Methods, communications devices, and infrastructure equipment

Abstract

A method of operating infrastructure equipment of a wireless communications network for communicating with one or more communications devices is provided. The method comprises transmitting an indication of additional physical random access channel (PRACH) resources reserved for use by the communications devices to transmit PRACH preamble during a random access channel (RACH) procedure, transmitting control information comprising at least one condition for the communications devices to determine whether the communications devices are allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

Description

[0001] METHODS, COMMUNICATIONS DEVICES, AND INFRASTRUCTURE EQUIPMENT

[0002] BACKGROUND

[0003] Field of Disclosure

[0004] The present disclosure relates to communications devices and infrastructure equipment of wireless communications networks and methods of operating such communications devices and infrastructure equipment. The present application claims the Paris convention priority to European patent application EP24204451.9 filed on 3 October 2024, the content of which is incorporated herein by reference in its entirety.

[0005] Description of Related Art

[0006] 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.

[0007] 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.

[0008] Current and future wireless communications networks are expected to routinely and efficiently support communications with an ever-increasing range of devices associated with a wider range of data traffic profiles and types than existing systems are optimised to support. For example, it is expected future wireless communications networks will be expected to efficiently support communications with devices including reduced complexity devices, machine type communication (MTC) devices, high resolution video displays, virtual reality headsets, extended Reality (XR) and so on. Some of these different types of devices may be deployed in very large numbers, for example low complexity devices for supporting the “The Internet of Things”, and may typically be associated with the transmissions of relatively small amounts of data with relatively high latency tolerance. Other types of device, for example supporting high-definition video streaming, may be associated with transmissions of relatively large amounts of data with relatively low latency tolerance. Other types of device, for example used for autonomous vehicle communications and for other critical applications, may be characterised by data that should be transmitted through the network with low latency and high reliability. A single device type might also be associated with different traffic profiles / characteristics depending on the application(s) it is running. For example, different 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).

[0009] In view of this there is expected to be a desire for current wireless communications networks, for example those which may be referred to as 5G or new radio (NR) systems / new radio access technology (RAT) systems, or indeed future 6G wireless communications, as well as future iterations / releases of existing systems, to efficiently support connectivity for a wide range of devices associated with different applications and different characteristic data traffic profiles and requirements. 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.

[0010] SUMMARY OF THE DISCLOSURE

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

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

[0013] Embodiments of the present technique can provide a method of operating infrastructure equipment of a wireless communications network for communicating with one or more communications devices. The method comprises transmitting an indication of additional physical random access channel (PRACH) resources reserved for use by the communications devices to transmit PRACH preamble during a random access channel (RACH) procedure, and transmitting control information comprising at least one condition for the communications devices to determine whether the communications devices are allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

[0014] According to example embodiments, access to additional PRACH resources, which are allocated for use by the communications devices, can be controlled by the network.

[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 an NR-type 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 is a message flow diagram showing a typical four-step random access (RACH) procedure;

[0022] Figure 5 is a message flow diagram showing a typical two-step RACH procedure;

[0023] Figure 6 schematically illustrates the components of an SSB;

[0024] Figure 7 schematically illustrates an SSB burst set transmitted on SSB beams;

[0025] Figure 8 schematically illustrates an example of an on-demand SSB;

[0026] Figure 9 illustrates a part schematic, part message flow diagram representation of a wireless communications system comprising a communications device and infrastructure equipment in accordance with embodiments;

[0027] Figure 10 is a flow diagram illustrating a method of operating infrastructure equipment of a wireless communications network in accordance with example embodiments; Figure 11 is a flow diagram illustrating a method of operating an NES communications device in accordance with example embodiments.

[0028] DETAILED DESCRIPTION OF THE EMBODIMENTS

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

[0030] 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.

[0031] The network 6 includes a plurality of base stations 1 connected to a core network 2, which may be for example an Evolved Packet Core (EPC). 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.

[0032] Data is transmitted from base stations 1 to communications devices 4 within their respective coverage areas 3 via a radio downlink (DL). Data is transmitted from communications devices 4 to the base stations 1 via a radio uplink (UL). The core network 2 routes data to and from the communications devices 4 via the respective base stations 1 and provides functions such as authentication, mobility management, charging and so on. Communications devices may also be referred to as mobile stations, user equipment (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.

[0033] Base stations, which are an example of network infrastructure equipment, may also be referred to as transceiver stations, nodeBs, eNodeBs, eNB, gNodeBs, gNB and so forth. In this regard different terminology is often associated with different generations of wireless telecommunications systems for elements providing broadly comparable functionality. However, certain embodiments of the disclosure may be equally implemented in different generations of wireless telecommunications systems, and for simplicity certain terminology may be used regardless of the underlying network architecture. That is to say, the use of a specific term in relation to certain example implementations is not intended to indicate these implementations are limited to a certain generation of network that may be most associated with that particular terminology.

[0034] New Radio Access Technology (5G)

[0035] 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],

[0036] 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 be for example referred to as 5GC) which may contain all other functions required to transmit data for communicating to and from the wireless communications devices and the core network 20 may be connected to other networks 25.

[0037] 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.

[0038] 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.

[0039] In terms of broad top-level functionality, the core network 20 connected to the new RAT telecommunications system represented in Figure 2 may be broadly considered to correspond with the core network 2 represented in Figure 1, and the respective central units 40 and their associated distributed units / TRPs 10 may be broadly considered to provide functionality corresponding to the base stations 1 of Figure 1. The term network infrastructure equipment / access node may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may lie with the controlling node / central unit and / or the distributed units / TRPs. A communications device 14 is represented in Figure 2 within the coverage area of the first communication cell 12. This communications device 14 may thus exchange signalling with the first central unit 40 in the first communication cell 12 via one of the distributed units / TRPs 10 associated with the first communication cell 12.

[0040] 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.

[0041] Thus, certain embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems / networks according to various different architectures, such as the example architectures shown in Figures 1 and 2. It will thus be appreciated the specific wireless telecommunications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, certain embodiments of the disclosure may be described generally in the context of communications between network infrastructure equipment / access nodes and a communications device, wherein the specific nature of the network infrastructure equipment / access node and the communications device will depend on the network infrastructure for the implementation at hand. For example, in some scenarios the network infrastructure equipment / access node may comprise a base station, such as an LTE-type base station 1 as shown in Figure 1 which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment may comprise a control unit / controlling node 40 and / or a TRP 10 of the kind shown in Figure 2 which is adapted to provide functionality in accordance with the principles described herein.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] The interface 46 between the DU 42 and the CU 40 is known as the F 1 interface which can be a physical or a logical interface. The Fl interface 46 between CU and DU may operate in accordance with 3GPP technical specifications [3] and [4], and may be formed from a fibre optic or other wired or wireless high bandwidth connection. In one example the connection 16 from the TRP 10 to the DU 42 is via fibre optic. The connection between a TRP 10 and the core network 20 can be generally referred to as a backhaul, which comprises the interface 16 from the network interface 50 of the TRP 10 to the DU 42 and the Fl interface 46 from the DU 42 to the CU 40.

[0046] As will be appreciated by those acquainted with 5G architecture, the CU 40 may be a logical node which hosts Radio Resource Control (RRC) protocols, Service Data Adaptation Protocols (SDAP), and Packet Data Convergence Protocols (PDCP) of a gNB. Alternatively, the CU 40 may be a logical node which hosts RRC and PDCP protocols of an en-gNB (which is a gNB that is able to connect with both EPC and eNBs and can be understood as being, for example, a secondary node (SgNB) used in dual connectivity scenarios). The CU 40 partly controls the operation of one or more DUs 40 and terminates the Fl interface 46 for the DUs that it controls. The DU 42 may be a logical node which hosts Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) layers of a gNB or en-gNB. The operation of the DU 42 is partly controlled by the CU 40 for which the DU 42 terminates the F 1 interface 46.

[0047] Although not shown in Figures 2 or 3, it will be familiar to those acquainted with 5G architecture that the CU 40 may be further split into a CU-CP which performs the control plane functions of the CU 40 and a CU-UP which performs the user plane functions of the CU 40 (see for example, [5]). In more detail, the CU-CP may be a logical node hosting an RRC protocol and a control plane part of a PDCP protocol of the CU 40 for the gNB or en-gNB. The CU-CP terminates an El interface connected with the CU-UP and an Fl-C interface connected with the DU 42. As will be appreciated, the Fl -C interface carries control plane signalling of the Fl interface 46. The CU-UP may be a logical node which hosts a user plane part of a PDCP protocol of the CU 40 for an en-gNB. Alternatively, the CU-UP may be a logical node which hosts a user plane part of the PDCP protocol and an SDAP protocol of the CU 40 for a gNB. The CU-UP terminates an El interface connected with the CU-CP and an Fl-U interface connected with the DU 42. As will be appreciated, the Fl-U interface carries user plane signalling of the Fl interface 46.

[0048] Random Access (RACH) Procedures

[0049] In wireless communications networks, such as LTE and NR type networks, a random access procedure may be used by communications devices to perform initial access with the wireless communications network. The random access procedure involves the communications device transmitting a preamble on a physical random access channel (PRACH), and so the procedure is commonly referred to as a RACH or PRACH procedure / process. The RACH procedure may be a two-step RACH procedure or a four-step RACH procedure as described in more detail below.

[0050] In addition, there exists Radio Resource Control (RRC) modes for communications devices. For example, it is common to support an RRC idle mode (RRC IDLE) and an RRC connected mode (RRC CONNECTED). A communications device in the RRC IDLE mode may transition to RRC CONNECTED mode, for example because it needs to transmit uplink data or respond to a paging request, by undertaking a random access procedure.

[0051] In addition to a communications device deciding itself to initiate a random access procedure to connect to the wireless communications network, it is also possible for the wireless communications network, e.g. a base station, to instruct a communications device in an RRC CONNECTED mode to initiate a random access procedure by transmitting to the communications device an instruction to do so. Such an instruction is sometimes referred to as a PDCCH order (Physical Downlink Control Channel order). There are various scenarios in which a network-triggered RACH procedure (PDCCH order) may arise.

[0052] Figure 4 shows a typical four-step RACH procedure used in LTE systems such as that described by reference to Figure 1 which could also be applied to an NR wireless communications system such as that described by reference to Figure 2. A communications device (or UE), which may be in an RRC IDLE mode for example, may have some data which it needs to send to the network. To do so, the UE sends a random access preamble 51 (message 1) to a gNB. When the gNB detects the random access preamble 51, the gNB determines a random access preamble index / identity (RAPID) of the random access preamble 51. Assuming the random access preamble 51 is successfully received by the gNB, the gNB will transmit a random access response 52 message (message 2) to the communications device(s). The random access response 52 message may include the determined RAPID to indicate that the random access response 52 message is for the communications device(s) which transmitted the random access preamble 51 with that RAPID. The random access response 52 message carries a timing advance value such that the communications device can change its UL timing to compensate for the round trip delay caused by its distance from the gNB and grant uplink resources for the communications device to transmit the data in.

[0053] Following the reception of the random access response message 52, the communications device transmits the scheduled transmission of data 53 to the gNB (message 3), using the identity assigned to it in the random access response message 52. Assuming there are no collisions with other UEs, which may occur if another UE and the communications device send the same random access preamble 51 to the gNB at the same time and using the same frequency resources, the scheduled transmission of data 53 is successfully received by the gNB. The gNB will respond to the scheduled transmission 53 with a contention resolution message 54 (message 4).

[0054] In 5G / NR systems, an “inactive” RRC mode (RRC INACTIVE) may be used, where a UE is able to start data transfer with a low delay in the RRC INACTIVE mode without transition to the RRC CONNECTED mode. Various possible solutions have been proposed to permit this, one of which is a two-step RACH procedure. As will be appreciated, compared with the four-step RACH process, the two-step RACH process can provide a facility for transmitting data more quickly. Accordingly, it has been proposed to develop general MAC procedures covering both physical layer and higher layer aspects for the two-step RACH process. In general, the benefit of the two-step RACH procedure compared with the four-step RACH procedure is to reduce the time it takes for connection setup / resume procedure. For example, in an ideal situation, the two-step RACH will reduce the latency by halving the number of steps from four to two for initial access UEs. In addition, it is considered that a two-step RACH procedure has potential benefits for channel access in NR unlicensed spectrum (NR-U).

[0055] Broadly, the two-step RACH allows the combination of the transmission of the random access preamble 51 with the transmission of data 53 of Figure 4 as an initial transmission (“Message A” or “MsgA”), and similarly the combination of the transmission of the random access response 52 and contention resolution message 54 as a response (“Message B”, or “MsgB”). A fallback procedure may be provided to allow a RACH procedure which is started according to the specifications for a two-step RACH to instead proceed according to the four-step RACH procedure. Two-step RACH may be performed by communications devices in the RRC IDLE, RRC INACTIVE or RRC CONNECTED modes.

[0056] A message flow diagram illustrating the two-step RACH process is shown in Figure 5. As its name suggests, in the two-step RACH process, there are only two-steps as noted above. In the first step, the UE transmits a Message A 55 which comprises a RACH preamble 56 and data 57. The data 57 is transmitted on a shared uplink channel, such as a physical uplink shared channel, PUSCH that in a four-step RACH procedure would be transmitted in Message 3. More specifically, the choice of a particular preamble 56 may pre-configure the communications device to transmit the data 57 in pre-configured resources of the uplink shared channel. In the second step, the base station, having successfully received the Message A 55, responds with a Message B 58 which incorporates both a RAR, as would be carried by message 2 of the four-step RACH procedure described above, and the corresponding contention resolution and / or data (PDSCH) that in a four-step RACH procedure would be transmitted in Message 4.

[0057] Synchronisation Signal Block (SSB)

[0058] As will be known to one skilled in the art, the Synchronisation Signal Block (SSB) (also called as SS / PBCH block) is used for initial access and cell reselection. An example of an SSB is schematically illustrated in Figure 6.

[0059] 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. For initial cell selection, the UE assumes a periodicity of 20ms.

[0060] An SSB burst set comprises a set of one or more time-multiplexed SSBs. Each SSB transmitted in a burst set uses 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 transmitted periodically.

[0061] 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).

[0062] 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 measured 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.

[0063] 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).

[0064] The measurement of the RSRP of an SSB may be referred to as “SS-RSRP”. The measurement of the RSRP of an SSB may comprise measuring the RSRP on resource elements where SSS is transmitted. Alternatively, or in addition, the measurement of the RSRP of an SSB may comprise measuring the RSRP on resource elements where PBCH DMRS is transmitted.

[0065] In other examples, the measured signal quality of an SSB may be a Reference Signal Received Quality (SS-RSRQ) of the SSB. The SS-RSRQ is defined as the ratio of N x SS-RSRP / RSSI (Received Signal Strength Indicator), where N is the number of resource blocks. For example, the RSSI in NR is measured in one or more OFDM symbols in a SS / PBCH Block Measurement Time Configuration (SMTC). The SMTC is a configuration to the UE to set time window for measurement by using SSB. The OFDM symbols used for RSSI measurement can be configured by higher layers.

[0066] In initial access, after determining the uplink beam, the UE initiates a RACH procedure by transmitting PRACH on the determined uplink beam. For example, the UE may transmit message 51 or message 55 on the determined uplink beam. The PRACH may be transmitted on PRACH resources which have been configured for the UE to transmit the PRACH as part of initial access. For example, the PRACH may be transmitted in one of a plurality of RACH Occasions (ROs) configured for transmitting the PRACH.

[0067] Network Energy Saving (NES)

[0068] 3GPP is currently discussing network energy saving (NES). By reducing energy consumption in wireless communications networks, the impact of wireless communications on the environment can be reduced. For example, if less energy is consumed in wireless communications networks, fewer fossil fuels are burned, there are fewer greenhouse gas emissions and therefore environmental sustainability is improved. Furthermore, the reduction of energy consumption in wireless communications networks can reduce costs incurred by network operators.

[0069] 5G / NR can handle advanced services and applications requiring very high data rates (for example, XR). Additionally, 5G / NR networks are becoming denser, using more antennas, and utilising larger bandwidths and an increasing number of frequency bands. Therefore, in at least some cases, energy consumption in 5G / NR is increasing. Since 5G / NR is becoming increasingly pervasive across various industries and geographical areas, it is becoming increasingly important to reduce the environmental impact of 5G / NR networks. NES solutions are therefore required.

[0070] In addition, energy consumption has become a key part of the operating expenses (OPEX) for network operators. According to a report from the Global System for Mobile Communications (GSMA) [6], the energy cost of mobile networks accounts for approximately 23% of total operator costs. Most of the energy consumption comes from the radio access network and in particular from the Active Antenna Unit (AAU), with data centres and fibre transport accounting for a smaller share of the energy consumption. The energy consumption of a radio access network can be split into two parts: (1) a dynamic part which is only consumed when data transmission / reception is ongoing, and (2) a static part which is consumed all the time to maintain the necessary operation of the radio access network equipment, even when data transmission / reception is not on-going. Further details on NES can be found in [7], In Release 19 of the 3GPP standards, an NES work item has been approved ([8]). The objectives of the work item are the following:

[0071] 1. Specify procedures and signaling method(s) to support on-demand SSB SCell operation for UEs in connected mode configured with CA, for both intra- / inter-band CA.

[0072] 2. Specify procedures and signaling method(s) to support on-demand SIB1 for UEs in idle / inactive mode, including:

[0073] 3. Specify adaptation of common signal / channel transmissions.

[0074] NES System Information (SI)

[0075] As will be understood by a person skilled in the art, system information is transmitted by infrastructure equipment of a wireless communications network to communications devices in a cell provided by the infrastructure equipment. The system information informs the communications devices on how to access services provided by the wireless communications network. The system information comprises a master information block (MIB), system information block type 1 (SIB 1) and a plurality of other system information blocks (SIBs). The MIB is broadcasted in the PBCH in each SSB.

[0076] The MIB comprises information required to decode SIB 1. For example, MIB comprises a cell barred bit, system frame number, and a PDCCH configuration for SIB1, for example. SIB1 comprises information required for performing initial access (for example, random access parameters such as time / frequency resources for PRACH (e.g. a RACH occasions (RO) configuration), preambles, or barring parameters). In initial access, the UE transmits a PRACH in an RO of the RO configuration indicated by SIB1, thereby initiating a random access procedure. After the random access procedure, the UE may enter the RRC Connected mode. Therefore, MIB and SIB1 together provide all the information which is required for initial access Accordingly, SIB1 is defined as the “remaining minimum SI”. SIB1 may comprise scheduling information of the other SIBs (for example, mapping of SIBs to SI messages, periodicity of other SIBs and Si-window size). SIB1 is periodically broadcasted over a downlink shared channel (DL- SCH), but may be provided on-demand as explained below. Periodically broadcasted SIB1 is typically an “always-on” signal. The information comprised in the other SIBs is not required for initial access and so SIB1 may comprise an indication of whether the other SIBs are provided on-demand, in which case, SIB1 may also comprise an indication of a PRACH configuration for use by the UE to request the other SIBs. SIB 1 may also comprise radio resource configuration information common to all communications devices in the cell in which the SIB1 is transmitted. SIB1 may also comprise cell barring information.

[0077] The other SIBs may comprise one or more of: SIB2-SIB19 and SIBpos.

[0078] — SIB2 comprises cell re-selection information, mainly related to the serving cell;

[0079] — SIB3 comprises information about the serving frequency and intra-frequency neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters);

[0080] — SIB4 comprises information about other NR frequencies and inter-frequency neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters), which can also be used for NR idle / inactive measurements;

[0081] — SIB5 comprises information about E-UTRA frequencies and E-UTRA neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters);

[0082] — SIB6 comprises an ETWS primary notification; — SIB7 comprises an ETWS secondary notification;

[0083] — SIB 8 comprises a CMAS warning notification;

[0084] — SIB9 comprises information related to GPS time and Coordinated Universal Time (UTC);

[0085] — SIB 10 comprises the Human-Readable Network Names (HRNN) of the NPNs listed in SIB 1 ;

[0086] — SIB 11 comprises information related to idle / inactive measurements;

[0087] — SIB 15 comprises information related to disaster roaming;

[0088] — SIB 16 comprises slice-based cell reselection information;

[0089] — SIB 17 comprises information related to TRS configuration for UEs in

[0090] RRC IDLE / RRC INACTIVE;

[0091] — SIBpos comprises positioning assistance data as defined in TS 37.355 and TS 38.331;

[0092] — SIB 18 comprises information related to the Group IDs for Network selection (GINs) associated with SNPNs listed in SIB1.

[0093] — SIB 19 comprising satellite assistance information related to non-terrestrial networks

[0094] Further information regarding existing SI can be found in TS38.300 vl8.0.0, the contents of which are hereby incorporated by reference in their entirety.

[0095] As mentioned above, the approved NES work item in Release 19 of the 3GPP standards has an objective to specify adaptations of common signal / channel transmissions. For example, adaptation of SSB transmissions, SIB1 transmissions and PRACH configurations are being considered for NES.

[0096] Adapted SSB and SIB1 Transmissions

[0097] In Release- 15 of the 3GPP standards, the time domain positions of transmitted SSBs within a half frame are semi-statically configured. Furthermore, UEs assume a single periodicity for the transmitted SSBs. For NES, the transmission pattern of SSB and / or SIB 1 transmissions can be adapted. For example, the transmission pattern of an SSB and / or SIB 1 may be adapted to change periodicity and / or the interval between time resource locations of SSB and / or SIB1 can also change. In another example, the transmission pattern of an SSB and / or SIB1 may be adapted to omit specified elements from the SSB and / or SIB 1. The transmission pattern can be adapted semi-statically or dynamically [8] .

[0098] On-demand SIB 1

[0099] As one example of an adaptation, it has been suggested to introduce an on-demand SIB 1. In other words, instead of infrastructure equipment of the wireless communications network periodically broadcasting SIB1, it has been proposed for infrastructure equipment (i.e. NES infrastructure equipment) to broadcast SIB 1 only in response to a request (or trigger such as a wake-up signal) from a UE. Since the SIB 1 would thereby be transmitted less often, network energy savings would be increased. However, the details of such an on-demand SIB1 have not yet been discussed. Furthermore, existing UEs which do not support NES (also referred to as “non-NES UEs”) are configured to expect the SIB1 to be periodic. Since non- NES capable UEs are already deployed in wireless communications networks, it is important that NES solutions do not significantly impact performance for non-NES capable UEs.

[0100] It has also been suggested, instead of on-demand SIB1, and as another example of adaptation, to increase the period between successive SIB1 transmissions so that SIB Is are transmitted less often, thereby reducing network energy consumption.

[0101] Furthermore, as another example of adaptation, it has been suggested to introduce an on-demand SSB to improve network energy savings as will be discussed in more detail below. On-demand SSB

[0102] Typically, a gNB broadcasts SSBs periodically. SSB is an “always-on” signal. This means the gNB must be awake to transmit SSB, even when no active UE is camped on the cell provided by the gNB. Consequently, SSB transmissions lead to high network energy consumption. A solution to reduce the network energy consumption caused by the mandatory periodic, always-on SSB is to configure an “on- demand SSB”. In the case of on-demand SSB, the gNB does not transmit SSB until it receives an activation command. The activation command may be received by the gNB from other network infrastructure equipment, or from a UE, requesting the on-demand SSB transmission.

[0103] An example of on-demand SSB transmission will be described with reference to Figure 8. As shown in Figure 8, a UE, or other network infrastructure equipment aside from the gNB 82, transmits an on- demand SSB activation command 84 to a gNB 82. Before the UE, or the other network infrastructure equipment, transmits the activation command 84 to the gNB 82, there is a period 88 during which SSB is not transmitted by the gNB 82. In response to receiving the activation command 84, the gNB 82 broadcasts a plurality of SSBs 94 during a transmission period 90. Within the transmission period 90, the SSBs 94 may be broadcasted periodically as shown in Figure 8. The gNB 82 may broadcast one SSB burst set in response to the activation command 84. The gNB 82 may receive a deactivation command 86 from the UE (or another UE in the cell provided by the gNB 82, or other network infrastructure equipment) to stop transmitting SSB. In response to receiving the deactivation command 86, the gNB 82 may stop transmitting SSB. Therefore, there is a period 92 after receiving the deactivation command during which SSB is not transmitted by the gNB 82. In some examples, the gNB 82 may start a timer after receiving the activation command 84 and, then continue to transmit SSBs periodically while the timer is live and, when the timer expires, the gNB 82 may stop transmitting SSB.

[0104] In Release-19 of the 3GPP standards, on-demand SSB will be specified for secondary cells (SCells). However, it is envisaged that on-demand SSB may be applied to primary cell (Pcell) and primary SCG cell (PScell) in future releases.

[0105] It has also been suggested, instead of on-demand SSB, and as another example of adaptation, to increase the period between successive SSB transmissions so that SSBs are transmitted less often, thereby reducing network energy consumption.

[0106] As will be explained in more detail below, it is also being considered to perform time-domain adaptation of PRACH for NES.

[0107] Time-domain Adaptation of PRACH

[0108] One of the objectives for adaptation of common channels in Rel-19 NES WID is adaptation of PRACH in the time-domain.

[0109] Although the adaptation of SSB, SIB 1 and PRACH configurations are aimed at providing improved network energy savings, the implementation of these adaptations may cause technical problems. For example, if the period between successive transmission of SSB burst sets in a periodic SSB burst set transmission is increased, this will improve network energy savings because the gNB transmits SSB burst sets less often. However, since SSB is required for a UE to access the cell, this may increase delays in accessing the cell. Furthermore, since the interval between successive SSB burst set transmissions is greater, more UEs may have entered the cell since the last SSB burst set transmission and therefore may attempt to detect the same SSB. After this, the UEs will attempt to receive SIB 1 and then perform initial access. The UEs will then try to transmit PRACH. The PRACH collision rate is likely to increase due to the increased number of UEs. As another example, if the period between successive transmissions of SIB 1 in a periodic SIB 1 transmission is increased, this will improve network energy savings because the gNB transmits SIB 1 less often. However, since SIB1 is required for a UE to access the cell, this may increase delays in accessing the cell. Furthermore, since the interval between successive SIB1 transmissions is greater, more UEs may have entered the cell since the last SIB 1 transmission and therefore may attempt to detect the same SIB 1. After this, the UEs will attempt to perform initial access. The UEs will then try to transmit PRACH. The PRACH collision rate is likely to increase due to the increased number of UEs.

[0110] As another example, if the periodicity of PRACH resources is adapted to increase the period between PRACH resources (for example, RACH occasions), then network energy saving is improved because the gNB has to be awake less often to monitor the PRACH resources. However, after a UE receives SIB1, it will have to wait longer before it can transmit PRACH due to the increased period. Furthermore, since the period is increased, the likelihood of other UEs in the cell attempting to use the same PRACH resources to transmit PRACH is increased. Therefore, the PRACH collision rate is likely to increase.

[0111] Accordingly, adapting common signals / channels for network energy saving purposes may lead to increased delays and collision rates (and therefore communications resource wastage) in wireless communications networks. A better balance is needed between obtaining network energy savings and communications efficiency in wireless communications network.

[0112] There is therefore a need for improved methods, communications devices and infrastructure equipment which can address at least some of the problems identified above.

[0113] Additional PRACH Resources for NES communications devices

[0114] Figure 9 shows a part schematic, part message flow diagram representation of a wireless communications system in accordance with example embodiments. The wireless communications system comprises an NES communications device 62 (e.g. an NES UE), a non-NES communications device 66 (such as a non- NES UE) and infrastructure equipment 64 of a wireless communications network. The non-NES communications device 66 is a communications device which does not support NES functions.

[0115] The NES communications device 62 comprises a transceiver 62. 1 (or transceiver circuitry) and a controller 62.2 (or controller circuitry). The non-NES communications device 66 comprises a transceiver 66. 1 (or transceiver circuitry) and a controller 66.2 (or controller circuitry). The infrastructure equipment comprises a transceiver 64.1 (or transceiver circuitry) and a controller 64.2 (or controller circuitry). The transceivers 62.1, 64.1, 66.1 are configured to transmit and receive signals. The transceivers 62.1, 64.1, 66. 1 (or transceiver circuitry) may each comprise a separate transmitter or receiver (or separate transmitter and receiver circuitry), or the transceivers 62.1, 64.1, 66.1 (or transceiver circuitry) may each comprise a device (or circuitry) configured to perform both transmission and reception. Each of the controllers 62.2, 64.2, 66.2 may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc.

[0116] The infrastructure equipment 64 provides a cell for one or more communications devices in the cell. In the example of Figure 9, the NES communications device 62 and the non-NES communications device 66 are in the cell.

[0117] As shown in Figure 9, the controller 64.2 of the infrastructure equipment 64 controls the transceiver 64.1 of the infrastructure equipment to transmit 68 one or more synchronisation signal blocks (SSBs) in the cell. Each of the one or more SSBs comprise a master information block (MIB). As shown in Figure 9, the controller 62.2 of the NES communications device 62 controls the transceiver 62.1 to receive the one or more SSBs and the controller 66.2 of the non-NES communications device 66 controls the transceiver 66. 1 to receive the one or more SSBs.

[0118] As shown in Figure 9, the controller 64.2 of the infrastructure equipment 64 controls the transceiver 64.1 of the infrastructure equipment 64 to transmit 70 one or more SIBs of a first type in the cell. Each of the one or more SIBs of the first type comprise an indication of first Physical Random Access Channel (PRACH) resources for transmitting PRACH. Each MIB in the one or more SSBs comprises information required to decode the one or more SIBs of the first type.

[0119] In some embodiments, the first PRACH resources are for use by NES communications devices and non- NES communications devices in the cell to transmit PRACH. In some embodiments, the first PRACH resources are reserved for use by non-NES communications devices in the cell to transmit PRACH. As shown in Figure 9, the controller 62.2 of the NES communications device 62 controls the transceiver 62. 1 to receive the one or more SIBs and the controller 66.2 of the non-NES communications device 66 controls the transceiver 66. 1 to receive the one or more SIBs.

[0120] The indication of the first PRACH resources may indicate parameters of the PRACH resources such as a location of the PRACH resources in time and / or frequency. In cases where the first PRACH resources are periodic, the indication of the first PRACH resources may comprise a PRACH configuration index, for example.

[0121] The one or more SIBs of the first type transmitted by the infrastructure equipment 64 may be referred to as “system information block type 1 (SIB1)”. Indeed, example embodiments will be described below with reference to SIB1. However, example embodiments are not limited to the SIB1 currently defined in 3GPP specifications and are equally applicable to any future SIB which comprises an indication of PRACH resources for transmitting PRACH. Therefore, although example embodiments will refer specifically to SIB1, it should be understood that the present disclosure is not so limited and any SIB comprising an indication of PRACH resources for transmitting PRACH may be used.

[0122] As shown in Figure 9, the controller 64.2 of the infrastructure equipment 64 controls the transceiver 64.1 of the infrastructure equipment 64 to transmit 72 one or more DCI messages comprising an indication of additional PRACH resources reserved for use by NES communications devices in the cell to transmit PRACH and control information including conditions for the NES communications devices using the additional PRACH resources for transmitting PRACH. As shown in Figure 9, the controller 62.2 of the NES communications device 62 controls the transceiver 62. 1 to receive the indication of the additional PRACH resources and the control information including conditions for the NES communications devices using the additional PRACH resources for transmitting PRACH.

[0123] It is particularly beneficial to transmit the indication of additional PRACH resources and conditions for using the additional PRACH resources in DCI messages, since the communications devices keep monitoring the PDCCH for DCI messages even in inactive states, such as RRC idle mode and RRC inactive mode. This allows the communications devices to receive the indication of additional PRACH resources and conditions for using the additional PRACH resources to send RACH preambles in subsequent processes, for example, paging procedure or RRC resume procedure, without having to define new signalling between the infrastructure equipment and the communications devices. The one or more DCI messages transmitted by the infrastructure equipment 64 may be of different DCI formats. In some example embodiments, the one or more DCI messages may be of DCI format for scheduling of PDSCH, for example DCI format 1 0. In some other example embodiments, the one or more DCI messages may be of DCI formats for other purposes, for example DCI format 2 7 or DCI format 2 9. However, example embodiments are not limited to the DCI formats currently defined in 3GPP specifications and are equally applicable to any future DCI formats which comprises an indication of additional PRACH resources for transmitting PRACH and control information including conditions for using additional PRACH resources for transmitting PRACH. Therefore, although example embodiments refer specifically to DCI format 1 0, DCI format 2 7 or DCI format 2 9, it should be understood that the present disclosure is not so limited and any DCI formats comprising an indication of additional PRACH resources for transmitting PRACH and control information including conditions for using additional PRACH resources for transmitting PRACH may be used. In some embodiments, the indication of additional PRACH resources for transmitting PRACH and the control information including conditions for using additional PRACH resources for transmitting PRACH may be transmitted by means of reserved bits, which are fields within the DCI that are not used for any other specific purpose in a given configuration. These reserved bits serve as placeholders such that the DCI message length remains consistent for the purpose of backward compatibility or reserved usage in future versions of the protocol, thus allowing them to carry information related to the indication of additional PRACH resources and the conditions for using the additional PRACH resources.

[0124] In some embodiments, the indication of the additional PRACH resources comprises information identifying a configuration of the additional PRACH resources in time and / or frequency. For example, the indication of the additional PRACH resources may indicate parameters of the PRACH resources such as a location of the PRACH resources in time and / or frequency. In some embodiments, the indication of the additional PRACH resources comprises information identifying a configuration of RACH occasions in time and / or frequency. In some embodiments, the indication of the additional PRACH resources may indicate a subset of preambles that are configured for the additional PRACH resources. In cases where the additional PRACH resources are periodic, the indication of the additional PRACH resources may comprise a PRACH configuration index, for example. In some embodiments, the transmission of the information identifying the configuration of the additional PRACH resources may be a broadcast in the cell.

[0125] In some embodiments, the additional PRACH resources are periodic. In some embodiments, the additional PRACH resources may appear between the first PRACH resources in time. For example, the additional PRACH resources may be a periodic configuration of PRACH resources offset in time relative to the first PRACH resources such that one or more instances of the additional PRACH resources appear between instances of the first PRACH resources in time. In some embodiments, the additional PRACH resources may have a smaller period than the first PRACH resources.

[0126] By transmitting, in the cell and indication of additional PRACH resources reserved for use by NES communications devices to transmit PRACH, communications efficiency can be improved. For example, NES communications devices may use the first PRACH resources, or NES communications devices may use the additional PRACH resources to transmit PRACH. Non-NES communications devices may only use the first PRACH resources. Since there are additional PRACH resources, there may be a reduced delay for a given communications device to access the cell because it is more likely the next PRACH resource will not be far away in time. Furthermore, since there are additional PRACH resources, there may be a reduced collision rate because there are more PRACH resources available in which communications devices can transmit PRACH.

[0127] In accordance with example embodiments, when the infrastructure equipment transmits the indication of the additional PRACH resources and the control information including the conditions, the additional PRACH resources may already be activated for use by NES communications devices to transmit PRACH. In such embodiments, NES communications devices may make use of the additional PRACH resources to transmit PRACH immediately after the indication of additional PRACH resources is received and the indicated conditions are satisfied. In such embodiments, the infrastructure equipment may transmit, at a later time, a deactivation indication indicating that the additional PRACH resources have been deactivated. If the additional PRACH resources have been deactivated, they can no longer be used by NES communications devices to transmit PRACH while they are deactivated. At an even later time, the infrastructure equipment may transmit an activation signal indicating that the additional PRACH resources have been activated. In this case, the activation signal may be regarded as a “reactivation signal” because the additional PRACH resources are re-activated. NES communications devices may use the additional PRACH resources to transmit PRACH while they are activated. Whilst the additional PRACH resources are deactivated, the infrastructure equipment does not have to monitor them for PRACH - it can therefore go to sleep and save power.

[0128] In accordance with example embodiments, when the infrastructure equipment transmits the indication of the additional PRACH resources, the additional PRACH resources may be deactivated for use by NES communications devices to transmit PRACH. At a later time, the infrastructure equipment may transmit an activation signal indicating that the additional PRACH resources have been activated. In such embodiments, the infrastructure equipment may transmit, at an even later time, a deactivation indication indicating that the additional PRACH resources have been deactivated.

[0129] In some embodiments, the deactivation indication is transmitted in response to the infrastructure equipment detecting that a number of NES communications devices in the cell is below a pre-defined threshold. This recognises that the probability of delay to accessing the cell and of collision between communications devices in PRACH is lower if the number of NES communications devices in the cell is lower. Furthermore, the activation of PRACH resources may decrease network energy savings because the infrastructure equipment may have to monitor more resources for PRACH. Therefore, a balance between network energy savings and communications efficiency can be achieved in such embodiments.

[0130] In some embodiments, the activation indication may be transmitted in response to the infrastructure equipment detecting a collision between PRACHs at the infrastructure equipment. This indicates that communications efficiency is being adversely affected and, therefore, to improve communications efficiency additional PRACH resources are activated. In some embodiments, the infrastructure equipment may detect collisions between PRACHs based on energy above a threshold within an RO but cannot isolate a preamble sequence. In some other embodiments, the infrastructure equipment may detect collisions between PRACHs when a preamble detection correlator the infrastructure equipment shows more than a predefined number of distinct peaks.

[0131] In some embodiments, the activation indication is transmitted in response to the infrastructure equipment detecting that a number of NES communications devices in the cell is above a predefined threshold. In some embodiments, the infrastructure equipment may detect the number of NES communications devices in the cell by keeping a record of the communications devices reporting NES capability and comparing this count against predefined thresholds. In some other embodiments, the infrastructure equipment may estimate the number of NES communications devices in a cell which supports on-demand SIB1, from the frequency of the on-demand SIB1 requests being received.

[0132] This recognises that the probability of delay to accessing the cell and of collision between PRACHs is increased if the number of NES communications devices in the cell is higher. Furthermore, the deactivation of PRACH resources may increase network energy savings because the infrastructure equipment may have to monitor fewer resources for PRACH. Therefore, a balance between network energy savings and communications efficiency can be achieved in such embodiments. In some embodiments, the deactivation indication is transmitted in response to the infrastructure equipment not detecting a collision between PRACHs / or any preamble transmissions on the additional PRACH resources at the infrastructure equipment for a predefined time period. This indicates that communications efficiency is not being adversely affected and, therefore, to improve network energy savings, the additional PRACH resources are deactivated.

[0133] The activation indication and / or the deactivation indication may be broadcast in the cell by the infrastructure equipment, for example.

[0134] In some embodiments, the indication of additional PRACH resources and the control information including conditions are transmitted in response to an adaptation performed by the infrastructure equipment. The adaptation may comprise, for example:

[0135] — adapting a periodic transmission of an SSB burst set to increase the period between successive transmissions of the SSB burst sets,

[0136] — adapting a periodic transmission of the SIB 1 to increase the period between successive transmissions of the SIB1, and / or

[0137] — adapting a periodic configuration of RACH occasions (ROs) in the first PRACH resources to increase the period of the periodic configuration of the ROs in the first PRACH resources.

[0138] As explained previously, such adaptations may improve network energy saving, but may also decrease communications efficiency. By transmitting the indication of the additional PRACH resources and the control information including the conditions in response to the adaptation, this recognises that the additional PRACH resources may be needed to improve communications efficiency. It will be appreciated that, in some embodiments, such adaptations are not performed by the infrastructure equipment. For example, the infrastructure equipment may be initially configured to transmit periodic SSB burst sets with a large period between successive transmissions, to transmit periodic SIB1 with a large period between successive transmissions and / or the configuration of ROs in the first PRACH resources may be such that the period of the configuration of ROs is large. In such cases, the problems due to increased delay to access the cell and increased PRACH collisions still arise, even though no adaptation was performed by the infrastructure equipment.

[0139] For ease of explanation, embodiments may be described with reference to UEs and gNBs. However, the present disclosure is not so limited, and references to “UE” may be replaced with “communications device” and references to “gNB” may be replaced with “infrastructure equipment of a wireless communications network”.

[0140] Furthermore, references to “NES UEs” are UEs which support one or more NES functions and “NES cells” are cells which support one or more NES functions.

[0141] NES functions may comprise one or more of the following:

[0142] (1). Supporting anchor SSB with intervals between broadcasts with a periodicity of more than

[0143] 20 ms on an initial bandwidth part. An NES UE may be configured to receive SSBs with intervals between broadcasts with a periodicity of more than 20 ms on an initial bandwidth part. By contrast, a non-NES UE assumes that SSB is broadcast with a periodicity of 20 ms or less on the initial bandwidth part.

[0144] (2). Supporting on-demand SSB. An NES UE may be configured to request and receive on- demand SSBs. By contrast, a non-NES UE assumes SSB is always-on and periodically transmitted.

[0145] (3). Supporting on-demand SIB 1. An NES UE is configured to request and receive on- demand SIB 1. By contrast, a non-NES UE assumes SIB 1 is periodically transmitted with a periodicity of 160 ms.

[0146] In some embodiments, an NES UE is defined as a UE which supports: at least NES function (1), at least NES function (2), at least NES function (3), at least NES functions (1) and (2), at least NES functions (1) and (3), at least NES functions (2) and (3), at least NES functions (1), (2) and (3).

[0147] Non-NES UEs are UEs which do not support any of the NES functions supported by the NES UEs.

[0148] In some embodiments, the NES communications device may store the indication of the additional PRACH resources. For example, the NES communications device may be in a first cell provided by a first infrastructure equipment which transmits the indication of the additional PRACH resources to the NES communications device. Then, the NES communications device stores the indication of the additional PRACH resources. Then, when the NES communications device moves to a second cell provided by a second infrastructure equipment of the wireless communications network, the NES communications device may determine an area ID of the second cell provided by the other infrastructure equipment. The first and / or second infrastructure equipment may transmit the area ID to the NES communications device in system information (such as in SIB1 or SIB2-18), for example.

[0149] Based on the area ID, the NES communications device may determine that the additional PRACH resources are also reserved for use by NES communications devices in the second cell provided by the second infrastructure equipment. For example, the NES communications device may be preconfigured to know that infrastructure equipment with the same area ID have the same additional PRACH resources. In cases where both the first and second infrastructure equipment transmit the same area ID to the NES communications device, the NES communications device may compare the area ID transmitted by the first and second infrastructure equipment and, if the area ID received from the first and second infrastructure equipment is the same, the NES communications device determines that the additional PRACH resources are also reserved for use by NES communications devices in the second cell provided by the second infrastructure equipment. The NES communications device may then use the stored additional PRACH resources from the first cell to transmit PRACH in the second cell provided by the second infrastructure equipment. Such embodiments improve communications efficiency because the NES communications device does not need to receive an indication of additional PRACH resources every time it changes cells.

[0150] PRACH Resource Selection

[0151] In some embodiments, the NES communications device may randomly select between the first PRACH resources and the additional PRACH resources for transmitting a PRACH to the infrastructure equipment. This simplifies processing for the NES communications device.

[0152] In some embodiments, the NES communications device may transmit a PRACH to the infrastructure equipment using the first PRACH resources. The NES communications device may determine that the infrastructure equipment did not correctly receive the PRACH. In response, the NES communications device may transmit a PRACH in the additional PRACH resources. Such embodiments are useful for implicitly informing the infrastructure equipment whether the additional PRACH resources are currently being used to avoid PRACH collisions, and therefore allow the infrastructure equipment to determine whether to keep the additional PRACH resources activated. The NES communications device may determine that the infrastructure equipment did not correctly receive the PRACH because, for example, the NES communications device did not receive a response to the PRACH transmitted in the first PRACH resources or the NES communications device receives a random access response with backoff indication from the infrastructure equipment.

[0153] As explained above, the first PRACH resources may be for use by NES communications devices and non- NES communications devices. However, in some embodiments, the infrastructure equipment may reserve the first PRACH resources for use exclusively by non-NES communications devices. In such embodiments, only NES communications devices use the additional PRACH resources and only non- NES communications devices use the first PRACH resources. This can improve communications efficiency by decreasing delay for communications devices to access the cell and decrease the probability of PRACH collisions.

[0154] Activation / Deactivation of additional PRACH resources

[0155] As mentioned previously, the indication of the additional PRACH resources and the control information including the conditions for using the additional PRACH resources may be transmitted via various DCI formats. However, when there are few NES communications devices in the cell which can utilise the additional PRACH resources, the benefit of improved communications efficiency by having the additional PRACH resources may be offset by the reduction in network energy savings caused by having the additional PRACH resources. In accordance with example embodiments, the additional PRACH resources may be activated or deactivated for use by NES communications devices to transmit PRACH. When the additional PRACH resources are activated, they can be used by NES communications devices to transmit PRACH. When the additional PRACH resources are deactivated, they cannot be used to transmit PRACH. The infrastructure equipment may transmit an activation indication or deactivation indication in the cell to indicate that the additional PRACH resources have been activated or deactivated for use by NES communications devices to transmit PRACH respectively.

[0156] The use of activation or deactivation indications can allow the infrastructure equipment to inform communications devices that the additional PRACH resources are activated or deactivated without having to reconfigure the additional PRACH resources every time they are required. In existing systems, any change to a PRACH resource configuration requires a system information update which takes a relatively long amount of time. Therefore, the use of activation and / or deactivation indications can provide a more efficient way of informing communications devices of which PRACH resources are available for use.

[0157] Group Common Downlink Control Information (GC DCI)

[0158] In some embodiments, the activation indication and / or deactivation indication may be transmitted in GC- DCI. This is particularly useful for communications devices in the idle or inactive mode. In some embodiments, a DCI format 1 0 with a System Information Radio Network Temporary Identifier (SI- RNTI) may comprise the activation and / or deactivation indication. In some embodiments, the activation and / or deactivation indication is provided by a reserved bit in the DCI format 1 0. Such embodiments can provide communications efficiency because they involve re-using existing signals for a different purpose.

[0159] In some embodiments, a new RNTI transmitted associated with the group common DCI by the infrastructure equipment provides the activation and / or deactivation indication.

[0160] Msg2 / MsgB

[0161] In some embodiments, the activation indication and / or deactivation indication may be transmitted in msg2 or msgB of a PRACH procedure. For example, the activation and / or deactivation indication may be transmitted in DCI format 1 0 with RA-RNTI / MsgB-RNTI or RAR / MsgB MAC. In some embodiments, the activation and / or deactivation indication may be indicated by a backoff indicator in msg2 or msgB. For example, the backoff indicator may indicate to the communications device that a PRACH collision has occurred and, in response, the communications device determines that the additional PRACH resources have been activated. In some embodiments, the communications device may implicitly determine that the additional PRACH resources have been deactivated if no response is received to a msg2 or msgB transmitted by the communications device. If no response is received from a PRACH transmission on the additional RACH resources, the NES communications device may select a PRACH resource from the first PRACH resources for transmitting its next PRACH. In this case, it is not necessary to execute power ramping for PRACH because this failure is not caused by low received power but by the infrastructure equipment sleeping during the additional PRACH resources since they are deactivated. The activation indication and / or deactivation indication via msg2 or msgB of a PRACH procedure may be transmitted in addition to an activation indication and / or deactivation indication via a broadcast message such as GC-DCI, Paging Message, and SIB1 without update notification. This may be beneficial especially if communications devices miss (i.e. do not receive) the activation and / or deactivation indication transmitted by the broadcast message before selecting PRACH resources for transmitting a PRACH or the infrastructure equipment changes the activation status of the additional PRACH resources between PRACH reception and RAR transmission.

[0162] Paging Message

[0163] In some embodiments, the activation and / or deactivation may be transmitted in a paging message. For example, the activation and / or deactivation indication may be comprised in DCI format 1 0 with Paging Radio Network Temporary Identifier (P-RNTI) by using a reserved bit, or a field of Short Message, or in a PDSCH scheduled by a paging DCI.

[0164] Connected Mode Communications Devices

[0165] In some embodiments, the activation and / or deactivation indication is transmitted in a Physical Downlink Control Channel (PDCCH) order to RACH, a Medium Access Control (MAC) Control Element (CE), or a radio resource control signal, or an LI signal (DCI). Such embodiments are particularly useful when the NES communications device is in connected mode.

[0166] Partitioning First / additional PRACH resources

[0167] In some embodiments, the infrastructure equipment may partition the first PRACH resources so that a portion of the first PRACH resources are reserved for NES communications devices and another portion of the first PRACH resources are reserved for non-NES communications devices. In some embodiments, the infrastructure equipment may partition the additional PRACH resources so that a portion of the first PRACH resources are reserved for some of the NES communications devices and another portion of the additional PRACH resources are reserved for other NES communications devices. This allows the network to partition the additional PRACH resources based on the usage / request / collision condition from NES capable UEs, or reserve part of the additional PRACH resource for certain type of UEs / services.

[0168] Conditions for using additional PRACH resources

[0169] Example embodiments will be described below regarding techniques of setting conditions for NES communications devices to determine whether they are allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources which are accessible to the NES communications devices and non-NES communications devices. 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. Through transmitting control information including conditions for using additional PRACH resources, the network can have finer control on which communications device(s) can use which part of the additional PRACH resources after activation, thereby improving the radio resource utilisation efficiency.

[0170] In accordance with example embodiments, the network transmits an indication of conditions, namely a threshold value, such that only communications devices encountering more than a predetermined number of RACH collisions can use the additional PRACH resources after activation.

[0171] In some example embodiments, the threshold value, such as the amount of RACH collisions, may be signalled via semi-static signalling, such as a configuration message, for configuring the additional PRACH resources. In some other embodiments, the threshold value may be included in DCI signalling for activating or deactivating additional PRACH resources.

[0172] In some example embodiments, where multiple DCI formats are supported to activate or deactivate additional PRACH resources, the adopted DCI format itself may indicate the threshold value. For example, DCI format 1 0 may be used to indicate a threshold value greater than 1, and DCI format 2 9 may be used to indicate a threshold value of 1. In this case, multiple RNTIs may be needed to be associated with each specific DCI format.

[0173] When transmitting DCI messages, the infrastructure equipment includes a unique RNTI in the messages in order to target the relevant DCI messages to specific communications devices, specific groups of communications devices, or specific processes to be performed by the communications devices, such as paging or random access processes. The communications devices in the cell then monitors the PDCCH for DCI messages that contain their desired RNTIs. In some example embodiments, different RNTIs may be mapped to different conditions (such as different threshold values) for the target communications devices to use the additional PRACH resources. In this way, the infrastructure equipment may implicitly assign and notify the conditions for using additional PRACH resources to target communications devices or a target group of communications devices. In some example embodiments, a dedicated RNTI may be introduced to indicate a pre-defined condition or threshold value. On the other hand, existing RNTIs, for example, P-RNTI, SI-RNTI, RA-RNTI, or C-RNTI, may be used to indicate different conditions or threshold values.

[0174] In a dynamic infrastructure equipment environment, PRACH resources and additional PRACH resources are shared among multiple communications devices. In the meantime, NES communications devices need to cycle between sleep and active states frequently in order to conserve power and reduce energy consumption. Even with the support from additional PRACH resources, there may still be insufficient resources for all communications devices in the cell to perform the RACH process, especially during high traffic periods. The resulting network congestion will cause delays for communications devices that are trying to access the network. By setting conditions such as collision threshold to limit the number of communications devices to access the activated additional PRACH resources, the network is able to dynamically manage the additional PRACH resources and prioritize allocation based on the situation and needs of the communications devices, particular those which have experienced more failed access attempts.

[0175] For example, in locations with weak signal strength or poor network coverage, PRACH resource allocation becomes more difficult. Communications devices may need to ramp up their transmission power during PRACH transmission attempts in order to successfully access the network, which directly impacts energy consumption. By adjusting the collision threshold to a lower value for these communications devices, the network is able to strategically allocate additional PRACH resources to tailor for the needs of these communications devices, allowing them to reduce the energy consumption during the RACH process.

[0176] In accordance with example embodiments, the infrastructure equipment may indicate conditions such that only those communications devices that initiate a predetermined service are allowed to perform RACH processes, such as handover, on additional PRACH resources. As an example, the predetermined service may be a service related to ultra-reliable low-latency communication (URLLC), enhanced mobile broadband (eMBB), or massive machine-type communication (mMTC).

[0177] In some example embodiments, the indication of conditions may contain a service list and such indication of conditions may be included in a configuration message for the additional PRACH resources.

[0178] In some other example embodiments, initial access may be performed on legacy PRACH resources for all types of communications devices, including non-NES communications devices and NES capable communications devices supporting additional PRACH resources capability. Meanwhile, additional RACH resources are used for other types of RACH (apart from initial access) only by NES capable communications devices.

[0179] As NR technology supports a variety of services, including enhanced mobile broadband (eMBB), ultrareliable low-latency communication (URLLC), and massive machine-type communication (mMTC), each of these services has different PRACH resource requirements and energy-saving needs. By setting the conditions for accessing additional PRACH resources based on the types of services initiated by the communications devices, the network is enabled to allocate PRACH resources efficiently and flexibly for different service types while maintaining energy-saving capabilities. As a result, adaptive resource allocation strategy can be implemented to ensure that each service type of communications devices is entitled to the necessary additional PRACH resources.

[0180] In accordance with example embodiments, the infrastructure equipment may provide an indication of conditions to the communications devices in a group concerning whether the communications devices are allowed to use additional PRACH resources, and accordingly the group of communications devices are required to monitor the additional PRACH resources activation / deactivation.

[0181] In some example embodiments, communications devices may be grouped based on a pre-defined communications device ID. In some other embodiments communications devices may be grouped based on network implementation, for example, belonging to the same service based group, or location based group. Infrastructure equipment may broadcast grouping information to the cell, such as a group ID, or a list of communications device IDs, etc. In some example embodiments, a new RNTI may be associated with the additional PRACH resource activation / deactivation DCI. In some other embodiments, the DCI may contain an indication of a group ID, to indicate which group of communications devices are allowed to use the additional PRACH resources after activation.

[0182] In some example embodiments, the indication of conditions concerning group ID may be associated with a subset of the additional PRACH resources. Based on information of the group ID, a communications device will know which subset of the additional PRACH resources are activated for the specific group of communications devices. As such, the radio resource utilisation ratio can be further optimized.

[0183] Through defining a condition for using additional PRACH resources based on the group to which the communications devices belong, the network is able to implement a flexible scheme for allocating additional PRACH resources to a particular group of communications devices in accordance with their requirements and priorities.

[0184] In accordance with example embodiments, the infrastructure equipment may provide an indication of conditions specifying that legacy communications devices shall use legacy PRACH resources whereas communications devices (such as Rel-19 UEs) supporting NES feature shall always use additional PRACH resources.

[0185] This condition of using additional PRACH resources is based on communications devices capability. Since the network is not always aware of the capability of the communications devices before RACH procedure is triggered (e.g. for CBRA), the arrangement allows the communications device itself to use the optimal resources based on its capability.

[0186] One of the targets of Network Energy Saving communications devices is to minimize energy consumption by reducing the time in active states, for example, RRC connected state. However, the allocation of additional PRACH resource requires the communications devices to wake up from the idle state or inactive state, and listen to the network for additional PRACH slots that are available. The need to wake up frequently to check for availability of the additional PRACH resources may lead to increased energy consumption. On the other hand, waiting too long for resource allocation may cause increased access delay, affecting service quality. By defining a condition for using the additional PRACH resources based on NES capability, the network is able to address the needs of communications devices supporting NES feature, so as to achieve the goals of energy savings and low access latency.

[0187] In accordance with example embodiments, the infrastructure equipment may provide an indication of the condition that additional RACH resources are only used for contention free random access (CFRA). In this case, the infrastructure equipment provides a reserved preamble from additional resources to a communications device based on whether the communications device is to perform CFRA. The arrangement is particularly advantageous for a scenario where legacy resources are sufficient to handle contention based random access (CBRA) requests.

[0188] In accordance with example embodiments, the infrastructure equipment may provide an indication of the condition for using additional PRACH resources based on a random number generated by a NES capable communications device. For example, if the random number generated is an odd number, the communications device is allowed to use additional resources for RACH process otherwise, it uses the first set of RACH resources. The arrangement provides the technical benefit of load balancing between legacy resources and additional resources in situations where there are more NES capable communications devices in the cell compared to legacy communications devices.

[0189] In accordance with example embodiments, the infrastructure equipment may provide an indication of a condition as to whether the NES communications devices are allowed to use additional PRACH resources or not next time when the communications devices perform RACH. In some example embodiments, the indication of the condition may be provided via DCI. In some other embodiments, the infrastructure equipment may send dedicated signalling, for example, a RRC release message, to the communications devices to indicate the condition. A communications device may comprise a register for storing the indication from the infrastructure equipment. As such, when the next RACH process is performed, the communications device may read the register / stored information and determine to use the additional PRACH resources if the condition of receiving a preceding indication from the infrastructure equipment is satisfied. The arrangement is particularly advantageous for communications devices located in areas with weak signal strength or poor network coverage where legacy PRACH resource allocation becomes difficult. By allocating the additional PRACH resources for the next RACH process, it can be avoided that the communications devices increase their transmission power to access the network which directly impacts energy consumption, hence undermining their energy-saving mechanisms.

[0190] Methods of operating communications devices and infrastructure equipment in accordance with example embodiments

[0191] Figure 10 is a flow diagram illustrating a method of operating infrastructure equipment of a wireless communications network providing a cell for communicating with one or more communications devices in the cell in accordance with example embodiments. The method starts in step SI.

[0192] In step S2, the method comprises transmitting an indication of additional physical random access channel (PRACH) resources reserved for use by the communications devices to transmit PRACH preamble during a RACH procedure. In some embodiments, the method comprises transmitting an indication of additional PRACH resources reserved for use by network energy saving (NES) communications devices to transmit PRACH preamble during a RACH procedure.

[0193] In step S3, the method comprises transmitting control information comprising conditions for the communications devices to determine whether the communications devices are allowed to use at least a part of the additional PRACH resources to perform a random access channel (RACH) procedure, or transmit PRACH preambles according to a RACH procedure in existing PRACH resources which are accessible to both the NES communications device and non-NES communications devices. In some embodiments, the method comprises transmitting control information comprising conditions for the NES communications devices to determine whether the NES communications devices are allowed to use at least a part of the additional PRACH resources to perform a RACH procedure.

[0194] The method ends in step S4.

[0195] In some embodiments, the control information is a downlink control information (DCI) message.

[0196] In some embodiments, the conditions for using the additional PRACH resources may include a threshold value and the NES communications devices determine to use the additional PRACH resources to perform the RACH procedure when the number of RACH collisions is above the threshold value. The threshold value may be indicated by different DCI formats. In addition, a pre-defined threshold value may be indicated by a new Radio Network Temporary Identifier (RNTI), and a new threshold value may be indicated by an existing RNTI, such as Paging RNTI (P-RNTI), System Information RNTI (SI-RNTI), and C-RNTI (Cell RNTI).

[0197] In some embodiments, the conditions for using the additional PRACH resources may include a service list such that the additional PRACH resources is used only by network energy saving communications devices that initiate a service in the service list. The service list may be transmitted in a message for configuring the additional PRACH resources.

[0198] In some embodiments, the method may further comprise a step of broadcasting grouping information of NES communications devices that need to monitor for activation or deactivation of additional PRACH resources. The grouping information of NES communications devices is based on a pre-defined identification of the NES communications devices or network implementation of the NES communications devices. Furthermore, a new RNTI may be associated with a DCI for activating or deactivating the additional PRACH resources. In some embodiments, the conditions for using the additional PRACH resources may include a group identification for indicating the group of NES communications devices that can use the additional PRACH resources. The group identification may be associated with a subset of the additional PRACH resources, and the NES communications devices within the group monitor for activation or deactivation of the subset of the additional PRACH resources.

[0199] In some embodiments, the conditions for using the additional PRACH resources may include capability of the communications devices for supporting NES features; capability of the communications devices for contention free random access; or a condition based on a random number generated by the NES communications devices.

[0200] In some embodiments, the method may further comprise a step of transmitting dedicated signalling to the NES communications devices to indicate whether they are allowed to use at least a part of the additional PRACH resources next time when the NES communications devices perform RACH. The dedicated signalling may be a Radio Resource Control (RRC) release message, which indicates that the NES communications devices should release an active connection.

[0201] In some embodiments, the indication of the additional PRACH resources and the control information comprising conditions for the NES communications devices to determine whether they are allowed to use at least a part of the additional PRACH resources are transmitted in the same DCI. Therefore, in some embodiments, steps S2 and S3 are referring to the same transmission and may therefore be regarded as one step. However, in other embodiments, steps S2 and S3 are referring to different transmissions. For example, the indication of the additional PRACH resources reserved for use by NES communications devices in the cell to transmit PRACH may be transmitted in a DCI different to the DCI that includes control information comprising the conditions. Therefore, in Figure 10 steps S2 and S3 are shown as separate steps for ease of explanation only.

[0202] Figure 11 is a flow diagram illustrating a method of operating a network energy saving (NES) communications device for communicating with an infrastructure equipment of a wireless communications network when the NES communications device is in a cell provided by the infrastructure equipment. The method starts in step Si l.

[0203] In step S 12, the method comprises receiving transmitting an indication of additional physical random access channel (PRACH) resources reserved for use by the communications devices to transmit PRACH preamble during a RACH procedure. In some embodiments, the communications device is a NES communications device, and the method comprises transmitting an indication of the additional PRACH resources reserved for use by network energy saving (NES) communications devices to transmit PRACH preamble during a RACH procedure.

[0204] In step SI 3, the method comprises receiving control information including conditions for the communications device to determine whether it is allowed to use at least a part of the additional PRACH resources to perform a random access channel (RACH) procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources which are accessible to both the NES communications device and non-NES communications devices. In some embodiments, the communications device is a NES communications device, and the control information comprises at least one condition for the NES communications device to determine whether the communications device is allowed to use at least a part of the additional PRACH resources to perform a RACH procedure.

[0205] The method ends in step S14. In some embodiments, the control information is a downlink control information (DCI) message.

[0206] In some embodiments, the conditions for using the additional PRACH resources may include a threshold value and the NES communications devices determine to use the additional PRACH resources to perform the RACH procedure when the number of RACH collisions is above the threshold value. The threshold value may be indicated by different DCI formats.

[0207] In some embodiments, the method may further comprise a step of receiving broadcast grouping information of NES communications devices that need to monitor for activation or deactivation of additional PRACH resources.

[0208] In some embodiments, the method may further comprise a step of receiving dedicated signalling to the NES communications device to indicate whether it is allowed to use at least a part of the additional PRACH resources next time when the NES communications device performs RACH. The dedicated signalling may be a Radio Resource Control (RRC) release message.

[0209] In some embodiments, the indication of the additional PRACH resources and the control information comprising conditions for the NES communications devices to determine whether they are allowed to use at least a part of the additional PRACH resources may be received in the same DCI. Therefore, in some embodiments, steps S2 and S3 are referring to the same transmission and may therefore be regarded as one step. However, in other embodiments, steps S2 and S3 are referring to different transmissions. For example, the indication of the additional PRACH resources reserved for use by the NES communications device to transmit PRACH may be received in a DCI different to the DCI that includes control information comprising the conditions. Therefore, in Figure 11 steps S2 and S3 are shown as separate steps for ease of explanation only.

[0210] As will be appreciated by a person skilled in the art, the relative order of the steps in Figure 10 and Figure 11 may be interchanged in any logical order.

[0211] Those skilled in the art would further appreciate that such infrastructure equipment and / or communications devices as herein defined may be further defined in accordance with the various arrangements and embodiments discussed in the preceding paragraphs. It would be further appreciated by those skilled in the art that such infrastructure equipment and communications devices as herein defined and described may form part of communications systems other than those defined by the present disclosure.

[0212] The following numbered paragraphs provide further example aspects and features of the present technique:

[0213] Paragraph 1. A method of operating infrastructure equipment of a wireless communications network for communicating with one or more communications devices, the method comprising transmitting an indication of additional physical random access channel (PRACH) resources reserved for use by the communications devices to transmit PRACH preamble during a random access channel (RACH) procedure, transmitting control information comprising at least one condition for the communications devices to determine whether the communications devices are allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources. Paragraph 2. A method according to paragraph 1, wherein the indication is an indication of the additional PRACH resources reserved for use by network energy saving (NES) communications devices to transmit PRACH preamble during a RACH procedure, and the control information comprises at least one condition for the NES communications devices to determine whether the NES communications devices are allowed to use at least a part of the additional PRACH resources to perform a RACH procedure.

[0214] Paragraph 3. A method according to paragraph 1 or 2, wherein the control information is a downlink control information (DCI) message.

[0215] Paragraph 4. A method according to any of paragraphs 1 to 3, wherein the at least one condition for using the additional PRACH resources, transmitted to the NES communications devices, includes a threshold value, each NES communications device using the additional PRACH resources to perform the RACH procedure when the relevant NES communications device determines that a number of RACH collisions is above the threshold value.

[0216] Paragraph 5. A method according to paragraph 4, wherein the threshold value is one of a plurality of threshold values indicated by one of a plurality of different DCI formats.

[0217] Paragraph 6. A method according to paragraph 4, wherein the threshold value is one of a plurality of threshold values indicated by one of a plurality of Radio Network Temporary Identifiers (RNTIs) associated with one of the plurality of different DCI formats.

[0218] Paragraph 7. A method according to paragraph 6, wherein the plurality of RNTIs comprise a dedicated RNTI, an existing RNTI including Paging RNTI (P-RNTI), System Information RNTI (SI-RNTI), and C- RNTI (Cell RNTI).

[0219] Paragraph 8. A method according to any of paragraphs 1 to 7, wherein the at least one condition for using the additional PRACH resources includes a service list such that the additional PRACH resources is used only by NES communications devices that initiate a service in the service list.

[0220] Paragraph 9. A method according to paragraph 8, wherein the service list is transmitted in a message for configuring the additional PRACH resources.

[0221] Paragraph 10. A method according to any of paragraphs 1 to 9, comprising broadcasting grouping information of NES communications devices , wherein these NES communications devices need to monitor for activation or deactivation of additional PRACH resources.

[0222] Paragraph 11. A method according to paragraph 10, wherein the grouping information of NES communications devices is based on a pre-defined identification of the NES communications devices or network implementation of the NES communications devices.

[0223] Paragraph 12. A method according to paragraph 10, wherein a RNTI is associated with a DCI for activating or deactivating the additional PRACH resources.

[0224] Paragraph 13. A method according to any of paragraphs 1 to 12, wherein the at least one condition for using the additional PRACH resources includes a group identification for indicating the group of NES communications devices that can use the additional PRACH resources.

[0225] Paragraph 14. A method according to paragraph 13, wherein the group identification is associated with a subset of the additional PRACH resources, the NES communications devices within the group being configured to monitor for activation or deactivation of the subset of the additional PRACH resources.

[0226] Paragraph 15. A method according to any of paragraphs 1 to 14, wherein the at least one condition for using the additional PRACH resources includes a capability of the communications devices for supporting NES features.

[0227] Paragraph 16. A method according to any of paragraphs 1 to 15, wherein the at least one condition for using the additional PRACH resources includes whether the communications devices are to perform contention free random access.

[0228] Paragraph 17. A method according to any of paragraphs 1 to 16, wherein the at least one condition for using the additional PRACH resources includes a condition based on a random number generated by the NES communications devices. Paragraph 18. A method according to any of paragraphs 1 to 17, comprising transmitting dedicated signalling to the NES communications devices to indicate whether they are allowed to use at least a part of the additional PRACH resources to perform RACH procedure.

[0229] Paragraph 19. A method according to paragraph 18, wherein the dedicated signalling is a Radio Resource Control (RRC) release message, which indicates that the NES communications devices should release an active connection.

[0230] Paragraph 20. A method according to any of paragraphs 1 to 19, comprising transmitting an indication to activate the additional PRACH resources in response to the infrastructure equipment detecting a collision between PRACHs at the infrastructure equipment.

[0231] Paragraph 21. A method according to paragraph 20, wherein the infrastructure equipment detects collisions between PRACHs when energy within a RACH occasion (RO) exceeds a threshold but cannot isolate a preamble sequence

[0232] Paragraph 22. A method according to paragraph 20, wherein the infrastructure equipment detects collisions between PRACHs when a preamble detection correlator of the infrastructure equipment shows more than a predefined number of distinct peaks.

[0233] Paragraph 23. A method according to any of paragraphs 1 to 22, comprising transmitting an indication to activate the additional PRACH resources in response to the infrastructure equipment detecting that an estimate of the number of NES communications devices in the cell exceeds a predefined threshold.

[0234] Paragraph 24. A method according to paragraph 23, wherein the infrastructure equipment estimates the number of NES communications devices in the cell by keeping a record of the communications devices reporting NES capability and comparing the count of the communications devices against a predefined threshold.

[0235] Paragraph 25. A method according to paragraph 23, wherein the infrastructure equipment estimates the number of NES communications devices in the cell based on the frequency of on-demand SIB1 requests being received by the infrastructure equipment.

[0236] Paragraph 26. A method of operating a communications device for communicating with an infrastructure equipment of a wireless communications network, the method comprising receiving an indication of additional physical random access channel (PRACH) resources reserved for use by the communications device to transmit PRACH preamble during a random access channel (RACH) procedure, receiving control information comprising at least one condition for the communications device to determine whether the communications device is allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

[0237] Paragraph 27. A method according to paragraph 26, the communications device is a network energy saving (NES) communications device, the indication is an indication of the additional PRACH resources reserved for use by the NES communications device to transmit PRACH preamble during a RACH procedure, and the control information comprises at least one condition for the NES communications device to determine whether the NES communications device is allowed to use at least a part of the additional PRACH resources to perform a RACH procedure.

[0238] Paragraph 28. A method according to paragraph 26, wherein the control information is a downlink control information (DCI) message.

[0239] Paragraph 29. A method according to any of paragraphs 26 to 28, wherein the at least one condition for using the additional PRACH resources, received by the NES communications device, includes a threshold value, the NES communications device uses the additional PRACH resources to perform the RACH procedure when the NES communications device determines that a number of RACH collisions is above the threshold value.

[0240] Paragraph 30. A method according to paragraph 29, wherein the threshold value is one of a plurality of threshold values indicated by one of a plurality of different DCI formats. Paragraph 31. A method according to paragraph 29, wherein the threshold value is one of a plurality of threshold values indicated by one of a plurality of Radio Network Temporary Identifier (RNTIs) associated with one of the plurality of different DCI formats.

[0241] Paragraph 32. A method according to paragraph 31, wherein the plurality of RNTIs comprise a dedicated RNTI, an existing RNTI including Paging RNTI (P-RNTI), System Information RNTI (SI- RNTI), and C-RNTI (Cell RNTI).

[0242] Paragraph 33. A method according to any of paragraphs 26 to 32, wherein the at least one condition for using the additional PRACH resources includes a service list such that the additional PRACH resources is used only by the NES communications device when it initiates a service in the service list.

[0243] Paragraph 34. A method according to paragraph 33, wherein the service list is received in a message for configuring the additional PRACH resources.

[0244] Paragraph 35. A method according to any of paragraphs 26 to 34, comprising receiving broadcast grouping information of NES communications devices , wherein these NES communications devices need to monitor for activation or deactivation of additional PRACH resources.

[0245] Paragraph 36. A method according to paragraph 35, wherein the grouping information of NES communications devices is based on a pre-defined identification of the NES communications devices or network implementation of the NES communications devices.

[0246] Paragraph 37. A method according to paragraph 35, wherein a RNTI is associated with a DCI for activating or deactivating the additional PRACH resources.

[0247] Paragraph 38. A method according to any of paragraphs 26 to 37, wherein the at least one condition for using the additional PRACH resources includes a group identification for indicating the group of NES communications devices that can use the additional PRACH resources.

[0248] Paragraph 39. A method according to paragraph 38, wherein the group identification is associated with a subset of the additional PRACH resources, the NES communications device within the group being configured to monitor for activation or deactivation of the subset of the additional PRACH resources. Paragraph 40. A method according to any of paragraphs 26 to 39, wherein the at least one condition for using the additional PRACH resources includes a capability of the communications device for supporting NES features.

[0249] Paragraph 41. A method according to any of paragraphs 26 to 40, wherein the at least one condition for using the additional PRACH resources includes whether the communications devices are to perform contention free random access.

[0250] Paragraph 42. A method according to any of paragraphs 26 to 41, wherein the at least one condition for using the additional PRACH resources includes a condition based on a random number generated by the NES communications device.

[0251] Paragraph 43. A method according to any of paragraphs 26 to 42, comprising receiving dedicated signalling from the infrastructure device which indicate whether the communications device is allowed to use at least a part of the additional PRACH resources to perform RACH procedure.

[0252] Paragraph 44. A method according to paragraph 43, wherein the dedicated signalling is a Radio Resource Control (RRC) release message, which indicates that the NES communications device should release an active connection.

[0253] Paragraph 45. Infrastructure equipment of a wireless communications network for communicating with one or more communications devices, the infrastructure equipment comprising a transceiver configured to transmit signals and to receive signals, and a controller configured in combination with the transceiver to transmit an indication of additional physical random access channel (PRACH) resources reserved for use by the communications devices to transmit PRACH preamble during a random access channel (RACH) procedure, transmit control information comprising at least one condition for the communications devices to determine whether the communications devices are allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

[0254] Paragraph 46. A communications device for communicating with infrastructure equipment of a wireless communications network, the NES communications device comprising a transceiver configured to transmit signals and to receive signals, and a controller configured in combination with the transceiver to receive an indication of additional physical random access channel (PRACH) resources reserved for use by the communications device to transmit PRACH preamble during a random access channel (RACH) procedure, receive control information comprising at least one condition for the communications device to determine whether the communications device is allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

[0255] Paragraph 47. Circuitry for Infrastructure equipment of a wireless communications network providing a cell for communicating with one or more communications devices in the cell, the circuitry comprising transceiver circuitry configured to transmit signals and to receive signals, and controller circuitry configured in combination with the transceiver circuitry to transmit an indication of additional physical random access channel (PRACH) resources reserved for use by the communications devices to transmit PRACH preamble during a random access channel (RACH) procedure, transmit control information comprising at least one condition for the communications devices to determine whether the communications devices are allowed to use at least a part of the additional PRACH resources to perform a random access channel (RACH) procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

[0256] Paragraph 48. Circuity for a communications device for communicating with infrastructure equipment of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals and to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive an indication of additional physical random access channel (PRACH) resources reserved for use by the communications device to transmit PRACH during a random access channel (RACH) procedure, receive control information comprising at least one condition for the communications device to determine whether the communications device is allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

[0257] Paragraph 49. A wireless communications system comprising an infrastructure equipment according to paragraph 45 and a communications device according to paragraph 46.

[0258] Paragraph 50. A computer program which, when the program is executed by a computer, cause the computer to perform the method of paragraph 1 or paragraph 26.

[0259] Paragraph 51. A non-transitory computer-readable storage medium storing a computer program according to paragraph 50.

[0260] 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.

[0261] 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.

[0262] 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.

[0263] References

[0264] [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[0265] [2] TR 38.913, “Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14)”, 3rd Generation Partnership Project, vl4.3.0, August 2017.

[0266] [3] TS 38.470, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Fl general aspects and principles (Release 17)”, 3GPP, V17.4.0, March 2023.

[0267] [4] TS 38.473, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Fl application protocol (F1AP) (Release 17)”, 3GPP, V17.4.1, April 2023.

[0268] [5] TS 38.401, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Architecture description (Release 17)”, 3GPP, V17.4.0, March 2023.

[0269] [6] RP -241650, “Revised WID: Enhancements of network energy savings for NR,” 3GPP TSG RAN Meeting# 104, Shanghai, China, June 17-20, 2024

[0270] [7] GSMA, 5G energy efficiencies: Green is the new black, https: / / data.gsmaintelligence.com / api- web / v2 / research-file-download?id=54165956&file=241120-5G-energy.pdf

[0271] [8] TR 38.864, “Study on network energy savings for NR”, 3GPP, V18.1.0, March 2023.

Claims

CLAIMSWhat is claimed is:

1. A method of operating infrastructure equipment of a wireless communications network for communicating with one or more communications devices, the method comprising transmitting an indication of additional physical random access channel (PRACH) resources reserved for use by the communications devices to transmit PRACH preamble during a random access channel (RACH) procedure, transmitting control information comprising at least one condition for the communications devices to determine whether the communications devices are allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

2. A method according to claim 1, wherein the indication is an indication of the additional PRACH resources reserved for use by network energy saving (NES) communications devices to transmit PRACH preamble during a RACH procedure, and the control information comprises at least one condition for the NES communications devices to determine whether the NES communications devices are allowed to use at least a part of the additional PRACH resources to perform a RACH procedure.

3. A method according to claim 1, wherein the control information is a downlink control information (DCI) message.

4. A method according to claim 1, wherein the at least one condition for using the additional PRACH resources, transmitted to the NES communications devices, includes a threshold value, each NES communications device using the additional PRACH resources to perform the RACH procedure when the relevant NES communications device determines that a number of RACH collisions is above the threshold value.

5. A method according to claim 4, wherein the threshold value is one of a plurality of threshold values indicated by one of a plurality of different DCI formats.

6. A method according to claim 4, wherein the threshold value is one of a plurality of threshold values indicated by one of a plurality of Radio Network Temporary Identifiers (RNTIs) associated with one of the plurality of different DCI formats.

7. A method according to claim 6, wherein the plurality of RNTIs comprise a dedicated RNTI, an existing RNTI including Paging RNTI (P-RNTI), System Information RNTI (SI-RNTI), and C-RNTI (Cell RNTI).

8. A method according to claim 1, wherein the at least one condition for using the additional PRACH resources includes a service list such that the additional PRACH resources is used only by NES communications devices that initiate a service in the service list.

9. A method according to claim 8, wherein the service list is transmitted in a message for configuring the additional PRACH resources.

10. A method according to claim 1, comprising broadcasting grouping information of NES communications devices , wherein these NES communications devices need to monitor for activation or deactivation of additional PRACH resources.

11. A method according to claim 10, wherein the grouping information of NES communications devices is based on a pre-defined identification of the NES communications devices or network implementation of the NES communications devices.

12. A method according to claim 10, wherein a RNTI is associated with a DCI for activating or deactivating the additional PRACH resources.

13. A method according to claim 1, wherein the at least one condition for using the additional PRACH resources includes a group identification for indicating the group of NES communications devices that can use the additional PRACH resources.

14. A method according to claim 13, wherein the group identification is associated with a subset of the additional PRACH resources, the NES communications devices within the group being configured to monitor for activation or deactivation of the subset of the additional PRACH resources.

15. A method according to claim 1, wherein the at least one condition for using the additional PRACH resources includes a capability of the communications devices for supporting NES features.

16. A method according to claim 1, wherein the at least one condition for using the additional PRACH resources includes whether the communications devices are to perform contention free random access.

17. A method according to claim 1, wherein the at least one condition for using the additional PRACH resources includes a condition based on a random number generated by the NES communications devices.

18. A method according to claim 1, comprising transmitting dedicated signalling to the NES communications devices to indicate whether they are allowed to use at least a part of the additional PRACH resources to perform RACH procedure.

19. A method according to claim 18, wherein the dedicated signalling is a Radio Resource Control (RRC) release message, which indicates that the NES communications devices should release an active connection.

20. A method according to claim 1, comprising transmitting an indication to activate the additional PRACH resources in response to the infrastructure equipment detecting a collision between PRACHs at the infrastructure equipment.

21. A method according to claim 20, wherein the infrastructure equipment detects collisions between PRACHs when energy within a RACH occasion (RO) exceeds a threshold but cannot isolate a preamble sequence22. A method according to claim 20, wherein the infrastructure equipment detects collisions between PRACHs when a preamble detection correlator of the infrastructure equipment shows more than a predefined number of distinct peaks.

23. A method according to claim 1, comprising transmitting an indication to activate the additional PRACH resources in response to the infrastructure equipment detecting that an estimate of the number of NES communications devices in the cell exceeds a predefined threshold.

24. A method according to claim 23, wherein the infrastructure equipment estimates the number of NES communications devices in the cell by keeping a record of the communications devices reporting NES capability and comparing the count of the communications devices against a predefined threshold.

25. A method according to claim 23, wherein the infrastructure equipment estimates the number of NES communications devices in the cell based on the frequency of on-demand SIB1 requests being received by the infrastructure equipment.

26. A method of operating a communications device for communicating with an infrastructure equipment of a wireless communications network, the method comprising receiving an indication of additional physical random access channel (PRACH) resources reserved for use by the communications device to transmit PRACH preamble during a random access channel (RACH) procedure, receiving control information comprising at least one condition for the communications device to determine whether the communications device is allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

27. A method according to claim 26, the communications device is a network energy saving (NES) communications device, the indication is an indication of the additional PRACH resources reserved for use by the NES communications device to transmit PRACH preamble during a RACH procedure, and the control information comprises at least one condition for the NES communications device to determine whether the NES communications device is allowed to use at least a part of the additional PRACH resources to perform a RACH procedure.

28. A method according to claim 26, wherein the control information is a downlink control information (DCI) message.

29. A method according to claim 26, wherein the at least one condition for using the additional PRACH resources, received by the NES communications device, includes a threshold value, the NES communications device uses the additional PRACH resources to perform the RACH procedure when the NES communications device determines that a number of RACH collisions is above the threshold value.

30. A method according to claim 29, wherein the threshold value is one of a plurality of threshold values indicated by one of a plurality of different DCI formats.

31. A method according to claim 29, wherein the threshold value is one of a plurality of threshold values indicated by one of a plurality of Radio Network Temporary Identifier (RNTIs) associated with one of the plurality of different DCI formats.

32. A method according to claim 31, wherein the plurality of RNTIs comprise a dedicated RNTI, an existing RNTI including Paging RNTI (P-RNTI), System Information RNTI (SI-RNTI), and C-RNTI (Cell RNTI).

33. A method according to claim 26, wherein the at least one condition for using the additional PRACH resources includes a service list such that the additional PRACH resources is used only by the NES communications device when it initiates a service in the service list.

34. A method according to claim 33, wherein the service list is received in a message for configuring the additional PRACH resources.

35. A method according to claim 26, comprising receiving broadcast grouping information of NES communications devices , wherein these NES communications devices need to monitor for activation or deactivation of additional PRACH resources.

36. A method according to claim 35, wherein the grouping information of NES communications devices is based on a pre-defined identification of the NES communications devices or network implementation of the NES communications devices.

37. A method according to claim 35, wherein a RNTI is associated with a DCI for activating or deactivating the additional PRACH resources.

38. A method according to claim 26, wherein the at least one condition for using the additional PRACH resources includes a group identification for indicating the group of NES communications devices that can use the additional PRACH resources.

39. A method according to claim 38, wherein the group identification is associated with a subset of the additional PRACH resources, the NES communications device within the group being configured to monitor for activation or deactivation of the subset of the additional PRACH resources.

40. A method according to claim 26, wherein the at least one condition for using the additional PRACH resources includes a capability of the communications device for supporting NES features.

41. A method according to claim 26, wherein the at least one condition for using the additional PRACH resources includes whether the communications devices are to perform contention free random access.

42. A method according to claim 26, wherein the at least one condition for using the additional PRACH resources includes a condition based on a random number generated by the NES communications device.

43. A method according to claim 26, comprising receiving dedicated signalling from the infrastructure device which indicate whether the communications device is allowed to use at least a part of the additional PRACH resources to perform RACH procedure.

44. A method according to claim 43, wherein the dedicated signalling is a Radio Resource Control (RRC) release message, which indicates that the NES communications device should release an active connection.

45. Infrastructure equipment of a wireless communications network for communicating with one or more communications devices, the infrastructure equipment comprising a transceiver configured to transmit signals and to receive signals, and a controller configured in combination with the transceiver to transmit an indication of additional physical random access channel (PRACH) resources reserved for use by the communications devices to transmit PRACH preamble during a random access channel (RACH) procedure,transmit control information comprising at least one condition for the communications devices to determine whether the communications devices are allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

46. A communications device for communicating with infrastructure equipment of a wireless communications network, the NES communications device comprising a transceiver configured to transmit signals and to receive signals, and a controller configured in combination with the transceiver to receive an indication of additional physical random access channel (PRACH) resources reserved for use by the communications device to transmit PRACH preamble during a random access channel (RACH) procedure, receive control information comprising at least one condition for the communications device to determine whether the communications device is allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

47. Circuitry for Infrastructure equipment of a wireless communications network providing a cell for communicating with one or more communications devices in the cell, the circuitry comprising transceiver circuitry configured to transmit signals and to receive signals, and controller circuitry configured in combination with the transceiver circuitry to transmit an indication of additional physical random access channel (PRACH) resources reserved for use by the communications devices to transmit PRACH preamble during a random access channel (RACH) procedure, transmit control information comprising at least one condition for the communications devices to determine whether the communications devices are allowed to use at least a part of the additional PRACH resources to perform a random access channel (RACH) procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

48. Circuity for a communications device for communicating with infrastructure equipment of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals and to receive signals, and controller circuitry configured in combination with the transceiver circuitry to receive an indication of additional physical random access channel (PRACH) resources reserved for use by the communications device to transmit PRACH during a random access channel (RACH) procedure, receive control information comprising at least one condition for the communications device to determine whether the communications device is allowed to use at least a part of the additional PRACH resources to perform a RACH procedure, or to transmit PRACH preambles according to a RACH procedure in existing PRACH resources.

49. A wireless communications system comprising an infrastructure equipment according to claim 45 and a communications device according to claim 46.

50. A computer program which, when the program is executed by a computer, cause the computer to perform the method of claim 1 or claim 26.

51. A non-transitory computer-readable storage medium storing a computer program according to claim 50.

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