Method and apparatus for controlling sending of SR in LTM handover

Abstract

Disclosed in the present application are a method and apparatus for controlling the sending of an SR in an LTM handover. The method comprises: receiving RRC signaling sent by a source cell, wherein the RRC signaling at least comprises configuration information of a first candidate target cell, and the configuration information of the first candidate target cell comprises a first execution condition; as a response to the first execution condition being satisfied, executing an LTM cell handover; and initiating a process of sending an SR to the target cell, wherein the initiation of the process of sending the SR to the target cell depends on whether the executed LTM cell handover is an RACH-based LTM cell handover or an RACH-free LTM cell handover. The present application can better support a conditional RACH-free LTM cell handover, thereby avoiding resource waste, and reducing the time delay of the LTM cell handover.

Description

A method and apparatus for controlling SR transmission during LTM handover

[0001] This application claims priority to Chinese Patent Application No. 202410519057.6, filed on April 26, 2024, entitled "A method and apparatus for controlling SR transmission during LTM handover", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to transmission methods and apparatus in wireless communication systems, and more particularly to methods and apparatus in LTM cell handover. Background Technology

[0003] With the continuous development of wireless communication, the requirements for mobility are becoming increasingly stringent, such as shorter downtime. The 3rd Generation Partner Project (3GPP) RAN (Radio Access Network) #94e meeting decided to study Layer 1 (L1) / L2 (L2) triggered mobility (LTM) in the "Further NR mobility enhancements" work item (WI).

[0004] Layer 3 (L3) mobility has been developed in several versions. The evolution of conditional handover (CHO) and other conditional migration procedures (CPAC, SCPAC) also allows for execution without prior signaling interaction with the source cell, thus achieving high robustness. LTM, introduced in Rel-18, provides shorter downtime, but its robustness is not as good as conditional L3 migration procedures. In Rel-19, enhancements should be specified so that the system can benefit from both high robustness and short downtime. Summary of the Invention

[0005] When a UE performs an existing L3 handover, a random access procedure is triggered, which is detrimental to UE service continuity. However, while LTM handover can shorten the interruption time, it may affect robustness. Therefore, it is necessary to enhance LTM cell handover, especially the robustness of LTM cell handover without RACH.

[0006] To address the aforementioned problems, this invention provides a mobility solution. While the NR system is used as an example in the problem description, this invention is also applicable to scenarios such as LTE (Long-Term Evolution) systems, achieving similar technical effects. Furthermore, although this invention provides a specific implementation for LTM, it can also be used in scenarios such as PSCell modifications, achieving similar technical effects. Furthermore, although this invention is initially intended for the Uu air interface, it can also be used for the PC5 interface, achieving similar technical effects. Furthermore, although this invention is initially intended for terminal-to-base station scenarios, it is also applicable to V2X (Vehicle-to-Everything) scenarios, communication scenarios between terminals and relays, and between relays and base stations, achieving similar technical effects. Furthermore, although this invention is initially intended for terminal-to-base station scenarios, it is also applicable to IAB (Integrated Access and Backhaul) communication scenarios, achieving similar technical effects. Furthermore, although this invention was initially intended for terrestrial network (TN) scenarios, it is also applicable to non-terrestrial network (NTN) communication scenarios, achieving similar technical effects to those in TN scenarios. In addition, using a unified solution across different scenarios helps reduce hardware complexity and cost.

[0007] As an example, the interpretation of the terminology in this invention is based on the definitions in the 3GPP specification protocol TS36 series.

[0008] As an example, the interpretation of the terminology in this invention is based on the definitions in the 3GPP specification protocol TS38 series.

[0009] As an example, the interpretation of terms in this invention is based on the definitions in the 3GPP specification protocol TS37 series.

[0010] It should be noted that, unless otherwise specified, embodiments and features in any node of the present invention can be applied to any other node. Furthermore, unless otherwise specified, embodiments and features in any embodiment of the present invention can be arbitrarily combined with each other.

[0011] To address the aforementioned technical problems, this invention discloses a method for a first node in cell handover, comprising: receiving RRC signaling sent by a source cell, the RRC signaling including configuration information of at least a first candidate target cell; the configuration information of the first candidate target cell including a first execution condition;

[0012] In response to the fulfillment of the first execution condition, an LTM cell handover is performed;

[0013] The process of initiating the sending of SR to the first candidate target cell depends on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover.

[0014] The meaning of "the process of initiating the sending of SR to the first candidate target cell depends on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover" is that the process of initiating the sending of SR to the first candidate target cell is performed only when the LTM cell handover performed is a RACH-free LTM cell handover.

[0015] In the technical solution provided by this invention, the first node, using the configuration information of the received first candidate target cell, initiates a process of sending an SR to the first candidate target cell when performing an LTM cell handover without RACH, under the condition that the first execution condition is met. This solution eliminates the need to initiate a random access procedure to the first candidate target cell, thus reducing latency.

[0016] Furthermore, the candidate target cell for LTM cell handover (e.g., the first candidate target cell) does not need to reserve physical downlink control channel (PDCCH) resources for terminal equipment (such as the first node) capable of performing LTM without RACH for a long time, which can save downlink resources and also help improve the PDCCH blind detection performance of other terminal equipment.

[0017] As an example, the problem to be solved by the present invention includes: how to control SR transmission during LTM cell handover.

[0018] As an example, whether to send an SR depends on whether the UE is performing a RACH-based LTM cell handover or a RACH-free LTM cell handover.

[0019] As an example, the advantages of the above method include: no need to listen to PDCCH resources in the candidate target cell, no need to send downlink control information to the candidate target cell, which helps to improve the reception performance of downlink control information of other nodes and improve resource utilization.

[0020] As an example, the advantages of the above method include: avoiding triggering a random access procedure on the first candidate target cell and reducing handover latency.

[0021] As an example, the advantages of the above method include: LTM handover is performed only when the first execution condition is met, which increases the success probability of LTM cell handover.

[0022] As an example, the advantages of the above method include: the UE autonomously performs LTM, which helps to shorten the latency of SR being sent.

[0023] As an example, the advantages of the above method include: improving UE service continuity.

[0024] As an example, whether the LTM cell handover is RACH-based LTM or RACH-free LTM depends on the RRC signaling.

[0025] As an example, the process of initiating the sending of SR to the first candidate target cell includes: attempting to send SR to the first candidate target cell.

[0026] As an example, the transmission of the SR is independent of whether there is data to be transmitted.

[0027] As an example, the transmission of the SR is independent of whether there is a Medium Access Control (MAC) Control Element (CE).

[0028] As an example, whether or not the SR is sent is independent of the data to be transmitted and the MAC CE.

[0029] As an example, the transmission of the SR does not depend on whether there is data to be transmitted.

[0030] As an example, the transmission of the SR does not depend on whether there is a pending MAC CE.

[0031] As an example, the transmission of the SR is independent of whether there is data to be transmitted and independent of whether there is a MAC CE to be transmitted.

[0032] As an example, the SR is not associated with any data.

[0033] As an example, the SR is not associated with any MAC CE.

[0034] As an example, the advantages of SR not relying on data transmission include: SR can be sent as early as possible without adding latency by waiting for data to be sent.

[0035] As an example, the sending of the SR to the first candidate target cell is performed after the LTM cell handover begins.

[0036] As an example, the sending of the SR to the first candidate target cell is performed before the LTM cell handover is completed.

[0037] As an example, the first node does not require listening to the PDCCH of the first candidate target cell before the SR is sent.

[0038] As an example, in response to receiving the PDCCH scheduling of the first candidate target cell, the process of sending the SR to the first candidate target cell is cancelled.

[0039] As an example, in response to receiving a PDCCH schedule from any target cell, the process of sending an SR to the first candidate target cell is cancelled.

[0040] As an example, the SR is the first SR sent to the first candidate target cell.

[0041] As an example, the SR is the first signal sent to the first candidate target cell.

[0042] According to one aspect of the present invention, sending an SR to the first candidate target cell includes: sending the SR to the first candidate target cell depends on the synchronization of the first candidate target cell.

[0043] The present invention can effectively increase the probability of SR being successfully received, thereby improving the handover success rate.

[0044] According to one aspect of the present invention, a timer is started along with the process of initiating the transmission of SR to the first candidate target cell; upon the expiration of the timer, the process of transmitting SR to the first candidate target cell is cancelled, and the execution of RACH-based LTM is rolled back.

[0045] As an example, the fallback execution of RACH-based LTM only includes Contention Based Random Access (CBRA) LTM.

[0046] As an example, the advantages of the above method include: stability and reliability, resource saving, and no constraints on switching time.

[0047] As a variation, the fallback execution of RACH-based LTM includes CBRA-based LTM and Contention-Free Random Access (CFRA)-based LTM. The advantages of these methods include higher flexibility and reduced handover latency.

[0048] According to one aspect of the invention, the method includes: during the operation of the timer, after sending an SR to the first candidate target cell, stopping the timer; wherein the SR is the first uplink signal sent by the first node to the first candidate target cell.

[0049] The solution of this invention helps terminal devices reduce the resource overhead of maintenance timers.

[0050] According to one aspect of the present invention, sending an SR to the first candidate target cell includes: updating a counter when sending the SR fails; resetting the counter when the counter reaches a preset value, canceling the process of sending the SR to the first candidate target cell, and reverting to RACH-based LTM; wherein the counter is used to record the number of SR transmission failures.

[0051] The solution of this invention helps to reduce the probability of LTM handover failure.

[0052] According to one aspect of the invention, in response to the failure to send an SR to the first candidate target cell, a counter is updated; when the counter reaches a preset value, the counter is reset, and the process of sending an SR to the first candidate target cell is canceled, and the RACH-based LTM is rolled back.

[0053] The present invention provides candidate SR resources before sending the SR, which is beneficial for successful SR transmission.

[0054] According to one aspect of the invention, whether the LTM cell handover is RACH-based LTM or RACH-free LTM depends on the RRC signaling.

[0055] According to one aspect of the invention, an SR is sent to the first candidate target cell on one of at least one SR resources; wherein the configuration information of the first candidate target cell includes the at least one candidate SR configuration, and each candidate SR configuration is associated with at least one SR resource.

[0056] According to one aspect of the present invention, an RRC reconfiguration message for the first candidate target cell is received, the RRC reconfiguration message including deleting the context information of the source cell and retaining the configuration information of at least the first candidate target cell.

[0057] According to one aspect of the invention, the first execution condition includes: the quality of the first candidate target cell is better than a given threshold; and the configuration information of the first candidate target cell includes the given threshold.

[0058] The present invention enables the terminal device to determine the LTM switching mode after receiving RRC signaling, which helps to reduce process complexity.

[0059] According to one aspect of the present invention, after sending an SR to the first candidate target cell, listening to the PDCCH includes: receiving scheduling information, and determining, in response to receiving the scheduling information, that the LTM cell handover is complete.

[0060] To address the aforementioned technical problems, this invention discloses a method for a second node in cell handover, comprising: receiving a signal relay (SR), wherein the SR depends on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover; the meaning of the SR depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the SR is sent only when the LTM cell handover being performed is a RACH-free LTM cell handover; wherein the SR is triggered by the satisfaction of a first execution condition, the first execution condition being included in the configuration information of a first candidate target cell, and the configuration information of the first candidate target cell being included in the RRC signaling from the source cell to the sender of the SR.

[0061] According to one aspect of the present invention, the configuration information of the first candidate target cell includes at least one candidate SR configuration, each of the candidate SR configurations being associated with at least one SR resource; receiving the SR includes: receiving the SR on one of the at least one SR resources.

[0062] According to one aspect of the invention, whether the LTM cell handover is RACH-based LTM or RACH-free LTM depends on the RRC signaling.

[0063] According to one aspect of the invention, the reception of the SR triggers the second node to schedule the sender of the SR.

[0064] To address the aforementioned technical problems, this invention discloses a method for a third node in cell handover, comprising: sending RRC signaling to a first node, the RRC signaling including configuration information of at least a first candidate target cell; the configuration information of the first candidate target cell including a first execution condition; wherein, when the first execution condition is met, the first node performs an LTM cell handover; sending a SR to the first candidate target cell, wherein sending the SR to the first candidate target cell depends on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover; the meaning of sending the SR to the first candidate target cell depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the SR is sent only when the LTM cell handover being performed is a RACH-free LTM cell handover.

[0065] According to one aspect of this application, whether the LTM cell handover is RACH-based LTM or RACH-free LTM depends on the RRC signaling.

[0066] To address the aforementioned technical problems, this invention discloses a first node for cell handover, comprising: a receiver for receiving RRC signaling sent by a source cell, the RRC signaling including configuration information of at least a first candidate target cell; the configuration information of the first candidate target cell including a first execution condition; a processor for performing LTM cell handover as a response to the first execution condition being met; and a transmitter for initiating a process of sending a scheduling request (SR) to the first candidate target cell, wherein the process of initiating the process of sending the SR to the first candidate target cell depends on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover; wherein, the meaning of the process of initiating the process of sending the SR to the first candidate target cell depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the process of initiating the process of sending the SR to the first candidate target cell is executed only when the LTM cell handover being performed is a RACH-free LTM cell handover.

[0067] To address the aforementioned technical problems, this invention discloses a second node for cell handover, comprising: a receiver, receiving a signal transfer (SR), wherein the SR depends on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover; the meaning of the SR depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the SR is sent only when the LTM cell handover being performed is a RACH-free LTM cell handover; wherein the SR is triggered by the satisfaction of a first execution condition, the first execution condition being included in the configuration information of a first candidate target cell, and the configuration information of the first candidate target cell being included in the RRC signaling from the source cell to the sender of the SR.

[0068] To address the aforementioned technical problems, this invention discloses a third node for cell handover, comprising:

[0069] The transmitter sends RRC signaling to a first node, the RRC signaling including configuration information of at least a first candidate target cell; the configuration information of the first candidate target cell includes a first execution condition; wherein, when the first execution condition is met, the first node performs an LTM cell handover; and sends an SR to the first candidate target cell, the sending of the SR to the first candidate target cell depending on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover;

[0070] The meaning of sending an SR to the first candidate target cell depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the SR is sent only when the LTM cell handover being performed is a RACH-free LTM cell handover.

[0071] As an example, compared with conventional solutions, the present invention has the following advantages:

[0072] (1) Determining whether to send an SR based on whether the UE is performing a RACH-based LTM cell handover or a RACH-free LTM cell handover has many advantages;

[0073] (2) It saves PDCCH resources and helps improve PDCCH reception performance;

[0074] (3) Avoid triggering a random access procedure on the first candidate target cell to reduce handover latency;

[0075] (4) LTM handover is only performed when the first execution condition is met, which increases the probability of LTM cell success, which is beneficial to improving the robustness of LTM and avoiding dropped calls;

[0076] (5) The UE autonomously performs LTM, which helps to shorten the latency of LTM cell handover;

[0077] (6) It helps improve UE service continuity. Attached Figure Description

[0078] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0079] Figure 1 shows a schematic diagram of the LTM switching process according to an embodiment of the present invention;

[0080] Figure 2 shows a schematic diagram of a network architecture according to an embodiment of the present invention;

[0081] Figure 3 shows a schematic diagram of an embodiment of a wireless protocol architecture for the user plane and control plane according to an embodiment of the present invention;

[0082] Figure 4 shows a schematic diagram of the hardware modules of a communication device according to an embodiment of the present invention;

[0083] Figure 5 shows a flowchart of wireless signal transmission according to an embodiment of the present invention;

[0084] Figure 6 shows a flowchart of wireless signal transmission according to another embodiment of the present invention;

[0085] Figure 7 shows a flowchart of wireless signal transmission according to yet another embodiment of the present invention;

[0086] Figure 8 illustrates a flowchart of wireless signal transmission according to yet another embodiment of the present invention;

[0087] Figure 9 illustrates yet another wireless signal transmission flowchart according to an embodiment of the present invention;

[0088] Figure 10 shows a structural block diagram of a processing device for a first node according to an embodiment of the present invention;

[0089] Figure 11 shows a structural block diagram of a processing device for a second node according to an embodiment of the present invention;

[0090] Figure 12 shows a structural block diagram of a processing device for a third node according to an embodiment of the present invention. Detailed Implementation

[0091] As mentioned in the background section, existing technologies for mobility management, such as cell handover, employ various technical implementations, including L3 handover and L1 / L2 handover below L3. The development of Conditional Handover (CHO) and other conditional migration procedures (CPAC, SCPAC) allows handover processes to be performed without prior signaling interaction with the source cell, achieving high robustness. While LTM technology introduced in Rel-18 provides shorter downtime, its robustness is inferior to conditional L3 mobility procedures. Enhancing this functionality during NR evolution is necessary so that wireless communication systems can benefit from both high robustness and short downtime.

[0092] Currently, network devices can provide terminal devices (such as UEs) with one or more candidate configurations, each of which can include one or more cells. The network device can then control the terminal device to change between these candidate configurations via L1 or L2 signaling, also known as cell change control signaling, to achieve serving cell change. This process can be called the LTM process.

[0093] The general LTM process is as follows: First, the terminal device in RRC connection state reports the measurement results to the source cell. If the terminal device supports LTM, the source cell can send an LTM cell handover request to a candidate target cell. After the candidate target cell sends an LTM cell handover request response to the source cell, and sends the configured information of the corresponding LTM candidate target cell to the source cell, the source cell can send RRC reconfiguration information to the terminal device. The RRC reconfiguration information may carry the configuration information of the LTM candidate target cell.

[0094] After receiving the configuration information of the LTM candidate target cells, the terminal device sends an RRC reconfiguration complete message to the source cell. Then, the terminal device performs downlink and uplink synchronization for each candidate target cell.

[0095] In the process of uplink synchronization for each candidate target cell, if the RRC reconfiguration information indicates that the timing advance (TA) is measured by the terminal device itself, the terminal device can measure the timing advance of the source cell and determine the timing advance of the candidate target cell based on the reception time difference between the source cell and the candidate cell; or, the source cell triggers CFRA through PDCCH order to obtain the timing advance of the candidate target cell, the terminal device initiates CFRA to the candidate target cell to obtain the timing advance of the candidate target cell, and then the source cell determines the validity of the timing advance.

[0096] After uplink synchronization is complete, the terminal device performs L1 measurements on the source cell and candidate target cells, obtains the L1 measurement results, and then reports the L1 measurement results to the source cell. After the terminal device reports the L1 measurement results to the source cell, the source cell can determine the candidate target cell based on the L1 measurement results. The source cell then issues an LTM handover command to the terminal device.

[0097] The LTM handover instruction can be a MAC CE. The MAC CE can contain at least the following information: TA, Transmission Configuration Indication State (TCI State) sequence number (IDentity, ID), CFRA resource information, and configuration information identifier of the LTM candidate primary cell. For the TA, if the TA obtained by the terminal device before the source cell determined that it is still valid, then the TA can be included in the MAC CE.

[0098] Furthermore, the terminal device disconnects from the source cell and initiates a random access procedure to the candidate target cell. When the terminal device receives a MAC CE, if the MAC CE carries a TA, or the terminal device detects the TA itself, then the terminal device initiates a handover without random access to the candidate target cell. That is, the terminal device sends an uplink signaling message or the first uplink data packet to the candidate target cell to indicate that it has accessed the candidate target cell, thereby completing the LTM cell handover.

[0099] In RACH-less scenarios, when changing cells, the terminal device can avoid initiating a random access procedure in the candidate target cell. Considering that LTM is mainly designed for short interruption times, Rel-18 supports RACH-less procedures. If NR supports RACH-less conditional LTM in subsequent evolutions, it will lead to information discrepancies between the network and the UE. The network will not know when the UE will switch, forcing it to continuously reserve resources, resulting in resource waste. If resources are not continuously reserved, robustness issues will arise.

[0100] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be arbitrarily combined with each other.

[0101] Example 1

[0102] Example 1 illustrates a flowchart of LTM switching according to an embodiment of the present invention, as shown in Figure 1. In Figure 1, each box represents a step. It is particularly important to emphasize that the order of the boxes in the figure does not represent the temporal sequence of the steps represented.

[0103] In Embodiment 1, the first node in this invention can be a terminal device, such as a UE. The method for operating the first node is as follows:

[0104] Step S101: Receive RRC signaling sent by the source cell, wherein the RRC signaling includes configuration information of the first candidate target cell; the configuration information of the first candidate target cell includes a first execution condition;

[0105] Step S102: In response to the first execution condition being met, perform LTM cell handover;

[0106] Step S103, initiate the process of sending SR to the first candidate target cell, wherein the process of initiating the process of sending SR to the first candidate target cell depends on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover.

[0107] The meaning of sending an SR to the first candidate target cell depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the process of sending an SR to the first candidate target cell is initiated only when the LTM cell handover being performed is a RACH-free LTM cell handover.

[0108] As an example, the meaning of sending the SR only when the LTM cell handover being performed is an LTM cell handover without RACH is: before the LTM cell handover is completed, the process of sending the SR to the first candidate target cell is performed only when the LTM cell handover being performed is an LTM cell handover without RACH.

[0109] Specifically, in step S101, the first node receives RRC signaling from the source cell. The source cell can be the serving cell of the first node. The RRC signaling is an RRC message.

[0110] As an example, the RRC message is a downlink (DL) RRC message.

[0111] As an example, the RRC message is an RRC message for a sidelink (SL).

[0112] As an example, the RRC message is a UE-specific RRC message. A UE-specific RRC message refers to an RRC message transmitted through a Dedicated Control Channel (DCCH).

[0113] As an example, a UE-specific RRC message refers to an RRC message transmitted via SCCH (Dedicated Control Channel).

[0114] As an example, a UE-specific RRC message refers to an RRC message transmitted via Signalalling radio bearer 1 (SRB1) or Signalalling radio bearer 3 (SRB3).

[0115] As an example, a UE-specific RRC message refers to: an RRC message transmitted via SL-SRB3; or, a unicast RRC message.

[0116] As an example, the RRC message is any one of the following: RRCReconfiguration message, RRCResume message, RRCReestablishment message, and RRCReconfigurationSidelink message.

[0117] As an example, the RRC message is a DLInformationTransferMRDC message, which includes an RRCReconfiguration message.

[0118] As one example, the RRC message includes one or more RRC information blocks. In specific implementations, the RRC information block is an RRC container (contenter), or an RRC IE (Information Element), or an RRC message.

[0119] As an example, the RRC information block includes at least one RRC IE and / or at least one RRC field.

[0120] As one embodiment, the RRC information block includes configuration information for at least one candidate target cell. The configuration information for the at least one candidate target cell includes the configuration information for the first candidate target cell.

[0121] As a sub-implementation of this embodiment, the RRC information block includes configuration information for only one candidate target cell. In this case, the RRC information block includes the configuration information of the first candidate target cell.

[0122] Alternatively, the RRC information block may include configuration information for each candidate target cell in the cell group to which the first candidate target cell belongs.

[0123] As an example, the RRC information block includes configuration information of at least one candidate target cell, wherein the first candidate target cell is one of the at least one candidate target cells.

[0124] As an example, the configuration information of the first candidate target cell includes the physical layer configuration information of the first candidate target cell.

[0125] As an example, the configuration information of the first candidate target cell includes the C-RNTI of the first node in the first candidate target cell.

[0126] As an example, the configuration information of the first candidate target cell includes the public configuration information of the first candidate target cell.

[0127] As an example, the configuration information of the first candidate target cell includes at least some fields in the ServingCellConfigCommon IE.

[0128] As an example, the configuration information of the first candidate target cell includes the PCI of the first candidate target cell.

[0129] As an example, the configuration information of the first candidate target cell includes the downlink common configuration (DownlinkConfigCommon) and / or the uplink common configuration (UplinkConfigCommon) of the first candidate target cell.

[0130] As an example, the configuration information of the first candidate target cell includes the period of the SSB of the first candidate target cell.

[0131] As an example, the configuration information of the first candidate target cell includes the PBCH of the first candidate target cell.

[0132] As one embodiment, the RRC information block is a CellGroupConfig IE; or it includes a cellGroupId, which indicates the cell group to which the first candidate target cell belongs.

[0133] As an example, the RRC information block is associated with a first candidate configuration index, which indicates the first candidate target cell.

[0134] As one embodiment, the RRC message includes a first candidate configuration index, which indicates the first candidate target cell. The first candidate configuration index can be used to indicate the first candidate target cell, or it can be used to indicate the first candidate target cell in an LTM command, or it can be used to indicate the first candidate target cell in a PDCCH order.

[0135] In a specific implementation, the configuration information of the first candidate target cell may include a first execution condition. In one embodiment, the first execution condition refers to the execution condition that satisfies LTM cell handover.

[0136] For example, the first execution condition includes: the signal strength or channel quality of the source cell is lower than or equal to a preset first threshold.

[0137] For example, the first execution condition includes: the signal strength or channel quality of the source cell is lower than or equal to a preset first threshold, and the signal strength or channel quality of the candidate target cell is higher than or equal to a preset second threshold.

[0138] As an example, the RRC message may also include the preset first threshold, and the preset second threshold, for example, is carried by the RRC information block.

[0139] As a variation, the preset first threshold and the preset second threshold are either defaults or issued by other RRC messages.

[0140] As an example, the RRC information block is configured with an event indicating that the LTM has been executed.

[0141] As an example, the RRC information block includes a newUE-Identity field, which indicates the first node's C-RNTI in the first candidate target cell.

[0142] As an example, the RRC information block includes a ServingCellConfigCommon IE, which includes the PhysCellId of the first candidate target cell.

[0143] As an example, the RRC information block includes a CellGroupConfig IE, which includes the ServingCellConfigCommon IE.

[0144] In another embodiment, the RRC information block includes a SpCellConfig field, which includes the ServingCellConfigCommon IE. Alternatively, the RRC information block includes a ReconfigurationWithSync field, which includes the ServingCellConfigCommon IE.

[0145] As a sub-implementation of this embodiment, the ServingCellConfigCommon IE includes a DownlinkConfigCommon IE or an UplinkConfigCommon IE.

[0146] As a sub-implementation of this embodiment, the ServingCellConfigCommon IE includes an n-TimingAdvanceOffset field or an ssb-PositionsInBurst field.

[0147] As a sub-implementation of this embodiment, the ServingCellConfigCommon IE includes an ss-PBCH-BlockPower domain.

[0148] As an example, after the RRC signaling is received, the configuration information of each candidate target cell is stored. For example, the configuration information of the first candidate target cell is stored in a first variable.

[0149] In practice, the first variable can be VarConditionalReconfig.

[0150] As an example, the name of the first variable includes at least one of Var, LTM, Mobility, L1, or L2.

[0151] As a sub-implementation of this embodiment, in response to the receipt of the RRC message, the RRC information block is stored or updated in the first variable.

[0152] As a sub-implementation of this embodiment, in response to the receipt of the RRC message, the configuration information of the candidate target cell is stored or updated in the first variable.

[0153] As a sub-implementation of this embodiment, in response to the receipt of the RRC message, the configuration information of each candidate target cell in the RRC information block is stored or updated in the first variable.

[0154] As an example, the first variable can be used in LTM. For example, for RACH-based LTM, or for LTM without RACH.

[0155] In step S102, when the first node meets the first execution condition, LTM cell handover can be performed.

[0156] As an example, whether the LTM cell handover is RACH-based LTM or RACH-free LTM depends on the RRC signaling.

[0157] In specific implementation, the RRC signaling includes executing RACH-based LTM configuration information. The first node can trigger a random access procedure on the first candidate target cell based on the configuration information. The random access procedure is a CFRA. Alternatively, the random access procedure is a CBRA.

[0158] As a variation of the implementation, the first execution condition includes the condition of performing LTM without RACH, wherein the LTM handover is an LTM cell handover without RACH.

[0159] In step S103, depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover, the first node may send an SR to the first candidate target cell.

[0160] In practice, the first node sends the SR only when the LTM cell handover being performed is an LTM cell handover without RACH.

[0161] In practice, the purpose of sending the SR is not to request uplink resources.

[0162] In practice, the first candidate target cell that receives the SR can be considered as the first node that issued the SR having successfully completed LTM cell handover.

[0163] In practice, the purpose of sending the SR is to complete the LTM handover.

[0164] For example, the purpose of sending the SR is to complete LTM without RACH.

[0165] For example, the purpose of sending the SR is to inform the first candidate target cell that the first node is performing LTM without RACH.

[0166] As an example, the transmission of the SR is independent of whether there is data to be transmitted.

[0167] As an example, the transmission of the SR is independent of whether there is a MAC CE to be transmitted.

[0168] As an example, whether or not the SR is sent is independent of the data to be transmitted and the MAC CE.

[0169] As an example, the transmission of the SR does not depend on whether there is data to be transmitted.

[0170] As an example, the transmission of the SR does not depend on whether there is a pending MAC CE.

[0171] As an example, the transmission of the SR does not depend on whether there is data to be transmitted, nor on whether there is a MAC CE to be transmitted.

[0172] As an example, the SR is not associated with any data.

[0173] As an example, the SR is not associated with any MAC CE.

[0174] As an example, the first node does not require listening to the PDCCH of the first candidate target cell before the SR is sent.

[0175] As an example, in response to receiving the PDCCH scheduling of the first candidate target cell, the process of sending the SR to the first candidate target cell is cancelled.

[0176] As an example, in response to receiving a PDCCH schedule from any candidate target cell, the process of sending an SR to the first candidate target cell is cancelled.

[0177] As an example, the SR is the first SR sent to the first candidate target cell.

[0178] As an example, the SR is the first signal sent to the first candidate target cell.

[0179] In specific implementation, the first node can determine when to send the SR to the first candidate target cell based on the physical layer synchronization of the first candidate target cell. The first node triggers the SR after completing the physical layer downlink synchronization and uplink synchronization with the first candidate target cell, and sends the SR to the first candidate target cell.

[0180] As an example, the configuration information of the first candidate target cell is used to trigger the SR.

[0181] As an example, at least the configuration information in the configuration information of the first candidate target cell is used to trigger the SR.

[0182] As an example, the first node determines in step S102 to perform LTM without RACH before executing step S103 to trigger the SR.

[0183] As an example, the sending of the SR to the first candidate target cell is performed after the LTM cell handover begins.

[0184] As an example, the sending of the SR to the first candidate target cell is performed before the LTM cell handover is completed.

[0185] As an example, the sending of the SR to the first candidate target cell is performed during the LTM cell handover. In this case, steps S102 and S103 are executed in parallel.

[0186] As an example, based on the configuration information of the first candidate target cell, the RRC sublayer of the first node sends an indication to the lower layer of the first node; for example, it sends an indication to the MAC sublayer of the first node, and the MAC sublayer responds to the indication by triggering the SR.

[0187] As an example, no uplink data was used to trigger the SR.

[0188] As a sub-implementation of this embodiment, the SR is triggered when there is no uplink data.

[0189] As a sub-example of this embodiment, when the SR is triggered, there is no uplink data.

[0190] As an example, the SR is triggered regardless of whether there is uplink data.

[0191] As a sub-example of this embodiment, when the SR is triggered, there is no uplink data.

[0192] As a sub-implementation of this embodiment, when the SR is triggered, there is uplink data.

[0193] As one example, the uplink data includes PDUs or SDUs cached in a PDCP entity or an RLC entity.

[0194] As an example, the first node can autonomously obtain the timing of the candidate target cell and complete the uplink synchronization in advance.

[0195] In practice, during the uplink synchronization process for the first candidate target cell, if the RRC message indicates that the first node should measure the timing advance itself, then the first node can measure the timing advance of the source cell and determine the timing advance of the first candidate target cell based on the reception time difference between the source cell and the first candidate target cell.

[0196] As an example, the first node can start a timer when the SR is triggered; when the timer expires, the process of sending the SR to the first candidate target cell is canceled, and the execution of RACH-based LTM is rolled back.

[0197] As an example, the fallback execution of RACH-based LTM only includes contention-based random access CBRA LTM.

[0198] As a variation, the rollback execution of RACH-based LTM includes CBRA-based LTM and CFRA-based LTM. The advantage lies in its higher flexibility and reduced handover latency.

[0199] As another variation, the first node can update the counter when the SR transmission fails; when the counter reaches a preset value, the counter is reset, and the process of sending the SR to the first candidate target cell is canceled, and the RACH-based LTM is rolled back; wherein, the counter is used to record the number of SR transmission failures.

[0200] In practice, if the counter used to record the number of failed SR transmissions is initially set to 0, the counter can be incremented by 1 when the SR transmission fails. When the counter reaches a preset value, such as the maximum value, the counter can be reset, and SR transmission to the first candidate target cell can be stopped. Furthermore, this LTM cell handover will no longer execute LTM without RACH, but will fall back to executing LTM based on RACH.

[0201] In a modified implementation, the initial value of the counter used to record the number of failed SR transmissions is a preset value (e.g., a non-zero maximum value). When the first node fails to transmit the SR, the counter can be decremented by 1. When the counter reaches 0, the counter can be reset to the preset value, and SR transmission to the first candidate target cell can be stopped. Furthermore, this LTM cell handover will no longer execute LTM without RACH, but will fall back to executing LTM based on RACH.

[0202] As one embodiment, the first node can cancel the timer after successfully sending the SR to the first candidate target cell during the timer's operation. Here, the SR is the first uplink signal sent by the first node to the first candidate target cell. As a variation, the first node can stop the timer after successfully sending the SR to the first candidate target cell during the timer's operation.

[0203] As one embodiment, the configuration information of the first candidate target cell may include one or more candidate SR configurations, each of which is associated with at least one SR resource. The first cell may send an SR to the first candidate target cell on one of the at least one SR resources.

[0204] As an example, the candidate SR configuration can be used for the SR.

[0205] As an example, the SR can be configured using the candidate SR.

[0206] As an example, any valid Physical Uplink Control Channel (PUCCH) resource in the candidate SR configuration is used in the SR.

[0207] As an example, any valid SR resource in the candidate SR configuration is used for the SR.

[0208] As an example, the candidate SR configuration includes no more than maxNrofSR-ConfigPerCellGroup of candidate SR configurations.

[0209] As an example, the candidate SR configuration is configured for the first node.

[0210] As an example, the candidate SR configurations are configured in the same MAC entity.

[0211] As an example, the candidate SR configuration is configured in the first candidate target cell.

[0212] As an example, the candidate SR configuration is configured for the first candidate target cell.

[0213] As an example, the candidate SR configuration is configured to the cell group to which the first candidate target cell belongs.

[0214] As an example, the candidate SR configuration is configured to the MAC entity to which the cell group to which the first candidate target cell belongs.

[0215] As an example, the candidate SR configuration is configured to a BWP (bandwidth part) of the first candidate target cell.

[0216] As an example, the candidate SR configuration is indexed by a SchedulingRequestId.

[0217] As an example, the candidate SR configuration is associated with a PUCCH resource.

[0218] As an example, the candidate SR configuration is indicated by an index of at least one PUCCH resource.

[0219] As an example, the candidate SR configuration includes an index of a PUCCH resource.

[0220] As an example, the candidate SR configuration includes PUCCH resources.

[0221] As an example, the SR resource is a physical layer resource, a PUCCH resource, and / or a PUCCH resource used for SR.

[0222] As an example, the SR resource refers to the PUCCH resource indexed by the ScheduledRequestResourceId.

[0223] As an example, when the L1 / L2 signaling is received, the first cell is a PCell, and the first candidate target cell is a secondary cell in the cell group to which the first cell belongs.

[0224] As an example, the source cell is a PSCell, and the first candidate target cell is a secondary cell in the cell group to which the source cell belongs.

[0225] As an example, the source cell is a PCell, and the first candidate target cell is an SCell.

[0226] As an example, the source cell is a PSCell, and the first candidate target cell is an SCell.

[0227] As an example, the source cell is a PCcell, and the first candidate target cell is a PSCell.

[0228] As an example, the source cell is a PCell, and the first candidate target cell is a secondary cell in an MCG.

[0229] As an example, the source cell is a PSCell, and the first candidate target cell is a secondary cell in an SCG.

[0230] After successfully receiving the SR, the first candidate target cell becomes the new serving cell of the first node. The first candidate target cell can send a signaling message to the first node, which may include deleting the context information of the source cell. Upon receiving the signaling message, the first node can delete the context information of the source cell. In specific implementations, the signaling message can be higher-level signaling or non-higher-level signaling, such as an RRC reconfiguration message or a MAC CE.

[0231] As an example, sending an SR in this application refers to sending a signal indicating an SR.

[0232] As a sub-example of this embodiment, the signal indicating the SR is a physical layer signal.

[0233] As a sub-example of this embodiment, the signal indicating SR is a signal on PUCCH.

[0234] As an example, sending an SR signal in this application refers to sending a signal indicating an SR.

[0235] As a sub-example of this embodiment, the signal indicating the SR is a physical layer signal.

[0236] As a sub-example of this embodiment, the signal indicating SR is a signal on PUCCH.

[0237] Example 2

[0238] Example 2 illustrates a network architecture diagram according to an embodiment of the present invention, as shown in Figure 2. Figure 2 illustrates a network architecture 200 of an NR 5G, LTE, and LTE-A (Long-Term Evolution Advanced) system. The NR 5G, LTE, or LTE-A network architecture 200 may be referred to as 5GS (5G System) / EPS (Evolved Packet System) 200 or some other suitable term. 5GS / EPS 200 may include one or more UEs 201, NG-RAN (Next Generation Radio Access Network) 202, 5GC (5G Core Network) / EPC (Evolved Packet Core) 210, HSS (Home Subscriber Server) / UDM (Unified Data Management) 220, and Internet services 230. 5GS / EPS may interconnect with other access networks, but these entities / interfaces are not shown for simplicity. As shown in the figure, 5GS / EPS provides packet-switched services; however, those skilled in the art will readily understand that the various concepts presented throughout this invention can be extended to networks or other cellular networks that provide circuit-switched services. NG-RAN includes NR Node B (gNB) 203 and other gNBs 204. gNB 203 provides user and control plane protocol termination to UE 201. gNB 203 can connect to other gNBs 204 via an Xn interface (e.g., backhaul). gNB 203 may also be referred to as a base station, base transceiver station, radio base station, radio transceiver, transceiver function, Basic Service Set (BSS), Extended Service Set (ESS), TRP (Transmission Reception Point), or some other suitable term. In NTN (Non-Terrestrial Network) networks, gNB 203 can be a satellite, an aircraft, or a terrestrial base station relayed via satellite. gNB 203 provides UE 201 with access to 5GC / EPC 210.Examples of UE201 include cellular phones, smartphones, Session Initiation Protocol (SIP) phones, laptops, personal digital assistants (PDAs), satellite radios, global positioning systems, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, drones, aircraft, narrowband IoT devices, machine-type communication devices, land vehicles, automobiles, in-vehicle equipment, in-vehicle communication units, wearable devices, or any other similar functional devices. Those skilled in the art may also refer to UE201 as a mobile station, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handheld device, user agent, mobile client, client, or any other suitable term. The gNB203 connects to the 5GC / EPC210 via the S1 / NG interface. The 5GC / EPC210 includes the MME (Mobility Management Entity) / AMF (Authentication Management Field) / SMF (Session Management Function) 211, other MMEs / AMFs / SMFs 214, the S-GW (Service Gateway) / UPF (User Plane Function) 212, and the P-GW (Packet Data Network Gateway) / UPF 213. The MME / AMF / SMF 211 is the control node that handles signaling between the UE201 and the 5GC / EPC210. ​​Generally, the MME / AMF / SMF 211 provides bearer and connection management. All user IP (Internet Protocol) packets are transmitted through the S-GW / UPF 212, which is itself connected to the P-GW / UPF 213. The P-GW provides UE IP address allocation and other functions. The P-GW / UPF213 connects to Internet service 230. Internet service 230 includes carrier-compliant Internet protocol services, specifically including Internet, intranet, IMS (IP Multimedia Subsystem), and PS (Packet Switching) streaming services.

[0239] As an example, UE201 corresponds to the first node in this invention.

[0240] As an example, gNB203 corresponds to the second node and / or the third node in this invention.

[0241] As an example, the gNB203 is a macrocell base station.

[0242] As an example, the gNB203 is a microcell base station.

[0243] As an example, the gNB203 is a pico cell base station.

[0244] As an example, the gNB203 is a femtocell.

[0245] As an example, the gNB203 is a base station device that supports large latency differences.

[0246] As one example, the gNB203 is a flight platform device.

[0247] As an example, the gNB203 is a satellite device.

[0248] As one embodiment, the gNB203 is a test device (e.g., a transceiver device simulating part of the functions of a base station, a signaling tester).

[0249] As an example, the other gNB204 is a macrocell base station.

[0250] As an example, the other gNB204 is a microcell base station.

[0251] As an example, the other gNB204 is a pico cell base station.

[0252] As an example, the other gNB204 is a femtocell.

[0253] As an example, the other gNB204 is a base station device that supports large latency differences.

[0254] As an example, the other gNB204 is a flight platform device.

[0255] As an example, the other gNB204 is a satellite device.

[0256] As one embodiment, the other gNB204 is a test device (e.g., a transceiver device simulating part of the base station's functions, a signaling tester).

[0257] As an example, the radio link from the UE201 to the gNB203 is an uplink, which is used to perform uplink transmissions.

[0258] As an example, the radio link from the gNB203 to the UE201 is a downlink, which is used to perform downlink transmissions.

[0259] As an example, the UE201 and the gNB203 are connected via a Uu interface.

[0260] Example 3

[0261] Example 3 illustrates a schematic diagram of an embodiment of a wireless protocol architecture for a user plane and control plane according to the present invention, as shown in Figure 3. Figure 3 is a schematic diagram illustrating an embodiment of a radio protocol architecture for a user plane 350 and a control plane 300. Figure 3 shows the radio protocol architecture for the control plane 300 using three layers: L1, L2, and L3. The L1 layer is the lowest layer and implements various PHY (Physical Layer) signal processing functions. The L1 layer will be referred to herein as PHY 301. The L2 layer 305 is above PHY 301 and includes a MAC (Medium Access Control) sublayer 302, an RLC (Radio Link Control) sublayer 303, and a PDCP (Packet Data Convergence Protocol) sublayer 304. The PDCP sublayer 304 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 304 also provides security through encrypted data packets and provides cross-area mobility support. RLC sublayer 303 provides upper-layer packet segmentation and reassembly, retransmission of lost packets, and packet reordering to compensate for out-of-order reception caused by HARQ (Hybrid Automatic Repeat Request). MAC sublayer 302 provides multiplexing between the logical and transport channels. MAC sublayer 302 is also responsible for allocating various radio resources (e.g., resource blocks) within a cell. MAC sublayer 302 is also responsible for HARQ operations. RRC (Radio Resource Control) sublayer 306 in the L3 layer of the control plane 300 is responsible for acquiring radio resources (i.e., radio bearers) and using RRC signaling to configure the lower layers. The radio protocol architecture of user plane 350 includes L1 and L2 layers. In user plane 350, the radio protocol architecture for physical layer 351, PDCP sublayer 354 in L2 layer 355, RLC sublayer 353 in L2 layer 355, and MAC sublayer 352 in L2 layer 355 is largely the same as the corresponding layers and sublayers in control plane 300. However, PDCP sublayer 354 also provides header compression for upper layer packets to reduce radio transmission overhead. L2 layer 355 in user plane 350 also includes SDAP (Service Data Adaptation Protocol) sublayer 356. SDAP sublayer 356 is responsible for mapping between QoS streams and data radio bearers (DRBs) to support service diversity.

[0262] As an example, the wireless protocol architecture in Figure 3 is applicable to the first node in this invention.

[0263] As an example, the wireless protocol architecture in Figure 3 is applicable to the second node in this invention.

[0264] As an example, the wireless protocol architecture in Figure 3 is applicable to the third node described in this invention.

[0265] As an example, the RRC message in this invention is generated in RRC306.

[0266] As an example, the LTM signaling in this invention is generated in MAC302 or MAC352.

[0267] As an example, the LTM signaling in this invention is generated in the PHY301 or PHY351.

[0268] As an example, the process of sending SR to the first candidate target cell in this invention is generated by MAC302 or MAC352.

[0269] As an example, the process of sending SR to the first candidate target cell in this invention is canceled by MAC302 or MAC352.

[0270] As an example, the SR signal in this invention is generated in the PHY301 or PHY351.

[0271] Example 4

[0272] Example 4 illustrates a hardware module schematic diagram of a communication device according to an embodiment of the present invention, as shown in Figure 4. Figure 4 is a block diagram of a first communication device 450 and a second communication device 410 communicating with each other in an access network.

[0273] The first communication device 450 includes a controller / processor 459, a memory 460, a data source 467, a transmitting processor 468, a receiving processor 456, a multi-antenna transmitting processor 457, a multi-antenna receiving processor 458, a transmitter / receiver 454, and an antenna 452.

[0274] The second communication device 410 includes a controller / processor 475, a memory 476, a data source 477, a receiver processor 470, a transmitter processor 416, a multi-antenna receiver processor 472, a multi-antenna transmitter processor 471, a transmitter / receiver 418, and an antenna 420.

[0275] In the transmission from the second communication device 410 to the first communication device 450, at the second communication device 410, upper-layer data packets from the core network or from the data source 477 are provided to the controller / processor 475. The core network and data source 477 represent all protocol layers above the L2 layer. The controller / processor 475 implements the functionality of the L2 layer. In the transmission from the second communication device 410 to the first communication device 450, the controller / processor 475 provides header compression, encryption, packet segmentation and reordering, multiplexing between logical and transport channels, and radio resource allocation for the first communication device 450 based on various priority metrics. The controller / processor 475 is also responsible for retransmitting lost packets and signaling to the first communication device 450. The transmit processor 416 and the multi-antenna transmit processor 471 implement various signal processing functions for the L1 layer (i.e., the physical layer). Transmit processor 416 performs encoding and interleaving to facilitate forward error correction (FEC) at the second communication device 410, and mapping of signal clusters based on various modulation schemes (e.g., Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), M-Phase Shift Keying (M-PSK), M-QAM). Multi-antenna transmit processor 471 performs digital spatial precoding on the encoded and modulated symbols, including codebook-based and non-codebook-based precoding, and beamforming processing, generating one or more spatial streams. Transmit processor 416 then maps each spatial stream to subcarriers, multiplexes it with a reference signal (e.g., a pilot) in the time and / or frequency domains, and subsequently uses inverse fast Fourier transform (IFFT) to generate a physical channel carrying the time-domain multicarrier symbol stream. Multi-antenna transmit processor 471 then performs transmit analog precoding / beamforming operations on the time-domain multicarrier symbol stream. Each transmitter 418 converts the baseband multicarrier symbol stream provided by the multi-antenna transmitter processor 471 into an radio frequency stream, which is then provided to different antennas 420.

[0276] In the transmission from the second communication device 410 to the first communication device 450, at the first communication device 450, each receiver 454 receives a signal through its corresponding antenna 452. Each receiver 454 recovers the information modulated onto the radio frequency carrier and converts the radio frequency stream into a baseband multicarrier symbol stream, which is then provided to the receiver processor 456. The receiver processor 456 and the multi-antenna receiver processor 458 implement various signal processing functions of the L1 layer. The multi-antenna receiver processor 458 performs receive analog precoding / beamforming operations on the baseband multicarrier symbol stream from the receiver 454. The receiver processor 456 uses a Fast Fourier Transform (FFT) to convert the baseband multicarrier symbol stream after the receive analog precoding / beamforming operations from the time domain to the frequency domain. In the frequency domain, the physical layer data signal and the reference signal are demultiplexed by the receiver processor 456, where the reference signal is used for channel estimation, and the data signal is recovered in the multi-antenna receiver processor 458 after multi-antenna detection to recover any spatial stream destined for the first communication device 450. Symbols on each spatial stream are demodulated and recovered in the receive processor 456, generating soft decisions. The receive processor 456 then decodes and deinterleaves the soft decisions to recover the upper-layer data and control signals transmitted by the second communication device 410 over the physical channel. The upper-layer data and control signals are then provided to the controller / processor 459. The controller / processor 459 implements the functions of Layer 2. The controller / processor 459 may be associated with a memory 460 storing program code and data. The memory 460 may be referred to as computer-readable media. In the transmission from the second communication device 410 to the first communication device 450, the controller / processor 459 provides multiplexing, packet reassembly, decryption, header decompression, and control signal processing between the transmission and logical channels to recover the upper-layer data packets from the second communication device 410. The upper-layer data packets are then provided to all protocol layers above Layer 2. Various control signals may also be provided to Layer 3 for Layer 3 processing.

[0277] In the transmission from the first communication device 450 to the second communication device 410, at the first communication device 450, upper-layer data packets are provided to the controller / processor 459 using a data source 467. The data source 467 represents all protocol layers above the L2 layer. Similar to the transmission functions at the second communication device 410 described in the transmission from the second communication device 410 to the first communication device 450, the controller / processor 459 implements header compression, encryption, packet segmentation and reordering, and multiplexing between the logical and transport channels, implementing L2 layer functions for the user plane and control plane. The controller / processor 459 is also responsible for retransmitting lost packets and signaling to the second communication device 410. Transmit processor 468 performs modulation mapping and channel coding processing, while multi-antenna transmit processor 457 performs digital multi-antenna spatial precoding, including codebook-based and non-codebook-based precoding, and beamforming processing. Subsequently, transmit processor 468 modulates the generated spatial stream into a multi-carrier / single-carrier symbol stream. After analog precoding / beamforming operations in multi-antenna transmit processor 457, the stream is provided to different antennas 452 via transmitter 454. Each transmitter 454 first converts the baseband symbol stream provided by multi-antenna transmit processor 457 into a radio frequency symbol stream before providing it to antenna 452.

[0278] In the transmission from the first communication device 450 to the second communication device 410, the function at the second communication device 410 is similar to the receiving function at the first communication device 450 described in the transmission from the second communication device 410 to the first communication device 450. Each receiver 418 receives radio frequency signals through its corresponding antenna 420, converts the received radio frequency signals into baseband signals, and provides the baseband signals to the multi-antenna receiving processor 472 and the receiving processor 470. The receiving processor 470 and the multi-antenna receiving processor 472 jointly implement the L1 layer function. The controller / processor 475 implements the L2 layer function. The controller / processor 475 may be associated with a memory 476 storing program code and data. The memory 476 may be referred to as computer-readable media. In the transmission from the first communication device 450 to the second communication device 410, the controller / processor 475 provides multiplexing between the transmission and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover the upper-layer data packets from the first communication device 450. Upper-layer data packets from the controller / processor 475 can be provided to the core network or all protocol layers above the L2 layer, and various control signals can also be provided to the core network or L3 for L3 processing.

[0279] As one embodiment, the first communication device 450 includes: at least one processor and at least one memory, the at least one memory including computer program code; the at least one memory and the computer program code are configured to be used with the at least one processor, and the first communication device 450 includes at least: receiving RRC signaling sent by a source cell, the RRC signaling including configuration information of at least a first candidate target cell; the configuration information of the first candidate target cell including a first execution condition; performing an LTM cell handover as a response to the first execution condition being met; and initiating a process of sending an SR to the first candidate target cell, wherein the process of initiating a process of sending an SR to the first candidate target cell depends on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover; wherein, the meaning of the process of initiating a process of sending an SR to the first candidate target cell depending on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the process of initiating a process of sending an SR to the first candidate target cell is executed only when the LTM cell handover performed is a RACH-free LTM cell handover.

[0280] As one embodiment, the first communication device 450 includes: a memory storing a computer-readable instruction program, which generates actions when executed by at least one processor, the actions including: receiving RRC signaling sent by a source cell, the RRC signaling including configuration information of a first candidate target cell; the configuration information of the first candidate target cell including a first execution condition; performing an LTM cell handover as a response to the first execution condition being met; sending an SR to the first candidate target cell, wherein sending the SR to the first candidate target cell depends on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover; wherein, the meaning of sending the SR to the first candidate target cell depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the SR is sent only when the LTM cell handover being performed is a RACH-free LTM cell handover.

[0281] As one embodiment, the second communication device 410 includes: at least one processor and at least one memory, the at least one memory including computer program code; the at least one memory and the computer program code are configured to be used with the at least one processor. The second communication device 410 at least: receives a signal SR, the SR depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover; the meaning of the SR depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the SR is sent only if the LTM cell handover being performed is a RACH-free LTM cell handover; wherein the SR is triggered by the satisfaction of a first execution condition, the first execution condition being included in the configuration information of a first candidate target cell, the configuration information of the first candidate target cell being included in the RRC signaling from the source cell to the sender of the SR.

[0282] As one embodiment, the second communication device 410 includes: a memory storing a computer-readable instruction program that generates actions when executed by at least one processor, the actions including: receiving a signal relay (SR), the SR depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover; the meaning of the SR depending on whether the LTM cell handover being performed is a RACH-free LTM cell handover or a RACH-free LTM cell handover is: the SR is sent only if the LTM cell handover being performed is a RACH-free LTM cell handover; wherein the SR is triggered by the satisfaction of a first execution condition, the first execution condition being included in the configuration information of a first candidate target cell, the configuration information of the first candidate target cell being included in the RRC signaling from the source cell to the sender of the SR.

[0283] As one embodiment, the second communication device 410 includes: at least one processor and at least one memory, the at least one memory including computer program code; the at least one memory and the computer program code are configured to be used with the at least one processor. The second communication device 410 at least: sends RRC signaling to a first node, the RRC signaling including configuration information of at least a first candidate target cell; the configuration information of the first candidate target cell includes a first execution condition; wherein, when the first execution condition is met, the first node performs an LTM cell handover; sends an SR to the first candidate target cell, the sending of the SR to the first candidate target cell depending on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover; the meaning of sending the SR to the first candidate target cell depending on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the SR is sent only when the performed LTM cell handover is a RACH-free LTM cell handover.

[0284] As one embodiment, the second communication device 410 includes: a memory storing a computer-readable instruction program that generates actions when executed by at least one processor, the actions including: sending RRC signaling to a first node, the RRC signaling including configuration information of at least a first candidate target cell; the configuration information of the first candidate target cell including a first execution condition; wherein, when the first execution condition is met, the first node performs an LTM cell handover; sending an SR to the first candidate target cell, wherein sending the SR to the first candidate target cell depends on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover; the meaning of sending the SR to the first candidate target cell depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the SR is sent only when the LTM cell handover being performed is a RACH-free LTM cell handover.

[0285] As an example, the first communication device 450 corresponds to the first node in this invention.

[0286] As an example, the second communication device 410 corresponds to the second node in this invention.

[0287] As an example, the second communication device 410 corresponds to the third node in this invention.

[0288] As an example, the first communication device 450 is a UE.

[0289] As an example, the first communication device 450 is a relay.

[0290] As one embodiment, the second communication device 410 is a base station device.

[0291] As one embodiment, the second communication device 410 is a base station distribution unit.

[0292] As one embodiment, the second communication device 410 is a piece of code in the distribution unit of a base station.

[0293] As an example, at least one of the antenna 452, the transmitter 454, the multi-antenna transmitter processor 457, the transmitter processor 468, or the controller / processor 459 is used to transmit the uplink signal in this invention.

[0294] As an example, at least one of the antenna 420, the receiver 418, the multi-antenna receiver processor 472, the receiver processor 470, or the controller / processor 475 is used to receive the uplink signal in this invention.

[0295] As an example, at least one of the antenna 420, the transmitter 418, the multi-antenna transmitter processor 471, the transmitter processor 416, or the controller / processor 475 is used to transmit the first information in this invention.

[0296] As an example, at least one of the antenna 452, the receiver 454, the multi-antenna receiving processor 458, the receiving processor 456, or the controller / processor 459 is used to receive the first information in this invention.

[0297] As an example, at least one of the antenna 420, the transmitter 418, the multi-antenna transmitter processor 471, the transmitter processor 416, or the controller / processor 475 is used to transmit RRC signaling in this invention.

[0298] As one embodiment, at least one of the antenna 452, the receiver 454, the multi-antenna receiving processor 458, the receiving processor 456, or the controller / processor 459 is used to receive RRC signaling in this invention.

[0299] As an example, at least one of the antenna 420, the transmitter 418, the multi-antenna transmitter processor 471, the transmitter processor 416, or the controller / processor 475 is used to transmit the SR signal in this invention.

[0300] Example 5

[0301] Example 5 illustrates a wireless signal transmission flowchart according to an embodiment of the present invention, as shown in Figure 5. It should be noted that the order in this example does not limit the signal transmission order or the order of implementation in the present invention.

[0302] For the first node N51, in step S511, RRC signaling is received, which is an RRC message. The RRC signaling is sent by the source cell, i.e., the third node N53. In one embodiment, the third node N53 is also the base station of the serving cell.

[0303] The first node N51 performs LTM cell handover in step S512. In step S513, an SR is triggered, in step S514, a timer is started, and in step S515, an SR is sent. In step S516, the timer is canceled.

[0304] For the second node N52, SR is received in step S521 and LTM cell handover is completed in step S522.

[0305] For the third node N53, an RRC signaling is sent in step S531. The RRC signaling is sent to the first node N51.

[0306] Specifically, after receiving the RRC signaling, the first node N51 can store the RRC signaling. The RRC signaling includes configuration information of a first candidate target cell; the configuration information of the first candidate target cell includes a first execution condition. After receiving the RRC signaling, the first node N51 can determine whether a RACH-based LTM cell handover can be performed, and whether a RACH-free LTM handover can be performed. When performing an LTM cell handover, it can determine which candidate target cells can be used for the handover and the configuration information of each candidate target cell. In addition, the first node N51 can also learn the corresponding execution conditions for performing an LTM cell handover from the configuration information of each candidate target cell.

[0307] Upon receiving the RRC signaling, the first node N51 can continue monitoring the source cell, for example, by measuring the reference signal of the source cell. The reference signal includes, but is not limited to, CSI-RS and SSB. Furthermore, the first node N51 can measure each candidate target cell based on the configuration information obtained from the RRC signaling, for example, by measuring the CSI-RS and / or SSB of each candidate target cell, thereby determining whether the first node N51 meets the first execution condition.

[0308] In one embodiment, the first execution condition includes satisfying the condition for LTM cell handover. Specifically, the first execution condition may include: the signal strength or channel quality of the source cell is lower than or equal to a preset first threshold. Alternatively, the first execution condition may include: the signal strength or channel quality of the source cell is lower than or equal to a preset first threshold, and the signal strength or channel quality of the candidate target cell is higher than or equal to a preset second threshold.

[0309] When the first node N51 satisfies the first execution condition, in response to the satisfaction of the first execution condition, the first node N51 may execute step S512 to perform LTM cell handover.

[0310] For example, the first node N51 can learn about the first execution condition in the configuration information of the first candidate target cell. Based on this, if the first node N51 determines through measurement that it meets the first execution condition, it can perform an LTM cell handover to the first candidate target cell.

[0311] As an example, LTM cell handover can be RACH-based LTM or RACH-free LTM.

[0312] In specific implementation, the first node N51 determines to perform RACH-based LTM to the first candidate target cell. At this time, a random access sequence can be sent to the first candidate target cell. It should be noted that the prerequisite for using RACH-based LTM is that the RRC signaling includes the random access resources configured on the first candidate target cell.

[0313] As a variation of the implementation, the first node N51 determines to perform RACH-free LTM to the first candidate target cell. In this case, an SR (Resource Request) can be sent to the first candidate target cell. It should be noted that the prerequisite for using RACH-free LTM is that the RRC signaling includes the SR resources configured on the first candidate target cell.

[0314] As an example, step S513. Triggering the SR includes initiating the process of sending an SR to the first candidate target cell.

[0315] As an example, the sending of the SR to the first candidate target cell is performed after the LTM cell handover begins.

[0316] As an example, the sending of the SR to the first candidate target cell is performed before the LTM cell handover is completed.

[0317] As an example, the first node is not required to listen to the PDCCH of the first candidate target cell before the SR is sent.

[0318] As an example, the first node is required to listen to the PDCCH of the first candidate target cell after the SR is sent.

[0319] As an example, in response to receiving the PDCCH scheduling of the first candidate target cell, the process of sending the SR to the first candidate target cell is cancelled.

[0320] In Figure 5, the first node N51 determines in step S512 to execute LTM without RACH. Under this condition, step S513 can be executed to trigger SR. Accordingly, the first node N51 can select a first candidate SR configuration for the SR, which is associated with at least one SR resource.

[0321] As an example, when the first node N51 performs LTM without RACH or before performing LTM without RACH, it needs to complete uplink synchronization with the first candidate target cell.

[0322] As an example, sending an SR to the first candidate target cell depends on synchronization with the first candidate target cell, meaning that the first node N51 needs to obtain a timing advance for the first candidate target cell before it can send the SR.

[0323] As an example, the first node N51 has obtained the timing advance for the first candidate target cell before initiating the process of sending SR to the first candidate target cell.

[0324] As an example, how to obtain the timing advance for the first candidate target cell is a prior art in the field.

[0325] In practice, after uplink synchronization, the first node N51 receives a PDCCH schedule from one of the candidate target cells. In response to receiving a PDCCH schedule from any candidate target cell, it cancels triggering the SR (Signal Sending) to the first candidate target cell and cancels sending the SR.

[0326] As an example, the meaning of canceling the process of sending SR to the first candidate target cell upon the expiration of the timer is: the expiration of the timer triggers the cancellation of the process of sending SR to the first candidate target cell.

[0327] As an example, once the SR is sent, the process of sending the SR to the first candidate target cell is completed.

[0328] When executing step S513, step S514 can be executed simultaneously to start a timer. The timer is used to record whether the triggered SR is sent before the timer expires. If the timer expires, the first node N51 executes step S515 to send the SR. At this time, step S516 can be executed to cancel or stop the timer.

[0329] As an example, the SR is sent at the physical layer.

[0330] As a sub-implementation of this embodiment, the SR is considered a high-priority SR transmission.

[0331] As a sub-example of this embodiment, the MAC entity considers the SR to be a SR that is prioritized for transmission.

[0332] As an example, the SR is a physical layer signal.

[0333] As an example, the SR is transmitted on the PUCCH.

[0334] As an example, the first candidate SR is configured with a valid PUCCH resource. The SR is transmitted on a valid PUCCH resource. The valid PUCCH resource is one valid PUCCH resource for the SR.

[0335] Then, node N52 executes step S521 to receive the SR and executes step S522 to complete the LTM cell handover.

[0336] In one variation, receiving the SR signifies the completion of the LTM cell handover. In another variation, the LTM cell handover is completed first, followed by receiving and processing the SR.

[0337] As an example, the present invention does not limit the order of steps S513 and S514.

[0338] As an example, step S516 is performed before step S515, or step S516 and step S515 are performed in parallel.

[0339] As an example, step S514 is subordinate to step S513 and is executed in parallel.

[0340] As an example, the first node N51 is a user equipment.

[0341] As an example, the first node N51 is a relay device.

[0342] As an example, the second node N52 is the sustaining node of the first candidate target cell.

[0343] As an example, the second node N52 is one of the TRP, DU, CU, and base station devices.

[0344] As an example, the third node N53 is the maintenance node of the source cell or serving cell.

[0345] As an example, the third node N53 is a TRP, DU, CU, radio frequency unit, or base station device.

[0346] As one embodiment, the backhaul between the second node N52 and the third node N53 may be ideal or non-ideal.

[0347] As one example, the second node N52 and the third node N53 belong to different CUs, different DUs, or different TRPs.

[0348] The specific descriptions of the various wireless signals in this embodiment can also refer to the relevant descriptions in Embodiment 1.

[0349] Example 6

[0350] Example 6 illustrates a wireless signal transmission flowchart according to another embodiment of the present invention, as shown in Figure 6. It should be noted that the order in this example does not limit the signal transmission order or the order of implementation in the present invention.

[0351] Figure 6 is a schematic diagram of a feasible process after the first node N51 starts the timer in step S514.

[0352] Specifically, after the timer starts, the first node N51 executes step S601 to determine if the timer has expired. If not, it executes step S602A to determine if the SR was successfully sent. If yes, it means the SR was successfully sent, and it proceeds to step S516 in embodiment 5. If no, it means the SR failed to be sent or was not successfully sent, and it proceeds to step S601 to continue monitoring the timer.

[0353] In specific implementation, if the timer expires, the process proceeds to step S602B after step S601, that is, the process of sending SR to the first candidate target cell is canceled, and the RACH-based LTM is rolled back.

[0354] As an example, the rollback execution of RACH-based LTM only includes CBRA-based LTM.

[0355] As an example, the rollback execution of RACH-based LTM includes CBRA-based LTM and CFRA-based LTM.

[0356] In specific implementation, the first node N51 can send the SR using the C-RNTI identifier in the first candidate target cell.

[0357] As an example, if the SR is not successfully sent, the SR is pending.

[0358] As an example, the SR being pending means that the SR is considered pending.

[0359] As an example, the SR being pending means that the SR is a pending SR.

[0360] As an example, the SR pending means that the SR process corresponding to the SR is in progress.

[0361] As an example, "SR pending" means that the SR is pending.

[0362] As an example, "SR pending" means that the SR is to be sent.

[0363] As an example, "SR pending" means that the SR is pending processing.

[0364] As an example, "cancel" refers to the act of canceling.

[0365] As an example, cancellation means ceasing processing.

[0366] As an example, cancellation means no longer pending transmission.

[0367] As an example, canceling the transmission of the SR to the first candidate target cell includes: canceling the SR process corresponding to the SR.

[0368] As an example, canceling the transmission of the SR to the first candidate target cell includes canceling the pending status of the SR.

[0369] As an example, canceling the transmission of the SR to the first candidate target cell includes: the SR is no longer considered pending.

[0370] As an example, the C-RNTI of the first node N51 in the first candidate target cell is the C-RNTI of the first node N51 in the source cell.

[0371] As an example, a field in the RRC signaling indicates the C-RNTI of the first node N51 in the first candidate target cell.

[0372] As an example, the C-RNTI of the first node N51 in the first candidate target cell is the C-RNTI of the first node in the cell group to which the first candidate target cell belongs.

[0373] As an example, the RRC signaling includes a field that is used to configure the timer.

[0374] In practice, the timer is T304.

[0375] In practice, the timer can be a timer for a MAC sublayer.

[0376] As an example, the MAC sublayer of the first node N51 can indicate the timer's expiration to the layer above the first node N51.

[0377] The scheme shown in Figure 6 is a possible transmission scheme that occurs during the execution of Embodiment 5. For more information on the working principle and working mode of the first node N51 in the application scenario shown in Figure 6, please refer to the relevant description in Figure 5 above, which will not be repeated here.

[0378] Example 7

[0379] Example 7 illustrates a wireless signal transmission flowchart according to yet another embodiment of the present invention, as shown in Figure 7.

[0380] Figure 7 is a schematic diagram of another feasible process executed by the first node N51 after executing step S514 to start the timer.

[0381] Specifically, after the timer starts, the first node N51 executes step S701 to determine if the timer has expired. If not, it executes step S702A to determine if the SR was successfully sent. If yes, it indicates that the SR was successfully sent, and then step S70A can be executed, including canceling the timer, i.e., executing step S516 as shown in Embodiment 5, and resetting the counter. If not, it proceeds to step S703B, i.e., resetting the timer.

[0382] In specific implementation, if the timer expires, the process proceeds to step S702B after step S701, i.e., updating the counter, for example, incrementing the counter by 1. Then, step S704 is executed to determine if the counter has reached its maximum value. If it has, step S705 is executed, i.e., the process of sending the SR to the first candidate target cell is canceled, and the RACH-based LTM is rolled back. If the maximum value has not been reached, the process proceeds to step S702A to determine if the SR was successfully sent, and then either step S703A or step S703B is executed based on the determination result.

[0383] The scheme shown in Figure 7 is another possible transmission scheme that appears during the execution of Embodiment 5. For more information on the working principle and working mode of the first node N51 in the application scenario shown in Figure 7, please refer to the relevant descriptions in Figures 1 to 6 above, which will not be repeated here.

[0384] As described above, the technical solution provided by the embodiments of the present invention allows the first node to send the SR to perform LTM cell handover without RACH, thus providing a possibility to ensure the robustness of conditional LTM.

[0385] Example 8

[0386] Example 8 illustrates a wireless signal transmission flowchart according to yet another embodiment of the present invention, as shown in Figure 8. It should be noted that the order in this example does not limit the signal transmission order or the order of implementation in the present invention.

[0387] Figure 8 illustrates a cell handover method suitable for application at a second node. The second node may be a sustaining node of the first candidate target cell, or a network device of the first candidate target cell, such as a base station device.

[0388] Specifically, the cell handover method may include:

[0389] Step S801: Receive the SR sent to the first candidate target cell;

[0390] Wherein, the receipt of the SR sent to the first candidate target cell depends on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-less LTM cell handover; the meaning of receiving the SR sent to the first candidate target cell depends on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-less LTM cell handover is: the SR is sent to the first candidate target cell only when the LTM cell handover performed is a RACH-less LTM cell handover.

[0391] The first node performing LTM cell handover is a response that satisfies the first execution condition, which is included in the configuration information of the first candidate target cell. The configuration information of the first candidate target cell is included in the RRC signaling sent from the source cell to the first node.

[0392] In practical implementation, whether the LTM cell handover is RACH-based LTM or RACH-free LTM depends on the RRC signaling. For RACH-based LTM, the RRC signaling may at least include relevant configuration information suitable for initiating a random access procedure in the first candidate target cell. For RACH-free LTM, the RRC signaling may at least include execution conditions and / or configuration information that can satisfy the initiation of RACH-free LTM.

[0393] In specific implementation, step S801 is the execution step after the first node successfully sends the SR. The first node may include the configuration information of the first candidate target cell in the RRC signaling sent by its source cell. The configuration information of the first candidate target cell includes the first execution condition. When the first node meets the first execution condition and determines to perform an LTM cell handover without RACH, the first node may send the SR to the first candidate target cell.

[0394] In a specific implementation, the configuration information of the first candidate target cell may include at least one candidate SR configuration, and each candidate SR configuration is associated with at least one SR resource; receiving the SR sent to the first candidate target cell includes: receiving the SR sent to the first candidate target cell on one of the at least one SR resources.

[0395] Whether the first candidate target cell has a chance to receive the SR is unknown. The uplink resource sent by the first node to the SR can be a PUCCH resource or a PUSCH resource. Preferably, the uplink resource is a PUCCH resource. The PUCCH resource can come from the candidate SR configuration sent by the source cell. The candidate SR configuration is included in the configuration information of the first candidate target cell.

[0396] As an example, the configuration information of the first candidate target cell may be determined through negotiation between the source cell and each candidate target cell.

[0397] Upon receiving the SR, the first candidate target cell can learn that the first node is about to complete or has already completed a RACH-free LTM cell handover. Then, the first candidate target cell becomes the first node's new serving cell. Furthermore, the new serving cell can send signaling to the first node to delete the context information of the previous source cell. Correspondingly, upon receiving the signaling, the first node can complete the deletion of the context information of the previous source cell.

[0398] In practice, the signaling can be an RRC reconfiguration message or a MAC CE.

[0399] Those skilled in the art will understand that step S801 can be considered as an execution step corresponding to the steps described in the embodiments shown in Figures 1, 5 to 7, and the two are complementary in their specific implementation principles and logic. Therefore, the cell handover method on the network side can be referred to the relevant descriptions of the embodiments shown in Figures 1, 5 to 7, and will not be repeated here.

[0400] Example 9

[0401] Example 9 illustrates yet another wireless signal transmission flowchart according to an embodiment of the present invention, as shown in Figure 9. It should be noted that the order in this example does not limit the signal transmission order or the order of implementation in the present invention.

[0402] Figure 9 illustrates a cell handover method suitable for application in a third node. The third node may be the sustaining node of the source cell of the first node, or it may be the network equipment of the source cell, such as a base station device.

[0403] Specifically, the method in the third node applicable to cell handover may include:

[0404] Step S901: Send RRC signaling to the first node.

[0405] The RRC signaling includes configuration information of at least a first candidate target cell; the configuration information of the first candidate target cell includes a first execution condition.

[0406] Wherein, when the first execution condition is met, the first node performs an LTM cell handover; and sends an SR to the first candidate target cell. The sending of the SR to the first candidate target cell depends on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-less LTM cell handover. The meaning of sending the SR to the first candidate target cell depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-less LTM cell handover is: the SR is sent only when the LTM cell handover being performed is a RACH-less LTM cell handover.

[0407] In specific implementation, in step S901, the source cell may send RRC signaling to the first node. The RRC signaling may be an RRC message. The RRC message may include configuration information of one or more candidate target cells, including the configuration information of the first candidate target cell.

[0408] As one embodiment, the configuration information of the first candidate target cell may include at least one candidate SR configuration, and each candidate SR configuration is associated with at least one SR resource. The SR resource is used to transmit the SR.

[0409] In specific implementation, whether the LTM cell handover is RACH-based LTM or RACH-free LTM depends on the RRC signaling. When the RRC signaling includes configuration information for RACH-based LTM, the first node can choose to perform cell handover using RACH-based LTM. When the RRC signaling includes configuration information for RACH-free LTM, the first node can choose to perform cell handover using RACH-free LTM.

[0410] Those skilled in the art will understand that step S901 can be considered as an execution step corresponding to the steps described in the embodiments shown in Figures 1, 5 to 8, and the two are complementary in their specific implementation principles and logic. Therefore, the cell handover method on the network side can be referred to the relevant descriptions of the embodiments shown in Figures 1, 5 to 8, and will not be repeated here.

[0411] Example 10

[0412] Example 10 illustrates a structural block diagram of a processing device in a first node according to an embodiment of the present invention, as shown in Figure 10. In Figure 10, the processing device 1000 in the first node includes a receiver 1001, a processor 1002, and a transmitter 1003.

[0413] In one embodiment, receiver 1001 receives RRC signaling sent by source cell, the RRC signaling including configuration information of at least a first candidate target cell; the configuration information of the first candidate target cell includes a first execution condition;

[0414] Processor 1002, in response to the fulfillment of the first execution condition, performs LTM cell handover;

[0415] Transmitter 1003 initiates the process of sending an SR (scheduling request) to the first candidate target cell. The process of initiating the sending of the SR to the first candidate target cell depends on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover.

[0416] The meaning of "the process of initiating the sending of SR to the first candidate target cell depends on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover" is that the process of initiating the sending of SR to the first candidate target cell is performed only when the LTM cell handover performed is a RACH-free LTM cell handover.

[0417] As an example, whether the LTM cell handover is RACH-based LTM or RACH-free LTM depends on the RRC signaling.

[0418] As an example, the process of initiating the sending of an SR to the first candidate target cell includes attempting to send an SR.

[0419] As an example, the transmission of the SR is independent of whether there is data to be transmitted.

[0420] As an example, the transmission of the SR is independent of whether there is a MAC CE to be transmitted.

[0421] As an example, the transmission of the SR does not depend on whether there is data to be transmitted.

[0422] As an example, the transmission of the SR does not depend on whether there is a pending MAC CE.

[0423] As an example, the SR is not associated with any data.

[0424] As an example, the SR is not associated with any MAC CE.

[0425] As an example, the process of initiating the sending of SR to the first candidate target cell is performed after the LTM cell handover begins.

[0426] As an example, the process of initiating the sending of SR to the first candidate target cell is performed before the LTM cell handover is completed.

[0427] As an example, the first node does not require listening to the PDCCH of the first candidate target cell before the SR is sent.

[0428] As an example, the advantages of the above method include: saving PDCCH resources, saving power, and reducing interference to other nodes.

[0429] As an example, in response to receiving the PDCCH scheduling of the first candidate target cell, the process of sending the SR to the first candidate target cell is cancelled.

[0430] As an example, in response to receiving a PDCCH schedule from any of the first candidate target cells, the process of sending an SR to the first candidate target cell is cancelled.

[0431] As an example, the SR is the first SR sent to the first candidate target cell.

[0432] As an example, the SR is the first signal sent to the first candidate target cell.

[0433] In specific implementation, the transmitter 1003 can trigger the SR synchronously based on the physical layer of the first candidate target cell and send the SR to the first candidate target cell.

[0434] In a specific implementation, the transmitter 1003 can start a timer when the SR is triggered; when the timer expires, the process of sending the SR to the first candidate target cell is canceled, and the RACH-based LTM is rolled back.

[0435] As an example, the rollback execution of RACH-based LTM only includes CBRA-based LTM.

[0436] As an example, the advantages of the above method include: using CBRA is more reliable and not limited by resources and initiation time.

[0437] As an example, the rollback execution of RACH-based LTM includes CBRA-based LTM and CFRA-based LTM.

[0438] As an example, the benefits of the above methods include: the benefits of using CBRA and CFRA include: increasing the probability of successful random access.

[0439] In a specific implementation, the transmitter 1003 can be used to send an SR to the first candidate target cell during the operation of the timer and then cancel the timer; wherein, the SR is the first uplink signal sent by the first node to the first candidate target cell.

[0440] In a specific implementation, the transmitter 1003 can update the counter when the SR transmission fails; when the counter reaches a preset value, the counter is reset, and the process of sending the SR to the first candidate target cell is canceled, and the RACH-based LTM is rolled back; wherein, the counter is used to record the number of SR transmission failures.

[0441] In a specific implementation, the configuration information of the first candidate target cell includes at least one candidate SR configuration, and each candidate SR configuration is associated with at least one SR resource; the transmitter 1003 can be used to send an SR to the first candidate target cell through one of the at least one SR resources.

[0442] In practice, whether the LTM cell handover is RACH-based LTM or RACH-free LTM depends on the RRC signaling.

[0443] As an example, the receiver 1001 includes an antenna 452, a receiver 454, a multi-antenna receiving processor 458, a receiving processor 456, a controller / processor 459, a memory 460, and a data source 467, as shown in Figure 4 of this invention.

[0444] As an example, the receiver 1001 includes the antenna 452, receiver 454, multi-antenna receiver processor 458, and receiver processor 456 shown in Figure 4 of this invention.

[0445] As an example, the receiver 1001 includes the antenna 452, receiver 454, and receiver processor 456 shown in Figure 4 of this invention.

[0446] As an example, the transmitter 1003 may include the antenna 452, transmitter 454, multi-antenna transmission processor 457, transmission processor 468, controller / processor 459, memory 460 and data source 467 shown in Figure 4 of this invention.

[0447] As an example, the transmitter 1003 may include the antenna 452, transmitter 454, multi-antenna transmission processor 457, and transmission processor 468 shown in Figure 4 of this invention.

[0448] As an example, the transmitter 1003 may include the antenna 452, transmitter 454, and transmission processor 468 shown in Figure 4 of this invention.

[0449] For more information on the working principle and operation mode of the processing device 1000 in the first node, please refer to the relevant description of the technical solutions shown in Figures 1 to 7 above, which will not be repeated here.

[0450] Example 11

[0451] Example 11 illustrates a structural block diagram of a processing device in a second node according to an embodiment of the present invention, as shown in Figure 11. In Figure 11, the processing device 1100 in the second node includes a receiver 1101. The processing device 1100 in the second node can be executed by a network side, such as base station equipment.

[0452] As an example, receiver 1101 receives an SR, the SR depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover; the meaning of the SR depending on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover is: the SR is sent only when the LTM cell handover being performed is a RACH-free LTM cell handover; wherein, the SR is triggered by the satisfaction of a first execution condition, the first execution condition being included in the configuration information of a first candidate target cell, and the configuration information of the first candidate target cell being included in the RRC signaling from the source cell to the sender of the SR.

[0453] In specific implementation, the configuration information of the first candidate target cell includes at least one candidate SR configuration, and each candidate SR configuration is associated with at least one SR resource.

[0454] As an example, the receiver 1001 receives the SR sent to the first candidate target cell on one of the at least one SR resources.

[0455] In practice, whether the LTM cell handover is RACH-based LTM or RACH-free LTM depends on the RRC signaling.

[0456] As an example, the receiver 1101 includes an antenna 420, a receiver 418, a multi-antenna receiving processor 472, a receiving processor 470, a controller / processor 475, and a memory 476, as shown in Figure 4 of this invention.

[0457] As an example, the receiver 1101 includes the antenna 420, receiver 418, multi-antenna receiver processor 472, and receiver processor 470 shown in Figure 4 of this invention.

[0458] As an example, the receiver 1101 includes the antenna 420, receiver 418, and receiver processor 470 shown in Figure 4 of this invention.

[0459] For more information on the working principle and operation mode of the processing device 1100 in the second node, please refer to the relevant description of the technical solutions shown in Figures 1 to 7 above, which will not be repeated here.

[0460] Example 12

[0461] Example 12 illustrates a structural block diagram of a processing device in a third node according to an embodiment of the present invention; as shown in Figure 12. In Figure 12, the processing device 1200 in the third node includes a transmitter 1201. The processing device 1200 in the third node can be executed by a network side, such as base station equipment.

[0462] In specific implementation, the transmitter 1201 is used to send RRC signaling to the first node. The RRC signaling includes configuration information of at least a first candidate target cell. The configuration information of the first candidate target cell includes a first execution condition. When the first execution condition is met, the first node performs an LTM cell handover and sends an SR to the first candidate target cell. The sending of the SR to the first candidate target cell depends on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-less LTM cell handover. The meaning of sending the SR to the first candidate target cell depending on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-less LTM cell handover is: the SR is sent only when the LTM cell handover performed is a RACH-less LTM cell handover.

[0463] As an example, the transmitter 1201 includes the antenna 420, transmitter 418, multi-antenna transmission processor 471, transmission processor 416, controller / processor 475, and memory 476 shown in Figure 4 of this invention.

[0464] As an example, the transmitter 1201 includes the antenna 420, transmitter 418, multi-antenna transmission processor 471, and transmission processor 416 shown in Figure 4 of this invention.

[0465] As an example, the transmitter 1201 includes the antenna 420, transmitter 418, and transmission processor 416 shown in Figure 4 of this invention.

[0466] For more information on the working principle and operation mode of the processing device 1200 in the third node, please refer to the relevant description of the technical solutions shown in Figures 1 to 7 above, which will not be repeated here.

[0467] Those skilled in the art will understand that all or part of the steps in the above methods can be implemented by a program instructing related hardware, and the program can be stored in a computer-readable storage medium, such as a read-only memory, hard disk, or optical disk. Optionally, all or part of the steps in the above embodiments can also be implemented using one or more integrated circuits. Correspondingly, each module unit in the above embodiments can be implemented in hardware or in the form of software functional modules. This invention is not limited to any specific combination of software and hardware. The user equipment, terminal, and UE in this invention include, but are not limited to, drones, communication modules on drones, remote-controlled aircraft, aircraft, small aircraft, mobile phones, tablet computers, laptops, vehicle-mounted communication devices, wireless sensors, internet access cards, IoT terminals, RFID terminals, NB-IoT terminals, MTC (Machine Type Communication) terminals, eMTC (enhanced MTC) terminals, data cards, internet access cards, vehicle-mounted communication devices, low-cost mobile phones, low-cost tablet computers, and other wireless communication devices. The base stations or system equipment in this invention include, but are not limited to, macrocell base stations, microcell base stations, home base stations, relay base stations, gNB (NR Node B), TRP (Transmitter Receiver Point), and other wireless communication equipment.

[0468] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A first node for controlling SR transmission during LTM cell handover, characterized in that, include: The receiver receives RRC signaling sent by the source cell, the RRC signaling including configuration information of at least the first candidate target cell; The configuration information of the first candidate target cell includes the first execution condition; The processor, in response to the fulfillment of the first execution condition, performs an LTM cell handover; The transmitter initiates the process of sending an SR (scheduling request) to the first candidate target cell. The process of initiating the sending of the SR to the first candidate target cell depends on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover. The meaning of "the process of initiating the sending of SR to the first candidate target cell depends on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover" is that the process of initiating the sending of SR to the first candidate target cell is performed only when the LTM cell handover performed is a RACH-free LTM cell handover.

2. The first node according to claim 1, characterized in that, Send SR to the first candidate target cell to synchronize with the first candidate target cell.

3. The first node according to claim 1 or 2, characterized in that, include: The transmitter starts a timer during the process of initiating the transmission of SR to the first candidate target cell; As the timer expires, the process of sending the SR to the first candidate target cell is cancelled, and the execution of RACH-based LTM is rolled back.

4. The first node according to claim 3, characterized in that, include: The transmitter, after sending an SR to the first candidate target cell during the timer's operation, stops the timer; Wherein, SR is the first uplink signal sent by the first node to the first candidate target cell.

5. The first node according to claim 1 or 2, characterized in that, include: The transmitter updates its counter in response to its failure to send an SR to the first candidate target cell; When the counter reaches a preset value, the counter is reset, and the process of sending SR to the first candidate target cell is canceled, and the RACH-based LTM is rolled back. The counter is used to record the number of SR transmission failures.

6. The first node according to any one of claims 1 to 5, characterized in that, include: The transmitter sends an SR to the first candidate target cell on one of the at least one SR resources; The configuration information of the first candidate target cell includes at least one candidate SR configuration, and each candidate SR configuration is associated with at least one SR resource.

7. The first node according to claim 6, characterized in that, include: The receiver receives an RRC reconfiguration message for the first candidate target cell. The RRC reconfiguration message includes deleting the context information of the source cell and retaining the configuration information of at least the first candidate target cell.

8. The first node according to any one of claims 1 to 7, characterized in that, Whether the LTM cell handover is RACH-based LTM or RACH-free LTM depends on the RRC signaling.

9. The first node according to any one of claims 1 to 8, characterized in that, The first execution condition includes: the quality of the first candidate target cell is better than a given threshold; and the configuration information of the first candidate target cell includes the given threshold.

10. A method for controlling SR transmission in the first node during LTM cell handover, characterized in that, include: Receive RRC signaling sent by the source cell, the RRC signaling including at least the configuration information of the first candidate target cell; The configuration information of the first candidate target cell includes the first execution condition; In response to the fulfillment of the first execution condition, an LTM cell handover is performed; The process of initiating the sending of SR to the first candidate target cell depends on whether the LTM cell handover being performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover. The meaning of "the process of initiating the sending of SR to the first candidate target cell depends on whether the LTM cell handover performed is a RACH-based LTM cell handover or a RACH-free LTM cell handover" is that the process of initiating the sending of SR to the first candidate target cell is performed only when the LTM cell handover performed is a RACH-free LTM cell handover.

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