WO2023285193A1 - Communications devices, network nodes, circuitry, systems and methods - Google Patents

Abstract

A method for managing acknowledgments in a telecommunications network, the telecommunications network comprising a network node arranged to communicate with a communications device via a wireless interface. The method comprises determining, by the network node, that one or more acknowledgement feedbacks have not been received from the communications device; transmitting, by the network node and to the communications device, a retransmission request; transmitting, by the network node and to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, the communications device determining whether it has received a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more acknowledgement feedbacks to be retransmitted; and the communications device reporting feedback information to the network node, the feedback information being identified based on the indication. If the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received

Description

Communications devices, network nodes, circuitry, systems and methods

The present application claims the Paris Convention priority of European patent application EP21185436.9, filed 13 July 2021, the contents of which are hereby incorporated by reference.

Field

The present disclosure relates to communications devices, network nodes, circuitry, systems and methods. Examples of the present disclosure can be particularly useful for transmitting and/or receiving acknowledgements in a mobile telecommunications network.

Background

The "background" description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.

Latest generation mobile telecommunication systems are able to support a wider range of services than simple voice and messaging services offered by earlier generations of mobile telecommunication systems. For example, with the improved radio interface and enhanced data rates provided by LTE systems, a user is able to enjoy high data rate applications such as mobile video streaming and mobile video conferencing that would previously only have been available via a fixed line data connection. The demand to deploy such networks is therefore strong and the coverage area of these networks, i.e. geographic locations where access to the networks is possible, is expected to continue to increase rapidly.

Future wireless communications networks will be expected to efficiently support communications with an ever-increasing range of devices and data traffic profiles than existing systems are optimised to support. For example, it is expected future wireless communications networks will be expected to efficiently support communications with devices including reduced complexity devices, machine type communication devices, high resolution video displays, virtual reality headsets and so on. Some of these different types of devices may be deployed in very large numbers, for example low complexity devices for supporting the "The Internet of Things", and may typically be associated with the transmissions of relatively small amounts of data with relatively high latency tolerance.

In view of a desire to support new types of devices with a variety of applications there is expected to be a desire for future wireless communications networks, for example those which may be referred to as 5G or new radio (NR) systems / new radio access technology (RAT) systems, as well as future iterations / releases of existing systems, to efficiently support connectivity for a wide range of devices associated with different applications and different characteristic data traffic profiles and requirements.

Example use cases currently considered to be of interest for next and latest generation wireless communication systems include so-called Ultra Reliable and Low Latency Communications (URLLC) / enhanced Ultra Reliable and Low Latency Communications (eURLLC). See, for example, the 3GPP documents RP-160671, "New SID Proposal: Study on New Radio Access Technology," NTT DOCOMO, RAN#71 [1]; RP-172834, "Work Item on New Radio (NR) Access Technology," NTT DOCOMO, RAN#78 [2]; RP-182089, "New SID on Physical Layer Enhancements for NR Ultra-Reliable and Low Latency Communication (URLLC)," Huawei, HiSilicon, Nokia, Nokia Shanghai Bell, RAN#81 [3]; and RP-190654, "Physical layer enhancements for NR ultra-reliable and low latency communication (URLLC)," Huawei, HiSilicon, RAN#89, Shenzhen, China, 18 to 21 March 2019 [4],

URLLC services are low latency and high reliability services (e.g. to support applications such as factory automation, transport industry, electrical power distribution etc.). URLLC services might, for example, aim to transmit data through a radio network with a target 32-byte packet transit time (i.e. time from ingress of a layer 2 packet to its egress from the network) of 1 ms (i.e. so that each packet needs to be scheduled and transmitted across the physical layer in a time that is shorter than 1 ms) with 99.999% reliability within the 1 ms target packet transit time [5], and there are recent proposals for this to be increased to 99.9999% with a latency between 0.5 ms and 1 ms.

The 3GPP project has recently completed a Release-16 Work Item on eURLLC [6] to specify features that require high reliability and low latency such as factory automation, transport industry, electrical power distribution, etc. in a 5G system. The eURLLC feature is further enhanced in Release-17 in a new Work Item [7], where one of the objectives is to enhance acknowledgment signalling (HARQ-ACK feedback) in respect of URLLC downlink transmissions.

Application EP 20187799.0 filed 24 July 2020 [10], the contents of which are incorporated herein by reference, also provides techniques for managing acknowledgement messages and may be of interest to the skilled reader.

Summary

The invention is defined in the independent claims. Further example embodiments are provided in the dependent claims.

According to a first aspect of the present disclosure, there is provided a method for managing acknowledgments in a telecommunications network, the telecommunications network comprising a network node arranged to communicate with a communications device via a wireless interface. The method comprises determining, by the network node, that one or more acknowledgement feedbacks have not been received from the communications device; transmitting, by the network node and to the communications device, a retransmission request; transmitting, by the network node and to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, the communications device determining whether it has received a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more acknowledgement feedbacks to be retransmitted; and the communications device reporting feedback information to the network node, the feedback information being identified based on the indication. If the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received. According to a second aspect of the present disclosure, there is provided a system for acknowledgement retransmission in a telecommunications network, the telecommunications network comprising a network node arranged to communicate with a communications device via a wireless interface, the system comprising the network node and the communications device. The network node is configured to determine that one or more acknowledgement feedbacks have not been received from the communications device; transmit, to the communications device, a retransmission request; and transmit, to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted. The communications device is configured to determine, upon receiving the retransmission request and using the indication, whether it has received a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more acknowledgement feedbacks to be retransmitted; and report feedback information to the network node, the feedback information being identified based on the indication. If the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received.

According to a third aspect of the present disclosure, there is provided a method of operating a network node in a telecommunications network, the network node being configured to communicate with a communications device of the telecommunications network via a wireless interface. The method comprises determining that one or more acknowledgement feedbacks have not been received from the communications device; transmitting, to the communications device, a retransmission request; transmitting, to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; and receiving, from the communications device and in response to the retransmission request, a report comprising feedback information.

According to a fourth aspect of the present disclosure, there is provided a network node for use in a telecommunications network, the network node comprising a transceiver element and controller configured to operate together to provide a wireless interface and to communicate with a communications device of the telecommunications network via the wireless interface. The transceiver element and controller being further configured to determine that one or more acknowledgement feedbacks have not been received from the communications device; transmit, to the communications device, a retransmission request; transmit, to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; and receive, from the communications device and in response to the retransmission request, a report comprising feedback information.

According to a fifth aspect of the present disclosure, there is provided circuitry for a network node for use in a mobile telecommunications network, the network comprising a communications device and the network node, the network node being configured to provide a wireless interface to the communications device, wherein the circuitry comprises a controller element and a transceiver element configured to operate together to communicate with the communications device via the wireless interface and wherein the controller element and the transceiver element are further configured to operate together to determine that one or more acknowledgement feedbacks have not been received from the communications device; transmit, to the communications device, a retransmission request; transmit, to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; and receive, from the communications device and in response to the retransmission request, a report comprising feedback information.

According to a sixth aspect of the present disclosure, there is provided a method of operating a communications device in a telecommunications network, the telecommunications network comprising a network node arranged to communicate with the communications device via a wireless interface, the method comprising: receiving, from the network node, a retransmission request; receiving, from the network node, an indication indicating one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, determining whether a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more first acknowledgement feedback has been received; and reporting feedback information to the network node. If the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received.

According to a seventh aspect of the present disclosure, there is provided a communications device for use in a telecommunications network, the communications device comprising a transceiver element and controller configured to operate together to communicate with a network node of the telecommunications network via a wireless interface provided by the network node. The transceiver element and controller are further configured to receive, from the network node, a retransmission request; receive, from the network node, an indication indicating one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, determine whether a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more first acknowledgement feedback has been received; and report feedback information to the network node. If the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received.

According to an eighth aspect of the present disclosure, there is provided circuitry for a communications device for use in a mobile telecommunications network, the network comprising the communications device and a network node configured to provide a wireless interface to the communications device, wherein the circuitry comprises a controller element and a transceiver element configured to operate together to communicate with the network node via the wireless interface and wherein the controller element and the transceiver element are further configured to operate together to receive, from the network node, a retransmission request; receive, from the network node, an indication indicating one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, determine whether a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more first acknowledgement feedback has been received; and report feedback information to the network node. If the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received. According to a ninth aspect of the present disclosure, there is provided a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of any one of the first, third and sixth aspects above.

It is to be understood that both the foregoing general description and the following detailed description are illustrative, but are not restrictive, of the present technology. The described examples devices, systems or methods of the present disclosure, together with associated teachings, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

Brief description of the drawings

A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein like reference numerals designate identical or corresponding parts throughout the several views, and wherein:

Figure 1 schematically represents some aspects of an example LTE-type wireless telecommunication network;

Figure 2 schematically represents some aspects of an example new radio (NR) access technology (RAT) wireless telecommunications network;

Figure 3 schematically represents an example telecommunications system;

Figures 4 to 9 schematically show example uses of radio resources associated with a communications device in an uplink grid of radio communications resources (top half of figure) and downlink grid of radio communications resources (bottom half of figure);

Figures 10 to 20 schematically show example uses of radio resources associated in accordance with the examples of the present disclosure; and

Figure 21 illustrates an example method in accordance with the present disclosure.

In the following description, reference is made to the accompanying drawings which illustrate several examples of the present disclosure. It is to be understood that other examples may be implemented and system or method changes may be made without departing from the teachings of the present disclosure. The following detailed description is not to betaken in a limiting sense, and the scope of the embodiments of the present invention is defined only by the claims. It is to be understood that drawings are not necessarily drawn to scale. Some examples of the present disclosure may not fall within the scope of the claims but are useful for understanding the technical field of the invention and the teachings of the present disclosure. Description of Examples

Long Term Evolution Advanced Radio Access Technology

Figure 1 provides a schematic diagram illustrating some basic functionality of a mobile telecommunications network / system 100 operating generally in accordance with LTE principles, but which may also support other radio access technologies, and which may be adapted to implement embodiments of the disclosure as described herein. Various elements of Figure 1 and certain aspects of their respective modes of operation are well-known and defined in the relevant standards administered by the 3GPP (RTM) body, and also described in many books on the subject, for example, Flolma H. and Toskala A [9] It will be appreciated that operational aspects of the telecommunications (or simply, communications) networks discussed herein which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to the relevant standards and known proposed modifications and additions to the relevant standards.

The network 100 includes a plurality of base stations 101 connected to a core network 102. Each base station provides a coverage area 103 (i.e. a cell) within which data can be communicated to and from terminal devices 104. Data is transmitted from base stations 101 to terminal devices 104 within their respective coverage areas 103 via a radio downlink (DL). Data is transmitted from terminal devices 104 to the base stations 101 via a radio uplink (UL). The core network 102 routes data to and from the terminal devices 104 via the respective base stations 101 and provides functions such as authentication, mobility management, charging and so on. Terminal devices may also be referred to as mobile stations, user equipment (UE), user terminal, mobile radio, communications device, and so forth. Base stations, which are an example of network infrastructure equipment / network access node, may also be referred to as transceiver stations / nodeBs / e-nodeBs / eNBs / g-nodeBs / gNBs and so forth. In this regard different terminology is often associated with different generations of wireless telecommunications systems for elements providing broadly comparable functionality. Flowever, certain embodiments of the disclosure may be equally implemented in different generations of wireless telecommunications systems, and for simplicity certain terminology may be used regardless of the underlying network architecture. That is to say, the use of a specific term in relation to certain example implementations is not intended to indicate these implementations are limited to a certain generation of network that may be most associated with that particular terminology.

New Radio Access Technology (5G)

Figure 2 is a schematic diagram illustrating a network architecture for a new RAT wireless communications network / system 200 based on previously proposed approaches which may also be adapted to provide functionality in accordance with embodiments of the disclosure described herein. The new RAT network 200 represented in Figure 2 comprises a first communication cell 201 and a second communication cell 202. Each communication cell 201, 202, comprises a controlling node (centralised unit) 221, 222 in communication with a core network component 210 over a respective wired or wireless link 251, 252. The respective controlling nodes 221, 222 are also each in communication with a plurality of distributed units (radio access nodes / remote transmission and reception points (TRPs)) 211, 212 in their respective cells. Again, these communications may be over respective wired or wireless links. The distributed units (DUs) 211, 212 are responsible for providing the radio access interface for communications devices connected to the network. Each distributed unit 211, 212 has a coverage area (radio access footprint) 241, 242 where the sum of the coverage areas of the distributed units under the control of a controlling node together define the coverage of the respective communication cells 201, 202. Each distributed unit 211, 212 includes transceiver circuitry for transmission and reception of wireless signals and processor circuitry configured to control the respective distributed units 211, 212.

In terms of broad top-level functionality, the core network component 210 of the new RAT communications network represented in Figure 2 may be broadly considered to correspond with the core network 102 represented in Figure 1, and the respective controlling nodes 221, 222 and their associated distributed units / TRPs 211, 212 may be broadly considered to provide functionality corresponding to the base stations 101 of Figure 1. The term network infrastructure equipment / access node may be used to encompass these elements and more conventional base station type elements of wireless communications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may lie with the controlling node / centralised unit and / or the distributed units / TRPs.

A communications device or UE 260 is represented in Figure 2 within the coverage area of the first communication cell 201. This communications device 260 may thus exchange signalling with the first controlling node 221 in the first communication cell via one of the distributed units 211 associated with the first communication cell 201. In some cases communications for a given communications device are routed through only one of the distributed units, but it will be appreciated in some other implementations communications associated with a given communications device may be routed through more than one distributed unit, for example in a soft handover scenario and other scenarios.

In the example of Figure 2, two communication cells 201, 202 and one communications device 260 are shown for simplicity, but it will of course be appreciated that in practice the system may comprise a larger number of communication cells (each supported by a respective controlling node and plurality of distributed units) serving a larger number of communications devices.

It will further be appreciated that Figure 2 represents merely one example of a proposed architecture for a new RAT communications system in which approaches in accordance with the principles described herein may be adopted, and the functionality disclosed herein may also be applied in respect of wireless communications systems having different architectures.

Thus example embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems / networks according to various different architectures, such as the example architectures shown in Figures 1 and 2. It will thus be appreciated the specific wireless communications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, example embodiments of the disclosure may be described generally in the context of communications between network infrastructure equipment / access nodes and a communications device, wherein the specific nature of the network infrastructure equipment / access node and the communications device will depend on the network infrastructure for the implementation at hand. For example, in some scenarios the network infrastructure equipment / access node may comprise a base station, such as an LTE-type base station 101 as shown in Figure 1 which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment / access node may comprise a control unit / controlling node 221, 222 and / or a TRP 211, 212 of the kind shown in Figure 2 which is adapted to provide functionality in accordance with the principles described herein.

A more detailed illustration of a UE 270 and an example network infrastructure equipment 272, which may be thought of as a gNB 101 or a combination of a controlling node 221 and TRP 211, is presented in Figure 3. As shown in Figure 3, the UE 270 is shown to receive downlink data from the infrastructure equipment 272 via resources of a wireless access interface as illustrated generally by an arrow 274. The UE 270 receives the downlink data transmitted by the infrastructure equipment 272 via communications resources of the wireless access interface (not shown). As with Figures 1 and 2, the infrastructure equipment 272 is connected to a core network 276 via an interface 278 to a controller 280 of the infrastructure equipment 272. The infrastructure equipment 272 includes a receiver 282 connected to an antenna 284 and a transmitter 286 connected to the antenna 284. Correspondingly, the UE 270 includes a controller 290 connected to a receiver 292 which receives signals from an antenna 294 and a transmitter 296 also connected to the antenna 294.

The controller 280 is configured to control the infrastructure equipment 272 and may comprise processor circuitry which may in turn comprise various sub-units / sub-circuits for providing functionality as explained further herein. These sub-units may be implemented as discrete hardware elements or as appropriately configured functions of the processor circuitry. Thus the controller 280 may comprise circuitry which is suitably configured / programmed to provide the desired functionality using conventional programming / configuration techniques for equipment in wireless telecommunications systems. The transmitter 286 and the receiver 282 may comprise signal processing and radio frequency filters, amplifiers and circuitry in accordance with conventional arrangements. The transmitter 286, the receiver 282 and the controller 280 are schematically shown in Figure 3 as separate elements for ease of representation. Flowever, it will be appreciated that the functionality of these elements can be provided in various different ways, for example using one or more suitably programmed programmable computer(s), or one or more suitably configured application-specific integrated circuit(s) / circuitry / chip(s) / chipset(s). As will be appreciated the infrastructure equipment 272 will in general comprise various other elements associated with its operating functionality.

Correspondingly, the controller 290 of the UE 270 is configured to control the transmitter 296 and the receiver 292 and may comprise processor circuitry which may in turn comprise various sub-units / sub circuits for providing functionality as explained further herein. These sub-units may be implemented as discrete hardware elements or as appropriately configured functions of the processor circuitry. Thus the controller 290 may comprise circuitry which is suitably configured / programmed to provide the desired functionality using conventional programming / configuration techniques for equipment in wireless telecommunications systems. Likewise, the transmitter 296 and the receiver 292 may comprise signal processing and radio frequency filters, amplifiers and circuitry in accordance with conventional arrangements. The transmitter 296, receiver 292 and controller 290 are schematically shown in Figure 3 as separate elements for ease of representation. However, it will be appreciated that the functionality of these elements can be provided in various different ways, for example using one or more suitably programmed programmable computer(s), or one or more suitably configured application-specific integrated circuit(s) / circuitry / chip(s) / chipset(s). As will be appreciated the communications device 270 will in general comprise various other elements associated with its operating functionality, for example a power source, user interface, and so forth, but these are not shown in Figure 3 in the interests of simplicity.

The controllers 280, 290 may be configured to carry out instructions which are stored on a computer readable medium, such as a non-volatile memory. The processing steps described herein may be carried out by, for example, a microprocessor in conjunction with a random access memory, operating according to instructions stored on a computer readable medium.

Example Services

As mentioned above, there are a variety of services which may be supported by wireless communications networks. Development of physical layer, radio access and media access protocols and techniques can be adapted to support such services. Example services which are being defined for 5G/New Radio (NR) are the Ultra-Reliable and Low Latency Communications (URLLC) and the enhanced Mobile BroadBand (eMBB) services. URLLC has very low latency and high reliability where a URLLC data packet (e.g. 32 bytes) is required to be transmitted from the radio protocol layer ingress point to the radio protocol layer egress point of the radio interface within 1 ms with a reliability of 99.999% [5] to 99.9999%. On the other hand, eMBB requires high data rate of for example 20 Gbps with moderate latency and reliability (e.g. 99% to 99.9%).

Example developments for 3GPP are eURLLC [6] and NR Unlicensed (NR-U) [8], For the example of eURLLC proposals have been made to specify features for high reliability and low latency services such as factory automation, transport industry, electrical power distribution, etc. in a 5G system. Unlicensed radio frequency resources refer to a concept in which the radio resources are not exclusively allocated to a particular operator or radio communications system but are shared between systems, which to some extent compete for these resources. An example application for unlicensed spectrum is a 3GPP Release- 16 NR-U work item which specifies features which include incorporating Listen Before Talk (LBT) in NR frame structure to enable NR operation in unlicensed bands.

PDSCH HARQ-ACK Feedbacks

Certain embodiments of the disclosure relate to apparatus and methods for handling acknowledgment signalling (e.g. HARQ-ACK signalling) in respect of transmissions of data in a wireless telecommunications system. Acknowledgment signalling is used in wireless telecommunications systems to indicate whether a transmission was successfully received or not. If the transmission was successfully received the receiving entity will send positive acknowledgment signalling (i.e. an ACK), and if the transmission was not successfully received the intended recipient entity will send negative acknowledgment signalling (i.e. a NACK). The term acknowledgment signalling will be used herein to refer collectively to both positive acknowledgment signalling (i.e. ACK) and negative acknowledgment signalling (i.e. NACK).

For scheduled transmission of data from a network access node (base station) to a communications device in a wireless telecommunications system it is common for the network access node to first send control signalling, e.g. on a downlink control channel (such as a PDCCH - Physical Downlink Control Channel), comprising downlink control information (DCI) which indicates (grants) downlink radio resources that are to be used to transmit the data, e.g. on a downlink shared channel (such as a PDSCH). From this the communications device can determine uplink radio resources to use to send uplink control information (UCI) comprising acknowledgment signalling in respect of the data, e.g. on an uplink control channel (such as a PUCCFI), although it may also be on an uplink shared channel (such as a PUSCFI). The communications device then seeks to receive the data on the indicated radio resources on the downlink shared channel. If the communications device successfully decodes the data it transmits a UCI on the determined uplink radio resources comprising an ACK indication, and if the communications device does not successfully decode the data it transmits a UCI on the determined uplink radio resources comprising a NACK indication. This allows the network access node to determine if it should schedule a retransmission of the data.

So as to provide some particular examples, certain embodiments of the disclosure will be described herein in the context of acknowledgement signalling for downlink transmissions of URLLC data and using terminology, for example in respect of channel names such as PUCCFI and PDSCFI and signalling names, such as DCI and UCI, which are typically used in connection with current 3GPP wireless telecommunications systems. Flowever, it will be appreciated this is only for convenience, and in general the approaches discussed herein are applicable for other service types and in wireless telecommunications systems which use different terminology. Thus, references herein to PUCCFI should, unless the context demands otherwise, be read as referring to a physical uplink control channel generally, and not specifically to a particular format of physical uplink control channel, and so on for other channels and terminology that may be referred to herein.

FIARQ-ACK (FHybrid Automatic Repeat Request acknowledgement signalling) feedback is transmitted by a communications device to a base station in respect of PDSCFI scheduling to inform the base station whether the communications device has successfully decoded the corresponding PDSCFI or not. Radio resources in wireless telecommunications resources comprise a grid of resources (i.e. a radio frame structure) spanning frequency and time. The frequency dimension is divided into sub-carriers and the time dimension is divided into symbols that are grouped into slots.

In some current systems, for a PDSCFI ending in slot n, the corresponding PUCCFI carrying the FIARQ-ACK acknowledgement signalling is transmitted in slot n+Ki, where the value of Ki is indicated in the field "PDSCFI-to-FIARQ_feedback timing indicator" in the downlink (DL) Grant for the PDSCFI (carried by DCI (downlink control information) Format 1_0 or DCI Format 1_1). Multiple (different) PDSCFIs can point to the same slot for transmission of their respective FIARQ-ACKs, and multiple FIARQ-ACKs in the same slot can be multiplexed into a single PUCCFI. Flence a PUCCFI can contain multiple FIARQ-ACKs for multiple PDSCFIs. An example of this is represented Figure 4. Figure 4 schematically shows an uplink radio resource grid (top half of figure) and downlink radio resource grid (bottom half of figure) representing radio resources in time (horizontal axis) and frequency (vertical axis). Figure 4 schematically shows radio resources used by a communications device In an example, scenario during a period spanning five slots (identified in Figure 4 as slots n to n+4). In slot n the communications device receives downlink control information (DCI#1) indicating an allocation of radio resources on a physical downlink shared channel (PDSCFI#1) in slot n+1 with a PDSCFI-to-FIARQ_feedback timing indicator value of Ki = 3 and a "PUCCFI Resource Indicator" (PRI) field indicating resources in the first half of the slot (i.e. PUCCFI#1 in Figure 4). In slot n+1 the communications device receives downlink control information (DCI#2) indicating an allocation of radio resources on a physical downlink shared channel (PDSCFI#2) in slot n+2 with a PDSCFI-to-FIARQ_feedback timing indicator value of Ki = 2 and a PRI field indicating the same resources in the first half of the slot as for DCI#1 (i.e. PUCCFI#1). In slot n+2 the communications device receives downlink control information (DCI#3) indicating an allocation of radio resources on a physical downlink shared channel (PDSCFI#3) in slot n+3 with a PDSCFI-to-FIARQ_feedback timing indicator value of Ki = 1 and a PRI field indicating resources in the second half of the slot (i.e. PUCCFI#2 in Figure 4). Thus, in this particular example scenario, the FIARQ-ACK feedbacks for each of the three downlink transmissions on the physical downlink shared channel are scheduled to be transmitted by the communications device in slot n+4 and so can be transmitted in a multiplexed manner. To support this multiplexed FIARQ-ACK function a Multiplexing Window may be defined, wherein the Multiplexing Window is a time window indicating how many PDSCFIs can have their associated FIARQ-ACK signalling multiplexed in PUCCFI in a single slot and may depend on the range of Ki values. In the example in Figure 4, the PUCCFI Multiplexing Window is assumed to be from Slot n to Slot n+3, which means the max Ki value that can be used in this period is 4.

In some systems (e.g. Release-15 system), only one PUCCFI per slot is allowed to carry FIARQ-ACKs for the same communications device even if the different PUCCFIs do not overlap in time. In these systems, the PUCCFI resource is indicated in the "PUCCH Resource Indicator" (PRI) field in the downlink Grant. Each downlink Grant may indicate a different PUCCFI resource, but the communications device will follow the PRI indicated in the last PDSCH in the PUCCFI Multiplexing Window since the communications device only knows the total number of FIARQ-ACK bits after the last PDSCFI is received.

The operation of such a system is illustrated in Figure 5, where DCI#1 and DCI#2 indicate PUCCFI#1 for the HARQ-ACKs corresponding to PDSCH#1 and PDSCH#2, but DCI#3 indicates PUCCH#2 for the HARQ-ACK corresponding to PDSCFI#3. Flere, PUCCFI#1 and PUCCFI#2 do not overlap in time. Using the technique mentioned above of having only one uplink control transmission per time unit (e.g. slot) for transmitting acknowledgement feedback and since in this example DCI#3 schedules the last PDSCFI (PDSCFI#3), in the Multiplexing Window, the communications device will use PUCCFI#2 to carry the FIARQ-ACK for PDSCFIffl, PDSCFI#2 and PDSCFI#3. It will be appreciated that in such system other uplink control transmissions, e.g. a PUCCFI carrying other UCI such as a SR (Scheduling Request), may be transmitted separately from a PUCCFI carrying FIARQ-ACK feedback within the same time unit (e.g. slot), in particular if they do not overlap in time.

For other systems (e.g. systems in accordance with Release 16 of the 3GPP standards), the possibility of sub-slot operation for FIARQ-ACK acknowledgement signalling was introduced. Sub-slot operation for HARQ-ACK allows the timings of HARQ-ACK UCI on PUCCH to be configured with a resolution which is less than one slot (i.e. the HARQ-ACK process operates with sub-slot timing granularity). Sub-slot based PUCCH thus allows more than one PUCCH carrying HARQ-ACKs to be transmitted within a slot. This provides for more opportunities for PUCCH carrying HARQ-ACK in respect of PDSCH transmissions to be transmitted within a slot, thereby potentially helping to reduce the latency of HARQ-ACK feedback. In a sub-slot based PUCCH, the granularity of the Ki parameter (i.e. the time difference between the end of PDSCH and the start of its corresponding PUCCH) is in units of sub-slot instead of slot, where the sub-slot size can be 2 symbols or 7 symbols. An example of sub-slot HARQ-ACK operation is shown in Figure 6.

Figure 6 is similar to, and will be understood from, Figure 5, but this example schematically shows an uplink radio resource grid (top half of figure) and downlink radio resource grid (bottom half of figure) representing radio resources in time (horizontal axis) and frequency (vertical axis) in a scenario that support sub-slot operation for HARQ-ACK feedback with a sub-slot size of 7 symbols (i.e. half a slot in this case). Thus Figure 6 schematically shows radio resources used by a communications device In an example, scenario during a period spanning five slots (identified in Figure 6 as slots n to n+4) / ten sub-slots (identified in Figure 6 as sub-slots m to m+9). In sub-slot m the communications device receives downlink control information (DCI#1) indicating an allocation of radio resources on a physical downlink shared channel (PDSCHffl) in sub-slot m+2 with a PDSCH-to-HARQ_feedback timing indicator value of Ki = 6. This means the communications device determines the resources PUCCHffl to use for transmitting acknowledgement signalling in respect of PDSCHffl as indicated by the PRI associated with DCffl in sub slot m+8 (since this is the sub-slot which is Ki = 6 sub-slots after the sub-slot in which PDSCHffl ends). In sub-slot m+2 the communications device receives downlink control information (DCI#2) indicating an allocation of radio resources on a physical downlink shared channel (PDSCH#2) that spans sub-slots m+4 and m+5 with a PDSCH-to-HARQ_feedback timing indicator value of Ki = 4. This means the communications device determines the resources PUCCH#2 to use for transmitting acknowledgement signalling in respect of PDSCH#2 as indicated by the PRI associated with DCI#2 in sub-slot m+9 (since this is the sub-slot which is Ki = 4 sub-slots after the sub-slot in which PDSCH#2 ends). In contrast to approaches according to the systems discussed above (e.g. according to Release 15 of the 3GPP standards specification series), where only one PUCCH carrying HARQ-ACK is allowed in a slot, in a sub-slot based operation, a communications device can transmit two PUCCH carrying HARQ-ACK (i.e. PUCCHffl and PUCCH#2) in a slot.

Semi-Persistent Scheduling of PDSCHs

In Semi-Persistent Scheduling (SPS) PDSCH, the PDSCH resources are pre-configured (e.g. via RRC signalling) and occur periodically where each SPS PDSCH occasion has a pre-configured and fixed duration. This allows the network node or gNB to schedule traffic that has a known periodicity and packet size. The network node or gNB may or may not transmit any PDSCH in the SPS PDSCH occasion and so the UE needs to monitor each SPS PDSCH occasion for potential PDSCH transmission.

In some systems (e.g. defined in Release 15), the communications device can only be configured with one SPS PDSCH and this SPS PDSCH is activated using an activation control signal, where the control signal may be a DCI (Format 1_0 or 1_1) with the CRC scrambled with CS-RNTI. Once an SPS PDSCH is activated, the communications device will monitor for potential PDSCH in each SPS PDSCH occasion of the SPS PDSCH configuration without the need for any downlink Grant until the SPS PDSCH is deactivated. Deactivation of the SPS PDSCH can be indicated via a deactivation control signal, which can for example be a DCI scrambled with the communications device's CS-RNTI. In this particular arrangement, the communications device will provide an acknowledgment (e.g. HARQ-ACK) feedback for the deactivation DCI but no HARQ-ACK feedback is provided for an activation DCI.

Similar to Dynamic Grant PDSCH (DG-PDSCH), the slot containing the PUCCH resource for HARQ-ACK corresponding to SPS PDSCH is indicated using the /Ci value in the field " PDSCH-to-HARQ_feedback timing indicator" of the activation DCI. Since DG Grant is not used for SPS PDSCH, this Ki value is applied for every SPS PDSCH occasion and can only be updated after it has been deactivated and re-activated using another activation DCI with a different Ki value.

In this example system, since there is only one SPS PDSCH that can be configured at the same time, PUCCH Format 0 or 1 can be used to carry the HARQ-ACK feedback. If the PUCCH collides with a PUCCH carrying HARQ-ACK feedbacks for DG-PDSCH, the HARQ-ACK for SPS PDSCH can be multiplexed into the PUCCH corresponding to DG-PDSCH.

In other systems (e.g. defined in Release 16), the communications device can be configured with up to eight Semi-Persistent Scheduling (SPS) PDSCHs, where each SPS PDSCH has an SPS Configuration Index that is RRC configured. Each SPS PDSCH can be individually activated using a control signal. The control signal may for example be a DCI (e.g. Format 1_0, 1_1 & 1_2) with the CRC scrambled with CS-RNTI, where it indicates the SPS Configuration Index of the SPS PDSCH to be activated. On the other hand, multiple SPS PDSCHs may be deactivated using a single deactivation control signal (e.g. DCI). Similar to systems discussed above (e.g. Release-15 systems), the communications device can provide a HARQ-ACK feedback for the deactivation DCI, however it may not have to provide one for the activation DCI.

The time period, e.g. slot or sub-slot, containing the PUCCH resource for HARQ-ACK feedback corresponding to a SPS PDSCH occasion is determined using the Ki value indicated in the activation control signal (e.g. DCI). Since in this example, each SPS PDSCH configuration is individually activated, different SPS PDSCH can be indicated with different Ki values.

Figure 7 illustrates an example with a SPS system where acknowledgement feedback is multiplexed. Since different Ki values can be used for different SPS PDSCH configurations, it is possible that the HARQ-ACK for multiple SPS PDSCHs point to the same slot or sub-slot. In this case, these HARQ-ACKs can be multiplexed into a single PUCCH. In some systems and for multiple SPS PDSCH configurations, PUCCH Format 2, 3 & 4 (in addition to PUCCH Format 0 & 1) can be used to carry multiple HARQ-ACKs for SPS PDSCH. In some cases, the HARQ-ACK feedbacks in the uplink transmission (e.g. uplink control transmission PUCCH) can be sorted in ascending order according to the downlink slot for each of the SPS PDSCH Configuration Index and then sorted in ascending order of the SPS PDSCH Configuration Index. As the skilled person will appreciate, as the Ki value is usually fixed per SPS PDSCH, more than one SPS PDSCHs with the same index is unlikely to have their acknowledgement feedbacks being multiplexed into a single PUCCH. However SPS PDSCH having different index might have their associated acknowledgement feedbacks be multiplexed in the same uplink resources. An example is shown in Figure 7, where a communications device is configured with 3 SPS PDSCHs labelled as SPS#1, SPS#2 and SPS#3 with SPS Configuration Index 1, 2 and 3 respectively, and in this case, with different periodicities (although in some cases they may have the same periodicity). For example, their respective periodicities may be configured via RRC signalling. SPS#1, SPS#2 and SPS#3 are activated with Ki=3, Ki=4 and Ki=l respectively. These Ki values result in the PUCCFI for FIARQ-ACK feedbacks corresponding to SPS#2 in Slot n, SPS#1 in Slot n+1 and SPS#3 in Slot n+3 to be in the same slot, i.e. carried by PUCCFI#2 in Slot n+4. PUCCFI#1 will provide a single acknowledgement feedback for SPS#1. On the other hand, PUCCH#2 will provide three HARQ-ACKs labelled as {ACK#1, ACK#2, ACK#3} for SPS#1, SPS#2 and SPS#3 respectively according to their SPS PDSCFI Configuration Indices. It will also be appreciated that this example, there is only one unique SPS PDSCFI transmission per downlink slot that have FIARQ- ACK multiplexed into PUCCFI#2, namely a SPS#1 PDSCFI (from Ϊ to ts), a SPS#2 PDSCFI (from Ϊ to U) and a SPS#3 PDSCFI (from tio to tn).

Uplink LI Priority Indicator

Certain embodiments as described in the following paragraphs may concern a different priority indicator when uplink resources are allocated to a UE for uplink transmissions. A priority indicator for uplink transmissions has been proposed for 3GPP standards, in which a different priority is allocated for uplink transmissions where these uplink transmissions collide and so one must be chosen over the other. In some systems, such as previous versions of 3GPP standards (e.g. Release 15), there was no provision for a different priority level at the Physical Layer and when two uplink transmissions collide, information for uplink transmissions is multiplexed and transmitted using a single channel. Possible collisions of uplink resources can include a PUCCFI with PUCCFI and PUCCFI with PUSCFI. In this respect the collision occurs and can be identified at the physical layer. For example, Release 15 systems and other systems were configured to provide different priority levels for the media access control layer, which included sixteen priority levels, but not the physical layer.

As explained above, a UE can be configured to provide eMBB and URLLC services contemporaneously. Since eMBB and URLLC have different latency requirements, their uplink transmissions may collide. For example, after an eMBB uplink transmission has been scheduled, an urgent URLLC packet arrives which would need to be scheduled immediately and its transmission may collide with the eMBB transmission. In order to handle such intra-UE collisions with different latency and reliability requirements, two priority levels at the physical layer have been proposed in Release-16 for Uplink transmissions, such as for example transmissions via PUCCFI and PUSCFI channels. In Release-16 intra-UE prioritisation is used, that is, when two UL transmissions with different Physical Layer priority levels (LI priority) collide, the UE will drop the lower priority transmission. If both UL transmissions have the same LI priority then the UE is configured to multiplex the transmissions according to that proposed in Release-15 procedures. The gNB indicates the LI priority to the UE in the 1 bit "Priority indicator" DCI field, where "0" indicates Low LI priority and "1" indicates FHigh LI priority and:

• For PUSCFI, the LI priority is indicated in the uplink grant carried by DCI Format 0_1 and 0_2

• For PUCCFI carrying FIARQ-ACK feedback for PDSCFI, the LI priority is indicated in the Downlink grant scheduling a PDSCFI, carried by DCI Format 1_1 and 1_2 According to these examples therefore, the downlink control information (DCI) carries a priority level indicator associated with the uplink transmission associated with the downlink transmission for which resources are being granted by the downlink control information, and the indicator may be different for different DCI formats depending on whether the downlink control information scheduling a PUSCH or a PUCCH.

HARQ-ACK Codebook

HARQ-ACK codebook is used to carry multiple HARQ-ACK feedbacks for PDSCH. In Release-15 there are two types of HARQ-ACK codebooks:

• Type 1 HARQ-ACK codebook: Also known as semi-static HARQ-ACK codebook where the number of HARQ-ACK entries is fixed, i.e. semi-statically configured by RRC. Since the HARQ-ACK entries are fixed, there is no confusion between UE and gNB on the number of HARQ-ACK feedbacks the UE should transmit to the gNB if the UE missed a downlink grant (i.e. missed a PDSCH). However, allocated a fixed number of HARQ-ACK feedbacks can waste resources since PDSCH that are not scheduled are still being feedback as NACK.

• Type 2 HARQ-ACK codebook: Also known as dynamic HARQ-ACK codebook where the number of HARQ-ACK entries is dynamic and based on the actual number of PDSCH being received. To avoid confusion on the number of HARQ-ACK feedbacks due to UE missing Downlink grants a "Downlink Assignment Index” (DAI) is used to keep track of the number of PDSCH transmitted to the UE. The DAI is included in the Downlink grant and is incremented when the gNB schedules a PDSCH to the UE using Type 2 HARQ-ACK codebook.

Since the PUCCH can have two LI priorities, two HARQ-ACK codebooks of different priorities can be configured for a UE. This allows High LI priority HARQ-ACKs to be multiplexed into a High LI priority HARQ-ACK codebook and Low LI priority HARQ-ACKs to be multiplexed into a Low LI priority HARQ-ACK codebook.

An example is shown in Figure 8 which illustrates an arrangement in which two HARQ-ACK codebooks are provided with two different priorities. In the example shown in Figure 8, the gNB transmits to the UE in a PDCCH (downlink control channel) a sequence of four downlink control information transmissions DCI#1, DCI#2, DCI#3, DCI#4, which respectively indicate an allocation of downlink resources PDSCHffl, PDSCH#2, PDSCH#3, PDSCH#4 respectively. As indicated in Figure 8, two of the downlink control information transmissions DCI#1, DCI#2 schedule a Low LI priority PUCCHffl in sub-slot m+8 which carries a Low LI priority HARQ-ACK codebook to multiplex the HARQ-ACK feedbacks for PDSCHffl and PDSCH#2 as represented by arrows . In contrast the second two downlink control information transmissions DCI#3, DCI#4 schedule a High LI priority PUCCH#2 in sub-slot m+9 which carries a High LI priority HARQ-ACK codebook to multiplex the HARQ-ACK feedbacks for PDSCH#3 and PDSCH#4. Hence, according to this example, the gNB can use different PUCCH that can have different reliability to carry HARQ-ACK with different LI priorities. Priority and missed downlink control signal

In some cases an uplink control or data transmission (e.g. PUCCH or PUSCH) carrying acknowledgement feedback (e.g. HARQ-ACKs) for PDSCHs may be cancelled due to intra-UE LI prioritisation, for example if it collides with a higher priority uplink transmission (e.g. PUCCH or PUSCH). A UE's uplink transmission (e.g. control, data, PUCCH, PUSCH transmission) can also be cancelled by an UpLink (UL) Cancellation Indicator due uplink inter-UE prioritisation. For example, a lower priority uplink transmission from a UE may collide with a higher priority uplink transmission from another UE and an UL Cancellation Indicator may be indicated by the gNB to cancel the transmission of the UE with lower priority uplink transmission. In some TDD systems, a UE's uplink control transmission (e.g. PUCCH) for SPS PDSCH acknowledgement may also be cancelled if it collides with downlink symbols or invalid symbols.

A cancelled PUCCH that contains multiple HARQ-ACKs may lead to the retransmission of multiple PDSCHs since the base station (e.g. gNB) is not aware of the decoding status of these PDSCHs and is therefore likely to assume these were not successfully received. This would lead to inefficient use of resource especially if the UE had successfully decoded most of these PDSCHs.

Recognising the limitations associated with a cancelled HARQ-ACKs, in some systems (e.g. Release 17 for URLLC transmissions), techniques have been introduced to retransmit cancelled HARQ-ACKs. These techniques include considering enhancing the Type 3 HARQ-ACK Codebook to reduce its associated overhead and a new Dynamic HARQ-ACK Codebook for retransmitting cancelled HARQ-ACKs.

The Type 3 HARQ-ACK Codebook had been introduced with unlicensed spectrums (e.g. NR-U) in mind to trigger a UE to retransmit its HARQ-ACKs due to unsuccessful previous uplink (e.g. PUCCH or PUSCH) HARQ-ACK transmission(s) expected to occur as a result of a LBT (Listen Before Talk) failure. Such a Type 3 HARQ-ACK Codebook is triggered using a downlink control signal, in particular it has been suggested using the 1 bit DCI field "One-shot HARQ-ACK request" (1-shot) in DCI Format 1_1, which indicates to the UE to transmit PDSCH HARQ-ACK feedbacks for all configured HARQ processes, regardless whether the HARQ-ACK has been transmitted previously or failed to transmit due to failed LBT attempt. For further description of Type 3 HARQ-ACK Codebook, the content of [10], which is incorporated herein by reference, may be of interest. While this may provide benefits in an unlicensed environment, there is a relatively high overhead associated with such a technique, in particular regarding acknowledgement which have already been successfully transmitted.

However, as the size of the Type 3 HARQ-ACK Codebook is semi-statically configured, the overhead reduction may not be optimal as the number of cancelled HARQ-ACK occurs dynamically (as discussed for example in Reference [11]) and is unlikely to be accurately predictable.

Another approach is to consider whether a new HARQ-ACK Codebook with a dynamic size may be used to carry only HARQ-ACK for feedback retransmissions, e.g. following a feedback transmission cancellation. In such a feedback retransmission technique which can be viewed as another HARQ-ACK Codebook, which we will refer to herein as "Retransmission HARQ-ACK Codebook" or "ReTx CB", a feedback retransmission may be triggered by a retransmission request. For example, it may be triggered by a control signal (e.g. DCI) which may be similar to that used for Type 3 HARQ-ACK Codebook. However, there may be some cases where there may be discrepancies between the number of retransmitted feedbacks expected and the ones actually transmitted. For example, if the UE misses a downlink Grant, it may not be aware that it is expected to send a further acknowledgement message.

An example illustrating a discrepancy between the number of acknowledgement transmitted and expected is illustrated in Figure 9. In this example, downlink Grants DCI#1, DCI#2 and DCI#3 schedule PDSCHffl, PDSCH#2 and PDSCH#3 respectively. The HARQ-ACK for PDSCHffl and PDSCH#2 are scheduled to be carried by PUCCHffl which has a Low LI priority whilst the HARQ-ACK for PDSCH#3 is scheduled in PUCCH#2 which as a High LI priority. In this example, PUCCHffl and PUCCH#2 collide and since PUCCHffl has lower LI priority, it is cancelled and PUCCH#2, carrying acknowledgement feedback for higher priority transmissions, can be transmitted.

In this example the UE missed DCI#2 (e.g. did not receive it or did not manage to successfully decode it) and is thus unaware of the expected presence of an additional acknowledgement (HARQ-ACK) in (cancelled) PUCCHffl. Even if the gNB transmits DCI#4 as a retransmission request to trigger the UE to retransmit the cancelled HARQ-ACK feedback, in a further uplink transmission (e.g. PUCCH#3), it would retransmit only one HARQ-ACK for PDSCHffl (Ai) as the UE had missed DCI#2. On the other hand, the gNB will expect two acknowledgement feedbacks (HARQ-ACKs), namely for PDSCHffl and for PDSCH#2. Furthermore, the gNB is not expected to be able to determine whether the received acknowledgement (which is HARQ-ACK Ai in this example), is associated with PDSCHffl or with PDSCH#2. This issue causes a mismatch between the number of retransmitted HARQ-ACK between gNB and UE and as a result the gNB will most likely retransmit both PDSCHffl and PDSCH#2. While in some cases, such a retransmission request may result in a successful retransmission of all of the expected acknowledgements, in other cases (like the one illustrated in Figure 9), this will have merely delayed the retransmission of PDSCHffl and PDSCH#2 and created an overhead without having an associated benefit.

According to techniques discussed herein, there is provided an arrangement in which a retransmission request is sent to the communications device which identifies at least one of the HARQ ACKs that the base station has not received.

Retransmission request - (HARQ-ACK) Indication

The identifier included in the retransmission request can for example be referred to as a HARQ-ACK indication, where the indication provides information for the UE to determine the number and/or identification of HARQ-ACKs for which retransmission has been requested.

Different example implementations and techniques are provided below wherein two or more of these techniques may be combined, for example to combine the expected benefits associated with each technique.

In one example, the HARQ-ACK indication indicates the number of cancelled HARQ-ACK

that the UE needs to retransmit. An example is shown in Figure 10, which is similar to that in Figure 9 but in this case, the retransmission request or trigger (ReTx CB) send in a downlink control signal (DCI#4 in this example) also indicates the number of HARQ-ACKs to be retransmitted, namely two feedbacks to be retransmitted in this case.

The UE believed that it had one HARQ-ACK transmission that had been cancelled (for PDSCHffl) and to retransmit because it had missed the Downlink Grant (DCI#2) but the indication identifies two HARQ-ACKs and so the UE is aware that it has missed a Downlink Grant. Rather than the UE being oblivious to the fact that there is a discrepancy between the number of acknowledgement feedbacks it was planning on retransmitting after the cancellation and the number of expected acknowledgement feedbacks to be received.

In this example the UE can retransmit two HARQ-ACK one for PDSCHffl and another for an unknown transmissions, e.g. PDSCH, (which is unknown at least from the UE's perspective). This is illustrated in Figure 10 where the uplink transmission scheduled by the retransmission request is used to transmit the acknowledgment feedback for PDSCHffl (which is either positive or negative), and a negative acknowledgement feedback for the unknown downlink transmission (PDSCH#2 in Figure 10). It will be appreciated that techniques and teachings below may be also be used for the base station (gNB in this example) to associate the received feedback (Ai and L/2 in Figure 10) with the corresponding downlink transmissions (PDSCHffl or PDSCH#2).

In another embodiment, the (HARQ-ACK) indication indicates the number of cancelled PUCCH,

It will be noted that this example differs from the above example in that the number of cancelled uplink acknowledgment transmission(s) is identified, rather than the number of acknowledgement feedbacks scheduled to be carried in the cancelled transmissions. This is because each uplink transmission (e.g. PUCCH) may carry one or more acknowledgement feedbacks, for example in the form of a HARQ-ACK Codebook which may contain multiple HARQ-ACKs, such that a single PUCCH may carry two or more HARQ-ACKs. It will also be appreciated that this example may be combined with the previous example (and other examples below) such that they are not mutually exclusive.

An example is shown in Figure 11, where Downlink Grants DCIffl, DCI#2, DCI#3 and DCI#4 schedule PDSCHffl, PDSCH#2, PDSCH#3 and PDSCH#4 respectively. The HARQ-ACKs for PDSCHffl, PDSCH#2, PDSCH#3 and PDSCH#4 are scheduled to be transmitted in PUCCHffl, PUCCH#2, PUCCH#3 and PUCCH#4 respectively, where PUCCHffl and PUCCH#3 have Low LI priority (LP) whilst PUCCH#2 and PUCCH#4 have High LI priority (HP). PUCCHffl and PUCCH#3 collide and since PUCCHffl has lower priority it is cancelled, while PUCCH#2 is transmitted.

Likewise, PUCCH#3 is dropped when it collides with PUCCH#4. PUCCHffl and PUCCH#3 carry HARQ-ACK Codebooks CBi and CB3 respectively, which may carry HARQ-ACKs for multiple PDSCHs (not shown in Figure 11). In this example, the UE misses DCI#3 and so is not aware that PDSCH#3 is scheduled. However, the UE may be aware that PUCCH#3 is scheduled since PUCCH#3 may carry HARQ-ACK for other PDSCHs in the HARQ-ACK Codebook. The gNB then sends the retransmission request DCI#5 which triggers for a ReTx CB to be transmitted using PUCCH#5. As per this embodiment, DCI#5 also indicates

= 2 and hence the UE is to retransmit the HARQ-ACKs from the HARQ-ACK Codebooks carried by these two PUCCHs, i.e. CBi and CBi. The UE therefore retransmits the HARQ-ACKs from CBi and CBi in PUCCH#5. It will be appreciated that this example may also be combined with other examples, for example, where the retransmission request includes the number of acknowledgement feedback to retransmit. The retransmission request may for example include a number of feedbacks of four or more, as the base station is expecting at least Al, A2 and A3, as well as the one or more HARQ-ACK feedbacks scheduled to be carried by PUCCH#3. This may be for example be useful for cases where the UE may not be able to determine how many HARQ-ACK were scheduled to be transmitted in PUCCH#3 (e.g. in a Type-2 codebook or similar arrangement). It will also be appreciated that in some cases (e.g. in a case of a Type-1 codebook or similar arrangement), the uplink transmission PUCCH#3 may be of a fixed size which is related to the number of HARQ-ACK to be transmitted in the uplink transmission. Accordingly, the UE can determine how many HARQ-ACK feedbacks were scheduled to be sent in PUCCH#3 and thus derive how many were missed. Additionally, in cases where the UE missed DCI#3 and wasn't aware that PUCCH#3 was scheduled at all, it can then determine, using the indication, that it has missed at least one grant for a downlink transmission and corresponding uplink grant(s) for uplink transmission(s), for sending the acknowledgment feedback for the missed downlink transmission(s). Additionally and optionally, in cases where the UE is able to determine how many grants (and corresponding transmissions) have been missed, the UE can send a corresponding number of negative feedback(s). Additionally or alternatively, in cases where the US is not able to determine how many grants have been missed, it can send information devoid of any specific positive or negative feedback (e.g. NULL feedback, as discussed below).

In another example, the HARQ-ACK indication can indicate the number of cancelled groups or sets of acknowledgement feedbacks, e.g. HARQ-ACK Codebooks, A/_Cg. The groups or sets of acknowledgement feedback can for example be feedbacks to be multiplexed in the same uplink transmission. The UE can then be configured to retransmit the HARQ-ACK contained in these cancelled HARQ-ACK Codebooks. This embodiment is similar to that where the HARQ-ACK indication is the number of cancelled PUCCH but in this embodiment recognizes that acknowledgement feedbacks (e.g. HARQ-ACK Codebooks) can sometimes also be carried by uplink data transmissions (e.g. PUSCH), for example when HARQ-ACKs are multiplexed into a PUSCH, and that the PUSCH may also be cancelled due to collision with Higher LI priority transmissions or with DL symbol (in TDD).

In another example, the indication can alternatively or additionally indicate the Type of the cancelled groups of acknowledgements or HARQ-ACK Codebook to be retransmitted. The HARQ-ACK Codebook can have a fixed size, e.g. Type 1 HARQ-ACK Codebook or a dynamic size, e.g. Type 2 or e-Type 2 HARQ-ACK Codebook. This example is beneficial for cases where they are more than one cancelled HARQ-ACK Codebook and the gNB only wants only a subset of the cancelled HARQ-ACK Codebooks to be retransmitted. Again and according to the techniques proposed herein, by using the indication, the UE can determine how to report the acknowledgment feedbacks, for example based on a determination of whether there may be discrepancies between the number of acknowledgement feedbacks outstanding for the terminal and the number expected by the base station.

In another example, the trigger for ReTx CB includes a Downlink Assignment Index (DAI) counter which identifies the last downlink transmission for which acknowledgement(s) have to be retransmitted. This may be particularly useful in cases where the cancelled PUCCH or PUSCH carry(ies) a dynamic HARQ-ACK Codebook such as Type 2 or e-Type 2 HARQ-ACK Codebook as the number of outstanding feedbacks may be more difficult to determine in these cases. In current systems, the DAI is a counter transmitted in a Downlink Grant for the UE to keep track of the number of PDSCH scheduled so that the UE could feedback the correct number of HARQ-ACK feedback in a dynamic HARQ-ACK Codebook. There are two types of DAI's, i.e., Counter DAI (C-DAI) and Total DAI (T- DAI), where typically the C-DAI is the 2 most significant bits and T-DAI is the 2 least significant bits of the DAI field. T-DAI is used in multi-carrier operation. C-DAI consists of 2 bits, which is incremented whenever a PDSCH is scheduled for the UE. When the number of PDSCH exceeds 4, the counter wraps around to 0. The UE can keep track of the counter and of the number of times C-DAI wraps around and by doing so can determine the number of PDSCH being scheduled. As long as the UE does not miss 4 or more consecutive Downlink Grants, the UE is able to keep track of the number of scheduled PDSCH. More information on DAI may be found in [12], the contents of which are incorporated herein by reference. It will also be appreciated that other implementations of counters may be used with this technique, where the indication can comprise an index of a downlink transmission for which an acknowledgement is requested to be retransmitted.

This example recognises that if the UE misses the last Downlink Grant, it would have a mismatch in the number of HARQ-ACK feedbacks to the gNB. Hence, by providing the last DAI, e.g. the C-DAI to the UE, the UE may be able to determine the number of HARQ-ACK feedback.

This is illustrated in Figure 12, where DCI#1, DCI#2 and DCI#3 schedule PDSCHffl, PDSCH#2 and PDSCH#3 with their corresponding HARQ-ACKs scheduled to a Low LI priority PUCCHffl carried by a (dynamic) Type 2 HARQ-ACK Codebook. PDSCHffl is the first PDSCH sharing the same Type 2 HARQ-ACK Codebook with PDSCH#2 & PDSCH#3 and so in the Downlink Grant carried by DCIffl, the C-DAI = 00 and, using the index, the UE notes (internally) that the number of received

1. Similarly, DCI#2 which schedules PDSCH#2 increases the C-DAI = 01 and the UE updates

The UE did not detect DCI#3 and at this point the UE thinks that only 2 PDSCHs have been sent by the gNB. DCI#4 schedules PDSCH#4 where its HARQ-ACK is transmitted in a High LI priority PUCCH#2, which collides with PUCCHffl. Consequently, PUCCHffl is cancelled.

The base can then send a retransmission request, e.g. by sending DCI#5 which triggers a ReTx CB and as per this example, it also signals the last C-DAI, i.e. C-DAI=10. Since the indicated last C-DAI does not match the UE recorded

the UE knows that it has missed the last Downlink Grant (or Grants if the discrepancy in counter value or index is two or more). Accordingly, the UE can update its

accordingly, = 3 in this example. The UE then retransmits the cancelled HARQ-ACKs for PDSCHffl, PDSCH#2 and PDSCH#3 where PDSCH#3 is a NACK. It will be appreciated that if the last C-DAI is not signalled in DCI#5 that triggers the ReTx CB and unless another technique is used, the UE is likely to assume that only 2 PDSCHs were transmitted by the gNB and there would have been a discrepancy in the number of HARQ-ACKs expected versus the number retransmitted.

It will also be appreciated that, even in an arrangement where the downlink transmission index is used to try to avoid discrepancies, it may be transmitted at least in part outside of the retransmission request. For example, the last DAI counter of a scheduled PDSCH with a LP PUCCH carrying its HARQ-ACK may be repeated in the Downlink Grant scheduling a HP PUCCH that collides with the LP PUCCH. This last DAI counter may be transmitted in each Downlink Grant scheduling HP PUCCH or only in some of these Downlink Grants, e.g. the last Downlink Grant scheduling a PDSCH with a corresponding HP PUCCH. This recognizes that Downlink Grants scheduling HP PUCCH are better protected (i.e. with robust MCS) than low priority ones and hence has a higher chance of being received by the UE and that the gNB is likely to be able to anticipate, at that stage, that the HP PUCCH will collide with the LP PUCCH (and that a retransmission request is likely to be sent shortly). This would also reduce the load of the ReTx CB which can implicitly refer to the indication previously transmitted (with the index) and/or which may include a further portion of the indication (e.g. it may be used to provide further indications or information as described in other examples provided herein).

This example may also be beneficial if the UCI in the LP PUCCH is multiplexed with the HP PUCCH, as it would help ensure that the UE is aware of the number of LP HARQ-ACK when multiplexing with HP HARQ- ACK.

An example is illustrated in Figure 13, which has the same scenario as that in Figure 12 but instead of (or "in addition to") repeating the Last LP C-DAI in the retransmission request ReTx, the gNB repeats the Last LP C-DAI in DCI#4 that schedules PDSCH#4 with a corresponding HP PUCCH#2. This enables the UE to check whether it has missed a Downlink Grant for LP PUCCH and to handle any future (and possibly likely) retransmission request. Using the indication send for a higher priority downlink transmission, e.g. in the Downlink Grant or DCI for this transmission, the communications device can better identify which acknowledgements may be outstanding for the gNB. For example, upon receipt of the index in the high priority downlink transmission (e.g. in the grant for the transmission), the UE can adjust its number of LP HARQ-ACK accordingly and retransmit them in the ReTx CB in PUCCH#3.

In another example, the HARQ-ACK indication indicates the location(s) of the cancelled uplink transmission(s), such as PUCCH or PUSCH. The UE retransmits the HARQ-ACK or the Codebooks carried by these indicated PUCCH/PUSCH. In a case where the UE was not aware that a PUCCH or PUSCH had been scheduled, the UE can report that it has not received the corresponding downlink transmission. As above, depending on whether the UE can determine how many downlink transmissions were missed or not received, the UE may report negative acknowledgement for these downlink transmissions or may report information devoid of any positive or negative acknowledgement feedback. The UE may be able to determine the number of missed downlink transmissions based on the indication and/or other information (e.g. the location of a PUCCH transmission and the type of codebook used, such as Type-1).

In an example, the locations of cancelled uplink transmission(s) (e.g. PUCCH/PUSCH) carrying HARQ-ACKs may be indicated as a "negative" Ki value. Said differently, an indication may be used in a manner similar to that of Ki, but for indicating how many slots or sub-slots before was the cancelled uplink transmission. Said differently, the negative /Ci value can point back in time in number of slots or sub-slots (rather than forward in time like a conventional Ki value), to the uplink transmission (e.g. PUCCH/PUSCH) carrying HARQ-ACK that was cancelled and is to be retransmitted. The negative Ki value can be defined relatively to the slot or sub-slot of the DCI carrying the retransmission request or ReTx CB trigger. This example is not limited to indicating only one negative /Ci value but multiple negative /Ci values pointing to different cancelled uplink transmissions (e.g. PUCCH/PUSCH) may be indicated. This can also allow the gNB, if it wishes, to select some but not all of cancelled uplink transmissions (e.g. PUCCH/PUSCH) that it wants for retransmission for cases where they are multiple cancelled uplink transmissions (e.g. PUCCH/PUSCH).

It will also be appreciated that in some case the resources location may be indicated using time and/or frequency information. For example, the negative Ki parameter can be viewed as time information identifying a time unit (e.g. slot or sub-slot) in which the uplink resources were found. Additionally or alternatively, frequency information (e.g. a Component Carrier in a Carrier Aggregation operation), may be provided to identify the uplink transmission carrying feedback(s) to be retransmitted. The UE may be configured to identify the corresponding uplink transmission(s) times based on one or more pre determined or configured parameters and retransmit or send feedback information (e.g. negative acknowledgments, or information devoid of specific positive or negative acknowledgement, for missed uplink transmissions) for the identified uplink transmissions. The one or more pre-determined or configured parameters may include for example configure the UE to select the last N slots or sub-slots, with N > 1, wherein this is pre-configured or fixed in the terminal, configured by control signalling (e.g. RRC signalling, system information, etc.) and/or configured by the indication.

An example is shown in Figure 14, DCI#1 and DCI#2 schedule PDSCHffl and PDSCH#2 respectively and their corresponding HARQ-ACKs are scheduled to Low LI priority PUCCHffl and PUCCH#2 respectively. DCI#3 schedules PDSCH#3 and its HARQ-ACK is scheduled to a High LI priority PUCCH#3 which collides with PUCCH#2 resulting in PUCCH#2 being cancelled in favour of PUCCH#3. A ReTx CB trigger is transmitted in DCI#4 and according to this example, it contains a negative Ki = 1 sub-slot (assuming PUCCH#2 was scheduled in sub-slot granularity). This negative Ki value point to sub-slot m+ 6 where PUCCH#2 was cancelled. The UE then retransmits the HARQ-ACK from PUCCH#2 in PUCCH#4. It should be appreciated the negative /Ci can help the UE determine that there is any HARQ-ACK to retransmit. As discussed in the examples above, the UE determines that it has missed DCI#2 and PDSCH#2 associated with PUCCH#2 (identified with the negative Ki value) and therefore can send a negative acknowledgement for this one. As mentioned above, more than one negative value may be included and if an additional negative Ki value of Ki=4 (which is equivalent to indicating Ki=-4), the UE can transmit A1 and N2, where A1 can be positive or negative and N2 will be negative. The use of the negative Ki value also has the benefit of allowing the terminal to order the acknowledgement feedbacks to facilitate identification at the base station. This may for example be in a sequential order (from oldest to newest, e.g. A1,N2), in a reverse order (from newest to oldest, e.g. N2, Al) or in the order of the indicated negative KI values in the retransmission request. As long as both the terminal and base station agree on the same convention for ordering the feedbacks, the base station should be able to identify which feedback corresponds to which downlink transmission.

It will be appreciated, and as mentioned above, that technique provided herein may be combined in any suitable manner, combining two or more of these techniques for example. For example, the example indicating number of cancelled HARQ-ACK Codebooks can combine with the negative /Ci indication to tell the UE which HARQ-ACK Codebook to retransmits.

Additionally or alternatively, the cancelled HARQ-ACK to be retransmitted are identified using a retransmission time window. This recognizes that HARQ-ACKs have been cancelled a long time ago may no longer be worth retransmitting. For example, the gNB may have already retransmitted the PDSCHs associated with those HARQ-ACKs or the original downlink transmission has already failed the latency requirement or would fail if it will have to be retransmitted using these techniques. Again, this retransmission window may be combined with other techniques discussed herein, such as an indication of one or more of a codebook, number of retransmissions, a location of resources etc.

In an implementation, the retransmission time window reference point is the DCI triggering the ReTx CB. An example is shown in Figure 15, where DCI#1, DCI#2, DCI#3 and DCI#4 schedules PDSCHffl, PDSCH#2, PDSCH#3 and PDSCH#4 respectively. PUCCHffl carries HARQ-ACK for PDSCHffl but it is cancelled (in this case by UL Cl to allow for a higher LI priority transmission, PUSCHffl). PUCCH#2 carriers HARQ-ACKs for PDSCH#2 and PDSCH#3 but it is also cancelled (in that case, due to collision with a Higher LI priority transmission, PUCCH#3). The gNB triggers a ReTx CB in DCI#5 and in this example the Retransmission Time Window is 2 slots. It will be appreciated that both the value and measure of the window can vary, for example the time window may be measured in other time units, e.g. symbols, sub-slots, etc. and may be longer or shorter than in this particular illustrative example. The UE will thus only consider cancelled PUCCH within slot n+2 and n+ 3, i.e. the two slots prior to the slot where DCI#5 is transmitted. Since only the cancelled PUCCH#2 falls within the retransmission time window, the UE retransmit the associated HARQ-ACKs for PDSCH#2 and PDSCH#3 which are labelled as Ai and A3, in PUCCH#4, but not the feedback for PUCCHffl.

The retransmission time window may be fixed (e.g. according to a convention or standard between the UE and gNB) or may be configured, e.g. using one or more of: RRC signalling, system information, etc.. In another example, the retransmission time window configuration may be indicated in the retransmission request (referred to as "ReTx CB trigger" herein), e.g. indicated in the DCI in the illustrative examples provided herein. This indication can be the duration of the retransmission time window or an index to a table containing different RRC configured retransmission time windows or an index on a preconfigured table (e.g. a table specified in a standardized specification), etc.

Retransmission Request and Response Format

The retransmission request or ReTx CB may use one or more formats. For example, the retransmission request may or may not schedule a PDSCH, e.g. if it is sent as part of downlink control information such as a DCI which may be also used to schedule a PDSCH. In cases where the gNB schedules a PDSCH using the retransmission request (e.g. with a DCI trigger), the UE may need to send the HARQ-ACK feedback. retransmission request (e.g. ReTx CB Trigger) without PDSCH scheduling

In a first example, the retransmission request (e.g. the DCI) triggering the ReTx CB does not schedule a PDSCH. For example, a DCI is used which schedules only a PUCCH for the retransmission of cancelled HARQ-ACKs. As the skilled reader would have identified, the examples in Figures 9 to 15 are examples illustrating this implementation where only PUCCH is scheduled with the retransmission request. In an example, the retransmitted acknowledgment feedbacks (e.g. HARQ-ACKs) are arranged according to the order of their corresponding cancelled HARQ-ACK Codebooks. An example is shown in Figure 16, where PUCCHffl carries Codebook CBi which contains HARQ-ACKs for PDSCHs with HARQ Process ID (or HARQ Process Number) 12 (not shown in the figure) and 3 (associated with PDSCHffl). PUCCH#2 carries Codebook CB₂ which contains HARQ-ACKs for PDSCH#2 and PDSCH#3 with HARQ Process ID 4 and 7 respectively. PUCCHffl and PUCCH#2 are cancelled due to collision with higher LI priority transmissions. The gNB then transmits DCI#5 to trigger a ReTx CB and as per this example, the HARQ-ACKs are arranged according to the cancellation of their corresponding Codebook starting with the latest cancelled Codebook, i.e. CB₂ first followed by CSi.

Likewise, in one example, they can be ordered starting with the oldest of the cancelled Codebook(s), i.e. CBi followed by CB2, e.g. {H12, H3, H4, H7}.

In another example (or within each CodeBook), the feedbacks (e.g. HARQ-ACKs) are arranged according to their associated acknowledgment process identifier (e.g. HARQ-Process ID) and, optionally and if appropriate, by Carrier (e.g. for Carrier Aggregation operations). In an implementation with Carrier Aggregation operations, the Carrier can firstly be sorted and in each carrier the HARQ-Process ID is arranged in ascending or descending order and is transmitted.

An example is shown Figure 17, which has the same scenario as the example in Figure 16, where a single carrier operation is assume, for illustrative purposes. The retransmission codebook would thus result in arranging the acknowledgment feedbacks according to their HARQ Process ID, i.e. {H3, H4, H₇, Hu} in this particular example. retransmission request (e.g. ReTx CB Trigger) with PDSCH scheduling

In some cases, the retransmission request format may be such that the downlink control information (e.g. DIC) triggering the retransmission request may also schedule one or more downlink (data) transmissions, e.g. PDSCHs. It will also be appreciated that using MIMO, the gNB may also schedule multiple PDSCHs in a single DL Grant.

In one example, the acknowledgment feedback is transmitted using the same ordering rules for both fresh feedback and retransmitted feedback following a retransmission. Viewed from a different perspective, the acknowledgments (HARQ-ACKs) that a retransmitted or not are arranged together according to an order. It will be appreciated that because a PDSCH is scheduled with the retransmission request, at least one acknowledgment feedback will be due to be transmitted by the UE.

• In an example, the HARQ-ACKs are scheduled according to their HARQ Process ID (or HARQ Process Number) regardless if they are retransmitted HARQ-ACKs or not.

In another example, the HARQ-ACKs are scheduled according to the cancellation of their corresponding HARQ-ACK Codebook regardless if they are retransmitted HARQ-ACKs or not. In another example, non-retransmitted HARQ-ACKs may be arranged or ordered separately from acknowledgments which are not retransmitted, for example acknowledgments which are being scheduled for the first time.

In an example, the acknowledgments HARQ-ACK(s) associated with PDSCH(s) scheduled by or with the retransmission request, e.g. DCI triggering the ReTx CB, is (are) concatenated with retransmitted HARQ- ACKs. This is illustrated in Figure 18, where PUCCHffl and PUCCH#2 are cancelled due to collisions with higher LI priority transmissions. DCI#5 triggers a ReTx CB and also schedules PDSCH#5 where its HARQ- ACK is transmitted in PUCCH#4. In this example, the retransmitted HARQ-ACKs are arranged according to their HARQ Process ID as per a previous example but the HARQ-ACK for PDSCH#5 is concatenated at the front of the ReTx CB. Likewise, in other implementations, the acknowledgment feedback (e.g. HARQ-ACK) for PDSCH#5 can be appended at the end of the ReTx CB.

The same technique may be used when the acknowledgment feedback(s) for the non-retransmitted acknowledgment feedbacks (the acknowledgment feedbacks which are scheduled for the first time) include two or more acknowledgment feedbacks. Said differently, in some examples, all non- retransmitted HARQ-ACKs can be concatenated with the retransmitted HARQ-ACKs. The non- retransmitted HARQ-ACKs can be associated with PDSCH scheduled by or with the retransmission request (e.g. trigger DCI) or by other Downlink Grants.

An example is provided in Figure 19, where PUCCHffl and PUCCH#2 are cancelled due to collisions with higher LI priority transmissions PUSCHffl and PUSCH#2 and are cancelled by UL CL DCI#4 schedules PDSCH#4 where its HARQ-ACK is transmitted in PUCCH#3. DCI#5 triggers a ReTx CB and also schedules PDSCH#5 where the ReTx CB and the HARQ-ACK for PDSCH#5 are transmitted in PUCCH#3. Hence PUCCH#3 contains HARQ-ACK for PDSCH#4 and PDSCH#5 with HARQ Process ID 8 and 10 respectively and the retransmitted HARQ-ACKs with HARQ Process IDs 12, 3, 4 and 7 respectively. In this case the retransmitted HARQ-ACKs are arranged according to their HARQ Process IDs as discussed above, although in other arrangements, the codebook and/or any other suitable ordering technique may be used. The non-retransmitted HARQ-ACKs are concatenated at the front of the retransmitted HARQ-ACKs. Therefore, resulting HARQ-ACK arrangement carried by PUCCH#3 firstly contains {Hg, Hw} followed by {H₃, H , H₇, H 12}. Again, it will be appreciated that the concatenation of the non-retransmitted HARQ-ACKs can be appended at the back of the retransmitted HARQ-ACKs.

NULL Feedback

In some cases, the UE is not be in a position to conclusively identify which acknowledgment feedback(s) or HARQ-ACKs may need to be retransmitted and/or the gNB indication associated with the retransmission request may not enable the UE to determine the number of HARQ-ACK retransmissions.

In such cases, the UE can indicate a "NULL" in the feedback, which may for example be a special bit string in the ReTx CB.

This is illustrated in Figure 20, which corresponds to the example of Figure 13. Here the gNB indicates to the UE to retransmit the HARQ-ACKs in PUCCH#2. If for example the gNB does not implement the features discussed regarding the indication of the number of cancelled HARQ-ACK to be retransmitted, the UE may be unable to determine the number of acknowledgment feedback(s) expected. The UE is unaware of the existence of PUCCH#2, and it may be unable to determine the number of HARQ-ACKs contained in PUCCH#2 as DCI#2 may schedule two PDSCHs using MIMO and as the UE might have missed another additional DCI / PDSCH / PUCCH scheduling. In this example, the UE may then send a "NULL" feedback in the retransmission reply (e.g. ReTx CB) to the gNB. The gNB may then be able to determine that the NULL feedback should be treated as negative feedback for all the requested retransmissions.

In another example, the NULL or NULL-like feedback may be provided in the form of a known set of bits. For example, the UE may send an all "NACKS" for a pre-determined number of HARQ-ACKs or a single "NACK" regardless the number of HARQ-ACKs the UE thinks it needs to retransmit.

Transmission of the HARQ-ACK Indication

In an example the said (HARQ-ACK) indication is carried by in a DCI field or in another downlink control information field. The field may be a newly introduced field or may reuse an existing DCI field.

For example, the following are some possible (and non-exhaustive options):

• For negative K1 value, the existing " PDSCH-to-HARQ_feedback timing indicator" can be reused where the UE re-interpret it as a negative value. A separate lookup table associating the index to the Ki values can be RRC configured.

• The MCS field can be reused to indicate the number of HARQ-ACK NHARQ-ACK ^O be retransmitted. Here it is assumed that the DCI triggering the ReTx CB does not schedule a PDSCH.

Accordingly, the techniques provided herein can help reduce the risk of having discrepancies in the acknowledgment feedback reporting, between the communications device and the base station, thereby reducing the risk of having discrepancies causing inefficiencies.

Figure 21 illustrates an example method in accordance with the present disclosure. In this method, a network node determines that one or more acknowledgement feedbacks have not been received from a communications device. The network node may for example be a base station, a relay, a TRP, a RRH, etc..

The network node transmits to the communications device, a retransmission request and an indication indicating the one or more acknowledgement feedbacks to be retransmitted. In some case, the indication may be included in the retransmission request.

Upon receiving the retransmission request and using the indication, the communications device determines whether or not it has received a first downlink grant for a first downlink transmission corresponding to first acknowledgement feedback of the one or more first acknowledgement feedback.

The communications device then reports feedback information to the network node and if the first downlink transmission was not received, the feedback information can indicate that it was not received. Reporting that the first downlink grant and/or first downlink transmission was not received may be done using a negative acknowledgment for the first downlink transmission or a blanket negative acknowledgement (e.g. "NULL" response) devoid of any specific feedback, indicating all negative acknowledgements.

For example, the communications device may transmit a message comprising the one or more acknowledgement feedbacks, the one or more acknowledgement feedbacks comprising a negative acknowledgement feedback associated with the first downlink transmission and, optionally, at least one additional acknowledgement feedback which may for example be either positive or negative.

As mentioned above, the communications device may, upon determining that it is unable to identify the one or more acknowledgement feedbacks to be retransmitted, , the terminal may transmit to the network node a message devoid of acknowledgement feedback, including for example a "NULL" indication instead, thereby providing a negative acknowledgment for the first downlink transmission, and any other downlink transmission for which a retransmission of acknowledgment feedback has been possibly requested.

The indication may comprise one or more of an index of a downlink transmission for which an acknowledgment feedback is requested to be retransmitted; a Downlink Assignment Index (DAI) identifying the index of the last downlink transmission from the network node for which acknowledgement feedback has not yet been received; a number of outstanding acknowledgement feedbacks corresponding to the one or more acknowledgement feedbacks; a number of cancelled uplink transmissions, the cancelled uplink transmissions being associated with carrying the one or more acknowledgement feedbacks; a number of cancelled groups of acknowledgement feedbacks; a number of cancelled groups of acknowledgement feedbacks wherein the groups corresponds to groups of acknowledgement feedbacks to be multiplexed in an uplink transmission and/or corresponds to a HARQ- ACK CodeBook; and a negative time index identifying a time unit in which the one or more acknowledgement feedbacks were scheduled. The time unit may for example be measured in slot, sub slot, OFDM symbols, etc.

In some cases, determining that the one or more acknowledgement feedbacks have not been received may include determining that the resources for the one or more acknowledgement feedbacks collided in time with further resources for at least one further acknowledgment feedback. For example, the at least one further acknowledgment feedback may be associated with a higher priority than the priority of the one or more acknowledgement feedbacks.

As previously discussed, in some cases, the retransmission request may comprise the indication and in some cases it may comprise some of the indication or no part of the indication. For example, in some cases the retransmission request can include a number of acknowledgement feedbacks to be transmitted (which can be seen as a first portion of the indication) while a downlink transmission index (e.g. DAI) is sent in a downlink grant for a further downlink transmissions (e.g. a high priority transmission as mentioned above). In such a case, the indication comprises a first portion sent with the re-transmission request and a second portion sent separately from the retransmission request. The skilled person will appreciate that in both cases, the indication (and each portion thereof) will be associated with the retransmission request. Additionally or alternatively, the indication may be transmitted at least in part in a downlink grant for a high priority uplink transmission (e.g. uplink control transmission such as a PUCCH transmission), which may be associated with a downlink transmission, the high priority uplink transmission being of a higher priority than the priority of the one or more uplink transmissions corresponding to the one or more acknowledgement feedbacks.

In some examples, reporting feedback information may comprise identifying, based on the indication, at least one uplink acknowledgment transmission falling within a time window prior to the retransmission request, the least one uplink acknowledgment transmission being for transmitting at least one acknowledgment feedback, wherein the reported feedback information comprises the at least one acknowledgment feedback. In other words, the communications device can determine which acknowledgement feedback or feedbacks to report on based on a time window and retransmit or report only for the acknowledgement feedback(s) falling within the time window. This may also be used in combination with other techniques, such as an identification of a number of acknowledgement feedback, codebook (group of acknowledgment feedbacks), etc.

For example, if the communications device determines that it has not received the first downlink grant and if the at least one acknowledgment feedback comprises the first acknowledgement feedback, the at least one acknowledgment feedback may comprise a negative acknowledgement feedback associated with the first downlink transmission.

For example, if the terminal identifies a second uplink acknowledgment transmission falling outside of the time window prior to the retransmission request, the second uplink acknowledgment transmission being for transmitting a second acknowledgment feedback; the communications device can disregard the second acknowledgment feedback when transmitting the at least one acknowledgment feedback. For example, if the communications device identifies a second acknowledgement feedback which falls outside of the time window, the communications device will not include this second acknowledgement feedback in the feedback information, as this will be deemed too old to be reported. It will be appreciated that this applied whether the second acknowledgement feedback was previously identified and transmitted or was missed and thus not previously transmitted.

In some cases, the retransmission request comprises a second downlink grant for a second downlink transmission and for a corresponding uplink transmission for the second acknowledgement feedback in respect of the second downlink transmission. In further examples, the communications device reporting to the network node that the first downlink transmission was not received may then comprise the communications device transmitting a negative acknowledgment for the first downlink transmission using the corresponding uplink transmission.

Depending on the perspective, the control information or control signal (e.g. DCI) associated with a downlink transmissions (e.g. PDSCFI) may be considered as being part of the transmission or as being a separate transmission associated with the transmission. Either way, the control information is associated with a transmission from a network node to a terminal device. It will also be appreciated that in the present disclosure, the teachings and techniques applied to DCIs and/or PDSCFIs can be equally applied to downlink control information or downlink grant information and to downlink transmissions such as downlink data transmissions. Likewise, teachings and techniques applied to PUCCH and PUSCH can be equally applied to uplink control transmissions or uplink acknowledgement feedback transmissions and uplink transmissions such as uplink data transmissions.

The term resources or resource can refer to any suitable set of time and frequency resources to be used to transmit signals on the wireless interface. This may be measured in some cases based on a resource blocks, slots, frames or any other resource unit deemed appropriate.

While reference has sometimes been made to particular sets of standards, for example different release versions ("Release 15", "Release 16", etc.), it will be appreciated that this is done for illustrative purposes only and the teachings and techniques of the present invention are not limited to these particular systems but rather these systems are used to illustrates limitations that can be found in some systems and how these limitations may be addressed.

Additionally, the method steps discussed herein may be carried out in any suitable order. For example, steps may be carried out in an order which differs from an order used in the examples discussed above or from an indicative order used anywhere else for listing steps (e.g. in the claims), whenever possible or appropriate. Thus, in some cases, some steps may be carried out in a different order, or simultaneously or in the same order. So long as an order for carrying any of the steps of any method discussed herein is technically feasible, it is explicitly encompassed within the present disclosure.

As used herein, transmitting information or a message to an element may involve sending one or more messages to the element and may involve sending part of the information separately from the rest of the information. The number of "messages" involved may also vary depending on the layer or granularity considered. For example transmitting a message may involve using several resource elements in an LTE or NR environment such that several signals at a lower layer correspond to a single message at a higher layer. Also, transmissions from one node to another may relate to the transmission of any one or more of user data, system information, control signalling and any other type of information to be transmitted.

Also, whenever an aspect is disclosed in respect of an apparatus or system, the teachings are also disclosed for the corresponding method and for the corresponding computer program. Likewise, whenever an aspect is disclosed in respect of a method, the teachings are also disclosed for any suitable corresponding apparatus or system. Additionally, it is also hereby explicitly disclosed that for any teachings relating to a method or a system where it has not been clearly specified which element or elements are configured to carry out a function or a step, any suitable element or elements that can carry out the function can be configured to carry out this function or step. For example, any one or more of a terminal device or network node may be configured accordingly if appropriate, so long as it is technically feasible and not explicitly excluded.

Whenever the expressions "greater than" or "smaller than" or equivalent are used herein, it is intended that they discloses both alternatives "and equal to" and "and not equal to" unless one alternative is expressly excluded. It will be appreciated that while the present disclosure has in some respects focused on implementations in a 5G or NR network as such a network is expected to provide the primary use case at present, the same teachings and principles can also be applied to other wireless telecommunications systems. Thus, even though the terminology used herein is generally the same or similar to that of the 5G (or LTE) standards, the teachings are not limited to the present versions 5G (or LTE) and could apply equally to any appropriate arrangement not based on 5G / LTE, for example any arrangement possibly compliant with any future version of an LTE, 5G or other standards - defined by the 3GPP standardisation groups or by other groups. Accordingly, the teaching provided herein using 3GPP, LTE and/or 5G / NR terminology can be equally applied to other systems with reference to the corresponding functions. For example, references to HARQ-ACK or DCI can be more generally understood as references to acknowledgements (positive or negative) or control information relating to the downlink.

It is noteworthy that where a "predetermined" element is mentioned, it will be appreciated that this can include for example a configurable element, wherein the configuration can be done by any combination of a manual configuration by a user or administrator or a transmitted communication, for example from the network or from a service provider (e.g. a device manufacturer, an OS provider, etc.).

Techniques discussed herein can be implemented using a computer program product, comprising for example computer-readable instructions which can be executed by a computer, for carrying a method according to the present disclosure. Such a computer readable medium may be a non-transitory computer-readable storage medium with an executable program stored thereon, wherein the program instructs a microprocessor to perform said method. Additionally, or alternatively, the techniques discussed herein may be realised at least in part by a computer readable communication medium that carries or communicates code in the form of instructions or data structures and that can be accessed, read, and/or executed by a computer.

In other words, any suitable computer readable medium may be used, which comprises instructions and which can for example be a transitory medium, such as a communication medium, or a non-transitory medium, such as a storage medium. Accordingly, a computer program product may be a non-transitory computer program product.

Further particular and preferred aspects of the present invention are set out in the accompanying independent and dependent claims. It will be appreciated that features of the dependent claims may be combined with features of the independent claims in combinations other than those explicitly set out in the claims.

Thus, the foregoing discussion discloses and describes merely illustrative examples of the present disclosure. As will be understood by those skilled in the art, the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting of the scope of the invention, as well as other claims. The disclosure, including any readily discernible variants of the teachings herein, define, in part, the scope of the foregoing claim terminology such that no inventive subject matter is dedicated to the public. Respective features of the present disclosure are defined by the following numbered clauses:

Clause 1. A method for managing acknowledgments in a telecommunications network, the telecommunications network comprising a network node arranged to communicate with a communications device via a wireless interface, the method comprising: determining, by the network node, that one or more acknowledgement feedbacks have not been received from the communications device; transmitting, by the network node and to the communications device, a retransmission request; transmitting, by the network node and to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, the communications device determining whether it has received a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more acknowledgement feedbacks to be retransmitted; and the communications device reporting feedback information to the network node, the feedback information being identified based on the indication, wherein, if the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received. Clause 2. The method of Clause 1 wherein the communications device reporting feedback information to the network node wherein feedback information notifies the network node that the first downlink transmission was not received comprises: transmitting, by the communications device, a message comprising the one or more acknowledgement feedbacks, the one or more acknowledgement feedbacks comprising a negative acknowledgement feedback associated with the first downlink transmission.

Clause 3. The method of any preceding Clause wherein, when the communications device is unable to identify the one or more acknowledgement feedbacks to be retransmitted, the reported feedback information is devoid of acknowledgement feedback.

Clause 4. The method of any preceding Clause , wherein the indication comprises one or more of: an index of a downlink transmission for which an acknowledgment feedback is requested to be retransmitted; a Downlink Assignment Index (DAI) identifying the index of the last downlink transmission from the network node for which acknowledgement feedback has not yet been received; a number of outstanding acknowledgement feedbacks corresponding to the one or more acknowledgement feedbacks; a number of cancelled uplink transmissions, the cancelled uplink transmissions being associated with carrying the one or more acknowledgement feedbacks; a number of cancelled groups of acknowledgement feedbacks; a number of cancelled groups of acknowledgement feedbacks wherein the groups corresponds to groups of acknowledgement feedbacks to be multiplexed in an uplink transmission and/or corresponds to a HARQ-ACK CodeBook; and a negative time index identifying a time unit in which the one or more acknowledgement feedbacks were scheduled. Clause 5. The method of any preceding Clause , wherein determining that the one or more acknowledgement feedbacks have not been received comprises determining that the resources for the one or more acknowledgement feedbacks collided in time with further resources for at least one further acknowledgment feedback.

Clause 6. The method of Clause 5, wherein the at least one further acknowledgment feedback are is associated with an uplink transmission of a higher priority than the priority of the one or more uplink transmissions associated with the one or more acknowledgement feedbacks.

Clause 7. The method of any preceding Clause wherein the indication is transmitted at least in part in the retransmission request.

Clause 8. The method of any preceding Clause wherein the indication is transmitted at least in part in a downlink grant for a high priority uplink transmission carrying acknowledgement feedbacks associated with a downlink transmission, the high priority uplink transmission being of a higher priority than the priority of the one or more uplink transmissions corresponding to the one or more acknowledgement feedbacks.

Clause 9. The method of any preceding Clause , wherein reporting feedback information comprises: identifying, based on the indication, at least one uplink acknowledgment transmission falling within a time window prior to the retransmission request, the least one uplink acknowledgment transmission being for transmitting at least one acknowledgment feedback, wherein the reported feedback information comprises the at least one acknowledgment feedback. Clause 10. The method of Clause 9, wherein, if the communications device determines that it has not received the first downlink grant and if the at least one acknowledgment feedback comprises the first acknowledgement feedback, the at least one acknowledgment feedback comprises a negative acknowledgement feedback for the first acknowledgement feedback.

Clause 11. The method of Clause 9 or 10 wherein the communications device reporting that the first downlink transmission was not received further comprises: identifying, based on the indication, a second uplink acknowledgment transmission falling outside of the time window prior to the retransmission request, the second uplink acknowledgment transmission being for transmitting a second acknowledgment feedback; and disregarding the second acknowledgment feedback when transmitting the at least one acknowledgment feedback.

Clause 12. The method of any preceding Clause , wherein wherein the retransmission request is associated with a second downlink grant for a second downlink transmission and for a corresponding uplink transmission for the second acknowledgement feedback in respect of the second downlink transmission; and wherein the communications device reporting feedback information to the network node comprises the communications device reporting feedback information using the corresponding uplink transmission. Clause 13. A system for acknowledgement retransmission in a telecommunications network, the telecommunications network comprising a network node arranged to communicate with a communications device via a wireless interface, the system comprising the network node and the communications device, wherein: the network node is configured to: determine that one or more acknowledgement feedbacks have not been received from the communications device; transmit, to the communications device, a retransmission request; transmit, to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; the communications device is configured to: determine, upon receiving the retransmission request and using the indication, whether it has received a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more acknowledgement feedbacks to be retransmitted; and report feedback information to the network node, the feedback information being identified based on the indication, wherein, if the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received. Clause 14. A method of operating a network node in a telecommunications network, the network node being configured to communicate with a communications device of the telecommunications network via a wireless interface, the method comprising: determining that one or more acknowledgement feedbacks have not been received from the communications device; transmitting, to the communications device, a retransmission request; transmitting, to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; and receiving, from the communications device and in response to the retransmission request, a report comprising feedback information.

Clause 15. The method of Clause 14 wherein the feedback information notifies the network node that a first downlink transmission was not received, the first downlink transmission being associated with a first acknowledgement feedback of one or more acknowledgement feedbacks and the first acknowledgement feedback comprising a negative acknowledgement feedback associated with the first downlink transmission.

Clause 16. The method of Clause 14 or 15 wherein, the reported feedback information is devoid of acknowledgement feedback, thereby indicating that the communications device was unable to identify the one or more acknowledgement feedbacks to be retransmitted,.

Clause 17. The method of any one of Clauses 14 to 16, wherein the indication comprises one or more of: an index of a downlink transmission for which an acknowledgment feedback is requested to be retransmitted; a Downlink Assignment Index (DAI) identifying the index of the last downlink transmission from the network node for which acknowledgement feedback has not yet been received; a number of outstanding acknowledgement feedbacks corresponding to the one or more acknowledgement feedbacks; a number of cancelled uplink transmissions, the cancelled uplink transmissions being associated with carrying the one or more acknowledgement feedbacks; a number of cancelled groups of acknowledgement feedbacks; a number of cancelled groups of acknowledgement feedbacks wherein the groups corresponds to groups of acknowledgement feedbacks to be multiplexed in an uplink transmission and/or corresponds to a HARQ-ACK CodeBook; and a negative time index identifying a time unit in which the one or more acknowledgement feedbacks were scheduled.

Clause 18. The method of any one of Clauses 14 to 17, wherein determining that the one or more acknowledgement feedbacks have not been received comprises determining that the resources for the one or more acknowledgement feedbacks collided in time with further resources for at least one further acknowledgment feedback.

Clause 19. The method of Clause 18, wherein the at least one further acknowledgment feedback is associated with an uplink transmission of a higher priority than the priority of the one or more uplink transmissions associated with the one or more acknowledgement feedbacks.

Clause 20. The method of any one of Clauses 14 to 19, wherein the indication is transmitted at least in part in the retransmission request.

Clause 21. The method of any one of Clauses 14 to 20, wherein the indication is transmitted at least in part in a downlink grant for a high priority uplink transmission carrying acknowledgement feedbacks associated with a downlink transmission, the high priority uplink transmission being of a higher priority than the priority of the one or more uplink transmissions corresponding to the one or more acknowledgement feedbacks.

Clause 22. The method of any one of Clauses 14 to 21, wherein reporting feedback information comprises at least one acknowledgment feedback, the at least one acknowledgment feedback being scheduled to be originally transmitted in at least one uplink acknowledgment transmission falling within a time window prior to the retransmission request.

Clause 23. The method of any one of Clauses 14 to 22, wherein wherein the retransmission request is associated with a second downlink grant for a second downlink transmission and for a corresponding uplink transmission for the second acknowledgement feedback in respect of the second downlink transmission; and wherein receiving the feedback information comprises receiving the feedback information using the corresponding uplink transmission.

Clause 24. A network node for use in a telecommunications network, the network node comprising a transceiver element and controller configured to operate together to provide a wireless interface and to communicate with a communications device of the telecommunications network via the wireless interface, the transceiver element and controller being further configured to: determine that one or more acknowledgement feedbacks have not been received from the communications device; transmit, to the communications device, a retransmission request; transmit, to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; and receive, from the communications device and in response to the retransmission request, a report comprising feedback information. Clause 25. The network node of Clause 24 configured to implement the method of any one of Clauses 14 to 23.

Clause 26. Circuitry for a network node for use in a mobile telecommunications network, the network comprising a communications device and the network node, the network node being configured to provide a wireless interface to the communications device, wherein the circuitry comprises a controller element and a transceiver element configured to operate together to communicate with the communications device via the wireless interface and wherein the controller element and the transceiver element are further configured to operate together to implement the method any one of Clauses 14 to 23.

Clause 27. A method of operating a communications device in a telecommunications network, the telecommunications network comprising a network node arranged to communicate with the communications device via a wireless interface, the method comprising: receiving, from the network node, a retransmission request; receiving, from the network node, an indication indicating one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, determining whether a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback one of the one or more first acknowledgement feedback has been received; and reporting feedback information to the network node, wherein, if the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received. Clause 28. The method of Clause 27 wherein reporting feedback information to the network node, when the feedback information notifies the network node that the first downlink transmission was not received, comprises: transmitting a message comprising the one or more acknowledgement feedbacks, the one or more acknowledgement feedbacks comprising a negative acknowledgement feedback associated with the first downlink transmission.

Clause 29. The method of Clause 27 or 28wherein, when the communications device is unable to identify the one or more acknowledgement feedbacks to be retransmitted, the reported feedback information is devoid of acknowledgement feedback.

Clause 30. The method of any one of Clauses 27 to 29, wherein the indication comprises one or more of: an index of a downlink transmission for which an acknowledgment feedback is requested to be retransmitted; a Downlink Assignment Index (DAI) identifying the index of the last downlink transmission from the network node for which acknowledgement feedback has not yet been received; a number of outstanding acknowledgement feedbacks corresponding to the one or more acknowledgement feedbacks; a number of cancelled uplink transmissions, the cancelled uplink transmissions being associated with carrying the one or more acknowledgement feedbacks; a number of cancelled groups of acknowledgement feedbacks; a number of cancelled groups of acknowledgement feedbacks wherein the groups corresponds to groups of acknowledgement feedbacks to be multiplexed in an uplink transmission and/or corresponds to a HARQ-ACK CodeBook; and a negative time index identifying a time unit in which the one or more acknowledgement feedbacks were scheduled.

Clause 31. The method of any one of Clauses 27 to 30 wherein the indication is received at least in part in the retransmission request.

Clause 32. The method of any one of Clauses 27 to 31, wherein the indication is received at least in part in a downlink grant for a high priority uplink transmission carrying acknowledgement feedbacks associated with a downlink transmission, the high priority uplink transmission being of a higher priority than the priority of one or more uplink transmissions corresponding to the one or more acknowledgement feedbacks.

Clause 33. The method of any one of Clauses 27 to 32, wherein reporting feedback information comprises: identifying, based on the indication, at least one uplink acknowledgment transmission falling within a time window prior to the retransmission request, the least one uplink acknowledgment transmission being for transmitting at least one acknowledgment feedback, wherein the reported feedback information comprises the at least one acknowledgment feedback. Clause 34. The method of Clause 33, wherein, if the communications device determines that it has not received the first downlink grant and if the at least one acknowledgment feedback comprises the first acknowledgement feedback, the at least one acknowledgment feedback comprises a negative acknowledgement feedback for the first acknowledgement feedback.

Clause 35. The method of Clause 33 or 34 wherein reporting that the first downlink transmission was not received further comprises: identifying, based on the indication, a second uplink acknowledgment transmission falling outside of the time window prior to the retransmission request, the second uplink acknowledgment transmission being for transmitting a second acknowledgment feedback; and disregarding the second acknowledgment feedback when transmitting the at least one acknowledgment feedback.

Clause 36. The method of any one of Clauses 27 to 35, wherein wherein the retransmission request is associated with a second downlink grant for a second downlink transmission and for a corresponding uplink transmission for the second acknowledgement feedback in respect of the second downlink transmission; and wherein reporting feedback information to the network node comprises reporting feedback information using the corresponding uplink transmission.

Clause 37. A communications device for use in a telecommunications network, the communications device comprising a transceiver element and controller configured to operate together to communicate with a network node of the telecommunications network via a wireless interface provided by the network node, the transceiver element and controller being further configured to: receive, from the network node, a retransmission request; receive, from the network node, an indication indicating one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, determine whether a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more first acknowledgement feedback has been received; and report feedback information to the network node, wherein if the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received. Clause 38. The communications device of Clause 37 wherein the communications device is further configured to implement the method of any one of Clauses 27 to 36.

Clause 39. Circuitry for a communications device for use in a mobile telecommunications network, the network comprising the communications device and a network node configured to provide a wireless interface to the communications device, wherein the circuitry comprises a controller element and a transceiver element configured to operate together to communicate with the network node via the wireless interface and wherein the controller element and the transceiver element are further configured to operate together to implement the method any one of Clauses 27 to 36.

Clause 40. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of any one of Clauses 1 to 12, 14 to 23 and 27 to 36.

REFERENCES

[1] 3GPP document RP-160671, "New SID Proposal: Study on New Radio Access Technology," NTT DOCOMO, RAN#71, Gothenburg, Sweden, 7 to 10 March 2016

[2] 3GPP document RP-172834, "Work Item on New Radio (NR) Access Technology," NTT DOCOMO, RAN#78, Lisbon, Portugal, 18 to 21 December 2017

[3] 3GPP document RP-182089, "New SID on Physical Layer Enhancements for NR Ultra-Reliable and Low Latency Communication (URLLC)," Huawei, HiSilicon, Nokia, Nokia Shanghai Bell, RAN#81, Gold Coast, Australia, 10 to 13 September 2018

[4] 3GPP document RP-190654, "New WID: Physical layer enhancements for NR ultra-reliable and low latency communication (URLLC)," Huawei, HiSilicon, RAN#83, Shenzhen, China, 18 to 21 March 2019

[5] TR38.913, "Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14)", vl4.3.0

[6] RP-190726, "Physical layer enhancements for NR ultra-reliable and low latency communication (URLLC)," Huawei, HiSilicon, RAN#83

[7] RP-193233, "Enhanced Industrial Internet of Things (loT) and URLLC support," Nokia, Nokia Shanghai Bell, RAN#86

[8] RP-191575, "NR-based Access to Unlicensed Spectrum," Qualcomm, RAN#84

[9] Holma H. and Toskala A, "LTE for UMTS OFDMA and SC-FDMA based radio access", John Wiley and Sons, 2009

[10] EP 20187799.0 filed 24 July 2020 entitled "Mobile nodes, network nodes, circuitry, systems and methods" [11] Rl-2105160, "Retransmission of dropped HARQ-ACK for URLLC," Sony, RANl#105e

[12] EP 20189053.0 filed 31 Jul 2020 and entitled "Methods, communications devices, and infrastructure equipment"

Claims

Claims

1. A method for managing acknowledgments in a telecommunications network, the telecommunications network comprising a network node arranged to communicate with a communications device via a wireless interface, the method comprising: determining, by the network node, that one or more acknowledgement feedbacks have not been received from the communications device; transmitting, by the network node and to the communications device, a retransmission request; transmitting, by the network node and to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, the communications device determining whether it has received a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more acknowledgement feedbacks to be retransmitted; and the communications device reporting feedback information to the network node, the feedback information being identified based on the indication, wherein, if the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received.

2. The method of claim 1 wherein the communications device reporting feedback information to the network node wherein feedback information notifies the network node that the first downlink transmission was not received comprises: transmitting, by the communications device, a message comprising the one or more acknowledgement feedbacks, the one or more acknowledgement feedbacks comprising a negative acknowledgement feedback associated with the first downlink transmission.

3. The method of claim 1 wherein, when the communications device is unable to identify the one or more acknowledgement feedbacks to be retransmitted, the reported feedback information is devoid of acknowledgement feedback.

4. The method of claim 1, wherein the indication comprises one or more of: an index of a downlink transmission for which an acknowledgment feedback is requested to be retransmitted; a Downlink Assignment Index (DAI) identifying the index of the last downlink transmission from the network node for which acknowledgement feedback has not yet been received; a number of outstanding acknowledgement feedbacks corresponding to the one or more acknowledgement feedbacks; a number of cancelled uplink transmissions, the cancelled uplink transmissions being associated with carrying the one or more acknowledgement feedbacks; a number of cancelled groups of acknowledgement feedbacks; a number of cancelled groups of acknowledgement feedbacks wherein the groups corresponds to groups of acknowledgement feedbacks to be multiplexed in an uplink transmission and/or corresponds to a HARQ-ACK CodeBook; and a negative time index identifying a time unit in which the one or more acknowledgement feedbacks were scheduled.

5. The method of claim 1, wherein determining that the one or more acknowledgement feedbacks have not been received comprises determining that the resources for the one or more acknowledgement feedbacks collided in time with further resources for at least one further acknowledgment feedback.

6. The method of claim 5, wherein the at least one further acknowledgment feedback is associated with an uplink transmission of a higher priority than the priority of the one or more uplink transmissions associated with the one or more acknowledgement feedbacks.

7. The method of claim 1 wherein the indication is transmitted at least in part in the retransmission request.

8. The method of claim 1 wherein the indication is transmitted at least in part in a downlink grant for a high priority uplink transmission carrying acknowledgement feedbacks associated with a downlink transmission, the high priority uplink transmission being of a higher priority than the priority of the one or more uplink transmissions corresponding to the one or more acknowledgement feedbacks.

9. The method of claim 1, wherein reporting feedback information comprises: identifying, based on the indication, at least one uplink acknowledgment transmission falling within a time window prior to the retransmission request, the least one uplink acknowledgment transmission being for transmitting at least one acknowledgment feedback, wherein the reported feedback information comprises the at least one acknowledgment feedback.

10. The method of claim 9, wherein, if the communications device determines that it has not received the first downlink grant and if the at least one acknowledgment feedback comprises the first acknowledgement feedback, the at least one acknowledgment feedback comprises a negative acknowledgement feedback for the first acknowledgement feedback.

11. The method of claim 1, wherein wherein the retransmission request is associated with a second downlink grant for a second downlink transmission and for a corresponding uplink transmission for the second acknowledgement feedback in respect of the second downlink transmission; and wherein the communications device reporting feedback information to the network node comprises the communications device reporting feedback information using the corresponding uplink transmission.

12. A system for acknowledgement retransmission in a telecommunications network, the telecommunications network comprising a network node arranged to communicate with a communications device via a wireless interface, the system comprising the network node and the communications device, wherein: the network node is configured to: determine that one or more acknowledgement feedbacks have not been received from the communications device; transmit, to the communications device, a retransmission request; transmit, to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; the communications device is configured to: determine, upon receiving the retransmission request and using the indication, whether it has received a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more acknowledgement feedbacks to be retransmitted; and report feedback information to the network node, the feedback information being identified based on the indication, wherein, if the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received.

13. A method of operating a network node in a telecommunications network, the network node being configured to communicate with a communications device of the telecommunications network via a wireless interface, the method comprising: determining that one or more acknowledgement feedbacks have not been received from the communications device; transmitting, to the communications device, a retransmission request; transmitting, to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; and receiving, from the communications device and in response to the retransmission request, a report comprising feedback information.

14. A network node for use in a telecommunications network, the network node comprising a transceiver element and controller configured to operate together to provide a wireless interface and to communicate with a communications device of the telecommunications network via the wireless interface, the transceiver element and controller being further configured to: determine that one or more acknowledgement feedbacks have not been received from the communications device; transmit, to the communications device, a retransmission request; transmit, to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; and receive, from the communications device and in response to the retransmission request, a report comprising feedback information.

15. Circuitry for a network node for use in a mobile telecommunications network, the network comprising a communications device and the network node, the network node being configured to provide a wireless interface to the communications device, wherein the circuitry comprises a controller element and a transceiver element configured to operate together to communicate with the communications device via the wireless interface and wherein the controller element and the transceiver element are further configured to operate together to determine that one or more acknowledgement feedbacks have not been received from the communications device; transmit, to the communications device, a retransmission request; transmit, to the communications device, an indication indicating the one or more acknowledgement feedbacks to be retransmitted; and receive, from the communications device and in response to the retransmission request, a report comprising feedback information.

16. A method of operating a communications device in a telecommunications network, the telecommunications network comprising a network node arranged to communicate with the communications device via a wireless interface, the method comprising: receiving, from the network node, a retransmission request; receiving, from the network node, an indication indicating one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, determining whether a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more first acknowledgement feedback has been received; and reporting feedback information to the network node, wherein, if the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received.

17. A communications device for use in a telecommunications network, the communications device comprising a transceiver element and controller configured to operate together to communicate with a network node of the telecommunications network via a wireless interface provided by the network node, the transceiver element and controller being further configured to: receive, from the network node, a retransmission request; receive, from the network node, an indication indicating one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, determine whether a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more first acknowledgement feedback has been received; and report feedback information to the network node, wherein if the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received.

18. Circuitry for a communications device for use in a mobile telecommunications network, the network comprising the communications device and a network node configured to provide a wireless interface to the communications device, wherein the circuitry comprises a controller element and a transceiver element configured to operate together to communicate with the network node via the wireless interface and wherein the controller element and the transceiver element are further configured to operate together to receive, from the network node, a retransmission request; receive, from the network node, an indication indicating one or more acknowledgement feedbacks to be retransmitted; upon receiving the retransmission request and using the indication, determine whether a first downlink grant for a first downlink transmission corresponding to a first acknowledgement feedback of the one or more first acknowledgement feedback has been received; and report feedback information to the network node, wherein if the communications device determines that it has not received the first downlink grant, the feedback information notifies the network node that the first downlink transmission was not received.

19. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of any one of claims 1, 13 and 16.