KR20180033393A - Methods of data retransmission for 5G mobile communication - Google Patents

Abstract

The present invention proposes an HARQ operation method in a 3GPP NR system. However, the NR system itself is an embodiment, and the method proposed in the present invention can be applied to all systems that operate channel coding and HARQ. The present invention provides a method and apparatus for retransmitting data. The method for retransmitting data includes the steps of: receiving implicit information for a block indicated by one HARQ acknowledgment; and performing a data retransmission operation based on the implicit information. Accordingly, the present invention can provide temporal flexibility.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for retransmitting data for 5G mobile communication,

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 provides a data retransmission method, comprising: receiving implicit information for a block indicated by one HARQ acknowledgment; and performing a data retransmission operation based on the implicit information.

Fig. 1 is a diagram for explaining an operation in the second embodiment. Fig.
2 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.
3 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 information to be transmitted, and it is checked whether the receiver has transmitted error-free. CRC check is performed to return HARQ ACK / NACK message to the transmitter Perform the request. At this time, the timing of sending the message is strictly defined, and therefore, the transmitting terminal can know at a receiving timing only which information corresponds to the ACK / NACK message transmitted from the receiving end. 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.

In the conventional HARQ, in order to clarify the message for certain information, the HARQ message to be sent must exist in one block, that is, one information processing unit. That is, the block pointed to by the HARQ acknowledgment object is clearly defined, and therefore, there must be an individual HARQ acknowledgment for every block. Generally, HARQ acknowledgment information consists of one bit but it requires many resources such as repetition in order to transmit it with a low error rate. In a situation where several blocks are processed at the same time, a lot of overhead may be required for transmission of HARQ acknowledgment it means.

The present invention proposes an implicit transmission method for a block indicated by one HARQ acknowledgment. Through the proposed method, the number of bits required for HARQ acknowledgment transmission can be greatly reduced, but time flexibility can be expected without additional signaling. In the former case, the UE can simultaneously perform HARQ acknowledgment processing for two or more blocks. In the latter case, the UE can send an ACK / NACK message by selecting any of two or more possible times. This is possible because the base station can successfully transmit necessary additional information even though the base station can not determine which information is HARQ. The present invention is applicable to all retransmission techniques such as HARQ as well as ARQ.

The present invention is roughly divided into two.

(1) A method of sending an ACK message by implicitly making HARQ block information on the UE side

(2) a method of responding to a NACK message received from the base station without information of the correct block

Herein, the UE and the BS are used to distinguish between a side that sends a HARQ ACK and a side that processes a response to the HARQ ACK. In actuality, the UE and the BS may be rearranged, or both the UE and the BS may use the same method Can be applied. Although the present invention assumes and describes the HARQ system for the sake of convenience, the present invention can be applied to all communication systems capable of feedback of success / failure to the transmitted values.

Description of the Invention

(1) Method of sending an ACK message by implicitly transmitting HARQ block information on the terminal side: At the terminal side, only the ACK / NACK message for a specific part of several blocks is transmitted to the base station. This information is expressed in a more approximate manner than the precise position information to be originally transmitted. For example, only k of n blocks are transmitted in the form of ACK / NACK.

As one embodiment, if four blocks are processed at the same time, all the terminals are successful in decoding / one decoding failed / two failed / three or four failed, The HARQ acknowledgment can be transmitted in only two bits.

As another embodiment, it is assumed that an original information block is received and an ACK / NACK message can be sent at n different timings. And the time values at this time are s [1], s [2], ... , s [n]. Where s [1] <s [2] <... < s [n].

The UE sends an ACK / NACK message for the information block A received at the reception time T at a time of T + s [k] for a properly selected k. Here, the conventional method needs to send information about k separately, but the proposed method does not send information about k.

(2) A method of responding to the NACK message received from the base station without correct block information: If the ACK is received at the base station side, there is no additional work to be performed. However, if NACK is received, the following procedure is performed.

First, the base station determines what it should send based on information that the sender knows but does not send. In other words, the sender transmits information in a form that can extract necessary information based on the additional information sent from the sender. For example, in the case of the first embodiment,

For example, if all the information received by the base station is decoded successfully, the base station need not send additional information.

If the information received by the base station is a decoding failure of a block, the base station generates additional information for all the blocks in a predetermined manner, integrates the block into an operation capable of inverse operation, and sends the information to the information amount of one block. A terminal that knows a, b, and c knows xabc = d through x and the information it knows, if x = a + b + c + d. A terminal that knows a, b, and d can get xabd = c through x and the information it knows. That is, the information transmitted by the base station is x. This type of typical operation is XOR, but any operation that can satisfy one-to-one correspondence is possible.

However, in the case of this embodiment, the number of retransmission blocks is increased because the number of blocks required for the retransmission block can not be transmitted for the following cases. However, if 3 bits are used instead of 2 bits, it is easy to obtain a solution in which the number of retransmission blocks and the number of necessary blocks are equal to each other.

In the terminal

If there is no NACK to send, 000 is sent.

If there is one NACK to send, it sends 001.

If there is one failure in a, b, and there is one failure in c, d, send 010.

If both a and b fail, or c and d both fail, send 011.

If a NACK is 3 and a or b succeeds, it sends 100.

If the NACK is 3 and c or d succeeds, then 101 is sent.

If there are 4 NACKs, 110 is sent.

In response to this,

I do not send it when 000 comes.

When 001 arrives, it sends a + b + c + d

When 010 arrives, it sends a + b, c + d.

When 011 arrives, it sends a + c, b + d.

If 100 comes, send a + b, c, d.

If 101 comes, send a, b, c + d.

When 110 comes, send a, b, c, d.

For the second embodiment:

First, the base station transmits a signal to the terminal by s [1], s [2], ... , s [n] can not be known. However, it is possible to prepare n candidate information blocks to be sent on the assumption that each is selected. For example, A [1] is the information block to be actually requested when the time of s [1] is selected, and A [2] is the time when s [2] is selected. Assuming that the transmission / reception transmission delay is d, A [k] is a signal transmitted from the base station by 2d + s [k] before now. Since s [k] is a positive number, the base station can always obtain all information from A [1] to A [n].

The base station then performs the operations of Equation 1 or Equation 2.

R = XOR (CC (A [1]), CC (A [2]),  (One)

R = XOR (IR (A [1]), IR (A [2]),  (2)

Here, XOR (A, ...) denotes a result obtained by XORing an information block of all input values bit by bit. CC (A) is information to be sent by the base station when NACK is received for A in the Chase Combine scenario, and IR (A) is information to be sent by the base station when NACK is received for A in the incremental redundancy scenario. The resulting R is sent to the HARQ retransmission at a time off the processing time c at the receiving time.

The UE can receive the retransmission information R transmitted from the base station after the time 2d + c, and performs calculation of Equation 3 or 4 on the basis of the information k of the UE, [k]) / IR (A [k]).

CC (A [k]) = XOR (CC (A [1]), CC (A [ ..., CC (A [n])) ... (3)

IR (A [k]) = XOR (A [1]), IR (A [ ..., IR (A [n])) ... (4)

Of course, this operation can only be done after all A [] except A [k] have been successfully received. If more than one of them is in the process of retransmission, the recovery of necessary information will be delayed as much. If there is no retransmission process, A [1] to be received at the terminal after the last will be received after s [k] -s [1] at A [k] = A, S [k] is unconditionally transferred. Therefore, at the receiving time, all information is received after successful reception.

For the sake of comprehension, s [2] is selected when n = 3, d = 2, c = 1, s [1] = 3, s [2] = 5, s [3] = 6. 1.

(3) Exception processing method: In Embodiment 2, there are some problems different from Embodiment 1. There are cases where two or more symbols collide with each other depending on the situation. In case of ACK, it does not matter but in case of NACK, the following solution is performed.

The block that has selected the longest delay among the collided blocks performs NACK transmission at the corresponding position and the remainder changes the retransmission position to the nearest one of the delay slots after it is possible. This operation is repeated until the slot is lost. Since there is always one block without a delay slot, it is always possible to allocate, so that a retransmission request can always be performed without a block that prevents a request for retransmission.

The problem is that if there is a collision, one or more unknowns will occur when calculating equations 3 and 4. In this case, it is necessary to wait until the unknown number is decoded by retransmission, which results in a reduction in delay. Alternatively, the soft value received at that time may be used to perform the XOR operation without waiting for the retransmission. In this case, there is a disadvantage that the noise power is multiplied by x according to the unknown number x including R. Of course, how to deal with it is an implementation issue. However, if some conditions are met, there may be a special solution:

If n = 2 and s [2] -s [1] = d: At this time, special handling may be required for case where NACK comes twice with d intervals.

First, if the first NACK is selected by selecting s [1], it can be seen that the second NACK is also selected by selecting s [1]. Because if you choose s [2], the signal will be sent two NACKs. - Case 1.

Also, if the first NACK is selected by selecting s [2], the second NACK is the signal that is separated by d by selecting s [2]

It can be seen that the signal separated by 2d is selected by selecting s [1]. - Case 3.

Therefore, two NACKs arriving at intervals of d are NACK requests for two blocks transmitted at intervals of d or 2d. In this case, place the previous block in order of time in r, q, q, and d. Also, the block previously received by p before d is set to p, and the block to be received later by d after r is set to s. And finally, we assume that p is received correctly, that is, it is known at the request of the retransmission request.

In Case 1, p + q is sent in response to the first NACK. And in response to the second NACK, q + r will come in. Since p is already known, q and r can be recovered in order at the receiving end.

In case 3, q + r is transmitted in response to the first NACK. And in response to the second NACK, r + s will come in. Here, the receiving end can successfully recover q and s by using r received successfully. Here, r was successfully received because case 2 would have occurred.

In Case 2, however, q + r is sent in response to the first NACK and r + s is received in response to the second NACK. With these two retransmission values, q can not be known until s is received, and if s retransmission fails, decoding continues to be delayed. Therefore, in this case, it is preferable to send r, not r + s.

However, in this case, r / s can not be recovered in case 1/3. Because in the case 1/3, the sender will send q / r. Therefore, the transmitting end selects s [1] to send a NACK for q, and if it fails to decode r after q after d time , s (s) By selecting [2] to send a NACK for q, and then failing to decode the ons after 2d hours in q, force a NACK on r / s to select s [2] I will not . When the NACK is received twice at the interval of d in the receiving end, the second NACK always retransmits only the earliest block among the added blocks.

In this case, in the case of the NACK coming in at the interval of 2d, the receiver can recognize that the second choice is s [2]. Since this is the information to be recovered, it is necessary to retransmit only the earliest block in this case, and to prevent the block from being selected from this slot. That is, if an error occurs at 2d intervals, s [2] should be selected for the second error.

On the other hand, these ideas can be extended even beyond n = 3. In this case, it is necessary to force all the intervals to be the same and always select the highest delay value for any collision. For example, if n = 3 and s [2] = s [1] + d, s [3] = s [2] + d, the block received at d intervals or the block received at 2d intervals consecutively fails decoding , All blocks are forced to select s [3] so that NACK is not sent at intervals d. And restricts the delay selection in subsequent errors so that in this case s [3] can be selected so that this fact can be passed, the slot to be sent is not selected. At the receiving end, all NACKs arriving at d intervals are sent to the most advanced block. The method is defined as follows.

In an environment defined by a constant s [k + 1] -s [k] = d, the receiver can use rd for any decimal integer r that is not decodable, If both of the blocks of the interval fail to decode, the temporal backward block selects a delay maximum value s [n] and sends a NACK. Also, if a block with an interval of (n + k) for k smaller than n fails to decode, it selects only after s [n-k] and sends a NACK.

In the transmitting end, if the interval between two NACKs is rd, the response to the second NACK is sent in the order of the block to be XORed, in the order of the most preceding block.

The implicit HARQ operation proposed in the present invention has the following advantages.

(1) The amount of information for signaling necessary for the HARQ retransmission process can be reduced.

(2) Multi-mode support with multiple delays is possible.

However, in the present invention, an extra buffer and calculation process are required for calculation such as XOR in the transmission / reception end.

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

2, 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 the implicit transmission method for the block indicated by one HARQ acknowledgment, which is necessary for performing the above-described 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.

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

3, a user terminal 1100 according to another embodiment of the present invention 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.

Also, the controller 1120 controls the overall operation of the UE according to the implicit transmission method for the block indicated by one HARQ acknowledgment, which is necessary for performing the above-described 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,
Receiving implicit information for a block indicated by one HARQ acknowledgment; And
And performing a data retransmission operation based on the implicit information.

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