Nondestructive delivery

Abstract

Example embodiments of the present disclosure relate to apparatuses, methods, and computer-readable storage media for lossless delivery. In one method, a first device receives, from a second device or a third device, an indication that communication between the first device and a fourth device is using an indirect communication path via a fifth device; and determining whether the data packet is to be removed from the buffer based on the received indication.

Description

Technical Field

[0001] Various example embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly, to apparatus, methods, and computer-readable storage media for lossless delivery. Background Art

[0002] In current releases (Release 17 and Release 18), SL-based U2N relays are single-hop (SH) U2N relays, where a remote UE connects directly to a single UE-to-network (U2N) relay UE via the SL and uses the U2N relay UE to connect to the serving network. Lossless delivery is supported in current systems, for example, via Radio Link Control (RLC) Acknowledged Mode (AM). Lossless handover is supported in current systems, for example, referred to as "lossless handover." Summary of the Invention

[0003] In a first aspect of the present disclosure, a first device is provided. The first device includes at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the first device to at least: receive an indication from a second device or a third device that communication between the first device and a fourth device is using an indirect communication path via a fifth device; and determine, based on the received indication, whether a data packet is to be removed from a buffer.

[0004] In a second aspect of the present disclosure, a second device is provided. The second device includes: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second device to at least: transmit to a first device an indication that communication between the first device, the second device, and a fourth device is using an indirect communication path via a fifth device.

[0005] In a third aspect of the present disclosure, a third apparatus is provided. The third apparatus includes: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the third apparatus to at least: transmit to a first apparatus an indication that communications between the first apparatus, a second apparatus, and a fourth apparatus are using an indirect communication path via a fifth apparatus.

[0006] In a fourth aspect of the present disclosure, a method is provided, comprising: receiving an indication from a second device or a third device that communication between a first device and a fourth device is using an indirect communication path via a fifth device; and determining whether a data packet is to be removed from a buffer based on the received indication.

[0007] In a fifth aspect of the present disclosure, a method is provided, comprising: sending an indication to a first device that communications among the first device, a second device, and a fourth device are using an indirect communication path via a fifth device.

[0008] In a sixth aspect of the present disclosure, a method is provided, comprising: transmitting to a first device an indication that communications among the first device, a second device, and a fourth device are using an indirect communication path via a fifth device.

[0009] In a seventh aspect of the present disclosure, a first device is provided. The first device includes: a component for receiving an indication from a second device or a third device that communication between the first device and a fourth device is using an indirect communication path via a fifth device; and a component for determining whether a data packet is to be removed from a buffer based on the received indication.

[0010] In an eighth aspect of the present disclosure, a second apparatus is provided, wherein the second apparatus includes means for sending an indication to a first apparatus that communication between the first apparatus, the second apparatus, and a fourth apparatus is using an indirect communication path via a fifth apparatus.

[0011] In a ninth aspect of the present disclosure, a third apparatus is provided, wherein the third apparatus includes means for sending an indication to the first apparatus that communications among the first apparatus, the second apparatus, and the fourth apparatus are using an indirect communication path via a fifth apparatus.

[0012] In a tenth aspect of the present disclosure, a computer-readable medium is provided, wherein the computer-readable medium includes instructions stored thereon, the instructions being configured to cause a device to at least execute the method according to the fourth aspect.

[0013] In an eleventh aspect of the present disclosure, a computer-readable medium is provided, wherein the computer-readable medium includes instructions stored thereon, the instructions being configured to cause a device to at least execute the method according to the fifth aspect.

[0014] In a twelfth aspect of the present disclosure, a computer-readable medium is provided, wherein the computer-readable medium includes instructions stored thereon, the instructions being configured to cause a device to at least execute the method according to the sixth aspect.

[0015] It should be understood that the summary of the invention is not intended to identify the key features or essential features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0017] Figure 1An exemplary communication environment is shown in which example embodiments of the present disclosure may be implemented;

[0018] Figure 2 shows a signaling flow of communication according to some embodiments of the present disclosure;

[0019] Figure 3 shows a signaling flow of communication according to some embodiments of the present disclosure;

[0020] Figure 4 A flowchart illustrating a method implemented at a first device according to some example embodiments of the present disclosure is shown;

[0021] Figure 5 A flowchart illustrating a method implemented at a second device according to some example embodiments of the present disclosure is shown;

[0022] Figure 6 A flowchart illustrating a method implemented at a third device according to some example embodiments of the present disclosure is shown;

[0023] Figure 7 shows a simplified block diagram of a device suitable for implementing an example embodiment of the present disclosure; and

[0024] Figure 8 A block diagram of an example computer-readable medium is shown, according to some example embodiments of the present disclosure.

[0025] Throughout the drawings, the same or similar reference numerals refer to the same or similar elements. DETAILED DESCRIPTION

[0026] The principles of the present invention will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only and help those skilled in the art understand and implement the present disclosure without suggesting any limitation to the scope of the present disclosure. In addition to the embodiments described below, the embodiments described herein can be implemented in various ways.

[0027] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0028] References in this disclosure to "one embodiment," "an embodiment," "an example embodiment," etc., indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is considered to be within the knowledge of those skilled in the art to affect these features, structures, or characteristics in conjunction with other embodiments (whether or not explicitly described).

[0029] It should be understood that although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the exemplary embodiments, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0030] As used herein, similar expressions such as “at least one of: a list of two or more elements” and “at least one of a list of two or more elements” where a list of two or more elements is joined by “and” or “or” refer to at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0031] As used herein, unless explicitly stated, performing a step “in response to A” does not mean performing the step immediately after “A” occurs and may include one or more intermediate steps.

[0032] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the example embodiments. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms as well. It will be further understood that when used herein, the terms "comprises", "comprising", "has", "having", "includes", and / or "including" specify the presence of stated features, elements, and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0033] As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) hardware circuit implementation only (e.g., implementation only in analog and / or digital circuitry), and (b) a combination of hardware circuitry and software such as (if applicable): (i) a combination of analog and / or digital hardware circuits and software / firmware, and (ii) any portion of a hardware processor with software (including digital signal processor(s), software, and memory(s) that work together to enable a device such as a mobile phone or server to perform various functions; and (c) Hardware circuit(s) and / or processor(s), such as microprocessor(s) or portion(s) of microprocessor(s), that require software (e.g., firmware) to operate, but which may not be present when not needed for operation.

[0034] This definition of "circuitry" applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" also covers an implementation of merely a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. For example, if applicable to a particular claim element, the term "circuitry" also covers a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or networking device.

[0035] As used herein, the term "communication network" refers to a network that complies with any suitable communication standard, such as New Radio (NR), Long Term Evolution (LTE), Advanced LTE (LTE-A), Wideband Code Division Multiple Access (WCDMA), High Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. In addition, according to any suitable generation communication protocol, including but not limited to first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G) communication protocols, and / or any other protocol currently known or developed in the future, communication between terminal devices and network devices in the communication network can be performed. The embodiments of the present disclosure can be applied to various communication systems. In view of the rapid development of communications, there are of course future types of communication technologies and systems in which the present disclosure can be implemented. It should not be considered that the scope of the present disclosure is limited to the above-mentioned systems.

[0036] As used herein, the term "network device" refers to a node in a communications network through which a terminal device accesses the network and receives services. A network device may refer to a base station (BS) or access point (AP), such as a NodeB (NB), an evolved NodeB (eNodeB or eNB), a NRNB (also known as a gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), a repeater, an integrated access and backhaul (IAB) node, a low-power node (such as a femto), a piconet, a non-terrestrial network (NTN) or non-terrestrial network equipment, such as satellite network equipment, low-Earth orbit (LEO) satellites and geosynchronous orbit (GEO) satellites, aircraft network equipment, and the like, depending on the terminology and technology used. In some example embodiments, a radio access network (RAN) may be based on a split architecture. A RAN node, such as a gNB, includes a central unit (CU) and one or more distributed units (DUs). The CU may further include a control plane (CP) and one or more user planes (UPs). For example, a gNB may include a gNB-CU and one or more gNB-DUs. The gNB-CU may further include a gNB-CU-CP and one or more gNB-CU-UPs.

[0037] The term "terminal device" refers to any terminal device capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices may include, but are not limited to, mobile phones, cellular phones, smart phones, voice over IP (VoIP) phones, wireless local loop phones, tablet computers, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEEs), laptop mounted devices (LMEs), USB dongles, smart devices, wireless customer premises equipment (CPE), Internet of Things (IoT) devices, watches or other wearables, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated process chain environments), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. The terminal device may also correspond to the mobile terminal (MT) portion of an IAB node (eg, a relay node).In the following description, the terms "terminal device," "communication device," "terminal," "user equipment," and "UE" may be used interchangeably.

[0038] As used herein, the terms "resources," "transmission resources," "resource blocks," "physical resource blocks" (PRBs), "uplink resources," or "downlink resources" may refer to any resources used to perform communication (e.g., communication between a terminal device and a network device), such as resources in the time domain, resources in the frequency domain, resources in the spatial domain, resources in the code domain, or any other combination of time, frequency, space, and / or code domain resources that enable communication. Hereinafter, unless explicitly stated otherwise, resources in the frequency domain and the time domain will be used as examples of transmission resources for describing some example embodiments of the present disclosure. It should be noted that the example embodiments of the present disclosure are equally applicable to other resources in other domains.

[0039] The inter-gNB distributed unit (DU) call flow has been proposed. In the case of an inter-gNB handover (HO), the source gNB-DU communicates with the source gNB-Central Unit (CU). The target gNB-DU communicates with the target gNB-Central Unit (CU).

[0040] The gNB-CU sends a UE CONTEXT MODIFICATION REQUEST message to the source gNB-DU, which includes the generated RRCReconfiguration message and instructs the source gNB-DU to stop data transmission to the UE. The source gNB-DU also sends a Downlink Data Delivery Status (DDDS) frame to notify the gNB-CU of downlink data that was not successfully transmitted to the UE.

[0041] An example of the behavior of the gNB-CU-UP when receiving DDDS is as follows. If the Report Polling Flag is set to 1, or when an NR Packet Data Convergence Protocol (PDCP) Protocol Data Unit (PDU) with the indicated DL Report NR PDCP PDU Sequence Number (SN) has been successfully delivered, the corresponding node (i.e., the gNB-DU) shall send the DL Data Delivery Status, unless an overload condition is encountered at the corresponding node. The DL Data Delivery Status sent in response to a specific DL Report NR PDCP PDU SN shall only be sent when all PDCP PDU SNs for that DL Report NR PDCP PDU have been successfully delivered in sequence.

[0042] When the node hosting the NR PDCP entity (i.e., gNB-CU-UP) receives the DL DATA DELIVERY STATUS frame: it considers the above-mentioned desired buffer size and data rate as the amount of data to be sent from the hosting node and is allowed to remove the buffered NR PDCP PDUs of the RLC AM bearer based on the feedback of the successfully delivered NR PDCP PDUs.

[0043] In case of RLC AM, after the highest NR PDCP PDU sequence number that was successfully delivered in sequence is reported to the node hosting the NR PDCP entity, the corresponding node removes the corresponding NR PDCP PDU. For RLC Unacknowledged Mode (UM), the corresponding node may remove the corresponding NR PDCP PDU after sending it to lower layers.

[0044] In a normal system (i.e., UE is directly connected to the gNB-DU), the gNB-CU-UP may frequently use DDDS (e.g., poll the gNB-DU to send DDDS) to determine whether to remove the buffered NR PDCP PDUs.

[0045] In a Layer 2 UE-to-Network (U2N) relay system, the remote UE is not directly connected to the gNB. Instead, the remote UE connects or communicates with the gNB via a relay UE. The remote UE can also connect or communicate with the gNB via more than one relay UE, which is called multi-hop indirect communication. Communication between the remote UE and the gNB is called indirect communication via relay UEs. Solution D5 (i.e., proactive data forwarding from the source gNB to the target gNB) has been agreed upon to address DL lossless path switching.

[0046] However, this may not solve the problem of lossless path switching. The source gNB-DU can send DDDS at any time. For example, the gNB-DU can send DDDS before the source gNB-CU initiates the handover. The source gNB-CU-UP may have already discarded the buffered DL data when receiving the DDDS from the gNB-DU according to the current specification of gNB-CU-UP behavior. Therefore, the CU-UP learns too late when i2x path switching is initiated and the UE has an indirect communication path via U2N relay.

[0047] When a remote UE is connected to the gNB-CU via a relay UE, the gNB-CU-UP is unaware of the indirect path. That is, the gNB-CU-UP is unaware that communications with the remote UE are using the indirect path via the relay UE. Typically, the gNB-CU-UP may frequently poll the gNB-DU to send DDDS and use the received DDDS to remove buffered DL PDCP PDUs. Once the gNB-CU-UP polls for DDDS, the gNB-DU sends DDDS.

[0048] However, in the indirect path, the gNB-DU cannot know whether the remote UE successfully received the DL PDCP PDU because lower layer acknowledgements (e.g., Automatic Repeat Request (ARQ) ACK in the Radio Link Control (RLC) layer) may only indicate successful data delivery to the relay UE. This is different from the direct path where the UE is connected directly to the gNB-DU.

[0049] Based on DDDS, the gNB-CU-UP may incorrectly remove buffered DL PDUs that were not successfully received by the remote UE. This often results in DL PDU loss. In the event of an inter-gNB path handover, data forwarding from the source gNB to the target gNB will be affected, resulting in DL PDU loss, even when Solution D5 is applied. Furthermore, lossless data delivery or lossless path switching / handover is not possible because the DL PDUs may have been removed before the HO.

[0050] Here are some examples: Step 1: The gNB-CU-UP stores DL data #10, #11, #12, and #13 in its buffer. Step 2: The gNB-CU-UP sends DL data #10, #11, and #12 to the gNB-DU. Step 3: The gNB-DU sends DL data #10 and #11 to the relay UE and receives an RLC ACK from the relay UE. The gNB-DU considers DL data #10 and #11 to be successfully transmitted. Step 4: The gNB-DU sends a DDDS to the gNB-CU-UP to indicate that DL data #10 and #11 have been successfully transmitted. The gNB-CU-UP removes DL data #10 and #11 from its buffer. Step 5: The relay UE cannot send downlink data #10 and #11 to the remote UE due to the poor connection of PC5. Step 6: The source gNB-CU-CP initiates inter-gNB path switching. Step 7: The source gNB-CU-UP forwards only DL data #11 and #12 to the target gNB-CU-UP.

[0051] In this example, the remote UE fails to receive PDCP packets #10 and #11, but the gNB-CU-UP believes that both packets were successfully sent to the remote UE. Therefore, a method is needed to support lossless delivery before handover and further support lossless handover.

[0052] This application proposes a handover solution. In this solution, a first device receives an indication from a second or third device that communication between the first device and a fourth device is using an indirect path via a fifth device. Based on the received indication, the first device determines whether to remove a data packet from a buffer. This approach effectively supports lossless handover. Sample Environment

[0053] Figure 1An example communication environment 100 is shown in which example embodiments of the present disclosure may be implemented. The communication environment 100 includes a first device 110, a second device 115, a third device 120, a fourth device 125, and a fifth device 130.

[0054] exist Figure 1 In the embodiment, the first device 110 may include a user plane of a central unit of a network device, the second device 115 may include a distributed unit of a network device, the third device 120 may include a control plane of a central unit of a network device, the fourth device 125 may include a remote terminal device, and the fifth device 130 may include a relay terminal device.

[0055] Communications in the communication environment 100 may be implemented according to any suitable communication protocol, including but not limited to first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), fifth generation (5G), sixth generation (6G), etc. cellular communication protocols, wireless local area network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, etc., and / or any other protocol currently known or developed in the future. In addition, communications may use any suitable wireless communication technology, including but not limited to: code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplex (FDD), time division duplex (TDD), multiple input multiple output (MIMO), orthogonal frequency division multiple access (OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), and / or any other technology currently known or developed in the future. Working principles and example signaling for communication

[0056] Although features are discussed individually, it should be understood that the features discussed below may be implemented individually or in any suitable subcombination. The present disclosure is not limited in this respect.

[0057] Will refer to Figure 2 and Figure 3 Discuss the example procedure. Figure 2 and Figure 3 2 and 300 illustrate signaling flows for communications according to some embodiments of the present disclosure. For discussion purposes, reference will be made to Figure 1 The signaling flows 200 and 300 are discussed, for example, by using the first device 110 , the second device 115 , the third device 120 , and the fourth device 125 .

[0058] For better understanding, in the following, the first device 110 may include a user plane of a central unit of a network device, the second device 115 may include a distributed unit of a network device, the third device 120 may include a control plane of a central unit of a network device, the fourth device 125 may include a remote terminal device, and the fifth device 130 may include a relay terminal device.

[0059] Now refer to Figure 2 .exist Figure 2 In FIG. 2 , a connection or communication 210 has been established between the first device 110 and the fourth device 125 via the fifth device 130 (not shown) and the second device 115 .

[0060] Example operations of the first device 110 angle are discussed below.

[0061] In operation, first device 110 receives 215 an indication from second device 115 or third device 120 that communication between first device 110 and fourth device 125 is using an indirect path via fifth device 130. First device 110 determines 230 whether data packets are to be removed from the buffer based on the received indication.

[0062] In some embodiments, the first device 110 may disable use of the downlink data delivery state DDDS received from the second device 115 to remove data packets from the buffer based on the received indication.

[0063] In some embodiments, the indication may be received from the second device 115 .

[0064] In some embodiments, the first device 110 may receive 215 a DDDS frame from the second device 115 that includes the indication.

[0065] In some embodiments, the first device 110 may receive 215 the indication from the third device 120 during establishment or modification of a radio bearer associated with the fourth device 125. In another example embodiment, the radio bearer is to be established or modified to use an indirect communication path via the fifth device 130.

[0066] In some embodiments, the indication may be associated with a data tunnel established or modified between the first device 110 and the second device 115 for a radio bearer of the fourth device 125. In another example embodiment, the data tunnel transmits uplink data sent from the fourth device 125 (or downlink data sent to the fourth device 125) via the fifth device 130. For example, the data tunnel is used to transmit data of a radio bearer associated with the fourth device 125 using an indirect communication path via the fifth device 130.

[0067] In some embodiments, the first device 110 may disable polling requests for DDDS frames to be transmitted from the second device 115. In another example embodiment, the first device 110 may disable the removal of data from the buffer based on DDDS frames received from the second device 115. For example, downlink data has been transmitted from the first device 110 to the fourth device 125, but the fourth device 125 has not yet received the data; for example, the data is buffered in the fifth device 125 and awaiting transmission to the fourth device 125. The first device 110 should not remove the data from its buffer based on the DDDS frames received from the second device 115. In other words, the removal of data from the buffer based on DDDS is disabled in the first device 110.

[0068] In some embodiments, the first device 110 may determine to remove the data packet from the buffer based on the expiration of a discard timer associated with the data packet.

[0069] In some embodiments, as Figure 2 As shown, after the indirect communication path to the fourth device 125 is established, the first device 110 can transmit a request for a data status report to the fourth device 125. The first device 110 can receive the data status report from the fourth device 125. The first device 110 can remove 230 the data packet from the buffer based on the received data status report, which indicates that the fourth device 125 successfully received the data packet.

[0070] In some embodiments, as Figure 2 As shown, the first device 110 can transmit a request for a data status report to the fourth device 125 based on the amount of data packets in the buffer being equal to or greater than a threshold amount.

[0071] In some embodiments, as Figure 2 As shown, the data packets may include downlink data packets sent to the fourth device 125 using an indirect path via the fifth device 130.

[0072] Example operations of the angle of the second device 115 are discussed below.

[0073] In some embodiments, the second device 115 may send 220 to the first device 110 an indication that communications between the first device 110 , the second device 115 , and the fourth device 125 are using an indirect path via the fifth device 130 .

[0074] In some embodiments, the second device 115 may send 220 the indication to the first device 110 via a downlink data delivery status DDDS frame.

[0075] In some embodiments, as Figure 2As shown, the indication can be associated with a data tunnel between the first device 110 and the second device 115 to the fourth device 125 .

[0076] Example operations from the perspective of the third device 120 are discussed below.

[0077] In some embodiments, the third device 120 may send 225 to the first device 110 an indication that communications between the first device 110 , the second device 115 , and the fourth device 125 are using an indirect path via the fifth device 130 .

[0078] In some embodiments, the third device 120 may send 225 the indication to the first device 110 during establishment or modification of a radio bearer associated with the fourth device 125 .

[0079] In some embodiments, as Figure 2 As shown, the indication may be associated with a data tunnel established or modified between the first device 110 and the second device 115 for a radio bearer of the fourth device 125 .

[0080] Now refer to Figure 3 Example embodiments of the present disclosure provide a PDCP discard mechanism in the gNB-CU-UP 320 when F1-U traffic is associated with an indirect path (i.e., the remote UE 305 is connected to the gNB via an L2 U2N relay UE 310, or in the case of multipath with both direct and indirect paths).

[0081] In some example embodiments, based on an indication received from the gNB-CU-control plane (gNB-CU-CP 325) or from the gNB-DU 315, the gNB-CU-UP 320 may know that the UE (i.e., the remote UE 305) is using an indirect path, and the gNB-CU-UP 320 may then take the following actions.

[0082] In some example embodiments, the gNB-CU-UP 320 does not poll the gNB-DU 315 to send 335 a DDDS and / or does not use the DDDS to determine removal of buffered DL PDCP PDUs. Instead, the gNB-CU-UP 320 may use a discard timer to determine 340 removal of buffered DL PDCP PDUs or request 345 the UE 305 to send 350 a PDCP status report when, for example, the amount of data in the buffer is greater than a configured threshold.

[0083] In some example embodiments, when the gNB-CU-CP 325 may initiate establishment of a DRB associated with an indirect path for the remote UE 305, the gNB-CU-CP 325 provides an indication to inform the gNB-CU-UP 320 that a particular F1-U tunnel is associated with the indirect path.

[0084] For example, when the gNB-CU-CP 325 sends 330 an E1 Application Protocol (E1AP) UE CONTEXT MODIFICATION REQUEST message to provide the DL F1-U F-TEID to the gNB-CU-UP 320, the CP indicates that the F1-U tunnel is associated with an indirect path. Based on this indication, the gNB-CU-UP 320 can take different actions as described above.

[0085] In some example embodiments, this indication is per F1-U tunnel. This supports both a single indirect path and multiple indirect paths via the same gNB-DU 315, i.e., a data radio bearer (DRB) is established with one F1-U tunnel for the direct path and another F1-U tunnel for the indirect path. Furthermore, the gNB-CU-UP 320 may be allowed to poll / use DDDS for the direct path.

[0086] Alternatively, in some example embodiments, when the gNB-DU 315 sends 335 the DDDS, the DDDS may have a new indication indicating that the F1-U tunnel is associated with an indirect path.

[0087] In some example embodiments, the request may be via a PDCP C-PDU or via RRC signaling. In the case of RRC signaling, the gNB-CU-UP 320 may indicate the need to request 345 a PDCP status report to the gNB-CU-CP 325 via E1AP. This is applicable when the remote UE 305 has a single indirect path or multiple paths with at least one indirect path.

[0088] In some example embodiments, the gNB-CU-UP 320 may receive an indirect path indication from the gNB-CU-CP 325.

[0089] In some example embodiments, when the gNB-CU-CP 325 initiates establishment of a DRB associated with an indirect path for the remote UE 305, the gNB-CU-CP 325 may provide an indication to inform the gNB-CU-UP 320 that a particular F1-U tunnel is associated with the indirect path. As an example, when the gNB-CU-CP 325 sends 330 an E1AP UE CONTEXT MODIFICATION REQUEST message to provide the DL F1-UF tunnel endpoint identifier (TEID) to the gNB-CU-UP 320, the CP indicates that the F1-U tunnel is associated with the indirect path. Based on this indication, the gNB-CU-UP 320 may take different actions as described above.

[0090] In some example embodiments, the indication can be per F1-U tunnel. This supports a single indirect path, as well as supporting multiple indirect paths via the same gNB-DU 315, i.e., a DRB is established with one F1-U tunnel for the direct path and another F1-U tunnel for the indirect path. The gNB-CU-UP 320 is still allowed to poll / use DDDS for the direct path.

[0091] Tables 1 and 2 below show example information elements (IEs) / fields for UP parameters, where the IEs provide information related to DRBs configured in the gNB-CU-UP 320. Table 1 Table 2

[0092] In some example embodiments, the gNB-CU-UP 320 receives an indirect path indication from the gNB-DU 315.

[0093] In some example embodiments, the gNB-DU 315 knows whether the F1-U tunnel is associated with an indirect path. The gNB-CU-UP 320 may poll the DDDS as usual. When the gNB-DU 315 sends 335 the DDDS, the DDDS may include a new indication indicating that the F1-U tunnel is associated with an indirect path. Based on this indication, the gNB-CU-UP 320 may take different actions as described above.

[0094] In some example embodiments, a new cause value indicating an indirect path may be introduced. Alternatively, in some example embodiments, a new IE, a new SL DDDS frame, and other new information may be introduced / indicated.

[0095] In some example embodiments, for DL ​​DATADELIVERY STATUS (PDU Type 1), this frame format is defined to transmit feedback to allow a receiving node (ie, a node hosting a PDCP entity) to control downlink user data flow via a sending node (ie, a corresponding node).

[0096] The corresponding DL data delivery status frame is shown below. Specifically, Table 3 below shows an example of how the frame is constructed when all optional IEs (ie, those whose presence is indicated by an associated flag) are present. Table 3

[0097] In some example embodiments, the absence of such an IE changes the position of all subsequent IEs on an octet level.

[0098] In some example embodiments, all IEs defined in Table 3 above may also apply to E-UTRA PDCP, unless otherwise specified. With this understanding, every instance of NR PDCP may be replaced by E-UTRA PDCP.

[0099] In some example embodiments, the reasons are defined as follows. Description: This parameter indicates the specific event reported by the corresponding node. This information element is not applicable to E-UTRA PDCP. Value range: {0=unknown, 1=radio link interruption, 2=radio link recovery, 3=UL radio link interruption, 4=DL radio link interruption, 5=UL radio link recovery, 6=DL radio link recovery, 7=indirect path, 8-228=reserved for future value extension, 229-255= Reserved for testing purposes} Field length: 1 octet.

[0100] In some example embodiments, a PDCP status report may be triggered upon at least one of the following: The higher layer requests the PDCP entity to re-establish; Higher layers request PDCP data recovery; The upper layer requests uplink data switching; • The higher layer reconfigures the PDCP entity to release DAPS, and daps-SourceRelease is configured.

[0101] The above example process may be used to support lossless delivery (and further lossless handover) in an L2 U2N relay system and may be implemented in the gNB-DU 315 , gNB-CU-CP 325 , and gNB-CU-UP 320 . Example Method

[0102] Figure 4 FIG. 4 is a flow chart illustrating an example method 400 implemented at a first device according to some example embodiments of the present disclosure. For discussion purposes, the method 400 will be described in detail. Figure 1 110 in the perspective of the first device 110, and further by reference to Figure 2 and Figure 3 Provide a description.

[0103] At block 410 , the first device receives an indication from the second device or the third device that communications between the first device and the fourth device are using an indirect path via a fifth device.

[0104] At block 420, the first device determines whether the data packet is to be removed from the buffer based on the received indication.

[0105] In some example embodiments, based on the received indication, the first apparatus may disable use of a downlink data delivery state (DDDS) received from the second apparatus to remove data packets from the buffer.

[0106] In some example embodiments, the indication is received from the second apparatus.

[0107] In some example embodiments, the first device may receive a DDDS frame including an indication from the second device.

[0108] In some example embodiments, the first apparatus may receive an indication from the third apparatus using a communication path via the fifth apparatus during establishment or modification of a radio bearer associated with the fourth apparatus.

[0109] In some example embodiments, the indication is associated with a data tunnel established between the first apparatus and the second apparatus for a radio bearer of the fourth apparatus.

[0110] In some example embodiments, the first device may disable polling requests to prevent the second device from sending additional DDDS frames.

[0111] In some example embodiments, the first apparatus may determine that the data packet is to be removed from the buffer when a discard timer associated with the data packet has expired.

[0112] In some example embodiments, after an indirect communication path has been established for the fourth device via the fifth device, the first device sends a request for a data status report to the fourth device; the first device may receive (350) the data status report from the fourth device; and the first device may remove the data packet from the buffer based on the received data status report indicating that the data packet was successfully received by the fourth device.

[0113] In some example embodiments, the first device may send a request for a data status report to the fourth device based on the amount of data packets in the buffer being equal to or greater than a threshold amount.

[0114] In some example embodiments, the data packet comprises a downlink data packet sent to the fourth apparatus using an indirect path via the fifth apparatus.

[0115] In some example embodiments, the first device comprises a user plane of a central unit of the network device, the second device comprises a distributed unit of the network device, the third device comprises a control plane of the central unit of the network device, the fourth device comprises a remote terminal device, and the fifth device comprises a relay terminal device.

[0116] Figure 5 A flowchart of an example method 500 implemented at a second device according to some example embodiments of the present disclosure is shown. For discussion purposes, Figure 1 The method 500 is described from the perspective of the second device 120 in FIG. Figure 2 and Figure 3 The method 500 is further described.

[0117] At block 510 , the second device sends an indication to the first device that communications between the first device and the fourth device are using an indirect path via a fifth device.

[0118] In some example embodiments, the second apparatus sends the indication to the first apparatus via a Downlink Data Delivery Status (DDDS) frame.

[0119] In some example embodiments, the indication is associated with a data tunnel between the first device and the second device to the fourth device.

[0120] Figure 6 FIG. 6 is a flow chart illustrating an example method 600 implemented at a third device according to some example embodiments of the present disclosure. For discussion purposes, the method 600 will be described in detail. Figure 1 The third device 130 is described from the perspective of FIG. 1 , and further by reference to FIG. Figure 2 and Figure 3 To describe.

[0121] At block 610 , the third device sends an indication to the first device that communications between the first device and the fourth device are using an indirect path via a fifth device.

[0122] In some example embodiments, during establishment or modification of a radio bearer associated with the fourth apparatus, the third apparatus may send an indication to the first apparatus using an indirect communication path via the fifth apparatus.

[0123] In some example embodiments, the indication is associated with a data tunnel established or modified between the first apparatus and the second apparatus for a radio bearer of the fourth apparatus. Example devices, apparatus, and media

[0124] In some example embodiments, a first device (eg, Figure 1 The first device 110 in the embodiment may include a component for performing the corresponding operation of the method 400. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module. The first device may be implemented as or included in Figure 1 In the first device 110.

[0125] In some example embodiments, the first device includes: means for receiving an indication from a second device or a third device that communication between the first device and a fourth device is using an indirect communication path via a fifth device; and means for determining whether the data packet is to be removed from the buffer based on the received indication.

[0126] In some example embodiments, the first apparatus further comprises means for performing the method 400 or other operations in some example embodiments of the first apparatus 110. In some example embodiments, the means comprises: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the execution of the first apparatus.

[0127] In some example embodiments, a second device (eg, Figure 1 The second device 115 in the method 500 may include a device for performing the corresponding operation of the method 500. The device may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module. The second device may be implemented as or included in Figure 1 In the second device 120.

[0128] In some example embodiments, the second apparatus comprises means for sending an indication to the first apparatus that communications between the first apparatus, the second apparatus, and the fourth apparatus are using an indirect communication path via the fifth apparatus.

[0129] In some example embodiments, the second apparatus further comprises means for performing the method 500 or other operations of some example embodiments of the second apparatus 115. In some example embodiments, the means comprises: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the execution of the second apparatus.

[0130] In some example embodiments, a third device (e.g., Figure 1 The third device 120 in the embodiment may include a device for performing the corresponding operation of method 600. The component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module. The third device may be implemented as or included in Figure 1 In the third device 120.

[0131] In some example embodiments, the third apparatus comprises means for sending an indication to the first apparatus that communications between the first apparatus, the second apparatus, and the fourth apparatus are using an indirect communication path via a fifth apparatus.

[0132] In some example embodiments, the third apparatus further comprises means for performing the method 600 or other operations of some example embodiments of the third apparatus 120. In some example embodiments, the means comprises: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the third apparatus to perform the operations.

[0133] Figure 7 is a simplified block diagram of a device 700 suitable for implementing an example embodiment of the present disclosure. The device 700 may be provided to implement a communication device, such as Figure 1 As shown in FIG, the apparatus 700 includes one or more processors 710, one or more memories 720 coupled to the processors 710, and one or more communication modules 740 coupled to the processors 710.

[0134] The communication module 740 is configured for bidirectional communication. The communication module 740 has one or more communication interfaces to facilitate communication with one or more other modules or devices. A communication interface may represent any interface necessary to communicate with other network elements. In some example embodiments, the communication module 740 may include at least one antenna.

[0135] Processor 710 may be of any type suitable for the local technology network and may include one or more of the following: a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture, as non-limiting examples. Device 700 may have multiple processors, such as application specific integrated circuit chips, that are time-slave to a clock that synchronizes a main processor.

[0136] The memory 720 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 724, electrically programmable read-only memory (EPROM), flash memory, hard disks, compact disks (CDs), digital video disks (DVDs), optical disks, laser disks, and other magnetic and / or optical memories. Examples of volatile memories include, but are not limited to, random access memory (RAM) 722 and other volatile memories that do not persist during a power outage.

[0137] The computer program 730 includes computer-executable instructions executed by the associated processor 710. The instructions of the program 730 may include instructions for performing the operations / actions of some example embodiments of the present disclosure. The program 730 may be stored in a memory (e.g., ROM 724). The processor 710 may perform any suitable actions and processes by loading the program 730 into the RAM 722.

[0138] The exemplary embodiments of the present disclosure may be implemented by the program 730 so that the device 700 may execute the following steps: Figures 2 to 6 Any process of the present disclosure discussed. Example embodiments of the present disclosure may also be implemented by hardware or a combination of software and hardware.

[0139] In some example embodiments, the program 730 may be tangibly embodied in a computer-readable medium that may be included in the device 700 (such as in the memory 720) or in other storage devices accessible by the device 700. The device 700 may load the program 730 from the computer-readable medium to the RAM 722 for execution. In some example embodiments, the computer-readable medium may include any type of non-transitory storage medium, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. The term "non-transitory" as used herein refers to the limitation of the medium itself (i.e., tangible, not a signal), as opposed to the limitation of data storage persistence (e.g., RAM versus ROM).

[0140] Figure 8 An example of a computer readable medium 800 is shown, which may be in the form of a CD, DVD, or other optical storage disc.The computer readable medium 800 has the program 730 stored thereon.

[0141] In general, various embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, and other aspects may be implemented in firmware or software, which may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flow charts, or using some other graphical representation, it should be understood that, as non-limiting examples, the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general-purpose hardware or a controller or other computing device, or some combination thereof.

[0142] Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer-readable medium (such as a non-volatile computer-readable medium). The computer program product includes computer-executable instructions, such as those included in a program module, that are executed in a device on a target physical or virtual processor to perform any of the methods described above. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The functionality of the program modules can be combined or split between program modules as needed in different embodiments. The machine-executable instructions for the program modules can be executed in a local or distributed device. In a distributed device, the program modules can be located in local and remote storage media.

[0143] The program code for performing the method of the present disclosure can be written in any combination of one or more programming languages. The program code can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device so that the program code, when executed by the processor or controller, causes the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine, partially on a remote machine, or entirely on a remote machine or server.

[0144] In the context of the present disclosure, computer program codes or related data may be carried by any suitable carrier to enable a device, apparatus or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, etc.

[0145] Computer readable medium can be a computer readable signal medium or a computer readable storage medium.Computer readable medium can include but is not limited to electronic, magnetic, optical, electromagnetic, infrared or semiconductor system, device or device or any suitable combination of the foregoing.More specific examples of computer readable storage medium will include an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device or any suitable combination of the foregoing.

[0146] Further, although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all of the operations described be performed, in order to achieve the desired result. In some cases, multitasking and parallel processing can be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be interpreted as limitations on the scope of this disclosure, but rather as descriptions of features that may be specific to a particular embodiment. Unless expressly stated otherwise, certain features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, unless expressly stated otherwise, the different features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable subcombination.

[0147] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Instead, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A first device for communication, comprising: means for receiving an indication from a second device or a third device that communications between the first device and a fourth device are using an indirect communications path via a fifth device; as well as Means for determining whether data packets are to be removed from a buffer based on said received indication.

2. The first device according to claim 1, further comprising: Means for disabling, based on the received indication, removal of the data packets from the buffer using a downlink data delivery status DDDS received from the second device.

3. The first device according to claim 1 or 2, wherein the indication is received from the second device.

4. The first device according to claim 3, wherein the first device is configured to: A DDDS frame including the indication is received from the second device.

5. The first device according to claim 1, wherein the first device is caused to: The indication is received from the third device using the indirect communication path via the fifth device during establishment or modification of a radio bearer associated with the fourth device. 6 . The first device according to claim 1 , wherein the indication is associated with a data tunnel established between the first device and the second device for a radio bearer of the fourth device.

7. The first device according to any one of claims 1 to 2, further comprising: Means for disabling polling requests for further DDDS frames from being sent by the second device.

8. The first device according to any one of claims 1 to 2, wherein the first device is configured to: Based on expiration of a discard timer associated with the data packet, it is determined that the data packet is to be removed from the buffer.

9. The first device according to any one of claims 1 to 2, further comprising: means for sending a request for a data status report to the fourth device after establishing the indirect communication path for the fourth device; means for receiving the data status report from the fourth device; as well as means for removing the data packet from the buffer based on the received data status report indicating that the data packet was successfully received by the fourth device.

10. The first device according to claim 9, further comprising: means for sending the request for the data status report to the fourth device based on the amount of data packets in the buffer being equal to or greater than a threshold amount.

11. The first device according to any one of claims 1 to 2, wherein the data packet comprises a downlink data packet sent to the fourth device using the indirect communication path via the fifth device.

12. A first device according to any one of claims 1 to 2, wherein the first device includes a user plane of a central unit of a network device, the second device includes a distributed unit of the network device, the third device includes a control plane of the central unit of the network device, the fourth device includes a remote terminal device, and the fifth device includes a relay terminal device.

13. A second device for communication, comprising: Means for sending an indication to a first device that communications between the first device and a fourth device are using an indirect communications path via a fifth device.

14. The second device according to claim 13, further comprising: Means for sending the indication to the first device via a downlink data delivery status DDDS frame. 15 . The second device according to claim 13 , wherein the indication is associated with a data tunnel between the first device and the second device to the fourth device.

16. A third device for communication, comprising: Means for sending an indication to a first device that communications between the first device and a fourth device are using an indirect communications path via a fifth device.

17. The third device according to claim 16, wherein the third device is configured to: The indication is sent to the first apparatus during establishment or modification of a radio bearer associated with the fourth apparatus. 18 . The third device according to claim 16 , wherein the indication is associated with a data tunnel established between the first device and a second device for a radio bearer of the fourth device.

19. A method for communication, comprising: receiving, at a first device, from a second device or a third device, an indication that communications between the first device and a fourth device are using an indirect communications path via a fifth device; as well as Based on the received indication, it is determined whether the data packet is to be removed from the buffer.

20. A method for communication, comprising: An indication is sent to the first device that communications between the first device and a fourth device are using an indirect communications path via a fifth device.

21. A method for communication, comprising: An indication is sent to the first device that communications between the first device and a fourth device are using an indirect communications path via a fifth device.

Images