WO2021072727A1

WO2021072727A1 - Switching from non-standalone mode to standalone mode for new radio communications

Info

Publication number: WO2021072727A1
Application number: PCT/CN2019/111822
Authority: WO
Inventors: Bing LENG; Shuang Wang; Jianfu ZHANG
Original assignee: Qualcomm Incorporated
Priority date: 2019-10-18
Filing date: 2019-10-18
Publication date: 2021-04-22

Abstract

Systems, apparatuses, and methods for switching from non-standalone mode (NSA) to standalone mode (SA) for New Radio (NR) communications. A user equipment (UE) may connect to an Long-Term Evolution (LTE) cell and an NR cell in NSA mode, wherein the LTE cell is an anchor cell for the NR cell. The UE may switch to SA mode for the NR cell under certain configurations or conditions, for example, by probing whether the NR cell may likely support SA mode based on decoding a system information block transmitted by the NR cell.

Description

SWITCHING FROM NON-STANDALONE MODE TO STANDALONE MODE FOR NEW RADIO COMMUNICATIONS

BACKGROUND

This disclosure relates generally to wireless communication, and more specifically, to techniques for switching from non-standalone mode (NSA) to standalone mode (SA) for New Radio communications.

Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power) . Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems (e.g., Long-Term Evolution (LTE) or New Radio (NR) ) . A wireless multiple-access communication system may include a number of base stations or access network nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE) .

SUMMARY

Systems, apparatuses, and methods are provided for switching from non-standalone mode to standalone mode for New Radio communications. A user equipment may connect to an LTE cell and an NR cell in NSA mode, wherein the LTE cell is an anchor cell for the NR cell. The UE may switch to SA mode for the NR cell under certain configurations or conditions, for example, by probing whether the NR cell may likely support SA mode based on decoding a system information block transmitted by the NR cell.

From an aspect, a method of wireless communication is provided. The method may be performed by a UE or component (s) thereof. The UE may connect to a Long-Term Evolution cell and may also connect to a New Radio cell in a non-standalone mode, wherein the LTE cell is an anchor cell for the NR cell. The UE may also determine whether to switch to a standalone mode for the NR cell, and if the SA mode is determined, connect to the NR cell in the SA mode.

From another aspect, a user equipment is provided. The user equipment may include a memory, and one or more processors coupled to the memory. The one or more processors may be configured to connect to a Long-Term Evolution cell and connect to a New Radio cell in a non-standalone mode, wherein the LTE cell is an anchor cell for the NR cell. Furthermore, the one or more processors may be further configured to determine whether to switch to a standalone mode for the NR cell. If the SA mode is determined, the one or more processors may be configured to connect to the NR cell in the SA mode.

From another aspect, an apparatus of wireless communications is provided. The apparatus may include means for connecting to connecting to a Long-Term Evolution cell. The apparatus may also include means for means for connecting to a New Radio cell in a non-standalone mode, wherein the LTE cell is an anchor cell for the NR cell. The apparatus may include means for determining whether to switch to a standalone mode for the NR cell. Furthermore, the apparatus may include means for connecting to the NR cell in the SA mode if the SA mode is determined.

From another aspect, a non-transitory computer-readable medium having instructions stored thereon is provided. The instructions may include codes executable for a user equipment to perform connecting to a Long-Term Evolution cell. The instructions may also include codes for connecting to a New Radio cell in a non-standalone mode, wherein the LTE cell is an anchor cell for the NR cell. Furthermore, the instructions may include codes for determining whether to switch to a standalone mode for the NR cell. Moreover, the instructions may also include codes for connecting to the NR cell in the SA mode if the SA mode is determined.

Various features and advantages of this disclosure are described in further details below. Other features will be apparent from the description, drawings, and/or the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative and non-limiting drawings are provided to aid in the description of various aspects and implementations. Unless specified otherwise, like reference symbols indicate like elements.

FIG. 1 illustrates an example of a wireless communication system in accordance with the present disclosure.

FIG. 2 illustrates an example of system architecture for non-standalone and standalone NR communications.

FIG. 3 illustrates an example of a flowchart of switching from NSA node to SA mode in accordance with the present disclosure.

FIG. 4 illustrates an example of a call flow for switching from NSA mode to SA mode in accordance with the present disclosure

FIG. 5 illustrates an example of a method of wireless communication in accordance with the present disclosure.

FIG. 6 illustrates an example of an apparatus of wireless communication in accordance with the present disclosure.

FIG. 7 illustrates a device in accordance with the present disclosure.

DETAILED DESCRIPTION

The fifth-generation (5G) New Radio wireless communication standards support two network deployment modes: non-standalone mode and standalone mode. The NSA mode uses a fourth-generation (4G) LTE cell as anchor cell and the LTE core network for network services. The NSA mode may speedup 5G commercialization because an LTE operator may retain the existing LTE core network and only upgrade base stations. On the other hand, the SA mode uses 5G core network which may provide latest features and advances (e.g., network slicing and network function virtualization) over the previous generations of core network. To save cost, operators may migrate their network from LTE to NR in difference phases, for example, upgrading cells to dual-mode cells (supporting both NSA mode and SA mode) and gradually retiring LTE core networks. Moreover, from user sides, NSA/SA dual mode handset may see increasing market demand.

During the network transition, an operator may place a UE by default on NSA mode, or the UE may fall back to NSA mode due to mobility or roaming. Nevertheless, a user may desire SA mode, for example, to utilize the newer network services by the NR core network. A UE may wait for the network or operator to redirect it to SA mode, which may or may not occur or be supported. To enhance user experience, a UE may proactively or opportunistically determine whether the NR cell (currently connected to in NSA mode) may actually be a dual-mode cell also supporting SA mode. For instance, the UE may attempt to decode a system information block transmitted over the air by the NR cell, and based on the decoded system information block, the UE may determine whether to switch to the SA mode.

Aspects of the disclosure introduced above are described below in the context of a wireless communication system. Illustrative and non-limiting examples of designs and techniques supporting switching from NSA mode to SA mode are then described. Aspects of the disclosure are illustrated by and described with reference to various apparatus diagrams, system diagrams, and flowcharts.

FIG. 1 illustrates an example of a wireless communication system 100 in accordance with the present disclosure. The wireless communication system 100 generally include user devices (e.g., UEs 110) and network devices (e.g., base stations 120 and entities of a core network 130) . Examples of the wireless communication system 100 may include various wireless network technologies, such as LTE or NR, as developed and standardized by the Third Generation Partnership Project (3GPP) .

A user equipment generally refers to a device (e.g., of an end-user) that utilizes wireless communication service provided by a wireless communication network. As illustrated, a UE 110 may take a variety of forms, such as a cellphone, a computation device, a machine-type-communication (MTC) or Internet-of-Things (IoT) device, or a vehicular device, and so on. UEs 110 may be dispersed throughout the wireless communication system 100, and each UE 110 may be stationary or mobile. As used herein, a “user equipment” may also be referred to as a subscriber station, an access terminal, a remote terminal, a handset, a user device, or generally a wireless communication device or some other suitable terminology in the context.

A base station generally refers to a network device that communicates wirelessly (e.g., via over-the-air radio channel) with user devices. Base stations 120 may communicate with one another and/or with the core network 130, e.g., through backhaul links or other network nodes. Base stations 120 often serve as entry points for a user equipment to access communication services provided by a wireless communication network. Base stations 120 (and in some examples, with other entities) may constitute a radio access network (RAN) , which connects UEs 110 to the core network 130 via certain radio access technology (RAT) , such as LTE or NR. In 3GPP context, a base station may be known as an evolved Node B (eNB) for LTE or a next generation Node B (gNB) for NR. But generally, as used herein, a “base station” may also be referred to as a base transceiver station, a radio base station, an access point, or some other suitable terminology in the context.

In general, a base station 120 may communicate with a UE 110 using communication resources in time, frequency, and/or space. Communication may occur in two directions: “downlink” (or “forward link” ) from the base station 120 to the UE 110; or in reverse, “uplink” (or “reverse link” ) from the UE 110 to the base station 120. Downlink and uplink transmissions may take place on same or different frequency bands and during same or different time instances. In terms of time resources, time intervals of transmission may be organized according to a “frame” structure. A frame may further be divided into a number of subframes or slots, each further containing a number of symbols, and so on. In terms of frequency resources, a variety of frequency bands (e.g., ranging from ultra-high frequency to extremely-high frequency) may be used. The frequency bands may be “licensed” (e.g., to an operator exclusively) , or “unlicensed” (or “shared” ) (e.g., shared by general users subject to interference and coexistence regulation) . On a frequency band, a “carrier” may generally refer to a set of radio frequency spectrum resources supporting uplink and/or downlink communication, such as transmission of physical signals or channels. In some examples a carrier may be made up of multiple sub-carriers (e.g., waveform signals of multiple different frequencies) . In terms of spatial resources, base stations 120 and/or UEs 110 may communicate on one or more (physical or virtual) antenna ports, for example, based on various single-user or multi-user, Multiple-Input and Multiple Output (MIMO) techniques, such as spatial diversity, multiplexing, or beamforming, and so on. Multiple antennas may be co-located or distributed in diverse geographic locations.

A base station 120 may operate one or more “cells” 122. The term “cell” generally refers to a logical entity used for communication with a base station (e.g., over one or more carriers) , and in some context, may also refer to a portion of a geographic coverage area (e.g., a sector) over which the logical entity operates. An identifier (e.g., a cell identity) may be associated with a cell to distinguish the cell from another cell. A UE 110 may register and communicate with one or more cells 122 (e.g., serving cells) while monitoring other cells 122 (e.g., neighbor cells) .

The core network 130 may include a network of entities providing user authentication, voice/multimedia communications, Internet Protocol (IP) connectivity, and/or other application services. These entities may be referred to as nodes, servers, gateways, functions, or other suitable terminologies. Examples of the core network 130 may include an evolved packet core (EPC) in a LTE network, a 5G Core (5GC) in a 5G or NR network, or generally, other packet based network architecture. The core network 130, such as in 5GC, may separate user plane function from control plane function into different entities. The user plane generally handles transfer of user data, whereas the control plane exchange of network control information. A base station 120 in a radio access network may communicate with an entity 132 to access services of the core network 130. The entity 132 may incorporate a mobility management entity (MME) and/or a serving gateway (SGW) , as in EPC, to implement control plane and/or user plane protocols. In other examples, the entity 132 may represent separate control plane or user plane functions, such as a core access and mobility management function (AMF) and/or a user plane function (UPF) in 5GC. The MME or AMF may provide control plane functionalities such as mobility, authentication, and/or bearer management for UEs 110 served by the base station 120. User data may be routed by the entity 132 through another entity 134, such as a PDN gateway (PGW) of EPC or a UPF of 5GC, connected to a packet data network (PDN) 140. The entity 134 may transport IP packets between the PDN 140 and a UE 110 accessing the PDN 140 via a base station 120 and the core network 130. The entity 134 may also provide IP address allocation as well as other functions. The core network 130 may also include other entities. For example, subscriber information or user profile may be stored in a server 136, such as a home subscriber server (HSS) , which may be queried, e.g., for user authentication, registration, or billing, etc.

In general, a packet data network may be any packet (e.g., IP) based network. A UE 110 may communicate with the PDN 140 for a variety of applications or services. Examples of the PDN 140 may include an operator’s service network, an IP Multimedia Subsystem (IMS) , or generally the Internet. The IMS may provide voice, video, or other multimedia applications, such as voice over IP (VoIP) call, across various types of communication networks.

The wireless communication system 100 may represent a packet-based network that operates according to various layered protocol stacks. Multiple protocol layers (or sublayers) may reside in a UE 110, a base station 120, and an entity of a core network 130. For example, in the user plane, a Packet Data Convergence Protocol (PDCP) layer, with counterparts residing in a UE 110 and a base station 120, may provide wireless communication service for user data via data radio bearers (DRBs) . Below PDCP may sit a Radio Link Control (RLC) layer, followed by a Medium Access Control (MAC) layer, and lastly by a Physical (PHY) layer, with counterparts residing in the UE 110 and the base station 120. In some examples (such as in NR) , a Service Data Adaptation Protocol (SDAP) layer may be interfaced between an upper protocol stack (e.g., IP) and the PDCP, for example, to handle mapping between quality of service (QoS) flows and data radio bearers. The SDAP, PDCP, RLC, and MAC layer may correspond to sublayers of “Layer 2” (or Data Link Layer) in terms of Open Systems Interconnection (OSI) model, and the PHY layer the “Layer 1” (or Physical Layer) . The SDAP layer may map between a QoS flow and a data radio bearer (DRB) and may also perform other QoS related operations. The PDCP layer may handle transfer of user data, header compression, in-sequence delivery, duplication detection, etc. The RLC layer may perform transfer of upper layer PDUs according to transmission modes, error correction through automatic repeat request (ARQ) , segmentation/concatenation, etc. The MAC layer may handle multiplexing of logical channels into transport channels and may schedule uplink/downlink transmission or reception at the PHY layer. The MAC may also use hybrid automatic repeat request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. The PHY layer may transmit information from MAC transport channels over the air interface. The PHY layer may also handle various aspects of power control, link adaptation, cell search, etc.

In the control plane, at a UE 110, an Non-Access Stratum (NAS) layer may lie on top of a Radio Resource Control (RRC) layer. The NAS layer may handle connection or session management between the UE 110 and a core network 130, whereas the RRC layer may handle radio resource management between the UE 110 and a base station 120. The RRC layer may correspond to “Layer 3” (or Network Layer) in the OSI model. The RRC layer may perform RRC connection management (including establishment, configuration, maintenance, and/or release) between the UE 110 and the base station 120, data and signaling radio bearer management, system information broadcast, mobility management, etc. In addition, the RRC layer may encapsulate and pass NAS messages between the UE 110 and the core network 130. For a respective peer layer (RRC or NAS) at the UE 110, a counterpart RRC layer may reside in the base station 120 and a counterpart NAS layer in an entity of the core network 130 (e.g., entity 132) . Below the RRC, a PDCP layer may transfer NAS/RRC messages via signaling radio bearers (SRBs) . Similar to the user plane, the PDCP may then be followed by RLC, MAC, and PHY, as generally described above with respect to the user plane.

The protocol stacks can provide for a variety of channels of communications. For examples, a set of “logic channels” may be provided for user and control data transfer between an RLC layer and a MAC layer; a set of “transport channels” between a MAC layer and a PHY layer; a set of “physical channels” may carry physical layer data and/or signals over the wireless medium (e.g., over the air interface) between a UE 110 and a base station 120. Generally speaking, a layer may receive, as an input, a service data unit (SDU) from a layer above, generate one or more protocol data units (PDUs) , e.g., by adding headers to the received SDU, and pass the generated PDUs to a layer below for further processing.

Besides communicating with a wireless wide area network (WWAN) , a UE110 may communicate with a wireless local area network (WLAN) , such as a Wireless-Fidelity (Wi-Fi) network. A WLAN 150 may include a wireless access point (AP) , such as a wireless “hotspot” or “router” coupled to the Internet. A user device served by a wireless access point may also be referred to as an access terminal (AT) . An AP 152 may wirelessly communicate with a UE 110 and may relay packetized communication data (e.g., IP packets) between the UE 110 and the Internet (or another AT) . A WWAN (e.g., the core network 130) may support inter-networking (including aggregation) with a WLAN, and a UE 110 may communicate with both a base station 120 and an AP 152.

For illustrative purposes, the following examples and figures may be described with reference to the user or network devices of FIG. 1; however, other types of user or network devices may be used in same or other examples without limiting the scope of the present disclosure.

FIG. 2 illustrates an example of system architecture 200 for non-standalone and standalone NR communications. The system architecture 200 comprises various communication devices and entities as generally described in FIG. 1, including elements of an LTE network and an NR network. An NR cell may serve a UE using NR waveform and radio protocol in a standalone (SA) mode or a non-standalone (NSA) mode. Some dual-mode NR cells may support both modes (SA and NSA) , for example, serving some UEs in NSA mode and other UEs in SA mode.

In NSA mode, an NR cell is anchored by an LTE cell with an LTE core network providing network services. From a UE’s perspective, the UE may be in dual connectivity with the anchor LTE cell in a Primary Cell Group (PCG) and the NR cell in a Secondary Cell Group (SCG) . Between the LTE core network and a UE, data traffic to/from the UE may path through both the LTE cell and the NR cell (with different radio interfaces respectively) . In one aspect, a UE 210 may connect to an LTE cell 220 which is connected to an LTE core network, EPC 230. The UE 210 may be in an RRC connected state and the network may know that the UE 210 has an NR NSA capability. An LTE base station (e.g., an eNB) associated with the LTE cell 220 may configure the UE 210 for NR cell measurement. The UE 210 may detect Primary Synchronization Signal (PSS) /Secondary Synchronization Signal (SSS) of an NR cell 225 and decode Physical Broadcast Channel (PBCH) of the NR cell 225 to receive a Master Information Block (MIB) of the NR cell 225. The PSS/SSS and PBCH may be contained in a Synchronization Signal Block (SS Block or SSB) . The MIB of an NR cell may provide basic system identification and configuration of the NR cell; however, a UE may not be able to access the NR cell (e.g., random access, network registration, etc. ) based on MIB alone. The LTE base station, via the LTE cell 220 not the NR cell 225, may provide the other types of system information of the NR cell 225, such as Remaining Minimum System Information (RMSI) and Other System Information (OSI) , to the UE 210 using LTE dedicated signaling. Through inter-base-station interface/connection, the LTE base station may obtain such (non-MIB) system information of the NR cell 225 from an NR base station (e.g., a gNB) associated with the NR cell 225. The RMSI may include a System Information Block 1 (SIB1) , which may contain additional parameters for the UE 210 to access the NR cell 225. For example, SIB1 may contain information relevant when evaluating if a UE is allowed to access a cell and define the scheduling of other system information. The SIB1 may also contain radio resource configuration information that is common for all UEs and barring information applied to the unified access control. Based on the system information (e.g., SIB1) , the UE 210 may know how to access the NR cell 225, and initiate a random access procedure on a Random Access Channel (RACH) of the NR cell 225. After a successful random access, the NR cell 225 may be added to the LTE SCG with the LTE cell 220 (in the LTE PCG) being the anchor cell.

In SA mode, an NR cell with a 5GC core network may provide NR services without relying on an LTE network, and thus traffic and control to/from a UE stays within the NR network. In an aspect, the NR cell 225, connected to a 5G core network, 5GC 235, may be capable of SA mode. In some deployments, the NR cell 225 may be a dual-mode cell capable of both SA mode and NSA mode operations. A UE 215 may select the NR cell 225 and receive a MIB (e.g., by decoding a PBCH carrying the MIB) from the NR cell 225. The MIB may contain information on whether SIB1 is configured and/or how to decode a Physical Downlink Shared Channel (PDSCH) carrying SIB1, such as a configuration of a common Control Resource Set (CORESET) , e.g., CORESET0, and a common search space, e.g., Search Space 0, for a Physical Downlink Control Channel (PDCCH) that schedules the PDSCH for the SIB1. The UE 215 may decode the over-the-air PDCCH/PDSCH to obtain the SIB1. If cell selection and access criteria are satisfied based on the content of SIB1, the UE 215 may access the NR cell 225 and register with the 5GC 235 for NR services. In SA mode, the UE 215 may access core network services provided by the 5GC 235.

FIG. 3 illustrates an example of a flowchart 300 of switching from NSA node to SA mode in accordance with the present disclosure. A UE 110 (or its components) may perform the flowchart 300. The UE 110 may be a dual-mode UE capable of NSA and SA operations for NR.

As generally described with reference to FIG. 2, the SA mode may differ from the NSA mode in the way how a UE gets SIB1 of an NR cell (which contains parameters on cell selection, random access, etc. ) : For NSA mode, the UE may obtain SIB1 (and other SIBs) from dedicated LTE signaling (e.g., via LTE RRC messages) of an anchor LTE cell, while for SA mode, the UE may obtain SIB1 by decoding PDCCH/PDSCH associated with SIB1 transmission (as broadcast by the NR cell) . The MIB of the NR cell may contain information for the PDCCH scheduling SIB1 PDSCH transmission. In both NSA mode and SA mode, a UE may decode a PBCH to receive MIB from the NR cell.

Since a dual-mode NR cell may serve both SA mode UEs and NSA mode UEs. The NR cell may broadcast SIB1 over the air (via PDSCH) , although for NSA UEs, SIB1 message may be delivered through LTE RRC dedicated message by an anchoring LTE cell. On the other hand, an NSA-only NR cell will likely not broadcast SIB1. Thus a UE may determine that an NR cell may support SA mode in addition to NSA mode (therefore a dual-mode cell) if the UE can successfully decode SIB1 via PDCCH/PDSCH transmitted from the NR cell over the air. In this case, for a UE that has connected to the NR cell in NSA mode but prefers SA mode, the UE may detach and deactivate LTE, and then camp on the NR cell and try to obtain SA NR service on the UE’s own initiatives rather than waiting for a redirection signaling by the LTE network or the operator.

At 310, a UE may be in NSA mode, connecting to an anchor LTE cell and an NR cell in dual connectivity, as generally described with reference to FIG. 2. Since a UE in NSA mode is served by an LTE core network (e.g., EPC 230 in FIG. 2) , the UE may not take advantage of newer advanced network features provided by a 5G core network (e.g., 5GC 235 in FIG. 2) such as network slicing, network function virtualization, etc. Thus, it may be beneficial for a UE capable of dual-mode operations to switch to SA mode sooner rather than staying in NSA mode. In some cases, an operator may implement a network-initiated signaling to disconnect a UE in NSA mode from LTE and instruct the UE to connect an NR cell in SA mode, for example, via an LTE RRC connection release message and/or other dedicated messages. However, in many cases, the network-initiated mode switching may not be responsive faster enough, or its timing may be uncertain, thus a UE in NSA mode may proactively attempt to identify a dual-mode NR cell and switch to SA mode.

At 320, the UE may determine whether SA mode is preferred. A UE may be provided with a configuration (e.g., an “SA preferred mode” ) indicating whether or not to prefer SA mode over NSA mode (or vice versa) . The configuration may be provided or implied by operator policy, UE power policy, or NR-based services (such as network slicing functionality) . If the SA mode is not preferred, the UE may proceed to 370, staying on NSA mode and waiting to check another cell (such as when a new NR SCG cell is added in NSA mode) . Otherwise (if the SA mode is preferred) , the UE may determine, at its own initiatives, whether to switch to SA mode for the NR cell (currently connected to by the UE in NSA mode) .

The UE-initiated mode-switching may be determined based on decoding for SIB1 of the NR cell, as well as (optionally) satisfactions of certain criteria regarding the NR cell. Some of the exemplary steps are elaborated below with reference to 325 to 350 of the flowchart 300.

At 325, the UE may read MIB of the NR cell. The MIB may have been cached when UE acquires the NR cell for NSA mode, or the UE may decode a PBCH (e.g., in an SSB) of the NR cell to receive the MIB.

At 330, based on the (content of) MIB, the UE may check whether SIB1 is configured. In one respect, an SSB offset value (e.g., “k _ssb” ) based on an “ssb-SubcarrierOffset” parameter in the MIB may indicate whether SIB1 is configured by the MIB. For instance, SIB1 is not scheduled (and the corresponding CORESET0 is not present) when k _ssb is larger than 23 for Frequency Range 1 or larger than 11 for Frequency Range 2; or may be scheduled otherwise. In addition, based on a “pdcch-ConfigSIB1” parameter in the MIB, the UE may determine configurations for common CORESET and Search Space for a PDCCH scheduling a PDSCH carrying SIB1. If SIB1 is not configurated, the UE may proceed to 370 staying on NSA mode; otherwise, the UE may proceed to 335, attempting to decode SIB1 based on the information/configuration provided in the MIB.

At 340, the UE may determine whether the SIB1 is successfully decoded. From an aspect, the UE may try to decode a PDCCH/PDSCH for SIB1 within a time duration (potentially involving multiple decoding trials) . If no SIB1 is decoded successfully, the UE may proceed to 370. The time duration may be set in view of a (minimum) periodicity of SIB1 transmission, such as a 80-millisecond (ms) margin over a full SIB1 period (e.g., 160ms) , totaling 240ms.

Having successfully decoded the SIB1, at 350, the UE may check whether the NR cell may be camped and not barred for access, based on the (content of) SIB1. The NR cell may be camped on by the UE if certain cell selection criteria are met. A field “cellSelectionInfo” in SIB1 may specify various parameters for cell selection. The UE may measure the NR cell and check whether the NR cell may meet certain cell selection criteria. An example of cell selection for NR may be given in 3GPP Technical Specification TS 38.304 (Rel. 15) section 5.2. Furthermore, access to a cell may be restricted by the operator, and thus the UE may check whether the NR cell is barred for access. A field “cellAccessRelatedInfo” in SIB1, and additionally or alternatively “cellBarred” in MIB, may indicate whether the NR cell is barred (or reserved) . An example of cell reservations and access restrictions for NR is given in TS 38.304 (Rel. 15) section 5.3. In addition, the UE may optionally check whether the NR cell is in a “blacklist” (e.g., an “SA cell blacklist” ) which may preclude the UE from connecting to a cell in the blacklist in SA mode. The UE may compile the blacklist based on cell access or mode switching history. For example, the UE may place an NR cell in the backlist if the UE fails to successfully switch to SA mode for the cell in the past for a variety of reasons, such as RACH failure for some times or attachment rejection. If the NR cell cannot be camped or is barred (including blacklisted) , the UE may proceed to 370, remaining in the NSA mode. In this case, the UE may add the NR cell into the SA cell blacklist.

Otherwise, if the NR cell can be camped and is not barred, the UE may switch to SA mode, at 360. The UE may detach from LTE, select to NR for SA mode, and/or perform NR registration. The LTE detachment may trigger LTE RRC release, and the NR cell as SCG may also be deactivated. The UE may camp on the NR cell and initiate NR NAS registration to register with the 5GC core network for NR network services.

FIG. 4 illustrates an example of a call flow for switching from NSA mode to SA mode in accordance with the present disclosure. The call flow reflects various aspects of the flowchart 300 described with reference to FIG. 3, and in particular, illustrates some network signaling aspects for the mode switching.

Before the mode switching, a UE 410 may be connected to an LTE cell 420 and registered with an LTE core network, EPC 430. At 440, the UE 410 may operate in NSA mode, connecting to an NR cell 425 (in an LTE SCG) at radio level but served by the LTE core network, EPC 430. At 450, the UE 410 may determine whether to switch to SA mode for the NR cell 425, as generally described above with reference to FIG. 3. From one aspect, the mode-switching determination may depend on the outcome of decoding SIB1 channels (e.g., PDCCH/PDSCH for the SIB1) from the NR cell 425, and may further depend on one or more criteria (e.g., cell selection, access restriction) based on parameters signaled by the SIB1. For example, the UE 410 may determine to switch to the SA mode if SIB1 is available (by a successfully SIB1 decoding) , cell selection criteria are met based on SIB1 (e.g., cellSelectionInfo from SIB1) , and the NR cell 425 is not barred or blacklisted.

The UE 410 may then try to disconnect from the LTE network, e.g., by sending a network detachment message 451 (e.g., “LTE NAS Detach” ) to the EPC 430, and in response, the UE may receive from the LTE cell 420 a radio resource release message 452 (e.g., “LTE RRC Release” ) . As a result, the NR cell 425 may be deactivated as an LTE SCG cell, and the UE 410 may be in an LTE RRC idle state.

While disconnecting the NR cell 425 in NSA mode, the UE 410 may separately attempt to connect to the NR cell 425 in SA mode. The UE 410 may first camp on the NR cell 425 and attempt to register with a 5G core network, 5GC 435, associated with the NR cell 425. In particular, the UE 410 may send a network registration request 453 (e.g., “NR NAS Registration Request” ) to the 5GC 435. If the registration is successful, the 5GC 435 may reply a registration acceptance message 454 (e.g., “NR NAS Registration Accept” ) to the UE 410. The UE may reuse the RACH information obtained from the decoded SIB to initiate random access and registration.

At 460, after successful NR network registration, the UE 410 is now in SA mode and may access NR network service (such as network slicing, etc. ) provided by the 5GC 435. Different from the previous NSA mode, the data/traffic path may be between the UE 410 and the 5GC 435 via the NR cell 425 in SA mode.

FIG. 5 illustrates an example of a method 500 of wireless communication by a user equipment in accordance with the present disclosure. The method 500 may encompass various aspects of the flowchart and call flow described with reference to FIG. 3 and FIG. 4. A UE (or one or more of its components) , e.g., UE 110 in FIG. 1, may implement the method 500 using hardware, firmware, or software, or a combination thereof.

At 510, a UE may connect to an LTE cell. The LTE cell may be connected to an LTE core network.

At 520, the UE may connect to an NR cell in a non-standalone mode, wherein the LTE cell is an anchor cell for the NR cell. As generally described with reference to FIG. 2 and FIG. 3, in NSA mode, although the UE may receive an MIB from the NR cell directly over the air (e.g., by decoding a PBCH channel of the NR cell) , the UE may only receive the other system information, such as RMSI (including SIB1) and OSI, of the NR cell indirectly through the LTE cell (e.g., via LTE RRC dedicated messages) . As an anchor cell for the NR cell in NSA mode, the LTE cell may terminate network control, with the NR cell providing additional radio interface for communications as an LTE SCG cell.

In NSA mode, the UE may be served by an LTE core network that may lack certain advanced or newer features offered by a newer NR core network. Thus, a dual-mode UE (capable of both NSA and SA operation) may attempt to switch to SA mode to connect to an NR core network via the NR cell. To opportunistically explore the possibility that an NR cell currently connected in NSA mode by the UE may also support SA mode (thus a dual-mode NR cell) , the UE may proactively switch to the SA mode, for example, as described with reference to FIG. 3 and FIG. 4. In addition, the UE-initiated mode switching may be faster, more responsive to mobility, than network-initiated mode switching.

At 530, the UE may determine whether to switch to a standalone mode for the NR cell, for example, as described with reference to FIG. 3. The UE may jointly or separately consider a variety of configurations and criteria. From an aspect, the UE may determine whether to switch to the SA mode based on a configuration (e.g., “SA preferred mode” ) indicating a preference for the SA mode or the NSA mode. The UE may only attempt to switch to the SA mode if the configuration indicates a preference for the SA mode.

From another aspect, the UE may determine whether to switch to the SA mode based on a decoding attempt for a system information block (SIB) transmitted from the NR cell. Instead of relying on the anchor LTE cell to relay the NR cell’s system information, the UE may try to decode over the air channels transmitted by the NR cell to receive system information directly. The SIB, such as an SIB1 may contain information, not present in MIB, such as for cell camping (e.g., cell selection) and/or cell access restriction. A successful SIB decoding may indicate the NR cell likely supports dual mode operation. To directly receive the SIB, the UE may determine whether the SIB is configured based on a master information block of the NR cell. The MIB may indicate whether the SIB1 is scheduled and, if so, where to find a PDCCH scheduling a PDSCH for SIB1. The UE may then decode a channel for the SIB (e.g., by demodulating and decoding the SIB channel) if the SIB is configured.

If the UE fails to decode the SIB, for example, within certain time duration, the UE may determine not to switch to the SA mode; otherwise the UE may determine to switch to the SA mode or further check one or more additional conditions. Based on the (content of) SIB, the UE may determine whether the NR cell meets a cell selection criterion and/or whether the NR cell is barred or restricted for access, for example, as described with reference to FIG. 3.

In addition to checking the SIB, the UE may further determine whether to switch to the SA mode based on a blacklist barring one or more cells for the SA mode. The blacklist may be created or maintained based on cell access/mode-switching history, operator policy, user preference, etc. The UE may check whether the NR cell is among the blacklist, and if so, may determine not to switch to the SA mode for the NR cell.

At 540, the UE may connect to the NR cell in the SA mode if the SA mode is determined; otherwise the UE may stay in the NSA mode. In one respect, the UE may detach from the LTE cell and register with an NR core network via the NR cell. As elaborated with reference to FIG. 4, the UE may exchange various messages with the LTE core network (to be de-registered) and the NR core network (to be registered) . In SA mode, the UE may access network services provided by the NR core network.

FIG. 6 illustrates an example of an apparatus 600 of wireless communication in accordance with the present disclosure. The apparatus 600 may include a receiver 610, a transmitter 620, and a NR-mode controller 630, and may perform various aspects of the method 500 described with reference to FIG. 5. The apparatus 600 may be embodied by, or reside within, a UE 110 with reference to FIG. 1.

The receiver 610 may be configured to receive signals or channels carrying information such as packets, user data, or control information associated with various information channels. Information may be passed on to other components of the apparatus. The receiver 610 may utilize a single antenna or a set of multiple antennas.

The transmitter 620 may be configured to transmit signals or channels generated by other components of the apparatus. In some examples, the transmitter 620 may be collocated with a receiver 610 in a transceiver module. The transmitter 620 may utilize a single antenna or a set of multiple antennas.

The receiver 610 and transmitter 620 (or a transceiver incorporating both) may be coupled to the NR-mode controller 630 and may provide means for communication between the apparatus 600 with a base station.

The NR-mode controller 630 may be a baseband modem or an application processor or may illustrate aspects of a baseband or application processor. The NR-mode controller 630 or at least some of its various sub-components may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. Software may comprise codes or instructions stored in a memory or like medium that is connected or in communication with the processor described above. The codes or instructions may cause the processor, the apparatus 600, or one or more components thereof to perform various functions described herein.

The NR-mode controller 630 may control, coordinate, or execute various functions supporting switching from NSA mode to SA mode for NR communications. The NR-mode controller 630 may further include an LTE communicator 632, a mode-switching logic 634, and an NR communicator 636.

The LTE communicator 632 may provide means for connecting to an LTE cell and may, for example, be configured to perform the method 500 at 510 described with reference to FIG. 5. The LTE communicator 632 may also be configured to receive from the LTE cell a remaining minimum system information of an NR cell. It may also be configured to send detachment request to an LTE core network via the LTE cell.

The NR communicator 636 may provide means for connecting to an NR cell in either an NSA mode or an SA mode, and may, for example, be configured to perform the method 500 at 520 and 540 described with reference to FIG. 5. The NR communicator 636 may be configured to decode a MIB transmitted from the NR cell. The NR communicator 636 may also be configured to decode a system information block (SIB) , e.g., SIB1, transmitted from the NR cell. In addition, the NR communicator 636 may also be configured to register with an NR core network via the NR cell.

The mode-switching logic 634 may coordinate the LTE communicator 632 and the NR communicator 636 in providing communication services in NSA or SA mode or a switching between the two modes. In particular, the mode-switching logic 634 may provide means for determining whether to switch to a standalone mode for the NR cell, and may, for example, be configured to perform the method 500 at 530 described with reference to FIG. 5.

From one aspect, whether to switch to the SA mode may be determined based on a configuration indicating a preference for the SA mode or the NSA mode. From another aspect, whether to switch to the SA mode may be determined based on a decoding attempt for a system information block transmitted from the NR cell. To decode the SIB, the mode-switching logic 634 may be configured to determine whether the SIB is configured based on a master information block (MIB) of the NR cell. If the SIB is configured, the mode-switching logic 634 may cause the NR communicator 636 to decode a channel for the SIB. The mode-switching logic 634 may determine not to switch to the SA mode, for example, if the SIB is not configured or if the SIB (despite being configured by the MIB) is not successfully decoded (e.g., during a time duration) . If the SIB is available, the mode-switching logic 634 may be configured to determine whether to switch to the SA mode based on the (content of) SIB: for example, whether the NR cell meets a cell selection criterion, and/or whether the NR cell is barred or restricted for access. From yet another aspect, whether to switch to the SA mode may be determined based on a blacklist barring one or more cells for the SA mode.

FIG. 7 illustrates an example of a device 700 in accordance with the present disclosure. The device 700 may be an example of a UE 110 in FIG. 1 or components thereof, which may embody various aspects of the apparatus 600 described with reference to FIG. 6. The device 700 may comprise UE NR-mode controller 710, processor 720, memory 730, software 735, transceiver 740, antenna 745, and I/O controller 750. These components may be coupled or in electronic communication via one or more buses (e.g., bus 705) . The device 700 may communicate wirelessly with one or more base stations 120.

UE NR-mode controller 710 may perform various functions supporting switching from NSA mode to SA mode for NR communications. For example, the UE NR-mode controller 710 may be configured to connect to an LTE cell, connect to an NR cell in NSA mode wherein the LTE cell is an anchor cell for the NR cell, determine whether to switch to SA mode for the NR cell, and/or connect to the NR cell in SA mode if the SA mode is determined. In some examples, the UE NR-mode controller 710 may implement the NR-mode controller 630 described with reference to FIG. 6. Generally speaking, the UE NR-mode controller 710 may utilize processor 720 and memory 730 to execute its functionalities.

Processor 720 may include an intelligent hardware device, (e.g., a general-purpose processor, a DSP, a central processing unit (CPU) , a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some cases, processor 720 may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into processor 720. Processor 720 may be configured to execute computer-readable instructions (e.g., software 735) stored in a memory (e.g., memory 730) to perform various functions.

Memory 730 may include random access memory (RAM) and/or read only memory (ROM) . In some cases, the memory 730 may contain, among other things, a basic input/output system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices. The memory 730 may store computer-readable, computer-executable software 735 including instructions that, when executed, cause the processor 720 (or the device 700 generally) to perform various functions described herein.

Software 735 may include codes implementing aspects of the present disclosure, e.g., described with reference to FIGs. 3, 4, 5 and 6. For example, the software 735 may include codes for connecting to an LTE cell, connecting to an NR cell in NSA mode wherein the LTE cell is an anchor cell for the NR cell, determining whether to switch to SA mode for the NR cell, and/or connecting to the NR cell in SA mode if the SA mode is determined. Software 735 may be stored in a non-transitory computer-readable medium such as system memory or other memory. In some cases, the software 735 may not be directly executable by the processor but may cause a computer (e.g., when compiled and executed) to perform functions described herein.

Transceiver 740 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver 740 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 740 may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets from signals received from the antennas. In some examples, the transceiver 740 may include both the receiver 610 and the transmitter 620 described with reference to FIG. 6.

In some cases, the wireless device may include a single antenna 745. However, in some cases the device may have more than one antenna 745, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

I/O controller 750 may manage input and output signals for the device 700. I/O controller 750 may also manage peripherals not integrated into the device 700. In some cases, I/O controller 750 may represent a physical connection or port to an external peripheral. In some cases, I/O controller 750 may utilize an operating system such as

or another known operating system. In other cases, I/O controller 750 may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or other device. In some cases, I/O controller 750 may be implemented as part of a processor. In some cases, a user may interact with the device 700 via I/O controller 750 or via hardware components controlled by I/O controller 750.

The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “exemplary” used herein means “serving as an example, instance, or illustration, ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

As used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an exemplary step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. ”

As used herein, the conjunction “or” shall generally be interpreted as “inclusive” unless the context indicates otherwise. For example, “A or B” would generally mean “either A, or B, or both” (but not necessarily “either A, or B, but not both” ) ; in other words, the presented alternatives ( “A” and “B” ) need not necessarily be mutually exclusive. Certain context, however, can indicate an “exclusive or, ” as in “whether A or not, ” for example.

Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) .

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

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media can include random access memory (RAM) , read-only memory (ROM) , electrically erasable programmable read only memory (EEPROM) , compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, digital subscriber line, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include CD, laser disc, optical disc, digital versatile disc (DVD) , floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

A method of wireless communication, comprising:

connecting to a Long-Term Evolution (LTE) cell;

connecting to a New Radio (NR) cell in a non-standalone (NSA) mode, wherein the LTE cell is an anchor cell for the NR cell;

determining whether to switch to a standalone (SA) mode for the NR cell; and

connecting to the NR cell in the SA mode if the SA mode is determined.
The method of claim 1, wherein said connecting to the NR cell in the NSA mode comprises:

receiving from the LTE cell a remaining minimum system information (RMSI) of the NR cell.
The method of claim 1, wherein whether to switch to the SA mode is determined based on a configuration indicating a preference for the SA mode or the NSA mode.
The method of claim 1, wherein whether to switch to the SA mode is determined based on a decoding attempt for a system information block (SIB) transmitted from the NR cell.
The method of claim 4, wherein said determining whether to switch to the SA mode comprises:

determining whether the SIB is configured based on a master information block (MIB) of the NR cell; and

decoding a channel for the SIB if the SIB is configured.
The method of claim 4, wherein said determining whether to switch to the SA mode further comprises:

determining whether the NR cell meets a cell selection criterion based on the SIB.
The method of claim 4, wherein said determining whether to switch to the SA mode further comprises:

determining whether the NR cell is barred or restricted for access based on the SIB.
The method of claim 1, wherein whether to switch to the SA mode is determined based on a blacklist barring one or more cells for the SA mode.
The method of claim 1, wherein said connecting to the NR cell in the SA mode comprises:

detaching from the LTE cell; and

registering with an NR core network via the NR cell.
A user equipment (UE) , comprising:

a memory; and

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

connect to a Long-Term Evolution (LTE) cell;

connect to a New Radio (NR) cell in a non-standalone (NSA) mode, wherein the LTE cell is an anchor cell for the NR cell;

determine whether to switch to a standalone (SA) mode for the NR cell; and

connect to the NR cell in the SA mode if the SA mode is determined.
The UE of claim 10, wherein the one or more processors configured to connect to the NR cell in the NSA mode comprises the one or more processors configured to:

receive from the LTE cell a remaining minimum system information (RMSI) of the NR cell.
The UE of claim 10, wherein whether to switch to the SA mode is determined based on a configuration indicating a preference for the SA mode or the NSA mode.
The UE of claim 10, wherein whether to switch to the SA mode is determined based on a decoding attempt for a system information block (SIB) transmitted from the NR cell.
The UE of claim 13, wherein the one or more processors configured to determine whether to switch to the SA mode comprises the one or more processors configured to:

determine whether the SIB is configured based on a master information block (MIB) of the NR cell; and

decode a channel for the SIB if the SIB is configured.
The UE of claim 13, wherein the one or more processors configured to determine whether to switch to the SA mode further comprises the one or more processors configured to:

determine whether the NR cell meets a cell selection criterion based on the SIB.
The UE of claim 13, wherein the one or more processors configured to determine whether to switch to the SA mode further comprises the one or more processors configured to:

determine whether the NR cell is barred or restricted for access based on the SIB.
The UE of claim 10, wherein whether to switch to the SA mode is determined based on a blacklist barring one or more cells for the SA mode.
The UE of claim 10, wherein the one or more processors configured to connect to the NR cell in the SA mode comprises the one or more processors configured to:

detach from the LTE cell; and

register with an NR core network via the NR cell.
An apparatus of wireless communication, comprising:

means for connecting to a Long-Term Evolution (LTE) cell;

means for connecting to a New Radio (NR) cell in a non-standalone (NSA) mode, wherein the LTE cell is an anchor cell for the NR cell;

means for determining whether to switch to a standalone (SA) mode for the NR cell; and

means for connecting to the NR cell in the SA mode if the SA mode is determined.
The apparatus of claim 19, wherein the means for connecting to the NR cell in the NSA mode comprises:

means for receiving from the LTE cell a remaining minimum system information (RMSI) of the NR cell.
The apparatus of claim 19, wherein whether to switch to the SA mode is determined based on a configuration indicating a preference for the SA mode or the NSA mode.
The apparatus of claim 19, wherein whether to switch to the SA mode is determined based on a decoding attempt for a system information block (SIB) transmitted from the NR cell.
The apparatus of claim 22, wherein the means for determining whether to switch to the SA mode comprises:

means for determining whether the SIB is configured based on a master information block (MIB) of the NR cell; and

means for decoding a channel for the SIB if the SIB is configured.
The apparatus of claim 22, wherein the means for determining whether to switch to the SA mode further comprises:

means for determining whether the NR cell meets a cell selection criterion based on the SIB.
The apparatus of claim 22, wherein the means for determining whether to switch to the SA mode further comprises:

means for determining whether the NR cell is barred or restricted for access based on the SIB.
The apparatus of claim 19, wherein whether to switch to the SA mode is determined based on a blacklist barring one or more cells for the SA mode.
The apparatus of claim 19, wherein the means for connecting to the NR cell in the SA mode comprises:

means for detaching from the LTE cell; and

means for registering with an NR core network via the NR cell.
A non-transitory computer-readable medium having instructions stored thereon, the instructions comprising codes executable for a user equipment to perform:

connecting to a Long-Term Evolution (LTE) cell;

connecting to a New Radio (NR) cell in a non-standalone (NSA) mode, wherein the LTE cell is an anchor cell for the NR cell;

determining whether to switch to a standalone (SA) mode for the NR cell; and

connecting to the NR cell in the SA mode if the SA mode is determined.
The non-transitory computer-readable medium of claim 28, wherein the codes for connecting to the NR cell in the NSA mode comprises:

codes for receiving from the LTE cell a remaining minimum system information (RMSI) of the NR cell.
The non-transitory computer-readable medium of claim 28, wherein whether to switch to the SA mode is determined based on a configuration indicating a preference for the SA mode or the NSA mode.
The non-transitory computer-readable medium of claim 28, wherein whether to switch to the SA mode is determined based on a decoding attempt for a system information block (SIB) transmitted from the NR cell.
The non-transitory computer-readable medium of claim 31, wherein the codes for determining whether to switch to the SA mode comprises:

codes for determining whether the SIB is configured based on a master information block (MIB) of the NR cell; and

codes for decoding a channel for the SIB if the SIB is configured.
The non-transitory computer-readable medium of claim 31, wherein the codes for determining whether to switch to the SA mode further comprises:

codes for determining whether the NR cell meets a cell selection criterion based on the SIB.
The non-transitory computer-readable medium of claim 31, wherein the codes for determining whether to switch to the SA mode further comprises:

codes for determining whether the NR cell is barred or restricted for access based on the SIB.
The non-transitory computer-readable medium of claim 28, wherein whether to switch to the SA mode is determined based on a blacklist barring one or more cells for the SA mode.
The non-transitory computer-readable medium of claim 28, wherein the codes for connecting to the NR cell in the SA mode comprises:

codes for detaching from the LTE cell; and

codes for registering with an NR core network via the NR cell.