METHODS AND NETWORK NODES FOR HANDLING HANDOVER OF A USER EQUIPMENT

Disclosed is a method performed by a serving network node of a wireless communication network, the serving network node serving a UE, the serving network node handling a serving cell. The method comprises determining, based on capabilities of the UE, on configuration parameters of neighboring cells and the serving cell as well as on channel quality of signals received by the UE from network nodes handling the neighboring cells as well as on channel quality of signals received by the UE from the serving network node, a primary cell and at least one secondary cell for the UE. The method further comprises, when the determined primary cell is handled by a target network node, which is different from the serving network node, sending a handover message towards the target network node.

TECHNICAL FIELD

The present disclosure relates generally to methods and network nodes for handling handover of a user equipment (UE). The present disclosure further relates to computer programs and carriers corresponding to the above methods and network nodes.

BACKGROUND

In wireless communication there is a constant demand on higher data rates and thereby higher throughput over wireless communication interfaces between a UE and a network node, aka base station.

Carrier aggregation (CA) is an effective technique in Long Term Evolution (LTE) and New Radio (NR) to enhance throughput from/to a UE. With CA, a UE can be served with multiple carrier components (CC) and access larger bandwidth than being served with only one carrier. To apply CA, a UE firstly establishes a radio resource control (RRC) connection with a primary serving cell aka primary cell (PCell). Then the network node handling the PCell adds and removes secondary serving cells aka secondary cells (SCell) to/from the UE with RRC reconfiguration messages, depending for example on the required throughput of the UE. In order to improve UE throughput, the added SCell should have not only a good radio link to the UE but also large amount of radio resources that it can use to serve the UE, i.e., the added SCell should not be heavily loaded. How to properly configure the SCells of a UE is essential in the application of CA. When configuring SCells, the network node also needs to take the capabilities of the UE into account.

In NR and LTE, the UE informs the network about its capabilities, i.e., the UE informs the network which features and functions it supports. The network (NW) needs to take those capabilities and its own configuration into account when deciding how to configure a UE, i.e., which features to use. The UE capabilities determine which band combinations and carrier aggregation configurations that the UE supports, the number of supported Multiple Input Multiple Output (MIMO) layers and modulation order, supported subcarrier spacings and carrier bandwidths, etc. However, there are many more capabilities, especially in the physical layer area. The large amount of UE capabilities for NR are signaled via RRC, see e.g. TS 38.331, V 16.6.0, section 6.3.3. The NW should only configure those features if the UE reports the corresponding capability parameters.

One task for a network node serving a UE is to evaluate different cells to configure for the specific UE. In the context of CA, this procedure should configure the UE with the best possible alternatives of PCell and SCells. This may be called traffic steering. One traffic steering application could aim for maximizing the throughput for the ongoing connection for a specific UE. The network node would then gather information about the surrounding cells aka neighboring cells like static configuration and dynamic parameters like load. It should also take the UE capabilities into account when deciding the best set of cells, i.e. PCell and SCells, for the UE. Other information to take into account is if target cells different than the current serving cell are in coverage or not and, if possible, the channel quality for each target cell. Once the network node has determined the best set of cells for a specific UE, the UE is requested to perform handover towards the target PCell. In connection with the UE being requested to perform handover to the target cell, the serving network node sends a handover request message to the network node handling the target cell, including the ID of the target cell. In the handover process, the network node handling the target cell then checks if it can handle the request and thereafter sends a handover request acknowledgement message back to the serving network node. Then the serving network node sends a RRC reconfiguration handover command to the UE, which connects to the target node.

SUMMARY

It is an object of the invention to address at least some of the problems and issues outlined above. Embodiments of the present invention aim to improve the current UE handover process. It is possible to achieve these objects and others by using methods, network nodes and wireless devices as defined in the attached independent claims.

According to one aspect, a method is provided that is performed by a serving network node of a wireless communication network, the serving network node serving a UE and the serving network node handling a serving cell. The method comprises determining, based on capabilities of the UE, on configuration parameters of neighboring cells and the serving cell as well as on channel quality of signals received by the UE from network nodes handling the neighboring cells as well as on channel quality of signals received by the UE from the serving network node, a primary cell and at least one secondary cell for the UE. When the determined primary cell is handled by a target network node, which is different from the serving network node, the method comprises sending a handover message towards the target network node, the handover message comprising ID of the determined primary cell. In addition, the handover message further comprises ID(s) of the determined at least one secondary cell.

According to another aspect, a method is provided that is performed by a target network node of a wireless communication network, the target network node handling a target cell. The method comprises receiving a handover message from a serving network node serving a UE, the handover message comprising an ID of a determined primary cell for the UE, the primary cell being the target cell, and ID(s) of determined at least one secondary cell for the UE. The method further comprises determining whether to set up the determined target cell as primary cell for the UE and whether to set up the determined at least one secondary cell as secondary cell for the UE.

According to another aspect, a serving network node is provided that is configured to operate in a wireless communication network for serving a UE, the serving network node being configured to handle a serving cell. The serving network node comprises a processing circuitry and a memory. Said memory contains instructions executable by said processing circuitry, whereby the serving network node is operative for determining, based on capabilities of the UE, on configuration parameters of neighboring cells and the serving cell as well as on channel quality of signals received by the UE from network nodes handling the neighboring cells as well as on channel quality of signals received by the UE from the serving network node, a primary cell and at least one secondary cell for the UE. The serving network node is further operative for, when the determined primary cell is handled by a target network node, which is different from the serving network node, sending a handover message towards the target network node, the handover message comprising an ID of the determined primary cell and IDs of the at least one secondary cell.

According to another aspect, a target network node is provided that is configured to operate in a wireless communication network, the target network node being configured to handle a target cell. The target network node comprises a processing circuitry and a memory. Said memory contains instructions executable by said processing circuitry, whereby the target network node is operative for receiving a handover message from a serving network node serving a UE, the handover message comprising an ID of a determined primary cell for the UE, the primary cell being the target cell, and IDs of determined at least one secondary cell for the UE, and determining whether to set up the determined target cell as primary cell for the UE and whether to set up the determined at least one secondary cell as secondary cell for the UE.

According to other aspects, computer programs and carriers are also provided, the details of which will be described in the claims and the detailed description.

Further possible features and benefits of this solution will become apparent from the detailed description below.

DETAILED DESCRIPTION

Briefly described, a solution is provided to improve the current handover process of a UE, especially when carrier aggregation (CA) is involved. Some embodiments aim to improve the current UE handover process by reducing the time to setup CA in connection with handover. This may be achieved by the current serving network node, apart from sending in the handover message the ID of the determined target primary cell to the target network node handling the target primary cell, also sending the ID(s) of the secondary cell(s) the current serving network node determined as the best set of cells for the UE. Then the target network can set up a secondary connection for the UE with the secondary cell(s) directly, or at least evaluate whether to set up such a secondary connection. As a result, the configuration time for setting up carrier aggregation at the target network node as well as the processing required on the target network node will decrease.

FIG.1shows an example of a wireless communication network100in which the present invention may be used. The wireless communication network130comprises a first radio access network (RAN) node aka network node130that is in, or is adapted for, wireless communication with a wireless communication device aka user equipment (UE)140. The first network node130provides radio access in a first cell135. The first network node is here called a serving network node as it serves or is adapted for serving the UE140with radio access. The first cell is for the same reason called a serving cell. The wireless communication network100further comprises a second network node150providing radio access in a second cell155and a third network node160providing radio access in a third cell165and a fourth cell175. The second, third and fourth cells155,165,175are called neighboring cells as they are geographically more or less close to the serving cell135. The UE140has capabilities to be in carrier aggregation (CA) mode. Therefore, the serving network node135evaluates best primary cell and secondary cell for the UE based on the UE capabilities, configuration parameters of the serving cell and neighboring cells and channel quality of signals received by the UE140from the network nodes150,160handling the neighboring cells155,165,175as well as on channel quality of signals received by the UE from the serving network node130.

Based on the above-mentioned evaluation, the serving network node130determines that the UE140should be best served in CA by the second cell155being primary cell and the third cell165being secondary cell. The second cell155is therefore called a target cell or primary cell in this context, and the second network node150a target network node. As a result of the determination, the serving network node130initiates handover to the second cell155(illustrated by the arrow from cell135to cell155inFIG.1) by sending a handover message to the target network node150, including the ID of the target cell155. In addition, and according to embodiments, also the ID of the third cell165, which was determined as the best secondary cell for the UE is sent in the handover message. Hereby, the time for setting up CA at the new primary cell155is decreased.

The wireless communication network100may be any kind of wireless communication network that can provide radio access to wireless devices. Example of such wireless communication networks are networks based on Global System for Mobile communication (GSM), Enhanced Data Rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA 2000), Long Term Evolution (LTE), LTE Advanced, Wireless Local Area Networks (WLAN), Worldwide Interoperability for Microwave Access (WiMAX), WiMAX Advanced, as well as fifth generation (5G) wireless communication networks based on technology such as New Radio (NR), and any possible future sixth generation (6G) wireless communication network.

The network nodes130,150,160may each be any kind of network node that can provide wireless access to the UE alone or in combination with another network node. Examples of network nodes130,150,160are a base station (BS), a radio BS, a base transceiver station, a BS controller, a network controller, a Node B (NB), an evolved Node B (eNB), a gNodeB (gNB), a Multi-cell/multicast Coordination Entity, a relay node, an access point (AP), a radio AP, a remote radio unit (RRU), a remote radio head (RRH) and a multi-standard BS (MSR BS).

The UE140may be any type of device capable of wirelessly communicating with a network node130using radio signals. For example, the UE may be a machine type UE or a UE capable of machine to machine (M2M) communication, a sensor, a tablet, a mobile terminal, a smart phone, a laptop embedded equipped (LEE), a laptop mounted equipment (LME), a USB dongle, a Customer Premises Equipment (CPE) etc.

FIG.2, in conjunction withFIG.1, describes a method performed by a serving network node130of a wireless communication network100, the serving network node130serving a UE140and the serving network node handling a serving cell135. The method comprises determining202, based on capabilities of the UE140, on configuration parameters of neighboring cells155,165,175and the serving cell135as well as on channel quality of signals received by the UE140from network nodes150,160handling the neighboring cells155,165,175as well as on channel quality of signals received by the UE from the serving network node130, a primary cell155and at least one secondary cell165for the UE140. When the determined primary cell155is handled203by a target network node150, which is different from the serving network node130, the method comprises sending204a handover message towards the target network node150, the handover message comprising ID of the determined primary cell155. In addition, the handover message further comprises ID(s) of the determined at least one secondary cell165.

The handover message may also comprise ID of the UE (140). Alternatively, the target network node150informs the serving network node130of a specific preamble to use during random access. This in included in UE configuration parameters sent back to the serving network node130before handover. The serving network node130sends this to the UE140in e.g., a RRC reconfiguration message and the UE uses the preamble towards the target network node150during random access. In this alternative it is not necessary to send the UE ID in the handover message from the serving network node130to the target network node150. The primary cell155and at least one secondary cell165for the UE140are part of the neighboring cells. The determining202of primary and secondary cells may be triggered by one or more events such as the UE coming into coverage of new cells, at connection setup or RRC resume or by a periodic timer. Examples of UE capabilities may be which carrier bandwidths that are supported, carrier aggregation configurations, number of supported MIMO layers, modulation order, which carriers that can be combined in carrier aggregation, etc. Examples of configuration parameters of neighboring cells and serving cell may be bandwidth, number of MIMO layers, Time Division Duplex (TDD) or Frequency Division Duplex (FDD), TDD pattern, Subcarrier spacing, etc. Channel quality may be determined from measurement on signals received by the UE140. Channel quality may be measured as signal strength, Signal to Noise Ratio (SNR), Signal to Interference and Noise Ratio (SINR), etc. The UE140measures the channel quality of the signals the UE receives from the network nodes150,160handling the neighboring cells155,165,175as well as from the serving network node130. The serving network node130then receives from the UE140, information on the channel quality of the signals the UE140has received from the network nodes150,160handling the neighboring cells155,165,175as well as information on the channel quality of the signals the UE140has received from the serving network node130. The serving network node130uses that information on channel quality to determine the primary cell and the at least one secondary cell for the UE140.

By the serving network node130sending to the target network node150, except for the ID of the primary cell also the IDs of the one or more secondary cells it has determined, configuration of SCells in coverage can be performed faster at the target network node150in connection with handover compared to today's method where the IDs of the one or more secondary cells are not sent. Also, the computational costs for the target network node150decreases as the determinations from the serving network node/source node is re-used. Another advantage is that no new measurements may be needed in the target network node150for finding secondary cells in coverage.

According to an embodiment, the determining (202) further comprises determining a secondary cell group (SCG) comprising a Primary Secondary Cell (PSCell) of the SCG as well as at least one Secondary Cell (SCell) of the SCG, and wherein the handover message further comprises ID of the PSCell and ID(s) of the at least one SCell of the SCG. By sending the IDs of the SCG, the target network node can quicker set up an SCG if needed.

According to another embodiment, the handover message further comprises MIMO configuration parameters such as number of MIMO layers, or Layer 1 configuration parameters for the UE (140).

According to another embodiment, the ID of the determined202primary cell155and the ID(s) of the at least one secondary cell165are Cell Global identities, CGIs. CGI is a unique Cell ID of the wireless communication network. PCI is not unique and since there is a limited number to choose from, in NR there are just 1008 different PCIs, PCI can only be locally unique. Also, the same PCI can be used by cells covering the same area but on different frequencies, so only sending PCI will in most cases not be enough to identify target cell.

According to another embodiment, the handover message further comprises information on channel quality of signals received by the UE140from the target network node150handling the primary cell155and on channel quality of signals received by the UE140from the network node160handling the at least one secondary cell165. The UE140measures the channel qualities of the received signals and sends information on the channel qualities to the serving network node130that in its turn sends information on the measured channel qualities of the determined primary cell155and the at least one secondary cell165to the target network node150. By receiving not only the IDs of the primary and the secondary cells determined by the serving network node130but also the channel qualities of those cells, the target network node150has even more information for determining whether to accept the received IDs of secondary cells as the secondary cells for CA for the UE140in connection with handover.

According to yet another embodiment, the handover message further comprises information on which frequencies that were considered for the channel quality when the primary cell and the at least one secondary cell was determined202. By, in the handover message, also sending information on which frequencies the UE measured channel quality, the target network node150would know if there are any frequencies that itself or any of its neighboring nodes handle that have not been taken into consideration by the serving network node130and can hereby decide whether to do an own search for channel quality on those frequencies.

According to yet another embodiment, the handover message further comprises information on channel quality of signals received by the UE140from network nodes handling other of the neighboring cells that were not being determined202as the primary cell or any of the one or more secondary cells, as well as IDs of those cells. By also sending information in the handover message of the channel qualities of other cells that were measured but not selected as primary or secondary cell, the target network node150can also take such information into consideration when determining whether to set up the target cell155as primary cell for the UE140and the at least one secondary cell165as secondary cell for the UE140.

FIG.3, in conjunction withFIG.1, describes a method performed by a target network node150of a wireless communication network100, the target network node150handling a target cell155. The method comprises receiving302a handover message from a serving network node130serving a UE140, the handover message comprising an ID of a determined primary cell for the UE, the primary cell being the target cell155, and ID(s) of determined at least one secondary cell165for the UE. The method further comprises determining304whether to set up the determined target cell155as primary cell for the UE and whether to set up the determined at least one secondary cell165as secondary cell for the UE.

The primary cell and the at least one secondary cells have been determined by the serving network node130based on capabilities of the UE140, on configuration parameters of neighboring cells155,165,175and the serving cell135as well as on channel quality of signals received by the UE140from network nodes150,160handling the neighboring cells155,165,175as well as on channel quality of signals received by the UE from the serving network node130. The target cell155is among the neighboring cells155,165,175.

By the target network node150determining whether to set up the target cell155as primary cell for the UE and whether to set up the at least one secondary cell165as secondary cell for the UE gives the target network node control of the handling of its own resources. It can be assumed that mostly the target network node will accept the at least one secondary nodes sent by the serving network node but it may be situations when it may be not accepted. One such reason could be that the target network node150considers that the UE140does not need the extra SCell capacity when having the target cell as primary cell. It could also be that target network node150has information about that the secondary cell is not accessible or overloaded.

According to an embodiment, the received302handover message further comprises an ID of a determined PSCell of an SCG for the UE and IDs of a determined at least one SCell of the SCG.

According to another embodiment, the received302handover message further comprises MIMO configuration parameters such as number of MIMO layers, or Layer 1 configuration parameters for the UE140.

According to another embodiment, the received302handover message further comprises information on channel quality of signals received by the UE140from the target network node150handling the determined primary cell155and on channel quality of signals received by the UE from the network node160handling the determined at least one secondary cell165.

According to yet another embodiment, the received302handover message further comprises information on which frequencies the serving network node130considered when it determined the primary cell and the at least one secondary cell for the UE.

According to yet another embodiment, the received302handover message further comprises information on channel quality and ID of other cells evaluated by the serving network node but not being determined by the serving network node130as the primary cell or any of the one or more secondary cells.

FIG.4shows an example of a wireless communication network400comprising a serving network node410providing radio access in a serving cell415, a target network node420providing radio access in a target cell425, which is a neighbor cell to the serving cell415, and another network node430providing radio access in another neighbor cell435. Further, network node410is called serving network node as it is serving a UE440. The UE440has capabilities to aggregate the target cell425and the another neighbor cell435, which the UE440has indicated to the serving network node410via the UE capabilities. As the serving network node410calculates the optimal CA cell set for the UE based on the UE140capabilities, configuration parameters of cells and channel quality of the cells, the serving network node410concludes that the UE440will experience better performance if it performs a handover (HO) to target cell425and then aggregates the another neighbor cell435as a SCell. The serving network node410will therefore initiate a HO procedure for the UE440towards the target network node420that handles the target cell425. The arrow inFIG.4symbolizes handover of serving cell for the UE from cell410to the target cell425. The HO procedure is initiated by the serving network node410sending a HO message to the target network node420. According to embodiments of the invention, the serving network node410would send traffic steering information including the calculated optimal cell set in the HO message, that is not only the ID of the target cell425but also the ID of the another neighbor cell435as a SCell. That would eliminate the need for the target network node to perform calculation of new cell set after the HO is finalized. The sent traffic steering information may also include MIMO configuration for the UE.

FIG.5shows how the handling of handover requests is described for NR today as in 3GPP TS 38.423 v16.7, FIG. 8.2.1.2-1. Here the serving network node is called source node510. NG-RAN stands for Next Generation RAN. The source node510sends a Handover Request to the target node520, and the target node520responds by a Handover Request Acknowledge. The Handover Request contains a large number of handover parameters. One way of conveying the traffic steering information mentioned above, that is the calculated optimal cell set and possibly the MIMO configuration in the HO message could be to add extra information elements (IE) into the Handover Request. The extra IE could be called Traffic Steering Data and contain a Suggested SCell list, which contains SCell nCGI, where “n” in nCGI stands for NR. Also, MIMO configurations like number of MIMO layers, and/or Layer 1 configuration may be indicated as an IE. The information sent in the Handover Request message can then be used by the target node520directly when configuring the UE with for example SCells. This means that the target node520does not need to spend time on calculating the best cell set, which will both save computational effort on the target node and speed up the SCell selection.

Another way of sending the information from source node510to target node520could be to use a NG HO procedure described in 3GPP TS 38.413 v16.7, which in a normal case would be a combination of two procedures Handover preparation, which is shown inFIG.6aand Handover Resource allocation which is shown inFIG.6b. In this type of NG HO procedure, the source node510and the target node520communicate via an Access and Mobility Management Function (AMF)530of the wireless communication network. The source node510sends the HO message as a Handover Required to the AMF530. The AMF530sends the HO message further to the target node520as a Handover Request. The target node520then responds to the AMF530with a Handover Request Acknowledge, and the AMF530sends a Handover Command to the source node510in response to the received Handover Request Acknowledge. In both the Handover Required and the Handover Request message, the traffic steering information, i.e. the calculated SCells and possible other information such as MIMO configuration, can be sent in a IE Source to Target Transparent Container. The traffic steering information is not needed in the AMF530and is therefore suitable to send in a transparent container. In NR, the IE Source to Target Transparent Container carries a IE Source NG-RAN Node to Target NG-RAN Node Transparent Container. The extra IE could be called Traffic Steering Data and contain a Suggested SCell list, which contains SCell nCGI, where “n” in nCGI stands for NR.

FIG.7, in conjunction withFIG.1, describes a serving network node130configured to operate in a wireless communication network100for serving a UE140, the serving network node being configured to handle a serving cell135. The serving network node130comprises a processing circuitry603and a memory604. Said memory contains instructions executable by said processing circuitry, whereby the serving network node130is operative for determining, based on capabilities of the UE140, on configuration parameters of neighboring cells155,165,175and the serving cell135as well as on channel quality of signals received by the UE140from network nodes150,160handling the neighboring cells155,165,175as well as on channel quality of signals received by the UE from the serving network node130, a primary cell155and at least one secondary cell165for the UE140. The serving network node130is further operative for, when the determined primary cell155is handled by a target network node150, which is different from the serving network node130, sending a handover message towards the target network node150, the handover message comprising an ID of the determined primary cell155and IDs of the at least one secondary cell165.

The serving network node130may be realized as a group of network nodes, wherein functionality of the serving network node is spread out over the group of network nodes. The group of network nodes may be different physical, or virtual, nodes of the network. This alternative realization may be called a cloud-solution. Also, the target network node150may have this alternative realization.

According to an embodiment, the serving network node130is operative for the determining of primary cell155and at least one secondary cell165for the UE140by determining a secondary cell group, SCG, comprising a Primary Secondary Cell, PSCell, of the SCG as well as at least one Secondary Cell, SCell, of the SCG, and wherein the handover message further comprises an ID of the PSCell and IDs of the at least one SCell of the SCG.

According to another embodiment, the handover message further comprises MIMO configuration parameters such as number of MIMO layers, or Layer 1 configuration parameters for the UE140.

According to another embodiment, the handover message further comprises information on channel quality of signals received by the UE140from the target network node150handling the primary cell155and on channel quality of signals received by the UE from the network node160handling the at least one secondary cell165.

According to another embodiment, the handover message further comprises information on which frequencies that were considered for the channel quality when the primary cell and the at least one secondary cell was determined.

According to yet another embodiment, the handover message further comprises information on channel quality of signals received by the UE140from network nodes handling other of the neighboring cells that were not being determined as the primary cell or any of the one or more secondary cells, as well as IDs of those cells.

According to other embodiments, the serving network node130may further comprise a communication unit602, which may be considered to comprise conventional means for wireless communication with the wireless device140, such as a transceiver for wireless transmission and reception of signals in the communication network. The communication unit602may also comprise conventional means for communication with other network nodes of the wireless communication network100, such as the target network node150. The instructions executable by said processing circuitry603may be arranged as a computer program605stored e.g. in said memory604. The processing circuitry603and the memory604may be arranged in a sub-arrangement601. The sub-arrangement601may be a micro-processor and adequate software and storage therefore, a Programmable Logic Device, PLD, or other electronic component(s)/processing circuit(s) configured to perform the methods mentioned above. The processing circuitry603may comprise one or more programmable processor, application-specific integrated circuits, field programmable gate arrays or combinations of these adapted to execute instructions.

The computer program605may be arranged such that when its instructions are run in the processing circuitry, they cause the serving network node130to perform the steps described in any of the described embodiments of the serving network node130and its method. The computer program605may be carried by a computer program product connectable to the processing circuitry603. The computer program product may be the memory604, or at least arranged in the memory. The memory604may be realized as for example a RAM (Random-access memory), ROM (Read-Only Memory) or an EEPROM (Electrical Erasable Programmable ROM). In some embodiments, a carrier may contain the computer program605. The carrier may be one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or computer readable storage medium. The computer-readable storage medium may be e.g. a CD, DVD or flash memory, from which the program could be downloaded into the memory604. Alternatively, the computer program may be stored on a server or any other entity to which the serving network node130has access via the communication unit602. The computer program605may then be downloaded from the server into the memory604.

FIG.8, in conjunction withFIG.1, describes a target network node150configured to operate in a wireless communication network100, the target network node being configured to handle a target cell155. The target network node150comprises a processing circuitry703and a memory704. Said memory contains instructions executable by said processing circuitry, whereby the target network node150is operative for receiving a handover message from a serving network node130serving a UE140, the handover message comprising an ID of a determined primary cell for the UE, the primary cell being the target cell155, and IDs of determined at least one secondary cell165for the UE, and determining whether to set up the determined target cell155as primary cell for the UE and whether to set up the determined at least one secondary cell165as secondary cell for the UE.

According to an embodiment, the handover message further comprises ID of a determined PSCell of an SCG for the UE and IDs of a determined at least one SCell of the SCG.

According to another embodiment, the handover message further comprises MIMO configuration parameters such as number of MIMO layers, or Layer 1 configuration parameters for the UE140.

According to another embodiment, the handover message further comprises information on channel quality of signals received by the UE140from the target network node150handling the determined primary cell155and on channel quality of signals received by the UE from the network node160handling the determined at least one secondary cell165.

According to another embodiment, the handover message further comprises information on which frequencies the serving network node130considered when it determined the primary cell and the at least one secondary cell for the UE.

According to yet another embodiment, the handover message further comprises information on channel quality and ID of other cells evaluated by the serving network node but not being determined by the serving network node130as the primary cell or any of the one or more secondary cells.

According to other embodiments, the target network node150may further comprise a communication unit702, which may be considered to comprise conventional means for wireless communication with the wireless device140, such as a transceiver for wireless transmission and reception of signals in the communication network. The communication unit702may also comprise conventional means for communication with other network nodes of the wireless communication network100, such as the serving network node130. The instructions executable by said processing circuitry703may be arranged as a computer program705stored e.g. in said memory704. The processing circuitry703and the memory704may be arranged in a sub-arrangement701. The sub-arrangement701may be a micro-processor and adequate software and storage therefore, a Programmable Logic Device, PLD, or other electronic component(s)/processing circuit(s) configured to perform the methods mentioned above. The processing circuitry703may comprise one or more programmable processor, application-specific integrated circuits, field programmable gate arrays or combinations of these adapted to execute instructions.

The computer program705may be arranged such that when its instructions are run in the processing circuitry, they cause the target network node150to perform the steps described in any of the described embodiments of the target network node150and its method. The computer program705may be carried by a computer program product connectable to the processing circuitry703. The computer program product may be the memory704, or at least arranged in the memory. The memory704may be realized as for example a RAM (Random-access memory), ROM (Read-Only Memory) or an EEPROM (Electrical Erasable Programmable ROM). In some embodiments, a carrier may contain the computer program705. The carrier may be one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or computer readable storage medium. The computer-readable storage medium may be e.g. a CD, DVD or flash memory, from which the program could be downloaded into the memory704. Alternatively, the computer program may be stored on a server or any other entity to which the target network node150has access via the communication unit702. The computer program705may then be downloaded from the server into the memory704.