Patent Description:
Mobile data transmission and data services are constantly making progress. With the increasing penetration of such services, different access networks may coexist in parallel. Typically, in relation to mobile communication systems, an access network is represented by a radio access network (RAN) which is based on a certain radio access technology (RAT). While "radio" is a typical medium for mobile communication, other media are intended to be also covered by the principles taught herein. For example, Infrared or Bluetooth® or other media and/or wavelengths of radio are possible to represent the access network. As there has to be a (downward) compatibility between newly developed and pre-existing access networks and/or access networks technologies, terminals often have a capability to communicate based on one or more access networks technologies. Also, when a new access network is developed and launched, the network is not immediately available in the entire country of deployment, but its coverage may be limited to certain areas and be successively expanded over time.

The present invention will herein below be explained with reference to Long Term Evolution (LTE) as one example of a access network or radio access technology (LTE is also known as fourth generation <NUM> mobile communication) and its successor or
improvement which is currently being developed and referred to as <NUM> (fifth generation mobile communication) as a further access network or radio access technology, but also with reference to predecessors thereof. Though, principles set out herein below are applicable to other scenarios than explained, too. Typically, a mobile communication network consists of an access network establishing the physical transport of data (payload (user) data and control data) and a core network establishing the control functionality for the entire network and the interoperability of the network with other networks, e.g. via gateways. References to specific network entities or nodes and their names are intended as mere example only. Other network node names may apply in different scenarios while still accomplishing the same functionality. Also, the same functionality may be moved to another network entity. Therefore, the principles as taught herein below are not to be understood as being limited to the specific scenario referred to for explanation purposes.

For example, the Evolved Packet System (EPS) is the successor of General Packet Radio System (GPRS). It provides a new radio interface and new packet core network functions for broadband wireless data access. Such EPS core network functions are the Mobility Management Entity (MME), Packet Data Network Gateway (PDN-GW, P-GW) and Serving Gateway (S-GW).

<FIG> illustrates the Evolved Packet Core architecture as introduced and defined by 3GPP TS <NUM> v13.

The entities involved and interfaces there between are defined in that document and reference is made thereto for further details. Acronyms used in the Figure are listed at the end of this specification.

A common packet domain Core Network (CN) is used for both RANs, the Global System for Mobile Communication (GSM) Enhanced Radio Access Network (GERAN) and the Universal Terrestrial Radio Access Network (UTRAN). This common CN provides GPRS services.

It is envisioned that a <NUM> system will provide the new mobile, low-latency and ultra-reliable services, and some services like Vehicle-To-X (V2X) will be more efficiently provided by <NUM> system.

A reference to <NUM> architecture that is envisioned is depicted in <FIG>.

Acronyms used in the Figure are listed at the end of this specification.

In brief, a terminal such as a <NUM> NT (network terminal or user equipment) is provided with an internet protocol IP user network interface (IP UNI) and an Ethernet user network interface (ETH UNI) and may communicate via a Uu* interface with an Access Point (AP) in the mobile access network. The entire network has a mobile access part, a networks service part and an application part. Within each of those parts, there exists a control plane and a user (data) plane. The AP is located in both planes.

It is evident that interworking of <NUM> with the existing RAT technologies like LTE is needed.

<FIG> schematically illustrates possible inter RAT architecture following traditional concepts applied to a scenario with LTE and <NUM> mobile communication system.

Here, a terminal (user equipment, UE) capable of accessing to LTE network and <NUM> network is connected to a 5GAP being an access point of a <NUM> mobile communication system and to an evolved NodeB (eNB) being an access point of a <NUM>/<NUM> mobile communication system (LTE). The control plane (dotted lines) as well as the user plane (solid lines) of both mobile communication systems is handled by a control plane mobile gateway (cMGW) and a user plane gateway (uGW), respectively, via respective interfaces (S1*, S1-U, S1-C).

<NUM>rd Generation Partnership Project (3GPP) switched from the distributed architecture of wideband code division multiple access (WCDMA) to a flat architecture of LTE which allowed a reduction of the number of hardware boxes, a reduction of intermediate nodes, and a minimization of Access Stratum (AS) signaling during mobility.

The introduction of small cells with limited coverage compared to a large macro cell results in that the frequency of mobility events involving change of small cell base stations increases. That is, AS mobility events causes excessive signaling on the network, which consumes additional processing, additional signaling, and may cause service interruption during the mobility events.

However, it is expected that <NUM> is to have multiple flavors of small cells in centimeter wave and millimeter wave. Accordingly, the mentioned problem resulting from small cells is likely to be considerably increased.

Hence, there is a need to reduce signaling and to minimize service disruption during mobility events.

In particular, there is a need to provide for improvements in small cell mobility with dual/multi connectivity.

In this regard it is noted that dual connectivity means that a terminal moves between two radio access coverage areas having different RATs (here LTE and <NUM>), establishing simultaneous connections with both networks before seamlessly handing over.

Further, multi connectivity means that a terminal connects to two base stations of a RAT (here <NUM>) simultaneously, improving bit rate performance through multiple downlink streams, as well as signal strength and resilience.

Further prior art can be found in document <CIT>, disclosing a control method for supporting multiple connections in a mobile communication system and an apparatus for supporting multiple connections. In the method for supporting the multiple connections to be performed in first and second base stations, a first base station receives the measured results for multiple connections from a terminal, determines whether the plurality of connections are set on the basis of the measured results, transmits the information for setting the multiple connections to the second base station when setting the multiple results, and the second base station generates the control information for setting the multiple connections of the terminal on the basis of the information for setting the multiple connections received from the first base station. Thus, the multiple connections can be easily supported and the performance of the mobile communication system can be improved there through. Heretofore, function division between a macro cell and a small base station is defined. A local access mobile network may make more efficient traffic offloading and mobility control by enhancing signaling procedures between a macro base station and a small base station. For efficient traffic offloading, a protocol structure enhancement in a control-plane aspect and a user-plane aspect (or, a traffic data-plane) may be taken into account. Several radio protocol configurations of a local access mobile network are proposed. According to a first method, both control plane and user plane are configured in a macro base station, and only user plane is configured in a small eNB/cell. According to a second method, both control plane and user plane are configured in a macro base station, and only user plane and a part of control plane are configured in a small base station. According to a third method, both control plane and user plane are configured in a macro base station and a small base station.

Further prior art can be found in document <CIT>, disclosing systems and methods for providing a converged gateway (CGW) making routing decisions (e.g. segregation and/or aggregation of flows or traffic associated with data) for various interfaces and/or radio access technologies (RATs) that may be included in a LAN, device, and/or communication system. Dynamic flow management, load balancing, offloading, PDF context establishment, prioritization, detection of devices, and the like may also be provided and/or implemented in the CGW and may be used to route flows and/or traffic associated with data.

Further prior art can be found in document <CIT>, disclosing approaches for operating a wireless transmit/receive unit (WTRU) with multiple schedulers in a wireless system. The WTRU may exchange data with the network over more than one data path, such that each data path may use a radio interface connected to a different network node and each node may be associated with an independent scheduler. For example, a WTRU may establish a radio resource control (RRC) connection between the WTRU and a network. The RRC connection may establish a first radio interface between the WTRU and a first serving site of the network and a second radio interface between the WTRU and a second serving site of the network. The RRC connection may be established between the WTRU and an MeNB, and a control function may be established between the WTRU and an SCeNB. The WTRU may receive data from the network over the first radio interface or the second radio interface. A radio cloud network controller (RCNC) may be co-located with and/or implemented by the MeNB. The MeNB may determine what serving cell of an SCeNB may be suitable for offloading traffic to/from the WTRU. The MeNB may establish a connection to the selected SCeNB in order to provide WTRU context information to the SCeNB. The MeNB may receive a response message from the SCeNB that may include Access Stratum configuration (AS-configuration) information for one or more serving cells of the SCeNB.

Various exemplary embodiments of the present invention aim at addressing at least part of the above issues and/or problems and drawbacks.

Various aspects of exemplary embodiments of the present invention are set out in the appended claims.

The above mentioned objects are achieved by what is defined in the appended independent claims. Advantageous modifications thereof are set forth in the appended dependent claims.

Any one or more of the above aspects enables an efficient improvement on dual/multi connectivity, thereby optimizing intra- and inter-RAT mobility in that signaling during mobility events is reduced, and/or service disruption during handovers is minimized. These effects are achieved for both, intra-small cell and small cell-to-macro cell mobility. Thereby, at least part of the problems and drawbacks identified in relation to the prior art are solved.

By way of exemplary embodiments of the present invention, there is provided improvements in small cell mobility with dual/multi connectivity. More specifically, by way of exemplary embodiments of the present invention, there are provided measures and mechanisms for realizing improvements in small cell mobility with dual/multi connectivity.

Thus, improvement is achieved by methods, apparatuses and computer program products enabling/realizing improvements in small cell mobility with dual/multi connectivity.

In the following, the present invention will be described in greater detail by way of non- limiting examples with reference to the accompanying drawings, in which.

The present invention is described herein with reference to particular non-limiting examples and to what are presently considered to be conceivable embodiments of the present invention.

As mentioned before, it is to be noted that the following description of the present invention and its embodiments mainly refers to specifications being used as non-limiting examples for certain exemplary network configurations and deployments. Namely, the present invention and its embodiments are mainly described in relation to 3GPP specifications being used as non-limiting examples for certain exemplary network configurations and deployments. As such, the description of exemplary embodiments given herein specifically refers to terminology which is directly related thereto. Such terminology is only used in the context of the presented non-limiting examples, and does naturally not limit the invention in any way. Rather, any other communication or communication related system deployment, etc. may also be utilized as long as compliant with the features described herein.

According to exemplary embodiments of the present invention, in general terms, there are provided measures and mechanisms for (enabling/realizing) improvements in small cell mobility with dual/multi connectivity.

<FIG> schematically illustrates an inter RAT architecture for multi RAT interworking (LTE-<NUM>) applied to a scenario with LTE and <NUM> mobile communication system, according to exemplary embodiments of the present invention.

In particular, an interworking architecture with common core and multi controller (dual control plane connectivity option (two RRC connections), common AS context, common NAS context) is shown.

The principles behind this architecture are as follows.

Exemplary embodiments of the present invention will be explained utilizing this proposed architecture and the corresponding principles. However, the proposed architecture as well as the corresponding principles may be modified as long as compliant with the features described herein.

As mentioned above, the present invention proposes a solution for optimizing intra- and inter-RAT mobility with reduced signaling during mobility events, minimized service disruption during handovers, wherein embodiments are applicable for both intra-small cell and small cell-to-macro cell mobility.

According to exemplary embodiments of the present invention, the RRC connections of all RATs and radio interfaces of <NUM> are terminated in the proposed multi controller.

Further, according to exemplary embodiments of the present invention, a single UE AS context is established in the multi controller for all the connected RATs(or radio interfaces) of a UE involved in multi connectivity.

It is noted that cmW and mmW are belonging to the same RAT, <NUM>, and hence are called radio interfaces of the same RAT.

In addition, the multi controller logical entity is located/arranged much higher in hierarchy than the access point nodes, i.e., multiple access points or base stations are controlled/managed by the same multi controller. This hierarchy is dependent on the deployment model of the network.

In doing so, the number of mobility events is limited to that of a multi controller instead of to that of each of controlled/managed access points.

<FIG> is a block diagram illustrating an apparatus according to exemplary embodiments of the present invention. The apparatus may be a network node <NUM> (e.g. the above proposed multi controller) for providing, in a control plane for a terminal, connection management for at least a first network access entity and a second network access entity, wherein said at least first network access entity and second network access entity providing radio access for user plane data transfer for said terminal, wherein said terminal being capable of having radio access to said at least first network access entity and second network access entity for user plane data transfer, the network node <NUM> comprising a terminating means <NUM>, a maintaining means <NUM>, and an initiating means <NUM>.

In an embodiment at least some of the functionalities of the apparatus shown in <FIG> may be shared between two physically separate devices forming one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes.

The terminating means <NUM> may terminate at least one control plane signaling connection (e.g. RRC connection) from said terminal for said at least first network access entity and second network access entity. The maintaining means <NUM> may maintain a terminal related access stratum context commonly for radio accesses of said terminal to said at least first network access entity and second network access entity. The initiating means <NUM> may initiate switching of said radio access of said terminal from said first network access entity to said second network access entity for user plane data transfer with said control plane signaling connection for said second network access entity being applied unchanged. <FIG> is a schematic diagram of a procedure according to exemplary embodiments of the present invention. The apparatus according to <FIG> may perform the method of <FIG> but is not limited to this method. The method of <FIG> may be performed by the apparatus of <FIG> but is not limited to being performed by this apparatus.

As shown in <FIG>, a procedure according to exemplary embodiments of the present invention comprises an operation of terminating (S61) at least one control plane signaling connection from the terminal for said at least first network access entity and second network access entity, an operation of maintaining (S62) a terminal related access stratum context commonly for radio accesses of said terminal to said at least first network access entity and second network access entity, and an operation of initiating (S63) switching of said radio access of said terminal from said first network access entity to said second network access entity for user plane data transfer with said control plane signaling connection for said second network access entity being applied unchanged, generally to provide, in a control plane for the terminal, connection management for at least the first network access entity and the second network access entity, wherein the at least first network access entity and second network access entity providing radio access for user plane data transfer for said terminal, wherein said terminal being capable of having radio access to the at least first network access entity and second network access entity for user plane data transfer.

<FIG> is a schematic diagram illustrating details of a multi connectivity architecture according to exemplary embodiments of the present invention. In particular, specifics of an exemplary realization according to embodiments of the present invention of the proposed inter RAT architecture for multi RAT interworking shown in <FIG> are illustrated.

As is derivable from that <FIG>, control plane paths are illustrated by dotted lines, while user plane paths are illustrated by solid lines.

A UE illustrated in <FIG> is able to connect to a Mini-eNB of a LTE network, the user plane services for which is provided by an uGW. Further, the UE illustrated in that Figure is able to connect to a <NUM> access point working at millimeter waves (mmW), the user plane of which is provided by the same or different uGW, and to connect to a <NUM> access point working at centimeter waves (cmW), the user plane of which is provided by the same or different uGW. The control plane for all three connections is provided by a cMGW via the multi controller. Here, the multi controller comprises a dedicated module for the LTE connection terminating the RRC of the LTE connection (RRC-LTE) as well as a dedicated module for the <NUM> connections terminating the RRC of the <NUM> connections (RRC-H, RRC-L-mm, RRC-L-cm, RRC-L-WA). Acronyms used in the Figure and in particular those not being known from LTE specifications are listed at the end of this specification. It is self-evident that the illustrated scenario is just an example for explanation purposes, and more, less, and/or other connections are possible.

<FIG> shows a schematic diagram of signaling sequences according to exemplary embodiments of the present invention. In particular, <FIG> illustrates an implementation of intra-<NUM> small cell mobility according to exemplary embodiments of the present invention. Namely, a <NUM> AP is changed in multi connectivity in the context of intra small cell mobility.

In brief, once the multi controller has knowledge of a preferred target AP of a terminal (which differs from the current AP), the multi controller decides to handover the connection of the terminal, and initiates such handover by causing a handover command to the UE. Once the UE connected to the target <NUM> AP (here: <NUM> AP2) and the target <NUM> AP informed the multi controller thereof, the multi controller updates the common AS context and informs the cMGW on the handover. Here, the updating includes updating tunnel end points of the target <NUM> AP and further updating new configuration info, if changed. Since the multi controller maintains the respective RRC connection(s), there is no need to establish a new RRC connection for the target AP (unless there is a change in the multi controller itself, in which case, there will be a normal handover over X2*). In addition, also a context transfer is not necessary.

Returning to <FIG>, in other words, when said at least first network access entity and second network access entity correspond to at least a first radio interface and a second radio interface of the same radio access technology, respectively (intra-RAT), according to a variation of the method shown in <FIG>, exemplary additional operations and exemplary details of the initiating operation are given, which are inherently independent from each other as such.

According to such variation, an exemplary method according to exemplary embodiments of the present invention may further comprise an operation of receiving a measurement report indicating said second network access entity as preferred target, and such exemplary initiating operation according to exemplary embodiments of the present invention may comprise an operation of transmitting a handover command to said terminal, said handover command instructing switching of said radio access to said second network access entity, and an operation of receiving, from said second network access entity, information indicative of confirmation and configuration details about said radio access of the terminal to said second network access entity.

According to a further variation of the method shown in <FIG>, exemplary details of the initiating operation are given, which are inherently independent from each other as such. Such exemplary initiating operation according to exemplary embodiments of the present invention may comprise an operation of transmitting a service flow reconfiguration request indicative of an intended switching of said radio access of said terminal to said second network access entity, and an operation of receiving a confirmation of said intended switching of said radio access of said terminal to said second network access entity.

According to a further variation of the method shown in <FIG>, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of updating said terminal related access stratum context.

According to a further variation of the method shown in <FIG>, one control plane signaling connection from said terminal is terminated commonly for the at least first network access entity and second network access entity, or alternatively, one control plane signaling connection from said terminal is terminated per each of the at least first network access entity and second network access entity.

In other words, according to one option of exemplary embodiments of the present invention, (only) one RRC connection is maintained for all the radio interfaces of <NUM> (e.g. mm wave, cm wave, and wide area (WA)) in relation to the terminal. However, according to another option of exemplary embodiments of the present invention, one (dedicated) connection per each radio interface of <NUM> (e.g. mm wave, cm wave, and wide area) is maintained in relation to the terminal. As an example of the second option, if the terminal would maintain a mm wave radio interface and a cm wave radio interface, two RRC connections (one for the mm wave radio interface and one for the cm wave radio interface) would be maintained/terminated at the involved multi controller.

While traditional intra RAT handover (HO) involved setting up of a new RRC connection in the target access point and transfer of the UE AS context to the target over X2 interface (if one existed), according to exemplary embodiments of the present the invention, both of these steps can be avoided. It is not necessary to setup the RRC connection freshly, as long as the target access point is also served by the same multi controller. Further, the AS context is not to be transferred to the target AP since both the APs share the same AS context.

According to the exemplary embodiments of the present invention, RRC connection setup and context transfer are required only when the UE changes the multi controller, depending on the hierarchy of the multi controller in the AS network.

<FIG> shows a schematic diagram of signaling sequences according to exemplary embodiments of the present invention. In particular, <FIG> illustrates an implementation of inter-RAT mobility (e.g. from <NUM> to LTE) according to exemplary embodiments of the present invention. Namely, a loss of coverage or traffic steering during multi connectivity is handled.

In brief, once the multi controller has knowledge of a radio link failure (RLF) of a terminal to a <NUM> AP (<NUM> AP1), the multi controller updates the (common) AS context and checks whether the service performed by means of the <NUM> AP is possible in LTE (by the corresponding eNB). Here, the updating includes removal of the tunnel end point on the <NUM> side and stopping of the data forwarding. Further, the multi controller coordinates AP level UP data forwarding between <NUM> and <NUM> (LTE), which means that with the same numbering scheme in both RATs, the multi controller can co-ordinate the (unsuccessfully) sent packets on <NUM>, which otherwise has to be re-transmitted by the CN. This is possible if the network convergence layer (NCS-H) protocol (<NUM>'s packet data control plane (PDCP)) is induced in LTE or PDCP numbering is followed in <NUM>. That is, in more general terms, the multi controller can coordinate forwarding of data intended for transmission utilizing the <NUM> AP to the LTE AP (eNB). Since the multi controller maintains the respective RRC connection(s), there is no need to establish a new RRC connection for the target eNB. In addition, also a context transfer is not necessary.

Returning to <FIG>, in other words, when said at least first network access entity and second network access entity correspond to at least a first radio access technology and a second radio access technology, respectively (inter-RAT), with terminating one control plane signaling connection from said terminal per each of the at least first network access entity and second network access entity, according to a variation of the method shown in <FIG>, exemplary additional operations and exemplary details of the initiating operation are given, which are inherently independent from each other as such.

According to such variation, an exemplary method according to exemplary embodiments of the present invention may further comprise an operation of perceiving a radio link failure with respect to said radio access of said terminal with said first network access entity, and such exemplary initiating operation according to exemplary embodiments of the present invention may comprise an operation of transmitting a message indicative of said radio link failure with respect to said radio access of said terminal with said first network access entity.

According to a still further variation of the method shown in <FIG>, exemplary additional operations are given, which are inherently independent from each other as such. According to such variation, an exemplary method according to exemplary embodiments of the present invention may comprise an operation of coordinating forwarding of data intended for transmission utilizing said radio access of said terminal with said first network access entity to said radio access of said terminal with said second network access entity.

A traditional inter RAT handover would comprise of the following signaling after receiving the measurement reports at the base station, namely, preparation of the target, and handover to the target.

This handover procedure would always use the core network route to communicate to the other RAT. This would involve a lot of signaling.

To the contrary, according to exemplary embodiments of the present invention, this unnecessary signaling is avoided, since a common AS context for both RATs is present at the multi controller.

Accordingly, data forwarding between <NUM> AP and <NUM> eNB can be enabled, as e.g. in intra-<NUM> HOs. This data forwarding may be coordinated by the multi controller in a timely manner. This is possible by having the same packet numbering scheme in both RATs i. e introducing <NUM> packet numbering scheme for LTE; alternatively LTE numbering scheme for LTE.

Further, since in the traditional way the only common node between the RATs was the CN even the AS signaling had to go through NAS elements.

To the contrary, according to exemplary embodiments of the present invention, the RRC connections of both involved RATs are terminated at the proposed multi controller and hence the AS signaling can be limited to take place in the AS only.

While according to the traditional way the length of the signaling procedure results in that big service disruption or user plane break occurred during mobility events, according to exemplary embodiments of the present invention, the reduction of the signaling also results in minimizing the service disruption and reducing the processing overhead on network nodes.

In the foregoing exemplary description of the network node/entity, only the units that are relevant for understanding the principles of the invention have been described using functional blocks. The network entity may comprise further units that are necessary for its respective operation. However, a description of these units is omitted in this specification. The arrangement of the functional blocks of the devices is not construed to limit the invention, and the functions may be performed by one block or further split into sub-blocks.

When in the foregoing description it is stated that the apparatus, i.e. network entity/node (or some other means) is configured to perform some function, this is to be construed to be equivalent to a description stating that a (i.e. at least one) processor or corresponding circuitry, potentially in cooperation with computer program code stored in the memory of the respective apparatus, is configured to cause the apparatus to perform at least the thus mentioned function.

In <FIG>, an alternative illustration of apparatuses according to exemplary embodiments of the present invention is depicted. As indicated in <FIG>, according to exemplary embodiments of the present invention, the apparatus (network node) <NUM>' (corresponding to the network node <NUM>) comprises a processor <NUM>, a memory <NUM> and an interface <NUM>, which are connected by a bus <NUM> or the like, and the apparatus <NUM>' may be connected to another apparatus <NUM> via link <NUM>.

The processor <NUM> and/or the interface <NUM> may also include a modem or the like to facilitate communication over a (hardwire or wireless) link, respectively. The interface <NUM> may include a suitable transceiver coupled to one or more antennas or communication means for (hardwire or wireless) communications with the linked or connected device(s), respectively. The interface <NUM> is generally configured to communicate with at least one other apparatus, i.e. the interface thereof.

The memory <NUM> may store respective programs assumed to include program instructions or computer program code that, when executed by the respective processor, enables the respective electronic device or apparatus to operate in accordance with the exemplary embodiments of the present invention.

According to exemplary embodiments of the present invention, an apparatus representing the network node <NUM> comprises at least one processor <NUM>, at least one memory <NUM> including computer program code, and at least one interface <NUM> configured for communication with at least another apparatus. The processor (i.e. the at least one processor <NUM>, with the at least one memory <NUM> and the computer program code) is configured to perform terminating at least one control plane signaling connection (RRC connection) from said terminal for said at least first network access entity and second network access entity, (thus the apparatus comprising corresponding means for terminating), to perform maintaining a terminal related access stratum context commonly for the radio accesses of said terminal to said at least first network access entity and second network access entity (thus the apparatus comprising corresponding means for maintaining), and to perform initiating switching of said radio access of said terminal from said first network access entity to said second network access entity for user plane data transfer with said control plane signaling connection for said second network access entity being applied unchanged (thus the apparatus comprising corresponding means for initiating).

Any of the operations of transmitting and receiving referred to in the foregoing can be performed by a transmitter and a receiver respectively and any entities discussed herein performing transmitting or receiving may be provided with, for example may contain, such a transmitter or receiver in the form of hardware for this purpose. This also applies to any of communication over a (hardwire or wireless) link discussed herein.

For the purpose of the present invention as described herein above, it should be noted that.

Generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the present invention. Devices and means can be implemented as individual devices, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device is preserved. Such and similar principles are to be considered as known to a skilled person.

Claim 1:
A method, of a network node (<NUM>, <NUM>'), for providing, in a control plane for a terminal, connection management for at least a first network access entity and a second network access entity, wherein said at least first network access entity and second network access entity providing radio access for user plane data transfer for said terminal and being connectable to said network node, wherein said terminal being capable of having radio access to said at least first network access entity and second network access entity for user plane data transfer,
the method comprising
terminating (S61) at least one control plane signaling connection from said terminal for said at least first network access entity and second network access entity,
maintaining (S62) a common terminal related access stratum context for radio accesses of said terminal to said at least first network access entity and second network access entity, and
initiating (S63) switching of said radio access of said terminal from said first network access entity to said second network access entity for user plane data transfer with said control plane signaling connection for said second network access entity being applied unchanged.