes a scheme for preventing unnecessary retransmission and waste of transmission resources described in fig. 1J and reducing transmission delay described in fig. 1J in packet repetition of the next generation mobile communication system.

A first embodiment of an efficient receiving RLC layer entity of the present disclosure for preventing unnecessary retransmission and waste of transmission resources and reducing transmission delay in packet repetition of a next generation mobile communication system is as follows.

A PDCP layer entity and two corresponding transmitting RLC layer entities (a first RLC layer entity and a second RLC layer entity) which perform packet repetition sharing and maintain a mapping relationship among PDCP SN, a first RLC SN, and a second RLC SN. A mapping table is constructed and when successful receipt (RLC ACK) with respect to a first RLC SN is verified, it is determined that successful receipt with respect to a second RLC SN corresponding to the first RLC SN is achieved. On the other hand, when successful reception (RLC ACK) with respect to the second RLC SN is verified, it is determined that successful reception with respect to the first RLC SN corresponding to the second RLC SN is achieved.

2. When the first receiving RLC layer entity transmits an RLC status report and requests retransmission with respect to the first RLC SN from the first transmitting RLC layer entity, the first transmitting RLC layer entity verifies whether data corresponding to the first RLC SN is successfully transmitted to the second receiving RLC layer entity by checking a mapping table with respect to the first RLC SN.

A. When the second receiving RLC entity does not successfully receive the data corresponding to the first RLC SN for which retransmission is requested, retransmission with respect to the first RLC SN is performed.

B. When the second receiving RLC entity successfully receives the data corresponding to the first RLC SN requested to be retransmitted, the first transmitting RLC layer entity does not retransmit the data corresponding to the first RLC SN as originally transmitted, but may construct and transmit an RLC header corresponding to the first RLC SN and data having a predetermined size.

1) The data having the predetermined size may have a size of 0 bytes. That is, a PDCP header having a PDCP SN corresponding to the first RLC SN, an RLC header corresponding to the first RLC SN, and a corresponding MAC header may be constructed, and only the header may be transmitted. Thus, the window for the first receiving RLC entity does not stop, the lower edge of the window may be moved, and no further retransmissions are requested.

2) The data having a predetermined size may be random data having a small size or padding data. That is, the transmitting entity may construct a PDCP header having a PDCP SN corresponding to the first RLC SN, an RLC header corresponding to the first RLC SN, and a corresponding MAC header, and may transmit the constructed header before random data or padding data having a small size. Thus, the window for the first receiving RLC entity does not stop, the lower edge of the window may be moved, and no further retransmissions are requested.

3) The data having the predetermined size may be data corresponding to a new PDCP SN. The transmitting entity may construct a PDCP header having a new PDCP SN (PDCP SN not yet transmitted) instead of the PDCP SN corresponding to the first RLC SN, an RLC header corresponding to the first RLC SN, and a corresponding MAC header, and may transmit the constructed header before data corresponding to the new PDCP SN. Thus, the window for the first receiving RLC entity does not stop, the lower edge of the window may be moved, and no further retransmissions are requested. Therefore, when the PDCP layer transmits data corresponding to the new PDCP SN, the RLC layer simultaneously transmits a header of the first RLC SN having the retransmission, so that the first receiving RLC layer can operate without problems.

3. The second transmitting RLC entity may also apply and operate the mapping table and retransmission procedure in the same manner as the first transmitting RLC entity.

In the overview of the foregoing embodiments, the PDCP layer entity may independently establish a mapping relationship between the PDCP SN and the RLC SN of the first transmitting RLC layer entity based on the mapping relationship between the PDCP SN and the RLC SN of the second transmitting RLC layer entity. Thus, interactions between the first transmitting RLC layer entity and the second transmitting RLC layer entity may be discarded. When the first transmitting RLC layer entity (or the second transmitting RLC layer entity) identifies the RLC ACK of the received RLC status report and delivers information about the RLC SN related to the received RLC ACK to the PDCP layer entity, the PDCP layer entity may verify the PDCP SN identified as successfully delivered via the RLC ACK using the mapping information and may discard the corresponding data. In addition, the PDCP layer entity may indicate to the second transmitting RLC layer entity (or the first transmitting RLC layer entity) that the second transmitting RLC layer entity (or the first transmitting RLC layer entity) does not need to transmit data corresponding to the PDCP SN, which is identified as successfully delivered from the first transmitting RLC layer entity (or the second transmitting RLC layer entity). Alternatively, the PDCP layer entity may indicate to the second transmitting RLC layer entity (or the first transmitting RLC layer entity) that the second transmitting RLC layer entity (or the first transmitting RLC layer entity) needs to discard data corresponding to the PDCP SN. The PDCP layer entity may indicate RLC SN to a second transmitting RLC layer entity (or a first transmitting RLC layer entity) corresponding to the PDCP SN using the mapping information, and may indicate that the second transmitting RLC layer entity (or the first transmitting RLC layer entity) does not need to transmit data or needs to discard data. In packet repetition, when successful delivery via one link is identified, unnecessary repeated transmissions via the other link may be prevented.

The second transmitting RLC layer entity (or the first transmitting RLC layer entity) may construct a PDCP header and an RLC header, and may transmit only the header with respect to the RLC SN indicated as not to be transmitted or discarded by the PDCP layer entity, or may transmit new PDCP data (PDCP PDU) having a header attached, corresponding to the indicated RLC SN, as shown in the first embodiment.

Fig. 1K illustrates a mapping table set forth in a first embodiment showing the operation of an efficient transmitting RLC layer entity in packet repetition according to the present disclosure.

Referring to fig. 1K, fig. 1K illustrates a mapping table showing a relationship among PDCP SNs of a transmitting PDCP layer entity, a first RLC SN of a first RLC layer entity connected to the transmitting PDCP layer entity, and a second RLC SN of a second RLC layer entity connected to the transmitting PDCP layer entity.

In FIG. 1K, the first buffers 1K-05, the second buffers 1K-10, and the third buffers 1K-15 may be physically the same buffers or different buffers, or only some of them may be different buffers. Furthermore, these buffers may be only logically distinct buffers.

When the IP packet arrives at the PDCP layer entity, the PDCP layer entity may store the IP packet and may construct a PDCP PDU. The first buffer may indicate an address of a memory storing the IP packet or PDCP PDU and the corresponding memory address may be recorded in a mapping table, as in 1 k-25. When packet repetition is activated, the PDCP layer entity may deliver duplicate PDCP PDUs to the first transmitting RLC entity and the second transmitting RLC entity, respectively.

The second buffer may be a buffer for the first transmitting RLC entity (which stores RLC PDUs including up to RLC headers). When the data preprocessing is performed in the next generation mobile communication system, the second buffer may be a buffer of a MAC layer for storing a MAC sub-header including a MAC sub-header and a MAC SDU corresponding to an RLC PDU of the first transmitting RLC entity. Alternatively, only the first buffer may be used when the RLC header and the MAC subheader are dynamically constructed and transmitted.

The third buffer may be a buffer for the second transmitting RLC entity (which stores RLC PDUs including up to RLC headers). When the data preprocessing is performed in the next generation mobile communication system, the second buffer may be a buffer of a MAC layer for storing a MAC sub-header including a MAC sub-header and a MAC SDU corresponding to an RLC PDU of the second transmitting RLC entity. Alternatively, only the first buffer may be used when the RLC header and the MAC subheader are dynamically constructed and transmitted.

When constructing a PDCP PDU by allocating PDCP SNs as 2, 3, 4, 5, 6, and 7 for respective data and constructing a PDCP header, the transmitting PDCP layer entity may record corresponding PDCP SNs 1k-45 and corresponding memory addresses 1k-25 in a mapping table. Then, the first transmitting RLC entity may allocate the

first RLC SNs

7, 8, 9, 10, 11 and 12 to the duplicate data received by the PDCP layer, may construct an RLC header, and may record the first RLC SN 1k-50 corresponding to the PDCP SN and the corresponding memory address 1k-30 in a mapping table. The second transmitting RLC unit may allocate the

second RLC SNs

0, 1, 2, 3, 4, and 5 to the duplicate data received by the PDCP layer, may construct an RLC header, and may record the second RLC SN 1k-55 corresponding to the PDCP SN and the corresponding memory address 1k-35 in a mapping table. The segmentation information 1k-60 may be recorded in a mapping table when each transmitting RLC entity performs segmentation.

Assuming that the mapping table described above is configured, data corresponding to the

first RLC SN

7, 8, 9, 10, 11 and 12 is transmitted via the first link, only data corresponding to the first RLC SN 11 is lost and the remaining data is successfully delivered to the first receiving RLC entity (1 k-80). Then, the first receiving RLC entity may transmit an RLC status report indicating that data corresponding to the

first RLC SN

7, 8, 9 and 10 has been successfully received and that data corresponding to the first RLC SN 11 has been lost. Upon receiving the RLC status report, the first transmitting RLC entity may record successful delivery in a mapping table according to the RLC status report (1 k-70).

Assuming that the above mapping table is configured, data corresponding to the

second RLC SN

0, 1, 2, 3, 4 and 5 is transmitted via the second link, only data corresponding to the

second RLC SN

1, 2 and 4 is lost and the remaining data is successfully delivered to the second receiving RLC entity (1 k-80). The second receiving RLC entity may then transmit an RLC status report indicating that data corresponding to

second RLC SN

0, 3 and 5 has been successfully received and that data corresponding to

second RLC SN

1, 2 and 4 has been lost. Upon receiving the RLC status report, the second transmitting RLC entity may record successful delivery in the mapping table according to the RLC status report (1 k-70). The first RLC entity and the second RLC entity may receive RLC status reports at different times and may perform retransmissions at different times.

When the mapping table is configured as described above, the first transmitting RLC entity and the second transmitting RLC entity can recognize that data corresponding to

PDCP SNs

2, 3, 4, 5, and 7 is successfully transmitted and that data corresponding to only PDCP SN 6 is lost.

The first transmitting RLC entity may examine the data corresponding to the first RLC SN 11 in the mapping table and may retransmit the data corresponding to the first RLC SN 11 because no successful delivery of the data is acknowledged 1k-70. The second transmitting RLC entity may check the mapping table for data corresponding to the

second RLC SN

1, 2 and 4. Then, the second transmitting RLC entity may retransmit the data corresponding to the second RLC SN 4 since successful delivery of the data corresponding to the second RLC SN 4 is not acknowledged 1k-70. However, with respect to the data corresponding to the

second RLC SNs

1 and 2, the map indicates that the data corresponding to

PDCP SNs

3 and 4, which corresponds to the data corresponding to the

second RLC SNs

1 and 2, has been successfully delivered as the

first RLC SNs

8 and 9 through the first link.

Accordingly, the second transmitting RLC entity may retransmit data corresponding to the

second RLC SN

1 and 2 as follows.

The second transmitting RLC layer entity does not retransmit data corresponding to the second RLC SN as originally transmitted, but may construct and transmit an RLC header corresponding to the second RLC SN and data having a predetermined size.

Data of a predetermined size may have a size of 0 bytes. A PDCP header having a PDCP SN corresponding to the second RLC SN, an RLC header corresponding to the second RLC SN, and a corresponding MAC header may be constructed, and only the header may be transmitted. Thus, the window for the second receiving RLC entity does not stop, the lower edge of the window may be moved, and no further retransmissions are requested.

The data of the predetermined size may be random data or padding data of small size. That is, a PDCP header having a PDCP SN corresponding to the second RLC SN, an RLC header corresponding to the second RLC SN, and a corresponding MAC header may be constructed and transferred before random data or padding data having a small size. Thus, the window for the second receiving RLC entity does not stop, the lower edge of the window may be moved, and no further retransmissions are requested.

The data having the predetermined size may be data corresponding to a new PDCP SN. That is, a PDCP header having a new PDCP SN (not yet transmitted, e.g., PDCP SN 8) instead of the PDCP SN corresponding to the second RLC SN, an RLC header corresponding to the second RLC SN, and a corresponding MAC header may be constructed and transmitted before data corresponding to the new PDCP SN. Thus, the window for the second receiving RLC entity does not stop, the lower edge of the window may be moved, and no further retransmissions are requested. Therefore, when the PDCP layer transmits data corresponding to the new PDCP SN, the RLC layer simultaneously transmits a header of the second RLC SN having the retransmission, so that the second receiving RLC layer can operate without problems.

Fig. 1L illustrates a method for constructing data to be transmitted when a second (or first) transmitting RLC layer retransmits data identified as successfully delivered in the first (or second) transmitting RLC layer in accordance with the present disclosure.

Referring to fig. 1L, fig. 1L may be divided into the following three cases.

1. When the transmitting entity performs data preprocessing and does not segment the data to be retransmitted (1 l-05)

A. For the RLC SN to be retransmitted, a PDCP header including the corresponding PDCP SN, an RLC header including the RLC SN to be retransmitted, and a corresponding MAC header are constructed excluding the data initially transmitted. The SI field of the RLC header is set to 00 to indicate that the RLC PDU is not segmented. When padding data, random data, or data corresponding to a new PDCP SN is added later, an L field indicating the length of the MAC header indicates the corresponding length. When only the PDCP header, RLC header, and MAC header are transferred, the L field of the MAC header indicates the total length of the RLC header and PDCP header. Only the PDCP header, RLC header, and MAC header constructed as above may be transmitted. Alternatively, the PDCP header, RLC header, and MAC header may be transmitted together with padding data or random data. Alternatively, the PDCP header, RLC header, and MAC header may be transmitted together with data corresponding to the new PDCP SN.

2. When the transmitting entity performs data preprocessing and segments the data to be retransmitted (11-10)

A. For the RLC SN to be retransmitted, a PDCP header including the corresponding PDCP SN is constructed, including the RLC header of the RLC SN to be retransmitted and the corresponding MAC header, excluding the data initially transmitted. Even if the SI field of the RLC header is set to 01, 10 or 11 to indicate segmented information, the SI field needs to be reset to 00 to indicate that the RLC PDU is not segmented. When the SO field is added, the RLC header needs to be constructed by deleting the SO field. When padding data, random data, or data corresponding to a new PDCP SN is added later, an L field (indicating a length) of the MAC header indicates the corresponding length. When only the PDCP header, RLC header, and MAC header are transferred, the L field of the MAC header indicates the total length of the RLC header and PDCP header. Only the PDCP header, RLC header, and MAC header constructed as above may be transmitted. Alternatively, the PDCP header, RLC header, and MAC header may be transmitted together with padding data or random data. Alternatively, the PDCP header, RLC header, and MAC header may be transmitted together with data corresponding to the new PDCP SN.

3. When the transmitting entity dynamically generates data to be retransmitted without performing data preprocessing (11-15)

A. For the RLC SN to be retransmitted, a PDCP header including the corresponding PDCP SN is constructed, including the RLC header of the RLC SN to be retransmitted and the corresponding MAC header, excluding the data initially transmitted. The SI field of the RLC header is set to 00 to indicate that the RLC PDU is not segmented. When padding data, random data, or data corresponding to a new PDCP SN is added later, an L field (indicating a length) of the MAC header indicates the corresponding length. When only the PDCP header, RLC header, and MAC header are transferred, the L field of the MAC header indicates the total length of the RLC header and PDCP header. Only the PDCP header, RLC header, and MAC header constructed as above may be transmitted. Alternatively, the PDCP header, RLC header, and MAC header may be transmitted together with padding data or random data. Alternatively, the PDCP header, RLC header, and MAC header may be transmitted together with data corresponding to the new PDCP SN.

The first embodiment of the present disclosure has proposed and described an efficient transmission method for a transmitting RLC layer entity that performs repeated packet transmission and retransmission using packet repetition.

The following second embodiment of the present disclosure proposes and describes an efficient duplicate packet reception method for a receiving RLC layer corresponding to a transmitting RLC layer entity that performs duplicate packet transmission using packet repetition.

The present disclosure proposes another scheme for preventing unnecessary retransmission and waste of transmission resources and reducing transmission delay in packet repetition of the next generation mobile communication system described in fig. 1J.

A second embodiment of an efficient receiving RLC layer entity of the present disclosure for preventing unnecessary retransmission and waste of transmission resources and reducing transmission delay in packet repetition of a next generation mobile communication system is as follows.

1. A receiving PDCP layer entity and two corresponding receiving RLC layer entities (a first receiving RLC layer entity and a second receiving RLC layer entity) which receive duplicate packet shares and maintain a mapping relationship between PDCP SN, a first RLC SN, and a second RLC SN. The mapping table is constructed, and when the PDCP layer entity verifies successful reception with respect to the PDCP SN, the PDCP layer entity may share the first RLC SN and the second RLC SN corresponding to the PDCP SN with the first receiving RLC layer entity and the second receiving RLC layer entity. When the PDCP layer verifies that the data corresponding to the PDCP SN is successfully received, the PDCP layer may notify the first receiving RLC layer entity of the first RLC SN corresponding to the PDCP SN or an interval between the PDCP SN and the first RLC SN. Accordingly, even when data corresponding to the first RLC SN is not successfully received, the first receiving RLC layer entity determines that the data was successfully received (e.g., verifies that the data was successfully received over the second link) and moves a window of the first receiving RLC layer entity.

The PDCP layer may notify the second receiving RLC layer entity of the second RLC SN corresponding to the PDCP SN identified as successfully received or an interval between the PDCP SN and the second RLC SN. Accordingly, even when data corresponding to the second RLC SN is not successfully received, the second receiving RLC layer entity determines that the data was successfully received (e.g., verifies that the data was successfully received over the first link) and moves a window of the second receiving RLC layer entity.

2. When RLC status reporting needs to be performed, the first (or second) receiving RLC entity operates as follows.

A. Before transmitting an RLC status report indicating a NACK of a first (or second) RLC SN that was not received (e.g., determined to be lost) (before reporting the loss), the first (or second) receiving RLC entity checks the mapping table and verifies whether a PDCP SN corresponding to the first (or second) RLC SN has been successfully received in the PDCP layer (e.g., verifies whether it is indicated that the PDCP SN has been successfully received in the PDCP layer). When the PDCP layer has successfully received the PDCP SN, the first (or second) receiving RLC layer entity transmits an RLC status report indicating ACK (e.g., determines that the second (or first) receiving RLC layer entity received data) even though the first (or second) receiving RLC layer entity has not received data corresponding to the first (or second) RLC SN corresponding to the PDCP SN. When the PDCP layer has not received the PDCP SN, the first (or second) receiving RLC layer entity then uses the NACK to indicate data loss and requests retransmission of the data. Thus, unnecessary retransmission can be prevented. When data is not successfully received via the first link but is successfully received via the second link, retransmission of the data via the first link is not requested, thereby avoiding waste of transmission resources and transmission delay caused by unnecessary retransmission.

3. The window of the first (or second) receiving RLC entity operates as follows.

A. Upon receiving data from the first or second receiving RLC layer entity, the PDCP layer checks a mapping relationship between the first or second RLC SN and the corresponding PDCP SN.

B. When it is determined that data corresponding to the PDCP SN has been successfully received, the PDCP layer informs the first receiving RLC layer entity and the second receiving RLC layer entity of the corresponding first RLC SN and the corresponding second RLC SN, or an interval between the first RLC SN and the PDCP SN and an interval between the second RLC SN and the PDCP SN.

C. The first receiving RLC layer entity determines that a first RLC SN, which is not received by the first receiving RLC entity but is determined to have been successfully received by the second RLC entity, has been received based on the information received from the PDCP layer. In addition, the second receiving RLC layer entity determines that a second RLC SN, which is not received by the second receiving RLC entity but is determined to have been successfully received by the first RLC entity, has been received based on the information received from the PDCP layer.

D. The first receiving RLC layer entity and the second receiving RLC layer entity move the window by reflecting information received from the PDCP layer. That is, the first receiving RLC layer entity and the second receiving RLC layer entity move the lower edge of the window by reflecting RLC SNs that are considered to have been successfully received in the window parameters (e.g., by updating the window parameter rx_next).

Fig. 1M illustrates a mapping table applied in a second embodiment of an efficient receiving RLC layer entity of the present disclosure for preventing unnecessary retransmission and waste of transmission resources and reducing transmission delay in packet repetition of a next generation mobile communication system.

Fig. 1M illustrates a mapping table showing a mapping relationship between a PDCP SN of a receiving PDCP layer entity, a first RLC SN of a first receiving RLC layer entity connected to a transmitting PDCP layer entity, and a second RLC SN of a second receiving RLC layer entity connected to the transmitting PDCP layer entity.

Referring to fig. 1M, when PDCP PDUs reach the PDCP layer entity, the PDCP layer entity identifies PDCP SNs and records the PDCP SNs in a mapping table (1M-05). The receiving entity (UE or base station) may identify the first and second RLC SNs corresponding to the PDCP SN and may record the RLC SNs (1 m-10 and 1 m-15). The receiving entity (UE or base station) may add a field (1 m-20) indicating successful reception. The PDCP layer identifies a PDCP SN whenever a PDCP PDU is received from the lower first receiving RLC entity or the second receiving RLC entity. When it is determined that the PDCP PDU has been successfully received, the PDCP layer may notify the first receiving RLC entity or the second receiving RLC entity of the first RLC SN and the second RLC SN corresponding to the PDCP SN, or the interval between the first RLC SN and the PDCP SN and the interval between the second RLC SN and the PDCP SN. The mapping table may then be configured as in fig. 1M.

The mapping table may be configured based on the PDCP SN. When data corresponding to the first RLC SN is not received but is received in the second receiving RLC layer entity, the data may be considered as received. Successful receipt may be determined by validating fields 1 m-20. Since RLC SNs sequentially increase, even if corresponding data is not received, its relationship with PDCP SNs can be derived.

Assuming that the transmitting PDCP layer entity constructs PDCP PDUs by allocating PDCP SNs as 2, 3, 4, 5, 6, and 7 for corresponding data and constructing PDCP headers, the first transmitting RLC entity allocates

first RLC SNs

7, 8, 9, 10, 11, and 12 for duplicate data received by the PDCP layer and constructs RLC headers, and the second transmitting RLC entity allocates

second RLC SNs

0, 1, 2, 3, 4, and 5 for duplicate data received by the PDCP layer and constructs RLC headers, thereby transmitting data via lower layers.

It is assumed that data corresponding to the

first RLC SN

7, 8, 9, 10, 11 and 12 is transmitted via the first link, only data corresponding to the first RLC SN 11 is lost and the remaining data is successfully delivered to the first receiving RLC entity. Then, the first receiving RLC entity may deliver the received data to the higher PDCP layer, and the PDCP layer entity may determine that the data corresponding to

PDCP SNs

2, 3, 4, 5, and 7 have been successfully received, may configure a mapping table as in 1m-05, and may indicate the mapping table to the first receiving RLC layer entity. Further, the PDCP layer entity may record 1m-10 in the mapping table.

Assuming that the above mapping table is configured, data corresponding to the

second RLC SN

0, 1, 2, 3, 4, and 5 is transmitted via the second link, only data corresponding to the

second RLC SN

1, 2, and 4 is lost and the remaining data is successfully delivered to the second receiving RLC entity. Then, the second receiving RLC entity delivers data corresponding to the

second RLC SNs

0, 3, and 5, which have been successfully received, to the higher PDCP layer. The PDCP layer identifies PDCP SNs and discards the data (if repeated). When the data is new data, the PDCP layer may identify the data, may update a mapping table (1 m-15), and may indicate the mapping table to the second receiving RLC layer entity.

When the first receiving RLC entity needs to configure the RLC status report, the first receiving RLC entity can verify whether the first RLC SN 11 corresponding to the PDCP SN 6 is lost by checking a mapping table (or checking information indicated by the PDCP layer), and can indicate that the first RLC SN 11 has been lost and needs retransmission via the RLC status report.

When the second receiving RLC entity needs to configure the RLC status report, the second receiving RLC entity may verify that the second RLC SN 4 corresponding to the PDCP SN 6 is lost by checking the mapping table (or checking information indicated by the PDCP layer), and may indicate that the second RLC SN 4 has been lost and needs retransmission via the RLC status report. Further, regarding data corresponding to the

second RLC SNs

1 and 2, which the second receiving RLC layer entity did not receive, although the second receiving RLC layer entity did not actually receive the data, the map indicates that the

corresponding PDCP SNs

3 and 4 have been successfully received (PDCP layer indication), and the second receiving RLC layer entity considers that the data has been successfully received and configures an RLC status report indicating ACK.

When the first receiving RLC entity moves the window, the first receiving RLC entity may check the first RLC SN whenever receiving data and may move the window accordingly. In case the PDCP layer indicates a corresponding first RLC SN whenever the PDCP layer receives data from the first receiving RLC entity or the second RLC entity, the first receiving RLC entity may move the window accordingly. The first receiving RLC layer entity may move the window to 11 (1 m-25).

When the second receiving RLC entity moves the window, the second receiving RLC entity may check the second RLC SN whenever receiving data and may move the window accordingly. In case the PDCP layer indicates a corresponding second RLC SN whenever the PDCP layer receives data from the first receiving RLC entity or the second RLC entity, the second receiving RLC entity may move the window accordingly. The second receiving RLC layer entity may move the window to 4 (1 m-25). Although the second receiving RLC entity has not actually received the

second RLC SN

1 and 2, when the PDCP layer has received the corresponding

PDCP SN

3 and 4 and indicated that the corresponding

second RLC SN

1 and 2 has been successfully received (when the mapping table so indicates), the second receiving RLC entity may move the window accordingly. For example, a window parameter (rx_next) corresponding to the lower edge of the receive window may be updated accordingly.

The window of the first receiving RLC layer entity or the second receiving RLC layer entity may be moved according to the first RLC SN or the second RLC SN corresponding to the PDCP SN that was successfully received in sequence without being lost (e.g., typically the RLC SN actually received by each receiving RLC entity is moved). For example, a window parameter (rx_next) corresponding to the lower edge of the receive window may be updated accordingly.

Fig. 1N illustrates an operation of transmitting an RLC layer entity according to an embodiment of the present disclosure.

Referring to fig. 1N, when retransmission for a specific RLC SN is requested via an RLC status report, a transmitting RLC layer entity performing packet repetition first checks a mapping table (1N-05).

When it is determined that packets are lost via both links, the transmitting RLC layer entity performs retransmission (1 n-10).

However, when verifying that the packet has been successfully delivered via one link, the transmitting RLC layer entity may construct PDCP header, RLC header and MAC header, and may retransmit only the header, may retransmit the header together with random data or padding data having a predetermined size, or may transmit the header (1 n-15) together with PDCP header and data corresponding to a new PDCP SN.

Fig. 1O illustrates an operation of a receiving RLC layer entity according to an embodiment of the present disclosure.

Referring to fig. 1O, when a receiving RLC layer entity needs to perform RLC status reporting to a transmitting RLC layer entity performing packet repetition (1O-01), the receiving RLC layer entity first checks a mapping table (after checking an indication received from the PDCP layer) (1O-05).

When it is determined that packets are lost via both links, the receiving RLC layer entity transmits a NACK with respect to the lost RLC SN and requests retransmission (1 o-10). However, when verifying that the packet has been successfully delivered via one link, the receiving RLC layer entity transmits an ACK to prevent unnecessary retransmission (1 o-15), although the packet is not actually received.

Hereinafter, a window operation of the receiving RLC layer entity (1 o-20) is described.

In fig. 1O, when the receiving RLC layer entity gets the following indication from the transmitting RLC layer entity performing packet repetition or receives the following, the receiving RLC layer entity may check the mapping table (after checking the indication received from the PDCP layer) (1O-25): RLC SN corresponding to PDCP SN determined to have been successfully received from the PDCP layer, or an interval between RLC SN and PDCP SN. When it is determined that all packets via both links are lost, the receiving RLC layer entity may not update the window parameters (1 o-30) with respect to the lost RLC SN.

However, when it is verified that the packet has been successfully delivered via one link, the receiving RLC layer entity updates the window parameters and moves the window (1 o-35) according to the RLC SN successfully delivered via that link.

In the present disclosure, when an indication of packet repetition deactivation is received through MAC control information, two transmitting RLC entities for packet repetition may perform one of the following processes using the mapping table information described in the first embodiment.

1. The transmitting RLC entity, which is repeatedly generated for packets, stops transmission and empties all data ready for transmission. The transmitting RLC entity, which is not the transmitting RLC entity repeatedly generated for the packet, continues transmission.

2. The transmitting RLC entity that generates for packet repetition transmits only RLC SNs other than RLC SNs (data prepared for packet repetition only) verified to have been successfully received by a different RLC entity. The transmitting RLC entity, which is not the transmitting RLC entity repeatedly generated for the packet, continues transmission.

3. The transmitting RLC entity that repeatedly generates for a packet transmits data corresponding to RLC SNs verified to have been successfully received by a different RLC entity according to the first embodiment, and performs normal transmission (data prepared only for packet repetition) with respect to RLC SNs other than the RLC SN. The transmitting RLC entity, which is not the transmitting RLC entity repeatedly generated for the packet, continues transmission.

In the present disclosure, when an indication of packet repetition deactivation is received through MAC control information, two receiving RLC entities for packet repetition may perform one of the following procedures.

1. The receiving RLC layer entity processes data received so far by the RLC layer entity (receiving RLC layer entity configured for packet repetition) or data currently received and processed in the MAC layer and delivers the data to a higher layer.

2. The receiving RLC layer entity stops processing the data received so far by the RLC layer entity (receiving RLC layer entity configured for packet repetition) or the data currently received and processed in the MAC layer, and discards the data.

In the first embodiment of the present disclosure, the RLC layer entity may verify information about successfully received RLC SN through RLC status report, and may transfer the information to a higher layer (PDCP layer). In a second embodiment of the present disclosure, the RLC layer entity may transfer information about successfully received RLC SNs to a higher layer (PDCP layer).

In the first or second embodiment of the present disclosure, after receiving authentication information indicating successful reception from a lower layer (RLC layer), the PDCP layer may transfer the information to another lower layer (RLC layer).

Fig. 1P illustrates a configuration of a UE according to an embodiment of the present disclosure.

Referring to fig. 1p, the ue includes a Radio Frequency (RF) processor 1p-10, a baseband processor 1p-20, a memory unit 1p-30, and a controller 1p-40.

The RF processors 1p-10 perform functions for transmitting or receiving signals through wireless channels, such as frequency band conversion and amplification of signals. The RF processors 1p-10 up-convert the baseband signals supplied from the baseband processors 1p-20 into RF band signals to transmit the RF band signals through the antennas, and down-convert the RF band signals received through the antennas into baseband signals. For example, the RF processors 1p-10 may include transmit filters, receive filters, amplifiers, mixers, oscillators, digital-to-analog converters (DACs), and analog-to-digital converters (ADCs). Although fig. 1P shows only one antenna, the UE may include multiple antennas. In addition, the RF processors 1p-10 may include a plurality of RF chains. In addition, the RF processors 1p-10 may perform beamforming. For beamforming, the RF processors 1p-10 may adjust the phase and intensity of each of the signals transmitted and received through multiple antennas or antenna elements. The RF processor may perform MIMO and may receive multiple layers when performing MIMO. The RF processors 1p-10 may perform receive beam scanning (sweep) by appropriately arranging a plurality of antennas or antenna elements under the control of a controller, or may adjust the direction and width of the receive beam so that the receive beam is coordinated with the transmit beam.

The baseband processors 1p-20 convert the baseband signals and bit streams according to the physical layer specifications of the system. For example, in data transmission, the baseband processors 1p-20 encode and modulate a transmission bit stream to generate complex symbols. In data reception, the baseband processor 1p-20 demodulates and decodes the baseband signal supplied from the RF processor 1p-10, thereby reconstructing the received bit stream. For example, according to OFDM, in data transmission, baseband processors 1p-20 generate complex symbols by encoding and modulating a transmission bit stream, map the complex symbols to subcarriers, and construct OFDM symbols by Inverse Fast Fourier Transform (IFFT) and Cyclic Prefix (CP) insertion. In data reception, the baseband processor 1p-20 divides the baseband signal supplied from the RF processor 1p-10 into OFDM symbols, reconstructs the signal mapped to the subcarriers by Fast Fourier Transform (FFT), and reconstructs the received bit stream by demodulation and decoding.

As described above, the baseband processors 1p-20 and the RF processors 1p-10 transmit and receive signals. Thus, the baseband processors 1p-20 and the RF processors 1p-10 may be referred to as transmitters, receivers, transceivers or communication units. At least one of the baseband processors 1p-20 and the RF processors 1p-10 may include a plurality of communication modules to support a plurality of different radio access technologies. Furthermore, at least one of the baseband processors 1p-20 and the RF processors 1p-10 may comprise different communication modules for processing signals in different frequency bands. For example, the different radio access technologies may include LTE networks, NR networks, and so on. In addition, the different frequency bands may include an ultra high frequency (SHF) band (e.g., 2.5GHz and 5 GHz) and a millimeter wave band (e.g., 60 GHz).

The storage units 1p-30 store data such as default programs, applications, and configuration information for operating the UE. The memory units 1p-30 provide stored data in accordance with requests from the controllers 1 p-40.

The controllers 1p-40 control the overall operation of the UE. For example, the controllers 1p-40 transmit and receive signals through the baseband processors 1p-20 and the RF processors 1 p-10. Further, the controllers 1p-40 record and read data in the storage units 1 p-30. To this end, the controllers 1p-40 may comprise at least one processor. For example, the controllers 1p-40 may include a Communication Processor (CP) that performs control of communication and an Application Processor (AP) that controls higher layers such as applications. The controller 1p-40 may include a processor-to-multi-connection processor 1p-42 that performs operations for multi-connection mode.

Referring to fig. 1Q, the base station includes an RF processor 1Q-10, a baseband processor 1Q-20, a backhaul communication unit 1Q-30, a storage unit 1Q-40, and a controller 1Q-50.

The RF processors 1q-10 perform functions for transmitting or receiving signals through wireless channels, such as frequency band conversion and amplification of signals. That is, the RF processors 1q-10 up-convert the baseband signals supplied from the baseband processors 1q-20 into RF band signals to transmit the RF band signals through the antennas, and down-convert the RF band signals received through the antennas into baseband signals. For example, the RF processors 1q-10 may include transmit filters, receive filters, amplifiers, mixers, oscillators, DACs, and ADCs. Although fig. 1Q shows only one antenna, a base station may include multiple antennas. In addition, the RF processor 1q-10 may include a plurality of RF chains. In addition, the RF processors 1q-10 may perform beamforming. For beamforming, the RF processor 1q-10 may adjust the phase and intensity of each of the signals transmitted and received through multiple antennas or antenna elements. The RF processor may transmit one or more layers to perform downlink MIMO.

The baseband processor 1q-20 converts the baseband signal and the bit stream according to the physical layer specification of the first radio access technology. For example, in data transmission, the baseband processor 1q-20 encodes and modulates a transmission bit stream to generate complex symbols. In data reception, the baseband processor 1q-20 demodulates and decodes the baseband signal supplied from the RF processor 1q-10, thereby reconstructing the received bit stream. For example, according to OFDM, in data transmission, the baseband processor 1q-20 generates complex symbols by encoding and modulating a transmission bit stream, maps the complex symbols to subcarriers, and constructs OFDM symbols by IFFT and CP insertion. In data reception, the baseband processor 1q-20 divides the baseband signal supplied from the RF processor 1q-10 into OFDM symbols, reconstructs the signal mapped to the subcarriers through FFT, and reconstructs the reception bit stream through demodulation and decoding. As described above, the baseband processors 1q-20 and the RF processors 1q-10 transmit and receive signals. Thus, the baseband processor 1q-20 and the RF processor 1q-10 may be referred to as a transmitter, receiver, transceiver, communication unit or wireless communication unit.

The communication units 1q-30 provide interfaces for performing communication with other nodes in the network.

The storage units 1q-40 store data such as default programs, applications, and configuration information for operating the base station. In particular, the storage unit 1q-40 may store information on bearers allocated to the connected UE, measurement results reported from the connected UE, and the like. In addition, the storage units 1q-40 may store information as criteria for determining whether to provide or stop multiple connections to the UE. The storage units 1q-40 provide stored data in accordance with requests from the controllers 1 q-50.

The controllers 1q-50 control the overall operation of the base station. For example, the controller 1q-50 transmits and receives signals through the baseband processor 1q-20 and the RF processor 1q-10 or through the backhaul communication unit 1 q-30. Further, the controller 1q-50 records and reads data in the storage units 1 q-40. To this end, the controllers 1q-50 may comprise at least one processor. The controller 1q-50 may include a multi-connection processor 1q-52 that performs processing for operation in a multi-connection mode.

In the above detailed embodiments of the present disclosure, components included in the present disclosure are expressed in singular or plural numbers according to the presented detailed embodiments. However, to facilitate description appropriate to the presented circumstances, singular forms or plural forms are selected, and various embodiments of the present disclosure are not limited to single elements or multiple elements thereof. Furthermore, a plurality of elements expressed in the specification may be configured as a single element, or a single element in the specification may be configured as a plurality of elements.

While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A packet processing method of a transmitting device in a wireless communication system, the transmitting device comprising a packet data convergence protocol PDCP entity, a first radio link control RLC entity, a second RLC entity, and a medium access control MAC entity, the method comprising:

delivering, by the PDCP entity, a first PDCP protocol data unit, PDU, to be transmitted to a receiving device, to the first RLC entity;

delivering, by the PDCP entity, a second PDCP PDU to be transmitted to the receiving device to the second RLC entity, the first PDCP PDU and the second PDCP PDU being associated with a packet repetition;

obtaining, by the PDCP entity, first information indicating successful delivery of the first PDCP PDU from the first RLC entity, in case the first RLC entity receives a positive acknowledgement associated with the first PDCP PDU transmitted to the receiving device; and

Delivering second information indicating discard of the second PDCP PDU to the second RLC entity through the PDCP entity based on the first information,

wherein, in case a second RLC SDU is indicated as not being received by the receiving device and corresponds to the second PDCP PDU indicated as discarded by the PDCP entity, a second RLC PDU is generated by the second RLC entity using a third PDCP PDU and based on an RLC sequence number associated with the second RLC SDU, and

wherein the generated second RLC PDU is transmitted to the receiving apparatus through the second RLC entity.

2. The method of claim 1, further comprising:

obtaining, by the PDCP entity, third information indicating successful delivery of the second PDCP PDU from the second RLC entity when the second RLC entity receives a positive acknowledgement associated with the second PDCP PDU transmitted to the receiving device, and

fourth information indicating discard of the first PDCP PDU is delivered to the first RLC entity through the PDCP entity based on the third information.

3. The method of claim 2, wherein when a first RLC SDU is indicated as not being received by the receiving device and corresponds to the first PDCP PDU indicated as discarded by the PDCP entity, a first RLC PDU is generated by the first RLC entity using a third PDCP PDU and based on an RLC sequence number associated with the first RLC SDU, and

Wherein the generated first RLC PDU is transmitted to the receiving apparatus through the first RLC entity.

4. The method according to claim 1,

wherein a mapping table associated with transmission of the first PDCP PDU or the second PDCP PDU is updated.

5. A transmitting device in a wireless communication system, the transmitting device comprising a packet data convergence protocol, PDCP, entity, a first radio link control, RLC, entity, a second RLC entity, and a medium access control, MAC, entity, the transmitting device configured to:

6. The transmitting device of claim 5, further configured to:

7. The transmitting device of claim 6, wherein when a first RLC SDU is indicated as not being received by the receiving device and corresponds to the first PDCP PDU indicated as discarded by the PDCP entity, a first RLC PDU is generated by the first RLC entity using a third PDCP PDU and based on an RLC sequence number associated with the first RLC SDU, and

8. The transmitting device of claim 5, wherein a mapping table associated with transmission of the first PDCP PDU or the second PDCP PDU is updated.