Interruption reduction for cell change procedures

Abstract

In some example embodiments, there may be provided a method comprising: receiving a synchronization command from a serving cell, wherein the synchronization command provides instructions to perform Uplink (UL) and Downlink (DL) synchronization with at least one cell, initiating UL synchronization and DL synchronization with the at least one cell based at least in part on the synchronization command.

Description

[0001] Interruption Reduction for Cell Change Procedures

[0002] FIELD

[0003] Various example embodiments relate to the field of wireless communication and, in particular to cell change procedures and / or to interruption reduction for cell change procedures.

[0004] BACKGROUND

[0005] In the field of wireless communication, mobility management concept(s) exist which include mobility procedures, such as for example Lower Layer Triggered Mobility (LTM) or Layer 1 (L1) / Layer 2 (L2) Triggered Mobility and / or Layer 3 (L3) based mobility, such as handover procedures. In such processes, a cell transition, change and / or switch process may be performed, in particular where an apparatus', e.g. a User Equipment's (UE), serving cell may be changed / switched, e.g. to at least one candidate cell or target cell. However, mobility procedures may be susceptible to interruptions resulting from one or more steps of the procedure. It may be beneficial, among other things, to at least partially reduce and / or minimize a time duration associated with such an interruption. In addition, or alternatively thereto, it may be beneficial to address a signaling overhead related to mobility procedure.

[0006] SUMMARY

[0007] According to some aspects, there is provided the subject matter of the independent claims. Some further aspects, advantages and / or features are defined in the dependent claims, the description and / or the accompanying drawings.

[0008] In a first example aspect, there may be provided an apparatus, comprising:

[0009] at least one processor; and

[0010] at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0011] receiving a synchronization command from a serving cell, wherein the synchronization command provides instructions to perform Uplink (UL) and Downlink (DL) synchronization with at least one cell,initiating UL synchronization and DL synchronization with the at least one cell based at least in part on the synchronization command.

[0012] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect described herein, wherein the synchronization command provides instructions to perform cell configuration processing of at least one cell configuration.

[0013] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is an early synchronization command which is received before at least one of:

[0014] - reception of a cell change command, or

[0015] - execution of a cell change procedure.

[0016] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is a single command.

[0017] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command corresponds to or is included in a single message.

[0018] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is received and / or processed before occurrence of at least one time delay associated to a cell change procedure of the apparatus, wherein the at least one time delay includes at least one of:

[0019] - a processing delay,

[0020] - an acknowledgement delay,

[0021] - a delay for acquiring timing information of the at least one cell,

[0022] - a delay for processing of at least one Reference Signal (RS), including a Synchronization Signal Block (SSB),

[0023] - a processing delay for target cell configuration processing and validity checking, or - a delay associated with a Random Access (RA) procedure.In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to perform UL synchronization and DL synchronization are merged or bundled together in the synchronization command.

[0024] In an example embodiment, which may be referred to as a first example embodiment of the first example aspect, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to perform UL synchronization and DL synchronization include at least one Transmission Configuration Indicator (TCI) state activation instruction.

[0025] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is at least one of: an in-band protocol header, a Medium Access Control (MAC) Control Element (CE) command or an Abstract Syntax Notation One (ASN.1) message.

[0026] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is transmitted by at least one lower layer, wherein the synchronization command is transmitted by a Layer 2 (L2) or a MAC layer.

[0027] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the UL and DL synchronization is performed fora cell change procedure to the at least one cell, wherein the cell change procedure is a Layer 3 (L3) cell change procedure.

[0028] In an example embodiment, which may be referred to as a second example embodiment of the first example aspect, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:receiving at least one cell configuration of the at least one cell from the at least one serving cell.

[0029] In an example embodiment, which may be referred to as a third example embodiment of the first example aspect, there is provided an apparatus, in particular according to the second example embodiment of the first example aspect described herein, wherein the at least one cell configuration is a Radio Resource Control (RRC) configuration of the at least one cell, wherein the at least one cell configuration is received before reception of the synchronization command.

[0030] In an example embodiment, which may be referred to as a fourth example embodiment of the first example aspect, there is provided an apparatus, in particular according to the second example embodiment of the first example aspect and / or the third example embodiment of the first example aspect described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0031] performing cell configuration processing of the at least one cell configuration, based at least in part on the synchronization command,

[0032] wherein cell configuration processing is performed in addition to UL and DL synchronization.

[0033] In an example embodiment, which may be referred to as a fifth example embodiment of the first example aspect, there is provided an apparatus, in particular according to the second example embodiment of the first example aspect, the third example embodiment of the first example aspect and / or the fourth example embodiment of the first example aspect described herein, wherein the at least one cell configuration includes at least one of:

[0034] - at least one measurement configuration,

[0035] - at least one reporting configuration,

[0036] - at least one TCI state information, or

[0037] of the at least one cell.

[0038] In an example embodiment, which may be referred to as a sixth example embodiment of the first example aspect, there is provided an apparatus, in particular according to any one from the first example embodiment of the first example aspect to the fifth example embodiment ofthe first example aspect and / or any one of the example embodiments therebetween, wherein the at least one TCI state activation instruction activates at least one TCI state of the at least one cell.

[0039] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to perform UL synchronization and DL synchronization include an instruction to cause initiation of a Random Access (RA) procedure for UL synchronization.

[0040] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0041] transmitting a Random Access Channel (RACH) preamble for UL synchronization with the at least one cell based at least in part on the synchronization command.

[0042] In an example embodiment, which may be referred to as a seventh example embodiment of the first example aspect, there is provided an apparatus, in particular according to any one from the first example aspect to the sixth example embodiment of the first example aspect and / or any one of the example embodiments therebetween, wherein the instructions to perform UL synchronization and DL synchronization include at least one indication to initiate Timing Advance (TA) estimation for UL synchronization.

[0043] In an example embodiment, there is provided an apparatus, in particular according to any one from the first example aspect to the sixth example embodiment of the first example aspect and / or any one of the example embodiments therebetween or according to the seventh example embodiment of the first example aspect, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0044] performing Timing Advance (TA) estimation for the at least one cell based at least in part on the synchronization command.

[0045] In an example embodiment, which may be referred to as an eighth example embodiment of the first example aspect, there is provided an apparatus, in particular according to the first exampleaspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0046] receiving at least one cell change command from the serving cell after performing UL and DL synchronization.

[0047] In an example embodiment, there is provided an apparatus, in particular according to the eighth example embodiment of the first example aspect, wherein the at least one cell change command is received from a same entity as the synchronization command.

[0048] In an example embodiment, which may be referred to as an ninth example embodiment of the first example aspect, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0049] initiating a cell change procedure based on the initiated UL and DL synchronization with the at least one cell.

[0050] In an example embodiment, there is provided an apparatus, in particular according to the ninth example embodiment of the first example aspect, wherein the cell change procedure is a RACH-less cell change procedure, wherein the cell change procedure is free of at least one delay associated with or included in at least one of: UL synchronization, DL synchronization, or cell configuration processing.

[0051] In an example embodiment, which may be referred to as a tenth example embodiment of the first example aspect, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0052] transmitting an indication to a network that indicates completion of UL and DL synchronization.

[0053] In an example embodiment, which may be referred to as an eleventh example embodiment of the first example aspect, there is provided an apparatus, in particular according to the tenthexample embodiment of the first example aspect, wherein the indication is included in or corresponds to a UL and DL synchronization complete message on the at least one cell.

[0054] In an example embodiment, there is provided an apparatus, in particular according to the tenth example embodiment of the first example aspect and / or the eleventh example embodiment of the first example aspect, wherein the indication is included in or corresponds to at least one preamble transmission on the at least one cell.

[0055] In an example embodiment, there is provided an apparatus, in particular according to the tenth example embodiment of the first example aspect and / or the eleventh example embodiment of the first example aspect, the indication is included in or corresponds to at least one of:

[0056] - an Abstract Syntax Notation One (ASN.1) message,

[0057] - a control header, or

[0058] - a Layer 2 (L2) message

[0059] on the at least one cell.

[0060] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell is a candidate cell of a network.

[0061] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein cell configuration processing includes Abstract Syntax Notation One (ASN.1) decoding.

[0062] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the apparatus is a User equipment (UE) or wherein the apparatus is comprised in a UE.

[0063] Furthermore, in particular further according to the first example aspect, there may be provided an apparatus, comprising means for:receiving a synchronization command from a serving cell, wherein the synchronization command provides instructions to perform Uplink (UL) and Downlink (DL) synchronization with at least one cell,

[0064] initiating UL synchronization and DL synchronization with the at least one cell based at least in part on the synchronization command.

[0065] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect described herein, wherein the synchronization command provides instructions to perform cell configuration processing of at least one cell configuration.

[0066] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is an early synchronization command which is received before at least one of:

[0067] - reception of a cell change command, or

[0068] - execution of a cell change procedure.

[0069] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is a single command.

[0070] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command corresponds to or is included in a single message.

[0071] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is received and / or processed before occurrence of at least one time delay associated to a cell change procedure of the apparatus, wherein the at least one time delay includes at least one of:

[0072] - a processing delay,

[0073] - an acknowledgement delay,

[0074] - a delay for acquiring timing information of the at least one cell,- a delay for processing of at least one Reference Signal (RS), including a Synchronization Signal Block (SSB),

[0075] - a processing delay for target cell configuration processing and validity checking, or - a delay associated with a Random Access (RA) procedure.

[0076] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to perform UL synchronization and DL synchronization are merged or bundled together in the synchronization command.

[0077] In an example embodiment, which may be referred to as a first example embodiment of the first example aspect, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to perform UL synchronization and DL synchronization include at least one Transmission Configuration Indicator (TCI) state activation instruction.

[0078] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is at least one of: an in-band protocol header, a Medium Access Control (MAC) Control Element (CE) command or an Abstract Syntax Notation One (ASN.1) message.

[0079] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is transmitted by at least one lower layer, wherein the synchronization command is transmitted by a Layer 2 (L2) or a MAC layer.

[0080] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the UL and DL synchronization is performed fora cell change procedure to the at least one cell, wherein the cell change procedure is a Layer 3 (L3) cell change procedure.

[0081] In an example embodiment, which may be referred to as a second example embodiment of the first example aspect, there is provided an apparatus, in particular according to the first exampleaspect and / or any one of the associated example embodiments described herein, wherein the means are configured for:

[0082] receiving at least one cell configuration of the at least one cell from the at least one serving cell.

[0083] In an example embodiment, which may be referred to as a third example embodiment of the first example aspect, there is provided an apparatus, in particular according to the second example embodiment of the first example aspect described herein, wherein the at least one cell configuration is a Radio Resource Control (RRC) configuration of the at least one cell, wherein the at least one cell configuration is received before reception of the synchronization command.

[0084] In an example embodiment, which may be referred to as a fourth example embodiment of the first example aspect, there is provided an apparatus, in particular according to the second example embodiment of the first example aspect and / or the third example embodiment of the first example aspect described herein, wherein the means are configured for:

[0085] performing cell configuration processing of the at least one cell configuration, based at least in part on the synchronization command,

[0086] wherein cell configuration processing is performed in addition to UL and DL synchronization.

[0087] In an example embodiment, which may be referred to as a fifth example embodiment of the first example aspect, there is provided an apparatus, in particular according to the second example embodiment of the first example aspect, the third example embodiment of the first example aspect and / or the fourth example embodiment of the first example aspect described herein, wherein the at least one cell configuration includes at least one of:

[0088] - at least one measurement configuration,

[0089] - at least one reporting configuration,

[0090] - at least one TCI state information, or

[0091] of the at least one cell.

[0092] In an example embodiment, which may be referred to as a sixth example embodiment of the first example aspect, there is provided an apparatus, in particular according to any one from the first example embodiment of the first example aspect to the fifth example embodiment ofthe first example aspect and / or any one of the example embodiments therebetween, wherein the at least one TCI state activation instruction activates at least one TCI state of the at least one cell.

[0093] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to perform UL synchronization and DL synchronization include an instruction to cause initiation of a Random Access (RA) procedure for UL synchronization.

[0094] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the means are configured for:

[0095] transmitting a Random Access Channel (RACH) preamble for UL synchronization with the at least one cell based at least in part on the synchronization command.

[0096] In an example embodiment, which may be referred to as a seventh example embodiment of the first example aspect, there is provided an apparatus, in particular according to any one from the first example aspect to the sixth example embodiment of the first example aspect and / or any one of the example embodiments therebetween, wherein the instructions to perform UL synchronization and DL synchronization include at least one indication to initiate Timing Advance (TA) estimation for UL synchronization.

[0097] In an example embodiment, there is provided an apparatus, in particular according to any one from the first example aspect to the sixth example embodiment of the first example aspect and / or any one of the example embodiments therebetween or according to the seventh example embodiment of the first example aspect, wherein the means are configured for: performing Timing Advance (TA) estimation for the at least one cell based at least in part on the synchronization command.

[0098] In an example embodiment, which may be referred to as an eighth example embodiment of the first example aspect, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the means are configured for:receiving at least one cell change command from the serving cell after performing UL and DL synchronization.

[0099] In an example embodiment, there is provided an apparatus, in particular according to the eighth example embodiment of the first example aspect, wherein the at least one cell change command is received from a same entity as the synchronization command.

[0100] In an example embodiment, which may be referred to as an ninth example embodiment of the first example aspect, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the means are configured for:

[0101] initiating a cell change procedure based on the initiated UL and DL synchronization with the at least one cell.

[0102] In an example embodiment, there is provided an apparatus, in particular according to the ninth example embodiment of the first example aspect, wherein the cell change procedure is a RACH-less cell change procedure, wherein the cell change procedure is free of at least one delay associated with or included in at least one of: UL synchronization, DL synchronization, or cell configuration processing.

[0103] In an example embodiment, which may be referred to as a tenth example embodiment of the first example aspect, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the means are configured for:

[0104] transmitting an indication to a network that indicates completion of UL and DL synchronization.

[0105] In an example embodiment, which may be referred to as an eleventh example embodiment of the first example aspect, there is provided an apparatus, in particular according to the tenth example embodiment of the first example aspect, wherein the indication is included in or corresponds to a UL and DL synchronization complete message on the at least one cell.

[0106] In an example embodiment, there is provided an apparatus, in particular according to the tenth example embodiment of the first example aspect and / or the eleventh example embodiment ofthe first example aspect, wherein the indication is included in or corresponds to at least one preamble transmission on the at least one cell.

[0107] In an example embodiment, there is provided an apparatus, in particular according to the tenth example embodiment of the first example aspect and / or the eleventh example embodiment of the first example aspect, the indication is included in or corresponds to at least one of:

[0108] - an Abstract Syntax Notation One (ASN.1) message,

[0109] - a control header, or

[0110] - a Layer 2 (L2) message

[0111] on the at least one cell.

[0112] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell is a candidate cell of a network.

[0113] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein cell configuration processing includes Abstract Syntax Notation One (ASN.1) decoding.

[0114] In an example embodiment, there is provided an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, wherein the apparatus is a User equipment (UE) or wherein the apparatus is comprised in a UE.

[0115] In a second example aspect, there may be provided a method, comprising:

[0116] receiving a synchronization command from a serving cell, wherein the synchronization command provides instructions to perform Uplink (UL) and Downlink (DL) synchronization with at least one cell,

[0117] initiating UL synchronization and DL synchronization with the at least one cell based at least in part on the synchronization command.In an example embodiment, there is provided a method, in particular according to the second example aspect described herein, wherein the synchronization command provides instructions to perform cell configuration processing of at least one cell configuration.

[0118] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is an early synchronization command which is received before at least one of:

[0119] - reception of a cell change command, or

[0120] - execution of a cell change procedure.

[0121] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is a single command.

[0122] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command corresponds to or is included in a single message.

[0123] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is received and / or processed before occurrence of at least one time delay associated to a cell change procedure of an apparatus, wherein the at least one time delay includes at least one of:

[0124] - a processing delay,

[0125] - an acknowledgement delay,

[0126] - a delay for acquiring timing information of the at least one cell,

[0127] - a delay for processing of at least one Reference Signal (RS), including a Synchronization Signal Block (SSB),

[0128] - a processing delay for target cell configuration processing and validity checking, or - a delay associated with a Random Access (RA) procedure.

[0129] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein,wherein the instructions to perform UL synchronization and DL synchronization are merged or bundled together in the synchronization command.

[0130] In an example embodiment, which may be referred to as a first example embodiment of the second example aspect, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to perform UL synchronization and DL synchronization include at least one Transmission Configuration Indicator (TCI) state activation instruction.

[0131] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is at least one of: an in-band protocol header, a Medium Access Control (MAC) Control Element (CE) command or an Abstract Syntax Notation One (ASN.1) message.

[0132] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is transmitted by at least one lower layer, wherein the synchronization command is transmitted by a Layer 2 (L2) or a MAC layer.

[0133] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the UL and DL synchronization is performed fora cell change procedure to the at least one cell, wherein the cell change procedure is a Layer 3 (L3) cell change procedure.

[0134] In an example embodiment, which may be referred to as a second example embodiment of the second example aspect, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the method comprises:

[0135] receiving at least one cell configuration of the at least one cell from the at least one serving cell.

[0136] In an example embodiment, which may be referred to as a third example embodiment of the second example aspect, there is provided a method, in particular according to the secondexample embodiment of the second example aspect described herein, wherein the at least one cell configuration is a Radio Resource Control (RRC) configuration of the at least one cell, wherein the at least one cell configuration is received before reception of the synchronization command.

[0137] In an example embodiment, which may be referred to as a fourth example embodiment of the second example aspect, there is provided a method, in particular according to the second example embodiment of the second example aspect and / or the third example embodiment of the second example aspect described herein, wherein the method comprises:

[0138] performing cell configuration processing of the at least one cell configuration, based at least in part on the synchronization command,

[0139] wherein cell configuration processing is performed in addition to UL and DL synchronization.

[0140] In an example embodiment, which may be referred to as a fifth example embodiment of the second example aspect, there is provided a method, in particular according to the second example embodiment of the second example aspect, the third example embodiment of the second example aspect and / or the fourth example embodiment of the second example aspect described herein, wherein the at least one cell configuration includes at least one of:

[0141] - at least one measurement configuration,

[0142] - at least one reporting configuration,

[0143] - at least one TCI state information, or

[0144] of the at least one cell.

[0145] In an example embodiment, which may be referred to as a sixth example embodiment of the second example aspect, there is provided a method, in particular according to any one from the first example embodiment of the second example aspect to the fifth example embodiment of the second example aspect and / or any one of the example embodiments therebetween, wherein the at least one TCI state activation instruction activates at least one TCI state of the at least one cell.

[0146] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein,wherein the instructions to perform UL synchronization and DL synchronization include an instruction to cause initiation of a Random Access (RA) procedure for UL synchronization.

[0147] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the method comprises:

[0148] transmitting a Random Access Channel (RACH) preamble for UL synchronization with the at least one cell based at least in part on the synchronization command.

[0149] In an example embodiment, which may be referred to as a seventh example embodiment of the second example aspect, there is provided a method, in particular according to any one from the second example aspect to the sixth example embodiment of the second example aspect and / or any one of the example embodiments therebetween, wherein the instructions to perform UL synchronization and DL synchronization include at least one indication to initiate Timing Advance (TA) estimation for UL synchronization.

[0150] In an example embodiment, there is provided a method, in particular according to any one from the second example aspect to the sixth example embodiment of the second example aspect and / or any one of the example embodiments therebetween or according to the seventh example embodiment of the second example aspect, wherein the method comprises:

[0151] performing Timing Advance (TA) estimation for the at least one cell based at least in part on the synchronization command.

[0152] In an example embodiment, which may be referred to as an eighth example embodiment of the second example aspect, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the method comprises:

[0153] receiving at least one cell change command from the serving cell after performing UL and DL synchronization.

[0154] In an example embodiment, there is provided a method, in particular according to the eighth example embodiment of the second example aspect, wherein the at least one cell change command is received from a same entity as the synchronization command.In an example embodiment, which may be referred to as an ninth example embodiment of the second example aspect, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the method comprises:

[0155] initiating a cell change procedure based on the initiated UL and DL synchronization with the at least one cell.

[0156] In an example embodiment, there is provided a method, in particular according to the ninth example embodiment of the second example aspect, wherein the cell change procedure is a RACH-less cell change procedure, wherein the cell change procedure is free of at least one delay associated with or included in at least one of: UL synchronization, DL synchronization, or cell configuration processing.

[0157] In an example embodiment, which may be referred to as a tenth example embodiment of the second example aspect, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the method comprises:

[0158] transmitting an indication to a network that indicates completion of UL and DL synchronization.

[0159] In an example embodiment, which may be referred to as an eleventh example embodiment of the second example aspect, there is provided a method, in particular according to the tenth example embodiment of the second example aspect, wherein the indication is included in or corresponds to a UL and DL synchronization complete message on the at least one cell.

[0160] In an example embodiment, there is provided a method, in particular according to the tenth example embodiment of the second example aspect and / or the eleventh example embodiment of the second example aspect, wherein the indication is included in or corresponds to at least one preamble transmission on the at least one cell.

[0161] In an example embodiment, there is provided a method, in particular according to the tenth example embodiment of the second example aspect and / or the eleventh example embodiment of the second example aspect, the indication is included in or corresponds to at least one of:

[0162] - an Abstract Syntax Notation One (ASN.1) message,- a control header, or

[0163] - a Layer 2 (L2) message

[0164] on the at least one cell.

[0165] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell is a candidate cell of a network.

[0166] In an example embodiment, there is provided a method, in particular according to the second example aspect and / or any one of the associated example embodiments described herein, wherein cell configuration processing includes Abstract Syntax Notation One (ASN.1) decoding.

[0167] In a third example aspect, there may be provided a non-transitory computer readable storage medium comprising program instructions that, when executed by an apparatus, in particular according to the first example aspect and / or any one of the associated example embodiments described herein, causes operations comprising:

[0168] receiving a synchronization command from a serving cell, wherein the synchronization command provides instructions to perform Uplink (UL) and Downlink (DL) synchronization with at least one cell,

[0169] initiating UL synchronization and DL synchronization with the at least one cell based at least in part on the synchronization command.

[0170] The third example aspect may further comprise one or more steps and / or features of the method and / or any one of the associated example embodiments recited in the second example aspect.

[0171] In a fourth example aspect, which in particular may be combined with anyone of the example aspects and / or any one of the associated example embodiments described herein, there may be provided an apparatus, comprising:

[0172] at least one processor; and

[0173] at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:receiving at least one cell change command from at least one serving cell of a network that indicates execution of a cell change procedure to at least one cell of the network,

[0174] performing, based at least in part on the at least one cell change command, at least one of: Uplink (UL) synchronization, Downlink (DL) synchronization, or cell configuration processing for the at least one cell.

[0175] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect described herein, wherein at least one of: UL synchronization, DL synchronization, or cell configuration processing for the at least one cell is performed while maintaining a connection to the at least one serving cell.

[0176] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the apparatus performs at least one of: UL synchronization, DL synchronization or cell configuration processing without causing an interruption to the at least one serving cell.

[0177] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the apparatus is schedulable by the network until completion of at least one of: UL synchronization, DL synchronization, or cell configuration processing.

[0178] In an example embodiment, which may be referred to as a first example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell change command indicates that execution of the cell change procedure to the at least one cell is to be delayed by at least one time delay period.

[0179] In an example embodiment, which may be referred to as a second example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:performing at least one of: the UL synchronization, the DL synchronization or the cell configuration processing during at least one time delay period indicated in the cell change command.

[0180] In an example embodiment, there is provided an apparatus, in particular according to the first example embodiment of the fourth example aspect and / or the second example embodiment of the fourth example aspect, wherein the at least one time delay period is provided by at least one indication included in the cell change command.

[0181] In an example embodiment, there is provided an apparatus, in particular according to the first example embodiment of the fourth example aspect and / or the second example embodiment of the fourth example aspect, wherein the at least one time delay period is implicitly provided or derived based on a type of the cell change command.

[0182] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command is included in or corresponds to at least one of:

[0183] - a Radio Resource Control (RRC) message,

[0184] - an ASN.1 message, or

[0185] - a Medium Access Control (MAC) Control Element (CE) message,

[0186] wherein the cell change command is transmitted by at least one lower layer, including a Layer 2 (L2) ora Layer 3 (L3).

[0187] In an example embodiment, which may be referred to as a third example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0188] transmitting at least one indication to the network that indicates completion of at least one of: UL synchronization, DL synchronization or cell configuration processing.

[0189] In an example embodiment, which may be referred to as a fourth example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein,wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0190] transmitting at least one indication to the network that indicates which steps of UL synchronization, DL synchronization or cell configuration processing decoding are performable without causing an interruption to the at least one serving cell.

[0191] In an example embodiment, which may be referred to as a fifth example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0192] transmitting at least one indication to the network that indicates at least one time period required to perform at least one step of: UL synchronization, DL synchronization or cell configuration processing without causing an interruption to the at least one serving cell.

[0193] In an example embodiment, there is provided an apparatus, in particular according to the third example embodiment of the fourth example aspect, the fourth example embodiment of the fourth example aspect and / or the fifth example embodiment of the fourth example aspect, wherein the at least one indication is transmitted upon initiation of the cell change procedure.

[0194] In an example embodiment, there is provided an apparatus, in particular according to the third example embodiment of the fourth example aspect, the fourth example embodiment of the fourth example aspect and / or the fifth example embodiment of the fourth example aspect, wherein the at least one indication is transmitted before reception of the at least one cell change command.

[0195] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0196] executing the cell change procedure based on completion of at least one of: UL synchronization, DL synchronization, cell configuration processing.In an example embodiment, which may be referred to as a sixth example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change procedure to be performed depends on availability of Timing Advance (TA) information.

[0197] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command includes at least one cell configuration for the cell change procedure.

[0198] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command includes at least one Transmission Configuration Indicator (TCI) state of the at least one cell.

[0199] In an example embodiment, which may be referred to as a seventh example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to any one from the fourth example aspect to the sixth example embodiment of the fourth example aspect and / or any one of the associated example embodiments in between, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0200] receiving at least one cell configuration from the at least one serving cell for the cell change procedure.

[0201] In an example embodiment, there is provided an apparatus, in particular according to the seventh example embodiment of the fourth example aspect, wherein the at least one cell configuration is a Radio Resource Control (RRC) configuration of the at least one cell, wherein the at least one cell configuration is received before reception of the cell change command.

[0202] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell configuration includes at least one of:- at least one measurement configuration,

[0203] - at least one reporting configuration,

[0204] - at least one TCI state information, or

[0205] of the at least one cell.

[0206] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell is a candidate cell of the network.

[0207] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein cell configuration processing includes Abstract Syntax Notation One (ASN.1) decoding.

[0208] In an example embodiment, which may be referred to as an eighth example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein UL synchronization is performed based on a Random Access (RA) or Timing Advance (TA) estimation.

[0209] In an example embodiment, there is provided an apparatus, in particular according to the eighth example embodiment of the fourth example aspect, wherein the UL synchronization is performed without causing an interruption to the at least one serving cell.

[0210] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the apparatus performs at least one of: UL synchronization, DL synchronization or cell configuration processing before execution of the cell change procedure.

[0211] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the apparatus is a User equipment (UE) or wherein the apparatus is comprised in a UE.Furthermore, in particular further according to the fourth example aspect, there may be provided an apparatus, comprising means for:

[0212] receiving at least one cell change command from at least one serving cell of a network that indicates execution of a cell change procedure to at least one cell of the network,

[0213] performing, based at least in part on the at least one cell change command, at least one of: Uplink (UL) synchronization, Downlink (DL) synchronization, or cell configuration processing for the at least one cell.

[0214] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect described herein, wherein at least one of: UL synchronization, DL synchronization, or cell configuration processing for the at least one cell is performed while maintaining a connection to the at least one serving cell.

[0215] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the apparatus performs at least one of: UL synchronization, DL synchronization or cell configuration processing without causing an interruption to the at least one serving cell.

[0216] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the apparatus is schedulable by the network until completion of at least one of: UL synchronization, DL synchronization, or cell configuration processing.

[0217] In an example embodiment, which may be referred to as a first example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell change command indicates that execution of the cell change procedure to the at least one cell is to be delayed by at least one time delay period.

[0218] In an example embodiment, which may be referred to as a second example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to thefourth example aspect and / or any one of the associated example embodiments described herein, wherein the means are configured for:

[0219] performing at least one of: the UL synchronization, the DL synchronization or the cell configuration processing during at least one time delay period indicated in the cell change command.

[0220] In an example embodiment, there is provided an apparatus, in particular according to the first example embodiment of the fourth example aspect and / or the second example embodiment of the fourth example aspect, wherein the at least one time delay period is provided by at least one indication included in the cell change command.

[0221] In an example embodiment, there is provided an apparatus, in particular according to the first example embodiment of the fourth example aspect and / or the second example embodiment of the fourth example aspect, wherein the at least one time delay period is implicitly provided or derived based on a type of the cell change command.

[0222] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command is included in or corresponds to at least one of:

[0223] - a Radio Resource Control (RRC) message,

[0224] - an ASN.1 message, or

[0225] - a Medium Access Control (MAC) Control Element (CE) message,

[0226] wherein the cell change command is transmitted by at least one lower layer, including a Layer 2 (L2) ora Layer 3 (L3).

[0227] In an example embodiment, which may be referred to as a third example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the means are configured for:

[0228] transmitting at least one indication to the network that indicates completion of at least one of: UL synchronization, DL synchronization or cell configuration processing.

[0229] In an example embodiment, which may be referred to as a fourth example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourthexample aspect and / or any one of the associated example embodiments described herein, wherein the means are configured for:

[0230] transmitting at least one indication to the network that indicates which steps of UL synchronization, DL synchronization or cell configuration processing decoding are performable without causing an interruption to the at least one serving cell.

[0231] In an example embodiment, which may be referred to as a fifth example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the means are configured for:

[0232] transmitting at least one indication to the network that indicates at least one time period required to perform at least one step of: UL synchronization, DL synchronization or cell configuration processing without causing an interruption to the at least one serving cell.

[0233] In an example embodiment, there is provided an apparatus, in particular according to the third example embodiment of the fourth example aspect, the fourth example embodiment of the fourth example aspect and / or the fifth example embodiment of the fourth example aspect, wherein the at least one indication is transmitted upon initiation of the cell change procedure.

[0234] In an example embodiment, there is provided an apparatus, in particular according to the third example embodiment of the fourth example aspect, the fourth example embodiment of the fourth example aspect and / or the fifth example embodiment of the fourth example aspect, wherein the at least one indication is transmitted before reception of the at least one cell change command.

[0235] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the means are configured for:

[0236] executing the cell change procedure based on completion of at least one of: UL synchronization, DL synchronization, cell configuration processing.

[0237] In an example embodiment, which may be referred to as a sixth example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein,wherein the cell change procedure to be performed depends on availability of Timing Advance (TA) information.

[0238] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command includes at least one cell configuration for the cell change procedure.

[0239] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command includes at least one Transmission Configuration Indicator (TCI) state of the at least one cell.

[0240] In an example embodiment, which may be referred to as a seventh example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to any one from the fourth example aspect to the sixth example embodiment of the fourth example aspect and / or any one of the associated example embodiments in between, wherein the means are configured for:

[0241] receiving at least one cell configuration from the at least one serving cell for the cell change procedure.

[0242] In an example embodiment, there is provided an apparatus, in particular according to the seventh example embodiment of the fourth example aspect, wherein the at least one cell configuration is a Radio Resource Control (RRC) configuration of the at least one cell, wherein the at least one cell configuration is received before reception of the cell change command.

[0243] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell configuration includes at least one of:

[0244] - at least one measurement configuration,

[0245] - at least one reporting configuration,

[0246] - at least one TCI state information, or

[0247] of the at least one cell.In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell is a candidate cell of the network.

[0248] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein cell configuration processing includes Abstract Syntax Notation One (ASN.1) decoding.

[0249] In an example embodiment, which may be referred to as an eighth example embodiment of the fourth example aspect, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein UL synchronization is performed based on a Random Access (RA) or Timing Advance (TA) estimation.

[0250] In an example embodiment, there is provided an apparatus, in particular according to the eighth example embodiment of the fourth example aspect, wherein the UL synchronization is performed without causing an interruption to the at least one serving cell.

[0251] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the apparatus performs at least one of: UL synchronization, DL synchronization or cell configuration processing before execution of the cell change procedure.

[0252] In an example embodiment, there is provided an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, wherein the apparatus is a User equipment (UE) or wherein the apparatus is comprised in a UE.

[0253] In a fifth example aspect, which in particular may be combined with any one of the example aspects and / or any one of the associated example embodiments described herein, there may be provided a method, comprising:receiving at least one cell change command from at least one serving cell of a network that indicates execution of a cell change procedure to at least one cell of the network,

[0254] performing, based at least in part on the at least one cell change command, at least one of: Uplink (UL) synchronization, Downlink (DL) synchronization, or cell configuration processing for the at least one cell.

[0255] In an example embodiment, there is provided a method, in particular according to the fifth example aspect described herein, wherein at least one of: UL synchronization, DL synchronization, or cell configuration processing for the at least one cell is performed while maintaining a connection to the at least one serving cell.

[0256] In an example embodiment, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein at least one of: UL synchronization, DL synchronization or cell configuration processing is performed without causing an interruption to the at least one serving cell.

[0257] In an example embodiment, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein an apparatus is schedulable by the network until completion of at least one of: UL synchronization, DL synchronization, or cell configuration processing.

[0258] In an example embodiment, which may be referred to as a first example embodiment of the fifth example aspect, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell change command indicates that execution of the cell change procedure to the at least one cell is to be delayed by at least one time delay period.

[0259] In an example embodiment, which may be referred to as a second example embodiment of the fifth example aspect, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the method comprises:performing at least one of: the UL synchronization, the DL synchronization or the cell configuration processing during at least one time delay period indicated in the cell change command.

[0260] In an example embodiment, there is provided a method, in particular according to the first example embodiment of the fifth example aspect and / or the second example embodiment of the seventh eighth aspect, wherein the at least one time delay period is provided by at least one indication included in the cell change command.

[0261] In an example embodiment, there is provided a method, in particular according to the first example embodiment of the fifth example aspect and / or the second example embodiment of the fifth example aspect, wherein the at least one time delay period is implicitly provided or derived based on a type of the cell change command.

[0262] In an example embodiment, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command is included in or corresponds to at least one of:

[0263] - a Radio Resource Control (RRC) message,

[0264] - an ASN.1 message, or

[0265] - a Medium Access Control (MAC) Control Element (CE) message,

[0266] wherein the cell change command is transmitted by at least one lower layer, including a Layer 2 (L2) ora Layer 3 (L3).

[0267] In an example embodiment, which may be referred to as a third example embodiment of the fifth example aspect, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the method comprises:

[0268] transmitting at least one indication to the network that indicates completion of at least one of: UL synchronization, DL synchronization or cell configuration processing.

[0269] In an example embodiment, which may be referred to as a fourth example embodiment of the fifth example aspect, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the method comprises:transmitting at least one indication to the network that indicates which steps of UL synchronization, DL synchronization or cell configuration processing decoding are performable without causing an interruption to the at least one serving cell.

[0270] In an example embodiment, which may be referred to as a fifth example embodiment of the fifth example aspect, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the method comprises:

[0271] transmitting at least one indication to the network that indicates at least one time period required to perform at least one step of: UL synchronization, DL synchronization or cell configuration processing without causing an interruption to the at least one serving cell.

[0272] In an example embodiment, there is provided a method, in particular according to the third example embodiment of the fifth example aspect, the fourth example embodiment of the fifth example aspect and / or the fifth example embodiment of the fifth example aspect, wherein the at least one indication is transmitted upon initiation of the cell change procedure.

[0273] In an example embodiment, there is provided a method, in particular according to the third example embodiment of the fifth example aspect, the fourth example embodiment of the fifth example aspect and / or the fifth example embodiment of the fifth example aspect, wherein the at least one indication is transmitted before reception of the at least one cell change command.

[0274] In an example embodiment, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the method comprises:

[0275] executing the cell change procedure based on completion of at least one of: UL synchronization, DL synchronization, cell configuration processing.

[0276] In an example embodiment, which may be referred to as a sixth example embodiment of the fifth example aspect, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change procedure to be performed depends on availability of Timing Advance (TA) information.In an example embodiment, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command includes at least one cell configuration for the cell change procedure.

[0277] In an example embodiment, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command includes at least one Transmission Configuration Indicator (TCI) state of the at least one cell.

[0278] In an example embodiment, which may be referred to as a seventh example embodiment of the fifth example aspect, there is provided a method, in particular according to any one from the fifth example aspect to the sixth example embodiment of the fifth example aspect and / or any one of the associated example embodiments in between, wherein the method comprises:

[0279] receiving at least one cell configuration from the at least one serving cell for the cell change procedure.

[0280] In an example embodiment, there is provided a method, in particular according to the seventh example embodiment of the fifth example aspect, wherein the at least one cell configuration is a Radio Resource Control (RRC) configuration of the at least one cell, wherein the at least one cell configuration is received before reception of the cell change command.

[0281] In an example embodiment, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell configuration includes at least one of:

[0282] - at least one measurement configuration,

[0283] - at least one reporting configuration,

[0284] - at least one TCI state information, or

[0285] of the at least one cell.

[0286] In an example embodiment, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell is a candidate cell of the network.In an example embodiment, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein cell configuration processing includes Abstract Syntax Notation One (ASN.1) decoding.

[0287] In an example embodiment, which may be referred to as an eighth example embodiment of the fifth example aspect, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein UL synchronization is performed based on a Random Access (RA) or Timing Advance (TA) estimation.

[0288] In an example embodiment, there is provided a method, in particular according to the eighth example embodiment of the fifth example aspect, wherein the UL synchronization is performed without causing an interruption to the at least one serving cell.

[0289] In an example embodiment, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein at least one of: UL synchronization, DL synchronization or cell configuration processing is performed before execution of the cell change procedure.

[0290] In an example embodiment, there is provided a method, in particular according to the fifth example aspect and / or any one of the associated example embodiments described herein, wherein the apparatus is a User equipment (UE) or wherein the apparatus is comprised in a UE.

[0291] In a sixth example aspect, there may be provided a non-transitory computer readable storage medium comprising program instructions that, when executed by an apparatus, in particular according to the fourth example aspect and / or any one of the associated example embodiments described herein, causes operations comprising:

[0292] receiving at least one cell change command from at least one serving cell of a network that indicates execution of a cell change procedure to at least one cell of the network,performing, based at least in part on the at least one cell change command, at least one of: Uplink (UL) synchronization, Downlink (DL) synchronization, or cell configuration processing for the at least one cell.

[0293] The sixth example aspect may further comprise one or more steps and / or features of the method and / or any one of the associated example embodiments recited in the fifth example aspect.

[0294] In a seventh example aspect, in particular which may be combined with any one of the example aspects and / or any one of the associated example embodiments described herein, there may be provided an apparatus, in particular a node of a network, comprising:

[0295] at least one processor; and

[0296] at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0297] transmitting a synchronization command, wherein the synchronization command provides instructions to at least one of: initiate or perform Uplink (UL) and Downlink (DL) synchronization with at least one cell.

[0298] In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect described herein, wherein the synchronization command provides instructions to at least one of: initiate or perform cell configuration processing of at least one cell configuration.

[0299] In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is an early synchronization command which is transmitted before at least one of:

[0300] - transmission of a cell change command, or

[0301] - execution of a cell change procedure.

[0302] In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is transmitted to at least one User Equipment (UE).In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the node of the network comprises at least one serving cell which is associated with at least one User Equipment (UE).

[0303] In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is a single command.

[0304] In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command corresponds to or is included in a single message.

[0305] In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to at least one of: initiate or perform UL synchronization and DL synchronization are merged or bundled together in the synchronization command.

[0306] In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to at least one of: initiate or perform UL synchronization and DL synchronization include at least one Transmission Configuration Indicator (TCI) state activation instruction.

[0307] In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to at least one of: initiate or perform UL synchronization and DL synchronization include an instruction to cause initiation of a Random Access (RA) procedure for UL synchronization.

[0308] In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described1

[0309] herein, wherein the instructions to at least one of: initiate or perform UL synchronization and DL synchronization include at least one indication to initiate Timing Advance (TA) estimation for UL synchronization.

[0310] In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is at least one of: an in-band protocol header, a Medium Access Control (MAC) Control Element (CE) command or an Abstract Syntax Notation One (ASN.1) message.

[0311] In an example embodiment, there is provided an apparatus, in particular according to the tenth h example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is transmitted by at least one lower layer, wherein the synchronization command is transmitted by a Layer 2 (L2) or a MAC layer.

[0312] In an example embodiment, which may be referred to as a first example embodiment of the seventh example aspect, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus, in particular the node of the network, at least to perform:

[0313] transmitting at least one cell configuration of the at least one cell, in particular to at least one User Equipment (UE).

[0314] In an example embodiment, there is provided an apparatus, in particular according to the first example embodiment of the seventh example aspect described herein, wherein the at least one cell configuration is a Radio Resource Control (RRC) configuration of the at least one cell, wherein the at least one cell configuration is transmitted before transmission of the synchronization command.

[0315] In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructionsthat, when executed by the at least one processor, cause the apparatus, in particular the node of the network, at least to perform:

[0316] transmitting at least one cell change command after transmission of the synchronization command, in particular to at least one User Equipment (UE).

[0317] In an example embodiment, which may be referred to as a second example embodiment of the seventh example aspect, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus, in particular the node of the network, at least to perform:

[0318] receiving at least one indication that indicates completion of UL and DL synchronization.

[0319] In an example embodiment, which may be referred to as a third example embodiment of the seventh example aspect, there is provided an apparatus, in particular according to the second example embodiment of the seventh example aspect described herein, wherein the at least one indication is included in or corresponds to a UL and DL synchronization complete message.

[0320] In an example embodiment, there is provided an apparatus, in particular according to the second example embodiment of the seventh example aspect and / or the third example embodiment of the seventh example aspect described herein, wherein the at least one indication is included in or corresponds to at least one preamble transmission.

[0321] In an example embodiment, there is provided an apparatus, in particular according to the second example embodiment of the seventh example aspect and / or the third example embodiment of the seventh example aspect described herein, wherein the at least one indication is included in or corresponds to at least one of:

[0322] - an Abstract Syntax Notation One (ASN.1) message,

[0323] - a control header, or

[0324] - a Layer 2 (L2) message.In an example embodiment, there is provided an apparatus, in particular according to the seventh example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell is a candidate cell of the network.

[0325] In an eighth example aspect, in particular which may be combined with any one of the example aspects and / or any one of the associated example embodiments described herein, there may be provided a signal or an electronic carrier, with embedded data, being encoded in accordance with an encoding process, which comprises:

[0326] providing a synchronization command, wherein the synchronization command provides instructions to at least one of: initiate or perform Uplink (UL) and Downlink (DL) synchronization with at least one cell.

[0327] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the eighth example aspect described herein, wherein the synchronization command provides instructions to at least one of: initiate or perform cell configuration processing of at least one cell configuration.

[0328] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the eighth example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is a single command.

[0329] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the eighth example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command corresponds to or is included in a single message.

[0330] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the eighth example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to at least one of: initiate or perform UL synchronization and DL synchronization are merged or bundled together in the synchronization command.

[0331] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the eighth example aspect and / or any one of the associated exampleembodiments described herein, wherein the instructions to at least one of: initiate or perform UL synchronization and DL synchronization include at least one Transmission Configuration Indicator (TCI) state activation instruction.

[0332] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the eighth example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to at least one of: initiate or perform UL synchronization and DL synchronization include an instruction to cause initiation of a Random Access (RA) procedure for UL synchronization.

[0333] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the eighth example aspect and / or any one of the associated example embodiments described herein, wherein the instructions to at least one of: initiate or perform UL synchronization and DL synchronization include at least one indication to initiate Timing Advance (TA) estimation for UL synchronization.

[0334] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the eighth example aspect and / or any one of the associated example embodiments described herein, wherein the synchronization command is at least one of: an in-band protocol header, a Medium Access Control (MAC) Control Element (CE) command or an Abstract Syntax Notation One (ASN.1) message.

[0335] In a ninth example aspect, in particular which may be combined with any one of the example aspects and / or any one of the associated example embodiments described herein, there may be provided an apparatus, in particular a node of a network, comprising:

[0336] at least one processor; and

[0337] at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:

[0338] transmitting at least one cell change command that indicates execution of a cell change procedure to at least one cell of the network, wherein the at least one cell change command indicates at least one of: to initiate or to perform at least one of: Uplink (UL) synchronization, Downlink (DL) synchronization, or cell configuration processing for the at least one cell.In an example embodiment, there is provided an apparatus, in particular according to the ninth example aspect described herein, wherein the at least one cell change command is transmitted to at least one User Equipment (UE).

[0339] In an example embodiment, there is provided an apparatus, in particular according to the ninth example aspect and / or any one of the associated example embodiments described herein, wherein the node of the network comprises at least one serving cell which is associated with at least one User Equipment (UE).

[0340] In an example embodiment, which may be referred to as a first example embodiment of the ninth example aspect, there is provided an apparatus, in particular according to the ninth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell change command indicates that execution of the cell change procedure to the at least one cell is to be delayed by at least one time delay period.

[0341] In an example embodiment, there is provided an apparatus, in particular according to the first example embodiment of the ninth example aspect, wherein the at least one time delay period is provided by at least one indication included in the cell change command.

[0342] In an example embodiment, there is provided an apparatus, in particular according to the first example embodiment of the ninth example aspect, wherein the at least one time delay period is implicitly provided or derived based on a type of the cell change command.

[0343] In an example embodiment, there is provided an apparatus, in particular according to the ninth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command is included in or corresponds to at least one of:

[0344] - a Radio Resource Control (RRC) message,

[0345] - an ASN.1 message, or

[0346] - a Medium Access Control (MAC) Control Element (CE) message.

[0347] In an example embodiment, there is provided an apparatus, in particular according to the ninth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command is transmitted by at least one lower layer, including a Layer 2 (L2) ora Layer 3 (L3).In an example embodiment, which may be referred to as a second example embodiment of the ninth example aspect, there is provided an apparatus, in particular according to the ninth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus, in particular the node of the network, at least to perform:

[0348] receiving at least one indication that indicates completion of at least one of: UL synchronization, DL synchronization or cell configuration processing.

[0349] In an example embodiment, which may be referred to as a third example embodiment of the ninth example aspect, there is provided an apparatus, in particular according to the second example embodiment of the ninth example aspect, wherein the at least one indication indicates which steps of UL synchronization, DL synchronization or cell configuration processing decoding are performable without causing an interruption to the network node, in particular to the at least one serving cell.

[0350] In an example embodiment, there is provided an apparatus, in particular according to the second example embodiment of the ninth example aspect and / or the third example embodiment of the ninth example aspect, wherein the at least one indication indicates at least one time period required to perform at least one step of: UL synchronization, DL synchronization or cell configuration processing without causing an interruption to the at least one serving cell.

[0351] In an example embodiment, there is provided an apparatus, in particular according to the second example embodiment of the ninth example aspect and / or the third example embodiment of the ninth example aspect, wherein the at least one indication the at least one indication is received upon initiation of a cell change procedure.

[0352] In an example embodiment, there is provided an apparatus, in particular according to the second example embodiment of the ninth example aspect and / or the third example embodiment of the ninth example aspect, wherein the at least one indication is received before transmission of the at least one cell change command.In an example embodiment, there is provided an apparatus, in particular according to the ninth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command includes at least one cell configuration for the cell change procedure.

[0353] In an example embodiment, there is provided an apparatus, in particular according to the ninth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command includes at least one Transmission Configuration Indicator (TCI) state of the at least one cell.

[0354] In an example embodiment, which may be referred to as a fourth example embodiment of the ninth example aspect, there is provided an apparatus, in particular according to the ninth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus, in particular the node of the network, at least to perform:

[0355] transmitting at least one cell configuration for the cell change procedure.

[0356] In an example embodiment, which may be referred to as a fifth example embodiment of the ninth example aspect, there is provided an apparatus, in particular according to the fourth example embodiment of the ninth example aspect, wherein the at least one cell configuration is a Radio Resource Control (RRC) configuration of the at least one cell, wherein the at least one cell configuration is transmitted before transmission of the cell change command.

[0357] In an example embodiment, there is provided an apparatus, in particular according to the fourth example embodiment of the ninth example aspect and / or the fifth example embodiment of the ninth example aspect, wherein the at least one cell configuration includes at least one of:

[0358] - at least one measurement configuration,

[0359] - at least one reporting configuration,

[0360] - at least one TCI state information, or

[0361] of the at least one cell.In an example embodiment, there is provided an apparatus, in particular according to the ninth example aspect and / or any one of the associated example embodiments described herein, wherein the at least one cell is a candidate cell of the network.

[0362] In a tenth example aspect, in particular which may be combined with any one of the example aspects and / or any one of the associated example embodiments described herein, there may be provided a signal or an electronic carrier, with embedded data, being encoded in accordance with an encoding process, which comprises:

[0363] providing at least one cell change command that indicates execution of a cell change procedure to at least one cell of the network, wherein the at least one cell change command indicates at least one of: to initiate or to perform at least one of: Uplink (UL) synchronization, Downlink (DL) synchronization, or cell configuration processing for the at least one cell.

[0364] In an example embodiment, which may be referred to as a first example embodiment of the tenth example aspect, there is provided a signal or an electronic carrier, in particular according to the tenth example aspect described herein, wherein the at least one cell change command indicates that execution of the cell change procedure to the at least one cell is to be delayed by at least one time delay period.

[0365] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the first example embodiment of the tenth example aspect, wherein the at least one time delay period is provided by at least one indication included in the cell change command.

[0366] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the first example embodiment of the tenth example aspect, wherein the at least one time delay period is implicitly provided or derived based on a type of the cell change command.

[0367] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the tenth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command is included in or corresponds to at least one of:

[0368] - a Radio Resource Control (RRC) message,- an ASN.1 message, or

[0369] - a Medium Access Control (MAC) Control Element (CE) message.

[0370] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the tenth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command includes at least one cell configuration for the cell change procedure.

[0371] In an example embodiment, there is provided a signal or an electronic carrier, in particular according to the tenth example aspect and / or any one of the associated example embodiments described herein, wherein the cell change command includes at least one Transmission Configuration Indicator (TCI) state of the at least one cell.

[0372] BRIEF DESCRIPTION OF THE DRAWINGS

[0373] Some example embodiments will now be described with reference to the accompanying drawings.

[0374] A full and enabling disclosure to one of ordinary skill in the art is set forth more particularly in the remainder of the specification including reference to the accompanying drawings wherein:

[0375] FIG. 1a shows an example signaling with example delays according to subject-matter described herein;

[0376] FIG. 1b shows an example signaling diagram according to subject-matter described herein, in particular in connection with Fig. 1a;

[0377] FIG. 2a shows an example signaling with example delays according to subject-matter described herein;

[0378] FIG. 2b shows an example signaling diagram according to subject-matter described herein, in particular in connection with Fig. 2a;FIG. 3a shows an example signaling with example delays according to subject-matter described herein;

[0379] FIG. 3b shows an example signaling diagram according to subject-matter described herein, in particular in connection with Fig. 3a;

[0380] FIG. 4a shows an example signaling diagram according to subject-matter described herein;

[0381] FIG. 4b shows an example signaling diagram according to subject-matter described herein, in particular in connection with Fig. 4a;

[0382] Fig. 5 shows a flow chart of an example aspect of the subject-matter described herein, and

[0383] Fig. 6 shows a flow chart of an example aspect of the subject-matter described herein.

[0384] DETAILED DESCRIPTION

[0385] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers may refer to same components. Generally, only the differences with respect to individual embodiments may be described. Each example may be provided by way of explanation and is not meant as a limitation. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.

[0386] The drawings are schematic drawings which are not drawn to scale. Some elements in the drawings may have dimensions which are exaggerated for the purpose of highlighting aspects of the present disclosure and / or for the sake of clarity of presentation.

[0387] A "mobility procedure" may be regarded as or may refer to a process of transitioning an apparatus, in particular a User Equipment (UE) (for example a smart phone or other wirelessterminal device), from one network entity (e.g. a cell, beam, or access point) to another network entity, in particular to maintain seamless connectivity. Mobility may be to ensure continuous communication as users move across different coverage areas. It may prevent call drops and / or data session interruptions. Mobility procedures may also be referred to as cell transition procedures. Non-limiting examples for mobility procedures are handovers (HO), which may occur in a higher layer(s), e.g. Layer 3 (L3) and / or cell changes / switches, which may occur in lower layers, e.g. Layer 1 (L1) / Layer 2 (L2). A "mobility procedure" may also refer to beam management or intra-cell mobility, wherein the UE may be switched, e.g. from one (serving) beam to another (new) serving beam.

[0388] "Lower Layer Triggered Mobility” "(LTM) or "Layer 1 (L1) / Layer2 (L2) Triggered Mobility" may refer to a particular mobility procedure, e.g. initiated in a cellular network based on events and / or measurements detected at lower layers of a protocol stack - for example, a physical layer or Layer 1 and / or a data link layer or Layer 2 etc. LTM may provide mechanisms, e.g. for a network node and User Equipment (UE), to address mobility needs, complementing, e.g., higher-layer (e.g. Layer 3 or Radio Resource Control (RRC)) mobility processes. LTM may include a cell change / switch procedure, e.g. where a UE's serving cell (for example a Primary Cell (PCell), PSCell, ora Secondary Cell (SCell)) may be changed / switched, e.g. by a network node, for example by sending a message, e.g. a cell change / switch command or LTM cell change / switch command. An LTM cell change / switch command may be assumed to be delivered by Medium Access Control (MAC) signaling, in particular using a MAC Control Element (CE). Hence, not using RRC signaling as a L3 based handover may be a method for changing between cells.

[0389] As set forth, LTM may be regarded as a mobility procedure where the UE (User Equipment) can change / switch cells quickly based on UE measurements, e.g. without requiring a full handover procedure. The process may be designed to minimize service interruption by allowing, for example early synchronization, such as UL / DL synchronization, and / or timing acquisition, e.g. with candidate or target cells, for example before the switch happens. A LTM cell switch-decision may be based on measurements (for example L1 or L3 measurements) that may be performed and / or reported (for example via a corresponding L1 or L3 measurement report), e.g. by the UE. Before the cell switch, network may optionally activate one or more TCI state(s) for one or more candidate cells. Once a candidate cell TCI state is activated the UE may start tracking the time / frequency synchronization, e.g. using the reference signalsassociated with the activated TCI state(s). The UE may also perform early UL synchronization before the cell switch, for example if this is requested by the network.

[0390] A general but non-limiting LTM mobility procedure may be described as follows. The apparatus, e.g. the UE, may be connected to a cell, e.g. a serving cell, which may be referred to a connected mode or Radio Resource Control (RRC) connected mode. The apparatus, e.g. the UE may perform radio measurements on the serving and / or neighboring cell(s) based on its measurement configuration, e.g. provided by the network. Then, the apparatus, e.g. the UE may transmit a measurement report in a message, in particular a Measurement Report message, to the base station, e.g. gNodeB or gNB. The base station may analyze the measurement report and determine, decide and / or initiate LTM preparation or LTM candidate preparation, for example by selecting candidate / target cell(s) that the UE can switch to. The base station may transmit a message, in particular a RRC Reconfiguration message to the apparatus, e.g. the UE, which may include at least one mobility configuration or cell configuration (these terms may be used interchangeably herein), in particular at least one LTM candidate configuration. The mobility / cell configuration may include and / or define a set of potential (one or more) target cell(s) (or candidate cell(s)) for a future LTM cell switch / change (these terms may be used interchangeably herein). The apparatus, e.g. the UE, may store the mobility / cell configuration, e.g. for later use. Then, the apparatus, e.g. the UE, may acknowledge, in particular successful, reception by transmitting an RRCReconfigurationComplete message back to the gNB. Before receiving the actual cell switch command, the apparatus, e.g. the UE, may start or initiate downlink (DL) synchronization with the candidate or target cell(s) for example based on a received TCI state activation command, such as MAC-CE. Through TCI state activation, e.g. MAC-CE, the network may decide to activate one or more TCI states, in particular for one or more of the configured candidate cells. This step may ensure that when the cell switch command arrives, the apparatus, e.g. the UE, is already aligned with the candidate cell(s) downlink transmission. Thereafter, the apparatus, e.g. the UE, may perform early Timing Advance (TA) acquisition with the candidate cell(s), e.g. as requested by the network before receiving the cell switch command. Timing Advance (TA) may be required to compensate for the signal propagation delay between the apparatus, e.g. the UE, and the base station. For example, the network may request the apparatus, e.g. the UE, to perform early TA acquisition using Contention-Free Random Access (CFRA) before the switch happens. To do so, the serving cell (source gNB) may transmit a Physical Downlink Control Channel (PDCCH) order to the apparatus, e.g. theUE, instructing / triggering it to transmit a preamble to the indicated target (candidate) cell. The apparatus, e.g. the UE, may transmit the preamble to the indicated candidate cell. In order to minimize the data interruption of the source cell due to CFRA towards the candidate cell(s), the apparatus, e.g. the UE, may not receive Random Access Response (RAR) from the network. Instead, the Timing Advance (TA) value for the candidate cell may be provided / indicated later in the actual cell switch command. The apparatus, e.g. the UE, may not maintain a TA timer for the candidate cell; instead, it may rely on the network to ensure the validity of the TA. While waiting for a potential cell switch / change, the apparatus, e.g. the UE may, in particular continuously, perform L1 and / or (Layer 1) measurements on the candidate cells. The apparatus, e.g. the UE, may transmit L1 and / or measurement reports to the gNB, e.g. assisting the network make an informed decision about when and / or where to switch. The apparatus, e.g. the UE, may continue L1 and / or L3 measurements as long as the RRCReconfiguration (s. above) remains valid. Based on the L1 or L3 measurement reports, the gNB may decide to switch the apparatus, e.g. the UE, to a new cell. For example, the gNB may decide to execute a cell switch to a target cell and / or it may transmit a Medium Access Control (MAC) Control Element (CE) triggering cell switch by including a candidate configuration index (ID) of the target cell. The apparatus, e.g. the UE, may switch to the target cell and / or apply the configuration indicated by the candidate configuration index. If the apparatus, e.g. the UE, does not already have a valid TA for the target cell, it may perform a random access procedure, e.g. before it can fully connect. Once the apparatus, e.g. the UE switches to the target cell and / or it completes the LTM cell switch procedure, it may transmit a message, in particular a RRCReconfigurationComplete message, to the (new) target cell, in particular to confirm the switch. If the apparatus, e.g. the UE, has performed a Random Access (RA) procedure, the apparatus, e.g. the UE, may consider that LTM cell switch execution is successfully completed, in particular when the Random Access (RA) procedure is successfully completed. For RACH-less LTM, the apparatus, e.g. the UE, may consider that LTM cell switch execution is successfully completed, in particular when the apparatus, e.g. the UE determines that the network has successfully received its first Uplink (UL) data. The steps from the DL synchronization onward may be performed multiple times, e.g. for subsequent LTM using the LTM candidate configuration(s) provided in a preceding step. The procedure may also apply to both intra-gNB-DU and inter-gNB-DU mobility. For intra-gNB-DU LTM, the apparatus, e.g. the UE, may switch between cells within the same Distributed Unit (DU), e.g. under the same gNB. For inter-gNB-DU LTM, the apparatus, e.g. the UE may switch between cells that belong to different DUs, possibly even different gNBs. F1-C interface procedures related to LTM mayhandle signaling and / or mobility management between a CU (Central Unit) and a DU (Distributed Unit).

[0391] As mentioned above, a LTM cell switch decision may be based on L1 measurements, which may be performed and / or reported using L1 measurement reports, for example by the apparatus, e.g. by the UE. Alternatively, a LTM cell switch decision may be based on L3 measurements which may be reported using L3 measurement reports. Measurements and / or reporting may be based on LTM candidate cell configuration provided by the network for one or more LTM candidate cells.

[0392] L1 (Layer 1) measurements may include physical-layer measurements to evaluate radio conditions. These measurements may involve assessing signal strength, quality, and / or other parameters, e.g. of reference signal(s) transmitted by a network node, e.g. using one or more beams. L1 measurements may be used for mobility management, such as handovers, beam management, and / or connection re-establishments. In order to select appropriate candidate cells and / or beams, e.g. for early uplink and / or downlink synchronization and / or cell switching in LTM, both intra-frequency L1 measurements and / or inter-frequency L1 measurements, e.g. using synchronization signal block (SSB) transmissions from the candidate cells, may be supported and / or utilized. Intra-frequency L1 measurements may refer to measurements performed on reference signals, e.g. transmitted on a same carrier frequency as a serving cell, which may be used to, e.g. evaluate the serving cell’s signal quality. Inter-frequency L1 measurements may refer to measurements performed on reference signals, e.g. transmitted on frequencies different from the serving cell’s carrier frequency, which may be used to, e.g. evaluate the signal quality of cells or beams operating on different frequency layers. Reference Signals used for L1 measurements may include Synchronization Signal Blocks (SSBs). Layer 3 (L3) measurements may be used to provide higher-layer mobility management functions and / or may assist in determining whether a cell is a viable candidate for mobility, e.g. by monitoring Reference Signals (RS), such as SSB-based signals. For example, L3 measurements may correspond to L1 measurements that may be filtered at Layer 3, e.g. to remove or minimize an impact of, e.g. fast fading, in particular to reduce short term variations in measurement results.

[0393] A "mobility or cell configuration" (these terms may be used interchangeably herein) may be regarded as a set of network parameters, e.g. provided to the apparatus, e.g. the UE, to guidehow it should perform mobility procedure(s) and / or to define how and / or when the apparatus, e.g. the UE, should trigger one or more mobility-related action(s). The mobility configuration may be associated with at least one candidate / target cell. A mobility configuration may include at least one of: at least one Channel State Information, CSI, resource configuration and / or at least one CSI reporting configuration. The mobility configuration may also include at least one offset value. In an example, the mobility configuration may be a L1 / L2 Triggered Mobility, LTM, configuration or LTM (candidate) cell configuration. In the exemplary context of LTM, the mobility configuration may be included in a message. This may be for example, referred to as a "LTM Configuration message", which may be understood as at least one message, e.g. from a network node, to configure an apparatus, e.g. a User Equipment (UE), for one or more parts or steps of a LTM process and / or a LMT procedure, for example a LTM cell change / switch. The LTM message may comprise data, information, configurations, parameters and / or instructions, in particular as exemplarily outlined above, e.g. for the UE, e.g. to perform and / or trigger mobility-related measurements and / or reporting.

[0394] A "candidate cell" (or "target cell") (these terms may be used interchangeably herein) may be referred to as a neighboring cell or one of UE’s current serving cell (e.g. SCell) that the apparatus, e.g. the UE, evaluates as a potential replacement for the current serving cell (e.g. PCell or PSCell), in particular during a mobility event. If particular conditions are met / satisfied, the UE may initiate a transition process to the target cell. The "serving cell" may be the active cell currently providing network connectivity to the UE. The UE may, in particular continuously, measure a quality of the serving cell and compare it with potential candidate cell(s) to determine if a mobility event is required. LTM candidate cell(s) may be neighboring cell(s) or a UE’s current serving cells (e.g. SCells) (as mentioned above). LTM measurements on a candidate cell may performed using SSBs transmitted by the candidate cell for which the SSB configuration is provided to the UE.

[0395] As mentioned above, another type of mobility procedure may be a handover procedure, which may be based on Layer 3 (L3) measurements, which the UE may report to the network. In particular, a handover procedure may be considered a mobility procedure where the network controls the transition of a UE, e.g. from a serving cell to a target cell. It may be considered a higher-layer (e.g. Layer 3 (L3), RRC-controlled) procedure / process. Based on the reported measurements, the network may decide to command the UE to hand over to another cell, e.g. through RRC command.Mobility procedures, such as LTM cell changes and / or handovers, may be subjected to and / or have associated delays, which will be exemplarily introduced / described in the following:

[0396] For example, a handover procedure may have associated handover delay(s) and / or requirement(s), which may be taken from TS 38.133. For example, a baseline L3 handover delay may start from the apparatus, e.g. the UE, receiving a Radio Resource Control (RRC) handover command and it may end at the apparatus, e.g. the UE, sending a Random Access Channel (RACH) preamble to the target cell.

[0397] The (handover) delay may comprise one or more of the following parameters:

[0398] TRRC = a RRC processing delay of the handover command;

[0399] Tsearch = a time required to search the target cell, e.g. if the target cell is unknown. (A cell may be considered known, if it has been meeting a relevant cell identification requirement, s. for example clause 9.2.5 for intra-frequency handover and / or clause 9.3.4 for inter-frequency handover in TS 38.133) during the last 5 seconds; otherwise it may be considered to be unknown.)

[0400] Tprocessing = a time for UE processing related to handover execution;

[0401] Tdeita = a time for fine time tracking and / or acquiring full timing information of the target cell based on at least one Synchronization Signal Block (SSB);

[0402] Tmargin = a time for SSB processing, which may be equal to about 2 ms, and / or

[0403] Tiu = a time for interruption uncertainty, e.g. in acquiring a first available PRACH occasion in the target cell. The value can be e.g. about 20 ms.A handover interruption may comprise all parameters of the handover delay, for example except TRRC. Interruption may be regarded as a time within which the apparatus, e.g. the UE, is not expected to be able to receive and / or transmit data, resources, signals, information etc.

[0404] As mentioned above, another type of mobility procedure may be cell change, transition and / or switch procedure (these terms may be used interchangeably herein) referred to as Lower Layer- or Layer 1 (L1) / Layer2 (L2) triggered mobility (LTM in short). For example, the network may configure, e.g. up to 8, candidate cell(s) in particular through RRC for the apparatus, e.g. the UE, and may send an, in particular Medium Access Control (MAC)-Control Element (CE), cell switch command, which may be used to request / command the apparatus, e.g. the UE, to change cell to one of these candidate cell(s). This can be based on UE’s reported L1 (e.g. FR1 and FR2) or L3 (e.g. FR1 only) measurements. Before sending the cell switch command, the network may have an option to activate one or more configured Transmission Configuration Index (TCI) state(s), e.g. for one or more of the candidate cell(s), through an, in particular MAC-CE, TCI state activation command. This may be to enable the apparatus, e.g. the UE, to perform (fine) DL synchronization, e.g. before the cell switch, for example to reduce the interruption time by removing the (fine) DL synchronization (in particular Tdeita and / or Tmargin) from the cell switch delay.

[0405] Additionally, the network may have the option to configure the apparatus, e.g. the UE, to perform early UL synchronization, in particular either through a PDCCH ordered RACH procedure or through UE based TA estimation. Through PDCCH ordered RACH or UE based TA estimation, the cell switch delay can be reduced even more, in particular by moving the UL synchronization (TIU) partially outside of the delay.

[0406] Additionally, at least if the UE supports the capability for early ASN.1 decoding and / or validity check, it may perform this step before the cell switch, in particular either when receiving the LTM RRC configuration or at the time of receiving a TCI state activation command or a PDCCH order. The requirements for TLTM_RRC-processing may be taken from section 6.3 of TS 38.133, which are provided below.

[0407] A (LTM) cell switch delay may be i) without one or more of early UL and DL synchronization or early ASN.1 decoding or ii) with early UL and DL synchronization and early ASN.1 decoding. In the latter case ii) the cell switch interruption may be shortened, in particular due to performingone or more of the three mentioned steps before the cell switch. It should be noted that PDCCH ordered RACH may cause an interruption to the serving cell based on UE capability.

[0408] The (LTM) switch delay may comprise one or more of the following parameters:

[0409] Tcmd = MAC-CE processing delay + HARQ ACK delay: THARQ + 3ms;

[0410] TLTM_RRcProcessing = Time for ASN.1 decoding and / or validity / compliance check for the RRC configuration of the LTM target cell. Value may be 0 ms, in particular if done before cell switch command, otherwise it may be about 10 ms;

[0411] Tfirst-Rs = a time for fine time tracking and / or acquiring full timing information of the target cell. It may refer to a time until the first SSB, e.g. if DL synchronization is not done before the cell switch, otherwise it may be 0 ms;

[0412] TRs-Proc= a time for SSB processing. The value may be about 2 ms, e.g. if DL synchronization is not done before the cell switch, otherwise it may be 0 ms;

[0413] TLTM_Processing = a time for apparatus / UE processing, in particular

[0414] including applying the target cell parameters and

[0415] L1 / L2 change. The value may be between 10-40 ms, in particular depending on the frequency range of the source and target cell and UE capability, e.g. to support faster UE processing;

[0416] TLTM-IU = an interruption uncertainty during LTM cell switch.

[0417] For a RACH-based LTM cell switch, TLTM-IU may be the interruption uncertainty in acquiring the first available PRACH occasion in the new cell. TLTM-IU may be up to the summation of SSB to PRACH occasion association period and may be about 10 ms. SSB to PRACH occasion associated period may be taken from table 8.1-1 of TS 38.213.For a RACH-less LTM cell switch, TLTM-IU may be the uncertainty on transmitting the first uplink transmission on the target cell.

[0418] "Uplink (UL) synchronization" may refer to a process where the apparatus, e.g. the UE, aligns its transmission timing with the network's expectations, e.g. to ensure proper communication. In other words, the apparatus, e.g. the UE, may transmit its signals at a correct timing, e.g. so they reach the network without collisions or interference. "Downlink (DL) synchronization" may refer to a process where the apparatus, e.g. the UE, aligns itself with timing and / or frequency of a downlink signal from the network. DL synchronization may ensure that the apparatus, e.g. the UE, can correctly receive and / or interpret signals from the network. "Early" synchronization may refer to initiating and / or performing at least one of: UL or DL synchronization, in particular before the actual execution of a cell switch / change procedure. Early synchronization may prepare the apparatus, e.g. the UE, fora transition / switch / change. "Configuration processing" may refer to how the apparatus, e.g. the UE, may process and / or apply network / cell configuration(s), including interpreting, decoding network instructions such as protocol messages that, e.g., describe how communication should be established or adjusted. Configuration processing may allow the apparatus, e.g. the UE, to understand and / or apply network instructions, in particular dynamically, to e.g. ensure smooth operation. A non-limiting example of configuration processing may be Abstract Syntax Notation One (ASN.1) decoding. ASN.1 may be a standard, e.g. platform-independent, data format used to define, encode, transmit, and / or decode structured data. ASN.1 decoding may thus refer to a process of interpreting and / or extracting information from ASN.1-encoded messages, e.g. received from the network.

[0419] A "command" or "synchronization command" as described herein may be regarded as a new (type of) command and / or a new signaling. The synchronization command may also be referred to as an "early synchronization (sync) command", as it may be received before at least one of: reception of a cell change command, or execution of a cell change procedure as described herein. The command may be understood as an order, instruction, indication and / or message, e.g. received by the apparatus, e.g. the UE, and / or transmitted by, e.g. a cell, in particular a serving cell of a network. The command may provide instructions to perform (or at least to cause performance / performing of) UL and Downlink DL synchronization with at least one cell.The command may be an explicit command, e.g. including all necessary information / instructions for execution, e.g. the command may be explicitly readable by the apparatus, e.g. the UE, so that the information / instructions may be directly taken therefrom, e.g. from at least one Information Element (IE) etc. However, the command may be an implicit command, e.g. including only minimal information / instructions, which may require the apparatus, e.g. the UE, to infer / derive additional details / information and / or to perform further actions to conclude to the, e.g. full set of, instructions. In case of an implicit command, data or information for determining or deriving the instructions to perform UL / DL synchronization may be provided, e.g. in / as an Information Element (IE), e.g. embedded in the command. For example, the command may "provide" instructions to perform UL and DL synchronization, which may be understood as i) including (explicit) instructions to perform UL and DL synchronization, in particular directly embedded in the command, or ii) (implicit) instructions, e.g. requiring the apparatus, e.g. the UE, to derive / infer the instructions to perform UL and DL synchronization from the command.

[0420] The command may provide instructions to perform Uplink (UL) and Downlink (DL) synchronization with at least one cell, in particular for / to perform both UL and DL synchronization with at least one cell. The command may cause, initiate, trigger and / or induce, in particular both, UL synchronization and DL synchronization to be performed and / or to be at least initiated. In non-limiting example, the synchronization command may be at least one of: an in-band protocol header, a Medium Access Control (MAC) Control Element (CE) command or an Abstract Syntax Notation One (ASN.1) message. The command may include further instructions, in particular in addition to the instructions for UL synchronization and DL synchronization with the at least one cell. For example, the synchronization command may provide instructions to perform cell configuration processing of at least one cell configuration. The command as described herein may reduce signaling overhead and / or reduce a number of commands used / required for signaling, e.g. in / for mobility procedures and / or reduce interruption time(s), e.g. related to cell change procedures. Also, signaling may be simplified.

[0421] The synchronization command as described herein is a "single" command. For example, the synchronization command may be a single, singular, standalone, discrete and / or independent indication, unit or message. A single command may mean that multiple actions, such as initiation / performance of UL / DL synchronization, are combined into one command and / or that it the command does not require additional messages to be send in order to instruct thesemultiple actions. It may include all necessary details to perform the respective actions and / or correspond to an all-in-one message / indication, in particular with respect to causing both UL synchronization and DL synchronization to be performed. The instructions to perform (or at least cause performance / performing of; which may be used interchangeable herein) UL synchronization and DL synchronization may be combined, merged, united, joined, consolidated, unified, bundled, linked and / or brought together in the synchronization command, in particular the same (single) synchronization command. The above features may reduce signaling overhead, improve resource efficiency / utilization, and / or it may reduce a number of commands used / required for signaling, e.g. in / for mobility procedures.

[0422] According to subject-matter described herein, the synchronization command (and / or the instructions to perform Uplink (UL) and Downlink (DL) synchronization) may be received and / or processed before occurrence of at least one time delay associated to a cell change procedure of the apparatus. The at least one time delay may include at least one of: i) a processing delay (e.g. Tcmd), for example a MAC-CE processing delay and / or ii) an acknowledgement delay, for example a Hybrid Automatic Repeat Request (HARQ) acknowledgment (ACK) delay; iii) a delay for configuration processing, for example Abstract Syntax Notation One (ASN.1) decoding; iv) a delay for (e.g. fine) time tracking and / or acquiring (e.g. full) timing information of the at least one cell, for example a time until a first reference signal, e.g. an Synchronization Signal Block (SSB); v) a delay for processing of at least one Reference Signal (RS), for example a SSB; vi) a processing delay for target cell configuration(s) processing and / or validity / compliance checking, or vii) a delay associated with a Random Access (RA) procedure, or viii) a delay associated with waiting for UL resources for transmission on the target cell. The command may be received "before" any of the above delays i)-viii), which may be understood that both instructions to cause UL / DL synchronization are received and / or processed before anyone of the above delays i)-viii) occurs / starts. This may assist in reducing signaling overhead and / or simplifying signaling.

[0423] The apparatus, e.g. the UE, may optionally inform / indicate to the network, about, in particular successfully, completion of synchronization, e.g. UL synchronization and DL synchronization. The indication may be, as described above, an explicit indication or an implicit indication. The indication may be included in or correspond to a UL and DL synchronization complete message, e.g. on the at least one cell. The indication may also be included in or correspond to at least one preamble transmission, e.g. on the at least one cell. This may allow the networkto confirm that the apparatus, e.g. the UE, is ready for further communication or transition to a new cell. This may allow the network, e.g. to proceed with scheduling data transmission, HARQ responses, finalizing a cell transition etc. If the apparatus, e.g. the UE, does not (explicitly) signal synchronization completion, the network might assume the apparatus, e.g. the UE, is still in progress, e.g. leading to missed scheduling opportunities and / or inefficient resource allocation. The indication may be included in or correspond to at least one of: an Abstract Syntax Notation One (ASN.1) message, a control header, ora Layer 2 (L2) message, e.g. on the at least one, in particular candidate, cell. Alternatively, a maximum delay for the apparatus, e.g. the UE, to complete the early synchronization may be predefined, for example in standard. After this delay, the network may assume the apparatus, e.g. the UE, has completed the early synchronization.

[0424] The "cell change command" as described herein may be regarded as a new command and / or a new type of cell change command and / or a new signaling. The at least one cell change command may include at least one indication. The at least one indication may indicate that execution of the cell change procedure to the at least one cell is to be delayed or delayable. The at least one indication may indicate that execution and / or initiation of the cell change procedure is delayed, in particular by at least one, e.g. pre-defined, time period, time slot, time window and / or time frame, e.g. a time delay period. The delay may be expressed in an absolute time, e.g. in Milliseconds [ms] or the like. The at least one indication may be an explicit indication, e.g. directly readable from the at least one cell change command. The apparatus, e.g. the UE, may not be required to compute, derive and / or conclude to the delay in such a case, e.g. as it may be clearly defined therein. The cell change command may also correspond to a new type of command and / or it itself may correspond to an indication that may indicate that execution of the cell change procedure to the at least one cell is to be delayed or delayable. For example, the at least one time delay period may be indicated and / or implicitly provided, derived, inferred and / or deduced from a particular type of the cell change command. The apparatus, e.g. the UE, may recognize the delay, e.g. from the command type itself. As such, the cell change command may correspond to an implicit indication regarding, e.g. the time delay period. This may assist in improving signaling overhead, reduction of interruption times and / or improve utilization of signaling resources.

[0425] The apparatus, e.g. the UE, may optionally inform / indicate to the network, about its ability to perform one or more of UL synchronization, DL synchronization, and cell configurationprocessing (e.g., ASN.1 decoding) without interrupting its connection to the current serving cell. This indication can be sent either when the cell change procedure starts or even before the apparatus, e.g. the UE, receives a formal cell change command, apparatus, e.g. the UE, may optionally transmit at least one indication to the network that indicates which steps of UL synchronization, DL synchronization or cell configuration processing decoding are performable without causing an interruption to the at least one serving cell. In other words, the steps which are performable uninterruptedly, free of interruption(s), without interruption(s), continuously and / or non-stop. In addition or alternatively, the apparatus, e.g. the UE, may not only inform / indicate to the network which steps can be done without interruption, but it may also provide an estimate of how much time may be required to complete a particular steps. For example, the apparatus, e.g. the UE, may transmit at least one indication to the network that indicates at least one time period required to perform at least one step of: UL synchronization, DL synchronization or cell configuration processing without causing an interruption to the at least one serving cell. As mentioned, the apparatus, e.g. the UE, may transmit this indication for example when the cell change procedure begins (e.g. after the transition is decided) or, for example, before receiving the cell change command (e.g. before the network even makes a decision about the transition). This may allow the network to factor in the UE’s capability in advance, e.g. when deciding on the transition. If the network knows that certain steps (e.g., UL sync, DL sync) can be performed without interrupting the serving cell connection, it can schedule the transition more smoothly. By knowing in advance how long certain processes take, the network can better plan resource allocation and / or scheduling. If the network receives this indication before issuing a cell change command, it can proactively select a better timing for the change, e.g. leading to smoother transitions.

[0426] The aforementioned example may provide even greater flexibility, e.g. by having offset values mapped to specific RS pairs or sets based on QCL and / or TCI associations.

[0427] The term "non-transitory," as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0428] As used herein, "at least one of the following: " and "at least one of " and similar wording, where the list of two or more elements are joined by "and" or "or", mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.The apparatus may include a processor configured to provide signals to and receive signals and to control the functioning of the apparatus. The processor may be configured to control other elements of apparatus by effecting control signaling via electrical leads connecting processor to the other elements, such as a display or a memory. The processor may, for example, be embodied in a variety of ways including circuitry, at least one processing core, one or more microprocessors with accompanying digital signal processor(s), one or more processor(s) without an accompanying digital signal processor, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements including integrated circuits (for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), and / or the like), or some combination thereof.

[0429] The term "circuitry" may refer to one or more or all of the following:

[0430] (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and

[0431] (b) combinations of hardware circuits and software, such as (as applicable):

[0432] (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and

[0433] (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

[0434] hardware circuit(s) and / or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0435] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.The apparatus may comprise memory which may store information elements. The apparatus may include volatile memory and / or non-volatile memory. For example, volatile memory may include Random Access Memory (RAM) including dynamic and / or static RAM, on-chip or off-chip cache memory, and / or the like. Non-volatile memory, which may be embedded and / or removable, may include, for example, read-only memory, flash memory, magnetic storage devices, for example, hard disks, floppy disk drives, magnetic tape, optical disc drives and / or media, non-volatile random access memory (NVRAM), and / or the like. Like volatile memory, non-volatile memory may include a cache area for temporary storage of data. At least part of the volatile and / or non-volatile memory may be embedded in processor. The memories may store one or more software programs, instructions, pieces of information, data, and / or the like which may be used by the apparatus for performing operations disclosed herein.

[0436] The apparatus may be a User Equipment (UE), for example a mobile or handled device, for example a mobile phone or a smart phone, or may be at least comprised in a UE.

[0437] Fig. 1a shows an example signaling with example delays according to subject-matter described herein. It should be noted that any reference related to specific features such as LTM / HO, and / or recitation of particular / associated delays, or the like, may be considered optional and / or not limiting. In particular, Fig. 1a illustrates subject-matter which may be applied to mobility procedures, e.g. to a handover procedure and / or a LTM procedure. Fig. 1a will be described in connection with Fig. 1b, which shows an example signaling according to subject-matter described herein.

[0438] Step 1: The network may send a mobility configuration or a cell configuration, in particular a RRC reconfiguration with one or more candidate cell(s) for handover / cell switch. The RRC configuration may include, for example cell specific configuration parameters, including a measurement configuration and / or reporting configuration, TCI state information, including candidate TCI states, and other cell information of the candidate cell(s). This configuration can be considered as the pre-configuration of the candidates, and it may also include candidate cell measurement configurations. This mobility configuration is not expected to cause interruption for the serving cell(s). In the example of LTM, this may be called a LTM mobility configuration and / or a LTM candidate cell configuration. It should be noted that step 1 may be optional.Step 2: The network may send a (single) synchronization command (cf. Early UL / DL Sync command in Fig. 1a), in particular a combined DL / UL synchronization command. For example, the network may indicate early DL and UL synchronization in the same, combined, early sync command (which is a new type of command). The command may include a TCI state activation command / instruction and an instruction to cause initiation of a Random Access (RA) procedure for UL synchronization, for example a PDCCH order, or another similar information for the apparatus, e.g. the UE, to be able to perform DL synchronization and / or preamble transmission, e.g. to the target candidate cell. Additionally, the UE may be required to perform configuration processing, e.g. early ASN.1 decoding and / or validity check and / or any other step(s) of the cell switch based on the synchronization command. The synchronization command may be an in-band protocol header, e.g. a MAC-CE command, or the synchronization command be a ASN.1 message, e.g. transmitted by the lower layers (e.g. L2 / MAC). The synchronization command may activate one or more TCI state(s) and / or it may orderthe apparatus, e.g. the UE, to perform at least one (e.g. RACH) preamble transmission, in particular on at least one candidate cell.

[0439] Step 3: Based on the received synchronization command or DL / UL sync command, the apparatus, e.g. the UE, may perform (fine) DL synchronization with the target candidate cell and / or it may send a preamble to the target candidate cell, in particular for TA acquisition purposes. The apparatus, e.g. the UE, may also perform other step(s) related to cell switch preparation, e.g. depending on apparatus, e.g. UE, capability and / or -requirements.

[0440] Optionally, the apparatus, e.g. the UE, may inform the / indicate to the network about completion of the preparation actions / procedure related to the received synchronization command or DL / UL sync command, in particular by transmitting an indication, e.g. which may be included in or correspond to a UL and DL synchronization complete message, in particular on the at least one cell (cf. UE indication about UL / DL sync completion in Fig. 1a). The indication may be included in or correspond to at least one of: an Abstract Syntax Notation One (ASN.1) message, a control header, or a Layer 2 (L2) message on the at least one cell. Alternatively, this point may be known to the network, e.g. through standardized apparatus, e.g. UE, requirements, -capability, and / or a, in particular network signaled, timer.

[0441] Step 4: The synchronization command or the early DL / UL sync command can be followed by a handover / cell switch command (cf. cell switch / HO command in Fig. 1a). The cell switch command can be for example a MAC-CE as in LTM, or it may be ASN.1 message, or in-bandsignal, in particular transmitted by the same protocol entity as the previous synchronization command. In other words, the apparatus, e.g. the UE, may receive a cell switch command to the same cell the synchronization command or the DL / UL sync was performed based on step 2.

[0442] Step 5: The apparatus, e.g. the UE, may perform a cell switch, in particular with a delay that does not comprise / is free of / lacks delay(s), e.g. related to any step that was performed based on the DL / UL sync command in step 2.

[0443] In another example related to Figs. 1a and / or 1b, the sequence of actions may be similar as depicted in Fig. 1b, but instead of performing RACH transmission, the apparatus, e.g. the UE, may perform apparatus-, e.g. UE-, based TA estimation. The apparatus-, e.g. UE-, based TA estimation may be initiated, started and / or triggered by the synchronization command. The apparatus-, e.g. UE-, based TA estimation may be indicated in the synchronization command, or the apparatus, e.g. the UE, may use a candidate reference, e.g. to derive the configuration from the RRC configuration configured in step 1 of the signaling diagram shown in Fig. 1b.

[0444] In the signaling depicted in Fig. 1b (and 1a) and / or one or more of the associated examples mentioned in connection therewith, the number of commands corresponds to 3 (e.g. RRC, synchronization command and cell switch command) which is less than a number of commands typically required for other cell switch procedures (e.g. LTM where typically 4 commands are required). To this end, the number of commands and / or in particular signaling overhead may be reduced based on at least one signaling as described herein. In addition, interruption duration, for example in LTM, e.g. where the apparatus, e.g. the UE, supports early UL / DL synchronization may be reduced.

[0445] Fig. 2a shows an example signaling with example delays according to subject-matter described herein. It should be noted that any reference related to specific features such as LTM / HO, and / or recitation of particular / associated delays, or the like, may be considered optional and / or not limiting. In particular, Fig. 2a illustrates subject-matter which may be applied to mobility procedures, e.g. to a handover procedure and / or a LTM procedure. Fig. 2a will be described in connection with Fig. 2b, which shows an example signaling according to subject-matter described herein.Step 1 : The network may send a mobility configuration or a cell configuration, in particular a RRC reconfiguration with one or more candidate cell(s) for handover / cell switch (cf. Candidate cell RRC configuration in Fig. 2a). The RRC configuration may include, for example cell specific configuration parameters, including a measurement configuration and / or reporting configuration, TCI state information, including candidate TCI states, and other cell information of the candidate cell(s). This configuration can be considered as the pre-configuration of the candidates, and it may also include candidate cell measurement configurations. This mobility configuration is not expected to cause interruption for the serving cell(s). In the example of LTM, this may be called a LTM mobility configuration and / or a LTM candidate cell configuration. It should be noted that step 1 may be optional. The apparatus, e.g. the UE, may avoid / delay performing DL synchronization and / or UL synchronization, e.g. before receiving the cell switch command, but, for example, it may perform configuration processing, e.g. early ASN.1 decoding, in particular based on the RRC configuration.

[0446] Step 2: The network may send a (new type of) cell change command (cf. HO / cell switch command in Fig. 2a) to the apparatus, e.g. the UE, to switch / change the connection to at least one of the candidate cell(s). The decision to send the cell change command may be done by the network, e.g. based on reported UE measurements. The cell change command may include a target TCI state. The apparatus, e.g. the UE, may know, e.g. based on the cell change command, that it is allowed and / or expected to delay the cell change execution for UL / DL synchronization purposes. To indicate this, the cell change command may include at least one indication about this behavior, or it may be a specific type of cell change command, which may implicitly mean / indicate that the apparatus, e.g. the UE, shall act accordingly. The cell switch command can be for example a message, in particular a Medium Access Control (MAC) Control Element (CE) message, e.g. as in LTM, a Radio Resource Control (RRC) message or RRC reconfiguration message and / or a configuration processing message, in particular a ASN.1 message. The cell switch command can be for example transmitted by at least one of the lower layers, e.g. from Layer 2 (L2) or Layer (L3) etc.

[0447] Step 3: The apparatus, e.g. the UE, may perform at least one of: UL synchronization, Downlink DL synchronization, or cell configuration processing, in particular ASN.1 decoding and / or validity checking based on the cell switch command (or any other step (one or more) of the cell switch the apparatus, e.g. the UE, may perform without causing an interruption). In particular, before executing the cell switch (e.g. before the interruption starts), the apparatus, e.g. the UE,may perform at least one of: configuration processing, e.g. ASN.1 decoding and / or validity check, (fine) DL synchronization and UL synchronization, in particular either based on RACH preamble transmission or UE based TA estimation (or some of these steps), e.g. according to the RRC configuration or based on the cell switch command. The apparatus, e.g. the UE, may keep the connection to the source cell and / or may monitor for any possible scheduling messages from the network. During this time the apparatus, e.g. the UE, can be scheduled / is schedulable and / or remains schedulable / schedulability (these terms may be used interchangeably herein) (cf. Fig. 2a). Depending on UE capability, if RACH preamble transmission is used to acquire the TA, this may cause an interruption, but the location of the interruption may not necessarily be predefined, so the network may continue to schedule the UE, and the interruption may happen at some point during scheduling.

[0448] Step 4: Optionally, the apparatus, e.g. the UE, may transmit at least one indication to the network that indicates completion of the preparation actions in step 3, e.g. at least one of: UL synchronization, DL synchronization or cell configuration processing. Alternatively, in one example, this may be known to the network, e.g. through standardized UE requirements, UE capability and / or a, in particular network signaled, timer. For example and / or optionally, the UE may send an indication to the source cell, e.g. at the moment it starts cell switch execution (e.g. interruption), in particular to inform the source cell that the preparation steps are now completed. For example and / or optionally, the UE may send an indication to the network, e.g. after it has completed pre-defined step, or after a predefined time, e.g. "X" ms / slots prior to the start of the interruption. In another example, a (maximum) time the UE is allowed to delay the cell switch execution may be defined. Such a timer can be configured, for example by the network or be predefined in the standard. The duration of the timer may be adjusted to the time it is expected for the UE to complete the preparation steps. At the expiration of the timer, the UE may execute the cell switch, in particular regardless of whether the preparation steps are completed or not.

[0449] Step 5: After the apparatus, e.g. the UE, has completed all the steps that it can or the steps it may be required to compete before the cell switch execution, the apparatus, e.g. the UE, may execute the cell switch and interruption may begin (cf. Fig. 2a). In an example, if TA is available at this point (e.g. due to UL synchronization being performed), the cell switch may be RACH-less. Otherwise, e.g. if the preparation died not comprise UL synchronization, the cell switch may be RACH-based.In the signaling depicted in Fig. 2b (and 2a) and / or one or more of the associated examples mentioned in connection therewith, the number of commands corresponds to 2 (e.g. RRC, cell switch command) which is less than a number of commands typically required for other cell switch procedures. To this end, the number of commands and / or in particular signaling overhead may be reduced based on at least one signaling as described herein. In addition, interruption duration, for example in LTM, e.g. where the apparatus, e.g. the UE, supports early UL / DL synchronization may be reduced.

[0450] Fig. 3a shows an example signaling with example delays according to subject-matter described herein. It should be noted that any reference related to specific features such as LTM / HO, and / or recitation of particular / associated delays, or the like, may be considered optional and / or not limiting. In particular, Fig. 3a illustrates subject-matter which may be applied to mobility procedures, e.g. to a handover procedure and / or a LTM procedure. Fig. 3a will be described in connection with Fig. 3b, which shows an example signaling according to subject-matter described herein.

[0451] Figs. 3a / 3b may be considered similar / related to Figs. 2a / 2b and / or be combined therewith. In particular, steps / features disclosed in connection with Figs. 2a / 2b above, may be applicable or correspondingly applicable to Figs. 3a / 3b. For example, in the example shown in Figs. 3a / 3b, the network may not send a candidate cell configuration before the cell switch command, which may be regarded similar to a L3 handover. However, the network may configure measurements for neighboring cells of the UE separately before the cell switch command, but the full, or necessary target cell configuration may be, for example, sent in the cell switch or handover command, which may be, e.g., an ASN.1 message, or RRC command. Hence, in this example, the apparatus, e.g. the UE, may not perform configuration processing, e.g. early ASN.1 decoding, DL sync or UL sync before the cell switch command.

[0452] Step 1: The network may send a (new type of) cell change command (cf. HO / cell switch command in Fig. 3a) to the apparatus, e.g. the UE, to command it to switch / change the connection to at least one of the candidate cell (s) or to handover to at least one candidate cell. The decision to send the cell change command may be done by the network, e.g. based on reported UE measurements, which may be performed and / or reported by the apparatus, e.g. the UE, for example based on an earlier network configuration. The cell change command mayinclude a target TCI state. The apparatus, e.g. the UE, may know, e.g. based on the cell change command, that it is allowed and / or expected to delay the cell change execution for UL / DL synchronization purposes. To indicate this, the cell change command may include at least one indication about this behavior, or it may be a specific type of cell change command, which may implicitly mean / indicate that the apparatus, e.g. the UE, shall act accordingly. The cell switch command can be for example a message, in particular a Medium Access Control (MAC) Control Element (CE) message, e.g. as in LTM, a Radio Resource Control (RRC) message or RRC reconfiguration message and / or a configuration processing message, in particular a ASN.1 message. The cell switch command can be for example transmitted by at least one of the lower layers, e.g. from Layer 2 (L2) or Layer (L3) etc.

[0453] Step 2: Similar to the approach depicted in Figs. 2a / 2b, the apparatus, e.g. the UE, may perform at least one of: UL synchronization, Downlink DL synchronization, or cell configuration processing, in particular ASN.1 decoding and / or validity checking based on the cell change command (or any other step (one or more) of the cell change the apparatus, e.g. the UE, may perform without causing an interruption). In particular, before executing the cell change (e.g. before the interruption starts), the apparatus, e.g. the UE, may perform at least one of: configuration processing, e.g. ASN.1 decoding and / or validity check, (fine) DL synchronization and UL synchronization, in particular either based on RACH preamble transmission or UE based TA estimation (or some of these steps), e.g. according to the RRC configuration or based on the cell change command. The apparatus, e.g. the UE, may keep the connection to the source cell and / or may monitor for any possible scheduling messages from the network. During this time the apparatus, e.g. the UE, can be scheduled / is schedulable (cf. Fig. 3a). Depending on UE capability, if RACH preamble transmission is used to acquire the TA, this may cause an interruption, but the location of the interruption may not necessarily be predefined, so the network may continue to schedule the UE.

[0454] Step 3: Optionally, the apparatus, e.g. the UE, may transmit at least one indication to the network that indicates completion of the preparation actions in step 3, e.g. at least one of: UL synchronization, DL synchronization or cell configuration processing. Alternatively, in one example, this may be known to the network, e.g. through standardized UE requirements, UE capability and / or a, in particular network signaled, timer. Furthermore and optionally, the UE may send an indication to the source cell, e.g. at the moment it starts cell change execution (e.g. interruption), in particular to inform the source cell that the preparation steps are nowcompleted. For example and / or optionally, a (maximum) time the UE is allowed to delay the cell change execution may be predefined or configured as described.

[0455] Step 4: After the apparatus, e.g. the UE, has completed all the steps that it can or the steps it may be required to compete before the cell change execution, the apparatus, e.g. the UE, may execute the cell change and interruption may begin (cf. Fig. 3a). In an example, if TA is available at this point (e.g. due to UL synchronization being performed), the cell change may be RACH-less. Otherwise, e.g. if the preparation died not comprise UL synchronization, the cell change may be RACH-based.

[0456] In the signaling depicted in Fig. 3b (and 3a) and / or one or more of the associated examples mentioned in connection therewith, the number of commands corresponds to 1 (e.g. cell change command) which is less than a number of commands typically required for other cell switch procedures. To this end, the number of commands and / or in particular signaling overhead may be reduced based on at least one signaling as described herein. In addition, interruption duration, for example in LTM, e.g. where the apparatus, e.g. the UE, supports early UL / DL synchronization may be reduced.

[0457] It should be noted that in the approach depicted in Figs. 3a / 3b, the apparatus, e.g. the UE, may be able to perform some configuration processing, e.g. ASN.1 decoding, DL synchronization and UL synchronization, in particular without causing an interruption. The steps the apparatus, e.g. the UE, performs without interruption may be informed / indicated to the network, e.g. through one or more UE capabilities. Additionally, for example, if the apparatus, e.g. the UE, does not send an indication about when it has completed the non-interruption steps, the apparatus, e.g. the UE, may inform the network, e.g. as a UE capability, about a time it takes to perform the non-interruption steps, in particular after receiving the cell change / HO command. This time may be informed for example in milliseconds [ms] or Reference Signal (RS) periodicity / -ies. Alternatively, for example, the time may be defined in the standards, e.g. as a delay during which the apparatus, e.g. the UE, shall be able to be scheduled / schedulable. In an example, if all the three steps may not be expected to be performed without interruption, this requirement may comprise only the steps that are expected to be performed without interruption, and other steps may be counted / defined / regarded as part of the cell switch / handover interruption.Figs. 4a / 4b show an example signaling according to subject-matter described herein. It should be noted that any reference related to specific features such as LTM / HO or the like, may be considered optional and / or not limiting. In particular, Figs. 4a / 4b illustrate subject-matter which may be applied to mobility procedures, e.g. to a handover procedure and / or a LTM procedure.

[0458] In the approach depicted in Figs. 4a / 4b, interruption reduction after receiving a handover or cell switch command may be done by the apparatus / UE implementation, which may be considered similar to the approach shown in Figs. 2a / 2b and / or 3a / 3b, where the apparatus, e.g. the UE, may receive a handover RRC command, or cell switch command, in particular possibly following an optional RRC candidate cell configuration. The apparatus, e.g. the UE, may perform the cell change steps it can perform without causing an interruption, e.g. before performing the steps that cause an interruption. The apparatus, e.g. the UE, behavior may be the same as Figs. 2a / 2b and / or 3a / 3b, in particular the apparatus, e.g. the UE, may continue to be connected to the source cell, for example, until it has completed the non-interruption steps. This means that the network may not aware of when the interruption begins, in particular at the apparatus-, e.g. the UE-, side and / or the UE requirement may still be based on the assumption that the interruption starts after the cell change command. The Network may choose to continue schedule the apparatus, e.g. the UE, in particular after sending the cell change command, but the apparatus, e.g. the UE, may not be required to be available for scheduling. The apparatus, e.g. the UE, may continue to be scheduled and / or the network can continue to schedule the apparatus, e.g. the UE, in particular until it does not receive a HARQ response. If the network does not receive a HARQ response from the apparatus, e.g. the UE, it may know or regard this as an indication to stop the scheduling.

[0459] The following signaling diagram shown in Figs. 4a / 4b depict the apparatus, e.g. the UE, and the network actions in this approach. As mentioned above, an LTM-like cell switch is used as a non-limiting example here, but the same behavior may apply to other mobility procedures, such as an, e.g. RRC-based (and / or, e.g. L3, Handover-like) handover.

[0460] Step 1 : The network may send a mobility configuration or a cell configuration, in particular a RRC reconfiguration with one or more candidate cell(s) for handover / cell switch. The RRC configuration may include, for example cell specific configuration parameters, including a measurement configuration and / or reporting configuration, TCI state information, including candidate TCI states, and other cell information of the candidate cell(s). This configuration canbe considered as the pre-configuration of the candidates, and it may also include candidate cell measurement configurations In the example of LTM, this is also called LTM candidate cell configuration.

[0461] Step 2: The network may send a cell change command to the apparatus, e.g. the UE, to switch / change the connection to at least one of the candidate cell(s). The decision to send the cell change command may be done by the network, e.g. based on reported UE measurements.

[0462] Step 3: The apparatus, e.g. the UE, may decide and / or determine to keep the connection to the source cell and / or it may perform at least one of UL synchronization, Downlink DL synchronization, or cell configuration processing, in particular ASN.1 decoding and / or validity checking based on the cell switch command (or any other step (one or more) of the cell switch the apparatus, e.g. the UE, may perform without causing an interruption). The apparatus, e.g. the UE, may monitor for any possible scheduling messages from the network. The apparatus, e.g. the UE, may send HARQ responses accordingly. In particular, the apparatus- / UE-behavior regarding scheduling may continue similar as before receiving the cell switch command.

[0463] Step 4: As the behavior of step 3 may not be required from the UE based on standardized requirements in this approach, the network may not know whether a UE is acting according to step 3 or not. The network may continue to schedule the UE after sending the cell switch command, and if the UE responds with HARQ, the network may know / be indicated that the UE received the scheduling message(s). When the UE does not respond to the scheduling message(s), e.g. with HARQ, the network may know / be indicated the UE has started the interruption.

[0464] Step 5: After the UE has completed all the steps that it can complete before cell switch execution, the UE may execute the cell switch and interruption begins. After this point the UE may no longer monitor any scheduling (messages) from the source cell, which is visible to the network, e.g. through a missing HARQ response, in particular if the network tries to schedule the UE.

[0465] Fig. 5 shows a flow chart 500 of an example aspect of subject-matter described herein. The flow chart may comprise steps of an apparatus, a method and / or a non-transitory computer readable medium as mentioned herein.The flow chart 500 may include the step of receiving 510 a synchronization command from a serving cell, wherein the synchronization command provides instructions to perform Uplink (UL) and Downlink (DL) synchronization with at least one cell,. The flow chart 500 may include the step of initiating 520 UL synchronization and DL synchronization with the at least one cell based at least in part on the synchronization command.

[0466] The flow chart 500 may comprise or be combined with one or more additional steps associated with some of the example aspects and / or associate example embodiments described herein.

[0467] Fig. 6 shows a flow chart 600 of an example aspect of subject-matter described herein. The flow chart may comprise steps of an apparatus, a method and / or a non-transitory computer readable medium as mentioned herein.

[0468] The flow chart 600 may include the step of receiving 610 at least one cell change command from at least one serving cell of a network that indicates execution of a cell change procedure to at least one cell of the network. The flow chart 600 may include the step of 620 performing, based at least in part on the at least one cell change command, at least one of: Uplink (UL) synchronization, Downlink (DL) synchronization, or cell configuration processing for the at least one cell while maintaining a connection to the at least one serving cell. The flow chart 600 may include the step of monitoring 630 for at least one scheduling message from the network until execution of the cell change procedure.

[0469] The flow chart 600 may comprise or be combined with one or more additional steps associated with some of the example aspects and / or associate example embodiments described herein.

[0470] While the foregoing is directed to embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.LIST OF ABBREVIATIONS

[0471] ACK Acknowledgment

[0472] ASN.1 Abstract Syntax Notation One BFD Beam Failure Detection

[0473] CE Control Element

[0474] CSI Channel State Information

[0475] DC Dual Connectivity

[0476] DL Downlink

[0477] HARQ Hybrid Automatic Repeat reQuest HO Handover

[0478] III Interruption Uncertainty

[0479] L1 Layer 1

[0480] L2 Layer 2

[0481] L3 Layer 3

[0482] LTM L1 / L2 Triggered Mobility

[0483] MAC Medium Access Control

[0484] MCG Master Cell Group

[0485] NG Next Generation

[0486] PCell Primary Cell

[0487] PBCH Physical Broadcast Channel PCI Physical Cell Identity

[0488] PDCCH Physical Downlink Control Channel PDSCH Physical Data Shared Channel PSCell Primary Secondary Cell

[0489] RA Random Access

[0490] RACH Random Access Channel

[0491] RAN Radio Access Network

[0492] RRC Radio Resource Control

[0493] RS Reference Signal

[0494] RSRP Reference Signal Received Power SCG Secondary Cell Group

[0495] SCell Secondary Cell

[0496] SI NR Signal to Interference Noise RatioSS Synchronization Signal

[0497] SSB Synchronization Signal Block TA Timing Advance

[0498] TCI Transmission Configuration Index UE User Equipment

[0499] UL Uplink

[0500] LIST OF REFERENCE NUMERALS

[0501] 400-500 Flowchart

[0502] 510, 610 Receiving step

[0503] 520 Initiating step

[0504] 620 Performing step

[0505] 630 Monitoring step

Claims

74CLAIMS1. Apparatus, comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:receiving a synchronization command from a serving cell, wherein the synchronization command provides instructions to perform Uplink (UL) and Downlink (DL) synchronization with at least one cell,initiating UL synchronization and DL synchronization with the at least one cell based at least in part on the synchronization command.

2. Apparatus according to claim 1 , wherein the synchronization command provides instructions to perform cell configuration processing of at least one cell configuration.

3. Apparatus according to any one of the preceding claims, wherein the synchronization command is an early synchronization command which is received before at least one of:- reception of a cell change command, or- execution of a cell change procedure.

4. Apparatus according to any one of the preceding claims, wherein the synchronization command is a single command.

5. Apparatus according to any one of the preceding claims, wherein the synchronization command corresponds to or is included in a single message.

6. Apparatus according to any one of the preceding claims, wherein the synchronization command is received and / or processed before occurrence of at least one time delay associated to a cell change procedure of the apparatus, wherein the at least one time delay includes at least one of:- a processing delay,- an acknowledgement delay,- a delay for acquiring timing information of the at least one cell,75- a delay for processing of at least one Reference Signal (RS), including a Synchronization Signal Block (SSB),- a processing delay for target cell configuration processing and validity checking, or - a delay associated with a Random Access (RA) procedure.

7. Apparatus according to any one of the preceding claims, wherein the instructions to perform UL synchronization and DL synchronization are merged or bundled together in the synchronization command.

8. Apparatus according to any one of the preceding claims, wherein the instructions to perform UL synchronization and DL synchronization include at least one Transmission Configuration Indicator (TCI) state activation instruction.

9. Apparatus according to any one of the preceding claims, wherein the synchronization command is at least one of: an in-band protocol header, a Medium Access Control (MAC) Control Element (CE) command or an Abstract Syntax Notation One (ASN.1) message.

10. Apparatus according to any one of the preceding claims, wherein the synchronization command is transmitted by at least one lower layer, wherein the synchronization command is transmitted by a Layer 2 (L2) or a MAC layer.

11. Apparatus according to any one of the preceding claims, wherein the UL and DL synchronization is performed for a cell change procedure to the at least one cell, wherein the cell change procedure is a Layer 3 (L3) cell change procedure.

12. Apparatus according to any one of the preceding claims, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:receiving at least one cell configuration of the at least one cell from the at least one serving cell.

13. Apparatus according to claim 12, wherein the at least one cell configuration is a Radio Resource Control (RRC) configuration of the at least one cell, wherein the at least one cell configuration is received before reception of the synchronization command.7614. Apparatus according to any one of the preceding claims 12-13, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:performing cell configuration processing of the at least one cell configuration, based at least in part on the synchronization command,wherein cell configuration processing is performed in addition to UL and DL synchronization.

15. Apparatus according to any one of the preceding claims 12-14, wherein the at least one cell configuration includes at least one of:- at least one measurement configuration,- at least one reporting configuration,- at least one TCI state information, orof the at least one cell.

16. Apparatus according to any one of the preceding claims 8-15, wherein the at least one TCI state activation instruction activates at least one TCI state of the at least one cell.

17. Apparatus according to any one of the preceding claims, wherein the instructions to perform UL synchronization and DL synchronization include an instruction to cause initiation of a Random Access (RA) procedure for UL synchronization.

18. Apparatus according to any one of the preceding claims, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:transmitting a Random Access Channel (RACH) preamble for UL synchronization with the at least one cell based at least in part on the synchronization command.

19. Apparatus according to any one of the preceding claims 1-16, wherein the instructions to perform UL synchronization and DL synchronization include at least one indication to initiate Timing Advance (TA) estimation for UL synchronization.7720. Apparatus according to any one of the preceding claims 1-16 or 19, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:performing Timing Advance (TA) estimation for the at least one cell based at least in part on the synchronization command.

21. Apparatus according to any one of the preceding claims, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:receiving at least one cell change command from the serving cell after performing UL and DL synchronization.

22. Apparatus according to claim 21 , wherein the at least one cell change command is received from a same entity as the synchronization command.

23. Apparatus according to any one of the preceding claims, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:initiating a cell change procedure based on the initiated UL and DL synchronization with the at least one cell.

24. Apparatus according to claim 23, wherein the cell change procedure is a RACH-less cell change procedure, wherein the cell change procedure is free of at least one delay associated with or included in at least one of: UL synchronization, DL synchronization, or cell configuration processing.

25. Apparatus according to any one of the preceding claims, wherein the at least one processor; and the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:transmitting an indication to a network that indicates completion of UL and DL synchronization.7826. Apparatus according to claim 25, wherein the indication is included in or corresponds to a UL and DL synchronization complete message on the at least one cell.

27. Apparatus according to any one of the preceding claims 25-26, wherein the indication is included in or corresponds to at least one preamble transmission on the at least one cell.

28. Apparatus according to any one of the preceding claims 25-26, wherein the indication is included in or corresponds to at least one of:- an Abstract Syntax Notation One (ASN.1) message,- a control header, or- a Layer 2 (L2) messageon the at least one cell.

29. Apparatus according to any one of the preceding claims, wherein the at least one cell is a candidate cell of a network.

30. Apparatus according to any one of the preceding claims 2-29, wherein cell configuration processing includes Abstract Syntax Notation One (ASN.1) decoding.

31. Apparatus according to any one of the preceding claims, wherein the apparatus is a User equipment (UE) or wherein the apparatus is comprised in a UE.

32. Method, comprising:receiving a synchronization command from a serving cell, wherein the synchronization command provides instructions to perform Uplink (UL) and Downlink (DL) synchronization with at least one cell,initiating UL synchronization and DL synchronization with the at least one cell based at least in part on the synchronization command.7933. A non-transitory computer readable storage medium comprising program instructions that, when executed by an apparatus, in particular according to any one of claims 1-31, causes operations comprising:receiving a synchronization command from a serving cell, wherein the synchronization command provides instructions to perform Uplink (UL) and Downlink (DL) synchronization with at least one cell,initiating UL synchronization and DL synchronization with the at least one cell based at least in part on the synchronization command.

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