Independent mode PLMN selection

Abstract

A computer-readable storage medium including an instruction set for operating a processor, a user equipment (UE) configured to perform operations, and an integrated circuit. The operations include: receiving a signal broadcast by a cell of a New Radio (NR) network; determining, based on the received signal, whether the cell is configured for Standalone (SA) operation for NR; when the cell is configured for the SA operation for NR, locally storing, at the UE, a first indication that the cell is configured for the SA operation for NR; when the cell is not configured for the SA operation for NR, locally storing, at the UE, a second indication that the cell is configured for Non-Standalone (NSA) operation for NR; and initiating a Public Land Mobile Network (PLMN) search process, wherein the PLMN search process includes a frequency scan based on the first indication or the second indication.

Description

Background Art

[0001] A user equipment (UE) may establish a connection with at least one of multiple different networks or network types. To establish a network connection and receive the full range of services that are typically available to the UE via the network connection, the UE may select a public land mobile network (PLMN) to camp on. PLMN selection has been identified as a source of latency and inefficiency. For example, the longer it takes for the UE to complete the PLMN selection process, the longer it takes for the UE to access network services. Additionally, performing operations associated with PLMN selection may cause the UE to experience power consumption. Accordingly, techniques configured to optimize PLMN selection are needed. Summary of the Invention

[0002] In some exemplary embodiments, a computer-readable storage medium including a set of instructions is provided that, when executed by a processor of a user equipment (UE), causes the processor to perform operations. The operations include: receiving a signal broadcast by a cell of a new radio (NR) network; determining, based on the received signal, whether the cell is configured for standalone (SA) operation for NR; when the cell is configured for the SA operation for NR, locally storing, at the UE, a first indication that the cell is configured for the SA operation for NR; when the cell is not configured for the SA operation for NR, locally storing, at the UE, a second indication that the cell is configured for non-standalone (NSA) operation for NR; and initiating a public land mobile network (PLMN) search process, wherein the PLMN search process includes a frequency scan based on the first indication or the second indication.

[0003] In other exemplary embodiments, a user equipment (UE) having a transceiver and a processor is provided. The transceiver is configured to communicate with one or more networks. The processor is configured to perform operations, the operations including: receiving a signal broadcast by a cell of a new radio (NR) network; decoding the signal to determine whether the cell is configured for standalone (SA) operation for NR; when the cell is configured for the SA operation for NR, locally storing, at the UE, a first indication that the cell is configured for the SA operation for NR; when the cell is not configured for the SA operation for NR, locally storing, at the UE, a second indication that the cell is configured for non-standalone (NSA) operation for NR; and initiating a public land mobile network (PLMN) search process, wherein the PLMN search process includes a frequency scan based on the first indication or the second indication.

[0004] In another exemplary embodiment, an integrated circuit is provided. The integrated circuit includes: circuitry configured to receive a signal broadcast by a cell of a New Radio (NR) network; circuitry configured to decode the signal to determine whether the cell is configured for Standalone (SA) operation for NR; circuitry configured to locally store, at the UE, a first indication that the cell is configured for the SA operation for NR when the cell is configured for the SA operation for NR; circuitry configured to locally store, at the UE, a second indication that the cell is configured for Non-Standalone (NSA) operation for NR when the cell is not configured for the SA operation for NR; and circuitry configured to initiate a Public Land Mobile Network (PLMN) search procedure, wherein the PLMN search procedure includes a frequency scan based on the first indication or the second indication. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 An exemplary network arrangement is shown in accordance with various exemplary embodiments.

[0006] Figure 2 An exemplary UE is shown in accordance with various exemplary embodiments.

[0007] Figure 3 A method for maintaining a Standalone (SA) Public Land Mobile Network (PLMN) database is shown in accordance with various exemplary embodiments.

[0008] Figure 4 A method for performing PLMN selection using an SA PLMN database is shown in accordance with various exemplary embodiments.

[0009] Figure 5 A method for implementing various techniques for performing PLMN selection when camped on a Radio Access Technology (RAT) below 5G New Radio (NR) is shown in accordance with various exemplary embodiments.

[0010] Figure 6 A method for transitioning from a currently camped LTE HPLMN to a 5G NR equivalent PLMN (ePLMN) or a 5G NR equivalent home PLMN (eHPLMN) is shown in accordance with various exemplary embodiments.

[0011] Figure 7 A method 700 for performing a PLMN search when UE 110 is camped on a Circuit Switched (CS) RAT is shown in accordance with various exemplary embodiments.

[0012] Figure 8a It shows a signaling diagram of the UE transitioning between the RRC idle state and the RRC connected state based on SIB1 when both a cell with SA capability and a cell with NSA capability exist.

[0013] Figure 8b It shows a signaling diagram of the UE transitioning between the RRC idle state and the RRC connected state based on MIB when both a cell with SA capability and a cell with NSA capability exist.

[0014] Figure 9 It shows a signaling diagram for generating a measurement report that does not include SA cells. Detailed implementation

[0015] Exemplary embodiments can be further understood with reference to the following description and the related drawings, where similar elements have the same reference numerals. The exemplary embodiments relate to public land mobile network (PLMN) selection.

[0016] The exemplary embodiments are described with reference to the UE. However, the reference to the UE is provided only for illustrative purposes. The exemplary embodiments can be used with any electronic component that can establish a connection with the network and is configured with hardware, software, and / or firmware for exchanging information and data with the network. Therefore, the UE described herein is used to represent any electronic component.

[0017] The exemplary embodiments are also described with reference to the 5G new radio (NR) radio access technology (RAT). When operating in the non-standalone (NSA) mode or the standalone (SA) mode of 5G, the UE can access 5G NR services. In the NSA mode, the UE can be configured with simultaneous connections to both the 5G NR RAT and the LTE RAT (e.g., dual connection). Those skilled in the art will understand that dual connection generally means that the UE is configured to communicate with cells associated with different RATs. For example, when in the NSA mode of 5G, the UE can achieve dual connection via the master cell group (MCG) corresponding to LTE and the secondary cell group (SCG) corresponding to 5G NR, and vice versa. Each cell group can include at least one cell for the corresponding RAT. Therefore, when operating in the NSA mode of 5G, the UE can be simultaneously connected to 5G NR and LTE.

[0018] In the SA mode of 5G, a UE can be connected to one RAT at a specific time. During operation, the network connection can be switched between different RATs (e.g., 5G NR, LTE, legacy, etc.). For example, at a first time, the network connection can use the 5G NR RAT via at least one NR cell. Subsequently, the UE and / or the network can cause the UE to switch from 5G NR to LTE. Thus, at a second time, the network connection can use the LTE RAT via at least one LTE cell. Therefore, when operating in the SA mode, a UE can use one RAT at a time for the network connection.

[0019] Exemplary embodiments relate to a UE operating in the SA mode and performing PLMN selection. PLMN selection generally involves the UE identifying one or more PLMNs that serve the geographical location of the UE and selecting a suitable PLMN from the identified set of PLMNs. A PLMN can include multiple different RATs and multiple cells that support different types of functions. For example, a PLMN can include a 5GNR RAT having one or more 5G NR cells that support SA functionality and one or more 5G NR cells that support only NSA functionality. PLMN selection can also include selecting a cell of the PLMN to be camped on. Thus, a UE operating in the SA mode and performing PLMN selection can perform operations related to identifying whether the cells of the PLMN support SA functionality.

[0020] In some exemplary embodiments, a UE can identify whether a 5G NR cell supports SA functionality based on the content of a system information block (SIB) broadcast by the 5G NR cell. For example, a 5G NR cell can broadcast SIB1, which is configured to be used by the UE for synchronization. If SIB1 includes a tracking area code, the UE can assume that the cell supports SA functionality. Alternatively, the absence of a tracking area code in SIB1 can indicate to the UE that the cell supports only primary secondary cell (PSCell) / secondary cell (SCell) functionality for the PLMN identified in SIB1. Those skilled in the art will understand that PSCell and SCell are associated with SCG and thus with NSA functionality. In other words, if the SIB1 broadcast by the 5G NR cell does not include a tracking area code, the UE can assume that the 5G NR cell supports only NSA functionality.

[0021] Exemplary embodiments are described with reference to a database that can be maintained and utilized by a UE during PLMN selection. Throughout this specification, this database may be referred to as the "SA PLMN database". The database may be configured to include one or more PLMN identifiers. For each PLMN identifier, the database may include one or more cell identifiers. For each cell identifier, the database may include an indication as to whether the cell identifier supports SA functionality. As will be explained in detail below, at a first time, the UE may collect this type of information for a geographical area and then store it in the SA PLMN database. When the UE returns to the geographical area at a second time, the UE may use the database to target certain 5G NR cells and / or frequencies. However, the reference to the term SA PLMN database is provided for illustrative purposes only, and different entities may refer to similar concepts by different names.

[0022] In a first aspect, an exemplary embodiment relates to managing the SA PLMN database. As described above, this may include determining whether a particular cell supports SA functionality. In a second aspect, an exemplary embodiment relates to utilizing the SA PLMN database and other exemplary techniques for PLMN selection. In a third aspect, an exemplary embodiment relates to utilizing the SA PLMN database and other exemplary techniques to transition from a lower RAT connection to a 5G NR connection. In a fourth aspect, an exemplary embodiment relates to differentiating between SA cells and NSA cells without utilizing SIB1. Specific examples of each of these exemplary aspects will be described in detail below.

[0023] Figure 1 An exemplary network arrangement 100 is shown in accordance with various exemplary embodiments. The exemplary network arrangement 100 includes a UE 110. Those skilled in the art will understand that the UE 110 can be any type of electronic component configured to communicate via a network, such as, for example, a mobile phone, a tablet computer, a desktop computer, a smart phone, a phablet, an embedded device, a wearable device, an Internet of Things (IoT) device, etc. It should also be understood that an actual network arrangement may include any number of UEs used by any number of users. Thus, for illustrative purposes, only an example with a single UE 110 is provided.

[0024] The UE 110 may be configured to communicate with one or more networks. In an example of the network configuration 100, the networks with which the UE 110 may communicate wirelessly are a 5G New Radio (NR) radio access network (5G NR-RAN) 120, an LTE radio access network (LTE-RAN) 122, and a wireless local area network (WLAN) 124. However, it should be understood that the UE 110 may also communicate with other types of networks, and the UE 110 may also communicate with the networks via a wired connection. Thus, the UE 110 may include a 5G NR chipset for communicating with the 5G NR-RAN 120, an LTE chipset for communicating with the LTE-RAN 122, and an ISM chipset for communicating with the WLAN 124.

[0025] The 5G NR-RAN 120 and the LTE-RAN 122 may be part of a cellular network that may be deployed by a cellular provider (e.g., Verizon, AT&T, Sprint, T-Mobile, etc.). These networks 120, 122 may include, for example, cells or base stations (NodeB, eNodeB, HeNB, eNBS, gNB, gNodeB, macro cell base stations, micro cell base stations, small cell base stations, femto cell base stations, etc.) that are configured to send and receive traffic from UEs equipped with appropriate cellular chipsets. The WLAN 124 may include any type of wireless local area network (WiFi, hotspots, IEEE 802.11x networks, etc.).

[0026] The UE 110 may be connected to the 5G NR-RAN 120 via the gNB 120A. The gNB 120A may be configured with the necessary hardware, software, and / or firmware to perform massive multiple-input multiple-output (MIMO) functions. Massive MIMO may refer to a base station that is configured to generate multiple beams for multiple UEs. During operation, the UE 110 may be within the range of multiple gNBs. Thus, simultaneously or alternatively, the UE 110 may also be connected to the 5G NR-RAN 120 via the gNB 120B. The reference to the two gNBs 120A, 120B is for illustrative purposes only. Exemplary embodiments may apply to any appropriate number of gNBs. Additionally, the UE 110 may communicate with the eNB 122A of the LTE-RAN 122 to transmit and receive control information for downlink and / or uplink synchronization with respect to the connection to the 5G NR-RAN 120.

[0027] Those skilled in the art will understand that any relevant process can be executed for the UE 110 to connect to the 5G NR-RAN 120. For example, as described above, the 5G NR-RAN 120 can be associated with a specific cellular provider where the UE 110 and / or its user have protocol and credential information (e.g., stored on the SIM card). When the presence of the 5G NR-RAN 120 is detected, the UE 110 can transmit the corresponding credential information to be associated with the 5G NR-RAN 120. More specifically, the UE 110 can be associated with a specific base station (e.g., the gNB 120A of the 5G NR-RAN 120).

[0028] In addition to the networks 120, 122, and 124, the network arrangement 100 further includes a cellular core network 130, the Internet 140, an IP Multimedia Subsystem (IMS) 150, and a network service backbone 160. The cellular core network 130 can be regarded as an interconnected set of components that manage the operations and traffic of the cellular network. The cellular core network 130 also manages the traffic flowing between the cellular network and the Internet 140. The IMS 150 can generally be described as an architecture for delivering multimedia services to the UE 110 using IP protocols. The IMS 150 can communicate with the cellular core network 130 and the Internet 140 to provide multimedia services to the UE 110. The network service backbone 160 communicates directly or indirectly with the Internet 140 and the cellular core network 130. The network service backbone 160 can generally be described as a set of components (e.g., servers, network storage arrangements, etc.) that implement a set of services that can be used to extend the functions for the UE 110 to communicate with various networks.

[0029] Figure 2 An exemplary UE 110 is shown according to various exemplary embodiments. The UE 110 will be described with reference to Figure 1 the network arrangement 100. The UE 110 can represent any electronic device and can include a processor 205, a memory arrangement 210, a display device 215, an input / output (I / O) device 220, a transceiver 225, and other components 230. The other components 230 can include, for example, an audio input device, an audio output device, a battery that provides limited power, a data acquisition device, a port for electrically connecting the UE 110 to other electronic devices, one or more antenna panels, etc.

[0030] The processor 205 can be configured to execute multiple engines of the UE 110. For example, the engines can include a SA PLMN database engine 235 and a SA PLMN selection engine 240. The SA PLMN database engine 235 can be configured to manage the SA PLMN database locally stored at the UE 110. This can include populating the entries within the database to indicate whether a particular cell identity supports the SA function. The SA PLMN selection engine can be configured to utilize the SA PLMN database and other techniques during the PLMN selection and reselection processes.

[0031] The above engines, each as an application (e.g., a program) executed by the processor 205, are merely exemplary. The functions associated with the engines can also be represented as stand-alone integrated components of the UE 110, or can be modular components coupled to the UE 110, e.g., an integrated circuit with or without firmware. For example, the integrated circuit can include an input circuit for receiving signals and a processing circuit for processing the signals and other information. The engines can also be embodied as one application or separate multiple applications. Additionally, in some UEs, the functionality described for the processor 205 is shared among two or more processors such as a baseband processor and an application processor. The exemplary embodiments can be implemented in any of these or other configurations of the UE.

[0032] The memory arrangement 210 can be a hardware component configured to store data related to the operations performed by the UE 110. The display device 215 can be a hardware component configured to display data to the user, while the I / O device 220 can be a hardware component that enables the user to make inputs. The display device 215 and the I / O device 220 can be separate components or can be integrated together (such as a touch screen). The transceiver 225 can be a hardware component configured to establish connections with the 5G NR-RAN 120, LTE-RAN 122, WLAN 124, etc. Thus, the transceiver 225 can operate on multiple different frequencies or channels (e.g., a set of contiguous frequencies).

[0033] Figure 3 A method 300 for maintaining a SA PLMN database is shown according to various exemplary embodiments. Method 300 will be described with reference to Figure 1 the network arrangement 100 and Figure 2 the UE 110. Method 300 provides a general overview of how the UE 110 can maintain the SA PLMN database. An example of how the UE 110 can utilize the SA PLMN database for PLMN selection will be described after the description of method 300.

[0034] In 305, the UE 110 initiates PLMN selection. Those skilled in the art will understand that PLMN selection may be initiated for any of a variety of different reasons. To provide an example, the UE 110 may perform PLMN selection in response to a power cycle of the UE 110 and / or the baseband processor, a flight mode switch, a no service (OOS) state, etc. However, the exemplary embodiments are not limited to initiating PLMN selection for any particular reason and may be applied whenever the UE 110 is triggered to perform PLMN selection or reselection.

[0035] In 310, the UE 110 scans one or more frequencies. For example, the UE 110 may tune the transceiver 225 to listen for information broadcast by cells that may be used by the UE 110 to establish a network connection.

[0036] As described above, information related to PLMN selection may be included in SIB1. Those skilled in the art will understand that the UE 110 may perform one or more synchronization operations before being able to receive SIB1. For example, when tuned to a certain frequency, the UE 110 may receive various signals in the air. If a cell is operating on the currently tuned frequency, it may broadcast various types of synchronization signals, such as the master information block (MIB), via the physical broadcast channel (PBSCH). The MIB may partially include control information that allows the UE 110 to receive other synchronization signals (such as SIB1) broadcast by the cell. Thus, scanning the one or more frequencies may at least partially include processing the signals received in the air and determining whether synchronization signals have been broadcast by the cell.

[0037] In 315, the UE 110 receives SIB1 from a 5G NR cell. For example, the UE 110 may receive SIB1 broadcast by the gNB 120A. As will be described in more detail below, the UE 110 may store an indication as to whether the 5G NR cell supports the SA function based on the content of SIB1.

[0038] In 320, the UE 110 determines whether SIB1 includes a tracking area code information element (IE). As described above, the tracking area code may indicate to the UE 110 whether the 5G NR cell supports the SA function or only the NSA function. If SIB1 includes the tracking area code IE, the method 300 continues to 325.

[0039] In 325, the UE 110 stores an indication that the 5G NR cell is suitable for PLMN selection when operating in SA mode. The SA PLMN database may include one or more PLMN identities (e.g., PLMN ID or any other suitable indication). For each PLMN identity, the database may include one or more cell identities (e.g., cell ID or any other suitable indication), and for each cell identity, the database may include an indication as to whether the cell supports SA functionality. For example, the UE 110 may fill a field in the SA PLMN database with a "1" to indicate that the cell ID associated with gNB 120A supports SA functionality (e.g., gNB 120A broadcasts a tracking area code in SIB1).

[0040] Returning to 320, if the SIB1 does not include the tracking area code IE, method 300 proceeds to 330. In 330, the UE 110 stores an indication that the 5G NR cell is not suitable for PLMN selection when operating in SA mode. For example, the UE 110 may fill a field in the SA PLMN database with a "0" to indicate that the cell ID associated with gNB 120A does not support SA functionality (e.g., gNB 120A does not broadcast a tracking area code in SIB1). However, the reference to storing a "1" or "0" is provided for illustrative purposes only, and exemplary embodiments may apply to storing any suitable indication.

[0041] Method 300 is described with reference to the UE 110 receiving SIB1 from a single cell. However, during an actual PLMN selection process, the UE 110 may receive information broadcast by multiple cells. Thus, method 300 may be performed for multiple SIB1s.

[0042] The SA PLMN database is described herein as a single database. However, in an actual configuration, the types of information stored in the SA PLMN database may be stored in multiple types of databases. Thus, the reference to the SA PLMN database may identify one or more different databases stored locally at the UE 110. Different entities may refer to these databases by different names. For example, some entities may refer to this type of database as an acquisition (ACQ) database or an APAC database. Exemplary embodiments are not limited to any particular number or type of databases, and the exemplary techniques herein may apply to any suitable type of one or more databases.

[0043] Figure 4 Method 400 for PLMN selection using an SA PLMN database is shown in accordance with various exemplary embodiments. Reference will be made to Figure 1 network arrangement 100, Figure 2 UE 110, andFigure 3 Method 400 is described with reference to method 300.

[0044] At 405, UE 110 initiates PLMN selection. This is substantially similar to 305 of method 300.

[0045] At 410, UE 110 determines that the information stored in the SA PLMN database is relevant to the current geographical location of UE 110. For example, the SA PLMN database may also include an indication of the geographical locations that can be served by a particular PLMN and / or a particular 5G NR cell. UE 110 may determine that the information stored in the SA PLMN database is relevant to the current geographical location of UE 110 based on the information stored in the SA PLMN database and the global positioning system (GPS) information (or any other suitable type of location information) of UE 110.

[0046] Although not shown in Figure 4 if UE 110 determines that the information stored in the SA PLMN database is not relevant to the current geographical location of UE 110, UE 110 may still update the SA PLMN database according to method 300. Thus, if UE 110 returns to this geographical location at a subsequent time, UE 110 will be able to utilize the SA PLMN database according to method 400.

[0047] At 415, UE 110 may use the information stored in the SA PLMN database to perform PLMN selection. For example, UE 110 may perform a scan and prioritize frequencies corresponding to 5G NR cells that UE 110 has previously determined to support SA functionality. In another example, UE 110 may omit scanning a particular frequency band or frequency range that UE 110 has determined is not associated with a cell that supports SA functionality. Thus, UE 110 may reduce the latency associated with PLMN search because UE 110 targets the frequency bands associated with 5G NR cells that UE 110 has determined to support SA functionality. Subsequently, method 400 ends.

[0048] Figure 5 Method 500 for implementing various techniques for performing PLMN selection when camped on a RAT below 5G NR is shown according to various exemplary embodiments. Method 500 will be described with reference to Figure 1 network arrangement 100 of Figure 2 UE 110 of Figure 3 and method 300 of

[0049] At 505, UE 110 camps on a 5G NR cell that supports SA functionality. At 510, UE 110 switches to a cell of a lower RAT. In this example, UE 110 switches to an LTE cell (e.g., eNB 122A). However, the exemplary embodiments will also apply to UE 110 switching to a legacy RAT (e.g., 3G, 2G, etc.) at 510.

[0050] At 515, UE 110 determines that UE 110 has camped on the lower RAT for a predetermined duration. This lower RAT may not provide the same type of network services and usage as 5G NR. Accordingly, UE 110 initiates PLMN selection to attempt to camp on a 5G NR cell that supports SA functionality so that UE 110 can return to receiving the full range of services that are normally available to UE 110 via the network connection. The predetermined duration may be based on any one of a variety of different factors, such as but not limited to the type of network services that UE 110 is configured to utilize, the type of operations that UE 110 is configured to perform, information received from the network, user input at UE 110, etc.

[0051] At 520, UE 110 may use one or more techniques to perform a PLMN search. One technique may include performing a scan using a SA PLMN database to find a suitable 5G NR cell that supports SA functionality at the current geographical location of UE 110. As indicated above with respect to method 400, this may include prioritizing 5G NR cells that UE 110 has determined to be suitable for PLMN selection at that location and / or omitting frequency bands / ranges from the scan that UE 110 has determined to be unsuitable for PLMN selection at that location. Another technique may include performing a scan based on the NR frequency priorities indicated in LTE SIB24.

[0052] At 525, UE 110 may select a 5G NR cell for camping. UE 110 may select the 5G NR cell based on any suitable selection criteria. At 530, UE 110 may perform a random access channel (RACH) procedure on the currently camped cell to register with the network that supports 5G SA functionality. Subsequently, method 500 ends.

[0053] Figure 6 Method 600 for transitioning from a currently camped LTE HPLMN to a 5G NR equivalent PLMN (ePLMN) or 5G NR equivalent home PLMN (eHPLMN) in accordance with various exemplary embodiments is shown. Method 600 will be described with reference to Figure 1 network arrangement 100, Figure 2 UE 110, and Figure 3 method 300.

[0054] Initially, consider the following exemplary scenario where UE 110 is attached to the LTE RAT of the HPLMN. UE 110 is configured with a 5G NR ePLMN and / or a 5G NR equivalent home PLMN (eHPLMN). Those skilled in the art will understand that the ePLMN is provided to UE 110 via network signaling, and the eHPLMN may be stored in the Universal Subscriber Identity Module (USIM). Thus, the difference between the eHPLMN and the ePLMN is at least partially how it is allocated to UE 110.

[0055] In this example, UE 110 is connected to the LTE RAT 122 for an extended duration. It should also be considered that during normal operation, there may be various mechanisms that cause UE 110 to switch from the currently camped RAT to 5G NR. For example, the network may trigger a handover from LTE to 5G NR. Method 600 pertains to the situation where these mechanisms do not cause UE 110 to switch to 5G NR. Thus, although able to access 5G NR SA services, UE 110 in this example is stuck camping on the LTE HPLMN all the time.

[0056] At 605, UE 110 initiates a Radio Resource Control (RRC) connection release. This allows UE 110 to initiate PLMN reselection.

[0057] At 610, UE 110 determines whether a 5G NR ePLMN is available. As described above, the 5G NR ePLMN may be provided to UE 110 via network signaling. For example, UE 110 may have previously received the 5G NR ePLMN in a Tracking Area Update Accept message, an Attach Accept message, or a Routing Area Update Accept message on a Circuit Switched (CS) RAT. If a 5G NR ePLMN is available, method 600 proceeds to 615.

[0058] In 615, the UE 110 considers the ePLMN as a higher-priority PLMN and then scans for 5G NR cells belonging to the ePLMN. The scan can be performed after the RRC connection release, then based on a user identity module (SIM) scan timer (e.g., 2 minutes, 6 minutes), and then incremented accordingly. The scan can be for system synchronization blocks (SSBs) and should not overlap with the idle mode paging duration. In some embodiments, a burst scan can be performed based on the information provided by a carrier for the frequency center and / or based on the information provided in a carrier beam for the absolute frequency. Due to the high bandwidth that the 5G network is operating on, the probability of having carriers with different frequencies in the same frequency band may be low. Therefore, the UE 110 can limit the SSB burst search to specific frequencies in the NR band for SA instead of a full-band scan. Similarly, in some embodiments, a burst scan can be performed on the frequencies indicated in the SA PLMN database.

[0059] In 620, the UE 110 determines whether the NR ePLMN is found during the scan. If the NR ePLMN is not found during the scan, the method 600 proceeds to 625, where the UE 110 moves back to the previously camped LTE HPLMN to read the idle mode paging occasion. Subsequently, the method returns to 615 to perform the search again. If the NR ePLMN is found, the method can proceed to 630, where the UE 110 can camp on the identified cell and attach to the 5G NR ePLMN.

[0060] Returning to 610, if the 5G NR ePLMN is not available, the method 600 proceeds to 635. In 635, the UE 110 scans for 5G NR cells belonging to the eHPLMN. The scan can be performed after the RRC connection release and can utilize a timer similar to the timer described in 615. Additionally, as described in 615, the scan can be for SSBs, can not overlap with the idle mode paging duration, and the UE 110 can limit the SSB burst search to specific frequencies in the NR band for SA instead of a full-band scan.

[0061] In 640, the UE 110 determines whether the NR eHPLMN is found during the scan. If the NR eHPLMN is not found during the scan, the method 600 proceeds to 645, where the UE 110 moves back to the LTE HPLMN to read the idle mode paging occasion. Subsequently, the method returns to 635 to perform the search again. If the NR eHPLMN is found, the method can proceed to 650, where the UE 110 can camp on the identified cell and attach to the 5G NR eHPLMN. Subsequently, the method 600 ends.

[0062] Figure 7 illustrates a method 700 for performing a PLMN search when a UE 110 is camped on a circuit switched (CS) RAT. Method 700 will be described with reference to Figure 1 the network arrangement 100 of Figure 2 the UE 110 of Figure 3 and the method 300 of

[0063] At 705, the UE 110 camps on a 5G NR cell and attaches to the 5G NR network. For example, the UE 110 may camp on gNB 120A and be operating in SA mode.

[0064] At 710, the UE 110 identifies an event that causes the UE 110 to release the 5G NR network connection. For example, the UE 110 may experience a power cycle, a flight mode switch, a circuit switched fallback (CSFB), etc. The above examples are provided for illustrative purposes only, and the exemplary embodiments are not limited to the UE110 releasing the 5G NR connection for any particular reason, and can be applied to any suitable scenario.

[0065] At 715, the UE 110 stores the last camped 5G NR frequency as the highest priority frequency for subsequent PLMN searches. Since the UE 110 was previously able to receive services on this NR frequency, the UE 110 may expect to camp on this frequency to receive NR services in a fast and efficient manner. This indication may be saved in the SA PLMN database and / or another part of the memory arrangement 210.

[0066] At 720, the UE 110 camps on a circuit switched (CS) RAT. For example, if the event at 710 is CSFB, the UE110 may currently be camped on a CS RAT. However, if the event at 710 is a power cycle or a flight mode switch, the UE 110 may have to search for and camp on a CS cell. Method 700 involves the UE 110 transitioning from being camped on a CS RAT to a 5G NR cell that supports SA functionality. Therefore, in this exemplary scenario, the following conditions are assumed. One assumption is that the SIM HPLMN selector with access technology (HPLMNwAcT) does not specify a 5G NR search. HPLMNwAcT contains a set of HPLMN codes with the specified RAT, which allows the UE110 to perform a target PLMN search. If HPLMNwAcT specifies a 5G NR search, the UE110 may perform a search for 5G NR before deciding to camp on a CS cell. Another assumption is that LTE is not available for camping. If LTE is available for camping, the UE 110 may camp on an LTE cell and then execute method 500 or method 600 to transition from the LTE cell to a 5GNR cell.

[0067] At 725, UE 110 enters the RRC idle state. For example, if UE 110 is switched to the CS RAT according to CSFB, the service using CSFB may have ended. Therefore, after the CS service has been used for its intended purpose, UE 110 may switch to the RRC idle state. To enter the RRC idle state, UE 110 may use the Signaling Connection Release Indication (SCRI). However, as indicated above at 710, there may be a scenario where UE 110 is pre - emplaced on the CS RAT after a power cycle or flight mode switch. In this type of scenario, UE 110 may be pre - emplaced on the CS RAT in the RRC idle state to receive services while searching for the 5G NR RAT.

[0068] At 730, UE 110 may perform a scan for 5G NR cells supporting SA functionality. This process may prioritize previously pre - emplaced NR frequencies and / or other cells from the SA PLMN database. This scan of the SSB can be a burst scan performed after RRC connection release and then executed in increments similar to the SIM scan timer mentioned in 615. Additionally, this scan may not interfere with idle mode paging activities.

[0069] At 735, UE 110 determines whether a 5G NR cell supporting SA functionality has been identified. If a cell is identified, method 700 proceeds to 740, where UE 110 pre - emplaces on the 5G NR cell supporting SA functionality. Subsequently, method 700 ends.

[0070] Returning to 735, if no cell has been identified, method 700 may proceed to 745. At 745, UE 110 may move back to the last pre - emplaced RAT to receive paging opportunities. Method 700 then returns to 730, where a scan for 5G NR cells supporting SA functionality is performed.

[0071] As described above, one aspect of the exemplary embodiments is a mechanism that does not rely on SIB1 and is configured to distinguish between 5G NR cells supporting SA functionality and 5G NR cells supporting only NSA functionality.

[0072] The exemplary embodiments relate to using the Master Information Block (MIB) to distinguish between SA cells and NSA cells. Using the MIB instead of SIB reduces latency because UE 110 does not have to wait to receive and process SIB1 to determine whether the corresponding cell supports SA or NSA. This allows devices configured for ultra - reliable low - latency communication (URLLC) use cases to meet low - latency requirements during the execution of the registration process or during cell reselection or when moving from the RRC idle state to the RRC connected state.

[0073] Figures 8a - 8b Illustrates how latency can be reduced by using the MIB to distinguish between a cell with SA capabilities and a cell with NSA capabilities when moving from the RRC idle state to the RRC connected state. Figure 8a Illustrates signaling diagram 800 in which UE 110 transitions between the RRC idle state and the RRC connected state based on SIB 1 when both a cell with SA capabilities and a cell with NSA capabilities are present.

[0074] Signaling diagram 800 includes UE 110, NSA cell 802, and SA cell 804. In this example, UE 110 is configured as a URLLC device, which means UE 110 is configured to operate in the SA mode.

[0075] At 805, UE 110 is operating in the RRC idle state. When in the RRC idle state, UE 110 tunes transceiver 225 to various frequencies to listen for information transmitted by cells near UE 110.

[0076] At 810, UE 110 receives the MIB from NSA cell 802 via the Physical Broadcast Channel (PBCH). At 815, UE 110 collects measurement data corresponding to NSA cell 802. At 820, UE 110 determines based on the measurement data that NSA cell 802 is suitable for preemption. At this time, UE 110 does not know that NSA cell 802 is an NSA cell.

[0077] At 825, UE 110 receives SIB1 from NSA cell 802. At 830, UE 110 determines that NSA cell 802 only supports NSA functionality. As described above, UE 110 can make this determination based on the absence of a Tracking Area Code in SIB1. Since UE 110 is operating in the SA mode, NSA cell 802 is not used for RRC connection. Therefore, UE 110 remains in the RRC idle state and continues to search for a cell with SA capabilities.

[0078] At 835, UE 110 receives the MIB from SA cell 804 via the Physical Broadcast Channel (PBCH). At 840, UE 110 collects measurement data corresponding to SA cell 804. At 845, UE 110 determines based on the measurement data that SA cell 804 is suitable for preemption. At this time, UE 110 does not know that SA cell 804 is an SA cell. At 850, UE 110 receives SIB1 from SA cell 804. At 855, UE 110 determines that SA cell 804 supports SA functionality. At 860, UE 110 establishes an RRC connection with SA cell 840.

[0079] Figure 8b FIG. 865 is a signaling diagram showing the transition of UE 110 from RRC idle state to RRC connected state based on the MIB when both a cell with SA capability and a cell with NSA capability exist.

[0080] Similar to signaling diagram 800, signaling diagram 865 includes UE 110, NSA cell 802, and SA cell 804. In this example, UE 110 is configured as a URLLC device, which means UE 110 is configured to operate in SA mode.

[0081] At 870, UE 110 is operating in the RRC idle state. When in the RRC idle state, UE 110 tunes the transceiver to various frequencies to listen for information transmitted by cells near UE 110.

[0082] At 875, UE 110 receives the MIB from NSA cell 802 via PBCH. However, in this example, the MIB is configured to indicate whether the cell supports SA functionality. In some embodiments, the MIB spare bit is configured to include an indication of whether the cell has SA capability or NSA capability. In other embodiments, the intra-frequency reselection bit is configured to indicate that cell reselection is not allowed when the cell transmitting the MIB is an NSA cell. The above examples are provided for illustrative purposes only and can be applied to the MIB, including any suitable indication of whether the cell has SA capability or NSA capability.

[0083] At 880, UE 110 ignores NSA cell 804 based on the received MIB. Comparison with signaling diagram 800 shows that UE 110 in this example is able to determine that NSA cell 802 has NSA capability and avoid the latency associated with collecting measurement data, receiving SIB1, and processing SIB1.

[0084] At 885, UE 110 receives the MIB from SA cell 804 via PBCH. Since the MIB in this example is configured to include an indication that the cell has SA capability, UE 110 can more quickly determine that SA cell 804 is suitable for URLLC operation. At 890, UE 110 collects measurement data corresponding to SA cell 804. In this example, the measurement data indicates that SA cell 804 is suitable for preemption. At 895, UE 110 establishes an RRC connection with SA cell 804.

[0085] Utilizing the MIB in the above manner can also provide benefits on the network side. For example, under normal circumstances, a UE operating in NSA mode can be configured to measure both cells with SA capabilities and cells with NSA capabilities. However, the measurement report may not contain any differentiating features other than the physical cell ID (PCI). Since SA and NSA cells may have the same PCI, this makes it more difficult for the network to perform operations related to resource tracking and resource maintenance. By utilizing the MIB to distinguish between SA and NSA cells, UE 110 can be capable of including only NSA cells in the measurement report.

[0086] Figure 9 A signaling diagram 900 for generating a measurement report that does not include SA cells is shown. The signaling diagram 900 includes UE 110, NSA cell 902, and SA cell 904. In this example, UE 110 is operating in NSA mode, and thus, UE 110 does not have to include cells with SA capabilities in the measurement report.

[0087] In 905, UE 110 receives the MIB from NSA cell 902 via PBCH. Similar to the signaling diagram 850, the MIB is configured to indicate whether the cell has SA capabilities or NSA capabilities. In 910, UE 110 collects measurement data corresponding to NSA cell 902. Since UE 110 is able to determine that NSA cell 902 supports NSA functionality, UE 110 collects the measurement data for the measurement report to be provided to the network.

[0088] In 915, UE 110 receives the MIB from SA cell 904 via PBCH. In 920, UE 110 ignores SA cell 904. Since UE 110 is operating in NSA mode and SA cell 904 provides SA functionality, UE 110 does not have to include SA cell 904 in the measurement report. In 925, UE 110 provides the measurement report to NSA cell 902. Utilizing the MIB in this manner can also reduce the latency during PLMN search, because UE 110 does not need to receive and process SIB1 to determine whether the corresponding cell supports SA functionality or NSA functionality.

[0089] Those skilled in the art will understand that the above-described exemplary embodiments can be implemented with any suitable software configuration or hardware configuration or a combination thereof. Exemplary hardware platforms for implementing the exemplary embodiments may include, for example, Intel x86-based platforms with compatible operating systems, Windows OS, Mac platforms and MAC OS, mobile devices with operating systems such as iOS, Android, etc. In other examples, the exemplary embodiments of the above methods may be embodied as a program including lines of code stored on a non-transitory computer-readable storage medium, which, when compiled, can be executed on a processor or microprocessor.

[0090] Although this patent application describes various combinations of various embodiments each having different features, those skilled in the art will understand that any feature of one embodiment can be combined with the features of other embodiments in any manner not negated by the disclosure or features that are not functionally or logically inconsistent with the operation of the devices of the embodiments disclosed in the present invention or the said functions.

[0091] It is well known that the use of personally identifiable information should follow privacy policies and practices that are recognized as meeting or exceeding industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of inadvertent or unauthorized access or use, and the nature of the authorized use should be clearly explained to the user.

[0092] It will be apparent to those skilled in the art that various modifications can be made to the present disclosure without departing from the essence or scope of the present disclosure. Accordingly, the present disclosure is intended to cover modifications and variations of the present disclosure, provided that these modifications and variations are within the scope of the appended claims and their equivalents.

Claims

1. A computer-readable storage medium, the computer-readable storage medium comprising a set of instructions, wherein the set of instructions, when executed by a processor of a user equipment (UE), causes the processor to perform operations, including: Receiving a signal broadcast by a cell of a New Radio (NR) network; Determining, based on the received signal, whether the cell is configured for Standalone (SA) operation of NR; When the cell is configured for the SA operation of NR, locally storing, at the UE, a first indication that the cell is configured for the SA operation of NR; When the cell is not configured for the SA operation of NR, locally storing, at the UE, a second indication that the cell is configured for Non-Standalone (NSA) operation of NR; And Initiating a Public Land Mobile Network (PLMN) search process, wherein the PLMN search process includes a frequency scan based on the first indication or the second indication, and wherein the PLMN search process preferentially processes a previously pre-empted NR cell determined to support SA operation.

2. The computer-readable storage medium according to claim 1, wherein the signal is System Information Block 1 (SIB1).

3. The computer-readable storage medium according to claim 1, wherein the signal is a Master Information Block (MIB), and determining whether the cell is configured for the SA operation of NR is based on spare bits included in the MIB or frequency reselection bits included in the MIB.

4. The computer-readable storage medium according to claim 1, wherein the frequency scan targets a frequency or a frequency range associated with the cell based on the first indication.

5. The computer-readable storage medium according to claim 1, wherein the frequency scan does not scan one or more frequencies or frequency ranges based on the second indication.

6. The computer-readable storage medium according to claim 1, the instructions further comprising: Pre-empting on a previously pre-empted Radio Access Technology (RAT) to monitor a paging occasion.

7. The computer-readable storage medium according to claim 1, the instructions further comprising: Determining whether an equivalent PLMN (ePLMN) is available.

8. The computer-readable storage medium according to claim 7, when the ePLMN is available, the frequency scan targets cells of the ePLMN.

9. The computer-readable storage medium according to claim 7, when the ePLMN is not available, the frequency scan targets cells of an equivalent Home PLMN (eHPLMN).

10. A user equipment (UE), comprising: A transceiver configured to communicate with one or more networks; And A processor configured to perform operations, the operations including: Receiving a signal broadcast by a cell of a New Radio (NR) network; Decoding the signal to determine whether the cell is configured for Standalone (SA) operation of NR; When the cell is configured for the Standalone (SA) operation of NR, locally store, at the UE, a first indication that the cell is configured for the SA operation of NR; When the cell is not configured for the SA operation of NR, locally store, at the UE, a second indication that the cell is configured for the Non-Standalone (NSA) operation of NR; and Initiate a Public Land Mobile Network (PLMN) search procedure, wherein the PLMN search procedure includes a frequency scan based on the first indication or the second indication, and wherein the PLMN search procedure preferentially processes a previously pre-empted NR cell determined to support the SA operation.

11. The UE according to claim 10, wherein the signal is System Information Block 1 (SIB1).

12. The UE according to claim 10, wherein the signal is the Master Information Block (MIB).

13. The UE according to claim 12, wherein determining whether the cell is configured for the SA operation of NR is based on spare bits included in the MIB or intra-frequency reselection bits included in the MIB.

14. The UE according to claim 10, wherein the frequency scan targets a frequency associated with the cell based on the first indication.

15. The UE according to claim 10, wherein the frequency scan does not scan one or more frequencies based on the second indication.

16. The UE according to claim 10, the operation further comprising: Pre-empt on a previously pre-empted Radio Access Technology (RAT) to monitor a paging occasion.

17. An integrated circuit, comprising: A circuit configured to receive a signal broadcast by a cell of a New Radio (NR) network; A circuit configured to decode the signal to determine whether the cell is configured for the Standalone (SA) operation of NR; A circuit configured to locally store, at the UE, a first indication that the cell is configured for the SA operation of NR when the cell is configured for the SA operation of NR; A circuit configured to locally store, at the UE, a second indication that the cell is configured for the Non-Standalone (NSA) operation of NR when the cell is not configured for the SA operation of NR; And A circuit configured to initiate a Public Land Mobile Network (PLMN) search procedure, wherein the PLMN search procedure includes a frequency scan based on the first indication or the second indication, and wherein the PLMN search procedure preferentially processes a previously pre-empted NR cell determined to support the SA operation.

18. The integrated circuit according to claim 17, wherein the signal is the Master Information Block (MIB), and wherein determining whether the cell is configured for the SA operation of NR is based on spare bits included in the MIB or intra-frequency reselection bits included in the MIB.

19. The integrated circuit according to claim 17, wherein the frequency scan targets a frequency or a frequency range associated with the cell based on the first indication.

20. The integrated circuit according to claim 17, wherein the frequency scanning does not scan one or more frequencies or frequency ranges based on the second indication.

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