WO2016005002A1

WO2016005002A1 - Methods and apparatuses for bearer type signalling

Info

Publication number: WO2016005002A1
Application number: PCT/EP2014/064910
Authority: WO
Inventors: Woonhee Hwang; Tero Henttonen
Original assignee: Nokia Solutions And Networks Oy
Priority date: 2014-07-11
Filing date: 2014-07-11
Publication date: 2016-01-14

Abstract

Disclosed are methods and apparatuses for generating a bitmap comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; and signalling the bitmap as part of a radio bearer configuration.

Description

METHODS AND APPARATUSES FOR BEARER TYPE SIGNALLING

Field The present application relates to the configuration or modification of data resources.

Background

A communication system may be seen as a facility that enables communication sessions between two or more nodes such as fixed or mobile communication devices, access points such as nodes, access nodes, servers, hosts, machine type servers, routers, and so on. A communication system and compatible communicating devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. For example, the standards, specifications and related protocols may define the manner how communication devices shall communicate with the access points, how various aspects of the communications shall be implemented and how the devices and functionalities thereof shall be configured.

An example of cellular communication systems is an architecture that is being standardized by the 3rd Generation Partnership Project (3GPP). A recent development in this field is often referred to as the long-term evolution (LTE) or long-term evolution advanced (LTE advanced) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. In LTE access nodes providing the cells are commonly referred to as enhanced NodeBs (eNB). An eNB may provide coverage for an entire cell or similar radio service area.

A user may access the communication system by means of an appropriate communication device. A communication device of a user is often referred to as user device (UE), user device or terminal. A communication device is provided with an appropriate signal receiving and transmitting arrangement for enabling communications with other parties. In wireless systems a communication device typically provides a transceiver station that may communicate with another communication device such as e.g. a access node. A communication device such as a user device (UE) may access a carrier provided by a access node, and transmit and/or receive on the carrier.

Capacity of a communication system may be improved by providing network densification - increasing a number of network nodes and decreasing an average distance between user equipment and network nodes. One method of increasing densification of a network is to provide smaller nodes (for example low power nodes) under the control of more powerful macro nodes. The smaller nodes may provide the network with an increased traffic capacity while the macro nodes may provide service availability for the coverage area.

In dual connectivity, a user equipment may operate in a system having both master nodes and secondary nodes and may carry out simultaneous (dual) communication with a master and a secondary node. The functionality of the master and secondary nodes may be arranged in different ways, for example control signalling may be carried out through the master node while data signalling may be carried out through the secondary node and/or both master and secondary nodes. Therefore, uplink and downlink connectivity may be separated between the master and secondary node.

When a secondary node is added to the user equipment, data resource bearers are typically configured for that secondary access node and the user equipment. Signalling of such data bearers or modification thereto adds to the signalling overhead of the system.

According to a first aspect, there is provided a method comprising: generating a bitmap comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; and signalling the bitmap as part of a radio bearer configuration.

The dual connectivity type may be one of: a master cell group bearer; a secondary cell group bearer; and a split bearer. A position in the bitmap may correspond to an identity of the radio bearer. A bit corresponding to a first value in the bit map may indicate a first dual connectivity bearer type. A bit corresponding to a second bit value in the bit map may indicate a dual connectivity type of a radio bearer identified by a corresponding radio bearer identity to be a dual connectivity type referenced by an additional field . A first value of the additional field may indicate a second dual connectivity bearer type and a second value of the additional field may indicate a third dual connectivity bearer type. A bit corresponding to a second bit value in the bit map may indicate a second dual connectivity bearer type of a radio bearer identified by a corresponding radio bearer identity.

The first dual connectivity type may be a master cell group bearer. The second dual connectivity type may be a secondary cell group bearer and a third dual connectivity type may be a split bearer. The identity of the radio bearer may be an evolved packet service bearer identity.

The method may further comprise signalling the bitmap to a user equipment. The method may further comprise signalling the bitmap to a secondary access node. The method may further comprise: providing the functionality of a master access node to a user equipment and a secondary access node.

According to a second aspect, there may be provided an apparatus comprising at least one processor and at least one memory including computer program code for one or more programs, the at least one memory and the computer program code configures, with the at least one processor, to cause the apparatus to at least to carry out the steps of: generate a bitmap comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; and signal the bitmap as part of a radio bearer configuration.

According to an alternative second aspect, there may be provided an apparatus comprising means for: generating a bitmap comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; and signalling the bitmap as part of a radio bearer configuration.

A master access node may comprise the apparatus of the second aspect. The master access node may be further configured to carry out a dual connectivity with a user equipment and a secondary access node. The dual connectivity type may be one of: a master cell group bearer; a secondary cell group bearer; and a split bearer. A position in the bitmap may correspond to an identity of the radio bearer. A bit corresponding to a first value in the bit map may indicate a first dual connectivity bearer type. A bit corresponding 5 to a second bit value in the bit map may indicate a dual connectivity type of a radio bearer identified by a corresponding radio bearer identity to be a dual connectivity type referenced by an additional field . A first value of the additional field may indicate a second dual connectivity bearer type and a second value of the additional field may indicate a third dual connectivity bearer type. A bit i o corresponding to a second bit value in the bit map may indicate a second dual connectivity bearer type of a radio bearer identified by a corresponding radio bearer identity.

The first dual connectivity type may be a master cell group bearer. The second dual connectivity type may be a secondary cell group bearer and a third 15 dual connectivity type may be a split bearer. The identity of the radio bearer may be an evolved packet service bearer identity.

The apparatus may be further configured to signal the bitmap to a user equipment. The apparatus of claim may be further configured to: signal the bitmap to a secondary access node. The apparatus may be further configured to: 20 provide the functionality of a master access node to a user equipment and a secondary access node.

According to a third aspect, there is provided a computer program product for a computer, comprising software code portions for, when said product is run on the computer, performing the steps of: generating a bitmap comprising a mapping 25 between an identity of a radio bearer and a dual connectivity type of the radio bearer; and signalling the bitmap as part of a radio bearer configuration.

The dual connectivity type may be one of: a master cell group bearer; a secondary cell group bearer; and a split bearer. A position in the bitmap may correspond to an identity of the radio bearer. A bit corresponding to a first value in 30 the bit map may indicate a first dual connectivity bearer type. A bit corresponding to a second bit value in the bit map may indicate a dual connectivity type of a radio bearer identified by a corresponding radio bearer identity to be a dual connectivity type referenced by an additional field . A first value of the additional field may indicate a second dual connectivity bearer type and a second value of the additional field may indicate a third dual connectivity bearer type. A bit corresponding to a second bit value in the bit map may indicate a second dual connectivity bearer type of a radio bearer identified by a corresponding radio bearer identity.

The computer program product may be further configured to perform the step of: signalling the bitmap to a user equipment. The computer program product may be further configured to perform the step of: signalling the bitmap to a secondary access node. The computer program product may be further configured to perform the step of: providing the functionality of a master access node to a user equipment and a secondary access node.

According to a fourth aspect, there is provided a method comprising: receiving a bit map comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; determining a dual connectivity type for at least one radio bearer identified by the bit map; and update the radio bearer configuration for the at least one radio bearer.

Determining the dual connectivity type may comprise: reading a value from a position in the bitmap corresponding to the at least one radio bearer and determining the dual connectivity type in dependence on the value.

The method may further comprise determining that the value is a first value indicating a first dual connectivity bearer type. The method may further comprise determining that a bit corresponding to a second bit value in the bit map indicates a dual connectivity type of a radio bearer identified by a corresponding radio bearer identity to be a dual connectivity type referenced by a value of an additional field.

A first value of the additional field may indicate a second dual connectivity bearer type and a second value of the additional field indicates a third dual connectivity bearer type.

The method may further comprise determining that the value is a second bit value indicating a second dual connectivity bearer type of a radio bearer associated with a corresponding radio bearer identity.

The dual connectivity type may be one of: a master cell group bearer; a secondary cell group bearer; and a split bearer. A position in the bitmap may correspond to an identity of the radio bearer. The first dual connectivity type may be a master cell group bearer. The second dual connectivity type may be a secondary cell group bearer and a third dual connectivity type may be a split bearer. The identity of the radio bearer may be an evolved packet service bearer identity.

The method may further comprise: receiving the second bitmap. The method may further comprise: receiving the bitmap from a master access node.

According to a fifth aspect, there is provided an apparatus comprising at least one processor and at least one memory including computer program code for one or more programs, the at least one memory and the computer program code configures, with the at least one processor, to cause the apparatus to at least to carry out the steps of: receiving a bit map comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; determining a dual connectivity type for at least one radio bearer identified by the bit map; and update the radio bearer configuration for the at least one radio bearer.

According to a further aspect, there is provided an apparatus comprising means for carrying out the steps of: receiving a bit map comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; determining a dual connectivity type for at least one radio bearer identified by the bit map; and updating the radio bearer configuration for the at least one radio bearer.

The apparatus may be a secondary access node. The apparatus may be a user equipment. Determining the dual connectivity type may comprise: reading a value from a position in the bitmap corresponding to the at least one radio bearer and determining the dual connectivity type in dependence on the value.

The apparatus may be further configured to determine that the value is a first value indicating a first dual connectivity bearer type. The apparatus may be further configured to carry out the steps of determining that the value is a second value indicating a second dual connectivity bearer type. The apparatus may be further configured to carry out the steps of determining that the value is a second value indicating a dual connectivity type is indicated by a field of a second bit map. A first value of the field of the second bit map may indicate a second dual connectivity bearer type and a second value of the field of the second bit map may indicate a third dual connectivity bearer type.

The apparatus may be further configured to carry out the step of receiving the second bitmap. The apparatus may be further configured to carry out the steps of: receiving the bitmap from a master access node.

According to a sixth aspect, there is provided a computer program embodied on a computer-readable storage medium, the computer program comprising program code for controlling a process to execute a process, the process comprising: receiving a bit map comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; determining a dual connectivity type for at least one radio bearer identified by the bit map; and updating the radio bearer configuration for the at least one radio bearer.

According to a further aspect, there is provided a computer program product for a computer, comprising software code portions for, when said product is run on a computer, performing the steps of: receiving a bit map comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; determining a dual connectivity type for at least one radio bearer identified by the bit map; and updating the radio bearer configuration for the at least one radio bearer. Determining the dual connectivity type may comprise: reading a value from a position in the bitmap corresponding to the at least one radio bearer and determining the dual connectivity type in dependence on the value.

The computer program may be further configured to determine that the value is a first value indicating a first dual connectivity bearer type. The computer program may be further configured to carry out the steps of determining that the value is a second value indicating a second dual connectivity bearer type. The computer program may be further configured to carry out the steps of determining that the value is a second value indicating a dual connectivity type is indicated by a field of a second bit map. A first value of the field of the second bit map may indicate a second dual connectivity bearer type and a second value of the field of the second bit map may indicate a third dual connectivity bearer type.

The dual connectivity type may be one of: a master cell group bearer; a secondary cell group bearer; and a split bearer. A position in the bitmap may correspond to an identity of the radio bearer. The first dual connectivity type may be a master cell group bearer. The second dual connectivity type may be a secondary cell group bearer and a third dual connectivity type may be a split bearer. The identity of the radio bearer may be an evolved packet service bearer identity. The computer program may be further configured to carry out the step of receiving the second bitmap. The computer program may be further configured to carry out the steps of: receiving the bitmap from a master access node.

Brief description of drawings

Embodiments of the present application will now be described with reference to the following figures in which: Figure 1 is a schematic diagram showing an example of a network in which some embodiments may be implemented;

Figure 2 is a schematic diagram showing an example of a network architecture of some embodiments;

Figures 3a, 3b and 3c are schematic diagrams depicting the types of bearers available in dual connectivity;

Figure 4 is a signalling diagram depicting messaging between network nodes of embodiments;

Figure 5 is an example of a bit map message format for the configuration of a data bearer type; Figures 6a and 6b are two examples of bit maps in accordance with embodiments;

Figure 7a is a flow diagram depicting the method steps that may be carried out in some embodiments;

Figure 7b is a flow diagram depicting the method steps that may be carried out by a master access node in accordance with some embodiments; Figure 8a is a flow diagram depicting the method steps that may be carried out by a receiver in accordance with some embodiments;

Figure 8b is a flow diagram depicting a further example of the method steps that may be carried out by a receiver in accordance with some embodiments; Figure 9 shows an example of a telecommunications system in which embodiments may be implemented; and

Figure 10 is a schematic diagram showing an example of a user equipment that may be used in some embodiments;

Detailed description

Before explaining in detail the exemplifying embodiments, certain general principles of a wireless communication system and mobile communication devices are briefly explained with reference to Figures 1 to 3 to assist in understanding the technology underlying the described examples.

In a wireless communication system mobile communication devices or user equipment (UE) 102, 103, 104 are provided wireless access via at least one access node or similar wireless transmitting and/or receiving node or point. Access nodes are typically controlled by at least one appropriate controller apparatus, so as to enable operation thereof and management of mobile communication devices in communication with the access nodes. The controller apparatus may be part of the access node and/or provided by a separate entity such as a Radio Network Controller. In Figure 1 control apparatus 108 and 1 09 are shown to control the respective macro or master level access nodes 106 and 107. The control apparatus of a access node can be interconnected with other control entities. The control apparatus is typically provided with memory capacity and at least one data processor. The control apparatus and functions may be distributed between a plurality of control units. In some systems, the control apparatus may additionally or alternatively be provided in a radio network controller.

LTE systems may however be considered to have a so-called "flat" architecture, without the provision of RNCs; rather the (e)NB is in communication with a system architecture evolution gateway (SAE-GW) and a mobility management entity (MME), which entities may also be pooled meaning that a plurality of these nodes may serve a plurality (set) of (e)NBs. Each UE is served by only one MME and/or S-GW at a time and the (e)NB keeps track of current association. SAE-GW is a "high-level" user plane core network element in LTE, which may consist of the S-GW and the P-GW (serving gateway and packet data network gateway, respectively). The functionalities of the S-GW and P-GW are separated and they are not required to be co-located.

In Figure 1 the master access node 106 is shown as connected to a wider communications network 1 13 via gateway 1 12a and the master access node 107 is shown as connected to a wider communications network 1 13 via gateway 1 1 2b. A further gateway function may be provided to connect to another network in some examples. The gateway 1 1 2b may be coupled to provide user plane data to and from the wider communications network. A further entity such a mobility management entity may be provided to provide control plane data to and from the wider communications network 1 13.

The smaller or secondary access nodes 1 10 and 105 may also be connected to the network 1 13, for example via the gateways 1 12a and 1 12b and/or via the controllers 108, 109 of the macro level stations 106, 107. In the example, secondary access node 105 may be connected to the network via the controller 1 08 of the master access node 106 and/or may be connected via the gateway 1 1 2a. The secondary access node 1 10 may be connected to the network via the controller 109 of the master access node 107 and/or may be connected via the gateway 1 12b. The secondary access nodes may for example be provided by a pico cell, a micro cell, and/or the like. It will be appreciated that the secondary access node 105 may for example be coupled to the gateway 1 12a via the controller 1 08 or directly to the gateway 1 12a. The communication system may support the user equipment 1 02 being in simultaneous communication with the master access node 106 and the second access node 1 05. Similarly the use equipment 104 may be supported being in simultaneous communication with the secondary access node 1 10 and the master access node 107. The communication may thus support dual connectivity. Figure 2 shows an example of a bearer service architecture of a network in which embodiments may be implemented. Figure 2 shows a UE 102, an access node, for example an eNB 106, a serving gateway (S-GW) 1 12a, a packet data network (PDN) Gateway 201 and peer entity 202. There is an evolved UMTS Terrestrial Radio Access network between the UE 102 and the eNB 1 06, an evolved packet core (EPC) between the eNB and the S-GW 1 12a and PDN-GW 201 and the peer entity 202 is on the internet. In this example, the end-to-end service 203 represents the data bearers between the UE 102 and the peer entity 202.

The end to end service comprises evolved packet service (EPS) bearers

204 between the UE 102 and the P-GW 201 and external bearers 205 between the P-GW 201 and the peer entity 202. The EPS bearer 204 comprises E-RAB bearers 206 between the UE 102 and the S-GW 1 12a and S5/S8 bearers 207 between the S-GW 1 1 2a and the PDN-GW 201 . The E-RAB comprises radio bearers 208 between the UE 102 and the eNB 106 and S1 bearers 209 between the eNB 106 and the S-GW 1 12a.

There may be a radio interface between the UE 102 and the eNB 106, an S1 interface (user plane data) between the eNB 106 and the S-GW 1 12a, an S5/S8 interface between the S-GW 1 12a and the PDN-GW 201 and a Gi interface between the PDN-GW 201 and the peer entity 202.

It will be appreciated that the eNB 1 06 while being exemplified as a MeNB, may also be a SeNB in some embodiments. It will also be appreciated that figure 2 is an example of a telecommunications network only and the present disclosure may be applicable to other communication systems.

Referring now to the radio bearers 208 of figure 2, it will be appreciated that in dual connectivity, the radio bearers or data radio bearers (DRBs) may be of different types depending on the type of dual connectivity being carried out. Figures 3A to C show an example of the different types of radio bearers implemented in dual connectivity.

The figures 3A to C depict a gateway 1 12, a mobility management entity

1 1 5, a master access node 1 06, a secondary access node 1 05 and a user equipment 102. It will be appreciated that in these examples, the master access node 106 may be configured to carry control plane data 304 to and from the user equipment 102 and control plane data 301 to and from the mobility management entity 1 1 5. Additionally the master access node 106 may be configured to carry control plane data 303 to and from the secondary access node 105. The control plane data 304 between the user equipment and the MeNB in some embodiments may be radio resource control (RRC) data. It will be appreciated that in some embodiments, there may also be non-access stratum (NAS) data being transferred between the user equipment and the MME but this is not shown. In some embodiments, at least part of the control plane data 301 between the MeNB and the MME 1 15 may be also transferred between the MeNB and the SeNB.

In this case, there may be a S1 -MME interface between the master access node 1 06 and the mobility management entity 1 15 and an X2-C interface between the master access node 1 06 and the secondary access node 105.

In addition to the control plane data, user plane data 302 may be carried between the gateway 1 12 and the user equipment. The path taken by the user plane data 302 is dependent on the type of bearer implemented. Figures 3a, 3b and 3c depicted the path taken by the user data for three types of bearers. Figure 3a shows master cell group (MCG) bearers, figure 3b shows secondary cell group (SCG) bearers and figure 3c shows split bearers.

Figure 3a shows the case where there are master access node (MeNB) or master cell group (MCG) bearers. In this case, control plane data 301 is transferred between the MeNB 1 06 and a control entity such as a mobility management entity (MME) 1 15 and control plane data 304 is transferred between the MeNB 106 and the user equipment 102. Control data 303 may be transferred between the MeNB 1 06 and the SeNB 105. The user plane data 302 may be provided between a network entity such as a gateway 1 12 and the MeNB 106 and between the MeNB 106 and the user equipment 102. Thus the bearers carrying the user plane data are MCG bearers.

Figure 3b shows a case where the bearers are secondary access node (SeNB) or secondary cell group (SCG) 1 05 bearers. Similarly to figure 3a, control plane data 301 is transferred between the MeNB 1 06 and the MME 1 1 5 and control plane data 304 is transferred between the MeNB 106 and the user equipment 102. Control plane data 303 is transferred between the MeNB 106 and the SeNB 105. User plane data 302 is shown as being provided between the gateway 1 12 and the SeNB 105 and the SeNB 1 05 and the user equipment 1 02. For SCG bearers, a user plane is directly connected between a gateway and a SeNB. It can be seen that in this case, the bearers for carrying user plane data to and from the user equipment are SCG bearers.

Figure 3c shows a case where the bearers are split bearers. Similarly to figures 3a and b, control plane data 301 is transferred between the MeNB 106 and the MME 1 1 5 and control plane data 304 is transferred between the MeNB 106 and the user equipment 102. Control plane data 303 is transferred between the MeNB 106 and the SeNB 1 05. User plane data 302 is shown as being provided between the gateway 1 12 and the MeNB 106, the MeNB 106 and the SeNB 105, the MeNB 106 and the user equipment 102 and the SeNB 105 and the user equipment 102. It can be seen that in this case, the bearers for carrying user plane data to and from the user equipment are split between the MeNB 106 (MCG) and the SeNB 1 05 (SCG).

It will be appreciated that while the MME 1 15 and gateway 1 12 have been depicted separately, in some embodiments the MME 1 15 and the gateway 1 12 may be co-located at a single entity. It will also be appreciated that while figures 3a to 3c have been shown relating to a long term evolution (LTE) system, in some embodiments dual connectivity may not be restricted to such systems. For example dual connectivity may be implemented in conjunction with future modifications or evolutions of LTE.

In order for a UE to transfer user plane data between the UE and an access node such as a MeNB and/or SeNB, data resource bearers are configured between the UE and the access node to carry the user data. The data radio bearers may be configured for example when or after an access node is added to the UE for communication, for example when a SeNB is added to the UE. The data radio bearers may also be modified or released after being configured.

Figure 4 is a signalling flow diagram that shows an example of the signalling flow when a SeNB is added to a UE as well as the modification of the data radio bearers. It will be appreciated that while the example of figure 4 shows the data radio bearers being configured on the addition of the SeNB, the configuration of the data radio bearers may occur independently to this. Figure 4 shows the messaging flow between a UE 102, a MeNB 106 and a SeNB 105. At step 401 , a radio resource control (RRC) connection is established between a MeNB 106 and the UE 102. Once this control connection is established between the UE 1 02 and the MeNB 1 06, the MeNB 106 may configure data radio bearers for the UE 1 02. In this example, the MeNB configures the data radio bearers (DRBs) for the SeNB 1 05 however it will be appreciated that the MeNB 106 may provide the UE 102 with a DRB configuration for communication with the MeNB 106 instead or as well.

At step 402, the MeNB 106 provides a SeNB Addition or Modification message to the SeNB 105. The message 402 comprise configuration for dual connectivity with the UE 1 02. In this case, the message is providing a dual connectivity configuration for the SeNB 1 05 as the SeNB 105 has not yet been added to the UE 102, however it will be appreciated that the message in some cases may refer only to parameters between the UE 102 and the SeNB 105 that are to be modified. The dual connectivity configuration information in the message 402 may also comprise DRB configuration information.

The SeNB 105 may receive the message 402 and carry out or store the configuration information contained therein. The SeNB 105 may respond to the message 402 with a response message 403. This message may confirm to the MeNB 106 that the SeNB is configured and ready for dual connectivity as well as an indication of resources provided by the SeNB 105 that may be used by the UE to perform the dual connectivity.

At step 404, the MeNB 106 may provide configuration information to the UE 102 to allow it to carry out dual connectivity with the SeNB 105. In this case the MeNB 1 06 may provide a radio resource control (RRC) reconfiguration request 404 to the UE 102. The RRC reconfiguration request 404 may comprise configuration information for the DRBs between the UE 102 and the SeNB and/or the MeNB1 06.

At step 405, the UE 102 may respond to the message 404 with a RRC reconfiguration response 405. If the procedure is a SeNB addition procedure, the UE 1 02 may carry out a random access procedure towards the SeNB 1 05 to allow communication of user data between the UE and the SeNB. It will be appreciated that steps 401 to 406 depict the case where a SeNB 105 is being added to the UE 102 however configuration or modification of the DRBs may be carried out independently of such a procedure. Message 407 to 410 show a case where a modification of some of the configuration parameters is carried out.

At step 407 the MeNB 106 may provide modified configuration parameters, for example DRB configuration to the SeNB 105. The SeNB 105 may respond with a modification response at 408. The MeNB 106 may also provide the modified configuration information to the UE 1 02 in a RRC reconfiguration message at step 409. The UE 102 may respond to the request at step 410.

It will be appreciated that figure 4 gives an example of a manner in which DRB configuration information may be provided to the SeNB and the UE by the MeNB. The configuration of the DRBs may include a type of data bearer. Figures 3A to C show three types of radio bearers, namely MCG bearers, SCG bearers and split-bearers. During the configuration of the DRBs for a UE and a SeNB, the type of data bearer should be configured.

In some systems, each radio bearer (DRB) may be indexed with a radio bearer identity during the radio bearer configuration. When a modification of the radio bearer occurs, the radio bearer identity is used to identify the existing bearer in the modification signaling. For example, if a SeNB modification message is sent where a bearer type is being modified, the message comprises the identity of the DRB and a type of the bearer. Currently the DRB identity is 32 bits long and the identity is sent with the bearer type in order to identify the bearer to the UE and/or SeNB.

The configuration and release of dual connectivity may require defining operations for the reconfiguration of DRB entities for dual connectivity. In some systems modification to the bearer type is done by explicitly identifying the bearer in the message (using bearer identity) and providing a bearer configuration which includes a bearer type. This may be done on a bearer by bearer basis. Thus the signaling of a modified bearer type may incur a large overhead.

In embodiments of the present disclosure bearer type may be indicated by signaling a bitmap comprising a mapping between a bearer identity and a bearer type indicated by a bit value. The identity may be an evolved packet service (EPS) identity of the bearer. On receipt of the bitmap, a UE or SeNB may apply any modifications to the bearer type.

In embodiments, a bearer identity may be associated with a bearer type (for example a MCG bearer, SCG bearer and/or split bearers). The bearer identity may further be associated with a configuration of the bearer. In some examples, if configuration parameters of a bearer are to be modified, a message containing bearer specific configuration may be sent comprising a bearer identity and the configuration parameters. The configuration parameters may be modified on a bearer by bearer basis. However, if a type of the bearers is changed, for example a number of bearers are modified from being SCG bearers to MCG bearers, in embodiments a bitmap mapping a bearer identity to a bearer type for a plurality of bearers may be signaled to provide the modification. The bearer type may for example be omitted from a per-bearer specific configuration in the message in some embodiments, in other embodiments the bearer type may be configured in a per-bearer specific configuration in the message and also through a bitmap.

In some embodiments, the bitmap may be transmitted as part of a configuration message - for example as an information element in such a message. In some examples, the configuration message may be a radio resource control (RRC) connection reconfiguration message. It will be appreciated that a per-bearer configuration and bearer identity may be transmitted in a different RRC connection reconfiguration message when other parameters of the bearer configuration are being changed and/or set-up.

Figure 5 shows an example of a bitmap associating a bearer identity with a bearer type. It will be appreciated that in some embodiments, when a MeNB updates or configures a bearer type at a UE or SeNB, the MeNB may send such a bitmap as that shown in figure 5 to show the bearer type for the bearer identities.

Figure 5 shows an example of a system with 16 bearers where each bearer has an associated bearer identity. In the example of figure 5, the bearer identity is a evolved packet service (EPS) bearer identity. In the example of figure 5 the individual EPS bearer identities are shown as "EPS n", where n is a number ranging from 0 to 15.

It will however be appreciated that this is by way of example only and the notation may vary. It will also be appreciated that 16 bearers is by way of example only. For example in some systems the maximum number of bearers provided for a user may be 8, in which case in some examples the bitmap may be restricted to 8 bearers. In embodiments the number of bearers in the bitmap may correspond to the number of bearers in the system. In other embodiments the number of bearers may be more or less than the number of bearers for the UE. For example less than the available number of bearers may be signalled or additional information may be signalled in the bitmap mapped to for example a dummy bearer. Figure 5 shows a bitmap 500 comprising 1 6 bits where each bit corresponds to a bearer identity. In this example the position of a bit in the bitmap corresponds to a bearer identity with for example the fourth bit in the bit map corresponding to a bearer identity EPS 3 and a fifteenth bit in the bitmap corresponding to a bearer identity EPS 14 etc.

The bitmap 500 may indicate whether a bearer is a first type of bearer or a second type of bearer. For example if a first bearer is a MCG bearer, the bit in the bitmap corresponding to the identity of the first bearer will be a logical Ό'. If the bearer is not an MCG bearer, for example a second type of bearer, the bit value in the bitmap corresponding to the identity of the first bearer will be a logical '1 ' indicating that the bearer is a second type of bearer.

In some examples there may be more than two types of bearers. In the above examples there are three dual connectivity bearers- for example MCG, SCG and split bearers. In this case, an additional field 502 may be signalled to the UE and/or SeNB. The additional field may be used to identify a bearer type indicated by a second bit value in the bitmap. For example, a first bit value in the bitmap 500, for example logical Ό', may indicate that the bearer is of a first type. A second bit value in the bitmap 500, for example a logical Ί ', may indicate that the bearer type is of a type referenced or identified by a bit value in the additional field 502. In this example, the logical '1 ' in the bitmap may indicate the type of bearer of the associated bearer identity, but that type of bearer is defined or interpreted based on a value in the additional field.

The additional field may hold a value (for example a bit) that defines a type of bearer -for example a MCG, SCG and/or split bearer. When one or more bearer identities are associated with a second bit value in the bit map 500, the bearer type indicated by the second bit value is determined by the value of the additional field. For example, in the bit map 500 some of bit values may be of a first value indicating that the bearers associated with each of those bit values are of a first type of bearer. Other bit values may be of a second value indicating that the bearers associated with the other bit values are of a type indicated by the additional field. If the additional field is of a first value (not necessarily the same as the first value of the bit values in the bit map), the bearers associated with the other bit value are of a second type. If the additional field is of a second value (not necessarily the same as the second value of the bit values in the bit map), the bearers associated with the other bit value are of a third type. In some examples the additional field may be a second bit map. In some embodiments the additional field may be an information element. The additional field may in some examples be provided as part as a configuration message.

In some embodiments the additional field may be signalled alongside the bitmap 500, for example as part of the bitmap or with a message accompanying the signalling of the bit map. In another example, the additional field may be signalled separately, for example during a dual connectivity setup or other procedure.

While a logical Ό' and logical '1 ' has been given by example, it will be appreciated that the setting of these values may be a design choice and may differ in implementations and embodiments are not restricted as such. It will be appreciated that a field in the bit map may be set to a bit value where respective bit values may reference respective bearer types. A certain bit value in the bitmap may reference a bearer type as indicated by a value of an additional field.

Figures 6a and 6b give two examples of bit maps that may be signalled to a UE and/or SeNB to indicate a bearer type. In the example of figure 6a, an additional field 502 is set to a logical '0' indicating that bits referencing the additional field represent split bearers. The bits in the bitmap set to '1 ' reference the additional field and thus the bearer identities associated with these bits represent split bearers. In this example the bit map comprises bits 0 to 16 and bits 0, 2 and 3 indicate split bearers. The remaining bits 1 , 4 to 16 are set to '0' indicating MCG bearers. Thus it can be determined that the bearer identities associated with bits 0, 2 and 3 identify split bearers and the bearer identities associated with bits 1 and 4 to 16 identify MCG bearers. In the example of figure 6b, an additional field 502 is set to a logical '1 ' indicating that bits referencing the additional field represent SCG bearers. The bits in the bit-map set to '1 ' reference the additional field and thus the bearer identities associated with these bits represent SCG bearers. In this example the bit map 5 comprises bits 0 to 16 and bits 0, 2 and 4 indicate SCG bearers. The remaining bits 1 , 3 and 5 to 16 are set to Ό' indicating MCG bearers for the bearer identities associate with those bits.

Figures 5, 6a and 6b have shown examples of a bit map that may be signalled to a UE and/or a SeNB to indicate a bearer type for the bearer identities i o associated with the bit map. When it is determined that a bearer type has been modified, a MeNB may generate a bit map mapping bearer identities to respective types of bearers.

Figure 7a is a flow diagram depicting the method steps carried out be a

MeNB in accordance with some embodiments. It will be appreciated that in this 15 example the method steps are carried out by the MeNB however in other examples the bit map may be provided to the MeNB by another entity such as a

MME 1 15 or gateway 1 12.

At step 701 , a mapping between a radio bearer identity and a radio bearer type may be made. In some embodiments the mapping may be made by a MeNB 20 106. In other embodiments, the mapping may be made by a higher network entity such as a MME or a gateway and provided to the MeNB for signalling to a UE and/or SeNB.

At step 702, the mapping may be signalled to a UE and/or SeNB. The mapping may be signalling as part of a configuration of a radio bearer. The 25 mapping may be signalling in response to a determination that a bearer type for a radio bearer has been modified or changed. In some cases a bearer may be released and may be removed from the mapping. In some embodiments, the mapping may correspond to the bit maps of figures 5, 6a and 6b.

Figure 7b is a flow diagram depicting example method steps for generating 30 the mapping. It will be appreciated that in this example steps 703 and 704 of figure 7b may correspond to step 701 of figure 7a.

At step 703 a bit map may be determined by associating a bearer identity with a position in the bit map. It will be appreciated that the UE and/or SeNB may be aware of this mapping and thus the bearer identity need not be explicitly signalled to the UE and/or SeNB. At step 704 each bit may be set to a value indicating the type of the bearer identified by the associated bearer identity. The bit value may correspond to a bearer type directly or, in the case that there are more than two type of bearers, may reference an additional field. The additional field 502 may be set to indicate a type of bearer associated with the bits referencing the additional field. At step 705, the bit map may be signalled to a further entity for example a UE and/or SeNB. In some examples, the bit map may be signalled as part of a configuration or modification procedure.

Figure 8a is a flow diagram depicting the method steps associated with a receiver of the mapping from the MeNB or access node. It will be appreciated that in some embodiments, the mapping may be received by a UE, a SeNB or by both the UE and SeNB.

At step 801 of figure 8a, a mapping between a bearer identity and bearer type is received. At step 802 a type of bearer for respective bearers identified by the mapping is determined. At step 803, the bearer type is updated for the bearers identified by the mapping. The receiver of the mapping may then operate in accordance with the bearer type.

Figure 8b shows more detailed method steps that may be carried out by a receiver of the mapping. It will be appreciated that in the figure 8b, the steps 804 and 805 may correspond to step 802 of figure 8a. It will be appreciated that the method of figure 8b may be carried out for one or more of the bearer identities mapped by mapping.

At step 804, a bit value corresponding to a first bearer identity is read from the mapping. The receiver may determine the type of bearer indicated by that value and thus the type of the bearer identified by the first bearer identity at step 805. In some embodiments, the value will directly identify the type of bearer. For example a bit value of Ό' may identify a MCG bearer. In other embodiments, the value may indirectly identify the bearer by referencing an additional field in the received bit map. If the value references the additional field, the method may include determining that the value references the additional field, reading the value of the additional field and determining a bearer type indicated by the additional field value. At step 806, a bearer type parameter or field for the bearer identified by the first bearer identity may be updated. The receiver may then operate in accordance with the updated bearer type. It will be appreciated that the method steps may be repeated for one or more of the bearers identified in the mapping.

5

It will be appreciate that the steps/points, signalling messages and related functions described above in Figures 7a, 7b, 8a and 8b are in no absolute chronological order, and some of the steps/points may be performed simultaneously or in an order differing from the given one. Other functions may i o also be executed between the steps/points or within the steps/points and other signalling messages sent between the illustrated messages. Some of the steps/points or part of the steps/points may also be left out or replaced by a corresponding step/point or part of the step/point.

It will be appreciated that in the foregoing the receiver of the bit map is

15 described as being aware of the mapping between the bearer identities and a position in the bit map. The receiver may additionally be which bearer types are indicated by which values. In some embodiments, the receiver (a UE and/or SeNB) may be preconfigured with such information. In other embodiments, the mapping and bearer type correspondence information may be provided in an

20 earlier configuration message. For example the information may be provided during a dual connectivity setup procedure.

It will be appreciated that in the foregoing the additional field has been described as being signalled alongside the bitmap, for example part of the bit map, or having previously been signalled to the UE and/or SeNB. The additional field is

25 also described as holding a value indicating a bearer type for bearer identities referencing the additional field. In further embodiments the additional field may be a second bit map and may be provided to the UE and/or SeNB through separate signalling to the mapping.

It will be appreciated that the foregoing has referred to a master access

30 node (MeNB) and a secondary access node (SeNB). It will be appreciated that each access node or access node may support a number of cells. In the case of the secondary access node these cells are called secondary cells (SCells) and form part of a secondary cell group (SCG). Similarly the MeNB may support a primary cell and secondary cells (SCells) forming part of a master cell group.

One of the secondary cells in SCG is a primary secondary cell (PSCell) and may carry out extended functionality to the secondary cells of the SCG. While the secondary cells are provided for the transmission and reception of the user data, the PSCell may carry control functions for the SCG. For example configuration information such as the bearer type bit map may be provided to the PSCell and the PSCell may generate the responses to such messaging. It will be appreciated that in the foregoing messaging is described as being to and from the SeNB, however in some embodiments, this messaging may be towards the PSCell. It will be appreciated that the UE may be in dual connectivity with one or more of the SCells and may communicate with the PSCell when it comes to the random access procedure.

A possible communication device will now be described in more detail with reference to Figure 9 showing a schematic, partially sectioned view of a communication device 102. It will be appreciated that such a communication may be configured to communicate with the access nodes for example the MeNB and SeNB in embodiment. The communication device may receive a mapping between a radio bearer identity and a radio bearer type and may be configured to carry out any of the method steps as described with reference to figures 8a and/or 8b. The communication device may further be configured to carry out any of the method steps or functionality of a user equipment 102 as described in embodiments of the foregoing.

Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples include a mobile station (MS) or mobile device such as a mobile phone or what is known as a 'smart phone', a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, or any combinations of these or the like. A communications device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services include two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content include downloads, television and radio programs, videos, advertisements, various alerts and other information.

The device 102 may receive signals over an air or radio interface 807 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 9 transceiver apparatus is designated schematically by block 806. The transceiver apparatus 906 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the device.

A device is typically provided with at least one data processing entity 901 , at least one memory 902 and other possible components 903 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 904. The user may control the operation of the device by means of a suitable user interface such as key pad 905, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 908, a speaker and a microphone can be also provided. Furthermore, a communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

The device in one example may correspond to the UE 102 of embodiments and may be configured to carry out any of the method steps or functionality associated therewith. For example, in one example, the device may be configured to carry out any of the method steps of figures 8a and 8b when the mapping is sent to the UE. For example, the at least one memory may include computer program code for one or more programs, the at least one memory and the computer program code may be configured to, with the at least one processor, to cause the apparatus to at least to carry out the steps of: receiving a bit map comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; determining a dual connectivity type for at least one radio bearer identified by the bit map; and update the radio bearer configuration for the at least one radio bearer. The control apparatus may comprise means for carrying out the steps of: receiving a bit map comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; determining a dual connectivity type for at least one radio bearer identified by the bit map; and update the radio bearer configuration for the at least one radio bearer.

The communication devices 102, 103, 104 may access the communication system based on various access techniques, such as code division multiple access (CDMA), or wideband CDMA (WCDMA). Other non-limiting examples comprise time division multiple access (TDMA), frequency division multiple access (FDMA) and various schemes thereof such as the interleaved frequency division multiple access (IFDMA), single carrier frequency division multiple access (SC- FDMA) and orthogonal frequency division multiple access (OFDMA), space division multiple access (SDMA) and so on.

An example of wireless communication systems are architectures standardized by the 3rd Generation Partnership Project (3GPP). A latest 3GPP based development is often referred to as the long term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. The various development stages of the 3GPP specifications are referred to as releases. More recent developments of the LTE are often referred to as LTE Advanced (LTE-A). The LTE employs a mobile architecture known as the Evolved Universal Terrestrial Radio Access Network (E-UTRAN). Access nodes of such systems are known as evolved or enhanced Node Bs (eNBs) and provide E- UTRAN features such as user plane Radio Link Control/Medium Access Control/Physical layer protocol (RLC/M AC/PHY) and control plane Radio Resource Control (RRC) protocol terminations towards the communication devices. Other examples of radio access system include those provided by access nodes of systems that are based on technologies such as wireless local area network (WLAN) and/or WiMax (Worldwide Interoperability for Microwave Access).

Figure 10 shows an example of a control apparatus. The control apparatus comprises at least one memory 1 1 , at least one data processing unit 12, 13 and an input/output interface 14. Via the interface the control apparatus can be coupled to receive and/or transmit data. For example the control apparatus can be configured to execute an appropriate software code to provide the control functions. The control apparatus may be provided in one or more of master access node, a secondary access node and any other suitable control entity.

It will be appreciated that in one example the control access may correspond to the MeNB 106 of embodiments and may be configured to carry out any of the method steps or functionality associated therewith. For example, in one example, the control apparatus may be configured to carry out any of the method steps of figures 7a and 7b. In this case, the control apparatus may be a base station, eNode B or any suitable apparatus capable to carry out processes described above in relation to Figure 7a and 7b.

The at least one memory may include computer program code for one or more programs, the at least one memory and the computer program code may be configured to, with the at least one processor, to cause the apparatus to at least to carry out the steps of: generate a bitmap comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; and signal the bitmap as part of a radio bearer configuration. The control apparatus may further comprise means for: generating a bitmap comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; and signalling the bitmap as part of a radio bearer configuration.

In another example the control apparatus may correspond to the SeNB 105 of embodiments and may be configured to carry out any of the method steps or functionality associated therewith. For example, in one example, the control apparatus may be configured to carry out any of the method steps of figures 8a and 8b when the mapping is sent to the SeNB. In this case, the control apparatus may be a base station, eNode B or any suitable apparatus capable to carry out processes described above in relation to Figure 8a and 8b. For example, the at least one memory may include computer program code for one or more programs, the at least one memory and the computer program code may be configured to, with the at least one processor, to cause the apparatus to at least to carry out the steps of: receiving a bit map comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; determining a dual connectivity type for at least one radio bearer identified by the bit map; and update the radio bearer configuration for the at least one radio bearer. The control apparatus may comprise means for carrying out the steps of: receiving a bit map comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; determining a dual connectivity type for at least one radio bearer identified by the bit map; and update the radio bearer configuration for the at least one radio bearer.

It is noted herein that while the above describes exemplifying embodiments of the invention, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

It will be appreciated while the foregoing describes bearers, in some embodiments these may be data resource bearers (DRB) and may be between an access node or base station and a user equipment. It will be appreciated that while the foregoing uses the term access node, it will be appreciated that the access node may be a network node to provide access to an user equipment to a network. The access node may be a node B, eNode B and/or a base transceiver station in some embodiments. Some embodiments have been described in relation to LTE in which case the access node will be an eNode B.

It will be appreciated that while the foregoing uses the term user equipment, it will be appreciated that the user equipment may be any communication device for accesses a network. A communication device can be understood as a device provided with appropriate communication and control capabilities for enabling use thereof for communication with others parties. The communication may comprise, for example, communication of voice, electronic mail (email), text messages, data, multimedia and so on. A communication device typically enables a user of the device to receive and transmit communication via a communication system and can thus be used for accessing various service applications. Some examples of user devices are a mobile station (mobile phone), smartphone, personal digital assistant (PDA), handset, device using a wireless modem (alarm or measurement device, etc.), laptop and/or touch screen computer, tablet, game console, notebook, and multimedia device. It should be appreciated that a user device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network.

The required data processing apparatus and functions of a access node apparatus, a communication device or user equipment and any other appropriate station may be provided by means of one or more data processors. The described functions at each end may be provided by separate processors or by an integrated processor. The data processors 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), application specific integrated circuits (ASIC), gate level circuits and processors based on multi core processor architecture, as non-limiting examples. The data processing may be distributed across several data processing modules. A data processor may be provided by means of, for example, at least one chip. Appropriate memory capacity can also be provided in the relevant devices. The memory or memories 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, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects of the invention may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

Some embodiments may be implemented by computer software executable by a data processor of the communication device, such as in the processor entity, or by hardware, or by a combination of software and hardware.

The apparatus may be, include or be associated with at least one software application, module, unit or entity configured as arithmetic operation, or as a program (including an added or updated software routine), executed by at least one operation processor. Programs, also called program products or computer programs, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they include program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments disclosed by means of Figures 7a, 7b or 8a and 8b. The one or more computer-executable components may be at least one software code or portions of it. In one example the functionality of the MeNB may be implemented as a computer program embodied on a computer-readable storage medium. The computer program may comprise program code for controlling a process to execute a process or method steps carried out by the MeNB, for example the method steps of figures 7a and/or 7b. In another example the functionality of the SeNB and/or UE may be implemented as a computer program embodied on a computer-readable storage medium. The computer program may comprise program code for controlling a process to execute a process or method steps carried out by the SeNB and/or UE, for example the method steps of figures 8a and/or 8b. Modifications and configurations required for implementing functionality of an embodiment may be performed as routines, which may be implemented as added or updated software routines, application circuits (ASIC) and/or programmable circuits. Further, software routines may be downloaded into an apparatus. The apparatus, such as a node device, or a corresponding component, may be configured as a computer or a microprocessor, such as single-chip computer element, or as a chipset, including at least a memory for providing storage capacity used for arithmetic operation and an operation processor for executing the arithmetic operation. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers. The computer readable medium or computer readable storage medium may be a non-transitory medium.

The applicant draws attention to the fact that the present disclosure may include any feature or combination of features disclosed herein either implicitly or explicitly or any generalisation thereof, without limitation to the scope of any definitions set out above. In addition to the modifications explicitly mentioned above, it will be evident to a person skilled in the art that various other modifications of the described embodiment may be made within the scope of the invention.

Claims

Claims:

1 . A method comprising: generating a bitmap comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; and signalling the bitmap as part of a radio bearer configuration.

2. The method of claim 1 wherein the dual connectivity type is one of: a master cell group bearer; a secondary cell group bearer; and a split bearer.

3. The method of claim 1 wherein a position in the bitmap corresponds to an identity of the radio bearer.

4. The method of claim 1 wherein a bit corresponding to a first bit value in the bit map indicates a first dual connectivity bearer type of a radio bearer identified by a corresponding radio bearer identity.

5. The method of claim 4 wherein a bit corresponding to a second bit value in the bit map indicates a dual connectivity type of a radio bearer identified by a corresponding radio bearer identity to be a dual connectivity type referenced by an additional field.

6. The method of claim 5 wherein a first value of the additional field indicates a second dual connectivity bearer type and a second value of the additional field indicates a third dual connectivity bearer type.

5 7. The method of claim 4 wherein a bit corresponding to a second bit value in the bit map indicates a second dual connectivity bearer type of a radio bearer identified by a corresponding radio bearer identity.

8. The method of claim 1 wherein the identity of the radio bearer is an evolved i o packet service bearer identity.

9. An apparatus comprising at least one processor and at least one memory including computer program code for one or more programs, the at least one memory and the computer program code configured, with the at least one processor, to cause the apparatus to at least to carry out the method according to

15 any one of claims 1 to 8.

10. An apparatus comprising means for carrying out the method according to any one of claims 1 to 8.

20 1 1 . A computer program product for a computer, comprising software code portions for performing the steps of any of claims 1 to 8, when said product is run on the computer.

12. A computer program embodied on a computer-readable storage medium, the 25 computer program comprising program code for controlling a processor to execute a process, the process comprising: generating a bitmap comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; and signalling the bitmap as part of a radio bearer configuration.

5 13. A method comprising: receiving a bit map comprising a mapping between an identity of a radio bearer and a dual connectivity type of the radio bearer; determining a dual connectivity type for at least one radio bearer identified by the bit map; and i o update the radio bearer configuration for the at least one radio bearer.

14. The method of claim 13 wherein determining the dual connectivity type comprises: reading a value from a position in the bitmap corresponding to the at least 15 one radio bearer and determining the dual connectivity type in dependence on the value.

15. The method of claim 14 further comprising determining that the value is a first bit value indicating a first dual connectivity bearer type of a radio bearer

20 associated with a corresponding radio bearer identity .

16. The method of claim 15 further comprising determining that a bit corresponding to a second bit value in the bit map indicates a dual connectivity type of a radio bearer identified by a corresponding radio bearer identity to be a

25 dual connectivity type referenced by a value of an additional field.

17. The method of claim 16 wherein a first value of the additional field indicates a second dual connectivity bearer type and a second value of the additional field indicates a third dual connectivity bearer type.

18. The method of claim 15 further comprising determining that the value is a second bit value indicating a second dual connectivity bearer type of a radio bearer associated with a corresponding radio bearer identity.

19. An apparatus comprising at least one processor and at least one memory including computer program code for one or more programs, the at least one memory and the computer program code configured, with the at least one processor, to cause the apparatus to at least to carry out the method according to any one of claims 13 to 18.

20. An apparatus comprising means for carrying out the method according to any one of claims 13 to 18.

21 . A computer program product for a computer, comprising software code portions for performing the steps of any of claims 13 to 18, when said product is run on the computer.

22. A computer program embodied on a computer-readable storage medium, the computer program comprising program code for controlling a processor to execute a process, the process comprising: receiving a bit map comprising a mapping between an identity of a radio and a dual connectivity type of the radio bearer; determining a dual connectivity type for at least one radio bearer identified bit map; and

updating the radio bearer configuration for the at least one radio bearer.