WO2021062707A1

WO2021062707A1 - Communication methods, devices and computer readable media therefor

Info

Publication number: WO2021062707A1
Application number: PCT/CN2019/109606
Authority: WO
Inventors: Lin Liang; Gang Wang
Original assignee: Nec Corporation
Priority date: 2019-09-30
Filing date: 2019-09-30
Publication date: 2021-04-08

Abstract

Embodiments of the present disclosure relate to communication methods, devices and computer readable medium therefor. In an embodiment of the present disclosure, a communication method is performed at a terminal device. In the method, the terminal device receives a feedback indication for a last transmitted for Hybrid Automatic Repeat reQuest (HARQ) feedback of the terminal device from a network device, the feedback indication indicating whether the last transmitted HARQ feedback was receive. Based on the received feedback indication, the terminal device further determines a downlink assignment index (DAI) value, starting from which another HARQ feedback is to be generated, wherein the DAI value is a next DAI value of a DAI corresponding to a last received HARQ feedback of the network device. Then, the terminal device generates the other HARQ feedback starting from the determined DAI.

Description

COMMUNICATION METHODS, DEVICES AND COMPUTER READABLE MEDIA THEREFOR

FIELD OF THE INVENTION

The non-limiting and exemplary embodiments of the present disclosure generally relate to the field of wireless communication techniques, and more particularly relate to communication methods, devices and computer readable media in a wireless communication system.

BACKGROUND OF THE INVENTION

This section introduces aspects that may facilitate better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

New radio access system, also called as NR system or NR network, is the next generation communication system. The third generation Partnership Project (3GPP) working group was already approved the study of the NR system. The NR system will consider frequency ranging up to 100Ghz with an object of a single technical framework addressing all usage scenarios, requirements and deployment scenarios, which includes requirements such as enhanced mobile broadband, massive machine-type communications, and ultra-reliable and low latency communications.

In order to provide an improved data rate performance, in the 3GPP Long Term Evolution (LTE) , there was introduced unlicensed band operation for both downlink and uplink transmission, which is well known License Assisted Access (LAA) . As the Long Term Evolution (LTE) network enters its next phase of evolution with the study of wider bandwidth waveform under the NR project, solutions on the NR unlicensed band (NR-U) are studied.

Hybrid Automatic Repeat reQuest (HARQ) and HARQ-ACK feedback is one of key features in the NR system. In HARQ-ACK feedback design, the robustness issue shall be considered to reduce impacts of missed detection and missed transmission of feedback on the NR system. For NR operations on unlicensed band, as interference increases, the probability of missed detection and missed transmission of feedback (containing HARQ-ACK bits) due to an LBT failure would increase accordingly. Thus, it requires some enhancements on the NR system, especially enhancements on HARQ codebook in the NR-U system such as the way of using the Counter Downlink Assignment Index (C-DAI) , one-shot HARQ-ACK feedback, etc., are needed to redesigned.

SUMMARY OF THE INVENTION

In general, example embodiments of the present disclosure provide a new solution for simultaneous connection based handover in a wireless communication system.

According to a first aspect of the present disclosure, there is provided a communication method. The communication method may be implemented at a terminal device, and one of its objects is to provide an improved Hybrid Automatic Repeat reQuest (HARQ) feedback. The communication method may include receiving, from a network device, a feedback indication for a last transmitted HARQ feedback of the terminal device, the feedback indication indicating whether the last transmitted HARQ feedback was received; determining, based on the received feedback indication, a downlink assignment index (DAI) value starting from which another HARQ feedback is to be generated, wherein the DAI value is a next DAI value of a DAI corresponding to a last received HARQ feedback of the network device; and generating the other HARQ feedback starting from the determined DAI.

According to a second aspect of the present disclosure, there is provided a communication method. The communication method may be implemented at a terminal device, and one of its objects is to provide an improved Hybrid Automatic Repeat reQuest (HARQ) feedback. The communication method may include receiving a one-shot HARQ feedback trigger information from the network device and generating a one-shot HARQ feedback with a feedback value for a HARQ identity indicating an expected new data indication (NDI) value of the terminal device in accordance with determination that a one-short feedback transmission is trigged by the network device.

According to a third aspect of the present disclosure, there is provided a communication method. The communication method may be implemented at a network device, and one of its objects is to provide an improved Hybrid Automatic Repeat reQuest (HARQ) feedback. The communication method may include transmitting a feedback indication for a last transmitted HARQ feedback of a terminal device to the terminal device, the feedback indication indicating whether the last transmitted HARQ feedback was received; receiving another HARQ feedback from the terminal device; and determining a DAI value starting from which the other HARQ feedback was generated based on whether the last transmitted HARQ feedback was received, wherein the DAI value is a next DAI value of a DAI corresponding to a last received HARQ feedback of the network device.

According to a fourth aspect of the present disclosure, there is provided a communication method. The communication method may be implemented at a network device, and one of its objects is to provide an improved Hybrid Automatic Repeat reQuest (HARQ) feedback. The communication method may include transmitting a downlink control indication to the terminal device, to trigger a one-short feedback transmission; receiving a one-shot HARQ feedback from the terminal device, wherein the one-shot HARQ feedback has a feedback value for a HARQ identity indicating an expected NDI value of the terminal device; and performing the following data retransmission based on the expected NDI value and a current NDI value.

According to a fifth aspect of the present disclosure, there is provided a terminal device. The terminal device may include at least one processor and at least one memory coupled with the at least one processor. The terminal device has computer program codes stored therein which are configured to, when executed on the at least one processor, cause the terminal device to perform operations of any of the first aspect.

According to a sixth aspect of the present disclosure, there is provided a terminal device. The terminal device may include at least one processor and at least one memory coupled with the at least one processor. The terminal device has computer program codes stored therein which are configured to, when executed on the at least one processor, cause the terminal device to perform operations of any of the second aspect.

According to a seventh aspect of the present disclosure, there is provided a network device. The network device may include at least one processor and at least one memory coupled with the at least one processor. The network device has computer program codes stored therein which are configured to, when executed on the at least one processor, cause the network device to perform operations of any of the third aspect.

According to an eighth aspect of the present disclosure, there is provided a network device. The network device may include at least one processor and at least one memory coupled with the at least one processor. The network device has computer program codes stored therein which are configured to, when executed on the at least one processor, cause the network device to perform operations of any of the fourth aspect.

According to a ninth aspect of the present disclosure, there is provided a computer-readable storage medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to perform actions in the method according to any embodiment in any of the first aspect.

According to a tenth aspect of the present disclosure, there is provided a computer-readable storage medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to perform actions in the method according to any embodiment in any of the second aspect.

According to a eleventh aspect of the present disclosure, there is provided a computer-readable storage medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to perform actions in the method according to any embodiment in any of the third aspect.

According to a twelfth aspect of the present disclosure, there is provided a computer-readable storage medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to perform actions in the method according to any embodiment in any of the fourth aspect.

According to a thirteenth aspect of the present disclosure, there is provided a computer program product comprising a computer-readable storage medium according to the ninth aspect.

According to a fourteenth aspect of the present disclosure, there is provided a computer program product comprising a computer-readable storage medium according to the tenth aspect.

According to a fifteenth aspect of the present disclosure, there is provided a computer program product comprising a computer-readable storage medium according to the eleventh aspect.

According to a sixteenth aspect of the present disclosure, there is provided a computer program product comprising a computer-readable storage medium according to the twelfth aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and benefits of various embodiments of the present disclosure will become more fully apparent from the following detailed description with reference to the accompanying drawings, in which like reference signs are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and are not necessarily drawn to scale, in which:

Fig. 1 schematically illustrates an existing HARQ feedback solution;

Fig. 2 schematically illustrates a communication method at a terminal device according to embodiments of the present disclosure;

Fig. 3 illustrates an example solution of determining a DAI value from which another HARQ feedback is to be generated according to embodiments of the present disclosure;

Figs. 4A to 4C illustrate an example HARQ feedback solution according to embodiments of the present disclosure;

Figs. 5A to 5C illustrate alternative HARQ feedback solutions according to embodiments of the present disclosure;

Fig. 6 schematically illustrates a communication method at a network device according to embodiments of the present disclosure;

Fig. 7 illustrates an existing one-shot HARQ feedback according to embodiments of the present disclosure;

Fig. 8 illustrates a communication method at a terminal device according to embodiments of the present disclosure;

Figs. 9A to 9D illustrate example HARQ feedback solutions according to embodiments of the present disclosure;

Fig. 10 schematically illustrates a communication method at a network device according to embodiments of the present disclosure; and

FIG. 11 schematically illustrates a simplified block diagram of a communication system 1100 that can implement the communication solution according to embodiments of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, the solutions as provided in the present disclosure will be described in details through embodiments with reference to the accompanying drawings. It should be appreciated that these embodiments are presented only to enable those skilled in the art to better understand and implement the present disclosure, not intended to limit the scope of the present disclosure in any manner. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. In the interest of clarity, not all features of an actual implementation are described in this specification.

In the accompanying drawings, various embodiments of the present disclosure are illustrated in block diagrams, flow charts and other diagrams. Each block in the flowcharts or blocks may represent a module, a program, or a part of code, which contains one or more executable instructions for performing specified logic functions, and in the present disclosure, a dispensable block is illustrated in a dotted line. Besides, although these blocks are illustrated in particular sequences for performing the steps of the methods, as a matter of fact, they may not necessarily be performed strictly according to the illustrated sequence. For example, they might be performed in reverse sequence or simultaneously, which is dependent on natures of respective operations. It should also be noted that block diagrams and/or each block in the flowcharts and a combination of thereof may be implemented by a dedicated hardware-based system for performing specified functions/operations or by a combination of dedicated hardware and computer instructions.

References in the specification to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be liming of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

As used herein, the term “wireless communication network” refers to a network following any suitable wireless communication standards, such as New Radio (NR) , Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , and so on. The “wireless communication network” may also be referred to as a “wireless communication system. ” Furthermore, communications between network devices, between a network device and a terminal device, or between terminal devices in the wireless communication network may be performed according to any suitable communication protocol, including, but not limited to, Global System for Mobile Communications (GSM) , Universal Mobile Telecommunications System (UMTS) , Long Term Evolution (LTE) , New Radio (NR) , wireless local area network (WLAN) standards, such as the IEEE 802.11 standards, and/or any other appropriate wireless communication standard either currently known or to be developed in the future.

As used herein, the term “network device” refers to a node in a wireless communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a NR NB (also referred to as a gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology.

As used herein, the term “terminal device” refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE) , personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs) , portable computers, tablets, wearable devices, internet of things (IoT) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, device on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, or image capture devices such as digital cameras, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like.

In one embodiment, the terminal device may be connected with a first network device and a second network device. One of the first network device and the second network device may be a master node and the other one may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs) . In one embodiment, the first network device may be a first RAT device and the second network device may be a second RAT device. In one embodiment, the first RAT device is eNB and the second RAT device is gNB. Information related with different RATs may be transmitted to the terminal device from at least one of the first network device and the second network device. In one embodiment, a first information may be transmitted to the terminal device from the first network device and a second information may be transmitted to the terminal device from the second network device directly or via the first network device. In one embodiment, information related with configuration for the terminal device configured by the second network device may be transmitted from the second network device via the first network device. Information related with reconfiguration for the terminal device configured by the second network device may be transmitted to the terminal device from the second network device directly or via the first network device.

As a yet another example, in an Internet of Things (IOT) scenario, a terminal device may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another terminal device and/or network equipment. The terminal device may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as a machine-type communication (MTC) device. As one particular example, the terminal device may be a UE implementing the 3GPP narrow band internet of things (NB-IoT) standard. Examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances, for example refrigerators, televisions, personal wearables such as watches etc. In other scenarios, a terminal device may represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

As used herein, a downlink (DL) transmission refers to a transmission from a network device to UE, or from a network device as a parent node to another network device as a child node, and an uplink (UL) transmission refers to a transmission in an opposite direction.

As mentioned before, for NR operations on unlicensed band, as interference increases, the probability of missed detection and missed transmission of feedback (containing HARQ-ACK bits) due to Listen Before Talk (LBT) failure would increase accordingly. Thus, it requires some enhancements on dynamic HARQ codebook in the NR-U system, such as the way of using the DAI, the one-shot HARQ-ACK feedback, etc.

Embodiments of the present disclosure provide new communication solutions in a wireless communication system and one of the objects is to provide improved HARQ feedback. In some embodiments of the present disclosure, the network device transmits a feedback indication for the last transmitted feedback to the terminal device. Based on the feedback indication, the terminal device could determine the last feedback received by the network device and in turn determine the DAI value starting from which another HARQ feedback is to be generated as a next DAI value of a DAI corresponding to the last received feedback. In this way, a dynamic HARQ-ACK accumulated C-DAI could be generated, which could facilitate missed detection of downlink control information (DCI) transmission. In some other embodiments of the present disclosure, a one-shot HARQ feedback can be generated with a feedback value for a HARQ identity indicating an expected new data indication (NDI) value of the terminal device, upon a one-short feedback transmission is trigged by the network device. Thus, the one-shot HARQ feedback could provide more effective feedback information, which will improve the existing one-shot HARQ feedback greatly.

Hereinafter, reference will be further made to accompanying drawings to describe the solutions as proposed in the present disclosure in details. However, it shall be appreciated that the following embodiments are given only for illustrative purposes and the present disclosure is not limited thereto. In addition, the solution as provided herein can be used in the NR system, the NR-U system or any other communication with similar issues.

Reference will be first made to Fig. 1 to describe an existing HARQ feedback solution. In the legacy NR dynamic HARQ codebook, the C-DAI starts from 0 for one HARQ feedback occasion, for example one PUCCH occasion. As illustrated in Fig. 1, if the assignment information with DAI=2 is missed, a terminal device could know the missing from the inconsecutive DAI values and transmit HARQ feedback starting from 0 with an HARQ feedback value for DAI=2 as NACK. However, when the assignment information regarding DAI=3 is missed, the terminal device cannot learn such missing but would provide ACKs for

DAI

0, 1 and 2 as the HARQ feedback to the network device. Meanwhile, in the following PUCCH occasion, the HARQ feedback starts from 0 again and the network device cannot detect the missing of the assignment information regarding DAI=3 either. Thus, for the NR-U system, it will be desirable to use accumulated C-DAIs for example, within one PDSCH group. In other words, in PUCCH occasions belong to the same PDSCH group, the C-DAIs are accumulated. In such a way, the missed detection of DAI 2 can be learned by the terminal device from inconsecutive DAIs.

Fig. 2 illustrates a communication method according to embodiments of the present disclosure. The method can be performed at a terminal device like UE or any other terminal.

As illustrated in Fig. 2, in block 210, the terminal device may receive, from a network device, a feedback indication for a last transmitted HARQ feedback of the terminal device, the feedback indication indicating whether the last transmitted HARQ feedback was received. The last transmitted HARQ feedback used herein means the HARQ feedback, which should be last transmitted by the terminal device in the last or latest PUCCH occasion. The last transmitted HARQ feedback also means an HARQ feedback that the terminal device should transmit for the last or latest data transmitted by the network device. In embodiments of the present disclosure, the network device provides a feedback indication for the last transmitted HARQ feedback to tell the terminal device whether it receives the last transmitted HARQ feedback.

Then, in block 220, the terminal device may determine, based on the received feedback indication, a downlink assignment index (DAI) value starting from which another or new HARQ feedback is to be generated, wherein the DAI value is a next DAI value of a DAI corresponding to a last received HARQ feedback of the network device.

In view of the fact that the received feedback indication can indicate whether the last transmitted HARQ feedback is received, the terminal device can defer whether the last transmitted HARQ feedback is the last received HARQ feedback, and in turn determine the DAI corresponding to the last received HARQ feedback of the network device.

For example, if the received feedback indication indicates that the last transmitted HARQ feedback is received, it means the last transmitted HARQ feedback is the same as the last received HARQ feedback. In such a case, the DAI corresponding to the last transmitted HARQ feedback will be the same as the DAI corresponding to a last received HARQ feedback of the network device. For example, if the DAI corresponding to the last transmitted HARQ feedback is 1, then the DAI corresponding to the last received HARQ feedback of the network device is 1 too. Then, the starting DAI value for the new HARQ feedback, i.e., the DAI value starting from which another HARQ feedback is to be generated, will be the next value of the DAI corresponding to the last transmitted HARQ feedback.

On the other hand, if the received feedback indication indicates that the last transmitted HARQ feedback is not received, which means the last transmitted HARQ feedback is different from the last received HARQ feedback. In such a case, the DAI corresponding to a last received HARQ feedback of the network device will still be the DAI corresponding to the last transmitted HARQ feedback in the previous PUCCH occasion or still be an initial value 0 (in a case when no previous HARQ feedback is received by the network device) . For example, if the HARQ feedback for

DAIs

0 and 1 was transmitted in the first PUCCH occasion but the received feedback indicates that the last transmitted HARQ feedback is not received, then the starting DAI value for the new HARQ feedback shall still be 0. While if the HARQ feedback for

DAIs

1 and 2 was transmitted in the last PUCCH occasion and the received HARQ feedback indicates that the last transmitted HARQ feedback is not received, the last received HARQ feedback is still the last HARQ feedback transmitted in the previous PUCCH occasion and it corresponding DAI is 0. Therefore, the starting DAI value for the new HARQ feedback shall be the next value of DAI= 0, i.e. 1.

Thereafter, in block 230, the other or new HARQ feedback can be generated from the determined DAI. The operation of generating the HARQ feedback could utilize those solutions in the prior art and thus will not be elaborated herein.

Thus, in embodiments of the present disclosure, by means of feedback indication from the network device, the terminal device could determine the last HARQ feedback received by the network device and in turn determine the DAI from which a new HARQ feedback shall be generated. In other words, the new HARQ feedback starts from the next DAI of the last DAI, which is indicated as ‘received’ by the network device in, for example, DCI for the same PDSCH group. In addition, when there is no previous DAI received by the network device, the HARQ starts from DAI 0. Thus, it is possible to use accumulated DAI in the same PDSCH group by means of the feedback indication and in turn, robustness can be further improved especially for the NR-U system.

Hereinafter, only for illustrative purposes, reference will be made to Fig. 3 to describe an example method of determining a DAI value from which another HARQ feedback is to be generated according to embodiments of the present disclosure. However, it is to be appreciated that Fig. 3 is only given for illustrative purposes and the present disclosure is not limited thereto, the starting DAI value can be determined by any appropriate method.

As illustrated in Fig. 3, in block 310, the terminal device may determine determining a DAI value of the last transmitted HARQ feedback. For example, when the terminal device generates or transmits the HARQ feedback in a PUCCH occasion, it could record the corresponding DAI value of generated or transmitted HARQ feedback.

Then, in block 320, the terminal device may determine a DAI value of the last received HARQ feedback based on the determined DAI value of the last transmitted HARQ feedback and the received feedback indication. Thus, upon the receipt of the feedback indication, the terminal device may determine the DAI value of the last received HARQ feedback. For example, if the feedback indication indicates the last transmitted HRQ feedback is received, it could update the DAI value of the last received HARQ feedback with the determined DAI value of the last transmitted HARQ feedback; if not, it will maintain the DAI value of the last received HARQ feedback.

In block 330, the terminal device determines a next DAI value of the determined DAI value of the last received HARQ feedback as the DAI value starting from which the other HARQ feedback is to be generated. In view of the fact that the last transmitted HARQ is already received, then the HARQ feedback in the new PUCCH occasion shall start from the next one and the starting DAI is determined as a next DAI value of the determined DAI value of the last received HARQ feedback.

In some embodiments of the present disclosure, the terminal device may first determine a next DAI value of a DAI corresponding to the last transmitted HARQ feedback. Then based on the determined next DAI value of the DAI corresponding to the last transmitted HARQ feedback and the received feedback indication, the terminal device determines a next DAI value of a DAI corresponding to the last received HARQ feedback. The terminal device will take the next DAI value of a DAI corresponding to the last received HARQ feedback as the DAI value starting from which the other HARQ feedback is to be generated.

As an example, when the terminal device generates the dynamic HARQ-ACK codebook, V_temp, should be set based on the C-DAI (i.e., the DAI value of the last transmitted HARQ feedback) and a new feedback indication (NFI) . The parameter V_temp is similar to that in NR-system and indicates the staring DAI value of a PUCCH occasion and the NFI indicates the HARQ feedback in the latest PUCCH occasion was received by providing NFI with a value different from the previous one. In addition, a procedure of dynamic HARQ-ACK codebook generation is known and thus will not be detailed herein.

In an example embodiment of the present disclosure, two parameters V1 and V2 can be used, wherein V1 indicates a next DAI value of a DAI corresponding to the last transmitted HARQ feedback and V2 indicates a next DAI value of a DAI corresponding to the last received HARQ feedback. Initially, the UE may set V1 = 0 and V2 = 0. The terminal device updates V2 as the HARQ feedback is generated or transmitted. When the DCI toggles the feedback indication field NFI, it means the network receives the feedbacks, the terminal device may set V1 = V2, else maintain its value as it is. The V_temp can be set in accordance with V1.

For further illustrative purposes, Figs. 4A to 4C illustrate example HARQ feedback solutions according to embodiments of the present disclosure. As illustrated in 4A, initially, V1 and V2 are both initialized as 0. If The terminal device fails to detect assignment information of DAI 2 and it will transmit the HARQ feedback for

DAI

0, 1 in the first PUCCH occasion and update V2 =2. Due to the fact that NFI is changed from 0 to 1 in the following transmissions, the terminal device can learn that the network device already receives the HARQ feedback for HARQ DAIs 0 and 1, and then set V1=V2=2. Then, in the next PUCCH occasion, the HARQ will start from the value of V1, i.e. 2. In such a case, the HARQ feedback will be transmitted for DAI =2, 3 and 4. The terminal device could learn the missed detection of DAI from the inconsecutive DAIs and the corresponding feedback value for DAI 2 is NACK.

As illustrated in 4B, different from Fig. 4A, the NFI received from the network is not changed in the following transmission, and the terminal device can learn that the network device did not receive the HARQ feedback for HARQ DAIs 0 and 1. In such as case, the terminal device will not update V1 with V2, instead keep the V1 as it is. Then, in the next PUCCH occasion, the HARQ will start from the value of V1, i.e. 0. In such a case, the HARQ feedback will be transmitted for DAI =0, 1, 2, 3 and 4, and the corresponding feedback value for DAI 2 is NACK.

Different from Figs. 4A and 4B, Fig. 4C illustrates a middle part of PDSCH transmissions. As illustrated in Fig. 4C, the NFI received from the network is not changed either, and thus the terminal device can learn that the network device did not receive the HARQ feedback for HARQ DAIs 1 and 2. In such as case, the terminal device will not update V1 with V2, instead it keep the value of V1. Then, in the next PUCCH occasion, the HARQ will start from the value of V1, i.e. 1. In such a case, the HARQ feedback will be transmitted for DAI =1, 2, 3 and 4 and the corresponding feedback value for DAI 2 is NACK.

From the above description with reference with Fig. 4A to 4C, the terminal device can always know the missed detection of DAI-2 for each scenario. However, Figs. 4A to 4C are just given for illustrative purposes and the present disclosure is not limited thereto. Instead, the terminal device may use any other appropriate solutions to determine the DAI value starting from which the other HARQ feedback is to be generated.

In some embodiments of the present disclosure, the terminal device may determine a next DAI value of a DAI corresponding to the last transmitted HARQ feedback. Then, based on the determined next DAI value of the DAI corresponding to the last transmitted HARQ feedback and the received feedback indication, the terminal device determines a next DAI value of a DAI corresponding to the last received HARQ feedback as the DAI value starting from which the other HARQ feedback is to be generated.

In some embodiments of the present disclosure, when the terminal device generates the dynamic HARQ-ACK codebook, the staring DAI value V_temp should be set based on the C-DAI (i.e., the DAI value of the last transmitted HARQ feedback) and the NFI. For example, two parameters V1 and V2 can be used too but different from the solution described with reference to Fig. 4A to 4C, V1 indicates a DAI value corresponding to the last transmitted HARQ feedback and V2 indicates a DAI value corresponding to the last received HARQ feedback. Initially, the UE may set V1 = 0 and V2 = 0 and thereafter the terminal device can update V2 as the HARQ feedback is generated or transmitted. When the DCI toggles the feedback indication field NFI, it means the network receives the feedback, the terminal device may set V1 = V2, else maintain its value as it is. The V_temp can be set as V1+1 except when no previous HARQ feedback is received within the PDSCH group.

For further illustrative purposes, reference will be made to Figs. 5A to 5C to describe an example HARQ feedback solution according to embodiments of the present disclosure. Fig. 5A illustrates similar scenario to Fig. 4A but parameters V1 and V2 represent different meanings. Thus, when the terminal device fails to detect assignment information of DAI 2 and it will transmit the HARQ feedback for

DAI

0, 1 in the first PUCCH occasion and determines V2 as 1, i.e. the DAI corresponding to the last transmitted HARQ feedback. Due to the fact that NFI is changed from 0 to 1 in the following transmissions, the terminal device can learn that the network device already receives the HARQ feedback for HARQ DAIs 0 and 1, and then set V1=V2=1. Then, in the next PUCCH occasion, the HARQ will start from the DAI of V1+1, i.e. 2.

Fig. 5B illustrates similar scenario to Fig. 4B but parameters V1 and V2 represent different meanings. As illustrated in 5B, the NFI received from the network is not changed in the following transmission, the terminal device can learn that the network device did not receive the HARQ feedback for HARQ DAIs 0 and 1. In such as case, the terminal device will not update the value of V1. Then, in the next PUCCH occasion, the HARQ will just start from DAI 0 again due to no previously received HARQ feedback. In such a case, the new HARQ feedback will be transmitted for DAI =0, 1, 2, 3 and 4.

Fig. 5C illustrates similar scenario to Fig. 5C but parameters V1 and V2 represent different meanings. As illustrated in Fig. 5C, the NFI received from the network is not changed either, and thus the terminal device can learn that the network device did not receive the HARQ feedback for HARQ DAIs 1 and 2. In such as case, the terminal device will not update V1 with V2, but keep the value of V1. Then, in the next PUCCH occasion, the HARQ will start from the value of V1+1, i.e. 1. In such a case, the HARQ feedback will be transmitted for DAI =1, 2, 3 and 4.

It shall be appreciated that although examples are described with reference to Figs. 4A to Fig. 5C, the present disclosure is no limited thereto. It is possible to use any other appropriate methods to determine the starting DAI based on the feedback indication.

Fig. 6 further illustrates another communication method according to embodiments of the present disclosure. The communication method can be performed at a network device and one of its objects is to enhance the existing HARQ feedback solution in, for example, the NR-U system.

As illustrated in Fig. 6, in block 610, the network device may transmit a feedback indication for a last transmitted HARQ feedback of a terminal device to the terminal device, wherein the feedback indication indicates whether the last transmitted HARQ feedback was received. By means of the feedback indication for the last transmitted HARQ feedback, the network device can tell the terminal device whether it receives the last transmitted HARQ feedback. The terminal device may further utilize the feedback indication to determine the DAI of the last received HARQ feedback and in turn determine the starting DAI of the HARQ feedback to be generated.

In block 620, the network device receives another HARQ feedback from the terminal device. The another HARQ feedback was generated by the terminal device based on the transmitted feedback indication for the last transmitted HARQ feedback.

Then, in block 630, the network device determines, based on whether the last transmitted HARQ feedback was received, a DAI value starting from which the other HARQ feedback was generated wherein the DAI value is a next DAI value of a DAI corresponding to a last received HARQ feedback of the network device. That is to say, the network device will determine the starting DAI accordingly, for example in a similar way to the terminal device. For example, if the last transmitted HARQ feedback was received, the last received HARQ feedback can be determined as the last transmitted HARQ feedback; thus, the starting DAI can be determined as the next DAI value of the DAI corresponding to the last transmitted HARQ feedback. If not, the last received HARQ feedback can be determined as the last transmitted HARQ feedback in previous feedback transmission occasion; and thus the starting DAI can be determined as the next DAI value of the DAI corresponding to the last transmitted HARQ feedback in, for example, previous PUCCH occasion. For example, the network device could update the DAI value of the last received HARQ feedback if the last transmitted HARQ feedback was received and maintain the DAI value of the last received HARQ feedback if it was not received. Then it can just get the newest value of the last received HARQ feedback as the starting DAI.

In some other embodiments, there is further provided an improved one-short feedback solution. Different from legacy HARQ feedback solution in which the HARQ feedback is transmitted per HARQ-ACK feedback occasion, in the one-time HARQ-ACK feedback (for example HARQ-ACK feedback type 3) solution, the ACK/NACK is transmitted per HARQ identity ID. There might be two ways of determining the feedback value for a HARQ identity, which will be described with reference to Fig. 7.

As illustrated in Fig. 7, one way is to determine the feedback value as an ACK. However, in case of a DCI missed detection, neither the terminal device nor the network device could detect such missed detection, which is undesirable. The other way is set a default feedback value as NACK and reset the feedback value as the default feedback value. Thus, in case of DCI missed detection, the network device can perform data retransmit based on the NACK feedback. However, in such a case, it might cause a wrong feedback since the NACK cannot provide the real feedback value for the last transmission of the HARQ ID in case of no missed detection of DCI.

In addition, simultaneous one-time HARQ-ACK feedback and the dynamic HARQ-ACK feedback based on accumulated C-DAI could become more complex. For the dynamic HARQ-ACK feedback, missed detection of DCI can be inferred from C-DAI but the terminal device does not know the HARQ ID of the DCI and thus it still cannot know the missed detection.

Some solutions were proposed to use two bits to indicate ACK/NAVK value of the last received transmission concerning an HARQ identity and a corresponding NDI value respectively, but those solutions would double the number of bits for the one-time HARQ feedback and in turn cause a much higher signaling overhead.

In some embodiments, there is further provided an improved communication method and one of its objects is to address the above one-short HARQ feedback issue. Hereinafter, reference will be made to Figs. 8 to 10 to describe the improved communication method.

Fig. 8 illustrates a communication method for according to embodiments of the present disclosure. The communication method could be performed at the terminal device and one of it objects is to enhance the one-shot HARQ feedback solution in, for example, the NR-U system.

As illustrated in Fig. 8, in block 810, the terminal device will receive a one-shot HARQ feedback trigger information from the network device. Different from the dynamic HARQ feedback, the one shot feedback is trigger by DCI. If the terminal device determines that a one-short feedback transmission is trigged by the network device, the terminal device might generate a one-shot HARQ feedback with a feedback value for a HARQ identity indicating an expected new data indication (NDI) value of the terminal device in block 820.

In the NR system, the NDI is a new data indication, each time when the network transmits a new data, the network device will transmit a NDI with a value different from the last transmitted one. For example, if the last transmitted NDI is 0, the network device will transmit a NDI value of 1 to indicate a new data transmission and an NDI value of 0 to indicate a data retransmission. If the last transmitted NDI is 1, the network device will transmit a NDI value of 0 to indicate a new data transmission and an NDI value of 1 to indicate a data retransmission. The term “the expected NDI” means the NDI value that the terminal device expects to receive from the network device. The network device could learn the missed detection of DCI if the expected NDI is same as the current NDI or different from the NDI to be transmitted and learn the real feedback value of the last received data based on whether the NDI is changed. Only for illustrative purposes, reference will be made to Figs. 9A to 9D to describe several scenarios.

As illustrated in Fig. 9A, the last received data has HARQ ID=0, NDI =0 and the corresponding HARQ feedback is ACK. In such a case, the terminal device will expect a new data transmission. Thus, the expected NDI will be different from that of the last transmission, and it shall be 1. In a case when there is a missed detection of DCI as illustrated in the upper drawing of Fig. 9A, the network device can know the missed detection of DCI because the expected NDI is the same as the NDI of the already transmitted data. That is to say, the terminal device still expects the already transmitted data, which in turn means the already transmitted data is never received by the terminal device. On the other hand, if there is no missed detection of DCI as illustrated in lower drawing of Fig. 9A, the network device can also know that because the expected NDI will be the same as the NDI to be transmitted by the network device. In addition, from the expected NDI, the network device could learn that the HARQ of the last received data is ACK since it expects new data transmission.

As illustrated in Fig. 9B, the last transmission with HARQ ID=0, NDI =0 but the corresponding HARQ feedback is NACK. In such a case, the terminal device will expect a data retransmission. Thus, the expected NDI will be the same as the last transmission, and it is 0. In a case when there is a missed detection of DCI as illustrated in the upper drawing of Fig. 9B, the network device can know the missed detection of DCI because the expected NDI is the same as the NDI of the already transmission data, which means the terminal device still expects the already transmitted data. On the other hand, if there is no missed detection of DCI, the network device can also know that because the expected NDI will be the same as the NDI to be transmitted by the network device. In addition, from the expected NDI, the network device could learn that the HARQ of the last received data is NACK since it does not expect new data transmission.

Fig. 9C and Fig. 9D illustrates different scenarios in which NDI =1. In such a case, the expected value NDI of the terminals device will be different from those Fig. 9A and Fig. 9B. However, the network device could still learn the missed detection based on the expected NDI and this is because the network could know, from the expected NDI, whether the terminal device expects the already transmitted data or the data to be transmitted; in addition, the network device can also know whether the HARQ feedback of the last received data is ACK or NACK based on whether it expects new data transmission.

In some embodiments of the present disclosure, the feedback value for a HARQ identity is determined based on an acknowledge information of a last received transmission concerning the HARQ identity and a corresponding NDI value. As an example, the feedback value for a HARQ identity can be determined by performing an XOR operation on an acknowledge information of a last received transmission concerning the HARQ identity and the corresponding NDI value. According to the XOR operation, the resulting value will be 1 when the acknowledge information of the last received transmission concerning the HARQ identity is different from the corresponding NDI value and 0 when they are the same. By this means, the terminal device could generate the expected NDI value.

Fig. 10 illustrates a communication method 1000 according to embodiments of the present disclosure. The communication method could be performed at the terminal device and one of it objects is to enhance the one-shot HARQ feedback solution in, for example, the NR-U system.

As illustrated in Fig. 10, in block 1010, the network device transmits a downlink control indication to the terminal device, to trigger a one-short feedback transmission. Then, in block 1020, the network device receives a one-shot HARQ feedback from the terminal device. Different from the legacy one-shot HARQ feedback, the one-shot HARQ feedback has a feedback value for a HARQ identity indicating an expected NDI value of the terminal device. Based on the expected NDI value indicated by the feedback, the network performs the following data retransmission based on the expected NDI value and a current NDI value in block 1030. Similar to those described with reference to Fig. 8 to 9D, the network device could learn the missed detection from the expected NDI. Particularly, based on the expected NDI, the network could know whether the terminal device expects the already transmitted data or the data to be transmitted, if the terminal expects the already transmitted data, it means a missed detection of DCI. In addition, the network device can also know whether the HARQ feedback of the last received transmission is ACK or NACK based on whether the expected NDI changes from the previous one. If it is NACK, the network device will retransmit the last received transmission, or otherwise perform a new data transmission.

Hereinbefore,

methods

600 and 1000 implemented at the network device are described with reference to Figs. 6 and 10 in brief. However, it is to be appreciated that for details about the operations of

methods

600 and 1000, one may refer to descriptions of Figs. 1 to 5C and Figs. 7 to 9D.

In further aspects, apparatuses for performing the

method

200, 300, 600, 800 or 1000 may include means for performing respective steps of the

method

200, 300, 600, 800 or 1000. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

Hereinbefore, the apparatuses for performing

methods

200, 300, 600, 800 and 1000 are described in brief. It can be noted that for details about operations of these apparatuses, one may refer to descriptions of the respective steps of the methods with reference to Figs. 1 to 10.

In some embodiments of the present disclosure, there is provided a communication apparatus. The communication apparatus may be comprised or implemented in a terminal device and one of its purpose is to provide improved HARQ feedback solution. The communication apparatus may comprise means for receiving, from a network device, a feedback indication for a last transmitted Hybrid Automatic Repeat reQuest (HARQ) feedback of the terminal device, the feedback indication indicating whether the last transmitted HARQ feedback was received; means for determining, based on the received feedback indication, a downlink assignment index (DAI) value starting from which another HARQ feedback is to be generated, wherein the DAI value is a next DAI value of a DAI corresponding to a last received HARQ feedback of the network device; and means for generating the other HARQ feedback starting from the determined DAI.

In some embodiments of the present disclosure, the means for determining, based on the received feedback indication, a downlink assignment index (DAI) may be further configured to: determine a DAI value of the last transmitted HARQ feedback; determine a DAI value of the last received HARQ feedback based on the determined DAI value of the last transmitted HARQ feedback and the received feedback indication; and determine a next DAI value of the determined DAI value of the last received HARQ feedback as the DAI value starting from which the other HARQ feedback is to be generated.

In some embodiments of the present disclosure, the means for determining a DAI value of the last received HARQ feedback based on the determined DAI value of the last transmitted HARQ feedback and the received feedback indication may be further configured to: update the DAI value of the last received HARQ feedback with the determined DAI value of the last transmitted HARQ feedback in accordance with a determination that the received feedback indication is different from a previous one; or maintain the DAI value of the last received HARQ feedback in accordance with a determination that the received feedback indication is the same as the previous one.

In some embodiments of the present disclosure, the means for determining, based on the received feedback indication, a downlink assignment index (DAI) may be further configured to determine a next DAI value of a DAI corresponding to the last transmitted HARQ feedback; and determine, based on the determined next DAI value of the DAI corresponding to the last transmitted HARQ feedback and the received feedback indication, a next DAI value of a DAI corresponding to the last received HARQ feedback as the DAI value starting from which the other HARQ feedback is to be generated.

In some embodiments of the present disclosure, the means for determining, based on the determined next DAI value of the DAI corresponding to the last transmitted HARQ feedback and the received feedback indication, the next DAI value of the DAI corresponding to the last received HARQ feedback may be further configured to update the next DAI value of the DAI corresponding to the last received HARQ feedback with the determined next DAI value of the DAI corresponding to the last transmitted HARQ feedback in accordance with a determination that the received feedback indication is different from a previous one; or maintain the next DAI value of the DAI corresponding to the last received HARQ feedback in accordance with the determination that the received feedback indication is the same as the previous one.

In some embodiments of the present disclosure, the communication apparatus may further comprise means for generating a one-shot HARQ feedback with a feedback value for a HARQ identity indicating an expected new data indication (NDI) value of the terminal device in accordance with a determination that a one-short feedback transmission is trigged by the network device.

In some embodiments of the present disclosure, the feedback value for a HARQ identity may be determined based on an acknowledge information of a last received transmission concerning the HARQ identity and a corresponding NDI value.

In some embodiments of the present disclosure, the feedback value for a HARQ identity is determined by performing an XOR operation on an acknowledge information of a last received transmission concerning the HARQ identity and the corresponding NDI value.

In some embodiments of the present disclosure, there is provided another communication apparatus. The other communication apparatus may be comprised or implemented in a network device and one of its purposes is to provide improved HARQ feedback solution. The other communication apparatus may comprise means for transmitting a feedback indication for a last transmitted Hybrid Automatic Repeat reQuest (HARQ) feedback of a terminal device to the terminal device, the feedback indication indicating whether the last transmitted HARQ feedback was received; means for receiving another HARQ feedback from the terminal device; and means for determining a DAI value starting from which the other HARQ feedback was generated based on whether the last transmitted HARQ feedback was received, wherein the DAI value is a next DAI value of a DAI corresponding to a last received HARQ feedback of the network device.

In some embodiments of the present disclosure, the other communication apparatus may further comprise means for transmitting a downlink control indication to the terminal device, to trigger a one-short feedback transmission; means for receiving a one-shot HARQ feedback from the terminal device, the one-shot HARQ feedback having a feedback value for a HARQ identity indicating an expected NDI value of the terminal device; and means for performing data retransmission based on the expected NDI value and a current NDI value.

Those skilled in the art will appreciate that the aforesaid examples are only for illustration not limitation and the present disclosure is not limited thereto; one can readily conceive many variations, additions, deletions and modifications from the teaching provided herein and all these variations, additions, deletions and modifications fall the protection scope of the present disclosure.

In addition, in some embodiment of the present disclosure, these apparatuses may include at least one processor. The at least one processor suitable for use with embodiments of the present disclosure may include, by way of example, both general and special purpose processors already known or developed in the future. These apparatuses may further include at least one memory. The at least one memory may include, for example, semiconductor memory devices, e.g., RAM, ROM, EPROM, EEPROM, and flash memory devices. The at least one memory may be used to store program of computer executable instructions. The program can be written in any high-level and/or low-level compliable or interpretable programming languages. In accordance with embodiments, the computer executable instructions may be configured, with the at least one processor, to cause these apparatuses to at least perform operations according to the method as discussed with reference to Figs. 1 to 10 respectively.

Fig. 11 schematically illustrates a simplified block diagram of a communication system 1100 that can implement the communication methods according to embodiments of the present disclosure. The communication system 1100 include an apparatus 1110 that may be embodied as or included in a terminal device like UE described herein, an apparatus 1120 that may be embodied as or included in a network device like eNB or gNB.

The apparatus 1110 includes at least one processor 1111, such as a data processor (DP) and at least one memory (MEM) 1112 coupled to the processor 1111. The apparatus 1110 may further include a transmitter TX and receiver RX 1113 coupled to the processor 1111, which may be operable to communicatively connect to the apparatus 1120. The MEM 1112 stores a program (PROG) 1114. The PROG 1114 may include instructions that, when executed on the associated processor 1111, enable the apparatus 1110 to operate in accordance with embodiments of the present disclosure, for

example method

200, 300 or 800. A combination of the at least one processor 1111 and the at least one MEM 1112 may form processing means 1115 adapted to implement various embodiments of the present disclosure.

The apparatus 1120 includes at least one processor 1121, such as a DP, and at least one MEM 1122 coupled to the processor 1121. The apparatus 1120 may further include a suitable TX/RX 1123 coupled to the processor 1121, which may be operable for wireless communication with the apparatuses 1110. The MEM 1122 stores a PROG 1124. The PROG 1124 may include instructions that, when executed on the associated processor 1121, enable the apparatus 1120 to operate in accordance with the embodiments of the present disclosure, for example the

method

600 or 1000. A combination of the at least one processor 1121 and the at least one MEM 1122 may form processing means 1125 adapted to implement various embodiments of the present disclosure.

Various embodiments of the present disclosure may be implemented by computer program executable by one or more of the

processors

1111 and 1121 software, firmware, hardware or in a combination thereof.

The

MEMs

1112 and 1122 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples.

The

processors

1111 and 1121 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors DSPs and processors based on multicore processor architecture, as non-limiting examples.

In addition, the present disclosure may also provide a carrier containing the computer program as mentioned above, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium. The computer readable storage medium can be, for example, an optical compact disk or an electronic memory device like a RAM (random access memory) , a ROM (read only memory) , Flash memory, magnetic tape, CD-ROM, DVD, Blue-ray disc and the like.

The techniques described herein may be implemented by various means so that an apparatus implementing one or more functions of a corresponding apparatus described with an embodiment comprises not only prior art means, but also means for implementing the one or more functions of the corresponding apparatus described with the embodiment and it may comprise separate means for each separate function, or means that may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (one or more apparatuses) , firmware (one or more apparatuses) , software (one or more modules) , or combinations thereof. For a firmware or software, implementation may be made through modules (e.g., procedures, functions, and so on) that perform the functions described herein.

Exemplary embodiments herein have been described above with reference to block diagrams and flowchart illustrations of methods and apparatuses. It will be understood that each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations, respectively, can be implemented by various means including computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions which execute on the computer or other programmable data processing apparatus create means for implementing the functions specified in the flowchart block or blocks.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any implementation or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular implementations. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The above described embodiments are given for describing rather than limiting the disclosure, and it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the disclosure as those skilled in the art readily understand. Such modifications and variations are considered to be within the scope of the disclosure and the appended claims. The protection scope of the disclosure is defined by the accompanying claims.

Claims

A communication method, comprising:

at a terminal device,

receiving, from a network device, a feedback indication for a last transmitted Hybrid Automatic Repeat reQuest (HARQ) feedback of the terminal device, the feedback indication indicating whether the last transmitted HARQ feedback was received;

determining, based on the received feedback indication, a downlink assignment index (DAI) value starting from which another HARQ feedback is to be generated, wherein the DAI value is a next DAI value of a DAI corresponding to a last received HARQ feedback of the network device; and

generating the other HARQ feedback starting from the determined DAI.
The method of Claim 1, wherein the determining, based on the received feedback indication, a downlink assignment index (DAI) further comprises, at the terminal device:

determining a DAI value of the last transmitted HARQ feedback;

determining a DAI value of the last received HARQ feedback based on the determined DAI value of the last transmitted HARQ feedback and the received feedback indication; and

determining a next DAI value of the determined DAI value of the last received HARQ feedback as the DAI value starting from which the other HARQ feedback is to be generated.
The method of Claim 2, wherein the determining a DAI value of the last received HARQ feedback based on the determined DAI value of the last transmitted HARQ feedback and the received feedback indication further comprises:

updating the DAI value of the last received HARQ feedback with the determined DAI value of the last transmitted HARQ feedback in accordance with a determination that the received feedback indication is different from a previous one; or

maintaining the DAI value of the last received HARQ feedback in accordance with a determination that the received feedback indication is the same as the previous one.
The method of Claim 1, wherein the determining, based on the received feedback indication, a downlink assignment index (DAI) further comprises, at the terminal device:

determining a next DAI value of a DAI corresponding to the last transmitted HARQ feedback; and

determining, based on the determined next DAI value of the DAI corresponding to the last transmitted HARQ feedback and the received feedback indication, a next DAI value of a DAI corresponding to the last received HARQ feedback as the DAI value starting from which the other HARQ feedback is to be generated.
The method of Claim 4, wherein the determining, based on the determined next DAI value of the DAI corresponding to the last transmitted HARQ feedback and the received feedback indication, the next DAI value of the DAI corresponding to the last received HARQ feedback further comprises:

updating the next DAI value of the DAI corresponding to the last received HARQ feedback with the determined next DAI value of the DAI corresponding to the last transmitted HARQ feedback in accordance with a determination that the received feedback indication is different from a previous one; or

maintaining the next DAI value of the DAI corresponding to the last received HARQ feedback in accordance with the determination that the received feedback indication is the same as the previous one.
The method of any of Claims 1 to 5, further comprising, at the terminal device:

generating a one-shot HARQ feedback with a feedback value for a HARQ identity indicating an expected new data indication (NDI) value of the terminal device in accordance with a determination that a one-short feedback transmission is trigged by the network device.
The method of Claim 6, wherein the feedback value for a HARQ identity is determined based on an acknowledge information of a last received transmission concerning the HARQ identity and a corresponding NDI value.
The method of Claim 7, wherein the feedback value for a HARQ identity is determined by performing an XOR operation on an acknowledge information of a last received transmission concerning the HARQ identity and the corresponding NDI value.
A communication method, comprising:

at a network device,

transmitting a feedback indication for a last transmitted Hybrid Automatic Repeat reQuest (HARQ) feedback of a terminal device to the terminal device, the feedback indication indicating whether the last transmitted HARQ feedback was received;

receiving another HARQ feedback from the terminal device; and

determining a DAI value starting from which the other HARQ feedback was generated based on whether the last transmitted HARQ feedback was received, wherein the DAI value is a next DAI value of a DAI corresponding to a last received HARQ feedback of the network device.
The method of Claim 9, further comprising, at the network device:

transmitting a downlink control indication to the terminal device, to trigger a one-short feedback transmission;

receiving a one-shot HARQ feedback from the terminal device, the one-shot HARQ feedback having a feedback value for a HARQ identity indicating an expected NDI value of the terminal device; and

performing data retransmission based on the expected NDI value and a current NDI value.
A terminal device, comprising:

at least one processor; and

at least one memory coupled with the at least one processor;

the at least one memory having computer program codes therein which are configured to, when executed on the at least one processor, cause the terminal device at least:

receive, from a network device, a feedback indication for a last transmitted Hybrid Automatic Repeat reQuest (HARQ) feedback of the terminal device, the feedback indication indicating whether the last transmitted HARQ feedback was received;

determine, based on the received feedback indication, a downlink assignment index (DAI) value starting from which another HARQ feedback is to be generated, wherein the DAI value is a next DAI value of a DAI corresponding to a last received HARQ feedback of the network device; and

generate the other HARQ feedback starting from the determined DAI.
The terminal device of Claim 11, wherein the computer program codes are further configured to, when executed on the at least one processor, cause the terminal device to determine the downlink assignment index (DAI) starting from which another HARQ feedback is to be generated by:

determining a DAI value of the last transmitted HARQ feedback;

determining a DAI value of the last received HARQ feedback based on the determined DAI value of the last transmitted HARQ feedback and the received feedback indication; and

determining a next DAI value of the determined DAI value of the last received HARQ feedback as the DAI value starting from which the other HARQ feedback is to be generated.
The terminal device of Claim 12, wherein the computer program codes are further configured to, when executed on the at least one processor, cause the terminal device to determine the DAI value of the last received HARQ feedback by:

updating the DAI value of the last received HARQ feedback with the determined DAI value of the last transmitted HARQ feedback in accordance with a determination that the received feedback indication is different from a previous one; or

maintaining the DAI value of the last received HARQ feedback in accordance with a determination that the received feedback indication is the same as the previous one.
The terminal device of Claim 11, wherein the computer program codes are further configured to, when executed on the at least one processor, cause the terminal device to determine the downlink assignment index (DAI) starting from which another HARQ feedback is to be generated by:

determining a next DAI value of a DAI corresponding to the last transmitted HARQ feedback; and

determining, based on the determined next DAI value of the DAI corresponding to the last transmitted HARQ feedback and the received feedback indication, a next DAI value of a DAI corresponding to the last received HARQ feedback as the DAI value starting from which the other HARQ feedback is to be generated.
The terminal device of Claim 14, wherein the computer program codes are further configured to, when executed on the at least one processor, cause the terminal device to determine the DAI value of the last received HARQ feedback by:

updating the next DAI value of the DAI corresponding to the last received HARQ feedback with the determined next DAI value of the DAI corresponding to the last transmitted HARQ feedback in accordance with a determination that the received feedback indication is different from a previous one; or

maintaining the next DAI value of the DAI corresponding to the last received HARQ feedback in accordance with the determination that the received feedback indication is the same as the previous one.
The terminal device of any of Claims 11 to 15, wherein the computer program codes are further configured to, when executed on the at least one processor, cause the terminal device to:

generate a one-shot HARQ feedback with a feedback value for an HARQ identity indicating an expected new data indication (NDI) value of the terminal device in accordance with a determination that a one-short feedback transmission is trigged by the network device.
The terminal device of Claim 16, wherein the computer program codes are further configured to, when executed on the at least one processor, cause the terminal device to determine the feedback value for a HARQ identity based on an acknowledge information of a last received transmission concerning the HARQ identity and a corresponding NDI value.
The terminal device of Claim 17, wherein the computer program codes are further configured to, when executed on the at least one processor, cause the terminal device to determine the feedback value for a HARQ identity by performing an XOR operation on an acknowledge information of a last received transmission concerning the HARQ identity and the corresponding NDI value.
A network device, comprising:

at least one processor; and

at least one memory coupled with the at least one processor;

the at least one memory having computer program codes therein which are configured to, when executed on the at least one processor, cause the network device at least to:

transmit a feedback indication for a last transmitted HARQ feedback of a terminal device to the terminal device, the feedback indication indicating whether the last transmitted HARQ feedback was received;

receive another HARQ feedback from the terminal device; and

determine a DAI value starting from which the other HARQ feedback was generated based on whether the last transmitted HARQ feedback was received, wherein the DAI value is a next DAI value of a DAI corresponding to a last received HARQ feedback of the network device.
The network device of Claim 19, the computer program codes are further configured to, when executed on the at least one processor, cause the network device to:

transmit a downlink control indication to the terminal device, to trigger a one-short feedback transmission;

receive a one-shot HARQ feedback from the terminal device, the one-shot HARQ feedback having a feedback value for an HARQ identity indicating an expected NDI value of the terminal device; and

perform data retransmission based on the expected NDI value and a current NDI value.
A computer readable medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to perform the method of any of Claims 1-8.
A computer readable medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to perform the method of Claim 9 or 10.