Method and communication device for handling re-establishment procedures

Abstract

The present invention provides a method and a communication device for handling re-establishment procedures. [Solution] A method for a communication device to process a re-establishment procedure includes: initiating a re-establishment procedure; selecting a target cell according to a cell selection procedure; triggering an OD-SIB1 procedure on the target cell according to a stored wake-up signal (WUS) configuration, depending on whether at least one on-demand system information block 1 (OD-SIB1) procedure trigger condition is met; selecting an OD-SIB1 request from a preamble pool; sending an OD-SIB1 request to the target cell in an uplink (UL) resource within the OD-SIB1 procedure; determining whether the target cell is a cell on which the communication device can camp-on, according to the SIB1 from the target cell; and sending a re-establishment request message to the target cell, depending on whether the target cell is a cell on which the communication device can camp-on.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of U.S. Provisional Application No. 63 / 747,898, filed on January 22, 2025. The content of the application is incorporated herein by reference.

[0002] The present disclosure relates to methods and communication devices used in wireless communication systems, and more particularly, to methods and communication devices for handling re - establishment procedures.

Background Art

[0003] The Long Term Evolution (LTE) system that supports the 3rd Generation Partnership Project (3GPP (registered trademark)) Rel - 8 standard and / or 3GPP Rel - 9 standard has been developed by 3GPP as a successor to the Universal Mobile Telecommunications System (UMTS) to further enhance the performance of UMTS to meet the increasing needs of users.

[0004] The Long Term Evolution - Advanced (LTE - A) system is an evolved version of the LTE system, as its name suggests. The LTE - A system aims for faster switching between power states, improves performance at the edge of the coverage of evolved Node - B (eNB), improves peak data rate and throughput, and includes advanced technologies such as carrier aggregation (CA), uplink (UL) multiple - input multiple - output (UL - MIMO).

[0005] To further enhance the LTE-A system, next-generation radio access networks (NG-RANs) supporting 3GPP Rel-15 to 3GPP Rel-19 standards are being developed. An NG-RAN includes one or more next-generation Node-Bs (gNBs) and features characteristics such as wider operating bandwidth, different numerologies across different frequency ranges, massive MIMO, and advanced channel coding.

[0006] A communication device requires a System Information Block 1 (SIB1) provided by a cell to check whether the cell is suitable for the communication device to perform a re-establishment procedure. If an SIB1 is not available, the communication device requests an SIB1 from the cell by performing an OD-SIB1 procedure according to the Wake-Up Signal (WUS) configuration. However, the communication device may not successfully re-establish the connection to the cell due to, for example, an invalid WUS configuration and / or delays caused by the execution of the OD-SIB1 procedure. [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, how to handle the re-establishment procedure is a crucial issue that needs to be resolved. [Means for solving the problem]

[0008] Therefore, to solve the above-mentioned problems, this disclosure provides a method and a communication device for handling a re-establishment procedure.

[0009] A communication device method for handling a re-establishment procedure includes the steps of: initiating a re-establishment procedure; selecting a target cell according to a cell selection procedure; triggering an OD-SIB1 procedure on the target cell according to a stored wake-up signal (WUS) configuration, depending on whether at least one On-Demand System Information Block 1 (OD-SIB1) procedure trigger condition is met; selecting an OD-SIB1 request from a preamble pool; sending an OD-SIB1 request to the target cell in an uplink (UL) resource within the OD-SIB1 procedure; determining whether the target cell is a cell on which the communication device can camp-on, according to an SIB1 from the target cell; and sending a re-establishment request message to the target cell, depending on whether the target cell is a cell on which the communication device can camp-on.

[0010] A serving cell method for handling a re-establishment procedure includes the step of sending a Wake-Up Signal (WUS) configuration set to a communication device, the WUS configuration set including multiple identities (IDs) for multiple cells, multiple frequencies corresponding to multiple cells, and multiple WUS configurations corresponding to multiple cells, where multiple cells include serving cells.

[0011] A network energy saving (NES) cell method for handling a re-establishment procedure includes the steps of: performing an OD-SIB1 procedure with a communication device according to a stored wake-up signal (WUS) configuration in response to the fulfillment of at least one on-demand system information block 1 (OD-SIB1) procedure trigger condition; and the NES cell receiving a re-establishment request message from a communication device in response to the communication device being a camp-on cell, wherein the step of performing the OD-SIB1 procedure includes receiving an OD-SIB1 request from a communication device on an uplink (UL) resource.

[0012] These and other objectives of the present invention will undoubtedly become apparent to those skilled in the art after reading the following detailed description of preferred embodiments shown in various figures and drawings. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram of a wireless communication system according to an example of the disclosure. [Figure 2] This is a schematic diagram of a communication device as an example of the disclosure. [Figure 3] This is a flowchart illustrating the process as described in this disclosure. [Figure 4] This is a flowchart illustrating the process as described in this disclosure. [Figure 5] This is a flowchart illustrating the process as described in this disclosure. [Figure 6] This is a sequence diagram of a process according to the examples in this disclosure. [Figure 7] This is a sequence diagram of a process according to the examples in this disclosure. [Figure 8] This is a sequence diagram of a process according to the examples in this disclosure. [Figure 9] This is a flowchart illustrating the process as described in this disclosure. [Figure 10] This is a flowchart illustrating the process as described in this disclosure. [Figure 11] This is a sequence diagram of a process according to the examples in this disclosure. [Figure 12] This diagram shows a schematic representation of a specific period for verifying whether a stored WUS configuration is valid, as illustrated by the examples in this disclosure. [Figure 13] This diagram shows a schematic representation of a specific period for verifying whether a stored WUS configuration is valid, as illustrated by the examples in this disclosure. [Modes for carrying out the invention]

[0014] Figure 1 is a schematic diagram of a wireless communication system 10 according to an example of the present disclosure. Briefly, the wireless communication system 10 consists of a network 12 and a plurality of communication devices 14. The wireless communication system 10 may support time-division duplex (TDD) mode, frequency-division duplex (FDD) mode, TDD-FDD joint operation mode, non-terrestrial network (NTN) mode, or licensed-assisted access (LAA) mode. That is, the network 12 and communication devices 14 may communicate with each other via FDD carriers, TDD carriers, licensed carriers (licensed serving cells), and / or unlicensed carriers (unlicensed serving cells). Furthermore, the wireless communication system 10 may support carrier aggregation (CA). That is, the network 12 and communication devices 14 may communicate with each other via a plurality of serving cells (e.g., a plurality of serving carriers), including a primary cell (e.g., a primary component carrier) and one or more secondary cells (e.g., secondary component carriers).

[0015] In Figure 1, the network 12 and communication device 14 are used simply to illustrate the structure of the wireless communication system 10. In practice, network 12 may be a universal terrestrial radio access network (UTRAN) including at least one Node-B (NB) of a universal mobile communications system (UMTS). For example, network 12 may be an evolved UTRAN (E-UTRAN) including at least one evolved NB (eNB) and / or at least one relay node, such as a Long-Term Evolution (LTE) system, an LTE-Advanced (LTE-A) system, or an evolved version of the LTE-A system. For example, network 12 may be a next-generation radio access network (NG-RAN) including at least one next-generation Node-B (gNB) and / or at least one fifth-generation (5G) base station (BS). For example, the gNB or 5G BS of network 12 may include an NTN gateway and an NTN payload. In one example, the gNB or 5G BS of network 12 may be a transmission reception point (TRP). In another example, network 12 may be any BS that conforms to a specific communication standard for communicating with the communication device 14.

[0016] New Radio (NR) is a standard defined for 5G systems (or 5G networks) to provide a unified radio interface with better performance. gNBs are deployed to implement 5G systems that support advanced features such as enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine type communications (mMTC). eMBB provides broadband services with wider bandwidth and low / medium latency. URLLC provides applications with higher reliability and low latency characteristics (such as end-to-end communication). Examples of applications include industrial Internet, smart grid, infrastructure protection, remote surgery, and advanced road traffic systems (ITS). mMTC can support the Internet of Things (IoT) of 5G systems including billions of connected devices and / or sensors.

[0017] Furthermore, network 12 may include at least one of UTRAN / E-UTRAN / NG-RAN and a core network, the core network may include network entities such as a mobility management entity (MME), a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), a self-organizing network (SON) server and / or a wireless network controller (RNC), an access and mobility management function (AMF), a session management function (SMF), a user plane function (UPF), and an authentication server function (AUSF). In one example, after network 12 receives information transmitted by communication device 14, the information may be processed only by UTRAN / E-UTRAN / NG-RAN, and decisions corresponding to the information may be made in UTRAN / E-UTRAN / NG-RAN. In another example, UTRAN / E-UTRAN / NG-RAN may forward the information to the core network, and decisions corresponding to the information may be made in the core network after the core network has processed the information. In one example, information may be processed by both UTRAN / E-UTRAN / NG-RAN and the core network, and decisions are made after coordination and / or cooperation are performed by UTRAN / E-UTRAN / NG-RAN and the core network.

[0018] The communication device 14 may be a user equipment (UE), a very small aperture terminal (VSAT), a low-cost device (e.g., a machine type communication (MTC) device), a device-to-device (D2D) communication device, a narrowband Internet of Things (NB-IoT), a mobile phone, a laptop, a tablet computer, an e-book, a portable computer system, or a combination thereof. Further, the network 12 and the communication device 14 can be regarded as a transmitter or a receiver according to the direction (i.e., the transmission direction). For example, regarding the uplink (UL), the communication device 14 is the transmitter and the network 12 is the receiver, and regarding the downlink (DL), the network 12 is the transmitter and the communication device 14 is the receiver.

[0019] The communication device 14 may perform layer 1 (L1) measurements to generate L1 measurement results and may change the serving cell according to the L1 measurement results. This procedure may be called conditional L1 / L2 triggered mobility (C-LTM). C-LTM may support intra-gNB-distributed unit (intra-gNB-DU) mobility, intra-gNB-central unit (intra-gNB-CU) mobility, and / or inter-gNB-DU mobility. C-LTM may support in-band mobility and / or inter-band mobility. C-LTM may be supported for licensed spectrum. C-LTM may support at least one of the following scenarios, i.e., the change of the primary cell (PCell) in a non-carrier aggregation (non-CA) scenario or / and a non-dual connectivity (non-DC) scenario, the change of the PCell and the secondary cell (SCell) in a CA scenario, and at least one of the DC scenarios. The communication device 14 may execute an L3 handover command transmitted by the network 12.

[0020] Figure 2 is a schematic diagram of a communication device 20 according to an example of the present disclosure. The communication device 20 may be, but is not limited to, the communication device 14 or network 12 shown in Figure 1. The communication device 20 may include at least one processing circuit 200, such as a microprocessor or application-specific integrated circuit (ASIC), at least one storage device 210, and at least one communication interface device 220. The at least one storage device 210 may be any data storage device that can store program code 214 accessed and executed by at least one processing circuit 200. Examples of the at least one storage device 210 include, but are not limited to, subscriber identification modules (SIMs), read-only memory (ROMs), flash memory, random access memory (RAMs), compact disc read-only memory (CD-ROMs), digital versatile disc ROMs (DVD-ROMs), Blu-ray disc ROMs (BD-ROMs), magnetic tape, hard disks, optical data storage devices, non-volatile storage devices, and non-transient computer-readable media (e.g., tangible media). At least one communication interface device 220 is preferably at least one transceiver, which is used to transmit and receive signals (e.g., data, messages, and / or packets) according to the processing results of at least one processing circuit 200.

[0021] Figure 3 is a flowchart of process 30 according to an example of the present disclosure. Process 30 may be used in a communication device (for example, communication device 14 in Figure 1 or communication device 20 in Figure 2) to handle a re-establishment procedure. Process 30 may be compiled into program code 214, which includes the following steps:

[0022] Step 300: Start.

[0023] Step 302: Initiate the re-establishment procedure.

[0024] Step 304: Follow the cell selection procedure to select the target cell.

[0025] Step 306: When at least one On-Demand System Information Block 1 (OD-SIB1) procedure trigger condition is met, trigger the OD-SIB1 procedure on the target cell according to the stored Wake-Up Signal (WUS) configuration.

[0026] Step 308: Select the OD-SIB1 request from the preamble pool.

[0027] Step 310: In the OD-SIB1 procedure, the UL resource sends an OD-SIB1 request to the target cell.

[0028] Step 312: Based on the SIB1 from the target cell, the target cell determines whether or not it is a cell on which a communication device can be camped.

[0029] Step 314: Depending on whether the target cell is a cell that can camp on the communication device, the target cell sends a re-establishment request message to the target cell.

[0030] Step 314: Finish.

[0031] According to process 30, the communication device initiates a re-establishment procedure. The communication device then selects a target cell according to the cell selection procedure. The communication device triggers (and executes) an OD-SIB1 procedure on the target cell according to the stored WUS configuration, depending on whether at least one OD-SIB1 procedure trigger condition (e.g., all OD-SIB1 procedure trigger conditions) is met. The communication device selects an OD-SIB1 request (e.g., a preamble) from the preamble pool and sends the OD-SIB1 request to the target cell in the UL resource within the OD-SIB1 procedure. The communication device determines, based on the SIB1 from the target cell, whether the target cell is a cell on which the communication device can camp on. The communication device sends a re-establishment request message (e.g., Msg3) to the target cell, depending on whether the target cell is a cell on which the communication device can camp on.

[0032] The implementation of process 30 is not limited to the above description. The following examples may be applied to implement process 30.

[0033] In one example, the cell on which the communication device can camp on is the highest-ranked cell based on measurements. In another example, the stored WUS configuration is included in the WUS configuration set. In another example, the WUS configuration set is received from the serving cell of the communication device and stored in the communication device.

[0034] In one example, at least one OD-SIB1 procedure trigger condition includes at least one of the following conditions: the target cell does not provide SIB1 (e.g., periodically), the target cell is a Network Energy Saving (NES) cell, and the stored WUS configuration is enabled. In one example, SIB1 includes at least one of the following information: public land mobile network (PLMN) information, other SIB availability and scheduling, and access control information. In one example, PLMN information is used to determine whether the target cell is a cell on which communication devices can camp. In one example, an NES cell provides OD-SIB1 on demand (i.e., does not provide OD-SIB1 periodically). In one example, at least one OD-SIB1 procedure trigger condition includes at least one of the following conditions: the target cell supports the OD-SIB1 procedure.

[0035] In one example, the communication device verifies whether a stored WUS configuration is valid. In one example, the step of verifying whether a stored WUS configuration is valid includes at least one of the following steps: determining that the stored WUS configuration is valid depending on whether the system frame number (SFN) of the current radio frame is within a specific period (e.g., WUS_ValidPeriod); and determining that the stored WUS configuration is invalid at the end of the specific period. In one example, the step of verifying whether a stored WUS configuration is valid includes determining that the stored WUS configuration is invalid depending on whether the SFN of the current radio frame is outside the specific period. In one example, the step of verifying whether a stored WUS configuration is valid includes determining that the stored WUS configuration is invalid in response to the start of a re-establishment procedure.

[0036] In one example, a communication device determines the end of a particular period. In one example, the step of determining the end of a particular period includes receiving a configured system information (SI) change instruction from a serving cell during the modification period and ending the particular period at the boundary of the modification period. That is, the communication device determines the end of a particular period by whether or not it receives an SI change instruction during the modification period. In one example, the SI change instruction is broadcast (e.g., via a short message). In one example, the boundary of the modification period is the end of the modification period. In one example, the boundary of the modification period is defined by at least one SFN value. In one example, the SFN value is divisible by the number of radio frames (RFs) that make up the modification period. In one example, the number of RFs is the product of the modification period coefficient and the default paging cycle. In one example, the modification period coefficient is 2, 4, 8, or 16, but is not limited herein. In one example, the communication device ends a particular period at the boundary of the next modification period in response to an unconfigured SI change instruction. In one example, the boundary of the next modification period is the end of the next modification period. In one example, a communication device terminates a specific period at the boundary of a correction period, in accordance with the configured SI change instruction.

[0037] In one example, the communication device checks whether an SI change instruction has been set to determine the range of a specific period. In another example, the communication device monitors for an SI change instruction when a third timer (e.g., T310) is running if a radio link failure (RLF) condition occurs. In yet another example, the communication device monitors for an SI change instruction at the beginning of each correction period.

[0038] In one example, the UL resource is a Random Access (RA) resource. In one example, an OD-SIB1 request is used to inform a target cell that an OD-SIB1 procedure is being triggered. In one example, a communication device is configured by the serving cell using a preamble pool. In one example, the communication device randomly selects a preamble from the preamble pool as an OD-SIB1 request. In one example, a communication device is configured by the serving cell using a set of Random Access Opportunities (ROs). In one example, the communication device selects an RO (for example, randomly) from the RO set to send an OD-SIB1 request to the target cell.

[0039] In one example, the OD-SIB1 procedure includes at least one of the following steps: starting a watch window; watching (e.g., receiving) an OD-SIB1 request acknowledgment (ACK) (e.g., a random access response (RAR) or a media access control (MAC) control element (CE)) during the watch window; and stopping the watch window in response to receiving an OD-SIB1 request ACK from the target cell. In other words, the communication device performs the OD-SIB1 procedure to request the target cell to provide an OD-SIB1.

[0040] In one example, the step of monitoring the OD-SIB1 request ACK in a monitoring window includes determining (e.g., releasing) the stored WUS configuration in response to the expiration of the monitoring window. In another example, the step of monitoring the OD-SIB1 request ACK in a monitoring window includes at least one of the following steps: resending the OD-SIB1 request to the target cell in response to the expiration of the monitoring window; incrementing the value of a counter by 1 in response to the resending of the OD-SIB1 request to the target cell; and determining that the target cell is a barring cell (e.g., a cell from which a communication device cannot camp on) in response to the counter value being greater than a threshold (e.g., ReEst-preambleTransMax). That is, if the communication device does not receive the OD-SIB1 request ACK from the target cell, it resends the OD-SIB1 request to the target cell. In another example, the communication device determines (e.g., declares) a failure of the OD-SIB1 procedure in response to the counter value being greater than a threshold. In one example, the threshold may be 0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 20, 50, 100, or 200, but is not limited herein. In one example, the value of the counter represents the number of retries for the communication device to perform the OD-SIB1 procedure.

[0041] In one example, the step of monitoring an OD-SIB1 request ACK in a monitoring window includes at least one of the following steps: determining (e.g., declaring) that the OD-SIB1 procedure has failed in response to the communication device not receiving an OD-SIB1 request ACK in the monitoring window; retransmitting the OD-SIB1 request to the target cell in response to the determination (e.g., declaration) that the OD-SIB1 procedure has failed; incrementing a counter value by 1 in response to the retransmission of the OD-SIB1 request to the target cell; and determining that the target cell is a prohibited cell (e.g., a cell from which the communication device cannot camp on) in response to the counter value being greater than a threshold (e.g., ReEst-preambleTransMax).

[0042] In one example, the OD-SIB1 request ACK is used to inform the communication device that the OD-SIB1 request has been received by the target cell. In one example, the OD-SIB1 request ACK includes at least one of the following data: a timing advance (TA) value, resources for the re-establishment request message, the identity of the communication device, and information about the SIB1. In one example, the OD-SIB1 procedure further includes the following step: monitoring the SIB1 in response to monitoring the OD-SIB1 request ACK. In one example, the TA value is used for UL synchronization. In one example, the identity of the communication device includes a random access preamble identity (RAPID) or UE temperate ID.

[0043] In one example, the OD-SIB1 request ACK includes the OD-SIB1. That is, to reduce the delay caused by the execution of the OD-SIB1 procedure, the target cell does not need to send an additional OD-SIB1 to the communication device. In one example, the OD-SIB1 in the OD-SIB1 request ACK is a complete OD-SIB1. In one example, the complete OD-SIB1 includes target cell information (e.g., PLMN information) and at least one of SIB availability information, SIB scheduling information, and access control information. The target cell information is used by the communication device to determine whether the target cell is a cell that the communication device can camp on to. In one example, the OD-SIB1 in the OD-SIB1 request ACK is a simplified OD-SIB1. In one example, the simplified OD-SIB1 includes target cell information (e.g., only). In one example, the communication device determines whether the target cell is a cell that the communication device can camp on to according to the OD-SIB1 in the OD-SIB1 request ACK. In one example, the communication device determines that the target cell is a prohibited cell because it is not a cell on which the communication device can camp-on, and then re-selects a different target cell according to the cell selection procedure.

[0044] In one example, OD-SIB1 is broadcast by the target cell to reduce signal overhead. In one example, the OD-SIB1 procedure includes at least one of the following steps: starting an OD-SIB1 monitoring window; monitoring (e.g., receiving) OD-SIB1 in the OD-SIB1 monitoring window; and stopping the OD-SIB1 monitoring window in response to receiving an OD-SIB1 from the target cell. In one example, the OD-SIB1 procedure includes at least one of the following steps: retransmitting an OD-SIB1 request to the target cell in response to the communication device not receiving an OD-SIB1 in the OD-SIB1 monitoring window; determining that the target cell is a prohibited cell in response to the number of retries the communication device has attempted to retransmit the OD-SIB1 request exceeding an OD-SIB1 request threshold; and re-selecting a different target cell in response to the number of retries exceeding the OD-SIB1 request threshold. In one example, the OD-SIB1 request threshold represents the maximum number of retries the communication device will attempt to retransmit an OD-SIB1 request.

[0045] In one example, a UL resource for sending a re-establishment request message is allocated by the OD-SIB1 request ACK. In this example, the UL resource allocated by the OD-SIB1 request ACK is after the DL resource for receiving the OD-SIB1.

[0046] For example, a communication device determines (for instance, declares) that a re-establishment request message collision has occurred if the communication device and at least one other communication device receive the same OD-SIB1 request ACK.

[0047] In one example, the communication device starts a fourth timer in response to sending a re-establishment request message to the target cell. In another example, the communication device determines (for example, declares) that a re-establishment request message collision has occurred when the fourth timer expires.

[0048] In one example, a communication device determines (for example, declares) that a collision occurs in a re-establishment request message if the resolution ID in the re-establishment message is not the same as the resolution ID in the re-establishment request message. In one example, the resolution ID in the re-establishment request message is the identity of the communication device. In another example, the resolution ID in the re-establishment request message is a sequence number selected (for example, randomly) by the communication device.

[0049] In one example, a communication device resends a re-establishment request message to the target cell in response to a determination (e.g., a declaration) that a re-establishment request message collision has occurred.

[0050] In one example, the communication device starts a first timer (e.g., T310) in response to detecting a problem with the wireless link. In another example, the communication device stops the first timer in response to resolving the wireless link problem. In yet another example, the communication device declares an RLF (Reconnection Limiter) in response to the expiration of the first timer. In yet another example, the communication device initiates a re-establishment procedure in response to the RLF declaration.

[0051] In one example, a communication device enters idle mode from connected mode in response to a failed re-establishment procedure. In another example, the communication device restores connectivity (for example, from a serving cell to a target cell) in response to a successful re-establishment procedure.

[0052] In one example, the communication device starts a second timer (e.g., T311) in response to the start of the re-establishment procedure. In another example, the communication device stops the second timer when the re-establishment procedure is complete (e.g., the communication device successfully camps on to the target cell). In yet another example, the communication device determines (e.g., declares) that the re-establishment procedure has failed when the second timer expires.

[0053] In one example, a communication device sends a re-establishment request message to a target cell and then receives a re-establishment message (e.g., Msg4) from the target cell. In another example, the communication device camps on to the target cell according to the re-establishment message (e.g., re-establishes the connection to the target cell). In yet another example, a communication device sends a re-establishment request message to a target cell and then receives a setup message (e.g., Msg4) from the target cell. In yet another example, the communication device camps on to the target cell according to the setup message (e.g., sets up the connection to the target cell).

[0054] In one example, a communication device receives a WUS configuration set from a serving cell. In one example, the WUS configuration set is received via an SIB. In one example, after receiving the WUS configuration set, the communication device stores the WUS configuration set. In one example, the WUS configuration set includes multiple identities (IDs) for multiple cells, multiple frequencies corresponding to (for example, each of) multiple cells, and multiple WUS configurations corresponding to (for example, each of) multiple cells.

[0055] In one example, a WUS configuration set further includes multiple instructions corresponding to multiple WUS configurations (for example, each of them). In one example, each of the instructions indicates whether the corresponding WUS configuration is supported by a connected mode communication device. In one example, the communication device receives a cell list from a serving cell. In one example, the cell list indicates which WUS configurations in the WUS configuration set are supported by the connected mode communication device.

[0056] In one example, the communication device determines that a target cell is not a cell that the communication device can camp on to, based on the fact that the target cell does not support the OD-SIB1 procedure. In another example, the communication device adds the condition "the target cell supports the OD-SIB1 procedure" to at least one OD-SIB1 procedure trigger condition, based on the fact that the target cell does not support the OD-SIB1 procedure.

[0057] In one example, the communication device sends an OD-SIB1 request to the target cell once. In another example, the communication device determines that the target cell is not a cell on which the communication device can camp on, based on the fact that the communication device does not receive an OD-SIB1 request ACK in the monitoring window. In yet another example, the communication device determines that the stored WUS configuration is invalid, based on the fact that the communication device does not receive an OD-SIB1 request ACK in the monitoring window. In yet another example, the communication device determines the stored WUS configuration (e.g., release) based on the fact that the communication device does not receive an OD-SIB1 request ACK in the monitoring window.

[0058] In one example, the communication device, depending on whether the stored WUS configuration is invalid, re-selects a different target cell according to the cell selection procedure.

[0059] In one example, a WUS configuration set further includes multiple thresholds (e.g., ReEst-preambleTransMax) corresponding to multiple WUS configurations (e.g., each of them). In one example, each of the thresholds indicates the maximum number of retries for a connected mode communication device to perform the OD-SIB1 procedure according to the corresponding WUS configuration. In one example, the communication device determines that the target cell is a cell that the communication device can camp on to, depending on whether the number of retries exceeds the corresponding threshold among the thresholds. In one example, the communication device determines (e.g., release) the WUS configuration set depending on whether the number of retries exceeds the corresponding threshold among the thresholds.

[0060] In one example, the communication device determines the WUS configuration set (for example, release it) in response to the start of the re-establishment procedure.

[0061] Figure 4 is a flowchart of process 40 according to an example of the present disclosure. Process 40 may be used in a serving cell (or serving BS) (for example, a cell in network 12 in Figure 1, a communication device 20 in Figure 2, or a serving cell in the example of process 30) to handle a re-establishment procedure. Process 40 may be compiled into program code 214, which includes the following steps:

[0062] Step 400: Start.

[0063] Step 402: Send a WUS configuration set to the communication device, which includes multiple IDs for multiple cells, multiple frequencies corresponding to multiple cells, and multiple WUS configurations corresponding to multiple cells.

[0064] Step 404: Finish.

[0065] According to process 40, the serving cell sends a WUS configuration set to a communication device (for example, the communication device of process 30). The WUS configuration set includes multiple IDs for multiple cells, multiple frequencies corresponding to (for example, each of) multiple cells, and multiple WUS configurations corresponding to (for example, each of) multiple cells.

[0066] The implementation of process 40 is not limited to the above description. The following examples may be applied to implement process 40.

[0067] In one example, multiple cells include a serving cell. In another example, multiple cells include at least one adjacent cell to the serving cell.

[0068] In one example, the WUS configuration set is transmitted via SIB. In one example, the WUS configuration set further includes multiple instructions corresponding to multiple WUS configurations (for example, each of them). In one example, each of the instructions indicates whether the corresponding WUS configuration is supported by a connected mode communication device.

[0069] In one example, a serving cell sends a cell list to a communication device. In another example, the cell list indicates which WUS configurations in the WUS configuration set are supported by the communication device in connected mode.

[0070] In one example, a WUS configuration set further includes multiple thresholds, each corresponding to a multiple WUS configuration. In one example, each of the multiple thresholds indicates the maximum number of retries for a connected mode communication device to perform the OD-SIB1 procedure according to the corresponding WUS configuration.

[0071] An example of process 30 may be applied to process 40, which will not be described herein for the sake of brevity.

[0072] Figure 5 is a flowchart of process 50 according to an example of the present disclosure. Process 50 may be used in an NES cell (or NES BS) (for example, the NES cell of network 12 in Figure 1, the communication device 20 in Figure 2, or the target cell of process 30) to handle a re-establishment procedure. Process 50 may be compiled into program code 214, which includes the following steps:

[0073] Step 500: Start.

[0074] Step 502: When at least one OD-SIB1 procedure trigger condition is met, perform an OD-SIB1 procedure with the communication device according to the stored WUS configuration.

[0075] Step 504: The NES cell receives a re-establishment request message from the communication device, depending on whether the communication device is a camp-on cell.

[0076] Step 506: Finish.

[0077] According to process 50, the NES cell performs an OD-SIB1 procedure with a communication device (e.g., the communication device of process 30) according to the stored WUS configuration, depending on whether at least one OD-SIB1 procedure trigger condition (e.g., all OD-SIB1 procedure trigger conditions) is met. Step 502 includes receiving an OD-SIB1 request from the communication device in the UL resource.

[0078] The implementation of process 50 is not limited to the above description. The following examples may be applied to implement process 50.

[0079] In one example, the cell on which the communication device can camp on is the highest-ranked cell based on measurements. In another example, the stored WUS configuration is included in the WUS configuration set. In yet another example, the WUS configuration set is sent by the serving cell device to the communication device and stored in the communication device.

[0080] In one example, at least one OD-SIB1 procedure trigger condition includes at least one of the following conditions: namely, the NES cell does not provide SIB1 (e.g., periodically), and the stored WUS configuration is valid. In one example, SIB1 includes at least one of the following information: namely, PLMN information, other SIB availability and scheduling, and access control information. In one example, PLMN information is used by the NES cell to determine whether the cell is one on which a communication device can be camped. In one example, the NES cell provides OD-SIB1 on demand (i.e., does not provide OD-SIB1 periodically). In one example, at least one OD-SIB1 procedure trigger condition includes the following condition: namely, the NES cell supports the OD-SIB1 procedure.

[0081] In one example, the stored WUS configuration is valid (or determined to be valid) depending on whether the current wireless frame's SFN is within a specific period (e.g., WUS_ValidPeriod). In another example, the stored WUS configuration is invalid (or determined to be invalid) at the end of a specific period. In yet another example, the stored WUS configuration is invalid (or determined to be invalid) depending on whether the current wireless frame's SFN is outside a specific period. In yet another example, the stored WUS configuration is invalid (or determined to be invalid) depending on whether the communication device initiates a re-establishment procedure.

[0082] In one example, the end of a particular period lies at the boundary of a correction period in which the communication device receives a configured SI change instruction from the serving cell of the communication device. That is, the particular period is terminated at the boundary of the correction period in accordance with the configured received SI change instruction. In another example, the end of a particular period lies at the boundary of the next correction period in which the communication device receives an unconfigured SI change instruction from the serving cell. That is, the particular period is terminated at the boundary of the next correction period in accordance with the unconfigured received SI change instruction.

[0083] In one example, the OD-SIB1 procedure includes at least one of the following steps: receiving an OD-SIB1 request (e.g., a preamble) from a communication device, and sending an OD-SIB1 request ACK (e.g., a RAR) to the communication device in response to the OD-SIB1 request. In one example, the NES cell sends a re-establishment message (e.g., Msg4) to the communication device in response to a re-establishment request message. In one example, the NES cell sends a setup message (e.g., Msg4) to the communication device in response to a re-establishment request message. In one example, the NES cell broadcasts OD-SIB1 to reduce signal overhead.

[0084] In one example, the UL resource is a Random Access (RA) resource. In one example, the OD-SIB1 request is used to inform the NES cell that the OD-SIB1 procedure is being triggered. In one example, the OD-SIB1 request ACK is used to inform the communication device that the OD-SIB1 request has been received by the target cell. In one example, the OD-SIB1 request ACK includes at least one of the following data: a Timing Advance (TA) value, a resource for the re-establishment request message, the identity of the communication device, and information about SIB1. In one example, the TA value is used for UL synchronization. In one example, the identity of the communication device includes a Random Access Preamble Identity (RAPID) or UE Temperate ID.

[0085] In one example, the OD-SIB1 request ACK contains the OD-SIB1. That is, to reduce the delay caused by the execution of the OD-SIB1 procedure, the NES cell does not need to send an additional OD-SIB1 to the communication device. In one example, the OD-SIB1 in the OD-SIB1 request ACK is a complete OD-SIB1. In one example, the complete OD-SIB1 contains target cell information (e.g., PLMN information) and at least one of SIB availability information, SIB scheduling information, and access control information. The target cell information is used by the communication device to determine whether the target cell is a cell that the communication device can camp on to. In one example, the OD-SIB1 in the OD-SIB1 request ACK is a simplified OD-SIB1. In one example, the simplified OD-SIB1 contains target cell information (e.g., only).

[0086] In one example, a UL resource for receiving a re-establishment request message is allocated by the OD-SIB1 request ACK. In this example, the UL resource allocated by the OD-SIB1 request ACK follows the DL resource for sending (e.g., broadcasting) the OD-SIB1.

[0087] Examples of processes 30-40 may be applied to process 50 and are not described herein for the sake of brevity.

[0088] Figure 6 is a sequence diagram of process 60 according to an example of the present disclosure. Figure 6 includes a communication device CM, a serving cell SC of the communication device CM, and a target cell TC of the communication device CM. The communication device CM is in idle or inactive mode. In step 600, the serving cell SC transmits its WUS configuration set to the communication device CM. In step 602, the communication device CM selects the target cell TC according to a cell selection procedure. The target cell TC is the highest-ranked cell based on measurements. In step 604, the communication device CM triggers the OD-SIB1 procedure according to a stored WUS configuration when at least one OD-SIB1 procedure trigger condition is met. The stored WUS configuration is contained in a WUS configuration set and corresponds to the target cell TC. The at least one OD-SIB1 procedure trigger condition includes at least one of the following: the target cell TC does not provide SIB1, the target cell TC is an NES cell, the stored WUS configuration is valid, and the target cell TC supports the OD-SIB1 procedure.

[0089] In step 606, the communication device CM selects a preamble as an OD-SIB1 request from the preamble pool. In step 608, the communication device CM sends an OD-SIB1 request to the target cell TC. In step 610, the communication device CM starts a monitoring window and monitors for OD-SIB1 request ACKs during the monitoring window. In step 612, the target cell TC sends an OD-SIB1 request ACK to the communication device CM. In step 614, the communication device CM stops the monitoring window. In step 616, the target cell TC sends an OD-SIB1 to the communication device CM. In step 618, the communication device CM determines, according to the OD-SIB1, whether the target cell TC is a cell that the communication device CM can camp on to. In step 620, if the target cell TC determines that the communication device CM is a cell that the communication device CM can camp on to, the communication device CM sends a re-establishment request message to the target cell TC and camps on to the target cell TC. In step 622, after the communication device CM has camped on to the target cell TC, the target cell TC sends its WUS configuration set to the communication device CM.

[0090] Figure 7 is a sequence diagram of process 70 according to an example of the present disclosure. Figure 7 includes a communication device CM, a serving cell SC of the communication device CM, and a target cell TC of the communication device CM. The communication device CM is in connection mode. In step 700, the serving cell SC transmits its WUS configuration set to the communication device CM. In step 702, the communication device CM detects a problem with the radio link and starts a first timer. In step 704, the communication device CM declares an RLF in response to the expiration of the first timer. In step 706, the communication device CM initiates a re-establishment procedure. In step 708, the communication device CM selects the target cell TC according to the cell selection procedure. In step 710, the communication device CM triggers an OD-SIB1 procedure according to a stored WUS configuration when at least one OD-SIB1 procedure trigger condition is met. The stored WUS configuration is included in the WUS configuration set and corresponds to the target cell TC. At least one OD-SIB1 procedure trigger condition includes at least one of the following: the target cell TC does not provide SIB1; the target cell TC is an NES cell; the stored WUS configuration is valid; and the target cell TC supports the OD-SIB1 procedure.

[0091] In step 712, the communication device CM selects a preamble from the preamble pool as an OD-SIB1 request. In step 714, the communication device CM sends an OD-SIB1 request to the target cell TC. In step 716, the communication device CM starts a monitoring window and monitors for OD-SIB1 request ACKs during the monitoring window. In step 718, the target cell TC sends an OD-SIB1 request ACK to the communication device CM within the monitoring window. In step 720, the communication device CM stops the monitoring window. In step 722, the target cell TC sends an OD-SIB1 to the communication device CM. In step 724, the communication device CM determines, based on the OD-SIB1, whether the target cell TC is a cell that can be camped on. In step 726, depending on whether the communication device CM is a cell that can be camped on, the communication device CM sends a re-establishment request message to the target cell TC. In step 728, the target cell TC sends a re-establishment message to the communication device CM in response to the re-establishment request message. In step 730, the communication device CM camps on to the target cell TC in accordance with the re-establishment message.

[0092] In steps 728 and 730, the re-establishment message may be replaced by the setup message.

[0093] Figure 8 is a sequence diagram of process 80 according to an example of the present disclosure. Figure 8 includes a communication device CM, a serving cell SC of the communication device CM, and a target cell TC of the communication device CM. The communication device CM is in connection mode. In step 800, the serving cell SC transmits its WUS configuration set to the communication device CM. In step 802, the communication device CM detects a problem with the radio link and starts a first timer. In step 804, the communication device CM declares an RLF in response to the expiration of the first timer. In step 806, the communication device CM initiates a re-establishment procedure. In step 808, the communication device CM selects the target cell TC according to the cell selection procedure. In step 810, the communication device CM triggers an OD-SIB1 procedure according to a stored WUS configuration when at least one OD-SIB1 procedure trigger condition is met. The stored WUS configuration is contained in the WUS configuration set and corresponds to the target cell TC. At least one OD-SIB1 procedure trigger condition includes at least one of the following: the target cell TC does not provide SIB1, the target cell TC is an NES cell, the stored WUS configuration is valid, and the target cell TC supports the OD-SIB1 procedure, and the target cell TC supports the OD-SIB1 procedure.

[0094] In step 812, the communication device CM selects a preamble from the preamble pool as an OD-SIB1 request. In step 814, the communication device CM sends an OD-SIB1 request to the target cell TC. In step 816, the communication device CM starts a monitoring window and monitors for OD-SIB1 request ACKs during the monitoring window. In step 818, the target cell TC sends an OD-SIB1 request ACK to the communication device CM within the monitoring window. The OD-SIB1 request ACK includes an OD-SIB1. In step 820, the communication device CM stops the monitoring window. In step 822, the communication device CM determines, according to the OD-SIB1, whether the target cell TC is a cell that can be camped on. In step 824, depending on whether the communication device CM is a cell that can be camped on, the target cell TC sends a re-establishment request message to the target cell TC. In step 826, the target cell TC sends a re-establishment message to the communication device CM in response to the re-establishment request message. In step 828, the communication device CM camps on to the target cell TC in accordance with the re-establishment message.

[0095] In steps 826 and 828, the re-establishment message may be replaced by the setup message.

[0096] Figure 9 is a flowchart of process 90 according to an example of the present disclosure. Process 90 may be used in a communication device (for example, communication device 14 in Figure 1, communication device 20 in Figure 2, or the communication device of process 30) to handle a re-establishment procedure. Process 90 may be compiled into program code 214, which includes the following steps:

[0097] Step 900: Start.

[0098] Step 902: Initiate the re-establishment procedure.

[0099] Step 904: Release the WUS configuration set received from the serving cell.

[0100] Step 906: Follow the cell selection procedure to select the target cell.

[0101] Step 908: Does the target cell provide an SIB? If so, perform step 910. Otherwise, perform step 906.

[0102] Step 910: Is the target cell a cell on which a communication device can be camped? If so, perform step 912. If not, perform step 906.

[0103] Step 912: Send a re-establishment request message to the target cell.

[0104] Step 914: Finish.

[0105] Figure 10 is a flowchart of process 100 according to an example of the present disclosure. Process 100 may be used in a communication device (for example, communication device 14 in Figure 1, communication device 20 in Figure 2, or the communication device of process 30) to handle a re-establishment procedure. Process 100 may be compiled into program code 214, which includes the following steps:

[0106] Step 1000: Start.

[0107] Step 1002: Receive a WUS configuration set from the serving cell, which includes multiple WUS configurations and multiple instructions corresponding to the multiple WUS configurations.

[0108] Step 1004: Start the re-establishment procedure.

[0109] Step 1006: Follow the instructions to select the target cell in the cell selection procedure.

[0110] Step 1008: Trigger an OD-SIB1 procedure on the target cell according to the stored WUS configuration, depending on whether at least one OD-SIB1 procedure trigger condition is met.

[0111] Step 1010: Based on the SIB1 from the target cell, the target cell determines whether or not it is a cell on which a communication device can be camped.

[0112] Step 1012: Depending on whether the target cell is a cell that can camp on the communication device, the target cell sends a re-establishment request message to the target cell.

[0113] Step 1014: Finish.

[0114] In step 1002, each of the multiple instructions indicates whether the corresponding WUS configuration is supported by the communication device in connected mode. In step 1004, the communication device does not select a cell that does not support the OD-SIB1 procedure. In step 1006, at least one OD-SIB1 procedure trigger condition includes at least one of the following conditions: the target cell does not provide SIB1, the target cell is an NES cell, and the target cell supports the OD-SIB1 procedure.

[0115] Detailed descriptions and variations of processes 90-100 can be left to the example of process 30 and are not described herein.

[0116] Figure 11 is a sequence diagram of process 110 according to an example of the present disclosure. Figure 11 includes a communication device CM, a serving cell SC of the communication device CM, and a target cell TC of the communication device CM. In step 1100, the serving cell SC sends its WUS configuration set to the communication device CM. In step 1102, the communication device CM selects the target cell TC according to the cell selection procedure. In step 1104, the communication device CM triggers the OD-SIB1 procedure according to the stored WUS configuration when at least one OD-SIB1 procedure trigger condition is met. The stored WUS configuration is contained in the WUS configuration set and corresponds to the target cell TC. The at least one OD-SIB1 procedure trigger condition includes at least one of the following: the target cell TC does not provide an SIB1, the target cell TC is an NES cell, and the target cell TC supports the OD-SIB1 procedure. In step 1106, the communication device CM selects a preamble from the preamble pool as an OD-SIB1 request. In step 1108, the communication device CM sends an OD-SIB1 request to the target cell TC. In step 1110, the communication device CM starts a monitoring window and monitors for the OD-SIB1 request ACK during the monitoring window. In step 1112, if the communication device CM does not receive the OD-SIB1 request ACK during the monitoring window, the communication device CM releases the stored WUS configuration, and the target cell TC determines that the communication device CM is not a cell that can be camped on.

[0117] Figure 12 is a schematic diagram of a specific period SP for verifying whether a stored WUS configuration is valid, according to an example of the present disclosure. Figure 12 has a time-domain axis T, on which there are two correction periods MP1-MP2 and three boundary MPB1-MPB3 of the correction periods. Boundary MPB1 is the beginning of correction period MP1. Boundary MPB2 is the end of correction period MP1 and the beginning of correction period MP2. Boundary MPB3 is the end of correction period MP2. The arrow in correction period MP1 represents the moment when the communication device receives an SI change instruction from the serving cell. This moment is the beginning of a specific period SP. Since no SI change instruction has been set, the communication device ends the specific period SP at boundary MPB3. Therefore, the communication device determines that the stored WUS configuration is valid, depending on whether the SFN of the current radio frame is within the specific period SP. At the end of the specific period, the communication device determines that the stored WUS configuration is invalid.

[0118] Figure 13 is a schematic diagram of a specific period SP for verifying whether a stored WUS configuration is valid, according to an example of the present disclosure. Figure 13 has a time-domain axis T, on which there are two correction periods MP1 and MP2 and three boundaries MPB1 to MPB3 of the correction periods. Boundary MPB1 is the beginning of correction period MP1. Boundary MPB2 is the end of correction period MP1 and the beginning of correction period MP2. Boundary MPB3 is the end of correction period MP2. The arrow in correction period MP1 represents the moment when the communication device receives an SI change instruction from the serving cell. This moment is the beginning of a specific period SP. Since an SI change instruction has been set, the communication device ends the specific period SP at boundary MPB2. Therefore, the communication device determines that the stored WUS configuration is valid, depending on whether the SFN of the current radio frame is within the specific period SP. The communication device determines that the stored WUS configuration is invalid at the end of the specific period.

[0119] The terms “first,” “second,” “third,” and “fourth” above are used to distinguish related discourses and do not limit the order of related discourses. The action of “determine” above may be replaced by the actions of “compute,” “calculate,” “obtain,” “generate,” “output,” “use,” “choose / select,” “determine,” or “is configured to.” The phrase “according to” above may be replaced by “in response to.” The term “via” above may be replaced by “on,” “in,” or “at.” The terms “when,” “if,” and “since” above may be replaced by “in response to.” The term “WUS configuration” above may be replaced by the term “random access (RA) procedure configuration.”

[0120] Those skilled in the art should be able to easily combine, modify, and / or alter the above description and examples. Processes comprising the above description, steps, and / or suggested steps may be implemented by means that may be hardware, software, firmware (known as a combination of a hardware device and computer instructions and data existing as read-only software on the hardware device), electronic systems, or combinations thereof. An example of such means may be a communication device.

[0121] Examples of hardware may include analog circuits, digital circuits, and / or mixed circuits. For example, hardware may include ASICs, field-programmable gate arrays (FPGAs), programmable logic devices, coupled hardware components, or combinations thereof. In other examples, hardware may include general-purpose processors, microprocessors, controllers, digital signal processors (DSPs), or combinations thereof.

[0122] Examples of software may include a set of code, instructions, and / or functions held (e.g., stored) in a storage unit, such as a computer-readable medium. The computer-readable medium may include a SIM, ROM, flash memory, RAM, CD-ROM / DVD-ROM / BD-ROM, magnetic tape, hard disk, optical data storage device, non-volatile storage unit, or a combination thereof. The computer-readable medium (e.g., storage unit) may be internally coupled (e.g., integrated) or externally coupled (e.g., isolated) to at least one processor. At least one processor, which may include one or more modules, may execute (e.g., be configured to execute) the software in the computer-readable medium. The set of code, instructions, and / or functions may cause at least one processor, module, hardware, and / or electronic system to perform the relevant steps.

[0123] Examples of electronic systems may include system-on-a-chip (SoC), system-in-package (SiP), computer-on-module (CoM), computer program products, devices, mobile phones, laptops, tablet computers, e-books, or portable computer systems, and communication devices20.

[0124] In summary, embodiments of the present disclosure provide a method and a communication device for handling a re-establishment procedure. The communication device verifies whether a stored WUS configuration corresponding to a target cell is valid. If the stored WUS configuration is valid, the communication device performs the OD-SIB1 procedure according to the stored WUS configuration. If the stored WUS configuration is invalid, the communication device re-selects a different target cell. Thus, the problem of handling a re-establishment procedure can be solved.

[0125] The above outlines some features of embodiments that will enable those skilled in the art to fully understand aspects of the present disclosure. Those skilled in the art will recognize that the present disclosure provides a basis for designing or modifying other processes and structures to achieve substantially the same functions and / or substantially the same results as the embodiments described herein. Furthermore, such equivalent arrangements may be made in various ways, substitutions, and modifications, without departing from the spirit and scope of the present disclosure. [Explanation of Symbols]

[0126] 10 Wireless communication systems 12 Networks 14 Communication devices 20 Communication devices 200 At least one processing circuit 210 At least one storage device 214 Program Code 220 At least one communication interface device

Claims

1. A method for a communication device to process a re-establishment procedure, The steps include: initiating the aforementioned re-establishment procedure, The steps involve selecting the target cell according to the cell selection procedure, The steps include triggering an OD-SIB1 procedure on the target cell according to a stored wake-up signal (WUS) configuration when at least one on-demand system information block 1 (OD-SIB1) procedure trigger condition is met, The steps include selecting an OD-SIB1 request from the preamble pool, The OD-SIB1 procedure includes the step of sending the OD-SIB1 request to the target cell in the uplink (UL) resource, The steps include determining whether the target cell is a cell on which the communication device can camp, based on the SIB1 from the target cell, The target cell, depending on whether the communication device is a cell that can be camped on, sends a re-establishment request message to the target cell. Methods that include...

2. The above-mentioned at least one OD-SIB1 procedure trigger condition is the following condition, namely: The target cell does not provide the SIB1. The target cell is a network energy saving (NES) cell, and The stored WUS configuration is valid. The method according to claim 1, comprising at least one of the following.

3. The method according to claim 1, further comprising the step of verifying whether the stored WUS configuration is valid.

4. The step of verifying whether the stored WUS configuration is valid is: The steps include determining whether the stored WUS configuration is valid based on whether the system frame number (SFN) of the current wireless frame falls within a specific period, The steps include determining at the end of the aforementioned specific period that the stored WUS configuration is invalid, and The method according to claim 3, comprising at least one of the following.

5. The method according to claim 4, further comprising the step of determining the end of the particular period.

6. The step of determining the end of the aforementioned specific period is: The steps include receiving a system information (SI) change instruction from the serving cell of the communication device during the correction period, The step of ending the specific period at the boundary of the aforementioned correction period. The method according to claim 5, including the method described in claim 5.

7. The OD-SIB1 procedure described above is Starting the monitoring window, In the aforementioned monitoring window, the OD-SIB1 request acknowledgment (ACK) is monitored, The monitoring window is stopped in response to the receipt of the OD-SIB1 request ACK from the target cell. The method according to claim 1, comprising at least one of the following.

8. In the aforementioned monitoring window, monitoring the OD-SIB1 request ACK is performed. The method according to claim 7, comprising determining the stored WUS configuration in accordance with the expiration of the monitoring window.

9. In the aforementioned monitoring window, monitoring the OD-SIB1 request ACK is performed. Upon the expiration of the aforementioned monitoring window, the OD-SIB1 request is resent to the target cell. In response to the retransmission of the OD-SIB1 request to the target cell, the value of the counter is incremented by 1. In accordance with the fact that the value of the counter is greater than the threshold, it is determined that the target cell is a prohibited cell. The method according to claim 7, comprising at least one of the following.

10. The aforementioned OD-SIB1 request ACK contains the following data, namely: Timing Advance (TA) value, Resources for the aforementioned re-establishment request message, The identity of the aforementioned communication device, and Information relating to the aforementioned SIB1 The method according to claim 7, comprising at least one of the following.

11. The OD-SIB1 procedure described above is The method of claim 7, further comprising monitoring the SIB1 in response to monitoring the OD-SIB1 request ACK.

12. A serving cell method for handling a re-establishment procedure, The process includes the step of sending a Wake-Up Signal (WUS) configuration set to a communication device, The WUS configuration set includes multiple identities (IDs) of multiple cells, multiple frequencies corresponding to the multiple cells, and multiple WUS configurations corresponding to the multiple cells. A method wherein the plurality of cells include the serving cell.

13. The method according to claim 12, wherein the WUS configuration set further includes a plurality of instructions corresponding to the plurality of WUS configurations.

14. The method according to claim 13, wherein each of the plurality of instructions indicates whether the corresponding WUS configuration is supported by the communication device in connection mode.

15. The further step includes sending a cell list to the aforementioned communication device, The method according to claim 12, wherein the cell list indicates which WUS configurations of the WUS configuration set are supported by the communication device in connection mode.

16. The method according to claim 12, wherein the WUS configuration set further includes a plurality of thresholds corresponding to the plurality of WUS configurations.

17. The method according to claim 16, wherein each of the plurality of thresholds indicates the maximum number of retries for the communication device in connection mode to perform the on-demand system information block 1 (OD-SIB1) procedure according to the corresponding WUS configuration.

18. A method for handling a re-establishment procedure for a network energy saving (NES) cell, The steps include: performing an OD-SIB1 procedure with a communication device according to a stored wake-up signal (WUS) configuration in response to the fulfillment of at least one On-Demand System Information Block 1 (OD-SIB1) procedure trigger condition; Depending on whether the NES cell is a cell capable of camping on the communication device, the NES cell receives a re-establishment request message from the communication device. Includes, The step of performing the OD-SIB1 procedure is, A method comprising the step of receiving an OD-SIB1 request from a communication device in an uplink (UL) resource.

19. The above-mentioned at least one OD-SIB1 procedure trigger condition is the following condition, namely: The NES cell does not provide SIB1, and The stored WUS configuration is valid. The method according to claim 18, comprising at least one of the following.

20. The method according to claim 18, wherein the stored WUS configuration is valid depending on whether the system frame number (SFN) of the current wireless frame is within a specific period.

21. The method according to claim 18, wherein the stored WUS configuration is invalid at the end of the specified period.

22. The method according to claim 21, wherein the end of the specific period falls on the boundary of a correction period in which the communication device receives a system information (SI) change instruction set from the serving cell of the communication device.

23. The OD-SIB1 procedure described above is The method according to claim 18, comprising sending an OD-SIB1 request acknowledgment (ACK) to the communication device in response to the OD-SIB1 request.

24. The aforementioned OD-SIB1 request ACK contains the following data, namely: Timing Advance (TA) value, Resources for the aforementioned re-establishment request message, The identity of the aforementioned communication device, and Information regarding SIB1 The method according to claim 23, comprising at least one of the following.

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