Patent Description:
Efforts are currently underway to define next generation wireless communication networks that provide greater deployment flexibility, support for a multitude of devices and services and different technologies for efficient bandwidth utilization. For better bandwidth utilizations, various techniques, including new ways to provide higher quality of service, are being discussed. <CIT> relates to a method and apparatus for performing inter-MeNB handover without SeNB change in a wireless communication system.

This document describes technologies, among other things, for providing master and secondary base station support to user devices during movement from one cell to another.

A first aspect of the invention comprises a method for wireless communications as set forth in claim <NUM>. The method includes.

In some embodiments, the first core network and the second core network are the same core network. In the claimed invention, the first core network and the second core network are different core networks.

In some embodiments, the first network element and the third network element operate using a first radio access technology (RAT). The first RAT may be a fourth generation (<NUM>) RAT technology. The first RAT may also be a fifth generation (<NUM>) RAT technology.

In some embodiments, the second network element and the fourth network element operating using a second RAT. In the claimed invention, the first RAT and the second RAT correspond to different protocol standards. In some implementations, the first RAT and the second RAT correspond to a same protocol standard.

In some embodiments, the configuration information of the second network element is communicated using a data structure from one of the following: a container, a container and multiple explicit information elements, multiple containers, or multiple containers and multiple explicit information elements.

A second aspect of the invention comprises a wireless communication apparatus as set forth in claim <NUM>.

A third aspect of the invention comprises a non-transitory computer-readable program medium as set forth in claim <NUM>.

Some preferred embodiments are defined in the dependent claims.

The details of one or more implementations are set forth in the accompanying attachments, the drawings, and the description below.

The following abbreviations are used in the present document.

Cellular mobile communication systems have evolved over the years. After several decades of development, the current fourth generation (<NUM>, 4th Generation) mobile communication systems have a wide variety of applications. To meet the increased demand for bandwidth, the fifth generation (<NUM>, 5th Generation) mobile communication architecture is being developed to provide higher throughput, lower latency, and greater user volume of diversified business services. For <NUM> systems, such as the Long Term Evolution (LTE) systems, the base station is referred to as eNB (E-UTRAN NodeB), the core network is referred to as EPC (Evolved Packet Core). In the <NUM> architecture, the base station is referred to as gNB (Global NodeB), and the core network is referred to as 5GC (<NUM> Generation Core).

In order to ensure that, in the future, operators can smoothly evolve from <NUM> mobile communication systems to <NUM> mobile communication systems in network deployments, in the initial stage of <NUM> research, a <NUM>/<NUM> dual connectivity solution is proposed, which uses both <NUM> and <NUM> base stations (dual connectivity, also referred to as DC). In dual connectivity communication, the core network types for the connections and the types of master and secondary base stations are different. The possible combinations can be divided into a variety of <NUM>/<NUM> dual-link networking scenarios, such as:.

Furthermore, in <NUM> mobile communication systems, in order to ensure that <NUM> users may receive high bandwidth connectivity, <NUM> base stations within a <NUM> core network are used for dual connectivity(i.e., both the master base station and the secondary base station are <NUM> base stations).

In the present document, the primary base station is collectively referred to as MN, Master Node (MN), or Master Cell Group (MCG). The secondary base station is collectively referred to as Secondary node (SN), or Secondary Cell Group (SCG).

Due to the mobility of a user device or a terminal, in the above-mentioned dual connectivity scenarios, the terminal may perform the site update once the terminal is moved out of the coverage of the current master or secondary base stations. In the traditional technology LTE systems, the following ways of changing the master or secondary base stations are supported:.

In the dual connectivity scenarios in the LTE systems, when the secondary base station is triggered to change (e.g., change of SeNB), the process can only be initiated by the master base station. <FIG> shows an example of a signaling flow for a change of a secondary base station in the LTE systems.

At <NUM>, the master base station <NUM> triggers a change of the secondary base station.

At <NUM>, the master base station <NUM> sends a request to a target secondary base station <NUM> for the change. The request may include configuration information of the master base station <NUM> and the source secondary base station <NUM>. The request may also include service related information for the target secondary base station <NUM>.

At <NUM>, the target secondary base station <NUM> receives the request and establishes corresponding configuration in the target secondary base station <NUM> based on the received request. The target secondary base station <NUM> then compares the configuration information between the source secondary base station <NUM> and the target secondary base station <NUM>. The target secondary base station <NUM> generates supplemental configuration information, which represents the delta between the configuration information of the source secondary base station <NUM> and the configuration information of the target secondary base station <NUM>, based on the comparison.

At <NUM>, the target secondary base station <NUM> transmits a response to the master base station <NUM>. The response may include the generated supplemental configuration information.

At <NUM>, the master base station <NUM> then sends a release request to the source secondary base station <NUM>.

At <NUM>, the master base station <NUM> transmits an air interface configuration message to the terminal with the supplemental configuration information of the target secondary base station <NUM> and other configuration information of the source master base station <NUM>.

At <NUM>, the terminal performs configuration based on the message from the master base station <NUM>, and transmits another message to confirm the configuration.

At <NUM>, the master base station <NUM> transmits a response to the target secondary base station <NUM> to notify that the configuration has completed.

Unlike the <NUM> dual connectivity and the <NUM>/<NUM> dual connectivity, in the dual connectivity of the LTE systems, the master base station always stores the latest wireless configuration information of the secondary base station because the air interface configuration can only be performed by the master base station. In order to obtain the supplemental configuration of the wireless parameters of the terminal, the request sent from the master base station to the new target secondary base station (i.e., SN addition request) can carry all the wireless configuration information of the current secondary base station (i.e., the source secondary base station) to assist the target secondary station adjust its configuration, so as to avoid reset and/or re-establishment of the user plane, MAC, and other relevant information and to avoid packet loss to ensure good user experiences.

One technical problem in the traditional LTE systems with dual connectivity is that such a system does not support simultaneous changing of the master base station and the secondary base station. Due to this limitation, when the master base station changes, the secondary base station remains unchanged. In order to have a different secondary base station, a terminal needs to first delete the old secondary base station, and then triggers an addition of a new secondary base station independently. Therefore, for <NUM> dual connectivity or <NUM>/<NUM> dual connectivity, a two-step process is needed when the master and secondary base stations need to change at the same time: (<NUM>) to delete the old secondary base station, and (<NUM>) to add the new secondary base station. This two-step process may adversely affect user data throughput and user experience during mobility.

Furthermore, the current LTE technology does not provide a solution for transmitting configuration information of the old secondary base station (i.e., source) to the new secondary base station (i.e., target), especially for the <NUM>/<NUM> dual connectivity scenarios. Since the wireless base stations belong to different mobile communication systems in the <NUM>/<NUM> dual connectivity scenarios, there are differences between the air interface specifications. Moreover, in <NUM>/<NUM> dual connectivity, the mater base station and the secondary base station belong to different radio access technology, which cannot comprehend each other's code logic, and may have separate air interface configuration or reconfiguration mechanism, and the partial configuration or reconfiguration process triggered by the secondary base station is invisible to the master base station. Therefore, the master base station cannot obtain the complete configuration information from the secondary base station. During simultaneous change of the master and secondary base stations, the new secondary base station cannot obtain the configuration information of the old secondary base station. The new secondary base station thus cannot support the supplemental configuration information for the terminal. A full configuration of the air interface may be required, which may result in user data packet loss and thereby affects user experiences.

The present document provides techniques that can be applied for a dual connectivity in which the terminal is connected to the master base station and the secondary base station at the same time. When a terminal switches its master and secondary base stations, both base stations can be switched at the same time (also referred to as Inter-Master Node handover with Secondary Node change). That is, the terminal switches from a source dual-link master and secondary base stations to a target dual-link master and secondary base stations.

In the description below, the source master base station is defined as a first network element, the source secondary base station is defined as a second network element, the target master base station is defined as a third network element, the target secondary base station is defined as a fourth network element, and the core network is defined as the fifth network element. <FIG> shows a schematic diagram of an exemplary configuration of core networks and network elements.

The techniques provide a method and an apparatus for configuring information between the source and target dual-link master and secondary base stations to solve the problem that the target secondary base station cannot obtain the complete configuration information of the source secondary base station.

<FIG> shows an example of a signaling flow of a handover of a terminal from a first network element to a third network element with a change from a second network element to a fourth network element. In <FIG>, the terminal is connected to the first network element <NUM> and the second network element <NUM>. The first network element <NUM> first obtains relevant information of the second network element <NUM>. The first network element <NUM> may obtain the relevant information by sending a message to the second network element <NUM> to request for such information and receiving a response from the second network element <NUM> that includes the relevant information. In some embodiments, the second network element <NUM> may send the information to the first network element when the information changes. The relevant information of the second network element <NUM> may be in a data structure one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

In the claimed invention, the information comprising the properties of the source secondary network element is comprised in at least one container and explicit information elements.

A container can be a transparent container, such as a Source To Target Transparent Container or a Target to Source Transparent Container used in current LTE systems. Each container may include multiple information elements for parameter configurations. The use of container(s) ensures that only the target node can decode the information included in the container. The use of explicit information element(s), on the other hand, allow both the target node and the intermediate relay node(s) to decode and/or modify the information included therein. The data structure may also include configuration information, some or all, of the first network element.

The relevant information of the second network element <NUM> includes but is not limited to the configuration information of the primary cell and the secondary cell(s) under the second network element <NUM> and relevant measurement information provided by the second network element <NUM>. In some embodiments, a secondary cell under the second network element <NUM> is a secondary cell under the second base station in carrier aggregation (CA) scenarios. In some implementations, the number of the secondary cells is greater than or equal to <NUM>.

In some embodiments, the configuration information of the primary cell under the second network element <NUM> includes at least one of the following: carrier configuration information, user plane configuration information, physical resource common configuration information, physical resource specific configuration information, MAC layer configuration, measurement configuration, and measurement results.

The configuration information of the secondary cell under the second network element <NUM> includes at least one of the following information: carrier configuration information, user plane configuration information, physical resource common configuration information, physical resource specific configuration information, MAC layer configuration information, measurement configuration, and measurement results.

In the claimed invention, the relevannt information comprises configuration information of a primary cell and at least one possible secondary cell under the source secondary network element, wherein the number of the secondary cells is greater than or equal to <NUM>, the configuration information comprising user plane configuration information, physical resource configuration information, and Medium Access Control, MAC, layer configuration of at least one cell under the source secondary network element, and the information further comprises measurement information provided by the source secondary network element.

At <NUM>, the first network element <NUM> initiates the terminal to hand over to the third network element <NUM>. The first network element <NUM> sends, at <NUM>, a request to the third network element <NUM> and transmits the relevant information of the second network element <NUM> together with the relevant information of the first network element <NUM> to the third network element <NUM>. The first network element <NUM> may transmit the relevant information directly to the third network element <NUM>. In some embodiments, the first network element 251transmits the relevant information to the fifth network element <NUM> first, and then the information is indirectly transmitted from the fifth network element <NUM> to the third network element <NUM>. The relevant information of the second network element <NUM> and the relevant information of the first network element <NUM> may be in a data structure in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements. The data structure may also include at least some configuration information of the first network element.

The third network element <NUM> obtains the relevant information of the second network element <NUM> and the relevant information of the first network element <NUM> and determines, at <NUM>, whether to change the second network element <NUM> to the fourth network element <NUM>. If the third network element <NUM> determines so, it transmits, at <NUM>, the relevant information of the second network element <NUM> to the fourth network element <NUM>. The relevant information of the second network element may be in a data structure in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements. The data structure may also include at least some configuration information of the first network element.

In some embodiments, the third network element <NUM> may determine whether or not to perform the change based on the obtained measurement information. The measurement information obtained by the third network element <NUM> may include: the measurement information provided by the first network element <NUM>, and/or the measurement information provided by the second network element <NUM>. The received measurement information may be in a data structure one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements. The data structure may also include at least some configuration of the first network element.

In some embodiments, the third network element <NUM> obtains the measurement information provided by the first network element <NUM> by direct transmission of the information from the first network element <NUM> to the third network element <NUM>. Alternatively, the information can be transmitted to the fifth network element <NUM> from the first network element <NUM>, and the information is indirectly transmitted to the third network element <NUM> by the fifth network element <NUM>.

In some embodiments, the third network element <NUM> obtains the measurement information provided by the second network element <NUM> using the following steps: (<NUM>) the first network element <NUM> obtains the relevant information of the second network element <NUM>, and (<NUM>) the first network element <NUM> transmits the information directly to the third network element <NUM>. Alternatively, the third network element <NUM> may obtain the measurement information using the following steps: (<NUM>) the first network element <NUM> obtains the relevant information of the second network element <NUM>, (<NUM>) the first network element <NUM> transmits the information to the fifth network element <NUM>, and (<NUM>) the fifth network element <NUM> indirectly transmits the information to the third network element <NUM>. In each information transmission, the measurement information are may be in a data structure one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements. The data structure may also include at least some configuration information of the first network element.

In some embodiments, the third network element <NUM> may pass the obtained relevant information of the second network element <NUM> and/or measurement information to the fourth network element <NUM> for the fourth network element <NUM> to perform primary cell selection. The relevant information and measurement information may be in a data structure in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements. Furthermore, after receiving the relevant information of the second network element <NUM>, the fourth network element <NUM> may generate supplemental configuration information based on the received information, the radio resource configuration information, the measurement configuration information, etc. The fourth network element <NUM> can transmit, at <NUM>, the supplemental configuration information to the third network element <NUM>. The third network element <NUM> may further transmit, at <NUM>, the supplemental configuration information of the fourth network element <NUM> along with other types of information that the third network element <NUM> has generated to the first network element <NUM>. The data structure may also include at least some or all configuration information of the first network element.

In some embodiments, the third network element <NUM> may transmit directly to the first network element <NUM>. In some implementations, the third network element <NUM> transmits the information to the fifth network element <NUM>, and the information is indirectly transmitted to the first network element <NUM> by the fifth network element <NUM>.

At <NUM>, the first network element <NUM> sends a release request to the second network element <NUM>.

At <NUM>, the first network element <NUM> transmits an air interface configuration message to the terminal to forward the relevant configuration information to the terminal.

At <NUM>, the terminal performs configuration based on the message from the first network element <NUM>, and transmits another message to the third network element <NUM> to establish the connection.

At <NUM>, the third network element <NUM> sends a confirmation message to the fourth network element <NUM> to confirm the new connection.

The above mentioned methods are further explained in the following embodiments.

<FIG> shows an exemplary change of master base stations that is triggered through a direct interface between a source master base station and a target master base station.

Step <NUM>: The source master base station obtains, at <NUM>, the configuration information of the source secondary base station. The source master base station can obtain the information by sending a message to the source secondary base station. Alternatively, the source secondary base station may send the information to the source master base station when its information changes. The obtained information of the source secondary base station may be in a data structure in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

Step <NUM>: The source master base station determines, at <NUM>, to trigger a change of base stations. The source master base station transmits, at <NUM>, a change request to the target master base station. The change request may include the configuration information of the source master base station. The change request may also include the configuration information of the source secondary base station obtained previously.

In some embodiments, the message may be a handover request message. The information of the source base station and the information of the source secondary base station may be in a data structure one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements. The configuration information of the secondary base stations includes configuration information of the primary cell (PSCell) and the secondary cell (SCell) under the secondary base station.

In some embodiments, the secondary cell of a secondary base station is a secondary cell under the Carrier Aggregation (CA) scenario on the secondary base station. The number of the secondary cells is equal to or greater than <NUM>.

In some embodiments, the configuration information of the primary cell includes one or more of the following: carrier configuration information, user plane configuration information, physical resource common configuration information, physical resource specific configuration information, MAC layer configuration information, measurement configuration information, and measurement results.

In some embodiments, the configuration information of the secondary cell includes one or more of the following: carrier configuration information, user plane configuration information, physical resource common configuration information, physical resource specific configuration information, MAC layer configuration information, measurement configuration information, and measurement results.

Step <NUM>: After the target master base station receives the configuration information, it determines, at <NUM>, whether a change of the secondary base station is necessary. If the target master base station determines so, it sends, at <NUM>, a request to a target secondary base station. The request may include the configuration information of target master node. The request may also include the service information and the configuration information of the source secondary base station.

In some embodiments, the request sent by the target master base station is an SN addition request message. In some implementations, the configuration information of target master node and the configuration information of the source secondary base station may be in a data structure in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

Step <NUM>: After receiving the request from the target master base station, the target secondary base station performs, at <NUM>, resource allocations based on the service information in the message. The target secondary base station may compare the configuration information between the target secondary base station and the source secondary base station to generate supplemental configuration information for the target secondary base station.

Step <NUM>: The target secondary base station transmits, at <NUM>, the supplemental configuration information to the target master base station via a response message, indicating that resource allocations are successful for the target secondary base station.

In some embodiments, the response message is an SN addition request acknowledge message. In some implementations, the supplemental configuration information may be in a data structure in one of the following forms: one container, or one container and explicit information elements, or more than one container, or more than one container and explicit information elements.

Step <NUM>: After receiving the response message, the target master base station transmits, at <NUM>, the configuration information of the target master base station and/or the supplemental configuration information of the target secondary base station to the source master base station via a response message.

In some embodiments, the response message may be a handover request acknowledge message. The configuration information of the target master base station and/or the supplemental configuration information of the target secondary base station may be in one of the following forms in the response message: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

Step <NUM>: After receiving the response message, the source master base station sends, at <NUM>, a release request message to the source secondary base station to inform the source secondary base station to release resources.

Step <NUM>: The source master base station also transmits, at <NUM>, an air interface configuration message to the terminal to forward the relevant configuration information to the terminal.

Step <NUM>: After the terminal completes the air interface configuration, the random access procedure of the target master station and the target secondary base station is started and the air interface configuration success message is sent, at <NUM>, to the target master base station.

Step <NUM>: After receiving the response at the target master base station at <NUM>, the target master base station notifies the target secondary base station of the new connection.

Step <NUM>: The network performs user data back-propagation and corresponding core-side upper-layer switching process.

<FIG> shows an exemplary change of master base station that is triggered through an indirect interface. The example is applicable when there is no direct interface between the source master base station and the target master base station, or when the core network type changes.

Step <NUM>: The source master base station obtains, at <NUM>, the configuration information of the source secondary base station. The source master base station can obtain the information by sending a message to the source secondary base station. Alternatively, the source secondary base station may send the information to the source master base station when its information changes. The obtained information of the source secondary base station may be in a data structure in one of the following forms: one container, or one container and explicit information elements, or more than one containers, or more than one containers and explicit information elements. The data structure may also include configuration information, some or all, of the source master base station.

Step <NUM>: The source master base station determines, at <NUM>, to trigger a change of base stations. The source master base station transmits, at <NUM>, a change request to the core network. The change request may include the configuration information of the source master base station. The change request may also include the configuration information of the source target base station obtained in Step <NUM>.

In some embodiments, the message may be a handover required message. The information of the source base station and the information of the source secondary base station may be in a data structure in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements. The configuration information of the secondary base stations includes configuration information of the primary cell (PSCell) and the secondary cell (SCell) under the secondary base stations.

In some embodiments, the secondary cell of the secondary base station is a secondary cell under the Carrier Aggregation (CA) scenario on the secondary base station. The number of the secondary cells is equal to or greater than <NUM>.

Step <NUM>: After the core network receives the above-mentioned message and configuration information, the core network transmits, at <NUM>, a message to the target master base station based on an identification of the target master base station included in the message. The message may also include service information, configuration information of the source master base station, and configuration information of the source secondary base station.

In some embodiments, the message may be a handover request message. In some implementations, the information of the source base station and the information of the source secondary base station may be in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

Step <NUM>: After receiving the message and the configuration information from the core network, the target master base station determines, at <NUM>, whether it is necessary to change the secondary base station. If the target master base station determines so, it sends, at <NUM>, a request to a target secondary base station. The request may include the configuration information of target master node. The request may also include the service information and the configuration information of the source secondary base station.

In some embodiments, the request sent by the target master base station is an SN addition request message. In some implementations, the configuration information of target master node and the configuration information of the source secondary base station may be in a data structure in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements. The data structure may also include some or all configuration information of the source master base station.

Step <NUM>: The target secondary base station transmits, at <NUM>, the supplemental configuration information to the target master base station through a response message, indicating that resource allocations are successful for the target secondary base station.

In some embodiments, the response message is an SN addition request acknowledge message. In some implementations, the supplemental configuration information may be in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

Step <NUM>: After receiving the response message, the target master base station transmits, at <NUM>, the configuration information of the target base station and/or the supplemental configuration information of the target secondary base station to the core network via another response message.

In some embodiments, the response message may be a handover request acknowledge message. The configuration information of the target master base station and/or the supplemental configuration information of the target secondary base station may be in a data structure one of the following forms in the response message: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

Step <NUM>: After receiving the above message and configuration information, the core network transmits, at <NUM>, a response message to the source master base station. The response message may include the configuration information of the target master base station and/or the supplemental configuration information of the target secondary base station.

In some embodiments, the response message is a handover command message. The configuration information of the target base station and/or the supplemental configuration information of the target secondary base station may be in one of the following forms in the response message: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

Step <NUM>: After the terminal completes the air interface configuration, the random access procedure of the target master base station and the target secondary base station is started and the air interface configuration success message is sent, at <NUM>, to the target master base station.

<FIG> shows an exemplary change of master base stations with measurement information of transmissions.

Step <NUM>: The source master base station obtains, at <NUM>, the configuration information of the source secondary base station. The source master base station can obtain the information by sending a message to the source secondary base station. Alternatively, the source secondary base station may send the information to the source master base station when its information changes. The obtained information of the source secondary base station may be in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

Step <NUM>: The source master base station determines, at <NUM>, to trigger a change of base stations. The source master base station transmits, at <NUM>, a change request to the target master base station. The change request may include the configuration information of the source master base station. The change request may also include the configuration information of the source secondary base station obtained previously. The change request may further include measurement results sent from the terminal to the source master base station.

In some embodiments, the message may be a handover request message. The information of the source base station and the information of the source secondary base station, and the measurement information/results may be in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements. The configuration information of the secondary base stations includes configuration information of the primary cell (PSCell) and the secondary cell (SCell) under the secondary base stations.

Step <NUM>: After receiving the message and the configuration information, the target master base station determines, at <NUM>, whether it is necessary to change the secondary base station based on the measurement information and/or measurement results included in the message. If the target master base station determines so, it transmits, at <NUM>, a request to a target secondary base station. The request may include the configuration information of target master node, The request may also include service information and the configuration information of the source secondary base station. The request may also include measurement information and/or measurement results.

In some embodiments, the request sent by the target master base station is an SN addition request message. In some implementations, the configuration information of target master node, the configuration information of the source secondary base station and the measurement information and/or measurement results may be in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

Step <NUM>: After receiving the request from the target master base station, the target secondary base station selects, at <NUM>, the target primary cell based on the measurement information and/or measurement results, and performs resource allocations based on the service information included in the message. The target secondary base station may compare the configuration information between the target secondary base station and the source secondary base station to generate supplemental configuration information for the target secondary base station.

In some embodiments, the response message is an SN addition request acknowledge message. In some implementations, the configuration information may be in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

<FIG> shows another exemplary change of master base stations with measurement information of transmissions.

Step <NUM>: The source master base station obtains, at <NUM>, the configuration information and measurement information/results of the source secondary base station. The source master base station can obtain the information by sending a message to the source secondary base station. Alternatively, the source secondary base station may send the information to the source master base station when its information changes. The obtained configuration information and measurement information/results of the source secondary base station may be in one of the following forms: one container, one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

Step <NUM>: The source master base station determines, at <NUM>, to trigger a change of base stations. The source master base station transmits, at <NUM>, a change request to the target master base station. The change request may include the configuration information of the source master base station. The change request may also include the configuration information of the source secondary base station obtained previously. The change request may further include measurement information/results of the source secondary base station obtained previously. The change request may further include measurement results sent from the terminal to the source master base station.

In some embodiments, the message may be a handover request message. The information of the source base station and the information of the source secondary base station, and the measurement information/results may be in one of the following forms: one container, or one container and explicit information elements, multiple containers, or multiple containers and explicit information elements. The configuration information of the secondary base stations includes configuration information of the primary cell (PSCell) and the secondary cell (SCell) under the secondary base stations.

Step <NUM>: After receiving the message and the configuration information, the target master base station determines, at <NUM>, whether it is necessary to change the secondary base station based on the measurement information/results of the source secondary base station included in the message. If the target master base station determines so, it transmits, at <NUM>, a request to a target secondary base station. The request may include the configuration information of target master node. The request may also include service information and the configuration information of the source secondary base station. The request may also include measurement information and/or measurement results.

In some embodiments, the response message may be a handover request acknowledge message. The configuration information of the target master base station and/or the supplemental configuration information of the target secondary base station may be in one of the following forms in the response message: one container, or one container and explicit information elements, multiple containers, or multiple containers and explicit information elements.

In the various message exchange scenarios described in the present document, in some embodiments, when a source master base station sends configuration information to a target master base station, it may send information of the source master base station and information of the source secondary base station. In some embodiments, when the target master base station sends configuration information to the target secondary base station, that information may also include information of the target master base station, and information of the source secondary base station.

<FIG> is a flowchart representation of an exemplary method of wireless communication <NUM>. The method <NUM> includes, at <NUM>, providing connectivity between a first core network and a user device. The method <NUM> also includes, at <NUM>, communicating configuration information of a second network element.

In some embodiments, the method includes operating a first network element in a wireless communication network to provide connectivity between a first core network and a user device, wherein the wireless communication network includes a second network element that is configured to provide a secondary connectivity between the first core network and the user device; and communicating, by the first network element, in a handover to a third network element configured to provide connectivity with a second core network, configuration information of the second network element to the third network element.

<FIG> is another flowchart representation of an exemplary method of wireless communication <NUM>. The method <NUM> includes, at <NUM>, providing connectivity to a core network; at <NUM>, receiving information of a network element providing secondary connectivity; and at <NUM>, selectively deciding a network element that provides secondary connectivity.

In some embodiments, the method includes operating a first network element to provide connectivity to a first core network; receiving, when a user device is handed over from a second network element, information from the second network element providing connectivity to a second core network, wherein the information identifies properties of a third network element providing a secondary connectivity to the second core network; and selectively deciding, based on the information, a secondary connectivity network element between the third network element and a fourth network element for the first network element, wherein the fourth network element is configured to provide connectivity to the first core network.

<FIG> is a block diagram of an example of a wireless communication apparatus. The apparatus <NUM>, such as a base station or a wireless device (or a terminal), can include processor electronics <NUM> such as a microprocessor that implements one or more of the wireless techniques presented in this document. The apparatus <NUM> can include transceiver electronics <NUM> to send and/or receive wireless signals over one or more communication interfaces such as antenna <NUM>. The apparatus <NUM> can include other communication interfaces for transmitting and receiving data. The apparatus <NUM> can include one or more memories <NUM> configured to store information such as data and/or instructions. In some implementations, the processor electronics <NUM> can include at least a portion of the transceiver electronics <NUM>. In some embodiments, at least some of the disclosed techniques, modules or functions are implemented using the apparatus <NUM>.

<FIG> shows an example of wireless communications network where techniques in accordance with one or more embodiments of the present technology can be applied. A wireless communication system <NUM> can include one or more base stations (BSs) <NUM>, one or more wireless devices <NUM>, and a core network <NUM>. The base station <NUM> can provide wireless service to wireless devices <NUM> in one or more wireless sectors. In some implementations, a base station <NUM> includes directional antennas to produce two or more directional beams to provide wireless coverage in different sectors.

The core network <NUM> provides connectivity with other wireless communication systems and wired communication systems. The core network may include one or more service subscription databases to store information related to the subscribed wireless devices <NUM>. A first base station can provide wireless service based on a first radio access technology, whereas a second base station can provide wireless service based on a second radio access technology. The base stations may be co-located or may be separately installed in the field according to the deployment scenario.

It is thus evident that the techniques disclosed in the present document provide a method and an apparatus for configuring transmission for supporting simultaneous change of the master and secondary base stations. The target secondary base station is also capable of obtaining information regarding the source secondary base station without a full re-configuration of the air interface, thereby avoiding user data packet loss and maintaining good user experiences.

While this document contains many specifics, these should not be construed as limitations on the scope of the invention which is defined by the appended claims, but rather as descriptions of features specific to particular embodiments.

Claim 1:
A method for wireless communications, comprising:
operating a target master network element using a first radio access technology, RAT, in a wireless communication network to provide connectivity to a first core network;
receiving, by the target master network element in a handover of a user device from a source master network element that uses the first RAT and provides connectivity between the user device and a second, different core network, information from the source master network element,
wherein the information comprises properties of a source secondary network element using a second, different RAT that provides a secondary connectivity between the user device and the second core network,
wherein the information comprising the properties of the source secondary network element is comprised in at least one container and explicit information elements which are decodable by the target master network element and intermediate relay nodes,
wherein the information comprises configuration information of a primary cell and at least one possible secondary cell under the source secondary network element, wherein the number of the secondary cells is greater than or equal to <NUM>, the configuration information comprising user plane configuration information, physical resource configuration information, and Medium Access Control, MAC, layer configuration of at least one cell under the source secondary network element, the information further comprising measurement information provided by the source secondary network element; and
determining, by the target master network element, based on the information that identifies properties of the source secondary network element, whether to change a secondary connectivity network element from the source secondary network element to a target secondary network element that operates using the second RAT and provides connectivity to the first core network.