Method and apparatus for handling CHO execution conditions in an NTN environment

Abstract

Embodiments of the present application relate to methods and devices for handling conditional handover (CHO) conditions in a non-terrestrial network (NTN) environment. According to an embodiment of the present application, a method may include: receiving a radio resource control (RRC) reconfiguration message, wherein the RRC reconfiguration message includes CHO configuration information associated with one or more target candidate cells and a set of CHO execution conditions associated with the one or more target candidate cells; the conditions may be based on measurement results, the distance between the UE and the base station, absolute time, timer, timing advance, elevation angle, and combinations thereof; evaluating one or more CHO execution conditions associated with each of the one or more target candidate cells; determining whether the CHO execution conditions associated with a target candidate cell are satisfied; and in response to satisfying the CHO execution conditions, performing a CHO procedure from a source cell to the target candidate cell.

Description

Technical Field

[0001] Embodiments of the present application generally relate to wireless communication technologies, and in particular, to methods and devices for handling conditions for performing conditional handover (CHO) in a non-terrestrial network (NTN) environment. Background Art

[0002] The NTN environment refers to a network or network segment that uses spacecraft or aircraft for transmission. For example, spacecraft include satellites, which can be low Earth orbit (LEO) satellites, medium Earth orbit (MEO) satellites, geostationary orbit (GEO) satellites, and highly elliptical orbit (HEO) satellites. Spacecraft include high altitude platforms (HAPs) that cover unmanned aerial systems (UASs), and the unmanned aerial systems include lighter-than-air UASs (LTA) and heavier-than-air UASs (HTA).

[0003] In the Third Generation Partnership Project (3GPP), when a user equipment (UE) needs to perform a CHO procedure from a serving cell of a source base station (BS) (e.g., a source satellite BS) to a candidate cell of a candidate BS (e.g., a target satellite BS), details on how to handle CHO execution conditions in the NTN environment have not been discussed. Summary of the Invention

[0004] Some embodiments of the present application provide a method executable by a UE. The method includes: receiving a radio resource control (RRC) reconfiguration message, where the RRC reconfiguration message includes CHO configuration information associated with one or more target candidate cells and a set of CHO execution condition parameters associated with the one or more target candidate cells; evaluating one or more CHO execution conditions associated with each of the one or more target candidate cells; determining whether the CHO execution conditions associated with a target candidate cell are satisfied; and in response to satisfying the CHO execution conditions, performing a CHO procedure from a source cell to the target candidate cell.

[0005] Some embodiments of the present application also provide a device for wireless communication. The device includes: a non-transitory computer-readable medium storing computer-executable instructions; receiving circuitry; transmitting circuitry; and a processor coupled to the non-transitory computer-readable medium, the receiving circuitry, and the transmitting circuitry, where the computer-executable instructions cause the processor to implement the above method executable by a UE.

[0006] Some embodiments of the present application provide a method that can be performed by a BS. The method includes: receiving a measurement report; and transmitting an RRC reconfiguration message, wherein the RRC reconfiguration message includes CHO configuration information associated with one or more target candidate cells and a set of CHO execution condition parameters associated with the one or more target candidate cells.

[0007] Some embodiments of the present application also provide an apparatus for wireless communication. The apparatus includes: a non-transitory computer-readable medium having computer-executable instructions stored thereon; a receiving circuit system; a transmitting circuit system; and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement the above-mentioned further method performed by the BS.

[0008] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, as well as from the specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] To describe the manner in which the advantages and features of the present application can be obtained, the description of the present application is presented by reference to specific embodiments of the application illustrated in the accompanying drawings. These drawings depict only example embodiments of the present application and therefore should not be considered as limiting the scope thereof.

[0010] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present application;

[0011] Figure 2 An exemplary flow chart illustrating an intra-AMF handover procedure according to some embodiments of the present application;

[0012] Figure 3 An exemplary flow chart illustrating a method for a CHO procedure according to some embodiments of the present application;

[0013] Figure 4 An exemplary flow chart illustrating a method for transmitting CHO execution condition parameters according to some embodiments of the present application; and

[0014] Figure 5 An exemplary block diagram illustrating an apparatus according to some embodiments of the present application. DETAILED DESCRIPTION

[0015] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present application, and is not intended to represent the only form in which the present application can be practiced. It should be understood that the same or equivalent functions can be implemented by different embodiments intended to be included in the spirit and scope of the present application.

[0016] Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings. For ease of understanding, embodiments are provided in the context of specific network architectures and new service scenarios such as 3GPP 5G, 3GPP LTE Release 8, etc. It is contemplated that as the network architecture and new service scenarios evolve, all embodiments in the present application are also applicable to similar technical problems; and furthermore, the terms cited in the present application may change, which should not affect the principles of the present application.

[0017] Figure 1 Schematic diagram illustrating a wireless communication system according to some embodiments of the present application.

[0018] As Figure 1 shown, the wireless communication system 100 includes two UEs, UE 101-A and UE 101-B, and a BS 102, e.g., a satellite BS. Although for simplicity only one BS is illustrated in Figure 1 it is contemplated that in some other embodiments of the present application, the wireless communication system 100 may include more BSs. Similarly, although for simplicity only two UEs are illustrated in Figure 1 it is contemplated that in some other embodiments of the present application, the wireless communication system 100 may include more UEs. In the coverage area of the BS 102, the UE 101-A is located at the position closest to the BS 102, that is, the distance between the position of the UE 101-A and the BS 102 is the smallest among all positions in the coverage area of the BS 102, and the UE 101-B is located at the position farthest from the BS 102.

[0019] The BS 102 may also be referred to as an access point, access terminal, base station, macro cell, Node B, evolved Node B (eNB), gNB, home Node B, relay node or device, or described using other terms used in the art. The BS 102 is typically part of a radio access network, which may include a controller communicatively coupled to the BS 102.

[0020] UE 101-A may include a computing device such as a desktop computer, laptop computer, personal digital assistant (PDA), tablet computer, smart TV (e.g., a TV connected to the Internet), set-top box, game console, security system (including security cameras), in-vehicle computer, network device (e.g., router, switch, and modem), etc. According to an embodiment of the present application, UE 101-A may include a portable wireless communication device, smartphone, cellular phone, flip phone, device with a subscriber identity module, personal computer, pager, or any other device capable of transmitting and receiving communication signals over a wireless network. In some embodiments, UE 101-A may include a wearable device such as a smartwatch, fitness band, optical head-mounted display, etc. Additionally, UE 101-A may be referred to as a subscriber unit, mobile station, mobile terminal, user, terminal, mobile terminal, wireless terminal, fixed terminal, subscriber station, user terminal, or device, or other terms used in the art to describe it.

[0021] Wireless communication system 100 is compatible with any type of network capable of transmitting and receiving wireless communication signals. For example, wireless communication system 100 is compatible with a wireless communication network, cellular phone network, time division multiple access (TDMA)-based network, code division multiple access (CDMA)-based network, orthogonal frequency division multiple access (OFDMA)-based network, LTE network, 3GPP-based network, 3GPP 5G network, satellite communication network, high-altitude platform network, and / or other communication networks.

[0022] Figure 2 Exemplary flowchart illustrating an intra-AMF handover procedure according to some embodiments of the present application. Figure 2 Embodiments depict a CHO procedure in which neither the access and mobility management function (AMF) nor the user plane function (UPF) is changed.

[0023] Reference Figure 2 , in step 200, the AMF provides mobility control information. The UE context within the source BS contains information regarding roaming and access restrictions, which is provided at connection establishment or during the last timing advance (TA) update procedure.

[0024] In step 201, the source BS transmits measurement configuration information to the UE, and the UE reports measurement results to the source BS based on the measurement configuration information. In step 202, the source BS may decide to configure a CHO configuration based on the measurement results reported by the UE.

[0025] In step 203, the source BS sends to one or more candidate target BSs (e.g., as Figure 2The target BS and other potential target BSs shown therein) transmit a Handover REQUEST message for conditional handover. For example, the Handover REQUEST message for conditional handover may carry a transparent RRC container with necessary information to prepare the CHO procedure at the target BS side.

[0026] In step 204, one or more candidate target BSs perform admission control to decide whether to allow the CHO procedure of the UE after receiving the Handover REQUEST message for conditional handover from the source BS.

[0027] In step 205, based on the admission control result, one or more candidate target BSs prepare handover resources for the UE and send a handover REQUEST ACKNOWLEDGE message containing the CHO configuration of the candidate cells to the source BS.

[0028] In step 206, the source BS sends an RRCReconfiguration message containing the CHO configuration information and CHO execution conditions of the candidate cells to the UE. In step 207, the UE sends an RRCReconfigurationComplete message to the source BS.

[0029] In step 208, after receiving the CHO configuration information, the UE maintains the connection with the source BS and starts to evaluate the CHO execution conditions of the CHO candidate cells. If the corresponding CHO execution conditions associated with at least one CHO candidate cell are met, the UE detaches from the source BS, applies the corresponding configuration information stored for this CHO candidate cell, synchronizes with this CHO candidate cell, and completes the CHO handover procedure.

[0030] In step 209, the UE sends a CHO handover complete message to one or more candidate target BSs. In step 210, further research is needed Figure 2 on the data forwarding path handover procedure among all entities in. Any ongoing data forwarding can continue.

[0031] According to some conventions in 3GPP standard documents, the execution conditions of the CHO procedure in the NTN environment may include the following:

[0032] ● Measurement-based trigger conditions: The configuration of the trigger threshold and / or which measurement events are used as trigger conditions should consider the NTN environment. For example, small changes in cell quality measured in the cell center and at the cell edge in the NTN environment.

[0033] ● Location-based triggering conditions: Additional triggering conditions based on the location of the UE and the location of the satellite can be considered in the NTN environment. The location-based CHO procedure in the LEO scenario should consider deterministic satellite movement. For example, the location-based triggering condition can be expressed as the distance between the UE and the satellite.

[0034] ● Time (timer)-based triggering conditions: This condition can be based on UTC time or be a timer-based solution. The time-based CHO procedure in the LEO scenario should consider deterministic satellite movement.

[0035] ● Timing Advance (TA) value-based triggering conditions: Additional triggering conditions based on the timing advance value to the target cell can be considered in the NTN environment.

[0036] ● Elevation Angle (EA) of source and target cells-based triggering conditions: Additional triggering conditions based on the elevation angles of the source cell and the target cell can be considered in the NTN environment.

[0037] As specified in 3GPP TS 38.331, the measurement-based triggering conditions include the following two events, namely, Event A3 and Event A5. Assuming that the source cell is the primary cell group or the secondary cell group (SpCell), 3GPP TS 38.331 defines the entry conditions and departure conditions for Event A3 and Event A5 respectively.

[0038] Event A3: The neighboring cell becomes a better offset than the SpCell.

[0039] Event A5: The SpCell becomes worse than a threshold, and the neighboring cell becomes better than another threshold.

[0040] Currently, the details of how to handle the CHO execution conditions have not been discussed in the NTN environment. Some embodiments of this application provide solutions for handling the CHO execution conditions in the NTN environment.

[0041] Figure 3 Illustrate an exemplary flowchart of a method for a CHO procedure according to some embodiments of this application. Figure 3 The embodiments can be executed by a UE (e.g., Figure 1 UE 101-A and UE 101-B as illustrated and shown in Figure 3 ). Although described with respect to a UE, it should be understood that other devices can be configured to execute a method similar to

[0042] In the exemplary method 300 as shown in Figure 3 In operation 302, the UE receives an RRC reconfiguration message. For example, the UE receives it from a BS (e.g., Figure 1The BS102) described and shown therein receives an RRC reconfiguration message. The RRC reconfiguration message includes CHO configuration information associated with one or more target candidate cells. The RRC reconfiguration message also includes a set of CHO execution condition parameters associated with one or more target candidate cells.

[0043] In operation 304, the UE evaluates one or more CHO execution conditions associated with each of the one or more target candidate cells. In operation 306, the UE determines whether the CHO execution conditions associated with the target candidate cell are met. For example, a set of CHO execution condition parameters includes a trigger timer (TTT). If the duration for which the entry condition of the CHO execution condition is met is equal to or longer than the TTT (i.e., the entry condition of the CHO execution condition is met during the TTT), then the UE determines that the CHO execution condition is met.

[0044] In operation 308, if the CHO execution conditions associated with the target candidate cell are met, then the UE performs a CHO procedure from the source cell to the target candidate cell. The source cell or the target candidate cell may be an NTN cell.

[0045] According to some embodiments, after the UE successfully accesses the target candidate cell, the UE may remove the CHO configuration information and the set of CHO execution condition parameters received in operation 302.

[0046] According to some embodiments, the UE receives a mapping table including one or more entries. Each entry of the mapping table may include at least one of the following:

[0047] - A mapping association between "distance information of the UE" and the "timing advance (TA) value between the UE and the source cell". The UE may calculate the distance information based on the UE's location information and ephemeris information; and

[0048] - A mapping association between "distance information of the UE" and the "TA value between the UE and the target candidate cell".

[0049] In some embodiments of the present application, the CHO execution conditions associated with the target candidate cell include location-based trigger conditions.

[0050] In an example, the location-based trigger condition is a location-based event, that is: the distance between the UE and the source cell is an offset greater than the distance between the UE and the target candidate cell. In short, this location-based event may be referred to as location-based event 1.

[0051] In this example, a set of CHO execution condition parameters received by the UE in operation 302 may include a distance hysteresis parameter and a distance offset. The distance offset may be associated with the "measurement object of the UE" or "satellite". The distance offset is cell-specific. For example, the distance offset is associated with the source cell of the UE.

[0052] Location-based event 1 may include an entry condition for the CHO procedure (e.g., entry condition #1 as described below), which may also be referred to as a distance entry condition or a location entry condition. In an embodiment, the entry condition is that the difference between "the distance between the UE and the source cell" (e.g., Dp as described below) and the "distance hysteresis parameter" (e.g., Hys1 as described below) is greater than the sum of "the distance between the UE and the target candidate cell" (e.g., Dn as described below) and the "distance offset" (e.g., offset1 as described below).

[0053] Location-based event 1 may include a departure condition for the CHO procedure (e.g., departure condition #1 as described below), which may also be referred to as a distance departure condition or a location departure condition. In an embodiment, the departure condition is that the sum of "the distance between the UE and the source cell" (e.g., Dp as described below) and the "distance hysteresis parameter" (e.g., Hys1 as described below) is less than the sum of "the distance between the UE and the target candidate cell" (e.g., Dn as described below) and the "distance offset" (e.g., offset1 as described below).

[0054] The entry condition and the departure condition of location-based event 1 in the above example can be represented as follows:

[0055] ● Entry condition #1: Dp - Hys1 > Dn + offset1

[0056] ● Departure condition #1: Dp + Hys1 < Dn + offset1

[0057] i. Dp (primary distance) is the distance between the UE and the source cell (e.g., SpCell).

[0058] ii. Dn (adjacent distance) is the distance between the UE and the target candidate cell (e.g., adjacent cell).

[0059] iii. offset1 is optional. offset1 can be a parameter associated with the "measurement object of the UE" or "satellite". offset1 is cell-specific.

[0060] iv. Hys1 is the hysteresis parameter of location-based event 1.

[0061] In another example, the location-based triggering condition is another location-based event, i.e., the distance between the UE and the source cell is greater than a distance threshold; and / or the distance between the UE and the target candidate cell is less than another distance threshold. Briefly, this another location-based event can be referred to as location-based event 2.

[0062] In this example, the set of CHO execution condition parameters received by the UE in operation 302 may include a distance hysteresis parameter and two distance thresholds. In different embodiments, these two distance thresholds may be the same or different.

[0063] Location-based event 2 may include two entry conditions for the CHO procedure (e.g., entry condition #1-1 and entry condition #1-2 as described below), which may also be referred to as distance entry conditions or location entry conditions. In an embodiment:

[0064] - The entry condition is that the difference between "the distance between the UE and the source cell" (e.g., Dp as described below) and the "distance hysteresis parameter" (e.g., Hys2 as described below) is greater than the distance threshold (e.g., threshold1 as described below).

[0065] - Another entry condition is that the sum of "the distance between the UE and the target candidate cell" (e.g., Dn as described below) and the "distance hysteresis parameter" (e.g., Hys2 as described below) is less than another distance threshold (e.g., threshold1' as described below).

[0066] Location-based event 2 may include two exit conditions for the CHO procedure (e.g., exit condition #1-1 and exit condition #1-2 as described below), which may also be referred to as distance exit conditions or location exit conditions. In an embodiment:

[0067] - The exit condition is that the sum of "the distance between the UE and the source cell" (e.g., Dp as described below) and the "distance hysteresis parameter" (e.g., Hys2 as described below) is less than the distance threshold (e.g., threshold1 as described below).

[0068] - Another exit condition is that the difference between "the distance between the UE and the target candidate cell" (e.g., Dn as described below) and the "distance hysteresis parameter" (e.g., Hys2 as described below) is greater than another distance threshold (e.g., threshold1' as described below).

[0069] The entry conditions and exit conditions of location-based event 2 in the above another example can be represented as follows:

[0070] ● Entry condition #1-1: Dp-Hys2 > threshold1

[0071] ● Entry condition #1-2: Dn+Hys2 < threshold1’

[0072] ● Exit condition #1-1: Dp+Hys2 < threshold1

[0073] ● Exit condition #1-2: Dn-Hys2 > threshold1’

[0074] i. Hys2 is the hysteresis parameter for location-based event 2.

[0075] Regarding the location-based triggering conditions, the UE may consider a location-based event (e.g., location-based event 1 or location-based event 2) whose entry condition is satisfied during a TTT (e.g., TTT1) as “satisfied”. The UE may consider a location-based event whose exit condition is satisfied during another TTT (e.g., TTT2) as “not satisfied”. The length of TTT1 may be the same as or different from the length of TTT2. That is, after the entry condition of a location-based event (e.g., location-based event 1 or location-based event 2) is satisfied during TTT1, the UE considers that the CHO execution condition has been “satisfied” until the exit condition of the location-based event is satisfied during TTT2. That is to say, once the exit condition of the location-based event is satisfied during TTT2, the UE considers that the CHO execution condition is “not satisfied”.

[0076] In some embodiments of the present application, the CHO execution condition associated with the target candidate cell includes a triggering condition based on timing advance (TA).

[0077] In an example, the TA-based triggering condition is a TA-based event, that is: the TA value between the UE and the source cell is an offset greater than the TA value between the UE and the target candidate cell. Briefly, this TA-based event can be referred to as TA-based event 1. For example, the UE can obtain the TA value between the UE and the source cell or the TA value between the UE and the target candidate cell from a mapping table transmitted by the BS.

[0078] In this example, a set of CHO execution condition parameters received by the UE in operation 302 may include a TA hysteresis parameter and a TA offset. The TA offset may be associated with “the measurement object of the UE” or “the satellite”. The TA offset is cell-specific. For example, the TA offset is associated with the source cell of the UE.

[0079] The TA-based event 1 may include an entry condition for the CHO procedure (e.g., entry condition #2 as described below), which may also be referred to as the TA entry condition. In an embodiment, the entry condition is that the difference between the "TA value between the UE and the source cell" (e.g., TAp as described below) and the "TA hysteresis parameter" (e.g., Hys3 as described below) is greater than the sum of the "TA value between the UE and the target candidate cell" (e.g., TAn as described below) and the "TA offset" (e.g., offset2 as described below).

[0080] The TA-based event 1 may include a departure condition for the CHO procedure (e.g., departure condition #2 as described below), which may also be referred to as the TA departure condition. In an embodiment, the departure condition is that the sum of the "TA value between the UE and the source cell" (e.g., TAp as described below) and the "TA hysteresis parameter" (e.g., Hys3 as described below) is less than the sum of the "TA value between the UE and the target candidate cell" (e.g., TAn as described below) and the "TA offset" (e.g., offset2 as described below).

[0081] The entry condition and the departure condition of the TA-based event 1 in the above example can be represented as follows:

[0082] ● Entry condition #2: TAp – Hys3 > TAn + offset2

[0083] ● Departure condition #2: TAp + Hys3 < TAn + offset2

[0084] i. TAp (primary TA) is the TA value between the UE and the source cell (e.g., SpCell).

[0085] ii. TAn (adjacent TA) is the TA value between the UE and the target candidate cell (e.g., adjacent cell).

[0086] iii. offset2 is optional. offset2 may be a parameter associated with the "measurement object of the UE" or "satellite". offset2 is specific to the cell.

[0087] iv. Hys3 is the hysteresis parameter of the TA-based event 1.

[0088] In another example, the TA-based trigger condition is another TA-based event, i.e., the TA value between the UE and the source cell is greater than a TA threshold; and / or the TA value between the UE and the target candidate cell is less than another TA threshold. Briefly, this other TA-based event may be referred to as the TA-based event 2.

[0089] For example, the UE can obtain the TA value between the UE and the source cell or the TA value between the UE and the target candidate cell from the mapping table transmitted by the BS. In this example, the set of CHO execution condition parameters received by the UE in operation 302 may include a TA hysteresis parameter and two TA thresholds. In different embodiments, these two TA thresholds may be the same or different.

[0090] The TA-based event 2 may include two entry conditions for the CHO procedure (e.g., entry condition #2-1 and entry condition #2-2 as described below), which may also be referred to as TA entry conditions. In an embodiment:

[0091] - The entry condition is that the difference between the "TA value between the UE and the source cell" (e.g., TAp as described below) and the "TA hysteresis parameter" (e.g., Hys4 as described below) is greater than the TA threshold (e.g., threshold2 as described below).

[0092] - Another entry condition is that the sum of the "TA value between the UE and the target candidate cell" (e.g., TAn as described below) and the "TA hysteresis parameter" (e.g., Hys4 as described below) is less than another TA threshold (e.g., threshold2' as described below).

[0093] The TA-based event 2 may include two exit conditions for the CHO procedure (e.g., exit condition #2-1 and exit condition #2-2 as described below), which may also be referred to as TA exit conditions. In an embodiment:

[0094] - The exit condition is that the sum of the "TA value between the UE and the source cell" (e.g., TAp as described below) and the "TA hysteresis parameter" (e.g., Hys4 as described below) is less than the TA threshold (e.g., threshold2 as described below).

[0095] - Another exit condition is that the difference between the "TA value between the UE and the target candidate cell" (e.g., TAn as described below) and the "TA hysteresis parameter" (e.g., Hys4 as described below) is greater than another distance threshold (e.g., threshold2' as described below).

[0096] The entry conditions and exit conditions of the TA-based event 2 in the above another example can be represented as follows:

[0097] ● Entry condition #2-1: TAp - Hys4 > threshold2

[0098] ● Entry condition #2-2: TAn + Hys4 < threshold2’

[0099] ● Leave condition #2 - 1: TAp + Hys4 < threshold2

[0100] ● Leave condition #2 - 2: TAn - Hys4 > threshold2’

[0101] i. Hys4 is the hysteresis parameter of event 2 based on TA.

[0102] Regarding the TA - based trigger condition, the UE may consider a TA - based event whose entry condition is satisfied during a TTT (e.g., TTT1) as "satisfied". The UE may consider a TA - based event whose leave condition is satisfied during another TTT (e.g., TTT2) as "not satisfied". The length of TTT1 may be the same as or different from the length of TTT2. That is, after the entry condition of a TA - based event (e.g., TA - based event 1 or TA - based event 2) is satisfied during TTT1, the UE considers that the CHO execution condition has been "satisfied" until the leave condition of the TA - based event is "satisfied" during TTT2. That is to say, once the leave condition of the TA - based event is satisfied during TTT2, the UE considers that the CHO execution condition is "not satisfied".

[0103] In some embodiments of the present application, the CHO execution condition associated with the target candidate cell includes an elevation angle (EA) - based trigger condition.

[0104] In an example, the EA - based trigger condition is an EA - based event, that is: the EA between the UE and the source cell is an offset greater than the EA between the UE and the target candidate cell. Briefly, this EA - based event can be referred to as EA - based event 1.

[0105] In this example, a set of CHO execution condition parameters received by the UE in operation 302 may include an EA hysteresis parameter and an EA offset. The EA offset may be associated with "UE's measurement object" or "satellite". The EA offset is cell - specific. For example, the EA offset is associated with the UE's source cell.

[0106] EA - based event 1 may include an entry condition for the CHO procedure (e.g., entry condition #3 as described below), which may also be referred to as the EA entry condition. In an embodiment, the entry condition is: the difference between "EA between the UE and the source cell" (e.g., EAp as described below) and "EA hysteresis parameter" (e.g., Hys5 as described below) is greater than the sum of "EA between the UE and the target candidate cell" (e.g., EAn as described below) and "EA offset" (e.g., offset3 as described below).

[0107] The EA-based event 1 may include a departure condition of the CHO procedure (e.g., departure condition #3 as described below), which may also be referred to as the EA departure condition. In an embodiment, the departure condition is that the sum of "the EA between the UE and the source cell" (e.g., EAp as described below) and "the TA hysteresis parameter" (e.g., Hys5 as described below) is less than the sum of "the EA between the UE and the target candidate cell" (e.g., EAn as described below) and "the EA offset" (e.g., offset3 as described below).

[0108] The entry condition and the departure condition of the EA-based event 1 in the above example can be represented as follows:

[0109] ● Entry condition #3: EAp – Hys5 > EAn + offset3

[0110] ● Departure condition #3: EAp + Hys5 < EAn + offset3

[0111] i. EAp (primary EA) is the EA between the UE and the source cell (e.g., SpCell).

[0112] ii. EAn (adjacent EA) is the EA between the UE and the target candidate cell (e.g., adjacent cell).

[0113] iii. offset3 is optional. offset3 can be a parameter associated with "the measurement object of the UE" or "the satellite". offset3 is cell-specific.

[0114] iv. Hys5 is the hysteresis parameter of the EA-based event 1.

[0115] In another example, the EA-based trigger condition is another EA-based event, that is: the EA value between the UE and the source cell is greater than an EA threshold; and / or the EA between the UE and the target candidate cell is less than another EA threshold. Briefly, this another EA-based event can be referred to as the EA-based event 2. In this example, the set of CHO execution condition parameters received by the UE in operation 302 may include an EA hysteresis parameter and two EA thresholds. In different embodiments, these two EA thresholds can be the same or different.

[0116] The EA-based event 2 may include two entry conditions of the CHO procedure (e.g., entry condition #3-1 and entry condition #3-2 as described below), which may also be referred to as the EA entry conditions. In an embodiment:

[0117] - The entry condition is that the difference between "EA between the UE and the source cell" (e.g., EAp as described below) and "EA hysteresis parameter" (e.g., Hys6 as described below) is greater than the EA threshold (e.g., threshold3 as described below).

[0118] - Another entry condition is that the sum of "EA between the UE and the target candidate cell" (e.g., EAn as described below) and "EA hysteresis parameter" (e.g., Hys6 as described below) is less than another EA threshold (e.g., threshold3' as described below).

[0119] The EA-based event 2 may include two leaving conditions (e.g., leaving condition #3-1 and leaving condition #3-2 as described below) of the CHO procedure, which may also be referred to as EA leaving conditions. In an embodiment:

[0120] - The leaving condition is that the sum of "EA between the UE and the source cell" (e.g., EAp as described below) and "EA hysteresis parameter" (e.g., Hys6 as described below) is less than the EA threshold (e.g., threshold3 as described below).

[0121] - Another leaving condition is that the difference between "EA value between the UE and the target candidate cell" (e.g., EAn as described below) and "EA hysteresis parameter" (e.g., Hys6 as described below) is greater than another EA threshold (e.g., threshold3' as described below).

[0122] The entry conditions and leaving conditions of the EA-based event 2 in the above another example can be represented as follows:

[0123] ● Entry condition #3-1: EAp - Hys6 > threshold3

[0124] ● Entry condition #3-2: EAn + Hys6 < threshold3’

[0125] ● Leaving condition #3-1: EAp + Hys6 < threshold3

[0126] ● Leaving condition #3-2: EAn - Hys6 > threshold3’

[0127] i. Hys6 is the hysteresis parameter of the EA-based event 2.

[0128] Regarding the EA-based trigger condition, the UE may consider an EA-based event whose entry condition is satisfied during a TTT (e.g., TTT1) as satisfied. The UE may consider an EA-based event whose exit condition is satisfied during another TTT (e.g., TTT2) as not satisfied. The length of TTT1 may be the same as or different from the length of TTT2. That is, after the entry condition of an EA-based event (e.g., EA-based event 1 or EA-based event 2) is satisfied during TTT1, the UE considers that the CHO execution condition has been "satisfied" until the exit condition of the EA-based event is satisfied during TTT2. That is to say, once the exit condition of the EA-based event is satisfied during TTT2, the UE considers that the CHO execution condition is "not satisfied".

[0129] In some embodiments of the present application, the CHO execution condition associated with the target candidate cell includes a measurement-based trigger condition of the CHO procedure, that is, event A3 or event A5 as specified in 3GPP TS 38.331.

[0130] Combination method 1

[0131] In some embodiments of the present application, the CHO execution condition associated with the target candidate cell may be a combination of a measurement-based trigger condition and a location-based trigger condition. For example, the CHO execution condition associated with the target candidate cell may be referred to as a "combined CHO trigger condition" and may be one of the following:

[0132] ● A combination of event A3 and location-based event 1.

[0133] ● A combination of event A3 and location-based event 2.

[0134] ● A combination of event A5 and location-based event 1.

[0135] ● A combination of event A5 and location-based event 2.

[0136] In these embodiments, a set of CHO execution condition parameters received in operation 302 may include TTT. Specifically, if the duration for which the entry condition of the location-based event 1 is satisfied is equal to or longer than TTT, and the duration for which the entry condition of event A3 or event A5 is satisfied is equal to or longer than TTT, then the UE may determine that the combined CHO execution condition is satisfied. If the duration for which the entry condition of the location-based event 2 is satisfied is equal to or longer than TTT, and the duration for which the entry condition of event A3 or event A5 is satisfied is equal to or longer than TTT, then the UE may determine that the combined CHO execution condition is satisfied.

[0137] In Option 1, the UE regards the event whose entry condition is satisfied during the TTT as "satisfied", and regards the event whose exit condition is satisfied during the TTT as "not satisfied". That is, the UE starts the CHO procedure only when both events in the combined CHO trigger condition are satisfied. If the measurement-based event is satisfied and the location-based event is also satisfied, then the UE regards the target candidate cell as the trigger cell.

[0138] In some instances of Option 1, in each of the following cases, the UE may determine that the CHO execution condition is not satisfied:

[0139] ● The duration for which the exit condition of the location-based event 1 is satisfied is equal to or longer than the TTT;

[0140] ● The duration for which the exit condition of the location-based event 2 is satisfied is equal to or longer than the TTT;

[0141] ● The duration for which the exit condition of event A3 or event A5 is satisfied is equal to or longer than the TTT; and

[0142] ● The UE determines that at least one of the "entry condition of the location-based event 1, entry condition of the location-based event 2, and entry condition of event A3 or event A5" is not satisfied during the TTT. In other words, if the UE finds that at least one of these entry conditions for the CHO execution condition is not satisfied when the TTT expires, then the UE determines that the combined CHO execution condition is not satisfied.

[0143] In Option 2, the UE regards the event whose entry condition is satisfied during the TTT as "satisfied", and regards the event whose entry condition is not satisfied during the TTT as "not satisfied". In some instances of Option 2, in each of the following cases, the UE may determine that the CHO execution condition is not satisfied:

[0144] ● The duration for which the entry condition of the location-based event 1 is satisfied is shorter than the TTT;

[0145] ● The duration for which the entry condition of the location-based event 2 is satisfied is shorter than the TTT; and

[0146] ● The duration for which the entry condition of event A3 or event A5 is satisfied is shorter than the TTT.

[0147] In some embodiments of the present application, the CHO execution condition associated with the target candidate cell includes the absolute time of the UE.

[0148] Combination method 2

[0149] In some embodiments of the present application, the CHO execution condition associated with the target candidate cell may be a combination of a measurement-based trigger condition and the absolute time of the UE. For example, the CHO execution condition associated with the target candidate cell may be referred to as a "combined CHO trigger condition" and may be one of the following:

[0150] ● A combination of event A3 and the absolute time of the UE.

[0151] ● A combination of event A5 and the absolute time of the UE.

[0152] In the combined CHO trigger condition, if the measurement-based event is first satisfied and the absolute time of the UE is not satisfied (or the timer has not expired), then the UE may consider the target candidate cell as the trigger cell when the absolute time is satisfied (or the timer expires), and the measurement-based event is considered to be "satisfied".

[0153] In an example, if the time instance reaches the absolute time and the duration for which the entry condition of event A3 or event A5 is satisfied is equal to or longer than the TTT, then the UE may determine that the combined CHO execution condition is satisfied.

[0154] In the combined CHO trigger condition, if the absolute time of the UE is first satisfied (or the timer expires) and the measurement-based event is not satisfied, then the UE may start a new timer to control the CHO execution procedure. If no new timer is introduced, then the UE may need to release the corresponding CHO execution procedure. Specifically, a measurement report may be triggered. Once the entry condition is satisfied during the TTT within a period of time, the UE considers the target candidate cell as the trigger cell. Once the new timer expires, the UE stops evaluating the corresponding CHO execution condition. In addition, the UE may release the CHO execution condition.

[0155] In one example, if the time instance reaches the absolute time and the duration for which the entry condition of event A3 or event A5 is satisfied is shorter than the TTT, then the UE may trigger a measurement reporting procedure.

[0156] In another example, if the time instance reaches the absolute time and event A3 or event A5 is not satisfied during the TTT, then the UE starts a timer. When the timer expires, the UE may stop evaluating the CHO execution condition associated with each target candidate cell.

[0157] Combination method 3

[0158] In some embodiments of the present application, the CHO execution condition associated with the target candidate cell may be a combination of a measurement-based trigger condition and a TA-based trigger condition. For example, the CHO execution condition associated with the target candidate cell may be referred to as a "combined CHO trigger condition" and may be one of the following:

[0159] ● The combination of event A3 and TA-based event 1.

[0160] ● The combination of event A3 and TA-based event 2.

[0161] ● The combination of event A5 and TA-based event 1.

[0162] ● The combination of event A5 and TA-based event 2.

[0163] In option 1, the UE considers the target candidate cell as a triggering cell and initiates the CHO procedure only when both the measurement-based event and the TA-based event are satisfied. In some instances of option 1, in each of the following cases, the UE may determine that the combined CHO execution condition is not satisfied:

[0164] ● The duration for which the leaving condition of TA-based event 1 is satisfied is equal to or longer than TTT;

[0165] ● The duration for which the leaving condition of TA-based event 2 is satisfied is equal to or longer than TTT;

[0166] ● The duration for which the leaving condition of event A3 or event A5 is satisfied is equal to or longer than TTT; and

[0167] ● The UE determines that at least one of the "entry conditions of TA-based event 1, entry conditions of TA-based event 2, and entry conditions of event A3 or event A5" is not satisfied during TTT. In other words, if the UE finds that at least one of these entry conditions for the CHO execution condition is not satisfied at the end of TTT, then the UE determines that the combined CHO execution condition is not satisfied.

[0168] In option 2, the UE considers an event whose entry condition is satisfied during TTT as "satisfied" and an event whose entry condition is not satisfied during TTT as "not satisfied". In some instances of option 2, in each of the following cases, the UE may determine that the combined CHO execution condition is not satisfied:

[0169] ● The duration for which the entry condition of TA-based event 1 is satisfied is shorter than TTT;

[0170] ● The duration for which the entry condition of TA-based event 2 is satisfied is shorter than TTT; and

[0171] ● The duration for which the entry condition of event A3 or event A5 is satisfied is shorter than TTT.

[0172] Combination method 4

[0173] In some embodiments of the present application, the CHO execution condition associated with the target candidate cell may be a combination of a measurement-based trigger condition and an EA-based trigger condition. For example, the CHO execution condition associated with the target candidate cell may be referred to as a "combined CHO trigger condition" and may be one of the following:

[0174] ● A combination of event A3 and EA-based event 1.

[0175] ● A combination of event A3 and EA-based event 2.

[0176] ● A combination of event A5 and EA-based event 1.

[0177] ● A combination of event A5 and EA-based event 2.

[0178] In option 1, the UE considers the target candidate cell as a trigger cell and initiates the CHO procedure only when both the measurement-based event and the EA-based event are satisfied. In some instances of option 1, in each of the following cases, the UE may determine that the combined CHO execution condition is not satisfied:

[0179] ● The duration for which the departure condition of EA-based event 1 is satisfied is equal to or longer than TTT;

[0180] ● The duration for which the departure condition of EA-based event 2 is satisfied is equal to or longer than TTT;

[0181] ● The duration for which the departure condition of event A3 or event A5 is satisfied is equal to or longer than TTT; and

[0182] ● The UE determines that at least one of the "entry conditions of EA-based event 1, entry conditions of EA-based event 2, and entry conditions of event A3 or event A5" is not satisfied during TTT. In other words, if the UE finds that at least one of these CHO execution condition entry conditions is not satisfied when TTT expires, then the UE determines that the combined CHO execution condition is not satisfied.

[0183] In option 2, the UE considers an event whose entry condition is satisfied during TTT as "satisfied" and an event whose entry condition is not satisfied during TTT as "not satisfied". In some instances of option 2, in each of the following cases, the UE may determine that the combined CHO execution condition is not satisfied:

[0184] ● The duration for which the entry condition of EA-based event 1 is satisfied is shorter than TTT;

[0185] ● The duration for which the entry condition of EA-based event 2 is satisfied is shorter than TTT; and

[0186] ● The duration for satisfying the entry condition of event A3 or event A5 is shorter than TTT.

[0187] In the embodiments described and shown in Figure 1 , 2 , 4 and 5, the details described, especially those related to the specific operations for handling CHO execution conditions, apply to the embodiments described and shown in Figure 3 . In addition, Figure 3 the details described in the embodiments of Figure 1 , 2 , 4 and 5.

[0188] Figure 4 Exemplary flowchart illustrating a method for transmitting CHO execution condition parameters according to some embodiments of the present application. Figure 4 The embodiments of Figure 1 can be executed by a BS or a source BS (e.g., Figure 4 the BS102 described and shown in

[0189] In the exemplary method 400 shown in Figure 4 , in operation 402, the BS receives a measurement report. For example, the BS receives a measurement report from a UE (e.g., Figure 1 the UE 101-A and UE 101-B described and shown in

[0190] In operation 404, the BS transmits an RRC reconfiguration message. For example, the BS transmits an RRC reconfiguration message to a UE (e.g., Figure 1 the UE 101-A and UE 101-B described and shown in

[0191] According to some embodiments, a set of CHO execution condition parameters includes a distance hysteresis parameter and a distance offset. These parameters can be used for location-based event 1. The distance offset is cell-specific and can be associated with "UE's measurement object" or "satellite".

[0192] According to some embodiments, a set of CHO execution condition parameters includes a distance hysteresis parameter and two distance thresholds. These parameters can be used for location-based event 2.

[0193] According to some embodiments, a set of CHO execution condition parameters includes a TA hysteresis parameter and a TA offset. These parameters can be used for event 1 based on TA. The TA offset is cell-specific and can be associated with "UE's measurement object" or "satellite".

[0194] According to some embodiments, a set of CHO execution condition parameters includes a TA hysteresis parameter and two TA thresholds. These parameters can be used for event 2 based on TA.

[0195] According to some embodiments, a set of CHO execution condition parameters includes an EA hysteresis parameter and an EA offset. These parameters can be used for event 1 based on EA. The EA offset is cell-specific and can be associated with "UE's measurement object" or "satellite".

[0196] According to some embodiments, a set of CHO execution condition parameters includes an EA hysteresis parameter and two EA thresholds. These parameters can be used for event 2 based on EA.

[0197] According to some embodiments, the BS further transmits a mapping table including one or more entries. Each entry may include at least one of the following:

[0198] - A mapping association between "UE's distance information" and the "timing advance (TA) value between the UE and the source cell". The UE (e.g., Figure 1 UE 101-A and UE 101-B as illustrated and shown) can calculate the distance information based on the UE's location information and ephemeris information; and

[0199] - A mapping association between "UE's distance information" and the "TA value between the UE and the target candidate cell".

[0200] In Figures 1 to 3 and the details described in the embodiments illustrated and shown in 5, especially the content related to the specific operations for handling CHO execution conditions and the combination manner of CHO execution conditions, apply to Figure 4 the embodiments illustrated and shown in Figure 4 In addition, the details described in the embodiments of Figures 1 to 3 apply to all embodiments of

[0201] Figure 5 Illustrates an exemplary block diagram of a device according to some embodiments of the present application. In some embodiments of the present application, the device 500 can be a UE, which can at least execute Figure 3 the method illustrated in Figure 4 In some embodiments of the present application, the device 500 can be a BS, which can at least execute

[0202] As Figure 5As shown, device 500 may include at least one receiver 502, at least one transmitter 504, at least one non-transitory computer-readable medium 506, and at least one processor 508, which is coupled to at least one receiver 502, at least one transmitter 504, and at least one non-transitory computer-readable medium 506.

[0203] Although in Figure 5 the elements such as at least one receiver 502, at least one transmitter 504, at least one non-transitory computer-readable medium 506, and at least one processor 508 are described in the singular form, the plural form may be contemplated unless explicitly stated to be limited to the singular. In some embodiments of the present application, at least one receiver 502 and at least one transmitter 504 are combined into a single device, such as a transceiver. In certain embodiments of the present application, device 500 may further include an input device, a memory, and / or other components.

[0204] In some embodiments of the present application, at least one non-transitory computer-readable medium 506 may have computer-executable instructions stored thereon, which are programmed to implement the operations of a method described, for example, in the views of Figure 3 or Figure 4 using at least one receiver 502, at least one transmitter 504, and at least one processor 508.

[0205] Those of ordinary skill in the art will understand that the steps of the methods described in connection with the aspects disclosed herein may be embodied directly in hardware, in software modules executed by a processor, or in a combination of both. The software modules may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. Additionally, in some aspects, the steps of the methods may reside as one or any combination or collection of code and / or instructions on a non-transitory computer-readable medium that may be incorporated into a computer program product.

[0206] While the present disclosure has been described in terms of its specific embodiments, it is apparent that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, the various components of the embodiments may be interchanged, added, or replaced in other embodiments. Additionally, all elements of each figure are not necessary for the operation of the disclosed embodiments. For example, those of ordinary skill in the art of the disclosed embodiments will be able to make and use the teachings of the present disclosure by simply adopting the elements of the independent technical solutions. Accordingly, the embodiments of the present disclosure as described herein are intended to be illustrative and not restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0207] In this document, the term "includes" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "a / an" or the like does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element. Further, the term "another" is defined as at least a second or more. As used herein, the terms "has" and the like are defined as "includes".

Claims

1. An apparatus for handling conditions for performing conditional handover (CHO) in a non-terrestrial network (NTN) environment, the apparatus comprising: at least one non-transitory computer-readable medium storing computer-executable instructions; at least one receiving circuitry; at least one transmitting circuitry; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuitry, and the at least one transmitting circuitry, wherein the computer-executable instructions cause the at least one processor to implement a method, the method comprising: receiving a radio resource control (RRC) reconfiguration message, wherein the RRC reconfiguration message includes conditional handover (CHO) configuration information associated with one or more target candidate cells and a set of CHO execution condition parameters associated with the one or more target candidate cells; evaluating one or more CHO execution conditions associated with each of the one or more target candidate cells; determining whether a CHO execution condition associated with a target candidate cell is satisfied; and in response to the CHO execution condition being satisfied, performing a CHO procedure from a source cell to the target candidate cell, wherein the CHO execution condition includes a second location-based trigger condition, and the second location-based trigger condition is at least one of the following: a first distance between a user equipment (UE) and the source cell is greater than a first distance threshold; or a second distance between the UE and the target candidate cell is less than a second distance threshold.

2. The apparatus according to claim 1, wherein at least one of the source cell or the target candidate cell is a non-terrestrial network (NTN) cell.

3. The apparatus according to claim 1, wherein the CHO execution condition includes a first location-based trigger condition, and the first location-based trigger condition is: a first distance between a user equipment (UE) and the source cell is greater than an offset of a second distance between the UE and the target candidate cell.

4. The apparatus according to claim 1, wherein the set of CHO execution condition parameters includes a second distance hysteresis parameter, the first distance threshold, and the second distance threshold, wherein the second location-based trigger condition includes a second distance entry condition for the CHO procedure, and wherein the second distance entry condition includes one of the following: a difference between the first distance and the second distance hysteresis parameter is greater than the first distance threshold; or a sum of the second distance and the second distance hysteresis parameter is less than the second distance threshold.

5. The apparatus according to claim 4, further comprising: determining that a distance exit condition for the CHO procedure is satisfied in response to at least one of the following: a sum of the first distance and the second distance hysteresis parameter is less than the first distance threshold; or a difference between the second distance and the second distance hysteresis parameter is greater than the second distance threshold.

6. The apparatus according to claim 3, wherein the set of CHO execution condition parameters includes a trigger timer (TTT), and the CHO execution condition is: A combination of a measurement-based trigger condition and the second location-based trigger condition.

7. The apparatus according to claim 6, further comprising: Determining that the CHO execution condition is satisfied in response to the duration of the entry condition for satisfying the second location-based trigger condition being equal to or longer than the TTT and the duration of the entry condition for satisfying the measurement-based trigger condition being equal to or longer than the TTT.

8. The apparatus according to claim 6, further comprising: Determining that the CHO execution condition is not satisfied in response to one of the following: The duration of the exit condition for satisfying the second location-based trigger condition is equal to or longer than the TTT; The duration of the exit condition for satisfying the measurement-based trigger condition is equal to or longer than the TTT; or Determining that at least one of the entry condition for the first location-based trigger condition, the entry condition for the second location-based trigger condition, or the entry condition for the measurement-based trigger condition is not satisfied during the TTT.

9. The apparatus according to claim 1, wherein the set of CHO execution condition parameters includes the absolute time of the user equipment UE.

10. The apparatus according to claim 1, further comprising: Removing the CHO configuration information and the set of CHO execution condition parameters upon successful access to the target candidate cell.

11. An apparatus for handling a conditional handover (CHO) execution condition in a non-terrestrial network (NTN) environment, the apparatus comprising: At least one non-transitory computer-readable medium having computer-executable instructions stored thereon; At least one receiving circuit system; At least one transmitting circuit system; and At least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuit system, and the at least one transmitting circuit system, wherein the computer-executable instructions cause the at least one processor to implement a method, the method comprising: Receiving a measurement report; and Transmitting a radio resource control (RRC) reconfiguration message, wherein the RRC reconfiguration message includes conditional handover (CHO) configuration information associated with one or more target candidate cells and a set of CHO execution condition parameters associated with the one or more target candidate cells, wherein the set of CHO execution condition parameters is related to the CHO execution condition associated with the target candidate cell, and wherein the CHO execution condition includes a second location-based trigger condition, and the second location-based trigger condition is at least one of the following: The first distance between the user equipment UE and the source cell is greater than a first distance threshold; or The second distance between the UE and the target candidate cell is less than a second distance threshold.

12. The apparatus according to claim 11, wherein the set of CHO execution condition parameters includes a first distance hysteresis parameter and a distance offset.

13. The apparatus according to claim 11, wherein the set of CHO execution condition parameters includes a second distance hysteresis parameter, the first distance threshold, and the second distance threshold.

14. The apparatus according to claim 11, wherein the set of CHO execution condition parameters includes a first TA hysteresis parameter and a TA offset.

15. The apparatus according to claim 11, wherein the set of CHO execution condition parameters includes a second TA hysteresis parameter, a first TA threshold, and a second TA threshold.

16. The apparatus according to claim 11, wherein the set of CHO execution condition parameters includes a first EA hysteresis parameter and an EA offset.

17. The apparatus according to claim 11, wherein the set of CHO execution condition parameters includes a trigger timer TTT.

18. The apparatus according to claim 11, further comprising: transmitting a mapping table including one or more entries, wherein the one or more entries include at least one of the following: a mapping association between distance information of the UE and a timing advance TA value between the UE and the source cell; or a mapping association between the distance information of the UE and a TA value between the UE and a target candidate cell.

19. A method for handling conditional handover CHO execution conditions in a non-terrestrial network NTN environment, the method comprising: receiving a radio resource control RRC reconfiguration message, wherein the RRC reconfiguration message includes conditional handover CHO configuration information associated with one or more target candidate cells and a set of CHO execution condition parameters associated with the one or more target candidate cells; evaluating one or more CHO execution conditions associated with each of the one or more target candidate cells; determining whether the CHO execution conditions associated with a target candidate cell are satisfied; and in response to the CHO execution conditions being satisfied, performing a CHO procedure from a source cell to the target candidate cell, wherein the CHO execution conditions include a second location-based trigger condition, and the second location-based trigger condition is at least one of the following: a first distance between a user equipment UE and the source cell is greater than a first distance threshold; or a second distance between the UE and the target candidate cell is less than a second distance threshold.

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