WO2021223054A1

WO2021223054A1 - Data stall recovery

Info

Publication number: WO2021223054A1
Application number: PCT/CN2020/088578
Authority: WO
Inventors: Hao Zhang; Fojian ZHANG; Chaofeng HUI; Jian Li
Original assignee: Qualcomm Incorporated
Priority date: 2020-05-05
Filing date: 2020-05-05
Publication date: 2021-11-11

Abstract

Certain aspects of the present disclosure provide techniques for recovering from a data stall. A method that may be performed by a user equipment (UE) includes obtaining a first packet and a second packet from a network entity, determining that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold, and performing a deregistration procedure and a registration procedure for mobility management at the network entity based on the determination.

Description

DATA STALL RECOVERY

BACKGROUND

Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for recovering from a data stall.

Description of Related Art

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc. ) . Examples of such multiple-access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE Advanced (LTE-A) systems, 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, to name a few.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. New radio (e.g., 5G NR) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL) . To these ends, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in NR and LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

SUMMARY

The systems, methods, and devices of the disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this disclosure as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of this disclosure provide advantages that include recovering from and/or preventing a stall in downlink data.

Certain aspects of the subject matter described in this disclosure can be implemented in a method for wireless communications. The method generally includes obtaining a first packet and a second packet from a network entity, determining that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold, and performing a deregistration procedure and a registration procedure for mobility management at the network entity based on the determination.

Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communications. The apparatus generally includes means for obtaining a first packet and a second packet from a network entity, means for determining that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold, and means for performing a deregistration procedure and a registration procedure for mobility management at the network entity based on the determination.

Certain aspects of the subject matter described in this disclosure can be implemented in an apparatus for wireless communications. The apparatus generally includes a processing system configured to obtain a first packet and a second packet from a network entity, determine that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold, and perform a deregistration procedure and a registration procedure for mobility management at the network entity based on the determination.

Certain aspects of the subject matter described in this disclosure can be implemented in an user equipment (UE) . The UE generally includes a receiver configured to receive a first packet and a second packet from a network entity and a processing system configured to determine that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold and perform a deregistration procedure and a registration procedure for mobility management at the network entity based on the determination.

Certain aspects of the subject matter described in this disclosure can be implemented in a computer-readable medium for wireless communications. The computer-readable medium generally includes instruction executable to obtain a first packet and a second packet from a network entity, determine that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold, and perform a deregistration procedure and a registration procedure for mobility management at the network entity based on the determination.

Aspects of the present disclosure provide means for, apparatus, processors, and computer-readable mediums for performing the methods described herein.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the appended drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

FIG. 1 is a block diagram conceptually illustrating an example wireless communication network, in accordance with certain aspects of the present disclosure.

FIG. 2 is a block diagram conceptually illustrating a design of an example a base station (BS) and user equipment (UE) , in accordance with certain aspects of the present disclosure.

FIG. 3A is a block diagram illustrating an example communication protocol stack for a user plane, in accordance with certain aspects of the present disclosure.

FIG. 3B is a block diagram illustrating an example communication protocol stack for a control plane, in accordance with certain aspects of the present disclosure.

FIG. 4 is a signaling flow diagram illustrating example operations to recover and/or prevent a stall in downlink data, in accordance with certain aspects of the present disclosure.

FIG. 5 is a flow diagram illustrating example operations for wireless communication by a UE, in accordance with certain aspects of the present disclosure.

FIG. 6 illustrates a wireless communication device (e.g., a UE) that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure.

The attached APPENDIX includes details of certain aspects of the present disclosure.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for recovering or preventing a stall in downlink data. In aspects, the UE may monitor Packet Data Convergence Protocol (PDCP) packets from the BS, and if there is a jump in the PDCP sequence number relative to a certain threshold, the UE may reestablish the NAS session (e.g., a mobility management session) with the core network. For example, if the difference between the sequence numbers of PDCP packets received at the UE is greater than or equal to a threshold, the UE may perform a deregistration procedure and a registration procedure for mobility management (e.g., at a NAS layer) at a network entity (e.g., the RAN and/or core network) .

The following description provides examples of recovering and/or preventing a stall in downlink data in communication systems, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim. 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 advantageous over other aspects.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, etc. A frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, a subband, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs.

The techniques described herein may be used for various wireless networks and radio technologies. While aspects may be described herein using terminology commonly associated with Third Generation (3G) , Fourth Generation (4G) , and/or new radio (e.g., Fifth Generation (5G) NR) wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems.

NR access may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz or beyond) , millimeter wave (mmW) targeting high carrier frequency (e.g., e.g., 24 GHz to 53 GHz or beyond) , massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC) . These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe. NR supports beamforming and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. Multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.

FIG. 1 illustrates an example wireless communication network 100 in which aspects of the present disclosure may be performed. For example, the wireless communication network 100 may be an NR system (e.g., a 5G NR network) . As shown, the UE 120a includes a packet manager 122 that monitors the sequence numbers (SNs) of certain packets (e.g., PDCP packets) and resets a Non-Access Stratum (NAS) session with the core network 132 if there is a jump in the SNs between consecutively received packets above or at a certain threshold, in accordance with aspects of the present disclosure.

As illustrated in FIG. 1, the wireless communication network 100 may include a number of BSs 110a-z (each also individually referred to herein as BS 110 or collectively as BSs 110) and other network entities. A BS 110 may provide communication coverage for a particular geographic area, sometimes referred to as a “cell” , which may be stationary or may move according to the location of a mobile BS 110. In some examples, the BSs 110 may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in wireless communication network 100 through various types of backhaul interfaces (e.g., a direct physical connection, a wireless connection, a virtual network, or the like) using any suitable transport network. In the example shown in FIG. 1, the

BSs

110a, 110b and 110c may be macro BSs for the

macro cells

102a, 102b and 102c, respectively. The BS 110x may be a pico BS for a pico cell 102x. The BSs 110y and 110z may be femto BSs for the

femto cells

102y and 102z, respectively. A BS may support one or multiple cells.

The BSs 110 communicate with UEs 120a-y (each also individually referred to herein as UE 120 or collectively as UEs 120) in the wireless communication network 100. The UEs 120 (e.g., 120x, 120y, etc. ) may be dispersed throughout the wireless communication network 100, and each UE 120 may be stationary or mobile. Wireless communication network 100 may also include relay stations (e.g., relay station 110r) , also referred to as relays or the like, that receive a transmission of data and/or other information from an upstream station (e.g., a BS 110a or a UE 120r) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE 120 or a BS 110) , or that relays transmissions between UEs 120, to facilitate communication between devices.

A network controller 130 may be in communication with a set of BSs 110 and provide coordination and control for these BSs 110 (e.g., via a backhaul) . In aspects, the network controller 130 may be in communication with a core network 132 (e.g., a 5G Core Network (5GC) ) , which provides various network functions such as Access and Mobility Management, Session Management, User Plane Function, Policy Control Function, Authentication Server Function, Unified Data Management, Application Function, Network Exposure Function, Network Repository Function, Network Slice Selection Function, etc. In certain aspects, the core network 132 and Radio Access Network (RAN) , including the BSs 110 and network controller 130, may operate in a 5G Standalone (SA) mode. In such a case, the BSs 110 in the RAN may be 5G NR gNBs, and the core network 132 may the 5GC, such that the user-plane traffic (e.g., eMBB and/or URLLC) and control-plane traffic are transferred through the 5G NR gNBs. In certain cases, the core network 132 and RAN may operate in 5G Non-standalone (NSA) mode. In such a case, the BSs 110 may have 5G NR gNBs and 4G eNBs, and the core network 132 is a 4G Evolved Packet Core, such that the control-plane traffic is transferred through the 4G eNBs, and the 5G user-plane (e.g., eMBB) may be transferred through the 5G gNBs.

FIG. 2 illustrates example components of BS 110a and UE 120a (e.g., the wireless communication network 100 of FIG. 1) , which may be used to implement aspects of the present disclosure. At the BS 110a, a transmit processor 220 may receive data from a data source 212 and control information from a controller/processor 240. The control information may be for the physical broadcast channel (PBCH) , physical control format indicator channel (PCFICH) , physical hybrid ARQ indicator channel (PHICH) , physical downlink control channel (PDCCH) , group common PDCCH (GC PDCCH) , etc. The data may be for the physical downlink shared channel (PDSCH) , etc. A medium access control (MAC) -control element (MAC-CE) is a MAC layer communication structure that may be used for control command exchange between wireless nodes. The MAC-CE may be carried in a shared channel such as a physical downlink shared channel (PDSCH) , a physical uplink shared channel (PUSCH) , or a physical sidelink shared channel (PSSCH) .

The processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, such as for the primary synchronization signal (PSS) , secondary synchronization signal (SSS) , PBCH demodulation reference signal (DMRS) , and channel state information reference signal (CSI-RS) . A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 232a-232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc. ) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 232a-232t may be transmitted via the antennas 234a-234t, respectively.

At the UE 120a, the antennas 252a-252r may receive the downlink signals from the BS 110a and may provide received signals to the demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc. ) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all the demodulators in the transceivers 254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120a to a data sink 260, and provide decoded control information to a controller/processor 280.

On the uplink, at UE 120a, a transmit processor 264 may receive and process data (e.g., for the physical uplink shared channel (PUSCH) ) from a data source 262 and control information (e.g., for the physical uplink control channel (PUCCH) from the controller/processor 280. The transmit processor 264 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS) ) . The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by the modulators in transceivers 254a-254r (e.g., for SC-FDM, etc. ) , and transmitted to the BS 110a. At the BS 110a, the uplink signals from the UE 120a may be received by the antennas 234, processed by the modulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by the UE 120a. The receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to the controller/processor 240.

The

memories

242 and 282 may store data and program codes for BS 110a and UE 120a, respectively. A scheduler 244 may schedule UEs for data transmission on the downlink and/or uplink.

Antennas 252,

processors

266, 258, 264, and/or controller/processor 280 of the UE 120a and/or antennas 234,

processors

220, 230, 238, and/or controller/processor 240 of the BS 110a may be used to perform the various techniques and methods described herein. As shown in FIG. 2, the controller/processor 280 of the UE 120a has a packet manager 281 that monitors the SNs of certain packets (e.g., PDCP packets) and resets a NAS session with the core network 132 if there is a jump in the SNs between consecutively received packets above or at a certain threshold, according to aspects described herein. Although shown at the controller/processor, other components of the UE 120a and BS 110a may be used to perform the operations described herein.

NR may utilize orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) on the uplink and downlink. NR may support half-duplex operation using time division duplexing (TDD) . OFDM and single-carrier frequency division multiplexing (SC-FDM) partition the system bandwidth into multiple orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. Modulation symbols may be sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers may be dependent on the system bandwidth. The minimum resource allocation, called a resource block (RB) , may be 12 consecutive subcarriers. The system bandwidth may also be partitioned into subbands. For example, a subband may cover multiple RBs. NR may support a base subcarrier spacing (SCS) of 15 KHz and other SCS may be defined with respect to the base SCS (e.g., 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc. ) .

FIG. 3A is a block diagram illustrating an example communication protocol stack 300A for a user plane, in accordance with certain aspects of the present disclosure. As shown, for user-plane traffic, the BS 110 and/or other network entities in a radio access network (RAN) may implement the protocol stack 300A having a Service Data Adaptation Protocol (SDAP) layer 302, a Packet Data Convergence Protocol (PDCP) layer 304, a Radio Link Control (RLC) layer 306, a Medium Access Control (MAC) layer 308, and a Physical (PHY) layer 310. The UE 120 may implement the protocol stack 300A with the SDAP layer 302, the PDCP layer 304, the RLC layer 306, the MAC layer 308, and the PHY layer 310.

In aspects, the SDAP layer 302 may map between QoS flow and data radio bearer and mark QoS flow identifiers (IDs) in downlink and uplink packets. The PDCP layer 304 may transfer data in the user plane or control plane, maintain of PDCP sequence numbers (SNs) , perform header compression and decompression, perform integrity protection and integrity verification; perform timer based Service Data Unit (SDU) discard, provide routing for split bearers, provide duplication, perform packet reordering and in-order delivery, provide packet out-of-order delivery, and discard duplicates. The RLC layer 306 may transfer upper layer Protocol Data Units (PDUs) , provide sequence numbering independent of the one in the PDCP layer 304, perform error correction through automatic repeat request (ARQ) , perform segmentation (AM and UM) and re-segmentation of RLC SDUs, perform reassembly of SDUs, detect duplicates, discard RLC SDUs, perform RLC re-establishment, and perform protocol error detection. The MAC layer 308 may map between logical channels and transport channels, perform multiplexing/demultiplexing of MAC SDUs belonging to one or different logical channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels, perform scheduling information reporting, perform error correction through Hybrid ARQ (HARQ) , provide priority handling between UEs by means of dynamic scheduling, provide priority handling between logical channels of one UE by means of logical channel prioritization, provide priority handling between overlapping resources of one UE, and provide padding. The PHY layer 310 may provide the transmission waveform (e.g., an OFDM using a cyclic prefix) for user-plane or control-plane traffic via over the air resources (e.g., time-frequency resources) between the UE 120 and BS 110.

FIG. 3B is a block diagram illustrating an example communication protocol stack 300B for a control plane, in accordance with certain aspects of the present disclosure. As shown, for the control plane, the core network 132 (e.g., the Access and Mobility Management Function (AMF) ) may implement a Non-Access Stratum (NAS) layer 312 of the protocol stack 300B, and the BS 110 and/or other network entities in the RAN may implement the remaining layers of the protocol stack 300B including a Radio Resource Control (RRC) layer 314, the PDCP layer 304, the RLC layer 306, the MAC layer 308, and the PHY layer 310. The UE 120 may implement the NAS layer 312, the RRC layer 314, the PDCP layer 304, the RLC layer 306, the MAC layer 308, and the PHY layer 310.

In aspects, the NAS layer 312 may provide mobility management functions of the UE 120 and session management functions to establish and maintain IP connectivity between the UE and the packet gate of the core network 130. The RRC layer 314 may broadcast system information, provide paging, manage an RRC connection between the UE and RAN, perform security functions including key management, manage Signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs) , provide mobility functions, provide QoS management functions, provide UE measurement reporting and control of the reporting, provide detection of and recovery from radio link failure, and NAS message transfer.

The protocol stacks 300A, 300B may be implemented by devices operating in a wireless communication system, such as a 5G NR system (e.g., the wireless communication network 100) . In various examples, the layers of the protocol stacks 300A, 300B may be implemented as separate modules of software, portions of a processor or an application specific integrated circuit (ASIC) , portions of non-collocated devices connected by a communications link, or various combinations thereof. Collocated and non-collocated implementations may be used, for example, in a protocol stack across the BS, RAN, or core network. That is, various layers of a protocol stack may be split or collocated across the BS, RAN, or core network, for example, as depicted in FIG. 3B.

Example Data Stall Recovery

In certain wireless communications systems (e.g., 5G NR) , a UE may experience a stall in downlink data due to a jump in sequence numbers between received PDCP packets. For example, when a UE is camped on an 5G NR cell in 5G standalone mode (e.g., the RAN is configured with an NR type PDCP to the UE) , and the downlink PDCP packet (e.g., a PDCP PDU) sequence number (SN) jumps or fluctuates dramatically after the PDCP is configured, the subsequently received PDPC packets may be dropped by the UE. In such a case, the downlink data to the UE is blocked from being processed any further in the protocol stack, and as a result, the UE may experience extended latency for downlink transmissions. In certain cases, the jump in the PDCP SN may occur due to a degradation in downlink channel conditions, decoding errors at the UE, or a drop in packets from a data network.

Aspects of the present disclosure provides a technique for recovering from and/or preventing a stalled downlink data connection. In aspects, the UE may monitor PDCP packets from the BS, and if there is a jump in the PDCP sequence number relative to a certain threshold, the UE may reestablish the NAS session (e.g., a mobility management session) with the core network. For example, if the difference between the sequence numbers of PDCP packets received at the UE is greater than or equal to a threshold, the UE may perform a deregistration procedure and a registration procedure for mobility management (e.g., at a NAS layer) at a network entity (e.g., the RAN and/or core network) .

FIG. 4 is a signaling flow diagram illustrating example operations 400 to recover and/or prevent a stall in downlink data, in accordance with certain aspects of the present disclosure. As shown, at 402, packet switched data may be transferred between the UE 120 and BS 110. That is, the UE 120 may have a PDU session established with the BS 110 to transmit to and/or receive data from the BS 110. In certain cases, the UE 120 may be communicating with the BS 110 in a 5G NR standalone mode, for example, as described herein with respect to FIG. 1. At 404, the UE 120 may receive a first packet and a second packet from the BS 110. In aspects, the first and second packets may be PDCP packets such as PDCP PDUs. In certain cases, the UE 120 may receive the first and second packets consecutively, for example, from consecutive RLC PDUs or within the same RLC PDU. In other words, the UE 120 may not receive other packets between the first and second packets. At 406, the UE 120 may determine that a difference between sequence numbers (SNs) for the first packet and the second packet is greater than or equal to a threshold. That is, there may be a significant jump between the SNs of the first and second packets, which may cause the downlink data to stall.

In response to the determination at 406, the UE 120 may perform a deregistration procedure and a registration procedure at the NAS layer of the control-plane protocol stack (e.g., the protocol stack 300B) . For example, at 408, the UE 120 may transmit a deregistration request message to the BS 110, which may forward the message to the core network (not shown) such as the AMF. At 410, the UE 120 may receive a deregistration accept message. After successful deregistration, the UE 120 may transmit a registration accept message at 412 to the BS 110, which may forward the message to the core network. At 414, the UE 120 may receive a registration accept message from the BS 110, and with registration at the NAS layer complete, the UE 120 may continue to receive downlink data from the BS 110. For example, at 416, packet switched data may be transferred between the UE 120 and BS 110. The deregistration and registration procedures may enable the UE 120 to recover from the potential downlink data stall and continue to receive downlink data.

FIG. 5 is a flow diagram illustrating example operations 500 for wireless communication, in accordance with certain aspects of the present disclosure. The operations 500 may be performed, for example, by a UE (e.g., the UE 120a in the wireless communication network 100) . The operations 500 may be implemented as software components that are executed and run on one or more processors (e.g., controller/processor 280 of FIG. 2) . Further, the transmission and reception of signals by the UE in the operations 500 may be enabled, for example, by one or more antennas (e.g., antennas 252 of FIG. 2) . In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller/processor 280) obtaining and/or outputting (providing) signals.

The operations 500 may begin at 502, where the UE obtains a first packet and a second packet from a network entity (e.g., the BS 110 and/or core network) . At 504, the UE may determine that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold. At 506, the UE may perform a deregistration procedure and a registration procedure for mobility management (e.g., at the NAS layer) at the network entity based on the determination.

In aspects, the first and second packets may be packets at the PDCP layer of a protocol stack (e.g., the PDCP layer 304 of protocol stack 300A) . That is, the first and second packets may be PDCP packets such as the PDCP PDUs.

In aspects, the UE may be communicating with the network entity through a PDU session in 5G NR standalone mode. For example, obtaining the first packet and the second packet at 502 may include obtaining the first packet and the second packet via a PDU session in 5G standalone mode. That is, the UE may communicate with the network entity in a Fifth Generation (5G) New Radio (NR) standalone mode, which may include obtaining the first packet and the second packet at 502. In other words, obtaining the first packet and the second packet at 502 may include obtaining the first packet and the second packet via a 5G NR radio access technology, for example, as provided in the 3GPP standards.

In certain aspects, the deregistration procedure may deregister the UE from various mobility management functions at the core network, for example, through the NAS layer of a protocol stack. Performing the deregistration procedure at 506 may include providing a deregistration request message for transmission to the network entity and obtaining a deregistration accept message from the network entity. In aspects, the deregistration request message may be forwarded to the core network by a BS, and the deregistration accept message may be forwarded to the UE by the BS.

In certain aspects, the registration procedure may register the UE from various mobility management functions at the core network, for example, through the NAS layer of a protocol stack. The registration procedure may be performed after the deregistration procedure is successfully performed, for example, after the UE receives the deregistration accept message. Performing the registration procedure at 506 may include providing a registration request message to the network entity and obtaining a registration accept message from the network entity.

After the deregistration and registration procedures are performed, the UE may continue to communicate with the network entity via a PDU session. In other words, the deregistration and registration procedures may reset the PDU session to recover from or prevent a stall in downlink data. For example, the operations 500 may include obtaining additional packets (e.g., PDCP packets) from the network entity after performing the deregistration procedure and the registration procedure. In aspects, the deregistration and registration procedures may enable the UE to quickly recover or prevent a stall in downlink data due to the jump in SNs between received packets.

As used herein, a network entity may refer to a network device and/or wireless communication device in the RAN (e.g., the BS 110 and/or network controller 132) and/or core network (e.g., the AMF) .

FIG. 6 illustrates a communications device 600 that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated in FIG. 5. The communications device 600 includes a processing system 602 coupled to a transceiver 608 (e.g., a transmitter and/or a receiver) . The transceiver 608 is configured to transmit and receive signals for the communications device 600 via an antenna 610, such as the various signals as described herein. The processing system 602 may be configured to perform processing functions for the communications device 600, including processing signals received and/or to be transmitted by the communications device 600.

The processing system 602 includes a processor 604 coupled to a computer-readable medium/memory 612 via a bus 606. In certain aspects, the computer-readable medium/memory 612 is configured to store instructions (e.g., computer-executable code) that when executed by the processor 604, cause the processor 604 to perform the operations illustrated in FIG. 5, or other operations for performing the various techniques discussed herein for recovering from the downlink data stall. In certain aspects, computer-readable medium/memory 612 stores code for obtaining 614 (e.g., code for receiving) , code for providing 616 (e.g., code for transmitting) , code for determining 618, and/or code for performing 620 (e.g., code for receiving and/or code for transmitting) . In certain aspects, the processor 604 has circuitry configured to implement the code stored in the computer-readable medium/memory 612. The processor 604 includes circuitry for obtaining 624 (e.g., circuitry for receiving) , circuitry for providing 626 (e.g., circuitry for transmitting) , circuitry for determining 628, and/or circuitry for performing 630 (e.g., circuitry for receiving and/or circuitry for transmitting) .

The techniques described herein may be used for various wireless communication technologies, such as NR (e.g., 5G NR) , 3GPP Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal frequency division multiple access (OFDMA) , single-carrier frequency division multiple access (SC-FDMA) , time division synchronous code division multiple access (TD-SCDMA) , and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA) , cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA network may implement a radio technology such as NR (e.g. 5G RA) , Evolved UTRA (E-UTRA) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS) . LTE and LTE-A are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP) . cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . NR is an emerging wireless communications technology under development.

In 3GPP, the term “cell” can refer to a coverage area of a Node B (NB) and/or a NB subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term “cell” and BS, next generation NodeB (gNB or gNodeB) , access point (AP) , distributed unit (DU) , carrier, or transmission reception point (TRP) may be used interchangeably. A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG) , UEs for users in the home, etc. ) . A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS.

A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE) , a cellular phone, a smart phone, a personal digital assistant (PDA) , a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc. ) , an entertainment device (e.g., a music device, a video device, a satellite radio, etc. ) , a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered machine-type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a BS, another device (e.g., remote device) , or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., a BS) allocates resources for communication among some or all devices and equipment within its service area or cell. The scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity. Base stations are not the only entities that may function as a scheduling entity. In some examples, a UE may function as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs) , and the other UEs may utilize the resources scheduled by the UE for wireless communication. In some examples, a UE may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs may communicate directly with one another in addition to communicating with a scheduling entity.

The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure) , ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information) , accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

The previous 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 readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112 (f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for. ”

The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component (s) and/or module (s) , including, but not limited to a circuit, an application specific integrated circuit (ASIC) , or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device (PLD) , discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

If implemented in hardware, an example hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the case of a user terminal (see FIG. 1) , a user interface (e.g., keypad, display, mouse, joystick, etc. ) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system.

If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer readable medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory) , flash memory, ROM (Read Only Memory) , PROM (Programmable Read-Only Memory) , EPROM (Erasable Programmable Read-Only Memory) , EEPROM (Electrically Erasable Programmable Read-Only Memory) , registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product.

A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.

Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared (IR) , radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk, and

disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Thus, in some aspects computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media) . In addition, for other aspects computer-readable media may comprise transitory computer-readable media (e.g., a signal) . Combinations of the above should also be included within the scope of computer-readable media.

Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein, for example, instructions for performing the operations described herein and illustrated in FIG. 5.

Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc. ) , such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.

It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

A method of wireless communications, comprising:

obtaining a first packet and a second packet from a network entity;

determining that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold; and

performing a deregistration procedure and a registration procedure for mobility management at the network entity based on the determination.
The method of claim 1, wherein the first packet and the second packet are packet data convergence protocol (PDCP) packets.
The method of claim 1, wherein performing the deregistration procedure comprises:

providing a deregistration request message for transmission to the network entity; and

obtaining a deregistration accept message from the network entity.
The method of claim 1, wherein performing the registration procedure comprises:

providing a registration request message to the network entity; and

obtaining a registration accept message from the network entity.
The method of claim 1, wherein obtaining the first packet and the second packet comprises obtaining the first packet and the second packet via a protocol data unit

(PDU) session.
The method of claim 1, further comprising obtaining additional packets from the network entity after performing the deregistration procedure and the registration procedure.
The method of claim 1, further comprising communicating with the network entity in a Fifth Generation (5G) New Radio (NR) standalone mode, wherein the communication comprises obtaining the first packet and the second packet.
The method of claim 1, wherein obtaining the first packet and the second packet comprises obtaining the first packet and the second packet via a 5G NR radio access technology.
An apparatus for wireless communications, comprising:

means for obtaining a first packet and a second packet from a network entity;

means for determining that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold; and

means for performing a deregistration procedure and a registration procedure for mobility management at the network entity based on the determination.
The apparatus of claim 9, wherein the first packet and the second packet are packet data convergence protocol (PDCP) packets.
The apparatus of claim 9, wherein the means for performing the deregistration procedure comprises:

means for providing a deregistration request message for transmission to the network entity; and

means for obtaining a deregistration accept message from the network entity.
The apparatus of claim 9, wherein the means for performing the registration procedure comprises:

means for providing a registration request message to the network entity; and

means for obtaining a registration accept message from the network entity.
The apparatus of claim 9, wherein the means for obtaining the first packet and the second packet comprises means for obtaining the first packet and the second packet via a protocol data unit (PDU) session.
The apparatus of claim 9, further comprising means for obtaining additional packets from the network entity after performing the deregistration procedure and the registration procedure.
The apparatus of claim 9, further comprising means for communicating with the network entity in a Fifth Generation (5G) New Radio (NR) standalone mode, wherein the communication comprises obtaining the first packet and the second packet.
The apparatus of claim 9, wherein the means for obtaining the first packet and the second packet comprises means for obtaining the first packet and the second packet via a 5G NR radio access technology.
An apparatus for wireless communications, comprising:

a processing system configured to:

obtain a first packet and a second packet from a network entity;

determine that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold; and

perform a deregistration procedure and a registration procedure for mobility management at the network entity based on the determination.
The apparatus of claim 17, wherein the first packet and the second packet are packet data convergence protocol (PDCP) packets.
The apparatus of claim 17, wherein the processing system performs the deregistration procedure by:

providing a deregistration request message for transmission to the network entity; and

obtaining a deregistration accept message from the network entity.
The apparatus of claim 17, wherein the processing system performs the registration procedure by:

providing a registration request message to the network entity; and

obtaining a registration accept message from the network entity.
The apparatus of claim 17, wherein the processing system obtains the first packet and the second packet by obtaining the first packet and the second packet via a protocol data unit (PDU) session.
The apparatus of claim 17, wherein the processing system is further configured to obtain additional packets from the network entity after performing the deregistration procedure and the registration procedure.
The apparatus of claim 17, wherein the processing system is further configured to communicate with the network entity in a Fifth Generation (5G) New Radio (NR) standalone mode, said communication obtaining the first packet and the second packet.
The apparatus of claim 17, wherein the processing system obtains the first packet and the second packet by obtaining the first packet and the second packet via a 5G NR radio access technology.
A user equipment, comprising:

a receiver configured to receive a first packet and a second packet from a network entity; and

a processing system configured to:

determine that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold; and

perform a deregistration procedure and a registration procedure for mobility management at the network entity based on the determination.
A computer-readable medium for wireless communications, comprising instructions executable to:

obtain a first packet and a second packet from a network entity;

determine that a difference between sequence numbers for the first packet and the second packet is greater than or equal to a threshold; and

perform a deregistration procedure and a registration procedure for mobility management at the network entity based on the determination.