WO2018227452A1

WO2018227452A1 - Techniques and apparatuses for user equipment mobility in dual-connectivity mode

Info

Publication number: WO2018227452A1
Application number: PCT/CN2017/088378
Authority: WO
Inventors: Ozcan Ozturk; Huichun LIU; Xipeng Zhu; Gavin Bernard Horn; Luis F.B. LOPES
Original assignee: Qualcomm Incorporated
Priority date: 2017-06-15
Filing date: 2017-06-15
Publication date: 2018-12-20

Abstract

Certain aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may select at least one target node for a radio resource control connection, wherein the user equipment is in a particular radio resource control communication state when the at least one target node is selected, and wherein the user equipment is configured to communicate using dual-connectivity, wherein context information associated with the user equipment is stored by the user equipment, a master node associated with the user equipment, and a secondary node associated with the user equipment based at least in part on the user equipment being in the particular radio resource control communication state; and/or transmit information to the at least one target node or the master node to cause the context information to be provided to the at least one target node. Numerous other aspects are provided.

Description

TECHNIQUES AND APPARATUSES FOR USER EQUIPMENT MOBILITY IN DUAL-CONNECTIVITY MODE

FIELD OF THE DISCLOSURE

Aspects of the present disclosure generally relate to wireless communication, and more particularly to techniques and apparatuses for user equipment (UE) mobility in dual-connectivity mode.

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, etc. ) . 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 UE may communicate with a 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 for wireless communication performed by user equipment may include selecting at least one target node for a radio resource control connection, wherein the user equipment is in a particular radio resource control communication state when the at least one target node is selected, and wherein the user equipment is configured to communicate using dual-connectivity with a master node and a secondary node, wherein context information associated with the user equipment is stored by the user equipment, the master node, and the secondary node based at least in part on the user equipment being in the particular radio resource control communication state； and/or transmitting information to the at least one target node or the first node to cause the context information to be provided to the at least one target node.

In some aspects, a user equipment for wireless communication may include a memory and one or more processors operatively coupled to the memory and configured to select at least one target node for a radio resource control connection, wherein the user equipment is in a particular radio resource control communication state when the at least one target node is selected, and wherein the user equipment is configured to communicate using dual-connectivity with a master node and a secondary node, wherein context information associated with the user equipment is stored by the user equipment, the master node, and the secondary node based at least in part on the user equipment being in the particular radio resource control communication state； and/or transmit information to the at least one target node or the first node to cause the context information to be provided to the at least one target node.

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 user equipment, may cause the one or more processors to select at least one target node for a radio resource control connection, wherein the user equipment is in a particular radio resource control communication state when the at least one target node is selected, and wherein the user equipment is configured to communicate using dual-connectivity with a master node and a secondary node, wherein context information associated with the user equipment is stored by the user equipment, the master node, and the secondary node based at least in part on the user equipment being in the particular radio resource control communication state； and/or transmit information to the at least one target node or the first node to cause the context information to be provided to the at least one target node.

In some aspects, an apparatus for wireless communication may include means for selecting at least one target node for a radio resource control connection, wherein the apparatus is in a particular radio resource control communication state when the at least one target node is selected, and wherein the apparatus is configured to communicate using dual-connectivity with a master node and a secondary node, wherein context information associated with the apparatus is stored by the user equipment, the master node, and the secondary node based at least in part on the apparatus being in the particular radio resource control communication state； and/or means for transmitting information to the at least one target node or the first node to cause the context information to be provided to the at least one target node.

In some aspects, a method for wireless communication to be performed by a first node may include receiving, from a user equipment associated with a dual-connectivity configuration, information relating to the user equipment resuming a radio resource control connection with a wireless network, wherein the user equipment is associated with a particular radio resource control communication state during which the first node stores context information relating to the user equipment, wherein the radio resource control connection is associated with a target master node and a target secondary node； and/or providing the context information, relating to the user equipment, to at least one of the target master node or the target secondary node for establishment of the radio resource control connection.

In some aspects, a first node for wireless communication may include a memory and one or more processors operatively coupled to the memory and configured to receive, from a user equipment associated with a dual-connectivity configuration, information relating to the user equipment resuming a radio resource control connection with a wireless network, wherein the user equipment is associated with a particular radio resource control communication state during which the first node stores context information relating to the user equipment, wherein the radio resource control connection is associated with a target master node and a target secondary node； and/or provide the context information, relating to the user equipment, to at least one of the target master node or the target secondary node for establishment of the radio resource control connection.

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 first node, may cause the one or more processors to receive, from a user equipment associated with a dual-connectivity configuration, information relating to the user equipment resuming a radio resource control connection with a wireless network, wherein the user equipment is associated with a particular radio resource control communication state during which the first node stores context information relating to the user equipment, wherein the radio resource control connection is associated with a target master node and a target secondary node； and/or provide the context information, relating to the user equipment, to at least one of the target master node or the target secondary node for establishment of the radio resource control connection.

In some aspects, an apparatus for wireless communication may include means for receiving, from a user equipment associated with a dual-connectivity configuration, information relating to the user equipment resuming a radio resource control connection with a wireless network, wherein the user equipment is associated with a particular radio resource control communication state during which the apparatus stores context information relating to the user equipment, wherein the radio resource control connection is associated with a target master node and a target secondary node； and/or means for providing the context information, relating to the user equipment, to at least one of the target master node or the target secondary node for establishment of the radio resource control connection.

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

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 purpose of illustration and description, and not as a definition of the limits of the claims.

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 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 certain aspects of the present disclosure.

Fig. 2 shows a block diagram conceptually illustrating an example of a base station in communication with a user equipment (UE) in a wireless communication network, in accordance with certain aspects of the present disclosure.

Fig. 3 is a block diagram conceptually illustrating an example of a frame structure in a wireless communication network, in accordance with certain aspects of the present disclosure.

Fig. 4 is a block diagram conceptually illustrating two example subframe formats with the normal cyclic prefix, in accordance with certain aspects of the present disclosure.

Fig. 5 illustrates an example logical architecture of a distributed radio access network (RAN) , in accordance with certain aspects of the present disclosure.

Fig. 6 illustrates an example physical architecture of a distributed RAN, in accordance with certain aspects of the present disclosure.

Figs. 7A and 7B are diagrams illustrating examples of configuring and entering a radio resource control inactive communication state, in accordance with various aspects of the present disclosure.

Figs. 8A and 8B are diagrams illustrating examples of cell reselection and switching to a radio resource control active connection state, in accordance with various aspects of the present disclosure.

Fig. 9 is a diagram illustrating an example process performed, for example, by a user equipment, in accordance with various aspects of the present disclosure.

Fig. 10 is a diagram illustrating an example process performed, for example, by a node, 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. 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 another aspect. 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, etc. (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.

An access point ( “AP” ) may comprise, be implemented as, or known as NodeB, Radio Network Controller ( “RNC “) , eNodeB (eNB) , Base Station Controller ( “BSC “) , Base Transceiver Station ( “BTS “) , Base Station ( “BS “) , Transceiver Function ( “TF “) , Radio Router, Radio Transceiver, Basic Service Set ( “BSS “) , Extended Service Set ( “ESS “) , Radio Base Station ( “RBS “) , Node B (NB) , gNB, 5G NB, NR BS, Transmit Receive Point (TRP) , or some other terminology.

An access terminal ( “AT” ) may comprise, be implemented as, or be known as an access terminal, a subscriber station, a subscriber unit, a mobile station, a remote station, a remote terminal, a user terminal, a user agent, a user device, user equipment (UE) , a user station, a wireless node, or some other terminology. In some aspects, an access terminal may comprise a cellular telephone, a smart phone, a cordless telephone, a Session Initiation Protocol ( “SIP” ) phone, a wireless local loop ( “WLL” ) station, a personal digital assistant ( “PDA” ) , a tablet, a netbook, a smartbook, an ultrabook, a handheld device having wireless connection capability, a Station ( “STA” ) , or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a cellular phone, a smart phone) , a computer (e.g., a desktop) , a portable communication device, a portable computing device (e.g., a laptop, a personal data assistant, a tablet, a netbook, a smartbook, an ultrabook) , wearable device (e.g., smart watch, smart glasses, smart bracelet, smart wristband, smart ring, smart clothing, etc. ) , medical devices or equipment, biometric sensors/devices, an entertainment device (e.g., music device, video device, satellite radio, gaming device, etc. ) , 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. In some aspects, the node is a wireless node. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered machine-type communication (MTC) UEs, which may include remote devices that may communicate with a base station, another remote device, or some other entity. Machine type communications (MTC) may refer to communication involving at least one remote device on at least one end of the communication and may include forms of data communication which involve one or more entities that do not necessarily need human interaction. MTC UEs may include UEs that are capable of MTC communications with MTC servers and/or other MTC devices through Public Land Mobile Networks (PLMN) , for example. Examples of MTC devices include sensors, meters, location tags, monitors, drones, robots/robotic devices, etc. MTC UEs, as well as other types of UEs, may be implemented as NB-IoT (narrowband internet of things) devices.

It is 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 network 100 in which aspects of the present disclosure may be practiced. The network 100 may be an LTE network or some other wireless network, such as a 5G or NR network. 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, a NR BS, a Node B, a gNB, a 5G NB, an access point, a TRP, etc. 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 examples, 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 examples, the BSs may be interconnected to one another and/or to one or more other BSs or network nodes (not shown) in the access 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, etc.

Wireless network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impact 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, etc. 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, 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 evolved or enhanced machine-type communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, such as sensors, meters, monitors, location tags, etc., 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. 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 Fig. 1, a solid line with double arrows indicates desired transmissions between a UE and a serving BS, which is a BS designated to serve the UE on the downlink and/or uplink. A dashed line with double arrows indicates potentially interfering transmissions between a UE and a BS.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular 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 frequency channel, etc. 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 examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station) allocates resources for communication among some or all devices and equipment within the scheduling entity’s service area or cell. Within the present disclosure, as discussed further below, 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. That is, in some examples, a UE may function as a scheduling entity, scheduling resources for one or more subordinate entities (e.g., one or more other UEs) . In this example, the UE is functioning as a scheduling entity, and other UEs utilize resources scheduled by the UE for wireless communication. 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 optionally communicate directly with one another in addition to communicating with the scheduling entity.

Thus, in a wireless communication network with a scheduled access to time–frequency resources and having a cellular configuration, a P2P configuration, and a mesh configuration, a scheduling entity and one or more subordinate entities may communicate utilizing the scheduled resources.

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

Fig. 2 shows a block diagram of a design 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) , etc. ) and control information (e.g., CQI requests, grants, upper layer signaling, etc. ) 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, etc. ) 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 certain 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, etc. ) 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) , etc.

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, etc. ) 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, etc. ) , 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.

In some aspects, one or more components of UE 120 may be included in a housing. Controllers/

processors

240 and 280 and/or any other component (s) in Fig. 2 may direct the operation at base station 110 and UE 120, respectively, to perform UE mobility in dual-connectivity mode. For example, controller/processor 280 and/or other processors and modules at UE 120, may perform or direct operations of UE 120 to perform UE mobility in dual-connectivity mode. For example, controller/processor 280 and/or other controllers/processors and modules at UE 120 may perform or direct operations of, for example, process 900 of Fig. 9 and/or other processes as described herein. Additionally, or alternatively, controller/processor 240 and/or other processors and modules at base station 110, may perform or direct operations of base station 110 to perform UE mobility in dual-connectivity mode. For example, controller/processor 240 and/or other controllers/processors and modules at base station 110 may perform or direct operations of, for example, process 1000 of Fig. 10 and/or other processes as described herein. In some aspects, one or more of the components shown in Fig. 2 may be employed to perform example process 900, example process 1000, and/or other processes for the techniques described herein.

Memories

242 and 282 may store data and program codes for base station 110 and UE 120, respectively. A scheduler 246 may schedule UEs for data transmission on the downlink and/or uplink.

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

Fig. 3 shows an example frame structure 300 for frequency division duplexing (FDD) in a telecommunications system (e.g., LTE) . The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 milliseconds (ms) ) and may be partitioned into 10 subframes with indices of 0 through 9. Each subframe may include two slots. Each radio frame may thus include 20 slots with indices of 0 through 19. Each slot may include L symbol periods, e.g., seven symbol periods for a normal cyclic prefix (as shown in Fig. 3) or six symbol periods for an extended cyclic prefix. The 2L symbol periods in each subframe may be assigned indices of 0 through 2L–1.

While some techniques are described herein in connection with frames, subframes, slots, and/or the like, these techniques may equally apply to other types of wireless communication structures, which may be referred to using terms other than “frame, ” “subframe, ” “slot, ” and/or the like in 5G NR. In some aspects, a wireless communication structure may refer to a periodic time-bounded communication unit defined by a wireless communication standard and/or protocol.

In certain telecommunications (e.g., LTE) , a BS may transmit a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) on the downlink in the center of the system bandwidth for each cell supported by the BS. The PSS and SSS may be transmitted in

symbol periods

6 and 5, respectively, in

subframes

0 and 5 of each radio frame with the normal cyclic prefix, as shown in Fig. 3. The PSS and SSS may be used by UEs for cell search and acquisition. The BS may transmit a cell-specific reference signal (CRS) across the system bandwidth for each cell supported by the BS. The CRS may be transmitted in certain symbol periods of each subframe and may be used by the UEs to perform channel estimation, channel quality measurement, and/or other functions. The BS may also transmit a physical broadcast channel (PBCH) in symbol periods 0 to 3 in slot 1 of certain radio frames. The PBCH may carry some system information. The BS may transmit other system information such as system information blocks (SIBs) on a physical downlink shared channel (PDSCH) in certain subframes. The BS may transmit control information/data on a physical downlink control channel (PDCCH) in the first B symbol periods of a subframe, where B may be configurable for each subframe. The BS may transmit traffic data and/or other data on the PDSCH in the remaining symbol periods of each subframe.

In other systems (e.g., such NR or 5G systems) , a Node B may transmit these or other signals in these locations or in different locations of the subframe.

As indicated above, Fig. 3 is provided merely as an example. Other examples are possible and may differ from what was described with regard to Fig. 3.

Fig. 4 shows two example subframe formats 410 and 420 with the normal cyclic prefix. The available time frequency resources may be partitioned into resource blocks. Each resource block may cover 12 subcarriers in one slot and may include a number of resource elements. Each resource element may cover one subcarrier in one symbol period and may be used to send one modulation symbol, which may be a real or complex value.

Subframe format 410 may be used for two antennas. A CRS may be transmitted from

antennas

0 and 1 in

symbol periods

0, 4, 7, and 11. A reference signal is a signal that is known a priori by a transmitter and a receiver and may also be referred to as a pilot signal. A CRS is a reference signal that is specific for a cell, e.g., generated based at least in part on a cell identity (ID) . In Fig. 4, for a given resource element with label Ra, a modulation symbol may be transmitted on that resource element from antenna a, and no modulation symbols may be transmitted on that resource element from other antennas. Subframe format 420 may be used with four antennas. A CRS may be transmitted from

antennas

0 and 1 in

symbol periods

0, 4, 7, and 11 and from

antennas

2 and 3 in

symbol periods

1 and 8. For both

subframe formats

410 and 420, a CRS may be transmitted on evenly spaced subcarriers, which may be determined based at least in part on cell ID. CRSs may be transmitted on the same or different subcarriers, depending on their cell IDs. For both

subframe formats

410 and 420, resource elements not used for the CRS may be used to transmit data (e.g., traffic data, control data, and/or other data) .

The PSS, SSS, CRS and PBCH in LTE are described in 3GPP TS 36.211, entitled "Evolved Universal Terrestrial Radio Access (E-UTRA) ； Physical Channels and Modulation, " which is publicly available.

An interlace structure may be used for each of the downlink and uplink for FDD in certain telecommunications systems (e.g., LTE) . For example, Q interlaces with indices of 0 through Q –1 may be defined, where Q may be equal to 4, 6, 8, 10, or some other value. Each interlace may include subframes that are spaced apart by Q frames. In particular, interlace q may include subframes q, q + Q, q + 2Q, etc., where q ∈ {0, …, Q-1} .

The wireless network may support hybrid automatic retransmission request (HARQ) for data transmission on the downlink and uplink. For HARQ, a transmitter (e.g., a BS) may send one or more transmissions of a packet until the packet is decoded correctly by a receiver (e.g., a UE) or some other termination condition is encountered. For synchronous HARQ, all transmissions of the packet may be sent in subframes of a single interlace. For asynchronous HARQ, each transmission of the packet may be sent in any subframe.

A UE may be located within the coverage of multiple BSs. One of these BSs may be selected to serve the UE. The serving BS may be selected based at least in part on various criteria such as received signal strength, received signal quality, path loss, and/or the like. Received signal quality may be quantified by a signal-to-noise-and-interference ratio (SINR) , or a reference signal received quality (RSRQ) , or some other metric. The UE may operate in a dominant interference scenario in which the UE may observe high interference from one or more interfering BSs.

While aspects of the examples described herein may be associated with LTE technologies, aspects of the present disclosure may be applicable with other wireless communication systems, such as NR or 5G technologies.

New radio (NR) may refer to radios configured to operate according to a new air interface (e.g., other than Orthogonal Frequency Divisional Multiple Access (OFDMA) -based air interfaces) or fixed transport layer (e.g., other than Internet Protocol (IP) ) . In aspects, NR may utilize OFDM with a CP (herein referred to as cyclic prefix OFDM or CP-OFDM) and/or SC-FDM on the uplink, may utilize CP-OFDM on the downlink and include support for half-duplex operation using time division duplexing (TDD) . In aspects, NR may, for example, utilize OFDM with a CP (herein referred to as CP-OFDM) and/or discrete Fourier transform spread orthogonal frequency-division multiplexing (DFT-s-OFDM) on the uplink, may utilize CP-OFDM on the downlink and include support for half-duplex operation using TDD. NR may include Enhanced Mobile Broadband (eMBB) service targeting wide bandwidth (e.g., 80 megahertz (MHz) and beyond) , millimeter wave (mmW) targeting high carrier frequency (e.g., 60 gigahertz (GHz) ) , massive MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra reliable low latency communications (URLLC) service.

A single component carrier bandwidth of 100 MHZ may be supported. NR resource blocks may span 12 sub-carriers with a sub-carrier bandwidth of 75 kilohertz (kHz) over a 0.1 ms duration. Each radio frame may include 50 subframes with a length of 10 ms. Consequently, each subframe may have a length of 0.2 ms. Each subframe may indicate a link direction (e.g., DL or UL) for data transmission and the link direction for each subframe may be dynamically switched. Each subframe may include DL/UL data as well as DL/UL control data.

Beamforming may be supported 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. Alternatively, NR may support a different air interface, other than an OFDM-based interface. NR networks may include entities such central units or distributed units.

The RAN may include a central unit (CU) and distributed units (DUs) . A NR BS (e.g., gNB, 5G Node B, Node B, transmit receive point (TRP) , access point (AP)) may correspond to one or multiple BSs. NR cells can be configured as access cells (ACells) or data only cells (DCells) . For example, the RAN (e.g., a central unit or distributed unit) can configure the cells. DCells may be cells used for carrier aggregation or dual-connectivity, but not used for initial access, cell selection/reselection, or handover. In some cases, DCells may not transmit synchronization signals—in some case cases DCells may transmit SS. NR BSs may transmit downlink signals to UEs indicating the cell type. Based at least in part on the cell type indication, the UE may communicate with the NR BS. For example, the UE may determine NR BSs to consider for cell selection, access, handover, and/or measurement based at least in part on the indicated cell type.

As indicated above, Fig. 4 is provided merely as an example. Other examples are possible and may differ from what was described with regard to Fig. 4.

Fig. 5 illustrates an example logical architecture of a distributed RAN 500, according to aspects of the present disclosure. A 5G access node 506 may include an access node controller (ANC) 502. The ANC may be a central unit (CU) of the distributed RAN 500. The backhaul interface to the next generation core network (NG-CN) 504 may terminate at the ANC. The backhaul interface to neighboring next generation access nodes (NG-ANs) may terminate at the ANC. The ANC may include one or more TRPs 508 (which may also be referred to as BSs, NR BSs, Node Bs, 5G NBs, APs, gNB, or some other term) . As described above, a TRP may be used interchangeably with “cell. ”

The TRPs 508 may be a distributed unit (DU) . The TRPs may be connected to one ANC (ANC 502) or more than one ANC (not illustrated) . For example, for RAN sharing, radio as a service (RaaS) , and service specific AND deployments, the TRP may be connected to more than one ANC. A TRP may include one or more antenna ports. The TRPs may be configured to individually (e.g., dynamic selection) or jointly (e.g., joint transmission) serve traffic to a UE.

The local architecture of RAN 500 may be used to illustrate fronthaul definition. The architecture may be defined that support fronthauling solutions across different deployment types. For example, the architecture may be based at least in part on transmit network capabilities (e.g., bandwidth, latency, and/or jitter) .

The architecture may share features and/or components with LTE. According to aspects, the next generation AN (NG-AN) 510 may support dual-connectivity with NR. The NG-AN may share a common fronthaul for LTE and NR.

The architecture may enable cooperation between and among TRPs 508. For example, cooperation may be preset within a TRP and/or across TRPs via the ANC 502. According to aspects, no inter-TRP interface may be needed/present.

According to aspects, a dynamic configuration of split logical functions may be present within the architecture of RAN 500. The packet data convergence protocol (PDCP) , radio link control (RLC) , media access control (MAC) protocol may be adaptably placed at the ANC or TRP.

According to certain aspects, a BS may include a central unit (CU) (e.g., ANC 502) and/or one or more distributed units (e.g., one or more TRPs 508) .

As indicated above, Fig. 5 is provided merely as an example. Other examples are possible and may differ from what was described with regard to Fig. 5.

Fig. 6 illustrates an example physical architecture of a distributed RAN 600, according to aspects of the present disclosure. A centralized core network unit (C-CU) 602 may host core network functions. The C-CU may be centrally deployed. C-CU functionality may be offloaded (e.g., to advanced wireless services (AWS) ) , in an effort to handle peak capacity.

A centralized RAN unit (C-RU) 604 may host one or more ANC functions. Optionally, the C-RU may host core network functions locally. The C-RU may have distributed deployment. The C-RU may be closer to the network edge.

A distributed unit (DU) 606 may host one or more TRPs. The DU may be located at edges of the network with radio frequency (RF) functionality.

As indicated above, Fig. 6 is provided merely as an example. Other examples are possible and may differ from what was described with regard to Fig. 6.

A UE may transfer from a first radio resource control (RRC) connection state to a second RRC connection state. For example, the UE may transfer from an RRC connected state to an RRC idle state to improve UE performance and/or network performance, relative to remaining in the RRC connected state when the UE is not to communicate data with the network for a period of time. However, in the RRC idle state, the UE and a node of a network (e.g., a base station) may release configuration information associated with one or more cells, such as a context associated with the UE and/or the node. In this case, resuming communication for a dual-connectivity mode with the network to receive data may result in excessive network traffic. Thus, the UE may transfer from an RRC connected state to a particular type of RRC connection state, which may be termed an RRC inactive state or a light connection state, wherein the UE and/or the network maintains at least a portion of configuration information to enable a reduced amount of network traffic to resume an RRC connection after entering the particular RRC connection state. This portion of configuration information may be termed context information or a UE context.

Dual-connectivity refers to a technique wherein a UE connects to a master cell that handles paging for the UE, as well as a secondary cell. Dual-connectivity can be used within the same radio access technology (e.g., LTE, NR, etc. ) , or across multiple, different radio access technologies. As one example, some NR deployments may use an LTE node as a master node, and may use an NR node as a secondary node.

A UE in RRC idle or RRC inactive mode may perform cell reselection to select an appropriate cell for an RRC connection when entering RRC active mode (e.g., when the UE has moved from coverage of one cell to coverage of another cell) . However, cell reselection for UEs in RRC inactive mode may present certain difficulties, especially for dual-connectivity UEs. For example, for a dual-connectivity UE, a target master node and a target secondary node may access context information for the UE to facilitate switching to RRC active mode. However, the context information may not be stored by the target master node and/or the target secondary node when the target master node and/or the target secondary node are different than an original or camped master node and/or secondary node of the UE. Also, the UE may be associated with one or more existing connections or configurations with a secondary node, such as a secondary carrier group (SCG) and/or the like. When the UE selects a new secondary carrier, it may be necessary to reconfigure the one or more existing connections or configurations.

Some techniques and apparatuses, described herein, provide distribution of context information to target nodes associated with cell reselection by a UE in an RRC inactive mode, as well as various other aspects relating to mobility by a UE in an RRC inactive mode. For example, some techniques and apparatuses described herein provide configuration or teardown of backhaul interfaces (e.g., an X2 interface, an Xn interface, and/or the like) between master nodes and secondary nodes associated with the UE. Additionally, or alternatively, some techniques and apparatuses described herein provide signaling between a master node and a secondary node to cause the UE to enter the RRC inactive mode. In this way, handling of mobility aspects of an RRC inactive UE associated with dual-connectivity is improved, thereby reducing delay associated with entering an RRC active mode, conserving network resources, and improving user experience.

Figs. 7A and 7B are diagrams illustrating examples 700 of configuring and entering a radio resource control inactive communication state, in accordance with various aspects of the present disclosure. Figs. 7A and 7B show a master node BS 110 and a secondary node BS 110 (e.g., BS 110 of Fig. 1 and/or the like) , which are referred to in the discussion of Figs. 7A and 7B as a master node and a secondary node. For example, the UE 120 shown in Figs. 7A and 7B may be associated with the master node and the secondary node based at least in part on a dual-connectivity configuration of the UE 120. In some aspects, the master node may handle paging, RRC state transfers, and/or context information transfers regarding the UE 120, and the secondary node may be used for data transfer and/or the like.

As shown in Fig. 7A, and by reference number 702, the master node may determine that the UE 120 is to switch to an RRC inactive state. For example, the master node may perform such a determination based at least in part on configuration information associated with the UE 120, scheduling information associated with the UE 120, and/or the like. In some aspects, the master node may determine that the UE 120 is to switch to the RRC inactive state from an RRC connected state or an RRC active state.

As shown by reference number 704, the master node and the secondary node may perform a request and confirmation associated with the RRC inactive state switch. For example, the master node may transmit a request to the secondary node to switch the UE 120 to an RRC inactive communication state, and the secondary node may accept or confirm the request. In some aspects, the secondary node may reject the request (e.g., when the secondary node has data to transmit to the UE 120) . In some aspects, the secondary node may transmit the request to the master node (rather than the master node sending the request to the secondary node) . In such a case, the master node may transmit a confirmation to the secondary node, may reject the request, or may determine that the request is confirmed and configure the UE 120 to enter the RRC inactive state accordingly.

As shown by reference number 706, the master node may transmit an RRC inactive instruction to the UE 120. For example, the master node may configure the UE 120 to enter the RRC inactive state. In some aspects, to configure the UE 120 to enter the RRC inactive state, the master node may terminate one or more interfaces with the core network or another BS 110, may configure a master carrier group (MCG) or secondary carrier group (SCG) of the UE 120, or may perform a similar action.

As shown by reference number 708, in some aspects, the master node may provide information identifying at least one radio access network (RAN) paging area. A RAN paging area may identify a candidate node or cell for cell reselection by the UE 120. Anode of a RAN paging area may be preconfigured to handle transfer of context information associated with the UE 120 without involving the master node, so, by selecting a node of a RAN paging area, the UE 120 may conserve resources of the master node. For example, when the UE 120 selects a cell of a RAN paging area as part of a cell reselection, the UE 120 may not need to notify the master node, which reduces messaging of the UE 120 and conserves network resources. As further shown, the master node provides a master node (shown as MN in Fig. 7A and thereafter) RAN paging area, and provides a secondary node (shown as SN in Fig. 7A and thereafter) paging area. In some aspects, the nodes identified by the RAN paging areas may be nodes associated with an interface (e.g., an X2 interface or Xn interface) with the master node.

As shown by reference number 710, the UE 120 may enter an RRC inactive state based at least in part on the RRC inactive instruction. For example, the UE 120 may cease paging (e.g., may intermittently cease paging) , may power down a radio or one or more other components of the UE 120, and/or the like. As shown by reference number 712, the UE 120 may store context information for the master node and the secondary node based at least in part on entering the RRC inactive communication state. For example, the UE 120 may store information that expedites switching to an RRC connected communication state, such as UE/user identities, a UE mobility state, a security parameter, and/or the like. As shown by reference number 714, the master node and the secondary node may store context information for the UE 120. The context information stored by the master node and the secondary node may include information used to establish an RRC connected communication state with the UE 120, such as information identifying the UE 120, information identifying the master node and/or the secondary node, a security parameter, and/or the like. By storing the context information when the UE 120 is in the RRC inactive state, the UE 120, the master node, and the secondary node reduce delay associated with switching the UE 120 to the RRC connected communication state, thereby improving throughput, network performance, and user experience.

As shown in Fig. 7B, and by reference number 716, the UE 120 may provide an RRC inactive notification to the secondary node. For example, the RRC inactive notification may be provided via a signaling bearer between the UE 120 and the secondary node. In some aspects, the RRC inactive notification may indicate that the UE 120 is in an RRC inactive communication state. In some aspects, the master node may provide the RRC inactive notification to the secondary node (e.g., based at least in part on transmitting the RRC inactive instruction to the UE 120, based at least in part on receiving information from the UE 120 indicating that the UE 120 has entered the RRC inactive state, and/or the like.

As shown by reference number 718, the master node may suspend an interface with the secondary node with regard to the UE 120. For example, the UE 120 may be associated with an X2 or Xn interface between the master node and the secondary node. The master node may suspend the X2 or Xn interface to conserve resources of the master node. An X2 interface may be used when the master node is an eNB (e.g., associated with an LTE network) and an Xn interface may be used when the master node is a gNB (e.g., associated with a 5G or NR network) . Techniques and apparatuses described herein are applicable in scenarios wherein both nodes are associated with an LTE network, wherein both nodes are associated with a 5G network, and wherein one node is associated with an LTE network and one node is associated with a 5G network.

As indicated above, Figs. 7A and 7B are provided as examples. Other examples are possible and may differ from what was described with respect to Figs. 7A and 7B.

Figs. 8A and 8B are diagrams illustrating examples of cell reselection and switching to a radio resource control active connection state, in accordance with various aspects of the present disclosure. Fig. 8A shows an anchor master node and a target master node (e.g., BSs 110) , as well as an anchor secondary node and a target secondary node (e.g., BSs 110) . The anchor master node and anchor secondary node may be nodes which store context information for a UE 120 shown in Fig. 8A. For example, the UE 120 may have previously connected to the anchor master node and the anchor secondary node, so the anchor master node and the anchor secondary node may have previously stored context information regarding the UE 120. For the purpose of Figs. 8A and 8B, assume that the operations described in connection with Figs. 7A and 7B have been performed.

As shown by reference number 802, the UE 120 may select the target master node and the target secondary node based at least in part on RAN paging areas associated with the UE 120. As used herein, selecting refers to the process of cell reselection performed by the UE 120. For example, when in RRC idle or RRC inactive mode, the UE 120 may select a target node based at least in part on one or more criteria. The target node may be the same as an anchor node of the UE 120, or may be different than an anchor node of the UE 120. If the UE 120 initiates an RRC connected mode or an RRC connection, the UE 120 may connect to a most recently selected target node. In Fig. 8A, the UE 120 initiates an RRC connection with a target master node that is different than an anchor master node of the UE 120, and with a target secondary node that is different than an anchor secondary node of the UE 120. In this case, context information and/or other information may need to be exchanged between the target nodes, the anchor nodes, and/or the UE 120.

In some aspects, the UE 120 may select the target node from a set of nodes of a RAN paging area of nodes. A node of a RAN paging area may be preconfigured to handle transfer of context information associated with the UE without involving the master node, so, by selecting a node of a RAN paging area, the UE 120 may conserve resources of the master node. Additionally, or alternatively, the UE 120 may select the target node from a subset of nodes of a RAN paging area (e.g., fewer than all nodes of the RAN paging area) . Additionally, or alternatively, the UE 120 may select the target node from a set of nodes other than nodes of a RAN paging area of the UE 120. The target node referred to in this paragraph may be the target master node and/or the target secondary node. Additionally, or alternatively, the UE 120 may select the target master node from a first RAN paging area (e.g., a RAN paging area for master nodes) and may select the target secondary node from a second RAN paging area (e.g., a RAN paging area for secondary nodes) .

As shown by reference number 804, the UE 120 may provide a resume message to at least one of the target master node, the anchor master node, and/or the anchor secondary node. In some aspects, the UE 120 may provide the resume message to the target secondary node. As further shown, the resume message may identify at least one of the target master node or the target secondary node. For example, the UE 120 may provide a resume message to the target master node identifying the target secondary node. Additionally, or alternatively, the UE 120 may provide a resume message to the target master node identifying the anchor master node (e.g., to facilitate acquisition of the context information) . Additionally, or alternatively, the UE 120 may provide a resume message to the anchor master node identifying the target master node (e.g., to facilitate provision of the context information to the target master node) . Additionally, or alternatively, the UE 120 may provide a resume message to the anchor secondary node (e.g., to facilitate provision of buffered data and/or context information to the target secondary node) .

As shown by reference number 806, the anchor master node may suspend a connection with the anchor secondary node. For example, the anchor master node may suspend an X2 or Xn interface, a bearer, and/or the like with the anchor secondary node. As shown by reference number 808, the anchor master node may provide context information for the UE 120 to the target master node. For example, the anchor master node may identify the target master node based at least in part on the resume message, and may provide the context information accordingly. In some aspects, the anchor master node may provide the context information to the target master node based at least in part on a request from the target master node. In some aspects (e.g., when there is no X2 or Xn interface with the anchor master node) , the target master node may obtain the context information from the core network.

As shown by reference number 810, the anchor secondary node may provide context information for the UE 120 to the target secondary node. For example, the anchor secondary node may identify the target secondary node based at least in part on the resume message, and may provide the context information accordingly. In some aspects, the anchor secondary node may provide the context information to the target secondary node based at least in part on a request from the target secondary node. Additionally, or alternatively, the anchor secondary node may provide the context information to the target master node or the anchor master node for provision to the target secondary node. In some aspects (e.g., when there is no X2 or Xn interface with the anchor secondary node) , the target secondary node may obtain the context information from the core network.

As shown by reference number 812, the target master node may establish a connection with the target secondary node. For example, the target master node may identify the target secondary node based at least in part on the resume message, and may establish an X2 or Xn interface with the target secondary node. As shown by reference number 814, the UE 120 may resume an RRC connection with the target master node and the target secondary node. For example, the UE 120, the target master node, and the target secondary node may establish an RRC connection using the context information, which may be quicker than establishing an RRC connection without the context information. In this way, the anchor master node and the target master node facilitate provision of context information for UE 120 when the UE 120 is resuming an RRC connection with the target master node and the target secondary node.

Fig. 8B is an example wherein a UE 120 has selected a target master node and a target secondary node, wherein the target master node is a same node as the anchor master node and the target secondary node is a different node than the anchor secondary node. Since the target master node is the anchor master node in Fig. 8B, the target master node is simply referred to as the master node.

As shown by reference number 816, the UE 120 may identify the master node and the target secondary node using at least one RAN paging area, as described in more detail in connection with Fig. 8A, above.

As shown by reference number 818, the UE 120 may transmit, to the master node, a resume message identifying the target secondary node. Here, the resume message need not identify the anchor secondary node, since the master node is associated with a connection to the anchor secondary node based at least in part on having established a connection with the UE 120 and the anchor secondary node in accordance with a dual-connectivity configuration of the UE 120.

As shown by reference number 820, the master node may configure at least one of a connection, a context transfer, and/or a buffered data transfer. The master node may configure the connection, the context transfer, and/or the buffered data transfer with the anchor secondary node and/or the target secondary node, as described below.

As shown by reference number 822, the anchor secondary node may provide buffered data to the master node (e.g., based at least in part on a request for the buffered data from the master node) . For example, the buffered data may be downlink data for the UE 120. The anchor secondary node may provide the buffered data to be forwarded to the UE 120 via the master node. In some aspects, the anchor secondary node may provide the buffered data to the target secondary node (rather than to the master node) . For example, in a case wherein the anchor secondary node knows an identity of the target secondary node (e.g., based at least in part on a resume message and/or the like) , the anchor secondary node may provide the buffered data to the target secondary node.

As shown by reference number 824, the master node may establish a connection with the target secondary node. For example, when the master node is not associated with an X2 or Xn interface with the target secondary node, the master node may establish such an interface with the target secondary node. In some aspects, the master node may configure a carrier group with regard to the target secondary node. For example, the master node may change an SCG split bearer to an SCG bearer or an MCG bearer if the target secondary node does not support SCG split bearers. In some aspects, the UE 120 may drop or flush an SCG based at least in part on moving from the anchor secondary node to the target secondary node. In some aspects, the master node may release or suspend a connection or interface with the anchor secondary node for the UE 120 (e.g., based at least in part on establishing a connection with the target secondary node for the UE 120) .

As shown by reference number 826, the master node may provide an identifier of the anchor secondary node to the target secondary node. For example, the target secondary node may use the identifier to obtain context information from the anchor secondary node. As shown by reference number 828, the master node may provide the buffered data of the anchor secondary node to the target secondary node. For example, the master node may provide the buffered data in a case where the anchor secondary node does not provide the buffered data to the target secondary node (e.g., in a case where the anchor secondary node does not know the identity of the target secondary node) . As shown by reference number 830, the anchor secondary node may provide the context information to the target secondary node.

As indicated above, Figs. 8A and 8B are provided as examples. Other examples are possible and may differ from what was described with respect to Figs. 8A and 8B.

Fig. 9 is a diagram illustrating an example process 900 performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process 900 is an example where a UE (e.g., UE 120) performs mobility operations for a dual-connectivity UE.

As shown in Fig. 9, in some aspects, process 900 may include selecting at least one target node for a radio resource control connection (block 910) . For example, the UE may select at least one target node for an RRC connection, as described above. In some aspects, the UE may be in a particular RRC communication state when the at least one target node is selected (e.g., an RRC inactive state) . In some aspects, the UE may be configured to communicate using dual-connectivity with a master node and a secondary node, wherein context information associated with the UE is stored by the UE, the master node associated with the UE, and the secondary node associated with the UE based at least in part on the UE being in the particular radio resource control communication state.

As shown in Fig. 9, in some aspects, process 900 may include transmitting information to the at least one target node or a master node to cause context information to be provided to the at least one target node (block 920) . For example, the UE may transmit information to the at least one target node or a master node (e.g., an anchor master node or target master node) to cause context information (e.g., context information associated with the UE) to be provided to the at least one target node.

In some aspects, the at least one target node is a new secondary node with regard to the dual connectivity configuration of the user equipment, and the UE may send an identifier of the new secondary node to the master node to cause the context information to be provided to the at least one target node. In some aspects, the at least one target node is a new secondary node with regard to the dual connectivity configuration of the user equipment, and is selected from a set of nodes associated with a radio access network (RAN) paging area of the user equipment, and the transmitting of the information to the at least one target node causes a context fetch of the context information by the new secondary node from the secondary node.

In some aspects, the at least one target node is selected from a subset of nodes associated with a radio access network (RAN) paging area of the user equipment. In some aspects, the at least one target node is not included in a set of nodes associated with a radio access network (RAN) paging area of the user equipment. In some aspects, the at least one target node is a new master node with regard to the dual connectivity configuration of the user equipment. In some aspects, the at least one target node includes a new master node and a new secondary node with regard to the dual connectivity configuration of the user equipment. In some aspects, the user equipment is configured to reselect to the new master node and to reselect to the new secondary node from the master node and the secondary node, respectively.

In some aspects, prior to the selection of the at least one target node, the user equipment enters the particular radio resource control communication state based at least in part on a command from the master node. In some aspects, the UE may transmit a notification to the secondary node after the user equipment enters the particular radio resource control communication state.

In some aspects, the user equipment is configured to release a secondary carrier group (SCG) associated with the secondary node based at least in part on establishing the radio resource control connection with the at least one target node which is different than the master node. In some aspects, the user equipment is configured to release a secondary carrier group (SCG) associated with the secondary node based at least in part on a channel quality associated with the secondary node. In some aspects, the user equipment is configured to release the SCG based at least in part on a threshold specified by the master node. In some aspects, the particular radio resource control communication state includes at least one of an inactive state or a light communication state. In some aspects, the user equipment is configured to send information identifying the at least one target node to the master node.

In some aspects, the at least one target node is a new secondary node, and wherein the information identifying the at least one target node is sent upon connection reestablishment. In some aspects, the information identifying the at least one target node further includes a channel quality measurement for the at least one target node. In some aspects, the at least one target node is a same node as the secondary node based at least in part on a channel quality measurement associated with the secondary node.

Although Fig. 9 shows example blocks of process 900, in some aspects, process 900 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 9. Additionally, or alternatively, two or more of the blocks of process 900 may be performed in parallel.

Fig. 10 is a diagram illustrating an example process 900 performed, for example, by a first node, in accordance with various aspects of the present disclosure. Example process 900 is an example where a first node (e.g., BS 110) performs mobility operations for a dual-connectivity UE. In some aspects, the first node may be a master node BS 110. For example, the first node may be an anchor master node BS 110 or a target master node BS 110.

As shown in Fig. 10, in some aspects, process 1000 may include receiving information relating to a user equipment resuming a radio resource control connection with a wireless network, wherein the user equipment is associated with a particular radio resource control communication state during which the first node stores context information relating to the user equipment, and wherein the radio resource control connection is associated with a target master node and a target secondary node (block 1010) . For example, the first node may receive information relating to a UE resuming an RRC connection with a wireless connection. The UE may be in a particular RRC communication state, such as an RRC inactive state. During the RRC inactive state, the first node may store context information relating to the UE. The RRC connection may be associated with a target master node and a target secondary node, at least one of which may be the same as the first node, or all of which may be different than the first node.

As shown in Fig. 10, in some aspects, process 1000 may include providing the context information, relating to the user equipment, to at least one of the target master node or the target secondary node for establishment of the radio resource control connection (block 1020) . For example, the first node may provide the context information to at least one of the target master node or the target secondary node for establishment of the RRC connection. Thus, the first node facilitates more expedient and simpler RRC connection setup for a UE that is in an RRC inactive state and associated with context information.

In some aspects, the first node may configure a radio bearer associated with the user equipment based at least in part on a configuration of the target master node or the target secondary node. In some aspects, the first node is a master node of the user equipment to which the user equipment connected prior to the user equipment connecting to the target master node. In some aspects, the first node may receive information indicating a backhaul connection has been configured between the target master node and the target secondary node. In some aspects, the first node is configured to release a backhaul connection with a particular secondary node of the user equipment to which the user equipment is connected when the information identifying the target secondary node is received. In some aspects, the first node may provide information identifying the target secondary node to a particular secondary node to which the user equipment is connected or has previously been connected, to cause the particular secondary node to provide the context information or buffered data stored by the particular secondary node. In some aspects, the first node is the target master node. In some aspects, the first node is configured to provide an instruction to cause the user equipment to enter the particular radio resource control communication state.

In some aspects, the first node is configured to suspend an interface between the first node and a secondary node of the user equipment while the user equipment is in the particular radio resource control communication state. In some aspects, the first node is configured to provide the instruction based at least in part on a confirmation from a secondary node of the user equipment that the instruction is to be provided. In some aspects, the first node is configured to provide information to a secondary node that the user equipment has entered the particular radio resource control communication state.

In some aspects, the first node is configured to identify a set of nodes of a radio access network (RAN) paging area associated with the user equipment, the set of nodes including at least one of the target master node or the target secondary node. In some aspects, the first node is configured to provide information identifying the set of nodes to the user equipment. In some aspects, the target master node is selected from a first set of nodes of a first radio access network (RAN) paging area and the target secondary node is selected from a second set of nodes of a second RAN paging area. In some aspects, the particular radio resource control communication state includes at least one of an inactive state or a light communication state. In some aspects, the first node may receive information identifying the target secondary node, wherein the first node is configured to provide the context information to the target secondary node based at least in part on receiving the information identifying the target secondary node. In some aspects, the first node may receive information identifying the target secondary node, wherein the first node is configured to provide the information identifying the target secondary node to a secondary node with which the user equipment was previously connected.

Although Fig. 10 shows example blocks of process 1000, in some aspects, process 1000 may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in Fig. 10. Additionally, or alternatively, two or more of the blocks of process 1000 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 are possible 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, or a combination of hardware and software. As used herein, a processor is implemented in hardware, firmware, or a combination of hardware and software.

Some aspects are described herein in connection with thresholds. As used herein, satisfying a threshold may 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, 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 possible 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 possible 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, etc. ) , and may be used interchangeably with “one or more. ” Where only one item is intended, the term “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, comprising:

selecting at least one target node for a radio resource control connection, wherein the user equipment is in a particular radio resource control

communication state when the at least one target node is selected； and wherein the user equipment is configured to communicate using dual

connectivity with a master node and a secondary node,

wherein context information associated with the user equipment is stored by the user equipment, the master node, and the secondary node based at least in part on the user equipment being in the particular radio resource control communication state； and

transmitting, by the user equipment, information to the at least one target node or the master node to cause the context information to be provided to the at least one target node.
The method of claim 1, wherein the at least one target node is a new secondary node with regard to a dual connectivity configuration of the user equipment； and

wherein the method further comprises sending an identifier of the new secondary node to the master node to cause the context information to be provided to the at least one target node.
The method of claim 1, wherein the at least one target node is a new secondary node with regard to a dual connectivity configuration of the user equipment, and is selected from a set of nodes associated with a radio access network (RAN) paging area of the user equipment； and

wherein the transmitting of the information to the at least one target node causes a context fetch of the context information by the new secondary node from the secondary node.
The method of claim 1, wherein the at least one target node is selected from a subset of nodes associated with a radio access network (RAN) paging area of the user equipment.
The method of claim 1, wherein the at least one target node is not included in a set of nodes associated with a radio access network (RAN) paging area of the user equipment.
The method of claim 1, wherein the at least one target node is a new master node with regard to a dual connectivity configuration of the user equipment.
The method of claim 1, wherein the at least one target node includes a new master node and a new secondary node with regard to a dual connectivity configuration of the user equipment.
The method of claim 7, wherein the user equipment is configured to reselect to the new master node and to reselect to the new secondary node from the master node and the secondary node, respectively.
The method of claim 1, wherein, prior to the selection of the at least one target node, the user equipment enters the particular radio resource control communication state based at least in part on a command from the master node.
The method of claim 9, further comprising:

transmitting a notification to the secondary node after the user equipment enters the particular radio resource control communication state.
The method of claim 1, wherein the user equipment is configured to release a secondary carrier group (SCG) associated with the secondary node based at least in part on establishing the radio resource control connection with the at least one target node, wherein the at least one target node is different than the master node.
The method of claim 1, wherein the user equipment is configured to release a secondary carrier group (SCG) associated with the secondary node based at least in part on a channel quality associated with the secondary node.
The method of claim 12, wherein the user equipment is configured to release the SCG based at least in part on a threshold specified by the master node.
The method of claim 1, wherein the user equipment is configured to release a secondary carrier group (SCG) associated with the secondary node upon change of a radio access network (RAN) paging area of the user equipment.
The method of claim 1, wherein the particular radio resource control communication state includes at least one of an inactive state or a light communication state.
The method of claim 1, wherein the user equipment is configured to send information identifying the at least one target node to the master node.
The method of claim 16, wherein the at least one target node is a new secondary node, and wherein the information identifying the at least one target node is sent upon connection reestablishment.
The method of claim 17, wherein the information identifying the at least one target node further includes a channel quality measurement for the at least one target node.
The method of claim 1, wherein the at least one target node is a same node as the secondary node based at least in part on a channel quality measurement associated with the secondary node.
A method of wireless communication performed by a first node, comprising:

receiving, from a user equipment associated with a dual-connectivity configuration, information relating to the user equipment resuming a radio resource control connection with a wireless network,

wherein the user equipment is associated with a particular radio resource control communication state during which the first node stores context information relating to the user equipment,

wherein the radio resource control connection is associated with a target master node and a target secondary node； and

providing the context information, relating to the user equipment, to at least one of the target master node or the target secondary node for establishment of the radio resource control connection.
The method of claim 20, further comprising:

configuring a radio bearer associated with the user equipment based at least in part on a configuration of the target master node or the target secondary node.
The method of claim 20, wherein the first node is a master node of the user equipment to which the user equipment connected prior to the user equipment connecting to the target master node.
The method of claim 20, further comprising:

receiving information indicating that a backhaul connection has been configured between the target master node and the target secondary node.
The method of claim 20, wherein the first node is configured to release a backhaul connection with a particular secondary node of the user equipment to which the user equipment is connected when the information identifying the target secondary node is received.
The method of claim 20, further comprising:

providing information identifying the target secondary node to a particular secondary node to which the user equipment is connected or has previously been connected, to cause the particular secondary node to provide the context information or buffered data stored by the particular secondary node.
The method of claim 20, wherein the first node is the target master node.
The method of claim 20, wherein the first node is configured to provide an instruction to cause the user equipment to enter the particular radio resource control communication state.
The method of claim 27, wherein the first node is configured to suspend an interface between the first node and a secondary node of the user equipment while the user equipment is in the particular radio resource control communication state.
The method of claim 27, wherein the first node is configured to provide the instruction based at least in part on a confirmation from a secondary node of the user equipment that the instruction is to be provided.
The method of claim 20, wherein the first node is configured to provide information to a secondary node that the user equipment has entered the particular radio resource control communication state.
The method of claim 20, wherein the first node is configured to identify a set of nodes of a radio access network (RAN) paging area associated with the user equipment, the set of nodes including at least one of the target master node or the target secondary node.
The method of claim 31, wherein the first node is configured to provide information identifying the set of nodes to the user equipment.
The method of claim 20, wherein the target master node is selected from a first set of nodes of a first radio access network (RAN) paging area and the target secondary node is selected from a second set of nodes of a second RAN paging area.
The method of claim 20, wherein the particular radio resource control communication state includes at least one of an inactive state or a light communication state.
The method of claim 20, further comprising:

receiving information identifying the target secondary node,

wherein the first node is configured to provide the context information to the target secondary node based at least in part on receiving the information identifying the target secondary node.
The method of claim 20, further comprising:

receiving information identifying the target secondary node,

wherein the first node is configured to provide the information identifying the target secondary node to a secondary node with which the user equipment was previously connected.
A method, apparatus, system, computer program product, non-transitory computer-readable medium, node, base station, wireless communication device, and processing system as substantially described herein with reference to and as illustrated by the accompanying drawings and specification.