WO2014023362A1

WO2014023362A1 - Enhanced measurement report trigger events using mobility information for heterogeneous networks

Info

Publication number: WO2014023362A1
Application number: PCT/EP2012/065763
Authority: WO
Inventors: Mikko Saily; Per Henrik Michaelsen; Simone BARBERA; Klaus Ingemann Pedersen; Lars Dalsgaard
Original assignee: Nokia Siemens Networks Oy
Priority date: 2012-08-10
Filing date: 2012-08-10
Publication date: 2014-02-13
Also published as: EP2883379A1

Abstract

Embodiments of the present invention provide an apparatus and a method by which measurements are carried out and measurement reports are sent on fulfillment of measurement trigger conditions related to measurement trigger parameters, the measurements and corresponding measurement reports being defined according to predefined measurement events, wherein for each measurement event a measurement trigger parameter is independently configured from other measurement trigger parameters for other measurement events. Furthermore, an apparatus and a method are provided by which a user equipment is configured to carry out the above functions.

Description

Enhanced Measurement Report Trigger Events using Mobility Information for Heterogeneous Networks

Field of the Invention

The present invention relates to apparatuses, methods and a computer program product for achieving enhanced measurement report trigger events using mobility information for heterogeneous networks.

Related background Art The following meanings for the abbreviations used in this specification apply:

3GPP 3rd Generation Partnership Project

CEM Customer Experience Management

E-UTRAN Evolved-Universal Terrestrial Radio Access Network

LTE Long Term Evolution

LTE-A Long Term Evolution-Advanced

MSE Mobility State Estimation

PCell Primary Cell

RAT Radio Access Technology

SIB System Information Block

SON Self-Organising Network

RRC Radio Resource Control

1 1 1 Time To Trigger

UE User Equipment (same as terminal)

Embodiments of the present invention relates to enhancement of measurement reporting trigger events and handovers in multi-layer cellular network, where users are moving at different velocities. Multilayer networks are also referred to as Heterogeneous Networks (HetNet). In this context, multi-layer refers to cases with a mixture of macro base stations and low power base stations (e.g. pico and micro). Multi-layer LTE network is used as an example for describing the method, although the idea could be applied to other cellular standards as well. Macro-layer and pico/micro layer may even be implemented in different RAT (for example HSPA macro layer and LTE micro layer). Measurement configuration defines how UE will experience its environment. A measurement report event defines the criteria to trigger a measurement report from user equipment towards the serving base station. Measurement report acts as an input to network mobility management in connected mode, while idle mode mobility is done autonomously by UE. Measurement report trigger events are specified in 3GPP TS36.331, section 5.5.4, "Measurement report triggering", and triggers are labelled as Am, where m = 1...6 for intra-RAT and Bn, where n = 1...2 for inter- RAT mobility.

3GPP TDoc R2-115420 ["Mobility robustness for fast moving UEs in HetNet", Nokia Siemens Networks, Nokia Corporation] shows an evaluated co-channel scenario where mobility problems of non-stationary users are associated with out-bound handovers from a low power cell, e.g. handout from pico cell to another pico or macro layer.

In particular, the measurement configurations are such that in heterogeneous networks there might be some situations in which the measurements cannot be carried out in a suitable manner.

Summary of the Invention Embodiments of the present invention address this situation and aim to provide a measurement configuration taking into account situations such as in a heterogenous network. Accord ing to a first aspect of the present invention an apparatus is provided which comprises

an interface unit configured to provide connection to a network, and

a processor configured

to carry out measurements and to send measurement reports on fulfillment of measurement trigger conditions related to measurement trigger parameters via the interface unit, the measurements and corresponding measurement reports being defined according to predefined measurement events,

wherein for at least one measurement event at least one measurement trigger parameter is independently configured from other measurement trigger parameters for other measurement events.

According to a second aspect of the present invention an apparatus is provided which comprises

an interface unit configured to provide connection to a network, and

a processor configured

to configure a user equipment to carry out measurements and to send measu rement reports on fu lfil l ment of measu rement trig ger conditions related to measurement trigger parameters, the measurements and corresponding measurement reports being defined according to predefined measurement events,

wherein for at least one measurement event at least one measurement trigger parameter is independently configured from other measurement trigger parameters for other measurement events. According to a third aspect of the present invention a method is provided which comprises

carrying out measurements and

sending measurement reports on fulfillment of measurement trig ger cond itions related to measu rement trigger para meters, the measurements and corresponding measurement reports being defined according to predefined measurement events,

According to a fourth aspect of the present invention a method is provided which comprises

configuring a user equipment to carry out measurements and to send measu rement reports on fu lfil l ment of measu rement trig ger conditions related to measurement trigger parameters, the measurements and corresponding measurement reports being defined according to predefined measurement events,

Advantageous modifications are defined in the dependent claims. According to a fifth aspect of the present invention a computer program product is provided which comprises code means for performing a method according to any one of the above third and fourth aspects and their modifications when run on a processing means or module. Thus, accord in g to embod i ments of the present i nvention , certai n measurement trigger conditions are defined independently for each measurement type. That is, for example, a measurement trigger condition such as a timeToTrigger (TTT) parameter can be individually configured for each measurement event.

Brief Description of the Drawings

These and other objects, features, details and advantages will become more fully apparent from the following detailed description of embodiments of the present invention which is to be taken in conjunction with the appended drawings, in which :

Fig . 1 shows a basic structure of a UE according to an embodiment of the present invention, and

Fig . 2 shows a basic operation of an eNB according to an embodiment of the present invention.

Detailed Description of embodiments In the following, description will be made to embodiments of the present invention. It is to be understood, however, that the description is given by way of example only, and that the described embodiments are by no means to be understood as limiting the present invention thereto. However, before explaining embodiments, the problem underlying the present application and considerations for the solution thereof are described in the following in more detail.

Namely, according to embodiments of the present invention the time is considered how long a trigger event entering condition must be valid, wherein according to the current definitions, the timer of event trigger, timeToTrigger (TTT), is not configurable per trigger event. According to 3GPP Rel-10 TS36.331 the time on how long the condition must be valid cannot be configured per event. This poses a problem where implicit combination of A3 and A5 cannot be operated nor configured in an optimum way due to a single possible TIT value. For example, it is not possible to configure A3 trigger event with an average TIT to achieve a balance between radio link failures and ping-pong handovers, and at the same time configuring A5 with a very short TTT to trigger "an escape" handover (i.e., a quick handover) immediately after a particular UE is in problematic radio conditions. Another problem relates to Mobility State Estimation ( MSE) [3G PP TS 36.304, TS 36.331], where the speed dependent parameters define the scaling of timeToTrigger (TTT) by three levels of MSE (normal, medium, high), each having a defined scaling factor defined in VarMeasConfig. [defined in 3GPP TS 36.331] .

The measurement configuration has some flexibility for fast moving UEs, but when MSE scales down the TTT parameter, it is done for all configured events based on SpeedStateScaleFactors. It should be also noted when leaving a small cell, the system (configured with typical pedestrian user parameters) cannot react quickly enough to handout a fast moving user successfully (as described in R2-115420 mentioned above). Therefore it would be useful to configure some events with short fixed TTT, e.g . without MSE based TTT scaling . Shortening TTT too much results excessive ping-pong handovers. However, according to Rel-10 specifications it is not possible and if MSE is configured, then it shall be used for all the events.

Yet another problem relates to the serving or target cell size or type. It would be useful to be able to scale each trigger event independently per event based on the source/target cell type. According to Rel-10 specifications this is not possible. In idle mode the cell reselection trigger event is controlled with two broadcasted parameters, t-Reselection and Qhyst [3GPP TS 36.304] . When UE is camping in a cell, these parameters are the same during the measurements using different mobility trigger events, regardless of the target cel l type while measuring . Therefore the same problem with trigger events and mobility states applies also for idle mode.

The UE variable VarMeasConfig [defined in 3GPP TS 36.331, section 7.1., see also section 5.5.6.2] includes the accumulated configuration of the measurements to be performed by the UE, covering intra-frequency, inter-frequency and inter-RAT mobility related measurements.

VarMeasConfig UE variable [TS 36.331]

AS Nl START

VarMeasConfig : : = SEQUENCE {

-- Measurement identities

measIdList MeasIdToAddModList OPTIONAL,

-- Measurement objects

measObjectList MeasObjectToAdd Mod List OPTIONAL, -- Reporting configurations

reportConfigList ReportConfigToAddModList OPTIONAL, -- Other parameters

quantityConfig QuantityConfig OPTIONAL, s-Measure RSRP-Range OPTIONAL, speedStatePars CHOICE {

release NULL,

setup SEQUENCE {

m o b i I ity Sta te Pa ra m ete rs MobilityStateParameters, timeToTrigger-SF SpeedStateScaleFactors }

} OPTIONAL

}

ASN1STOP

As can be seen from the above definition, the timeToTrigger- SF/SpeedStateScaleFactors are defined globally.

Moreover, the ReportConfigEUTRA specifies criteria for triggering of an E- UTRAN measurement reporting event. ReportConfigEUTRA information element [TS 36.331]

AS Nl START

ReportConfigEUTRA : : = SEQUENCE {

triggerType CHOICE {

event SEQUENCE {

eventld CHOICE {

eventAl SEQUENCE { al-Threshold ThresholdEUTRA

},

eventA2 SEQUENCE { a2-Threshold ThresholdEUTRA

},

eventA3 SEQUENCE { a3-Offset INTEGER (-30. 30), reportOnLeave BOOLEAN

},

eventA4 SEQUENCE { a4-Threshold ThresholdEUTRA

},

eventA5 SEQUENCE { a5-Threshold l ThresholdEUTRA, a5-Threshold2 ThresholdEUTRA

},

eventA6 SEQUENCE { a6-Offset INTEGER (-30. 30), a6- ReportOnLeave BOOLEAN

}

},

hysteresis Hysteresis,

timeToTrigger TimeToTrigger

},

periodical SEQUENCE {

purpose ENUMERATED { reportStrongestCells, reportCGI}

}

Also from the above definition it is derivable that the timeToTrigger is defined globally. E-UTRAN provides the measurement configuration applicable for a UE in RRC_CONNECTED by means of dedicated signalling, i.e. using the

RRCConnectionReconfiguration message. I n the fol l owi n g , the d isad va ntag es d ue to a g l oba l d efi n iti on of measurement trigger conditions such as timeToTrigger or SpeedStateScaleFactors are summerized :

1. UEs connected to small cells at high velocity are opposite to what is considered beneficial in order to improve mobility robustness, namely by keeping fast moving UEs out of small cells.

2. Considering an intra-frequency case, when UE performs measurements towards neighbouring cells, only one TimeToTrigger value is effectively used regardless of the event criteria.

3. Only one TimeToTrigger for all events doesn't allow combination of triggers where one trigger event (e.g . A3) would have a long TTT value and another trigger event (e.g . A5) would have a short TTT value with low power threshold val ue ind icating sig nal level above a rad io l in k failure.

This sets a big limitation in HetNet, where it would be useful to configure different events with different time periods on how long the entering condition must be valid before a measurement report can be triggered to indicate a need for handover, or UE to perform cell reselection in idle mode.

4. All trigger events will experience the same MSE down-scaling of TTT parameter. Therefore measurements are limited and not providing flexibility towards different cell types in various heterogeneous network deployments. 5. Mobility State Estimation will scale down the TIT value of each trigger event in RRC connected mode by factors [0.25, 0.50, 0.75, 1.00] . It is not possible to disable, change neither optimize the scaling factors per event. This can make the fast moving UEs to enter low power cells even faster when the trigger event contains value that is optimised for average user mobility profile.

6. Non-stationary, irregular and/or unpredictable trajectory of users can increase the need for diverse measurement configurations. For example SON (Self-Organizing Networks) and CEM (Customer Experience Management) are currently having challenges in differentiating the user performance due to limitations in defining the UE specific measurement parameters. Thus, based on the considerations given above, accord ing to certain embodiments flexibility for the UE measurements is achieved, namely by individually defining measurement trigger parameters (for example, such as timeToTrigger) individually for each measurement event. Fig . 1 shows a U E 1 as a n exam ple for a correspond ing a ppa ratus according to a more general embodiment of the present invention. The apparatus may be a UE or may be only a part thereof, for example. The UE 1 comprises a processor 11 and an interface unit 12. The interface unit 12 is configured to provide connection to a network, and the processor 11 is configured to carry out measu rements a nd to send measurement reports on fulfillment of measurement trigger conditions related to measurement trigger parameters via the interface unit, the measurements and corresponding measurement reports being defined according to predefined measurement events, wherein for each measurement event a measurement trigger parameter is independently configured from other measurement trigger parameters for other measurement events. Fig . 2 shows a eNB 2 as an example for a corresponding apparatus according to a more general embodiment of the present invention. This apparatus may be a eNB, a base station or another suitable network control element, or may be only a part thereof, for example. The UE 2 comprises a processor 21 and an interface unit 22. The interface unit 22 is configured to provide connection to a network, and the processor 21 is configured to configure a user equipment to carry out measurements and to send measurement reports on fulfillment of measurement trigger conditions related to measurement trigger parameters via the interface unit, the measurements and corresponding measurement reports being defined according to predefined measurement events, wherein for each measurement event a measurement trigger parameter is independently configured from other measurement trigger parameters for other measurement events.

Optionally, the UE 1 and the eNB 2 each may also comprise a memory 13 or 23 for storing data and programs, by means of which the processor 11 or 21 may carry out its corresponding functions. Thus, by defining individual measurement trigger parameters for each measurement event, UE measurements can be optimized with independent trigger timers, optionally using also the available user mobility information (MSE, X2 based UE History Information, ...) and cell specific size/type information in measurement trigger event configuration and optimization.

Thus, embodiments of the present invention can provide flexibility to the configuration of measurement trigger events for advanced mobility scenarios especially in areas where heterogeneous networks are deployed, and users are moving with different velocities.

Specifically, embodiments of the present invention provide an enhanced measurement configuration with the following elements: The enhanced measurement configuration allows definition of independent measurement trigger event values (e.g . TimeToTrigger) for different trigger events.

Moreover, the enhanced measurement configuration can include dedicated speed dependent scaling factors (e.g . SpeedStateScaleFactors) for one or more trigger events. Speed dependent scaling factors can be also used to indicate which trigger events are not evaluated using parameters that are scaled based on the mobility information or mobility state estimation related scaling .

The enhanced measurement configuration allows each trigger event to be configured to trigger only for a certain cell type, e.g . trigger for small cells based on the physical cell ID, for example.

In the following, implementation examples according to some embodiments of the present invention are described .

Implementation has several options considering that UE needs to receive independent timeToTrigger values for configured (or each) measurement report event(s).

One example of implementation could consider the following approach where timeToTrigger is added to each event, or it could be a list of TimeToTrigger values signalled to UE.

MSE scaling can be configured per event, where each event will have its scaling values in the format of SpeedStateScaleFactors, e.g . al- timeToTrigger-SF (SF = scale factors) . Sca le factors can a lso have al l values set to "1.0" meaning that scaling is not effective, e.g . MSE can be disabled for a certain event. Alternatively it could be indicated for which events the UE shall not apply MSE scaled parameters when doing event evaluation. In the following, an example for a modified definition of the ReportConfigEUTRA information element is given.

ReportConfigEUTRA : : = SEQUENCE {

triggerType CHOICE {

event SEQUENCE {

eventld CHOICE {

eventAl SEQUENCE { al-Threshold ThresholdEUTRA al-timeToTrigge TimeToTrigger al-timeToTrigge SpeedStateScaleFactors

},

(OTHER EVENTS REMOVED FROM THIS EXAMPLE) }

},

hysteresis Hysteresis,

timeToTrigger TimeToTrigger

(or list of EVENT specific TTTs)

},

periodical SEQUENCE {

purpose ENUMERATED { reportStrongestCells, reported}

}

},

As can be seen, with al-timeToTrigger, an event specific TTT (in this example for event Al) is provided, and with al-timeToTrigger-SF, event specific MSE scaling is provided . Furthermore, it is also indicated where a list of event specific TTTs could be provided within the definition.

Referring again back to the problem described above, for example in current 3GPP Rel-10 standard specification the implicit combination of A3 (Neighbour becomes offset better than PCell) and A5 (PCell becomes worse than absol ute threshold l and Neighbour becomes better than another absolute threshold2) doesn't work in an optimum way because the specification doesn't allow different TTTs for different events. Therefore in the intra-freq uency sma l l cel l deployment the "escape function" of A5 would be slow, when at the same time the A3 needs to have a longer value to avoid ping-pong handovers, for example.

Enhanced measurement configuration can be used in connected and idle mode and therefore the independent trigger event parameters can comprise of, but are not limited to : o timeToTrigger (connected mode)

o t-Reselection (idle mode)

In idle mode the reselection evaluation specific parameters can be signalled to UE using the broadcasted System Information Blocks (SIBs).

The embodiments described above and the solution to the problem are also applicable to enhance idle mode measurement configuration assuming that network provides the relevant target cell specific information via broadcasted system information blocs or via UE specific information as part of the RRC procedures, e.g . when UE mode changes.

In the following, advantages of the above embodiments are summarized .

The network can configure the users with different TTT values per measurement report trigger event and therefore provide flexible mobility robustness solutions. That is, keep the fast moving UEs out of small cells, for example, or in general, provide optimized configuration for users who are not falling into the average user profile. Embodiments of the present invention can be also used to provide an escape mechanism for users, where UEs are generally having an overall long TTT. In addition to slow trigger for general conditions, UE can have a fast trigger representing a minimum quality before RLF is indicating that a fast handover must be performed . This trigger with short TTT activates just before RLF, e.g . when other triggers events with generally long TTT are normally used to avoid excessive number of ping-pong handovers. All trigger events can have different MSE SpeedStateScalingFactors impacting the TTT parameter. Therefore enhanced measurements can use optimization of the MSE scaling factors per event. MSE can be also disabled for a certain event e.g . by setting all the scaling factors to "1.0" or e.g . by specific indication that MSE scaled parameters shall not be used or alternatively shall be used in the event evaluation.

Enhanced measurement trigger events can be used to support event optimization using both Mobility State Estimation and different source/target cell type characteristics.

For non-stationary and irregularly moving users the enhanced measurement parameters will solve the problem related to diverse user mobility profiles and that parameters don't need to be a compromise between sl owly movi ng an d fast movi ng user profi le . Th is ca n be achieved by configuring combined trigger events.

SON (Self-Organizing Networks) and CEM (customer Experience Management) can also use the mobility information and differentiate the user perfo rm a n ce by d efi n i n g th e U E s pe ci fi c p a ra m ete rs pe r measurement report trigger event. SON algorithms are typically having a problem where the generic pedestrian parameters are not optimum neither for stationary nor fast moving users. It is noted that the embodiments and the present invention in general is not limited to the specific examples given above. In particular, it is noted that different measurement trigger parameters can be defined for one measurement event. For example, timeToTrigger and also cell type and the like can be considered at the same time. Furthermore, embodiments of the present invention were described as in particular advantageous for heterogeneous networks. However, the embodiments are also applicable and advantageous for homogeneous networks. For example, individual measurement trigger parameters may be applied in order to achieve individual measurements from different UEs depending on the current network situation or the like.

As described above, embodiments of the present invention provide an apparatus and a method by which measurements are carried out and measurement reports are sent on fulfillment of measurement trigger co n d it i o n s re l a te d to m e a s u re m e n t t ri g g e r p a ra m ete rs , t h e measurements and corresponding measurement reports being defined according to predefined measurement events, wherein for at least one measurement event at least one measurement trigger parameter is independently configured from other measurement trigger parameters for other measurement events. Furthermore, an apparatus and a method are provided by which a user equipment is configured to carry out the above functions.

According to a further aspect of embodiments of the present invention, an apparatus is provided which comprises

means for carrying out measurements and sending measurement reports on fulfillment of measurement trigger conditions related to measurement trigger parameters, the measurements and corresponding measurement reports being defined according to predefined measurement events,

wherein for at least one measurement event at least one measurement trigger parameter is independently configured from other measurement trigger parameters for other measurement events. According to another aspect of embodiments of the present invention, an apparatus is provided which comprises

means for configuring a user equipment to carry out measu rements and to send measu rement reports on fu lfi l l ment of measurement trigger conditions related to measurement trigger parameters, the measurements and corresponding measurement reports being defined according to predefined measurement events,

It is to be understood that any of the above modifications can be applied singly or in combination to the respective aspects and/or embodiments to wh i ch they refe r, u n l ess they a re exp l icitly stated as excl u d i n g alternatives.

For the purpose of the present invention as described herein above, it should be noted that

- an access technology via which signaling is transferred to and from a network element may be any technology by means of which a network element or sensor node can access another network element or node (e.g . via a base station or generally an access node). Any present or future technology, such as WLAN (Wireless Local Access Network), WiMAX (Worldwide Interoperability for Microwave Access), LTE, LTE-A, Bluetooth, Infrared, and the like may be used; although the above technologies are mostly wireless access technologies, e.g . in different radio spectra, access technology in the sense of the present invention implies also wired technologies, e.g . IP based access technologies like cable networks or fixed lines but also circuit switched access technologies; access technologies may be distinguishable in at least two categories or access domains such as packet switched and circuit switched, but the existence of more than two access domains does not impede the invention being applied thereto,

- usable communication networks, stations and transmission nodes may be or comprise any device, apparatus, unit or means by which a station, entity or other user equipment may connect to and/or utilize services offered by the access network; such services include, among others, data and/or (audio-) visual communication, data download etc. ;

- a user equipment or communication network element (station) may be any device, apparatus, unit or means by which a system user or subscriber may experience services from an access network, such as a mobile phone or smart phone, a personal digital assistant PDA, or computer, or a device having a corresponding functionality, such as a modem chipset, a chip, a module etc., which can also be part of a UE or attached as a separate element to a UE, or the like;

- method steps likely to be implemented as software code portions and being run using a processor at a network element or terminal (as examples of devices, apparatuses and/or modules thereof, or as examples of entities including apparatuses and/or modules therefore), are software code independent and can be specified using any known or future developed programming language as long as the functionality defined by the method steps is preserved;

- generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the invention in terms of the functionality implemented;

- method steps and/or devices, units or means likely to be implemented as hardware components at the above-defined apparatuses, or any module(s) thereof, (e.g., devices carrying out the functions of the apparatuses according to the embodiments as described above, eNode-B etc. as described above) are hardware independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL (Transistor-Transistor Logic), etc., using for example ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components;

- devices, units or means (e.g . the above-defined apparatuses, or any one of their respective means) can be implemented as individual devices, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device, unit or means is preserved;

- an apparatus may be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of an apparatus or module, instead of being hardware implemented, be implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for execution/being run on a processor;

- a device may be regarded as an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example.

It is noted that the embodiments and examples described above are provided for illustrative purposes only and are in no way intended that the present invention is restricted thereto. Rather, it is the intention that all variations and modifications be included which fall within the spirit and scope of the appended claims.

Claims

1. An apparatus comprising

an interface unit configured to provide connection to a network, and

a processor configured

to carry out measurements and to send measurement reports on fulfillment of measurement trigger conditions related to measurement trigger parameters via the interface unit, the measurements and co rrespo n d i n g measu rement re po rts bei n g defi ned acco rd i n g to predefined measurement events,

2. The apparatus according to claim 1, wherein

the measurement trigger parameter comprises to a time parameter, wherein the measurement trigger condition is fulfilled when an entry condition for performing the measurement based on the measurement event is met during the duration specified by the time parameter.

3. The apparatus according to claim 2, wherein

the processor is configured to scale the time parameter based on a scaling factor, wherein scaling factors are individually configured for the measurement event.

4. The apparatus according to claim 3, wherein the processor is configured to scale the time parameter by selecting a scaling factor of the scaling factor configured for the measurement event.

5. The apparatus according to claim 1, wherein

the measurement trigger parameter comprises user mobility information, wherein the measurement trigger condition is fulfilled when the user mobility information defined by the measurement trigger condition coincides with actual user mobility information.

6. The apparatus according to claim 1, wherein

the measurement trigger parameter comprises a cell type parameter, wherein the measurement trigger condition is fulfilled when a cell in respect to which the measurement is to be carried out is of a cell type specified by the cell type parameter.

7. The apparatus according to any one of the claims 1 to 5, wherein for at least one measurement, the definition of the corresponding measurement trigger parameter is included in the configuration of the measurement event, or

a list of measurement trigger parameters for measurement events is provided separately.

8. The apparatus according to any one of the claims 1 to 7, wherein the processor is configured to receive measurement trigger parameters in a broadcasted system information block via the interface unit.

9. An apparatus comprising

an interface unit configured to provide connection to a network, and

a processor configured

to configure a user equipment to carry out measurements and to send measurement reports on fulfillment of measurement trigger conditions related to measurement trigger parameters, the measurements and corresponding measurement reports being defined according to predefined measurement events,

10. The apparatus according to claim 9, wherein

11. The apparatus according to claim 10, wherein

the processor is configured to configure scaling factors for the time parameter individually for the measurement event.

12. The apparatus according to claim 9, wherein

the measu rement trigger parameter com prises user mobil ity information, wherein the measurement trigger condition is fulfilled when the user mobility information defined by the measurement trigger condition coincides with actual user mobility information.

13. The apparatus according to claim 9, wherein

14. The apparatus according to any one of the claims 9 to 13, wherein for at least one measurement, the definition of the corresponding measurement trigger parameter is included in the configuration of the measurement event, or

15. The apparatus according to any one of the claims 9 to 14, wherein the processor is configured to send measurement trigger parameters in a broadcasted system information block via the interface unit.

16. A method comprising

carrying out measurements and

sending measurement reports on fulfillment of measurement trigger conditions related to measurement trigger parameters, the measurements and corresponding measurement reports being defined according to predefined measurement events,

17. The method according to claim 16, wherein

18. The method according to claim 17, further comprising

scaling the time parameter based on a scaling factor, wherein scaling factors are individually configured for the measurement event.

19. The method according to claim 18, further comprising

scaling the time parameter by selecting a scaling factor of the scaling factor configured for the measurement event.

20. The method according to claim 16, wherein

21. The method according to claim 16, wherein

22. The method according to any one of the claims 16 to 21, wherein for at least one measurement, the definition of the corresponding measurement trigger parameter is included in the configuration of the measurement event, or

23. The method according to any one of the claims 16 to 22, further comprising

receiving measurement trigger parameters during an idle mode in a broadcasted system information block.

24. A method comprising

configuring a user equipment to carry out measurements and to send measurement reports on fulfillment of measurement trigger conditions related to measurement trigger parameters, the measurements and corresponding measurement reports being defined according to predefined measurement events,

25. The method according to claim 24, wherein

26. The method according to claim 25, further comprising

configuring scaling factors for the time parameter individually for the measurement event.

27. The method according to claim 24, wherein

28. The method according to claim 24, wherein

29. The method according to any one of the claims 24 to 28, wherein for at least one measurement, the definition of the corresponding measurement trigger parameter is included in the configuration of the measurement event, or

30. The method according to any one of the claims 24 to 29, further comprising

sending measurement trigger parameters in a broadcasted system information block.

31. A computer program product comprising code means for performing a method according to any one of claims 16 to 30 when run on a processing means or module.

32. The computer program product according to claim 32, wherein the computer program product is embodied on a computer-readable medium.