GB2578631A

GB2578631A - Resource scheduling for unlicensed band operation

Info

Publication number: GB2578631A
Application number: GB1817917.6A
Authority: GB
Inventors: Salim Umer; Jechoux Bruno
Original assignee: TCL Communication Ltd
Current assignee: TCL Communication Ltd
Priority date: 2018-11-02
Filing date: 2018-11-02
Publication date: 2020-05-20
Anticipated expiration: 2038-11-02
Also published as: GB2578631B; GB201817917D0; CN112602363A; WO2020088419A1; CN112602363B

Abstract

Dynamic allocation of paging and/or RACH resources in a cellular wireless communication system operating on an unlicensed medium is disclosed. Due to the uncertainty of operating within an unlicensed medium, there may be uplink and downlink delays between a base station and a user equipment (UE). A base station operating in an unlicensed medium acquires access to a transmission medium using a listen-before-talk process. Resources are allocated for Paging Occasions (POs) and/or RACH transmissions during the period of access acquired by the base station. A message is transmitted from the base station to UEs connected to the base station indicating these resource allocations. The UE is then able to utilise the resources to receive paging messages or make RACH transmission. The position of resources is modified to improve the probability of resources being available during the period for which transmission channel access has been obtained. The message may be broadcast, sent in a common DCI message within a common Control Resource Set (COREST).

Description

Resource Scheduling for Unlicensed Band Operation

Technical Field

[1] The following disclosure relates to wireless communication systems operating in unlicensed bands. In particular, the following disclosure relates to allocation of resources for paging and random access messages.

Background

[2] Wireless communication systems, such as the third-generation (3G) of mobile telephone standards and technology are well known. Such 3G standards and technology have been developed by the Third Generation Partnership Project (3GPP). The 3rd generation of wireless communications has generally been developed to support macro-cell mobile phone communications. Communication systems and networks have developed towards a broadband and mobile system.

[3] In cellular wireless communication systems User Equipment (UE) is connected by a wireless link to a Radio Access Network (RAN). The RAN comprises a set of base stations which provide wireless links to the UEs located in cells covered by the base station, and an interface to a Core Network (CN) which provides overall network control. As will be appreciated the RAN and CN each conduct respective functions in relation to the overall network. For convenience the term cellular network will be used to refer to the combined RAN & CN, and it will be understood that the term is used to refer to the respective system for performing the disclosed function.

[4] The 3rd Generation Partnership Project has developed the so-called Long Term Evolution (LTE) system, namely, an Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN), for a mobile access network where one or more macro-cells are supported by a base station known as an eNodeB or eNB (evolved NodeB). More recently, LTE is evolving further towards the so-called 5G or new radio (NR) systems where one or more cells are supported by a base station known as a next generation NodeB (gNB). NR is proposed to utilise an Orthogonal Frequency Division Multiplexed (OFDM) physical transmission format.

[5] The use of unlicensed spectrum presents particular challenges to a cellular system, particularly in relation to fairly sharing access to the transmission medium, and the timing of transmissions. Listen-before-talk (LBT) is adopted as the fundamental coexistence mechanism for unlicensed spectrum, whereby a radio transmitter is required to apply a clear channel assessment (CCA) check prior to transmission. CCA involves at least energy detection (ED) over a time duration with a certain threshold (ED threshold) to determine if a channel is occupied or is clear. If the channel is occupied, random back-off within a contention window applies, so that there is a minimum time duration where the channel is clear before the transmitter can transmit. In order to protect Wi-Fi ACK transmissions, a defer period (e.g. 43ps for best effort traffic) is applied after each busy CCA slot before resuming back-off. After the transmitter has gained access to the channel, the transmitter is only allowed to transmit for a limited duration referred to as the maximum channel occupancy time (MCOT).

[6] A transmitter within a set of devices may obtain access to the transmission medium for all devices of the set. For example, a base station may gain access to the transmission medium for all UEs related to that base station. Subject to a suitable CCA, each UE may then transmit within the MCOT obtained by the base station.

[7] In order to reduce power consumption and share resources, UEs are configured to only listen for messages in certain windows, and to only transmit in certain windows. For example, when in idle mode UEs may sleep and only wake at intermittent Paging Occasions (POs) to listen for paging messages indicating the need to wake for a downlink transmission. Similarly, when a UE wishes to make an uplink transmission the UE sends an uplink request to the base station. This request is sent on the Random Access Channel (RACH). That RACH transmission can only be made at certain intervals.

[8] Due to the limited duration of the MCOT and the uncertainty of the unlicensed medium access it is possible that no POs or RACH windows fall within the period or fall very late in the period. This may limit the ability of a UE to communicate with the base station. For example, if a UE has an uplink message but the MCOT start time and the duration are such that it does not cover a RACH window, the UEs will not be able to initiate a request to the base station. They need to wait for the next occasion when the base station (or potentially a mobile within the same cell) wins the access rights over the unlicensed medium to be able to initiate RACH request on the configured resources. Thus there will be a delay until access to the transmission medium is secured and a subsequent RACH window falls within an MCOT. There may thus be significant latency in uplink transmissions, and the same applies for downlink due to delays in POs occurring in a period with transmission medium access.

[9] There is therefore a requirement for an improved method of resource allocation for unlicensed transmissions.

Summary

[10] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[11] There is provided a method for dynamic allocation of paging and/or RACH resources in a cellular wireless communication system operating on an unlicensed medium, the method comprising the steps of at a base station acquiring access to a transmission medium utilising a listen-before-talk process; allocating resources for Paging Occasions (POs) and/or RACH transmissions during the period of access acquired by the base station; and transmitting a message from the base station to UEs connected to the base station indicating these resource allocations.

[12] The message may be a broadcast message.

[13] The message may be sent to all UEs connected to the base station.

[14] The message may be a group-common message.

[15] The indication may be sent in a common DCI message.

[16] The common DCI message may be transmitted in a common COntrol REsource SET (CORESET).

[17] The common DCI message may be transmitted at the start of the period for which access has been acquired.

[18] At least one UE may be configured to listen for a common DCI message on specific resources with a defined periodicity.

[19] At least one UE may be configured to listen for a common DCI message at at least one time interval relative to its PO and/or RACH occasion.

[20] At least one UE may be configured to listen for a common DCI message in defined subframes of the frame in which its PO and/or RACH occasion is positioned.

[21] The indication message may be a Synchronization Sequence Block (SSB) in which the indication of resources is encoded, together with synchronisation signals.

[22] There is also provided a method for dynamic allocation of paging and/or RACH resources in a cellular wireless communication system operating on an unlicensed medium, the method comprising the steps of at a UE receiving a message from the base station which the UE is connected indicating resources allocated for Paging Occasions (POs) and/or RACH transmissions during a period of access acquired by the base station, and at the UE utilising the indicated resources to receive paging messages or make RACH transmissions.

[23] The message may be a broadcast message.

[24] The message may be sent to all UEs connected to the base station.

[25] The message may be a group-common message.

[26] The message may be a common DCI message.

[27] The common DCI message may be received in a common COntrol REsource SET (CORESET).

[28] The common DCI message may be received at the start of the period for which access has been acquired.

[29] The UE may be configured to listen for the common DCI message on specific resources with a defined periodicity.

[30] The UE is configured to listen for a common DCI message at at least one time interval relative to its PO and/or RACH occasion.

[31] The UE may be configured to listen for a common DCI message in defined subframes of the frame in which its PO and/or RACH occasion is positioned.

[32] The message may be a Synchronization Sequence Block (SSB) in which the indication of resources is encoded.

[33] There is also provided a base station configured to perform the method described above.

[34] There is also provided a UE configured to perform the method described above.

Brief description of the drawings

[35] Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Like reference numerals have been included in the respective drawings to ease understanding.

[36] Figure 1 shows a schematic diagram of an example cellular wireless communications network.

[37] Detailed description of the preferred embodiments [38] Those skilled in the art will recognise and appreciate that the specifics of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative settings.

[39] Figure 1 shows a schematic diagram of three base stations (for example, eNB or gNBs depending on the particular cellular standard and terminology) forming a cellular network. Typically, each of the base stations will be deployed by one cellular network operator to provide geographic coverage for UEs in the area. The base stations form a Radio Area Network (RAN). Each base station provides wireless coverage for UEs in its area or cell. The base stations are interconnected via the X2 interface and are connected to the core network via the S1 interface. As will be appreciated only basic details are shown for the purposes of exemplifying the key features of a cellular network.

[40] The base stations each comprise hardware and software to implement the RAN's functionality, including communications with the core network and other base stations, carriage of control and data signals between the core network and UEs, and maintaining wireless communications with UEs associated with each base station. The core network comprises hardware and software to implement the network functionality, such as overall network management and control, and routing of calls and data.

[41] When a base station is communicating with the devices (for example mobile users or other devices) using the unlicensed medium, it has to win the right to transmit on the unlicensed medium. Regulations allow both the base station and the mobiles to perform CCA to gain channel access though typically base stations will perform the CCA and the users will do only when configured by their base station. The time at which a base station obtains access to a transmission medium (either for itself to transmit, or for a related UE to transmit) is random in relation to system timings. This happens as many different networks and devices may share the unlicensed resources with their different timings and utilisation intervals. Periodic resources cannot therefore provide a reliable transmission opportunity within the MCOT after access is obtained. The conventional periodic POs and RACH windows cannot therefore be relied upon. It is even possible that if MOOT is less than the PO/RACH period, no transmission opportunities will occur leading to an inability for the network and UE to communicate. For convenience the period during which a base station & its UEs have access to the transmission medium will be referred to as a Transmission Opportunity (TxOP) [42] The following disclosure provides methods and processes to ensure transmission opportunities occur while channel access is available. PO and RACH windows are dynamically configured depending on the system status and/or channel access acquisition.

[43] In an example, multiple RACH configurations may be defined and the network may instruct a UE to select a particular configuration for use during a TxOP. For example, a first configuration may provide a RACH occasion in certain time-frequency resource in every 3rd sub-frame. The second configuration may be such that a RACH occasion appears every 3rd, 6th and 9th sub-frame in certain time-frequency resources. The base station may then transmit an indication of which configuration to use. This configuration may be semi-static or may apply only for a current (or set of) TxOP. In this simple example a 1 bit signal to a user or group may indicate whether configuration 1 or configuration 2 is active in the current TxOP. The same principle applies to POs.

[44] In an example, a default configuration for PO and RACH resources may be active unless indicated otherwise. This configuration may be overwritten by, or changed to, a different configuration if the base station considers that necessary. Such a process may reduce control signalling as a message is only required when a change of configuration from the default configuration is needed. It is typical for a base station to obtain access to the transmission medium on behalf of all related UEs, and hence the base station is aware when a problem with windows falling outside a TxOP may occur. The base station can thus control PO and RACH resources appropriately.

[45] Current system status may be utilised to select an appropriate configuration. For example, if there are a large number of idle mode UEs in a cell and few active users, the base station may increase resources available for POs to maximise the ability of the base station to page idle mode UEs. Similarly, if there are a large number of active UEs making frequent uplink transmissions, RACH resources may be increased to increase the probability of a UE being able to make a RACH transmission in a TxOP.

[46] Common, or group-common, signalling may be utilised to transmit resource configurations to UEs to control the signalling overhead of re-configuring resources.

[47] A set of RACH configurations and a set of PO configurations may be defined. Combinations of those configurations may each be assigned a reference such that a base station can indicate to a UE the configuration to utilise by transmitting that reference. This may reduce the control overhead. In an example of two RACH configurations and two PO configurations, all combinations can be indicated by a 2-bit field. Similarly, a separate reference could be utilised to indicate each of RACH and PO configurations.

[48] The configuration indication may be transmitted in a common DCI message which may reduce signalling overhead. The common DCI may be transmitted at the start of a TxOP in a common COntrol REsource SET (CORESET) such that each UE receives PO and RACH resource indications early in each TxOP.

[49] If a carrier in unlicensed spectrum is used as a TDD carrier, which is actually the typical duplexing mode for the unlicensed spectrum, the base station may need to indicate the UL-DL split using a Slot Indication Format (SFI) field of the DCI. Other information may also be included in the common DCI such as control information regarding resources or durations of TxOP, thus making efficient utilisation of the Tx0P.

[50] In order to receive the common DCI the idle UEs need to monitor the relevant common CORESETs when it may be transmitted as per the configurations sent by the base station. This may increase power consumption of idle mode UEs compared to operating using licensed carriers as then idle mode UEs will not listen to any such DCI but only paging indication at paging occasions. An additional issue in the unlicensed medium is the uncertainty that the UEs may not know a-priori when their base station will gain access to the medium. Thus a UE may frequently wake-up to listen to common DCI but without such a common DCI being transmitted if the base station does not have access. To avoid monitoring the DCI on every such occasion, a UE may be configured to listen for a common DCI (carrying the paging/RACH resource indication) on specific resources with a certain periodicity. In one example a UE may be configured to listen to common DCI only once on a specific time in relation to its PO. For example, if the UE is configured for paging in the 3rd subframe of every 2nd frame, it may listen for a common DCI in the 5th and 8th subframe of the frame where it has its PO. Different configurations may be selected so as to cover the network and UE's requirements to communicate with each other.

[51] In another setting, the UEs may be configured to listen to common DCI after their PO or RACH resource with a specific timing. This setting can be very suitable for RACH in particular. Before RACH transmission, normally UEs perform a CCA, if they find the medium busy, it may indicate that the unlicensed medium is being used by another group of devices currently. Thus they may be configured to listen to common DCI after this unavailable RACH occasion where the base station may send the newly allocated RACH resources.

[52] The positions of paging and RACH resources, if configured in a semi-static or dynamic manner, can be either fixed with respect to the LBT success timing or can be selected from a predefined set of configurations. For example, a reference for a certain set of values may be transmitted which is used at the UE to retrieve the require configuration from the pre-defined options.

[53] The common DCI carrying the indication of PO/RACH may be sent at the beginning of a transmission burst (start of COT or TxOP) on the unlicensed carrier after the base station gains access to the transmission medium. An advantage of transmitting the indication at the start of a TxOP from detection perspective is that if there are SSB, preamble or other signals at the start of the burst, the UE will decode the common DCI in about the same time and also have better channel estimates due to the other signals. Another advantage of using a common DCI at the start of the burst is that the resource information is available at the start of the TxOP and hence before the actual resources occur. This gives ample time to the UEs to listen to paging or transmit RACH on the newly allocated resources.

[54] In a further example, PO and RACH resources may be indicated in a Synchronization Sequence Block (SSB), which are an integral part of the Discovery Reference Signal (DRS) for an unlicensed carrier. SSBs will be transmitted at the beginning of a TxOP. SSBs provide time-frequency synchronization through PSS, SSS and for master information block (MIB) transmission in PBCH, which overall provides the cell identity (Cell ID), complete timing information and the necessary control information to be able to find the remaining minimum system information (RMSI). Due to the very precise structure of the SSB, and the importance for (initial) synchronization, it is preferable not to modify the payload of the SSB. However, a limited amount of information may be indicated by modulating or modifying an information field indirectly. For example, the DMRS sequence initialization for PBCH could be modified. Currently the DMRS sequence initialization conveys the partial information of SSB index for 8 to 64 beams, and conveys the SSB index plus the half frame indication for 4 beam setting.

[55] Connected mode Ues will normally listen to both SSB and the common DCI so either example described above can be utilised to provide PO/RACH information. However, idle-mode UEs may be asleep and not listening to each SSB. Also, asleep idle-mode UEs are not supposed to decode the DCI. Requiring idle-mode UEs to listen for SSB or common DCI may thus reduce the UEs sleep time and increase power consumption. However, idle-mode UEs do listen to SSB (or DRS) near their PO wake-up time to obtain updated synchronization and channel estimation. In the case of unlicensed transmission resources, prior to their wake-up time, UEs also try to establish if the base station has access to unlicensed transmission medium. Providing PO/RACH indications in SSB can also be expected to work for idle-mode UEs.

[56] To reduce power consumption of idle-mode UEs, the UEs may be configured to only listen to a common DCI indicating PO/RACH resources. Idle-mode UEs may be configured to decode the common DCI in close proximity to their configured wake-up time, preferable slightly in advance. If the common DCI is sent only in the start of the TxOP, then idle-mode UEs have to be configured to wake up and decode this common DCI only in the occasions where they have to wake-up as per their configured DRx period.

[57] In order to reduce the burden of decoding a common DCI carrying PO/RACH resource information the common DCI may be repeated multiple times in the TxOP. This increases the probability of the common DCI arriving in the UEs normal listening duration. The repeated transmission may also improve reliability for UEs (both idle and connected) which receive more than one transmission of the message. The repeated transmission also ensures UEs which may have missed the start of the [58] One method to reduce the burden of decoding the common DCI in the start of the COT for idle mode users can be to transmit the common DCI carrying the updated paging and RACH resources multiple times in the COT. This will enable the decoding of the common DCI by idle mode users with little increase of their wake-up duration. The repeated transmission of common DCI can have the reliability advantage for all connected and idle mode users. It is also possible that a UE misses the start of a TxOP and was not able to decode a common DCI transmitted at the start. The UE can, though, receive a repeated transmission and thus can receive the PO/RACH configuration information.

[59] For the unlicensed systems which use preambles at the start of their TxOP, a different method can be selected to dynamically indicate the paging/RACH resources. In this method, the paging/RACH resources, which are pre-configured by the base station, are shifted in time with respect to start of the TxOP. The shift can be equal to the difference of the time between some reference system time and the start of the TxOP. In one example, the shift can be the time between the sub-frame 0 of system time and the start of the first sub-frame in the TxOP. Thus all the paging and RACH resources will be shifted in this TxOP equal to this shift which is the misalignment of the TxOP with respect to the system timings. This method may be interesting as it allows the dynamic provisioning and management of paging and RACH resources without any dynamic signalling. This method works as the UEs are supposed to listen to preamble which provides them the indication about the start of the TxOP. This method can be employed without preambles when the base station is using some other techniques to inform the users about the start of the TxOP, for example SSB signalling, DRS signalling or some other suitable signalling.

[60] The disclosure hereinbefore thus allows the definition of PO and RACH resources within a TxOP to improve the chances for communication during the TxOP. Such a system enables mitigation of difficulties due to the unpredictable start-time of TxOPs in systems using an LBT process to gain access to a transmission medium. The timing and/or resources for each of PO and RACH may be modified independently, or in conjunction.

[61] The signal processing functionality of the embodiments of the invention especially the gNB and the UE may be achieved using computing systems or architectures known to those who are skilled in the relevant art. Computing systems such as, a desktop, laptop or notebook computer, hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe, server, client, or any other type of special or general purpose computing device as may be desirable or appropriate for a given application or environment can be used. The computing system can include one or more processors which can be implemented using a general or special-purpose processing engine such as, for example, a microprocessor, microcontroller or other control module.

[62] The computing system can also include a main memory, such as random access memory (RAM) or other dynamic memory, for storing information and instructions to be executed by a processor. Such a main memory also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computing system may likewise include a read only memory (ROM) or other static storage device for storing static information and instructions for a processor.

[63] The computing system may also include an information storage system which may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a compact disc (CD) or digital video drive (DVD) read or write drive (R or RVV), or other removable or fixed media drive. Storage media may include, for example, a hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that is read by and written to by media drive. The storage media may include a computer-readable storage medium having particular computer software or data stored therein.

[64] In alternative embodiments, an information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. Such components may include, for example, a removable storage unit and an interface, such as a program cartridge and cartridge interface, a removable memory (for example, a flash memory or other removable memory module) and memory slot, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage unit to computing system.

[65] The computing system can also include a communications interface. Such a communications interface can be used to allow software and data to be transferred between a computing system and external devices. Examples of communications interfaces can include a modem, a network interface (such as an Ethernet or other NIC card), a communications port (such as for example, a universal serial bus (USB) port), a PCMCIA slot and card, etc. Software and data transferred via a communications interface are in the form of signals which can be electronic, electromagnetic, and optical or other signals capable of being received by a communications interface medium.

[66] In this document, the terms 'computer program product', 'computer-readable medium' and the like may be used generally to refer to tangible media such as, for example, a memory, storage device, or storage unit. These and other forms of computer-readable media may store one or more instructions for use by the processor comprising the computer system to cause the processor to perform specified operations. Such instructions, generally 45 referred to as computer program code' (which may be grouped in the form of computer programs or other groupings), when executed, enable the computing system to perform functions of embodiments of the present invention. Note that the code may directly cause a processor to perform specified operations, be compiled to do so, and/or be combined with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions) to do so.

[67] The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory. In an embodiment where the elements are implemented using software, the software may be stored in a computer-readable medium and loaded into computing system using, for example, removable storage drive. A control module (in this example, software instructions or executable computer program code), when executed by the processor in the computer system, causes a processor to perform the functions of the invention as described herein.

[68] Furthermore, the inventive concept can be applied to any circuit for performing signal processing functionality within a network element. It is further envisaged that, for example, a semiconductor manufacturer may employ the inventive concept in a design of a stand-alone device, such as a microcontroller of a digital signal processor (DSP), or application-specific integrated circuit (ASIC) and/or any other sub-system element.

[69] It will be appreciated that, for clarity purposes, the above description has described embodiments of the invention with reference to a single processing logic. However, the inventive concept may equally be implemented by way of a plurality of different functional units and processors to provide the signal processing functionality. Thus, references to specific functional units are only to be seen as references to suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organisation.

[70] Aspects of the invention may be implemented in any suitable form including hardware, software, firmware or any combination of these. The invention may optionally be implemented, at least partly, as computer software running on one or more data processors and/or digital signal processors or configurable module components such as FPGA devices.

[71] Thus, the elements and components of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term 'comprising' does not exclude the presence of other elements or steps.

[72] Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by, for example, a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also, the inclusion of a feature in one category of claims does not imply a limitation to this category, but rather indicates that the feature is equally applicable to other claim categories, as appropriate.

[73] Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. In addition, singular references do not exclude a plurality. Thus, references to 'a', 'an', 'first', second', etc. do not preclude a plurality.

[74] Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term 'comprising' or "including" does not exclude the presence of other elements.

Claims

Claims A method for dynamic allocation of paging and/or RACH resources in a cellular wireless communication system operating on an unlicensed medium, the method comprising the steps of at a base station acquiring access to a transmission medium utilising a listen-beforetalk process; allocating resources for Paging Occasions (POs) and/or RACH transmissions during the period of access acquired by the base station; and transmitting a message from the base station to UEs connected to the base station indicating these resource allocations.
2. A method according to claim 1, wherein the message is a broadcast message.
3. A method according to claim 2, wherein the message is sent to all UEs connected to the base station.
4. A method according to claim 1, wherein the message is a group-common message.
A method according to any preceding claim, wherein the indication is sent in a common DCI message.
6. A method according to claim 5, wherein the common DCI message is transmitted in a common COntrol REsource SET (CORESET).
7. A method according to claim 5 or claim 6 wherein the common DCI message is transmitted at the start of the period for which access has been acquired.
8. A method according to claim 5, wherein at least one UE is configured to listen for a common DCI message on specific resources with a defined periodicity.
9. A method according to claim 5, wherein at least one UE is configured to listen for a common DCI message at at least one time interval relative to its PO and/or RACH occasion.
10. A method according to claim 9, wherein the at least one UE is configured to listen for a common DCI in defined subframes of the frame in which its PO and/or RACH occasion is positioned.
11. A method according to claim 1, wherein the indication message is a Synchronization Sequence Block (SSB) in which the indication of resources is encoded, together with synchronisation signals.
12. A method for dynamic allocation of paging and/or RACH resources in a cellular wireless communication system operating on an unlicensed medium, the method comprising the steps of at a UE receiving a message from the base station which the UE is connected indicating resources allocated for Paging Occasions (POs) and/or RACH transmissions during a period of access acquired by the base station, and at the UE utilising the indicated resources to receive paging messages or make RACH transmissions.
13. A method according to claim 12, wherein the message is a broadcast message.
14. A method according to claim 13, wherein the message is sent to all UEs connected to the base station.
15. A method according to claim 12, wherein the message is a group-common message.
16 A method according to any of claims 12 to 15, wherein the message is a common DCI message.
17. A method according to claim 15, wherein the common DCI message is received in a common COntrol REsource SET (CORESET).
18. A method according to claim 16 or claim 17 wherein the common DCI message is received at the start of the period for which access has been acquired.
19. A method according to claim 16, wherein the UE is configured to listen for the common DCI message on specific resources with a defined periodicity.
20. A method according to claim 16, wherein the UE is configured to listen for a common DCI message at at least one time interval relative to its PO and/or RACH occasion.
21. A method according to claim 20, wherein the UE is configured to listen for a common DCI message in defined subframes of the frame in which its PO and/or RACH occasion is positioned.
22. A method according to claim 12, wherein the message is a Synchronization Sequence Block (SSB) in which the indication of resources is encoded.
23. A base station configured to perform the steps of any of claims 1 to 11.
24. A UE configured to perform the steps of any of claims 1 to 11.