HK40004883B - Method and apparatus for secondary base station mobility - Google Patents

Description

Method and apparatus for secondary base station mobility

CROSS-REFERENCE TO RELATED APPLICATIONS

No. 62/374,797, filed on August 13, 2016, entitled “Capability Coordination across RATs,” and U.S. Patent Application Serial No. 15/675,540, filed on August 11, 2017, entitled “Method and Apparatus for Secondary Base Station Mobility,” each of which is expressly incorporated herein by reference in its entirety.

Technical Field

The present disclosure generally relates to communication systems, and more particularly, to signaling for dual connectivity.

Background Art

Wireless communication systems are widely deployed to provide a variety of telecommunication services such as telephony, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple access technologies that can support communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at a city level, a national level, a regional level, and even a global level. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continued evolution of mobile broadband announced by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., the Internet of Things (IoT)), and other requirements. Certain aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There is a need for further improvements to 5G NR technology. These improvements may also be applicable to other multiple access technologies and the telecommunication standards that employ them.

Some communication systems may support dual connectivity, for example, a user equipment (UE) may be connected to two base stations (eg, a primary base station and a secondary base station).

Summary of the Invention

The following content presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects and is neither intended to identify key or critical elements of all aspects nor to delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that will be presented later.

As discussed above, some communication systems may support dual connectivity, such as a UE that may be connected to two base stations (e.g., a primary base station and a secondary base station). The systems and methods described herein may be used to support dual connectivity, where the secondary base station executes a radio resource manager (RRM).

In aspects of the present disclosure, methods, computer-readable media, and apparatus are provided. The apparatus may be an apparatus for wireless communication. For example, the apparatus may be a secondary base station configured to: establish a radio link for dual connectivity to a user equipment (UE), wherein the radio link includes a signaling radio bearer (SRB); send a radio resource control (RRC) connection reconfiguration signal to the UE to enable measurement reporting associated with the radio link; receive an RRC connection reconfiguration complete signal from the UE at the secondary base station; and receive a measurement report from the UE associated with the radio link at the secondary base station.

In aspects of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be an apparatus for wireless communication. For example, the apparatus may be a UE configured to: establish a first radio link with a primary base station; establish a second radio link with a first cell associated with a secondary base station, wherein the second radio link includes a signaling radio bearer (SRB); receive a radio resource control (RRC) connection reconfiguration signal from the second radio link SRB to enable measurement reporting associated with the second radio link; and provide a measurement report to the secondary base station associated with the second radio link using the second radio link SRB.

To accomplish the foregoing and related ends, one or more aspects include the features hereinafter fully described and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail certain illustrative features of one or more aspects. However, these features are indicative of but a few of the various ways in which the principles of the various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communication system and an access network.

2A , 2B, 2C, and 2D are diagrams illustrating examples of a DL frame structure, a DL channel within the DL frame structure, a UL frame structure, and a UL channel within the UL frame structure, respectively.

FIG3 is a diagram showing an example of a base station and a user equipment in an access network.

FIG4 is a diagram illustrating a base station in communication with a UE.

FIG5 is a diagram illustrating non-standalone NR signaling in a RAN logical architecture including NR multi-connectivity.

FIG6 is a diagram showing a call flow of establishing a connection with a secondary base station.

FIG. 7 is a diagram illustrating a change in a call flow of a secondary base station.

FIG8 is a diagram illustrating a secondary base station S-NB connection reconfiguration process when UE capacity is updated.

FIG9 is a diagram showing a call flow of establishing a connection with a secondary base station.

FIG10 is a diagram showing a change in a call flow of a secondary base station.

FIG11 is a diagram illustrating a secondary base station connection reconfiguration process when UE capacity is updated.

FIG12 is a diagram illustrating a communication system including a separate SRB RAN protocol architecture.

FIG13 is a diagram showing a call flow of establishing a connection with a secondary base station.

FIG14 is a diagram illustrating a variation of the call flow (option 3) for the secondary base station 504.

FIG15 is a diagram showing an example of secondary/secondary base station reconfiguration when UE capacity is updated.

16 is a flow chart of a method of wireless communication.

17 is a flow chart of a method of wireless communication.

18 is a flow chart of a method of wireless communication.

19 is a flow chart of a method of wireless communication.

20 is a flow chart of a method of wireless communication.

FIG. 21 is a conceptual data flow diagram illustrating the flow of data between different units/components in an exemplary apparatus.

FIG. 22 is a diagram illustrating an example of a hardware implementation of an apparatus employing a processing system.

FIG. 23 is a conceptual data flow diagram illustrating the flow of data between different units/components in an exemplary apparatus.

FIG. 24 is a diagram illustrating an example of a hardware implementation of an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configuration in which the concepts described herein may be practiced. In order to provide a thorough understanding of the various concepts, the detailed description includes specific details. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, to avoid obscuring such concepts, well-known structures and components are shown in block diagram form.

Several aspects of telecommunication systems will now be presented with reference to various apparatuses and methods. These apparatuses and methods will be described in the detailed description that follows and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively, "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

For example, an element, or any part of an element, or any combination of elements can be implemented as a "processing system" comprising one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, system-on-chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic devices, discrete hardware circuits, and other suitable hardware configured to perform the various functions described throughout this disclosure. One or more processors in a processing system can execute software. Software should be broadly interpreted as meaning instructions, instruction sets, data, code, code segments, program codes, programs, programming, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, processes, functions, etc., regardless of whether they are referred to as software, firmware, middleware, microcode, hardware description languages, or other.

Therefore, in one or more example embodiments, the functions described can be implemented in hardware, software, or any combination thereof. If implemented in software, the functions can be stored on one or more instructions or codes on a computer-readable medium or encoded as one or more instructions or codes. Computer-readable media include computer storage media. Storage media can be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, a combination of computer-readable media of the above types, or any other medium that can be used to store computer-executable code in the form of instructions or data structures that a computer can access.

FIG1 is a diagram illustrating an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, and an evolved packet core (EPC) 160. The base station 102 may include a macro cell (a high-power cellular base station) and/or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

Base stations 102 (collectively referred to as the Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) interface with EPC 160 via backhaul links 132 (e.g., an S1 interface). Base stations 102 may perform one or more of the following functions, among other things: user data delivery, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), user and device tracking, RAN information management (RIM), paging, positioning, and transmission of warning messages. Base stations 102 may communicate with each other directly or indirectly (e.g., via EPC 160) via backhaul links 134 (e.g., an X2 interface). Backhaul links 134 may be wired or wireless.

Base stations 102 can communicate wirelessly with UEs 104. Each of base stations 102 can provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102′ can have a coverage area 110′ that overlaps with the coverage area 110 of one or more macro base stations 102. A network that includes both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may provide service to a restricted group known as a closed subscriber group (CSG). The communication link 120 between base station 102 and UE 104 may include uplink (UL) (also known as reverse link) transmissions from UE 104 to base station 102 and/or downlink (DL) (also known as forward link) transmissions from base station 102 to UE 104. The communication link 120 may utilize multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication link may be over one or more carriers. Base station 102/UE 104 can use spectrum with up to Y MHz (e.g., 5, 10, 15, 20, 100 MHz) of bandwidth per carrier, allocated in carrier aggregation for a total of Yx MHz (x component carriers) for transmission in each direction. The carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL). Component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carriers may be referred to as a secondary cell (SCell).

Certain UEs 104 can communicate with each other using device-to-device (D2D) communication links 192. D2D communication links 192 can use DL/UL WWAN spectrum. D2D communication links 192 can use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication can be achieved through various wireless D2D communication systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on IEEE 802.11 standards, LTE, or NR.

The wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 in the 5 GHz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, the STA 152/AP 150 may perform a clear channel assessment (CCA) prior to communication to determine whether the channel is available.

The small cell 102′ can operate in licensed and/or unlicensed spectrum. When operating in the unlicensed spectrum, the small cell 102′ can use NR and use the same 5 GHz unlicensed spectrum used by the Wi-Fi AP 150. The small cell 102′ using NR in the unlicensed spectrum can improve the coverage of the access network and/or increase the capacity of the access network.

gNodeB (gNB) 180 can operate at millimeter wave (mmW) and/or near-mmW frequencies to communicate with UE 104. When operating at mmW or near-mmW frequencies, gNB 180 may be referred to as a mmW base station. Extremely high frequency (EHF) is a portion of the RF spectrum in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and wavelengths between 1 mm and 10 mm. Radio waves in this frequency band may be referred to as mmWaves. Near-mmWaves extend down to frequencies of 3 GHz with a wavelength of 100 mm. Super high frequency (SHF) bands extend between 3 GHz and 30 GHz and are also referred to as centimeter waves. Communications using mmW/near-mmW radio frequency bands have extremely high path loss and short range. mmW base station 180 can utilize beamforming 184 with UE 104 to compensate for the extremely high path loss and short range.

EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. MME 162 may communicate with a Home Subscriber Server (HSS) 174. MME 162 is a control node that handles signaling between UE 104 and EPC 160. Generally, MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets pass through Serving Gateway 166, which itself is connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation and other functions. PDN Gateway 172 and BM-SC 170 are connected to IP Services 176. IP Services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), PS streaming services, and/or other IP services. BM-SC 170 can provide functionality for MBMS user service provisioning and delivery. BM-SC 170 can serve as the entry point for content providers' MBMS transmissions, can be used to authorize and activate MBMS bearer services within the public land mobile network (PLMN), and can be used to schedule MBMS transmissions. MBMS Gateway 168 can be used to distribute MBMS services to base stations 102 belonging to the Multicast Broadcast Single Frequency Network (MBMS) area broadcasting a specific service and can be responsible for session management (start/stop) and collecting eMBMS-related billing information.

A base station may also be referred to as a gNB, a Node B, an evolved Node B (eNB), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), or some other suitable terminology. Base station 102 provides an access point to EPC 160 for UE 104. Examples of UE 104 include a cellular phone, a smartphone, a Session Initiation Protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, an oven, or any other similarly functional device. Some of UE 104 may be referred to as IoT devices (e.g., a parking meter, a gas pump, an oven, a vehicle, etc.). UE 104 may also be referred to as a station, a mobile station, a user station, a mobile unit, a user unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile user station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

Referring again to FIG. 1 , in certain aspects, the base station 180/UE 104 may be configured to determine operation in a multiple connectivity mode, including connections to a primary base station and a secondary base station, and to send/receive a secondary base station configuration (198). The base station 180 may send the secondary base station configuration, and the UE 104 may receive the secondary base station configuration. The base station 180 may be a primary base station or a secondary base station.

Figure 2A is a diagram 200 showing an example of a DL frame structure. Figure 2B is a diagram 230 showing an example of channels within a DL frame structure. Figure 2C is a diagram 250 showing an example of a UL frame structure. Figure 2D is a diagram 280 showing an example of channels within a UL frame structure. Other wireless communication technologies may have different frame structures and/or different channels. A frame (10 ms) may be divided into 10 subframes of equal size. Each subframe may include two consecutive time slots. A resource grid may be used to represent two time slots, each time slot including one or more time-concurrent resource blocks (RBs) (also referred to as physical RBs (PRBs)). The resource grid is divided into multiple resource elements (REs). For a normal cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 7 consecutive symbols in the time domain (for DL, OFDM symbols; for UL, SC-FDMA symbols), for a total of 84 REs. For an extended cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 6 consecutive symbols in the time domain, for a total of 72 REs. The number of bits carried by each RE depends on the modulation scheme.

As shown in Figure 2A, some of the REs carry DL reference (pilot) signals (DL-RS) for channel estimation at the UE. DL-RS may include a cell-specific reference signal (CRS) (sometimes also referred to as a common RS), a UE-specific reference signal (UE-RS), and a channel state information reference signal (CSI-RS). Figure 2A shows CRS for antenna ports 0, 1, 2, and 3 (indicated as R0, R1, R2, and R3, respectively), UE-RS for antenna port 5 (indicated as R5), and CSI-RS for antenna port 15 (indicated as R).

Figure 2B shows an example of various channels within a DL subframe of a frame. The physical control format indicator channel (PCFICH) is within symbol 0 of slot 0 and carries a control format indicator (CFI) that indicates whether the physical downlink control channel (PDCCH) occupies 1, 2, or 3 symbols (Figure 2B shows a PDCCH occupying 3 symbols). The PDCCH carries downlink control information (DCI) within one or more control channel elements (CCEs), each CCE comprising nine RE groups (REGs), and each REG comprising four consecutive REs in an OFDM symbol. The UE can be configured with a UE-specific enhanced PDCCH (ePDCCH) that also carries DCI. The ePDCCH can have 2, 4, or 8 RB pairs (Figure 2B shows two RB pairs, with each subset comprising one RB pair). The Physical Hybrid Automatic Repeat Request (ARQ) (HARQ) Indicator Channel (PHICH) is also located within symbol 0 of slot 0 and carries the HARQ Indicator (HI), which indicates HARQ acknowledgement (ACK)/negative ACK (NACK) feedback based on the Physical Uplink Shared Channel (PUSCH). The Primary Synchronization Channel (PSCH) may be located within symbol 6 of slot 0 within subframes 0 and 5 of a frame. The PSCH carries the Primary Synchronization Signal (PSS), which the UE 104 uses to determine subframe/symbol timing and physical layer identification. The Secondary Synchronization Channel (SSCH) may be located within symbol 5 of slot 0 within subframes 0 and 5 of a frame. The SSCH carries the Secondary Synchronization Signal (SSS), which the UE uses to determine the physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine the physical cell identifier (PCI). Based on the PCI, the UE can determine the location of the aforementioned DL-RS. The physical broadcast channel (PBCH), which carries the master information block (MIB), can be logically grouped with the PSCH and SSCH to form a synchronization signal (SS) block. The MIB provides a number of RBs within the DL system bandwidth, PHICH configuration, and system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data and broadcast system information not sent via the PBCH, such as the system information block (SIB) and paging messages.

As shown in Figure 2C, some of the REs carry demodulation reference signals (DM-RSs) for channel estimation at the base station. The UE may also send a sounding reference signal (SRS) in the last symbol of the subframe. The SRS may have a comb-like structure, and the UE may send the SRS on one of the multiple comb teeth. The base station may use the SRS for channel quality estimation to implement frequency-dependent scheduling on the UL.

Figure 2D shows an example of various channels within the UL subframe of a frame. The physical random access channel (PRACH) can be within one or more subframes within a frame based on the PRACH configuration. The PRACH can include six consecutive RB pairs within a subframe. The PRACH allows the UE to perform initial system access and achieve UL synchronization. The physical uplink control channel (PUCCH) can be located at the edge of the UL system bandwidth. The PUCCH carries uplink control information (UCI) such as scheduling requests, channel quality indicators (CQI), precoding matrix indicators (PMI), rank indicators (RI), and HARQ ACK/NACK feedback. The PUSCH carries data and can also be used to carry buffer status reports (BSRs), power headroom reports (PHRs), and/or UCI.

FIG3 is a block diagram of a base station 310 communicating with a UE 350 in an access network. In the DL, IP packets from the EPC 160 may be provided to the controller/processor 375. The controller/processor 375 implements layer 3 and layer 2 functions. Layer 3 includes the radio resource control (RRC) layer, and layer 2 includes the packet data convergence protocol (PDCP) layer, the radio link control (RLC) layer, and the medium access control (MAC) layer. The controller/processor 375 provides RRC layer functions associated with broadcasting of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functions associated with header compression/decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; RLC layer functions associated with transmission of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs), resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functions associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

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

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

The controller/processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller/processor 359 provides demultiplexing between transport and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller/processor 359 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

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

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

UL transmissions are processed at the base station 310 in a manner similar to that described in conjunction with the receiver functionality at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to an RX processor 370.

The controller/processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. In the UL, the controller/processor 375 provides demultiplexing between transport and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the UE 350. The IP packets from the controller/processor 375 may be provided to the EPC 160. The controller/processor 375 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

FIG4 is a diagram 400 illustrating a base station 402 in communication with a UE 404. Referring to FIG4 , the base station 402 can transmit beamformed signals to the UE 404 in one or more of directions 402a, 402b, 402c, 402d, 402e, 402f, 402g, and 402h. The UE 404 can receive the beamformed signals from the base station 402 in one or more receive directions 404a, 404b, 404c, and 404d. The UE 404 can also transmit beamformed signals to the base station 402 in one or more of directions 404a-404d. The base station 402 can receive the beamformed signals from the UE 404 in one or more of receive directions 402a-402h. The base station 402/UE 404 can perform beam training to determine the optimal receive and transmit directions for each of the base station 402/UE 404. The transmit and receive directions of the base station 402 may or may not be the same. The transmit and receive directions of the UE 404 may or may not be the same.

FIG5 is a diagram 500 illustrating non-standalone (NSA) NR signaling in a RAN logical architecture including NR multi-connectivity. Diagram 500 includes two base stations 502 and 504, and a UE 506. Base station 502 may be a primary base station 502, such as a master node B (M-NB). Base station 504 may be an auxiliary or secondary base station 504, such as an auxiliary or secondary node B (S-NB).

The primary base station 502 may be coupled to an assisting or secondary base station 504, which allows communication between the primary base station 502 and the assisting or secondary base station 504. For example, the RRC in the primary base station 502 may be coupled to the RRC in the assisting or secondary base station 504.

Diagram 500 also includes a core network (CN) 508. CN 508 can be coupled to a primary base station 502. Thus, primary base station 502 can provide connectivity to the CN, for example, via NG2. Furthermore, auxiliary or secondary base station 502 can provide connectivity to the CN, for example, via RRC in auxiliary or secondary base station 504 to RRC in primary base station 502, and via NG2 between primary base station 502 and CN 508. Thus, UE 506 can communicate with CN 508 via one or more of primary base station 502 and/or auxiliary or secondary base stations 504. For example, UE 506 can operate in dual connectivity to communicate with CN 508 via both primary base station 502 and auxiliary or secondary base station 504.

Dual connectivity can be used in communication systems such as 3GPP-based communication systems. For example, a UE 506 can maintain simultaneous connections to a macrocell base station (MeNB) and a small cell base station (SeNB). Dual connectivity is defined in, for example, TS 36.300.

In one aspect, multi-connectivity (equivalent to dual connectivity in LTE) can be considered, where one of the cells is LTE (e.g., a MeNB) and the other cells are 5G-NR (e.g., a SeNB). Different aspects can vary the device that maintains the radio resource manager (RRM) configuration for a secondary base station (e.g., a secondary Node B (S-NB)). In aspects of the systems and methods described herein, a secondary base station can be used to perform RRM to support mobility.

Some examples may include one or more of three options for communicating the secondary base station configuration to the UE. A first option may utilize secondary base station radio resource control (RRC) over a master cell group (MCG). In aspects where the secondary base station RRC is transmitted over the MCG, the first access service network (ASN.1) of the secondary base station, such as a secondary Node B, may always be transmitted over the MCG radio link. In this aspect, the secondary base station ASN.1 may be the secondary base station information element (IE) "S-NB Configuration IE," and this IE may be piggybacked via the SCG-Configuration IE in the M-NB's RRC message: RRC Connection Reconfiguration (RRC Connection Reconfiguration).

In the second option, the secondary base station RRC message used for initial S-NB connection establishment can be used to establish a secondary base station connection on the MCG. The secondary base station RRC message used for initial S-NB connection establishment can be sent over the MCG radio link. Subsequent NRRRC messages can be sent over the NR Uu.

In a third option, the secondary base station RRC message may be sent via a separate signaling radio bearer (SRB). The UE 506 and the radio access network (RAN) may establish an SRB for each secondary base station (e.g., a Node B (NB)), and the secondary base station RRC message may be delivered via a separate SRB by an MCG SRB or an SCGSRB.

Aspects may be related to secondary base station mobility. In an aspect, on the network side, a method for a mobile network node to support multiple connections for a mobile device with different radio access technologies (RATs) may include: maintaining, at each radio access network node (RAN node), the capacity of the mobile device for the RAT associated with the RAN node, determining radio resource allocation for the mobile device based on the capacity information of the mobile device for the associated RAT, requesting an anchor RAN node to derive a new security key (SK ^* _NB ), and providing the derived key and the corresponding SCG count for the key derivation, so that the secondary RAN node strengthens security to the established radio bearer, and notifying the anchor RAN node of the address of the secondary RAN node so that the anchor RAN node can request the CN node to update the user plane path accordingly.

In an aspect, a method for a mobile network node (including, at each radio access network node (RAN node)) to update a multiple connectivity configuration for a mobile device with different radio access technologies (RATs) may include: updating the capacity of the mobile device for the RAT associated with the RAN node upon receiving UE capacity information sent from the mobile device, and determining a radio resource reallocation for the mobile device (i.e., reducing or increasing the number of serving cells for the mobile device) based on the updated UE capacity information.

In one aspect, the anchor RAN node and the secondary RAN node can be associated with an LTE eNB, an NR NB, or a WLAN WT, and any combination thereof (e.g., LTE eNB+NR NB, NR-NB+LTE eNB, LTE eNB+LTE eNB, NR NB+NR NB, LTEeNB+WLAN WT, NR-NB+WLAN WT, etc.). The anchor RAN node and the secondary RAN node can be associated with an LTE eNB, an NR NB, a WLAN, or other RATs (e.g., GSM, WCDMA, HSPA, WiMax, and any combination thereof). Multiple connections can include two or more connections with any combination of RATs (LTE, NR, WLAN, or even + WCDMA/HSPA, GSM). Reconfiguring a mobile device can be performed using a radio link of an M-NB (MCG radio link), a radio link of an S-NB (SCG radio link), or any combination thereof.

In an aspect, on the UE side, a method for a mobile device to support multiple connections with different radio access technologies (RATs) may include: reporting UE capacity information of the mobile device for each RAT, and reporting the capacity information of the mobile device when one of the UE capacities changes due to reconfiguration of connections to other RATs (e.g., updating NR RF capacity when LTESCell is added, and vice versa).

In an aspect, partitioning the total capacity of a mobile device across supported RATs can be based on user preferences (e.g., prioritizing NR capacity over other RATs, so more capacity is allocated to NR). In an aspect, reorganizing UE capacity information for each RAT upon connectivity change for each RAT can be based on user preferences. In an aspect, reporting UE capability information can be performed using a radio link of an M-NB (MCG radio link), a radio link of an S-NB (SCG radio link), or any combination thereof. In an aspect, reconfiguring a mobile device can be performed using a radio link of an M-NB (MCG radio link), a radio link of an S-NB (SCG radio link), or any combination thereof.

Aspects may be related to the concept of dual connectivity operation. The systems and methods described herein may consider multi-connectivity (equivalent to dual connectivity in LTE), where one cell is LTE (MeNB) and the other cell is NR (S-NB).

In various aspects, it is considered who maintains the RRM configuration of the S-NB. The RAN may maintain the RRM configuration of the UE and may decide to request the secondary NB (S-NB) to provide additional resources (serving cells) for the UE, for example, based on received measurement reports or traffic conditions or bearer types. Options for secondary NB RRM may include: (1) the master NB (M-NB) coordinates with the S-NB to perform RRM for the S-NB, and (2) the secondary NB (S-NB) performs RRM at the S-NB. Table 1 compares the advantages and disadvantages of each option assuming LTE as the primary NB and NR as the secondary NB.

Table 1 Comparison of RRM for S-NB at M-NB or S-NB

In LTE-WLAN aggregation (LWA) (refer to 3GPP 36.300 clause 22A), the WLAN is able to maintain its own mobility, and the UE can move between WLAN APs under the same WLAN terminal (WT). As long as the UE is associated with one of the APs of the WT, LTE forwards packets to the WT, and the WT is responsible for forwarding the data to the appropriate AP. If the UE moves from one WT to another and leaves coverage, the UE performs an LWA WT release procedure and an LWA WT add procedure to re-establish LWA. Therefore, there is no procedure defined for mobility in LWA that allows the UE to move from one WT to another without releasing the old WT and establishing LWA at the new WT. The present invention determines how to perform mobility in these scenarios and is also applicable to scenarios where the secondary NB (S-NB) is another RAT (such as NR).

Figure 6 is a diagram 600 illustrating a call flow for a secondary base station connection establishment. Diagram 600 includes data flows between a UE 506, a master base station (M-NB) 502, a secondary base station 504, a GW 602, and an MME 604. In a first option, NR connection setup can be used. Diagram 600 illustrates Option 1, S-NB RRC on an MCG. Option 1 can use principles such as Release 12 LTE DC operation to provide a reliable connection for secondary base station 504 (S-NB) RRC signaling. Option 1 may perform better when, for example, NR is deployed on mmWave frequencies. The following steps illustrate example call flows for secondary base station 504 (S-NB) connection establishment and secondary base station 504 (S-NB) change scenarios.

In an aspect, the RAB establishment procedure and the security mode command procedure may occur after step 1, however, to simplify the diagram 600, the RAB establishment procedure and the security mode command procedure are omitted in the call flow.

At step 0, the UE 506 performs a PLMN search and camps on a RAT cell associated with the master base station 502 (M-NB).

At step 1, UE 506 establishes an RRC connection with master base station 502 (M-NB). Establishing the RRC connection with master base station 502 (M-NB) may include: an RRC connection request from UE 506 to master base station 502 (step 1), an RRC connection establishment message from master base station 502 to UE 605 (step 1a), and an RRC connection setup complete message from UE 506 to master base station 502 (step 1b).

At step 2 (optional), for example, when the master base station 502 (M-NB) fails to obtain the UE capacity for the UE 506 from the core network entity (e.g., MME), the master base station 502 (M-NB) requests the UE to report the UE capacity (step 2). The UE 506 reports the total UE capacity information including the capacity of the supported RATs to the master base station 502 (M-NB) (step 2a).

In step 3, the master base station 502 (M-NB) configures the UE 506 with the measurement configuration for the RAT associated with the secondary base station 504 (S-NB) (S-NB RAT). The UE 506 then begins measuring the secondary base station 504 (S-NB) RAT accordingly. When certain reporting criteria are met, the UE 506 sends an RRC Connection Reconfiguration Complete message (step 3a) and a Measurement Report message (step 3b) to the master base station 503, including the measured results of the detected cells.

At step 4, the master base station (M-NB) decides to add a secondary connection with the secondary base station 504 (S-NB) based on, for example, the measured results of the cell and the remaining capacity at the master base station 502 (M-NB) and/or the secondary base station 504 (S-NB), which is associated with the reported S-NB RAT cell.

In step 5, the master base station 502 (M-NB) requests the secondary base station 504 (S-NB) to allocate radio resources for a specific E-RAB, indicating E-RAB characteristics (E-RAB parameters, including TNL address information corresponding to the bearer type). Furthermore, the master base station 502 (M-NB) indicates the UE capacity of the RAT associated with the secondary base station 504 (S-NB) within SCG-ConfigInfo. This is used as the basis for reconfiguration by the secondary base station 504 (S-NB), but does not include SCG configuration. Furthermore, the master base station 502 (M-NB) indicates the security key SK ^* _NB used for security enhancement of the secondary base station 504 (S-NB) within SCG-ConfigInfo, as well as the corresponding SCG count used for key derivation.

The master base station 502 (M-NB) may provide the latest measurement results for the SCG cell requested to be added. The secondary base station 504 (S-NB) may reject the request (step 5a).

When the RRM entity in the secondary base station 504 (S-NB) is able to accept the resource request, it allocates corresponding radio resources and allocates corresponding transport network resources according to the bearer option.

FFS may be optional. The secondary base station 504 (S-NB) may trigger random access to enable synchronization of the radio resource configuration of the secondary base station 504 (S-NB).

The secondary base station 504 (S-NB) provides the master base station 502 (M-NB) with the new radio resources for the SCG in the SCG-Config. For SCG bearers, the secondary base station 504 (S-NB) provides the new radio resources for the SCG as well as NG3 DL TNL address information for the corresponding E-RAB and security algorithm, as well as XN/X2 DL TNL address information for the separate bearers.

In contrast to SCG bearers, for the option of separate bearers, the master base station 502 (M-NB) may decide to request such an amount of resources from the secondary base station 504 (S-NB) that the QoS for the corresponding E-RAB is guaranteed by the exact sum of the resources provided by the master base station 502 (M-NB) and the secondary base station 504 (S-NB) together (or even more). The NB decision may be reflected in step 5 through the E-RAB parameters signaled to the secondary base station 504 (S-NB), which may be different from the E-RAB parameters received on S1/NG2.

For a specific E-RAB, the master base station 502 (M-NB) may request to directly establish an SCG or separate bearer, for example, without first establishing an MCG bearer.

In the case of an MCG split bearer, transmission of user plane data may be performed after step 5a. In the case of an SCG bearer or an SCG split bearer, data forwarding and SN state transfer may be performed after step 5a.

At step 6, the master base station 502 (M-NB) sends an RRC Connection Reconfiguration message to the UE 506, including the new radio resource configuration for the SCG according to the SCG-Config. The UE 506 applies the new configuration and replies to the master base station 502 (M-NB) with an RRC Connection Reconfiguration Complete message (RRC Connection Reconfiguration Complete) (step 6b). If the UE 506 cannot comply with the (partial) configuration included in the RRC Connection Reconfiguration message, the UE 506 may perform a reconfiguration failure procedure. The master base station 502 (M-NB) notifies the secondary base station 504 (S-NB) that the UE 506 has successfully completed the reconfiguration procedure (step 6c). FFS may be optional (step 6d). The UE 506 synchronizes to the PScell (S-NB) of the secondary base station 504. The order in which the UE 506 sends the RRC Connection Configuration Complete message and performs the random access procedure to the SCG is undefined. Successful completion of the RRC Connection Reconfiguration procedure does not require a successful RA procedure to the SCG.

At step 7, in the case of SCG bearer or SCG split bearer, and depending on the bearer characteristics of the corresponding E-RAB, the master base station 502 (M-NB) can take measures to minimize service interruption caused by activating dual connectivity (e.g., SN state transfer (step 7), data forwarding (step 7a)).

At step 8, the UP path to the EPC is updated for the SCG bearer. At step 8, the primary base station 502 sends an E-RAB modification indication to the MME 604. At step 8a, the MME 604 sends a bearer modification message to the GW 602 (step 8b). The GW 602 sends an end-market packet to the secondary base station 504, which is routed through the primary base station 502 (step 8b). The MME 604 confirms the RAB modification (step 8c).

7 is a diagram 700 illustrating a change in a call flow for a secondary base station 504. The diagram 700 includes a master base station 502, a UE 506, and a pair of secondary base stations 702 and 704. The diagram also includes a GW 706 and an MME 708.

At step 0, the UE 506 and the network establish dual connectivity with the master base station 502 (M-NB) and the secondary base station 702 (S-NB1).

At step 1, secondary base station 702 (S-NB1) requests primary base station 502 (M-NB) to configure UE 506 with the secondary base station (S-NB)'s measurement configuration, e.g., the RAT (S-NB RAT) associated with secondary base station 702 (S-NB1) (step 1). Consequently, primary base station 502 (M-NB) reconfigures UE 506 with, e.g., secondary base station 504 (S-NB) RAT measurement results from secondary base station 702 (step 1a). When certain reporting criteria are met, UE 506 performs measurements and sends a measurement report message that includes the results of the measurements of the secondary base station 504 (S-NB) RAT cell (step 1c).

At step 2, the master base station 502 (M-NB) determines a change of the secondary base station based on, for example, the measurement results of the secondary base station 504 (S-NB) RAT and the remaining capacity at S-NB1 and/or S-NB2.

In step 3, master base station 502 (M-NB) initiates an S-NB change by requesting the target S-NB, secondary base station 704 (S-NB2), to allocate resources for UE 506 through the S-NB Add Preparation procedure (additional request). Master base station 502 (M-NB) includes the SCG configuration of the old S-NB (S-NB1) and the RAT UE capacity associated with the S-NB in the S-NB Add Request (step 3). The target S-NB, secondary base station 704 (S-NB2), can confirm this (step 3a).

When forwarding is required, the target secondary base station 704 (S-NB2) provides the forwarding address to the primary base station 502 (M-NB). Furthermore, the primary base station 502 (M-NB) indicates the security key SK ^* _NB for target S-NB security enhancement and the corresponding SCG count for key derivation in the SCG-ConfigInfo (step 3b). When resource allocation to the target secondary base station 704 (S-NB2) is successful, the primary base station 502 (M-NB) initiates the release of the source S-NB resources to the UE 506 and the source secondary base station (S-NB) (step 3b). When data forwarding is required, the primary base station 502 (M-NB) provides the data forwarding address to the source secondary base station 702 (S-NB1). Direct or indirect data forwarding is used for SCG bearers. Only indirect data forwarding is used for separate bearers. Receiving the S-NB Release Request message triggers the source S-NB to stop providing user data to the UE 506 and, if appropriate, to initiate data forwarding.

At step 4, master base station 502 (M-NB) triggers UE 506 to apply the new configuration. Master base station 502 (M-NB) indicates the new configuration to UE 506 in an RRC Connection Reconfiguration message (step 4). If UE 506 cannot comply with the (partial) configuration included in the RRC Connection Reconfiguration message, UE 506 performs a reconfiguration failure procedure (step 4c). FFS may be optional (UE 506 synchronizes with the target S-NB (step 4d)). If the RRC Connection Reconfiguration procedure is successful, master base station 502 (M-NB) notifies the target S-NB using an RRC Configuration Complete message (step 4b).

At step 5, data forwarding from the source secondary base station (S-NB) occurs when appropriate. Data forwarding may be initiated as early as when the source S-NB receives an S-NB release request message from the master base station 502 (M-NB).

At step 6, when one of the bearer environments is configured at the source S-NB using the SCG bearer option, a path update is triggered by the master base station 502. The master base station 502 may send an e-RAB modification to the MME 708 (step 6) and an end market group to the secondary base station 704 (step 6b). The MME 708 may respond to the master base station 502 with an acknowledgment (step 6c).

At step 7, upon receiving the UE environment release message, the source secondary base station (S-NB) can release the following resources associated with the UE environment: radio resources and C-plane-related resources. For example, the primary base station can send a UE environment release message to the secondary base station 704 (S-NB1). Any ongoing data forwarding can continue.

8 is a diagram 800 illustrating a secondary base station 504 (S-NB) connection reconfiguration process when UE capacity is updated. Schematic diagram 800 includes a master base station 502 (M-NB), a secondary base station 504 (S-NB), and a UE 506.

At step 0, the UE 506 and the RAN establish connections with the master base station 502 (M-NB) and the secondary base station 504 (S-NB).

At step 1 , the master base station 502 (M-NB) determines the SCell addition and reconfigures the UE 506 with the new CA configuration.

At step 2, the UE 506 updates the UE capacity information of another RAT based on the remaining UE's resources (eg, available RF chains).

At step 3, the UE 506 reports the updated UE capacity information to the secondary base station 504 (S-NB), for example, through the master base station 502 (M-NB) (steps 3, 3a).

At step 4, the secondary base station 504 (S-NB) reallocates resources for the UE 506 based on the updated UE capacity information and determines to reconfigure the UE 506 accordingly.

At step 5, the secondary base station 504 (S-NB) triggers reconfiguration of the SCG link by sending an S-NB Modification Request message including the new SCG configuration to the primary base station 502 (M-NB) (step 5, from S-NB to M-NB). The primary base station 502 (M-NB) forwards the S-NB Modification Request message including the new SCG configuration to the UE 506 (step 5, from M-NB to UE). The UE 506 performs the commanded reconfiguration (step 5a) and sends back a response message after the reconfiguration (step 5b), such as an RRC Connection Reconfiguration Complete. The primary base station 502 (M-NB) confirms the successful completion of the reconfiguration by sending an S-NB Modification Confirm message to the secondary base station 504 (S-NB) (step 5c).

In one aspect, the secondary base station 504 (S-NB) connection establishment can be performed on the MCG. In another aspect, the secondary base station 504 (S-NB) connection establishment can be performed using the same principles as handover. For example, the secondary base station 504 (S-NB) connection can be established similarly to LWA. Using the same principles as handover (e.g., similar to LWA) to establish the secondary base station 504 (S-NB) connection may have advantages. The NR signaling connection can take advantage of NR radio performance (e.g., lower latency), and the impact of the primary base station 502 (M-NB) may be less because LTE may only need to participate in the initial NR connection establishment, and NR C-plane activities will not interrupt the M-NB. Therefore, once the NR connection is established, each RAT can operate completely independently, and mobility management in each RAT can be independent.

FIG9 is a diagram 900 illustrating a call flow for establishing a connection with a secondary base station 504 (S-NB). Diagram 900 includes a primary base station 502, a UE 506, a GW 908, and an MME 510. The RAB establishment process and the security mode command process may occur after step 1, but are omitted from the call flow shown in FIG9 .

At step 0, the UE 506 performs a PLMN search and camps on a RAT cell associated with the master base station 502 (M-NB).

At step 1, UE 506 establishes an RRC connection with the master base station 502 (M-NB).

At step 2 (optional), for example, when the master base station 502 (M-NB) fails to obtain the UE capacity for the UE 506 from the core network entity (e.g., MME), the master base station 502 (M-NB) requests the UE 506 to report the capacity of the UE 506. The UE 506 reports the total UE capacity information to the master base station 502 (M-NB).

At step 3, the master base station 502 (M-NB) configures the UE 506 with the measurement configuration of the RAT (S-NB RAT) associated with the secondary base station 504 (S-NB). The UE 506 then begins secondary base station 504 (S-NB) RAT measurements accordingly. When certain reporting criteria are met, the UE 506 sends a measurement report message that includes the measured results of the detected secondary base station 504 (M-NB) RAT cells.

At step 4, the master base station 502 (M-NB) decides to add a secondary connection with the secondary base station 504 (S-NB), which is associated with the reported cell, based on, for example, the measured results of the cell and the remaining capacity at the master base station 502 (M-NB) and/or the secondary base station 504 (S-NB).

At step 5 , the master base station 502 (M-NB) requests the secondary base station 504 (S-NB) to allocate radio resources for a specific E-RAB, indicating E-RAB characteristics (E-RAB parameters, TNL address information corresponding to the bearer type).

In addition, the master base station 502 (M-NB) indicates the UE capacity of the RAT associated with the secondary base station 504 (S-NB) in SCG-ConfigInfo, which is used as the basis for reconfiguration by the secondary base station 504 (S-NB). In addition, the M-NB indicates the security key SK ^* _NB used for security enhancement of the secondary base station 504 (S-NB) and the corresponding SCG count used for key derivation in SCG-ConfigInfo.

The master base station 502 (M-NB) can provide the latest measurement results for the SCG cell requested to be added. The secondary base station 504 (S-NB) can reject the request.

At step 5a, when the RRM entity in the secondary base station 504 (S-NB) is able to accept the resource request, it allocates corresponding radio resources and allocates corresponding transport network resources according to the bearer option.

FFS may be optional (the secondary base station 504 (S-NB) triggers random access to enable synchronization of the secondary base station 504 (S-NB) radio resource configuration).

The secondary base station 504 (S-NB) provides the master base station 502 (M-NB) with the new radio resources for the SCG in the SCG-Config. For SCG bearers, the secondary base station 504 (S-NB) provides the new radio resources for the SCG as well as NG3 DL TNL address information for the corresponding E-RAB and security algorithm, as well as XN/X2 DL TNL address information for the separate bearers.

In contrast to SCG bearer, for the split bearer option, the master base station 502 (M-NB) may decide to request such an amount of resources from the secondary base station 504 (S-NB) that the QoS for the corresponding E-RAB is guaranteed by the exact sum of the resources provided by the master base station 502 (M-NB) and the secondary base station 504 (S-NB) together (or even more). The NB decision may be reflected in step 5 through the E-RAB parameters signaled to the secondary base station 504 (S-NB), which may be different from the E-RAB parameters received on S1/NG2.

For a specific E-RAB, the master base station 502 (M-NB) may request to directly establish an SCG or separate bearer, that is, without first establishing an MCG bearer.

In case of MCG split bearer, transmission of user plane data may be performed after step 5a.

In the case of an SCG bearer or an SCG-separated bearer, data forwarding and SN state transfer may be performed after step 5a.

At step 6 , the master base station 502 (M-NB) sends an RRC connection reconfiguration message including a new radio resource configuration of the SCG according to the SCG-Config to the UE 506 .

The UE 506 applies the new configuration and replies with an RRC Connection Reconfiguration Complete message. In case the UE 506 cannot comply with the (partial) configuration included in the RRC Connection Reconfiguration message, it performs a Reconfiguration Failure procedure.

Master base station 502 (M-NB) notifies secondary base station 504 (S-NB) that UE 506 has successfully completed the reconfiguration procedure. FFS may be optional (6d). UE 506 synchronizes to the PScell (S-NB) of secondary base station 504. The order in which UE 506 sends the RRC Connection Configuration Complete message to the SCG and performs the random access procedure is undefined. Successful completion of the RRC Connection Reconfiguration procedure does not require a successful RA procedure to the SCG.

At step 7, in the case of SCG bearer or SCG separated bearer, and depending on the bearer characteristics of the corresponding E-RAB, the master base station 502 (M-NB) can take measures to minimize the service interruption caused by activating dual connectivity (data forwarding, SN state transfer).

At step 8, for the SCG bearer, an update of the UP path to the EPC is performed.

Figure 10 is a diagram 1000 illustrating a call flow change between secondary base stations 1002 and 1004. At step 0, UE 506 establishes dual connectivity with the network, including master base station 502 (M-NB) and secondary base station 1002 (S-NB1). At step 1, secondary base station 1002 (S-NB1) reconfigures UE 506 using the measurement configuration for the RAT associated with secondary base station 1002 (S-NB1) (S-NB RAT). For example, secondary base station 1002 (S-NB1) sends an RRC Connection Reconfiguration (Measurement Configuration of the S-NB-Associated RAT) to UE 506 (step 1). UE 506 performs the measurements. UE 506 sends a Reconfiguration Complete (RRC Connection Reconfiguration Complete) to secondary base station 1002 (S-NB1). When certain reporting criteria are met (eg, measurement report of S-NB RAT cell measurement results), UE 506 sends a measurement report message including the measurement results of the S-NB RAT cell to secondary base station 1002 (S-NB1) (step 1b).

At step 2, the secondary base station 1002 (S-NB1) determines a change of the secondary base station based on, for example, measurement results of cells and the remaining capacity of the secondary base station 1002 (S-NB1) and/or the secondary base station 1004 (S-NB2).

At step 3, the secondary base station 1002 (S-NB1) initiates a secondary base station change by requesting the target secondary base station 1004 (S-NB2) to allocate resources to the UE 506 through a handover preparation process.

The secondary base station 1002 (S-NB1) includes the SCG configuration of the old secondary base station 1002 (S-NB1) and the UE 506 capability information currently stored in the secondary base station 1002 (S-NB1) in the handover request.

At step 4, if the allocation of resources to the target secondary base station 1004 (S-NB2) is successful, the secondary base station 1004 (S-NB2) requests the master base station 502 (M-NB) to change the secondary base station to the secondary base station 1004 (S-NB2). The secondary base station 1004 (S-NB2) provides S-NB TNL information (NG3 DL TNL address information for SCG bearers used for each E-RAB, and TNL address information for separate XN/X2 DL bearers). The master base station 502 (M-NB) derives SK ^* _NB with the new SCG count value of the target secondary base station 1004 (S-NB2). The master base station 502 (M-NB) transmits the derived SK ^* _NB and the corresponding SCG count through the secondary base station change request confirmation procedure.

In the case of an MCG split bearer, transmission of user plane data may be performed after step 4. In the case of an SCG bearer or an SCG split bearer, data forwarding and SN state transfer may be performed after step 4.

In step 5, when resources are successfully allocated to the target secondary base station 1004 (S-NB2) and the master base station 502 (M-NB) confirms the secondary base station change, the target secondary base station 1004 (S-NB2) confirms the handover request with a handover request confirmation message. When forwarding is required, the target secondary base station 1004 (S-NB2) provides the forwarding address to the source secondary base station 1002 (S-NB1).

Secondary base station 1002 (S-NB1) then initiates the release of resources to the UE. Direct data forwarding or indirect data forwarding is used for SCG bearers or SCG-split bearers. Receiving the Handover Request Confirm message triggers source secondary base station 1002 (S-NB1) to stop providing user data to UE 506 and, if appropriate, to start data forwarding.

At step 6, the secondary base station 1002 (S-NB1) sends an RRC connection reconfiguration message, for example, directly (e.g., via an SCG SRB) to the UE 506. The UE 506 sends an RRC connection reconfiguration complete message back to the secondary base station 1004 (S-NB2), for example, directly (e.g., via an SCG SRB at the secondary base station 1004 (S-NB2)).

The master base station 502 (M-NB) indicates the new configuration in an RRC connection reconfiguration message to the UE 506. In case the UE 506 cannot comply with the (partial) configuration included in the RRC connection reconfiguration message, the master base station 502 performs a reconfiguration failure procedure.

At step 6c, when the RRC connection reconfiguration process is successful, the master base station 502 (M-NB) is notified that the secondary base station change is successfully completed. For example, the secondary base station 1004 (S-NB2) can send a "change completed" message to the master base station 502 (M-NB).

At step 6d, the UE 506 and the S-NB2 may optionally perform a random access procedure (the UE 506 is synchronized with the target secondary base station 1004 (S-NB2)).

At step 7, data forwarding from the secondary base station 1002 (S-NB1) occurs when appropriate. Data forwarding may be initiated as early as when the secondary base station 1002 (S-NB1) receives a handover request confirm message from the secondary base station 1004 (S-NB2).

At step 8, when one of the bearer environments is configured at the source S-NB using the SCG bearer option or the SCG split bearer option, a path update is triggered by the MeNB.

At step 9, upon receiving the UE context release message, the source base station (Se) can release the following resources associated with the UE context: radio resources and resources associated with the C-plane. Any ongoing data forwarding can continue.

11 is a diagram 1100 illustrating a connection reconfiguration process of a secondary base station 504 (S-NB) when UE capacity is updated. Schematic diagram 1100 includes a master base station 502 (M-NB) and a UE 506.

At step 0, the UE 506 and the RAN establish connections with the master base station 502 (M-NB) and the secondary base station 504 (S-NB).

At step 1 , the master base station 502 (M-NB) determines the SCell addition and reconfigures the UE 506 with the new CA configuration.

At step 2, the UE 506 updates the UE capacity information of another RAT based on the resources (eg, available RF chains) of the remaining UEs.

At step 3, the UE 506 reports the updated UE capacity information (M-NB) to the secondary base station 504 (S-NB).

At step 4, the secondary base station 504 (S-NB) reallocates resources for the UE 506 based on the updated UE 506 capability information, and determines to reconfigure the UE 506 accordingly.

At step 5, the secondary base station 504 (S-NB) reconfigures the SCG link by sending an RRC connection reconfiguration message from the secondary base station 504 (S-NB) SRB to the UE 506 (step 5) (step 5a). The UE 506 performs the commanded reconfiguration and sends back a response message after the reconfiguration, such as RRC connection reconfiguration complete (step 5b).

In one aspect, NR RRC can be sent over a separate SRB. This aspect can utilize the separate bearer concept introduced in Rel-12 LTE DC for user data delivery to signal S-NB RRC messages. This aspect can include one or more advantages of the other aspects described herein. For example, a reliable connection can be used for secondary base station 504 (S-NB) RRC signaling, allowing it to operate efficiently, for example, when the secondary base station 504 (S-NB) is deployed on mmW frequencies. The secondary base station 504 (S-NB) RRC signaling connection can leverage NR radio performance (e.g., lower latency). The impact on the primary base station 502 (M-NB) may be minimal, as LTE only needs to participate in the initial NR connection establishment. Secondary base station 504 (S-NB) C-plane activity does not disrupt the primary base station 502 (M-NB), so once the secondary base station 504 (S-NB) connection is established, each RAT can operate completely independently. Mobility management in each RAT may become independent.

FIG12 is a diagram illustrating a communication system 1200 including a split SRB RAN protocol architecture. The split SRB RAN protocol architecture portion of the communication system 1200 is shown in bold. Upper Layer 2 includes a PDCP entity. Lower Layer 2 includes an RLC entity.

In one aspect, the secondary base station 504 (S-NB) RRC can be transmitted by one of the serving cells in the primary cell group (MCG) or by one of the serving cells in the secondary cell group (SCG). For downlink SRB selection, determining how to select the downlink SRB can be determined by the network implementation. In one aspect, the secondary base station 504 (S-NB) selects the secondary base station 504 (S-NB) MCG-SRB or the secondary base station 504 (S-NB) SCG-SRB based on radio conditions (e.g., based on the CSI, BLER of each link) or the congestion status of each radio link. For example, the secondary base station 504 (S-NB) MCG-SRB can be selected when the MCG radio link reports a better CQI than the SCG radio link and the CQI of the SCG radio link is below a certain threshold.

For uplink SRB selection, the UE 506 signals uplink SRB data. Therefore, the UE 506 may need to determine which SRB can be used for delivery. The following example options may be used: (1) based on downlink SRB selection, (2) based on configuration, or (3) based on radio conditions.

For (1) downlink SRB-based selection, the same radio link can be used for the corresponding downlink SRB signal. The option can be used for response messages, such as RRC Connection Reconfiguration Complete.

For (2) configuration-based, the RAN signals to the UE 506 which SRB can be used to send a specific UL RRC message. For example, the measurement configuration indicates which SRB can be used for the corresponding MeasurementReport message. In aspect 506, the RAN signals to the UE which SRB should be used to send a specific UL RRC message.

For (3) based on radio conditions, the UE 506 selects MCG-SRB or SCG-SRB based on the radio conditions of each wireless link.

FIG13 is a diagram 1300 illustrating a call flow for secondary base station 504 (S-NB) connection establishment. FIG1300 illustrates an example call flow for secondary connection establishment and secondary base station 504 (S-NB) change procedures. In one embodiment, the RAB establishment procedure and the security mode command procedure may occur after step 1, however, the RAB establishment procedure and the security mode command procedure may be omitted from the call flow.

At step 0, the UE 506 performs a PLMN search and camps on a RAT cell associated with the master base station 502 (M-NB).

At step 1, UE 506 establishes an RRC connection with the master base station 502 (M-NB).

At step 2 (optional), for example, when the master base station 502 (M-NB) fails to obtain the UE capacity for the UE 506 from the core network entity (e.g., MME), the master base station 502 (M-NB) requests the UE 506 to report the UE capacity. The UE 506 reports the UE capacity of the RAT associated with the master base station 502 (M-NB) and the total measured capacity to the master base station 502 (M-NB).

In step 3, the master base station 502 (M-NB) configures the UE 506 with the measurement configuration for the S-NB-associated RAT (S-NB RAT). The UE 506 then begins measurements of the secondary base station 504 (S-NB) RAT accordingly. When certain reporting criteria are met, the UE 506 sends a measurement report message including the measurement results of the detected secondary base station 504 (S-NB) RAT cells.

At step 4, the master base station 502 (M-NB) decides to add a secondary connection with the secondary base station 504 (S-NB), which is associated with the reported cell, based on, for example, the measured results of the cell and the remaining capacity at the master base station 502 (M-NB) and/or the secondary base station 504 (S-NB).

At step 5, the master base station 502 (M-NB) requests the secondary base station 504 (S-NB) to allocate radio resources for the SRB and specific E-RAB separated by the secondary base station 504 (S-NB), indicating E-RAB characteristics (E-RAB parameters, TNL address information corresponding to the bearer type).

In addition, the M-NB indicates the UE capacity of the RAT associated with the secondary base station 504 (S-NB) in SCG-ConfigInfo, which is used as the basis for reconfiguration by the secondary base station 504 (S-NB). In addition, the master base station 502 (M-NB) indicates the security key SK ^* _NB used for security enhancement of the secondary base station 504 (S-NB) and the corresponding SCG count used for key derivation in SCG-ConfigInfo.

The master base station 502 (M-NB) can provide the latest measurement results for the SCG cell requested to be added. The secondary base station 504 (S-NB) can reject the request (reject the request at step 6a).

When the RRM entity in the secondary base station 504 (S-NB) is able to accept the resource request, it allocates corresponding radio resources and allocates corresponding transport network resources according to the bearer option.

FFS may be optional (the secondary base station 504 (S-NB) triggers random access to enable synchronization of the secondary base station 504 (S-NB) radio resource configuration).

The secondary base station 504 (S-NB) provides the master base station 502 (M-NB) with the new radio resources for the SCG in the SCG-Config. For SCG bearers, the secondary base station 504 (S-NB) provides the new radio resources for the SCG as well as NG3 DL TNL address information for the corresponding E-RAB and security algorithm, as well as XN/X2 DL TNL address information for the separate bearers.

In contrast to SCG bearer, for the split bearer option, the master base station 502 (M-NB) may decide to request such an amount of resources from the secondary base station 504 (S-NB) that the QoS for the corresponding E-RAB is guaranteed by the exact sum of the resources provided by the master base station 502 (M-NB) and the secondary base station 504 (S-NB) together (or even more). The NB decision may be reflected in step 5 through the E-RAB parameters signaled to the secondary base station 504 (S-NB), which may be different from the E-RAB parameters received on S1/NG2.

For a specific E-RAB, the master base station 502 (M-NB) may request to directly establish an SCG or separate bearer, that is, without first establishing an MCG bearer.

In case of MCG split bearer, transmission of user plane data may be performed after step 6a.

In case of SCG bearer or SCG-split bearer, data forwarding and SN state transfer may be performed after step 6a.

At step 6 , the master base station 502 (M-NB) sends an RRC connection reconfiguration message to the UE 506 , including a new radio resource configuration of the SCG according to the SCG-Config of the secondary base station 504 (S-NB).

The UE 506 applies the new configuration and replies with an RRC Connection Reconfiguration Complete message. In case the UE 506 cannot comply with the (partial) configuration included in the RRC Connection Reconfiguration message, it performs a Reconfiguration Failure procedure.

FFS may be optional (7c). UE 506 synchronizes to the PScell (S-NB) of secondary base station 504. The order in which UE 506 sends the RRC Connection Configuration Complete message to the SCG and performs the random access procedure is undefined. Successful completion of the RRC Connection Reconfiguration procedure does not require a successful RA procedure to the SCG (7d). Master base station 502 (M-NB) notifies secondary base station 504 (S-NB) that UE 506 has successfully completed the reconfiguration procedure.

At step 7, in the case of SCG bearer or SCG separated bearer, and depending on the bearer characteristics of the corresponding E-RAB, the master base station 502 (M-NB) can take measures to minimize the service interruption caused by activating dual connectivity (data forwarding, SN state transfer).

At step 8, for the SCG bearer, an update of the UP path for the EPC may be performed.

Figure 14 is a diagram showing options for changing the call flow of the secondary base station 504. At step 0, the UE 506 and the network establish dual connectivity with the master base station 502 (M-NB) and the secondary base station 1002 (S-NB1).

In step 1, secondary base station 1002 (S-NB1) reconfigures UE 506 with the measurement configuration of a secondary base station (S-NB), such as the RAT (S-NB RAT) associated with secondary base stations 1002 and 1004. Secondary base station 1002 (S-NB1) sends an RRC Connection Reconfiguration message to UE 506 via an MCG radio link or an SCG radio link. UE 506 responds with an RRC Connection Reconfiguration Complete message to secondary base station 1002 (S-NB1) via the MCG radio link or the SCG radio link. UE 506 also sends an RRC: Measurement Report (S-NB RAT cell measurement results) to secondary base station 1002 (S-NB1) via the MCG radio link or the SCG radio link (step 1b).

At step 2, the secondary base station 1002 (S-NB1) determines a change of the secondary base station (S-NB) based on, for example, cell measurement results and the remaining capacity at the secondary base station 1002 (S-NB1) and/or the secondary base station 1004 (S-NB2).

In step 3, the secondary base station 1002 (S-NB1) initiates the handover request of the secondary base station (S-NB) by requesting the target secondary base station 1004 (S-NB2) to allocate resources for the UE 506 (e.g., the secondary base station 1004 (S-NB2)). The secondary base station 1002 (S-NB1) includes the SCG configuration of the old secondary base station (S-NB1) and the UE 506 capacity information currently stored in the secondary base station (S-NB1) in the handover request message.

In step 4, when the allocation of resources to the target secondary base station 1004 (S-NB2) is successful, the secondary base station 1004 (S-NB2) requests the master base station 502 (M-NB) to change the secondary base station to the secondary base station 1004 (S-NB2).

The secondary base station 1004 (S-NB2) provides the secondary base station 1004 (S-NB2) TNL information (NG3 DL TNL address information for the SCG bearer used for each E-RAB, and XN/X2 DL TNL address information for the separate bearers). The primary base station 502 (M-NB) derives SK ^* _NB using the new SCG count value for the target secondary base station 504 (S-NB). The primary base station 502 (M-NB) transmits the derived SK ^* _NB and the corresponding SCG count through the S-NB Change Request Confirmation procedure (step 4a).

In the case of an MCG split bearer, transmission of user plane data may be performed after step 4. In the case of an SCG bearer or an SCG split bearer, data forwarding and SN state transfer may be performed after step 4, such as data forwarding at step 8a and SN state transfer at step 8.

At step 5, when resources for the target secondary base station 1004 (S-NB2) are successfully allocated and the master base station 502 (M-NB) confirms the change of the secondary base station 1004 (S-NB2) (e.g., at step 4a), the target secondary base station 1004 (S-NB2) confirms the handover request via a handover request confirmation message. When forwarding is required, the target secondary base station 1004 (S-NB2) provides the forwarding address to the source base station 1002 (S-NB1) (step 5).

The secondary base station 1002 (S-NB1) then initiates the release of resources to the UE 506 (eg, as part of step 6a).

Direct data forwarding or indirect data forwarding may be used for SCG bearers or SCG-split bearers, for example, at step 8a. Receiving the handover request confirm message (step 5) triggers the source secondary base station 1002 (S-NB1) to stop providing user data to the UE and, if appropriate, start data forwarding, for example, at step 8a.

At step 6, the secondary base station 1002 (S-NB1) sends an RRC connection reconfiguration message to the UE 506, for example, via the master base station 502 (M-NB). The UE 506 sends an RRC connection reconfiguration complete message back to the secondary base station 1004 (S-NB2), for example, via the master base station 502 (M-NB).

In the event that UE 506 cannot comply with a portion of the configuration included in the RRC connection reconfiguration message, UE 506 may perform a reconfiguration failure procedure. At step 6c, FFS may be optional. The UE synchronizes with the target S-NB, for example, at step 6a or step 6b.

The RRC Connection Reconfiguration message at step 6 is sent via an MCG radio link (i.e., an MCG link via an MCG SRB or a separate SRB) or an SCG radio link (i.e., an SCG link via an SCG SRB or a separate SRB). The RRC Connection Reconfiguration Complete message at step 6b may be sent via an MCG SRB radio link (i.e., an MCG link via an MCG SRB or a separate SRB) or an S-NB SCG SRB radio link (i.e., an SCG link via an SCG SRB or a separate SRB). Uplink SRB selection may be based on downlink SRB selection or NW configuration.

At step 7, when the RRC connection reconfiguration process is successful, the target secondary base station 1004 (S-NB2) notifies the master base station 502 (M-NB) that the S-NB change is successfully completed.

At step 8, data forwarding from the S-NB occurs when appropriate. Data forwarding may be initiated as early as when the source S-NB receives an S-NB release request message from the master base station 502 (M-NB).

At step 9, when one of the bearer environments is configured using the SCG bearer option at the source base station S-NB, a path update may be triggered by the master base station 502 (M-NB), which may trigger a bearer modification from the MME 1406 to the GW 1408 (e.g., step 9a), an end of the marked packet from the secondary base station 1002 (e.g., step 9b), and an E-RAB modification confirmation from the MME 1406 (e.g., step 9c).

At step 10, upon receiving the UE environment release message from the master base station 502 (M-NB), the source secondary base station 1002 (S-NB1) may release the radio and C-plane related resources associated with the UE environment. Ongoing data forwarding may continue.

15 is a diagram 1500 illustrating an example of reconfiguration of a secondary/supplementary base station 504 when the capacity of a UE 506 is updated. Schematic diagram 1500 includes a master base station 502, a secondary base station 504 (S-NB), and a UE 506.

At step 0, the UE 506 and the RAN establish connections with the master base station 502 (M-NB) and the secondary base station 504 (S-NB).

At step 1 , the master base station 502 (M-NB) determines the SCell addition and reconfigures the UE 506 with the new CA configuration.

At step 2, the UE 506 updates the UE capacity information of another RAT based on the resources (eg, available RF chains) of the remaining UEs.

At step 3, the UE 506 reports the updated UE capacity information (M-NB) to the secondary base station 504 (S-NB).

At step 4, it is determined that the secondary base station 504 (S-NB) is reconfigured. Therefore, the secondary base station 504 (S-NB) can reallocate resources to the UE based on the updated UE capacity information and determine to reconfigure the UE accordingly.

At step 5, the S-NB reconfigures the SCG link by sending an RRC connection reconfiguration message via the S-NB MCG SRB or the S-NB SCG SRB. The UE 506 performs the commanded reconfiguration and sends back a response message after the reconfiguration (e.g., at steps 5a and 5b).

FIG16 is a flow chart 1600 of a method of wireless communication. The method may be performed by a base station (e.g., base station 102, 180, 310, 402, 502, 504, 1002, 1004). The base station may be a secondary base station 1002, 1004 (S-NB, SNB1, S-NB2). At 1602, the base station establishes a radio link for dual connectivity to a UE. The radio link includes an SRB. For example, the base station 102, 180, 310, 402, 1002 establishes a radio link for dual connectivity to the UE (FIG. 10, step 0; FIG14, step 0). The radio link includes an SRB. In one aspect, the radio link includes a RAT.

At 1604, the base station sends an RRC connection reconfiguration signal to the UE to enable measurement reporting associated with the radio link. For example, base station 102, 180, 310, 402, 1002 sends an RRC connection reconfiguration signal to the UE to enable measurement reporting associated with the radio link ( FIG. 10 , step 1; FIG. 14 , step 1). In one aspect, the RRC connection reconfiguration is sent to the UE. In one aspect, the RRC connection reconfiguration is forwarded to the primary base station.

At 1606, the base station receives an RRC connection reconfiguration complete signal from the UE at the secondary base station. For example, the base station 102, 180, 310, 402, 1002 receives an RRC connection reconfiguration complete signal from the UE 506 at the secondary base station 102, 180, 310, 402, 1002 ( FIG. 10 , step 1a; FIG. 14 , step 1a).

At 1608, the base station receives a measurement report from the UE associated with the radio link at the secondary base station. For example, the base station 102, 180, 310, 402, 1002 receives a measurement report from the UE 506 associated with the radio link at the secondary base station 102, 180, 310, 402, 1002 ( FIG. 10 , step 1b; FIG. 14 , step 1b).

At 1610, the base station determines a base station change based on the measurement report at the secondary base station. For example, the base stations 102, 180, 310, 402, and 1002 determine a base station change based on the measurement report at the secondary base station 102, 180, 310, 402, and 1002 ( FIG. 10 , step 2; FIG. 14 , step 2).

At 1612, the base station sends a handover request in response to the determination. For example, the base station 102, 180, 310, 402, 1002 sends a handover request in response to the determination ( FIG. 10 , step 3; FIG. 14 , step 3).

At 1614, the base station receives the handover request confirmation. For example, base station 102, 180, 310, 402, 1002 receives the handover request confirmation (FIG. 10, step 5; FIG. 14, step 5).

At 1616, the base station sends an RRC connection reconfiguration based on the handover request confirmation. For example, the base station 102, 180, 310, 402, 1002 sends an RRC connection reconfiguration based on the handover request confirmation (Figure 10, step 6; Figure 14, step 6).

FIG17 is a flow chart 1700 of a method for wireless communication. The method may be performed by a UE (e.g., UE 104, 350, 404, 506). At 1702, the UE establishes a first wireless link with a primary base station. For example, UE 104, 350, 404, 506 establishes a first wireless link with a primary base station 102, 180, 310, 402, 502, 504 ( FIG10 , step 0; FIG14 , step 0).

At 1704, the UE establishes a second radio link with a first cell associated with the secondary base station. The second radio link includes an SRB. For example, UE 104, 350, 404, or 506 establishes a second radio link with a first cell associated with the secondary base station 102, 180, 310, 402, 502, or 504. The second radio link includes an SRB ( FIG. 10 , step 0; FIG. 14 , step 0).

At 1706, the UE receives an RRC connection reconfiguration signal from the second radio link SRB to enable measurement reporting associated with the second radio link. For example, the UE 104, 350, 404, 506 receives an RRC connection reconfiguration signal from the second radio link SRB (1002) to enable measurement reporting associated with the second radio link ( FIG. 10 , step 1; FIG. 14 , step 1).

In one aspect, the RRC connection reconfiguration is received from the secondary base station using a second radio link (SRB). In another aspect, the RRC connection reconfiguration is received from the primary base station using a first radio link (SRB). The RRC connection reconfiguration may be included in a transparent container. In another aspect, the RRC connection reconfiguration is received from the primary base station via the first radio link or via the second radio link. In another aspect, the RRC connection reconfiguration signal is received from the second radio link (SRB) to enable measurement reporting associated with the second radio link.

At 1708, the UE provides a measurement report to the secondary base station associated with the second radio link using the second radio link SRB. For example, the UE 104, 350, 404, 506 provides a measurement report to the secondary base station associated with the second radio link using the second radio link SRB ( FIG. 10 , step 1b; FIG. 14 , step 1b).

In an aspect, providing the measurement report from the UE to the secondary base station uses the second radio link SRB to provide the measurement report to the secondary base station associated with the second radio link.

At 1710, the UE receives an RRC connection reconfiguration indicating a base station change. For example, the UE 104, 350, 404, 506 receives an RRC connection reconfiguration indicating a base station change ( FIG. 10 , step 6; FIG. 14 , step 6).

FIG18 is a flow chart 1800 of a method for wireless communication. The method may be performed by a base station (e.g., base station 102, 180, 310, 402, 502, 504). The base station may be a secondary base station 1002, 1004 (S-NB, SNB1, S-NB2). At 1802, the base station, acting as a secondary base station for dual connectivity, establishes a radio link with a UE. The radio link may include an SRB. For example, base station 102, 180, 310, 402, 1002, acting as a secondary base station for dual connectivity, establishes a radio link with UE 506 ( FIG10 , step 0; FIG14 , step 0).

At 1804, the base station determines at least one of a cell change or an SN change at the secondary base station. For example, base stations 102, 180, 310, 402, and 1002 determine at least one of a cell change or an SN change at the secondary base station ( FIG. 10 , step 2; FIG. 14 , step 2).

At 1806, the base station sends a handover request in response to the determination. For example, the base station 102, 180, 310, 402, 1002 sends a handover request in response to the determination ( FIG. 10 , step 3; FIG. 14 , step 3).

At 1808, the base station receives the handover request confirmation. For example, the base station 102, 180, 310, 402, 1002 receives the handover request confirmation (FIG. 10, step 5; FIG. 14, step 5).

At 1810, the base station sends an RRC connection reconfiguration via an SRB based on the handover request confirmation. For example, base stations 102, 180, 310, 402, and 1002 send an RRC connection reconfiguration via an SRB based on the handover request confirmation ( FIG. 10 , step 6; FIG. 14 , step 6). In one aspect, the RRC connection reconfiguration can be sent from the secondary base station 1002 to the UE 506 ( FIG. 10 , step 6). In one aspect, the RRC connection reconfiguration can be sent from the secondary base station 1002 to the UE 506 via the master base station 502 (M-NB) ( FIG. 14 , step 6).

FIG19 is a flow chart 1900 of a method for wireless communication. The method may be performed by a UE (e.g., UE 104, 350, 404, 506). At 1902, the UE establishes a first wireless link with a primary base station. For example, UE 104, 350, 404, 506 establishes a first wireless link with a primary base station 102, 180, 310, 402, 502 ( FIG10 , step 0; FIG14 , step 0).

At 1904, the UE establishes a second radio link with a first cell associated with a secondary base station. The second radio link may include an SRB. For example, UE 104, 350, 404, or 506 establishes a second radio link with a first cell associated with a secondary base station 102, 180, 310, 402, 1002, or 1004 ( FIG. 10 , step 0; FIG. 14 , step 0).

At 1906, the UE receives an RRC connection reconfiguration signal from the second radio link SRB to establish a second radio link with the second cell. For example, UE 104, 350, 404, 506 receives an RRC connection reconfiguration signal from the second radio link SRB to establish a second radio link with the second cell ( FIG. 10 , step 1; FIG. 14 , step 1).

In one aspect, the RRC connection reconfiguration is sent to the primary base station 102, 180, 310, 402, 502, 504, and then the RRC connection reconfiguration is sent to the UE 104, 350, 404, 506 via one of the first radio link or the second radio link. In one aspect, the RRC connection reconfiguration is received from another secondary base station 102, 180, 310, 402, 502, 504. In one aspect, the RRC connection reconfiguration is received from the primary base station 502.

At 1908, the UE sends an RRC connection reconfiguration complete message to the secondary base station. For example, the UE 104, 350, 404, 506 sends an RRC connection reconfiguration complete message to the secondary base station 102, 180, 310, 402, 1004 ( FIG. 10 , step 6b; FIG. 14 , step 6b).

At 1910, the UE performs a random access procedure. For example, the UE 104, 350, 404, 506 performs a random access procedure (FIG. 10, step 6c; FIG. 14, step 6c).

FIG20 is a flow chart 2000 of a method for wireless communication. The method may be performed by a base station (e.g., base station 102, 180, 310, 402, 502, or 504). The base station may be a secondary base station 1004. At 2002, the base station sends a handover request confirmation. For example, base station 102, 180, 310, 402, or 1004 sends a handover request confirmation ( FIG10 , step 5; FIG14 , step 5).

At 2004, the base station receives the RRC reconfiguration complete. For example, base stations 102, 180, 310, 402, 1004 receive the RRC reconfiguration complete (FIG. 10, step 6b; FIG. 14, step 6b).

At 2006, the base station sends a message indicating that the secondary base station change is complete. For example, base stations 102, 180, 310, 402, 502, and 504 send a message indicating that the secondary base station change is complete (FIG. 10, step 7; FIG. 14, step 7).

At 2008, the base station performs a random access procedure. For example, base stations 102, 180, 310, 402, 502, 504 perform a random access procedure (FIG. 10, step 6c; FIG. 14, step 6c).

Figure 21 is a conceptual data flow diagram 2100 illustrating the data flow between different units/components in an exemplary device 506'. The device can be a UE. The device includes: a receiving component 2104 that receives an RRC connection reconfiguration signal from a second radio link SRB to establish a second radio link with a second cell and/or receives an RRC connection reconfiguration for indicating a base station change (2152); a radio link establishing component 2106 that establishes a first radio link with a primary base station and/or establishes a second radio link with a first cell (e.g., by controlling the receiving component 2104 and/or the sending component 2110 using control signals 2154, 2156), the first cell being associated with the secondary base station; a measurement reporting component 2108 that provides a measurement report (2158) to the secondary base station associated with the second radio link using the second radio link SRB (e.g., based on a signal 2160 from the receiving component 2104); a sending component 2110, which sends the RRC connection reconfiguration completion to the secondary base station and/or sends the measurement report (2162) from the measurement reporting component 2108; and a random access process component 2112, which performs the random access process (for example, by using control signals 2164, 2166 to control the receiving component 2104 and/or the sending component 2110).

The apparatus may include additional components that execute each of the blocks in the algorithms in the aforementioned flowcharts of Figures 17 and 19. Thus, each of the blocks in the aforementioned flowcharts of Figures 17 and 19 may be executed by a component, and the apparatus may include one or more of these components. These components may be one or more hardware components that are specifically configured to: execute the described process/algorithm, be implemented by a processor configured to execute the described process/algorithm, be stored in a computer-readable medium for implementation by a processor, or some combination thereof.

FIG22 is a diagram 2200 illustrating an example of a hardware implementation for an apparatus 2102′ employing a processing system 2214. The processing system 2214 can be implemented using a bus architecture, generally represented by a bus 2224. The bus 2224 can include any number of interconnecting buses and bridges, depending on the specific application of the processing system 2214 and the overall design constraints. The bus 2224 links together various circuits, including one or more processors and/or hardware components represented by the processor 2204, components 2104, 2106, 2108, 2110, 2112, and computer-readable medium/memory 2206. The bus 2224 can also link various other circuits, such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and are not described further.

Processing system 2214 may be coupled to transceiver 2210. Transceiver 2210 is coupled to one or more antennas 2220. Transceiver 2210 provides a means for communicating with various other devices via a transmission medium. Transceiver 2210 receives signals from one or more antennas 2220, extracts information from the received signals, and provides the extracted information to processing system 2214, specifically receiving component 2104. Receiving component 2104 receives an RRC connection reconfiguration signal from a second radio link (SRB) to establish a second radio link with a second cell and/or receives an RRC connection reconfiguration signal indicating a base station change. Furthermore, transceiver 2210 receives information from processing system 2214, specifically from transmitting component 2110, which transmits an RRC connection reconfiguration complete to a secondary base station and/or transmits a measurement report from measurement reporting component 2108. Based on the received information, transceiver 2210 generates a signal to be applied to one or more antennas 2220. Processing system 2214 includes processor 2204 coupled to computer-readable medium/memory 2206. Processor 2204 is responsible for general processing, including executing software stored on computer-readable medium/memory 2206. When executed by processor 2204, this software causes processing system 2214 to perform the various functions described above for any particular device. Computer-readable medium/memory 2206 may also be used to store data manipulated by processor 2204 when executing the software. Processing system 2214 also includes at least one of components 2014, 2106, 2108, 2110, and 2112. These components may be software components running on processor 2204, software components residing/stored in computer-readable medium/memory 2206, one or more hardware components coupled to processor 2204, or some combination thereof. Processing system 2214 may be a component of UE 350 and may include memory 360 and/or at least one of TX processor 368, RX processor 356, and controller/processor 359.

In one configuration, an apparatus 2102/2102′ for wireless communication includes: means for establishing a first radio link with a primary base station, means for establishing a second radio link with a first cell, the first cell being associated with a secondary base station, wherein the second radio link includes an SRB, means for receiving an RRC connection reconfiguration signal from the second radio link SRB to enable measurement reporting associated with the second radio link, means for providing a measurement report to the secondary base station associated with the second radio link using the second radio link SRB, means for receiving an RRC connection reconfiguration indicating a base station change, means for sending an RRC connection reconfiguration completion to the secondary base station, and means for performing a random access procedure.

The aforementioned means may be one or more of the aforementioned components of the device 2102 and/or the processing system 2214 of the device 2102' configured to perform the functions recited by the aforementioned means. As described above, the processing system 2214 may include the TX processor 368, the RX processor 356, and the controller/processor 359. Thus, in one configuration, the aforementioned means may be the TX processor 368, the RX processor 356, and the controller/processor 359 configured to perform the functions recited by the aforementioned means.

Figure 23 is a conceptual data flow diagram 2300 illustrating the flow of data between different units/components in an exemplary device 2302'. The device may be a base station. The apparatus includes: a receiving component 2304 for receiving, at a secondary base station, an RRC connection reconfiguration complete signal from a UE; receiving, at the secondary base station, a measurement report from the UE associated with a radio link; receiving a handover request confirmation; and receiving an RRC reconfiguration complete signal; a radio link establishing component 2306 for establishing a radio link for dual connectivity to the UE, wherein the radio link includes an SRB, and/or establishing a radio link with the UE as a secondary base station for dual connectivity, wherein the radio link includes an SRB; a determining change component 2308 for determining, at the secondary base station based on the measurement report, a base station change, and determining, at the secondary base station, at least one of a cell change or an SN change; a sending component 2310 for sending an RRC connection reconfiguration signal to the UE to enable measurement reporting associated with the radio link, sending a handover request in response to the determination, sending an RRC connection reconfiguration based on the handover request confirmation, sending an RRC connection reconfiguration based on the handover request confirmation via the SRB, sending a handover request confirmation, and sending a secondary base station change complete signal; and a random access procedure component 2312 for performing a random access procedure.

The apparatus may include additional components that execute each of the blocks in the algorithms in the aforementioned flowcharts of Figures 16, 18, and 20. Thus, each block in the aforementioned flowcharts of Figures 16, 18, and 20 may be executed by a component, and the apparatus may include one or more of these components. These components may be one or more hardware components that are specifically configured to: execute the process/algorithm, be implemented by a processor configured to execute the process/algorithm, be stored in a computer-readable medium for implementation by a processor, or some combination thereof.

FIG24 is a diagram 2400 illustrating an example of a hardware implementation for an apparatus 2302′ employing a processing system 2414. The processing system 2414 can be implemented using a bus architecture, generally represented by a bus 2424. The bus 2424 can include any number of interconnecting buses and bridges, depending on the specific application of the processing system 2414 and the overall design constraints. The bus 2424 links together various circuits, including one or more processors and/or hardware components represented by the processor 2404, components 2304, 2306, 2308, 2310, 2312, and computer-readable medium/memory 2406. The bus 2424 can also link various other circuits, such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore not described further.

The processing system 2414 may be coupled to the transceiver 2410. The transceiver 2410 is coupled to one or more antennas 2420. The transceiver 2410 provides a means for communicating with various other devices via a transmission medium. The transceiver 2410 receives signals from the one or more antennas 2420, extracts information from the received signals, and provides the extracted information to the processing system 2414. Specifically, the receiving component 2304 receives an RRC connection reconfiguration complete signal from the UE at the secondary base station, receives a measurement report from the UE associated with the radio link at the secondary base station, receives a handover request acknowledgment, and receives an RRC reconfiguration complete. Furthermore, transceiver 2410 receives information from processing system 2414. Specifically, transmitting component 2310 transmits an RRC connection reconfiguration signal to the UE to enable measurement reporting associated with the radio link, transmits a handover request in response to the determination, transmits an RRC connection reconfiguration based on a handover request acknowledgment, transmits an RRC connection reconfiguration based on the handover request acknowledgment via an SRB, transmits a handover request acknowledgment, transmits a secondary base station change completion, and generates a signal to be applied to one or more antennas 2420 based on the received information. Processing system 2414 includes a processor 2404 coupled to a computer-readable medium/memory 2406. Processor 2404 is responsible for general processing, including executing software stored on computer-readable medium/memory 2406. When executed by processor 2404, the software causes processing system 2414 to perform the various functions described above for any particular apparatus. Computer-readable medium/memory 2406 may also be used to store data that is manipulated by processor 2404 when executing the software. The processing system 2414 also includes at least one of the components 2304, 2306, 2308, 2310, and 2312. The components may be software components running on the processor 2404, software components residing/stored in the computer-readable medium/memory 2406, one or more hardware components coupled to the processor 2404, or some combination thereof. The processing system 2414 may be a component of the base station 310 and may include the memory 376 and/or at least one processor of the TX processor 316, the RX processor 370, and the controller/processor 375.

In one configuration, an apparatus 2302/2302′ for wireless communication includes: means for establishing a radio link for dual connectivity to a UE, wherein the radio link includes an SRB, means for sending an RRC connection reconfiguration signal to the UE to enable measurement reporting associated with the radio link, means for receiving an RRC connection reconfiguration complete signal from the UE at a secondary base station, means for receiving a measurement report from the UE associated with the radio link at the secondary base station, means for determining a base station change at the secondary base station based on the measurement report, means for sending a handover request in response to the determination, means for receiving a handover request confirmation, and means for sending a handover request confirmation based on the handover request confirmation. Means for RRC connection reconfiguration, means for establishing a radio link with a UE as a secondary base station for dual connectivity, wherein the radio link includes an SRB, means for determining at least one of a cell change or a SN change at the secondary base station, means for sending a handover request in response to the determination, means for receiving a handover request confirmation, means for sending an RRC connection reconfiguration based on the handover request confirmation via the SRB, means for sending a handover request confirmation, means for receiving an RRC reconfiguration complete, and means for sending a secondary base station change complete. The aforementioned means may be one or more of the aforementioned components of apparatus 2302 and/or the processing system 2414 of apparatus 2302' configured to perform the functions described by the aforementioned means. As described above, the processing system 2414 may include the TX processor 316, the RX processor 370, and the controller/processor 375. Thus, in one configuration, the aforementioned means may be the TX processor 370, the RX processor 356, and the controller/processor 375 configured to perform the functions described by the aforementioned means.

Some aspects may be related to capacity coordination across RATs. The RAN can address all use cases, requirements, and deployment scenarios. Aggregation scenarios may include requirements such as: (1) the RAN architecture can support tight interworking between the new RAT and LTE and/or (2) high-performance inter-RAT mobility and aggregation of data flows via at least dual connectivity between LTE and the new RAT. Both collocated and non-collocated site deployments can support aggregation scenarios.

Aspects may include the following cell layout scenarios, where Node B locations for LTE-NR aggregation can be captured in the TR. LTE and NR "cells" can overlap and be co-located, providing nearly identical coverage; both can be macro or small cells. LTE and NR cells can overlap and be co-located, or not co-located, providing different coverage; one can be a macro cell and the other a small cell.

In aspects, the following scenarios in terms of CN connectivity for LTE-NR aggregation can be captured in TR. NR can be tightly integrated in LTE via EPC (U-plane data is split at CN or RAN). LTE can be tightly integrated in NR via a new CN (U-plane data is split at CN or RAN). NR can be tightly integrated in LTE via a new CN (U-plane data is split at CN or RAN). In aspects, in terms of cell layout for standalone NR, the following scenarios are captured in TR, including (1) macro cell deployment only, (2) heterogeneous deployment, and/or (3) small cell deployment only.

On the other hand, in terms of CN connectivity for single RAT and inter-RAT independent operation, the following scenarios can be captured in the TR. For single RAT operation, (1) the NR NodeB connects to the new CN, and (2) the LTE eNB connects to the NR NodeB's new CN (or EPC as it is today). For inter-RAT mobility; (1) the LTE eNB connects to the EPC and the NR NodeB connects to the new CN, and/or (2) both the LTE eNB and the NR NodeB connect to the new CN.

Aspects include NR scenarios with 4G/Wi-Fi, regarding UE capacity and the resulting correlation between RRC ASN.1 and procedures. In UMTS and LTE network deployments, there has been a recurring issue with UE capacity sizing. In 3G, the capacity was transmitted with each RRC connection. This approach indirectly provided some flexibility to the UE in terms of being able to change its capacity over time; however, it consumed system resources. This approach initially worked well when the capacity was small. Then, the UMTS capacity began to carry the LTE capacity, including all carrier combinations. That's when call setup began to fail, especially in poor radio conditions, because transmitting the capacity took so long that the network would time out and release the RRC connection [add reference to QC document].

For 4G, 3GPP decided not to send capacity on every RRC connection for a number of reasons. Instead, the network saved UE capacity and moved it as the UE moved, avoiding duplicate transmissions over the air. Saving UE capacity and moving it as the UE moved should be equally effective when the UE moves from UMTS to LTE. However, there are two potential problems with saving UE capacity and moving it as the UE moved. First, by design, the process eliminates the ability of the UE to adjust UE capacity over time. Second, as the number of band combinations increases, the system may be subject to different size limitations. 3GPP addressed the limited number of band combinations in ASN.1 that can be reported by: (1) allowing the network to provide a list of bands used in the network and allowing the network to advertise the maximum number of carriers combined in the network, (2) allowing the UE to skip intermediate band combinations, and (3) adding new band combination containers.

NR may present the following issues regarding UE capacity: the number of supported combinations and inter-RAT communications has increased. With increasing air interface integration, future UEs will support more LTE band combinations, followed by NR+4G band combinations and NR+Wi-Fi band combinations. Furthermore, with features such as MIMO, NAICS, dual connectivity, uplink carrier aggregation, and the number of CSI processes, the number of combinations continues to grow. Combining different air interface carrier combinations will also result in more combinations, and the amount of capacity a UE needs to transmit will continue to increase in a combinational manner.

With inter-RAT communication, the UE may need to update the UE's capabilities. Although the LTE standard allows the UE to update the UE's capabilities in the event of a change in GERAN or UMTS, the standard also prohibits the UE from making any changes to the UE's LTE capabilities.

Managing UE capacity can be an issue in both LTE, NR, and potentially Wi-Fi. Not all combinations are useful. For example, Wi-Fi may be out of coverage, and coordination with Wi-Fi may be impossible/unlikely, especially in large legacy deployments, or with limited network capacity or load constraints.

In some aspects, NR with 4G/Wi-Fi may be limited. Offloaded traffic may require the full capacity of the required system, whether small cells or Wi-Fi. (Avoiding reserving resources for each RAT). Multiple slices may be more active at different times.

Some aspects may have the following options for UE capacity coordination: First, the UE reports all RAT capacities to one RAT, and the NW coordinates the configuration between the RATs, not exceeding the UE capacity. The NB can have a (semi-)static partitioning between the RATs, or dynamically coordinate the configuration for the UE cap. Observation: As discussed in 3, this is not scalable. For the foreseeable future, updates to LTE and NR will be combined. Second, the UE can report the capacity of each RAT (LTE and NR independent UE capacity).

The UE can semi-statically split the UE cap, or dynamically update the UE cap for each RAT, for example when another link is modified. In some cases, the network may not be aware of the situation. (Local screen mirroring over Wi-Fi.)

In one aspect, the UE may report the capacity of each RAT. In another aspect, the UE may not report the UE's NR capacity to the LTE network, nor may it send the UE's LTE capacity to the NR network. In another aspect, NR may employ dynamic capacity negotiation.

It should be understood that the specific order or hierarchy of blocks in the disclosed process/flowcharts is illustrative of exemplary methods. Based on design preferences, it is understood that the specific order or hierarchy of blocks in the process/flowcharts may be rearranged. In addition, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order and are not intended to be limited to the specific order or hierarchy presented.

The foregoing description is provided to enable those skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein, but rather to conform to the full scope consistent with the claim language, wherein reference to an element in the singular form is not intended to mean "one and only one," but rather "one or more," unless otherwise specified. The word "exemplary" as used herein refers to "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" is not necessarily to be interpreted as being more preferred or more advantageous than other aspects. Unless otherwise specified, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" can be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combination can include one or more members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to one of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is expressly recited in the claims. The words "module," "mechanism," "element," "device," etc. are not substitutes for the word "unit." Thus, any claim element should not be construed as unit-plus-function unless the element is expressly recited using the phrase "unit for..."

Claims (38)

1. A method performed by a secondary base station, comprising: A radio link for dual connectivity to a user equipment (UE) is established on the primary cell group (MCG), wherein the radio link includes a signaling radio bearer (SRB). The auxiliary base station sends a Radio Resource Control (RRC) connection reconfiguration signal to the UE to enable measurement reporting associated with the radio link and subsequent NR RRC messages on the new radio NR Uu; The secondary base station receives an RRC connection reconfiguration complete signal from the UE; and The secondary base station receives a measurement report from the UE associated with the radio link. 2. The method according to claim 1, further comprising: determining a secondary base station change based on the measurement report at the secondary base station. 3. The method according to claim 2, further comprising: In response to the determination, a handover request is sent; Receive handover request confirmation; and Based on the switching request confirmation, an RRC connection reconfiguration is sent. 4. The method of claim 3, wherein the RRC connection reconfiguration is sent to the UE. 5. The method according to claim 3, wherein the RRC connection reconfiguration is forwarded to the primary base station. 6. The method of claim 1, wherein the wireless link comprises a RAT. 7. A method performed by a user equipment (UE), comprising: Establish the first wireless link with the main base station; A second radio link is established on the primary cell group (MCG) radio link. The second radio link is associated with the secondary base station of the primary cell. The second radio link includes the signaling radio bearer (SRB). Receive a Radio Resource Control (RRC) connection reconfiguration signal from the secondary base station on the second radio link SRB to enable measurement reporting associated with the second radio link and subsequent NR RRC messages on the new radio NR Uu; Send an RRC connection reconfiguration complete signal to the secondary base station; and The second wireless link SRB is used to provide measurement reports to the secondary base station associated with the second wireless link. 8. The method of claim 7, further comprising: receiving an RRC connection reconfiguration for indicating a change in the secondary base station. 9. The method of claim 8, wherein the RRC connection reconfiguration is received from the secondary base station using the second radio link SRB. 10. The method of claim 8, wherein the RRC connection reconfiguration is received from the primary base station, and wherein the RRC connection reconfiguration is included in a transparent container. 11. The method of claim 10, wherein the RRC connection reconfiguration is received from the master base station via the first radio link or via the second radio link. 12. The method of claim 7, wherein the first wireless link comprises an SRB. 13. An apparatus for a secondary base station, the apparatus comprising: A unit for establishing a radio link for dual connectivity to a user equipment (UE) on a primary cell group (MCG), wherein the radio link includes a signaling radio bearer (SRB). A unit for sending a Radio Resource Control (RRC) connection reconfiguration signal from the secondary base station to the UE to enable measurement reports associated with the radio link and subsequent NR RRC messages on the new radio NR Uu; A unit for receiving an RRC connection reconfiguration completion signal from the UE at the secondary base station; and A unit for receiving measurement reports from the UE associated with the radio link at the secondary base station. 14. The apparatus of claim 13, further comprising: a unit for determining a change in the secondary base station based on the measurement report at the secondary base station. 15. The apparatus of claim 14, further comprising: A unit for sending a switching request in response to the determination; A unit for receiving handover request confirmations; and A unit for sending RRC connection reconfiguration based on the handover request confirmation. 16. The apparatus of claim 15, wherein the RRC connection reconfiguration is sent to the UE. 17. The apparatus of claim 15, wherein the RRC connection reconfiguration is forwarded to the primary base station. 18. The apparatus of claim 13, wherein the wireless link comprises a RAT. 19. An apparatus for a user equipment (UE), the apparatus comprising: A unit used to establish the first wireless link with the main base station; A unit for establishing a second radio link on the primary cell group (MCG) radio link, wherein the second radio link is associated with a secondary base station and the first cell, and wherein the second radio link includes a signaling radio bearer (SRB). A unit for receiving a radio resource control (RRC) connection reconfiguration signal from the secondary base station on the second radio link (SRB) to enable measurement reports associated with the second radio link and subsequent NR RRC messages on the new radio (NR Uu). A unit for sending an RRC connection reconfiguration completion signal to the secondary base station; and A unit for providing a measurement report to the secondary base station associated with the second wireless link using the second wireless link SRB. 20. The apparatus of claim 19, further comprising: a unit for receiving an RRC connection reconfiguration for instructing a change in the secondary base station. 21. The apparatus of claim 20, wherein the RRC connection reconfiguration is received from the secondary base station using the second radio link SRB. 22. The apparatus of claim 20, wherein the RRC connection reconfiguration is received from the primary base station, and wherein the RRC connection reconfiguration is included in a transparent container. 23. The apparatus of claim 22, wherein the RRC connection reconfiguration is received from the primary base station via the first wireless link or via the second wireless link. 24. The apparatus of claim 19, wherein the first wireless link comprises an SRB. 25. An apparatus for a secondary base station, the apparatus comprising: A processing system configured as follows: A radio link for dual connectivity to a user equipment (UE) is established on the primary cell group (MCG), wherein the radio link includes a signaling radio bearer (SRB). Send a Radio Resource Control (RRC) connection reconfiguration signal to the UE to enable measurement reporting associated with the radio link; The auxiliary base station sends a Radio Resource Control (RRC) connection reconfiguration signal to the UE to enable measurement reporting associated with the radio link and subsequent NR RRC messages on the new radio NR Uu; The secondary base station receives an RRC connection reconfiguration complete signal from the UE; and The secondary base station receives a measurement report from the UE associated with the radio link. 26. The apparatus of claim 25, wherein the processing system is further configured to: determine a secondary base station change at the secondary base station based on the measurement report. 27. The apparatus of claim 26, wherein the processing system is further configured to: In response to the determination, a handover request is sent; Receive handover request confirmation; and Based on the switch request confirmation, an RRC connection reconfiguration is sent. 28. The apparatus of claim 27, wherein the RRC connection reconfiguration is sent to the UE. 29. The apparatus of claim 27, wherein the RRC connection reconfiguration is forwarded to the primary base station. 30. The apparatus of claim 25, wherein the wireless link comprises a RAT. 31. An apparatus for a user equipment (UE), the apparatus comprising: The processing system is configured as follows: Establish the first wireless link with the main base station; A second radio link is established on the primary cell group (MCG) radio link. The second radio link is associated with the secondary base station of the primary cell. The second radio link includes the signaling radio bearer (SRB). Receive a Radio Resource Control (RRC) connection reconfiguration signal from the secondary base station on the second radio link SRB to enable measurement reporting associated with the second radio link and subsequent NR RRC messages on the new radio NR Uu; Send an RRC connection reconfiguration complete signal to the secondary base station; and The second wireless link SRB is used to provide measurement reports to the secondary base station associated with the second wireless link. 32. The apparatus of claim 31, wherein the processing system is further configured to receive an RRC connection reconfiguration for indicating a change in the secondary base station. 33. The apparatus of claim 32, wherein the RRC connection reconfiguration is received from the secondary base station using the second radio link SRB. 34. The apparatus of claim 32, wherein the RRC connection reconfiguration is received from the primary base station, and wherein the RRC connection reconfiguration is included in a transparent container. 35. The apparatus of claim 34, wherein the RRC connection reconfiguration is received from the primary base station via the first wireless link or via the second wireless link. 36. The apparatus of claim 31, wherein the first wireless link comprises an SRB. 37. A non-transitory computer-readable medium storing computer-executable code for wireless communication by a secondary base station, comprising code for performing the following operations: A radio link for dual connectivity to a user equipment (UE) is established on the primary cell group (MCG), wherein the radio link includes a signaling radio bearer (SRB). The auxiliary base station sends a Radio Resource Control (RRC) connection reconfiguration signal to the UE to enable measurement reporting associated with the radio link and subsequent NR RRC messages on the new radio NR Uu; Receives an RRC connection reconfiguration complete signal from the UE; and The measurement report is received from the UE associated with the wireless link. 38. A non-transitory computer-readable medium storing computer-executable code, comprising code for performing the following operations: Establish the first wireless link with the main base station; A second radio link is established on the primary cell group (MCG) radio link. The second radio link is associated with the secondary base station of the primary cell. The second radio link includes the signaling radio bearer (SRB). Receive a Radio Resource Control (RRC) connection reconfiguration signal from the secondary base station on the second radio link SRB to enable measurement reporting associated with the second radio link and subsequent NR RRC messages on the new radio NR Uu; Send an RRC connection reconfiguration complete signal to the secondary base station; and The second wireless link SRB is used to provide measurement reports to the secondary base station associated with the second wireless link.