Method, communication device and infrastructure equipment

Abstract

Methods, infrastructure equipment and communication devices for robustly signaling whether a particular uplink transmission opportunity requires retransmission. The communication device indicates whether a particular uplink transmission occasion requires retransmission in an earlier uplink occasion, and the infrastructure equipment selectively schedules uplink resources for retransmission based on the indication from the communication device. If the infrastructure equipment cannot determine whether the particular uplink transmission occasion requires retransmission, the infrastructure equipment schedules uplink resources for the particular uplink transmission occasion.

Description

[0001] Cross-references to related applications

[0002] This application claims priority under the Paris Convention to European patent application EP23172398.2, filed on 9 May 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to infrastructure equipment, communication devices, and methods for transmitting and / or receiving data by infrastructure equipment in a wireless communication network. Background Technology

[0004] The “background” description provided herein is for the purpose of generally presenting the context of this disclosure. To the extent described in this background section, neither the work of the currently attributed inventors nor aspects of the description that may not conform to the prior art at the time of submission are intended to be an acceptance, nor are they implied, of prior art to this invention.

[0005] Previous-generation mobile telecommunications systems, such as those based on the UMTS and LTE architectures defined by 3GPP, can support a wider range of services than the simple voice and messaging services offered by previous-generation mobile telecommunications systems. For example, using the improved radio frequency interface and enhanced data rates provided by LTE systems, users can enjoy high-data-rate applications, such as mobile video streaming and mobile video conferencing, which were previously only available via fixed-line data connections. Therefore, the demand for deploying such networks is very strong, and the coverage areas of these networks (i.e., the geographical locations where network access is available) are expected to continue to increase rapidly.

[0006] Current and future wireless communication networks are expected to regularly and efficiently support communications with an increasing variety of devices with a much wider range of data traffic profiles and device types than current systems were optimized to handle. For example, it is expected that future wireless communication 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 the like. Some of these different types of devices can be deployed in very large numbers, such as low complexity devices to support the “Internet of Things,” and can typically be associated with relatively small amounts of data to be transmitted but with relatively low latency tolerance. Other types of devices, such as those supporting high-definition video streaming, can be associated with relatively large amounts of data to be transmitted but with relatively low latency tolerance. Still other types of devices, such as for autonomous vehicle communications and for other critical applications, can be characterized by a need to transmit data through the network with low latency and high reliability. Depending on the application that is running, a single device type can also be associated with different traffic profiles / characteristics. For example, when a smartphone is running a video streaming application (high downlink data), different considerations can need to be taken into account to efficiently support data exchange with the smartphone than when it is running an Internet browser application (sporadic uplink and downlink data) or used by an emergency response person in an emergency situation for voice communication (data needs to meet strict reliability and delay requirements).

[0007] In view of this, there is expected to be a need for current wireless communication networks, for example, networks that can be referred to as 5G or New Radio (NR) system / New Radio Access Technology (RAT) systems, or even future 6G wireless communication networks, as well as future iterations / releases of existing systems, to be able to efficiently support connectivity for a wide range of devices associated with different applications and different characteristic data traffic profiles and requirements.

[0008] One example of a new service is so-called Ultra-Reliable Low-Latency Communication (URLLC) service, which as the name suggests, requires transmission of data units or packets with high reliability and low communication latency. Another example of a new service is eXtended Reality (XR), which can 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 minimized interaction latency. As such, services such as URLLC and XR represent examples of challenging services for LTE-type communication systems and 5G / NR communication systems and future generations of communication systems.

[0009] 5G NR is continuously evolving and current work plans include 5G-NR-advanced in which some further enhancements are expected, especially to support new use cases / scenarios with higher requirements. The expectations to support these new use cases and scenarios bring new challenges that need to be addressed for efficient handling of communications in wireless communication systems.

[0010] 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, and SUMMARY

[0011] The present disclosure can help to address or alleviate at least some of the above problems.

[0012] According to a first aspect, there is provided a method of operating an infrastructure equipment forming part of a wireless communications network, the infrastructure equipment being configured to transmit signals to and / or receive signals from communications devices over a wireless access interface; the method comprising: monitoring an uplink channel for transmissions from a communications device during a first uplink transmission occasion; attempting to decode a transmission from a communications device in the first uplink transmission occasion; attempting to identify a first retransmission indicator associated with the first uplink transmission occasion; and determining whether to schedule uplink resources on the uplink channel for transmission of one or more retransmissions based on attempting to identify the first retransmission indicator associated with the first uplink transmission occasion, wherein if the infrastructure equipment is unable to identify a retransmission indicator associated with the first uplink transmission occasion, the infrastructure equipment schedules the uplink resources for the communications device to transmit one or more retransmissions of the first transmission which the infrastructure equipment failed to decode.

[0013] According to a second aspect, there is provided a method of operating a communications device configured to transmit signals to and / or receive signals from an infrastructure equipment of a wireless communications network over a wireless access interface; the method comprising: transmitting, to the infrastructure equipment during a first uplink transmission occasion, an indication of whether to retransmit a transmission in a second uplink transmission occasion occurring after the first uplink transmission occasion.

[0014] Various aspects and features of the disclosure are defined in the appended claims.

[0015] 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, and BRIEF DESCRIPTION OF DRAWINGS

[0016] The present disclosure, together with many attendant advantages, will be more fully understood in conjunction with the following detailed description and drawings, in which like reference numerals refer to like parts throughout the several figures, and in which:

[0017] Figure 1 Some aspects of an LTE-type wireless telecommunications system, which can be configured to operate in accordance with some embodiments of the disclosure, are schematically illustrated.

[0018] Figure 2 Some aspects of an NR-type wireless telecommunications system, which can be configured to operate in accordance with some embodiments of the disclosure, are schematically illustrated.

[0019] Figure 3 are schematic block diagrams of an exemplary infrastructure equipment and a communications device, which can be configured to operate in accordance with some embodiments of the disclosure.

[0020] Figure 4 Reproduced from [8] and shows a traffic model for extended reality (XR).

[0021] Figure 5 Time domain parameters for configured grant for physical uplink shared channel (CG-PUSCH) are shown.

[0022] Figure 6 It is demonstrated how redundancy version (RV) pattern is restarted during PUSCH repetition.

[0023] Figure 7 An example of new radio unlicensed (NR-U) channel access on a grid of radio communication resources is shown.

[0024] Figure 8 An example of a primary CG-PUSCH with two supplemental CG-PUSCHs is shown.

[0025] Figures 9A to 9C Example teachings of the disclosure are shown in which an infrastructure equipment determines whether to schedule uplink resources for one or more retransmissions by a communications device.

[0026] Figure 10 An example method for transmitting control information for an uplink transmission occasion in a previous uplink transmission occasion is shown.

[0027] Figure 11 A flowchart of a method of operating an infrastructure equipment in accordance with examples of the disclosure is shown.

[0028] Figure 12 A flowchart of a method of operating a communications device in accordance with examples of the disclosure is shown. DETAILED DESCRIPTION

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

[0030] Figure 1 A schematic diagram showing some basic functionality of a mobile telecommunication network / system 6, which typically operates in accordance with LTE principles, is provided, although other radio access technologies can also be supported, and can be adapted to implement embodiments of the disclosure as described herein. Figure 1 Aspects of the various elements and their respective modes of operation are well-known and have been defined in the relevant standards administered by the 3GPP (RTM) body, and are also described in many relevant textbooks (for example, Holma H. and Toskala A [1]). It will be appreciated that aspects of the operation of the telecommunication network not specifically described herein (for example, relating to specific communication protocols and physical channels used to communicate between different elements) can be implemented in accordance with any known technology, for example, in accordance with the relevant standards and proposed modifications and additions to the relevant standards known.

[0031] The network 6 comprises 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 communication devices 4. Although each base station 1 is shown as a single entity in Figure 1 Although each base station 1 is shown as a single entity in

[0032] Data is transmitted through a radio downlink (DL) from the base stations 1 to the communication devices 4 within their respective coverage areas 3. Data is transmitted through a radio uplink (UL) from the communication devices 4 to the base stations 1. The core network 2 routes data to and from the communication devices 4 through the respective base stations 1 and provides functions such as authentication, mobility management, charging and so on. A terminal device can also be referred to as a mobile station, user equipment (UE), user terminal, mobile radio, communication device and so on. Services provided by the core network 2 can include connectivity to the Internet or to external telephone services. The core network 2 can further keep track of the location of the communication devices 4 so that the communication devices 4 can be contacted (i.e. called) efficiently for the transmission of downlink data to the communication devices 4.

[0033] A base station (example of a network infrastructure equipment) can also be referred to as a transceiver station, a NodeB, an e-NodeB, an eNB, a g-NodeB, a gNB, etc. In this regard, different generations of wireless telecommunication systems are associated with different terminology for elements providing broadly comparable functionality. However, some embodiments of the disclosure can be equally implemented in different generations of wireless telecommunication systems, and for brevity particular terminology can be used irrespective of the underlying network architecture. That is, use of a particular term in some example embodiments is not intended to indicate that the embodiments are limited to only that generation of network with which the particular term can be most closely associated.

[0034] New Radio Access Technology (5G)

[0035] An example configuration of a wireless communication network is shown in Figure 2 which uses some of the terminology proposed and used for NR and 5G. In Figure 2 , a plurality of transmission and reception points (TRPs) 10 are connected to distributed units (DUs) 41, 42 via connection interfaces represented as lines 16. Each TRP 10 is arranged to transmit and receive signals within a radio frequency bandwidth available to the wireless communication network via a wireless access interface. Thus, within the scope of radio communications via the wireless access interface, each TRP 10 forms a cell of the wireless communication network, as represented by the circles 12. Thus, a wireless communication device 14 within the scope of radio communications provided by a cell 12 can perform transceiving of signals with a TRP 10 via the wireless access interface. Each of the distributed units 41, 42 is connected to a central unit (CU) 40 (which can be referred to as a control node) via an interface 46. The central unit 40 is in turn connected to a core network 20, which contains all other functionality required for transmission of data when communicating bi-directionally with wireless communication devices, and which can be connected to other networks 30.

[0036] Figure 2 The elements of the wireless access network shown in Figure 1 may operate in a similar manner to the corresponding elements of the LTE network as described in relation to the example. It will be appreciated that aspects of the operation of the telecommunications network represented in Figure 2 , and of other networks according to embodiments of the disclosure discussed herein, for which no specific description is provided (such as specific communication protocols and physical channels relating to communication between different elements), can be implemented in accordance with any known techniques, for example in accordance with currently used methods for implementing such operation of wireless telecommunication systems, for example in accordance with relevant standards.

[0037] Figure 2The TRP 10 may partially have functions corresponding to a base station or eNodeB in an LTE network. Similarly, the communication device 14 may have functions corresponding to a UE device 4 known for operation with an LTE network. Therefore, it should be understood that the operational aspects of the new RAT network (e.g., specific communication protocols and physical channels for communication between different components) may differ from those known from LTE or other known mobile telecommunications standards. However, it should also be understood that each of the core network components, base stations, and communication devices in the new RAT network will functionally resemble, respectively, the core network components, base stations, and communication devices of an LTE wireless communication network.

[0038] In terms of a wide range of high-level functions, connecting to Figure 2 The core network 20 of the new RAT telecommunications system can be broadly considered to be related to... Figure 1 Corresponding to the core network 2, and each central unit 40 and its associated distributed unit / TRP10 can be broadly considered to provide [something related to] the core network 2. Figure 1 The functions corresponding to base station 1. The term "network infrastructure equipment / access node" can be used to encompass these elements as well as more traditional base station types in wireless telecommunications systems. Depending on the specific application, the responsibility for scheduling planned transmissions on the radio interfaces between the distributed units and communication devices may be borne by the control node / central unit and / or the distributed unit / TRP. Figure 2 In this embodiment, communication device 14 is represented within the coverage area of ​​the first communication cell 12. Therefore, communication device 14 can exchange signaling with the first central unit 40 in the first communication cell 12 via one of the distributed units / TRP10 associated with the first communication cell 12.

[0039] It should also be understood that Figure 2 This is merely one example of the proposed architecture for a telecommunications system based on the new RAT, in which methods based on the principles described herein can be employed, and the functionality disclosed herein can also be applied to wireless telecommunications systems with different architectures.

[0040] Therefore, some embodiments of this disclosure discussed herein can be implemented according to various different architectures (such as, Figure 1 and Figure 2The exemplary architecture shown) in a wireless telecommunications system / network. Thus, it will be appreciated that in any given implementation, the specific wireless telecommunications architecture is not of primary significance to the principles described herein. In this regard, some embodiments of the disclosure can be described generally in the context of communications between a network infrastructure equipment / access node and a communications device, where the specific nature of the network infrastructure equipment / access node and the communications device will depend on the network infrastructure of the current implementation. For example, in some scenarios, the network infrastructure equipment / access node can comprise a base station adapted to provide functionality in accordance with the principles described herein, (e.g. as Figure 1 the LTE-type base station 1 shown in Figure 2 the TRP 10 of the type shown in

[0041] Figure 3 are provided in Figure 2 a more detailed illustration of some components of the network shown in Figure 3 in Figure 2 The TRP 10 (shown as a simplified representation) comprises a wireless transmitter 30, a wireless receiver 32 and a controller or control processor 34 which is operable to control the transmitter 30 and wireless receiver 32 to transmit and receive radio signals to one or more UEs 14 within a cell 12 formed by the TRP 10. As Figure 3 shown, the exemplary UE 14 is shown to comprise a corresponding transmitter 49, receiver 48 and controller 44 configured to control the transmitter 49 and receiver 48 to transmit signals representing uplink data over the wireless access interface formed by the TRP 10 to the wireless communications network, and to receive downlink data in accordance with conventional operation (e.g. signals transmitted by the transmitter 30 and received by the receiver 48).

[0042] The transmitters 30, 49 and receivers 32, 48 (and other transmitters, receivers and transceivers described in relation to examples and embodiments of the disclosure) can comprise radio frequency filters, amplifiers and signal processing components and devices in order to transmit and receive radio signals, e.g. in accordance with the 5G / NR standards. The controllers 34, 44 (and other controllers described in relation to examples and embodiments of the disclosure) can be, for example, microprocessors, CPUs or dedicated chipsets, etc. configured to execute instructions stored on a computer readable medium, such as non-volatile memory. The processing steps described herein can be performed by, for example, a microprocessor in conjunction with random access memory, and operating in accordance with instructions stored on a computer readable medium. For ease of representation, the transmitters, receivers and controllers are shown in Figure 3The various elements will be described in the general context of a method, system, or apparatus, and in the alternative, as a program structure stored on a computer readable storage medium. Such program structure can be downloaded into a working memory of a computer or computing device from a computer readable storage medium or to a computer or computing device from a network, and then executed by the computer or computing device. Such program structure can also be executed as a program running on an apparatus, such as a dedicated integrated circuit, a chip set, or a microprocessor. Program structure can be written in any of a number of different programming languages, including object oriented languages, and it can be converted to a variety of different formats for use with different computing devices.

[0043] As shown in FIG. 1, the TRP 10 also includes a network interface 50, which is connected to the DU 42 by the physical interface 16. The network interface 50 thus provides a communication link for passing data and signaling from the TRP 10 to the core network 20 through the DU 42 and the CU 40. Figure 3

[0044] The interface 46 between the DU 42 and the CU 40 is referred to as the Fl interface, which can be a physical interface or a logical interface. The Fl interface 46 between the CU and the DU can operate in accordance with the 3GPP TS 38.470 and 3GPP TS 38.473 specifications, and can be formed by an optical fiber or other wired or wireless high-bandwidth connection. In one example, the connection 16 from the TRP 10 to the DU 42 is implemented by an optical fiber. The connection between the TRP 10 and the core network 20 can generally be referred to as the backhaul, which includes the network interface 50 from the TRP 10 to the interface 16 of the DU 42, and the Fl interface 46 from the DU 42 to the CU 40.

[0045] eURLLC, NR-U, and extended reality

[0046] Systems incorporating NR technology are expected to support different services (or service types) that can be characterized by different requirements for latency, data rate, and / or reliability. For example, an enhanced mobile broadband (eMBB) service is characterized by high capacity, requiring support of up to 20 Gb / s. Ultra-reliable low-latency communication (URLLC) service requirements are: a single transmission of a 32-byte packet within 1 ms with 1-10 -5 (99.999%) or higher (99.9999%) reliability from a radio protocol layer 2 / 3 SDU ingress point to a radio protocol layer 2 / 3 SDU egress point of a radio interface. Massive machine type communications (mMTC) is another example of a service that can be supported by an NR-based communication network. In addition, systems can be expected to support further enhancements related to industrial internet of things (IIoT) to support services with new requirements of high availability, high reliability, low latency, and in some cases, high-accuracy positioning.

[0047] ​Enhanced URLLC (eURLLC) [3] [4] specifies features that require high reliability and low latency, such as factory automation, transportation industry, power distribution, etc. It should be understood that uplink control information (UCI) for URLLC and eMBB will have different requirements.

[0048] Another such service incorporating NR technology is 5G NR in unlicensed spectrum (NR-U) [5], which enables devices to utilize shared unlicensed spectrum bandwidth. As specified in [5], features such as Listen Before Talk (LBT) have been incorporated into the NR frame structure for NR-U operation in unlicensed bands.

[0049] Extended Reality (XR) and cloud gaming refer to various types of augmented, virtual, and mixed environments in which human-to-computer and human-to-human communication is facilitated with the aid of handheld and wearable end-user devices (UEs). XR and cloud gaming are two applications that have recently been developed and are considered important for NR Rel-18 and beyond (also referred to as advanced 5G) [6].

[0050] XR traffic is rich in video, especially in the downlink, with a typical frame rate of 60 Hz [7], which results in a non-integer periodicity of data transmission in NR, i.e., a period that is not an integer number of subframes, and in this example, the period is 16.67 ms. Due to frame encoding delay and variations in network transit time, packets arriving at the gNB can experience random jitter. The non-integer and jitter characteristics of XR traffic are referred to as quasi-periodic traffic. In addition to jitter, packet size also varies within a range; i.e., the packet size in each period is random. Figure 4 Jitter and random packet size for UL traffic is shown in FIG. 1.1-1, which is based on a similar figure in [8]. Figure 5 .1.1-1).

[0051] Figure 4 A single traffic model for XR is shown. The first packet k 51 is transmitted, which represents an Internet Protocol (IP) packet belonging to video frame k At a later point in time, which is on average the inverse of the frame generation rate (i.e., 1 / fps) as represented by arrow 55, the second packet k+1 52 is transmitted, which represents an IP packet belonging to video frame k+1 Variable packet size, following a probability distribution, is shown by arrow 53, while variable jitter, also following a probability distribution, is represented by arrow 54.

[0052] In legacy 5G systems, Configured Grant PUSCH (CG-PUSCH) and SPS Physical Downlink Shared Channel (PDSCH) are used to support traffic with known periodicity and packet size (e.g. voice). In legacy systems, CG-PUSCH (discussed in more detail below) and SPS assume that the transport block size (TBS) of PUSCH and PDSCH for the traffic is the same in each period. However, in XR traffic, the payload of the quasi-periodic traffic can not be the same but varies within a range.

[0053] Rel-15 Configured Grant

[0054] As is well known to those skilled in the art, a UE uses the Physical Uplink Shared Channel (PUSCH) for uplink data transmission. The PUSCH resources for PUSCH transmission can be scheduled by the gNB using either dynamic grant (DG) or configured grant (CG).

[0055] In dynamic grant PUSCH (DG-PUSCH), when uplink data arrives in its buffer, the UE typically sends a scheduling request (SR) to the gNB. In response to receiving the SR, the gNB then sends an uplink grant to the UE, e.g. by using the downlink control information (DCI) carried by the Physical Downlink Control Channel (PDCCH) in DCI format 0_0, 0_1 or 0_2, where the uplink grant schedules resources for PUSCH. The UE then transmits its uplink data using the scheduled PUSCH (i.e. DG-PUSCH).

[0056] It is observed that the use of DG-PUSCH introduces latency as the UE needs to initiate an SR and has to wait for the uplink grant before scheduling the PUSCH resources. For periodic and periodic traffic, DG-PUSCH results in sending multiple SRs and uplink grants which is not an efficient way of utilizing resources. So, recognizing the drawbacks of DG-PUSCH, Configured Grant PUSCH (CG-PUSCH) was introduced in NR. In CG-PUSCH, the UE is preconfigured with periodic PUSCH resources using Radio Resource Control (RRC) configuration so that the UE can transmit its uplink data in any of these periodically occurring CG-PUSCH resources without the need to request through an SR. There are two types of CG-PUSCH: Type 1 CG-PUSCH : Once a CG-PUSCH resource is RRC configured, the UE can use the CG-PUSCH resource without activation; and Type 2 CG-PUSCHCG-PUSCH resources are first configured by RRC. A UE can use CG-PUSCH resources only if it receives an activation DCI, which is an UL grant with configured scheduling - radio network temporary identifier (CS-RNTI). Once a CG-PUSCH is activated, the UE can use the CG-PUSCH until the CG-PUSCH is deactivated by another DCI. Type 2 CG-PUSCH provides better control for the gNB scheduler and thus more efficient utilization of resources.

[0057] In time domain, a CG-PUSCH consists of a period P CG , a number of repetitions K = {1, 2, 4, 8}, a duration of the PUSCH L and a starting symbol offset relative to the slot boundary of the PUSCH S . An example is shown in Figure 5 where the CG-PUSCH has a period P CG = 224 symbols (or 16 slots), a number of repetitions K = 4, a duration L = 9 symbols and a starting symbol S = 3 symbols from the beginning of the slot boundary. The CG-PUSCH consists of transmission occasions (TOs), where a TO is an occasion for the UE to transmit uplink data. Note here that the UE does not need to use a TO, i.e. a CG-PUSCH resource, if the UE does not have uplink data to transmit. For example, in slot n , the UE does not have any uplink data and thus does not transmit anything in the TOs of this CG period, but in the next CG period starting at slot n + 16, the UE has uplink data and thus uses the TOs in this CG period to transmit four repetitions of the uplink data.

[0058] The first TO in a CG period is associated with redundancy version RV = 0. If the number of repetitions K > 1, each TO in a CG period is associated with an RRC-configured RV pattern, where the RV pattern can be {0, 2, 3, 1}, {0, 3, 0, 3} or {0, 0, 0, 0}. The RV pattern is configured in the RRC parameter repK-RV . For example, in Figure 5 , the RV pattern = {0, 2, 3, 1}. The first PUSCH transmission in a CG period must always start with RV = 0. For a number of repetitions K = 8, the RV pattern is cycled after the fourth repetition; i.e. after the fourth repetition, the RV pattern restarts. For example, in Figure 6In this case, RV pattern = {0, 2, 3, 1} and the number of repetitions K = 8. Here, the UE cycles the RV at the fifth repetition, where the RV pattern restarts at the fifth TO of the CG period in slot n + 4.

[0059] Since hybrid automatic repeat request (HARQ) is used for PUSCH transmission, each PUSCH is associated with a HARQ process number (HPN), where there are 16 HARQ processes, i.e., HPN = 0 to 15. In DG-PUSCH, the HPN is indicated in the UL grant. For CG-PUSCH, since there is no UL grant, each CG period is associated with a HPN, and depends on the starting symbol of the first TO in the CG period relative to SFN = 0 O CG (in units of symbols), the periodicity P CG (in units of symbols), and the number of HARQ processes configured for CG-PUSCH N HARQ [7] (i.e., a gNB can configure less than 16 HARQ processes for CG-PUSCH), i.e.,

[0060] where, . is a floor function, and O CG is calculated relative to the first symbol of the first slot of the radio frame relative to SFN = 0.

[0061] Retransmission of CG-PUSCH is scheduled using UL grant. That is, DG-PUSCH is used for retransmission of CG-PUSCH that failed to be successfully decoded at the gNB. If the UE does not receive the UL grant for retransmission of CG-PUSCH in the preconfigured timing T CG-ACK , the UE considers the CG-PUSCH to be successfully received. The timing T CG-ACK is configured by the RRC parameter configuredGrantTimer .

[0062] Channel access in NR-U

[0063] In the following paragraphs, an explanation of current proposals for accessing communications from unlicensed bands is provided. In unlicensed bands, two or more systems can operate to communicate using the same communication resources. Thus, transmissions from different systems can interfere with each other, especially for example when each of the different systems is configured according to different technical standards (e.g. Wi-Fi and 5G). Of course, transmissions from systems operating according to the same standard can also cause interference. Therefore, a regulation requires each transmitter operating in unlicensed bands to use an LBT protocol for reducing interference between different systems sharing the band (systems operating according to the same or different technical standards from each other). In LBT, a device wishing to transmit a packet will first sense the band for any energy level above a threshold to determine whether any other device is transmitting, i.e. listening, and if no transmission is detected, the device will transmit its packet. Otherwise, if the device senses a transmission from another device, the device will back off and try again later.

[0064] In NR-U, channel access can be dynamic (also referred to as load-based equipment) or semi-static (also referred to as frame-based equipment). As shown in Figure 7 The dynamic channel access scheme consists of one or more clear channel assessment (CCA) phases in a contention window, and a subsequent channel occupancy time (COT) phase. LBT is performed by an NR-U device (e.g. gNB or UE) wishing to perform a transmission during the CCA phase. According to the CCA phase, the NR-U device listens to one or more CCA slots, and if no other transmission is detected after the CCA phase (i.e. determines that the energy level is below a threshold for the duration of the one or more CCA slots), the NR-U device enters the COT phase, in which it can transmit its packet in the COT resources. In dynamic channel access (DCA), the CCA phase and the COT phase can have different lengths between different systems, while in semi-static channel access, the CCA phase and the COT phase have fixed time windows and are synchronized for all systems sharing the band. More details on channel access in NR-U can be found in co-pending international patent application with international publication number WO 2022 / 018230 [9].

[0065] A COT can be shared by multiple devices; i.e. a gNB can initiate a COT, which can then be shared with one or more UEs. For example, a gNB can initiate a COT, and then can transmit an UL grant to a UE, which can then transmit a PUSCH using the COT. A device using a COT initiated by another device can not need to perform a CCA, or only a short CCA. It will be appreciated by the skilled person that a UE can also initiate a COT.

[0066] CG-UCI

[0067] In Rel-15 and Rel-16 eURLLC, the HARQ process number (HPN) and redundancy version (RV) for each CG-PUSCH transmission is fixed per TO and known to the gNB. However, in Rel-16 NR-U, a UE can use any of the TOs for the first PUSCH transmission, and different TBs (i.e., with different HPN) can be transmitted in the CG occasions, and thus the gNB needs to know the HPN and RV of these CG-PUSCHs. To provide this information to the gNB, CG uplink control information (CG-UCI) is introduced for Rel-16 NR-U, which consists of the following fields: HARQ process number (HPN) (indicated by 4 bits); Redundancy version (RV) (indicated by 2 bits); New data indicator (NDI) (indicated by 1 bit); and COT sharing information (indicated by log2 C DL bits, where, C DL is the number of entries in the lookup table, indicating the location of the DL resources that the gNB can use within the UE-initiated COT).

[0068] The CG-UCI is multiplexed into the CG-PUSCH transmission.

[0069] Rel-18 supplemental CG-PUSCH

[0070] In Rel-18, supplemental CG-PUSCH is proposed for NR, where an additional CG-PUSCH (i.e., supplemental CG-PUSCH) can be configured for each of the multiple CG-PUSCHs, and these supplemental CG-PUSCHs can be dynamically activated using the CG-UCI in the primary (i.e., first) CG-PUSCH. Since the supplemental CG-PUSCHs are dynamically activated, they are only used when needed. If they are not activated, the allocated resources can be reallocated by the gNB to schedule other traffic or UEs. The first CG-PUSCH transmission occasion within the period of the CG-PUSCH configuration is referred to as the primary CG-PUSCH. The subsequent CG-PUSCH transmission occasions within the period of the CG-PUSCH configuration are referred to as the supplemental CG-PUSCHs.

[0071] Figure 8 An example of this operation is shown in FIG. 18, where a UE is configured with a CG-PUSCH configuration, CG#1, with a repetition number of 2.K =1 to support XR traffic. For XR traffic with a minimum TBS of 0.5 Mbit and a maximum TBS of 1.5 Mbit, to reduce resource wastage, the CG-PUSCH is configured with a TBS corresponding to the minimum XR packet size of 0.5 Mbit, and two supplementary CG-PUSCHs (each also of size 0.5 Mbit), allowing the primary and supplementary CG-PUSCHs between them to support up to the maximum XR packet size of 1.5 Mbit when needed. In Figure 8 the example, the UE can have a 1.0 Mbit XR packet arrive in its buffer by slot n and thus the UE is able to use CG#1 to transmit this XR packet. Since the primary CG-PUSCH of 0.5 Mbit (labelled 1-0 in Figure 8 is not enough to completely empty the UE buffer, the CG-UCI transmitted by the UE within the primary CG-PUSCH 1-0 activates the supplementary CG-PUSCH 1-1 to carry the remaining 0.5 Mbit of data from the UE buffer. Since the supplementary CG-PUSCH 1-2 is not needed to transmit any XR packet, it is not activated by the UE and thus can be used by the gNB to schedule other traffic or another UE.

[0072] Those skilled in the art will understand that Figure 8 the example of is merely illustrative of one way in which a supplementary CG-PUSCH can be implemented, as the details of the supplementary CG-PUSCH are not limited.

[0073] One of the pieces of information that an XR device needs to transmit is its position and orientation (collectively referred to as its pose), so that the XR application can determine where the user is located and in which direction the user is looking, and respond appropriately (i.e., track the pose of the XR viewer). For example, if a VR headset displaying a virtual room sends pose information to an XR server indicating that the wearer of the VR headset is looking up, then the server will display a video of the ceiling of the virtual room instead of the floor. In addition to pose information, an XR device can also send other types of control information on the uplink to the server. In addition, an XR device can transmit video and / or audio data for use by a corresponding party of the XR user, such as, for example, an XR application server. Video data and / or audio data typically require a large amount of data and are not very time sensitive. On the other hand, pose / control UL transmissions in XR are typically small in size and are more time sensitive. For example, if a person looks up and then looks down, the video needs to display the corresponding ceiling and floor in a timely manner. Because pose / control UL transmissions are very time sensitive, if an UL transmission including such pose or control information fails, retransmitting the information again would not be of much benefit. For example, if a person looks up and then looks down, and the pose information of the person looking up fails to reach the server, retransmitting the pose information again would not be of much benefit because by the time the pose information is retransmitted, the person can have already looked down and thus no longer expect to look at the ceiling. Recognizing the characteristics of pose / control UL transmissions for services such as XR, a proposal was made that such UL transmissions do not need HARQ retransmission, and because they are small in data size, can be transmitted using a very robust (i.e., low) MCS, thereby ensuring their reliability

[10] . In addition, CG-PUSCH without retransmission also has the benefit of saving resources and conserving power because no resources are needed for retransmission and the UE does not have to monitor for potential retransmissions from the gNB.

[0074] In

[10] , it was proposed to set Figure 8 to zero after the discussion of configuredGrantTimer ( T CG-ACK ) is set to zero. That is, the UE stops retransmission and flushes its HARQ buffer immediately after transmitting the primary CG-PUSCH. However, in the current 3GPP system, configuredGrantTimer is set to the minimum value equal to one CG-PUSCH period. So, the current specification does not allow the configuration of configuredGrantTimer = 0. Therefore, introducing the value 0 to configuredGrantTimer will have backward compatibility issues because legacy UEs can not understand the new value. Therefore, a new timer is needed that includes the zero value, such as configuredGrantTimer_Rel18, which is only understood by Rel-18 UEs supporting the no-retransmission feature. A new behavior needs to be introduced so that the UE overrides the old timer with the new timer. In the current 3GPP system, there are up to 12 CG-PUSCH configurations, and in this case, each of these CG-PUSCH configurations can be independently configured with the new timer parameter, i.e., the gNB can decide which CG-PUSCH is no-retransmission and which CG-PUSCH needs HARQ retransmission by setting the new timer to 0. Therefore, this new timer is per CG configuration, meaning that all HARQ processes with this CG-PUSCH will be set to zero. In other words, different HARQ processes within the same CG-PUSCH configuration cannot have other values than zero. This limits the flexibility of using this CG-PUSCH for other transmissions / services that need retransmission.

[0075] In other applications, such as in Non-Terrestrial Network (NTN) systems, the Round Trip Time (RTT) is very long, and therefore, in some operations, HARQ retransmission is not practical because the UE has to wait a considerable amount of time to flush its HARQ buffer for acknowledgement. Recognizing this, HARQ mode B was introduced in NTN, where for a configured set of HARQ Process Numbers (HPNs), HARQ retransmission is disabled. It was proposed in

[10] to also support HARQ mode B in Terrestrial Networks (TN), allowing CG-PUSCH to operate without HARQ retransmission. However, HARQ mode B is configured on a per-HPN basis; i.e., whether to use HARQ retransmission depends on the HPN of the PUSCH. This can be acceptable for dynamic PUSCH, where the HPN is indicated by the gNB, but for CG-PUSCH, the HPN is calculated from the starting symbol of the CG-PUSCH transmission occasion and its periodicity, which is not easily controlled by the gNB or the UE, and therefore, HARQ mode B is not suitable for CG-PUSCH operation.

[0076] Another approach proposed for NTN is to disable the HARQ RTT timer for no-retransmission CG-PUSCH, as introduced in Rel-17, but in a way adapted to XR traffic. Therefore, a new RRC parameter can be introduced to disable the HARQ RTT timer for a specific CG-PUSCH configuration. drx-HARQ-RTT-TimerUL However, this approach has the same drawback as the approach of setting configuredGrantTimer to 0, as mentioned above, because disabling the HARQ RTT timer per CG-PUSCH configuration means that all HARQ processes using this CG-PUSCH will be disabled. Therefore, this limits the flexibility of using this CG-PUSCH for other transmissions / services that need retransmission.

[0077] No-retransmission indicator

[0078] One proposal to overcome the deficiencies of the above approaches is to dynamically indicate in the UCI of CG-PUSCH (e.g., CG-UCI) (e.g., using a no-retransmission indicator, referred to herein as a retransmission indicator) whether the current CG-PUSCH is HARQ no-retransmission or requires HARQ retransmission. This enables the UE to indicate on a per CG-PUSCH occasion basis whether the CG-PUSCH transmission requires HARQ retransmission. The benefit of this option is that it provides full flexibility, allowing any CG-PUSCH occasion (not just specific CG-PUSCH configurations) to operate with or without HARQ retransmission. However, one potential drawback of this approach is that the gNB and UE can become out of sync if the dynamic indication of UCI is monitored incorrectly. In other words, if the dynamic indication is included in a failed transmission, it is likely that the gNB will not know whether the UE expects a retransmission.

[0079] Accordingly, in accordance with examples of the present disclosure, when a retransmission indicator cannot be decoded at the gNB, a network infrastructure equipment such as a gNB determines that it will schedule uplink resources for a communication apparatus such as a UE to retransmit. This can be the case, for example, when the gNB receives an uplink transmission in a particular uplink transmission occasion but is unable to decode the retransmission indicator. Similarly, this can occur when the gNB does not receive any transmission during a particular uplink transmission occasion and does not know whether the communication apparatus needs a retransmission in the particular uplink transmission occasion (i.e., the gNB does not know the value of the retransmission indicator). In this way, the gNB schedules uplink resources for retransmission by default (e.g., in the case of a transmission failure).

[0080] The retransmission indicator can be included in CG-UCI, which is included in the CG-PUSCH transmission, but is encoded at the UE independently of the CG-PUSCH and decoded at the gNB separately from the CG-PUSCH. So, if the gNB cannot decode the CG-UCI, the gNB can schedule a retransmission for the CG-PUSCH, as the gNB does not know whether the UE has determined that the CG-PUSCH should be HARQ no retransmission. In this case, if the UE triggered a HARQ retransmission for the CG-PUSCH, the UE will monitor the HARQ retransmission signalling, which corresponds to the gNB default behaviour. However, if the UE triggered a HARQ no retransmission approach for the CG-PUSCH, the UE will not monitor the HARQ retransmission signalling. While this leads to unnecessary waste of UL resources for scheduling a retransmission (which the UE does not intend to use), the probability of this waste occurring is low, as the CG-UCI (control information) typically has a relatively low coding rate (compared to the data within the CG-PUSCH), such that the mischeck probability of the CG-UCI is at least 0.01 (1%). Therefore, by allowing a separate CG-PUSCH occasion to be set with or without HARQ retransmission provides flexibility, while ensuring that the gNB and UE behaviour remain synchronised to minimise resource wastage.

[0081] Figures 9A to 9C An example of the above procedure is shown. Figures 9A to 9C A partial schematic diagram and a partial message flow diagram of a first wireless communications system is shown, which includes a communications device 91 (e.g. a UE 14) and an infrastructure equipment 92 (e.g. a gNB 10) in accordance with at least some embodiments of the present technique. The communications device 91 is configured to transmit signals to and / or receive signals from a wireless communications network, e.g. to transmit signals to and receive signals from the infrastructure equipment 92. In particular, the communications device 91 can be configured to transmit data to and / or receive data from the wireless communications network (e.g. to transmit data to / from the infrastructure equipment 92) over a wireless radio interface provided by the wireless communications network (e.g. a Uu interface between the communications device 91 and a radio access network (RAN) including the infrastructure equipment 92). Such data transmitted by the communications device 91 may, for example, comprise data for an application such as XR. The communications device 91 and the infrastructure equipment 92 each comprise a transceiver (or transceiver circuitry) 91.1, 92.1 and a controller (or controller circuitry) 91.2, 92.2. Each of the controllers 91.2, 92.2 may, for example, be a microprocessor, a CPU, or a dedicated chipset, etc.

[0082] As Figure 9AIn the example shown, the transceiver circuitry 91.1 and controller circuitry 91.2 of the communications device 91 are configured in combination to transmit the uplink transmission 93 on the uplink channel in the first uplink transmission occasion 94, during which the transceiver circuitry 92.1 and controller circuitry 92.2 of the infrastructure equipment 92 are configured to monitor the uplink channel for uplink transmissions from the communications device 91. Figure 9A In the example shown, the uplink transmission 93 is at least partially received by the infrastructure equipment 92 (such that the infrastructure equipment is able to determine at least that the uplink transmission 93 was transmitted by the communications device 91), the infrastructure equipment 92 attempts 95 to identify the retransmission indicator associated with the first uplink transmission occasion 94. The infrastructure equipment 92 can attempt to identify the retransmission indicator associated with the first uplink transmission occasion 94 based on information included in the uplink transmission 93 and / or based on information included in one or more previous uplink transmissions. In some cases, the infrastructure equipment is able to decode the retransmission indicator included in the uplink transmission 93, but is not able to decode the entire uplink transmission 93 (i.e. only part of the uplink transmission 93 is received by the infrastructure equipment 92).

[0083] Based on identifying the retransmission indicator associated with the first uplink transmission occasion 94, the infrastructure equipment 92 determines whether to schedule uplink resources for retransmission of the uplink transmission 93. If the retransmission indicator indicates that retransmission is required, the infrastructure equipment 92 determines that it will schedule uplink resources for the communications device 91 to perform retransmission 97 of the uplink transmission. The infrastructure equipment 92 can transmit an UL grant 96 (or other scheduling message) to the communications device 91 scheduling resources (e.g. DG-PUSCH) for retransmission 97 of the uplink transmission 93 in a second uplink transmission occasion 98. The infrastructure equipment 92 then monitors for the retransmission 97 during the dynamically scheduled second uplink transmission occasion 98. Conversely, if the retransmission indicator indicates that retransmission is not required, the infrastructure equipment 92 determines not to schedule uplink resources for the communications device 91 to perform retransmission 97 of the uplink transmission, and the infrastructure equipment 92 does not monitor for any retransmission 97.

[0084] In some cases, as shown in Figure 9B and Figure 9C The infrastructure equipment 93 can not receive the uplink transmission 93, and the infrastructure equipment 92 can not be able to identify the retransmission indicator associated with the first uplink transmission occasion 94. Therefore, the infrastructure equipment can not know whether the communications device 91 has flagged the uplink transmission 93 as retransmission free. Therefore, according to the present example, the infrastructure equipment 92 determines that it will schedule uplink resources for the communications device 91 to perform retransmission 97 of the uplink transmission, and is able to monitor for the retransmission 97 as described above in relation to Figure 9AThe uplink resources for retransmission of the uplink transmission 93 are scheduled and monitored by the infrastructure equipment 92 in the described manner.

[0085] In some cases, the infrastructure equipment 92 is able to determine whether the uplink transmission occasion 94 comprises a failed transmission and can monitor for a retransmission accordingly. For example, the infrastructure equipment 92 can check for the presence of one or more demodulation reference signals (DMRS) during the uplink transmission occasion 94 by correlating any detected signals with known DMRS sequences. If the correlation peak is above the noise level (i.e. by using a defined threshold), the infrastructure equipment 92 determines that there was an uplink transmission during the uplink transmission occasion 94, but that the uplink transmission was not successfully decoded at the infrastructure equipment 92. If no DMRS is detected, the infrastructure equipment 92 is not necessarily able to conclude that no failed transmission occurred during the uplink transmission occasion 94 and can attempt to determine this based on other factors such as whether there was an indication of an uplink transmission using the uplink transmission occasion 94 in a previous uplink transmission occasion, whether there was an indication of a retransmission indicator for the uplink transmission occasion 94 in a previous uplink transmission occasion, and / or whether there was an indication of an uplink transmission using the uplink transmission occasion configuration corresponding to the uplink transmission occasion 94.

[0086] In some cases, the infrastructure equipment 93 can not have received the uplink transmission 93, however, the infrastructure equipment 92 can still identify a retransmission indicator for the first uplink transmission occasion 94. For example, the retransmission indicator for the first uplink transmission occasion 94 can have been indicated to the infrastructure equipment 92 by the communications device 91 in an earlier uplink transmission occasion. The retransmission indicator (in any uplink transmission occasion, including the first uplink transmission occasion 94) can be transmitted to the infrastructure equipment 92 or can be indicated to the infrastructure equipment 92 using one or more other parameters (in any uplink transmission occasion, including the first uplink transmission occasion 94) transmitted to the infrastructure equipment 92. For example, when deploying a CG-PUSCH configuration in unlicensed spectrum, the infrastructure equipment 92 can identify the retransmission indicator based on a HARQ process number (HPN) or an identifier. The indication of the retransmission indicator can be included in the CG-UCI or a MAC CE of the CG-PUSCH.

[0087] The indication of the retransmission indicator can be indicated to the infrastructure equipment in multiple uplink transmission occasions. For example, in the case of a CG-PUSCH configuration, the retransmission indicator can be indicated to the infrastructure equipment in each uplink transmission occasion in which the communications device 91 is scheduled to transmit the uplink transmission 93. The indication of the retransmission indicator can be included in the CG-UCI or a MAC CE of the CG-PUSCH. Figure 8In the illustrated example, the indication of the retransmission indicator for each CG-PUSCH and supplemental PUSCH occasion in a set of PUSCH occasions can be included in each PUSCH occasion in the set of PUSCH occasions. Alternatively, the indication of the retransmission indicator for each subsequent PUSCH occasion in a set of PUSCH occasions can be indicated in each PUSCH occasion in the set of PUSCH occasions. Thus, a single miss of the CG-UCI or MAC CE of the CG-PUSCH can not result in the infrastructure equipment not knowing whether the communication device has requested a retransmission, further minimising resource wastage.

[0088] In addition to the uplink transmission occasion including an indication of a retransmission indicator for a future uplink transmission occasion, the uplink transmission occasion can additionally or alternatively include an indication of a retransmission indicator for a previous uplink transmission occasion. Thus, the infrastructure equipment is able to determine whether any changes to the transmission parameters (e.g. transmission power) of the communication device are required, for example, based on whether the previous uplink transmission occasion required a retransmission and whether the uplink transmission was successfully decoded at the infrastructure equipment.

[0089] Additionally or alternatively, the communication device can indicate whether a particular uplink transmission occasion is for any uplink transmission. That is, the uplink transmission can indicate whether a future (and / or past) uplink transmission occasion is for transmitting an uplink transmission. Thus, the infrastructure equipment is able to better determine whether any failed transmissions have occurred, and thus whether a retransmission can be required. For example, the CG-UCI can be included in each transmitted CG-PUSCH, where the CG-UCI indicates whether a future CG-PUSCH occasion is used. In other words, the CG-UCI includes an indication of unused CG-PUSCH occasions (i.e. supplemental CG-PUSCH occasions) in the period of the single CG-PUSCH configuration.

[0090] An example of this procedure is shown in Figure 10 , where the UE is configured with a single CG-PUSCH index 1 with a periodicity of 8 ms or 8 slots. In the first period of 8 slots, there are four occasions configured for data transmission (slots 0, 2, 4, 6). The UE has data to transmit and the data is available for transmission in the first period of 8 slots. n The UE estimates that the uplink data will only occupy three occasions / slots n+3 . So, based on the available data (approximately 3 Mbit), the UE estimates that the uplink data will only occupy three occasions / slots n, n+1 and n+2 . Thus, the UE will include UCI in the PUSCH of each transmitted PUSCH, where the UCI indicates that the last occasion n , n+1 and n+2 is used for a retransmission. The UCI is included in the PUSCH of each of the occasions / slots n+3that there is no data to transmit during the period of the first uplink transmission occasion. Based on this information, if the gNB does not decode the CG-PUSCH / UCI in a certain occasion / slot among the occasions / slots n , n+1 or n+2 , the gNB can rely on the UCI information transmitted on different occasions / slots which indicates that there will be a transmission in the occasions / slots n+1 and n+2 . Thus, the gNB is able to determine whether there was a failed transmission and then schedule uplink resources for retransmission of the PUSCH, as the gNB is not aware whether the UE has triggered a HARQ retransmission or no retransmission for the transmitted (and unsuccessfully decoded) PUSCH. Similar procedure applies for the second and fourth periods as shown in Figure 10 .

[0091] Additionally or alternatively, the communications device can indicate whether a particular uplink transmission occasion configuration is used for any uplink transmission. As mentioned above, the communications device can be configured with a plurality of uplink transmission occasion (e.g. CG-PUSCH) configurations, in some cases up to 12 different configurations. The communications device can indicate to the infrastructure equipment that a particular configuration (i.e. all uplink transmission occasions with that configuration) is not used for uplink transmission. This can be indicated in a CG-PUSCH occasion with the same or different configuration as the particular CG-PUSCH occasion configuration indicated. Thus, the infrastructure equipment can determine that the particular uplink transmission occasion with the particular configuration does not include an uplink transmission and therefore no failed transmission occurred during the uplink transmission occasion.

[0092] Figure 11 A flowchart illustrating a method 110 of operating an infrastructure equipment in accordance with examples of the present disclosure is shown. At step 111, the infrastructure equipment monitors an uplink channel for a transmission from a communications device during a first uplink transmission occasion. At step 112, the infrastructure equipment attempts to decode the transmission from the communications device in the first uplink transmission occasion. At step 113, the infrastructure equipment attempts to identify a first retransmission indicator associated with the first uplink transmission occasion. At step 114, the infrastructure equipment determines whether to schedule uplink resources on the uplink channel for one or more retransmissions of the transmission based on attempting to identify the first retransmission indicator associated with the first uplink transmission occasion, wherein if the infrastructure equipment is unable to identify the retransmission indicator associated with the first uplink transmission occasion, the infrastructure equipment schedules the uplink resources for the communications device to transmit one or more retransmissions of the first transmission that the infrastructure equipment failed to decode.

[0093] Figure 12A flow diagram illustrating a method 120 of operating a communications device in accordance with examples of the disclosure is shown. At step 121, the communications device transmits, to an infrastructure equipment during a first uplink transmission occasion, an indication of whether a retransmission of a transmission is to be made in a second uplink transmission occasion occurring after the first uplink transmission occasion. At step 122, the communications device optionally transmits, to the infrastructure equipment, a first transmission, the first transmission comprising uplink data. At step 123, the communications device optionally receives, from the infrastructure equipment, a transmission scheduling uplink resources for a retransmission of the first transmission. At step 124, the communications device optionally retransmits the uplink data (i.e. retransmits the first transmission) using the scheduled uplink resources based on whether a retransmission of the transmission is to be made in the second uplink transmission occasion.

[0094] The following numbered clauses provide further example aspects and features of the present technology: 1. A method of operating an infrastructure equipment forming part of a wireless communications network, the infrastructure equipment being configured to transmit signals to and / or receive signals from communications devices over a wireless access interface, the method comprising: monitoring an uplink channel for a transmission from a communications device during a first uplink transmission occasion; and attempting to decode a transmission from a communications device in the first uplink transmission occasion; and attempting to identify a first retransmission indicator associated with the first uplink transmission occasion; determining whether to schedule uplink resources on the uplink channel for one or more retransmissions of the transmission based on attempting to identify the first retransmission indicator associated with the first uplink transmission occasion, wherein if the infrastructure equipment is unable to identify a retransmission indicator associated with the first uplink transmission occasion, the infrastructure equipment schedules the uplink resources for one or more retransmissions of the first transmission by the communications device that the infrastructure equipment failed to decode.

[0095] 2. The method of clause 1, wherein attempting to decode the transmission comprises attempting to detect one or more demodulation reference signals during the first uplink transmission occasion.

[0096] 3. The method of clause 1 or clause 2, wherein the infrastructure equipment does not detect the transmission during the first uplink transmission occasion.

[0097] 4. The method of clause 3, further comprising determining whether the first uplink transmission occasion comprises a transmission from the communications device that was not successfully decoded by the infrastructure equipment.

[0098] 5. A method according to clause 4, wherein the infrastructure equipment determines whether the first uplink transmission occasion comprises a transmission from the communications device that is not successfully decoded by the infrastructure equipment based on whether an indication is received from the communications device during a transmission occasion preceding the first uplink transmission occasion that the first uplink transmission occasion comprises a first transmission from the communications device.

[0099] 6. A method according to clause 4 or 5, wherein the infrastructure equipment determines whether the first uplink transmission occasion comprises a transmission from the communications device that is not successfully decoded by the infrastructure equipment based on whether an indication is received from the communications device during a transmission occasion preceding the first uplink transmission occasion that a particular uplink transmission occasion configuration of a plurality of uplink transmission occasion configurations comprises any transmission from the communications device, wherein the first uplink transmission occasion has the particular uplink transmission occasion configuration.

[0100] 7. A method according to clause 1 or 2, wherein the infrastructure equipment detects the first transmission during the first uplink transmission occasion.

[0101] 8. A method according to clause 7, further comprising: identifying a first retransmission indicator associated with the first uplink transmission occasion; scheduling uplink resources for the communications device to transmit one or more retransmissions of the first transmission based on determining that the first retransmission indicator indicates that the one or more retransmissions of the first transmission are to be performed.

[0102] 9. A method according to clause 7, further comprising: identifying a first retransmission indicator associated with the first uplink transmission occasion; determining not to schedule uplink resources for the communications device to transmit one or more retransmissions of the first transmission based on determining that the first retransmission indicator indicates that the one or more retransmissions of the first transmission are not to be performed.

[0103] 10. A method according to any of clauses 7 to 9, wherein the infrastructure equipment identifies the first retransmission indicator based on receiving the first retransmission indicator in the first transmission.

[0104] 11. A method according to any of clauses 7 to 10, wherein the first transmission comprises a second retransmission indicator for a second transmission occasion occurring after the first transmission occasion.

[0105] 12. A method according to any of clauses 7 to 11, wherein the first transmission comprises a third retransmission indicator for a third transmission occasion occurring before the first transmission occasion.

[0106] 13. A method according to Clause 12, further comprising determining a modification to one or more transmission parameters of the communications device based on the third retransmission indicator and whether a transmission is detected during the third transmission occasion.

[0107] 14. A method according to any one of the preceding Clauses, further comprising identifying the first retransmission indicator associated with the first uplink transmission occasion based on receiving a retransmission indicator associated with the first uplink transmission occasion from the communications device during a transmission occasion preceding the first uplink transmission occasion.

[0108] 15. A method according to any one of the preceding Clauses, further comprising identifying the first retransmission indicator associated with the first uplink transmission occasion based on receiving a retransmission indicator associated with a particular uplink transmission occasion configuration of a plurality of uplink transmission occasion configurations from the communications device during a transmission occasion preceding the first uplink transmission occasion, wherein the first uplink transmission occasion has the particular uplink transmission occasion configuration.

[0109] 16. A method according to any one of the preceding Clauses, wherein the indication of the retransmission indicator is comprised in uplink control information received from the communications device.

[0110] 17. A method according to any one of the preceding Clauses, wherein the indication of the retransmission indicator is comprised in a MAC control element (CE) received from the communications device.

[0111] 18. A method according to Clause 16 or Clause 17, wherein the indication of the retransmission indicator is comprised in a physical uplink shared channel transmission.

[0112] 19. A method according to any one of the preceding Clauses, wherein attempting to identify the first retransmission indicator associated with the first uplink transmission occasion comprises deriving a value of the retransmission indicator based on one or more other parameters comprised in uplink control information received from the communications device.

[0113] 20. A method according to Clause 19, wherein the one or more other parameters comprise a HARQ process number (HPN) or an identifier, and wherein the first uplink transmission occasion occurs in unlicensed spectrum.

[0114] 21. Infrastructure equipment comprising: a transceiver configured to transmit signals to and / or receive signals from communications devices over a wireless radio interface provided by the infrastructure equipment, and a controller, in combination with the transceiver, configured to: monitor an uplink channel for a transmission from a communications device during a first uplink transmission occasion; and attempting to decode the transmission from the communications device in the first uplink transmission occasion; and attempting to identify a first retransmission indicator associated with the first uplink transmission occasion; determining, based on attempting to identify the first retransmission indicator associated with the first uplink transmission occasion, whether to schedule uplink resources on the uplink channel for one or more retransmissions of the transmission, wherein the infrastructure equipment is configured to schedule the uplink resources for the communications device to transmit one or more retransmissions of the first transmission that the infrastructure equipment failed to decode if the infrastructure equipment is unable to identify a retransmission indicator associated with the first uplink transmission occasion.

[0115] 22. Circuitry for an infrastructure equipment, the circuitry comprising: transceiver circuitry configured to transmit signals to and / or receive signals from communications devices over a wireless radio interface provided by the infrastructure equipment, and controller circuitry in combination with the transceiver circuitry is configured to: monitor an uplink channel for a transmission from a communications device during a first uplink transmission occasion; and attempt to decode the transmission from the communications device in the first uplink transmission occasion; and attempt to identify a first retransmission indicator associated with the first uplink transmission occasion; determining, based on attempting to identify the first retransmission indicator associated with the first uplink transmission occasion, whether to schedule uplink resources on the uplink channel for one or more retransmissions of the transmission, wherein the infrastructure equipment is configured to schedule the uplink resources for the communications device to transmit one or more retransmissions of the first transmission that the infrastructure equipment failed to decode if the infrastructure equipment is unable to identify a retransmission indicator associated with the first uplink transmission occasion.

[0116] 23. A method of operating a communications device configured to transmit signals to and / or receive signals from an infrastructure equipment of a wireless communications network over a wireless access interface, the method comprising: transmitting, to the infrastructure equipment during a first uplink transmission occasion, an indication of whether a transmission in a second uplink transmission occasion occurring after the first uplink transmission occasion is to be retransmitted.

[0117] 24. The method of clause 23, wherein the indication of whether the transmission in the second uplink transmission occasion is to be retransmitted comprises a retransmission indicator associated with the second uplink transmission occasion.

[0118] 25. A method according to clause 23 or clause 24, wherein the indication of whether the transmission in the second uplink transmission occasion is to be retransmitted comprises an indication of whether the communications device is to use the second uplink transmission occasion for any uplink transmission.

[0119] 26. A method according to any one of clauses 23 to 25, wherein the indication of whether the transmission in the second uplink transmission occasion is to be retransmitted comprises a retransmission indicator associated with a particular uplink transmission occasion configuration of a plurality of uplink transmission occasion configurations, wherein the second uplink transmission occasion has the particular uplink transmission occasion configuration.

[0120] 27. A method according to any one of clauses 23 to 26, wherein the indication of whether the transmission in the second uplink transmission occasion is to be retransmitted comprises an indication of whether the communications device is to use a particular uplink transmission occasion configuration of a plurality of uplink transmission occasion configurations for any uplink transmission, wherein the second uplink transmission occasion has the particular uplink transmission occasion configuration.

[0121] 28. A method according to any one of clauses 23 to 27, wherein the indication indicates that the transmission in the second uplink transmission occasion is to be retransmitted, and wherein the method further comprises: transmitting the first transmission to the infrastructure equipment during the second uplink transmission occasion; receiving a transmission from the infrastructure equipment scheduling uplink resources for retransmission of the first transmission; and retransmitting the first transmission to the infrastructure equipment using the scheduled uplink resources.

[0122] 29. A method according to any one of clauses 23 to 27, wherein the indication indicates that the transmission in the second uplink transmission occasion is not to be retransmitted, and wherein the method further comprises: transmitting the first transmission to the infrastructure equipment during the second uplink transmission occasion; receiving a transmission from the infrastructure equipment scheduling uplink resources for retransmission of the first transmission; and determining not to use the scheduled uplink resources for retransmission of the first transmission.

[0123] 30. A communications device comprising: a transceiver configured to transmit signals to and / or receive signals from an infrastructure equipment of a wireless communications network over a wireless radio interface provided by the wireless communications network, and a controller, in combination with the transceiver, configured to: to transmit to the infrastructure equipment an indication of whether a transmission in a second uplink transmission occasion, which occurs after the first uplink transmission occasion, is to be retransmitted.

[0124] 31. Circuitry for a communications device, comprising: transceiver circuitry configured to transmit and / or receive signals to and / or from an infrastructure equipment of a wireless communications network over a wireless radio interface provided by the wireless communications network, and controller circuitry, in combination with the transceiver circuitry, is configured to: to transmit to the infrastructure equipment an indication of whether a transmission in a second uplink transmission occasion, which occurs after the first uplink transmission occasion, is to be retransmitted.

[0125] Thus, from one perspective, methods, infrastructure equipment and communications devices for robustly signalling whether a particular uplink transmission occasion requires retransmission have been described. The communications device indicates in an earlier uplink occasion whether a particular uplink transmission occasion requires retransmission, and the infrastructure equipment selectively schedules uplink resources for retransmission based on the indication from the communications device. If the infrastructure equipment is unable to determine whether a particular uplink transmission occasion requires retransmission, the infrastructure equipment schedules uplink resources for the particular uplink transmission occasion.

[0126] It will be appreciated that, for clarity, the above description 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 can be used without detracting from the embodiments. For example, functionality illustrated to be performed by separate units, circuitry or processors can be performed by the same unit, circuitry or processor.

[0127] The described embodiments can be implemented in any suitable form including hardware, software, firmware or any combination of these. The described embodiments can 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 implementation can be physically, functionally and logically implemented in any suitable way. Indeed, the functions can be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the disclosed embodiments can be implemented in a single unit or can be physically and functionally distributed between different units, circuitry and / or processors.

[0128] Although the present disclosure has been described in connection with certain embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the disclosure is to cover by the appended claims whatever falls within the scope of the invention. Furthermore, although features could be described as being combined, it will be appreciated that some features can be implemented independently of other features.

[0129] References

[0130] [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[0131] [2] TR 38.913, “Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14)”, third Generation Partnership Project, v14.3.0.

[0132] [3] RP-190726, “Physical layer enhancements for NR ultra-reliable and low latency communication (URLLC)”, Huawei, HiSilicon, RAN#83.

[0133] [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.

[0134] [5] RP-191575, “NR-based Access to Unlicensed Spectrum”, Qualcomm, RAN#84.

[0135] [6] RP-220285, “Revised SID: Study on XR Enhancements for NR”, Nokia, RAN#95e.

[0136] [7] R2-2302309 (TR38.835), “Study on XR enhancements for NR”, v1.0.2.

[0137] [8] TR 38.838, “Study on XR (Extended Reality) Evaluations for NR(Release 17)”, v17.0.0.

[0138] [9] International Patent Application Publication No. WO2022 / 018230.

[0139]

[10] R1-2210002, “Power Saving Techniques for XR”, Qualcomm, RAN1#110bis-e.

Claims

1. A method of operating an infrastructure equipment forming part of a wireless communications network, the infrastructure equipment being configured to transmit signals to and / or receive signals from communications devices over a wireless access interface, the method comprising: monitoring an uplink channel for a transmission from a communications device during a first uplink transmission occasion; attempting to decode the transmission from the communications device in the first uplink transmission occasion; attempting to identify a first retransmission indicator associated with the first uplink transmission occasion; and based on attempting to identify the first retransmission indicator associated with the first uplink transmission occasion, determining whether to schedule uplink resources on the uplink channel for one or more retransmissions of the transmission, wherein if the infrastructure equipment is unable to identify a retransmission indicator associated with the first uplink transmission occasion, the infrastructure equipment schedules uplink resources for the communications device to transmit the one or more retransmissions of the first transmission which the infrastructure equipment failed to decode. attempting to decode the transmission comprises attempting to detect one or more demodulation reference signals during the first uplink transmission occasion.

2. The method of claim 1, wherein, the infrastructure equipment does not detect a transmission during the first uplink transmission occasion.

3. The method of claim 1, wherein, 4. The method of claim 3, further comprising determining whether the first uplink transmission occasion comprises a transmission from the communications device which was unsuccessfully decoded by the infrastructure equipment. based on receiving an indication from the communications device during a transmission occasion preceding the first uplink transmission occasion that the first uplink transmission occasion comprises a first transmission from the communications device, the infrastructure equipment determines whether the first uplink transmission occasion comprises a transmission from the communications device which was unsuccessfully decoded by the infrastructure equipment.

5. The method of claim 4, wherein, based on receiving an indication from the communications device during a transmission occasion preceding the first uplink transmission occasion that a particular uplink transmission occasion configuration of a plurality of uplink transmission occasion configurations comprises any transmission from the communications device, the infrastructure equipment determines whether the first uplink transmission occasion comprises a transmission from the communications device which was unsuccessfully decoded by the infrastructure equipment, wherein the first uplink transmission occasion has the particular uplink transmission occasion configuration.

6. The method of claim 4, wherein, the infrastructure equipment detects a first transmission during the first uplink transmission occasion.

7. The method of claim 1, wherein, 8. The method of claim 7, further comprising: identifying the first retransmission indicator associated with the first uplink transmission occasion; based on determining that the first retransmission indicator indicates that one or more retransmissions of the first transmission are to be performed, scheduling uplink resources for the communications device to transmit the one or more retransmissions of the first transmission.

9. The method of claim 7, further comprising: identifying the first retransmission indicator associated with the first uplink transmission occasion; ​ based on determining that the first retransmission indicator indicates that no retransmission of the first transmission is to be performed, determining not to schedule uplink resources for the communication device to transmit the one or more retransmissions of the first transmission.

10. The method of claim 7, wherein, The infrastructure equipment identifies the first retransmission indicator based on receiving the first retransmission indicator in the first transmission.

11. The method of claim 7, wherein, The first transmission comprises a second retransmission indicator for a second transmission occasion occurring after the first transmission occasion.

12. The method of claim 7, wherein, The first transmission comprises a third retransmission indicator for a third transmission occasion occurring before the first transmission occasion.

13. The method of claim 12, further comprising: based on the third retransmission indicator and whether a transmission during the third transmission occasion is detected, determining a modification to one or more transmission parameters of the communication device.

14. The method of claim 1, further comprising: identifying the first retransmission indicator associated with the first uplink transmission occasion based on receiving the retransmission indicator associated with the first uplink transmission occasion from the communication device during a transmission occasion preceding the first uplink transmission occasion.

15. The method of claim 1, further comprising: identifying the first retransmission indicator associated with the first uplink transmission occasion based on receiving the retransmission indicator associated with a particular uplink transmission occasion configuration of a plurality of uplink transmission occasion configurations from the communication device during a transmission occasion preceding the first uplink transmission occasion, wherein the first uplink transmission occasion has the particular uplink transmission occasion configuration.

16. The method of claim 1, wherein, The indication of the retransmission indicator is comprised in uplink control information received from the communication device.

17. The method of claim 1, wherein, The indication of the retransmission indicator is comprised in a MAC control element (CE) received from the communication device.

18. The method of claim 16, wherein, The indication of the retransmission indicator is comprised in a physical uplink shared channel transmission.

19. The method of claim 1, wherein, The attempting to identify the first retransmission indicator associated with the first uplink transmission occasion comprises deriving a value of the retransmission indicator based on one or more other parameters comprised in uplink control information received from the communication device.

20. The method of claim 19, wherein, The one or more other parameters comprise a HARQ process number (HPN) or an identifier, and wherein the first uplink transmission occasion occurs in unlicensed spectrum.

21. An infrastructure equipment comprising: a transceiver configured to transmit signals to and / or receive signals from a communication device over a wireless radio interface provided by the infrastructure equipment, and a controller configured in combination with the transceiver to: monitor an uplink channel for a transmission from a communication device during a first uplink transmission occasion; attempt to decode the transmission from the communication device in the first uplink transmission occasion; attempt to identify a first retransmission indicator associated with the first uplink transmission occasion; and determining whether to schedule uplink resources on the uplink channel for one or more retransmissions of the transmission based on attempting to identify the first retransmission indicator associated with the first uplink transmission occasion, wherein the infrastructure equipment is configured to schedule uplink resources for the communications device to transmit the one or more retransmissions of the first transmission that the infrastructure equipment failed to decode if the infrastructure equipment is unable to identify a retransmission indicator associated with the first uplink transmission occasion.

22. Circuitry for an infrastructure equipment, the circuitry comprising: transceiver circuitry configured to transmit signals to and / or receive signals from a communications device over a wireless radio interface provided by the infrastructure equipment, and controller circuitry configured in combination with the transceiver circuitry to: monitor an uplink channel for a transmission from a communications device during a first uplink transmission occasion; attempt to decode the transmission from the communications device in the first uplink transmission occasion; attempt to identify a first retransmission indicator associated with the first uplink transmission occasion; and determine whether to schedule uplink resources on the uplink channel for one or more retransmissions of the transmission based on attempting to identify the first retransmission indicator associated with the first uplink transmission occasion, wherein the infrastructure equipment is configured to schedule uplink resources for the communications device to transmit the one or more retransmissions of the first transmission that the infrastructure equipment failed to decode if the infrastructure equipment is unable to identify a retransmission indicator associated with the first uplink transmission occasion.

23. A method of operating a communications device configured to transmit signals to and / or receive signals from an infrastructure equipment of a wireless communications network over a wireless access interface, the method comprising: transmitting, to the infrastructure equipment during a first uplink transmission occasion, an indication of whether a transmission in a second uplink transmission occasion occurring after the first uplink transmission occasion is to be retransmitted.

24. The method of claim 23, wherein, The indication of whether a transmission in a second uplink transmission occasion is to be retransmitted comprises a retransmission indicator associated with the second uplink transmission occasion.

25. The method of claim 23, wherein, The indication of whether a transmission in a second uplink transmission occasion is to be retransmitted comprises an indication of whether the communications device is using the second uplink transmission occasion for any uplink transmission.

26. The method of claim 23, wherein, The indication of whether a transmission in a second uplink transmission occasion is to be retransmitted comprises a retransmission indicator associated with a particular uplink transmission occasion configuration of a plurality of uplink transmission occasion configurations, wherein the second uplink transmission occasion has the particular uplink transmission occasion configuration.

27. The method of claim 23, wherein, whether the transmission in the second uplink transmission occasion is to be retransmitted comprises an indication of whether the communications device is to configure a particular uplink transmission occasion configuration of a plurality of uplink transmission occasion configurations for any uplink transmission, wherein the second uplink transmission occasion has the particular uplink transmission occasion configuration.

28. The method of claim 23, wherein, the indication indicates that the transmission in the second uplink transmission occasion is to be retransmitted, and wherein the method further comprises: transmitting a first transmission to the infrastructure equipment during the second uplink transmission occasion; receiving a transmission from the infrastructure equipment scheduling uplink resources for retransmission of the first transmission; and retransmitting the first transmission to the infrastructure equipment using the scheduled uplink resources.

29. The method of claim 23, wherein, the indication indicates that the transmission in the second uplink transmission occasion is not to be retransmitted, and wherein the method further comprises: transmitting a first transmission to the infrastructure equipment during the second uplink transmission occasion; receiving a transmission from the infrastructure equipment scheduling uplink resources for retransmission of the first transmission; and determining not to use the scheduled uplink resources for retransmission of the first transmission.

30. The method of claim 23, wherein, the indication indicates that the transmission in the second uplink transmission occasion is not to be retransmitted, and wherein the second uplink transmission occasion does not comprise any transmission by the communications device, wherein the method further comprises: receiving a transmission from the infrastructure equipment scheduling uplink resources for retransmission of a first transmission in the second uplink transmission occasion; and determining not to use the scheduled uplink resources for retransmission of the first transmission.

31. A communications device comprising: a transceiver configured to transmit signals to and / or receive signals from an infrastructure equipment of a wireless communications network over a wireless radio interface provided by the wireless communications network, and a controller configured in combination with the transceiver to: transmit, to the infrastructure equipment during a first uplink transmission occasion, an indication of whether a transmission in a second uplink transmission occasion occurring after the first uplink transmission occasion is to be retransmitted.

32. Circuitry for a communications device comprising: a transceiver circuitry configured to transmit signals to and / or receive signals from an infrastructure equipment of a wireless communications network over a wireless radio interface provided by the wireless communications network, and a controller circuitry configured in combination with the transceiver circuitry to: transmit, to the infrastructure equipment during a first uplink transmission occasion, an indication of whether a transmission in a second uplink transmission occasion occurring after the first uplink transmission occasion is to be retransmitted.

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