EP3791626A1

EP3791626A1 - Maintaining radio network system selection

Info

Publication number: EP3791626A1
Application number: EP18731892.8A
Authority: EP
Inventors: Malgorzata Tomala; Gyorgy Wolfner
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2018-05-10
Filing date: 2018-05-10
Publication date: 2021-03-17
Also published as: WO2019215479A1

Abstract

A method including receiving a first signal at a first core network entity of a first radio network system that a user equipment, coupled to a first radio access network entity of the first radio network system, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the first signal by the first core network entity, transmitting a second signal from the first core network entity to the first radio access network entity indicating that the user equipment has disabled the capability in regard to the second radio network system.

Description

Maintaining Radio Network System Selection

BACKGROUND

Technical Field

[0001] The exemplary and non-limiting embodiments relate generally to radio communication and, more particularly, to maintaining a radio network system selection.

Brief Description of Prior Developments

[0002] Various radio network systems are known such as 3G, 4G, and 5G for example. A 4G radio network system may have an evolved packet core (EPC) as a core network element. A 5G radio network system may have a 5G network core (5GCN) as a core network element.

[0003] The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:

3GPP 3rd Generation Partnership Project

4G 4^th Generation of. broadband cellular network technology

5G 5^th Generation of broadband cellular network technology 5GC 5G core

5GCN 5G network core

5GS 5G system

AS Access Stratum

CN core network eNB Evolved Node-B

EPC evolved packet core

HO Handover

LTE long term evolution

NAS Non-Access Stratum

NR New Radio

RAN radio access network

PLMN public land mobile network

UE user equipment

SUMMARY

[ 0004 ] The following summary is merely intended to be exemplary. The summary is not intended to limit the scope of the claims.

[ 0005 ] In accordance with one aspect, an example method comprises receiving a first signal at a first core network entity of a first radio network system that a user equipment, coupled to a first radio access network entity of the first radio network system, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the first signal by the first core network entity, transmitting a second signal from the first core network entity to the first radio access network entity indicating that the user equipment has disabled the capability in regard to the second radio network system.

[ 0006 ] In accordance with another aspect, an example method comprises receiving a signal at a first radio access network entity from a first core network entity of a first radio network system, where the signal indicates that a user equipment, coupled to the first radio access network entity, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the signal from the first core network entity, the first radio access network entity avoiding handover of the user equipment to a second radio access network entity of the different second radio network system.

[ 0007 ] In accordance with another aspect, an example method comprises receiving a request for a handover by a first radio access network entity regarding a user equipment coupled to the first radio access network entity, where the first radio access network entity is coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and the first radio access network entity preventing the handover of the user equipment to the second radio network system based, at least partially, upon a signal received by the first radio access network entity from the first core network entity of the first radio network system.

[ 0008 ] In accordance with another aspect, an example method comprises receiving a request by a second radio access network entity for a handover of a user equipment coupled to a first radio access network entity, where the first and second radio access network entities are coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and receiving a signal by the second radio access network entity from at least one of the first radio access network entity or the first core network entity indicating that the second radio access network entity should not handover the user equipment to a radio access network entity of the second radio network system.

BRIEF DESCRIPTION OF THE DRAWINGS

[ 0009 ] The foregoing aspects and other features are explained in the following description, taken in connection with the accompanying drawings, wherein: [0010] Fig. 1 is a diagram illustrating two different types of radio network systems which a user equipment is operable with;

[0011] Fig. 2 is a diagram illustrating some components of the user equipment and a first one of the radio network systems shown in Fig. 1;

[0012] Fig. 3 is a diagram illustrating some components of the user equipment and a second one of the radio network systems shown in Fig. 1;

[0013] Fig. 4 is a diagram illustrating some steps in an example method;

[0014] Fig. 5 is a diagram illustrating an example method;

[0015] Fig. 6 is a diagram illustrating an example method;

[0016] Fig. 7 is a diagram illustrating an example method; and

[0017] Fig. 8 is a diagram illustrating an example method.

DETAILED DESCRIPTION OF EMBODIMENTS

[0018] Fig. 1 illustrates a user equipment (UE) 110 shown connected to a first radio network system 100. The UE 110 is also configured to be able to connect to a different second radio network system 200. In the examples illustrated below, the first radio network system 100 is a 4G LTE radio network system and the second radio network system 200 is a 5G radio network system. However, features as described herein may be used with other different types of radio network systems,

[0019] The first radio network system 100 includes one or more first core network entities 190 and one or more radio access network (RAN) entities 170. In this example the first core network entity 190 is an evolved packet core ( EPC) and the RAN entities 170 are base stations comprising an eNB. The UE 110 is shown connected to one of the eNB 170 by a wireless radio link or channel 111.

[0020] The second radio network system 200 includes one or more second core network entities 290 and one or more radio access network (RAN) entities 270. In this example the second core network entity 290 is a 5G core network (5GCN) and the RAN entities 270 are base stations comprising a gNB. The UE 110 is configured to be able to connect to the gNBs 270 as indicated by the wireless radio link or channel 211. Thus, the UE 110 may optionally use the first radio network system 100 or the second radio network system 200.

[0021] Turning to Fig. 2, this figure shows a block diagram of one possible and non-limiting exemplary system in which the exemplary embodiments may be practiced. In Fig. 2, the user equipment (UE) 110 is in wireless communication with the first radio network system 100. The UE is a wireless, typically mobile, device that can access the wireless network. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver (Rx) 132 and a transmitter (Tx) 133. The one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a restriction module 140, comprising one of or both parts 140-1 and/or 140-2, which may be implemented in a number of ways. The restriction module 140 may be implemented in hardware as restriction module 140-1, such as being implemented as part of the one or more processors 120. The restriction module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the restriction module 140 may be- implemented as restriction module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120. For instance, the one or more memories 125 and the computer program code 123 may be configured to, with the one or more processors 120, cause the user equipment 110 to perform one or more of the operations as described herein. The UE 110 communicates with eNB 170 via the wireless link 111.

[0022] The eNB 170 is a base station that provides access by wireless devices . such as the UE 110 to the first radio network system 100. The eNB 170 includes one or more processors -152, one or more memories 155, one or more network interfaces (N/W I/F(s)} 161, and one or more transceivers 160 interconnected through one or more buses 157. Each of the one or more transceivers 160 includes a receiver (Rx) 162 and a transmitter (Tx) 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The eNB 170 includes a configuration module, comprising one of dr both parts 150-1 and/or 150-2, which may be implemented in a number of ways. The configuration module may be implemented in hardware as configuration module 150-1, such as being implemented as part of the one or more processors 152. The configuration module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the configuration module may be implemented as configuration module 150-2, which is implemented as computer program code 153 and is executed by the one or more processors 152. For instance, the one or more memories 155 and the computer program code 153 are configured to, with the one or more processors 152, cause the eNB 170 to perform one or more of the operations as described herein. The one or more network interfaces 161 communicate over a network such as_. via the links 176 and 131. Two or more eNBs 170 and/or gNBs 270 communicate using, for example, link 176. The link 176 may be wired or wireless or both and may implement, for example, an X2 interface.

[0023] The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on. a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195, with the other elements of the eNB 170 being physically in a different locatioh from the RRH, and the one or more buses 157 could be implemented in part as fiber optic cable to connect the other elements of the eNB 170 to the RRH 195.

[0024] It is noted that description herein indicates that "cells" perform functions, but it should be clear that the eNB that forms the cell will perform the functions. The cell makes up part of an eNB. That is, there can be multiple cells per eNB. For instance, there could be three cells for a single eNB carrier frequency and associated bandwidth, each cell covering one-third of a 360 degree area so that the single eNB' s coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and an eNB may use multiple carriers. So if there are three 120 degree cells per carrier and two carriers, then the eNB has a total of 6 cells.

[0025] The first radio network system 100 may include one or more core network elements or network control elements (NCE) 190 that may include MME (Mobility Management Entity) and/or SGW (Serving Gateway) functionality, and which provides connectivity with a further network, such as a telephone network and/or a data communications network (for example, the Internet) . The eNB 170 is coupled via a link 131 to the NCE 190. The link 131 may be implemented as, for example, an SI interface. The NCE 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N/W l/F(s)) 180, interconnected through one or more buses 185, The one or more memories 171 include computer program code 173. The one or more memories 171 and the computer program code 173 are configured to, with the one or more processors 175, cause the NCE 190 to perform one or more operations.

[0026] Those skilled in the art will appreciate that the various network elements shown in Fig. 2 may be implemented differently in future wireless networks. For example, the terms NCE, MMX, and SGW are terms generally used for the core elements in a LTE network. In contrast to LTE, future wireless -networks may carry out network functions (NFs) by a plurality of cooperating devices. The different NFs, may include for example', Access and Mobility Function (AMF) , Session Management Function (SMF) , Policy Control Function (PCF), Application Function (AF) , Authentication Server Function (AUSF) , User Plane Function (UPF) , and User Data Management (UDM) . These NFs may be a virtualized function instantiated on an appropriate platform, such as a cloud infrastructure. For example, certain protocols (such as non real-time protocols for example) may be performed by one or more centralized units (CUs) in a cloud infrastructure, while one or more distributed units (DUs) operate the remaining protocols (e.g. real-time protocols) of the radio interface. In this way, the various NFs may be split between CUs and DUs. Together a CU, underlying DUs, and RRHs may be considered as forming a logical base station (which may be represented by eNB 170 in Fig. 2 for example) .

[0027] The first radio network system 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171, and also such virtualized entities create technical effects.

[0028] The computer readable memories 125, _.155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer readable memories 125, 155, and 171 may be means for performing storage functions. The processors 120, 152, and 175 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi core processor architecture , as non-limiting examples. The processors 120, 152, and 175 may be means for performing functions, such as controlling the UE 110, eNB 170, and other functions as described herein.

[0029] In general, the various example embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, tablets, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations off such functions .

[ 0030 ] Referring also to Fig. 3, the RAN entity in this example is a gNB 270 provided as a base station that provides access by wireless devices such as the UE 110 to the second radio network system 200. The gNB 270 includes one or more processors 252, one or more memories 255, one or more network interfaces {N/W I/F(s)) 261, and one or more transceivers 260 interconnected through one or more buses 257. Each of the one or more transceivers 260 includes a receiver (Rx) 262 and a transmitter (Tx) 263. The one or more transceivers 260 are connected to one or more antennas 258. The one or more memories 255 include computer program code 253. The gNB 270 includes a configuration module, comprising one of or both parts 250-1 and/or 250-2, which may be implemented in a number of ways. The configuration module may be implemented in hardware as configuration module 250-1, such as being implemented as part of the one or more processors 252. The configuration module 250-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the configuration module may be implemented as configuration module 250-2, which is implemented as computer program code 253 and is executed by the one or more processors 252. For instance, the one or more memories 255 and the computer program code 253 are configured to, with the one or more processors 252, cause the gNB 270 to perform one or more of the operations as described herein. The one or more network interfaces 261 communicate over a network such as via the links 176 and 231. Two or more eNBs 170 and/or gNBs 270 communicate using, for example, link 176. The link 176 may be wired or wireless or both and may implement, for example, an X2 interface.

[0031] The one or more buses 257 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 260 may be implemented as a remote radio head (RRH) 295, with the other elements of the gNB 270 being physically in a different location from the RRH, and the one or more buses 257 could be implemented in part as fiber optic cable to connect the other elements of the gNB 270 to the RRH 295.

[0032] It is noted that description herein indicates that "cells" perform functions, but it should be clear that the gNB that forms the cell will perform the functions. The cell makes up part of an gNB. That is, there can be multiple cells per gNB. For instance, there could be three cells for a single gNB carrier frequency and associated bandwidth, each cell covering one-third of a 360 degree area so that the single gNB' s coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and an gNB may use multiple carriers. So if there are three 120 degree cells per carrier and two carriers, then the gNB has a total of 6 cells.

[ 0033] The second radio network system 200 may include one or more core network elements or network control elements 290 that may include Access and Mobility Function (AMF) , MME (Mobility Management Entity} and/or SGW (Serving Gateway) functionality, and which provides connectivity with a further network, such as a telephone network and/or a data communications network (for example, the Internet) . The gNB 270 is coupled via a link 231 to the core network element 290. The link 231 may be implemented as, for example, an Si interface. The core network element 290 includes one or more processors 275, one or more memories 271, and one or more network interfaces (N/W I/F ( s ) ) 280, interconnected through one or more buses 285. The one or more memories 271 include computer program code 273. The one or more memories 271 and the computer program code 273 are configured to, with the one or more processors 275, cause the core network element 290 to perform one or more operations.

[ 0034 ] Those skilled in the art will appreciate that the various network elements shown in Fig. 3 may be implemented differently in future wireless networks. Wireless networks may carry out network functions (NFs) by a plurality of cooperating devices. The different NFs, may include for example, Session Management Function ( SMF) , Policy Control Function (PCF) , Application Function (AF) , Authentication Server Function (AUSF) , User Plane Function (UPF) , and User Data Management (UDM) . These NFs may be a virtualized function instantiated on an appropriate platform, such as a cloud infrastructure. For example, certain protocols (such as non real-time protocols for example) may be performed by one or more centralized units (CUs) in a cloud infrastructure, while one or more distributed units (DUs) operate the remaining protocols (e.g. real-time protocols) of the radio interface. In this way, the various NFs may be split between CUs and DUs. Together a CU, underlying DUs, and RRHs may be considered as forming a logical base station.

[0035] The second radio network system 200 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 252 or 275 and memories 255 and 271, and also such virtualized entities create technical effects. [0036] The computer readable memories 225, 255, and 271 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer readable memories 225, 255, and 271 may be means for performing storage functions. The processors 220, 252, and 275 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi core processor architecture, as non-limiting examples. The processors 220, 25_.2, and 275 may be means for performing functions, such as controlling the UE 110, gNB 270, and other functions as described herein. For 5G wireless systems, the link 231 may represent a 5G interface, such as NG2 or NG3 for example.

[0037] Features as described herein may be used to address a situation when a network core element for one radio network -system may not support all features supported by a core network element of another radio network system.

[0038] Features as described herein may be used to introduce priorities to maintain UE connectivity to a first network core element, such as EPC for example, when a UE capability for use of the UE in a second network core element, such as 5GCN for example, has been recognized and disabled by a UE . Non-Access Stratum (NAS) layer . [ 0039 ] To ensure US connectivity to EPC in LTE deployments mixed with New Radio (NR) or 5G, the priorities to steer the UE connectivity concern, at the

RAN node, the RAN entity being involved to get the information regarding 5G system { 5GS ) disabled capabilities for better steering of the UE in handover

(HO) . The UE 110 wishing to use a service (such as IP Multimedia Subsystem (IMS) voice or Multimedia Broadcast Multicast Services (MBMS) for example) that is supported by a first radio network system (such as 4G LTE for example) , but not supported in a second radio network system (such as 5GS for example) will need to either stay on the first radio network system (4G LTE for example) or, if on the second radio network system (5GS for example) , switch to the first radio network system (4G LTE system; to get redirected to the EPC) . The triggers and solutions to redirect the UE to EPC are limited to the UE NAS layer. The 3GPP standard defines the requirement that UE NAS layer and IDLE UE NAS procedure should reselect a public land mobile network (PLMN) that guarantees connection to an LTE core, i.e. EPC. The information resides in the UE 110 and is exchanged between NAS and Access Stratum (AS) layer to perform cell reselection process. Because of an assumption that the NAS layer in the UE also informs the AS layer in the UE about the core network (CN) type (EPC and/or 5GC for example) to be selected, one might assume that the UE can perform the cell reselection in IDLE mode among the cells that support the required CN type. However, in a CONNECTED mode the RAN node (eNB in case of E-UTRA) selects a target cell that is supported by the UE radio capabilities when handover (HO) is necessary. When Nl mode is disable at NAS level, the serving eNB should not select a target cell (e.g. an E-UTRA cell that is connected only to 5GC or NR cell) that is not connected to EPC, but the UE radio capabilities are not changed. With the introduction of E-UTRA cells connected to 5GC there is no one-to-one relation between the UE radio capabilities and NAS level capabilities. The eNB would have been unaware of the disabled NAS level functionality in the UE. Features as described herein, however, allow for the RAN entity to know about the disabled NAS level functionality in the UE .

[ 0040 ] With features as described herein, - in the 4G LTE and 5G example noted above, the 'Nl mode disable' function in the UE 110 may trigger the following steps:

• the UE NAS idle mode function is responsible for PLMN order;

• the UE AS idle mode procedures support the PLMN selection provided by NAS; and

• the UE AS idle mode procedures introduce new priorities for cells selection based on core type determined based on System Information provided by eNB/gNB.

In this example, eNB/gNB procedures introduce a new information element for the core network (CN) {EPC 190) to get that new information regarding the Nl disabled mode from the UE 110. The Information Element regarding N1/5GS disabled may be made available to the RAN node from the CN entity. In this example, the Information Element may be sent to the eNB 170 from the EPC 190. The Information Element may be stored in the RAN entity to avoid handover to the -disabled system. In this example, the Information Element may be stored in the eNB 190 to avoid handover of the UE 110 to a RAN entity of the 5GS.

[ 0041 ] Referring also to Fig. 4, after the UE 110 disables the Nl mode at 300, the UE NAS selects PLMN priorities following the Nl disabled mode as indicated by 302. As indicated by 304, the UE then reselects a cell that has a connection to EPC, and an indication is sent by a NAS message to the EPC 190 that the Nl mode is not supported by the UE as indicated by 306. 306 shows that an indication that the Nl mode is not supported is sent at NAS level from the UE to the core network element. As indicated by 308, the EPC 190 then sends a signal to the eNB 170 that the Nl mode for the UE 110 is not supported. 308 shows that an indication that the Nl mode is not supported is sent in Sl-AP message from the core network element to the eNB that then stores this information and uses it when a target cell is selected for handover. Steps 6, 7 and 8 may occur as indicated by 310, 312, 314 regarding RRC and measurement with neighbors for purposes of handover (HO) . In the event handover of the UE 110 to another RAN entity is needed, as indicated by step 9 at 316 the eNB may select a target cell that has an EPC connection; avoiding a 5GCN connection.

[ 0042 ] An advantage of the method described above is consistent maintenance of UE context in case of dual core availability. Since radio conditions may take precedence over service priorities, NAS procedures disabling 5GS mode in the UE are respected. At the same time actual UE radio capabilities remain unchanged and unhidden, which may be crucial for radio connectivity in case the same radio cell can be connected to two cores. Note also that updating the UE radio capabilities is otherwise complex, and may also result in full service interruption such as, for example, in a case when the UE moves into an area where only 5G NR cells are available.

[ 0043 ] 3GPP TS 23.501 V15.1.0 (2018-03) defines support for migration from EPC to 5GC. 5G system in Rel-15 does not support some of the functionalities supported in EPS such as ProSe, MBMS, CIOT optimizations, V2X etc. For this purpose, the UE that wants to use one or more of the functionalities not supported by 5G System, when "in CM- IDLE may disable all the related radio capabilities that allow the UE to access only 5G System". The triggers to disable the 5GS capabilities to access 5G System are guided in 3GPP TS 24.501 VI.0.0 (2018-03) including:

• If the UE is capable of both N1 mode and S 1 mode and lower layers provide an indication that the current E-UTRA cell is connected to both EPC and 5GCN, the UE shall select a core network type (EPC or 5GCN) based on the PLMN selection procedures as specified in 3GPP TS 23.122. (..)

• If the UE supporting both Nl mode and S 1 mode is disabling the Nl mode radio capability, it should proceed as follows: o select an E-UTRA celhconnected to EPC of the registered PLMN or a PLMN from the list of equivalent PLMNs;

[ 0044 ] With features as described herein, a UE which needs to remain on a first radio network system for a certain functionality not supported by a second radio network system, can be prevented from being inadvertently redirected to the second radio network system. [ 0045 ] Features as described herein may be used to address a problem that may arise when new 5G radio systems are installed in parallel to conventional (4G) systems. The new core network 5GC may not support all features supported by the EPC. Therefore, if a dual compatibility UE (both 4G and 5G capable) wishes to use one of these features not-supported by 5GC, procedures are defined herein to ensure that the UE will connect to EPC (and not to 5GC) . Please note that the basic principle works for any two different radio network systems. 4G and 5G (EPC and 5GC) are only used as one example. Connection to EPC may be achieved by disabling the UE capabilities to access the 5G system. Features as described herein may be used to address a problem that may arise when dual compatibilities of the UE would lead to the condition of poorer quality or worse performance (for example power consumption).

[ 0046] In CONNECTED mode, when a handover is to be performed it is up to the source cell to select a proper target cell. However, without features as described herein, the source cell (e.g. eNB) has not been informed about the UE' s wish to connect to EPC (see above), the selection is performed solely based on the UE radio capabilities. Without features as described herein, as these (still) indicate (to the RAN) that the UE is indeed 5G capable, the source cell may indeed select a target cell that only has 5GC connection. This would lead to an erroneous handover to the actually disabled 5G system.

[ 0047 ] Features as described herein, however, allow the RAN to be informed about the disabling of the UE's 5G capabilities. This is done via new signaling from the CN to the RAN, see message 5 of Fig. 4. As shown by step 9 in Fig. 4, the RAN is then enabled to always select a target cell that has EPC connection.

[ 0048 ] Referring also to Fig. 5, an example embodiment may be provided in a method comprising: as indicated by block 400, receiving a first signal at a first core network entity of a first radio network system that a user equipment, coupled to a first radio access network entity of the first radio network system, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the first signal by the first core network entity, transmitting a second signal from the first core network entity to the first radio access network entity indicating that the user equipment has disabled the capability in regard to the second radio network system, as indicated by block 402.

[ 0049 ] The method may comprise the first signal received at the first core network entity comprise information from the user equipment. The method may comprise the first signal comprising an information element comprising a N1 mode radio capability disabled. The method may comprise the first core network entity being an evolved packet core network entity. The method may comprise the second signal indicating that the first radio access network entity should not handover the user equipment to the second core network entity of the second radio network system. The method may comprise the second signal indicating that the first radio access network entity should not handover the user equipment to a 5G network core. The method may comprise the second signal comprising information to indicate to the first radio access network to generate a handover restriction list.

[0050] An example embodiment may be provide in an apparatus comprising: means for receiving a first signal at the apparatus that a user equipment, coupled to a first radio access network entity of the first radio network system, has disabled a capability in regard to a different second radio network system having a different second core network entity, where the apparatus comprises a first core network entity of a first radio network system; and means for, based upon receipt of the first signal by the first core network entity, transmitting a second signal from the first core network entity to the first radio access network entity indicating that the user equipment has disabled the capability in regard to the second radio network system.

[0051] The first signal received at the first core network entity may comprise information from the user equipment. The first signal may comprise an information element comprising a N1 mode radio capability disabled. The first core network entity may be an evolved packet core network entity. The second signal may be configured to indicate that the first radio access network entity should not handover the user equipment to the second core network entity of the second radio network system. The second signal may be configured to indicate that the first radio access network entity should not handover the user equipment to a 5G network core. The second signal may comprise information to indicate to the first radio access network to generate a handover restriction list. [0052] An example embodiment may be provide in an apparatus comprising a non-transitory program storage device readable by a machine, such as memory 155 for example, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising: determining receipt of a first signal at a first core network entity of a first radio network system that a user equipment, coupled to a first radio access network entity of the first radio network system, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the first signal by the first core network entity, transmitting a second signal from the first core network entity to the first radio access network entity indicating that the user equipment has disabled the capability in regard to the second radio network system.

[0053] An example embodiment may be provide in an apparatus comprising at least one processor; and at least one non-transitory memory including computer program code, such as memory 155 for example, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: determining receipt of a first signal at a first core network entity of a first radio network system that a user equipment, coupled to a first radio access network entity of the first radio network system, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the first signal by the first core network entity, transmit a second signal from the first core network entity to the first radio access network entity indicating that the user equipment has disabled the capability in regard to the second radio network system.

[0054] Referring also to Fig. 6, an example embodiment may be provided in a method comprising: as indicated by block 404, receiving a signal at a first radio access network entity from a first core network entity of a first radio network system, where the signal indicates that a user equipment, coupled to the first radio access network entity, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the signal from the first core network entity, the first radio access network entity avoiding handover of the user equipment to a second radio access network entity of the different second radio network system, as indicated by block 406.

[0055] The signal may comprise an information element indicating that a N1 mode radio capability of the user equipment is disabled. The first core network entity may be an evolved packet core network entity. The second radio network system may be a 5G radio network system and the second core network entity comprises a 5G network core, and where the signal may be configured to indicate that the first radio access network entity should not handover the user equipment to the 5G radio network system.

[0056] An example embodiment may be provide in an apparatus comprising means for receiving a signal at the apparatus from a first core network entity of a first radio network system, where the apparatus comprises a first radio access network entity, and where the signal indicates that a user equipment, coupled to the first radio access network entity, has disabled a capability in regard to a different second radio network system having a different second core network entity; and means for, based upon receipt of the signal from the first core network entity, avoiding handover of the user equipment by the a first radio access network entity to a second radio access network entity of the different second radio network system.

[0057] An example embodiment may be provide in an apparatus comprising a non-transitory program storage device, such as memory 155 for example, readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising: determining receipt of a signal at a first radio access network entity from a first core network entity of a first radio network system, where the signal indicates that a user equipment, coupled to the first radio access network entity, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the signal from the first core network entity, the first radio access network entity avoiding handover of the user equipment to a second radio access network entity of the different second radio network system.

[0058] An example embodiment may be provide in an apparatus comprising at least one processor; and at least one non-transitory memory including computer program code, such as memory 155 for example, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: determining receipt of a signal at a first radio access network entity from a first core network entity of a first radio network system, where the signal indicates that a user equipment, coupled to the first radio access network entity, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the signal from the first core network entity, avoid handover of the user equipment to a second radio access network entity of the different second radio network system.

[0059] Referring also to Fig. 7, an example embodiment may be provided in a method comprising: as indicated by block 408, receiving a request for a handover by a first radio access network entity regarding a user equipment coupled to the first radio access network entity, where the first radio access network entity is coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and the first radio access network entity preventing the handover of the user equipment to the second radio network system based, at least partially, upon a signal received by the first radio access network entity from the first core network entity of the first radio network system, as indicated by block 410.

[0060] An example embodiment may be provide in an apparatus comprising means for receiving a request for a handover by the apparatus regarding a user equipment coupled to the apparatus, where the apparatus comprises a first radio access network entity, where the first radio access network entity is coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and means for preventing the handover of the user equipment by the first radio access network entity to the second radio network system based, at least partially, upon a signal received by the first radio access network entity from the first core network entity of the first radio network system.

[0061] An example embodiment may be provide in an apparatus comprising a non-transitory program storage device, such as memory 155 for example, readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising: receiving a request for a handover by a first radio access network entity regarding a user equipment coupled to the first radio access network entity, where the first radio access network entity is coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and the first radio access network entity preventing the handover of the user equipment to the second radio network system based, at least partially, upon a signal received by the first radio access network entity from the first core network entity of the first radio network system.

[0062] An example embodiment may be provide in an apparatus comprising at least one processor; and at least one non-transitory memory including computer program code, such as memory 155 for example, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: receive a request for a handover by a first radio access network entity regarding a user equipment coupled to the first radio access network entity, where the first radio access network entity is coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and prevent the handover of the user equipment to the second radio network system based, at least partially, upon a signal received by the first radio access network entity from the first core network entity of the first radio network system.

[0063] Referring also to Fig. 8, an example embodiment may be provided in a method comprising: as indicated by block 412, receiving a request by a second radio access network entity for a handover of a user equipment coupled to a first radio access network entity, where the first and second radio access network entities are coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and receiving a signal by the second radio access network entity from at least one of the first radio access network entity or the first core network entity indicating that the second radio access network entity should not handover the user equipment to a radio access network entity of the second radio network system, as indicated by block 414.

[ 00 64 ] An example embodiment may be provide in an apparatus comprising means for receiving a request for a handover by the apparatus regarding a user equipment coupled to the apparatus, where the apparatus comprises a first radio access network entity, and where the first radio access network entity is coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and means for preventing the handover of the user equipment from the first radio access network entity to the second radio network system based, at least partially, upon a signal received by the first radio access network entity from the first core network entity of the first radio network system.

[ 0065 ] An example embodiment may be provide in an apparatus comprising a non-transitory program storage device, such as memory 155 for example, readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising: receiving a request by a second radio access network entity for a handover of a user equipment coupled to a first radio access network entity, where the first and second radio access network entities are coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and receiving a signal by the second radio access network entity from at least one of the first radio access network entity or the first core network entity indicating that the second radio access network entity should not handover the user equipment to a radio access network entity of the second radio network system.

[ 0066] . An example embodiment may be provide in an apparatus comprising at least one processor; and at least one non-transitory memory including computer program code, such as memory 155 for example, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: receive a request by a second radio access network entity for a handover of a user equipment coupled to a first radio access network entity, where the first and second radio access network entities are coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and receive a signal by the second radio access network entity from at least one of the first radio access network entity or the first core network entity indicating that the second radio access network entity should not handover the user equipment to a radio access network entity of the second radio network system.

[ 0067 ] With features as described herein, an explicit message saying that Nl mode is not supported may be sent to the CN. "Nl mode is supported" may be sent to the CN and it can be, thus, inferred from the absence of the "Nl mode is supported" message that Nl mode is indeed not supported .

[ 0068 ] It should be understood that the foregoing description is only illustrative. Various alternatives and modifications can be devised by those skilled in the art. For example, features recited in the various dependent claims could be combined with each other in any suitable combination (s) . In addition, features from different embodiments described above could be selectively combined into a new embodiment. Accordingly, the description is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

Claims

CLAIMS What is claimed is:

1. A method comprising: receiving a first signal at a first core network entity of a first radio network system that a user equipment, coupled to a first radio access network entity of the first radio network system, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the first signal by the first core network entity, transmitting a second signal from the first core network entity to the first radio access network entity indicating that the user equipment has disabled the capability in regard to the second radio network system.

2. A method as in claim 1 where the first signal received at the first core network entity comprise information from the user equipment.

3. A method as in any one of claims 1-2 where the first signal comprises an information element comprising a Nl mode radio capability disabled.

4. A method as in any one of claims 1-3 where the first core network entity is an evolved packet core network entity.

5. A method as in any one of claims 1-4 where the second signal indicates that the first radio access network entity should not handover the user equipment to the second core network entity of the second radio network system.

6. A method as in claim 5 where the second signal indicates that the first radio access network entity should not handover the user equipment to a 5G network core.

7. A method as in any one of claims 1-6 where the second signal comprises information to indicate to the first radio access network to generate a handover restriction list .

8. An apparatus comprising: means for receiving a first signal at the apparatus that a user equipment, coupled to a first radio access network entity of the first radio network system, has disabled a capability in regard to a different second radio network system having a different second core network entity, where the apparatus comprises a first core network entity of a first radio network system; and means for, based upon receipt of the first signal by the first core network entity, transmitting a second signal from the first core network entity to the first radio access network entity indicating that the user equipment has disabled the capability in regard to the second radio network system.

9. An apparatus as in claim 8 where the first signal received at the first core network entity comprise information from the user equipment.

10. An apparatus as in any one of claims 8-9 where the first signal comprises an information element comprising a N1 mode radio capability disabled.

11. An apparatus as in any one of claims 8-10 where the first core network entity is an evolved packet core network entity.

12. An apparatus as in any one of . claims 8-11 where the second signal is configured to indicate that the first radio access network entity should not handover the user equipment to the second core network entity of the second radio network system.

13. An apparatus as in claims 12 where the second signal is configured to indicate that the first radio access network entity should not handover the user equipment to a 5G network core.

14. An apparatus as in any one of claims 8-13 where the second signal comprises information to indicate to the first radio access network to generate a handover restriction list.

15. A non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising: receiving a first signal at a first core network entity of a first radio network system that a user equipment, coupled to a first radio access network entity of the first radio network system, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the first signal by the first core network entity, transmitting a second signal from the first core network entity to the first radio access network entity indicating that the user equipment has disabled the capability in regard to the second radio network system.

16. A method comprising: receiving a signal at a first radio access network entity from a first core network entity of a first radio network system, where the signal indicates that a user equipment, coupled to the first radio access network entity, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the signal from the first core network entity, the first radio access network entity avoiding handover of the user equipment to a second radio access network entity of the different second radio network system..

17. A method as in claim 16 where the signal comprises an information element indicating that a N1 mode radio capability of the user equipment is disabled.

18. A method as in any one of claims 16-17 where the first core network entity is an evolved packet core network entity.

19. A method as in any one of claims 16-18 where the second radio network system is a 5G radio network system and the second core network entity comprises a 5G network core, and where the signal indicates that the first radio access network entity should not handover the user equipment to the 5G radio network system.

20. An apparatus comprising: means for receiving a signal at the apparatus from a first core network entity of a first radio network system, where the apparatus comprises a first radio access network entity, and where the signal indicates that a user equipment, coupled to the first radio access network entity, has disabled a capability in regard to a different second radio network system having a different second core network entity; and means for, based upon receipt of the signal from the first core network entity, avoiding handover of the user equipment by the a first radio access network entity to a second radio access network entity of the different second radio network system.

21. An apparatus as in claim 20 where the signal comprises an information element indicating that a Nl mode radio capability of the user equipment is disabled.

22. An apparatus as in any one of claims 20-21 where the first core network entity is an evolved packet core network entity.

23. An apparatus as in any one of claims 20-22 where the second radio network system is a 5G radio network system and the second core network entity comprises a 5G network core, and where the signal is configured to indicate that the first radio access network entity should not handover the user equipment to the 5G radio network system.

24. A non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising: determining receipt of a signal at a first radio access network entity from a first core network entity of a first radio network system, where the signal indicates that a user equipment, coupled to the first radio access network entity, has disabled a capability in regard to a different second radio network system having a different second core network entity; and based upon receipt of the signal from the first core network entity, the first radio access network entity avoiding handover of the user equipment to a second radio access network entity of the different second radio network system.

25. A method comprising: receiving a request for a handover by a first radio access network entity regarding a user equipment coupled to the first radio access network entity, where the first radio access network entity is coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and the first radio access network entity preventing the handover of the user equipment to the second radio network system based, at least partially, upon a signal received by the first radio access network entity from the first core network entity of the first radio network system.

26. A method as in claim 25 where the signal comprises an information element indicating that a N1 mode radio capability of the user equipment is disabled.

27. A method as in any one of claims 25-26 where the first core network entity is an evolved packet core network entity.

28. A method as in any one of claims 25-27 where the second radio network system is a 5G radio network system and the second core network entity comprises a 5G network core, and where the signal indicates that the first radio access network entity should not handover the user equipment to the 5G radio network system.

29. An apparatus comprising: means for receiving a request for a handover by the apparatus regarding a user equipment coupled to the apparatus, where the apparatus comprises a first radio access network entity, where the first radio access network entity is coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and means for preventing the handover of the user equipment by the first radio access network entity to the second radio network system based, at least partially, upon a signal received by the first radio access network entity from the first core network entity of the first radio network system.

30. An apparatus as in claim 29 where the signal comprises an information element indicating that a Nl mode radio capability of the user equipment is disabled.

31. An apparatus as in any one of claims 29-30 where the first core network entity is an evolved packet core network entity.

32. An apparatus as in any one of claims 29-31 where the second radio network system is a 5G radio network system and the second core network entity comprises a 5G network core, and where the signal is configured to indicate that the first radio access network entity should not handover the user equipment to the 5G radio network system.

33. A non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising: determining receipt of a request for a handover by a first radio access network entity regarding a user equipment coupled to the first radio access network entity, where the first radio access network entity is coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and the first radio access network entity preventing the handover of the user equipment to the second radio network system based, at least partially, upon a signal received by the first radio access network entity from the first core network entity of the first radio network system.

34. A method comprising: receiving a request by a second radio access network entity for a handover of a user equipment coupled to a first radio access network entity, where the first and second radio access network entities are coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and receiving a signal by the second radio access network entity from at least one of the first radio access network entity or the first core network entity indicating that the second radio access network entity should not handover the user equipment to a radio access network entity of the second radio network system.

35. A method as in claim 34 where the signal comprises an information element indicating that a Nl mode radio capability of the user equipment is disabled.

36. A method as in any one of claims 34-35 where the first core network entity is an evolved packet core network entity.

37. A method as in any one of claims 34-36 where the second radio network . system is a 5G radio network system and the second core network entity comprises a 5G network core, and where the signal indicates that the first radio access network entity should not handover the user equipment to the 5G radio network system.

38. An apparatus comprising: means for receiving a request for a handover by the apparatus regarding a user equipment coupled to the apparatus, where the apparatus comprises a first radio access network entity, and where the first radio access network entity is coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and means for preventing . the handover of the user equipment from the first radio access network entity to the second radio network system based, at least partially, upon a signal received by the first radio access network entity from the first core network entity of the first radio network system.

39. An apparatus as in claim 38 where the signal comprises an information element indicating that a N1 mode radio capability of the user equipment is disabled.

40. An apparatus as in any one of claims 38-39 where the first core network entity is an evolved packet corenetwork entity.

41. An apparatus as in any one of claims 38-40 where the second radio network system is a 5G radio network system and the second core network entity comprises a 5G network core, and where the signal indicates that the first radio access network entity should not handover the user equipment to the 5G radio network system.

42. A non-transitory program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, the operations comprising: determining receipt a request by a second radio access network entity for a handover of a user equipment coupled to a first radio access network entity, where the first and second radio access network entities are coupled to a first core network entity of a first radio network system, and where the user equipment is configured to be able to be used with both the first core network entity of the first radio network system or a different second radio network system having a different second core network entity; and receiving a signal by the second radio access network entity from at least one of the first radio access network entity or the first core network entity indicating that the second radio access network entity should not handover the user equipment to a radio access network entity of the second radio network system.