KR102075430B1 - Method and apparatus for downlink retransmission scheduling - Google Patents

Abstract

Provided are a method and an apparatus for scheduling downlink retransmission in a mobile communication system. The base station stores the type of downlink data transmitted and then receives feedback information from the terminal. When the type of transmitted downlink data corresponding to the received feedback information is a configuration type, retransmission scheduling is performed. When the type of the transmitted downlink data is not a configuration type, when a preset configuration condition is satisfied, retransmission scheduling is performed.

Description

Method and apparatus for downlink retransmission scheduling in a mobile communication system

The present invention relates to a method and an apparatus for scheduling downlink retransmission in a mobile communication system.

In a mobile communication system (eg, a long term evolution (LTE) system), a base station transmits downlink data through a downlink channel, that is, a physical downlink shared channel (PDSCH), and the terminal transmits a physical downlink shared channel (Physical). When successfully receiving the downlink shared channel (Feedback), a feedback of the hybrid automatic repeat reQuest (HARQ) acknowledgment (ACK), and if not successfully fed back feedback HARQ NACK (Negative ACK). The terminal transmits HARQ feedback according to downlink data reception through an uplink control channel, that is, a physical uplink control channel (PUCCH). The base station recognizes three states of ACK, negative ACK (NACK), and discontinuous transmission (DTX) for downlink data through the PUCCH. The ACK is a state in which data is received without a cyclic redundancy check (CRC) error, the NACK is a state in which a CRC error occurs, and the DTX is unable to determine an ACK / NACK because it does not detect a packet transmitted within an allotted time.

The base station may perform scheduling for a new downlink data transmission request when receiving HARQ ACK feedback for PDSCH transmission, and may perform scheduling for PDSCH retransmission when receiving HARQ NACK feedback.

In a time division duplex (LDD) LTE system, HARQ feedback for downlink transmission is a Physical Uplink Control Channel (PUCCH) format having HARQ-ACK bundling, HARQ-ACK multiplexing, and channel selection. ) 1b (PUCCH Format 1b with Channel Selection), PUCCH Format (Format) 3 and is reported in one of the HARQ mode of Special Bundling (Special Bundling).

The HARQ feedback according to the HARQ mode has a HARQ value corresponding to various states such as ACK, NACK, discontinuous transmission (DTX), ACK_OR_NACK, ACK_OR_DTX, ACK_OR_NACK_OR_DTX, and the like.

However, since a plurality of different states correspond to the same HARQ value, the BS may not know whether the UE has received the corresponding data using the HARQ value. Accordingly, even if the UE successfully receives data, for example, if the BS determined to be ACK_OR_NACK_OR_DTX as the HARQ feedback value performs retransmission for the maximum number of HARQ transmissions, waste of radio resources occurs and system performance is deteriorated. Occurs. In addition, even if the UE has not successfully received downlink data, if the base station determined as, for example, ACK_OR_NACK or ACK_OR_NACK_OR_DTX as the HARQ feedback value does not retransmit HARQ, error recovery fails with HARQ, and system performance is degraded. Problem occurs.

An object of the present invention is to provide a downlink retransmission scheduling method and apparatus for efficiently using radio resources and ensuring system performance in a mobile communication system.

According to an aspect of the present invention, a method for scheduling downlink retransmission includes: storing a type of downlink data transmitted; Receiving feedback information from a terminal; Performing retransmission scheduling when the type of transmitted downlink data corresponding to the received feedback information is a configuration type; Determining whether a preset setting condition is satisfied when the type of the transmitted downlink data is not a setting type; And when the setting condition is satisfied, performing retransmission scheduling.

According to an embodiment of the present invention, retransmission scheduling is performed according to the type of transmitted data and whether the setting condition is satisfied, thereby improving reliability of data transmission, preventing waste of radio resources due to unnecessary retransmission scheduling, and ensuring system performance. Can be.

1 is a flowchart of a downlink retransmission scheduling method according to a first embodiment of the present invention.
2 is a flowchart of a downlink retransmission scheduling method according to a second embodiment of the present invention.
3 is a flowchart of a downlink retransmission scheduling method according to a third embodiment of the present invention.
4 is a structural diagram of a retransmission scheduling apparatus according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, except to exclude other components unless specifically stated otherwise.

Throughout the specification, a terminal may include a user equipment (UE), a mobile station (MS), a mobile terminal (MT), an advanced mobile station (AMS), a high reliability mobile station. high reliability mobile station (HR-MS), subscriber station (SS), portable subscriber station (PSS), access terminal (AT), machine type communication device, MTC device) and the like, and may include all or a part of functions of the UE, MS, MT, AMS, HR-MS, SS, PSS, AT, and the like.

In addition, the base station (BS) is a node B (evolved node B, eNB), gNB, advanced base station (ABS), high reliability base station (high reliability base station, HR-BS), access point (AP), radio access station (RAS), base transceiver station (BTS), mobile multihop relay (BSR) -BS, repeater serving as a base station (relay station, RS), relay node (RN) serving as a base station, advanced relay station (ARS) serving as a base station, high reliability relay station serving as a base station , HR-RS), small base station (femto BS, home node B (HNB), home eNodeB (HeNB), pico base station (pico BS), macro base station (macro BS), micro base station ( micro BS), etc.), and all or one of NB, eNB, gNB, ABS, AP, RAS, BTS, MMR-BS, RS, RN, ARS, HR-RS, small base station, and the like. There's also an included feature.

Hereinafter, a method and apparatus for downlink retransmission scheduling according to an embodiment of the present invention will be described with reference to the accompanying drawings.

In a mobile communication system (e.g., long term evolution (LTE) system), in a time division duplex (TDD) system in an L1 application platform interface (API) defined by a standards-related organization (e.g., Small Cell Forum). (Hybrid Automatic Repeat reQuest (HARQ) feedback is reported as HARQ mode.) HARQ mode is HARQ-ACK bundling (named "bundling mode" for convenience of explanation), HARQ-ACK multiplexing (for convenience of description) PUCCH Format 1b with Channel Selection (PUCCH Format 1b with Channel Selection) for convenience of description, PUCCH format (named "multiplexing mode"), Format) 3 (named "Format 3 mode" for convenience of description) and Special Bundling (for example, refer to 3GPP TS 36.213 specification) In this TDD system, the HARQ reporting information is HARQ mode. , Acknowledgment (ACK) / NACK (Negative ACK) number, and includes each HARQ value (Value).

HARQ value may be defined as shown in Table 1 below.

Table 1 shows HARQ values in bundling mode, multiplexing mode, channel selection, and HARQ mode of format 3. In the HARQ value of Table 1, ACK_OR_NACK (3), ACK_OR_DTX (5), ACK_OR_NACK_OR_DTX (7) occurs in multiplexing mode or carrier aggregation (CA) of two carriers.

)을 획득할 수 있다. In a TDD system, a downlink subframe (DL subframe) and an uplink subframe (UL subframe) coexist in one radio frame, and M DL subframes may be connected to the UL subframe n. In this case, if M = 4, the UE may receive four PDCCHs from four DL subframes, and four PUCCH resources (eg,

) Can be obtained.

자원을 사용하여 b(0), b(1) 값으로 1, 0을 전송할 수 있다. 여기서, HARQ-ACK(i)는 4개의 DL 서브프레임 즉, 4개의 DL 할당 중 i번째 DL 할당에 대한 피드백 상태(ACK/NACK/DTX)를 나타낸다. b(0), b(1) 는 HARQ 피드백의 정보(ACK 또는 NACK 또는 DTX)를 나타내는 HARQ 피드백 값으로, 2 비트로 이루어질 수 있다. For example, in the HARQ multiplexing mode, the base station allocates four DL assignments to DL subframes for downlink data transmission, HARQ-ACK (0), HARQ-ACK (1), HARQ- ACK (2) When the HARQ-ACK (3) is ACK, ACK, ACK, DTX, respectively, the terminal is a predetermined resource allocated in the Physical Uplink Control Channel (PUCCH), for example,

The resource can be used to send 1 and 0 as b (0) and b (1) values. Here, HARQ-ACK (i) indicates a feedback state (ACK / NACK / DTX) for the i-th DL allocation of four DL subframes, that is, four DL allocations. b (0) and b (1) are HARQ feedback values indicating information (ACK or NACK or DTX) of HARQ feedback and may be composed of 2 bits.

자원을 통하여 단말로부터 전송된 2비트의 HARQ 피드백 값을 토대로 전송한 DL 할당에 대한 수신 성공 여부를 판단하는데, 동일한 HARQ 피드백 값에 대응하여 둘 이상의 서로 다른 피드백 상태가 대응될 수 있다. The base station

Determining whether reception of the DL allocation transmitted successfully is determined based on a 2-bit HARQ feedback value transmitted from the terminal through resources, and two or more different feedback states may correspond to the same HARQ feedback value.

Table 2 shows an example of a feedback state corresponding to the HARQ feedback value, and specifically, shows HARQ-ACK in downlink transmission in which M = 4.

The base station processes HARQ-ACK (0), HARQ-ACK (1), HARQ-ACK (2) and HARQ-ACK (3) as ACK, ACK, ACK_OR_NACK_OR_DTX, and ACK_OR_NACK_OR_DTX, as shown in Table 2. That is, when the values of b (0) and b (1) are "1, 0" according to Table 2, since different feedback states correspond, reception results of four DL subframes of the UE are ACK, ACK. , ACK, DTX, but the base station determines "ACK, ACK, ACK_OR_NACK_OR_DTX, ACK_OR_NACK_OR_DTX" according to the HARQ feedback value of "1, 0".

Accordingly, even though the terminal has successfully received the data and transmits the "ACK", it is determined that the base station is "ACK_OR_NACK_OR_DTX" to perform retransmission for the maximum number of HARQ transmissions. Accordingly, waste of radio resources may occur due to unnecessary retransmission, and system performance may be degraded.

자원을 사용하여 b(0), b(1) 값으로 1, 0을 전송한다. 이 경우, 기지국은 표 2에 따라, HARQ-ACK(0), HARQ-ACK(1), HARQ-ACK(2) HARQ-ACK(3)에 대해 ACK, ACK, ACK_OR_NACK_OR_DTX, ACK_OR_NACK_OR_DTX 로 처리한다.As another example, in the HARQ multiplexing mode, the base station allocates three DL assignments, and HARQ-ACK (0), HARQ-ACK (1), and HARQ-ACK (2) HARQ-ACK (3) transmitted from the UE are respectively If ACK, ACK, NACK, DTX,

Sends 1 and 0 as b (0) and b (1) values using resources. In this case, the base station processes the HARQ-ACK (0), HARQ-ACK (1), HARQ-ACK (2) HARQ-ACK (3) as ACK, ACK, ACK_OR_NACK_OR_DTX, ACK_OR_NACK_OR_DTX according to Table 2.

Therefore, even though the terminal does not receive data and transmits "NACK", the base station determines that "ACK_OR_NACK_OR_DTX" and may not perform HARQ retransmission. Accordingly, error recovery may fail with HARQ, and system performance may be degraded.

자원을 사용하여 b(0), b(1) 값으로 1, 0을 전송한다. As another example, in the PUCCH Format 1b with Channel Selection, the base station allocates four DL allocations to each of the primary cell and the secondary cell, and the terminal assigns four DL allocations to the primary cell. If all of the HARQ-ACK for each secondary cell is ACK,

Sends 1 and 0 as b (0) and b (1) values using resources.

The base station processes ACK, ACK_OR_DTX, ACK_OR_DTX, ACK_OR_DTX, ACK, ACK_OR_DTX, ACK_OR_DTX, and ACK_OR_DTX for HARQ-ACK of the primary cell and the secondary cell, respectively, according to Table 3 below.

The base station transmits four downlinks in the primary cell and the secondary cell, respectively, and the terminal successfully receives all eight downlink data according to the four downlink transmissions in each cell, thereby receiving b (0) and b ( 1) Although 1, 0 is transmitted as a value, the base station may process ACK, ACK_OR_DTX, ACK_OR_DTX, ACK_OR_DTX, ACK, ACK_OR_DTX, ACK_OR_DTX, and ACK_OR_DTX according to Table 3. Accordingly, the HARQ value is processed as ACK feedback for only one downlink transmission transmitted to each cell, and is processed as ACK_OR_DTX feedback for the remaining six downlink transmissions.

Although the terminal successfully receives, if the base station performs retransmission for the maximum number of HARQ transmissions for the downlink transmission processed by the ACK_OR_DTX feedback, the waste of radio resources may occur seriously and the system performance may be drastically degraded.

자원을 사용하여 b(0), b(1) 값으로 0, 0을 전송한다. 이 때, 기지국에서는 표 4에 따라 1차 셀과 2차 셀의 HARQ-ACK를 판단한다. In another example, in the channel selection mode (PUCCH Format 1b with Channel Selection), the base station allocates four DL assignments to the primary cell and the secondary cell, respectively, HARQ for each of the primary cell and the secondary cell at the terminal If -ACK is all NACK,

Sends 0 and 0 as values of b (0) and b (1) using resources. At this time, the base station determines the HARQ-ACK of the primary cell and the secondary cell according to Table 4.

The base station transmits four downlinks in the primary cell and the secondary cell, respectively, and the terminal does not successfully receive eight downlink data according to the four downlink transmissions in each cell, so that b (0) and b ( 1) Although the base station transmits 0 and 0 as values, the base station considers four states corresponding to the values of 0 and 0 according to Table 4, respectively, for the HARQ-ACK of the primary cell and the secondary cell, respectively, ACK_OR_NACK. Process as ACK_OR_NACK_OR_DTX, ACK_OR_NACK_OR_DTX, ACK_OR_NACK_OR_DTX, ACK_OR_NACK_OR_DTX, ACK_OR_NACK_OR_DTX, ACK_OR_NACK_OR_DTX.

If the UE has not successfully received downlink data, but the base station that receives the ACK_OR_NACK or ACK_OR_NACK_OR_DTX as the HARQ feedback value does not retransmit the HARQ, error recovery fails with HARQ, resulting in a problem of degrading system performance.

Meanwhile, when the terminal simultaneously transmits HARQ feedback and scheduling request (SR), the number of ACKs is reported as shown in Table 5 using the special bundling mode.

Table 5 shows HARQ values in the special bundling mode.

For example, in the special bundling mode, when four DL assignments are used and only three DL assignments are ACK, the UE reports HARQ value 3. The base station only recognizes that only three of the four DL allocations have been successfully received from Table 5 according to HARQ value 3, and the three DL allocations successfully received by the UE in the four DL allocations and the DL allocations that were not successfully received 1 Can't distinguish dogs Accordingly, if the base station performs retransmission for the maximum number of HARQ transmissions for the four DL allocations, there is a problem that waste of radio resources occurs and system performance is drastically degraded.

Therefore, in such a system in which HARQ feedback information indicates a plurality of HARQ values, there is a need for a downlink retransmission scheduling method for efficiently using radio resources and ensuring system performance.

In an embodiment of the present invention, data retransmission is performed according to a data type corresponding to feedback information. Specifically, when the base station transmits the initial data, the data type to be transmitted is set and stored, and when the data type corresponding to the feedback information received from the terminal is a preset data type, retransmission is performed and the data type is preset If it is not a data type, retransmission is performed depending on whether the set condition is satisfied. This processing may be performed when it is not possible to clearly determine whether the feedback information received from the terminal is ACK or NACK or DTX.

To this end, when the base station transmits initial data with DL allocation to the terminal (also called HARQ new transmission), the base station stores the type of transmitted data. Data transmitted according to the DL allocation may be transmitted in units of TBs, and the base station confirms the type for each data transmitted in units of TB, generates, stores, and manages the transmitted data list information. The transmitted data list information includes type information for each data transmitted in units of TB.

The data type may include signaling data, radio link control (RLC) acknowledged mode (AMLC) data (referred to as "AM data" for convenience of description), and padding data. The signaling data includes bearer data or media access control (MAC) control elements set to quality control indicator (QCI) 5 for transmitting signaling radio bearer (SRB) data or IP multimedia subsystem (IMS) signaling. .

When data transmitted in TB units does not include data other than padding, the type of the data is classified as padding data. For example, when the transmission mode of the terminal is capable of transmitting two TBs simultaneously in one subframe, and the TB size is allocated but there is no more data to be transmitted in the buffer, the padding data may be transmitted.

In the case of AM data, since it is transmitted in the RLC layer, the transmitted data list information may further include a logical channel identifier and a sequence number.

In an embodiment of the present invention, the base station transmits downlink data in TB units for the terminal, and then receives HARQ feedback for such data. For convenience of description, the transmission of downlink data in units of TB is referred to as "transmitting downlink (DL) assignment." The base station transmits a DL allocation and receives HARQ feedback for the DL allocation transmitted after HARQ round trip time (RTT).

The base station selects the DL allocation information transmitted to the serving cell based on the retransmission scheduling wait list of the serving cell of the terminal based on the HARQ feedback information received for the DL allocation of the terminal transmitted to the serving cell of the terminal in subframe n. To add. In addition, when the base station does not receive HARQ feedback on the DL allocation transmitted to the serving cell of the terminal in subframe n, the base station adds DL allocation information transmitted to the serving cell to the retransmission scheduling wait list of the serving cell of the terminal. . Adding the transmitted DL allocation information to the retransmission scheduling wait list of the serving cell of the terminal and allocating resources for retransmission scheduling thereafter is called "retransmission scheduling" for convenience of description.

In the scheduling subframe, when information exists in the retransmission scheduling wait list in the terminal to be scheduled and the serving cell to be scheduled, the retransmission scheduling for the DL allocation information in front of the retransmission scheduling wait list in the serving cell of the terminal is performed. Retransmission is performed by performing radio resource allocation, and then, the corresponding DL allocation information is deleted from the retransmission scheduling list of the serving cell of the terminal.

First, a downlink retransmission scheduling method according to a first embodiment of the present invention will be described.

1 is a flowchart of a downlink retransmission scheduling method according to a first embodiment of the present invention.

When the base station transmits initial data by DL allocation to the terminal, the base station checks the type for each data transmitted in units of TB and stores the type in the data list information (S100). Type information is stored in the data list information corresponding to data transmitted in units of TB, and in particular, the timing of the transmitted data is mapped and stored.

The base station transmits data, ie DL allocation, to the serving cell of the terminal (S110). The order in which the data type storing step and the DL allocation transmitting step are performed is not limited thereto, and may be changed.

Thereafter, the base station receives the HARQ feedback for the transmitted DL allocation (S120).

The base station determines the type of data transmitted by the DL allocation corresponding to the received HARQ feedback. The HARQ feedback includes a case in which no ACK feedback is received (S140).

The base station does not perform retransmission scheduling when the type of the determined data is a setting type, that is, padding data (S150).

On the other hand, if the type of the determined data is not the padding data, the base station additionally determines whether the set condition is satisfied (S160). Here, the setting condition is that the number of HARQ transmissions of data transmitted by DL allocation does not exceed the maximum number of HARQ transmissions, and may be referred to as a first setting condition. If the type of data is not padding data and the first setting condition is satisfied, the base station performs retransmission scheduling (S170). That is, the DL allocation is added to the retransmission scheduling wait list of the terminal to be retransmitted. On the other hand, if the type of data is not padding data but the first setting condition is not satisfied, retransmission scheduling is not performed.

As described above, in the first embodiment of the present invention, since retransmission scheduling is not performed when the transmitted data type is padding data, unnecessary resource waste can be prevented.

Next, a downlink retransmission scheduling method according to a second embodiment of the present invention will be described.

In a second embodiment of the present invention, the HARQ feedback mode is a bundling mode (HARQ-ACK Bundling), a multiplexing mode (HARQ-ACK Multiplexing), a channel selection mode (PUCCH Format 1b with Channel Selection), a format 3 mode (PUCCH Format 3) ), Retransmission scheduling is performed according to the HARQ value.

2 is a flowchart of a downlink retransmission scheduling method according to a second embodiment of the present invention.

When the base station transmits initial data by DL allocation to the terminal, the base station checks the type for each data transmitted in units of TB and stores the type in the data list information (S300).

The base station transmits data, that is, DL allocation, to the serving cell of the terminal (S310). The order in which the data type storing step and the DL allocation transmitting step are performed is not limited thereto, and may be changed.

Then, the base station receives the HARQ feedback for the transmitted DL allocation (S320). In this case, since the HARQ feedback mode is one of a bundling mode, a multiplexing mode, a channel selection mode, and a format 3 mode, the HARQ feedback mode is used to receive the HARQ value.

The base station determines the state of the ACK or NACK or DTX for the DL allocation based on the received HARQ value. If it is not possible to clearly determine the state of the ACK or NACK or DTX from the received HARQ value (S330), the base station adds the DL allocation to the retransmission scheduling wait list of the terminal for retransmission processing.

In this case, when the base station cannot clearly determine the state of the ACK or the NACK or the DTX, the base station includes at least one meaning of NACK or DTX as one of a preset first state, for example, NACK, ACK_OR_NACK, DTX, NACK_OR_DTX, and ACK_OR_NACK_OR_DTX. In this case, the DL allocation is added to the retransmission scheduling wait list of the terminal for retransmission processing (S340 and S350).

However, when the base station cannot clearly identify the state of the ACK or the NACK or the DTX, the second state is determined in advance, for example, ACK_OR_DTX. If the type of the determined data is a configuration type, that is, signaling data, the base station performs retransmission scheduling (S350).

On the other hand, when the state confirmed from the received HARQ value is the second state ACK_OR_DTX and the data type of the corresponding DL allocation is not the signaling data, it determines whether the setting condition is satisfied (S370). Herein, the setting condition indicates that a block error rate (BLER) of the serving cell of the terminal is higher than a preset reference value, and may be referred to as a second setting condition. The preset reference value may be set to a low value such as 1/100, and the lower the reference value may increase the data transmission reliability of the system. Here, if the second setting condition is satisfied, retransmission scheduling is performed (S350).

On the other hand, if the state confirmed from the received HARQ value is the second state ACK_OR_DTX, and the data type of the corresponding DL allocation is not the signaling data, the base station does not perform retransmission scheduling (S380). ).

According to the second embodiment of the present invention, when the HARQ value includes at least one of NACK or DTX meaning, by performing retransmission scheduling, error recovery can be performed by HARQ retransmission and reliability of data transmission can be improved.

In addition, when the HARQ value is ACK_OR_DTX, when the BLER of the serving cell of the UE is higher than the reference value, retransmission scheduling may be performed to enable error recovery by HARQ retransmission. In this case, when the BLER of the serving cell of the terminal is lower than the reference value, the retransmission scheduling is not performed. Therefore, it is possible to solve the problem of wasting radio resources and causing system performance degradation due to unnecessary retransmission.

In addition, when the HARQ value is ACK_OR_DTX, when the transmitted data includes signaling data having a high priority, retransmission scheduling may be performed to increase the reliability of signaling data transmission.

Next, a downlink retransmission scheduling method according to a third embodiment of the present invention will be described.

In the third embodiment of the present invention, retransmission scheduling is performed when the HARQ feedback mode is a special bundling mode. In the special bundling mode, the UE reports the number of ACKs, and the HARQ value indicates the number of ACKs as shown in Table 5 above.

3 is a flowchart of a downlink retransmission scheduling method according to a third embodiment of the present invention.

When the base station transmits initial data by DL allocation to the terminal, the base station checks the type for each data transmitted in units of TB and stores the type in the data list information (S500).

The base station transmits data, that is, DL allocation, to the serving cell of the terminal (S510). The order in which the data type storing step and the DL allocation transmitting step are performed is not limited thereto, and may be changed.

Thereafter, the base station receives the HARQ feedback for the transmitted DL allocation (S520). At this time, since the HARQ feedback mode is a special bundling mode, the HARQ feedback mode receives a HARQ value indicating the number of ACKs.

If the total number of DL allocations transmitted to all serving cells is not mapped to the HARQ value (Value 0) received in the special bundling mode, that is, based on the received HARQ value, that is, the base station determines in each serving cell from the received HARQ value. If the number of successfully allocated DL allocations cannot be determined or the terminal cannot successfully distinguish DL allocation information received from a plurality of DL allocations, the type of transmitted data is determined (S530 and S540). The base station performs retransmission scheduling when the determined data type is a configuration type, that is, signaling data (S550 and S560).

On the other hand, if the total number of DL allocations transmitted to all serving cells is not mapped to the HARQ value (Value 0) received in the special bundling mode, if the determined data type is not signaling data, is the setting condition satisfied? Determine (S570). Herein, the setting condition indicates that the BLER of all the serving cells of the terminal is higher than a preset reference value and may be called a third setting condition. At this time, if the third setting condition is satisfied, retransmission scheduling is performed (S560). If the third setting condition is not satisfied, retransmission scheduling is not performed (S580).

According to the third embodiment of the present invention, in the HARQ feedback mode, which is a special bundling mode, the number of DL allocations successfully received by each serving cell cannot be determined, or DL allocation information successfully received by the UE from among a plurality of DL allocations can be determined. When not distinguishable, when the BLER of all the serving cells of the terminal is higher than a predetermined reference value, by performing retransmission scheduling, error recovery can be performed by HARQ retransmission, and the BLER of all the serving cells of the terminal is lower than a predetermined reference value. Since no retransmission scheduling is performed, the problem that causes system performance deterioration due to unnecessary retransmissions can be solved.

In addition, in the third embodiment of the present invention, when the number of DL allocations successfully received in each serving cell in the special bundling mode cannot be confirmed or the DL allocation information successfully received by the UE among a plurality of DL allocations cannot be distinguished. If the data transmitted by DL allocation includes signaling data with high priority, the reliability of signaling data transmission can be improved by performing retransmission scheduling.

On the other hand, in one embodiment of the present invention, when the base station transmits the initial data by the DL allocation for the terminal, the base station checks the type for each data transmitted in units of TB and stores the type in the data list information. In the case where the data is AM data, the data list information includes a logical channel identifier and a sequence number. Since the data is transmitted through the RLC layer, the terminal receives the RLC STATUS PDU transmitted after the transmission. If the state information is PACK (Positive ACK), the state of the data is set to PACK corresponding to the logical channel identifier and the sequence number of the data. Thus, for AM data transmission, the data list information includes the data type, logical channel identifier and sequence number, and data state (PACK or NACK).

After data transmission, the base station performs retransmission scheduling on the AM data based on the data list information. Among the DL allocations included in the retransmission scheduling wait list of the serving cell of the terminal for retransmission processing, when the transmitted data type is AM data and each data state of the data list information is PACK, the corresponding retransmission scheduling wait list is applied. Delete the DL allocation information.

According to the embodiments of the present invention as described above, when the HARQ feedback for the DL allocation is not known whether the ACK, NACK or DTX state (HARQ value indicates a plurality of meanings such as ACK_OR_NACK, ACK_OR_NACK_OR_DTX or special bundling In case the DL allocation information successfully received by the UE cannot be distinguished according to the value received in the mode (value0), retransmission scheduling of the transmitted TB is performed to increase the reliability of data transmission, and in particular, the type of the transmitted data Retransmission scheduling is selectively performed according to the < RTI ID = 0.0 > and, < / RTI > when information successfully receiving data is confirmed by the RLC STATUS PDU transmitted by the UE, the allocation information of the corresponding data is deleted from the retransmission scheduling wait list, resulting in unnecessary retransmission scheduling. It can prevent radio resource waste and ensure system performance. Therefore, according to embodiments of the present invention, by performing retransmission scheduling based on HARQ feedback information and BLER of the serving cell of the terminal and / or type information of the transmitted data, guaranteeing the transmission reliability of the data, by unnecessary retransmission It can prevent radio resource waste and ensure system performance.

4 is a structural diagram of a retransmission scheduling apparatus according to an embodiment of the present invention.

As shown in FIG. 4, a retransmission scheduling apparatus 100 according to an embodiment of the present invention includes a processor 110, a memory 120, and a transceiver 130. The processor 110 may be configured to implement the method described based on FIGS. 1 to 3 above. Detailed description of parts similar to the above method is omitted here.

To this end, the processor 110 includes a data transmission processor 111, a HARQ feedback processor 112, and a retransmission resource allocation processor 113.

The data transmission processor 111 is configured to transmit data through the transceiver 130 in units of TB by DL allocation of the terminal, and is configured to manage the transmitted data type through data list information.

The HARQ feedback processor 112 determines whether the terminal receives data based on the HARQ feedback information received through the transceiver 130, and if the data type is unknown from the HARQ feedback information, the transmitted data type is a setting type. It is configured to selectively perform the retransmission scheduling process (adding the corresponding data to the transmission waiting list of the serving cell of the terminal) only if it corresponds to. In addition, the HARQ feedback processing unit 112 is configured to perform the retransmission scheduling process depending on whether a setting condition (first to third setting conditions) is satisfied when it is not known whether data is received from the HARQ feedback information.

The retransmission resource allocation processing unit 113 is configured to allocate radio resources for retransmission scheduling with respect to DL allocation information included in the transmission waiting list of the serving cell of the terminal. In addition, the retransmission resource allocation processing unit 113 deletes the information from the transmission waiting list for the DL allocation to which the radio resource for retransmission scheduling has been allocated. In particular, the retransmission resource allocation processing unit 113 is a retransmission scheduling wait list in the retransmission scheduling wait list of the serving cell of the terminal when the data type transmitted by DL allocation is AM data and each data state of the data list information is PACK. Is configured to delete the corresponding DL allocation information.

The memory 120 is connected to the processor 110 and stores various information related to the operation of the processor 110. The memory 120 may be located inside or outside the processor, and the memory may be connected to the processor through various known means. Memory is various forms of volatile or nonvolatile storage media, for example, the memory may include read-only memory (ROM) or random access memory (RAM).

The transceiver 130 is connected to the processor 110 and transmits or receives a radio signal.

An embodiment of the present invention is not implemented only through the above-described apparatus and / or method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention, a recording medium on which the program is recorded, and the like. The implementation may be easily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (13)

delete Receiving feedback information from the terminal after transmitting downlink data to the terminal;
Comparing the type of the transmitted downlink data corresponding to the received feedback information with a preset type;
Determining whether a preset setting condition is satisfied; And
Performing retransmission scheduling based on at least one of the type comparison result and a result of whether the set condition is satisfied;
Including,
Before or after receiving the feedback information,
Storing a type of downlink data transmitted to the terminal
Retransmission scheduling method further comprising. The method of claim 2,
The step of storing the type,
The transmitted downlink data is transmitted in units of transport blocks, and stores type information corresponding to the data transmitted in units of transport blocks.
Wherein the type of data is one of signaling data, radio link control (RLC) acknowledged mode (AML) data, padding data. Receiving feedback information from the terminal after transmitting downlink data to the terminal;
Comparing the type of the transmitted downlink data corresponding to the received feedback information with a preset type;
Determining whether a preset setting condition is satisfied; And
Performing retransmission scheduling based on at least one of the type comparison result and a result of whether the set condition is satisfied;
Including,
After receiving feedback information from the terminal,
Determining whether a state determined according to the feedback information is a setting state
More,
The comparing may include comparing the type of the transmitted downlink data and the preset type when the determined state is a setting state. The method of claim 4, wherein
And performing retransmission scheduling comprises performing retransmission scheduling when the type of the transmitted downlink data is signaling data. The method of claim 4, wherein
The comparing may include: when the state indicating whether the terminal receives data determined according to the feedback information is a setting state including two states of ACK (Acknowledgement) and discontinuous transmission (DTX), Retransmission scheduling method for comparing with the preset type. The method of claim 6,
Performing the retransmission scheduling,
And performing retransmission scheduling when the type of the transmitted downlink data is not signaling data and a block error rate (BLER) of a serving cell of the terminal is higher than a preset reference value. The method of claim 4, wherein
Feedback mode is a special bundling mode, the feedback information includes a value indicating the number of ACK,
The comparing may include determining that the state determined according to the feedback information cannot determine the number of data in units of transport blocks successfully received by the terminal or that the terminal has successfully received data among units of transport blocks. And reconfiguring the data in units of transport blocks, and comparing the type of the data with the preset type. The method of claim 8,
Performing the retransmission scheduling,
And performing retransmission scheduling when the type of the transmitted downlink data is not signaling data and the BLERs of all the serving cells of the terminal are higher than a preset reference value. The method of claim 2,
Performing the retransmission scheduling,
Performing retransmission scheduling when the type of the transmitted downlink data is not padding data and the number of retransmissions does not exceed the maximum number of transmissions; And
Retransmission scheduling is not performed if the type of the transmitted downlink data is padding data
Retransmission scheduling method comprising a. The method of claim 3,
The step of storing the type,
When the type of the downlink data transmitted is AM data, data list information including a data type, a logical channel identifier, and a sequence number is stored;
And storing a data state of PACK (Positive ACK) or NACK (Negative ACK) in the data list information according to the state information included in the received feedback information. The method of claim 11,
Performing the retransmission scheduling,
As a result of the type comparison, when the type of the downlink data transmitted is AM data, the transmitted data type is AM data among DL (downlink) allocations included in the retransmission scheduling wait list of the serving cell of the terminal. A retransmission scheduling method for deleting DL allocation information in which each data state of the information is all PACK. The method according to claim 4 or 8,
If the determined state is a setting state,
The comparing may include comparing the type of the transmitted downlink data with the preset type,
In the determining of whether the preset setting condition is satisfied, comparing the BLER of the serving cell of the terminal with a preset BLER
Retransmission Scheduling Method

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