PDU Set Information Forwarding During Mobility Events

Abstract

A target cell receives a handover message for a user equipment (UE) originating from a source cell, and receives buffered data for a set of one or more protocol data units (PDUs) in transition between the source cell and the UE. The target cell receives PDU set information for the one or more PDU sets, and communicates with the UE based on the PDU set information for the one or more PDU sets. The source cell transmits or receives a portion of the set of PDUs with the UE. The apparatus initiates a handover of the UE to a target cell, provides buffer data for the set of PDUs to the target cell, and provides PDU set information for the set of PDUs to the target cell.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit and priority of U.S. Provisional Application Serial No. 63 / 381,751, filed on October 31, 2022, entitled "PDU Set Information Forwarding During Mobility Events", and U.S. Non - Provisional Patent Application Serial No. 18 / 469,228, filed on September 18, 2023, entitled "PDU SET INFORMATION FORWARDING DURING MOBILITY EVENTS", which are hereby incorporated by reference in their entireties. Technical Field

[0003] The present disclosure generally relates to communication systems, and more particularly to wireless communication including protocol data unit (PDU) sets. Background Art

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. A typical wireless communication system may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code - division multiple access (CDMA) systems, time - division multiple access (TDMA) systems, frequency - division multiple access (FDMA) systems, orthogonal frequency - division multiple access (OFDMA) systems, single - carrier frequency - division multiple access (SC - FDMA) systems, and time - division synchronous code - division multiple access (TD - SCDMA) systems.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at the urban, national, regional, and even global levels. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continuous mobile broadband evolution promulgated by the 3rd Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., related to the Internet of Things (IoT)), and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine - type communication (mMTC), and ultra - reliable low - latency communication (URLLC). Some aspects of 5G NR may be based on the 4G Long - Term Evolution (LTE) standard. Further improvements to 5G NR technology are needed. These improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the Invention

[0006] A simplified summary of one or more aspects is presented below to provide a basic understanding of these aspects. This Summary of the Invention is not an extensive overview of all contemplated aspects. It neither identifies key or critical elements of all aspects nor describes the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0007] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus for wireless communication at a target cell are provided. The apparatus receives a handover message for a user equipment (UE) from a source cell, and receives buffered data for one or more sets of protocol data units (PDUs) in transition between the source cell and the UE. The apparatus receives PDU set information for the one or more sets of PDUs, and communicates with the UE based on the PDU set information for the one or more sets of PDUs.

[0008] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus for wireless communication at a source cell are provided. The apparatus transmits or receives a portion of a set of PDUs with the UE. The apparatus initiates a handover of the UE to a target cell, provides buffered data for the set of PDUs to the target cell, and provides PDU set information for the set of PDUs to the target cell.

[0009] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus for wireless communication at a UE are provided. The apparatus transmits a portion of an uplink set of PDUs to a source cell, provides PDU set information for the uplink set of PDUs to a target cell to which the UE is handing over from the source cell, and transmits the remainder of the uplink set of PDUs to the target cell after the handover to the target cell.

[0010] To achieve the foregoing and related purposes, one or more aspects include the features described in full below and particularly pointed out in the claims. The following description and the drawings set forth in detail some illustrative features of one or more aspects. However, these features are indicative of only some of the various ways in which the principles of the various aspects may be employed. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network in accordance with various aspects of the present disclosure.

[0012] Figure 2A is a diagram illustrating an example of a first frame in accordance with various aspects of the present disclosure.

[0013] Figure 2BIs a diagram illustrating an example of a downlink (DL) channel within a subframe according to various aspects of the present disclosure.

[0014] Figure 2C Is a diagram illustrating an example of a second frame according to various aspects of the present disclosure.

[0015] Figure 2D Is a diagram illustrating an example of an uplink (UL) channel within a subframe according to various aspects of the present disclosure.

[0016] Figure 3 Is a diagram illustrating an example of a base station and a user equipment (UE) in an access network according to various aspects of the present disclosure.

[0017] Figure 4 Is a diagram illustrating the timing aspects of an extended reality (XR) service.

[0018] Figure 5 Is a diagram illustrating aspects of a PDU set according to various aspects of the present disclosure.

[0019] Figure 6 Illustrates a communication flow including a handover of a UE from a source cell to a target cell and communication of PDUs in a PDU set according to various aspects of the present disclosure.

[0020] Figure 7 Illustrates a communication flow including a handover of a UE from a source cell to a target cell and communication of PDUs in a PDU set according to various aspects of the present disclosure.

[0021] Figure 8 Illustrates a communication flow including a handover of a UE from a source cell to a target cell and communication of PDUs in a PDU set according to various aspects of the present disclosure.

[0022] Figure 9 Illustrates a communication flow including a handover of a UE from a source cell to a target cell and communication of PDUs in a PDU set according to various aspects of the present disclosure.

[0023] Figure 10 Is a flowchart of a method for wireless communication at a target cell according to various aspects of the present disclosure.

[0024] Figure 11 Is a flowchart of a method for wireless communication at a source cell according to various aspects of the present disclosure.

[0025] Figure 12 Is a flowchart of a method for wireless communication at a UE according to various aspects of the present disclosure.

[0026] Figure 13Is a diagram illustrating an example of a hardware implementation for exemplifying an apparatus and / or a UE.

[0027] Figure 14 Is a diagram illustrating an example of a hardware implementation for exemplifying a network entity.

[0028] Figure 15 Is a diagram illustrating an example of a hardware implementation for exemplifying a network entity. Detailed Description

[0029] A PDU set is a set or group of PDUs that are delivered as an integrated unit between the radio access network (RAN) and an application at the UE. For example, the PDUs in a PDU set share common quality of service (QoS) attributes, such as a PDU set delay budget (PSDB), a PDU set error rate (PSER), and other examples of QoS attributes that can be common to the PDUs in the PDU set. An example of a PDU set is data for a video frame or for a slice within a video frame. Different PDU sets can have different types of decoding criteria, which can be referred to as PDU set content criteria. As a first example of a decoding criterion (or PDU set content criterion), if any PDU in a PDU set is lost (e.g., not accurately received at the receiver), then the entire PDU set may become obsolete. As a second example of a decoding criterion (or PDU set content criterion), the received PDUs in a PDU set can be considered good (e.g., usable by the application) until the first PDU loss occurs (e.g., until the first PDU in the PDU set is lost or not received by the receiver). As a third example of a decoding criterion (or PDU set content criterion), the PDUs in a PDU set can be encoded using application layer forward error correction (AL-FEC), and based on the FEC redundancy ratio, the PDUs in the PDU set can be decoded when a subset of the PDUs is lost or not received. In this example, the use of AL-FEC can enable decoding of the PDU set based on a subset of the PDUs in the PDU set.

[0030] PDUs can be discarded by the UE and / or by the RAN based on a latency budget and / or a loss criterion. As part of receiving and decoding PDUs in a set of PDUs, the UE and the RAN can maintain set of PDU state information. Some events can cause a change in the connection between the network and the UE. Aspects presented herein enable a target cell in a handover of the UE to obtain set of PDU state information for an in - progress set of PDUs (e.g., a set of PDUs in transition) between the source cell and the UE. The target cell can receive buffered PDUs and can use the set of PDU state information to continue communication with the UE for the set of PDUs. Aspects presented herein, for example, improve the reliability of communication with the network and help avoid discarding a set of PDUs when a handover occurs. The increased reliability improves the user experience. As an example, the reliability of transmission and reception of PDUs for XR wireless communication can have a significant impact on the XR user experience, which can be improved by aspects of the present disclosure.

[0031] The detailed description set forth below in connection with the accompanying drawings is a description of various configurations and does not represent the only configurations in which the concepts described herein may be practiced. For a thorough understanding of the various concepts, the detailed description includes specific details. However, the concepts may be practiced without these specific details. In some instances, well - known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0032] Several aspects of a telecommunications system are presented with reference to various apparatuses and methods. These apparatuses and methods are described in the following detailed description and illustrated in the drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements can be implemented using either electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

[0033] As an example, an element, or any portion of an element, or any combination of elements can be implemented as a "processing system" that includes one or more processors. When multiple processors are implemented, the multiple processors can perform functions individually or in combination. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on a chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic components, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. One or more processors in the processing system can execute software. Software should be broadly construed to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, or any combination thereof, regardless of whether it is referred to as software, firmware, middleware, microcode, hardware description language, or other terms.

[0034] Thus, in one or more example aspects, embodiments, and / or use cases, the described functionality can be implemented in hardware, software, or any combination thereof. If implemented in software, the functionality can be stored or encoded on a computer-readable medium as one or more instructions or code. Computer-readable media includes computer storage media. Storage media can be any available media that can be accessed by a computer. By way of example, such computer-readable media can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of these types of computer-readable media, or any other medium that can be used to store computer-executable code in the form of instructions or data structures that can be accessed by a computer.

[0035] While aspects, embodiments, and / or use cases are described by way of some examples in this application, additional or different aspects, embodiments, and use cases may arise in many different arrangements and scenarios. The aspects, embodiments, and / or use cases described herein may be implemented across many different platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, the aspects, embodiments, and / or use cases may be embodied via integrated chips and other devices based on non-module components (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail / purchase devices, medical devices, artificial intelligence (AI)-enabled devices, etc.). Although some examples may or may not be specifically targeted at use cases or applications, the described examples may have broad applicability. The aspects, embodiments, and / or use cases may range from chip-level or modular components to non-modular, non-chip-level embodiments, and further to aggregated, distributed, or original equipment manufacturer (OEM) devices or systems incorporating one or more of the technologies herein. In some practical settings, devices incorporating the described aspects and features may also include additional components and features for implementing and practicing the claimed and described aspects. For example, the transmission and reception of wireless signals necessarily involve multiple components for analog and digital purposes (e.g., hardware components including antennas, RF chains, power amplifiers, modulators, buffers, processors, interleavers, adders / summers, etc.). The technologies described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, aggregated components, or disaggregated components, end-user devices, etc., of various sizes, shapes, and configurations.

[0036] The deployment of a communication system (such as a 5G NR system) can be arranged with various components or constituent parts in multiple ways. In a 5G NR system or network, network nodes, network entities, mobility elements of the network, radio access network (RAN) nodes, core network nodes, network elements, or network equipment (such as a base station (BS)) or one or more units (or one or more components) performing base station functions may be implemented in an aggregated or disaggregated architecture. For example, a BS (such as a Node B (NB), evolved NB (eNB), NR BS, 5G NB, access point (AP), transmit receive point (TRP), or cell, etc.) can be implemented as an aggregated base station (also referred to as a stand-alone BS or monolithic BS) or a disaggregated base station.

[0037] A centralized base station may be configured to utilize a radio protocol stack physically or logically integrated within a single RAN node. A split base station may be configured to utilize a protocol stack physically or logically distributed among two or more units, such as one or more central or centralized units (CUs), one or more distributed units (DUs), or one or more radio units (RUs). In some aspects, a CU may be implemented within a RAN node, and one or more DUs may be co-located with the CU, or alternatively, may be geographically or virtually distributed among one or more other RAN nodes. A DU may be implemented to communicate with one or more RUs. Each of the CU, DU, and RU may be implemented as a virtual unit, i.e., a virtual central unit (VCU), a virtual distributed unit (VDU), or a virtual radio unit (VRU).

[0038] Base station operation or network design may consider the aggregation characteristics of base station functionality. For example, a split base station may be used in an integrated access backhaul (IAB) network, an open radio access network (O-RAN, such as a network configuration initiated by the O-RAN Alliance), or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN)). Splitting may include distributing functions across two or more units at various physical locations, as well as virtualizing the functions of at least one unit, which may enable flexibility in network design. The various units of a split base station or a split RAN architecture may be configured for wired or wireless communication with at least one other unit.

[0039] Figure 1 FIG. 100 is a diagram illustrating an example of a wireless communication system and an access network. The illustrated wireless communication system includes a split base station architecture. The split base station architecture may include one or more CUs 110, which may communicate directly with a core network 120 via a backhaul link, or indirectly with the core network 120 through one or more split base station units, such as a near real-time (near RT) RAN intelligent controller (RIC) 125 via an E2 link, or a non-real-time (non RT) RIC 115 associated with a service management and orchestration (SMO) framework 105, or both. The CU 110 may communicate with one or more DUs 130 via a respective midhaul link, such as an F1 interface. The DU 130 may communicate with one or more RUs 140 via a respective fronthaul link. The RU 140 may communicate with a respective UE 104 via one or more radio frequency (RF) access links. In some embodiments, the UE 104 may be served simultaneously by multiple RUs 140.

[0040] Each unit (i.e., CU 110, DU 130, RU 140, and the near RT RIC 125, non-RT RIC 115, and SMO framework 105) may include one or more interfaces or be coupled to one or more interfaces that are configured to receive or transmit signals, data, or information (collectively referred to as signals) via a wired or wireless transmission medium. Each of the units or the associated processor or controller that provides instructions to the communication interfaces of these units may be configured to communicate with one or more of the other units via the transmission medium. For example, the units may include a wired interface that is configured to receive signals or transmit signals to one or more of the other units via a wired transmission medium. Additionally, the units may include a wireless interface that may include a receiver, transmitter, or transceiver (such as an RF transceiver) that is configured to receive and / or transmit signals to one or more of the other units via a wireless transmission medium.

[0041] In some aspects, the CU 110 may host one or more higher layer control functions. Such control functions may include Radio Resource Control (RRC), Packet Data Convergence Protocol (PDCP), Service Data Adaptation Protocol (SDAP), etc. Each control function may be implemented using an interface that is configured to communicate signals with other control functions hosted by the CU 110. The CU 110 may be configured to handle user plane functionality (i.e., Central Unit - User Plane (CU-UP)), control plane functionality (i.e., Central Unit - Control Plane (CU-CP)), or a combination thereof. In some specific implementations, the CU 110 may be logically split into one or more CU-UP units and one or more CU-CP units. When implemented in an O-RAN configuration, the CU-UP units may communicate bidirectionally with the CU-CP units via an interface such as the E1 interface. As needed, the CU 110 may be implemented to communicate with the DU 130 for network control and signaling.

[0042] The DU 130 may correspond to a logical unit that includes one or more base station functions for controlling the operation of one or more RUs 140. In some aspects, the DU 130 may host one or more of the Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and one or more high Physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation, and demodulation, etc.) at least partially according to a functional split (such as those defined by 3GPP). In some aspects, the DU 130 may also host one or more low PHY layers. Each layer (or module) may be implemented using an interface that is configured to communicate signals with other layers (and modules) hosted by the DU 130 or with the control functions hosted by the CU 110.

[0043] Lower layer functionality may be implemented by one or more RUs 140. In some deployments, the RUs 140 controlled by the DU 130 may correspond to logical nodes that host RF processing functions or low PHY layer functions (such as performing Fast Fourier Transform (FFT), Inverse FFT (iFFT), digital beamforming, Physical Random Access Channel (PRACH) extraction and filtering, etc.) or both, at least partially based on function splitting such as lower layer function splitting. In such an architecture, the RU 140 may be implemented to handle over-the-air (OTA) communication with one or more UEs 104. In some embodiments, the real-time and non-real-time aspects of the control plane and user plane communication with the RU 140 may be controlled by the corresponding DU 130. In some scenarios, this configuration may enable the implementation of the DU 130 and CU 110 in a cloud-based RAN architecture such as a vRAN architecture.

[0044] The SMO framework 105 may be configured to support the deployment and orchestration of RANs with non-virtualized network elements and virtualized network elements. For non-virtualized network elements, the SMO framework 105 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements, which may be managed via an operation and maintenance interface such as the O1 interface. For virtualized network elements, the SMO framework 105 may be configured to interact with a cloud computing platform such as the Open Cloud (O-Cloud) 190 to perform network element lifecycle management (such as instantiating virtualized network elements) via a cloud computing platform interface such as the O2 interface. Such virtualized network elements may include, but are not limited to, the CU 110, DU 130, RU 140, and the near RT RIC 125. In some embodiments, the SMO framework 105 may communicate with the hardware aspects of the 4G RAN such as the Open eNB (O-eNB) 111 via the O1 interface. Additionally, in some embodiments, the SMO framework 105 may communicate directly with one or more RUs 140 via the O1 interface. The SMO framework 105 may also include a non-RT RIC 115 configured to support the functionality of the SMO framework 105.

[0045] The non-RT RIC 115 can be configured to include logic functions that enable non-real-time control and optimization of RAN elements and resources, artificial intelligence (AI) / machine learning (ML) (AI / ML) workflows including model training and updating, or policy-based guidance of applications / features in the near-RT RIC 125. The non-RT RIC 115 can be coupled to or communicate with the near-RT RIC 125 (such as via the A1 interface). The near-RT RIC 125 can be configured to include logic functions that enable near-real-time control and optimization of RAN elements and resources via data collection and actions through an interface (such as via the E2 interface) that connects one or more CUs 110, one or more DUs 130, or both, and the O-eNB to the near-RT RIC 125.

[0046] In some embodiments, to generate the AI / ML models to be deployed in the near-RT RIC 125, the non-RT RIC 115 can receive parameters or external enrichment information from an external server. Such information can be utilized by the near-RT RIC 125 and can be received from non-network data sources or from network functions at the SMO framework 105 or at the non-RT RIC 115. In some examples, the non-RT RIC 115 or the near-RT RIC 125 can be configured to tune RAN behavior or performance. For example, the non-RT RIC 115 can monitor long-term trends and patterns of performance and employ an AI / ML model to perform corrective actions via the SMO framework 105 (such as via reconfiguration of O1) or via creating RAN management policies (such as A1 policies).

[0047] At least one of CU 110, DU 130, and RU 140 may be referred to as base station 102. Thus, base station 102 may include one or more of CU 110, DU 130, and RU 140 (each component is indicated by a dashed line to represent that each component may or may not be included in base station 102). Base station 102 provides an access point to core network 120 for UE 104. Base station 102 may include macro cells (high-power cellular base stations) and / or small cells (low-power cellular base stations). Small cells include femto cells, pico cells, and micro cells. A network including both small cells and macro cells may be referred to as a heterogeneous network. The heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may provide services to a restricted group called a closed subscriber group (CSG). The communication link between RU 140 and UE 104 may include an uplink (UL) (also referred to as a reverse link) transmission from UE 104 to RU 140 and / or a downlink (DL) (also referred to as a forward link) transmission from RU 140 to UE 104. The communication link may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link may pass through one or more carriers. For each carrier allocated in carrier aggregation with a total of up to Yx MHz (x component carriers) for transmission in each direction, base station 102 / UE 104 may use a spectrum with a bandwidth of up to Y MHz (e.g., 5 MHz, 10 MHz, 15 MHz, 20 MHz, 100 MHz, 400 MHz, etc.). These carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL compared to UL). Component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell) and the secondary component carriers may be referred to as secondary cells (SCells).

[0048] Some UEs 104 may use device-to-device (D2D) communication link 158 to communicate with each other. D2D communication link 158 may use DL / UL wireless wide area network (WWAN) spectrum. D2D communication link 158 may use one or more sidelink channels, such as physical sidelink broadcast channel (PSBCH), physical sidelink discovery channel (PSDCH), physical sidelink shared channel (PSSCH), and physical sidelink control channel (PSCCH). D2D communication may be carried out through various wireless D2D communication systems, such as for example Bluetooth TM (Bluetooth is a trademark of the Bluetooth Special Interest Group (SIG)), Wi-Fi based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard TM (Wi-Fi is a trademark of the Wi-Fi Alliance), LTE, or NR.

[0049] The wireless communication system may also include Wi-Fi TM AP 150, and this Wi-Fi TM AP communicates with the UE 104 (also known as a Wi-Fi TM Station (STA)) via a communication link 154, for example, in the 5 GHz unlicensed spectrum, etc. When communicating in the unlicensed spectrum, the UE 104 / AP 150 may perform a Clear Channel Assessment (CCA) before communication to determine whether the channel is available.

[0050] The electromagnetic spectrum is generally subdivided into various categories, frequency bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating frequency bands have been identified as Frequency Range Designation FR1 (410 MHz - 7.125 GHz) and FR2 (24.25 GHz - 52.6 GHz). Although a part of FR1 is greater than 6 GHz, in various documents and articles, FR1 is generally (interchangeably) referred to as the "sub-6 GHz" band. Regarding FR2, a similar naming issue sometimes occurs, and it is generally (interchangeably) referred to as the "millimeter wave" band in documents and articles, although it is different from the Extremely High Frequency (EHF) band (30 GHz - 300 GHz) identified as the "millimeter wave" band by the International Telecommunication Union (ITU).

[0051] The frequencies between FR1 and FR2 are generally referred to as mid-band frequencies. Recent 5G NR research has identified the operating frequency bands for these mid-band frequencies as Frequency Range Designation FR3 (7.125 GHz - 24.25 GHz). The frequency bands falling within FR3 may inherit the characteristics of FR1 and / or FR2, and thus can effectively extend the features of FR1 and / or FR2 to the mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operations beyond 52.6 GHz. For example, three higher operating frequency bands have been identified as Frequency Range Designation FR2-2 (52.6 GHz - 71 GHz), FR4 (71 GHz - 114.25 GHz), and FR5 (114.25 GHz - 300 GHz). Each of these higher frequency bands falls within the EHF band.

[0052] Considering the above aspects, unless otherwise specifically stated, if terms such as "sub-6 GHz" are used in this article, they can broadly represent frequencies that can be less than 6 GHz, can be within FR1, or can include mid-band frequencies. In addition, unless otherwise specifically stated, if terms such as "millimeter wave" are used in this article, they can be broadly represented as frequencies that can include mid-band frequencies, can be within FR2, FR4, FR2-2, and / or FR5, or can be within the EHF band.

[0053] Base station 102 and UE 104 may each include multiple antennas (such as antenna elements, antenna panels, and / or antenna arrays) to facilitate beamforming. Base station 102 may transmit beamformed signal 182 to UE 104 in one or more transmission directions. UE 104 may receive the beamformed signal from base station 102 in one or more reception directions. UE 104 may also transmit beamformed signal 184 to base station 102 in one or more transmission directions. Base station 102 may receive the beamformed signal from UE 104 in one or more reception directions. Base station 102 / UE 104 may perform beam training to determine the optimal reception and transmission directions for each of base station 102 / UE 104. The transmission and reception directions of base station 102 may be the same or may not be the same. The transmission and reception directions of UE 104 may be the same or may not be the same.

[0054] Base station 102 may include and / or be referred to as a gNB, Node B, eNB, access point, base station transceiver, radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), TRP, network node, network entity, network equipment, or some other suitable term. Base station 102 may be implemented as an integrated access and backhaul (IAB) node, a relay node, a sidelink node, an aggregated (monolithic) base station with a baseband unit (BBU) (including CU and DU) and an RU, or as a disaggregated base station including one or more of CU, DU, and / or RU. A set of base stations including disaggregated base stations and / or aggregated base stations may be referred to as a next generation (NG) RAN (NG-RAN).

[0055] The core network 120 may include an Access and Mobility Management Function (AMF) 161, a Session Management Function (SMF) 162, a User Plane Function (UPF) 163, a Unified Data Management (UDM) 164, one or more Location Servers 168, and other functional entities. The AMF 161 is a control node that processes signaling between the UE 104 and the core network 120. The AMF 161 supports registration management, connection management, mobility management, and other functions. The SMF 162 supports session management and other functions. The UPF 163 supports packet routing, packet forwarding, and other functions. The UDM 164 supports the generation of Authentication and Key Agreement (AKA) credentials, user identity handling, access authorization, and subscription management. One or more Location Servers 168 are illustrated as including a Gateway Mobile Location Center (GMLC) 165 and a Location Management Function (LMF) 166. However, in general, one or more Location Servers 168 may include one or more location / locationing servers, which may include one or more of the GMLC 165, LMF 166, a Position Determination Entity (PDE), a Serving Mobile Location Center (SMLC), a Mobile Positioning Center (MPC), etc. The GMLC 165 and LMF 166 support UE location services. The GMLC 165 provides an interface for clients / applications (e.g., emergency services) to access UE location information. The LMF 166 receives measurement and assistance information from the NG-RAN and the UE 104 via the AMF 161 to calculate the location of the UE 104. The NG-RAN may utilize one or more positioning methods to determine the location of the UE 104. Positioning the UE 104 may involve signal measurements, location estimation, and optional speed calculations based on these measurements. The signal measurements may be performed by the UE 104 and / or the base station 102 serving the UE 104. The measured signals may be based on a Satellite Positioning System (SPS) 170 (e.g., a Global Navigation Satellite System (GNSS), a Global Positioning System (GPS), a Non-Terrestrial Network (NTN), or one or more of other satellite positioning / location systems), an LTE signal, a Wireless Local Area Network (WLAN) signal, a Bluetooth signal, a Terrestrial Beacon System (TBS), sensor-based information (e.g., an atmospheric pressure sensor, a motion sensor), an NR Enhanced Cell ID (NR E-CID) method, an NR signal (e.g., multi-round-trip time (multi-RTT), DL Angle of Departure (DL-AoD), DL Time Difference of Arrival (DL-TDOA), UL Time Difference of Arrival (UL-TDOA), and UL Angle of Arrival (UL-AoA) positioning), and / or one or more of other systems / signals / sensors.

[0056] Examples of the UE 104 include cellular phones, smart phones, Session Initiation Protocol (SIP) phones, laptop computers, personal digital assistants (PDAs), satellite radios, global positioning systems, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablet computers, smart devices, wearable devices, vehicles, electricity meters, air pumps, large or small kitchen appliances, healthcare devices, implants, sensors / actuators, displays, or any other device with similar functionality. Some of the UEs in the UE 104 may be referred to as IoT devices (e.g., parking meters, air pumps, toasters, vehicles, heart monitors, etc.). The UE 104 may also be referred to as a station, mobile station, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, cell phone, user agent, mobile client, client, or some other suitable term. In some scenarios, the term UE may also apply to one or more companion devices, such as in a device constellation arrangement. One or more of these devices may access the network jointly and / or access the network individually.

[0057] Referring again to Figure 1 , in some aspects, the UE 104 may be configured to include a PDU set component 198, which is configured to: transmit a part of the uplink PDU set to the source cell; provide PDU set information for the uplink PDU set to the target cell to which the UE is handing over from the source cell; and transmit the remaining part of the uplink PDU set to the target cell after the handover to the target cell, for example as described in various aspects of the present disclosure. In some aspects, for example, when the base station is the target cell in the handover, the base station 102 may include a PDU set component 199, which is configured to: receive a handover message for the UE 104 from the source cell; receive buffered data for one or more PDU sets in transition between the source cell and the UE 104; receive PDU set information for one or more PDU sets; and communicate with the UE 104 based on the PDU set information for one or more PDU sets. The PDU set component 199 may be configured to: transmit or receive a part of the PDU set with the UE, for example when the base station 102 is the source cell in the handover. The apparatus initiates the handover of the UE to the target cell, provides the buffered data for the PDU set to the target cell, and provides the PDU set information for the PDU set to the target cell. Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar fields, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0058] Figure 2A FIG. 200 is an illustration example of a first subframe within a 5G NR frame structure. Figure 2B FIG. 230 is an illustration example of a DL channel within a 5G NR subframe. Figure 2C FIG. 250 is an illustration example of a second subframe within a 5G NR frame structure. Figure 2D FIG. 280 is an illustration example of a UL channel within a 5G NR subframe. The 5G NR frame structure can be frequency division duplex (FDD) (wherein for a specific set of subcarriers (carrier system bandwidth), the subframes within that set of subcarriers are dedicated to either DL or UL), or can be time division duplex (TDD) (wherein for a specific set of subcarriers (carrier system bandwidth), the subframes within that set of subcarriers are dedicated to both DL and UL). In Figure 2A 、 Figure 2C the examples provided, the 5G NR frame structure is assumed to be TDD, where subframe 4 is configured with slot format 28 (where most are DL), where D is DL, U is UL, and F is flexibly usable between DL / UL, and subframe 3 is configured with slot format 1 (where all are UL). Although subframes 3, 4 are shown as having slot formats 1, 28 respectively, any particular subframe can be configured with any of the various available slot formats 0 - 61. Slot formats 0, 1 are all - DL, all - UL respectively. The other slot formats 2 - 61 include a mixture of DL, UL, and flexible symbols. The UE is configured with the slot format by the received slot format indicator (SFI) (configured dynamically by DL control information (DCI) or semi - statically / statically by radio resource control (RRC) signaling). Note that the following description also applies to the 5G NR frame structure as TDD.

[0059] Figures 2A to 2DA frame structure is illustrated, and aspects of the present disclosure may be applicable to other wireless communication technologies that may have different frame structures and / or different channels. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms). Each subframe may include one or more time slots. The subframe may also include mini time slots, which may include 7, 4, or 2 symbols. Each time slot may include 14 or 12 symbols, depending on whether the cyclic prefix (CP) is normal or extended. For normal CP, each time slot may include 14 symbols, and for extended CP, each time slot may include 12 symbols. The symbols on the DL may be cyclic prefix orthogonal frequency division multiplexing (CP-OFDM) symbols. The symbols on the UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (for power-constrained scenarios; limited to single-stream transmission). The number of time slots within a subframe is based on the CP and the parameter set. The parameter set defines the subcarrier spacing (SCS) (see Table 1). The symbol length / duration may be scaled with 1 / SCS.

[0060]

[0061] Table 1: Parameter Sets, SCS, and CP

[0062] For normal CP (14 symbols / slot), different parameter sets μ0 to 4 allow 1, 2, 4, 8, and 16 time slots per subframe, respectively. For extended CP, parameter set 2 allows 4 time slots per subframe. Thus, for normal CP and parameter set μ, there are 14 symbols / slot and 2 μ time slots / subframe. The subcarrier spacing may be equal to 2 μ *15 kHz, where μ is parameter set 0 to 4. Thus, the subcarrier spacing for parameter set μ = 0 is 15 kHz, and the subcarrier spacing for parameter set μ = 4 is 240 kHz. The symbol length / duration is negatively correlated with the subcarrier spacing. Figures 2A to 2D An example is provided with normal CP having 14 symbols per time slot and parameter set μ = 2 having 4 time slots per subframe. The time slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs. Within a frame set, there may be one or more different bandwidth parts (BWPs) that are frequency division multiplexed (see Figure 2B ). Each BWP may have a specific parameter set and CP (normal or extended).

[0063] The resource grid can be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as a physical RB (PRB)) that extends over 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0064] As Figure 2A Illustrated, some of the REs in the RE carry reference (pilot) signals (RSs) for the UE. The RS may include a demodulation RS (DM-RS) (designated as R for a specific configuration, but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS) for channel estimation at the UE. The RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0065] Figure 2B Examples of various DL channels within a subframe of a frame are illustrated. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs) (e.g., 1, 2, 4, 8, or 16 CCEs), each CCE including six resource element groups (REGs), each REG including 12 consecutive REs in the OFDM symbols of an RB. The PDCCH within a BWP can be referred to as a control resource set (CORESET). The UE is configured to monitor PDCCH candidates in a PDCCH search space (e.g., a common search space, a UE-specific search space) during a PDCCH monitoring occasion on the CORESET, where the PDCCH candidates have different DCI formats and different aggregation levels. Additional BWPs may be located at higher and / or lower frequencies on the channel bandwidth. The primary synchronization signal (PSS) can be in symbol 2 of a specific subframe of the frame. The PSS is used by the UE 104 to determine subframe / symbol timing and the physical layer identity. The secondary synchronization signal (SSS) can be in symbol 4 of a specific subframe of the frame. The SSS is used by the UE to determine the physical layer cell identity group number and the radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine the physical cell identifier (PCI). Based on this PCI, the UE can determine the location of the DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) can be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block (also referred to as an SS block (SSB)). The MIB provides the system frame number (SFN) and the number of RBs in the system bandwidth. The physical downlink shared channel (PDSCH) carries user data, broadcast system information (such as system information blocks (SIBs)) not sent via the PBCH, and paging messages.

[0066] As Figure 2CAs illustrated, some of the REs in the RE carry DM-RS (indicated as R for a specific configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may transmit the DM-RS of the physical uplink control channel (PUCCH) and the DM-RS of the physical uplink shared channel (PUSCH). The PUSCH DM-RS may be transmitted in the previous one or two symbols of the PUSCH. Depending on whether a short PUCCH or a long PUCCH is transmitted and depending on the specific PUCCH format used, the PUCCH DM-RS may be transmitted in different configurations. The UE may transmit a sounding reference signal (SRS). The SRS may be transmitted in the last symbol of the subframe. The SRS may have a comb structure, and the UE may transmit the SRS on one of the teeth of the comb. The SRS may be used by the base station for channel quality estimation to enable frequency-dependent scheduling of the UL.

[0067] Figure 2D Examples of various UL channels within a subframe of a frame are illustrated. The PUCCH may be located at the position indicated in one configuration. The PUCCH carries uplink control information (UCI), such as a scheduling request, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and a hybrid automatic repeat request (HARQ) acknowledgement (ACK) (HARQ-ACK) feedback (i.e., one or more HARQ ACK bits indicating one or more ACKs and / or negative ACKs (NACKs)). The PUSCH carries data and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0068] Figure 3It is a block diagram of the communication between the base station 310 and the UE 350 in the access network. In the DL, Internet Protocol (IP) packets can be provided to the controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes the Radio Resource Control (RRC) layer, and layer 2 includes the Service Data Adaptation Protocol (SDAP) layer, the Packet Data Convergence Protocol (PDCP) layer, the Radio Link Control (RLC) layer, and the Medium Access Control (MAC) layer. The controller / processor 375 provides RRC layer functionality associated with the broadcast of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs), error correction via ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and re-ordering of RLC data PDUs; and MAC layer functionality associated with the mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via HARQ, priority handling, and logical channel prioritization.

[0069] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1, which includes the physical (PHY) layer, may include error detection on the transport channel, forward error correction (FEC) encoding / decoding of the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 handles the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase phase shift keying (M-PSK), M-order quadrature amplitude modulation (M-QAM)). The encoded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to OFDM subcarriers, multiplexed with reference signals (e.g., pilots) in the time and / or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying a stream of time-domain OFDM symbols. The OFDM stream is precoded in space to generate multiple spatial streams. Channel estimates from the channel estimator 374 may be used to determine the encoding and modulation schemes, as well as for spatial processing. The channel estimates may be derived from reference signals transmitted by the UE 350 and / or channel condition feedback. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318Tx. Each transmitter 318Tx may modulate a radio frequency (RF) carrier using the corresponding spatial stream for transmission.

[0070] At the UE 350, each receiver 354Rx receives signals via its corresponding antenna 352. Each receiver 354Rx recovers the information modulated onto the RF carrier and provides the information to the receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they may be combined by the RX processor 356 into a single OFDM symbol stream. The RX processor 356 then uses a fast Fourier transform (FFT) to convert the OFDM symbol stream from the time domain to the frequency domain. The frequency-domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, as well as the reference signals, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 310. These soft decisions may be based on the channel estimates computed by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted by the base station 310 on the physical channel. The data and control signals are then provided to the controller / processor 359, which implements layer 3 and layer 2 functionality.

[0071] The controller / processor 359 (or processor circuitry) may be associated with at least one memory 360 (or memory circuitry) that stores program code and data. The at least one memory 360 may be referred to as a computer-readable medium. In the UL, the controller / processor 359 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets. The controller / processor 359 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0072] Similar to the functionality described in connection with DL transmission performed by the base station 310, the controller / processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with transfer of upper layer PDUs, error correction via ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and re-ordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via HARQ, priority handling, and logical channel prioritization.

[0073] Channel estimates derived by the channel estimator 358 based on reference signals or feedback transmitted by the base station 310 may be used by the TX processor 368 to select appropriate decoding and modulation schemes and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via a separate transmitter 354Tx. Each transmitter 354Tx may modulate an RF carrier with a respective spatial stream for transmission.

[0074] UL transmission is processed at the base station 310 in a manner similar to that described in connection with the receiver functionality at the UE 350. Each receiver 318Rx receives signals via its respective antenna 320. Each receiver 318Rx recovers the information modulated onto the RF carrier and provides the information to the RX processor 370.

[0075] The controller / processor 375 (or processor circuitry) may be associated with at least one memory 376 (or memory circuitry) that stores program code and data. The at least one memory 376 may be referred to as a computer-readable medium. In the UL, the controller / processor 375 provides demultiplexing between transmission channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets. The controller / processor 375 is also responsible for error detection using the ACK and / or NACK protocols to support HARQ operations.

[0076] At least one of the TX processor 368, RX processor 356, and controller / processor 359 may be configured to perform aspects of the PDU set component 198 in connection with Figure 1 the PDU set component 198.

[0077] At least one of the TX processor 316, RX processor 370, and controller / processor 375 may be configured to perform aspects of the PDU set component 199 in connection with Figure 1 the PDU set component 199.

[0078] A wireless communication system may support various types of wireless services. Different wireless services may be associated with different latencies, reliabilities, quality of service (QoS), etc. An example of one type of wireless service is an extended reality (XR) service.

[0079] Figure 4 FIG. 400 is a diagram illustrating an example XR service. The XR service may refer to wireless communication for technologies such as virtual reality (VR), mixed reality (MR), and / or augmented reality (AR). VR may refer to a technology in which a user is immersed in a simulated experience that is similar to or different from the real world. The user may interact with a VR system through a VR headset or a multi-projection environment that generates realistic images, sounds, and other sensations that simulate the user's physical presence in a virtual environment. MR may refer to a technology in which aspects of a virtual environment and the real environment are combined. AR may refer to a technology in which objects residing in the real world are enhanced via computer-generated perceptual information, sometimes across multiple sensory modalities such as vision, hearing, touch, somatosensation, and / or smell. An AR system may combine a combination of the real world and the virtual world, real-time interaction, and accurate three-dimensional registration of virtual and real objects. In one example, an AR system may overlay sensory information (e.g., images) onto a natural environment and / or mask real objects from a natural environment. The XR service may include video data and / or audio data. The XR service may be sent by a base station and received by a UE, or the XR service may be sent by a UE and received by a base station.

[0080] XR traffic can arrive in periodic traffic bursts (“XR traffic bursts”). XR traffic bursts can vary in the number of packets per burst and / or the size of each packet in the burst. Diagram 400 illustrates a first XR stream 402 that includes a first XR traffic burst 404 and a second XR traffic burst 406. As illustrated in Diagram 400, traffic bursts can include different numbers of packets. For example, the first XR traffic burst 404 is shown as having three packets (represented as rectangles in Diagram 400), and the second XR traffic burst 406 is shown as having two packets. Additionally, as illustrated in Diagram 400, the three packets in the first XR traffic burst 404 and the two packets in the second XR traffic burst 406 can vary in size, that is, the packets within the first XR traffic burst 404 and the second XR traffic burst 406 can include different amounts of data.

[0081] XR traffic bursts can arrive at non-integer periods (i.e., in non-integer cycles). These periods can be different from an integer number of symbols, time slots, etc. In one example, for 60 frames per second (FPS) video data, XR traffic bursts can arrive at a period of 1 / 60 = 16.67 ms. In another example, for 120 FPS video data, XR traffic bursts can arrive at a period of 1 / 120 = 8.33 ms.

[0082] The arrival time of XR traffic can vary. For example, an XR traffic burst can arrive at a time earlier or later than the time when the UE (or base station) expects the XR traffic burst and can be used for transmission. The variability of packet arrival relative to a period (e.g., a 16.76 ms period, an 8.33 ms period, etc.) can be referred to as “jitter”. In one example, the jitter of XR traffic can be in the range of -4 ms (earlier than expected arrival) to +4 ms (later than expected arrival). For example, referring to the first XR stream 402, the UE can expect the first packet of the first XR traffic burst 404 to arrive at time t0, but the first packet of the first XR traffic burst 404 arrives at time t1.

[0083] XR traffic can include multiple streams that arrive at the UE (or base station) concurrently (or within a threshold time period). For example, Diagram 400 includes a second XR stream 408. The second XR stream 408 can have different characteristics from the first XR stream 402. For example, the second XR stream 408 can have XR traffic bursts that have different numbers of packets, packets of different sizes, etc. In one example, the first XR stream 402 can include video data, and the second XR stream 408 can include audio data for the video data. In another example, the first XR stream 402 can include intracoded picture frames (I-frames) that contain complete images, and the second XR stream 408 can include predicted picture frames (P-frames) that contain changes from a previous image.

[0084] The XR service may have an associated packet delay budget (PDB). If a packet does not arrive within the PDB, the UE (or the base station) may discard the packet. In one example, if the packets corresponding to the video frames of a video do not arrive at the UE within the PDB, the UE may discard the packets because the video has advanced beyond that frame.

[0085] Generally speaking, the XR service is characterized by relatively high data rates and low latency. The latency in the XR service can affect the user experience. For example, the XR service may have applications in eMBB and URLLC services.

[0086] Some applications may generate multiple types of uplink data streams. Different streams may have different timing deadlines. For example, different data streams of the same application may have different packet delay budgets. A non-limiting example of such an application is an extended reality (XR) application (e.g., or similarly, a virtual reality (VR) application or an augmented reality application) or different types of cloud-based game applications. In the XR example, the XR application may generate pose or control packets of information that may have a packet delay budget of 4 ms, and the pose or control packets of the information may arrive for transmission (e.g., generation) at a period of 10 ms. Such pose data may be based on the movement of the user's head, the user's field of view, etc. For example, the application may sample the head position every 10 ms and generate updates to be sent to the other end of the application (such as a cloud-based server). The XR application may also generate hand gesture tracking information to track the movement of the player's hand, and the hand gesture tracking information may have a longer packet delay budget of 10 ms and may arrive for transmission every 40 ms (e.g., at a period of 40 ms). The XR application may generate voice or audio for transmission, and the voice or audio may have a longer delay budget of 15 ms and may arrive for transmission at a period of 20 ms. In this example, the XR application may generate different traffic streams that may have different packet delay budgets and different generation periods.

[0087] The reliability of wireless communication such as the data exchanged for XR applications affects the user experience. For example, the loss of a PDU or the interruption of a set of PDUs may cause an interruption or delay in the XR experience, which may affect the user's satisfaction with the XR application. As an example, the video of an XR application may have a periodic pattern, such as where video frames are transmitted or received within each period. The loss of a set of PDUs with video frame data may cause an interruption in the video of the XR application, which may reduce the quality of the XR user experience.

[0088] A PDU set is a collection or group of PDUs delivered as an integrated unit between the RAN and the applications at the UE. For example, the PDUs in a PDU set share common QoS attributes such as the PDU set delay budget (PSDB), the PDU set error rate (PSER), and other examples of QoS attributes that can be common to the PDUs in the PDU set. An example of a PDU set is data for a video frame or a slice within a video frame.

[0089] Figure 5 Various examples of PDU sets are illustrated. As Figure 5 illustrated, a PDU set can have different sizes, e.g., a different number or sequence of PDUs. Figure 5 It is illustrated that each PDU in a PDU set can include header information identifying the PDU set (e.g., using a PDU set identifier (ID)) and the sequence number of the PDU within the set. For example, for PDU set #1 (e.g., 508), the PDU set includes 6 PDUs. The header of the sixth PDU can indicate PDU set #1 and sequence number 6, such that the recipient of the PDU (or feedback for the PDU) will be able to identify the PDU as the 6th PDU in PDU set #1. Figure 5 It is also shown a PDU set #2 (e.g., 510) with 4 PDUs. The header of the fourth PDU can indicate the PDU set ID of PDU set #2 and the sequence number 4. Figure 5 It is also shown a PDU set #3 (e.g., 512) with 3 PDUs. The header of the second PDU can indicate the PDU set ID of PDU set #3 and the sequence number 2. The sequence number carries the meaning of the order within the corresponding PDU set and does not uniquely identify a PDU outside the PDU set. Figure 5 It is illustrated that one or more PDUs within a PDU set may not be accurately received by the recipient, e.g., which may be referred to as lost in this document.

[0090] Different PDU sets can have different types of decoding criteria, which can be referred to as PDU set content criteria. In some aspects, for different applications, e.g., based on the specific implementation of an individual application, the decoding criteria can be different.

[0091] As a first example of the decoding criteria (or PDU set content criteria), if any PDU in a PDU set is lost (e.g., not accurately received at the recipient), then the entire PDU set may become obsolete. The first example can be referred to as an "all or nothing" decoding criterion or content criterion. For the all or nothing example, the PDU sets Figure 5 #2 and PDU set #3 can be discarded because one of the PDUs was not accurately received.

[0092] As a second example of a decoding criterion (or PDU set content criterion), the received PDU in the PDU set may be considered good (e.g., usable by the application) until the occurrence of the first PDU loss (e.g., until the first PDU in the PDU set is lost or not received by the receiver). The second example may be referred to as the "good until the first loss" decoding criterion or content criterion. For the good until the first loss example, the first two PDUs in PDU set #2 and PDU set #3 may be considered good because they are received before the lost / missed PDU in the PDU set. The fourth PDU in PDU set #2 may be discarded because it follows the lost / missed PDU in the sequence within the PDU set.

[0093] As a third example of a decoding criterion (or PDU set content criterion), the PDUs in the PDU set may be encoded using application layer forward error correction (AL-FEC), and based on the FEC redundancy ratio, the PDUs in the PDU set may be decoded when a subset of the PDUs is lost or not received. The application that is the source of the PDU set may add redundancy to the original data. As an example for illustrating this concept, for 10 data packets, redundant data of 5 packet sizes may be added to form a total of 15 packets. If the UE receives a subset of the 15 packets (e.g., such as 11 packets), the UE may still be able to obtain the original 10 data packets based on the introduced redundancy. In this example, the use of AL-FEC may enable decoding of the PDU set based on a subset of the PDUs in the PDU set. The third example may be referred to as the AL-FEC decoding criterion or content criterion. As an example, in Figure 5 based on the redundancy provided by AL-FEC, the data from PDU set #3 may be able to be decoded using the first PDU and the second PDU even if the third PDU is not received accurately.

[0094] PDUs can be discarded by the UE and / or by the RAN based on a latency budget and / or a loss criterion. For example, if the remaining latency budget (RDB) expires or if another timer associated with the PDU expires, the PDU can be discarded. For example, if an associated layer 2 (L2) timer such as a PDCP discard timer, an RLC reordering timer, an RLC discard timer, or a PDCP reordering timer expires, the PDU can be discarded. PDUs can be discarded, for example, by the network or the UE based on a decoding criterion or a content criterion for an associated PDU set. For example, if the decoding criterion / content criterion for a PDU set can no longer be met or has been met, the UE or the network can discard the associated PDUs (e.g., discard for transmission or reception / decoding). In some aspects, if PDU loss occurs for a PDU set with an "all-or-nothing" content criterion, the PDUs in the PDU set can be discarded. In other aspects, if a threshold number of PDUs within an AL-FEC PDU set have been received (such that the data can be decoded from a subset of the PDUs), subsequent PDUs can be discarded (e.g., not received or transmitted).

[0095] There are dependencies between PDUs in a PDU set. When handling a PDU set, e.g., as part of transmitting, receiving, or decoding PDUs in the PDU set, the UE and the RAN can maintain PDU set state information. By maintaining the PDU set state information, the sender or the receiver can determine when the content criterion that causes the PDUs in the PDU set to be discarded is met, e.g., the content criterion is based on PDU loss or AL-FEC decoding using a subset of the PDUs.

[0096] Some events can cause a change in the connection between the network and the UE. As an example, the UE can be mobile within the network and can experience a mobility event in which the UE changes to a different cell or has a reconfiguration of the RRC configuration with a synchronization event with the network. For example, the network can perform a handover to transfer the UE from being served by a source cell to being served by a target cell. In some aspects, a cell such as the primary-secondary cell (PSCell) for the UE can change. As another example, the network can provide an RRC reconfiguration or an RRC re-establishment to the UE. In conjunction with a mobility event, the source base station can forward data stored in a buffer for the UE to the target base station for the UE. Forwarding of buffered data can help avoid data loss when a mobility event occurs. In some aspects, a tunnel can be established between the source base station (or source cell) and the target base station (or target cell), and the source base station can forward the buffered data to the target base station through the tunnel, which can occur without additional user plane procedures.

[0097] Aspects presented herein enable a target cell in a handover of a UE to obtain PDU set information for an in - progress set of PDUs (e.g., a set of PDUs in transition) between a source cell and the UE. For data provided as a PDU set, such as for XR services, if the data buffered at the source cell is associated with a PDU set in which PDUs have not been fully sent or received, providing the information for the PDU set to the target cell enables the target cell to appropriately handle the PDU set. As an example, if PDU n in the PDU set (e.g., numbered n in the sequence of the PDU set) has been successfully transmitted by the source cell, the lowest sequence number of the PDUs forwarded to the target cell is PDU n + 1. In the absence of PDU set information, the target cell does not know whether the lower - numbered PDUs in the PDU set sequence have been successfully sent, successfully received, or lost.

[0098] Aspects presented herein, for example, improve the reliability of communication with the network and help avoid discarding a PDU set when a handover occurs. The increased reliability improves the user experience. As an example, the reliability of sending and receiving PDUs for XR wireless communication can have a significant impact on the XR user experience, which can be improved by aspects of the present disclosure. For example, the loss of a PDU or the interruption of a PDU set can cause an interruption or delay in the XR experience, which can affect the user's satisfaction with the XR application. As presented herein, the target cell can receive buffered PDUs from the source cell and can use the PDU set information (e.g., implementing the maintenance of PDU set status information) to continue communication with the UE for the PDU set, including the application of decoding criteria or content criteria for the PDU set.

[0099] Figure 6 Illustrated is a communication flow 600 related to a handover or mobility event of UE 602 for a downlink PDU set between UE 602, source cell 604, and target cell 606. Aspects performed by the source cell can be performed by a network node such as a base station or one or more components of a base station (such as a CU, DU, and / or RU). Aspects performed by the target cell can be performed by a network node such as a base station or one or more components of a base station (such as a CU, DU, and / or RU).

[0100] UE 602 exchanges downlink and / or uplink communication 608 with the source cell 604. As shown at 612, the source cell begins to send PDUs in a downlink PDU set to UE 602. UE 602 begins receiving PDUs in the PDU set at 612 and maintains PDU set state information at 610. The UE may know the size of the PDU set (e.g., the number of PDUs in the PDU set) and the identifier of the PDU set (e.g., PDU set ID). Additionally, the header of each PDU in the PDU set may include the PDU set ID and a sequence number for indicating the position of the PDU within the PDU set in order, such as described in conjunction with Figure 5 as described. The UE may use decoding criteria / content criteria for the PDU set to determine whether to discard one or more PDUs in the PDU set.

[0101] UE 602 may provide feedback 614 (e.g., ACK / NACK feedback) to the source cell 604. At 616, the source cell 604 may maintain PDU set state information. The state information for the PDU set may be based on the PDUs that have been sent within the PDU set and may be based on feedback 614 from UE 602 indicating the PDUs within the PDU set that have been accurately received by the UE. The source cell may use the state information to determine whether to discard (e.g., and not send) one or more PDUs in the PDU set. For example, if the UE fails to receive a PDU for a PDU set with an all-or-nothing content criterion or a good-until-first-loss content criterion, the source cell may discard the remaining PDUs and not send them. As another example, if the UE has received a subset of PDUs with AL-FEC that has enabled the UE to successfully decode the data based on redundancy, the source cell may discard the remaining PDUs instead of sending them. When a handover event occurs for the UE, a downlink PDU set may be partially sent. For example, the source cell may have sent a subset of the PDUs in the PDU set and may have remaining PDUs in the PDU set to be sent. In some aspects, the PDU set for which transmission begins at 612 may be referred to as "in transition," meaning that the transmission of the PDUs in the PDU set has begun and there are remaining PDUs to be sent.

[0102] Figure 6A handover is shown as an example of a mobility event. The source cell 604 may initiate a handover to the target cell 606 and may exchange one or more handover messages with the target cell 606. During the mobility event, when the source cell 604 forwards buffered downlink data in a data radio bearer (DRB) associated with a PDU set (e.g., including PDUs of a PDU set in transition), the source cell 604 provides PDU set information for the PDU set to the target cell, as shown in the handover message 618 from the source cell 604 to the target cell 606. In some aspects, the PDU set information may be provided in the same message as the buffered data (e.g., the remaining PDUs in the PDU set). In other aspects, the PDU set information may be provided in a message separate from the buffered data.

[0103] As part of the PDU set information, before the start of data forwarding from the source cell to the target cell (e.g., for each PDU set in transition), the source cell 604 may provide a PDU set identifier for each PDU set in which some PDUs of its PDU have been transmitted or discarded. There may be one or more PDU sets in transition when the handover occurs. For each PDU set in transition, when data forwarding begins, the source cell 604 may provide in-sequence information within the PDU set to the target cell 606, such as the sequence number of the last transmitted PDU, the last discarded PDU, or the next expected PDU. The in-sequence number within the PDU set corresponds to the sequence number of the PDUs within the PDU set. This in-sequence number within the PDU set is unique within the PDU set and not unique across different PDU sets.

[0104] In some aspects, the source cell 604 may provide the size of each PDU set in transition as part of the PDU set information. The size may be signaled as the number of PDUs within the PDU set, the number of bytes of the PDU set, or another indication of the size. In other aspects, the size of the PDU set may be signaled in each header of the PDUs, as may be received by the target cell from the header rather than from the source cell. In some aspects, the source cell 604 may provide content criteria for each PDU set in transition as part of the PDU set information. In other aspects, the content criteria may be configured via control plane signaling or signaled in the PDU header rather than provided in the message from the source cell 604 to the target cell 606.

[0105] Then, target cell 606 can use the buffered data and PDU set information to continue to handle the downlink transmission of the remaining PDUs in PDU set 622 that were in transition when the handover occurred. Target cell 606 can transmit one or more remaining PDUs and maintain PDU set status information at 620 such that the target cell can handle the PDU set according to decoding / content criteria. Target cell 606 can receive feedback 624 from UE 602. This feedback can identify the corresponding PDU set ID and the sequence numbers within the PDU set. Since the target cell has the PDU set information from the source cell, the target cell can use the feedback to determine if there are PDUs within the PDU set that have not been accurately received by the UE and / or if the UE has received a threshold number of PDUs in the AL-FEC-based PDU set. Target cell 606 can continue to transmit the PDUs in the PDU set or can discard PDUs according to the content criteria for the PDU set and the status information for the PDU set (based on the received PDU set information), similar to the handling described at 616. Since the target cell has the PDU set information for the PDU set at 618, when the target cell receives feedback from the UE at 624, the target cell can consider the feedback in conjunction with the received PDU set information. If the target cell receives PDU set information indicating that the last PDU sent before the handover was PDU#n (or the next expected PDU is PDU#n+1), then if the target cell receives feedback for PDU#n, the target cell can determine that no PDUs in the PDU set have been lost and can continue to transmit the remaining PDUs.

[0106] The handover between source cell 604 and target cell 606 can be, for example, an Xn handover. For example, the PDU set information provided at 618 can be included in an Xn handover request message, an Xn PDCP status transfer message, or an early status transfer message.

[0107] In other aspects, the handover can be an NG handover. Figure 7 Communication flow 700 for a downlink PDU set in transition when an NG handover occurs is illustrated between UE 702, source cell 704, target cell 706, and AMF 708. Aspects performed by the source cell can be performed by a network node such as a base station or one or more components of a base station (such as a CU, DU, and / or RU). Aspects performed by the target cell can be performed by a network node such as a base station or one or more components of a base station (such as a CU, DU, and / or RU).

[0108] Although Figure 7Although not illustrated, the UE 702 and the source cell 704 may exchange downlink and / or uplink communications before handover. As shown at 712, the source cell 704 begins to send PDUs in a downlink PDU set to the UE 702, and the UE provides feedback 714, which may include any of the aspects described for 612 and 614. At 710, the UE maintains PDU set state information, and at 716, the source cell maintains PDU set state information, such as described in conjunction with Figure 6 610 and 616 in

[0109] The source cell 704 initiates a handover to the target cell 706 by providing a handover message to the AMF 708. The AMF 708 provides one or more handover messages to the target cell 706. At 718, the source cell 704 may provide buffered data and PDU set information to the AMF as described in conjunction with 618. At 719, the AMF 708 may provide buffered data and PDU set information to the target cell. The PDU set information may be included in an NG handover required message from the source cell 704 to the AMF 708, or may be included in an NG AP handover request message. At 720, the target cell 706 may use the PDU set information received at 719 to maintain PDU set state information and to handle the remaining PDUs in the PDU set that are in transition when the handover occurs, as shown at 722. At 724, the UE may provide feedback, which the target cell interprets in view of the received PDU set information for the PDU set.

[0110] Figure 8 A communication flow 800 related to a handover or mobility event of the UE 802, such as an Xn handover, for an uplink PDU set between the UE 802, the source cell 804, and the target cell 806 is illustrated. Aspects performed by the source cell may be performed by a network node such as a base station or one or more components of a base station (such as a CU, a DU, and / or an RU). Aspects performed by the target cell may be performed by a network node such as a base station or one or more components of a base station (such as a CU, a DU, and / or an RU).

[0111] The UE 802 and the source cell 804 may exchange downlink and / or uplink communications before handover, such as Figure 6is illustrated at 608. As shown at 812, UE 802 begins to send PDUs in an uplink PDU set to source cell 804. At 810, UE 802 maintains PDU set state information. The UE can use decoding / content criteria for the PDU set to determine whether to discard one or more PDUs in the PDU set. For example, if feedback 814 indicates that source cell 804 fails to receive PDUs for a PDU set with an all-or-nothing content criterion or a good-until-first-loss content criterion, then UE 802 can discard the remaining PDUs and not send them. As another example, if feedback 814 indicates or the UE otherwise determines that source cell 804 has received a subset of PDUs with AL-FEC that has enabled successful decoding of the data based on redundancy, then UE 802 can discard the remaining PDUs instead of sending them. Source cell 804 can similarly maintain PDU set state information, for example at 816, and use this information to determine whether to discard PDUs or continue to attempt to decode the PDUs. When a handover event occurs for UE 802, an uplink PDU set can be partially sent, such as described in conjunction with Figure 6 the downlink PDU set in

[0112] Source cell 804 can initiate a handover to target cell 806 and can exchange one or more handover messages with target cell 806. Source cell 804 can forward buffered data to target cell 806, for example as shown at 818. Similar to Figure 6 the example in

[0113] For example, during a mobility event, after the source cell 804 receives an acknowledgment of a request for a synchronized RRC reconfiguration from the target cell 806 for the source cell pair, for each DRB associated with a PDU set, the source cell 804 may provide appropriate PDU set information to the target cell 806 at 818. Similar to the information provided at 618, as part of the status information, at 818, for a PDU set, before the start of data forwarding from the source cell to the target cell (e.g., for each uplink PDU set in transition), the source cell 804 may provide the PDU set identifier of each PDU set in the PDU set for which some PDUs in its PDU have been received or discarded. There may be one or more PDU sets in transition when the handover occurs. For each PDU set in transition, when data forwarding starts, the source cell 804 may provide in-sequence information within the PDU set to the target cell 606, such as the sequence number of the next expected PDU that the source cell 804 expects to receive. The sequence number within the PDU set corresponds to the sequence number of the PDUs within the PDU set.

[0114] In some aspects, the source cell 804 may provide the size of each uplink PDU set in transition as part of the PDU set information for the PDU set. The size may be signaled as the number of PDUs within the PDU set, the number of bytes of the PDU set, or another indication of the size. In other aspects, the size of the PDU set may be signaled in each header of the PDUs, as may be received by the target cell from the header rather than from the source cell. In some aspects, the source cell 804 may provide content criteria for each uplink PDU set in transition as part of the PDU set information for the PDU set. In other aspects, the content criteria may be configured via control plane signaling or signaled in the PDU header rather than provided in a message from the source cell 804 to the target cell 806.

[0115] Then, the target cell 806 may use the buffered data and the PDU set information to continue handling the reception of the remaining uplink PDUs in the PDU set 822 in transition when the handover occurs. The target cell 806 may receive one or more remaining PDUs and maintain PDU set status information at 820 such that the target cell can handle the PDU set according to decoding criteria / content criteria. The target cell 806 may provide feedback 824 to the UE 802.

[0116] The handover between the source cell 804 and the target cell 806 may be, for example, an Xn handover. For example, the PDU set information provided at 818 may be included in an Xn handover request message, an Xn PDCP status transfer message, or an early status transfer message.

[0117] In some aspects, the handover can be, for example, an NG handover as described in conjunction with Figure 7 and instead of being provided directly from the source cell 804 to the target cell 806, the PDU set information shown at 818 can be provided by the source cell to the AMF, which in turn provides the PDU set information to the target cell.

[0118] In some aspects, the PDU set information for one or more uplink PDU sets can be provided by the UE to the target cell. Figure 9 Illustrates an example communication flow 900 between a UE 902, a source cell 904, and a target cell 906 corresponding to Figure 6 . Figure 9 Shows a similar aspect of handover and PDU transmission with the same reference numerals used as in Figure 8 . However, compared to Figure 8 , in Figure 9 , the handover message 918 from the source cell 904 provides buffered data instead of PDU set information. Instead, the UE 902 sends the PDU set information 919 to the target cell 906. The PDU set information 919 can include the information described in conjunction with 818, such as the PDU set ID and sequence information about the last transmitted PDU in the PDU set, the next PDU to be transmitted, or the next PDU to be received for the target cell 906.

[0119] During a mobility event, after the UE 902 completes the first RACH procedure in the target cell 906, the UE 902 can provide the PDU set information 919 to the target cell 906. The PDU set information 919 can be signaled to the target cell 906 in an RRC message, such as in UE assistance information included in the RRC message.

[0120] Figure 10 Is a flowchart 1000 of a method of wireless communication. The method can be performed at a base station or other network entity configured as a target cell (e.g., Figure 14 the base station 102, CU 110, DU 130, RU 140, base station 310, target cell 606, target cell 706, target cell 806, target cell 906, or network entity 1402 in the hardware implementation of

[0121] AsFigure 10 As shown, at 1002, a handover message for the UE is received from the source cell. For example, referring to Figure 6 , at 618, the target cell 606 may receive the handover message from the source cell 604. In another example, referring to Figure 7 , at 719, the target cell 706 may receive the handover message from the AMF 708, and the handover message is based on the handover message sent by the source cell 704 at 718. In another example, referring to Figure 8 , at 818, the target cell 806 may receive the handover message from the source cell 804. In yet another example, referring to Figure 9 , at 918, the target cell 906 may receive the handover message from the source cell 904. In some aspects, 1002 may be performed by the PDU session component 199.

[0122] At 1004, buffered data for the PDU session in transition between the source cell and the UE may be received. For example, referring to Figure 6 , at 618, the target cell 606 may receive the buffered data for the PDU session in transition between the source cell 604 and the UE 602. In another example, referring to Figure 7 , at 719, the target cell 706 may receive from the AMF 708 the buffered data for the PDU session in transition between the source cell 704 and the UE 702. The buffered data received at 719 is based on the buffered data sent by the source cell 704 to the AMF 708 at 718. In another example, referring to Figure 8 , at 818, the target cell 806 may receive the buffered data for the PDU session in transition between the source cell 804 and the UE 802. In another example, referring to Figure 9 , at 918, the target cell 906 may receive the buffered data for the PDU session in transition between the source cell 904 and the UE 902. In some aspects, 1004 may be performed by the PDU session component 199.

[0123] At 1006, PDU session information for the PDU session may be received. For example, referring to Figure 6 , at 618, the target cell 606 may receive the PDU session information for the PDU session. In another example, referring to Figure 7 , at 718, the target cell 706 may receive the PDU session information for the PDU session. In another example, referring to Figure 8 , at 818, the target cell 806 may receive the PDU session information for the PDU session. In yet another example, referring to Figure 9, at 918, the target cell 906 may receive PDU set information for a PDU set. In some aspects, 1006 may be performed by the PDU set component 199.

[0124] In some aspects, the PDU set information may be received from a source cell. For example, referring to Figure 6 , at 618, the target cell 606 may receive PDU set information from the source cell 604. In another example, referring to Figure 8 , at 818, the target cell 806 may receive PDU set information from the source cell 804.

[0125] In some aspects, the PDU set information may be received via the Xn interface between the target cell and the source cell. For example, referring to Figure 6 , the PDU set information received at 618 may be received by the target cell 606 via the Xn interface between the target cell 606 and the source cell 604. In another example, referring to Figure 8 , the PDU set information received at 818 may be received by the target cell 806 via the Xn interface between the target cell 806 and the source cell 804.

[0126] In some aspects, the PDU set information may be included in at least one of an Xn handover request message, an Xn PDCP status transfer message, or an early status transfer message. For example, referring to Figure 6 , the PDU set information received at 618 may be included in at least one of an Xn handover request message, an Xn PDCP status transfer message, or an early status transfer message. In another example, referring to Figure 8 , the PDU set information received at 818 may be included in at least one of an Xn handover request message, an Xn PDCP status transfer message, or an early status transfer message.

[0127] In some aspects, the buffered data may include one or more downlink PDU sets in which at least one PDU has been sent from the source cell to the UE and there is at least one remaining PDU to be sent to the UE. For example, referring to Figure 6 , the buffered data received by the target cell 606 at 618 may include one or more downlink PDU sets in which at least one PDU has been sent from the source cell 604 to the UE 602 and there is at least one remaining PDU to be sent to the UE 602. In another example, referring to Figure 7 , the buffered data received by the target cell 706 at 719 may include one or more downlink PDU sets in which at least one PDU has been sent from the source cell 704 to the UE702 and there is at least one remaining PDU to be sent to the UE 702.

[0128] In some aspects, the PDU set information for a PDU set may include a PDU set identifier and indicate the last transmitted PDU, the last discarded PDU, or the next expected PDU within the sequence of the PDU set. For example, referring to Figure 6 , the PDU set information for a PDU set received at 618 may include a PDU set identifier and indicate the last transmitted PDU, the last discarded PDU, or the next expected PDU within the sequence of the PDU set. In another example, referring to Figure 7 , the PDU set information for a PDU set received at 719 may include a PDU set identifier and indicate the last transmitted PDU, the last discarded PDU, or the next expected PDU within the sequence of the PDU set.

[0129] In some aspects, the PDU set information may be received from the AMF and included in one of an NG handover request message from the source cell via the AMF or an NG AP handover request message from the source cell via the AMF. For example, referring to Figure 7 , at 719, the PDU set information may be received from the AMF 708. The PDU set information received at 719 may be included in one of an NG handover request message from the source cell 704 via the AMF 708 or an NG AP handover request message from the source cell 704 via the AMF 708.

[0130] In some aspects, the buffered data may include an uplink PDU set in which at least one PDU has been received from the UE at the source cell and there may be at least one remaining PDU, and the PDU set information may be received for each data radio bearer having at least one associated PDU set for the UE. For example, referring to Figure 8 , the buffered data received at 818 may include an uplink PDU set in which at least one PDU has been received from the UE 802 at the source cell 804 and there may be at least one remaining PDU, and the PDU set information may be received for each data radio bearer having at least one associated PDU set for the UE 802. In another example, referring to Figure 9 , the buffered data received at 918 may include an uplink PDU set in which at least one PDU has been received from the UE 902 at the source cell 904 and there may be at least one remaining PDU, and the PDU set information may be received for each data radio bearer having at least one associated PDU set for the UE 902.

[0131] In some aspects, the PDU set information may be received from the UE. For example, referring to Figure 9 , at 919, the target cell 906 may receive the PDU set information from the UE 902.

[0132] In some aspects, the PDU set information may be included in the UE assistance information in the RRC message from the UE. Figure 9 , the PDU set information received at 919 may be included in the UE assistance information in the RRC message from UE 902.

[0133] In some aspects, the PDU set information may include a PDU set identifier for each of the one or more uplink PDU sets for which the UE initiates transmissions to the source cell. Figure 9 The PDU set information received at 919 may include a PDU set identifier for each of the one or more uplink PDU sets for which the UE 902 initiates transmission to the source cell 904.

[0134] In some aspects, for each uplink PDU set in one or more uplink PDU sets, the PDU set information may include a sequence number of the next expected reception within the sequence of PDUs in the corresponding PDU set. Figure 9 For each uplink PDU set in the one or more uplink PDU sets, the PDU set information received at 919 may include an expected next received sequence number within a sequence of PDUs in the corresponding PDU set.

[0135] In some aspects, for each uplink PDU set in the uplink PDU set, the PDU set information may include a sequence number of a last discarded PDU within a PDU sequence in the corresponding PDU set. Figure 8 The PDU set information received by the target cell 806 at 818 may include a sequence number of the last discarded PDU within the PDU sequence in the corresponding PDU set.

[0136] In some aspects, for each of the one or more PDU sets, the PDU set information may further include at least one of a PDU size or a content criterion. Figure 6 For each of the one or more PDU sets, the PDU set information received at 618 may also include at least one of a PDU size or content criteria. Figure 7 For each of the one or more PDU sets, the PDU set information received at 719 may also include at least one of a PDU size or content criteria. Figure 8, for each set of PDUs in one or more sets of PDUs, the PDU set information received at 818 may further include at least one of PDU size or content criteria. In yet another example, refer to Figure 9 , for each set of PDUs in one or more sets of PDUs, the PDU set information received at 919 may further include at least one of PDU size or content criteria.

[0137] At 1008, communication with the UE may be based on the PDU set information for the set of PDUs. For example, refer to Figure 6 , the target cell 606 may communicate with the UE 602 based on the PDU set information for the set of PDUs received at 618 (e.g., at 622). In another example, refer to Figure 7 , the target cell 706 may communicate with the UE 702 based on the PDU set information for the set of PDUs received at 719 (e.g., at 722). In another example, the target cell 806 may communicate with the UE 802 based on the PDU set information for the set of PDUs received at 818 (e.g., at 822). In yet another example, the target cell 906 may communicate with the UE 902 based on the PDU set information for the set of PDUs received at 919 (e.g., at 922). In some aspects, 1008 may be performed by the PDU set component 199.

[0138] Figure 11 is a flowchart 1100 of a wireless communication method. The method may be performed at a base station or other network entity configured as a source cell (e.g., Figure 14 the base station 102, CU 110, DU 130, RU 140, base station 310, source cell 604, source cell 704, source cell 804, source cell 904, or network entity 1402 in a hardware implementation of). For example, the method may be performed by a base station in aggregation or by one or more components of a base station. The method helps to improve the handling of sets of PDUs during mobility events of the UE such as RRC reconfiguration with a synchronization event (e.g., handover, PSCell change, or RRC re - establishment). Aspects presented herein may help prevent data loss and facilitate more efficient communication related to mobility events between the network and the UE.

[0139] As Figure 11 shown, at 1102, a part of a set of PDUs may be transmitted or received with the UE. For example, refer to Figure 6 , at 612, the source cell 604 may transmit a part of a set of PDUs to the UE 602. In another example, refer to Figure 7, at 712, the source cell 704 may transmit a portion of the PDU set to the UE 702. In another example, refer to Figure 8 , at 812, the source cell 804 may receive a portion of the PDU set from the UE 802. In yet another example, refer to Figure 9 , at 912, the source cell 904 may receive a portion of the PDU set from the UE 902. In some aspects, 1102 may be performed by the PDU set component 199.

[0140] At 1104, a handover of the UE to the target cell may be initiated. For example, refer to Figure 6 , at 618, the source cell 604 may initiate a handover of the UE 602 to the target cell 606. In another example, refer to Figure 7 , at 718, the source cell 704 may send a handover message to the AMF 708, and at 719, the AMF 708 may send a handover message to the target cell 706. In another example, refer to Figure 8 , at 818, the source cell 804 may initiate a handover of the UE 802 to the target cell 806. In yet another example, refer to Figure 9 , at 918, the source cell 904 may initiate a handover of the UE 902 to the target cell 806. In some aspects, 1104 may be performed by the PDU set component 199.

[0141] At 1106, buffered data for the PDU set may be provided to the target cell. For example, refer to Figure 6 , at 618, the source cell 604 may provide buffered data for the PDU set to the target cell 606. In another example, refer to Figure 7 , at 718, the source cell 704 may provide buffered data to the AMF 708, and at 719, the AMF 708 may provide buffered data to the target cell 706. In another example, refer to Figure 8 , at 818, the source cell 804 may provide buffered data for the PDU set to the target cell 806. In yet another example, refer to Figure 9 , at 918, the source cell 904 may provide buffered data for the PDU set to the target cell 906. In some aspects, 1106 may be performed by the PDU set component 199.

[0142] At 1108, PDU set information for the PDU set may be provided to the target cell. For example, refer to Figure 6 , at 618, the source cell 604 may provide PDU set information for the PDU set to the target cell 606. In another example, refer to Figure 7, at 718, the source cell 704 may provide PDU set information for a PDU set to the AMF 708, and at 719, the AMF 708 may provide the PDU set information to the target cell 706. In another example, referring to Figure 8 , at 818, the source cell 804 may provide PDU set information for a PDU set to the target cell 806. In some aspects, 1106 may be performed by the PDU set component 199.

[0143] In some aspects, the PDU set information may be transmitted via the Xn interface between the target cell and the source cell. For example, referring to Figure 6 , at 618, the source cell 604 may transmit the PDU set information to the target cell 606 via the Xn interface between the target cell 606 and the source cell 604. In another example, referring to Figure 8 , the source cell 804 may transmit the PDU set information to the target cell 806 via the Xn interface between the target cell 806 and the source cell 804.

[0144] In some aspects, the PDU set information may be included in one of an Xn handover request message, an Xn PDCP status transfer message, or an early status transfer message. For example, referring to Figure 6 , the PDU set information transmitted by the source cell 604 at 618 may be included in one of an Xn handover request message, an Xn PDCP status transfer message, or an early status transfer message. In another example, referring to Figure 8 , the PDU set information transmitted by the source cell 804 at 818 may be included in one of an Xn handover request message, an Xn PDCP status transfer message, or an early status transfer message.

[0145] In some aspects, the PDU set information may be provided to the AMF in one of an NG handover requirement message or an NG AP handover request message for forwarding to the target cell. For example, referring to Figure 7 , at 718, the source cell 704 may provide the PDU set information to the AMF 708 in one of an NG handover requirement message or an NG AP handover request message for forwarding to the target cell 706 (e.g., at 719).

[0146] In some aspects, the buffered data includes a downlink PDU set in which at least one PDU has been sent from the source cell to the UE and there is at least one remaining PDU to be sent to the UE. For example, referring to Figure 6 , the buffered data transmitted by the source cell 604 at 618 may include a downlink PDU set in which at least one PDU has been sent from the source cell 604 to the UE 602 and there is at least one remaining PDU to be sent to the UE 602. In another example, referring toFigure 7 At 718, the buffered data transmitted by the source cell 704 may include a set of downlink PDUs in which at least one PDU has been sent from the source cell 704 to the UE 702 and there is at least one remaining PDU to be sent to the UE 702.

[0147] In some aspects, the PDU set information for a set of PDUs may include a PDU set identifier and further indicate the last sent PDU, the last discarded PDU, or the next expected PDU within the sequence of the PDU set. For example, referring to Figure 6 At 618, the PDU set information transmitted by the source cell 604 may include a PDU set identifier and further indicate the last sent PDU, the last discarded PDU, or the next expected PDU within the sequence of the PDU set. In another example, referring to Figure 7 At 718, the PDU set information transmitted by the source cell 704 may include a PDU set identifier and further indicate the last sent PDU, the last discarded PDU, or the next expected PDU within the sequence of the PDU set.

[0148] In some aspects, the PDU set may be an uplink PDU set. For example, referring to Figure 8 At 812, the PDU set received by the source cell 804 is an uplink PDU set. In another example, referring to Figure 9 At 912, the PDU set received by the source cell 904 is an uplink PDU set.

[0149] In some aspects, the PDU set information may include the PDU set identifier of an uplink PDU set in which the source cell has received at least one PDU from the UE and has at least one remaining PDU from the UE, and the PDU set information includes the sequence number of the next expected received PDU within the PDU sequence of the corresponding PDU set. For example, referring to Figure 8 At 818, the PDU set information transmitted by the source cell 804 may include the PDU set identifier of each of one or more uplink PDU sets in which the source cell 804 has received at least one PDU from the UE 802 and has at least one remaining PDU from the UE, and the PDU set information includes the sequence number of the next expected received PDU within the PDU sequence of the corresponding PDU set.

[0150] In some aspects, the PDU set information may include the sequence number of the last discarded PDU within the PDU sequence of the corresponding PDU set. For example, referring to Figure 8At 818, the PDU set information transmitted by the source cell 804 may include the sequence number of the last discarded PDU within the PDU sequence in the corresponding PDU set.

[0151] In some aspects, the PDU set information may further include at least one of the PDU size or the content criterion for the PDU set. For example, referring to Figure 6 at 618, the PDU set information transmitted by the source cell 604 may further include at least one of the PDU size or the content criterion for the PDU set. In another example, referring to Figure 7 at 718, the PDU set information transmitted by the source cell 704 may further include at least one of the PDU size or the content criterion for the PDU set. In another example, at 818, the PDU set information transmitted by the source cell 804 may further include at least one of the PDU size or the content criterion for the PDU set.

[0152] Figure 12 is a flowchart 1200 of a method for wireless communication. The method may be performed at a UE (e.g., UE 104, UE 350, UE 602, UE 702, UE 802, UE 902, or device 13). The method helps to improve the handling of PDU sets by the UE when the UE experiences a mobility event such as an RRC reconfiguration with a synchronization event (e.g., handover, PSCell change, or RRC re - establishment). Aspects presented herein may help prevent data loss and facilitate more efficient communication related to mobility events between the network and the UE.

[0153] As Figure 12 shown, at 1202, a portion of an uplink PDU may be transmitted to the source cell. For example, referring to Figure 9 at 912, UE 902 may transmit a portion of an uplink PDU to the source cell 904. In some aspects, 1202 may be performed by the PDU set component 198. For example, Figure 9 illustrates an example of a UE transmitting an uplink PDU.

[0154] At 1204, PDU set information for the uplink PDU set may be provided to the target cell to which the UE is handing over from the source cell. For example, referring to Figure 9 at 919, UE 902 may provide PDU set information for the uplink PDU set to the target cell 906 to which UE 902 is handing over from the source cell 904. In some aspects, 1208 may be performed by the PDU set component 198. As an example, Figure 9 illustrates an example of a UE transmitting PDU set information to the target cell.

[0155] In some aspects, the PDU information may be included in an RRC message from the UE. For example, referring to Figure 9 , the PDU set information provided by UE 902 at 919 may be included in an RRC message from UE 902.

[0156] In some aspects, the PDU set information may include a PDU set identifier for an uplink PDU set in which the UE sends at least one PDU to a source cell and has at least one remaining PDU to send, and the PDU set information includes a sequence number within the PDU sequence of the corresponding PDU set that the target cell expects to receive next. For example, referring to Figure 9 , the PDU set information provided by UE 902 at 919 may include a PDU set identifier for an uplink PDU set in which UE 902 sends at least one PDU to source cell 904 and has at least one remaining PDU to send, and the PDU set information includes a sequence number within the PDU sequence of the corresponding PDU set that target cell 906 expects to receive next.

[0157] In some aspects, the PDU set information may further include at least one of a PDU size or content criterion. For example, referring to Figure 9 , the PDU set information provided by UE 902 at 919 may further include at least one of a PDU size or content criterion.

[0158] At 1206, the remainder of the uplink PDU set may be sent to the target cell after handover to the target cell. For example, referring to Figure 9 , at 922, the UE may send the remainder of the uplink PDU set to target cell 906 after handover to target cell 906. In some aspects, 1206 may be performed by PDU set component 198.

[0159] Figure 13 FIG. 1300 is a diagram illustrating an example of a hardware implementation for apparatus 1304. Apparatus 1304 may be a UE, a component of a UE, or may implement UE functionality. In some aspects, apparatus 1304 may include at least one cellular baseband processor 1324 (also referred to as a modem or processor circuitry) coupled to one or more transceivers 1322 (e.g., cellular RF transceivers). The cellular baseband processor 1324 may include on-chip memory 1324'. In some aspects, apparatus 1304 may further include one or more subscriber identity module (SIM) cards 1320 and an application processor 1306 (or processor circuitry) coupled to a secure digital (SD) card 1308 and a screen 1310. The application processor 1306 may include at least one on-chip memory 1306' (or memory circuitry). In some aspects, apparatus 1304 may further include BluetoothTMModule 1312, WLAN module 1314, SPS module 1316 (e.g., GNSS module), one or more sensor modules 1318 (e.g., barometric pressure sensor / altimeter; motion sensors such as inertial measurement unit (IMU), gyroscope, and / or accelerometer; light detection and ranging (LIDAR), radio assisted detection and ranging (RADAR), sound navigation and ranging (SONAR), magnetometer, audio, and / or other technologies for positioning), additional memory module 1326, power source 1330, and / or camera 1332. The Bluetooth module 1312, WLAN module 1314, and SPS module 1316 may include an on-chip transceiver (TRX) (or in some cases, only a receiver (RX)). The Bluetooth module 1312, WLAN module 1314, and SPS module 1316 may include their own dedicated antennas and / or communicate using antenna 1380. The cellular baseband processor 1324 communicates with the UE 104 and / or with the RU associated with the network entity 1302 via one or more antennas 1380 through the transceiver 1322. The cellular baseband processor 1324 and the application processor 1306 may each separately include computer-readable media / memory 1324', 1306'. The additional memory module 1326 may also be considered computer-readable media / memory. Each computer-readable media / memory (e.g., 1324', 1306', 1326) may be non-transitory. The cellular baseband processor 1324 and the application processor 1306 are each responsible for general processing, including executing software stored on the computer-readable media / memory. The software, when executed by the cellular baseband processor 1324 / application processor 1306, causes the cellular baseband processor 1324 / application processor 1306 to perform the various functions described above. In some aspects, the software, when executed by the cellular baseband processor 1324 / application processor 1306, may be described as causing the device (e.g., which may be a UE) to perform the various functions described above. The cellular baseband processor 1324 and the application processor 1306 are configured to perform the various functions described above at least in part based on information stored in the memory. That is, the cellular baseband processor 1324 and the application processor 1306 may be configured to perform a first subset of the various functions described above without the information stored in the memory, and may be configured to perform a second subset of the various functions described above based on the information stored in the memory. The computer-readable media / memory may also be used to store data manipulated by the cellular baseband processor 1324 / application processor 1306 when executing the software. The cellular baseband processor 1324 / application processor 1306 may be components of the UE 350 and may include at least one of the memory 360 and / or the TX processor 368, RX processor 356, and controller / processor 359.In one configuration, device 1304 can be a processor chip (modem and / or application) and include only the cellular baseband processor 1324 and / or the application processor 1306, and in another configuration, device 1304 can be the entire UE (e.g., see. Figure 3 of 350) and include additional modules of device 1304.

[0160] As discussed above, the PDU set component 198 can be configured to: transmit a portion of the uplink PDU set to the source cell; provide PDU set information for the uplink PDU set to the target cell to which the UE is handing over from the source cell; and transmit the remainder of the uplink PDU set to the target cell after the handover to the target cell. The PDU set component 198 can be further configured to perform any aspect of the aspects described in the flowchart in Figure 12 and / or any aspect of the aspects performed by the UE in Figure 6 , Figure 7 , Figure 8 and / or Figure 9 . The PDU set component 198 can be within the cellular baseband processor 1324, the application processor 1306, or both the cellular baseband processor 1324 and the application processor 1306. The PDU set component 198 can be one or more hardware components specifically configured to perform the stated process / algorithm, implemented by one or more processors configured to perform the stated process / algorithm, stored in a computer-readable medium for implementation by one or more processors, or some combination of the above. When multiple processors are implemented, the multiple processors can perform the stated process / algorithm individually or in combination. As shown, device 1304 can include various components configured for various functions. In one configuration, device 1304, and specifically the cellular baseband processor 1324 and / or the application processor 1306, includes: components for transmitting a portion of the uplink PDU set to the source cell; components for providing PDU set information for the uplink PDU set to the target cell to which the UE is handing over from the source cell; and components for transmitting the remainder of the uplink PDU set to the target cell after the handover to the target cell. The device can also include components for performing any aspect of the aspects described in the flowchart in Figure 12 and / or any aspect of the aspects performed by the UE in Figure 6 , Figure 7 , Figure 8 and / or Figure 9A component of any aspect among the aspects performed by the UE in []. The component may be the PDU set component 198 of the device 1304 configured to perform the functions described by the component. As described above, the device 1304 may include a TX processor 368, an RX processor 356, and a controller / processor 359. Thus, in one configuration, the component may be the TX processor 368, the RX processor 356, and / or the controller / processor 359 configured to perform the functions described by the component.

[0161] Figure 14FIG. 1400 is a diagram illustrating an example of a hardware implementation for network entity 1402. In some instances, the network entity may be a source cell in handover, and in other instances, the network entity may be a target cell in handover. Network entity 1402 may be a base station, a component of a base station, or may implement base station functionality. Network entity 1402 may include at least one of CU 1410, DU 1430, or RU 1440. For example, depending on the layer functionality handled by the PDU set component 199, network entity 1402 may include CU 1410; both CU 1410 and DU 1430; each of CU 1410, DU 1430, and RU 1440; DU 1430; both DU 1430 and RU 1440; or RU 1440. CU 1410 may include at least one CU processor 1412 (or processor circuitry). CU processor 1412 may include at least one on-chip memory 1412' (or memory circuitry). In some aspects, CU 1410 may also include additional memory module 1414 and communication interface 1418. CU 1410 communicates with DU 1430 via a midhaul link such as the F1 interface. DU 1430 may include at least one DU processor 1432 (or processor circuitry). DU processor 1432 may include at least one on-chip memory 1432' (or memory circuitry). In some aspects, DU 1430 may also include additional memory module 1434 and communication interface 1438. DU 1430 communicates with RU 1440 via a fronthaul link. RU 1440 may include at least one RU processor 1442 (or processor circuitry). RU processor 1442 may include at least one on-chip memory 1442' (or memory circuitry). In some aspects, RU 1440 may also include additional memory module 1444, one or more transceivers 1446, antenna 1480, and communication interface 1448. RU 1440 communicates with UE 104. On-chip memories 1412', 1432', 1442' and additional memory modules 1414, 1434, 1444 may each be considered a computer-readable medium / memory. Each computer-readable medium / memory may be non-transitory. Each of processors 1412, 1432, 1442 is responsible for general processing, including executing software stored on the computer-readable medium / memory. The software, when executed by the corresponding processor, causes the processor to perform the various functions described above. The computer-readable medium / memory may also be used to store data manipulated by the processor when executing the software.

[0162] As discussed above, network entity 1402 may be configured as a target cell (e.g., in handover), and the PDU set component 199 may be configured to: receive a handover message for the UE from the source cell; receive buffered data for one or more PDU sets in transition between the source cell and the UE; receive PDU set information for one or more PDU sets; and communicate with the UE based on the PDU set information for one or more PDU sets. The PDU set component 199 may be further configured to perform any of the aspects described in the flowcharts associated with Figure 10 and / or any of the aspects performed by the target cell in Figure 6 , Figure 7 , Figure 8 and / or Figure 9 . As further discussed above, network entity 1402 may be configured as a source cell (e.g., in handover), and the PDU set component 199 may be configured to: transmit or receive a portion of a PDU set with the UE; initiate a handover of the UE to the target cell; provide buffered data for the PDU set to the target cell; and provide PDU set information for the PDU set to the target cell. The PDU set component 199 may be further configured to perform any of the aspects described in the flowcharts associated with Figure 11 and / or any of the aspects performed by the target cell in Figure 6 , Figure 7 , Figure 8 and / or Figure 9Any aspect in the aspects performed by the source cell. The PDU set component 199 can be within one or more processors of one or more of the CU 1410, DU 1430, and RU 1440. The PDU set component 199 can be one or more hardware components specifically configured to perform the stated process / algorithm, implemented by one or more processors configured to perform the stated process / algorithm, stored in a computer-readable medium for implementation by one or more processors, or some combination of the above. When multiple processors are implemented, the multiple processors can perform the stated process / algorithm individually or in combination. The network entity 1402 can include various components configured for various functions. In one configuration, the network entity 1402 includes components for: receiving a handover message for the UE from the source cell; receiving buffered data for one or more PDU sets in transition between the source cell and the UE; receiving PDU set information for one or more PDU sets; and communicating with the UE based on the PDU set information for one or more PDU sets. In another configuration, the network entity 1402 includes components for: transmitting or receiving a portion of a PDU set with the UE; initiating a handover of the UE to the target cell; providing the buffered data for the PDU set to the target cell; and providing the PDU set information for the PDU set to the target cell. The network entity may also include components for performing any aspect in the aspects described in the flowchart associated with Figure 10 or Figure 11 and / or any aspect performed by the target cell or the source cell described in Figure 6 、 Figure 7 、 Figure 8 and / or Figure 9 . The components can be the PDU set component 199 of the network entity 1402 configured to perform the functions described by the components. As described above, the network entity 1402 can include a TX processor 316, an RX processor 370, and a controller / processor 375. Thus, in one configuration, the components can be the TX processor 316, the RX processor 370, and / or the controller / processor 375 configured to perform the functions described by the components.

[0163] Figure 15FIG. 1500 is a diagram illustrating an example of a hardware implementation for network entity 1560. In one example, network entity 1560 may be within core network 120. Network entity 1560 may include network processor 1512. Network processor 1512 may include on-chip memory 1512'. In some aspects, network entity 1560 may further include additional memory module 1514. Network entity 1560 communicates with CU 1502 directly (e.g., backhaul link) or indirectly (e.g., through RIC) via network interface 1580. On-chip memory 1512' and additional memory module 1514 may each be considered computer-readable media / memory. Each computer-readable media / memory may be non-transitory. Processor 1512 is responsible for general processing, including executing software stored on the computer-readable media / memory. The software, when executed by the corresponding processor, causes the processor to perform the various functions described above. The computer-readable media / memory may also be used to store data manipulated by the processor when executing the software.

[0164] As discussed above, PDU set component 199 is configured to perform the features described above for AMF 708 (e.g., receive a handover message from a source cell and send a handover message to a target cell, receive buffered data for a PDU set in transition between the source cell and the UE from the source cell and send the buffered data to the target cell, and / or receive PDU set information for the PDU set from the source cell and send the PDU set information to the target cell). PDU set component 199 may be within processor 1512. PDU set component 199 may be one or more hardware components specifically configured to perform the stated processes / algorithms, implemented by one or more processors configured to perform the stated processes / algorithms, stored in a computer-readable medium for implementation by one or more processors, or some combination of the above. When multiple processors are implemented, the multiple processors may perform the stated processes / algorithms individually or in combination. Network entity 1560 may include various components configured for various functions. In one configuration, network entity 1560 includes: components for receiving a handover message from a source cell and components for sending a handover message to a target cell; components for receiving buffered data for a PDU set in transition between the source cell and the UE from the source cell and components for sending the buffered data to the target cell; and / or components for receiving PDU set information for the PDU set from the source cell and components for sending the PDU set information to the target cell. The components may be PDU set component 199 of network entity 1560 configured to perform the functions recited by the components.

[0165] It should be understood that the specific order or hierarchy of the boxes in the disclosed process / flowchart is merely illustrative of an example method. It should be understood that, based on design preferences, the specific order or hierarchy of the boxes in the process / flowchart can be rearranged. Additionally, some boxes can be combined or omitted. The appended method claims present the elements of the various boxes in a sample order, but are not limited to the specific order or hierarchy presented.

[0166] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects. Thus, the claims are not limited to the aspects described herein, but should be accorded the full scope consistent with the language of the claims. References to elements in the singular form do not imply "one and only one" unless specifically stated, but rather "one or more." Terms such as "if," "when," and "while" do not imply a direct temporal relationship or reaction. That is, phrases such as "when... " do not imply an immediate action in response to the occurrence of an action or during the occurrence of an action, but simply imply that if the condition is met, the action will occur, without a specific or immediate time limitation for the occurrence of the action. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or having an advantage over other aspects. Unless specifically stated, the term "some" means one or more. Combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "any combination of A, B, C, or any of them," including any combination of A, B, and / or C, may include multiple A's, multiple B's, or multiple C's. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "any combination of A, B, C, or any of them" can be only A, only B, only C, A and B, A and C, B and C, or A and B and C, where any such combination may contain one or more members of A, B, or C. A set should be construed as a collection of elements, where the number of elements is one or more. Thus, for a set of X, X will include one or more elements. When at least one processor (e.g., one or more processors) is configured to perform a set of functions, the at least one processor is configured to perform the set of functions either individually or in any combination. Thus, each processor in the at least one processor may be configured to perform a particular subset of the set of functions, where the subset is the complete set, a proper subset of the set, or the empty subset of the set. If a first device receives data from or sends data to a second device, the data may be received / sent directly between the first device and the second device, or indirectly between the first device and the second device through a collection of devices. A device configured to "output" data or "provide" data (such as a transmission, signal, or message) may, for example, transmit the data with a transceiver, or may convey the data to a device that transmits the data.A device configured to "obtain" data (such as a transmission, signal, or message) can receive the data, for example, using a transceiver, or can obtain the data from a device that receives the data. The information stored in the memory includes instructions and / or data. All structural and functional equivalents of the elements described throughout the aspects of this disclosure that are known or will later be known to those of ordinary skill in the art are expressly incorporated herein by reference and are covered by the claims. Additionally, nothing disclosed herein is intended to be dedicated to the public, whether or not such disclosure is expressly recited in the claims. The words "module", "mechanism", "element", "device", etc. shall not be used in place of the word "component". Accordingly, no claim element shall be construed as a means-plus-function unless the element is expressly recited using the phrase "means for".

[0167] As used herein, the phrase "based on" should not be construed to refer to a closed set of information, one or more conditions, one or more factors, etc. In other words, the phrase "based on A" (where "A" can be information, a condition, a factor, etc.) should be construed as "at least based on A" unless stated otherwise specifically.

[0168] The following aspects are merely illustrative and can be combined with other aspects or teachings described herein without limitation.

[0169] Aspect 1 is a method for wireless communication at a target cell, the method comprising: receiving a handover message for a UE originating from a source cell; receiving buffered data for one or more sets of PDUs in transition between the source cell and the UE; receiving PDU set information for the one or more sets of PDUs; and communicating with the UE based on the PDU set information for the one or more sets of PDUs.

[0170] Aspect 2 is the method according to aspect 1, wherein the PDU set information is received from the source cell.

[0171] Aspect 3 is the method according to aspect 2, wherein the PDU set information is received via an Xn interface between the target cell and the source cell.

[0172] Aspect 4 is the method according to aspect 3, wherein the PDU set information is included in at least one of the following: an Xn handover request message, an Xn PDCP status transfer message, or an early status transfer message.

[0173] Aspect 5 is the method according to any one of aspects 1 to 4, wherein the buffered data includes one or more downlink PDU sets in which at least one PDU has been sent from the source cell to the UE and there is at least one remaining PDU to be sent to the UE.

[0174] Aspect 6 is the method according to aspect 5, wherein the PDU set information for the PDU set includes a PDU set identifier and indicates the last transmitted PDU, the last discarded PDU, or the next expected PDU within the sequence of the PDU set.

[0175] Aspect 7 is the method according to any one of aspects 5 to 6, wherein the PDU set information is received from the AMF and is included in one of the following: an NG handover request message from the source cell via the AMF or an NG AP handover request message from the source cell via the AMF.

[0176] Aspect 8 is the method according to aspect 1, wherein the buffered data includes one or more uplink PDU sets in which at least one PDU is received from the UE at the source cell and there is at least one remaining PDU, and the PDU set information is received for each data radio bearer having at least one associated PDU set for the UE.

[0177] Aspect 9 is the method according to aspect 8, wherein the PDU set information is included in UE assistance information in an RRC message from the UE.

[0178] Aspect 10 is the method according to aspect 9, wherein the PDU set information is included in UE assistance information in an RRC message from the UE.

[0179] Aspect 11 is the method according to aspect 10, wherein the PDU set information includes a PDU set identifier for each uplink PDU set among the one or more uplink PDU sets for which the UE initiated transmission to the source cell.

[0180] Aspect 12 is the method according to aspect 11, wherein for each uplink PDU set among the one or more uplink PDU sets, the PDU set information includes the sequence number of the next expected received PDU within the PDU sequence of the corresponding PDU set.

[0181] Aspect 13 is the method according to aspect 11, wherein for each uplink PDU set among the one or more uplink PDU sets, the PDU set information includes the sequence number of the last discarded PDU within the PDU sequence of the corresponding PDU set.

[0182] Aspect 14 is the method according to any one of Aspects 1 to 13, wherein for each PDU set in the one or more PDU sets, the PDU set information further includes at least one of a PDU size or a content criterion.

[0183] Aspect 15 is a method for wireless communication at a source cell, the method comprising: transmitting or receiving a portion of a PDU set with a UE; initiating a handover of the UE to a target cell; providing buffered data for the PDU set to the target cell; and providing PDU set information for the PDU set to the target cell.

[0184] Aspect 16 is the method according to Aspect 15, wherein the PDU set information is transmitted via an Xn interface between the target cell and the source cell.

[0185] Aspect 17 is the method according to Aspect 16, wherein the PDU set information is included in one of the following: an Xn handover request message, an Xn PDCP status transfer message, or an early status transfer message.

[0186] Aspect 18 is the method according to Aspect 15, wherein the PDU set information is provided to an AMF in one of an NG handover requirement message or an NGAP handover request message for forwarding to the target cell.

[0187] Aspect 19 is the method according to any one of Aspects 15 to 18, wherein the buffered data includes a downlink PDU set in which at least one PDU has been sent from the source cell to the UE and there is at least one remaining PDU to be sent to the UE.

[0188] Aspect 20 is the method according to Aspect 19, wherein the PDU set information for the PDU set includes a PDU set identifier and further indicates the last sent PDU, the last discarded PDU, or the next expected PDU within the sequence of the PDU set.

[0189] Aspect 21 is the method according to Aspect 15, wherein the PDU set is an uplink PDU set.

[0190] Aspect 22 is the method according to Aspect 21, wherein the PDU set information includes a PDU set identifier for each uplink PDU set in the one or more uplink PDU sets in which the source cell has received at least one PDU from the UE and has at least one remaining PDU from the UE, and the PDU set information includes the expected next received sequence number within the PDU sequence of the corresponding PDU set.

[0191] Aspect 23 is the method according to aspect 21, wherein the PDU set information further includes at least one of a PDU size or a content criterion for the PDU set.

[0192] Aspect 24 is the method according to any one of aspects 15 to 23, wherein the PDU set information further includes at least one of a PDU size or a content criterion for the PDU set.

[0193] Aspect 25 is a method for wireless communication at a UE, the method comprising: transmitting a part of an uplink PDU set to a source cell; providing PDU set information for the uplink PDU set to a target cell to which the UE is handing over from the source cell; and transmitting the remaining part of the uplink PDU set to the target cell after the handover to the target cell.

[0194] Aspect 26 is the method according to aspect 25, wherein the PDU set information is included in an RRC message from the UE.

[0195] Aspect 27 is the method according to any one of aspects 25 to 26, wherein the PDU set information includes a PDU set identifier for each uplink PDU set in one or more uplink PDU sets in which the UE has transmitted at least one PDU and has at least one remaining PDU to transmit, and the PDU set information includes an expected next received sequence number within a PDU sequence in the target cell corresponding PDU set.

[0196] Aspect 28 is the method according to any one of aspects 25 to 27, wherein for each uplink PDU set in the one or more uplink PDU sets, the PDU set information further includes at least one of a PDU size or a content criterion.

[0197] Aspect 29 is a device for wireless communication at a target cell, the device comprising: a memory; and at least one processor, the at least one processor being coupled to the memory and being configured to implement any one of aspects 1 to 14 alone or in any combination at least partially based on information stored in the memory.

[0198] In aspect 30, the device according to aspect 29 further includes: at least one transceiver, the at least one transceiver being coupled to the at least one processor.

[0199] Aspect 31 is an apparatus for wireless communication at a source cell, the apparatus comprising: a memory; and at least one processor coupled to the memory, and the at least one processor is configured to implement any one of Aspects 15 to 24 alone or in any combination, at least in part based on information stored in the memory.

[0200] In aspect 32, the apparatus according to aspect 31 further comprises: at least one transceiver coupled to the at least one processor.

[0201] Aspect 33 is an apparatus for wireless communication at a UE, the apparatus comprising: a memory; and at least one processor coupled to the memory, and the at least one processor is configured to implement any one of Aspects 25 to 28 alone or in any combination, at least in part based on information stored in the memory.

[0202] In aspect 34, the apparatus according to aspect 33 further comprises: at least one transceiver coupled to the at least one processor.

[0203] Aspect 35 is an apparatus for wireless communication, the apparatus comprising: means for implementing any one of Aspects 1 to 14.

[0204] Aspect 36 is an apparatus for wireless communication, the apparatus comprising: means for implementing any one of Aspects 15 to 24.

[0205] Aspect 37 is an apparatus for wireless communication, the apparatus comprising: means for implementing any one of Aspects 25 to 28.

[0206] Aspect 38 is a computer-readable medium (e.g., a non-transitory computer-readable medium) storing computer-executable code, the computer-executable code causing the at least one processor to implement any one of Aspects 1 to 14 when executed by the at least one processor.

[0207] Aspect 39 is a computer-readable medium (e.g., a non-transitory computer-readable medium) storing computer-executable code, the computer-executable code causing the at least one processor to implement any one of Aspects 15 to 24 when executed by the at least one processor.

[0208] Aspect 40 is a computer-readable medium (e.g., a non-transitory computer-readable medium) storing computer-executable code, the computer-executable code causing the at least one processor to implement any one of Aspects 25 to 28 when executed by the at least one processor.

Claims

1. An apparatus for wireless communication at a target cell, the apparatus comprising: at least one memory; and at least one processor, the at least one processor coupled to the at least one memory, and at least partially based on information stored in the at least one memory, the at least one processor is configured, alone or in combination, to cause the target cell to: receive a handover message for a user equipment (UE) originating from a source cell; receive buffered data for one or more sets of protocol data units (PDUs) in transition between the source cell and the UE; receive PDU set information for the one or more sets of PDUs; and communicate with the UE based on the PDU set information for the one or more sets of PDUs.

2. The apparatus according to claim 1, wherein the PDU set information is from the source cell.

3. The apparatus according to claim 2, wherein the at least one processor is configured, alone or in any combination, to cause the target cell to receive the PDU set information via an Xn interface between the target cell and the source cell.

4. The apparatus according to claim 3, wherein the PDU set information is included in at least one of the following: an Xn handover request message, an Xn packet data convergence protocol (PDCP) status transfer message, or an early status transfer message.

5. The apparatus according to claim 2, wherein the buffered data includes one or more sets of downlink PDUs in which at least one PDU has been sent from the source cell to the UE and there is at least one remaining PDU to be sent to the UE.

6. The apparatus according to claim 5, wherein the PDU set information for a set of PDUs includes a PDU set identifier and indicates the last sent PDU, the last discarded PDU, or the next expected PDU within the sequence of the set of PDUs.

7. The apparatus according to claim 5, wherein the PDU set information is received from an access and mobility management function (AMF) and is included in one of the following: an NG handover requirement message from the source cell via the AMF, or an NG application protocol (AP) handover request message from the source cell via the AMF.

8. The apparatus according to claim 1, wherein the buffered data includes one or more sets of uplink PDUs in which at least one PDU has been received from the UE at the source cell and there is at least one remaining PDU, and the PDU set information is received for each data radio bearer having at least one associated set of PDUs for the UE.

9. The apparatus according to claim 1, wherein for each set of PDUs in the one or more sets of PDUs, the PDU set information further includes at least one of a PDU size or a content criterion.

10. The apparatus according to claim 1, the apparatus further comprising: At least one transceiver, the at least one transceiver being coupled to the at least one processor, wherein the at least one processor is configured to transmit or receive communications with the UE via the at least one transceiver.

11. An apparatus for wireless communication at a source cell, the apparatus comprising: at least one memory; and at least one processor, the at least one processor being coupled to the at least one memory and, at least in part based on information stored in the at least one memory, the at least one processor being configured, alone or in any combination, to cause the source cell to: transmit or receive a portion of a set of protocol data units (PDUs) with a user equipment (UE); initiate a handover of the UE to a target cell; provide buffered data for the set of PDUs to the target cell; and provide PDU set information for the set of PDUs to the target cell.

12. The apparatus of claim 11, wherein the at least one processor is configured, alone or in any combination, to cause the source cell to transmit the PDU set information via an Xn interface between the target cell and the source cell, and wherein the PDU set information is included in one of the following: an Xn handover request message, an Xn packet data convergence protocol (PDCP) status transfer message, or an early status transfer message.

13. The apparatus of claim 11, wherein the at least one processor is configured, alone or in any combination, to cause the source cell to provide the PDU set information to an access and mobility management function (AMF) in one of the following for forwarding to the target cell: an NG handover requirement message, or an NG application protocol (AP) handover request message.

14. The apparatus of claim 11, wherein the buffered data comprises a downlink PDU set in which at least one PDU has been sent from the source cell to the UE and there is at least one remaining PDU to be sent to the UE, and wherein the PDU set information for the set of PDUs comprises a PDU set identifier and further indicates the last sent PDU, the last discarded PDU, or the next expected PDU within the sequence of the PDU set.

15. The apparatus of claim 11, wherein the PDU set is an uplink PDU set, and wherein the PDU set information comprises at least one of the following: a PDU set identifier of the uplink PDU set in which the source cell has received at least one PDU from the UE and has at least one remaining PDU from the UE, and the PDU set information comprises the sequence number of the next expected received PDU within the PDU sequence of the corresponding PDU set, the sequence number of the last discarded PDU within the PDU sequence of the corresponding PDU set, the PDU size, or content criteria for the set of PDUs.

16. The apparatus of claim 11, the apparatus further comprising: At least one transceiver, the at least one transceiver being coupled to the at least one processor, wherein the at least one transceiver is configured to transmit or receive, via the at least one transceiver, the portion of the set of PDUs with the UE.

17. A method for wireless communication at a target cell, the method comprising: receiving a handover message for a user equipment (UE) originating from a source cell; receiving buffered data for one or more sets of protocol data units (PDUs) in transition between the source cell and the UE; receiving PDU set information for the one or more sets of PDUs; and communicating with the UE based on the PDU set information for the one or more sets of PDUs.

18. The method according to claim 17, wherein the PDU set information is received from the source cell.

19. The method according to claim 18, wherein the PDU set information is received via an Xn interface between the target cell and the source cell, and wherein the PDU set information is included in one of the following: an Xn handover request message, an Xn packet data convergence protocol (PDCP) status transfer message, or an early status transfer message.

20. The method according to claim 18, wherein the buffered data includes one or more downlink PDU sets in which at least one PDU has been sent from the source cell to the UE and there is at least one remaining PDU to be sent to the UE.

21. The method according to claim 20, wherein the PDU set information for a PDU set includes a PDU set identifier and indicates the last sent PDU, the last discarded PDU, or the next expected PDU within the sequence of the PDU set.

22. The method according to claim 20, wherein the PDU set information is received from an access and mobility management function (AMF) and is included in one of the following: an NG handover request message from the source cell via the AMF, or an NG application protocol (AP) handover request message from the source cell via the AMF.

23. The method according to claim 17, wherein the buffered data includes one or more uplink PDU sets in which at least one PDU has been received from the UE at the source cell and there is at least one remaining PDU, and the PDU set information is received for each data radio bearer having at least one associated PDU set for the UE.

24. The method according to claim 17, wherein for each PDU set of the one or more sets of PDUs, the PDU set information further includes at least one of a PDU size or a content criterion.

25. A method for wireless communication at a source cell, the method comprising: transmitting or receiving a portion of a set of protocol data units (PDUs) with a user equipment (UE); initiating a handover of the UE to a target cell; providing buffered data for the set of PDUs to the target cell; and Provide PDU set information for the PDU set to the target cell.

26. The method according to claim 25, wherein the PDU set information is transmitted through the Xn interface between the target cell and the source cell.

27. The method according to claim 26, wherein the PDU set information is included in one of the following: Xn handover request message, Xn packet data convergence protocol (PDCP) status transfer message, or Early status transfer message.

28. The method according to claim 25, wherein the PDU set information is provided to the access and mobility management function (AMF) for forwarding to the target cell in one of the following: NG handover requirement message, or NG application protocol (AP) handover request message.

29. The method according to claim 25, wherein the buffered data includes a downlink PDU set in which at least one PDU has been sent from the source cell to the UE and there is at least one remaining PDU to be sent to the UE, and wherein the PDU set information for the PDU set includes a PDU set identifier and further indicates the last sent PDU, the last discarded PDU, or the next expected PDU within the sequence of the PDU set.

30. The method according to claim 25, wherein the PDU set is an uplink PDU set, and wherein the PDU set information includes at least one of the following: The PDU set identifier of the uplink PDU set in which the source cell has received at least one PDU from the UE and has at least one remaining PDU from the UE, and the PDU set information includes the expected next received sequence number within the PDU sequence in the corresponding PDU set, The sequence number of the last discarded PDU within the PDU sequence in the corresponding PDU set, PDU size, or Content criteria for the PDU set.

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