WO2025233424A1 - Methods, communications devices, and infrastructure equipment - Google Patents

Abstract

A method of operating a communications device configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment is provided. Here, the communications device is a sub-band full duplex, SBFD, capable communications device. The method comprises determining that the communications device is to perform a random access procedure with the infrastructure equipment, transmitting, to the infrastructure equipment in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of the initial access procedure, and determining, based on at least one characteristic of the first RO, one or more other ROs in which the communications device is to transmit repetition of the PRACH preamble to the infrastructure equipment. Here, one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non-SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface.

Description

METHODS, COMMUNICATIONS DEVICES, AND INFRASTRUCTURE EQUIPMENT

BACKGROUND

Field of Disclosure

The present disclosure relates to communications devices, infrastructure equipment, and methods for the more efficient and effective transmission of data in a wireless communications network.

The present application claims the Paris Convention priority from European patent application number EP24175282.3, filed on 10 May 2024, the contents of which are hereby incorporated by reference.

Description of Related Art

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

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

Current and future wireless communications networks are expected to routinely and efficiently support communications with an ever-increasing range of devices associated with a wider range of data traffic profiles and types than existing systems are optimised to support. For example, it is expected future wireless communications networks will be expected to efficiently support communications with devices including reduced complexity devices, machine type communication (MTC) devices, high 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).

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

SUMMARY OF THE DISCLOSURE

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

At least some embodiments of the present technique can provide a method of operating a communications device configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment. Here, the communications device is a sub-band full duplex, SBFD, capable communications device. The method comprises determining that the communications device is to perform a Random Access procedure with the infrastructure equipment, transmitting, to the infrastructure equipment in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of the random access procedure, and determining, based on at least one characteristic of the first RO, one or more other ROs in which the communications device is to transmit the PRACH preamble multiple times (i.e. transmit repetitions of the initially transmitted preamble) to the infrastructure equipment. Here, one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non-SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface.

At least some further embodiments of the present technique can provide a method of operating a communications device configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment. Here, the communications device is a sub-band full duplex, SBFD, capable communications device. The method comprises receiving, from the infrastructure equipment, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, and determining, based on an indication contained within the PDCCH order, a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment, wherein the indication contained within the PDCCH order indicates either: that the plurality of ROs are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

Such embodiments of the present technique, which, in addition to methods of operating communications devices, relate to methods of operating infrastructure equipment, to communications devices and infrastructure equipment, to circuitry for communications devices and infrastructure equipment, to wireless communications systems, to computer programs, and to computer-readable storage mediums, can allow for the more efficient and effective transmission of uplink signals by a communications device.

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

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

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

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

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;

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;

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

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

Figure 6 schematically illustrates the components of a synchronisation signal block (SSB);

Figure 7 schematically illustrates an SSB burst set transmitted on SSB beams;

Figure 8 schematically illustrates a physical random access channel (PRACH) occasion (RO) configuration;

Figures 9A to 9D schematically illustrates valid and invalid ROs;

Figure 10 schematically illustrates an example of a time division duplexing (TDD) slot format configuration;

Figure 11 schematically illustrates an example of an SSB to RO mapping in an association period for a TDD slot format;

Figure 12 schematically illustrates an example of a set of NPRACH = 4 ROs for 4 x PRACH repetitions;

Figure 13 schematically illustrates an example of an overall SSB-RO association using a single PRACH configuration;

Figure 14 schematically illustrates an example of an SBFD RO configuration on a separate PRACH configuration;

Figure 15 schematically illustrates an example of PRACH repetitions using SBFD ROs and non-SBFD ROs

Figure 16 shows a part schematic, part message flow diagram representation of a first example wireless communications system comprising a communications device and an infrastructure equipment in accordance with embodiments of the present technique;

Figure 17 shows how different antenna panels may be used for SBFD and non-SBFD uplink reception at a gNB in accordance with embodiments of the present technique;

Figure 18 shows an example of preamble partitioning in accordance with embodiments of the present technique;

Figure 19 shows a flow diagram illustrating a first example process of communications in a communications system in accordance with embodiments of the present technique;

Figure 20 shows a part schematic, part message flow diagram representation of a second example wireless communications system comprising a communications device and an infrastructure equipment in accordance with embodiments of the present technique; and

Figure 21 shows a flow diagram illustrating a second example process of communications in a communications system in accordance with embodiments of the present technique. DESCRIPTION OF THE EMBODIMENTS

Long Term Evolution Advanced Radio Access Technology (4G)

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.

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.

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.

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.

New Radio Access Technology (5G)

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],

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.

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.

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.

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.

In terms of broad top-level functionality, the core network 20 connected to the new RAT telecommunications system represented in Figure 2 may be broadly considered to correspond with the core network 2 represented in Figure 1, and the respective central units 40 and their associated distributed units / TRPs 10 may be broadly considered to provide functionality corresponding to the base stations 1 of Figure 1. The term network infrastructure equipment / access node may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems.

Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may lie with the controlling node / central unit and / or the distributed units / TRPs. A communications device 14 is represented in Figure 2 within the coverage area of the first 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.

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.

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.

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.

The transmitters 30, 49 and the receivers 32, 48 (as well as other transmitters, receivers and transceivers descnbed 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) I circuitry / chip(s) / chipset(s). As will be appreciated the infrastructure equipment / TRP / base station as well as the UE / communications device will in general comprise various other elements associated with its operating functionality.

As shown in Figure 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.

The interface 46 between the DU 42 and the CU 40 is known as the F 1 interface which can be a physical or a logical interface. The Fl interface 46 between CU and DU may operate in accordance with specifications 3GPP TS 38.470 and 3GPP TS 38.473, and may be formed from a fibre optic or other wired or wireless high bandwidth connection. In one example the connection 16 from the TRP 10 to the DU 42 is via fibre optic. The connection between a TRP 10 and the core network 20 can be generally referred to as a backhaul, which comprises the interface 16 from the network interface 50 of the TRP 10 to the DU 42 and the Fl interface 46 from the DU 42 to the CU 40.

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). 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 inter-subcarrier interference is avoided or mitigated.

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.

Full Duplex Time Division Duplex (FD-TDD)

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],

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.

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, under-utilised. 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.

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.

Sub-band Full Duplex (SBFD)

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.

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): Subband#! 61, Sub-band#2 62, Sub-band#3 63. The example of Figure 4 is referred to as {DUD}, because two sub-bands, Sub-band# 1 61 and Sub-band#3 63, are used for DL transmissions whilst one sub-band, Sub-band#2 62, is used for UL transmissions. To reduce leakage from one sub-band 61 to 63 to another, a guard sub-band 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.

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#l 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 right-side of Figure 5, a DL sub-band# 1 81 is separated from an UL sub-band#2 83 by a guard subband 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.

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. For example, the system bandwidth may be divided into four sub-bands, which may, using the example of Figure 4, include the two downlink sub-bands 61, 63, the uplink sub-band 62 and another uplink sub-band, though other sub-band arrangements are envisioned. Guard sub-bands may be used in substantially any sub-band arrangement.

Synchronisation Signal Block

As will be known to one skilled in the art, the Synchronisation Signal Block (SSB) is used for initial access and cell reselection. An example of an SSB is schematically illustrated in Figure 6.

As shown in Figure 6, the SSB comprises of a Primary Synchronisation Signal (PSS), a Secondary Synchronisation Signal (SSS) and a Physical Broadcast Channel (PBCH). The SSB comprises information for a communications device, such as a UE, to detect, measure and access a cell. The SSB shown in Figure 6 comprises four OFDM symbols and 240 subcarriers. The PSS and SSS each occupy 127 subcarriers. The PBCH occupies two OFDM symbols of 240 subcarriers and also two blocks of 48 subcarriers at the top and bottom of the SSS. The SSB may be configured with a periodicity, PSSB. of between 5 ms and 160 ms.

An SSB burst set comprises a set of one or more time-multiplexed SSBs. Each SSB is transmitted in a burst set using a different downlink beam, thereby enabling beam sweeping to be implemented for SSB. An SSB burst set may be confined within 5 ms and may comprise up to 4, 8 and 64 SSBs for frequency bands below 3 GHz, between 3 GHz - 6 GHz and for FR2 respectively. As will be understood by one skilled in the art, SSB burst sets may be periodically transmitted.

An example SSB burst set in the case of 3 GHz - 6 GHz frequency is shown in Figure 7. The SSB burst set shown in Figure 7 comprises eight SSBs labelled as SSB#1, SSB#2, SSB#3, SSB#4, SSB#5, SSB#6, SSB#7 and SSB#8 respectively. Each of the SSBs in the burst set is transmitted using a different downlink beam. In this example, two SSBs are configured per slot within four slots. Furthermore, the burst set is transmitted with a periodicity, PSSB, of 20 ms. Although not shown in Figure 7, the SSB burst set is transmitted by infrastructure equipment of a wireless communications network (such as a gNB) and received by a communications device (such as a UE).

The UE measures a signal quality of each SSB in the SSB burst set. The UE may then select one of the downlink beams based on the measured signal quality. For example, the UE may select the downlink beam with the highest measured signal quality provided that the measure signal quality is above a threshold (such as RSRP threshold). Then, the UE determines an uplink beam corresponding to the downlink beam to use for synchronisation with the infrastructure equipment. As will be appreciated by one skilled in the art, corresponding uplink and downlink beams form beam pairs which overlap. Therefore, the measurements of the signal quality of a downlink beam are an indication of the signal quality of the corresponding uplink beam in the beam pair. In initial access, the UE transmits RACH on the determined uplink beam. In one example, the measured signal quality of an SSB is an RSRP of the SSB. The UE may measure the RSRP of each SSB in the SSB burst set and select the downlink beam on which the SSB with the highest RSRP was transmitted provided this measured RSRP is above a threshold (such as rsrp-ThresholdSSB). Then, the UE transmits its RACH using the corresponding uplink beam.

The measurement of the RSRP of an SSB may be referred to as “SS-RSRP”. The measurement of the RSRP of an SSB may comprise measuring the RSRP on resource elements where SSS is transmitted. Alternatively, or in addition, the measurement of the RSRP of an SSB may comprise measuring the RSRP on resource elements where PBCH DMRS is transmitted.

In other examples, the measured signal quality of an SSB may be a Reference Signal Received Quality (SS-RSRQ) of the SSB. The SS-RSRQ is defined as the ratio of N x SS-RSRP / RSSI (Received Signal Strength Indicator), where N is the number of resource blocks. For example, the RSSI in NR is measured in one or more OFDM symbols in a SS/PBCH Block Measurement Time Configuration (SMTC). The SMTC is a configuration to the UE to set time window for measurement by using SSB. The OFDM symbols used for RSSI measurement can be configured by higher layers.

PRACH Occasions

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.

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, and the starting symbol of the PRACH Occasion in a slot and a duration of the PRACH Occasion.

An example PRACH Occasion configuration for an FR1 FDD system is shown Figure 8. The PRACH Occasion is configured with FDM = 2 and with a PRACH Configuration Index = 184. The time resources of the ROs in the PRACH Occasion can be obtained from Table 6.3.3.2-2 of [7]: The PRACH Configuration Period = 20 ms since an RO occurs in every even numbered system frame number (SFN) (x=2 and y=0). In each even numbered SFN, subframe 4 and 9 contain a slot with ROs, i.e., PRACH slot. In this example a 15 kHz subcarrier spacing is assumed and so each subframe which is 1 ms contains 1 slot. In each PRACH slot (i.e. in subframe 4 and 9), there are seven sets of time domain ROs where each RO is two OFDM symbols long. Since FDM = 2, each time domain RO has two ROs, and this gives 14 ROs in a PRACH slot as shown in Figure 8. There are therefore 28 ROs in a PRACH Configuration Period of 20 ms (2 PRACH slots in 20ms * 7 time domain ROs * 2 FDM = 28 ROs). SSB to PRACH Occasion Association

A UE may select an SSB received on a DL beam and transmit a PRACH using a corresponding UL beam. The gNB needs to know which SSB the UE has selected so that it can transmit a Random Access Response (RAR) to the UE using the same SSB beam selected by the UE, or a beam derived from the UE selected SSB beam. Since the UE uses an UL beam, the gNB may maximise its reception by tuning its receiver panels towards the direction of the UL beam. Since ROs and SSBs are configured independently, an SSB-RO association is used for the gNB to determine the UE selected SSB, so that the gNB can determine the SSB selected by the UE based on the RO and preamble used for the UE’s PRACH transmission.

In SSB-RO association, each SSB is associated with one or more ROs and preambles. Infrastructure equipment of a wireless communications network (such as a gNB) transmits an indication of a number of SSBs associated with each RO and a number of preambles associated with each SSB. For example, the infrastructure equipment may transmit the following RRC parameter to the UE: ssb-perRACH- OccasionAndCB-PreamblesPerSSB . The values for SSB to RO association may be {1/8, 1/4, 1/2, 1, 2, 4, 8, 16}. In other words, SSB may be associated with 8, 4, 2 or 1 ROs, and an RO may be associated with 2, 4, 8 or 16 SSBs. In each RO, the SSB may be configured to associate with a subset of the 64 preambles or all of the 64 preambles. For the case where an RO is associated with 2, 4, 8 or 16 SSBs, each SSB may only be associated with a subset of the preambles in an RO. For example, if an RO is associated with two SSBs, then each SSB can occupy at most 32 preambles in that RO. For the case where an SSB is associated with one or more ROs, the SSB can occupy all of the 64 preambles although it can be configured to occupy fewer than 64 preambles.

Once the SSB parameters, RO parameters and SSB-RO association parameters are configured, the UE may then perform the following steps in sequential order:

1. Valid ROs determination;

2 Indexing the valid ROs; and

3 Perform SSB-RO mapping.

Valid ROs Determination

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:

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

• In addition to being fully contained in UL OFDM symbols, there also needs to be a gap of N_gap OFDM symbols between the end of an SSB and the start of the valid RO. The value of N_gap depends 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

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

Examples of valid and invalid ROs are shown in Figures 9 A to 9D. The valid RO shown in Figure 9A 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 9B is invalid because it falls within DL OFDM symbols. The RO of Figure 9C is invalid because there is an insufficient gap between the SSB and the RO. The RO of Figure 9D is invalid because the RO precedes the SSB within the PRACH slot. RO Indexing

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

1 First, in increasing order of preamble indexes within a single RO;

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

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

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

SSB-RO Mapping

The SSBs are then mapped to the indexed ROs sequentially by RO index. This mapping is repeated every “SSB-RO Association Period”. The SSB-RO association period is the smallest integer number of PRACH Configuration Periods required for all the SSBs in an SSB burst set to fully map to RO(s) at least once. In an SSB-RO association period, if any remaining ROs cannot fully map all the SSBs of an SSB burst set, they are invalid ROs and are not used for PRACH transmissions. The allowed SSB-RO association periods for each PRACH Configuration Period are listed in Table 8.1-1 of [8], which is reproduced below as Table I.

Table 1: PRACH Configuration Period and SSB-RO association period (reproduced from / ])

An example of an SSB to RO mapping for an SSB-RO association period will now be explained. Figure 10 illustrates a legacy TDD slot format {DDDDU}, consisting of four DL slots followed by an UL slot as shown in Figure 10, and operating in 15 kHz subcarrier spacing. SSB and PRACH are configured as follows:

• SSB burst set has 5 SSBs {SSB#1, SSB#2, SSB#3, SSB#4, SSB#5};

• SSB per RO = 1/2; i.e., each SSB is mapped to two ROs;

• Preambles per SSB = 64, i.e., all preambles in an RO are fully mapped to an SSB;

• FDM RO = 2; and

• PRACH Configuration Index = 129 for FR1 TDD.

Table 11: PRACH Configuration Index 129 (reproduced from [7])

Using the lookup table in Table 6.3.3.2-3 of [7], the time resource configuration for PRACH Configuration Index = 129 has a PRACH Configuration Period = 10 ms. This is shown in Table II above, which reproduces a portion of this lookup table in Table 6.3.3.2-3 of [7], Figure 11 shows an example of SSB to RO mapping in an association period for the legacy TDD slot format, corresponding to PRACH configuration index 129 as shown in Table II above Here, in each PRACH Configuration Period, Subframe 3, 4, 8 and 9 contain PRACH slots, and in each PRACH slot, there are two time domain ROs with duration six OFDM symbols each, which leads to 16 ROs in a PRACH Configuration Period (four PRACH slots x two time domain ROs per PRACH slot x two FDM ROs). Since a valid RO can only reside in UL OFDM symbols, only subframes 4 and 9 have valid ROs, and the ROs in subframes 3 and 8 are invalid ROs. Hence, each PRACH Configuration Period has eight valid ROs.

For a PRACH Configuration Period = 10 ms, referring to Table I as reproduced above (i.e., from Table 8. 1-1 of [8]), the required SSB-RO association Period to fully map all five SSBs with SSB per RACH = 1/2 is 2 x PRACH Configuration period (20 ms), giving 2 * 8 = 16 valid ROs. The 16 valid ROs in the 20 ms SSB-RO association period are indexed firstly by preamble, secondly by frequency, thirdly by time, and lastly by PRACH slot as shown in Figure 11. The SSBs are then mapped to the indexed ROs sequentially; e.g., since SSB per RO = 1/2, SSB#1 is mapped to RO#1 and RO#2, followed by SSB#2 being mapped to RO#3 and RO#4, etc. The five SSBs are fully mapped to the ROs once in the SSB-RO association period, leaving six remaining ROs: RO#11, RO#12, RO#13, RO#14, RO#15 and RO#16 that cannot folly map to another set of five SSBs. Hence these six remaining ROs are Invalid ROs, and are not used for PRACH transmissions.

PRACH Repetitions

The concept of using PRACH repetitions is introduced in Rel-18 to enhance the uplink coverage of PRACH. The PRACH repetition factor is NPRACH = {2, 4, 8}, where the PRACH is transmitted multiple times in different ROs using the same transmission beam and the same preamble. The set of ROs used for a specific PRACH repetition NPRACH consists of valid ROs that are associated with one SSB (i.e., the selected SSB) and uses the same frequency resources.

Figure 12 is an example of a set of N_PRACH ROS for a PRACH repetition of four, i.e. NPRACH = 4, using the PRACH configurations as described in Figure 11. Figure 12 shows four SSB-RO association periods (each lasting 20 ms), spanning eight radio frames from SFN k to SFN k+~I. where in each SSB-RO association period, the five SSBs are mapped to ten ROs. Assuming the UE selected SSB#2, and requires 4 x PRACH repetitions, it has a choice between two sets of N_PRACH=^ ROS, i.e. one that starts with RO#3 (the lower frequency RO) in SFN k and another that starts with RO#4 (the higher frequency RO) in SFN k. Here, the UE selects RO#3 in SFN k as the start of the PRACH repetition. The remaining ROs in the set of NRRACH=^ ROS are associated with the same SSB#2 and located in the same frequency; that is, the set of NPRAC =4 ROs are RO#3 in SFN k, SFN k+2, SFN k+4 and SFN k+6, which are outlined in dashed boxes m the example of Figure 12.

The first set of NPRACH ROs starts from SFN 0 and there may be a gap of TimeOffsetBetweenStartingRO valid ROs between each set of NPRACH ROS. The value of TimeOffsetBetweenStartingRO is configured by the network.

SBFD ROs

In the current system, there are two methods to configure ROs for SBFD (i.e. ROs that can be configured in SBFD sub-bands and hence are usable by SBFD-capable UEs), which are also described in co-pending European patent application number EP24155834.5 [9], the contents of which are hereby incorporated by reference. That is: • Single PRACH Configuration: SBFD ROs and legacy ROs are configured in a single PRACH configuration; and

• Additional PRACH Configurations: SBFD ROs and legacy ROs are configured in separate PRACH configurations, i.e., an additional/separate PRACH configuration is used for SBFD ROs.

For each of these SBFD RO configuration methods, SBFD UEs will need to perform the SSB-RO association twice, where the first of these is performed on valid ROs that are validated using legacy RO validation rules, and the second SSB-RO association for SBFD RO is performed using new RO validation rules. Such new RO validation rules for SBFD RO are introduced, where an RO is valid if it resides fully within an UL sub-band and does not overlap with SSB.

The SSB-RO association for SBFD RO has not yet been specified, but a potential overall SSB-RO association is shown in Figure 13, where the example PRACH configuration as used in the example in Figure 11 is used again here (i.e. corresponding to PRACH configuration index 129 as shown in Table II). Here, an {XXXXU} SBFD slot format is assumed, where “X” is a slot consisting of SBFD OFDM symbols, where in the example in Figure 13, the SBFD slots consists of a {DUD} sub-band arrangement in the frequency domain such as that shown in Figure 4.

In the example of Figure 13, the UE performs an SSB-RO association using legacy RO validation rules for non-SBFD OFDM symbols, where it maps SSB#1 and SSB#2 to RO#1 and RO#2, and RO#3 and RO#4 respectively in Subframe 4 of SFN k, SSB#3 and SSB#4 to RO#5 and RO#6, and RO#7 and RO#8 respectively in Subframe 9 of SFN k, and SSB#5 to RO#9 and RO#10 in Subframe 4 of SFN k+ . The UE performs a second SSB-RO association on SBFD OFDM symbols, where it maps SSB#1 and SSB#2 to RO#1 and RO#2, and RO#3 and RO#4 respectively in Subframe 3 of SFN k, SSB#3 and SSB#4 to RO#5 and RO#6, and RO#7 and RO#8 respectively in Subframe 8 of SFN k, and SSB#5 to RO#9 and RO# 10 in Subframe 3 of SFN k+ 1. The overall SSB-RO association combining the two SSB-RO associations is shown in Figure 13.

Table III below shows the parameters for an example SBFD RO using a separate PRACH configuration, i.e. the SBFD UE is configured with two PRACH configurations.

Here the SBFD UE also performs two SSB-RO association with different RO validations but on different PRACH configurations, where a first SSB-RO association using legacy RO validation rules on the legacy PRACH configuration (PRACH Configuration Index = 127) and another SSB-RO association using the new SBFD RO validation rules on the additional PRACH configuration with PRACH Configuration Index = 125, as shown in Table IV below. The resultant SSB-RO mapping is shown in Figure 14, where the SBFD ROs occupies different frequency resources from the legacy TDD ROs. Table TV: PRACH Configuration Indices 125 and 127 (reproduced from [7])

Technical Issue

PRACH repetition for SBFD is currently being considered in 3GPP. The benefit of introducing SBFD RO is that it increases the number of RO for RACH access and for the case of PRACH repetition, it may enable a PRACH repetition of N_PRACH to complete faster.

Figure 15 shows two association periods of the SSB-RO mapping for PRACH configuration used in the example in Figure 13, where the SBFD RO and legacy TDD RO are configured on a single PRACH configuration. For a legacy TDD UE, it can only use the RO in UL slot, i.e. in Subframe 4 or Subframe 9 in each SFN, and hence for the example shown in Figure 15, a legacy TDD UE can only transmit 2 x PRACH repetitions within the two association periods or 40 ms (from SFN k to SFN k+3). For example, if the legacy UE selects SSB#2, it will start its PRACH repetition using RO#3 in Subframe 4 of SFN k, followed by a second PRACH repetition in RO#3 in Subframe 4 of SFN k+2, thereby achieving 2 x PRACH repetitions within two association periods (40 ms). In contrast, if an SBFD UE selects SSB#4 (or any SSB), it may start its PRACH repetitions in RO#8 in Subframe 8 (an SBFD slot) of SFN k, followed by the second, third and fourth PRACH repetitions in RO#8 in Subframe 9 (Uplink slot) of SFN k, Subframe 8 of SFN k+2, and Subframe 9 of SFN k+2 respectively. That is within the same time period, i.e. of two association periods (or 40 ms in this example), the SBFD UE can achieve 4 x PRACH repetitions compared to just 2 x PRACH repetitions by the legacy TDD UE. Another way to look at this is that an SBFD UE can complete a 2 x PRACH repetitions within one association period rather than two association periods as compared to a legacy UE. For example, a 2 x PRACH repetition of SSB#4 can use RO#8 in Subframe 8 and Subframe 9 of SFN k.

Although using SBFD RO and legacy TDD RO enables transmission of a PRACH with NPRACH repetitions to be completed faster, there may be ambiguity at the gNB in respect of determining whether a PRACH repetition using an RO in an UL slot is part of a set of PRACH repetitions from an SBFD UE or a legacy UE. For example, for a PRACH transmitted in RO#8 in Subframe 9 of SFN k, it may be either the first PRACH repetition for a legacy UE or it may be the second PRACH repetition for an SBFD UE (that started its repetition in RO#8 in Subframe 8 of SFN k).

In [10], it is proposed that a set of NPRACH ROS contains only SBFD ROs or only non-SBFD ROs. That is, a set of NPRACH RO cannot contain a mixture of SBFD ROs and non-SBFD ROs. In this way, there is no ambiguity in respect of whether a non-SBFD RO belongs to a PRACH repetition from an SBFD UE or a legacy UE. However, this defeats the purpose of introducing SBFD ROs in the first place, since restricting a set of NPRACH ROS to only SBFD ROs or only non-SBFD ROs may not reduce the latency in completing the set of NPRAC PRACH repetitions.

For the example in Figure 15, if the SBFD UE selects SSB#4, it can only achieve a 2 * PRACH repetition within the four association periods, i.e. it can either transmit two PRACH repetitions in RO#8 in SBFD slot in Subframe 8 of SFN k and SFN k+2, or in RO#8 in UL slot in Subframe 9 of SFN k and SFN k+2, rather than use all of these ROs. Hence, the technical problem to solve is to enable a set of NPRACH ROS for PRACH repetitions to contain both SBFD ROs and non-SBFD ROs so as to reduce overall latency in transmission of the set of N_PRACH PRACH repetitions, but in such a manner that reduces ambiguity at the gNB. Embodiments of the present technique seek to provide solutions to such a technical problem.

Determining SBFD PRACH Repetitions Based on First RO

Figure 16 shows a part schematic, part message flow diagram representation of a wireless communications system comprising a communications device 101 (e.g. a UE 14) and an infrastructure equipment 102 (e.g. a gNB / TRP 10) in accordance with at least some embodiments of the present technique. Here, the communications device 101 is a sub-band full duplex, SBFD, capable communications device (SBFD UE), meaning that it is able to understand SBFD configurations and transmit signals and receive signals at the same time (i.e. in accordance with a full duplex operation) using configured SBFD UL and DL sub-bands.

The communications device 101 may be configured to transmit signals to and/or receive signals from the wireless communications network, for example, to and from the infrastructure equipment 102. Specifically, the communications device 101 may be configured to transmit data to and/or receive data from the wireless communications network (e.g. to/from the infrastructure equipment 102) via a wireless radio interface provided by the wireless communications network (e.g. a Uu interface between the communications device 101 and the Radio Access Network (RAN), which includes the infrastructure equipment 102). The communications device 101 and the infrastructure equipment 102 each comprise a transceiver (or transceiver circuitry) 101.1, 102.1, and a controller (or controller circuitry) 101.2, 102.2. Each of the controllers 101.2, 102.2 may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc. The controllers 101.2, 102.2 may also each be equipped with a memory unit (which is not shown in Figure 16).

As shown in the example ofFigure 16, the controller 101.2 of the communications device 101 is configured to control the transceiver 101.1 of the communications device 101 to determine 103 that the communications device 101 is to perform a random access procedure with the infrastructure equipment 102 (e.g. for initial access to the infrastructure equipment from idle mode, or to obtain a timing advance, or for beam management, etc.), to transmit 104, to the infrastructure equipment 102 in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of the random access procedure, and to determine 105, based on at least one characteristic of the first RO, one or more other ROs in which the communications device 101 is to transmit repetitions of the PRACH preamble to the infrastructure equipment 102. Here, one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non-SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface.

Essentially then, some embodiments of the present technique, as exemplified by the example wireless communications system ofFigure 16 for example, propose that a combination of SBFD ROs and non- SBFD ROs for carrying subsequent PRACH repetitions may be enabled under certain circumstances, and based on the RO resources used for the first PRACH repetition.

In some arrangements of embodiments of the present technique, the said RO resource of the first PRACH repetition is the type of OFDM symbol used. In other words, the at least one characteristic of the first RO may be a type of symbol(s) within which the first RO is transmited. That is if the first PRACH repetition uses an RO in an SBFD OFDM symbol, i.e., the PRACH repetition starts with an SBFD RO, then the set of NPRACH RO of a NPRACH PRACH repetition can contain SBFD RO and non-SBFD RO. If the first PRACH repetition uses an RO in a non-SBFD OFDM symbol such as in UL OFDM symbols (or in an UL slot), i.e., the PRACH repetition starts with a non-SBFD RO, then the set of NPRACH RO of a NPRACH PRACH repetition contains only non-SBFD ROs. In other words, the communications device may be configured to determine, if the type of symbols within which the first RO is transmitted is an SBFD symbol, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or to determine, if the type of symbols within which the first RO is transmitted is a non-SBFD uplink symbol, that all of the one or more other ROs are non-SBFD ROs.

It should be noted that the gNB may use separate DL and UL antenna panels for DL transmission and UL reception respectively in SBFD OFDM symbols, to reduce self-interference caused by the Cross Link Interference (CLI) from the DL transmission into the UL reception at the gNB, by having physical separation between the DL transmission and UL reception. The gNB may use a TDD antenna panel that is used for both DL transmission and UL reception for non-SBFD OFDM symbols, since in non-SBFD OFDM symbols, DL and UL cannot occur simultaneously and so there is no risk of CLI.

For example, as can be seen in Figure 17, PRACH# 1 is transmitted in non-SBFD OFDM symbols (i.e. in an UL slot) and it is received using the “TDD” antenna panel at the gNB. PRACH#2 is transmitted in the UL sub-band of SBFD OFDM symbols and it is received using the “UL” antenna panel at the gNB, where the “UL” antenna panel is separate from the “DL” antenna panel and the “TDD” panel. If the gNB also transmits a PDSCH in the DL to another UE, it may use the “DL” antenna panel, to provide physical isolation between the DL transmission of PDSCH and UL reception of PRACH#2, to reduce the selfinterference caused by the CLI from the DL transmission by the gNB.

Such arrangements (where the subsequent ROs depend on the symbols that carry the first RO) therefore recognise the use of separate antenna panels and that a gNB likely continue to use the same antenna panel for all PRACH repetitions, to maintain the same radio channel in its reception. Hence, if the first PRACH repetition starts in an SBFD RO, the gNB would receive that PRACH using an UL only antenna panel, e.g. antenna panel “UL” in Figure 17. If one or more subsequent PRACH repetitions are transmitted from non-SBFD ROs, e.g., an RO in an UL slot, the gNB may continue to receive them using the same “UL” antenna panel without causing any self-interference since there are no DL transmissions in UL OFDM symbols. On the other hand, if the first PRACH repetition starts in a non-SBFD RO, e.g., in an UL slot, the gNB may receive that PRACH using the TDD panel and if one or more subsequent PRACH repetitions are transmitted from SBFD RO, the gNB may not be able to continue receiving them using the “TDD” panel since it may cause self-interference due to DL transmission in the DL sub-band. Therefore, as per such arrangements, if the first PRACH repetition starts in a non-SBFD RO, then the subsequent PRACH repetitions are transmitted only in non-SBFD RO.

Since the gNB configures the ROs, it is aware which RO is the start of a PRACH repetition. That is, the gNB is aware the start of each SSB-RO association period and is aware of the SFN and subframe where each RO resides, and therefore the gNB can work out the RO for the first PRACH repetition. For the case where the first PRACH repetition uses an SBFD RO, the gNB may need to perform blind decoding on the RO in non-SBFD OFDM symbols, such as in an UL slot to determine whether the RO belongs to a PRACH repetition for an SBFD PRACH transmission or a legacy PRACH transmission.

In some arrangements of embodiments of the present technique, the said RO resource is to use different preamble for PRACH repetitions that can span across SBFD RO and non-SBFD RO, and PRACH repetitions that can only be in SBFD RO or only in non-SBFD RO. In other words, the at least one characteristic of the first RO may be a preamble set to which the PRACH preamble transmitted in the first RO belongs.

That is preamble partitioning is used to distinguish between PRACH repetitions that can contain SBFD RO and non-SBFD RO, and only SBFD RO or only non-SBFD RO. In other words, the communications device may be configured to determine, if the preamble set is a first preamble set, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, to determine, if the preamble set is a second preamble set, that all of the one or more other ROs are SBFD ROs, or to determine, if the preamble set is a third preamble set, that all of the one or more other ROs are non-SBFD ROs.

In some such arrangements of embodiments of the present technique, if the preamble set is a fourth preamble set (which may be a further separate preamble set to the three sets described in the paragraph above, or may be in place of the second and third preamble sets as described in the paragraph above such that there are only two preamble sets rather than three as described in the paragraph above), all of the one or more other ROs are SBFD ROs if the first RO is an SBFD RO, and all of the one or more other ROs are non-SBFD ROs if the first RO is a non-SBFD RO. In other words, the communications device may be configured to determine, if the preamble set is a first preamble set, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or to determine, if the preamble set is a second preamble set, either that all of the one or more other ROs are SBFD ROs if the first RO is an SBFD RO, or that all of the one or more other ROs are non-SBFD ROs if the first RO is a non-SBFD RO. That is, preambles from a first set indicate that ROs that can be used may be a mixture of SBFD ROs and non-SBFD ROs, while preambles from a second set indicate that ROs may only be used if they are of the same type as the initial RO (i.e. the preamble is initially sent in an SBFD RO, and belongs to the second set, so all repetitions must also be sent in SFBD ROs, and similarly the preamble is initially sent in a non-SBFD RO, and belongs to the second set, all repetitions must also be sent in non-SBFD ROs).

An example of such arrangements is shown in Figure 18, where the 64 preambles are partitioned such that preambles Po to Pt are for PRACH repetitions that can contain only SBFD RO or only non-SBFD RO, whilst Preambles Pk+i to P₆₃ are for PRACH repetitions that can contain both SBFD RO and non-SBFD RO.

In Figure 18, four ROs are shown with two SBFD ROs, i.e., SBFD RO#1 and SBFD RO#2, and two non- SBFD ROs, i.e., Non-SBFD RO#1 and Non-SBFD RO#2. If a UE starts a PRACH repetition using SBFD RO# 1 with a preamble from P_k+1 to P₆₃, then that repetition can include non-SBFD RO, and in this case the UE can achieve 4 x PRACH repetitions, using SBFD RO#1, Non-SBFD RO#1, SBFD RO#2 and Non-SBFD RO#2, which is shown as Set 1 with NPRACH = 4 ROs in Figure 18. If the UE starts its PRACH with SBFD RO#1 with a preamble from Po to Pt, then its PRACH repetition can contain only SBFD ROs, i.e. it can achieve only a 2 * PRACH repetitions with SBFD RO#1 and SBFD RO#2, which is labelled as Set 2 in Figure 18. If the UE starts its PRACH with Non-SBFD RO#1 with a preamble from P_o to Fk, then its PRACH repetition can contain only Non-SBFD ROs, i.e., it can achieve only a 2 x PRACH repetitions with Non-SBFD RO#1 and Non-SBFD RO#2, which is labelled as Set 3 in Figure 18.

It should be noted that, although this is not shown in Figure 18, it is possible using such arrangements to configure a set of N_PRACH = 2 ROs. That is, 2 * PRACH repetitions starting with Non-SBFD RO#1 and SBFD RO#2 using a preamble from Pk+ to Po . It should be noted that the example of Figure 18 is merely one example implementation/configuration and other implementations and configurations with different N_PRACH values, different numbers of sets, and different preambles partitioning can of course be used. Hence, using preamble partitioning, there is therefore no ambiguity at the gNB as to whether a non-SBFD RO is used for SBFD PRACH repetition or for legacy PRACH repetition, because the gNB is able to determine which ROs will be used for future repetitions based on which set the received preamble in the first repetition belongs to.

In some arrangements of embodiments of the present technique, the frequency resource of the RO used for the first PRACH repetition determines whether the set of NPPACH ROs for a NPRACH PRACH repetition can contain SBFD RO and non-SBFD RO, or not. In other words, the at least one characteristic of the first RO is a frequency resource of the first RO.

Such arrangements are applicable for the case where the FDM RO > 2, so that the gNB can configure or dynamically indicate which frequency resources allows a mixture of SBFD ROs and non-SBFD ROs, and which allow only SBFD ROs or only non-SBFD ROs in a set of PRACH repetitions. In other words, the communications device may be configured to determine, if the frequency resource of the first RO is a first frequency resource, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, to determine, if the frequency resource of the first RO is a second frequency resource, that all of the one or more other ROs are SBFD ROs, or to determine, if the frequency resource of the first RO is a third frequency resource, that all of the one or more other ROs are non-SBFD ROs.

In some such arrangements of embodiments of the present technique, there may be two different frequency resources rather than three, where the second frequency resource may be in place of the second and third frequency resources as described in the paragraph above). Here, if the frequency resource of the RO used for the first PRACH repetition indicates that the PRACH repetition can contain only SBFD ROs, or only non-SBFD ROs, the RO of the first PRACH repetition also indicates whether the entire PRACH repetitions are all SBFD ROs or non-SBFD ROs. In other words, the communications device may be configured to determine, if the frequency resource of the first RO is a first frequency resource, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or to determine, if the frequency resource of the first RO is a second frequency resource, either that, that all of the one or more other ROs are SBFD ROs if the first RO is an SBFD RO, or that all of the one or more other ROs are non-SBFD ROs if the first RO is a non-SBFD RO. That is, if the RO for the first PRACH repetition uses SBFD RO, then all the remaining PRACH repetitions use SBFD RO, and if the RO for the first PRACH repetition uses non-SBFD RO, then all the remaining PRACH repetitions use non-SBFD RO.

An example can be understood with respect to Figure 15, where here the ROs in the higher frequency (i.e. the even-numbered ROs) allow PRACH repetitions to contain a mixture of SBFD RO and non-SBFD RO, whilst ROs in the lower frequency (i.e. the odd-numbered ROs) allow PRACH repetitions to contain only SBFD ROs, or only non-SBFD ROs.

Here, if an SBFD UE selects SSB#2 and transmits its first PRACH repetition using RO#3 in Subframe 4 of SFN k, since RO#3 uses a lower frequency and Subframe 4 is a non-SBFD slot, as per such arrangements, PRACH repetition can only contain non-SBFD ROs, and in this example the SBFD UE achieves 2 x PRACH repetitions from SFN k to SNF k+3. Another (SBFD) UE may select SSB#4, and transmits its first PRACH repetition using RO#8 in Subframe 8 of SFN C Here, since RO#8 resides in an upper frequency, as per such arrangements, this SBFD UE can perform 4 x PRACH repetitions within SFN k to SNF k+3. It should be noted that other FDM configurations are possible. For example, the gNB may configure FDM RO = 4, where the (initial) ROs are in frequencies and it may configure this such that f\ and fi allow PRACH repetitions to contain SBFD ROs and non-SBFD ROs, whilst (initial) ROs in ₂ and f, allow PRACH repetitions to contain only SBFD ROs, or only non-SBFD ROs. In some arrangements of embodiments of the present technique, if the RO that carries the initial repetition of the PRACH is an SBFD RO that was configured on a separate (i.e. additional) PRACH configuration to non-SBFD ROs, then the set of NPRACH ROS for NPRACH PRACH repetition can contain both SBFD ROs and non-SBFD ROs. In other words, the first RO may be an SBFD RO and the at least one characteristic of the first RO is a type of configuration (received by the communications device from the infrastructure equipment) of the first RO. Here, the communications device may be configured to determine, if the type of configuration was a separate PRACH configuration for use only by SBFD-capable communications devices, that the one or more other ROs are either SBFD ROs or non-SBFD ROs.

Here, in some implementations, the communications device may also be configured to determine, if the type of configuration was a single PRACH configuration for use by both SBFD-capable communications devices and non-SBFD-capable communications devices, that all of the one or more other ROs are SBFD ROs - but in other implementations it is not necessary for the communications device to make such a determination, as the communications device may be able to make a decision on what ROs to use for the PRACH repetitions based on, for example, the type of the first RO, the preamble set from which the PRACH preamble was taken, or the frequency resource of the first RO, as described in arrangements of embodiments of the present technique above.

As described previously, SBFD ROs can be configured using a single PRACH configuration or an additional (i.e., multiple) PRACH configuration. For the case where an additional PRACH configuration is used, the ROs configured under this additional PRACH configuration are dedicated for SBFD PRACH operation, and so there would not be any ambiguity at the gNB in respect of whether the non-SBFD ROs, i.e., ROs configured for SBFD PRACH operation but residing in non-SBFD OFDM symbols such as in an UL slot, is for legacy UEs or SBFD UEs.

Figure 19 shows a flow diagram illustrating a first example process of communications in a communications system in accordance with embodiments of the present technique. The process shown by Figure 19 is specifically a method of operating a communications device (e g. UE) configured to transmit signals to and/or to receive signals from an infrastructure equipment (e g . a gNB) of a wireless communications network, where here, the communications device is a sub-band full duplex, SBFD, capable communications device.

The method begins in step Si l. The method comprises, in step SI 2, determining that the communications device is to perform a random access procedure with the infrastructure equipment. In step SI 3, the process comprises transmitting, to the infrastructure equipment in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of the random access procedure. The method then comprises, in step S14, determining, based on at least one characteristic of the first RO, one or more other ROs in which the communications device is to transmit repetitions of the PRACH preamble to the infrastructure equipment, where here, one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non-SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface. The process ends in step S15.

Determining SBFD PRACH Repetitions Based on PDCCH Order

Figure 20 shows a part schematic, part message flow diagram representation of a wireless communications system comprising a communications device 201 (e.g. a UE 14) and an infrastructure equipment 202 (e.g. a gNB / TRP 10) in accordance with at least some embodiments of the present technique. Here, the communications device 201 is a sub-band full duplex, SBFD, capable communications device (SBFD UE), meaning that it is able to understand SBFD configurations and transmit signals and receive signals at the same time (i.e. in accordance with a full duplex operation) using configured SBFD UL and DL sub-bands.

The communications device 201 may be configured to transmit signals to and/or receive signals from the wireless communications network, for example, to and from the infrastructure equipment 202. Specifically, the communications device 201 may be configured to transmit data to and/or receive data from the wireless communications network (e.g. to/from the infrastructure equipment 202) via a wireless radio interface provided by the wireless communications network (e.g. a Uu interface between the communications device 201 and the Radio Access Network (RAN), which includes the infrastructure equipment 202). The communications device 201 and the infrastructure equipment 202 each comprise a transceiver (or transceiver circuitry) 201.1, 202.1, and a controller (or controller circuitry) 201.2, 202.2. Each of the controllers 201.2, 202.2 may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc. The controllers 201.2, 202.2 may also each be equipped with a memory unit (which is not shown in Figure 20).

As shown in the example of Figure 20, the controller 201.2 of the communications device 201 is configured to control the transceiver 201.1 of the communications device 201 to receive 203, from the infrastructure equipment 202, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device 201 is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment 202 in accordance with an indicated number of repetitions, and to determine 204, based on an indication contained within the PDCCH order, a plurality of PRACH, occasion, ROs, in which the communications device 201 is to transmit the repetitions of the PRACH preamble to the infrastructure equipment 202. Here, the indication contained within the PDCCH order indicates either: that the plurality of ROs are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only nonSB FD ROs which are contained within non-SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

Essentially then, some embodiments of the present technique, as exemplified by the example wireless communications system of Figure 20 for example, propose that, for PRACH repetition triggered by a PDCCH order in RRC Connected Mode, the PDCCH order indicates whether the PRACH repetition can contain SBFD RO and non-SBFD RO, only SBFD RO, or only non-SBFD RO. Since the gNB indicates whether a PRACH repetition can have a mixture of SBFD RO and non-SBFD RO, or not, there is no ambiguity at the gNB.

It should be noted here that the PDCCH order indicates the preamble and RO Mask Index that the UE is to use for its PRACH transmission, and so it knows which RO (SBFD and non-SBFD) is being used for the PRACH repetition. Furthermore, those skilled in the art would appreciate that such a PDCCH order may only be transmitted while the UE is in RRC connected mode (or the gNB otherwise retains context information associated with the UE), as the gNB is required to know the UE’s SBFD capability in order to provide such an indication of ROs in the PDCCH order.

Figure 21 shows a flow diagram illustrating a second example process of communications in a communications system in accordance with embodiments of the present technique. The process shown by Figure 21 is specifically a method of operating a communications device (e g. UE) configured to transmit signals to and/or to receive signals from an infrastructure equipment (e.g. a gNB) of a wireless communications network, where here, the communications device is a sub-band full duplex, SBFD, capable communications device. The method begins in step S21. The method comprises, in step S22, receiving, from the infrastructure equipment, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions. In step S23, the process comprises determining, based on an indication contained within the PDCCH order, a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment. Here, the indication contained within the PDCCH order indicates either: that the plurality of ROs are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs. The process ends in step S24.

Those skilled in the art would appreciate that the methods shown by Figures 19 and 21 may be adapted in accordance with embodiments of the present technique. For example, other intermediate steps may be included in such methods, or the steps may be performed in any logical order. Though embodiments of the present technique have been described largely by way of the example communications systems shown in Figures 16 and 20, and the implementation examples described with respect to Figures 17 and 18, it would be clear to those skilled in the art that they could be equally applied to other systems to those described herein, provided that these are within the scope of the claims.

For example, it should be appreciated that arrangements of embodiments of the present technique described herein may be implemented individually or in a combined manner. For example, the OFDM symbol type of the RO of the first PRACH repetition can be combined with PRACH preamble partitioning, where a set of preambles may use SBFD ROs and non-SBFD ROs if the first PRACH repetition starts with an SBFD RO, and if it starts with non-SBFD RO, it uses only non-SBFD ROs. Other combinations are of course feasible and would be apparent to those skilled in the art.

Those skilled in the art would further appreciate that such infrastructure equipment and/or communications devices as herein defined may be further defined in accordance with the various arrangements and embodiments discussed in the preceding paragraphs. It would be further appreciated by those skilled in the art that such infrastructure equipment and communications devices as herein defined and described may form part of communications systems other than those defined by the present disclosure, provided that these are within the scope of the claims.

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

Paragraph 1. A method of operating a communications device configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, the method comprising determining that the communications device is to perform a random access procedure with the infrastructure equipment, transmitting, to the infrastructure equipment in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of the random access procedure, and determining, based on at least one characteristic of the first RO, one or more other ROs in which the communications device is to transmit repetitions of the PRACH preamble to the infrastructure equipment, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface.

Paragraph 2. A method according to Paragraph 1, wherein the at least one characteristic of the first RO is a type of symbols within which the first RO is transmitted.

Paragraph 3. A method according to Paragraph 2, comprising determining, if the type of symbols within which the first RO is transmitted is an SBFD symbol, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the type of symbols within which the first RO is transmitted is a non-SBFD uplink symbol, that all of the one or more other ROs are non-SBFD ROs

Paragraph 4. A method according to any of Paragraphs 1 to 3, wherein the at least one characteristic of the first RO is a preamble set to which the PRACH preamble transmitted in the first RO belongs.

Paragraph 5. A method according to Paragraph 4, comprising determining, if the preamble set is a first preamble set, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, determining, if the preamble set is a second preamble set, that all of the one or more other ROs are SBFD ROs, or determining, if the preamble set is a third preamble set, that all of the one or more other ROs are non-SBFD ROs.

Paragraph 6. A method according to Paragraph 4, comprising determining, if the preamble set is a first preamble set, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the preamble set is a second preamble set, either that all of the one or more other ROs are SBFD ROs if the first RO is an SBFD RO, or that all of the one or more other ROs are non-SBFD ROs if the first RO is a non-SBFD

RO.

Paragraph 7. A method according to any of Paragraphs 1 to 6, wherein the at least one characteristic of the first RO is a frequency resource of the first RO.

Paragraph 8. A method according to Paragraph 7, comprising determining, if the frequency resource of the first RO is a first frequency resource, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, determining, if the frequency resource of the first RO is a second frequency resource, that all of the one or more other ROs are SBFD ROs, or determining, if the frequency resource of the first RO is a third frequency resource, that all of the one or more other ROs are non-SBFD ROs.

Paragraph 9. A method according to Paragraph 7, comprising determining, if the frequency resource of the first RO is a first frequency resource, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the frequency resource of the first RO is a second frequency resource, either that, that all of the one or more other ROs are SBFD ROs if the first RO is an SBFD RO, or that all of the one or more other ROs are non-SBFD ROs if the first RO is a non-SBFD RO.

Paragraph 10. A method according to any of Paragraphs 1 to 9, wherein the first RO is an SBFD RO and the at least one characteristic of the first RO is a type of configuration of the first RO.

Paragraph 11. A method according to Paragraph 10, comprising determining, if the type of configuration was a separate PRACH configuration for use only by SBFD-capable communications devices, that the one or more other ROs are either SBFD ROs or non- SBFD ROs.

Paragraph 12. A communications device, the communications device being a sub-band full duplex, SBFD, capable communications device and comprising transceiver circuitry configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, and controller circuitry configured in combination with the transceiver circuitry to determine that the communications device is to perform a random access procedure with the infrastructure equipment, to transmit, to the infrastructure equipment in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of the random access procedure, and to determine, based on at least one characteristic of the first RO, one or more other ROs in which the communications device is to transmit repetitions of the PRACH preamble to the infrastructure equipment, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface. Paragraph 13. Circuitry for a communications device, the communications device being a sub-band full duplex, SBFD, capable communications device, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, and controller circuitry configured in combination with the transceiver circuitry to determine that the communications device is to perform a random access procedure with the infrastructure equipment, to transmit, to the infrastructure equipment in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of the random access procedure, and to determine, based on at least one characteristic of the first RO, one or more other ROs in which the communications device is to transmit repetitions of the PRACH preamble to the infrastructure equipment, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface. Paragraph 14. A method of operating an infrastructure equipment forming part of a wireless communications network and configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, the method comprising receiving, from the communications device in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of a random access procedure performed by the communications device with the infrastructure equipment, and determining, based on at least one characteristic of the first RO, one or more other ROs in which the infrastructure equipment is to receive repetitions of the PRACH preamble from the communications device, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface.

Paragraph 15. A method according to Paragraph 14, wherein the at least one characteristic of the first RO is a type of symbols within which the first RO is transmitted.

Paragraph 16. A method according to Paragraph 15, comprising determining, if the type of symbols within which the first RO is transmitted is an SBFD symbol, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the type of symbols within which the first RO is transmitted is a non-SBFD uplink symbol, that all of the one or more other ROs are non-SBFD ROs

Paragraph 17. A method according to any of Paragraphs 14 to 16, wherein the at least one characteristic of the first RO is a preamble set to which the PRACH preamble transmitted in the first RO belongs.

Paragraph 18. A method according to Paragraph 17, comprising determining, if the preamble set is a first preamble set, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, determining, if the preamble set is a second preamble set, that all of the one or more other ROs are SBFD ROs, or determining, if the preamble set is a third preamble set, that all of the one or more other ROs are non-SBFD ROs.

Paragraph 1 . A method according to Paragraph 17, comprising determining, if the preamble set is a first preamble set, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the preamble set is a second preamble set, either that all of the one or more other ROs are SBFD ROs if the first RO is an SBFD RO, or that all of the one or more other ROs are non-SBFD ROs if the first RO is a non-SBFD RO.

Paragraph 20. A method according to any of Paragraphs 14 to 19, wherein the at least one characteristic of the first RO is a frequency resource of the first RO.

Paragraph 21. A method according to Paragraph 20, comprising determining, if the frequency resource of the first RO is a first frequency resource, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, determining, if the frequency resource of the first RO is a second frequency resource, that all of the one or more other ROs are SBFD ROs, or determining, if the frequency resource of the first RO is a third frequency resource, that all of the one or more other ROs are non-SBFD ROs.

Paragraph 22. A method according to Paragraph 20, comprising determining, if the frequency resource of the first RO is a first frequency resource, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the frequency resource of the first RO is a second frequency resource, either that, that all of the one or more other ROs are SBFD ROs if the first RO is an SBFD RO, or that all of the one or more other ROs are non-SBFD ROs if the first RO is a non-SBFD RO

Paragraph 23. A method according to any of Paragraphs 14 to 22, wherein the first RO is an SBFD RO and the at least one characteristic of the first RO is a type of configuration of the first RO.

Paragraph 24. A method according to Paragraph 23, comprising determining, if the type of configuration was a separate PRACH configuration for use only by SBFD-capable communications devices, that the one or more other ROs are either SBFD ROs or non- SBFD ROs.

Paragraph 25. An infrastructure equipment forming part of a wireless communications network, the infrastructure equipment comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to receive, from the communications device in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of a random access procedure performed by the communications device with the infrastructure equipment, and to determine, based on at least one characteristic of the first RO, one or more other ROs in which the infrastructure equipment is to receive repetitions of the PRACH preamble from the communications device, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface. Paragraph 26. Circuitry for an infrastructure equipment forming part of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to receive, from the communications device in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of a random access procedure performed by the communications device with the infrastructure equipment, and to determine, based on at least one characteristic of the first RO, one or more other ROs in which the infrastructure equipment is to receive repetitions of the PRACH preamble from the communications device, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface. Paragraph 27. A wireless communications system comprising a communications device according to Paragraph 12 and an infrastructure equipment according to Paragraph 25.

Paragraph 28. A method of operating a communications device configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, the method comprising receiving, from the infrastructure equipment, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, and determining, based on an indication contained within the PDCCH order, a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment, wherein the indication contained within the PDCCH order indicates either: that the plurality of ROs are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

Paragraph 29. A communications device, the communications device being a sub-band full duplex, SBFD, capable communications device and comprising transceiver circuitry configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, and controller circuitry configured in combination with the transceiver circuitry to receive, from the infrastructure equipment, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, and to determine, based on an indication contained within the PDCCH order, a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment, wherein the indication contained within the PDCCH order indicates either: that the plurality of ROs are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

Paragraph 30. Circuitry for a communications device, the communications device being a sub-band full duplex, SBFD, capable communications device, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, and controller circuitry configured in combination with the transceiver circuitry to receive, from the infrastructure equipment, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, and to determine, based on an indication contained within the PDCCH order, a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment, wherein the indication contained within the PDCCH order indicates either: that the plurality of ROs are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs. Paragraph 31. A method of operating an infrastructure equipment forming part of a wireless communications network and configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, the method comprising transmitting, to the communications device, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, wherein an indication contained within the PDCCH order indicates either: that a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

Paragraph 32. An infrastructure equipment forming part of a wireless communications network, the infrastructure equipment comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, wherein an indication contained within the PDCCH order indicates either: that a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

Paragraph 33. Circuitry for an infrastructure equipment forming part of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, wherein an indication contained within the PDCCH order indicates either: that a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

Paragraph 34. A wireless communications system comprising a communications device according to Paragraph 29 and an infrastructure equipment according to Paragraph 32.

Paragraph 35. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to any of Paragraphs 1 to 11, Paragraphs 14 to 24, Paragraph 28, or Paragraph 31.

Paragraph 36. A non-transitory computer-readable storage medium storing a computer program according to Paragraph 35.

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

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

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

References

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

[2] TR 38.913, “3^rd Generation Partnership Project; Technical Specification Group Radio Access Network; Study on Scenarios and Requirements for Next Generation Access Technologies

(Release 14)”, 3GPP, vl4.3.0, August 2017.

[3] RP -213591, “New SI: Study on evolution of NR duplex operation,” CMCC, RAN#94e, December 2021.

[4] RP -220633, “Revised SID: Study on evolution of NR duplex operation,” CMCC, RAN#95e, March 2022.

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

[6] European Patent No. 3545716.

[7] TS 38.211 “Physical channels and modulation (Rel-18),” 3GPP, V18.0.0, September 2023. [8] TS 38.213, “Physical layer procedures for control (Rel-18),” 3GPP, V18.0.0, September 2023.

[9] European patent application number EP24155834.5.

[10] Rl-2403242, “Discussion on SBFD random access operation,” NTT DOCOMO, RAN1#116bis, April 2024.

Claims

CLAIMS What is claimed is:

1. A method of operating a communications device configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, the method comprising determining that the communications device is to perform a random access procedure with the infrastructure equipment, transmitting, to the infrastructure equipment in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of the random access procedure, and determining, based on at least one characteristic of the first RO, one or more other ROs in which the communications device is to transmit repetitions of the PRACH preamble to the infrastructure equipment, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface.

2. A method according to Claim 1, wherein the at least one characteristic of the first RO is a type of symbols within which the first RO is transmitted.

3. A method according to Claim 2, comprising determining, if the type of symbols within which the first RO is transmitted is an SBFD symbol, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the type of symbols within which the first RO is transmitted is a non-SBFD uplink symbol, that all of the one or more other ROs are non-SBFD ROs

4. A method according to Claim 1, wherein the at least one characteristic of the first RO is a preamble set to which the PRACH preamble transmitted in the first RO belongs.

5. A method according to Claim 4, comprising determining, if the preamble set is a first preamble set, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, determining, if the preamble set is a second preamble set, that all of the one or more other ROs are SBFD ROs, or determining, if the preamble set is a third preamble set, that all of the one or more other ROs are non-SBFD ROs.

6. A method according to Claim 4, comprising determining, if the preamble set is a first preamble set, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the preamble set is a second preamble set, either that all of the one or more other ROs are SBFD ROs if the first RO is an SBFD RO, or that all of the one or more other ROs are non-SBFD ROs if the first RO is a non-SBFD RO.

7. A method according to Claim 1, wherein the at least one characteristic of the first RO is a frequency resource of the first RO.

8. A method according to Claim 7, comprising determining, if the frequency resource of the first RO is a first frequency resource, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, determining, if the frequency resource of the first RO is a second frequency resource, that all of the one or more other ROs are SBFD ROs, or determining, if the frequency resource of the first RO is a third frequency resource, that all of the one or more other ROs are non-SBFD ROs.

9. A method according to Claim 7, comprising determining, if the frequency resource of the first RO is a first frequency resource, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the frequency resource of the first RO is a second frequency resource, either that, that all of the one or more other ROs are SBFD ROs if the first RO is an SBFD RO, or that all of the one or more other ROs are non-SBFD ROs if the first RO is a non-SBFD RO.

10. A method according to Claim 1, wherein the first RO is an SBFD RO and the at least one characteristic of the first RO is a type of configuration of the first RO.

11. A method according to Claim 8, comprising determining, if the type of configuration was a separate PRACH configuration for use only by SBFD-capable communications devices, that the one or more other ROs are either SBFD ROs or non- SBFD ROs.

12. A communications device, the communications device being a sub-band full duplex, SBFD, capable communications device and comprising transceiver circuitry configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, and controller circuitry configured in combination with the transceiver circuitry to determine that the communications device is to perform a random access procedure with the infrastructure equipment, to transmit, to the infrastructure equipment in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of the random access procedure, and to determine, based on at least one characteristic of the first RO, one or more other ROs in which the communications device is to transmit repetitions of the PRACH preamble to the infrastructure equipment, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface.

13. Circuitry for a communications device, the communications device being a sub-band full duplex, SBFD, capable communications device, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, and controller circuitry configured in combination with the transceiver circuitry to determine that the communications device is to perform a random access procedure with the infrastructure equipment, to transmit, to the infrastructure equipment in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of the random access procedure, and to determine, based on at least one characteristic of the first RO, one or more other ROs in which the communications device is to transmit repetitions of the PRACH preamble to the infrastructure equipment, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface.

14. A method of operating an infrastructure equipment forming part of a wireless communications network and configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, the method comprising receiving, from the communications device in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of a random access procedure performed by the communications device with the infrastructure equipment, and determining, based on at least one characteristic of the first RO, one or more other ROs in which the infrastructure equipment is to receive repetitions of the PRACH preamble from the communications device, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface.

15. A method according to Claim 14, wherein the at least one characteristic of the first RO is a type of symbols within which the first RO is transmitted.

16. A method according to Claim 15, comprising determining, if the type of symbols within which the first RO is transmitted is an SBFD symbol, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the type of symbols within which the first RO is transmitted is a non-SBFD uplink symbol, that all of the one or more other ROs are non-SBFD ROs

17. A method according to Claim 14, wherein the at least one characteristic of the first RO is a preamble set to which the PRACH preamble transmitted in the first RO belongs.

18. A method according to Claim 17, comprising determining, if the preamble set is a first preamble set, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, determining, if the preamble set is a second preamble set, that all of the one or more other ROs are SBFD ROs, or determining, if the preamble set is a third preamble set, that all of the one or more other ROs are non-SBFD ROs.

19. A method according to Claim 17, comprising determining, if the preamble set is a first preamble set, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the preamble set is a second preamble set, either that all of the one or more other ROs are SBFD ROs if the first RO is an SBFD RO, or that all of the one or more other ROs are non-SBFD ROs if the first RO is a non-SBFD RO.

20. A method according to Claim 14, wherein the at least one characteristic of the first RO is a frequency resource of the first RO.

21. A method according to Claim 20, comprising determining, if the frequency resource of the first RO is a first frequency resource, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, determining, if the frequency resource of the first RO is a second frequency resource, that all of the one or more other ROs are SBFD ROs, or determining, if the frequency resource of the first RO is a third frequency resource, that all of the one or more other ROs are non-SBFD ROs.

22. A method according to Claim 20, comprising determining, if the frequency resource of the first RO is a first frequency resource, that the one or more other ROs are either SBFD ROs or non-SBFD ROs, or determining, if the frequency resource of the first RO is a second frequency resource, either that, that all of the one or more other ROs are SBFD ROs if the first RO is an SBFD RO, or that all of the one or more other ROs are non-SBFD ROs if the first RO is a non-SBFD RO.

23. A method according to Claim 14, wherein the first RO is an SBFD RO and the at least one characteristic of the first RO is a type of configuration of the first RO.

24. A method according to Claim 23, comprising determining, if the type of configuration was a separate PRACH configuration for use only by SBFD-capable communications devices, that the one or more other ROs are either SBFD ROs or non- SBFD ROs.

25. An infrastructure equipment forming part of a wireless communications network, the infrastructure equipment comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to receive, from the communications device in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of a random access procedure performed by the communications device with the infrastructure equipment, and to determine, based on at least one characteristic of the first RO, one or more other ROs in which the infrastructure equipment is to receive repetitions of the PRACH preamble from the communications device, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface.

26. Circuitry for an infrastructure equipment forming part of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to receive, from the communications device in a first physical random access channel, PRACH, occasion, RO, a PRACH preamble as part of a random access procedure performed by the communications device with the infrastructure equipment, and to determine, based on at least one characteristic of the first RO, one or more other ROs in which the infrastructure equipment is to receive repetitions of the PRACH preamble from the communications device, wherein one or more of the first RO and other ROs are SBFD ROs which are contained within SBFD symbols of the radio access interface and/or one or more of the first RO and other ROs are non- SBFD ROs which are contained within non-SBFD uplink symbols of the radio access interface.

27. A wireless communications system comprising a communications device according to Claim 12 and an infrastructure equipment according to Claim 25.

28. A method of operating a communications device configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, the method comprising receiving, from the infrastructure equipment, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, and determining, based on an indication contained within the PDCCH order, a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment, wherein the indication contained within the PDCCH order indicates either: that the plurality of ROs are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

29. A communications device, the communications device being a sub-band full duplex, SBFD, capable communications device and comprising transceiver circuitry configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, and controller circuitry configured in combination with the transceiver circuitry to receive, from the infrastructure equipment, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, and to determine, based on an indication contained within the PDCCH order, a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment, wherein the indication contained within the PDCCH order indicates either: that the plurality of ROs are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

30. Circuitry for a communications device, the communications device being a sub-band full duplex, SBFD, capable communications device, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a radio access interface between the communications device and the infrastructure equipment, and controller circuitry configured in combination with the transceiver circuitry to receive, from the infrastructure equipment, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, and to determine, based on an indication contained within the PDCCH order, a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment, wherein the indication contained within the PDCCH order indicates either: that the plurality of ROs are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

31. A method of operating an infrastructure equipment forming part of a wireless communications network and configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, the method comprising transmitting, to the communications device, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, wherein an indication contained within the PDCCH order indicates either: that a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

32. An infrastructure equipment forming part of a wireless communications network, the infrastructure equipment comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, wherein an indication contained within the PDCCH order indicates either: that a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

33. Circuitry for an infrastructure equipment forming part of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and/or to receive signals from a communications device via a radio access interface between the communications device and the infrastructure equipment, the communications device being a sub-band full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, a physical downlink control channel, PDCCH, order, wherein the PDCCH order indicates that the communications device is to transmit a physical random access channel, PRACH, preamble to the infrastructure equipment in accordance with an indicated number of repetitions, wherein an indication contained within the PDCCH order indicates either: that a plurality of PRACH, occasion, ROs, in which the communications device is to transmit the repetitions of the PRACH preamble to the infrastructure equipment are to comprise only SBFD ROs which are contained within SBFD symbols of the radio access interface, that the plurality of ROs are to comprise only non-SBFD ROs which are contained within non- SBFD uplink symbols of the radio access interface, or that the plurality of ROs can comprise a mixture of SBFD ROs and non-SBFD ROs.

34. A wireless communications system comprising a communications device according to Claim 29 and an infrastructure equipment according to Claim 32.

35. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to Claim 1 , Claim 14, Claim 28, or Claim 31.

36. A non-transitory computer-readable storage medium storing a computer program according to Claim 35.