WO2017204741A1

WO2017204741A1 - Method and arrangements for managing cell identities in a wireless communication network

Info

Publication number: WO2017204741A1
Application number: PCT/SE2017/050562
Authority: WO
Inventors: Tobias AHLSTRÖM; Sofia NYBERG
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2016-05-27
Filing date: 2017-05-24
Publication date: 2017-11-30

Abstract

A method performed by one or more nodes (110a; 110b; 110c; 130; 201; 202), for managing cell identities in a wireless communication network (100) when cells (115a, 115c, 115e) of the wireless communication network (100) are having identical cell 5 identities that cause a conflict. It is obtained (601-602; 701; 902; 1001) information identifying cells (115a, 115c, 115e) that are having a same, first cell identity. A cell (115a) of said cells (115a, 115c, 115e) is selected (603; 702-706; 903; 1002) to change cell identity to another, second cell identity. The selection is based on one or more of: which among said cells (115a, 115c, 115e) that is associated with a largest number of available 10 cell identities, and which among said cells (115a, 115c, 115e) that is having a largest number of neighbouring cells to its neighbour cells, which neighbouring cells are having the same cell identity.

Description

METHOD AND ARRANGEMENTS FOR MANAGING CELL IDENTITIES IN A WIRELESS

COMMUNICATION NETWORK

TECHNICAL FIELD

Embodiments herein relate to a method and arrangements in or for communication with a wireless communication network, e.g. telecommunication network, for managing cell identities in the wireless communication network when cells of the wireless communication network are having identical cell identities that cause a conflict. BACKGROUND

Communication devices such as wireless communication devices, that simply may be named wireless devices, may also be known as e.g. User Equipments (UEs), mobile terminals, wireless terminals and/or Mobile Stations (MS). A wireless device is enabled to communicate wirelessly in a wireless communication network that typically is a cellular communications network, which may also be referred to as a wireless communication system, or radio communication system, sometimes also referred to as a cellular radio system, cellular network or cellular communication system. A wireless communication network may sometimes simply be referred to as a network and abbreviated NW. The communication may be performed e.g. between two wireless devices, between a wireless device and a regular telephone and/or between a wireless device and a server via a Radio Access Network (RAN) and possibly one or more Core Networks (CN), comprised within the wireless communication network. The wireless device may further be referred to as a mobile telephone, cellular telephone, laptop, Personal Digital Assistant (PDA), tablet computer, just to mention some further examples. Wireless devices may be so called Machine to Machine (M2M) devices or Machine Type Communication (MTC) devices, i.e. a device that is not necessarily associated with a conventional user, such as a human, directly using the device. MTC devices may be as defined by 3GPP:

The wireless device may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data, via the RAN, with another entity, such as another wireless device or a server.

The cellular communication network covers a geographical area which is divided into cell areas, wherein each cell area is served by at least one base station, or Base Station (BS), e.g. a Radio Base Station (RBS), which sometimes may be referred to as e.g. "eNB", "eNodeB", "NodeB", "B node", or BTS (Base Transceiver Station), depending on the technology and terminology used. The base stations may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. A cell is typically identified by one or more cell identities. The base station at a base station site provides radio coverage for one or more cells. A cell is thus associated with a geographical area where radio coverage for that cell is provided by the base station at the base station site. Cells may overlap so that several cells cover the same geographical area. By the base station providing or serving a cell is meant that the base station provides radio coverage such that one or more wireless devices located in the geographical area where the radio coverage is provided may be served by the base station in said cell. When a wireless device is said to be served in or by a cell this implies that the wireless device is served by the base station providing radio coverage for the cell. One base station may serve one or several cells. Further, each base station may support one or several communication technologies. The base stations communicate over the air interface operating on radio frequencies with the wireless device within range of the base stations.

In some RANs, several base stations may be connected, e.g. by landlines or microwave, to a radio network controller, e.g. a Radio Network Controller (RNC) in Universal Mobile Telecommunication System (UMTS), and/or to each other. The radio network controller, also sometimes termed a Base Station Controller (BSC) e.g. in GSM, may supervise and coordinate various activities of the plural base stations connected thereto. GSM is an abbreviation for Global System for Mobile Communication (originally: Groupe Special Mobile).

In 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), base stations, which may be referred to as eNodeBs or eNBs, may be directly connected to other base stations and may be directly connected to one or more core networks.

UMTS is a third generation mobile communication system, which may be referred to as 3rd generation or 3G, and which evolved from the GSM, and provides improved mobile communication services based on Wdeband Code Division Multiple Access (WCDMA) access technology. UMTS Terrestrial Radio Access Network (UTRAN) is essentially a radio access network using wideband code division multiple access for wireless devices.

General Packet Radio Service (GPRS) is a packet oriented mobile data service on the 2G cellular communication system's global system for mobile communications (GSM).

Enhanced Data rates for GSM Evolution (EDGE) also known as Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT-SC), or Enhanced Data rates for Global Evolution is a digital mobile phone technology that allows improved data transmission rates as a backward-compatible extension of GSM.

High Speed Packet Access (HSPA) is an amalgamation of two mobile telephony protocols, High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA), defined by 3GPP, that extends and improves the performance of existing 3rd generation mobile telecommunication networks utilizing the WCDMA. Such networks may be named WCDMA/HSPA.

The 3GPP has undertaken to evolve further the UTRAN and GSM based radio access network technologies, for example into evolved UTRAN (E-UTRAN) used in LTE.

The expression downlink, which may be abbreviated DL, is used for the

transmission path from the base station to the wireless device. The expression uplink, which may be abbreviated UL, is used for the transmission path in the opposite direction i.e. from the wireless device to the base station. Figure 1 schematically shows an LTE architecture with logical interfaces between eNBs, so called X2 interfaces, and between eNBs and Mobility Management Entities and/or Serving Gateways (MME/S-GW), so called S1 interfaces. LTE is part of the Evolved Packet System (EPS), also constituting the Evolved Packet Core (EPC). The architecture of the EPS system is shown in Figure 1 , including radio access nodes, here eNBs, and EPS nodes, here MME/S-GW. The interface between eNBs is referred to as X2, and the interface between eNB and MME/S-GW is denoted S1. The signalling transport over X2 and S1 are implemented via a Stream Control Transmission Protocol (SCTP), see e.g. 3GPP TS 36.412 v.13.0.0, 3GPP TS 36.422, v.13.0.0, RFC 4960 (September 2007).

The Network Elements (NE), here the eNBs, are managed by a Domain Manager (DM), also referred to as the Operation and Support System (OSS). A DM may further be managed by a network manager (NM). Two NEs are interfaced by X2, whereas the interface between two DMs is referred to as ltf-P2P. The management system may configure the network elements, as well as receive observations associated with features in the network elements. For example, the DM observes and configures NEs, while NM observes and configures DMs, as well as NEs via DM. Management information describing the current configuration of an eNB may also be transferred over the X2 ingterface to neighbour eNBs.

Figure 2 schematically shows a management system architecture that may be assumed. In an LTE network there are a couple of different identities for each cell. Two examples of cell IDs are the Eutran Cell Global Identity (ECGI) and Physical Cell Identity (PCI). The ECGI is a unique ID of a cell while the PCIs are reused in a network and therefore many cells can have the same ID. The PCI is for example used during handovers (HO) between cells, where the UE identifies the target cell by measuring the PCI.

In LTE there are 504 different PCIs, which mean that a network needs to be carefully planned since it is unfavourable that two neighbour cells have the same PCI. It is also unfavourable that one cell has two neighbours with the same PCI. These two situations are often described as a PCI conflict, i.e. a cell identity conflict.

When two neighbour cells has the same PCI a UE moving from one of the cells towards the other will not initiate a HO. Instead it will lead to a lost connection (drop) between the serving cell and the UE. Figure 3 schematically illustrates a situation with a PCI conflict between two neighbour cells. This kind of conflict may be referred to as "collision".

In a situation when one cell has two neighbours with the same PCI it cannot be distinguished which cell the UE reports when for example initiating a HO. In this case the UE is about to be handed over to a neighbour cell. The UE reports that a cell with PCI A is a suitable target. Since the source cell has two neighbour cells with PCI A it does not know which one that is the target. If the HO is done towards the left cell with PCI A the connection to the UE will be lost. Figure 4 schematically illustrates a situation with a PCI conflict between two cells that are both neighbours to a third cell. This kind of conflict may be named "confusion".

In both situations, i.e. conflict cases, above there is a temporary loss of connection which can later be re-established, but that requires extra signalling and results in degraded throughput.

One existing solution for handling PCI conflict is to thoroughly plan the PCIs in the network and do central re-planning when a new case of PCI conflict is detected, the central re-planning e.g. placed in an DM or NM. This requires signalling from the nodes involved in the conflict or from the node detecting the conflict. It also needs signalling ordering one or more of the nodes to change its PCI. In addition to that, the deciding node needs to gather information about the conflicting nodes and the network as such, in order to assign new PCI values. This problem has been seen as so called Non-deterministic Polynomial-time (NP) hard and is not easily done, the other hand the problem could be solved distributed, where not the entire network is taken into considerations, hence reducing the NP hard problem to a problem that can be solved faster.

SUMMARY

An object is to provide one or more improvements with regard to cell identities in a wireless communication network, such as preventing or reducing problems associated with that multiple cells may have the same cell identity.

According to a first aspect of embodiments herein, the object is achieved by a method, performed by one or more nodes, for managing cell identities in a wireless communication network when cells of the wireless communication network are having identical cell identities that cause a conflict. The one or more nodes obtain information identifying cells of the wireless communication network that are having a same, first cell identity. The one or more nodes select a cell of said cells to change cell identity to another, second cell identity. The selection being based on one or more of the following: which among said cells that is associated with a largest number of available cell identities, and

which among said cells that is having a largest number of neighbouring cells to its neighbour cells, which neighbouring cells are having the same cell identity.

According to a second aspect of embodiments herein, the object is achieved by a computer program comprising instructions that when executed by a node causes the node to perform the method according to the first aspect. According to a third aspect of embodiments herein, the object is achieved by a computer readable medium comprising the computer program according to the second aspect.

According to a fourth aspect of embodiments herein, the object is achieved by a node for managing cell identities in a wireless communication network when cells of the wireless communication network are having identical cell identities that cause a conflict. The node is configured to obtain information identifying cells of the wireless

communication network that are having a same, first cell identity. The node is further configured to select a cell of said cells to change cell identity to another, second cell identity. The selection being based on one or more of the following: which among said cells that is associated with a largest number of available cell identities, and

In some embodiments, the one or more nodes and the node is a radio network node, such as a eNB when the wireless communication network is a Long Term Evolution (LTE) network. The cell identities are for example Physical Cell Identities (PCIs).

Thanks to embodiments herein, the number of changes and operations typically needed to solve cell identity conflicts, i.e. problems relating to cells having the same cell identity, such as solving a PCI conflict, can be lowered or even be minimized. This reduces signalling, and disturbances etc. of traffic in the wireless communication network can be reduced, thus improving e.g. uptime and user experience, and enables provision of more robust services.

BRIEF DESCRIPTION OF THE DRAWINGS

The various aspects of embodiments disclosed herein, including particular features and advantages thereof, will be readily understood from the following detailed description and the accompanying drawings, in which Figures 1-12 are shown.

Figure 1 schematically shows an LTE architecture with logical interfaces.

Figure 2 schematically shows a management system architecture.

Figure 3 schematically illustrates a situation with a PCI conflict between two neighbour cells.

Figure 4 schematically illustrates a situation with a PCI conflict between two cells that are both neighbours to a third cell.

Figure 5 is a block diagram schematically depicting an example of a wireless communication network in which embodiments may be implemented.

Figure 6 is an example of schematic signalling for resolving a Physical Cell Identity (PCI) conflict in a centralized manner.

Figure 7 is a schematic example of high level signalling for resolving a Physical Cell

Identity (PCI) conflict in a de-centralized manner.

Figure 8 schematically illustrates a scenario with cell conflicts of confusion type.

Figure 9 is a combined signalling diagram and flowchart for describing some embodiments herein. Figure 10 is a flowchart schematically illustrating embodiments of a method according to embodiments herein.

Figure 1 1 is a functional block diagram schematically illustrating embodiments of a node and how it can be configured to carry out the method.

Figures 12a-c are schematic drawings illustrating embodiments relating to computer programs and computer readable media to cause the node to perform the method.

DETAILED DESCRIPTION

Throughout the following description similar reference numerals may be used to denote similar elements, units, modules, circuits, nodes, parts, items or features, when applicable. In the Figures, features that appear only in some embodiments are typically indicated by dashed lines.

In the following, embodiments herein are illustrated by exemplary embodiments. It should be noted that these embodiments are not mutually exclusive. Components from one embodiment may be tacitly assumed to be present in another embodiment and it will be obvious to a person skilled in the art how those components may be used in the other exemplary embodiments.

Figure 5 is a schematic block diagram schematically depicting an example of a wireless communication network 100 in which embodiments herein may be

implemented. The wireless communication network 100 is typically a telecommunication network or system, such as a cellular communication network that may be a LTE or a LTE based communication network. It may comprise a RAN 101 part and a Core Network (CN) 102 part.

A first network node 110a, typically a radio network node such as a base station or eNB, is shown comprised in the wireless communication network 100 and may thus be located in the RAN 101. The first network node 1 10a may provide a first cell 115a.

Further, also shown in the wireless communication network 100 a second network node 110b, typically a radio network node such as a base station or eNB, and a third network node 110c, also typically a radio network node such as a base station or eNB. The second network node 110b may e.g. provide a second cell 115b and a third cell 115c. The third network node 1 10c may e.g. provide a fourth cell 115d and a fifth cell 115e.

The wireless communication network 100, e.g. one or more of the network nodes 1 10a-c in one or more of said cells 1 15a-e, may serve and/or control and/or manage one or more communication devices, e.g. UEs or MTC devices, such as a communication device 120 that is shown in the first cell 115a in the figure. Such device may be named e.g. a wireless communication device or simply a wireless device. The communication device 120 is thus supported by and/or operative in the wireless communication network 100.

Further, the wireless communication network 100 may comprise a common node

130, i.e. a node that is common or central and communicatively connected to multiple other nodes, e.g. the network nodes 110a-c, may be for managing and/or controlling these nodes. The common node is typically comprised in the CN 101. This node may thus be core network node and/or an internal management node.

The wireless communication network, e.g. the CN 102, may further be

communicatively connected to, and e.g. provide access for said communication devices, to an external network 200, e.g. the Internet. The communication device 120 may thus communicate, via the RAN 101 and the CN 102, with the external network 200.

Moreover, there may be one or more external nodes, e.g. an external node 201 , for communication with the wireless communication network 100 and node(s) thereof. The external node 201 may e.g. be an external management node. Said one or more nodes may be comprised in the external network 200 or may be separate from this.

Furthermore, the one or more external nodes may correspond to or be comprised in a so called computer cloud, or simply cloud, such as a cloud 202 as shown in the figure, for providing certain service(s) to outside the cloud via some communication interface. The exact configuration of nodes etc. comprised in the cloud in order to provide said service(s) may not be known outside the cloud and it may not be relevant. The cloud 202, or typically rather one or more nodes thereof, may be communicatively connected to the wireless communication network 100, or certain nodes thereof, and may be providing one or more services that e.g. may provide, or facilitate, certain functions or functionality of the wireless communication network. The cloud 202 may be comprised in the external network 200 or may be separate from this.

Said internal management node and external management node may e.g. comprise or correspond to a so called Domain Manager (DM) or Network Manager (NM), at least when the wireless communication network 100 is a LTE or LTE based network.

It can further be noted that the wireless communication network 100 may support communication devices of two or more, different types and said one or more

communication devices may be of these types. The types may differ in how they operate and are operated, and/or communicate, in the wireless communication network 100. The types may share infrastructure and resources in the wireless communication network 100 but some resources, e.g. certain channels and/or certain signalling, are typically specific and/or separate and/or configured differently for each type. A certain device, e.g. the communication device 120, may be of one or more types, i.e. operable and/or supporting communication as defined for these types in the wireless communication network 100. The communication device 120 may e.g. be of a first and/or second type of said one or more types. If e.g. only being of the first type or the second type, it may not be operable and/or be affected by resources, e.g. certain channels and/or certain signalling, that are specific for the other types. It is typically so that a device, although it may support many types, only is operable according to one type at a time. A first type may e.g. be conventional, such as a legacy, type of devices, e.g. UEs, that for example may be smart phones, supporting LTE. A second type may be a MTC type, i.e. a type specific for MTC devices.

Attention is drawn to that Figure 5 is only schematic and for exemplifying purpose and that not everything shown in the figure may be required for all embodiments herein, as should be evident to the skilled person. Also, a wireless communication network or networks that in reality correspond(s) to the wireless communication network 100 and what is shown in the figure will typically comprise several further and other nodes and network nodes, such as base stations, cells, etc., as realized by the skilled person, but which are not shown herein for the sake of simplifying.

If a PCI conflict as described in the Background is going to be resolved manually the time from detecting to resolving the conflict can be unnecessary long.

Figure 6 is an example of schematic signaling that may be used to resolve such conflict as described in the Background, e.g. the wireless communication network 100. The figure schematically shows signalling for resolving a PCI conflict using a central network node that e.g. may correspond to the common node 130, the external node 201 or the cloud 202. To simplify, the central node may in the following be exemplified by but not be limited to the common node 130. The eNBs shown may correspond to the network nodes 1 10a-c, respectively.

In the example of Figure 6, in action 601 , a node eNB2, e.g. corresponding to the first network node 1 10a, detects that it has a PCI conflict situation with two other nodes, such as nodes eNB1 and eNB3, e.g. corresponding to second and third network nodes 1 10b-c, respectively. The node eNB1 sends, in action 602, a signal to a central network node, e.g. corresponding to the common node 130, responsible for evaluating the conflict and/or resolving the conflict in action 603. Note that this central node, e.g. the common node 130, might need to resolve a lot of conflicts occurring in the wireless communication network 100. When the situation has been evaluated, automatically, e.g. by the central node in action 603, or manually, one of the nodes should be ordered to change PCI for a conflicting cell, in the example of the figure, the node eNB3, e.g. the second network node 1 10b, to which the central node, e.g. the common node 130, in action 604 sends an order for PCI change. When the PCI then is changed in action 605, the eNB3 typically needs to inform all its neighbours about the new setting, in the example exemplified by actions 606-607 where the node eNB3, e.g. the second network node 110b, after having changed PCI in action 605, sends information updates to the nodes eNB1 and eNB2, e.g. the first and third network nodes 1 10a, c. The node eNB3 may also need to inform the central network node, e.g. the common node 130, for it to be able to keep the information about the network up to date. Otherwise the central network node may not be able to make correct evaluation and conflict resolving. This is exemplified by action 608 in the figure, where the node eNB3, e.g. the second network node 110b, after having changed PCI in action 605, also sends an information update to the central network node, e.g. the common node 130.

In LTE the information update between nodes can be done by using so called X2 connections, i.e. connections using the X2 interface. The X2 connection is used for a lot of different purposes. One of them is for example to inform a neighbour node about new settings on any cell. It can also be used for informing about settings on a neighbour node's neighbour. This e.g. means that an eNB can collect and store information about neighbour cells and neighbours' neighbour cells. That information can be used both for detecting a PCI conflict and for reselecting PCI on a conflicting cell.

Figure 7 schematically illustrates an example of another method for resolving a conflict based on letting one of the involved eNBs act as master and order a PCI change, e.g. on one of the other eNBs. An eNB thus acts as master node for resolving the conflict and is typically the same eNB that detected the conflict. This represent a more decentralized way of resolving PCI conflicts than the situation in Figure 6. In Figure 7, a node eNB2, e.g. the first network node 110a, is acting as a master node that in action 701 detects the conflict.

This typically requires that information about neighbours and neighbours' neighbours is sent to an eNB responsible for resolving the conflict. Based on the gathered information the eNB can then take a decision and e.g. order one node to change its PCI. This eNB may also provide a new PCI to the node that should change PCI. If the eNB that decides the PCI change does not have sufficient information, it cannot assure that the selected new PCI doesn't result in a new conflict. Figure 7 is thus a high level signaling chart schematically exemplifying such a scenario, or in other words, Figure 7

schematically shows example signaling for resolving a PCI conflict, where the node eNB2, e.g. the first network node 1 10a, is acting as a master node that in action 701 detects the conflict. The example in Figure 7 contains two conflicting nodes, similar as in the example of Figure 6, exemplified by the nodes eNB1 and eNB3, e.g. the third and second network nodes 110c,b. The master node, here eNB2, e.g. the first network node 110a, requests neighbour information from the conflicting nodes in actions 802, 804. The neighbour information is sent from the conflicting nodes, typically in response to said requests, i.e. from both eNB1 and eNB3, in actions 803, 805. The neighbour information may contain both information about direct neighbours but also about neighbours' neigbours. When all information is gathered, the master node, in the example eNB2, can decide which cell that should change PCI and may also provide one or more suggestions on a new PCI. In the shown example, eNB1 is ordered to change PCI for the conflicting cell. When the PCI is changed, eNB1 typically needs to inform all neighbours about the change. Above, two different approaches was mentioned for resolving PCI conflicts. When updating the PCI a cell is assigned a new ID, and is typically taken out of service for some time, which may result in an unwanted impact on traffic in the node providing the cell. For example, there may be unwanted impact on traffic in eNB1 corresponding to the third network node 1 10c, if e.g. the PCI is changed for the fourth cell 115d. Hence, it is desirable that an algorithm that resolves the conflict and changes PCI makes as few changes as possible. In other words, the algorithm for selecting PCI is typically important and what input such algorithm uses.

In a case as in Figure 6 when a network node, e.g. the central node, such as the common node 130, is responsible for resolving the conflict, it has typically knowledge of the neighbour environment of the conflicting node.

In another case as in Figure 7, i.e. where a eNB may be responsible for resolving the conflict, the eNB typically only have access to the its own neighbours and and possibly their neighbours, hence the best cell for a change of PCI may not be possible to determine based on conventional information directly available to the eNB. For example, eNB1 may have more neighbours' neighbour nodes and no available PCI's, so changing PCI of eNB1 may risk to end up in new PCI conflicts. It may be better to change PCI of another eNB, e.g. eNB3, that may have more available PCI's and a PCI change may in such case also solve more than one PCI conflict at the same time. A proposed and advantageous solution is based on letting each eNB take responsibility for resolving its own PCI conflicts.

A conflict herein, i.e. of cell identifies, such as problem due to identical cell identities, may be represented, or caused, either by a collision, such as described in the Background in connection with Figure 3, or a confusion, such as described in the

Background in connection with Figure 4.

According to this solution, a cell to change PCI should be one that:

1. Has a longest list of available PCIs.

2. Causes most confusion.

More rules may apply here as well. For example:

3. Has an available PCI that is not already present, i.e. used, within its subnetwork, where the subnetwork is referring to the cells relevant for the conflict, typically the cell, its neighbour cell(s) and neighbouring cell(s) of the neighbour cell(s), i.e. neighbours' neighbours.

A selection of a cell to change PCI based on rules like above reduces the risk of later on ending up in new PCI conflicts and reduces the total number of PCI's used and thereby makes it possible to add more nodes easily without causing conflicts.

In the case of collision e.g. as in Figure 3, both cells may, based on information about the others' neighbours and neighbours of its own, perform checks according to rule 1 and 2 above and end up in a suitable cell and node to change PCI.

A PCI Change order message may be sent by an eNB to a neighbouring eNB to trigger a change of a PCI, with direction e.g. eNB1 to eNB2, for example: IE/Group Name Presence Range IE type and Semantic Critical Assigned reference s ity Criticality descripti

on

Message Type M YES reject

Global eNB ID M YES reject

>Modify cells 0..

<maxnoofNeighb

ours>

»ECGI M 1.

<maxCelline

NB>

» Old PCI O

» New PCI O

The first rule above, relating to available PCIs, may involve to determine which PCIs that can be used. This can for example be done by starting with a complete set of PCIs. Then the node may exclude all PCIs that are:

• used by the cells on the own node

• used by any neighbour cell

• used by any neighbours' neighbour cell

The remaining PCIs may then be used and may be considered available since they thus should not cause any new conflict.

Figure 8 schematically illustrates a scenario for exemplifying the second rule above, relating to what causes most confusion, i.e. conflicts of the confusion type as explained above. The cells shown in Figure 8 may e.g. correspond to the cells 115a-e. The second rule may apply if a cell has any neighbours' neighbours with same PCI, and if this is the case, the cell is involved in more than one PCI confusion. See e.g. the middle cell with PCI=X, which may correspond to the first cell 1 15a, and which is involved in 2 confusions, one regarding the cell with PCI=Y, e.g. the fourth cell 1 15d, and one with the cell with

PCI=Z, e.g. the second cell 115b. That is, if the middle cell would have another PCI than X then there would be no confusion regarding PCI=X for the cells with PCI=Y and PCI=Z. Of course, the middle cell with PCI=X should not change to PCI=Y or PCI=Z since this then would cause another conflict of collision type. However, rule 3 above would take care of that this should not happen. Inclusion of information to facilitate implementation of the above, may be included in a 3GGP message that may be based on an existing standard message, e.g. a X2 SETUP REQUEST message shown in the following, where suggested new information is indicated in italic.

IE/Group Name Pres Range IE type and Semantics Critical Assig ence reference description ity ned

Critic ality

Message Type M 9.2.13 YES reject

Global eNB ID M 9.2.22 YES reject

Served Cells 1 .. Complete list of YES reject

<maxCellineNB cells served by

> the eNB

>Served Cell Information M 9.2.8 - -

>Neighbour Information 0..

<maxnoofNeigh

bours>

»ECGI M ECGI E-UTRAN Cell

9.2.14 Global Identifier

of the neighbour

cell

»PCI M INTEGER Physical Cell

(0..503, ...) Identifier of the

neighbour cell

»EARFCN M 9.2.26 DL EARFCN for

FDD or

EARFCN for

TDD

»TAC O OCTET Tracking Area YES ignor

STRING (2) Code e

» EARFCN Extension O 9.2.65 DL EARFCN for YES reject

FDD or

EARFCN for

TDD. If this IE is

present, the

value signalled

in the EARFCN

IE is ignored.

»Neighbours

Neighbour Information

Information

»>ECGI M ECGI E-UTRAN Cell

9.2.14 Global Identifier

of the neighbour

cell

»>PCI M INTEGER Physical Cell

(0..503, ...) Identifier of the

neighbour cell

»>EARFCN M 9.2.26 DL EARFCN for

FDD or

EARFCN for

TDD

»>TAC 0 OCTET Tracking Area YES ignor

STRING (2) Code e

»>EARFCN Extension 0 9.2.65 DL EARFCN for YES reject

FDD or

EARFCN for

TDD. If this IE is

present, the

value signalled

in the EARFCN

IE is ignored.

GU Group Id List 0.. <maxfPools> List of all the GLOBA reject pools to which L the eNB belongs

>GU Group Id M 9.2.20 - -

LHN ID O 9.2.83 YES ignor e

Further, inclusion of information to facilitate implementation of the above, may further be included in a X2 SETUP RESPONSE message shown in the following, where suggested new information is indicated in italic.

Critic ality

Message Type M 9.2.13 YES reject

Global eNB ID M 9.2.22 YES reject

Served Cells 1 .. Complete list of YES reject

<maxCellineNB cells served by

> the eNB

>Served Cell Information M 9.2.8 - -

>Neighbour Information 0..

<maxnoofNeigh

bours>

»ECGI M ECGI E-UTRAN Cell

9.2.14 Global Identifier

of the neighbour

cell

»PCI M INTEGER Physical Cell

(0..503, ...) Identifier of the

neighbour cell

»EARFCN M 9.2.26 DL EARFCN for

FDD or

EARFCN for

TDD

»TAC O OCTET Tracking Area YES ignor

STRING (2) Code e

» EARFCN Extension O 9.2.65 DL EARFCN for YES reject

FDD or

EARFCN for

TDD. If this IE is

present, the

value signalled

in the EARFCN

IE is ignored.

»Neighbours

Neighbour Information

Information

»>ECGI M ECGI E-UTRAN Cell

9.2.14 Global Identifier

of the neighbour

cell

»>PCI M INTEGER Physical Cell

(0..503, ...) Identifier of the

neighbour cell

»>EARFCN M 9.2.26 DL EARFCN for

FDD or

EARFCN for

TDD

»>TAC 0 OCTET Tracking Area YES ignor

STRING (2) Code e

»>EARFCN Extension 0 9.2.65 DL EARFCN for YES reject

FDD or

EARFCN for

TDD. If this IE is

present, the

value signalled

in the EARFCN

IE is ignored.

>GU Group Id M 9.2.20 - -

LHN ID O 9.2.83 YES ignor e

Moreover, inclusion of information to facilitate implementation of the above, may further be included in a ENB CONFIGURATION UPDATE message shown in the following, where suggested new information is indicated in italic.

IE/Group Name Prese Range IE type and Semantics Critical Assig nee reference description ity ned

Critic ality

Message Type M 9.2.13 YES reject

Served Cells To Add 0.. Complete list of GLOBA reject

<maxCellineNB added cells L

> served by the

eNB

>Served Cell Information M 9.2.8 - -

>Neighbour Information 0..

<maxnoofNeigh

bours>

»ECGI M ECGI E-UTRAN Cell

9.2.14 Global Identifier

of the neighbour

cell

»PCI M INTEGER Physical Cell

(0..503, ...) Identifier of the

neighbour cell

»EARFCN M 9.2.26 DL EARFCN for

FDD or

EARFCN for

TDD

»TAC O OCTET Tracking Area YES ignor

STRING (2) Code e

» EARFCN Extension O 9.2.65 DL EARFCN for YES reject

FDD or

EARFCN for

TDD. If this IE is

present, the

value signalled

in the EARFCN

IE is ignored.

»Neighbour's

Neighbour

Information

»>ECGI M ECGI E-UTRAN Cell

9.2.14 Global Identifier

of the neighbour

cell

»>PCI M INTEGER Physical Cell

(0..503, ...) Identifier of the

neighbour cell

»>EARFCN M 9.2.26 DL EARFCN for

FDD or

EARFCN for

TDD

»>TAC 0 OCTET Tracking Area YES ignor

STRING (2) Code e

»>EARFCN Extension 0 9.2.65 DL EARFCN for YES reject

FDD or

EARFCN for

TDD. If this IE is

present, the

value signalled

in the EARFCN

IE is ignored.

Served Cells To Modify 0.. Complete list of GLOBA reject

<maxCellineNB modified cells L

> served by the

eNB

>Old ECGI M ECGI Old E-UTRAN - - 9.2.14 Cell Global

Identifier

>Served Cell Information M 9.2.8 - -

>Neighbour Information 0..

<maxnoofNeigh

bours>

»ECGI M ECGI E-UTRAN Cell

9.2.14 Global Identifier

of the neighbour

cell

»PCI M INTEGER Physical Cell

(0..503, ...) Identifier of the

neighbour cell

»EARFCN M 9.2.26 DL EARFCN for

FDD or

EARFCN for

TDD

»TAC O OCTET Tracking Area YES ignor

STRING (2) Code e

» EARFCN Extension O 9.2.65 DL EARFCN for YES reject

FDD or

EARFCN for

TDD. If this IE is

present, the

value signalled

in the EARFCN

IE is ignored.

»Neighbours

Neighbour

Information

»>ECGI M ECGI E-UTRAN Cell

9.2.14 Global Identifier

of the neighbour

cell

»>PCI M INTEGER Physical Cell

(0..503, ...) Identifier of the

neighbour cell

»>EARFCN M 9.2.26 DL EARFCN for

FDD or

EARFCN for

TDD

»>TAC 0 OCTET Tracking Area YES ignor

STRING (2) Code e

»>EARFCN Extension 0 9.2.65 DL EARFCN for YES reject

FDD or

EARFCN for

TDD. If this IE is

present, the

value signalled

in the EARFCN

IE is ignored.

deactivation Indication O ENUMERAT Indicates that YES ignor

ED(deactivat the concerned e ed, cell is switched

...) off for energy

saving reasons

Served Cells To Delete 0.. Complete list of GLOBA reject

<maxCellineNB deleted cells L

> served by the

eNB

>Old ECGI M ECGI Old E-UTRAN

9.2.14 Cell Global

Identifier of the cell to be

deleted

GU Group Id To Add List 0.. <maxPools> GLOBA reject

L

>GU Group Id M 9.2.20 - -

GU Group Id To Delete 0.. <maxPools> GLOBA reject List L

>GU Group Id M 9.2.20 - -

Coverage Modification List 0.. List of cells with GLOBA reject

<maxCellineNB modified L

> coverage

>ECGI M ECGI E-UTRAN Cell

9.2.14 Global Identifier

of the cell to be

modified

>Cell Coverage State M INTEGER Value Ό'

(0..15, ...) indicates that

the cell is

inactive. Other

values Indicates

that the cell is

active and also

indicates the

coverage

configuration of

the concerned

cell

>Cell Deployment Status O ENUMERAT Indicates the

Indicator ED(pre- Cell Coverage

change- State is planned

notification,.. to be used at the

^■) next

reconfiguration

>Cell Replacing Info C- ifCell

Deplo

yment

Statu

slndic

atorPr

esent

»Replacing Cells 0..

<maxCellineNB

>

»>ECGI ECGI E-UTRAN Cell

9.2.14 Global Identifier

of a cell that

may replace all

or part of the

coverage of the

cell to be

modified

Additionally, or alternatively, inclusion of information to facilitate implementation of the above, may be implemented by new signalling requesting the information, e.g. a Neighbour Information Request message. This message may be sent by an eNB to a neighbouring eNB to request a transfer information of neighbour cells. Direction may be eNB1 to eNB2. This message may e.g. be implemented as in the following:

A response message to this may be a Neighbour Information Response message. This message is sent by an eNB to a neighbouring eNB to transfer information of neighbour cells. Direction may be eNB1 to eNB2. This message may e.g. be implemented as in the following:

In view of the above, a solution may thus be that an eNB discovers there is a PCI conflict, e.g. eNB2, such as the first network node 110a, in Figure 7 and action 701 , i.e. this eNB is in other words a detecting node. This eNB may either have two relations to two different cells with the same PCI or a neighbour with the same PCI, and should decide what cell that should change PCI based on certain information. The decision may e.g. be made in action 706. The information should thus not only be about neighbour cells but also their neighbour cells.

This information may be provided to the eNB, i.e. the detecting node, in two ways:

1. Be given once a relation is added and then updated,

and/or

2. By request when needed.

Hence for such scenario as illustrated in Figure 7, eNB2 will get information about both eNBI 's and eNB3's neighbours and their neighbours' neighbours, in order to be able to: know if one of the cells is involved in more than one PCI collision, to know what cell of the two nodes that is possible or suitable for PCI change, and to prevent new potential PCI collisions.

Thanks to the solutions discussed above, a number of PCI changes that has to be done when solving PCI conflicts can be lowered or even be minimized, and hence impact on the traffic is reduced.

Figure 9 depicts a combined signalling diagram and flowchart, which will be used to discuss embodiments herein relating to actions and a method. The method may be performed by a wireless communication network, e.g. the wireless communication network 100, such as a LTE or LTE based network, and/or one or more nodes or arrangements comprised in or for communication with the wireless communication network. The method relates to managing identical cell identities in a wireless

communication network, e.g. the wireless communication network 100, when this is a problem, such as when it causes a conflict as discussed herein, or in other words when multiple cells of the wireless communication network are having cell identities that are the same and this is a problem that should be solved. Said node(s) comprised in the wireless communication network may correspond to any one of the network nodes 1 10a-c, e.g. a radio network node or base station such a eNB in LTE, or the common node 130, e.g. a core network node and/or management node, such as a Domain Manager (DM) or Network Manager (NM) in LTE. Said node(s) for communication with the wireless communication network may be named external node(s) and may be considered not part of the wireless communication network but e.g. be comprised in another network and/or communication via another network, e.g. the external network 200, e.g. the Internet. Said node(s) for communication with the wireless communication network may be providing a service to the wireless communication network. These node(s) may correspond to the external node(s) 201 , such as an external management node and/or be distributed nodes, e.g. comprised in a so called computer cloud, or simply cloud, e.g. the cloud 202, which may provide a so called cloud service that may be configured to fully or partly carry out the method.

As realized from the above, it may be preferred that the actions are performed by a eNB, e.g. the first network node 1 10a, which therefore in the following may be used as main but non-limiting example of a node carrying out the actions. Note that shown actions may be taken in any suitable order and/or be carried out fully or partly overlapping in time when this is possible and suitable. Dotted lines in the figure attempt to illustrate features that are not present in all embodiments.

Action 901

The node(s), typically a radio network node such as an eNB, e.g. the first network node 1 10a, may detect a conflict, such as described above, relating to cells having a same cell identity, or in other words, the node(s) may obtain or make an identification of said problem with identical cell identities. For example, the first network node 1 10a may detect there being a conflict.

This action may fully or partly correspond to actions 601 , 701 discussed above. Action 902

The node(s) obtains, e.g. receives fully or partly from another node or other nodes, and/or retrieves internally, information about which multiple cells that are having said same cell identity, i.e. having identical cell identities, and possibly also an identification of said problem with identical cell identities, e.g. the identification of the problem and the information about the cells may be obtained at the same time.

The present action may be performed in connection with or in response to action 901. For example, in embodiments based on the scenario of Figure 7, the first network node 110a may in connection with or in response to detecting the problem in action 901 , obtain the information about which multiple cells that are having said same cell identity. In other embodiments, based on the scenario of Figure 8, the node(s) carrying out the present action may be another node(s) than carrying out Action 901 , e.g. be the common node 130.

When the information is received from another node or nodes, this is typically from the nodes that provide the cells that are causing the conflict, e.g. by receiving PCI from eNBs providing the cells causing the conflict. The receipt of the information may be in response to requesting it, and for example in connection with handover or similar. The information received from said another node or nodes may comprise information about cell identities of other cells, e.g. cells of said another node or nodes, and neighbour cells of these other cells and/or neighbouring cells of the neighbour cells of these other cells.

For example, the first network node 110a may in the present action obtain information that the third cell 1 15c and the fifth cell 1 15e, provided by the second and third network nodes 1 10b-c, respectively, are cells that are having the same cell identity.

This action may fully or partly correspond to actions 601-602, 701 discussed above. Action 903

The node(s) selects at least one of said multiple cells to change cell identity. The node(s) performing this action is typically the same as performing action 902, e.g. eNB2 such as the first network node 110a in case of the scenario in Figure 7, or e.g. the common node 130 in case of the scenario in Figure 6.

In any case, the selection is based on one or more of the following criteria:

which among said multiple cells that is associated with the largest number of available cell identities, and

which among said multiple cells is having a largest number of neighbouring cells to to its neighbour cells, which neighbouring cells are having the same cell identity.

Information for making the selection based on said criteria, such as information about neighbour cells and neighbouring cells of neighbour cells, may already be available to the node(s) carrying out the present action, such as available to the common node 130 as in the scenario of Figure 6, or may have been requested and received, such as by the first network node 110a as in actions 702-705 of Figure 7.

Some examples:

The first network node 1 10a may in the present action obtain information that the third cell 1 15c and the fifth cell 1 15e, provided by the second and third network nodes 1 10b-c, respectively, are cells that are having the same cell identity, and based on the criteria come to the conclusion that the fifth cell 1 15e should change cell identity. This would thus result in a situation corresponding to the scenario in Figure 7. In another example, the first network node 110a may in the present action obtain information that its own first cell 1 15a, the third cell 115c and the fifth cell 1 15e are having the same cell identity, and based on the criteria come to the conclusion that the first cell 1 15a should change cell identity. This would thus correspond to the scenario in Figure 8.

This action may fully or partly correspond to actions 603, 702-706 discussed above.

Action 904

The node(s) may initiate, in response to the selection, change of a cell identity of one of the selected at least one cell to an available cell identity for that cell.

Initiate the change may comprise sending one or more commands or instructions to one or more network nodes managing the cell identity to be changed, including e.g. the network node, e.g. eNB, that is providing the selected cell, or to make such one or more commands or instructions to be sent.

For example, in case of the scenario of Figure 6 and if a cell of the second network node 1 10b was selected to change cell identity, the common network node 130 may in the present action initiate the change by ordering the second network node 110b to change its cell identity. If instead, for example in case of the scenario of Figure 7, a cell of the third network node 1 10c was selected to change cell identity, the first network node 1 10c may in the present action initiate the change by ordering the third network node 110c to change the cell identity.

Any of the actions above may fully or partly involve and/or be initiated and/or be triggered by another, e.g. external, entity or entities, such as device and/or system, than what may actually be carrying out the actions. Such initiation may e.g. be triggered by said another entity in response to a request from the wireless communication network 100 and/or in response to some event resulting from commutations and/or program code executing in said another entity or entities. Said another entity or entities may correspond to or be comprised in a so called computer cloud, or simply cloud, e.g. the cloud 201 , and/or communication with said another entity or entities may be accomplished by means of one or more cloud services provided by such cloud.

Above, the cell identity and cell identities are preferably Physical Cell Identities (PCI) and/or are typically limited to a certain maximal, or maximum, number of different cell identities, e.g. due to that a limited number of bits are assigned to indicate each cell identity. The cell identities are further typically used in the wireless communication network 100 in addition to other cell identities that are not, or at least less, limited in number and that typically are sufficient to be able to uniquely identify each cell of the wireless communication network, such as in the case of Eutran Cell Global Identities (ECGI). Such other cell identity is thus of larger size and the cell identities herein, such as PCI, are of smaller size, which is a reason they are used for certain purposes instead of said other cell identities, e.g. used for the purpose, or in the context, of handover between cells. As used herein, "cell" may refer to a cell as conventionally defined for a wireless communication network, such as in LTE, i.e. for a wireless communication network based on cells as in the case of the wireless communication network 100, sometimes referred to a cellular communications network. Such wireless communication network covers a geographical area which is divided into cell areas that corresponds to the cells. Each cell is provided and/or served by a radio network node, such as base station or eNB in LTE. In each cell area of a cell, a radio network node, e.g. the first network node 1 10a, is providing or serving the cell, e.g. the first cell 1 15a, by providing radio coverage that enable a communication device, e.g. the communication device 120, to be wirelessly served in the cell by the radio network node. The radio coverage is specifically associated with the cell in question, typically by being uniquely identifiable and/or differing from radio coverage associated with other cells, e.g. by means of one or more cell identities that identifies the cell. A radio network node may provide and/or serve multiple cells. A cell may thus be a geographical area where radio coverage is provided by radio network node or radio base station equipment at a certain site, e.g. base station site, or at remote locations e.g. using so called Remote Radio Units (RRU).

Further, as used herein, by a "neighbour" or "neighbouring cell" to a certain cell, is meant a directly adjacent cell to said certain cell, i.e. with no other cell located in-between, or in other words when it is possible for a mobile communication device to move from said certain cell directly to the neighbour cell without having to move via any other cell, e.g. being served in said certain cell and moving to and instead be served in the neighbour cell without having to move via and/or be served in any other cell located between said cells.

Moreover, as used herein, "available cell identifies" may refer to cell identities that can be assigned to a cell without causing another or further problem of multiple cells having the same cell identity. The available cell identities for a cell may be based on a complete set of cell identities, e.g. as given by and/or limited to said certain maximal number of different cell identities, with exclusion of one or more of the following, preferably all of the following:

All cell identities that are used by any other cell or cells, if any, of the wireless communication network, which other cell(s) are provided by the same node, such as radio network node or eNB, that is providing the cell.

All cell identities that are used by any neighbour cell of the cell.

All cell identities that are used by any neighbour cell of a neighbour cell of the cell.

Information above relating to a cell, neighbour cell(s) of this cell and neighbouring cell(s) to the neighbour cell(s), may be received from or by network nodes providing cells, e.g. eNBs. This communication may take place over or via specific interfaces for communication between such network nodes, e.g. a so called X2 interface that e.g. are used when eNBs provide the cells and in case of LTE. The information may be comprised in certain messages, such as one or more of the following messages, e.g. as described above: X2 Setup Request message(s), X2 Setup Response message(s), ENB

Configuration Update message(s), Neighbour Information Request message(s) and Neighbour Information Response message(s). These messages may e.g. be structured and/or comprise one or more such elements as disclosed elsewhere herein. The

Neighbour Information Request message may be a new type of message that may be sent by a network node, typically eNB, to neighbour cells in order to request information from these regarding the neighbour cells and neighbouring cells of the neighbour cells. The Neighbour Information Response message may be a new type of message that may be sent by a network node, typically eNB, to another network node, typically eNB, in response to that said network node has received a Neighbour Information Request message from said another network node. The Neighbour Information Response message should comprise information regarding the neighbour cells and neighbouring cells of the neighbour cells.

Figure 10 is a flow chart schematically illustrating embodiments of a method, performed by one or more nodes, e.g. the first network node 10a, the second network node 110b, the third network node 110c, the common node 130, the external node 201 and/or the cloud 202. The method is preferably performed by a radio network node and in the following the one or more nodes are exemplified by the first network node 1 10a. The method is for managing cell identities in a wireless communication network, e.g. the wireless communication network 100, such as a LTE network, when cells of the wireless communication network are having identical cell identities that cause a conflict such as described above. Said wireless communication network may be a LTE network and/or said cell identities may be Physical Cell Identities (PCI).

The method comprises the following actions, which actions may be taken in any suitable order and/or be carried out fully or partly overlapping in time when this is possible and suitable.

Action 1001

The first network node 1 10a obtains information identifying cells of the wireless communication network 100 that are having a same, first cell identity. The cells may e.g. be the first cell 1 15a, the third cell 1 15c and the fifth cell 1 15e.

This action may fully or partly correspond to actions 601-602, 701 , 902 discussed above. Action 1002

The first network node 1 10a selects a cell, e.g. the first cell 1 15a, of said cells to change cell identity to another, second cell identity.

Preferably only one cell is selected to change cell identity, and in fact there should preferably be one cell selected to change to said another, second cell identity, if more cells are selected to change to the same second cell identity then the same kind of problem will be created again.

In Action 1001 there was identified two or more cells that have the same first cell identity. In a typical first case these are two cells, and one of these cells is in the present action selected to change cell identity to said another second cell identity. In other cases there can be more than two cells identified to have the same first cell identity although it typically becomes less and less likely to happen the more cells there are. In another second case there can thus e.g. be three cells. However, in any case, in the present action the first network node 1 10a should select one cell of the cells with same identity to change identity to said another, second cell identity. If there are multiple cells selected to change cell identity these should not be selected to change identity to the same another, second cell identity since this would typically just cause a same kind of problem again.

The selection is based on one or more of the following:

which among said cells, i.e. among said two or more cells that are having identical cell identities, that is associated with a largest number of available cell identities, or in other words, which one or more cells among said cells are associated with a largest number of available cell identities;

and

which among said cells that is, or which one or more cells among said cells are, having a largest number of neighbouring cells to its neighbour cells, which neighbouring cells are having the same cell identity. There can be more than one cell that is having a largest number of neighbouring cells to its neighbour cells and which neighbouring cells have the same cell identity.

Note that if there are more than one cell that both the has the largest and same number of available cell identities, e.g. two cells that have 5 available cell identities, and these two cells also have the same largest number of neighbouring cells to its neighbour cells and which neighbouring cells have the same cell identity, e.g. these two cells have 2 such neighbouring cells, then any of these can be selected to change cell identity to said another, second cell identity. This selection can be random or following that some further criteria also is applied to make the selection.

Further, said available cell identities for the selected cell, e.g. the first cell 115a, may be based on a maximum number of different cell identities available for the selected cell, with exclusion of:

All cell identities that are used by other cell or cells provided by the same radio network node that is providing the selected cell. For example, all cell identities used by any further cell(s) (not shown in Figure 5) provided by the first network node 110a that is providing the first cell 1 15a.

All cell identities that are used by any neighbour cell of the selected cell. For example, all cell identities used by the second cell 115a and the fourth cell 115d that are neighbouring the first cell 1 15a.

All cell identities that are used by any neighbouring cell to neighbour cell, or cells, of the selected cell. Or in other words, all cell identities that are used by any cell that is neighbour cell of a least one cell that is neighbour cell of the selected cell. For example, all cell identities used by the third cell 15c and the fifth cell 1 15e that are neighbouring cells to the second cell 115a and the fourth cell 1 15d, which in turn are neighbouring the first cell 1 15a.

This action may fully or partly correspond to actions 603, 702-706, 903 discussed above.

Action 1003 The first network 110a may then initiate a change of cell identity of the selected cell, e.g. the first cell 115a, to one of available cell identities for the selected cell.

This action may fully or partly correspond to actions 605, 707, 904 discussed above. Figure 11 is a schematic block diagram for illustrating embodiments of a node

1100, or arrangement, may be configured to perform the method and actions discussed above in connection with Figure 10. The node 1100 thus be any one of the network nodes 1 10a-c, e.g. a radio network node or base station such a eNB in LTE, or the common node 130, e.g. a core network node and/or an internal management node, or the external node 201 , such as an external management node and/or be distributed nodes, e.g.

comprised in the cloud, and/or may be or correspond to a so called Domain Manager (DM) or Network Manager (NM) in LTE.

Hence, the node 1100 may comprise:

A processing module 1101 , such as a means, one or more hardware modules, including e.g. one or more processors, and/or one or more software modules for performing said method and/or actions.

A memory 1102, which may comprise, such as contain or store, a computer program 1103. The computer program comprises 'instructions' or 'code' directly or indirectly executable by the respective node so that it performs said method and/or actions. The memory 1 102 may comprise one or more memory units and may be further be arranged to store data, such as configurations and/or applications involved in or for performing functions and actions of embodiments herein.

A processing circuit 1104 as an exemplifying hardware module and may comprise or correspond to one or more processors. In some embodiments, the

processing module 1101 may comprise, e.g. 'is embodied in the form of or 'realized by' the processing circuit 1104. In these embodiments, the memory 1102 may comprise the computer program 1103 executable by the processing circuit 1104, whereby the node 1 100 is operative, or configured, to perform said method and/or actions.

An Input/Output (I/O) module 1105, configured to be involved in, e.g. by performing, any communication to and/or from other units and/or nodes, such as sending and/or receiving information to and/or from other nodes or devices. The I/O module 1 105 may be exemplified by an obtaining, e.g. receiving, module and/or a sending module, when applicable. The node 1100 may also comprise other exemplifying hardware and/or software module(s), which module(s) may be fully or partly implemented by the processing circuit 1 104.

For example, the node 1100 may further comprise an obtaining module 1106 5 and/or a selecting module 1107 and/or an initiating module 1108.

Hence, the node 1100 and/or the processing module 1 101 and/or the processing circuit 1104 and/or the I/O module 1105 and/or the obtaining module 1 106, are operative, or configured, to obtain the information identifying the cells that are having said same, first cell identity.

10 Further, the node 1100 and/or the processing module 1 101 and/or the processing circuit 1104 and/or selecting module 1107, are operative, or configured, to select the cell to change cell identity to said another, second cell identity.

In some embodiments, the node 1100 and/or the processing module 1101 and/or the processing circuit 1104 and/or initiating module 1108, are operative, or configured, to

15 initiate said change of cell identity of the selected cell.

Figures 12a-c are schematic drawings illustrating embodiments relating to a computer program that may be the computer program 1 103, and that comprises instructions that when executed by the processing circuit 1104 causes the node 1 100 to

20 perform the method as described above.

In some embodiments there is provided a computer program product, i.e. a carrier or data carrier, e.g. comprising a computer-readable medium and/or the computer program. By carrier and/or computer readable medium may be excluded a transitory, propagating signal and the carrier and/or computer readable medium may

25 correspondingly be named non-transitory carrier and/or computer readable medium. Non- limiting examples of the computer-readable medium is a memory card or a memory stick 1201 as in Figure 12a, a disc storage medium 1202 such as a CD or DVD as in Figure 12b, a mass storage device 1203 as in Figure 12c. The mass storage device 1203 is typically based on hard drive(s) or Solid State Drive(s) (SSD). The mass storage device

30 1203 may be such that is used for storing data accessible over a computer network 1204, e.g. the Internet or a Local Area Network (LAN).

The computer program 1 103 may furthermore be provided as a pure computer program or comprised in a file or files. The file or files may be stored on the computer- readable medium and e.g. available through download e.g. over the computer network

35 1205, such as from the mass storage device 1204 via a server. The server may e.g. be a web or File Transfer Protocol (FTP) server. The file or files may e.g. be executable files for direct or indirect download to and execution on the node 1 100 for carrying out the method, e.g. by the processing circuit 1 104, or may be for intermediate download and compilation to make them executable before further download and execution causing the node(s) to perform the method as described above.

Note that any processing module(s) mentioned in the foregoing may be

implemented as a software and/or hardware module, e.g. in existing hardware and/or as an Application Specific integrated Circuit (ASIC), a field-programmable gate array (FPGA) or the like. Also note that any hardware module(s) and/or circuit(s) mentioned in the foregoing may e.g. be included in a single ASIC or FPGA, or be distributed among several separate hardware components, whether individually packaged or assembled into a System-on-a-Chip (SoC).

Those skilled in the art will also appreciate that the modules and circuitry discussed herein may refer to a combination of hardware modules, software modules, analogue and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in memory, that, when executed by the one or more processors make the first node and the second node to be configured to and/or to perform the above-described methods, respectively.

Identification, e.g. by any identifier herein, may be implicit or explicit. The

identification may be unique in the wireless communication network 100 or at least in a part or some area thereof.

The term "network", or simply "NW", as used herein typically, as should be realized without any information on the contrary, refer to the wireless communication network 100.

The term "network node" as used herein may as such refer to any type of radio network node (described below) or any network node, which may communicate with at least a radio network node. Examples of such network nodes include any radio network node stated above, a core network node, Operations & Maintenance (O&M), Operations Support Systems (OSS), Self Organizing Network (SON) node, positioning node etc.

The term "radio network node" as used herein may as such refer to any type of network node serving a wireless device and/or that are connected to other network node(s) or network element(s) or any radio node from which a wireless device receives signals. Examples of radio network nodes are Node B, Base Station (BS), Multi-Standard Radio (MSR) node such as MSR BS, eNB, eNodeB, network controller, RNC, Base Station Controller (BSC), relay, donor node controlling relay, Base Transceiver Station (BTS), Access Point (AP), transmission points, transmission nodes, nodes in distributed antenna system (DAS) etc.

The term "communication device" or "wireless device" as used herein, may as such refer to any type of device arranged to communicate, e.g. with a radio network node, in a wireless, cellular and/or mobile communication system, such as the wireless

communication network 100, and may thus be a wireless communication device.

Examples include: target devices, device to device UE, device for Machine Type of Communication (MTC), MTC device, machine type UE or UE capable of machine to machine (M2M) communication, Personal Digital Assistant (PDA), iPAD, Tablet, mobile terminals, smart phone, Laptop Embedded Equipment (LEE), Laptop Mounted Equipment (LME), Universal Serial Bus (USB) dongles etc. While said terms are used frequently herein for convenience, or in the context of examples involving other 3GPP nomenclature, it must be appreciated that the term as such is non-limiting and the teachings herein apply to essentially any type of wireless device.

The term "node" as used herein may as such refer to any type of network node(s) or device(s), such as described above.

Note that although terminology used herein may be particularly associated with and/or exemplified by certain cellular communication systems, wireless communication networks etc., depending on terminology used, such as wireless communication networks based on 3GPP, this should as such not be seen as limiting the scope of the

embodiments herein to only such certain systems, networks etc.

As used herein, the term "memory" may refer to a hard disk, a magnetic storage medium, a portable computer diskette or disc, flash memory, random access memory (RAM) or the like. Furthermore, the memory may be an internal register memory of a processor.

Also note that any enumerating terminology such as first network node, second network node, first base station, second base station, or similar, that may have been used herein, as such should be considering non-limiting and the terminology as such does not imply a certain hierarchical relation. Without any explicit information in the contrary, naming by enumeration should be considered merely a way of accomplishing different names.

Claims

A method, performed by one or more nodes (110a; 1 10b; 110c; 130; 201 ; 202), for managing cell identities in a wireless communication network (100) when cells (115a, 115c, 1 15e) of the wireless communication network (100) are having identical cell identities that cause a conflict, wherein the method comprises:

- obtaining (601-602; 701; 902; 1001) information identifying cells (1 15a, 1 15c, 115e) of the wireless communication network (100) that are having a same, first cell identity; and

- selecting (603; 702-706; 903; 1002) a cell (115a) of said cells (1 15a, 1 15c, 115e) to change cell identity to another, second cell identity, wherein the selection is based on one or more of the following:

which among said cells (1 15a, 115c, 115e) that is associated with a largest number of available cell identities, and

which among said cells (1 15a, 115c, 1 15e) that is having a largest number of neighbouring cells to its neighbour cells, which

neighbouring cells are having the same cell identity.

The method as claimed in claim 1 , wherein the method further comprises:

- initiating (605; 707; 904; 1003) a change of cell identity of the selected cell (115a) to one of available cell identities for the selected cell (115a).

The method as claimed in any one of claims 1-2, wherein the method is performed by a radio network node (110a).

The method as claimed in any one of claims 1-3, wherein said available cell identities for the selected cell (1 15a) are based on:

a maximum number of different cell identities available for the selected cell (115a), with exclusion of:

all cell identities that are used by other cell or cells provided by the same radio network node (110a) that is providing the selected cell (1 15a), all cell identities that are used by any neighbour cell (115b, 115d) of the selected cell (1 15a), and all cell identities that are used by any neighbouring cell (1 15c, 115e) to neighbour cell or cells (115b, 1 15d) of the selected cell (115a).

The method as claimed in any one of claims 1-4, wherein said cell identities are Physical Cell Identities, "PCI", and/or the wireless

communication network (100) is a Long Term Evolution, "LTE", network.

A computer program (1103) comprising instructions that when executed by a node (1 10a; 110b; 1 10c; 130; 201) causes the node (110a; 1 10b; 110c; 130; 201) to perform the method according to any one of claims 1-5.

A computer readable medium (1201 ; 1202; 1203) comprising the computer program (1103) according to claim 6.

A node (1 100; 1 10a; 110b; 1 10c; 130; 201) for managing cell identities in a wireless communication network (100) when cells (1 15a, 115c, 115e) of the wireless communication network (100) are having identical cell identities that causes a conflict, wherein said node (1 10a; 110b; 1 10c; 130; 201) is configured to:

obtain (601-602; 701 ; 902; 1001) information identifying cells (1 15a, 1 15c, 115e) of the wireless communication network (100) that are having a same, first cell identity; and

select (603; 702-706; 903; 1002) a cell (1 15a) of said cells (115a, 1 15c, 1 15e) to change cell identity to another, second cell identity, wherein the selection is based on one or more of the following:

which among said cells (1 15a, 115c, 1 15e) that is associated with a largest number of available cell identities, and

neighbouring cells are having the same cell identity.

The node (1100; 1 10a; 110b; 110c; 130; 201) as claimed in claim 8, further configured to:

initiate (605; 707; 904; 1003) a change of cell identity of the selected cell (1 15a) to one of available cell identities for the selected cell (1 15a).

The node (1100; 1 10a; 110b; 1 10c; 130; 201 ) as claimed in any one of claims 8-9, wherein the node (1100; 110a; 1 10b; 110c; 130; 201) is a radio network node (110a). 1. The node (1100; 1 10a; 110b; 1 10c; 130; 201) as claimed in any one of claims 8-10, wherein said available cell identities for the selected cell (1 15a) are based on:

all cell identities that are used by other cell or cells provided by the same radio network node (110a) that is providing the selected cell (115a), all cell identities that are used by any neighbour cell of the respective cell (115a; 1 15c; 1 15e), and

all cell identities that are used by any neighbouring cell (1 15c, 115e) to neighbour cell or cells (1 15b, 115d) of the selected cell (115a).

The node (1100; 1 10a; 110b; 1 10c; 130; 201) as claimed in any one of claims 8-1 1 , wherein said cell identities are Physical Cell Identities, "PCI" and/or the wireless communication network (100) is a Long Term

Evolution, "LTE", network.

A node (1 100; 1 10a; 110b; 1 10c; 130; 201) for managing cell identities in a wireless communication network (100) when cells (1 15a, 115c, 115e) of the wireless communication network (100) are having identical cell identities that causes a conflict, wherein said node (1 10a; 1 10b; 1 10c; 130; 201) comprises:

an obtaining module (1106) configured to obtain (601-602; 701 ; 902;

1001) information identifying cells (1 15a, 115c, 115e) of the wireless communication network (100) that are having a same, first cell identity; and

a selecting module (1107) configured to select (603; 702-706; 903;

1002) a cell (115a) of said cells (1 15a, 1 15c, 1 15e) to change cell identity to another, second cell identity, wherein the selection is based on one or more of the following:

neighbouring cells are having the same cell identity.

The node (1100; 1 10a; 110b; 1 10c; 130; 201) as claimed in claim 13, further comprising:

an initiating module (1108) configured to initiate (605; 707; 904; 1003) a change of cell identity of the selected cell (1 15a) to one of available cell identities for the selected cell (115a).

The node (1100; 1 10a; 110b; 1 10c; 130; 201) as claimed in any one of claims 13-14, wherein the node (1 100; 110a; 110b; 1 10c; 130; 201) is a radio network node (110a).

The node (1100; 1 10a; 1 10b; 1 10c; 130; 201) as claimed in any one of claims 13-15, wherein said available cell identities for the selected cell (1 15a) are based on:

all cell identities that are used by other cell or cells provided by the same radio network node (1 10a) that is providing the selected cell (115a), all cell identities that are used by any neighbour cell of the respective cell (115a; 1 15c; 1 15e), and

all cell identities that are used by any neighbouring cell (1 15c, 1 15e) to neighbour cell or cells (1 15b, 115d) of the selected cell (115a).

The node (1100; 1 10a; 110b; 1 10c; 130; 201) as claimed in any one of claims 13-16, wherein said cell identities are Physical Cell Identities, "PCI", and/or the wireless communication network (100) is a Long Term

Evolution, "LTE", network. A node (1 100; 1 10a; 110b; 1 10c; 130; 201) for managing cell identities in a wireless communication network (100) when cells (1 15a, 115c, 115e) of the wireless communication network (100) are having identical cell identities that causes a conflict, wherein said node (1 10a; 1 10b; 1 10c; 130; 201) comprises one or more processors and a memory containing instructions executable by said one or more processors whereby said node (1100; 1 10a; 110b; 1 10c; 130; 201) is operative to:

which among said cells (115a, 1 15c, 1 15e) that is having a largest number of neighbouring cells to its neighbour cells, which

neighbouring cells are having the same cell identity. 19. The node (1100; 1 10a; 110b; 1 10c; 130; 201) as claimed in claim 18,

wherein said memory contains instructions executable by said one or more processors whereby said node (1100; 1 10a; 110b; 1 10c; 130; 201 ) is operative to:

initiate (605; 707; 904; 1003) a change of cell identity of the selected cell (1 15a) to one of available cell identities for the selected cell

(1 15a).

The node (1100; 1 10a; 110b; 1 10c; 130; 201) as claimed in any one of claims 18-19, wherein the node (1100; 1 10a; 110b; 1 10c; 130; 201) is a radio network node (110a).

The node (1100; 1 10a; 110b; 1 10c; 130; 201) as claimed in any one of claims 18-20, wherein said available cell identities for the selected cell (1 15a) are based on: a maximum number of different cell identities available for the selected cell (115a), with exclusion of:

all cell identities that are used by any neighbouring cell (1 15c, 1 15e) to neighbour cell or cells (115b, 1 15d) of the selected cell (115a). 22. The node (1100; 1 10a; 110b; 1 10c; 130; 201) as claimed in any one of claims 18-21 , wherein said cell identities are Physical Cell Identities, "PCI", and/or the wireless communication network (100) is a Long Term

Evolution, "LTE", network.