U.S. patent number RE45,311 [Application Number 13/753,888] was granted by the patent office on 2014-12-30 for reporting communication link information.
This patent grant is currently assigned to Intellectual Ventures I LLC. The grantee listed for this patent is Intellectual Ventures I LLC. Invention is credited to Juan Melero.
United States Patent |
RE45,311 |
Melero |
December 30, 2014 |
Reporting communication link information
Abstract
A method for reporting link information in a communication
system including a communication terminal and a plurality of
transceivers with each of which the communication terminal can
communicate over a respective communication link; the method
comprising: the communication terminal determining link information
for each of the communication links; and the communication terminal
periodically transmitting link messages, each link message
containing link information for a first set of the communication
links, and the link messages being formatted such that groups of
successive link messages collectively contain link information for
a larger set of the communication links.
Inventors: |
Melero; Juan (Malaga,
ES) |
Applicant: |
Name |
City |
State |
Country |
Type |
Intellectual Ventures I LLC |
Wilmington |
N/A |
DE |
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Assignee: |
Intellectual Ventures I LLC
(Wilmington, DE)
|
Family
ID: |
10861239 |
Appl.
No.: |
13/753,888 |
Filed: |
January 30, 2013 |
PCT
Filed: |
September 05, 2000 |
PCT No.: |
PCT/IB00/01316 |
371(c)(1),(2),(4) Date: |
August 27, 2002 |
PCT
Pub. No.: |
WO01/22765 |
PCT
Pub. Date: |
March 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11960930 |
Dec 20, 2007 |
Re. 40984 |
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Reissue of: |
10088238 |
Sep 5, 2000 |
6978120 |
Dec 20, 2005 |
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Reissue of: |
10088238 |
Sep 5, 2000 |
6978120 |
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Foreign Application Priority Data
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Sep 20, 1999 [GB] |
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9922204.4 |
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Current U.S.
Class: |
455/67.11;
455/63.1; 455/562.1; 455/450; 455/425; 455/522; 455/442; 455/452.1;
455/436; 455/67.13; 455/437; 455/62; 455/509 |
Current CPC
Class: |
H04W
48/16 (20130101); H04W 36/30 (20130101) |
Current International
Class: |
H04B
17/00 (20060101) |
Field of
Search: |
;455/67.11 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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197 42 650 |
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Apr 1999 |
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DE |
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19742650 |
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Apr 1999 |
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DE |
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9857512 |
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Dec 1998 |
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WO |
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Other References
Examination Report on European Patent Application 00 956 753.8,
dated Sep. 26, 2007. cited by applicant .
Final Office Action on U.S. Appl. No. 12/619,509, mailed Jun. 20,
2011. cited by applicant .
Final Office Action on U.S. Appl. No. 12/619,509, mailed Jun. 11,
2012. cited by applicant .
Final Office Action on U.S. Appl. No. 12/619,509, mailed Feb. 28,
2011. cited by applicant .
International Preliminary Examination Report for PCT/IB00/01316,
completed Feb. 1, 2002. cited by applicant .
International Search Report for PCT/IB00/01316, mailed Jan. 22,
2001. cited by applicant .
Non-Final Office Action on U.S. Appl. No. 11/305,839, mailed May
23, 2006. cited by applicant .
Non-Final Office Action on U.S. Appl. No. 12/619,509, mailed Nov.
29, 2010. cited by applicant .
Notice of Allowance on U.S. Appl. No. 12/619,509, mailed Oct. 1,
2012. cited by applicant .
Summons to Attend Oral Proceedings regarding European Patent
Application 00 956 753.8, dated Jun. 9, 2010. cited by applicant
.
Written Opinion on PCT/IB00/01316, mailed Aug. 29, 2001. cited by
applicant.
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Primary Examiner: Bilodeau; David
Parent Case Text
.Iadd.Notice: More than one reissue application has been filed for
the reissue of U.S. Pat. No. 6,978,120. The reissue applications
are the present application, U.S. patent application Ser. No.
12/619,509, filed Nov. 16, 2009, and U.S. patent application Ser.
No. 11/960,930, filed Dec. 20, 2007 (now U.S. Pat. No. Re. 40,984).
.Iaddend.
.Iadd.The present application is a reissue continuation of U.S.
Reissue patent application Ser. No. 12/619,509, filed Nov. 16,
2009, which is a reissue continuation of U.S. Reissue patent
application Ser. No. 11/960,930, filed Dec. 20, 2007 (now U.S. Pat.
No. Re. 40,984), which is a Reissue of U.S. Pat. No. 6,978,120
(previously U.S. patent application Ser. No. 10/088,238, filed Aug.
27, 2002), which is a National Stage entry of PCT/IB2000/001316,
filed Sep. 5, 2000, which claims priority to British Patent
Application No. 9922204, filed Sep. 20, 1999. U.S. Reissue patent
application Ser. No. 12/619,509, filed Nov. 16, 2009 is hereby
incorporated by reference in its entirety. .Iaddend.
Claims
What is claimed is:
.[.1. A method for reporting link information in a communication
system including a communication terminal and a plurality of
transceivers with each of which the communication terminal can
communicate over a respective communication link; the method
comprising: the communication terminal determining link information
for each of the communication links; and the communication terminal
periodically transmitting link message, each link message
containing link information for a first set of the communication
links, and the link messages being formatted such that groups of
successive link messages collectively contain link information for
a larger set of the communication links..].
.[.2. A method as claimed in claim 1, wherein link information for
at least one of the communication links is contained in each of
successive link messages..].
.[.3. A method as claimed in claimed 2, comprising the step of
determining a subset of the communication links having the best
link according to a selected measure, and wherein link information
for the communication links of that subset is contained in each of
successive link messages..].
.[.4. A method as claimed in claim 3, wherein the subset consists
of two communication links..].
.[.5. A method as claimed in claim 4, wherein periodically link
messages contain link information for the same ones of the
communication links..].
.[.6. A method as claimed in claim 2, wherein the communication
terminal is capable of transmitting the link information in a
plurality of schemes according to which link information is
distributed between successive link messages..].
.[.7. A method as claimed in claim 6, wherein the communication
system includes a control unit coupled to the transceivers, and the
method comprises the step of causing at least one of the
transceivers to transmit a scheme selection signal to the
communication terminal indicative of the one of the plurality of
schemes to be used by the communication terminal..].
.[.8. A method as claimed in claim 7, wherein the scheme selection
signal is transmitted on a broadcast channel..].
.[.9. A method as claimed in claim 7, wherein the scheme selection
signal is transmitted as part of a system information
message..].
.[.10. A method as claimed in claim 7, comprising the step of
operating the communication terminal in response to the scheme
selection signal so as to use the scheme indicated by the scheme
selection signal..].
.[.11. A method as claimed in claim 7, wherein one of the schemes
involves transmitting link information for a set of the
communication links in alternate link messages..].
.[.12. A method as claimed in claim 7, wherein one of the schemes
involves transmitting link information for a set of the
communication links in every third link message..].
.[.13. A method as claimed in claim 12, wherein the link messages
are transmitted over at least one of the said communication
links..].
.[.14. A method as claimed in claim 13, wherein each link message
is sent in a respective multiframe of communications over the said
communication links..].
.[.15. A method as claimed in claim 14, wherein each link message
contains link information of six of the communication links..].
.[.16. A method as claimed in claim 15, wherein the link
information for a communication link is indicative of the quality
of communications over that link..].
.[.17. A method as claimed in claim 16, comprising the steps of
receiving the link information and making a handover decision for
the communication terminal on the basis of the link
information..].
.[.18. A method as claimed in claim 17, comprising the step of the
communication terminal signaling that it is capable of operating so
as to transmit successive link messages containing link information
for different ones of the communication links..].
.[.19. A method as claimed in claim 18, wherein the step of the
communication terminal signaling that is capable of operating so as
to transmit successive link messages containing link information
for different ones of the communication links is performed on
establishments by the communication terminal of a connection with
the system..].
.[.20. A method as claimed in claim 19, wherein the communication
terminal is a radio telephone..].
.[.21. A method as claimed in claim 20, wherein each transceiver is
a base station transceiver of a radio telephone system..].
.[.22. A communication system comprising: a communication terminal;
a plurality of transceivers with each of which the communication
terminal can communicate over a respective communication link; the
communication terminal comprising link measurement means for
measuring link information for each of the communication links;
transmission means for periodically transmitting link messages,
each link message containing link information for a first set of
the communication links; and link message forming means for forming
the link messages such that groups of successive link messages
collectively contain link information for a larger set of the
communication links..].
.[.23. A communication terminal for operation in a radio
telecommunications system, the terminal comprising: communication
means for communicating with one or more of a plurality of radio
transceivers; measurement means for measuring a quality of signals
received from each of the said transceivers over a respective
communication link; and measurement message generation means for
generating measurement messages for transmission by the
communication means, each measurement message containing measured
quality information for a first set of the communication links; the
measurement message generation means being capable of generating a
series of measurements messages wherein groups of successive
measurement messages collectively contain measured quality
information for a larger set of the communication links..].
.[.24. A control unit for operating in a communication system, the
communication system including a communication terminal and a
plurality of transceivers with each of which the communication
terminal can communicate over a respective communication link, the
communication system being arranged to perform a method of
reporting link information comprising: the communication terminal
determining link information for each of the communication links;
and the communication terminal periodically transmitting link
messages, each link message containing link information for a first
set of the communication links, and the link messages being
formatted in accordance with a predetermined scheme such that
groups of successive link messages collectively contain link
information for a set of communication links larger than the first
set of communication links; the control unit being coupled to the
transceivers and being arranged to cause at least one of the
transceivers to transmit a scheme selection signal to the
communication terminal indicative of the one of the plurality of
schemes to be used by the communication terminal..].
.Iadd.25. A method for reporting link information in a
communication system, the method comprising: receiving, at a
network element, a first link message including first link
information about communication links corresponding to transceivers
in a first subset and second link information about communication
links corresponding to transceivers in a second subset; and
receiving, at the network element, a second link message including
the first link information about the communication links
corresponding to the transceivers in the first subset and third
link information about communication links corresponding to
transceivers in a third subset, and wherein the third link
information comprises an average of two or more link measurements;
wherein the communication links corresponding to the transceivers
in the first subset are better according to a predetermined measure
than the communication links corresponding to the transceivers not
in the first subset, and wherein a total number of transceivers in
the first subset is a first predetermined number, wherein a total
number of transceivers in the second subset is a second
predetermined number, and wherein the first subset and the second
subset have no transceivers in common, and wherein a total number
of transceivers in the third subset is the second predetermined
number, wherein the first subset and the third subset have no
transceivers in common, and wherein the second subset includes at
least one transceiver that is not in the third subset.
.Iaddend.
.Iadd.26. The method of claim 25, wherein a sum of the first
predetermined number and the second predetermined number is six.
.Iaddend.
.Iadd.27. The method of claim 25, wherein the first predetermined
number is four. .Iaddend.
.Iadd.28. The method of claim 25, wherein the predetermined measure
is received signal strength. .Iaddend.
.Iadd.29. The method of claim 25, wherein the predetermined measure
is bit error rate. .Iaddend.
.Iadd.30. The method of claim 25, wherein the predetermined measure
is frame error rate. .Iaddend.
.Iadd.31. The method of claim 25, wherein the average of the two or
more link measurements is an average of two link measurements.
.Iaddend.
.Iadd.32. The method of claim 25, wherein the average of the two or
more link measurements is an average of more than two link
measurements. .Iaddend.
.Iadd.33. A method for reporting link information in a
communication system, the method comprising: receiving, at a
network element, a number of link messages equal to a first number
of measurements of a first communication link, wherein each link
message from the number of link messages includes only one of the
first number of measurements, wherein all of the first number of
measurements are transmitted in the link messages, and wherein only
one link message from the number of link messages includes an
average of a second number of measurements; wherein the second
number is equal to a number of measurements of a second
communication link; wherein the link message that includes the
average of the second number of measurements also includes at least
one of the first number of measurements, wherein the first number
is greater than the second number, and wherein the second number is
greater than or equal to two; and facilitating, at the network
element, a handover decision based on the receiving link messages.
.Iaddend.
.Iadd.34. The method of claim 33, wherein the first number is four.
.Iaddend.
.Iadd.35. The method of claim 33, wherein the second number is two.
.Iaddend.
.Iadd.36. The method of claim 33, wherein the first number is four
and the second number is two. .Iaddend.
.Iadd.37. The method of claim 33, wherein each measurement of the
first communication link is better according to a predetermined
measure than each measurement of the second communication link.
.Iaddend.
.Iadd.38. The method of claim 37, wherein the predetermined measure
is received signal strength. .Iaddend.
.Iadd.39. The method of claim 37, wherein the predetermined measure
is bit error rate. .Iaddend.
.Iadd.40. The method of claim 37, wherein the predetermined measure
is frame error rate. .Iaddend.
.Iadd.41. A network element comprising: a receiver configured to
receive a measurement report from a communication terminal, wherein
the measurement report includes only one measurement chosen from a
first number of measurements of a first communication link and
further includes an average of a second number of measurements of a
second communication link, wherein the first number is greater than
the second number, and wherein the second number is greater than or
equal to two; and a processor configured to process the measurement
report to facilitate a handover decision. .Iaddend.
.Iadd.42. The network element of claim 41, wherein the second
number is two. .Iaddend.
.Iadd.43. The network element of claim 41, wherein each measurement
in the first number of measurements is better than each measurement
in the second number of measurements according to a predetermined
measure. .Iaddend.
.Iadd.44. The network element of claim 43, wherein the
predetermined measure is received signal strength. .Iaddend.
.Iadd.45. A network element comprising: a receiver configured to:
receive a first link message including first link information about
communication links corresponding to transceivers in a first subset
and second link information about communication links corresponding
to transceivers in a second subset; and receive a second link
message including the first link information about the
communication links corresponding to the transceivers in the first
subset and third link information about communication links
corresponding to transceivers in a third subset, and wherein the
third link information comprises an average of two or more link
measurements; wherein the communication links corresponding to the
transceivers in the first subset are better according to a
predetermined measure than the communication links corresponding to
the transceivers not in the first subset, and wherein a total
number of transceivers in the first subset is a first predetermined
number, wherein a total number of transceivers in the second subset
is a second predetermined number, and wherein the first subset and
the second subset have no transceivers in common, and wherein a
total number of transceivers in the third subset is the second
predetermined number, wherein the first subset and the third subset
have no transceivers in common, and wherein the second subset
includes at least one transceiver that is not in the third subset.
.Iaddend.
.Iadd.46. The network element of claim 45, wherein the second
number is two. .Iaddend.
.Iadd.47. The network element of claim 45, wherein the
predetermined measure is received signal strength. .Iaddend.
.Iadd.48. A non-transitory computer-readable medium storing
computer-executable instructions, the instructions comprising:
instructions to receive a first link message including first link
information about communication links corresponding to transceivers
in a first subset and second link information about communication
links corresponding to transceivers in a second subset; and
instructions to receive a second link message including the first
link information about the communication links corresponding to the
transceivers in the first subset and third link information about
communication links corresponding to transceivers in a third
subset, and wherein the third link information comprises an average
of two or more link measurements; wherein the communication links
corresponding to the transceivers in the first subset are better
according to a predetermined measure than the communication links
corresponding to the transceivers not in the first subset, and
wherein a total number of transceivers in the first subset is a
first predetermined number, wherein a total number of transceivers
in the second subset is a second predetermined number, and wherein
the first subset and the second subset have no transceivers in
common, and wherein a total number of transceivers in the third
subset is the second predetermined number, wherein the first subset
and the third subset have no transceivers in common, and wherein
the second subset includes at least one transceiver that is not in
the third subset. .Iaddend.
.Iadd.49. A non-transitory computer-readable medium storing
computer-executable instructions, the instructions comprising:
instructions to receive a number of link messages equal to a first
number of measurements of a first communication link, wherein each
link message from the number of link messages includes only one of
the first number of measurements, wherein all of the first number
of measurements are transmitted in the link messages, and wherein
only one link message from the number of link messages includes an
average of a second number of measurements; wherein the second
number is equal to a number of measurements of a second
communication link; wherein the link message that includes the
average of the second number of measurements also includes at least
one of the first number of measurements, wherein the first number
is greater than the second number, and wherein the second number is
greater than or equal to two; and instructions to facilitate a
handover decision based on the received link messages. .Iaddend.
Description
This invention relates to a method for reporting information on
communication links, for example link quality information, in a
telecommunications system such as a cellular radio
telecommunications network.
FIG. 1 shows schematically the configuration of a typical cellular
radio telecommunications network. The network comprises a number of
base-stations (BSs) 1, 2, 3 etc. Each base-station has a radio
transceiver capable of transmitting radio signals to and receiving
radio signals from the area of a cell 4, 5, 6 etc. next to the
base-station. By means of these signals the base-station can
communicate with a mobile station (MS) terminal 7 in that cell,
which itself includes a radio transceiver. Each base station is
connected to a mobile system controller (MSC) 8, which is linked in
turn to the public telephone network 9 and/or to other networks
such as packet data networks. By means of this system a user of the
MS 7 can establish a telephone call to the public network 9 via a
BS in whose cell the MS is located.
The location of the MS could be fixed (for example if it is
providing radio communications for a fixed building) or the MS
could be moveable (for example if it is a hand portable transceiver
or "mobile phone"). When the MS is moveable it may move between
cells of the cellular radio system. As it moves from one cell (the
"old cell") to another cell (the "new cell") there is a need to
hand it over from communication with the BS of the old cell to the
BS of the new cell without dropping the call due to a break in
communications between the mobile station and the network. This
process is known as handover. A need can also arise to hand over a
MS whose location is fixed, for example if atmospheric conditions
affect its communications with the old BS and call quality can be
improved by handing it over to another BS or if there is a need to
free up capacity of the old BS.
In some systems, for example the wideband code division multiple
access (W-CDMA) system proposed for the Universal Mobile Telephony
System (UMTS), a mobile station is capable of making traffic
communications with more than one base station at one time. This
macrodiversity arrangement allows greater reliability of
communications and can reduce the required transmission power. It
also means that handovers between one base station and another can
be performed in a gradual ("soft") rather than an abrupt ("hard")
way.
It is conventional for the system to include apparatus for
controlling handover and macrodiversity. That apparatus could be on
the network side (for example at the MSC) or the mobile side of the
air interface between the MS and a BS, or could be distributed
between the two. That apparatus conventionally receives information
relating to the quality of potential communications between the MS
and at least some of the BSs and optionally other information such
as data on the load on at least some of the BSs. Using this
information the apparatus determines which base station(s) an MS
should communicate with and issues instructions to the BSs and the
MS accordingly.
For the W-CDMA system it is proposed, in line with existing systems
such as GSM, that a mobile station will transmit to the network
measurement reports on communication quality with six nearby cells.
For example, according to the GSM standard a report on a nearby
("neighbouring") cell will occupy 17 reserved bits in a standard
reporting message of 107 bits. The reporting message can therefore
contain reports on only six nearby cells. Such reporting message is
to be sent by a mobile station in each multiframe--i.e. once every
480 ms.
The inventors of the present invention have identified that
especially in multisystem or multiband networks and/or in cellular
communication systems operating in a multilayer environment the
number of cells with which the mobile station may interact might
often be greater than six. It could therefore be advantageous for a
mobile station to be able to transmit measurement reports for more
than six cells. This would be especially advantageous in
multisystem or multiband networks and/or in cellular communication
systems operating in a multilayer environment. In general,
multimode systems can be defined as communication environments
where the mobile station may be in a service area where it can be
served by more than one serving network, system, standard,
frequency or the like. An example of a multiband system is a system
in which a dual-band mobile station can be served by GSM (Global
System for Mobile Communications) networks operating at 900 MHz and
1800 MHz. Another example is a system in which a mobile station can
be served by a GSM network and a UMTS/W-CDMA network, or a GSM
network and a DAMPS network.
It would thus be desirable for a mobile station to be able to
report on potential communications links with more than six cells.
One way in which this could be achieved is by lengthening the
reporting message to give room for measurement reports on more than
six cells. However, this would have major problems of
incompatibility with existing systems. Another possibility would be
for the level of reporting to be altered so as to occupy fewer than
17 bits. However, as well as problems of incompatibility with
existing systems, this solution would be expected to reduce the
reporting accuracy and therefore the precision of handover
decisions.
WO 98/57512 discloses an arrangement where a measurement report is
transferred to a network during the first available slow associated
control channel periods. The measurement report contains data that
the mobile terminal obtained while it was waiting in the idle mode.
During subsequent slow associated control channel periods, the
mobile terminal transfers measurement information to the network
based on the data obtained in the active mode.
There is therefore a need for a practical method whereby a mobile
station can transmit reporting messages on links with an increased
number of cells. Such a method should preferably be capable of
retaining a degree of consistency with existing standards and
standardisation proposals. By this means, the method may preferably
enhance multisystem, multiband and/or multimode operation. It is
one aim of the present invention to at least partially address one
or more of the above issues.
According to one aspect of the present invention there is provided
a method for reporting link information in a communication system
including a communication comprising, the communication terminal
determining link information for each of the communication links,
and the communication terminal periodically transmitting link
messages, each link message containing link information for a first
set of communication links, and the link messages being formatted
in accordance with a predetermined scheme such that groups of
successive link messages collectively contain link information for
a set of communication links larger than the first set of
communication links.
The said larger set is suitably larger than the first set of the
communication links. The method preferably includes the step of
defining the said larger set, for example by selecting
communication links to form the said larger set.
Preferably link information for at least one of the communication
links is contained in each of successive link messages. For
instance, each successive link message may contain link information
for one, two or more of the communication links, whilst link
information for others of the communication links is not contained
in every link message. That latter link information may be sent in
link messages spaced apart by a set amount, for example every two
or three link messages, or as determined by a less strict periodic
or a periodic scheme.
It is thus preferred that successive link messages contain link
information for at least one communication link in common. It is
also preferred that link messages spaced apart by a set
interval--for example by one, two or three other
messages--regularly contain link information for the same ones of
the communication links.
The method may comprise the step of determining a subset of the
communication links having the best link according to a selected
measure, and wherein link information for the communication links
of that subset is contained in each of successive link messages.
The subset preferably consists of one communication link, or
alternatively of two communication links.
It is preferred that periodically link messages contain link
information for the same ones of the communication links.
The communication terminal is preferably capable of transmitting
the link information in a plurality of schemes according to which
link information is distributed between successive link messages.
Such schemes may involve transmitting link information for a set of
the communication links in alternate link messages, or in every
third link message.
The communication system suitably includes a control unit (e.g. an
MSC or the like) coupled to the transceivers. The method suitably
comprises the step of causing at least one of the transceivers to
transmit a scheme selection signal to the communication terminal
indicative of the one of the plurality of schemes to be used by the
communication terminal. The scheme selection signal may be
transmitted on a broadcast channel. The scheme selection signal may
be transmitted as part of a system information message. The method
may suitably comprise the step of operating the communication
terminal in response to the scheme selection signal so as to use
the scheme indicated by the scheme selection signal.
The link messages may be transmitted over at least one of the said
communication links. The link messages may be each sent in a
respective multiframe. (The multiframe may be defined by reference
to normal communications over the said communication links).
Each link message preferably contains link information for six of
the communication links, and most preferably for only six of the
communication links.
The link information for a communication link is preferably in some
way indicative of the quality of communications over that link. The
link information may, for example be indicative of received signal
strength information for communications over the link--for example
of the strength of received broadcast signals over the link.
The method may suitably comprise the steps of receiving the link
information and making a handover decision for the communication
terminal on the basis of the link information. That decision may be
made at an MSC or like equipment.
The method may comprise the step of the communication terminal
signalling that it is capable of operating so as to transmit
successive link messages containing link information for different
ones of the communication links. That signalling may be performed
on establishment by the communication terminal of a connection with
the system.
According to the present invention from a second aspect there is
provided a communication system comprising a communication
terminal, a plurality of transceivers with each of which the
communication terminal can communicate over a respective
communication link; a communication terminal comprising link
measurement means for measuring link information for each of the
communication links, transmission means for periodically
transmitting link messages, each link message containing link
information for a first set of communication links, link message
forming means for forming the link messages in accordance with a
predetermined scheme such that groups of successive link messages
collectively contain link information for a set of communication
links larger than the first set of communication links.
According to the present invention, third aspect there is provided
a communication terminal for operation in a radio
telecommunications system the terminal comprising communication
means for communicating with one or more of a plurality of radio
transceivers, measurement means for measuring a quality of signals
received from each of the said transceivers over respective
communication link, and measurement message generation means for
generating measurement messages for transmission by the
communication means, each measurement message containing measured
quality information for a first set of the communication links, the
measurement message generation means being capable of generating a
series of measurement messages in accordance with a predetermined
scheme, wherein groups of successive measurement messages
collectively contain measured quality information for a set of
communication links larger than the first set of communication
links.
Optional additional features of the second and third aspects of the
present invention include features analogous to those set out above
in relation to the first aspect of the present invention.
The communication terminal may be a radio and/or cellular
telephone. Each transceiver may be a base station transceiver of a
radio telephone system. The communication system may suitably be a
cellular telephone network. The communication terminal may suitably
be capable of communicating by radio with one or more, and
preferably all, of the transceivers.
The present invention will now be described by way of example with
reference to the accompanying drawings, in which:
FIG. 1 shows schematically the configuration of a typical cellular
radio telecommunications network;
FIG. 2 shows a schematic diagram of some components of a mobile
station; and
FIG. 3 illustrates signal flow in a measurement reporting
arrangement.
The present reporting method and associated apparatus will be
described below with general reference to the GSM system and to the
proposed UMTS/W-CDMA standard, but it will be understood that the
method is analogously applicable to provide enhanced reporting in
other telecommunications systems.
The present reporting method involves increasing the number of
cells on which measurement reports may be sent by reducing the
frequency with which reports are sent on nearby ("neighbouring")
cells. Thus, successive measurement report messages may include
measurement data for different sets of nearby cells. In other
words, measurement reports on neighbouring cells may be transmitted
with different frequencies. Such frequencies may be the same or
different. In a preferred arrangement, the mobile station
determines a set of neighbours providing the best links to it;
measurement reports are then sent for those cells in every report
message, whereas information on other links is sent less
frequently--for example in every second or third report
message.
To avoid ambiguity, it should be noted that the term "neighbouring"
is generally used to refer to any further cell that can be reached
by a mobile station in a cell of the cellular communication system,
without such a cell having to actually border any cell with which
the mobile station is currently communicating. Thus "neighbouring"
cells will typically be wholly or partly overlapping. Neighbouring
cells may be cells of another communication network or cells of
another frequency. This is the case when, for example, dual-band
mobile stations are used.
FIG. 1 which shows a cellular network. It should be appreciated
that although FIG. 1 shows base stations which each provide an
omnidirectional cell, embodiments of the present invention may be
implemented using any appropriate configuration of cells. It is
also noted that the radio coverage area defining a cell may consist
of a sector of a base station provided with a directional or sector
antenna (not shown in FIG. 1). Such a sector base station may use
e.g. three 120.degree. directional antennas whereby three radio
coverage areas are provided, or four 90.degree. directional
antennas providing four radio coverage areas and so on, or any
combinations of different radio coverage beam widths. It should
also be appreciated that base stations may sometimes be referred to
as node B (e.g. in the UMTS standard). For simplicity it will be
assumed herein that each cell is associated with a single base
station transceiver unit (BTS).
In FIG. 1 each radio coverage area or cell is served by the
respective base transceiver station BTS 1, 2, 3 etc. Each base
transceiver station BTS is arranged to transmit signals to and
receive signals from the mobile station MS 7 in the cell. Likewise,
the mobile station is able to transmit signals to and receive
signals from a respective base transceiver station. The mobile
station 7 accomplishes this via wireless (preferably radio)
communication with the base stations. Typically a number of mobile
stations will be in communication with each base station although
only one mobile station is shown in FIG. 1 for clarity.
Each of the base stations is connected to a network controller,
which in one form of the exemplifying GSM system comprises a base
station controller (BSC) 10 connected further to a Mobile Switching
Centre (MSC) 9. In the described embodiment the MSC is used as a
network controller. In some arrangements the base station
controller 10 controlling one or several base stations between the
network controller and the base stations may be omitted. The
network controller controls its service area, i.e. the cells and
base stations connected to it, either directly or via the base
station controller. It is noted that typically more than one
network controller is provided in a network. The network controller
is connected to other elements or parts of the telecommunications
network system via a suitable linking or gateway apparatus, such as
Gateway Mobile Switching Centre (GMSC; not shown).
The implementation of the basic communication formatting between
the mobile station, the base station and the controller in GSM and
UMTS/W-CDMA systems is known, and will thus not be discussed in
more detail herein. It is sufficient to note that the interface may
comprise channels in both uplink and downlink directions between
the mobile station in the cell associated with a given base station
and that the information sent to the mobile station and the data
may be sent in any suitable format. The messages sent from the
mobile stations may include information identifying the mobile
station (for instance, MS ID and/or IMSI (Mobile Station Identity
and/or International Mobile Subscriber Identity,
respectively)).
As also illustrated in FIG. 1, the mobile station can be
simultaneously in the signalling or coverage area of several cells
and their associated base stations. The mobile station is arranged
to perform measurements in order to be able to provide information
based on which a suitable cell can be selected for serving the
mobile station. In other words, in addition to controlling the
ongoing connection with the servicing base station, the mobile
station performs measurements concerning the neighbouring cells as
well. These measurements may be of any appropriate feature that is
in some way indicative of the quality of potential traffic
communications over the link between the mobile station and that
cell; examples are signal strength of the base station for the cell
as received at the mobile station, error rate of communications
from that base station (e.g. bit error rate or frame error rate),
or delay or distortion of such communications.
FIG. 2 shows in more detail a mobile station capable of operation
in the system of FIG. 1. The mobile station, which in this case is
a cellular telephone, includes a radio transceiver unit 20, a
measurement unit 21 and a control unit 22. These may be implemented
as distinct units as illustrated in FIG. 2 or by software running
on common hardware.
The transceiver 20 transmits traffic signals to and receives
traffic signals from one or more base stations to which the mobile
station is currently attached. The transmissions to and from the
mobile station are split into multiframes, each of which occupies
480 ms. The transceiver also receives signals from other base
stations, typically signals on one or more broadcast channels e.g.
BCCH. These signals as well as signals received from the base
station(s) to which the mobile station is attached are directed to
the measurement unit 21. The measurement unit measures a feature of
those signals as mentioned above--for example received signal
strength. The measurement results are passed to the control unit 22
which generates measurement reports according to a scheme that will
be described below. The measurement reports are then transmitted to
the base station(s) to which the mobile station is attached. The
measurement reports are then used by the network to make handover
decisions.
The measurement reports themselves are suitably of a known format,
for example of 107 bits including 17 bits per cell/base station
that is being reported on.
The scheme used by the control unit may be one of a number of
schemes, example schemes being described below.
Reporting Scheme 0
For reasons of backwards compatibility the control unit is capable
of transmitting measurement reports in which each successive
measurement report includes measurement information for
communication links with the six cells determined by the control
unit to be the best (e.g. being received most strongly or with
fewest errors). Thus it will normally be the case that successive
messages will include data relating to the same six cells.
Reporting Scheme 1
The measurement unit measures data for links with up to 10
neighbouring cells. These cells will be termed N1 to N10. The two
best cells are selected by the control unit. These are, for
example, the two that are received with the highest signal level.
Measurement data for these cells (N1 and N2, say) is sent in every
multiframe (MF)--that is every 480 ms. Measurement data for each of
the remaining 8 neighbours (N3-N10) is distributed between
successive multiframes so as to be sent every second
multiframe--that is every 960 ms
The structure of successive measurement reports under this system,
with each measurement report including slots for data on
measurements of six cell links, is shown in the following
table:
TABLE-US-00001 Measurement Report Multiframe Multiframe Multiframe
Slot Number n n + 1 n + 2 . . . 1 N1 N1 N1 . . . 2 N2 N2 N2 . . . 3
N3 N4 N3 . . . 4 NS N6 N5 . . . 5 N7 N8 N7 . . . 6 N9 N10 N9 . .
.
The values reported for the neighbours N3-N10 could be an averaged
value of measurements over the appropriate two multiframe period
before which they are sent, so little or no information is lost.
Alternatively the first, second, higher or lower value measured for
each of neighbours N3-N10 over the period could be sent.
Reporting Scheme 2
The measurement unit measures data for links with up to 15
neighbouring cells. These cells will be termed N1 to N15. The best
neighbour (N1) is identified and a report transmitted for it every
480 ms. The 2nd to 7th best neighbours (N2-N7) are identified and a
report transmitted for each of them every 960 ms. The remaining 8
neighbours (N8-N15) are reported on every 1920 ms.
The structure of successive measurement reports under this system,
with each measurement report including slots for data on
measurements of six cell links, is shown in the following
table:
TABLE-US-00002 Measurement Report Slot Number MF n MF n + 1 MF n +
2 MF n + 3 MF n + 4 . . . 1 N1 N1 N1 N1 N1 . . . 2 N2 N3 N2 N3 N2 .
. . 3 N4 N5 N4 N5 N4 . . . 4 N6 N7 N6 N7 N6 . . . 5 N8 N9 N10 N11
N8 . . . 6 N12 N13 N14 N15 N12 . . .
Note that the value reported for the neighbours N2-N7 could be an
averaged value over the two multiframes between reports on them,
and the value reported for N8-N15 could be an average over the four
multiframe periods between reports on them, so little or no
information may be lost. Alternatively, one of the other selection
procedures described above could be used.
Reporting Scheme 3
In this scheme the control unit 22 of the mobile station ranks
(e.g. on the basis of received signal level) the quality of the
links with neighbouring base stations. The reporting rate for each
neighbour is determined by its ranking.
In a first approach the mobile can re-evaluate the ranking of the
neighbours and therefore their reporting rate each 2.sup.nd
multiframe (960 ms). In order to do so the averaged value of the
signal level over the previous 2 multiframes can be used.
There would be two options to perform such averaging: 1. The mobile
stores all the individual values determined over the 2 multiframes.
In the worst case this would require it to store 2 received signal
level (RxLev) values (of conventionally 6 bits each), for example
for a maximum of, say, 15 neighbours. This would requires a total
of 180 bits of memory 23 in the control unit 22 of the mobile. 2.
Ongoing averaging. The averaging can be an ongoing averaging in
order to minimise the required memory. If this approach is used
selected the memory required in the mobile would be only 90 bits.
Example:
TABLE-US-00003 Multiframe 1 2 RxLev 30 45 Average 30 37.5
Alternatively, the mobile could re-evaluate the ranking of the
neighbours and therefore their reporting rate each 4.sup.th
multiframe (1920 ms). In order to do so the averaged value of the
signal level over the previous 4 multiframes could be used.
In order to do so there would be two options: 1. The mobile stores
all the values measured over the 4 multiframes. In the worst case
this would require to store 4 RxLev values (6 bits each) for a
maximum of, say, 15 neighbours. This requires a total of 45 bytes
of memory in the mobile. 2. Ongoing averaging. The averaging can be
an ongoing averaging in order to minimise the required memory. If
this approach was selected the memory required in the mobiles would
be only 90 bits. Example:
TABLE-US-00004 Multiframe 1 2 3 4 RxLev 30 45 33 60 Average 30 37.5
36 42
This scheme provides an extremely flexible way for the mobile
station to send measurement information from more cells to the
network.
The schemes 1 to 3 described above provide the facility to transmit
measurement reports on links with neighbouring cells at different
rates depending on their signal level ranking.
The mobile station may automatically select an appropriate
reporting scheme, or the network may indicate to the mobile station
which reporting scheme is to be used. In the latter case, the
indication may be by means of a scheme indication signal, which
could be sent over a broadcast channel, for example the BCCH, and
for example as part of the BCCH System Information message. This
would allow network operators to control the introduction and
operation of the enhanced reporting schemes described above. The
use of two bits forming the scheme indication signal would allow
the implementation of 4 different reporting modes. FIG. 3
illustrates the signal flow in such an implementation.
Preferably, mobiles that are able to offer the enhanced reporting
schemes 1 to 3 described above should signal the availability of
such schemes to the network. This may, for example be done each
time they establish a connection to the network. At that time the
mobiles supporting the above functionality may preferably inform
the network that they are "alternative neighbour reporting
compliant", so the network knows the available formats of neighbour
reporting for a connection with those mobiles.
The selection of the relevant cells for reporting may be based on
any appropriate predefined rule of selection. The rules may be
defined in the standards the mobile station and/or the
communication system are arranged to use. The rules may be stored
permanently in the mobile station. According to one possibility the
rules are stored in an appropriate network element and transmitted
therefrom to the mobile station when ever required. The rules for
selecting relevant cells may also be changed when this is deemed
necessary. The selection of the relevant cells may be based, with
no limitation to the following, on the measured signalling levels,
used radio frequencies, direction of the movement of the mobile
station, loading conditions of the neighbouring cells and so
on.
In some of the schemes described above it is possible that
resolution of neighbour cell measurement information could be lost
due to the increased period between transmissions of some neighbour
data. This can be mitigated or even overcome by means of
pre-averaging averaging of individual measured values by the
control unit 22 of the mobile station. If the mobile performs
pre-averaging of the raw information that is collected by the
measurement unit 21, then no information would be lost as the
reported values for those neighbours with slower reporting rate
will contain the averaged value of all the available information.
Many networks are, in any event, configured to average the
neighbour values reported by mobiles. In the system described
above, since the network should know the reporting method used by
each connection with a mobile and should know the reporting rate of
each reported neighbour, it could apply a different averaging to
each neighbour. Therefore, from a system perspective the
performance of the standard and the alternate reporting methods
could be enhanced, as the result after the averaging is the same,
but the number of neighbours available to the system could be
dramatically increased.
The period between measurement report messages is, of course,
system-dependant and could be greater or less than 480 ms.
In view of the foregoing description it will be evident to a person
skilled in the art that various modifications may be made within
the scope of the invention as defined by the accompanying
claims.
* * * * *