Patent Description:
A communication protocol defined by the 3GPP, referred to as EN-DC (Evolved Universal Terrestrial Radio Access Network (E-UTRAN)/New Radio-Dual Connectivity) enables the simultaneous use of LTE and NR radio access technologies for communications between a mobile device and a cellular communication network. EN-DC may also be referred to as LTE/NR dual connectivity. EN-DC is described by 3GPP Technical Specification (TS) <NUM>.

EN-DC can be implemented in conjunction with a <NUM> core network, with the support of <NUM> base stations, in a configuration known as Non-Standalone Architecture (NSA). In this configuration, a <NUM> LTE base station (referred to as a Master eNodeB or MeNB) is associated (e.g., via an X2 interface) with a <NUM> NR base station (referred to as a Secondary gNodeB or SgNB). In an NSA system, both the LTE base station and the NR base station support a <NUM> core network. However, control communications are between the <NUM> core network and the LTE base station, and the LTE base station is configured to communicate with and to control the NR base station. The relevant prior art includes <CIT> and <NPL>.

There is provided a method and a system as defined in the claims.

The systems, devices, and techniques described herein relate to handover of communication sessions between Non-Standalone (NSA) and Standalone (SA) networks. In various implementations, handover of a communication session between a User Equipment (UE) and a particular network architecture can be triggered based on radio conditions experienced by the UE.

In some implementations, a communication session provided to a UE over a dual radio bearer provided by a first base station in an NSA network can be handed over to a single radio bearer provided by a second base station in an SA network. For instance, upon receiving a report that a power or quality of a radio signal over the single radio bearer exceeds a particular threshold and/or that a power or quality of a radio signal over the dual radio bearer is below a certain threshold, the first base station may cause a first core network associated with the NSA network to hand over the communication session to a second core network associated with the SA network. In response to receiving a message indicating that the communication session has been handed over to the second core network, the first base station may cause the communication session to be handed over from the dual radio bearer to the single radio bearer provided by the second base station. The first base station may also sever the dual radio bearer between the first base station and the UE.

In various examples, a communication session provided to a UE over a single radio bearer provided by a third base station in an SA network can be handed over to a dual radio bearer provided by a fourth base station in an NSA network. For instance, upon receiving a report that a power or quality of a radio signal received by the UE is below a particular threshold, the third base station may cause a third core network associated with the SA network to hand over the communication session to a fourth core network associated with the NSA network. In response to receiving a message indicating that the communication session has been handed over to the fourth core network, the third base station may cause the communication session to be handed over from the single radio bearer to the dual radio bearer provided by the fourth base station. The third base station may also sever the single radio bearer between the third base station and the UE.

According to various examples, a single radio bearer may be a <NUM> (e.g., NR) radio bearer. The dual radio bearer may include a <NUM> radio bearer and a <NUM> (e.g., LTE) radio bearer. In some cases, the single <NUM> radio bearer may utilize higher frequency radio spectrum than the <NUM> radio bearer in the dual radio bearer. Higher frequency radio signals may experience higher attenuation than lower frequency radio signals. Accordingly, a coverage area of the single <NUM> radio bearer may be smaller than a coverage area of the <NUM> radio bearer. Due to the inclusion of the <NUM> radio bearer, the dual radio bearer may be configured to provide services wirelessly to UEs located in a broader area than the single <NUM> radio bearer.

However, in some cases, the <NUM> radio bearer may be provided using limited resources. For instance, the <NUM> radio bearer may be associated with one or more channels in a limited amount of <NUM> radio resources (e.g., frequency spectrum). Thus, it may be advantageous to avoid the use of the <NUM> radio bearer in order to conserve the <NUM> radio resources.

In some cases, a base station managing handover (e.g., the first base station or the third base station) may also forward context data related to the communication session to the next base station (e.g., the second base station or the fourth base station). For example, the base station managing handover may be receiving data in the communication session during the handover process. When the managing base station hands over the communication session to the next base station, the managing base station may also transmit the data received during the handover process to the next base station.

Various implementations of this disclosure relate to managing physical radio bearers based on measurements of radio conditions. Accordingly, example implementations can apply to practical applications in real-world environments.

In addition, various implementations provide specific improvements to the field of telecommunications. For instance, selective handover of a UE between SA and NSA radio bearers may enable a RAN to conserve LTE radio resources while still maintaining a high transfer rate and quality of data received by the UE.

<FIG> illustrates an example environment <NUM> for handover between Non-Standalone (NSA) and Standalone (SA) network environments. As used herein the terms "Non-Standalone," "Nonstandalone," "NSA," and their equivalents can refer to a telecommunications network architecture that can utilize multiple Radio Access Technologies (RATs) to deliver services to end UEs. In some cases of NSA architectures, 5th Generation (<NUM>) services can be provided to users using existing 4th Generation (<NUM>) architecture.

The NSA network environment may include a dual bearer Radio Access Network (RAN) <NUM> associated with a dual bearer coverage area <NUM>. As used herein, the term "RAN" and its equivalents may refer to a network including at least one of a 3GPP RAN, such a GSM/EDGE RAN (GERAN), a Universal Terrestrial RAN (UTRAN), or an Evolved UTRAN (E-UTRAN), a <NUM> UTRAN, or alternatively, via a "non-3GPP" RAN, such as a Wi-Fi RAN, or another type of wireless local area network (WLAN) that is based on the IEEE <NUM> standards. In some instances, a RAN can include a Wi-Fi Access Point (AP). In some cases, a RAN can include an eNodeB, a gNodeB, or a combination thereof. For instance, the dual bearer RAN <NUM> may include an eNodeB (configured to wirelessly transmit and/or receive signals over one or more Long Term Evolution (LTE) bands) and a gNodeB (configured to wirelessly transmit and/or receive signals over one or more New Radio (NR) bands).

In various examples, the dual bearer RAN <NUM> may be connected to a <NUM> core network (e.g., an Evolved Packet Core (EPC)) (not illustrated) and is associated with Option <NUM>, Option 3A, Option 3X, or the like. In examples referred to as "Option <NUM>," user plane data may be transmitted between an end UE and the <NUM> RAN, between the end UE and the <NUM> RAN, between the <NUM> RAN and the <NUM> RAN, and between the <NUM> RAN and the <NUM> core network. In Option <NUM>, control plane data may be transmitted between the end UE and the <NUM> RAN, between the <NUM> RAN and the <NUM> RAN, and between the <NUM> RAN and the <NUM> core network. In various implementations of Option <NUM>, both user plane data and control plane data may be transferred through the <NUM> RAN.

In examples referred to as "Option 3A," user plane data may be transmitted between an end UE and the <NUM> RAN, between the end UE and the <NUM> RAN, between the <NUM> RAN and the <NUM> core network, and between the <NUM> RAN and the <NUM> core network. In Option 3A, control plane data may be transmitted between the end UE and the <NUM> RAN, between the <NUM> RAN and the <NUM> RAN, and between the <NUM> RAN and the <NUM> core network. In various instances of Option 3A, user plane data may be transferred through the <NUM> RAN and/or the <NUM> RAN, and control plane data may be transferred through the <NUM> RAN.

In examples referred to as "Option 3X," user plane data can be transmitted between the <NUM> RAN and the end UE via a <NUM> radio bearer, between the <NUM> RAN and the <NUM> RAN, and between the <NUM> RAN and the <NUM> core network. In addition, in Option 3X, control plane data may be transmitted between the <NUM> RAN and the UE, between the <NUM> RAN and the <NUM> RAN, and between the <NUM> RAN and the <NUM> core network. Accordingly, in Option 3X, user plane data may be transferred through the <NUM> RAN and control plane data may be transferred through the <NUM> RAN. Examples in which the dual bearer RAN <NUM> is associated with Option 3X will be described in further detail below with respect to <FIG>.

NSA architectures, such as architectures including the dual bearer RAN <NUM>, can support dual connectivity. As used herein, the terms "dual connection," "dual bearer," or the like can refer to a radio bearer simultaneously utilizing at least two types of RATs. For instance, a dual bearer may include a <NUM> radio bearer and a <NUM> radio bearer. According to some examples, user plane data may be transmitted between a <NUM> core network and an end UE simultaneously via a <NUM> RAN and a <NUM> RAN in various NSA deployments.

The SA network environment illustrated in <FIG> may include a single bearer RAN <NUM> associated with a single bearer coverage area <NUM>. As used herein, the terms "Standalone," "SA," and their equivalents can refer to a telecommunications architecture in which a core network can utilize a single RAT to deliver services to end UEs. For instance, in examples of an "Option <NUM>" deployment, user plane data and control plane data between a <NUM> core network and an end UE may be transferred through a <NUM> RAN. In examples of an "Option <NUM>" deployment, user plane data and control plane data between a <NUM> core network (e.g., a <NUM> Core (5GC)) and an end UE may be transferred through a <NUM> RAN. In some examples of an "Option <NUM>" deployment, user plane data and control plane data between a <NUM> core network and an end UE may be transferred through a <NUM> RAN.

A User Equipment (UE) <NUM> may move throughout the dual bearer coverage area <NUM> and/or the single bearer coverage area <NUM>. As used herein, the terms "UE," "user device," "wireless communication device," "wireless device," "communication device," "mobile device," "client device," and "terminal" can be used interchangeably herein to describe any UE (e.g., the first UE <NUM>) that is capable of transmitting/receiving data wirelessly using any suitable wireless communications/data technology, protocol, or standard, such as Global System for Mobile Communications (GSM), Time Division Multiple Access (TDMA), Universal Mobile Telecommunications System (UMTS), Evolution-Data Optimized (EVDO), Long Term Evolution (LTE), Advanced LTE (LTE+), New Radio (NR), Generic Access Network (GAN), Unlicensed Mobile Access (UMA), Code Division Multiple Access (CDMA), Orthogonal Frequency Division Multiple Access (OFDM), General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Advanced Mobile Phone System (AMPS), High Speed Packet Access (HSPA), evolved HSPA (HSPA+), Voice over Internet Protocol (IP) (VoIP), VoLTE, Institute of Electrical and Electronics Engineers' (IEEE) <NUM>. 1x protocols, WiMAX, Wi-Fi, Data Over Cable Service Interface Specification (DOCSIS), digital subscriber line (DSL), and/or any future IP-based network technology or evolution of an existing IP-based network technology.

In general, the UE <NUM> can be implemented as any suitable type of computing device configured to communicate over a wired or wireless network, including, without limitation, a mobile phone (e.g., a smart phone), a tablet computer, a laptop computer, a Portable Digital Assistant (PDA), a wearable computer (e.g., electronic/smart glasses, a smart watch, fitness trackers, etc.), an Internet-of-Things (IoT) device, an in-vehicle (e.g., in-car) computer, and/or any similar mobile device, as well as situated computing devices including, without limitation, a television (smart television), a Set-Top-Box (STB), a desktop computer, and the like.

When the UE <NUM> is located in the dual bearer coverage area <NUM>, the UE <NUM> may be configured to transmit and/or receive data over a dual <NUM>/<NUM> bearer <NUM> provided by the dual bearer RAN <NUM>. The dual <NUM>/<NUM> bearer <NUM> may include at least two radio bearers: one <NUM> (e.g., LTE) radio bearer and one <NUM> (e.g., NR) radio bearer. As used herein, the terms "radio bearer," "radio link," "radio channel," or their equivalents, can refer to one or more radio resources over which data can be transmitted wirelessly between at least two nodes in a network. According to various cases, a radio bearer may be defined according to one or more frequency bands, one or more time intervals, or a combination thereof. In some examples, a radio bearer carrying user plane data may be referred to as a "Data Radio Bearer (DRB). " For instance, services (e.g., voice services) may be transmitted over one or more DRBs. A radio bearer carrying control plane data may be referred to as a "Signaling Radio Bearer (SRB). " For instance, Radio Resource Control (RRC) messages and Non-Access Stratum (NAS) signals may be transmitted over one or more SRBs.

As used herein, the term "<NUM> radio bearer" and its equivalents can refer to a radio bearer utilizing one or more <NUM>-specific radio resources and/or a <NUM>-specific signaling protocol. For instance, in various implementations, at least one of NR bands n71, n260, and/or n261 may be specifically allocated to <NUM> radio signaling. In some cases, <NUM>-specific radio resources may include millimeter wave radio resources, such as resources within n260 and/or n261.

As used herein, the term "<NUM> radio bearer" and its equivalents can refer to a radio bearer utilizing one or more <NUM> radio resources and/or a <NUM> signaling protocol. In some cases, at least one of LTE bands <NUM>, <NUM>, <NUM>, or <NUM> may be allocated to <NUM> radio signaling.

When the UE <NUM> is located in the single bearer coverage area <NUM>, the UE <NUM> may be configured to transmit and/or receive data over a single <NUM> bearer <NUM> provided by the single bearer RAN <NUM>. In various implementations, the single <NUM> bearer <NUM> may be a <NUM> radio bearer.

In various implementations, the UE <NUM> may move between a Position A <NUM> and a Position B <NUM> while being engaged in an ongoing communication session. In some cases, the communication session may be handed over between the NSA network environment (e.g., including the dual bearer RAN <NUM>) and the SA network environment (e.g., including the single bearer RAN <NUM>).

In various instances, the UE <NUM> may be located at Position A and may be utilizing the NSA network architecture. The UE <NUM> may be transmitting and/or receiving data wirelessly with the dual bearer RAN <NUM> over the dual <NUM>/<NUM> bearer <NUM>. The data may be at least part of the existing communication session.

The dual bearer RAN <NUM> may transmit at least one message indicating one or more radio thresholds. For instance, the dual bearer RAN <NUM> may transmit an RRC configuration message that indicates a first threshold that can be compared to a signal received from the single bearer RAN <NUM>. In some cases, the RRC reconfiguration message may further indicate a second threshold that can be compared to a signal received from the dual bearer RAN <NUM>. For example, the RRC reconfiguration message may specify at least one B2 event.

In example instances, the dual bearer RAN <NUM> may transmit, to the UE <NUM>, a first RRC reconfiguration message indicating the first threshold and a second RRC reconfiguration message indicating the second threshold. In some examples, at least one of the first threshold or the second threshold may include a power threshold, such as a Received Signal Strength Indicator (RSSI), a Reference Signal Received Power (RSRP), or the like. In some cases, at least one of the first threshold or the second threshold may include a signal quality threshold, such as a Reference Signal Received Quality (RSRQ), a Signal to Interference plus Noise Ratio (SINR), or the like.

The RRC reconfiguration message(s) transmitted by the dual bearer RAN <NUM> to the UE <NUM> may further identify the signal from the single bearer RAN <NUM> that can be compared to the first threshold and/or the signal from the dual bearer RAN <NUM> that can be compared to the second threshold. For instance, the RRC configuration message(s) may identify the type of signal by at least one of a channel, a frequency, a band, a slot, a subframe, or the like, in which the signal to be measured will be transmitted. In various implementations, the signal to be compared to the first threshold is transmitted by the single bearer RAN <NUM> in a <NUM>-specific band (e.g., a millimeter wave band, n71, n260 and/or n261). In some cases, the signal to be compared to the second threshold is transmitted by the dual bearer RAN <NUM> in a <NUM>-specific band (LTE bands <NUM>, <NUM>, and/or <NUM>) and/or a shared <NUM>/<NUM> band (e.g., LTE band <NUM> and NR band n71).

The UE <NUM> may receive wireless signals from the single bearer RAN <NUM> and compare the wireless signals to the first threshold. In various examples, the UE <NUM> may receive wireless signals from the dual bearer RAN <NUM> and compare the wireless signals to the second threshold. If the UE <NUM> determines that the signals from the single bearer RAN <NUM> are above the first threshold and/or that the signals from the dual bearer RAN <NUM> are below the second threshold, the UE <NUM> may transmit a report to the dual bearer RAN <NUM>. For instance, the UE <NUM> may move from Position A <NUM> to Position B <NUM>, thereby moving to a cell edge of the dual bearer coverage area <NUM> and entering the single bearer coverage area <NUM>.

Upon receiving the report from the UE <NUM>, the dual bearer RAN <NUM> may cause the communication session to be handed over from the dual bearer RAN <NUM> to the single bearer RAN <NUM>. In some cases, the dual bearer RAN <NUM> may request a first core network associated with the dual bearer RAN <NUM> (e.g., an EPC) to hand over the communication session to a second core network associated with the single bearer RAN <NUM> (e.g., a 5GC). The first core network may request the second core network to transfer the communication session. When the second core network has confirmed, to the first core network, that the communication session has been transferred, the first core network may report, to the dual bearer RAN <NUM>, that the communication session has been handed over to the second core network.

In response to identifying that the communication session has been handed over to the second core network, the dual bearer RAN <NUM> may initiate handover of the communication session to the single bearer RAN <NUM>. In various examples, the dual bearer RAN <NUM> may transmit, to the UE <NUM>, an instruction to connect to the single bearer RAN <NUM>. The instruction may be, for instance, in an RRC reconfiguration message.

When the UE <NUM> receives the instruction from the dual bearer RAN <NUM>, the UE <NUM> may establish a connection with the single bearer RAN <NUM>. For instance, the UE <NUM> and the single bearer RAN <NUM> may exchange Session Initiation Protocol (SIP) messages and/or may synchronize. The UE <NUM> may attach to the single bearer RAN <NUM>. Because the communication session has already been transferred to the second core network associated with the single bearer RAN <NUM>, the UE <NUM> may be enabled to immediately transmit and/or receive data in the communication session via the single <NUM> bearer <NUM> provided by the single bearer RAN <NUM>.

In various cases, the process of transferring the session from the first core network to the second core network may take a non-negligible amount of time. Further, the process of transferring the session from the dual bearer RAN <NUM> to the single bearer RAN <NUM> may also take a non-negligible amount of time. During these latency periods, the dual bearer RAN <NUM> may continue receiving data in the communication session. This data may be referred to as a "session context," "context data," or their equivalent terminology. To ensure that the session context is retained during handover from the NSA network architecture to the SA network architecture, the dual bearer RAN <NUM> may further cause the session context to be transmitted to the single bearer RAN <NUM>. For instance, the dual bearer RAN <NUM> may transmit the session context to the first core network, which may transfer the session context to the second core network, which may deliver the second context to the single bearer RAN <NUM>.

In some implementations, the dual bearer RAN <NUM> may also end the dual <NUM>/<NUM> bearer <NUM>. For example, the dual bearer RAN <NUM> may sever the dual <NUM>/<NUM> bearer <NUM> in response to transmitting the instruction to the UE <NUM> to transfer the session to the single bearer RAN <NUM>.

In various implementations, the communication session may be handed over from the single bearer RAN <NUM> to the dual bearer RAN <NUM>. For instance, the UE <NUM> may be transmitting and/or receiving data via a the single <NUM> bearer <NUM>. The data may be part of the communication session.

The single bearer RAN <NUM> may transmit a message indicating a radio threshold. For instance, the single bearer RAN <NUM> may transmit an RRC reconfiguration message that indicates a third threshold that can be compared to a signal received from the dual bearer RAN <NUM>. For example, the RRC reconfiguration message may specify an A4 event.

In example instances, the third threshold may include a power threshold, such as an RSSI, an RSRP, or the like. In some cases, the third threshold may include a signal quality threshold, such as an RSRQ, a SINR, or the like. According to some implementations, the third threshold may be the same as the first threshold.

The RRC reconfiguration message transmitted by the single bearer RAN <NUM> to the UE <NUM> may further identify the signal from the dual bearer RAN <NUM> that can be compared to the third threshold. For instance, the RRC reconfiguration message(s) may identify the type of signal by at least one of a channel, a frequency, a band, a slot, a subframe, or the like, in which the signal to be measured will be transmitted. In some cases, the signal to be compared to the third threshold is transmitted by the dual bearer RAN <NUM> in a <NUM>-specific band (LTE bands <NUM>, <NUM>, and/or <NUM>) and/or a shared <NUM>/<NUM> band (e.g., LTE band <NUM>/n71).

The UE <NUM> may receive wireless signals from the dual bearer RAN <NUM> and compare the wireless signals to the third threshold. If the UE <NUM> determines that the signals from the dual bearer RAN <NUM> are above the third threshold, the UE <NUM> may transmit a report to the single bearer RAN <NUM>. For instance, the UE <NUM> may move from Position B <NUM> to Position A <NUM>, thereby leaving the single bearer coverage area <NUM> and entering a mid-cell region of the dual bearer coverage area <NUM>.

Upon receiving the report from the UE <NUM>, the single bearer RAN <NUM> may cause the communication session to be handed over from the single bearer RAN <NUM> to the dual bearer RAN <NUM>. In some cases, the single bearer RAN <NUM> may request the second core network associated with the single bearer RAN <NUM> (e.g., a 5GC) to hand over the communication session to the first core network associated with the dual bearer RAN <NUM> (e.g., an EPC). The second core network may request the first core network to transfer the communication session. When the first core network has confirmed, to the second core network, that the communication session has been transferred, the second core network may report, to the single bearer RAN <NUM>, that the communication session has been handed over to the first core network.

In response to identifying that the communication session has been handed over to the first core network, the single bearer RAN <NUM> may initiate handover of the communication session to the dual bearer RAN <NUM>. In various examples, the single bearer RAN <NUM> may transmit, to the UE <NUM>, an instruction to connect to the dual bearer RAN <NUM>. The instruction may be, for instance, in an RRC reconfiguration message.

When the UE <NUM> receives the instruction from the single bearer RAN <NUM>, the UE <NUM> may establish a connection with the dual bearer RAN <NUM>. For instance, the UE <NUM> and the single bearer RAN <NUM> may exchange SIP messages and/or may synchronize. The UE <NUM> may attach to the dual bearer RAN <NUM>. Because the communication session has already been transferred to the first core network associated with the dual bearer RAN <NUM>, the UE <NUM> may be enabled to immediately transmit and/or receive data in the communication session via the dual <NUM>/<NUM> bearer <NUM> provided by the dual bearer RAN <NUM>.

In various cases, the process of transferring the session from the second core network to the first core network may take a non-negligible amount of time. Further, the process of transferring the session from the single bearer RAN <NUM> to the dual bearer RAN <NUM> may also take a non-negligible amount of time. During these latency periods, the single bearer RAN <NUM> may continue receiving session context data. To ensure that the session context is not lost during handover from the SA network to the NSA network, the single bearer RAN <NUM> may further cause the session context to be transmitted to the dual bearer RAN <NUM>. For instance, the single bearer RAN <NUM> may transmit the session context to the second core network, which may transfer the session context to the first core network, which may deliver the second context to the dual bearer RAN <NUM>.

In some implementations, the single bearer RAN <NUM> may also end the single <NUM> bearer <NUM> used to communicate with the UE <NUM>. For example, the single bearer RAN <NUM> may sever the single <NUM> bearer <NUM> in response to transmitting the instruction to the UE <NUM> to transfer the session to the dual bearer RAN <NUM>.

Although not illustrated in <FIG>, in some cases, the dual bearer RAN <NUM> and the single bearer RAN <NUM> may be collocated on the same base station. Accordingly, in some cases, the single bearer coverage area <NUM> may be substantially contained within the dual bearer coverage area <NUM>.

<FIG> illustrates an example environment <NUM> illustrating interfaces and various elements of a Non-Standalone (NSA) network architecture and a Standalone (SA) network architecture. The example environment <NUM> illustrated in <FIG> includes some constituents of the example environment <NUM> described above with reference to <FIG>. For instance, the example environment <NUM> includes the dual bearer Radio Access Network (RAN) <NUM>, the single bearer RAN <NUM>, the User Equipment (UE) <NUM>, the single <NUM> bearer <NUM>, Position A <NUM>, and Position B <NUM>, described above with reference to <FIG>.

In the examples illustrated in <FIG>, the dual bearer RAN <NUM> may include a master RAN <NUM> and a secondary RAN <NUM>. As used herein, the term "master RAN" may refer to a RAN that can communicate wirelessly with at least one UE and can manages and/or controls wireless communications of at least one secondary RAN with the UE(s). As used herein, the term "secondary RAN" may refer to a RAN that can communicate wirelessly with one or more UEs according to control plane data received from a master RAN. For instance, as illustrated in <FIG>, the master RAN <NUM> can control the secondary RAN <NUM>.

A <NUM> split bearer <NUM> and a <NUM> split bearer <NUM>, collectively, may be a dual <NUM>/<NUM> bearer (such as the dual <NUM>/<NUM> bearer <NUM> described above with reference to <FIG>). The master RAN <NUM> may be configured to transmit and/or receive data with the UE <NUM> over the <NUM> split bearer <NUM>. The <NUM> split bearer <NUM> may be a Master Cell Group (MCG) bearer. As used herein, the term "MCG bearer" can refer to a radio bearer that is served only by a master RAN. The secondary RAN <NUM> may be configured to transmit and/or receive data with the UE <NUM> over the <NUM> split bearer <NUM>. The <NUM> split bearer <NUM> may be a Secondary Cell Group (SCG) bearer. As used herein, the term "SCG bearer" can refer to a radio bearer that is served only by a secondary RAN.

The master RAN <NUM> and the secondary RAN <NUM> may be connected to each other over an X2 interface, which may be a backhaul link between the master RAN <NUM> and the secondary RAN <NUM>. In various implementations, the secondary RAN <NUM> may forward user plane data between the master RAN <NUM> and the UE <NUM> over the X2 interface. As used herein, the term "user plane data" may refer to data included in user traffic transmitted throughout one or more networks. For instance, in a voice call in which voice services are transmitted between two nodes in a network, user plane data may include data comprising the voice services.

In some cases, the master RAN <NUM> may control the secondary RAN <NUM> by exchanging control plane data with the secondary RAN <NUM> over the X2 interface. As used herein, the term "control plane data" may refer to data included in signaling traffic transmitted throughout one or more networks. For instance, control plane data may include RRC messages, control messages, or the like, transmitted between two nodes in a network.

The master RAN <NUM> may be connected to a <NUM> core network <NUM> via at least one S1 interface. In some examples, the <NUM> core network <NUM> may include an Evolved Packet Core (EPC). In certain instances, various components of the EPC can include, but are not limited to, a Mobility Management Entity (MME), a Serving Gateway (SGW), a Packet Data Network (PDN) Gateway (PGW), a Home Subscriber Server (HSS), an Access Network Discovery and Selection Function (ANDSF), and/or an evolved Packet Data Gateway (ePDG). An SGW can include a component that handles user-plane data (SGW-U) and a component that handles control-plane data (SGW-C). A PDN can include a component that handles user-plane data (PDN-U) and a component that handles control-plane data (PDN-C). The EPC may further include a Policy and Charging Rules Function (PCRF). Each entity, gateway, server, and function in the <NUM> core network can be implemented by specialized hardware (e.g., one or more devices), general hardware executing specialized software (e.g., at least one virtual machine executed on one or more devices), or the like.

The S1 interface(s) may include a first S1 interface interconnecting the MME of the <NUM> core network <NUM> and the master RAN <NUM>. In some cases, the S <NUM> interface(s) may include a second S <NUM> interface interconnecting the SGW of the <NUM> core network <NUM> and the master RAN <NUM>.

As illustrated in <FIG>, the NSA network including the master RAN <NUM>, the secondary RAN <NUM>, and the <NUM> core network <NUM> is consistent with Option 3X. However, implementations of the present disclosure can be adopted for other NSA architectures.

The single bearer RAN <NUM> may be associated with a <NUM> core network <NUM>. The <NUM> core network <NUM> may be, for example, a <NUM> Core (5GC). In some examples, various components of the 5GC can include, but are not limited to, a Network Exposure Function (NEF), a Network Resource Function (NRF), an Authentication Server Function (AUSF), an Access and Mobility management Function (AMF), a Policy Control Function (PCF), a Session Management Function (SMF), a Unified Data Management (UDM) function, a User Plane Function (UPF), and/or an Application Function (AF). Each entity, gateway, server, and function in the <NUM> core network can be implemented by specialized hardware (e.g., one or more devices), general hardware executing specialized software (e.g., at least one virtual machine executed on one or more devices), or the like.

In general, the AMF can be implemented as a network function including functionality to provide UE-based authentication, authorization, mobility management, etc., to various UEs. In some instances, the AMF can include functionality to terminate a RAN control plane interface between the UE <NUM> and other functions. In some instances, the AMF can include functionality to perform registration management of the UE <NUM> in the single bearer RAN <NUM> and/or <NUM> core network <NUM>, connection management, reachability management, mobility management, access authentication, access authorization, security anchor functionality (e.g., receiving and/or transmitting security keys during registration/authorization), and the like.

In general, the UPF can be implemented as a network function including functionality to control data transfer between the UE <NUM> and the various other components. In some instances, the UPF can include functionality to act as an anchor point for radio access technology (RAT) handover (e.g., inter and intra), external protocol data unit (PDU) session point of interconnect to an external network (e.g., the Internet), packet routing and forwarding, packet inspection and user plane portion of policy rule enforcement, traffic usage reporting, traffic routing, Quality of Service (QoS) handling for user plane (e.g., packet filtering, gating, uplink/downlink rate enforcement), uplink traffic verification, transport level packet marking in the uplink and downlink, downlink packet buffering and downlink data notification triggering, and the like. As can be understood in the context of this disclosure, there may be one or more UPFs, which are associated with the <NUM> core network <NUM> and/or with the UE <NUM>.

The single bearer RAN <NUM> may be connected to the <NUM> core network <NUM> by an N2 interface and/or an N3 interface. In various implementations, the N2 interface may interconnect the AMF in the <NUM> core network <NUM> and the single bearer RAN <NUM>. In some cases, the N3 interface may interconnect the UPF in the <NUM> core network <NUM> and the single bearer RAN <NUM>.

In various implementations, the <NUM> core network <NUM> and the <NUM> core network <NUM> may communicate over an N26 interface. In various implementations, the N26 interface can interconnect the MME in the <NUM> core network <NUM> and the AMF in the <NUM> core network <NUM>.

The UE <NUM> may be configured to communicate with one or more devices in at least one Wide Area Network (WAN) <NUM>. In some cases, the UE <NUM> may transmit data to, and receive data from, the device(s) of the WAN(s) <NUM> in one or more communication sessions. In various implementations, the WAN(s) <NUM> may include one or more Internet Protocol (IP) Multimedia Subsystem (IMS) networks, the Internet, or the like. According to various examples, the device(s) exchanging data with the UE <NUM> may be one or more other UEs, one or more content servers, or the like.

The UE <NUM> may exchange data with the device(s) of the WAN(s) <NUM> via a NSA network or a SA network. The NSA network may include the master RAN <NUM> and the secondary RAN <NUM> of the dual bearer RAN <NUM>, as well as the <NUM> core network <NUM>. The SA network may include the single bearer RAN <NUM> and the <NUM> core network <NUM>.

In some examples, the master RAN <NUM> of the dual bearer RAN <NUM> may cause a session between the UE <NUM> and the device(s) of the WAN(s) <NUM> to be handed over from the NSA network to the SA network. When the session is being provided by the NSA network, user plane data in the session may traverse the <NUM> core network <NUM>, at least one S1 interface between the master RAN <NUM> and the <NUM> core network <NUM>, the master RAN <NUM>, the <NUM> split bearer <NUM>, the X2 interface between the master RAN <NUM> and the secondary RAN <NUM>, the secondary RAN <NUM>, and the <NUM> split bearer <NUM>.

In various implementations, the master RAN <NUM> may transmit, over the <NUM> split bearer <NUM>, a message indicating a first threshold that can be used to assess a strength and/or quality of a signal received from the single bearer RAN <NUM>. In some cases, the message may further indicate a second threshold that can be used to asses a strength and/or quality of a signal received from the dual bearer RAN <NUM>. The signal received from the dual bearer RAN <NUM> may be a signal transmitted by the master RAN <NUM> over the <NUM> split bearer <NUM> and/or a signal transmitted by the secondary RAN <NUM> over the <NUM> split bearer <NUM>.

If the UE <NUM> determines that the strength and/or quality of the signal received from the single bearer RAN <NUM> exceeds the first threshold and/or that the strength and/or quality of the signal received from the dual bearer RAN <NUM> is lower than the second threshold, the UE <NUM> may transmit a report to the master RAN <NUM>. In response to receiving the report, the master RAN <NUM> may trigger handover from the NSA network to the SA network.

In some cases, the master RAN <NUM> may initiate handover from the <NUM> core network <NUM> to the <NUM> core network <NUM>. For instance, the master RAN <NUM> may transmit, over the S1 interface, a request to hand over the session to the <NUM> core network <NUM>. In response to the request, the <NUM> core network <NUM> may transmit, to the <NUM> core network <NUM>, a session transfer request over the N26 interface. Upon receiving the session, the <NUM> core network <NUM> may confirm that the session has been transferred by transmitting a message over the N26 interface. The <NUM> core network <NUM> may transmit a message, to the master RAN <NUM>, confirming that the session has been handed over to the <NUM> core network <NUM>.

In various examples, the master RAN <NUM> may initiate handover of the session from the dual bearer RAN <NUM> to the single bearer RAN <NUM>. According to some cases, the master RAN <NUM> may initiate the handover between the dual bearer RAN <NUM> and the single bearer RAN <NUM> in response to confirming that the session has been handed over to the <NUM> core network <NUM>. In example implementations, the master RAN <NUM> may transmit, to the UE <NUM> over the <NUM> split bearer <NUM>, a request to connect to the single bearer RAN <NUM>. In response, the UE <NUM> may establish a connection with the single bearer RAN <NUM> and exchange data with the single bearer RAN <NUM> over the single <NUM> bearer <NUM>. The dual bearer RAN <NUM> may also transmit context data associated with the session to the single bearer RAN <NUM> (e.g., via a network path including the S1 interface(s), the <NUM> core network <NUM>, the N26 interface, the <NUM> core network <NUM>, and the N2 and/or N3 interface), which the single bearer RAN <NUM> can utilize to continue the session.

In various implementations, because the session has already been handed over to the <NUM> core network <NUM>, the UE <NUM> may continue the session with the device(s) of the WAN(s) <NUM> using the single <NUM> bearer <NUM>. Accordingly, the session may be supported by the SA network, such that user plane data in the session may traverse the <NUM> core network <NUM>, the N3 interface between the single bearer RAN <NUM> and the <NUM> core network <NUM>, the single bearer RAN <NUM>, and the single <NUM> bearer <NUM>.

In some examples, the single bearer RAN <NUM> may cause a session between the UE <NUM> and the device(s) of the WAN(s) <NUM> to be handed over from the SA network to the NSA network. When the session is being provided by the SA network, user plane data may traverse the <NUM> core network <NUM>, the N3 interface between the single bearer RAN <NUM> and the <NUM> core network <NUM>, the single bearer RAN <NUM>, and the single <NUM> bearer <NUM>.

In various implementations, the single bearer RAN <NUM> may transmit, over the single <NUM> bearer <NUM>, a message indicating a third threshold that can be used to assess a strength and/or quality of a signal received from the dual bearer RAN <NUM>. The signal received from the dual bearer RAN <NUM> may be a signal transmitted by the master RAN <NUM> over the <NUM> split bearer <NUM> and/or a signal transmitted by the secondary RAN <NUM> over the <NUM> split bearer <NUM>.

If the UE <NUM> determines that the strength and/or quality of the signal received from the dual bearer RAN <NUM> exceeds the third threshold, the UE <NUM> may transmit a report to the single bearer RAN <NUM>. In response to receiving the report, the single bearer RAN <NUM> may trigger handover from the SA network to the NSA network.

In some cases, the single bearer RAN <NUM> may initiate handover from the <NUM> core network <NUM> to the <NUM> core network <NUM>. For instance, the single bearer RAN <NUM> may transmit, over the N2 interface, a request to a component in the <NUM> core network <NUM> (e.g., the MME in the <NUM> core network <NUM>) to hand over the session to the <NUM> core network <NUM>. In response to the request, the <NUM> core network <NUM> (e.g., the MME in the <NUM> core network <NUM>) may transmit, to the <NUM> core network <NUM>, a session transfer request over the N26 interface. Upon receiving the session, the <NUM> core network <NUM> may confirm that the session has been transferred by transmitting a message to the <NUM> core network <NUM> over the N26 interface. The <NUM> core network <NUM> may transmit a message, to the single bearer RAN <NUM>, confirming that the session has been handed over to the <NUM> core network <NUM>.

In various examples, the single bearer RAN <NUM> may initiate handover of the session from the single bearer RAN <NUM> to the dual bearer RAN <NUM>. According to some cases, the single bearer RAN <NUM> may initiate the handover between the single bearer RAN <NUM> and the dual bearer RAN <NUM> in response to confirming that the session has been handed over to the <NUM> core network <NUM>. In example implementations, the single bearer RAN <NUM> may transmit, to the UE <NUM> over the single <NUM> bearer <NUM>, a request to connect to the dual bearer RAN <NUM>. In response, the UE <NUM> may establish a connection with the dual bearer RAN <NUM> and exchange data with the master RAN <NUM> over the <NUM> split bearer <NUM> and with the secondary RAN <NUM> over the <NUM> split bearer <NUM>. The single bearer RAN <NUM> may also transmit context data associated with the session to the dual bearer RAN <NUM> (e.g., via a network path including the N2 and/or N3 interface, the <NUM> core network <NUM>, the N26 Interface, the <NUM> core network <NUM>, and the S1 interface(s)), which the dual bearer <NUM> can utilize to continue the session.

In various implementations, because the session has already been handed over to the <NUM> core network <NUM>, the UE <NUM> may continue the session with the device(s) of the WAN(s) <NUM> using the <NUM> split bearer <NUM> and the <NUM> split bearer <NUM>. Accordingly, the session may be supported by the NSA network, such that user plane data in the session may traverse the <NUM> core network <NUM>, at least one S1 interface between the master RAN <NUM> and the <NUM> core network <NUM>, the master RAN <NUM>, the <NUM> split bearer <NUM>, the X2 interface between the master RAN <NUM> and the secondary RAN <NUM>, the secondary RAN <NUM>, and the <NUM> split bearer <NUM>.

<FIG> illustrates example signaling <NUM> for performing handover of a session between a Non-Standalone (NSA) network and a Standalone (SA) network. The signaling <NUM> includes data transmitted and/or received by the User Equipment (UE) described above with reference to <FIG> and <FIG>. In addition, the signaling <NUM> includes data transmitted and/or received by a first Radio Access Network (RAN) <NUM>, a first core network <NUM>, a second RAN <NUM>, and a second core network <NUM>. In various examples, the first RAN <NUM> may be one of the dual bearer RAN <NUM> or the single bearer RAN <NUM> described above with reference to <FIG> and <FIG>, and the second RAN <NUM> may be the other one of the dual bearer RAN <NUM> or the single bearer RAN <NUM>. Similarly, in various implementations, the first core network <NUM> may be one of the <NUM> core network <NUM> or the <NUM> core network <NUM> described above with reference to <FIG>, and the second core network <NUM> may be the other one of the <NUM> core network <NUM> or the <NUM> core network <NUM>. According to example implementations, the first RAN <NUM> and the first core network <NUM> may be part of one of the NSA network or the SA network, and the second RAN <NUM> and the second core network <NUM> may be part of the other one of the NSA network or the SA network.

As illustrated in <FIG>, first user plane data <NUM> is exchanged between the UE <NUM> and the first core network <NUM> via the first RAN <NUM>. The first user plane data <NUM> may be part of a communication session between the UE <NUM> and another device. Services (e.g., data services) can be delivered to the UE <NUM> via the first user plane data <NUM>, in various examples.

For instance, in scenarios in which the first core network <NUM> is an Evolved Packet Core (EPC), the first user plane data <NUM> may be transmitted over a default bearer (e.g., Quality of Service (QoS) Class Identifier (QCI) <NUM>, QCI <NUM>, or the like). In some examples in which the first core network <NUM> is a 5GC, the first user plane data <NUM> may be transmitted over a default <NUM> QoS Identifier (5QI) (e.g., 5QI6, 5QI9, or the like).

In some cases in which the first RAN <NUM> is a dual bearer RAN, the first user plane data <NUM> may be transmitted from an eNodeB to the UE <NUM> over a Secondary Cell Group (SCG) bearer, to a gNodeB via SCG over an X2 interface, and to the UE <NUM> via a split bearer provided by the gNodeB.

The first RAN <NUM> may transmit a threshold indicator <NUM> to the UE <NUM>. In some cases, the threshold indicator <NUM> may include at least one signal strength threshold and/or signal quality threshold. Some examples of a signal strength threshold include a power threshold, such as a Received Signal Strength Indicator (RSSI), a Reference Signal Received Power (RSRP), or the like. Some example of a signal quality threshold may include a Reference Signal Received Quality (RSRQ), a Signal to Interference plus Noise Ratio (SINR), or the like. The threshold indicator <NUM> may further indicate at least one signal to compare to the threshold(s). For instance, the threshold indicator <NUM> may indicate a radio signal from the second RAN <NUM>, such as a test signal <NUM>. In some cases, the threshold indicator <NUM> may further indicate a radio signal from the first RAN <NUM> to compare to the threshold(s). In various implementations, the threshold indicator <NUM> may specify one or more thresholds indicative of a B2 event, an A4 event, or the like.

In various instances, the threshold indicator <NUM> may comprise a Radio Resource Control (RRC) connection reconfiguration message. The RRC message may have a measurement control element specifying that a wireless band utilized by the second RAN <NUM> has the highest priority of any bands utilized by the first RAN <NUM> or other local RANs. For instance, if the second RAN <NUM> utilizes n71, the RRC connection reconfiguration may specify that n71 is the highest priority for wireless communication by the UE <NUM>.

The second RAN <NUM> may transmit the test signal <NUM> to the UE <NUM>. The UE <NUM> may compare the test signal <NUM> to at least one of the threshold(s). For example, the UE <NUM> may determine that the test signal <NUM> has a signal strength that exceeds a signal strength threshold indicated in the threshold indicator <NUM>. In some cases, the UE <NUM> may determine that the test signal <NUM> has a signal quality that exceeds a signal quality threshold indicated in the threshold indicator <NUM>.

In some implementations, the UE <NUM> may further compare a radio signal (not illustrated) received from the first RAN <NUM> to at least one of the threshold(s). For instance, the UE <NUM> may determine that the signal from the first RAN <NUM> has a signal strength that is less than a signal strength threshold indicated in the threshold indicator <NUM>. In various examples, the UE <NUM> may determine that the signal has a signal quality that is less than a signal quality threshold indicated in the threshold indicator <NUM>.

In response to identifying that the test signal <NUM> meets a threshold provided by the threshold indicator <NUM> (and, in some cases, that the signal from the first RAN <NUM> is below a threshold provided by the threshold indicator <NUM>), the UE <NUM> may transmit a measurement report <NUM> to the first RAN <NUM>. The measurement report <NUM> may indicate that the threshold(s) specified by the threshold indicator <NUM> has been satisfied.

Upon receiving the measurement report <NUM>, the first RAN <NUM> may initiate handover of the session from the first core network <NUM> to the second core network <NUM>. The first RAN <NUM> may transmit, to the second core network <NUM>, a first handover request <NUM>. The first handover request <NUM> may be, for instance, a handover preparation message. The first core network <NUM> may relay the first handover request <NUM> between the first RAN <NUM> and the second core network <NUM>. In response to receiving the first handover request <NUM>, the first core network <NUM> and the second core network <NUM> may cause the session to be handed over from the first core network <NUM> to the second core network <NUM>.

In various implementations, the first handover request <NUM> may identify the session. For instance, the first handover request <NUM> may identify the UE <NUM>, the first RAN <NUM>, the first core network <NUM>, a type of services exchanged in the first user plane data <NUM>, a device exchanging the first user plane data <NUM> with the UE <NUM> via the first RAN <NUM> and the first core network <NUM>, or the like. Accordingly, the first core network <NUM> and/or the second core network <NUM> may arrange session handover.

In various implementations, the first core network <NUM> may transmit, to the second core network <NUM>, a session transfer message. The session transfer message may establish an equivalent bearer or data flow in the second core network <NUM> that was served by the first core network <NUM> to deliver the first user plane data <NUM>. For instance, if the first core network <NUM> is an EPC and the second core network <NUM> is a 5GC, the second core network <NUM> may establish a <NUM> QoS Indicator (5QI) (e.g., 5QI6) equivalent to the QCI previously used by the first core network <NUM> (e.g., QCI6) to provide the first user plane data <NUM> to the UE <NUM>. In some examples, if the first core network <NUM> is a 5GC and the second core network <NUM> is an EPC, the second core network <NUM> may establish a QCI for the session that is equivalent to a 5QI previously used by the first core network <NUM> to provide the first user plane data <NUM> to the UE <NUM>.

In response to accepting the session, the second core network <NUM> may transmit a handover confirmation <NUM> to the first RAN <NUM>. The first core network <NUM> may relay the handover confirmation <NUM> from the second core network <NUM> to the first RAN <NUM>. The handover confirmation <NUM> may inform the first RAN <NUM> that the session has been handed over from the first core network <NUM> to the second core network <NUM>.

In response to receiving the handover confirmation <NUM>, the first RAN <NUM> may initiate handover of the session from the first RAN <NUM> to the second RAN <NUM>. The first RAN <NUM> may transmit a second handover request <NUM> to the UE <NUM>. In various implementations, the second handover request <NUM> may identify the second RAN <NUM>. In some cases, the second handover request <NUM> may include an RRC connection request.

According to some implementations, the first RAN <NUM> may also transmit, to the UE <NUM>, an RRC connection reconfiguration message requesting that the existing bearer between the first RAN <NUM> and the UE <NUM> (e.g., the SCG bearer) be removed. In some cases, the UE <NUM> may respond by transmitting, to the first RAN <NUM>, an RRC connection reconfiguration complete message confirming that the existing bearer has been removed.

In accordance with the second handover request <NUM>, the UE <NUM> may transmit a connection request <NUM> to the second RAN <NUM>. In some cases, the UE <NUM> may attach to, exchange Session Initiation Protocol (SIP) messages, and/or synchronize with the second RAN <NUM>. The connection request <NUM> may identify the existing session. Accordingly, the second RAN <NUM> may accept the session. Upon accepting the session, the second RAN <NUM> may transmit a connection confirmation <NUM> to the UE <NUM>.

Once the session has been handed over to the second core network <NUM>, as well as to the second RAN <NUM>, the UE <NUM> and the second core network <NUM> may exchange second user plane data <NUM>. The second user plane data <NUM> may be relayed between the UE <NUM> and the second core network <NUM> by the second RAN <NUM>. The second user plane data <NUM> may be part of the same session as the first user plane data <NUM>.

Although not illustrated in <FIG>, the first RAN <NUM> may receive third user plane data in the session during the signaling <NUM>. The third user plane data may represent context data in the session. For instance, the first RAN <NUM> may receive at least a portion of the third user plane data from the first core network <NUM> prior to the session being handed over from the first core network <NUM> to the second core network <NUM>. In some cases, the first RAN <NUM> may receive at least a portion of the third user plane data from the UE <NUM> prior to the session being handed over from the first RAN <NUM> to the second RAN <NUM>. In various implementations, the first RAN <NUM> may transmit the third user plane data to the second RAN <NUM> in response to transmitting the second handover request <NUM> to the UE <NUM>. Accordingly, the third user plane data may be prevented from being lost as the session is handed over from the first RAN <NUM> and the first core network <NUM> to the second RAN <NUM> and the second core network <NUM>.

Because the first RAN <NUM> may exchange the first user plane data <NUM> with a first one of a dual bearer and a single bearer, and the second RAN <NUM> may exchange the second user plane data <NUM> with the other one of the dual bearer and the single bearer, the signaling <NUM> can be used to hand over a session from a NSA network to a SA network and/or to hand over a session from an SA network to a NSA network. In various implementations, resources in the NSA network can be conserved while also ensuring that high-throughput and low-latency <NUM> services can be consistently delivered to the UE <NUM>.

<FIG> and <FIG> illustrate example processes in accordance with embodiments of the disclosure. These processes are illustrated as logical flow graphs, each operation of which represents a sequence of operations that can be implemented in hardware, software, or a combination thereof. In the context of software, the operations represent computer-executable instructions stored on one or more computer-readable storage media that, when executed by one or more processors, perform the recited operations. Generally, computer-executable instructions include routines, programs, objects, components, data structures, and the like that perform particular functions or implement particular abstract data types. The order in which the operations are described is not intended to be construed as a limitation, and any number of the described operations can be combined in any order and/or in parallel to implement the processes.

<FIG> illustrates a process <NUM> for handing over a session between a network having a Non-Standalone (NSA) architecture and a network having a Standalone (SA) architecture. In various implementations, the process <NUM> can be performed by a base station, a Radio Access Network (RAN) (e.g., the dual bearer RAN <NUM>, the single bearer RAN <NUM>, the master RAN <NUM>, the secondary RAN <NUM>, etc.), an Access Point (AP), or the like. In various cases, the process <NUM> can be performed by a component in a network (e.g., the network having the NSA architecture or the network having the SA architecture) from which the session is being handed over.

At <NUM>, a measurement report is received from a User Equipment (UE) associated with a communication session. In various implementations, an indication of one or more thresholds may be transmitted to the UE. For instance, a first threshold to compare to a signal transmitted to the UE by a dual bearer RAN and/or a second threshold to compare to a signal transmitted to the UE by a single bearer RAN may be transmitted to the UE (e.g., by the entity performing the process <NUM>). Each one of the thresholds may be a signal strength threshold, a signal quality threshold, or the like. The UE may receive signals from the dual bearer RAN and/or the single bearer RAN and compare the signals to the first threshold and/or the second threshold. Based on the comparisons, the UE may transmit the measurement report.

In some implementations, the UE may be receiving services (e.g., data services) in the communication session from a NSA network. The NSA network may transmit a first threshold to compare to a signal transmitted by the NSA network and a second threshold to compare to a signal transmitted by an SA network. If the signal transmitted by the NSA network is below the first threshold and the signal transmitted by the SA network is above the second threshold, the UE may generate and transmit the measurement report to the entity performing the process <NUM>.

In example implementations, the UE may be receiving services in the communication session from an SA network. The SA network may transmit a third threshold to compare to a signal transmitted by an NSA network. If the signal transmitted by the NSA network is above the third threshold, the UE may generate and transmit the measurement report to the entity performing the process <NUM>.

At <NUM>, handover of the communication session from a first core network to a second core network is initiated. In various implementations, <NUM> may include transmitting, to the first core network, a request to hand over the communication session to the second core network. The first core network may forward the request to the second core network. The first core network and/or the second core network may handover the communication session from the first core network to the second core network.

In some implementations, the UE may be receiving services in the communication session from the NSA network. The first core network may be a <NUM> core network. The second core network may be a <NUM> core network.

In some cases, the UE may be receiving services in the communication session from the SA network. The first core network may be a <NUM> core network. The second core network may be a <NUM> core network.

At <NUM>, handover of the communication session between a single radio bearer and a dual radio bearer is initiated. In various examples, a handover confirmation message may be received from the first core network and/or the second core network. The handover confirmation message may indicate that core handover has been performed.

In response to receiving the handover confirmation message, the entity performing <NUM> may perform <NUM>. In various examples, a handover request may be transmitted to the UE. The UE may be connected to a first RAN associated with the first core network. The handover request may cause the UE to connect to a second RAN associated with the second core network. In various implementations, the first RAN may be one of a dual bearer RAN and a single bearer RAN, and the second RAN may be the other one of the dual bearer RAN and the single bearer RAN. Accordingly, in various examples, the process <NUM> may be utilized to hand over a session between an NSA network and an SA network.

<FIG> illustrates a process <NUM> for transferring session context during handover between a network having a Non-Standalone (NSA) architecture and a network having a Standalone (SA) architecture. In various implementations, the process <NUM> can be performed by a base station, a Radio Access Network (RAN) (e.g., the dual bearer RAN <NUM>, the single bearer RAN <NUM>, the master RAN <NUM>, the secondary RAN <NUM>, etc.), an Access Point (AP), or the like. In various cases, the process <NUM> can be performed by a component in a network (e.g., the network having the NSA architecture or the network having the SA architecture) from which the session is being handed over.

At <NUM>, handover of a session from a first network to a second network is initiated. The session may include the exchange of user plane data between a User Equipment (UE) and another device via the first network. The first network may have a first architecture and the second network may have a second architecture. For instance, the first network may have an NSA network architecture and the second network may have an SA network architecture. In some cases, the first network may have an SA network architecture and the second network may have an NSA network architecture.

In various implementations, the first network (e.g., a first RAN in the first network) may initiate handover of the session from a first core network in the first network to a second core network in the second network. In example implementations, the first core network may be a <NUM> core network and the second core network may be a <NUM> core network, or the first core network may be a <NUM> core network and the second core network may be a <NUM> core network. In some cases, after the session has been handed over from the first core network to the second core network, the first RAN in the first network may initiate handover of the session from the first RAN to a second RAN in the second network. The handover from the first RAN to the second RAN may be initiated by transmitting a handover request to the UE. In various examples, the first RAN may be a dual bearer RAN and the second RAN may be a single bearer RAN, or the first RAN may be a single bearer RAN and the second RAN may be a dual bearer RAN.

At <NUM>, user plane data in the session is received. According to some cases, the user plane data may be received by the first RAN from the first network between a first time point at which the handover from the first core network to the second core network is initiated and a second time point at which the handover from the first core network to the second core network is completed. In various examples, the user plane data may be received by the first RAN from the UE between the second time point and a third time point at which the handover of the session from the first RAN to the second RAN has been initiated.

At <NUM>, the handover is determined to be completed. In some cases, the handover may be determined to be completed in response to the first RAN transmitting the handover request to the UE. In various examples, the handover may be determined to be completed in response to waiting a predetermined period of time (e.g., <NUM>-<NUM> milliseconds) after the handover request has been transmitted to the UE. In some implementations, a confirmation that the handover has been completed may be received from the second RAN, the UE, or a combination thereof. Upon completion of the handover, the session may be handed over to the second core network as well as the second RAN.

At <NUM>, the user plane data is transmitted to the second network. In various implementations, the user plane data may be transmitted to the second RAN in the second network. The second RAN may forward the user plane data to its destination (e.g., to the UE or to the device communicating with the UE). Accordingly, the user plane data that is received by the first RAN during handover latency may be retained during the handover process.

<FIG> illustrates example devices <NUM> configured to initiate handover between a Non-Standalone (NSA) network and a Standalone (SA) network. In some embodiments, some or all of the functionality discussed in connection with <FIG> can be implemented in the device(s) <NUM>. Further, the device(s) <NUM> can be implemented as one or more server computers, at least one network element on a dedicated hardware, as at least one software instance running on a dedicated hardware, or as at least one virtualized function instantiated on an appropriate platform, such as a cloud infrastructure, and the like. It is to be understood in the context of this disclosure that the device(s) <NUM> can be implemented as a single device or as a plurality of devices with components and data distributed among them.

As illustrated, the device(s) <NUM> can include one or more radio devices <NUM> and one or more core devices <NUM>. The radio device(s) <NUM> may comprise, for instance, an eNodeB, a gNodeB, or any other device configured to transmit and/or receive data wirelessly from an external device (e.g., a User Equipment (UE)). The radio device(s) <NUM> can comprise a memory <NUM>. In various embodiments, the memory <NUM> is volatile (including a component such as Random Access Memory (RAM)), non-volatile (including a component such as Read Only Memory (ROM), flash memory, etc.) or some combination of the two.

The memory <NUM> may include various components, such as a handover initiator <NUM>. The handover initiator <NUM> can comprise methods, threads, processes, applications, or any other sort of executable instructions. The handover initiator <NUM>, and various other elements stored in the memory <NUM>, can also include files and databases.

The memory <NUM> may include various instructions (e.g., instructions in the handover initiator <NUM>), which can be executed by at least one processor <NUM> to perform operations. In some embodiments, the processor(s) <NUM> includes a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), or both CPU and GPU, or other processing unit or component known in the art.

The radio device(s) <NUM> can also include additional data storage devices (removable and/or non-removable) such as, for example, magnetic disks, optical disks, or tape. Such additional storage can include removable storage <NUM> and non-removable storage <NUM>. Tangible computer-readable media can include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. The memory <NUM>, removable storage <NUM>, and non-removable storage <NUM> are all examples of computer-readable storage media. Computer-readable storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Discs (DVDs), Content-Addressable Memory (CAM), or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by the radio device(s) <NUM>. Any such tangible computer-readable media can be part of the radio device(s) <NUM>.

The radio device(s) <NUM> also can include input device(s) <NUM>, such as a keypad, a cursor control, a touch-sensitive display, voice input device, etc., and output device(s) <NUM> such as a display, speakers, printers, etc. These devices are well known in the art and need not be discussed at length here. In particular implementations, a user can provide input to the radio device(s) <NUM> via a user interface associated with the input device(s) <NUM> and/or the output device(s) <NUM>.

The radio device(s) <NUM> can also include one or more wired or wireless transceiver(s) <NUM>. For example, the transceiver(s) <NUM> can include a Network Interface Card (NIC), a network adapter, a Local Area Network (LAN) adapter, or a physical, virtual, or logical address to connect to the various base stations or networks contemplated herein, for example, or the various user devices and servers. To increase throughput when exchanging wireless data, the transceiver(s) <NUM> can utilize Multiple-Input/Multiple-Output (MIMO) technology. The transceiver(s) <NUM> can include any sort of wireless transceivers capable of engaging in wireless, Radio Frequency (RF) communication. The transceiver(s) <NUM> can also include other wireless modems, such as a modem for engaging in Wi-Fi, WiMAX, Bluetooth, or infrared communication.

In some implementations, the transceiver(s) <NUM> can be used to communicate between various functions, components, modules, or the like, that are comprised in the devices <NUM>. For instance, the transceiver(s) <NUM> can be used to transmit data between the radio device(s) <NUM> and an external User Equipment (UE), between the radio device(s) <NUM> and the core device(s) <NUM>, or the like.

In various implementations, the radio device(s) <NUM> may support dual and/or single connectivity. For instance, the transceiver(s) <NUM> may support communication with the UE via a dual bearer or a single bearer. In some cases, the transceiver(s) <NUM> are configured to transmit and/or receive data wirelessly over one or more <NUM>-specific radio resources, one or more <NUM>-specific radio resources, or a combination thereof.

In various examples, the core device(s) <NUM> can include at least one of a <NUM> core network, a <NUM> core network, a <NUM> core network (e.g., an Evolved Packet Core (EPC)), or a <NUM> core network. For instance, the core device(s) <NUM> may include an EPC or <NUM> core network.

The core device(s) <NUM> can comprise a memory <NUM>. In various embodiments, the memory <NUM> is volatile (including a component such as RAM), non-volatile (including a component such as ROM, flash memory, etc.) or some combination of the two.

The memory <NUM> may include various components, such as core instruction(s) <NUM>. The core instruction(s) <NUM> can comprise methods, threads, processes, applications, or any other sort of executable instructions. The core instruction(s) <NUM>, and various other elements stored in the memory <NUM> can also include files and databases.

The memory <NUM> may include various instructions (e.g., instructions in the core instruction(s) <NUM>), which can be executed by at least one processor <NUM> to perform operations. In some embodiments, the processor(s) <NUM> includes a CPU, a GPU, or both CPU and GPU, or other processing unit or component known in the art.

The core device(s) <NUM> can also include additional data storage devices (removable and/or non-removable) such as, for example, magnetic disks, optical disks or tape. Such additional storage can include removable storage <NUM> and non-removable storage <NUM>. Tangible computer-readable media can include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. The memory <NUM>, removable storage <NUM>, and non-removable storage <NUM> are all examples of computer-readable storage media. Computer-readable storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, DVDs, CAM, or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by the core device(s) <NUM>. Any such tangible computer-readable media can be part of the core device(s) <NUM>.

The core device(s) <NUM> also can include input device(s) <NUM>, such as a keypad, a cursor control, a touch-sensitive display, voice input device, etc., and output device(s) <NUM> such as a display, speakers, printers, etc. These devices are well known in the art and need not be discussed at length here. In particular implementations, a user can provide input to the core device(s) <NUM> via a user interface associated with the input device(s) <NUM> and/or the output device(s) <NUM>.

The core device(s) <NUM> can also include one or more wired or wireless transceiver(s) <NUM>. For example, the transceiver(s) <NUM> can include a NIC, a network adapter, a LAN adapter, or a physical, virtual, or logical address to connect to the various base stations or networks contemplated herein, for example, or the various user devices and servers. To increase throughput when exchanging wireless data, the transceiver(s) <NUM> can utilize MIMO technology. The transceiver(s) <NUM> can include one or more wireless transceivers capable of engaging in wireless, RF communication. The transceiver(s) <NUM> can also include other wireless modems, such as a modem for engaging in Wi-Fi, WiMAX, Bluetooth, or infrared communication.

In some implementations, the transceiver(s) <NUM> can be used to communicate between various functions, components, modules, or the like, that are comprised in the device(s) <NUM>. For instance, the transceiver(s) <NUM> can be used to transmit data between the core device(s) <NUM> and the radio device(s) <NUM>, between the core device(s) <NUM> and another network (e.g., an IP Multimedia Subsystem (IMS) network, data network, the Internet, another core network, etc.), or the like.

Claim 1:
A method performed by a dual-bearer Radio Access Network, RAN, (<NUM>, <NUM>) or by a single bearer RAN (<NUM>, <NUM>), the method comprising:
receiving (<NUM>), from a User Equipment, UE (<NUM>), a measurement report (<NUM>) indicating that a signal threshold has been satisfied;
in response to receiving the measurement report, initiating (<NUM>, <NUM>, <NUM>) handover of a communication session associated with the UE from a first core network (<NUM>, <NUM>, <NUM>) associated with the dual-bearer Radio Access Network, RAN, (<NUM>, <NUM>) or the single bearer RAN (<NUM>, <NUM>) to a second core network (<NUM>, <NUM>, <NUM>) associated with the single bearer RAN (<NUM>, <NUM>) or the dual-bearer Radio Access Network, RAN, (<NUM>, <NUM>) respectively;
receiving a message confirming (<NUM>) that the communication session has been handed over from the first core network to the second core network; and
in response to receiving the message, initiating (<NUM>, <NUM>), handover of the communication session between a single radio bearer associated with a first Radio Access Technology , RAT, and a dual radio bearer (<NUM>, <NUM>, <NUM>) associated with the first RAT and a second RAT;
the single radio bearer (<NUM>) being provided by the single bearer RAN (<NUM>, <NUM>) and the dual radio bearer (<NUM>) being provided by the dual-bearer RAN, (<NUM>, <NUM>).