KR20160046562A - Method for transmitting uplink data in a wireless communication system and an user equipment for operating the same - Google Patents

Abstract

The present invention relates to a method of transmitting uplink data in a wireless communication system and a terminal using the same, and more particularly, to a method and apparatus for transmitting data in a buffer of a medium access control (MAC) layer when data is transmitted to a TCP / IP (Transmission Control Protocol / Comparing the size and the threshold value; Transmitting the data transferred to the TCP / IP layer to a Packet Data Convergence Protocol (PDCP) layer when the buffer size is smaller than the threshold value; And uplink transmission of data transmitted to the MAC layer.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for transmitting uplink data in a wireless communication system and a terminal using the method.

The present invention relates to a wireless communication system, and more particularly, to an uplink data transmission method and a terminal using the same.

As an example of a wireless communication system to which the present invention can be applied, a 3GPP LTE (Third Generation Partnership Project) Long Term Evolution (LTE) communication system will be schematically described.

1 is a diagram schematically showing an E-UMTS network structure as an example of a wireless communication system. The Evolved Universal Mobile Telecommunications System (E-UMTS) system evolved from the existing Universal Mobile Telecommunications System (UMTS), and is currently undergoing basic standardization work in 3GPP. In general, E-UMTS may be referred to as an LTE (Long Term Evolution) system. For details of the technical specifications of UMTS and E-UMTS, refer to Release 7 and Release 8 of the " 3rd Generation Partnership Project (Technical Specification Group Radio Access Network ").

1, an E-UMTS includes an Access Gateway (AG) located at the end of a User Equipment (UE), a Node B (eNode B), and an E-UTRAN, . The base station may simultaneously transmit multiple data streams for broadcast services, multicast services, and / or unicast services.

One base station has more than one cell. The cell is set to one of the bandwidths of 1.44, 3, 5, 10, 15, and 20 Mhz, and provides downlink or uplink transmission service to a plurality of UEs. Different cells may be set up to provide different bandwidths. The base station controls data transmission / reception for a plurality of terminals. The base station transmits downlink scheduling information for downlink (DL) data, and notifies the UE of time / frequency region, coding, data size, and HARQ related information to be transmitted to the UE. In addition, the base station transmits uplink scheduling information to uplink (UL) data, and notifies the UE of time / frequency domain, coding, data size, and HARQ related information that the UE can use. An interface for transmitting user traffic or control traffic may be used between the base stations. The Core Network (CN) can be composed of an AG and a network node for user registration of the UE. The AG manages the mobility of the terminal in units of TA (Tracking Area) composed of a plurality of cells.

Wireless communication technologies have been developed to LTE based on WCDMA, but the demands and expectations of users and operators are continuously increasing. In addition, since other wireless access technologies are continuously being developed, new technology evolution is required to be competitive in the future. Cost reduction per bit, increased service availability, use of flexible frequency band, simple structure and open interface, and proper power consumption of terminal.

Currently, the 3GPP LTE (A) system has an unbalanced communication environment in which the maximum data rate of the downlink is higher than the maximum data rate of the uplink. In this structure, when bidirectional Transmission Control Protocol (TCP) communication is performed, the downlink data rate is lowered due to the delay of the uplink TCP response packet for downlink data due to data buffered for uplink data transmission there was.

It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present invention and is not to be construed as an admission that the prior art is known to those skilled in the art.

It is an object of the present invention to provide a method for efficiently transmitting data by managing uplink data in a wireless communication system that improves the above-mentioned problems, and a terminal for the same.

The technical problems to be solved by the present invention are not limited to the technical problems and other technical problems which are not mentioned can be understood by those skilled in the art from the following description.

According to an aspect of the present invention, in a method for transmitting uplink data in a wireless communication system, when data is transferred to a TCP / IP (Transmission Control Protocol / Internet Protocol) layer, a buffer size of a Medium Access Control And comparing the threshold value with the threshold value; Transmitting the data transferred to the TCP / IP layer to a Packet Data Convergence Protocol (PDCP) layer when the buffer size is smaller than the threshold value; And uplink transmission of data transmitted to the MAC layer.

According to another aspect of the present invention, there is provided a terminal for transmitting uplink data in a wireless communication system, the terminal comprising: a radio frequency (RF) module; And a process of controlling the radio frequency module, wherein when the data is transferred to a TCP / IP (Transmission Control Protocol / Internet Protocol) layer, the buffer size of the Medium Access Control (MAC) And transmits the data transferred to the TCP / IP layer to a PDCP (Packet Data Convergence Protocol) layer when the buffer size is smaller than the threshold value, and transmits the data to the MAC layer A terminal is provided.

The size of the data transferred to the PDCP layer may be smaller than the difference between the threshold value and the buffer size.

Preferably, when the data is transferred to the TCP / IP layer, the data is divided into a data packet and an acknowledgment packet, and the priority of the data packet is set lower than the priority of the response packet have.

Preferably, in the step of transmitting the data to the PDCP layer, the response packet is delivered according to the priority order, and the data packet can be delivered only when an extra buffer size exists.

Preferably, the threshold value may be set considering a margin between a maximum UL transmission rate and a data processing rate in the PDCP layer, the RLC layer, and the MAC layer.

According to the present invention, by managing the uplink TCP data, it is possible to prevent the delay of the response packet to the downlink TCP data and the lowering of the downlink TCP transmission rate, thereby enabling efficient bidirectional TCP communication.

The effects obtainable in the embodiments of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be obtained from the description of the embodiments of the present invention described below by those skilled in the art Can be clearly understood and understood. In other words, undesirable effects of implementing the present invention can also be obtained by those skilled in the art from the embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. It is to be understood, however, that the technical features of the present invention are not limited to the specific drawings, and the features disclosed in the drawings may be combined with each other to constitute a new embodiment. Reference numerals in the drawings refer to structural elements.
1 shows an E-UMTS network structure as an example of a wireless communication system.
2 shows a control plane and a user plane structure of a radio interface protocol between a UE and an E-UTRAN based on the 3GPP radio access network standard.
3 shows the physical channels used in the 3GPP LTE system and a general signal transmission method using them.
4 shows a structure of a radio frame used in an LTE system.
5 shows a resource grid for a downlink slot.
6 illustrates the structure of a downlink sub-frame.
7 shows a structure of an uplink subframe used in LTE.
8 shows UL HARQ operation in the LTE system.
9 shows an uplink transmission operation in the LTE-A system.
10 is a flowchart illustrating a data transmission method in an uplink according to an embodiment of the present invention.
11 illustrates a base station and a terminal that can be applied to an embodiment of the present invention.

The following description is to be understood as illustrative and non-limiting, such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access And can be used in various wireless access systems. CDMA may be implemented in radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. The TDMA may be implemented in a wireless technology such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is part of E-UMTS (Evolved UMTS) using E-UTRA, adopts OFDMA in downlink and SC-FDMA in uplink. LTE-A (Advanced) is an evolved version of 3GPP LTE.

For clarity of description, 3GPP LTE / LTE-A is mainly described, but the technical idea of the present invention is not limited thereto. In addition, the specific terms used in the following description are provided to aid understanding of the present invention, and the use of such specific terms may be changed into other forms without departing from the technical idea of the present invention.

2 is a diagram showing a control plane and a user plane structure of a radio interface protocol between a UE and an E-UTRAN based on the 3GPP radio access network standard. The control plane refers to a path through which control messages used by a UE and a network are transferred. The user plane means a path through which data generated in the application layer, for example, voice data or Internet packet data, is transmitted.

The physical layer as the first layer provides an information transfer service to an upper layer using a physical channel. The physical layer is connected to the upper Medium Access Control layer through a transmission channel (Trans antenna Port Channel). Data moves between the MAC layer and the physical layer over the transport channel. Data is transferred between the transmitting side and the receiving side physical layer through the physical channel. The physical channel utilizes time and frequency as radio resources. Specifically, the physical channel is modulated in an OFDMA (Orthogonal Frequency Division Multiple Access) scheme in a downlink, and is modulated in an SC-FDMA (Single Carrier Frequency Division Multiple Access) scheme in an uplink.

The Medium Access Control (MAC) layer of the second layer provides a service to a radio link control (RLC) layer, which is an upper layer, through a logical channel. The RLC layer of the second layer supports reliable data transmission. The function of the RLC layer may be implemented as a functional block in the MAC. The Packet Data Convergence Protocol (PDCP) layer of the second layer performs a header compression function to reduce unnecessary control information in order to efficiently transmit IP packets such as IPv4 and IPv6 in a wireless interface with a narrow bandwidth.

The Radio Resource Control (RRC) layer located at the bottom of the third layer is defined only in the control plane. The RRC layer is responsible for the control of logical channels, transport channels and physical channels in connection with the configuration, re-configuration and release of radio bearers (RBs). RB denotes a service provided by the second layer for data transmission between the UE and the network. To this end, the terminal and the RRC layer of the network exchange RRC messages with each other. If there is an RRC connection (RRC Connected) between the UE and the RRC layer of the network, the UE is in the RRC Connected Mode, otherwise it is in the RRC Idle Mode. The Non-Access Stratum (NAS) layer at the top of the RRC layer performs functions such as session management and mobility management.

One cell constituting the base station eNB is set to one of the bandwidths of 1.4, 3, 5, 10, 15, and 20 MHz to provide downlink or uplink services to a plurality of UEs. Different cells may be set up to provide different bandwidths.

A downlink transmission channel for transmitting data from a network to a terminal includes a BCH (Broadcast Channel) for transmitting system information, a PCH (Paging Channel) for transmitting a paging message, a downlink SCH (Shared Channel) for transmitting user traffic or control messages, have. In case of a traffic or control message of a downlink multicast or broadcast service, it may be transmitted through a downlink SCH, or may be transmitted via a separate downlink multicast channel (MCH). Meanwhile, the uplink transmission channel for transmitting data from the UE to the network includes a random access channel (RACH) for transmitting an initial control message and an uplink SCH (shared channel) for transmitting user traffic or control messages. A logical channel mapped to a transport channel is a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH) Traffic Channel).

3 is a view for explaining a physical channel used in a 3GPP LTE system and a general signal transmission method using the same.

The user equipment that has been powered on again or has entered a new cell performs an initial cell search operation such as synchronizing with the base station in step S301. To this end, a user equipment receives a primary synchronization channel (P-SCH) and a secondary synchronization channel (S-SCH) from a base station, synchronizes with the base station, and acquires information such as a cell ID. Thereafter, the user equipment can receive the physical broadcast channel from the base station and obtain the in-cell broadcast information. Meanwhile, the UE may receive a downlink reference signal (DL RS) in an initial cell search step to check the downlink channel state.

Upon completion of the initial cell search, the user equipment receives a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Control Channel (PDSCH) according to physical downlink control channel information in step S302, Specific system information can be obtained.

Thereafter, the user equipment can perform a random access procedure such as steps S303 to S306 to complete the connection to the base station. To this end, the user equipment transmits a preamble through a physical random access channel (PRACH) (S303), and transmits a response to the preamble through the physical downlink control channel and the corresponding physical downlink shared channel Message (S304). In the case of a contention-based random access, a contention resolution procedure such as transmission of an additional physical random access channel (S305) and physical downlink control channel and corresponding physical downlink shared channel reception (S306) may be performed .

The user equipment having performed the procedure described above transmits a physical downlink control channel / physical downlink shared channel reception (S307) and a physical uplink shared channel (PUSCH) as general uplink / downlink signal transmission procedures, / Physical Uplink Control Channel (PUCCH) transmission (S308). The control information transmitted from the user equipment to the base station is collectively referred to as Uplink Control Information (UCI). The UCI includes HARQ ACK / NACK (Hybrid Automatic Repeat and Request Acknowledgment / Negative ACK), SR (Scheduling Request), CSI (Channel State Information) In this specification, HARQ ACK / NACK is simply referred to as HARQ-ACK or ACK / NACK (A / N). The HARQ-ACK includes at least one of positive ACK (simply ACK), negative ACK (NACK), DTX and NACK / DTX. The CSI includes a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), a Rank Indication (RI), and the like. The UCI is generally transmitted through the PUCCH, but may be transmitted via the PUSCH when the control information and the traffic data are to be simultaneously transmitted. In addition, UCI can be transmitted non-periodically through the PUSCH according to the request / instruction of the network.

4 is a diagram illustrating a structure of a radio frame used in an LTE system.

Referring to FIG. 4, in a cellular OFDM wireless packet communication system, uplink / downlink data packet transmission is performed on a subframe basis, and one subframe is defined as a predetermined time interval including a plurality of OFDM symbols . The 3GPP LTE standard supports a Type 1 radio frame structure applicable to Frequency Division Duplex (FDD) and a Type 2 radio frame structure applicable to TDD (Time Division Duplex).

4 (a) illustrates the structure of a Type 1 radio frame. A downlink radio frame is composed of 10 subframes, and one subframe is composed of two slots in a time domain. The time taken for one subframe to be transmitted is called a transmission time interval (TTI). For example, the length of one subframe may be 1 ms and the length of one slot may be 0.5 ms. One slot includes a plurality of OFDM symbols in the time domain and a plurality of resource blocks (RBs) in the frequency domain. In the 3GPP LTE system, since OFDMA is used in the downlink, an OFDM symbol represents one symbol period. The OFDM symbol may also be referred to as an SC-FDMA symbol or a symbol interval. A resource block (RB) as a resource allocation unit may include a plurality of continuous subcarriers in one slot.

The number of OFDM symbols included in one slot may vary according to the configuration of a CP (Cyclic Prefix). CP has an extended CP and a normal CP. For example, when an OFDM symbol is configured by a standard CP, the number of OFDM symbols included in one slot may be seven. When the OFDM symbol is configured by an extended CP, the length of one OFDM symbol is increased, so that the number of OFDM symbols included in one slot is smaller than that in the standard CP. In the case of the extended CP, for example, the number of OFDM symbols included in one slot may be six. If the channel condition is unstable, such as when the user equipment is moving at a high speed, an extended CP may be used to further reduce intersymbol interference.

One slot includes 7 OFDM symbols when a standard CP is used, so one subframe includes 14 OFDM symbols. At this time, the first three OFDM symbols at the beginning of each subframe may be allocated to a physical downlink control channel (PDCCH), and the remaining OFDM symbols may be allocated to a physical downlink shared channel (PDSCH).

4 (b) illustrates the structure of a Type 2 radio frame. The Type 2 radio frame is composed of two half frames, each of which has four general subframes including two slots, a Downlink Pilot Time Slot (DwPTS), a Guard Period (GP) And a special subframe including an uplink pilot time slot (UpPTS).

In this special subframe, the DwPTS is used for initial cell search, synchronization, or channel estimation in the user equipment. UpPTS is used to synchronize the channel estimation at the base station and the uplink transmission synchronization of the user equipment. That is, the DwPTS is used for downlink transmission and the UpPTS is used for uplink transmission. In particular, UpPTS is used for PRACH preamble or SRS transmission. Also, the guard interval is a period for eliminating the interference occurring in the uplink due to the multi-path delay of the downlink signal between the uplink and the downlink.

Regarding the special subframe, the setting is defined in the current 3GPP standard document as shown in Table 1 below. In Table 1, DwPTS and UpPTS are shown, and the remaining area is set as the guard interval.

[Table 1]

Meanwhile, Table 2 below shows the structure of the Type 2 radio frame, that is, the uplink / downlink subframe configuration (UL / DL configuration) in the TDD system.

[Table 2]

In Table 2, D denotes a downlink subframe, U denotes an uplink subframe, and S denotes the special subframe. Table 2 also shows the downlink-uplink switching period in the uplink / downlink subframe setup in each system.

The structure of the radio frame is merely an example, and the number of subframes included in a radio frame, the number of slots included in a subframe, and the number of symbols included in a slot can be changed variously.

FIG. 5 illustrates a resource grid for a downlink slot.

OFDM 심볼을 포함하고 주파수 영역에서

자원블록을 포함한다. 각각의 자원블록이

부반송파를 포함하므로 하향링크 슬롯은 주파수 영역에서

×

부반송파를 포함한다. 도 5는 하향링크 슬롯이 7 OFDM 심볼을 포함하고 자원블록이 12 부반송파를 포함하는 것으로 예시하고 있지만 반드시 이로 제한되는 것은 아니다. 예를 들어, 하향링크 슬롯에 포함되는 OFDM 심볼의 개수는 순환전치(Cyclic Prefix; CP)의 길이에 따라 변형될 수 있다. Referring to FIG. 5, the downlink slot is divided into time slots

OFDM symbols, and in the frequency domain

Resource block. Each resource block

Since the sub-carrier includes the sub-carrier, the down-

×

Subcarriers. 5 illustrates that the downlink slot includes 7 OFDM symbols and the resource block includes 12 subcarriers, but the present invention is not limited thereto. For example, the number of OFDM symbols included in the downlink slot may be modified according to the length of a cyclic prefix (CP).

×

자원요소로 구성되어 있다. 하향링크 슬롯에 포함되는 자원블록의 수(

)는 셀에서 설정되는 하향링크 전송 대역폭(bandwidth)에 종속한다. UL 슬롯의 구조는 DL 슬롯의 구조와 동일하되, OFDMA 심볼이 SC-FDMA 심볼로 대체된다.Each element on the resource grid is referred to as a resource element (RE), and one resource element is indicated by one OFDM symbol index and one subcarrier index. One RB

×

It consists of resource elements. The number of resource blocks included in the downlink slot (

) Is dependent on the downlink transmission bandwidth set in the cell. The structure of the UL slot is the same as that of the DL slot, but the OFDMA symbol is replaced with the SC-FDMA symbol.

6 illustrates the structure of a downlink sub-frame.

Referring to FIG. 6, a maximum of 3 (4) OFDM symbols located at the beginning of a first slot of a subframe corresponds to a control region to which a control channel is allocated. The remaining OFDM symbol corresponds to a data area to which PDSCH (Physical Downlink Shared Channel) is allocated. Examples of downlink control channels used in LTE include Physical Control Format Indicator Channel (PCFICH), Physical Downlink Control Channel (PDCCH), Physical Hybrid ARQ Indicator Channel (PHICH), and the like. The PCFICH carries information about the number of OFDM symbols transmitted in the first OFDM symbol of the subframe and used for transmission of the control channel in the subframe. The PHICH carries a HARQ ACK / NACK (Hybrid Automatic Repeat request acknowledgment / negative-acknowledgment) signal in response to the uplink transmission.

The control information transmitted through the PDCCH is referred to as DCI (Downlink Control Information). The DCI includes resource allocation information and other control information for the user equipment or user equipment group. For example, the DCI includes uplink / downlink scheduling information, uplink transmission (Tx) power control commands, and the like.

PDCCH includes a transmission format and resource allocation information of a downlink shared channel (DL-SCH), a transmission format and resource allocation information of an uplink shared channel (UL-SCH), a paging channel, Layer control message such as random access response transmitted on the PDSCH, Tx power control instruction set for individual user equipments in the user equipment group, Tx power < RTI ID = 0.0 > Control instructions, and information for activating Voice over IP (VoIP). A plurality of PDCCHs may be transmitted within the control domain. The user equipment can monitor a plurality of PDCCHs. The PDCCH is transmitted on an aggregation of one or a plurality of consecutive control channel elements (CCEs). The CCE is a logical allocation unit used to provide the PDCCH with a coding rate based on radio channel conditions. The CCE corresponds to a plurality of resource element groups (REG). The format of the PDCCH and the number of PDCCH bits are determined according to the number of CCEs. The base station determines the PDCCH format according to the DCI to be transmitted to the user equipment, and adds a CRC (cyclic redundancy check) to the control information. The CRC is masked with an identifier (e.g., radio network temporary identifier (RNTI)) according to the owner of the PDCCH or the purpose of use. For example, if the PDCCH is for a particular user equipment, the identifier of the user equipment (e.g., cell-RNTI (C-RNTI)) may be masked to the CRC. If the PDCCH is for a paging message, the paging identifier (e.g., paging-RNTI (P-RNTI)) may be masked to the CRC. If the PDCCH is for system information (more specifically, a system information block (SIC)), the system information RNTI (SI-RNTI) may be masked to the CRC. If the PDCCH is for a random access response, a random access-RNTI (RA-RNTI) may be masked in the CRC.

7 illustrates a structure of an uplink subframe used in LTE.

Referring to FIG. 7, the uplink subframe includes a plurality of (e.g., two) slots. The slot may include a different number of SC-FDMA symbols depending on the CP length. The UL subframe is divided into a data region and a control region in the frequency domain. The data area includes a PUSCH and is used to transmit a data signal such as voice. The control region includes a PUCCH and is used to transmit uplink control information (UCI). The PUCCH includes an RB pair (RB pair) located at both ends of the data area on the frequency axis and hopping the slot to the boundary.

The PUCCH may be used to transmit the following control information.

- SR (Scheduling Request): Information used for requesting uplink UL-SCH resources. OOK (On-Off Keying) method.

- HARQ ACK / NACK: This is a response signal to the downlink data packet on the PDSCH. Indicates whether the downlink data packet has been successfully received. In response to a single downlink codeword, one bit of ACK / NACK is transmitted and two bits of ACK / NACK are transmitted in response to two downlink codewords.

- CSI (Channel State Information): feedback information on the downlink channel. The CSI includes a CQI (Channel Quality Indicator), and feedback information related to Multiple Input Multiple Output (MIMO) includes a Rank Indicator (RI), a Precoding Matrix Indicator (PMI), and a Precoding Type Indicator (PTI). 20 bits per subframe are used.

The amount of control information (UCI) that the user equipment can transmit in the subframe depends on the number of SC-FDMAs available for control information transmission. The SC-FDMA available for transmission of control information means the remaining SC-FDMA symbol excluding the SC-FDMA symbol for reference signal transmission in the subframe. In the case of the subframe in which the SRS (Sounding Reference Signal) is set, SC-FDMA symbols are excluded. The reference signal is used for coherent detection of the PUCCH.

Hereinafter, HARQ (Hybrid Automatic Repeat and reQuest) in a wireless communication system will be described.

In a wireless communication system, when there are a plurality of terminals having data to be transmitted in the uplink / downlink, the base station selects a terminal to transmit data for each transmission time interval (TTI) (e.g., subframe). In particular, in a multi-carrier and similarly operated system, a base station selects terminals to transmit data in uplink / downlink for each transmission unit time, and also selects a frequency band used by each selected terminal for data transmission.

Referring to the uplink, the UEs transmit a reference signal (or pilot) in the uplink, and the BS determines the channel status of the UEs using the reference signal transmitted from the UEs, And selects the terminals to transmit data in the uplink in the band. The base station informs the terminal of the result. That is, the BS transmits an uplink allocation message to transmit data using a specific frequency band to a UE scheduled in a specific transmission unit time. The UL allocation message is also referred to as an UL grant. The UE transmits data on the uplink according to the uplink assignment message. The UL allocation message basically includes information on a UE ID, RB allocation information, payload, and the like, and may further include an Incremental Redundancy (IR) version, a New Data Indication (NDI) have.

When a synchronous non-adaptive HARQ scheme is applied, when a UE scheduled at a specific time retransmits, the retransmission time is systematically promised (e.g., after 4 subframes from the NACK reception time). Therefore, the UL grant message sent by the base station to the UE can be transmitted only during the initial transmission, and the subsequent retransmission is performed by the ACK / NACK signal. On the other hand, when the asynchronous adaptive HARQ scheme is applied, since the retransmission times are not agreed with each other, the BS must send a retransmission request message to the MS. In addition, since the frequency resource or MCS for retransmission is changed at each transmission time, the BS must transmit the HARQ process index, the IR version, and the NDI information together with the terminal ID, the RB allocation information, and the payload when transmitting the retransmission request message.

8 illustrates UL HARQ operation in an LTE system. In the LTE system, the UL HARQ scheme uses synchronous non-adaptive HARQ. When 8-channel HARQ is used, the HARQ process number is given as 0 to 7. One HARQ process operates per transmission time unit (e.g., subframe). Referring to FIG. 8, the BS 810 transmits an UL grant to the UE 820 through the PDCCH (S800). The UE 820 transmits the UL grant to the base station S810 using the RB and the MCS specified by the UL grant after 4 subframes (e.g., subframe 4) from the time when the UL grant is received (e.g., subframe 0) (S802). The base station 810 decodes the uplink data received from the UE 820 and generates an ACK / NACK. If the decoding of the uplink data fails, the base station 810 transmits a NACK to the terminal 820 (S804). The UE 820 retransmits the uplink data after four subframes from the reception of the NACK (S806). Here, the initial transmission and the retransmission of the uplink data are performed by the same HARQ processor (e.g., HARQ process 4).

9 shows an uplink transmission operation in the LTE-A system.

Currently, according to 3GPP TS 36.306 version 10.10.0, maximum performance is defined according to UE categories supported by LTE-A as follows.

[Table 3]

[Table 4]

Table 3 shows the maximum performance in the downlink, and Table 4 shows the maximum performance in the uplink. Describing with reference to Tables 3 and 4, in the case of the category 3, since the uplink is 50 Mbps, the downlink is 100 Mbps, and the category 4 is the uplink 150 Mbps and the downlink is 300 Mbps, Can be confirmed.

According to FIG. 9, according to the current standard specification, in order to transmit an uplink data packet, it is transferred from the TCP / IP layer to the LTE-A layer 2 (PDCP / RLC / MAC layer) And ciphering (encryption) to the MAC layer. The MAC layer transmits data according to the size of the uplink grant received from the base station, and the data that is not transmitted among the buffered data can be transmitted to the base station after receiving the uplink grant.

In this case, the TCP transmission unit controls the size of the transmission window through congestion control, and data can be transmitted without HARQ transmission / reception until a corresponding size. At this time, the maximum value of the transmission window size depends on the information transmitted from the receiver at the time of TCP connection. Since the bidirectional data transmission rate is unbalanced as described above, the wireless communication system such as the LTE-A has a large delay time compared with the data transmission rate, which can greatly affect the TCP performance depending on the transmission window size.

The maximum TCP transmission rate depends on the relationship as shown in Equation (1).

[Equation 1]

According to Equation (1), in order to satisfy the high downlink data performance, a large value of the TCP window size can be used. However, when TCP bidirectional communication is performed between the uplink and the downlink, an uplink transmission delay may be additionally generated due to a TPC ACK packet delay, which is a response message to downlink data, due to uplink data buffered in the MAC layer. Therefore, the downlink maximum TCP transmission rate may be lowered.

Since the maximum value of the data size to be buffered in the MAC layer is equal to the congestion window size of the uplink TCP transmission, the maximum value of the data size buffered in the MAC layer becomes equal to the size of the TCP receive window of the uplink reception side. Therefore, the relationship as shown in Equation (2) is satisfied.

&Quot; (2) "

According to Equation (2), in the bidirectional TCP communication, the downlink TCP performance may be degraded due to the uplink data rate and the transmission window size of the uplink receiver.

In such a case, an ACK packet delay and downlink TCP throughput degradation for the downlink TCP data occurs due to the buffering of the uplink TCP data packet, and a processing method for the TCP ACK packet in the uplink is required to prevent this .

10 is a flowchart illustrating a data transmission method in an uplink according to an embodiment of the present invention.

In the conventional system, since the data transmitted to the TCP layer is transmitted to the PDCP layer in the uplink data transmission, it has to be buffered from the base station to the point of transmission through the uplink grant. In this structure, even if it is desired to transmit the incoming data first, it is impossible to transmit the data because the already allocated sequence numbering and the ciphering using the number are performed.

In order to improve such a structure, the present invention proposes a method of adding a priority module 1000 for determining a priority between a TPC / TP layer and a PDCP layer as shown in FIG.

When the data is transmitted to the Transmission Control Protocol / Internet Protocol (TCP / IP) layer 1010, the priority module 1000 divides the data into a data packet and an acknowledgment packet, Is set lower than the priority order of the response packet (S1001).

After step S1001, the buffer size of the MAC layer is compared with a threshold value (S1003). If the buffer size is smaller than the threshold value, the PDCP layer 1020 transmits the data to the TCP / IP layer 1010.

When transferring the data to the TCP / IP layer 1010 to the PDCP layer 1020, the priority set in step S1001 is followed. The response packet is transmitted first according to the priority order (S1005), and only when the extra buffer size exists, the data packet can be transmitted (S1007).

In step S1005, the buffer size is smaller than the threshold according to the comparison result in step S1003. In this case, the size of the response packet transmitted may be smaller than the threshold value. Preferably, a response packet smaller than the remaining size excluding the buffer size at the threshold value may be transmitted.

The step S1007 can be performed only after the step S1005, when there is an extra data size. That is, the buffer size is excluded from the threshold value, and the data packet is transmitted by the size excluding the size of the response packet transmitted in step S1005.

Preferably, the threshold value is set considering a margin between the maximum UL transmission rate and a data processing rate in the PDCP layer, the RLC layer, and the MAC layer.

The data transmitted to the MAC layer receives the uplink grant from the base station and transmits the uplink data according to the grant (S1009).

As in the structure of FIG. 10 proposed in the present invention, a structure in which priority is given to a TCP ACK packet can prevent an uplink delay, which increases in a bidirectional TCP communication, compared to a one-way TCP communication method.

11, a wireless communication system includes a base station (BS) 1110 and a user equipment (UE) 1120. The base station 1110 includes a processor 1112, a memory 1114, and a radio frequency (RF) unit 1116. The processor 1112 may be configured to implement the procedures and / or methods suggested by the present invention. The memory 1114 is coupled to the processor 1112 and stores various information related to the operation of the processor 1112. [ The RF unit 1116 is coupled to the processor 1112 and transmits and / or receives wireless signals. The user equipment 1120 includes a processor 1122, a memory 1124, and an RF unit 1126. The processor 1122 may be configured to implement the procedures and / or methods suggested by the present invention. The memory 1124 is coupled to the processor 1122 and stores various information related to the operation of the processor 1122. [ The RF unit 1126 is coupled to the processor 1122 and transmits and / or receives radio signals. Base station 1110 and / or user equipment 1120 may have a single antenna or multiple antennas.

The embodiments described above are those in which the elements and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

Embodiments in accordance with the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) field programmable gate arrays, processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, a procedure, a function, or the like which performs the functions or operations described above. The software code can be stored in a memory unit and driven by the processor. The memory unit may be located inside or outside the processor and may exchange data with the processor by any of the already known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

1110:
1112: Processor
1114: Memory
1116: RF unit
1120: terminal
1122: Processor
1124: Memory
1126 RF unit

Claims (10)

In the uplink data transmission method,
Comparing the size of a buffer of the Medium Access Control (MAC) layer with a threshold value when the data is transmitted to a TCP / IP (Transmission Control Protocol / Internet Protocol) layer;
Transmitting the data transferred to the TCP / IP layer to a Packet Data Convergence Protocol (PDCP) layer when the buffer size is smaller than the threshold value; And
Transmitting uplink data transmitted to the MAC layer. The method according to claim 1,
The size of the data transmitted to the PDCP layer is,
Wherein the threshold is less than the difference between the threshold and the buffer size. The method according to claim 1,
When the data is transferred to the TCP / IP layer,
Dividing the data into a data packet and an acknowledgment packet, and setting a priority of the data packet to be lower than a priority of the response packet. The method of claim 3,
The step of transmitting the data to the PDCP layer comprises:
Wherein the response packet is delivered first according to the priority order, and the data packet is delivered only when an extra buffer size exists. The method according to claim 1,
The threshold value may be set to &
And setting a margin between a maximum UL transmission rate and a data processing rate in the PDCP layer, the RLC layer, and the MAC layer. In a terminal for uplink data transmission,
A radio frequency (RF) module; And
A process for controlling the radio frequency module,
The processor comprising:
When the buffer size of the Medium Access Control (MAC) layer is compared with a threshold value, if the buffer size is less than the threshold value, And transfers the data transferred to the TCP / IP layer to a Packet Data Convergence Protocol (PDCP) layer and uplinks the data transmitted to the MAC layer. The method according to claim 6,
The size of the data transmitted to the PDCP layer is,
Wherein the buffer size is smaller than the difference between the threshold value and the buffer size. The method according to claim 6,
The processor comprising:
And classifying the data into a data packet and an acknowledgment packet when the data is transmitted to the TCP / IP layer, and sets the priority of the data packet to be lower than the priority of the response packet. 9. The method of claim 8,
The processor comprising:
Wherein the response packet is delivered first according to the priority order, and the data packet is delivered only when an extra buffer size exists. The method according to claim 6,
The threshold value may be set to &
And a margin between a maximum UL transmission rate and a data processing rate in the PDCP layer, the RLC layer, and the MAC layer.

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