EP4662822A1

EP4662822A1 - Methods, communications devices, and network infrastructure equipment

Info

Publication number: EP4662822A1
Application number: EP24704170.0A
Authority: EP
Inventors: Shin Horng Wong; Yassin Aden Awad
Original assignee: Sony Europe BV; Sony Group Corp
Current assignee: Sony Europe BV; Sony Group Corp
Priority date: 2023-02-10
Filing date: 2024-02-08
Publication date: 2025-12-17
Also published as: WO2024165687A1

Abstract

Methods, communications devices, infrastructure equipment, and circuitry for overcoming collision between a PDCCH candidate and a non-downlink sub-band. A collision is detected and, in response to detecting the collision, the PDCCH candidate is modified. The PDCCH candidate can be modified by reducing the aggregation level of the PDCCH candidate, relocating resources of the PDCCH candidate in time and/or frequency, and/or altering an interleaving of the PDCCH candidate resources.

Description

METHODS, COMMUNICATIONS DEVICES, AND NETWORK INFRASTRUCTURE EQUIPMENT

The present application claims the Paris Convention priority of European patent application EP23156051.7, filed 10 February 2023, the contents of which are hereby incorporated by reference.

BACKGROUND

Field of Disclosure

The present disclosure relates to a communications device, network infrastructure equipment and methods of operating a communications device to receive data from a wireless communications network.

Description of Related Art

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

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.

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.

One example of a new service is referred to as Ultra Reliable Low Latency Communications (URLLC) services which, as its name suggests, requires that a data unit or packet be communicated with a high reliability and with a low communications delay. Another example of a new service is enhanced Mobile Broadband (eMBB) services, which are characterised by a high capacity with a requirement to support up to 20 Gb/s. URLLC and eMBB type services therefore represent challenging examples for both LTE type communications systems and 5G/NR communications systems.

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.

SUMMARY OF THE DISCLOSURE

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

According to a first aspect there is provided a method of operating a communications device configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a wireless radio interface provided by the wireless communications network, the method comprising: detecting a collision between one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space and a nondownlink sub-band of a timing slot, wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device; based on detecting the collision between the one or more PDCCH candidates and the non-downlink sub-band, modifying the one or more PDCCH candidates that collide with the non-downlink sub-band to overcome the collision between the one or more PDCCH candidates and the non-downlink sub-band.

According to a second aspect there is provided a method for an infrastructure equipment configured to transmit signals to and/or to receive signals from a communications device of a wireless communications network via a wireless radio interface provided by the wireless communications network, the method comprising: transmitting, to the communications device, an indication of one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space, the one or more PDCCH candidates indicating a first set of resources for the communications device to monitor for a PDCCH transmission; and based on detecting a collision between the one or more PDCCH candidates and a non-downlink sub-band of a timing slot, transmitting, for receipt by the communications device, a PDCCH using a second set of resources different to the first set of resources, the second set of resources having one or more modifications relative to the first set of resources, and wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device.

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

BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

Figure 3 is a schematic block diagram of an example infrastructure equipment and communications device which may be configured to operate in accordance with certain embodiments of the present disclosure;

Figure 4 illustrates an example division of system bandwidth into dedicated uplink and downlink sub-bands in Sub-band Full Duplex (SBFD);

Figure 5 illustrates additional examples of division of system bandwidth into dedicated uplink and downlink sub-bands in SBFD;

Figure 6 illustrates three possible Control Resource Sets (CORESETs), each occupying differing numbers of orthogonal frequency division multiplexing (OFDM) symbols and having differing numbers of Resource Element Groups (REGs) and Control Channel Elements (CCEs);

Figure 7 illustrates three possible CCE interleaver configurations for three CORESETS each having four CCEs;

Figure 8 illustrates two example Physical Downlink Control Channel (PDCCH) Search Spaces, each having multiple PDCCH candidates with differing aggregation levels;

Figure 9 illustrates an example of a collision between a PDCCH Search Space and a nondownlink sub-band of an SBFD slot;

Figure 10 illustrates an example of a CORESET which avoids collisions between a PDCCH Search Space and a non-downlink sub-band of an SBFD slot;

Figure 11 illustrates an example of a CORESET that is not aligned to the boundaries of an uplink sub-band of an SBFD slot;

Figure 12 illustrates an example of configuring multiple CORESETS with different RBs to avoid collisions between a PDCCH Search Space and a non-downlink sub-band of an SBFD slot;

Figure 13 illustrates an example approach for dynamically reducing the aggregation level of a PDCCH candidate to avoid collisions between a PDCCH candidate and a non-downlink subband of an SBFD slot; Figure 14 illustrates an example approach for dynamically relocating invalid CCEs in time;

Figure 15 illustrates an example approach for repeating invalid CCEs of a PDCCH candidate having invalid CCEs;

Figure 16 illustrates an example approach for dynamically relocating invalid CCEs in the frequency domain;

Figure 17 illustrates an example approach for dynamically reconfiguring a CORESET when a collision between a CORESET and an uplink sub-band of an SBFD slot;

Figure 18 illustrates an example approach for dynamically relocating a set of CCEs of a PDCCH candidate;

Figure 19 illustrates an example approach for dynamically relocating invalid REG bundles;

Figure 20 illustrates an example approach for dynamically changing interleaved CCEs to noninterleaved CCEs; and

Figure 21 illustrates an example approach for modifying a PDCCH candidate based on the presence of an uplink transmissions within a threshold period of time.

Figure 22 shows a flow diagram for a method for operating a communications device according to the present disclosure.

Figure 23 shows a flow diagram for a method for infrastructure equipment according to the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Long Term Evolution Advanced Radio Access Technology (4G)

Figure 1 provides a schematic diagram illustrating some basic functionality of a mobile telecommunications network / system 6 operating generally in accordance with LTE principles, but which may also support other radio access technologies, and which may be adapted to implement embodiments of the disclosure as described herein. Various elements of Figure 1 and certain aspects of their respective modes of operation are well-known and defined in the relevant standards administered by the 3GPP (RTM) body, and also described in many books on the subject, for example, Holma H. and Toskala A [1], It will be appreciated that operational aspects of the telecommunications networks discussed herein which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to the relevant standards and known proposed modifications and additions to the relevant standards.

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

Data is transmitted from base stations 1 to communications devices 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.

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

New Radio Access Technology (5G (NR))

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 25.

The elements of the wireless access network shown in Figure 2 may operate in a similar way to corresponding elements of an LTE network as described with regard to the example of Figure 1. It will be appreciated that operational aspects of the telecommunications network represented in Figure 2, and of other networks discussed herein in accordance with embodiments of the disclosure, which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to currently used approaches for implementing such operational aspects of wireless telecommunications systems, e.g. in accordance with the relevant standards.

The TRPs 10 of Figure 2 may in part have a corresponding functionality to a base station or eNodeB of an LTE network. Similarly, the communications devices 14 may have a functionality corresponding to the UE devices 4 known for operation with an LTE network. It will be appreciated therefore that operational aspects of a new RAT network (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be different to those known from LTE or other known mobile telecommunications standards. However, it will also be appreciated that each of the core network component, base stations and communications devices of a new RAT network will be functionally similar to, respectively, the core network component, base stations and communications devices of an LTE wireless communications network.

In terms of broad top-level functionality, the core network 20 connected to the new RAT telecommunications system represented in Figure 2 may be broadly considered to correspond with the core network 2 represented in Figure 1 , and the respective central units 40 and their associated distributed units 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.

It will further be appreciated that Figure 2 represents merely one example of a proposed architecture for a new RAT based telecommunications system in which approaches in accordance with the principles described herein may be adopted, and the functionality disclosed herein may also be applied in respect of wireless telecommunications systems having different architectures.

Thus, certain embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems 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.

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.

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.

As shown in Figure 3, the TRP 10 also includes a network interface 50 which connects to the DU 42 via a physical interface 16. The network interface 50 therefore provides a communication link for data and signalling traffic from the TRP 10 via the DU 42 and the CU 40 to the core network 20.

The interface 46 between the DU 42 and the CU 40 is known as the 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.

Full Duplex Time Division Duplex (FD-TDD)

NR/5G networks can operate using Time Division Duplex (TDD), where an entire frequency band or carrier is switched to either downlink or uplink transmissions for a time period and can be switched to the other of downlink or uplink transmissions at a later time period. Currently, TDD operates in Half Duplex mode (HD-TDD) where the gNB or UE can, at a given time, either transmit or receive packets, but not both at the same time. As wireless networks transition from NR to 5G-Advanced networks, a proposed new feature of such networks is to enhance duplexing operation for Time Division Multiplexing (TDD) by enabling Full Duplex operation in TDD (FD-TDD) [2], In FD-TDD, a gNB can transmit and receive data to and from the UEs at the same time on the same frequency band or carrier. In addition, a UE can operate either in HD-TDD or FD-TDD mode, depending on its capability. For example, when UEs are only capable of supporting HD-TDD, FD-TDD is achieved at the gNB by scheduling a downlink (DL) transmission to a first UE and scheduling an uplink (UL) transmission from a second UE within the same orthogonal frequency division multiplexing (OFDM) symbol (i.e. at the same time). Conversely, when UEs are capable of supporting FD-TDD, FD-TDD is achieved both at the gNB and the UE, where the gNB can simultaneously schedule this UE with DL and UL transmissions within the same OFDM symbol by scheduling the DL and UL transmissions at different frequencies (e.g. physical resource blocks (PRBs)) of the system bandwidth. A UE supporting FD-TDD requires more complex hardware than a UE that only supports HD-TDD. Development of current 5G networks is focused primarily on enabling FD-TDD at the gNB with UEs operating in HD-TDD mode.

Motivations for enhancing duplexing operation for TDD include an improvement in system capacity, reduced latency, and improved uplink coverage. For example, in current HD-TDD systems, OFDM symbols are allocated only for either a DL or UL direction in a semi-static manner. Hence, if one direction experiences less or no data, the spare resources cannot be used in the other direction, or are, at best, under-utilized. However, if resources can be used for DL data and UL data (as in FD-TDD) at the same time, the resource utilization in the system can be improved. Furthermore, in current HD-TDD systems, a UE can receive DL data, but cannot transmit UL data at the same time, which causes delays. If a gNB or UE is allowed to transmit and receive data at the same time (as with FD-TDD), the traffic latency will be improved. In addition, UEs are usually limited in the UL transmissions when located close to the edge of a cell. While the UE coverage at the cell-edge can be improved if more time domain resources are assigned to UL transmissions (e.g. repetitions), if the UL direction is assigned more time resources, fewer time resources can be assigned to the DL direction, which can lead to system imbalance. Enabling FD-TDD would help allow a UE to be assigned more UL time resources when required, without sacrificing DL time resources.

Sub-band Full Duplex (SBFD)

In some implementations, the system (i.e. UE/gNB) bandwidth, or Bandwidth Part (BWP) is divided into non-overlapping sub-bands 401-403 allocated to UL or DL, as shown in Figure 4, where simultaneous DL and UL transmissions may occur in different sub-bands 401-403, i.e. in different sets of frequency Resource Blocks (RB). This may be referred to as Sub-band Full Duplex (SBFD). While Figure 4 shows the system bandwidth as being divided into three subbands, substantially any number of sub-bands could be used. For example, the system bandwidth may be divided into four sub-bands, which may include two downlink sub-bands and two uplink sub-bands, however other sub-band arrangements are envisioned.

In some implementations, a guard sub-band 410 may be configured between UL and DL subbands 401-403. An example is shown in Figure 4, where a TDD system bandwidth is divided into three sub-bands 401 , 402, 403: Sub-band#1 401 , Sub-band#2 402 and Sub-band#3 403, such that Sub-band#1 401 and Sub-band#3 403 are used for DL transmissions whilst Sub- band#2 402 is used for UL transmissions. Guard sub-bands 410 are configured between DL Sub-band#3 403 and UL Sub-band#2 402 and between UL Sub-band#2 402 and DL Subband#! 401. The arrangement of sub-bands 401-403 shown in Figure 4 is just one possible arrangement of the sub-bands and other arrangements are possible, and guard bands may be used in substantially any sub-band arrangement.

SBFD may not necessarily be configured for all slots or OFDM symbols. That is, in some slots or OFDM symbols, there are may be no sub-bands and the slots/symbols may be either fully downlink or uplink, whilst in other slots/OFDM symbols SBFD may be configured where there are DL and U L sub-bands. Moreover, it should be appreciated that the sub-band format shown in Figure 4 is merely an example of a sub-band arrangement, and that other sub-band arrangements may be implements. For example, Figure 5 shows two examples of sub-band arrangements, where the size of the sub-bands may be different from one another. Furthermore, on the left-hand side of Figure 5 the UL sub-band is at the lower portion of the bandwidth whilst the DL sub-band is at the upper portion of the bandwidth. Conversely, on the right-hand side of Figure 5 the DL sub-band and UL sub-band are at the lower and upper portions of the bandwidth respectively.

Physical Downlink Control Channel (PDCCH) configuration

Downlink Control Information (DCI), such as a UL grant and a DL grant to schedule a PUSCH and PDSCH respectively, Group Common DCI that signals control information to multiple UEs such as slot format indicator (SFI), DL Pre-emption Indicators, and UL Pre-emption indicators, are carried by a Physical Downlink Control Channel (PDCCH). A UE may monitor for a PDCCH by blind decoding for the PDCCH in a periodically occurring PDCCH Search Space, where the PDCCH Search Space uses resources defined in a Control Resource Set (CORESET). The frequency and time physical resources in the downlink occupied by a PDCCH are configured in a CORESET. A UE can be configured with a maximum of 12 or 16 CORESETs per serving cell, where each CORESET contains one or more PDCCH Search Spaces. However, a UE can only monitor up to 3 CORESETs in a BWP.

In the time domain, the duration of a CORESET, Nc-symboi, can occupy up to 3 OFDM symbols and is RRC configured in the RRC parameter duration of the Control Resource Set Information Element (IE). The exact time location of the CORESET is dependent upon the time location of the PDCCH Search Spaces using the CORESET. In the frequency domain, the number of RBs, NC-RB, in a CORESET is configured via the RRC parameter frequencyDomainResources of the ControlResourceSet IE, which consists of a 45 bit bitmap where each bit represents 6 RBs. That is, the CORESET is configured in multiples of 6 RBs. A Resource Element Group (REG) is a unit in a CORESET which occupies one RB and one OFDM symbol. The number of REGs NREG in a CORESET is therefore: NREG = Nc-symboi ^x NC-RB- The REGs are indexed in time first followed by frequency and several contiguous indexed REGs can be bundled, where REGs in a bundle have the same precoding, which increases the number of reference signals (RS) for channel estimation. The possible REG bundle sizes are L_Bundie = {2, 6} for Nc-symboi = 1 or 2 and L_Bundie = {3, 6} for N_C-symboi = 3 and may be indicated in the RRC parameter reg- BundleSize of the ControlResourceSet IE.

Figure 6 shows three CORESETs 610(1)-(3) each with N_C-RB=24 RBS and N_C-s_ymboi = 1 , 2 and 3 OFDM symbols respectively. As such, the CORESETs 610(1)-(3) have 24, 48 and 72 REGs respectively. The REG bundle size in Figure 6 is L_Bundie=Q and they are shown in different shadings in each CORESET. A Control Channel Element (CCE) consists of 6 REGs where the CCE to REG mapping can be non-interleaved or interleaved. For a non-interleaved CCE, the REG bundle size L_Bundie = 6, that is, a CCE is an REG bundle and the CCEs are indexed in continuous manner. Using the example in Figure 6, the CORESETs 610(1)-(3) with Nc-symboi = 1 , 2 and 3 have a number of CCEs, NCCE = 4, 8 and 12 respectively.

The interleaver function for the CCE depends on the REG bundle size L_Bundie, the number of REGs NREG, and an interleaver size Rmterieave [3]. The possible interleaver size values are Rmterieave={2, 3, 6} and is RRC configured in parameter interleaverSize of ControlResourceSet IE. For L_Bundie=2 and 3, the REGs in the CCE are distributed in frequency to provide frequency diversity. Figure 7 shows three example CCE interleaver configurations for three CORESETs with NREG=24. The three CORESETs are configured with durations Nc-symboF{ , 2, 3}, bundle size L_Bundie={Q, 2, 3} and Interleaver size Rinteneave={2, 3, 2} respectively. For the CORESET with Nc-symboF^ , since L_Bundie=Q, the REGs in the CCEs are not distributed in frequency but the order of the CCE index is interleaved, i.e., to {CCEO, CCE2, CCE1 , CCE3}. For Nc-s_ymboi=2 and L_Bundie=2, each CCE is divided into 3 REG bundles, and they are distributed in frequency. Similarly, for N_C-symboi=3 and L_Bundie=3, each CCE is divided into 2 REG bundles, which are also distributed in frequency. PDCCH Search Space

A PDCCH Search Space is a set of resources in which a PDCCH may be carried and can be a Common Search Space (CSS) or UE Specific Search Space (USS). A CSS may be the same for all UEs, for example to schedule SIBs, Random Access Channel (RACH) signaling such as Random Access (RA) & Message 3 and paging, or for a group of UEs, for example indicate Slot Format Indicator (SFI), DL Pre-emption Indicator and UL Cancellation Indicator. Conversely, a USS is configured specifically for a particular UE and it is used for UL Grant, DL Grant and activation DCIs for SPS and CG-PUSCH. A UE can be configured with multiple CSS and USS, which can have different periodicities and starting offsets relative to a radio frame.

A PDCCH consists of one or more CCEs, where the number of CCEs in a PDCCH is the Aggregation Level (AL) of the PDCCH and has possible values of AL={1 , 2, 4, 8, 16}. Since a PDCCH with a higher AL uses more resources, it is more robust than a PDCCH with a lower AL. Variability in AL enables a gNB to efficiently schedule PDCCHs to UEs at different radio conditions by using the appropriate AL for the PDCCHs. The AL used by the gN B for a PDCCH is not signaled to the UE and as such the UE blind decodes for the PDCCH. In order to provide the gNB flexibility in scheduling the PDCCH AL, and without increasing the complexity for the UE in PDCCH blind decoding, a PDCCH Search Space that has a limited number of PDCCH candidates is used. The PDCCH candidates of a PDCCH Search Space are signaled to the UE, e.g. via RRC signaling, and the UE only attempts to blind decode for these PDCCH candidates. In other words, a PDCCH candidate is a set of specific time and frequency resources a UE monitors within a PDCCH Search Space.

A CORESET can contain one or more PDCCH Search Spaces, where each PDCCH Search Space has a set of PDCCH candidates which are defined by their AL and the CCEs they occupy. An example is shown in Figure 8, which shows a CORESET with duration N_C-symboi=2 OFDM symbols and occupies N_C-RB=24 RBS giving 48 REGs and 8 CCEs. For simplicity, we assume a non-interleaved CCE and the CCEs are labelled as CCEO to CCE7 (the REGs are not labelled), however it should be appreciated that the CCEs may be interleaved, as described above. The gNB configures two PDCCH Search Spaces using this CORESET, i.e. , USS#1 and USS#2 which can be for two different UEs. If the PDCCH candidates in each AL do not overlap, potentially this CORESET can have up to 15 PDCCH candidates. In this example, only a subset of possible PDCCH candidates are configured for USS#1 and USS#2. In USS#1 , 8 PDCCH candidates are configured labelled as C1-0 to C1-7, which consists of 4 x AL1 (C1-0 - C1-3), 2 x AL2 (C1-4 and C1-5), 1 x AL4 (C1-6) and 1 x AL8 (C1-7). USS#2 contains 6 PDCCH candidates labelled as C2-0 to C2-5, which consists of 3 x AL1 (C2-0 - C2-2), 2 x AL1 (C2-3 and C2-4) and 1 x AL4 (C2-5). The gNB can transmit two PDCCHs, one in each USS, as long as their CCEs do not overlap. That is, the gNB can transmit PDCCH candidate C1-6 in USS#1 to UE1 and transmit PDCCH candidate C2-3 in USS#2 to UE2, since PDCCH candidate C1-6 occupies CCE4, CCE5, CCE6 and CCE7 whilst PDCCH candidate C2-3 occupies CCE2 and CCE3, that is, their CCEs do not overlap. If the gNB transmits using PDCCH candidate C1-7 in USS#1 that occupies all the CCEs in the CORESET then it is not possible for the gNB to simultaneously transmit another PDCCH in USS#2, even to a different UE.

Overlap between a PDCCH Search Space and UL sub-band

In SBFD operation, it is expected that only a subset of slots would be configured with SBFD, whilst the other slots would be configured as DL, UL or flexible. For example, in Figure 9, in 5 consecutive slots, 3 slots labelled as Slot n+1 , n+2 and n+3 are configured as SBFD with an UL sub-band 930 in the middle of the BWP (between two DL sub-bands 920(1) and 920(2)), whilst Slot n and Slot n+4 are DL and UL slots respectively. This slot format pattern may be repeated for every 5 slots. A PDCCH Search Space 910 that occurs periodically may fall into an SBFD slot and may overlap with (i.e. be assigned to the same time and frequency resources as) an UL sub-band 930. For example, in Figure 9, a PDCCH Search Space 910 starting in Slot n has a periodicity of 2 slots and at Slot n+2, the PDCCH Search Space 910 overlaps with the UL sub-band 930. Since the UL sub-band 930 does not exist in some TDD systems, the PDCCH monitoring and blind decoding in the PDCCH Search Space 930 that overlaps with UL sub-band 930 is impacted.

In some systems, a PDCCH Search Space can be configured to avoid UL sub-bands or Guard sub-bands. This can be done in the time and/or frequency domain. In the time domain, the periodicity and time offset of the PDCCH Search Space can be configured such that it always falls onto a DL slot or DL OFDM symbols in a slot. However, this limits the flexibility of the gNB in configuring the PDCCH Search Space. Using the example in Figure 9, the PDCCH Search Space 910 needs to be configured to start in a DL slot, e.g., Slot n and has a periodicity that is a multiple of 5 slots. This reduces the scheduling opportunity of the gNB, as scheduling can only be performed every 5 slots, which may not be acceptable for URLLC traffic that has low latency. Furthermore, in such systems, a UE would be configured to monitor multiple PDCCH Search Spaces 910, which may be configured to support certain traffic, and as there is a limit on the number of blind decodings a UE can perform within a slot, these multiple PDCCH Search Spaces may not all be configured within the single DL slot. Accordingly, limiting the PDCCH Search Space to DL-only slots would impact the existing performance of the UE.

In the frequency domain, if the UL sub-band location is fixed, then the CORESET can be configured to avoid overlapping the UL sub-band, so that the PDCCH Search Spaces within this CORESET do not collide with the UL sub-band. Since the RRC parameter frequencyDomainResources that configures the frequency resource of the CORESET is a 45 bit bitmap, the CORESET can be configured to avoid overlapping the UL sub-band. An example is shown in Figure 10, where a CORESET 1010 (i.e. PDCCH Search Space) is configured with discontinuous RBs 1010(1 )-(4) to avoid the UL sub-band 930 in the middle of the BWP, regardless of whether the UL sub-band 930 exists or not in a slot. That is, Slot n+2 includes two downlink sub-bands 920(1), 920(2) and an uplink sub-band 930, and as such the discontinuous sections 1010(3)-(4) of the CORESET 1010 avoid the UL sub-band 930. However, this discontinuity in the CORESET 1010 occurs for all instances of that CORESET 1010. As such, in Slot n, which is configured fully for DL, the CORESET 1010 includes discontinuous section 1010(1 )-(2), despite the UL sub-band 930 not being present in Slot n. The consequence of this approach is that the CORESET 1010 underutilizes the available DL resources in slots that are fully DL (e.g. Slot n), as shown in Figure 10. That is, the bits in the 45 bit bitmaps corresponding to the UL sub-band 930 are set to “0” to avoid the UL sub-band and so cannot be used to carry PDCCH, and this is the case for all instances of the CORESET 1010. As such, this configuration assumes that the UL sub-band and Guard sub-band locations do not change dynamically.

In addition, since the RRC parameter frequencyDomainResources has a granularity of 6 RBs, the CORESET may not align with the UL sub-band or Guard sub-band boundaries if the RBs occupied by the UL sub-band and Guard sub-band are not multiples of 6 RBs. This may cause the CORESET to partially overlap with the UL sub-band or Guard sub-band to leave residual RBs that cannot be used for the CORESET/PDCCH Search Space. An example is shown in Figure 11 , where the RBs configured for a CORESET/PDCCH Search Space 1110 are discontinuous to avoid the UL sub-band 930 and Guard sub-band 940 in the middle of the BWP, as discussed above with respect to Figure 10. Here the UL sub-band 930 and Guard sub-band 940 boundaries are not aligned with the CORESET/PDCCH Search Space 1110 causing some RBs of the CORESET/PDCCH Search Space 1110 to overlap with the upper portion of the UL sub-band 930 and the upper Guard sub-band 940. The lower discontinuous portion of the CORESET/PDCCH Search Space 1110 leaves a residual RB which does not overlap with the UL sub-band 930 or the Guard sub-band 940, but nevertheless falls outside the CORESET/PDCCH Search Space 1110 due to the granularity of the CORESET/PDCCH Search Space 1110.

Another approach to avoid collision/overlap between an UL or Guard sub-band CORESET/PDCCH Search Space is to over-configure the number of CORESETs and PDCCH Search Spaces for the same service, so that one set of CORESETs and PDCCH Search Spaces is used in DL slots/symbols whilst another set is used in SBFD slots/symbols. An example is shown in Figure 12, where a slot format pattern of 5 slots consisting of a DL slot followed by 3 SBFD slots and ends with an UL slot is repeated. Two CORESETs, CORESET#1 1210 and CORESET#2 1215 are configured, where CORESET#1 1210 is used in DL slot and CORESET#2 1215 is used in SBFD slots. CORESET#2 1215 has discontinuous RBs to avoid the middle UL sub-band in the BWP. Two PDCCH Search Spaces are configured, where a 1^st PDCCH Search Space uses CORESET#1 1210 and a 2^nd PDCCH Search Space uses CORESET#2 1215. The 1^st PDCCH Search Space starts in a DL slot, e.g., Slot n and has periodicity Pi = 5 slots thereby occurring only in DL slots whilst the 2^nd PDCCH Search Space starts in an SBFD slot, e.g., Slot n+2 with periodicity P₂ = 5 such that it occurs only in SBFD slots. Hence, by over-configuring the number of CORESETs and PDCCH Search Spaces, the PDCCH Search Spaces avoid the UL Sub-band.

Although a UE can be configured with up to 15 CORESETs per carrier, it is limited to 3 CORESETs per BWP. Hence, over-configuring the number of CORESETs and PDCCH Search Spaces uses up the limited number of CORESETs, which may not be feasible if the UE already uses all the 3 CORESETs to support its required services. Furthermore, this approach assumes that the UL and Guard sub-bands are semi-static and cannot change dynamically.

Dynamic change of PDCCH candidates

The present inventors have identified an approach for addressing potential collisions between PDCCH Search Spaces and UL sub-bands that does not reduce PDCCH occasions, and is capable of utilizing the resources of DL slots without requiring over-configuring the number of CORESETs to support the required services, as well as adapt to dynamic changes to UL subbands.

According to the present disclosure, there is provided a method of operating a communications device configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a wireless radio interface provided by the wireless communications network, the method comprising: detecting a collision between one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space and a non-downlink sub-band, wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device; based on detecting the collision between the one or more PDCCH candidates and the non-downlink sub-band, modifying the one or more PDCCH candidates that collide with the non-downlink sub-band to overcome the collision between the one or more PDCCH candidates and the non-downlink sub-band. As such, the PDCCH candidates in a PDCCH Search Space are dynamically modified to adapt to changes in slot structure. In other words, the PDCCH candidates change to adapt the presence of an UL or Guard sub-band. As the PDCCH candidates are modified only if the slot structure changes, this approach is suitable for implementations where the time and frequency locations of the UL sub-band and Guard sub-band can change dynamically.

PDCCH candidates with CCEs colliding with invalid RBs may be modified. That is, CCEs colliding with invalid RBs may not be usable by the gNB, and as such the PDCCH candidate including these CCEs is affected. As a consequence, an invalid CCE is a CCE that collides fully or partially with one or more invalid RBs (i.e. has one or more REGs that overlap with a non-downlink sub-band). Moreover, invalid RBs may be defined as RBs that are not in a DL sub-band, i.e., RBs in an UL sub-band or a Guard sub-band. That is invalid RBs are RBs that are not used for DL transmissions. Alternatively, invalid RBs may be defined as RBs in an UL sub-band, i.e., RBs used for UL transmissions. In such cases, CCEs colliding with a Guard sub-band are not affected. This is beneficial for cases where the UE is not aware of the locations of the Guard sub-bands (i.e. the gNB manages the Guard sub-bands via scheduling that is not signaled to the UE). In this case, the UE would assume that the RBs occupied by the Guard sub-band contains a DL transmission even if nothing is transmitted there.

In an example teaching of the disclosure, the modifications or changes to the PDCCH candidates includes reducing the Aggregation Level (AL) of the PDCCH candidate. An example is shown in Figure 13, where a CORESET with duration of Nc-symboi = 2 OFDM symbols and NC-RB = 24 RBs, thereby having NREG=48 REGS, overlaps partially with an UL sub-band and Guard sub-band, as shown by the shading of Figure 13. A PDCCH Search Space with 7 PDCCH candidates (labelled as CO to C6) uses this CORESET, and consequently some of its PDCCH candidates overlap with invalid RBs (i.e. RBs which fall within a non-DL sub-band), where in this example invalid RBs are the RBs in the UL sub-band and Guard sub-band. Here, CCEO, CCE1 and CCE2 of the CORESET/PDCCH Search Space overlap with invalid RBs, and are thus invalid CCEs, causing PDCCH candidates CO, C1 , C3, C5 and C6 to be affected. Using this example, the ALs of these PDCCH candidates (CO, C1 , C3, C5 and C6) are reduced. For example, the AL for PDCCH candidate C6 is reduced from AL=8 to AL=5, since 3 of its CCEs (CCEO, CCE1 , CCE2) are invalid. In other words, the AL of the PDCCH candidates are reduced to remove invalid CCEs from the PDCCH candidates. This recognizes that the PDCCH consists of one or more CCEs and that if a subset of CCEs contributing to a PDCCH candidate are invalid, then these CCEs can be discounted from that PDCCH candidate thereby reducing its AL.

In some examples, the said reduction in AL reduces to the nearest valid AL. That is, the specifications may define only a limited set of possible ALs, i.e. AL={1 , 2, 4, 8} and PDCCH encoding/decoding may be based on these defined ALs. Using the example in Figure 13, PDCCH candidates C3, C5 and C6 would have their ALs reduced from 2 to 1 , 4 to 1 and 8 to 4 respectively. Furthermore, in some examples a PDCCH candidate is dropped (i.e. not used) if the number of invalid CCEs in that PDCCH candidate exceeds a threshold, Tmvaiid-ccE. The threshold Tmvaiid-ccE, can be fixed in the specifications or signaled to the UE (e.g. via RRC signaling). A UE does not need to consider (i.e. monitor) a dropped PDCCH candidate in a PDCCH Search Space, thereby reducing the number of blind PDCCH decodings. In other examples, the threshold Tmvaiid-ccE may be half the AL of the PDCCH candidate. Using the example in Figure 13, PDCCH candidate C5 has AL=4 and 3 out of 4 of its CCEs are invalid, i.e., more than half of its CCEs are invalid. Using this embodiment, PDCCH candidate C5 is dropped. In other words, if the AL of a PDCCH candidate is reduced by more than 1 valid level, e.g., AL 8 to AL 2, or AL 4 to AL 1 , then that PDCCH candidate is dropped. This recognizes that the AL of a PDCCH candidate determines the robustness of the PDCCH and if its AL is reduced too much than it may no longer be able to support its targeted coverage, and therefore is dropped.

In other examples, the threshold Ti_nvaiid-ccE may be the number of invalid CCEs, such that the AL of the PDCCH candidate cannot be reduced to the nearest valid AL. That is, if an AL=1 PDCCH candidate has an invalid CCE, then that PDCCH candidate cannot further reduce its AL and is therefore dropped. Using the example in Figure 13, PDCCH Candidate CO and C1 are dropped since they cannot further reduce the number of AL of their PDCCH. In some examples, the threshold Tmvaiid-ccE = 1 , i.e., if any of the CCEs in a PDCCH candidate is invalid, that PDCCH candidate is dropped.

In other examples, if of one or more modified PDCCH candidates cause duplicate PDCCH candidates, then the duplicate candidates are dropped such that only one remains. For example in Figure 13, PDCCH candidates C5 and C3 are reduced to AL=1 , occupying CCE3. That is, PDCCH candidate C5 and C3 are duplicates of each other. In this example, one of the modified candidates is dropped, e.g. modified PDCCH candidate C5 is dropped and modified PDCCH candidate C3 remains.

Instead of abandoning an invalid CCE, thereby reducing the AL of a PDCCH, the invalid CCE can be relocated to another resource in the time domain. That is, in some examples, the invalid CCEs may be relocated (or replaced) with valid CCEs in the time domain. An example is shown in Figure 14, where a PDCCH Search Space resides in a CORESET consisting of 8 CCEs labelled as CCEO to CCE7. The CORESET overlaps partially with UL sub-band and Guard sub-band. In this example, we assume that only RBs in UL sub-bands are invalid RBs and here CCEO and CCE1 are invalid CCEs. As per this example, the invalid CCEs are moved in time to other OFDM symbols, and in this example CCEO and CCE1 are moved to the 5^th and 6^th OFDM symbol of the slot. Note that even though only some of the REGs of CCE1 are invalid, CCE1 is deemed to be an invalid CCE, and as such the entire CCE is relocated.

In some examples, the PDCCH candidates with invalid CCEs are repeated in time. That is, the AL of the PDCCH candidate is not reduced, and instead the invalid CCEs are allowed to remain in the PDCCH candidate (although they will never carry a PDCCH transmission) and a number of CCEs equal to the number of invalid CCEs are added to the PDCCH candidate at a later time. For example, in Figure 14 two CCEs (corresponding to invalid CCEO and CCE1) are included in the PDCCH candidate at a later point in time. This may be later in the same slot as the original PDCCH candidate, or may be in a different slot.

In some examples, the movement of invalid CCEs may include reducing the AL of the PDCCH candidate and adding a number of CCEs to the PDCCH candidate at a later point in time. In other words, the CCEs may be relocated, rather than repeated. Furthermore, as shown in Figure 14, the repeated or relocated CCEs may be located at different frequency resources (i.e. DL resources). Alternatively, the repeated or relocated CCEs may be located at the same frequency resources, but at a later time when the frequency resources for the CCEs are allocated to DL resources (e.g. in a different slot, or in a later OFDM symbol of the same slot).

In some examples, the AL of PDCCH candidates with invalid CCEs are firstly reduced to the nearest valid AL, i.e., halved, and then the reduced AL PDCCH candidate is repeated. This example compensates for the loss of a PDCCH candidate with reduced AL, by repetitions. An example is shown in Figure 15, where a PDCCH Search Space resides in a CORESET of 8 CCEs and 2 of its CCEs, CCEO and CCE1 are invalid. Here, a PDCCH candidate with AL=4 occupies CCEO, CCE1 , CCE2 and CCE3 and, since CCEO and CCE1 are invalid, using a previous example, the PDCCH candidate AL is reduced to AL=2. Using this example, a PDCCH of AL=2 is provided in time which acts as a repetition of the impacted PDCCH candidate. Hence, the PDCCH candidate that has reduced its AL from AL=4 to AL=2 is able to compensate its loss via repetition of the PDCCH of AL=2. It should be appreciated that although the impacted PDCCH candidate is repeated once (i.e. occurs on two occasions), other number of repetitions can be used in this embodiment.

In some cases, the time resources to which the invalid CCEs are to be relocated can be signaled to the UE (e.g. via RRC signaling) or defined in the specifications. Furthermore, the number of repetitions of a PDCCH candidate with invalid CCEs can be signaled to the UE (e.g. via RRC signaling) or defined in the specifications.

In some examples, invalid CCEs may be relocated or replaced in the frequency domain but not the time domain. An example is shown Figure 16, where a CORESET partially overlaps the UL sub-band in a slot. The invalid CCEs are relocated to the bottom portion of the DL sub-band. The frequency resources to which the invalid CCEs are to be relocated can be signaled to the UE (e.g. via RRC signaling) or defined in the specifications. In some implementations a frequency offset may be configured or predefined for the relocation of invalid CCEs. If some CCEs of the original CORESET overlap partially with an UL sub-band and or Guard sub-band, then the UE may apply a second CORESET that is different than the first CORESET, such that the second CORESET does not collide with UL sub-band and or Guard sub-band as shown on Figure 17. The second CORESET is pre-configured for the UE, and it is only used when collision occurs. As discussed above, in some examples both the time and frequency resources for invalid CCEs may be modified (i.e. the CCEs are moved in both time and frequency). The time and frequency resources for relocation of invalid CCEs can be signaled to the UE (e.g. via RRC signaling) or defined in the specifications.

In some examples, if one or more CCEs in a set of CCEs are invalid, the entire set of CCEs are relocated in time and/or frequency. That is, CCEs may be arranged in sets, as shown in Figure 18. These sets of CCEs may or may not overlap one another, where if a CCE belongs to two or more sets of CCEs, these sets of CCEs are said to have overlapping CCEs. In Figure 18, the sets of CCEs do not overlap and a CORESET with 8 CCEs labelled as CCEO to CCE7 is divided into two sets of CCEs: Set 1 = {CCEO, CCE1 , CCE2, CCE3} and Set 2 = {CCE4, CCE5, CCE6, CCE7}. CCEO and CCE1 are invalid and hence in this example, all the CCEs in Set 1 are relocated to another resource (in time and/or frequency). In some implementations, the number and/or size of the CCE sets may be dependent upon the number of invalid CCEs. For example, if the number of invalid CCEs is less than half of the total CCEs, the CCEs in the CORESET may be divided into two equal sets. Conversely, if the number of invalid CCEs is more than half the total of CCEs, the CCEs in the CORESET may be divided into 4 equal sets. In some cases, each relocated CCE set may be a repetition of a CCE set that is not relocated. Using the example shown in Figure 18, the relocated Set 1 becomes a repetition of the un-relocated Set 2 (i.e. uses the same set of frequency resources as Set 2). The PDCCH candidates in Set 2 may then be changed using one of the previous embodiments. For example, the AL of the PDCCH candidates with the relocated CCEs may be reduced to the nearest valid AL.

While the foregoing discussion has concerned the relocation or repetition of invalid CCEs, collisions may be addressed at the REG level. That is, REGs (i.e. REG bundles) that collide with invalid RBs may be repeated or relocated to other time and/or frequency resources. This recognizes that for interleaved CCEs, it may not be practical to move an entire CCE if only a portion of its REG bundles are affected. An example is in Figure 19, showing a CORESET with 4 interleaved CCEs, CCEO, CCE1 , CCE2 and CCE3. REGs 1 to 10 (which include REGs belonging to each of CCEs 1-4, collide with invalid RBs and are therefore themselves invalid. As per this example, the impacted REGs, or the REG bundles are relocated in time and frequency, thereby ensuring all the CCEs can be used for a PDCCH candidate. As such, it should be appreciated that the examples of the present disclosure may be carried out at the level of individual REGs or REG bundles, as well as at the CCE, CCE set or PDCCH candidate level.

The above examples have primarily modified a PDCCH candidate by modifying the time/frequency resources of the REGs/CCEs, or by discarding/dropping invalid REGs/CCEs. However, the PDCCH candidate may be modified to avoid a collision in other ways in addition to those described above. For example, a CORESET with interleaved CCEs may be changed to non-interleaved CCEs, if at least a subset of its CCEs is invalid. An example is shown in Figure 20, where a CORESET has 4 interleaved CCEs labeled as CCEO, CCE1 , CCE2 and CCE4. As shown in the left-hand side of Figure 20, REGs 1 to 10 collide with invalid RBs (RBs in an UL or Guard sub-band) and consequently all the CCEs in the CORESET are invalid (as they contain invalid REGs). According to the present example, the CCEs may be modified to be non-interleaved CCEs. As shown in the right-hand side of Figure 20, this reduces the number of invalid CCEs from 4 (i.e. , all of them) to only 2 (i.e., CCEO and CCE1). Accordingly, only CCEO and CCE1 require further modification to avoid a collision (for example in the ways described above). This recognizes that the invalid RBs from the UL sub-band and/or Guard sub-band are contiguous and will collide with a contiguous set of REGs, but that the REGs of interleaved CCEs are not contiguous (i.e. they are distributed), and hence a comparatively small number of REGs colliding with invalid RBs may impact a large number of CCEs.

It should be appreciated that all of the embodiments described herein can be implemented individually or in combination with one another. For example, a reduction in AL of a PDCCH candidates with invalid CCEs can be combines with changing interleaved CCEs to noninterleaved CCEs of a CORESET. Furthermore, it should be appreciated that, upon detecting a collision between one or more REGs of PDCCH candidate and a non-DL sub-band, the PDCCH candidate may be modified only if other additional conditions are met.

For example, PDCCH candidates with invalid CCEs in a CORESET may only be modified if there are UL transmissions scheduled for the UE within a time window OUL (e.g. a particular number of OFDM symbols) after the end of that CORESET. An example is shown in Figure 21 , where a CORESET with Nc-symboi = 2 OFDM symbols starts at the beginning of a slot, and it partially overlaps an UL sub-band. As per this example, since there is no UL transmission within OUL OFDM symbols after the end of that CORESET, the PDCCH candidates with invalid CCEs are not changed. The UE may then blindly decode for a PDCCH using the original PDCCH candidates in the PDCCH Search Space. This recognizes that if there are no UL transmissions scheduled for the UE, the gNB can perform DL transmissions on the RBs in the UL sub-band. That is, the gNB may transmit a PDCCH with CCEs in the UL sub-band of the CORESET. Conversely, if the PUSCH were located within window OUL, the UE may determine that the gNB will not transmit a PDCCH using the RBs in the UL sub-band and may modify the PDCCH candidate to avoid any collision. The value of OUL may be, for example, the timing advance offset applied by the UE for UL transmissions or the value of OUL is RRC signaled or defined in the specifications.

Figure 22 shows a flow diagram for a method 2200 for operating a communications device according to the present disclosure. The method 2200 includes a step 2210 of detecting a collision between one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space and a non-downlink sub-band of a timing slot, wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a nondownlink sub-band for the communications device. The method then includes a step 2220 of, based on detecting the collision between the one or more PDCCH candidates and the nondownlink sub-band, modifying the one or more PDCCH candidates that collide with the nondownlink sub-band to overcome the collision between the one or more PDCCH candidates and the non-downlink sub-band.

Figure 23 shows a flow diagram for a method 2300 for infrastructure equipment according to the present disclosure. The method 2300 includes a step 2310 of transmitting, to the communications device, an indication of one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space, the one or more PDCCH candidates indicating a first set of resources for the communications device to monitor for a PDCCH transmission. The method then includes a step 2320 of based on detecting a collision between the one or more PDCCH candidates and a non-downlink sub-band of a timing slot, transmitting, for receipt by the communications device, a PDCCH using a second set of resources different to the first set of resources, the second set of resources having one or more modifications relative to the first set of resources, and wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device.

Thus, from one perspective, there has now been described methods, communications devices, infrastructure equipment, and circuitry for overcoming collision between a PDCCH candidate and a non-downlink sub-band. A collision is detected and, in response to detecting the collision, the PDCCH candidate is modified. The PDCCH candidate can be modified by reducing the aggregation level of the PDCCH candidate, relocating resources of the PDCCH candidate in time and/or frequency, and/or altering an interleaving of the PDCCH candidate resources.

Further examples of feature combinations taught by 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 an infrastructure equipment of a wireless communications network via a wireless radio interface provided by the wireless communications network, the method comprising: detecting a collision between one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space and a non-downlink sub-band of a timing slot, wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device; and based on detecting the collision between the one or more PDCCH candidates and the non-downlink sub-band, modifying the one or more PDCCH candidates that collide with the non-downlink sub-band to overcome the collision between the one or more PDCCH candidates and the nondownlink sub-band.

2. The method according to clause 1 , wherein the PDCCH search space includes a control resource set (CORESET) comprising a set of REGs for monitoring for PDCCH transmissions, and wherein the one or more PDCCH candidates are each a set of one or more control channel elements (CCEs) which the communications device is configured to monitor for PDCCH transmissions, wherein the one or more CCEs each comprise a plurality of REGs of the set of REGs included in the CORESET.

3. The method according to clause 1 or clause 2, wherein the non-downlink sub-band is an uplink sub-band and/or a guard sub-band. 4. The method according to clause 3, wherein the non-downlink sub-band is an uplink sub-band.

5. The method according to any preceding clause, wherein modifying the one or more PDCCH candidates includes reducing an aggregation level of the one or more PDCCH candidates, wherein the aggregation level is a number of control channel elements (CCEs) in a PDCCH candidate.

6. The method according to clause 5, wherein reducing the aggregation level comprises reducing the aggregation level to a nearest aggregation level included in a set of predefined aggregation levels.

7. The method according to any of clauses 5-6, wherein reducing the aggregation level comprises dropping the one or more PDCCH candidates based on a number of invalid REGs or CCEs in the PDCCH candidate exceeding a predetermined threshold.

8. The method according to clause 7, wherein the predetermined threshold is half an original aggregation level of the one or more PDCCH candidates.

9. The method according to clause 7, wherein the predetermined threshold is a minimum aggregation level in a set of predefined aggregation levels.

10. The method according to clause 7, or clause 9, wherein the predetermined threshold is 1 CCE.

11. The method according to any of clauses 4-6, wherein modifying the one or more PDCCH candidates further comprises dropping one of two or more duplicate PDCCH candidates, the duplicate PDCCH candidates being formed by the reduction of the aggregation level.

12. The method according to clause 11 , where the duplicate PDCCH candidates have the same aggregation level and use the same CCEs.

13. The method according to any preceding clause, wherein modifying the one or more PDCCH candidates includes relocating the one or more invalid REGs of the one or more PDCCH candidates in the time and/or frequency domains.

14. The method according to clause 13, wherein relocating the one or more invalid REGs comprises relocating the one or more invalid REGs in a time domain.

15. The method according to clause 14, wherein relocating the one or more invalid REGs in a time domain comprises removing one or more REGs from the PDCCH candidate and repeating the one or more removed REGs in the time domain.

16. The method according to clause 14 or 15, wherein relocating the one or more invalid REGs in the time domain comprises repeating the one or more invalid REGs in the time domain.

17. The method according to clause 16, wherein repeating the one or more invalid REGs in the time domain comprises repeating one or more invalid CCEs, including the one or more REGs, in the time domain.

18. The method according to clause 17, wherein repeating the one or more invalid CCEs in the time domain comprises repeating the one or more PDCCH candidates in the time domain. 19. The method of any of clauses 16-18, further comprising receiving signalling indicating a number of repetitions for the one or more repeated REGs.

20. The method according to any of clauses 14-19, further comprising receiving signalling indicating time resources in which the relocated REGs are to be located.

21. The method according any of clauses 13-20, wherein modifying the one or more PDCCH candidates includes relocating the REGs in a frequency domain.

22. The method according to clause 21 , wherein frequency resources to which the one or more invalid REGs are to be relocated are either indicated in signalling received by the communications device or predefined.

23. The method according to any of clause 21 or 22, wherein a frequency offset for the one or more REGs is either indicated in signalling received by the communications device or predefined.

24. The method according to any of clauses 21-23, wherein relocating the REGs in the frequency domain comprises reconfiguring a CORESET for the PDCCH search space.

25. The method according to any of clauses 13-24, wherein relocating the one or more invalid REGs comprises relocating one or more invalid CCEs, wherein the one or more invalid CCEs each comprise one or more invalid REGs.

26. The method according to clause 25, wherein modifying the one or more PDCCH candidates comprises relocating a set of multiple CCEs, the set of CCEs including one or more invalid CCEs.

27. The method according to clause 26, wherein a CORESET for the PDCCH search space includes a plurality of non-overlapping sets of CCEs.

28. The method according to any of clauses 26 or 27, wherein a number of sets of CCEs in the CORESET is based on a number of invalid CCEs.

29. The method according to any of clauses 27-28, wherein the CORESET includes a first set of CCEs and a second set of CCEs, wherein the first set of CCEs are relocated in the time domain and relocated in the frequency domain to the same frequency resources as the second set of CCEs.

30. The method according to any preceding clause, wherein the CORESET for the PDCCH search space is an interleaved CORESET including interleaved CCEs, and wherein modifying the one or more PDCCH candidates comprises changing the interleaved CORESET to a noninterleaved CORESET.

31. The method according to any preceding clause, wherein the one or more PDCCH candidates are modified based on whether any uplink transmissions are scheduled to occur within a fixed time period of the PDCCH search space.

32. The method according to clause 31 , wherein the fixed time period is a timing advance offset applied by the communications device for uplink transmissions.

33. The method according to clause 31 , wherein the fixed time period is either indicated in signalling received by the communications device or predefined.

34. A communications device, the communications device comprising: a transceiver configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network and/or one or more other communications devices, and a controller configured in combination with the transceiver to: detect a collision between one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space and a non-downlink sub-band of a timing slot, wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device; and based on detecting the collision between the one or more PDCCH candidates and the non-downlink sub-band, modify the one or more PDCCH candidates that collide with the non-downlink sub-band to overcome the collision between the one or more PDCCH candidates and the non-downlink sub-band.

35. Circuitry for a communications device comprising: transceiver circuitry configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network and/or one or more other communications devices, and controller circuitry configured in combination with the transceiver to: detect a collision between one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space and a non-downlink sub-band of a timing slot, wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device; based on detecting the collision between the one or more PDCCH candidates and the nondownlink sub-band, modify the one or more PDCCH candidates that collide with the nondownlink sub-band to overcome the collision between the one or more PDCCH candidates and the non-downlink sub-band.

36. A method for an infrastructure equipment configured to transmit signals to and/or to receive signals from a communications device of a wireless communications network via a wireless radio interface provided by the wireless communications network, the method comprising: transmitting, to the communications device, an indication of one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space, the one or more PDCCH candidates indicating a first set of resources for the communications device to monitor for a PDCCH transmission; and based on detecting a collision between the one or more PDCCH candidates and a non-downlink sub-band of a timing slot, transmitting, for receipt by the communications device, a PDCCH using a second set of resources different to the first set of resources, the second set of resources having one or more modifications relative to the first set of resources, and wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device.

37. The method according to clause 36, wherein the first set of resources is indicated by a control resource set (CORESET) comprising a set of REGs for monitoring for PDCCH transmissions, and wherein the one or more PDCCH candidates are each a set of one or more control channel elements (CCEs) for monitoring by the communications device for PDCCH transmissions, wherein the one or more CCEs each comprise a plurality of REGs of the set of REGs included in the CORESET.

38. The method according to clause 36 or clause 37, wherein the non-downlink sub-band is an uplink sub-band and/or a guard sub-band.

39. The method according to clause 38, wherein the non-downlink sub-band is an uplink sub-band.

40. The method according to any of clauses 36-39, further comprising: transmitting, to the communications device, an indication of the one or more modifications to the first set of resources.

41 . The method according to any of clauses 26-40, wherein the one or more modifications to the first set of resources include reducing an aggregation level of the one or more PDCCH candidates, wherein the aggregation level is a number of control channel elements (CCEs) in a PDCCH candidate.

42. The method according to clause 41 , wherein reducing the aggregation level comprises reducing the aggregation level to a nearest aggregation level included in a set of predefined aggregation levels.

43. The method according to any of clauses 41 or 42, wherein reducing the aggregation level comprises dropping the one or more PDCCH candidates based on a number of invalid REGs or CCEs in the PDCCH candidate exceeding a predetermined threshold.

44. The method according to clause 43, wherein the predetermined threshold is half an original aggregation level of the one or more PDCCH candidates.

45. The method according to clause 43, wherein the predetermined threshold is a minimum aggregation level in a set of predefined aggregation levels.

46. The method according to clause 43 or 45, wherein the predetermined threshold is 1 CCE.

47. The method according to any of clauses 41-42, wherein the one or more modifications to the first set of resources include dropping one of two or more duplicate PDCCH candidates, the duplicate PDCCH candidates being formed by the reduction of the aggregation level.

48. The method according to clause 47, where the duplicate PDCCH candidates have the same aggregation level and use the same CCEs.

49. The method according to any of clauses 41-48, wherein the one or more modifications to the first set of resources include relocating the one or more invalid REGs of the one or more PDCCH candidates in the time and/or frequency domains.

50. The method according to clause 49, wherein relocating the one or more invalid REGs comprises relocating the one or more invalid REGs in a time domain.

51 . The method according to clause 50, wherein relocating the one or more invalid REGs in a time domain comprises removing one or more REGs from the PDCCH candidate and repeating the one or more removed REGs in the time domain.

52. The method according to clause 50, wherein relocating the one or more invalid REGs in the time domain comprises repeating the one or more invalid REGs in the time domain. 53. The method according to clause 52, wherein repeating the one or more invalid REGs in the time domain comprises repeating one or more invalid CCEs, including the one or more REGs, in the time domain.

54. The method according to clause 53, wherein repeating the one or more invalid CCEs in the time domain comprises repeating the one or more PDCCH candidates in the time domain.

55. The method of any of clauses 52-54, further comprising transmitting, to the communications device, signalling indicating a number of repetitions for the one or more repeated REGs.

56. The method according to any of clauses 50-55, further comprising receiving signalling indicating time resources in which the relocated REGs are to be located.

57. The method according any of clauses 49-56, wherein the one or more modifications to the first set of resources include relocating the REGs in a frequency domain.

58. The method according to clause 57, wherein frequency resources to which the one or more invalid REGs are to be relocated are either included signalling transmitted by the infrastructure equipment or predefined.

59. The method according to any of clause 57 or 58, wherein a frequency offset for the one or more REGs is either indicated in signalling received by the communications device or predefined.

60. The method according to any of clauses 57-59, wherein relocating the REGs in the frequency domain comprises reconfiguring a CORESET for the PDCCH search space.

61 . The method according to any of clauses 49-60, wherein relocating the one or more invalid REGs comprises relocating one or more invalid CCEs, wherein the one or more invalid CCEs each comprise one or more invalid REGs.

62. The method according to clause 61 , wherein the one or more modifications to the first set of resources include relocating a set of multiple CCEs, the set of CCEs including one or more invalid CCEs.

63. The method according to clause 62, wherein a CORESET for the PDCCH search space includes a plurality of non-overlapping sets of CCEs.

64. The method according to any of clauses 62 or 63, wherein a number of sets of CCEs in the CORESET is based on a number of invalid CCEs.

65. The method according to any of clauses 63-64, wherein the CORESET includes a first set of CCEs and a second set of CCEs, wherein the first set of CCEs are relocated in the time domain and relocated in the frequency domain to the same frequency resources as the second set of CCEs.

66. The method according to any of clauses 41-65, wherein the CORESET for the PDCCH search space is an interleaved CORESET including interleaved CCEs, and wherein the one or more modifications to the first set of resources include changing the interleaved CORESET to a non-interleaved CORESET.

67. The method according to any of clauses 41-66, wherein the one or more PDCCH candidates are modified based on whether any uplink transmissions are scheduled to occur within a fixed time period of the PDCCH search space. 68. The method according to clause 67, wherein the fixed time period is a timing advance offset applied by the communications device for uplink transmissions.

69. The method according to clause 67, wherein the fixed time period is either indicated in signalling received by the communications device or predefined.

70. An infrastructure equipment comprising: a transceiver configured to transmit signals to and/or receive signals from a plurality of communications devices, and a controller configured in combination with the transceiver to: transmit, to the communications device, an indication of one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space, the one or more PDCCH candidates indicating a first set of resources for the communications device to monitor for a PDCCH transmission; and based on detecting a collision between the one or more PDCCH candidates and a nondownlink sub-band of a timing slot, transmit, for receipt by the communications device, a PDCCH using a second set of resources different to the first set of resources, the second set of resources having one or more modifications relative to the first set of resources, and wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device.

71 . Circuitry for an infrastructure equipment comprising: transceiver circuitry configured to transmit signals to and/or receive signals from a plurality of communications devices, and controller circuitry configured in combination with the transceiver to: transmit, to the communications device, an indication of one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space, the one or more PDCCH candidates indicating a first set of resources for the communications device to monitor for a PDCCH transmission; and based on detecting a collision between the one or more PDCCH candidates and a nondownlink sub-band of a timing slot, transmit, for receipt by the communications device, a PDCCH using a second set of resources different to the first set of resources, the second set of resources having one or more modifications relative to the first set of resources, and wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device.

REFERENCES

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

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

[3] TS38.211 , “Physical channels and modulation (Release 17),” v17.3.0

Claims

1. A method of operating a communications device configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network via a wireless radio interface provided by the wireless communications network, the method comprising: detecting a collision between one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space and a non-downlink sub-band of a timing slot, wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device; based on detecting the collision between the one or more PDCCH candidates and the non-downlink sub-band, modifying the one or more PDCCH candidates that collide with the non-downlink sub-band to overcome the collision between the one or more PDCCH candidates and the non-downlink sub-band.

2. The method according to claim 1 , wherein the PDCCH search space includes a control resource set (CORESET) comprising a set of REGs for monitoring for PDCCH transmissions, and wherein the one or more PDCCH candidates are each a set of one or more control channel elements (CCEs) which the communications device is configured to monitor for PDCCH transmissions, wherein the one or more CCEs each comprise a plurality of REGs of the set of REGs included in the CORESET.

3. The method according to claim 1 , wherein the non-downlink sub-band is an uplink subband and/or a guard sub-band.

4. The method according to claim 3, wherein the non-downlink sub-band is an uplink subband.

5. The method according to claim 1 , wherein modifying the one or more PDCCH candidates includes reducing an aggregation level of the one or more PDCCH candidates, wherein the aggregation level is a number of control channel elements (CCEs) in a PDCCH candidate.

6. The method according to claim 5, wherein reducing the aggregation level comprises reducing the aggregation level to a nearest aggregation level included in a set of predefined aggregation levels.

7. The method according to claim 5, wherein reducing the aggregation level comprises dropping the one or more PDCCH candidates based on a number of invalid REGs or CCEs in the PDCCH candidate exceeding a predetermined threshold.

8. The method according to claim 7, wherein the predetermined threshold is half an original aggregation level of the one or more PDCCH candidates.

9. The method according to claim 7, wherein the predetermined threshold is a minimum aggregation level in a set of predefined aggregation levels.

10. The method according to claim 7, wherein the predetermined threshold is 1 CCE.

11. The method according to claim 4, wherein modifying the one or more PDCCH candidates further comprises dropping one of two or more duplicate PDCCH candidates, the duplicate PDCCH candidates being formed by the reduction of the aggregation level.

12. The method according to claim 11 , where the duplicate PDCCH candidates have the same aggregation level and use the same CCEs.

13. The method according to claim 1 , wherein modifying the one or more PDCCH candidates includes relocating the one or more invalid REGs of the one or more PDCCH candidates in the time and/or frequency domains.

14. The method according to claim 13, wherein relocating the one or more invalid REGs comprises relocating the one or more invalid REGs in a time domain.

15. The method according to claim 14, wherein relocating the one or more invalid REGs in a time domain comprises removing one or more REGs from the PDCCH candidate and repeating the one or more removed REGs in the time domain.

16. The method according to claim 14, wherein relocating the one or more invalid REGs in the time domain comprises repeating the one or more invalid REGs in the time domain.

17. The method according to claim 16, wherein repeating the one or more invalid REGs in the time domain comprises repeating one or more invalid CCEs, including the one or more REGs, in the time domain.

18. The method according to claim 17, wherein repeating the one or more invalid CCEs in the time domain comprises repeating the one or more PDCCH candidates in the time domain.

19. The method of claim 16, further comprising receiving signalling indicating a number of repetitions for the one or more repeated REGs.

20. The method according to claim 14, further comprising receiving signalling indicating time resources in which the relocated REGs are to be located.

21. The method according to claim 13, wherein modifying the one or more PDCCH candidates includes relocating the REGs in a frequency domain.

22. The method according to claim 21 , wherein frequency resources to which the one or more invalid REGs are to be relocated are either indicated in signalling received by the communications device or predefined.

23. The method according to claim 21 , wherein a frequency offset for the one or more REGs is either indicated in signalling received by the communications device or predefined.

24. The method according to claim 21 , wherein relocating the REGs in the frequency domain comprises reconfiguring a CORESET for the PDCCH search space.

25. The method according to claim 13, wherein relocating the one or more invalid REGs comprises relocating one or more invalid CCEs, wherein the one or more invalid CCEs each comprise one or more invalid REGs.

26. The method according to claim 25, wherein modifying the one or more PDCCH candidates comprises relocating a set of multiple CCEs, the set of CCEs including one or more invalid CCEs.

27. The method according to claim 26, wherein a CORESET for the PDCCH search space includes a plurality of non-overlapping sets of CCEs.

28. The method according to claim 26, wherein a number of sets of CCEs in the CORESET is based on a number of invalid CCEs.

29. The method according to claim 27, wherein the CORESET includes a first set of CCEs and a second set of CCEs, wherein the first set of CCEs are relocated in the time domain and relocated in the frequency domain to the same frequency resources as the second set of CCEs.

30. The method according to claim 1 , wherein the CORESET for the PDCCH search space is an interleaved CORESET including interleaved CCEs, and wherein modifying the one or more PDCCH candidates comprises changing the interleaved CORESET to a non-interleaved CORESET.

31 . The method according to claim 1 , wherein the one or more PDCCH candidates are modified based on whether any uplink transmissions are scheduled to occur within a fixed time period of the PDCCH search space.

32. The method according to claim 31 , wherein the fixed time period is a timing advance offset applied by the communications device for uplink transmissions.

33. The method according to claim 31 , wherein the fixed time period is either indicated in signalling received by the communications device or predefined.

34. A communications device, the communications device comprising: a transceiver configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network and/or one or more other communications devices, and a controller configured in combination with the transceiver to: detect a collision between one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space and a non-downlink sub-band of a timing slot, wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device; based on detecting the collision between the one or more PDCCH candidates and the non-downlink sub-band, modify the one or more PDCCH candidates that collide with the non-downlink sub-band to overcome the collision between the one or more PDCCH candidates and the non-downlink sub-band.

35. Circuitry for a communications device comprising: transceiver circuitry configured to transmit signals to and/or to receive signals from an infrastructure equipment of a wireless communications network and/or one or more other communications devices, and controller circuitry configured in combination with the transceiver to: detect a collision between one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space and a non-downlink sub-band of a timing slot, wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device; based on detecting the collision between the one or more PDCCH candidates and the non-downlink sub-band, modify the one or more PDCCH candidates that collide with the non-downlink sub-band to overcome the collision between the one or more PDCCH candidates and the non-downlink sub-band.

36. A method for an infrastructure equipment configured to transmit signals to and/or to receive signals from a communications device of a wireless communications network via a wireless radio interface provided by the wireless communications network, the method comprising: transmitting, to the communications device, an indication of one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space, the one or more PDCCH candidates indicating a first set of resources for the communications device to monitor for a PDCCH transmission; and based on detecting a collision between the one or more PDCCH candidates and a nondownlink sub-band of a timing slot, transmitting, for receipt by the communications device, a PDCCH using a second set of resources different to the first set of resources, the second set of resources having one or more modifications relative to the first set of resources, and wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device.

37. The method according to claim 36, wherein the first set of resources is indicated by a control resource set (CORESET) comprising a set of REGs for monitoring for PDCCH transmissions, and wherein the one or more PDCCH candidates are each a set of one or more control channel elements (CCEs) for monitoring by the communications device for PDCCH transmissions, wherein the one or more CCEs each comprise a plurality of REGs of the set of REGs included in the CORESET.

38. The method according to claim 36, wherein the non-downlink sub-band is an uplink sub-band and/or a guard sub-band.

39. The method according to claim 38, wherein the non-downlink sub-band is an uplink sub-band.

40. The method according to claim 36, further comprising: transmitting, to the communications device, an indication of the one or more modifications to the first set of resources.

41. The method according to claim 36, wherein the one or more modifications to the first set of resources include reducing an aggregation level of the one or more PDCCH candidates, wherein the aggregation level is a number of control channel elements (CCEs) in a PDCCH candidate.

42. The method according to claim 41 , wherein reducing the aggregation level comprises reducing the aggregation level to a nearest aggregation level included in a set of predefined aggregation levels.

43. The method according to claim 41 , wherein reducing the aggregation level comprises dropping the one or more PDCCH candidates based on a number of invalid REGs or CCEs in the PDCCH candidate exceeding a predetermined threshold.

44. The method according to claim 43, wherein the predetermined threshold is half an original aggregation level of the one or more PDCCH candidates.

45. The method according to claim 43, wherein the predetermined threshold is a minimum aggregation level in a set of predefined aggregation levels.

46. The method according to claim 43, wherein the predetermined threshold is 1 CCE.

47. The method according to claim 41 , wherein the one or more modifications to the first set of resources include dropping one of two or more duplicate PDCCH candidates, the duplicate PDCCH candidates being formed by the reduction of the aggregation level.

48. The method according to claim 47, where the duplicate PDCCH candidates have the same aggregation level and use the same CCEs.

49. The method according to claim 41 , wherein the one or more modifications to the first set of resources include relocating the one or more invalid REGs of the one or more PDCCH candidates in the time and/or frequency domains.

50. The method according to claim 49, wherein relocating the one or more invalid REGs comprises relocating the one or more invalid REGs in a time domain.

51. The method according to claim 50, wherein relocating the one or more invalid REGs in a time domain comprises removing one or more REGs from the PDCCH candidate and repeating the one or more removed REGs in the time domain.

52. The method according to claim 50, wherein relocating the one or more invalid REGs in the time domain comprises repeating the one or more invalid REGs in the time domain.

53. The method according to claim 52, wherein repeating the one or more invalid REGs in the time domain comprises repeating one or more invalid CCEs, including the one or more REGs, in the time domain.

54. The method according to claim 53, wherein repeating the one or more invalid CCEs in the time domain comprises repeating the one or more PDCCH candidates in the time domain.

55. The method of claim 52, further comprising transmitting, to the communications device, signalling indicating a number of repetitions for the one or more repeated REGs.

56. The method according to claim 50, further comprising receiving signalling indicating time resources in which the relocated REGs are to be located.

57. The method according claim 49, wherein the one or more modifications to the first set of resources include relocating the REGs in a frequency domain.

58. The method according to claim 57, wherein frequency resources to which the one or more invalid REGs are to be relocated are either included signalling transmitted by the infrastructure equipment or predefined.

59. The method according to claim 57, wherein a frequency offset for the one or more REGs is either indicated in signalling received by the communications device or predefined.

60. The method according to claim 57, wherein relocating the REGs in the frequency domain comprises reconfiguring a CORESET for the PDCCH search space.

61. The method according to claim 49, wherein relocating the one or more invalid REGs comprises relocating one or more invalid CCEs, wherein the one or more invalid CCEs each comprise one or more invalid REGs.

62. The method according to claim 61 , wherein the one or more modifications to the first set of resources include relocating a set of multiple CCEs, the set of CCEs including one or more invalid CCEs.

63. The method according to claim 62, wherein a CORESET for the PDCCH search space includes a plurality of non-overlapping sets of CCEs.

64. The method according to claim 62, wherein a number of sets of CCEs in the CORESET is based on a number of invalid CCEs.

65. The method according to claim 63, wherein the CORESET includes a first set of CCEs and a second set of CCEs, wherein the first set of CCEs are relocated in the time domain and relocated in the frequency domain to the same frequency resources as the second set of CCEs.

66. The method according to claim 41 , wherein the CORESET for the PDCCH search space is an interleaved CORESET including interleaved CCEs, and wherein the one or more modifications to the first set of resources include changing the interleaved CORESET to a non-interleaved CORESET.

67. The method according to claim 41 , wherein the one or more PDCCH candidates are modified based on whether any uplink transmissions are scheduled to occur within a fixed time period of the PDCCH search space.

68. The method according to claim 67, wherein the fixed time period is a timing advance offset applied by the communications device for uplink transmissions.

69. The method according to claim 67, wherein the fixed time period is either indicated in signalling received by the communications device or predefined.

70. An infrastructure equipment comprising: a transceiver configured to transmit signals to and/or receive signals from a plurality of communications devices, and a controller configured in combination with the transceiver to: transmit, to the communications device, an indication of one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space, the one or more PDCCH candidates indicating a first set of resources for the communications device to monitor for a PDCCH transmission; and based on detecting a collision between the one or more PDCCH candidates and a non-downlink sub-band of a timing slot, transmit, for receipt by the communications device, a PDCCH using a second set of resources different to the first set of resources, the second set of resources having one or more modifications relative to the first set of resources, and wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device.

71 . Circuitry for an infrastructure equipment comprising: transceiver circuitry configured to transmit signals to and/or receive signals from a plurality of communications devices, and controller circuitry configured in combination with the transceiver to: transmit, to the communications device, an indication of one or more physical downlink control channel (PDCCH) candidates of a PDCCH search space, the one or more PDCCH candidates indicating a first set of resources for the communications device to monitor for a PDCCH transmission; and based on detecting a collision between the one or more PDCCH candidates and a non-downlink sub-band of a timing slot, transmit, for receipt by the communications device, a PDCCH using a second set of resources different to the first set of resources, the second set of resources having one or more modifications relative to the first set of resources, and wherein detecting the collision comprises determining that the one or more PDCCH candidates include one or more invalid resource element groups (REGs), the one or more invalid REGs overlapping a non-downlink sub-band for the communications device.