Handover in dual connectivity to primary base station and secondary base station

Abstract

To provide apparatuses and methods for implementing techniques for user equipment (UE) having dual connectivity.SOLUTION: A wireless communication system comprises UE that communicates with a first primary base station in a first primary cell (PCell) and a second primary base station in a second PCell. The UE has dual connectivity in the second PCell using a first wireless carrier to communicate with the second primary base station and a second wireless carrier to communicate with a secondary base station in a primary secondary cell (PSCell). The UE receives a message from the first primary base station to perform a handover procedure, performs the handover procedure according to the received message, and further performs an addition procedure for the secondary base station in parallel with the handover procedure. A start time of the addition procedure is before end time of the handover procedure.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The aspects to be described generally relate to handovers of user equipment (UE) having dual connectivity to a primary base station and a secondary base station.

Background Art

[0002] Wireless mobile communication technologies use various standards and protocols to transmit data between a base station and a wireless mobile device or user equipment (UE). Wireless communication system standards and protocols can include the 3rd Generation Partnership Project (3GPP (registered trademark)) Long Term Evolution (LTE) standard, the 5th Generation (5G) 3GPP New Radio (NR) standard, and many other standards and protocols. Dual connectivity (DC) is an important feature that can support a UE having two radio carriers with two different standards and protocols. DC can increase per-user throughput by improving the utilization of radio resources across two base stations connected via a backhaul and operating on different carrier frequencies. Also, DC can improve mobility performance. However, DC requires efficient mobility and cell management.

Summary of the Invention

[0003] Some aspects of the present disclosure relate to apparatuses and methods for implementing techniques for providing solutions for handovers of user equipment (UE) having dual connectivity to a primary base station and a secondary base station. The techniques to be implemented may be applicable to many wireless systems, such as wireless communication systems based on 3rd Generation Partnership Project (3GPP) Release 15 (Rel-15), Release 16 (Rel-16), Release 17 (Rel-17), or others.

[0004] Some aspects of the present disclosure relate to a User Equipment (UE). The UE can include a transceiver and a processor communicatively coupled to the transceiver. The transceiver can be configured to enable wireless communication with a first primary base station in a first Primary Cell (PCell) and a second primary base station in a second PCell. The UE can have dual connectivity in the second PCell, using a first radio carrier to communicate with the second primary base station and a second radio carrier to communicate with a secondary base station in a Primary Secondary Cell (PSCell). The processor of the UE is configured to receive, from the first primary base station, a message for executing a handover procedure to hand over the UE from the first primary base station to the second primary base station, and to further execute the handover procedure according to the received message. Further, the processor is configured to execute additional procedures for the secondary base station in parallel with the handover procedure. The start time of the additional procedures can be before the end time of the handover procedure. Further, the processor is configured to use the transceiver to send a first Random Access Channel (RACH) preamble to the second primary base station at a first time instance and a second RACH preamble to the secondary base station at a second time instance.

[0005] In some examples, the first time instance is after the end time of the handover procedure and the second time instance is after the end time of the additional procedures. In some examples, the start time of the additional procedures is the same time instance as the start time of the handover procedure. In some embodiments, the first time instance is independent of the second time instance. Additionally and alternatively, the second time instance is after the first time instance.

[0006] In some examples, the processor is further configured to send an indication to the first primary base station that the UE has the ability to perform handover procedures and additional procedures in parallel. The processor may be configured to perform other operations, for example, to perform change procedures for the UE to change to a secondary base station. Additionally, the processor may be configured to obtain a RACH occasion for transmitting a second RACH preamble to the secondary base station before transmitting the second RACH preamble to the secondary base station. Further, the processor may be configured to receive a random access response (RAR) message from the second primary base station at a third time instance in response to the first RACH preamble transmitted to the second primary base station at a first time instance. The second time instance can be after the third time instance which is after the first time instance. Further, the processor can be configured to schedule an uplink transmission to the second primary base station for contention-based RACH (CBRA) after the third time instance and receive an acknowledgment from the second primary base station at a fourth time instance. The second time instance can be after the fourth time instance.

[0007] Some aspects of the present disclosure relate to a method performed by a UE. The UE communicates with a first primary base station within a first PCell and communicates with a second primary base station within a second PCell. In addition, the UE has dual connectivity in the second PCell, where the UE uses a first radio carrier to communicate with the second primary base station and uses a second radio carrier to communicate with a secondary base station in a primary secondary cell (PSCell). The method includes receiving, from the first primary base station, a message for performing a handover procedure to hand over the UE from the first primary base station to the second primary base station, and performing the handover procedure according to the received message. Further, the method includes, in parallel with the handover procedure, performing an additional procedure for the secondary base station, where a start time of the additional procedure is before an end time of the handover procedure. Further, the method includes sending a first RACH preamble to the second primary base station at a first time instance and sending a second RACH preamble to the secondary base station at a second time instance. The first time instance is after the end time of the handover procedure, and the second time instance is after the end time of the additional procedure.

[0008] Some aspects of the present disclosure relate to a non-transitory computer-readable medium storing instructions. When the instructions stored on the non-transitory computer-readable medium are executed by a processor of a UE, they cause the UE to perform various operations. The UE communicates with a first primary base station within a first PCell and communicates with a second primary base station within a second PCell. Additionally, the UE has dual connectivity in the second PCell where it uses a first radio carrier to communicate with the second primary base station and uses a second radio carrier to communicate with a secondary base station in a primary secondary cell (PSCell). The operations include receiving, from the first primary base station, a message for executing a handover procedure to hand over the UE from the first primary base station to the second primary base station, and executing the handover procedure according to the received message. Further, the operations include, in parallel with the handover procedure, executing an additional procedure for the secondary base station, where a start time of the additional procedure is before an end time of the handover procedure. Still further, the operations include sending a first RACH preamble to the second primary base station at a first time instance and sending a second RACH preamble to the secondary base station at a second time instance. The first time instance is after the end time of the handover procedure, and the second time instance is after the end time of the additional procedure.

[0009] The summary of the invention is provided merely for the purpose of exemplifying some aspects to provide an understanding of the subject matter described herein. Accordingly, the above features are merely examples and should not be construed as narrowing the scope or spirit of the subject matter in the present disclosure. Other features, aspects, and advantages of the present disclosure will become apparent from the following detailed description, drawings, and claims of the invention.

Brief Description of the Drawings

[0010] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate the present disclosure and, together with the description, serve to explain the principles of the present disclosure and further serve to enable one of ordinary skill in the art to make and use the present disclosure.

[0011]

Figure 1

[0012]

Figure 2

[0013]

Figure 3

[0014]

Figure 4A

Figure 4B

Figure 4C

Figure 4D

[0015]

Figure 5

[0016] The present disclosure is described with reference to the accompanying drawings. In the drawings, generally, like reference numerals denote the same or functionally similar elements. Additionally, generally, the leftmost digit(s) of a reference numeral identify the drawing in which the reference numeral first appears.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Embodiments herein present an exemplary solution for a user equipment (UE) having dual connectivity (DC) to perform handover of the UE to a primary base station and a secondary base station. When a UE in a wireless communication system moves from one location to another, the UE can be served by different base stations, e.g., a first base station, a second base station, a primary base station, a secondary base station, or combinations thereof. The procedure when the UE exits a cell managed by a first base station and enters a cell managed by a second base station can be called a handover procedure for handing over the UE from the first base station to the second base station.

[0018] Embodiments of this specification present exemplary handover procedures for a UE having DC. Various DCs can exist. For example, there can be dual connectivity of evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access (E-UTRA) and New Radio (NR) (EN-DC), dual connectivity of NR and E-UTRA (NE-DC), dual connectivity of NR and NR (NR-DC), or dual connectivity of other DCs. Embodiments of this specification are applicable to any dual connectivity known to those skilled in the art.

[0019] First, the UE can communicate with a first primary base station in a first primary cell (PCell). The UE may or may not have dual connectivity in the first PCell. The UE can move out of the first PCell and into a second PCell, and the UE can use a first radio carrier to communicate with the second primary base station and a second radio carrier to communicate with a secondary base station to have dual connectivity in the second PCell. The secondary base station can be within a primary secondary cell (PSCell). In some embodiments, the PCell can refer to the primary base station within the PCell, and the PSCell can refer to the secondary base station within the PSCell.

[0020] According to some aspects, a UE can receive instructions for performing a handover procedure from a first primary base station in a first PCell. The instructions can be carried by a Radio Resource Control (RRC) message. Based on the received instructions, the UE can perform a handover procedure to hand over the UE from the first primary base station to a second primary base station. Additionally, even if the instructions can include only instructions for performing the handover procedure, the UE can perform additional procedures for a secondary base station in parallel with the handover procedure without further instructions from the first primary base station. Details of the handover procedure and the additional procedures will be described later. The start time of the additional procedures is before the end time of the handover procedure. Thereby, the terminal can perform operations for two procedures, for example, the handover procedure and the additional procedures, with one handover instruction. Further, the handover procedure and the additional procedures can be performed in parallel. Therefore, the efficiency of the handover of the UE from a first PCell having dual connectivity to a second PCell can be improved. This additional procedure is only an example. The UE can perform other procedures, for example, modification procedures, in parallel with the handover procedure.

[0021] FIG. 1 shows a wireless communication system 100 including a user equipment (UE) having dual connectivity, for example, UE101, for performing handover of the UE to a primary base station and a secondary base station according to some aspects of the present disclosure. The wireless communication system 100 is provided for illustrative purposes only and does not limit the disclosed aspects.

[0022] According to some aspects, the wireless communication system 100 may include, but is not limited to, a UE 101, a base station (BS) 103, a base station 105, and a base station 107 communicatively connected to a core network 111. The base station 103 manages cell 102, the base station 105 manages cell 104, and the base station 107 manages cell 106. In some examples, the base station 103 may be a first primary base station, and the cell 102 may be a first PCell. The base station 105 may be a second primary base station, and the cell 104 may be a second PCell. The base station 107 may be a secondary base station, and the cell 106 may be a PSCell. In some other examples, the primary base station may be referred to by other names known to those skilled in the art.

[0023] First, the UE 101 can communicate with a base station 103 that may be a first primary base station within cell 102. When the UE 101 moves along direction X, the UE 101 can use a first radio carrier 108 to communicate with a base station 105 that may be a second primary base station and a second radio carrier 109 to communicate with a base station 107 that may be a secondary base station to establish dual connectivity within cell 104. To establish dual connectivity for the UE 101 in cell 104, the UE 101 may execute a handover procedure to communicate with the base station 105 to replace the base station 103. Additionally, additional procedures may be executed so that the UE 101 can communicate with the base station 107. When the UE 101 continues to move along the X direction and exits the cell 106 covered by the base station 107 and enters the coverage area of another secondary base station, change procedures may be executed so that the UE 101 can stop communicating with the base station 107 and start communicating with another secondary base station.

[0024] In some examples, the wireless communication system 100 can be a wireless system that includes dual connectivity with two different radio technologies, such as NR, LTE, 5G, any other radio technology, or combinations thereof. Although many examples are described herein in the context of NR or LTE technologies, the wireless communication system 100 is not limited to such technologies. Instead, the wireless communication system 100 can be any communication system that can perform handovers of a UE to a primary base station and a secondary base station for a UE having dual connectivity. The wireless communication system 100 can include other network entities, not shown but understood by those skilled in the art, such as a network controller, a relay station. The wireless communication system 100 can support a wide range of use cases, such as enhanced mobile broadband (eMBB), massive machine type communications (mMTC), ultra-reliable and low-latency communications (URLLC), and enhanced vehicle to anything communications (eV2X).

[0025] According to some aspects, base stations 103, 105, and 107 can be fixed stations or mobile stations. Base stations 103, 105, and 107 may be referred to by other names such as a base transceiver system (BTS), an access point (AP), a transmit / receive point (TRP), an evolved Node B (eNB), a next-generation Node B or a new radio Node B (gNB), a next-generation evolved Node B (ng-eNB), a 5G Node B (NB), or other equivalent terms understood by those skilled in the art. In some examples, base stations 103, 105, and 107 can be interconnected with each other and / or with other base stations or network nodes in the network through various types of backhaul interfaces such as direct physical connections, wireless connections, virtual networks, etc.

[0026] According to some aspects, UE 101 can be fixed or mobile. UE 101 can be a cellular phone (e.g., a smartphone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop, a desktop, a cordless phone, a wireless local loop station, a tablet, a camera, a gaming device, a netbook, an ultrabook, a medical device or instrument, a biosensor or device, a wearable device (smart jewelry such as a smartwatch, smart clothing, smart glasses, smart wristband, smart ring, or smart bracelet), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicle component, a smart meter, industrial manufacturing equipment, a global positioning system device, an Internet of Things (IoT) device, a machine type communication (MTC) device, an evolved or enhanced machine type communication (eMTC) device, or any other suitable device configured to communicate via a wireless medium. For example, MTC and eMTC devices can include robots, drones, location tags, etc.

[0027] According to some aspects, within cell 102, UE 101 can be served by New Radio (NR) Standalone (SA), Long Term Evolution (LTE), E-UTRA and New Radio DC (EN-DC), New Radio-E-UTRA DC (NE-DC), or New Radio DC (NR-DC).

[0028] According to some aspects, UE 101 can establish dual connectivity in cell 104 by using a first radio carrier 108 to communicate with base station 105 and a second radio carrier 109 to communicate with base station 107. The dual connectivity for UE 101 within cell 104 can be EN-DC, NE-DC, NR-DC, or any other DC known to those skilled in the art. Thus, the first radio carrier 108 can operate using LTE, NR, E-UTRA, or any other radio technology, and the second radio carrier 109 can operate using LTE, NR, E-UTRA, or any other radio technology. The handover from base station 103 within cell 102 to the DC within cell 104 can be a handover from NR SA to EN-DC, a handover from EN-DC to EN-DC, a handover from NE-DC to NE-DC, a handover from NR-DC to NR-DC, or some other DC handover.

[0029] According to some aspects, the UE 101 can receive a message 113 from the base station 105 to execute a handover procedure for handing over the UE 101 from the base station 103 to the base station 103. In some examples, the command can be carried by an RRC message. According to the message 113, the UE 101 can execute a handover procedure for handing over the UE 101 from the base station 103 to the base station 105 and execute additional procedures for the base station 107 in parallel with the handover procedure. The start time of the additional procedures can be before the end time of the handover procedure. For example, the start time of the additional procedures can be the same time instance as the start time of the handover procedure. Further, the UE 101 can send an indication to the base station 103 to indicate that the UE 101 has the ability to perform the handover procedure and the additional procedures in parallel. In some examples, the indication can be further configured as a per-UE indication, a per-band combination (BC) indication, or a per-band BC indication. Details of the handover procedure and the additional procedures will be described later. After the handover is completed, the UE 101 can further execute a change procedure for changing the UE 101 from the base station 107 to another base station while maintaining DC with the base station 105.

[0030] In some examples, the handover procedure performed by the UE 101 can include one or more of the following operations: automatic gain control (AGC) setting of the second PCell, downlink cell synchronization of the second PCell, time / frequency (T / F) tracking for the second PCell, software processing or radio frequency (RF) warm-up, synchronization signal block (SSB) processing, or primary synchronization signal (PSS) / secondary synchronization signal (SSS) detection, or some other operations.

[0031] In some examples, the additional procedures for the base station 107 can include one or more operations of AGC setting of the PSCell, downlink cell synchronization of the PSCell, T / F tracking for the PSCell, software processing or RF warm-up, SSB processing, or PSS / SSS detection.

[0032] According to some aspects, the UE 101 can send a first random access channel (RACH) preamble 115 to the base station 107 at a first time instance and send a second RACH preamble 117 to the base station 105 at a second time instance. The RACH is a procedure by which the UE 101 desires to establish an initial connection with the base station. In some examples, the UE 101 can obtain a RACH occasion for sending the second RACH preamble 117 to the base station 107 before sending the second RACH preamble 117. In some examples, the first time instance is after the end time of the handover procedure, and the second time instance is after the end time of the additional procedure. In some embodiments, the first time instance can be independent of the second time instance. In some other examples, the second time instance can be after the first time instance.

[0033] According to some aspects, the UE 101 can further receive a random access response (RAR) message from the base station 105 at a third time instance in response to the first RACH preamble 115 transmitted to the base station 105 at the first time instance. In some examples, the second time instance is after the third time instance which is after the first time instance.

[0034] According to some aspects, the UE 101 can further schedule an uplink transmission to the base station 105 for contention-based RACH (CBRA) after the third time instance, and can receive an acknowledgement from the base station 105 at a fourth time instance where the second time instance is after the fourth time instance.

[0035] According to some aspects, UE 101 can be implemented according to the block diagram as shown in FIG. 2. UE 101 can have an antenna panel 217 coupled to transceiver 203 and including one or more antenna elements for forming various antenna beams, such as beam 219, controlled by processor 209. Specifically, transceiver 203 can include a radio frequency (RF) circuit 216, a transmission circuit 212, and a reception circuit 214. RF circuit 216 can include a number of parallel RF chains for one or more of the transmission function or the reception function, each of which is connected to one or more antenna elements of the antenna panel. In addition, processor 209 can be communicatively coupled to memory device 201, and memory device 201 is further coupled to transceiver 203. Various data can be stored in memory device 201. In some examples, memory device 201 can store message 113, first RACH preamble 115, and second RACH preamble 117 described above. Memory device 201 can include instructions that, when executed by processor 209, perform handover procedures and additional procedure related functions described herein. Alternatively, processor 209 can be "hard coded" to perform location related functions described herein.

[0036] FIG. 3 shows an exemplary method 300 performed by a UE having dual connectivity to perform handover of the UE to a primary base station and a secondary base station, according to some aspects of the present disclosure. Method 300 can be performed (or controlled) by processor 209 in cooperation with other components of UE 101. More specifically, processor 209 can execute instructions stored in memory 201 to perform the operations described below for UE 101, or processor 209 can be "hard coded" to perform the operations described below for UE 101.

[0037] In 301, the UE 101 can receive, from the first primary base station, a message for executing a handover procedure to hand over the UE from the first primary base station to the second primary base station. The UE 101 communicates with the first primary base station on the first PCell and communicates with the second primary base station on the second PCell. The UE 101 has dual connectivity in the second PCell, using the first radio carrier to communicate with the second primary base station and using the second radio carrier to communicate with the secondary base station within the PSCell. For example, the UE 101 can receive, in the first PCell, e.g., cell 102, an RRC message, e.g., message 113, from the base station 103. According to message 113, the UE 101 executes a handover procedure to hand over the UE 101 from the first primary base station, e.g., the base station 103 within cell 102, to the second primary base station, e.g., the base station 105 within cell 104. The UE 101 has dual connectivity in the second PCell, e.g., cell 104, using the first radio carrier 108 to communicate with the base station 105 and using the second radio carrier 109 to communicate with the base station 107.

[0038] In 303, the UE 101 can execute a handover procedure to hand over the UE 101 from the first primary base station to the second primary base station. For example, the UE 101 can execute a handover procedure to hand over the UE 101 from the base station 103 to the base station 105.

[0039] In 305, the UE 101 can execute, in parallel with the handover procedure, an additional procedure for a secondary base station, where the start time of the additional procedure is before the end time of the handover procedure. For example, the UE 101 can execute, in parallel with the handover procedure, an additional procedure for the base station 107. The start time of the additional procedure can be before the end time of the handover procedure.

[0040] At 307, UE 101 can send a first RACH preamble to a second primary base station at a first time instance that is after the end time of the handover procedure. For example, UE 101 can send a first RACH preamble 115 to a second primary base station, e.g., base station 105, at a first time instance that is after the end time of the handover procedure.

[0041] At 309, UE 101 can transmit a second RACH preamble to a secondary base station at a second time instance that is after the end time of the additional procedure. For example, UE 101 can send a second RACH preamble 117 to a secondary base station, e.g., base station 107, at the second time instance.

[0042] Figures 4A - 4D show exemplary methods, e.g., method 410, method 420, method 430, and method 440, performed by a UE 101 having dual connectivity to perform handover of the UE to a primary base station and a secondary base station, according to some aspects of the present disclosure. Method 410, method 420, method 430, and method 440 can be performed by a processor 209 of UE 101 as described above. Method 410, method 420, method 430, and method 440 are all examples of method 300 shown in FIG. 3 with different implementation details.

[0043] Method 410 is shown in FIG. 4A. FIG. 4A shows operations performed along two parallel timelines, a PSCell addition timeline showing operations performed for a secondary base station and a PCell handover timeline showing operations performed for handover of UE 101 from a first primary base station to a second primary base station. The operations are marked to be performed at various time instances.

[0044] At time instance T411, UE101 can perform operations to receive an RRC message containing a command for executing a handover procedure. The operations performed at 411 can be similar to the operations performed at 301 of method 300 shown in FIG. 3.

[0045] At time instance T412, UE101 has completed the processing of the RRC message. The time delay between time instances T411 and T412 is shown as T RRC-手順-遅延 which is long enough for UE101 to complete the processing of the RRC message and identify a command or instruction for executing the handover procedure. In some examples, T RRC-手順-遅延 can also include a period for waiting for a RACH occasion.

[0046] At time instance T412, at 413, UE101 can start a handover procedure to hand over UE101 to the target PCell, for example, to hand over UE101 from base station 103 to base station 105. The operations performed at 413 can be similar to the operations performed at 303 shown in FIG. 3.

[0047] At time instance T412, at 415, the addition of the target PSCell is started. For example, operations for the addition procedure to base station 107 can be performed so that base station 107 can serve UE101. The operations performed at 415 can be similar to the operations performed at 305 shown in FIG. 3. FIG. 4A shows that the operations at 413 and the operations at 415 are performed simultaneously. In some other examples, they can have different start times. For example, the operations at 415 for the addition procedure can start after the start of the handover operation at 413.

[0048] At time instance T413, the operation for adding the target PSCell is completed. The time gap between time instance T412 and time instance T413 is T add-PSCell as shown, which includes at least the time for completing the target PSCell addition procedure. At the same time, at 419, UE101 can send a RACH preamble to the target PSCell. For example, UE101 can send the second RACH preamble 117 to base station 107. The operation executed at 419 can be similar to the operation executed at 309 shown in FIG. 3.

[0049] At time instance T414, the operation for the handover procedure to hand over UE101 to the target PCell is completed. The time gap between time instance T412 and time instance T414 is T 割込み as shown. At the same time, at 417, UE101 can send a RACH preamble to the target PCell. For example, UE101 can send the first RACH preamble 115 to base station 105. The operation executed at 417 can be similar to the operation executed at 307 shown in FIG. 3.

[0050] As shown in FIG. 4A, the operation at 419 for sending a RACH preamble to the target PSCell and the operation at 417 for sending a RACH preamble to the target PCell are executed independently without restrictions on the time order between the two events. As shown in FIG. 4A, the operation at 419 is executed at time instance T413 earlier than time instance T414. In some other embodiments, the operation at 419 can be executed after time instance T414 at which the operation at 417 is executed.

[0051] As shown in FIG. 4A, the total time used to complete the operations shown in FIG. 4A is T ハンドオーバ+追加 =T RRC-手順-遅延 +max{T割込み , T add-PSCell can be shown as {T}. RRC-手順-遅延 is the RRC message processing time for handover between primary base stations and is the same as the conventional handover time without dual connectivity. 割込み is the time to complete the handover procedure to hand over UE101 to the target PCell, e.g., base station 105. add-PSCell is the time to complete the target PSCell addition procedure, e.g., to execute the addition procedure for base station 107. add-PSCell and 割込み can both include the time to wait for a RACH occasion. add-PSCell can include the time to perform operations such as automatic gain control (AGC) setting of the PSCell, downlink cell synchronization of the PSCell, time / frequency (T / F) tracking for the PSCell, software processing or radio frequency (RF) warm-up, synchronization signal block (SSB) processing, or primary synchronization signal (PSS) / secondary synchronization signal (SSS) detection. Similarly Interrupt can include the time to perform operations such as AGC setting of the second PCell, downlink cell synchronization of the second PCell, T / F tracking for the second PCell, software processing or RF warm-up, SSB processing, or PSS / SSS detection.

[0052] Similar to method 410, method 420 in FIG. 4B shows operations performed along two parallel timelines: a PSCell addition timeline showing operations performed for the secondary base station and a PCell handover timeline showing operations performed for the handover of UE101 from the first primary base station to the second primary base station.

[0053] At time instance T421, at 421, UE101 can perform an operation to receive an RRC message including a command for executing a handover procedure. The operation performed at 421 can be similar to the operation performed at 301 of method 300 shown in FIG. 3. At time instance T422, UE101 RRC-手順-遅延 has completed the processing of the RRC message after a time delay T.

[0054] At time instance T422, at 423, UE101 can start a handover procedure to hand over UE101 to the target PCell, for example, to hand over UE101 from base station 103 to base station 105. The operation performed at 423 can be similar to the operation performed at 303 shown in FIG. 3.

[0055] At time instance T422, at 425, the addition of the target PSCell is started. For example, operations for the addition procedure to base station 107 can be performed so that base station 107 can serve UE101. The operation performed at 425 can be similar to the operation performed at 305 shown in FIG. 3. FIG. 4B shows that the operations at 423 and the operations at 425 are performed simultaneously. In some other examples, they can have different start times. At time instance T423, the operations for the addition of the target PSCell are completed. The time gap between time instance T422 and time instance T423 is shown as T add-PSCell and this includes at least the time for completing the target PSCell addition procedure. At time instance T424, the operations for the handover procedure to hand over UE101 to the target PCell are completed Interrupt after a time gap of T.

[0056] At time instance T424, at 427, UE101 can transmit a RACH preamble to the target PCell. For example, UE101 can send the first RACH preamble 115 to base station 105. The operations performed at 427 can be similar to the operations performed at 307 shown in FIG. 3. UE101 further waits for the time period T for the next available RACH to the PSCell, which is available at time instance T425. RO between.

[0057] At time instance T425, at 429, UE101 can transmit a RACH preamble to the target PSCell. For example, UE101 can send the second RACH preamble 117 to base station 107. The operations performed at 429 can be similar to the operations performed at 309 shown in FIG. 3.

[0058] Furthermore, at time instance T426, at 428, UE101 can receive a random access response (RAR) message from the target PCell in response to the RACH preamble transmitted to the PCell. For example, UE101 can receive an RAR message from base station 105 in response to the first RACH preamble 115 transmitted to base station 105. The time gap between T424 and T426 can be represented as T. msg2 and can be represented as.

[0059] As shown in FIG. 4B, the total time used to complete the operations shown in FIG. 4A can be shown as T ハンドオーバ+追加 = T RRC-手順-遅延 + max{T 割込み , T add-PSCell}+ T RO and can be shown as.

[0060] Similar to method 410, method 430 in FIG. 4C shows operations executed along two parallel timelines: a PSCell addition timeline showing operations executed for a secondary base station, and a PCell handover timeline showing operations executed for the handover of UE101 from a first primary base station to a second primary base station.

[0061] At time instance T431, at 431, UE101 can perform operations to receive an RRC message containing a command for executing a handover procedure. The operations executed at 431 can be similar to the operations executed at 301 of method 300 shown in FIG. 3. At time instance T432, UE101 has completed the processing of the RRC message after a time delay T RRC-手順-遅延 has completed the processing of the RRC message after a time delay T.

[0062] At time instance T432, at 433, UE101 can start a handover procedure to hand over UE101 to the target PCell, for example, to hand over UE101 from base station 103 to base station 105. The operations executed at 433 can be similar to the operations executed at 303 shown in FIG. 3.

[0063] At time instance T432, at 435, the addition of the target PSCell is started. For example, operations for an addition procedure for base station 107 can be executed so that base station 107 can serve UE101. The operations executed at 435 can be similar to the operations executed at 305 shown in FIG. 3. FIG. 4C shows that the operations at 433 and the operations at 435 are executed simultaneously. In some other examples, they can have different start times. At time instance T433, the operations for the addition of the target PSCell are completed. The time gap between time instance T432 and time instance T433 is T add-PSCellis shown as this includes at least the time to complete the target PSCell addition procedure. At time instance T434, the operations for the handover procedure to hand over UE101 to the target PCell are at T Interrupt completed after the time gap of.

[0064] At time instance T434, at 437, UE101 can transmit a RACH preamble to the target PCell. For example, UE101 can send the first RACH preamble 115 to base station 105. The operations executed at 437 can be similar to the operations executed at 307 shown in FIG. 3. Further, at time instance T435, at 438, UE101 can receive a RAR message from the target PCell in response to the RACH preamble transmitted to the PCell. For example, UE101 can receive a RAR message from base station 105 in response to the first RACH preamble 115 transmitted to base station 105. The time gap between time instance T434 and time instance T435 is T msg2 and can be. UE101 further waits during the time period T RO for the next available RACH to the PSCell, which is available at T436.

[0065] At time instance T436, at 439, UE101 can transmit a RACH preamble to the target PSCell. For example, UE101 can send the second RACH preamble 117 to base station 107. The operations executed at 439 can be similar to the operations executed at 309 shown in FIG. 3.

[0066] As shown in FIG. 4C, the total time used to complete the operations shown in FIG. 4A is T ハンドオーバ+追加 = T RRC-手順-遅延 + max{T 割込み + T msg2 , T add-PSCell}+ T RO and can be shown as.

[0067] Similar to method 410, method 440 in FIG. 4D shows operations executed along two parallel timelines: a PSCell addition timeline showing operations executed for a secondary base station and a PCell handover timeline showing operations executed for a handover of UE 101 from a first primary base station to a second primary base station.

[0068] At time instance T441, at 441, UE 101 can perform operations to receive an RRC message containing a command to execute a handover procedure. The operations performed at 441 can be similar to the operations performed at 301 of method 300 shown in FIG. 3. At time instance T442, UE 101 has completed processing the RRC message after a time delay T RRC-手順-遅延 has elapsed.

[0069] At time instance T442, at 443, UE 101 can initiate a handover procedure to hand over UE 101 to a target PCell, for example, to hand over UE 101 from base station 103 to base station 105. The operations performed at 443 can be similar to the operations performed at 303 shown in FIG. 3.

[0070] At time instance T442, at 445, target PSCell addition is initiated. For example, operations for an addition procedure for base station 107 can be performed so that base station 107 can serve UE 101. The operations performed at 445 can be similar to the operations performed at 305 shown in FIG. 3. FIG. 4D shows that the operations at 443 and the operations at 445 are executed simultaneously. In some other examples, they can have different start times. At time instance T443, the operations for target PSCell addition are completed. The time gap between time instance T442 and time instance T443 is T add-PSCellis shown as, which includes at least the time to complete the target PSCell addition procedure. At time instance T444, the operation of the handover procedure to hand over UE101 to the target PCell is at T Interrupt after the time gap of is completed.

[0071] At time instance T444, at 447, UE101 can transmit a RACH preamble to the target PCell. For example, UE101 can send the first RACH preamble 115 to base station 105. The operation executed at 447 can be similar to the operation executed at 307 shown in FIG. 3. Further, at time instance T445, at 448, UE101 can receive a RAR message from the target PCell in response to the RACH preamble transmitted to the PCell. For example, UE101 can receive a RAR message from base station 105 in response to the first RACH preamble 115 transmitted to base station 105. The time gap between time instance T444 and time instance T445 can be T msg2 can be.

[0072] At time instance T446, at 451, UE101 can schedule an uplink transmission to the second primary base station for contention-based RACH (CBRA). At time instance T447, at 453, UE101 can receive an acknowledgement from the second primary base station at the fourth time instance. The time gap between time instance T445 and time instance T447 can be T msg4 can be. After time instance T447, UE101 further waits for the period T RO available for the next available RACH to the PSCell, which is available at T448.

[0073] At time instance T448, at 449, UE 101 can transmit a RACH preamble to the target PSCell. For example, UE 101 can send the second RACH preamble 117 to base station 107. The operations performed at 449 can be similar to the operations performed at 309 shown in FIG. 3.

[0074] As shown in FIG. 4D, the total time used to complete the operations shown in FIG. 4A is T ハンドオーバ+追加 =T RRC-手順-遅延 +max{T 割込み +T msg2 +T msg4 ,T add-PSCell}+T RO and can be shown as.

[0075] Various aspects can be implemented using one or more computer systems, such as computer system 500 shown in FIG. 5 for example. Computer system 500 can be any computer capable of performing the operations described herein, such as UE 101, base station 103, base station 105, base station 107 as shown in FIGS. 1 - 2, and the operations described in FIGS. 3 and 4A - 4D. Computer system 500 includes one or more processors (also called central processing units, i.e., CPUs), such as processor 504. Processor 504 is connected to a communication infrastructure 506 (e.g., a bus). Computer system 500 also includes user input / output devices (singular or plural) 503, such as a monitor, keyboard, pointing device, etc., that communicate with communication infrastructure 506 via user input / output interface(s) 502. Computer system 500 also includes main or primary memory 508, such as random access memory (RAM). Main memory 508 may include one or more levels of cache. Control logic (e.g., computer software) and / or data are stored in main memory 508.

[0076] Computer system 500 may also include one or more secondary storage devices or secondary memory 510. Secondary memory 510 may include, for example, hard disk drive 512 and / or removable storage device or removable storage drive 514. Removable storage drive 514 may be a floppy disk drive, magnetic tape drive, compact disk drive, optical storage device, tape backup device, and / or any other storage device / drive.

[0077] Removable storage drive 514 may interact with removable storage unit 518. Removable storage unit 518 includes a computer-usable or computer-readable storage device in which computer software (control logic) and / or data is stored. Removable storage unit 518 may be a floppy disk, magnetic tape, compact disk, DVD, optical storage disk, and / or any other computer data storage device. Removable storage drive 514 reads from and / or writes to removable storage unit 518 in a well-known manner.

[0078] According to some aspects, the secondary memory 510 may include other means, instrumentalities, or other techniques for enabling a computer system 500 to access a computer program and / or other instructions, and / or data. Examples of such means, instrumentalities, and other techniques may include, for example, a removable storage unit 522 and an interface 520. Examples of the removable storage unit 522 and the interface 520 may include a program cartridge and a cartridge interface (such as those found in video game devices), a removable memory chip (such as an EPROM or PROM) and associated socket, a memory stick and a USB port, a memory card and associated memory card slot, and / or any other removable storage unit and associated interface.

[0079] In some examples, the main memory 508, the removable storage unit 518, and the removable storage unit 522 may store instructions that, when executed by the processor 504, cause the processor 504 to perform operations for a UE or a base station, such as the operations shown in FIGS. 1-2 and described in FIGS. 3 and 4A-4D, for example, operations for a UE such as UE 101, or for a base station such as base stations 103, 105, 107.

[0080] Computer system 500 may further include a communication or network interface 524. The communication interface 524 enables the computer system 500 to communicate with and interact with any combination of remote devices, remote networks, remote entities, etc. (individually and collectively referred to by reference numeral 528). For example, the communication interface 524 may enable the computer system 500 to communicate with a remote device 528 over a communication path 526, which may be wired and / or wireless and may include any combination such as a LAN, WAN, Internet, etc. Control logic and / or data may be transmitted between the computer system 500 via the communication path 526. The operation of the communication interface 524 may be performed by a wireless controller and / or a cellular controller. The cellular controller may be a separate controller for managing communication according to different wireless communication technologies. The operation in the foregoing manner may be implemented in a variety of configurations and architectures. Accordingly, some or all of the operations in the foregoing manner may be performed in hardware, software, or both. In some aspects, a tangible non-transitory device or article of manufacture is herein referred to as a computer program product or program storage device that includes a tangible non-transitory computer-usable or readable medium having control logic (software) stored thereon. This includes, but is not limited to, tangible articles of manufacture embodying the computer system 500, main memory 508, secondary memory 510, removable storage units 518 and 522, and any combination of the foregoing. Such control logic, when executed by one or more data processing devices (such as the computer system 500), causes such data processing devices to operate as described herein.

[0081] Based on the teachings contained in this disclosure, it will be apparent to those of ordinary skill in the relevant technical field(s) how to make and use aspects of this disclosure using data processing devices, computer systems, and / or computer architectures other than those shown in FIG. 5. In particular, aspects can operate in software, hardware, and / or operating system implementations other than those described herein.

[0082] It should be understood that it is the "Detailed Description" section, not the "Summary of the Invention" and "Abstract" sections, that is intended to be used to construe the claims. The summary and abstract paragraphs may describe one or more exemplary aspects of the disclosure, but not all exemplary aspects of the disclosure, as contemplated by the inventor(s). Accordingly, it is not intended that the summary and abstract paragraphs limit the disclosure or the appended claims in any way.

[0083] Although this disclosure is described herein with reference to exemplary aspects for exemplary fields and applications, it should be understood that the disclosure is not limited to the exemplary aspects. Other aspects and variations of the aspects are possible and within the scope and spirit of the disclosure. By way of example, and without limiting the generality of this paragraph, aspects are not limited to software, hardware, firmware, and / or entities shown in the figures and / or described herein. Further, aspects, whether or not explicitly described herein, have significant utility for fields and applications beyond those described in the examples herein.

[0084] Throughout this specification, aspects have been described with the aid of functional building blocks illustrating the implementation of specific functions and their relationships. For the sake of convenience in explanation, the boundaries of these functional building blocks have been arbitrarily defined herein. Alternative boundaries can be defined as long as the specific functions and relationships (or their equivalents) are appropriately implemented. Additionally, alternative aspects may execute functional blocks, steps, operations, methods, etc. using an order different from the order described herein.

[0085] References in this specification to "one embodiment", "an embodiment", "exemplary embodiments", or similar phrases indicate that the described embodiments may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Also, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of those skilled in the relevant art(s) to incorporate such particular feature, structure, or characteristic into other aspects, whether or not explicitly recited or described herein.

[0086] The breadth and scope of the present disclosure should not be limited by any of the above exemplary aspects, but should be defined only in accordance with the following claims and equivalents of the claims.

[0087] In one or more embodiments, for example, at least one of the components described in one or more of the foregoing figures may be configured to perform one or more operations, techniques, processes, and / or methods as described in the following example section. For example, a circuit associated with a thread device, router, network element, etc. described above in connection with one or more of the foregoing figures may be configured to operate in accordance with one or more of the examples described in the following example section.

[0088] The present disclosure contemplates that entities involved in the collection, analysis, disclosure, transmission, storage, or other use of such personal information data will comply with firm privacy policies and / or privacy practices. Specifically, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or government requirements for the strict confidentiality of personal information data. Such policies should be readily accessible to users and should be updated as data collection and / or use changes. Personal information from users should be collected for the legitimate and proper use of the entity and should not be shared or sold except for such legitimate uses. Further, such collection / sharing should only be done after informing the user and obtaining consent. Moreover, such entities should consider taking all necessary measures to protect and secure access to such personal information data and to ensure that others with access rights to personal information data faithfully adhere to their privacy policies and procedures. Additionally, such entities should be able to undergo an evaluation by a third party to demonstrate their compliance with widely accepted privacy policies and practices. Further, the policies and practices should be tailored to the specific types of personal information data being collected and / or accessed and should comply with applicable laws and regulations, including jurisdiction-specific considerations. For example, in the United States, the collection or access to certain health data can be regulated by federal and / or state laws such as the Health Insurance Portability and Accountability Act (HIPAA), while health data in other countries may be subject to different regulations and policies and should be addressed accordingly. Therefore, different privacy practices should be maintained for different types of personal data in each country.

Claims

1. A user equipment (UE), a transceiver configured to enable wireless communication with a first primary base station in a first primary cell (PCell) and a second primary base station in a second PCell, where the UE has dual connectivity in the second PCell using a first wireless carrier to communicate with the second primary base station and a second wireless carrier to communicate with a secondary base station in a primary secondary cell (PSCell); a processor communicatively coupled to the transceiver, the processor comprising: receiving a message from the first primary base station to perform a handover procedure to hand over the UE from the first primary base station to the second primary base station; performing the handover procedure to handover the UE from the first primary base station to the second primary base station; performing an add procedure for the secondary base station in parallel with the handover procedure, where a start time of the add procedure is before an end time of the handover procedure; transmitting, using the transceiver, a first random access channel (RACH) preamble to the second primary base station at a first time instance that is after the end time of the handover procedure; The UE is configured to transmit, using the transceiver, a second RACH preamble to the secondary base station at a second time instance that is after an end time of the additional procedure.

2. The processor, The UE of claim 1 , further configured to: execute a change procedure for changing the secondary base station.

3. The processor, 2. The UE of claim 1, further configured to: obtain a RACH occasion for transmitting the second RACH preamble to the secondary base station prior to transmitting the second RACH preamble to the secondary base station.

4. The UE of claim 1 , wherein the start time of the addition procedure is the same time instance as a start time of the handover procedure.

5. The UE of claim 1 , wherein the first time instance is independent of the second time instance.

6. The UE of claim 1 , wherein the second time instance is after the first time instance.

7. The processor, 2. The UE of claim 1, further configured to receive a Random Access Response (RAR) message from the second primary base station at a third time instance in response to the first RACH preamble transmitted to the second primary base station at the first time instance.

8. The UE of claim 7 , wherein the second time instance is after the third time instance, which is after the first time instance.

9. The processor, scheduling an uplink transmission to the second primary base station for a contention-based RACH (CBRA) after the third time instance; 8. The UE of claim 7, further configured to receive an acknowledgment from the second primary base station at a fourth time instance, the second time instance being after the fourth time instance.

10. The processor, 2. The UE of claim 1, further configured to transmit, using the transceiver, an indication to the first primary base station that the UE has the capability to support the handover procedure and the addition procedure in parallel.

11. 10. The UE of claim 1, wherein the UE is served in the first PCell by Long Term Evolution (LTE), New Radio (NR) Standalone (SA), Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (E-UTRA) and NR Dual Connectivity (EN-DC), NR and E-UTRA Dual Connectivity (NE-DC), or NR and NR Dual Connectivity (NR-DC) technology, and the dual connectivity in the second PCell includes EN-DC, NE-DC, or NR-DC.

12. 2. The UE of claim 1, wherein to perform the handover procedure, the processor is configured to perform one or more of the following operations: automatic gain control (AGC) setting for the second PCell; downlink cell synchronization for the second PCell; time / frequency (T / F) tracking for the second PCell; software processing or radio frequency (RF) warm-up; synchronization signal block (SSB) processing; or primary synchronization signal (PSS) / secondary synchronization signal (SSS) detection.

13. 2. The UE of claim 1, wherein to perform the additional procedures, the processor is configured to perform one or more of the following operations: automatic gain control (AGC) setting for the PSCell; downlink cell synchronization for the PSCell; time / frequency (T / F) tracking for the PSCell; software processing or radio frequency (RF) warm-up; synchronization signal block (SSB) processing; or primary synchronization signal (PSS) / secondary synchronization signal (SSS) detection.

14. A method for a user equipment (UE), comprising: receiving a message from a first primary base station to perform a handover procedure to hand over the UE from a first primary base station to a second primary base station, where the UE communicates with the first primary base station in a first primary cell (PCell) and the second primary base station in a second PCell and has dual connectivity in the second PCell using a first wireless carrier to communicate with the second primary base station and using a second wireless carrier to communicate with a secondary base station in a primary secondary cell (PSCell); performing the handover procedure to handover the UE from the first primary base station to the second primary base station; performing an add procedure for the secondary base station in parallel with the handover procedure, where a start time of the add procedure is before an end time of the handover procedure; transmitting a first Random Access Channel (RACH) preamble to the second primary base station at a first time instance after the end time of the handover procedure; transmitting a second RACH preamble to the secondary base station at a second time instance after an end time of the addition procedure; A method comprising:

15. obtaining a RACH occasion for transmitting the second RACH preamble to the secondary base station before transmitting the second RACH preamble to the secondary base station; The method of claim 14 further comprising:

16. receiving a random access response (RAR) message from the second primary base station at a third time instance in response to the first RACH preamble transmitted to the second primary base station at the first time instance; The method of claim 14 further comprising:

17. The method of claim 16 , wherein the second time instance is after the third time instance, which is after the first time instance.

18. scheduling an uplink transmission to the second primary base station for a contention-based RACH (CBRA) after the third time instance; receiving an acknowledgment from the second primary base station at a fourth time instance, the second time instance being after the fourth time instance. The method of claim 14.

19. A non-transitory computer-readable medium storing instructions that, when executed by a processor of a user equipment (UE), cause the UE to perform an operation, the operation comprising: receiving a message from a first primary base station to perform a handover procedure to hand over the UE from a first primary base station to a second primary base station, where the UE communicates with the first primary base station in a first primary cell (PCell) and the second primary base station in a second PCell and has dual connectivity in the second PCell using a first wireless carrier to communicate with the second primary base station and using a second wireless carrier to communicate with a secondary base station in a primary secondary cell (PSCell); performing the handover procedure to handover the UE from the first primary base station to the second primary base station; performing an addition procedure of the secondary base station in parallel with the handover procedure, the start time of the addition procedure being before the end time of the handover procedure; transmitting a first Random Access Channel (RACH) preamble to the second primary base station at a first time instance after the end time of the handover procedure; transmitting a second RACH preamble to the secondary base station at a second time instance after an end time of the addition procedure; A non-transitory computer readable medium comprising:

20. The operation, Before transmitting the second RACH preamble to the secondary base station, obtaining a RACH occasion for transmitting the second RACH preamble to the secondary base station; 20. The non-transitory computer-readable medium of claim 19, further comprising: receiving a Random Access Response (RAR) message from the second primary base station at a third time instance in response to the first RACH preamble transmitted to the second primary base station at the first time instance.

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