WO2026027262A1 - 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 subband full duplex (SBFD) capable communications device. The method comprises receiving, from the infrastructure equipment, a physical random access channel (PRACH) configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, determining that the slot containing the set of ROs is an SBFD slot, and determining, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration.

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 invention claims the Paris Convention priority from European patent application number EP24192205.3, filed on 31 July 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.

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 subband full duplex, SBFD, capable communications device. The method comprises receiving, from the infrastructure equipment, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, determining that the slot containing the set of ROs is an SBFD slot, and determining, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration.

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 subbands for uplink and downlink transmissions for subband full duplex (SBFD); Figure 5 schematically represents second and third examples of non-overlapping subbands 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 shows how an SBFD RO may be configured outside of an UL SBFD subband based on the parameter msgl -FrequencyStart,

Figure 16 shows how reinterpreting the parameter msgl -FrequencyStart such that it is defined with respect to the start of an UL SBFD subband rather than with respect to the start of the slot can lead to an SBFD RO being configured outside of the slot;

Figure 17 illustrates a first example of how re-interpreting the parameter msgl -FrequencyStart based on application of a MOD function can lead to SBFD ROs being wholly contained within an UL SBFD subband but where the SBFD ROs may not be contiguous;

Figure 18 illustrates a second example of how re-interpreting the parameter msgl -FrequencyStart based on application of a MOD function can lead to SBFD ROs being wholly contained within an UL SBFD subband but where there may be a collision between some of the SBFD ROs;

Figure 19 shows a part schematic, part message flow diagram representation of an example wireless communications system comprising a communications device and an infrastructure equipment in accordance with embodiments of the present technique;

Figure 20 illustrates an example of how the number of SBFD ROs within an SBFD slot may be reinterpreted to ensure that all SBFD ROs are wholly contained within an UL SBFD subband with no collision between any of the SBFD ROs in accordance with embodiments of the present technique;

Figure 21 illustrates an example of how the location of a set of SBFD ROs within an SBFD slot may be reinterpreted using a first technique to ensure that all SBFD ROs are wholly contained within an UL SBFD subband in a contiguous manner;

Figure 22 illustrates an example of how the location of a set of SBFD ROs within an SBFD slot may be reinterpreted using a second technique to ensure that all SBFD ROs are wholly contained within an UL SBFD subband in a contiguous manner; and

Figure 23 shows a flow diagram illustrating an example process of communications in a communications system in accordance with embodiments of the present technique.

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

Subband 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 subbands, where each subband can be DL or UL [6], Guard subbands may be used between DL and UL subbands to reduce inter subband interference. In the current 5G system, only one UL subband 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 subbands 61 to 63, i.e. in different sets of frequency Resource Blocks (RB): Subband# 1 61, Subband#2 62, Subband#3 63. The example of Figure 4 is referred to as {DUD}, because two subbands, Subband# 1 61 and Subband#3 63, are used for DL transmissions whilst one subband, Subband#2 62, is used for UL transmissions. To reduce leakage from one subband 61 to 63 to another, a guard subband 64 may be configured between UL and DL subbands 61 to 63. Guard subbands 64 are configured between DL Subband#3 63 and UL Subband#2 62 and between UL Subband#2 62 and DL Subband# 1 61.

Figure 5 shows two further examples with a DL and UL subband separated by a guard subband, where here, the UL subband can be configured to occupy the lower frequency portion of the BWP whilst the DL subband occupies higher frequency portion of the BWP {UD} or the UL subband occupies the higher frequency portion of the BWP whilst the DL subband occupies lower frequency portion of the BWP {DU}. Here, on the left-side of Figure 5, an UL subband# 1 71 is separated from a DL subband#2 73 by a guard subband 72 - this subband arrangement is referred to as {UD}. In this case, the DL subband#2 73 occupies a higher frequency portion of the system bandwidth than the UL subband# 1 71. On the rightside of Figure 5, a DL subband# 1 81 is separated from an UL subband#2 83 by a guard subband 82 - this subband arrangement is referred to as {DU} . In this case, the UL subband#2 83 occupies a higher frequency portion of the system bandwidth than the DL subband# 1 81. While Figures 4 and 5 show the system bandwidth as being divided into either two or three subbands, 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 subbands could be used, if deemed beneficial. For example, the system bandwidth may be divided into four subbands, which may, using the example of Figure 4, include the two downlink subbands 61, 63, the uplink subband 62 and another uplink subband, though other subband arrangements are envisioned. Guard subbands may be used in substantially any subband 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 Demodulation Reference Signals (DMRS) are 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 using the parameter msgl-FDM= { 1, 2, 4, 8} FDM ROs for UEs. The start of the first RO is indicated by the network using the RRC parameter msgl -FrequencyStart, and the rest of the ROs are sequentially mapped one after the other in the frequency domain.

As mentioned above, ROs are configured in communications resources of a wireless access interface. Communications resources are comprised of time resources and frequency resources. The time resources of the ROs in a PRACH Occasion configuration are determined by a “PRACH Configuration Index”, which is an index to Tables 6.3.3.2-2, 6.3.3.2-3 and 6.3.3.2-4 in [7], which is hereby incorporated by reference in its entirety. There are 256, 263 and 256 PRACH configurations for FR1 FDD, FR1 TDD and FR2 respectively. The PRACH configuration index indicates a PRACH preamble format, a PRACH periodicity (known as a “PRACH Configuration Period”), a number of PRACH Occasions within a PRACH period, the starting symbol of the PRACH Occasion in a slot and a duration of the PRACH Occasion.

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 x 7 time domain ROs x 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 9A 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 I: PRACH Configuration Period and SSB-RO association period (reproduced from [8])

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.

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 below, which reproduces a portion of this lookup table in Table 6.3.3.2-3 of [7],

Table II: PRACH Configuration Index 129 (reproduced from [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 x 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 fully 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 NPRACH 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 NPRACH =4 ROs are RO#3 in SFN k, SFN k + 2, SFN k + 4 and SFN k + 6, which are outlined in dashed boxes in 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 subbands 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 subband 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} subband 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 + 1. 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.

Table III: Dual PRACH configurations for legacy TDD and SBFD RACH

Here, the SBFD UE also performs two SSB-RO associations 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 a second 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 IV: PRACH Configuration Indices 125 and 127 (reproduced from [7]) Technical Issue

The benefit of configuring SBFD ROs using the single PRACH configuration is that it can use the same PRACH configuration as that used for legacy operations. However, since legacy ROs are configured in UL OFDM symbols, the legacy ROs may be configured outside of the UL subband.

An example is shown in Figure 15, where the same PRACH configuration as that used in the example in Figure 13, i.e., PRACH Configuration Index = 129 (as shown in Table II), is used in the example of Figure 15, along with the parameter msgl -FDM = 2. The ROs under PRACH Configuration Index = 129 are in Subframes 3, 4, 8 and 9, where for legacy UEs, Subframe 3 and 8 are DL slots, and therefore the ROs in these slots are invalid as shown in Figure 15. That is, for legacy UEs, only ROs in UL slots, i.e., those in Subframes 4 and 9, are valid, and they are labelled as RO#1 to RO#7. The frequency location of the ROs is configured using the parameter msgl -FrequencyStart, which indicates the RB offset between the first FDM RO and the first RB in the BWP. In the example shown in Figure 15, msgl- FrequencyStart is configured such that the ROs are at the upper edge of the BWP. If a {DUD} SBFD subband is configured on the DL slots of the TDD pattern, then the ROs in SBFD slots, i.e., those in Subframe 3 and Subframe 8, may not be contained within the UL subband, which would not lead to any increase in RO capacity.

In [10], it is proposed that the network should be responsible for ensuring that the ROs are contained within the UL subband. That is, the network should ensure that the parameter msgl -FrequencyStart is configured such that it places the ROs in frequencies that are in the UL subband, even for legacy ROs in UL slots, since the parameter msgl -FrequencyStart defines the starting frequency of the first RO for all ROs regardless of whether they are in SBFD OFDM symbols or UL OFDM symbols. However, it is argued in [11] that the ROs are typically scheduled at the edge of the BWP to avoid fragmenting PUSCH resources, and so for {DUD} SBFD subband configuration, the ROs may not fall within the central UL subband.

In [11], it is proposed that the parameter msgl -FrequencyStart is reinterpreted for SBFD UEs such that msgl -FrequencyStart is relative to the first RB of the UL subband instead of the first RB of the entire BWP. That is:

RBk-uL — msgl -FrequencyStart + RBUL subband (1) where:

• RBk-uL is the reinterpreted msgl -FrequencyStart which references the UL subband; and

• RBuL subband is the start of the UL subband.

However, changing the reference point for msgl -FrequencyStart may not place ROs within the UL subband, and it may even shift the ROs outside of the BWP. An example is shown in Figure 16, where the PRACH Configuration Index used for legacy UEs has ROs in DL slots, e.g., Slot n. The parameter msgl -Frequency Star is configured such that the ROs are at the upper edge of the BWP. Using the method proposed in [11] to reinterpret the reference point of msgl -FrequencyStart for SBFD slots would move the ROs outside of the BWP in the SBFD slot as shown in Slot n of Figure 16. Clearly, this would be an issue.

In [12] and [13], it is proposed that a modulus (MOD) function is used to ensure that the ROs are within the UL subband. Specifically in [13], the start of each FDM RO is determined as: RBk — RBijL subband + RB_o-k MOD (NijL subband ~ NRQ) (2) where:

• RBk is the reinterpreted start of the FDM RO with reference to the start of the BWP;

• RBuL subband is the starting RB of the UL subband;

• RB_o.k is the start of the legacy IF FDM RO;

• NuL Mand is the frequency size of the UL subband in number of RBs; and

• NRO is the frequency size of an RO in number of RBs.

An example using the method proposed in [13] is shown in Figure 17, which has the same configuration as the example in Figure 16. In this example the ROs in the SBFD Slot n are fully contained within the UL subband due to the MOD function. Any ROs that would otherwise fall outside of the UL subband, for example RO#2 and RO#4 in the example of Figure 17, would be wrapped around within the UL subband due to the MOD function.

An issue identified with the RO wrap-around method using the MOD function is that it may cause intra- PRACH slot RO collisions. This can occur if the RO that is wrapped around collides with a lower frequency FDM RO, which is likely for a small UL subband configured with a large number of FDM ROs and a short format preamble at a higher subcarrier spacing (SCS), e.g. 12 RB ROs at 60 kHz SCS or 120 kHz SCS.

An example is shown in Figure 18, where the parameter msgl-FDM= 4, and it is assumed that the UE operates in a higher SCS such as 60 kHz with an RO occupying 12 RBs. Using the method proposed in [13], the first three pairs of ROs are contained within the UL subband in SBFD Slot n, and as per this method, the fourth pair of FDM ROs, i.e., RO#4 and RO#8, is wrapped around to the beginning of the UL subband. However, the wrapped around RO#4 and RO#8 collides 90 with the lower frequency pair of FDM ROs, i.e., RO#1 and RO#5.

Another issue with wrapped around ROs is this will fragment the RO resources. The legacy RO resources are contiguous in the frequency domain, and wrapped around ROs would split/fragment these resources which may not be desirable for gNB scheduler. For example, as shown in the example of Figure 17, there is a gap (in frequency) between the ROs already placed within the UL subband before application of the MOD function (i.e. RO#1 and RO#3) and the wrapped-around ROs (i.e. RO#2 and RO#4).

Hence, the technical problem to solve is how to resolve the issues of RO collisions and fragmentation within a PRACH slot due to the reinterpretation of the parameter msgl-FrequencyStart performed in order to contain ROs within the UL subband. Various arrangements of embodiments of the present technique propose solutions to such a problem, and enable the more effective and efficient transmission of uplink signals by UEs within SBFD subbands.

Adjustment of FDM ROs for SBFD PRACH

Figure 19 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 subband full duplex, SBFD, capable communications device (SBFD UE), meaning that it is able to understand SBFD configurations using configured SBFD UL and DL subbands. The communications device 101 may be configured to transmit signals to and/or receive signals from the wireless communications network (where transmitting and receiving are not performed at the same time by the communications device that operates in a half-duplex manner), 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 (non-simultaneously) 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 19).

As shown in the example of Figure 19, the controller 101.2 of the communications device 101 is configured to control the transceiver 101.1 of the communications device 101 to receive 103, from the infrastructure equipment 102, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device 101 is able to transmit PRACH preambles to the infrastructure equipment 102, wherein the PRACH configuration 103 indicates each of a first parameter (e.g. msgl-FDM) that defines a number of the ROs in the set of ROs and a second parameter (e.g. msgl-FrequencyStart) that defines a location of the set of ROs within the slot (e.g. by defining a frequency offset between the slot boundary and the set of ROs), to determine 104 that the slot containing the set of ROs is an SBFD slot, and to determine 105, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration.

Here, the set of ROs may be configured by the PRACH indication across more than one slot, where each of these slots has the same frequency resource configuration, with the same number of FDMed ROs (i.e. the first parameter is consistent when the PRACH configuration is applied across multiple slots) and in the same location in each of those slots (i.e. the second parameter is consistent when the PRACH configuration is applied across multiple slots).

The communications device 101 may at some point (e.g. before determining 104 that the slot is an SBFD slot, after determining 104 that the slot is an SBFD slot but before determining 105 that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration, or after determining 105 that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration) that the communications device 101 is to perform a random access procedure with the infrastructure equipment 102. Upon so doing, the communications device 101 may then transmit - after having determining 105 that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration - a PRACH preamble to the infrastructure equipment 102 as part of the random access procedure in at least one of the set of ROs, where those ROs (in terms of their number and/or location within the slot) have been reinterpreted by the communications device 101. Here, the PRACH preamble may be transmitted once in a single RO (i.e. one of the new set of ROs), or the PRACH preamble may be transmitted in accordance with PRACH repetitions. These repetitions of the PRACH preamble may be performed by transmitting the preamble in ROs configured within one or more subsequent slots.

As those skilled in the art would appreciate, since the communications device 101 reinterprets the first parameter and/or the second parameter, the communications device 101 considers the set of ROs to be in a different position within the SBFD slot and/or the communications device 101 considers the number of ROs in the set to be different with respect to what has been configured by the infrastructure equipment in the PRACH configuration 103 (which, as discussed above, may be the single PRACH configuration that configures both SBFD ROs and legacy ROs). Therefore, when the communications device 101 transmits PRACH preambles in these ROs, the network has to be aware that the communications device 101 will do this based on the reinterpretation having been performed. Accordingly, it will be necessary for the infrastructure equipment to perform the exact same reinterpretation as the communications device 101.

In other words, and as shown in the example of Figure 19, the controller 102.2 of the infrastructure equipment 102 is configured to control the transceiver 102.1 of the infrastructure equipment to transmit 103, to the communications device 101, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device 101 is able to transmit PRACH preambles to the infrastructure equipment 102, wherein the PRACH configuration 103 indicates each of a first parameter (e.g. msgl- FDM) that defines a number of the ROs in the set of ROs and a second parameter (e.g. msgl- FrequencyStart) that defines a location of the set of ROs within the slot (e.g. by defining a frequency offset between the BWP boundary in the slot and the set of ROs), to determine 104 that the slot containing the set of ROs is an SBFD slot, and to determine 105, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration.

Essentially then, embodiments of the present technique, as exemplified by the example wireless communications system of Figure 19 for example, propose that SFBD UEs (and, correspondingly, the network) should reinterpret msgl -FDM differently in addition to msgl -FrequencySiari. for example using an equation or scaling factor, so that the configured ROs can fit into the frequency resources of the UL subband, without causing the issues of collisions between ROs or the fragmentation of contiguously configured ROs.

While this reinterpretation may cause the reinterpretation (e.g. the determination of new values) for only msgl -FDM, for only msgl-FrequencyStart, or for both FDM and msgl -FrequencyStart, the reinterpretation is always based on a consideration of the configured value of msgl -FDM, in contrast to the prior art solutions described in [10], [11], [12], and [13], for example. That is, while in some embodiments of the present technique the configured value of msgl -FDM itself is reinterpreted (i.e. changed) by SBFD UEs/the network, in other embodiments of the present technique where only msgl- FrequencyStart is reinterpreted (i.e. changed) by SBFD UEs/the network, this reinterpretation/change is applied in a manner which is dependent on the configured value of msgl -FDM. This is described in greater detail below.

It should be appreciated by those skilled in the art that arrangements of embodiments of the present disclosure may be applied in addition to previously disclosed methods for the reinterpretation of msgl- FrequencyStart (e.g. such as those described in [13], or those in which ROs are removed or invalidated to overcome collisions and fragmentation). As described in greater detail below, the reinterpreted msgl- FrequencyStart can be expressed in the form of either RBm or RBt. That is, the reinterpreted msgl- FrequencyStart when expressed as RBk-uL would always reference the start of the UL subband, whereas when it is expressed as RBk, it would instead reference the start of the UL BWP (e.g. the current SBFD slot). Accordingly, it would be appreciated by those skilled in the art that any calculation when performing reinterpretations of msgl-FrequencyStart (i.e., the first parameter as defined in the claims) would need to include consideration of RBuL_subband (as described above with respect to equations (1) and (2)). Both definitions of the reinterpreted msgl -FrequencyStart are applicable to arrangements of embodiments of the present technique as described herein.

In some arrangements of embodiments of the present technique, the reinterpretation of msgl -FDM is to scale the number of FDMed ROs. In other words, determining that at least one of the first parameter and the second parameter is to be interpreted differently may comprise the communications device (and/or infrastructure equipment) being configured to perform a scaling operation on a configured value of the first parameter to define a smaller number of ROs in the set of ROs than configured by the PRACH configuration.

An example for scaling the number of FDMed ROs is to scale it in proportion to a ratio of UL subband bandwidth compared to entire UL bandwidth. In other words, the scaling operation may comprise scaling the configured value of the first parameter by an amount dependent on a ratio of a bandwidth of an uplink subband of the SBFD slot to a bandwidth of a non-SBFD uplink slot.

An example is shown in Figure 20, where the entire UL bandwidth in an UL slot is, for example, 50 PRBs and the bandwidth of an UL subband in a SBFD slot is, for example, 25 PRBs. The example of Figure 20 is not shown to this scale, but these are example bandwidth values provided for ease of understanding. As can be seen in the example of Figure 20, msgl-FDM= 4 for the UL slot, and therefore the number of FDMed ROs is scaled by 1/2, i.e., resulting in an FDM of 2, which is calculated by msgl- FDM x (25 / 50). Therefore, the ROs in slot n are numbered from RO#1 to RO#4, and the ROs in slot «+l are numbered from RO#5. This would be beneficial as it enables the reserving of UL resources for other UL transmissions in the UL subband. It should be appreciated that other scaling based on this ratio is feasible; for example, there may be a constant K_FDM applied to the ratio, i.e., scaled by K_FDM x (UL subband bandwidth/UL BWP bandwidth). In general, the scaling is a function of the ratio of the UL subband size and the UL BWP size.

In some arrangements of embodiments of the present technique, the said scaling is done if the frequency resources occupied by the FDM RO cannot fit into the UL subband. In other words, the scaling operation may be performed based on the communications device and/or infrastructure equipment determining that there is not sufficient space in an uplink subband of the SBFD slot for all of the set of ROs configured by the PRACH configuration. This can be done by comparing the bandwidth of the FDM ROs against that of the UL subband. That is, if the bandwidth of the FDM ROs is bigger than the bandwidth of the UL subband, then scaling is performed; otherwise scaling is not performed. For example, if the UL subband is 20 PRBs and each RO is 6 RBs, with FDM = 4, then the total FDM RO frequency resources = 24 RBs, which is greater than the size of the UL subband. Hence, scaling is performed (for example, as described in the previously described arrangements).

In some arrangements of embodiments of the present technique, the reinterpretation of msgl -FDM is to maximise the number of FDM ROs from msgl -FDM as much as possible into the UL subband. In other words, the scaling operation may comprise scaling the configured value of the first parameter by an amount dependent on a maximum number of the set of ROs that can fit in an uplink subband of the SBFD slot. In one implementation of such arrangements, a ROUNDDOWN function is used to adjust the number of FDM RO such that it is maximized to fit within the UL subband, where the function ROUNDDOWN rounds down to the nearest integer. That is:

RO_PDM = MIN(ROUNDDOWN(N_{UL subband} !N_RO), msg 1 FDM) (3) where:

• ROFDM is the maximum number of FDM ROs that can fit within the UL subband;

• NUL subband IS the frequency size of the UL subband in terms of the number of RBs;

• NRO is the frequency size of an RO in terms of the number of RBs; and

• msglFDM = msgl-FDM configured by RRC = { 1, 2, 4, 8} .

In some arrangements of embodiments of the present technique, the RO frequency location parameter msgl -FrequencyStart is reinterpreted such that it is does not cause wrapped-around ROs. Such arrangements recognise that wrapped-around ROs causes fragmentation of RO resources in the frequency domain. Assuming that the number of FDM ROs can fit within the UL subband, the RO frequency location (e.g., the starting position/starting RB within the UL subband) can be simply reinterpreted to avoid ROs being wrapped around. In other words, determining that at least one of the first parameter and the second parameter is to be interpreted differently may comprise the communications device and/or the infrastructure equipment being configured to determine that the second parameter defines a starting frequency position within an uplink subband of the SBFD slot that enables all of the set of ROs to fit into the uplink subband.

In the case where the number of FDM ROs cannot fit within the UL subband, the RO frequency location (e.g. the starting position/starting RB within the UL subband) can still be reinterpreted to avoid ROs being wrapped around. However, scaling of the number of FDMed ROs will then need to be performed in addition to avoid any collisions or any ROs falling outside the other boundary of the UL subband. Such scaling can be performed in any appropriate manner as described above with respect arrangements of embodiments of the present technique. In other words, determining that at least one of the first parameter and the second parameter is to be interpreted differently may further comprise the communications device and/or infrastructure equipment being configured to perform (prior to determining that the second parameter defines the starting frequency position), if there is not sufficient space in the uplink subband for all of the set of ROs configured by the PRACH configuration, a scaling operation on a configured value of the first parameter to define a smaller number of ROs in the set of ROs than configured by the PRACH configuration.

In at least some implementation of such arrangements, the said reinterpreted parameter msgl- FrequencyStart that shifts the starting frequency position for the FDM ROs is expressed in the following equation: where:

• RBstart is the reinterpreted start (i.e. starting frequency position) of the msgl -FrequencyStart with reference to the start of the BWP;

• RBuL_su_bband is the starting RB of the UL subband; NUL IS the frequency size of the UL subband in terms of the number of RBs; NRO is the frequency size of an RO in terms of the number of RBs; and msglFDM = msgl-FDM configured by RRC = { 1, 2, 4, 8} .

In other words, in such implementations, the starting frequency position may be defined with respect to a starting frequency of the SBFD slot.

In at least some other implementations of such arrangements, equation (4) as defined above can also express the reinterpreted parameter msgl -FrequencyStart as instead of Here, where is the reinterpreted start (i.e. starting frequency position) of the msgl -FrequencyStart with reference to the start of the BWP, RB_start-uL is similar to RBUUL and is therefore the reinterpreted start (i.e. starting frequency position) of the msgl -FrequencyStart with reference to the start of the UL subband. That is: * NRO, (5)

In other words, in such implementations, the starting frequency position may be defined with respect to a starting frequency of the uplink subband.

Here, in each of equations (4) and (5), there are two checks performed which determine how the reinterpretation of msgl -FrequencyStart is performed. Firstly, it is determined whether there is enough space in the UL subband to fit the configured set of ROs. If so, then the starting frequency position of these ROs is determined as a particular point or RB (relative to either the start of the UL subband or the start of the SBFD slot) that would allow all ROs to then fit in the UL subband up to the upper frequency boundary of the UL subband. However, if this first check is failed, then a second check is performed, which effectively involves the determination that at least one RO will fit in the UL subband (i.e. the RO bandwidth is less than the UL subband bandwidth), and if so, then scaling can be performed as described above. If this check is also failed, then no ROs can fit into the UL subband, and so such ROs are deemed invalid.

As described above, and as shown in the examples of Figure 21 (where the reinterpreted parameter msgl- FrequencyStart is expressed as and Figure 22 (where the reinterpreted parameter msgl- FrequencyStart is expressed as the msgl -FrequencyStart for ROs in UL subband of the SBFD symbols/slots is reinterpreted based on the equation above.

As can be seen, in each of the examples shown by Figures 21 and 22, msgl-FDM = 2, 30, 20. Again, each RO is formed of 6 RBs. Hence, the first “ /” condition of equations (4) and (5) are satisfied, where NUL msglFDM * NRO. This means that both ROs can be accommodated inside the UL subband. Hence the starting RB in the example of Figure 21 where it is expressed as = 30 + 20 - 2*6 = 38. Correspondingly, the starting RB in the example of Figure 22 where it is expressed as it is given as = 20 - 2*6 = 8.

It should be appreciated by those skilled in the art that there are different ways of rewriting the above equations (4) and (5) in such a manner that the same result may be achieved. For the case where the reinterpreted parameter msgl -FrequencyStart is expressed as RB_start (e.g. in the example of Figure 21) either equation (4) defined above can be used, or either of equations (6) or (7) defined below can be used instead.

If (A subband msglFDM * NRO), RBstart = RBUL_ subband + NUL_ subband msglFDM * NRO, else RBstart = BUL_ subband + N_UL_ subband RO UNDDO WN(N UL subband /NRO) * NRO (7)

For the case where the reinterpreted parameter msgl -FrequencyStart is expressed as RB_start-uL (e.g. in the example of Figure 22) either equation (5) defined above can be used, or either of equations (8) or (9) defined below can be used instead.

If (AW. subband — msglFDM * NRO), RBstart-UL — NUL_ subband msglFDM * NRO, else RBstart-UL = NUL_ subband RO UNDDO WN(N UL ubband /NRO) * NRO (9)

In the above description, it is assumed ROs that can fit in the UL subband are placed on the upper frequency boundary of the UL subband, as shown in Figures 20, 21, and 22, for example. However, alternatively, if msgl -FrequencyStart starts at the bottom of the UL BWP (i.e., msgl -FrequencyStart = 0) then the reinterpreted parameter msgl -FrequencyStart may also start at the bottom of the UL subband. An example implementation is described in the following two equations (10) and (11), after the number of ROs has been scaled down, e.g., by applying one of the previously described arrangements such as that described with respect to equation (3). That is, if the reinterpreted parameter msgl-FrequencyStart is expressed with respect to the start of the BWP in the slot (i.e. as RB_start), then:

If(N_UL_ subband NRO), RB_start — RBuL subband, else INVALID (10) and if the reinterpreted parameter msgl -FrequencyStart is expressed with respect to the start of the UL subband (i.e. as RB_start-uL), then:

If (AW. subband NRO), RBstart-UL — 0, else INVALID (11)

In the previously described arrangements of embodiments of the present technique, the reinterpreted positions of the ROs either start at the upper edge of the UL subband or at the lower edge of the UL subband. In some other arrangements of embodiments of the present technique, the RO frequency location parameter msgl -FrequencyStart is reinterpreted depending on the location of the original RO position. In an implementation, if the original/legacy RO position as indicated by msgl -FrequencyStart is in the upper half of the UL BWP, then the reinterpreted RO position is placed on the upper edge of the UL subband as described with respect to equations (4) to (9). On the other hand, if the original/legacy RO position as indicated by ms gl -Frequency Start is in the lower half of the UL BWP, then the reinterpreted RO position is placed on the lower edge of the UL subband as described with respect to equation (10) or (11).

Figure 23 shows a flow diagram illustrating an example process of communications in a communications system in accordance with embodiments of the present technique. The process shown by Figure 23 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 subband full duplex, SBFD, capable communications device.

The method begins in step SI. The method comprises, in step S2, receiving, from the infrastructure equipment, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot. In step S3, the process comprises determining that the slot containing the set of ROs is an SBFD slot. The method then comprises, in step S4, determining, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration. The process ends in step S5.

Those skilled in the art would appreciate that the method shown by Figure 23 may be adapted in accordance with embodiments of the present technique. For example, other intermediate steps may be included in such a method, or the steps may be performed in any logical order. Though embodiments of the present technique have been described largely by way of the example communications system shown in Figure 19, and further described with respect to the implementation examples described with respect to Figures 20, 21, and 22, 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.

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 subband full duplex, SBFD, capable communications device, the method comprising receiving, from the infrastructure equipment, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, determining that the slot containing the set of ROs is an SBFD slot, and determining, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration. Paragraph 2. A method according to Paragraph 1, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently comprises performing a scaling operation on a configured value of the first parameter to define a smaller number of ROs in the set of ROs than configured by the PRACH configuration.

Paragraph 3. A method according to Paragraph 2, wherein the scaling operation comprises scaling the configured value of the first parameter by an amount dependent on a ratio of a bandwidth of an uplink subband of the SBFD slot to a bandwidth of a non-SBFD uplink slot.

Paragraph 4. A method according to Paragraph 2 or Paragraph 3, wherein the scaling operation is performed based on the communications device determining that there is not sufficient space in an uplink subband of the SBFD slot for all of the set of ROs configured by the PRACH configuration.

Paragraph 5. A method according to any of Paragraphs 2 to 4, wherein the scaling operation comprises scaling the configured value of the first parameter by an amount dependent on a maximum number of the set of ROs that can fit in an uplink subband of the SBFD slot.

Paragraph 6. A method according to any of Paragraphs 1 to 6, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently comprises determining that the second parameter defines a starting frequency position within an uplink subband of the SBFD slot that enables all of the set of ROs to fit into the uplink subband.

Paragraph 7. A method according to Paragraph 6, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently further comprises performing, prior to determining that the second parameter defines the starting frequency position if there is not sufficient space in the uplink subband for all of the set of ROs configured by the PRACH configuration, a scaling operation on a configured value of the first parameter to define a smaller number of ROs in the set of ROs than configured by the PRACH configuration.

Paragraph 8. A method according to Paragraph 6 or Paragraph 7, wherein the starting frequency position is defined with respect to a starting frequency of the SBFD slot.

Paragraph 9. A method according to any of Paragraphs 6 to 8, wherein the starting frequency position is defined with respect to a starting frequency of the uplink subband.

Paragraph 10. A communications device, the communications device being a subband 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 random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, to determine that the slot containing the set of ROs is an SBFD slot, and to determine, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration. Paragraph 11. Circuitry for a communications device, the communications device being a subband 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 random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, to determine that the slot containing the set of ROs is an SBFD slot, and to determine, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration. Paragraph 12. 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 subband full duplex, SBFD, capable communications device, the method comprising transmitting, to the communications device, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, determining that the slot containing the set of ROs is an SBFD slot, and determining, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration. Paragraph 13. A method according to Paragraph 12, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently comprises performing a scaling operation on a configured value of the first parameter to define a smaller number of ROs in the set of ROs than configured by the PRACH configuration. Paragraph 14. A method according to Paragraph 13, wherein the scaling operation comprises scaling the configured value of the first parameter by an amount dependent on a ratio of a bandwidth of an uplink subband of the SBFD slot to a bandwidth of a non-SBFD uplink slot.

Paragraph 15. A method according to Paragraph 13 or Paragraph 14, wherein the scaling operation is performed based on the infrastructure equipment determining that there is not sufficient space in an uplink subband of the SBFD slot for all of the set of ROs configured by the PRACH configuration. Paragraph 16. A method according to any of Paragraphs 13 to 15, wherein the scaling operation comprises scaling the configured value of the first parameter by an amount dependent on a maximum number of the set of ROs that can fit in an uplink subband of the SBFD slot.

Paragraph 17. A method according to any of Paragraphs 12 to 16, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently comprises determining that the second parameter defines a starting frequency position within an uplink subband of the SBFD slot that enables all of the set of ROs to fit into the uplink subband.

Paragraph 18. A method according to Paragraph 17, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently further comprises performing, prior to determining that the second parameter defines the starting frequency position if there is not sufficient space in the uplink subband for all of the set of ROs configured by the PRACH configuration, a scaling operation on a configured value of the first parameter to define a smaller number of ROs in the set of ROs than configured by the PRACH configuration.

Paragraph 19. A method according to Paragraph 17 or Paragraph 18, wherein the starting frequency position is defined with respect to a starting frequency of the SBFD slot.

Paragraph 20. A method according to any of Paragraphs 17 to 19, wherein the starting frequency position is defined with respect to a starting frequency of the uplink subband.

Paragraph 21. 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 subband full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, to determine that the slot containing the set of ROs is an SBFD slot, and determine, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration. Paragraph 22. 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 subband full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, to determine that the slot containing the set of ROs is an SBFD slot, and to determine, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration. Paragraph 23. A wireless communications system comprising a communications device according to Paragraph 10 and an infrastructure equipment according to Paragraph 21.

Paragraph 24. 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 9 or Paragraphs 12 to 20.

Paragraph 25. A non-transitory computer-readable storage medium storing a computer program according to Paragraph 24.

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: Subband full duplex (SBFD),” CMCC, RAN# 102, December 2023.

[6] European Patent No. 3545716.

[7] TS 38.211 “Physical channels and modulation (Rel-18),” 3GPP, vl8.0.0, September 2023.

[8] TS 38.213, “Physical layer procedures for control (Rel-18),” 3GPP, vl8.0.0, September 2023.

[9] European patent application number EP24155834.5.

[10] Rl-2404616, “Discussion on SBFD random access operation,” Xiaomi, RAN1#117, May 2024.

[11] Rl-2404008, “Discussion on SBFD random access operation,” ZTE, RAN1#117, May 2024.

[12] Rl-2404318, “Random access in SBFD symbols,” Sharp, RAN1#117, May 2024.

[13] Rl-2403912, “SBFD random access operation,” Ericsson, RAN1#117, May 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 subband full duplex, SBFD, capable communications device, the method comprising receiving, from the infrastructure equipment, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, determining that the slot containing the set of ROs is an SBFD slot, and determining, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration.

2. A method according to Claim 1, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently comprises performing a scaling operation on a configured value of the first parameter to define a smaller number of ROs in the set of ROs than configured by the PRACH configuration.

3. A method according to Claim 2, wherein the scaling operation comprises scaling the configured value of the first parameter by an amount dependent on a ratio of a bandwidth of an uplink subband of the SBFD slot to a bandwidth of a non-SBFD uplink slot.

4. A method according to Claim 2, wherein the scaling operation is performed based on the communications device determining that there is not sufficient space in an uplink subband of the SBFD slot for all of the set of ROs configured by the PRACH configuration.

5. A method according to Claim 2, wherein the scaling operation comprises scaling the configured value of the first parameter by an amount dependent on a maximum number of the set of ROs that can fit in an uplink subband of the SBFD slot.

6. A method according to Claim 1, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently comprises determining that the second parameter defines a starting frequency position within an uplink subband of the SBFD slot that enables all of the set of ROs to fit into the uplink subband.

7. A method according to Claim 6, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently further comprises performing, prior to determining that the second parameter defines the starting frequency position if there is not sufficient space in the uplink subband for all of the set of ROs configured by the PRACH configuration, a scaling operation on a configured value of the first parameter to define a smaller number of ROs in the set of ROs than configured by the PRACH configuration.

8. A method according to Claim 6, wherein the starting frequency position is defined with respect to a starting frequency of the SBFD slot.

9. A method according to Claim 6. wherein the starting frequency position is defined with respect to a starting frequency of the uplink subband.

10. A communications device, the communications device being a subband 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 random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, to determine that the slot containing the set of ROs is an SBFD slot, and to determine, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration.

11. Circuitry for a communications device, the communications device being a subband 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 random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, to determine that the slot containing the set of ROs is an SBFD slot, and to determine, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration.

12. 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 subband full duplex, SBFD, capable communications device, the method comprising transmitting, to the communications device, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, determining that the slot containing the set of ROs is an SBFD slot, and determining, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration.

13. A method according to Claim 12, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently comprises performing a scaling operation on a configured value of the first parameter to define a smaller number of ROs in the set of ROs than configured by the PRACH configuration.

14. A method according to Claim 13, wherein the scaling operation comprises scaling the configured value of the first parameter by an amount dependent on a ratio of a bandwidth of an uplink subband of the SBFD slot to a bandwidth of a non-SBFD uplink slot.

15. A method according to Claim 13, wherein the scaling operation is performed based on the infrastructure equipment determining that there is not sufficient space in an uplink subband of the SBFD slot for all of the set of ROs configured by the PRACH configuration.

16. A method according to Claim 13, wherein the scaling operation comprises scaling the configured value of the first parameter by an amount dependent on a maximum number of the set of ROs that can fit in an uplink subband of the SBFD slot.

17. A method according to Claim 12, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently comprises determining that the second parameter defines a starting frequency position within an uplink subband of the SBFD slot that enables all of the set of ROs to fit into the uplink subband.

18. A method according to Claim 17, wherein determining that at least one of the first parameter and the second parameter is to be interpreted differently further comprises performing, prior to determining that the second parameter defines the starting frequency position if there is not sufficient space in the uplink subband for all of the set of ROs configured by the PRACH configuration, a scaling operation on a configured value of the first parameter to define a smaller number of ROs in the set of ROs than configured by the PRACH configuration.

19. A method according to Claim 17, wherein the starting frequency position is defined with respect to a starting frequency of the SBFD slot.

20. A method according to Claim 17, wherein the starting frequency position is defined with respect to a starting frequency of the uplink subband.

21. 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 subband full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, to determine that the slot containing the set of ROs is an SBFD slot, and to determine, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration.

22. 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 subband full duplex, SBFD, capable communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device, a physical random access channel, PRACH, configuration indicating a set of one or more PRACH, occasions, ROs, within a slot of the radio access interface and in which the communications device is able to transmit PRACH preambles to the infrastructure equipment, wherein the PRACH configuration indicates a first parameter that defines a number of the ROs in the set of ROs and a second parameter that defines a location of the set of ROs within the slot, to determine that the slot containing the set of ROs is an SBFD slot, and to determine, based on determining that the slot containing the set of ROs is an SBFD slot, that at least one of the first parameter and the second parameter is to be interpreted differently compared to how the at least one of the first parameter and the second parameter is indicated by the PRACH configuration.

23. A wireless communications system comprising a communications device according to Claim 10 and an infrastructure equipment according to Claim 21.

24. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to Claim 1 or Claim 12.

25. A non-transitory computer-readable storage medium storing a computer program according to Claim 24.