WO2016080875A1

WO2016080875A1 - Detection of neighbor cell relation(s) based on connection drop events and connection establishment events

Info

Publication number: WO2016080875A1
Application number: PCT/SE2014/051379
Authority: WO
Inventors: Bo Hellander; Sofia BRISMAR; Darine ZAMBRANO MERCADO; Mikael SÖDERSTRÖM; Lena MELIN
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2014-11-19
Filing date: 2014-11-19
Publication date: 2016-05-26

Abstract

There is provided a method for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network. The method comprises collecting (S1) information related to connection drop events, wherein the information, for each connection drop event, includes information about the identity of the wireless device involved in the connection drop and cell information about cell(s) to which the wireless device was connected at connection drop. The method also comprises collecting (S2) information related to connection establishment events, wherein the information, for each connection establishment event, includes information about the identity of the wireless device involved in the connection establishment and cell information about cell(s) to which the wireless device connected at connection establishment. Further, the method comprises correlating (S3) a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the collected information. The method also comprises identifying (S4), based on cell information related to the correlated events, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment.

Description

DETECTION OF NEIGHBOR CELL RELATION(S) BASED ON CONNECTION DROP EVENTS AND CONNECTION ESTABLISHMENT EVENTS

TECHNICAL FIELD

The proposed technology generally relates to a method and corresponding apparatus for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network, and a corresponding management system and network node, as well as a corresponding computer program and computer-program product.

BACKGROUND

An important feature in modern and future cellular communication networks, in general, is related to the management of neighbor cell relations. By way of example, the management and detection of neighbor cell relations can be seen as an important cornerstone in order to achieve efficient Self Organized Networks, SON. Moreover, if such neighbor cell relations can be automatically detected/generated this would, aside from lowering installation and operation costs for operators, also improve the Key Performance Indicator, KPI, called retainability. The technology behind automatically generated neighbor cell relations is generally referred to as Automatic Neighbor Relations, ANR, and such neighbor cell relations are often maintained in one or more databases; for example in a neighbor cell list or, equivalently, a neighbor cell table or other suitable representation.

It would be highly desirable if a network node had an at least satisfactory knowledge about the neighbor cell relations between the cells within the network since this would make a lot of the operations that are managed by, or under the control of, the network node more robust. For example, some standardized network solutions even require information of neighbor cell relations for proper network operation. A possible example of an operation that would benefit from neighbor cell information is the handover of a User Equipment between different cells. Knowledge about neighbor cell relations would, for example, reduce the amount of dropped calls during handover. It would also facilitate the management of the network, for example, by making manually performed additions of neighbor cell relations more or less redundant. Since a cellular communication network or network environment in general is gradually evolving over time, new neighbor cells will frequently be added to the cellular communication network and new interference patterns among the cells will emerge. In order for the network node to maintain relevant information about neighbor cell relations, there will be a need for solutions that enables the network to update its knowledge about neighbor cell relations between cells by detecting missing or undefined neighbor cell relations.

A problem is that manual configuration of neighbor cell relations takes a lot of time for operators. In light of this, the design of efficient mechanisms that are able to automatically detect missing neighbor cell relations has become increasingly important and several different solutions for so-called Automatic Neighbor Relations, ANR, have been proposed.

In one of the known methods, used in Wideband Code Division Multiple Access, WCDMA, the User Equipment, UE, reports detected cells to the Radio Network Controller, RNC. The RNC may order the UE to measure and report missing cells, i.e. cells that are not already defined in a neighbor cell list. The order is sent to the UE in a MEASUREMENT CONTROL message together with other measurement control information such as event/reporting criteria, neighbor cell list, measurement quantities, and measurement command(s). The UE will apply the same measurement control information on all cells, i.e. both detected set cells and cells listed in a neighbor cell list. If a detected set cell triggers a measurement event the UE will send a MEASUREMENT REPORT message to the RNC. The RNC will evaluate the MEASUREMENT REPORT message to find out if the reported cell is already defined as a neighbor or not. If not, it can be added as a new neighbor relation.

However, this method does not work for certain radio access technologies and cells. WCDMA supports intra-frequency detected set cells from Rel-99 and inter-frequency detected set cells from Rel-10. Reporting of detected inter-frequency cells is an optional feature in the UE.

ANR logging has been proposed as an optional feature to detect missing neighbor relations in 3GPP Rel-10 [1 ]. When the feature is activated the User Equipment, UE, will measure and record detected set cells in Idle mode, UTRAN Registration Area Paging Channel, URA_PCH, state and Cell Paging Channel, CELL_PCH, state. The report can be retrieved by the Radio Network Controller, RNC, when the UE becomes active, i.e. when the UE is in Cell Dedicated Channel, CELL_DCH, and Cell Forward Access Channel, CELL_FACH, state. Each report contains up to four missing relations detected by the UE. The UE may log and report Intra-frequency, IAF, Inter-frequency, IEF, Long Term Evolution, LTE and Global Systems for Mobile communications, GSM, relations.

As indicated, the UE support for ANR logging is an optional 3GPP feature and thus it is difficult to predict how many UEs that will actually support ANR logging in the future.

Some existing ANR tools are built on post-processing of statistics, for example by collecting handover attempt/success statistics and detected cells reported by UEs during a certain recording time. This gives a slow solution that does not fulfil the requirements for quick integration of e.g. added Radio Base Stations, RBSs.

A problem, at least for IAF and IEF, with building ANR based on UE reporting of detected set cells is that the UE will only report Scrambling Code (SC) and not cell identity. This means that it is not possible to uniquely identify the detected cell in the RNC if more cells are using the same SC.

Another problem, at least for IEF, is that 3GPP support for inter-frequency detected cell reporting was introduced in Rel-10 as an optional feature, and the feature is not yet implemented or is not expected to be implemented in the near future by UE chipset vendors. Yet another problem, at least for IEF, with building ANR based on UE reporting of detected set cells is that the UE must be in compressed mode in order to measure and report detected set cells. Compressed mode consumes additional downlink, DL, power and reduces uplink, UL, coverage as well as UL/DL data throughput. Hence the time in compressed mode should be limited, e.g. only activated when there is a need to perform an Inter-frequency or GSM handover due to bad coverage.

Also for IAF measurements, 3GPP has specified that the UE is allowed to take considerable time to report lAF-detected set neighbors. A problem with ANR measurement reports sent by the UE is that the 3GPP support introduced in Rel-10 is merely an optional feature in the UE, and the feature is not yet implemented or is not expected to be implemented in the near future by UE chipset vendors. There is thus a general demand for improved solutions for detection of neighbor cell relations.

SUMMARY It is an object to provide a method for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network.

It is another object to provide an apparatus configured to detect a neighbor cell relation between cells in a communication environment including at least one cellular communication network.

It is also an object to provide a management system in a communication network. It is yet another object to provide a network node in a communication network.

Still another object is to provide a corresponding computer program and computer- program product. It is also an object to provide an apparatus for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network.

These and other objects are met by embodiments of the proposed technology.

According to a first aspect, there is provided a method for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network. The method comprises collecting information related to connection drop events, wherein the information, for each connection drop event, includes information about the identity of the wireless device involved in the connection drop and cell information about cell(s) to which the wireless device was connected at connection drop. The method also comprises collecting information related to connection establishment events, wherein the information, for each connection establishment event, includes information about the identity of the wireless device involved in the connection establishment and cell information about cell(s) to which the wireless device connected at connection establishment. Further, the method comprises correlating a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the collected information related to connection drop events and connection establishment events. The method also comprises identifying, based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment.

According to a second aspect, there is provided an apparatus configured to detect a neighbor cell relation between cells in a communication environment including at least one cellular communication network. The apparatus is configured to collect information related to connection drop events, wherein the information, for each connection drop event, includes information about the identity of the wireless device involved in the connection drop and cell information about cell(s) to which the wireless device was connected at connection drop. The apparatus is also configured to collect information related to connection establishment events, wherein the information, for each connection establishment event, includes information about the identity of the wireless device involved in the connection establishment and cell information about cell(s) to which the wireless device connected at connection establishment. Further, the apparatus is configured to correlate a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the collected information related to connection drop events and connection establishment events. The apparatus is also configured to identify, based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment.

According to a third aspect, there is provided a management system in a communication network, wherein the management system comprises an apparatus according to the second aspect. According to a fourth aspect, there is provided a network node in a communication network, wherein the network node comprises an apparatus according to the second aspect.

According to a fifth aspect, there is provided a computer program comprising instructions, which when executed by at least one processor, cause the at least one processor to:

read information related to connection drop events,

wherein the information, for each connection drop event, includes information about the identity of a wireless device involved in the connection drop and cell information about cell(s) to which the wireless device was connected at connection drop;

read information related to connection establishment events, wherein the information, for each connection establishment event, includes information about the identity of the wireless device involved in the connection establishment and cell information about cell(s) to which the wireless device connected at connection establishment;

- correlate a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the information related to connection drop events and connection establishment events; and

identify, based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment. According to a sixth aspect, there is provided a computer program product comprising a computer-readable medium having stored thereon a computer program according to the fifth aspect.

According to a seventh aspect, there is provided an apparatus for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network. The apparatus comprises a first collecting module for collecting information related to connection drop events, wherein the information, for each connection drop event, includes information about the identity of the wireless device involved in the connection drop and cell information about cell(s) to which the wireless device was connected at connection drop. The apparatus also comprises a second collecting module for collecting information related to connection establishment events, wherein the information, for each connection establishment event, includes information about the identity of the wireless device involved in the connection establishment and cell information about cell(s) to which the wireless device connected at connection establishment. Further, the apparatus comprises a correlation module for correlating a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the information related to connection drop events and connection establishment events. The apparatus also comprises an identification module for identifying, based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment.

In this way, the proposed technology enables efficient detection of neighbor cell relations. The proposed technology may be used to identify missing and/or undefined relations between cells on the same frequency, or on different frequencies, between cells of the same radio access technology or different radio access technologies, between cells of the same base station or different base stations, between cells associated with the same base station controller or different base station controllers, between cells associated with the same radio network controller or different radio network controllers, and/or between cells associated with the same operation and support system or different operation and support systems.

Other advantages will be appreciated when reading the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments, together with further objects and advantages thereof, may best be understood by making reference to the following description taken together with the accompanying drawings, in which:

FIG. 1 is a schematic flow diagram illustrating an example of a method for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network.

FIG. 2 is a schematic diagram illustrating an example overview of a network architecture including an access network part, a core network part and an operation and support and/or management system part according to an embodiment. FIG. 3 is a schematic diagram illustrating an example of detection of neighbor cell relation(s) based on a call drop event and a corresponding call setup event in an inter-RNC scenario.

FIG. 4 is a schematic simplified diagram illustrating an example of detection of neighbor cell relation(s) in an intra-RNC scenario.

FIG. 5 is a schematic simplified diagram illustrating an example of detection of neighbor cell relation(s) between cells of different radio access technologies.

FIG. 6 is a schematic simplified diagram illustrating another example of detection of neighbor cell relation(s) between cells of different radio access technologies. FIG. 7 is a schematic signaling diagram illustrating an example of the correlation of a call drop event and a call establishment event in an inter-RNC scenario corresponding to that of FIG. 3.

FIG. 8 is a schematic diagram illustrating an example of registered connection drop events and connection establishment events and the correlation of events for detecting possible neighbor cell relation(s).

FIG. 9 is a schematic block diagram illustrating an example of an apparatus configured to detect a neighbor cell relation between cells in a communication environment including at least one cellular communication network.

FIG. 10 is a schematic block diagram illustrating an example of a management system and/or a network node in a communication network comprising an apparatus of FIG. 9.

FIG. 1 1 is a schematic block diagram illustrating an example of a computer- implementation of the proposed technology according to an embodiment. FIG. 12 is a schematic computer flow diagram according to an embodiment.

FIG. 13 is a schematic block diagram illustrating an example of an apparatus for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network.

DETAILED DESCRIPTION

Throughout the drawings, the same reference designations are used for similar or corresponding elements.

As used herein, the non-limiting terms "wireless device" and "User Equipment, UE" may refer to a mobile phone, a cellular phone, a Personal Digital Assistant, PDA, equipped with radio communication capabilities, a smart phone, a laptop or Personal Computer, PC, equipped with an internal or external mobile broadband modem, a tablet PC with radio communication capabilities, a target device, a device to device UE, a machine type UE or UE capable of machine to machine communication, iPAD, customer premises equipment, CPE, laptop embedded equipment, LEE, laptop mounted equipment, LME, USB dongle, a portable electronic radio communication device, a sensor device equipped with radio communication capabilities or the like. In particular, the term "wireless device" and "UE" should be interpreted as non- limiting terms comprising any type of wireless device communicating with a radio network node in a cellular or mobile communication system or any device equipped with radio circuitry for wireless communication according to any relevant standard for communication within a cellular or mobile communication system.

As used herein, the non-limiting term "network node" may refer to base stations, network control nodes such as network controllers, radio network controllers, base station controllers, and the like. In particular, the term "base station" may encompass different types of radio base stations including standardized base stations such as Node Bs, or evolved Node Bs, eNBs, and also macro/micro/pico radio base stations, home base stations, also known as femto base stations, relay nodes, repeaters, radio access points, base transceiver stations, BTSs, and even radio control nodes controlling one or more Remote Radio Units, RRUs, or the like.

FIG. 1 is a schematic flow diagram illustrating an example of a method for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network. The method basically comprises the steps of:

S1 : collecting information related to connection drop events,

wherein the information, for each connection drop event, includes information about the identity of the wireless device involved in the connection drop and cell information about cell(s) to which the wireless device was connected at connection drop. S2: collecting information related to connection establishment events,

wherein the information, for each connection establishment event, includes information about the identity of the wireless device involved in the connection establishment and cell information about cell(s) to which the wireless device connected at connection establishment.

S3: correlating a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the collected information related to connection drop events and connection establishment events.

S4: identifying, based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment.

The proposed technology thus provides an efficient way of detecting neighbor cell relation(s). In this way, it is possible to provide an efficient ANR solution. Such a solution for automatically creating neighbor relations is very useful for mobile system operators since they save efforts for operation and maintenance.

For example, the collected information related to connection drop events and connection establishment events may be evaluated by comparing, event-by-event, the information about the identity of the wireless device involved in a connection drop with the information about the identity of the wireless device involved in a connection establishment until a match is detected, thereby correlating a connection drop event and a connection establishment event relating to the same wireless device.

In a particular example, the information, for each connection drop event, also includes a time stamp related to the connection drop event, and the information, for each connection establishment event, also includes a time stamp related to the connection establishment event. The step of identifying neighbor cell relation(s) based on cell information related to the correlated connection drop event and connection establishment event relating to the same wireless device may then be performed if the time stamp of the connection drop event and the time stamp of the connection establishment event are within a time interval.

It should be understood that for a fair amount of the connection drops, the wireless device may attempt to establish a new connection before the network has noticed that the old connection has been dropped. In other words, it may be the case that the connection establishment event is time-stamped as occurring before the connection drop event. This does not affect the general principles of the proposed technology, but implies that the time difference between drop to setup may be positive or negative in value.

Another way of implying a time limitation, without the need for time-stamping, is to keep the database of registered events updated so as to hold events within a moving time window of a given or configurable length. Alternatively, no time limitations are applied in order to detect as many candidate neighbor cell relations as possible.

According to a particular embodiment, for Wideband Code Division Multiple Access, WCDMA, systems, the cell information about cell(s) to which the wireless device was connected at connection drop includes information about cell(s) in the active set at connection drop, and the cell information about cell(s) to which the wireless device connected at connection establishment includes information about cell(s) in the active set at connection establishment.

By way of example, the connection establishment events may be triggered by call setups and/or connection-related registrations.

As indicated, the identified neighbor cell relation(s) may be regarded as candidate neighbor cell relation(s). Typically, the candidate relations may be evaluated before they are actually set in the neighbor cell lists.

By way of example, the method may beneficially be performed for detecting a neighbor cell relation between cells in a WCDMA network. It should though be understood that the proposed technology is not limited thereto, and the general principles may be applied for any radio access technology and/or combination of technologies, as exemplified below.

For a better understanding of the network components that may be involved in the procedures of at least one embodiment of the proposed technology, a non-limiting example of a network architecture including an access network part, a core network part and an operation and support and/or management system part will now be described with reference to FIG. 2. In the particular example of FIG. 2, the access network part may relate to one or more than one radio access technology. As an example, the overall network may include one or more of the following radio access technologies: GRAN/GERAN, UTRAN and E-UTRAN, where GRAN stands for GSM Radio Access Network, GERAN stands for GSM EDGE Radio Access Network, UTRAN stands for UMTS Terrestrial Radio Access Network and E-UTRAN stands for Evolved UTRAN. It should be understood that the proposed technology may also relate to other radio access technologies.

The radio access network(s) may serve a number of UEs 10-1 to 10-/V, where N is an integer equal to or greater than 1 .

In G(E)RAN, the access network is based on one or more Radio Base Stations, RBSs, 20 connected to one or more Base Station Controllers, BSCs 30. The BSC 30 may be connected to the core network, e.g. to a Mobile Switching Center, MSC, 70, and a Serving GPRS Support Node, SGSN 80.

In UTRAN, the access network is based on one or more NodeBs, 40-1 to 40-3, connected to one or more Radio Network Controllers, RNCs 50-1 , 50-2. The RNCs 50 may be connected to the core network, e.g. to the MSC 70 and the SGSN 80. The SGSN 80 may further be connected to a Gateway GPRS Support Node, GGSN, 90, according to well-accepted standards. In E-UTRAN, the access network is based on one or more eNodeBs 60, which may be connected to the core network, e.g. to a Mobility Management Entity, MME, 100. The MME 100 may be connected to a Gateway, GW 1 10, according to well-accepted standards. The SGSN 80 may also be connected to the MME 100 and/or the GW 1 10.

The core network may be connected to an Operations and Support System, OSS, 120-1 . There may be more than one core network involved, and each additional core network is then normally connected to its own OSS, 120-2. The OSS systems 120-1 and 120-2 may be connected to a Network Management System, NMS, 130.

Typically, all network nodes may be connected, directly or indirectly, to the relevant OSS. Optionally, there may a direct interface between the RNC 50 and the BSC 30, e.g. in an integrated RNC-BSC node, as indicated by the dashed lines. Optionally, there may a direct interface between the RNC 50 and the eNodeB 60, e.g. in an integrated RNC-eNodeB node, as indicated by the dashed lines.

Proprietary solutions for signaling are also possible. The proposed technology is generally applicable for detecting various neighbor cell relations, including at least one of:

an intra-frequency relation,

an inter-frequency relation,

an intra-radio access technology relation,

- an inter-radio access technology relation,

an intra-base station relation,

an inter-base station relation,

an intra-base station controller relation,

an inter-base station controller relation,

- an intra-radio network controller relation,

an inter-radio network controller relation,

an intra-operation and support system relation, and

an inter-operation and support system relation. In other words, the proposed technology may be used to identify missing and/or undefined relations between cells on the same frequency, or on different frequencies, between cells of the same radio access technology or different radio access technologies, between cells of the same base station or different base stations, between cells associated with the same base station controller or different base station controllers, between cells associated with the same radio network controller or different radio network controllers, and/or between cells associated with the same operation and support system or different operation and support systems and thus usually different core networks. By way of example, the method may be performed by a network node or management system in the communication network. For example, the method may be performed by the network management system, NMS, an operation and support system, OSS, a radio network controller, RNC, a base station controller, BSC, or an evolved base station, eNode B.

After a dropped call or connection, wireless devices such as User Equipments, UEs, will typically attempt to re-establish the connection. This is especially true for packet-based calls or connections in case the UE has data to send in its data buffer, but could also be the case also for circuit-switched services.

For example, by collecting events for connection drops and logging UE identity such as International Mobile Subscriber Identity, IMSI, Temporary Mobile Subscriber Identity, TMSI, Packet Temporary Mobile Subscriber Identity, P-TMSI, or International Mobile Equipment Identity, IMEI, Radio Access Technology, RAT, cell(s) and/or time as well as events for connection setups and logging UE identity such as IMSI, TMSI, P-TMSI or IMEI, radio access technology, cell(s) and/or time, and correlating these two types of events, the inventors have realized that it is possible to find candidates for missing cell relations. As an example, if a call drops in cell A and then re-establishes in cell B shortly after, a neighbor relation from cell A to cell B might be useful.

Correlating connection drops/call drops and connection establishments/call setups as a basis for finding missing neighbor relations is advantageous compared to using UE measurements and detected set cells. For example, it does not depend on any specific UE functionality. It does not require the UE to perform measurements in active mode, which consumes DL power and reduces quality since UE needs to be in compressed mode. It gives quick results. It may uniquely identify the source and target cell, considering that, e.g. in WCDMA, lAF/IEF measurement reporting from the UE is limited to identification of PSC which is not unique in an RNC or network. The proposed technology may also work in scenarios where the radio conditions degrade fast and the UE therefore has no time to perform necessary detected set measurements. As indicated, it can be used to identify missing neighbor relations between cells on the same radio access technology and/or frequency, between cells on different frequencies and/or different radio access technologies as well as between different RNCs (lur) and so forth.

The proposed technology will now be described with reference to a number of non- limiting examples.

FIG. 3 is a schematic diagram illustrating an example of detection of neighbor cell relation(s) based on a call drop event and a corresponding call setup event in an inter-RNC scenario. 1 . UE 1 is connected to Cell A belonging to a base station such as a Node B 40-1 . The call is dropped.

2. The dropped call is registered in RNC1 , 50-1 . 3. RNC1 , 50-1 , determines/collects information related to the dropped call event, e.g. including UE identity such as IMSI, TMSI, P-TMSI or IMEI, an optional time stamp, last cell info, and so forth, and transmits the event information to an OSS/NMS node 120/130. The OSS/NMS node collects and stores the event information for a certain time.

4. UE1 establishes a connection to Cell B belonging to a base station such as a Node B 40-2. This cell is not defined as a neighbor cell to A in RNC1 .

5. RNC2, 50-2, registers the new connection of UE1 and determines/collects information related to the new connection event, e.g. including UE identity such as IMSI, TMSI, P-TMSI or IMEI, an optional time stamp, new cell info, and so forth. The event information is transmitted to OSS/NMS node 120/130. 6. An event hit is registered in OSS/NMS 120/130 when the UE identity for the dropped event matches the UE identity for the new connection event. 7. An Automatic Neighbor Relation, ANR, is identified and possibly created.

Cell B may then be registered as a neighbor cell to Cell A in RNC1 . The new relation may be verified and kept if found beneficial. In case it is not beneficial it can be removed at a later stage. In this example, two RNCs are shown. However, this solution is equally useful within and between any other radio access technology such as for example GSM, WCDMA, LTE and Wifi. The correlation could also be performed in an RNC, BSC and so forth for identification of missing relations within that node. In an optional embodiment, typical implementation is expected to be at OSS or NMS level in order to be able to identify relations between cells of any radio access technology.

As indicated in FIG. 3, the cells A and B may have different operating frequencies and thus represent an IEF relation, or they may have the same frequency and represent an IAF relation.

As understood by the skilled person, there are several options with respect to which UE identity to use. For WCDMA, it is possible to use a variety of different identities, such as IMSI, TMSI, P-TMSI or IMEI. IMSI is not available in the LTE NodeB and thus for this scenario OSS/NMS 120/130 might need to involve the core network and nodes such as the MME in order to resolve temporary identities.

FIG. 7 is a schematic signaling diagram illustrating an example of the correlation of a call drop event and a call establishment event in an inter-RNC scenario corresponding to that of FIG. 3.

As an example, the allowed time interval between call drop and new connection could be set generously. In most cases it is indeed valuable to get as many potential candidates as possible rather than trying to minimize detection of non- usable candidates. For example for IEF and IRAT, for which not many good alternative methods exist, it may be better to get too many candidates which can later on be evaluated and judged for usefulness rather than setting the time too short and miss some useful candidates. Alternatively, no time limitation is applied.

For example, with the use of URA_PCH in WCDMA, most UEs are expected to be kept in connected mode more or less continuously. This is especially true for smart phones. Thus the amount of new connection establishments or set-ups should be fairly equal to the amount of dropped calls and thus the correlation of events should be less of a challenge. However for LTE, with more frequent transitions between RRCJDLE and RRC_CONNECTED states, this method might be more challenging to implement from a load perspective, e.g. in the OSS and/or NMS.

A neighbor relation identified by this method should normally be regarded as a potential candidate. Even if the same neighbor relation would be identified for a larger number of UEs, there is still no guarantee that there is continuous coverage between cell A and cell B and that the relation will be useful for handover. Thus, after identification of a new neighbor relation it is usually beneficial to actually try the relation in real handovers in order to see if it is useful or not.

FIG. 4 is a schematic simplified diagram illustrating an example of detection of neighbor cell relation(s) in an intra-RNC scenario. In this particular example, one and the same RNC 50 may collect the required information related to connection drop events and connection establishment events, and correlate a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the collected information, and subsequently identify, based on cell information related to the correlated connection drop event and connection establishment event, one or more neighbor cell relation(s).

FIG. 5 is a schematic simplified diagram illustrating an example of detection of neighbor cell relation(s) between cells of different radio access technologies. In this particular example, cell A may belong to a base station 20 such as Base Station Transceiver, BTS, or Radio Base Station, RBS, of a G(E)RAN network such as GSM. A dropped call in cell A may be registered by the corresponding BSC 30, which determines/collects information related to the dropped call event and transmits the event information to the OSS/NMS node 120/130. The same UE then establishes a connection to Cell B belonging to a base station such as a Node B 40 of a UTRAN network such as WCDMA. The corresponding RNC 50 registers the new connection and determines/collects information related to the new connection event, and transmits the event information to the OSS/NMS node 120/130. The OSS/NMS node 120/130 thus ultimately collects the required event information. An event hit is registered in OSS/NMS 120/130 when the UE identity for the dropped event matches the UE identity for the new connection event, and an Automatic Neighbor Relation, ANR, is identified between cell A in G(E)RAN and cell B in UTRAN. It is also possible that a connection drop event may occur in UTRAN and be correlated to a connection establishment event in G(E)RAN.

FIG. 6 is a schematic simplified diagram illustrating another example of detection of neighbor cell relation(s) between cells of different radio access technologies. In this particular example, cell A may belong to a base station 40 such as a Node B in a UTRAN network such as WCDMA. A dropped call in cell A may be registered by the corresponding RNC 50, which determines/collects information related to the dropped call event and transmits the event information to the OSS/NMS node 120/130. The same UE then establishes a connection to Cell B belonging to a base station such as an eNB 60 of an E-UTRAN network such as LTE. The eNB 60 registers the new connection and determines/collects information related to the new connection event, and transmits the event information to the OSS/NMS node 120/130. The eNB may forward information, such as a temporary UE identity, enabling the identification of the UE to an MME 100, which may resolve the identity of the UE and send this information to the OSS/NMS. An event hit is registered in OSS/NMS 120/130 when the UE identity for the dropped event matches the UE identity for the new connection event, and an Automatic Neighbor Relation, ANR, is identified between cell A in UTRAN and cell B in E-UTRAN. It is also possible that a connection drop event may occur in E-UTRAN and be correlated to a connection establishment event in UTRAN. FIG. 8 is a schematic diagram illustrating an example of registered connection drop events and connection establishment events and the correlation of events for detecting possible neighbor cell relation(s). In this particular example, connection drop events are registered in a first table including information about the events such as UE ID and CELL ID, and optional further information. Similarly, connection establishment events are registered in a second table including information about the events such as UE ID and CELL ID, and optional further information. In this example, it can be seen that there is a match with respect to the UE identity, UE ID, related to connection drop event #3 and connection establishment event #2. Based on this match, the ANR functionality can identify a neighbor cell relation between cell Z and cell K as a candidate relation, using the cell information, CELL ID, of the corresponding registered events. This may be a one-way relation or a two-way relation, depending on the operation and/or configuration of the involved nodes.

It will be appreciated that the methods and devices described herein can be combined and re-arranged in a variety of ways.

For example, embodiments may be implemented in hardware, or in software for execution by suitable processing circuitry, or a combination thereof. The steps, functions, procedures, modules and/or blocks described herein may be implemented in hardware using any conventional technology, such as discrete circuit or integrated circuit technology, including both general-purpose electronic circuitry and application-specific circuitry. Particular examples include one or more suitably configured digital signal processors and other known electronic circuits, e.g. discrete logic gates interconnected to perform a specialized function, or Application Specific Integrated Circuits (ASICs). Alternatively, at least some of the steps, functions, procedures, modules and/or blocks described herein may be implemented in software such as a computer program for execution by suitable processing circuitry such as one or more processors or processing units.

Examples of processing circuitry includes, but is not limited to, one or more microprocessors, one or more Digital Signal Processors (DSPs), one or more Central Processing Units (CPUs), video acceleration hardware, and/or any suitable programmable logic circuitry such as one or more Field Programmable Gate Arrays (FPGAs), or one or more Programmable Logic Controllers (PLCs).

It should also be understood that it may be possible to re-use the general processing capabilities of any conventional system, network node, device or unit in which the proposed technology is implemented. It may also be possible to re-use existing software, e.g. by reprogramming of the existing software or by adding new software components.

The proposed technology provides an apparatus configured to detect a neighbor cell relation between cells in a communication environment including at least one cellular communication network. The apparatus is configured to collect information related to connection drop events, wherein the information, for each connection drop event, includes information about the identity of the wireless device involved in the connection drop and cell information about cell(s) to which the wireless device was connected at connection drop. The apparatus is also configured to collect information related to connection establishment events, wherein the information, for each connection establishment event, includes information about the identity of the wireless device involved in the connection establishment and cell information about cell(s) to which the wireless device connected at connection establishment. Further, the apparatus is configured to correlate a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the collected information related to connection drop events and connection establishment events. The apparatus is also configured to identify, based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment.

By way of example, the apparatus may be configured to evaluate the collected information related to connection drop events and connection establishment events by comparing, event-by-event, the information about the identity of the wireless device involved in a connection drop with the information about the identity of the wireless device involved in a connection establishment until a match is detected, thereby correlating a connection drop event and a connection establishment event relating to the same wireless device.

In an optional embodiment, the apparatus is configured to collect information, for each connection drop event, including a time stamp related to the connection drop event, and to collect information, for each connection establishment event, including a time stamp related to the connection establishment event. The apparatus may be configured to identify neighbor cell relation(s) based on cell information related to the correlated connection drop event and connection establishment event relating to the same wireless device is performed if the time stamp of the connection drop event and the time stamp of the connection establishment event are within a time interval.

In the particular example of FIG. 9, the apparatus 200 comprises a processor 210 and a memory 220. The memory 220 comprises instructions executable by the processor 210, whereby the apparatus/processor is operative to detect a neighbor cell relation. The term 'processor' should be interpreted in a general sense as any system or device capable of executing program code or computer program instructions to perform a particular processing, determining or computing task. The processing circuitry including one or more processors is thus configured to perform, when executing the computer program, well-defined processing tasks such as those described herein.

The processing circuitry does not have to be dedicated to only execute the above- described steps, functions, procedure and/or blocks, but may also execute other tasks.

Optionally, the apparatus 200 may also include a communication circuit 230. The communication circuit 230 may include functions for wired and/or wireless communication with other devices and/or network nodes in the network. In a particular example, the apparatus may include radio circuitry for communication with one or more other nodes, including transmitting and/or receiving information. The communication circuit 230 may be interconnected to the processor 210 and/or memory 220. As an example, the apparatus may be configured to detect a neighbor cell relation between cells in a WCDMA network.

By way of example, the apparatus may be part of a network node or management system in a communication network.

FIG. 10 is a schematic block diagram illustrating an example of a management system and/or a network node in a communication network comprising an apparatus of FIG. 9. For example, the management system is a network management system or an operation and support system. For example, the network node is a radio network controller, a base station controller or an evolved base station.

In a particular example, referring to the schematic example illustrated in FIG. 1 1 , at least some of the steps, functions, procedures, modules and/or blocks described herein are implemented in a computer program 425; 435 which is loaded into the memory 420 for execution by processing circuitry including one or more processors 410. The processor(s) 410 and memory 420 of this computer-implementation 400 are interconnected to each other to enable normal software execution. An optional input/output device may also be interconnected to the processor(s) and/or the memory to enable input and/or output of relevant data such as input parameter(s) and/or resulting output parameter(s).

FIG. 12 is a schematic computer flow diagram according to an embodiment.

In a particular embodiment, the computer program comprises instructions, which when executed by at least one processor, cause the processor(s) to:

S1 1 : read information related to connection drop events,

S12: read information related to connection establishment events,

wherein the information, for each connection establishment event, includes information about the identity of the wireless device involved in the connection establishment and cell information about cell(s) to which the wireless device connected at connection establishment;

S13: correlate a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the information related to connection drop events and connection establishment events; and

S14: identify, based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment. The proposed technology also provides a carrier comprising the computer program, wherein the carrier is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or a computer-readable storage medium. In particular, the proposed technology provides a computer program product comprising a computer-readable medium 420; 430 having stored thereon a computer program 425; 435 as described herein.

By way of example, the software or computer program may be realized as a computer program product, which is normally carried or stored on a computer-readable medium, in particular a non-volatile medium. The computer-readable medium may include one or more removable or non-removable memory devices including, but not limited to a Read-Only Memory (ROM), a Random Access Memory (RAM), a Compact Disc (CD), a Digital Versatile Disc (DVD), a Blu-ray disc, a Universal Serial Bus (USB) memory, a Hard Disk Drive (HDD) storage device, a flash memory, a magnetic tape, or any other conventional memory device. The computer program may thus be loaded into the operating memory of a computer or equivalent processing device for execution by the processing circuitry thereof.

The flow diagram or diagrams presented herein may therefore be regarded as a computer flow diagram or diagrams, when performed by one or more processors. A corresponding apparatus may be defined as a group of function modules, where each step performed by the processor corresponds to a function module. In this case, the function modules are implemented as a computer program running on the processor. Hence, the apparatus may alternatively be defined as a group of function modules, where the function modules are implemented as a computer program running on at least one processor.

The computer program residing in memory may thus be organized as appropriate function modules configured to perform, when executed by the processor, at least part of the steps and/or tasks described herein. An example of such function modules is illustrated in FIG. 13.

FIG. 13 is a schematic block diagram illustrating an example of an apparatus for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network. In this example, the apparatus 500 comprises:

a first collecting module 510 for collecting information related to connection drop events,

wherein the information, for each connection drop event, includes information about the identity of the wireless device involved in the connection drop and cell information about cell(s) to which the wireless device was connected at connection drop;

a second collecting module 520 for collecting information related to connection establishment events,

- a correlation module 530 for correlating a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the information related to connection drop events and connection establishment events; and

an identification module 540 for identifying, based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment. Alternatively it is possibly to realize the modules in FIG. 13 predominantly by hardware modules, or alternatively by hardware. The extent of software versus hardware is purely implementation selection. The embodiments described above are merely given as examples, and it should be understood that the proposed technology is not limited thereto. It will be understood by those skilled in the art that various modifications, combinations and changes may be made to the embodiments without departing from the present scope as defined by the appended claims. In particular, different part solutions in the different embodiments can be combined in other configurations, where technically possible.

Claims

1 . A method for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network, wherein the method comprises:

collecting (S1 ) information related to connection drop events, wherein the information, for each connection drop event, includes information about the identity of the wireless device involved in the connection drop and cell information about cell(s) to which the wireless device was connected at connection drop;

collecting (S2) information related to connection establishment events, wherein the information, for each connection establishment event, includes information about the identity of the wireless device involved in the connection establishment and cell information about cell(s) to which the wireless device connected at connection establishment;

correlating (S3) a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the collected information related to connection drop events and connection establishment events; and

- identifying (S4), based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment.

2. The method of claim 1 , wherein the collected information related to connection drop events and connection establishment events is evaluated by comparing, event-by-event, the information about the identity of the wireless device involved in a connection drop with the information about the identity of the wireless device involved in a connection establishment until a match is detected, thereby correlating a connection drop event and a connection establishment event relating to the same wireless device.

3. The method of claim 1 or 2, wherein the information, for each connection drop event, also includes a time stamp related to the connection drop event, and the information, for each connection establishment event, also includes a time stamp related to the connection establishment event, and

wherein the step (S4) of identifying neighbor cell relation(s) based on cell information related to the correlated connection drop event and connection establishment event relating to the same wireless device is performed if the time stamp of the connection drop event and the time stamp of the connection establishment event are within a time interval.

4. The method of any of the claims 1 to 3, wherein the cell information about cell(s) to which the wireless device was connected at connection drop includes information about cell(s) in the active set at connection drop, and the cell information about cell(s) to which the wireless device connected at connection establishment includes information about cell(s) in the active set at connection establishment.

5. The method of any of the claims 1 to 4, wherein the connection establishment events are triggered by call setups and/or connection-related registrations.

6. The method of any of the claims 1 to 5, wherein the identified neighbor cell relation(s) is/are regarded as candidate neighbor cell relation(s).

7. The method of any of the claims 1 to 6, wherein the method is performed for detecting a neighbor cell relation between cells in a WCDMA network.

8. The method of any of the claims 1 to 7, wherein the identified neighbor cell relation(s) is at least one of:

an intra-frequency relation,

- an inter-frequency relation,

an intra-radio access technology relation,

an inter-radio access technology relation,

an intra-base station relation, an inter-base station relation,

an intra-base station controller relation,

an inter-base station controller relation,

an intra-radio network controller relation,

- an inter-radio network controller relation,

an intra-operation and support system relation, and

an inter-operation and support system relation.

9. The method of any of the claims 1 to 8, wherein the method is performed by a network node (30; 50; 60) or management system (120; 130) in a communication network.

10. The method of claim 9, wherein the method is performed by a network management system (130), an operation and support system (120), a radio network controller (50), a base station controller (30) or an evolved base station (60).

1 1 . An apparatus (200; 400; 500) configured to detect a neighbor cell relation between cells in a communication environment including at least one cellular communication network,

wherein the apparatus (200; 400; 500) is configured to collect information related to connection drop events, wherein the information, for each connection drop event, includes information about the identity of the wireless device (10) involved in the connection drop and cell information about cell(s) to which the wireless device was connected at connection drop;

wherein the apparatus (200; 400; 500) is configured to collect information related to connection establishment events, wherein the information, for each connection establishment event, includes information about the identity of the wireless device (10) involved in the connection establishment and cell information about cell(s) to which the wireless device connected at connection establishment; wherein the apparatus (200; 400; 500) is configured to correlate a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the collected information related to connection drop events and connection establishment events; and

wherein the apparatus (200; 400; 500) is configured to identify, based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment.

12. The apparatus of claim 1 1 , wherein the apparatus (200; 400; 500) is configured to evaluate the collected information related to connection drop events and connection establishment events by comparing, event-by-event, the information about the identity of the wireless device involved in a connection drop with the information about the identity of the wireless device involved in a connection establishment until a match is detected, thereby correlating a connection drop event and a connection establishment event relating to the same wireless device.

13. The apparatus of claim 1 1 or 12, wherein the apparatus (200; 400; 500) is configured to collect information, for each connection drop event, including a time stamp related to the connection drop event, and to collect information, for each connection establishment event, including a time stamp related to the connection establishment event, and

wherein the apparatus (200; 400; 500) is configured to identify neighbor cell relation(s) based on cell information related to the correlated connection drop event and connection establishment event relating to the same wireless device is performed if the time stamp of the connection drop event and the time stamp of the connection establishment event are within a time interval.

14. The apparatus of any of the claims 1 1 to 13, wherein the apparatus (200; 400) comprises a processor (210; 410) and a memory (220; 420), said memory comprising instructions executable by the processor, whereby the processor is operative to detect a neighbor cell relation.

15. The apparatus of any of the claims 1 1 to 14, wherein the apparatus (200; 400; 500) is part of a network node (30; 50; 60; 300) or management system (120; 130; 300) in a communication network.

5 16. The apparatus of any of the claims 1 1 to 15, wherein the apparatus is configured to detect a neighbor cell relation between cells in a WCDMA network.

17. A management system (120; 130; 300) in a communication network, wherein the management system comprises an apparatus (200; 400; 500) of any of the

10 claims 1 1 to 16.

18. The management system of claim 17, wherein the management system (120; 130; 300) is a network management system (130), or an operation and support system (120).

15

19. A network node (30; 50; 60; 300) in a communication network, wherein the network node (30; 50; 60; 300) comprises an apparatus (200; 400; 500) of any of the claims 1 1 to 16.

20 20. The network node of claim 19, wherein the network node (30; 50; 60; 300) is a radio network controller (50), a base station controller (30) or an evolved base station (60).

21 . A computer program (425; 435) comprising instructions, which when executed 25 by at least one processor, cause the at least one processor to:

read information related to connection drop events,

wherein the information, for each connection drop event, includes information about the identity of a wireless device involved in the connection drop and cell information about cell(s) to which the wireless device was connected at connection 30 drop;

read information related to connection establishment events,

correlate a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the information related to connection drop events and connection establishment events; and

identify, based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment.

22. A computer program product comprising a computer-readable medium (420; 430) having stored thereon a computer program (425; 435) of claim 21 .

23. An apparatus (500) for detecting a neighbor cell relation between cells in a communication environment including at least one cellular communication network, wherein the apparatus (500) comprises:

a first collecting module (510) for collecting information related to connection drop events,

- a second collecting module (520) for collecting information related to connection establishment events,

a correlation module (530) for correlating a connection drop event and a connection establishment event relating to the same wireless device based on the information about the identity of the wireless device in the information related to connection drop events and connection establishment events; and

an identification module (540) for identifying, based on cell information related to the correlated connection drop event and connection establishment event, neighbor cell relation(s) between at least one of the cell(s) to which the wireless device was connected at connection drop and at least one of the cell(s) to which the wireless device connected at connection establishment.