Robust header compression indication after path change during handover

Abstract

Systems, methods, and apparatus are provided to: perform Packet Data Convergence Protocol (PDCP) decryption of packets to store the decrypted packets in a common buffer; perform PDCP reordering on the decrypted packets in the common buffer to generate a reordered packet stream; perform Robust Header Compression (ROHC) decompression on the reordered packet stream; and determine to reset the ROHC decompression based on a packet indication, wherein the packet indication includes a single bit in the PDCP header that is set to indicate the start of a ROHC reset based on a path transition during a handover from a source cell to a target cell.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 753,731, filed on October 31, 2018, which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present patent application relates generally to wireless communication systems, and more particularly to simultaneous connection handovers. Background Art

[0004] Wireless mobile communication technology uses various standards and protocols to transmit data between base stations and wireless mobile devices. Wireless communication system standards and protocols may include the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE); the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard, which is often referred to as Worldwide Interoperability for Microwave Access (WiMAX) by industry organizations; and the IEEE 802.11 standard for wireless local area networks (WLANs), which is often referred to as Wi-Fi by industry organizations. In the 3GPP radio access network (RAN) in the LTE system, the base station may include a RAN node such as an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (also often referred to as an Evolved Node B, an Enhanced Node B, an eNodeB, or an eNB) and / or a Radio Network Controller (RNC) in the E-UTRAN, which communicates with a wireless communication device referred to as a user equipment (UE). In the fifth generation (5G) wireless RAN, the RAN node may include a 5G node, a new radio (NR) node, or a gNodeB (gNB).

[0005] The RAN uses radio access technologies (RATs) to communicate between RAN nodes and UEs. The RAN may include a Global System for Mobile Communications (GSM), an Enhanced Data Rate for GSM Evolution (EDGE) RAN (GERAN), a Universal Terrestrial Radio Access Network (UTRAN), and / or an E-UTRAN, which provides access to communication services through a core network. Each of the RANs operates according to a specific 3GPP RAT. For example, the GERAN implements GSM and / or EDGE RAT, the UTRAN implements the Universal Mobile Telecommunications System (UMTS) RAT or other 3GPP RAT, and the E-UTRAN implements the LTE RAT.

[0006] The core network may be connected to the UE via a RAN node. The core network may include a serving gateway (SGW), a packet data network (PDN) gateway (PGW), an access network detection and selection function (ANDSF) server, an enhanced packet data gateway (ePDG) and / or a mobility management entity (MME). BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A protocol stack according to one embodiment is shown.

[0008] Figure 2 A security and reordering process according to one embodiment is shown.

[0009] Figure 3 A PDCP packet format according to one embodiment is shown.

[0010] Figure 4 A method according to one embodiment is shown.

[0011] Figure 5 A method according to another embodiment is shown.

[0012] Figure 6 A system according to one embodiment is shown.

[0013] Figure 7 An apparatus according to one embodiment is shown.

[0014] Figure 8 An exemplary interface according to one embodiment is shown.

[0015] Fig. 9 A control plane according to one embodiment is shown.

[0016] Fig.10 A user plane according to one embodiment is shown.

[0017] Fig.11 Components according to one embodiment are shown.

[0018] Fig.12 A system according to one embodiment is shown.

[0019] Fig.13 Components according to one embodiment are shown. DETAILED DESCRIPTION

[0020] Simultaneous connection handover can achieve the goal of 0 millisecond (ms) outage time in both LTE and NR. One of the architecture options is non-split bearer. This option may be the same or similar to the option used in enhanced mobile broadband (eMBB). If a non-split bearer architecture is considered, the UE may receive two data streams (one from the source cell (which may include the serving cell) and one from the target cell) during handover (HO).

[0021] For example, Figure 1A protocol stack 100 for a non-split bearer architecture to support simultaneous connection switching according to certain embodiments is shown. Specifically, Figure 1 A protocol stack for a serving cell is shown including a physical layer (shown as PHY 102), a medium access control (MAC) layer (shown as MAC 104), a radio link control (RLC) layer (shown as RLC 106), and a packet data convergence protocol (PDCP) layer (shown as PDCP 108). Similarly, the protocol stack for a target cell includes PHY 110, MAC 112, RLC 114, and PDCP 116.

[0022] Before switching, the UE may only be connected to the source (serving) cell. The UE may communicate with the source cell using a first protocol stack including PHY 118, MAC 120, RLC 122 and PDCP 124. The UE may be configured to receive a switching command that enables simultaneous connections during switching. Therefore, the UE may have prepared a second protocol stack including PHY 126, MAC 128, RLC 130 and PDCP 132 so that it can be used to communicate with the target cell once the UE receives the switching command. During switching, the UE may have completed a random access channel (RACH) process with the target cell. Therefore, during switching, the UE may be connected to both the source cell and the target cell.

[0023] like Figure 1 As shown, during the handover, the source (serving) cell may forward data to the target cell, which may process the data and send it to the UE. The data forwarded from the source cell to the serving cell may include a partial PDCP protocol data unit (PDU) with robust header compression (ROHC) and sequence number (SN). The UE may perform PDCP reordering 134 of the PDUs received from both the source cell and the target cell in the same buffer. However, after the path transition from the source cell to the target cell is completed, the ROHC decompression performed by the UE may no longer work because the source cell has initiated and is performing ROHC compression on the packets received from the source cell and the target cell. After the path transition, the target cell performs ROHC compression on the packets sent to the UE. Therefore, it is necessary to reset the ROHC decompression at the UE 208.

[0024] Figure 2 A security and reordering process 200 for a non-split bearer architecture is shown according to certain embodiments. Specifically, Figure 2 An example of downlink (DL) user plane switching for a non-split bearer architecture is shown.

[0025] On the network side, the serving gateway (shown as SGW 202) sends data (shown as data 1, 2, 3, and 4) to the source cell 204. If necessary, the source cell 204 processes ROHC and allocates a PDCP SN for each packet. The source cell 204 then forwards the partial PDCP PDU (after ROHC) and the SN to the target cell 206. In addition or alternatively, the source cell 204 processes integrity protection (for control plane (c-plane) data) and performs encryption before sending at least some of the data to the UE 208.

[0026] The PDCP entity of the target cell 206 may perform integrity protection (for c-plane data) and ciphering on only the partial PDCP PDUs received from the source cell 204 before sending them to the UE 208 .

[0027] On the UE receiver side (e.g., after the UE 208 determines the count of PDCP PDUs), the UE 208 may perform separate operations for each link to the source cell 204 and the target cell 206. For data received over the link to the source cell 204, the UE 208 performs PHY / MAC / RLC processing 210 (e.g., as in conventional LTE procedures), performs integrity protection checks (for c-plane data) and PDCP decryption 212, and stores packets in a common buffer 214 for reordering. Similarly, for data received over the link to the target cell 206, the UE 208 performs PHY / MAC / RLC processing 216, performs integrity protection checks (for c-plane data) and PDCP decryption 218, and stores packets in a common buffer 214 for reordering.

[0028] After the UE 208 performs PDCP reordering of the packets in the common buffer 214, the UE 208 performs ROHC decompression 220 and sends 222 the data to higher layers.

[0029] After the path transition, ROHC decompression 220 may not function and may need to be reset. For example, ROHC may include progressive compression, where the decompression of subsequent packets may depend on earlier packets. Therefore, once ROHC transitions from being performed by source cell 204 to being performed by target cell 206, UE 208 may no longer be able to use information received in earlier packets to decompress the current packet. However, conventional implementations do not provide a way to indicate to the UE which packet may start a ROHC reset.

[0030] Therefore, certain embodiments herein provide for a ROHC reset indication after a path transition during handover.

[0031] For example, one embodiment provides a single bit (1 bit) indication in the PDCP header to indicate a ROHC reset. Figure 3 A PDCP packet format 300 according to one embodiment is shown, where a reserved bit may be configured as a ROHC reset indicator 302. When the ROHC reset indicator 302 is set, it indicates to the UE that the packet may be used to start a ROHC reset. Figure 3 The format of the PDCP data PDU when a 12-bit SN length is used is shown. The format can be applicable to PDCP data PDUs carrying data from data radio bearers (DRBs) mapped on RLC AM (acknowledged mode) or RLC UM (unacknowledged mode).

[0032] In another embodiment, a new PDCP Control PDU may be created to indicate when the ROHC should be reset / initialized.

[0033] Figure 4 A method 400 for enabling a UE to perform a handover from a source cell to a target cell in a wireless network according to one embodiment is shown. In box 402, the method 400 processes packets received from a source cell and a target cell. In box 404, the method 400 performs a packet data convergence protocol (PDCP) decryption of the packets to store the decrypted packets in a common buffer. In box 406, the method 400 performs PDCP reordering on the decrypted packets in the common buffer to generate a reordered packet stream. In box 408, the method 400 performs a robust header compression (ROHC) decompression on the reordered packet stream. In box 410, the method 400 determines to reset the ROHC decompression based on the packet indication.

[0034] In one embodiment, the packet indication includes a single bit in the PDCP header that is set to indicate the start of the ROHC reset based on the path transition during the handover from the source cell to the target cell. The PDCP header may correspond to a PDCP data PDU carrying data from the DRB. The PDCP data PDU may correspond to one of the packets received from the target cell.

[0035] In another embodiment, the packet indication includes a PDCP control PDU configured to indicate the start of a ROHC reset.

[0036] Figure 5A method 500 for handover of a UE in a wireless communication system for a target cell is shown. In box 502, the method 500 receives a partial packet data convergence protocol (PDCP) protocol data unit (PDU) from a source cell in the wireless communication system, the partial PDCP PDU including robust header compression (ROHC) performed by the source cell. In box 504, the method 500 performs PDCP ciphering on the partial PDCP PDU to generate an encrypted PDCP PDU. In box 506, the method 500 sends the encrypted PDCP PDU to the UE. After releasing the source cell in box 508 to complete the path transition to the target cell, in box 510, the method 500 performs ROHC on data received from the core network of the wireless communication system, and in box 512, the method 500 generates a packet to indicate the start of the ROHC reset to the UE.

[0037] In one embodiment, the packet used to indicate the start of a ROHC reset includes a single bit in the PDCP header that is set to indicate the start of a ROHC reset.

[0038] In another embodiment, the packet for indicating the start of a ROHC reset includes a PDCP control PDU configured to indicate the start of a ROHC reset.

[0039] Exemplary Systems and Apparatus

[0040] Figure 6 The architecture of a system 600 of a network according to some embodiments is shown. The system 600 is shown to include: a UE 602; a 5G access node or RAN node (shown as (R) AN node 608); a user plane function (shown as UPF 604); a data network (DN 606), which can be, for example, an operator service, Internet access, or a third-party service; and a 5G core network (5GC) (shown as CN 610).

[0041] CN 610 may include an authentication server function (AUSF 614); a core access and mobility management function (AMF 612); a session management function (SMF 618); a network exposure function (NEF 616); a policy control function (PCF 622); a network function (NF) repository function (NRF 620); a unified data management (UDM 624); and an application function (AF 626). CN 610 may also include other elements not shown, such as a structured data storage network function (SDSF), an unstructured data storage network function (UDSF), etc.

[0042] The UPF 604 may act as an anchor point for intra-RAT and inter-RAT mobility, an external PDU session point interconnected with the DN 606, and a branch point to support multi-homed PDU sessions. The UPF 604 may also perform packet routing and forwarding, packet inspection, user plane portion of policy rule enforcement, lawful interception of packets (UP collection); traffic usage reporting, QoS processing for the user plane (e.g., packet filtering, gating, UL / DL rate enforcement), uplink traffic validation (e.g., SDF to QoS flow mapping), transport level packet marking in uplink and downlink, and downlink packet buffering and downlink data notification triggering. The UPF 604 may include an uplink classifier to support routing of traffic flows to a data network. The DN 606 may represent various network operator services, Internet access, or third-party services.

[0043] AUSF 614 may store data and handle functions related to authenticating UE 602. AUSF 614 may facilitate a common authentication framework for various access types.

[0044] AMF 612 may be responsible for registration management (e.g., responsible for registering UE 602, etc.), connection management, reachability management, mobility management, and lawful interception of AMF-related events, as well as access authentication and authorization. AMF 612 may provide delivery for SM messages for SMF 618 and act as a transparent proxy for routing SM messages. AMF 612 may also provide communication between UE 602 and SMS function (SMSF) ( Figure 6 The AMF 612 may provide for transmission of short message service (SMS) messages between the AUSF 614 and the UE 602 (not shown). The AMF 612 may act as a security anchor function (SEA), which may include interaction with the AUSF 614 and the UE 602, receiving intermediate keys established as a result of the UE 602 authentication process. In the case of using USIM-based authentication, the AMF 612 may retrieve security information from the AUSF 614. The AMF 612 may also include a security content management (SCM) function that receives keys from the SEA for deriving access network-specific keys. In addition, the AMF 612 may be the termination point for the RAN CP interface (N2 reference point), the termination point for NAS (NI) signaling, and perform NAS encryption and integrity protection.

[0045] AMF 612 may also support NAS signaling with UE 602 via the N3 interworking function (IWF) interface. N3IWF may be used to provide access to untrusted entities. N3IWF may be an endpoint of the N2 and N3 interfaces for the control plane and user plane, respectively, and may therefore handle N2 signaling for PDU sessions and QoS from SMF and AMF, encapsulate / decapsulate packets for IPSec and N3 tunnels, mark N3 user plane packets in the uplink, and enforce QoS corresponding to the N3 packet marking taking into account the QoS requirements associated with such markings received via N2. N3IWF may also relay uplink and downlink control plane NAS (NI) signaling between UE 602 and AMF 612, and relay uplink and downlink user plane packets between UE 602 and UPF 604. N3IWF also provides a mechanism for establishing an IPsec tunnel with UE 602.

[0046] SMF 618 may be responsible for session management (e.g., session establishment, modification, and release, including tunnel maintenance between UPF and AN nodes); UE IP address allocation & management (including optional authorization); selection and control of UP functions; configuring traffic steering at UPF to route traffic to the correct destination; terminating the interface towards the policy control function; control part of policy enforcement and QoS; lawful interception (for SM events and interface with LI system); terminating the SM part of NAS messages; downlink data notification; initiator of AN-specific SM information sent to AN via AMF over N2; determining the SSC mode of the session. SMF 618 may include the following roaming functions: handling local execution to apply QoS SLA (VPLMN); charging data collection and charging interface (VPLMN); lawful interception (for SM events and interface with LI system, in VPLMN); supporting interaction with external DNs to transmit signaling for PDU session authorization / authentication over external DNs.

[0047] NEF 616 may provide components for securely exposing services and capabilities provided by 3GPP network functions for third parties, internal exposure / re-exposure, application functions (e.g., AF 626), edge computing or fog computing systems, etc. In such embodiments, NEF 616 may authenticate, authorize and / or restrict AF. NEF 616 may also convert information exchanged with AF 626 and information exchanged with internal network functions. For example, NEF 616 may convert between AF service identifiers and internal 5GC information. NEF 616 may also receive information from other network functions (NFs) based on their exposure capabilities. The information may be stored at NEF 616 as structured data or at a data storage NF using a standardized interface. The stored information may then be re-exposed to other NFs and AFs by NEF 616 and / or used for other purposes such as analysis.

[0048] NRF 620 may support service discovery functions, receive NF discovery requests from NF instances, and provide information of discovered NF instances to NF instances. NRF 620 also maintains information of available NF instances and services supported by these instances.

[0049] PCF 622 may provide policy rules for control plane functions to perform these functions and may also support a unified policy framework for managing network behavior. PCF 622 may also implement a front end (FE) to access subscription information related to policy decisions in the UDR of UDM 624.

[0050] The UDM 624 may process subscription-related information to support the handling of communication sessions by network entities, and may store subscription data for the UE 602. The UDM 624 may include two parts: an application FE and a user data repository (UDR). The UDM may include a UDM FE that is responsible for handling credentials, location management, subscription management, and the like. In different transactions, several different front ends may serve the same user. The UDM-FE accesses subscription information stored in the UDR and performs authentication credential processing; user identity processing; access authorization; registration / mobility management; and subscription management. The UDR may interact with the PCF 622. The UDM 624 may also support SMS management, where the SMS-FE implements similar application logic discussed previously.

[0051] AF 626 can provide the influence of applications on traffic routing, access network capability exposure (NCE), and interact with the policy framework for policy control. NCE can be a mechanism that allows 5GC and AF 626 to provide information to each other via NEF 616, which can be used for edge computing implementation. In such implementations, network operators and third-party services can be hosted near the UE 602 access point of the attachment to achieve effective service delivery through reduced end-to-end delay and load on the transmission network. For edge computing implementations, 5GC can select UPF 604 near UE 602 and perform traffic steering from UPF 604 to DN 606 via the N6 interface. This can be based on UE subscription data, UE location and information provided by AF 626. In this way, AF 626 can affect UPF (re) selection and traffic routing. Based on operator deployment, when AF 626 is considered a trusted entity, the network operator can allow AF 626 to interact directly with the relevant NF.

[0052] As discussed previously, CN 610 may include SMSF, which may be responsible for SMS subscription checking and verification, and relaying SM messages from / to other entities, such as SMS-GMSC / IWMSC / SMS routers, to / from UE 602. SMS may also interact with AMF 612 and UDM 624 for notification procedures so that UE 602 is available for SMS transmission (e.g., setting a UE unreachable flag and notifying UDM 624 when UE 602 is available for SMS).

[0053] System 600 may include the following service-based interfaces: Namf: a service-based interface presented by AMF; Nsmf: a service-based interface presented by SMF; Nnef: a service-based interface presented by NEF; Npcf: a service-based interface presented by PCF; Nudm: a service-based interface presented by UDM; Naf: a service-based interface presented by AF; Nnrf: a service-based interface presented by NRF; and Nausf: a service-based interface presented by AUSF.

[0054] System 600 may include the following reference points: N1: a reference point between UE and AMF; N2: a reference point between (R)AN and AMF; N3: a reference point between (R)AN and UPF; N4: a reference point between SMF and UPF; and N6: a reference point between UPF and data network. There may be more reference points and / or service-based interfaces between NF services in these NFs, however, these interfaces and reference points are omitted for clarity. For example, the NS reference point may be between PCF and AF; the N7 reference point may be between PCF and SMF; the N11 reference point may be between AMF and SMF; and so on. In some embodiments, CN 610 may include an Nx interface, which is an inter-CN interface between an MME (e.g., MME 928) and AMF 612 to enable intercommunication between CN 610 and CN 1106.

[0055] although Figure 6 Not shown, the system 600 may include multiple RAN nodes (such as (R)AN node 608), wherein the Xn interface is defined between two or more (R)AN nodes 608 (e.g., gNBs, etc.) connected to the 5GC 410, between a node 608 (e.g., gNB) connected to the CN 610 and an eNB, and / or between two eNBs connected to the CN 610.

[0056] In some specific implementations, the Xn interface may include an Xn user plane (Xn-U) interface and an Xn control plane (Xn-C) interface. The Xn-U may provide non-guaranteed delivery of user plane PDUs and support / provide data forwarding and flow control functions. The Xn-C may provide management and error handling functions for managing the functions of the Xn-C interface; mobility support for UE602 in connected mode (e.g., CM connection) includes the function of managing UE mobility in connected mode between one or more (R)AN nodes 608. Mobility support may include context transfer from an old (source) serving (R)AN node 608 to a new (target) serving (R)AN node 608; and control of a user plane tunnel between the old (source) serving (R)AN node 608 and the new (target) serving (R)AN node 608.

[0057] The protocol stack of Xn-U may include a transport network layer built on an Internet Protocol (IP) transport layer, and a GTP-U layer for carrying user plane PDUs on top of a UDP and / or IP layer. The Xn-C protocol stack may include an application layer signaling protocol (referred to as the Xn Application Protocol (Xn-AP)) and a transport network layer built on an SCTP layer. The SCTP layer may be located on top of the IP layer. The SCTP layer provides guaranteed delivery of application layer messages. In the transport IP layer, point-to-point transmission is used to deliver signaling PDUs. In other specific implementations, the Xn-U protocol stack and / or the Xn-C protocol stack may be the same or similar to the user plane and / or control plane protocol stacks shown and described herein.

[0058] Figure 7 Example components of a device 700 according to some embodiments are shown. In some embodiments, the device 700 may include an application circuit 702, a baseband circuit 704, a radio frequency (RF) circuit (shown as RF circuit 720), a front-end module (FEM) circuit (shown as FEM circuit 730), one or more antennas 732, and a power management circuit (PMC) (shown as PMC 734) (at least coupled together as shown). The components of the illustrated device 700 may be included in a UE or a RAN node. In some embodiments, the device 700 may include fewer elements (e.g., the RAN node cannot utilize the application circuit 702, but includes a processor / controller to process IP data received from the EPC). In some embodiments, the device 700 may include additional elements, such as a memory / storage device, a display, a camera, a sensor, or an input / output (I / O) interface. In other embodiments, the following components may be included in more than one device (e.g., the circuit may be separately included in more than one device for a cloud-RAN (C-RAN) specific implementation).

[0059] The application circuit 702 may include one or more application processors. For example, the application circuit 702 may include circuits such as, but not limited to, one or more single-core or multi-core processors. The one or more processors may include any combination of general-purpose processors and special-purpose processors (e.g., graphics processors, application processors, etc.). These processors may be coupled to or may include memory / storage devices, and may be configured to execute instructions stored in the memory / storage devices to enable various applications or operating systems to run on the device 700. In some embodiments, the processor of the application circuit 702 may process IP data packets received from the EPC.

[0060] The baseband circuit 704 may include circuits such as, but not limited to, one or more single-core or multi-core processors. The baseband circuit 704 may include one or more baseband processors or control logic components to process baseband signals received from the receive signal path of the RF circuit 720 and generate baseband signals for the transmit signal path of the RF circuit 720. The baseband circuit 704 may interact with the application circuit 702 to generate and process baseband signals and control the operation of the RF circuit 720. For example, in some embodiments, the baseband circuit 704 may include a third generation (3G) baseband processor (3G baseband processor 706), a fourth generation (4G) baseband processor (4G baseband processor 708), a fifth generation (5G) baseband processor (5G baseband processor 710), or other baseband processors 712 of other existing generations, generations under development or generations to be developed in the future (e.g., second generation (2G), sixth generation (6G), etc.). The baseband circuit 704 (e.g., one or more processors in the baseband processor) may handle various radio control functions that can communicate with one or more radio networks via the RF circuit 720. In other embodiments, some or all of the functions of the illustrated baseband processor may be included in a module stored in the memory 718 and executed via the central processing unit (CPU 714). Radio control functions may include, but are not limited to, signal modulation / demodulation, encoding / decoding, radio frequency shifting, etc. In some embodiments, the modulation / demodulation circuitry of the baseband circuitry 704 may include fast Fourier transform (FFT), precoding, or constellation mapping / demapping functions. In some embodiments, the encoding / decoding circuitry of the baseband circuitry 704 may include convolution, tail-biting convolution, turbo, Viterbi, or low-density parity check (LDPC) encoder / decoder functions. The implementation of the modulation / demodulation and encoder / decoder functions is not limited to these examples, and may include other suitable functions in other embodiments.

[0061] In some embodiments, the baseband circuit 704 may include a digital signal processor (DSP), such as one or more audio DSPs 716. The audio DSP 716 may include elements for compression / decompression and echo cancellation, and may include other suitable processing elements in other embodiments. In some embodiments, the components of the baseband circuit may be appropriately combined in a single chip, a single chipset, or disposed on the same circuit board. In some embodiments, some or all of the components of the baseband circuit 704 and the application circuit 702 may be implemented together, such as on a system on a chip (SOC).

[0062] In some embodiments, the baseband circuit 704 may provide communications compatible with one or more radio technologies. For example, in some embodiments, the baseband circuit 704 may support communications with an Evolved Universal Terrestrial Radio Access Network (EUTRAN) or other wireless metropolitan area network (WMAN), wireless local area network (WLAN), wireless personal area network (WPAN). Embodiments in which the baseband circuit 704 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuits.

[0063] The RF circuit 720 may communicate with a wireless network through a non-solid medium using modulated electromagnetic radiation. In various embodiments, the RF circuit 720 may include switches, filters, amplifiers, etc. to facilitate communication with the wireless network. The RF circuit 720 may include a receive signal path, which may include circuits for down-converting RF signals received from the FEM circuit 730 and providing baseband signals to the baseband circuit 704. The RF circuit 720 may also include a transmit signal path, which may include circuits for up-converting baseband signals provided by the baseband circuit 704 and providing an RF output signal for transmission to the FEM circuit 730.

[0064] In some embodiments, the receive signal path of the RF circuit 720 may include a mixer circuit 722, an amplifier circuit 724, and a filter circuit 726. In some embodiments, the transmit signal path of the RF circuit 720 may include a filter circuit 726 and a mixer circuit 722. The RF circuit 720 may also include a synthesizer circuit 728 for synthesizing frequencies used by the mixer circuit 722 of the receive signal path and / or the transmit signal path. In some embodiments, the mixer circuit 722 of the receive signal path may be configured to down-convert the RF signal received from the FEM circuit 730 based on the synthesized frequency provided by the synthesizer circuit 728. The amplifier circuit 724 may be configured to amplify the down-converted signal, and the filter circuit 726 may be a low pass filter (LPF) or a band pass filter (BPF) configured to remove unwanted signals from the down-converted signal to generate an output baseband signal. The output baseband signal may be provided to the baseband circuit 704 for further processing. In some embodiments, although this is not required, the output baseband signal may be a zero frequency baseband signal. In some embodiments, mixer circuit 722 of the receive signal path may include a passive mixer, although the scope of the embodiments is not limited in this respect.

[0065] In some embodiments, the mixer circuit 722 of the transmit signal path can be configured to up-convert an input baseband signal based on a synthesized frequency provided by the synthesizer circuit 728 to generate an RF output signal for the FEM circuit 730. The baseband signal can be provided by the baseband circuit 704 and can be filtered by the filter circuit 726.

[0066] In some embodiments, the mixer circuit 722 of the receive signal path and the mixer circuit 722 of the transmit signal path may include two or more mixers and may be arranged for quadrature down-conversion and up-conversion, respectively. In some embodiments, the mixer circuit 722 of the receive signal path and the mixer circuit 722 of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuit 722 of the receive signal path and the mixer circuit 722 of the transmit signal path may be arranged for direct down-conversion and direct up-conversion, respectively. In some embodiments, the mixer circuit 722 of the receive signal path and the mixer circuit 722 of the transmit signal path may be configured for superheterodyne operation.

[0067] In some embodiments, the output baseband signal and the input baseband signal may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternative embodiments, the output baseband signal and the input baseband signal may be digital baseband signals. In these alternative embodiments, the RF circuit 720 may include an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC) circuit, and the baseband circuit 704 may include a digital baseband interface to communicate with the RF circuit 720.

[0068] In some dual-mode embodiments, separate radio IC circuits may be provided to process signals for each spectrum, although the scope of the embodiments is not limited in this respect.

[0069] In some embodiments, synthesizer circuit 728 may be a fractional-N synthesizer or a fractional N / N+1 synthesizer, but the scope of the embodiments is not limited in this regard, as other types of frequency synthesizers may also be suitable. For example, synthesizer circuit 728 may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer including a phase-locked loop with a frequency divider.

[0070] The synthesizer circuit 728 may be configured to synthesize an output frequency based on the frequency input and the divider control input for use by the mixer circuit 722 of the RF circuit 720. In some embodiments, the synthesizer circuit 728 may be a fractional-N / N+1 synthesizer.

[0071] In some embodiments, the frequency input may be provided by a voltage controlled oscillator (VCO), although this is not required. The divider control input may be provided by baseband circuitry 704 or application circuitry 702 (such as an application processor) according to the desired output frequency. In some embodiments, the divider control input (e.g., N) may be determined from a lookup table based on the channel indicated by application circuitry 702.

[0072] The synthesizer circuit 728 of the RF circuit 720 may include a frequency divider, a delay locked loop (DLL), a multiplexer, and a phase accumulator. In some embodiments, the frequency divider may be a dual-mode frequency divider (DMD), and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by N or N+1 (e.g., based on carry) to provide a fractional division ratio. In some example embodiments, the DLL may include a cascaded, tunable, delay element, a phase detector, a charge pump, and a D-type flip-flop set. In these embodiments, the delay element may be configured to divide the VCO cycle into Nd equal phase groups, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[0073] In some embodiments, the synthesizer circuit 728 can be configured to generate a carrier frequency as an output frequency, while in other embodiments, the output frequency can be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and can be used with a quadrature generator and divider circuit to generate multiple signals with multiple different phases relative to each other at the carrier frequency. In some embodiments, the output frequency can be the LO frequency (fLO). In some embodiments, the RF circuit 720 can include an IQ / polarity converter.

[0074] The FEM circuitry 730 may include a receive signal path that may include circuitry configured to operate on RF signals received from one or more antennas 732, amplify the receive signal, and provide an amplified version of the receive signal to the RF circuitry 720 for further processing. The FEM circuitry 730 may also include a transmit signal path that may include circuitry configured to amplify transmit signals provided by the RF circuitry 720 for transmission by one or more of the one or more antennas 732. In various embodiments, amplification by either the transmit signal path or the receive signal path may be accomplished only in the RF circuitry 720, only in the FEM circuitry 730, or in both the RF circuitry 720 and the FEM circuitry 730.

[0075] In some embodiments, the FEM circuit 730 may include a TX / RX switch to switch between transmit mode and receive mode operation. The FEM circuit 730 may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuit 730 may include an LNA to amplify the received RF signal and provide the amplified received RF signal as an output (e.g., to the RF circuit 720). The transmit signal path of the FEM circuit 730 may include a power amplifier (PA) to amplify the input RF signal (e.g., provided by the RF circuit 720), and one or more filters to generate an RF signal for subsequent transmission (e.g., through one or more of the one or more antennas 732).

[0076] In some embodiments, the PMC 734 can manage the power provided to the baseband circuit 704. Specifically, the PMC 734 can control power selection, voltage scaling, battery charging, or DC-DC conversion. When the device 700 is capable of being powered by a battery, for example, when the device 700 is included in a UE, the PMC 734 can generally be included. The PMC 734 can improve power conversion efficiency while providing the desired specific implementation size and heat dissipation characteristics.

[0077] Figure 7 PMC 734 is shown coupled only to baseband circuitry 704. However, in other embodiments, PMC 734 may additionally or alternatively be coupled to other components (such as, but not limited to, application circuitry 702, RF circuitry 720, or FEM circuitry 730) and perform similar power management operations for these components.

[0078] In some embodiments, the PMC 734 may control or otherwise be part of various power saving mechanisms of the device 700. For example, if the device 700 is in the RRC_Connected state, where the device is still connected to the RAN node because it expects to receive traffic immediately, then after a period of inactivity, the device may enter a state known as discontinuous reception mode (DRX). During this state, the device 700 may be powered off for short time intervals, thereby saving power.

[0079] If there is no data traffic activity for an extended period of time, the device 700 may transition to the RRC_Idle state, in which the device is disconnected from the network and does not perform operations such as channel quality feedback, handover, etc. The device 700 enters a very low power state and performs paging, in which the device periodically wakes up again to listen to the network and then powers down again. The device 700 cannot receive data in this state, and in order to receive data, the device must transition back to the RRC_Connected state.

[0080] An additional power saving mode can keep a device from using the network for longer than the paging interval (which can range from a few seconds to several hours). During this time, the device is completely unable to connect to the network and can be completely powered down. Any data sent during this time will be significantly delayed, and it is assumed that the delay is acceptable.

[0081] The processor of the application circuit 702 and the processor of the baseband circuit 704 can be used to execute elements of one or more instances of the protocol stack. For example, the processor of the baseband circuit 704 can be used alone or in combination to perform layer 3, layer 2, or layer 1 functions, while the processor of the application circuit 702 can utilize data received from these layers (e.g., packet data) and further perform layer 4 functions (e.g., transport communication protocol (TCP) and user datagram protocol (UDP) layers). As mentioned herein, layer 3 may include a radio resource control (RRC) layer, which will be described in further detail below. As mentioned herein, layer 2 may include a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer, which will be described in further detail below. As mentioned herein, layer 1 may include a physical (PHY) layer of a UE / RAN node, which will be described in further detail below.

[0082] Figure 8 An exemplary interface 800 of a baseband circuit according to some embodiments is shown. As described above, Figure 7 The baseband circuit 704 may include a 3G baseband processor 706, a 4G baseband processor 708, a 5G baseband processor 710, other baseband processors 712, a CPU 714, and a memory 718 for use by the processors. As shown, each of the processors may include a corresponding memory interface 802 for sending / receiving data to / from the memory 718.

[0083] The baseband circuit 704 may also include one or more interfaces to communicatively couple to other circuits / devices, such as a memory interface 804 (e.g., an interface for sending / receiving data to / from a memory external to the baseband circuit 704), an application circuit interface 806 (e.g., an interface for sending / receiving data to / from a memory external to the baseband circuit 704), and an application circuit interface 807 (e.g., an interface for sending / receiving data to / from a memory external to the baseband circuit 704). Figure 7 The application circuit 702 sends / receives data), the RF circuit interface 808 (for example, for sending / receiving data to / from the application circuit 702), Figure 7 an interface for sending / receiving data to / from a RF circuit 720), a wireless hardware connection interface 810 (e.g., for sending / receiving data to / from a near field communication (NFC) component, Parts (e.g. Low Energy), components and other communication components to send / receive data) and a power management interface 812 (for example, an interface for sending / receiving power or control signals to / from PMC 734).

[0084] Fig. 9 900 is an illustration of a control plane protocol stack according to some embodiments. In this embodiment, the control plane 900 is shown as a communication protocol stack between UE 902, RAN 908 and MME 928.

[0085] The PHY layer 904 may transmit or receive information used by the MAC layer 906 over one or more air interfaces. The PHY layer 904 may also perform link adaptation or adaptive modulation and coding (AMC), power control, cell search (e.g., for initial synchronization and handover purposes), and other measurements used by higher layers such as the RRC layer 914. The PHY layer 904 may still perform: error detection on transport channels, forward error correction (FEC) encoding / decoding of transport channels, modulation / demodulation of physical channels, interleaving, rate matching, mapping to physical channels, and multiple-input multiple-output (MIMO) antenna processing.

[0086] The MAC layer 906 can perform: mapping between logical channels and transport channels, multiplexing MAC service data units (SDUs) from one or more logical channels onto transport blocks (TBs) to be delivered to PHY via transport channels, demultiplexing MAC SDUs from transport blocks (TBs) delivered from PHY via transport channels to one or more logical channels, multiplexing MAC SDUs onto TBs, scheduling information reporting, error correction through hybrid automatic repeat request (HARQ), and logical channel prioritization.

[0087] The RLC layer 910 can operate in multiple operation modes, including: transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM). The RLC layer 910 can perform: transmission of upper layer protocol data units (PDUs), error correction through automatic repeat request (ARQ) for AM data transmission, and concatenation, segmentation, and reassembly of RLC SDUs for UM and AM data transmission. The RLC layer 910 can also perform re-segmentation of RLC data PDUs for AM data transmission, reordering of RLC data PDUs for UM and AM data transmission, detection of duplicate data for UM and AM data transmission, discarding RLC SDUs for UM and AM data transmission, detecting protocol errors for AM data transmission, and performing RLC re-establishment.

[0088] The PDCP layer 912 can perform header compression and decompression of IP data, maintain the PDCP sequence number (SN), perform in-sequence delivery of upper layer PDUs when the lower layer is re-established, eliminate duplication of lower layer SDUs when the lower layer is re-established for the radio bearer mapped on RLC AM, encrypt and decrypt control plane data, perform integrity protection and integrity verification on control plane data, control timer-based data discard, and perform security operations (e.g., encryption, decryption, integrity protection, integrity verification, etc.).

[0089] The main services and functions of the RRC layer 914 may include broadcasting of system information (e.g., included in a master information block (MIB) or a system information block (SIB) related to a non-access stratum (NAS)), broadcasting of system information related to an access stratum (AS), paging, establishment, maintenance, and release of an RRC connection between a UE and an E-UTRAN (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), establishment, configuration, maintenance, and release of point-to-point radio bearers, security functions including key management, mobility between radio access technologies (RATs), and measurement configuration for UE measurement reporting. The MIB and SIB may include one or more information elements (IEs), each of which may include a separate data field or data structure.

[0090] The UE 902 and the RAN 908 may utilize a Uu interface (eg, an LTE-Uu interface) to exchange control plane data via a protocol stack including a PHY layer 904 , a MAC layer 906 , an RLC layer 910 , a PDCP layer 912 , and an RRC layer 914 .

[0091] In the illustrated embodiment, the non-access stratum (NAS) protocol (NAS protocol 916) forms the highest layer of the control plane between the UE 902 and the MME 928. The NAS protocol 916 supports the mobility and session management procedures of the UE 902 to establish and maintain the IP connection between the UE 902 and the P-GW 1008.

[0092] The S1 application protocol (S1-AP) layer (S1-AP layer 926) may support the functions of the S1 interface and include an elementary procedure (EP). The EP is an interaction unit between the RAN 908 and the CN 1106. The S1-AP layer services may include two groups: UE-associated services and non-UE-associated services. The functions performed by these services include, but are not limited to: E-UTRAN Radio Access Bearer (E-RAB) management, UE capability indication, mobility, NAS signaling transmission, RAN Information Management (RIM), and configuration transmission.

[0093] The stream control transmission protocol (SCTP) layer (alternatively referred to as the stream control transmission protocol / Internet protocol (SCTP / IP) layer) (SCTP layer 924) may ensure reliable delivery of signaling messages between the RAN 908 and the MME 928 based in part on the IP protocol supported by the IP layer 922. The L2 layer 920 and the L1 layer 918 may refer to communication links (e.g., wired or wireless) used by the RAN nodes and the MME to exchange information.

[0094] The RAN 908 and the MME 928 may exchange control plane data via a protocol stack including the L1 layer 918 , the L2 layer 920 , the IP layer 922 , the SCTP layer 924 , and the S1-AP layer 926 using an S1-MME interface.

[0095] Fig.10 1000 is an illustration of a user plane protocol stack according to some embodiments. In this embodiment, the user plane 1000 is shown as a communication protocol stack between the UE 902, the RAN 908, the S-GW 1006, and the P-GW 1008. The user plane 1000 may utilize at least some of the same protocol layers as the control plane 900. For example, the UE 902 and the RAN 908 may utilize a Uu interface (e.g., an LTE-Uu interface) to exchange user plane data via a protocol stack including a PHY layer 904, a MAC layer 906, an RLC layer 910, and a PDCP layer 912.

[0096] The General Packet Radio Service (GPRS) Tunneling Protocol for User Plane (GTP-U) layer (GTP-U layer 1004) may be used to carry user data within the GPRS core network and between the radio access network and the core network. For example, the transmitted user data may be packets in any of the IPv4, IPv6, or PPP formats. The UDP and IP Security (UDP / IP) layer (UDP / IP layer 1002) may provide checksums for data integrity, port numbers for addressing different functions at the source and destination, and encryption and authentication of selected data flows. The RAN 908 and the S-GW 1006 may exchange user plane data via a protocol stack including the L1 layer 918, the L2 layer 920, the UDP / IP layer 1002, and the GTP-U layer 1004 using the S1-U interface. S-GW 1006 and P-GW 1008 may utilize an S5 / S8a interface to exchange user plane data via a protocol stack including L1 layer 918, L2 layer 920, UDP / IP layer 1002, and GTP-U layer 1004. Fig. 9 As discussed, the NAS protocol supports the mobility and session management procedures of UE 902 to establish and maintain an IP connection between UE 902 and P-GW 1008.

[0097] Fig.11 Components 1100 of a core network according to some embodiments are shown. Components of CN 1106 may be implemented in one physical node or separate physical nodes, including components for reading and executing instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium). In some embodiments, network function virtualization (NFV) is used to virtualize any or all of the above-mentioned network node functions via executable instructions stored in one or more computer-readable storage media (described in further detail below). A logical instance of CN 1106 may be referred to as a network slice 1102 (e.g., network slice 1102 is shown to include HSS 1108, MME 928, and S-GW 1006). A logical instance of a portion of CN 1106 may be referred to as a network sub-slice 1104 (e.g., network sub-slice 1104 is shown to include P-GW 1008 and PCRF 1110).

[0098] NFV architecture and infrastructure can be used to virtualize one or more network functions onto physical resources including a combination of industry-standard server hardware, storage hardware, or switches (alternatively performed by proprietary hardware). In other words, the NFV system can be used to perform a virtual or reconfigurable implementation of one or more EPC components / functions.

[0099] Fig.12 1 is a block diagram illustrating components of a NFV-enabled system 1200 according to some example embodiments. The system 1200 is illustrated as including a virtualization infrastructure manager (illustrated as VIM 1202), a network function virtualization infrastructure (illustrated as NFVI 1204), a VNF manager (illustrated as VNFM 1206), virtualized network functions (illustrated as VNF 1208), an element manager (illustrated as EM 1210), a NFV orchestrator (illustrated as NFVO 1212), and a network manager (illustrated as NM 1214).

[0100] The VIM 1202 manages resources of the NFVI 1204. The NFVI 1204 may include physical or virtual resources and applications (including a hypervisor) for executing the system 1200. The VIM 1202 may utilize the NFVI 1204 to manage the lifecycle of virtual resources (e.g., creation, maintenance, and teardown of virtual machines (VMs) associated with one or more physical resources), track VM instances, track performance, failures, and security of VM instances and associated physical resources, and expose VM instances and associated physical resources to other management systems.

[0101] The VNFM 1206 may manage the VNF 1208. The VNF 1208 may be used to perform EPC components / functions. The VNFM 1206 may manage the lifecycle of the VNF 1208 and track the performance, failures, and security of the VNF 1208 in virtual terms. The EM 1210 may track the performance, failures, and security of the VNF 1208 in functional terms. The tracking data from the VNFM 1206 and the EM 1210 may include, for example, performance measurement (PM) data used by the VIM 1202 or the NFVI 1204. The VNFM 1206 and the EM 1210 may both scale up / down the number of VNFs of the system 1200.

[0102] NFVO 1212 may coordinate, authorize, release, and engage resources of NFVI 1204 in order to provide requested services (e.g., to execute EPC functions, components, or slices). NM 1214 may provide an end-user functional package responsible for network management, which may include network elements with VNFs, non-virtualized network functions, or both (management of VNFs may occur via EM 1210).

[0103] Fig.13 1 is a block diagram illustrating a component 1300 capable of reading instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium) and capable of performing any one or more of the methods discussed herein, according to some exemplary embodiments. Specifically, Fig.13 A schematic diagram of hardware resources 1302 is shown, which includes one or more processors 1312 (or processor cores), one or more memory / storage devices 1318, and one or more communication resources 1320, each of which can be communicatively coupled via a bus 1322. For embodiments in which node virtualization (e.g., NFV) is utilized, a hypervisor 1304 can be executed to provide an execution environment for one or more network slices / sub-slices to utilize the hardware resources 1302.

[0104] Processor 1312 (e.g., a central processing unit (CPU), a reduced instruction set computing (RISC) processor, a complex instruction set computing (CISC) processor, a graphics processing unit (GPU), a digital signal processor (DSP) (such as a baseband processor), an application specific integrated circuit (ASIC), a radio frequency integrated circuit (RFIC), another processor, or any suitable combination thereof) may include, for example, processor 1314 and processor 1316.

[0105] The memory / storage device 1318 may include main memory, disk storage, or any suitable combination thereof. The memory / storage device 1318 may include, but is not limited to, any type of volatile or non-volatile memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, solid-state storage, etc.

[0106] The communication resources 1320 may include interconnect or network interface components or other suitable devices to communicate with one or more peripheral devices 1306 or one or more databases 1308 via the network 1310. For example, the communication resources 1320 may include a wired communication component (e.g., for coupling via a universal serial bus (USB)), a cellular communication component, an NFC component, Parts (e.g. Low power consumption), components and other communication components.

[0107] The instructions 1324 may include software, programs, applications, applet, applications, or other executable code for causing at least any one of the processors 1312 to perform any one or more of the methods discussed herein. The instructions 1324 may reside completely or partially in at least one of the processors 1312 (e.g., within a cache memory of the processor), the memory / storage device 1318, or any suitable combination thereof. In addition, any portion of the instructions 1324 may be transferred to the hardware resources 1302 from any combination of the peripheral device 1306 or the database 1308. Thus, the memory of the processor 1312, the memory / storage device 1318, the peripheral device 1306, and the database 1308 are examples of computer-readable and machine-readable media.

[0108] For one or more embodiments, at least one of the components shown in one or more of the foregoing figures may be configured to perform one or more operations, techniques, processes and / or methods described in the following examples section. For example, the baseband circuit described above in conjunction with one or more of the foregoing figures may be configured to operate according to one or more of the following embodiments. For another example, the circuits associated with the UE, base station, network element, etc. described above in conjunction with one or more of the foregoing figures may be configured to operate according to one or more of the embodiments shown in the examples section below.

[0109] Examples

[0110] The following examples relate to additional embodiments.

[0111] Embodiment 1 is a device for user equipment (UE), the user equipment (UE) being configured to perform a handover from a source cell to a target cell in a wireless network. The device includes a memory interface and a processor. The memory interface is used to send or receive packets received from the source cell and the target cell to or from the memory device. The processor is used to: perform packet data convergence protocol (PDCP) decryption of the packets to store the decrypted packets in a common buffer; perform PDCP reordering on the decrypted packets in the common buffer to generate a reordered packet stream; perform robust header compression (ROHC) decompression on the reordered packet stream; and reset the ROHC decompression based on a packet indication determination.

[0112] Embodiment 2 includes the apparatus of embodiment 1, wherein the packet indication comprises a single bit in a PDCP header, the single bit being set to indicate the start of a ROHC reset based on a path transition during the handover from the source cell to the target cell.

[0113] Embodiment 3 includes the apparatus of embodiment 2, wherein the PDCP header corresponds to a PDCP data protocol data unit (PDU) carrying data from a data radio bearer (DRB).

[0114] Embodiment 4 includes the apparatus of embodiment 3, wherein the PDCP data PDU corresponds to one of the packets received from the target cell.

[0115] Embodiment 5 includes the apparatus of embodiment 1, wherein the packet indication comprises a PDCP control protocol data unit (PDU) configured to indicate the start of a ROHC reset.

[0116] Embodiment 6 includes an apparatus according to embodiment 5, wherein the processor is further configured to simultaneously perform physical (PHY) layer processing, medium access control (MAC) layer processing, and radio link control (RLC) layer processing on both a first set of packets received from the source cell and a second set of packets received from the target cell.

[0117] Embodiment 7 includes the apparatus of embodiment 6, wherein the processor is further configured to perform an integrity protection check on control plane packets received from at least one of the source cell and the target cell.

[0118] Embodiment 8 is a non-transitory computer-readable storage medium. The computer-readable storage medium includes instructions that, when executed by a processor of a user equipment, cause the processor to: process packets received from a source cell and a target cell; perform Packet Data Convergence Protocol (PDCP) decryption of the packets to store the decrypted packets in a common buffer; perform PDCP reordering on the decrypted packets in the common buffer to generate a reordered packet stream; perform Robust Header Compression (ROHC) decompression on the reordered packet stream; and reset the ROHC decompression based on a packet indication determination.

[0119] Embodiment 9 includes the computer-readable storage medium of embodiment 8, wherein the packet indication comprises a single bit in a PDCP header, the single bit being set to indicate the start of a ROHC reset based on a path transition during the handover from the source cell to the target cell.

[0120] Embodiment 10 includes the computer-readable storage medium of embodiment 9, wherein the PDCP header corresponds to a PDCP data protocol data unit (PDU) carrying data from a data radio bearer (DRB).

[0121] Embodiment 11 includes the computer-readable storage medium of embodiment 10, wherein the PDCP data PDU corresponds to one of the packets received from the target cell.

[0122] Embodiment 12 includes the computer-readable storage medium of embodiment 8, wherein the packet indication includes a PDCP control protocol data unit (PDU) configured to indicate the start of a ROHC reset.

[0123] Embodiment 13 includes a computer-readable storage medium according to embodiment 12, wherein processing the packets received from the source cell and the target cell includes simultaneously performing physical (PHY) layer processing, medium access control (MAC) layer processing, and radio link control (RLC) layer processing on both a first set of packets received from the source cell and a second set of packets received from the target cell.

[0124] Embodiment 14 includes the computer-readable storage medium of embodiment 13, wherein the instructions further configure the processor to perform an integrity protection check on control plane packets received from at least one of the source cell and the target cell.

[0125] Embodiment 15 is a non-transitory computer-readable storage medium. The computer-readable storage medium includes instructions, which, when executed by a processor of a target cell in a wireless communication system, cause the processor to: receive a portion of a packet data convergence protocol (PDCP) protocol data unit (PDU) from a source cell in the wireless communication system, the portion of the PDCP PDU including robust header compression (ROHC) performed by the source cell; perform PDCP encryption on the portion of the PDCP PDU to generate an encrypted PDCP PDU; and send the encrypted PDCP PDU to a user equipment (UE). After releasing the source cell to complete the path transition to the target cell, the instructions cause the processor to: perform ROHC on data received from a core network of the wireless communication system; and generate a packet to indicate the start of a ROHC reset to the UE.

[0126] Embodiment 16 includes the computer-readable storage medium of embodiment 15, wherein the packet for indicating the start of the ROHC reset comprises a single bit in a PDCP header, the single bit being set to indicate the start of the ROHC reset.

[0127] Embodiment 17 includes the computer-readable storage medium of embodiment 15, wherein the packet for indicating the start of the ROHC reset comprises a PDCP control PDU configured to indicate the start of the ROHC reset.

[0128] Embodiment 18 includes the computer-readable storage medium of embodiment 17, wherein the instructions further configure the processor to perform integrity protection on control plane data of the partial PDCP PDU.

[0129] Embodiment 19 is a method for handover of a user equipment (UE) in a wireless communication system for a target cell. The method includes: receiving a portion of a packet data convergence protocol (PDCP) protocol data unit (PDU) from a source cell in the wireless communication system, the portion of the PDCP PDU including robust header compression (ROHC) performed by the source cell; performing PDCP encryption on the portion of the PDCP PDU to generate an encrypted PDCP PDU; and sending the encrypted PDCP PDU to the UE. After releasing the source cell to complete the path transition to the target cell, the method also includes: performing ROHC on data received from a core network of the wireless communication system; and generating a packet to indicate the start of a ROHC reset to the UE.

[0130] Embodiment 20 includes the method of embodiment 19, wherein the packet used to indicate the start of the ROHC reset comprises a single bit in a PDCP header, the single bit being set to indicate the start of the ROHC reset.

[0131] Embodiment 21 includes the method of embodiment 19, wherein the packet for indicating the start of the ROHC reset comprises a PDCP control PDU configured to indicate the start of the ROHC reset.

[0132] Embodiment 22 includes the method according to embodiment 21, further comprising performing integrity protection on control plane data of the partial PDCP PDU.

[0133] Unless explicitly stated otherwise, any of the above embodiments may be combined with any other embodiment (or combination of embodiments). The foregoing description of one or more specific implementations provides illustration and description, but is not intended to be exhaustive or to limit the scope of the embodiments to the precise form disclosed. Modifications and variations are possible in view of the above teachings or may be obtained from the practice of the various embodiments.

[0134] Embodiments and implementations of the systems and methods described herein may include various operations that may be embodied in machine executable instructions to be executed by a computer system. A computer system may include one or more general or special purpose computers (or other electronic devices). A computer system may include hardware components that include specific logic components for performing operations, or may include a combination of hardware, software, and / or firmware.

[0135] It should be appreciated that the systems described herein include descriptions of specific embodiments. These embodiments may be combined into a single system, partially incorporated into other systems, separated into multiple systems, or otherwise divided or combined. In addition, it is contemplated that parameters / attributes / aspects, etc. of one embodiment may be used in another embodiment. For clarity, these parameters / attributes / aspects, etc. are described only in one or more embodiments, and it should be appreciated that unless otherwise stated herein, these parameters / attributes / aspects, etc. may be combined with or substituted for parameters / attributes, etc. of another embodiment.

[0136] Although the foregoing has been described in considerable detail for the sake of clarity, it will be apparent that certain changes and modifications may be made without departing from the principles of the invention. It should be noted that there are many alternative ways to implement both the processes and the apparatus described herein. Therefore, the embodiments of the present invention are to be regarded as illustrative rather than restrictive, and the specification is not limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.

Claims

1. An apparatus for a user equipment UE, the apparatus being configured to perform a handover from a source cell to a target cell in a wireless network, the apparatus comprising: a memory interface, the memory interface being used to send packets received from the source cell and the target cell to or from a memory device; and A processor, the processor being configured to: performing Packet Data Convergence Protocol (PDCP) decryption of the packets to store the decrypted packets in a common buffer; performing PDCP reordering on the decrypted packets in the common buffer to generate a reordered packet stream; performing robust header compression (ROHC) decompression on the reordered packet stream; as well as Determining to reset the ROHC decompression is based on a packet indication, wherein the packet indication comprises a single bit in a PDCP header, the single bit being set to indicate the start of a ROHC reset based on a path transition during a handover from the source cell to the target cell. 2 . The apparatus of claim 1 , wherein the PDCP header corresponds to a PDCP data protocol data unit (PDU) carrying data from a data radio bearer (DRB). 3 . The apparatus of claim 2 , wherein the PDCP data protocol data unit (PDU) corresponds to one of the packets received from the target cell. 4 . The apparatus of claim 1 , wherein the packet indication comprises a PDCP control protocol data unit (PDU) configured to indicate a start of a ROHC reset.

5. The apparatus according to claim 4, wherein the processor is further configured to: simultaneously perform physical (PHY) layer processing, medium access control (MAC) layer processing, and radio link control (RLC) layer processing on both the first packet set received from the source cell and the second packet set received from the target cell.

6. The apparatus of claim 5, wherein the processor is further configured to perform an integrity protection check on control plane packets received from at least one of the source cell and the target cell.

7. A non-transitory computer-readable storage medium comprising instructions that, when executed by a processor of user equipment, cause the processor to: Processing packets received from source and target cells; performing Packet Data Convergence Protocol (PDCP) decryption of the packets to store the decrypted packets in a common buffer; performing PDCP reordering on the decrypted packets in the common buffer to generate a reordered packet stream; performing robust header compression (ROHC) decompression on the reordered packet stream; as well as Determining to reset the ROHC decompression is based on a packet indication, wherein the packet indication comprises a single bit in a PDCP header, the single bit being set to indicate the start of a ROHC reset based on a path transition during a handover from the source cell to the target cell.

8. The computer-readable storage medium of claim 7, wherein the PDCP header corresponds to a PDCP data protocol data unit (PDU) carrying data from a data radio bearer (DRB).

9. The computer-readable storage medium of claim 8, wherein the PDCP data protocol data unit (PDU) corresponds to one of the packets received from the target cell.

10. The computer-readable storage medium of claim 7, wherein the packet indication comprises a PDCP control protocol data unit (PDU) configured to indicate the start of a ROHC reset.

11. The computer-readable storage medium of claim 10, wherein processing the packets received from the source cell and the target cell comprises: Physical (PHY) layer processing, medium access control (MAC) layer processing, and radio link control (RLC) layer processing are simultaneously performed on both a first set of packets received from the source cell and a second set of packets received from the target cell.

12. The computer-readable storage medium of claim 11, wherein the instructions further configure the processor to perform an integrity protection check on control plane packets received from at least one of the source cell and the target cell.

13. A non-transitory computer-readable storage medium comprising instructions that, when executed by a processor of a target cell in a wireless communication system, cause the processor to: receiving a portion of a packet data convergence protocol (PDCP) protocol data unit (PDU) from a source cell in the wireless communication system, wherein the portion of the PDCP PDU includes a robust header compression (ROHC) performed by the source cell; performing PDCP ciphering on the partial PDCP PDU to generate a ciphered PDCP PDU; Sending the encrypted PDCP PDU to a user equipment UE; as well as After releasing the source cell to complete the path transition to the target cell: performing ROHC on data received from a core network of the wireless communication system; and A packet is generated for indicating a start of a ROHC reset to the UE, wherein the packet for indicating the start of the ROHC reset comprises a single bit in a PDCP header that is set to indicate the start of the ROHC reset.

14. The computer-readable storage medium of claim 13, wherein the packet for indicating the start of the ROHC reset comprises a PDCP control PDU configured to indicate the start of the ROHC reset.

15. The computer-readable storage medium of claim 14, wherein the instructions further configure the processor to perform integrity protection on control plane data of the partial PDCP PDU.

16. A method for a target cell for handover of a user equipment UE in a wireless communication system, the method comprising: receiving a portion of a packet data convergence protocol (PDCP) protocol data unit (PDU) from a source cell in the wireless communication system, wherein the portion of the PDCP PDU includes a robust header compression (ROHC) performed by the source cell; performing PDCP ciphering on the partial PDCP PDU to generate a ciphered PDCP PDU; sending the encrypted PDCP PDU to the UE; as well as After releasing the source cell to complete the path transition to the target cell: performing ROHC on data received from a core network of the wireless communication system; and A packet is generated for indicating a start of a ROHC reset to the UE, wherein the packet for indicating the start of the ROHC reset comprises a single bit in a PDCP header that is set to indicate the start of the ROHC reset.

17. The method of claim 16, wherein the packet for indicating the start of the ROHC reset comprises a PDCP control PDU configured to indicate the start of the ROHC reset.

18. The method of claim 17, further comprising performing integrity protection on control plane data of the partial PDCP PDU.

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