WO2016078328A1

WO2016078328A1 - Automatic retransmission method and apparatus

Info

Publication number: WO2016078328A1
Application number: PCT/CN2015/077419
Authority: WO
Inventors: 许辉; 刘卓
Original assignee: 中兴通讯股份有限公司
Priority date: 2014-11-21
Filing date: 2015-04-24
Publication date: 2016-05-26
Also published as: CN105681001B; CN105681001A

Abstract

An automatic retransmission method and apparatus. The method comprises: sending, by a Medium Access Control (MAC) layer of an evolved Node B (eNodeB), Hybrid Automatic Retransmission Quest (HARQ) new transmission to a MAC layer of a User Equipment (UE); and when the MAC layer of the eNodeB does not receive an Acknowledgement response (ACK) and a Negative Acknowledgement response (NACK) of the MAC layer of the UE, not performing, by the MAC layer of the eNodeB, HARQ retransmission, and informing an RLC layer of Automatic Retransmission Quest (ARQ) retransmission.

Description

Method and device for automatic retransmission

Technical field

This document relates to automatic retransmission techniques, and more particularly to an automatic retransmission method and apparatus.

Background technique

FIG. 1 is a schematic diagram of an air interface protocol stack of a Long Term Evolution (LTE) network. Referring to Figure 1, the LTE network guarantees the transmission reliability of the air interface from two aspects. One is the automatic retransmission request (ARQ, Automatic Repeat) of the radio link control (RLC) layer acknowledgement mode (AM, Acknowledged Mode). The second is the hybrid automatic repeat request (HARQ, Hybrid ARQ) of the Medium Access Control (MAC) layer.

The HARQ transmission is divided into a new transmission and a retransmission. If the HARQ retransmission exceeds the maximum number of times, the HARQ retransmission fails. The RLC layer of the user equipment (UE, User Equipment) notifies the evolved Node B (eNodeB, Evolved Node B, through the status report). The RLC layer of the LTE base station, and then the RLC layer of the eNodeB retransmits the corresponding message. Since ARQ retransmission is higher than the protocol level involved in HARQ retransmission, the delay is even larger. In order to reduce the retransmission delay, after the HARQ retransmission fails, the MAC layer of the eNodeB can directly notify the RLC layer to perform ARQ retransmission without waiting for the status report of the UE RLC layer.

The unit of HARQ transmission is TB, and one TB is a data block containing a MAC message. The TB size is specified by the MCS index. The MCS index has 5 bits, but only 29 combinations (0 to 28) are used, and the remaining 3 combinations (29 to 31) are reserved, and the three combinations are Only for retransmission. The size of the transport block (TB) is generally specified in the newly transmitted downlink control information (DCI, Downlink Control Information) by the Modulation and Coding Scheme (MCS) index, and the TB size during the HARQ retransmission. It does not change, so the retransmitted DCI does not re-instruct the size of the TB. If the UE does not successfully receive the newly transmitted DCI, the UE fails to demodulate the UE after receiving the HARQ retransmitted message because the TB is not known. After the UE demodulation fails, a non-acknowledgement (NACK, Negative Acknowledgement) is sent to the eNodeB, thereby triggering the ARQ. Therefore, the delay of the RLC layer retransmission is long.

Summary of the invention

This paper proposes a method and apparatus for automatic retransmission, which can reduce the retransmission delay.

An automatic retransmission method includes:

The medium access control MAC layer of the evolved Node B eNodeB sends a hybrid automatic repeat request HARQ new transmission to the MAC layer of the user equipment UE;

When the MAC layer of the eNodeB does not receive the acknowledgment response ACK and the non-acknowledgement response NACK of the MAC layer of the UE, the MAC layer of the eNodeB does not perform HARQ retransmission, and notifies the RLC layer to perform automatic retransmission request ARQ retransmission.

Optionally, when the MAC layer of the eNodeB receives the non-acknowledgment response NACK of the MAC layer of the UE, the method further includes:

The MAC layer of the eNodeB performs HARQ retransmission.

An automatic retransmission device includes:

The MAC layer sending module is configured to: send a hybrid automatic repeat request HARQ new transmission to the MAC layer of the user equipment UE;

The notification module is configured to: when the MAC layer does not receive the ACK and NACK of the MAC layer of the UE, perform no HARQ retransmission, and notify the RLC layer to perform automatic retransmission request ARQ retransmission;

The RLC layer sending module is configured to: perform an RLC layer automatic retransmission request ARQ retransmission according to the notification of the notification module.

Optionally, the MAC layer sending module is further configured to:

When the MAC layer receives the non-acknowledgment response NACK of the MAC layer of the UE, the MAC layer performs HARQ retransmission.

A computer readable storage medium storing computer executable instructions for performing the methods described above.

Compared with the related art, the embodiment of the present invention includes: the MAC layer of the eNodeB sends a new HARQ transmission to the MAC layer of the UE; when the MAC layer of the eNodeB does not receive the ACK and the NACK of the MAC layer of the UE, the MAC layer of the eNodeB does not perform HARQ retransmits and notifies the RLC layer ARQ retransmission. With the solution of the embodiment of the present invention, when the MAC of the eNodeB does not receive the ACK or NACK of the MAC layer of the UE, the RLC layer is immediately notified to perform ARQ retransmission without continuing to perform HARQ retransmission, thereby reducing retransmission. The delay and the elimination of meaningless HARQ retransmissions save valuable air interface resources.

BRIEF abstract

The drawings in the embodiments of the present invention will be described below.

1 is a schematic diagram of an air interface protocol stack of an LTE network of the related art;

2 is a flowchart of a method for automatic retransmission according to an embodiment of the present invention;

3 is a flowchart of an embodiment of a method for automatic retransmission according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of an apparatus for automatic retransmission according to an embodiment of the present invention.

Embodiments of the invention

Embodiments of the present invention will be described below with reference to the accompanying drawings. It should be noted that the embodiments in the embodiments and the various manners in the embodiments may be combined with each other without conflict.

HARQ retransmission does not carry TB size information and must rely on new transmission. If the UE fails to correctly demodulate the DCI when the HARQ is newly transmitted, the UE does not know the TB size regardless of how many times the HARQ retransmission is performed, so the HARQ retransmission in this case certainly fails, which is meaningless.

The embodiment of the present invention optimizes the situation. When the MAC layer of the eNodeB does not receive the ACK (Acknowledgement) or NACK (Negative Acknowledgement) of the HARQ, the UE fails to demodulate the DCI, and stops the HARQ process. The RLC layer immediately begins ARQ retransmission.

Referring to FIG. 2, an embodiment of the present invention provides a method for automatic retransmission, including:

Step 200: The MAC layer of the eNodeB sends a HARQ new transmission to the MAC layer of the UE.

In this step, the HARQ new transmission includes DCI and corresponding data.

The MAC layer of the UE first detects the DCI, and acquires data according to the detected DCI. When the MAC layer of the UE successfully obtains data, the ACK is sent to the eNodeB; when the MAC layer of the UE does not successfully obtain the data, the NACK is sent to the eNodeB.

When the MAC layer of the UE does not detect DCI, the MAC layer of the UE does not send ACK and NACK to the eNodeB.

Step 201: When the MAC layer of the eNodeB does not receive the acknowledgment response (ACK, Acknowledgement) and NACK of the MAC layer of the UE, the MAC layer of the eNodeB does not perform HARQ retransmission, and immediately sends a message to notify the RLC layer to perform ARQ retransmission.

When the eNodeB transmits data in a subframe, it receives feedback (ACK or NACK) of the UE in the Mth subframe thereafter, where M is a preset positive integer. For example, in a Frequency Division Duplex (FDD) system, feedback is received after 4 subframes. In this step, when the MAC layer of the eNodeB does not receive the ACK or NACK of the MAC layer of the UE, indicating that the UE fails to demodulate the DCI, the current HARQ process is stopped, and the RLC layer is notified to immediately start the ARQ retransmission.

In this step, when the MAC layer of the eNodeB receives the NACK of the MAC layer of the UE, the MAC layer of the eNodeB performs HARQ retransmission.

The method of the embodiment of the present invention will be described in detail below by way of examples.

As shown in FIG. 3, the method includes:

Step 300: The eNodeB RLC layer sends an RLC Protocol Data Unit (PDU) to the MAC layer.

In this step, the RLC PDU is an ARQ new transmission or an ARQ retransmission.

Step 301: The MAC layer of the eNodeB sends a MAC PDU to the UE MAC layer.

In this step, the MAC PDU is a new transmission of HARQ.

Step 302: If the eNodeB MAC layer does not receive the ACK and NACK of the MAC layer of the UE, the MAC layer of the eNodeB does not perform HARQ retransmission, and immediately notifies the RLC layer of the eNodeB to retransmit the corresponding RLC PDU.

In this step, if the eNodeB MAC layer receives the NACK of the MAC layer of the UE, the MAC layer of the eNodeB performs HARQ retransmission.

As shown in FIG. 4, an apparatus for automatic retransmission according to an embodiment of the present invention includes:

The MAC layer sending module 41 is configured to: send a HARQ new transmission to the MAC layer of the UE;

The notification module 42 is configured to: when the MAC layer does not receive the ACK and the NACK of the MAC layer of the UE, perform no HARQ retransmission, and notify the RLC layer to perform ARQ retransmission;

The RLC layer sending module 43 is configured to: perform an RLC layer automatic retransmission request ARQ retransmission according to the notification of the notification module.

In the apparatus of the embodiment of the present invention, the MAC layer sending module 41 is further configured to:

When the MAC layer receives the NACK of the MAC layer of the UE, the MAC layer performs HARQ retransmission.

One of ordinary skill in the art will appreciate that all or a portion of the steps of the above-described embodiments can be implemented using a computer program flow, which can be stored in a computer readable storage medium, such as on a corresponding hardware platform (eg, The system, device, device, device, etc. are executed, and when executed, include one or a combination of the steps of the method embodiments.

Alternatively, all or part of the steps of the above embodiments may also be implemented by using an integrated circuit. These steps may be separately fabricated into individual integrated circuit modules, or multiple modules or steps may be fabricated into a single integrated circuit module. achieve.

The devices/function modules/functional units in the above embodiments may be implemented by a general-purpose computing device, which may be centralized on a single computing device or distributed over a network of multiple computing devices.

When the device/function module/functional unit in the above embodiment is implemented in the form of a software function module and sold or used as a stand-alone product, it can be stored in a computer readable storage medium. The above mentioned computer readable storage medium may be a read only memory, a magnetic disk or an optical disk or the like.

Industrial applicability

In the embodiment of the present invention, when the MAC of the eNodeB does not receive the ACK or the NACK of the MAC layer of the UE, the RLC layer is immediately notified to perform the ARQ retransmission, and the HARQ retransmission is not required, thereby reducing the delay of the retransmission. It also saves meaningless HARQ retransmissions, saving valuable air interface resources.

Claims

An automatic retransmission method includes:

The medium access control MAC layer of the evolved Node B eNodeB sends a hybrid automatic repeat request HARQ new transmission to the MAC layer of the user equipment UE;

When the MAC layer of the eNodeB does not receive the acknowledgment response ACK and the non-acknowledgement response NACK of the MAC layer of the UE, the MAC layer of the eNodeB does not perform HARQ retransmission, and notifies the RLC layer to perform automatic retransmission request ARQ retransmission.
The method according to claim 1, when the MAC layer of the eNodeB receives the non-acknowledgment response NACK of the MAC layer of the UE, the method further includes:

The MAC layer of the eNodeB performs HARQ retransmission.
An automatic retransmission device includes:

The MAC layer sending module is configured to: send a hybrid automatic repeat request HARQ new transmission to the MAC layer of the user equipment UE;

The notification module is configured to: when the MAC layer does not receive the ACK and NACK of the MAC layer of the UE, perform no HARQ retransmission, and notify the RLC layer to perform automatic retransmission request ARQ retransmission;

The RLC layer sending module is configured to: perform an RLC layer automatic retransmission request ARQ retransmission according to the notification of the notification module.
The apparatus according to claim 3, wherein the MAC layer sending module is further configured to:

When the MAC layer receives the non-acknowledgment response NACK of the MAC layer of the UE, the MAC layer performs HARQ retransmission.
A computer readable storage medium storing computer executable instructions for performing the method of claim 1 or 2.