WO2018119123A1

WO2018119123A1 - Systems and methods for packet forwarding during handover procedures

Info

Publication number: WO2018119123A1
Application number: PCT/US2017/067685
Authority: WO
Inventors: Sudeep Palat; Richard BURDIDGE; Candy YIU; Yujian Zhang; Sangeetha Bangolae; Youn Hyoung Heo; Marta MARTINEZ TARRADELL; Alexander Sirotkin
Original assignee: Intel IP Corp
Current assignee: Intel IP Corp
Priority date: 2016-12-20
Filing date: 2017-12-20
Publication date: 2018-06-28
Anticipated expiration: 2019-06-20
Also published as: CN110089151B; CN110089151A

Abstract

Techniques described herein may enable packet forwarding during a handover (HO) procedure involving 5th Generation (5G) technology. During a HO procedure, a source Radio Access Network (RAN) node may send user data packets, intended for a User Equipment (UE), to a target RAN node. The packets may each be assigned a Sequence Number (SN) based on a Data Radio Bearer (DRB) or a Quality of Service (QoS) used by the source RAN node to send packets to the UE. The target RAN node may use the same DRB to forward the packets to the UE, a different DRB to forward to the packets to the UE, or a different QoS to forward the packets to the UE. The target RAN node may also, or alternatively, create a record of the packets forwarded to the UE to enable retransmission of the packets if/when appropriate.

Description

SYSTEMS AND METHODS FOR PACKET FORWARDING DURING HANDOVER

PROCEDURES

RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional Patent Application No.

62/436,900, which was filed on December 20, 2016, the contents of which are hereby incorporated by reference as though fully set forth herein.

BACKGROUND

Wireless telecommunication networks may include User Equipment (UE) (e.g., smartphones, tablet computers, laptop computers, etc.) Radio Access Network (RAN) nodes (e.g. , base stations), and a core network. A UE may connect to the core network by communicating with RAN node and registering with the core network. Communications between the UE and the RAN node (also referred to herein as an access node) may occur over signal carriers corresponding to a frequency band.

As the UE moves to different coverage areas within the wireless telecommunication network, the UE may participate in one or more handover (HO) procedures. A handover (HO) procedure may include a process whereby a UE is transferred from one access node to another access node (often referred to herein as a source node and target node, respectively). Leading up to the HO procedure, the source node may receive, from the core network, information directed to the UE and temporarily store the information in a buffer memory before communicating 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 buffer memory of the source node. As such, in addition to the HO procedure enabling the UE to connect to the target node, the HO procedure may include the source node providing the buffered data to the target node and the target node sending the data to the UE (after a connection between the target node and UE has been established).

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments described herein will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals may designate like structural elements. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings.

Fig. 1 illustrates an architecture of a system of a network in accordance with some embodiments; Fig. 2 is a sequence flow diagram of an example process for packet forwarding during a handover procedure, where the source and target nodes use the same Data Radio Bearers (DRBs) to communicate with User Equipment (UE);

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

Fig. 4 is a sequence flow diagram of an example process for packet forwarding during a handover procedure, where the source and target nodes use different DRBs;

Figs. 5 and 6 are sequence flow diagrams of an example of a detailed process for packet forwarding during a handover procedure;

Fig. 7 illustrates example components of a device in accordance with some embodiments;

Fig. 8 illustrates example interfaces of baseband circuitry in accordance with some embodiments; and

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

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

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 is not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents.

In a wireless telecommunication network, a handover (HO) procedure may include a process whereby a UE is transferred from one access node to another access node (often referred to as a source node and target node, respectively). When the source node determines to handover the UE, some information intended for the UE may still be stored in the buffer memory of the source node. As such, in addition to the HO procedure enabling the UE to connect to the target node, the HO procedure may include the source node providing the buffered data for the UE to the target node, and the target node sending the data to the UE after a connection between the target node and UE has been established.

In some scenarios, such as with Long-Term Evolution (LTE) Radio Access

Technology (RAT), providing buffered data to a UE may involve using the Packet Data Convergence Protocol (PDCP) to assign Sequence Numbers (SNs) to Packet Data Units (PDUs) intended for the UE. The SNs may enable the UE to determine which PDUs have been received and which PDUs have not, and to take appropriate action (such as requesting that one or more PDUs be retransmitted to the UE). Additionally, each Data Radio Bearer (DRB) used to communicate data to the UE may have its own instance of PDCP such that the SNs assigned to PDUs communicated over a particular DRB may not depend on, or otherwise be related to, the SNs assigned to PDUs communicated over a different DRB. PDUs may be assigned SNs prior to, and/or while, the PDUs are stored in the memory buffer in preparation of communicating the PDUs to the UE.

With respect to a HO procedure, where PDUs stored in the memory buffer of the source node are forwarded to the target node and then to the UE, it may be useful for the PDUs to retain their SN so that the UE may merge the PDUs from the source node with the PDUs from the target node to arrange the PDUs in the proper sequence and/or determine whether all of the PDUs in a given sequence have been successfully received. When the UE determines that one or more PDUs is missing, the UE may request that the PDUs be retransmitted by the target node, and in response, the target node may retransmit all of the PDUs in a given set or only the missing PDUs. When all of the PDUs are retransmitted, the UE may detect (based on SNs) which PDUs are duplicates and delete/disregard the duplicate PDUs. Since the procedure described above enables the UE to arrange the PDUs from the source and target nodes in the proper sequence and request the retransmission of missing packets, the procedure is sometimes characterized as an in-sequence, lossless delivery of data to a UE engaged in a HO procedure.

An aspect of LTE that may enable SNs assigned by the source node to be used by the target node may include an assurance that the source and target nodes are using the same DRBs to send data to the UE. However, in New Radio (NR) technologies (e.g., next

Generation NodeBs (gNB) and eNBs connected to NR core networks), the mapping of data to DRBs may be up to the RAN node (i.e., the eNB, gNB, etc.). Consequently, a source node and a target node may end up using different DRBs to send data to a UE undergoing a HO procedure. In such a scenario, if the target node uses a different DRB than the source node, the target node may assign SNs to the PDUs that do not correspond to the SNs of PDUs previously sent to the UE by the source node. As a result, the UE may be unable to merge the PDUs from the source node with the PDUs from the target node to arrange the PDUs in a proper order and/or determine whether all of the PDUs of a given transmission have been successfully received.

The techniques described herein may be used to enable in-sequence, lossless delivery of data to UEs engaged in HO procedures involving NR technologies (e.g. , gNBs, eNBs connected to NR core networks, etc.). In one example, the source node may indicate which DRB is being used by the source node to communicate PDUs to the UE, and the target node may use the same DRB to forward the PDUs, received from the source node, to the UE. Once the PDUs have been successfully received by the UE, the target node may reconfigure, according to its own preferences, which DRBs are used to send subsequent PDUs to the UE.

In another example, access nodes (e.g., source nodes and target nodes) may assign

SNs to PDUs based on a criteria, attribute, characteristic, etc., other than the DRB used to communicate the PDU. For instance, the SNs assigned to PDUs may be based on the QoS flow corresponding to the PDUs. As such, different two different QoS flows may have different numbering sequences in PDCP even if/when the two QoS flows belong to the same DRB. Since the QoS flows may be maintained during and after a HO procedure, the SNs of PDUs sent to the UE may in-sequence and lossless.

In another example, each PDU may include a SN assigned by the source node and a SN assigned by the target node. For instance, PDUs sent from the source node, to the target node, may include the SNs assigned by the source node and an indication of how (e.g. , one or more conditions under which, etc.) the PDUs were to be sent, by the source node, to the UE. An example of such an indication may include a DRB ID corresponding to the DRB that was to be used by the source node to transmit the PDUs to the UE. In some embodiments, a different type of identifier (e.g. , other than a DRB ID) may be used to map data packets to a DRB. In another example, such an indication may include a Quality of Service (QoS) ID corresponding to a QoS with which the source node was to transmit the PDUs to the UE. In some embodiments, a different type of identifier (e.g., other than a QoS ID) may be used to map data packets to a DRB.

The target node may then assign another SN to the PDUs, such that each PDU includes two SNs, one assigned by the source node and another assigned by the target node. The target node may send the PDUs to the UE, and the UE may use the DRB ID and SNs from the source to merge PDUs previously received from the source node with the PDUs received from the target node. Additionally, when the UE discovers that a particular PDU was not been received, the UE may request the retransmission of 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 are to be sent to the target node for transmission to the UE. In one example, when the source node sends PDUs to the UE, the source node may monitor which PDUs are acknowledged (as successfully received) by the UE. As such, if/when the time comes for a HO procedure involving the UE, the source node may determine the oldest PDU for which an acknowledgment has not been received from the UE and may send, to the target node, all of the PDUs starting from the oldest PDU that remains unacknowledged by the UE. In such a scenario, some of the PDUs sent to the target node may include PDUs that have been acknowledged by the UE but that are not as old as the oldest, unacknowledged PDU. In another example, the source node may only send unacknowledged PDUs to the target node. In some embodiments, some of the PDUs received from the source node may not have been assigned a SN, and the target node may identify such PDUs and process them appropriately (e.g. , according to one of the examples described above). Additionally, the techniques described herein may be applied in conjunction with existing HO procedure techniques, such as those describe above with reference to LTE RAT.

Fig. 1 illustrates an architecture of a system 100 of a network in accordance with some embodiments. The system 100 is shown to include UE 101 and a UE 102. The UEs 101 and 102 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more cellular networks), but may also comprise any mobile or non-mobile computing device, such as Personal Data Assistants (PDAs), pagers, laptop computers, desktop computers, wireless handsets, or any computing device including a wireless communications interface.

In some embodiments, any of the UEs 101 and 102 can comprise an Internet of

Things (IoT) UE, which can comprise a network access layer designed for low-power IoT applications utilizing short-lived UE connections. An IoT UE can utilize technologies such as machine-to-machine (M2M) or machine-type communications (MTC) for exchanging data with an MTC server or device via a public land mobile network (PLMN), Proximity-Based Service (ProSe) or device-to-device (D2D) communication, sensor networks, or IoT networks. The M2M or MTC exchange of data may be a machine-initiated exchange of data. An IoT network describes interconnecting IoT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure), with short-lived connections. The IoT UEs may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate the connections of the IoT network.

The UEs 101 and 102 may be configured to connect, e.g., communicatively couple, with a radio access network (RAN) 110— the RAN 110 may be, for example, an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), a NextGen RAN (NG RAN), or some other type of RAN. The UEs 101 and 102 utilize connections 103 and 104, respectively, each of which comprises a physical communications interface or layer (discussed in further detail below); in this example, the connections 103 and 104 are illustrated as an air interface to enable communicative coupling, and can be consistent with cellular communications protocols, such as a Global System for Mobile Communications (GSM) protocol, a code-division multiple access (CDMA) network protocol, a Push-to-Talk (PTT) protocol, a PTT over Cellular (POC) protocol, a Universal Mobile Telecommunications System (UMTS) protocol, a 3 GPP Long Term Evolution (LTE) protocol, a fifth generation (5G) protocol, a New Radio (NR) protocol, and the like.

In this embodiment, the UEs 101 and 102 may further directly exchange

communication data via a ProSe interface 105. The ProSe interface 105 may alternatively be referred to as a sidelink interface comprising one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Discovery Channel (PSDCH), and a Physical Sidelink

Broadcast Channel (PSBCH).

The UE 102 is shown to be configured to access an access point (AP) 106 via connection 107. The connection 107 can comprise a local wireless connection, such as a connection consistent with any IEEE 802.11 protocol, wherein the AP 106 would comprise a wireless fidelity (Wi-Fi®) router. In this example, the AP 106 is shown to be connected to the Internet without connecting to the core network of the wireless system (described in further detail below).

The RAN 110 can include one or more access nodes that enable the connections 103 and 104. These access nodes (ANs) can be referred to as base stations (BSs), NodeBs, eNBs, next Generation NodeBs (gNB), RAN nodes, and so forth, and can comprise ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell). The RAN 110 may include one or more RAN nodes for providing macrocells, e.g., macro RAN node 111, and one or more RAN nodes for providing femtocells or picocells (e.g., cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells), e.g., low power (LP) RAN node 112.

Any of the RAN nodes 111 and 112 can terminate the air interface protocol and can be the first point of contact for the UEs 101 and 102. In some embodiments, any of the RAN nodes 111 and 112 can fulfill various logical functions for the 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.

In accordance with some embodiments, the UEs 101 and 102 can be configured to communicate using Orthogonal Frequency-Division Multiplexing (OFDM) communication signals with each other or with any of the RAN nodes 111 and 112 over a multicarrier communication channel in accordance various communication techniques, such as, but not limited to, an Orthogonal Frequency-Division Multiple Access (OFDMA) communication technique (e.g., for downlink communications) or a Single Carrier Frequency Division Multiple Access (SC-FDMA) communication technique (e.g., for uplink and ProSe or sidelink communications), although the scope of the embodiments is not limited in this respect. The OFDM signals can comprise a plurality of orthogonal subcarriers.

In some embodiments, a downlink resource grid can be used for downlink transmissions from any of the RAN nodes 111 and 112 to the UEs 101 and 102, while uplink transmissions can utilize similar techniques. The grid can be a time-frequency grid, called a resource grid or time-frequency resource grid, which is the physical resource in the downlink in each slot. Such a time-frequency plane representation is a common practice for OFDM systems, which makes it intuitive for radio resource allocation. Each column and each 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 a radio frame. The smallest time-frequency unit in a resource grid is denoted as a resource element. Each resource grid comprises a number of resource blocks, which describe the mapping of certain physical channels to resource elements. Each resource block comprises a collection of resource elements; in the frequency domain, this may represent the smallest quantity of resources that currently can be allocated. There are several different physical downlink channels that are conveyed using such resource blocks.

The physical downlink shared channel (PDSCH) may carry user data and higher-layer signaling to the UEs 101 and 102. The physical downlink control channel (PDCCH) may carry information about the transport format and resource allocations related to the PDSCH channel, among other things. It may also inform the UEs 101 and 102 about the transport format, resource allocation, and H-ARQ (Hybrid Automatic Repeat Request) information related to the uplink shared channel. Typically, downlink scheduling (assigning control and shared channel resource blocks to the UE 102 within a cell) may be performed at any of the RAN nodes 111 and 112 based on channel quality information fed back from any of the UEs 101 and 102. The downlink resource assignment information may be sent on the PDCCH used for (e.g., assigned to) each of the UEs 101 and 102.

The PDCCH may use control channel elements (CCEs) to convey the control information. Before being mapped to resource elements, the PDCCH complex- valued symbols may first be organized into quadruplets, which may then be permuted using a sub- block interleaver for rate matching. Each PDCCH may be transmitted using one or more of these CCEs, where each CCE may correspond to nine sets of four physical resource elements known as resource element groups (REGs). Four Quadrature Phase Shift Keying (QPSK) symbols may be mapped to each REG. The PDCCH can be transmitted using one or more CCEs, depending on the size of the downlink control information (DCI) and the channel condition. There can be four or more different PDCCH formats defined in LTE with different numbers of CCEs (e.g., aggregation level, L=l, 2, 4, or 8).

Some embodiments may use concepts for resource allocation for control channel information that are an extension of the above-described concepts. For example, some embodiments may utilize an enhanced physical downlink control channel (EPDCCH) that uses PDSCH resources for control information transmission. The EPDCCH may be transmitted using one or more enhanced the control channel elements (ECCEs). Similar to above, each ECCE may correspond to nine sets of four physical resource elements known as an enhanced resource element groups (EREGs). An ECCE may have other numbers of EREGs in some situations.

The RAN 110 is shown to be communicatively coupled to a core network (CN) 120 — via an SI interface 113. In embodiments, the CN 120 may be an evolved packet core (EPC) network, a NextGen Packet Core (NPC) network, or some other type of CN. In this embodiment, the SI interface 113 is split into two parts: the Sl-U interface 114, which carries traffic data between the RAN nodes 111 and 112 and the serving gateway (S-GW) 122, and the SI -mobility management entity (MME) interface 115, which is a signaling interface between the RAN nodes 111 and 112 and MMEs 121.

In this embodiment, the CN 120 comprises the MMEs 121, the S-GW 122, the Packet

Data Network (PDN) Gateway (P-GW) 123, and a home subscriber server (HSS) 124. The MMEs 121 may be similar in function to the control plane of legacy Serving General Packet Radio Service (GPRS) Support Nodes (SGSN). The MMEs 121 may manage mobility aspects in access such as gateway selection and tracking area list management. The HSS 124 may comprise a database for network users, including subscription-related information to support the network entities' handling of communication sessions. The CN 120 may comprise one or several HSSs 124, depending on the number of mobile subscribers, on the capacity of the equipment, on the organization of the network, etc. For example, the HSS 124 can provide support for routing/roaming, authentication, authorization,

naming/addressing resolution, location dependencies, etc.

The S-GW 122 may terminate the SI interface 113 towards the RAN 110, and routes data packets between the RAN 110 and the CN 120. In addition, the S-GW 122 may be a local mobility anchor point for inter-RAN node handovers and also may provide an anchor for inter-3GPP mobility. Other responsibilities may include lawful intercept, charging, and some policy enforcement.

The P-GW 123 may terminate an SGi interface toward a PDN. The P-GW 123 may route data packets between the EPC network 123 and external networks such as a network including the application server 130 (alternatively referred to as application function (AF)) via an Internet Protocol (IP) interface 125. Generally, the application server 130 may be an element offering applications that use IP bearer resources with the core network (e.g., UMTS Packet Services (PS) domain, LTE PS data services, etc.). In this embodiment, the P-GW 123 is shown to be communicatively coupled to an application server 130 via an IP communications interface 125. The application server 130 can also be configured to support one or more communication services (e.g., Voice-over-Internet Protocol (VoIP) sessions, PTT sessions, group communication sessions, social networking services, etc.) for the UEs 101 and 102 via the CN 120.

The P-GW 123 may further be a node for policy enforcement and charging data collection. Policy and Charging Enforcement Function (PCRF) 126 is the policy and charging control element of the CN 120. In a non-roaming scenario, there may be a single PCRF in the Home Public Land Mobile Network (HPLMN) associated with a UE's Internet Protocol Connectivity Access Network (IP-CAN) session. In a roaming scenario with local breakout of traffic, there may be two PCRFs associated with a UE's IP-CAN session: a Home PCRF (H-PCRF) within a HPLMN and a Visited PCRF (V-PCRF) within a Visited Public Land Mobile Network (VPLMN). The PCRF 126 may be communicatively coupled to the application server 130 via the P-GW 123. The application server 130 may signal the PCRF 126 to indicate a new service flow and select the appropriate Quality of Service (QoS) and charging parameters. The PCRF 126 may provision this rule into a Policy and Charging Enforcement Function (PCEF) (not shown) with the appropriate traffic flow template (TFT) and QoS class of identifier (QCI), which commences the QoS and charging as specified by the application server 130.

The quantity of devices and/or networks, illustrated in Fig. 1, is provided for explanatory purposes only. In practice, system 100 may include additional devices and/or networks; fewer devices and/or networks; different devices and/or networks; or differently arranged devices and/or networks than illustrated in Fig. 1. For example, while not shown, environment 100 may include devices that facilitate or enable communication between various components shown in environment 100, such as routers, modems, gateways, switches, hubs, etc. Alternatively, or additionally, one or more of the devices of system 100 may perform one or more functions described as being performed by another one or more of the devices of system 100. Additionally, the devices of system 100 may interconnect with each other and/or 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 in, and/or may be physically attached to, one or more other devices of system 100. Also, while "direct" connections may be shown between certain devices in Fig. 1, some of said devices may, in practice, communicate with each other via one or more additional devices and/or networks.

Fig. 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 111-1-1, and target node 111-2. Source node 111 -1-1 and target node 111-2 may each be an example of macro RAN node 111 or LP RAN node 112 described above with reference to Fig. 1. The example of Fig. 2 is provided as a non-limiting example. In practice, 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 of 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 111-1-1 may communicate packets to one another (line 205). Packets, as described herein, may include PDUs communicated between devices (e.g. , UE 101, source node 111-1-1, target node 111 -2, devices of CN 120, etc.) over a user plane of the wireless telecommunication network. Such packets may be referred herein as user data (UD). UE 101 and source node 111-1 -1 may each implement a protocol, such as PDCP, to assign a 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 a first octet of the packet, and all 8 bits of a second octet of the packet. In such embodiments, 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 packet may be configured in a different way.

Source node 111 -1-1 may receive packets (from CN 120) intended for UE 101 , and may temporarily store the packets in a local buffer memory of source node 111-1-1. Prior to transmitting the packets to UE 101, source node 111-1-1 may assign a SN to each packet. In accordance with PDCP, the SN assigned to each packet may be based on the DRB that source node 111-1-1 may use to transmit the packet to UE 101. The SN for the packets may be assigned in a relative sequential order (e.g. , 1 , 2, 3, etc.) that is consistent with the manner (e.g. , the order) in which the packets are to be transmitted, received, read, and/or processed by UE 101. Upon transmitting packets to UE 101, source node 111 -1-1 may monitor which packets have been transmitted (and when) and whether UE 101 has acknowledged any of the transmitted packets. When UE 101 indicates a failure to receive one or more packets, source node 111-1-1 may retransmit the identified packets, record the time or retransmission, and continue to monitor whether UE 101 acknowledges the retransmitted packets. As buffered packets are acknowledged by UE 101, source node 111 -1-1 may (immediately or periodically) remove the packets from the buffer.

The SNs may be assigned by a PDCP layer of a protocol stack implemented by source node 111-1-1. In such embodiments, the PDCP layer may be operating above a radio link control (RLC) layer of the protocol stack, the RLC layer may be operating above a media access control (MAC) layer of the protocol stack, and the MAC layer may be operating above a physical (PHY) layer of the protocol stack. UE 101 may implement a similar protocol stack (e.g. , PDCP layer, RLC layer, MAC layer, and PHY layer) and may send, process, and receive packets in a similar manner as source node 111-1-1. In some embodiments, source node 111-1-1 may assign SNs to packets prior to and during the handover procedure. In some embodiments, source node 111 -1-1 may begin assigning SNs to packets only after determining that UE 101 is to be handedover to another RAN node 111.

Assume that source node 111-1-1 determines that UE 101 should undergo a handover procedure that involves target node 111-2 (block 210). In response, source node 111-1 -1 may stop transmitting packets of user data to UE 101 and determine which of the buffered packets are to be sent to target node 111 -2. In some embodiments, source node 111-1-1 may determine that the packets to be sent to target node 111 -2 include all of the packets transmitted to UE 101 measured from the oldest packet that is still not acknowledged by UE 101. For example, if source node 111-1 -1 sent packets 1 -lO to UE 101, and UE 101 has acknowledged receiving packets 1 -3 and 6-7 (but not 4, 5, or 8-10) target node may determine that packets 4-10 are to be sent to target node 111-2 since packet 4 is the oldest packet that is still not acknowledged by UE 101. By contrast, in some embodiments, source node 111-1-1 may determine that the packets to be sent to target node 111-2 only include packets that have not yet been acknowledged by UE 101. For example, continuing with the example where source node 111-1-1 sent packets 1-10 to UE 101, and UE 101 has acknowledged receiving packets 1 -3 and 6-7 (but not 4, 5, or 8-10) target node may determine that only packets 4, 5, and 8-10 are to be sent to target node 111-2 since packets 1- 3 and 6-7 are already been acknowledged by UE 101.

Source node 111 -1-1 may communicate the determined packets to target node 111-2 (line 220). As shown, each packet may include a corresponding SN and DRB ID. The DRB ID may indicate the DRB that source node 111-1-1 used to determine the SN and that source node 111-1 was to use to transmit the packet to UE 101. In some embodiments, source node 111-1 may only insert DRB IDs in packets that are to be transferred to UE 101 by target node 111-2-2 (e.g., after source node 111-1 determines to perform the handover procedure). In some embodiments, source node 111 -1 may include the DRB ID in all of the packets directed to UE 101 (e.g. , even packets received before source node 111-1 determines to perform the handover procedure. Target node 111-2-2 may buffer and map each packet to a

corresponding DRB based on the DRB ID associated with each packet (block 225).

Additionally, target node 111-2-2 may allocate, based on the DRB IDs, the same DRBs as source node 111-1 for transmitting the packets to UE 101 (block 230). As such, target node 111-2 may communicate the packets to UE 101 using the same DRBs as source node 111-1 (block 235).

Source node 111 -1 may notify UE 101 about the HO procedure by sending an RRC connection reconfiguration request message to UE 101, which may include configuration information for establishing a connection with target node 111-2 (line 235). 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 communicating an RRC connection reconfiguration complete message to target node 111 -2, examples of which are described below in detail with reference to Figs. 5 and 6. In embodiments where (as described above) source node 111 -1 is configured to determine that the packets to be sent to target node 111 -2 include all of the packets transmitted to UE 101 since the oldest packet that has still not been acknowledged by UE 101, UE 101 may operate similarly by discarding packets based on the oldest packet sent by source node 111-1 that UE 111 has still not received successfully (and therefore has not yet acknowledged) (block 240). For example, if source node 111 -1 sent packets 1 -10 to UE 101, and UE 101 has only received packets 1 -3 and 6-7 (but not 4, 5, or 8-10) UE 101 may discard packets 4-10 since packet 4 is the oldest packet that UE 101 still has not

received/acknowledged. Doing so may free up storage capacity of UE 101 since, in such embodiments, target node 111 -2 may be configured to retransmit the packets starting from the oldest, unacknowledged packet (e.g., packets 4-10). By contrast, in embodiments where source node 111-1 only sends unacknowledged packets (e.g. , packets 4, 5, and 8-10) to target node 111-2 such that target node 111 -2 may only transmit the unacknowledged packets to the UE 101 , UE 101 may process, send, etc., the packets successfully received from source node 111-1 (e.g., packets 1-3 and 6-7) to the upper layers (e.g., the IP layer or another type of

Layer 3 protocol) without waiting for the missing packets (e.g. , packets 4, 5, and 8-10) from target node 111-2 (block 245).

After target node 111-2 has successfully transmitted the packets to UE 101, UE 101, source node 111-1 , and target node 111 -2 may complete the HO procedure. Doing so may include one or more of a variety of operations (such as UE 101 detaching from source node 111-1 and communicating an RRC connection reconfiguration complete message to target node 111-2) (line 250). Detailed examples of such operations are described below with reference to Figs. 5 and 6. Target node 111 -2 may send data packets to UE 101 (line 255). In some embodiments, target node 111-2 may send to UE 101 all the data packets that target node 111-2 received from source node 111-1 (line 220). In some embodiments, before target node 111-2 sends data packets to UE 101, UE 101 may send target node 111-2 an acknowledgement message for one or more of the data packets that target node 111-2 may have received from source node 111-1, and target node 111-2 may only send to UE 101 the data packets for which an acknowledgment has not been received (i.e., the unacknowledged packets).

In some embodiments, UE 101 may notify target node 111-2 when the all of the data packets (e.g. , all the packets with SNs from the source side) have been received. In some embodiments, this notification or indication may be provided by UE 101 via an end marker packet or another type of indicator. Additionally, or alternatively, after UE 101 has successfully received the packets from target node 111-2 (line 255), target node 111-2 may reconfigure DRBs for communicating with UE 101 (block 260). For example, the DRBs setup by source node 111-1 to communicate with UE 101 may not be the optimal or otherwise preferred DRBs for target node 111 -2 to communicate with UE 101. As such, after the packets from source node 111 -1 have been successfully received by UE 101, target node 111-2 may reconfigure (e.g. , reassign, reallocate, etc.) the DRBs that target node 111-2 and UE 101 may use to communicate user data to one another (block 260). In some

embodiments, target node 111 -2 may perform these operations at a earlier time. For example, prior to communicating the data packets to UE 101 (line 255), target node 111-2 may determine a DRB that target node 111-2 is to use after communicating the data packets to UE 101 (e.g. , after the HO procedure is complete), and target node 111 -2 may provide UE 101 with configuration information for using the new DRB after UE 101 has received the data packets (e.g., after the HO procedure is complete.

Fig. 3 is a sequence flow diagram of an example process for packet forwarding, based on a QoS ID, during a handover procedure. As shown, the example of Fig. 3 may include UE 101, source node 111-1 , and target node 111 -2. Source node 111 -1 and target node 111 -2 may each be an example of macro RAN node 111 or 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 of 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 communicate user data packets to one another over a user plane (line 305). UE 101 and source node 111-1 may each implement a protocol to assign a SN to each packet. Instead of the SNs for each packet being based on a DRB used to communicate the packet, the SNs for each packet may be based on a QoS flow associated with the packet. A QoS flow associated with a packet may be determined or identified based on QoS flow filters or QoS indicators or other QoS marking information included in the packet. Such information may also, or alternatively, be conveyed over a radio protocol, either in the user plane or as part of configuration information exchanged between UE 101 and CN 120. Since the SN may be based on a QoS flow associated with the packet (instead of, for example, a DRB), one DRB may be used to communicate user data packets corresponding to multiple, distinct numbering sequences. Assume that source node 111-1 determines that UE 101 is to undergo a HO procedure involving target node 111-2 (block 310). In response, source node 111 -1 may stop transmitting packets of user data to UE 101 and determine which of the buffered packets are to be sent 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 of the packets transmitted to UE 101 since the oldest packet that is still not acknowledged by UE 101. For example, if source node 111-1 sent packets 1-10 to UE 101, and UE 101 has acknowledged receiving packets 1 -3 and 6-7 (but not 4, 5, or 8-10) target node 111 -2 may determine that packets 4-10 are to be sent to target node 111-2 since packet 4 is the oldest packet that is still not acknowledged by UE 101. By contrast, in some embodiments, source node 111-1 may determine that the packets to be sent to target node 111-2 only include packets that have not yet been acknowledged by UE 101. For example, continuing with the example where source node 111-1 sent packets 1- 10 to UE 101, and UE 101 has acknowledged receiving packets 1-3 and 6-7 (but not 4, 5, or 8-10) target node 111-2 may determine that only packets 4, 5, and 8-10 are to be sent to target node 111-2 since packets 1 -3 and 6-7 are already been acknowledged by UE 101.

Source node 111 -1 may notify UE 101 about the HO procedure by sending an RRC connection reconfiguration request message to UE 101, which may include configuration information for establishing a connection with target node 111-2 (line 320). The

configuration information may include instructions about which packet forwarding technique is being implemented by the source and target nodes 111 (e.g. , whether target node 111-2 is only to forward unacknowledged packets, etc.). The packet forwarding technique may inform UE 101 which packets to expect 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 communicating an RRC connection reconfiguration complete message to target node 111-2, examples of which are described below in detail with reference to Figs. 5 and 6.

In embodiments where (as described above) source node 111 -1 is configured to determine that the packets to be sent to target node 111 -2 include all of the packets transmitted to UE 101 since the oldest packet that has still not been acknowledged by UE 101, UE 101 may operate similarly by discarding packets based on the oldest packet sent by source node 111-1 that UE 111 has still not received successfully (and therefore has not yet acknowledged) (block 325). For example, if source node 111 -1 sent packets 1 -10 to UE 101, and UE 101 has only received packets 1 -3 and 6-7 (but not 4, 5, or 8-10) UE 101 may discard packets 4-10 since packet 4 is the oldest packet that UE 101 still has not received/acknowledged. Doing so may free up storage capacity of UE 101 since, in such embodiments, target node 111 -2 may be configured to retransmit the packets starting from the oldest, unacknowledged packet (e.g., packets 4-10). By contrast, in embodiments where source node 111-1 only sends unacknowledged packets (e.g. , packets 4, 5, and 8-10) to target node 111-2 such that target node 111 -2 may only transmit the unacknowledged packets to the UE 101 , UE 101 may process, send, etc., the packets successfully received from source node 111-1 (e.g., packets 1-3 and 6-7) to the upper layers (e.g., the IP layer or another type of Layer 3 protocol) without waiting for the missing packets (e.g. , packets 4, 5, and 8-10) from target node 111-2 (block 330).

Source node 111 -1 may communicate the user data packets to target node 111-2 (line

335). As shown, each packet may include a corresponding SN and QoS flow ID. Target node 111-2 may buffer and map each packet to a corresponding QoS flow ID based on the QoS flow ID associated with already each packet (block 340). Additionally, target node 111 - 2 may determine and allocate preferred DRBs for sending the data user packets to UE 101 (block 345). By contrast to the example of Fig. 2, target node 111 -2 may select a different set of DRBs than source node 111-1 for communicating the user data packets to UE 101.

UE 101 , source node 111-1, and target node 111 -2 may complete the HO procedure. Doing so may include one or more of a variety of operations (such as UE 101 detaching from source node 111-1 and communicating an RRC connection reconfiguration complete message to target node 111-2) (line 350). Detailed examples of such operations are described below with reference to Figs. 5 and 6. Target node 111-2 may transmit the user data packets to UE 101 (at line 355). In the event that UE 101 fails to successfully receive one or more of the transmitted packets, UE 101 may send a retransmission request to target node 110 regarding the failed packets, and target node 111 -2 may respond by retransmitting the failed packets (line 360).

Fig. 4 is a sequence flow diagram of an example process for packet forwarding during a handover procedure where 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, which may each be an example of macro RAN node 111 or LP RAN node 112 described above with reference to Fig. 1. The example of Fig. 4 is provided as a non-limiting example. In practice, 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 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 communicate packets to one another (line 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. Prior to transmitting the packets to UE 101, source node 111 -1 may assign a SN to each packet. In accordance with PDCP, the SN assigned to each packet may be based on the DRB that source node 111-1 may use to transmit the packet to UE 101. The SN for the packets may be assigned in a sequential order that is consistent with the manner in which the packets are intended to be received, read, and/or otherwise processed by UE 101. Upon transmitting packets to UE 101, source node 111-1 may monitor which packets have been transmitted (and when) and whether UE 101 has acknowledged any of the transmitted packets. When UE 101 indicates a failure to receive one or more packets, source node 111 -1 may retransmit the identified packets, record the time or retransmission, and continue to monitor whether UE 101 acknowledges the retransmitted packets. As buffered packets are acknowledged by UE 101, source node 111-1 may (immediately or periodically) remove the packets from the buffer.

Assume that source node 111-1 determines that UE 101 should undergo a handover procedure that involves target node 111-2 (block 410). In response, source node 111-1 may stop transmitting packets of user data to UE 101 and determine which of the buffered packets are to be sent 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 of the packets transmitted to UE 101 measured from the oldest packet that is still not acknowledged by UE 101. For example, if source node 111-1 sent packets 1 -10 to UE 101, and UE 101 has acknowledged receiving packets 1 -3 and 6-7 (but not 4, 5, or 8-10) target node may determine that packets 4-10 are to be sent to target node 111-2 since packet 4 is the oldest packet that is still not acknowledged by UE 101. By contrast, in some embodiments, source node 111-1 may determine that the packets to be sent to target node 111-2 only include packets that have not yet been acknowledged by UE 101. For example, continuing with the example where source node 111-1 sent packets 1-10 to UE 101, and UE 101 has acknowledged receiving packets 1 -3 and 6-7 (but not 4, 5, or 8-10) target node may determine that only packets 4, 5, and 8-10 are to be sent to target node 111-2 since packets 1 -3 and 6-7 are already been acknowledged by UE 101. Source node 111 -1 may communicate the determined packets to target node 111 -2 (line 420). As shown, each packet may include a corresponding SN and DRB ID. The DRB ID may indicate the DRB that source node 111-1 used to determine the SN and that source node 111-1 was to use to transmit the packet to UE 101. Source node 111-1 may notify UE 101 about the HO procedure by sending an RRC connection reconfiguration request message to UE 101, which may include configuration information for establishing a connection with target node 111-2 (line 425).

In some embodiments, where source node 111-1 is configured to determine that the packets to be sent to target node 111-2 include all of the packets transmitted to UE 101 since the oldest packet that has still not been acknowledged by UE 101 , UE 101 may operate similarly by discarding packets based on the oldest packet sent by source node 111-1 that UE 111 has still not received successfully (and therefore has not yet acknowledged) (block 430). For example, if source node 111-1 sent packets 1-10 to UE 101, and UE 101 has only received packets 1 -3 and 6-7 (but not 4, 5, or 8-10) UE 101 may discard packets 4-10 since packet 4 is the oldest packet that UE 101 still has not received/acknowl edged. By contrast, in embodiments where source node 111-1 only sends unacknowledged packets (e.g. , packets 4, 5, and 8-10) to target node 111-2 such that target node 111-2 may only transmit the unacknowledged packets to the UE 101, UE 101 may process, send, etc., the packets successfully received from source node 111-1 (e.g., packets 1-3 and 6-7) to the upper layers (e.g. , the IP layer or another type of Layer 3 protocol) without waiting for the missing packets (e.g. , packets 4, 5, and 8-10) from target node 111 -2 (block 435).

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

Additionally, target node 111-2 may determine new SNs for the packets based on the newly determined DRBs, and assign the new SNs to each packet (block 445). In some embodiments, for each packet, target node 111-2 may map (e.g., create a record of) the SNs (and/or DRBs) of source node 111 -1 with the new SNs (and/or DRBs) from target node 111- 2. Doing so may enable target node 111-2 to ensure that the packets are successfully transmitted to UE 101, which may involve acknowledgement messages from UE 101, retransmissions from target node 111-2. UE 101 may communicate an RRC connection reconfiguration complete message to target node 111-2 as part of the HO procedure (line 450), and target node 111-2 may communicate the packets to UE 101 using the same DRBs as source node 111-1 (block 455). In the event that UE 101 fails to successfully receive one or more of the transmitted packets, UE 101 may send a retransmission request to target node 110 regarding the failed packets, and target node 111-2 may respond by retransmitting the failed packets (line 460).

Figs. 5 and 6 are sequence flow diagrams of an example of a detailed process for packet forwarding during a handover procedure. As shown, the example of Fig. 4 may include UE 101, source node 111-1, target node 111-2, SGW 112, and user plane function device(s) 510.

Source node 111 -1 and target node 111-2 may each be an example of macro RAN node 111 or LP RAN node 112 described above with reference to Fig. 1. Similarly, SGW 122 may each an example of S-GW 122 of Fig. 1. User plane function device(s) 510 may include one or more server devices that implements a user plane function (as opposed to, for example, a control plane function) of a 5G (or Next Generation (NG)) CN. Depending on the embodiment, SGW 122 and user plane function device(s) 510 may correspond to the same CN or to different CNs. For example, SGW 122 may correspond to a EPC that supports source node 111-1 , while user plane function device(s) 510 may correspond to a 5G CN that supports target node 111-2.

The example of Figs. 5 and 6 are provided as a non- limiting example. In practice, the example 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 of 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 Fig. 5, UE 101 may send and receive information from CN 120 via a connection with source node 111-1 (line 505). The information may be communicated over a 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. Prior to transmitting the packets to UE 101, source node 111 -1 may assign a SN to each packet. In accordance with PDCP, the SN assigned to each packet may be based on the DRB that source node 111 -1 may use to transmit the packet to UE 101. The SN for the packets may be assigned in a sequential order that is consistent with the manner in which the packets are intended to be received, read, and/or otherwise processed by UE 101. Upon transmitting packets to UE 101, source node 111-1 may monitor which packets have been transmitted (and when) and whether UE 101 has acknowledged any of the transmitted packets. When UE 101 indicates a failure to receive one or more packets, source node 111 -1 may retransmit the identified packets, record the time or retransmission, and continue to monitor whether UE 101 acknowledges the retransmitted packets. As buffered packets are acknowledged by UE 101, source node 111 -1 may (immediately or periodically) remove the packets from the buffer.

Assume that source node 111-1 determines that UE 101 should undergo a handover procedure that involves target node 111-2 (block 510). In response, source node 111-1 may stop transmitting packets of user data to UE 101 and determine which of the buffered packets are to be sent 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 of the packets transmitted to UE 101 measured from the oldest packet that is still not acknowledged by UE 101. For example, if source node 111-1 sent packets 1 -10 to UE 101, and UE 101 has acknowledged receiving packets 1 -3 and 6-7 (but not 4, 5, or 8-10) target node may determine that packets 4-10 are to be sent to target node 111-2 since packet 4 is the oldest packet that is still not acknowledged by UE 101. By contrast, in some embodiments, source node 111-1 may determine that the packets to be sent to target node 111-2 only include packets that have not yet been acknowledged by UE 101. For example, continuing with the example where source node 111-1 sent packets 1-10 to UE 101, and UE 101 has acknowledged receiving packets 1 -3 and 6-7 (but not 4, 5, or 8-10) target node may determine that only packets 4, 5, and 8-10 are to be sent to target node 111-2 since packets 1 -3 and 6-7 are already been acknowledged by UE 101.

Source node 111 -1 may send a layer 3 (L3) HO request to target node 111-2 (line 515). The request may include DRB mapping information that may include an indication of UE 101 and the DRB(s) used by source node 111 -1 to communicate with UE 101. In response, target node 111-2 may perform an admission control operation, which may include a determination of whether to accept or reject the HO request (block 520). This

determination may be based on a variety of factors, such as an availability of wireless resources to communicate with UEs 101, a level of congestion associated with target node 111-2, etc. Assume that target node 111-2 determines to accept the HO request. As shown, target node 111-2 may respond to source node 111-1 by communicating a L3 HO request acknowledgement message (line 525), and source node 111-1 may, in response, send an L3 RRC connection reconfiguration message to UE 101 (line 530). The L3 RRC connection reconfiguration message may include mobility control information, which may include instructions for UE 101 to communicate with target node 111-2.

In response to the L3 RRC connection reconfiguration message, UE 101 may detach from source node 111 -1 and synchronize to target node 111-2 (block 535). In some embodiments, where source node 111-1 is configured to determine that the packets to be sent to target node 111-2 include all of the packets transmitted to UE 101 since the oldest packet that has still not been acknowledged by UE 101 , UE 101 may operate similarly by discarding packets based on the oldest packet sent by source node 111-1 that UE 111 has still not received successfully (and therefore has not yet acknowledged) (block 540). For example, if source node 111-1 sent packets 1-10 to UE 101, and UE 101 has only received packets 1 -3 and 6-7 (but not 4, 5, or 8-10) UE 101 may discard packets 4-10 since packet 4 is the oldest packet that UE 101 still has not received/acknowledged. By contrast, in embodiments where source node 111-1 only sends unacknowledged packets (e.g. , packets 4, 5, and 8-10) to target node 111-2 such that target node 111 -2 may only transmit the unacknowledged packets to the UE 101 , UE 101 may process, send, etc., the packets successfully received from source node 111-1 (e.g., packets 1-3 and 6-7) to the upper layers (e.g., the IP layer or another type of Layer 3 protocol) without waiting for the missing packets (e.g. , packets 4, 5, and 8-10) from target node 111-2 (block 545).

Source node 111 -1 may send a L3 SN status transfer information to target node 111 -2 (line 550) which may include communication standards information for performing the handover procedure. Source node 111-1 may send, to target node 111 -2, UD packet data for forwarding purposes (line 555). As described above, this may include all of the buffered packets transmitted to UE 101 since the oldest packet that has still not been acknowledged by UE 101 (e.g. , packets 1 -3 and 6-7 but not 4, 5, or 8-10). Alternatively, this may only include packets that are buffered by source node 111-1 and unacknowledged by UE 101. (e.g., packets 4, 5, and 8-10 but not 1-3, 6, and 7). Upon receiving the packets form source node 111-1, target node 111-2 may buffer the packets (e.g., for processing and/or subsequent transmission to UE 101).

Depending on the implementation, 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 allocate the packets to the same DRB(s) used by source node 111-1 to transmit packets to UE 101 (see, e.g. , Fig. 2). Alternatively, target node may map the received packets to a QoS used by source node 111-1 to transmit packets to UE 101, and then allocate the received packets to DRB(s) preferred by target node 111 -2 (which may be the same or different DRBs than the DRBs used by source node 111-1 to transmit packets to UE 101) (see, e.g. , Fig. 3). Yet another alternative, target node 111 -2 may determine and allocate preferred DRB(s) for forwarding the packets to UE 101 (which may be the same or different DRBs than the DRBs used by source node 111-1 to transmit packets to UE 101), assign (e.g. , insert into) new SNs to the packets based on the determined DRB(s) , and for each of the received packets, create a record that maps the SNs assigned by source node 111- 1 to the new SNs assigned by target node 111-2 (see, e.g., Fig. 4).

Referring now to Fig. 6, based on the RRC Connection Reconfiguration message from source node 111-1 , UE 101 may reconfigure itself for the handover procedure and send a L3 RRC Connection Reconfiguration Complete message to target node 111-2 (line 605). In response, target node 111-2 and UE 101 may communicate user data packets to one another (line 610). For example, target node 111 -2 may forward, to UE 101 in the downlink (DL) direction), the packets received from source node 111 -1. Additionally, or alternatively, UE 101 may send packets to target node 111 -2 in the uplink (UL) direction. Target node 111 -2 may process and/or forward packets, received from UE 101, to a SGW 122 of target node 111-2 (line 615).

Target node 111-2 may also send an L3 path switch request message to user plane function device(s) 510 (line 620) and user plane function device(s) 510 may respond by sending a L3 modify bearer request message to SGW 122 (line 625). These messages may be to enable/cause devices of CN 120 to switch, in accordance with the handover procedure, the DL path used to communicate packets to UE 101 via target node 111-2. Additionally, in response to the L3 modify bearer response message, SGW 112 may switch DL path information (e.g. , information indicating the DL path from CN 120 to UE 101) based on the handover procedure (e.g., to include target node 111-2) and may send a UD end marker packet to source node 111 -1 (block and line 630). The end marker packet may include an indication of the last packet provided by CN 120 to source node 111-1 for UE 101.

Source node 111 -1 may forward the UD end marker packet to target node 111-2 (line 635), and target node 111-2 and SGW 122 may communicate packets to each other (line 640). The UD end marker packet may inform target node 111-2 about the last packet provided by CN 120 to source node 111 -1 for UE 101. As such, target node 111-2 may use the end marker packet to determine whether the packets from source node 111-1 include the last packet sent from CN 120 to source node 111-1, and/or whether subsequent packets that target node 111-2 receives from CN 120 for UE 101 begin from the end marker packet (e.g., whether packets provided in the DL direction from CN 120 where lost during the handover procedure). If/when target node 111-2 determines that packets from the CN 120 have been lost, target node 111-2 may request retransmission of the lost packets.

SGW 122 may communicate an L3 modify bearer response message to user plane function device(s) 510 (line 645) which may correspond to the previous L3 modify bearer request message (see, line 625). In response, user plane function device(s) 510 may communicate an L3 path switch request acknowledgement message to target node 111-2 (line 650) which may correspond to the previous L3 switch request message (see, line 620). In turn, target node 111-2 may communicate a L3 UE context release message to source node 111-1 (line 655) and source node 111-1 may respond by releasing the wireless resources used by source node 111 -1 to communicate with UE 101 (block 660).

As used herein, the term "circuitry," "processing circuitry," or "logic" may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide thedescribed functionality. In some embodiments, the circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, circuitry may include logic, at least partially operable in hardware.

Embodiments described herein may be implemented into 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, the 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 coupled together at least as shown. The components of the illustrated device 700 may be included in a UE or a RAN node. In some embodiments, the device 700 may include less elements (e.g., a RAN node may not utilize application circuitry 702, and instead include a processor/controller to process IP data received from an EPC). In some embodiments, the device 700 may include additional elements such as, for example, memory/ storage, display, camera, .sensor, or input/output (I/O) interface In other embodiments, the components described below may be included in more than one device (e.g., said circuitries may be separately included in more than one device for Cloud-RAN (C-RAN) implementations).

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

The baseband circuitry 704 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 704 may include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 706 and to generate baseband signals for a transmit signal path of the RF circuitry 706. Baseband processing circuity 704 may interface with the application circuitry 702 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 706. For example, in some embodiments, the baseband circuitry 704 may include a third generation (3G) baseband processor 704 A, a fourth generation (4G) baseband processor 704B, a fifth generation (5G) baseband processor 704C, or other baseband processor(s) 704D for other existing generations, generations in development or to be developed in the future (e.g., second generation (2G), sixth generation (6G), etc.). The baseband circuitry 704 (e.g., one or more of baseband processors 704 A-D) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 706. In other embodiments, some or all of the functionality of baseband processors 704 A-D may be included in modules stored in the memory 704G and executed via a Central Processing Unit (CPU) 704E. The radio control functions ,may include, but are not limited to, signal modulation/demodulation

encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry 704 may include Fast-Fourier Transform (FFT), precoding, or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the 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 functionality are not limited to these examples and may include other suitable functionality in other embodiments.

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

In some embodiments, the baseband circuitry 704 may provide for communication compatible withone or more radio technologies. For example, in some embodiments, the baseband circuitry 704 may support communication with an evolved universal terrestrial radio access network (EUTRAN) or other wireless metropolitan area networks (WMAN), awireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 704 is configured to support radio communications of more than one wireless .protocol may be referred to as multi-mode baseband circuitry

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

In some embodiments, the receive signal path of the RF circuitry 706 may include mixer circuitry 706a, amplifier circuitry 706b and filter circuitry 706c. In some embodiments, the transmit signal path of the RF circuitry 706 may include filter circuitry 706c and mixer circuitry 706a. RF circuitry 706 may also include synthesizer circuitry 706d for synthesizing a frequency for use by the mixer circuitry 706a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 706a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 708 based on the synthesized frequency provided by synthesizer circuitry 706d. The amplifier circuitry 706b may be configured to amplify the down-converted signals and the filter circuitry 706c may be a low-pass filter (LPF) or band-pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 704 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 706a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect. In some embodiments, the mixer circuitry 706a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 706d to generate RF output signals for the FEM circuitry 708. The baseband signals may be provided by the baseband circuitry 704 and may be filtered by filter circuitry 706c.

In some embodiments, the mixer circuitry 706a of the receive signal path and the mixer circuitry 706a of the transmit signal path may include two or more mixers and may be arranged for quadrature downconversion and upconversion, respectively. In some embodiments, the mixer circuitry 706a of the receive signal path and the mixer circuitry 706a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 706a of the receive signal path and the mixer circuitry 706a may be arranged for direct

downconversion and direct upconversion, respectively. In some embodiments, the mixer circuitry 706a of the receive signal path and the mixer circuitry 706a of the transmit signal path may be configured for super-heterodyne operation.

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

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

In some embodiments, the synthesizer circuitry 706d may be a fractional-N synthesizer or a fractional N/N+l synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 706d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

The synthesizer circuitry 706d may be configured to synthesize an output frequency for use by the mixer circuitry 706a of the RF circuitry 706 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 706d may be a fractional N/N+l synthesizer. In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input may be provided by either the baseband circuitry 704 or the applications processor 702 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 702.

Synthesizer circuitry 706d of the RF circuitry 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 modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DP A). In some embodiments, the DMD may be configured to divide the input signal by either N or N+1 (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, 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, synthesizer circuitry 706d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some embodiments, the RF circuitry 706 may include an IQ/polar converter.

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

In some embodiments, the FEM circuitry 708 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include an LNA to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 706). The transmit signal path of the FEM circuitry 708 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 706), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 710).

In some embodiments, the PMC 712 may manage power provided to the baseband circuitry 704. In particular, the PMC 712 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 712 may often be included when the device 700 is capable of being powered by a battery, for example, when the device is included in a UE. The PMC 712 may increase the power conversion efficiency while providing desirable implementation size and heat dissipation characteristics.

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

In some embodiments, the PMC 712 may control, or otherwise be part of, various power saving mechanisms of the device 700. For example, if the device 700 is in an

RRC_Connected state, where it is still connected to the RAN node as it expects to receive traffic shortly, then it may enter a state known as Discontinuous Reception Mode (DRX) after a period of inactivity. During this state, the device 700 may power down for brief intervals of time and thus save power.

If there is no data traffic activity for an extended period of time, then the device 700 may transition off to an RRC Idle state, where it disconnects from the network and does not perform operations such as channel quality feedback, handover, etc. The device 700 goes into a very low power state and it performs paging where again it periodically wakes up to listen to the network and then powers down again. The device 700 may not receive data in this state, in order to receive data, it must transition back to RRC Connected state.

An additional power saving mode may allow a device to be unavailable to the network for periods longer than a paging interval (ranging from seconds to a few hours). During this time, the device is totally unreachable to the network and may power down completely. Any data sent during this time incurs a large delay and it is assumed the delay is acceptable. Processors of the application circuitry 702 and processors of the baseband circuitry 704 may be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 704, alone or in combination, may be used execute Layer 3, Layer 2, or Layer 1 functionality, while processors of the application circuitry 704 may utilize data (e.g., packet data) received from these layers and further execute Layer 4 functionality (e.g., transmission communication protocol (TCP) and user datagram protocol (UDP) layers). As referred to herein, Layer 3 may comprise a radio resource control (RRC) layer, described in further detail below. As referred to herein, Layer 2 may comprise a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer, described in further detail below. As referred to herein, Layer 1 may comprise a physical (PHY) layer of a UE/RAN node, described in further detail below.

Fig. 8 illustrates example interfaces of baseband circuitry in accordance with some embodiments. As discussed above, the baseband circuitry 704 of Fig. 7 may comprise processors 704A-704E and a memory 704G utilized by said processors. Each of the processors 704A-704E may include a memory interface, respectively, to send/receive data to/from the memory 704G.

The baseband circuitry 804 may further include one or more interfaces to

communicatively couple to other circuitries/devices, such as a memory interface 812 (e.g., an interface to send/receive data to/from memory external to the baseband circuitry 704), an application circuitry interface 814 (e.g., an interface to send/receive data to/from the application circuitry 702 of Fig. 7), an RF circuitry interface 816 (e.g., an interface to send/receive data to/from RF circuitry 706 of Fig. 7), a wireless hardware connectivity interface 818 (e.g., an interface to send/receive data to/from Near Field Communication (NFC) components, Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication components), and a power management interface 820 (e.g., an interface to send/receive power or control signals to/from the PMC 712).

Fig. 9 is a block diagram illustrating components, according to some example embodiments, able to read instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium) and perform any one or more of the methodologies discussed herein. Specifically, Fig. 9 shows a diagrammatic 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, each of which may be communicatively coupled via a bus 940. For embodiments where node virtualization (e.g., NFV) is utilized, a hypervisor 902 may be executed to provide an execution environment for one or more network slices/sub-slices to utilize the hardware resources 900

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

The memory/storage devices 920 may include main memory, disk storage, or any suitable combination thereof. The memory/storage devices 920 may include, but are 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.

The communication resources 930 may include interconnection or network interface components or other suitable devices to communicate with one or more peripheral devices 904 or one or more databases 906 via a network 908. For example, the communication resources 930 may include wired communication components (e.g., for coupling via a Universal Serial Bus (USB)), cellular communication components, NFC components,

Bluetooth® components (e.g., Bluetooth® Low Energy), Wi-Fi® components, and other communication components.

Instructions 950 may comprise software, a program, an application, an applet, an app, or other executable code for causing at least any of the processors 910 to perform any one or more of the methodologies discussed herein. The instructions 950 may reside, completely or partially, within at least one of the processors 910 (e.g., within the processor's cache memory), the memory/storage devices 920, or any suitable combination thereof. Furthermore, any portion of the instructions 950 may be transferred to the hardware resources 900 from any combination of the peripheral devices 904 or the databases 906. Accordingly, the memory of processors 910, the memo ry/sto rage devices 920, the peripheral devices 904, and the databases 906 are examples of computer-readable and machine-readable media.

A number of examples, relating to embodiments of the techniques described above, will next be given. In a first example, an apparatus of a Radio Access Network (RAN) node, may comprise: an interface to radio frequency (RF) circuitry; and one or more processors to: insert a sequence number (SN) into each user data packet, of the plurality of user data packets, directed toward a User Equipment (UE) connected to the RAN node, the SN being based on a relative sequential position of each user data packet of the plurality of user data packets; and prior to causing at least one user data packet, of the plurality of user data packets, to be communicated to the UE via the RF circuitry, determine that the UE is to be transferred to a target RAN node as part of a handover procedure, and cause the at least user data packet, along with an indication of how the at least one data packet was to be communicated, by the RAN node, to the UE, prior to the handover procedure, to be transferred to the target RAN node during the handover procedure

In example 2, the subject matter of example 1, or any of the examples herein, wherein the SN of each user data packet is also based on a data radio bearer (DRB) allocated, by the RAN, for communicating the plurality of user data packets to the UE.

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

In example 4, the subject matter of example 1, or any of the examples herein, wherein the SN of each user data packet is also based on a Quality of Service (QoS) associated with communicating the plurality of user data packets to the UE..

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

In example 6, the subject matter of example 1, or any of the examples herein, wherein the one or more processors are to cause the at least user data packet to be transferred to the target RAN node based on the RAN node having not caused the at least one user data packet to be sent to the UE.

In example 7, the subject matter of example 1, or any of the examples herein, wherein the one or more processors are to cause the at least user data packet to be transferred to the target RAN node based on the RAN node having not received an acknowledgement message, from the UE, regarding the at least one user data packet.

In example 8, the subject matter of example 1, or any of the examples herein, wherein the one or more processors are to cause the at least user data packet to be transferred to the target RAN node based on the RAN node having not received an acknowledgement message, from the UE, regarding a user data packet preceding the at least one user data packet. In example 9, an apparatus of a Radio Access Network (RAN) node may comprise: an interface to radio frequency (RF) circuitry; and one or more processors to: receive, from a source RAN node of a handover procedure, a 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, including a Sequence Number (SN) based on a relative sequential position of each user data packet of the plurality of user data packets; determine a data radio bearer (DRB) for communicating the plurality of user data packets to the UE; receive, via the interface to the RF circuitry and as part of the handover procedure, an indication that the UE is ready to communicate with the RAN node; and cause, via interface to the RF circuitry, the plurality of user data packets to be communicated to the UE using the DRB.

In example 10, the subject matter of example 9, or any of the examples herein, wherein the SN of each user data packet is also based on a data radio bearer (DRB) allocated, by the source RAN node, to communicating the plurality of user data packets to the UE.

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

In example 12, the subject matter of example 11, or any of the examples herein, wherein the one or more processors are to determine the DRB based on the identifier, such that the one or more processors are to cause the plurality of user data packets to be communicated to the UE using the DRB allocated by the source RAN node.

In example 13, the subject matter of example 11, or any of the examples herein, wherein: the DRB for communicating the plurality of user data packets to the UE is distinct from the DRB allocated by the source RAN node, and the one or more processors are further to: map the SN to another sequence number (SN), which is based on the DRB for communicating the plurality of user data packets; and insert the another sequence number (SN) into each user data packet of the plurality of user data packets.

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

In example 15, the subject matter of example 14, or any of the examples herein, wherein the one or more processors are further to: determine a Quality of Service (QoS) with which the RAN node is to communicate the plurality of user data packets to the UE; and map an identifier associated with the QoS, included in the plurality of user data packets, to the QoS with which the RAN node is to communicate the plurality of user data packets to the UE.

In example 16, the subject matter of example 9, or any of the examples herein, wherein the one or more processors are further to: determine that the UE has received the plurality of user data packets; determine another DRB, which is distinct from the DRB, for communicating the UE; and cause the another DRB, instead of the DRB, to be used to communicate with the UE.

In example 17, the subject matter of example 9, or any of the examples herein, wherein, prior to causing the plurality of user data packets to be communicated to the UE, the one or more processors are further to: determine the another DRB; cause configuration information, for switching to the another DRB, to be sent to the UE; and use the another BRD to communicate with the UE after communicating the plurality of user data packets to the UE.

In example 18, the subject matter of example 9, or any of the examples herein, 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.

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

In example 20, the subject matter of example 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 example 1 or 9, or any of the examples herein, wherein the plurality of user data packets are communicated via a user plane of a wireless telecommunication network.

In example 22, an apparatus of a User Equipment (UE) may comprise: an interface to radio frequency (RF) circuitry; and one or more processors to: receive, via the interface to the RF circuitry, a first plurality of user data packets from a first Radio Access Network (RAN) node, each user data packet, of the first plurality of user data packets including a sequence number (SN) based on a sequential position of each user data packet of the first plurality of user data packets; receive, via the interface to the RF circuitry, instruction to participate in a handover procedure involving the first RAN node and a second RAN node; receive, via the interface to the RF circuitry and as part of the handover procedure, a second plurality of user data packets from the second RAN node, each user data packet, of the second plurality of user data packets, including a SN based on a sequential position of each user data packet relative to the first plurality of user data packets and the second plurality of user data packets; and merge the first plurality of user data packets with the second plurality of user data packets based on the SN of each user data packet of the first plurality of user data packets and the second plurality of user data packets.

In example 23, the subject matter of example 22, or any of the examples herein, wherein the one or more processors are further to: cause, based on the instructions, a message to be communicated, via the interface to the RF circuitry and to the 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 of the examples herein, wherein the one or more processors are further to: determine, based on the SN of each user data packet of the first plurality of user data packets and the second plurality of user data packets, whether a transmission failure has occurred; and communicate, to the second RAN node, a retransmission request for user data packets corresponding to the transmission failure.

In example 25, the subject matter of example 22, or any of the examples herein, wherein the one or more processors are further to: delete, at least one user data packet, of the first plurality of user data packets, based on the at least one user data packet based on the UE having not transmitted an acknowledgement message, to the first RAN node, for the at least one user data packet; and receive, as part of the second plurality of user data packets from the second RAN node, another copy of the at least one user data packet.

In example 26, the subject matter of example 25, or any of the examples herein, wherein the one or more processors are further to: delete, another user data packet, of the first plurality of user data packets, based on the another user data packet having a SN that is subsequent to a SN of the at least one user data packet.

In example 27, the subject matter of example 22, or any of the examples herein, wherein the one or more processors are further to: determine that all of the first plurality of user data packets and the second plurality of user data packets have been received, and cause an end marker packet to be communicated to the second RAN indicating that the all of the first plurality of user data packets and the second plurality of 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 sequence number (SN) into each user data packet, of the plurality of user data packets, directed toward a User Equipment (UE) connected to the RAN node, the SN being based on a relative sequential position of each user data packet of the plurality of user data packets; and prior to causing at least one user data packet, of the plurality of user data packets, to be communicated to the UE, determine that the UE is to be transferred to a target RAN node as part of a handover procedure, and cause the at least user data packet, along with an indication of how the at least one data packet was to be communicated, by the RAN node, to the UE, prior to the handover procedure, to be transferred to the target RAN node during the handover procedure.

In example 29, the subject matter of example 28, or any of the examples herein, wherein the SN of each user data packet is also based on a data radio bearer (DRB) allocated, by the RAN, for communicating the plurality of user data packets to the UE.

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

In example 31, the subject matter of example 28, or any of the examples herein, wherein the SN of each user data packet is also based on a Quality of Service (QoS) associated with communicating the plurality of user data packets to the UE.

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

In example 33, the subject matter of example 28, or any of the examples herein, wherein the one or more processors are to cause the at least user data packet to be transferred to the target RAN node based on the RAN node having not caused the at least one user data packet to be sent to the UE.

In example 34, the subject matter of example 28, or any of the examples herein, wherein the one or more processors are to cause the at least user data packet to be transferred to the target RAN node based on the RAN node having not received an acknowledgement message, from the UE, regarding the at least one user data packet.

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

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: receive, from a source RAN node of a handover procedure, a 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, including a Sequence Number (SN) based on a relative sequential position of each user data packet of the plurality of user data packets; determine a data radio bearer (DRB) for communicating the plurality of user data packets to the UE; receive, as part of the handover procedure, an indication that the UE is ready to communicate with the RAN node; and cause the plurality of user data packets to be communicated to the UE using the DRB.

In example 37, the subject matter of example 36, or any of the examples herein, wherein the SN of each user data packet is also based on a data radio bearer (DRB) allocated, by the source RAN node, to communicating the plurality of user data packets to the UE.

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

In example 39, the subject matter of example 38, or any of the examples herein, wherein the one or more processors are to determine the DRB based on the identifier, such that the one or more processors are to cause the plurality of user data packets to be communicated to the UE using the DRB allocated by the source RAN node.

In example 40, the subject matter of example 38, or any of the examples herein, wherein: the DRB for communicating the plurality of user data packets to the UE is distinct from the DRB allocated by the source RAN node, and the one or more processors are further to: map the SN to another sequence number (SN), which is based on the DRB for communicating the plurality of user data packets; and insert the another sequence number (SN) into each user data packet of the plurality of user data packets.

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

In example 42, the subject matter of example 41, or any of the examples herein, wherein the one or more processors are further to: determine a Quality of Service (QoS) with which the RAN node is to communicate the plurality of user data packets to the UE; and map an identifier associated with the QoS, included in the plurality of user data packets, to the QoS with which the RAN node is to communicate the plurality of user data packets to the UE.

In example 43, the subject matter of example 36, or any of the examples herein, wherein the one or more processors are further to: determine that the UE has received the plurality of user data packets; determine another DRB, which is distinct from the DRB, for communicating the UE; and cause the another DRB, instead of the DRB, to be used to communicate with the UE.

In example 44, the subject matter of example 36, or any of the examples herein, wherein, prior to causing the plurality of user data packets to be communicated to the UE, the one or more processors are further to: determine the another DRB; cause configuration information, for switching to the another DRB, to be sent to the UE; and use the another BRD to communicate with the UE after communicating the plurality of user data packets to the UE.

In example 45, the subject matter of example 36, or any of the examples herein, 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.

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

In example 47, the subject matter of example 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 example 28 or 36, or any of the examples herein, wherein the plurality of user data packets are communicated via a user plane of a wireless telecommunication 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: receive a first plurality of user data packets from a first Radio Access Network (RAN) node, each user data packet, of the first plurality of user data packets including a sequence number (SN) based on a sequential position of each user data packet of the first plurality of user data packets;

receive instruction to participate in a handover procedure involving the first RAN node and a second RAN node; receive, as part of the handover procedure, a second plurality of user data packets from the second RAN node, each user data packet, of the second plurality of user data packets, including a SN based on a sequential position of each user data packet relative to the first plurality of user data packets and the second plurality of user data packets; and merge the first plurality of user data packets with the second plurality of user data packets based on the SN of each user data packet of the first plurality of user data packets and the second plurality of 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 to: cause, based on the instructions, a message to be communicated, to the second RAN node, indicating that the UE is configured to communicate with the second RAN node.

In example 51, the subject matter of example 49, or any of the examples herein, wherein the one or more processors are further to: determine, based on the SN of each user data packet of the first plurality of user data packets and the second plurality of user data packets, whether a transmission failure has occurred; and communicate, to the second RAN node, a retransmission request for user data packets corresponding to the transmission failure In example 52 the subject matter of example 49, or any of the examples herein, wherein the one or more processors are further to: delete, at least one user data packet, of the first plurality of user data packets, based on the at least one user data packet based on the UE having not transmitted an acknowledgement message, to the first RAN node, for the at least one user data packet; and receive, as part of the second plurality of user data packets from the second RAN node, another copy of the at least one user data packet.

In example 53, the subject matter of example 52, or any of the examples herein, wherein the one or more processors are further to: delete, another user data packet, of the first plurality of user data packets, based on the another user data packet having a SN that is subsequent to a SN of the at least one user data packet.

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

In example 55, an apparatus of a Radio Access Network (RAN) node may comprise: means for inserting a sequence number (SN) into each user data packet, of the plurality of user data packets, directed toward a User Equipment (UE) connected to the RAN node, the SN being based on a relative sequential position of each user data packet of the plurality of user data packets; and prior to causing at least one user data packet, of the plurality of user data packets, to be communicated to the UE, means for determining that the UE is to be transferred to a target RAN node as part of a handover procedure, and means for causing the at least user data packet, along with an indication of how the at least one data packet was to be communicated, by the RAN node, to the UE, prior to the handover procedure, to be transferred to the target RAN node during the handover procedure.

In example 56, the subject matter of example 55, or any of the examples herein, wherein the SN of each user data packet is also based on a data radio bearer (DRB) allocated, by the RAN, for communicating the plurality of user data packets to the UE.

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

In example 58, the subject matter of example 55, or any of the examples herein, wherein the SN of each user data packet is also based on a Quality of Service (QoS) associated with communicating the plurality of user data packets to the UE.

In example 59, the subject matter of example 58, or any of the examples herein, wherein the indication includes an identifier of a QoS level associated with communicating 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: means for causing the at least user data packet to be transferred to the target RAN node based on the RAN node having not caused the at least one user data packet to be sent to the UE.

In example 61, the subject matter of example 55, or any of the examples herein, further comprising: mean for causing the at least user data packet to be transferred to the target RAN node based on the RAN node having not received an acknowledgement message, from the UE, regarding the at least one user data packet.

In example 62, the subject matter of example 55, or any of the examples herein, further comprising: means for causing the at least user data packet to be transferred to the target RAN node based on the RAN node having not received an acknowledgement message, from the UE, regarding a user data packet preceding the at least one user data packet.

In example 63, an apparatus of a Radio Access Network (RAN) node may comprise: means for receiving, from a source RAN node of a handover procedure, a 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, including a Sequence Number (SN) based on a relative sequential position of each user data packet of the plurality of user data packets; means for determining a data radio bearer (DRB) for communicating the plurality of user data packets to the UE; means for receiving, as part of the handover procedure, an indication that the UE is ready to communicate with the RAN node; and means for causing the plurality of user data packets to be communicated to the UE using the DRB In example 64, the subject matter of example 63, or any of the examples herein, wherein the SN of each user data packet is also based on a data radio bearer (DRB) allocated, by the source RAN node, to communicating the plurality of user data packets to the UE.

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

In example 66, the subject matter of example 658, or any of the examples herein, further comprising: means for determining the DRB based on the identifier, such that the one or more processors are to cause the plurality of user data packets to be communicated to the UE using the DRB allocated by the source RAN node.

In example 67, the subject matter of example 65, or any of the examples herein, wherein: the DRB for communicating the plurality of user data packets to the UE is distinct from the DRB allocated by the source RAN node, and the apparatus further comprising: means for mapping the SN to another sequence number (SN), which is based on the DRB for communicating the plurality of user data packets; and means for inserting the another sequence number (SN) into each user data packet of the plurality of user data packets.

In example 68, the subject matter of example 63, or any of the examples herein, wherein the SN of each user data packet is based on a Quality of Service (QoS) associated with the source RAN node communicating 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 the RAN node is to communicate the plurality of user data packets to the UE; and means for 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 communicate 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 determining another DRB, which is distinct from the DRB, for communicating the UE; and means for causing the another DRB, instead of the DRB, to be used to communicate with the UE.

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

In example 72, the subject matter of example 63, or any of the examples herein, further comprising: means for receiving 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.

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

In example 74, the subject matter of example 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 example 55 or 66, or any of the examples herein, wherein the plurality of user data packets are communicated via a user plane of a wireless telecommunication network.

In example 76, a method, performed by a Radio Access Network (RAN) node may comprise: inserting a sequence number (SN) into each user data packet, of the plurality of user data packets, directed toward a User Equipment (UE) connected to the RAN node, the SN being based on a relative sequential position of each user data packet of the plurality of user data packets; and prior to causing at least one user data packet, of the plurality of user data packets, to be communicated to the UE, determining that the UE is to be transferred to a target RAN node as part of a handover procedure, and causing the at least user data packet, along with an indication of how the at least one data packet was to be communicated, by the RAN node, to the UE, prior to the handover procedure, to be transferred to the target RAN node during the handover procedure.

In example 77, the subject matter of example 76, or any of the examples herein, wherein the SN of each user data packet is also based on a data radio bearer (DRB) allocated, by the RAN, for communicating the plurality of user data packets to the UE.

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

In example 79, the subject matter of example 76, or any of the examples herein, wherein the SN of each user data packet is also based on a Quality of Service (QoS) associated with communicating the plurality of user data packets to the UE. In example 80, the subject matter of example 79, or any of the examples herein, wherein the indication includes an identifier of a QoS level associated with communicating 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 user data packet to be transferred to the target RAN node based on the RAN node having not received an acknowledgement message, from the UE, regarding the at least one user data packet.

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

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

In the preceding 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 additional embodiments may be implemented, without departing from the broader scope as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.

For example, while series of signals and/or operations have been described with regard to Figs. 2-6 the order of the signals/operations may be modified in other

implementations. Further, non-dependent signals may be performed in parallel.

It will be apparent that example aspects, as described above, may be implemented in many different forms of software, firmware, and hardware in the implementations illustrated in the figures. The actual software code or specialized control hardware used to implement these aspects should not be construed as limiting. Thus, the operation and behavior of the aspects were described without reference to the specific software code— it being understood that software and control hardware could be designed to implement the aspects based on the description herein.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to be limiting. In fact, 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 described as such. An instance of the use of the term "and," as used herein, does not necessarily preclude the interpretation that the phrase "and/or" was intended in that instance. Similarly, an instance of the use of the term "or," as used herein, does not necessarily preclude the interpretation that the phrase "and/or" was intended in that instance. Also, as used herein, the article "a" is intended to include one or more items, and may be used interchangeably with the phrase "one or more. " Where only one item is intended, the terms "one," "single," "only," or similar language is used.

Claims

WHAT IS CLAIMED IS:

1. An apparatus of a Radio Access Network (RAN) node, the apparatus comprising: an interface to radio frequency (RF) circuitry; and

one or more processors to:

insert a sequence number (SN) into each user data packet, of the plurality of user data packets, directed toward a User Equipment (UE) connected to the RAN node, the SN being based on a relative sequential position of each user data packet of the plurality of user data packets; and

prior to causing at least one user data packet, of the plurality of user data packets, to be communicated to the UE via the RF circuitry,

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

cause the at least user data packet, along with an indication of how the at least one data packet was to be communicated, by the RAN node via the interface to the RF circuitry, to the UE, prior to the handover procedure, to be transferred to the target RAN node during the handover procedure.

2. The apparatus of claim 1, wherein the SN of each user data packet is also based on a data radio bearer (DRB) allocated, by the RAN, for communicating the plurality of user data packets to the UE.

3. The apparatus of claim 2, wherein the indication includes an identifier of the DRB.

4. The apparatus of claim 1, wherein the SN of each user data packet is also based on a Quality of Service (QoS) associated with communicating the plurality of user data packets to the UE.

5. The apparatus of claim 4, wherein the indication includes an identifier of a QoS level associated with communicating the plurality of user data packets to the UE.

6. The apparatus of claim 1, 3, or 5, wherein the one or more processors are to cause the at least user data packet to be transferred to the target RAN node based on the RAN node having not caused the at least one user data packet to be sent to the UE.

7. The apparatus of claim 1, 3, or 5, wherein the one or more processors are to cause the at least user data packet to be transferred to the target RAN node based on the RAN node having not received an acknowledgement message, from the UE, regarding the at least one user data packet.

8. The apparatus of claim 1, 3, or 5, wherein the one or more processors are to cause the at least user data packet to be transferred to the target RAN node based on the RAN node having not received an acknowledgement message, from the UE, regarding a user data packet preceding the at least one user data packet.

9. An apparatus of a Radio Access Network (RAN) node, the apparatus comprising: an interface to radio frequency (RF) circuitry; and one or more processors to:

receive, from a source RAN node of a handover procedure, a 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, including a

Sequence Number (SN) based on a relative sequential position of each user data packet of the plurality of user data packets;

determine a data radio bearer (DRB) for communicating the plurality of user data packets to the UE;

receive, via the interface to the RF circuitry and as part of the handover procedure, an indication that the UE is ready to communicate with the RAN node; and cause, via interface to the RF circuitry, the plurality of user data packets to be communicated to the UE using the DRB.

10. The apparatus of claim 9, wherein the SN of each user data packet is also based on a data radio bearer (DRB) allocated, by the source RAN node, to communicating the plurality of user data packets to the UE.

1 1. The apparatus of claim 10, wherein each user data packet, of the plurality of user data packets, includes an identifier associated with the DRB allocated by the source RAN.

12. The RAN node of claim 1 1, wherein the one or more processors are to determine the DRB based on the identifier, such that the one or more processors are to cause the plurality of user data packets to be communicated to the UE using the DRB allocated by the source RAN node.

13. The RAN node of claim 1 1, wherein:

the DRB for communicating the plurality of user data packets to the UE is distinct from the DRB allocated by the source RAN node, and

the one or more processors are further to:

map the SN to another sequence number (SN), which is based on the DRB for communicating the plurality of user data packets; and

insert the another sequence number (SN) into each user data packet of the plurality of user data packets.

14. The apparatus of claim 9, wherein the SN of each user data packet is based on a Quality of Service (QoS) associated with the source RAN node communicating the plurality of user data packets to the UE.

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

determine a Quality of Service (QoS) with which the RAN node is to communicate the plurality of user data packets to the UE; and

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

16. The apparatus of claim 9, 11, or 15, wherein the one or more processors are further to: determine that the UE has received the plurality of user data packets;

determine another DRB, which is distinct from the DRB, for communicating the UE; and

cause the another DRB, instead of the DRB, to be used to communicate with the UE.

17. The apparatus of claim 9, 11, or 15, wherein, prior to causing the plurality of user data packets to be communicated to the UE, the one or more processors are further to:

determine the another DRB;

cause configuration information, for switching to the another DRB, to be sent to the UE; and use the another BRD to communicate with the UE after communicating the plurality of user data packets to the UE.

18. The RAN node of claim 9, 11, or 15, 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.

19. The RAN node of claim 9, 11, or 15, wherein the one or more processors are further to receive an end marker packet indicating the UE has received the plurality of user data packets.

20. An apparatus as in claim 1 or 9, wherein the RAN node comprises a New Radio (NR) base station.

21. An apparatus as in claim 1 or 9, wherein the plurality of user data packets are communicated via a user plane of a wireless telecommunication network.

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

an interface to radio frequency (RF) circuitry; and

one or more processors to:

receive, via the interface to the RF circuitry, a first plurality of user data packets from a first Radio Access Network (RAN) node, each user data packet, of the first plurality of user data packets including a sequence number (SN) based on a sequential position of each user data packet of the first plurality of user data packets; receive, via the interface to the RF circuitry, instruction to participate in a handover procedure involving the first RAN node and a second RAN node;

receive, via the interface to the RF circuitry and as part of the handover procedure, a second plurality of user data packets from the second RAN node, each user data packet, of the second plurality of user data packets, including a SN based on a sequential position of each user data packet relative to the first plurality of user data packets and the second plurality of user data packets; and merge the first plurality of user data packets with the second plurality of user data packets based on the SN of each user data packet of the first plurality of user data packets and the second plurality of user data packets.

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

cause, based on the instructions, a message to be communicated, via the interface to the RF circuitry and to the second RAN node, indicating that the UE is configured to communicate with the second RAN node.

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

determine, based on the SN of each user data packet of the first plurality of user data packets and the second plurality of user data packets, whether a transmission failure has occurred; and

communicate, to the second RAN node, a retransmission request for user data packets corresponding to the transmission failure.

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

delete, at least one user data packet, of the first plurality of user data packets, based on the at least one user data packet based on the UE having not transmitted an acknowledgement message, to the first RAN node, for the at least one user data packet; and

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