Method and apparatus for supporting dynamic handover of secondary LCH for PDU set transmission

Abstract

The invention relates to a method and apparatus for supporting dynamic switching of secondary logical channels (LCHs) for protocol data unit (PDU) set transmission. One embodiment of the present disclosure provides a user equipment (UE) comprising: a transceiver; and a processor coupled with the transceiver and configured to: receive, via the transceiver, a secondary logical channel (LCH) activation indication from a base station (BS) for activating a secondary LCH of a data radio bearer (DRB); and in response to receiving the secondary LCH activation indication from the BS: activating the secondary LCH of the DRB; and after activating the secondary LCH of the DRB, routing a Packet Data Convergence Protocol (PDCP) PDU of a Protocol Data Unit (PDU) set through the secondary LCH of the DRB.

Description

Technical Field

[0001] The present disclosure relates to wireless communication, and in particular, to methods and apparatuses for supporting dynamic switching of a secondary logical channel (LCH) for protocol data unit (PDU) set transmission. Background Art

[0002] PDU sets and PDU set quality of service (QoS) characteristics may be introduced for extended reality (XR) services, which may include augmented reality (AR) and virtual reality (VR) as well as cloud gaming (CG), and may present new and promising categories of connected devices, applications, and services.

[0003] There are different types of PDU sets, e.g., important PDU sets and unimportant PDU sets. Both types of PDU sets can be transmitted using the same LCH or different LCHs. Therefore, it is advantageous to provide a solution for supporting dynamic switching of separate LCHs for PDU set transmission. Summary of the Invention

[0004] An embodiment of the present disclosure provides a user equipment (UE) comprising: a transceiver; and a processor coupled to the transceiver and configured to: receive, via the transceiver, a secondary LCH activation indication for activating a secondary logical channel (LCH) of a data radio bearer (DRB) from a base station (BS); and in response to receiving the secondary LCH activation indication from the BS: activate the secondary LCH of the DRB; and after activating the secondary LCH of the DRB, route packet data convergence protocol (PDCP) PDUs of a PDU set through the secondary LCH of the DRB.

[0005] In some embodiments, the secondary LCH activation indication is received by a medium access control control element (MAC CE) or a PDCP control PDU of the UE.

[0006] In some embodiments, the processor is further configured to: receive a radio resource control (RRC) message comprising at least one of: a second indication indicating whether the DRB is configured with a primary LCH and the secondary LCH; a third indication indicating whether the LCH is a primary LCH or a secondary LCH; an association between a type of PDU set and the LCH; or a default activation or deactivation state of the secondary LCH.

[0007] In some embodiments, the association indication indicates that a type of PDU set having a second priority is to be associated with the secondary LCH, or indicates that both a type of PDU set having a first priority and a type of PDU set having a second priority are to be associated with the primary LCH and the secondary LCH, respectively.

[0008] In some embodiments, the processor is further configured to perform one of the following: when the type of a first set of PDUs has a first priority, route all PDCP PDUs in the first set of PDUs to the primary LCH; and when the type of a second set of PDUs has a second priority, where the second priority has a lower priority than the first priority, route all PDCP PDUs in the second set of PDUs to the secondary LCH.

[0009] In some embodiments, when there are remaining PDCP PDUs of a set of PDUs having a second priority to be transmitted using the primary LCH, the processor is further configured to perform one of the following: route all PDCP PDUs of the set of PDUs having the second priority to the secondary LCH; route the next set of PDUs having the second priority to the secondary LCH; or route the remaining PDCP PDUs of the set of PDUs having the second priority to the secondary LCH.

[0010] In some embodiments, the processor is further configured to: receive, via the transceiver, a secondary LCH deactivation indication from the BS for deactivating the secondary LCH of the DRB; deactivate the secondary LCH of the DRB in response to receiving the secondary LCH deactivation indication from the BS; and route PDCP PDUs of the set of PDUs via the primary LCH.

[0011] In some embodiments, the processor is further configured to: receive, via the transceiver, a secondary LCH deactivation indication from the BS for deactivating the secondary LCH of the DRB, and there are remaining PDCP PDUs of a set of PDUs having a second priority to be transmitted using the secondary LCH, and perform one of the following in response to receiving the secondary LCH deactivation indication from the BS: route all PDCP PDUs of the set of PDUs having the second priority to the primary LCH; route the next set of PDUs having the second priority to the primary LCH; or route the remaining PDCP PDUs of the set of PDUs having the second priority to the primary LCH.

[0012] In some embodiments, the secondary LCH activation indication includes an identifier of a reference PDCP PDU or an identifier of a reference set of PDUs, and the processor is further configured to: activate the secondary LCH after transmitting the reference PDCP PDU or the reference set of PDUs.

[0013] In some embodiments, the secondary LCH activation indication includes an identifier of a reference PDCP PDU or an identifier of a reference PDU set, and the processor is further configured to: deactivate the secondary LCH after transmitting the reference PDCP PDU or the reference PDU set.

[0014] Another embodiment of the present disclosure provides a distributed unit (DU) comprising: a transceiver; and a processor coupled to the transceiver and configured to: determine a secondary LCH activation indication for activating a DRB or a secondary LCH of a secondary tunnel; and transmit the secondary LCH activation indication via the transceiver.

[0015] In some embodiments, the secondary LCH activation indication is transmitted to a UE and carried by a MAC CE or a PDCP control PDU.

[0016] In some embodiments, the secondary LCH activation indication is transmitted to a CU and is included in F1 signaling or an F1 user plane protocol.

[0017] In some embodiments, the secondary LCH deactivation indication includes an identifier of a reference PDCP PDU or an identifier of a reference PDU set.

[0018] In some embodiments, the processor is further configured to perform one of the following: determine a secondary LCH deactivation indication for deactivating the DRB or the secondary LCH of the secondary tunnel; and transmit the secondary LCH deactivation indication via the transceiver.

[0019] Yet another embodiment of the present disclosure provides a central unit (CU) comprising: a transceiver; and a processor coupled to the transceiver and configured to: activate a secondary tunnel; and after activating the secondary tunnel, route PDCP PDUs of a PDU set through the secondary tunnel.

[0020] In some embodiments, the processor is further configured to perform one of the following: route all PDCP PDUs in the first PDU set to the primary tunnel when the type of the first PDU set has a first priority; and route all PDCP PDUs in the second PDU set to the secondary tunnel when the type of the second PDU set has a second priority, where the second priority is lower than the first priority.

[0021] In some embodiments, in a case where there are remaining PDCP PDUs of a PDU set with a second priority to be transmitted using the primary tunnel, the processor is further configured to perform one of the following: route all PDCP PDUs of the PDU set with the second priority to the secondary tunnel; route the next PDU set with the second priority to the secondary tunnel; or route the remaining PDCP PDUs of the PDU set with the second priority to the secondary tunnel.

[0022] In some embodiments, the processor is further configured to: deactivate the secondary tunnel; and in response to deactivating the secondary tunnel, deactivate the secondary tunnel; and route the PDCP PDUs of the PDU set through the primary tunnel.

[0023] In some embodiments, the processor is further configured to: deactivate the secondary tunnel, and in a case where there are remaining PDCP PDUs of a PDU set with a second priority to be transmitted using the secondary tunnel; after deactivating the secondary tunnel, perform one of the following: route all PDCP PDUs of the PDU set with the second priority to the primary tunnel; route the next PDU set with the second priority to the primary tunnel; or route the remaining PDCP PDUs of the PDU set with the second priority to the primary tunnel.

[0024] In some embodiments, determine an identifier of a reference PDCP PDU or an identifier of a reference PDU set, and the processor is further configured to: activate the secondary tunnel after transmitting the reference PDCP PDU or the reference PDU set.

[0025] In some embodiments, determine an identifier of a reference PDCP PDU or an identifier of a reference PDU set, and the processor is further configured to: deactivate the secondary tunnel after transmitting the reference PDCP PDU or the reference PDU set.

[0026] Another embodiment of the present disclosure provides a method performed by a UE, which includes: receiving, from a BS, a secondary LCH activation indication for activating a secondary LCH of a DRB; and in response to receiving the secondary LCH activation indication, activating the secondary LCH of the DRB; and after activating the secondary LCH of the DRB, routing PDU set PDCU PDUs through the secondary LCH of the DRB.

[0027] Another embodiment of the present disclosure provides a method performed by a DU, which includes: determining a secondary LCH activation indication for activating a secondary LCH or a secondary tunnel of a DRB; and transmitting the secondary LCH activation indication.

[0028] Another embodiment of the present disclosure provides a method executed by a CU, which includes: activating a secondary tunnel; and after activating the secondary tunnel, routing PDCU PDUs of a PDU set through the secondary tunnel. Description of the Drawings

[0029] To describe the manner in which the advantages and features of the present application can be obtained, a description of the present application is presented by referring to specific embodiments of the present application illustrated in the drawings. These drawings only depict example embodiments of the present application and should not be considered as limiting its scope.

[0030] Figure 1 Schematic diagram illustrating a wireless communication system according to some embodiments of the present disclosure.

[0031] Figure 2 Illustration of a DRB according to some embodiments of the present disclosure.

[0032] Figure 3 Flowchart illustrating dynamic switching of a secondary LCH for supporting PDU set transmission according to some embodiments of the present disclosure.

[0033] Figure 4 Illustration of a secondary LCH activation indication MAC CE or a secondary LCH deactivation indication MAC CE according to some embodiments of the present disclosure.

[0034] Figure 5 Illustration of the transmission of a PDU set of a DRB according to some embodiments of the present disclosure.

[0035] Figure 6 Flowchart illustrating dynamic switching of a secondary LCH for supporting PDU set transmission according to some embodiments of the present disclosure.

[0036] Figure 7 Flowchart illustrating dynamic switching of a secondary LCH or a secondary tunnel for supporting PDU set transmission according to some embodiments of the present disclosure.

[0037] Figure 8 Flowchart illustrating dynamic switching of a secondary LCH or a secondary tunnel for supporting PDU set transmission according to some embodiments of the present disclosure.

[0038] Figure 9 Illustration of a method executed by a UE according to some embodiments of the present disclosure.

[0039] Figure 10 Illustration of a method executed by a DU according to some embodiments of the present disclosure.

[0040] Figure 11 Illustration of a method executed by a CU according to some embodiments of the present disclosure.

[0041] Figure 12 Simplified block diagram of a device according to some embodiments of the present disclosure. Detailed implementation

[0042] The detailed description of the drawings is intended as a description of the currently preferred embodiments of the present invention and is not intended to represent the only form in which the present invention can be practiced. It should be understood that the same or equivalent functions can be accomplished by different embodiments that are intended to be covered within the spirit and scope of the present invention.

[0043] Although operations are depicted in the figures in a particular order, those skilled in the art will readily recognize that such operations need not be performed in the particular order shown or in a sequential order, or that all of the illustrated operations need to be performed to achieve the desired result; one or more operations may sometimes be skipped. Additionally, the figures may schematically depict one or more example processes in the form of a flowchart. However, other operations not depicted may be incorporated into the example processes schematically illustrated. For example, one or more additional operations may be performed before, after, concurrently with, or between any of the illustrated operations. In some cases, multitasking and parallel processing may be advantageous.

[0044] Reference will now be made in detail to some embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. For the sake of facilitating understanding, embodiments are provided in a specific network architecture and new service scenarios, such as cellular telephone networks, time division multiple access (TDMA)-based networks, code division multiple access (CDMA)-based networks, orthogonal frequency division multiple access (OFDMA)-based networks, LTE networks, 3rd Generation Partnership Project (3GPP)-based networks, LTE, advanced LTE (LTE-A), 3GPP 4G, 3GPP 5G NR, 3GPP Release 16 and later versions, satellite communication networks, high altitude platform networks, and so on. After careful consideration, as the network architecture and new service scenarios evolve, all embodiments in the present disclosure are also applicable to similar technical problems; moreover, the terms cited in the present disclosure may change, which should not affect the principles of the present disclosure.

[0045] Figure 1 Schematic diagram of a wireless communication system according to some embodiments of the present disclosure.

[0046] Figure 1 The wireless communication system in... includes a CU (e.g., CU 104), a UE (e.g., UE 101), and some DUs (e.g., DU 102A and DU 102B). DU 102A and DU 102B are controlled by CU 104 and serve UEs within cell #1 and cell #2, respectively. Even in Figure 1There is only one UE and two DUs in [the system], but those skilled in the art should recognize that any number of UEs and DUs can be included in a wireless communication system.

[0047] UE 101 may include a computing device, such as a desktop computer, laptop computer, personal digital assistant (PDA), tablet computer, smart TV (e.g., a TV connected to the Internet), set-top box, game console, security system (including security cameras), in-vehicle computer, network device (e.g., router, switch, modem), etc. According to an embodiment of the present disclosure, UE 101 may include a portable wireless communication device, smartphone, cellular phone, flip phone, device with a subscriber identity module, personal computer, pager, or any other device capable of sending and receiving communication signals over a wireless network. In some embodiments, UE 101 includes a wearable device, such as a smartwatch, fitness bracelet, optical head-mounted display, etc. Additionally, UE 101 may be referred to as a subscriber unit, mobile device, mobile station, user, terminal, mobile terminal, wireless terminal, fixed terminal, subscriber station, user terminal, device, or other terms used in the art.

[0048] DUs 102A and 102B may be distributed throughout a geographical area. In certain embodiments, a DU may also be referred to as an access node, access point, access terminal, base, base station, macrocell, Node-B, evolved Node B (eNB), gNB, home Node-B, relay node, device, or any other term used in the art. DUs 102A and 102B are generally part of a radio access network that may include one or more controllers communicatively coupled to one or more corresponding base stations.

[0049] CU 104 may be distributed throughout a geographical area and may control DUs 102A and 102B. In certain embodiments, a CU may also be referred to as an access node, access point, access terminal, base, base station, macrocell, Node-B, evolved Node B (eNB), gNB, home Node-B, relay node, device, or any other term used in the art.

[0050] The wireless communication system is compatible with any type of network capable of sending and receiving wireless communication signals. For example, the wireless communication system is compatible with a wireless communication network, cellular phone network, TDMA-based network, CDMA-based network, OFDMA-based network, Long Term Evolution (LTE) network, 3GPP-based network, 3GPP 5G network, satellite communication network, high altitude platform network, and / or other communication networks.

[0051] In one embodiment, the wireless communication system is compatible with NR of the 3GPP protocol, where transmission can be performed using an OFDM modulation scheme. More generally, the wireless communication system can implement some other open or proprietary communication protocols, such as WiMAX and other protocols.

[0052] In other embodiments, the transmission can be performed using other communication protocols (such as the IEEE 802.11 series of wireless communication protocols). Additionally, in some embodiments, the transmission can be performed on licensed spectrum, while in other embodiments, the transmission can be performed on unlicensed spectrum. The present disclosure is not intended to be limited to embodiments of any particular wireless communication system architecture or protocol. In another embodiment, the transmission can be performed using the 3GPP 5G protocol.

[0053] The PDU set can have different priorities, such as a PDU set with a higher priority or a lower priority; the PDU set can have different types, such as an important PDU set or an unimportant PDU set. In the following of the present disclosure, the solution is described using PDU sets with different priorities, and those skilled in the art can understand that the PDU set with different priorities can include an important PDU set or an unimportant PDU set; or PDU set type 1, PDU set type 2, etc.

[0054] In some embodiments, the application layer requires all the PDUs in the PDU set to use the corresponding information unit. In other embodiments, when some of the PDUs in the PDU set are lost, the application layer can still recover part or all of the information unit.

[0055] The PDU set can be composed of one or more PDUs carrying the payload of an information unit generated at the application level (e.g., a frame or a video segment for the XRM service). In some embodiments, the application layer requires all the PDUs in the PDU set to use the corresponding information unit. In some other embodiments, when some of the PDUs in the PDU set are lost, the application layer can still recover all the information units.

[0056] The PDU set can carry different contents, such as I-frames, B-frames, or P-frames, slices or tiles within I-frames, B-frames, or P-frames, etc. The present disclosure proposes to differently handle different PDU sets with different priorities, for example, by differently processing the PDUs (i.e., packets) belonging to the PDU set with a lower priority (i.e., the less important PDU set) to reduce resource waste.

[0057] To support the reordering function, different types of PDU sets can be mapped to one DRB. On the other hand, for handling the different importance of different types of PDU sets, one DRB can be configured with at least two RLC entities, and the corresponding LCHs can have different priorities. Then the DRB is separated into at least two corresponding LCHs.

[0058] Figure 2 Describe the DRB according to some embodiments of the present disclosure.

[0059] In Figure 2 there are N PDU sets mapped to one DRB, such as PDU set 1, PDU set 2, ..., PDU set N, where N is an integer equal to or greater than 2. PDU set 1 may have a priority value of 1; PDU set 2 may have a priority value of 2; ...; PDU set N may have a priority value of N.

[0060] The DRB may be configured with M RLC entities, such as RLC 1, RLC 2, ..., RLC M, each RLC entity corresponding to an LCH, where M is an integer equal to or greater than 2. RLC 1 may have a priority value of 1; RLC 2 may have a priority value of 2; ...; RLC M may have a priority value of M. Correspondingly, LCH 1 may have a priority value of 1; LCH 2 may have a priority value of 2; ...; LCH M may have a priority value of M.

[0061] In some embodiments, M may be equal to N, and each RLC entity or each logical channel may correspond to one type of PDU set based on the corresponding priority. In some other embodiments, M may not be equal to N, and each RLC entity or each logical channel may correspond to one or more types of PDU sets, or vice versa.

[0062] In some embodiments, both the value of M and the value of N are 2. In this case, the PDU set with a higher priority may also be referred to as an important PDU set or PDU set type 1, and the PDU set with a lower priority may also be referred to as an unimportant PDU set or PDU set type 2. The LCH with a higher priority may also be referred to as the main LCH or main branch, and the LCH with a lower priority may also be referred to as the secondary LCH or secondary branch.

[0063] The DRB may have a common service data adaptation protocol (SDAP) layer and a common packet data convergence protocol (PDCP) layer. The DRB may be served by a single DU or a single gNB (such as Figure 1 the DU 102A shown in

[0064] However, the transmission of different sets of PDUs with different priorities may have some problems. One problem may be that even when the network is not congested, the set of PDUs with lower priority may still be blocked or delayed. The set of PDUs with higher priority may use the LCH with higher priority (e.g., the primary LCH) and may always be transmitted before the set of PDUs with lower priority using the LCH with lower priority (e.g., the secondary LCH). In some embodiments, an important set of PDUs that arrives later on the primary LCH may always be transmitted before an unimportant set of PDUs that arrives earlier on the secondary LCH, which may cause an unnecessary delay in the transmission of the earlier-arriving unimportant set of PDUs (e.g., P-frames). In other words, some transmissions of unimportant sets of PDUs using the secondary LCH may be blocked. Therefore, the user experience may be affected.

[0065] The present disclosure proposes some solutions to solve this problem. In the following of the present disclosure, two LCHs (or two branches, corresponding to two RLC entities) and two types of sets of PDUs are used to describe the solutions, and those skilled in the art know that the solutions in the present disclosure can also be applied to other numbers of LCHs or other numbers of types of sets of PDUs.

[0066] More specifically, the present disclosure introduces an indication for the secondary LCH that can activate or deactivate the DRB. The indication can activate or deactivate the secondary branch between the UE and the DU or the secondary F1-U tunnel between the CU and the DU. This indication can be referred to as a secondary LCH activation indication, a secondary LCH deactivation indication, a split LCH activation indication, a split LCH deactivation indication, etc. In the following of the present disclosure, the expressions "secondary LCH activation indication" and "secondary LCH deactivation indication" are used.

[0067] When network congestion occurs, the secondary LCH can be activated, and then the set of PDUs with higher priority (e.g., the set of PDUs of I-frames) will be transmitted through the primary LCH, while the set of PDUs with lower priority (e.g., the set of PDUs of P-frames) will be transmitted through the secondary LCH. Due to the lack of radio resources and logical channel priority sorting (LCP) handling, the set of PDUs of P-frames may be discarded. When the network congestion is alleviated, the secondary LCH is deactivated; both the set of PDUs of I-frames and the set of PDUs of P-frames can be transmitted through the primary LCH.

[0068] Solution 1:

[0069] Solution 1 focuses on the UL data transmission between the UE and the BS. When UL congestion occurs, the BS can send a secondary LCH activation indication to the UE, and the secondary LCH activation indication can instruct the UE to activate the secondary LCH, and separate the important PDU set and the unimportant PDU set into different RLC entities or LCHs. After receiving the secondary LCH activation indication, the UE can activate the secondary LCH, and the PDCP layer of the UE can deliver the important PDU set and the unimportant PDU set to the corresponding RLC entity or LCH. When the UL congestion is alleviated, the BS can send a secondary LCH deactivation indication to the UE, and the UE can deactivate the secondary LCH, and deliver all the PDU sets to the primary RLC entity or LCH. In some other cases, the BS can instruct the UE to activate or deactivate more LCHs or more RLC entities, and the UE can deliver the PDU sets to the corresponding RLC entity or LCH in a similar manner.

[0070] Figure 3 A flowchart illustrating the support for dynamic switching of secondary LCHs for PDU set transmission according to some embodiments of the present disclosure.

[0071] Figure 3 Relates to the UL data transmission between the UE and the BS. The UE can be the UE 101 as shown in Figure 1 and the BS can be the BS in any wireless communication system.

[0072] In operation 301, the BS can transmit a message to the UE, for example, an RRC message such as an RRC configuration message, and the message can configure the DRB to have multiple LCHs. The configuration can include the following:

[0073] - An indication indicating whether one or more RLC entities or one or more LCHs are configured for the DRB; for example, as shown in

[0074] Figure 2 , whether the DRB is configured with one or more of RLC entity 1, RLC entity 2,..., RLC entity N, and whether the DRB is configured with one or more of LCH 1, LCH 2,..., LCH M. - An indication indicating the priority of the LCH, for example, as shown in Figure 2 , this indication can indicate that the priority of LCH 1 is 1, the priority of LCH 2 is 2, the priority of LCH M is M, and so on.

[0075]

[0076] In some embodiments, the DRB may be configured with two LCHs. The LCH with a higher priority may be referred to as the primary LCH or the primary branch, and the LCH with a lower priority may be referred to as the secondary LCH or the secondary branch. In this case, the indication may be for the primary LCH (or the primary branch), which indicates that the RLC entity or the LCH is the primary branch, or the LCH is the primary LCH; or it may be for the secondary LCH (or the secondary branch), which indicates that the RLC entity or the LCH is the secondary branch, or the LCH is the secondary LCH.

[0077] - The association between one type of PDU set and one LCH (or one branch, one RLC entity). For example,

[0078] an association may indicate that when other LCHs are not activated, the LCH (or branch, RLC entity) with the highest priority is used to transmit all types of PDU sets. Another association may indicate that when other LCHs are activated, the LCH (or branch, RLC entity) with the highest priority is used to transmit one type of PDU set with the highest priority. Another association may indicate that when an LCH with a certain priority is activated, the LCH (or branch, RLC entity) with the corresponding priority is used to transmit one type of PDU set with the same priority. For example, the LCH with priority 5 is used to transmit the PDU set with priority 5.

[0079] In the case where there are two types of PDU sets (i.e., important and unimportant PDU sets) and two LCHs (i.e., primary and secondary

[0080] LCHs), examples of associations are as follows:

[0081] - When the secondary LCH is not activated, the primary LCH may be used to transmit both important PDU sets and unimportant PDU sets; and

[0082] - When the secondary LCH is activated, the primary LCH is used to transmit only important PDU sets, and the secondary LCH is used to transmit unimportant PDU sets.

[0083] Another example of an association is as follows:

[0084] - When the primary LCH is not activated, the secondary LCH may be used to transmit both important PDU sets and unimportant PDU sets; and

[0085] - When the primary LCH is activated, the primary LCH is used to transmit only important PDU sets, and the secondary LCH is used to transmit unimportant PDU sets.

[0086] - When the primary LCH is not activated, the secondary LCH may be used to transmit both important PDU sets and unimportant PDU sets; and

[0087] - When the primary LCH is activated, the primary LCH is used to transmit only important PDU sets, and the secondary LCH is used to transmit unimportant PDU sets.

[0088] - When the primary LCH is activated, the primary LCH is used to transmit only important PDU sets, and the secondary LCH is used to transmit unimportant PDU sets.

[0089] - When the primary LCH is activated, the primary LCH is used to transmit only important PDU sets, and the secondary LCH is used to transmit unimportant PDU sets.

[0090] - The default activation or deactivation state of an LCH that does not have the highest priority. For example, an LCH with a priority other than the highest priority is initially default-activated or deactivated.

[0091] In the case of two LCHs, this default activation or deactivation can be the initial activation or deactivation state of the secondary LCH. In other words, whether the secondary LCH is initially activated or deactivated is explicitly or implicitly indicated. In some embodiments, the secondary LCH can also be default-activated or deactivated. For another example, an LCH with a priority other than the lowest priority can be initially default-activated or deactivated.

[0092] Instances of the configuration can be included in an information element (IE) in the RRC configuration message, such as the PDCP-Config IE, as follows:

[0093] In the following of the present disclosure, a solution is described using two LCHs (or two branches, two RLC entities) and two types of PDU sets, and those skilled in the art know that other numbers of LCHs or other numbers of types of PDU sets can also be implemented in a similar manner by the solution.

[0094]

[0095] In operation 302, the UE can perform UL transmission with the BS. More specifically, the secondary LCH is not activated, and both types of PDU sets are transmitted using the primary LCH. In another example, if the primary LCH is not activated, then both types of PDU sets are transmitted using the secondary LCH.

[0096] In operation 303, the BS can determine that there is UL congestion and can determine to activate the secondary LCH. In another example, in the case where the secondary LCH is default-activated, the BS can determine to activate the primary LCH.

[0097] In operation 304, the BS can transmit an indication to the UE, such as a secondary LCH activation indication, which can indicate to the UE to activate the secondary LCH. In another example, in the case where the secondary LCH is default-activated, the BS can transmit an indication to the UE, such as a primary LCH activation indication, which can indicate to the UE to activate the primary LCH.

[0098] In some embodiments, the indication can be a MAC CE. For example, a secondary LCH activation MAC CE (or a split LCH activation indication MAC CE). In another example, a primary LCH activation MAC CE is used to activate the primary LCH.

[0099] In some embodiments, the indication can be a MAC CE. For example, a secondary LCH activation MAC CE (or a split LCH activation indication MAC CE). In another example, a primary LCH activation MAC CE is used to activate the primary LCH.

[0100] Figure 4Describe the secondary LCH activation indication MAC CE or the secondary LCH deactivation indication MAC CE according to some embodiments of the present disclosure. The primary LCH activation indication is designed in a similar manner.

[0101] The secondary LCH activation indication MAC CE or the secondary LCH deactivation indication MAC CE can be an octet identified by a MAC sub-header with a logical channel identifier (LCID). It can have a fixed size and can consist of a single octet containing eight D fields (taking 8 secondary LCHs as an example). The secondary LCH activation indication or the secondary LCH deactivation indication MAC CE can be defined for the MAC entity.

[0102] For one field, such as Di, this field can indicate the activation or deactivation status of the secondary LCH (or branch) i, where i can be an integer in the range from 0 to 7, and i is in ascending (or descending) order in the RRC configuration. The value "1" of the Di field can indicate that the secondary LCHi should be activated. The value "0" of the Di field can indicate that the secondary LCHi should be deactivated.

[0103] The secondary LCH activation indication or the secondary LCH deactivation indication MAC CE can also contain an identifier of the reference PDCP PDU (for simplicity, denoted as I PDCP ) or an identifier of the reference PDU set (for simplicity, denoted as I PDUset ), which indicates that the UE can activate the secondary LCH when transmitting the PDCP PDU with the identifier I PDCP or the PDU set with the identifier I PDUset . The identifier of the reference PDCP can also be a count value or a sequence number of the reference PDCP PDU, etc. The identifier of the reference PDU set can also be the sequence number of the PDU set.

[0104] In some embodiments, the secondary LCH activation indication or the secondary LCH deactivation indication can be carried by the PDCP control PDU.

[0105] Return reference Figure 3 , in operation 305, the UE can receive the secondary LCH activation indication. The MAC layer of the UE can forward the secondary LCH activation indication to the PDCP layer. The PDCP layer can route the PDCP PDU based on the association between the type of the PDU set and the LCH (i.e., based on the priorities of different PDU set types and based on the priorities of different LCHs (or different branches, different RLC entities)).

[0106] Taking two types of PDU sets (e.g., PDU set type 1 and PDU set type 2, or important PDU set and unimportant PDU set) as examples, and taking two LCHs (e.g., primary LCH and secondary LCH) as examples, in the case of activating the secondary LCH for a DRB, for PDU set type 1 or for the important PDU set, route the PDCP PDUs in the PDU set to the primary LCH; for PDU set type 2 or for the unimportant PDU set, route the PDCP PDUs in the PDU set to the secondary LCH.

[0107] Examples in 3GPP documents can be as follows:

[0108]

[0109] In operation 306, the UE can perform the transmission of PDU set type 1 through the primary LCH, and in operation 307, the UE can perform the transmission of PDU set type 2 through the secondary LCH.

[0110] In some embodiments, when the UE receives a secondary LCH activation indication, some PDCP PDUs of PDU set type 2 (or unimportant PDU set) may have been transmitted by the PDCP layer through the primary LCH (or primary branch), and there are still some remaining PDCP PDUs of PDU set type 2 to be transmitted. In this case, the present disclosure proposes the following options A1 to A3 for transmitting PDU set type 2.

[0111] - Option A1: The PDCP layer can route all PDCP PDUs of PDU set type 2 to the secondary LCH, where it should be noted that all PDCP PDUs of PDU set type 2 include the PDCP PDUs that have been transmitted.

[0112] - Option A2: The PDCP layer can continue to transmit the remaining PDCP PDUs of the PDU set through the primary LCH, and can start routing the next PDU set type 2 to the secondary LCH.

[0113] - Option A3: The PDCP layer can route the remaining PDCP PDUs of PDU set type 2 to the secondary LCH.

[0114] In some other cases, the secondary LCH activation indication may include an identifier of a reference PDCP PDU (e.g., I PDCP , a count value or a sequence number of the reference PDCP PDU) or an identifier of a reference PDU set (e.g., I PDUset ). In this case, when the UE is about to perform the transmission of a reference PDCP PDU with identifier I PDCP or a reference PDU set with identifier I PDUset , the UE can activate the secondary LCH (or secondary branch).

[0115] Figure 5 Describe the transmission of the PDU set of the DRB according to some embodiments of the present disclosure.

[0116] In Figure 5 , the PDU set 1 may have a higher priority, for example, an important PDU set or PDU set type 1, and the PDU set 1 may include one PDCP PDU, for example, PDCP PDU #3. The PDU set 2 may have a lower priority, for example, an unimportant PDU set or PDU set type 2, and the PDU set 2 may include two PDCP PDUs, for example, PDCP PDU #1 and PDCP PDU #2.

[0117] In the case where the secondary LCH is not activated, all three PDCP PDUs (i.e., PDCP PDU #1, PDCP PDU #2, and PDCP PDU #3) are transmitted by the primary LCH. When the UE receives a secondary LCH activation indication that does not indicate the identifier of the reference PDCP or reference PDU set, PDU #1 of the PDU set 2 has been successfully transmitted, and PDCP PDU #2 of the PDU set 2 has not been transmitted.

[0118] Regarding the transmission of the PDCP PDU of the PDU set 2, based on the above options A1 to A3, the PDCP layer may perform the following options a1 to a3:

[0119] - Option a1: The PDCP layer may route PDCP PDU #1 and PDCP PDU #2 to the secondary LCH, even if PDCP PDU #1 has been successfully transmitted to the primary LCH.

[0120] - Option a2: The PDCP layer may continue to transmit PDCP PDU #2 to the primary LCH and may start transmitting the PDCP PDUs of the next PDCP PDU set of PDU set type 2 to the secondary LCH.

[0121] - Option a3: The PDCP layer may route the remaining PDCP PDU #2 of the PDU set to the secondary LCH.

[0122] Figure 6 Describe the flowchart for supporting dynamic switching of the secondary LCH for PDU set transmission according to some embodiments of the present disclosure.

[0123] In operation 601, the UE may use the primary LCH to perform the transmission of PDU set type 1, and in operation 602, the UE may use the secondary LCH to perform the transmission of PDU set type 2.

[0124] In operation 603, the BS may determine UL congestion mitigation and may determine to deactivate the secondary LCH. In another example, the BS may also determine to deactivate the primary LCH, for which case, a similar method as listed below may be reused.

[0125] In operation 604, the BS may transmit an indication, e.g., a secondary LCH deactivation indication or a split LCH deactivation indication, to the UE via, for example, a MAC CE.

[0126] In operation 605, the UE may receive a secondary LCH deactivation indication MAC CE. The MAC layer of the UE may forward the secondary LCH deactivation indication to the PDCP layer. The PDCP layer may route all PDCP PDUs to the primary LCH.

[0127] In some embodiments, when the UE receives a secondary LCH deactivation indication, some PDCP PDUs of PDU set type 2 (or unimportant PDU set) may have been transmitted by the PDCP layer using the secondary LCH (or secondary branch), and there are still some remaining PDCP PDUs of PDU set type 2 to be transmitted. In this case, the present disclosure proposes the following options B1 to B3 for transmitting PDU set type 2.

[0128] - Option B1: The PDCP layer may route all PDCP PDUs of PDU set type 2 via the primary LCH, where it should be noted that all PDCP PDUs of PDU set type 2 include the PDCP PDUs that have been transmitted.

[0129] - Option B2: The PDCP layer may continue to transmit the remaining PDCP PDUs of PDU set type 2 via the secondary LCH and may start routing the next PDU set to the primary LCH. In this case, the secondary LCH may be deactivated after transmitting PDU set type 2.

[0130] - Option B3: The PDCP layer may route the remaining PDCP PDUs of PDU set type 2 to the primary LCH.

[0131] In some other cases, the secondary LCH deactivation indication may include an identifier of a reference PDCP PDU (denoted as I PDCP ) or an identifier of a reference PDU set (denoted as I PDUset ), which indicates that the UE may deactivate the secondary LCH when performing the transmission of the PDCP with identifier I PDCP or the PDU set with identifier I PDUset . The identifier of the reference PDCP PDU may be a count value or a sequence number, etc., of the reference PDCP PDU. The identifier of the reference PDCP set may be the sequence number of the reference PDCP set.

[0132] Return reference Figure 5, in the case where the secondary LCH is activated, the PDCP PDUs #1 and #2 of PDU set 2 are transmitted by the secondary LCH, and the PDCP PDU #1 is transmitted by the primary LCH. When the UE receives a secondary LCH deactivation indication that does not indicate an identifier of a reference PDCP or a reference PDU set, the PDU #1 of PDU set 2 has been successfully transmitted, and the PDU #2 of PDU set 2 has not been transmitted.

[0133] Regarding the transmission of the PDCP PDUs of PDU set 2, based on the above options B1 to B3, the PDCP layer may perform the following options b1 to b3:

[0134] - Option b1: The PDCP layer may route the PDCP PDUs #1 and #2 to the primary LCH, even if the PDCP PDU #1 has been successfully transmitted to the secondary LCH.

[0135] - Option b2: The PDCP layer may continue to transmit the PDCP PDU #2 to the primary LCH and may start transmitting the PDCP PDUs of the next PDCP PDU set to the primary LCH. In this case, the secondary LCH may be deactivated after transmitting the PDCP PDU #2.

[0136] - Option b3: The PDCP layer may route the remaining PDCP PDU #2 of PDU set 2 to the primary LCH.

[0137] In operation 606, the UE may use the primary LCH to perform the transmission of all PDCP PDUs of all PDU sets.

[0138] Solution 2:

[0139] In Solution 2, F1 signaling is introduced to support the activation or deactivation of the secondary LCH between the CU and the DU of the BS.

[0140] Figure 7 A flowchart illustrating the support for the dynamic switching of a secondary LCH or a secondary tunnel for PDU set transmission according to some embodiments of the present disclosure.

[0141] Figure 7 It involves the UL data transmission between the UE and the DU, and the DL data transmission between the CU and the DU. The UE may be the UE 101 as shown in Figure 1 , the DU may be the DU 102A in Figure 1 , and the CU may be the CU 104 in Figure 1 .

[0142] In Figure 7 , the secondary LCH or the secondary tunnel is not initially activated. In another instance, it is also possible that the primary LCH or the primary tunnel is not activated, while the secondary LCH or the secondary tunnel is initially activated.

[0143] The operations between the UE and the DU (e.g., gNB-DU), i.e., operations 701 to 706, are respectively similar to operations 302 to 307 in Figure 3 and the details are omitted here. It should be noted that the operations between the UE and the DU (i.e., operations 701 to 706) and the operations between the DU and the CU (i.e., operations 702 and 711 to 716) can be independent.

[0144] In operation 711, the DU and the CU (e.g., gNB-CU) can perform the transmission of both PDU set type 1 and PDU set type 2 through the primary tunnel between the DU and the CU (e.g., F1-U tunnel).

[0145] In operation 702, the DU can determine to activate the secondary F1-U tunnel.

[0146] In operation 713, the DU can transmit an indication to the CU, e.g., a secondary LCH activation indication, a split LCH activation indication, or a secondary tunnel activation indication, which can indicate to the CU to activate the secondary tunnel (e.g., secondary F1-U tunnel). The secondary LCH activation indication can be carried by an F1-AP message or carried on the F1 user plane protocol.

[0147] In some other cases, the secondary LCH activation indication can be included in an F1-U frame (e.g., a DL data delivery status frame on the primary F1-U tunnel), or included in a message (e.g., an F1 AP UE context modification message required).

[0148] The secondary LCH activation indication can further include an identifier of a reference PDCP PDU (for simplicity, denoted as I PDCP ) or an identifier of a reference PDU set (for simplicity, denoted as I PDUset ), which indicates that the CU can activate the secondary tunnel when performing the transmission of the PDCP PDU with the identifier I PDCP or the PDU set with the identifier I PDUset .

[0149] In operation 714, the CU can perform PDCP routing for different PDU sets for DL data transmission. More specifically, the CU can route the DL PDCP PDUs based on the association between the type of the PDU set and the F1-U tunnel.

[0150] Taking two types of PDU sets (for example, PDU set type 1 and PDU set type 2, or important PDU set and unimportant PDU set) as an example, and taking two F1-U tunnels as an example, in the case of activating a secondary tunnel for a DRB, for PDU set type 1 (or important PDU set), route the PDCP PDUs in PDU set type 1 to the primary F1-U tunnel; for PDU set type 2 (or unimportant PDU set), route the PDCP PDUs in PDU set type 2 to the secondary F1-U tunnel.

[0151] In some embodiments, when the CU receives an indication to activate a secondary tunnel, some PDCP PDUs of PDU set type 2 (or unimportant PDU set) may have been transmitted using the primary tunnel, and there are still some remaining PDCP PDUs of PDU set type 2 to be transmitted. In this case, the present disclosure proposes the following options C1 to C3 for transmitting PDU set type 2.

[0152] - Option C1: The CU may route all PDCP PDUs of PDU set type 2 via the secondary tunnel, where it should be noted that all PDCP PDUs of PDU set type 2 include the PDCP PDUs that have been transmitted.

[0153] - Option C2: The CU may continue to transmit the remaining PDCP PDUs of PDU set type 2 via the primary tunnel, and may start routing the next PDU set to the secondary tunnel.

[0154] - Option C3: The CU may route the remaining PDCP PDUs of PDU set type 2 to the secondary tunnel.

[0155] In operation 715, the CU may perform the transmission of PDU set type 1 using the primary tunnel, and in operation 716, the CU may perform the transmission of PDU set type 2 using the secondary tunnel.

[0156] Figure 8 A flowchart illustrating the dynamic switching of a secondary LCH or secondary tunnel for supporting PDU set transmission according to some embodiments of the present disclosure.

[0157] In Figure 8 the secondary LCH or secondary tunnel is initially activated.

[0158] The operations between the UE and the DU (for example, gNB-DU) (i.e., operations 801 to 806) are respectively similar to the operations 601 to 606 in Figure 6 and the details are omitted here. It should be noted that the operations between the UE and the DU (i.e., operations 801 to 806) and the operations between the DU and the CU (i.e., operations 803 and 811 to 816) may be independent.

[0159] In operation 811, the DU and the CU (e.g., gNB-CU) may perform DL transmission of PDU set type 1 via the primary tunnel (e.g., F1-U tunnel) between the DU and the CU.

[0160] In operation 812, the DU and the CU may perform DL transmission of PDU set type 2 via the secondary tunnel (e.g., F1-U tunnel) between the DU and the CU.

[0161] In operation 803, the DU may determine to deactivate the secondary F1-U tunnel.

[0162] In operation 814, the DU may transmit an indication to the CU, e.g., a secondary LCH deactivation indication, a split LCH deactivation indication, or a secondary tunnel deactivation indication, which may indicate to the CU to deactivate the secondary tunnel (e.g., the secondary F1-U tunnel). The secondary LCH deactivation indication may be carried by an F1-AP message or carried on the F1 user plane protocol.

[0163] In some other cases, the secondary LCH deactivation indication may be included in an F1-U frame (e.g., a DL data delivery status frame on the primary F1-U tunnel), or included in a message (e.g., a required F1 AP UE context modification message).

[0164] The secondary LCH deactivation indication may further include an identifier of a reference PDCP PDU (for simplicity, denoted as I PDCP ) or an identifier of a reference PDU set (for simplicity, denoted as I PDUset ), which indicates that the CU may deactivate the secondary tunnel when performing the transmission of the PDCP PDU with identifier I PDCP or the PDU set with identifier I PDUset .

[0165] In operation 815, the CU may perform PDCP routing for different PDU sets for DL data transmission. More specifically, the CU may route all DL PDCP PDUs to the primary tunnel.

[0166] In some embodiments, when the CU receives an indication to deactivate the secondary tunnel, some PDCP PDUs of PDU set type 2 (or unimportant PDU sets) may have been transmitted using the secondary tunnel, and there are still some remaining PDCP PDUs of PDU set type 2 to be transmitted. In this case, the present disclosure proposes the following options D1 to D3 for transmitting PDU set type 2.

[0167] - Option D1: The CU may route all PDCP PDUs of PDU set type 2 via the primary tunnel, even if some PDCP PDUs of PDU set type 2 may have been transmitted using the secondary tunnel.

[0168] - Option D2: The CU can continue to transmit the remaining PDCP PDUs of PDU set type 2 via the secondary tunnel and can start routing the next PDU set type 2 to the primary tunnel. In this case, the secondary tunnel can be deactivated after transmitting the PDU set type 2.

[0169] - Option D3: The CU can route the remaining PDCP PDUs of PDU set type 2 to the primary tunnel.

[0170] In operation 816, the CU can use the primary tunnel to perform the transmission of all PDU sets.

[0171] In some other embodiments, the CU can determine whether to activate or deactivate the secondary tunnel (e.g., the secondary F1-U tunnel). The CU can transmit an indication to the DU, such as a secondary LCH activation indication or a secondary LCH deactivation indication. Then the CU can perform DL data transmission with the DU using both the primary tunnel and the secondary tunnel. The indication can also include an identifier of a reference PDCP PDU or a reference PDU set.

[0172] In some embodiments, after receiving the indication, the DU can transmit an indication to the UE, such as a secondary LCH activation indication or a secondary LCH deactivation indication, and can perform DL data transmission with the UE using the primary LCH (or the primary branch) and the secondary LCH (or the secondary branch). The indication can also include an identifier of a reference PDCP PDU or a reference PDU set.

[0173] Figure 9 Describe a method performed by a UE according to some embodiments of the present disclosure.

[0174] In operation 901, the UE can receive a secondary LCH activation indication for activating a secondary LCH of a DRB via a transceiver from the BS; and in operation 902, in response to receiving the secondary LCH activation indication from the BS, the UE can activate the secondary LCH of the DRB; and in operation 903, after activating the secondary LCH of the DRB, the UE can route the PDCP PDUs of a PDU set through the secondary LCH of the DRB.

[0175] In some embodiments, the secondary LCH activation indication is received by the UE's MAC CE or PDCP control PDU.

[0176] In some embodiments, the UE can receive an RRC message that includes at least one of the following: a second indication indicating whether the DRB is configured with a primary LCH and a secondary LCH; a third indication indicating whether the LCH is a primary LCH or a secondary LCH; an association between the type of a PDU set and an LCH; or a default activation or deactivation state of the secondary LCH. For example, in operation 301, the UE can receive an RRC message, an RRC configuration message.

[0177] In some embodiments, the association indication indicates that the type of PDU set with the second priority (e.g., PDU set type 2) is to be associated with the secondary LCH, or indicates that both the type of PDU set with the first priority (e.g., PDU set type 1) and the type of PDU set with the second priority (e.g., PDU set type 2) are to be associated with the primary LCH and the secondary LCH, respectively.

[0178] In some embodiments, the UE may perform one of the following: when the type of the first PDU set has the first priority (e.g., PDU set type 1), route all PDCP PDUs in the first PDU set to the primary LCH; and when the type of the second PDU set has the second priority (e.g., PDU set type 2), where the second priority is lower than the first priority, route all PDCP PDUs in the second PDU set to the secondary LCH.

[0179] In some embodiments, when there are remaining PDCP PDUs of the PDU set with the second priority to be transmitted using the primary LCH, the processor is further configured to perform one of the following: route all PDCP PDUs of the PDU set with the second priority (e.g., PDU set type 2) to the secondary LCH; route the next PDU set with the second priority (e.g., PDU set type 2) to the secondary LCH; or route the remaining PDCP PDUs of the PDU set with the second priority (e.g., PDU set type 2) to the secondary LCH.

[0180] In some embodiments, the UE may receive, via the transceiver, a secondary LCH deactivation indication from the BS for deactivating the secondary LCH of the DRB; and the UE may deactivate the secondary LCH of the DRB; and route the PDCP PDUs of the PDU set through the primary LCH in response to receiving the secondary LCH deactivation indication from the BS.

[0181] In some embodiments, the UE may receive, via the transceiver, a secondary LCH deactivation indication from the BS for deactivating the secondary LCH of the DRB, and there are remaining PDCP PDUs of the PDU set with the second priority to be transmitted using the secondary LCH, and in response to receiving the secondary LCH deactivation indication from the BS, the UE may perform one of the following: route all PDCP PDUs of the PDU set with the second priority to the primary LCH; route the next PDU set with the second priority to the primary LCH; or route the remaining PDCP PDUs of the PDU set with the second priority to the primary LCH.

[0182] In some embodiments, the secondary LCH activation indication includes an identifier of a reference PDCP PDU or an identifier of a reference PDU set, and the processor is further configured to: activate the secondary LCH after transmitting the reference PDCP PDU or the reference PDU set.

[0183] In some embodiments, the secondary LCH deactivation indication includes an identifier of a reference PDCP PDU or an identifier of a reference PDU set, and the processor is further configured to: deactivate the secondary LCH after transmitting the reference PDCP PDU or the reference PDU set.

[0184] Figure 10 Describe a method performed by a DU according to some embodiments of the present disclosure.

[0185] In operation 1001, the DU may determine a secondary LCH activation indication for activating a secondary LCH of a DRB or a secondary tunnel; and in operation 1002, the DU may transmit the secondary LCH activation indication via a transceiver.

[0186] In some embodiments, the secondary LCH activation indication is transmitted to the UE and carried by a MAC CE or a PDCP control PDU. In some embodiments, the secondary LCH activation indication is transmitted to the CU and is included in the F1 signaling or the F1 user plane protocol.

[0187] In some embodiments, the DU may perform one of the following: determine a secondary LCH deactivation indication for deactivating a secondary LCH of a DRB or a secondary tunnel; and transmit the secondary LCH deactivation indication via a transceiver.

[0188] Figure 11 Describe a method performed by a CU according to some embodiments of the present disclosure.

[0189] In operation 1101, the CU may activate a secondary tunnel; and in operation 1102, the CU may route PDCU PDUs of a PDU set through the secondary tunnel after activating the secondary tunnel.

[0190] In some embodiments, the CU may perform one of the following: route all PDCP PDUs in a first PDU set to a primary tunnel when the type of the first PDU set has a first priority; and route all PDCP PDUs in a second PDU set to a secondary tunnel when the type of the second PDU set has a second priority, where the second priority is lower than the first priority.

[0191] In some embodiments, in a case where there are remaining PDCP PDUs of a PDU set with a second priority to be transmitted using a primary tunnel, the processor is further configured to perform one of the following: route all PDCP PDUs of the PDU set with the second priority to a secondary tunnel; route the next PDU set with the second priority to the secondary tunnel; or route the remaining PDCP PDUs of the PDU set with the second priority to the secondary tunnel.

[0192] In some embodiments, the CU may deactivate the secondary tunnel; deactivate the secondary tunnel; and route the PDCP PDUs of the PDU set through the primary tunnel in response to deactivating the secondary tunnel.

[0193] In some embodiments, the CU may deactivate the secondary tunnel, and in a case where there are remaining PDCP PDUs of a PDU set with a second priority to be transmitted using the secondary tunnel; after deactivating the secondary tunnel, perform one of the following: route all PDCP PDUs of the PDU set with the second priority to the primary tunnel; route the next PDU set with the second priority to the primary tunnel; or route the remaining PDCP PDUs of the PDU set with the second priority to the primary tunnel.

[0194] In some embodiments, determine an identifier of a reference PDCP PDU or an identifier of a reference PDU set, and the CU may activate the secondary tunnel after transmitting the reference PDCP PDU or the reference PDU set.

[0195] In some embodiments, determine an identifier of a reference PDCP PDU or an identifier of a reference PDU set, and the CU may deactivate the secondary tunnel after transmitting the reference PDCP PDU or the reference PDU set.

[0196] Figure 12 A simplified block diagram of a device according to some embodiments of the present disclosure is illustrated.

[0197] As Figure 12 shown, an example of device 1200 may include at least one processor 1204 and at least one transceiver 1202 coupled to processor 1204. Device 1200 may be a UE, a BS, a CU, a DU, or any other device with similar functionality.

[0198] Although elements such as at least one transceiver 1202 and processor 1204 are described in singular form in this figure, the plural form is contemplated unless explicitly limited to the singular form. In some embodiments of the present disclosure, transceiver 1202 may be divided into two devices, such as a receiving circuitry and a transmitting circuitry. In some embodiments of the present disclosure, device 1200 may further include an input device, a memory, and / or other components.

[0199] In some embodiments of the present disclosure, the device 1200 may be a UE, a CU, or a DU. The transceiver 1202 and the processor 1204 may interact with each other to perform the operations of the UE, CU, or DU described in any one of Figures 1 to 11 therein.

[0200] In some embodiments of the present disclosure, the device 1200 may further include at least one non-transitory computer-readable medium.

[0201] For example, in some embodiments of the present disclosure, the non-transitory computer-readable medium may store computer-executable instructions thereon to cause the processor 1204 to implement the methods for the UE, CU, or DU as described above. For example, when the computer-executable instructions are executed, they cause the processor 1204 to interact with the transceiver 1202 to perform the operations of the UE, CU, or DU described in any one of Figures 1 to 11 therein.

[0202] In some embodiments of the present disclosure, the non-transitory computer-readable medium may store computer-executable instructions thereon to cause the processor 1204 to implement the methods for the node as described above. For example, when the computer-executable instructions are executed, they cause the processor 1204 to interact with the transceiver 1202 to perform the operations of the node described in any one of Figures 1 to 11 therein.

[0203] The methods of the present disclosure may be implemented on a programmed processor. However, the controllers, flowcharts, and modules may also be implemented on a general-purpose or special-purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit elements, an integrated circuit, a hardware electronic or logic circuit (such as a discrete element circuit), a programmable logic device, etc. Generally, any device having a finite state machine capable of implementing the flowcharts shown in the figures may be used to implement the processing functions of the present disclosure.

[0204] Although the present disclosure has been described in terms of its specific embodiments, it is obvious that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, the various components of the embodiments may be interchanged, added, or replaced in other embodiments. In addition, all the elements shown in each figure are not necessary for the operation of the disclosed embodiments. For example, those skilled in the art of the disclosed embodiments will be able to make and use the teachings of the present disclosure by simply adopting the elements of the independent claims. Therefore, the embodiments of the present disclosure set forth herein are intended to be illustrative rather than restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0205] In this disclosure, relational terms such as "first", "second", etc. may be used solely to distinguish one entity or action from another entity or action, and do not necessarily require or imply any actual such relationship or order between such entities or actions. The term "comprises / comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element that begins with "a", "an", etc. does not, without further limitation, preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element. Additionally, the term "another" is defined as at least a second or more. As used herein, the terms "including", "having", etc. are defined as "comprising".

Claims

1. A user equipment (UE) comprising: A transceiver; And A processor coupled to the transceiver and configured to: Receive, via the transceiver, a secondary logical channel (LCH) activation indication for activating a data radio bearer (DRB) from a base station (BS); and In response to receiving the secondary LCH activation indication from the BS: Activate the secondary LCH of the DRB; and After activating the secondary LCH of the DRB, route a packet data convergence protocol (PDCP) protocol data unit (PDU) set of the DRB through the secondary LCH.

2. The UE according to claim 1, wherein the secondary LCH activation indication is received by a medium access control control element (MAC CE) or a PDCP control PDU of the UE.

3. The UE according to claim 1, wherein the processor is further configured to: Receive a radio resource control (RRC) message, the RRC message including at least one of the following: A second indication indicating whether the DRB is configured with a primary LCH and the secondary LCH; A third indication indicating whether the LCH is a primary LCH or a secondary LCH; An association between a type of the PDU set and the LCH; or A default activation or deactivation state of the secondary LCH.

4. The UE according to claim 1, wherein the processor is further configured to perform one of the following: when a type of a first PDU set has a first priority, route all PDCP PDUs in the first PDU set to the primary LCH; and When a type of a second PDU set has a second priority, wherein the second priority is lower than the first priority, route all PDCP PDUs in the second PDU set to the secondary LCH.

5. The UE according to claim 1, wherein when there are remaining PDCP PDUs of a PDU set with a second priority to be transmitted using the primary LCH, the processor is further configured to perform one of the following: route all PDCP PDUs of the PDU set with the second priority to the secondary LCH; Route the next PDU set with the second priority to the secondary LCH; Or Route the remaining PDCP PDUs of the PDU set with the second priority to the secondary LCH.

6. The UE according to claim 1, wherein the processor is further configured to: Receive, via the transceiver, a secondary LCH deactivation indication for deactivating the secondary LCH of the DRB from the BS; and In response to receiving the secondary LCH deactivation indication from the BS, Deactivate the secondary LCH of the DRB; and Route the PDCP PDUs of the PDU set through the primary LCH.

7. The UE according to claim 1, wherein the processor is further configured to: receiving, via the transceiver, a secondary LCH deactivation indication for deactivating the secondary LCH of the DRB from the BS, and there are remaining PDCP PDUs of the PDU set with a second priority to be transmitted using the secondary LCH, In response to receiving the secondary LCH deactivation indication from the BS, performing one of the following: routing all PDCP PDUs of the PDU set having the second priority to a primary LCH; routing the next set of PDUs having the second priority to the primary LCH; or The remaining PDCP PDUs of the PDU set having the second priority are routed to the primary LCH.

8. The UE of claim 6, wherein the secondary LCH deactivation indication comprises an identifier of a reference PDCP PDU or an identifier of a reference PDU set, and the processor is further configured to: The secondary LCH is deactivated after transmitting the reference PDCP PDU or the reference PDU set.

9. A distributed unit DU, comprising: transceiver; and a processor coupled to the transceiver and configured to: determining a secondary LCH activation indication for activating a secondary logical channel LCH or a secondary tunnel of a data radio bearer DRB; and The secondary LCH activation indication is transmitted via the transceiver.

10. The DU according to claim 9, wherein the secondary LCH activation indication is transmitted to the UE and carried by a medium access control element (MAC CE) or a PDCP control PDU. 11 . The DU according to claim 9 , wherein the secondary LCH activation indication is transmitted to a central unit (CU) and included in F1 signaling or F1 user plane protocol.

12. The DU of claim 9, wherein the processor is further configured to perform one of: determining a secondary LCH deactivation indication for deactivating the DRB or the secondary LCH of the secondary tunnel; and The secondary LCH deactivation indication is transmitted via the transceiver.

13. A central unit (CU), comprising: transceiver; and a processor coupled to the transceiver and configured to: Activate the secondary tunnel; and After activating the secondary tunnel, a Packet Data Convergence Protocol (PDCP) PDU of a Protocol Data Unit (PDU) set is routed through the secondary tunnel.

14. The CU of claim 13, wherein, in a case where there are remaining PDCP PDUs of the PDU set with a second priority to be transmitted using the primary tunnel, the processor is further configured to perform one of: routing all PDCP PDUs of the PDU set with the second priority to the secondary tunnel; routing a next set of PDUs having the second priority to the secondary tunnel; or The remaining PDCP PDUs of the PDU set having the second priority are routed to the secondary tunnel.

15. The CU of claim 13, wherein the processor is further configured to: deactivating the secondary tunnel and, if there are remaining PDCP PDUs of the PDU set with the second priority to be transmitted using the secondary tunnel; After deactivating the secondary tunnel, one of the following is performed: Route all PDCP PDUs of the PDU set with the second priority to the primary tunnel; Route the next PDU set with the second priority to the primary tunnel; or Route the remaining PDCP PDUs of the PDU set with the second priority to the primary tunnel.

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