WO2012052398A1

WO2012052398A1 - Reporting in communications systems

Info

Publication number: WO2012052398A1
Application number: PCT/EP2011/068106
Authority: WO
Inventors: Gyula Bodog; Yi Zhang
Original assignee: Nokia Siemens Networks Oy
Current assignee: Nokia Solutions and Networks Oy
Priority date: 2010-10-19
Filing date: 2011-10-17
Publication date: 2012-04-26
Anticipated expiration: 2013-04-19
Also published as: CN102457868A

Abstract

A method (200) of reporting an MDT log in a cellular mobile network, the method comprising the steps of: a base station (308) receiving an MDT log (332); the base station checking whether a TCE IP address is available for the MDT log and if it is determined that the address is not available sending (334) a request in respect of the address to a element manager (204); the element manager notifying (336) a managing entity (202) that the address is not available; and providing (338, 340) the address to the base station in order that the measurement log can be sent (344) to a TCE (214).

Description

REPORTING IN COMMUNICATIONS SYSTEMS

This invention relates to reporting in communications systems. It is particularly, but not exclusively, related to measurement reporting in mobile communications systems. It may apply to a cellular mobile communications system.

An important aspect in network planning to provide a wireless communications system is in ensuring that a network provides the necessary coverage. This may be to provide even coverage or to provide uneven coverage, for example better coverage being provided in areas in which there is the heaviest wireless communications traffic. Coverage in this sense usually refers to the signal strength experienced by a mobile terminal in a cell. It may also refer to the reliability of inter-cell handover.

Although there have been considerable improvements made in network planning over the past few years enabling a planned network to have the kind of coverage which is desired, the operation of a network implemented according to such a plan may not be exactly as intended. For this reason, mobile network operators employ a procedure referred to as drive testing in which vehicles equipped with special testing equipment travel around the area covered by a mobile network and collect measurement data at different geographical locations in the form of parameters such as signal strength. This means that a mobile network operator can identify problems such as coverage holes or places where handover tends to fail and change the configuration of the network to ameliorate these problems, for example by adding base stations, or changing beam orientation of existing base stations . Carrying out drive testing to obtain measurement data is expensive and inconvenient both in terms of the cost of the necessary equipment and of employees' or contractors' time. Therefore, it is desired to minimise the amount of drive testing which is conducted. It has been proposed in 3GPP (3rd Generation Partnership Project) to use subscriber mobile terminals (also referred to as user equipment or UE) to provide measurement data related to quality of connection over an air interface between themselves and a radio access network (RAN) of a mobile network and to use this data in a network management system of the network in order to reduce the need to carry out drive tests. Although this may not completely eliminate the need for drive testing, it is hoped that if the majority of coverage assessments can be carried out based on automatically collected measurement data obtained by the RAN in communicating with subscriber mobile terminals, there is scope for considerable cost savings. The capability to provide the necessary measurement data from subscriber mobile terminals to minimise the amount of drive testing required is referred to as minimisation of drive test (MDT) functionality.

It has been proposed to use trace functionality present within a network to gather the measurement data required for MDT. Trace functionality is able to carry out traces of two basic trace types:

i) a cell trace in which trace data is collected in one cell or a pre-defined list of cells; and

ii) a subscriber trace in which trace data is collected for a particular mobile terminal irrespective of which cell it has moved to . To use a cell trace to gather the measurement data required for MDT, also referred to as area-based MDT, a management entity sends an MDT request to carry out trace activation to a suitable element in the RAN such as a functionality controlling radio resource management of base station-type network elements. For the sake of simplicity, in the following, the term "base station" is intended to refer to base stations having incorporated into them functionality controlling radio resource management and also to refer to such functionality being a separate entity with respect to the base station-type network element it controls.

The management entity is typically present in an operations and maintenance (OAM) function, also referred to as a management system. The RAN element becomes configured for MDT and also activates selected mobile terminals which it is serving to carry out MDT measurements and to provide it with MDT measurement data. This involves applying a suitable MDT configuration to the mobile terminals. The RAN element provides MDT measurement data to the management entity, in particular a trace collection entity (TCE) present in the management system, which collects and processing them to produce results relating to geographical determination of coverage. Although area-based MDT has been described in relation to a single RAN element, it can also be carried out in relation to a number of RAN elements if, for example, the area to be measured extends over a number of cells.

It will be understood that a cell trace is transformed into a number of individual activation commands, each of which is received, and accepted, by relevant mobile terminals. In configuring base stations (and consequently mobile terminals) for area-based MDT, the management entity communicates directly with the RAN entity. Such communication does not involve the core network carrying out any related activities other than conveying necessary messages and information .

The design of modern telecommunication networks is based on Telecommunication Management Network (TMN) principles. TMN defines a set of interface points for network elements which perform communications processing to be accessed by elements, such as management elements, to monitor and control them. Accordingly, it defines a manager function for managing entities assigned to a lower level and an agent function for communicating with a higher level.

In order to monitor and control a telecommunications network, a manager initiates requests, which are executed by agent parts of managed entities. The manager receives corresponding responses. In order to ensure efficient network management, an agent part recognises relevant events within the network, generates notifications, and transmits these notifications as event reports to the manager.

A number of network-related activities, for example related to configuration, maintenance, and fault management, have been standardised within 3GPP as specific Integration Reference Points (IRPs) . An IRP is the means by which an IRPAgent (typically an element management (EM) entity or a network element (NE) entity) can communicate network management (NM) related information to one or several IRPManagers (NM entities) . Communications between IRPAgents in an EM layer and IRPManagers in an NM layer take place over an interface referred to as the Itf-N interface. The EM layer can be considered to be distributed having a number of separate distributed entities and the NM layer can be considered to be a centralised entity.

MDT commands are applied to NEs by use of a specific IRP referred to as Trace IRP. MDT reports are provided by use of a specific IRP referred to as File IRP. An MDT request indicates the type of reporting to be used and also the type of MDT configuration to be applied to mobile terminals. Currently, in 3GPP, two MDT reporting approaches are being considered. One is Immediate MDT reporting and another is Logged MDT reporting. In Immediate MDT reporting, a mobile terminal carries out specified measurements and provides periodic and event-based real-time MDT reports while there is a Radio Resource Control (RRC) connection available between it and the network. If there is no RRC connection, the mobile terminal stops measuring (and therefore stops reporting) only to resume when an RRC connection again becomes available. In Logged MDT reporting, a mobile terminal does not carry out MDT reporting while there is an RRC connection available between it and the network, but when there is no RRC connection available, it carries out specified measurements and generates MDT logs (also referred to as MDT reports) . These can then be sent to the network when an RRC connection is established or re-established. The mobile terminal does not carry out specified MDT measurements until the RRC connection is released.

To configure a mobile terminal for Logged MDT reporting, a suitable MDT configuration is applied to the mobile terminal when there is an RRC connection in place between it and a base station. In this RRC-connected mode, the mobile terminal is actively using a channel for control plane signalling between itself and the network. MDT data collection, that is measuring, is done by the mobile terminal when it is in idle mode. Idle mode refers to periods of time during which no dedicated resources, for example radio resources, are being used by the mobile terminal. In idle mode, the mobile terminal listens to channels which are concerned with obtaining network access, for example channels which provide parameters needed by the mobile terminal to identify the network and gain access to it and which broadcast paging and notification messages. During such time periods there is no RRC connection in place between the mobile terminal and the network .

A Logged MDT reporting configuration typically specifies parameters to be measured, frequencies of measuring and reporting, a period over which reporting is to be carried out, and a trace reference. It is known from standardisation activities that when the mobile terminal becomes RRC- connected again from idle mode, it will send an MDT log availability indication to the network to indicate the availability of a stored MDT log if it has an MDT log relevant to the radio access technology (RAT) type of the RRC connection. The log availability indication is sent in RRC signalling from the mobile station to the base station in a suitable RRC-related message. The base station can then decide whether to retrieve the data and, if so, the base station uses a suitable RRC signalling message, for example a UEInformationRequest message, to initiate the mobile terminal to upload the MDT log to the base station. In the case of area-based Logged MDT (to be carried out for a specified area) the base stations involved in the specified area are configured with the same trace parameters, including an Internet Protocol (IP) address for the TCE, a trace reference, and a list of cell identifiers (cell IDs) in respect of the cells of the area over which MDT measurements are to be made. The mobile terminal is also configured with the trace reference and the list of cell IDs. The mobile terminal generates MDT logs while it is in the specified area. It does this by checking the cell ID of the serving base station, comparing it with the MDT configured list of cell IDs, and if there is a match, carrying out the measurements. If the mobile terminal carries out this check and there is no match, then it has determined that it has moved out of the specified area, and it stops carrying out MDT measurements.

At some point, the mobile terminal decides that it has an MDT log ready for uploading. Once this happens, when the mobile terminal becomes RRC-connected, it sends the log availability indication to its serving base station and the base station can then decide whether to retrieve the data. If the data is to be retrieved, the base station initiates the mobile terminal to upload the MDT log, together with the trace reference, to the base station. This can be done whether or not the mobile terminal is in the specified area.

When a base station receives an MDT log, it checks the received trace reference against any trace references with which it has been configured. If the base station has a matching trace reference, then this base station is one of those in respect of which that particular MDT operation was to be carried out. In this case, the base station is able to use the trace reference to obtain from its MDT configuration the IP address of the TCE which is to receive the MDT log, and then send the MDT log to this TCE. However, if the mobile terminal is outside the specified area, when the base station which receives the MDT log checks the trace reference against any trace references with which it has been configured, the base station will be unable to find a match, and it will determine that it has received an MDT log for which it was not configured. Accordingly, the base station will not be able to retrieve an IP address of a TCE which is the destination for this MDT log. Therefore, the base station is unable to send the MDT log to the relevant TCE. This applies whether or not the base station has been configured to carry out a different area-based MDT or no area-based MDT at all.

One proposed solution is that when the mobile terminal is MDT configured, it is also provided with the IP address of the TCE and the mobile terminal is to include this address when it sends its MDT logs to base stations. Thus, the base station receiving an MDT log is able to determine the address to which the MDT is to be forwarded. However, such an approach has drawbacks. Configuring a mobile terminal with the IP address of an entity in an operator's domain (for example the TCE) could expose the entity to remote attacks such as flooding and hacking.

According to a first aspect of the invention there is provided a method of measurement reporting in a network, the method comprising the steps of:

a network element receiving a measurement log; checking whether a destination address is available for the measurement log;

if it is determined that the destination address is not available sending a request in respect of the destination address to a controlling entity which controls the network element ;

notifying a managing entity that the destination address is not available; and

providing the destination address to the network element in order that the measurement log can be sent to the destination address .

Preferably, the controlling entity is one of a number of distributed controlling entities. The controlling entity may be an entity in an element manager layer. It may be an element manager entity.

Preferably, the managing entity is an entity in a network manager layer. It may be a network manager entity. Preferably, the managing entity communicates with an agent entity associated with the network element. The managing entity may be able to instruct the agent entity. The controlling entity and the managing entity may communicate via IRPs . The controlling entity as an IRPAgent may send notifications to the managing entity as an IRPManager. Commands may be sent by the IRPManager to the IRPAgent.

The controlling entity and the managing entity may comprise an OAM function. The 0AM function may be separated into an element management layer and a network management layer. The OAM function may be provided with a measurement management entity for handling requests related to the generation of measurement logs. The measurement management entity may cooperate with units in network elements which receive measurement-related commands.

Preferably, the measurement log relates to measurements carried out as a result of a cell trace. It may relate to area-based measurements carried out for MDT . It may relate to logged MDT.

Preferably, a network element has been configured to handle the measurement log. Configuration of the network element may involve providing it with a reference for the measurement log. Configuration of the network element may involve providing it with a destination address for the measurement log corresponding to the reference.

Preferably, at least one mobile terminal has been configured to carry out measurements to generate the measurement log and to provide it to the network element. The mobile terminal may send a log availability indication to the network to indicate the availability of a measurement log when one is available.

Measurements may be taken by the mobile terminal in order to generate the measurement log when there is no active connection available between it and the network element. Measurement logs may be received by the network element when there is an active connection available between it and the mobile terminal.

In the event that the network element receives a measurement log for which it was not configured, the network element may arrange for the sending of a message containing a reference associated with the measurement log to the controlling entity to trigger a response including the destination address which relates to the measurement log.

The controlling entity on receiving the message may determine that there is a missing attribute. This may cause the controlling entity to send a missing attribute notification to the managing entity. This notification may be sent by an IRPAgent in an EM layer to an iRPManager in an NM layer. The missing attribute notification may operate like a request but take the form of, and be handled as, a notification. It may be used to indicate a lack of information triggering as a response a command to configure missing information to the network element.

Preferably, the network element temporarily stores the measurement log and associated reference while it is waiting to receive the destination address. In response to receiving the notification, the managing entity may refer to a database containing mapping between references and destination addresses, may locate the relevant destination address, and then may provide the destination address to the controlling entity. The managing entity may send a command to the controlling entity specifying that the network element is to be configured with the destination address. The controlling entity may send an instruction to the network element for it to be configured with the destination address. The configuration may include an association with the reference.

The instruction may trigger the network element to use the reference to identify a corresponding measurement log, to create a trace record containing the measurement log, and to send the trace record to the destination address. The network element may retain the reference and the destination address and an association between them.

The destination address may be an IP address. It may be the address of a trace collection entity.

The network may be a mobile communications network. It may comprise a core network and a radio access network having a plurality of base stations. It may comprise a management system controlling the radio access network and the core network. The management system may communicate directly with the radio access network in configuring the network and receiving from it the measurement log.

The network may be an LTE network. It may be a third generation network, such as a Universal Mobile Telecommunications System (UMTS) network. In such a network, the entity handling the MDT logs and communicating with an upper layer via an element manager entity is a functionality controlling radio resource management of base station-type network elements such as an RNC . According to a second aspect of the invention there is provided a network element, the network element being capable of:

receiving a measurement log;

checking whether a destination address is available for the measurement log;

if it is determined that the destination address is not available sending a request in respect of the destination address to a controlling entity which controls the network element in order that a notification that the destination address is not available can be sent to a managing entity so that the network element can be provided with the destination address; and

sending the measurement log to the destination address.

Preferably, the network element is a base station. The network element may be a functionality controlling radio resource management of base station-type network elements.

According to a third aspect of the invention there is provided a communication network comprising a network element, a controlling entity, and a managing entity, wherein the network element is capable of:

receiving a measurement log;

checking whether a destination address is available for the measurement log; and

if it is determined that the destination address is not available sending a request in respect of the destination address to a controlling entity which controls the network element,

wherein the controlling entity is capable of notifying the managing entity that the destination address is not available; and

wherein the managing entity is capable of providing the destination address to the network element in order that the measurement log can be sent to the destination address.

According to a fourth aspect of the invention there is provided a computer program product comprising software code that when executed on a computing system performs a method of measurement reporting in a network, the method comprising the steps of: a network element receiving a measurement log;

checking whether a destination address is available for the measurement log;

notifying a managing entity that the destination address is not available; and

Preferably, the computer program product has executable code portions which are capable of carrying out the steps of the method .

Preferably, the computer program product is stored on a computer-readable medium. It may be stored in a non-transient way.

According to the invention, it is not necessary to configure a distributed set of entities such as network elements with all possible items of information which may be required and instead individual items of information can be obtained from a centralised entity when required.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a system according to the invention;

Figure 2 shows a trace activation and subsequent reporting being carried out in a network; and Figure 3 shows MDT measurement reporting and trace session reporting .

The invention will now be described in relation to Figure 1. Figure 1 shows an LTE mobile communications network 100 comprising a RAN 102 and a core network 104. The RAN has a number of base stations 106, 108, and 110 which provide radio access to mobile terminals 112, 114, and 116 present in cells 106', 108', and 110', and the core network 104 has functionality to provide for call switching/routing and call control, service provision, authentication and charging, and interconnection enabling access to other networks. In this embodiment, the base stations are eNBs . In addition, an operations, administration, and maintenance (OAM) function 118 is linked to the core network 104 and to the RAN 102 and is capable of configuring and provisioning network nodes of the RAN 102 and the core network 104. Such aspects of control are shown in Figure 1 by dashed lines between the OAM function 118 and the RAN 102 and the core network 104.

Although in Figure 1 the OAM function 118 is shown as a unitary entity, in reality, it is divided into an element management (EM) layer and a network management (NM) layer. The EM layer can be considered to be a distributed entity and the NM can be considered to be a centralised entity.

The EM layer and the NM layer communicate over the Itf-N interface separating them by means of IRPs, as discussed in the foregoing. In this case, an IRPAgent associated with an NE is able to send notifications to an IRPManager present in the NM layer, for example relating to the operation of the NE, and the IRPManager is able to send commands to IRPAgents in order to control the operation of NEs. The IRPAgent may be part of an NE such as an eNB or may be an EM entity. The OAM function 118 carries out various related tasks such as collecting network statistics, alarm monitoring and logging of events. The resulting statistics, alarms, and logs are used by a network operator to monitor the health and performance of the network 100. The OAM function 118 is a separate system from the core network 104 although both the core network 104 and the OAM function 118 are present within the domain of the network operator and both are under its control . The OAM function 118 is provided with an MDT management entity 120. This entity 120 controls MDT operation within the network 100, for example receiving instructions to arrange for MDT measurements to be gathered in respect of a particular subscriber or a specific geographic area of the network 100 and then sending out a necessary MDT request so that a base station or base stations can activate MDT measuring by a particular mobile terminal or by mobile terminals present in a particular location or locations. The MDT management entity 120 in the OAM function 118 cooperates with MDT units 122 in the base stations which receive MDT- related commands and take appropriate action. For example, an MDT unit 122 in a particular base station receives a command that MDT measurements are to be carried out in a particular cell and, as a result, it applies individual MDT configurations to suitable mobile terminals located in the cell which cause the mobile terminals to start making MDT measurements and to provide MDT reports to the base station. The base station sends the MDT measurements in the form they are received or collates or otherwise processes them, and then sends them to the OAM function 118 where they may be processed and used to generate output data suitable for use in managing the network 100.

It should be understood that Figure 1 is highly schematic and is simplified. In reality, there may be RANs of different RAT types extending over a common area with mobile terminals being able to connect to both. For example, there may be both a third generation UMTS RAT type and an LTE RAT type. Each RAT type is able to send MDT requests so that mobile terminals carry out MDT measurements in respect of that particular RAT type. Since MDT-related interactions between the mobile terminals and a RAN occur when there is an RRC connection, a network of a particular RAT type carries out MDT-related operations in ignorance of MDT-related operations being carried out in a network of another RAT type.

As discussed in the foregoing, a base station may have applied an MDT configuration to a mobile terminal for area- based MDT. Once the mobile terminal has generated an MDT log, when it becomes RRC-connected, it indicates that it has an available MDT log and the base station is able to retrieve the MDT log. The mobile terminal sends the MDT log to the base station using an RRC message referred to as UEINformationRepsonse . This is a name which has provisionally been given to this operation although a different name may ultimately be used. The mobile terminal sends the trace reference with which it was configured for MDT together with the MDT log in the UEINformationRepsonse message.

According to the invention, when the base station receives the MDT log together with the trace reference, and the base station does not have a TCE IP address corresponding to that trace reference, the base station arranges for the sending of a notification message containing the trace reference to the management entity 120. This triggers a response including the IP address of the TCE relating to the trace reference. In particular, the notification message is sent by an IRPAgent of the base station to all possible IRPManagers present in the management entity 120 with which the IRPAgent has a connection. In this way, the notification message is sent from an EM entity to an NM entity.

When the IRPManager responsible for the particular trace reference receives the notification message, it is able to recognise that it is of a type requiring the IRPManager to obtain any TCE IP addresses associated with that trace reference and to return this address information to the IRPAgent. The IRPAgent provides the TCE address to the base station, and thus the base station is now able to forward the MDT log to the relevant TCE based on the information it has received from the management entity 120.

In one embodiment of the invention, the notification message only needs to contain the trace reference because, from the perspective of the IRPManager, both its origin (and thus the recipient of any response) , and what action is required due to the message type, are implicit in the message.

Figure 2 shows a trace activation and subsequent reporting 200 being carried out in a network according to the invention. The network comprises a network management entity (NM) 202, an element manager (EM) 204, a mobility management entity (MME) 206, a base station (eNB) 208 associated with the EM 204, a first mobile terminal UE1 210, a second mobile terminal UEn 212, and a TCE 214. The TCE 214 is in the NM layer of the system. It will be understood that the network comprises a number of base stations although all are not shown. However, an additional base station, eNB 308, is shown and described in Figure 3.

Returning back to Figure 2, initially, the NM 202 is instructed to carry out an area-based Logged MDT procedure. The NM 202 sends an ActivateTraceJob message 216 to the EM 204. The EM 204 sends a Trace Session Activation message 218 to a relevant base station (in this case the eNB 208) . This message 218 includes a configuration to be applied to a mobile terminal to cause it to carry out MDT measurements, that is a UE measurement configuration 220.

The eNB 208 starts the requested trace session and configures itself correspondingly 222. It does this by saving relevant trace parameters including a trace reference relating particularly to the requested trace. The eNB 208 then activates a trace 224 in respect of the first mobile terminal UE1 210 and then activates a trace 226 in respect of the second mobile terminal UEn 212. As a result, the first and second mobile terminals, UEl 210 and UEn 212, are configured for area-based Logged MDT and each has stored the trace reference. Accordingly, they are set up to carry out MDT measurements and to report these measurements in MDT logs to the eNB 208 when they are in RRC-connected mode.

The mobile terminal UEn is configured in carry out MDT measurement in respect of the cell of eNB 208 while it is in idle mode. Once it has carried out sufficient MDT measurements to have an MDT log to send, when it becomes RRC- connected in the cell of eNB 208 it provides the MDT log in a message 228. The message 228 also includes the trace reference. In Figure 2, the message 228 is being used as shorthand to represent a number of steps, in particular an indication being sent to the eNB 208 that there is an MDT log available to be uploaded, a confirmation being sent to the mobile terminal that the MDT log is to be uploaded, and uploading of the MDT log.

The eNB 208 checks its configuration, identifies the TCE IP address associated with the trace reference, and then creates a Trace Record containing the corresponding MDT log, which is given the TCE IP address and then reported 230 to the TCE 214. Once this has been done the eNB 208 discards the MDT log .

Figure 3 shows MDT measurement reporting and trace session reporting to the TCE 214 according to the invention. It should be noted that this is happening in the same network as Figure 2 although one network element participating in the exchange of messages, the eNB 308, is not the same network element as the eNB 208. As has been described in the foregoing, in the case of area-based MDT, mobile terminals may move out of a cell in respect of which they are to carry out MDT measurements. This has happened in the case of Figure 3. The mobile terminal UE1 is configured to carry out area- based Logged MDT measurement in respect of the cell of eNB 208 but, having carried out sufficient MDT measurements while it was in idle mode to have an MDT log to send, it now becomes RRC-connected in the cell of the eNB 308 and provides the MDT log and the trace reference in a message 332. In one embodiment of the invention, the message 332 is a UEInformationResponse message. The message 332, in common with the message 228, is a shorthand representation of an indication step, a confirmation step, and an uploading step.

The eNB 308 receives the message 332 and is able to determine from the trace reference in the message that the trace relates to an MDT trace for which the eNB 308 has not been configured. As a result, the eNB 308 temporarily stores the trace reference and associated MDT log and sends a message 334 to the EM 204 requesting that the TCE IP address be provided to the eNB 308. The message 334 includes the trace reference .

On receiving the message 334, the EM 204 recognises it as a message indicating that there is a missing attribute. Consequently, the EM 204 sends a missing attribute notification 336 to the NM 202 (also including the trace reference) . This message is sent by an IRPAgent in the EM layer to an IRPManager in the NM layer. The NM 202 receives this notification 336 and recognises that it is to provide a TCE IP address corresponding to the trace reference. Accordingly, it refers to a database containing mapping between trace references and TCE IP addresses, locates the relevant TCE IP address, and then sends a message 338 to the EM 204 in order to provide the TCE IP address to the eNB 308.

In this embodiment of the invention, the message 338 comprises a "set" command and includes the trace reference and the TCE IP address. This command is an instruction for an eNB to configure a missing attribute, in particular to configure the eNB with the TCE IP address associated with the trace reference. The EM 204 then sends a message 340 to the eNB 308 in order to provide the TCE IP address to the eNB 308. In this embodiment of the invention, the message 340 comprises a "set" command corresponding to the "set" command in the message 338 and includes the trace reference and the TCE IP address. The eNB 308 receives the message 340, uses the trace reference in the message 340 to identify the relevant MDT log, and then creates a Trace Record 342 containing the MDT log appended with the TCE IP address which is then sent 344 to the TCE 214. Once this has been done the eNB 308 discards the MDT log. It may retain the trace reference and the TCE IP address. These may be discarded once the mobile terminal with which they are associated is no longer RRC-connected or once all relevant MDT logs have been retrieved.

It will be understood that the missing attribute notification 336 operates like a request or a command since the recipient of the notification carries out an action to deal with it and provides a response. However, in an agent-manager relationship present between the EM layer and the NM layer, it is not permitted for an EM element to command an NM element to carry out a task. Therefore, a notification is used to indicate a lack of information and the response is a command to configure the relevant NE with the missing information.

Although in the foregoing example, the invention is described as being implemented in an LTE system and the network elements are eNBs, the invention may be applied to other systems, including in a third generation system such as a UMTS system. In this case, the relevant entity carrying out the steps of the invention such as receiving the MDT log, checking whether a TCE IP address is available for the measurement log, sending a request for the TCE IP address to an EM entity, and sending the MDT log to the TCE may be a radio network controller (RNC) .

While preferred embodiments of the invention have been shown and described, it will be understood that such embodiments are described by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the scope of the present invention. Accordingly, it is intended that the following claims cover all such variations or equivalents as fall within the spirit and the scope of the invention.

Claims

1. A method of measurement reporting in a network, the method comprising the steps of:

a network element receiving a measurement log;

checking whether a destination address is available for the measurement log;

notifying a managing entity that the destination address is not available; and

2. A method according to claim 1 in which an 0AM function separated into an element management layer and a network management layer comprises the controlling entity and the managing entity.

3. A method according to claim 1 or claim 2 in which the controlling entity as an IRPAgent sends notifications to the managing entity as an IRPManager and commands are sent by the IRPManager to the IRPAgent.

4. A method according to any preceding claim in which in the event that the network element receives a measurement log for which it was not configured, the network element arranges for the sending of a message containing a reference associated with the measurement log to the controlling entity to trigger a response including the destination address which relates to the measurement log.

5. A method according to any preceding claim in which the controlling entity determines that there is a missing attribute and sends a missing attribute notification to the managing entity.

6. A method according to claim 5 in which the missing attribute notification takes the form of a notification but it operates to trigger as a response a command to configure missing information to the network element.

7. A method according to any preceding claim in which the managing entity refers to a database containing mapping between references and destination addresses, locates a relevant destination address, and then provides the destination address to the controlling entity.

8. A method according to any preceding claim in which the managing entity sends a command to the controlling entity specifying that the network element is to be configured with the destination address.

9. A method according to any preceding claim in which the controlling entity sends an instruction to the network element for it to be configured with the destination address.

10. A method according to claim 8 in which the configuration of the network element includes an association between a reference related to the measurement log and the destination address .

11. A method according to any preceding claim in which the destination address is an IP address of a trace collection entity .

12. A method according to any preceding claim in which the measurement log relates to measurements carried out for area- based logged MDT .

13. A network element, the network element being capable of: receiving a measurement log;

checking whether a destination address is available for the measurement log;

sending the measurement log to the destination address.

14. A communication network comprising a network element, a controlling entity, and a managing entity, wherein the network element is capable of:

receiving a measurement log;

if it is determined that the destination address is not available sending a request in respect of the destination address to a controlling entity which controls the network element, wherein the controlling entity is capable of notifying the managing entity that the destination address is not available; and

15. A computer program product comprising software code that when executed on a computing system performs a method of measurement reporting in a network, the method comprising the steps of:

a network element receiving a measurement log;

checking whether a destination address is available for the measurement log;

notifying a managing entity that the destination address is not available; and