User equipment context transfer over radio access network paging

This document describes methods and systems for user equipment (UE) context transfer over radio access network (RAN) paging. A first base station receives from a second base station a first message that includes a context that is associated with a user equipment while the user equipment was in an engaged mode with the second base station. The first base station transmits a second message that is a paging message to the user equipment and in response receives, from the user equipment, a third message that includes a resume message authentication code identifier. After the first base station verifies the third message using the resume message authentication code identifier, the first base station transmits, to the user equipment, a fourth message that enables the user equipment to resume the engaged mode with the first base station in accordance with the context.

BACKGROUND

A user equipment (UE) may, in certain instances, enter a radio resource control (RRC) connected state with a base station to receive downlink transmissions from a wireless network supported by the base station. While in the RRC connected state, the UE may communicate with the wireless network via the base station under conditions that relate to bit rates, mobility restrictions, security capabilities, signaling references, protocol data unit session resources, and the like. Today it is common for an Access and Mobility Function (AMF) of the wireless network to manage these conditions, otherwise referred to as user equipment contexts, as part of administering communications across a wireless network.

In certain instances, such as when there is an absence of downlink transmissions from the network to the UE via the base station, the base station may cause the UE to enter an RRC inactive state by sending the UE an RRC release message with a suspend configuration. In the event the network needs to resume downlink transmissions to the UE, it is possible that the UE has moved and that the UE needs to enter the RRC connected state with another base station before the downlink transmissions resume. In such a situation, resumption of the downlink transmissions is delayed while the other base station retrieves the user equipment contexts from the base station that previously caused the UE to enter the RRC inactive state.

SUMMARY

This summary is provided to introduce subject matter that is further described in the Detailed Description and Drawings. Accordingly, this Summary should not be considered to describe essential features nor used to limit the scope of the claimed subject matter.

In some aspects, a method performed by a first base station of two base stations is described. The method comprises the first base station receiving from a second base station a first message that includes a context of a user equipment that was previously in an engaged mode with the second base station. In response, the first base station transmits to the user equipment a second message that includes a radio network temporary identifier that identifies the context. The first base station then receives, from the user equipment, a third message that includes a resume message authentication code identifier (MAC-I). After the first base station verifies the third message using the resume MAC-I, the base station transmits, to the user equipment, a fourth message that enables the user equipment to resume the engaged mode with the first base station in accordance with the context.

In some other aspects, a method performed by a user equipment is described. The method comprises the user equipment discontinuing an engaged mode with a second base station to enter a disengaged mode. The user equipment then receives from a first base station a first message that includes a radio network temporary identifier that identifies a context of the user equipment while the user equipment was in the engaged mode with the second base station. In response, the user equipment transmits a second message to the first base station that includes a resume message authentication code identifier (MAC-I) and causes the first base station to verify, using the resume MAC-I, the second message. In response to the first base station verifying the second message, the user equipment receives, from the first base station, a third message that causes the user equipment to resume the engaged mode with the first base station in accordance with the context.

The invention also provides other methods, such as a corresponding method performed by the second base station, and a corresponding method performed by the first and second base stations and the user equipment in combination. The invention also provides apparatus corresponding to the described methods such as each of a first base station, a second base station, and a user equipment, each arranged to put into effect the described corresponding method steps. The invention also provides computer program code arranged to put into effect the described methods when implemented on suitable data processing equipment, and computer-readable media carrying such computer program code.

The details of one or more implementations of common search space configuration and system information acquisition are set forth in the accompanying drawings and the following description. Other features and advantages will be apparent from the description and drawings, and from the claims. This summary is provided to introduce subject matter that is further described in the Detailed Description and Drawings. Accordingly, a reader should not consider the summary to describe essential features nor limit the scope of the claimed subject matter.

DETAILED DESCRIPTION

This document describes methods and systems for user equipment (UE) context transfer over radio access network (RAN) paging. As part of the methods and systems, a first base station receives from a second base station a first message that is a paging message and includes a context associated with a UE while the UE was in an engaged mode with the second base station. The first base station transmits a second message to the UE that is a paging message and in response receives, from the user equipment, a third message that includes a resume message authentication code identifier (MAC-I). After the first base station verifies the third message using the resume MAC-I, the base station transmits, to the UE, a fourth message that enables the UE to resume the engaged mode with the first base station in accordance with the context.

A context manager application is described in this document. The context manager application may cause a base station to perform operations that are directed to management of contexts that may be associated with a user equipment, including verification of messages received from the user equipment.

Operating Environment

FIG.1illustrates an example environment100, which includes multiple user equipment110(UE110), illustrated as UE111, UE112, and UE113. Each UE110can communicate with base stations120(illustrated as base stations121,122,123, and124) through one or more wireless communication links130(wireless link130), illustrated as wireless links131and132. For simplicity, the UE110is implemented as a smartphone but may be implemented as any suitable computing or electronic device, such as a mobile communication device, modem, cellular phone, gaming device, navigation device, media device, laptop computer, desktop computer, tablet computer, smart appliance, vehicle-based communication system, or an Internet-of-Things (IoT) device such as a sensor or an actuator. The base stations120(e.g., an Evolved Universal Terrestrial Radio Access Network Node B, E-UTRAN Node B, evolved Node B, eNodeB, eNB, Next Generation Node B, gNode B, gNB, ng-eNB, or the like) may be implemented in a macrocell, microcell, small cell, picocell, or the like, or any combination thereof.

The base stations120communicate with the UE110using the wireless links131and132, which may be implemented as any suitable type of wireless link. The wireless links131and132include control and data communication, such as downlink of data and control information communicated from the base stations120to the UE110, uplink of other data and control information communicated from the UE110to the base stations120, or both. The wireless links130may include one or more wireless links (e.g., radio links) or bearers implemented using any suitable communication protocol or standard, or combination of communication protocols or standards, such as 3rd Generation Partnership Project Long-Term Evolution (3GPP LTE), Fifth Generation New Radio (5G NR), and so forth. Multiple wireless links130may be aggregated in a carrier aggregation to provide a higher data rate for the UE110. Multiple wireless links130from multiple base stations120may be configured for Coordinated Multipoint (CoMP) communication with the UE110.

The base stations120are collectively a Radio Access Network140(e.g., RAN, Evolved Universal Terrestrial Radio Access Network, E-UTRAN, 5G NR RAN or NR RAN). The RANs140are illustrated as an NR RAN141and an E-UTRAN142. The base stations121and123in the NR RAN141are connected to a Fifth Generation Core150(5GC150) network. The base stations122and124in the E-UTRAN142are connected to an Evolved Packet Core160(EPC160). Optionally or additionally, the base station122may connect to both the 5GC150and EPC160networks.

The base stations121and123connect, at102and104respectively, to the 5GC150through an NG2 interface for control-plane signaling and using an NG3 interface for user-plane data communications. The base stations122and124connect, at106and108respectively, to the EPC160using an Si interface for control-plane signaling and user-plane data communications. Optionally or additionally, if the base station122connects to the 5GC150and EPC160networks, the base station122connects to the 5GC150using an NG2 interface for control-plane signaling and through an NG3 interface for user-plane data communications, at180.

In addition to connections to core networks, the base stations120may communicate with each other. For example, the base stations121and123communicate using an Xn Application Protocol (XnAP) through an Xn interface at103, the base stations122and123communicate through an Xn interface at105, and the base stations122and124communicate through an X2 interface at107.

The 5GC150includes an Access and Mobility Management Function152(AMF152), which provides control-plane functions, such as registration and authentication of multiple UE110, authorization, and mobility management in the 5G NR network. The EPC160includes a Mobility Management Entity162(MME162), which provides control-plane functions, such as registration and authentication of multiple UE110, authorization, or mobility management in the E-UTRA network. The AMF152and the MME162communicate with the base stations120in the RANs140and also communicate with multiple UE110, using the base stations120.

Furthermore, and within the operating environment100, contexts associated with the UE110(e.g., bit rates, mobility restrictions, security capabilities, signaling references, protocol data unit session resources), may be communicated via radio access network (RAN) paging messages as part of managing wireless communications within the operating environment100. In general, a portion of a wireless communication protocol (e.g., a portion of wireless communication document 3GPP TS 38.331) may specify techniques associated with using RAN paging messages to transmit context information that may be associated with the UE110after it is no longer engaged with a base station.

For example, context information of the user equipment110operating in an engaged mode with the base station123may be saved by the base station123upon the UE110disconnecting from the base station123. As part of managing wireless communications, the base station123may transmit, via a RAN paging message, the context information to the base station121via the Xn interface at103, enabling the UE110to enter (or resume) the engaged mode with the base station121.

Other examples may include the paging message (that includes the context information) being transmitted via the X2 interface107(in an instance where the UE110disconnects from a base station within the EPC160network and remains within the EPC160network) or the paging message being transmitted via the NG3 interface180(in an instance where the UE110disconnects from a base station within the EPC160network and moves to a base station within the 5G core network150).

Example Devices

FIG.2illustrates an example device diagram200for devices that can implement various aspects of a UE context transfer over RAN paging. The example device diagram200includes the multiple UE110and the base stations120. The multiple UE110and the base stations120may include additional functions and interfaces that are omitted fromFIG.2for the sake of clarity. The UE110includes antennas202, a radio frequency front end204(RF front end204), an LTE transceiver206, and a 5G NR transceiver208for communicating with base stations120in the 5G RAN141and/or the E-UTRAN142. The RF front end204of the UE110can couple or connect the LTE transceiver206, and the 5G NR transceiver208to the antennas202to facilitate various types of wireless communication. The antennas202of the UE110may include an array of multiple antennas that are configured similar to or differently from each other. The antennas202and the RF front end204can be tuned to, and/or be tunable to, one or more frequency bands defined by the 3GPP LTE and 5G NR communication standards and implemented by the LTE transceiver206, and/or the 5G NR transceiver208. Additionally, the antennas202, the RF front end204, the LTE transceiver206, and/or the 5G NR transceiver208may be configured to support beamforming for the transmission and reception of communications with the base stations120. By way of example and not limitation, the antennas202and the RF front end204can be implemented for operation in sub-gigahertz bands, sub-6 GHZ bands, and/or above 6 GHz bands that are defined by the 3GPP LTE and 5G NR communication standards.

The UE110also includes processor(s)210and computer-readable storage media212(CRM212). The processor210may be a single core processor or a multiple-core processor composed of a variety of materials, such as silicon, polysilicon, high-K dielectric, copper, and so on. The computer-readable storage media described herein excludes propagating signals. CRM212may include any suitable memory or storage device such as random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), or Flash memory.

CRM212also includes code of a connection manager216. Alternately or additionally, the connection manager216may be implemented in whole or in part as hardware logic or circuitry integrated with or separate from other components of the UE110. In at least some aspects, the executing the code of the connection manager216configures the UE110to receive paging messages from the base station120and, in response, transmit messages to the base station120that indicate the UE110wishes to enter an engaged mode with the base station120. In some instances, the messages may include a message authentication code identifier (MAC-I) that might be used by the base station120as part of a verification process.

The device diagram for the base stations120, shown inFIG.2, includes a single network node (e.g., a gNode B). The functionality of the base stations120may be distributed across multiple network nodes or devices and may be distributed in any fashion suitable to perform the functions described herein. The base stations120include antennas252, a radio frequency front end254(RF front end254), one or more LTE transceivers256, and/or one or more 5G NR transceivers258for communicating with the UE110. The RF front end254of the base stations120can couple or connect the LTE transceivers256and the 5G NR transceivers258to the antennas252to facilitate various types of wireless communication. The antennas252of the base stations120may include an array of multiple antennas that are configured similar to or differently from each other. The antennas252and the RF front end254can be tuned to, and/or be tunable to, one or more frequency bands defined by the 3GPP LTE and 5G NR communication standards, and implemented by the LTE transceivers256, and/or the 5G NR transceivers258. Additionally, the antennas252, the RF front end254, the LTE transceivers256, and/or the 5G NR transceivers258may be configured to support beamforming, such as Massive-MIMO, for the transmission and reception of communications with the UE110.

The base stations120also include processor(s)260and computer-readable storage media262(CRM262). The processor260may be a single-core processor or a multiple-core processor composed of a variety of materials, such as silicon, polysilicon, high-K dielectric, copper, and so on. CRM262may include any suitable memory or storage device such as random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), or Flash memory.

The CRM262also includes a base station manager264. Alternately or additionally, the base station manager264may be implemented in whole or in part as hardware logic or circuitry integrated with or separate from other components of the base stations120. In at least some aspects, the base station manager264configures the LTE transceivers256and the 5G NR transceivers258for communication with the UE110, as well as communication with a core network.

The base station manager264includes code of a context manager266. In at least some aspects, the executing the code of the context manager266configures the base station120to receive, from another base station, a paging message that includes user equipment context information. Executing the code of the context manager266may also cause the base station120to verify a message received from the UE110by comparing a resume MAC-I, included in the received message, to a calculated MAC-I. Executing the code of the context manager266may also cause the base station120to transmit a message that enables the UE110to enter an engaged mode with the base station120in accordance with the user equipment context information.

The base stations120include an inter-base station interface268, such as an Xn and/or X2 interface, which the base station manager264configures to exchange user-plane and control-plane data between another base station120, to manage the communication of the base stations120with the UE110. The base stations120include a core network interface270that the base station manager264configures to exchange user-plane and control-plane data with core network functions and entities. In an instance where the other base station transmitting the paging message (that includes the context information) is a same generation as the base station120, the inter-base station interface268may receive the paging message. In an instance where the other base station is a different generation than the base station120, the core network interface270may receive the paging message.

FIG.3illustrates example user equipment states300between a user equipment (e.g., the UE110) and a base station (e.g., the base station120). Generally, a wireless network operator provides telecommunication services to user equipment through a wireless network. To communicate wirelessly with the network, a user equipment110utilizes a radio resource control (RRC) procedure to establish a connection to the network via a cell (e.g., the base station, a serving cell). Upon establishing the connection to the network via the base stations120, the user equipment110enters a connected mode (e.g., RRC-connected mode, RRC_CONNECTED state, NR-RRC CONNECTED state, or E-UTRA RRC CONNECTED state).

The user equipment110operates according to different resource control states310. Different situations may occur that cause the user equipment110to transition between different resource control states310as determined by the radio access technology. Example resource control states310illustrated inFIG.3include a connected mode312, an idle mode314, and an inactive mode316. A user equipment110is either in the connected mode312or in the inactive mode316when an RRC connection is active. If an RRC connection is not active, then the user equipment110is in the idle mode314.

In establishing the RRC connection, the user equipment110may transition from the idle mode314to the connected mode312. After establishing the connection, the user equipment110may transition (e.g., upon connection inactivation) from the connected mode312to an inactive mode316(e.g., RRC-inactive mode, RRC INACTIVE state, NR-RRC INACTIVE state) and the user equipment110may transition (e.g., via an RRC connection resume procedure) from the inactive mode316to the connected mode312. After establishing the connection, the user equipment110may transition between the connected mode312to an idle mode314(e.g., RRC-idle mode, RRC IDLE state, NR-RRC IDLE state, E-UTRA RRC IDLE state), for instance upon the network releasing the RRC connection. Further, the user equipment110may transition between the inactive mode316and the idle mode314.

The user equipment110may be in an engaged mode322or may be in a disengaged mode324. As used herein, an engaged mode322is a connected mode (e.g., connected mode312) and a disengaged mode324is an idle, disconnected, connected-but-inactive, or connected-but-dormant mode (e.g., idle mode314, inactive mode316). In some cases, in the disengaged mode324, the user equipment110may still be registered at a Non-Access Stratum (NAS) layer with an active radio bearer (e.g., in inactive mode316).

Each of the different resource control states310may have different quantities or types of resources available, which may affect power consumption within the user equipment110. In general, the connected mode312represents the user equipment110actively connected to (engaged with) the base stations120. In the inactive mode316, the user equipment110suspends connectivity with the base station120and retains information that enables connectivity with the base station120to be quickly re-established. In the idle mode314the user equipment110releases the connection with the base stations120.

Some of the resource control states310may be limited to certain radio access technologies. For example, the inactive mode316may be supported in LTE Release 15 (eLTE) and 5G NR, but not in 3G or previous generations of 4G standards. Other resource control states may be common or compatible across multiple radio access technologies, such as the connected mode312or the idle mode314.

Example Methods

FIG.4illustrates an example method400performed by a first of two base stations in accordance with aspects of techniques described herein. The method400may be performed by the base station121ofFIG.1, using elements ofFIG.1andFIG.2. Furthermore, and in the example method400, the base station (e.g., the base station121) may be a target base station.

At operation402, a first base station (e.g., the base station121) receives from a second base station (e.g., the base station123, a last-serving base station) a first message that includes a context. The context may be associated with a user equipment (e.g., the UE110) while the UE110was previously in an engaged mode with the second base station123. In some instances, the engaged mode may be a radio resource control (RRC) connected state. The first message may be a radio access network (RAN) paging message in accordance with a 5G NR wireless-communication protocol, such as an Xn RAN paging message.

At operation404, the first base station121transmits to the UE110a second message that includes a radio network temporary identifier (e.g., an I-RNTI) for identifying the context. The second message may be a radio resource control (RRC) paging message conforming with a 5G NR wireless-communication protocol.

At operation406, and in response to transmitting the second message, the first base station121receives from the UE110a third message that includes a resume message authentication code identifier (MAC-I).

At operation408the first base station121verifies the third message using the resume MAC-I. Verifying the third message may, in some instances, include verifying that the resume MAC-I is identical with a calculated MAC-I, where the calculated MAC-I is generated by the first base station121based on a set of parameters that the first base station121receives from the second base station123. The parameters may be received through the first message and comprise one or more parameters that are defined in a document that is used to support a wireless communication protocol. As an example, the document may correspond to 3GPP TS 33.501 and the parameters may correspond to a physical cell identifier (PCI), a cell radio network temporary identifier (C-RNTI), a resume constant, an NG-RAN key, (KgNB) or a Next Hop key (NH).

In another example instance of the operation408, verifying the third message may include the first base station121verifying that the resume MAC-I is identical to a calculated MAC-I generated by the second base station123. The calculated MAC-I may be received, by the first base station121and from the second base station123, through the first message.

In yet another example instance of the operation408, verifying the third message may include the first base station121verifying that the resume MAC-I is identical to a calculated MAC-I from a plurality of calculated MAC-I's generated by the second base station123. The calculated MAC-I's may be received, by the first base station121and from the second base station123, via the first message.

At operation410, the first base station121transmits, to the UE110, a fourth message that enables the UE110to resume the engaged mode with the first base station121in accordance with the context (e.g., the context received by the first base station121from the second base station123). The fourth message may be an RRCResume message. Resumption of the engaged mode with the first base station121may, for example, include the UE110entering a radio resource control (RRC) connected state (e.g., RRC_CONNECTED).

The example method400may include additional operations. For example, after the first base station121transmits to the UE110the fourth message that enables the UE110to resume the engaged mode, the first base station121may transmit to the second base station123a fifth message that includes a forwarding address indication to prevent a loss of user data that may be buffered or stored at the second base station123. The first base station121may also transmit, to a core network (e.g., the AMF152of the 5GC150) a sixth message that indicates a request to perform a path switch and receive, from the AMF152of the 5GC150, a seventh message that includes a response to the path switch request (e.g., the sixth message). The first base station121may also transmit to the second base station123an eighth message that includes a UE context release command, effectuating a release of resources supporting wireless communications between the second base station123and the UE110.

FIG.5illustrates an example method500performed by a user equipment in accordance with aspects of techniques described herein. The user equipment may be the UE110ofFIG.1and perform the method500using elements ofFIG.1andFIG.2.

At operation502, the UE110discontinues an engaged mode with a second base station (e.g., the base station123) to enter a disengaged mode. For example, discontinuing the engaged mode may cause the user equipment to enter a radio resource control (RRC) inactive state (e.g., RRC INACTIVE). Furthermore, entering the RRC INACTIVE state may be caused by the UE110receiving, from the second base station123, a message that includes a suspend configuration.

At operation504the UE110receives, from a first base station (e.g., the base station121), a first message that includes a radio network temporary identifier (I-RNTI) that identifies a context of the UE110while the UE110was in the engaged mode with the second base station123. The first message may be a radio resource control (RRC) paging message in accordance with a 5G NR wireless-communication protocol. At operation506, the UE110converts the I-RNTI to a resume message authentication code identifier (MAC-I).

At operation508, and in response to receiving the first message, the UE110transmits to the first base station121a second message that includes a includes the resume MAC-I. The second message, which may be an RRCResumeRequest message, causes the first base station121to verify the second message based on the resume MAC-I.

At operation510, the UE110receives, from the first base station121, a third message. In an instance where the second message that includes the resume MCA-I is verified by the first base station121is verified, the third message causes the UE110to resume the engaged mode with the first base station121in accordance with the context identified at operation504. For example, the third message may be an RRCResume message and the engaged mode may include the UE110entering a radio resource control (RRC) connected state (e.g., RRC_CONNECTED).

In an instance where the second message that includes the resume MAC-I is not verified by the first base station121, the third message may cause the UE110to remain in the disengaged mode.

FIG.6illustrates an example method600performed by a base station in accordance with aspects of techniques described herein. The method600may be performed by the base station123ofFIG.1, using elements ofFIG.1andFIG.2. Furthermore, and in the example method600, the base station (e.g., the base station123) may be a last-serving base station.

At operation602, the base station123triggers transmission of a first message that includes a context of the UE110that was previously in an engaged mode with the base station123. In some instances, incoming downlink user plane data or downlink signaling from a core network (e.g., the 5GC150) may trigger the first message.

At operation604, the base station123transmits the first message to another base station (e.g., the base station121). The first message may include the context and cause the other base station121to transmit, to the UE110, a second message that includes a radio network temporary identifier that identifies the context (e.g., an I-RNTI). In some instances at operation604, the first message may be transmitted using radio access network (RAN) paging.

Signaling and Control Transactions

FIG.7illustrates details700of example signaling and control transactions associated with a UE context transfer over RAN paging in accordance with aspects of techniques described herein. The signaling and control transactions may occur in accordance with data frames or subframes of wireless communication protocols such as 5G NR wireless communication protocols. Furthermore, the example signaling and control diagrams may occur amongst the UE110, the base station121, the base station123, and the 5G Core Network150ofFIG.1.

After the UE110enters a disengaged mode at705(e.g., RCC_INACTIVE), the base station123(e.g., a last-serving base station for the UE110) triggers at710a RAN paging message to the base station121(a target base station). In some instances, incoming downlink user plane data or downlink signaling from a core network (e.g., the 5GC150) may trigger the RAN paging message.

At715, the base station123transmits a first message (e.g., the RAN paging message) to the base station121. The RAN paging message includes context associated with the UE110while the UE110was in an engaged state with the base station123. In some instances, the RAN paging message may include one or more calculated message authentication code identifiers (MAC-I's) generated by the base station123.

At720, the base station121transmits a second message (e.g., an RRC paging message) to the UE110. The second message includes a radio network temporary identifier that identifies the context (e.g., an I-RNTI that identifies the context included in the message at715).

At725, the UE110transmits a third message (e.g., an RRC resume request message) to the base station121. The RRC resume request message includes a resume message authentication code identifier (MAC-I). After the base station121verifies the RRC resume request message at730, and at735, the base station121transmits a fourth message (e.g., an RRC resume message) to the UE110.

Additional signaling and transactions occur as part of the UE context transfer over RAN paging. At740, the base station121transmits a forwarding address indication to the base station123and at745, the base station121transmits a switch request message to the 5G core network150(e.g., the AMF152). At750, the 5G core network150transmits a switch response message to the base station121and, in response at755, the base station121transmits a context release message to the base station123. The UE110then enters an engaged mode with the base station121at760. An example of the engaged mode includes a connected mode corresponding to an RRC_CONNECTED state.

The described signaling and control transactions are by way of example only, and are not constrained by the sequence or order of presentation or constrained to 3GPP or 5G wireless communications only. Furthermore, in certain aspects, additional signaling and control transactions may augment or replace the described signaling and control transactions.

The following paragraphs recite several examples:

Example 1: A method performed by a first of two base stations comprising: receiving, by the first base station and from a second base station, a first message that includes a context of a user equipment that was previously in an engaged mode with the second base station; transmitting, by the first base station in response to receiving the first message and to the user equipment, a second message that includes a radio network temporary identifier that identifies the context; receiving, by the first base station from the user equipment, a third message that includes a resume message authentication code identifier; verifying, by the first base station, the third message by comparing the resume message authentication code identifier received in the third message with a calculated message authentication code identifier; and transmitting, to the user equipment, a fourth message that enables the user equipment to resume the engaged mode with the first base station in accordance with the context.

Example 2: The method as recited in example 1 wherein: receiving the first message includes receiving a set of parameters that comprise one or more of a physical cell identifier, a cell radio network temporary identifier, a resume constant, or a key; and verifying the third message includes verifying that the resume message authentication code identifier is identical to a calculated message authentication code identifier generated by the first base station based on the set of parameters.

Example 3: The method as recited in example 1 or example 2, wherein: receiving the first message includes receiving a calculated message authentication code identifier generated by the second base station; and verifying the third message includes verifying that the resume message authentication code identifier is identical to the calculated message authentication code identifier.

Example 4: The method as recited in any of examples 1 to 3, wherein: receiving the first message includes receiving a plurality of calculated message authentication code identifiers, each calculated authentication code identifier of the plurality of calculated message authentication code identifiers generated by the second base station; and verifying the third message includes verifying that the resume authentication code identifier is identical to a calculated message authentication code identifier from the plurality of calculated message authentication code identifiers.

Example 5: The method as recited in any of examples 1 to 4, further comprising transmitting, by the first base station to the second base station, a fifth message that indicates forwarding address information.

Example 6: The method as recited in any of examples 1 to 5, further comprising: transmitting, by the first base station and to a core network, a sixth message that indicates a request to perform a path switch; and receiving, from the core network, a seventh message that includes a response to the sixth message.

Example 7: The method as recited in any of examples 1 to 6, further comprising transmitting, by the first base station and to the second base station, an eighth message that includes a context release command, the context release command effectuating a release of resources supporting wireless communications between the second base station and the user equipment.

Example 8: A method performed by a user equipment, the method comprising: discontinuing, by the user equipment, an engaged mode with a second base station to enter a disengaged mode; receiving, from a first base station, a first message that includes a radio network temporary identifier that identifies a context associated with the user equipment while the user equipment was in the engaged mode with the second base station; converting, by the user equipment, the radio network temporary identifier to a resume message authentication code identifier; transmitting, by the user equipment to the first base station in response to receiving the first message, a second message that includes the resume message authentication code identifier; and receiving, by the user equipment from the first base station, a third message from the first base station, wherein the third message causes the user equipment to: resume, with the first base station, the engaged mode in accordance with the context; or remain in the disengaged mode.

Example 9: The method as recited in example 8, wherein, prior to discontinuing the engaged mode, the user equipment receives, from the second base station, a radio resource control release message that includes a suspend configuration.

Example 10: The method as recited in example 8 or example 9, wherein discontinuing the engaged mode causes the user equipment to enter a radio resource control inactive state

Example 11: The method as recited by any of examples 8 to 10, wherein the second base station is a last-serving base station.

Example 12: A method performed by a base station, the method comprising: triggering, by the base station, transmission of a first message that includes a context of a user equipment that was previously in an engaged mode with the base station; and transmitting, by the base station and to another base station, a second message that: includes the context; and causes the other base station to transmit, to the user equipment, a second message that includes a radio network temporary identifier that identifies the context.

Example 13: The method as recited by example 12, wherein triggering the transmission of the first message is based on incoming downlink user plane data or downlink signaling from a core network.

Example 14: The method as recited by example 12, wherein transmitting the first message includes transmitting the first message using radio access network paging.

Example 15: A first base station comprising: a wireless transceiver; and a processor and computer-readable storage media comprising instructions to implement a context manager application, the context manager application configured to direct the first base station to perform any method as recited in examples 1 to 7.