WO2021208057A1

WO2021208057A1 - Detecting and recovering from data stall of an anchoring cell

Info

Publication number: WO2021208057A1
Application number: PCT/CN2020/085271
Authority: WO
Inventors: Pan JIANG; Yuankun ZHU; Chaofeng HUI; Miao Fu; Yi Liu; Jian Li; Hao Zhang; Wei He; Fojian ZHANG
Original assignee: Qualcomm Incorporated
Priority date: 2020-04-17
Filing date: 2020-04-17
Publication date: 2021-10-21

Abstract

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may detect a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell, and prevent the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers. Numerous other aspects are provided.

Description

DETECTING AND RECOVERING FROM DATA STALL OF AN ANCHORING CELL

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wireless communication and to techniques and apparatuses for detecting and recovering from data stall of an anchoring cell.

BACKGROUND

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical 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, and/or the like) . Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, orthogonal frequency-division multiple access (OFDMA) systems, single-carrier frequency-division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and Long Term Evolution (LTE) . LTE/LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP) .

A wireless communication network may include a number of base stations (BSs) that can support communication for a number of user equipment (UEs) . A user equipment (UE) may communicate with a base station (BS) via the downlink and uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS may be referred to as a Node B, a gNB, an access point (AP) , a radio head, a transmit receive point (TRP) , a New Radio (NR) BS, a 5G Node B, and/or the like.

The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipment to communicate on a municipal, national, regional, and even global level. New Radio (NR) , which may also be referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (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 orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL) , using CP-OFDM and/or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM) ) on the uplink (UL) , as well as supporting 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 LTE and NR technologies. Preferably, these improvements should be applicable to other multiple access technologies and the telecommunication standards that employ these technologies.

SUMMARY

In some aspects, a method of wireless communication, performed by a user equipment (UE) , may include detecting a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell, and preventing the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers.

In some aspects, a method of wireless communication, performed by a UE, may include detecting a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell based at least in part on a difference between sequence numbers of the PDCP packets satisfying a threshold value, and triggering a radio link failure (RLF) procedure based at least in part on detecting the jump in PDCP sequence numbers.

In some aspects, a UE for wireless communication may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to detect a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell, and prevent the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers.

In some aspects, a UE for wireless communication may include a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to detect a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell based at least in part on a difference between sequence numbers of the PDCP packets satisfying a threshold value, and trigger a radio link failure procedure based at least in part on detecting the jump in PDCP sequence numbers.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to detect a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell, and prevent the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the one or more processors to detect a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell based at least in part on a difference between sequence numbers of the PDCP packets satisfying a threshold value, and trigger an RLF procedure based at least in part on detecting the jump in PDCP sequence numbers.

In some aspects, an apparatus for wireless communication may include means for detecting a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell, and means for preventing the apparatus from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers.

In some aspects, an apparatus for wireless communication may include means for detecting a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell based at least in part on a difference between sequence numbers of the PDCP packets satisfying a threshold value, and means for triggering a radio link failure procedure based at least in part on detecting the jump in PDCP sequence numbers.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and/or processing system as substantially described herein with reference to and as illustrated by the drawings and specification.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purposes of illustration and description, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that 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 appended 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. The same reference numbers in different drawings may identify the same or similar elements.

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

Fig. 2 is a block diagram conceptually illustrating an example of a base station in communication with a UE in a wireless communication network, in accordance with various aspects of the present disclosure.

Fig. 3 is a diagram illustrating an example New Radio non-standalone architecture, in accordance with various aspects of the present disclosure.

Figs. 4A and 4B are diagrams illustrating one or more examples of detecting and recovering from data stall of an anchoring cell, in accordance with various aspects of the present disclosure.

Fig. 5 is a diagram illustrating an example process performed, for example, by a user equipment, in accordance with various aspects of the present disclosure.

Fig. 6 is a diagram illustrating an example process performed, for example, by a user equipment, in accordance with various aspects of the present disclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. 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.

Several aspects of telecommunication systems will now be presented with reference to various apparatuses and techniques. These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, and/or the like (collectively referred to as “elements” ) . These elements may be implemented using hardware, software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

It should be noted that while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

Fig. 1 is a diagram illustrating a wireless network 100 in which aspects of the present disclosure may be practiced. The wireless network 100 may be an LTE network or some other wireless network, such as a 5G or NR network. The wireless network 100 may include a number of BSs 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with user equipment (UEs) and may also be referred to as a base station, an NR BS, a Node B, a gNB, a 5G node B (NB) , an access point, a transmit receive point (TRP) , and/or the like. Each BS may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a BS and/or a BS subsystem serving this coverage area, depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or another type of cell. 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 association with the femto cell (e.g., UEs in a closed subscriber group (CSG) ) . 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. In the example shown in Fig. 1, a BS 110a may be a macro BS for a macro cell 102a, a BS 110b may be a pico BS for a pico cell 102b, and a BS 110c may be a femto BS for a femto cell 102c. A BS may support one or multiple (e.g., three) cells. The terms “eNB” , “base station” , “NR BS” , “gNB” , “TRP” , “AP” , “node B” , “5G NB” , and “cell” may be used interchangeably herein.

In some aspects, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some aspects, the BSs may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces such as a direct physical connection, a virtual network, and/or the like using any suitable transport network.

Wireless network 100 may also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and send a transmission of the data to a downstream station (e.g., a UE or a BS) . A relay station may also be a UE that can relay transmissions for other UEs. In the example shown in Fig. 1, a relay station 110d may communicate with macro BS 110a and a UE 120d in order to facilitate communication between BS 110a and UE 120d. A relay station may also be referred to as a relay BS, a relay base station, a relay, and/or the like.

Wireless network 100 may be a heterogeneous network that includes BSs of different types (e.g., macro BSs, pico BSs, femto BSs, relay BSs, and/or the like) . These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless network 100. For example, macro BSs may have a high transmit power level (e.g., 5 to 40 watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (e.g., 0.1 to 2 watts) .

A network controller 130 may couple to a set of BSs and may provide coordination and control for these BSs. Network controller 130 may communicate with the BSs via a backhaul. The BSs may also communicate with one another, e.g., directly or indirectly via a wireless or wireline backhaul.

UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, and/or the like. A UE may be a cellular phone (e.g., 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, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet) ) , an entertainment device (e.g., a music or video device, or a satellite radio) , a vehicular component or sensor, smart meters/sensors, 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) or evolved or enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, and/or the like, that may communicate with a base station, 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, and/or may be implemented as NB-IoT (narrowband internet of things) devices. Some UEs may be considered a Customer Premises Equipment (CPE) . UE 120 may be included inside a housing that houses components of UE 120, such as processor components, memory components, and/or the like. In some aspects, the processor components and the memory components may be coupled together. For example, the processor components (e.g., one or more processors) and the memory components (e.g., a memory) may be operatively coupled, communicatively coupled, electronically coupled, electrically coupled, and/or the like.

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, and/or the like. A frequency may also be referred to as a carrier, a frequency channel, and/or the like. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., without using a base station 110 as an intermediary to communicate with one another) . For example, the UEs 120 may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (e.g., which may include a vehicle-to-vehicle (V2V) protocol, a vehicle-to-infrastructure (V2I) protocol, and/or the like) , a mesh network, and/or the like. In this case, the UE 120 may perform scheduling operations, resource selection operations, and/or other operations described elsewhere herein as being performed by the base station 110.

As indicated above, Fig. 1 is provided as an example. Other examples may differ from what is described with regard to Fig. 1.

Fig. 2 shows a block diagram of a design 200 of base station 110 and UE 120, which may be one of the base stations and one of the UEs in Fig. 1. Base station 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T ≥ 1 and R ≥ 1.

At base station 110, a transmit processor 220 may receive data from a data source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (e.g., encode and modulate) the data for each UE based at least in part on the MCS (s) selected for the UE, and provide data symbols for all UEs. Transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI) and/or the like) and control information (e.g., CQI requests, grants, upper layer signaling, and/or the like) and provide overhead symbols and control symbols. Transmit processor 220 may also generate reference symbols for reference signals (e.g., the cell-specific reference signal (CRS) ) and synchronization signals (e.g., the primary synchronization signal (PSS) and secondary synchronization signal (SSS) ) . A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, the overhead symbols, and/or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM and/or the like) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. According to various aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.

At UE 120, antennas 252a through 252r may receive the downlink signals from base station 110 and/or other base stations and may provide received signals to demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM and/or the like) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 120 to a data sink 260, and provide decoded control information and system information to a controller/processor 280. A channel processor may determine reference signal received power (RSRP) , received signal strength indicator (RSSI) , reference signal received quality (RSRQ) , channel quality indicator (CQI) , and/or the like. In some aspects, one or more components of UE 120 may be included in a housing.

On the uplink, at UE 120, a transmit processor 264 may receive and process data from a data source 262 and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, and/or the like) from controller/processor 280. Transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, and/or the like) , and transmitted to base station 110. At base station 110, the uplink signals from UE 120 and other UEs may be received by antennas 234, processed by demodulators 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 UE 120. Receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to controller/processor 240. Base station 110 may include communication unit 244 and communicate to network controller 130 via communication unit 244. Network controller 130 may include communication unit 294, controller/processor 290, and memory 292.

Controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform one or more techniques associated with detecting and recovering from data stall of an anchoring cell, as described in more detail elsewhere herein. For example, controller/processor 240 of base station 110, controller/processor 280 of UE 120, and/or any other component (s) of Fig. 2 may perform or direct operations of, for example, process 500 of Fig. 5, process 600 of Fig. 6, and/or other processes as described herein.

Memories

242 and 282 may store data and program codes for base station 110 and UE 120, respectively. In some aspects, memory 242 and/or memory 282 may comprise a non-transitory computer-readable medium storing one or more instructions for wireless communication. For example, the one or more instructions, when executed (e.g., directly, or after compiling, converting, interpreting, and/or the like) by one or more processors of the base station 110 and/or the UE 120, may perform or direct operations of, for example, process 500 of Fig. 5, process 600 of Fig. 6, and/or other processes as described herein. In some aspects, executing instructions may include running the instructions, converting the instructions, compiling the instructions, interpreting the instructions, and/or the like. A scheduler 246 may schedule UEs for data transmission on the downlink and/or uplink.

In some aspects, UE 120 may include means for detecting a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell, means for preventing the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers, means for detecting a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell based at least in part on a difference between sequence numbers of the PDCP packets satisfying a threshold value, means for triggering a radio link failure (RLF) procedure based at least in part on detecting the jump in PDCP sequence numbers, and/or the like. In some aspects, such means may include one or more components of UE 120 described in connection with Fig. 2, such as controller/processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, and/or the like.

As indicated above, Fig. 2 is provided as an example. Other examples may differ from what is described with regard to Fig. 2.

Fig. 3 is a diagram illustrating an example 300 NR non-standalone (NSA) architecture, in accordance with various aspects of the present disclosure.

As shown in Fig. 3, in an NR or 5G NSA mode, a UE 120 may communicate with both an eNB (e.g., a 4G base station 110) and a gNB (e.g., a 5G base station 110) , and the eNB and the gNB may communicate (e.g., directly or indirectly) with a 4G/LTE core network, shown as an evolved packet core (EPC) that includes a mobility management entity (MME) , a packet data network gateway (PGW) , a serving gateway (SGW) , and/or the like. In Fig. 3, the PGW and the SGW are shown collectively as P/SGW. In some aspects, the eNB and the gNB may be co-located at the same base station 110. In some aspects, the eNB and the gNB may be included in different base stations 110 (e.g., may not be co-located) .

In some aspects, a wireless network that permits operation in a 5G NSA mode may permit such operations using a master cell group (MCG) for a first RAT (e.g., an LTE RAT, a 4G RAT, and/or the like) and a secondary cell group (SCG) for a second RAT (e.g., an NR RAT, a 5G RAT, and/or the like) . In this case, the UE 120 may communicate with the eNB via the MCG, and may communicate with the gNB via the SCG. In some aspects, the MCG may anchor a network connection between the UE 120 and the 4G/LTE core network (e.g., for mobility, coverage, control plane information, and/or the like) , and the SCG may be added as one or more additional carriers to increase throughput (e.g., for data traffic, user plane information, and/or the like) . In some aspects, the gNB and the eNB may not transfer user plane information between one another.

In some aspects, the 5G NSA mode may be an Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) -NR dual connectivity (ENDC) mode or an NR-E-UTRA dual connectivity (NEDC) mode. In some aspects, a UE 120 operating in the ENDC mode or the NEDC mode may have dual connectivity with an LTE base station 110 (e.g., an eNB) and an NR base station 110 (e.g., a gNB) .

In some aspects, an anchoring MCG (e.g., for an LTE RAT) may be configured with an NR PDCP configuration. In some aspects, the anchoring MCG may utilize the NR PDCP configuration to transmit PDCP packets to the UE 120. In some aspects, the PDCP packets may be encapsulated in radio link control (RLC) packets. The MCG may associate each PDCP packet with a sequence number. For example, the MCG may use the NR PDCP configuration to add a PDCP sequence number to a protocol data unit (PDU) transmitted by the MCG. The UE 120 may use the PDCP sequence number of the PDCP packet to determine whether to accept or reject (e.g., drop) the PDCP packet (or other packets associated with the PDCP packet) , to determine whether the PDCP packet has been received in order, and/or the like.

In some aspects, an anchoring LTE MCG configured with an NR PDCP configuration may cause the PDCP sequence numbers added to PDCP packets to jump or fluctuate. In some aspects, the jump or fluctuation in the PDCP sequence numbers may be dramatic, such as jumping or fluctuating by up to 10,000 sequence numbers or more between one PDCP packet and a next PDCP packet. Transmitting PDCP packets after such a jump in PDCP sequence numbers may be problematic, as it may cause the UE 120 to reject or drop PDCP packets received after the jump in PDCP sequence numbers (e.g., based at least in part on the PDCP sequence numbers after the jump in PDCP sequence numbers no longer being in an acceptable range of PDCP sequence numbers) . As a result, the UE 120 may experience a data stall (e.g., a loss of data, a termination of the transmission of data, and/or the like) as all PDCP packets received after the jump in PDCP sequence numbers may be dropped.

Some techniques and apparatuses described herein enable a UE 120 to detect a jump in PDCP sequence numbers between PDCP packets received from an NSA anchoring cell, and prevent the UE 120 from connecting with or camping on (e.g., selecting or latching on to a cell in an idle mode) the NSA anchoring cell after detecting the jump in PDCP sequence numbers. As a result, the UE 120 may quickly detect and recover from a data stall caused by the NSA anchoring cell. In this way, the UE 120 may conserve network resources (e.g., time resources, frequency resources, spatial resources, resource elements, and/or the like) , UE resources (e.g., battery power, processing resources, and/or the like) , and/or the like that would have been otherwise used receiving and/or processing packets from the NSA anchoring cell after the jump in PDCP sequence numbers. Moreover, the UE 120 may conserve network resources, UE resources, and/or the like that would have been otherwise used reconnecting with or re-camping on the NSA anchoring cell after determining that the NSA anchoring cell is problematic (e.g., based at least in part on detecting the jump in PDCP sequence numbers) .

As indicated above, Fig. 3 is provided as an example. Other examples may differ from what is described with respect to Fig. 3.

Figs. 4A and 4B are diagrams illustrating one or more examples 400 of detecting and recovering from data stall of an anchoring cell, in accordance with various aspects of the present disclosure. As shown in Figs. 4A and 4B, a UE 120 may be camped on and/or connected with a first cell (e.g., associated with a first BS 110) and/or a second cell (e.g., associated with a second BS 110) . The first cell may be a master cell group (MCG) operating in an NSA architecture, as described above. In some aspects, the first cell uses an LTE RAT. In some aspects, the second cell may be a different MCG using an LTE RAT, an NR/5G cell, a cell operating in an NSA mode, a cell operating in a non-NSA mode, and/or the like.

As shown in Fig. 4A, and by reference number 405, the UE 120 may receive PDCP packets from the first BS 110 of the first cell. For example, the first cell may be configured with an NR PDCP configuration. The first cell may transmit PDCP packets (e.g., PDCP protocol data units (PDUs) ) to the UE 120. The first cell may add a PDCP sequence number to each PDCP packet transmitted by the first cell. The PDCP sequence number may be a number (e.g., a 12-bit number, an 18-bit number, and/or the like) that is added to a header of the PDCP packet. In some aspects, the first cell may generate PDCP sequence numbers sequentially (e.g., a first PDCP packet transmitted may have a first PDCP sequence number and a next PDCP packet transmitted may have the next PDCP sequence number in a sequence) .

In some aspects, the UE 120 may use the PDCP sequence numbers to determine whether to accept or reject (e.g., drop) a PDCP packet (or other packets associated with the PDCP packet) , to determine whether the PDCP packet has been received in order, and/or the like. For example, the UE 120 may compare the PDCP sequence number of a received PDCP packet to an acceptable range of PDCP sequence numbers. If the PDCP sequence number of the received PDCP packet is not in the acceptable range of PDCP sequence numbers, the UE 120 may drop the received PDCP packet.

In some aspects, the first cell may experience a problem that causes the first cell to cause the PDCP sequence numbers added to PDCP packets to jump or fluctuate, such as jumping or fluctuating by up to 10,000 sequence numbers or more between one PDCP packet and a next PDCP packet. As a result, the UE 120 may drop all PDCP packets received after the first cell jumps the PDCP sequence numbers. This may cause a data stall (e.g., a loss of data, a termination of the transmission of data, and/or the like) as data associated with the dropped PDCP packets may not be received and/or processed by the UE 120.

As shown by reference number 410, the UE 120 may detect a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell. For example, the UE 120 may receive a first PDCP packet associated with a first PDCP sequence number in a first slot. The UE 120 may receive a second PDCP packet associated with a second PDCP sequence number in a second slot. The UE 120 may compare the first PDCP sequence number to the second PDCP sequence number. The UE 120 may determine that a difference between the first sequence number and the second sequence number satisfies a threshold value (e.g., a PDCP sequence number jump threshold) .

In some aspects, the second PDCP packet may be a PDCP packet that is received directly after the first PDCP packet (e.g., the second PDCP packet may be the next PDCP packet received after the first PDCP packet) . In some aspects, the second PDCP packet may be a PDCP packet received a certain amount of time after the first PDCP packet. In some aspects, the first slot and the second slot may be consecutive slots. In some aspects, the first slot may be a slot in which the first PDCP packet is received and the second slot may be a slot in which the next PDCP packet is received. In some aspects, the first PDCP packet and the second PDCP packet may be received in the same slot.

In some aspects, the UE 120 may determine the threshold value based at least in part on a configuration of the UE 120. For example, the threshold value may be based at least in part on a telecommunication standard, a Technical Specification, a network in which the UE 120 is located, and/or the like. In some aspects, the UE 120 may receive an indication of the threshold value from the first BS 110 of the first cell.

As shown by reference number 415, the UE 120 may trigger a radio link failure (RLF) procedure based at least in part on detecting the jump in PDCP sequence numbers. For example, the UE 120 may determine an RLF with the first cell based at least in part on detecting the jump in PDCP sequence numbers. The UE 120 may terminate a connection with the first cell based at least in part on triggering the RLF procedure, thereby avoiding communication performance losses that may result from the jump in PDCP sequence numbers. In some aspects, the UE 120 may flag or blacklist the first cell (e.g., by transmitting an indication to other BSs and/or to other UEs) to indicate that a jump in PDCP sequence numbers was detected in the first cell.

As shown by reference number 420, the UE 120 may initiate or start a timer to prevent connecting with or camping on the first cell based at least in part on triggering the RLF procedure and/or detecting the jump in PDCP sequence numbers. The timer may be a cell bar timer, such that the UE 120 is barred or prevented from establishing a connection with the first cell until the timer has expired. In some aspects, the timer prevents the UE 120 from connecting with the first cell during a radio resource control (RRC) idle mode of the UE 120.

As shown by reference number 425, the UE 120 may perform a cell search procedure after terminating the connection with the first cell. According to the cell search procedure, the UE 120 may perform measurements of a plurality of candidate cells to enable selection of a new cell. In some aspects, the timer may prevent the UE 120 from connecting with or choosing the first cell during the cell search procedure. In some aspects, the cell search procedure may result in the UE 120 selecting the second cell to connect with or camp on.

As shown by reference number 430, the UE 120 may connect with or camp on the second cell based at least in part on performing the cell search procedure. For example, the UE 120 may select the second cell and may camp on the second cell in an RRC idle mode.

As shown in Fig. 4B, and by reference number 435, after connecting with or camping on the second cell, the UE 120 may receive an RRC communication from the second BS 110 of the second cell and enter an RRC connected mode on the second cell. The UE 120 may communicate with the second BS 110 of the second cell.

As shown by reference number 440, the UE 120 may perform measurements of one or more neighboring cells. For example, the UE 120 may perform measurements (such as on signals of the second cell or neighboring cells) and transmit a measurement report to the second BS 110 of the second cell. For example, the measurement report may indicate a reference signal receive power parameter, a reference signal receive quality parameter, a received signal strength indication parameter, a signal-to- interference-plus-noise-ratio parameter, and/or the like of measurement objects of the second cell or neighboring cells. The second BS 110 of the second cell may use the measurement report to determine whether to handover the UE 120 to another BS 110 of another cell.

As shown by reference number 445, the UE 120 may receive and identify a measurement from the first cell based at least in part on performing the measurement of one or more neighboring cells. For example, the UE 120 may identify a measurement object of the first cell from the measurements of one or more neighboring cells. The UE 120 may identify the measurement object of the first cell from the measurements of one or more neighboring cells based at least in part on an identifier of the first cell, an identifier of the first BS 110 of the first cell, and/or the like.

As shown by reference number 450, the UE 120 may prune or remove the measurement object of the first cell from the measurements of the one or more neighboring cells based at least in part on detecting the jump in PDCP sequence numbers in the first cell. For example, the UE 120 may identify measurements include measurement objects associated with the first cell, a third cell, and a fourth cell. The UE 120 may prune or remove the measurement object associated with the first cell from the measurements. The UE 120 may generate a measurement report that indicates the measurements objects of the third cell and the fourth cell. As a result, the UE 120 may not transmit a corresponding measurement report that indicates the measurement object of the first cell. For example, the UE 120 may flag or blacklist the first cell, such that the UE 120 knows there is a PDCP sequence number issue in the first cell. The UE 120 may prune or remove any measurement objects of the first cell identified by the UE 120. In some aspects, the UE 120 may prune or remove the measurement objects of the first cell for a certain amount of time after detecting the jump in PDCP sequence numbers in the first cell. In some aspects, the UE 120 may prune or remove the measurement objects of the first cell until the UE 120 receives an indication that the PDCP sequence number issue of the first cell has been resolved.

As shown by reference number 455, the UE 120 may transmit one or more measurement reports, without the measurement associated with the first cell, to the second BS 110 of the second cell based at least in part on detecting the jump in PDCP sequence numbers. As a result, the second BS 110 of the second cell will not attempt to handover the UE 120 to the first cell as the one or more measurement reports received by the second BS 110 of the second cell will not indicate any measurement objects of the first cell. In this way, the UE 120 may prevent or bar the UE 120 from camping on or connecting with the first cell while the UE 120 is in an RRC connected mode on the second cell. The UE 120 may continue to communicate with the second BS 110 of the second cell (or other BSs 110 of other cells) without experiencing the communication performance losses that may result from the jump in PDCP sequence numbers in the first cell.

Therefore, the UE 120 may quickly detect and recover from a data stall caused by the jump in PDCP sequence numbers in the first cell. In this way, the UE 120 may conserve network resources, UE resources, and/or the like that would have been otherwise used receiving and/or processing packets from the NSA anchoring cell after the jump in PDCP sequence numbers. Moreover, the UE 120 may conserve network resources, UE resources, and/or the like that would have been otherwise used reconnecting with or re-camping on the first cell after determining that the first cell is problematic (e.g., based at least in part on detecting the jump in PDCP sequence numbers) .

As indicated above, Figs. 4A and 4B are provided as one or more examples. Other examples may differ from what is described with respect to Figs. 4A and 4B.

Fig. 5 is a diagram illustrating an example process 500 performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process 500 is an example where the UE (e.g., UE 120 and/or the like) performs operations associated with detecting and recovering from data stall of an anchoring cell.

As shown in Fig. 5, in some aspects, process 500 may include detecting a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell (block 510) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may detect a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell, as described above.

As further shown in Fig. 5, in some aspects, process 500 may include preventing the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers (block 520) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may prevent the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers, as described above.

Process 500 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, process 500 includes triggering a radio link failure procedure based at least in part on detecting the jump in PDCP sequence numbers.

In a second aspect, alone or in combination with the first aspect, detecting the jump in PDCP sequence numbers comprises: receiving a first PDCP packet associated with a first sequence number in a first slot; receiving a second PDCP packet associated with a second sequence number in a second slot; comparing the first sequence number to the second sequence number, and determining that a difference between the first sequence number and the second sequence number satisfies a threshold value.

In a third aspect, alone or in combination with one or more of the first and second aspects, the threshold value is determined based at least in part on a configuration of the UE.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, process 500 includes performing a cell search procedure based at least in part on triggering a radio link failure procedure, and connecting with a second cell based at least in part on performing the cell search procedure.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, preventing the UE from camping on or connecting with the first cell comprises: initiating a timer based at least in part on triggering a radio link failure procedure, and preventing a connection with the first cell during a radio resource control idle mode based at least in part on the timer.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, preventing the UE from camping on or connecting with the first cell comprises: entering a radio resource control connected mode on a second cell based at least in part on a performed cell search procedure, performing measurements of one or more neighboring cells, identifying a measurement associated with the first cell from the measurements of the one or more neighboring cells, and transmitting a measurement report without the measurement associated with the first cell to a base station of the second cell based at least in part on detecting the jump in PDCP sequence numbers.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, the first cell is a non-standalone Long Term Evolution (LTE) cell that includes a New Radio (NR) PDCP configuration.

Although Fig. 5 shows example blocks of process 500, in some aspects, process 500 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 5. Additionally, or alternatively, two or more of the blocks of process 500 may be performed in parallel.

Fig. 6 is a diagram illustrating an example process 600 performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process 600 is an example where the UE (e.g., UE 120 and/or the like) performs operations associated with detecting and recovering from data stall of an anchoring cell.

As shown in Fig. 6, in some aspects, process 600 may include detecting a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell based at least in part on a difference between sequence numbers of the PDCP packets satisfying a threshold value (block 610) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may detect a jump in PDCP sequence numbers between PDCP packets received from a base station of a first cell based at least in part on a difference between sequence numbers of the PDCP packets satisfying a threshold value, as described above.

As further shown in Fig. 6, in some aspects, process 600 may include triggering a radio link failure (RLF) procedure based at least in part on detecting the jump in PDCP sequence numbers (block 620) . For example, the UE (e.g., using receive processor 258, transmit processor 264, controller/processor 280, memory 282, and/or the like) may trigger an RLF procedure based at least in part on detecting the jump in PDCP sequence numbers, as described above.

Process 600 may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, process 600 includes preventing the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers.

In a second aspect, alone or in combination with the first aspect, preventing the UE from camping on or connecting with the first cell comprises: initiating a timer based at least in part on triggering the RLF procedure, and preventing a connection with the first cell during a radio resource control idle mode based at least in part on the timer.

In a third aspect, alone or in combination with one or more of the first and second aspects, preventing the UE from camping on or connecting with the first cell comprises: entering a radio resource control connected mode on a second cell based at least in part on a performed cell search procedure, performing measurements of one or more neighboring cells, identifying a measurement associated with the first cell from the measurements of the one or more neighboring cells, and transmitting a measurement report without the measurement associated with the first cell to a base station of the second cell based at least in part on detecting the jump in PDCP sequence numbers.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the threshold value is determined based at least in part on a configuration of the UE.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, process 600 includes performing a cell search procedure based at least in part on triggering the RLF procedure, and connecting with a second cell based at least in part on performing the cell search procedure.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the first cell is a non-standalone LTE cell that includes an NR PDCP configuration.

Although Fig. 6 shows example blocks of process 600, in some aspects, process 600 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 6. Additionally, or alternatively, two or more of the blocks of process 600 may be performed in parallel.

The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the aspects.

As used herein, the term “component” is intended to be broadly construed as hardware, firmware, and/or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, and/or a combination of hardware and software.

As used herein, satisfying a threshold may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods described herein may be implemented in different forms of hardware, firmware, and/or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and/or methods were described herein without reference to specific software code-it being understood that software and hardware can be designed to implement the systems and/or methods based, at least in part, on the description herein.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various aspects includes each dependent claim in combination with every other claim in the claim set. 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) .

No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more. ” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, and/or the like) , and may be used interchangeably with “one or more. ” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has, ” “have, ” “having, ” and/or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Claims

A method of wireless communication performed by a user equipment (UE) , comprising:

detecting a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell; and

preventing the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers.
The method of claim 1, further comprising:

triggering a radio link failure procedure based at least in part on detecting the jump in PDCP sequence numbers.
The method of claim 1, wherein detecting the jump in PDCP sequence numbers comprises:

receiving a first PDCP packet associated with a first sequence number in a first slot;

receiving a second PDCP packet associated with a second sequence number in a second slot;

comparing the first sequence number to the second sequence number; and

determining that a difference between the first sequence number and the second sequence number satisfies a threshold value.
The method of claim 3, wherein the threshold value is determined based at least in part on a configuration of the UE.
The method of claim 1, further comprising:

performing a cell search procedure based at least in part on triggering a radio link failure procedure; and

connecting with a second cell based at least in part on performing the cell search procedure.
The method of claim 1, wherein preventing the UE from camping on or connecting with the first cell comprises:

initiating a timer based at least in part on triggering a radio link failure procedure; and

preventing a connection with the first cell during a radio resource control idle mode based at least in part on the timer.
The method of claim 1, wherein preventing the UE from camping on or connecting with the first cell comprises:

entering a radio resource control connected mode on a second cell based at least in part on a performed cell search procedure;

performing measurements of one or more neighboring cells;

identifying a measurement associated with the first cell from the measurements of the one or more neighboring cells; and

transmitting a measurement report without the measurement associated with the first cell to a base station of the second cell based at least in part on detecting the jump in PDCP sequence numbers.
The method of claim 1, wherein the first cell is a non-standalone Long Term

Evolution (LTE) cell that includes a New Radio (NR) PDCP configuration.
A method of wireless communication performed by a user equipment (UE) , comprising:

detecting a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell based at least in part on a difference between sequence numbers of the PDCP packets satisfying a threshold value; and

triggering a radio link failure (RLF) procedure based at least in part on detecting the jump in PDCP sequence numbers.
The method of claim 9, further comprising:

preventing the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers.
The method of claim 10, wherein preventing the UE from camping on or connecting with the first cell comprises:

initiating a timer based at least in part on triggering the RLF procedure; and

preventing a connection with the first cell during a radio resource control idle mode based at least in part on the timer.
The method of claim 10, wherein preventing the UE from camping on or connecting with the first cell comprises:

entering a radio resource control connected mode on a second cell based at least in part on a performed cell search procedure;

performing measurements of one or more neighboring cells;

identifying a measurement associated with the first cell from the measurements of the one or more neighboring cells; and

transmitting a measurement report without the measurement associated with the first cell to a base station of the second cell based at least in part on detecting the jump in PDCP sequence numbers.
The method of claim 9, wherein the threshold value is determined based at least in part on a configuration of the UE.
The method of claim 9, further comprising:

performing a cell search procedure based at least in part on triggering the RLF procedure; and

connecting with a second cell based at least in part on performing the cell search procedure.
The method of claim 9, wherein the first cell is a non-standalone Long Term Evolution (LTE) cell that includes a New Radio (NR) PDCP configuration.
A user equipment for wireless communication, comprising:

a memory; and

one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:

detect a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell; and

prevent the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers.
A user equipment for wireless communication, comprising:

a memory; and

one or more processors operatively coupled to the memory, the memory and the one or more processors configured to:

detect a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell based at least in part on a difference between sequence numbers of the PDCP packets satisfying a threshold value; and

trigger a radio link failure procedure based at least in part on detecting the jump in PDCP sequence numbers.
A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:

one or more instructions that, when executed by one or more processors of a user equipment, cause the one or more processors to:

detect a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell; and

prevent the UE from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers.
A non-transitory computer-readable medium storing one or more instructions for wireless communication, the one or more instructions comprising:

one or more instructions that, when executed by one or more processors of a user equipment, cause the one or more processors to:

detect a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell based at least in part on a difference between sequence numbers of the PDCP packets satisfying a threshold value; and

trigger a radio link failure (RLF) procedure based at least in part on detecting the jump in PDCP sequence numbers.
An apparatus for wireless communication, comprising:

means for detecting a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell; and

means for preventing the apparatus from camping on or connecting with the first cell based at least in part on detecting the jump in PDCP sequence numbers.
An apparatus for wireless communication, comprising:

means for detecting a jump in packet data convergence protocol (PDCP) sequence numbers between PDCP packets received from a base station of a first cell based at least in part on a difference between sequence numbers of the PDCP packets satisfying a threshold value; and

means for triggering a radio link failure procedure based at least in part on detecting the jump in PDCP sequence numbers.