KR20180033395A - Methods of data retransmission on the multiple numerology of 5G mobile communication - Google Patents

Abstract

The present invention proposes an HARQ operation method in a 3GPP NR system. However, an NR system itself is an embodiment, and the method of the present invention can be applied to all systems that operate channel coding and HARQ. A data retransmission method according to the present invention includes a step of comparing the length of a downlink block with the length of an uplink block in order to support optimal HARQ operation in a system having two or more unit block lengths, and a step of classifying an HARQ operating mode according to a comparison result.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for retransmitting data in a multi-

The present invention proposes a HARQ operation method in a 3GPP NR system. However, the NR system itself is an embodiment, and the method of the present invention can be applied to all systems that operate channel coding and HARQ.

The present invention relates to a data retransmission method, comprising: comparing a length of a downlink block with a length of an uplink block in order to support optimal HARQ operation in a system having two or more unit block lengths; A method and apparatus are provided that include a step of distinguishing an operating mode.

FIG. 1 is a diagram for explaining resource equalization when the length of a downlink block is shorter than the length of an uplink block. FIG.
2 is a diagram for explaining a case where the length of the downlink block is shorter than the length of the uplink block-bundling process.
3 is a diagram for explaining a case where the length of the downlink block is shorter than the length of the uplink block.
4 is a diagram for explaining a case where the length of the downlink block is longer than the length of the uplink block.
5 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.
6 is a diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Herein, the MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. In this specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) and coverage enhancement. Alternatively, the MTC terminal may refer to a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, the MTC terminal in this specification may mean a newly defined 3GPP Release-13 low cost (or low complexity) UE category / type for performing LTE-based MTC-related operations. Alternatively, the MTC terminal may support enhanced coverage over the existing LTE coverage or a UE category / type defined in the existing 3GPP Release-12 or lower that supports low power consumption, or a newly defined Release-13 low cost low complexity UE category / type.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data and the like. A wireless communication system includes a user equipment (UE) and a base station (BS, or eNB). The user terminal in this specification is a comprehensive concept of a terminal in wireless communication. It is a comprehensive concept which means a mobile station (MS), a user terminal (UT), an SS (User Equipment) (Subscriber Station), a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal and includes a Node-B, an evolved Node-B (eNB), a sector, a Site, a BTS A base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell.

That is, the base station or the cell in this specification is interpreted as a comprehensive meaning indicating a partial region or function covered by BSC (Base Station Controller) in CDMA, NodeB in WCDMA, eNB in LTE or sector (site) And covers various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, and small cell communication range.

Since the various cells listed above exist in the base station controlling each cell, the base station can be interpreted into two meanings. i) the device itself providing a megacell, macrocell, microcell, picocell, femtocell, small cell in relation to the wireless region, or ii) indicating the wireless region itself. i indicate to the base station all devices that are controlled by the same entity or that interact to configure the wireless region as a collaboration. An eNB, an RRH, an antenna, an RU, an LPN, a point, a transmission / reception point, a transmission point, a reception point, and the like are exemplary embodiments of a base station according to a configuration method of a radio area. ii) may indicate to the base station the wireless region itself that is to receive or transmit signals from the perspective of the user terminal or from a neighboring base station.

Therefore, a base station is collectively referred to as a base station, collectively referred to as a megacell, macrocell, microcell, picocell, femtocell, small cell, RRH, antenna, RU, low power node do.

Herein, the user terminal and the base station are used in a broad sense as the two transmitting and receiving subjects used to implement the technical or technical idea described in this specification, and are not limited by a specific term or word. The user terminal and the base station are used in a broad sense as two (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by a specific term or word. Here, an uplink (UL, or uplink) means a method of transmitting / receiving data to / from a base station by a user terminal, and a downlink (DL or downlink) .

There are no restrictions on multiple access schemes applied to wireless communication systems. Various multiple access schemes such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM- Can be used. An embodiment of the present invention can be applied to asynchronous wireless communication that evolves into LTE and LTE-advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB. The present invention should not be construed as limited to or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

In systems such as LTE and LTE-advanced, a standard is constructed by configuring uplink and downlink based on a single carrier or carrier pair. The uplink and the downlink are divided into a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel, a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control Channel (EPDCCH) Transmits control information through the same control channel, and is configured with data channels such as PDSCH (Physical Downlink Shared CHannel) and PUSCH (Physical Uplink Shared CHannel), and transmits data.

On the other hand, control information can also be transmitted using EPDCCH (enhanced PDCCH or extended PDCCH).

In this specification, a cell refers to a component carrier having a coverage of a signal transmitted from a transmission point or a transmission point or transmission / reception point of a signal transmitted from a transmission / reception point, and a transmission / reception point itself .

The wireless communication system to which the embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-point transmission / reception system in which two or more transmission / reception points cooperatively transmit signals. antenna transmission system, or a cooperative multi-cell communication system. A CoMP system may include at least two multipoint transmit and receive points and terminals.

The multi-point transmission / reception point includes a base station or a macro cell (hereinafter referred to as 'eNB'), and at least one mobile station having a high transmission power or a low transmission power in a macro cell area, Lt; / RTI >

Hereinafter, a downlink refers to a communication or communication path from a multipoint transmission / reception point to a terminal, and an uplink refers to a communication or communication path from a terminal to a multiple transmission / reception point. In the downlink, a transmitter may be a part of a multipoint transmission / reception point, and a receiver may be a part of a terminal. In the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted / received through a channel such as PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH is expressed as 'PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH are transmitted and received'.

In the following description, an indication that a PDCCH is transmitted or received or a signal is transmitted or received via a PDCCH may be used to mean transmitting or receiving an EPDCCH or transmitting or receiving a signal through an EPDCCH.

That is, the physical downlink control channel described below may mean a PDCCH, an EPDCCH, or a PDCCH and an EPDCCH.

Also, for convenience of description, EPDCCH, which is an embodiment of the present invention, may be applied to the portion described with PDCCH, and EPDCCH may be applied to the portion described with EPDCCH according to an embodiment of the present invention.

Meanwhile, the High Layer Signaling described below includes RRC signaling for transmitting RRC information including RRC parameters.

The eNB performs downlink transmission to the UEs. The eNB includes a physical downlink shared channel (PDSCH) as a main physical channel for unicast transmission, downlink control information such as scheduling required for reception of PDSCH, and uplink data channel A physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission in a Physical Uplink Shared Channel (PUSCH). Hereinafter, the transmission / reception of a signal through each channel will be described in a form in which the corresponding channel is transmitted / received.

In 3GPP LTE / LTE-A and many communication systems, CRC is inserted in the information to be transmitted, and it is confirmed whether the receiver has transmitted error-free, CRC check is performed, and HARQ acknowledgment is returned to the transmitter according to success, do. At this time, the timing of sending a message is strictly defined, and therefore, in the transmitting terminal, it is possible to know at a receiving timing only which information corresponds to the HARQ acknowledgment transmitted from the receiving terminal. In this case, it is important to grasp the channel characteristics mutually, because it determines the reception timing. Depending on the distance between the transmitter and the receiver, the transmission time can reach several milliseconds. This is because the round-trip time (RTT) can be changed according to the situation. In the case of NR, which has been discussed in RAN1 84bis conference, it is widely used in general broadband wireless communication environment eMBB, massive machine-type communication mMTC (ultra-low latency) and Low-Latency Communications), and assumes several numerology-based environments to accommodate different scenarios, channels, and frequency environments. In these various scenarios and environments, HARQ operation also changes, and various potential operating methods are actively discussed.

The information to be retransmitted is largely divided into a CC (Chase Combination) method and an IR (Incremental Redundancy) method. CC has the advantages of simple implementation and high IR performance. Which information to send is determined by prior consultation, but the implementation of transmission and reception timing is defined differently according to transmission characteristics and channel.

The conventional LTE / LTE-A HARQ has a timing based on a one-to-one correspondence between transmission blocks in each transmission and reception. That is, a block for HARQ acknowledgment corresponding to one block transmitted from the transmitter is included in the return message at the receiver. This one-to-one correspondence was possible because the unit of time for each block was equal to 1ms. However, transmission and reception blocks defined in NR may have various lengths depending on their numerology, which may result in inconsistency in the length of frames between transmission and reception ends. For example, in an environment where heterogeneous frequency CA is applied, it can be predicted that it will not be possible to construct an uplink numerology corresponding to all applied numerology, which is also true in a scenario where numerology is arranged differently for each frequency band. In particular, the channel state characteristics according to the respective numerology and reference frequency are quite different, and it is expected that the preferred numerology of the base station and the terminal is different in certain situations. If the lengths of the transmission and reception end frames do not coincide with each other, a one-to-one correspondence relationship to the transmission and reception blocks can not be maintained.

The present invention proposes a method for supporting optimum HARQ operation in a system having two or more unit block lengths. Through the proposed method, the receiver can send each HARQ acknowledgment corresponding to the transmission block regardless of the block unit.

The present invention largely consists of solutions to the two scenarios.

(1) HARQ acknowledgment processing method when the length of the downlink block is shorter than the length of the uplink block

(2) HARQ acknowledgment processing method when the length of the downlink block is longer than the length of the uplink block

In the operation description below, the data sending side is referred to as downlink, The side to which HARQ acknowledgment is sent is described as an uplink. However, the name does not limit the scope of the present invention, and in fact, the transmitting side may be the uplink and the downlink may be the one sending the HARQ acknowledgment. The method is also applicable to all communication systems capable of sending acknowledgments for transmission as well as HARQ.

(1) HARQ acknowledgement processing method of the downlink if the length of the block is less than the uplink block length if applicable, there is generated this is transmitted and received only do not have a one-to-one correspondence between the block conflicts, three ways for handling it The method can be thought of.

① way to enable more acknowledgement HARQ process of varying the size of transmission: As shown in Figure 2, to send more than one HARQ acknowledgement in a block, a method of further securing the message transfer position. At this time, in order to facilitate the delay processing, it is advantageous to arrange each transmission equally in time in the block. This is the most intuitive method, but there is a drawback that transmission capacity is somewhat reduced. There are two methods in detail here.

i) Method of operating the ACK / NACK bit as many as the number of blocks to be operated: The method is the same as the ACK / NACK in which the bits of the information constituting the HARQ acknowledgment are to be sent. This is an existing processing method. It is effective to arrange the HARQ acknowledgment transmission resources so that the ACK / NACK of each block can be interpreted by the transmitter at the same interval as the block ratio. For example, if the block length difference is k times, the message space for HARQ acknowledgment at 1 / k intervals as shown in Fig. 2 can minimize the delay caused by the processing time.

ii) Method of coding ACK / NACK bit stream: The method is a method of reducing the average message by performing coding depending on the probability based on the bit stream in i). For example, when the rate of occurrence of NACK relative to ACK is significantly low, the average bit length can be greatly reduced by using Huffman coding or similar Huffman coding. For example, the following operating methods are possible.

Example 1: When sending two bits

0: when both are ACK

100: When only the first NACK

110: When NACK is the second time

11: When both are NACK

Embodiment 2: When sending four bits

0: When net is ACK

10xx: When only one bit is NACK, the position of NACK bit is specified by xx

110xxx: When two bits are NACK, the position of ACK bit is specified as xxx

1110xx: When three bits are NACK, specify the position of ACK bit with xx

1111: When all bits are NACK

You can map this way. It is assumed that the number of bits when all bits are NACK is rather low because most NACK occurs when the channel condition deteriorates momentarily and the frequency is higher than when NACK is used for three bits.

The purpose of the coding applied to the A / N bitstream may be to reduce the average message length as described in the previous embodiments, but to increase the reliability of the bitstream. For example, in order to transmit multiple information, the modulation order may be increased. In this case, since the reliability of individual bits is lowered, the corresponding method may be used to secure the reliability of bits by performing appropriate channel coding.

(2) Method of transmitting multiple information at the same time by using upper modulation : This method is a method of raising the modulation order of the transmission block to send at least twice HARQ acknowledgment in one block. For example, BPSK can be operated with QPSK and QPSK with 16QAM when double operation is required. The need for additional channels is eliminated, but the reliability of HARQ acknowledgments or control messages including them is reduced.

Methods (1) -① and (1) -② may be operated at the same time. For example, it is possible to increase the modulation order and apply channel coding with a low coding rate to maintain bit reliability.

(3) A method in which one HARQ acknowledgment corresponds to two or more downlink transmission blocks : The method comprehensively determines two or more pieces of information received in a unit time corresponding to the length of an uplink block, The NACK is transmitted as shown in Fig. This scheme is simple but does not change the structure of the frame, but the information received successfully is also retransmitted, which reduces the overall transmission amount.

④ Method of operating (1) -① and (1) -② or (1) -③ at the same time: The method is a method of (1) -① and (1) (2), or (1) - (3) at the same time. For example, as shown in Fig. 4, when the difference between the lengths of the uplink block and the downlink block is large, the overhead may increase greatly in the method (1) - (3). Therefore, ) -①, (1) -②, or a combination of both.

In the case of mixed coding schemes, the following special methods may exist.

First, if there is no NACK to send, 00 is sent.

If the NACK is 1, it sends 01.

If there are two NACKs, one in the front two and one in the back two, send 10.

In the other case, 11 is sent.

In each case, the retransmission value is determined as follows.

It is not sent when 00 comes.

When 01 comes, it sends a + b + c + d.

When 10 comes, it sends a + b, c + d.

When 11 comes, it sends a, b, c, d.

This method has a disadvantage in that a bit overflow and an additional operation are required and a large overhead occurs when the retransmitted bit fails again. Also, the approach to the same idea for more than five bits makes the coding become dramatically complicated.

However, this method can reduce the number of excess retransmission blocks on the average compared with the method described in Fig. For example, compare this method to the method in Figure 4

The number of retransmission blocks is reduced by one for the case where one block fails to decode.

The average number of retransmission blocks is reduced by 2/3 when two blocks fail to decode.

The reason is that, in the case of the method, the number of retransmission blocks is 2 for four of six patterns in which two blocks fail to decode, and the number of retransmission blocks is 4 for the remaining two, resulting in an average of 8/3. In the case of Fig. 4, the number of retransmission blocks is 2 for 2 patterns among the 6 patterns and the number of retransmission blocks is 4 for the remaining 4 patterns.

Since the remaining cases are the same, but they do not increase, the total number of retransmission blocks is reduced.

(2) HARQ acknowledgement processing method of the downlink if the length of the block is longer than the uplink block length: if applicable, sending a HARQ acknowledgement messages for downlink transmission block, as shown in Figure 1 position to bring a constant time delay It is uniquely determined. In this case, it is sufficient to send the HARQ acknowledgment in the same manner as the conventional method. Only a few blocks that do not necessarily send an HARQ response inevitably occur. The processing for such a case may be as follows.

(1) Method of sending equal HARQ acknowledgment in all corresponding uplink transmission blocks : This method is a method of transmitting an equal HARQ acknowledgment message in all adjacent uplink transmission blocks which can correspond to one transmission downlink block. For example, if the block length is 4 times as shown in Fig. 1, an ACK or NACK message is transmitted in the same four blocks in the uplink. The advantage of diversity gain can be obtained in the transmitter without changing the structure of the frame have. Equivalence here is all changeable sets that can be recognized as ACK at the receiving end. For example, if ACK and NACK are sent, ACK, and if NACK and ACK are sent, NACK can be recognized beforehand.

② method of the corresponding all uplink transmission block to the receiving terminal sends a random or predetermined HARQ acknowledgement part only: the method is a method to send a HARQ acknowledgement in some blocks of the available block, adding to that the frame structure not include HARQ acknowledgement Although it is necessary to define it, there is an advantage that additional transmission capacity can be secured. If the transmission position of the HARQ acknowledgment is defined in advance, it is easy to confirm at the transmitting end. If the transmitting position is arbitrary, the transmitting end needs to perform blind decoding, thereby reducing the reliability but adding more flexibility to the position selection at the receiving end . The number of blocks sending an HARQ acknowledgment may be increased to compensate for reduced reliability.

(3) Method of transmitting HARQ acknowledgment in some uplink transmission block and transmitting additional information in remaining block : This method is a method in which additional information that is not necessarily required to be transmitted or received, Link transmission block in the HARQ acknowledgment transmission channel. (1) -① can also be seen as a subset of this method. More specific information may include an update to the CQI information by informing that the decoding succeeded but the probability of a noise ratio failure is high, and may also request an elasticity of the IR / CC or control the length of the IR.

The present invention proposes a HARQ operation method for systems with different unit block lengths between uplink and downlink that can be supported by the next generation communication system NR. An efficient HARQ system can be operated in the corresponding system through the method described in the present invention.

5 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.

5, a base station 1000 according to another embodiment includes a control unit 1010, a transmission unit 1020, and a reception unit 1030.

The controller 1010 controls the overall operation of the base station according to support of optimal HARQ operation in a system having two or more unit block lengths necessary for performing the present invention.

The transmitting unit 1020 and the receiving unit 1030 are used to transmit and receive signals, messages, and data necessary for carrying out the present invention to and from the terminal.

6 is a diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

6, a user terminal 1100 according to another embodiment includes a receiving unit 1110, a control unit 1120, and a transmitting unit 1130.

The receiving unit 1110 receives downlink control information, data, and messages from the base station through the corresponding channel.

In addition, the controller 1120 controls the overall operation of the UE supporting optimal HARQ operation in a system having two or more unit block lengths necessary for performing the present invention.

The transmitter 1130 transmits uplink control information, data, and a message to the base station through the corresponding channel.

The standard content or standard documents referred to in the above-mentioned embodiments constitute a part of this specification, for the sake of simplicity of description of the specification. Therefore, it is to be understood that the content of the above standard content and some of the standard documents is added to or contained in the scope of the present invention, as falling within the scope of the present invention.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (1)

In a data retransmission method,
Comparing a length of a downlink block with a length of an uplink block to support optimal HARQ operation in a system having two or more unit block lengths; And
And classifying the HARQ operation mode according to the comparison result.

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