USOO8626175B2
`
`(12) United States Patent
`Jorguseski et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 8.626,175 B2
`Jan. 7, 2014
`
`(54) METHOD AND SYSTEM FOR AUTOMATIC
`COVERAGE ASSESSMENT FOR
`COOPERATING WIRELESS ACCESS
`NETWORKS
`
`(58) Field of Classification Search
`USPC ....................... 455/446, 422.1, 450, 418, 423
`See application file for complete search history.
`References Cited
`
`(56)
`
`Appl. No.:
`
`PCT Fled:
`
`Dec. 16, 2010
`
`(21)
`(22)
`(86)
`
`(75) Inventors: Ljupco Jorguseski, Rijswijk (NL);
`Remco Litjens, Voorschoten (NL);
`Haibin Zhang. The Hague (NL); Victor
`Pais, Rijswijk (NL)
`(73) Assignees: Koninklijke KPN N.V., The Hague
`(NL); Nederlandse Organisatie voor
`Toegepast-Natuurwetenschappelijk
`Onderzoek TNO, Delft (NL)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 23 days.
`13/516,905
`
`(*)
`
`Notice:
`
`PCT/EP2010/069908
`
`PCT NO.:
`S371 (c)(1),
`(2), (4) Date:
`Jun. 18, 2012
`(87) PCT Pub. No.: WO2011/080096
`PCT Pub. Date: Jul. 7, 2011
`
`(65)
`
`(30)
`
`Prior Publication Data
`US 2012/0264439 A1
`Oct. 18, 2012
`
`Foreign Application Priority Data
`
`Dec. 21, 2009
`
`(EP) ..................................... O918O130
`
`(51)
`
`(52)
`
`Int. C.
`H04740/00
`U.S. C.
`USPC ........ 455/446; 455/422.1; 455/450; 455/418;
`455/423
`
`(2009.01)
`
`U.S. PATENT DOCUMENTS
`
`8,301,162 B2 * 10/2012 Ward ......................... 455,456.1
`2004/OOO2328 A1
`1/2004 Chandra et al.
`2007,0004394 A1
`1/2007 Chu et al.
`2008/0051 129 A1
`2/2008 Abe et al. ................... 455,550.1
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`WO
`
`T 2009
`2O76093 A1
`8, 1997
`WO97.315O2
`OTHER PUBLICATIONS
`
`PCT International Search Report and Written Opinion, PCT Interna
`tional Application No. PCT/EP2010/069908 dated May 13, 2011.
`European Search Report, European Patent Application No.
`09180 130.8 dated Aug. 9, 2010.
`"3rd Generation Partnership Project: Technical Specification Group
`Radio Access Network; Stage 2 Functional Specification of Location
`Services in UTRAN. 3GTS 25.305 V2.0.0. Dec. 1999, pp. 1-38.
`* cited by examiner
`Primary Examiner — Nghi H Ly
`(74) Attorney, Agent, or Firm — McDonnell Boehnen
`Hulbert & Berghoff LLP
`(57)
`ABSTRACT
`The invention relates a method and system for assessing
`coverage of a wireless access network within a desired area
`via cooperating wireless access networks and terminals
`capable of measurement and reporting across the different
`wireless access networks. The cooperation refers to, among
`other things, the ability of obtaining coverage assessment for
`one of the wireless access networks using results of the mea
`Surements collected at one of the other wireless access net
`works. In this manner, more accurate and complete coverage
`assessment may be obtained, relative to the prior art
`approaches.
`
`15 Claims, 4 Drawing Sheets
`
`OMC (1st Network)
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`
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`OMC (2nd Network)
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`1.
`METHOD AND SYSTEM FOR AUTOMATIC
`COVERAGE ASSESSMENT FOR
`COOPERATING WIRELESS ACCESS
`NETWORKS
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`
`The present application is a national stage entry of PCT/
`EP2010/069908, filed Dec. 16, 2010, and claims priority to
`EP 09180130.8, filed Dec. 21, 2009. The full disclosures of
`EP 09180130.8 and PCT/EP2010/069908 are incorporated
`herein by reference.
`
`FIELD OF THE INVENTION
`
`The invention relates to the field of telecommunications
`infrastructures. More specifically, the invention relates to the
`field of coverage assessment in telecommunications infra
`structures comprising wireless access networks.
`
`BACKGROUND OF THE INVENTION
`
`2
`As the foregoing illustrates, there exists a need in the art for
`a system and method for generating a coverage assessment in
`a telecommunications infrastructure in a manner that mini
`mizes or eliminates at least some of the drawbacks of the
`current approaches described above.
`
`SUMMARY OF THE INVENTION
`
`An automatic coverage assessment system configured for
`generating a coverage assessment for a second wireless
`access network of a telecommunications infrastructure com
`prising a first wireless access network and the second wireless
`access network is disclosed. The first and second wireless
`access networks are capable of providing services to a plu
`rality of terminals such as e.g. user terminals.
`The system includes an information collector and a cover
`age estimator. In one embodiment, the information collector
`may be included within the first wireless access network,
`while the coverage estimator may be included within the
`second wireless access network. The information collector
`may be configured for collecting information from terminals
`via the first wireless access network. In another embodiment,
`the information collector and the coverage estimator may be
`included within the second wireless access network. In Such
`an embodiment, the information collector may be configured
`for collecting information from terminals via the first and the
`second wireless access networks.
`The coverage estimator may be configured for receiving
`information from the information collector. The information
`collector may be configured to select one or more terminals
`from at least part of the plurality of the terminals, where the at
`least part of the plurality of the terminals is capable of com
`municating with both the first wireless access network and the
`second wireless access network. The information collector
`may further be configured to obtain measurement informa
`tion indicative of the signals measured from the second wire
`less access network by the selected one or more terminals and
`provide the measurement information to the coverage estima
`tor. In one embodiment, the information collector may obtain
`the measurement information in response to an instruction
`provided to the selected one or more terminals to measure
`signals from the second wireless access network (Suitable for
`generating the coverage assessment of the second wireless
`access network). The measurement information may e.g.
`include signal strength, cell identifications of the second
`wireless access network, information related to the location
`of the terminal (e.g. GPS coordinates), and/or information
`that can be used for location estimation (including e.g. signal
`strength indications, timing information, power information).
`The coverage estimator may be configured to obtain the mea
`Surement information from the information collector and,
`based on the obtained measurement information, generate the
`coverage assessment for the second wireless access network
`of the telecommunications infrastructure.
`As used herein, the phrase “terminal capable of communi
`cation with both the first and second wireless access net
`works’ is intended to cover not only wireless communication,
`but also include an indirect communication path (e.g. wire
`lessly to the first network and then via some fixed connection
`to the second network or via a third network to the second
`network). Furthermore, the communication with the first net
`work could, but does not have to, take place at the same time
`as the communication with the second network.
`Optionally, the automatic coverage assessment system
`may further include a first database connected to the infor
`mation collector and configured for storing the measurement
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`Wireless access networks are used to provide terrestrial
`coverage via placement of base stations throughout the
`desired coverage area. In order to provide adequate service to
`the clients, wireless operators constantly evaluate the cover
`age area of their wireless access networks. Such an evaluation
`may, for example, be done in the planning phase via coverage
`calculations based on models for the attenuation of the radio
`signals, terrain configuration data and the configuration data
`about the type and placement of the base stations. Such cal
`culations provide, for the area under consideration and for
`each base station included in the calculations, a reasonably
`complete indication of the estimated signal strength but only
`with a limited accuracy, given the necessary simplifications
`made in the attenuation model and the limited degree of
`details in the underlying databases. In their operational pro
`cesses, wireless operators frequently use drive tests in order to
`assess the coverage of their wireless access networks. These
`drive tests consist of measurement routes that are traversed by
`a measurement terminal often mounted on a vehicle, as illus
`trated in FIG. 1, where the measurement route is shown with
`a line 1 and the measurement terminal (vehicle) location is
`shown as a dot 10. Such measurements provide, for each base
`station included in the measurement, a reasonably accurate
`indication of the signal strength but only for the very limited
`set of locations along the measurement route 1. Besides the
`drive measurements the operators collect statistical informa
`tion from the network nodes about events that can be used to
`roughly indicate coverage problems such as failed connec
`tions, inter-radio access technology (inter-RAT) handovers
`and cell reselections, etc.
`The coverage assessment options presented above have a
`number of drawbacks. One is that the planning process is
`generally characterised by a certain degree of inaccuracy due
`to e.g. estimation errors in the radio propagation modelling
`and/or inaccurate terrain configuration data. Another draw
`back is that the drive tests provide the coverage assessment
`only along the measurement route. Moreover, drive tests are
`too costly for estimation of the overall coverage. Yet another
`drawback is that the network statistics collection has its basic
`limitation in that only the signals and events for the terminals
`that are connected to/camping on the network may be
`reported (and not the terminals that do not have coverage).
`Moreover, such statistics can only roughly indicate the loca
`tions of coverage gaps.
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`information and/or a second database connected to the cov
`erage estimator and configured for storing the coverage
`aSSeSSment.
`In various embodiments, the first and second access wire
`less access network respectively may for example include, 5
`respectively, a first network using a first radio access technol
`ogy and a second network using a second radio access tech
`nology, a first network using a first radio spectrum and a
`second network using a second radio spectrum, a first net
`work of a first network operator and a second network of a
`second network operator, or a first (sub)network and a second
`(sub)network of a same network operator.
`In one embodiment, the telecommunications infrastructure
`may include at least one operations and maintenance centre,
`the first wireless access network may include a number of first 15
`base stations, and the second wireless access network may
`include a number of second base stations. In Such an embodi
`ment, at least a part of the automatic coverage assessment
`system may be contained in the operations and maintenance
`centre and/or the first and/or second base stations.
`Based on the generated coverage assessment, the coverage
`estimator may further be configured to e.g. select geographi
`cal areas where installation of new base stations could be
`considered and/or identify existing base stations for which
`adjustments and/or extensions could be considered. Further,
`using the generated coverage assessment, the coverage esti
`mator may be configured to generate one or more instructions
`based on a comparison of the coverage assessment with a
`previously generated coverage assessment.
`A corresponding method, computer program, mobile user
`terminal, and network nodes that allow generating a coverage
`assessment for a second wireless access network of a tele
`communications infrastructure as defined above are also dis
`closed.
`The disclosed systems and a method are implemented
`based on the observation that an assessment of the coverage of
`a wireless access network within a desired area may be
`obtained via cooperating wireless access networks and termi
`nals capable of measurement and reporting across the differ
`ent wireless access networks. The cooperation refers to,
`among other things, the ability of generating coverage assess
`ment for one of the wireless access networks using results of
`the measurements collected through one of the other wireless
`access networks. In this manner, more accurate and/or com
`plete and/or less costly coverage assessment may be obtained, 45
`relative to the prior art approaches. Furthermore, the dis
`closed system and method may allow obtaining a coverage
`assessment for areas which are currently “out of coverage' by
`the prior art solutions.
`One embodiment of the present invention provides a trig- 50
`ger configured for triggering the information collector to
`select the one or more terminals. The trigger may be included
`within the first wireless access network and may be event
`based or periodical, with period T. In order to decrease or
`avoid collection of excessive location and/or measurement 55
`information, the trigger may be applied selectively depending
`on where and/or when the coverage assessment is needed.
`Another embodiment allows avoiding excessive collection
`of information from terminals via the first wireless access
`network by obtaining location information for at least one of 60
`the at least part of the plurality of terminals prior to selecting
`the one or more terminals. The location information may be
`determined for terminals either in an idle mode (i.e. without
`an existing connection) or in an active mode (i.e. with an
`existing connection), as long as these terminals are capable of 65
`communicating with both the first and the second wireless
`access networks.
`
`4
`The location information may be obtained via location
`estimation techniques, which are known in the art, and/or via
`each of the at least part of the plurality of terminals providing
`their location information to the information collector (e.g.
`via terminals equipped with GPS receivers capable of deter
`mining their locations).
`When the location information is obtained from the termi
`nals, a radio resource control (RRC) channel may be used to
`convey the location information (as well as the measurement
`information) from the terminals to the information collector
`(possibly via the first wireless access network). A common
`data connection (e.g. via the wireless network that is currently
`serving the terminal) may also be used to convey information
`from the terminals to the information collector. In the remain
`der of the text, whenever an RRC channel is mentioned to
`convey information between two entities, it is implied that
`any other communication channel. Such as e.g. a common
`data connection, may also be used.
`Based on the location information, only terminals located
`in the area for which the coverage assessment should be
`generated may be selected for obtaining the measurement
`information.
`Alternatively, the location information may be determined
`by the first wireless access network (e.g., by the information
`collector) up to the cell level or group of cells (e.g., location/
`routing/tracking area level) by selecting the at least part of the
`plurality ofterminals to be terminals in a specified geographi
`cal area. For example, some orall terminals in a particular city
`area, a whole city, a district, a province/state, etc. may be
`selected to be the terminals from which then the one or more
`terminals are selected. This embodiment may be advanta
`geous when location estimation techniques are not available,
`when exact location information of the terminals is not
`needed for selecting the terminals that should perform the
`measurements or when only coarse location information (e.g.
`cell-level location information) is sufficient.
`One embodiment of the present invention specifies provid
`ing location information valid upon obtaining the measure
`ment information for at least one of the selected one or more
`terminals.
`Sometimes it may be possible that the location of the
`selected terminals when they are actually obtaining the mea
`surement information is different from what it was when the
`location information was obtained by the first wireless access
`network. This could happen when the terminal moves during
`this (small) period. Therefore, such an embodiment allows
`updating the location information for at least one of the
`selected one or more terminals with the location information
`of the terminals at the time when the measurement informa
`tion is obtained by the terminals. In case that the location
`information is provided by the terminal itself, the new loca
`tion may be sent along with the measurement results. In case
`that the location is estimated by the first wireless access
`network, the network may re-estimate the location when it
`obtains the measurement results. If the new location is differ
`ent from the old one, the new location may be used by updat
`ing the old location information.
`Other times, location information or a location estimation
`may be provided after a terminal has been added to the set of
`measuring terminals (selected terminals). Therefore, such an
`embodiment also allows providing location information for at
`least one of the selected one or more terminals valid at the
`time of the measurement.
`One embodiment sets forth associating the location infor
`mation with at least one of the selected one or more terminals
`and providing the location information associated with the at
`least one of the selected one or more terminals to the coverage
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`BRIEF DESCRIPTION OF THE DRAWINGS
`
`In the drawings:
`FIG. 1 provides a schematic illustration of a drive test
`measurement of the wireless access network coverage,
`according to prior art;
`
`5
`estimator. Such an embodiment advantageously allows pro
`viding the coverage estimator not only with the measurement
`information, but also with the location information associated
`with at least one of the selected one or more terminals, from
`which the coverage estimator may generate the coverage
`assessment (i.e., a representation of locations/pixels and e.g.
`associated signal strengths of the second wireless access net
`work).
`In one further embodiment, the information collector may
`be further configured to update the selected one or more
`terminals to eliminate terminals that are associated with the
`location information indicative of a location not included in a
`predefined location area for which the coverage assessment is
`generated, prior to forwarding the location information asso
`ciated with the at least some of the selected one or more
`terminals to the coverage estimator. This embodiment may be
`particularly advantageous when e.g. one of the selected ter
`minals moved during the period between obtaining the initial
`location information and actually performing the measure
`ments as instructed by the information collector. If the new
`location of such a terminal is out of the area for which the
`coverage assessment should be generated, the new location
`and the corresponding measurement may be stored in a data
`base for future use, but not used at the moment for the cov
`erage assessment of the second wireless access network.
`In one embodiment, the information collector may be con
`figured to select the one or more terminals when the one or
`more terminals comprise terminals in a predefined location
`area for which the coverage assessment is generated. This
`specifies one criterion that may be advantageously applied in
`selecting the one or more terminals for obtaining the mea
`Surement information.
`In other embodiments, the information collector may be
`configured to select the one or more user terminals when the
`one or more user terminals satisfy one or more of different
`criteria. For example, one criterion may be that the one or
`more user terminals use a predefined service via the first
`wireless access network while, according to operator policy,
`usage of the predefined service is preferred via the second
`wireless access network. Another criterion may be that a
`self-optimization or a manual optimization of a radio cover
`age is performed for one or more base stations within the
`second wireless access network and the one or more user
`terminals comprise user terminals in those cells within the
`first wireless access network that have inter-RAT neighbour
`relation with cells within the second wireless access network
`where the optimization takes place. Yet another criterion may
`be that the one or more user terminals comprise user terminals
`from one or more cells in the first wireless access network
`associated with a planned coverage overlap with one or more
`cells in the second wireless access network where the cover
`age should be assessed.
`In various embodiments, an RRC signalling channel may
`be used to convey information between any of the terminals
`and the first and second wireless access networks.
`Hereinafter, embodiments of the invention will be
`described in further detail. It should be appreciated, however,
`that these embodiments may not be construed as limiting the
`Scope of protection for the present invention.
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`FIG. 2 provides a schematic illustration of a telecommu
`nications infrastructure comprising two wireless access net
`works and terminals Supporting both networks, according to
`one embodiment of the present invention;
`FIG. 3 illustrates an example of implementing a coverage
`assessment system, according to one embodiment of the
`present invention; and
`FIG. 4 provides a flow diagram of method steps for gener
`ating a coverage assessment for one wireless access network
`in a telecommunications infrastructure illustrated in FIG. 2,
`according to one embodiment of the present invention.
`
`DETAILED DESCRIPTION OF THE DRAWINGS
`
`FIG. 2 provides a schematic illustration of a telecommu
`nications infrastructure 200, according to one embodiment of
`the present invention. The telecommunications infrastructure
`200 comprises a first wireless access network and a second
`wireless access network, represented in FIG. 2 as networks
`2A and 2B, respectively (including base stations, e.g. NodeBS
`in UMTS and/or eNodeBs in LTE) defining respective cov
`erage areas 3A (solidlines) and 3B (dashed lines). It should be
`noted that the dimensions of the coverage areas 3A, 3B may
`not be constant in time.
`A plurality of mobile terminals is associated with the first
`and second wireless access networks 2A, 2B. At least a part of
`these terminals can Support multiple radio access systems
`(this part of the terminals is shown in FIG. 2 as terminals 5
`which are capable of communicating with both the first and
`second wireless access networks 2A, 2B). The invention
`described herein is applicable in, but not limited to, areas
`where several wireless access networks are cooperating, for
`example, in terms of inter-RAT handover and/or cell reselec
`tion.
`In one embodiment, the first and second wireless access
`networks 2A, 2B may be operated with a single operations
`and maintenance centre (OMC), not shown in FIG.2. The first
`and second wireless access networks 2A, 2B may e.g. differin
`radio access technology (e.g. GSM and UMTS or UMTS and
`LTE) or the used frequency spectrum (e.g. the 900 MHz and
`1800 MHz frequency bands)
`In another embodiment, each of the first and second wire
`less access networks 2A, 2B is operated with a corresponding
`OMC (not shown in FIG. 2). The corresponding OMCs may
`be at least connected to one another in order to exchange
`information for generating a coverage assessment.
`Further network elements may be arranged in the telecom
`munications infrastructure 200 of FIG. 2 between the one or
`more OMCs and the networks 2A and 2B of the correspond
`ing wireless access technologies, as known to the person
`skilled in the art.
`In the telecommunications infrastructure 200 of FIG. 2, a
`coverage assessment system, the operation of which will be
`further described with reference to FIG. 3, may be included
`within the one or more OMCs. However, the coverage assess
`ment system is not necessarily implemented in Such a cen
`tralized manner, but may also be decentralised by implement
`ing coverage assessment functionality in other network
`elements (such as base stations) and using connections
`between these elements. Hybrid implementations are also
`envisaged. Signals for generating coverage assessment can be
`exchanged over management or traffic interfaces.
`FIG. 3 illustrates an example of implementing a coverage
`assessment system 300, according to one embodiment of the
`present invention. As shown, the coverage assessment system
`300 includes an information collector 7 and a coverage esti
`mator 8. The information collector 7 is configured for collect
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`ing information from some of the terminals 5 via the first
`wireless access network 2A and providing the information to
`the coverage estimator 8. The coverage estimator 8 is config
`ured for connecting to and receiving information from the
`information collector 7 and, based on the received informa
`tion, generating the coverage assessment for the second wire
`less access network 2B.
`In the embodiment shown in FIG. 3, the information col
`lector 7 is included within an OMC 9A of the first wireless
`access network 2A and the coverage estimator 8 is included
`within an OMC9B of the second wireless access network 2B.
`Alternatively, the first and second wireless access networks
`2A, 2B may share the same OMC.
`In one embodiment, the information collector 7 and the
`coverage estimator 8 may be largely implemented as Software
`executed by a processor and making use of memory (not
`shown in FIG. 3). In other embodiments, the information
`collector 7 and the coverage estimator 8 may be implemented
`in hardware or in a combination of software and hardware.
`Optionally, the information collector 7 may be connected
`to a database 11A configured to store the location and mea
`surement information (described in greater detail in FIG. 4).
`Also optionally, the coverage estimator 8 may be connected to
`a database 11B configured to store the results of coverage
`assessments for future use.
`FIG. 4 provides a flow diagram of method steps for gener
`ating a coverage assessment for one wireless access network
`in a telecommunication infrastructure comprising two or
`more cooperating wireless access networks using the cover
`age assessment system 300, according to one embodiment of
`the present invention. While the method steps are described in
`conjunction with FIGS. 2 and 3, persons skilled in the art will
`recognize that any system configured to perform the method
`steps, in any order, is within the scope of the present inven
`tion. Furthermore, while the method is illustrated to include
`only two cooperating wireless access networks, the method is
`also applicable for any arbitrary number of cooperating wire
`less access networks.
`In one embodiment of FIG. 4, consider that at a given
`location the first wireless access network 2A has a good radio
`coverage (and, therefore, the terminals 5 can connect to it) but
`there is no or poor radio coverage from the second wireless
`access network 2B. Further consider that the first wireless
`access network 2A is a 3G UMTS network, while the second
`wireless access network 2B is an LTE network. For an opera
`tor who already has an UMTS network, the UMTS network
`typically has a more extended coverage than the LTE net
`work, especially at the beginning of the LTE deployment. As
`previously described, the terminals 5 are capable of commu
`nicating with both the first and second wireless access net
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`works 2A, 2B.
`The method for generating a coverage assessment may
`begin with an optional step (not shown in FIG. 4) where the
`information collector 7 requests, via the 3GPP Itf-N interface
`to the UMTS network (the first wireless access network 2A in
`this example), the location of all or a group of terminals 5
`camping on or connected to the UMTS network. The UMTS
`network can either use its terminal positioning technologies
`specified in the 3GPP standard TS 25.305 to estimate the
`location of terminals, or ask the terminals via RRC signalling
`to provide the location information in case that the terminals
`are equipped with GPS.
`Alternatively, the location information may be determined
`by the UMTS network (e.g., by the information collector 7 or
`some other module within the UMTS network) up to the cell
`level or group of cells (e.g., location/routing/tracking area
`level) by selecting the terminals in a specified geographical
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`area. For example, some orall of the terminals 5 in a particular
`city area, a whole city, a district, a province, or a state may be
`selected for performing the measurements described below.
`Such an implementation may be advantageous when location
`estimation techniques are not available, when exact location
`information of the terminals 5 is not needed for selecting the
`terminals that should perform the measurements or when
`only coarse location information (e.g. cell-level location
`information) is sufficient.
`In one embodiment, the coverage assessment system 300
`may include a trigger for triggering the procedure of gener
`ating the coverage assessment, optionally including the step
`of obtaining the location information for the terminals 5 using
`any of the approaches discussed above. The trigger may be
`event-based (e.g. the instruction from the coverage estimator
`8 to obtain measurement information) or periodical, with
`period T.
`In step 410, the information collector 7 selects one or more
`of the terminals 5 for obtaining measurement information.
`This instruction may also be sent via the RRC signalling of
`the UMTS network. It should be noted that when the location
`information is obtained prior to step 410, then in step 410 only
`terminals located in the area for which the coverage assess
`ment should be generated may be selected for obtaining the
`measurement information, thus avoiding collection of exces
`sive measurement information.
`The information collector 7 may also be configured to
`select the one or more of the terminals 5 according to one of
`the following alternative embodiments. In one embodiment,
`those terminals are selected that use a particular service via
`the UMTS network while, according to the operator policy,
`usage of that service is preferred via the LTE network. In
`another embodiment, a self-optimization or a manual optimi
`Zation of a radio coverage may be performed for one or more
`base stations within the LTE network, and then the selected
`one or more terminals only comprise terminals in those cells
`within the UMTS network that have inter-RAT neighbour
`relation with cells of the LTE network where the optimization
`takes place. In yet another embodiment, the selected one or
`more terminals comprise terminals from one or more cells in
`the UMTS network where there is a planned coverage overlap
`with one or more cells in the second wireless access network
`2B where the coverage should be assessed.
`Persons skilled in the art will be able to complement the
`selection criteria described herein with additional selection
`criteria that may be relevant for the assessment of the cover
`age of the second wireless access network 2B.
`The method then continues to step 420, where the infor
`mation collector 7 instructs the selected one or more termi
`nals, via the UMTS network, to measure signals from the LTE
`network. In step 430, the information collector 7 obtains
`measurement information indicative of the signals measured
`from the LTE network by the selected one or more terminals.
`The measurement information may e.g. include indicat