Methods, infrastructure equipment, and communications devices

Abstract

A method of operating an infrastructure equipment forming part of a wireless communications network configured to transmit signals to and / or to receive signals from a plurality of communications devices is provided. The method comprises transmitting, to a first of the plurality of communications devices, a first downlink channel comprising first downlink data, and transmitting, to the first communications device before feedback is received from the first communications device in response to the first downlink channel, a second downlink channel, wherein the second downlink channel comprises second downlink data piggybacked onto a retransmission of the first downlink data to the first communications device. Here, the second downlink data is for receipt by one or more target communications devices, the one or more target communications devices being either the first communications device or one or more others of the plurality of communications devices. The first communications device and the one or more other communications devices each form part of a proximity group of a subnetwork of the wireless communications network, the subnetwork comprising at least the first communications device, the one or more other communications devices, and the infrastructure equipment.

Description

[0001] METHODS, INFRASTRUCTURE EQUIPMENT, AND COMMUNICATIONS DEVICESBACKGROUND Field of DisclosureThe present disclosure relates to infrastructure equipment, communications devices, and methods for themore efficient and effective transmission and / or reception of data in a wireless communications network. The present applications claims the Paris Convention priority from European patent application number EP24159502.4, filed on 23 February 2024, the contents of which are hereby incorporated by reference. Description of Related Art 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. Previous generation mobile telecommunication systems, such as those based on the 3GPP defined UMTS and Long Term Evolution (LTE) architecture, are able to support a wider range of services than simple voice and messaging services offered by previous 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 whereaccess to the networks is possible, is expected to continue to increase rapidly.Current and future wireless communications networks are expected to routinely and efficiently support communications with an ever-increasing range of devices associated with a wider range of data traffic profiles and types 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 (MTC) devices, high resolutionvideo displays, virtual reality headsets, eXtended Reality (XR) and so on. Some of these different typesof 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. Other types of device, for example supporting high-definition video streaming, may be associated with transmissions of relatively large amounts of data with relatively low latency tolerance. Other types of device, for example used for autonomous vehicle communications and for other critical applications, may be characterised by data that should betransmitted through the network with low latency and high reliability. A single device type might also beassociated with different traffic profiles / characteristics depending on the application(s) it is running. For example, different considerations may apply for efficiently supporting data exchange with a smartphone when it is running a video streaming application (high downlink data) as compared to when it is running an Internet browsing application (sporadic uplink and downlink data) or being used for voice communications by an emergency responder in an emergency scenario (data subject to stringent reliability and latency requirements). In view of this there is expected to be a desire for current wireless communications networks, for example those which may be referred to as 5G or new radio (NR) systems / new radio access technology (RAT) systems, or indeed future 6G wireless communications, 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. SUMMARY OF THE DISCLOSURE The present disclosure can help address or mitigate at least some of the issues discussed above. Embodiments of the present technique can provide a method of operating an infrastructure equipment forming part of a wireless communications network configured to transmit signals to and / or to receive signals from a plurality of communications devices is provided. The method comprises transmitting, to afirst of the plurality of communications devices, a first downlink channel comprising first downlink data,and transmitting, to the first communications device before feedback is received from the first communications device in response to the first downlink channel, a second downlink channel, whereinthe second downlink channel comprises second downlink data piggybacked onto a retransmission of thefirst downlink data to the first communications device. Here, the second downlink data is for receipt byone or more target communications devices, the one or more target communications devices being eitherthe first communications device or one or more others of the plurality of communications devices. Thefirst communications device and the one or more other communications devices each form part of aproximity group of a subnetwork of the wireless communications network, the subnetwork comprising at least the first communications device, the one or more other communications devices, and the infrastructure equipment. Such embodiments of the present technique, which, in addition to methods of operating infrastructure equipment, relate to methods of operating communications devices, to infrastructure equipment andcommunications devices, to circuitry for infrastructure equipment and communications devices, towireless communications systems, to computer programs, and to computer-readable storage mediums, can allow for the more efficient and effective use of radio resources in a wireless communications network. Respective aspects and features of the present disclosure are defined in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the present technology. The described embodiments, together with further advantages, 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 NR-type wireless telecommunications system whichmay be configured to operate in accordance with certain embodiments of the present disclosure;Figure 2 is a schematic block diagram of an example infrastructure equipment and communications device which may be configured to operate in accordance with certain embodiments of the present disclosure; Figures 3A, 3B, and 3C provide examples of subnetworks in which certain embodiments of the present disclosure may be implemented; Figure 4 illustrates an example of Physical Downlink Shared Channel (PDSCH) Hybrid Automatic Repeat Request (HARQ) transmission;Figure 5 illustrates an example of proximity groups in a subnetwork;Figure 6 shows an example of pre-emptive retransmission and preventive scheduling using proximity grouping;Figure 7 illustrates how a first (“eavesdropping”) user equipment (UE) may decode a PDSCH transmittedto another UE in accordance with embodiments of the present technique;Figure 8 shows how an eavesdropping UE may transmit feedback in response to decoding a PDSCHtransmitted to another UE in accordance with embodiments of the present technique;Figure 9 shows a part schematic, part message flow diagram representation of an example wirelesscommunications system comprising a communications device and an infrastructure equipment in accordance with embodiments of the present technique; Figure 10 illustrates how a UE may indicate a maximum piggybacked modulation and coding scheme (P- MCS) indicator in accordance with embodiments of the present technique; Figure 11 illustrates how additional downlink data for a UE that has indicated a positiveacknowledgement (ACK) for a previous PDSCH may be piggybacked onto a pre-emptive retransmissionPDSCH in accordance with embodiments of the present technique; Figure 12 illustrates how a UE may indicate a level of difficulty or ease of decoding in accordance with embodiments of the present technique;Figure 13 shows how encoded piggybacked data may be added onto a pre-emptive retransmissionPDSCH in accordance with embodiments of the present technique;Figure 14 shows how encoded piggybacked data may be superimposed upon a pre-emptive retransmissionPDSCH in accordance with embodiments of the present technique;Figure 15 shows how encoded piggybacked data and a pre-emptive retransmission PDSCH may be jointlyencoded in accordance with embodiments of the present technique;Figure 16 shows a flow diagram illustrating an example process of communications in a communicationssystem in accordance with embodiments of the present technique;Figure 17 illustrates a first plot of bit-interleaved coded modulation (BICM) capacity provided fordemonstration purposes with respect to embodiments of the present disclosure;Figure 18 illustrates a second plot of BICM capacity provided for demonstration purposes with respect toembodiments of the present disclosure; andFigure 19 illustrates a third plot of BICM capacity provided for demonstration purposes with respect toembodiments of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS New Radio Access Technology (5G) Figure 1 provides a schematic diagram illustrating an example configuration of a wireless communications network which uses some of the terminology used in NR and 5G 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. It will be appreciated that operational aspects of the telecommunications 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. In Figure 1 a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 41, 42 by a connection interface represented as a line 16. In another example, the TRP 10 may be connected to another TRP (not shown in Figure 1) that is connected to DUs 41, 42. This connectivity can be a wireless connectivity. In this example, the TRP 10 can be a non-stationary TRP. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within a radio frequency bandwidth available to the wireless communications network. Thus, within a range for performing radio communications via the wireless access interface, each of the TRPs 10, forms a coverage area (i.e. a cell) of the wireless communications network as represented by a circle 12, within which data can be communicated to and from communications devices 14. As such, wireless communications devices 14 which are within a radio communications range provided by the cells 12 can transmit and receive signals to and from the TRPs 10 via the wireless access interface. Each of the distributed units 41, 42 are connected to a central unit (CU) 40 (which may be referred to as a controlling node) via an interface 46. The central unit 40 is then connected to the core network 20 which may contain all other functions required to transmit data for communicating to and from the wireless communications devices and the core network 20 may be connected to other networks 25. The core network 20 routes data to and from communications devices 14 via the respective distributed units 41, 42 and provides functions such as authentication, mobility management, charging and so on. The core network 20 may further track the location of the communications devices 14 so that it can efficiently contact (i.e., page) the communications devices 14 for transmitting downlink data towards the communications devices 14. The elements of the wireless access network shown in Figure 1 may operate in a similar way to corresponding elements of an LTE network, or future generation mobile communications networks. Itwill be appreciated that operational aspects of the telecommunications network represented in Figure 1,and of other networks discussed herein in accordance with embodiments of the disclosure, 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 currently used approaches for implementing such operational aspects of wireless telecommunications systems, e.g. in accordance with the relevant standards. The respective central units 40 and their associated distributed units / TRPs 10 of Figure 1 may in part have base station functionality. Base stations, which are an example of network infrastructure equipment, may also be referred to as transceiver stations, nodeBs, eNodeBs, eNB, gNodeBs, gNB, Access Points (AP), master or relay user equipment (UE), and so forth. In this regard different terminology is often associated with different generations of wireless telecommunications systems for elements providing broadly comparable functionality. However, 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 (such as gNodeBs or the TRPs of Figure 1) 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. The terms network infrastructure equipment / access node / access point may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between therespective distributed units and the communications devices may lie with the controlling node / centralunit and / or the distributed units / TRPs. Although each TRP / DU is shown in Figure 1 as a single entity, the skilled person will appreciate that some of the functions of the TRP / DU / base station may be carried out by disparate, inter-connected elements, such as antennas (or antennae), remote radio heads, amplifiers, etc. Collectively, one or more base stations may form a radio access network. A communications device 14 is represented in Figure 1 within the coverage area of the first communication cell 12. This communications device 14 may thus exchange signalling with the first central unit 40 in the first communication cell 12 via one of the distributed units / TRPs 10 associated with the first communication cell 12. Communications devices 14 may also be referred to as mobile stations, user equipment (UE), user terminal, mobile radio, terminal device, and so forth. It will further be appreciated that Figure 1 represents merely one example of a proposed architecture for a new RAT based telecommunications 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 telecommunications systems having different architectures. Thus, certain embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems / networks according to various different architectures, such as the example architecture shown in Figure 2. It will thus be appreciated the specific wireless telecommunications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, certain 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 control unit / controlling node 40 and / or a TRP 10 of the kind shown in Figure 1 which is adapted to provide functionality in accordance with the principles described herein. A more detailed diagram of some of the components of the network shown in Figure 1 is provided by Figure 2. In Figure 2, a TRP 10 as shown in Figure 1 comprises, as a simplified representation, a wireless transmitter 30, a wireless receiver 32 and a controller or controlling processor 34 which may operate to control the transmitter 30 and the wireless receiver 32 to transmit and receive radio signals to one or moreUEs 14 within a cell 12 formed by the TRP 10. As shown in Figure 2, an example UE 14 is shown toinclude a corresponding transmitter 49, a receiver 48 and a controller 44 which is configured to control the transmitter 49 and the receiver 48 to transmit signals representing uplink (UL) data to the wireless communications network via the wireless access interface formed by the TRP 10 and to receive downlink (DL) data as signals transmitted by the transmitter 30 and received by the receiver 48 in accordance withthe conventional operation.The transmitters 30, 49 and the receivers 32, 48 (as well as other transmitters, receivers and transceivers described in relation to examples and embodiments of the present disclosure) may include radio frequency filters and amplifiers as well as signal processing components and devices in order to transmit and receive radio signals in accordance for example with the 5G / NR standard. The controllers 34, 44 (as well as other controllers described in relation to examples and embodiments of the present disclosure) may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc., 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. The transmitters, the receivers and the controllers are schematically shown in Figure 2 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 infrastructure equipment / TRP / base station as well as the UE / communications device will in general comprise various other elements associated with its operating functionality. As shown in Figure 2, the TRP 10 also includes a network interface 50 which connects to the DU 42 via a physical interface 16. The network interface 50 therefore provides a communication link for data and signalling traffic from the TRP 10 via the DU 42 and the CU 40 to the core network 20. The interface 46 between the DU 42 and the CU 40 is known as the F1 interface which can be a physical or a logical interface. The F1 interface 46 between CU and DU may operate in accordance with specifications 3GPP TS 38.470 and 3GPP TS 38.473, and may be formed from a fibre optic or other wired or wireless high bandwidth connection. In one example the connection 16 from the TRP 10 to the DU 42 is via fibre optic. The connection between a TRP 10 and the core network 20 can be generally referred to as a backhaul, which comprises the interface 16 from the network interface 50 of the TRP 10 to the DU 42 and the F1 interface 46 from the DU 42 to the CU 40. URLLC and eURLLC Systems incorporating NR technology are expected to support different services (or types of services), which may be characterised by different requirements for latency, data rate and / or reliability. For example, Enhanced Mobile Broadband (eMBB) services are characterised by high capacity with a requirement to support up to 20 Gb / s. The requirements for Ultra Reliable and Low Latency Communications (URLLC) services are for one transmission of a 32 byte packet to be transmitted from the radio protocol layer 2 / 3 SDU ingress point to the radio protocol layer 2 / 3 SDU egress point of theradio interface within 1 ms with a reliability of 1 – 10-5 (99.999 %) or higher (99.9999%) [1].Massive Machine Type Communications (mMTC) is another example of a service which may be supported by NR-based communications networks. In addition, systems may be expected to support further enhancements related to Industrial Internet of Things (IIoT) in order to support services with new requirements of high availability, high reliability, low latency, and in some cases, high-accuracy positioning. Enhanced URLLC (eURLLC) [2] specifies features that require high reliability and low latency, such as factory automation, transport industry, electrical power distribution, etc. in a 5G system. eURLLC is further enhanced as IIoT-URLLC [3]. Future 6G Wireless Communications As described above, several generations of mobile communications have been standardised globally up to now, where each generation took approximately a decade from introduction before the development and introduction of another new generation. For example, generations of mobile communications have moved from the Global System for Mobile Communications (GSM) (2G) to Wideband Code Division Multiple Access (WCDMA) (3G), from WCDMA (3G) to LTE (4G), and most recently from LTE (4G) to NR (5G). The latest generation of mobile communications is 5G, as discussed above with reference to the example configurations of Figures 1 and 2, where a significant number of additional features have beenincorporated in different releases to provide new services and capabilities. Such services include eMBB,IIoT and URLLC as discussed above, but also include such services as 2-step Random Access (RACH), Unlicensed NR (NR-U), Cross-link Interference (CLI) handling for Time Division Duplexing (TDD), Positioning, Small Data Transmissions (SDT), Multicast and Broadcast Services (MBS), Reduced Capability UEs, Vehicular Communications (V2X), Integrated Access and Backhaul (IAB), UE power saving, Non Terrestrial Networks (NTN), NR operation up to 71GHz, IoT over NTN, Non-public networks (NPN), extended Reality (XR) for NR, and Radio Access Network (RAN) slicing. Nevertheless, as in every decade, a new generation (e.g.6G) is expected to be developed and deployed inthe near future (around the year 2030), and will be expected to provide new services and capabilities thatthe current 5G cannot provide. There are discussions on technologies beyond 5G, i.e., 6G, that are expected to have significantly higher throughput, lower latency and higher reliability than 5G services, which are also expected to utilize sub-THz frequencies. One of the functionalities being considered for 6G is operation within a subnetwork. Subnetworks A subnetwork is a localized network of communication points. Subnetworks have the following characteristics: ^Short range (below 10 meters) low transmit power cells;^ Extreme requirements in terms of latency, reliability or data rates, i.e., below 0.1 ms latencies,reliability with a packet error rate of 1 – 10-9 (99.9999999%) reliability, and multi-Gbps datarates. A subnetwork can be defined as having any one or more of these latency, reliability, or data rate requirements; ^Consist of one or multiple access points (AP), e.g., gNBs, with edge processing capabilities; and^ May consist of a large number of low complexity or low cost communications devices, such assensors or actuators. The extreme reliability and latency of the subnetwork links, which can be downlink, uplink, or sidelink, make such subnetworks links suitable for replacing wires, thereby reducing the amount of wiring required in the system, which in some cases, e.g., in a car or robot, would result in a significant reduction of their weights and size. Reducing the amount of wiring required in a system or unit would also make manufacturing and installation of that system or unit easier.Some examples of subnetworks are shown in Figures 3A to 3C. Here, as shown in the example of Figure3A, a car 51 can consist of a subnetwork, where cameras 53, sensors 54 (such as light detection and ranging (LIDAR), temperature, or tyre pressure sensors), and entertainment devices 55 (such as screens or speakers) that are both outside and inside the car 51 together with an AP 52 can form a subnetwork. The wireless links of the subnetwork would significantly reduce the amount of required wiring, and hence weight, in the car 51. In other use-cases, a subnetwork can also be in a living room for the purpose of providing immersive Virtual Reality (VR) entertainment. An example of such a home entertainment based subnetwork 61 is shown in Figure 3B, where a user’s headset 63, movement sensors 64 in the user’s haptic gloves, and a fan 65 that blows wind at intensity depending on the scenario currently being experienced in the immersive VR entertainment content may together all form a subnetwork which connects to multiple APs 62. A subnetwork can also be within a single machine, such as a robot arm 71 as shown in the example of Figure 3C. In the robot arm 71 shown in Figure 3C, the sensors, joints, and pneumatic systems used to control movements, along with one or more APs 72, may together all form a subnetwork. Like in the car 51 as shown in the example of Figure 3A, this may significantly reduce the amount of required wiring, which in turn would allow for the robot arm 80 to be made smaller and lighter. 5G HARQ Transmissions In legacy systems such as 5G, a Hybrid Automatic Repeat Request (HARQ) transmission is used for the transmission of physical channels carrying data, such as Physical Downlink Shared Channels (PDSCHs) and Physical Uplink Shared Channels (PUSCHs). Here, such HARQ transmissions consist, after the initial transmission of the physical channels carrying the data, of HARQ feedback from the receiver and,if necessary, retransmissions from the transmitter. For example, an initial transmission of a physicalchannel may be transmitted to a receiver, and the receiver would feed back an ACK if it successfully decodes the physical channel, or otherwise it feeds back a NACK. A retransmission of the physical channel may be transmitted to the receiver if the HARQ feedback for the previous or initial transmission was a NACK, and here, the receiver would soft-combine the logarithmic likelihood ratio (LLR) soft bits of the retransmitted physical channel with all previous transmissions of the same physical channel. This would thereby increase the signal-to-noise ratio (SNR) of the transmission, and after the soft combining, the receiver then attempts to decode the transmission again. There is typically a configured maximum number of retransmissions of a physical channel before the transmission is abandoned. An example of PDSCH HARQ transmissions in the DL is shown in Figure 4, where a DL Grant carriedby downlink control information (DCI#1) is transmitted to a UE in Slot n to schedule a PDSCH#1 in Slotn+1 with a corresponding PUCCH#1 (i.e. a Physical Uplink Control Channel) in sub-slot m+5 (Slot n+2) to carry the HARQ feedback for PDSCH#1. In the example of Figure 4, the UE fails to decode PDSCH#1 and therefore feeds back a NACK in PUCCH#1. The gNB receiving the NACK would send another DL Grant DCI#3 in Slot n+3 scheduling a retransmission of a PDSCH#1 in the later part of Slot n+3 with a corresponding PUCCH#3 in sub-slot m+9 (Slot n+4). The UE soft-combines PDSCH#1received in Slot n+1 with PDSCH#1 in Slot n+3, thereby increasing the effective SNR of the physicalchannel, and here, the UE successfully decodes PDSCH#1 and so feeds back an ACK using PUCCH#3. The total time required for the UE to successfully receive PDSCH#1 is the time between t3and t12. The HARQ Round Trip Time (RTT) is the time between the transmission of the PDSCH and its following retransmission. For example, for PDSCH#1, the HARQ RTT is the time between time t3and t11, whichconsists of processing time at both the UE and gNB. A Send and Wait (SAW) mechanism is employedfor HARQ transmissions, where during the HARQ RTT of one HARQ process, another HARQ process can occur so that the resources can be fully utilised for data transmissions. In the example of Figure 4, during the HARQ RTT for PDSCH#1, another HARQ process for PDSCH#2 can occur, where here, DL Grant DCI#2 in Slot n+1 schedules a PDSCH#2 in Slot n+2 with a corresponding PUCCH#2 in sub-slot m+8 (Slot n+4), where PDSCH#2 occurs between the initial PDSCH#1 in Slot n+1 and the PDSCH#1 retransmission in Slot n+3. The gNB and the UE keep track of the HARQ process using a HARQ Process Number (HPN), and the UE maintains a soft buffer for each HARQ process for soft combining.HARQ transmissions in the uplink for PUSCH is similar to those in the downlink for PDSCH asdescribed above. The 6G subnetwork has a target of extremely high reliability and low latency as noted above, and so the legacy 5G HARQ transmission techniques may not meet such a high demand. Although the reliability may individually be reached by having a high number of retransmissions in 5G, each retransmission introduces latency due to the time required for decoding at the gNB or UE. For the PDSCH case, the HARQ feedback from the UE is issued before a retransmission can occur. Hence, there is motivation to improve the legacy HARQ transmission techniques currently employed in 5G for future use cases in 6G subnetworks. Proximity Grouping in Subnetworks Proximity grouping of UEs in a subnetwork was introduced in co-pending European Patent Application No. EP23181917.8 [4], the contents of which are hereby incorporated by reference. In such proximity groups, two or more UEs that have similar radio channel conditions are grouped by the Access Point (AP)or gNB such that the AP or gNB can estimate the channel condition of the UEs in the proximity groupbased on known channel conditions of one or more UEs in that proximity group.An example is shown in Figure 5, where a subnetwork consists of an AP 80 and five UEs 83-87. Here,the five UEs are divided into two proximity groups 81, 82, where the first proximity group 81 consists of UE183, UE284, and UE385, and the second proximity group 82 consists of UE486 and UE587. The UEs in a proximity group have similar radio conditions and, in the example of Figure 5, the UEs 83-87 are also within a small area in the subnetwork. Proximity grouping of UEs is deemed more feasible in asubnetwork with a small coverage where UEs likely have line-of-sight (LOS) with the AP than in acellular network in an urban environment. In the example of Figure 5, the proximity groups 81, 82 are formed in such a way that UEs with similar physical positions are grouped together. However, it would be appreciated that this may not always be the case, and may only be the case in the example of Figure 5 because the AP 80 is located in a relatively central physical position to each of the UEs 83-87. In other examples to that of Figure 5, the proximity grouping may be carried out by the AP 80 on the basis of similar channel characteristics / radio conditions of UEs, or on a combination of such channel characteristics and the physical locations of those UEs. Proximity grouping enables the gNB / AP scheduler to perform pre-emptive retransmission and preventive scheduling. When performing pre-emptive retransmission, the gNB schedules a retransmission for a PDSCH to a UE before receiving the HARQ feedback from that UE in response to the initial transmission of that PDSCH. When performing preventive scheduling, the gNB schedules a more robust PUSCH / PDSCH (for example with repetitions, or a lower MCS, or a higher transmit power) to a UE than initially scheduled if the gNB learns in the interim that another UE in the same proximity group has experienced or is experiencing poor radio conditions, to improve likelihood of successful transmission / reception of that PUSCH / PDSCH. An example is shown in Figure 6, where UE191, UE292 and UE393 are in the same proximity group.The gNB transmits two DL Grants DCI#1 and DCI#2 in Slot n to schedule PDSCH#1 and PDSCH#2 forUE191 and UE292 in Slot n and Slot n+2 respectively. UE191 fails to decode PDSCH#1 and feedsback a NACK in PUCCH#1 in uplink Slot n+1. Since UE191 and UE292 belong to the same proximity group and UE191 fails to decode PDSCH#1, the gNB estimates that UE292 is also likely to fail to decode PDSCH#2 (which has a similar MCS to PDSCH#1). Consequently, the gNB transmits DCI#4 in Slot n+2 to schedule a pre-emptive retransmission of PDSCH#2 in Slot n+3 for UE292 before receiving any HARQ feedback from UE292. The gNB also transmits DCI#3 in Slot n+2 to schedule a retransmission for PDSCH#1 in Slot n+4 for UE191. In Slot n+3, the gNB wishes to schedule PDSCH#3 to UE393 and, learning from the feedback from UE191 in Slot n+1, the gNB schedules PDSCH#3 with 2× repetitions in Slot n+3 and Slot n+4, to improve PDSCH#3 reliability. That is, the gNB performspreventive scheduling to prevent UE393 from having the same decoding outcome as UE191 did indecoding a single instance of PDSCH#1. Eavesdropping UE The configuration of one or more “eavesdropping UEs” within a proximity group was introduced in co-pending European Patent Application No. EP24152458.6 [5], the contents of which are herebyincorporated by reference. Here, such eavesdropping UEs can (at least partially) decode the downlink channels or signals transmitted by the network to other (target) UEs within the same proximity group. An eavesdropping UE can then transmit the (at least partially) decoded DL channel to the target UE for which DL channel is intended. This increases the reliability of the DL channel. The eavesdropping UE may also transmit HARQ feedback in respect of the DL channel to the AP. An example is shown in Figure 7, where a subnetwork consists of five UEs 103-107 and an AP 100. UE1 103, UE2104 and UE3105 form a first proximity group 101, whilst UE4106 and UE5107 form a second proximity group 102. The AP 100 transmits a PDSCH 108 to UE1103, and here, UE2104 andUE3105 – which both belong to the same proximity group 101 as UE1103 – can also receive thePDSCH 108 and can at least partially decode it, if they are configured as eavesdropping UEs. Although UE1103 and UE3105 may have similar channel profiles, UE3105 is closer to the AP 100 than UE1103 and so UE3105 may have a better received signal strength than UE1103. UE3105 here may therefore act as an eavesdropping UE and so may be provided with the scheduling details of the PDSCH 108 and so can received and decode the PDSCH 108 scheduled for UE1103. If UE3105 successfully decodes the PDSCH 108, it may transmit the PDSCH 108 to UE1103 via sidelink communications. UE1103 may treat the PDSCH 108 from UE3105 as a form of repetition, and so can use it to combine with the PDSCH 108 it receives directly from the AP 100 to improve the decoding outcome of the PDSCH 108. Furthermore, following (successful or unsuccessful) decoding of the PDSCH 108, UE3105 may transmit HARQ feedback to the AP 100 in respect of the decoding outcome. It should be appreciated that for extreme reliability, such as where the target BLER is 10-9or tighter, it may take a very long time for the scheduler to determine whether a UE is hitting the BLER target, sincethe scheduler may need to count the number of packets received with errors over the total number ofpackets received in order to determine a BLER value. For example, depending on the link adaptation method employed, in the worst case, the scheduler may need to receive at least one billion packets to determine whether or not the UE has achieved the BLER target. Such procedures as those proposed in [5]would increase the number of packets received per UE – since a PDSCH that is targeted at one UE canalso be decoded by other UEs in the same proximity group – thereby providing additional HARQfeedback to the scheduler to update its link adaptation in a quicker and more efficient manner. That is,instead of relying on a single UE to determine whether it achieves a stringent BLER target, the networkmay be able to determine the BLER of multiple UEs in a proximity group from the HARQ feedback received from these UEs. The eavesdropped HARQ feedback is also useful for the AP scheduler in scheduling packets for the eavesdropping UEs (in addition to the targeted UE) in the near future. An example is shown in Figure 8, where UE1111, UE2112, and UE3113 are in the same proximity group, in the same manner as UE1103, UE2104, and UE3105 in the example of Figure 7. In thisexample, UE1111 is the target UE and UE2112 and UE3113 are the eavesdropping UEs. The APschedules PDSCH#1 to UE1111 in Slot n and PDSCH#2 to UE2112 in Slot n+2. Since UE2112 andUE3113 are in the same proximity group as UE1111, they also attempt to decode PDSCH#1 and theysend the decoding outcome, i.e., HARQ feedback, to the AP. In this example, UE1111 fails to decode PDSCH#1 that the AP schedule for it, and so it feeds back a NACK in PUCCH#1 in uplink Slot n+1. UE2112 also fails to decode PDSCH#1, and so it feeds back a NACK in PUCCH#2 in uplink Slot n+1. UE3113, which is closer to the AP than UE1111 or UE2112, manages to decode PDSCH#1, and so it feeds back an ACK in PUCCH#3 in uplink Slot n+1. The AP may then schedule a retransmission of PDSCH#1 in Slot n+4 for UE1111. The AP, learning that UE2112 also failed to decode PDSCH#1, may schedule a pre-emptive retransmission for PDSCH#2 in Slot n+3 to UE2112. In Slot n+3, the APschedules PDSCH#3 to UE3113, and since it learned that UE3113 managed to decode PDSCH#1successfully and PDSCH#3 has similar a MCS as PDSCH#1, it schedules a single PDSCH#3 instance to UE3113 (instead of a PDSCH with 2× repetition, as in the example in Figure 6). A general technical issue addressed through the use of proximity grouping in subnetworks then is that latency can be reduced and more efficient resource usage can be enabled, because techniques such asthose described above relating to pre-emptive retransmission for example allow for faster retransmissionsin 6G systems, especially for such 6G subnetworks that require extreme reliability and low latency. However, such techniques introduce a separate issue in respect of efficiency. That is, since pre-emptive retransmissions are based on prediction, despite reducing latency, such predictions may sometimes be wrong. That is, a pre-emptive retransmission in some cases may be scheduled when not required, which will lead to a waste of resources. A technical issue to solve then in respect of the use of pre-emptive retransmissions is how to reduce the wasting of resources for unwanted or unnecessary pre-emptive retransmissions. Embodiments of the present technique seek to provide solutions to such a technical issue. Piggyback on Pre-Emptive RetransmissionFigure 9 shows a part schematic, part message flow diagram representation of a first wirelesscommunications system comprising a first communications device 121 (e.g. a UE 14), an infrastructure equipment 122 (e.g. an AP such as a gNB / TRP 10), and a second communications device 123 (e.g. a UE 14) in accordance with at least some embodiments of the present technique. The first communications device 121 may be configured to transmit signals to and / or receive signals from the wireless communications network, for example, to and from the infrastructure equipment 122. Specifically, the first communications device 121 may be configured to transmit data to and / or receive data from the wireless communications network (e.g. to / from the infrastructure equipment 122) via a wireless radio interface provided by the wireless communications network (e.g., a Uu interface between the first communications device 121 and a node of a Radio Access Network (RAN), i.e. the infrastructureequipment 122). The first communications device 121 may also be configured to transmit signals toand / or receive signals from the second communications device 123. Specifically, the firstcommunications device 121 may be configured to transmit data to and / or receive data from the secondcommunications device 123 via a sidelink interface between the first communications device 121 and the second communications device 123. The second communications device 123 may also be configured to transmit data to and / or receive data from the wireless communications network (e.g. to / from the infrastructure equipment 122) via a wireless radio interface provided by the wireless communications network (e.g., a Uu interface between the second communications device 123 and a node of the Radio Access Network (RAN), i.e. the infrastructure equipment 122). Here, the first communications device 121 and the second communications device 123 each form part of a proximity group of a subnetwork 124 of the wireless communications network, the subnetwork 124 comprising at least the first communications device 121, the second communications device 123, and the infrastructure equipment 122. The first communications device 121, the infrastructure equipment 122, and the second communications device 123 each comprise a transceiver (or transceiver circuitry) 121.1, 122.1, 123.1, and a controller (or controller circuitry) 121.2, 122.2, 123.2. Each of the controllers 121.2, 122.2, 123.2 may be, for example,a microprocessor, a CPU, or a dedicated chipset, etc. The controllers 121.2, 122.2, 123.2 may also eachbe equipped with a memory unit (which is not shown in Figure 9). As shown in the example of Figure 9, the transceiver circuitry 122.1 and the controller circuitry 122.2 ofthe infrastructure equipment 122 are configured in combination to transmit 125, to the firstcommunications device 121, a first downlink channel comprising first downlink data, and to transmit 126,to the first communications device 121 before feedback is received from the first communications device121 in response to the first downlink channel 125, a second downlink channel, wherein the seconddownlink channel comprises second downlink data piggybacked onto a retransmission of the firstdownlink data to the first communications device 121. Here, the second downlink data is for receipt byone or more target communications devices, where the one or more target communications devices areeach either the first communications device or a second (or one or more others) of the plurality ofcommunications devices.In the example of Figure 9, there is only one target communications device of the second downlink data,where that target communications device is the second communications device 123, although thoseskilled in the art would appreciate that the target communications device of the second downlink data may, in other examples of embodiments of the present technique to that shown by Figure 9, be the first communications device 121 (i.e. the same UE to which the retransmission of the first downlink data is transmitted is the target of the second downlink data piggybacked onto that retransmission of the first downlink data), or there may be multiple target communications devices, when the infrastructure equipment 122 for example has some control information to provide or a message to broadcast to multiple UEs within a proximity group, and in accordance with embodiments of the present technique, is able to piggyback this information or message onto a downlink data channel carrying the retransmission of different downlink data. Here, one of those multiple target communications devices may in some examples be the first communications device 121 (i.e. the same UE to which the retransmission of the first downlink data is transmitted is the target of the second downlink data piggybacked onto thatretransmission of the first downlink data). Here, such a target communications device – i.e. the target ofthe second downlink data – is not to be confused with such a target UE as that described above withrespect to the examples of Figures 8 and 9, where such a target UE is the target of a PDSCH that may be received at least in part by an eavesdropping UE within the same proximity group. In the example of Figure 9, where the target communications device is the second communications device 123, the second communications device 123 may also be an eavesdropping UE (in addition to being the target of the second downlink data) as it is able to receive and decode the second downlink channel comprising the retransmission of the first downlink data targeted at the first communications device 121, so as to receive the piggybacked second downlink data. Essentially then, embodiments of the present technique, as exemplified by the example wirelesscommunications system of Figure 9 for example, propose that data (i.e. the second downlink data in theexample of Figure 9) is piggybacked onto a pre-emptive retransmission (i.e. of the first downlink data inthe example of Figure 9). Hence, if the pre-emptive retransmission to a UE is not needed, i.e., in the casethat the UE managed to decode the DL channel in a previous transmission (i.e. initial transmission or aprevious retransmission), then the transmission is not entirely wasted, as it carries additional data. Here,the piggybacked data (i.e. the second downlink data) can be control information or user / applicationinformation, and can be targeted to one or more UEs in the proximity group, which may or may not include the UE for which the pre-emptive retransmission is scheduled.In some arrangements of embodiments of the present technique, the UE (i.e. the target communicationsdevice) indicates whether it can receive a transmission that is piggybacked onto another transmission suchas the pre-emptive retransmission PDSCH. In other words, the infrastructure equipment may beconfigured to receive, from the one or more target communications devices, a piggybacking indicator,wherein the piggybacking indicator indicates whether the one or more target communications devices areable to receive the second downlink data when it is piggybacked onto the retransmission of the first downlink data, and to perform the piggybacking of the second downlink data onto the retransmission ofthe first downlink data if the piggybacking indicator indicates that the one or more target communicationsdevices are able to receive the second downlink data when it is piggybacked onto the retransmission ofthe first downlink data.In some examples, the UE may indicate such a piggybacking indicator via its capability. For example,such a capability may relate to whether the UE has features (including hardware functions) to support inprocessing the receive a transmission that is piggybacked onto another transmission. In other words, thepiggybacking indicator may comprise a capability of the one or more target communications devices toprocess downlink transmissions that are piggybacked onto other downlink transmissions (such as thesecond downlink data, or in general, any user or control data piggybacked onto other downlinktransmissions targeted at other communications devices, within the same proximity group, for example). Additionally, or alternatively, the indication can be further provided based on certain conditions, such as the radio condition / radio channel quality. The UE may determine this by evaluating its radio condition, such as the interference level or from a previous PDSCH decoding. If the UE can perform eavesdropping, it can also evaluate the interference caused by other UE’s PDSCH in recent DL slots. In some arrangements of embodiments of the present technique, the said piggyback indicator is a maximum piggybacked MCS (P-MCS). The P-MCS indicates the maximum MCS the UE can decode within a targeted BLER for a PDSCH that is piggybacked onto another transmission. In other words, the piggybacking indicator may comprise a maximum piggybacked modulation and coding scheme (MCS) that, if the second downlink data had been transmitted in accordance with the maximum piggybackedMCS, the one or more target communications devices would have been able to successfully receive thesecond downlink data piggybacked onto the retransmission of the first downlink data within the second downlink channel in accordance with a predefined error rate. The AP can then determine the MCS level it can use on the additional data that is piggybacked onto a pre-emptive retransmission PDSCH.An example is shown in Figure 10, where a first UE 131 and a second UE 132 belong to the sameproximity group. The AP transmits DCI#1 and DCI#2 to schedule PDSCH#1 in Slot n and PDSCH#2 inSlot n+2 to the first UE 131 and the second UE 132 respectively. PDSCH#1 and PDSCH2 are scheduledwith MCS = 4. The first UE 131 successfully decodes PDSCH#1 and therefore feeds back an ACKtogether with an indication of its maximum piggybacked MCS, P-MCS = 6 in PUCCH#1 in UL Slot n+1.The second UE 132 eavesdrops on PDSCH#1 but fails to decode it, and so feeds back a NACK inPUCCH#2 in UL Slot n+1. The AP schedules a pre-emptive retransmission for PDSCH#2 in Slot n+3.Since the first UE 131 is able to decode a piggybacked PDSCH if its MCS is equal to or below 6 (i.e., P-MCS = 6), the AP schedules PDSCH#3 with MCS = 3, where PDSCH#3 is piggybacked onto PDSCH#2,i.e., PDSCH#3 and PDSCH#2 share the same resource elements (REs). As those skilled in the art would appreciate, the P-MCS may change for a UE over time, as the UE moves for example, as channel conditions change. Therefore, the P-MCS may be indicated to the AP in any one or more of a number of different suitable ways. For example, the P-MCS can be transmitted to the APperiodically, semi-persistently (i.e. activated by a DCI and deactivated by another DCI), a-periodically(for example, sent once when indicated to do so by a DCI), and / or triggered by another signal or event,for example, triggered by the sending of a HARQ-ACK by the UE, where the UE transmits an indicationof the P-MCS together with the HARQ-ACK.In some arrangements of embodiments of the present technique, the AP determines whether to transmits piggyback data onto a pre-emptive retransmission PDSCH based on UE reported maximum MCS. Maximum MCS (Max MCS) is introduced in [4], where the UE indicates the maximum MCS in a PDSCH that it can tolerate within a predefined time period. In other words, the piggybacking indicator may comprise a maximum MCS that, if the second downlink data had been transmitted in accordancewith the maximum MCS, the one or more target communications devices would have been able tosuccessfully receive the second downlink data in accordance with a predefined error rate. Here, the indication of the maximum MCS indicates that, if the second downlink data had been transmitted inaccordance with an MCS higher than the maximum MCS, the one or more target communications deviceswould not have been able to successfully receive the second downlink data in accordance with the predefined error rate.It would be appreciated by those skilled in the art the maximum MCS (Max MCS) here is different to theP-MCS described above with respect to the example of Figure 10. The P-MCS is the max MCSspecifically for a PDSCH that is piggybacked onto another transmission, whilst the Max MCS is simplythe maximum MCS of a PDSCH without any piggybacking onto another transmission. Based on the Max MCS, the AP can decide on the MCS used on the additional data that is piggybacked onto a pre-emptive retransmission PDSCH. Here the AP may apply an offset to the Max MCS, e.g. if UE reported Max MCS = 6, the AP may apply an offset of 2 MCS, and so would not schedule a PDSCH with MCS > 4 to be piggybacked onto a pre-emptive retransmission PDSCH. As those skilled in the art would appreciate, in the same manner as the P-MCS as described above, the Max MCS may change for a UE over time, as the UE moves for example, as channel conditions change. Therefore, the Max MCS may be indicated to the AP in any one or more of a number of different suitable ways. For example, the Max MCS can be transmitted to the AP periodically, semi-persistently (i.e. activated by a DCI and deactivated by another DCI), a-periodically (for example, sent once when indicated to do so by a DCI), and / or triggered by another signal or event, for example, triggered by the sending of a HARQ-ACK by the UE, where the UE transmits an indication of the Max MCS together with the HARQ-ACK. In some arrangements of embodiments of the present technique, the AP determines whether to transmits piggyback data onto a pre-emptive retransmission PDSCH based on a-UE reported MCS. Typically, the UE reports an MCS by indicating an index of a channel quality indicator (CQI) table that points to thatMCS, and the UE may send such an MCS together with the HARQ ACK / NACK for a received PDSCH.In other words, the piggybacking indicator comprises a channel quality indicator (CQI) index indicating an MCS. The AP can then determine based on the MCS whether the UE can decode a piggybackedPDSCH. It should be noted that this MCS is the legacy MCS, which is different to the P-MCS and MaxMCS as described above. The legacy MCS can already be sent periodically, semi-persistently and a-periodically. Here we also include a triggered based MCS where it is transmitted together with a HARQ- ACK / NACK. It should be appreciated that the P-MCS offers more accurate information for the AP as compared to MaxMCS, and similarly, the Max MCS offers more accurate information to the AP as compared to the legacyMCS. On the other hand, the UE may have to perform more processing to determine the P-MCS and Max MCS as compared to using the legacy MCS. In some arrangements of embodiments of the present technique, the said piggybacked data is transmittedto a UE in the proximity group if it has indicated an ACK in a previous PDSCH. In other words, thepiggybacking indicator may comprise an acknowledgement feedback signal (e.g. a HARQ ACK / NACK)transmitted by the one or more target communications devices to the infrastructure equipment in responseto a previous downlink channel transmitted by the infrastructure equipment to the one or more targetcommunications devices.An example is shown in Figure 11, where a first UE 141, a second UE 142, and a third UE 143 are in aproximity group as shown in Figure 7. The AP transmits DCI#1 and DCI#2 in Slot n to schedulePDSCH#1 in Slot n and PDSCH#2 in Slot n+2, for the first UE 141 and the second UE 142 respectively.For PDSCH#1, the first UE 141 is the target UE, and here it fails to decode PDSCH#1 and so feeds backa NACK in PUCCH#1 in UL Slot n+1. The second UE 142 and the third UE 143 are eavesdropping UEs,and so they also attempt to decode PDSCH#1. The second UE 142 fails to decode PDSCH#1 andtherefore feeds back NACK in PUCCH#2 in UL Slot n+1 but the third UE 143 successfully decodesPDSCH#1 and so feeds back an ACK in PUCCH#3 in UL Slot n+1. Employing the method first definedin [5] and described above with respect to Figures 7 and 8, the AP schedules a pre-emptive retransmissionfor PDSCH#2. As per these arrangements, since the third UE 143 successfully decoded PDSCH#1, theAP piggybacks PDSCH#3 onto the pre-emptive retransmission of PDSCH#2.Such arrangements recognise that a UE that provides an ACK for the PDSCH, especially for the samePDSCH, is likely to be closer to the AP, e.g., in the example of Figure 11, the third UE 143 is closer tothe AP than the second UE 142 is, and so the piggybacked data, e.g., PDSCH#3, can be transmitted at alower power to reduce interfering with the pre-emptive retransmission PDSCH, e.g., PDSCH#2.Furthermore, since the third UE 143 managed to decode PDSCH#1 successfully, it is likely also able toeavesdrop on PDSCH#2 and decodes that successfully in Slot n+2. This is beneficial as the third UE 143can then use the decoded PDSCH#2 in Slot n+2 to remove the pre-emptive retransmission PDSCH#2 inSlot n+3, thereby increasing its chances in successfully decoding the additional data PDSCH#3. That is,the third UE 143 may re-encode PDSCH#2 and use that as input for a Successive InterferenceCancellation (SIC) receiver to remove the pre-emptive retransmission PDSCH#2, so that it has aPDSCH#3 that has a much lower level of interference.In some arrangements of embodiments of the present technique, the UE indicates a level of difficulty or ease in decoding the PDSCH. In other words, the acknowledgement feedback signal may comprise anindication of a level of difficulty of decoding of the previous downlink channel by the one or more targetcommunications devices. That is, if the acknowledgement feedback signal (e.g. HARQ feedback) is anACK, the UE indicates how strong an ACK it is, for example, in view of the number of iterations it needsin the low density parity check (LDPC) channel decoding, where the lower the number of iterations, theeasier it is for the UE to decode the PDSCH. Similarly, if the UE sends a NACK, it also indicates howclose it was in decoding the PDSCH. The UE may (additionally) consider the soft bits (LLRs) whenestimating the level of difficulty / ease in decoding the packet. This can be viewed as a soft HARQfeedback. An implementation of such arrangements is to indicate a number, e.g., two bits, where 00 =very difficult to decode (i.e., resulting in NACK), 01 = close to decoding the PDSCH (also a NACK), 10= just managed to decode it (i.e. an ACK), and 11 = easily decoded (also an ACK). The AP can then usethis level to determine whether to send a piggybacked PDSCH onto a pre-emptive retransmission PDSCH to that UE.An example is shown in Figure 12, where a first UE 151, a second UE 152, and a third UE 153 belong tothe same proximity group. The AP schedules PDSCH#1 in Slot n and PDSCH#2 in Slot n+2 for the firstUE 151 and the second UE 152 respectively. The first UE 151 manages to decode PDSCH#1, and sofeeds back an ACK in PUCCH#1 in UL Slot n+1. As per these arrangements, the first UE 151 alsoindicates the level of difficulty in decoding PDSCH#1, and here a two-bit indicator is used and the firstUE 151 indicates Level = 10 (i.e., an ACK where the first UE 151 just managed to decode PDSCH#1).The second UE 152 and the third UE 153 eavesdrop on PDSCH#1, where the second UE 152 fails todecode PDSCH#1 whilst the third UE 153 does successfully decode PDSCH#1 with ease. The secondUE 152 feeds back a NACK in PUCCH#2 in UL Slot n+1 and also indicates its level as Level = 01,indicating it only just failed to decode PDSCH#1. The third UE 153 however feeds back an ACK inPUCCH#3 in UL Slot n+1 and also indicates a Level = 11, indicating that it successfully decodedPDSCH#1 easily. The AP schedules a pre-emptive retransmission for PDSCH#2 in Slot n+3. Althoughboth the first UE 151 and the second UE 153 indicated an ACK for the decoding of PDSCH#1, the APschedules PDSCH#4 for the third UE 153 to piggyback onto the pre-emptive retransmission of PDSCH#2in Slot n+3 since the third UE 153 indicated a higher level of ACK than the first UE 151, and so it makesmore sense to use the retransmission of PDSCH#2 to piggyback PDSCH#4 for the third UE 153 andtransmit a future PDSCH#3 to the first UE 151 as a standalone PDSCH. It should be noted that differentnumber of bits can be used to indicate the level of difficulty / ease in decoding a PDSCH, that is, it can bemore than two bits. The example of using two bits is use one possible implementation.It should be appreciated that indicating the level of difficulty / ease in decoding a PDSCH can also be used by the AP to determine whether to piggyback data onto a pre-emptive retransmission PDSCH. Forexample, the second UE 152 in Figure 12 indicates a Level = 01 with a NACK, which suggests it almostdecoded PDSCH#1, which was targeted to the first UE 151 rather than the second UE 152. Here thesecond UE 152 may not need a retransmission for PDSCH#2 as it has a good chance of decoding it sincePDSCH#2 is specifically targeted to the second UE 152, and so adding piggybacked data onto thePDSCH#2 retransmission will reduce wastage. The AP may also determine that since the second UE 152almost decoded PDSCH#1, it is more able to tolerate interference caused by piggybacking data on theretransmission of PDSCH#2. It should be appreciated the arrangements of embodiments of the present technique relating to the piggyback indications as described above can be implemented individually or combined. For example,the level of difficulty / ease of decoding can be indicated in a combined manner with Max Piggyback MCS(P-MCS), which would therefore provide more information for the AP to decide on the scheduling of thepiggybacked data onto a pre-emptive retransmission PDSCH. Where there are multiple target UEs of theadditional (i.e. second) downlink data, one or more of those multiple target UEs may provide an individual or combined piggyback indicator in a different manner to the individual or combined piggyback indicator provided by one or more others of those multiple target UEs.In some arrangements of embodiments of the present technique, the piggybacked data is encoded first andthen added to the pre-emptive retransmission PDSCH at the physical layer. The encoded piggybacked data occupies a subset of the physical resources of the pre-emptive retransmission PDSCH. In other words, the infrastructure equipment may be configured to perform the piggybacking of the second downlink data onto the retransmission of the first downlink data by adding the second downlink data to a subset of a set of downlink resources scheduled for the transmission of the second downlink channel (i.e.,such that this subset of the set of downlink resources comprises only the second – i.e. piggybacked –downlink data). The pre-emptive retransmission PDSCH can rate match around these physical resources. Alternatively or additionally, the encoded piggybacked data can puncture the pre-emptive retransmission PDSCH. An example is shown in Figure 13, where the piggybacked data information bits = {a1, a2, a3, a4, …, an} are encoded giving modulated symbols {b1, b2, b3, b4, …, bm}. The pre-emptive retransmission PDSCH information bits = {c1, c2, c3, c4, …, ck} are independently encoded giving modulated symbols {d1, d2, d3,d4, …, dj} and they are mapped to the Resource Elements (REs), i.e., frequency and time physicalresources, scheduled for the PDSCH. The modulated bits of the piggybacked data are then added todesignated REs of the PDSCH. In this example, the PDSCH is rate matched around the encodedpiggybacked data. Since the piggybacked data occupies REs from the PDSCH, the amount of data cannot be too large as it would take away too many REs from the PDSCH leading to very high code rate. Hencesuch arrangements, albeit not intended to be so restricted, are suitable for small application data or controlinformation. In some arrangements of embodiments of the present technique, the piggybacked data is superimposed onto the pre-emptive retransmission PDSCH. In other words, the infrastructure equipment may be configured to perform the piggybacking of the second downlink data onto the retransmission of the first downlink data by superimposing the second downlink data onto the first downlink data within a set of downlink resources scheduled for the transmission of the second downlink channel (i.e., such that all REs of the set of downlink resources comprise both the first and second downlink data). This method enables more piggybacked data bits to be transmitted compared to the previous method where the pre-emptive retransmission PDSCH is punctured or rate matched around the piggybacked data. An example is shown in Figure 14, where the said piggybacked data is encoded to modulated symbols{b1, b2, b3, b4, …, bm} and the pre-emptive retransmission PDSCH is encoded to modulated symbols {d1,d2, d3, d4, …, dj}, are then added together where both sets of modulated symbols occupy the same REs.The superimposed signals in the same REs are then transmitted to the UEs in the proximity group. In some arrangements of embodiments of the present technique, the said superimposed piggybacked data on the pre-emptive retransmission PDSCH are Code Division Multiplexed (CDM) together. In other words, the superimposing the second downlink data onto the set of downlink resources scheduled for the retransmission of the first downlink data may comprise the second downlink data and the retransmission of the first downlink data being code division multiplexed together before transmission of the second downlink channel. In some arrangements of embodiments of the present technique, the said superimposed piggybacked data on the pre-emptive retransmission PDSCH is to multiplex them in the spatial domain, i.e., single usermultiple input multiple output (SU-MIMO) or multi user MIMO (MU-MIMO). In other words, thesuperimposing the second downlink data onto the set of downlink resources scheduled for the retransmission of the first downlink data may comprise the second downlink data and the retransmission of the first downlink data being spatially multiplexed together before transmission of the second downlinkchannel. Here, the AP provides additional demodulation reference symbols (DMRS) for thesuperimposed piggybacked data so that the UE can extract the said additional data from the pre-emptive retransmission PDSCH. In some arrangements of embodiments of the present technique, the said superimposed piggybacked data on the pre-emptive retransmission PDSCH is to transmit the encoded piggybacked data and encoded pre- emptive retransmission together. In other words, the transmitting the second downlink channel may comprise transmitting the second downlink channel without performing multiplexing on the second downlink data and the retransmission of the first downlink data after performing the piggybacking. Thatis, the piggybacked data and the retransmission PDSCH are transmitted without code divisionmultiplexing or spatial division multiplexing or the like. They then act as interference to each other. Thereceiver at the UE(s) can then perform interference cancellation, such as Successive InterferenceCancellation (SIC), to extract each set of data.In some arrangements of embodiments of the present technique, the piggybacked data and pre-emptive retransmission PDSCH are jointly modulated. In other words, the superimposing the second downlink data onto the set of downlink resources scheduled for the retransmission of the first downlink data may comprise the second downlink data and the retransmission of the first downlink data being jointly modulated before transmission of the second downlink channel. That is the encoded piggybacked data {e1, e2, e3, …, em} and the encoded pre-emptive retransmission PDSCH {f1, f2, f3, f4, …, fk} are fed into a bit to symbol mapper prior to being modulated into a modulated symbol {g1, g2, g3, g4, …, gi}. An example is shown in an example in Figure 15. In the example in Figure 15, the piggybacked data and the pre-emptive retransmission PDSCH both used QPSK modulation and the resultant joint modulatedsymbol is 16QAM. Here, each 16QAM modulated symbol consists of two encoded bits frompiggybacked data and two encoded bits from the pre-emptive retransmission PDSCH. The UE isinformed which two bits of the modulated symbol belong to the piggybacked data and which two bitsbelong to the pre-emptive retransmission PDSCH. It should be noted that other modulation schemes canbe used, and also that the modulation scheme used for the piggybacked data and for the pre-emptiveretransmission PDSCH do not need to be the same, e.g., the piggybacked data may use QPSK whilst pre- emptive retransmission uses 16QAM, and the resultant modulation may be 32QAM or 64QAM, wheremore bits belong to the pre-emptive retransmission than to the piggybacked data in a single modulatedsymbol or vice-versa.In some arrangements of embodiments of the present technique, the AP indicates whether a scheduled PDSCH is being piggybacked onto another PDSCH. For example, the DCI carrying the DL Grant may have an indicator indicating if the scheduled PDSCH is being piggybacked onto another PDSCH such as a pre-emptive retransmission PDSCH. In other words, the infrastructure equipment may be configured totransmit, to the one or more target communications devices, first downlink control information (DCI)wherein the first DCI schedules the transmission of the second downlink data within the second downlink channel, wherein the first DCI indicates that the second downlink data is piggybacked onto the retransmission of the first downlink data. This enables the UE decoding the PDSCH to use an advanced receiver or decoding method, for example, the UE may use SIC to remove interference caused by the other PDSCH. In some arrangements of embodiments of the present technique, the AP indicates whether a pre-emptive retransmission PDSCH contains piggybacked control information in the DL Grant scheduling the pre- emptive retransmission PDSCH. In other words, the infrastructure equipment may be configured to transmit, to the first communications device, a second DCI which schedules the retransmission of the first downlink data within the second downlink channel, wherein the second DCI indicates that the second downlink data is piggybacked onto the retransmission of the first downlink data. This enables the UE receiving the pre-emptive retransmission PDSCH to rate match or avoid the REs containing the piggybacked control information. The AP needs also to indicate to other UEs that there is control information embedded onto the PDSCH. This can be indicated using for example a GC-DCI e.g. a one- bit indicator indicating whether control information is present or absent in a PDSCH. In some arrangements of embodiments of the present technique, the AP indicates to a group of UEs, such as the UEs in a proximity group, whether a pre-emptive retransmission PDSCH contains piggybacked information in a Group Common DCI. The retransmission PDSCH with piggybacked information may be scheduled by another DCI such as a DL Grant. In other words, the infrastructure equipment may be configured to transmit, to the first communications device, a second DCI which schedules the retransmission of the first downlink data within the second downlink channel, and the infrastructureequipment may be configured to also transmit, to one or more communication devices of the proximitygroup (i.e. to the first communications device and the one or more target communications devices), a thirdDCI which indicates that the second DCI indicates that the second downlink data is piggybacked onto the retransmission of the first downlink data. Here, the third DCI may specifically be a group common DCI (GC-DCI). In some arrangements of embodiments of the present technique, the said piggybacked method (e.g. where the pre-emptive retransmission PDSCH is punctured or rate matched around the piggybacked data or where the piggybacked data is superimposed on the pre-emptive retransmission PDSCH) is indicated in a DCI. For example, the DCI#3 (that schedules the piggybacked data) and DCI#4 (that schedules the retransmission PDSCH) in Figure 10 indicates the piggybacked method to be used for the associatedPDSCH. Here, the first UE 131 and the second UE 132 will be aware that the received PDSCH is apiggybacked transmission. In other words, the first DCI and / or the second DCI may comprise an indication of how the second downlink data is piggybacked onto the retransmission of the first downlink data.In some arrangements of embodiments of the present technique, the said piggybacked method (e.g. wherethe pre-emptive retransmission PDSCH is punctured or rate matched around the piggybacked data orwhere the piggybacked data is superimposed on the pre-emptive retransmission PDSCH) is RRCconfigured by the AP. In other words, the infrastructure equipment may be configured to transmit, to thefirst communications device and / or the one or more target communications devices, radio resourcecontrol, RRC, signalling, wherein the RRC signalling comprises an indication of how the seconddownlink data is piggybacked onto the retransmission of the first downlink data. This can be based onthe UE’s capability signalling, e.g. in respect of whether the UE can perform SIC or not. If the UE cannotperform SIC, the AP may configure the UE to read piggybacked information that is punctured into a pre-emptive retransmission PDSCH or to use a joint modulation piggybacking method.For a UE that is capable of different piggybacked methods, the AP may decide which piggybacked method to use based on the number of bits being carried in the piggybacked data. For example, if the piggybacked data is small, it may be easier to puncture a few REs in the pre-emptive retransmission PDSCH rather than superimposed the onto it. On the other hand, if the piggybacked data is similar to that of the pre-emptive retransmission PDSCH, then it may be more effective to superimposed the data or use joint modulation. In some arrangements of embodiments of the present technique, the AP indicates the code used to CDMthe piggybacked data with the pre-emptive retransmission PDSCH, for example in the DL Grant thatschedules either the piggybacked data or the pre-emptive retransmission PDSCH. In other words, theinfrastructure equipment may be configured to transmit, to the first communications device and / or the oneor more target communications devices, an indication of a code used for the code division multiplexingperformed on the second downlink data and the retransmission of the first downlink data beforetransmission of the second downlink channel. Here, a DMRS port indication can be used for such anindication. In some arrangements of embodiments of the present technique, the UE indicates its capability in decoding piggyback information. In other words, the infrastructure equipment may be configured toreceive, from the one or more target communications devices (e.g. as the piggybacking indicator), anindication of capability of the one or more target communications devices to process downlinktransmissions that are piggybacked onto other downlink transmissions. For example, the UE may indicate that it can perform SIC, or for a less advanced UE, it may indicate that it can only read punctured / rate matched piggybacked information.Figure 16 shows a flow diagram illustrating an example process of communications in a communicationssystem in accordance with embodiments of the present technique. The process shown by Figure 16 isspecifically a method of operating an infrastructure equipment (e.g. an AP such as a gNB) forming part ofa wireless communications network configured to transmit signals to and / or to receive signals from aplurality of communications devices (e.g. UEs). The method begins in step S1. The method comprises, in step S2, transmitting, to a first of the plurality of communications devices, a first downlink channel comprising first downlink data. In step S3, the process comprises transmitting, to the first communications device before feedback is received from the first communications device in response to the first downlink channel, a second downlink channel, wherein the second downlink channel comprises second downlink data piggybacked onto a retransmission of the first downlink data to the first communications device. Here, the second downlink data is for receipt by one or more target communications devices, the one or more target communicationsdevices being either the first communications device or one or more others of the plurality ofcommunications devices, and wherein the first communications device and the one or more othercommunications devices each form part of a proximity group of a subnetwork of the wirelesscommunications network, the subnetwork comprising at least the first communications device, the one or more other communications devices, and the infrastructure equipment. The process ends in step S4.Those skilled in the art would appreciate that the method shown by Figure 16 may be adapted inaccordance with embodiments of the present technique. For example, other intermediate steps may beincluded in such a method, or the steps may be performed in any logical order. Though embodiments ofthe present technique have been described largely by way of the example communications system shownin Figure 9, and further by way of the implementation examples shown in Figures 10 to 15, it would beclear to those skilled in the art that they could be equally applied to other systems to those described herein, provided that these are within the scope of the claims. Those skilled in the art would further appreciate that such infrastructure equipment and / or communications devices as herein defined may be further defined in accordance with the various arrangements and embodiments discussed in the preceding paragraphs. It would be further appreciated by those skilled in the art that such infrastructure equipment and communications devices as herein defined and described may form part of communications systems other than those defined by the present disclosure, provided that these are within the scope of the claims.

[0002] The following numbered paragraphs provide further example aspects and features of the present technique:Paragraph 1. A method of operating an infrastructure equipment forming part of a wirelesscommunications network configured to transmit signals to and / or to receive signals from a plurality of communications devices, the method comprising transmitting, to a first of the plurality of communications devices, a first downlink channel comprising first downlink data, and transmitting, to the first communications device before feedback is received from the first communications device in response to the first downlink channel, a second downlink channel, wherein the second downlink channel comprises second downlink data piggybacked onto a retransmission of the first downlink data to the first communications device, wherein the second downlink data is for receipt by one or more target communications devices, the one or more target communications devices being either the first communications device or one or more others of the plurality of communications devices, and wherein the first communications device and the one or more other communications devices each form part of a proximity group of a subnetwork of the wireless communications network, the subnetwork comprising at least the first communications device, the one or more other communications devices, and the infrastructure equipment.Paragraph 2. A method according to Paragraph 1, comprisingreceiving, from the one or more target communications devices, a piggybacking indicator,wherein the piggybacking indicator indicates whether the one or more target communications devices are able to receive the second downlink data when it is piggybacked onto the retransmission of the first downlink data, performing the piggybacking of the second downlink data onto the retransmission of the first downlink data if the piggybacking indicator indicates that the one or more target communications devices are able to receive the second downlink data when it is piggybacked onto the retransmission of the first downlink data.Paragraph 3. A method according to Paragraph 2, wherein the piggybacking indicator comprises acapability of the one or more target communications devices to process downlink transmissions that are piggybacked onto other downlink transmissions.Paragraph 4. A method according to Paragraph 2 or Paragraph 3, wherein the piggybacking indicatorcomprises a maximum piggybacked modulation and coding scheme, MCS, that, if the second downlink data had been transmitted in accordance with the maximum piggybacked MCS, the one or more target communications devices would have been able to successfully receive the second downlink data piggybacked onto the retransmission of the first downlink data within the second downlink channel in accordance with a predefined error rate.Paragraph 5. A method according to any of Paragraphs 2 to 4, wherein the piggybacking indicatorcomprises a maximum MCS that, if the second downlink data had been transmitted in accordance with the maximum MCS, the one or more target communications devices would have been able to successfully receive the second downlink data in accordance with a predefined error rate.Paragraph 6. A method according to any of Paragraphs 2 to 5, wherein the piggybacking indicatorcomprises a channel quality indicator, CQI, index indicating an MCS.Paragraph 7. A method according to any of Paragraphs 2 to 6, wherein the piggybacking indicatorcomprises an acknowledgement feedback signal transmitted by the one or more target communications devices to the infrastructure equipment in response to a previous downlink channel transmitted by the infrastructure equipment to the one or more target communications devices.Paragraph 8. A method according to Paragraph 7, wherein the acknowledgement feedback signalcomprises an indication of a level of difficulty of decoding of the previous downlink channel by the one or more target communications devices.Paragraph 9. A method according to any of Paragraphs 1 to 8, comprisingperforming the piggybacking of the second downlink data onto the retransmission of the first downlink data by adding the second downlink data to a subset of a set of downlink resources scheduled for the transmission of the second downlink channel.Paragraph 10. A method according to any of Paragraphs 1 to 9, comprisingperforming the piggybacking of the second downlink data onto the retransmission of the first downlink data by superimposing the second downlink data onto the first downlink data within a set of downlink resources scheduled for the transmission of the second downlink channel.Paragraph 11. A method according to Paragraph 10, wherein the superimposing the second downlinkdata onto the set of downlink resources scheduled for the retransmission of the first downlink datacomprises the second downlink data and the retransmission of the first downlink data being code divisionmultiplexed together before transmission of the second downlink channel.Paragraph 12. A method according to Paragraph 11, comprisingtransmitting, to the first communications device and / or the one or more target communications devices, an indication of a code used for the code division multiplexing performed on the seconddownlink data and the retransmission of the first downlink data before transmission of the seconddownlink channel.Paragraph 13. A method according to any of Paragraphs 10 to 12, wherein the superimposing thesecond downlink data onto the set of downlink resources scheduled for the retransmission of the firstdownlink data comprises the second downlink data and the retransmission of the first downlink databeing spatially multiplexed together before transmission of the second downlink channel.Paragraph 14. A method according to any of Paragraphs 10 to 13, wherein the superimposing thesecond downlink data onto the set of downlink resources scheduled for the retransmission of the first downlink data comprises the second downlink data and the retransmission of the first downlink data being jointly modulated before transmission of the second downlink channel.Paragraph 15. A method according to any of Paragraphs 10 to 14, wherein the transmitting the seconddownlink channel comprises transmitting the second downlink channel without performing multiplexing on the second downlink data and the retransmission of the first downlink data after performing the piggybacking.Paragraph 16. A method according to any of Paragraphs 1 to 15, comprisingtransmitting, to the one or more target communications devices, first downlink control information, DCI, wherein the first DCI schedules the transmission of the second downlink data within the second downlink channel, wherein the first DCI indicates that the second downlink data is piggybacked onto the retransmission of the first downlink data.Paragraph 17. A method according to Paragraph 16, wherein the first DCI comprises an indication ofhow the second downlink data is piggybacked onto the retransmission of the first downlink data.Paragraph 18. A method according to any of Paragraphs 1 to 17, comprisingtransmitting, to the first communications device, a second DCI which schedules the retransmission of the first downlink data within the second downlink channel, wherein the second DCI indicates that the second downlink data is piggybacked onto the retransmission of the first downlink data.Paragraph 19. A method according to Paragraph 18, wherein the second DCI comprises an indication ofhow the second downlink data is piggybacked onto the retransmission of the first downlink data.Paragraph 20. A method according to any of Paragraphs 1 to 19, comprisingtransmitting, to the first communications device, a second DCI which schedules the retransmission of the first downlink data within the second downlink channel, and transmitting, to one or more communication devices of the proximity group, a third DCI which indicates that the second downlink data is piggybacked onto the retransmission of the first downlink data.Paragraph 21. A method according to any of Paragraphs 1 to 20, comprising transmitting, to the first communications device and / or the one or more target communications devices, radio resource control, RRC, signalling, wherein the RRC signalling comprises an indication of how the second downlink data is piggybacked onto the retransmission of the first downlink data.Paragraph 22. An infrastructure equipment forming part of a wireless communications network, theinfrastructure equipment comprising transceiver circuitry configured to transmit signals to and / or to receive signals from a communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a first of the plurality of communications devices, a first downlink channel comprising first downlink data, and to transmit, to the first communications device before feedback is received from the first communications device in response to the first downlink channel, a second downlink channel, wherein the second downlink channel comprises second downlink data piggybacked onto a retransmission of the first downlink data to the first communications device, wherein the second downlink data is for receipt by one or more target communications devices, the one or more target communications devices being either the first communications device or one or more others of the plurality of communications devices, and wherein the first communications device and the one or more other communications devices each form part of a proximity group of a subnetwork of the wireless communications network, the subnetwork comprising at least the first communications device, the one or more other communications devices, and the infrastructure equipment.Paragraph 23. Circuitry for an infrastructure equipment forming part of a wireless communicationsnetwork, the circuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals from a communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a first of the plurality of communications devices, a first downlink channel comprising first downlink data, and to transmit, to the first communications device before feedback is received from the first communications device in response to the first downlink channel, a second downlink channel, wherein the second downlink channel comprises second downlink data piggybacked onto a retransmission of the first downlink data to the first communications device, wherein the second downlink data is for receipt by one or more target communications devices, the one or more target communications devices being either the first communications device or one or more others of the plurality of communications devices, and wherein the first communications device and the one or more other communications devices each form part of a proximity group of a subnetwork of the wireless communications network, the subnetwork comprising at least the first communications device, the one or more other communications devices, and the infrastructure equipment.Paragraph 24. A method of operating a communications device configured to transmit signals to and / orto receive signals from a wireless communications network, the method comprising receiving, from an infrastructure equipment of the wireless communications network, a second downlink channel, wherein the second downlink channel comprises second downlink data piggybacked onto a retransmission of first downlink data, the first downlink data having been received by either the communications device or a second communications device within a first downlink channel, and the second downlink channel being received by the communications device before feedback is transmitted by the either the communications device or the second communications device in response to the first downlink channel, wherein the communications device and the second communications device each form part of a proximity group of a subnetwork of the wireless communications network, the subnetwork comprising at least the communications device, the second communications device, and the infrastructure equipment.Paragraph 25. A method according to Paragraph 24, comprisingtransmitting, to the infrastructure equipment, a piggybacking indicator, wherein the piggybackingindicator indicates whether the communications device is able to receive the second downlink data whenit is piggybacked onto the retransmission of the first downlink data.Paragraph 26. A method according to Paragraph 25, wherein the piggybacking indicator comprises acapability of the communications device to process downlink transmissions that are piggybacked onto other downlink transmissions.Paragraph 27. A method according to Paragraph 25 or Paragraph 26, wherein the piggybackingindicator comprises a maximum piggybacked modulation and coding scheme, MCS, that, if the second downlink data had been transmitted in accordance with the maximum piggybacked MCS, the communications device would have been able to successfully receive the second downlink data piggybacked onto the retransmission of the first downlink data within the second downlink channel in accordance with a predefined error rate.Paragraph 28. A method according to any of Paragraphs 25 to 27, wherein the piggybacking indicatorcomprises a maximum MCS that, if the second downlink data had been transmitted in accordance with the maximum MCS, the communications device would have been able to successfully receive the second downlink data in accordance with a predefined error rate.Paragraph 29. A method according to any of Paragraphs 25 to 28, wherein the piggybacking indicatorcomprises a channel quality indicator, CQI, index indicating an MCS.Paragraph 30. A method according to any of Paragraphs 25 to 29, wherein the piggybacking indicatorcomprises an acknowledgement feedback signal transmitted by the communications device to the infrastructure equipment in response to a previous downlink channel received by the communications device from the infrastructure equipment.Paragraph 31. A method according to Paragraph 30, wherein the acknowledgement feedback signalcomprises an indication of a level of difficulty of decoding of the previous downlink channel by the communications device.Paragraph 32. A method according to any of Paragraphs 24 to 31, comprisingreceiving the second downlink data within a subset of a set of downlink resources of the second downlink channel.Paragraph 33. A method according to any of Paragraphs 24 to 32, comprisingreceiving the second downlink data within the second downlink channel, wherein the second downlink data is superimposed onto the first downlink data within a set of downlink resources of the second downlink channel.Paragraph 34. A method according to Paragraph 33, comprisingreceiving, from the infrastructure equipment, an indication of a code used for code division multiplexing performed by the infrastructure equipment on the second downlink data and the retransmission of the first downlink data before transmission of the second downlink channel by the infrastructure equipment.Paragraph 35. A method according to any of Paragraphs 24 to 34, comprisingreceiving, from the infrastructure equipment, downlink control information, DCI, wherein the DCI schedules the transmission of the second downlink data within the second downlink channel, wherein the DCI indicates that the second downlink data is piggybacked onto the retransmission of the first downlink data.Paragraph 36. A method according to Paragraph 35, wherein the DCI comprises an indication of howthe second downlink data is piggybacked onto the retransmission of the first downlink data.Paragraph 37. A method according to Paragraph 35 or Paragraph 36, wherein the DCI is a groupcommon DCI which is also receivable by one or more other communications devices in the proximity group.Paragraph 38. A method according to any of Paragraphs 24 to 37, comprising receiving, from the infrastructure equipment, radio resource control, RRC, signalling, wherein the RRC signalling comprises an indication of how the second downlink data is piggybacked onto the retransmission of the first downlink data.Paragraph 39. A communications device comprisingtransceiver circuitry configured to transmit signals to and / or to receive signals from a wireless communications network, and controller circuitry configured in combination with the transceiver circuitry to receive, from an infrastructure equipment of the wireless communications network, a second downlink channel, wherein the second downlink channel comprises second downlink data piggybackedonto a retransmission of first downlink data, the first downlink data having been received by either thecommunications device or a second communications device within a first downlink channel, and the second downlink channel being received by the communications device before feedback is transmitted by the either the communications device or the second communications device in response to the first downlink channel, wherein the communications device and the second communications device each form part of a proximity group of a subnetwork of the wireless communications network, the subnetwork comprising at least the communications device, the second communications device, and the infrastructure equipment.Paragraph 40. Circuitry for a communications device, the circuitry comprisingtransceiver circuitry configured to transmit signals to and / or to receive signals from a wireless communications network, and controller circuitry configured in combination with the transceiver circuitry to receive, from an infrastructure equipment of the wireless communications network, a second downlink channel, wherein the second downlink channel comprises second downlink data piggybacked onto a retransmission of first downlink data, the first downlink data having been received by either the transceiver circuitry or a second communications device within a first downlink channel, and the second downlink channel being received by the transceiver circuitry before feedback is transmitted by the either the transceiver circuitry or the second communications device in response to the first downlink channel, wherein the communications device and the second communications device each form part of a proximity group of a subnetwork of the wireless communications network, the subnetwork comprising at least the communications device, the second communications device, and the infrastructure equipment.Paragraph 41. A wireless communications system comprising an infrastructure equipment according toParagraph 22 and a communications device according to Paragraph 39.Paragraph 42. A computer program comprising instructions which, when loaded onto a computer, causethe computer to perform a method according to any of Paragraphs 1 to 21 or Paragraphs 24 to 38.Paragraph 43. A non-transitory computer-readable storage medium storing a computer programaccording to Paragraph 42. It will be appreciated that the above description for clarity has described embodiments with reference to different functional units, circuitry and / or processors. However, it will be apparent that any suitable distribution of functionality between different functional units, circuitry and / or processors may be used without detracting from the embodiments. Described embodiments may be implemented in any suitable form including hardware, software, firmware or any combination of these. Described embodiments may optionally be implemented at least partly as computer software running on one or more data processors and / or digital signal processors. The elements and components of any embodiment may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of unitsor as part of other functional units. As such, the disclosed embodiments may be implemented in a singleunit or may be physically and functionally distributed between different units, circuitry and / or processors. Although the present disclosure has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in any manner suitable to implement the technique.

[0003] References[1] TR 38.913, “Study on Scenarios and Requirements for Next Generation Access Technologies(Release 14)”, third Generation Partnership Project, v14.3.0, August 2017.[2] RP-190726, “Physical layer enhancements for NR ultra-reliable and low latency communication(URLLC)”, Huawei, HiSilicon, RAN#83, March 2019.[3] RP-201310, “Revised WID: Enhanced Industrial Internet of Things (IoT) and ultra-reliable andlow latency communication (URLLC) support for NR,” Nokia, Nokia Shanghai Bell, RAN#88e, July 2020.[4] European Patent Application No. EP23181917.8.[5] European Patent Application No. EP24152458.6.

[0004] ANNEX 1 Numerical Results An evaluation of the full behavior of the proposed piggyback technique requires substantial system simulations, across a variety of scenarios and use cases. Herein, the results of a very limited study of thetechnique are provided. While the setup used to produce such results is grossly delineated compared withwhat would be required for a comprehensive study, it is argued that such a setup captures the coreproperties required for an evaluation. As such, it suffices for demonstrating a definite technical effect.The piggybacked method adopted in this study is the one illustrated in Figure 14 – i.e. involving thesuperimposing of the piggybacked data onto the pre-emptive retransmission PDSCH. It is assumed thatthe data symbols ^^ are 16QAM modulation, while symbols ^^ are QPSK modulated. That is, 16-QAMdata is transmitted as a pre-emptive HARQ and QPSK to the piggybacked UE. To fulfill an overall power constraint at the gNB, constraints ^|^^|^ = ^|^^|^ = 1 are imposed and the transmitted signal isformed by a linear combination of ^^ and ^^ as ^^ = √^^^ + √1 − ^^^; the parameter ^ balances powerbetween the HARQ and the piggyback data transmissions and will be subsequently optimized. The received signals at the two UEs read, respectively, where: ^^^^^^^is received at the UE to which the pre-emptive HARQ is intended, and ^^^^at the UE to receive the piggybacked data. ^The two quantities ^^^^^^^ and ^^^^^ denote the average SNRs at the two UEs, respectively.^ ℎ^^^^ ^ and ℎ^^^are independent zero-mean circularly symmetric complex Gaussian random variables with unit variance. These represent the small scale fading. ^^^^^^^and ^^^^are independent zero-mean circularly symmetric complex Gaussian random noise variables with unit variance.For the piggyback method to be meaningful, it is apparent that the ability for the two UEs to extract information from their received signals must exceed what is possible by time-sharing between pre- emptive HARQ transmissions and data transmissions. To measure said ability, many metrics can beconsidered, and ultimately only system simulations can provide the full answer. One metric thatrepresents the behavior of practical receivers very well is the BICM-capacity, which the one chosen here. The BICM capacity for the HARQ UE is computed as follows. As ^^are 16-QAM symbols, eachsymbol is represented by four bits (^^,^, ^^,^, ^^,^, ^^,^). (These are not the ^^ bits shown in Figure 14).Given the received signal ^^^^^^ , one may compute the LLR values (for ℓ = 1,2,3,4), The notation ^ℓ(^) fetches the ℓ:th bit of a symbol ^, i.e., ^ℓ(^^) = ^^,ℓ.The BICM capacity is, by definition, computed as where ^(⋅;⋅) is the mutual information operator and is straightforward to compute via Monte Carlomethods (for the reader skilled in the art), provided that a large number of samples is at hand.Similarly, for the piggyback UE, each symbol ^^ is specified from two bits (^^,^, ^^,^). LLRs may beproduced as and concluded by However, one should keep in mind that the rate is not always meaningful. That is, in case the pre- emptive HARQ is unnecessary, then the usefulness of the HARQ is null, and, consequently, the rate ^^^^^^^^^should not be accounted for in a performance evaluation. To that end, the variable ^^^^^is introduced, which measures the probability that a HARQ is needed. Thus, the expected usefulness of the HARQ transmission must be weighted by this quantity, resulting in the “good-put” metric. ^^^^^^^^^,^^ = ^^^^^^^^^^^^^^.In the following simulations, three different setups for the average SNRs have been tested, namely:^^^^^^^^, ^^^^^^ = (10,10), (10,7), (7,10) (in dBs). Further, ^^^^^ ∈ {1,0.7,0.5} has been evaluatedfor. The small-scale fading variables ℎ^^^^^and ℎ^^^have been generated as independent also across the index ^, which technically implies that all BICM capacities should be understood in an ergodic sense. Finally, each mutual information computation has been done with 10^channel realizations. The results are shown in Figures 17 to 19 for the three different SNR setups. Specifically, Figure 17 illustrates Trajectories of (^^^^^^^^^,^^ , ^ ^^^^^^ ) parameterized by ^ for different values of ^^^^^. The SNRvalues are ^^^^^^^^, ^^^^^^ = (10^^, 10^^), Figure 18 illustrates the same as Figure 17, but for SNRvalues ^^^^^^^^ , ^^^^^^ = (10^^, 7^^), while Figure 19 illustrates the same as Figure 17, but for SNRvalues ^^^^^^^^ , ^^^^^^ = (7^^, 10^^).All three plots display very similar structures, so it suffices to discuss Figure 17. In such a figure, thetrajectory of (^^^^^^^^^,^^ , ^ ^^^^^^ ) is plotted, parameterized by the power balance parameter ^. The dashedcurves show level curves for constant values of ^^^^^^^^^,^^ + ^ ^^^^^^ . To optimize performance, one may,e.g., operate at the point which reaches the outermost level curve. For cases in which the pre-emptiveHARQ is always needed, i.e., ^^^^^ = 1, it is observed that the optimal strategy is always to abandonpiggyback information and, consequently, set ^ = 1. However, as the likelihood of the HARQ beingmeaningful reduces, the picture changes. For example, with ^^^^^ = 0.7 it appears optimal to set ^ ≈0.8. Ultimately, the system designer needs to make a choice on which operating point they desire. But it stands clear that the piggyback method is always superior, in the sum-BICM-capacity sense, whenever^^^^^ < 1 compared with time sharing between HARQ and data transmissions.Finally, it is noted that the curves display that the worst operating point is that of ^ = 0.5, i.e., allocatingequal power between HARQ and data. This observation appears to hold true for all values of ^^^^^andSNRs. This is an effect of the symbol constellations – which have been taken as standard 16QAM andQPSK constellations. Interestingly, and going beyond what is presented herein, it has been observed thata rotation of the QPSK constellation compared with the 16QAM one reduces the rates. Theseobservations pave the way for future work on constellation designs for piggybacked HARQ transmissions.

Claims

CLAIMS What is claimed is:

1. A method of operating an infrastructure equipment forming part of a wireless communicationsnetwork configured to transmit signals to and / or to receive signals from a plurality of communications devices, the method comprising transmitting, to a first of the plurality of communications devices, a first downlink channelcomprising first downlink data, andtransmitting, to the first communications device before feedback is received from the firstcommunications device in response to the first downlink channel, a second downlink channel, whereinthe second downlink channel comprises second downlink data piggybacked onto a retransmission of thefirst downlink data to the first communications device,wherein the second downlink data is for receipt by one or more target communications devices,the one or more target communications devices being either the first communications device or one ormore others of the plurality of communications devices, and wherein the first communications device andthe one or more other communications devices each form part of a proximity group of a subnetwork ofthe wireless communications network, the subnetwork comprising at least the first communications device, the one or more other communications devices, and the infrastructure equipment.

2. A method according to Claim 1, comprisingreceiving, from the one or more target communications devices, a piggybacking indicator,wherein the piggybacking indicator indicates whether the one or more target communications devices areable to receive the second downlink data when it is piggybacked onto the retransmission of the first downlink data, performing the piggybacking of the second downlink data onto the retransmission of the firstdownlink data if the piggybacking indicator indicates that the one or more target communications devicesare able to receive the second downlink data when it is piggybacked onto the retransmission of the firstdownlink data.

3. A method according to Claim 2, wherein the piggybacking indicator comprises a capability of theone or more target communications devices to process downlink transmissions that are piggybacked ontoother downlink transmissions.

4. A method according to Claim 2, wherein the piggybacking indicator comprises a maximumpiggybacked modulation and coding scheme, MCS, that, if the second downlink data had beentransmitted in accordance with the maximum piggybacked MCS, the one or more target communicationsdevices would have been able to successfully receive the second downlink data piggybacked onto theretransmission of the first downlink data within the second downlink channel in accordance with apredefined error rate.

5. A method according to Claim 2, wherein the piggybacking indicator comprises a maximum MCSthat, if the second downlink data had been transmitted in accordance with the maximum MCS, the one ormore target communications devices would have been able to successfully receive the second downlinkdata in accordance with a predefined error rate.

6. A method according to Claim 2, wherein the piggybacking indicator comprises a channel qualityindicator, CQI, index indicating an MCS.

7. A method according to Claim 2, wherein the piggybacking indicator comprises anacknowledgement feedback signal transmitted by the one or more target communications devices to theinfrastructure equipment in response to a previous downlink channel transmitted by the infrastructureequipment to the one or more target communications devices.

8. A method according to Claim 7, wherein the acknowledgement feedback signal comprises anindication of a level of difficulty of decoding of the previous downlink channel by the one or more targetcommunications devices.

9. A method according to Claim 1, comprisingperforming the piggybacking of the second downlink data onto the retransmission of the firstdownlink data by adding the second downlink data to a subset of a set of downlink resources scheduledfor the transmission of the second downlink channel.

10. A method according to Claim 1, comprisingperforming the piggybacking of the second downlink data onto the retransmission of the firstdownlink data by superimposing the second downlink data onto the first downlink data within a set ofdownlink resources scheduled for the transmission of the second downlink channel.

11. A method according to Claim 10, wherein the superimposing the second downlink data onto theset of downlink resources scheduled for the retransmission of the first downlink data comprises the second downlink data and the retransmission of the first downlink data being code division multiplexedtogether before transmission of the second downlink channel.

12. A method according to Claim 11, comprisingtransmitting, to the first communications device and / or the one or more target communications devices, an indication of a code used for the code division multiplexing performed on the second downlink data and the retransmission of the first downlink data before transmission of the second downlink channel.

13. A method according to Claim 10, wherein the superimposing the second downlink data onto theset of downlink resources scheduled for the retransmission of the first downlink data comprises the second downlink data and the retransmission of the first downlink data being spatially multiplexed together before transmission of the second downlink channel.

14. A method according to Claim 10, wherein the superimposing the second downlink data onto theset of downlink resources scheduled for the retransmission of the first downlink data comprises the second downlink data and the retransmission of the first downlink data being jointly modulated before transmission of the second downlink channel.

15. A method according to Claim 10, wherein the transmitting the second downlink channelcomprises transmitting the second downlink channel without performing multiplexing on the second downlink data and the retransmission of the first downlink data after performing the piggybacking.

16. A method according to Claim 1, comprisingtransmitting, to the one or more target communications devices, first downlink controlinformation, DCI, wherein the first DCI schedules the transmission of the second downlink data withinthe second downlink channel, wherein the first DCI indicates that the second downlink data ispiggybacked onto the retransmission of the first downlink data.

17. A method according to Claim 16, wherein the first DCI comprises an indication of how thesecond downlink data is piggybacked onto the retransmission of the first downlink data.

18. A method according to Claim 1, comprisingtransmitting, to the first communications device, a second DCI which schedules the retransmission of the first downlink data within the second downlink channel, wherein the second DCI indicates that the second downlink data is piggybacked onto the retransmission of the first downlink data.

19. A method according to Claim 18, wherein the second DCI comprises an indication of how thesecond downlink data is piggybacked onto the retransmission of the first downlink data.

20. A method according to Claim 1, comprisingtransmitting, to the first communications device, a second DCI which schedules the retransmission of the first downlink data within the second downlink channel, and transmitting, to one or more communication devices of the proximity group, a third DCI whichindicates that the second downlink data is piggybacked onto the retransmission of the first downlink data.

21. A method according to Claim 1, comprisingtransmitting, to the first communications device and / or the one or more target communicationsdevices, radio resource control, RRC, signalling, wherein the RRC signalling comprises an indication of how the second downlink data is piggybacked onto the retransmission of the first downlink data.

22. An infrastructure equipment forming part of a wireless communications network, theinfrastructure equipment comprising transceiver circuitry configured to transmit signals to and / or to receive signals from a communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a first of the plurality of communications devices, a first downlink channel comprising first downlink data, and to transmit, to the first communications device before feedback is received from the firstcommunications device in response to the first downlink channel, a second downlink channel, whereinthe second downlink channel comprises second downlink data piggybacked onto a retransmission of thefirst downlink data to the first communications device,wherein the second downlink data is for receipt by one or more target communications devices,the one or more target communications devices being either the first communications device or one ormore others of the plurality of communications devices, and wherein the first communications device andthe one or more other communications devices each form part of a proximity group of a subnetwork ofthe wireless communications network, the subnetwork comprising at least the first communications device, the one or more other communications devices, and the infrastructure equipment.

23. Circuitry for an infrastructure equipment forming part of a wireless communications network, thecircuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals from acommunications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to a first of the plurality of communications devices, a first downlink channel comprising first downlink data, andto transmit, to the first communications device before feedback is received from the firstcommunications device in response to the first downlink channel, a second downlink channel, whereinthe second downlink channel comprises second downlink data piggybacked onto a retransmission of thefirst downlink data to the first communications device,wherein the second downlink data is for receipt by one or more target communications devices,the one or more target communications devices being either the first communications device or one ormore others of the plurality of communications devices, and wherein the first communications device andthe one or more other communications devices each form part of a proximity group of a subnetwork ofthe wireless communications network, the subnetwork comprising at least the first communications device, the one or more other communications devices, and the infrastructure equipment.

24. A method of operating a communications device configured to transmit signals to and / or toreceive signals from a wireless communications network, the method comprising receiving, from an infrastructure equipment of the wireless communications network, a seconddownlink channel, wherein the second downlink channel comprises second downlink data piggybackedonto a retransmission of first downlink data, the first downlink data having been received by either thecommunications device or a second communications device within a first downlink channel, and thesecond downlink channel being received by the communications device before feedback is transmitted bythe either the communications device or the second communications device in response to the firstdownlink channel, wherein the communications device and the second communications device each form part of a proximity group of a subnetwork of the wireless communications network, the subnetwork comprising at least the communications device, the second communications device, and the infrastructure equipment.

25. A method according to Claim 24, comprisingtransmitting, to the infrastructure equipment, a piggybacking indicator, wherein the piggybacking indicator indicates whether the communications device is able to receive the second downlink data when it is piggybacked onto the retransmission of the first downlink data.

26. A method according to Claim 25, wherein the piggybacking indicator comprises a capability ofthe communications device to process downlink transmissions that are piggybacked onto other downlink transmissions.

27. A method according to Claim 25, wherein the piggybacking indicator comprises a maximumpiggybacked modulation and coding scheme, MCS, that, if the second downlink data had been transmitted in accordance with the maximum piggybacked MCS, the communications device would have been able to successfully receive the second downlink data piggybacked onto the retransmission of the first downlink data within the second downlink channel in accordance with a predefined error rate.

28. A method according to Claim 25, wherein the piggybacking indicator comprises a maximumMCS that, if the second downlink data had been transmitted in accordance with the maximum MCS, the communications device would have been able to successfully receive the second downlink data in accordance with a predefined error rate.

29. A method according to Claim 25, wherein the piggybacking indicator comprises a channel qualityindicator, CQI, index indicating an MCS.

30. A method according to Claim 25, wherein the piggybacking indicator comprises anacknowledgement feedback signal transmitted by the communications device to the infrastructureequipment in response to a previous downlink channel received by the communications device from the infrastructure equipment.

31. A method according to Claim 30, wherein the acknowledgement feedback signal comprises anindication of a level of difficulty of decoding of the previous downlink channel by the communications device.

32. A method according to Claim 24, comprisingreceiving the second downlink data within a subset of a set of downlink resources of the second downlink channel.

33. A method according to Claim 24, comprisingreceiving the second downlink data within the second downlink channel, wherein the seconddownlink data is superimposed onto the first downlink data within a set of downlink resources of thesecond downlink channel.

34. A method according to Claim 33, comprisingreceiving, from the infrastructure equipment, an indication of a code used for code division multiplexing performed by the infrastructure equipment on the second downlink data and theretransmission of the first downlink data before transmission of the second downlink channel by theinfrastructure equipment.

35. A method according to Claim 24, comprisingreceiving, from the infrastructure equipment, downlink control information, DCI, wherein the DCI schedules the transmission of the second downlink data within the second downlink channel, wherein the DCI indicates that the second downlink data is piggybacked onto the retransmission of the first downlink data.

36. A method according to Claim 35, wherein the DCI comprises an indication of how the seconddownlink data is piggybacked onto the retransmission of the first downlink data.

37. A method according to Claim 35, wherein the DCI is a group common DCI which is alsoreceivable by one or more other communications devices in the proximity group.

38. A method according to Claim 24, comprisingreceiving, from the infrastructure equipment, radio resource control, RRC, signalling, wherein the RRC signalling comprises an indication of how the second downlink data is piggybacked onto the retransmission of the first downlink data.

39. A communications device comprisingtransceiver circuitry configured to transmit signals to and / or to receive signals from a wireless communications network, and controller circuitry configured in combination with the transceiver circuitry to receive, from an infrastructure equipment of the wireless communications network, a seconddownlink channel, wherein the second downlink channel comprises second downlink data piggybackedonto a retransmission of first downlink data, the first downlink data having been received by either thecommunications device or a second communications device within a first downlink channel, and thesecond downlink channel being received by the communications device before feedback is transmitted bythe either the communications device or the second communications device in response to the firstdownlink channel, wherein the communications device and the second communications device each form part of a proximity group of a subnetwork of the wireless communications network, the subnetwork comprising at least the communications device, the second communications device, and the infrastructure equipment.

40. Circuitry for a communications device, the circuitry comprisingtransceiver circuitry configured to transmit signals to and / or to receive signals from a wireless communications network, and controller circuitry configured in combination with the transceiver circuitry to receive, from an infrastructure equipment of the wireless communications network, a seconddownlink channel, wherein the second downlink channel comprises second downlink data piggybackedonto a retransmission of first downlink data, the first downlink data having been received by either thetransceiver circuitry or a second communications device within a first downlink channel, and the seconddownlink channel being received by the transceiver circuitry before feedback is transmitted by the eitherthe transceiver circuitry or the second communications device in response to the first downlink channel,wherein the communications device and the second communications device each form part of a proximity group of a subnetwork of the wireless communications network, the subnetwork comprising at least the communications device, the second communications device, and the infrastructure equipment.

41. A wireless communications system comprising an infrastructure equipment according to Claim22 and a communications device according to Claim 39.

42. A computer program comprising instructions which, when loaded onto a computer, cause thecomputer to perform a method according to Claim 1 or Claim 24.

43. A non-transitory computer-readable storage medium storing a computer program according toClaim 42.

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