Communication method, device and system and storage medium

Abstract

The invention provides a communication method, device and system and a storage medium, and relates to the technical field of communication. The communication method of the present disclosure comprises: a base station establishing a radio resource control (RRC) connection with a first user equipment (UE), where an RRC establishment completion message carries store-and-forward capability indication information; the base station sends a first RRC release message to the first UE under the condition of determining that the feeder link with the core network is not activated; in response to activation of the feeder link, the base station sends registration information of the first UE to a core network; and the base station receives the paging message from the core network, and initiates paging to the first UE according to the paging message so as to recover the RRC connection with the first UE under the condition that the base station moves to cover the position area where the first UE is located.

Description

Technical Field

[0001] This disclosure relates to the field of communication technology, and in particular to a communication method, apparatus, system and storage medium. Background Technology

[0002] The standard definition of NTN (Non-Terrestrial Network) given by 3GPP is "a network or network segment that uses airborne or space-based vehicles to carry transmission equipment, relay nodes or base stations." Simply put, it includes any network that involves non-ground flying objects.

[0003] Current 3GPP NTN research defines two typical transmission architectures: transparent forwarding, where signals undergo only frequency conversion and signal amplification on the satellite, with base stations (gNB / eNB) located on the ground; and regenerative transmission (on-board access / processing), where the satellite possesses some or all of the base station functions. It is anticipated that all NGSO constellations to be deployed within the next 10 years will be designed to support inter-satellite links and carry regenerative payloads.

[0004] Once an IoT constellation system is built and put into commercial operation, if the inter-satellite links become unavailable, there may be situations where operational satellites and ground gateways lack real-time communication links. Furthermore, due to operational cost considerations, the satellite constellation may only support discontinuous coverage, which will disrupt some services, impact user experience, and hinder the operator's continued smooth operation. Summary of the Invention

[0005] One objective of this disclosure is to propose a scheme for implementing store-and-forward mode in NTN communication, thereby improving communication reliability.

[0006] According to one aspect of some embodiments of this disclosure, a communication method is proposed, comprising: a base station establishing an RRC (Radio Resource Control) connection with a first UE (User Equipment), wherein the RRC establishment completion message carries store-and-forward capability indication information; if it is determined that the feeder link with the core network is not activated, the base station sends a first RRC release message to the first UE; in response to activating the feeder link, the base station sends registration information of the first UE to the core network; the base station receives a paging message from the core network, and if it moves to a location area covering the first UE, it initiates paging to the first UE according to the paging message in order to restore the RRC connection with the first UE.

[0007] In some embodiments, the method further includes: the base station sending store-and-forward mode operating status information via a broadcast message, wherein the first UE sends an RRC establishment request to the base station according to the store-and-forward mode operating status information, and the base station establishes an RRC connection with the first UE according to the RRC establishment request.

[0008] In some embodiments, the broadcast message may also include a satellite identifier.

[0009] In some embodiments, the first RRC release message includes first release reason information, which indicates that the RRC connection needs to be paused due to a store-and-forward operation.

[0010] In some embodiments, the first RRC release message also includes timer information, which indicates the time for pausing the user equipment's request to establish an RRC connection with a base station in the same PLMN in store-forward mode.

[0011] In some embodiments, the method further includes: the base station establishing an RRC connection with the second UE, wherein the second UE does not have store-and-forward capability; and the base station sending a second RRC release message to the second UE when it determines that the feeder link between the base station and the core network is not activated, wherein the second RRC release message includes second release reason information, which is different from the first release reason information.

[0012] In some embodiments, the method further includes: after the base station sends the registration information of the first UE to the core network, it obtains indication information indicating that the data of the first UE is cached in the base station, wherein the core network initiates the initial context establishment of the UE based on the registration information and sends the indication information.

[0013] In some embodiments, the method further includes: the base station initiating a first UE context suspension procedure to the core network to store the context of the first UE in the base station, wherein the first UE context suspension procedure is used to suspend the logical interface connection associated with the first UE and the user plane transmission bearer with the core network.

[0014] In some embodiments, the method further includes: during the first UE context pause procedure, the base station sends the location information of the first UE to the core network, the location information including at least one of cell identifier or tracking area identifier.

[0015] In some embodiments, the method further includes: after establishing an RRC connection with the first UE according to an RRC establishment request from the first UE, the base station acquires and stores uplink data of the first UE; and after completing the initial UE context establishment with the core network, the base station sends the uplink data to the core network.

[0016] In some embodiments, the method further includes: receiving and storing downlink data from the core network after completing the initial UE context establishment with the core network; and sending the downlink data to the first UE after restoring the RRC connection with the first UE.

[0017] In some embodiments, the method further includes: after the base station restores the RRC connection with the first UE, receiving uplink data from the first UE; and if the base station determines that the feeder link with the core network is not activated, storing the uplink data so as to send it to the core network after the feeder link is activated.

[0018] In some embodiments, the method further includes: in response to activating the feeder link, the base station initiates context recovery to the core network for the first UE; the base station receives a paging message from the core network, and, if it moves to a location area covering the first UE, initiates paging to the first UE according to the paging message in order to restore the RRC connection with the first UE.

[0019] In some embodiments, the method further includes: after the base station restores the RRC connection with the first UE, performing at least one of the following: receiving and storing uplink data of the first UE until the feeder link becomes available again and forwarding the data to the core network; or sending cached downlink data from the core network to the first UE.

[0020] According to one aspect of some embodiments of this disclosure, a communication method is proposed, comprising: a user equipment (UE) establishing an RRC connection with a base station operating in store-and-forward mode, and carrying store-and-forward capability indication information in an RRC establishment completion message; releasing the RRC connection with the base station in response to a first RRC release message from the base station, wherein the base station sends the first RRC release message to a first UE when it determines that the feeder link with the core network is not activated; and restoring the RRC connection with the base station in response to receiving a paging message from the base station.

[0021] In some embodiments, the method further includes: receiving a broadcast message from a base station; and sending an RRC establishment request to the base station based on store-and-forward mode operating status indication information carried in the broadcast message.

[0022] In some embodiments, the method further includes: after establishing an RRC connection with the base station according to the store-and-forward mode working status indication information carried in the broadcast message, sending uplink data to the base station, wherein the base station stores the uplink data and sends the uplink data to the core network after completing the initial UE context establishment with the core network.

[0023] In some embodiments, the method further includes: receiving downlink data from the base station after restoring the RRC connection with the base station, wherein the base station receives and stores the downlink data from the core network after completing the initial UE context establishment with the core network.

[0024] In some embodiments, the method further includes: sending uplink data to the base station after restoring the RRC connection with the base station, wherein the base station stores the uplink data in case it determines that the feeder link with the core network is not activated, so as to send it to the core network after activating the feeder link.

[0025] In some embodiments, the method further includes: after restoring the RRC connection with the base station, performing at least one of the following: sending uplink data to the base station, wherein the base station receives and stores the uplink data of the first UE until the feeder link is available again and forwards the data to the core network; or receiving downlink data from the core network cached by the base station.

[0026] According to one aspect of some embodiments of this disclosure, a communication apparatus is provided, comprising: a first RRC connection establishment unit configured to establish an RRC connection with a first UE, wherein the RRC establishment completion message carries store-and-forward capability indication information; a first RRC connection release unit configured to send a first RRC release message to the first UE when it is determined that the feeder link with the core network is not activated; a registration unit configured to send registration information of the first UE to the core network in response to activating the feeder link; and a first RRC connection restoration unit configured to receive a paging message from the core network and, when moving to a location area covering the location of the first UE, initiate paging to the first UE according to the paging message in order to restore the RRC connection with the first UE.

[0027] In some embodiments, the apparatus further includes: a broadcast unit configured to send store-and-forward mode operating status information via a broadcast message, wherein a first UE sends an RRC establishment request to a base station based on the store-and-forward mode operating status information, and the base station establishes an RRC connection with the first UE based on the RRC establishment request.

[0028] In some embodiments, the apparatus further includes: a first data transmission unit configured to, after establishing an RRC connection with the first UE according to an RRC establishment request from the first UE, acquire and store uplink data of the first UE; and, upon completion of the initial UE context establishment with the core network, send the uplink data to the core network.

[0029] In some embodiments, the apparatus further includes: a context recovery unit configured to initiate context recovery of the first UE to the core network in response to activating the feeder link; the first RRC connection recovery unit is further configured to receive a paging message from the core network, and, if moved to a location area covering the first UE, to initiate paging of the first UE according to the paging message in order to restore the RRC connection with the first UE.

[0030] According to one aspect of some embodiments of this disclosure, a communication apparatus is provided, comprising: a second RRC connection unit configured to establish an RRC connection with a base station operating in store-and-forward mode, and carrying store-and-forward capability indication information in an RRC establishment completion message; a second RRC connection release unit configured to release the RRC connection with the base station in response to a first RRC release message from the base station, wherein the base station sends the first RRC release message to a first UE when it determines that the feeder link with the core network is not activated; and a second RRC connection restoration unit configured to restore the RRC connection with the base station in response to receiving a paging message from the base station.

[0031] In some embodiments, the apparatus further includes: a second data transmission unit configured to send uplink data to the base station after establishing an RRC connection with the base station according to the store-and-forward mode operating status indication information carried in the broadcast message, wherein the base station stores the uplink data and sends the uplink data to the core network after completing the initial UE context establishment with the core network.

[0032] According to one aspect of some embodiments of this disclosure, a communication device is provided, comprising: a memory; and a processor coupled to the memory, the processor being configured to execute any of the communication methods described above based on instructions stored in the memory.

[0033] According to one aspect of some embodiments of the present disclosure, a computer-readable storage medium is provided that stores computer program instructions that, when executed by a processor, implement any of the communication methods described above.

[0034] According to one aspect of some embodiments of this disclosure, a computer program product is proposed, including a computer program or instructions that, when executed by a processor, implement any of the communication methods described above.

[0035] According to one aspect of some embodiments of this disclosure, a communication system is proposed, comprising: a base station configured to perform any of the communication methods performed by the base station as described above; and a core network configured to receive registration information of a first UE from the base station and send a paging message to the base station.

[0036] In some embodiments, the system further includes a user equipment configured to perform any of the communication methods described above that are performed by the user equipment side. Attached Figure Description

[0037] The accompanying drawings, which are included to provide a further understanding of this disclosure and form part of this disclosure, illustrate exemplary embodiments of this disclosure and are used to explain this disclosure, but do not constitute an undue limitation of this disclosure.

[0038] Figure 1 These are schematic diagrams illustrating some embodiments of the communication method disclosed herein.

[0039] Figure 2 Flowcharts showing some embodiments of the communication method disclosed herein.

[0040] Figure 3 Flowcharts showing some other embodiments of the communication method disclosed herein.

[0041] Figure 4 This is a signaling flowchart for some embodiments of the communication method disclosed herein.

[0042] Figure 5 Signaling flowcharts for some other embodiments of the communication method disclosed herein.

[0043] Figure 6 These are schematic diagrams illustrating some embodiments of the communication apparatus disclosed herein.

[0044] Figure 7 These are schematic diagrams illustrating some embodiments of the communication apparatus disclosed herein.

[0045] Figure 8 These are schematic diagrams illustrating some embodiments of the communication apparatus disclosed herein.

[0046] Figure 9 These are schematic diagrams illustrating some embodiments of the communication apparatus disclosed herein.

[0047] Figure 10 These are schematic diagrams illustrating some embodiments of the communication system disclosed herein. Detailed Implementation

[0048] The technical solutions of this disclosure will be further described in detail below with reference to the accompanying drawings and embodiments.

[0049] Store and Forward (S&F) is an effective method for solving data transmission problems in remote areas, even when the satellite is not directly connected to a terrestrial network. Specifically, when a satellite passes over a remote area, it can receive data packets from user equipment. The satellite then stores these data packets in its own memory. When the satellite connects to a terrestrial network, it forwards the stored data packets to the terrestrial network.

[0050] The 3GPP Release 19 NTN project adds new scenarios for satellite communications, including IoT applications with discontinuous link store-and-forward. Supporting store-and-forward (S&F) satellite operation with regenerative payloads has the following advantages:

[0051] (1) S&F operation allows for the provision of latency-tolerant, non-real-time IoT NTN services in satellite-accessible areas, but does not require NTN gateway infrastructure (such as at sea or in remote areas);

[0052] (2) In addition to supporting discontinuous coverage, supporting S&F operation is the key to promoting low-cost deployment of IoT NTN services and enabling real-time operational services through sparse LEO constellations and reduced ground segment infrastructure.

[0053] (3) The S&F solution based on 3GPP NTN has advantages in cost and development prospects compared with other non-3GPP solutions for large-scale satellite IoT.

[0054] However, among related technologies, satellite store-and-forward mode communication methods are mainly aimed at non-3GPP systems. There is a lack of in-depth research on signaling interaction between users and network equipment and on uplink and downlink data transmission, resulting in weak operability.

[0055] To address the aforementioned issues, this disclosure proposes a communication method, apparatus, system, and storage medium to achieve mutual cooperation between base stations, user equipment, and the core network in S&F-based NTN communication, thereby improving communication reliability.

[0056] In some embodiments, the application scenarios of this disclosure are as follows: Figure 1As shown, it is assumed that the low-Earth orbit satellite is located at an altitude of less than 600 kilometers with an orbital period of approximately 90 minutes. The size of the satellite coverage area depends on various factors, but for simplicity, it is assumed that the satellite provides service to a given location on Earth each time it passes by, for example, for 5 minutes. Due to the Earth's rotation, the same satellite can only pass through the same geographical area after several orbits, as shown in the geographical areas where the satellite is located at times T1-T5, where the satellite passes through the same geographical area at times T1 and T5. If multiple satellites exist, the UE may interact with different satellites. Due to the non-continuous coverage characteristics of sparse constellations, the UE will receive service intermittently, for example, within 5-minute intervals over several hours.

[0057] The above-mentioned height and time settings are for illustrative purposes only and do not constitute an undue limitation on this disclosure.

[0058] Flowcharts of some embodiments of the communication method disclosed herein are as follows: Figure 2 As shown. Figure 2 In the illustrated embodiment, the communication method is performed by a base station. This base station is a base station built on non-terrestrial equipment, such as a satellite base station.

[0059] In step S21, the base station establishes an RRC connection with the first UE. In some embodiments, the base station and the first UE can establish an RRC connection based on the RRC connection establishment process in related technologies. The first UE is a UE with store-and-forward capability. In the RRC establishment completion message fed back to the base station, the first UE carries store-and-forward capability indication information so that the base station can determine that the first UE supports the store-and-forward function and take the operation associated with the store-and-forward mode for the first UE, triggering the execution of step S22.

[0060] In some embodiments, after establishing an RRC connection with the first UE, the base station can receive uplink data sent by the first UE. For example, if the first UE is an NB-IoT (Narrow Band Internet of Things) device, in scenarios such as emergency calls, the small uplink data packets are encapsulated in a NAS (Non-access stratum) PDU (Protocol Data Unit) and transmitted to the base station through control plane signaling messages to improve the timeliness of uplink data transmission.

[0061] In steps S22-S23, if it is determined that the feeder link between the base station and the core network is not activated, the base station sends a first RRC release message to the first UE, causing the connection to enter an idle state or an inactive state.

[0062] In some embodiments, after establishing an RRC connection and obtaining the RRC establishment completion message from the first UE, the base station may immediately initiate the release of the RRC connection, thereby reducing the equipment processing burden and reducing the continuous occupation of base station and UE resources.

[0063] In some embodiments, the base station may proactively release the RRC connection after a predetermined duration of RRC connection establishment, thereby reducing the unnecessary occupation of UE and base station resources while receiving uplink data.

[0064] In some embodiments, the first RRC release message may carry first release reason information. The release reason in related technologies can be extended by adding a reason value indicating that the RRC connection needs to be paused due to a store-and-forward operation, thereby facilitating the user equipment to know the release reason and also making it easier for the user to know the network status.

[0065] In some embodiments, the first RRC release message may also carry a timer to indicate to the first UE when it may retry the recovery process. During the duration of this timer value, the UE should not initiate connection attempts with any NTN cell operating in store-and-forward mode within the same PLMN. In some embodiments, the first UE can distinguish between devices carrying the current base station and other devices based on non-terrestrial device identifiers (such as satellite identifiers) obtained in the preceding process, thereby avoiding communication process confusion or data loss caused by initiating connections to other base stations and improving communication reliability.

[0066] In step S24, as the non-ground equipment carrying the base station moves, the base station establishes a connection with the ground core network, activates the feeder link, and triggers the execution of step S25. In some embodiments, if the feeder link cannot be activated, the base station continues to attempt and determine whether the feeder link can be activated.

[0067] In step S25, the base station sends the registration information of the first UE to the core network. In some embodiments, the base station sends the registration information of the first UE to the core network based on the information of the first UE obtained in step S21 above.

[0068] In some embodiments, the core network may initiate an initial UE context establishment process for the first UE based on the registration information of the first UE. In some embodiments, the established initial UE context includes PDU session context, security key, mobility restriction list, UE radio capabilities, and UE security capabilities. After the initial context of the first UE is established, step S26 is executed.

[0069] In some embodiments, if the base station obtains uplink data from the first UE after step S21, it can send the uplink data to the core network after the context is established. In some embodiments, the base station can also receive and cache downlink data from the core network.

[0070] In some embodiments, the base station may also initiate a context suspension procedure for the first UE to suspend the logical interface connection associated with the first UE and the username transmission bearer associated with the first UE and the core network, while keeping the first UE context in the base station. In some embodiments, the base station may send UE location information (e.g., mapped cell ID, TA, etc. bound to a geographical area) used for auxiliary information during paging to the core network during the context suspension procedure for the first UE.

[0071] In step S26, the base station receives a paging message for the first UE from the core network. The base station stores the paging message. As the non-ground equipment carrying the base station moves, step S27 is executed.

[0072] In step S27, it is determined whether the device has moved to an area that covers the location of the first UE. If the non-ground device moves to an area that the base station can cover the location of the first UE, the base station executes step S28. If the device has not yet moved to an area that the base station can cover the location of the first UE, the location is determined in real time as the device moves.

[0073] In step S28, a paging message is initiated to the first UE in order to restore the RRC connection with the first UE.

[0074] In some embodiments, if the base station receives downlink data from the core network in step S25 above, it can send it to the first UE after the RRC connection is restored, thereby realizing downlink data transmission from the terrestrial core network to the first UE. In some embodiments, the base station can also receive and buffer uplink data from the first UE after the RRC connection is restored, so as to send it to the terrestrial core network after the next restoration of the feeder link, thereby realizing uplink data transmission from the first UE to the terrestrial core network.

[0075] Based on the method in the embodiments shown above, the base station can adopt a store-and-forward working mode and release or suspend the RRC connection with the UE when the base station service link is available but a connection with the core network cannot be established; when the connection between the base station and the core network is available, a UE context is established and user data is exchanged; the UE context pause / resume procedure is used to support intermittent transmission characteristics, thereby providing a complete interaction process for signaling interaction and uplink / downlink data transmission between users and network devices in store-and-forward mode in NTN communication, effectively solving the problem of discontinuous coverage of NTN base stations and improving the reliability of communication.

[0076] In some embodiments, if a base station operating in store-and-forward mode establishes an RRC connection with a user equipment (hereinafter referred to as the second UE) that does not support store-and-forward, for example, if the RRC establishment completion message returned by the UE does not carry store-and-forward capability indication information, then the base station, upon determining that the feeder link with the core network is not activated, sends a second RRC release message to the second UE. The second RRC release message includes second release reason information, which differs from the first release reason information mentioned above, thereby helping the user equipment distinguish between RRC connection releases caused by store-and-forward mode and other RRC connection releases. In some embodiments, the second release reason information can be congestion or other (other is an open-ended reason identifier, meaning the information carried is specifically the identifier corresponding to "other").

[0077] In some embodiments, before step S21 described above, step S20 may be included: the base station sends store-and-forward mode operating status information via a broadcast message. When the first UE receives the broadcast message, it identifies the store-and-forward mode operating status information therein and then sends an RRC establishment request to the base station that sent the broadcast message. Further, the base station executes step S21 according to the RRC establishment request to establish an RRC connection with the first UE. Through this method, the base station can be discovered and identified by the UE via a broadcast message carrying the store-and-forward mode operating status, improving the timeliness of establishing an RRC connection with the UE.

[0078] In some embodiments, the broadcast message sent by the base station also includes a non-terrestrial device identifier (such as a satellite identifier). The UE can identify the non-terrestrial device where the base station that has established an RRC connection with it is located through the satellite identifier. In this way, when the RRC connection with the base station is subsequently restored, the UE can identify the non-terrestrial device, avoid establishing RRC connections with base stations mounted on multiple non-terrestrial devices, thereby avoiding data loss and improving the reliability of communication.

[0079] In some embodiments, after step S28, if the base station moves out of the area that can cover the location of the first UE, the service link is unavailable. When the base station moves again to a location where it can establish a connection with the ground core network and the feeder link is available, step S29 is executed.

[0080] In step S29, the base station initiates context recovery for the first UE to the core network. After context recovery, the base station can send cached uplink data to the ground core network, or receive and cache downlink data from the ground core network. Additionally, the base station receives paging messages from the core network. This method enables interaction between the first UE and the core network by restoring the previously established context, avoiding excessive signaling burden and reducing the risk of data loss.

[0081] In some embodiments, after step S29, when the base station moves again to cover the area where the first UE is located, it initiates a paging message to the first UE to restore the RRC connection with the first UE. In some embodiments, after restoring the RRC connection with the first UE, the base station may receive and store the uplink data of the first UE until the feeder link becomes available again and forwards the data to the core network. In some embodiments, the base station may send cached downlink data from the core network to the first UE.

[0082] This method enables interaction between the first UE and the core network by restoring previously established connections and contexts, avoiding excessive signaling burden, improving connection efficiency, and reducing the risk of data loss.

[0083] Flowcharts of other embodiments of the communication method disclosed herein are as follows: Figure 3 As shown. Figure 3 The communication method shown is performed by a user equipment (the first UE mentioned above), which has store-and-forward functionality. In some embodiments, the base station in the process is an NTN base station, mounted on non-terrestrial equipment, to perform the method in any of the embodiments performed by the base station described above.

[0084] In step S31, the UE establishes an RRC connection with the base station operating in store-and-forward mode and carries store-and-forward capability indication information in the RRC establishment completion message.

[0085] In some embodiments, when a UE receives a broadcast message from a base station not mounted on terrestrial equipment, it identifies whether the broadcast message carries store-and-forward mode operating status indication information. If the broadcast message carries store-and-forward mode operating status indication information, the UE can initiate the establishment of an RRC connection. In some embodiments, the UE triggers the establishment of an RRC connection by sending an RRC establishment request to the base station.

[0086] In some embodiments, the UE initiates the establishment of an RRC connection with a base station operating in store-and-forward mode only when it has not established an RRC connection with other NTN base stations (including cases where the connection is released due to store-and-forward mode), or when it has previously established an RRC connection with other NTN base stations (including cases where the connection is released due to store-and-forward mode) but the time exceeds a predetermined period, thereby avoiding resource waste and data loss caused by repeatedly establishing RRC connections.

[0087] In some embodiments, after establishing an RRC connection with the base station, the UE can send uplink data to the base station so that the base station can store the uplink data and send the uplink data to the core network after completing the initial UE context establishment with the core network.

[0088] In step S32, after the UE receives the first RRC release message from the base station, step S33 is triggered. In some embodiments, after the UE receives the RRC release message, it can first extract the release reason information included therein. If the release reason information is release due to store-and-forward mode, step S33 is triggered.

[0089] In step S33, the UE releases the RRC connection with the base station.

[0090] In some embodiments, if the first RRC release message contains timer information, the UE will not request to establish an RRC connection with other base stations in the same PLMN in store-and-forward mode within the time length indicated by the timer information. In some embodiments, the UE can identify the current base station from other base stations based on the non-terrestrial equipment identifier carried in the broadcast message.

[0091] In step S34, in response to receiving a paging message from the base station, step S35 is executed.

[0092] In step S35, the UE restores its RRC connection with the base station.

[0093] In some embodiments, after restoring the RRC connection with the base station, the UE can receive downlink data from the base station, which is obtained by the base station through the feeder link established with the ground core network during the time period between steps S33 and S34.

[0094] In some embodiments, after restoring the RRC connection with the base station, the UE can send uplink data to the base station. If the base station determines that the feeder link with the core network is not activated, it stores the uplink data so that it can be sent to the core network after the feeder link is activated.

[0095] As the base station leaves and returns to the area covering the UE's location, the RRC connection between the UE and the base station is restored, thereby improving communication continuity and reducing the risk of data loss.

[0096] Based on the method in the above embodiments, the UE can establish an RRC connection with the base station operating in store-and-forward mode, so that the base station can cooperate with the ground core network to complete the context establishment process after restoring the feeder link. The RRC connection can be restored when the base station moves back to the area covering the UE's location, thereby realizing non-real-time, intermittent data transmission. This provides a complete interaction process for signaling interaction and uplink / downlink data transmission between users and network devices in store-and-forward mode in NTN communication, effectively solving the problem of discontinuous coverage of NTN base stations and improving communication reliability.

[0097] Taking satellite communication as an example, the signaling flowcharts of some embodiments of the communication method disclosed herein are as follows: Figure 4As shown. During time periods T1 and T5, the satellite is located in an area where the base station can cover the UE's location, and the service link between the UE and the base station is available. During time period T3, the base station is located in an area where it can establish a connection with the terrestrial core network. There can be time intervals between T1, T3, and T5, such as T2 and T4. The length of each time period is determined based on specific circumstances and no upper or lower limits need to be set.

[0098] In scenario 401, the satellite is within the UE's communication range, and the UE measures the satellite cell. The UE learns from the system information block (SIB) broadcast by the satellite that the satellite cell is operating in S&F mode. In some embodiments, the system message also carries a satellite identifier.

[0099] In 402, the UE sends an RRC establishment request message to the satellite base station, requesting to establish a new connection from RRC_IDLE (idle state);

[0100] In steps 403-404, the UE and base station complete the RRC establishment process. The RRC establishment completion message carries the NAS message and S&F capability indication information.

[0101] In step 405, the UE can send uplink data to the base station. For example, in scenarios such as emergency calls, small data packets from the NB-IoT device can be encapsulated into a NAS PDU and transmitted as control plane signaling messages. In some embodiments, communication process 405 is a non-essential process generated according to needs and actual conditions.

[0102] In scenario 406, because the feeder link with the core network is not activated during satellite transit, user registration cannot be completed, and the base station (satellite) cannot obtain UE subscription data. Therefore, the base station will reject the UE's initial connection process. The base station sends an RRC release message to the UE, causing it to enter an idle or inactive state. In some embodiments, the RRC release message carries a new release reason value, indicating that the RRC connection needs to be suspended due to S&F operations.

[0103] In some embodiments, the RRC release message may also carry a new timer (optional) to indicate to the UE when it may retry the recovery procedure. During the duration of this timer value, the UE should not initiate connection attempts with any satellite cells operating in S&F mode within the same PLMN.

[0104] In some embodiments, the base station may use another rejection reason (e.g., other, congestion) to allow the UE to retry when the satellite passes by again for UEs that do not support S&F (e.g., UEs prior to Rel-19).

[0105] In step 407, if the base station determines that the feeder link to the core network is available, it sends an INITIAL UE MESSAGE message to the core network. This INITIAL UE MESSAGE includes the first uplink NAS message to be forwarded to the AMF and the UE location information. In this embodiment, the core network refers to the terrestrial core network.

[0106] In step 408, the core network initiates the UE Initial Context Setup procedure. The UE Initial Context Setup request includes store-and-forward operation indication information. The UE Initial Context Setup procedure is used to establish the necessary initial UE context at the base station, including PDU session context, security key, mobility restriction list, UE radio capabilities, and UE security capabilities. In addition, it also includes indication information that UE data needs to be cached at the base station due to store-and-forward operations.

[0107] In 409, the base station forwards the UE's uplink data to the satellite.

[0108] In 410, the base station receives and caches downlink data from the core network for the UE.

[0109] In 411, if necessary, the base station initiates a UE context suspension procedure to suspend the logical interface connection associated with the UE and the user plane transmission bearer with the core network, while keeping the UE context in the base station, including sending the UE location information (mapped cell ID, TA, etc. bound to the geographic region) to the core network carrying auxiliary information used during paging.

[0110] Each of the communication processes 409-411 described above is generated based on needs and actual circumstances, and is not a necessary process.

[0111] In 412-412a, the base station receives paging messages from the core network. When the base station moves and covers the area where the UE is located, it initiates a paging of the UE.

[0112] In 413, the UE resumes its RRC connection with the base station after receiving a paging message.

[0113] In sections 414-415, uplink and downlink data can be transmitted between the UE and the base station while the serving link is still operational. The base station stores the UE's uplink data until the feeder link becomes available again and forwards the data to the core network.

[0114] Based on the method in the embodiments shown above, the base station can adopt a store-and-forward working mode and release or suspend the RRC connection with the UE when the base station service link is available but a connection with the core network cannot be established; when the connection between the base station and the core network is available, a UE context is established and user data is exchanged; the UE context pause / resume procedure is used to support intermittent transmission characteristics, thereby providing a complete interaction process for signaling interaction and uplink / downlink data transmission between users and network devices in store-and-forward mode in NTN communication, effectively solving the problem of discontinuous coverage of NTN base stations and improving the reliability of communication.

[0115] In some embodiments, the signaling flowcharts of other embodiments of the communication method disclosed herein are as follows: Figure 5 As shown, the process is as follows: Figure 4 The subsequent process of the communication process shown.

[0116] In step 501, the base station moves to a location where the feeder link is available again. When the feeder link becomes available again, if the UE's communication process has not yet ended and the UE and the base station still need to maintain the store-and-forward mode, the base station initiates a UE context recovery procedure to the ground core network to restore the UE context, the suspended logical interface connection associated with the UE, and the user plane transmission bearer between the UE and the core network.

[0117] The subsequent communication process between 502 and 508 is the same as described above. Figure 4 The contents of 409-415 are the same or similar, and will not be repeated here.

[0118] This method enables interaction between the first UE and the core network by restoring previously established connections and contexts, avoiding excessive signaling burden, improving connection efficiency, and reducing the risk of data loss.

[0119] Schematic diagrams of some embodiments of the communication device 61 disclosed herein are shown below. Figure 6 As shown. Communication device 61 is a base station-side device, located in a non-ground device that carries the base station.

[0120] The first RRC connection establishment unit 612 is capable of establishing an RRC connection with the first UE, wherein the RRC establishment completion message carries store-and-forward capability indication information.

[0121] The first RRC connection release unit 613 can send a first RRC release message to the first UE when it is determined that the feeder link with the core network is not activated.

[0122] In some embodiments, the first RRC connection release unit 613 may initiate the release of the RRC connection immediately after the base station establishes an RRC connection and obtains the RRC establishment completion message of the first UE, thereby reducing the processing burden of the device and reducing the continuous occupation of base station and UE resources.

[0123] In some embodiments, the first RRC connection release unit 613 may actively initiate the release of the RRC connection after a predetermined duration of RRC connection establishment, thereby reducing the useless occupation of UE and base station resources while receiving uplink data.

[0124] Registration unit 614 can send the registration information of the first UE to the core network in response to activating the feeder link. In some embodiments, the core network can initiate an initial UE context establishment procedure for the first UE based on the registration information of the first UE. In some embodiments, the established initial UE context includes PDU session context, security key, mobility restriction list, UE radio capabilities, and UE security capabilities. In some embodiments, registration unit 614 can also initiate a context suspension procedure for the first UE to suspend the logical interface connection associated with the first UE and the username transmission bearer associated with the first UE and the core network, while keeping the first UE context in the base station. In some embodiments, during the context suspension procedure for the first UE, registration unit 614 can send UE location information (e.g., mapped cell ID, TA, etc. bound to a geographical area) used for auxiliary information during paging to the core network.

[0125] The first RRC connection restoration unit 615 can receive paging messages from the core network, and when it moves to a location area covering the first UE, it can initiate a paging to the first UE according to the paging message in order to restore the RRC connection with the first UE.

[0126] Such a communication device can adopt a store-and-forward working mode and release or suspend the RRC connection with the UE when the base station service link is available but a connection with the core network cannot be established; when the connection between the base station and the core network is available, it can establish a UE context and exchange user data; and use the UE context pause / resume procedure to support intermittent transmission characteristics, thereby providing a complete interaction process for signaling interaction and uplink and downlink data transmission between users and network devices in store-and-forward mode in NTN communication, effectively solving the problem of discontinuous coverage of NTN base stations and improving communication reliability.

[0127] In some embodiments, the communication device 61 further includes a broadcast unit 611, capable of transmitting store-and-forward mode operating status information via a broadcast message. The first UE sends an RRC establishment request to the base station based on the store-and-forward mode operating status information, and the base station establishes an RRC connection with the first UE based on the RRC establishment request. Such a device can be discovered and identified by the UE through a broadcast message carrying the store-and-forward mode operating status, improving the timeliness of establishing an RRC connection with the UE.

[0128] In some embodiments, the broadcast message sent by the broadcast unit 611 also includes a non-terrestrial device identifier (such as a satellite identifier). The UE can identify the non-terrestrial device where the base station that has established an RRC connection with it is located through the satellite identifier. In this way, when the RRC connection with the base station is restored in the future, the UE can identify the non-terrestrial device and avoid establishing RRC connections with base stations mounted on multiple non-terrestrial devices, thereby avoiding data loss and improving the reliability of communication.

[0129] In some embodiments, the communication device 61 further includes a first data transmission unit 616, which can acquire and store uplink data of the first UE after establishing an RRC connection with the first UE according to an RRC establishment request from the first UE; and send the uplink data to the core network after completing the initial UE context establishment with the core network, thereby improving the efficiency of UE data reaching the core network.

[0130] In some embodiments, the first data transmission unit 616 can receive downlink data from the core network after the UE initial context is established, and forward the downlink data to the UE after the first RRC connection recovery unit 615 restores the RRC connection with the first UE, thereby realizing downlink data transmission based on store-and-forward mode.

[0131] In some embodiments, the first data transmission unit 616 can receive uplink data from the first UE after the first RRC connection restoration unit 615 restores the RRC connection with the first UE, and forward the uplink data to the core network after the subsequent feeder link is restored, thereby realizing uplink data transmission based on store-and-forward mode.

[0132] In some embodiments, the communication device 61 further includes a context recovery unit 617, which can initiate context recovery for the first UE to the core network when the feeder link is activated at least a second time after the base station establishes an RRC connection with the UE (at which point the first UE has completed registration in the core network). Furthermore, when the communication device moves to a location area covering the first UE at least a third time after the base station establishes an RRC connection with the UE, it can initiate paging to the first UE according to a paging message to restore the RRC connection with the first UE.

[0133] Such a device can enable interaction between the first UE and the core network by restoring previously established connections and contexts, avoiding excessive signaling burden, improving connection efficiency, and reducing the risk of data loss.

[0134] Schematic diagrams of some embodiments of the communication device 72 disclosed herein are shown below. Figure 7 As shown. Communication device 72 is a user-side device located in the user equipment.

[0135] The second RRC connection unit 721 can establish an RRC connection with a base station operating in store-and-forward mode, and carry store-and-forward capability indication information in the RRC establishment completion message;

[0136] The second RRC connection release unit 722 can release the RRC connection with the base station in response to the first RRC release message from the base station. The base station sends the first RRC release message to the first UE when it determines that the feeder link with the core network is not activated.

[0137] The second RRC connection restoration unit 723 can restore the RRC connection with the base station in response to receiving a paging message from the base station.

[0138] Using this device, the UE can establish an RRC connection with the base station operating in store-and-forward mode, so that the base station can cooperate with the ground core network to complete the context establishment process after restoring the feeder link. The RRC connection can be restored when the base station moves back to the area covering the UE's location, thereby realizing non-real-time, intermittent data transmission. This provides a complete interaction process for signaling interaction and uplink / downlink data transmission between users and network devices in store-and-forward mode in NTN communication, effectively solving the problem of discontinuous coverage of NTN base stations and improving communication reliability.

[0139] In some embodiments, the communication device 72 further includes a second data transmission unit 724, which can send uplink data to the base station after establishing an RRC connection with the base station according to the store-and-forward mode working status indication information carried in the broadcast message. The base station stores the uplink data and sends the uplink data to the core network after completing the initial UE context establishment with the core network, thereby improving the efficiency of uplink data transmission to the core network.

[0140] In some embodiments, the second data transmission unit 724 can receive downlink data from the base station after the second RRC connection recovery unit 723 restores the RRC connection with the base station. The base station receives and stores downlink data from the core network after completing the initial UE context establishment with the core network, thereby realizing downlink data transmission based on store-and-forward mode.

[0141] In some embodiments, the second data transmission unit 724 can send uplink data to the base station after the second RRC connection restoration unit 723 restores the RRC connection with the base station. In this embodiment, the base station stores the uplink data when it is determined that the feeder link with the core network is not activated, so that it can be sent to the core network after the feeder link is activated, thereby realizing uplink data transmission based on store-and-forward mode.

[0142] A schematic diagram of the structure of an embodiment of the communication device disclosed herein is shown below. Figure 8 As shown, the communication device includes a memory 801 and a processor 802. The memory 801 can be a disk, flash memory, or any other non-volatile storage medium. The memory stores instructions in the corresponding embodiments of the communication method described above. The processor 802 is coupled to the memory 801 and can be implemented as one or more integrated circuits, such as a microprocessor or microcontroller. The processor 802 executes the instructions stored in the memory, providing a complete interaction process for signaling interaction and uplink / downlink data transmission between users and network devices in the store-and-forward mode of NTN communication. This effectively solves the problem of discontinuous coverage of NTN base stations and improves communication reliability.

[0143] In one embodiment, it can also be as follows: Figure 9 As shown, the communication device 900 includes a memory 901 and a processor 902. The processor 902 is coupled to the memory 901 via a BUS bus 903. The communication device 900 can also be connected to an external storage device 905 via a storage interface 904 to access external data, and can also be connected to a network or another computer system (not shown) via a network interface 906. Further details are omitted here.

[0144] In this embodiment, by storing data instructions in the memory and then processing the instructions by the processor, a complete interaction process can be provided for signaling interaction and uplink and downlink data transmission between users and network devices in the store-and-forward mode of NTN communication. This effectively solves the problem of discontinuous coverage of NTN base stations and improves the reliability of communication.

[0145] In another embodiment, a computer-readable storage medium stores computer program instructions that, when executed by a processor, implement the steps of the method in the corresponding embodiment of the communication method. Those skilled in the art will understand that embodiments of this disclosure can be provided as methods, apparatus, or computer program products. Therefore, this disclosure can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this disclosure can take the form of a computer program product embodied on one or more computer-usable non-transitory storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0146] Schematic diagrams of some embodiments of the communication system disclosed herein are shown below. Figure 10 As shown.

[0147] Base station 1010 can execute any of the communication methods mentioned above that are performed by a base station. Base station 1010 may include the communication methods mentioned above... Figure 6 The communication device in the illustrated embodiment.

[0148] The first UE 1020 can execute any of the communication methods mentioned above. The first UE 1020 may include the communication methods mentioned above. Figure 7 The communication device in the illustrated embodiment. The system may include at least one first UE.

[0149] Core network 1030 is a terrestrial core network (the entire core network when it is entirely located on the ground, or the portion of the core network located on the ground when it is partially located in non-terrestrial equipment). In some embodiments, the first UE, base station, and core network may adopt the following... Figure 4 , 5 The process in the illustrated embodiment implements NTN communication based on store-and-forward mode.

[0150] In such a communication system, when the base station service link is available but a connection with the core network cannot be established, the base station can adopt a store-and-forward working mode and release or suspend the RRC connection with the UE; when the connection between the base station and the core network is available, the base station can establish a UE context and exchange user data; and use the UE context pause / resume procedure to support intermittent transmission characteristics. This provides a complete interaction process for signaling interaction and uplink / downlink data transmission between users and network devices in store-and-forward mode in NTN communication, effectively solving the problem of discontinuous coverage of NTN base stations and improving communication reliability.

[0151] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0152] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0153] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0154] This concludes the detailed description of the present disclosure. To avoid obscuring the concept of the disclosure, some details known in the art have not been described. Those skilled in the art will fully understand how to implement the technical solutions disclosed herein based on the above description.

[0155] The methods and apparatus of this disclosure may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of this disclosure are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, this disclosure may also be implemented as a program recorded on a recording medium, the program including machine-readable instructions for implementing the methods according to this disclosure. Thus, this disclosure also covers recording media storing programs for performing the methods according to this disclosure.

[0156] It should be noted that the terms "first," "second," etc., used in the specification, claims, and drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and not to limit them; although this disclosure has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this disclosure or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of this disclosure, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in this disclosure.

Claims

1. A communication method, comprising: The base station establishes a Radio Resource Control (RRC) connection with the first User Equipment (UE), wherein the RRC establishment completion message carries store-and-forward capability indication information; If it is determined that the feeder link between the base station and the core network is not activated, the base station sends a first RRC release message to the first UE; In response to activating the feeder link, the base station sends the registration information of the first UE to the core network; The base station receives a paging message from the core network, and when it moves to a location area covering the first UE, it initiates a paging to the first UE in order to restore the RRC connection with the first UE.

2. The communication method according to claim 1 further includes: The base station sends store-and-forward mode operating status information via broadcast message. The first UE sends an RRC establishment request to the base station based on the store-and-forward mode operating status information. The base station establishes an RRC connection with the first UE based on the RRC establishment request.

3. The communication method according to claim 2, wherein, The broadcast message also includes a satellite identifier.

4. The communication method according to claim 1, wherein, The first RRC release message includes a first release reason information, which indicates that the RRC connection needs to be paused due to a store-and-forward operation.

5. The communication method according to claim 4, wherein, The first RRC release message also includes timer information, which indicates the time for pausing the user equipment's request to establish an RRC connection with a base station in the same PLMN in store-forward mode.

6. The communication method according to claim 1, further comprising: The base station establishes an RRC connection with the second UE, wherein the second UE does not have store-and-forward capability; When the base station determines that the feeder link between the base station and the core network is not activated, it sends a second RRC release message to the second UE. The second RRC release message includes a second release reason information, which is different from the first release reason information.

7. The communication method according to claim 1, further comprising: After sending the registration information of the first UE to the core network, the base station obtains indication information indicating that the data of the first UE is cached in the base station. The core network initiates the establishment of the UE initial context based on the registration information and sends the indication information.

8. The communication method according to claim 1, further comprising: The base station initiates a first UE context suspension procedure to the core network, storing the context of the first UE in the base station. The first UE context suspension procedure is used to suspend the logical interface connection associated with the first UE and the user plane transmission bearer with the core network.

9. The communication method according to claim 7, further comprising: During the first UE context pause procedure, the base station sends the location information of the first UE to the core network. The location information includes at least one of cell identifier or tracking area identifier.

10. The communication method according to claim 1, further comprising: After establishing an RRC connection with the first UE based on the RRC establishment request from the first UE, the base station acquires and stores the uplink data of the first UE. Once the initial context establishment between the UE and the core network is completed, the uplink data is sent to the core network.

11. The communication method according to claim 1, further comprising: Upon completion of the initial UE context establishment with the core network, downlink data from the core network is received and stored. After restoring the RRC connection with the first UE, the downlink data is sent to the first UE.

12. The communication method according to claim 1, further comprising: After the base station restores the RRC connection with the first UE, it receives uplink data from the first UE. If the base station determines that the feeder link with the core network is not activated, it stores the uplink data so that it can be sent to the core network after the feeder link is activated.

13. The communication method according to claim 1, further comprising: In response to activating the feeder link, the base station initiates context recovery for the first UE to the core network; The base station receives a paging message from the core network, and when it moves to a location area covering the first UE, it initiates a paging to the first UE in order to restore the RRC connection with the first UE.

14. The communication method according to claim 1 or 13, further comprising: After restoring the RRC connection with the first UE, the base station performs at least one of the following: Receive and store the uplink data of the first UE until the feeder link becomes available again and forward the data to the core network; or The cached downlink data from the core network is sent to the first UE.

15. A communication method, comprising: The user equipment (UE) establishes a radio resource control (RRC) connection with the base station operating in store-and-forward mode, and carries store-and-forward capability indication information in the RRC establishment completion message; In response to a first RRC release message from the base station, the RRC connection with the base station is released, wherein the base station sends the first RRC release message to the first UE when it determines that the feeder link with the core network is not activated; In response to receiving a paging message from the base station, the RRC connection with the base station is restored.

16. The communication method according to claim 15, further comprising: Receive broadcast messages from the base station; Based on the store-and-forward mode operating status indication information carried in the broadcast message, an RRC establishment request is sent to the base station.

17. The communication method according to claim 16, further comprising: After establishing an RRC connection with the base station based on the store-and-forward mode operating status indication information carried in the broadcast message, uplink data is sent to the base station. The base station stores the uplink data and sends the uplink data to the core network after completing the initial UE context establishment with the core network.

18. The communication method according to claim 15, further comprising: After restoring the RRC connection with the base station, downlink data is received from the base station, wherein the base station receives and stores downlink data from the core network after completing the initial UE context establishment with the core network.

19. The communication method according to claim 15, further comprising: After restoring the RRC connection with the base station, uplink data is sent to the base station. If the base station determines that the feeder link with the core network is not activated, it stores the uplink data so that it can be sent to the core network after the feeder link is activated.

20. The communication method according to claim 15, further comprising: After restoring the RRC connection with the base station, perform at least one of the following: Uplink data is sent to the base station, wherein the base station receives and stores the uplink data of the first UE until the feeder link becomes available again and forwards the data to the core network; or Receive downlink data from the core network cached by the base station.

21. A communication device, comprising: The first Radio Resource Control (RRC) connection establishment unit is configured to establish an RRC connection with the first User Equipment (UE), wherein the RRC establishment completion message carries store-and-forward capability indication information. The first RRC connection release unit is configured to send a first RRC release message to the first UE when it is determined that the feeder link with the core network is not activated; The registration unit is configured to send the registration information of the first UE to the core network in response to activating the feeder link; The first RRC connection recovery unit is configured to receive a paging message from the core network, and, when moving to a location area covering the first UE, to initiate a paging to the first UE in order to restore the RRC connection with the first UE.

22. The communication device according to claim 21, further comprising: The broadcast unit is configured to send store-and-forward mode operating status information via broadcast messages, wherein the first UE sends an RRC establishment request to the base station according to the store-and-forward mode operating status information, and the base station establishes an RRC connection with the first UE according to the RRC establishment request.

23. The communication device according to claim 21, further comprising: The first data transmission unit is configured to, after establishing an RRC connection with the first UE according to an RRC establishment request from the first UE, acquire and store the uplink data of the first UE; and, after completing the initial UE context establishment with the core network, send the uplink data to the core network.

24. The communication device according to claim 21, further comprising: The context recovery unit is configured to initiate context recovery of the first UE to the core network in response to activating the feeder link; The first RRC connection recovery unit is also configured to receive a paging message from the core network, and, if it moves to a location area covering the first UE, to initiate a paging to the first UE in order to restore the RRC connection with the first UE.

25. A communication device, comprising: The second Radio Resource Control (RRC) connection unit is configured to establish an RRC connection with a base station operating in store-and-forward mode, and to carry store-and-forward capability indication information in the RRC establishment completion message. The second RRC connection release unit is configured to release the RRC connection with the base station in response to a first RRC release message from the base station, wherein the base station sends the first RRC release message to the first user equipment UE when it determines that the feeder link with the core network is not activated; The second RRC connection restoration unit is configured to restore the RRC connection with the base station in response to receiving a paging message from the base station.

26. The communication apparatus according to claim 25, further comprising: The second data transmission unit is configured to send uplink data to the base station after establishing an RRC connection with the base station based on the store-and-forward mode working status indication information carried in the broadcast message. The base station stores the uplink data and sends the uplink data to the core network after completing the initial UE context establishment with the core network.

27. A communication device, comprising: Memory; as well as A processor coupled to the memory, the processor being configured to perform the method as described in any one of claims 1 to 20 based on instructions stored in the memory.

28. A computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the method of any one of claims 1 to 20.

29. A computer program product comprising a computer program or instructions which, when executed by a processor, implement the method of any one of claims 1 to 20.

30. A communication system, comprising: The base station is configured to perform the method described in any one of claims 1 to 14; and The core network is configured to receive registration information from a first user equipment (UE) at the base station and send paging messages to the base station.

31. The communication system according to claim 29, further comprising: The first UE is configured to perform the method described in any one of claims 15 to 20.

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