Method, apparatus and computer program

Abstract

A user equipment (UE) provides, to a serving gNB, an indication of a warning of a potential radio link failure RLF or handover failure HOF to occur, and receives, from the serving gNB, a configuration

Description

Technical Field Various examples of this disclosure relate to methods, apparatuses, and computer programs for a communication network. Background A communication network can be seen as a facility that enables communications between two or more communication devices, or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network. A communication device may be provided with a service by an application server. Such communication networks operate in accordance with standards such as those provided by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of standards are the so-called 5G (5th Generation) standards provided by 3GPP. Summary Some examples of this disclosure will be described with respect to certain aspects. These aspects are not intended to indicate key or essential features of the embodiments of this disclosure, nor are they intended to be used to limit the scope thereof. Other features, aspects, and elements will be readily apparent to a person skilled in the art in view of this disclosure. For example, it should be appreciated that further aspects may be provided by the combination of any two or more of the various aspects described below. According to a first aspect, there is provided a communication device comprising: means for receiving, from a network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; and means for performing a reestablishment with the at least one neighbour cell according to the configuration. According to a second aspect, there is provided a method performed by a communication device, the method comprising: receiving, from a network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; and performing a re-establishment with the at least one neighbour cell according to the configuration. According to a third aspect, there is provided a communication device comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the communication device to perform: receiving, from a network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; and performing a re-establishment with the at least one neighbour cell according to the configuration. According to a fourth aspect, there is provided a computer program comprising instructions, which when executed by a communication device, cause the communication device to perform at least the following: receiving, from a network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; and performing a re-establishment with the at least one neighbour cell according to the configuration. According to a fifth aspect, there is provided a communication device comprising: circuitry configured to perform: receiving, from a network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; and circuitry configured to perform: performing a re-establishment with the at least one neighbour cell according to the configuration. The following are applicable to each (e.g., one or more, including all) of the above first to fifth aspects. In some examples, a cell that is serving the communication device is provided by the network entity. In some examples, the network entity is a source or serving network entity for the communication device. In some examples, the at least one neighbour cell is neighbouring a cell that is serving the communication device. In some examples, the configuration indicates at least one of the following: a pool of resources for contention-free random access, wherein the pool of resources is common for a plurality of neighbour cells; a pool of resources that comprises at least one contention-free random access preamble, wherein the pool of resources is common for a plurality of neighbour cells; resources for contention-free random access associated with each of a plurality of neighbour cells; or at least one contention-free random access preamble associated with each of a plurality of neighbour cells. In some examples, the communication device is caused to perform: selecting a neighbour cell from the plurality of neighbour cells, wherein the performing the re establishment comprises: performing the re-establishment with the neighbour cell that has been selected. In some examples, the communication device is caused to perform: providing, to the network entity, an indication of a warning of a potential radio link failure or handover failure to occur. In some examples, the configuration is received within one of the following: a radio resource control message, or a medium access control control element. In some examples, the re-establishment is performed based on a determination that a radio link failure or handover failure has occurred at the communication device. According to a sixth aspect, there is provided a network entity comprising: means for obtaining information related to the resources associated with at least one neighbour cell that are available for a re-establishment; and means for providing, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources associated with the at least one neighbour cell. According to a seventh aspect, there is provided a method performed by a network entity, the method comprising: obtaining information related to the resources associated with at least one neighbour cell that are available for a re-establishment; and providing, to a communication device, a configuration for contention-free random access for reestablishment, wherein the configuration indicates the resources associated with the at least one neighbour cell. According to an eight aspect, there is provided a network entity comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the network entity to perform: obtaining information related to the resources associated with at least one neighbour cell that are available for a re-establishment; and providing, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources associated with the at least one neighbour cell. According to a ninth aspect, there is provided a computer program comprising instructions, which when executed by a network entity, cause the network entity to perform at least the following: obtaining information related to the resources associated with at least one neighbour cell that are available for a re-establishment; and providing, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources associated with the at least one neighbour cell. According to a tenth aspect, there is provided a network entity comprising: circuitry configured to perform: obtaining information related to the resources associated with at least one neighbour cell that are available for a re-establishment; and circuitry configured to perform: providing, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources associated with the at least one neighbour cell. The following are applicable to each (e.g., one or more, including all) of the above sixth to tenth aspects. In some examples, the obtaining comprises one of: communicating with the at least one neighbour cell to determine the resources associated with the at least one neighbour cell that are available for a re-establishment; receiving, from the at least one neighbour cell, an indication of the resources associated with the at least one neighbour cell that are available for a re-establishment; or providing, to the at least one neighbour cell, a request for resources for contention-free random access for re-establishment; and receiving, from the at least one neighbour cell, an indication of resources for contention-free random access associated with the at least one neighbour cell that are available for a re-establishment. In some examples, the configuration indicates at least one of the following: a pool of resources for contention-free random access, wherein the pool of resources is common for a plurality of neighbour cells; a pool of resources that comprises at least one contention-free random access channel preamble, wherein the pool of resources is common for a plurality of neighbour cells; resources for contention-free random access associated with each of a plurality of neighbour cells; or at least one contention-free random access channel preamble associated with each of a plurality of neighbour cells. In some examples, the network entity is caused to perform: receiving, from the communication device, an indication of a warning of a potential radio link failure or handover failure to occur. In some examples, the configuration is provided to the communication device within one of the following: a radio resource control message, a medium access control control element. In some examples, the network entity is caused to perform: when a potential radio link failure or handover failure is to occur for the communication device, selecting a contention free random access preamble associated with the least one neighbour cell, wherein the selecting is based on the information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment; wherein the resources associated with the at least one neighbour cell indicated in the configuration comprises the contention free random access preamble associated with the least one neighbour cell that has been selected by the network entity. In some examples, the potential radio link failure or handover failure is determined by the network entity based on: an indication received from the communication device, wherein the indication is a warning of a potential radio link failure or handover failure to occur. In some examples, the network entity is caused to perform: determining that the potential radio link failure or handover failure is to occur for the communication device, wherein the determining is based on at least one of the following: an identity of a source cell associated with the communication device and an identity of a target cell ID for the communication device to handover to; a time series of downlink radio measurements performed by the communication device; L3 measurements performed at the cell level; L1 beam measurements; a sequence of serving cells or beams for the communication device; a number of cell or beam switches for the communication device; a time series associated with a location of the communication device overtime; a class for velocity associated with the communication device; an uplink angle of arrival associated with the communication device; a timing advance associated with the communication device; a maximum number of possible retransmissions for radio link control minus a re-transmission count for radio link control; or a time series of age of medium access control protocol data units at the time when they were successfully transmitted. In some examples, the network entity is caused to perform: when it is determined that the potential radio link failure or handover failure is to occur for the communication device, determining that the at least one neighbour cell is a candidate for re-establishment for the communication device, wherein the determining is based on at least one of the following: an identity of a source cell associated with the communication device and an identity of a target cell ID for the communication device to handover to; a time series of downlink radio measurements performed by the communication device; L3 measurements performed at the cell level; L1 beam measurements; a sequence of serving cells or beams for the communication device; a number of cell or beam switches for the communication device; a time series associated with a location of the communication device over time; a class for velocity associated with the communication device; an uplink angle of arrival associated with the communication device; a timing advance associated with the communication device; a maximum number of possible retransmissions for radio link control minus a re-transmission count for radio link control; or a time series of age of medium access control protocol data units at the time when they were successfully transmitted. In some examples, the network entity is caused to perform: providing, to the at least one neighbour cell, an indication of the contention free random access preamble associated with the least one neighbour cell that has been selected by the network entity. In some examples, the network entity is caused to perform: receiving, from the at least one neighbour cell, a notification that at least one contention-free random access channel preamble associated with the least one neighbour cell has been released. According to an eleventh aspect, there is provided a communication device comprising: means for providing, to a network entity, an indication of a warning of a potential radio link failure or handover failure to occur; means for receiving, from the network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; and means for performing a re-establishment with the at least one neighbour cell according to the configuration. According to an twelfth aspect, there is provided a method performed by a communication device, the method comprising: providing, to a network entity, an indication of a warning of a potential radio link failure or handover failure to occur; receiving, from the network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; and performing a re-establishment with the at least one neighbour cell according to the configuration. According to a thirteenth aspect, there is provided a communication device comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the communication device to perform: providing, to a network entity, an indication of a warning of a potential radio link failure or handover failure to occur; receiving, from the network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; and performing a re-establishment with the at least one neighbour cell according to the configuration. According to a fourteenth aspect, there is provided a computer program comprising instructions, which when executed by an apparatus, cause the apparatus to perform at least the following: providing, to a network entity, an indication of a warning of a potential radio link failure or handover failure to occur; receiving, from the network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; and performing a re-establishment with the at least one neighbour cell according to the configuration. According to a fifteenth aspect, there is provided a communication device comprising: circuitry configured to perform: providing, to a network entity, an indication of a warning of a potential radio link failure or handover failure to occur; receiving, from the network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; and performing a re-establishment with the at least one neighbour cell according to the configuration. The following are applicable to each (e.g., one or more, including all) of the above eleventh to fifteenth aspects. In some examples, a cell that is serving the communication device is provided by the network entity. In some examples, the network entity is a source or serving network entity for the communication device. In some examples, the at least one neighbour cell is neighbouring a cell that is serving the communication device. In some examples, the configuration indicates at least one of the following: a pool of resources for contention-free random access, wherein the pool of resources is common for a plurality of neighbour cells; a pool of resources that comprises at least one contention-free random access preamble, wherein the pool of resources is common for a plurality of neighbour cells; resources for contention-free random access associated with each of a plurality of neighbour cells; or at least one contention-free random access preamble associated with each of a plurality of neighbour cells. In some examples, the communication device is caused to perform: selecting a neighbour cell from the plurality of neighbour cells, wherein the performing the reestablishment comprises: performing the re-establishment with the neighbour cell that has been selected. In some examples, the configuration is received within one of the following: a radio resource control message, or a medium access control control element. In some examples, the re-establishment is performed based on a determination that a radio link failure or handover failure has occurred at the communication device. In some examples, the communication device is caused to perform: determining that the potential radio link failure or handover failure is to occur for the communication device, wherein the determining is based on at least one of the following: an identity of a source cell associated with the communication device and an identity of a target cell ID for the communication device to handover to; a time series of downlink radio measurements performed by the communication device; L3 measurements performed at the cell level; L1 beam measurements; a sequence of serving cells or beams for the communication device; a number of cell or beam switches for the communication device; a time series associated with a location of the communication device over time; a class for velocity associated with the communication device; a timing advance associated with the communication device; a maximum number of possible retransmissions for radio link control minus a re-transmission count for radio link control; or a time series of age of medium access control protocol data units at the time when they were successfully transmitted, wherein the indication is provided when the communication device has determined that the potential radio link failure or handover failure is to occur. In some examples, the communication device is caused to perform: when it is determined that the potential radio link failure or handover failure is to occur for the communication device, determining that the at least one neighbour cell is a candidate for reestablishment for the communication device, wherein the determining is based on at least one of the following: an identity of a source cell associated with the communication device and an identity of a target cell ID for the communication device to handover to; a time series of downlink radio measurements performed by the communication device; L3 measurements performed at the cell level; L1 beam measurements; a sequence of serving cells or beams for the communication device; a number of cell or beam switches for the communication device; a time series associated with a location of the communication device over time; a class for velocity associated with the communication device; a timing advance associated with the communication device; a maximum number of possible retransmissions for radio link control minus a re-transmission count for radio link control; or a time series of age of medium access control protocol data units at the time when they were successfully transmitted, wherein information related to the at least one neighbour cell being determined as a candidate for reestablishment is provided to the network entity with the indication. According to a sixteenth aspect, there is provided a network entity comprising: means for obtaining information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment; means for receiving, from the communication device, an indication of a warning of a potential radio link failure or handover failure to occur for the communication device; means for, based on the indication received from the communication device, providing, to the at least one neighbour cell, an indication of contention free random access resources associated with the least one neighbour cell for the communication device; and means for providing, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources for contention-free random access associated with the at least one neighbour cell. According to a seventeenth aspect, there is provided a method performed by a network entity, the method comprising: obtaining information related to resources for contention-free random access associated with at least one neighbour cell that are available for a reestablishment; receiving, from the communication device, an indication of a warning of a potential radio link failure or handover failure to occur for the communication device; based on the indication received from the communication device, providing, to the at least one neighbour cell, an indication of contention free random access resources associated with the least one neighbour cell for the communication device; and providing, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources for contention-free random access associated with the at least one neighbour cell. According to an eighteenth aspect, there is provided a network entity comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the network entity to perform: obtaining information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment; receiving, from the communication device, an indication of a warning of a potential radio link failure or handover failure to occur for the communication device; based on the indication received from the communication device, providing, to the at least one neighbour cell, an indication of contention free random access resources associated with the least one neighbour cell for the communication device; and providing, to a communication device, a configuration for contention-free random access for reestablishment, wherein the configuration indicates the resources for contention-free random access associated with the at least one neighbour cell. According to a nineteenth aspect, there is provided a computer program comprising instructions, which when executed by a network entity, cause the network entity to perform at least the following: obtaining information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment; receiving, from the communication device, an indication of a warning of a potential radio link failure or handover failure to occur for the communication device; based on the indication received from the communication device, providing, to the at least one neighbour cell, an indication of contention free random access resources associated with the least one neighbour cell for the communication device; and providing, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources for contention-free random access associated with the at least one neighbour cell. According to a twentieth aspect, there is provided a network entity comprising: circuitry configured to perform: obtaining information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment; circuitry configured to perform: receiving, from the communication device, an indication of a warning of a potential radio link failure or handover failure to occur for the communication device; circuitry configured to perform: based on the indication received from the communication device, providing, to the at least one neighbour cell, an indication of contention free random access resources associated with the least one neighbour cell for the communication device; and circuitry configured to perform: providing, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources for contention-free random access associated with the at least one neighbour cell. The following are applicable to each (e.g., one or more, including all) of the above sixteenth to twentieth aspects. In some examples, the network entity is caused to perform: selecting a preamble for contention-free random access associated with the at least one neighbour cell for the communication device, wherein the selecting is based on the information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment, wherein the indication of resources for contention free random access associated with the least one neighbour cell provided to the at least one neighbour cell comprises the preamble that has been selected. In some examples, the selecting of the preamble is performed based on the indication being received from the communication device. In some examples, the selecting of the preamble is performed in response to receiving the indication from the communication device. In some examples, the obtaining comprises one of: communicating with the at least one neighbour cell to determine the resources associated with the at least one neighbour cell that are available for a re-establishment; receiving, from the at least one neighbour cell, an indication of the resources associated with the at least one neighbour cell that are available for a re-establishment; or providing, to the at least one neighbour cell, a request for resources for contention-free random access for re-establishment; and receiving, from the at least one neighbour cell, an indication of resources for contention-free random access associated with the at least one neighbour cell that are available for a re-establishment. In some examples, the configuration indicates at least one of the following: a pool of resources for contention-free random access, wherein the pool of resources is common for a plurality of neighbour cells; a pool of resources that comprises at least one contention-free random access channel preamble, wherein the pool of resources is common for a plurality of neighbour cells; resources for contention-free random access associated with each of a plurality of neighbour cells; or at least one contention-free random access channel preamble associated with each of a plurality of neighbour cells. In some examples, the configuration is provided to the communication device within one of the following: a radio resource control message, a medium access control control element. In some examples, the network entity is caused to perform: when a potential radio link failure or handover failure is to occur for the communication device, selecting a contention free random access preamble associated with the least one neighbour cell, wherein the selecting is based on the information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment; wherein the resources associated with the at least one neighbour cell indicated in the configuration comprises the contention free random access preamble associated with the least one neighbour cell that has been selected by the network entity. In some examples, the network entity is caused to perform: receiving, from the at least one neighbour cell, a notification that at least one contention-free random access channel preamble associated with the least one neighbour cell has been released. A computer product stored on a medium may cause an apparatus to perform the methods as described herein. A non-transitory computer readable medium comprising program instructions, that, when executed by an apparatus, cause the apparatus to perform the methods as described herein. An electronic device may comprise apparatus as described herein. Various other aspects and further embodiments are also described in the following detailed description and in the attached claims. According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims. The embodiments that do not fall under the scope of the claims are to be interpreted as examples useful for understanding the disclosure. List of Abbreviations: AF: Application Function AMF: Access and Mobility Management Function AN: Access Network BHO: Baseline handover BS: Base Station CBRA: Contention-based random access CFRA: Contention-free random access CHO: Conditional handover CU: Centralised unit CN: Core Network DL: Downlink DU: Distributed unit eNB: eNodeB HOF: Handover failure gNB: gNodeB LTE: Long Term Evolution LTM: L1 / L2 triggered mobility MAC: Medium access control MS: Mobile Station ML: Machine learning NEF: Network Exposure Function NG-RAN: Next Generation Radio Access Network NF: Network Function NR: New Radio NRF: Network Repository Function NW: Network PCF Policy Control Function PLMN: Public Land Mobile Network RAN: Radio Access Network RF: Radio Frequency RLC: Radio link control RLF: Radio link failure RRC: Radio resource control RSRP: Reference signal received power RSRQ: Reference signal received quality SMF: Session Management Function TA: Timing advance UE: User Equipment UDR: Unified Data Repository UDM: Unified Data Management UL: Uplink UPF: User Plane Function 3GPP: 3rd Generation Partnership Project 5G: 5th Generation 5GC: 5G Core network 5G-AN: 5G Radio Access Network 5GS: 5G System Brief Description of Drawings Some examples will now be described, by way of illustrative and non-limiting example only, with reference to the accompanying drawings in which: FIG. 1 shows a schematic representation of a 5G communication system; FIG. 2 shows a schematic representation of an apparatus for the 5G communication system of FIG. 1; FIG. 3 shows a schematic representation of a communication device; FIG. 4 shows a schematic representation of a communication system with communication devices configured to perform re-establishment after handover failure; FIG. 5A shows a first example signalling and operations diagram between a communication device and network entities for a re-establishment procedure; FIG. 5B shows a second example signalling and operations diagram between a communication device and network entities for a re-establishment procedure; FIG. 6 shows a third example signalling and operations diagram between a communication device and network entities for a re-establishment procedure; FIG. 7 shows a fourth example signalling and operations diagram between a communication device and network entities for a re-establishment procedure; FIG. 7 shows a fifth example signalling and operations diagram between a communication device and network entities for a re-establishment procedure; FIG. 9 shows a sixth example signalling and operations diagram between a communication device and network entities for a re-establishment procedure; FIG. 10 shows a schematic representation of generation of an indication related to radio link failure or handover failure utilising an artificial intelligence model; FIG. 11 shows a schematic representation of a bitmap indication related to radio link failure or handover failure; FIG. 12 shows an example method flow diagram performed by an apparatus; FIG. 13 shows another example method flow diagram performed by an apparatus; FIG. 14 shows another example method flow diagram performed by an apparatus; FIG. 15 shows another example method flow diagram performed by an apparatus; and FIG 16 shows a schematic representation of a non-volatile memory medium storing instructions which when executed by a processor allow a processor to perform one or more of the steps of the method of FIGS. 12 to 15. Detailed Description A radio link failure (RLF) describes the event whereby a communication device (such as a user equipment (UE)) loses connectivity to its serving cell. A handover failure (HOF) describes the event whereby a communication device was ordered by its serving cell to connect to a neighbour cell, but fails to do so. RLF is declared in communication devices such as UEs according to mechanisms controlled by timer‘T310’ and counter ‘N310’, and in conjunction with timer ‘T311 ’ and counter N311’ (e.g., see 3GPP TS 38.331, section 7.1.1). For the counter N310, when there are consecutive indications of lower layers being out-of-sync (OoS), then a timer is started. When the timer expires, a radio resource control (RRC) re-establishment procedure is triggered. Stated differently, whenever a UE fails to decode physical downlink control channel (PDCCH) or physical downlink shared channel (PDSCH) due to a low received signal received power (RSRP) / reference signal receive quality (RSRQ), the UE indicates OoS to higher layer and starts counting number of events related to this in the N310 counter. If the UE detects N310 5 consecutive OoS indications for a configurable number of frames (e.g. 20 frames (200ms)), it starts the T310 timer while trying to get back in synchronisation with the network. If the T310 timer expires, the radio link is declared as failed and the UE requests radio resource control (RRC) connection re-establishment. If the UE detects N311 consecutive in-sync indications for another configurable number of frames (e.g. 10 frames (100ms)), prior to the T310 timer 10 expiring, then the timer is stopped, and the link has not failed. HOF is declared if after a certain time (given by the initial value of timer ‘T304’), a handover has not been completed. The expiry of timer ‘T304’ triggers an RRC reestablishment procedure. Table 1 below shows additional details for the timers identified above that are related 15 to RLF and HOF Timer Start Stop At expiry T304 Upon reception of RRCReconfiguration message including reconfiguration With Sync for the MCG which does not include sl-PathSwitchConfig, or upon reception of RRCReconfiguration message including reconfiguration With Sync for the SCG not indicated as deactivated in the NR or E-UTRA message containing the RRCReconfiguration message or upon conditional reconfiguration execution i.e. when applying a stored RRCReconfiguration message including reconfiguration With Sync. Also, for the MCG and SCG upon an indication from lower layer that an Upon successful completion of random access on the corresponding SpCell. In case of a reconfiguration with sync without performing random access procedure, upon receiving a PDCCH transmission addressed to C-RNTI after first UL transmission, for the same HARQ process. In case of an LTM cell switch without performing a random access procedure, upon receiving a PDCCH transmission addressed to C-RNTI after first UL transmission, for the same HARQ process. Upon receiving an indication from lower layers of successful completion of Rach-less handover. For T304 of SCG, upon SCG release. For T304 of MCG, in case of the handover from NR or intra-NR handover, or path switch from a L2 U2N Relay UE to a NR cell, or a reconfiguration with sync without performing random access procedure, or an LTM cell switch procedure, initiate the RRC re-establishment procedure; In case of handover to NR, perform the actions defined in the specifications applicable for the source RAT. If any DAPS bearer is configured and if there is no RLF in source PCell, initiate the failure information procedure. For T304 of SCG, inform network about LTM cell switch procedure is triggered and, for the MCG, upon performing an LTM cell switch procedure following cell selection performed while timer T311 is running. the reconfiguration with sync failure by initiating the SCG failure information procedure as specified in 5.7.3. T310 Upon detecting physical layer problems for the SpCell i.e. upon receiving N310 consecutive out-of-sync indications from lower layers. Upon receiving N311 consecutive in-sync indications from lower layers for the SpCell, upon receiving RRCReconfiguration with reconfigurationWithSync for that cell group, upon reception of MobilityFromNRCommand, upon the reconfiguration of rlf-TimersAndConstant, upon initiating the connection reestablishment procedure, upon conditional reconfiguration execution i.e. when applying a stored RRCReconfiguration message including reconfigurationWithSync for that cell group, and upon initiating the MCG failure information procedure. Upon SCG release, if the T310 is kept in SCG. If the T310 is kept in MCG: If AS security is not activated: go to RRC_IDLE else: initiate the MCG failure information procedure as specified in 5.7.3b or the connection reestablishment procedure as specified in 5.3.7 or the procedure as specified in 5.3.10.3 if any DAPS bearer is configured. If the T310 is kept in SCG, Inform E-UTRAN / NR about the SCG radio link failure by initiating the SCG failure information procedure as specified in 5.7.3. Table 1: Timers related to RLF and HOF for re-establishment procedures. RLF and RRC re-establishment may also be initiated when a maximum number of retransmissions are reached at RLC, as well as when a medium access control (MAC) layer 5 indicates a random access problem or beam failure recovery failure (e.g., see 3GPP TS 38.331 section 5.3.10). 3GPP TS 38.331 section 5.3.7 describes the procedure of RRC re-establishment. When performing a re-establishment, a UE (which has no longer a connection to a cell) selects a new cell to re-establish its connection. After cell selection, the UE establishes contact with 10 the new cell, and as part of the RRC re-establishment provides an identity (ID) of the previous cell and the ID of the UE in the previous cell to the network. The newly selected cell will attempt to retrieve the context of the UE from the previous serving cell of the UE. The UE context comprises the RRC configuration of the UE. If the context retrieval is successful, RRC reestablishment is performed. If the context retrieval is unsuccessful, RRC connection setup has 15 to be performed which will involve more signalling and is slower. Before a UE is able to signal the ID of the previous cell and the ID of the UE to the new cell, the UE synchronizes with the network on the physical level. This may be accomplished with contention based random access (CBRA), or contention free random access (CFRA). As part of CBRA, a UE transmits a randomly selected random access (RA) preamble to a base station (e.g., gNB) (also known as msg1). Multiple UEs may choose the same RA preamble and send the RA preamble to the base station. Therefore, there is possibility of contention or collision. After sending the preamble, the UE waits for a response from the gNB. The gNB transmits a random access response (RAR) to the UE (also known as msg2). The RAR comprises temporary cell radio network temporary identifier (TC-RNTI), timing advance (TA) and an uplink grant for msg3. The UE sends a scheduled transmission to the gNB (also known as msg3). The scheduled transmission may be an RRC message, such as RRC Connection setup or RRC re-establishment request. The gNB transmits contention resolution to the UE (also known as msg4). Msg 4 is the network confirming that the network has received the UE’s data, and assigning the UE its unique C-RNTI. Msg4 is received because, in principle, it may happen that another UE has also performed RACH (contending for access) and the UE cannot be sure that the network was replying in msg2 to itself or another UE. As part of CFRA, a gNB transmits a dedicated RA preamble assignment to a UE (also known as msgO). The UE transmits an RA preamble to the gNB according to the assignment (also known as msg1). The gNB transmits an RAR to the UE (also known as msg2). In this manner, in CFRA, the UE has been pre-configured with a specific RACH preamble. Thus, the contention resolution of msg4 of CBRA is not needed. The mg2 (RAR) of CFRA will already contain the C-RNTI for the UE. This access is considered faster because no contention resolution has to be performed. L1 / 2 Triggered Mobility (LTM) may be split into four phases, namely preparation, early synchronisation, execution and completion (e.g., see 3GPP TS 38.300, in section 9.2.3.5.2). Preparation: during which the serving centralised unit (CU) identifies the potential targets based on the L3 measurement reports, prepares the target cells and shares the target cell configurations with the UE. Early Synchronization: during which the serving distributed unit (DU) asks (considering L1 measurements) the UE to perform timing advance (TA) acquisition for a specific target cell. Execution: during which the serving DU decides (considering L1 measurements) on the target cell and asks the UE to switch to that. The latter switches to that cell and starts receiving data from it. Completion: during which the UE context is released from the prepared cells. This is optional and the UE context may be kept in case of dynamic switching. It is up to the CU on how long the UE context will be maintained. In scenarios whereby the UE maintains the configurations of the target cell, the UE is allowed to perform multiple / subsequent LTM operations. This is called subsequent LTM. Conditional handovers (CHO) were introduced in 3GPP Rei. 16 to ensure robustness of the handover procedure. In brief, in CHO, the serving cell prepares multiple target cells and the related conditional reconfigurations along with CHO execution conditions are provided beforehand to the UE, so as to ensure that the radio conditions are still adequate for the UE to receive the reconfiguration. Then the UE evaluates the CHO execution conditions and initiates the handover to a specific target cell once its corresponding CHO execution condition is met. A configured event triggers the UE to send a measurement report to a source node. Based on this report, the source node prepares one or more target cells for the handover (CHO Request + CHO Request Acknowledge) and then sends an RRC Reconfiguration (CHO command) to the UE. The UE evaluates the CHO execution conditions and accesses the target cell once one of the conditions expires. Once the UE completes the handover execution to the target cell (e.g., UE has sent RRC Reconfiguration Complete), the target cell sends to the source node “Handover Success” indication. Then, the source node stops transmissions to the UE and starts data forwarding the user plane packets to target cell. Moreover, the source node may release the CHO preparations in other target nodes / cells (which are no longer needed) when it receives “HO Success” indication. Artificial intelligence (Al) models (including machine learning (ML) models) may be utilised for mobility in 5G systems and beyond. The 3GPP Rel-19 study on AI / ML for mobility in NR(FS_NR__AIML_Mob) focussed on mobility enhancements in RRC connected mode over the air interface. In the study, both Al and / or ML models were considered at the UE-side and the network-side. The study considered whether there would be any potential benefits or gains when using Al or ML for mobility, and specifically in relation to HOF or RLF. A communication device (e.g., a UE) that has lost its connectivity to a serving network should re-establish the connection as soon as possible. Speeding up that process may be achieved by reserving RACH resources that are specific to the communication device. Reserved resources may allow the communication device to re-establish the connection in a contention-free way. Contention free re-establishment is often quicker and more efficient than a contention-based procedure. However, RACH resources are limited and cannot be reserved by default. Therefore, it may not be viable to reserve RACH resources for all active communication devices. Furthermore, not all communication devices that have an active connection will lose connectivity. In these cases, reserved RACH resources for reestablishment would not be used. This is an inefficient use of resources. One or more of the following examples aim to address one or more of the problems identified above. In examples, there is a method performed by a communication device (e.g., a UE). The method comprises receiving, from a network entity (e.g., a serving gNB), a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell. The method further comprises performing a re-establishment with the at least one neighbour cell according to the configuration. In examples, there is a method performed by a communication device (e.g., a UE). The method comprises providing, to a network entity (e.g., a serving gNB), an indication of a warning of a potential radio link failure or handover failure to occur. The method further comprises receiving, from the network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell. The method further comprises performing a re-establishment with the at least one neighbour cell according to the configuration. In some examples, there is provided a method for (fast) re-establishment that minimizes resource reservation (e.g., for(CFRA) RACH preambles). For example, the method includes, one or more network entities preparing resources for CFRA for re-establishment for a communication device (e.g., a UE). A serving network entity (e.g., serving gNB) determines that a potential RLF (or HOF) is to occur for the UE, and determines candidate gNBs that the UE may utilise for possible re-establishment. Alternatively, the UE determines that a potential RLF / HOF is to occur. In UE-based prediction of RLF / HOF, the UE selects resources for the re-establishment from a pool of resources that have been indicated to the UE by the serving gNB, and informs the serving gNB of the selection. The method further includes initiating, by the UE, a re-establishment according to CFRA using the selected resources (e.g., RA preamble), with a possible fallback to CBRA. The method further includes releasing any unused reserved resources. This example method will be described in more detail below. One or more of the following examples allow the identification of communication devices that are likely to lose connectivity. For example, those communication devices that have a higher likelihood of RLF or HOF. Furthermore, one or more of the examples lead to a determination of a time window in which such a failure is probable. Based on the identification of these ‘high risk’ device, RA resource reservation may be performed more efficiently (i.e., resources are reserved for communication devices that are more likely to use the resources for re-establishment, following a loss of connection). One or more of the examples allow the reserving of RA resources for multiple targets more efficiently. This may be achieved by minimising the amount of time that RA resources are reserved for in advance. These examples, alongside further examples, will be described in more detail below, alongside FIGS. 4 to 16. Before explaining the examples above in greater detail, an example communication device (as shown in FIG. 3) that is capable of performing a re-establishment with a network will be described. The communication device is part of a communication system (as shown in FIG. 1). The communication device is able to communicate with one or more of the entities of the communication system (as shown in FIG. 1) via an apparatus (as shown in FIG. 2), which may be part of / comprised in a base station. As described above, a base station and communication device may communicate with each other, such that the communication device is informed of RA resources that are reserved for re-establishment, such that the communication device is able to re-establish a connection with the network. Certain general aspects of the communication system and the communication device are briefly explained with reference to FIGS. 1 to 3 to assist in understanding the technology underlying the described examples. FIG. 1 shows a schematic representation of a 5G communication system 100. The wireless communication system 100 comprises one or more communication devices 102 such as user equipments (UEs), or terminals. The wireless communication system 100 comprises a 5G system (5GS). The 5GS comprises a 5G radio access network (5G-RAN) 106, a 5G core network (5GC) 104 comprising one or more network functions (NF), one or more application functions (AFs) 108, and one or more data networks (DNs) 110. The 5G-RAN 106 may comprise one or more gNodeB (gNB) distributed unit (DU) functions connected to one or more gNodeB (gNB) centralized unit (CU) functions. The 5GC 104 comprises an access and mobility management function (AMF) 112, a session management function (SMF) 114, an authentication server function (AUSF) 116, a user data management (UDM) 118, a user plane function (UPF) 120, a network exposure function (NEF) 122 and / or other NFs. Some of the examples as shown below may be applicable to 3GPP 5G standards. However, some examples may also be applicable to 5G-advanced, 4G, 3G and other 3GPP standards. In a wireless communication system 100, such as that shown in FIG. 1, communication devices 102, such as for example, terminals, user apparatuses, user equipments (UE), and / or machine-type communication devices are provided with wireless access via at least one base station or similar wireless transmitting and / or receiving node or point. The communication device 102 is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other devices. The communication device 102 may access a carrier provided by a base station or access point, and transmit and / or receive communications on the carrier. FIG. 2 illustrates an example of an apparatus 200. The apparatus 200 may be for the 5G communication system of FIG. 1. The apparatus 200 may be for controlling a function of one or more network entities and / or network functions, such as the entities of the 5G-RAN or the 5GC as illustrated on FIG. 1. The apparatus 200 comprises at least one random access memory (RAM) 211a, at least one read only memory (ROM) 211b, at least one processor 212, 213 and an input / output interface 214. The at least one processor 212, 213 is coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. The software code 215 may for example allow to perform one or more steps to perform one or more of the present aspects or examples. The software code 215 may be stored in the ROM 211b. The apparatus 200 may be interconnected with another apparatus 200 controlling another entity / function of the 5G-AN or the 5GC. . In some examples, apparatus 200 may be configured to provide one or more functions of the 5G-AN or the 5GC. For example, apparatus 200 may be configured to perform at least some functionality of a particular function of the 5G-AN or the 5GC. For example, apparatus 200 may be configured to operate as a particular function of the 5G-AN or the 5GC. In alternative examples, apparatus 200 may be configured to perform at least some functionality of two or more functions of the 5G-AN and / or the 5GC. For example, apparatus 200 may be configured to operate as two or more functions of the 5G-AN and / or the 5GC. The apparatus 200 may comprise one or more circuits, or circuitry (not shown) which may be configured to perform one or more of the present aspects or examples. FIG. 3 illustrates an example of a communication device 300. The communication device 300 may be similar to the communication device 102 illustrated in FIG. 1. The communication device 300 may be provided by any device capable of sending and receiving radio signals. Non-limiting examples of a communication device 300 are a user equipment, a terminal, a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, a Cellular Internet of things (CloT) device, or a terrestrial / maritime / aerial vehicle such as a car, a truck, a boat, an air plane, or a drone, or any combinations of these or the like. The communication device 300 may provide, for example, communication of data for carrying communications. The communications may be one or more of voice, electronic mail (email), text message, multimedia, data, machine data and so on. The communication device 300 may receive signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In FIG. 3, a transceiver apparatus is designated schematically by block 306. The transceiver apparatus 306 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device. The communication device 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The at least one processor 301 is coupled to the RAM 302b and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more of the present aspects. The software code 308 may be stored in the ROM 302a. The communication device 300 may comprise one or more circuits, or circuitry (not shown) which may be configured to perform one or more of the present aspects or examples. The processor, storage and other relevant control apparatus may be provided on an appropriate circuit board and / or in chipsets. This feature is denoted by reference 304. The communication device may optionally have a user interface such as keypad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of the device. FIG. 4 shows a schematic representation of a communication system with communication devices configured to perform re-establishment after handover failure. A first UE 401 (UE1) is located within a first cell 405 (celH). UE1 401 is being served by cell1 405. A second UE 403 (UE1) is located within a third cell 409 (cell3). UE2 403 is being served by cell3 409. UE1 401 is moving towards a fourth cell 411 (cell4), and so UE1 401 is to perform a handover to cell4 411. UE2 403 is also moving towards cell4 411 and is to perform a handover to cell4 411. Both UE1 401 and UE2 403 fail to handover to cell4 411 and lose connection to the network. UE1 401 and UE2 403 select a second cell 407 (cell) to recover to (establish a connection with). Using reserved RA resources, UE1 401 and UE2 403 are separately able to perform a re-establishment with cell2 407 in order to maintain connectivity with the network. As reserved RA resources are used, a contention-free procedure is used, which is a quicker procedure than contention-based. This is described in more detail in the signalling and operations diagrams of FIGS. 5 to 9. FIG. 5A shows a first example signalling and operations diagram between a communication device and network entities for a re-establishment procedure. The communication device may be a UE (and is herein referred to as UE1). There is also a further communication device (which is herein referred to as UE2). At S501a, a first gNB (gNB1), a second gNB (gNB2), and a third gNB (gNB3) communicate with each other to establish a pool (or group, or set) of resources for contention free RA (OFRA) for re-establishment, wherein the pool is common for gNB1, gNB2 and gNB3. In other examples, the pool of resources is common to gNB2 and gNB3, wherein gNB1 is the entity that uses / selects at least one resource from the pool. Resources (e.g., RA preambles) that are comprised in the pool may be available for the communication device for reestablishment. In some examples, resources in the pool are reserved (or available) for reestablishment. In this manner, the network entities (gNBs) prepare CFRA resources and provide corresponding information to neighbouring cells. gNB1 provides a cell that is serving the communication device at the time of S501a. gNB1 may be referred to as the ‘serving gNB’ or ‘source gNB’. gNB2 and gNB3 provide neighbour cells to the serving cell (of gNB1). A neighbour cell is a cell that is in proximity to the serving cell. Stated differently, a neighbour cell is a cell that is neighbouring the serving cell. gNB2 is a recovery candidate (RC) for UE1 and UE2. gNB3 is an RC for UE1 As an alternative to S501a, there are S501 to S504. At S501, gNB2 provides, to gNB1, an indication of a pool of resources (referred to as ‘pool2’) for CFRA for re-establishment. The resources in pool2 are resources for reestablishment that are available at gNB2. The resources in pool2 may comprise at least one RA preamble. Pool2 may be associated with a timer. The timer may be considered be a timer for validity. When the timer expires, the resources in pool2 may no longer be valid. In other examples, rather than a timer, pool2 is considered valid until a further message is provided to gNB1 with updated resources in pool2. At S502, gNB2 provides, to gNB3, an indication of the pool of resources (referred to as ‘pool2’) for CFRA for re-establishment. At S503, gNB3 provides, to gNB1, an indication of a pool of resources (referred to as ‘pool3’) for CFRA for re-establishment. The resources in pool3 are resources for reestablishment that are available at gNB3. The resources in pool3 may comprise at least one RA preamble. Pool3 may be associated with a timer. The timer may be considered be a timer for validity. When the timer expires, the resources in pool3 may no longer be valid. In other examples, rather than a timer, pool3is considered valid until a further message is provided to gNB1 with updated resources in pool3. At S504, gNB3 provides, to gNB2, an indication of the pool of resources (referred to as ‘pool3’) for CFRA for re-establishment. In the example of FIG. 5A it is assumed that alternative 2 has been selected, i.e., S501 to S504 have occurred. At S505, UE1 sends, to gNB1, a measurement report. The measurement report may be sent periodically by UE1. In other examples, the measurement report is sent due to a determined event (i.e., event-based reporting). At S506, based on the measurement report, an evaluation for a potential handover (HO) is triggered atgNBI. A measurement event or an internal threshold of reports may trigger the HO evaluation. At S507, a potential RLF or HOF is predicted to occur for UE1. gNB1 may determine that the potential RLF or HOF is to occur for UE1. For example, gNB1 may utilise an Al (or ML) model for determining that a potential RLF or HOF may occur. Any suitable Al or ML model may be utilised. An example Al model is described in more detail below alongside FIG. 10 and FIG. 11. Re-establishment candidates for UE1 are also determined. In this example, gNB2 and gNB3 are determined as candidates for re-establishment for UE1. The candidates may be determined by gNB1. The candidates may be determined using the Al or ML model that determined that the potential RLF or HOF is to occur. In other examples, the gNB1 utilises a separate Al or ML model to determine the candidates. This will be described in more detail below, with an example Al model described alongside FIG. 10 and FIG. 11. At S508, gNB1 selects (or determines) at least one resource for OFRA for reestablishment for each candidate. In this example, the candidates are gNB2 and gNB3, and so at least one resource is selected from pool2 and pool3. In this example, gNB1 selects an RA preamble from pool2, and selects an RA preamble from pool3. The selected RA preambles are for UE1 for a potential re-establishment. For example, if the measurement report (of S505) indicates that UE1 should handover to cell 4 of gNB4, and the prediction determines cell 2 of gNB2 and cell 3 of gNB3 as suitable recovery targets, gNB1 selects an RA preamble from the respective pool for UE1. For example, gNB2 provides pool2 with preambles (F1, F2), and gNB3 provides pool3 with preambles (F2, F3) to gNB1. gNB1 picks F1 as RA preamble for cell2 and F2 as preamble for cell3. If the resource pools 1 to 3 are overlapping (i.e., overlapping RA preambles), gNB1 may select an RA preamble that is common to all pools, saving signalling to UE1. At S509, gNB1 informs gNB2 about the selected RA preamble from pool2 (for UE1). For example, RA preamble F1 has been selected from pool2. At S510, gNB1 informs gNB3 about the selected RA preamble from pool3 (for UE1). For example, RA preamble F2 has been selected from pool3. At S511, in a similar manner to S508, gN3 selects at least one RA preambles, for UE2, from pool2. gNB3 provides the serving cell for UE2. gNB2 is a recovery candidate for UE2 for a re-establishment. At S512, gNB3 informs gN2 about the selected RA preamble from pool 2 (for UE2). AtS513a, gNB1 sends, to UE1, a configuration (or configuration information) forCFRA for re-establishment. The configuration indicates the selected resources (RA preambles) for CFRA associated with gNB2 and gNB3. In other examples, the configuration indicates resources for CFRA associated with a (single) gNB. The configuration may be sent within RRC signalling to UE1. In other examples, the configuration is comprises in a medium access control control element (MAC CE). As an alternative to S513a, there is S513b. AtS513b, gNB1 sends, to UE1, a configuration (or configuration information) for CFRA for re-establishment. The configuration indicates the selected resources (RA preambles) for CFRA associated with gNB2 and gNB3. In other examples, the configuration indicates resources for CFRA associated with a (single) gNB. The configuration is sent in a message for RRC reconfiguration (RRCReconfiguration) for handover. The message may indicate a HO from gNB1 to a fourth gNB (gNB4). gNB4 may be referred to as a target gNB. Stated differently, gNB1 sends a HO command (to gNB4) to UE1. The HO command includes the selected resources for re-establishment for gNB2 and gNB3 This is different from a CHO in that minimal target information, rather than a complete target RRC configuration, is provided to UE1. This has the advantage of reduced target preparation. A difference between S513a and S513b is that, in S513a, the configuration for CFRA re-establishment is sent in a message for the purpose of re-establishment (only). Whereas, for S513b, the message is a combined HO command (for HO to gNB4) and CFRA for reestablishment in the case of failure. At S514, an RLF or HOF occurs. In this examples, an RLF for UE1 occurs. At S515, UE1 selects gNB2 (from gNB2 and gNB3) for re-establishment. At S516, UE1 uses the RA preamble (from pool2) to communicate with gNB2 in an attempt to establish a connection with gNB2. Stated differently, UE1 triggers a random access procedure with gNB2 using the selected preamble (e.g., RA preamble F1) from pool2. At S517, when a single gNB used the RA preamble (as used by UE1) from pool2, then CFRA is performed between UE1 and gNB2. Else, contention resolution is provided in an RA response (RAR) to UE1. Stated differently, when no other cell has allocated the same CFRA re-establishment preamble to one of its UEs for the same candidate cell, then CFRA re-establishment will succeed. When another cell allocates the same CFRA re-establishment preamble for the same candidate cell, the candidate cell knows that there may be a preamble collision in case the UEs from the different source cells re-establish at the same time. Therefore the candidate cell will treat the CFRA preamble as CBRA and inform the UE in the RAR message to perform contention resolution in msg3. Alternatively, candidate tells UE in random access response (RAR) to fall back to CBRA. At S518, gNB2 provides, to gNB1, a notification that at least one RA preamble for UE1 has been released. The notification may be that the selected RA preamble from pool2 has been released. Stated differently, after UE1 has established a connection to cell 2 of gNB2, cell 2 / gNB2 may inform cell 1 / gNB1 that the RA resource for UE1 may be released. This allows cell 1 / gNB1 to allocate the RA preamble to another UE in the future. At S519, there is a time-out for the selected RA preamble for UE2 at gNB2. This may be due to a re-establishment attempt for UE2 not occurring within a threshold time. For example, when the RA preamble for UE2 is selected, this triggers a timer to start. When the timer expires, the time-out for the RA preamble occurs. At S520, there is a time-out for the selected RA preamble for UE2 at gNB3. It should be understood that, in some examples, one or more of the steps in FIG. 5a may not be performed, or may be performed in a different order. For example, the preparation of CFRA resources for re-establishment by the gNBs may be performed after the potential RLF or HOF has been predicted. This is depicted in FIG. 5B. FIG. 5B shows a second example signalling and operations diagram between a communication device and network entities for a re-establishment procedure. A difference between FIG. 5B (compared to FIG. 5A) is the order in which the signalling occurs. FIG. 5B uses the same labelling of method steps as are used in FIG. 5A. In FIG. 5B, S505 to S507 occurs before S501a, or S501 to S504. Following S501a, or S501 to S504, there is S508. In this manner, in the example of FIG. 5B, the pools of resources are not determined by the gNBs until after the potential RLF or HOF has been determined to occur. In some examples, S501a, or S501 to S504 may be triggered by a request being sent by gNB1 for resources for re-establishment for UE1 (not shown). FIG. 6 shows a third example signalling and operations diagram between a communication device and network entities for a re-establishment procedure. FIG. 6 has the same signalling and operations as shown in either of FIG. 5A or 5B, with changes made to S513a / S513b only. In FIG. 6, the alternative implementation of S513a / S513b is shown in S613. In the alternative implementation of FIG. 6, the selected RA preambles for gNB2 and gNB3 to be used for re-establishment are sent to UE1 using a MAC CE from a serving distributed unit (DU) of gNB1. The serving DU obtains the RA preambles from a centralised unit (CU). For example, by using a UE context modification request (for UE1). The MAC CE may be a MAC CE comprising information in rach-ReestablishmentConfigDedicated. In other examples, gNB1 provides a set of RA resources via RRCReconfiguration, and the MAC CE provides indices to those RA resources. This would reduce the size of the MAC CE. This signalling is depicted in FIG. 6. At S613a, a DU of gNB1 (DU1) provides, to a CU of gNB1 (CU1), a request for RA resources for re-establishment. At S613b, based on the request, CU1 provides an indication of the RA resources to DU1. At S613c, DU1 provides, to UE1, a MAC CE comprising the RA resources (e.g., RA preambles) for gNB2 and gNB2 for re-establishment. The signalling and operations shown in FIG. 5A, FIG. 5B, and FIG. 6 assume that an RLF or HOF does occur for UE1. A scenario whereby an RLF or HOF does not occur for UE1 is depicted in FIG. 7. FIG. 7 shows a fourth example signalling and operations diagram between a communication device and network entities for a re-establishment procedure. FIG. 7 has the same signalling and operations as FIG. 5A from S501 a through to S513b. The method steps that are common between FIG. 5A and FIG.7 have the same labelling used. S501a to S513b are the same as described above. At S714, at gNB1, there is a time-out for the RA preamble for UE1. The time-out may based on the expiry of a timer associated with the RA preamble. As the timer has expired before an RLF or HOF has occurred at the UE1, there is the time-out. At S715, at gNB2, there is a time-out for the RA preambles for UE1 and UE2. The time-out may based on the expiry of timers associated with the RA preambles. As the timers expired before an RLF or HOF has occurred at the UE1 and UE2, there are time-outs. At S716, at gNB3, there is a time-out for the RA preamble for UE2. The time-out may based on the expiry of a timer associated with the RA preamble. As the timer has expired before an RLF or HOF has occurred at the UE2, there is the time-out. A similar time-out may occur if UE1 were to (successfully) handover to the target gNB4. Alternatively, a new gNB (such as gNB4 or other reselected gNB) informs gNB2 about the RA resources which may be released. In the examples of FIG. 5A, FIG. 5B, FIG. 6 and FIG. 7, the determination (or prediction) of a potential RLF or HOF to occur is performed by the network. In other examples, the determination (or prediction) may be performed on the UE-side. This is described in more detail alongside FIGS. 8 to 9. FIG. 8 shows a fifth example signalling and operations diagram between a communication device and network entities for a re-establishment procedure. The communication device may be a UE (and is herein referred to as UE1). There is also a further communication device (which is herein referred to as UE2). At S801a, a first gNB (gNB1), a second gNB (gNB2), and a third gNB (gNB3) communicate with each other to establish a pool (or group, or set) of resources for contention free RA (CFRA) for re-establishment, wherein the pool is common for gNB1, gNB2 and gNB3. In other examples, the pool of resources is common to gNB2 and gNB3, wherein gNB1 is the entity that uses / selects at least one resource from the pool. Resources (e.g., RA preambles / CFRA preambles) that are comprised in the pool may be available for UE1 for reestablishment In some examples, resources in the pool are reserved for re-establishment. In other examples, resources in the pool are not reserved, but are available to be used for reestablishment. In this manner, the network entities (gNBs) prepare CFRA resources and provide corresponding information to neighbouring cells. gNB1 provides a cell that is serving the communication device at the time of S801a. gNB1 may be referred to as the ‘serving gNB’ or ‘source gNB’. gN2 and gNB3 provide neighbour cells to the serving cell (of gNB1). A neighbour cell is a cell that is in proximity to the serving cell. Stated differently, a neighbour cell is a cell that is neighbouring the serving cell. gNB2 is a recovery candidate (RC) for UE1 and UE2. gNB3 is an RC for UE1. As an alternative to S801a, there are S801 to S804. At S801, gNB2 provides, to gNB1, an indication of a pool of resources (referred to as ‘pool2’) for CFRA for re-establishment. The resources in pool2 are resources for reestablishment that are available at gNB2. The resources in pool2 may comprise at least one RA preamble. Pool2 may be associated with a timer. The timer may be considered be a timer for validity. When the timer expires, the resources in pool2 may no longer be valid. In other examples, rather than a timer, pool2 is considered valid until a further message is provided to gNB1 with updated resources in pool2. At S802, gNB2 provides, to gNB3, an indication of the pool of resources (referred to as ‘pool2’) for CFRA for re-establishment. At S803, gNB3 provides, to gNB1, an indication of a pool of resources (referred to as ‘pool3’) for CFRA for re-establishment. The resources in pool3 are resources for reestablishment that are available at gNB3. The resources in pool3 may comprise at least one RA preamble. Pool3 may be associated with a timer. The timer may be considered be a timer for validity. When the timer expires, the resources in pool3 may no longer be valid. In other examples, rather than a timer, pool3 is considered valid until a further message is provided to gNB1 with updated resources in pool3. At S804, gNB3 provides, to gNB2, an indication of the pool of resources (referred to as ‘pool3’) for CFRA for re-establishment. In the example of FIG. 8 it is assumed that alternative 2 has been selected, i.e., S801 to S804 have occurred. At S805, a potential RLF or HOF is predicted to occur for UE1. UE1 may determine that the potential RLF or HOF is to occur at UE1. For example, UE1 may utilise an Al (or ML) model for determining that the potential RLF or HOF may occur. Any suitable Al or ML model may be utilised. An example Al model is described in more detail below alongside FIG. 10 and FIG. 11. At S806, UE1 provides, to gNB1, an indication of a warning of a potential RLF or HOF to occur. For example, the indication may be a flag (e.g., 1-bit flag), or other suitable indication. gNB1 (and other gNBs) may be configured to interpret the flag as an indication of a potential RLF or HOF. In this manner, the indication (or warning) originates from UE1. The indication may include additional inputs for selecting cells for re-establishment. The indication may be an RRC message (can easily carry more information), or a MAC CE message (can be sent quickly), or L1 UCI indication. At S807, gNB1 selects (or determines) at least one resource for CFRA for reestablishment for each candidate. In this example, the candidates for re-establishment are gNB2 and gNB3. In this example, gNB1 selects an RA preamble from pool2, and selects an RA preamble from pool3. The selected RA preambles are for UE1 for a potential re-establishment. For example, gNB2 provides pool2 with preambles (F1, F2), and gNB3 provides pool3 with preambles (F2, F3) to gNB1. gNB1 picks F1 as RA preamble for cell2 and F2 as preamble for cell3. If the resource pools 1 to 3 are overlapping (i.e., overlapping RA preambles), gNB1 may select an RA preamble that is common to all pools, saving signalling to UE1. At S808, gNB1 informs gNB2 about the selected RA preamble from pool2 (for UE1). For example, RA preamble F1 has been selected from pool2. At S809, gNB1 informs gNB3 about the selected RA preamble from pool3 (for UE1). For example, RA preamble F2 has been selected from pool3. At S810, in a similar manner to S807, gN3 selects at least one RA preambles, for UE2, from pool2. gNB3 provides the serving cell for UE2. gNB2 is a recovery candidate for UE2 for a re-establishment. At S811, gNB3 informs gN2 about the selected RA preamble from pool 2 (for UE2). At S812, gNB1 sends, to UE1, a configuration (or configuration information) for CFRA for re-establishment. The configuration indicates the selected resources (RA preambles) for CFRA associated with gNB2 and gNB3. In other examples, the configuration indicates resources for CFRA associated with a (single) gNB. The configuration may be sent within RRC signalling to UE1. In other examples, the configuration is comprises in a medium access control control element (MAC CE). In other examples, the configuration is sent in a message for RRC reconfiguration (RRCReconfiguration) (e.g., for handover). The message may indicate a HO from gNB1 to a fourth gNB (gNB4). gNB4 may be referred to as a target gNB. At S813, an RLF or HOF occurs. In this examples, an RLF for UE1 occurs. At S814, UE1 selects gNB2 (from gNB2 and gNB3) for re-establishment. At S815, UE1 uses the RA preamble (from pool2) to communicate with gNB2 in an attempt to establish a connection with gNB2. Stated differently, UE1 triggers a random access procedure with gNB2 using the selected preamble (e.g., RA preamble F1) from pool2. At S816, when a single gNB used the RA preamble (as used by UE1) from pool2, then CFRA is performed between UE1 and gNB2. Else, contention resolution is provided in an RA response (RAR) to UE1. Stated differently, when no other cell has allocated the same CFRA re-establishment preamble to one of its UEs for the same candidate cell, then CFRA re-establishment will succeed. When another cell allocates the same CFRA re-establishment preamble for the same candidate cell, the candidate cell knows that there may be a preamble collision in case the UEs from the different source cells re-establish at the same time. Therefore the candidate cell will treat the CFRA preamble as CBRA and inform the UE in the RAR message to perform contention resolution in msg3. Alternatively, candidate tells UE in random access response (RAR) to fall back to CBRA. At S817, gNB2 provides, to gNB1, a notification that at least one RA preamble for UE1 has been released. The notification may be that the selected RA preamble from pool2 has been released. Stated differently, after UE1 has established a connection to cell 2 of gNB2, cell 2 / gNB2 may inform cell 1 / gNB1 that the RA resource for UE1 may be released. This allows cell 1 / gNB1 to allocate the RA preamble to another UE in the future. At S818, there is a time-out for the selected RA preamble for UE2 at gNB2. This may be due to a re-establishment attempt for UE2 not occurring within a threshold time. For example, when the RA preamble for UE2 is selected, this triggers a timer to start. When the timer expires, the time-out for the RA preamble occurs. At S819, there is a time-out for the selected RA preamble for UE2 at gNB3. FIG. 9 shows a sixth example signalling and operations diagram between a communication device and network entities for a re-establishment procedure. The communication device may be a UE (and is herein referred to as UE1). There is also a further communication device (which is herein referred to as UE2). At S901, a first gNB (gNB1), a second gNB (gNB2), and a third gNB (gNB3) communicate with each other to establish a pool (or group, or set) of resources for contention free RA (CFRA) for re-establishment, wherein the pool is common for gNB1, gNB2 and gNB3. In other examples, the pool of resources is common to gNB2 and gNB3, wherein gNB1 is the entity that uses / selects at least one resource from the pool. Resources (e.g., RA preambles / CFRA preambles) that are comprised in the pool may be available for UE1 for reestablishment. In some examples, resources in the pool are reserved for re-establishment. In other examples, resources in the pool are not reserved, but are available to be used for reestablishment. In this manner, the network entities (gNBs) prepare CFRA resources and provide corresponding information to neighbouring cells. gNB1 provides a cell that is serving the communication device at the time of S801a. gNB1 may be referred to as the ‘serving gNB’ or ‘source gNB’. gN2 and gNB3 provide neighbour cells to the serving cell (of gNB1). A neighbour cell is a cell that is in proximity to the serving cell. Stated differently, a neighbour cell is a cell that is neighbouring the serving cell. gNB2 is a recovery candidate (RC) for UE1 and UE2. gNB3 is an RC for UE1. As an alternative to S901, there are S901a to S901d. At S901a, gNB2 provides, to gNB1, an indication of a pool of resources (referred to as ‘pool2’) for CFRA for re-establishment. The resources in pool2 are resources for reestablishment that are available at gNB2. The resources in pool2 may comprise at least one RA preamble. Pool2 may be associated with a timer. The timer may be considered be a timer for validity. When the timer expires, the resources in pool2 may no longer be valid. In other examples, rather than a timer, pool2 is considered valid until a further message is provided to gNB1 with updated resources in pool2. At S901b, gNB2 provides, to gNB3, an indication of the pool of resources (referred to as ‘pool2’) for CFRA for re-establishment. At S901c, gNB3 provides, to gNB1, an indication of a pool of resources (referred to as ‘pool3’) for CFRA for re-establishment. The resources in pool3 are resources for reestablishment that are available at gNB3. The resources in pool3 may comprise at least one RA preamble. Pool3 may be associated with a timer. The timer may be considered be a timer for validity. When the timer expires, the resources in pool3 may no longer be valid. In other examples, rather than a timer, pool3 is considered valid until a further message is provided to gNB1 with updated resources in pool3. At S901d, gNB3 provides, to gNB2, an indication of the pool of resources (referred to as ‘pool3’) for CFRA for re-establishment. In the example of FIG. 9 it is assumed that alternative 1 has been selected, i.e., S901 has occurred. At S902, gNB1 sends, to UE1, a configuration (or configuration information) for CFRA for re-establishment. The configuration indicates the pool of RA resources (e.g., RA preambles) that are common for the gNBs. In other examples, the configuration indicates the selected resources (RA preambles) for CFRA associated with gNB2 and gNB3. In other examples, the configuration indicates resources for CFRA associated with a (single) gNB. At S903, a potential RLF or HOF is predicted to occur for UE1. UE1 may determine that the potential RLF or HOF is to occur at UE1. For example, UE1 may utilise an Al (or ML) model for determining that the potential RLF or HOF may occur. Any suitable Al or ML model may be utilised. An example Al model is described in more detail below alongside FIG. 10 and FIG. 11. UETs prediction may be triggered alongside an A3 measurement report. At S904, UE1 selects at least one RA preamble from the pool of resources (received in S902). The selection of the at least one RA preamble is based on the determination of the potential RLF or HOF. For example, the pool of (common) resources comprises RA preambles F1, F2 and F3. UE1 selects RA preamble F1, wherein RA preamble F1 is common to all cells. At S905, UE1 provides, to gNB1, an indication of a warning of a potential RLF or HOF to occur. UE1 also indicates the at least one RA preamble that has been selected by UE1. For example, UE1 may indicate that RA preamble F1 has been selected. At least part of the indication may be a flag (e.g., 1 -bit flag), or other suitable indication. gNB1 (and other gNBs) may be configured to interpret the flag as an indication of a potential RLF or HOF. In this manner, the indication (or warning) originates from UE1. The indication may include additional inputs for selecting cells for re-establishment. The indication may be an RRC message (can easily carry more information), or a MAC CE message (can be sent quickly), or an L1 UCI indication. At S906, gNB1 informs gNB2 about the selected RA preamble from the pool of resources (for UE1). For example, RA preamble F1 has been selected. At S907, gNB1 informs gNB3 about the selected RA preamble from the pool of resources (for UE1). For example, RA preamble F2 has been selected. At S908, in a similar manner to S905, UE2 provides, to gNB3, an indication of a warning of a potential RLF or HOF to occur. UE2 also indicates at least one RA preamble that has been selected by UE2. At S909, gNB3 informs gN2 about the at least one RA preamble that has been selected by UE2. At S910, gNB1 sends, to UE1, a command to handover to a fourth gNB (gNB4). For example, gNB1 sends an RRCReconfiguration message to UE1, which indicates that UE1 should handover to gNB4. In this example, the command to HO is lost, or not received by UE1. At S911, an RLF or HOF occurs. In this examples, an RLF for UE1 occurs. At S912, UE1 selects gNB2 (from gNB2 and gNB3) for re-establishment. At S913, UE1 uses the RA preamble (e.g., RA preamble F1) to communicate with gNB2 in an attempt to establish a connection with gNB2. Stated differently, UE1 triggers a random access procedure with gNB2 using the selected preamble (e.g., RA preamble F1). At S914, when a single gNB used the RA preamble (as used by UE1) from the common pool, then CFRA is performed between UE1 and gNB2. Else, contention resolution is provided in an RA response (RAR) to UE1. Stated differently, when no other cell has allocated the same CFRA re-establishment preamble to one of its UEs for the same candidate cell, then CFRA re-establishment will succeed. When another cell allocates the same CFRA re-establishment preamble for the same candidate cell, the candidate cell knows that there may be a preamble collision in case the UEs from the different source cells re-establish at the same time. Therefore the candidate cell will treat the CFRA preamble as CBRA and inform the UE in the RAR message to perform contention resolution in msg3. Alternatively, candidate tells UE in random access response (RAR) to fall back to CBRA. At S915, there is a time-out for the selected RA preamble for UE2 at gNB2. This may be due to a re-establishment attempt for UE2 not occurring within a threshold time. For example, when the RA preamble for UE2 is selected, this triggers a timer to start. When the timer expires, the time-out for the RA preamble occurs. In this manner, in the example of FIG.9, it is the UE (i.e., UE1) that performs the selection of RA preambles and informs those to the network. Further signalling from the network to UE1 is not required after the RLF warning. Stated differently, the loss of the HO command in S910 does not affect the CFRA re-establishment. Multiple UEs served by the same source gNB (e.g., gNB1) may select the same RA preamble for re-establishment from the common pool, and then report the selected RA preamble to the source gNB. When multiple UEs have selected the same RA preamble, the source gNB may signal one or more of the multiple UEs to select another preamble. Alternatively, the source gNB may inform the candidate gNB(s) for re-establishment of the selected RA preambles without signalling the UEs (i.e., there may be contention if more than one UE has an RLF or HOF). The release of the resources (e.g., preambles) in this example of FIG. 9 may be limited to the target cell (e.g., gNB4). Rather than a release of resources (e.g., preambles), the serving gNB may determine to maintain / keep the pool of resources for a future use by the UE. As described above, an Al or ML model may be utilised by a UE or a network entity (e.g., a gNB) to determine whether a potential RLF or HOF may occur for a UE. Furthermore, the most suitable candidate cells and / or resources may be determined utilising an Al or ML model. An example Al model which may be utilised by a UE or network entity is described alongside FIG. 10 and FIG. 11. FIG. 10 shows a schematic representation of generation of an indication related to radio link failure or handover failure utilising an artificial intelligence model. The Al model 1000 (which may be an ML model), as depicted in FIG. 10, may be trained to predict, from selected inputs, whether a handover that is being prepared may lead to a failure (e.g., HOF / RLF). This may be a binary classifier, wherein the input features may include at least one of the following: an identity (ID) of a source cell, an ID of a (target) candidate cell, a time series of DL radio measurements performed by a UE (e.g., measured RSRP, RSRQ and / or SINR), L3 measurements (e.g., at the cell-level), L1 beam measurements (e.g., at the cell-level), a sequence of previous serving cells (or beams), a number of cell (or beam) switches, a time series indicating the location of a UE, a velocity class of a UE, and UL angle of arrival (AoA) and timing advance (TA) for a UE, radio link control (RLC) maximum possible retransmissions minus RLC re-transmission count, a time series of the age of MAC PDUs at the time when they were successfully transmitted. When training of the Al model 1000 is performed on the network-side, the input(s) may be restricted to DL transmissions. When training of the Al model 1000 is performed on the UE-side, the input(s) may be restricted to UL transmissions. To train the Al model 100, the input data may be collected at handover preparation and labelled based on the occurrence of RLFs / HOFs. In case of RLF prediction related to a handover, the labelling is based on the HO success. Class imbalance may be expected (failures are rare), and so training dataset balancing may be performed. At inference, the Al model 1000 outputs, from an input sample, a probability that a handover that is being prepared will lead to a failure (e.g., HOF / RLF). The probability (or prediction) may be used to determine whether resources should be reserved for the potential re-establishment. A further Al model may be trained to predict which cells, and potentially also which beams, are the most suitable for the UE to perform a re-establishment with. To train the further Al model, which may be multi-class classification ML model, the input features as described above may also be used. In the labelling of the input for the further Al model, IDs for cells (or beams) after a re-establishment may be utilised. This further Al model may be trained with samples from failed handovers (only), in some examples. At inference of the further Al model, the predicted cell (or beams) may be used to optimize where the CFRA resources should be allocated. It should be understood that in other examples, the Al model 1000 and the further Al model may be the same. Stated differently, a suitable Al model may be utilised that both determines a probability of a potential RLF / HOF, and also predicts suitable cells (or beams) for a re-establishment. As shown in FIG. 10, there is an implementation example to show the Al model 1000 structure layout, with both input and output data frame structure. As described above, at least one of a number of different input metrics may be used to train an Al model. In this example, radio measurements including RSRP, RSRQ, and CQI are used as inputs from the past / V milliseconds (ms). There is a measurement time window 1001 in which measurements may be performed or obtained (e.g., RSRP, RSRQ, and CQI measurements). The measurements form an input window 1003 for the Al model 1000. The input window 1003 is split into an RSRP input, an RSRQ input, and a CQI input, in this example. The input window 1003 feeds into long shortterm memory (LSTM) layers 1005. The LSTM layers 1005 feed into fully connected layers 1007. The fully connected layers 1007 feed into a binary classifier / support vector model 1009. From the binary classifier layer 1009, an output 1011 is provided. The output 1011 may be a probability of an RLF or HOF. The output 1011 may be directly linked to the failure status (e.g., RLF or HOF status) from binary classification (i.e., 0 or 1) for the future P ms time step. The data labelling for training of the Al model 1000 may be based on the status of T310 timer. If T310 timer is triggered, a UE starts to collect radio measurements 1001 for the input and failure status 0 or 1 may be evaluated based on the failure report when T310 timer is expired. By modelling the output 1011 in this manner, a simple 1-bit may be used to build the RLF warning message via lower layer signalling. Alternatively, the output layer may be further designed with a softmax function that delivers a probabilistic value to show the prediction accuracy. The probabilistic value may be quantised to more compact Q-bits information for a MAC CE, as shown in FIG. 11. FIG. 11 shows a schematic representation of a bitmap indication related to radio link failure or handover failure. The output 1011 (from FIG. 10), which may be a binary 1 or 0, is passed to a softmax function 1101. A softmax function converts a vector of K real numbers into a probability distribution of K possible outcomes. It is a generalization of the logistic function to multiple dimensions, and used in multinomial logistic regression. The softmax function is often used as the last activation function of a neural network to normalize the output of a network to a probability distribution over predicted output classes. The softmax function 1101 provides a probabilistic value which shows an accuracy of the prediction (of an RLF / HOF). The probabilistic value is provided to a postprocessing block 1103. The postprocessing block 1103 takes the probabilistic value as an input to a quantiser 1105. An output of the quantiser 1105 is a bitmap 1107. The bitmap 1107 is compact Q-bits information, which may be suitable for a MAC CE. The compact information means the bitmap comprising the prediction has an amount of data that is suitable for being sent in a MAC CE. It should be understood that the Al models and functions described in FIG. 10 and FIG. 11 are given as examples only. Any suitable Al model or ML model may be used to predict or determine potential RLF or HOF for UEs. One or more of the examples described above have the advantage that the procedure for re-establishment is improved. A UE is able to perform a re-establishment more quickly due to the known availability of RA resources, which the UE is able to use for contention-free RA. In some scenarios, RA resources (e.g., preambles) may be limited. One or more of the examples described above identify UEs that are more likely to use resources for reestablishment (e.g., due to an RLF or HOF). UEs that have been identified for potential RLF or HOF may be provided with configurations that identify resources for CFRA. In this manner, a method for re-establishment that is both quicker, and more resource efficient, is provided. FIG. 12 shows an example method flow performed by an apparatus. The apparatus may be a communication device. Examples of communication devices include a UE, a terminal, a mobile device, etc. In S1201, the method comprises: receiving, from a network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; and In S1203, the method comprises: performing a re-establishment with the at least one neighbour cell according to the configuration. It should be understood that, in some examples, one or more additional method steps are included in the method flow of FIG. 12 and are performed by the apparatus. In some examples, one or more of the method steps of FIG. 12 detailed above may not be performed, or may be performed in a different order. FIG. 13 shows an example method flow performed by an apparatus. The apparatus may be a network entity. For example, the network entity may be a base station (e.g., gNB). In some examples, the apparatus is an gNB that provides a cell that serves a communication device. In S1301, the method comprises: obtaining information related to the resources associated with at least one neighbour cell that are available for a re-establishment. In S1301, the method comprises: providing, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources associated with the at least one neighbour cell. It should be understood that, in some examples, one or more additional method steps are included in the method flow of FIG. 13 and are performed by the apparatus. In some examples, one or more of the method steps of FIG. 13 detailed above may not be performed, or may be performed in a different order. FIG. 14 shows an example method flow performed by an apparatus. The apparatus may be a communication device. Examples of communication devices include a UE, a terminal, a mobile device, etc. In S1401, the method comprises: providing, to a network entity, an indication of a warning of a potential radio link failure or handover failure to occur. In S1403, the method comprises: receiving, from the network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell. In S1405, the method comprises: performing a re-establishment with the at least one neighbour cell according to the configuration. It should be understood that, in some examples, one or more additional method steps are included in the method flow of FIG. 14 and are performed by the apparatus. In some examples, one or more of the method steps of FIG. 14 detailed above may not be performed, or may be performed in a different order. FIG. 15 shows an example method flow performed by an apparatus. The apparatus may be a network entity. For example, the network entity may be a base station (e.g., gNB). In some examples, the apparatus is an gNB that provides a cell that serves a communication device. In S1501, the method comprises: obtaining information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment. In S1503, the method comprises: receiving, from the communication device, an indication of a warning of a potential radio link failure or handover failure to occur for the communication device. In S1505, the method comprises: based on the indication received from the communication device, providing, to the at least one neighbour cell, an indication of contention free random access resources associated with the least one neighbour cell for the communication device. In S1507, the method comprises: providing, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources for contention-free random access associated with the at least one neighbour cell. It should be understood that, in some examples, one or more additional method steps are included in the method flow of FIG. 15 and are performed by the apparatus. In some examples, one or more of the method steps of FIG. 15 detailed above may not be performed, or may be performed in a different order. FIG. 16 shows a schematic representation of non-volatile memory media 1600a (e.g. Blu-ray disc (BD), computer disc (CD) or digital versatile disc (DVD)) and 1600b (e.g. flash memory, solid state memory, universal serial bus (USB) memory stick) storing instructions and / or parameters 1602 which when executed by a processor allow the processor to perform one or more of the steps of the methods of FIGS. 12 to 15. It is noted that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention. The examples may thus vary within the scope of the attached claims. In general, some embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although embodiments are not limited thereto. While various embodiments may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as nonlimiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. The examples may be implemented by computer software stored in a memory and executable by at least one data processor of the involved entities or by hardware, or by a combination of software and hardware. Further in this regard it should be noted that any procedures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The term “non-transitory”, as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. RAM vs ROM). As used herein, “at least one of the following: ” and “at least one of: ” and similar wording, where the list of two or more elements are joined by “and”, or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all of the elements. The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), gate level circuits and processors based on multi core processor architecture, as non-limiting examples. As used herein, the terms “means for”, “means for performing operations including”, “means configured to perform operations including”, or “means configured to perform” (or similar) may be any means that are suitable for performing the feature(s). The “means” may be configured to perform one or more of the functions and / or method steps previously described. For example, the “means” may include one or more of: at least one processor, at least one memory, transceiver circuitry, antenna circuitry, etc. It should be understood that these are provided as non-limiting examples. Alternatively, or additionally some examples may be implemented using circuitry. The circuitry may be configured to perform one or more of the functions and / or method steps previously described. That circuitry may be provided in the base station and / or in the communications device. As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analogue and / or digital circuitry); (b) combinations of hardware circuits and software, such as: (i) a combination of analogue and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as the communications device or base station to perform the various functions previously described; and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to uses of the term “means” in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying 5 software and / or firmware. The term circuitry also covers, for example integrated device. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device. The foregoing description has provided by way of exemplary and non-limiting 10 examples a full and informative description of some embodiments. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings will still fall within the scope as defined in the appended claims.

Claims

1. A communication device comprising:means for providing, to a network entity, an indication of a warning of a potential radio link failure or handover failure to occur;means for receiving, from the network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; andmeans for performing a re-establishment with the at least one neighbour cell according to the configuration.

2. The communication device according to claim 1, wherein the configuration indicates at least one of the following:a pool of resources for contention-free random access, wherein the pool of resources is common for a plurality of neighbour cells;a pool of resources that comprises at least one contention-free random access preamble, wherein the pool of resources is common for a plurality of neighbour cells;resources for contention-free random access associated with each of a plurality of neighbour cells; orat least one contention-free random access preamble associated with each of a plurality of neighbour cells.

3. The communication device according to claim 2, further comprising: means for selecting a neighbour cell from the plurality of neighbour cells, wherein the means for performing the re-establishment are for: performing the re-establishment with the neighbour cell that has been selected.

4. The communication device according to any of claims 1 to 3 wherein the configuration is received within one of the following: a radio resource control message, or a medium access control control element.

5. The communication device according to any of claims 1 to 4, wherein the reestablishment is performed based on a determination that a radio link failure or handover failure has occurred at the communication device.

6. The communication device according to any of claims 1 to 5, further comprising:means for determining that the potential radio link failure or handover failure is to occur for the communication device, wherein the determining is based on at least one of the following: an identity of a source cell associated with the communication device and an identity of a target cell ID for the communication device to handover to; a time series of downlink radio measurements performed by the communication device; L3 measurements performed at the cell level; L1 beam measurements; a sequence of serving cells or beams for the communication device; a number of cell or beam switches for the communication device; a time series associated with a location of the communication device over time; a class for velocity associated with the communication device; a timing advance associated with the communication device; a maximum number of possible retransmissions for radio link control minus a re-transmission count for radio link control; or a time series of age of medium access control protocol data units at the time when they were successfully transmitted,wherein the indication is provided when the communication device has determined that the potential radio link failure or handover failure is to occur.

7. The communication device according to any of claims 1 to 6, further comprising: means for, when it is determined that the potential radio link failure or handover failure is to occur for the communication device, determining that the at least one neighbour cell is a candidate for re-establishment for the communication device, wherein the determining is based on at least one of the following: an identity of a source cell associated with the communication device and an identity of a target cell ID for the communication device to handover to; a time series of downlink radio measurements performed by the communication device; L3 measurements performed at the cell level; L1 beam measurements; a sequence of serving cells or beams for the communication device; a number of cell or beam switches for the communication device; a time series associated with a location of the communication device over time; a class for velocity associated with the communication device; a timing advance associated with the communication device; a maximum number of possible retransmissions for radio link control minus a re-transmission count for radio link control; or a time series of age of medium access control protocol data units at the time when they were successfully transmitted,wherein information related to the at least one neighbour cell being determined as a candidate for re-establishment is provided to the network entity with the indication.

8. A network entity comprising:means for obtaining information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment;means for receiving, from the communication device, an indication of a warning of a potential radio link failure or handover failure to occur for the communication device;means for, based on the indication received from the communication device, providing, to the at least one neighbour cell, an indication of contention free random access resources associated with the least one neighbour cell for the communication device; andmeans for providing, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources for contention-free random access associated with the at least one neighbour cell.

9. The network entity according to claim 8, further comprising:means for selecting a preamble for contention-free random access associated with the at least one neighbour cell for the communication device, wherein the selecting is based on the information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment,wherein the indication of resources for contention free random access associated with the least one neighbour cell provided to the at least one neighbour cell comprises the preamble that has been selected.

10. The network entity according to claim 8 or claim 9, wherein the means for obtaining are for one of:communicating with the at least one neighbour cell to determine the resources associated with the at least one neighbour cell that are available for a re-establishment;receiving, from the at least one neighbour cell, an indication of the resources associated with the at least one neighbour cell that are available for a re-establishment; orproviding, to the at least one neighbour cell, a request for resources for contention-free random access for re-establishment; and receiving, from the at least one neighbour cell, an indication of resources for contention-free random access associated with the at least one neighbour cell that are available for a re-establishment.

11. The network entity according to any of claims 8 to 10, wherein the configuration indicates at least one of the following:a pool of resources for contention-free random access, wherein the pool of resources is common for a plurality of neighbour cells;a pool of resources that comprises at least one contention-free random access channel preamble, wherein the pool of resources is common for a plurality of neighbour cells;resources for contention-free random access associated with each of a plurality of neighbour cells; orat least one contention-free random access channel preamble associated with each of a plurality of neighbour cells.

12. The network entity according to any of claims 8 to 11, wherein the configuration is provided to the communication device within one of the following: a radio resource control message, a medium access control control element.

13. The network entity according to any of claims 8 to 12, further comprising:means for, when a potential radio link failure or handover failure is to occur for the communication device, selecting a contention free random access preamble associated with the least one neighbour cell, wherein the selecting is based on the information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment;wherein the resources associated with the at least one neighbour cell indicated in the configuration comprises the contention free random access preamble associated with the least one neighbour cell that has been selected by the network entity.

14. The network entity according to any of claims 8 to 13, further comprising:means for receiving, from the at least one neighbour cell, a notification that at least one contention-free random access channel preamble associated with the least one neighbour cell has been released.

15. A method performed by a communication device, the method comprising:providing, to a network entity, an indication of a warning of a potential radio link failure or handover failure to occur;receiving, from the network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; andperforming a re-establishment with the at least one neighbour cell according to the configuration.

16. The method according to claim 15, further comprising:selecting a neighbour cell from the plurality of neighbour cells, wherein the performing the re-establishment comprises:performing the re-establishment with the neighbour cell that has been selected.

17. The method according to claim 15 or claim 16, further comprising:determining that the potential radio link failure or handover failure is to occur for the communication device, wherein the determining is based on at least one of the following: an identity of a source cell associated with the communication device and an identity of a target cell ID for the communication device to handover to; a time series of downlink radio measurements performed by the communication device; L3 measurements performed at the cell level; L1 beam measurements; a sequence of serving cells or beams for the communication device; a number of cell or beam switches for the communication device; a time series associated with a location of the communication device over time; a class for velocity associated with the communication device; a timing advance associated with the communication device; a maximum number of possible retransmissions for radio link control minus a re-transmission count for radio link control; or a time series of age of medium access control protocol data units at the time when they were successfully transmitted, wherein the indication is provided when the communication device has determined that the potential radio link failure or handover failure is to occur.

18. The method according to any of claims 15 to 17, further comprising:when it is determined that the potential radio link failure or handover failure is to occur for the communication device, determining that the at least one neighbour cell is a candidate for re-establishment for the communication device, wherein the determining is based on at least one of the following: an identity of a source cell associated with the communication device and an identity of a target cell ID for the communication device to handover to; a time series of downlink radio measurements performed by the communication device; L3 measurements performed at the cell level; L1 beam measurements; a sequence of serving cells or beams for the communication device; a number of cell or beam switches for the communication device; a time series associated with a location of the communication device over time; a class for velocity associated with the communication device; a timing advance associated with the communication device; a maximum number of possible retransmissions for radio link control minus a re-transmission count for radio link control; or a time series of age of medium access control protocol data units at the time when they were successfully transmitted,wherein information related to the at least one neighbour cell being determined as a candidate for re-establishment is provided to the network entity with the indication.

19. A method performed by a network entity, the method comprising:obtaining information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment;receiving, from the communication device, an indication of a warning of a potential radio link failure or handover failure to occur for the communication device;based on the indication received from the communication device, providing, to the at least one neighbour cell, an indication of contention free random access resources associated with the least one neighbour cell for the communication device; andproviding, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources for contention-free random access associated with the at least one neighbour cell.

20. The method according to claim 19, further comprising:selecting a preamble for contention-free random access associated with the at least one neighbour cell for the communication device, wherein the selecting is based on the information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment,wherein the indication of resources for contention free random access associated with the least one neighbour cell provided to the at least one neighbour cell comprises the preamble that has been selected.

21. The method according to claim 19 or claim 20, wherein the obtaining comprises one of:communicating with the at least one neighbour cell to determine the resources associated with the at least one neighbour cell that are available for a re-establishment;receiving, from the at least one neighbour cell, an indication of the resources associated with the at least one neighbour cell that are available for a re-establishment; orproviding, to the at least one neighbour cell, a request for resources for contention-free random access for re-establishment; and receiving, from the at least one neighbour cell, an indication of resources for contention-free random access associated with the at least one neighbour cell that are available for a re-establishment.

22. The method according to any of claims 19 to 21, further comprising:when a potential radio link failure or handover failure is to occur for the communication device, selecting a contention free random access preamble associated with the least one neighbour cell, wherein the selecting is based on the information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment;wherein the resources associated with the at least one neighbour cell indicated in the configuration comprises the contention free random access preamble associated with the least one neighbour cell that has been selected by the network entity.

23. The method according to any of claims 19 to 22, further comprising:receiving, from the at least one neighbour cell, a notification that at least one contention-free random access channel preamble associated with the least one neighbour cell has been released.

24. A computer program comprising instructions, which when executed by an apparatus, cause the apparatus to perform at least the following:providing, to a network entity, an indication of a warning of a potential radio link failure or handover failure to occur;receiving, from the network entity, a configuration for contention-free random access for re-establishment, wherein the configuration indicates resources for contention-free random access associated with at least one neighbour cell; andperforming a re-establishment with the at least one neighbour cell according to the configuration.

25. A computer program comprising instructions, which when executed by an apparatus, cause the apparatus to perform at least the following:obtaining information related to resources for contention-free random access associated with at least one neighbour cell that are available for a re-establishment;receiving, from the communication device, an indication of a warning of a potential radio link failure or handover failure to occur for the communication device;based on the indication received from the communication device, providing, to the at least one neighbour cell, an indication of contention free random access resources associated with the least one neighbour cell for the communication device; andproviding, to a communication device, a configuration for contention-free random access for re-establishment, wherein the configuration indicates the resources for contention-free random access associated with the at least one neighbour cell.47

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