Mitigating handover congestion in network

Abstract

Aspects and embodiments relate to an apparatus configured to delay execution of an action based on an execution delay and a method of delaying execution of an action. In particular, example embodiments provide apparatus and methods to delay performance of mobility-related events (e.g., handover). One aspect provides an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the device to at least: obtain an indication of an execution delay to be applied by the device relating to an action to be performed by the device, the execution delay based on one or more operational characteristics of the device; determining that the action is to be performed by the device; and delaying execution of the action based on the execution delay. Arrangements and implementations provide a mechanism to mitigate RACH load congestion. The arrangement provides a mechanism to distribute handover execution loads across limited or limited periods of time (e.g., in the form of RACH attempts initiated by UEs).

Description

Technical Field

[0001] Various example embodiments relate to apparatus configured to delay execution of an action based on an execution delay and methods of delaying execution of an action. In particular, example embodiments provide apparatus and methods of delaying execution of a mobility-related event (eg, handover). Background Art

[0002] The 3GPP standards include support for the use of non-terrestrial network (NTN) nodes, including low earth orbit (LEO), GEO satellites, unmanned aerial systems (UAS), high altitude platform systems (HAPS) devices, etc., to provide, for example, 5G New Radio (NR) services to users on Earth. In other words, the 5G NR standards recognize that non-terrestrial devices (including devices located on aircraft or other flying objects located above the Earth) can form part of a radio access network, provide coverage and support communications within that radio access network.

[0003] The 5G NR standard recognizes that the NTN can be used to support communications with various types of devices within the wireless communication network, including: personal user equipment, as well as narrowband Internet of Things (NB-IoT) devices and enhanced machine type communication (eMTC) devices, all of which fall under the general term "user equipment" (UE).

[0004] Various challenges arise from using NTN equipment as RAN nodes in wireless communication systems, including some challenges with supporting mobility in a network that includes NTN functionality. Summary of the invention

[0005] The scope of protection sought by various exemplary embodiments of the invention is set out in the independent claims.Example embodiments and features described in this specification that do not fall within the scope of the independent claims, if any, should be interpreted as examples that aid in understanding the various embodiments of the invention.

[0006] According to various but not necessarily all example embodiments, there is provided an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: obtain an indication of an execution delay to be applied by the apparatus in relation to an action to be performed by the apparatus, the execution delay being based on one or more operating characteristics of the apparatus; determine that an action is to be performed by the apparatus; and delay performance of the action based on the execution delay.

[0007] According to some embodiments, execution of the action is delayed until the execution delay has elapsed.

[0008] According to some embodiments, the actions to be performed by the apparatus include transmission of a random access channel preamble.

[0009] According to some embodiments, the action to be performed by the apparatus is associated with a mobility event, the action comprising: handover or conditional handover.

[0010] According to some embodiments, the action to be performed by the apparatus is associated with: a reconfiguration of the apparatus based on the obtained radio resource control reconfiguration message, and optionally wherein the reconfiguration message comprises a handover or conditional handover command.

[0011] According to some embodiments, the action to be performed by the apparatus is associated with a mobility event, according to which the apparatus is configured to obtain a resource grant by monitoring a received signal.

[0012] According to some embodiments, the mobility event is associated with a no random access channel mobility event and the apparatus is configured to acquire an uplink grant by monitoring a physical downlink control channel.

[0013] According to some embodiments, the mobility event is associated with a no random access channel mobility event and the apparatus has acquired a pre-configured resource grant of time or frequency resources.

[0014] According to some embodiments the apparatus is caused to obtain an indication of a time limit for performing an action to be performed by the apparatus, wherein the execution delay to be applied by the apparatus is further based on the obtained indication of the time limit.

[0015] According to some embodiments, the apparatus may be caused to evaluate a time limit based on the acquired indication.

[0016] According to some embodiments, the time constraint comprises an indication of a final time by which the action must be completed.

[0017] According to some embodiments, the time constraint comprises an indication of a final time by which the action must be initiated by the device.

[0018] According to some embodiments, the operational characteristics of the device are based on the likelihood of success of an action to be performed by the device, and the greater the likelihood of success, the longer the resulting execution delay.

[0019] According to some embodiments, the operational characteristics of the device are based on the likelihood of success of an action to be performed by the device, and the greater the likelihood of success, the smaller the resulting execution delay.

[0020] In accordance with some embodiments, the likelihood of success of an action to be performed by the device is based on at least one of: radio conditions being experienced by the device, an indication of the number of other devices expected to perform the action to be performed by the device, an indication of a historical success rate of the action to be performed by the device, or an indication of a current success rate of the action to be performed by the device.

[0021] According to some embodiments, the indication is received by the device in a messaging from the network.

[0022] According to some embodiments, the messaging from the network includes broadcast or device specific messaging from the network.

[0023] According to some embodiments, the operating characteristics of the device are based on a priority of the device, and the higher the priority of the device, the smaller the execution delay obtained.

[0024] According to some embodiments, the priority of the device is based on at least one of: an indication of a quality of service associated with the device, an indication of a device priority provided to the device, or an indication of a time remaining before an action to be performed by the device must be initiated or completed.

[0025] According to some embodiments, the execution delay is further based on a characteristic of a unique identifier associated with the device.

[0026] According to some embodiments, the characteristics of the unique identifier include: at least one digit of the unique identifier.

[0027] According to some embodiments, the execution delay comprises a function of one or more operating characteristics associated with the apparatus.

[0028] According to some embodiments, the action to be performed by the apparatus is associated with a mobility event, the mobility event comprising: a handover or a conditional handover.

[0029] According to some embodiments, the action to be performed by the apparatus comprises a conditional handover between a source cell and a target cell in a non-terrestrial network.

[0030] According to some embodiments, an action to be performed by the device is triggered by one or more action triggering conditions to be evaluated by the device.

[0031] According to some embodiments, the apparatus is caused to determine that an action is to be performed by the apparatus by determining that one or more action triggering conditions are evaluated to be satisfied.

[0032] According to some embodiments, the apparatus comprises a user equipment comprising circuitry configured to generate a radio frequency signal.

[0033] According to various but not necessarily all example embodiments, a device is provided, comprising: means for obtaining an indication of an execution delay to be applied by the device in relation to an action to be performed by the device, the execution delay being based on one or more operating characteristics of the device; means for determining that an action is to be performed by the device; and means for delaying performance of the action based on the execution delay.

[0034] The components may perform optional features associated with the above-described apparatus.

[0035] According to various but not necessarily all example embodiments, a device is provided, comprising: a circuit system configured to obtain an indication of an execution delay to be applied by the device related to an action to be performed by the device, the execution delay being based on one or more operating characteristics of the device; a circuit system configured to determine that an action is to be performed by the device; and a circuit system configured to delay performance of the action based on the execution delay.

[0036] The circuit system may be configured to perform the optional features set forth in relation to the apparatus described above.

[0037] According to various but not necessarily all example embodiments, a method is provided that includes: obtaining an indication of an execution delay to be applied by the device in relation to an action to be performed by the device, the execution delay being based on one or more operating characteristics of the device; determining that an action is to be performed by the device; and delaying execution of the action until the execution delay has passed.

[0038] According to some embodiments, execution of the action is delayed until the execution delay has elapsed.

[0039] According to some embodiments, the actions performed by the apparatus include transmission of a random access channel preamble.

[0040] According to some embodiments, the action to be performed by the apparatus is associated with a mobility event, the action comprising: handover or conditional handover.

[0041] According to some embodiments, the action to be performed by the apparatus is associated with: apparatus reconfiguration based on the obtained radio resource control reconfiguration message, and optionally wherein the reconfiguration message comprises a handover or conditional handover command.

[0042] According to some embodiments, the action to be performed by the apparatus is associated with a mobility event, according to which the apparatus is configured to obtain a resource grant by monitoring a received signal.

[0043] According to some embodiments, the mobility event is associated with a no random access channel mobility event and the apparatus is configured to acquire an uplink grant by monitoring a physical downlink control channel.

[0044] According to some embodiments, the mobility event is associated with a no random access channel mobility event and the apparatus has acquired a pre-configured resource grant of time or frequency resources.

[0045] According to some embodiments the method comprises obtaining an indication of a time limit for performing an action to be performed by the apparatus, wherein an execution delay to be applied by the apparatus is further based on the obtained indication of the time limit.

[0046] According to some embodiments, the time constraint comprises an indication of a final time by which the action must be completed.

[0047] According to some embodiments, the time constraint comprises an indication of a final time by which the action must be initiated by the device.

[0048] According to some embodiments, the operational characteristics of the device are based on the likelihood of success of an action to be performed by the device, and the greater the likelihood of success, the longer the resulting execution delay.

[0049] According to some embodiments, the operational characteristics of the device are based on the likelihood of success of an action to be performed by the device, and the greater the likelihood of success, the smaller the resulting execution delay.

[0050] In accordance with some embodiments, the likelihood of success of an action to be performed by the device is based on at least one of: radio conditions being experienced by the device, an indication of the number of other devices expected to perform the action to be performed by the device, an indication of a historical success rate of the action to be performed by the device, or an indication of a current success rate of the action to be performed by the device.

[0051] According to some embodiments, the indication is received by the device in a messaging from the network.

[0052] According to some embodiments, the operating characteristics of the device are based on a priority of the device, and the higher the priority of the device, the smaller the execution delay obtained.

[0053] According to some embodiments, the priority of the device is based on at least one of: an indication of a quality of service associated with the device, an indication of a device priority provided to the device, or an indication of a time remaining before an action to be performed by the device must be initiated or completed.

[0054] According to some embodiments, the execution delay is further based on a characteristic of a unique identifier associated with the device.

[0055] According to some embodiments, the characteristics of the unique identifier include: at least one digit of the unique identifier.

[0056] According to some embodiments, the execution delay comprises a function of one or more operating characteristics associated with the apparatus.

[0057] According to some embodiments, the action to be performed is associated with a mobility event, the mobility event comprising: a handover or a conditional handover.

[0058] According to some embodiments, the action to be performed comprises a conditional handover between a source cell and a target cell in the non-terrestrial network.

[0059] According to some embodiments, an action to be performed by the apparatus is triggered by one or more action triggering conditions to be evaluated by the apparatus.

[0060] According to some embodiments, the method comprises determining that an action is to be performed by the apparatus by determining that one or more action triggering conditions are evaluated to be satisfied.

[0061] According to some embodiments, the method is performed by a user equipment comprising circuitry configured to generate a radio frequency signal.

[0062] According to various, but not necessarily all, example embodiments, a non-transitory computer-readable medium is provided, including program instructions stored thereon for performing at least the following: obtaining an indication of an execution delay to be applied by the apparatus in relation to an action to be performed by the apparatus, the execution delay being based on one or more operating characteristics of the apparatus; determining that an action is to be performed by the apparatus; and delaying performance of the action until the execution delay has elapsed.

[0063] The instructions may be used to perform the optional features set forth in relation to the above method.

[0064] According to various but not necessarily all example embodiments, a computer program product is provided that, when executed on a computer, is operable to obtain an indication of an execution delay to be applied by the apparatus in relation to an action to be performed by the apparatus, the execution delay being based on one or more operating characteristics of the apparatus; determine that an action is to be performed by the apparatus; and delay execution of the action until the execution delay has elapsed.

[0065] The computer program product may be operable to perform the optional features set forth in relation to the method above.

[0066] According to various but not necessarily all example embodiments, an apparatus is provided, comprising: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the apparatus to at least: determine an action to be performed by a user device; and provide an indication of an execution delay associated with the action to be applied by the user device, the execution delay being based on one or more operating characteristics of the user device.

[0067] The apparatus may include a base station including circuitry configured to generate a radio frequency signal.

[0068] The base station apparatus may be configured to perform similar optional features as described above in relation to the user equipment apparatus.

[0069] According to various but not necessarily all example embodiments, an apparatus is provided that includes: a circuit system configured to determine an action to be performed by a user device; a circuit system configured to provide an indication of an execution delay associated with the action to be applied by the user device, the execution delay being based on one or more operating characteristics of the user device.

[0070] According to various but not necessarily all example embodiments, an apparatus is provided that includes: components configured to determine an action to be performed by a user device; components configured to provide an indication of an execution delay related to the action to be applied by the user device, the execution delay being based on one or more operating characteristics of the user device.

[0071] According to various but not necessarily all example embodiments, a method is provided that includes determining an action to be performed by a user device; providing an indication of an execution delay associated with the action to be applied by the user device, the execution delay being based on one or more operating characteristics of the user device.

[0072] The method performed by the base station may be configured to perform similar optional features as set out in relation to the user equipment method above.

[0073] According to various but not necessarily all example embodiments, a non-transitory computer-readable medium is provided, including program instructions stored thereon for performing at least the following items: determining an action to be performed by a user device; providing an indication of an execution delay associated with the action to be applied by the user device, the execution delay being based on one or more operating characteristics of the user device.

[0074] According to various but not necessarily all example embodiments, a computer program product is provided that, when executed on a computer, is operable to determine an action to be performed by a user device; and provide an indication of an execution delay associated with the action to be applied by the user device, the execution delay being based on one or more operating characteristics of the user device.

[0075] Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.

[0076] Where an apparatus feature is described as being operable to provide a function, it will be understood that this includes apparatus features that provide that function or that are adapted or configured to provide that function. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0078] Figure 1Some of the main components of a typical non-terrestrial network are schematically shown;

[0079] Figure 2 The basic condition switching scheme is schematically shown;

[0080] Figure 3 schematically illustrates cell overlap of a source cell and a target cell in an earth fixed cell network deployment;

[0081] Figure 4 Schematically illustrating steps that may be implemented at a user equipment according to one embodiment;

[0082] Figure 5 is a signaling diagram schematically illustrating a conditional handover scheme according to a general implementation including a HO execution timer arranged;

[0083] Figure 6 schematically illustrating some components of a wireless communication network including nodes according to some arrangements; and

[0084] Figure 7 The steps of a method performed at a node according to some arrangements are schematically illustrated. DETAILED DESCRIPTION

[0085] Before discussing example embodiments in greater detail, an overview will first be provided.

[0086] NTN has been specified as part of Release 17 of the 3GPP standard. The main deployment scenario envisioned uses low earth orbit (LEO) satellites at an altitude of 600km to 1200km in a transparent architecture to support communications between user equipment (UE) and base stations on Earth. Release 18 further enhances NTN by proposing improvements in various operating areas, including support for UE mobility.

[0087] Non-Terrestrial Network (NTN)

[0088] Figure 1 Some major components of a typical non-terrestrial network 100 are schematically shown. In the non-terrestrial network 100, communication services are provided to user equipment (UE) 110 via one or more satellites or unmanned aircraft system (UAS) platforms 120. User data from a data network 200 is routed through an NTN gateway 130 located on the ground and the satellite or UAS platform 120. Typically, the wireless link between the satellite or UAS platform 120 and the NTN gateway 130 (NTN-GW) is referred to as a "feeder link" 300, and the wireless link 400 between the satellite and each UE is referred to as a "service link".

[0089] The satellite or UAS platform 120 may include a low earth orbit (LEO) satellite that orbits the earth at an altitude between 500-1500 km. Each such LEO satellite may generally provide an NR service area 600 on the earth via one or more satellite beams that create an NR cell in its beam coverage area 600a. Due to their low altitude, such LEO satellites move at a speed of approximately 7.5 km / s relative to the earth's surface, and the NR service area 600 may be considered to be constantly scanning an area of ​​the earth's surface.

[0090] A UE 110 operating in an NTN such as that shown will have Global Navigation Satellite System (GNSS) support, meaning that the UE 110 will typically have access to what is typically considered to be GNSS position and / or GNSS time. Providing support for GNSS is a requirement for the UE to acquire an understanding of the time and frequency relationship between itself and any satellites forming part of the NTN Radio Access Network (RAN) in order to synchronize and maintain synchronization.

[0091] The described arrangements generally relate to methods applicable to supporting conditional handover (CHO) in connection with non-terrestrial networks (NTNs).More particularly, the described arrangements relate to methods applicable to supporting CHO for earth fixed cells.

[0092] Earth Fixed Cell (EFC)

[0093] An Earth-fixed cell is a cell of radio coverage that is projected onto the Earth via a satellite beam that is adjusted so that the cell does not move with the movement of the satellite. In other words, the satellite or UAS platform is configured so that it continuously adjusts the direction of the beam to compensate for the movement of the satellite relative to the Earth (7.5 km / s).

[0094] Even with such continuous beam adjustments, at some point the satellite providing the EFC may be positioned relative to the EFC such that it cannot effectively serve that EFC, or other deployment or configuration aspects may cause the satellite to cease serving an area. In this case, a new satellite may be configured to provide a radio coverage beam that effectively "takes over" the EFC and serves the area of ​​that EFC. In this case, the UEs in the EFC may need to switch to the new cell. In the event of such a switch, a large number of UEs in the EFC will need to perform a switch to the "new" beam serving the EFC. The switching of multiple UEs may need to occur within a limited period of time, which may produce an expected peak in switching-related messaging and processing.

[0095] Conditional Handover (CHO) has been defined as part of 3GPP Release 16. The purpose of CHO is to increase handover robustness by decoupling the HO preparation and HO execution phases.

[0096] CHO is a mechanism that can help efficient handover of UEs operating in EFC. CHO was identified in Release 17 of the 3GPP standard to help support NTN operations, and some NTN-specific enhancements are provided.

[0097] Figure 2 The basic conditional switching scheme is schematically shown. In particular, Figure 2 It is a signaling diagram indicating the signaling steps that occur between various nodes in a standard network as part of a conditional handover scheme. These nodes include: user equipment 110; source node 700a; target node 700b; other potential target nodes 700c; serving gateway, user plane function or equivalent 800; and mobility management entity or access and mobility management function entity or equivalent 900.

[0098] Figure 2 A CHO scheme is shown, where steps P1 to P9 are similar to the baseline HO (BHO) set in New Radio (NR) Release 15 standardized by 3GPP.

[0099] At step P1 : a configured event triggers UE 110 to send a measurement report.

[0100] At step P2: Based on the UE measurement report, the source node 100a is configured to take CHO action.

[0101] At steps P3 and P4: the source node communicates with one or more target nodes 700b, 700c to prepare one or more target cells for handover by sending a CHO request.

[0102] At steps P5 and P6: the target nodes 700b and 700c perform admission control on the CHO request from the source node 700a.

[0103] At steps P7 and P8: Assuming that the admission control at the potential target nodes 700b and 700c is successful, the potential target nodes 700b and 700c notify the source node 700a that the CHO request has been confirmed.

[0104] At step P9 : the source node is configured to send an RRC reconfiguration (handover command) to the UE 110 .

[0105] With respect to the basic handover (BHO) set forth in NR Release 15, the UE 110 will immediately access the target cell to complete the handover. With respect to the conditional handover (CHO), the UE 110 is configured so that once the additional CHO execution conditions are met, it will only take steps to access the target cell. In other words, the HO preparation and execution phases are decoupled. The additional CHO conditions are typically configured to the UE as part of the HO command, for example, by the source node 700a. The advantage of CHO is that the HO command can be sent before a HO event that may be required, for example, when the radio link between the source cell supported by the source node 700a and the UE is strong enough, without the risk of the UE attempting to access the network via the target cell, and may cause problems associated with the UE to network connection using the source cell or the target cell. That is, the CHO process can provide mobility robustness within the network.

[0106] In standard HO schemes such as those described above, handover and conditional handover measurement trigger conditions are typically linked to radio conditions experienced and measured at the UE. For example, the trigger condition may include a threshold reference signal received power (RSRP) difference at the UE between the source cell and the target cell.

[0107] In Release 17 NTN, the CHO scheme has been enhanced so that it is linked to (radio) conditions experienced at the UE as previously described (such as measurement events A3, A4 or A5 (defined in RRC)), and is also linked to a time condition requiring the triggering measurement event to occur within a time window (e.g., measurement events A3, A4, A5 satisfied within the time window [t1, t2]). In other words, with respect to NTN CHO, it is possible to provide a joint configuration related to location and RSRP as well as time and RSRP. Such a condition recognizes that the received power level alone may not be sufficient in NTN for the UE to make a decision as to whether it is appropriate to trigger a mobility event. This may occur in particular because in NTN EFC, the RSRP at the cell edge (typically the area associated with handover) may not be very different from the RSRP measured at the cell center.

[0108] Figure 2 Also included are the relevant signaling steps in the CHO process.

[0109] At step P10: UE 110 is configured to evaluate the CHO condition set in the RRC reconfiguration of step P9.

[0110] At step P11 : In case of a CHO event in the NTN, the NTN UE 110 may have CHO conditions, which may include location / time and radio measurement condition(s).

[0111] The time-based CHO execution condition is specified as "CondEvent T1" in the 3GPP technical standard.

[0112] The 3GPP technical standards state that:

[0113] CondEvent T1 (time measured at UE is within duration from threshold)

[0114] The UE shall:

[0115] 1> When condition T1-1 is met, the entry condition of the event is considered to be met, as described below;

[0116] 1> When condition T1-2 is met, consider satisfying the exit condition of the event, as described below;

[0117] Inequality T1-1 (entry condition)

[0118] Mt>Thresh1,

[0119] Inequality T1-2 (leave condition)

[0120] Mt>Thresh1+Duration.

[0121] The variables in the formula are defined as follows:

[0122] Mt is the time measured at the UE,

[0123] Thresh1 is the threshold parameter for this event (i.e., t1-Threshold as defined in reportConfigNR for this event),

[0124] Duration is the duration parameter of this event (ie, the duration defined in reportConfigNR of this event).

[0125] Mt is expressed in ms.

[0126] Thresh1 is expressed in the same units as Mt.

[0127] Duration is expressed in the same units as Mt.

[0128] A typical use of time-based CHO with the [t1, t2] condition is related to NTN EFC. In EFC, it is assumed that there is an overlap in time where both the source cell and the target cell are available at the same area on the earth: they create the same cell area. Typically, the values ​​of t1 and t2 will be set to the start and end of the time overlap window, that is, t1 is set to the time when the target cell becomes available, and t2 to the time when the source cell "disappears". However, the time window can be set so that there is a short overlap for handover within the total time overlap window, or can be set so that there is no overlap. In addition, t2 can be set to be greater than t-service. In general, t1 and t2 may not necessarily be related to the coverage overlap between the source cell and the target cell. t1 and t2 may, for example, relate to timing in coverage that is only related to the target cell. Therefore, a time window can be set separately for each handover or conditional handover candidate cell.

[0129] Figure 3 The figure schematically shows the cell overlap of the source cell and the target cell in the earth fixed cell network deployment. Figure 3 As shown, the source cell of the earth-fixed cell 1000 is provided by the satellite 700a, and the target cell of the earth-fixed cell 1000 is provided by the satellite 700b.

[0130] If the enhanced CHO condition is applied, the UE may be configured to check the radio conditions experienced at the UE from the source cell and the target cell in the time window between t1 and t2, and perform a handover if a handover condition related to the radio conditions is met within the time window. It should be understood that during time t1-t2, two cells are available at the same cell area, and if these cells use the same frequency, they will interfere with each other, so some interference coordination may be required, but addressing this issue is outside the scope of CHO considerations in the context of the described arrangement.

[0131] If it is determined that the CHO condition is met at the UE, then Figure 2 Further steps are described to enable the handover to occur successfully.

[0132] At step P12: after having determined that the CHO condition is satisfied, the UE 110 is configured to transmit a physical random access channel (PRACH) preamble to the target node 700b for which the CHO condition is determined to be satisfied (this is true in both the case of contention-free random access and contention-based random access).

[0133] At step P13: the target node 700b is configured to respond to the UE PRACH preamble with a PRACH response.

[0134] At step P14: the UE is configured to confirm to the target node 700b that the RRC reconfiguration required at the UE has been completed.

[0135] At step P15: the target node 700b is configured to notify the source node 700a that the handover has been successfully completed.

[0136] At step P16: after receiving the handover success messaging from the target node 700b, the source node 700a is configured to stop transmitting to and receiving from the UE 110 and start data forwarding in order to ensure that no packets are lost as part of the handover.

[0137] At step P17: the service node state is transferred to the target node 700b.

[0138] At step P18: the previous source node 700a continues forwarding data to the new source node 700b.

[0139] At step P19: the original source node 700a releases the CHO preparation completed at the other potential target node 700c.

[0140] At step P20: all network-side entities (700a, 700b, 700c, 800 and 900) perform path switching so that the UE 110 is attached to the new source node 700b.

[0141] The implementation of CHO in relation to the NTN EFC may result in a large number of UEs performing handovers almost simultaneously. As a result, handover congestion may occur in the network. In order to alleviate this congestion, in particular on the PRACH requests sent by the UE to the target node, one possibility is to randomly spread the RACH initiation times at the UE to distribute the handover load. The described arrangement recognizes that a simple random spread of the RACH initiation times may still result in significant handover congestion.

[0142] The described arrangements seek to address situations where a large number of UEs may typically be triggered to perform actions substantially simultaneously, resulting in significant conflict inefficiencies within the network. The described arrangements seek to alleviate handover congestion, for example, by taking steps to more intelligently distribute handover initiations of a large number of UEs within a limited time period. In particular, some implementations provide network configuration mechanisms for distributing actions (e.g., several UE handovers) across a limited time window. The arrangements and implementations described in more detail below seek to diffuse expected peaks in signaling or messaging load within the network.

[0143] The specification of condEvent T1 does not include provisions to prevent a large number of UEs from being configured with the same T1-T2, and therefore, it allows the time-based CHO execution conditions for a large number of UEs to be satisfied substantially at the same time. For example, if a large number of UEs in a serving cell initiate random accesses at almost the same time, it is likely that such a large number of requests will result in a poor random access success rate, in other words, RACH load congestion.

[0144] The arrangement and implementation provide a mechanism to alleviate RACH load congestion. The arrangement provides a mechanism to distribute the handover execution load (e.g. in the form of RACH attempts initiated by the UE) across a restricted or limited time period. For example, in the case of a handover in EFC, the time period may include the time period between the target cell becoming available and the source cell becoming unavailable (T1-T2) or the time period between the time the target cell is available and t-Service (when the serving cell is no longer available). In some implementations, the distribution of handover execution may be achieved via network control of UE handover execution requests across a known time period.

[0145] Methods that rely on completely random selection of delays are suboptimal. For example, a random distribution may still result in high load and may cause handover failures. Randomness may also not ensure uniform distribution in time. The method according to the described arrangement recognizes that it may be beneficial to allow some network control, supporting a distribution in which appropriate UEs have a higher likelihood of success. For example, by assigning a short execution delay to high priority UEs, they may be able to attempt to connect twice in a limited window, assuming the first attempt is unsuccessful. Similarly, the method according to the described arrangement can prioritize user equipment that is determined to be operating under good radio conditions.

[0146] Methods that rely solely on random distribution lack the possibility to apply a certain degree of intelligent UE-specific shifting. Although a unique shift for each UE calculated by the network will involve a large signaling overhead, the method recognizes that implementing a delay corresponding to one or more operating characteristics of the UE (e.g., type or priority of supported services, etc.) can provide a distribution of actions across the time window. In some arrangements, the delay distribution based on the operating characteristics of the UE can be further distributed by using another parameter (e.g., another operating characteristic) or other characteristics of the UE (e.g., UEID).

[0147] Figure 4 The steps that can be implemented at a user equipment according to one implementation manner are schematically shown.

[0148] according to Figure 4In the implementation schematically shown in the figure, as part of the received RRC reconfiguration message, the UE may receive a configuration including a CHO execution condition and a HO execution timer configuration or one or more HO execution timer settings. The HO execution timer configuration or setting may include a network-controlled UE-assisted "timer" with a configurable duration. The duration may be configured to depend on one or more parameters. The one or more parameters may include one or more operating characteristics of the user equipment or associated with the user equipment. Examples of such parameters include, for example, the remaining time until t-service, the required UE quality of service (QoS), UE priority, one or more radio condition measurements, the load of the target cell, the expected number of UEs to be switched based on the number of UEs in the serving cell, the history of random access success rate, the current random access success rate, etc.

[0149] According to one implementation, until CHO is triggered, the UE may be operable as described in relation to Figure 2 According to the arrangement implementing the HO execution timer, when the UE meets the CHO requirements (e.g., T1, T2 and other (multiple) radio conditions trigger) instead of immediately performing handover, standard transmission and reception operations at the UE to and from the source cell continue.

[0150] like Figure 4 As shown, the UE may be configured to perform the following steps.

[0151] At S1 : The UE may be configured to monitor time-based parameters related to CHO.

[0152] At S2: If the time-based parameters are met, the UE may evaluate whether CHO conditions are met, eg conditions related to radio conditions.

[0153] According to the described arrangement, when the CHO conditions are met, instead of immediately performing HO, the UE is configured to implement a delay in execution. The delay in execution in the described implementation may be indicated to the UE via a HO execution timer configuration or setting received from the network. In this implementation, when the UE determines that the condition(s) for performing a handover are met, the UE starts a UE-assisted "timer" with a configurable duration. The UE uses the timer to ensure that a delay occurs before performing a handover.

[0154] At S3: Based on the (multiple) HO execution timer conditions set by the network or pre-configured to the UE, the UE evaluates the waiting duration and starts the timer. In practice, the implementation is such that each UE waits for a certain UE-specific time before initiating HO. At step S3, the UE is still configured to continue the transmission and reception operations to and from the source cell.

[0155] At S4: The UE is configured to determine whether the evaluated wait duration has elapsed.

[0156] At S5: When the UE determines that the waiting duration has elapsed, the UE is configured to then perform or initiate HO. In other words, the UE initiates random access to the target cell (e.g., by sending a PRACH request) and, if successful, stops transmission and reception to / from the source cell.

[0157] It will be appreciated that according to various arrangements and implementations, the network may control whether HO wait is implemented by the UE, and if so, what settings are used, via a configurable execution delay set or configured by the network.

[0158] Figure 5 is a signalling diagram schematically illustrating a conditional handover scheme according to a general implementation including an execution delay in the form of a HO execution timer arranged.

[0159] Figure 5 is a signalling diagram indicating the signalling steps taking place between various nodes in a standard network as part of a handover scenario according to the described arrangement. The nodes include: user equipment 110; source node 700a and target node 700b.

[0160] At step C1: UE 110 is triggered to perform a measurement event.

[0161] At step C2: the measurement event triggers UE 110 to send a measurement report.

[0162] At step C3: Based on the UE measurement report, the source node 700a is configured to take HO actions.

[0163] At step C4: the source node communicates with the target node 700b to prepare the target cell for handover by sending a CHO request.

[0164] At step C5: the target node 700b performs admission control related to the HO request from the source node 700a.

[0165] At step C6: Assuming that the admission control at the target node 700b is successful, the target node 700b notifies the source node 700a that the HO request has been confirmed.

[0166] At step C7: the source node is configured to send an RRC reconfiguration (handover command) to the UE 110. According to the described arrangement, the RRC reconfiguration messaging includes an indication of the handover timer configuration to be implemented by the UE 110 (or a separate message sending the indication).

[0167] At step C8: the UE continues to operate, communicating with the source node 700a, while monitoring and evaluating radio conditions and, for example, other parameters (including time parameters) to determine whether the HO conditions set in the RRC reconfiguration at step C7 have been met.

[0168] At step C9: If the UE 110 determines that the handover conditions have been met, and according to the arrangement, instead of immediately initiating a handover request by sending a PRACH preamble code to the target cell 700b, or immediately starting to use pre-allocated resources (in the case of RACH-free handover), the UE is configured to initiate a timer according to the handover timer configuration received at step C7.

[0169] At step C10: once the handover timer has expired, the UE 110 is configured to start fully performing the handover by stopping transmission and reception with the source cell 700a.

[0170] At step C11 : UE 110 is configured to send a PRACH preamble to the target cell 700 b .

[0171] At step C12: the target cell 700b responds to the preamble from the UE by sending a PRACH response.

[0172] At step C13: the UE indicates to the target cell 700b that the RRC reconfiguration is complete.

[0173] At step C14: the target cell indicates to the source cell 700a that the handover has been successful.

[0174] At step C15: the source cell is configured to stop sending to and receiving from the UE, and start data forwarding.

[0175] Having provided a general overview of embodiments according to the arrangement, more details are provided below regarding the configuration of a handover execution timer, or generally how an execution delay is determined.

[0176] HO execution timer configuration

[0177] The HO execution timer according to the arrangement may be implemented in various ways.

[0178] According to one example implementation, calculation of the wait time duration may be performed as follows.

[0179] In one implementation, it is assumed that the network wants to evenly distribute the HO execution of several UEs in the remaining time between windows t1 and t2, which otherwise may perform HO substantially simultaneously. In some examples, the time window may, for example, include a time window between the current time and t-service, but it should be understood that t2 does not have to be t-service, but can be equivalent to t-service.

[0180] As part of the messaging related to the HO execution timer, the network may provide the UE with information indicating that the last number in the UE ID is to be used as at least part of the calculation of the UE-specific HO wait time duration.

[0181] For example, such a calculation could look like this:

[0182] The waiting time of UE with ID yyyyyx = x*r / 10-t-margin,

[0183] Wherein the remaining time until the end of the window allowing initiation of CHO is referred to as r. As described above, one or more other parameters may also be used as part of the waiting time calculation, or as part of the decision as to whether to implement a waiting time. As an example, the operating characteristics of the UE may be taken into account, for example, by applying a weight proportional to the required QoS or reported radio conditions.

[0184] It should be understood that the UE-specific timer may be based on various UE operational factors or parameters, including, for example, dependence on at least one of the following:

[0185] • A function that depends on the time remaining between the current time and t-Service or T2. The output of such a function may be such that it is unique for each UE, for example as described above.

[0186] • A function that depends on the time remaining between the current time and [t-service-t-margin], where t-margin is the time margin configured by the network to allow additional access attempts to the target cell if the first attempt fails (e.g. due to RACH collision).

[0187] For example, the network may set t-margin UE specifically depending on UE operating characteristics.

[0188] See also the above examples.

[0189] A function or selection that depends on the Quality of Service (QoS) or priority bearer associated with the UE. For example, the waiting time can be configured to allow high QoS users to access earlier.

[0190] (or when RACH load is low), such that RACH success is possible and / or such that the UE has enough time to retry in case of a collision. Such an example function may be based on, for example, a 5G QoS identifier. As an example, the delay function may be determined such that the delay follows a uniform distribution between x and y, where:

[0191] For high QoS UE: x = 0s, y = 1s, and

[0192] For low QoS UE: x=1s, y=4s (ie, y is greater than that of high QoS UE).

[0193] Depending on the function or selection of weighted distributed timers, the network can stagger the distribution of switching execution over time. This implementation may be useful, for example, in situations where interference coordination is performed in the resource domain, and appropriate (multiple)

[0194] Adaptation enables multiple available resources and multiple UEs to be appropriately adapted together.

[0195] • Apply a function or selection of a weighted distribution according to the actual radio condition(s) experienced by the UE.

[0196] Each of the above functions may be defined by the network and provided to the UE, or the UE may be pre-configured with such functions to evaluate the execution delay.

[0197] As described above, it may be beneficial to allow some network control to support the distribution of appropriate UEs with a higher probability of success. In an embodiment, the probability of success of the action to be performed by the UE is based on the radio conditions that the UE is experiencing. In an embodiment, the probability of success of the action to be performed by the UE is based on the number of other UEs expected to perform the action to be performed by the UE. In an embodiment, the probability of success of the action to be performed by the UE is based on an indication of the historical success rate of the action to be performed by the UE. In an embodiment, the probability of success of the action to be performed by the UE is based on an indication of the current success rate of the action to be performed by the UE. The UE can determine any of these by itself, or the UE can receive indications of these from the network. For example, the network indicates the number of other UEs expected to perform the same action at a given moment or time window.

[0198] In an embodiment, the priority of a UE may be based on a quality of service associated with the UE. In an embodiment, the priority of a UE may be based on a priority indication provided to the device from the network. In an embodiment, the priority of a UE may be based on an indication of the time remaining before an action to be performed by the UE must be initiated or completed.

[0199] Figure 6Some components of a network including nodes according to some arrangements are schematically illustrated. The network 6000 includes a plurality of network nodes 6200 , which may include network nodes in an NTN, communicating with a user equipment 6100 .

[0200] The user equipment 6100 is in the form of a device, including:

[0201] 6110: A circuit system configured to obtain an indication of an execution delay to be applied by a device related to an action to be performed by the device, the execution delay being based on one or more operating characteristics of the device; 6120: A circuit system configured to determine that an action is to be performed by the device; and 6130: A circuit system configured to delay execution of the action based on the execution delay.

[0202] The network access node 6200 is in the form of a device, including:

[0203] 6210: Circuitry configured to determine an action to be performed by a user equipment; and

[0204] 6220: Circuitry configured to provide an indication of an execution delay associated with an action to be applied by a user device, the execution delay being based on one or more operating characteristics of the user device.

[0205] Figure 7 The steps of the method performed at some network nodes according to some arrangements are schematically shown.

[0206] The user equipment 6100 may be configured to perform a method comprising the following steps: 7110: obtaining an indication of an execution delay to be applied by an apparatus in relation to an action to be performed by the apparatus, the execution delay being based on one or more operational characteristics of the apparatus;

[0207] 7120: Determining an action to be performed by the device; and

[0208] 7130: Delay execution of an action based on an execution delay.

[0209] The network access node 6200 may be configured to perform a method comprising the following steps:

[0210] 7210: Determine an action to be performed by the user equipment; and

[0211] 7220: Provide an indication of an execution delay associated with an action to be applied by a user device, the execution delay being based on one or more operating characteristics of the user device.

[0212] Although the arrangement and implementation have been described with respect to RACH-based HO delay, the above principles may be applied with respect to UEs implementing RACH-free handover and CHO. In particular, the handover delay may be implemented such that, for example, users with pre-allocated grants may be prioritized, and UEs with pre-allocated grants that occur earliest in time may be prioritized. Alternatively, in some implementations, the waiting time applied by the RACH-free UE may be made dependent on the time of the pre-allocated grant.

[0213] Having described the principles of the method and implementation in the context of implementing HO using RACH in an NTN EFC, it will be appreciated that similar principles may be applied with respect to backoff timers in RACH. The backoff timer operates to delay a UE from retrying to connect via RACH. If multiple UEs experience RACH collisions or congestion, and similar RACH backoff times are applied, they may attempt to retry RACH requests at approximately the same time and experience the same congestion again. By applying similar principles to the backoff timer, distributing such retries in time may help alleviate such congestion. It will be appreciated that the time distribution of the RACH backoff timer may be implemented in a similar manner, and the timer may be implemented according to the same aspects as described above.

[0214] Furthermore, if the action to be performed by the UE includes a mobility action between a source satellite and a target satellite supported by the same gNB (e.g., FL handover, unchanged physical cell identity (PCI) mobility), the arrangements described with respect to the application of a delay in the execution of the handover action are applicable.

[0215] Those skilled in the art will readily appreciate that the steps of various above-mentioned methods can be performed by a programmed computer. In this article, some embodiments are also intended to encompass program storage devices, such as digital data storage media, which are machine or computer readable and encode machine executable or computer executable instruction programs, wherein the instructions perform some or all of the steps of the above-mentioned method. The program storage device can be, for example, a digital memory, a magnetic storage medium such as a disk and a tape, a hard drive, or an optically readable digital data storage medium. Embodiments are also intended to encompass computers programmed to perform the steps of the above-mentioned method. As used herein, the term non-transient is a limitation of the medium itself (that is, tangible, rather than a signal), rather than a limitation to data storage persistence (e.g., RAM to ROM).

[0216] As used in this application, the term "circuitry" may refer to one or more or all of the following:

[0217] (a) hardware circuit implementation only (such as implementation in analog and / or digital circuitry only); and

[0218] (b) a combination of hardware circuitry and software such as (where applicable):

[0219] (i) A combination of analog and / or digital hardware circuits with software / firmware

[0220] (ii) any portion of hardware processor(s) (including digital signal processor(s)) with software, software and memory that work together to enable a device such as a mobile phone or server to perform various functions; and

[0221] (c) Hardware circuits and / or processor(s), such as microprocessor(s) or portions of microprocessor(s), that require software (e.g., firmware) to operate, but which may not be present when the software is not required for operation.

[0222] This definition of circuitry applies to all uses of the term in this application, including any claims. As another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to a particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cell network device, or other computing or network device.

[0223] Although example embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

[0224] Features described in the preceding description may be used in combinations other than the combinations explicitly described.

[0225] Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

[0226] Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

[0227] While an effort has been made in the foregoing description to call attention to those features of the present invention regarded as particularly important, it is to be understood that the applicant claims protection for any patentable feature or combination of features mentioned above and / or shown in the accompanying drawings whether or not specific emphasis has been placed thereon.

Claims

1. A device for communication, comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: obtaining an indication of an execution delay to be applied by the apparatus in relation to an action to be performed by the apparatus, the execution delay being based on one or more operating characteristics of the apparatus; determining that the action is to be performed by the device; as well as Execution of the action is delayed based on the execution delay. 2 . The apparatus of claim 1 , wherein the execution of the action is delayed until the execution delay has elapsed.

3. The apparatus of claim 1 or claim 2, wherein the action to be performed by the apparatus comprises: Transmission of random access channel preamble.

4. The device according to claim 1 or 2, wherein the device is caused to: An indication of a time limit for performing the action to be performed by the apparatus is obtained, wherein the execution delay to be applied by the apparatus is further based on the obtained indication of the time limit.

5. An apparatus according to claim 1 or 2, wherein the operating characteristic of the apparatus is based on a likelihood of success of the action to be performed by the apparatus, and the greater the likelihood of success, the longer the resulting execution delay.

6. An apparatus according to claim 1 or 2, wherein the operating characteristic of the apparatus is based on the likelihood of success of the action to be performed by the apparatus, and the greater the likelihood of success, the smaller the resulting execution delay.

7. An apparatus according to claim 5, wherein the likelihood of success of the action to be performed by the apparatus is based on at least one of: radio conditions being experienced by the apparatus, an indication of the number of other apparatuses expected to perform the action to be performed by the apparatus, an indication of a historical success rate of the action to be performed by the apparatus, or an indication of a current success rate of the action to be performed by the apparatus.

8. The apparatus of claim 1 or 2, wherein the operational characteristic of the apparatus is based on a priority of the apparatus, and the higher the priority of the apparatus, the smaller the resulting execution delay.

9. An apparatus according to claim 8, wherein the priority of the apparatus is based on at least one of: an indication of a quality of service associated with the apparatus, an indication of a device priority provided to the apparatus, or an indication of a time remaining before the action to be performed by the apparatus must be initiated or completed.

10. The apparatus of claim 1 or 2, wherein the execution delay is further based on a characteristic of a unique identifier associated with the apparatus.

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