Handover to primary and secondary base stations in dual connectivity

Abstract

Some aspects of the present disclosure relate to an apparatus and method for implementing techniques for a user equipment (UE) with dual connectivity. The UE can communicate 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 a second PCell, using a first radio carrier to communicate with the second primary base station and using a second radio 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. The UE performs the handover procedure according to the received message, and further performs an add procedure for the secondary base station in parallel with the handover procedure. The start time of the add procedure may be before the end time of the handover procedure.

Description

[Technical field]

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

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

[0003] Certain aspects of the present disclosure relate to apparatus and methods for implementing techniques for providing a solution for handover of a user equipment (UE) having dual connectivity to a primary base station and a secondary base station. The implemented techniques 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 UE. The UE may include a transceiver and a processor communicatively coupled to the transceiver. The transceiver may 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 may have dual connectivity in a 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). The processor of the UE is configured to receive a message from the first primary base station to perform a handover procedure for handing over the UE from the first primary base station to the second primary base station, and further perform the handover procedure according to the received message. Furthermore, the processor is configured to perform an additional procedure for the secondary base station in parallel with the handover procedure. A start time of the additional procedure may be before an end time of the handover procedure. Further, the processor is configured to send, using the transceiver, a first random access channel (RACH) preamble to the second primary base station at the first time instance and a second RACH preamble to the secondary base station at the second time instance.

[0005] In some examples, the first time instance is after an end time of the handover procedure and the second time instance is after an end time of the add procedure. In some examples, the start time of the add procedure 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 capability to support the handover procedure and the addition procedure in parallel. The processor may be configured to perform other operations, for example, a change procedure for the UE to change the secondary base station. In addition, the processor may be configured to obtain 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. Furthermore, 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 the first time instance. The second time instance may be after a third time instance that is after the first time instance. Furthermore, the processor may be configured to schedule an uplink transmission to the second primary base station for a 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 may 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 in a first PCell and communicates with a second primary base station in a second PCell. In addition, the UE has dual connectivity in a second PCell, using a first radio carrier to communicate with the second primary base station and using a second radio carrier to communicate with a secondary base station in a primary secondary cell (PSCell). The method includes receiving a message from the first primary base station to perform a handover procedure for handing 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. Furthermore, the method includes performing an addition procedure of the secondary base station in parallel with the handover procedure, where a start time of the addition procedure is before an end time of the handover procedure. Furthermore, 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 an end time of the handover procedure, and the second time instance is after an end time of the addition procedure.

[0008] Some aspects of the disclosure relate to a non-transitory computer-readable medium storing instructions. The instructions stored on the non-transitory computer-readable medium, when executed by a processor of the UE, cause the UE to perform various operations. The UE communicates with a first primary base station in a first PCell and communicates with a second primary base station in a second PCell. In addition, the UE has dual connectivity in a 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). The operations include receiving a message from the first primary base station to perform a handover procedure to handover the UE from the first primary base station to the second primary base station, and performing the handover procedure according to the received message. Furthermore, the operations include performing an addition procedure of a secondary base station in parallel with the handover procedure, where a start time of the addition procedure is before an end time of the handover procedure. Additionally, the operations include sending the first RACH preamble to the second primary base station at a first time instance and sending the second RACH preamble to the secondary base station at a second time instance, where the first time instance is after a termination time of the handover procedure and the second time instance is after a termination time of the addition procedure.

[0009] This summary of the invention is provided merely for the purpose of illustrating some aspects to provide an understanding of the subject matter described herein. Thus, 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, figures, and claims. [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, further serve to explain the principles of the present disclosure and to enable one skilled in the art(s) to make and use the present disclosure.

[0011] [Figure 1] FIG. 1 illustrates a wireless communication system including a user equipment (UE) having dual connectivity for performing handover of the UE to a primary base station and a secondary base station in accordance with certain aspects of the present disclosure.

[0012] [Diagram 2] FIG. 1 is a block diagram of a UE that performs functions described herein in accordance with certain aspects of the present disclosure.

[0013] [Diagram 3] 1 illustrates an example method performed by a UE having dual connectivity to perform a handover of the UE to a primary base station and a secondary base station in accordance with certain aspects of the present disclosure.

[0014] [Figure 4A] 1 illustrates an example method performed by a UE having dual connectivity to perform a handover of the UE to a primary base station and a secondary base station in accordance with certain aspects of the present disclosure. [Figure 4B] 1 illustrates an example method performed by a UE having dual connectivity to perform a handover of the UE to a primary base station and a secondary base station in accordance with certain aspects of the present disclosure. [Figure 4C] 1 illustrates an example method performed by a UE having dual connectivity to perform a handover of the UE to a primary base station and a secondary base station in accordance with certain aspects of the present disclosure. [Figure 4D]1 illustrates an example method performed by a UE having dual connectivity to perform a handover of the UE to a primary base station and a secondary base station in accordance with certain aspects of the present disclosure.

[0015] [Diagram 5] FIG. 1 illustrates an example computer system for implementing some aspects or portion(s) of the disclosure provided herein.

[0016] The present disclosure is described with reference to the accompanying drawings, in which like reference numbers generally indicate identical or functionally similar elements, and in which the left-most digit(s) of a reference number generally identifies the drawing in which the reference number first appears. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The embodiments herein present an exemplary solution for performing handover of a user equipment (UE) to a primary base station and a secondary base station by a dual connectivity (DC)-equipped UE. When a UE of a wireless communication system moves from one location to another, the UE may be served by different base stations, for example, a first base station, a second base station, a primary base station, a secondary base station, or a combination thereof. When the UE leaves a cell managed by a first base station and enters a cell managed by a second base station, the procedure may be referred to as a handover procedure for handing over the UE from the first base station to the second base station.

[0018] The embodiments herein present an exemplary handover procedure for a UE with DC. There may be various DCs. For example, there may 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. The embodiments herein are applicable to any dual connectivity known to those skilled in the art.

[0019] Initially, the UE may 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 may move out of the first PCell and into a second PCell, and the UE may have 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 the secondary base station. The secondary base station may be in a primary secondary cell (PSCell). In some embodiments, the PCell may refer to a primary base station in the PCell and the PSCell may refer to a secondary base station in the PSCell.

[0020] According to some aspects, the UE may receive an instruction to perform a handover procedure from a first primary base station at a first PCell. The instruction may be carried by a radio resource control (RRC) message. Based on the received instruction, the UE may perform a handover procedure to handover the UE from the first primary base station to the second primary base station. In addition, even if the instruction may only include an instruction to perform a handover procedure, the UE may perform an add procedure for the 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 add procedure are described below. The start time of the add procedure is before the end time of the handover procedure. This allows the terminal to perform operations for two procedures, e.g., the handover procedure and the add procedure, with one handover instruction. Furthermore, the handover procedure and the add procedure can be performed in parallel. Thus, the efficiency of handover of the UE from the first PCell to the second PCell having dual connectivity can be improved. This add procedure is only an example. The UE may perform other procedures, eg, modification procedures, in parallel with the handover procedure.

[0021] 1 illustrates a wireless communication system 100 including a user equipment (UE), e.g., UE 101, having dual connectivity for performing handover of the UE to a primary base station and a secondary base station in accordance with certain aspects of the present disclosure. The wireless communication system 100 is provided for illustrative purposes only and is not intended to limit aspects of the disclosure.

[0022] According to some aspects, the wireless communication system 100 may include, without limitation, 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 the cell 102, the base station 105 manages the cell 104, and the base station 107 manages the 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 stations may be referred to by other names known to those skilled in the art.

[0023] Initially, the UE 101 may communicate with the base station 103, which may be a first primary base station in the cell 102. When the UE 101 moves along the direction X, the UE 101 may establish dual connectivity in the cell 104 using the first wireless carrier 108 to communicate with the base station 105, which may be a second primary base station, and the second wireless carrier 109 to communicate with the base station 107, which may be a secondary base station. To establish dual connectivity in the cell 104 for the UE 101, the UE 101 may perform a handover procedure to communicate with the base station 105 to replace the base station 103. In addition, additional procedures may be performed so that the UE 101 may communicate with the base station 107. When the UE 101 continues to move along the X direction and moves out of the cell 106 covered by the base station 107 and into the coverage area of ​​another secondary base station, a change procedure may be performed so that the UE 101 may stop communicating with the base station 107 and start communicating with another secondary base station.

[0024] In some examples, the wireless communication system 100 may be a wireless system including dual connectivity having two different wireless technologies, e.g., NR, LTE, 5G, some other wireless technology, or a combination thereof. Although many examples are described herein in the context of NR or LTE technology, the wireless communication system 100 is not limited to such technologies. Instead, the wireless communication system 100 may be any communication system capable of performing UE handover to a primary base station and a secondary base station for a UE having dual connectivity. There may be other network entities in the wireless communication system 100, e.g., a network controller, a relay station, not shown but understood by those skilled in the art. The wireless communication system 100 may 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, the base station 103, the base station 105, and the base station 107 may be fixed stations or mobile stations. The base station 103, the base station 105, and the base station 107 may be referred to by other names such as base transceiver system (BTS), access point (AP), transmit / receive point (TRP), evolved Node B (eNB), next generation Node B or new radio Node B (gNB), next generation evolved Node B (ng-eNB), 5G Node B (NB), or other equivalent terms understood by those skilled in the art. In some examples, the base station 103, the base station 105, and the base station 107 may be interconnected to each other and / or to 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, the UE 101 may be fixed or mobile. The UE 101 may 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 equipment, a biosensor or device, a wearable device (smart watch, smart clothing, smart glasses, smart jewelry such as a smart wristband, a smart ring, or a smart bracelet), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicle component, a smart meter, an 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 over a wireless medium. For example, MTC and eMTC devices may include robots, drones, location tags, etc.

[0027] According to some aspects, within the cell 102, the UE 101 may 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, the UE 101 may establish dual connectivity in the cell 104 using a first wireless carrier 108 to communicate with the base station 105 and a second wireless carrier 109 to communicate with the base station 107. The dual connectivity for the UE 101 in the cell 104 may be EN-DC, NE-DC, NR-DC, or any other DC known to those skilled in the art. Thus, the first wireless carrier 108 may operate using LTE, NR, E-UTRA, or any other wireless technology, and the second wireless carrier 109 may operate using LTE, NR, E-UTRA, or any other wireless technology. A handover from the base station 103 in the cell 102 to a DC in the cell 104 may be an NR SA to EN-DC handover, an EN-DC to EN-DC handover, an NE-DC to NE-DC handover, an NR-DC to NR-DC handover, or some other DC handover.

[0029] According to some aspects, the UE 101 can receive a message 113 from the base station 105 to perform a handover procedure for handing over the UE 101 from the base station 103 to the base station 105. In some examples, the instruction can be carried by an RRC message. According to the message 113, the UE 101 can perform a handover procedure for handing over the UE 101 from the base station 103 to the base station 105 and perform an add procedure for the base station 107 in parallel with the handover procedure. The start time of the add procedure can be before the end time of the handover procedure. For example, the start time of the add procedure can be the same time instance as the start time of the handover procedure. Furthermore, the UE 101 can send an indication to the base station 103 to indicate that the UE 101 has the capability to support the handover procedure and the add procedure in parallel. In some examples, the indication is further configured as a per-UE indication, a per-band combined (BC) indication, or a per-band BC indication. Details of the handover procedure and the add procedure are described below. Once the handover is completed, the UE 101 may further perform a change procedure for the UE 101 to change the base station 107 to another base station while maintaining the DC with the base station 105.

[0030] In some examples, the handover procedure performed by the UE 101 may include one or more of automatic gain control (AGC) settling 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 may 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 in which the UE 101 wishes to create an initial connection with a 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 an end time of a handover procedure and the second time instance is after an end time of an addition 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 a 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 a contention-based RACH (CBRA) after the third time instance and receive an acknowledgment 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, the UE 101 may be implemented according to a block diagram as shown in FIG. 2. The UE 101 may have an antenna panel 217 including one or more antenna elements for forming various antenna beams, e.g., beam 219, coupled to the transceiver 203 and controlled by the processor 209. In particular, the transceiver 203 may include a radio frequency (RF) circuit 216, a transmit circuit 212, and a receive circuit 214. The RF circuit 216 may include multiple parallel RF chains for one or more of the transmit or receive functions, each of which is connected to one or more antenna elements of the antenna panel. In addition, the processor 209 may be communicatively coupled to a memory device 201, which is further coupled to the transceiver 203. Various data may be stored in the memory device 201. In some examples, the memory device 201 may store the message 113, the first RACH preamble 115, and the second RACH preamble 117, described above. The memory device 201 may include instructions that, when executed by the processor 209, perform the handover procedure and additional procedure related functions described herein. Alternatively, the processor 209 may be "hard-coded" to perform the location related functions described herein.

[0036] 3 illustrates an example method 300 performed by a UE having dual connectivity to perform a handover of the UE to a primary base station and a secondary base station in accordance with certain aspects of the disclosure. The method 300 may be performed (or controlled) by a processor 209 in coordination with other components of the UE 101. More specifically, the processor 209 may execute instructions stored in the memory 201 to perform the operations described below for the UE 101, or the processor 209 may be "hard-coded" to perform the operations described below for the UE 101.

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

[0038] At 303, the UE 101 may perform 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 may perform a handover procedure to hand over the UE 101 from the base station 103 to the base station 105.

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

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

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

[0042] 4A-4D illustrate example 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 in accordance with certain aspects of the disclosure. Method 410, method 420, method 430, and method 440 may be performed by a processor 209 of the 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] The method 410 is illustrated in Figure 4A, which 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 the UE 101 from a first primary base station to a second primary base station. The operations are marked as being performed at various time instances.

[0044] At time instance T411, UE 101 may perform operations to receive an RRC message including a command to perform a handover procedure at 411. The operations performed at 411 may be similar to the operations performed at 301 of the method 300 shown in FIG.

[0045] At time instance T412, UE 101 finishes processing the RRC message. The time delay between time instances T411 and T412 is T RRC-手順-遅延 , which is long enough for the UE 101 to finish processing the RRC messages and identify the commands or instructions to perform the handover procedure. RRC-手順-遅延 may also include a period to wait for the RACH occasion.

[0046] At time instance T412, at 413, the UE 101 may initiate a handover procedure to hand over the UE 101 to a target PCell, e.g., to hand over the UE 101 from the base station 103 to the base station 105. The operations performed at 413 may be similar to the operations performed at 303 shown in FIG.

[0047] At time instance T412, target PSCell addition starts at 415. For example, operations for an addition procedure for base station 107 may be performed so that base station 107 can serve UE 101. The operations performed at 415 may 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 may have different start times. For example, the operations at 415 for the addition procedure may 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 3. At the same time, in 419, the UE 101 may send a RACH preamble to the target PSCell. For example, the UE 101 may send a second RACH preamble 117 to the base station 107. The operations performed in 419 may be similar to the operations performed in 309 shown in FIG.

[0049] At time instance T414, the operations for the handover procedure to handover the UE 101 to the target PCell are completed. The time gap between time instance T412 and time instance T414 is T 割込み At the same time, at 417, the UE 101 may send a RACH preamble to the target PCell. For example, the UE 101 may send the first RACH preamble 115 to the base station 105. The operations performed at 417 may be similar to the operations performed at 307 shown in FIG.

[0050] As shown in Figure 4A, the operation at 419 for transmitting a RACH preamble to the target PSCell and the operation at 417 for transmitting a RACH preamble to the target PCell are performed independently, without any restriction on the time order between the two events. As shown in Figure 4A, the operation at 419 is performed at a time instance T413 that is earlier than the time instance T414. In some other embodiments, the operation at 419 may be performed after the time instance T414 at which the operation at 417 is performed.

[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}. T RRC-手順-遅延 is the RRC message processing time for handover between primary base stations, which is similar to the traditional handover time without dual connectivity. 割込み is the time to complete the handover procedure for handing over the UE 101 to a target PCell, e.g., base station 105. add-PSCell is the time to complete the target PSCell addition procedure, e.g., to perform the addition procedure for the base station 107. T add-PSCell and T 割込み Both T may include the time to wait for the RACH occasion. add-PSCell can include time to perform operations such as automatic gain control (AGC) settling 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. Interrupt may include time to perform operations such as AGC settling for the second PCell, downlink cell synchronization for 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 illustrates operations performed along two parallel timelines: a PSCell addition timeline illustrating operations performed for a secondary base station, and a PCell handover timeline illustrating operations performed for handover of UE 101 from a first primary base station to a second primary base station.

[0053] At time instance T421, UE 101 may perform an operation to receive an RRC message including a command to perform a handover procedure at 421. The operation performed at 421 may be similar to the operation performed at 301 of the method 300 shown in FIG. 3. At time instance T422, UE 101 may perform an operation to receive an RRC message including a command to perform a handover procedure at 301. RRC-手順-遅延 After that, the RRC message processing is completed.

[0054] At time instance T422, at 423, the UE 101 may initiate a handover procedure to hand over the UE 101 to a target PCell, e.g., to hand over the UE 101 from the base station 103 to the base station 105. The operations performed at 423 may be similar to the operations performed at 303 shown in FIG.

[0055] At time instance T422, target PSCell addition starts at 425. For example, operations for an addition procedure for the base station 107 may be performed so that the base station 107 can serve the UE 101. The operations performed at 425 may be similar to the operations performed at 305 shown in FIG. 3. FIG. 4B shows that the operations at 423 and 425 are performed simultaneously. In some other examples, they may have different start times. At time instance T423, the operations for target PSCell addition are completed. The time gap between time instance T422 and time instance T423 is T add-PSCell At time instance T424, the operations for the handover procedure to handover the UE 101 to the target PCell are shown as T Interrupt has been completed after a time gap of

[0056] At time instance T424, the UE 101 may transmit a RACH preamble to the target PCell at 427. For example, the UE 101 may send the first RACH preamble 115 to the base station 105. The operations performed at 427 may be similar to the operations performed at 307 shown in FIG. 3. The UE 101 further determines a time period T425 for the next available RACH to the PSCell, which is available at time instance T425. RO Wait for a period of time.

[0057] At time instance T425, the UE 101 may transmit a RACH preamble to the target PSCell at 429. For example, the UE 101 may send a second RACH preamble 117 to the base station 107. The operations performed at 429 may be similar to the operations performed at 309 shown in FIG.

[0058] Further, at time instance T426, the UE 101 may receive 428 a random access response (RAR) message from the target PCell in response to the RACH preamble transmitted to the PCell. For example, the UE 101 may receive a RAR message from the base station 105 in response to the first RACH preamble 115 transmitted to the base station 105. The time gap between T424 and T426 is T msg2 It can be expressed as:

[0059] As shown in FIG. 4B, 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}+T RO It can be shown as:

[0060] Similar to method 410, method 430 in FIG. 4C illustrates operations performed along two parallel timelines: a PSCell addition timeline illustrating operations performed for a secondary base station, and a PCell handover timeline illustrating operations performed for handover of UE 101 from a first primary base station to a second primary base station.

[0061] At time instance T431, UE 101 may perform operations to receive an RRC message including a command to perform a handover procedure at 431. The operations performed at 431 may be similar to the operations performed at 301 of the method 300 shown in FIG. 3. At time instance T432, UE 101 may receive an RRC message including a command to perform a handover procedure at a time delay T RRC-手順-遅延 After that, the RRC message processing is completed.

[0062] At time instance T432, at 433, the UE 101 may initiate a handover procedure to hand over the UE 101 to a target PCell, e.g., to hand over the UE 101 from the base station 103 to the base station 105. The operations performed at 433 may be similar to the operations performed at 303 shown in FIG.

[0063] At time instance T432, target PSCell addition starts at 435. For example, operations for an addition procedure for the base station 107 may be performed so that the base station 107 can serve the UE 101. The operations performed at 435 may be similar to the operations performed at 305 shown in FIG. 3. FIG. 4C shows that the operations at 433 and 435 are performed simultaneously. In some other examples, they may have different start times. At time instance T433, the operations for target PSCell addition are completed. The time gap between time instance T432 and time instance T433 is T add-PSCellAt time instance T434, the operations for the handover procedure to handover the UE 101 to the target PCell are shown as T Interrupt has been completed after a time gap of

[0064] At time instance T434, the UE 101 may transmit a RACH preamble to the target PCell at 437. For example, the UE 101 may send the first RACH preamble 115 to the base station 105. The operations performed at 437 may be similar to the operations performed at 307 shown in FIG. 3. Furthermore, at time instance T435, the UE 101 may receive a RAR message from the target PCell at 438 in response to the RACH preamble sent to the PCell. For example, the UE 101 may receive a RAR message from the base station 105 in response to the first RACH preamble 115 sent to the base station 105. The time gap between time instance T434 and time instance T435 may be T msg2 UE 101 may further select the time period T for the next available RACH to the PSCell, which is available in T436. RO Wait for a period of time.

[0065] At time instance T436, the UE 101 may transmit a RACH preamble to the target PSCell at 439. For example, the UE 101 may send a second RACH preamble 117 to the base station 107. The operations performed at 439 may be similar to the operations performed at 309 shown in FIG.

[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 It can be shown as:

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

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

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

[0070] At time instance T442, target PSCell addition starts at 445. For example, operations for an addition procedure for the base station 107 may be performed so that the base station 107 can serve the UE 101. The operations performed at 445 may be similar to the operations performed at 305 shown in FIG. 3. FIG. 4D shows that the operations at 443 and 445 are performed simultaneously. In some other examples, they may 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-PSCellAt time instance T444, the operation of the handover procedure for handing over the UE 101 to the target PCell is shown as T Interrupt has been completed after a time gap of

[0071] At time instance T444, the UE 101 may transmit a RACH preamble to the target PCell at 447. For example, the UE 101 may send the first RACH preamble 115 to the base station 105. The operations performed at 447 may be similar to the operations performed at 307 shown in FIG. 3. Furthermore, at time instance T445, the UE 101 may receive a RAR message from the target PCell at 448 in response to the RACH preamble sent to the PCell. For example, the UE 101 may receive a RAR message from the base station 105 in response to the first RACH preamble 115 sent to the base station 105. The time gap between time instance T444 and time instance T445 may be T msg2 It could be.

[0072] At time instance T446, UE 101 may schedule 451 an uplink transmission to the second primary base station for a contention-based RACH (CBRA). At time instance T447, UE 101 may receive 453 an acknowledgment from the second primary base station at a fourth time instance. The time gap between time instance T445 and time instance T447 is T msg4 After the time instance T447, the UE 101 may further select a period T for the next available RACH to the PSCell, which is available at T448. RO Wait for a period of time.

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

[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 It can be shown as:

[0075] Various aspects may be implemented using one or more computer systems, such as computer system 500 shown in FIG. 5. Computer system 500 may be any computer capable of performing operations described herein, such as UE 101, base station 103, base station 105, base station 107 as shown in FIGS. 1-2, and operations described in FIGS. 3 and 4A-4D. Computer system 500 includes one or more processors (also referred to as central processing units, or CPUs), such as processor 504. Processor 504 is connected (e.g., by a bus) to a communication infrastructure 506. Computer system 500 also includes user input / output device(s) 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 a main or primary memory 508, such as a 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 memories 510. The secondary memory 510 may include, for example, a hard disk drive 512 and / or a removable storage device or drive 514. The removable storage drive 514 may be a floppy disk drive, a magnetic tape drive, a compact disk drive, an optical storage device, a tape backup device, and / or any other storage device / drive.

[0077] The removable storage drive 514 may interface with a removable storage unit 518. The removable storage unit 518 includes a computer usable or computer readable storage device on which computer software (control logic) and / or data is stored. The 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. The removable storage drive 514 reads from and / or writes to the removable storage unit 518 in a well-known manner.

[0078] According to some aspects, secondary memory 510 may include other means, instrumentalities, and other techniques for making computer programs and / or other instructions and / or data accessible by computer system 500. Examples of such means, instrumentalities, and other techniques may include, for example, removable storage unit 522 and interface 520. Examples of removable storage unit 522 and interface 520 may include program cartridges and cartridge interfaces (such as those found in video game devices), removable memory chips (such as EPROMs or PROMs) and associated sockets, memory sticks and USB ports, memory cards and associated memory card slots, and / or any other removable storage units and associated interfaces.

[0079] In some examples, the main memory 508, the removable storage unit 518, 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 base station, such as UE 101, base station 103, base station 105, base station 107, for example, as shown in Figures 1-2 and described in Figures 3 and 4A-4D.

[0080] The computer system 500 may further include a communication or network interface 524. The communication interface 524 enables the computer system 500 to communicate and interact with any combination of remote devices, remote networks, remote entities, etc. (individually and collectively referred to by reference number 528). For example, the communication interface 524 may enable the computer system 500 to communicate with the remote devices 528 over a communication path 526, which may be wired and / or wireless and may include any combination of a LAN, a WAN, the Internet, etc. Control logic and / or data may be transmitted to and from the computer system 500 via the communication path 526. The operations 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 communications according to different wireless communication technologies. The operations in the aforementioned aspects may be implemented in a wide variety of configurations and architectures. Thus, some or all of the operations in the aforementioned aspects may be performed in hardware, software, or both. In some aspects, a tangible non-transitory apparatus or article of manufacture is also referred to herein 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, computer system 500, main memory 508, secondary memory 510, removable storage units 518 and 522, and tangible articles of manufacture embodying any combination of the foregoing. Such control logic, when executed by one or more data processing devices (such as 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 one of ordinary skill in the relevant art(s) how to make and use aspects of the present disclosure using data processing devices, computer systems and / or computer architectures other than those shown in Figure 5. In particular, aspects may operate with software, hardware, and / or operating system implementations other than those described herein.

[0082] It is understood that it is the "Description of Embodiments" section, and not the "Summary" and "Abstract" sections, that are intended to be used to interpret the claims. The Summary and Abstract sections may describe one or more exemplary aspects of the disclosure, but not all of the exemplary aspects of the disclosure, as contemplated by the inventor(s), and thus are not intended to limit the scope of the disclosure or the appended claims in any way.

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

[0084] Aspects have been described herein with the aid of functional building blocks illustrating implementations of certain functions and relationships thereof. Boundaries of these functional building blocks have been arbitrarily defined herein for convenience of description. Alternative boundaries may be defined so long as the specified functions and relationships (or their equivalents) are appropriately performed. In addition, alternative aspects may perform functional blocks, steps, operations, methods, etc. using an order different from that described herein.

[0085] Reference herein to "one embodiment," "one embodiment," "exemplary embodiment," or similar phrases indicates that the described embodiment may include a particular feature, structure, or characteristic, but not all embodiments may necessarily include the particular feature, structure, or characteristic. Also, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with one embodiment, it is within the knowledge of one of ordinary skill in the relevant art(s) to incorporate such particular feature, structure, or characteristic in other aspects, whether or not expressly mentioned or described herein.

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

[0087] In one or more embodiments, for example, at least one of the components depicted in one or more of the preceding figures may be configured to perform one or more of the operations, techniques, processes, and / or methods as described in the Examples section below. For example, circuitry associated with a sled device, router, network element, etc. described above in connection with one or more of the preceding figures may be configured to operate according to one or more of the examples described in the Examples section below.

[0088] This disclosure contemplates that entities involved in the collection, analysis, disclosure, transmission, storage, or other use of such personal information data will adhere to robust 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 maintaining personal information data as strictly confidential. Such policies should be easily accessible by users and should be updated as data collection and / or use changes. Personal information from users should be collected for the entity's lawful and legitimate use and should not be shared or sold except for those lawful uses. Moreover, such collection / sharing should only be carried out after the user is informed and consented to. Moreover, such entities should consider taking all necessary measures to protect and secure access to such personal information data and ensure that others with access to the personal information data adhere to their privacy policies and procedures. Furthermore, such entities may subject themselves to third-party assessments to attest to their adherence to widely accepted privacy policies and practices. Moreover, policies and practices should be adapted to the specific types of personal information data collected and / or accessed, and should be adapted to applicable laws and standards, including jurisdiction-specific considerations. For example, in the United States, collection or access of certain health data may be governed 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 other regulations and policies and should be addressed accordingly. Therefore, different privacy practices should be maintained with respect to 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 an end 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 the 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 a 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 an end 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 the 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.

17. The method of claim 16.

19. A computer program having instructions which, 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 end 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 the end time of the addition procedure; A computer program 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 computer program product 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 sent to the second primary base station at the first time instance.

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