Communication maintenance method and device

Abstract

An embodiment of the present invention provides a communication maintaining method and device, which includes the steps of: a terminal device receiving a first notification message sent by a relay device, where a cause indication value or an indication type in the first notification message is relay device handover, cell selection or reselection, or Uu interface radio link failure; and the terminal device determining to maintain a connection with the relay device and suspending data transmission between the terminal device and the relay device.

Description

[Technical field]

[0001] The present invention relates to the field of communications. [Background technology]

[0002] In release 17, sidelink relay is considered, which includes the UE-to-Network relay scenario, where it is assumed that the Uu link of the relay UE uses the NR (New Radio) Uu interface, and the PC5 interface between the remote UE and the relay uses the NR sidelink.

[0003] Figure 1 is a schematic diagram of UE-to-Network relay scenarios. As shown in Figure 1, in scenario (a), remote UE11 is out of the coverage range of the network, and relay UE12 (i.e., UE-to-NW relay) is in the coverage range of the network, in scenario (b), remote UE11 and relay UE12 are all in the coverage range of the network, and in scenario (c), remote UE11 and relay UE12 are in the coverage range of different cells.

[0004] In the 3GPP (Third Generation Partnership Project) discussions on Layer-2 (L2) UE-to-Network relay, the following was agreed upon:

[0005] When a relay UE detects a radio link failure (Uu Radio link failure: Uu RLF) of the Uu interface, the relay UE may send a PC5-S message to a remote UE connected to it, which may trigger a relay reselection of the remote UE.

[0006] When the relay UE performs a handover to another gNB, the relay UE may send a PC5-S message to the remote UE connected to it, which may trigger a relay reselection of the remote UE.

[0007] When a relay UE in an idle or inactive state performs cell selection or cell reselection, the relay UE may send an indication / message to a remote UE connected to it, which may trigger a relay reselection of the remote UE.

[0008] When a Uu RLF occurs in a relay UE, a PC5-RRC (Radio Resource Control) message may be used to send an indication to a remote UE. Figure 2 is a schematic diagram of this scenario.

[0009] When the relay UE performs handover, the PC5-RRC message is used to notify the remote UE.

[0010] When the relay UE performs cell selection or cell reselection, the PC5-RRC message is used to notify the remote UE.

[0011] The above description of the background art is merely for the purpose of more clearly and completely explaining the configurations of the present invention and for the understanding of those skilled in the art, and should not be construed as meaning that these configurations are well known to those skilled in the art just because they are described in the background art of the present invention. Summary of the Invention [Problem to be solved by the invention]

[0012] According to the discovery of the present inventor, when receiving the PC5-RRC message, the remote UE may decide to maintain the PC5-RRC connection with the relay UE. In this case, the remote UE does not perform the PC5-RRC connection release process, which causes the following two problems:

[0013] Problem 1: If the remote UE decides to maintain a PC5-RRC connection with the relay UE and continues to transmit uplink signaling or uplink data via the relay UE, these signaling / data may not reach the network device (e.g., if the relay UE detects a Uu RLF) and may be lost.

[0014] Problem 2: If the remote UE decides to maintain the PC5-RRC connection with the relay UE, assuming that the remote UE suspends data transmission between the relay UE, then when the relay UE successfully recovers the Uu RLF and the remote UE does not know this situation, the remote UE cannot resume communication with the network through the relay UE. In addition, the remote UE may decide to release the PC5-RRC connection with the relay UE and perform remote UE reselection depending on the implementation, which increases the service interruption time for the relay UE to communicate with the network.

[0015] To address the above-mentioned problems and other similar problems, embodiments of the present invention provide a communication maintenance method and apparatus. [Means for solving the problem]

[0016] In one aspect of an embodiment of the present invention, a communication maintenance device configured in a terminal device is provided, the device including: a receiving unit that receives a first notification message transmitted by a relay device, wherein a cause indication value or an instruction type in the first notification message is relay device handover, cell selection or reselection, or Uu interface radio link failure; and a processing unit that decides to maintain a connection with the relay device and suspends data transmission between the relay device.

[0017] Another aspect of an embodiment of the present invention provides a communication maintenance device configured in a relay device, the device including: a first transmitting unit that transmits a first notification message to a terminal device, wherein a cause indication value or an instruction type in the first notification message is a handover of the relay device, a cell selection or reselection, or a Uu interface radio link failure; and a processing unit that buffers or stores signaling and / or data from the terminal device.

[0018] Another aspect of an embodiment of the present invention provides a communication maintenance device configured in a terminal device, the device including: a first processing unit that maintains a connection with the relay device after the terminal device receives a first notification message transmitted by the relay device; and a second processing unit that restores data transmission between the terminal device and the relay device after the terminal device receives a second notification message transmitted by the relay device.

[0019] Another aspect of an embodiment of the present invention provides a communication maintenance device configured in a relay device, the device including: a transmitting unit that transmits a first notification message to a terminal device; and a processing unit that triggers the second notification message or transmits the second notification message to the terminal device when at least one of the following conditions is satisfied: the relay device has not received a PC5-S release message from the terminal device; the relay device has successfully executed a Uu interface radio link failure recovery process; the relay device has successfully executed a handover process; and the relay device has completed cell selection or reselection.

[0020] One of the advantageous effects of the embodiment of the present invention is as follows: According to the embodiment of the present invention, data loss can be avoided when the remote UE maintains a connection with the relay UE, and the remote UE can restore communication with the network through the relay UE after the relay UE recovers the Uu RLF, or after the handover is completed, or after the cell selection (reselection) is completed, the power consumption for the cell selection or reselection or relay by the remote UE can be reduced, and the interruption time of the data transmission by the remote UE can be shortened.

[0021] As shown in the following description and drawings, certain embodiments of the present invention are disclosed in detail to show the manner in which the principles of the present invention can be employed. However, the scope of the embodiments of the present invention is not limited to these. The embodiments of the present invention include modifications, alterations and equivalents within the spirit and scope of the appended claims.

[0022] Features described and / or illustrated in one embodiment may be used in the same or similar manner in one or more other embodiments and may be combined with or substituted for features in the other embodiments.

[0023] It should be noted that in this text, the term "including / having" means the presence of a feature, element, step or component, and does not exclude the presence or addition of one or more other features, elements, steps or components. [Brief description of the drawings]

[0024] Elements and features depicted in one drawing and one embodiment of the present invention may be combined with elements and features shown in one or more drawings or embodiments, and in the drawings, like reference numerals may designate corresponding elements in multiple drawings and may designate corresponding elements used in more than one embodiment.

[0025] The drawings included herein are used to further understand the embodiments of the present invention, constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the description of the words, explain the principles of the present invention. Note that the drawings described below are merely some of the embodiments of the present invention, and those skilled in the art can easily imagine other drawings based on these drawings. [Figure 1] FIG. 1 is a schematic diagram of a UE-to-Network relay scenario. [Diagram 2] This is a schematic diagram of notifying a remote UE via a PC5-RRC message when a Uu RLF occurs in a relay UE. [Diagram 3] 1 is a schematic diagram of an example of a communication maintaining method according to a first embodiment of the present invention; [Figure 4] FIG. 11 is a schematic diagram of an example of a communication maintaining method according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is a schematic diagram of an example of a communication maintaining method according to a third embodiment of the present invention. [Figure 6] FIG. 11 is a schematic diagram of an example of a communication maintaining method according to a fourth embodiment of the present invention. [Figure 7] FIG. 11 is a schematic diagram of an example of a communication maintaining device according to a fifth embodiment of the present invention. [Figure 8] FIG. 11 is a schematic diagram of another example of a communication maintaining device according to the fifth embodiment of the present invention. [Figure 9]FIG. 11 is a schematic diagram of another example of a communication maintaining device according to the fifth embodiment of the present invention. [Figure 10] FIG. 11 is a schematic diagram of another example of a communication maintaining device according to the fifth embodiment of the present invention. [Figure 11] 1 is a schematic diagram of a communication system according to an embodiment of the present invention. [Figure 12] FIG. 2 is a schematic diagram of a terminal device according to an embodiment of the present invention. [Figure 13] 1 is a schematic diagram of a relay device according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The above and other features of the present invention will become apparent from the following description. In the specification and drawings, specific embodiments of the present invention are disclosed in detail, and some of the embodiments in which the principles of the present invention can be adopted are shown. However, the present invention is not limited to the described embodiments. The present invention includes all modifications, variations, and equivalents within the scope of the appended claims. Each embodiment of the present invention will be described below with reference to the drawings. These embodiments are merely illustrative and do not limit the present invention.

[0027] In embodiments of the present invention, the terms "first", "second", etc. are used in the title to distinguish different elements, but do not represent the spatial arrangement or temporal order of these elements, and these elements are not limited to these terms. The term "and / or" includes any and all combinations of one or more of the terms listed in the associated list. The terms "including", "comprising", "having", etc. refer to the presence of listed features, elements, elements or components, but do not exclude the presence or addition of one or more other features, elements, elements or components.

[0028] In the embodiments of the present invention, the singular forms "a", "the", etc., include the plural forms and should be understood broadly as "one kind" or "a class", and are not limited to "one". In addition, the term "said" should be understood to include both the singular and the plural forms, unless the context clearly indicates otherwise. In addition, the term "described in" should be understood to mean "described at least in part", and the term "based on" should be understood to mean "based at least in part on", unless the context clearly indicates otherwise.

[0029] In an embodiment of the present invention, the term "communication network" or "wireless communication network" may refer to a network conforming to any communication standard, such as, for example, Long Term Evolution (LTE), Advanced Long Term Evolution (LTE-A, LTE-Advanced), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), etc.

[0030] Additionally, communications between devices in a communication system may occur according to any stage of communication protocols, including, but not limited to, 1G (generation), 2G, 2.5G, 2.75G, 3G, 4G, 4.5G, and future 5G, New Radio (NR), and / or other currently known or future developed communication protocols.

[0031] In the embodiment of the present invention, the term "network device" refers to a device in a communication system, for example, allowing a terminal device to access the communication system and providing a service to the terminal device. The network device may include, but is not limited to, a base station (BS), an access point (AP), a transmission reception point (TRP), a broadcast transmitter, a mobility management entity (MME), a gateway, a server, a radio network controller (RNC), a base station controller (BSC), etc.

[0032] A base station may include, but is not limited to, a Node B (NodeB or NB), evolved Node B (eNodeB or eNB), 5G base station (gNB), etc., as well as a Remote Radio Head (RRH), a Remote Radio Unit (RRU), a relay, or a low power node (e.g., femto, pico, etc.). Also, the term "base station" may include some or all of these functionalities, and each base station may provide communication coverage for a particular geographic area. The term "cell" may refer to a base station and / or its coverage area depending on the context in which the term is used.

[0033] In the embodiments of the present invention, the term "User Equipment" (UE) or "Terminal Equipment" (TE) refers to an apparatus that accesses a communication network and receives a network service via, for example, a network device. The terminal apparatus may be fixed or mobile, and may be referred to as a mobile station (MS), a terminal, a subscriber station (SS), an access terminal (AT), a station, etc.

[0034] The terminal device may include, but is not limited to, a cellular phone, a personal digital assistant (PDA), a wireless modulation / demodulation device, a wireless communication device, a handheld device, a machine type communication device, a laptop computer, a cordless phone, a smartphone, a smart watch, a digital camera, and the like.

[0035] Also, for example, in a scenario such as the Internet of Things (IoT), the user equipment may be a monitoring or measuring device or equipment, and may include, but is not limited to, a Machine Type Communication (MTC) terminal, an in-vehicle communication terminal, a Device to Device (D2D) terminal, a Machine to Machine (M2M) terminal, and the like.

[0036] At the last 3GPP meeting, the following was agreed upon:

[0037] When the PC5-RRC message for notification is received, the remote UE decides whether to release or maintain the unicast PC5 link with the relay UE depending on the implementation of the remote UE. If the remote UE decides to release the unicast PC5 link, the remote UE triggers a conventional Layer 2 release process and performs relay reselection.

[0038] For the remote UE to decide whether to trigger relay selection or reselection, the PC5-RRC message sent by the relay UE includes a cause value, namely handover or cell selection (reselection) or Uu RLF.

[0039] In the standard for SL relay, the PC5-RRC message is referred to as a Sidelink Notification Message. The standard describes the operation of the remote UE when it receives the PC5-RRC message as follows:

[0040] [Table 1] Regarding re-establishment of the RRC connection, the standard states as follows:

[0041] [Table 2] However, as mentioned above, when receiving the PC5-RRC message, the remote UE may decide to maintain the PC5-RRC connection with the relay UE. In this case, the remote UE does not perform the PC5-RRC connection release process. As a result, the signaling or data sent by the remote UE through the relay UE cannot reach the network side, or after the relay UE successfully recovers the Uu RLF, the remote UE does not know this situation and cannot resume communication with the network through the relay UE.

[0042] In view of the above problems, the present invention has been proposed. Various embodiments of the present invention will be described below with reference to the drawings. These embodiments are merely illustrative and do not limit the present invention.

[0043] <Example 1> An embodiment of the present invention provides a method for maintaining communication and is described from the terminal device side.

[0044] 3 is a schematic diagram of an example of a communication maintaining method according to an embodiment of the present invention. As shown in FIG. 3, the method includes the following steps:

[0045] Step 301: The terminal device receives a first notification message sent by a relay device, in which a cause indication value or an indication type is a relay device handover, a cell selection or reselection, or a Uu interface radio link failure.

[0046] Step 302: The terminal device decides to maintain the connection with the relay device, and suspends data transmission between the terminal device and the relay device.

[0047] In an embodiment of the present invention, when a handover, a cell selection or reselection, or a Uu RLF occurs in the relay device, the relay device transmits the above-mentioned first notification message to the terminal device. The terminal device is notified of the situation by a cause indication value or an instruction type in the first notification message. The cause indication value or the instruction type is, for example, a handover of the relay device, a cell selection or reselection, or a Uu interface radio link failure. When the terminal device receives the first notification message, the terminal device may suspend data transmission with the relay device. This prevents the relay device from continuing to transmit uplink signaling and / or uplink data via the relay device, thereby preventing the signaling / data from being unable to reach the network side.

[0048] In the above embodiment, the terminal device may decide whether to maintain the connection with the relay device depending on its implementation.

[0049] In some embodiments, the terminal device may suspend data transmission with the relay device after determining whether to maintain the connection with the relay device. Alternatively, the terminal device may determine whether to maintain the connection with the relay device after suspending data transmission with the relay device. Alternatively, the terminal device may suspend data transmission with the relay device and determine whether to maintain the connection with the relay device in the RRC re-establishment process after initiating an RRC connection re-establishment process.

[0050] In the embodiment of the present invention, the above-mentioned first notification message may be an existing PC5 RRC message. For the content related to the PC5-RRC message, reference may be made to the related art, and the description thereof will be omitted here. The present invention is not limited thereto, and the above-mentioned first notification message may be another message.

[0051] In an embodiment of the present invention, when a terminal device is in a connected state (RRC_CONNECTED state), the terminal device may suspend data transmission between the terminal device and the relay device by performing at least one of the following operations: Suspend all radio bearers (RBs) except SRB0 (signaling radio bearer 0), suspending the PC5 RLC (Radio Link Control) channels corresponding to all radio bearers other than SRB0; suspending signaling radio bearer 0 (SRB0); suspending a PC5 interface radio link control (PC5 RLC) channel corresponding to signaling radio bearer 0 (SRB0); Resetting the MAC (medium access control), and This includes, but is not limited to, ceasing or suspending transmission of physical layer data or signaling to the relay device.

[0052] In an embodiment of the present invention, when the terminal device is in an idle or inactive state (RRC_Idle or RRC_Inactive state), the terminal device may suspend data transmission between the terminal device and the relay device by performing at least one of the following operations: suspending SRB0 and / or the PC5 RLC corresponding to SRB0; Resetting the MAC (medium access control), sending a system information request (SI request) to the relay device to request an update of system information; and This includes, but is not limited to, initiating cell selection or cell reselection.

[0053] For example, when the relay device transmits the above-mentioned first notification message to the terminal device when the cell reselection or handover is completed, the terminal device may transmit a system information request to the relay device to request an update of the system information. Alternatively, if the relay device does not receive a system information request from the terminal device, the relay device may transmit the system information of the serving cell after the reselection or handover of the relay device to the terminal device when the cell reselection or handover is completed.

[0054] In the above embodiments, the embodiments of the present invention are merely described as examples, but the present invention is not limited thereto, and may be appropriately modified based on the above embodiments. For example, the trigger conditions in the above embodiments may be used alone, or one or more of the trigger conditions in the above embodiments may be used in combination.

[0055] According to the method according to the embodiment of the present invention, data loss can be avoided when a remote UE maintains a connection with a relay UE.

[0056] <Example 2> The embodiment of the present invention provides a communication maintaining method, which is explained from the relay device side.

[0057] 4 is a schematic diagram of an example of a communication maintaining method according to an embodiment of the present invention. As shown in FIG. 4, the method includes the following steps:

[0058] Step 401: A relay device sends a first notification message to a terminal device, in which a cause indication value or an indication type is a handover of the relay device, a cell selection or reselection, or a Uu interface radio link failure.

[0059] Step 402: The relay device buffers or stores signaling and / or data from the terminal device.

[0060] In the embodiment of the present invention, when a handover, a cell selection or reselection, or a Uu RLF occurs in the relay device, the relay device sends the above-mentioned first notification message to the terminal device. The terminal device is notified of this situation by a cause indication value or an indication type in the first communication message. The cause indication value or indication type is, for example, a handover of the relay device, a cell selection or reselection, or a Uu interface radio link failure. Different from the first embodiment, in the embodiment of the present invention, the terminal device does not need to suspend data transmission between the relay device and the relay device, and the relay device buffers or stores the signaling / data from the terminal device. Thus, the relay device can transmit the buffered or stored signaling / data to the network side after the handover is completed, the cell selection or reselection is completed, or the Uu RLF is restored, and data loss can be avoided.

[0061] In the embodiment of the present invention, the above-mentioned first notification message may be an existing PC5 RRC message. For the content related to the PC5-RRC message, reference may be made to the related art, and the description thereof will be omitted here. The present invention is not limited thereto, and the above-mentioned first notification message may be another message.

[0062] In an embodiment of the present invention, the above signaling / data may be signaling / data sent by a terminal device to a network device via a relay device. PC5 interface signaling, such as an SI request sent by a terminal device to a relay device, may or may not be buffered by the relay device, but the present invention is not limited thereto.

[0063] In some embodiments, the relay device may buffer or store signaling / data from the terminal device at the PC5 interface, for example, the terminal device may buffer or store PC5 SRAP SDUs (Sidelink Relay Adaptation Protocol Service Data Units) and / or PC5 SRAP PDUs (Sidelink Relay Adaptation Protocol Protocol Data Units) and / or PC5 RLC SDUs (Radio Link Control Service Data Units) and / or PC5 RLC PDUs (Radio Link Control Protocol Data Units) and / or PC5 MAC SDUs (Medium Access Control Service Data Units) and / or PC5 MAC PDUs (Medium Access Control Protocol Data Units) and / or PC5 physical layer data, etc. at the PC5 interface, but the invention is not limited thereto.

[0064] In some embodiments, the relay device may buffer signaling and / or data from the terminal device at the Uu interface. For example, the terminal device may buffer or store Uu SRAP SDUs and / or Uu SRAP PDUs and / or Uu RLC SDUs and / or Uu RLC PDUs and / or Uu MAC SDUs and / or Uu MAC PDUs and / or Uu physical layer data, etc., at the Uu interface, but the present invention is not limited thereto.

[0065] In an embodiment of the present invention, the relay device may transmit the buffered or stored signaling and / or data to the network device after the handover is completed, or after the cell selection or reselection is completed, or after the Uu interface RLF is restored, thereby avoiding data loss.

[0066] The above-mentioned embodiments are merely illustrative of the embodiments of the present invention, but the present invention is not limited thereto, and may be appropriately modified based on the above-mentioned embodiments. For example, the above-mentioned embodiments may be used alone, or one or more of them may be used in combination.

[0067] According to the method of the embodiment of the present invention, the remote UE can continue to transmit uplink signaling or uplink data to the relay UE, and the relay UE can avoid data loss by buffering / storing such signaling / data.

[0068] <Example 3> An embodiment of the present invention provides a method for maintaining communication and is described from the terminal device side.

[0069] 5 is a schematic diagram of an example of a communication maintaining method according to an embodiment of the present invention. As shown in FIG. 5, the method includes the following steps:

[0070] Step 501: After receiving a first notification message sent by a relay device, the terminal device maintains a connection with the relay device.

[0071] Step 502: After the terminal device receives the second notification message sent by the relay device, the terminal device restores data transmission between the terminal device and the relay device.

[0072] In an embodiment of the present invention, the relay device sends a first notification message to the terminal device after handover, cell selection or reselection, or Uu RLF occurs, and sends a second notification message to the terminal device after handover, cell selection or reselection is completed, or Uu RLF is restored. Then, the terminal device maintains a connection with the relay device after receiving the first notification message, and restores data transmission with the relay device after receiving the second notification message. This allows the terminal device to restore communication with the network through the relay device, reduces the cell selection or reselection by the terminal device, or the power consumption of the relay device, and shortens the interruption time of the data transmission of the terminal device.

[0073] In an embodiment of the present invention, the cause indication value or the indication type in the first notification message is, for example, relay device handover, cell selection or reselection, or Uu interface radio link failure. The cause indication value or the indication type in the second notification message is, for example, relay device handover completion, cell selection or reselection completion, or Uu interface radio link failure recovery.

[0074] In an embodiment of the present invention, the first notification message and the second notification message may be realized by the same PC5 RRC message, for example, a NotificationMessageSidelink message, and the first notification message and the second notification message may be distinguished by different cause values ​​or indication types. The present invention is not limited thereto, and the first notification message and the second notification message may be realized by different PC5 RRC messages.

[0075] In an embodiment of the present invention, the terminal device may restore data transmission to and from the relay device by performing at least one of the following operations: resume all radio bearers except SRB0, Re-establishing PDCP (Packet Data Convergence Protocol) for SRB2 and DRB (Data Radio Bearer); re-establishing the PC5 RLC channels corresponding to all radio bearers other than SRB0 or ​​re-establishing the RLC channels corresponding to all radio bearers other than SRB0; Resuming SRB1, re-establishing the PDCP of SRB1; Resuming the PC5 RLC channel corresponding to SRB1 or re-establishing the RLC (e.g., PC5 RLC entity) of SRB1; resuming transmission to the relay device; Applying the default configuration for SRB1, e.g. SL-RLC1; sending a system information request (SI request) to the relay device to request updated system information; Stopping or terminating the cell selection or reselection process; and This includes, but is not limited to, stopping or terminating the RRC connection re-establishment process.

[0076] In an embodiment of the present invention, the terminal device may use a timer or a predefined period to wait for the second notification message from the relay device.

[0077] In some embodiments, when the terminal device receives the above-mentioned first notification message, it starts a timer, and when the terminal device receives the second notification message while the timer is running, the terminal device stops the timer.

[0078] In the above embodiment, if the terminal device does not receive the second notification message during the operation of the timer, after the timer times out, the terminal device: initiating an RRC connection re-establishment; Continue with the RRC connection re-establishment; Releasing the PC5 connection with the relay device; and The mobile station may perform at least one of the following operations: performing cell selection or relay selection.

[0079] This prevents the terminal device from waiting indefinitely for the second notification message, and further improves the reliability of communication.

[0080] In the above embodiment, the timer may be predefined or configured by the network device, but the present invention is not limited thereto.

[0081] In some embodiments, if the terminal device does not receive the second notification message within a predefined period of time after receiving the first notification message, the terminal device: initiating an RRC connection re-establishment; Continue with the RRC connection re-establishment; Releasing the PC5 connection with the relay device; and The method performs at least one of the following operations: performing cell selection or relay selection.

[0082] This limits the time that the terminal device waits for the second notification message to a predefined period, thereby avoiding resource waste and communication interruptions that would result from the terminal device waiting indefinitely for the second notification message, and improving communication reliability.

[0083] The above-mentioned embodiments are merely illustrative of the embodiments of the present invention, but the present invention is not limited thereto, and may be appropriately modified based on the above-mentioned embodiments. For example, the above-mentioned embodiments may be used alone, or one or more may be combined, for example, the third embodiment and the first embodiment may be combined.

[0084] According to a method of an embodiment of the present invention, a terminal device can restore communication with a network via a relay device, thereby reducing cell selection or reselection by the terminal device or power consumption of the relay device, and shortening interruption time of data transmission of the terminal device.

[0085] <Example 4> The embodiment of the present invention provides a communication maintaining method, and will be described from the relay device side. The same contents as those in the third embodiment will not be described again.

[0086] 6 is a schematic diagram of an example of a communication maintaining method according to an embodiment of the present invention. As shown in FIG. 6, the method includes the following steps:

[0087] Step 601: The relay device sends a first notification message to the terminal device.

[0088] Step 602: If the relay device meets at least one of the following conditions: the relay device has not received a PC5-S release message from the terminal device, the relay device has successfully executed a Uu interface radio link failure recovery process, the relay device has successfully executed a handover process, and the relay device has completed cell selection or reselection, the relay device triggers a second notification message or sends a second notification message to the terminal device.

[0089] In an embodiment of the present invention, after sending the first notification message to the terminal device, the relay device sends the second notification message to the terminal device when at least one of the above conditions is satisfied, so that the terminal device can recover communication with the network through the relay device, reduce the cell selection or reselection by the terminal device or the power consumption of the relay device, and shorten the interruption time of data transmission of the terminal device.

[0090] In some embodiments, the cause indication value or the indication type in the first notification message is a relay device handover, a cell selection or reselection, or a Uu interface radio link failure. When a relay device has a handover, a cell selection or reselection, or a Uu RLF, the relay device may send the above-mentioned first notification message to the terminal device, and notify the terminal device of the situation by the cause indication value or the indication type in the first notification message.

[0091] In some embodiments, the cause indication value or the indication type in the second notification message is completion of the handover of the relay device, or completion of the cell selection or reselection, or recovery of the Uu interface radio link failure. If the relay device does not receive a PC5-S release message from the terminal device, and / or if the relay device successfully executes the Uu interface radio link failure recovery process, and / or if the relay device successfully executes the handover process, and / or if the relay device completes the cell selection or reselection, the relay device may send the above-mentioned second notification message to the terminal device, and notify the terminal device of the situation by the cause indication value or the indication type in the second notification message.

[0092] In the above embodiment, the PC5-S release message from the terminal device is, for example, a Disconnect Request message.

[0093] In the above embodiments, the successful execution of the Uu interface radio link failure recovery process by the relay device includes, for example, the successful execution of the RRC connection re-establishment process by the relay device (e.g., the successful execution of the random access process or the successful transmission of the RRC re-establishment complete message to the network), or the successful execution of the CHO process in the RRC connection re-establishment process (e.g., the successful execution of the random access process or the successful transmission of the RRC reconfiguration complete message to the network).

[0094] In the above embodiments, the successful execution of the handover process by the relay device includes, for example, the successful completion of the random access process or the successful sending of an RRC reconfiguration complete message to the network.

[0095] In the above embodiment, the relay device completing cell selection or reselection includes, for example, the relay device selecting or reselecting a suitable cell.

[0096] In an embodiment of the present invention, the first notification message and the second notification message may be realized by the same PC5 RRC message, for example, a NotificationMessageSidelink message, and the first notification message and the second notification message may be distinguished by different cause values ​​or indication types. The present invention is not limited thereto, and the first notification message and the second notification message may be realized by different PC5 RRC messages.

[0097] The above-mentioned embodiments are merely illustrative of the embodiments of the present invention, but the present invention is not limited thereto, and may be appropriately modified based on the above-mentioned embodiments. For example, the above-mentioned embodiments may be used alone, or one or more of them may be used in combination.

[0098] According to a method of an embodiment of the present invention, a terminal device can restore communication with a network via a relay device, thereby reducing cell selection or reselection by the terminal device or power consumption of the relay device, and shortening interruption time of data transmission of the terminal device.

[0099] <Example 5> An embodiment of the present invention provides a communication maintenance device.

[0100] 7 is a schematic diagram of an example of a communication maintenance device according to an embodiment of the present invention. The device may be, for example, a terminal device, or a component or element configured in a terminal device. The problem-solving principle of the device is similar to that of the method of the first embodiment, so that the specific implementation of the device may refer to the implementation of the method of the first embodiment, and the overlapping contents will not be described.

[0101] As shown in FIG. 7, a communication maintaining device 700 according to an embodiment of the present invention includes the following units.

[0102] The receiving unit 701 receives a first notification message sent by a relay device, in which a cause indication value or an indication type is a handover of the relay device, a cell selection or reselection, or a Uu interface radio link failure.

[0103] The processing unit 702 determines to maintain the connection with the relay device, and suspends data transmission to and from the relay device.

[0104] In some embodiments, if the terminal device is in a connected state, the processing unit 702: Suspend all radio bearers except SRB0, suspending the PC5 RLC channels corresponding to all radio bearers other than SRB0; Suspend SRB0, Suspend the PC5 RLC channel corresponding to SRB0; Resetting the MAC, and Data transmission to or from the relay device may be suspended by performing at least one of the following actions: stopping or suspending transmission of physical layer data or signaling to the relay device.

[0105] In some embodiments, when the terminal device is in an idle or inactive state, the processing unit 702: suspending SRB0 and / or the PC5 RLC corresponding to SRB0; Resetting the MAC, sending a system information request to the relay device to request an update of system information; and At least one of the following operations is performed: initiating cell selection or cell reselection, thereby suspending data transmission to and from the relay device.

[0106] In an embodiment of the present invention, the above first notification message is, for example, a PC5 RRC message.

[0107] In some embodiments, the processing unit 702 suspends data transmission to and from the relay device after determining whether to maintain the connection with the relay device, or determines whether to maintain the connection with the relay device after suspending data transmission to and from the relay device.

[0108] 8 is a schematic diagram of another example of a communication maintaining device according to an embodiment of the present invention. The device may be, for example, a relay device, or a component or element configured in a relay device. The problem solving principle of the device is similar to that of the method of the second embodiment, so that the specific implementation of the device may refer to the implementation of the method of the second embodiment, and the overlapping contents will not be described.

[0109] As shown in FIG. 8, a communication maintaining device 800 according to an embodiment of the present invention includes the following units.

[0110] The first sending unit 801 sends a first notification message to the terminal device, where the cause indication value or the indication type in the first notification message is relay device handover, cell selection or reselection, or Uu interface radio link failure.

[0111] The processing unit 802 buffers or stores signaling and / or data from the terminal device.

[0112] In some embodiments, the processing unit 802 buffering signaling and / or data from the terminal device includes the processing unit 802 buffering or storing PC5 SRAP SDUs and / or PC5 SRAP PDUs and / or PC5 RLC SDUs and / or PC5 RLC PDUs and / or PC5 MAC SDUs and / or PC5 MAC PDUs and / or PC5 physical layer data at the PC5 interface.

[0113] In some embodiments, the processing unit 802 buffering signaling and / or data from the terminal device includes the processing unit 802 buffering or storing Uu SRAP SDUs and / or Uu SRAP PDUs and / or Uu RLC SDUs and / or Uu RLC PDUs and / or Uu MAC SDUs and / or Uu MAC PDUs and / or Uu physical layer data in the Uu interface.

[0114] In an embodiment of the present invention, the above signaling and / or data is the signaling and / or data transmitted by the terminal device to the network device via the relay device.

[0115] In some embodiments, as shown in FIG. 8, the communication maintaining device 800 further includes the following units:

[0116] The second transmitting unit 803 transmits the buffered or stored signaling and / or data to the network device after handover of the relay device is completed, or after cell selection or reselection is completed, or after Uu interface RLF is restored.

[0117] In an embodiment of the present invention, the first notification message is, for example, a PC5 RRC message.

[0118] 9 is a schematic diagram of another example of a communication maintenance device according to the fifth embodiment of the present invention. The device may be, for example, a terminal device, or a component or element configured in a terminal device. The problem-solving principle of the device is similar to that of the method of the third embodiment, so that the specific implementation of the device may refer to the implementation of the method of the third embodiment, and the overlapping contents will not be described.

[0119] As shown in FIG. 9, a communication maintaining device 900 according to an embodiment of the present invention includes the following units.

[0120] The first processing unit 901 maintains a connection with the relay device after the terminal device receives a first notification message transmitted by the relay device.

[0121] The second processing unit 902 restores data transmission between the terminal device and the relay device after the terminal device receives the second notification message sent by the relay device.

[0122] In some embodiments, the cause indication value or indication type in the first notification message is a relay device handover, a cell selection or reselection, or a Uu interface radio link failure, and / or the cause indication value or indication type in the second notification message is completion of relay device handover, or completion of cell selection or reselection, or recovery of Uu interface radio link failure.

[0123] In some embodiments, the first notification message and the second notification message are the same PC5 RRC message, or are different PC5 RRC messages.

[0124] In some embodiments, the second processing unit 902 recovers the data transmission to and from the relay device by: Resuming all radio bearers except SRB0, re-establishing the PDCP of SRB2 and DRB; re-establishing the PC5 RLC channels corresponding to all radio bearers other than SRB0 or ​​re-establishing the RLC channels corresponding to all radio bearers other than SRB0; Resuming SRB1, re-establishing the PDCP of SRB1; Restarting the PC5 RLC channel corresponding to SRB1 or re-establishing the RLC for SRB1; resuming transmission to the relay device; Applying the default configuration for SRB1, sending a system information request to the relay device to request updated system information; Stopping or terminating the cell selection or reselection process; and The method includes performing at least one of the following operations: stopping or terminating the RRC connection re-establishment process.

[0125] In some embodiments, as shown in FIG. 9, the communication maintaining device 900 further includes the following units:

[0126] The third processing unit 903 starts a timer when the terminal device receives the first notification message, and stops the timer when the terminal device receives the second notification message while the timer is running.

[0127] In some embodiments, if the terminal device does not receive the second notification message during the operation of the timer, after the timer times out, the third processing unit 903: initiating an RRC connection re-establishment; Continue with the RRC connection re-establishment; Releasing the PC5 connection with the relay device; and The method performs at least one of the following operations: performing cell selection or relay selection.

[0128] In some embodiments, the value of the timer is configured or predefined by the network device.

[0129] In some embodiments, as shown in FIG. 9, the communication maintaining device 900 further includes the following units:

[0130] The fourth processing unit 904 determines whether the terminal device has not received the second notification message within a predefined period after receiving the first notification message. initiating an RRC connection re-establishment; Continue with the RRC connection re-establishment; Releasing the PC5 connection with the relay device; and The method performs at least one of the following operations: performing cell selection or relay selection.

[0131] 10 is a schematic diagram of another example of a communication maintenance device according to an embodiment of the present invention. The device may be, for example, a terminal device, or a component or element configured in a terminal device. The problem-solving principle of the device is similar to that of the method of the fourth embodiment, so that the specific implementation of the device may refer to the implementation of the method of the fourth embodiment, and the overlapping contents will not be described.

[0132] As shown in FIG. 10, a communication maintaining device 1000 according to an embodiment of the present invention includes the following units.

[0133] The transmitting unit 1001 transmits a first notification message to the terminal device.

[0134] The processing unit 1002 triggers the second notification message or sends the second notification message to the terminal device when at least one of the following conditions is met: the relay device has not received a PC5-S release message from the terminal device, the relay device has successfully executed a Uu interface radio link failure recovery process, the relay device has successfully executed a handover process, and the relay device has completed cell selection or reselection.

[0135] In some embodiments, the cause indication value or indication type in the first notification message is a relay device handover, a cell selection or reselection, or a Uu interface radio link failure, and / or the cause indication value or indication type in the second notification message is completion of relay device handover, or completion of cell selection or reselection, or recovery of Uu interface radio link failure.

[0136] In some embodiments, the first notification message and the second notification message are the same PC5 RRC message, or are different PC5 RRC messages.

[0137] Although only the components or modules related to the present invention have been described above, the present invention is not limited thereto. The communication maintenance devices 700, 800, 900, and 1000 according to the embodiments of the present invention may include other components or modules, and reference may be made to related art for specific contents of these components or modules.

[0138] 7 to 10 show only the connection relationships or signal flows between the respective components or modules as examples, but a person skilled in the art may adopt various related technologies such as bus connection. The various components or modules described above may be implemented by hardware devices such as a processor, a memory, a transmitter, a receiver, etc., but the implementation of the present invention is not limited thereto.

[0139] According to an embodiment of the present invention, data loss can be avoided, and a terminal device can restore communication with a network via a relay device, thereby reducing cell selection or reselection by the terminal device or power consumption of the relay device, and shortening interruption time of data transmission of the terminal device.

[0140] <Example 6> An embodiment of the present invention provides a communication system. Fig. 11 is a schematic diagram showing a communication system according to an embodiment of the present invention. As shown in Fig. 11, a communication system 1100 includes a terminal device 1101, a relay device 1102, and a network device 1103. For convenience of explanation, Fig. 11 has been described using only one terminal device, one relay device, and one network device as an example, but the embodiment of the present invention is not limited thereto.

[0141] In the embodiment of the present invention, the terminal device 1101, the relay device 1102 and the network device 1103 are in a UE-to-Network relay scenario.

[0142] In the embodiments of the present invention, the terminal device 1101 is configured to execute the method described in the first or third embodiment, the relay device 1102 is configured to execute the method described in the second or fourth embodiment, and the network device 1103 is configured to receive signaling and / or data transmitted by the terminal device 1101 via the relay device 1102. In the first to fourth embodiments, each method is described in detail, so the contents thereof are incorporated herein by reference and the description thereof is omitted.

[0143] The embodiment of the present invention further provides a terminal device, which may be, for example, a UE in a UE-to-Network relay, but the present invention is not limited thereto and may be other devices.

[0144] Fig. 12 is a schematic diagram of a terminal device according to an embodiment of the present invention. As shown in Fig. 12, the terminal device 1200 may include a processor 1201 and a memory 1202. The memory 1202 stores data and programs and is connected to the processor 1201. It should be noted that this figure is merely exemplary, and other types of structures may be used to supplement or replace this structure to realize communication functions or other functions.

[0145] For example, the processor 1201 may be configured to execute a program to realize the method described in the first or third embodiment.

[0146] As shown in Fig. 12, the terminal device 1200 may further include a communication module 1203, an input unit 1204, a display 1205, and a power source 1206. It is not necessary for the terminal device 1200 to include all the units shown in Fig. 12. The terminal device 1200 may further include units not shown in Fig. 12, and may refer to the prior art.

[0147] The embodiment of the present invention further provides a relay device, which may be, for example, a relay UE in a UE-to-Network relay scenario, but the present invention is not limited thereto and may be other devices.

[0148] Fig. 13 is a schematic diagram of a relay device according to an embodiment of the present invention. As shown in Fig. 13, the relay device 1300 may include a processor 1301 and a memory 1302. The memory 1302 stores data and programs and is connected to the processor 1301. It should be noted that this figure is merely exemplary, and other types of structures may be used to supplement or replace this structure to realize communication functions or other functions.

[0149] For example, the processor 1301 may be configured to execute a program to realize the method described in the second or fourth embodiment.

[0150] As shown in Fig. 13, the relay device 1300 may further include a communication module 1303, an input unit 1304, a display 1305, and a power source 1306. Note that the relay device 1300 does not need to include all the units shown in Fig. 13. The relay device 1300 may further include units not shown in Fig. 13, and may refer to the prior art.

[0151] In an embodiment of the present invention, there is further provided a computer-readable program, which, when executed on a terminal device, causes a computer to execute the method described in embodiment 1 or embodiment 3 above on the terminal device.

[0152] An embodiment of the present invention further provides a storage medium having a computer-readable program stored thereon, the program, when executed, causing a computer to execute the method described in the above embodiment 1 or embodiment 3 on a terminal device.

[0153] In an embodiment of the present invention, there is further provided a computer-readable program, which, when executed in a relay device, causes a computer to execute the method described in the above embodiment 2 or embodiment 4 in the relay device.

[0154] An embodiment of the present invention further provides a storage medium having a computer-readable program stored therein, the program, when executed, causing a computer to execute the method described in the above embodiment 2 or embodiment 4 in a relay device.

[0155] The above-mentioned apparatus and method of the present invention may be realized by hardware or by a combination of hardware and software. The present invention relates to a computer readable program which, when executed by a logic unit, causes the logic unit to realize the above-mentioned apparatus or components, or to realize the above-mentioned various methods or steps. The logic unit may be, for example, a field programmable logic unit, a microprocessor, a processor used in a computer, etc. The present invention relates to a storage medium for storing the above-mentioned program, for example, a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory, etc.

[0156] Each processing method in each device described with reference to the embodiments of the present invention may be implemented by hardware, a software module executed by a processor, or a combination of both. For example, one or more of the functional block diagrams shown in the drawings, or one or more combinations of the functional block diagrams, may correspond to each software module in a computer program flow, or each hardware module. These software modules may correspond to each step shown in the drawings. These hardware modules may be realized by implementing these software modules in hardware, for example, using a field programmable gate array (FPGA).

[0157] The software module may be located in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a mobile hard disk, a CD-ROM, or any other form of storage medium known to those skilled in the art. The storage medium may be connected to the processor so that the processor reads information from the storage medium and writes information to the storage medium, or the storage medium may be a component of the processor. The processor and the storage medium may be located in an ASIC. The software module may be stored in the memory of the mobile terminal, or in a memory card inserted in the mobile terminal. For example, if the device (e.g., a mobile terminal) uses a MEGA-SIM card or a large capacity flash memory device with a relatively large capacity, the software module may be stored in the MEGA-SIM card or the large capacity flash memory device.

[0158] One or more of the functional blocks and / or one or more combinations of functional blocks in the functional block diagrams illustrated in the drawings may be implemented with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or any suitable combination thereof to perform the functions described herein. One or more of the functional blocks and / or one or more combinations of functional blocks in the functional block diagrams illustrated in the drawings may be implemented with, for example, a combination of computing devices, such as a combination of a DSP and a microprocessor, a combination of multiple microprocessors, one or more microprocessors in combination with a DSP communication, or any other configuration.

[0159] Although the present invention has been described above with reference to specific embodiments, the above description is merely illustrative and does not limit the scope of protection of the present invention. Various modifications and changes may be made to the present invention without departing from the spirit and principles of the present invention, and these modifications and changes are also within the scope of the present invention.

[0160] Furthermore, the following supplementary notes are disclosed regarding the embodiments including the above examples. (Appendix 1) A method for maintaining communication, comprising: A step of receiving a first notification message sent by a relay device by a terminal device, where a cause indication value or an indication type in the first notification message is a relay device handover, a cell selection or reselection, or a Uu interface radio link failure; the terminal device determining to maintain a connection with the relay device and suspending data transmission between the terminal device and the relay device. (Appendix 2) The terminal device suspends data transmission between the terminal device and the relay device, When the terminal device is in a connected state, the terminal device: Suspend all radio bearers except SRB0, suspending the PC5 RLC channels corresponding to all radio bearers other than SRB0; Suspend SRB0, Suspend the PC5 RLC channel corresponding to SRB0; Resetting the MAC, and 2. The method of claim 1, comprising performing at least one operation of stopping or suspending transmission of physical layer data or signaling to the relay device. (Appendix 3) The terminal device suspends data transmission between the terminal device and the relay device, When the terminal device is in an idle or inactive state, the terminal device: suspending SRB0 and / or the PC5 RLC channel corresponding to SRB0; Resetting your MAC, sending a system information request to the relay device to request an update of system information; and 2. The method of claim 1, comprising performing at least one of the following operations: initiating cell selection or cell reselection. (Appendix 4) 4. The method of claim 1, wherein the first notification message is a PC5 RRC message. (Appendix 5) A method for maintaining communication, comprising: A step of a relay device sending a first notification message to a terminal device, where a cause indication value or an indication type in the first notification message is a relay device handover, a cell selection or reselection, or a Uu interface radio link failure; and the relay device buffering or storing signaling and / or data from the terminal device. (Appendix 6) The relay device buffering the signaling and / or data from the terminal device includes: 6. The method of claim 5, comprising the terminal device buffering or storing PC5 SRAP SDUs and / or PC5 SRAP PDUs and / or PC5 RLC SDUs and / or PC5 RLC PDUs and / or PC5 MAC SDUs and / or PC5 MAC PDUs and / or PC5 physical layer data at a PC5 interface. (Appendix 7) The relay device buffering the signaling and / or data from the terminal device includes: The method of claim 5, further comprising: the terminal device buffering or storing Uu SRAP SDUs and / or Uu SRAP PDUs and / or Uu RLC SDUs and / or Uu RLC PDUs and / or Uu MAC SDUs and / or Uu MAC PDUs and / or Uu physical layer data in a Uu interface. (Appendix 8) A method as claimed in any one of appendixes 5 to 7, wherein the signalling and / or data is signalling and / or data transmitted by the terminal device via the relay device to a network device. (Appendix 9) 9. The method of claim 8, further comprising the step of transmitting the buffered or stored signaling and / or data to the network device after handover of the relay device is completed, or after cell selection or reselection is completed, or after Uu interface RLF is restored. (Appendix 10) 8. The method of any one of claims 5 to 7, wherein the first notification message is a PC5 RRC message. (Appendix 11) A method for maintaining communication, comprising: After the terminal device receives a first notification message sent by the relay device, the terminal device maintains a connection with the relay device; and recovering data transmission between the terminal device and the relay device after the terminal device receives a second notification message sent by the relay device. (Appendix 12) The cause indication value or the indication type in the first notification message is relay device handover, cell selection or reselection, or Uu interface radio link failure; and / or The method of claim 11, wherein the cause indication value or indication type in the second notification message is completion of relay device handover, or completion of cell selection or reselection, or recovery of Uu interface radio link failure. (Appendix 13) 13. The method according to claim 11 or 12, wherein the first notification message and the second notification message are the same PC5 RRC message or different PC5 RRC messages. (Appendix 14) The terminal device recovering data transmission between the terminal device and the relay device includes: The terminal device, Resuming all radio bearers except SRB0, re-establishing the PDCP of SRB2 and DRB; re-establishing the PC5 RLC channels corresponding to all radio bearers other than SRB0 or ​​re-establishing the RLC channels corresponding to all radio bearers other than SRB0; Resuming SRB1, re-establishing the PDCP of SRB1; Restarting the PC5 RLC channel corresponding to SRB1 or re-establishing the RLC for SRB1; resuming transmission to the relay device; Applying the default configuration for SRB1, sending a system information request to the relay device to request updated system information; Stopping or terminating the cell selection or reselection process; and 13. The method of claim 11 or 12, comprising performing at least one of the following operations: stopping or terminating the RRC connection re-establishment process. (Appendix 15) starting a timer when the terminal device receives the first notification message; A method according to any one of appendixes 11 to 14, further comprising a step of the terminal device stopping the timer when the terminal device receives the second notification message while the timer is running. (Appendix 16) If the terminal device does not receive the second notification message during the operation of the timer, after the timer times out, the terminal device: initiating an RRC connection re-establishment; Continue with the RRC connection re-establishment; Releasing the PC5 connection with the relay device; and 16. The method of claim 15, further comprising performing at least one of: performing cell selection or relay selection. (Appendix 17) 16. The method of claim 15, wherein the timer value is configured by the network device or is predefined. (Appendix 18) If the terminal device does not receive the second notification message within a predefined period of time after receiving the first notification message, the terminal device: initiating an RRC connection re-establishment; Continue with the RRC connection re-establishment; Releasing the PC5 connection with the relay device; and 15. The method of any of claims 11 to 14, further comprising performing at least one of the following operations: performing cell selection or relay selection. (Appendix 19) A method for maintaining communication, comprising: A step of transmitting a first notification message from the relay device to the terminal device; The relay device has not received a PC5-S release message from the terminal device; The relay device has successfully executed a Uu interface radio link failure recovery process; the relay device has successfully performed a handover process; and and when at least one condition of the relay device completing cell selection or reselection is satisfied, the relay device triggers the second notification message or sends the second notification message to the terminal device. (Appendix 20) The cause indication value or the indication type in the first notification message is relay device handover, cell selection or reselection, or Uu interface radio link failure; and / or The method of claim 19, wherein the cause indication value or indication type in the second notification message is completion of relay device handover, or completion of cell selection or reselection, or recovery of Uu interface radio link failure. (Appendix 21) 21. The method of claim 19 or 20, wherein the first notification message and the second notification message are the same PC5 RRC message or different PC5 RRC messages. (Appendix 22) A terminal device including a memory in which a computer program is stored and a processor, the processor being configured to execute the computer program to realize a method according to any one of appendices 1 to 4 and 11 to 18. (Appendix 23) A relay device including a memory in which a computer program is stored, and a processor, the processor being configured to execute the computer program to realize a method according to any one of appendices 5 to 10 and 19 to 21. (Appendix 24) A communication system including a terminal device, a relay device, and a network device, The terminal device is configured to execute a method according to any one of appendices 1 to 4 and 11 to 18, The relay device is configured to execute a method according to any one of claims 5 to 10 and 19 to 21; The network device is configured to receive signaling and / or data transmitted by the terminal device via the relay device.

Claims

1. A communication maintenance device configured in a terminal device, A receiver for receiving a first notification message sent by a relay device, wherein a cause indication value or an indication type in the first notification message is a handover of a relay device, a cell selection or reselection, or a Uu interface radio link failure; a processor that determines to maintain a connection with the relay device and suspends data transmission to and from the relay device.

2. The processing unit suspends data transmission between the relay device and the relay device, When the terminal device is in a connected state, the processing unit suspending all radio bearers except for signaling radio bearer 0 (SRB0); suspending the PC5 interface Radio Link Control (PC5 RLC) channels corresponding to all radio bearers other than Signaling Radio Bearer 0 (SRB0); suspending signaling radio bearer 0 (SRB0); suspending a PC5 interface radio link control (PC5 RLC) channel corresponding to signaling radio bearer 0 (SRB0); Resetting the Medium Access Control (MAC); and The apparatus of claim 1 , further comprising performing at least one of the following actions: ceasing or suspending transmission of physical layer data or signaling to the relay device.

3. The processing unit suspends data transmission between the relay device and the relay device, When the terminal device is in an idle state or an inactive state, the processing unit: suspending signaling radio bearer 0 (SRB0) and / or a PC5 interface radio link control (PC5 RLC) corresponding to signaling radio bearer 0 (SRB0); Resetting the Medium Access Control (MAC); sending a system information request to the relay device to request an update of system information; and The apparatus of claim 1 , further comprising performing at least one of the following actions: initiating cell selection or cell reselection.

4. The apparatus of claim 1 , wherein the first notification message is a PC5 interface radio resource control (PC5 RRC) message.

5. The device according to claim 1 , wherein the processing unit suspends data transmission between the relay device and the device after determining whether to maintain the connection with the relay device, or determines whether to maintain the connection with the relay device and the device after suspending data transmission between the relay device and the device.

6. A communication maintenance device configured in a relay device, A first transmission unit for transmitting a first notification message to a terminal device, wherein a cause indication value or an instruction type in the first notification message is a handover of a relay device, a cell selection or reselection, or a Uu interface radio link failure; a processing unit for buffering or storing signaling and / or data from the terminal device.

7. The processing unit buffers the signaling and / or data from the terminal device, 7. The apparatus of claim 6, wherein the processing unit comprises: buffering or storing PC5 interface Sidelink Relay Adaptation Protocol Service Data Units (PC5 SRAP SDUs) and / or PC5 interface Sidelink Relay Adaptation Protocol Protocol Data Units (PC5 SRAP PDUs) and / or PC5 interface Radio Link Control Service Data Units (PC5 RLC SDUs) and / or PC5 interface Radio Link Control Protocol Data Units (PC5 RLC PDUs) and / or PC5 interface Medium Access Control Service Data Units (PC5 MAC SDUs) and / or PC5 interface Medium Access Control Protocol Data Units (PC5 MAC PDUs) and / or PC5 physical layer data at the PC5 interface.

8. The processing unit buffers the signaling and / or data from the terminal device, 7. The apparatus of claim 6, wherein the processing unit comprises buffering or storing Uu interface sidelink relay adaptation protocol service data units (Uu SRAP SDUs) and / or Uu interface sidelink relay adaptation protocol protocol data units (Uu SRAP PDUs) and / or Uu interface radio link control service data units (Uu RLC SDUs) and / or Uu interface radio link control protocol data units (Uu RLC PDUs) and / or Uu interface medium access control service data units (Uu MAC SDUs) and / or Uu interface medium access control protocol data units (Uu MAC PDUs) and / or Uu physical layer data at the Uu interface.

9. The device according to claim 6 , wherein the signaling and / or data is signaling and / or data transmitted by the terminal device via the relay device to a network device.

10. 10. The apparatus of claim 9, further comprising: a second transmitter configured to transmit the buffered or stored signaling and / or data to the network device after a handover of the relay device is completed, or after a cell selection or reselection is completed, or after a Uu interface RLF is recovered.

11. The apparatus of claim 6 , wherein the first notification message is a PC5 interface radio resource control (PC5 RRC) message.

12. A communication maintenance device configured in a terminal device, a first processing unit that maintains a connection between the terminal device and the relay device after the terminal device receives a first notification message transmitted by the relay device; a second processing unit that recovers data transmission between the terminal device and the relay device after the terminal device receives a second notification message sent by the relay device.

13. The cause indication value or the indication type in the first notification message is relay device handover, cell selection or reselection, or Uu interface radio link failure; and / or The apparatus of claim 12, wherein a cause indication value or an indication type in the second notification message is completion of relay device handover, or completion of cell selection or reselection, or recovery of Uu interface radio link failure.

14. 13. The apparatus of claim 12, wherein the first notification message and the second notification message are the same PC5 interface radio resource control (PC5 RRC) message or are different PC5 interface radio resource control (PC5 RRC) messages.

15. The second processing unit recovers data transmission to and from the relay device, The second processing unit, resuming all radio bearers except for signaling radio bearer 0 (SRB0); re-establishing a Packet Data Convergence Protocol (PDCP) for the Signaling Radio Bearer 2 (SRB2) and the Data Radio Bearer (DRB); re-opening the PC5 interface radio link control (PC5 RLC) channels corresponding to all radio bearers other than signaling radio bearer 0 (SRB0) or re-establishing the radio link control (RLC) channels corresponding to all radio bearers other than signaling radio bearer 0 (SRB0); resuming signaling radio bearer 1 (SRB1); re-establishing the PDCP for signaling radio bearer 1 (SRB1); re-establishing a PC5 interface radio link control (PC5 RLC) channel corresponding to signaling radio bearer 1 (SRB1) or re-establishing the radio link control (RLC) channel of signaling radio bearer 1 (SRB1); resuming transmission to the relay device; applying a default configuration for signaling radio bearer 1 (SRB1); sending a system information request to the relay device to request updated system information; Stopping or terminating the cell selection or reselection process; and 13. The apparatus of claim 12, further comprising performing at least one of: stopping or terminating a radio resource control (RRC) connection re-establishment process.

16. The apparatus according to claim 12, further comprising: a third processing unit that starts a timer when the terminal device receives the first notification message, and stops the timer when the terminal device receives the second notification message while the timer is running.

17. If the terminal device does not receive the second notification message during the operation of the timer, after the timer times out, the third processing unit: initiating a radio resource control (RRC) connection re-establishment; continuing the radio resource control (RRC) connection re-establishment; Releasing the PC5 connection between the relay device and the relay device; and The apparatus of claim 16 , further comprising: a first node configured to select a first node from among the first and second nodes;

18. The apparatus of claim 16 , wherein the value of the timer is configured by a network device or is predefined.

19. If the terminal device does not receive the second notification message within a predefined period of time after receiving the first notification message, initiating a radio resource control (RRC) connection re-establishment; continuing the radio resource control (RRC) connection re-establishment; Releasing the PC5 connection between the relay device and the relay device; and The apparatus of claim 12 , further comprising: a fourth processing unit configured to perform at least one of the following operations: performing cell selection or relay selection.

20. The second notification message includes: The relay device has not received a PC5-S release message from the terminal device; the relay device has successfully performed a Uu interface radio link failure recovery process; the relay device has successfully performed a handover process; and The apparatus of claim 12 , wherein the relay device is sent when the relay device satisfies at least one of the following conditions: the relay device has completed cell selection or reselection.

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