CN109560896B

CN109560896B - Method and system for data transmission based on code block group in 5G system

Info

Publication number: CN109560896B
Application number: CN201710872362.3A
Authority: CN
Inventors: 焦慧颖
Original assignee: China Academy of Information and Communications Technology CAICT
Current assignee: China Academy of Information and Communications Technology CAICT
Priority date: 2017-09-25
Filing date: 2017-09-25
Publication date: 2021-10-08
Anticipated expiration: 2037-09-25
Also published as: CN109560896A

Abstract

The application provides a method and a system for data transmission based on code block groups in a 5G system, wherein the method comprises the following steps: the base station configures the number N of CBGs corresponding to a transport block TB and sends the number N to the terminal to enable the terminal to acquire the number of CBGs corresponding to the TB; the base station divides the TB to be transmitted into N CBGs and sends the TB to the terminal by taking the CBG as a unit; when a terminal receives a TB with CBG as a unit, receiving N CBGs for the TB, and respectively carrying out HARQ feedback according to the condition of receiving each CBG; and the base station receives HARQ feedbacks of the terminal aiming at all CBGs, retransmits the CBG of which the corresponding feedback content is NACK when detecting and determining that the content with the HARQ feedback is NACK, and informs the terminal of the retransmitted CBG through downlink control information. The scheme can improve the utilization rate of system resources.

Description

Method and system for data transmission based on code block group in 5G system

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method and a system for data transmission based on code block groups in a 5G system.

Background

LTE supports Transport Block (TB) based transmission, i.e. one TB in a Transport channel corresponds to one codeword of the physical layer, which is physically performing channel coding and other related operations.

Considering the performance of channel coding and the factors of processing delay, if the length of a Code word data stream after adding CRC bits is greater than 6144, the Code words need to be separated, one Code word is separated into a plurality of Code Blocks (CBs), corresponding CRC bits are added to each Code Block, and then channel coding is performed by taking the Code Block as a unit, so as to meet the limitation of the maximum length of channel coding, but data scheduling, retransmission and the like are still based on a transmission Block, that is, even if only one CB fails to decode, retransmission of the whole TB is caused.

In consideration of the diversity of the 5G service, the amount of service data can be large or small. If the transmission is carried out in the 5G system by using the TB-based mode, the utilization rate of system resources is greatly reduced.

Disclosure of Invention

In view of this, the present application provides a method and a system for data transmission based on code block groups in a 5G system, which can improve the utilization rate of system resources.

In order to solve the technical problem, the technical scheme of the application is realized as follows:

a method for data transmission based on code block groups in a 5G system, the method comprising:

the base station configures the number N of CBGs corresponding to a transport block TB and sends the number N to the terminal to enable the terminal to acquire the number of CBGs corresponding to the TB; wherein N is an integer greater than 0;

the base station divides the TB to be transmitted into N CBGs and sends the TB to the terminal by taking the CBG as a unit;

when a terminal receives a TB with CBG as a unit, receiving N CBGs for the TB, and respectively carrying out HARQ feedback according to the condition of receiving each CBG;

and the base station receives HARQ feedbacks of the terminal aiming at all CBGs, retransmits the CBG of which the corresponding feedback content is NACK when detecting and determining that the content with the HARQ feedback is NACK, and informs the terminal of the retransmitted CBG through downlink control information.

A system for data transmission based on code block groups in a 5G system, the system comprising: a base station and a terminal;

the base station configures the number N of CBGs corresponding to a transport block TB and sends the number N to the terminal to enable the terminal to acquire the number of CBGs corresponding to the TB; dividing a TB to be transmitted into N CBGs, and sending the TB to a terminal by taking the CBG as a unit; when HARQ feedbacks of the terminal aiming at all CBGs are received and the content with the HARQ feedbacks is detected and determined to be NACK, the CBG with the corresponding feedback content as NACK is retransmitted and the terminal is informed of the retransmitted CBG through downlink control information; wherein N is an integer greater than 0;

when the terminal receives the TBs with the CBG as the unit, all the CBGs are received according to the number of the CBGs corresponding to the TB, and HARQ feedback is respectively carried out according to the condition of receiving each CBG.

According to the technical scheme, the TB is divided into the CBGs with the number corresponding to the configured number of the CBGs, the TB is transmitted by taking the CBG as a unit, and when the CBG which fails to transmit exists in the transmission, only the CBG which fails to transmit is retransmitted, but the whole TB is not retransmitted. The scheme can improve the utilization rate of system resources.

Drawings

Fig. 1 is a schematic flowchart illustrating data transmission based on code block groups according to a first embodiment of the present application;

fig. 2 is a diagram of retransmission according to the first embodiment;

fig. 3 is a schematic flowchart illustrating data transmission based on code block groups according to a second embodiment of the present application;

fig. 4 is a retransmission diagram according to the second embodiment.

Fig. 5 is a schematic flowchart of data transmission based on code block groups according to a third embodiment of the present application;

fig. 6 is a diagram of retransmission according to the third embodiment;

fig. 7 is a schematic flowchart illustrating data transmission based on code block groups according to a fourth embodiment of the present application;

fig. 8 is a diagram of retransmission according to the fourth embodiment;

fig. 9 is a schematic diagram of a system applied to the above technology in the embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly apparent, the technical solutions of the present invention are described in detail below with reference to the accompanying drawings and examples.

In the embodiment of the present application, a method for data transmission based on Code Block groups in a 5G system is provided, where a TB is divided into CBGs with a number corresponding to the number of configured Code Block Groups (CBGs), and the TB is transmitted by using the CBGs as a unit, and when there is a failed CBG in transmission, only the failed CBG is retransmitted, instead of retransmitting the entire TB. The scheme can improve the utilization rate of system resources.

The following describes the procedures of the present application based on code block transmission in a 5G system in detail with reference to the embodiments.

It should be noted that, in this embodiment of the present application, the base station needs to pre-configure the number N of CBGs, and when it needs to send one TB, the TB is divided into N CBG groups according to the size of the TB in an equalization principle, in a specific implementation, the TB is divided into multiple CBs, and then the multiple CBs are divided into N CBG groups according to the equalization principle, if the current TB is divided into M CBs, the M/N CBs are divided into each CBG, and if M/N is not an integer, the remaining number of CBs are divided into different CBG groups according to a preset principle, such as a random principle, a sequential arrangement principle, and the like.

Wherein, N is an integer greater than 0, and for the big data packet service type, N is an integer greater than 1; for the small data packet service type, N is 1.

When the uplink coverage is poor and multiple carriers, N may also be configured as 1, that is, the backoff is substantially based on data transmission in TB unit, and hereinafter, referred to as data transmission in TB unit.

In particular implementations, the number of CBGs may be configured in an RRC semi-static manner, such that it is not necessary to dynamically change the size of the number of CBGs sent each time.

The base station sends the configured number N of CBGs to the terminal, so that the terminal knows the number of CBGs corresponding to the TB, and when receiving the TB, the number of CBGs to be received for the TB can be determined.

The base station may indicate the number of code blocks corresponding to the initial transmission transport block through higher layer RRC signaling.

In a specific implementation, a field may be used to indicate which way to use to transmit the TB, such as a named transport way field, where 0 is used to indicate transmission in CBG unit, and 1 is used to indicate transmission in TB unit, that is, a CBG group is divided.

Example one

Referring to fig. 1, fig. 1 is a schematic flowchart illustrating data transmission based on code block groups according to a first embodiment of the present application. The method comprises the following specific steps:

step 101, the base station divides the TB to be transmitted into N CBGs and sends the TB to the terminal in units of CBGs.

Step 102, when the terminal receives a TB with CBG as a unit, the terminal receives N CBGs for the TB, and performs Hybrid Automatic Repeat ReQuest (HARQ) feedback according to the condition of receiving each CBG.

103, the base station receives HARQ feedback of the terminal for all CBGs, and retransmits the CBG of which the corresponding feedback content is NACK when detecting and determining that the content of the HARQ feedback is NACK, and notifies the terminal of the retransmitted CBG through downlink control information.

When the base station notifies the terminal of the retransmitted CBG through the downlink control information, whether each CBG is transmitted or not may be indicated in a 0/1bitmap manner, and if the CBG is transmitted, it is indicated by 1, and if the CBG is not transmitted, it is indicated by 0.

The following example is provided to illustrate the specific implementation of the present embodiment:

referring to fig. 2, fig. 2 is a schematic diagram of retransmission according to the first embodiment. Assuming that the number of CBGs configured by the RRC is 3, that is, N is 3, when initially transmitting, the downlink control information bitmap is 111, which indicates that all three CBGs are transmitted.

In fig. 2, the HARQ content fed back to CBG3 is NACK. Therefore, the CBG3 is retransmitted, and at this time, the downlink control information bitmap is 001, which indicates that the third CBG is transmitted.

Example two

Referring to fig. 3, fig. 3 is a schematic flow chart of data transmission based on code block groups according to a second embodiment of the present application. The method comprises the following specific steps:

step 301, the base station divides the TB to be transmitted into N CBGs and sends the TB to the terminal in units of CBGs.

Step 302, when the terminal receives a TB with CBG as a unit, the terminal receives N CBGs for the TB, and performs HARQ feedback according to the condition of receiving each CBG.

Step 303, the base station receives HARQ feedback of the terminal for all CBGs, and retransmits the CBG of which the corresponding feedback content is NACK when detecting that the content of the HARQ feedback is NACK, and notifies the terminal of the retransmitted CBG through downlink control information.

And step 304, when the terminal determines that the current CBG is the retransmission CBG, performing HARQ feedback for the CBG according to the current situation of receiving the CBG.

The embodiment of the application provides a HARQ feedback mode aiming at the retransmitted CBG. Referring to fig. 4, fig. 4 is a schematic diagram of retransmission according to the second embodiment. HARQ feedback is only done for the retransmitted CBG3 in this embodiment.

EXAMPLE III

Referring to fig. 5, fig. 5 is a schematic flow chart of data transmission based on code block groups according to a third embodiment of the present application. The method comprises the following specific steps:

step 501, the base station divides the TB to be transmitted into N CBGs and sends the TB to the terminal in units of CBGs.

Step 502, when the terminal receives a TB with CBG as a unit, the terminal receives N CBGs for the TB, and performs HARQ feedback according to the condition of receiving each CBG.

Step 503, the base station receives HARQ feedback of the terminal for all CBGs, and retransmits the CBG of which the corresponding feedback content is NACK when detecting and determining that the content of the HARQ feedback is NACK, and notifies the terminal of the retransmitted CBG through downlink control information.

In step 504, when determining that the current CBG is the retransmission CBG, the terminal performs HARQ feedback for all CBGs corresponding to the TB corresponding to the retransmission CBG.

The embodiment of the application provides a HARQ feedback mode aiming at the retransmitted CBG. Referring to fig. 6, fig. 6 is a schematic diagram of retransmission according to a third embodiment.

The number of CBGs configured by RRC in fig. 6 is 3, and the base station detects NACK error of CBG3 fed back by the terminal as NACK, and the UE feeds back HARQ status of all CBGs (including NACK of CBG 3) again to improve reliability. I.e. only CBG3 is retransmitted, HARQ feedback will be done for CBG1, CBG2, CBG 3.

When the base station erroneously receives the uplink HARQ feedback sent by the terminal, there are two situations, one is that the base station side erroneously decodes ACK fed back by the terminal HARQ-ACK into NACK, at this time, the base station retransmits the corresponding CBG, and notifies the terminal through the downlink control information DCI that the CBG is retransmitted, and correct decoding of the terminal is not affected. However, when the base station side decodes NACK fed back by the terminal HARQ-ACK erroneously into ACK, the base station will not retransmit the CBG until the RLC layer retransmits the entire transport block, and the retransmission delay is considered, so that the embodiment of the present application performs HARQ retransmission on all CBGs to solve the problem that the base station erroneously decodes uplink HARQ, which can improve the reliability of uplink HARQ.

Example four

In this embodiment, implementation of HARQ feedback based on a TB is added on the basis of the second embodiment and the third embodiment.

In the following, the implementation of adding HARQ feedback based on TB to the third embodiment is taken as an example. Referring to fig. 7, fig. 7 is a schematic flowchart of data transmission based on code block groups according to a fourth embodiment of the present application. The method comprises the following specific steps:

in step 701, the base station divides the TBs to be transmitted into N CBGs and sends the TBs to the terminal in units of CBGs.

Step 702, when the terminal receives a TB with CBGs as a unit, the terminal receives N CBGs for the TB, and performs HARQ feedback according to the condition of receiving each CBG; and performs HARQ feedback based on the TB.

In step 703, the base station receives HARQ feedback of the terminal for all CBGs, and retransmits the CBG whose feedback content is NACK when detecting that it is determined that the content of the HARQ feedback is NACK, and notifies the terminal of the retransmitted CBG through downlink control information.

Step 704, when determining that the current CBG is the retransmission CBG, the terminal performs HARQ feedback for all CBGs corresponding to the TB corresponding to the retransmission CBG, and performs HARQ feedback based on the TB.

When the terminal performs HARQ feedback based on the TB, when the received TB composed of all CBGs is correctly received, determining that the content corresponding to the HARQ feedback based on the TB is ACK; otherwise, determining that the content corresponding to the HARQ feedback based on the TB is NACK.

Step 705, when determining that the received content corresponding to the HARQ feedback based on the CBG is ACK and the received content corresponding to the HARQ feedback based on the TB is NACK, the base station retransmits the TB to the terminal in the CBG unit according to the configured number of CBGs.

After this step, the terminal performs the content of step 702, i.e. whether the entire TB is retransmitted or transmitted for the first time, feedback is made for all CBGs.

And ending the transmission of the TB until the base station determines that the received contents corresponding to the HARQ feedback based on the CBG are all ACK and the received contents corresponding to the HARQ feedback based on the TB are ACK.

In the embodiment of the application, the terminal feeds back the HARQ feedback based on the transport block by adding 1 or 2 bits while sending the HARQ feedback based on the actually sent CBG, and the scheme can further solve the problem that the base station wrongly decodes the uplink HARQ and improve the reliability of the base station correctly decoding the HARQ feedback.

Referring to fig. 8, fig. 8 is a schematic diagram of retransmission according to a fourth embodiment. Fig. 8 shows that the number of CBGs configured by RRC is 3, the base station detects a NACK error of CBG3 fed back by the terminal as ACK, but the terminal feeds back NACK based on TB (consisting of 3 CBGs), so the base station can determine that a detection error of the base station and the terminal for uplink feedback or a detection error of HARQ feedback for TB is certain, and at this time, the entire transport block needs to be retransmitted, that is, the transmission mode based on the transport block is returned; without having to wait for RLC retransmissions.

In specific implementation, different PDCCH format indications are used for TB-based data transmission (initial transmission or retransmission) and CBG-based data transmission (initial transmission or retransmission).

Aiming at the condition that initial transmission and retransmission based on CBG have the same DCI, the same PDCCH format is used for indicating, information bits of the initial transmission and the retransmission are multiplexed, and the initial transmission and the retransmission are distinguished through 1bit, for example, 0 is used for indicating the initial transmission, and 1 is used for indicating the retransmission; conversely, the same may be true.

Since some bits, such as TB indicator, need only be present at the initial transmission and some bits, such as bitmap information sent by each CBG, need only be present at the retransmission, these bits may have different roles at the initial transmission and the retransmission. During specific implementation, the method can be specifically designed according to actual needs, and the field multiplexing or adding is not limited during specific implementation of the method, so long as specific functions are realized.

In the embodiments one to four of the present application, data transmission is performed in units of CBGs, and data transmission in units of TBs may refer to the existing implementation, for example, it is not necessary to indicate which CBG retransmission is required.

Based on the same inventive concept, the application also provides a system for data transmission based on the code block group in the 5G system. Referring to fig. 9, fig. 9 is a schematic diagram of a system applied to the above technology in the embodiment of the present application. The system comprises: a base station 901 and a terminal 902;

the base station 901 configures the number N of CBGs corresponding to the transport block TB, and sends the number N to the terminal 902, so that the terminal 902 knows the number of CBGs corresponding to the TB; dividing the TB to be transmitted into N CBGs, and transmitting the TB to the terminal 902 in units of CBGs; when receiving HARQ feedback of the terminal 902 for all CBGs and detecting that it is determined that the content with HARQ feedback is NACK, retransmitting the CBG whose corresponding feedback content is NACK, and notifying the terminal 902 of the retransmitted CBG through downlink control information; wherein N is an integer greater than 0;

when receiving a TB with CBG as a unit, terminal 902 receives all CBGs for the number of CBGs corresponding to the TB, and performs HARQ feedback according to the condition of receiving each CBG.

Preferably, the first and second liquid crystal films are made of a polymer,

when determining that the current CBG is the retransmission CBG, the terminal 902 performs HARQ feedback for all CBGs corresponding to TBs corresponding to the retransmission CBG.

Preferably, the first and second liquid crystal films are made of a polymer,

the terminal 902 performs HARQ feedback based on the TB, wherein when the received TB composed of all CBGs is correctly received, it is determined that the content corresponding to the HARQ feedback based on the TB is an acknowledgement ACK; otherwise, determining that the content corresponding to HARQ feedback based on the TB is NACK;

when receiving that all the contents corresponding to the HARQ feedback performed based on the CBG are ACK and that the content corresponding to the HARQ feedback performed based on the TB is NACK, the base station 901 retransmits the TB to the terminal 902 in units of CBG according to the number of configured CBGs.

In summary, according to the present application, the TBs are divided into CBGs with the number corresponding to the configured CBG number, and the TBs are transmitted by using the CBGs as a unit, and when there is a CBG that fails in transmission, only the failed CBG is retransmitted, instead of retransmitting the entire TB. The scheme can improve the utilization rate of system resources.

In the specific implementation of the method, a base station indicates the number of code blocks corresponding to an initial transmission transport block through high-level RRC signaling, a new DCI format is designed to indicate which downlink CBGs are transmitted during initial transmission and retransmission, a terminal feeds back HARQ-ACK of the whole transport block by adding 1 or 2 bits on the basis of feeding back HARQ-ACK of each scheduled CBGs, and therefore the problem that the base station possibly decodes the HARQ-ACK incorrectly is solved.

In the 5G system, based on a code block separated scheduling mode and a corresponding HARQ feedback mode, a method for indicating the number of code block groups by a base station, a method for indicating which code block groups are sent during initial transmission/retransmission by the base station and a method for feeding back HARQ-ACK feedback based on the code block groups by a terminal are provided to solve the problem of HARQ decoding errors of the base station.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method for data transmission based on code block groups in a 5G system, the method comprising:

the base station configures the number N of Code Block Groups (CBGs) corresponding to a Transport Block (TB) and sends the number N to the terminal to enable the terminal to acquire the number of the CBGs corresponding to the TB; wherein N is an integer greater than 0;

when a terminal receives a TB with CBG as a unit, receiving N CBGs for the TB, and respectively carrying out hybrid automatic repeat request (HARQ) feedback according to the condition of receiving each CBG;

the base station receives HARQ feedbacks of the terminal aiming at all CBGs, retransmits the CBG of which the corresponding feedback content is NACK when detecting and determining that the content with the HARQ feedbacks is negative ACK NACK, and informs the terminal of the retransmitted CBG through downlink control information;

wherein the method further comprises:

when the terminal determines that the current CBG is the retransmission CBG, HARQ feedback is carried out on all CBGs corresponding to the TB corresponding to the retransmission CBG;

the data transmission based on the CBG and the data transmission based on the TB use different physical downlink control channel PDCCH format indications;

aiming at the condition that the initial transmission and the retransmission based on the CBG have the same downlink control information DCI, the same PDCCH format indication is used, the information bits of the initial transmission and the retransmission are multiplexed, and the initial transmission and the retransmission are distinguished through 1 bit.

2. The method of claim 1, further comprising:

the terminal carries out HARQ feedback based on the TB, wherein when the received TB composed of all CBGs is correctly received, the content corresponding to the HARQ feedback based on the TB is determined to be ACK confirmation; otherwise, determining that the content corresponding to HARQ feedback based on the TB is NACK;

and when the base station receives that the contents corresponding to the HARQ feedback based on the CBG are all ACK and the contents corresponding to the HARQ feedback based on the TB are NACK, retransmitting the TB to the terminal by taking the CBG as a unit according to the number of the configured CBG.

3. The method according to claim 1 or 2,

when the number of CBGs corresponding to the TB is configured, the configuration is carried out in a RRC semi-static mode.

4. The method of claim 3, wherein the partitioning the TB into corresponding CBGs in accordance with the number of configured CBGs comprises:

and dividing the TB into CBG groups corresponding to the number of the configured CBGs according to the size of the TB and the balance principle.

5. The method according to claim 1 or 2,

for a big data packet service type, N is an integer greater than 1; for the small data packet service type, N is 1.

6. A system for data transmission based on code block groups in a 5G system, the system comprising: a base station and a terminal;

the base station configures the number N of Code Block Groups (CBGs) corresponding to a Transport Block (TB) and sends the number N to the terminal to enable the terminal to acquire the number of the CBGs corresponding to the TB; dividing a TB to be transmitted into N CBGs, and sending the TB to a terminal by taking the CBG as a unit; when hybrid automatic repeat request (HARQ) feedback of a terminal for all CBGs is received and the content with the HARQ feedback is determined to be Negative Acknowledgement (NACK), retransmitting the CBG with the corresponding feedback content being NACK, and informing the terminal of the retransmitted CBG through downlink control information; wherein N is an integer greater than 0;

when the terminal receives the TBs with the CBGs as the unit, receiving all the CBGs aiming at the number of the CBGs corresponding to the TB, and respectively carrying out HARQ feedback according to the condition of receiving each CBG;

7. The system of claim 6,