KR102149000B1 - Method for transmitting data - Google Patents

Abstract

The data transmission method of the embodiment is the step of determining whether HARQ ((Hybrid Automatic Retransmit reQuest) feedback) from at least one user equipment is received, and when HARQ feedback is received, the number of transport blocks of the user equipment corresponding to the HARQ feedback Setting and setting the number of ACK (ACKnowledge) and NACK (Negative-ACKnowledge) by reflecting the block error ratio according to the value of HARQ feedback, and updating the block error ratio of each of at least one user equipment Includes steps.

Description

Data transfer method {METHOD FOR TRANSMITTING DATA}

The present disclosure relates to a technology for providing data transmission, and more particularly, to a method for transmitting data using wireless communication.

In the Long Term Evolution (LTE) system, the Modulation and Coding Scheme (MCS) used by the Physical Downlink Shared Channel is a channel quality indicator (CQI) transmitted by the user equipment. It can be determined according to the state of the network based on.

If the network is in good condition, the process of modulating and encrypting data to increase the data rate can be simplified, and if the network condition is bad, the process of modulation and encryption to increase the reception rate of data may increase. .

The embodiments are for properly adjusting a block error ratio (BLER).

Further, the embodiments are for improving the performance of the data transmission system.

According to an embodiment of the present invention, the data transmission method includes determining whether or not HARQ ((Hybrid Automatic Retransmit request) feedback) from at least one user equipment is received, when HARQ feedback is received, a user corresponding to the HARQ feedback Setting the number of transport blocks of the device, and setting the number of ACK (ACKnowledge) and NACK (Negative-ACKnowledge) by reflecting the block error ratio according to the value of HARQ feedback, and at least one user equipment. And updating the block error rate.

According to the embodiment, there is an advantage of ensuring the performance of the data transmission system.

In addition, according to the embodiment, there is an advantage of ensuring a target block error rate.

1 is an exemplary diagram illustrating an example of a data transmission system.
2 is a block diagram of a data transmission device according to an embodiment.
3 is a flowchart of a data transmission method according to an embodiment.
4 is a flowchart of a method of setting the number of ACKs and the number of NACKs of a serving cell according to an embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the embodiments of the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and similar reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, user equipment (UE) is a terminal, a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), and a highly reliable mobile station ( High reliability mobile station (HR-MS), subscriber station (SS), portable subscriber station (PSS), access terminal (AT), etc., and terminal, MT, AMS , HR-MS, SS, PSS, AT, may include all or part of the functions such as UE.

In addition, the base station (BS) is an advanced base station (ABS), a high reliability base station (HR-BS), a node B (node B), an advanced node B (evolved node B), eNodeB), access point (AP), radio access station (RAS), base transceiver station (BTS), mobile multihop relay (MMR)-BS, relay serving as a base station station, RS), and a high reliability relay station (HR-RS) that serves as a base station, and ABS, NodeB, eNodeB, AP, RAS, BTS, MMR-BS, RS, HR -It may include all or part of functions such as RS.

1 is an exemplary diagram illustrating an example of a data transmission system.

The data transmission system 100 includes a base station 110 for transmitting data and a user equipment 120 for receiving data.

According to one aspect, the base station 110 uses an LTE-Advanced (LTE-A) system developed by a 3rd Generation Partnership Project Long Term Evolution Rel-8 (LTE) system. Data can be transmitted. The LTR-A system uses component carrier aggregation technology to extend bandwidth. For example, the LTE-A system can support a total of 100 MHz bandwidth by combining five bandwidths of 20 MHz. The LTE-A system may include an entity that processes a hybrid automatic retransmit request (HARQ) according to each carrier. Since the HARQ entity exists for each carrier, the LTE-A system can support carrier aggregation. It has been described that the base station 110 uses the LTE-A system, but there is no limitation in the communication system applied to the base station 110.

User equipment 120 may receive data from base station 110. For example, the user equipment 120 may receive data transmitted through each carrier. When receiving data, the user equipment 120 may transmit an ACK (ACKnowledge) feedback to the base station 110. The user equipment 120 may transmit negative-ACKnowledge (NACK) feedback to the base station 110 when data is not received.

The user equipment 120 may transmit information indicating the channel quality between the base station 110 and the user equipment 120 to the base station 110. For example, the user equipment 120 may periodically transmit data including a channel quality indicator (CQI) to the base station 110.

The base station 110 may transmit the modulated and encrypted data to the user equipment 120 by applying the determined Modulation and Coding Scheme (MCS) to the data. The MCS applied to the data may be determined based on at least one of HARQ feedback and channel quality of the user equipment 120. The higher the HARQ feedback and the better the channel quality, the higher the degree of modulation and encryption, and when a high MCS is applied to data, the data rate may increase.

Next, referring to FIG. 2, a data transmission apparatus according to an embodiment, that is, the base station 110 will be described in detail.

2 is a block diagram of a data transmission device according to an embodiment. As shown in FIG. 2, the data transmission device 200 includes a communication unit 210, a base station 220, and a memory 230.

The communication unit 210 transmits and receives data to and from external user equipment. For example, the communication unit 210 may receive data from user equipments 120 around the data transmission device 200 and transmit data to the user equipments 120. The base station 220 processes data received by the communication unit 210 and data stored in the memory 230.

The memory 230 stores data received by the communication unit 210 and data processed by the base station 220.

On the other hand, in the LTE system of the TDD scheme, HARQ feedback for downlink transmission is a HARQ-ACK bundling (HARQ-ACK Bundling) mode, a HARQ-ACK multiplexing mode, a channel selection using PUCCH format 1b (PUCCH It is reported to the base station 110 in one of a format 1b with channel selection) mode, a PUCCH format 3 mode, and a special bundling mode.

The HARQ report information includes a HARQ mode, the number of ACK/NACKs, and each HARQ value, and the HARQ value may be defined as shown in Tables 1 and 2 below according to the HARQ mode.

Field Type Description Value 0 uint8_t 1 = ACK
2 = NACK
3 = ACK or NACK
4 = DTX
5 = ACK or DTX
6 = NACK or DTX
7 = ACK or NACK or DTX

Field Type Description Value 0 uint8_t 0 = 0 or None (UE detect at least one DL assignment is missed)
1 = 1 or 4 or 7 ACKs reported
2 = 2 or 5 or 8 ACKs reported
3 = 3 or 6 or 9 ACKs reported
4 = DTX (UE did not transmit anything)

Among the HARQ values (HARQ values (value 0)) of Table 1, ACK_OR_NACK(3), ACK_OR_DTX(5), and ACK_OR_NACK_OR_DTX(7) may be generated in HARQ multiplexing mode or carrier aggregation of two carriers.

For example, according to Table 3 below in the HARQ multiplexing mode, the base station 110 allocates three downlink assignments. User equipment 120 uses the resources when the received HARQ-ACK (0), HARQ-ACK (1), HARQ-ACK (2) HARQ-ACK (3) is ACK, ACK, ACK, DTX, respectively, and b 1 and 0 are transmitted to the base station 110 as values of (0) and b(1). The base station 110 processes ACK, ACK, ACK_OR_NACK_OR_DTX, ACK_OR_NACK_OR_DTX for HARQ-ACK (0), HARQ-ACK (1), HARQ-ACK (2) and HARQ-ACK (3) according to Table 3.

HARQ - ACK (0), HARQ - ACK (One), HARQ - ACK (2), HARQ - ACK (3) Resource b(0), b(1) ACK, ACK, ACK, NACK/DTX

1, 0 ACK, ACK, NACK/DTX, ACK

1, 0

As another example, in the channel selection mode using PUCCH format 1b, the base station 110 allocates four downlink allocations to each of a primary cell and a secondary cell according to Table 4 below. When the HARQ-ACK for each of the primary cell and the secondary cell is ACK, the user equipment 120 transmits 1 and 0 as values of b(0) and b(1) to the base station 110 using resources. . The base station 110 processes HARQ-ACK of the primary cell and the secondary cell as ACK, ACK_OR_DTX, ACK_OR_DTX, ACK_OR_DTX, ACK, ACK_OR_DTX, ACK_OR_DTX, ACK_OR_DTX, respectively, according to Table 3.

Primary Cell Secondary Cell Resource Constellation RM Code
Input Bits HARQ - ACK (0), HARQ-ACK (1), HARQ-ACK (2), HARQ-ACK (3) HARQ - ACK (0), HARQ-ACK (1), HARQ-ACK (2), HARQ-ACK (3)

b(0), b(1) o(0), o(1), o(2), o(3) ACK, DTX, DTX, DTX ACK, DTX, DTX, DTX

1, 0 0, 1, 0, 1 ACK, DTX, DTX, DTX ACK, ACK, ACK, ACK

1, 0 0, 1, 0, 1 ACK, ACK, ACK, ACK ACK, DTX, DTX, DTX

1, 0 0, 1, 0, 1 ACK, ACK, ACK, ACK ACK, ACK, ACK, ACK

1, 0 0, 1, 0, 1

In this way, in the LTE system of the TDD scheme, among the HARQ values (HARQ values (value 0)) of Table 1, HARQ values indicating a plurality of feedback information, such as ACK_OR_NACK(3), ACK_OR_DTX(5), and ACK_OR_NACK_OR_DTX(7), are provided. There is a case of receiving.

In a state in which the channel quality of the user equipment 120 is low, when the HARQ value indicating a plurality of feedback information in Table 1 is received, if the MCS index is increased as the base station 110 has received the ACK feedback, data reception The problem of increasing errors and high block error ratio (BLER) can occur.

In addition, in the case of receiving HARQ values indicating a plurality of feedback information in Table 1 in a state that the channel quality of the user equipment 120 is good, if the MCS index is reduced as if the base station 110 received the NACK feedback, the transmission rate This can lead to problems that decrease and degrade the performance of the data transmission system.

Meanwhile, when HARQ feedback and SR (Scheduling Request) are simultaneously transmitted, the user equipment 120 reports the number of ACKs as shown in Table 2 by using a special bundling mode.

For example, in the special bundling mode, when there are four downlink assignments and all four are ACKs or only one is ACK, the user equipment 120 reports 1 as the HARQ value to the base station 110.

In a state where the channel quality of the user equipment 120 is low, when the base station 110 receives 1 as the HARQ value for four downlink allocations, the base station 110 processes the number of ACKs as four to increase the MCS index. I can make it. In this case, data reception errors may further increase and block error rates may increase.

In addition, in a state in which the channel quality of the user equipment 120 is good, when the base station 110 receives 1 as the HARQ value for four downlink allocations, the base station 110 processes the number of ACKs as one, and the number of NACKs. The MCS index can be reduced by treating as three. In this case, a problem arises that the transmission rate decreases and the performance of the data transmission system is deteriorated.

Accordingly, in an LTE system in which HARQ feedback information indicates a plurality of HARQ values, a data transmission method for ensuring system performance and target block error ratio is required.

Hereinafter, a data transmission method will be described in detail with reference to FIGS. 3 and 4. The data transmission method described in FIGS. 3 and 4 may be performed by the processor 220 of the data transmission device 200.

3 is a flowchart of a data transmission method according to an embodiment.

The base station 110 transmits the downlink allocation of the user equipment 120, and receives HARQ feedback for the downlink allocation after the HARQ RTT.

The base station 110 determines whether HARQ feedback has been received (S301).

When HARQ feedback for downlink allocation of the user equipment 120 is received in the n-th subframe, the base station 110 determines the number of blocks of the user equipment 120 of the n-th subframe in each serving cell of the user equipment 120 Set (S302), and set the number of ACKs and the number of NACKs of the user equipment 120, respectively (S303).

The base station 110 determines the number of transmission blocks of the user equipment 120 in the n-th subframe of each serving cell of the user equipment 120 in the n-th subframe (downlink allocation transmission time + HARQ_RTT) at the time of receiving HARQ feedback. It can be set to the number of downlink allocations for each serving cell.

When receiving the ACK as the HARQ value for each downlink allocation, the base station 110 increases the number of ACKs of the corresponding serving cell by 1, and when receiving NACK, DTX, or NACK_OR_DTX as the HARQ value, the number of NACKs of the corresponding serving cell is 1 Increase.

And when the base station 110 receives the HARQ value for downlink allocation in the n-th subframe as one of ACK_OR_NACK, ACK_OR_DTX, ACK_OR_NACK_OR_DTX, the number of NACKs for downlink allocation of each serving cell is 1×block error ratio (n-1 ), and the number of ACKs increases with a 1-block error rate (n-1). The block error ratio (n-1) refers to the block error ratio during the measurement interval of the latest block error ratio from the n-1 th subframe.

When receiving HARQ feedback indicating a plurality of HARQ values such as ACK_OR_NACK, ACK_OR_DTX, ACK_OR_NACK_OR_DTX, the base station 110 increases the number of NACKs and ACKs by reflecting the recent block error rate of the user equipment 120, so that the base station 110 is When the channel quality of 120) is low, the number of NACK increases is adjusted high, and when the channel quality of the user equipment 120 is good, the number of ACK increases is adjusted.

The base station 110 updates the block error rate of each user equipment 120 during the last block error rate measurement period from the n-th subframe of each serving cell (S304).

Here, the block error ratio measurement interval is predefined in units of subframes, and the block error ratio (n) of the user equipment 120 during the measurement interval of the latest block error ratio from the n-th subframe of each serving cell is the following equation: It is calculated according to 1.

Here, n is the block error rate, number of erroneous blocks is the number of error blocks in the block error rate measurement section, and the total number of blocks sent is the number of transport blocks in the block error rate measurement section.

In Equation 1, the number of transport blocks in the block error ratio measurement section is the total number of transport blocks of the user equipment 120 during the latest block error ratio measurement section from the n-th subframe of each serving cell, and the block error ratio measurement section The number of error blocks refers to the total number of NACKs of the user equipment 120 during the last block error ratio measurement period from the n-th subframe of each serving cell.

The base station 110 adjusts the MCS index of the user equipment 120 using the number of ACKs and the number of NACKs of the n-th subframe in each serving cell of the user equipment 120 (S305). For example, the base station 110 increases the MCS index by the number of ACKs × MCS_UP_SIZE by using the number of ACKs of the n-th subframe at the time point of the n-th subframe, and NACKs the MCS index by using the number of NACKs of the n-th subframe. It can be reduced by the number x MCS_DOWN_SIZE.

In addition, the block error ratio (n) during the measurement period from the n-th subframe measured by the base station 110 to the latest block error ratio may be used for MCS adjustment of the user equipment 120. For example, when the latest block error rate is higher than the reference value at the n-th subframe time point, the base station 110 may reduce the MCS index, and when the latest block error rate is lower than the reference value, the base station 110 ) Can increase the MCS index.

Meanwhile, when there is no HARQ feedback to be received from the user equipment 120 in the n-th subframe of the serving cell, the base station 110 determines the number of blocks of the user equipment 120 in the n-th subframe of the serving cell, When the number of ACKs and the number of NACKs are all set to 0, or when the base station 110 does not receive HARQ feedback for downlink allocation of the user equipment 120 in the n-th subframe, the base station 110 is in the corresponding serving cell. The number of ACKs of the user equipment 120 of the n-th subframe is set to 0, and the number of NACKs is set to the number of downlink allocations transmitted to the serving cell (S306).

Next, a method of setting the number of ACKs and the number of NACKs of a serving cell will be described in detail with reference to FIG. 4.

4 is a flowchart of a method of setting the number of ACKs and the number of NACKs of a serving cell according to an embodiment.

When receiving HARQ feedback for downlink allocation of the user equipment 120 in the n-th subframe in a special bundling mode, the base station 110 transmits the UE of the n-th subframe in each serving cell of the user equipment 120 The number of blocks is set as the number of downlink allocations of each serving cell (S302).

In addition, the base station 110 receives the HARQ value (value 0) received in the special bundling mode (see Table 2) and the number of ACKs and NACKs of the n-th subframe in each serving cell according to the number of downlink allocated transmissions of each serving cell. Is set (S303).

The base station 110 determines whether the number of ACKs has one value (S401). The base station 110 determines whether the number of ACKs has one value by using the total number of downlink allocations transmitted to all serving cells corresponding to HARQ feedback in the n-th subframe and the HARQ value (value 0).

(1) When the HARQ value (value 0) is 0 or 4 (DTX), the base station 110 sets the number of ACKs in the n-th subframe of each serving cell (S402) and sets the number of NACKs as follows (S403) )do.

Number of ACKs in each serving cell = 0

Number of NACKs of each serving cell = Number of downlink allocated transmissions of each serving cell

(2) When the total number of downlink allocations transmitted to all serving cells corresponding to HARQ feedback in the nth subframe is less than 4, the base station 110 transmits downlinks to all serving cells corresponding to HARQ feedback in the nth subframe. When the total number of link allocations is 4 and the HARQ value (value 0) is 2 or 3, and the total number of downlink allocations transmitted to all serving cells corresponding to HARQ feedback in the n-th subframe is 5 and the HARQ value (value 0) If is 3, the number of ACKs of the serving cell in the n-th subframe is set (S404) and the number of NACKs is set (S405) as follows.

Number of ACKs of each serving cell = HARQ value (value 0) × (number of downlink allocations of serving cells / total number of downlink allocations of all serving cells)

Number of NACKs of each serving cell = (Number of downlink allocated transmissions of each serving cell-Number of ACKs of each serving cell)

(3) In cases other than (1) and (2), the base station 110 determines that the total number of ACKs in all serving cells does not have one value, and the first serving cell in the n-th subframe as follows. The number of ACKs is set (S406), the number of ACKs is set (S407), and the number of NACKs is set (S408).

1st ACK number of each serving cell = HARQ value (value 0) × (number of downlink allocations of serving cell / total number of downlink allocations of all serving cells)

Number of NACKs of each serving cell = (number of downlink allocated transmissions of each serving cell-number of first ACKs of each serving cell) × block error ratio of serving cell (n-1)

Number of ACKs of each serving cell = Number of downlink allocated transmissions of each serving cell-Number of NACKs of each serving cell

In this way, when the total number of ACKs of all serving cells of the user equipment 120 does not have one value, that is, can have multiple values, the base station 110 determines the number of downlink allocations of each serving cell and the user By reflecting the recent block error rate of each serving cell of the equipment 120, increasing the number of NACKs of each serving cell or increasing the number of ACKs, the number of NACKs is further increased when the latest channel quality of the user equipment 120 is low. And, when the channel quality of the user equipment 120 is good recently, the number of ACKs may be further increased.

As described above, the data transmission method according to the embodiment adjusts the MCS index based on the number of ACKs and the number of NACKs measured by the base station 110, or BLER, so that the MCS index is adjusted in a state where the channel quality of the user equipment 120 is low. By reducing the block error rate, the problem of increasing the block error rate can be prevented, and when the channel quality of the user equipment 120 is good, the MCS index can be increased to increase system performance.

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 by those skilled in the art using the basic concept of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (4)

The base station, determining whether HARQ (Hybrid Automatic Retransmit request) feedback (feedback) from at least one user equipment has been received,
The base station, when the HARQ feedback is received, setting the number of transport blocks of user equipment corresponding to the HARQ feedback,
When the base station, when the value of the HARQ feedback indicates a plurality of HARQ values, the number of ACK (ACKnowledge) increases by a 1-block error rate, and the number of negative-ACKnowledge (NACK) increases by 1×block error rate, Setting the number of ACKs and the number of NACKs-The block error ratio is a ratio of the number of error blocks in the block error ratio measurement interval to the number of transport blocks in the block error ratio measurement interval-and
Updating, by the base station, the block error rate according to the number of ACKs and the number of NACKs
Data transmission method comprising a. The method of claim 1,
The base station adjusting the MCS index of the user equipment using the number of ACKs and the number of NACKs
Data transmission method further comprising a. The method of claim 1,
The step of setting the number of transport blocks of user equipment corresponding to the HARQ feedback,
When receiving the HARQ feedback in the special bundling mode in the n-th subframe, the base station is the number of downlink allocations for all serving cells of the user equipment, and the n-th subframe in each of all serving cells of the user equipment. Including the step of setting the number of transport blocks of the user equipment,
Data transfer method. The method of claim 3,
Setting the number of ACKs and the number of NACKs includes:
The total number of downlink allocations transmitted to all serving cells of the user equipment corresponding to the HARQ feedback in the n-th subframe and the total number of ACKs of all serving cells of the user equipment have one value using the HARQ feedback value. If it is determined that there is no, comprising the step of setting the number of ACKs and the number of NACKs of the user equipment,
Data transfer method.

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