U.S. patent number RE48,089 [Application Number 16/224,047] was granted by the patent office on 2020-07-07 for method and system for automatic coverage assessment for cooperating wireless access networks.
This patent grant is currently assigned to Koninklijke KPN N.V.. The grantee listed for this patent is Koninklijke KPN N.V., Nederlandse Organisatie voor Toegepast-Natuurwetenschappelijk Onderzoek TNO. Invention is credited to Ljupco Jorguseski, Remco Litjens, Adrian Victor Pais, Haibin Zhang.
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United States Patent |
RE48,089 |
Jorguseski , et al. |
July 7, 2020 |
Method and system for automatic coverage assessment for cooperating
wireless access networks
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 measurements collected at one of the other wireless
access networks. In this manner, more accurate and complete
coverage assessment may be obtained, relative to the prior art
approaches.
Inventors: |
Jorguseski; Ljupco (Rijswijk,
NL), Litjens; Remco (Voorschoten, NL),
Zhang; Haibin (The Hague, NL), Pais; Adrian
Victor (Rijswijk, NL) |
Applicant: |
Name |
City |
State |
Country |
Type |
Koninklijke KPN N.V.
Nederlandse Organisatie voor Toegepast-Natuurwetenschappelijk
Onderzoek TNO |
Rotterdam
The Hague |
N/A
N/A |
NL
NL |
|
|
Assignee: |
Koninklijke KPN N.V.
(Rotterdam, NL)
|
Family
ID: |
41785571 |
Appl.
No.: |
16/224,047 |
Filed: |
December 18, 2018 |
PCT
Filed: |
December 16, 2010 |
PCT No.: |
PCT/EP2010/069908 |
371(c)(1),(2),(4) Date: |
June 18, 2012 |
PCT
Pub. No.: |
WO2011/080096 |
PCT
Pub. Date: |
July 07, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
13516905 |
Dec 16, 2010 |
8626175 |
Jan 7, 2014 |
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Foreign Application Priority Data
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Dec 21, 2009 [EP] |
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09180130 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
16/18 (20130101); H04W 16/18 (20130101); H04W
24/06 (20130101); H04W 24/06 (20130101) |
Current International
Class: |
H04W
40/00 (20090101); H04W 16/18 (20090101); H04W
24/06 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2076093 |
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Jul 2009 |
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EP |
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2976993 |
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Jul 2009 |
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EP |
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WO1997/31502 |
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Aug 1997 |
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WO |
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WO-9731502 |
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Aug 1997 |
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WO |
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WO2009093960 |
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Jul 2009 |
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WO |
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Other References
3GPP TSG RAN WG2 #72, R2-106442, Jacksonville, FL, USA, Nov. 15-19,
2010, Method for ANR support in UTRAN. cited by applicant .
3GPP TSG-RAN2#67bis, R2-095954, Miyazaki, Japan, Oct. 12-16, 2009,
Common pilot measurements for MDT. cited by applicant .
PCT International Search Report and Written Opinion, PCT
International Application No. PCT/EP2010/069908 dated May 13, 2011.
cited by applicant .
European Search Report, European Patent Application No. 09180130.8
dated Aug. 9, 2010. cited by applicant .
"3rd Generation Partnership Project: Technical Specification Group
Radio Access Network; Stage 2 Functional Specification of Location
Services in UTRAN", 3G TS 25.305 V2.0.0., Dec. 1999, pp. 1-38.
cited by applicant.
|
Primary Examiner: Lie; Angela M
Attorney, Agent or Firm: McDonnell Boehnen Hulbert &
Berghoff LLP
Claims
The invention claimed is:
1. An automatic coverage assessment system configured for
generating a coverage assessment for a second wireless access
network of a telecommunications infrastructure comprising a first
wireless access network and the second wireless access network, the
first and second wireless access networks capable of providing
services to a plurality of terminals, the system comprising: an
information collector; and a coverage estimator, wherein the
information collector is configured to: (i) select one or more
terminals from at least part of the plurality of the terminals, the
at least part of the plurality of the terminals capable of
communicating with both the first wireless access network and the
second wireless access network, (ii) instruct the selected one or
more terminals to measure signals from the second wireless access
network, (iii) obtain measurement information indicative of the
signals measured from the second wireless access network by the
selected one or more terminals, and (iv) provide the measurement
information to the coverage estimator, and wherein the coverage
estimator is configured to: (i) obtain the measurement information
from the information collector, and (ii) based on the obtained
measurement information, generate the coverage assessment for the
second wireless access network of the telecommunications
infrastructure.
2. The automatic coverage assessment system of claim 1, wherein the
system further comprises a trigger configured for triggering the
information collector to select the one or more terminals.
3. The automatic coverage assessment system of claim 1, wherein the
information collector is further configured to obtain location
information for at least one of the at least part of the plurality
of terminals prior to selecting the one or more terminals.
4. The automatic coverage assessment system of claim 3, wherein the
information collector is further configured to associate the
location information with at least one of the selected one or more
terminals and provide the location information associated with the
at least one of the selected one or more terminals to the coverage
estimator.
5. The automatic coverage assessment system of claim 1, wherein the
information collector is further configured to provide location
information valid upon obtaining the measurement information for at
least one of the selected one or more terminals.
6. An automatic coverage assessment method for generating a
coverage assessment for a second wireless access network of a
telecommunications infrastructure comprising a first wireless
access network and the second wireless access network, the first
and second wireless access networks capable of providing services
to a plurality of terminals, the method comprising: (i) collecting,
at an information collector, information from terminals by:
selecting one or more terminals from at least part of the plurality
of the terminals, the at least part of the plurality of the
terminals capable of communicating with both the first wireless
access network and the second wireless access network, instructing
the selected one or more terminals to measure signals from the
second wireless access network, obtaining measurement information
indicative of the signals measured from the second wireless access
network by the selected one or more terminals, and providing the
measurement information to a coverage estimator; and (ii)
generating, at the coverage estimator, the coverage assessment for
the second wireless access network by: obtaining the measurement
information from the information collector, and based on the
obtained measurement information, generating the coverage
assessment for the second wireless access network of the
telecommunications infrastructure.
7. The automatic coverage assessment method of claim 6, further
comprising the step of triggering the information collector to
select the one or more terminals.
8. The automatic coverage assessment method of claim 6, further
comprising the step of obtaining location information for at least
one of the at least part of the plurality of terminals prior to
selecting the one or more terminals.
9. The automatic coverage assessment method of claim 8, further
comprising the step of providing the location information valid
upon obtaining the measurement information for at least one of the
selected one or more terminals.
10. The automatic coverage assessment method of claim 8, further
comprising: associating the location information with at least one
of the selected one or more terminals, and forwarding the location
information associated with the at least one of the selected one or
more terminals to the coverage estimator.
11. A mobile user terminal configured for use in .[.the method of
claim 6.]. .Iadd.an automatic coverage assessment method for
generating a coverage assessment for a second wireless access
network of a telecommunications infrastructure, the
telecommunications infrastructure comprising a first wireless
access network and the second wireless access network, wherein the
first and second wireless access networks are capable of providing
services to a plurality of terminals, and wherein .Iaddend.the
.Iadd.mobile user .Iaddend.terminal .[.comprising.].
.Iadd.comprises.Iaddend.: means for measuring signals from the
second wireless access network; and means for providing the
measurement information to at least one of .[.the.]. .Iadd.an
.Iaddend.information collector .[.and the.]. .Iadd.or a
.Iaddend.coverage estimator based on the measured signals.Iadd.,
wherein the mobile user terminal is further configured to: receive
an instruction from the information collector to measure signals,
wherein the information collector carries out operations including
collecting information from terminals by: selecting one or more
terminals from at least part of the plurality of the terminals, the
at least part of the plurality of the terminals capable of
communicating with both the first wireless access network and the
second wireless access network, instructing the selected one or
more terminals to measure signals from the second wireless access
network, obtaining measurement information indicative of the
signals measured from the second wireless access network by the
selected one or more terminals, and providing the measurement
information to a coverage estimator; and measure signals from the
second wireless access network; wherein the coverage estimator
carries out operations including generating the coverage assessment
for the second wireless access network by: obtaining the
measurement information from the information collector, and based
on the obtained measurement information, generating the coverage
assessment for the second wireless access network of the
telecommunications infrastructure. .Iaddend.
12. A .[.computer program comprising software code portions
configured for,.]. .Iadd.non-transitory computer-readable medium
having instructions stored thereon that, .Iaddend.when executed by
a processor .Iadd.of a telecommunications infrastructure comprising
a first wireless access network and the second wireless access
network, the first and second wireless access networks capable of
providing services to a plurality of terminals, causes the
telecommunications infrastructure to carry out operations of an
automatic coverage assessment method for generating a coverage
assessment for the second wireless access network, the operations
including: .Iaddend..[., performing one or more steps of the method
of claim 6.]. .Iadd.(i) collecting, at an information collector,
information from terminals by: selecting one or more terminals from
at least part of the plurality of the terminals, the at least part
of the plurality of the terminals capable of communicating with
both the first wireless access network and the second wireless
access network, instructing the selected one or more terminals to
measure signals from the second wireless access network, obtaining
measurement information indicative of the signals measured from the
second wireless access network by the selected one or more
terminals, and providing the measurement information to a coverage
estimator; and (ii) generating, at the coverage estimator, the
coverage assessment for the second wireless access network by:
obtaining the measurement information from the information
collector, and based on the obtained measurement information,
generating the coverage assessment for the second wireless access
network of the telecommunications infrastructure. .Iaddend.
13. A network node for use in a telecommunications infrastructure
comprising a first wireless access network and a second wireless
access network, the first and second wireless access networks
capable of providing services to a plurality of terminals, the node
comprising: means for selecting one or more terminals from at least
part of the plurality of the terminals, the at least part of the
plurality of the terminals capable of communicating with both the
first wireless access network and the second wireless access
network; means for instructing the selected one or more terminals
to measure signals from the second wireless access network, means
for obtaining measurement information indicative of the signals
measured from the second wireless access network by the selected
one or more terminals; and means for providing the measurement
information to a coverage estimator, wherein the coverage estimator
is configured to generate the coverage assessment for the second
wireless access network of the telecommunications infrastructure
based on the measurement information provided by the network
node.
14. The network node of claim 13, wherein the coverage estimator is
included within the network node.
15. A network node for use in a telecommunications infrastructure
comprising a first wireless access network and a second wireless
access network, the first and second wireless access networks
capable of providing services to a plurality of terminals, the node
comprising: means for obtaining measurement information from an
information collector; and means for generating the coverage
assessment for the second wireless access network of the
telecommunications infrastructure based on the obtained measurement
information, wherein the information collector is configured to:
(i) select one or more terminals from at least part of the
plurality of the terminals, the at least part of the plurality of
the terminals capable of communicating with both the first wireless
access network and the second wireless access network, (ii)
instruct the selected one or more terminals to measure signals from
the second wireless access network, (iii) obtain measurement
information indicative of the signals measured from the second
wireless access network by the selected one or more terminals, and
(iv) provide the measurement information to the network node.
Description
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 infrastructures
comprising wireless access networks.
BACKGROUND OF THE INVENTION
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 coverage 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 calculations 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 data bases. In their
operational processes, 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
illustrated 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 information from the network nodes about events
that can be used to roughly indicate coverage problems such as
failed connections, 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 drawback 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 locations of coverage gaps.
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 minimizes 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 comprising 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 plurality of terminals such as e.g. user
terminals.
The system includes an information collector and a coverage
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 communicating with both
the first wireless access network and the second wireless access
network. The information collector may further be configured to
obtain measurement information indicative of the signals measured
from the second wireless access network by the selected one or more
terminals and provide the measurement information to the coverage
estimator. 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 measurement 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 communication with
both the first and second wireless access networks" is intended to
cover not only wireless communication, but also include an indirect
communication path (e.g. wirelessly 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 network 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 information collector and
configured for storing the measurement information and/or a second
database connected to the coverage estimator and configured for
storing the coverage assessment.
In various embodiments, the first and second access wireless access
network respectively may for example include, respectively, a first
network using a first radio access technology and a second network
using a second radio access technology, a first network using a
first radio spectrum and a second network using a second radio
spectrum, a first network 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 base
stations, and the second wireless access network may include a
number of second base stations. In such an embodiment, 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 geographical 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 estimator 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 telecommunications
infrastructure as defined above are also disclosed.
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 terminals capable of measurement and
reporting across the different wireless access networks. The
cooperation refers to, among other things, the ability of
generating coverage assessment 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 complete and/or less costly coverage assessment may be
obtained, relative to the prior art approaches. Furthermore, the
disclosed 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 trigger
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 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 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
communicating with both the first and the second wireless access
networks.
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 determining their
locations).
When the location information is obtained from the terminals, 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 remainder 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 of terminals to be terminals in a specified
geographical area. For example, some or all 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 advantageous
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 providing
location information valid upon obtaining the measurement
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 measurement
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 information is obtained by the terminals. In case that
the location information is provided by the terminal itself, the
new location 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 different from the
old one, the new location may be used by updating 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 information 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 estimator. Such an
embodiment advantageously allows providing 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 network).
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 associated 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 terminals moved during the period between
obtaining the initial location information and actually performing
the measurements 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 database for future
use, but not used at the moment for the coverage assessment of the
second wireless access network.
In one embodiment, the information collector may be configured 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 measurement 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
coverage 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 coverage 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.
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;
FIG. 2 provides a schematic illustration of a telecommunications
infrastructure comprising two wireless access networks 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 generating 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 telecommunications
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 coverage areas 3A (solid lines) 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 reselection.
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. differ in 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 wireless 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 telecommunications
infrastructure 200 of FIG. 2 between the one or more OMCs and the
networks 2A and 2B of the corresponding 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 assessment system is not necessarily
implemented in such a centralized manner, but may also be
decentralised by implementing 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 estimator 8. The information
collector 7 is configured for collecting 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 configured for connecting to and receiving
information from the information collector 7 and, based on the
received information, generating the coverage assessment for the
second wireless access network 2B.
In the embodiment shown in FIG. 3, the information collector 7 is
included within an OMC 9A of the first wireless access network 2A
and the coverage estimator 8 is included within an OMC 9B 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 measurement
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 generating a
coverage assessment for one wireless access network in a
telecommunication infrastructure comprising two or more cooperating
wireless access networks using the coverage 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 invention. 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 wireless 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 operator who already has an UMTS network, the UMTS
network typically has a more extended coverage than the LTE
network, especially at the beginning of the LTE deployment. As
previously described, the terminals 5 are capable of communicating
with both the first and second wireless access networks 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 area. For example, some or
all 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 generating 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 assessment should be generated may be
selected for obtaining the measurement information, thus avoiding
collection of excessive 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 optimization 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 coverage of the second
wireless access network 2B.
The method then continues to step 420, where the information
collector 7 instructs the selected one or more terminals, 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 indications about cell identification, indications
about signal strength, indications about system information
provided by the measured cells, indications about timing,
indications about the moment a measurement has been made,
indications about the location or estimated location where a
measurement has been made, etc. The measurement information relates
at least to the LTE network and may additionally relate to
measurements in the UMTS network, for example in order to obtain an
LTE network signal strength measurement relative to a UMTS signal
strength measurement and/or to use either information to perform,
to support or to verify a location estimate. The measurement
information may be sent via RRC signalling to the UMTS network and
further via the Itf-N interface to the information collector 7.
Sometimes it may be possible that the location of the selected
terminals when they actually perform the measurements is different
from what it was when the initial location information was obtained
in the optional step prior to step 410. This could happen when the
selected terminals move during this period. Therefore, in one
embodiment, the information collector 7 may be configured to update
the location information for each of the selected one or more
terminals with the location information valid when the measurement
information was obtained from them. In case that the location
information is provided by the terminal itself, the terminal may
send the new location information along with the measurement
results via e.g. RRC channel of the UMTS network. In case that the
location of a particular selected terminal is estimated by the UMTS
network, the UMTS network may re-estimate the location when it
obtains the measurement results from that selected terminal. In any
case, if the new location is different from the old one, the new
location may be used by updating the old location information.
In another embodiment, the information collector 7 may be
configured to update the location information for each of the
selected one or more terminals after obtaining the measurement
information from them. In such an embodiment, if the new location
is different from the old one, an interpolation may be performed to
estimate the measurement location from the old and the new
locations.
Furthermore, if one of the selected terminals moved during the time
period between obtaining the initial location information (in the
optional step prior to step 410) and actually performing the
measurements as instructed by the information collector 7, and the
new location of such a terminal is out of the location area for
which the coverage assessment should be generated, the new location
and the corresponding measurement may be either discarded or stored
in the database 11A for future use, but not used at the moment for
the coverage assessment of the LTE network. In this case, the
information collector 7 may be further configured to update the
selected one or more terminals to eliminate terminals whose new
location is not included in a predefined location area for which
the coverage assessment should be generated.
The method then proceeds to step 440, where the information
collector 7 forwards the measurement information obtained from the
selected terminals to the coverage estimator 8 within the LTE
network. If the information collector 7 also has the location
information for the selected terminals, then the information
collector 7 may associate the received measurement information with
the location information prior to forwarding the measurement
information and the location information to the coverage estimator
8.
The coverage estimator 8 is in charge of the coverage estimation of
the LTE network (the second wireless access network 2B in this
example), with the measurement information and, optionally,
location information received from the information collector 7.
Once the coverage estimator 8 obtains the measurement information
(and, optionally, the location information) from the information
collector 7, then, in step 450, the coverage estimator 8 generates
the coverage assessment for the LTE network based on the
information obtained from the information collector 7. The coverage
assessment is generated by assembling a coverage map, representing
the geographic locations/pixels with associated signal strengths of
the LTE network. The coverage estimator 8 may also be configured to
instruct the information collector 7 with some specifications for
measurement, for example where to measure, when to measure, how
often to measure or which particular LTE cells to measure.
The measured results and corresponding location information may be
stored in the database 11A, and the estimated coverage results may
be stored in the database 11B, for future use. The historical data
in the database 11A may e.g. be used to make some statistical
processing of the measured signal strengths in the same
location/pixel or in a related set of locations/pixels. One example
of such statistical processing is to determine an average or median
value of the measured signal strengths in the considered
location(s)/pixel(s) in order to mitigate the effect of fading of
the LTE signal. Most advantageously, such statistical processing
may determine an estimate of the degree of fading in the considered
location(s)/pixel(s). It may determine, for example, an estimate
for the standard deviation and/or an estimate of a low and high
quantile value of the measured signal strengths in the considered
location(s)/pixel(s). Also, the low quantile value may be used as
an improved indicator of coverage in the considered
location(s)/pixel(s) compared to an indicator based on an average
or median value. Information about the severity of fading or
information about a low quantile of the predicted signal strength
is generally unavailable from coverage calculations based on models
for the attenuation of radio signals. The historical data in the
database 11B may e.g. be used to compare the coverage map before
and after deploying new base stations of the LTE network, to
confirm whether the coverage of the LTE network has improved or not
in some specific areas.
With some modifications, persons skilled in the art could extend
the deployment of the coverage assessment system to other
architectures, networks, and selection criteria than those
described in FIGS. 2-4.
Generating coverage assessment for one of the wireless access
networks using results of the measurements collected at one of the
other, cooperating, wireless access networks allows obtaining a
more accurate and complete coverage assessment, relative to the
prior art approaches. In addition, in contrast to the current
coverage estimation methods, the proposed approach is able to
account for the fact that a given wireless operator may operate
multiple wireless access networks with non-identical coverage area
(for example, one wireless access network may have an extensive,
possibly near-complete, coverage area, while another wireless
access network has a more limited, possibly discontinuous, coverage
area).
Based on the generated coverage assessment, the coverage estimator
8 may further be configured to suggest geographical areas as
candidates for coverage improvement. One or more of thus suggested
geographical areas may be selected as an input to a separate
planning procedure. The coverage estimator 8 may even further be
configured to indicate whether, e.g. based on an established
rule-of-thumb, the suggested area for improvement is sufficiently
close to an existing base station location to be served from there,
or that a new base station location needs to be found and, possibly
in addition, in which area such a base station location preferably
could be found. The coverage estimator 8 may be also configured to
compare the current coverage assessment with a previously generated
coverage assessment to determine whether the coverage optimization
actions in the past have led to a coverage improvement, identify
where the coverage improvement is most pronounced, and identify the
remaining areas where further coverage improvement is still needed.
The system and method for coverage assessment as described here can
also be advantageously used to measure interfering signals, e.g.
those generated by the second wireless access network. The measured
interference values may be taken into account for the coverage
assessment or be valued as such and taken into account as input to
a planning procedure.
One embodiment of the invention may be implemented as a program
product for use with a computer system. The program(s) of the
program product define functions of the embodiments (including the
methods described herein) and can be contained on a variety of
computer-readable storage media. Illustrative computer-readable
storage media include, but are not limited to: (i) non-writable
storage media (e.g., read-only memory devices within a computer
such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM
chips or any type of solid-state non-volatile semiconductor memory)
on which information is permanently stored; and (ii) writable
storage media (e.g., floppy disks within a diskette drive or
hard-disk drive or any type of solid-state random-access
semiconductor memory) on which alterable information is stored.
While the forgoing is directed to embodiments of the present
invention, other and further embodiments of the invention may be
devised without departing from the basic scope thereof Therefore,
the scope of the present invention is determined by the claims that
follow.
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