CN110089151B - System and method for packet forwarding during handover procedure - Google Patents

Abstract

The techniques described herein may enable packet forwarding during handover (HO) procedures involving fifth generation (5G) technologies. During the HO procedure, the source radio access network (RAN) node may send user data packets intended for user equipment (UE) to the target RAN node. Each packet may be assigned a sequence number (SN) based on the quality of service (QoS) or data radio bearer (DRB) used by the source RAN node to send the packet to the UE. The target RAN node may use the same DRB to forward the packet to the UE, use a different DRB to forward the packet to the UE, or use a different QoS to forward the packet to the UE. The target RAN node may also or alternatively create a record of packets forwarded to the UE to enable retransmission of packets when appropriate.

Description

System and method for packet forwarding during handover procedure

Related applications

This application claims the benefit of US Provisional Patent Application No. 62/436,900, filed on December 20, 2016, the contents of which are hereby incorporated by reference as if fully set forth herein.

technical field

The present application relates to systems and methods for packet forwarding during handover procedures.

Background technique

A wireless communication network may include user equipment (UE) (eg, smartphones, tablets, laptops, etc.), radio access network (RAN) nodes (eg, base stations), and a core network. The UE may connect to the core network by communicating with the RAN node and registering with the core network. Communication between a UE and a RAN node (also referred to herein as an access node) may occur on signal carriers corresponding to frequency bands.

As the UE moves to different coverage areas within the wireless communication network, the UE may participate in one or more handover (HO) procedures. Handover (HO) procedures may include procedures in which a UE is transferred from one access node to another access node (commonly referred to herein as source node and target node, respectively). Before the HO procedure, the source node may receive information directed to the UE from the core network and temporarily store the information in a buffer memory before transmitting the information to the UE. When the source node determines to handover the UE to the target node, some information intended for the UE may still be stored in the source node's buffer memory. In this way, in addition to enabling the UE to connect to the target node, the HO procedure may include the source node providing buffered data to the target node and the target node sending data to the UE (after the connection between the target node and the UE has been established) ).

SUMMARY OF THE INVENTION

According to an aspect of the present disclosure, there is provided an apparatus for a radio access network RAN node, the apparatus comprising: an interface of a radio frequency RF circuit; and one or more processors for: inserting a sequence number SN into a plurality of In each user data packet of the user data packet, the plurality of user data packets are directed to the user equipment UE connected to the RAN node, and the SN is based on the relative order position of each user data packet of the plurality of user data packets; And before causing at least one user data packet of the plurality of user data packets to be transmitted to the UE via the RF circuit, as part of a handover procedure, it is determined that the UE is to be transferred to a target RAN node, and all at the handover procedure, together with an indication of how the at least one user data packet would have been transmitted by the RAN node to the UE via the interface of the RF circuit prior to the handover procedure is transferred to the target RAN node during the procedure.

According to another aspect of the present disclosure, there is provided an apparatus for a radio access network RAN node, the apparatus comprising: an interface to a radio frequency RF circuit; and one or more processors for: a source RAN node from a handover procedure A plurality of user data packets are received, the plurality of user data packets are directed to the user equipment UE corresponding to the handover process, and each user data packet of the plurality of user data packets includes each user data packet based on the plurality of user data packets. the sequence number SN of the relative sequential position of the user data packets; received from the source RAN node how each of the plurality of user data packets would have been transmitted by the source RAN node to the source RAN node prior to the handover procedure an indication of the UE; based on the indication, determining a data radio bearer DRB for transmitting the plurality of user data packets to the UE; via the interface of the RF circuit as part of the handover procedure receiving an indication that the UE is ready to communicate with the RAN node; and causing the plurality of user data packets to be transmitted to the UE via the interface of the RF circuit using the DRB.

According to another aspect of the present disclosure, there is provided an apparatus for user equipment UE, the apparatus comprising: an interface of a radio frequency RF circuit; and one or more processors for: from the interface via the RF circuit The first radio access network RAN node receives a plurality of first user data packets, each user data packet of the plurality of first user data packets includes a user data packet based on each user data packet of the plurality of first user data packets. sequence number SN of a sequential position; receiving instructions via said interface of said RF circuit to participate in a handover procedure involving said first RAN node and a second RAN node; as part of said handover procedure, via said RF circuit's The interface receives a plurality of second user data packets from the second RAN node, each user data packet of the plurality of second user data packets comprising relative to the plurality of first user data packets on a per user data packet basis SN of sequential positions of data packets and said plurality of second user data packets, wherein said second RAN node received said plurality of second user data packets from said first RAN node and said plurality of second user data packets prior to said handover procedure an indication of how each user data packet of the plurality of second user data packets would have been transmitted by the first RAN node to the UE, and wherein the second RAN node converts the plurality of first user data packets based on the indication Each user data packet of two user data packets is sent to the UE; and based on the SN of each user data packet of the plurality of first user data packets and the plurality of second user data packets, the plurality of user data packets are sent to the UE. A first user data packet is combined with the plurality of second user data packets.

Description of drawings

Embodiments described herein will be readily understood from the following detailed description taken in conjunction with the accompanying drawings. For convenience of description, the same reference numerals may denote the same structural elements. Embodiments are shown in the drawings by way of example and not limitation.

1 illustrates the architecture of a system of networks according to some embodiments;

2 is a sequence flow diagram of an example process of packet forwarding during a handover procedure, wherein a source node and a target node communicate with user equipment (UE) using the same data radio bearer (DRB);

3 is a sequence flow diagram of an example process for packet forwarding based on Quality of Service (QoS) IDs during a handover procedure;

4 is a sequential flow diagram of an example process of packet forwarding during a handover process, wherein the source node and the target node use different DRBs;

5 and 6 are sequence flow diagrams of examples of detailed processes for packet forwarding during a handover process;

Figure 7 illustrates example components of a device according to some embodiments;

Figure 8 illustrates an example interface for a baseband circuit in accordance with some embodiments; and

9 is a diagram illustrating the ability to read instructions from a machine-readable or computer-readable medium (eg, a non-transitory machine-readable storage medium) and perform any one or more of the methods discussed herein, according to some example embodiments A block diagram of the components.

Detailed ways

The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description should not be considered in a limiting sense, and the scope of the embodiments is defined by the appended claims and their equivalents.

In a wireless communication network, a handover (HO) procedure may include a UE's transfer from one access node to another access node (commonly referred to as source node and target node, respectively). When the source node decides to hand over the UE, some information intended for the UE may still be stored in the source node's buffer memory. In this way, in addition to enabling the UE to connect to the target node, the HO procedure may include the source node providing the UE's buffered data to the target node, and after the connection between the target node and the UE has been established, the target node transfers the data to the target node. sent to the UE.

In some scenarios, such as using Long Term Evolution (LTE) Radio Access Technology (RAT), providing buffered data to the UE may involve using Packet Data Convergence Protocol (PDCP) to assign a sequence number (SN) to a sequence number (SN) intended for the UE Packet Data Unit (PDU). The SN may enable the UE to determine which PDUs have been received and which PDUs have not, and take appropriate action (such as requesting that one or more PDUs be resent to the UE). Furthermore, each data radio bearer (DRB) used to transmit data to the UE may have its own PDCP instance so that the SN assigned to PDUs transmitted over a particular DRB may not depend on the SN assigned to PDUs transmitted over a different DRB Or related to the SNs assigned to PDUs transmitted over different DRBs. A SN may be assigned to a PDU in preparation for transmission to the UE before and/or while the PDU is stored in the memory buffer.

Regarding the HO procedure, where the PDUs stored in the memory buffer of the source node are forwarded to the target node and then to the UE, it is useful to preserve the SN of the PDUs so that the UE can compare the PDUs from the source node with the PDUs from the target node The PDUs are merged to arrange the PDUs in the proper order and/or to determine if all PDUs in a given order have been successfully received. When the UE determines that one or more PDUs are lost, the UE may request that the PDUs be resent by the target node, and in response, the target node may resend all PDUs in a given set or only the lost PDUs. When retransmitting all PDUs, the UE can detect (based on SN) which PDUs are duplicates and delete/ignore duplicate PDUs. Since the above procedure enables the UE to arrange PDUs from the source and target nodes in the proper order and to request retransmission of lost packets, the procedure is sometimes characterized as delivering data to UEs participating in the HO procedure without loss of order.

Aspects of LTE that may enable the SN assigned by the source node to be used by the target node may include ensuring that the source node and the target node are using the same DRB to send data to the UE. However, in New Radio (NR) technologies (eg, Next Generation Node Bs (gNBs) and eNBs connected to the NR core network), the mapping of data to DRBs can be up to RAN nodes (ie, eNBs, gNBs, etc.). Therefore, the source node and the target node may end up using different DRBs to send data to the UE undergoing the HO procedure. In such a scenario, if the target node uses a different DRB than the source node, the target node may assign a SN to a PDU that does not correspond to the SN of a PDU previously sent by the source node to the UE. Consequently, the UE may not be able to combine the PDUs from the source node with the PDUs from the target node to arrange the PDUs in the proper order and/or may not be able to determine whether all PDUs for a given transmission have been successfully received.

The techniques described herein may be used to enable sequential lossless delivery of data to UEs participating in HO procedures involving NR techniques (eg, gNBs, eNBs connected to an NR core network, etc.). In one example, the source node may indicate which DRB is being used by the source node to transmit the PDU to the UE, and the target node may use the same DRB to forward the PDU received from the source node to the UE. Once the UE has successfully received the PDU, the target node can reconfigure according to its own preferences which DRBs are used to send subsequent PDUs to the UE.

In another example, access nodes (eg, source and target nodes) may assign SNs to PDUs based on criteria, attributes, characteristics, etc. other than the DRB used to transmit the PDU. For example, the SN assigned to the PDU may be based on the QoS flow corresponding to the PDU. In this way, two different QoS flows can have different numbering order in PDCP even/when they belong to the same DRB. Since the QoS flow can be maintained during and after the HO procedure, the SNs of the PDUs sent to the UE can be sequential and lossless.

In another example, each PDU may include an SN assigned by the source node and an SN assigned by the target node. For example, a PDU sent from a source node to a target node may include an SN assigned by the source node and an indication of the manner in which the source node transmitted the PDU to the UE (eg, one or more conditions under that manner, etc.). An example of this indication may include the DRB ID corresponding to the DRB used by the source node to send the PDU to the UE. In some embodiments, different types of identifiers (eg, in addition to DRB IDs) may be used to map data packets to DRBs. In another example, this indication may include a QoS ID corresponding to the quality of service (QoS) used by the source node to send the PDU to the UE. In some embodiments, different types of identifiers (eg, in addition to QoS IDs) may be used to map data packets to DRBs.

The target node can then assign another SN to the PDU, such that each PDU includes two SNs, one assigned by the source node and the other assigned by the target node. The target node can send the PDU to the UE, and the UE can combine the PDUs previously received from the source node with the PDUs received from the target node using the DRB ID and SN from the source node. Furthermore, when the UE finds that a specific PDU is not received, the UE may request to retransmit the PDU based on the SN assigned by the source node or the SN assigned by the target node.

In some embodiments, the source node may use one or more techniques to determine which buffered PDUs to send to the target node for transmission to the UE. In one example, when the source node sends PDUs to the UE, the source node can monitor which PDUs the UE acknowledges (eg, successfully received). In this way, if/when the time comes for the HO procedure involving the UE, the source node can determine the oldest PDU that has not received an acknowledgment from the UE, and can send all PDUs starting from the oldest PDU that has not yet been acknowledged by the UE to the target node. In this case, some of the PDUs sent to the target node may include PDUs that have been acknowledged by the UE but are not as old as the oldest, unacknowledged PDUs. In another example, the source node may only send unacknowledged PDUs to the target node. In some embodiments, some PDUs received from the source node may not have been assigned a SN, and the target node may recognize such PDUs and process them appropriately (eg, according to one of the examples above). Furthermore, the techniques described herein may be applied in conjunction with existing HO procedure techniques, such as those described above with reference to the LTE RAT.

FIG. 1 illustrates the architecture of a system 100 of a network in accordance with some embodiments. System 100 is shown including UE 101 and UE 102 . UEs 101 and 102 are shown as smart phones (eg, handheld touchscreen mobile computing devices connectable to one or more cellular networks), but may also include any mobile or non-mobile computing devices such as personal data assistants (PDAs), pagers , laptop computer, desktop computer, wireless handheld device, or any computing device that includes a wireless communication interface.

In some embodiments, either of UEs 101 and 102 may include Internet of Things (IoT) UEs, which may include a network access layer designed for low-power IoT applications utilizing short-term UE connections. IoT UEs may utilize technologies such as Machine-to-Machine (M2M) or Machine-Type Communication (MTC) to communicate via Public Land Mobile Networks (PLMN), Proximity Services (ProSe) or Device-to-Device (D2D), sensor networks or IoT networks Exchange data with MTC servers or devices. M2M or MTC data exchanges can be machine-initiated data exchanges. An IoT network describes interconnected IoT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure) with short-lived connections. IoT UEs can execute background applications (eg, keep-alive messages, status updates, etc.) to facilitate connectivity to the IoT network.

UEs 101 and 102 may be configured to be connected (eg, communicatively coupled) with a Radio Access Network (RAN) 110 - RAN 110 may be, eg, Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN) ), NextGen RAN (NG RAN), or other types of RAN. UEs 101 and 102 utilize connections 103 and 104, respectively, each connection comprising a physical communication interface or layer (discussed in further detail below); in this example, connections 103 and 104 are shown as air interfaces for enabling communication coupling, and may Compliant with cellular communication protocols such as Global System for Mobile Communications (GSM) protocol, Code Division Multiple Access (CDMA) network protocol, Push to Talk (PTT) protocol, PTT over Cellular (POC) protocol, Universal Mobile Telecommunications System (UMTS) protocol , 3GPP Long Term Evolution (LTE) protocol, Fifth Generation (5G) protocol, New Radio (NR) protocol, etc.

In this embodiment, the UEs 101 and 102 can also directly exchange communication data via the ProSe interface 105 . ProSe interface 105, which may alternatively be referred to as a sidelink interface, includes one or more logical channels including, but not limited to, Physical Sidelink Control Channel (PSCCH), Physical Sidelink Shared Channel (PSSCH), Physical Sidelink Discovery Channel (PSDCH) and Physical Sidelink Broadcast Channel (PSBCH).

路由器。在该示例中，AP 106被示为连接到互联网而不连接到无线系统的核心网(下面进一步详细描述)。UE 102 is shown configured to access access point (AP) 106 via connection 107 . Connection 107 may include a local wireless connection, such as a connection conforming to any IEEE 802.11 protocol, where AP 106 would include Wi-Fi

router. In this example, AP 106 is shown connected to the Internet and not to the core network of the wireless system (described in further detail below).

RAN 110 may include one or more access nodes enabling connections 103 and 104 . These Access Nodes (ANs) may be referred to as Base Stations (BSs), NodeBs, Evolved NodeBs (eNBs), Next Generation NodeBs (gNBs), RAN nodes, etc., and may include terrestrial providing coverage within a geographic area (eg, cell) station (eg, terrestrial access point) or satellite station. RAN 110 may include one or more RAN nodes (eg, macro RAN node 111 ) for providing macro cells and for providing femto cells or pico cells (eg, having a smaller coverage area, more one or more RAN nodes (eg, low power (LP) RAN node 112) for cells with small user capacity or higher bandwidth).

Either of the RAN nodes 111 and 112 may terminate the air interface protocol and may be the first point of contact for the UEs 101 and 102 . In some embodiments, either of RAN nodes 111 and 112 may perform various logical functions of RAN 110, including but not limited to radio network controller (RNC) functions such as radio bearer management, uplink and downlink Dynamic radio resource management and data packet scheduling and mobility management.

According to some embodiments, UEs 101 and 102 may be configured to: according to various communication techniques such as, but not limited to, Orthogonal Frequency Division Multiple Access (OFDMA) communication techniques (eg, for downlink communication) or single carrier frequency division Multiple Access (SC-FDMA) communication technology (eg, for uplink and ProSe or sidelink communication), using Orthogonal Frequency Division Multiplexing (OFDM) communication signals to each other or to the RAN node 111 over a multi-carrier communication channel The scope of the embodiments is not limited to communicate with any of 112. The OFDM signal may include multiple orthogonal sub-carriers.

In some embodiments, a grid of downlink resources may be used for downlink transmissions from either of RAN nodes 111 and 112 to UEs 101 and 102, while uplink transmissions may utilize similar techniques. The grid may be a time-frequency grid called a resource grid or a time-frequency resource grid, which is the physical resource in each time slot in the downlink. This time-frequency plane representation is a common practice in OFDM systems, which makes radio resource allocation intuitive. Each column and row of the resource grid corresponds to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot in the radio frame. The smallest time-frequency units in the resource grid are called resource elements. Each resource grid includes a number of resource blocks, which describe the mapping of certain physical channels to resource elements. Each resource block includes a set of resource elements; in the frequency domain, this may represent the smallest amount of resources that can currently be allocated. There are several different physical downlink channels transmitted using such resource blocks.

The Physical Downlink Shared Channel (PDSCH) may carry user data and higher layer signaling to UEs 101 and 102 . The Physical Downlink Control Channel (PDCCH) may carry information about the transport format and resource allocation related to the PDSCH channel, among others. It can also inform UEs 101 and 102 of uplink shared channel related transport format, resource allocation and H-ARQ (Hybrid Automatic Repeat Request) information. In general, downlink scheduling (assignment of control channel resource blocks and shared the UE 102). Downlink resource assignment information may be sent on the PDCCH for (eg, assigned to) each of UEs 101 and 102.

The PDCCH may use control channel elements (CCEs) to convey control information. Before being mapped to resource elements, the PDCCH complex-valued symbols may first be organized into quads, which may then be arranged using a subblock interleaver for rate matching. Each PDCCH may be transmitted using one or more of these CCEs, where each CCE may correspond to nine groups of four physical resource elements called resource element groups (REGs). Four quadrature phase shift keying (QPSK) symbols can be mapped to each REG. The PDCCH may be transmitted using one or more CCEs, depending on the size of the downlink control information (DCI) and channel conditions. Four or more different PDCCH formats with different numbers of CCEs (eg, aggregation levels, L=1, 2, 4, or 8) may be defined in LTE.

Some embodiments may use concepts that are extensions of the above concepts for resource allocation for control channel information. For example, some embodiments may utilize an Enhanced Physical Downlink Control Channel (EPDCCH), which uses PDSCH resources for control information transmission. The EPDCCH may be transmitted using one or more enhanced control channel elements (ECCEs). Similar to above, each ECCE may correspond to nine groups of four physical resource elements called Enhanced Resource Element Groups (EREGs). In some cases, ECCEs can have other numbers of EREGs.

The RAN 110 is shown communicatively coupled to a core network (CN) 120 via an S1 interface 113 . In an embodiment, CN 120 may be an Evolved Packet Core (EPC) network, a Next Generation Packet Core (NPC) network, or some other type of CN. In this embodiment, the S1 interface 113 is divided into two parts: the S1-U interface 114, which carries traffic data between the RAN nodes 111 and 112 and the Serving Gateway (S-GW) 122; and the S1 Mobility Management Entity (MME) ) interface 115, which is the signaling interface between the RAN nodes 111 and 112 and the MME 121.

In this embodiment, CN 120 includes MME 121 , S-GW 122 , Packet Data Network (PDN) Gateway (P-GW) 123 and Home Subscriber Server (HSS) 124 . The MME 121 may be functionally similar to the control plane of the legacy service General Packet Radio Service (GPRS) Support Node (SGSN). The MME 121 may manage mobility aspects of access, such as gateway selection and tracking area list management. HSS 124 may include a database for network users, including subscription-related information used to support network entities in handling communication sessions. The CN 120 may include one or more HSSs 124, depending on the number of mobile subscribers, the capacity of the equipment, the organization of the network, and the like. For example, HSS 124 may provide support for routing/roaming, authentication, authorization, naming/addressing solutions, location dependencies, and the like.

S-GW 122 may terminate S1 interface 113 to RAN 110 and route data packets between RAN 110 and CN 120. Additionally, the S-GW 122 may be a local mobility anchor for inter-RAN node handover, and may also provide an anchor for inter-3GPP mobility. Other responsibilities can include legal interception, billing and some kind of policy enforcement.

The P-GW 123 may terminate the SGi interface to the PDN. P-GW 123 may route data packets between EPC network 123 and an external network (eg, a network including application server 130 (alternatively referred to as application function (AF))) via internet protocol (IP) interface 125 . In general, application server 130 may be an element that provides applications (eg, UMTS Packet Service (PS) domain, LTE PS data services, etc.) using IP bearer resources to the core network. In this embodiment, P-GW 123 is shown as being communicatively coupled to application server 130 via IP communication interface 125 . Application server 130 may also be configured to support one or more communication services for UEs 101 and 102 via CN 120 (eg, Voice over Internet Protocol (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc. ).

P-GW 123 may also be a node for policy enforcement and charging data collection. Policy and Charging Rules Function (PCRF) 126 is the policy and charging control element of CN 120 . In a non-roaming scenario, there may be a single PCRF associated with the UE's Internet Protocol Connectivity Access Network (IP-CAN) session in the Home Public Land Mobile Network (HPLMN). In a roaming scenario where services are off-premises, there may be two PCRFs associated with the UE's IP-CAN session: the home PCRF (H-PCRF) within the HPLMN and the visited PCRF (V-PCRF) within the visited public land mobile network (VPLMN). PCRF). PCRF 126 may be communicatively coupled to application server 130 via P-GW 123 . The application server 130 may signal the PCRF 126 to indicate the new service flow and select the appropriate quality of service (QoS) and charging parameters. PCRF 126 may provide this rule to a Policy and Charging Enforcement Function (PCEF) (not shown) with the appropriate Traffic Flow Template (TFT) and QoS Class Identifier (QCI), which initiates the QoS specified by Application Server 130 and billing.

The number of devices and/or networks shown in Figure 1 is for illustration purposes only. In practice, system 100 may include additional devices and/or networks; fewer devices and/or networks; different devices and/or networks; or devices and/or networks arranged differently than those shown in FIG. 1 . / or network. For example, although not shown, system 100 may include devices that facilitate or enable communications between the various components shown in system 100, such as routers, modems, gateways, switches, hubs, and the like. Alternatively or additionally, one or more devices of system 100 may perform one or more functions described as being performed by another device or devices of system 100 . Furthermore, the devices of system 100 may be interconnected with each other and/or with other devices via wired connections, wireless connections, or a combination of wired and wireless connections. In some embodiments, one or more devices of system 100 may be physically integrated within and/or may be physically attached to one or more other devices of system 100 . Furthermore, although a "direct" connection is shown between some of the devices of FIG. 1, in practice, some of the devices may communicate with each other via one or more additional devices and/or networks.

2 is a sequence flow diagram of an example process for packet forwarding during a handover procedure, where source and target nodes 111 use the same DRB(s) to communicate with UE 101 . As shown, the example of FIG. 2 may include UE 101, source node 111-1, and target node 111-2. Both the source node 111-1 and the target node 111-2 may be examples of the macro RAN node 111 or the LP RAN node 112 described above with reference to FIG. 1 . The example of FIG. 2 is provided as a non-limiting example. Indeed, the example of FIG. 2 may include fewer, additional, and/or alternative operations or functions, such as one or more of the operations or functions in FIGS. 3-6 . Additionally, one or more of the operations or functions of FIG. 2 may be performed by fewer, additional, or alternative devices, which may include one or more of the devices described above with reference to FIG. 1 .

As shown, UE 101 and source node 111-1 may transmit packets to each other (route 205). As described herein, packets may include PDUs transmitted between devices (eg, UE 101, source node 111-1, target node 111-2, devices of CN 120, etc.) over the user plane of the wireless communication network. Such packets may be referred to herein as user data (UD). Both the UE 101 and the source node 111-1 may implement a protocol such as PDCP to assign an SN to each packet. The SN may be included in the packet at a location reserved for SN information. For example, the SN may be 12 bits in length and may occupy bits 4-8 of the first octet of the packet, and all 8 bits of the second octet of the packet. In this embodiment, the first bit of the first octet may be dedicated to indicating whether the packet corresponds to user data or control data, and the second, third and fourth bits of the first octet may be reserved for other purposes. In some embodiments, the grouping may be configured in different ways.

Source node 111-1 may receive packets intended for UE 101 (from CN 120) and may temporarily store the packets in a local buffer memory of source node 111-1. Before sending the packets to the UE 101, the source node 111-1 may assign a SN to each packet. According to PDCP, the SN assigned to each packet may be based on the DRB used by the source node 111-1 to send the packet to the UE 101. The SNs of the packets may be assigned in a relative order (eg, 1, 2, 3, etc.) consistent with the manner (eg, order) in which the packets are to be sent, received, read, and/or processed by the UE 101 . When sending packets to UE 101, source node 111-1 can monitor which packets have been sent (and when) and whether UE 101 has acknowledged any sent packets. When the UE 101 indicates that one or more packets were not received, the source node 111-1 may resend the identified packets, record the time of the resend, and continue to monitor whether the UE 101 acknowledges the resent packets. When the buffered packet is acknowledged by the UE 101, the source node 111-1 may (immediately or periodically) remove the packet from the buffer.

The SN may be assigned by the PDCP layer of the protocol stack implemented by the source node 111-1. In such an embodiment, the PDCP layer may operate above the radio link control (RLC) layer of the protocol stack, the RLC layer may operate above the medium access control (MAC) layer of the protocol stack, and the MAC layer may be in the Operates above the physical (PHY) layer of the protocol stack. UE 101 may implement similar protocol stacks (eg, PDCP layer, RLC layer, MAC layer, and PHY layer), and may transmit, process, and receive packets in a manner similar to source node 111-1. In some embodiments, source node 111-1 may assign SNs to packets before and during the handover procedure. In some embodiments, the source node 111-1 may start assigning SNs to packets only after determining that the UE 101 is to be handed over to another RAN node 111.

Assume that the source node 111-1 determines that the UE 101 should undergo a handover procedure involving the target node 111-2 (block 210). In response, source node 111-1 may stop sending user data packets to UE 101 and determine which buffered packets to send to target node 111-2. In some embodiments, the source node 111-1 may determine that the packets to be sent to the target node 111-2 include all packets sent to the UE 101 measured from the oldest packet still unacknowledged by the UE 101. For example, if source node 111-1 sends packets 1-10 to UE 101, and UE 101 has acknowledged receipt of packets 1-3 and 6-7 (but not 4, 5, or 8-10), then because packets 4 is the oldest packet still unacknowledged by UE 101, so the target node can determine that packet 4-10 is to be sent to target node 111-2. In contrast, in some embodiments, source node 111-1 may determine that packets to be sent to target node 111-2 only include packets that have not been acknowledged by UE 101. For example, continuing the example where source node 111-1 sends packets 1-10 to UE 101, and UE 101 has acknowledged receipt of packets 1-3 and 6-7 (but not 4, 5, or 8-10), then Since packets 1-3 and 6-7 have been acknowledged by UE 101, the target node can determine to send only packets 4, 5 and 8-10 to target node 111-2.

The source node 111-1 may transmit the determined packet to the destination node 111-2 (route 220). As shown, each packet may include a corresponding SN and DRB ID. The DRB ID may indicate the DRB that the source node 111-1 will use to determine the SN and that the source node 111-1 will use to send packets to the UE 101 . In some embodiments, source node 111-1 may only insert the DRB ID into packets transmitted by target node 111-2 to UE 101 (eg, after source node 111-1 determines to perform a handover procedure). In some embodiments, source node 111-1 may include the DRB ID in all packets directed to UE 101 (eg, packets received even before source node 111-1 determines to perform a handover procedure). Target node 111-2 may buffer each packet and map each packet to a corresponding DRB based on the DRB ID associated with each packet (block 225). Additionally, the target node 111-2 may assign the same DRB as the source node 111-1 used to send the packet to the UE 101 based on the DRB ID (block 230). As such, target node 111-2 may transmit the packet to UE 101 using the same DRB as source node 111-1 (route 255).

The source node 111-1 may notify the UE 101 of the HO procedure (route 235) by sending an RRC connection reconfiguration request message to the UE 101, which may include configuration information for establishing a connection with the target node 111-2. In some embodiments, UE 101 may respond to the message from source node 111-1 by, for example, detaching from source node 111-1 and transmitting an RRC connection reconfiguration complete message to target node 111-2, examples of which are described below with reference to Figures 5 and 6 are described in detail.

In embodiments where (as described above) the source node 111-1 is configured to determine that the packets to be sent to the target node 111-2 comprise all packets sent to the UE 101 since the oldest packet not yet acknowledged by the UE 101, The UE 101 may operate similarly by dropping packets based on the oldest packet sent by the source node 111-1 that the UE 101 has not successfully received (and therefore not acknowledged) (block 240). For example, if source node 111-1 sends packets 1-10 to UE 101, and UE 101 only receives packets 1-3 and 6-7 (but not 4, 5 or 8-10), then because packet 4 is the UE The oldest packet that 101 has not yet received/acknowledged, so UE 101 may discard packets 4-10. Doing so may free up storage capacity for UE 101, since in such an embodiment, target node 111-2 may be configured to resend packets (eg, packets 4-10) starting with the oldest, unacknowledged packet. In contrast, sending only unacknowledged packets (eg, packets 4, 5, and 8-10) at source node 111-1 to destination node 111-2 allows destination node 111-2 to send only unacknowledged packets In embodiments to UE 101, UE 101 may process packets (eg, packets 1-3 and 6-7) successfully received from source node 111-1 and send them to upper layers (eg, IP layer or another type of Layer 3 protocol), etc., without waiting for lost packets (eg, packets 4, 5, and 8-10) from target node 111-2 (block 245).

After the target node 111-2 has successfully sent the packet to the UE 101, the UE 101, the source node 111-1 and the target node 111-2 may complete the HO procedure. Doing so may include one or more of various operations (such as UE 101 detaching from source node 111-1 and transmitting an RRC connection reconfiguration complete message to target node 111-2) (route 250). A detailed example of such an operation is described below with reference to FIGS. 5 and 6 . Target node 111-2 may send the data packet to UE 101 (route 255). In some embodiments, target node 111-2 may send to UE 101 all data packets received by target node 111-2 from source node 111-1 (route 220). In some embodiments, before the target node 111-2 sends the data packet to the UE 101, the UE 101 may send to the target node 111-2 one or more data that the target node 111-2 has received from the source node 111-1 acknowledgment message for the packet, and the target node 111-2 may send to the UE 101 only data packets for which an acknowledgment has not been received (ie, unacknowledged packets).

In some embodiments, the UE 101 may notify the target node 111-2 when all data packets (eg, all packets with SNs from the source node) have been received. In some embodiments, this notification or indication may be provided by the UE 101 via an end marker packet or another type of indicator. Additionally or alternatively, after UE 101 has successfully received the packet from target node 111-2 (route 255), target node 111-2 may reconfigure the DRB for communicating with UE 101 (block 260). For example, the DRB set by the source node 111-1 to communicate with the UE 101 may not be the best or preferred DRB for the target node 111-2 to communicate with the UE 101. As such, after a packet from source node 111-1 has been successfully received by UE 101, target node 111-2 may reconfigure (eg, reassign, reallocate, etc.) DRBs of user data are transmitted to each other (block 260). In some embodiments, target node 111-2 may perform these operations at an earlier time. For example, before transmitting the data packet to UE 101 (route 255), target node 111-2 may determine the DRB to be used by target node 111-2 after transmitting the data packet to UE 101 (eg, after the HO procedure is completed) , and after the UE 101 has received the data packet (eg, after the HO procedure is completed), the target node 111-2 may provide the UE 101 with configuration information for using the new DRB.

3 is a sequence flow diagram of an example process for packet forwarding based on QoS IDs during a handover process. As shown, the example of FIG. 3 may include UE 101, source node 111-1, and target node 111-2. Both the source node 111-1 and the target node 111-2 may be examples of the macro RAN node 111 or the LP RAN node 112 described above with reference to FIG. 1 . The example of FIG. 3 is provided as a non-limiting example. In practice, the example of FIG. 3 may include fewer, additional and/or alternative operations or functions, such as one or more of the operations or functions in FIGS. 2 and 4-6. Additionally, one or more of the operations or functions of FIG. 3 may be performed by fewer, additional, or alternative devices, which may include one or more of the devices described above with reference to FIG. 1 .

As shown, UE 101 and source node 111-1 may transmit user data packets to each other over the user plane (route 305). Both UE 101 and source node 111-1 may implement a protocol to assign a SN to each packet. Instead of the per-packet SN being based on the DRB used to transport the packet, the per-packet SN may be based on the QoS flow associated with the packet. The QoS flow associated with the packet may be determined or identified based on a QoS flow filter or QoS indicator or other QoS marking information included in the packet. This information may also or alternatively be transmitted over the radio protocol, in the user plane or as part of the configuration information exchanged between the UE 101 and the CN 120. Since the SN may be based on QoS flows associated with packets (rather than, eg, DRBs), one DRB may be used to transport user data packets corresponding to multiple different numbering sequences.

Assume that source node 111-1 determines that UE 101 will undergo a HO procedure involving target node 111-2 (block 310). In response, source node 111-1 may stop sending packets of user data to UE 101 and determine which buffered packets to send to target node 111-2. In some embodiments, source node 111-1 may determine that the packets to be sent to target node 111-2 include all packets sent to UE 101 since the oldest packet still unacknowledged by UE 101. For example, if source node 111-1 sends packets 1-10 to UE 101, and UE 101 has acknowledged receipt of packets 1-3 and 6-7 (but not 4, 5, or 8-10), then because packets 4 is the oldest packet still unacknowledged by UE 101, so target node 111-2 can determine that packet 4-10 is to be sent to target node 111-2. In contrast, in some embodiments, source node 111-1 may determine that packets to be sent to target node 111-2 only include packets that have not been acknowledged by UE 101. For example, continuing with the example where source node 111-1 sends packets 1-10 to UE 101, and UE 101 has acknowledged receipt of packets 1-3 and 6-7 (but not 4, 5, or 8-10), Then since packets 1-3 and 6-7 have been acknowledged by UE 101, target node 111-2 can determine to send only packets 4, 5 and 8-10 to target node 111-2.

The source node 111-1 may notify the UE 101 of the HO procedure (route 320) by sending an RRC connection reconfiguration request message to the UE 101, which may include configuration information for establishing a connection with the target node 111-2. The configuration information may include instructions as to which packet forwarding technique the source and target nodes 111 are implementing (eg, whether the target node 111-2 is only forwarding unacknowledged packets, etc.). Packet forwarding techniques may inform UE 101 which packets are expected from target node 111-2. In some embodiments, UE 101 may respond to the message from source node 111-1 by, for example, detaching from source node 111-1 and transmitting an RRC connection reconfiguration complete message to target node 111-2, examples of which are described below with reference to Figures 5 and 6 are described in detail.

In embodiments where (as described above) the source node 111-1 is configured to determine that the packets to be sent to the target node 111-2 comprise all packets sent to the UE 101 since the oldest packet not yet acknowledged by the UE 101, The UE 101 may operate similarly by dropping packets based on the oldest packet sent by the source node 111-1 that the UE 101 has not successfully received (and therefore not acknowledged) (block 325). For example, if source node 111-1 sends packets 1-10 to UE 101, and UE 101 only receives packets 1-3 and 6-7 (but not 4, 5 or 8-10), then because packet 4 is the UE The oldest packet that 101 has not yet received/acknowledged, so UE 101 may discard packets 4-10. Doing so may free up storage capacity for UE 101, since in such an embodiment, target node 111-2 may be configured to resend packets (eg, packets 4-10) starting with the oldest, unacknowledged packet. In contrast, sending only unacknowledged packets (eg, packets 4, 5, and 8-10) at source node 111-1 to destination node 111-2 allows destination node 111-2 to send only unacknowledged packets In embodiments to UE 101, UE 101 may process packets (eg, packets 1-3 and 6-7) successfully received from source node 111-1 and send them to upper layers (eg, IP layer or another type of Layer 3 protocol), etc., without waiting for lost packets (eg, packets 4, 5, and 8-10) from target node 111-2 (block 330).

The source node 111-1 may transmit the user data packet to the destination node 111-2 (route 335). As shown, each packet may include a corresponding SN and QoS flow ID. Target node 111-2 may buffer each packet and map each packet to a corresponding QoS flow ID based on the QoS flow ID already associated with each packet (block 340). Additionally, target node 111-2 may determine and assign a preferred DRB for sending data user packets to UE 101 (block 345). Compared to the example of FIG. 2 , the target node 111 - 2 may select a different set of DRBs than the source node 111 - 1 uses to transmit user data packets to the UE 101 .

The UE 101, the source node 111-1 and the target node 111-2 can complete the HO procedure. Doing so may include one or more of various operations (such as UE 101 detaching from source node 111-1 and transmitting an RRC connection reconfiguration complete message to target node 111-2) (route 350). A detailed example of such an operation is described below with reference to FIGS. 5 and 6 . Target node 111-2 may send the user data packet to UE 101 (on route 355). In the event that the UE 101 fails to successfully receive one or more of the transmitted packets, the UE 101 may send a resend request for the failed packet to the target node 110, and the target node 111-2 may respond by resending the failed packet (Route 360).

Figure 4 is a sequential flow diagram of an example process for packet forwarding during a handover procedure, where the source and target nodes 111 use different DRBs. As shown, the example of FIG. 4 may include UE 101, source node 111-1 and target node 111-2, all of which may be examples of macro RAN node 111 or LP RAN node 112 described above with reference to FIG. The example of FIG. 4 is provided as a non-limiting example. Indeed, the example of FIG. 4 may include fewer, additional and/or alternative operations or functions, such as one or more of the operations or functions of FIGS. 2 , 3 , 5 and 6 . Additionally, one or more of the operations or functions of FIG. 4 may be performed by fewer, additional, or alternative devices, which may include one or more of the devices described above with reference to FIG. 1 .

As shown, UE 101 and source node 111-1 may transmit packets to each other (route 405). For example, source node 111-1 may receive packets (from CN 120) intended for UE 101 and may temporarily store the packets in a local buffer memory of source node 111-1. Before sending the packets to the UE 101, the source node 111-1 may assign a SN to each packet. According to PDCP, the SN assigned to each packet may be based on the DRB used by the source node 111-1 to send the packet to the UE 101. The SNs of the packets may be assigned in an order consistent with the manner in which the packets are to be received, read, and/or processed by the UE 101 . When sending packets to UE 101, source node 111-1 can monitor which packets have been sent (and when) and whether UE 101 has acknowledged any sent packets. When the UE 101 indicates that one or more packets were not received, the source node 111-1 may resend the identified packets, record the time of the resend, and continue to monitor whether the UE 101 acknowledges the resent packets. When the buffered packet is acknowledged by the UE 101, the source node 111-1 may (immediately or periodically) remove the packet from the buffer.

Assume that the source node 111-1 determines that the UE 101 should undergo a handover procedure involving the target node 111-2 (block 410). In response, source node 111-1 may stop sending packets of user data to UE 101 and determine which buffered packets to send to target node 111-2. In some embodiments, source node 111-1 may determine that the packets to be sent to target node 111-2 include all packets sent to UE 101 measured starting with the oldest packet still unacknowledged by UE 101. For example, if source node 111-1 sends packets 1-10 to UE 101, and UE 101 has acknowledged receipt of packets 1-3 and 6-7 (but not 4, 5, or 8-10), then because packets 4 is the oldest packet still unacknowledged by UE 101, so target node 111-2 can determine that packet 4-10 is to be sent to target node 111-2. In contrast, in some embodiments, source node 111-1 may determine that packets to be sent to target node 111-2 only include packets that have not been acknowledged by UE 101. For example, continuing with the example where source node 111-1 sends packets 1-10 to UE 101, and UE 101 has acknowledged receipt of packets 1-3 and 6-7 (but not 4, 5, or 8-10), Then since packets 1-3 and 6-7 have been acknowledged by UE 101, target node 111-2 can determine to send only packets 4, 5 and 8-10 to target node 111-2.

The source node 111-1 may transmit the determined packet to the destination node 111-2 (route 420). As shown, each packet may include a corresponding SN and DRB ID. The DRB ID may indicate the DRB that the source node 111-1 will use to determine the SN and that the source node 111-1 will use to send packets to the UE 101 . The source node 111-1 may notify the UE 101 of the HO procedure (route 425) by sending an RRC connection reconfiguration request message to the UE 101, which may include configuration information for establishing a connection with the target node 111-2.

In some embodiments, where the source node 111-1 is configured to determine that the packets to be sent to the target node 111-2 include all packets sent to the UE 101 since the oldest packet not yet acknowledged by the UE 101, the UE 101 may pass Operates similarly (block 430), dropping packets based on the oldest packet sent by source node 111-1 that UE 101 has not successfully received (and therefore not acknowledged). For example, if source node 111-1 sends packets 1-10 to UE 101, and UE 101 only receives packets 1-3 and 6-7 (but not 4, 5, or 8-10), then because packet 4 is The oldest packet that UE 101 has not yet received/acknowledged, so UE 101 may discard packets 4-10. In contrast, sending only unacknowledged packets (eg, packets 4, 5, and 8-10) at source node 111-1 to destination node 111-2 allows destination node 111-2 to send only unacknowledged packets In embodiments to UE 101, UE 101 may process packets (eg, packets 1-3 and 6-7) successfully received from source node 111-1 and send them to upper layers (eg, IP layer or another type of Layer 3 protocol), etc., without waiting for lost packets (eg, packets 4, 5, and 8-10) from target node 111-2 (block 435).

In response to receiving the packets from source node 111-1, target node 111-2 may buffer each packet and determine a DRB for forwarding the packet to UE 101 (block 440). As such, the DRB used by the target node 111-2 may be different from the DRB used by the source node 111-1. Additionally, enabling target node 111-2 to assign, determine, and use a preferred DRB at this point in the HO procedure may mitigate target node 111-2 switching DRBs later (eg, after the HO procedure), as described above with reference to FIG. 2 stated.

Additionally, target node 111-2 may determine a new SN for the packet based on the newly determined DRB, and assign the new SN to each packet (block 445). In some embodiments, for each packet, target node 111-2 may map (eg, create a record) the SN (and/or DRB) of source node 111-1 with the new SN (and/or DRB) from target node 111-2. / or DRB). Doing so may enable target node 111-2 to ensure that the packet is successfully sent to UE 101, which may involve an acknowledgment message from UE 101, retransmission from target node 111-2. As part of the HO procedure, the UE 101 may transmit an RRC connection reconfiguration complete message to the target node 111-2 (route 450), and the target node 111-2 may transmit the packet to the UE using the same DRB as the source node 111-1 101 (block 455). In the event that the UE 101 does not successfully receive one or more of the transmitted packets, the UE 101 may send a resend request for the failed packet to the target node 110, and the target node 111-2 may respond by resending the failed packet (Route 460).

5 and 6 are sequence flow diagrams of examples of detailed procedures for packet forwarding during a handover procedure. As shown, the example of FIG. 5 may include UE 101 , source node 111 - 1 , target node 111 - 2 , SGW 112 and user plane function device(s) 510 .

Both the source node 111-1 and the target node 111-2 may be examples of the macro RAN node 111 or the LPRAN node 112 described above with reference to FIG. 1 . Similarly, SGW 122 may be an example of S-GW 122 of FIG. 1 . The user plane function device(s) 510 may comprise one or more server devices implementing the user plane functions (as opposed to eg control plane functions) of the 5G (or next generation (NG)) CN. Depending on the embodiment, the SGW 122 and the user plane function device(s) 510 may correspond to the same CN or different CNs. For example, SGW 122 may correspond to an EPC supporting source node 111-1, while user plane functional device(s) 510 may correspond to a 5G CN supporting target node 111-2.

The examples of FIGS. 5 and 6 are provided as non-limiting examples. In practice, the examples of FIGS. 5 and 6 may include fewer, additional and/or alternative operations or functions, such as one or more of the operations or functions of FIGS. 2-4 . Additionally, one or more of the operations or functions in FIGS. 5 and 6 may be performed by fewer, additional, or alternative devices, which may include one or more of the devices described above with reference to FIG. 1 .

Referring to Figure 5, UE 101 may send and receive information to and from CN 120 via the connection with source node 111-1 (route 505). Information can be transmitted through the User Data (UD) plane. For example, source node 111-1 may receive packets (from CN 120) intended for UE 101 and may temporarily store the packets in a local buffer memory of source node 111-1. Before sending the packets to the UE 101, the source node 111-1 may assign a SN to each packet. According to PDCP, the SN assigned to each packet may be based on the DRB that the source node 111-1 may use to send the packet to the UE 101. The SNs of the packets may be assigned in an order consistent with the manner in which the packets are to be received, read, and/or processed by the UE 101 . When sending packets to UE 101, source node 111-1 can monitor which packets have been sent (and when) and whether UE 101 has acknowledged any sent packets. When the UE 101 indicates that one or more packets were not received, the source node 111-1 may resend the identified packets, record the time of the resend, and continue to monitor whether the UE 101 acknowledges the resent packets. When the buffered packet is acknowledged by the UE 101, the source node 111-1 may (immediately or periodically) remove the packet from the buffer.

Assume that source node 111-1 determines that UE 101 should undergo a handover procedure involving target node 111-2 (block 510). In response, source node 111-1 may stop sending packets of user data to UE 101 and determine which buffered packets to send to target node 111-2. In some embodiments, source node 111-1 may determine that the packets to be sent to target node 111-2 include all packets sent to UE 101 measured starting with the oldest packet still unacknowledged by UE 101. For example, if source node 111-1 sends packets 1-10 to UE 101, and UE 101 has acknowledged receipt of packets 1-3 and 6-7 (but not 4, 5, or 8-10), then because packets 4 is the oldest packet still unacknowledged by UE 101, so target node 111-2 can determine that packet 4-10 is to be sent to target node 111-2. In contrast, in some embodiments, source node 111-1 may determine that packets to be sent to target node 111-2 only include packets that have not been acknowledged by UE 101. For example, continuing with the example where source node 111-1 sends packets 1-10 to UE 101, and UE 101 has acknowledged receipt of packets 1-3 and 6-7 (but not 4, 5, or 8-10), Then since packets 1-3 and 6-7 have been acknowledged by UE 101, target node 111-2 can determine to send only packets 4, 5 and 8-10 to target node 111-2.

Source node 111-1 may send a Layer 3 (L3) HO request to target node 111-2 (route 515). The request may include DRB mapping information, which may include an indication of the UE 101 and the DRB used by the source node 111 - 1 to communicate with the UE 101 . In response, target node 111-2 may perform admission control operations (block 520), which may include determining whether to accept or reject the HO request. This determination may be based on various factors, such as the availability of radio resources to communicate with the UE 101, the congestion level associated with the target node 111-2, and the like. Assume that the target node 111-2 determines to accept the HO request. As shown, target node 111-2 may respond to source node 111-1 by transmitting an L3 HO request acknowledgement message (route 525), and in response, source node 111-1 may send UE 101 an L3 RRC connection reconfiguration message . (Route 530). The L3 RRC connection reconfiguration message may include mobility control information, which may include instructions for the UE 101 to communicate with the target node 111-2.

In response to the L3 RRC connection reconfiguration message, the UE 101 may detach from the source node 111-1 and synchronize to the target node 111-2 (block 535). In some embodiments, where the source node 111-1 is configured to determine that the packets to be sent to the target node 111-2 include all packets sent to the UE 101 since the oldest packet not yet acknowledged by the UE 101, the UE 101 may pass Operates similarly (block 540), dropping packets based on the oldest packet sent by source node 111-1 that UE 101 has not successfully received (and therefore not acknowledged). For example, if source node 111-1 sends packets 1-10 to UE 101, and UE 101 only receives packets 1-3 and 6-7 (but not 4, 5, or 8-10), then because packet 4 is The oldest packet that UE 101 has not yet received/acknowledged, so UE 101 may discard packets 4-10. In contrast, sending only unacknowledged packets (eg, packets 4, 5, and 8-10) at source node 111-1 to destination node 111-2 allows destination node 111-2 to send only unacknowledged packets In embodiments to UE 101, UE 101 may process packets (eg, packets 1-3 and 6-7) successfully received from source node 111-1 and send them to upper layers (eg, IP layer or another type of Layer 3 protocol), etc., without waiting for lost packets (eg, packets 4, 5, and 8-10) from target node 111-2 (block 545).

Source node 111-1 may send L3 SN state transition information (route 550) to target node 111-2, which may include communication standard information for performing the handover procedure. The source node 111-1 may send the UD packet data for forwarding purposes to the target node 111-2 (route 555). As mentioned above, this may include all buffered packets sent to UE 101 since the oldest packet still unacknowledged by UE 101 (eg, packets 1-3 and 6-7 instead of 4, 5 or 8-10). Alternatively, this may include only packets buffered by source node 111-1 and not acknowledged by UE 101 (eg, packets 4, 5 and 8-10 instead of 1-3, 6 and 7). Upon receipt of the packet from source node 111-1, target node 111-2 may buffer the packet (eg, for processing and/or subsequent transmission to UE 101).

Depending on the embodiment, the target node 111-2 may process the received packets based on the packet data forwarding technique being implemented. For example, target node 111-2 may map and/or assign the packet to the same DRB used by source node 111-1 to send the packet to UE 101 (see, eg, FIG. 2). Alternatively, the target node may map the received packet to the QoS used by the source node 111-1 to send the packet to the UE 101, and then assign the received packet to the DRB preferred by the target node 111-2 (which may is the same or a different DRB than the DRB used by the source node 111-1 to send the packet to the UE 101) (see eg, Figure 3). Yet another alternative, the target node 111-2 may determine and assign a preferred DRB for forwarding the packet to the UE 101 (which may be the same or different than the DRB used by the source node 111-1 to send the packet to the UE 101). DRB), assign (eg, insert) a new SN to the packet based on the determined DRB, and for each received packet, create a mapping of the SN assigned by the source node 111-1 to the new SN assigned by the target node 111-2 A record of the SN (see eg, Figure 4).

Referring now to Figure 6, based on the RRC connection reconfiguration message from source node 111-1, UE 101 may reconfigure itself for the handover procedure and send an L3 RRC connection reconfiguration complete message to target node 111-2 (route 605). In response, target node 111-2 and UE 101 may transmit user data packets to each other (route 610). For example, the target node 111-2 may forward packets received from the source node 111-1 to the UE 101 in the downlink (DL) direction. Additionally or alternatively, the UE 101 may send the packet to the target node 111-2 in the uplink (UL) direction. Target node 111-2 may process packets received from UE 101 and/or forward packets received from UE 101 to SGW 122 of target node 111-2 (route 615).

The target node 111-2 may also send an L3 path switch request message (route 620) to the user plane function device(s) 510, and the user plane function device(s) 510 may send an L3 modify bearer request message to the SGW 122. Respond (Route 625). These messages may enable/cause the equipment of CN 120 to switch to the DL path for transmitting packets to UE 101 via target node 111-2 according to the handover procedure. Additionally, in response to the L3 Modify Bearer Response message, the SGW 112 may switch the DL path information (eg, information indicating the DL path from the CN 120 to the UE 101) based on the handover procedure (eg, including the target node 111-2), and may transfer the UD An end marker packet is sent to source node 111-1 (block and route 630). The end marker packet may include an indication of the last packet for UE 101 provided by CN 120 to source node 111-1.

Source node 111-1 may forward the UD end marker packet to destination node 111-2 (route 635), and destination node 111-2 and SGW 122 may transmit the packet to each other (route 640). The UD end marker packet may inform the target node 111-2 of the last packet for the UE 101 provided by the CN 120 to the source node 111-1. As such, destination node 111-2 can use the end marker packet to determine whether the packet from source node 111-1 includes the last packet sent from CN 120 to source node 111-1, and/or received by destination node 111-2 from CN 120 Whether subsequent packets for UE 101 start with end marker packets (eg, whether packets provided from CN 120 in the DL direction are lost during the handover procedure). If/when target node 111-2 determines that a packet from CN 120 has been lost, target node 111-2 may request retransmission of the lost packet.

SGW 122 may send an L3 Modify Bearer Response message to user plane function device(s) 510 (route 645), which may correspond to the previous L3 Modify Bearer Request message (see route 625). In response, user plane functional device(s) 510 may send an L3 path handover request confirmation message to target node 111-2 (route 650), which may correspond to the previous L3 handover request message (see route 620). In turn, the target node 111-2 may send the L3 UE context release message to the source node 111-1 (route 655), and the source node 111-1 may communicate with the UE 101 by releasing the radio resources to respond (block 660).

As used herein, the terms "circuit," "processing circuit," or "logic" may refer to, being part of, or including an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and and/or memory (shared, dedicated or grouped) executing one or more software or firmware programs, combinational logic circuits, and/or other suitable hardware components that provide the described functionality. In some embodiments, a circuit may be implemented in one or more software or firmware modules, or functionality associated with a circuit may be implemented in one or more software or firmware modules. In some embodiments, a circuit may include logic that is at least partially operable in hardware.

The embodiments described herein may be implemented in a system using any suitably configured hardware and/or software. FIG. 7 illustrates example components of a device 700 in accordance with some embodiments. In some embodiments, device 700 may include application circuitry 702, baseband circuitry 704, radio frequency (RF) circuitry 706, front end module (FEM) circuitry 708, one or more antennas 710, and power management circuitry (PMC) 712, at least as coupled together as shown. The illustrated components of apparatus 700 may be included in a UE or a RAN node. In some embodiments, the apparatus 700 may include fewer elements (eg, the RAN node may not utilize the application circuit 702, but instead include a processor/controller to process IP data received from the EPC). In some embodiments, device 700 may include additional elements, such as memory/storage, display, camera, sensors, or input/output (I/O) interfaces. In other embodiments, the components described below may be included in more than one device (eg, for cloud RAN (C-RAN) implementations, the circuits may be included separately in more than one device).

Application circuitry 702 may include one or more application processors. For example, application circuitry 702 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. A processor may include any combination of general-purpose processors and special-purpose processors (eg, graphics processors, application processors, etc.). The processor may be coupled to or include memory/storage, and may be configured to execute instructions stored in the memory/storage to enable various applications or operating systems to run on device 700 . In some embodiments, the processor of the application circuit 702 may process IP data packets received from the EPC.

Baseband circuitry 704 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. Baseband circuitry 704 may include one or more baseband processors or control logic to process baseband signals received from the receive signal path of RF circuitry 706 and generate baseband signals for the transmit signal path of RF circuitry 706 . Baseband circuitry 704 may interface with application circuitry 702 for generating and processing baseband signals and controlling the operation of RF circuitry 706 . For example, in some embodiments, the baseband circuitry 704 may include a third generation (3G) baseband processor 704A, a fourth generation (4G) baseband processor 704B, a fifth generation (5G) baseband processor 704C, or for other existing There are other baseband processors 704D of a generation, a generation in development, or a generation to be developed in the future (eg, second generation (2G), sixth generation (6G), etc.). Baseband circuitry 704 (eg, one or more of baseband processors 704A-D) may handle various radio control functions that enable communication via RF circuitry 706 with one or more radio networks. In other embodiments, some or all of the functions of baseband processors 704A-D may be included in modules stored in memory 704G and executed via central processing unit (CPU) 704E. Radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, and the like. In some embodiments, the modulation/demodulation circuitry of baseband circuitry 704 may include Fast Fourier Transform (FFT), precoding, or constellation mapping/demapping functionality. In some embodiments, the encoding/decoding circuitry of baseband circuitry 704 may include convolution, tail-biting convolution, turbo, Viterbi, or low density parity check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functions are not limited to these examples, and other suitable functions may be included in other embodiments.

In some embodiments, baseband circuitry 704 may include one or more audio digital signal processors (DSPs) 704F. Audio DSP 704F may include elements for compression/decompression and echo cancellation, and may include other suitable processing elements in other embodiments. In some embodiments, the components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or provided on the same circuit board. In some embodiments, some or all of the constituent components of the baseband circuit 704 and the application circuit 702 may be implemented together, eg, on a system on a chip (SOC).

In some embodiments, baseband circuitry 704 may provide communications compatible with one or more radio technologies. For example, in some embodiments, baseband circuitry 704 may support communication with an Evolved Universal Terrestrial Radio Access Network (EUTRAN) or other Wireless Metropolitan Area Network (WMAN), Wireless Local Area Network (WLAN), Wireless Personal Area Network (WPAN). Embodiments in which the baseband circuit 704 is configured to support radio communications of more than one wireless protocol may be referred to as a multimode baseband circuit.

RF circuitry 706 may use modulated electromagnetic radiation through a non-solid medium to enable communication with a wireless network. In various embodiments, RF circuitry 706 may include switches, filters, amplifiers, etc. to facilitate communication with wireless networks. RF circuitry 706 may include a receive signal path, which may include circuitry for downconverting RF signals received from FEM circuitry 708 and providing baseband signals to baseband circuitry 704 . RF circuit 706 may also include a transmit signal path, which may include circuitry for upconverting the baseband signal provided by baseband circuit 704 and providing the RF output signal to FEM circuit 708 for transmission.

In some embodiments, the receive signal path of RF circuit 706 may include mixer circuit 706A, amplifier circuit 706B, and filter circuit 706C. In some embodiments, the transmit signal path of RF circuit 706 may include filter circuit 706C and mixer circuit 706A. The RF circuit 706 may also include a synthesizer circuit 706D for synthesizing the frequencies used by the mixer circuit 706A of the receive signal path and the transmit signal path. In some embodiments, the mixer circuit 706A of the receive signal path may be configured to downconvert the RF signal received from the FEM circuit 708 based on the synthesis frequency provided by the synthesizer circuit 706D. Amplifier circuit 706B may be configured to amplify the down-converted signal, and filter circuit 706C may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signal to generate the output baseband signal. The output baseband signal may be provided to baseband circuitry 704 for further processing. In some embodiments, the output baseband signal may be a zero frequency baseband signal, but this is not a requirement. In some embodiments, the mixer circuit 706A of the receive signal path may comprise a passive mixer, although the scope of embodiments is not limited in this regard.

In some embodiments, the mixer circuit 706A of the transmit signal path may be configured to upconvert the input baseband signal based on the synthesis frequency provided by the synthesizer circuit 706D to generate the RF output signal for the FEM circuit 708 . The baseband signal may be provided by baseband circuit 704 and may be filtered by filter circuit 706C.

In some embodiments, the mixer circuit 706A of the receive signal path and the mixer circuit 706A of the transmit signal path may include two or more mixers, and may be arranged for quadrature down-conversion and up-conversion, respectively frequency conversion. In some embodiments, the mixer circuit 706A of the receive signal path and the mixer circuit 706A of the transmit signal path may include two or more mixers, and may be arranged for image rejection (eg, Hartley image inhibition). In some embodiments, the mixer circuit 706A of the receive signal path and the mixer circuit 706A of the transmit signal path may be arranged for direct downconversion and direct upconversion, respectively. In some embodiments, the mixer circuit 706A of the receive signal path and the mixer circuit 706A of the transmit signal path may be configured for superheterodyne operation.

In some embodiments, the output baseband signal and the input baseband signal may be analog baseband signals, although the scope of embodiments is not limited in this regard. In some alternative embodiments, the output baseband signal and the input baseband signal may be digital baseband signals. In these alternative embodiments, RF circuitry 706 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuits, and baseband circuitry 704 may include a digital baseband interface to communicate with RF circuitry 706 .

In some dual-mode embodiments, separate radio IC circuits may be provided for processing signals in each spectrum, although the scope of embodiments is not limited in this regard.

In some embodiments, synthesizer circuit 706D may be a fractional-N synthesizer or a fractional N/N+1 synthesizer, although the scope of embodiments is not limited in this regard, as other types of frequency synthesizers may be suitable. For example, synthesizer circuit 706D may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer including a phase locked loop with frequency dividers.

Synthesizer circuit 706D may be configured to synthesize an output frequency for use by mixer circuit 706A of RF circuit 706 based on the frequency input and the divider control input. In some embodiments, synthesizer circuit 706D may be a fractional N/N+1 synthesizer.

In some embodiments, the frequency input may be provided by a voltage controlled oscillator (VCO), but this is not a requirement. The divider control input may be provided by the baseband circuit 704 or the application processor 702, depending on the desired output frequency. In some embodiments, the divider control input (eg, N) may be determined from a lookup table based on the channel indicated by the application processor 702 .

The synthesizer circuit 706D of the RF circuit 706 may include a divider, a delay locked loop (DLL), a multiplexer, and a phase accumulator. In some embodiments, the divider may be a dual modulo divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by N or N+1 (eg, based on carry) to provide a fractional division ratio. In some example embodiments, the DLL may include a cascaded set of tunable delay elements, phase detectors, charge pumps, and D flip-flops. In these embodiments, the delay elements may be configured to decompose the VCO cycle into Nd equal phase groupings, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

In some embodiments, the synthesizer circuit 706D may be configured to generate the carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (eg, twice the carrier frequency, four times the carrier frequency ) and used in conjunction with a quadrature generator and divider circuit to generate multiple signals at the carrier frequency with multiple different phases relative to each other. In some embodiments, the output frequency may be the LO frequency (fLO). In some embodiments, RF circuitry 706 may include an IQ/polar converter.

FEM circuit 708 may include a receive signal path, which may include a path configured to operate on RF signals received from one or more antennas 710, amplify the received signals and provide an amplified version of the received signals to RF circuit 706 for use circuit for further processing. FEM circuit 708 may also include a transmit signal path, which may include circuitry configured to amplify signals provided by RF circuit 706 for transmission for transmission by one or more of one or more antennas 710 . In various embodiments, the amplification through the transmit signal path or the receive signal path may be done only in RF circuit 706 , only in FEM 708 , or in both RF circuit 706 and FEM 708 .

In some embodiments, the FEM circuit 708 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuit may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuit may include an LNA for amplifying the received RF signal and providing the amplified receive RF signal as an output (eg, to RF circuit 706). The transmit signal path of FEM circuit 708 may include: a power amplifier (PA) for amplifying the input RF signal (eg, provided by RF circuit 706 ); and one or more filters for generating the RF signal for use in Subsequent transmissions (eg, by one or more of the one or more antennas 710).

In some embodiments, PMC 712 may manage the power provided to baseband circuitry 704 . In particular, PMC 712 may control power selection, voltage scaling, battery charging, or DC-DC conversion. The PMC 712 may typically be included when the device 700 can be powered by a battery, such as when the device is included in a UE. PMC 712 can improve power conversion efficiency while providing desired implementation size and thermal dissipation characteristics.

Although FIG. 7 shows PMC 712 coupled only to baseband circuitry 704, in other embodiments, PMC 712 may additionally or alternatively be coupled to other components and perform similar power management operations for the other components, such as but not limited to Application circuit 702 , RF circuit 706 or FEM 708 .

In some embodiments, PMC 712 may control, or be part of, various power saving mechanisms of device 700 . For example, if the device 700 is in the RRC_Connected state (where it is still connected to the RAN node because it expects to receive traffic shortly), it may enter a state called discontinuous reception mode (DRX) after a period of inactivity. During this state, the device 700 may be powered down for brief intervals, thereby conserving power.

If there is no data traffic activity for an extended period of time, the device 700 may transition to the RRC_Idle state (where it is disconnected from the network and does not perform operations such as channel quality feedback, handover, etc.). The device 700 enters a very low power state, and it performs paging, where it periodically wakes up again to listen to the network, and then powers down again. Device 700 cannot receive data in this state, in order to receive data it must transition back to the RRC_Connected state.

Additional power saving modes may allow the device to be unavailable to the network for periods longer than the paging interval (ranging from seconds to hours). During this time, the device is completely unreachable from the network and can be powered down completely. Any data sent during this time incurs a large delay and is assumed to be acceptable.

The processor of the application circuit 702 and the processor of the baseband circuit 704 may be used to execute elements of one or more instances of the protocol stack. For example, the processors of the baseband circuitry 704 (alone or in combination) may be used to perform Layer 3, Layer 2, or Layer 1 functions, while the processors of the application circuitry 704 may utilize data (eg, packetized data) received from these layers. , and further perform Layer 4 functions (eg, Transport Communication Protocol (TCP) and User Datagram Protocol (UDP) layers). As mentioned herein, layer 3 may include a radio resource control (RRC) layer, which will be described in further detail below. As mentioned herein, Layer 2 may include a Medium Access Control (MAC) layer, a Radio Link Control (RLC) layer, and a Packet Data Convergence Protocol (PDCP) layer, which will be described in further detail below. As mentioned herein, layer 1 may include the physical (PHY) layer of the UE/RAN node, which will be described in further detail below.

Figure 8 shows an example interface for a baseband circuit in accordance with some embodiments. As discussed above, the baseband circuit 704 of FIG. 7 may include processors 704A-704E and memory 704G used by the processors. Each of the processors 704A-704E may respectively include a memory interface to send/receive data to/from the memory 704G.

组件(例如，低功耗

)、

组件和其他通信组件发送/接收数据的接口)和电源管理接口820(例如，用于向/从PMC 712发送/接收功率或控制信号的接口)。Baseband circuitry 704 may also include one or more interfaces for communicatively coupling to other circuits/devices, such as memory interface 812 (eg, an interface for sending/receiving data to/from memory external to baseband circuitry 704), Application circuit interface 814 (eg, an interface for sending/receiving data to/from the application circuit 702 of FIG. 7 ), RF circuit interface 816 (eg, an interface for sending/receiving data to/from the RF circuit 706 of FIG. 7 ) ), wireless hardware connection interface 819 (for example, to/from Near Field Communication (NFC) components,

components (e.g., low power

),

components and other communication components to send/receive data) and a power management interface 820 (eg, an interface for sending/receiving power or control signals to/from the PMC 712).

9 is a diagram illustrating the ability to read instructions from a machine-readable or computer-readable medium (eg, a non-transitory machine-readable storage medium) and perform any one or more of the methods discussed herein, according to some example embodiments Block diagram of components. Specifically, FIG. 9 shows a graphical representation of hardware resources 900, including one or more processors (or processor cores) 910, one or more memory/storage devices 920, and one or more communication resources 930, among which Each may be communicatively coupled via bus 940 . For embodiments utilizing node virtualization (eg, NFV), hypervisor 902 may be executed to provide an execution environment for one or more network slices/sub-slices to utilize hardware resources 900 .

Processor 910 (eg, central processing unit (CPU), reduced instruction set computing (RISC) processor, complex instruction set computing (CISC) processor, graphics processing unit (GPU), digital signal processor (DSP), eg, baseband A processor, an application specific integrated circuit (ASIC), a radio frequency integrated circuit (RFIC), another processor, or any suitable combination thereof) may include, for example, processor 912 and processor 914 .

Memory/storage 920 may include main memory, disk storage, or any suitable combination thereof. Memory/storage 920 may include, but is not limited to, any type of volatile or non-volatile memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), erasable programmable read only memory (EPROM), Electrically Erasable Programmable Read Only Memory (EEPROM), Flash Memory, Solid State Storage, etc.

组件(例如，低功耗

)、

组件和其他通信组件。Communication resources 930 may include interconnect or network interface components or other suitable devices to communicate with one or more peripheral devices 904 or one or more databases 906 via network 908 . For example, communication resources 930 may include wired communication components (eg, for coupling via Universal Serial Bus (USB)), cellular communication components, NFC components,

components (e.g., low power

),

components and other communication components.

Instructions 950 may include software, programs, applications, applets, apps, or other executable code for causing at least any processor 910 to perform any one or more of the methods discussed herein. Instructions 950 may reside fully or partially within at least one of processor 910 (eg, within the processor's cache), memory/storage device 920, or any suitable combination thereof. Furthermore, any portion of instructions 950 may be transmitted to hardware resource 900 from any combination of peripheral device 904 or database 906 . Accordingly, the memory of the processor 910, the memory/storage devices 920, the peripheral devices 904, and the database 906 are examples of computer-readable and machine-readable media.

A number of examples related to embodiments of the above-described techniques will be given next.

In a first example, the apparatus of a radio access network (RAN) node may include: an interface to a radio frequency (RF) circuit; and one or more processors for inserting a serial number (SN) into a plurality of user data in each user data packet of the packet, the plurality of user data packets are directed to a user equipment (UE) connected to the RAN node, the SN is based on the relative sequential position of each user data packet of the plurality of user data packets; And before causing at least one user data packet of the plurality of user data packets to be transmitted to the UE via the RF circuit, as part of a handover procedure, it is determined that the UE is to be transferred to a target RAN node, and all The at least one user data packet is transferred to the target RAN node during the handover procedure together with an indication of how the at least one data packet would have been transmitted by the RAN node to the UE prior to the handover procedure.

In Example 2, the subject matter of Example 1 or any examples herein, wherein the SN of each user data packet is further based on an SN allocated by the RAN node for transmitting the plurality of user data packets to the UE Data Radio Bearer (DRB).

In Example 3, the subject matter of Example 2 or any example herein, wherein the indication includes an identifier of the DRB.

In Example 4, the subject matter of Example 1 or any examples herein, wherein the SN of each user data packet is further based on a quality of service (QoS) associated with transmitting the plurality of user data packets to the UE.

In Example 5, the subject matter of Example 4 or any examples herein, wherein the indication includes an identifier of a QoS level associated with transmitting the plurality of user data packets to the UE.

In Example 6, the subject matter of Example 1 or any examples herein, wherein the one or more processors cause the at least one user data packet to be sent to the UE based on the RAN node not already causing the at least one user data packet to be sent to the UE. A user data packet is transferred to the target RAN node.

In Example 7, the subject matter of Example 1 or any of the examples herein, wherein the one or more processors cause the RAN node to have not received an acknowledgment message from the UE for the at least one user data packet based on the The at least one user data packet is transferred to the target RAN node.

In Example 8, the subject matter of Example 1 or any examples herein, wherein the one or more processors are based on the RAN node having not received from the UE a user data packet prior to the at least one user data packet an acknowledgment message, causing the at least one user data packet to be transferred to the target RAN node.

In Example 9, the apparatus of a radio access network (RAN) node may include: an interface to a radio frequency (RF) circuit; and one or more processors for receiving a plurality of user data packets from a source RAN node of a handover procedure , the multiple user data packets are directed to a user equipment (UE) corresponding to the handover process, and each user data packet of the multiple user data packets includes each user data packet based on the multiple user data packets a sequence number (SN) of a relative sequential position of the packet; determining a data radio bearer (DRB) used to transmit the plurality of user data packets to the UE; as part of the handover procedure via the RF circuit An interface receives an indication that the UE is ready to communicate with the RAN node; and causes the plurality of user data packets to be transmitted to the UE via the interface of the RF circuit using the DRB.

In Example 10, the subject matter of Example 9 or any examples herein, wherein the SN of each user data packet is further based on a SN assigned by the source RAN node for transmitting the plurality of user data packets to the UE Data Radio Bearer (DRB).

In Example 11, the subject matter of Example 10 or any examples herein, wherein each user data packet of the plurality of user data packets includes an identifier associated with a DRB allocated by the source RAN node.

In Example 12, the subject matter of Example 11 or any of the examples herein, wherein the one or more processors determine the DRB based on the identifier such that the one or more processors use the data generated by the source The DRB allocated by the RAN node causes the plurality of user data packets to be transmitted to the UE.

In Example 13, the subject matter of Example 11 or any examples herein, wherein: the DRB used to transmit the plurality of user data packets to the UE is different from the DRB allocated by the source RAN node, and the one or more processors are further configured to: map the SN to another sequence number (SN) based on the DRB used to transmit the plurality of user data packets; and map the other sequence A number (SN) is inserted into each user data packet of the plurality of user data packets.

In Example 14, the subject matter of Example 9 or any examples herein, wherein the SN of each user data packet is based on a quality of service (QoS) associated with the source RAN node transmitting the plurality of user data packets to the UE .

In Example 15, the subject matter of Example 14 or any examples herein, wherein the one or more processors are further configured to: determine a service utilized by a RAN node to transmit the plurality of user data packets to the UE quality (QoS); and mapping an identifier associated with the QoS included in the plurality of user data packets to a QoS with which the RAN node is to transmit the plurality of user data packets to the UE.

In Example 16, the subject matter of Example 9 or any examples herein, wherein the one or more processors are further configured to: determine that the UE has received the plurality of user data packets; The UE communicates with another DRB that is different from the DRB; and causing the other DRB to be used in place of the DRB for communicating with the UE.

In Example 17, the subject matter of Example 9 or any of the examples herein, wherein before causing the plurality of user data packets to be transmitted to the UE, the one or more processors are further configured to: determine the further a DRB; causing configuration information for handover to the other DRB to be sent to the UE; and using the other DRB to communicate with the UE after transmitting the plurality of user data packets to the UE communication.

In Example 18, the subject matter of Example 9 or any examples herein, wherein the one or more processors further receive an acknowledgement from the UE for at least one user data packet of the plurality of user data packets, and excludes The at least one user data packet is sent to the UE.

In Example 19, the subject matter of Example 9 or any examples herein, wherein the one or more processors further receive an end marker packet indicating that the UE has received the plurality of user data packets.

In Example 20, the subject matter of Examples 1 or 9 or any of the examples herein, wherein the RAN node comprises a New Radio (NR) base station.

In Example 21, the subject matter of Examples 1 or 9 or any examples herein, wherein the plurality of user data packets are transmitted via a user plane of the wireless telecommunications network.

In Example 22, the apparatus of a user equipment (UE) may include: an interface to a radio frequency (RF) circuit; and one or more processors for: from a first radio access network (RAN) via the interface of the RF circuit ) node receives a plurality of first user data packets, each user data packet of the plurality of first user data packets including a sequence number ( SN); receive via the interface of the RF circuit an instruction to participate in a handover procedure involving the first RAN node and the second RAN node; as part of the handover procedure from the second RAN node via the interface of the RF circuit receiving a plurality of second user data packets, each user data packet of the plurality of second user data packets comprising relative to the plurality of first user data packets and the plurality of second user data packets on a per user data packet basis an SN of a sequential position of the data packet; and based on the SN of each user data packet of the plurality of first user data packets and the plurality of second user data packets, associating the plurality of first user data packets with the all user data packets The plurality of second user data packets are combined.

In Example 23, the subject matter of Example 22 or any examples herein, wherein the one or more processors are further configured to: based on the instructions, cause a message to be transmitted to the first via the interface of the RF circuit A second RAN node indicating that the UE is configured to communicate with the second RAN node.

In Example 24, the subject matter of Example 22 or any examples herein, wherein the one or more processors are further configured to: based on the plurality of first user data packets and the plurality of second user data packets The SN of each user data packet, determining whether a transmission failure occurs; and transmitting a retransmission request of the user data packet corresponding to the transmission failure to the second RAN node.

In Example 25, the subject matter of Example 22 or any examples herein, wherein the one or more processors are further configured to: for at least one user data packet of the plurality of first user data packets, based on the at least one user data packet, deleting the at least one user data packet based on the UE not sending an acknowledgment message to the first RAN node; and receiving another copy of the at least one user data packet as a source from the first RAN node; A portion of a plurality of second user data packets of two RAN nodes.

In Example 26, the subject matter of Example 25 or any examples herein, wherein the one or more processors are further configured to: based on another user data packet of the first plurality of user data packets having the The SN following the SN of at least one user data packet, the other user data packet is deleted.

In Example 27, the subject matter of Example 22 or any of the examples herein, wherein the one or more processors are further configured to: determine that all of the plurality of first user data packets and the plurality of second user data packets have been received user data packets, and cause an end marker packet to be transmitted to the second RAN node, indicating that all of the plurality of first user data packets and the plurality of second user data packets have been received.

In Example 28, a computer-readable medium may contain program instructions for causing one or more processors associated with a radio access network (RAN) node to insert a serial number (SN) into a In each user data packet of a plurality of user data packets directed to a user equipment (UE) connected to a RAN node, the SN is based on the SN of each user data packet of the plurality of user data packets. a relative sequential position; and prior to causing at least one user data packet of the plurality of user data packets to be transmitted to the UE, as part of a handover procedure, determining that the UE is to be transferred to a target RAN node, and causing the UE to At least one user data packet is transferred to the target RAN node during the handover procedure, together with an indication of how the at least one data packet would have been transmitted by the RAN node to the UE prior to the handover procedure.

In Example 29, the subject matter of Example 28 or any examples herein, wherein the SN of each user data packet is further based on data allocated by the RAN node for transmitting the plurality of user data packets to the UE Radio Bearer (DRB).

In Example 30, the subject matter of Example 29 or any example herein, wherein the indication includes an identifier of the DRB.

In Example 31, the subject matter of Example 28 or any examples herein, wherein the SN of each user data packet is further based on a quality of service (QoS) associated with transmitting the plurality of user data packets to the UE.

In Example 32, the subject matter of Example 31 or any examples herein, wherein the indication includes an identifier of a QoS level associated with transmitting the plurality of user data packets to the UE.

In Example 33, the subject matter of Example 28 or any examples herein, wherein the one or more processors cause the at least one user data packet to be sent to the UE based on the RAN node not already causing the at least one user data packet to be sent to the UE. A user data packet is transferred to the target RAN node.

In Example 34, the subject matter of Example 28 or any of the examples herein, wherein the one or more processors cause the RAN node to have not received an acknowledgment message for the at least one user data packet from the UE based on the The at least one user data packet is transferred to the target RAN node.

In Example 35, the subject matter of Example 28 or any examples herein, wherein the one or more processors are based on the RAN node having not received from the UE a user data packet prior to the at least one user data packet an acknowledgment message, causing the at least one user data packet to be transferred to the target RAN node.

In Example 36, a computer-readable medium may contain program instructions for causing one or more processors associated with a radio access network (RAN) node to perform the following operations: receive from a source RAN node of a handover procedure a plurality of user data packets, the plurality of user data packets directed to a user equipment (UE) corresponding to the handover procedure, each user data packet of the plurality of user data packets comprising a plurality of user data packets based on the plurality of user data packets the sequence number (SN) of the relative sequential position of each user data packet of an indication that the UE is ready to communicate with the RAN node; and using the DRB, causing the plurality of user data packets to be transmitted to the UE.

In Example 37, the subject matter of Example 36 or any examples herein, wherein the SN of each user data packet is further based on a SN assigned by the source RAN node for transmitting the plurality of user data packets to the UE Data Radio Bearer (DRB).

In Example 38, the subject matter of Example 37 or any examples herein, wherein each user data packet of the plurality of user data packets includes an identifier associated with a DRB allocated by the source RAN node.

In Example 39, the subject matter of Example 38 or any of the examples herein, wherein the one or more processors determine the DRB based on the identifier such that the one or more processors use the data generated by the source The DRB allocated by the RAN node causes the plurality of user data packets to be transmitted to the UE.

In Example 40, the subject matter of Example 38 or any examples herein, wherein: the DRB used to transmit the plurality of user data packets to the UE is different from the DRB allocated by the source RAN node, and the one or more processors are further configured to: map the SN to another sequence number (SN) based on the DRB used to transmit the plurality of user data packets; and to map the other A sequence number (SN) is inserted into each user data packet of the plurality of user data packets.

In Example 41, the subject matter of Example 36 or any examples herein, wherein the SN of each user data packet is based on a quality of service (QoS) associated with a source RAN node transmitting the plurality of user data packets to the UE .

In Example 42, the subject matter of Example 41 or any examples herein, wherein the one or more processors are further configured to determine a service utilized by a RAN node to transmit the plurality of user data packets to the UE quality (QoS); and mapping an identifier associated with the QoS included in the plurality of user data packets to a QoS with which the RAN node is to transmit the plurality of user data packets to the UE.

In Example 43, the subject matter of Example 36 or any examples herein, wherein the one or more processors are further configured to: determine that the UE has received the plurality of user data packets; The UE communicates with another DRB that is different from the DRB; and causing the other DRB to be used in place of the DRB for communicating with the UE.

In Example 44, the subject matter of Example 36 or any of the examples herein, wherein before causing the plurality of user data packets to be transmitted to the UE, the one or more processors are further configured to: determine the further a DRB; causing configuration information for handover to the other DRB to be sent to the UE; and using the other DRB to communicate with the UE after transmitting the plurality of user data packets to the UE communication.

In Example 45, the subject matter of Example 36 or any examples herein, wherein the one or more processors further receive an acknowledgement from the UE for at least one user data packet of the plurality of user data packets, and excludes The at least one user data packet is sent to the UE.

In Example 46, the subject matter of Example 36 or any examples herein, wherein the one or more processors further receive an end marker packet indicating that the UE has received the plurality of user data packets.

In Example 47, the subject matter of Examples 28 or 36 or any of the examples herein, wherein the RAN node comprises a New Radio (NR) base station.

In Example 48, the subject matter of Examples 28 or 36 or any example herein, wherein the plurality of user data packets are transmitted via a user plane of the wireless telecommunications network.

In Example 49, a computer-readable medium may contain program instructions for causing one or more processors associated with a user equipment (UE) to perform the following operations: from a first radio access network (RAN) node receiving a plurality of first user data packets, each user data packet of the plurality of first user data packets including a sequence number (SN) based on a sequential position of each user data packet of the plurality of first user data packets receiving an instruction to participate in a handover procedure involving the first RAN node and a second RAN node; receiving, as part of the handover procedure, a plurality of second user data packets from the second RAN node, the plurality of first Each user data packet of the two user data packets includes an SN based on the ordinal position of each user data packet relative to the plurality of first user data packets and the plurality of second user data packets; and based on the plurality of user data packets The SN of each of the first user data packets and the plurality of second user data packets, combining the plurality of first user data packets and the plurality of second user data packets.

In Example 50, the subject matter of Example 49 or any of the examples herein, wherein the one or more processors are further configured to: based on the instructions, cause a message to be transmitted to the second RAN node indicating the UE is configured to communicate with the second RAN node.

In Example 51, the subject matter of Example 49 or any examples herein, wherein the one or more processors are further configured to: based on the plurality of first user data packets and the plurality of second user data packets The SN of each user data packet, determining whether a transmission failure occurs; and transmitting a retransmission request of the user data packet corresponding to the transmission failure to the second RAN node.

In Example 52, the subject matter of Example 49 or any examples herein, wherein the one or more processors are further configured to: for at least one user data packet of the plurality of first user data packets, based on the at least one user data packet, deleting the at least one user data packet based on the UE not sending an acknowledgment message to the first RAN node; and receiving another copy of the at least one user data packet as a source from the first RAN node; A portion of a plurality of second user data packets of two RAN nodes.

In Example 53, the subject matter of Example 52 or any of the examples herein, wherein the one or more processors are further configured to: based on another user data packet of the plurality of first user data packets having the The SN following the SN of at least one user data packet, the other user data packet is deleted.

In Example 54, the subject matter of Example 49 or any examples herein, wherein the one or more processors are further configured to: determine that all of the plurality of first user data packets and the plurality of second user data packets have been received user data packets, and cause an end marker packet to be transmitted to the second RAN node, indicating that all of the plurality of first user data packets and the plurality of second user data packets have been received.

In Example 55, the apparatus of a radio access network (RAN) node can include means for inserting a sequence number (SN) into each user data packet of a plurality of user data packets, the plurality of user data packets pointing to a user equipment (UE) connected to a RAN node, the SN is based on the relative sequential position of each user data packet of the plurality of user data packets; in making at least one user data packet of the plurality of user data packets means for determining, as part of a handover procedure, that the UE is to be transferred to a target RAN node prior to transmission to the UE; and for causing the at least one user data packet to precede the handover procedure with at least one data packet Together with an indication of how it would otherwise be transmitted by the RAN node to the UE, the module is transferred to the target RAN node during the handover procedure.

In Example 56, the subject matter of Example 55 or any examples herein, wherein the SN of each user data packet is further based on data allocated by the RAN node for transmitting the plurality of user data packets to the UE Radio Bearer (DRB).

In Example 57, the subject matter of Example 56 or any example herein, wherein the indication includes an identifier of the DRB.

In Example 58, the subject matter of Example 55 or any examples herein, wherein the SN of each user data packet is further based on a quality of service (QoS) associated with transmitting the plurality of user data packets to the UE.

In Example 59, the subject matter of Example 58 or any example herein, wherein the indication includes an identifier of a QoS level associated with transmitting the plurality of user data packets to the UE.

In Example 60, the subject matter of Example 55 or any of the examples herein, further comprising: for causing the at least one user data packet to be sent to the UE based on the RAN node not having caused the at least one user data packet to be sent to the UE A module transferred to the target RAN node.

In Example 61, the subject matter of Example 55 or any of the examples herein, further comprising causing the at least one user The data packets are transferred to the module of the target RAN node.

In Example 62, the subject matter of Example 55 or any of the examples herein, further comprising for causing the RAN node to have not received an acknowledgement message from the UE for a user data packet preceding the at least one user data packet The at least one user data packet is transferred to the module of the target RAN node.

In Example 63, the apparatus for a radio access network (RAN) node can include means for receiving a plurality of user data packets from a source RAN node of a handover procedure, the plurality of user data packets directed to a phase associated with the handover procedure a corresponding user equipment (UE), each user data packet of the plurality of user data packets includes a sequence number (SN) based on a relative sequential position of each user data packet of the plurality of user data packets; for determining means for transmitting the plurality of user data packets to a data radio bearer (DRB) of the UE; means for receiving an indication that the UE is ready to communicate with the RAN node as part of the handover procedure and means for causing the plurality of user data packets to be transmitted to the UE using the DRB.

In Example 64, the subject matter of Example 63 or any examples herein, wherein the SN of each user data packet is further based on a SN assigned by the source RAN node for transmitting the plurality of user data packets to the UE Data Radio Bearer (DRB).

In Example 65, the subject matter of Example 64 or any examples herein, wherein each user data packet of the plurality of user data packets includes an identifier associated with a DRB allocated by the source RAN node.

In Example 66, the subject matter of Example 65 or any of the examples herein, further comprising: for determining the DRB based on the identifier such that the one or more processors use the DRB allocated by the source RAN node means for causing the plurality of user data packets to be transmitted to the UE.

In Example 67, the subject matter of Example 65 or any examples herein, wherein: the DRB used to transmit the plurality of user data packets to the UE is different from the DRB allocated by the source RAN node, and the apparatus Also comprising: means for mapping the SN to another sequence number (SN) based on the DRB used to transmit the plurality of user data packets; and for mapping the another sequence number A number (SN) is inserted into the module of each user data packet of the plurality of user data packets.

In Example 68, the subject matter of Example 63 or any examples herein, wherein the SN of each user data packet is based on a quality of service (QoS) associated with a source RAN node transmitting the plurality of user data packets to the UE .

In Example 69, the subject matter of Example 68 or any of the examples herein, further comprising: means for determining a quality of service (QoS) with which a RAN node is to transmit the plurality of user data packets to the UE; and means for mapping the identifiers associated with the QoS included in the plurality of user data packets to the QoS utilized by the RAN node to transmit the plurality of user data packets to the UE.

In Example 70, the subject matter of Example 63 or any of the examples herein, further comprising: means for determining that the UE has received the plurality of user data packets; means for another DRB that is different from the DRB; and means for causing the another DRB to be used in place of the DRB for communicating with the UE.

In Example 71, the subject matter of Example 63 or any examples herein, further comprising: means for determining the other DRB prior to causing the plurality of user data packets to be transmitted to the UE; for using for configuration information for switching to the other DRB is sent to the UE; and means for communicating with the UE using the another BRD after the plurality of user data packets are transmitted to the UE module.

In Example 72, the subject matter of Example 63 or any examples herein, further comprising: for receiving an acknowledgement from the UE for at least one user data packet of the plurality of user data packets, and excluding the at least one user data packet The packets are sent to the modules of the UE.

In Example 73, the subject matter of Example 63 or any examples herein, further comprising means for receiving an end marker packet indicating that the UE has received the plurality of user data packets.

In Example 74, the subject matter of Examples 55 or 66 or any of the examples herein, wherein the RAN node comprises a New Radio (NR) base station.

In Example 75, the subject matter of Examples 55 or 66 or any examples herein, wherein the plurality of user data packets are transmitted via a user plane of the wireless telecommunications network.

In Example 76, a method performed by a radio access network (RAN) node may include inserting a sequence number (SN) into each user data packet of a plurality of user data packets directed to a connection to a user equipment (UE) of a RAN node, the SN is based on a relative sequential position of each user data packet of the plurality of user data packets; and transmitting at least one user data packet of the plurality of user data packets before the UE, as part of the handover procedure, determine that the UE is to be transferred to a target RAN node and make the at least one user data packet and the at least one data packet how it would have been before the handover procedure The indication transmitted by the RAN node to the UE is transferred to the target RAN node during the handover procedure.

In Example 77, the subject matter of Example 76 or any examples herein, wherein the SN of each user data packet is further based on an SN allocated by the RAN node for transmitting the plurality of user data packets to the UE Data Radio Bearer (DRB).

In Example 78, the subject matter of Example 77 or any example herein, wherein the indication includes an identifier of the DRB.

In Example 79, the subject matter of Example 76 or any examples herein, wherein the SN of each user data packet is further based on a quality of service (QoS) associated with transmitting the plurality of user data packets to the UE.

In Example 80, the subject matter of Example 79 or any examples herein, wherein the indication includes an identifier of a QoS level associated with transmitting the plurality of user data packets to the UE.

In Example 81, the subject matter of Example 76 or any of the examples herein, further comprising causing the at least one user data packet based on the RAN node not having received an acknowledgement message from the UE for the at least one user data packet is transferred to the target RAN node.

In Example 82, the subject matter of Example 76 or any of the examples herein, further comprising: based on the RAN node having not received an acknowledgement message from the UE for a user data packet preceding the at least one user data packet, causing the at least one user data packet At least one user data packet is transferred to the target RAN node.

In Example 83, the subject matter of Example 76 or any of the examples herein, further comprising causing the at least one user data packet to be transferred to the UE based on the RAN node not having caused the at least one user data packet to be sent to the UE the target RAN node.

In the foregoing specification, various embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and further embodiments may be practiced, without departing from the broader scope as set forth in the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

For example, although a series of signals and/or operations have been described with respect to Figures 2-6, the order of the signals/operations may be modified in other implementations. Furthermore, independent signals can be executed in parallel.

It will be apparent that the example aspects described above may be implemented in many different forms of software, firmware and hardware in the embodiments shown in the figures. The actual software code or dedicated control hardware used to implement these aspects should not be construed as limiting. Accordingly, the operation and behavior of the various aspects have been described without reference to the specific software code - it being understood that software and control hardware can be designed to implement the aspects based on the description herein.

Even if specific combinations of features are stated in the claims and/or disclosed in the specification, these combinations are not intended to be limiting. Indeed, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification.

No element, act, or instruction used in the present application should be construed as critical or essential unless explicitly stated otherwise. As used herein, instances of use of the word "and" do not necessarily preclude construction of the phrase "and/or" in that instance. Similarly, use of the word "or" as used herein does not necessarily preclude construction of the phrase "and/or" in that instance. Also, as used herein, the article "a" is intended to include one or more items, and can be used interchangeably with the phrase "one or more." Where there is only one item, the words "a", "single", "only" or similar language are used.

Claims (24)

1. An apparatus of a radio access network, RAN, node, the apparatus comprising:

an interface to a radio frequency RF circuit; and

one or more processors configured to:

inserting a sequence number, SN, into at least one of a plurality of user data packets directed to a user equipment, UE, connected to a RAN node, the SN being based on a relative sequential position of the plurality of user data packets; and is

Prior to causing the at least one of the plurality of user data packets to be transmitted to the UE via the RF circuitry,

determining, as part of a handover procedure, that the UE is to be transferred to a target RAN node,

causing the at least one user data packet to be transferred to the target RAN node during the handover procedure, along with an indication of how the at least one user data packet would have been transmitted to the UE by the RAN node via the interface prior to the handover procedure, wherein the indication comprises an identifier of a data radio bearer, DRB, allocated by the RAN node for transmission of the plurality of user data packets to the UE, and wherein the target RAN node determines whether to use the DRB or another DRB different from the DRB for transmission of the at least one user data packet to the UE.

2. The apparatus of claim 1, wherein the SN of the at least one user data packet is further based on the DRB.

3. The apparatus of claim 1, wherein the SN of the at least one user data packet is further based on a quality of service (QoS) associated with transmitting the plurality of user data packets to the UE.

4. The apparatus of claim 3, wherein the indication comprises an identifier of a QoS class associated with transmitting the plurality of user data packets to the UE.

5. The apparatus of claim 1 or 4, wherein the one or more processors cause the at least one user data packet to be transferred to the target RAN node based on the RAN node not having caused the at least one user data packet to be transmitted to the UE.

6. The apparatus of claim 1 or 4, wherein the one or more processors cause the at least one user data packet to be transferred to the target RAN node based on the RAN node not having received an acknowledgement message from the UE regarding the at least one user data packet.

7. The apparatus of claim 1 or 4, wherein the one or more processors cause the at least one user data packet to be transferred to the target RAN node based on the RAN node not having received an acknowledgement message from the UE regarding a user data packet preceding the at least one user data packet.

8. The apparatus of claim 1, wherein the RAN node comprises a new air interface, NR, base station.

9. The apparatus of claim 1 or 8, wherein the plurality of user data packets are transmitted via a user plane of a wireless telecommunications network.

10. An apparatus of a radio access network, RAN, node, the apparatus comprising:

an interface to a Radio Frequency (RF) circuit; and

one or more processors configured to:

receiving a plurality of user data packets from a source RAN node of a handover procedure, the plurality of user data packets being directed to a user equipment, UE, corresponding to the handover procedure, at least one of the plurality of user data packets comprising a sequence number, SN, based on a relative sequential position of the plurality of user data packets;

receiving, from the source RAN node, an indication of how the at least one of the plurality of user data packets would otherwise be transmitted by the source RAN node to the UE prior to the handover procedure, wherein the indication comprises an identifier of a data radio bearer, DRB, allocated by the RAN node for transmission of the plurality of user data packets to the UE;

determining, based on the indication, whether to use the DRB or another DRB different from the DRB for transmitting the plurality of user data packets to the UE;

receiving, via the interface, an indication that the UE is ready to communicate with the RAN node as part of the handover procedure; and is

Causing the plurality of user data packets to be transmitted to the UE via the interface using the DRB.

11. The apparatus of claim 10, wherein the SN of the at least one user data packet is further based on the DRB.

12. The apparatus of claim 10, wherein:

the one or more processors are further to:

mapping the SN to another Sequence Number (SN) that is based on the DRB used to transmit the plurality of user data packets; and

inserting the further sequence number SN into the at least one of the plurality of user data packets.

13. The apparatus of claim 10, wherein the SN of the at least one user data packet is based on a quality of service, QoS, associated with the source RAN node transmitting the plurality of user data packets to the UE.

14. The apparatus of claim 13, wherein the one or more processors are further configured to:

determining a quality of service, QoS, with which the RAN node is to transmit the plurality of user data packets to the UE; and

mapping an identifier associated with the QoS included in the plurality of user data packets to the QoS with which the RAN node is to transmit the plurality of user data packets to the UE.

15. The apparatus of claim 10 or 14, wherein the one or more processors are further configured to:

determining that the UE has received the plurality of user data packets;

determining another DRB different from the DRB for communication with the UE; and

causing the other DRB to be used in place of the DRB for communication with the UE.

16. The apparatus of claim 10 or 14, wherein prior to causing the plurality of user data packets to be transmitted to the UE, the one or more processors are further to:

determining another DRB;

configuration information for handover to the other DRB is transmitted to the UE; and

communicating with the UE using the other DRB after transmitting the plurality of user data packets to the UE.

17. The apparatus of claim 10 or 14, wherein the one or more processors are further to receive an acknowledgement from the UE regarding at least one user data packet of the plurality of user data packets and exclude the at least one user data packet from being sent to the UE.

18. The apparatus of claim 10 or 14, wherein the one or more processors are further to receive an end-marker packet indicating that the UE has received the plurality of user data packets.

19. The apparatus of claim 10, wherein the RAN node comprises a new air interface, NR, base station.

20. The apparatus of claim 10, wherein the plurality of user data packets are transmitted via a user plane of a wireless telecommunications network.

21. An apparatus of a User Equipment (UE), the apparatus comprising:

an interface to a radio frequency RF circuit; and

one or more processors configured to:

receiving a plurality of first user data packets from a first radio access network, RAN, node via the interface, at least one of the plurality of first user data packets comprising a sequence number, SN, based on an order position of the at least one of the plurality of first user data packets;

receiving, via the interface, an instruction to participate in a handover procedure involving the first RAN node and a second RAN node;

receiving, as part of the handover procedure, a plurality of second user data packets from the second RAN node via the interface, at least one of the plurality of second user data packets comprising a SN based on a sequential position of the at least one user data packet relative to the plurality of first user data packets and the plurality of second user data packets, wherein the second RAN node receives the plurality of second user data packets from the first RAN node and an indication of how the at least one of the plurality of second user data packets would otherwise be transmitted to the UE by the first RAN node prior to the handover procedure, wherein the indication comprises an identifier of a Data Radio Bearer (DRB) allocated by the RAN node for transmission of the plurality of user data packets to the UE, and wherein the second RAN node sends the at least one of the plurality of second user data packets to the UE based on the indication by determining whether to use the DRB or another DRB different from the DRB; and is

Merging the plurality of first user data packets with the plurality of second user data packets based on the SN of the at least one of the plurality of first user data packets and the plurality of second user data packets.

22. The apparatus of claim 21, wherein the one or more processors are further configured to:

based on the instruction, cause a message to be transmitted to the second RAN node via the interface, the message indicating that the UE is configured to communicate with the second RAN node.

23. The apparatus of claim 21, wherein the one or more processors are further configured to:

determining whether a transmission failure occurs based on a SN of the at least one of the plurality of first user data packets and the plurality of second user data packets; and

transmitting a retransmission request for a user data packet corresponding to the transmission failure to the second RAN node.

24. The apparatus of claim 21, wherein the one or more processors are further configured to:

for at least one user data packet of the plurality of first user data packets, deleting the at least one user data packet based on the at least one user data packet in accordance with the UE not sending an acknowledgement message to the first RAN node; and

receiving another copy of the at least one user data packet as part of the plurality of second user data packets from the second RAN node.

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