Methods, communications devices, infrastructure equipment

Abstract

Methods, communications devices, infrastructure equipment, and circuitry for allowing a communications device to determine when to transmit an uplink transmission to an uplink-only reception point (URP). The communications device identifies a reference timing, based on which the communications device determines when the uplink transmission should be transmitted. The reference timing may be a transmission time of the uplink transmission or may be used to calculate a timing advance for the uplink transmission.

Description

[0001] METHODS, COMMUNICATIONS DEVICES, INFRASTRUCTURE EQUIPMENT

[0002] The present application claims the Paris Convention priority of European patent application EP23193594.1 , filed 25 August 2023, the contents of which are hereby incorporated by reference.

[0003] BACKGROUND

[0004] Field of Disclosure

[0005] The present disclosure relates to communications devices, infrastructure equipment of a wireless communications network and methods of operating communications devices and infrastructure equipment of a wireless communications network.

[0006] Description of Related Art

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

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

[0009] Wireless communications networks are expected to routinely and efficiently support communications with an ever-increasing range of devices associated with a wide range of data traffic profiles and types. For example, it is expected that wireless communications networks efficiently support communications with devices including reduced complexity devices, machine type communication (MTC) devices, high resolution video displays, virtual reality headsets 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 I 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). In view of this there is a desire for current generation wireless communications networks, for example those referred to as 5G or new radio (NR) systems I new radio access technology (RAT) systems, as well as future iterations I releases of existing systems, to efficiently support connectivity for a wide range of devices associated with different applications and different characteristic data traffic profiles and requirements.

[0010] 5G NR has continuously evolved and the current work plan includes 5G-NR-advanced in which some further enhancements are expected, especially to support new use- cases / scenarios with higher requirements. The desire to support these new use-cases and scenarios gives rise to new challenges for efficiently handling communications in wireless communications systems that need to be addressed.

[0011] SUMMARY OF THE DISCLOSURE

[0012] The present disclosure can help address or mitigate at least some of the issues discussed above.

[0013] Respective aspects and features of the present disclosure are defined in the appended claims.

[0014] 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.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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:

[0017] 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;

[0018] Figure 2 schematically represents some aspects of a new radio access technology (RAT) wireless telecommunications system which may be configured to operate in accordance with certain embodiments of the present disclosure;

[0019] 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;

[0020] Figure 4 schematically represents an example of a Heterogeneous Network (HetNet);

[0021] Figure 5 schematically represents an example of a HetNet including a plurality of uplink-only reception points (URPs);

[0022] Figure 6 schematically illustrates an example of conventional 4-step RACH;

[0023] Figure 7 schematically illustrates an example of conventional 2-step RACH;

[0024] Figure 8 illustrates an example of a MAC CE for adjusting the timing advance applied by a UE.

[0025] Figure 9 illustrates an example arrangement for determining timing advances in a HetNet. Figure 10 illustrates an example arrangement for determining timing advances in a HetNet including one or more URPs.

[0026] Figure 11 is a method of operating a communications device in accordance with example embodiments;

[0027] Figure 12 is a method of operating a communications device in accordance with example embodiments;

[0028] Figure 13 is an example of a heterogeneous network

[0029] Figure 14 schematically illustrates slot timing relations between the macro-TRP, UE and URP of Figure 13.

[0030] Figure 15 illustrates an example method for a communications device according to an example of the present disclosure.

[0031] Figure 16 illustrates an example method for an uplink-only reception point (i.e. an uplink-only infrastructure equipment) according to an example of the present disclosure.

[0032] Figure 17 illustrates an example method for a transmission and reception point (i.e. an infrastructure equipment) according to an example of the present disclosure.

[0033] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] Long Term Evolution Advanced Radio Access Technology (4G)

[0035] 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.

[0036] The network 6 includes a plurality of base stations 1 connected to a core network 2. Each base station provides a coverage area 3 (i.e. a cell) within which data can be communicated to and from communications devices 4. Although each base station 1 is shown in Figure 1 as a single entity, the skilled person will appreciate that some of the functions of the base station may be carried out by disparate, inter-connected elements, such as antennas (or antennae), remote radio heads, amplifiers, etc. Collectively, one or more base stations may form a radio access network.

[0037] Data is transmitted from base stations 1 to communications devices or mobile terminals (MT) 4 within their respective coverage areas 3 via a radio downlink. Data is transmitted from communications devices 4 to the base stations 1 via a radio uplink. The core network 2 routes data to and from the communications devices 4 via the respective base stations 1 and provides functions such as authentication, mobility management, charging and so on. The communications or terminal devices 4 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.

[0038] Base stations, which are an example of network infrastructure equipment, may also be referred to as transceiver stations, nodeBs, e-nodeBs, eNB, g-nodeBs, gNB and so forth. In this regard different terminology is often associated with different generations of wireless telecommunications systems for elements providing broadly comparable functionality. However, certain embodiments of the disclosure may be equally implemented in different generations of wireless telecommunications systems, and for simplicity certain terminology may be used regardless of the underlying network architecture. That is to say, the use of a specific term in relation to certain example implementations is not intended to indicate these implementations are limited to a certain generation of network that may be most associated with that particular terminology.

[0039] New Radio Access Technology (5G (NR))

[0040] 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 (Dlls) 41 , 42 by a connection interface represented as a line 16. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within a radio frequency bandwidth available to the wireless communications network. Thus, within a range for performing radio communications via the wireless access interface, each of the TRPs 10, forms a cell of the wireless communications network as represented by a circle 12. As such, wireless communications devices 14 which are within a radio communications range provided by the cells 12 can transmit and receive signals to and from the TRPs 10 via the wireless access interface. Each of the distributed units 41 , 42 are connected to a central unit (CU) 40 (which may be referred to as a controlling node) via an interface 46. The central unit 40 is then connected to the core network 20 which may contain all other functions required to transmit data for communicating to and from the wireless communications devices and the core network 20 may be connected to other networks 30.

[0041] 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.

[0042] The TRPs 10 of Figure 2 may in part have a corresponding functionality to a base station or eNodeB of an LTE network. Similarly, the communications devices 14 may have a functionality corresponding to the UE devices 4 known for operation with an LTE network. It will be appreciated therefore that operational aspects of a new RAT network (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be different to those known from LTE or other known mobile telecommunications standards. However, it will also be appreciated that each of the core network component, base stations and communications devices of a new RAT network will be functionally similar to, respectively, the core network component, base stations and communications devices of an LTE wireless communications network. In terms of broad top-level functionality, the core network 20 connected to the new RAT telecommunications system represented in Figure 2 may be broadly considered to correspond with the core network 2 represented in Figure 1 , and the respective central units 40 and their associated distributed units I TRPs 10 may be broadly considered to provide functionality corresponding to the base stations 1 of Figure 1 . The term network infrastructure equipment I access node may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may lie with the controlling node I central unit and I or the distributed units I 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 I TRPs 10 associated with the first communication cell 12.

[0043] 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.

[0044] Thus, certain embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems I 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 I access nodes and a communications device, wherein the specific nature of the network infrastructure equipment I 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 I access node may comprise a base station, such as an LTE-type base station 1 as shown in Figure 1 which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment may comprise a control unit I 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.

[0045] 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 circuit 49, a receiver circuit 48 and a controller circuit 44 which is configured to control the transmitter circuit 49 and the receiver circuit 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 circuit 30 and received by the receiver circuit 48 in accordance with the conventional operation.

[0046] The transmitter circuits 30, 49 and the receiver circuits 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 controller circuits 34, 44 (as well as other controllers described in relation to examples and embodiments of the present disclosure) may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc., configured to carry out instructions which are stored on a computer readable medium, such as a non-volatile memory. The processing steps described herein may be carried out by, for example, a microprocessor in conjunction with a random access memory, operating according to instructions stored on a computer readable medium. The transmitters, the receivers and the controllers are schematically shown in Figure 3 as separate elements for ease of representation. However, it will be appreciated that the functionality of these elements can be provided in various different ways, for example using one or more suitably programmed programmable computer(s), or one or more suitably configured application-specific integrated circuit(s) I circuitry I chip(s) I chipset(s). As will be appreciated the infrastructure equipment I TRP I base station as well as the UE I communications device will in general comprise various other elements associated with its operating functionality.

[0047] 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.

[0048] The interface 46 between the DU 42 and the CU 40 is known as the F1 interface which can be a physical or a logical interface. The F1 interface 46 between CU and DU may operate in accordance with specifications 3GPP TS 38.470 and 3GPP TS 38.473, and may be formed from a fibre optic or other wired or wireless high bandwidth connection. In one example the connection 16 from the TRP 10 to the DU 42 is via fibre optic. The connection between a TRP 10 and the core network 20 can be generally referred to as a backhaul, which comprises the interface 16 from the network interface 50 of the TRP10 to the DU 42 and the F1 interface 46 from the DU 42 to the CU 40.

[0049] 5G / NR radio access technologies can provide various functionalities such as Massive Machine Type Communications (mMTC), enhanced Mobile Broadband (eMBB) and Ultra Reliable & Low Latency Communications (URLLC). mMTC are devices such as sensors that have low complexity and a large coverage density of 1 million devices per km2. eMBB services are characterised by high capacity with a requirement to support up to 20 Gb / s. Furthermore, URLLC requires a reliability of 1 - 10-5(99.999%) to 1 - 10-6(99.9999%) for one transmission of a 32-byte packet with a user plane latency of 1 ms.

[0050] 3GPP has already completed the first phase of 5G (known as 5G-NR) in Release-15, 16 and 17 of the 3GPP standards. In the first phase, 3GPP has specified features to bring about mMTC, eMBB, URLLC and other functionalities such as massive multiple-input multiple-output (MIMO), reduced complexity UEs and coverage enhancements.

[0051] 3GPP is now moving ahead with a second phase of 5G (known as 5G-NR-Advanced) in Release 18, 19 of the 3GPP standards, and beyond. One feature being proposed in the second phase is heterogeneous networks (HetNets) and, in particular, heterogeneous networks with uplink-only reception points (URPs).

[0052] Heterogeneous Network (HetNet)

[0053] In a 5G operation, a Heterogeneous Network (HetNet) may be deployed. A HetNet is a network comprising a plurality of TRPs including a TRP which provides a macro cell and one or more TRPs which provide a respective one or more small cells. A TRP which provides a macro cell may alternatively be referred to as a “macro gNB”. As will be known to one skilled in the art, a TRP providing a macro cell transmits with a higher power than a TRP providing a small cell. Therefore, a macro cell provides a larger coverage area for UEs than a small cell. As will be understood by a person skilled in the art, small cells are typically provided to alleviate a load on the TRP which provides the macro cell caused by uplink and downlink traffic. This is particularly advantageous when there is a large number of UEs present in the macro cell (referred to as “dense macro cell deployment”). Furthermore, TRPs providing small cells may be deployed near the edge of the macro cell to enhance coverage near the cell edge. An example of a HetNet is schematically illustrated in Figure 4.

[0054] As shown in Figure 4, a first TRP 402 provides a macro cell 404 for a first UE 424, a second UE 426, a third UE 428 and a fourth UE 430 located within the macro cell 404. Also shown is a second TRP 406 providing a small cell 408 for the first UE 424 which is located within the small cell 408 provided by the second TRP 406. Also shown is a third TRP 414 providing a small cell 416 for the third UE 428 which is located within the small cell 416 provided by the third TRP 414. The second UE 426 and the fourth UE 430 are located within the macro cell 404 but are not located within the small cell 408 provided by the second TRP 406 or the small cell 416 provided by the third TRP 414.

[0055] Although not shown in Figure 4, the second TRP 406 and the third TRP 414 may be connected to the first TRP 402 via wired backhaul connections such as fiber optic cables or wireless connections, thereby allowing communication between the first TRP 402 and the second TRP 406 and between the first TRP 402 and the third TRP 414. When the second TRP 406 and the third TRP 414 are connected to the first TRP 402, scheduling may be coordinated and multi-TRP MIMO may be provided.

[0056] A technical problem associated with HetNets is that UEs, particularly those near the edge of a small cell, may experience significant downlink interference from the TRP which provides the macro cell. For example, as shown in Figure 4, the first UE 424 is located near the edge of the small cell 408 provided by the second TRP 406. The first UE 424 is receiving a downlink transmission 420 from the second TRP 406. At the same time, the second UE 418 is receiving a downlink transmission 418 from the first TRP 402. Since the first UE 424 is near the edge of the small cell 408 provided by the second TRP 406, a power of the downlink transmission 420 from the second TRP 406 is likely to be lower than a power of the downlink transmission 418 from the first TRP 402 at the location of the first UE 424. Therefore, the downlink transmission 418 from the first TRP 402 causes significant interference 418a to the downlink transmission from the second TRP 406.

[0057] Similarly, UEs being served by the TRP providing the macro cell may experience significant downlink interference from UEs being served by a TRP providing a small cell. For example, as shown in Figure 4, the fourth UE 430 is located near the edge of the macro cell 404 provided by the first TRP 402. The fourth UE 430 is receiving a downlink transmission 432 from the first TRP 402. At the same time, the third UE 428 is receiving a downlink transmission 422 from the third TRP 414. Since the fourth UE 430 is near the edge of the macro cell 404 provided by the first TRP 402, a power of the downlink transmission 432 from the first TRP 402 is likely to be lower than a power of the downlink transmission 422 from the third TRP 414 at the location of the fourth UE 430. Therefore, the downlink transmission 422 from the third TRP 414 causes significant interference 422a to the downlink transmission 432 from the first TRP 402.

[0058] On the other hand, uplink interference may also be experienced in HetNet deployments. For example, interference may occur between an uplink transmission from a UE to a TRP providing a small cell and an uplink transmission from another UE to a TRP providing a macro cell, or another small cell. However, uplink interference can typically be reduced by one of the UEs reducing a transmission power of its uplink transmission. Uplink-only reception point (URP)

[0059] It has been observed that there is often a bottleneck of uplink traffic in dense macro cell deployments. The load caused by the uplink traffic on the TRP providing the macro cell can be alleviated by providing a HetNet deployment such as that described with reference to Figure 4. However, as described above, such networks can present significant problems due to downlink interference. Recognising this, it has been proposed to introduce uplink-only reception points (URP) in HetNets [2], URPs are configured to receive uplink transmissions from UEs but cannot transmit downlink transmissions to UEs. A URP may be connected to a TRP providing a macro cell via a wired backhaul connection, such as a fiber optic cable, thereby allowing communication between the URP and the TRP providing the macro cell. By deploying URPs in a HetNet, the load on the TRP providing the macro cell can be alleviated and the downlink interference which would otherwise be experienced, or caused, by TRPs providing small cells can be prevented. However, URPs are not able to alleviate the load on the TRP providing the macro cell caused by downlink transmissions. URPs deployed near the macro cell edge may increase the throughput of a UE being served by that URP because the UE may be close to the URP and therefore likely have better radio conditions with the URP compared to the TRP providing the macro cell. Furthermore, UEs near the macro cell edge may transmit uplink transmissions to the URP with a lower transmission power than a transmission power with which the UE transmits uplink transmissions to the TRP providing the macro cell, which results in reduced uplink interference. Furthermore, URPs can be low cost because they do not require a wireless transmitter for communicating downlink transmissions to UEs. URPs may also help replace dual connectivity (DC) and solve uplink problems such as traffic split ratio and power sharing in DC scenarios. Traffic split ratios and power sharing are typically semi statically configured in DC, but they may be dynamically configured if URPs are used.

[0060] An example of a HetNet which includes URPs is shown in Figure 5. As shown in Figure 5, a first TRP 502 provides a macro cell 504 for a first UE 534, a second UE 536, a third UE 538 and a fourth UE 540 located within the macro cell 504. Also shown is a first URP 506 providing a small cell 508 for the first UE 534 which is located within the small cell 508 provided by the first URP 506. Also shown is a second URP 510 providing a small cell 512 for the third UE 538 which is located within the small cell 512 provided by the second URP 510. Also shown is a second TRP 514 providing a small cell 516 for the fourth UE 540 which is located within the small cell 516 provided by the second TRP 514. The second UE 536 is located within the macro cell 504 but is not located within the small cell 508 provided by the first URP, the small cell 512 provided by the second URP 510 or the small cell 516 provided by the second TRP 514.

[0061] Since the first UE 534 is located within the macro cell 504 provided by the first TRP 502 and the small cell 508 provided by the first URP 506, then the first UE 534 is served by the first URP 506 for uplink transmissions 520 and is served by the first TRP 502 for downlink transmissions 518. In other words, the first UE 534 is able to transmit uplink transmissions 520 to the first URP 506 and receive downlink transmissions 518 from the first TRP 502.

[0062] Since the second UE 536 is within the macro cell 504 provided by the first TRP 502 but is not located within the small cell 508 provided by the first URP, the small cell 512 provided by the second URP 510 or the small cell 516 provided by the second TRP 514, then the second UE 536 is served by the first TRP 502 for uplink transmissions 522 and downlink transmissions 524. In other words, the second UE 536 is able to transmit uplink transmissions 522 to the first TRP 502 and receive downlink transmissions 524 from the first TRP 502. Since the third UE 538 is located within the macro cell 504 provided by the first TRP 502 and the small cell 512 provided by the second URP 510, then the third UE 538 is served by the second URP 510 for uplink transmissions 528 and is served by the first TRP 502 for downlink transmissions 526. In other words, the third UE 538 is able to transmit uplink transmissions 528 to the second URP 510 and receive downlink transmissions 526 from the first TRP 502.

[0063] Since the fourth UE 540 is located within the small cell 516 provided by the second TRP 514, then the fourth UE 540 is served by the second TRP 514 for uplink transmissions 532 and for downlink transmissions 530. In other words, the fourth UE 540 is able to transmit uplink transmissions 532 and receive downlink transmissions 530 from the second TRP 514.

[0064] Although not shown in Figure 5, the first URP 506, second URP 510 and second TRP 514 may be connected to the first TRP 502 via a wired backhaul connections, such as fiber optic cables, thereby allowing communication between the first URP 506, second URP 510, second TRP 514 and the first TRP 502

[0065] Determining Timing Advance (TA) during Initial Access

[0066] In existing wireless communications networks, a UE performs an initial access procedure with a gNB to transition from a Radio Resource Control (RRC) idle state, or RRC inactive state, to an RRC connected state. During initial access, the UE follows either a 4-step random access channel (RACH) procedure or a 2-step RACH procedure. A conventional 4-step RACH procedure is shown in Figure 6.

[0067] In a first step, a UE 602 transmits a physical random-access channel (PRACH) preamble to a gNB 604 (“Message 1”). Based on the received PRACH preamble, the gNB 604 estimates a propagation delay between the UE 602 and the gNB 604. The gNB 604 then converts the estimated propagation delay into a timing advance (TA) value.

[0068] In a second step, the gNB 604 transmits a random-access response (RAR) to the UE 602 using a Random Access Ratio Network Temporary Identifier (RA-RNTI) (“Message 2”). The RAR message comprises a detected index of the PRACH preamble, the TA value and a resource allocation for a physical uplink shared channel (PUSCH) transmission to be transmitted by the UE 602 (Message 3). The UE 602 adjusts its future uplink transmissions based on the TA value.

[0069] In a third step, the UE 602 transmits an identification of the UE 602 in the PUSCH transmission for which the resource allocation was received (“Message 3”).

[0070] In a fourth step, the gNB 604 transmits a contention-resolution message to the UE 602 comprising a confirmation of the identification of the UE 602 that is being connected to a cell provided by the gNB 604 (“Message 4”). This resolves contention if, for example, multiple UEs transmitted a PRACH preamble to the gNB 604 in the first step.

[0071] A conventional 2-step RACH procedure is shown in Figure 7.

[0072] In a first step, a UE 702 transmits msgA to a gNB 704. msgA comprises a PRACH preamble and a PUSCH which comprises data for the gNB 704. Based on msgA, the gNB 704 estimates a propagation delay between the UE 702 and the gNB 704. The gNB 704 then converts the estimated propagation delay into a timing advance (TA) value. Therefore, msgA is similar to Message 1 and Message 3 in 4-step RACH.

[0073] In a second step, the gNB 704 transmits msgB to the UE 702 using a msgB-RNTI. msgB comprises responses to one or more UEs. In case msgA was successful for a given UE, msgB comprises at least a contention resolution identity (ID), a cell Radio Network Temporary Identifier (C-RNTI) and the TA value. Therefore, msgB is similar to Message 2 and 4 in 4-step RACH. The UE adjusts its future uplink transmissions based on the TA value.

[0074] For both 4-step and 2-step RACH, the TA value (denoted as TA) is a value in the following sequence: 0,1 , 2, 3... ,3846. The UE 602, 702 converts the TA value into an absolute time value in “seconds” using Equation 1 : where p is the subcarrier spacing index as shown on Table 1 , and Tcis the basic timing unit defined in [3]

[0075] Table 1

[0076] In existing networks, the absolute value of the timing advance TTAis applied to an uplink transmission relative to the start time of a DL slot or DL frame for the gNB. In other words, an UL transmission from the UE 702 to the gNB 704 is transmitted by the UE 702 at time TTA prior to the start of a DL slot or DL frame at the gNB 704.

[0077] Timing Advance (TA) adjustment in Connected Mode

[0078] In existing wireless communications networks, after a UE has established a connection with a cell, the timing advance is maintained and modified as the propagation delay changes due to UE mobility within the same cell. In this case, the gNB regularly measures the propagation delays from the UE, for example based on received UL Sounding Reference Signal (SRS), PUSCH and / or PUCCH, and / or the gNB commands the UE to transmit a random-access preamble (PRACH) using a PDCCH whilst in RRC connected state. In response, the gNB sends an update of TA value based on measurement of the received UL signals. In other words, gNB includes TA updates in the downlink PDSCH transmissions (known as Timing Advance MAC Control Element) for the UE. In this way, the UE adjusts its future uplink transmissions based on the new TA value.

[0079] In addition, the network configures a timer known as timeAlignmentTimer (e.g., per Timing Alignment Group (TAG) of cells) which controls how long the MAC entity considers the Serving Cells belonging to the associated TAG to be uplink time aligned. Hence, if this timer expires at the network or UE, the UL is considered not to be time aligned. In this case, either the network or UE initiates random access procedure for UL synchronization.

[0080] In some networks, before the timer expires the network can send a TA adjustment to the UE based on received UL signals. The network sends Timing Advance Command MAC CE as shown in Figure 8, which includes a TAG ID and Timing Advance Command where the Timing Advance Command indicates the index value TA(0, 1 , 2... 63) used to control the amount of timing adjustment that the UE’s MAC entity must apply. The length of the TA command is 6 bits.

[0081] Timing Advance in HetNets In some scenarios in conventional HetNets, it is beneficial for a UE to handover from a TRP providing a macro cell to a TRP providing a small cell or vice versa. For example, for a given UE location, a particular TRP may provide a better signal strength than other TRPs. In order to decide whether to perform a handover, the UE typically receives downlink signals from each of the TRPs in a HetNet and measures a signal strength of each of the downlink signals. The UE then decides to form a wireless communications link with the TRP which transmitted the downlink signal with the highest signal strength. During the formation of the wireless communications link, the UE synchronises with the TRP. The UE receives a downlink synchronization signal block (SSB) from the TRP and uses this to perform downlink synchronisation with the TRP. After downlink synchronisation, the UE receives system information comprising a UL bandwidth part (BWP) and random-access resources for uplink synchronisation. The UE transmits a PRACH preamble using the RACH resources to the TRP. The TRP determines a propagation delay between the TRP and the UE and, because uplink reception and downlink transmission are co-located on the TRP, the TRP also works out the timing advance (also known as the round-trip time) by multiplying the propagation delay by two. The timing advance is then transmitted to the UE to complete uplink synchronisation.

[0082] However, technical challenges arise in efficiently forming wireless communications links with URPs in a HetNet because URPs are unable to transmit downlink transmissions and, therefore, uplink and downlink transmissions are not co-located on a URP. For example, the UE is faced with technical problems, firstly, in determining whether to form a wireless communications link with a URP because the UE cannot receive downlink signals from the URP to measure for received signal strength and, secondly, in synchronising uplink transmissions between the UE and the URP because uplink reception and downlink transmission are not co-located. Furthermore, since a URP does not transmit in the DL, and therefore does not transmit any SSBs, the UE cannot detect its presence. That is, the UE would not be aware whether or not it is within the UL coverage of a URP. For initial access, it is therefore challenging for the UE to direct its PRACH preamble towards an appropriate URP. Additionally, since a URP does not transmit in the DL, the UE is unable to utilise a DL transmission from the URP to determine the timing of a DL slot or frame. As such, the UE may be unaware to what timing the TA for the URP should be applied.

[0083] The network may wish to switch the UL connection of the UE between URP and TRP or between two different URPs, for load balancing purpose or due to changes to radio condition of the UE. Since the URPs are likely to be in different locations to the TRPs, particularly the gNB providing a macro cell (such as gNBs 402 and 502), the UE needs to use different TAs for its uplink transmissions when it switches between a URP and a TRP, and between two different URPs.

[0084] In existing networks, for carrier aggregation (CA), the UE maintains at least two-timing advances (TA), e.g., one with a macro-TRP (e.g., DL1+UL1) and another with a micro-TRP (e.g., DL2+UL2) where for each TRP, the DL and UL are co-located [4], For example, in Figure 9, a UE operating in CA is served by a first TRP 902 and a second TRP 912. The first TRP 902 provides a macro cell 904 for a UE 930 located within the macro cell 904. The TRP 912 providing a small cell 914 for the UE 930, where the UE 930 is located in both the macro cell 904 and the small cell 914, and wherein the small cell 914 is located within the macro cell 904. Although not shown in Figure 9, the second TRP 912 may be connected to the first TRP 902 via wired backhaul connections such as fiber optic cables, thereby allowing communication between the first TRP 902 and the second TRP 912. When the second TRP 912 is connected to the first TRP 902, scheduling may be coordinated and multi-TRP MIMO may be provided. The first TRP 902 may also be referred to as a network infrastructure equipment, transceiver station, nodeB, e-nodeB, eNB, g-nodeB, gNB and so forth. Therefore, for clarity the first TRP 902 will be hereinafter referred to as a gNB 902, and the second TRP 912 will be referred to as a TRP 912, though it should be appreciated that this terminology is not intended to be limiting. As such, the UE 930 may receive DL transmissions 906 from the gNB 902 and transmit UL transmissions 908 to the gNB 902. In addition, the UE 930 may receive DL transmissions 916 from the TRP 912 and transmit UL transmissions 918 to the TRP 912.

[0085] The UE 930 therefore uses two different Timing Advances (TAs) based on whether the UE 930 is transmitting to the gNB 902 or the TRP 912. In particular, the UE 930 has two TAs, a first timing advance TAgNBwith the gNB 902, and a second timing advance TATRP with the TRP 912. Assuming the DL slots are synchronized between the TRP 912 and the gNB 902, then TA TRP ** TAgNB, since the propagation delay between the TRP 912 and the UE 930 TTRP, is smaller than the propagation delay TgNBbetween the UE 930 and the gNB 902. It should be noted that the timing uplink transmissions using TAgNBand TATRP are relative to the DL slot boundaries of the gNB 902 and TRP 912 respectively. In particular, as shown in the bottom of Figure 9, DL Slot n for both the gNB 902 and TRP 912 starts at time t2 but arrive at the UE 930 at times t4 and t3respectively. Hence, the timing advance TAgNBfor UL Slot n for transmitting to the gNB 902 is relative to time t4 and the timing advance TATRP for UL Slot n for transmitting to the TRP 912 is relative to time t3.

[0086] In such an arrangement, each TA maintained by the UE 930 has a paired UL and DL timing. That is, the UL is transmitted a time TA prior to the start of a DL slot boundary time for the TRP / gNB, as received by the UE 930 (i.e. , indicated to the UE by the TRP / gNB), as shown in the bottom of Figure 9. However, URPs are not capable of transmitting DL transmissions. As such, if the UE 930 is connected to a URP, the URP cannot transmit an indication of a DL slot boundary time for the URP. Therefore, the UE 930 may be unaware of how a timing advance for the URP should be applied.

[0087] Figure 10 shows an example according to the present disclosure. In addition to the features and entities show and discussed in relation to Figure 9, the arrangement in Figure 10 additionally includes a URP 922, providing a cell 924 located at least partially within the macro cell 904 provided by the gNB 902. When located within the cell 924, the UE 930 may transmit UL transmissions 928 to the URP 922, but the URP 922 cannot transmit DL transmissions to the UE 930. While not shown, the URP 922 is connected to the gNB 902 (an optionally the TRP 912) via a backhaul communications link.

[0088] According to the present example, in such an arrangement, the UE 930 is provided with a reference timing, which the TA for the URP is applied relative to. That is, as there is no DL slot boundary time for the URP, the UE uses a different time value to use as the reference timing. Accordingly, the network (e.g., the gNB 902) maintains at least two different TAs for the UE 930 for non-co-located UL connections.

[0089] In some examples, the reference timing for the URP is the received DL timing of one of the gNB 902 or TRP 912. That is, the reference timing is the timing of a DL slot / frame for the gNB 902 or TRP 912, as received by the UE 930. For example, in Figure 10, the gNB 902, TRP 912 and URP 922 are within coverage of a macro cell 904. The UE 930 may be scheduled to transmit UL transmissions to the gNB 902, the TRP 912 and / or the URP 922, and therefore needs to maintain 3 TAs, namely TAgNB, TATRP and TAURP with the gNB 902, the TRP 912 and the URP 922 respectively. TAgNBand TATRP have their respective DL reference time which is relative to their DL slot boundaries, as respectively received at the UE 930. That is, as shown in the bottom of Figure 10, the gNB 902 and TRP 912 DL slots n begin at time t3, where the gNB 902 and 912 DL slots are synchronized in time (though in some examples the gNB 902 and 912 DL slots may not be synchronized in time). Due to the propagation delay between the gNB 902 and the UE 930, based on one or more DL transmissions 906 from the gNB 902 to the UE 930, the gNB 902 DL slot n begins at the UE 930 at time ts. Similarly, due to the propagation delay between the TRP 912 and the UE 930, based on one or more DL transmissions 916 from the TRP 912 to the UE 930, the TRP 912 DL slot n begins at the UE 930 at time t4. For the UL transmission 908 to the gNB 902, the UE 930 applies the timing advance TAgNBrelative to the gNB 902 DL slot timing, meaning the UL transmission 908 to the gNB 902 is transmitted at time TAgNBprior to ts, such that the UL transmission to the gNB 902 is transmitted at time to. Similarly, for the UL transmission 918 to the TRP 912, the UE 930 applies the timing advance TATRP relative to the TRP 912 DL slot timing, meaning the UL transmission 918 to the TRP 912 is transmitted time TATRP prior to t4, such that the UL transmission to the TRP 912 is transmitted at time t2.

[0090] As discussed above, the URP 922 cannot provide the UE 930 with a DL reference timing, and as such according to the present disclosure the UE 930 may be provided with a reference timing TRef to use for the timing advance TAURP for an UL transmission 928 to the URP 922. For example, the reference timing TRef may be the DL reference timing for the gNB 902 or TRP 912 (i.e., times ts or t4 respectively). An example is shown in Figure 10, where the reference timing is the DL reference timing for the TRP 912 (i.e., the timing of a DL slot / frame for the TRP 912, as received by the UE 930), shown as time t4. Accordingly, the UE 930 may apply the timing advance TA URP for an UL transmission 928 the URP 922 relative to time t4, such that the UE 930 transmits the UL transmission 928 to the URP 922 TAURP prior to time t4, meaning the UL transmission 928 the URP 922 is transmitted by the UE 930 at time ti. In other examples, the reference timing TRef may be the DL reference timing for the gNB 902 (i.e., the timing of a DL slot / frame for the gNB 902, as received by the UE 930), shown as time ts. Accordingly, the UE 930 may apply the timing advance TAURP for an UL transmission 928 the URP 922 relative to time ts, such that the UE 930 transmits the UL transmission 928 the URP 922 TAURP prior to time ts.

[0091] As such, the absolute value (in milliseconds) of TAURP is dependent on the reference timing TRef used, as well as the propagation delay between the UE 930 and the URP 922. For example, if the UE 930 is to transmit the UL transmission 928 to the URP 922 at time ti in order to account for propagation delay, the value of TAURP is different based on whether TAURP is applied relative to t4 or ts. The UE 930 may determine what time to use for TRef in a number of ways. For example, the UE 930 may be configured by the network (i.e., by signaling from the gNB 902 and / or TRP 912) to use a particular TRef via RRC signaling. Additionally or alternatively, the UE 930 may be configured by the network (i.e., by signaling from the gNB 902 and / or TRP 912) to use a particular TRef dynamically in a downlink control information (DCI) transmission from the gNB 902 and / or TRP 912, such as a group common DCI (GC- DCI), DL Grant, and / or UL Grant. Furthermore, in some cases reference time TRefmay be predefined (i.e., defined in technical specifications, such as 3GPP specifications). That is, the UE 930 may be preconfigured to use a DL slot timing for a gNB 902 providing a macro cell 904 in which the URP 922 is located (or some other timing) as TRef.

[0092] As shown in Figure 5, a HetNet may include multiple URPs within a macro cell. In such cases, a UE may have different timing advances TAURP for the different URPs due to different propagation delays. In such cases, a single reference time TRef may be used for all the URPs in a macro cell. For example, the DL timing of the gNB providing the macro cell can be used as the reference time for all URPs within the coverage of the gNB, DL transmissions from the gNB may reach all UEs in the cell. In other examples, different reference times may be used for different URPs within a macro cell. Moreover, these examples may be combined such that the same reference time may be used for some of the URPs within the macro cell, while a different reference time may be used for other URP(s) within the macro cell.

[0093] Furthermore, while the reference timing TRefhas been described primarily as a DL reference timing, it should be appreciated that the reference timing TRefmay in fact take many forms and is not limited to a DL reference timing. For example, the reference timing TRef may be a global timing (i.e. a global satellite-based timing e.g. derived from Global Navigation Satellite System (GNSS)). That is, if a UE has GNSS capability, the UE may determine a boundary of a slot / subframe by calculation of mod(global time, slot / subframe length)=0, and may use the result of this calculation as TRef.

[0094] It should be appreciated that the reference timing TRef is also applicable for transmission of PRACH or msgA in a random access procedure targeting a URP. That is, a UE transmits a PRACH (i.e. random access preamble) at the start of the received DL slot boundary. Therefore, although the PRACH is not timing advanced, in an arrangement with multiple TRPs, and therefore multiple DL slot boundary timings, a UE may needs to determine in which DL slot boundary timing the PRACH should be transmitted for a particular URP. Therefore, in some implementations, the reference timing TRef, is used for a random access procedure, where the UE transmits its PRACH or msgA at the reference timing TRef.

[0095] 5G / NR Discovery and Synchronisation Procedures

[0096] Figure 8 illustrates a method operating a communications device in accordance with example embodiments. The method starts in step S1.

[0097] In step S2, the method comprises receiving, from a transmission and reception point, TRP, of a heterogeneous communications network, an assistance signal comprising information for the communications device to determine whether to form a wireless communications link with an uplink-only reception point, URP, of the heterogeneous communications network for transmitting uplink transmissions to the URP. The URP is configured to transmit signals to, and receive signals from, the TRP via a backhaul communications link. The TRP provides a cell for the communications device to transmit uplink transmissions to, and receive downlink transmissions from, the TRP when the communications device is located within the cell provided by the TRP. The URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the URP when the communications device is located within the uplink-only cell. The URP is unable to transmit downlink transmissions to the communications device. In some embodiments, the uplink-only cell is located within the cell provided by the TRP. In some embodiments, the uplink only cell is smaller than the cell provided by the TRP. In some embodiments, the uplink-only cell is smaller than, and located within, the cell provided by the TRP.

[0098] The communications device may be a UE, for example.

[0099] The TRP may be a macro-TRP (or macro gNB) providing a macro-cell, for example. Although, it will be appreciated that the TRP is not required to be a macro-TRP but may be any TRP which is connected to the URP via a backhaul communications link.

[0100] In some embodiments, the TRP and URP may be synchronised in time. For example, the TRP and URP may be synchronised at a slot, subframe, or radio frame level. In some embodiments, the TRP and the URP are not synchronised in time, but are offset in time by a known offset. In some embodiments, the TRP and the URP use a same carrier frequency. In other embodiments, the TRP and the URP use different carrier frequencies. The UE may be preconfigured to know the carrier frequency used by the URP.

[0101] In some embodiments, the assistance signal comprises an indication of a downlink received reference power threshold, RSRP, and the determining to form the wireless communications link with the URP comprises determining that an RSRP of a downlink signal received by the communications device from the TRP is below the downlink RSRP threshold. The low RSRP is an indication that the communications device is near an edge of the cell provided by the TRP, and therefore is likely close to the URP (particularly, in a dense cell deployment). In some embodiments, the assistance signal comprises, in addition to the RSRP threshold, one or more of an uplink bandwidth part or random-access resources for transmission of the synchronisation signal to the URP.

[0102] In some embodiments, the assistance signal comprises an instruction for the communications device to form the wireless communications link with the URP, and the determining to form the wireless communications link with the URP comprises identifying that the assistance signal comprises an instruction for the communications device to form the wireless communications link with the URP.

[0103] In some embodiments, the assistance signal is transmitted in system information block (SIB).

[0104] In step S3, the method comprises determining, based on the assistance signal, to form the wireless communications link with the URP.

[0105] In step S4, the method comprises forming the wireless communications link with the URP. The forming of the wireless communications link with the URP comprises transmitting a synchronisation signal to the URP.

[0106] The synchronisation signal may be a PRACH preamble or a Sounding Reference Signal, for example.

[0107] In some embodiments, the forming of the wireless communications link may comprise handing over from communicating uplink transmissions with the TRP to communicating uplink transmissions with the URP. In some embodiments, the forming of the wireless communications link comprises performing initial access with the URP when the communications device is in an RRC idle or RRC inactive state with respect to the TRP.

[0108] The method ends in step S5.

[0109] By determining whether to form a wireless communications link with a URP based on an assistance signal received from a TRP, a communications device can efficiently establish a connection with a URP, and thereby alleviate a load on the TRP caused by uplink traffic, and efficiently establish a connection with a URP.

[0110] In the following description, the communications device will be referred to as a “UE”, but it will be appreciated that the UE may be any communications device. Furthermore, it will be appreciated that, in the following description, the TRP being referred to may be a macro TRP.

[0111] UE-initiated Synchronisation

[0112] Since URPs cannot transmit downlink signals to a UE, it is difficult for a UE to know whether it will be beneficial to attempt to form a wireless communications link with a URP. For example, it is difficult for a UE to know whether there are any URPs which are nearby the UE. In some embodiments, the assistance signal comprises an indication of a received reference power threshold, RSRP, threshold. The UE may measure an RSRP of a downlink signal received from the TRP. If the measured RSRP of the downlink signal is below the received RSRP threshold, the UE may determine to form a wireless communications link with a URP. This recognises that, if the RSRP of the downlink signal is low, then the UE is likely near a cell edge of a cell provided by the TRP. Consequently, the UE is likely to be close to a URP which are often deployed near the edge of the cell provided by the TRP. Therefore, the URP is likely to be able to successfully receive uplink transmissions from the UE. Furthermore, if the UE is close to the URP, then the UE will be able to transmit uplink transmissions at a lower power (or higher modulation and coding scheme (MCS)) than the transmission power (or MCS) which was used for uplink transmissions to the TRP. The assistance signal comprising the RSRP threshold may be transmitted in system information (such as an SIB) in some embodiments.

[0113] In some cases, even though the RSRP of the downlink signal is below the RSRP threshold, there may not be a URP near-by the UE. Therefore, a scenario may arise where the UE determines that the RSRP of the downlink signal is below the RSRP threshold and transmits the synchronisation signal to the URP, even though the URP may not be near-by. In this case, since the URP is far away from the UE, the UE may not receive a response to the synchronisation signal from the TRP. For example, although the TRP may transmit a response to the synchronisation signal to the UE, the RSRP of the response at the location of the UE may be too low for the UE to detect. Therefore, in some embodiments, if the UE does not receive a response to the synchronisation signal from the TRP for a pre-defined time interval, then the UE will re-transmit the synchronisation signal to the URP. The pre-defined time interval may be transmitted by the TRP to the UE and may be included in the assistance signal. The retransmission of the synchronization signal to the URP may be transmitted at a higher power.

[0114] In some embodiments, the pre-defined time interval is a periodic time interval. In other words, the UE may periodically retransmit the synchronisation signal to the URP if the UE does not receive a response to the synchronisation signal from the TRP.

[0115] Embodiments in which the UE implements the time interval, UE power consumption can be reduced compared to cases where the UE continuously monitors whether an RSRP of received downlink signals from the TRP fall below the RSRP threshold.

[0116] Network Initiated Synchronisation

[0117] In some embodiments, the TRP may determine that the UE should form a wireless communications link with a URP and, in response, includes an instruction in the assistance signal instructing the UE to form the wireless communications link with the URP. In some embodiments, the instruction in the assistance signal comprises a Physical Downlink Control Channel, PDCCH, order comprising an identification of the synchronisation signal to transmit to the URP.

[0118] In some embodiments, the UE receives a downlink signal from the TRP, measures an RSRP of the received downlink signal, and transmits an indication of the RSRP to the TRP. Then, based on the RSRP, the TRP determines that the UE should form a wireless communications link with a URP. For example, if the TRP determines that the RSRP is below a threshold, then the TRP transmits the assistance signal comprising the instruction to form a wireless communications link with the URP.

[0119] In some embodiments, the UE transmits, to the TRP, an indication of a location of the UE in the cell provided by the TRP. The TRP may determine that the UE should form a wireless communications link with a URP based on the indication of the location received from the UE. In some embodiments, the UE may transmit, to the TRP, information regarding a nearest TRP to the UE. The TRP may determine that the UE should form a wireless communications link with a URP based on the information regarding the nearest TRP to the UE. For example, the UE may transmit one or more of an indication of a location of the nearest TRP, a downlink beam direction of the nearest TRP or an uplink beam direction of the nearest TRP.

[0120] In some embodiments, where the TRP and the URP operate in the same frequency of the uplink spectrum, the URP may receive uplink transmissions intended for the TRP (e.g., SRS). In such embodiments, the URP may forward an indication to the TRP that the URP received uplink transmissions from the UE. Based on this, the TRP may determine that the UE is close to the URP and therefore determines that the UE should form a wireless communications link with the URP.

[0121] Determining Timing Advance for a URP

[0122] Figure 12 illustrates a method of operating a communications device in accordance with example examples. The method starts in step S10.

[0123] In step S20, the method comprises determining to form a wireless communications link with an uplink-only reception point, URP, of a heterogeneous communications network for transmitting uplink transmissions to the URP.

[0124] For example, the communications device may determine to form a wireless communications link with the URP based on an assistance signal received from the TRP using any one of the methods previously discussed herein.

[0125] In other examples, the communications device may periodically, or at predefined time intervals, determine to form, or attempt to form, a wireless communications link with a URP.

[0126] In steps S30, S40 and S50, the method comprises forming the wireless communications link with the URP.

[0127] In step S30, the forming the wireless communications link with the URP comprises transmitting a synchronisation signal to the URP.

[0128] In step S40, the forming of the wireless communications link with the URP comprises receiving, from a transmission and reception point, TRP, of the heterogeneous communications network a response to the synchronisation signal comprising an indication of a propagation delay between the URP and the communications device.

[0129] An “indication of a propagation delay” may be a one-way propagation delay or a two-way propagation delay (known as Timing Advance (TA)), for example.

[0130] In step S50, the forming the wireless communications link with the URP comprises using the indication of the propagation delay to synchronise a transmission time of each of the one or more uplink transmissions at the communications device with a reception time of each of the one or more uplink transmissions at the URP. The TRP provides a cell for the communications device to transmit uplink transmissions to, and receive downlink transmissions from, the TRP when the communications device is located within the cell provided by the TRP. The URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the URP when the communications device is located within the uplink-only cell. The URP is unable to transmit downlink transmissions. The uplink-only cell is smaller than, and located within, the cell provided by the TRP.

[0131] The method ends in step S60. Therefore, in accordance with some examples, the communications device can receive the indication of the propagation delay between the communications device and the URP from the TRP and use this to synchronise uplink transmissions with the TRP. Consequently, examples can provide a way to efficiently synchronise uplink transmissions with URPs even though uplink and downlink transmissions are not co-located.

[0132] An example of determining a propagation delay between a UE and a URP will now be described with reference to Figures 13 and 14. In Figure 13, a UE 1004 is initially in an RRC connected mode with a TRP 1002 (such as a macro-TRP) and can therefore transmit uplink transmissions 1008 to the TRP 1002 and receive downlink transmissions 1006 from the TRP. Although not shown, the UE 1004 is located within a cell provided by the TRP 1002. As shown in Figure 13, a URP 1012 is located nearby the UE 1004. The URP 1012 is connected to the TRP 1002 via a backhaul communications link (which may be a wired communications link, for example, such as a fiber optic cable). In the example shown in Figure 13, the URP 1012 and TRP 1002 are synchronised in time. The UE 1004 may determine to form a wireless communications link with the URP, for example, by using any of the methods of determining to form the wireless communications link with the URP 1012 discussed in this disclosure. As part of forming the wireless communications link with the URP 1012, the UE 1004 transmits a synchronization signal 1010 to the URP 1012.

[0133] Figure 14 schematically illustrates propagation delays between the UE 1004, URP 1012 and TRP 1002 shown in Figure 13. As will be appreciated from Figure 14, if the TRP 1002 transmits a downlink transmission in slot 1102, then the UE 1004 receives this downlink transmission in a slot 1104 which is delayed by tpifrom the slot 1102 in which the downlink transmission is transmitted. Therefore, the one-way propagation delay between the TRP 1002 and the UE 1004 is tpi. As shown in Figure 14, a slot 1106 at the URP 1012 when the TRP 1002 transmits the downlink transmission 1006 to the UE 1004 is aligned with the slot 1102 at the TRP 1002. Therefore, the TRP 1002 and the URP 1012 are synchronised in time. As will be appreciated from Figure 14, if the UE 1004 transmits an uplink transmission (such as a PRACH preamble) to the URP 1012 in a slot 1108, then the uplink transmission will be received at the URP 1012 in a slot 1110 which is delayed by tP2 from the slot 1108 at the UE 1004 in which the uplink transmission was transmitted. Therefore, a one-way propagation delay between the UE 1004 and the URP 1012 is tp2. Furthermore, a one-way propagation delay between the TRP 1002 and the URP 1012 via the UE 1004 is tpi+ tp2.

[0134] In accordance with some examples, the TRP 1002 may determine the one-way propagation delay tp2between the UE 1004 and the URP 1012. For example, the TRP 1002 may determine tP2 based on Equation 2 below. tp2= (tPi+tp2) - (2*tpi) / 2 (2)

[0135] The one-way propagation delay tpibetween the TRP 1002 and the UE 1004 is known to the TRP 1002 by employing legacy RACH procedure. In this procedure, the TRP 1002 measures the two-way propagation delay (2*tpi) between the TRP 1002 and the UE 1004, and thus determines the one-way propagation delay tpibetween the TRP 1002 and the UE 1004 by dividing the measured value by 2. Furthermore, while the network (i.e. the TRP 1002 and / or URP 1012) cannot directly measure the one-way propagation delay tp2between the UE 1004 and the URP 1012, the one-way propagation delay, tpi+tp2, between the TRP 1002 and the URP 1012 via the UE 1004 is known to the URP 1012. For example, the URP 1012 may determine tpi+tp2based on a time at which the synchronisation signal 1010 is received from the UE. In accordance with some examples, the URP 1012 may transmit an indication of tpi+tp2to the TRP 1002. Then, the TRP 1002 may determine tp2using Equation 2. Then, the TRP 1002 may transmit, to the UE 1004, a response (such as a RAR) to the synchronisation signal 1010 comprising an indication of tp2to the UE 1004. For example, indication of tp2may be a TA based on the propagation delay between the UE 1004 and the URP 1012 (i.e., TA = 2*tp2).

[0136] Modification of Timing Advance for a URP

[0137] As discussed above with reference to Figures 13 and 14, if a UE 1004 is connected to both a TRP / gNB 1002 (hereinafter referred to as a gNB) and a URP 1012, at least two TAs must be maintained for the UE: one for UL transmissions 1008 to the gNB 1002 and another for UL transmissions 1010 to the URP 1012. While the TA for a gNB 1002 TAgNBcan be maintained and modified independently (e.g., based on a measured propagation delay between the gNB and the UE), setting and maintaining the TA value TAURP for UL transmissions 1010 to the URP 1006 requires knowledge of TASNB-

[0138] In particular, when transmitting UL transmissions 1010 to a URP 1012, the one-way propagation delay for a UE 1004 is not symmetrical. That is, the UE 1004 transmits the UL 1010 and DL 1006 transmissions to different entities (i.e., UL 1010 is transmitted to the URP 1012, while the DL 1006 are received from the gNB), such that the DL 1006 and UL 1010 directions are not co-located. As discussed above, the network cannot directly measure the UL 1010 propagation delay tp2from the UE 1004 to the URP 1012. Instead, the network can only measure the combined value tpi+tp2, which is the combined propagation delay from the gNB 1002 to the URP 1012 via the UE 1004. Therefore, if the UL 1010 propagation delay tp2changes (e.g., due to movement of the UE 1004), the network may not be able to determine the new value of tp2without knowing the current value of tpi, and as such may not be able to update the timing advance for transmitting UL transmissions 1010 to the URP 1012.

[0139] Therefore, according to the present disclosure, in order for the network to determine the current value of tpi, the network measures the two-way propagation delay (2*tpi) between the gNB 1002 and the UE 1004, and the two-way propagation delay (tpi+tp2) from the TRP 1002 to the URP 1012 via the UE 1004 at the same time, or within a threshold time of one another. Accordingly, the updated propagation delay tp2-new is given by Equation 3 below: tp2_new=(tp1 +tp2)- (2*tpl) / 2 (3) where 2*tpiis the timing advance TAgNB for transmitting from the UE 1004 to the gNB 1002. Therefore, Equation 3 can be re-written as follows in Equation 4 below: tp2_new=(tp1 +tp2)- (TAgNB) / 2 (4)

[0140] As such, the UE may determine an updated one-way propagation delay tp2-new from the UE 1004 to the URP 1012 based on TA9NB, where the updated timing advance TAuRp_new for transmitting from the UE 1004 to the URP 1012 is set to (2*tp2-new). The network may periodically or dynamically update TA9NB, and as such the network may determine that when determining TA9NB, the network should also determine (tpi+tp2) in order to calculate TAuRp_new, based on the same measurement of (2*tpi) as that used to calculate TA9NB.

[0141] Based on the determined value of tp2-new, a correction value A for the current timing advance TAuRp_oid for transmitting from the UE 1004 to the URP 1012 can be derived by Equation 5 below:

[0142] A — 2 (tp2_old tp2_new) (5) where tp2 oid is the one-way propagation delay measured during initial access procedure or in the previous measurement update.

[0143] The correction value A is then converted to a relative timing advance value TA, in a range of 0,1 , 2, 3... , 63. The UE 1004 receives the TA(e.g. in a Timing Advance Command MAC CE), and then converts the relative TAinto an absolute time value (e.g. in seconds or milliseconds) as follows in Equation 6:

[0144] TTA.new where Tcand p are defined above with respect to Equation 1 . The network (i.e., the gNB 1002 or another TRP) may then inform the UE 1004 of the new timing advance TTA newfor the URP 1012, and the UE 1004 then applies the new timing advance TTA newwhen transmitting subsequent UL transmissions to the URP 1012.

[0145] Time Alignment Timer for a URP

[0146] As discussed above in relation to Figure 8, for each URP / TRP to which the UE is connected, the network may configure an alignment timer timeAlignmentTimer, where each alignment timer is associated with one UL TRP. The timeAlignmentTimer may be maintained by the network (i.e. gNB / TRP / URP) and / or the UE). The timeAlignmentTimer indicates a remaining length of time for which the UE is considered to be synchronized with the TRP for UL transmissions. In particular, the propagation delay between a UE and a TRP may change over time (e.g. due to movement of the UE). As such, a UE can only be considered to be synchronized with the TRP for a set amount of time, after which the UE may need to be resynchronized with the TRP by modifying the timing advance for the TRP.

[0147] In the same manner, the network may configure a timeAlignmentTimertor the URP(s) to which the UE is connected. In some cases, each timer may be associated with a single URP / TRP. In this case, the URPs / TRPs may belong to different Timing Advance Groups (TAGs) of the same cell or different cells (if there is different cell IDs). For example, a gNB providing a macrocell may belong to a primary TAG (PTAG), while a URP may belong to a secondary TAG (STAG). Furthermore, multiple URPs within the same macro cell may belong to the same TAG, or to different TAGs.

[0148] If one or more alignment timers for a particular UL TRP (i.e. a URP or TRP) expire, and e.g. network has data from the UE that has recently arrived, the network can send a DL (e.g. PDCCH) order to the UE to initiate a random access procedure for an UL TRP e.g. by transmitting a random access preamble (PRACH), whereupon receiving the PRACH the network determines the timing advance the UE should apply when transmitting to the UL TRP receiving the PRACH. In this case, the UE may need to identify which UL TRP the PDCCH order is intended for (i.e. to which UL TRP the UE should transmit the PRACH). As such, the PDCCH order may contain means to identify the UL TRP. For example, the PDCCH may include a URP / TRP index (i.e., where UL TRPs are sequentially indexed) or a cell index; a scheduling DCI which includes one or more bits indicating whether the DCI is for a URP, TRP, or gNB; a set of physical resources (e.g. Control Resource Sets (CORESETs)) or a search space for a DCI scheduling for the gNB and / or URP; a temporary identifier (e.g. a Radio Network Temporary Identifier (RNTI) for the gNB and / or URP; and / or a TAG ID / identifier in which the gNB and / or URP is included. In addition or alternatively to an identification of the UL TRP in the manner described above, the PDCCH order may include a preamble index / ID for contention free random access (CFRA), and / or a SRS identifier, based on which the UE may identify the UL TRP.

[0149] In some examples, if a timeAlignmentTimer for the URP / TRP has expired and a UE determines that it has an UL transmission to transmit, the UE may initiate a random access procedure by transmitting a PRACH to the URP / TRP. This PRACH may be received by a single URP / TRP, where the network may determine the new TA value for the UE for the URP / TRP. Alternatively, the PRACH may be received by multiple URPs / TRPs, where the network may determine new TA values for the UE for the URPs / TRPs that received the PRACH. Moreover, in some cases, if an alignment timer for a single URPs / TRP has expired i.e. , if only one UE-URP / TRP (UL) link is not time synchronized), the network may calculate an updated timing advance for only the unsynchronized link, or for the unsynchronized link and one or more other synchronized links.

[0150] Additionally or alternatively, if an alignment timer for a first UE-URP / TRP UL link has expired, but a second synchronized UE-URP / TRP links exits, the UE may inform the network via the second synchronized / time-aligned link that the first link is not time-aligned. Accordingly, the network may initiate transmit a PDCCH order to the UE for the UE to initiate a random access procedure for the first link.

[0151] In examples according to the present disclosure, the network may permit a UE to have two simultaneous UL connections, one for to a gNB / TRP and another to a URP. In such cases, a UE may determine whether to transmit its UL transmission to the gNB / TRP or to the URP. However, in other examples, the network (i.e. gNB / TRP) may indicate in a scheduling DCI, which of the gNB / TRP and URP the UE should transmit the UL transmission to for a particular UL transmission time. Accordingly, the UE may dynamically switch between transmitting to the gNB / TRP and the URP. Furthermore, in some examples, the network may schedule (e.g. in a scheduling DCI) UL resources for the UE to transmit simultaneously to both the gNB / TRP and the URP.

[0152] Figure 15 illustrates an example method for a communications device (e.g. a UE) according to the present disclosure. Step S10 includes identifying a reference timing for a URP. The reference timing may, for example, be indicated to the communications device or predefined. Step S20 of the method includes determining, based on the identified reference timing, a time at which to transmit an UL transmission to the URP. For example, the communications device may determine to transmit a PRACH transmission to the URP at the reference timing, or may determine a timing advance for transmitting an uplink transmission to the URP. Step S30 of the method includes transmitting the UL transmission to the URP at the determined time.

[0153] Figure 16 illustrates an example method for an uplink-only reception point (i.e. an uplink-only infrastructure equipment) according to an example of the present disclosure. Step S110 includes receiving, directly from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time. Step S120 includes receiving, via the first URP, a second uplink transmission from the communications device, wherein the second uplink transmission is transmitted by the communications device at a second time, wherein the communications device determines the second time based on a first reference timing, and wherein the second time is different to the first time. Steps S110 and S120 may be performed in any order, such that Step S110 is performed before Step S120, or Step 120 may be performed Step S110, or Steps S110 and S120 may be performed concurrently.

[0154] Figure 17 illustrates an example method for a transmission and reception point (i.e. an infrastructure equipment) according to an example of the present disclosure. Step S210 includes receiving, from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time, wherein the communications device determines the first time based on a first reference timing. The method may further include an optional step S220 of transmitting, to the TRP via the backhaul communications link, the first uplink transmission received from the communications device.

[0155] Further examples according to the present disclosure are set out in the following numbered clauses: 1. A method of operating a communications device configured to transmit signals to and / or to receive signals from a first transmission and reception point, TRP, of a wireless communications network via a wireless radio interface provided by the wireless communications network, the method comprising: identifying a first reference timing for a first uplink-only reception point, URP, of the wireless communications network, the first URP being configured to transmit signals to, and receive signals from, the first TRP via a backhaul communications link, wherein the first TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the first TRP when the communications device is located within the cell provided by the first TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink- only cell, the first URP being unable to transmit downlink transmissions to the communications device; wherein the method further comprises: determining, based on the identified first reference timing, a first time at which to transmit a first uplink transmission to the first URP; and transmitting the first uplink transmission to the first URP at the first time.

[0156] 2. The method according to clause 1 , wherein determining the first time comprises identifying a first timing advance for the first URP relative to the first reference timing; and wherein the first uplink transmission to the first URP at the first time comprises transmitting the first uplink transmission to the first URP according to the determined first timing advance.

[0157] 3. The method according to clause 1 or clause 2, further comprising: receiving, from the first TRP, an indication of the first reference timing.

[0158] 4. The method according to clause 3, wherein the communications device receives the indication of the first reference timing via RRC signalling.

[0159] 5. The method according to clause 3 or clause 4, wherein the communications device receives the indication of the first reference timing via one or more system information blocks (SIBs).

[0160] 6. The method according to any of clauses 3-5, wherein the communications device receives the indication of the first reference timing via downlink control information.

[0161] 7. The method according to any of clauses 2-6, further comprising: transmitting, to the TRP, a second uplink transmission according to a second timing advance, wherein the second timing advance is different to the first timing advance.

[0162] 8. The method according to any of clauses 2-7, wherein identifying the first timing advance relative to the first reference timing comprises: receiving a first downlink transmission including an indication of a modification to the value of the first timing advance.

[0163] 9. The method according to clause 8, wherein the first downlink transmission including the indication of the modification to the value of the first timing advance includes the first reference timing.

[0164] 10. The method according to any of clauses 2-9, further comprising: determining that an alignment timer for the communications device with respect to the first URP has expired; andbased on determining that an alignment timer for the communications device with respect to the first URP has expired, transmitting, to the first URP, a random access preamble.

[0165] 11. The method according to clause 10, wherein determining that an alignment timer for the communications device with respect to the first URP has expired comprises receiving a second downlink transmission instructing the communications device to transmit the random access preamble to the first URP. 12. The method according to clause 11 , wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes a preamble index.

[0166] 13. The method according to clause 11 or clause 12, wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes a reference signal identifier.

[0167] 14. The method according to any of clauses 11-13, wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes an identifier for the first URP.

[0168] 15. The method according to clause 14, wherein the identifier for the first URP is one or more of: an identifier of a time alignment group (TAG) in which the first URP is included; an index for the first URP; an identifier for a control resource set provided by the first URP; an identifier for a search space provided by the first URP; a radio network temporary identifier (RNTI); and / or a single bit within downlink control information.

[0169] 16. The method according to any of clauses 10-15, further comprising: based on determining that an alignment timer for the communications device with respect to the first URP has expired, transmitting, to a second URP of the wireless communications network, the random access preamble.

[0170] 17. The method according to any of clauses 10-16, further comprising: determining that an alignment timer for the communications device with respect to a second URP of the wireless communications network has expired; and based on determining that an alignment timer for the communications device with respect to the second URP has expired, transmitting, to the second URP, a random access preamble.

[0171] 18. The method according to any preceding clause, wherein the first uplink transmission includes a random access preamble, and wherein the first time is the first reference timing.

[0172] 19. The method according to any preceding clause, wherein the uplink-only cell provided by the first URP is smaller than, and located within, the cell provided by the first TRP.

[0173] 20. The method according to any preceding clause, further comprising: identifying a third timing advance for a second URP of the wireless communications network, the second URP being configured to transmit signals to, and receive signals from, the first TRP via a backhaul communications link, wherein the second URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the second URP when the communications device is located within the uplink-only cell, the second URP being unable to transmit downlink transmissions; and transmitting a third uplink transmission to the second URP according to the determined third timing advance.

[0174] 21 . The method according to clause 20, further comprising: identifying a second reference timing for the third timing advance for the second URP; and wherein the communications device identifies the third timing advance relative to the second reference timing.

[0175] 22. The method according to clause 21 , wherein the second reference timing is different to the first reference timing.

[0176] 23. The method according to clause 21 or 22, wherein the second reference timing is the same as the first reference timing. 24. The method according to any of clauses 20-23, further comprising: receiving, from the TRP and in a downlink transmission scheduling an uplink transmission, an indication to transmit the uplink transmission to a particular one of the first and second URPs.

[0177] 25. The method according to any of clauses 20-24, further comprising: receiving, from the TRP and in a downlink transmission scheduling an uplink transmission, an indication to transmit the uplink transmission to both the first and second URPs.

[0178] 26. The method according to any preceding clause, wherein the first reference timing is predefined.

[0179] 27. The method according to any preceding clause, wherein the communications device is further configured to transmit signals to and / or to receive signals from a second TRP of the wireless communications network, the second TRP being configured to transmit signals to, and receive signals from the first TRP via a backhaul communications link, and wherein the second TRP provides a secondary cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the second TRP when the communications device is located within the secondary cell provided by the second TRP, the secondary cell being smaller than, and located within, the cell provided by the first TRP.

[0180] 28. The method according to clause 27, wherein identifying the first reference timing comprises receiving, via the second TRP, the first reference timing.

[0181] 29. The method according to clause 27 or 28, wherein the first reference timing is a received downlink slot timing for the second TRP.

[0182] 30. The method according to any preceding clause, wherein the first reference timing is a received downlink slot timing for the first TRP.

[0183] 31 . The method according to any preceding clause, wherein the first reference timing is a global satellite-based timing.

[0184] 32. A communications device comprising: a transceiver configured to transmit signals to and / or to receive signals from a first transmission and reception point (TRP) of a wireless communications network via a wireless radio interface provided by the wireless communications network, and wherein the transceiver is further configured to transmit signals to a first uplink-only reception point (URP) of the wireless communications network, the first URP being configured to transmit signals to, and receive signals from, the first TRP via a backhaul communications link, wherein the first TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the first TRP when the communications device is located within the cell provided by the first TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device, and a controller configured together with the transceiver to: identify a first reference timing for the first URP; determine, based on the identified first reference timing, a first time at which to transmit a first uplink transmission to the first URP; and transmit the first uplink transmission to the first URP at the first time.

[0185] 33. Circuitry for a communications device, the circuitry comprising: transceiver circuitry configured to transmit signals to and / or to receive signals from a first transmission and reception point (TRP) of a wireless communications network via a wireless radio interface provided by the wireless communications network, and wherein the transceiver circuitry is further configured to transmit signals to a first uplink-only reception point (URP) of the wireless communications network, the first URP being configured to transmit signals to, and receive signals from, the first TRP via a backhaul communications link, wherein the first TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the first TRP when the communications device is located within the cell provided by the first TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device, and controller circuitry configured together with the transceiver circuitry to: identify a first reference timing for the first URP; determine, based on the identified first reference timing, a first time at which to transmit a first uplink transmission to the first URP; and transmit the first uplink transmission to the first URP at the first time.

[0186] 34. A method of operating a transmission and reception point, TRP, of a wireless communications network configured to transmit signals to and / or to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, wherein the TRP is further configured to transmit signals to and / or to receive signals from a first uplink-only reception point, URP, of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; wherein the method comprises: receiving, directly from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time; and receiving, via the first URP, a second uplink transmission from the communications device, wherein the second uplink transmission is transmitted by the communications device at a second time, wherein the communications device determines the second time based on a first reference timing, and wherein the second time is different to the first time.

[0187] 35. The method according to clause 34, wherein the first uplink transmission is received according to a first timing advance, and wherein the second uplink transmission is received according to a second timing advance, wherein the second timing advance is different to the first timing advance.

[0188] 36. The method according to clause 35, wherein the second timing advance is applied relative to the first reference timing.

[0189] 37. The method according to clause 35 or 36, further comprising: transmitting, to the communications device, an indication of a value of the second timing advance relative to the first reference timing.

[0190] 38. The method according to any of clauses 35-37, wherein the TRP is further configured to transmit signals to and / or to receive signals from a second URP of the wireless communications network via a backhaul communications link, wherein the second URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the second URP when the communications device is located within the uplink-only cell, the second URP being unable to transmit downlink transmissions, and wherein the method further comprises: receiving, via the second URP, a third uplink transmission from the communications device, wherein the third uplink transmission is received according to a third timing advance, wherein the third timing advance is different to the first timing advance. 39. The method according to clause 38, further comprising: transmitting, to the communications device, an indication of a second reference timing for the third timing advance for the second URP.

[0191] 40. The method according to clause 39, wherein the second reference timing is the same as the first reference timing.

[0192] 41. The method according to clause 39 or 40, wherein the second reference timing is different to the first reference timing.

[0193] 42. The method according to any of clauses 38-41 , further comprising: transmitting, to the communications device and in a downlink transmission scheduling an uplink transmission, an indication of a particular one of the first and second URPs to which the communications device should transmit the uplink transmission.

[0194] 43. The method according to any of clauses 38-42, further comprising: transmitting, to the communications device and in a downlink transmission scheduling an uplink transmission, an indication for the communications device to transmit the uplink transmission to both the first and second URPs.

[0195] 44. The method according to any of clauses 35-43, further comprising: transmitting, to the communications device, a first downlink transmission including an indication of a modification to a value of the first timing advance.

[0196] 45. The method according to clause 44, wherein the first downlink transmission including the indication of the modification to the value of the first timing advance includes one or more of the first and / or second reference timing.

[0197] 46. The method according to clause 44 or 45, further comprising: determining that an alignment timer for the communications device with respect to the first URP has expired; and based on determining that an alignment timer for the communications device with respect to the first URP has expired, transmitting, to the communications device, a second downlink transmission including an instruction to transmit a first random access preamble to the first URP.

[0198] 47. The method according to clause 46, further comprising: determining that an alignment timer for the communications device with respect to a second URP of the wireless communications network has expired; and based on determining that an alignment timer for the communications device with respect to the second URP has expired, transmitting, to the communications device, a third downlink transmission including an instruction to transmit a second random access preamble to the second URP.

[0199] 48. The method according to any of clauses 44-47, further comprising: receiving, via the first URP, the first random access preamble; determining an updated value of the first timing advance based on the first random access preamble; and transmitting, to the communications device, an indication of the updated value of the first timing advance.

[0200] 49. The method according to clause 46, wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes a preamble index.

[0201] 50. The method according to clause 44, wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes a reference signal identifier. 51. The method according to any of clauses 44-50, wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes an identifier for the first URP.

[0202] 52. The method according to clause 51 , wherein the identifier for the first URP is one or more of: an identifier of a time alignment group (TAG) in which the first URP is included; an index for the first URP; an identifier for a control resource set provided by the first URP; an identifier for a search space provided by the first URP; a radio network temporary identifier (RNTI); and / or a single bit within downlink control information.

[0203] 53. The method according to any of clauses 44-52, further comprising: receiving, via the first URP, a random access preamble from the communications device; and determining an updated value of the first timing advance based on the first random access preamble; and transmitting, to the communications device, an indication of the updated value of the first timing advance.

[0204] 54. The method according to clause 53, further comprising: receiving, via a second URP of the wireless access network, the first random access preamble from the communications device; and determining an updated value of a second timing advance for the second URP based on the first random access preamble received via the second URP; and transmitting, to the communications device, an indication of the updated value of the second timing advance.

[0205] 55. The method according to any of clauses 34-54, wherein the first transmission includes a random access preamble, and wherein the first time is the first reference timing

[0206] 56. The method according to any of clauses 34-55, further comprising: transmitting, to the communications device, an indication of the first reference timing.

[0207] 57. The method according to clause 56, wherein the TRP transmits the indication of the first reference timing via RRC signalling.

[0208] 58. The method according to clause 56 or 57, wherein the TRP transmits the indication of the first reference timing via one or more system information blocks (SIBs).

[0209] 59. The method according to any of clauses 56-58, wherein the TRP transmits the indication of the first reference timing via downlink control information.

[0210] 60. The method according to any of clauses 34-59, wherein the first reference timing is a received downlink slot timing for the TRP.

[0211] 61. The method according to any of clauses 34-60, wherein the TRP is configured to transmit signals to, and receive signals from the TRP via a backhaul communications link, and wherein the other TRP provides a secondary cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the other TRP when the communications device is located within the secondary cell provided by the other TRP, the secondary cell being smaller than, and located within, the cell provided by the TRP, and wherein the first reference timing is a received downlink slot timing for the other TRP of the wireless communications network.

[0212] 62. The method according to any of clauses 34-61 , wherein the first reference timing is a global satellite-based timing.

[0213] 63. The method according to any of clauses 34-62, wherein the uplink-only cell provided by the first URP is smaller than, and located within, the cell provided by the TRP. 64. The method according to any of clauses 34-63, wherein the first reference timing is predefined.

[0214] 65. A transmission and reception point (TRP) of a wireless communications network, the TRP comprising: a transceiver configured to transmit signals to and / or to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, wherein the transceiver is further configured to transmit signals to and / or to receive signals from a first uplink-only reception point (URP) of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; and a controller configured together with the transceiver to: receive, directly from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time; and receive, via the first URP, a second uplink transmission from the communications device, wherein the second uplink transmission is transmitted by the communications device at a second time, wherein the communications device determines the second time based on a first reference timing, and wherein the second time is different to the first time.

[0215] 66. Circuitry for a transmission and reception point (TRP) of a wireless communications network, the circuitry comprising: transceiver circuitry configured to transmit signals to and / or to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, wherein the transceiver is further configured to transmit signals to and / or to receive signals from a first uplink-only reception point (URP) of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; and controller circuitry configured together with the transceiver circuitry to: receive, directly from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time; and receive, via the first URP, a second uplink transmission from the communications device, wherein the second uplink transmission is transmitted by the communications device at a second time, wherein the communications device determines the second time based on a first reference timing, and wherein the second time is different to the first time.

[0216] 67. A method of operating an uplink-only reception point, URP, of a wireless communications network configured to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, wherein the URP is further configured to transmit signals to and / or to receive signals from a transmission and reception point, TRP, of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; wherein the method comprises: receiving, from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time, wherein the communications device determines the first time based on a first reference timing.

[0217] 68. The method according to clause 67, wherein the first uplink transmission is received according to a first timing advance, wherein the first timing advance is different to a second timing advance according to which the communications device is configured to transmit uplink transmissions to the TRP.

[0218] 69. The method according to clause 67 or 68, wherein the first uplink transmission includes a random access preamble.

[0219] 70. The method according to any of clauses 67-69, further comprising: transmitting, to the TRP via the backhaul communications link, the first uplink transmission received from the communications device.

[0220] 71. An uplink-only reception point (URP) of a wireless communications network, the URP comprising: a transceiver configured to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, and wherein the URP is further configured to transmit signals to and / or to receive signals from a transmission and reception point, TRP, of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink- only cell, the first URP being unable to transmit downlink transmissions to the communications device; and a controller configured together with the transceiver to: receive, from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time, wherein the communications device determines the first time based on a first reference timing.

[0221] 72. Circuitry for an uplink-only reception point (URP) of a wireless communications network, the circuitry comprising: transceiver circuitry configured to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, and wherein the URP is further configured to transmit signals to and / or to receive signals from a transmission and reception point, TRP, of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; and controller circuitry configured together with the transceiver circuitry to: receive, from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time, wherein the communications device determines the first time based on a first reference timing.

[0222] Accordingly, from one perspective there has been described: methods, communications devices, infrastructure equipment, and circuitry for allowing a communications device to determine when to transmit an uplink transmission to an uplink-only reception point (URP). The communications device identifies a reference timing, based on which the communications device determines when the uplink transmission should be transmitted. The reference timing may be a transmission time of the uplink transmission or may be used to calculate a timing advance for the uplink transmission.

[0223] REFERENCES

[0224] [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based radio access”, John Wiley and Sons, 2009.

[0225] [2] RWS-230248, “Views on Rel-19 MIMO / UL enhancements,” NTT DOCOMO, 3GPP TSG RAN Rel-19 workshop.

[0226] [3] TS 38.211, “Physical channels and modulation (Release 17)”, v17.3.0, 3GPP.

[0227] [4] TS 38.300, “NR and NG-RAN Overall description”, v.17.5.0, 3GPP.

Claims

CLAIMS1. A method of operating a communications device configured to transmit signals to and / or to receive signals from a first transmission and reception point, TRP, of a wireless communications network via a wireless radio interface provided by the wireless communications network, the method comprising: identifying a first reference timing for a first uplink-only reception point, URP, of the wireless communications network, the first URP being configured to transmit signals to, and receive signals from, the first TRP via a backhaul communications link, wherein the first TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the first TRP when the communications device is located within the cell provided by the first TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; wherein the method further comprises: determining, based on the identified first reference timing, a first time at which to transmit a first uplink transmission to the first URP; and transmitting the first uplink transmission to the first URP at the first time.

2. The method according to claim 1 , wherein determining the first time comprises identifying a first timing advance for the first URP relative to the first reference timing; and wherein the first uplink transmission to the first URP at the first time comprises transmitting the first uplink transmission to the first URP according to the determined first timing advance.

3. The method according to claim 1 , further comprising: receiving, from the first TRP, an indication of the first reference timing.

4. The method according to claim 3, wherein the communications device receives the indication of the first reference timing via RRC signalling.

5. The method according to claim 3, wherein the communications device receives the indication of the first reference timing via one or more system information blocks (SIBs).

6. The method according to claim 3, wherein the communications device receives the indication of the first reference timing via downlink control information.

7. The method according to claim 2, further comprising: transmitting, to the TRP, a second uplink transmission according to a second timing advance, wherein the second timing advance is different to the first timing advance.

8. The method according to claim 2, wherein identifying the first timing advance relative to the first reference timing comprises: receiving a first downlink transmission including an indication of a modification to the value of the first timing advance.

9. The method according to claim 8, wherein the first downlink transmission including the indication of the modification to the value of the first timing advance includes the first reference timing.

10. The method according to claim 2, further comprising: determining that an alignment timer for the communications device with respect to the first URP has expired; and based on determining that an alignment timer for the communications device with respect to the first URP has expired, transmitting, to the first URP, a random access preamble.

11. The method according to claim 10, wherein determining that an alignment timer for the communications device with respect to the first URP has expired comprises receiving a second downlink transmission instructing the communications device to transmit the random access preamble to the first URP.

12. The method according to claim 11 , wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes a preamble index.

13. The method according to claim 11 , wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes a reference signal identifier.

14. The method according to claim 11 , wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes an identifier for the first URP.

15. The method according to claim 14, wherein the identifier for the first URP is one or more of: an identifier of a time alignment group (TAG) in which the first URP is included; an index for the first URP; an identifier for a control resource set provided by the first URP; an identifier for a search space provided by the first URP; a radio network temporary identifier (RNTI); and / or a single bit within downlink control information.

16. The method according to claim 10, further comprising: based on determining that an alignment timer for the communications device with respect to the first URP has expired, transmitting, to a second URP of the wireless communications network, the random access preamble.

17. The method according to claim 10, further comprising: determining that an alignment timer for the communications device with respect to a second URP of the wireless communications network has expired; and based on determining that an alignment timer for the communications device with respect to the second URP has expired, transmitting, to the second URP, a random access preamble.

18. The method according to claim 1 , wherein the first uplink transmission includes a random access preamble, and wherein the first time is the first reference timing.

19. The method according to claim 1 , wherein the uplink-only cell provided by the first URP is smaller than, and located within, the cell provided by the first TRP.

20. The method according to claim 1 , further comprising: identifying a third timing advance for a second URP of the wireless communications network, the second URP being configured to transmit signals to, and receive signals from, the first TRP via a backhaul communications link, wherein the second URP provides an uplink- only cell for the communications device to transmit uplink transmissions to the second URP when the communications device is located within the uplink-only cell, the second URP being unable to transmit downlink transmissions; and transmitting a third uplink transmission to the second URP according to the determined third timing advance.21 . The method according to claim 20, further comprising: identifying a second reference timing for the third timing advance for the second URP; and wherein the communications device identifies the third timing advance relative to the second reference timing.

22. The method according to claim 21 , wherein the second reference timing is different to the first reference timing.

23. The method according to claim 21 , wherein the second reference timing is the same as the first reference timing.

24. The method according to claim 20, further comprising: receiving, from the TRP and in a downlink transmission scheduling an uplink transmission, an indication to transmit the uplink transmission to a particular one of the first and second URPs.

25. The method according to claim 20, further comprising: receiving, from the TRP and in a downlink transmission scheduling an uplink transmission, an indication to transmit the uplink transmission to both the first and second URPs.

26. The method according to claim 1 , wherein the first reference timing is predefined.

27. The method according to claim 1 , wherein the communications device is further configured to transmit signals to and / or to receive signals from a second TRP of the wireless communications network, the second TRP being configured to transmit signals to, and receive signals from the first TRP via a backhaul communications link, and wherein the second TRP provides a secondary cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the second TRP when the communications device is located within the secondary cell provided by the second TRP, the secondary cell being smaller than, and located within, the cell provided by the first TRP.

28. The method according to claim 27, wherein identifying the first reference timing comprises receiving, via the second TRP, the first reference timing.

29. The method according to claim 27, wherein the first reference timing is a received downlink slot timing for the second TRP.

30. The method according to claim 1 , wherein the first reference timing is a received downlink slot timing for the first TRP.31 . The method according to claim 1 , wherein the first reference timing is a global satellitebased timing.

32. A communications device comprising: a transceiver configured to transmit signals to and / or to receive signals from a first transmission and reception point (TRP) of a wireless communications network via a wireless radio interface provided by the wireless communications network, and wherein the transceiver is further configured to transmit signals to a first uplink-only reception point (URP) of the wireless communications network, the first URP being configured to transmit signals to, and receive signals from, the first TRP via a backhaul communications link, wherein the first TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the first TRP when the communications device is located within the cell provided by the first TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device, and a controller configured together with the transceiver to: identify a first reference timing for the first URP; determine, based on the identified first reference timing, a first time at which to transmit a first uplink transmission to the first URP; and transmit the first uplink transmission to the first URP at the first time.

33. Circuitry for a communications device, the circuitry comprising: transceiver circuitry configured to transmit signals to and / or to receive signals from a first transmission and reception point (TRP) of a wireless communications network via a wireless radio interface provided by the wireless communications network, and wherein the transceiver circuitry is further configured to transmit signals to a first uplink-only reception point (URP) of the wireless communications network, the first URP being configured to transmit signals to, and receive signals from, the first TRP via a backhaul communications link, wherein the first TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the first TRP when the communications device is located within the cell provided by the first TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device, andcontroller circuitry configured together with the transceiver circuitry to: identify a first reference timing for the first URP; determine, based on the identified first reference timing, a first time at which to transmit a first uplink transmission to the first URP; and transmit the first uplink transmission to the first URP at the first time.

34. A method of operating a transmission and reception point, TRP, of a wireless communications network configured to transmit signals to and / or to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, wherein the TRP is further configured to transmit signals to and / or to receive signals from a first uplink-only reception point, URP, of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; wherein the method comprises: receiving, directly from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time; and receiving, via the first URP, a second uplink transmission from the communications device, wherein the second uplink transmission is transmitted by the communications device at a second time, wherein the communications device determines the second time based on a first reference timing, and wherein the second time is different to the first time.

35. The method according to claim 34, wherein the first uplink transmission is received according to a first timing advance, and wherein the second uplink transmission is received according to a second timing advance, wherein the second timing advance is different to the first timing advance.

36. The method according to claim 35, wherein the second timing advance is applied relative to the first reference timing.

37. The method according to claim 35, further comprising: transmitting, to the communications device, an indication of a value of the second timing advance relative to the first reference timing.

38. The method according to claim 35, wherein the TRP is further configured to transmit signals to and / or to receive signals from a second URP of the wireless communications network via a backhaul communications link, wherein the second URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the second URP when the communications device is located within the uplink-only cell, the second URP being unable to transmit downlink transmissions, and wherein the method further comprises: receiving, via the second URP, a third uplink transmission from the communications device, wherein the third uplink transmission is received according to a third timing advance, wherein the third timing advance is different to the first timing advance.

39. The method according to claim 38, further comprising: transmitting, to the communications device, an indication of a second reference timing for the third timing advance for the second URP.

40. The method according to claim 39, wherein the second reference timing is the same as the first reference timing.41 . The method according to claim 39, wherein the second reference timing is different to the first reference timing.

42. The method according to claim 38, further comprising: transmitting, to the communications device and in a downlink transmission scheduling an uplink transmission, an indication of a particular one of the first and second URPs to which the communications device should transmit the uplink transmission.

43. The method according to claim 38, further comprising: transmitting, to the communications device and in a downlink transmission scheduling an uplink transmission, an indication for the communications device to transmit the uplink transmission to both the first and second URPs.

44. The method according to claim 35, further comprising: transmitting, to the communications device, a first downlink transmission including an indication of a modification to a value of the first timing advance.

45. The method according to claim 44, wherein the first downlink transmission including the indication of the modification to the value of the first timing advance includes one or more of the first and / or second reference timing.

46. The method according to claim 44, further comprising: determining that an alignment timer for the communications device with respect to the first URP has expired; and based on determining that an alignment timer for the communications device with respect to the first URP has expired, transmitting, to the communications device, a second downlink transmission including an instruction to transmit a first random access preamble to the first URP.

47. The method according to claim 46, further comprising: determining that an alignment timer for the communications device with respect to a second URP of the wireless communications network has expired; and based on determining that an alignment timer for the communications device with respect to the second URP has expired, transmitting, to the communications device, a third downlink transmission including an instruction to transmit a second random access preamble to the second URP.

48. The method according to claim 44, further comprising: receiving, via the first URP, the first random access preamble; determining an updated value of the first timing advance based on the first random access preamble; and transmitting, to the communications device, an indication of the updated value of the first timing advance.

49. The method according to claim 46, wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes a preamble index.

50. The method according to claim 44, wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes a reference signal identifier.

51. The method according to claim 44, wherein the second downlink transmission including the indication of the modification to the value of the first timing advance includes an identifier for the first URP.

52. The method according to claim 51 , wherein the identifier for the first URP is one or more of: an identifier of a time alignment group (TAG) in which the first URP is included;an index for the first URP; an identifier for a control resource set provided by the first URP; an identifier for a search space provided by the first URP; a radio network temporary identifier (RNTI); and / or a single bit within downlink control information.

53. The method according to claim 44, further comprising: receiving, via the first URP, a random access preamble from the communications device; and determining an updated value of the first timing advance based on the first random access preamble; and transmitting, to the communications device, an indication of the updated value of the first timing advance.

54. The method according to claim 53, further comprising: receiving, via a second URP of the wireless access network, the first random access preamble from the communications device; and determining an updated value of a second timing advance for the second URP based on the first random access preamble received via the second URP; and transmitting, to the communications device, an indication of the updated value of the second timing advance.

55. The method according to claim 34, wherein the first transmission includes a random access preamble, and wherein the first time is the first reference timing56. The method according to claim 34, further comprising: transmitting, to the communications device, an indication of the first reference timing.

57. The method according to claim 56, wherein the TRP transmits the indication of the first reference timing via RRC signalling.

58. The method according to claim 56, wherein the TRP transmits the indication of the first reference timing via one or more system information blocks (SIBs).

59. The method according to claim 56, wherein the TRP transmits the indication of the first reference timing via downlink control information.

60. The method according to claim 34, wherein the first reference timing is a received downlink slot timing for the TRP.

61. The method according to claim 34, wherein the TRP is configured to transmit signals to, and receive signals from the TRP via a backhaul communications link, and wherein the other TRP provides a secondary cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the other TRP when the communications device is located within the secondary cell provided by the other TRP, the secondary cell being smaller than, and located within, the cell provided by the TRP, and wherein the first reference timing is a received downlink slot timing for the other TRP of the wireless communications network.

62. The method according to claim 34, wherein the first reference timing is a global satellite-based timing.

63. The method according to claim 34, wherein the uplink-only cell provided by the first URP is smaller than, and located within, the cell provided by the TRP.

64. The method according to claim 34, wherein the first reference timing is predefined.

65. A transmission and reception point (TRP) of a wireless communications network, the TRP comprising: a transceiver configured to transmit signals to and / or to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, wherein the transceiver is further configured to transmit signals to and / or to receive signals from a first uplink-only reception point (URP) of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; and a controller configured together with the transceiver to: receive, directly from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time; andreceive, via the first URP, a second uplink transmission from the communications device, wherein the second uplink transmission is transmitted by the communications device at a second time, wherein the communications device determines the second time based on a first reference timing, and wherein the second time is different to the first time.

66. Circuitry for a transmission and reception point (TRP) of a wireless communications network, the circuitry comprising: transceiver circuitry configured to transmit signals to and / or to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, wherein the transceiver is further configured to transmit signals to and / or to receive signals from a first uplink-only reception point (URP) of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; and controller circuitry configured together with the transceiver circuitry to: receive, directly from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time; and receive, via the first URP, a second uplink transmission from the communications device, wherein the second uplink transmission is transmitted by the communications device at a second time, wherein the communications device determines the second time based on a first reference timing, and wherein the second time is different to the first time.

67. A method of operating an uplink-only reception point, URP, of a wireless communications network configured to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, wherein the URP is further configured to transmit signals to and / or to receive signals from a transmission and reception point, TRP, of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; wherein the method comprises:receiving, from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time, wherein the communications device determines the first time based on a first reference timing.

68. The method according to claim 67, wherein the first uplink transmission is received according to a first timing advance, wherein the first timing advance is different to a second timing advance according to which the communications device is configured to transmit uplink transmissions to the TRP.

69. The method according to claim 67, wherein the first uplink transmission includes a random access preamble.

70. The method according to claim 67, further comprising: transmitting, to the TRP via the backhaul communications link, the first uplink transmission received from the communications device.

71. An uplink-only reception point (URP) of a wireless communications network, the URP comprising: a transceiver configured to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, and wherein the URP is further configured to transmit signals to and / or to receive signals from a transmission and reception point, TRP, of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device to transmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; and a controller configured together with the transceiver to: receive, from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time, wherein the communications device determines the first time based on a first reference timing.

72. Circuitry for an uplink-only reception point (URP) of a wireless communications network, the circuitry comprising: transceiver circuitry configured to receive signals from a communications device via a wireless radio interface provided by the wireless communications network, and wherein the URP is further configured to transmit signals to and / or to receive signals from a transmission and reception point, TRP, of the wireless communications network via a backhaul communications link, wherein the TRP provides a cell for the communications device totransmit uplink transmissions to and receive downlink transmissions from the TRP when the communications device is located within the cell provided by the TRP, and wherein the first URP provides an uplink-only cell for the communications device to transmit uplink transmissions to the first URP when the communications device is located within the uplink-only cell, the first URP being unable to transmit downlink transmissions to the communications device; and controller circuitry configured together with the transceiver circuitry to: receive, from the communications device, a first uplink transmission, wherein the first uplink transmission is transmitted by the communications device at a first time, wherein the communications device determines the first time based on a first reference timing.

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