Methods, communications devices and infrastructure equipment for subband full duplex random access

Abstract

A method of operating a subband full duplex, SBFD, communications device is provided. The method comprises determining one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams. Determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface. The one or more validity conditions comprise a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface. The determining at least one of the mappings further comprises associating each of the SSBs with a preconfigured number of the valid ROs.

Description

[0001] METHODS, COMMUNICATIONS DEVICES AND INFRASTRUCTURE EQUIPMENT FOR SUBBAND FULL DUPLEX RANDOM ACCESS

[0002] BACKGROUND

[0003] Field of Disclosure

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

[0005] The present application claims Paris convention priority from EP patent application number 24155834.5, filed on 5 February 2024, the contents of which are hereby incorporated by reference in their entirety.

[0006] Description of Related Art

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

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

[0009] Current and future wireless communications networks are expected to routinely and efficiently support communications with an ever- in creasing 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 consideration may apply for efficiently supporting data exchange with a smartphone when it is running a video streaming application (high downlink data) as compared to when it is running an Internet browsing application (sporadic uplink and downlink data) or being used for voice communications by an emergency responder in an emergency scenario (data subject to stringent reliability and latency requirements).

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

[0011] 5G NR has continuously evolved and the current work plan includes 5G-NR-advanced in which some further enhancements are expected, especially to support new use- cases / scenarios with higher requirements. The desire to support these new use-cases and scenarios gives rise to new challenges for efficiently handling communications in wireless communications systems that need to be addressed.

[0012] SUMMARY OF THE DISCLOSURE

[0013] The present disclosure can help address or mitigate at least some of the issues discussed above.

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

[0015] It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the present technology. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

[0016] BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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:

[0018] 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;

[0019] 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;

[0020] 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;

[0021] Figure 4 schematically represents an example of non-overlapping subbands for uplink and downlink transmissions;

[0022] Figure 5 schematically represents an example of non-overlapping subbands for uplink and downlink transmissions;

[0023] Figure 6 schematically illustrates the components of an SSB; Figure 7 schematically illustrates an SSB burst set transmitted on SSB beams;

[0024] Figure 8 schematically illustrates a PRACH Occasion configuration;

[0025] Figure 9 schematically illustrates valid and invalid ROs;

[0026] Figure 10 schematically illustrates an example of a TDD slot format configuration;

[0027] Figure 11 schematically illustrates an example of an SSB to RO mapping in an Association Period for a TDD slot format;

[0028] Figure 12 schematically illustrates an SBFD slot format;

[0029] Figure 13 schematically illustrates an SSB to RO mapping in an Association Period for an SBFD slot format;

[0030] Figure 14 schematically illustrates ambiguity in SSB to RO mapping between an SBFD UE and a non-SBFD UE;

[0031] Figure 15A schematically illustrates a method of operating a communications device in accordance with example embodiments;

[0032] Figure 15B schematically illustrates a method of operating infrastructure equipment of a wireless communications network in accordance with example embodiments;

[0033] Figure 16 schematically illustrates valid ROs in an UL subband of SBFD OFDM symbols in accordance with example embodiments;

[0034] Figure 17 schematically illustrates a valid RO that overlaps a UL subband of SBFD OFDM symbols and UL OFDM symbols in accordance with example embodiments;

[0035] Figure 18 schematically illustrates SBFD-RO association for ROs in OFDM symbols in accordance with example embodiments;

[0036] Figure 19 schematically illustrates separate SSB-RO associations in accordance with example embodiments;

[0037] Figure 20 schematically illustrates separate PRACH configurations for SBFD and TDD in accordance with example embodiments;

[0038] Figure 21 schematically illustrates an SSB-RO mapping for non-SBFD, SBFD and TDD PRACH configurations in accordance with example embodiments.

[0039] Long Term Evolution Advanced Radio Access Technology (4G)

[0040] 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.

[0041] 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.

[0042] Data is transmitted from base stations 1 to communications devices 4 within their respective coverage areas 3 via a radio downlink. Data is transmitted from communications devices 4 to the base stations 1 via a radio uplink. The core network 2 routes data to and from the communications devices 4 via the respective base stations 1 and provides functions such as authentication, mobility management, charging and so on. Terminal devices may also be referred to as mobile stations, user equipment (UE), user terminal, mobile radio, communications device, and so forth. Services provided by the core network 2 may include connectivity to the internet or to external telephony services. The core network 2 may further track the location of the communications devices 4 so that it can efficiently contact (i.e. page) the communications devices 4 for transmitting downlink data towards the communications devices 4.

[0043] 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 embodiments is not intended to indicate these embodiments are limited to a certain generation of network that may be most associated with that particular terminology.

[0044] New Radio Access Technology (5G)

[0045] 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],

[0046] 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 (lloT) in order to support services with new requirements of high availability, high reliability, low latency, and in some cases, high-accuracy positioning.

[0047] 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 60.

[0048] 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.

[0049] 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.

[0050] 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 I 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.

[0051] 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.

[0052] 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 embodiment 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 I 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 embodiment at hand. For example, in some scenarios the network infrastructure equipment I 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] The interface 46 between the DU 42 and the CU 40 is known as the F1 interface which can be a physical or a logical interface. The F1 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 F1 interface 46 from the DU 42 to the CU 40.

[0057] 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 utilizing sub-THz frequencies.

[0058] Full Duplex Time Division Duplex (FD-TDD)

[0059] 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],

[0060] 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 a UL transmission from a second UE within the same orthogonal frequency division multiplexing (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.

[0061] 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-utilized. However, if resources can be used for DL data and UL data (as in FD-TDD) at the same time, the resource utilization 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), 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.

[0062] In 3GPP Rel-19 Duplex Evolution, FD-TDD is performed at a 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.

[0063] One of the objectives of the 3GPP Rel-19 Duplex Evolution is to support RACH operation in SBFD OFDM symbols.

[0064] Subband Full Duplex (SBFD)

[0065] In SBFD, the frequency resource of a TDD system bandwidth or Bandwidth Part (BWP) (i.e. at the UE / gNB) is divided into two or more non-overlapping sub-bands, where each sub-band can be DL or UL [5], Guard subbands may be used between DL and UL subbands to reduce inter subband interference.

[0066] An example is shown in Figure 4, where simultaneous DL and UL transmissions occur in different non-overlapping sub-bands 401 to 403, i.e. in different sets of frequency Resource Blocks (RB): Sub-band#1 401, Sub-band#2402, Sub-band#3403, such that Sub-band#1 401 and Sub-band#3 403 are used for DL transmissions whilst Sub-band#2 402 is used for UL transmissions.

[0067] While Figure 4 shows the system bandwidth as being divided into three sub-bands, any number of sub-bands could be used. For example, the system bandwidth may be divided into four sub-bands, which may include the two downlink sub-bands 401 , 403, the uplink sub-band 402 and another uplink subband, though other sub-band arrangements are envisioned. To reduce leakage from one sub-band 401 to 403 to another, a guard sub-band 410 may be configured between UL and DL sub-bands 401 to 403. Guard sub-bands 410 are configured between DL Sub-band#3 403 and UL Sub-band#2 402 and between UL Sub-band#2 402 and DL Sub-band#1 401.

[0068] The arrangement of sub-bands 401 to 403 shown in Figure 4 is just one possible arrangement of the sub-bands and other arrangements are possible, and guard bands may be used in substantially any sub-band arrangement.

[0069] Figure 5 shows two further examples with a DL and UL subband separated by a guard subband. For example, on the left-side of Figure 5, a UL subband#1 501 is separated from a DL subband#2 503 by a guard subband 502. In this case, the DL subband#2 503 occupies a higher frequency portion of the system bandwidth than the UL subband#1 501. On the rightside of Figure 5, a DL subband#1 504 is separated from a UL subband#2 506 by a guard subband 505. In this case, the UL subband#2 506 occupies a higher frequency portion of the system bandwidth than the DL subband#1 504.

[0070] Synchronisation Signal Block (SSB)

[0071] 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.

[0072] 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 4 OFDM symbols and 240 subcarriers. The PSS and SSS each occupy 127 subcarriers. The PBCH occupies two OFDM symbols of 240 subcarriers and also 2 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.

[0073] 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.

[0074] 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 8 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, 2 SSBs are configured per slot within 4 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).

[0075] 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.

[0076] 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 DM RS is transmitted.

[0077] 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 I 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.

[0078] PRACH Occasions

[0079] As will be understood by a person skilled in the art, a PRACH configuration comprises a plurality of PRACH Occasions (RO) configured in uplink communications resources of a wireless access interface. The ROs in a PRACH configuration may be periodically repeating. The ROs represent transmission opportunities for a UE to transmit a PRACH. Each RO may be configured to support up to 64 preambles. In this case, each RO may support a PRACH transmission of up to 64 UEs if each UE uses a different preamble for its PRACH transmission. The ROs may be Frequency Division Multiplexed (FDM) where infrastructure equipment of a wireless communications network can configure {1, 2, 4, 8} FDM ROs for UEs.

[0080] 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 & 6.3.3.2- 4 in [6], 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.

[0081] 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 [6]: The PRACH Configuration Period = 20 ms since an RO occurs in every even numbered SNF (x=2 & 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 7 sets of time domain ROs where each RO is 2 OFDM symbol long. Since FDM = 2, each time domain RO has 2 ROs, this gives 14 ROs in a PRACH slot as shown in Figure 8. There are therefore 28 ROs in a PRACH Configuration Period of 20 ms (2 PRACH slots in 20ms * 7 time domain ROs x 2 FDM = 28 ROs).

[0082] SSB to PRACH Occasion Association

[0083] 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.

[0084] 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, 14, 14, 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 2 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 less than 64 preambles.

[0085] Once the SSB parameters, RO parameters and SSB-RO association parameters are configured, the UE may then perform the following steps in sequential order:

[0086] 1. Valid ROs determination

[0087] 2. Indexing the valid ROs

[0088] 3. Perform SSB-RO mapping

[0089] Valid ROs Determination

[0090] For FDD all configured ROs are valid.

[0091] For TDD, the following 3 legacy validity conditions must be met for an RO to be valid:

[0092] First legacy validity condition: A valid RO is contained fully in UL OFDM symbols since PRACH cannot be transmitted in DL OFDM symbols.

[0093] Second legacy validity condition: In addition to being fully contained in UL OFDM symbols, there also needs to be a gap of NgapOFDM symbols between the end of an SSB and the start of the valid RO. The value of Ngapdepends on the subcarrier spacing of the PRACH and it is defined in [7], the contents of which are hereby incorporated by reference in their entirety. Third legacy validity condition: If an RO and an SSB falls within a PRACH slot, the RO is invalid if it precedes the SSB.

[0094] Examples of valid and invalid ROs are shown in Figure 9. The valid RO labelled as (A) in Figure 9 meets all the 3 validity conditions. The invalid ROs are labelled as (B) falling onto DL OFDM symbols, (C) insufficient gap between SSB and RO and (D) the RO precedes a SSB within a PRACH slot.

[0095] RO Indexing

[0096] Once the valid ROs are determined, they are indexed in the following order:

[0097] 1. First, in increasing order of preamble indexes within a single RO

[0098] 2. Second, in increasing order of frequency resource indexes for frequency multiplexed RO

[0099] 3. Third, in increasing order of time resource indexes for time multiplexed PRACH occasions within a PRACH slot

[0100] 4. Fourth, in increasing order of indexes for PRACH slots

[0101] SSB-RO Mapping

[0102] 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 [7], which is reproduced below as Table 1.

[0103] Table 1. PRACH Configuration Period and SSB-RO Association Period (from Table 8.1-1 of TS38.213)

[0104] 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 4 DL slots followed by an UL slot as shown in Figure 10 operating in 15 kHz subcarrier spacing. SSB and PRACH are configured as follows:

[0105] • SSB burst set has 5 SSBs {SSB#1 , SSB#2, SSB#3, SSB#4, SSB#5}

[0106] • SSB per RO = 1 , i.e., each SSB is mapped to 2 ROs

[0107] • Preambles per SSB = 64, i.e., all preambles in an RO are fully mapped to an SSB

[0108] • FDM RO = 2

[0109] • PRACH Configuration Index = 129 for FR1 TDD Using the lookup table in Table 6.3.3.2-3 of [6], the time resource configuration for PRACH Configuration Index = 129 has a PRACH Configuration Period = 10 ms, as shown in Figure 11. Here, in each PRACH Configuration Period, Subframe 3, 4, 8 and 9 contain PRACH slot, and in each PRACH slot, there are 2 time domain ROs with duration 6 OFDM symbols each, which leads to 16 ROs in a PRACH Configuration Period (4 PRACH slot x 2 time domain ROs per PRACH slot x 2 FDM ROs). Since valid RO can only reside in UL OFDM symbols, only subframe 4 and 9 have valid ROs and the ROs in subframe 3 and 8 are invalid ROs. Hence, each PRACH Configuration Period has 8 valid ROs.

[0110] For a PRACH Configuration Period = 10 ms, referring to Table (i.e. , from Table 8.1-1 of [7]), the required SSB-RO Association Period to fully map all 5 SSBs with SSB per RACH = 1 , is 2x 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 = 14, SSB#1 is mapped to RO#1 and RO#2, followed by SSB#2 is mapped to RO#3 and RO#4, etc. The 5 SSBs are fully mapped to the ROs once in the SSB-RO Association Period with 6 remaining ROs: RO#11 , RO#12, RO#13, RO#14, RO#15 and RO#16, that cannot fully map another set of 5 SSBs. Hence these 6 remaining ROs are Invalid ROs and are not used for PRACH transmissions.

[0111] As described previously, an objective of the Rel-19 Duplex Evolution is to support RACH operation in SBFD OFDM symbols, which would increase the RACH opportunities for UEs that support SBFD. In other words, ROs can be configured in a UL subband of SBFD OFDM symbols or SBFD slots in addition to existing ROs configured in UL slots for legacy UEs. Since the SSB-RO association is based on a number of valid ROs in an SSB-RO Association Period, the introduction of additional ROs in SBFD slots may cause ambiguity in the SSB-RO association.

[0112] An example of how such ambiguities arise will now be described with reference to Figures 11 to 14.

[0113] Figure 11 illustrates a legacy mapping between SSBs and ROs with a PRACH configuration index of 129. According to PRACH configuration index 129, ROs are located in subframes (i.e. PRACH slots) 3, 4, 8 and 9. The ROs in subframes 3 and 8 are invalid because these are downlink subframes. The first instance of subframe 4 in the SSB Association Period comprises ROs#1-RO#4, the first instance of subframe 9 in the SSB-RO Association Period comprises ROs#5-8, the second instance of subframe 4 in the SSB Association Period comprises ROs#9-RO#12, and the second instance of subframe 9 in the SSB-RO Association Period comprises ROs#13-16. As shown in Figure 11 , RO#1 and RO#2 are mapped to SSB#1, RO#3 and RO#4 are mapped to SSB#2, ROs#5 and RO#6 are mapped to SSB#3, RO#7 and RO#8 are mapped to SSB#4 and RO#9 and RO#10 are mapped to SSB#5. ROs#11-16 are invalid ROs because all of the SSBs in a burst set have already been mapped.

[0114] Figure 12 illustrates an SBFD slot format {XXXXU}, where X = SBFD slot, i.e., 4 SBFD slots followed by a UL slot. An example of a mapping between SSBs and ROs in the SBFD slot format of Figure 12 is shown in Figure 13. As shown in Figure 13, the PRACH configuration of the ROs has a PRACH configuration index of 129. SBFD slots are slots 0 to 3 and 5 to 8 in Figure 13. Although not shown in Figure 13, each of the ROs in SBFD slots are fully contained within the UL subbands of the SBFD slots. Assuming that ROs fully contained within UL subbands are considered valid ROs, this means that the SBFD slot format provides more valid ROs per PRACH Configuration Period compared to the legacy TDD slot format. For example, the SSB-RO Association Period for an SSB-RO mapping for the PRACH configuration in SBFD is 1x PRACH Configuration Period (10 ms), which gives 16 valid ROs per PRACH configuration period prior to SSB-RO Association, compared to 8 valid ROs in a legacy TDD format. After SSB-RO association, RO#11, RO#12, RO#13, RO#14, RO#15 and RO#16 are invalid ROs since they cannot fully map all the SSBs in an SSB burst set.

[0115] Since legacy UEs and SBFD UEs may use the same set of ROs but have different valid ROs, this leads to different SSB to RO mappings, which causes ambiguity at the gNB as to which SSB is selected by the UE for a PRACH transmitted in ROs located in an UL slot. For example, Figure 14 shows an SSB to RO mapping in an SBFD slot format and a legacy TDD slot format for the PRACH configuration with PRACH Configuration Index = 129. For the SBFD slots comprising ROs (i.e. slots 3 and 8), the ROs are assumed to be completely contained within the UL subbands of the SBFD slots in the example of Figure 14. In Figure 14, two PRACH Configuration Periods (20 ms) containing a total of 32 ROs are shown. For SBFD, the SSB- RO mapping is for 2 Association Periods (2 x 1 PRACH Configuration Period) whilst for TDD, the SSB-RO mapping is for 1 Association Period (1 x 2 PRACH Configuration Period). Since legacy UEs do not understand or not aware of SBFD slots, these SBFD slots are treated by the legacy UE as DL slots as per the legacy TDD slot format configuration. In other words, legacy UEs consider ROs in the SBFD slots as being invalid ROs. Therefore, for legacy UEs, there are only 16 valid ROs in 20 ms period (prior to SSB-RO association), as PRACH slots in subframe 3 and 8 fall into SBFD slots and are therefore invalid. However, for SBFD, ROs in all PRACH slots are valid (prior to SSB-RO association) and therefore they have 32 valid ROs in the 20 ms period. Consequently, the SSB-RO mappings are different for SBFD UEs and legacy UEs. If a PRACH is in any of ROs#1-6 in subframe 4 of SEN k as shown in Figure 14, the gNB would not be able to determine whether the UE has selected SSB#3 (if it is a SBFD UE) or SSB#1 (if it is a legacy UE).

[0116] There is therefore a need for improved method, communications devices and infrastructure equipment to resolve ambiguities in SSB to RO mappings.

[0117] Figure 15A is a flow diagram illustrating a method of operating a subband full duplex, SBFD, communications device in accordance with example embodiments.

[0118] An SBFD communications device is a communications device which is capable using an SBFD slot format. A non-SBFD communications device is a communications device which is not capable of using an SBFD slot format. A non-SBFD communications device may alternatively be referred to as a legacy communications device.

[0119] An example of a communications device is a UE. An example of infrastructure equipment of the wireless communications network is a gNB.

[0120] The method starts in step S1.

[0121] The method comprises determining one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams.

[0122] In some embodiments, the communications device may receive an indication of a PRACH configuration from the infrastructure equipment. The PRACH configuration comprises the plurality of ROs configured in the communications resources of the wireless access interface.

[0123] As shown in step S2, determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface. The one or more validity conditions comprise a first validity condition or a second validity condition.

[0124] The first validity condition is a condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface.

[0125] As will be understood by a person skilled in the art, an uplink, or UL, OFDM symbol is an OFDM symbol comprised of communications resources which are reserved for uplink transmissions.

[0126] The second validity condition is a condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

[0127] As will be understood by a person skilled in the art, an SBFD OFDM symbol is an OFDM symbol comprised of uplink communications resources reserved for uplink transmissions and downlink communications resources reserved for downlink transmissions. The uplink subband of an SBFD OFDM symbols refers to a range of frequencies in the SBFD OFDM symbol which consist of uplink communications resources. For example, an SBFD symbol may comprise frequency resources between f1 and f4. Downlink communications resources may be between f1 and f2, and between f3 and f4, in the SBFD OFDM symbol and uplink communications resources may be between f2 and f3 in the SBFD OFDM symbol. In this case, the range f2 to f3 refers to the uplink subband of the SBFD OFDM symbol.

[0128] In some embodiments, the determining one or more mappings between the plurality of ROs and the plurality of SSBs comprises determining a first and second mapping, wherein the determined at least one mapping is the first mapping. The determining the second mapping comprises determining valid ROs for the second mapping by applying one or more validity conditions for the second mapping to the plurality of ROs configured in the communications resources of the wireless access interface, and associating each of the SSBs with the preconfigured number of the valid ROs for the second mapping.

[0129] In some embodiments, the validity conditions for the first mapping comprise the first validity condition and the validity conditions for the second mapping comprise the second condition, or the validity conditions for the first mapping comprise the second condition and the validity conditions for the second mapping comprise the first validity condition. In some embodiments, the validity conditions for the first mapping comprise the first validity condition, the first mapping is determined before the second mapping, and the second mapping comprises a third validity condition that valid ROs must not have already been mapped according to the first mapping. In other embodiments the validity conditions for the second mapping comprise the first validity condition, the second mapping is determined before the first mapping, and the first mapping comprises a third validity condition that that valid ROs must not have already been mapped according to the second mapping.

[0130] In some embodiments, the validity conditions for the first mapping comprise the third validity condition and the validity conditions for the first mapping comprise the second validity condition, or the validity conditions for the second mapping comprise the third validity condition and the validity conditions for the second mapping comprise the second validity condition.

[0131] In some embodiments, the validity conditions for the first mapping comprise the third validity condition and the validity conditions for the first mapping comprise a fourth validity condition, or the validity conditions for the second mapping comprise the third validity condition and the validity conditions for the second mapping comprise the fourth validity condition. The fourth validity condition is a condition that valid ROs must be completely contained either within uplink OFDM symbols in the communications resources of the wireless access interface or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

[0132] In some embodiments, the validity conditions for the first mapping comprise the third validity condition and the validity conditions for the first mapping comprise a fifth validity condition, or the validity conditions for the second mapping comprise the third validity condition and the validity conditions for the second mapping comprise the fifth validity condition. The fifth validity condition is a condition that valid ROs must be completely contained within uplink OFDM symbols in the communications resources of the wireless access interface, or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or a part of a valid RO is contained in uplink OFDM symbols in the communications resources of the wireless access interface and the other part of the valid RO is contained in an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

[0133] In some embodiments, the one or more validity conditions may additionally comprise a gap condition that an RO is invalid if there is less than a predefined number (Ngap) of OFDM symbols between any one of the SSBs and the start of the RO. In some embodiments, the one or more validity conditions may additionally comprise a slot condition that an RO is invalid if the RO is in the same slot as any one of the SSBs and the RO precedes the SSB in the slot. In other words, if an SSB and RO are in the same slot, the RO is can only be valid if it occurs after the SSB in the slot.

[0134] In some embodiments, the communications device applies the first validity condition, the gap condition and the slot condition. In some embodiments, the communications device applies the second validity condition, the gap condition and the slot condition. In some embodiments, the infrastructure equipment may transmit an indication to the communications device to determine a plurality of mappings between the plurality of ROs and the plurality of SSBs. The indication to determine the plurality of mappings may comprise, for each mapping, an indication of one or more validity conditions to apply to the plurality of ROs to determine the mapping. The one or more validity conditions for at least one of the mappings may comprise the first or fourth validity condition. The one or more validity conditions for a different one of the mapping may comprise the other of the first and fourth validity condition, or the one or more validity conditions for the different one of the mapping may comprise the third validity condition, for example.

[0135] As shown in step S3, the determining at least one of the mappings further comprises associating each of the SSBs with a preconfigured number of the valid ROs.

[0136] The preconfigured number may be an integer greater than one, in which case more than one valid RO is associated with each SSB. The preconfigured number may be a fraction, in which case more than one SSB is associated with each valid RO.

[0137] In some embodiments, the communications device may receive an indication of the preconfigured number of valid ROs from the infrastructure equipment. For example, the communications device may receive an indication of a preconfigured number of SSBs to associate with each RO. The indication may be transmitted to the communications device in the following RRC parameter from the infrastructure equipment: ssb-perRACH- OccasionAndCB-PreamblesPerSSB.

[0138] In some embodiments, the associating each of the SSBs with a preconfigured number of the valid ROs comprises firstly, indexing the valid ROs, and, secondly, associating the SSBs to the indexed ROs sequentially by RO index. The association may be repeated every “SSB-RO Association Period” which 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.

[0139] The indexing of the valid ROs may comprise indexing the valid ROs in the following order:

[0140] 1. First, in increasing order of preamble indexes within a single RO,

[0141] 2. Second, in increasing order of frequency resource indexes for a frequency multiplexed RO,

[0142] 3. Third, in increasing order of time resource indexes for time multiplexed PRACH occasions within a PRACH slot,

[0143] 4. Fourth, in increasing order of indexes for PRACH slots.

[0144] PRACH slots are slots which comprise one or more ROs.

[0145] In some embodiments, the method comprises receiving one or more of the SSBs from the infrastructure equipment. For example, the infrastructure equipment may transmit a plurality of the SSBs on a plurality of respective beams in a burst set. In some embodiments, the method comprises selecting one of the SSBs received from the infrastructure equipment. For example, the communications device may measure a signal quality (e.g. an RSRP and / or an RSRQ) of the received SSBs and select the SSB with the highest signal quality (e.g. the SSB with the highest RSRP and / or RSRQ).

[0146] In some embodiments, the method comprises selecting one of the plurality of ROs for transmitting a PRACH to the infrastructure equipment. The selected RO is an RO associated with the selected the SSB according to the determined at least one mapping. If there are multiple ROs associated with the selected SSB according to the determined at least one mapping, the SBFD communications device may randomly select one of the associated ROs.

[0147] In some embodiments, the method comprises transmitting a PRACH to the infrastructure equipment in the selected RO. The infrastructure equipment may determine which of the plurality of SSBs the communications device selected based on the RO in which the PRACH is received because the infrastructure equipment is aware of the determined at least one mapping. Therefore, the infrastructure equipment may use the downlink beam on which the selected SSB was transmitted for subsequent transmissions to the communications device, such as Msg3 in a RACH process.

[0148] The method ends in step S4.

[0149] By applying the first validity condition, the SBFD communications device and a legacy communications device will determine the same ROs in a given PRACH configuration as being valid. By applying the second validity condition, the SBFD communications device and a legacy communications device will not have any valid ROs in common in a given PRACH configuration. In either case, no ambiguity will arise at the infrastructure equipment as to which SSB a particular RO is mapped to. Accordingly, the method of operating an SBFD communications device as described with reference to Figure 15A can improve communications efficiency.

[0150] Figure 15B is a flow diagram illustrating a method of operating infrastructure equipment of a wireless communications network in accordance with example embodiments.

[0151] The method starts in step S11.

[0152] In step S12, the method comprises transmitting an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device.

[0153] The first PRACH configuration comprises a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment.

[0154] In step S13, the method comprises transmitting an indication of a second PRACH configuration to a non-SBFD communications device. The second PRACH configuration comprises a plurality of ROs configured for the non-SBFD communications device in the communications resources of the wireless access interface.

[0155] The first PRACH configuration and the second PRACH configuration are different. For example, the first and second PRACH configurations may comprise one or more nonoverlapping ROs or, if the ROs between the first and second PRACH configuration overlap, the overlapping ROs may use different preambles.

[0156] In some embodiments, one or more of the ROs in the first PRACH configuration and one or more of the ROs in the second PRACH configuration are completely contained within uplink OFDM symbols in the communications resources of the wireless access interface, and the ROs in the first PRACH configuration which are completely contained within uplink OFDM symbols do not overlap with the ROs in the second PRACH configuration which are completely contained within uplink OFDM symbols.

[0157] Non-overlapping ROs do not share communications resources in the wireless access interface. In other words, non-overlapping ROs do not share time and frequency resources but may share time resources if they do not share frequency resources or share frequency resources if they do not share time resources.

[0158] In some embodiments, the method comprises transmitting a plurality of synchronisation signal blocks (SSBs) on a plurality of downlink beams. For example, the infrastructure equipment may transmit a plurality of the SSBs on a plurality of respective beams in a burst set.

[0159] In some embodiments, the method comprises receiving a PRACH from the SBFD communications device in one of the ROs in the first PRACH configuration and / or receiving a PRACH from the non-SBFD communications device in one of the ROs in the second PRACH configuration.

[0160] The method ends in step S14.

[0161] Since the first and second PRACH configurations are different, no ambiguity arises at the infrastructure equipment as to which SSB a communications device has selected because there are ROs (or RO preambles) that are different between different PRACH configurations.

[0162] As will be appreciated by one skilled in the art, the order of steps S12 and S13 may be interchanged.

[0163] Valid ROs determination

[0164] As mentioned previously, legacy UEs in TDD determine valid ROs by applying a legacy valid RO determination method which involves applying the following three legacy validity conditions, namely:

[0165] First legacy validity condition: A valid RO is contained fully in UL OFDM symbols since PRACH cannot be transmitted in DL OFDM symbols.

[0166] Second legacy validity condition: In addition to being fully contained in UL OFDM symbols, there also needs to be a gap of NgapOFDM symbols between the end of an SSB and the start of the valid RO. The value of Ngapdepends on the subcarrier spacing of the PRACH and it is defined in [7], the contents of which are hereby incorporated by reference in their entirety.

[0167] Third legacy validity condition: If an RO and an SSB falls within a PRACH slot, the RO is invalid if it precedes the SSB.

[0168] In accordance with example embodiments, SBFD UEs may be configured to apply a first valid RO determination method comprising applying one or more validity conditions to ROs. In the first valid RO determination method, a validity condition is that valid ROs must be completely contained within uplink OFDM symbols (referred to as the “first validity condition” throughout this disclosure). The first validity condition is therefore the same as the first legacy validity condition currently used by legacy (i.e. non-SBFD) UEs. Therefore, ROs that partially or fully overlap SBFD OFDM symbols are invalid ROs. The first valid RO determination method may also comprise applying the second and third legacy validity conditions mentioned above. Implementing the first valid determination method means that SBFD UEs will determine that the same ROs are valid as compared to legacy UEs, thereby resolving the ambiguity at the gNB.

[0169] In accordance with example embodiments, SBFD UEs may be configured to apply a second valid RO determination method comprising applying one or more validity conditions to ROs. In the second valid determination method, a validity condition is that valid ROs must be completely contained either within uplink OFDM symbols or within an uplink subband of SBFD OFDM symbols (referred to as the “fourth validity condition” throughout this disclosure). The second valid RO determination method may also comprise applying the second and third legacy validity conditions mentioned above.

[0170] An example of an application of the second RO valid determination method is illustrated in Figure 16. As shown in Figure 16, RO#n, RO#n+2, RO#n+4 and RO#n+6 are fully contained in the UL subband of SBFD OFDM symbols, and are therefore valid ROs. The first OFDM symbol of RO#n+8 is fully in the UL subband but the second OFDM symbol of RO#n+8 is in a DL OFDM symbol. Therefore, RO#n+8 is an invalid RO. The remaining OFDM symbols are outside of the UL subband and so they are invalid ROs.

[0171] In accordance with example embodiments, SBFD UEs may be configured to apply a third valid RO determination method comprising applying one or more validity conditions to ROs. In the third valid determination method, a validity condition is that valid ROs must be completely contained within uplink OFDM symbols, or completely contained within an uplink subband of SBFD OFDM symbols, or a part of a valid RO is contained in uplink OFDM symbols and the other part of the valid RO is contained in an uplink subband of SBFD OFDM symbols (referred to throughout this disclosure as the “fifth validity condition”). In other words, if an RO is comprised exclusively of uplink resource elements, then the RO is valid irrespective of whether the uplink resource elements belong to uplink OFDM symbols or an uplink subband of SBFD OFDM symbols. The third valid RO determination method may also comprise applying the second and third legacy validity conditions mentioned above.

[0172] An example of an application of the third valid RO determination method is illustrated in Figure 17. As shown in Figure 17, a part of RO#n+2 in the UL subband of SBFD OFDM symbols and the other part of RO#n+2 is in UL OFDM symbols. Consequently, RO#n+2 is a valid RO according to the third valid RO determination method. Furthermore, since RO#n is completely contained within the UL subband of SBFD OFDM symbols, RO#n is also a valid RO. RO#n+1 and RO#n+3 are invalid ROs because they do not satisfy the “fifth validity condition”.

[0173] In accordance with example embodiments, SBFD UEs may be configured to apply a fourth valid RO determination method comprising applying one or more validity conditions to ROs. In the fourth valid RO determination method, a validity condition is that valid ROs must be completely contained in an uplink subband of SBFD OFDM symbols (referred to as the “second validity condition” throughout this disclosure). Therefore, ROs that partially or fully overlap uplink OFDM symbols are invalid ROs. The fourth valid RO determination method may also comprise applying the second and third legacy validity conditions mentioned above.

[0174] In accordance with example embodiments, SBFD UEs may be configured to apply a fifth valid RO determination method comprising applying one or more validity conditions to ROs. In the fifth valid determination method, a validity condition is that previously mapped ROs are invalid (referred to as the “third validity condition” throughout this disclosure). In other words, any RO that has already been mapped to an SSB in previous SSB-RO association are considered invalid ROs. Then, either the legacy, first, second, third or fourth valid RO determination method is applied to the remaining ROs to determine valid ROs among the remaining ROs.

[0175] Multiple SSB-RO Mappings for one PRACH Configuration

[0176] In accordance with example embodiments, an SBFD UE may be configured to determine a plurality of SSB to RO mappings for a given PRACH configuration.

[0177] In some embodiments, one of the plurality of mappings is for non-SBFD symbols and a different one of the plurality of mappings is for SBFD OFDM symbols. For example, the mapping for the non-SBFD OFDM symbols may use the first valid RO determination method. Accordingly, in the mapping for the non-SBFD OFDM symbols, ROs which overlap SBFD OFDM symbols are invalid.

[0178] In some embodiments, the mapping for the SBFD OFDM symbols uses the fourth valid RO determination method. Accordingly, in the mapping for the SBFD OFDM symbols, ROs which overlap with uplink OFDM symbols are invalid while ROs which are completely contained within a UL subband of SBFD OFDM symbols are valid.

[0179] An example of a mapping for SBFD OFDM symbols which uses the fourth valid RO determination method is illustrated in Figure 18. As shown in Figure 18, the PRACH configuration index is 129. Furthermore, in the example shown in Figure 8, it is assumed that the ROs in the SBFD slots (i.e slots 0 to 3 and 5 to 8) are completely contained within a UL subband of SBFD symbols in those slots.

[0180] According to the fourth valid RO determination method, ROs in SBFD OFDM symbols considered as valid ROs whilst those in UL OFDM symbols are invalid ROs,. Therefore, in Figure 18, the valid ROs are in subframes 3 and 8, and the invalid ROs are in subframes 4 and 9, which gives 16 valid ROs per PRACH Configuration Period. The SSB-RO Association Period is therefore 2x PRACH Configuration Period. The resultant SBFD SSB to RO mapping is shown in Figure 18. As shown in Figure 18, SSB#1 is mapped to RO#1 and RO#2, SSB#2 is mapped to RO#3 and RO#4, SSB#3 is mapped to RO#5 and RO#6, SSB#4 is mapped to RO#7 and RO#8, and SSB#5 is mapped to RO#9 and RO#10. ROs#11 to RO#16 are invalid.

[0181] Figure 19 schematically illustrates an example of an SBFD UE being configured with one mapping for non-SBFD symbols which uses the first valid RO determination method (labelled “Non-SBFD”) and another mapping for SBFD symbols which uses the fourth valid RO determination method (labelled “SBFD”). As will be appreciated from Figure 19, there is no ambiguity in the SSB to RO mapping because each RO is uniquely mapped to an SSB in contrast to the situation illustrated in Figure 14. Therefore, if a UE transmits a PRACH using the RO#1 in Subframe 4 of SFN k, which is an UL slot, the gNB knows that the UE has selected SSB#1.

[0182] It will be appreciated from Figure 19 that, in the 20 ms SSB-RO Association Period shown in Figure 19, an SBFD UE can use all 64 ROs whilst a legacy UE can only use the 32 ROs located in UL slots. In other words, the legacy UE uses only the ROs from the non-SBFD mapping. Since the SBFD UE is configured with both the mapping for the non-SBFD OFDM symbols and the mapping for the SBFD OFDM symbols, the SBFD UE can select an RO in SBFD slots (e.g., Subframe 3 and Subframe 8) as well as in UL slots (e.g., Subframe 4 and Subframe 9).

[0183] As shown in Figure 19, the SBFD mapping is: SSB#1 is mapped to RO#1 and RO#2 in subframe 3 of SFN k, SSB#2 is mapped to RO#3 and RO#4 in subframe 3 of SFN k, SSB#3 is mapped to RO#5 and RO#6 in subframe 8 of SFN k, SSB#4 is mapped to RO#7 and RO#8 in subframe 8 of SFN k, and SSB#5 is mapped to RO#9 and RO#10 in subframe 3 of SFN k+1.

[0184] As shown in Figure 19, the non-SBFD mapping is: SSB#1 is mapped to RO#1 and RO#2 in subframe 4 of SFN k, SSB#2 is mapped to RO#3 and RO#4 in subframe 4 of SFN k, SSB#3 is mapped to RO#5 and RO#6 in subframe 9 of SFN k, SSB#4 is mapped to RO#7 and RO#8 in subframe 9 of SFN k, and SSB#5 is mapped to RO#9 and RO#10 in subframe 4 of SFN k+1.

[0185] In some embodiments, the mapping for the non-SBFD OFDM symbols uses the first valid RO determination method and the mapping for the SBFD OFDM symbols uses the fifth valid RO determination method. For example, the first valid determination method is applied first such that only ROs completely contained within uplink OFDM symbols are valid ROs in the mapping for the non-SBFD OFDM symbols. Then, in the mapping for the SBFD OFDM symbols, the fifth valid determination method is applied such that the ROs in the PRACH configuration which have already been mapped according to the mapping for the non-SBFD OFDM symbols are considered invalid ROs in the mapping for the SBFD OFDM symbols. The second, third or fourth valid RO determination may be applied to the ROs which have not been already mapped according to the mapping for the non-SBFD OFDM symbols in order to arrive at the mapping for the SBFD OFDM symbols. Since such embodiments ensure that different mappings use different ROs, there will be no ambiguity at the gNB.

[0186] Using the same PRACH Configuration as in the example in Figure 19, such embodiments will produce the same combined SSB-RO mapping as shown in Figure 19. Additional SBFD PRACH Configurations

[0187] Single Separate PRACH Configuration

[0188] In accordance with example embodiments, an SBFD UE may be configured with a PRACH configuration (referred to as an “SBFD PRACH configuration”) that is different from the legacy PRACH configuration. The SBFD UE therefore uses the ROs provided by the SBFD PRACH configuration for PRACH transmission. In some embodiments, the ROs in the SBFD PRACH configuration may overlap with ROs in legacy PRACH configuration. For configurations where the ROs of the SBFD PRACH configuration and the legacy PRACH configuration overlap, the gNB may differentiate the ROs in the SBFD PRACH configuration from the ROs in the legacy PRACH configuration by using different preambles for the ROs in the SBFD PRACH configuration compared with the ROs in the legacy PRACH configuration.

[0189] In some embodiments, the SBFD UE may apply an SSB to RO mapping to the ROs in the SBFD PRACH configuration which uses the second or third valid RO determination method. Since the ROs in the SBFD PRACH configuration and legacy PRACH configuration do not overlap, there is no ambiguity in the UE selected SSB at the gNB. As an example, consider an FR1 TDD system with 5 SSBs {SSB#1, SSB#2, SSB#3, SSB#4, SSB#5} and with two PRACH configurations, one for legacy TDD (a “legacy PRACH Configuration”) and another for SBFD (“an SBFD PRACH configuration”), as shown in Table 2.

[0190] Table 2: PRACH Configurations for Legacy TDD and SBFD

[0191] The ROs for the legacy and SBFD PRACH configurations do not overlap as they occupy different frequency resources, i.e., ROs in the SBFD PRACH configuration occupy whilst ROs in the legacy PRACH configuration occupy & f3. The number of valid ROs prior to SSB- RO association, for each PRACH configuration is:

[0192] • For the legacy PRACH configuration with PRACH Configuration Index = 127, each PRACH Configuration Period of 10 ms contains 2 PRACH slots in Subframes 4 and 9 (which are UL slots), where in each PRACH slot, there are 2 time domain ROs, and with FDM = 2, gives 8 valid ROs per PRACH Configuration Period.

[0193] • For the SBFD PRACH configuration with PRACH Configuration Index = 129, each PRACH Configuration Period of 10 ms contains 4 PRACH slots in Subframes 3, 4, 8 and 9, where in each PRACH slot, there are 2 time domain ROs, and with FDM = 1 , gives 8 valid ROs per PRACH Configuration Period.

[0194] The SSB-RO Association Periods for both the legacy and SBFD PRACH configurations is 20 ms. The resultant SSB-RO mappings for the legacy and SBFD PRACH configurations is shown in Figure 20. As shown in Figure 20, each RO is uniquely mapped to a SSB and hence this avoids any ambiguity at the gNB in determining the SSB selected by a UE.

[0195] As shown in Figure 20, the legacy TDD mapping is: SSB#1 is mapped to RO#1 and RO#2 in subframe 4 of SFN k, SSB#2 is mapped to RO#3 and RO#4 in subframe 4 of SFN k, SSB#3 is mapped to RO#5 and RO#6 in subframe 9 of SFN k, SSB#4 is mapped to RO#7 and RO#8 in subframe 9 of SFN k, and SSB#5 is mapped to RO#9 and RO#10 in subframe 4 of SFN k+1.

[0196] As shown in Figure 20, the SBFD mapping is: SSB#1 is mapped to RO#1 and RO#2 in subframe 3 of SFN k, SSB#2 is mapped to RO#3 and RO#4 in subframe 4 of SFN k, SSB#3 is mapped to RO#5 and RO#6 in subframe 8 of SFN k, SSB#4 is mapped to RO#7 and RO#8 in subframe 9 of SFN k, and SSB#5 is mapped to RO#9 and RO#10 in subframe 3 of SFN k+1.

[0197] Two Separate PRACH Configurations

[0198] In accordance with example embodiments, an SBFD UE may be configured with at least two PRACH configurations. For example, the SBFD UE may be configured with a “non-SBFD PRACH configuration” for non-SBFD OFDM symbols and an “SBFD PRACH configuration” for SBFD OFDM symbols. In some embodiments, the at least two PRACH configuration may can completely overlap without preamble partitioning. For example, in embodiments where the communications device applies a mapping comprising the first validity condition to one of the PRACH configurations and another mapping comprising the fourth validity condition to the another of the PRACH configurations, ambiguity is avoided at the gNB as explained previously. In general, however, the at least two PRACH configurations may be different. For example, there may be non-overlapping ROs between the PRACH configurations and / or the preambles in overlapping ROs between the PRACH configurations are different. In embodiments where the at least two PRACH configurations are different, ambiguity does not arise at the gNB.

[0199] In some embodiments, where the SBFD UE is configured with a non-SBFD PRACH configuration and an SBFD PRACH configuration, the SBFD UE uses a mapping for the non- SBFD PRACH configuration which uses the first valid RO determination method, where ROs in SBFD OFDM symbols are invalid ROs and ROs in UL OFDM symbols are valid ROs.

[0200] In some embodiments, where the SBFD UE is configured with a non-SBFD PRACH configuration and an SBFD PRACH configuration, the SBFD UE uses a mapping for the SBFD PRACH configuration which uses the fourth valid determination method, where ROs in UL OFDM symbols are invalid ROs and ROs in UL subband of SBFD OFDM symbols are valid ROs.

[0201] In some other embodiments, where the SBFD UE is configured with a non-SBFD PRACH configuration and an SBFD PRACH configuration, the SBFD UE uses a mapping for the SBFD PRACH configuration which uses the second or the third valid determination method, where ROs in UL OFDM symbols and ROs in UL subband of SBFD OFDM symbols are valid ROs. For the case of the third valid determination method, ROs that are partially in UL OFDM symbols and UL subband of SBFD OFDM symbols are also valid ROs.

[0202] As an example, consider an FR1 TDD system with 5 SSBs and with the PRACH Configurations for Legacy TDD, SBFD and Non-SBFD in Table 3.

[0203] Table 3. PRACH Configurations for Legacy TDD, SBFD and Non-SBFD

[0204] According to Table 3, the ROs for all 3 PRACH Configurations (i.e. the legacy PRACH configuration, SBFD PRACH configuration and non-SBFD PRACH configuration) do not overlap. However, in some embodiments, the SBFD and non-SBFD PRACH configurations comprise one or more overlapping ROs. In such embodiments, these PRACH configurations are determined by the gNB such that the SSB-RO mapping for these PRACH configurations does not cause ambiguity at the gNB.

[0205] The number of valid ROs prior to SSB-RO association, for each PRACH configuration is:

[0206] • For Legacy PRACH configuration with PRACH Configuration Index = 127, each PRACH Configuration Period of 10 ms contains 2 PRACH slots in Subframes 4 and 9 (which are UL slots), where in each PRACH slot, there are 2 time domain ROs, and with FDM = 2, gives 8 valid ROs per PRACH Configuration Period.

[0207] • For SBFD PRACH configuration with PRACH Configuration Index = 125, each PRACH Configuration Period of 10 ms contains 2 PRACH slots in Subframes 2 and 7, which are both SBFD slots, where in each PRACH slot, there are 2 time domain ROs, and with FDM = 1 , gives 4 valid ROs per PRACH Configuration Period. In this example, the fourth valid RO determination method is used.

[0208] • For Non-SBFD PRACH configuration with PRACH Configuration Index = 124, each PRACH Configuration Period of 10 ms contains 1 PRACH slots in Subframes 9, which is UL slot, where in each PRACH slot, there are 2 time domain ROs, and with FDM = 2, gives 4 valid ROs per PRACH Configuration Period.

[0209] The SSB-RO Association Periods for all 3 of the PRACH Configurations are 20 ms (2* PRACH Configuration Period). In some embodiments, the SSB-RO Association period for each of the 3 PRACH configuration period is not the same.

[0210] The resultant SSB-RO mappings for a non-SBFD PRACH configuration, an SBFD PRACH configuration and a legacy PRACH configuration are shown in Figure 21.

[0211] As shown in Figure 21 , the non-SBFD mapping is: SSB#1 is mapped to RO#1 in subframe 9 of SFN k, SSB#2 is mapped to RO#2 in subframe 9 of SFN k, SSB#3 is mapped to RO#3 in subframe 9 of SFN k, SSB#4 is mapped to RO#4 in subframe 9 of SFN k, and SSB#5 is mapped to RO#5 in subframe 9 of SFN k+1.

[0212] As shown in Figure 21, the SBFD mapping is: SSB#1 is mapped to RO#1 in subframe 2 of SFN k, SSB#2 is mapped to RO#2 in subframe 2 of SFN k, SSB#3 is mapped to RO#3 in subframe 7 of SFN k, SSB#4 is mapped to RO#4 in subframe 7 of SFN k, and SSB#5 is mapped to RO#5 in subframe 2 of SFN k+1.

[0213] As shown in Figure 21 , the legacy TDD mapping is: SSB#1 is mapped to RO#1 and RO#2 in subframe 4 of SFN k, SSB#2 is mapped to RO#3 and RO#4 in subframe 4 of SFN k, SSB#3 is mapped to RO#5 and RO#6 in subframe 9 of SFN k, SSB#4 is mapped to RO#7 and RO#8 in subframe 9 of SFN k, and SSB#5 is mapped to RO#9 and RO#10 in subframe 4 of SFN k+1.

[0214] SBFD UE uses legacy PRACH Configuration

[0215] In some embodiments, for the case where the SBFD UE has one or more separate PRACH Configurations, it can still use the ROs in the legacy PRACH Configuration. This recognizes that the SBFD UE is a later release UE and hence it can understand legacy the signaling for legacy PRACH Configuration. However, if it uses the ROs from legacy PRACH Configuration, the gNB would assume that it is not using SBFD features for the RACH process, since the gNB may not be able to distinguish whether the UE transmitting the PRACH is from legacy UE or SBFD UE.

[0216] Differentiating SBFD UEs and Legacy UEs

[0217] The gNB may schedule a Msg 3 in a UL subband of SBFD OFDM symbols to utilise the additional UL resources provided by SBFD slot formats compared with legacy TDD slot formats. However, only SBFD UEs can successfully receive the Msg 3 if it is transmitted in a UL subband of SBFD symbols. Since the gNB does not know whether a given UE is an SBFD or a non-SBFD UE, this may lead to the gNB attempting and failing to transmit Msg 3 to non- SBFD UEs. Such failed transmissions decrease communications efficiency.

[0218] There is therefore a need for methods, communications devices and infrastructure equipment which can improve communications efficiency.

[0219] Distinguished by RO

[0220] In some embodiments, where an SBFD UE is configured with an SBFD PRACH configuration and a non-SBFD PRACH configuration, the gNB may determine that the UE is an SBFD UE if the gNB receives a PRACH in an RO in the SBFD PRACH configuration or in the non-SBFD PRACH configuration. The gNB may determine that the UE is a legacy UE if the gNB receives a PRACH in an RO in a legacy PRACH configuration. In such embodiments, the gNB configures the PRACH configurations such that the ROs in the legacy PRACH configuration do not overlap with the ROs in the SBFD or non-SBFD PRACH configurations.

[0221] If the gNB determines that a UE is an SBFD UE, the gNB may transmit Msg3 to the SBFD UE in a UL subband of SBFD OFDM symbols, thereby improving communications efficiency.

[0222] Preamble Partitioning

[0223] In some embodiments, if one or more ROs in UL OFDM symbols are shared between an SBFD UE and a legacy UE, the preambles in the one or more ROs are partitioned to distinguish between SBFD UE and legacy UE. For example, SBFD UE is configured to use preambles 0 to 31 , whilst legacy UE is configured to use preambles 32 to 63. Therefore, the gNB may determine, based on the preamble used, whether the UE transmitting a PRACH in the RO is a UE or SBFD UE.

[0224] In some embodiments, preamble partitioning is used only for ROs in UL OFDM symbols. Such embodiments are particularly advantageous in cases where a separate PRACH Configurations is used for SBFD and legacy UE (see section on Single Separate PRACH Configurations above). Since only SBFD UEs can use the ROs in SBFD OFDM symbols, there is no need to have preamble partitioning for these ROs as any PRACH transmitted using these ROs would indicate that the UE is capable of SBFD. On the other hand, a PRACH transmitted in ROs in UL OFDM symbols may be from a legacy UE or SBFD UE and hence, preamble partitioning may be used to distinguish them. In such embodiments, preamble partitioning is only applied to ROs in UL OFDM symbols, and is thus more efficient than if preamble partitioning was applied to al ROs.

[0225] PDCCH Order

[0226] For Contention Free RACH Access (CFRA), a gNB transmits a PDCCH Order to a UE to instruct the UE to start a RACH process. The PDCCH Order comprises a Mask Index which indicates the RO Index which the UE should use to transmit its PRACH. The PDCCH order may be sent when the UE is in connected mode. Therefore, the gNB knows exactly which UE it is sending the PDCCH order to, and the gNB knows whether that UE is SBFD or legacy UE. The gNB may inform the UE which preamble and which RO (per SSB) to use. However, at the time of sending the PDCCH order, the gNB is not aware of the SSB selected by the RO.

[0227] In some embodiments, in addition to the Mask Index, the PDCCH Order also comprises an indication of whether the UE should transmit using SBFD ROs / preambles or legacy ROs / preambles.

[0228] In some embodiments, in addition to the Mask Index, the PDCCH Order also comprises an indication of a PRACH configuration which the Mask Index applies to. In some embodiments, the indication of the PRACH configuration which the Mask index applies to comprises an indication of a set of ROs in the PRACH configuration which the Mask Index applies to. Such embodiments are particularly beneficial when there are a plurality of PRACH configurations as there may be ambiguity as to which PRACH Configurations the RO Index indicated in the PDDCH Order is for.

[0229] In some embodiments, a PRACH configuration transmitted from the gNB to a UE comprises an indication of a plurality of mappings between ROs and SSBs to be applied by the communications device (for example, an SBFD mapping and a non-SBFD mapping). The ROs in the PRACH configurations are mapped according to each of the plurality of mappings such that the ROs are indexed differently according to one of the mappings compared to another one of the mappings. The PDCCH order may, in addition to the mask index, may comprise an indication of which of the mappings the mask index applies to.

[0230] The following numbered paragraphs provide further example aspects and features of the present technique:

[0231] Paragraph 1 . A method of operating a subband full duplex, SBFD, communications device, the method comprising determining one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, the one or more validity conditions comprising a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, wherein the determining at least one of the mappings further comprises associating each of the SSBs with a preconfigured number of the valid ROs.

[0232] Paragraph 2. A method according to paragraph 1, wherein the determining one or more mappings between the plurality of ROs and the plurality of SSBs comprises determining a first and second mapping, wherein the determined at least one mapping is the first mapping, and the determining the second mapping comprises determining valid ROs for the second mapping by applying one or more validity conditions for the second mapping to the plurality of ROs configured in the communications resources of the wireless access interface, associating each of the SSBs with the preconfigured number of the valid ROs for the second mapping.

[0233] Paragraph 3. A method according to paragraph 2, wherein the validity conditions for the first mapping comprise the first validity condition and the validity conditions for the second mapping comprise the second condition, or the validity conditions for the first mapping comprise the second condition and the validity conditions for the second mapping comprise the first validity condition.

[0234] Paragraph 4. A method according to paragraph 2, wherein the validity conditions for the first mapping comprise the first validity condition, the first mapping is determined before the second mapping, and the second mapping comprises a third validity condition that valid ROs must not have already been mapped according to the first mapping, or the validity conditions for the second mapping comprise the first validity condition, the second mapping is determined before the first mapping, and the first mapping comprises a third validity condition that that valid ROs must not have already been mapped according to the second mapping.

[0235] Paragraph 5. A method according to paragraph 4, wherein the validity conditions for the first mapping comprise the third validity condition and the validity conditions for the first mapping comprise the second validity condition, or the validity conditions for the second mapping comprise the third validity condition and the validity conditions for the second mapping comprise the second validity condition.

[0236] Paragraph 6. A method according to paragraph 4, wherein the validity conditions for the first mapping comprise the third validity condition and the validity conditions for the first mapping comprise a fourth validity condition, or the validity conditions for the second mapping comprise the third validity condition and the validity conditions for the second mapping comprise the fourth validity condition, wherein the fourth validity condition is a condition that valid ROs must be completely contained either within uplink OFDM symbols in the communications resources of the wireless access interface or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

[0237] Paragraph 7. A method according to paragraph 4, wherein the validity conditions for the first mapping comprise the third validity condition and the validity conditions for the first mapping comprise a fifth validity condition, or the validity conditions for the second mapping comprise the third validity condition and the validity conditions for the second mapping comprise the fifth validity condition, wherein the fifth validity condition is a condition that valid ROs must be completely contained within uplink OFDM symbols in the communications resources of the wireless access interface, or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or a part of a valid RO is contained in uplink OFDM symbols in the communications resources of the wireless access interface and the other part of the valid RO is contained in an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

[0238] Paragraph 8. A method according to any of paragraphs 1 to 7, wherein the one or more validity conditions comprise a condition that an RO is invalid if there is less than a predefined number (Ngap) of OFDM symbols between any one of the SSBs and the start of the RO.

[0239] Paragraph 9. A method according any of paragraphs 1 to 8, wherein the one or more invalidity conditions comprise a condition that an RO is invalid if the RO is in the same slot as any one of the SSBs and the RO precedes the SSB in the slot.

[0240] Paragraph 10. A method according to any of paragraphs 1 to 9, wherein the configuration of the ROs in the communications resources of the wireless access interface is a first PRACH configuration and the SBFD communications device is configured with a second PRACH configuration comprising a plurality of ROs in the communications resources of the wireless access interface, wherein the first PRACH configuration and the second PRACH configuration are different, and the method comprises determining one or more mappings between the plurality of ROs in the second PRACH configuration and the plurality of SSBs, wherein determining at least one of the mappings between the plurality of ROs in the second PRACH configuration and the plurality of SSBs comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs in the second PRACH configuration, and associating each of the SSBs with a preconfigured number of the valid ROs in the second PRACH configuration.

[0241] Paragraph 11. A method according to paragraph 10, wherein the validity conditions for the determined at least one mapping for the first PRACH configuration comprise the first validity condition and the validity conditions for the determined at least one mapping for the second PRACH configuration comprise the second validity condition, or the validity conditions for the determined at least one mapping for the first PRACH configuration comprises the second validity condition and then the validity conditions for the determined at least one mapping for the second PRACH configuration comprise the first validity condition.

[0242] Paragraph 12. A method according to paragraph 10, wherein the validity conditions for the determined at least one mapping for the first PRACH configuration comprise the first validity condition and the validity conditions for the determined at least one mapping for the second PRACH configuration comprise a fourth validity condition, wherein the fourth validity condition is a condition that valid ROs must be completely contained either within uplink OFDM symbols in the communications resources of the wireless access interface or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or the validity conditions for the determined at least one mapping for the first PRACH configuration comprise the second validity condition and the validity conditions for the determined at least one mapping for the second PRACH configuration comprise the fourth validity condition.

[0243] Paragraph 13. A method according to paragraph 10, wherein the validity conditions for the first PRACH configuration comprise the first validity condition and the validity conditions for the determined at least one mapping for the second PRACH configuration comprise a fifth validity condition that valid ROs must be completely contained within uplink OFDM symbols in the communications resources of the wireless access interface, or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or a part of a valid RO is contained in uplink OFDM symbols in the communications resources of the wireless access interface and the other part of the valid RO is contained in an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface the validity conditions for the determined at least one mapping for the first PRACH configuration comprises the second validity condition and the validity conditions for the determined at least one mapping for the second PRACH configuration comprises the fifth validity condition.

[0244] Paragraph 14. A method according to any of paragraphs 10 to 13, wherein the ROs in the first PRACH configuration are separated in frequency with respect to the ROs in the second PRACH configuration.

[0245] Paragraph 15. A method according to any of paragraphs 1 to 14, wherein the method comprises receiving one or more of the SSBs from the infrastructure equipment, selecting one of the SSBs received from the infrastructure equipment, selecting one of the plurality of ROs for transmitting a PRACH to the infrastructure equipment, the selected RO being an RO associated with the selected the SSB according to the determined at least one mapping, and transmitting a PRACH to the infrastructure equipment in the selected RO.

[0246] Paragraph 16. A method of operating infrastructure equipment of a wireless communications network, the method comprising transmitting an indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment, transmitting, to the SBFD communications device, an indication to determine a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein the indication to determine the plurality of mappings comprises, for each mapping, an indication of one or more validity conditions to apply to the plurality of ROs to determine the mapping, wherein the one or more validity conditions for at least one of the mappings comprises a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

[0247] Paragraph 17. A method of operating a subband full duplex, SBFD, communications device, the method comprising receiving, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured for a non-SBFD communications device, and the method comprises determining one or more mappings between the plurality of ROs in the first PRACH configuration and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs in the first PRACH configuration, and associating each of the SSBs with a preconfigured number of the valid ROs.

[0248] Paragraph 18. A method according to paragraph 17, wherein the one or more validity conditions applied by the SBFD communications device comprise a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or a fourth validity condition that valid ROs must be completely contained either within uplink OFDM symbols in the communications resources of the wireless access interface or completely contained within uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or a fifth validity condition that valid ROs must be completely contained within uplink OFDM symbols in the communications resources of the wireless access interface, or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or a part of a valid RO is contained in uplink OFDM symbols in the communications resources of the wireless access interface and the other part of the valid RO is contained in an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

[0249] Paragraph 19. A method of operating infrastructure equipment of a wireless communications network, the method comprising transmitting an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment, transmitting an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration comprising a plurality of ROs configured for the non-SBFD communications device in the communications resources of the wireless access interface, wherein the first PRACH configuration and the second PRACH configuration are different.

[0250] Paragraph 20. A method according to paragraph 19, comprising receiving a PRACH from the SBFD communications device in one of the ROs in the first PRACH configuration, and transmitting a response signal to the SBFD communications device in response to the PRACH, the response signal being completely contained in an uplink subband of SBFD OFDM symbols of the wireless access interface, or a part of the response signal is contained in an uplink subband of SBFD OFDM symbols of the wireless access interface and the other part of the response signal is contained in uplink OFDM symbols of the wireless access interface.

[0251] Paragraph 21. A method according to paragraph 20, wherein the response signal is Msg3.

[0252] Paragraph 22. A method according to any of paragraphs 19 to 21 , comprising transmitting an indication of a third PRACH configuration to the SBFD communications device, the third PRACH configuration comprising a plurality of ROs configured for the SBFD communications device in communications resources of the wireless access interface, wherein the first PRACH configuration and the third PRACH configuration are different, and the method comprises receiving a PRACH from the SBFD communications device in one of the ROs in the first or third PRACH configuration and / or receiving a PRACH from the non-SBFD communications device in one of the ROs in the second PRACH configuration.

[0253] Paragraph 23. A method according to paragraph 22, comprising receiving a PRACH from the SBFD communications device in one of the ROs in the third PRACH configuration, and transmitting a response signal to the SBFD communications device in response to the PRACH, the response signal being completely contained in an uplink subband of SBFD OFDM symbols of the wireless access interface, or a part of the response signal is contained in an uplink subband of SBFD OFDM symbols of the wireless access interface and the other part of the response signal is contained in uplink OFDM symbols of the wireless access interface.

[0254] Paragraph 24. A method according to paragraph 23, wherein the response signal is Msg3.

[0255] Paragraph 25. A method according to any of paragraphs 19 to 23 comprising transmitting a plurality of synchronisation signal blocks (SSBs) on a plurality of downlink beams. Paragraph 26. A method of operating a subband full duplex, SBFD, communications device, the method comprising determining one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, and associating each of the SSBs with a preconfigured number of the valid ROs.

[0256] Paragraph 27. A method according to paragraph 26, wherein the method comprises receiving one or more of the SSBs from the infrastructure equipment, selecting one of the SSBs received from the infrastructure equipment, selecting one of the plurality of ROs for transmitting a PRACH to the infrastructure equipment, the selected RO being an RO associated with the selected the SSB according to the determined at least one mapping, and transmitting a PRACH to the infrastructure equipment in the selected RO using one of the preambles configured for use by SBFD communications devices.

[0257] Paragraph 28. A method of operating infrastructure equipment of a wireless communications network, the method comprising transmitting an indication of a Physical Random Access Channel (PRACH) configuration to a communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the communications device, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices.

[0258] Paragraph 29. A method according to paragraph 28, wherein the method comprises transmitting a plurality of synchronisation signal blocks (SSBs) on a respective plurality of downlink beams, receiving a PRACH from the communications device in one of the ROs, and transmitting a response signal to the communications device, wherein if a preamble of the PRACH received from the communications device is one of the preambles configured for use by SBFD communications devices, the response signal is completely contained in an uplink subband of SBFD OFDM symbols of the wireless access interface, or a part of the response signal is contained in an uplink subband of SBFD OFDM symbols of the wireless access interface and the other part of the response signal is contained in uplink OFDM symbols of the wireless access interface, or if the preamble of the PRACH received from the communications device is one of the preambles configured for use by non-SBFD communications devices, the response signal is completely contained in uplink OFDM symbols of the wireless access interface.

[0259] Paragraph 30. A method of operating a subband full duplex, SBFD, communications device, the method comprising receiving, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured for a non-SBFD communications device, and the method comprises receiving a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication that the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration.

[0260] Paragraph 31. A method of operating infrastructure equipment of a wireless communications network, the method comprising transmitting an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device, transmitting an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration indicating a plurality of ROs configured in the communications resources of the wireless access interface for the non- SBFD communications device, transmitting a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device and / or the non-SBFD communications device to instruct the SBFD communications device and / or the non-SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of whether the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration or the second PRACH configuration.

[0261] Paragraph 32. A method of operating a subband full duplex, SBFD, communications device, the method comprising receiving, from infrastructure equipment of a wireless communications network, an indication of a Physical Random Access Channel (PRACH) configuration, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, and the method comprises receiving a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

[0262] Paragraph 33. A method of operating infrastructure equipment of a wireless communications network, the method comprising transmitting an indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, and the method comprises transmitting a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device to instruct the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

[0263] Paragraph 34. A subband full duplex, SBFD, communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to determine one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, the one or more validity conditions comprising a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, wherein the determining at least one of the mappings further comprises associating each of the SSBs with a preconfigured number of the valid ROs.

[0264] Paragraph 35. Infrastructure equipment for a wireless communications network, the infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit an indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment, transmit, to the SBFD communications device, an indication to determine a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein the indication to determine the plurality of mappings comprises, for each mapping, an indication of one or more validity conditions to apply to the plurality of ROs to determine the mapping, wherein the one or more validity conditions for at least one of the mappings comprises a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

[0265] Paragraph 36. A subband full duplex, SBFD, communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured for a non-SBFD communications device, wherein the controller is configured in combination with the transmitter and the receiver to determine one or more mappings between the plurality of ROs in the first PRACH configuration and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs in the first PRACH configuration, and associating each of the SSBs with a preconfigured number of the valid ROs.

[0266] Paragraph 37. Infrastructure equipment for a wireless communications network, the infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment, transmit an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration comprising a plurality of ROs configured for the non-SBFD communications device in the communications resources of the wireless access interface, wherein the first PRACH configuration and the second PRACH configuration are different. Paragraph 38. A subband full duplex, SBFD, communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to determine one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, and associating each of the SSBs with a preconfigured number of the valid ROs.

[0267] Paragraph 39. Infrastructure equipment for a wireless communications network, the infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit an indication of a Physical Random Access Channel (PRACH) configuration to a communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the communications device, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices.

[0268] Paragraph 40. A subband full duplex, SBFD, communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured for a non-SBFD communications device, wherein the controller is configured in combination with the transmitter and the receiver to receive a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication that the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration.

[0269] Paragraph 41. Infrastructure equipment for a wireless communications network, the infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device, transmit an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration indicating a plurality of ROs configured in the communications resources of the wireless access interface for the non- SBFD communications device, transmit a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device and / or the non-SBFD communications device to instruct the SBFD communications device and / or the non-SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of whether the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration or the second PRACH configuration.

[0270] Paragraph 42. A subband full duplex, SBFD, communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive, from infrastructure equipment of a wireless communications network, an indication of a Physical Random Access Channel (PRACH) configuration, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, wherein the controller is configured in combination with the transmitter and the receiver to receive a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

[0271] Paragraph 43. Infrastructure equipment for a wireless communications network, the infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, wherein the controller is configured in combination with the transmitter and the receiver to transmit a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device to instruct the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

[0272] Paragraph 44. Circuitry for a subband full duplex, SBFD, communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to determine one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, the one or more validity conditions comprising a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, wherein the determining at least one of the mappings further comprises associating each of the SSBs with a preconfigured number of the valid ROs.

[0273] Paragraph 45. Circuitry for infrastructure equipment for a wireless communications network, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to transmit an indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment, transmit, to the SBFD communications device, an indication to determine a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein the indication to determine the plurality of mappings comprises, for each mapping, an indication of one or more validity conditions to apply to the plurality of ROs to determine the mapping, wherein the one or more validity conditions for at least one of the mappings comprises a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

[0274] Paragraph 46. Circuitry for a subband full duplex, SBFD, communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to receive, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured for a non-SBFD communications device, wherein the controller circuitry is configured in combination with the transmitter circuitry and the receiver circuitry to determine one or more mappings between the plurality of ROs in the first PRACH configuration and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs in the first PRACH configuration, and associating each of the SSBs with a preconfigured number of the valid ROs.

[0275] Paragraph 47. Circuitry for infrastructure equipment for a wireless communications network, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to transmit an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment, transmit an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration comprising a plurality of ROs configured for the non-SBFD communications device in the communications resources of the wireless access interface, wherein the first PRACH configuration and the second PRACH configuration are different.

[0276] Paragraph 48. Circuitry for a subband full duplex, SBFD, communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to determine one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, and associating each of the SSBs with a preconfigured number of the valid ROs.

[0277] Paragraph 49. Circuitry for infrastructure equipment for a wireless communications network, t the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to transmit an indication of a Physical Random Access Channel (PRACH) configuration to a communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the communications device, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices.

[0278] Paragraph 50. Circuitry for a subband full duplex, SBFD, communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to receive, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured for a non-SBFD communications device, wherein the controller circuitry is configured in combination with the transmitter circuitry and the receiver circuitry to receive a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication that the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration.

[0279] Paragraph 51. Circuitry for infrastructure equipment for a wireless communications network, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to transmit an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device, transmit an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration indicating a plurality of ROs configured in the communications resources of the wireless access interface for the non- SBFD communications device, transmit a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device and / or the non-SBFD communications device to instruct the SBFD communications device and / or the non-SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of whether the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration or the second PRACH configuration.

[0280] Paragraph 52. Circuitry for a subband full duplex, SBFD, communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to receive, from infrastructure equipment of a wireless communications network, an indication of a Physical Random Access Channel (PRACH) configuration, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, wherein the controller circuitry is configured in combination with the transmitter circuitry and the receiver circuitry to receive a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

[0281] Paragraph 53. Circuitry for infrastructure equipment for a wireless communications network, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to transmit indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, wherein the controller circuitry is configured in combination with the transmitter circuitry and the receiver circuitry to transmit a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device to instruct the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

[0282] Paragraph 54. A computer program which, when the program is executed by a computer, cause the computer to perform the method of any of paragraphs 1 to 33.

[0283] Paragraph 55. A non-transitory computer-readable storage medium storing a computer program according to paragraph 54.

[0284] 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.

[0285] It will be appreciated by one skilled in the art that references to pre-defining information for a communications device in the specifications (such as 3GPP specifications) means that this information is preconfigured, or “hard-wired”, in the communications device.

[0286] 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.

[0287] 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

[0288] [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[0289] [2] TR 38.913, “Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14)”, 3rd Generation Partnership Project, v14.3.0, August 2017.

[0290] [3] RP-213591 , “New SI: Study on evolution of NR duplex operation,” CMCC, RAN#94e, December 2021.

[0291] [4] RP-220633, “Revised SID: Study on evolution of NR duplex operation,” CMCC, RAN#95e, March 2022. [5] European Patent No. 3545716.

[0292] [6] TS38.211 “Physical channels and modulation (Rel-18),” v18.0.0, 3GPP

[0293] [7] TS38.213, “Physical layer procedures for control (Rel-18),” v18.0, 3GPP.

Claims

CLAIMS1. A method of operating a subband full duplex, SBFD, communications device, the method comprising determining one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, the one or more validity conditions comprising a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, wherein the determining at least one of the mappings further comprises associating each of the SSBs with a preconfigured number of the valid ROs.

2. A method according to claim 1 , wherein the determining one or more mappings between the plurality of ROs and the plurality of SSBs comprises determining a first and second mapping, wherein the determined at least one mapping is the first mapping, and the determining the second mapping comprises determining valid ROs for the second mapping by applying one or more validity conditions for the second mapping to the plurality of ROs configured in the communications resources of the wireless access interface, associating each of the SSBs with the preconfigured number of the valid ROs for the second mapping.

3. A method according to claim 2, wherein the validity conditions for the first mapping comprise the first validity condition and the validity conditions for the second mapping comprise the second condition, or the validity conditions for the first mapping comprise the second condition and the validity conditions for the second mapping comprise the first validity condition.

4. A method according to claim 2, wherein the validity conditions for the first mapping comprise the first validity condition, the first mapping is determined before the second mapping, and the second mapping comprises a third validity condition that valid ROs must not have already been mapped according to the first mapping, or the validity conditions for the second mapping comprise the first validity condition, the second mapping is determined before the first mapping, and the first mapping comprises a third validity condition that that valid ROs must not have already been mapped according to the second mapping.

5. A method according to claim 4, wherein the validity conditions for the first mapping comprise the third validity condition and the validity conditions for the first mapping comprise the second validity condition, or the validity conditions for the second mapping comprise the third validity condition and the validity conditions for the second mapping comprise the second validity condition.

6. A method according to claim 4, wherein the validity conditions for the first mapping comprise the third validity condition and the validity conditions for the first mapping comprise a fourth validity condition, or the validity conditions for the second mapping comprise the third validity condition and the validity conditions for the second mapping comprise the fourth validity condition, wherein the fourth validity condition is a condition that valid ROs must be completely contained either within uplink OFDM symbols in the communications resources of the wireless access interface or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

7. A method according to claim 4, wherein the validity conditions for the first mapping comprise the third validity condition and the validity conditions for the first mapping comprise a fifth validity condition, or the validity conditions for the second mapping comprise the third validity condition and the validity conditions for the second mapping comprise the fifth validity condition, wherein the fifth validity condition is a condition that valid ROs must be completely contained within uplink OFDM symbols in the communications resources of the wireless access interface, or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or a part of a valid RO iscontained in uplink OFDM symbols in the communications resources of the wireless access interface and the other part of the valid RO is contained in an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

8. A method according to claim 1 , wherein the one or more validity conditions comprise a condition that an RO is invalid if there is less than a predefined number (Ngap) of OFDM symbols between any one of the SSBs and the start of the RO.

9. A method according claim 1 , wherein the one or more invalidity conditions comprise a condition that an RO is invalid if the RO is in the same slot as any one of the SSBs and the RO precedes the SSB in the slot.

10. A method according to claim 1 , wherein the configuration of the ROs in the communications resources of the wireless access interface is a first PRACH configuration and the SBFD communications device is configured with a second PRACH configuration comprising a plurality of ROs in the communications resources of the wireless access interface, wherein the first PRACH configuration and the second PRACH configuration are different, and the method comprises determining one or more mappings between the plurality of ROs in the second PRACH configuration and the plurality of SSBs, wherein determining at least one of the mappings between the plurality of ROs in the second PRACH configuration and the plurality of SSBs comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs in the second PRACH configuration, and associating each of the SSBs with a preconfigured number of the valid ROs in the second PRACH configuration.

11. A method according to claim 10, wherein the validity conditions for the determined at least one mapping for the first PRACH configuration comprise the first validity condition and the validity conditions for the determined at least one mapping for the second PRACH configuration comprise the second validity condition, or the validity conditions for the determined at least one mapping for the first PRACH configuration comprises the second validity condition and then the validity conditions for the determined at least one mapping for the second PRACH configuration comprise the first validity condition.

12. A method according to claim 10, wherein the validity conditions for the determined at least one mapping for the first PRACH configuration comprise the first validity condition and the validity conditions for the determined at least one mapping for the second PRACH configuration comprise a fourth validity condition, wherein the fourth validity condition is a condition that valid ROs must be completely contained either within uplink OFDM symbols in the communications resources of the wireless access interface or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or the validity conditions for the determined at least one mapping for the first PRACH configuration comprise the second validity condition and the validity conditions for the determined at least one mapping for the second PRACH configuration comprise the fourth validity condition.

13. A method according to claim 10, wherein the validity conditions for the first PRACH configuration comprise the first validity condition and the validity conditions for the determined at least one mapping for the second PRACH configuration comprise a fifth validity condition that valid ROs must be completely contained within uplink OFDM symbols in the communications resources of the wireless access interface, or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or a part of a valid RO is contained in uplink OFDM symbols in the communications resources of the wireless access interface and the other part of the valid RO is contained in an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface the validity conditions for the determined at least one mapping for the first PRACH configuration comprises the second validity condition and the validity conditions for the determined at least one mapping for the second PRACH configuration comprises the fifth validity condition.

14. A method according to claim 10, wherein the ROs in the first PRACH configuration are separated in frequency with respect to the ROs in the second PRACH configuration.

15. A method according to claim 1 , wherein the method comprises receiving one or more of the SSBs from the infrastructure equipment, selecting one of the SSBs received from the infrastructure equipment, selecting one of the plurality of ROs for transmitting a PRACH to the infrastructure equipment, the selected RO being an RO associated with the selected the SSB according to the determined at least one mapping, and transmitting a PRACH to the infrastructure equipment in the selected RO.

16. A method of operating infrastructure equipment of a wireless communications network, the method comprising transmitting an indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment, transmitting, to the SBFD communications device, an indication to determine a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein the indication to determine the plurality of mappings comprises, for each mapping, an indication of one or more validity conditions to apply to the plurality of ROs to determine the mapping, wherein the one or more validity conditions for at least one of the mappings comprises a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

17. A method of operating a subband full duplex, SBFD, communications device, the method comprising receiving, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured for a non-SBFD communications device, and the method comprises determining one or more mappings between the plurality of ROs in the first PRACH configuration and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs in the first PRACH configuration, and associating each of the SSBs with a preconfigured number of the valid ROs.

18. A method according to claim 17, wherein the one or more validity conditions applied by the SBFD communications device comprise a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or a fourth validity condition that valid ROs must be completely contained either within uplink OFDM symbols in the communications resources of the wireless access interface or completely contained within uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or a fifth validity condition that valid ROs must be completely contained within uplink OFDM symbols in the communications resources of the wireless access interface, or completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, or a part of a valid RO is contained in uplink OFDM symbols in the communications resources of the wireless access interface and the other part of the valid RO is contained in an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

19. A method of operating infrastructure equipment of a wireless communications network, the method comprising transmitting an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment, transmitting an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration comprising a plurality of ROs configured for the non-SBFD communications device in the communications resources of the wireless access interface, wherein the first PRACH configuration and the second PRACH configuration are different.

20. A method according to claim 19, comprising receiving a PRACH from the SBFD communications device in one of the ROs in the first PRACH configuration, and transmitting a response signal to the SBFD communications device in response to the PRACH, the response signal being completely contained in an uplink subband of SBFD OFDM symbols of the wireless access interface, or a part of the response signal is containedin an uplink subband of SBFD OFDM symbols of the wireless access interface and the other part of the response signal is contained in uplink OFDM symbols of the wireless access interface.21 . A method according to claim 20, wherein the response signal is Msg3.

22. A method according to claim 19, comprising transmitting an indication of a third PRACH configuration to the SBFD communications device, the third PRACH configuration comprising a plurality of ROs configured for the SBFD communications device in communications resources of the wireless access interface, wherein the first PRACH configuration and the third PRACH configuration are different, and the method comprises receiving a PRACH from the SBFD communications device in one of the ROs in the first or third PRACH configuration and / or receiving a PRACH from the non-SBFD communications device in one of the ROs in the second PRACH configuration.

23. A method according to claim 22, comprising receiving a PRACH from the SBFD communications device in one of the ROs in the third PRACH configuration, and transmitting a response signal to the SBFD communications device in response to the PRACH, the response signal being completely contained in an uplink subband of SBFD OFDM symbols of the wireless access interface, or a part of the response signal is contained in an uplink subband of SBFD OFDM symbols of the wireless access interface and the other part of the response signal is contained in uplink OFDM symbols of the wireless access interface.

24. A method according to claim 23, wherein the response signal is Msg3.

25. A method according to claim 19 comprising transmitting a plurality of synchronisation signal blocks (SSBs) on a plurality of downlink beams.

26. A method of operating a subband full duplex, SBFD, communications device, the method comprisingdetermining one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, and associating each of the SSBs with a preconfigured number of the valid ROs.

27. A method according to claim 26, wherein the method comprises receiving one or more of the SSBs from the infrastructure equipment, selecting one of the SSBs received from the infrastructure equipment, selecting one of the plurality of ROs for transmitting a PRACH to the infrastructure equipment, the selected RO being an RO associated with the selected the SSB according to the determined at least one mapping, and transmitting a PRACH to the infrastructure equipment in the selected RO using one of the preambles configured for use by SBFD communications devices.

28. A method of operating infrastructure equipment of a wireless communications network, the method comprising transmitting an indication of a Physical Random Access Channel (PRACH) configuration to a communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the communications device, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices.

29. A method according to claim 28, wherein the method comprises transmitting a plurality of synchronisation signal blocks (SSBs) on a respective plurality of downlink beams, receiving a PRACH from the communications device in one of the ROs, andtransmitting a response signal to the communications device, wherein if a preamble of the PRACH received from the communications device is one of the preambles configured for use by SBFD communications devices, the response signal is completely contained in an uplink subband of SBFD OFDM symbols of the wireless access interface, or a part of the response signal is contained in an uplink subband of SBFD OFDM symbols of the wireless access interface and the other part of the response signal is contained in uplink OFDM symbols of the wireless access interface, or if the preamble of the PRACH received from the communications device is one of the preambles configured for use by non-SBFD communications devices, the response signal is completely contained in uplink OFDM symbols of the wireless access interface.

30. A method of operating a subband full duplex, SBFD, communications device, the method comprising receiving, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured for a non-SBFD communications device, and the method comprises receiving a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication that the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration.31 . A method of operating infrastructure equipment of a wireless communications network, the method comprising transmitting an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device, transmitting an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration indicating a plurality of ROs configured in the communications resources of the wireless access interface for the non- SBFD communications device,transmitting a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device and / or the non-SBFD communications device to instruct the SBFD communications device and / or the non-SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of whether the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration or the second PRACH configuration.

32. A method of operating a subband full duplex, SBFD, communications device, the method comprising receiving, from infrastructure equipment of a wireless communications network, an indication of a Physical Random Access Channel (PRACH) configuration, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, and the method comprises receiving a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

33. A method of operating infrastructure equipment of a wireless communications network, the method comprising transmitting an indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, and the method comprises transmitting a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device to instruct the SBFD communications device to transmit a PRACH tothe infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

34. A subband full duplex, SBFD, communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to determine one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, the one or more validity conditions comprising a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, wherein the determining at least one of the mappings further comprises associating each of the SSBs with a preconfigured number of the valid ROs.

35. Infrastructure equipment for a wireless communications network, the infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit an indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment,transmit, to the SBFD communications device, an indication to determine a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein the indication to determine the plurality of mappings comprises, for each mapping, an indication of one or more validity conditions to apply to the plurality of ROs to determine the mapping, wherein the one or more validity conditions for at least one of the mappings comprises a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

36. A subband full duplex, SBFD, communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured for a non-SBFD communications device, wherein the controller is configured in combination with the transmitter and the receiver to determine one or more mappings between the plurality of ROs in the first PRACH configuration and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs in the first PRACH configuration, and associating each of the SSBs with a preconfigured number of the valid ROs.

37. Infrastructure equipment for a wireless communications network, the infrastructure equipment comprising a transmitter configured to transmit signals,a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment, transmit an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration comprising a plurality of ROs configured for the non-SBFD communications device in the communications resources of the wireless access interface, wherein the first PRACH configuration and the second PRACH configuration are different.

38. A subband full duplex, SBFD, communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to determine one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, and associating each of the SSBs with a preconfigured number of the valid ROs.

39. Infrastructure equipment for a wireless communications network, the infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver totransmit an indication of a Physical Random Access Channel (PRACH) configuration to a communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the communications device, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices.

40. A subband full duplex, SBFD, communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured for a non-SBFD communications device, wherein the controller is configured in combination with the transmitter and the receiver to receive a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication that the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration.41 . Infrastructure equipment for a wireless communications network, the infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to transmit an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device,transmit an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration indicating a plurality of ROs configured in the communications resources of the wireless access interface for the non- SBFD communications device, transmit a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device and / or the non-SBFD communications device to instruct the SBFD communications device and / or the non-SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of whether the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration or the second PRACH configuration.

42. A subband full duplex, SBFD, communications device comprising a transmitter configured to transmit signals, a receiver configured to receive signals, and a controller configured in combination with the transmitter and the receiver to receive, from infrastructure equipment of a wireless communications network, an indication of a Physical Random Access Channel (PRACH) configuration, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, wherein the controller is configured in combination with the transmitter and the receiver to receive a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

43. Infrastructure equipment for a wireless communications network, the infrastructure equipment comprising a transmitter configured to transmit signals, a receiver configured to receive signals, anda controller configured in combination with the transmitter and the receiver to transmit indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, wherein the controller is configured in combination with the transmitter and the receiver to transmit a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device to instruct the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

44. Circuitry for a subband full duplex, SBFD, communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to determine one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, the one or more validity conditions comprising a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface, wherein the determining at least one of the mappings further comprisesassociating each of the SSBs with a preconfigured number of the valid ROs.

45. Circuitry for infrastructure equipment for a wireless communications network, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to transmit an indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment, transmit, to the SBFD communications device, an indication to determine a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein the indication to determine the plurality of mappings comprises, for each mapping, an indication of one or more validity conditions to apply to the plurality of ROs to determine the mapping, wherein the one or more validity conditions for at least one of the mappings comprises a first validity condition that valid ROs must be completely contained within uplink Orthogonal Frequency Division Multiplexing, OFDM, symbols in the communications resources of the wireless access interface, or a second validity condition that valid ROs must be completely contained within an uplink subband of SBFD OFDM symbols in the communications resources of the wireless access interface.

46. Circuitry for a subband full duplex, SBFD, communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to receive, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communicationsresources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured for a non-SBFD communications device, wherein the controller circuitry is configured in combination with the transmitter circuitry and the receiver circuitry to determine one or more mappings between the plurality of ROs in the first PRACH configuration and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs in the first PRACH configuration, and associating each of the SSBs with a preconfigured number of the valid ROs.

47. Circuitry for infrastructure equipment for a wireless communications network, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to transmit an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by infrastructure equipment, transmit an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration comprising a plurality of ROs configured for the non-SBFD communications device in the communications resources of the wireless access interface, wherein the first PRACH configuration and the second PRACH configuration are different.

48. Circuitry for a subband full duplex, SBFD, communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to determine one or more mappings between a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wirelessaccess interface provided by infrastructure equipment of a wireless communications network and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices, wherein determining at least one of the mappings comprises determining valid ROs by applying one or more validity conditions to the plurality of ROs configured in the communications resources of the wireless access interface, and associating each of the SSBs with a preconfigured number of the valid ROs.

49. Circuitry for infrastructure equipment for a wireless communications network, t the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to transmit an indication of a Physical Random Access Channel (PRACH) configuration to a communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the communications device, each RO supporting a plurality of preambles, one or more of the preambles being configured for use by SBFD communications devices and one or more others of the preambles being configured for use by non-SBFD communications devices.

50. Circuitry for a subband full duplex, SBFD, communications device, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to receive, from infrastructure equipment of a wireless communications network, an indication of a first Physical Random Access Channel (PRACH) configuration, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the first PRACH configuration is different from a second PRACH configuration configured fora non-SBFD communications device, wherein the controller circuitry is configured in combination with the transmitter circuitry and the receiver circuitry to receive a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication that the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration.51 . Circuitry for infrastructure equipment for a wireless communications network, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to transmit an indication of a first Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the first PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device, transmit an indication of a second PRACH configuration to a non-SBFD communications device, the second PRACH configuration indicating a plurality of ROs configured in the communications resources of the wireless access interface for the non- SBFD communications device, transmit a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device and / or the non-SBFD communications device to instruct the SBFD communications device and / or the non-SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of whether the index of the RO in which the PRACH is to be transmitted is an index of one of the ROs in the first PRACH configuration or the second PRACH configuration.

52. Circuitry for a subband full duplex, SBFD, communications device, the circuitry comprising transmitter circuitry configured to transmit signals,receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to receive, from infrastructure equipment of a wireless communications network, an indication of a Physical Random Access Channel (PRACH) configuration, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured for the SBFD communications device in communications resources of a wireless access interface provided by the infrastructure equipment, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, wherein the controller circuitry is configured in combination with the transmitter circuitry and the receiver circuitry to receive a Physical Downlink Control Channel, PDCCH, Order from the infrastructure equipment instructing the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, wherein the PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

53. Circuitry for infrastructure equipment for a wireless communications network, the circuitry comprising transmitter circuitry configured to transmit signals, receiver circuitry configured to receive signals, and controller circuitry configured in combination with the transmitter circuitry and the receiver circuitry to transmit indication of a Physical Random Access Channel (PRACH) configuration to a sub-band full duplex, SBFD, communications device, the PRACH configuration comprising a plurality of Physical Random Access Channel (PRACH) Occasions (ROs) configured in communications resources of a wireless access interface provided by infrastructure equipment for the SBFD communications device, wherein the PRACH configuration comprises an indication of a plurality of mappings between the plurality of ROs and a plurality of synchronisation signal blocks (SSBs) to be transmitted by the infrastructure equipment on a plurality of respective downlink beams, the ROs in each of the mappings being indexed, wherein the controller circuitry is configured in combination with the transmitter circuitry and the receiver circuitry to transmit a Physical Downlink Control Channel, PDCCH, Order to the SBFD communications device to instruct the SBFD communications device to transmit a PRACH to the infrastructure equipment, the PDCCH order comprising an index of an RO in which the PRACH is to be transmitted, whereinthe PDCCH order for the SBFD communications device comprises an indication of one of the plurality of mappings to which the index of the RO applies.

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

55. A non-transitory computer-readable storage medium storing a computer program according to claim 54.

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