Delivery of accurate reference timing during switching

Abstract

The present application provides some methods for user equipment (UE) to obtain accurate reference timing of the target cell during the handover process. This solution ensures that the UE meets the synchronization accuracy requirements during the handover process and guarantees the continuity of time-sensitive services.

Description

Technical Field

[0001] The present application relates to the field of communication systems, and more particularly, to the delivery of accurate reference timing during a handover process. Background Art

[0002] Wireless communication systems such as third-generation (3G) mobile phone standards and technologies are well known. The Third Generation Partnership Project (3GPP) has developed such 3G standards and technologies. Generally speaking, third-generation wireless communications have been developed to support macro-cell mobile phone communications, and communication systems and networks have developed towards broadband and mobile systems. In a cellular wireless communication system, user equipment (UE) is connected to a radio access network (RAN) via a wireless link. The RAN includes a group of base stations that provide wireless links to UEs located in the cells covered by the base stations and include an interface to the core network (CN), which has the function of controlling the entire network. It can be understood that the RAN and CN each perform corresponding functions related to the entire network. The 3rd Generation Partnership Project has developed the so-called Long Term Evolution (LTE) system, the Evolved Universal Mobile Telecommunication System Territorial Radio Access Network (E-UTRAN), for a mobile access network of one or more macro cells supported by base stations called eNodeB or eNB (evolved NodeB). More recently, LTE has further evolved into the so-called 5G or New Radio (NR) system, in which one or more cells are supported by base stations called gNBs.

[0003] Time Sensitive Network (TSN) is a set of standards developed by IEEE (IEEE802.1Q TSN standard) to define the mechanism of time-sensitive data transmission and accurate timing reference on wired Ethernet network (IEEE 802.3 Ethernet standard). This accurate reference timing comes from a central clock source, called Grand Master, which is distributed through a series of hops between nodes based on Precision Time Protocol (PTP), namely IEEE 1588 Precision Time Protocol.

[0004] As stated in SA1 TR 22.804 and TR 22.821 and documented as a key topic in TR 23.734 (Key Topic #3), one of the key requirements for NR systems is to support some form of interworking with Time Sensitive Networking (TSN).

[0005] RAN2#103bis stipulates that the NR system acts as a "black box" in the TSN network. Figure 2 In this way, TSN provides accurate reference timing to the NR system, such as Figure 1 As shown in Figure 1. The NR system is essentially what the IEEE calls a "Boundary Clock (BC)". As a master clock for all connected nodes (represented by the dashed box), the NR system is able to distribute TSN-derived accurate timing to all UEs in the system. In addition, the NR system is able to compensate for time drift caused by delays in the air interface, which is a topic discussed in NR Industrial Internet of Things (IIoT) related research. The NR system timing maintained by the UE is distributed as PTP packets to all devices connected to its Ethernet port.

[0006] For latency-sensitive services (e.g., NR IIoT services, XR), if the system lacks an accurate reference timing delivery mechanism, it will be difficult to meet the synchronization accuracy requirements of latency-sensitive services. In particular, for mobile UEs, time synchronization accuracy will be a key issue affecting UEs’ execution of time-sensitive services. Therefore, the delivery of accurate reference timing during the handover process will be an issue to be solved. Summary of the invention

[0007] The first aspect of the present application provides a time synchronization method performed during the switching process of a user equipment (UE) between a source base station and a target base station in a cellular wireless communication system. The method is performed by the target base station and includes: receiving or obtaining information related to time-sensitive communication (TSC) including an accurate reference timing request during the switching process; and delivering accurate reference timing to the UE during the switching process in response to the accurate reference timing request.

[0008] A second aspect of the present application provides a time synchronization method performed during a switching process of a user equipment (UE) between a source base station and a target base station in a cellular wireless communication system. The method is performed by the source base station and includes: receiving or acquiring information related to accurate reference timing; sending the information related to accurate reference timing to the target base station during the switching process; receiving the information related to accurate reference timing from the target base station; and forwarding the received information related to accurate reference timing to the UE during the switching process.

[0009] A third aspect of the present application provides a time synchronization method performed during the switching process of a user equipment (UE) between a source base station and a target base station in a cellular wireless communication system. The method is performed by the UE and includes: receiving an accurate reference timing sent by the target base station during the switching process; and synchronizing with the target base station using the accurate reference timing.

[0010] A fourth aspect of the present application provides a switching decision method, which is executed by a serving cell of a serving user equipment (UE), and the method includes: obtaining neighboring cell information about whether the neighboring cell meets the accurate reference timing requirements; sending a measurement configuration related to time-sensitive services including neighboring cells that meet the accurate reference timing requirements; receiving a measurement report related to time-sensitive services reported based on the measurement configuration related to the time-sensitive services; and selecting a candidate cell for switching based on the measurement report related to the time-sensitive services.

[0011] The fifth aspect of the present application provides a measurement and reporting method, which is performed by a user equipment (UE) and includes: receiving or obtaining a measurement configuration related to time-sensitive services including a neighboring cell that meets the accurate reference timing requirements; performing measurements related to time-sensitive services on the neighboring cell that meets the accurate reference timing requirements to generate a measurement report related to the time-sensitive services; and sending the measurement report related to the time-sensitive services.

[0012] The disclosed method may be implemented in a user equipment, a source base station or a target base station.

[0013] The disclosed methods may be programmed as computer-executable instructions stored in a non-transitory computer-readable medium, which, when loaded into a computer, instructs a processor of the computer to perform the disclosed methods.

[0014] The non-transitory computer readable medium may include at least one of the group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a read-only memory, a programmable read-only memory, an erasable programmable read-only memory, an electrically erasable programmable read-only memory, and a flash memory.

[0015] The disclosed method can be programmed as a computer program product, which causes a computer to perform the disclosed method.

[0016] The disclosed method can be programmed as a computer program, which causes a computer to perform the disclosed method.

[0017] The disclosed solution ensures that a moving UE supporting a time-sensitive service meets the synchronization accuracy requirement during a handover process, thereby guaranteeing the continuity of the time-sensitive service. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or related technologies, the following drawings will be described in the embodiments and briefly introduced as follows. It is obvious that these drawings only present some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without making any assumptions.

[0019] Figure 1 Schematic diagram showing the high-level architecture of TSN with 5G.

[0020] Figure 2 Schematic diagram showing the NR system as a black box in a TSN network.

[0021] Figure 3 A flowchart of a time synchronization method during a switching process according to the first embodiment of the present application is shown.

[0022] Figure 4 A flowchart of a time synchronization method during a switching process according to a second embodiment of the present application is shown.

[0023] Figure 5 A flowchart of a time synchronization method during a switching process according to a third embodiment of the present application is shown.

[0024] Figure 6 A flow chart of a cell (re)selection method according to a fourth embodiment of the present application is shown.

[0025] Figure 7 A block diagram of a system for wireless communication according to an embodiment of the present application is shown.

[0026] Figure 8 Schematic diagram showing the switching process. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings of the present application to describe the embodiments of the present application in detail in terms of technical solutions, structural features, objectives and effects achieved. Specifically, the terms in the embodiments of the present application are only used to describe certain embodiments and are not used to limit the content of the present application.

[0028] Mobility is one of the important issues, so a mechanism is needed to ensure that the time synchronization accuracy meets the requirements during the handover process. In other words, the accurate reference timing of the target cell should be sent to the user equipment (UE) as soon as possible.

[0029] In this application, some methods are disclosed, which enable the UE to obtain the accurate reference timing of the target cell during the handover process. This solution ensures that the UE meets the synchronization accuracy requirements during the handover procedure and ensures the continuity of time-sensitive services (such as time-sensitive network (TSN) services).

[0030] During the switching process, the UE switching is performed between a source base station (e.g., a source gNB) and a target base station (e.g., a target gNB) in a cellular wireless communication system. The main inventive concept of the present application is that during the switching process, the target base station can obtain time-sensitive communication (TSC) related information from the source base station or from the core network (CN) or the network (NW) (e.g., 5G core network (5GC)), and then the target base station provides the UE with an accurate reference timing during the switching process. Therefore, the UE can synchronize with the target base station as quickly as possible, and its synchronization accuracy meets the requirements of time-sensitive services, and the time-sensitive services will not be interrupted due to synchronization failure or poor synchronization accuracy.

[0031] On the other hand, the serving cell (e.g., a serving gNB) serving the UE can obtain neighboring cell information to understand whether the neighboring cell supports time-sensitive services or meets the requirements of accurate reference timing, and configure the UE to measure the neighboring cell that supports time-sensitive services. The UE generates a measurement report and sends it to the serving cell. Then, the serving cell makes a switching decision based on the measurement report and / or the neighboring cell information, that is, the serving cell decides whether to switch the UE to the neighboring cell and / or which cell to switch to. In addition, the base station can broadcast system information (SI) related to accurate reference timing by broadcasting a system information block (e.g., SIB9). UEs in RRC_IDLE state and RRC_INACTIVE state receive SI during random access and perform cell (re)selection based on the acquired SI.

[0032] Example 1

[0033] This embodiment mainly focuses on providing TSC related information including an accurate reference timing request to the target base station during the handover preparation phase. If the target base station supports time-sensitive services (e.g., TSN related services) and its corresponding accurate reference timing meets the requirements, the target base station sends or transmits the accurate reference timing to the UE during the handover preparation phase.

[0034] The TSC-related information obtained by the target base station may include an accurate reference timing request message and may also include TSC Assistance Information (TSCAI). TSCAI itself describes the TSC traffic characteristics. For example, knowledge of TSN traffic patterns helps understand the periodicity and latency requirements so that the UE can determine the time synchronization accuracy and uncertainty of the reference timing.

[0035] TSCAI includes at least information related to the service type or information related to the reference timing. The information related to the service type can be in any form, for example, an indicator such as S-NSSAI. The information related to the reference timing is composed of at least one of the information elements (IE) contained in SIB9 and DLInformationTransfer, such as clock type, uncertainty, etc., or any other information, such as speed, periodicity. The content and form of the accurate reference timing request message are not limited or have not been standardized. TSCAI may contain any other information, such as UE location information, the distance between the UE and the base station, location information, etc.

[0036] The source base station may obtain information related to accurate reference timing from at least one of the UE and the core network (e.g., 5GC), or be pre-configured. In one embodiment, during the switching preparation phase, the source base station sends information related to accurate reference timing including an accurate reference timing request to the target base station, and then receives information related to accurate reference timing including an accurate reference timing response from the target base station through the Xn interface. The source base station then forwards the information related to accurate reference timing to the UE. The information related to accurate reference timing sent from the source base station to the target base station may also include TSCAI. In another embodiment, during the switching preparation phase, the source base station sends an accurate reference timing request to the target base station, and then the target base station obtains the relevant TSCAI from the core network. This TSCAI is required to determine whether the target base station meets the requirements of the accurate reference timing supported by the UE and whether or how and in what manner to deliver the accurate reference timing to the UE. The judgment of whether the target base station meets the requirements can be based on the accurate reference timing request message obtained from the source base station and all or part of the TSCAI; or, the judgment of whether the target base station meets the requirements can be based on the accurate reference timing request message obtained from the source base station and the TSCAI obtained from the core network.

[0037] After receiving the above-mentioned information related to the accurate reference timing, the target base station will deliver the accurate reference timing to the UE. The target base station can provide the UE with information related to the accurate reference timing in various ways and forms. For example, the target base station can send the information related to the accurate reference timing to the source base station through the Xn interface or through the core network (such as 5GC), and then the source base station can send or forward a message to the UE in the following ways: broadcast SIB, unicast signaling of Radio Resource Control (RRC), carried or carried in user data, MAC control element (MAC CE) or any other way. In another way, the target base station can periodically broadcast SI related to the accurate reference timing, and send or deliver messages or information related to the accurate reference timing through downlink transmission (e.g., random access response (RAR) message) during the switching process, or by forwarding the context to the UE during the context exchange phase during the switching process.

[0038] The UE receives a message or information related to the accurate reference timing from the target base station and performs handover.

[0039] Figure 3A flowchart of a time synchronization method during a handover according to the first embodiment of the present application is shown. UE handover is performed between a source base station (e.g., source gNB) and a target base station (e.g., target gNB). Assume that 1) both the UE and the source base station support TSN services; 2) the UE is connected to the source base station and is in RRC_CONNECTED state; 3) the UE is performing measurements and measurement reports; 4) the handover conditions are met.

[0040] refer to Figure 3 , the source base station obtains TSCAI related to time-sensitive services (e.g., TSN services) supported by the UE. There may be various ways for the source base station to obtain TSCAI from and how to obtain it. The specific composition of TSCAI may be currently standardized or comply with other standards. In one embodiment, the source base station receives TSCAI from the UE, as in step 0a. In another embodiment, the source base station obtains TSCAI from the core network (e.g., 5GC), as in step 0b. In yet another embodiment, TSCAI may be pre-configured or standardized. The source base station may obtain TSCAI through at least one of the above embodiments. TSCAI may be any information related to the delivery of accurate reference timing.

[0041] In step 1, a source base station sends an accurate reference timing (ART) request message to a selected target base station.

[0042] The accurate reference timing request message may include an accurate reference timing request and may also include a portion of the TSCAI. The specific content and form of the accurate reference timing request message are not specified or limited, and is used to let the target base station understand the requirements of the UE's time-sensitive services for accurate reference timing.

[0043] The accurate reference timing request message sent by the source base station to the target base station may be obtained from the UE or generated by the source base station. In one embodiment, the UE sends a measurement report to the source base station, and then the source base station generates an accurate reference timing request message and sends it to the target base station. In another embodiment, the UE sends an accurate reference timing request message to the source base station, and the source base station forwards the accurate reference timing request message to the target base station.

[0044] In one embodiment, the source base station may send an accurate reference timing request message carried by a handover command (e.g., a HANDOVER REQUEST message) or carried in a handover command. In another embodiment, a bit or a field having several bits in the handover command may be used to indicate that the target base station should support accurate reference timing or perform accurate reference timing transfer. Any combination of the embodiments described in the present application is permitted.

[0045] In step 2, the target base station receives an accurate reference timing request from the accurate reference timing request message of the source base station, performs admission control, and sends a response message to the source base station.

[0046] The target base station may need some information to determine whether it meets the requirements of accurate reference timing for time-sensitive services (e.g., TSN services) supported by the UE. In one embodiment, such information can be obtained from the core network (e.g., 5GC), as shown in step 2a. In another embodiment, such information can be extracted from the accurate reference timing request message sent by the source base station.

[0047] If the target base station does not meet the time-sensitive service requirements of the UE, the handover request is rejected, and as shown in step 2b, a handover rejection message such as HANDOVER REQUEST REJECT is sent from the target base station to the source base station.

[0048] In one embodiment, if the target base station accepts the handover request, as shown in step 2c, a handover request confirmation message such as a HANDOVER REQUEST ACKNOWLEDGE message is sent from the target base station to the source base station, and the accurate reference timing response message can be carried or carried in any form in the handover request confirmation message. In another embodiment, if the target base station accepts the handover request, a handover request confirmation message such as a HANDOVER REQUESTACKNOWLEDGE message is sent from the target base station to the source base station, and the target base station periodically broadcasts system information (SI) related to the accurate reference timing (e.g., SIB9), as shown in step 3b. The period and time can be inferred from at least one of the accurate reference timing request message and the TSCAI. The action of the target base station can be any combination of the above embodiments.

[0049] In step 3, the UE obtains accurate reference timing and performs handover.

[0050] In one embodiment, the UE obtains the accurate reference timing by receiving an accurate reference timing response message from the source base station. In another embodiment, the UE receives SI broadcast related to the accurate reference timing from the target base station.

[0051] Example 2

[0052] This embodiment discloses a method for requesting accurate reference timing in a random access procedure initiated during a handover process.

[0053] The UE uses a dedicated random access preamble or random access time-frequency resource to start the random access procedure initiated by the handover process, and can indicate the accurate reference timing request to the target base station through the dedicated random access preamble or random access time-frequency resource. Alternatively, the accurate reference timing request can be sent to the target base station and carried or carried by the random access preamble packet or message 3. The target base station can then use the message related to the accurate reference timing included in the RAR or message 4 to perform the delivery of the accurate reference timing. SIB broadcasting can be another way to send accurate reference timing.

[0054] Figure 4 A flowchart of a time synchronization method during a handover process according to a second embodiment of the present application is shown. UE handover is performed between a source base station (e.g., a source gNB) and a target base station (e.g., a target gNB). Assume that 1) both the UE and the source base station support time-sensitive services; 2) the UE is connected to the source base station and is in the RRC_CONNECTED state; 3) the UE is performing measurements and measurement reports; 4) the handover procedure is triggered; and 5) the random access initiated by the handover process can be a contention-free random access and a contention-based random access.

[0055] For the scenario of contention-free random access:

[0056] refer to Figure 4 In step 0, the source base station sends an RRCConnectionReconfiguration message to the UE, instructing the UE to perform contention-free random access. Dedicated time-frequency resources can be allocated to the UE to perform the random access procedure, and the available configurations or regulations can be contention-free random access, contention-based random access, or both. The above configurations can be RACH-ConfigIndex, prach Mask Index, ra-PreambleIndex in RACH-ConfigDedicated, Preamble Index in DCI format 1A, etc.

[0057] For contention-free random access, one or more preambles may be used to indicate to the target base station that the UE sends a dedicated random access preamble supporting time-sensitive services, and requires accurate reference timing delivery. The above rules may be standardized, configurable, or implementation-level, etc. The configuration of which time-frequency resources and / or preambles the UE uses for random access may be sent to the UE by being carried or included in the RRCConnectionReconfiguration message.

[0058] This application does not make any specific provisions or restrictions on the details of how the source base station instructs the UE and the content of the instruction, which can be any combination of the above method and other methods.

[0059] In step 1, the UE sends a random access preamble to the target base station using a dedicated preamble and / or time-frequency resources as configured / standardized. The preamble index and prach Mask Index indicate that this random access is initiated by a UE supporting time-sensitive services. The target base station recognizes that the random access preamble sent by the UE requires a delivery service with accurate reference timing, and then the target base station decides whether to accept this access and how to respond.

[0060] In step 2, the target base station receives the random access preamble, then performs the transfer of accurate reference timing and sends the RAR to the UE. The target base station receives the random access preamble sent with dedicated resources and / or preamble index, and identifies that the transfer of accurate reference timing should be performed. The target base station obtains some other accurate reference timing-related information required to perform the transfer of accurate reference timing, such as TSCAI, from the core network (e.g., 5GC) or the source base station.

[0061] In one embodiment, the accurate reference timing may be delivered together with the RAR message or carried in the RAR message. In another embodiment, the target base station may perform the delivery of the accurate reference timing by means of SI broadcast. The UE may obtain the accurate reference timing by receiving the RAR or SI from the target base station.

[0062] If the target base station does not support accurate timing reference delivery services, the access may be denied.

[0063] For contention-based random access scenarios:

[0064] refer to Figure 4 In step 0, the source base station sends an RRCConnectionReconfiguration message to the UE, instructing the UE to perform contention-based random access. The RRCConnectionReconfiguration message may be a conventional operation, such as a currently standardized operation; or, the RRCConnectionReconfiguration message may instruct the UE to send a random access preamble, which uses time-frequency resources dedicated to time-sensitive services, etc. The dedicated time-frequency resources mentioned above can be allocated to UEs supporting time-sensitive services to transmit random access preambles. This allocation can be configurable and / or currently standardized, etc.

[0065] In step 1, the UE sends a random access preamble to the target base station. The UE may select the random access preamble and send it to the target base station as specified in the random access procedure initiated by the handover process in the NR standard; or the UE may send the random access preamble using dedicated time-frequency resources for time-sensitive services. Dedicated time-frequency resources may be configured or standardized for time-sensitive services.

[0066] The corresponding behavior may be that the UE receives a configuration instructing the UE to perform contention-based random access, and the UE selects the dedicated time-frequency resources to send the random access preamble; or, the UE receives a configuration instructing the UE to perform contention-based random access specific to time-sensitive services, and the UE selects the dedicated time-frequency resources to send the random access preamble; or, the dedicated time-frequency resources are indicated in the RRCConnectionReconfiguration message, and the UE uses the indicated time-frequency resources to send the random access preamble.

[0067] In step 2, the target base station sends the RAR to the UE. The target base station may send the RAR message to the UE in accordance with the conventional provisions in the 3GPP standard. Alternatively, the target base station receives the random access preamble sent using the dedicated time-frequency resource, and obtains information related to the accurate reference timing in the behavior described in the contention-based random access procedure, generates an accurate reference timing message, and carries it in the RAR message and sends it to the UE.

[0068] The target base station can send information related to the accurate reference timing to the UE by broadcasting SI related to the accurate reference timing, such as SIB9. The target base station can obtain information related to the accurate reference timing from the core network (e.g., 5GC) or the source base station, or as specified in the 3GPP standard. Then, the target base station broadcasts SI related to the accurate reference timing. The UE receives the SI and obtains the accurate reference timing information of the target base station.

[0069] The target base station may postpone sending the message related to the accurate reference timing, and send the message related to the accurate reference timing in message 4 (step 4b).

[0070] Step 3, the UE sends message 3 and accurate reference timing to the target base station. An accurate reference timing request and / or TSCAI may be sent from the UE to the target base station. The accurate reference timing request and / or TSCAI may be encapsulated, carried or carried in message 3.

[0071] In step 4, the target base station sends message 4 to the UE. The message related to accurate reference timing delivery may be sent to the UE in message 4. The generation of the message related to accurate reference timing delivery may reuse the method described in the above steps, including contention-free random access and embodiment 1.

[0072] Continue to execute the remaining steps of the handover procedure. The UE sends an RRCConnectionReconfigurationComplete message to the target base station (step 5), performs path switching and context exchange, etc.

[0073] Example 3

[0074] Figure 5 A flowchart of a method for time synchronization during a handover according to a third embodiment of the present application is shown. The UE handover is performed between a source base station (e.g., a source gNB) and a target base station (e.g., a target gNB). The accurate reference timing request and response can be transmitted through a user plane data exchange operation during the handover, such as Figure 5 When the UE successfully performs random access and connects to the target base station and enters the RRC_CONNECTED state but does not complete the Path Switch operation, the source base station forwards the data from the core network (such as 5GC) to the target base station, and then the data can be sent to the UE, such as Figure 5 Similarly, the End Marker from the core network can be sent to the target base station through the source base station after the path switching operation is completed.

[0075] The reference timing request and related information may be encapsulated in user data (step 1b) and / or an EndMarker message (step 2b) and sent from the source base station to the target base station. The target base station may send the accurate reference timing to the UE by forwarding the user data to the UE (step 1c) and / or by SI broadcast (step 2c).

[0076] In the following description, it is assumed that 1) both the UE and the source base station support time-sensitive services; 2) the UE is connected to the source base station and is in the RRC_CONNECTED state; 3) the UE is performing measurements and measurement reports; 4) the handover procedure is triggered; and 5) the UE successfully accesses the target base station and enters the RRC_CONNECTED state.

[0077] After the random access procedure initiated during the handover process is successfully completed, the UE connects to the target base station and enters the RRC_CONNECTED state. The source base station forwards the user data that should be sent to the UE and is received from the core network (e.g., 5GC) to the target base station. As shown in step 1b, an accurate reference timing request and related information can be carried in the above-mentioned user data and sent to the target base station. As shown in steps 2a and 2b, the same operation can also be performed using an End Marker message. That is, an accurate reference timing request and related messages can be included in an End Marker message and sent to the target base station.

[0078] The target base station delivers accurate reference timing by packaging information related to accurate reference timing in a user data packet or an End Marker message and sending it to the UE, such as Figure 5 Alternatively, the target base station may broadcast SI associated with the accurate reference timing, such as Figure 5 Step 2c shown.

[0079] Example 4

[0080] A serving base station serving the UE obtains neighboring cell information about whether the neighboring cell meets the requirements of accurate reference timing, and configures the UE in the RRC_CONNECTED state to perform time-sensitive service-related measurements on neighboring cells that support accurate reference timing services or time-sensitive services. The measurement report related to the time-sensitive service may include the cell ID that supports both the time-sensitive service and meets the switching conditions. The serving base station determines which cell to switch to based on the measurement report related to the time-sensitive service.

[0081] Measurement reports related to time-sensitive services can be periodic and event-triggered. For event-triggered measurement reports related to time-sensitive services, the serving base station can configure thresholds for the UE. If one of the events occurs, the measurement variable (e.g., RSRP / RSRQ / SINR) reaches or exceeds the (pre)configured / standardized threshold.

[0082] A triggering event for a switching process related to a time-sensitive service may be defined. If the measurement result is greater than, greater than or equal to threshold a (for event a) and / or less than, less than or equal to threshold b (for event b), the corresponding event will be triggered, that is, the UE will perform measurement reporting related to the time-sensitive service.

[0083] Alternatively, the UE can be configured to perform periodic measurements and send reports to the serving base station as specified in the 3GPP standard. The serving base station then selects a candidate cell to be switched to based on the measurement report and neighboring cell information about whether the neighboring cell supports time-sensitive services or meets time synchronization accuracy requirements.

[0084] The base station may broadcast SI related to the accurate reference timing by broadcasting a system information block (eg, SIB9). A UE in the RRC_IDLE state and the RRC_INACTIVE state receives SI during a random access process and performs cell (re)selection based on the obtained SI.

[0085] Figure 6The flowchart of the cell (re)selection method according to the fourth embodiment of the present application is shown. Assume that 1) both the UE and the serving gNB support time-sensitive services; 2) the UE is connected to the serving gNB and is in the RRC_CONNECTED state; 3) the serving cell determines whether to switch and which cell to switch to.

[0086] a) The UE receives the measurement configuration.

[0087] The serving base station obtains neighboring cell information from the neighboring cell (step 0a) or / and the core network (e.g., 5GC) (step 0b), which at least includes whether time-sensitive services are supported. The configuration of measurement and reporting can be a conventional configuration message as specified in the 3GPP standard. In another embodiment, cell information (e.g., cell ID supporting time-sensitive services) can be included in the configuration message of the measurement and reporting.

[0088] b) UE performs measurements and reports.

[0089] In one embodiment, the UE in the RRC_CONNECTED state receives the measurement and reporting configuration from the serving cell (step 1), and performs measurement and reporting according to the existing mechanism described in the 3GPP standard. In another embodiment, the UE performs measurement on the neighboring cell supporting the time-sensitive service indicated in the measurement configuration message (step 1).

[0090] The UE periodically sends the measurement results to the serving cell and / or the sending of the measurement results is triggered by related events (step 2). Events for measurement reports related to time-sensitive services can be defined to trigger the UE to perform measurement reporting, and related parameters (eg, thresholds) can be configured for the UE.

[0091] c) The serving base station receives the measurement report, then makes a handover decision and performs the handover process.

[0092] In one embodiment, the measurement report includes cell information (e.g., cell ID) supporting time-sensitive services, and the serving base station determines which cell to switch to based on the measurement report (step 3). In another embodiment, the serving base station makes a decision on whether to switch based on the measurement report received from the UE and the neighboring cell information obtained from the neighboring cell or / and the core network (e.g., 5GC) (step 3).

[0093] Figure 7 A block diagram of an example system 700 for wireless communication according to an embodiment of the present application is shown. The embodiments described herein may be implemented into the system using any suitably configured hardware and / or software. Figure 7A system 700 is shown that includes a radio frequency (RF) circuit 710, a baseband circuit 720, a processing unit 730, a memory / storage device 740, a display 750, a camera 760, a sensor 770, and an input / output (I / O) interface 780, which are coupled to each other as shown.

[0094] The processing unit 730 may include circuits such as, but not limited to, one or more single-core or multi-core processors. The processor may include any combination of general-purpose processors and special-purpose processors (e.g., graphics processors and application processors). The processor may be coupled to a memory / storage device and configured to execute instructions stored in the memory / storage device to enable various applications and / or operating systems to run on the system.

[0095] The baseband circuit 720 may include circuits, such as but not limited to one or more single-core or multi-core processors. The processor may include a baseband processor. The baseband circuit may handle various wireless control functions that enable communication with one or more radio networks via RF circuits. The radio control functions may include but are not limited to signal modulation, encoding, decoding, radio frequency shifting, etc. In some embodiments, the baseband circuit may provide communications compatible with one or more wireless technologies. For example, in some embodiments, the baseband circuit may support communications with 5G NR, LTE, Evolved Universal Terrestrial Radio Access Network (EUTRAN) and / or other wireless wide area networks (WMAN), wireless local area networks (WLAN), wireless personal area networks (WPAN). An embodiment in which the baseband circuit is configured to support wireless communications of more than one wireless protocol may be referred to as a multi-mode baseband circuit. In various embodiments, the baseband circuit 720 may include circuits for operating with signals that are not strictly considered to be in the baseband frequency. For example, in some embodiments, the baseband circuit may include circuits for operating with signals having an intermediate frequency, which is between the baseband frequency and the radio frequency.

[0096] The RF circuit 710 can use modulated electromagnetic radiation to achieve communication with a wireless network through a non-solid medium. In various embodiments, the RF circuit may include switches, filters, amplifiers, etc. to facilitate communication with the wireless network. In various embodiments, the RF circuit 710 may include circuits for operating with signals that are not strictly considered to be in radio frequency. For example, in some embodiments, the RF circuit may include circuits for operating with signals having an intermediate frequency, which is between the baseband frequency and the radio frequency.

[0097] In various embodiments, the transmitter circuits, control circuits, or receiver circuits discussed above with respect to user equipment, eNBs, or gNBs may be implemented in whole or in part in one or more of the RF circuits, baseband circuits, and / or processing units. As used herein, "circuitry" may refer to, may be part of, or include an application specific integrated circuit (ASIC), an electronic circuit that executes one or more software or firmware programs, a processor and / or memory (shared, dedicated, or group), a combined logic circuit, and / or other suitable hardware components that provide the described functionality. In some embodiments, the electronic device circuit system may be implemented in one or more software or firmware modules, or the functionality associated with the circuit system may be implemented by one or more software or firmware modules. In some embodiments, some or all of the components of the baseband circuit, processing unit, and / or memory / storage device may be implemented together on a system-on-chip (SOC).

[0098] The memory / storage device 740 can be used to load and store data and / or instructions for the system, for example. The memory / storage device of an embodiment may include any combination of suitable volatile memory (e.g., dynamic random access memory (DRAM)) and / or non-volatile memory (e.g., flash memory). In various embodiments, the I / O interface 780 may include one or more user interfaces and / or peripheral component interfaces, and the one or more user interfaces are designed to enable a user to interact with the system, and the peripheral component interface is designed to enable a peripheral component to interact with the system. The user interface may include, but is not limited to, a physical keyboard or keypad, a touch pad, a speaker, a microphone, etc. The peripheral component interface may include, but is not limited to, a non-volatile memory interface, a universal serial bus (USB) interface, an audio jack, and a power interface.

[0099] In various embodiments, the sensor 770 may include one or more sensing devices for determining environmental conditions and / or location information related to the system. In some embodiments, the sensor may include, but is not limited to, a gyroscope sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of or interact with a baseband circuit and / or an RF circuit to communicate with a component of a positioning network (e.g., a global positioning system (GPS) satellite). In various embodiments, the display 750 may include displays such as a liquid crystal display and a touch screen display. In various embodiments, the system 700 may be a mobile computing device, such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smart phone, etc. In various embodiments, the system may have more or fewer components and / or different architectures. Where appropriate, the method described herein may be implemented as a computer program. The computer program may be stored on a storage medium such as a non-transitory storage medium.

[0100] Some embodiments of the present application are combinations of “techniques / processes” that can be adopted in 3GPP specifications to develop terminal products.

[0101] It will be appreciated by those skilled in the art that each unit, algorithm and step described and disclosed in the embodiments of the present application are implemented using electronic hardware or a combination of software and electronic hardware for a computer. Whether these functions are run in hardware or software mode depends on the design requirements of the application conditions and technical solutions. Those skilled in the art can use different ways to implement the functions of each specific application, and this implementation should not exceed the scope of the present application. It will be appreciated by those skilled in the art that the working process of the system, device and unit in the above-mentioned embodiments can be referred to, because the working process of the above-mentioned system, device and unit is basically the same. For ease of description and brevity, these working processes will not be described in detail.

[0102] It should be understood that the systems, devices and methods disclosed in the embodiments of the present application can be implemented in other ways. The embodiments described above are merely illustrative. The division of units is based only on logical functions, and other divisions exist during implementation. Multiple units or components can be combined or integrated into another system. Some features can also be omitted or skipped. On the other hand, the coupling, direct coupling or communication coupling shown or discussed can be indirect coupling through some interfaces, devices or units or electrical, mechanical or other forms of communication coupling.

[0103] The units described as separate components may or may not be physically separate. The units shown may or may not be physical units, i.e., they may be located in one place or distributed over multiple network units. Some or all of the units may be used depending on the purpose of the embodiment. In addition, the functional units in various embodiments may be integrated into one processing unit, or may be physically independent, or two or more units may be integrated into one processing unit.

[0104] If the software functional unit is implemented and sold or used as an independent product, it can be stored in a readable storage medium in a computer. Based on such an understanding, the technical solution proposed in the present application can be essentially or partially implemented in the form of a software product. Alternatively, a part of the technical solution that is beneficial to the prior art can be implemented in the form of a software product. The software product in the computer is stored in a storage medium, including multiple commands for a computing device (such as a personal computer, a server or a network device) to run all or part of the steps disclosed in the embodiment of the present application. The storage medium includes a USB disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a floppy disk or other media capable of storing program code.

[0105] While the present application has been described in connection with what are considered to be the most practical and preferred embodiments, it is to be understood that the application is not limited to the disclosed embodiments, but is intended to cover various arrangements pursuant to the broadest interpretation of the appended claims.

[0106] like Figure 8 As shown, the switching process mentioned in the present application at least includes a switching preparation phase, a switching execution phase and a switching completion phase.

[0107] In the handover preparation phase, the UE performs measurements and reports according to the measurement and reporting configuration received from the base station or according to relevant standard specifications. When the handover conditions are met, the source base station sends a handover request to a selected or candidate target base station. If the candidate target base station accepts the handover request, the target base station sends a handover request confirmation (positive response) to the source base station. Then, the RAN handover begins.

[0108] According to the configuration from the source base station, such as RrcConnectionReconfiguration, the UE performs a random access procedure initiated by the handover process (e.g., contention-free random access or contention-based random access) during the handover execution phase. Before completing the path switch, the remaining data from the core network will be forwarded by the source base station to the target base station.

[0109] Then, the path switch is performed in the handover completion phase. A path switch request is sent from the target base station to the core network, and once it is confirmed (positive response), data can flow from the UE through the target base station to release the UE context.

Claims

1. A time synchronization method for performing a handover of a user equipment UE between a source base station and a target base station in a cellular wireless communication system, characterized in that: The method is performed by the target base station and includes: Receiving or acquiring information related to time-sensitive communication (TSC) including a request for accurate reference timing during the handover process; and In response to the accurate reference timing request, delivering accurate reference timing to the UE during the handover process; The accurate reference timing request is carried or carried in a handover command, and a bit or a field having several bits in the handover command is used to indicate that the target base station should support the accurate reference timing or perform delivery of the accurate reference timing; The information related to the TSC is obtained through an end marker message during the path switching operation in the switching process.

2. The method according to claim 1, wherein: The information related to the TSC is obtained during the handover preparation phase.

3. The method according to claim 1, further comprising: In response to the switching command, a switching request confirmation message is sent, and an accurate reference timing response message is carried or loaded in the switching request confirmation message, and the accurate reference timing is delivered to the UE by the source base station.

4. The method according to claim 1, further comprising: Broadcast system information SI related to the accurate reference timing to deliver the accurate reference timing to the UE in a broadcast manner.

5. The method according to claim 1, further comprising: According to the information related to the TSC, it is determined whether an accurate reference timing requirement of a time-sensitive service used by the UE is met.

6. The method according to claim 1, wherein: The information related to the TSC is obtained in a random access procedure initiated during a handover process.

7. The method according to claim 1, wherein: In the acquisition step, the information related to TSC includes the accurate reference timing request indicated by a dedicated random access preamble or a dedicated time-frequency resource for sending a random access preamble; or, the information related to TSC includes the accurate reference timing request carried or carried in a random access preamble packet; or, the information related to TSC includes the accurate reference timing request carried or carried in message 3.

8. The method according to claim 1, wherein: In the delivering step, the accurate reference timing is delivered to the UE via a random access response RAR message; or, the accurate reference timing is delivered to the UE via message 4.

9. The method according to claim 1, wherein: The TSC-related information is obtained through a user plane data exchange operation after the UE successfully performs a handover and before a path switching operation.

10. The method according to claim 9, wherein: In the delivering step, the accurate reference timing is delivered by the target base station to the UE, and the accurate reference timing is encapsulated in user data.

11. A time synchronization method for executing a handover of a user equipment UE between a source base station and a target base station in a cellular wireless communication system, characterized in that: The method is performed by the UE and includes: Receiving an accurate reference timing sent by the target base station during the handover process; and Synchronize with the target base station using the accurate reference timing; The accurate reference timing request is carried or carried in a handover command, and a bit or a field having several bits in the handover command is used to indicate that the target base station should support the accurate reference timing or perform delivery of the accurate reference timing; The information related to the time-sensitive communication TSC is obtained through an end marker message during the path switching operation in the switching process.

12. The method according to claim 11, wherein: The accurate reference timing is received during the handover preparation phase.

13. The method according to claim 11, wherein: The accurate reference timing is received in a random access procedure initiated by a handover process.

14. The method according to claim 11, wherein: The requirement for accurate reference timing delivery is indicated by a dedicated random access preamble sent to the target base station or a dedicated time-frequency resource for sending a random access preamble to the target base station; or, the requirement for accurate reference timing delivery is indicated by a random access preamble sent to the target base station.

15. The method according to claim 11, wherein: In the receiving step, the accurate reference timing is received through a random access response RAR message; or, the accurate reference timing is received through message 4; or, the accurate reference timing is received by receiving broadcast information; or, the accurate reference timing is received through radio resource control RRC unicast signaling from the source base station to the UE; or, the accurate reference timing is received through a MAC control element MAC CE.

16. The method according to claim 11, wherein: In the receiving step, the accurate reference timing is received by receiving user data sent from the target base station after the UE successfully switches to the target base station; or, the accurate reference timing is received by receiving a system information block broadcasted by the target base station when performing a path switching operation.

17. A base station, comprising: A processor configured to call and run program instructions stored in a memory to execute the method according to any one of claims 1 to 10.

18. A user equipment UE, comprising: A processor configured to call and run program instructions stored in a memory to execute the method according to any one of claims 11 to 16.

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