Methods, communications devices, and infrastructure equipment

Abstract

A method of operating a communications device to communicate with infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment is provided. The radio access interface comprises one or more slots. At least one of the slots is a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed (OFDM) symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink. The method comprises receiving, from the infrastructure equipment, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmitting on the uplink. The method comprises determining that the communications device is to transmit a physical random access channel (PRACH) in a PRACH Occasion (RO) comprising at least some of the disabled uplink communications resources. The method comprises, in response, re-enabling at least the disabled uplink communications resources comprised in the RO for transmitting on the uplink, and transmitting the PRACH in the RO.

Description

[0001] METHODS, COMMUNICATIONS DEVICES, AND INFRASTRUCTURE EQUIPMENT

[0002] BACKGROUND

[0003] Field of Disclosure

[0004] The present disclosure relates to communications devices, infrastructure equipment of a wireless communications network, and methods.

[0005] The present application claims Paris Convention priority from EP application number 24204485.7, filed on 3 October 2024, the contents of which are hereby incorporated by reference in their entirety.

[0006] Description of Related Art

[0007] The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.

[0008] Previous generation mobile telecommunication systems, such as those based on the 3GPP defined UMTS and Long Term Evolution (LTE) architecture, are able to support a wider range of services than simple voice and messaging services offered by previous generations of mobile telecommunication systems. For example, with the improved radio interface and enhanced data rates provided by LTE systems, a user is able to enjoy high data rate applications such as mobile video streaming and mobile video conferencing that would previously only have been available via a fixed line data connection. The demand to deploy such networks is therefore strong and the coverage area of these networks, i.e. geographic locations where access to the networks is possible, is expected to continue to increase rapidly.

[0009] Current and future wireless communications networks are expected to routinely and efficiently support communications with an ever-increasing range of devices associated with a wider range of data traffic profiles and types than existing systems are optimised to support. For example, it is expected future wireless communications networks will be expected to efficiently support communications with devices including reduced complexity devices, machine type communication (MTC) devices, high resolution video displays, virtual reality headsets, extended Reality (XR) and so on. Some of these different types of devices may be deployed in very large numbers, for example low complexity devices for supporting the “The Internet of Things”, and may typically be associated with the transmissions of relatively small amounts of data with relatively high latency tolerance. Other types of device, for example supporting high-definition video streaming, may be associated with transmissions of relatively large amounts of data with relatively low latency tolerance. Other types of device, for example used for autonomous vehicle communications and for other critical applications, may be characterised by data that should be transmitted through the network with low latency and high reliability. A single device type might also be associated with different traffic profiles / characteristics depending on the application(s) it is running. For example, different considerations may apply for efficiently supporting data exchange with a smartphone when it is running a video streaming application (high downlink data) as compared to when it is running an Internet browsing application (sporadic uplink and downlink data) or being used for voice communications by an emergency responder in an emergency scenario (data subject to stringent reliability and latency requirements).

[0010] In view of this there is expected to be a desire for current wireless communications networks, for example those which may be referred to as 5G or new radio (NR) systems / new radio access technology (RAT) systems, or indeed future 6G wireless communications, as well as future iterations / releases of existing systems, to efficiently support connectivity for a wide range of devices associated with different applications and different characteristic data traffic profiles and requirements. SUMMARY OF THE DISCLOSURE

[0011] The present disclosure can help address or mitigate at least some of the issues discussed above.

[0012] Various aspects and features of the present disclosure are defined in the appended claims.

[0013] It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the present technology. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein like reference numerals designate identical or corresponding parts throughout the several views, and wherein:

[0016] Figure 1 schematically represents some aspects of an LTE-type wireless telecommunication system which may be configured to operate in accordance with certain embodiments of the present disclosure;

[0017] Figure 2 schematically represents some aspects of a new radio access technology (RAT) wireless telecommunications system which may be configured to operate in accordance with certain embodiments of the present disclosure;

[0018] Figure 3 is a schematic block diagram of an example infrastructure equipment and communications device which may be configured to operate in accordance with certain embodiments of the present disclosure;

[0019] Figure 4 schematically represents a first example of non-overlapping sub-bands for uplink and downlink transmissions for sub-band full duplex (SBFD);

[0020] Figure 5 schematically represents second and third examples of non-overlapping sub-bands for uplink and downlink transmissions for SBFD;

[0021] Figure 6 is a schematic representation of a configuration of a TDD slot format and a sub-band full duplex (SBFD) symbol configuration;

[0022] Figure 7 is a schematic representation of a slot configured for SBFD illustrating a collision on the uplink and the downlink;

[0023] Figure 8 is a schematic representation providing an example in which a dynamically configured uplink transmission on a physical uplink shared Channel (PUSCH) collide with a semi-persistent signaled (SPS) resource;

[0024] Figure 9 is a schematic representation of slots including SBFD configured slots in which a conflict or collision occurs between downlink and uplink transmission;

[0025] Figure 10 schematically illustrates examples of SBFD ROs and non-SBFD ROs;

[0026] Figures 11A to 1 ID schematically illustrates valid and invalid ROs;

[0027] Figure 12 schematically illustrates the use of a link direction indicator;

[0028] Figure 13 schematically illustrates a collision between a PDSCH and SBFD RO;

[0029] Figure 14 is a flow diagram illustrating a method of operating a communications device in accordance with example embodiments;

[0030] Figure 15 schematically illustrates an example of re-enabling disabled uplink communications resources in an RO in accordance with example embodiments;

[0031] Figure 16 schematically illustrates an example of only re-enabling disabled uplink communications resources in an RO in accordance with example embodiments;

[0032] Figure 17 schematically illustrates an example of a PRACH, PUSCH and PDSCH collision in an SBFD slot with UL subband disabled in accordance with example embodiments. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Long Term Evolution Advanced Radio Access Technology (4G)

[0034] Figure 1 provides a schematic diagram illustrating some basic functionality of a mobile telecommunications network / system 6 operating generally in accordance with LTE principles, but which may also support other radio access technologies, and which may be adapted to implement embodiments of the disclosure as described herein. Various elements of Figure 1 and certain aspects of their respective modes of operation are well-known and defined in the relevant standards administered by the 3GPP (RTM) body, and also described in many books on the subject, for example, Holma H. and Toskala A [1], It will be appreciated that operational aspects of the telecommunications networks discussed herein which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to the relevant standards and known proposed modifications and additions to the relevant standards.

[0035] The network 6 includes a plurality of base stations 1 connected to a core network 2. Each base station provides a coverage area 3 (i.e. a cell) within which data can be communicated to and from communications devices 4. Although each base station 1 is shown in Figure 1 as a single entity, the skilled person will appreciate that some of the functions of the base station may be carried out by disparate, inter-connected elements, such as antennas (or antennae), remote radio heads, amplifiers, etc. Collectively, one or more base stations may form a radio access network.

[0036] Data is transmitted from base stations 1 to communications devices 4 within their respective coverage areas 3 via a radio downlink (DL). Data is transmitted from communications devices 4 to the base stations 1 via a radio uplink (UL). The core network 2 routes data to and from the communications devices 4 via the respective base stations 1 and provides functions such as authentication, mobility management, charging and so on. Communications devices may also be referred to as mobile stations, user equipment (UEs), user terminals, mobile radios, mobile terminals, terminal devices, wireless transmit and receive units (WTRUs), and so forth. Services provided by the core network 2 may include connectivity to the internet or to external telephony services. The core network 2 may further track the location of the communications devices 4 so that it can efficiently contact (i.e. page) the communications devices 4 for transmitting downlink data towards the communications devices 4.

[0037] Base stations, which are an example of network infrastructure equipment, may also be referred to as transceiver stations, nodeBs, e-nodeBs, eNB, g-nodeBs, gNB and so forth. In this regard different terminology is often associated with different generations of wireless telecommunications systems for elements providing broadly comparable functionality. However, certain embodiments of the disclosure may be equally implemented in different generations of wireless telecommunications systems, and for simplicity certain terminology may be used regardless of the underlying network architecture. That is to say, the use of a specific term in relation to certain example implementations is not intended to indicate these implementations are limited to a certain generation of network that may be most associated with that particular terminology.

[0038] New Radio Access Technology (5G)

[0039] Systems incorporating NR technology are expected to support different services (or types of services), which may be characterised by different requirements for latency, data rate and / or reliability. For example, Enhanced Mobile Broadband (eMBB) services are characterised by high capacity with a requirement to support up to 20 Gb / s. The requirements for Ultra Reliable and Low Latency Communications (URLLC) services are for one transmission of a 32 byte packet to be transmitted from the radio protocol layer 2 / 3 SDU ingress point to the radio protocol layer 2 / 3 SDU egress point of the radio interface within 1 ms with a reliability of 1 - 10'5(99.999 %) or higher (99.9999%) [2],

[0040] Massive Machine Type Communications (mMTC) is another example of a service which may be supported by NR-based communications networks. In addition, systems may be expected to support further enhancements related to Industrial Internet of Things (IIoT) in order to support services with new requirements of high availability, high reliability, low latency, and in some cases, high-accuracy positioning.

[0041] An example configuration of a wireless communications network which uses some of the terminology proposed for and used in NR and 5G is shown in Figure 2. In Figure 2 a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 41, 42 by a connection interface represented as a line 16. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within a radio frequency bandwidth available to the wireless communications network. Thus, within a range for performing radio communications via the wireless access interface, each of the TRPs 10, forms a cell of the wireless communications network as represented by a circle 12. As such, wireless communications devices 14 which are within a radio communications range provided by the cells 12 can transmit and receive signals to and from the TRPs 10 via the wireless access interface. Each of the distributed units 41, 42 are connected to a central unit (CU) 40 (which may be referred to as a controlling node) via an interface 46. The central unit 40 is then connected to the core network 20 which may contain all other functions required to transmit data for communicating to and from the wireless communications devices and the core network 20 may be connected to other networks 25.

[0042] The elements of the wireless access network shown in Figure 2 may operate in a similar way to corresponding elements of an LTE network as described with regard to the example of Figure 1. It will be appreciated that operational aspects of the telecommunications network represented in Figure 2, and of other networks discussed herein in accordance with embodiments of the disclosure, which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to currently used approaches for implementing such operational aspects of wireless telecommunications systems, e.g. in accordance with the relevant standards.

[0043] The TRPs 10 of Figure 2 may in part have a corresponding functionality to a base station or eNodeB of an LTE network. Similarly, the communications devices 14 may have a functionality corresponding to the UE devices 4 known for operation with an LTE network. It will be appreciated therefore that operational aspects of a new RAT network (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be different to those known from LTE or other known mobile telecommunications standards. However, it will also be appreciated that each of the core network component, base stations and communications devices of a new RAT network will be functionally similar to, respectively, the core network component, base stations and communications devices of an LTE wireless communications network.

[0044] In terms of broad top-level functionality, the core network 20 connected to the new RAT telecommunications system represented in Figure 2 may be broadly considered to correspond with the core network 2 represented in Figure 1, and the respective central units 40 and their associated distributed units / TRPs 10 may be broadly considered to provide functionality corresponding to the base stations 1 of Figure 1. The term network infrastructure equipment / access node may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may he with the controlling node / central unit and / or the distributed units / TRPs. A communications device 14 is represented in Figure 2 within the coverage area of the first communication cell 12. This communications device 14 may thus exchange signalling with the first central unit 40 in the first communication cell 12 via one of the distributed units / TRPs 10 associated with the first communication cell 12.

[0045] It will further be appreciated that Figure 2 represents merely one example of a proposed architecture for a new RAT based telecommunications system in which approaches in accordance with the principles described herein may be adopted, and the functionality disclosed herein may also be applied in respect of wireless telecommunications systems having different architectures.

[0046] Thus, certain embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems / networks according to various different architectures, such as the example architectures shown in Figures 1 and 2. It will thus be appreciated the specific wireless telecommunications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, certain embodiments of the disclosure may be described generally in the context of communications between network infrastructure equipment / access nodes and a communications device, wherein the specific nature of the network infrastructure equipment / access node and the communications device will depend on the network infrastructure for the implementation at hand. For example, in some scenarios the network infrastructure equipment / access node may comprise a base station, such as an LTE- type base station 1 as shown in Figure 1 which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment may comprise a control unit / controlling node 40 and / or a TRP 10 of the kind shown in Figure 2 which is adapted to provide functionality in accordance with the principles described herein.

[0047] A more detailed diagram of some of the components of the network shown in Figure 2 is provided by Figure 3. In Figure 3, a TRP 10 as shown in Figure 2 comprises, as a simplified representation, a wireless transmitter 30, a wireless receiver 32 and a controller or controlling processor 34 which may operate to control the transmitter 30 and the wireless receiver 32 to transmit and receive radio signals to one or more UEs 14 within a cell 12 formed by the TRP 10. As shown in Figure 3, an example UE 14 is shown to include a corresponding transmitter 49, a receiver 48 and a controller 44 which is configured to control the transmitter 49 and the receiver 48 to transmit signals representing uplink data to the wireless communications network via the wireless access interface formed by the TRP 10 and to receive downlink data as signals transmitted by the transmitter 30 and received by the receiver 48 in accordance with the conventional operation.

[0048] The transmitters 30, 49 and the receivers 32, 48 (as well as other transmitters, receivers and transceivers described in relation to examples and embodiments of the present disclosure) may include radio frequency filters and amplifiers as well as signal processing components and devices in order to transmit and receive radio signals in accordance for example with the 5G / NR standard. The controllers 34, 44 (as well as other controllers described in relation to examples and embodiments of the present disclosure) may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc., configured to carry out instructions which are stored on a computer readable medium, such as a non-volatile memory. The processing steps described herein may be carried out by, for example, a microprocessor in conjunction with a random access memory, operating according to instructions stored on a computer readable medium. The transmitters, the receivers and the controllers are schematically shown in Figure 3 as separate elements for ease of representation. However, it will be appreciated that the functionality of these elements can be provided in various different ways, for example using one or more suitably programmed programmable computer(s), or one or more suitably configured application-specific integrated circuit(s) / circuitry / chip(s) / chipset(s). As will be appreciated the infrastructure equipment / TRP / base station as well as the UE / communications device will in general comprise various other elements associated with its operating functionality.

[0049] As shown in Figure 3, the TRP 10 also includes a network interface 50 which connects to the DU 42 via a physical interface 16. The network interface 50 therefore provides a communication link for data and signalling traffic from the TRP 10 via the DU 42 and the CU 40 to the core network 20.

[0050] The interface 46 between the DU 42 and the CU 40 is known as the Fl interface which can be a physical or a logical interface. The Fl interface 46 between CU and DU may operate in accordance with specifications 3GPP TS 38.470 and 3GPP TS 38.473, and may be formed from a fibre optic or other wired or wireless high bandwidth connection. In one example the connection 16 from the TRP 10 to the DU 42 is via fibre optic. The connection between a TRP 10 and the core network 20 can be generally referred to as a backhaul, which comprises the interface 16 from the network interface 50 of the TRP 10 to the DU 42 and the Fl interface 46 from the DU 42 to the CU 40.

[0051] In order for a UE such as UE 4 or 14 to transmit uplink data to the network (e.g. on a Physical Uplink Control Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH)) to, for example, base station 1 or TRP 10, the UE must first ensure it is synchronised with the network on the uplink. Since a particular eNB or gNB expects to be receiving communications from many UEs, it needs to ensure that it shares a common timing understanding with each of these UEs (i.e. they are synchronised in terms of the starting times of frames and Orthogonal Frequency Division Multiplexing (OFDM) symbols (often referred to simply as “symbols” for brevity)). This is so that the eNB is able to schedule communication with each of them in a manner that avoids collisions and to ensure orthogonality of the uplink signals, such that intersubcarrier interference is avoided or mitigated.

[0052] Although reference is made to 5G networks, the discussions in this specification apply equally to 6G networks (and beyond) where there is expected to be significantly higher throughput, lower latency and higher reliability utilising sub-THz frequencies.

[0053] Full Duplex Time Division Duplex (FD-TDD)

[0054] NR / 5G networks can operate using Time Division Duplex (TDD), where an entire frequency band or carrier is switched to either downlink or uplink transmissions for a time period and can be switched to the other of downlink or uplink transmissions at a later time period. Currently, TDD operates in Half Duplex mode (HD-TDD) where the gNB or UE can, at a given time, either transmit or receive packets, but not both at the same time. As wireless networks transition from NR to 5G-Advanced networks, a proposed new feature of such networks is to enhance duplexing operation for Time Division Duplex (TDD) by enabling Full Duplex operation in TDD (FD-TDD) [3], [4],

[0055] In FD-TDD, a gNB can transmit and receive data to and from the UEs at the same time on the same frequency band. In addition, a UE can operate either in HD-TDD or FD-TDD mode, depending on its capability. For example, when UEs are only capable of supporting HD-TDD, FD-TDD is achieved at the gNB by scheduling a DL transmission to a first UE and scheduling an UL transmission from a second UE within the same OFDM symbol (i.e. at the same time). Conversely, when UEs are capable of supporting FD-TDD, FD-TDD is achieved both at the gNB and the UE, where the gNB can simultaneously schedule this UE with DL and UL transmissions within the same OFDM symbol by scheduling the DL and UL transmissions at different frequencies (e.g. physical resource blocks (PRBs)) of the system bandwidth. A UE supporting FD-TDD requires more complex hardware than a UE that only supports HD-TDD. Development of current 5G networks is focused primarily on enabling FD-TDD at the gNB with UEs operating in HD-TDD mode.

[0056] Motivations for enhancing duplexing operation for TDD include an improvement in system capacity, reduced latency, and improved uplink coverage. For example, in current HD-TDD systems, OFDM symbols are allocated only for either a DL or UL direction in a semi-static manner. Hence, if one direction experiences less or no data, the spare resources cannot be used in the other direction, or are, at best, underutilised. However, if resources can be used for DL data and UL data (as in FD-TDD) at the same time, the resource utilisation in the system can be improved. Furthermore, in current HD-TDD systems, a UE can receive DL data, but cannot transmit UL data at the same time, which causes delays. If a gNB or UE is allowed to transmit and receive data at the same time (as with FD-TDD), the traffic latency will be improved. In addition, UEs are usually coverage limited in their UL transmissions when located close to the edge of a cell. While the UE coverage at the cell-edge can be improved if more time domain resources are assigned to UL transmissions (e.g. repetitions), for HD-TDD systems, if the UL direction is assigned more time resources, fewer time resources can be assigned to the DL direction, which can lead to system imbalance. In contrast, in FD-TDD, continuous UL resources can be assigned for repetition opportunities whilst allowing DL traffic to occur in those resources, thereby UL enhancing coverage without causing system imbalance.

[0057] A Rel-19 Work Item (WI) [5] on Duplex Evolution is therefore agreed to specify the requirements for FD- TDD. In Rel-19 Duplex Evolution, FD-TDD is performed at the gNB, where the gNB can transmit and receive data / signals to / from the UEs at the same time on the same frequency band, whilst the UE is maintained as HD-TDD. That is, full duplex TDD is achieved at the gNB by scheduling a UE in the DL and scheduling another UE in the UL within the same OFDM symbol. One of the objectives of the Rel-19 Duplex Evolution WI [5] is to support RACH operation in Sub-band Full Duplex (SBFD) OFDM symbols.

[0058] Sub-band Full Duplex (SBFD)

[0059] In SBFD, the frequency resource of a TDD system bandwidth or Bandwidth Part (BWP) (i.e. at the UE / gNB) is divided into two or more non-overlapping sub-bands, where each sub-band can be DL or UL [6], Guard sub-bands may be used between DL and UL sub-bands to reduce inter sub-band interference. In the current 5G system, only one UL sub-band can be configured in an OFDM symbol.

[0060] An example is shown in Figure 4, where simultaneous DL and UL transmissions occur in three different non-overlapping sub-bands 61 to 63, i.e. in different sets of frequency Resource Blocks (RB): Sub-band# 1

[0061] 61, Sub-band#2 62, Sub-band#3 63. The example of Figure 4 is referred to as {DUD}, because two subbands, Sub-band# 1 61 and Sub-band#3 63, are used for DL transmissions whilst one sub-band, Sub-band#2

[0062] 62, is used for UL transmissions. To reduce leakage from one sub-band 61 to 63 to another, a guard subband 64 may be configured between UL and DL sub-bands 61 to 63. Guard sub-bands 64 are configured between DL Sub-band#3 63 and UL Sub-band#2 62 and between UL Sub-band#2 62 and DL Sub-band# 1 61.

[0063] Figure 5 shows two further examples with a DL and UL sub-band separated by a guard sub-band, where here, the UL sub-band can be configured to occupy the lower frequency portion of the BWP whilst the DL sub-band occupies higher frequency portion of the BWP {UD} or the UL sub-band occupies the higher frequency portion of the BWP whilst the DL sub-band occupies lower frequency portion of the BWP {DU} . Here, on the left-side of Figure 5, an UL sub-band# 1 71 is separated from a DL sub-band#2 73 by a guard sub-band 72 - this sub-band arrangement is referred to as {UD}. In this case, the DL sub-band#2 73 occupies a higher frequency portion of the system bandwidth than the UL sub-band# 1 71. On the rightside of Figure 5, a DL sub-band# 1 81 is separated from an UL sub-band#2 83 by a guard sub-band 82 - this sub-band arrangement is referred to as {DU}. In this case, the UL sub-band#2 83 occupies a higher frequency portion of the system bandwidth than the DL sub-band# 1 81.

[0064] While Figures 4 and 5 show the system bandwidth as being divided into either two or three sub-bands, those skilled in the art would appreciate that the concept of SBFD may (in further releases of the 3GPP specifications, for example) be extended such that any number of sub-bands could be used, if deemed beneficial. In one example, the system bandwidth may be divided into four sub-bands. For example, a system bandwidth may include the two downlink sub-bands 61, 63, and the uplink sub-band 62 shown in Figure 4, and another uplink sub-band (not shown), though other sub-band arrangements (e.g. number and size of UL and SL subbands) are possible. Guard sub-bands may be used in substantially any sub-band arrangement.

[0065] SBFD Configuration

[0066] In a legacy TDD system, an OFDM symbol can be configured as Downlink (DL), Uplink (UL) or Flexible (FL). DL OFDM symbols can be used by the gNB to transmit downlink transmissions to the UE whilst UL OFDM symbols can be used by the UE to transmit uplink transmissions to the gNB. FL OFDM symbols can be later configured into either DL or UL OFDM symbols.

[0067] In Release- 19 (Rel-19), In addition to DL, UL and FL OFDM symbols, SBFD OFDM symbols are introduced. SBFD OFDM symbols may comprise resources from one or more uplink subbands and one or more downlink subbands. For example, an SBFD OFDM symbol may comprise one UL sub-band and either one or two DL sub-bands as shown in Figures 4 and 5, for example. In Rel-19, SBFD OFDM symbols are semi-statically configured, where SBFD OFDM symbols can be configured on DL OFDM symbols and / or FL OFDM symbols that are cell-specifically configured. One of the objectives of Duplex Evolution is to increase UL capacity and so at least for Rel-19, SBFD is only configured in DL and / or FL OFDM symbols, i.e., by configuring a UL sub-band in DL and / or FL OFDM symbols. That is, DL OFDM symbols and FL OFDM symbols configured cell specifically using the parameter TDD-UL-DL- ConfigCommon, can be further semi-statically configured into SBFD OFDM symbols using a new RRC configuration message. DL, UL and FL OFDM symbols configured using TDD-UL-DL-ConfigCommon are termed herein as original DL, UL and FL OFDM symbols respectively.

[0068] An example is shown in Figure 6, where a TDD Slot Format {DDDSU}, consisting of three DL slots, one slot with DL and FL OFDM symbols, and one UL slot is, cell specifically configured 701 using the RRC parameter TDD-UL-DL-ConfigCommon. In this example, Slot n+1 and Slot w+2. which consist of original DL OFDM symbols, and Slot n+3, which consists of original DL and original FL OFDM symbols, are configured (e.g., by another RRC configuration 702 which can be another cell specific configuration or UE specific configuration) into SBFD OFDM symbols with a {DUD} sub-band arrangement - as shown by the black dashed boxes in Figure 6. In Rel-19, original UL OFDM symbols, i.e., UL OFDM symbols configured via TDD-UL-DL-ConfigCommon, are not used for configuration of SBFD OFDM symbols as described above.

[0069] In Rel-19, SBFD OFDM symbol configuration is not dynamically configured to reduce complexity in managing CLI among gNBs. Hence, an original DL or FL OFDM symbol that is configured as SBFD OFDM symbol such as in the example of Figure 6 cannot be dynamically configured back to non-SBFD OFDM symbols. Downlink and Uplink Collisions

[0070] An SBFD UE may be scheduled with simultaneous DL reception and UL transmission in SBFD OFDM symbols, resulting in a collision since the SBFD UE is half duplex, i.e., it cannot receive and transmit at the same time. An example is shown in Figure 7, which provides a schematic representation of a slot comprising fourteen OFDM symbols 800, which are divided into sub-bands for uplink 802 and downlink 804 transmission according to an SBFD arrangement. As shown in Figure 7, an SBFD UE is configured with periodically occurring SPS (Semi-persistent Scheduling) PDSCH 806 in the DL and CG-PUSCH 808 in the UL. At some point in time, these two semi-statically configured transmissions collide 810 where the CG-PUSCH occasion is in the UL subband and the SPS is in the DL subband.

[0071] For the case where the DL and UL collision consists of a dynamically scheduled channel and a semi- statically configured channel, the dynamically scheduled channel has priority and is transmitted / received whilst the semi-statically configured channel is dropped. An example is shown in Figure 8, where the gNB configures an SBFD UE with a periodically occurring SPS. In Slot n, the gNB transmits an UL Grant 900 to schedule a PUSCH in Slot «+l, as represented by an arrow 902, where the UE is also configured for an SPS 904 thereby causing a DL and UL collision, as represented by an “X” 906. In this case, since the PUSCH is dynamically scheduled, the UE drops the semi-statically configured SPS 904 and transmits the PUSCH 908. This assumes that the gNB is aware of the semi-statically configured channel and if the gNB deliberately schedules a dynamic DL or UL to collide with a semi-static channel, then the UE should follow the latest instruction from the gNB and so the dynamic DL / UL channel has priority.

[0072] For the DL and UL collision cases where, both the DL and UL channels are dynamically scheduled and are non-repetitive, this is considered an error case. That is the UE behaviour is unspecified and it is up to gNB to avoid scheduling such collision. An example is shown in Figure 9, in which five slots n to n+4 are shown for an SBFD configuration, where in Slot n, the gNB transmits a DL Grant 1001 to the UE to schedule a PDSCH 1002 in Slot n+3, as represented by an arrow 1004. Later in Slot n+2, the gNB transmits a UL Grant 1011 to the UE to schedule a PUSCH 1012 in Slot n+3, represented by an arrow 1014, thereby causing a DL and UL collision between the dynamically scheduled PDSCH and dynamically scheduled PUSCH. This is an error case and the UE behaviour is unspecified as the UE does not expect such collision, which is represented in Figure 9 as an “?”.

[0073] A DL & UL collision where both channels are semi-statically configured is also considered as an error case. For example, in Figure 9, the SBFD UE is configured with CG-PUSCH and SPS, and in Slot n+1, both CG-PUSCH and SPS occasions collide in time. The SBFD UE does not expect such collisions and hence its behaviour is unspecified, which is represented in Figure 9 as an “?”. It is up to the gNB to avoid such configurations. Hence, the collision can be avoided by gNB implementation.

[0074] PRACH Occasions

[0075] As will be understood by a person skilled in the art, a Physical Random Access (PRACH) configuration comprises a plurality of PRACH Occasions (RO) configured in uplink communications resources of a wireless access interface. The ROs in a PRACH configuration may be periodically repeating. The ROs represent transmission opportunities for a UE to transmit a PRACH. Each RO may be configured to support up to 64 preambles. In this case, each RO may support a PRACH transmission of up to 64 UEs if each UE uses a different preamble for its PRACH transmission. The ROs may be Frequency Division Multiplexed (FDM) where infrastructure equipment of a wireless communications network can configure { 1, 2, 4, 8} FDM ROs for UEs. The start of the first RO may be indicated by the network using the RRC parameter msgl -FrequencyStart, and the remaining ROs are sequentially mapped one after the other in frequency domain. As mentioned above, ROs are configured in communications resources of a wireless access interface. Communications resources are comprised of time resources and frequency resources. The time resources of the ROs in a PRACH Occasion configuration are determined by a “PRACH Configuration Index”, which is an index to Tables 6.3.3.2-2, 6.3.3.2-3 and 6.3.3.2-4 in [7], which is hereby incorporated by reference in its entirety. There are 256, 263 and 256 PRACH configurations for FR1 FDD, FR1 TDD and FR2 respectively. The PRACH configuration index indicates a PRACH preamble format, a PRACH periodicity (known as a “PRACH Configuration Period”), a number of PRACH Occasions within a PRACH period, the starting symbol of the PRACH Occasion in a slot, and a duration of the PRACH Occasion.

[0076] In Rel-19, ROs can be configured in the UL subbands of SBFD OFDM symbols. ROs which are contained within SBFD OFDM symbols may be referred to as “SBFD ROs”. SBFD ROs increase PRACH opportunities for SBFD UEs. An example is shown in Figure 10, where Slot n and Slot n+1 are SBFD slot and UL slot respectively. As shown in Figure 10, SBFD slot n comprises four SBFD ROs labelled RO#1, RO#2, RO#3 and RO#4. Furthermore, non-SBFD slot n+1 is an UL slot comprising four non-SBFD ROs labelled as Legacy RO#5, RO#6, RO#7 and RO#8, which are configured for legacy UEs. Legacy ROs and legacy UEs may alternatively be referred to as non-SBFD ROs and non-SBFD UEs respectively. UEs that are capable of SBFD therefore can use the legacy ROs and SBFD ROs thereby increasing its RACH opportunity.

[0077] Valid ROs Determination

[0078] For FDD all configured ROs are valid. However, for TDD, the following three legacy validity conditions must be met for an RO to be valid:

[0079] • A valid RO is contained fully in UL OFDM symbols since PRACH cannot be transmitted in DL OFDM symbols;

[0080] • In addition to being fully contained in UL OFDM symbols, there also needs to be a gap of NgapOFDM symbols between the end of an SSB and the start of the valid RO. The value of Ngapdepends on the subcarrier spacing of the PRACH and it is defined in [8], the contents of which are hereby incorporated by reference in their entirety; and

[0081] • If an RO and an SSB falls within a PRACH slot, the RO is invalid if it precedes the SSB.

[0082] Examples of valid and invalid ROs are shown in Figures 11A to 1 ID. The valid RO shown in Figure 11 A meets all three validity conditions as detailed above. However, the invalid ROs as shown in Figures 9B, 9C, and 9D each fail to meet one of these validity conditions. The RO of Figure 1 IB is invalid because it falls within DL OFDM symbols. The RO of Figure 11C is invalid because there is an insufficient gap between the SSB and the RO. The RO of Figure 1 ID is invalid because the RO precedes the SSB within the PRACH slot.

[0083] An SBFD RO is an RO which is partially or fully contained in SBFD OFDM symbols. An SBFD RO may be regarded as valid if the following conditions are met:

[0084] • The RO is at least partially contained within a UL subband. For example, a part of the RO (e.g. start or end) is in the UL subband of SBFD OFDM symbols and the other part of the RO (if any) is contained within UL OFDM symbols. In a particular example, the RO may start in a UL subband and end in UL OFDM symbols or start in UL OFDM symbols and end in a UL subband. Alternatively, the network may configure that, for an RO to be considered valid, it must be fully contained within an UL subband;

[0085] • The does not overlap in frequency with an SSB; • The RO starts at least Ngap OFDM symbols after the end of a DL OFDM symbol; and

[0086] • The RO starts at least Ngap OFDM symbols after the end of an SSB

[0087] Once the valid ROs are determined, they are indexed in the following order:

[0088] 1. First, in increasing order of preamble indexes within a single RO;

[0089] 2. Second, in increasing order of frequency resource indexes for frequency multiplexed RO;

[0090] 3. Third, in increasing order of time resource indexes for time multiplexed PRACH occasions within a PRACH slot; and

[0091] 4. Fourth, in increasing order of indexes for PRACH slots.

[0092] SSB-RO association is then performed on the indexed valid ROs as will be appreciated by one skilled in the art. Further details of SSB-RO association may be found in [8], the contents of which are hereby incorporated by reference in their entirety. Even further detail on SSB-RO association may be found in our co-pending European patent application number 24155834.5, filed on 5 February 2024, the contents of which are hereby incorporated by reference in their entirety.

[0093] Technical Challenges

[0094] Link Direction Indicator

[0095] As explained above, error cases may arise when DL and UL transmissions collide, and the DL and UL transmissions are both either dynamically or semi-statically scheduled. To address this, a link direction indicator has been proposed [9], The link direction indictor indicates the direction of SBFD symbols. In other words, the gNB indicates whether a UE is allowed to transmit in an UL subband of one or more SBFD OFDM symbols or receive in DL subband(s) of one or more SBFD OFDM symbols. The link direction indicator is expected to be semi-statically configured per UE.

[0096] An example is shown in Figure 12, where an SBFD slot format is configured as {XXXXU} and link directions for Slot n+1 and Slot n+3 are semi-statically configured as UL and DL respectively for a UE. As shown in Figure 12, the link direction indicator directs the UE to disable the DL subbands in Slot n+1. Accordingly, in Slot n+1, the UE can transmit in the uplink subband but cannot receive in the downlink subbands. Furthermore, as shown in Figure 12, the link direction indicator directs the UE to disable the UL subband in slot n+3. Accordingly, in slot n+3, the UE can receive in the DL subbands but cannot transmit in the UL subband. In Slot n+1, SPS#1 is sent to the UE followed by a dynamic PUSCH, but since the DL subbands are disabled, the UE drops SPS#1 and transmits the PUSCH. In Slot n+3, the UE is sent SPS#2 and CG-PUSCH, and similarly the UE drops the CG-PUSCH and receives SPS#2.

[0097] DL and SBFD Valid RO Collision

[0098] One of the DL-UL collisions in a UE is DL reception such as PDSCH colliding with a SBFD RO, as shown in Figure 13. In existing systems, the valid RO is prioritized over DL reception, since in a TDD system the valid RO is expected to reside in UL OFDM symbols only and DL reception is not expected. However, for Half Duplex FDD UE, in the existing specification, it is up to UE implementation whether to receive DL or transmit PRACH. It has been argued that, in the case of SBFD, relying on UE implementation to resolve this collision is not beneficial, since the gNB may trigger a RACH process via PDCCH order which expects the UE to perform PRACH transmissions

[0010] ,

[0099] The RACH process may be used in high priority scenarios which are important to maintain the radio link between the gNB and UE such as beam management, radio link failure and timing synchronisation. Accordingly, it has been suggested that such RACH processes have higher priority over DL reception. It is proposed in

[0010] and

[0011] that the UE prioritises the valid RO over DL reception, if the UE has PRACH to transmit in that RO. It is assumed that the UE would prioritise DL reception if it has no PRACH transmission.

[0100] As mentioned above, the link direction indicator is expected to be semi-statically configured per UE (not all users in the cell-wide), and hence it cannot react to any dynamic changes quickly. That is, if an UL subband is disabled, it will be remain disabled until the next RRC reconfiguration to enable it. During such time the UE is unable to transmit UL in the SBFD OFDM symbols that have their UL subband disabled. Hence if an RO is in a disabled UL subband then it cannot be used for PRACH transmission. Accordingly, important RACH process (such as those required for beam management, radio link failure and timing synchronisation) may be delayed, thus impairing radio link performance and reducing communications efficiency.

[0101] In view of the above, there is provided a method of operating a communications device to communicate with infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment as illustrated in Figure 14.

[0102] The radio access interface comprises one or more slots. At least one of the slots is a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed (OFDM) symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink.

[0103] As will be understood by a person skilled in the art, the uplink is a direction of transmission from the communications device to the infrastructure equipment and the downlink is a direction of transmission from the infrastructure equipment to the communications device. In other words, the communications device transmits on the uplink to the infrastructure equipment and receives on the downlink from the infrastructure equipment whereas the infrastructure equipment transmits on the downlink to the communications device and receives on the uplink from the communications device.

[0104] The method starts at step S1400.

[0105] At step S1410, the method comprises receiving, from the infrastructure equipment, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmitting on the uplink.

[0106] At step S1420, the method comprises determining that the communications device is to transmit a physical random access channel (PRACH) in a PRACH Occasion (RO) comprising at least some of the disabled uplink communications resources.

[0107] In some embodiments, the RO is entirely comprised of the at least some of the disabled uplink communications resources. In some embodiments, the RO comprises the at least some of the disabled uplink communications resources and also comprises other uplink communications resources. In some embodiments, the other uplink communications resources are comprised in an UL slot adjacent to the at least one SBFD slot.

[0108] At step S1430, in response to the determination that the communications device is to transmit a PRACH in an RO comprising at least some of the disabled uplink communications resources, the method comprises re-enabling at least the disabled uplink communications resources comprised in the RO for transmitting on the uplink.

[0109] At step S1440, the method comprises transmitting the PRACH in the RO. The method ends at step S1450.

[0110] By re-enabling the disabled uplink communications resources in response to the determination that the communications device is to transmit a PRACH in an RO comprising at least some of the disabled uplink communications resources, the communications device can transmit the PRACH in the RO. Therefore, the communications device can autonomously override the link direction indicator received from the infrastructure equipment for the PRACH transmission. Therefore, PRACH transmissions can be transmitted even when uplink communications resources have been disabled by the infrastructure equipment. This allows the PRACH transmission to be prioritised over the disabling of the uplink communications resources. This means the disabled uplink communications resources are not wasted, thus improving communications efficiency. Furthermore, since the PRACH may be used for maintaining a link between the communications device and the infrastructure equipment, radio link performance can be improved. Additionally, since the communications device autonomously re-enables the uplink communications resources, the communications device does not have to wait for a new RRC configuration for the link direction indicator in order to be able to transmit the PRACH in a UL subband, thus saving time and further improving communications efficiency.

[0111] In our co-pending European patent application

[0012] , the link direction indicator may be overwritten by explicit or implicit indication from the gNB. In other words, the gNB is aware when the link direction indicator is overwritten. However, by allowing the communications device to autonomously re-enable the uplink communications resources, the link direction indicator can be overwritten more quickly. This is particularly important for PRACH transmissions which may be high priority.

[0112] Although the following description describes processes performed by UEs and gNBs, this is for ease of explanation only. It will be appreciated that the following description applies equally to processes performed by communications devices and infrastructure equipment of a wireless communications network more generally. The communications device may be half-duplex communications device which is not capable of transmitting on the uplink and receiving on the downlink at the same time.

[0113] Reference is made below to “collisions” between transmissions. It will be appreciated that transmissions collide when they overlap (partially or fully) in time.

[0114] Figure 15 schematically illustrates an example of re-enabling disabled uplink communications resources in an RO in accordance with example embodiments. In Figure 15, every fourth slot (Slot n+3 and Slot n+8 shown in Figure 15) of a {DXXXU} SBFD slot format is indicated by a link direction indicator as DL. Accordingly, the UL subband of Slot n+3 and Slot n+8 is disabled. In Slot n+3, an RO and a CG-PUSCH are configured in the UL subband whilst a SPS occasion is configured in a DL subband of Slot n+3, thereby causing a DL - UL collision. The UE does not have any PRACH transmission. Therefore, the SPS has priority and the RO is not used. Since the UL subband is disabled, the CG-PUSCH is dropped and so the SPS in Slot n+3 is received by the UE. In Slot «+8, an SBFD RO that is in a disabled UL subband collides with SPS and the UE has a PRACH to transmit in the RO. In accordance with example embodiments, the UE re-enables the disabled uplink communications resources comprised in the RO and uses the RO for PRACH transmission. Therefore, the SPS is dropped. In other words, the PRACH has priority even though the RO used for the PRACH was in a disabled subband. It will be appreciated that example embodiments are applicable to SBFD ROs in disabled UL subband even when there is no DL-RO collision.

[0115] In some embodiments, the PRACH transmission in a disabled UL subband overwrites the link direction indicator only for the OFDM symbols that the RO occupies for that PRACH transmission. In such embodiments, the remaining OFDM symbols are not overwritten and remain disabled. Figure 16 schematically illustrates an example of only re-enabling disabled uplink communications resources in an RO in accordance with example embodiments. In Figure 16, a PRACH is transmitted in a SBFD RO that is contained in a disabled UL subband. The PRACH collides with PDSCH. In a similar manner to that explained with Figure 15, the downlink transmission (i.e. the PDSCH) is dropped and the disabled uplink communications resources comprised in the RO are re-enabled. Therefore, the PRACH is transmitted in the RO. In this example, the UE only re-enables the uplink communications resources in OFDM symbols in which the RO is located (first six OFDM symbols in Figure 16) and the uplink communications resources in the other SBFD OFDM symbols in the disabled uplink subband remain disabled. Therefore, since the PUSCH shown in Figure 16 is located in the uplink communications resources in the OFDM symbols which remain disabled, the PUSCH is dropped.

[0116] In some embodiments, a SBFD RO that is valid RO prior to any link direction indication, is still considered as valid if one or more SBFD OFDM symbols in the UL subband that it resides in are disabled by link direction indicator. This recognizes that the SSB-RO association will map SSB indices only to valid ROs, and hence if the SBFD RO is deemed invalid after link direction indicator disabled its UL subband, then that RO would not have SSB mapped onto it, when it is being used for PRACH transmission.

[0117] Types of PRACH

[0118] In some embodiments, the communications device is permitted to re-enable uplink communications resources which have been disabled by a link direction indicator only for one or more types of PRACH (referred to as “permitted PRACH types”).

[0119] In some embodiments, the communications device is permitted to re-enable uplink communications resources which have been disabled by a link direction indicator for one or more of the permitted PRACH types:

[0120] • A PRACH for a handover of the communications device;

[0121] • A PRACH for beam failure recovery;

[0122] • A PRACH for re-synchronisation of the communications device with the infrastructure equipment of the wireless communications network;

[0123] • A PRACH transmitted in response to a Physical Downlink Control Channel (PDCCH) order received from the infrastructure equipment;

[0124] • A PRACH for re-establishing connection to the infrastructure equipment following uplink being received by the communications device when it was not synchronised with the infrastructure equipment;

[0125] • A PRACH for requesting uplink communications resources for an uplink transmission (such as a PUSCH) where the uplink transmission has a high LI priority;

[0126] • A PRACH used for timing advance;

[0127] • A PRACH for re-establishing connection to the infrastructure equipment following radio link failure.

[0128] The present inventors have recognised that the above-listed PRACH types are time-sensitive PRACH types and therefore the PRACH should be transmitted as soon as possible, or overall communication between the UE and gNB will be adversely affected. For example, if the UE does not promptly proceed with the PRACH transmission for beam failure recovery then the UE will lose the connection or become out-of-synch with the gNB. In this situation, the UE needs to reinitiate the connection which require more signaling leading to additional overhead and longer processing time.

[0129] In some embodiments, the communications device is permitted to re-enable uplink communications resources for all of the above-listed types of PRACH. In other embodiments, the communications device is permitted to re-enable uplink communications resources for only one of the above-listed types of PRACH. In other embodiments, the communications device is permitted to re-enable uplink communications resources for a subset of the above-listed types of PRACH.

[0130] In some embodiments, the communications device is permitted to re-enable uplink communications resources which have been disabled by a link direction indicator for a permitted PRACH type only if the PRACH is a retransmission.

[0131] In some embodiments, the communications device may be prohibited from re-enabling uplink communications resources which have been disabled by a link direction indicator for one or more specific types of PRACH.

[0132] In some embodiments, the communications device is not permitted to re-enable uplink communications resources which have been disabled by a link direction indicator for one or more of the following types of PRACH (referred to as “non-permitted PRACH types”):

[0133] • A PRACH for requesting uplink communications resources for an uplink transmission (such as a PUSCH) where the uplink transmission has a low LI priority;

[0134] • A PRACH for re-establishing connection to the infrastructure equipment of the wireless communications network following Scheduling Request (SR) failure;

[0135] • A PRACH for establishing time alignment during Scell addition;

[0136] • A PRACH for requesting on-demand system information.

[0137] In some embodiments, the communications device is permitted to re-enable uplink communications resources which have been disabled by a link direction indicator for one or more of the non-permitted PRACH types if the PRACH is a retransmission. In other words, the communications device may not reenable uplink communications resources which have been disabled by a link direction indicator for a first PRACH transmission if it is one or more of the non-permitted types of PRACH but the communications device may re-enable uplink communications resources which have been disabled by a link direction indicator for a retransmission of PRACH. Currently, uplink transmissions may have one of two LI priorities, namely, a “high LI priority” or “low LI priority” as will be understood by a person skilled in the art. Accordingly, the terms “high LI priority” and “low LI priority” will be understood by a person skilled in the art

[0138] Collisions with other UL Transmissions

[0139] In some embodiments, if an SBLD RO collides with another UL transmission (such as a PUSCH or PUCCH), and both transmissions are partially or fully contained in SBLD OLDM symbols of a UL subband that is disabled by the link direction indicator, then if the PRACH is transmitted in the SBLD RO if it has a higher priority than the other UL transmission. If the other UL transmission has a higher priority than the PRACH, then the UL subband may remain disabled and the other UL transmission is dropped. Alternatively, if the UL transmission has a higher priority than the PRACH, the communications device may determine whether or not to re-enable disabled uplink communications resources comprised in the other UL transmission so that the other UL transmission may be transmitted. The determination of whether or not whether or not to re-enable disabled uplink communications resources comprised in the other UL transmission may use any of the methods discussed in

[0012] , the contents of which are hereby incorporated by reference in their entirety. For example, the communications device may receive an overwrite indicator from the gNB explicitly or implicitly instructing the UE to re-enable the uplink communications resources comprised in the other UL transmission.

[0140] Figure 17 schematically illustrates an example of a PRACH, PUSCH and PDSCH collision in an SBFD slot with UL subband disabled in accordance with example embodiments. Figure 17 illustrates an example where an SBFD RO collides with another UL transmission (e.g. a PUSCH as shown in Figure 17), and both transmissions partially or fully resides in SBFD OFDM symbols of a UL subband that is disabled by the link direction indicator, and these UL transmissions further collide with a DL transmission (e.g. a PDSCH as shown in Figure 17). In some embodiments, the UE may firstly determine whether the PRACH or UL transmission has priority. In some embodiments, a PRACH always has priority over another UL transmission. In some embodiments, the determination of whether the PRACH or UL transmission has priority comprises determining if the PRACH is one of the permitted PRACH types. If the PRACH is one of the permitted PRACH types, then the PRACH has higher priority. In some embodiments, the determination of whether the PRACH or other UL transmission has priority is based on one or more other criteria. For example, the PUSCH may have higher priority if it contains information that is more time sensitive than that contained in the PRACH, or the PUSCH was dynamically scheduled, for example. If the PRACH has priority over the PUSCH, it may be further determined whether the PRACH is one of the permitted PRACH types. If so, the PRACH is transmitted whilst the DL transmission is dropped and the other UL transmission are dropped. On the other hand, if the UL transmission has priority over the PRACH, then in any of the methods discussed in

[0012] can be applied to determine whether or not to re-enable disabled uplink communications resources comprised in the UL transmission. Alternatively, if the UL transmission has priority over the PRACH, then the communications device may determine that the DL transmission has priority over the UL transmission, and the UE follows the instruction of the link direction indicator. In this case, the communications device drops the PRACH transmission and the other UL transmission, and receives the DL transmission.

[0141] In some cases, if the link direction indicator indicates UL (i.e., DL subbands are disabled), and an SBFD RO collides with another UL transmission such as a PUSCH or PUCCH, and both transmissions partially or fully contained in SBFD OFDM symbols of a UL subband, then the UE may firstly determine whether the PRACH or PUSCH / PUCCH has priority. If the PRACH has priority, the UE transmits PRACH and drop any other uplink transmission in that UL subband.

[0142] Although, in the examples discussed above, the PRACH has priority over a DL transmission with which it collides, in other examples the DL transmission may have priority over the PRACH. For example, if the PRACH is one of the non-permitted types of PRACH and / or if the DL transmission is dynamically configured, the DL transmission may have priority over the PRACH. In such examples, the communications device may receive the DL transmission instead of transmitting the PRACH. In some embodiments, a PRACH always has priority over a DL transmission.

[0143] Although, in the examples discussed above, reference has been made to transmissions / receptions being dropped, in other examples such transmissions / receptions may be postponed.

[0144] Those skilled in the art would further appreciate that methods, infrastructure equipment and / or communications devices as herein defined may be further defined in accordance with the various arrangements and embodiments discussed in the preceding paragraphs. It would be further appreciated by those skilled in the art that such infrastructure equipment and communications devices as herein defined and described may form part of communications systems other than those defined by the present disclosure, provided that these are within the scope of the claims. The methods described herein may also be embodied or encoded in a computer-readable medium, such as a computer-readable storage medium, containing instructions. Instructions embedded or encoded in a computer-readable medium may cause a programmable processor, or other processor, to perform the method, e.g., when the instructions are executed. Computer-readable media may include non-transitory computer-readable storage media and transient communication media. Computer readable storage media, which is tangible and non-transitory, may include random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, a hard disk, a CD- ROM, a floppy disk, a cassette, magnetic media, optical media, or other computer-readable storage media. The term “computer-readable storage media” refers to physical storage media, and not signals, carrier waves, or other transient media. As noted above, computer readable media may include transient communication media. Such communication media may occur within a single computer system or between multiple computer systems, and may take the form of transient signal-conveying media such as carrier waves and transmission signals.

[0145] Particular examples of the present disclosure are set forth in the following numbered paragraphs:

[0146] Paragraph 1. A method of operating a communications device to communicate with infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at least one of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed (OFDM) symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the method comprises receiving, from the infrastructure equipment, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmitting on the uplink, determining that the communications device is to transmit a physical random access channel (PRACH) in a PRACH Occasion (RO) comprising at least some of the disabled uplink communications resources, and in response, re-enabling at least the disabled uplink communications resources comprised in the RO for transmitting on the uplink, and transmitting the PRACH in the RO.

[0147] Paragraph 2. A method according to paragraph 1, wherein the re-enabling at least the disabled uplink communications resources comprised in the RO for uplink transmission comprises re-enabling only the disabled uplink communications resources comprised in the one or more of the OFDM symbols in which the RO is located.

[0148] Paragraph 3. A method according to any preceding paragraph, wherein the determining that the communications device is to transmit a PRACH in an RO comprising at least some of the disabled uplink communications resources comprises determining that the RO overlaps in time with a downlink transmission comprising downlink resources from one of the downlink subbands, determining that the PRACH has a higher priority than the downlink transmission, and the method comprises dropping or postponing the downlink transmission. Paragraph 4. A method according to any preceding paragraph, wherein the determining that the communications device is to transmit a PRACH in an RO comprising at least some of the disabled uplink communications resources comprises determining that the RO overlaps in time with another uplink transmission comprising at least some of the disabled uplink communications resources in the at least one uplink subband, determining that the PRACH has a higher priority than the other uplink transmission, and the method comprises dropping or postponing the other uplink transmission.

[0149] Paragraph 5. A method according to any preceding paragraph, wherein the determining that the communications device is to transmit a PRACH in an RO comprising at least some of the disabled uplink communications resources comprises determining that a type of the PRACH to be transmitted in the RO is a type of PRACH for which the communications device is permitted to re-enable the disabled uplink communications resources.

[0150] Paragraph 6. A method according to paragraph 5, wherein the type of the PRACH for which the communications device is permitted to re-enable the disabled uplink communications resources is a PRACH type selected from the list consisting of: a PRACH for a handover of the communications device, a PRACH for beam failure recovery, a PRACH for re-synchronisation of the communications device with the infrastructure equipment, a PRACH transmitted in response to a Physical Downlink Control Channel (PDCCH) order received from the infrastructure equipment, a PRACH for re-establishing connection to the infrastructure equipment following radio link failure, a PRACH used for timing advance, a PRACH for requesting uplink communications resources for an uplink transmission where the uplink transmission has a high LI priority, a PRACH for re-establishing connection to the infrastructure equipment following uplink being received by the communications device when it was not synchronised with the infrastructure equipment.

[0151] Paragraph 7. A method according to paragraph 5 or paragraph 6, wherein the determining that a type of the PRACH to be transmitted in the RO is a type of PRACH for which the communications device is permitted to re-enable the disabled uplink communications resources comprises determining that the type of the PRACH to be transmitted in the RO is a type of PRACH which is only permitted to re-enable the disabled uplink communications resources for re-transmissions.

[0152] Paragraph 8. A method according to paragraph 7, wherein the type of PRACH which is only permitted to re-enable the disabled uplink communications resources for re-transmissions is a PRACH type selected from the list consisting of: a PRACH for requesting uplink communications resources for an uplink transmission where the uplink transmission has a low LI priority, a PRACH for re-establishing connection the infrastructure equipment of the wireless communications network following Scheduling Request (SR) failure, a PRACH for establishing time alignment during Secondary Cell (Scell) addition, and a PRACH for requesting on-demand system information.

[0153] Paragraph 9. A method according to any preceding paragraph, wherein the method comprises determining that the RO comprising at least some of the disabled uplink resources is valid and can therefore be used for Synchronisation Signal Block (SSB) to RO association.

[0154] Paragraph 10. A method of operating infrastructure equipment of a wireless communications network to communicate with a communications device via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at least one of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed, OFDM, symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the method comprises transmitting, to the communications device, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmitting on the uplink, and receiving a physical random access channel (PRACH) in an RO comprising at least some of the disabled uplink communications resources, the disabled resources comprised in the RO having been reenabled for transmitting on the uplink.

[0155] Paragraph 11. A communications device configured to communicate with infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at least one of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed (OFDM) symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the communications device comprises a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive, from the infrastructure equipment, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmitting on the uplink, determine that the communications device is to transmit a physical random access channel (PRACH) in a PRACH Occasion (RO) comprising at least some of the disabled uplink communications resources, and in response, re-enable at least the disabled uplink communications resources comprised in the RO for transmitting on the uplink, and transmit the PRACH in the RO.

[0156] Paragraph 12. Infrastructure equipment for a wireless communications network configured to communicate with a communications device via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at least one of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed, OFDM, symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the infrastructure equipment comprises a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit, to the communications device, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmitting on the uplink, and receive a physical random access channel (PRACH) in an RO comprising at least some of the disabled uplink communications resources, the disabled resources comprised in the RO having been reenabled for transmitting on the uplink.

[0157] Paragraph 13. Circuity for a communications device configured to communicate with infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at least one of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed (OFDM) symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the circuitry comprises transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to receive, from the infrastructure equipment, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmitting on the uplink, determine that the communications device is to transmit a physical random access channel (PRACH) in a PRACH Occasion (RO) comprising at least some of the disabled uplink communications resources, and in response, re-enable at least the disabled uplink communications resources comprised in the RO for transmitting on the uplink, and transmit the PRACH in the RO.

[0158] Paragraph 14. Circuitry for infrastructure equipment of a wireless communications network configured to communicate with a communications device via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at least one of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed, OFDM, symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the circuitry comprises transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to transmit, to the communications device, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmitting on the uplink, and receive a physical random access channel (PRACH) in an RO comprising at least some of the disabled uplink communications resources, the disabled resources comprised in the RO having been reenabled for transmitting on the uplink.

[0159] Paragraph 15. A computer program which, when the program is executed by a computer, cause the computer to perform the method of any of paragraphs 1 to 10.

[0160] Paragraph 16. A non-transitory computer-readable storage medium storing a computer program according to paragraph 15.

[0161] It will be appreciated that the above description for clarity has described embodiments with reference to different functional units, circuitry and / or processors. However, it will be apparent that any suitable distribution of functionality between different functional units, circuitry and / or processors may be used without detracting from the embodiments.

[0162] Described embodiments may be implemented in any suitable form including hardware, software, firmware or any combination of these. Described embodiments may optionally be implemented at least partly as computer software running on one or more data processors and / or digital signal processors. The elements and components of any embodiment may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the disclosed embodiments may be implemented in a single unit or may be physically and functionally distributed between different units, circuitry and / or processors.

[0163] Although the present disclosure has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in any manner suitable to implement the technique.

[0164] References

[0165] [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[0166] [2] TR 38.913, “3rdGeneration Partnership Project; Technical Specification Group Radio Access Network; Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14)”, 3GPP, V14.3.0, August 2017.

[0167] [3] RP -213591, “New SI: Study on evolution of NR duplex operation,” CMCC, RAN#94e, December

[0168] 2021.

[0169] [4] RP -220633, “Revised SID: Study on evolution of NR duplex operation,” CMCC, RAN#95e, March

[0170] 2022.

[0171] [5] RP-234035, “New WID: Evolution of NR duplex operation: Sub-band full duplex (SBFD),” CMCC, RAN# 102, December 2023.

[0172] [6] European Patent No. 3545716.

[0173] [7] TS 38.211 “Physical channels and modulation (Rel-18),” 3GPP, vl8.3.0, June 2024.

[0174] [8] TS 38.213, “Physical layer procedures for control (Rel-18),” 3GPP, vl8.2.0, June 2024.

[0175] [9] Rl-2405425, “Summary #4 of SBFD TX / RX / measurement procedures,” Moderator (CATT), RAN1#117, May 2024.

[0010] Rl-2406134, “SBFD TX / RX / measurement procedures,” Ericsson, RAN1#118, August 2024.

[0176]

[0011] Rl-2406691, “Discussion on subband non-overlapping full duplex Tx-Rx and measurement operations,” NEC, RAN1#118, August 2024.

[0177]

[0012] European Patent Application Number 24189600.0, fded on 18 July 2024.

Claims

CLAIMS1. A method of operating a communications device to communicate with infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at least one of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed (OFDM) symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the method comprises receiving, from the infrastructure equipment, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmitting on the uplink, determining that the communications device is to transmit a physical random access channel (PRACH) in a PRACH Occasion (RO) comprising at least some of the disabled uplink communications resources, and in response, re-enabling at least the disabled uplink communications resources comprised in the RO for transmitting on the uplink, and transmitting the PRACH in the RO.

2. A method according to claim 1, wherein the re-enabling at least the disabled uplink communications resources comprised in the RO for uplink transmission comprises re-enabling only the disabled uplink communications resources comprised in the one or more of the OFDM symbols in which the RO is located.

3. A method according to claim 1, wherein the determining that the communications device is to transmit a PRACH in an RO comprising at least some of the disabled uplink communications resources comprises determining that the RO overlaps in time with a downlink transmission comprising downlink resources from one of the downlink subbands, determining that the PRACH has a higher priority than the downlink transmission, and the method comprises dropping or postponing the downlink transmission.

4. A method according to claim 1, wherein the determining that the communications device is to transmit a PRACH in an RO comprising at least some of the disabled uplink communications resources comprises determining that the RO overlaps in time with another uplink transmission comprising at least some of the disabled uplink communications resources in the at least one uplink subband, determining that the PRACH has a higher priority than the other uplink transmission, and the method comprises23dropping or postponing the other uplink transmission.

5. A method according to claim 1, wherein the determining that the communications device is to transmit a PRACH in an RO comprising at least some of the disabled uplink communications resources comprises determining that a type of the PRACH to be transmitted in the RO is a type of PRACH for which the communications device is permitted to re-enable the disabled uplink communications resources.

6. A method according to claim 5, wherein the type of the PRACH for which the communications device is permitted to re-enable the disabled uplink communications resources is a PRACH type selected from the list consisting of: a PRACH for a handover of the communications device, a PRACH for beam failure recovery, a PRACH for re-synchronisation of the communications device with the infrastructure equipment, a PRACH transmitted in response to a Physical Downlink Control Channel (PDCCH) order received from the infrastructure equipment, a PRACH for re-establishing connection to the infrastructure equipment following radio link failure, a PRACH used for timing advance, a PRACH for requesting uplink communications resources for an uplink transmission where the uplink transmission has a high LI priority, a PRACH for re-establishing connection to the infrastructure equipment following uplink being received by the communications device when it was not synchronised with the infrastructure equipment.

7. A method according to claim 5 , wherein the determining that a type of the PRACH to be transmitted in the RO is a type of PRACH for which the communications device is permitted to re-enable the disabled uplink communications resources comprises determining that the type of the PRACH to be transmitted in the RO is a type of PRACH which is only permitted to re-enable the disabled uplink communications resources for re-transmissions.

8. A method according to claim 7, wherein the type of PRACH which is only permitted to re-enable the disabled uplink communications resources for re-transmissions is a PRACH type selected from the list consisting of: a PRACH for requesting uplink communications resources for an uplink transmission where the uplink transmission has a low LI priority, a PRACH for re-establishing connection the infrastructure equipment of the wireless communications network following Scheduling Request (SR) failure, a PRACH for establishing time alignment during Secondary Cell (Scell) addition, and a PRACH for requesting on- demand system information.

9. A method according to claim 1, wherein the method comprises determining that the RO comprising at least some of the disabled uplink resources is valid and can therefore be used for Synchronisation Signal Block (SSB) to RO association.

10. A method of operating infrastructure equipment of a wireless communications network to communicate with a communications device via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at leastone of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed, OFDM, symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the method comprises transmitting, to the communications device, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmitting on the uplink, and receiving a physical random access channel (PRACH) in an RO comprising at least some of the disabled uplink communications resources, the disabled resources comprised in the RO having been reenabled for transmitting on the uplink.

11. A communications device configured to communicate with infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at least one of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed (OFDM) symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the communications device comprises a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive, from the infrastructure equipment, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmitting on the uplink, determine that the communications device is to transmit a physical random access channel (PRACH) in a PRACH Occasion (RO) comprising at least some of the disabled uplink communications resources, and in response, re-enable at least the disabled uplink communications resources comprised in the RO for transmitting on the uplink, and transmit the PRACH in the RO.

12. Infrastructure equipment for a wireless communications network configured to communicate with a communications device via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at least one of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed, OFDM, symbols are configured with one or more uplink subbands comprising uplink communications resources for transmitting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the infrastructure equipment comprisesa transmiter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmiter and the receiver to transmit, to the communications device, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmiting on the uplink, and receive a physical random access channel (PRACH) in an RO comprising at least some of the disabled uplink communications resources, the disabled resources comprised in the RO having been reenabled for transmiting on the uplink.

13. Circuity for a communications device configured to communicate with infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at least one of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed (OFDM) symbols are configured with one or more uplink subbands comprising uplink communications resources for transmiting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the circuitry comprises transmiter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmiter circuitry and the receiver circuitry to receive, from the infrastructure equipment, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmiting on the uplink, determine that the communications device is to transmit a physical random access channel (PRACH) in a PRACH Occasion (RO) comprising at least some of the disabled uplink communications resources, and in response, re-enable at least the disabled uplink communications resources comprised in the RO for transmiting on the uplink, and transmit the PRACH in the RO.

14. Circuitry for infrastructure equipment of a wireless communications network configured to communicate with a communications device via a radio access interface between the communications device and the infrastructure equipment, the radio access interface comprising one or more slots, at least one of the slots being a sub-band full duplex (SBFD) slot in which one or more Orthogonal Frequency Division Multiplexed, OFDM, symbols are configured with one or more uplink subbands comprising uplink communications resources for transmiting on the uplink and one or more downlink subbands comprising downlink communications resources for receiving on the downlink, and the circuitry comprises26transmiter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmiter circuitry and the receiver circuitry to transmit, to the communications device, a link direction indicator directing the communications device to disable uplink communications resources in at least one of the uplink subbands for transmiting on the uplink, and receive a physical random access channel (PRACH) in an RO comprising at least some of the disabled uplink communications resources, the disabled resources comprised in the RO having been re- enabled for transmiting on the uplink.

15. A computer program which, when the program is executed by a computer, cause the computer to perform the method of claim 1 or claim 10.

16. A non-transitory computer-readable storage medium storing a computer program according to claim 15.

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