KR101595575B1 - Apparatus and method for transmitting/receiving data in a mobile communication system - Google Patents

Abstract

The present invention distinguishes between initial transmission and retransmission when transmitting PDCP (Packet Data Convergence Protocol) packets, thereby reducing load on packet duplication inspection of the PDCP layer and effectively canceling retransmitted packets, thereby increasing the efficiency of radio resources. To this end, the present invention provides a method of transmitting data in a mobile communication system, comprising the steps of: constructing a PDU by adding a field indicating PDCP retransmission to a Packet Data Unit (PDU) type; And transmitting the configured PDU.

RLC re-establishment, Packet Data Unit (PDU), Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), Medium Access Control (MAC)

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for transmitting / receiving data in a mobile communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly, to a data transmission apparatus and method.

BACKGROUND ART Generally, a Universal Mobile Telecommunication Service (UMTS) system is based on a Global System for Mobile Communications (GSM) and a General Packet Radio Services (GPRS), which are European mobile communication systems, and a wideband code division multiple access : W-CDMA) is used as a third generation asynchronous mobile communication system.

The 3rd Generation Partnership Project (3GPP), which is in charge of UMTS standardization, is discussing LTE (Long Term Evolution) as a next generation mobile communication system of UMTS system. LTE is a technology to realize high-speed packet-based communication of about 100 Mbps with the target of commercialization in 2010 or so. Various schemes are being discussed for this purpose. For example, there are discussions to reduce the number of nodes located on the communication path by simplifying the structure of the network, and to approach the wireless protocols as much as possible to the wireless channel.

1 is a block diagram illustrating an example of a structure of an LTE mobile communication system.

1, an Evolved Radio Access Network (E-RAN) 110 includes an Evolved Node B (hereinafter referred to as 'ENB' or 'Node B') 120, 122, 124, 126 and 128, hereinafter, referred to as '120 to 128') and anchor nodes 130 and 132, respectively.

A user equipment (UE) 101 is connected to an Internet Protocol (IP) network by an E-UTRAN 110.

The ENBs 120 to 128 correspond to an existing Node B of the UMTS system and are connected to the UE 101 through a wireless channel. Unlike the existing node B, the ENBs 120 to 128 perform a more complex role. In LTE, all user traffic including real-time services such as Voice over Internet Protocol (VoIP) over the Internet protocol is serviced through a shared channel. Therefore, a device for collecting and scheduling the situation information of UEs is needed. ENBs 120 to 128 are responsible.

HARQ (Hybrid ARQ) is performed between the ENBs 120 to 128 and the UE 101 in the LTE as in HSDPA or Enhanced Dedicated Channel (E-DCH) (ARQ) can be performed in an upper layer, and the separate ARQ can also be performed between the UE 101 and the ENBs 120 to 128 .

In order to achieve transmission rates of up to 100 Mbps, LTE systems are expected to use Orthogonal Frequency Division Multiplexing (OFDM) as a radio access technology in a 20 MHz bandwidth. The LTE system uses an Adaptive Modulation and Coding (AMC) scheme for determining a modulation scheme and a channel coding rate according to a channel state of a UE.

Meanwhile, the W-CDMA standard is approved by the 3GPP (3rd Generation Partnership Project), and the Release phase is set according to the adopted technology. In principle, the upper release guarantees backward compatibility with the lower standard.

In wireless mobile communication technologies such as W-CDMA, power control is required to compensate for signal deterioration on the physical radio channel between the transmitter and the receiver, and a protocol for reliable transmission and reception in the transport layer Is required.

Therefore, in W-CDMA, a protocol called RLC (Radio Link Control) is provided to secure a reliable data transmission method between a transmitting end and a receiving end. In particular, in the case of AM (Acknowledge Mode) RLC, various procedures and control PDUs (Protocol Data Units) are used for in-sequence delivery in the sequence number (SN) sequence.

2 is a block diagram of a radio protocol of a mobile communication system.

2, the wireless protocol of the LTE mobile communication system includes Packet Data Convergence Protocols (PDCP) 205 and 240, Radio Link Control (RLC) 210 and RLC (Medium Access Control) 215 and 230. The PDCP (Packet Data Convergence Protocol) 205 and 240 are responsible for operations such as IP header compression / decompression and Radio Link Control (RLC) 210 and 235 are PDCP PDU ) To an appropriate size to perform an ARQ operation or the like. The MACs 215 and 230 are connected to a plurality of RLC layer devices configured in a terminal, multiplex RLC PDUs into MAC PDUs, and demultiplex RLC PDUs from MAC PDUs. The physical layers 220 and 225 perform channel coding and modulation on the upper layer data, transmit them to a wireless channel by making OFDM symbols, demodulate OFDM symbols received through a wireless channel, channel-decode and transmit the OFDM symbols to an upper layer . Data input to a protocol entity based on transmission is referred to as an SDU (Service Data Unit), and output data is referred to as a PDU (Protocol Data Unit).

In the LTE system, the layer for ensuring packet retransmission, reordering, redundancy checking, and data forwarding at the time of re-establishment or handover is the PDCPs 205 and 240. Traffic processing of the RLCs 210 and 235 is classified into an RLC AM (acknowledged mode) and an RLC UM (unacknowledged mode).

The RLC AM checks whether a transmission packet is transmitted, discards it in a buffer in the PDCP layer, and transmits a packet whose transmission is not confirmed when the RLC AM is reset. The receiving side of the packet ensures the order of the packets and performs redundancy check.

Unlike the RLC AM operation, the RLC UM does not check whether a transmission packet is transmitted or not, and does not perform packet retransmission and handover guarantee duplication checking.

FIG. 3 is a flowchart illustrating a packet transmission process in the RLC AM that performs packet redundancy check and redundancy check.

In step 301, the transmission PDCP 220 stores the packet in the buffer. Then, in step 303, the transmission PDCP 330 transmits the stored packet to the transmission PLC 330. Thereafter, the transmitting RLC 330 transmits a packet to the receiving RLC 340 in step 305, and the receiving RLC 340 transmits the packet to the receiving PDCP 350 in step 307. At the same time, the receiving RLC 340 transmits a packet transmission acknowledgment message to the transmitting RLC 330 in step 309. In step 311, the transmitting RLC 330, which has received the packet transmission acknowledgment message, transmits the packet transmission acknowledgment message received in step 309 to the transmitting PDCP 320. In step 313, the transmission PDCP 320 discards the corresponding packet from the buffer.

As shown in FIG. 3, if a RLC layer transmits a transmission acknowledgment message after storing a packet to be transmitted in a buffer before re-establishment, the RCP discards the packet transmitted from the PDCP buffer.

However, if a reset procedure occurs, packets that can not be transmitted due to transmission and re-establishment of packets not confirmed to be transmitted simultaneously. At the other PDCP layer receiving the packet, it checks the received packets and guarantees order, and sends them to the upper layer. The PDCP layer that receives the packet stores the packets that are out of sequence in the buffer for order guarantee and redundancy check. In the PDCP layer that receives the packet, if there is a packet in the buffer, it should always check with the packet of the received packet buffer to check whether it is a duplicate packet. Since the sequence number (SN) managed by the PDCP layer is 0 ~ 4095, a comparison of 4000 times or more is required. Duplicate packet inspection can be done only for packets that have already been transmitted. However, since the PDCP standard does not distinguish between the initial transmission packet and the retransmission packet, all packets are duplicated.

4 is a diagram illustrating an example of PDCP PDUs transmitted by being divided into a plurality of RLC PDUs.

After receiving a status report in the PDCP layer, a packet confirmed to be transmitted can cancel the transmission to the lower layer (RLC). However, even if one RLC PDU 401 is transmitted and the remaining RLC PDUs 403, 405, 407, and 409 need not be transmitted, the retransmission packet is divided into several RLC PDUs, The RLC can not cancel the transmission.

As shown in FIG. 4, when a packet that does not need to be transmitted is transmitted, wireless resources are wasted. Therefore, it is required to improve the radio resource efficiency by correctly distinguishing the initial transmission and the retransmission.

The present invention provides a method and apparatus for distinguishing an initial transmission from a retransmission when transmitting a PDCP packet.

The present invention also provides a method and apparatus for reducing the load on the packet duplication check of the PDCP layer.

The present invention also provides an apparatus and method for effectively canceling retransmitted packets to increase the efficiency of radio resources.

A data transmission method in a mobile communication system includes a data / control field indicating initial transmission or retransmission and a PDCP PDU including a PDU type field indicating segmentation if packet retransmission is indicated in the data / data convergence protocol packet data unit); And transmitting the configured PDCP PDU.
A method for receiving data in a mobile communication system includes receiving a PDCP PDU including a data / control field and a PDU type field of a packet data unit (PDU); Determining whether an initial transmission or retransmission is based on the data / control field; And determining whether the data / control field is segmented if the data / control field indicates retransmission.
In a mobile communication system, a data transmission apparatus includes a data / control field indicating initial transmission or retransmission, and a PDCP PDU packet including a PDU type field indicating segmentation if the retransmission is indicated in the data / a data convergence protocol packet data unit; And a transmitter for transmitting the configured PDCP PDU.
A data receiving apparatus in a mobile communication system includes: a receiving unit for receiving a PDCP PDU (Packet Data Convergence Protocol Packet Data Unit) including a PDU type field of a data / control field and a packet data unit (PDU); And a control unit for determining whether the data or control field is an initial transmission or retransmission based on the data / control field and determining whether the data or control field is segmented when the data / control field indicates retransmission.

The present invention distinguishes between initial transmission and retransmission when transmitting a PDCP packet, thereby reducing the load on the packet duplication check of the PDCP layer and effectively canceling the retransmitted packet, thereby increasing the efficiency of the radio resource.

The operation principle of the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions of the present invention and may be changed according to the intention or custom of the user and the operator. Therefore, the definition should be based on the contents throughout this specification.

The present invention provides a method and apparatus for distinguishing between initial transmission and retransmission when transmitting a PDCP packet in a mobile communication system, reducing the load on packet duplication inspection of the PDCP layer and efficiently canceling retransmitted packets, . The present invention can be applied not only to the LTE mobile communication system but also to various communication systems that perform packet data transmission.

Conventionally, the PDU type of the PDCP is defined as shown in Table 1 below. A "000" bit indicates a PDCP status report, a "001" bit indicates a ROHC (Robust Header Compression) feedback packet, and a "010-111" bit indicates a reservation field. Table 2 below defines the data / control field. As shown in Table 2 below, a "0" bit indicates a control PDU, and a "1" bit indicates a data PDU.

<Table 1>

<Table 2>

However, in the present invention, "010" of 010-111 reserved in Table 1 is further defined as a PDCP re-transmission packet as shown in Table 3 below.

<Table 3>

In the case of the initial transmission, the transmission PDCP 320 sets the D / C field described in Table 2 as "1 &quot; On the other hand, in case of retransmission, the transmission PDCP 320 sets the D / C field to "0 " and transmits the PDU with the PDU type set to" 010 ". However, in case of retransmission, the D / C field is not limited to "0" bits and the PDU type is not limited to "010" bits.

If the D / C field is "1 ", the receiving PDCP 350 proceeds to the PDCP procedure after the order is guaranteed without performing redundancy checking with a packet that does not need duplicate checking as the original transmission packet. On the other hand, when the D / C field is " 0 " and the PDU type is " 000 "in the receiving PDCP 350, Performs processing related to RoHC (Robust Header Compression) feedback, and performs PDCP processing after the D / C field is "0 " and the PDU type is" 010 "

When the PDU type of the PDCP PDU is "010 ", i.e., when the PDCP re-transmission packet is transmitted, the transmitting RLC 330 segments the packet that is not" 010 " Since the retransmitted packet is not segmented, if the transmission cancellation of the packet is received from the PDCP layer, the RLC layer can immediately cancel the transmission of the packet.

5 is a flowchart illustrating an operation of a PDCP in a transmission RLC AM mode according to an embodiment of the present invention.

The transmitting PDCP 320 determines in step 501 whether the data to be transmitted is a retransmission acknowledgment. If it is not retransmission, the transmission PDCP 320 sets the D / C field to "1" in step 507 and performs a series of PDCP processing on the data to be transmitted in step 505. [ However, if the data to be transmitted is retransmission, the transmitting PDCP 320 sets the D / C field to "0 " and the PDU type to" 010 "in step 503 according to the embodiment of the present invention. After step 503, the transmitting PDCP 320 performs a series of PDCP processing in step 505. [

6 is a flowchart illustrating an operation of a PDCP in a received RLC AM mode according to an embodiment of the present invention.

In step 601, the receiving PDCP 350 checks the D / C field. If the D / C field is a "1" bit, the receiving PDCP 350 recognizes the packet as the first transmission packet in the same manner as in the prior art in step 611 and does not need to perform redundancy checking. After processing, proceed with the PDCP procedure. However, if the D / C field is a "0" bit, the receiving PDCP 350 checks the PDU type in step 603. If the PDU type is "000" bits, the receiving PDCP 350 performs a PDCP status report related process in step 609. [ If the PDU type is "001" bit, the receiving PDCP 350 performs RoHC feedback related processing in step 607. [ If the PDU type is "010" bit, the receiving PDCP 350 performs duplicate checking in step 605. [ Thereafter, the receiving PDCP 350 proceeds to step 611 and performs a PDCP procedure after the order guaranteeing process.

7 is a flowchart illustrating an operation of a transmission RLC AM according to an embodiment of the present invention.

The transmitting RLC 330 determines in step 701 whether the PDU type of the PDCP PDU is "010 " and the D / C field is" 0 ". If the PDU type of the PDCP PDU is "010" and the D / C field is not 0, the transmitting RLC 330 segmentizes the PDCP PDU in step 705 as shown in FIG. However, when the PDU type of the PDCP PDU is "010 " and the D / C field is 0, the transmission RLC 330 does not segment.

8 is a block diagram of a data transmitting and receiving apparatus in a mobile communication system according to an embodiment of the present invention.

In the mobile communication system, a data transmitting and receiving apparatus is composed of a transmitting node 810 and a receiving node 820.

The PDCP entity of the PDCP layer exists in a pair as well as the RLC entity of the RLC layer. Each entity consists of a transmitting side for transmitting an arbitrary packet in its own entity and a receiving side for receiving the packet.

The first control unit 815 includes a first PDCP PDU processing unit 815a, a first PDCP PDU processing unit 815b, a first PDCP PDU processing unit 815b, And an RLC PDU processing unit 815b.

The first PDCP PDU processing unit 815a sets the D / C field described in Table 2 as "1 &quot; Then, the first PDCP PDU processing unit 815a sets the D / C field to "0 " in the case of retransmission according to the embodiment of the present invention, sets the PDU type to" 010 "

If the PDU type of the PDCP PDU is not 010, i.e., the PDCP re-transmission packet, the first RLC PDU processing unit 815b segments the PDCP PDU if the PDU type of the PDCP PDU is not "010 ".

The first receiving unit 813 receives data received from the receiving node 820 and the first transmitting unit 811 transmits data to be transmitted to the receiving node 820.

The second control unit 825 includes a second PDCP PDU processing unit 825a, a second PDCP PDU processing unit 820b, and a second PDCP PDU processing unit 820b. The second control unit 825 includes a second transmitting unit 821, a second receiving unit 823, and a second controlling unit 825. And an RLC PDU processing unit 825b.

The second RLC PDU processing unit 825b performs RLC processing on the data transmitted from the transmitting node 810. [

When the D / C field of the data processed by the second RLC PDU processing unit 825b is "1 ", the second PDCP PDU processing unit 825a regards the first transmission packet as a packet which does not need to perform redundancy check The PDCP procedure is carried out after ensuring the order without performing duplicate inspection. If the D / C field of the data processed by the second RLC PDU processing unit 825b is "0 " and the PDU type is" 000 ", the second PDCP PDU processing unit 825a performs PDCP status report- When the type is "001 ", RoHC feedback related processing is performed. When the PDU type is" 010 ", duplicate checking is performed and PDCP processing is performed after the order guarantee processing.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the scope of the appended claims, and equivalents thereof.

1 is a block diagram illustrating an example of a structure of an LTE mobile communication system;

2 is a wireless protocol structure diagram of a mobile communication system,

FIG. 3 is a flowchart illustrating a packet transmission process in the RLC AM that performs packet redundancy check and redundancy check,

4 is a diagram illustrating an example of PDCP PDUs transmitted by being divided into a plurality of RLC PDUs,

5 is a flowchart illustrating an operation of a PDCP in a transmission RLC AM mode according to an embodiment of the present invention.

6 is a flowchart illustrating an operation of a PDCP in a received RLC AM mode according to an embodiment of the present invention.

FIG. 7 is a flowchart illustrating an operation of a transmission RLC AM according to an embodiment of the present invention. FIG.

8 is a block diagram of a data transmitting and receiving apparatus in a mobile communication system according to an embodiment of the present invention.

Claims (12)

A method of transmitting data in a mobile communication system, A PDCP PDU PDU including a data / control field indicating initial transmission retransmission and a PDU type field indicating segmentation if retransmission is indicated in the data / control field Process; And And transmitting the configured PDCP PDUs in the mobile communication system. The method according to claim 1, Further comprising the step of not performing segmentation in a radio link control (RLC) layer when indicating retransmission in the data / control field. A method for receiving data in a mobile communication system, Receiving a PDCP PDU (Packet Data Convergence Protocol Packet Data Unit) including a data / control field and a PDU type field of a packet data unit (PDU); Determining whether an initial transmission or retransmission is based on the data / control field; And And determining whether the data / control field is segmented if it indicates retransmission in the data / control field. A data transmission apparatus in a mobile communication system, A PDCP PDU PDU including a data / control field indicating initial transmission retransmission and a PDU type field indicating segmentation if retransmission is indicated in the data / control field ; And And a transmitter for transmitting the configured PDCP PDUs. 5. The method of claim 4, Wherein the control unit does not perform segmentation in a radio link control (RLC) layer when it indicates retransmission in the data / control field. A data receiving apparatus in a mobile communication system, A receiving unit for receiving a PDCP PDU including a data / control field and a PDU type field of a packet data unit (PDU); And The mobile communication system according to claim 1, further comprising a controller for determining whether the data / control field is an initial transmission or retransmission based on the data / control field, and determining whether to segment the data or control field if the data / control field indicates retransmission. Data receiving apparatus. The method according to claim 1, Wherein the PDU type field indicates one of a status report related process of the PDCP, a robust header compression (RoHC) feedback related process, and a duplication related process. The method of claim 3, Wherein the PDU type field indicates one of a status report related process of the PDCP, a robust header compression (RoHC) feedback related process, and a duplication related process. 5. The method of claim 4, Wherein the PDU type field indicates one of a status report related process of the PDCP, a robust header compression (RoHC) feedback related process, and a duplication related process. The method according to claim 6, Wherein the PDU type field indicates one of a status report related process of the PDCP, a robust header compression (RoHC) feedback related process, and a duplication related process. The method of claim 3, Further comprising the step of not performing segmentation in the RLC layer when it indicates retransmission in the data / control field. The method according to claim 6, And not performing segmentation in the RLC layer when the mobile station indicates retransmission in the data / control field.

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