Methods, infrastructure equipment and core networks

Abstract

A method of operating an infrastructure equipment forming part of a radio access network is provided. The method comprises receiving, from a core network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, receiving, from the core network, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, discarding at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device, and transmitting, to the core network, a third indication of an amount of the discarded FEC data.

Description

[0001] METHODS, INFRASTRUCTURE EQUIPMENT, AND CORE NETWORKS

[0002] BACKGROUND

[0003] Field of Disclosure

[0004] The present disclosure relates to infrastructure equipment of a radio access network, core networks, and methods for the transmission of data by infrastructure equipment to terminal devices.

[0005] The present application claims the Paris Convention priority from United Kingdom patent application number GB2400500.1, filed on 12 January 2024, the contents of which are hereby incorporated by reference.

[0006] Description of Related Art

[0007] 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.

[0008] 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 where access to the networks is possible, is expected to continue to increase rapidly.

[0009] 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 resolution video displays, virtual reality headsets, extended Reality (XR) and so on. Some of these different types of devices may be deployed in very large numbers, for example low complexity devices for supporting the “The Internet of Things”, and may typically be associated with the transmissions of relatively small amounts of data with relatively high latency tolerance. 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 charactensed by data that should be transmitted through the network with low latency and high reliability. A single device type might also be associated with different traffic profiles / characteristics depending on the application(s) it is running. For example, different consideration 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).

[0010] 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.

[0011] One example of a new service is referred to as Ultra Reliable Low Latency Communications (URLLC) services which, as its name suggests, requires that a data unit or packet be communicated with a high reliability and with a low communications delay. Another example of a new service is extended Reality (XR), which may be provided by various user equipment such as wearable devices. XR combines real- world and virtual environments, incorporating aspects such as augmented reality (AR), mixed reality (MR), and virtual reality (VR), and thus requires high quality and minimised interaction delay. Services such as URLLC and XR therefore represent a challenging example for both LTE type communications systems and 5G / NR communications systems, as well as future generation communications systems.

[0012] 5G NR has continuously evolved and the current work plan includes 5G-NR-advanced in which some further enhancements are expected, especially to support new use-cases / scenarios with higher requirements. The desire to support these new use-cases and scenarios gives rise to new challenges for efficiently handling communications in wireless communications systems that need to be addressed.

[0013] SUMMARY OF THE DISCLOSURE

[0014] The present disclosure can help address or mitigate at least some of the issues discussed above.

[0015] Some embodiments of the present technique can provide a method of operating an infrastructure equipment forming part of a radio access network. The method comprises receiving, from a core network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, receiving, from the core network, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, discarding at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device, and transmitting, to the core network, a third indication of an amount of the discarded FEC data.

[0016] Such embodiments of the present technique, which, in addition to methods of operating infrastructure equipment, relate to methods of operating core network entities, to infrastructure equipment and core network entities, circuitry for infrastructure equipment and core network entities, wireless communications systems, computer programs, and computer-readable storage mediums, can allow for the more efficient and effective transmission of data by infrastructure equipment to terminal devices.

[0017] Respective aspects and features of the present disclosure are defined in the appended claims.

[0018] It is to be understood that both the foregoing general description and the following detailed descnption 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.

[0019] BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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 LTE-type wireless telecommunication system which may be configured to operate in accordance with certain embodiments of the present disclosure;

[0021] Figure 2 schematically represents some aspects of an NR-type wireless telecommunications system which may be configured to operate in accordance with certain embodiments of the present disclosure;

[0022] Figure 3 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;

[0023] Figure 4 is a schematic block diagram of an example wireless communications network which may be configured to operate in accordance with certain embodiments of the present disclosure;

[0024] Figure 5 is reproduced from [8], and illustrates a traffic model for extended Reality (XR);

[0025] Figure 6 shows a part schematic, part message flow diagram representation of a wireless communications system comprising a communications device and an infrastructure equipment in accordance with embodiments of the present technique;

[0026] Figure 7 shows a message flow diagram involving a user equipment, UE, radio access node, RAN, and vanous core network entities, which illustrates various example arrangements and aspects of embodiments of the present technique; and

[0027] Figure 8 shows a flow diagram illustrating an example process of communications in a communications system in accordance with embodiments of the present technique.

[0028] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Long Term Evolution Advanced Radio Access Technology (4G)

[0030] Figure 1 provides a schematic diagram illustrating some basic functionality of a mobile telecommunications network / system 6 operating generally in accordance with LTE principles, but which may also support other radio access technologies, and which may be adapted to implement embodiments of the disclosure as described herein. Various elements of Figure 1 and certain aspects of their respective modes of operation are well-known and defined in the relevant standards administered by the 3GPP body, and also described in many books on the subject, for example, Holma H. and Toskala A [1] . 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.

[0031] The network 6 includes a plurality of base stations 1 connected to a core network 2. Each base station provides a coverage area 3 (i.e., a cell) within which data can be communicated to and from communications devices 4. Although each base station 1 is shown in Figure 1 as a single entity, the skilled person will appreciate that some of the functions of the 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.

[0032] Data is transmitted from base stations 1 to communications devices 4 within their respective coverage areas 3 via a radio downlink (DL). Data is transmitted from communications devices 4 to the base stations 1 via a radio uplink (UL). The core network 2 routes data to and from the communications devices 4 via the respective base stations 1 and provides functions such as authentication, mobility management, charging and so on. Terminal devices may also be referred to as mobile stations, user equipment (UE), user terminal, mobile radio, communications device, and so forth. Services provided by the core network 2 may include connectivity to the internet or to external telephony services. The core network 2 may further track the location of the communications devices 4 so that it can efficiently contact (i.e., page) the communications devices 4 for transmitting downlink data towards the communications devices 4.

[0033] Base stations, which are an example of network infrastructure equipment, may also be referred to as transceiver stations, nodeBs, e-nodeBs, eNB, g-nodeBs, gNB 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 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.

[0034] New Radio Access Technology (5G)

[0035] An example configuration of a wireless communications network which uses some of the terminology proposed for and used in NR and 5G is shown in Figure 2. In Figure 2 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. 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 lOhas a coverage area as represented by a circle 12. As such, wireless communications devices 14 which are within the coverage area 12 of each of the TRPs 10 can transmit and receive signals to and from those 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 30.

[0036] The elements of the wireless access network shown in Figure 2 may operate in a similar way to corresponding elements of an LTE network as described with regard to the example of Figure 1. It will be appreciated that operational aspects of the telecommunications network represented in Figure 2, 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.

[0037] The TRPs 10 of Figure 2 may in part have a corresponding functionality to a base station or eNodeB of an LTE network. Similarly, the communications devices 14 may have a functionality corresponding to the UE devices 4 known for operation with an LTE network. It will be appreciated therefore that operational aspects of a new RAT network (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be different to those known from LTE or other known mobile telecommunications standards. However, it will also be appreciated that each of the core network component, base stations and communications devices of a new RAT network will be functionally similar to, respectively, the core network component, base stations and communications devices of an LTE wireless communications network.

[0038] In terms of broad top-level functionality, the core network 20 connected to the new RAT telecommunications system represented in Figure 2 may be broadly considered to correspond with the core network 2 represented in Figure 1, and the respective central units 40 and their associated distributed units / TRPs 10 may be broadly considered to provide functionality corresponding to the base stations 1 of Figure 1. The term network infrastructure equipment / access node may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may lie with the controlling node / central unit and / or the distributed units / TRPs. A communications device 14 is represented in Figure 2 within the coverage area of the first coverage area 12. This communications device 14 may thus exchange signalling with the first central unit 40 in the first coverage area 12 via one of the distributed units / TRPs 10 associated with the first coverage area 12.

[0039] It will further be appreciated that Figure 2 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.

[0040] 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 architectures shown in Figures 1 and 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 base station, such as an LTE-type base station 1 as shown in Figure 1 which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment may comprise a control unit / controlling node 40 and / or a TRP 10 of the kind shown in Figure 2 which is adapted to provide functionality in accordance with the principles described herein.

[0041] A more detailed diagram of some of the components of the network shown in Figure 2 is provided by Figure 3. In Figure 3, a TRP 10 as shown in Figure 2 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 more UEs 14 within a coverage area 12 formed by the TRP 10. As shown in Figure 3, an example UE 14 is shown to include 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 data to the wireless communications network via the wireless access interface formed by the TRP 10 and to receive downlink data as signals transmitted by the transmitter 30 and received by the receiver 48 in accordance with the conventional operation.

[0042] 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 3 as separate elements for ease of representation. However, it will be appreciated that the functionality of these elements can be provided in various different ways, for example using one or more suitably programmed programmable computer(s), or one or more suitably configured application-specific integrated circuit(s) / circuitry / chip(s) / chipset(s). As will be appreciated the infrastructure equipment / TRP / base station as well as the UE / communications device will in general comprise various other elements associated with its operating functionality.

[0043] As shown in Figure 3, 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.

[0044] The interface 46 between the DU 42 and the CU 40 is known as the F 1 interface which can be a physical or a logical interface. The Fl 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 Fl interface 46 from the DU 42 to the CU 40. The core network 20 is connected to the CU 40 via the N2 (also called NG-C) interface for carrying control data and via the N3 (also called NG-U) interface for carrying user data.

[0045] Figure 4 illustrates a communications network 51 which may be configured to operate in accordance with certain embodiments of the present disclosure, and in which the core network 20 (i .e. the core network 20 discussed with respect to Figures 2 and 3, for example) is shown in more detail. The communications network 51 of Figure 4 comprises a UE 14, an access node (AN) 10 which may in particular be a radio access node (RAN) such as a gNB, a core network 20, and an application function node (AF) 52. Here, as those skilled in the art would appreciate, the AF 52 controls applications though providing interaction between the application layer and various network functions and resources.

[0046] The core network 20 here may be a 5G / NR core network as specified by the 3GPP such as a 5GC and as referred to above with respect to Figure 2, for example. The core network 20 as shown in Figure 4 may comprise several core network nodes, in particular a policy control function and / or network exposure function node (PCF / NEF) 54 which control some aspects related to security and capacity, a session management function node (SMF) 55 that handles calls and sessions, an access and mobility management function node (AMF) 56 that provides access for the UE 14 and the AN / RAN 10, and / or a user plane function node (UPF) 53 which handles user data. The AF may, for example, interact with the NEF / PCT 54 and / or the UPF 53. Those skilled in the art would appreciate that the core network 20 may comprise other functions to those that are shown in Figure 4, which include but are not limited to: a unified data management function node (UDM), a network repository function node (NRF), a network slice selection function node (NSSF), and a charging function node (CHF), which allows charging functions to be provided to network functions.

[0047] Services Supported by NR Networks

[0048] Systems incorporating NR technology support a number of 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. A requirement for Ultra Reliable and Low Latency Communications (URLLC) services is that one transmission of a 32 byte packet is required to be transmitted from the radio protocol layer 2 / 3 SDU ingress point to the radio protocol layer 2 / 3 SDU egress point of the radio interface within 1 ms with a reliability of 1 - 10'5(99.999 %) or higher (99.9999 %) [2], 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.

[0049] Enhanced URLLC (e URLLC) [3] [4] specifies features that require high reliability and low latency, such as factory automation, transport industry, electrical power distribution, etc. It should be appreciated that the Uplink Control Information (UCI) for URLLC and eMBB will have different requirements.

[0050] Another such service incorporating NR technology is 5G NR in Unlicensed Spectrum (NR-U) [5], which enable devices to make use of shared and unlicensed spectrum bandwidth. Such features as Listen Before Talk (LBT), as specified by [5], is incorporated into the NR frame structure for NR-U operation in unlicensed bands. extended Reality (XR), which covers a number of different types of application such as as augmented reality (AR), mixed reality (MR), and virtual reality (VR), and cloud gaming (CG), refers generally to various types of augmented, virtual, and mixed environments, where human-to-machine and human-to- human communications are performed with the assistance of handheld and wearable end user devices (UEs) . XR applications are considered important for NR Rel- 18 and beyond (also known as 5G Advanced) [6],

[0051] XR applications may require both a relatively high data rates and low latency. As 5G NR was not designed to support the combination of the aforementioned requirements, XR applications may not be supported optimally in 5G NR networks and user experience may suffer because the required data rate / latency may not be reached and UE power consumption may be high. XR applications may have the unique characteristic that the associated traffic pattern is deterministic (i.e., have a certain periodicity and certain number of traffic flows). There may be further relevant other applications with multiple data streams having different characteristics, like factory automation, remote machine operation, and unmanned aerial vehicle (UAV) operation, or applications requiring a differentiation between video and audio.

[0052] XR traffic is rich in video, especially in the downlink, with a typical frame rate of 60 Hz [7], which leads to a data transmission with non-integer periodicity in NR, i.e. the periodicity is not an integer number of subframes and in this example, the periodicity is 16.67 ms. Due to varying frame encoding delay and network transfer time, the packet arrival at the gNB may experience random jitter. The non-integer and jitter characteristics of XR traffic is known as quasi-periodic traffic. In addition to jitter, the packet size also varies within a range; that is the packet size in each period is random. The jitter and random packet size of UL traffic is illustrated in Figure 5, which is based on a similar figure (figure 5. 1.1-1) in [8],

[0053] Figure 5 illustrates a single stream traffic model for XR. A first packet k 61 is transmitted, representing Internet Protocol (IP) packets belonging to video frame k. At a later point in time - which, on average, is the inverse of the frame generation rate (i.e., I / fps) as denoted by arrow 65 - a second packet k+1 62 is transmitted, representing IP packets belonging to video frame k+1. The variable packet size which follows a probability distribution is shown by arrow 63, while the variable jitter which also follows a probability distribution is denoted by arrow 64. Error Correction in NR

[0054] As with wireless communication in previous generations of telecommunications networks, error correction codes are used in 5G / NR in order to improve performance by enabling data to be transmitted and received with fewer errors. Typically, these error correction codes involve forward error correction (FEC), where further parity bits or redundancy built into the encoded user data is used to reduce the likelihood of errors in transmission through the detection and / or correction of errors during the actual reception and decoding process. The FEC bits can be transmitted along with the data, or in response to requests for those FEC bits, for example, upon detection of an error at the receiver.

[0055] In 5G / NR systems, Hybrid Automatic Repeat Request (HARQ) processes are typically used to control errors, where such HARQ processes involve the use of both FEC codes and automatic repeat request procedures, in which a negative HARQ acknowledgement, known as a HARQ-NACK, indicates that the receiver (i.e. a UE) requires erroneous data to be re-transmitted. A Physical Downlink Shared Channel (PDSCH) carrying user data is transmitted to a UE by an gNB or the like using HARQ transmission, where for a PDSCH ending in slot n, the corresponding Physical Uplink Control Channel (PUCCH) carrying the HARQ-ACK is transmitted in slot n+Ki. Here, in Dynamic Grant PDSCH, the value of Ki is indicated in the field "PltSCH-to-HARQ feedhack timing indicator" of the DL Grant (carried by DCI Format 1 0, DCI Format 1 1 or DCI Format 1_2). Multiple (different) PDSCHs can point to the same slot for transmission of their respective HARQ-ACKs, and these HARQ-ACKs (in the same slot) are multiplexed into a single PUCCH. Hence, a PUCCH can contain multiple HARQ-ACKs for multiple PDSCHs.

[0056] Forward Error Correction (FEC) in XR

[0057] In downlink data for XR Rel-19 it is proposed in [9], for example, that the FEC bits from the application layer may be discarded by the RAN when it is detected by the RAN that the uncoded data (i.e. the user data that is transmitted without transmitting the associated FEC bits) is received by the UE without any errors. Such a possibility of discarding FEC bits at the RAN is also part of the proposed study items for XR.

[0058] It is well established that data can be discarded in the RAN when the network is congested or L2 buffers in the network are overflowing or at risk of overflow, and therefore the discardTimer for the data packet has expired. Section 5.3 of

[0010] describes how the discardTimer expiry results in the discarding of service data units (SDUs) at the Packet Data Convergence Protocol (PDCP) layer by the transmitting PDCP entity.

[0059] In general, the amount of data transmitted in the downlink by the RAN to the UE is not signalled from RAN to the core network, because the core network only knows how much data there is to be transmitted, having itself provided this to the RAN along the with associated FEC data. There is however one case in which such an amount of downlink data is signalled by the RAN to the core network. As can be understood from section 5.12.2 of

[0011] , the data usage is signalled for the Secondary RAT in dual connectivity scenarios. When NG-RAN (i.e. the 5G access network) is deployed in a dual connectivity configuration, the home public land mobile network (HPLMN) or visited public land mobile network (VPLMN) operator may wish to record the data volume sent and received on the Secondary RAT (which may be LTE or NR, for example). The signalling sent from the RAN to the SMF in this case is specified in section 4.21 of

[0012] section 4.21, entitled 'Secondary RAT Usage Data Reporting Procedure" .

[0060] According to SA4 the UE may treat any missing PDUs as a degraded connection, and therefore request lower quality of the media stream in order to ensure that PDUs can be successfully received. However, there are media protocols that separate the payload data and error correction (FEC) data so the receiving side does not need to parse the FEC data until there is something missing in the payload that requires the FEC data to identified and used to correct the payload. A technical problem with this however is that the core network does not know whether or not the UE will ignore it if FEC packages are missing so therefore the current standard is that the core network should never allow the discarding of any FEC packages even if the payload data is delivered correctly, to avoid the knock-on effect of a degradation of the quality of the media stream.

[0061] Another related issue is that charging of DL data is based on the amount of data sent from the UPF to the RAN. The amount of data sent from the UPF is signalled to the SMF which forwards it to the CHF. The CHF is responsible for the charging in the 3GPP network, as explained in

[0013] , where the charging architecture is specified. However, since FEC data may be discarded by the RAN under certain conditions and in respect of certain applications such as XR, as described above, the signalled amount of data from the UPF to the SMF and to the CHF may not be an accurate representation of the actual data transmitted, leading to inaccurate or unfair charging.

[0062] Embodiments of the present technique therefore provide solutions to such problems, which therefore enable the discarding of FEC data under certain conditions to enable more efficient wireless communication without leading to degradation of the quality of such communication.

[0063] Signalling of Discarded Data

[0064] Figure 6 shows a part schematic, part message flow diagram representation of a first wireless communications system comprising a terminal device 101 (e.g. a UE 14) and an infrastructure equipment 102 (e.g. a gNB / AN 10) in accordance with at least some embodiments of the present technique. The terminal device 101 is configured to transmit signals to and / or receive signals from the wireless communications network, for example, to and from the infrastructure equipment 102. Specifically, the terminal device 101 may be configured to transmit data to and / or receive data from the wireless communications network (e.g. to / from the infrastructure equipment 102) via a wireless radio interface provided by the wireless communications network (e.g., a Uu interface between the terminal device 101 and the Radio Access Network (RAN), which includes the infrastructure equipment 102). Such data transmitted by the terminal device 101 may, for example, include data for applications such as XR. The infrastructure equipment 102 and terminal device 101 are further configured to transmit signals to and / or receive signals from a core network 103, which may be a core network such as that described above with reference to Figure 4. The terminal device 101 and the infrastructure equipment 102 each comprise a transceiver (or transceiver circuitry) 101.1, 102.1, and a controller (or controller circuitry) 101.2, 102.2. Each of the controllers 101.2, 102.2 may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc.

[0065] As shown in the example of Figure 6, the transceiver circuitry 102.1 and the controller circuitry 102.2 of the infrastructure equipment 102 are configured in combination to receive 104, from the core network 103, a first indication that the infrastructure equipment 102 is allowed to discard forward error correction, FEC, data, to receive 105, from the core network 103, a second indication of downlink data and FEC data to be transmitted 108 by the infrastructure equipment 102 to the terminal device 101, wherein the FEC data is for use by the terminal device 101 in controlling errors in the downlink data, to discard 106 at least part of the FEC data instead of transmitting 108 the at least part of the FEC data to the terminal device 101, and to transmit 107, to the core network 103, a third indication of an amount of the discarded 106 FEC data. Here, the discarding 106 of the at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device 101 may only performed by the infrastructure equipment 102 on receipt of the third indication 104 that the infrastructure equipment 102 is allowed to discard FEC data, though in some implementations the infrastructure equipment 102 may be pre-configured to discard FEC data under certain conditions if certain criteria are met. Here, the third indication of the amount of the discarded 106 FEC data may be transmitted by the infrastructure equipment 102 following receipt of every packet or every instance of payload downlink data, but such a third indication of the amount of the discarded 106 FEC data may be transmitted by the infrastructure equipment 102 as an aggregated signal following receipt of a number of packets / instances of payload downlink data and summarising the amount of discarded data across all these packets / instances. Such an aggregated signal may be transmitted in accordance with, for example, a certain periodicity (i.e. every N ms) or upon receipt of a certain threshold amount of downlink data, and such conditions may be pre-defined or may be configurable by the core network or the RAN).

[0066] Essentially, such embodiments of the present technique as exemplified by Figure 6 propose that a RAN reports to the core network (e.g. to the SMF via the AMF) whenever the RAN discards data.

[0067] Furthermore, such embodiments of the present technique propose that the RAN (i.e. gNB) explicitly signals the amount of data which is discarded in RAN to the core network (e.g. to the AMF, which forwards it to the SMF).

[0068] This discarded data can be discarded FEC bits, since they may be dropped under certain circumstances if they are not needed as described above, but can also be discarded data (or FEC bits) due to L2 buffer overflow or congestion leading to the discardTimer expiring at the transmitting PDCP entity. In other words, the infrastructure equipment may be configured to discard the at least part of the FEC data and / or at least a part of the downlink data instead of transmitting the at least part of the FEC data and / or the at least part of the downlink data to the terminal device based on detecting that overflow has occurred at a buffer of the infrastructure equipment and / or based on a current congestion level at the infrastructure equipment (e.g. being higher than a threshold congestion level).

[0069] Figure 7 illustrates various example arrangements and aspects of embodiments of the present technique. Those skilled in the art would appreciate that some steps and signals illustrates in Figure 7 may not be essential steps or features. In step 141 of Figure 7, the core network may indicate to the RAN (e.g. gNB) 102 that it is allowed to discard redundant data, such as FEC data or downlink data. This indication 141 may indicate that FEC data may be discarded only if the downlink data is for one or more specified services., and here, it may be the case that at least one of the specified services supports at least one of: a) the downlink data (i.e. payload) and the FEC data being transmitted separately in separate streams, b) the downlink data (i.e. payload) and the FEC data being transmitted as separate packages within the same stream, and c) the downlink data (i.e. payload) and the FEC data being merged (for example, payload and FEC data may both be included in one or more packets transmitted in the stream) in such a way that not all downlink packets are required to be received by the receiving entity (e.g. UE) in order to successfully receive / decode the downlink data (e.g. 75% of the payload / FEC packets may lead to successful reception of the data, and the other 25% of the payload FEC packets may then be discarded). The indication 141 may be received by the RAN 102 from the AMF 131, where the AMF 131 had in turn received the indication 141 from the SMF 132, which had itself initially received it from the AF 135. Following receipt of this indication 141, the RAN 102 may provide an acknowledgement to the core network (e.g. to the AMF 131 that may be forwarded by the AMF 131 to other nodes within the core network) that indicates the RAN 102 has successfully received and understood the indication 141 that it is allowed to discard redundant data.

[0070] In step 142 of Figure 7, the RAN / gNB 102 may receive downlink data and FEC data that is to be transmitted to a terminal device / UE 101. This downlink / FEC data may be received by the RAN 102 from the UPF 133 specifically, where again, the UPF 133 may have initially received the downlink / FEC data from the AF 135. Such a step, though shown as occurring after the indication 141 of the RAN 102 being allowed to discard redundant data, may in some arrangements be performed before step 141. Following this, in step 143 of Figure 7, the RAN 102 may transmit (at least part of) the downlink data (and, in some cases, at least part of the FEC data) to the UE 101.

[0071] The UE 101 may then transmit an acknowledgement / feedback indication in step 144 of Figure 7 to the RAN 102 that the downlink data has been successfully received (i.e. the UE 101 transmits an ACK to the RAN 102), and this acknowledgement may be received by the RAN 102 before the RAN 102 has transmitted all (or indeed any) of the FEC data to the UE 101. In such a case, the RAN 102 is then able, in step 145 of Figure 7, to discard the FEC data it has not yet transmitted to the UE 101 as it is able to determine that such FEC data is no longer needed by the UE 101 based on the received acknowledgement / feedback indication 144.

[0072] In parallel, the UPF 133 may in some arrangements - as is currently the case in legacy implementations - transmit, in step 146 of Figure 7, a report to the SMF 132 of the amount of used data - though this of course corresponds to the amount of data initially transmitted by the core network to the RAN 102 in step 142, rather than the amount of data actually transmitted by the RAN 102 to the UE 101 when taking into account the discarding of the FEC data in step 145. In accordance with embodiments of the present technique, however, the RAN 102 transmits a separate indication of its own to the core network (e.g. to the AMF 131, for forwarding to the SMF 132) in step 147 of the amount of discarded data discarded in step 145.

[0073] In step 148 of Figure 7, the UPF 133 may then be able to transmit an indication to the AF 135 that the FEC data has been removed and discarded by the RAN 102 since it was not needed by the UE 101. This may be useful for the AF 135 when performing rate adaption, and also regarding for future packets to be transmitted whether (and / or to what extent) encoding of the data is usefiil / necessary or not. The RAN 102 may, at the same time, be configured, in step 149 of Figure 7, to transmit an indication to the UE 101 that it has discarded FEC data (and thus will no longer transmit the discarded FEC data to the UE 101), so that the UE 101 knows it will no longer need to receive further FEC data and so can safely perform actions such as clearing its buffers and / or going to sleep until a next transmission window, for example. The indication transmitted by the RAN 102 in step 149 may have been received by the RAN 102 from the core network initially, e.g. from the AMF 131 as shown in Figure 7.

[0074] In step 150 of Figure 7, the SMF 132, having received the indication from the RAN 102 via the AMF 131 in step 147 of the amount of discarded data discarded in step 145, may then calculate how much data has actually been transmitted by the RAN 102 to the UE 101 by withdrawing this indicated amount of discarded data from the total amount of data initially sent to the RAN 102 by the core network for transmission to the UE 101. This calculated amount of actually transmitted data may then be reported in step 151 of Figure 7 by the SMF 132 to the CHF 133, which may be able to, for example, determine charging based on a more accurate understanding of the used data. The SMF 132 may also transmit an indication of the actually transmitted / used data calculated in step 150 to the AF 135 and / or to the UE 101.

[0075] Embodiments of the present technique therefore propose, firstly, that the AF could indicate when the UE 101 media supports differentiation of payload and FEC (e g. as part of the indication to the RAN that it is allowed to discard FEC or user data) and therefore that the receiver will ignore if FEC packages are lost or not, and secondly that the RAN reports not just that FEC / user data has been discarded, but how much of the (FEC) data has been discarded in order to save bandwidth in the network. Without this, there is no incentive as to why an AF should indicate to the network that active discarding of redundant data (FEC) is allowed. In applications such as XR or other real-time or near real-time applications, which accordingly have low latency requirements, resending data is generally not possible and so adding redundant error correction data is one way to combat errors without affecting latency requirements. Allowing for the discarding of data under certain circumstances - as proposed by arrangements of embodiments of the present disclosure - enable the discarding of FEC (or in some cases user) data to enable more efficient use of bandwidth and resources without negatively impacting quality or latency.

[0076] Figure 8 shows a flow diagram illustrating an example process of communications in a communications system in accordance with embodiments of the present technique. The process shown by Figure 8 is specifically a method operating an infrastructure equipment (e.g. a gNB / radio access node) forming part of a radio access network.

[0077] The method begins in step S 1. The method comprises, in step S2, receiving, from a core network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data. In step S3, the process comprises receiving, from the core network, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device (e g. UE), wherein the FEC data is for use by the terminal device in controlling errors in the downlink data. Then, in step S4, the method comprises discarding at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device. After this, in step S5, the process involves transmitting, to the core network, a third indication of an amount of the discarded FEC data. The process ends in step S6.

[0078] Those skilled in the art would appreciate that the method shown by Figure 8 may be adapted in accordance with embodiments of the present technique. For example, other intermediate steps may be included in such a method, or the steps may be performed in any logical order. Though embodiments of the present technique have been described largely by way of the example communications system shown in Figure 6 and the message flow diagram shown in Figure 7, it would be clear to those skilled in the art that they could be equally applied to other systems to those described herein.

[0079] 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.

[0080] The following numbered paragraphs provide further example aspects and features of the present technique:

[0081] Paragraph 1. A method of operating an infrastructure equipment forming part of a radio access network, the method comprising receiving, from a core network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, receiving, from the core network, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, discarding at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device, and transmitting, to the core network, a third indication of an amount of the discarded FEC data. Paragraph 2. A method according to Paragraph 1, wherein the third indication of the amount of the discarded FEC data is transmitted to an access and mobility function, AMF, of the core network. Paragraph 3. A method according to Paragraph 1 or Paragraph 2, comprising transmitting, to the terminal device, a fourth indication that the infrastructure equipment has discarded the at least part of the FEC data and will not transmit the discarded FEC data to the terminal device.

[0082] Paragraph 4. A method according to any of Paragraphs 1 to 3, wherein the first indication that the infrastructure equipment is allowed to discard FEC data indicates that FEC data may be discarded only if the downlink data is for one or more specified services.

[0083] Paragraph 5. A method according to Paragraph 4, wherein at least one of the specified services supports at least one of: the downlink data and the FEC data being transmitted separately, the downlink data and the FEC data being transmitted together but in separate packets, and the downlink data and the FEC data being merged and transmitted together.

[0084] Paragraph 6. A method according to any of Paragraphs 1 to 5, comprising transmitting, to the terminal device, the downlink data, and receiving, from the terminal device, a feedback indication which indicates that the terminal device has successfully received the downlink data before the infrastructure equipment has transmitted all of the FEC data to the terminal device, and wherein the infrastructure equipment discards the at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device based on the received feedback indication.

[0085] Paragraph 7. A method according to any of Paragraphs 1 to 5, wherein the infrastructure equipment discards the at least part of the FEC data and / or at least a part of the downlink data instead of transmitting the at least part of the FEC data and / or the at least part of the downlink data to the terminal device based on detecting that overflow has occurred at a buffer of the infrastructure equipment.

[0086] Paragraph 8. A method according to any of Paragraphs 1 to 6, wherein the infrastructure equipment discards the at least part of the FEC data and / or at least a part of the downlink data instead of transmitting the at least part of the FEC data and / or the at least part of the downlink data to the terminal device based on a current congestion level at the infrastructure equipment.

[0087] Paragraph 9. An infrastructure equipment forming part of a radio access network, the infrastructure equipment comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to receive, from a core network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, to receive, from the core network, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, to discard at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device, and to transmit, to the core network, a third indication of an amount of the discarded FEC data. Paragraph 10. Circuitry for an infrastructure equipment forming part of a radio access network, the circuitry comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to receive, from a core network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, to receive, from the core network, a second indication of downlink data and FEC data to be transmitted by the transceiver circuitry to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, to discard at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device, and to transmit, to the core network, a third indication of an amount of the discarded FEC data. Paragraph 11. A method of controlling communications within a core network, the method comprising transmitting, to an infrastructure equipment of a radio access network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, transmitting, to the infrastructure equipment, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, and receiving, from the infrastructure equipment, a third indication of an amount of the FEC data that has been discarded by the infrastructure equipment instead of being transmitted be the infrastructure equipment to the terminal device.

[0088] Paragraph 12. A method according to Paragraph 11, wherein the third indication of the amount of the discarded FEC data is received by an access and mobility function, AMF, of the core network.

[0089] Paragraph 13. A method according to Paragraph 12, comprising forwarding, by the AMF to a session management function, SMF, of the core network, the received third indication of the amount of the discarded FEC data.

[0090] Paragraph 14. A method according to Paragraph 13, comprising transmitting, by the SMF to an application function, AF, of the core network based on the forwarded third indication of the amount of the discarded FEC data, a fourth indication that the infrastructure equipment has discarded the discarded FEC data.

[0091] Paragraph 15. A method according to Paragraph 13 or Paragraph 14, comprising calculating, by the SMF based on the forwarded third indication of the amount of the discarded FEC data, a total amount of the downlink data and FEC data transmitted by the infrastructure equipment to the terminal device.

[0092] Paragraph 16. A method according to Paragraph 15, comprising transmitting, to a charging function, CPF, of the core network, a fifth indication of the calculated total amount of the downlink data and FEC data transmitted by the infrastructure equipment to the terminal device.

[0093] Paragraph 17. A method according to Paragraph 15, wherein the SMF calculates the total amount of the downlink data and FEC data transmitted by the infrastructure equipment to the terminal device based on both of the forwarded third indication of the amount of the discarded FEC data and a received sixth indication, from a user plane function, UPF, of the core network, of the amount of downlink data and FEC data transmitted by the UPF to the infrastructure equipment for transmission by the infrastructure equipment to the terminal device.

[0094] Paragraph 18. A method according to any of Paragraphs 11 to 17, wherein the first indication that the infrastructure equipment is allowed to discard FEC data indicates that FEC data may be discarded only if the downlink data is for one or more specified services.

[0095] Paragraph 19. A method according to Paragraph 18, wherein at least one of the specified services supports at least one of: the downlink data and the FEC data being transmitted separately, the downlink data and the FEC data being transmitted together but in separate packets, and the downlink data and the FEC data being merged and transmitted together.

[0096] Paragraph 20. A core network comprising one or more core network entities, the core network being configured to transmit, to an infrastructure equipment of a radio access network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, to transmit, to the infrastructure equipment, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, and to receive, from the infrastructure equipment, a third indication of an amount of the FEC data that has been discarded by the infrastructure equipment instead of being transmitted be the infrastructure equipment to the terminal device.

[0097] Paragraph 21. Circuitry for a core network comprising one or more core network entities, the circuitry being configured to transmit, to an infrastructure equipment of a radio access network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, to transmit, to the infrastructure equipment, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, and to receive, from the infrastructure equipment, a third indication of an amount of the FEC data that has been discarded by the infrastructure equipment instead of being transmitted be the infrastructure equipment to the terminal device.

[0098] Paragraph 22. A wireless communications system comprising an infrastructure equipment according to Paragraph 9 and one or more core network entities of a core network according to Paragraph 20.

[0099] Paragraph 23. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to any of Paragraphs 1 to 8 or any of Paragraphs 11 to 19.

[0100] Paragraph 24. A non-transitory computer-readable storage medium storing a computer program according to Paragraph 23.

[0101] 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.

[0102] 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 units or as part of other functional units. As such, the disclosed embodiments may be implemented in a single unit 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.

[0103] References

[0104] [1] Holma H and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[0105] [2] TR 38.913, “Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14)”, third Generation Partnership Project, vl4.3.0.

[0106] [3] RP-190726, “Physical layer enhancements for NR ultra-reliable and low latency communication (URLLC)”, Huawei, HiSilicon, RAN#83.

[0107] [4] RP-201310, “Revised WID: Enhanced Industrial Internet of Things (loT) and ultra-reliable and low latency communication (URLLC) support for NR,” Nokia, Nokia Shanghai Bell, RAN#88e.

[0108] [5] RP-191575, “NR-based Access to Unlicensed Spectrum”, Qualcomm, RAN#84.

[0109] [6] RP -220285, “Revised SID: Study on XR Enhancements for NR”, Nokia, RAN#95e.

[0110] [7] R2-2302309 (TR38.835), “Study on XR enhancements for NR”, vl.0.2.

[0111] [8] TR 38.838, “Study on XR (Extended Reality) Evaluations for NR (Release 17)”, vl7.0.0.

[0112] [9] Swedish patent application number 2250950-9.

[0113]

[0010] 3GPP TS 38.323, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; Packet Data Convergence Protocol (PDCP) specification (Release 17)”, V17.5.0.

[0114]

[0011] 3GPP TS 23.501, “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; System architecture for the 5G System (5GS); Stage 2 (Release 18)”, V18.4.0.

[0115]

[0012] 3GPP TS 23.502, “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Procedures for the 5G System (5GS); Stage 2 (Release 18)”, VI 8.4.0.

[0116]

[0013] 3GPP TS 32.240, “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Telecommunication management; Charging management; Charging architecture and principles (Release 18)”, VI 8.5.0.

Claims

CLAIMSWhat is claimed is:

1. A method of operating an infrastructure equipment forming part of a radio access network, the method comprising receiving, from a core network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, receiving, from the core network, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, discarding at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device, and transmitting, to the core network, a third indication of an amount of the discarded FEC data.

2. A method according to Claim 1, wherein the third indication of the amount of the discarded FEC data is transmitted to an access and mobility function, AMF, of the core network.

3. A method according to Claim 1, comprising transmitting, to the terminal device, a fourth indication that the infrastructure equipment has discarded the at least part of the FEC data and will not transmit the discarded FEC data to the terminal device.

4. A method according to Claim 1, wherein the first indication that the infrastructure equipment is allowed to discard FEC data indicates that FEC data may be discarded only if the downlink data is for one or more specified services.

5. A method according to Claim 4, wherein at least one of the specified services supports at least one of: the downlink data and the FEC data being transmitted separately, the downlink data and the FEC data being transmitted together but in separate packets, and the downlink data and the FEC data being merged and transmitted together.

6. A method according to Claim 1, comprising transmitting, to the terminal device, the downlink data, and receiving, from the terminal device, a feedback indication which indicates that the terminal device has successfully received the downlink data before the infrastructure equipment has transmitted all of the FEC data to the terminal device, and wherein the infrastructure equipment discards the at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device based on the received feedback indication.

7. A method according to Claim 1, wherein the infrastructure equipment discards the at least part of the FEC data and / or at least a part of the downlink data instead of transmitting the at least part of the FEC data and / or the at least part of the downlink data to the terminal device based on detecting that overflow has occurred at a buffer of the infrastructure equipment.

8. A method according to Claim 1, wherein the infrastructure equipment discards the at least part of the FEC data and / or at least a part of the downlink data instead of transmitting the at least part of the FEC data and / or the at least part of the downlink data to the terminal device based on a current congestion level at the infrastructure equipment.

9. An infrastructure equipment forming part of a radio access network, the infrastructure equipment comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to receive, from a core network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, to receive, from the core network, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, to discard at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device, and to transmit, to the core network, a third indication of an amount of the discarded FEC data.

10. Circuitry for an infrastructure equipment forming part of a radio access network, the circuitry comprising transceiver circuitry, and controller circuitry configured in combination with the transceiver circuitry to receive, from a core network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, to receive, from the core network, a second indication of downlink data and FEC data to be transmitted by the transceiver circuitry to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, to discard at least part of the FEC data instead of transmitting the at least part of the FEC data to the terminal device, and to transmit, to the core network, a third indication of an amount of the discarded FEC data.

11. A method of controlling communications within a core network, the method comprising transmitting, to an infrastructure equipment of a radio access network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, transmitting, to the infrastructure equipment, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, and receiving, from the infrastructure equipment, a third indication of an amount of the FEC data that has been discarded by the infrastructure equipment instead of being transmitted be the infrastructure equipment to the terminal device.

12. A method according to Claim 11, wherein the third indication of the amount of the discarded FEC data is received by an access and mobility function, AMF, of the core network.

13. A method according to Claim 12, comprising forwarding, by the AMF to a session management function, SMF, of the core network, the received third indication of the amount of the discarded FEC data.

14. A method according to Claim 13, comprising transmitting, by the SMF to an application function, AF, of the core network based on the forwarded third indication of the amount of the discarded FEC data, a fourth indication that the infrastructure equipment has discarded the discarded FEC data.

15. A method according to Claim 13, comprising calculating, by the SMF based on the forwarded third indication of the amount of the discarded FEC data, a total amount of the downlink data and FEC data transmitted by the infrastructure equipment to the terminal device.

16. A method according to Claim 15, comprising transmitting, to a charging function, CPF, of the core network, a fifth indication of the calculated total amount of the downlink data and FEC data transmitted by the infrastructure equipment to the terminal device.

17. A method according to Claim 15, wherein the SMF calculates the total amount of the downlink data and FEC data transmitted by the infrastructure equipment to the terminal device based on both of the forwarded third indication of the amount of the discarded FEC data and a received sixth indication, from a user plane function, UPF, of the core network, of the amount of downlink data and FEC data transmitted by the UPF to the infrastructure equipment for transmission by the infrastructure equipment to the terminal device.

18. A method according to Claim 11, wherein the first indication that the infrastructure equipment is allowed to discard FEC data indicates that FEC data may be discarded only if the downlink data is for one or more specified services.

19. A method according to Claim 18, wherein at least one of the specified services supports at least one of: the downlink data and the FEC data being transmitted separately, the downlink data and the FEC data being transmitted together but in separate packets, and the downlink data and the FEC data being merged and transmitted together.

20. A core network comprising one or more core network entities, the core network being configured to transmit, to an infrastructure equipment of a radio access network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, to transmit, to the infrastructure equipment, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, and to receive, from the infrastructure equipment, a third indication of an amount of the FEC data that has been discarded by the infrastructure equipment instead of being transmitted be the infrastructure equipment to the terminal device.

21. Circuitry for a core network comprising one or more core network entities, the circuitry being configured to transmit, to an infrastructure equipment of a radio access network, a first indication that the infrastructure equipment is allowed to discard forward error correction, FEC, data, to transmit, to the infrastructure equipment, a second indication of downlink data and FEC data to be transmitted by the infrastructure equipment to a terminal device, wherein the FEC data is for use by the terminal device in controlling errors in the downlink data, and to receive, from the infrastructure equipment, a third indication of an amount of the FEC data that has been discarded by the infrastructure equipment instead of being transmitted be the infrastructure equipment to the terminal device.

22. A wireless communications system comprising an infrastructure equipment according to Claim 9 and one or more core network entities of a core network according to Claim 20.

23. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to Claim 1 or Claim 11.

24. A non-transitory computer-readable storage medium storing a computer program according toClaim 23.

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