DESCRIPTION
Title of Invention
COMMUNICATION SYSTEM WITH EXTENSION CARRIER
Technical Field
The present invention relates to mobile communications devices and networks,
particularly but not exclusively those operating according to the 3rd Generation Partnership
Project (3GPP) standards or equivalents or derivatives thereof. The invention has particular
although not exclusive relevance to the Long Term Evolution (LTE) of UTRAN (called Evolved
Universal Terrestrial Radio Access Network (E-UTRAN)).
Background Art
It has been decided, as part of the 3GPP standardisation process, that downlink operation
for system bandwidths beyond 20MHz will be based on the aggregation of a plurality of
component carriers at different frequencies. Such carrier aggregation can be used to support
operation in a system both with and without a contiguous spectrum (for example, a non
contiguous system may comprise component carriers at 800MHz, 2GHz, and 3.5GHz). Whilst a
legacy mobile device may only be able to communicate using a single, backward compatible,
component carrier, a more advanced multi-carrier capable terminal would be able to
simultaneously use the multiple component carriers.
Carrier aggregation can be particularly beneficial in a heterogeneous network (HetNet),
even when the system bandwidth is contiguous, and does not exceed 20 MHz because multiple
carriers enable interference management between different power class cells as well as open
access and closed subscriber group (CSG) cells. Long-term resource partitioning can be carried
out by exclusively dedicating carriers to a certain power class of cell (Macro/Pico/CSG).
Further, the need for interference management between different cells operating on
component carriers of the same frequency in co-incident or overlapping geographic areas has led
to the development of extension carriers (which are not backwards compatible with legacy
devices). Extension carriers may be used as a tool for carrier aggregation based HetNet
operation and improved spectral efficiency. A multi-carrier capable base station is able to
operate at least one of its carriers as an extension carrier, on which a control channel (e.g. a
channel carrying resource scheduling information such as the Physical Downlink Control
Channel (PDCCH)), a Common reference Signal (CRS) (sometimes referred to as a Cell-specific
Reference Signal), and other information cannot be transmitted. To all<
extension carrier, at least one further component carrier of the component carrier set used by the
multi-carrier base station must be a stand-alone carrier that can be used to transmit the
scheduling information for the extension carrier.
Accordingly, when a first base station is operating a component carrier as an extension
carrier, another base station may operate a component carrier of the same frequency to transmit a
control channel, a CRS and other such information more reliably, in the same general geographic
area as the first base station, without significant interference because there is no corresponding
control channel, CRS and other such information on the extension carrier operated by the first
base station.
In more detail, an extension carrier comprises a carrier that cannot be operated as a single
carrier (stand-alone) carrier, but must be a part of a component carrier set where at least one of
the carriers in the set is a stand-alone-capable carrier. An extension carrier may not be used for
transmission of any of the following:
· a Physical Downlink Control Channel (PDCCH);
• a Physical Hybrid ARQ Indicator Channel (PHICH);
• a Physical Control Format Indicator Channel (PCFICH);
• a Physical Broadcast Channel (PBCH);
a Primary Synchronization Signal (PSS);
· a Secondary Synchronization Signal SSS; or
• a Common Reference Signal Cell-specific Reference Signal (CRS).
Disclosure of the Invention
Problems to be solved by the Invention
Thus, a base station may operate a primary cell on a first component carrier and a
secondary cell on a second component carrier operating as an extension carrier. When a mobile
communication device enters the cell of the base station, the base station is able to provide
configuration information to the mobile device identifying the radio resource configuration for
the primary and secondary cells.
It is possible, however, that the geographical areas covered by the primary cell and
secondary cell may not b e coincident - either by design, or because the range of the first and
second component carriers is different as a result of radio environment conditions. Accordingly,
a mobile communication device may enter, communicate from, and then leave the primary cell
without ever entering the secondary cell. In such cases the base station may, undesirably, signal
the mobile communication device to add the secondary cell configuratii
the secondary cell configuration) when the mobile communication device is not within sufficient
range of the extension carrier for it to be used as a secondary cell.
The invention therefore aims to provide a mobile communication system, a mobile
communication device, a communication node and associated methods which overcomes or at
least mitigates the above issues.
Means to solve the Problems
According to one aspect of the invention there is provided communication apparatus for a
cellular communication system, the communication apparatus comprising: means for operating a
first cell using a first component carrier and a second cell using a second component carrier,
wherein: reference signals of a first type are provided in a control region and in a data region of
sub-frames communicated using the first component carrier; the reference signals of the first
type are not provided in sub-frames communicated using the second component carrier; and
reference signals of a second type are provided in a data region but are not provided in a control
region of sub-frames communicated using the second component carrier; means for
communicating with a mobile communication device using the first component carrier; means
for communicating with the mobile communication device using the second component carrier;
means for receiving, from the mobile communication device, results of measurements performed
on the reference signals of the first type for the first component carrier and results of
measurements performed on the reference signals of the second type for the second component
carrier; means for determining, from the results of the measurements performed on the reference
signals of the second type, whether or not said mobile communication device is within an area
covered by said second cell; and means for transmitting to the mobile communication device, in
dependence on whether or not said mobile communication device is within an area covered by
said second cell, information for allowing said mobile communication device to communicate
using said second component carrier in said second cell.
According to one aspect of the invention there is provided a mobile communication
device for communicating with communication apparatus of a cellular communication system,
which communication apparatus is configured to operate a first cell using a first component
carrier and a second cell using a second component carrier, wherein: reference signals of a first
type are provided in a control region and in a data region of sub-frames communicated using the
first component carrier; the reference signals of the first type are not provided in sub-frames
communicated using the second component carrier; and reference signals of a second type are
provided in a data region but are not provided in a control region of sub-frames communicated
using the second component carrier; and wherein the mobile communic
means for communicating with the communication apparatus using the first component carrier;
means for communicating with the communication apparatus using the second component
carrier; means for performing measurements on the reference signals of the first type for the first
component carrier for use in determining a signal strength of the first component carrier, and for
performing measurements on the reference signals of the second type for the second component
carrier for use in determining a signal strength of the second component carrier; means for
reporting, to the communication apparatus, results of the measurements performed; and means
for receiving, from said communication apparatus, information for allowing said mobile
communication device to communicate using said second component carrier in said second cell
in the event that the results of measurements of the reference signals of the second type for the
second component carrier indicate that said mobile communication device is within an area
covered by said second cell.
According to one aspect of the invention there is provided communication apparatus for a
cellular communication system, the communication apparatus comprising: means for operating a
first cell using a first component carrier and a second cell using a second component carrier,
wherein a control channel and reference signals of a first type are provided using the first
component carrier, and wherein the control channel and the reference signals of the first type are
not provided, and reference signals of a second type are provided, using the second component
carrier; means for communicating with a mobile communication device using the first
component carrier; means for communicating with the mobile communication device using the
second component carrier; means for receiving, from the mobile communication device, results
of measurements performed on the reference signals of the first type for the first component
carrier and results of measurements performed on the reference signals of the second type for the
second component carrier; means for determining, from the results of the measurements
performed on the reference signals of the second type, whether or not said mobile
communication device is within an area covered by said second cell; and means for transmitting
to the mobile communication device, in dependence on whether or not said mobile
communication device is within an area covered by said second cell, information for allowing
said mobile communication device to communicate using said second component carrier in said
second cell.
The reference signals of the first type may be provided in a control region and in a data
region of sub-frames communicated using the first component carrier; and the reference signals
of the second type may be provided in a data region and may not be provided in a control region
of sub-frames communicated using the second component carrier.
The communication apparatus may further comprise means for providing measurement
configuration information to the mobile communication device for configuring said mobile
communication device to perform said measurements on the reference signals of the second type.
The determining means may be operable to determine a reference signal received power
'RSRP' for the second component carrier from said received results of measurements performed
on the reference signals of the second type.
The determining means may be operable to determine a reference signal received quality
'RSRQ' for the second component carrier from said received results of measurements performed
on the reference signals of the second type.
The communication apparatus may comprises at least one of a serving mobile location
centre 'SMLC and a base station.
According to one aspect of the invention there is provided a mobile communication
device for communicating with communication apparatus of a cellular communication system,
which communication apparatus is configured to operate a first cell using a first component
carrier and a second cell using a second component carrier, wherein a control channel and
reference signals of a first type are provided using the first component carrier, wherein the
control channel and the reference signals of the first type are not provided, and reference signals
of a second type are provided using the second component carrier, and wherein: the mobile
communication device comprises: means for communicating with the communication apparatus
using the first component carrier; means for communicating with the communication apparatus
using the second component carrier; means for performing measurements on the reference
signals of the first type for the first component carrier, for use in determining a sigiial strength of
the first component carrier and for performing measurements on the reference signals of the
second type for the second component carrier, for use in determining a signal strength of the
second component carrier; means for reporting, to the communication apparatus, results of the
measurements performed; and means for receiving, from said communication apparatus,
information for allowing said mobile communication device to communicate using said second
component carrier in said second cell in the event that the results of measurements of the
reference signals of the second type for the second component carrier, indicate that said mobile
communication device is within an area covered by said second cell.
The reference signals of the first type may be provided in a control region and in a data
region of sub-frames communicated using the first component carrier; and the reference signals
of the second type may be provided in a data region and may not be provided in a control region
of sub-frames communicated using the second component carrier.
A mobile communication device according to any of claims 2 or 9 to 0 wherein said
measurement means is operable to determine a reference signal received power 'RSRP' for the
second component carrier from said reference signal of the second type.
A mobile communication device according to any of claims 2 or 9 to 1 wherein said
measurement means is operable to determine a reference signal received quality 'RSRQ' for the
second component carrier from said reference signal of the second type.
A mobile communication device according to any of claims 2 or 9 to 1 wherein said
measurement means is operable to determine at least one of a rank indicator (RI), precoding
matrix indicator (PMI) and a channel quality indicator (CQI) from said reference signal of the
second type.
A mobile communication device according to any of claims 2 or 9 to 13 further
comprising means for receiving measurement configuration information from the
communication apparatus, and means for configuring said mobile communication device to
perform said measurements on the reference signals of the second type.
The reference signals of the second type may comprise positioning reference signals
'PRS' and/or may comprise channel state information reference signals 'CSI-RS'. The reference
signals of the second type may comprise common reference signals 'CRS' (also known as Cellspecific
reference signals 'CRS').
The second component carrier may comprise an extension carrier.
The first carrier may comprise a stand alone carrier.
The control region of the sub-frames may comprise a region normally reserved for a
physical downlink control channel 'PDCCH'.
The information for allowing said mobile communication device to communicate using
said second component carrier in said second cell may comprise secondary cell configuration
information.
The information for allowing said mobile communication device to communicate using
said second component carrier in said second cell may comprise an indication to activate said
secondary cell at said mobile communication device.
According to one aspect of the invention there is provided a communication system
comprising at least one communication apparatus as described above and at least one mobile
communication device as described above.
According to one aspect of the invention there is provided a computer program product
comprising instructions operable to program a programmable processor to implement
communication apparatus as described or a mobile communication devi
According to one aspect of the invention there is provided a method preformed by
communication apparatus for a cellular communication system, the method comprising:
operating a first cell using a first component carrier and a second cell using a second component
carrier, wherein a control channel and reference signals of a first type are provided using the first
component carrier, and wherein the control channel and the reference signals of the first type are
not provided, and reference signals of a second type are provided, using the second component
carrier; communicating with a mobile communication device using the first component carrier;
receiving, from the mobile communication device, results of measurements performed on the
reference signals of the first type for the first component carrier and results of measurements
performed on the reference signals of the second type for the second component carrier;
determining, from the results of the measurements performed on the reference signals of the
second type, whether or not said mobile communication device is within an area covered by said
second cell; and transmitting to the mobile communication device, in dependence on whether or
not said mobile communication device is within an area covered by said second cell, information
for allowing said mobile communication device to communicate using said second component
carrier in said second cell.
According to one aspect of the invention there is provided a method preformed by a
mobile communication device for communicating with communication apparatus of a cellular
communication system, which communication apparatus is configured to operate a first cell
using a first component carrier and a second cell using a second component carrier, wherein a
control channel and reference signals of a first type are provided using the first component
carrier, wherein the control channel and the reference signals of the first type are not provided,
and reference signals of a second type are provided using the second component carrier, and
wherein: the method comprises: communicating with the communication apparatus using the
first component carrier; performing measurements on the reference signals of the first type for
the first component carrier, for use in determining a signal strength of the first component
carrier; performing measurements on the reference signals of the second type for the second
component carrier, for use in determining a signal strength of the second component carrier;
reporting, to the communication apparatus, results of the measurements performed; and receiving,
from said communication apparatus, information for allowing said mobile communication device
to communicate using said second component carrier in said second cell in the event that the
results of measurements of the reference signals of the second type for the second component
carrier, indicate that said mobile communication device is within an area covered by said second
cell.
The reference signals of the first type may be provided in a control region and in a data
region of sub-frames communicated using the first component carrier; and the reference signals
of the second type may be provided in a data region and may not be provided in a control region
of sub-frames communicated using the second component carrier.
According to one aspect of the invention there is provided a computer program product
comprising instructions to perform a method as recited above.
According to one aspect of the invention there is provided communication apparatus for a
cellular communication system, the communication apparatus comprising: a controller operable
to operate a first cell using a first component carrier and a second cell using a second component
carrier, wherein a control channel and reference signals of a first type are provided using the first
component carrier, and wherein the control channel and the reference signals of the first type are
not provided, and reference signals of a second type are provided, using the second component
carrier; a communications module operable to communicate with a mobile communication
device using the first component carrier; a communications module operable to communicate
with the mobile communication device using the second component carrier; a receiver module
operable to receive, from the mobile communication device, results of measurements performed
on the reference signals of the first type for the first component carrier and results of
measurements performed on the reference signals of the second type for the second component
carrier; a determiner operable to determine, from the results of the measurements performed on
the reference signals of the second type, whether or not said mobile communication device is
within an area covered by said second cell; and means for transmitting to the mobile
communication device, in dependence on whether or not said mobile communication device is
within an area covered by said second cell, information for allowing said mobile communication
device to communicate using said second component carrier in said second cell.
According to one aspect of the invention there is provided a mobile communication
device for communicating with communication apparatus of a cellular communication system,
which communication apparatus is configured to operate a first cell using a first component
carrier and a second cell using a second component carrier, wherein a control channel and
reference signals of a first type are provided using the first component carrier, wherein the
control channel and the reference signals of the first type are not provided, and reference signals
of a second type are provided using the second component carrier, and wherein: the mobile
communication device comprises: a communications module operable to communicate with the
communication apparatus using the first component carrier; a communications module operable
to communicate with the communication apparatus using the second co:
measurement module operable to perform measurements on the reference signals of the first type
for the first component carrier, for use in determining a signal strength of the first component
carrier and operable to perform measurements on the reference signals of the second type for the
second component carrier, for use in determining a signal strength of the second component
carrier; a reporting module operable to report, to the communication apparatus, results of the
measurements performed; and a receiver operable to receive, from said communication
apparatus, information for allowing said mobile communication device to communicate using
said second component carrier in said second cell in the event that the results of measurements of
the reference signals of the second type for the second component carrier, indicate that said
mobile communication device is within an area covered by said second cell.
Aspects of the invention extend to computer program products such as computer readable
storage media having instructions stored thereon which are operable to program a programmable
processor to carry out a method as described in the aspects and possibilities set out above or
recited in the claims and/or to program a suitably adapted computer to provide the apparatus
recited in any of the claims.
Each feature disclosed in this specification (which term includes the claims) and/or
shown in the drawings may be incorporated in the invention independently (or in combination
with) any other disclosed and/or illustrated features. In particular but without limitation the
features of any of the claims dependent from a particular independent claim may be introduced
into that independent claim in any combination or individually.
Brief Description of the Drawings
Embodiments of the invention will now be described by way of example only with
reference to the attached figures in which:
Figure 1 schematically illustrates a telecommunication system;
Figure 2 illustrates configuration of component carriers for the telecommunication
system of Figure ;
Figures 3a to 3c show simplified illustrations of resource grids for different reference
signals provided in the telecommunication system of Figure 1;
Figure 4 shows a simplified block diagram of a base station for the telecommunication
system of Figure 1;
Figure 5 shows a simplified block diagram of a mobile communication device for the
telecommunication system of Figure 1; and
Figure 6 shows a simplified flow chart illustrating operation of 1
system of Figure 1.
Best Mode for Embodying the Invention
Overview
Figure 1 schematically illustrates a mobile (cellular) telecommunication system 1 in
which a user of any of a plurality of mobile communication devices 3-1, 3-2, 3-3, 3-4, can
communicate with other users via one or more of a plurality of base stations 5-1, 5-2 and 5-3. In
the system illustrated in Figure 1, each base station 5 shown is an Evolved Universal Terrestrial
Radio Access Network (E-UTRAN) base station capable of operating in a multi-carrier
environment.
In Figure 1, the base station labelled 5-1 comprises a so called 'macro' base station
operating a plurality of relatively geographically large 'macro' cells 7, 8 using respective
component carriers (CCs) C1, C2, of a component carrier set. In this embodiment, the macro
base station 5-1 operates component carrier CI as a primary component carrier on which a
primary cell (PCell) 7 is provided, and component carrier C2 as a secondary component carrier
on which a secondary cell (SCell) 8 is provided. The PCell 7 has a larger geographical coverage
than the SCell 8. The difference in the size of the PCell 7 and SCell 8 may be by design (e.g. as
a result of using a lower transmit power for component carrier C2) or may result from one or
more radio environmental factors affecting the primary carrier CI and secondary carrier C2 to
different extents (e.g. path loss affecting a lower frequency primary carrier C to a lesser extent
than a higher frequency secondary carrier C2).
The other base stations 5-2, 5-3 shown in Figure 1, each comprises a so called 'pico' base
station operating a plurality of 'pico' cells 9-2, 9-3, 10-2, 10-3, using a component carrier set
having component carriers (CCs) CI, C2 corresponding in frequency to those used by the macrobase
station 5-1. Each pico base station 5-2, 5-3 operates a respective pico primary cell (PCell)
9-2, 9-3 on component carrier C2 and a respective pico secondary cell (SCell) 10-2, 10-3 on
component carrier C1. Thus, the pico Pcells 9 share substantially the same frequency band as
the macro Scell 8, and the pico Scells 10 share substantially the same frequency band as the
macro Pcell 7. As seen in Figure 1, the power of the carriers CI, C2 used to provide the pico
cells 9, 10 is set such that the geographical coverage of the pico PCells 9, of this example, are
substantially co-incident with the geographical coverage of the pico SCells 10.
The power used to provide pico cells 9, 10 is low relative to the power used for the macro
cells 7, 8 and the pico cells 9, 10 are therefore small relative to the macro cells 7, 8. As shown in
Figure 1, in this example the geographical coverage of each of the pico
completely within the geographical coverage of the macro PCell 7 and overlaps partially with the
geographical coverage of the macro SCell 7.
Referring to Figure 2, in which the configuration of the component carriers for each of
the cells is illustrated, it will be apparent that there is a potential for relatively high
communication interference between the macro PCell 7 and each of the pico SCells 10. The risk
of interference is high because the macro PCell 7 and pico SCells 10 operate in co-incident
geographical regions and use a common component carrier frequency. Further, the strength of
communication signals from the macro base station 5-1, in the geographical are covered by each
pico Scell 10, may be comparable to communication signals from the respective pico base station
5-2, 5-3 because of the relatively high power used by the macro base station 5-1 compared to
that used by the pico base stations 5-2, 5-3. Whilst there is also the potential for some
interference between the macro SCell 7 and each of the pico PCells 10, any such interference is
likely to be relatively small and restricted to the relatively small geographical region in which the
macro SCell 7 and pico PCells 10 overlap.
To alleviate the issue of interference, the component carrier C2 used for the macro Scell
8 is operated by the macro base station 5-1 as an extension carrier on which the nature of
information that may be transmitted is restricted. Specifically, the component carrier, when
operating as the extension carrier may not be used for transmission of any of the following:
· a Physical Downlink Control Channel (PDCCH);
• a Physical Hybrid ARQ Indicator Channel (PHICH);
• a Physical Control Format Indicator Channel (PCFICH);
• a Physical Broadcast Channel (PBCH);
• a Primary Synchronization Signal (PSS);
· a Secondary Synchronization Signal SSS; or
• a Common Reference Signal / Cell-specific Reference Signal (CRS).
Accordingly, the extension carrier is effectively a 'PDCCH-less' carrier that cannot be
operated as a single (stand-alone) carrier, and must therefore be operated a part of a component
carrier set where at least one of the carriers in the set is a stand-alone-capable carrier. The macro
base station 5-1 operates carrier CI as a stand-alone carrier on which the PDCCH is used to
schedule the resources of component carrier C2 to be used for communication purposes by a
mobile communication device 3 when operating in the macro Scell 8.
The respective component carrier CI used for each of the pico Scells 10 is also each
operated as an extension carrier (as described previously) by the associated pico base station 5-2,
5-3. The respective component carrier C2 used for each of the pico Pet
stand-alone carrier, by the associated pico base station 5-2, 5-3, and is used for cross carrier
scheduling of the resources of component carrier CI to be used for communication purposes by a
mobile communication device 3 when operating in the associated pico Scell 10.
Each base station 5 uses Radio Resource Control (RRC) signalling to configure a
particular mobile communication device 3 for potential operation in the secondary cell 8, 0 that
the base station 5 provides. Once configured in the mobile communication device 3, the SCell 8,
0 is in a deactivated state. In order to activate (and subsequently deactivate) the SCell 8, 10,
therefore, the base station 5 uses Media Access Control (MAC) signalling once the SCell 8, 10
has been configured at the mobile communication device 3.
In scenarios, such as that shown for the macro base station 5-1, in which the component
(extension) carrier C2 used for the SCell 8 covers a significantly smaller geographical area than
the component carrier CI for the PCell 7, a particular mobile communication device 3 may never
enter the geographical area covered by the component (extension) carrier C2 of the SCell 8. In
order to avoid unnecessary configuration and/or activation of the SCell 8, therefore, the mobile
communication device 3 is configured to determine the signal strength of the component
(extension) carrier C2 and to report the results to the macro base station 5-1 so that the macro
base station 5-1 can determine when to configure, and/or add/remove, the component (extension)
carrier C2 as the SCell 8. Specifically, the mobile communication device 3 is configured to
determine and report a measure of the Reference Signal Received Power (RSRP) and the
Reference Signal Received Quality (RSRQ) for the component carrier C2 on which the SCell 8
is operated.
Common reference signals (also known as a cell specific reference signals) are
transmitted in all downlink sub-frames in a cell supporting a physical downlink shared channel
(PDSCH) transmission and operated on a stand-alone carrier. Common reference signals are
transmitted in all downlink sub-frames in a cell-supporting non-MBSFN (Multi-Media Broadcast
over a Single Frequency Network) transmission. In the case of sub-frames used for transmission
with MBSFN, common reference signals are only transmitted in the non-MBSFN region of the
MBSFN sub-frame (e.g. the first two symbols). The common reference signals may be
transmitted on one or several antenna ports (e.g. antenna ports 0 to 3) of the base station (see
3GPP TS 36.21 , vlO.2.0, 6.10.1).
Figure 3a illustrates, generally at 20, a typical resource grid of a sub-frame in which
resources allocated for the purposes of common (Cell-specific) reference signalling. As seen in
Figure 3a, CRSs are communicated in eight resources ('symbols') 12 distributed generally
evenly throughout both slots of the resource grid using four distinct sub
(rows) and two distinct symbol numbers (columns) of each slot. The symbols 11 used for the
CRS include symbols in the control region 1 allocated for the PDCCH and a data region 13.
In the case of the primary cells 7, 9, each mobile communication device 3 is able to
determine a measure of RSRP and/or RSRQ for each component carrier being operated as a
stand-alone carrier using a common reference signal (CRS) that is routinely transmitted on such
carriers (e.g. as defined in the current release 10 version 3GPP TS 36.133 vl0.3.0 sections 9.1.2
and 9.1.5 respectively).
Accordingly, each mobile communication device 3 is able to determine a measure of the
RSRP and/or the RSRQ for component carrier C1 as operated by the macro base station 5- 1, and
for component carrier C2 as operated by the pico base stations 5-2 and 5-3.
However, in the case of the SCells 8, 10, because the component carrier being used is
operated as an extension carrier a CRS is not transmitted and therefore cannot be measured by
the mobile communication device 3. In the communication system of Figure 1, however, each
mobile communication device 3 is advantageously able to determine a value of the RSRP and the
RSRQ, for each extension carrier (component carrier C2 as operated by the macro base station 5-
1, and component carrier CI as operated by each pico base station 5-2, 5-3), based on reference
signals other than the CRS, which reference signals are communicated in resources of the
resource grid that do not include symbols in the control region 11 allocated for the PDCCH.
Specifically, in this embodiment, each mobile communication device 3 is configured to
determine a value of the RSRP and the RSRQ, for a component carrier being operated as an
extension carrier, based on Channel State Information - Reference Signals (CSI-RS). CSI-RS
are generally configured via higher layer signalling for each component carrier including
extension carriers for the purposes of measurements such as rank indicator (RI), precoding
matrix indicator (PMI) and channel quality indicator (CQI). In the case of the macro base station
5-1, in order to configure a mobile communication device 3 for the acquisition and reporting of
such measurements for the component carrier C2 being operated as the extension carrier, the
macro base station 5-1 transmits a measurement configuration message to the mobile
communication device 3 on the stand-alone component carrier CI used for the PCell 7.
In this embodiment, the macro base station 5-1 advantageously makes use of the known
CSI-RS Config information element (which forms part of the known PhysicalConfigDedicated
information element for Pcells and PhysicalConfigDedicatedSCell for Scells) to identify the
CSI-RS configuration to the mobile communication device 3. Macro base station 5-1 also
advantageously makes use of the known "MeasConfig" information element (which is
transmitted in an RRCConnectionReconfiguration message) to identify
performed by the mobile communication device 3, and to identify how the results of the
measurements should be reported to the macro base station 5-1 as RSRP/RSRQ values (for
reference to these messages/information elements, see the current release 10 version 3GPP TS
36.331 (v 10.2.0)).
Figure 3b illustrates, generally at 21, a typical resource grid of a sub-frame in which
resources allocated for the purposes of channel state information (CSI) reference signalling. As
seen in Figure 3a, CSI-RSs are communicated in two adjacent symbols 12 using just a single
sub-carrier frequency and two distinct symbol numbers (for a particular sub-frame - other
frequencies/symbol numbers are used in other sub-frames) of the first slot only. Unlike CRS
signalling, however, the symbols 11 used for the CSI reference signalling include symbols in the
data region 13 but do not include symbols in the control region 1 allocated for the PDCCH.
Whilst, the current technical perception is that measurement of component carrier strength
should use the CRS because of its wider distribution across the resource grid and in the control
channel, it has been found that measurements on CSI-RS can be refined to ensure sufficient
accuracy for the purposes of determining when a mobile communication device enters a region
covered by a secondary cell.
In this embodiment, the mobile communication devices 3 are each configured to use a
Radio Resource Control (RRC) based mechanism in which measurements of the CSI-RS are
performed by the mobile communication device 3, values representing RSRP and RSRQ are
determined from the measurements by the mobile communication device 3, and the results are
then reported to the macro base station 5-1 as an RRC measurement report using RRC signalling
(e.g. using a measResultSCell field in a MeasResults information element of the RRC
MeasurmentReport message referred to in 3GPP TS 36.331 v 10.2.0, section 6.2).
On receipt of the results of the measurement results from the mobile communications
device 3, the macro base station 5-1 analyses the result to determine if the mobile
communication device 3 has entered the coverage area for the extension carrier C2. If the
mobile communication device 3 has entered the coverage area for the extension carrier C2 the
macro base station 5-1 signals, to the mobile communication device 3, configuration information
for the Scell 8 operated on the extension carrier C2 using appropriate RRC signalling (e.g. using
an RRCConnectionReconfiguration message including an sCellToAddModList information
element comprising the appropriate SCell radio resource configuration information as referred to
in 3GPP TS 36.331 v 10.2.0, section 5.3.10.3b). After the mobile communication device 3 has
been configured for operation in the SCell 8, the macro base station 5-1 activates (or
subsequently deactivates) the SCell 8 in the mobile communication dev
using MAC signalling.
If macro base station 5-1 determines that the mobile communication device 3 has left the
coverage area for the extension carrier C2, the macro base station 5-1 signals release of the Scell
8 operated on the extension carrier C2 to the mobile communication device 3, using appropriate
RRC signalling (e.g. using an RRCConnectionReconfiguration message including an
sCellToReleaseList information element comprising information identifying the SCell 8 to be
released as referred to in 3GPP TS 36.331, section 5.3.10.3a).
In this embodiment, the measurement period for the measurement of the CSI-RS
RSRP/RSRQ for the CSI-RS on the extension carrier is advantageously dependent on the timing
parameter scellMeasCycle (for example, five times scellMeasCycle) referred to in 3GPP TS
36.133 v 10.3.0. The mobile communication device 3 continues to perform the RSRP/RSRQ
measurements on the extension carrier in accordance with this cycle both while the SCell 8 is not
configured at the mobile communication device 3 and while the SCell 8 is configured but
deactivated at the mobile communication device 3.
Accordingly, unlike current communication systems, this embodiment advantageously
allows efficient selective configuration (or release) of a secondary cell operated on an extension
carrier, at a mobile communication device, in dependence on whether or not the mobile
communication device has entered the coverage of the extension carrier. Thus, even if the
mobile communication device enters a primary cell operated on a first carrier by a base station it
will not be configured for communication in a secondary cell on a second - extension - carrier
operated by that base station, until the mobile communication device enters the coverage area of
that extension carrier.
It will be appreciated that embodiments of the present invention are also particularly
advantageous in many other scenarios in which a base station operates different cells which are
not geographically co-incident. For example, if a base station operates a first cell on an
extension carrier using a first antenna that is directed (sectorised) such that it partially overlaps
part (e.g. half the area) covered by a second cell on a second component carrier (and possibly
part of the area covered by a third cell operated on a third component carrier).
Base Station
Figure 4 is a block diagram illustrating the main components of the base stations 5 shown
in Figure 1. For clarity, the base stations will be described with reference to the macro base
station 5-1, but it will be appreciated that each of the pico base stations 5-2, 5-3 may be
configured similarly. The macro base station 5-1 comprises an E-UTRAN multi-carrier capable
base station comprising a transceiver circuit 31 which is operable to trai
receive signals from, the mobile communication devices 3 via at least one antenna 33. The base
station 5-1 is also operable to transmit signals to and to receive signals from a core network via a
network interface 35. The operation of the transceiver circuit 3 1 is controlled by a controller 37
in accordance with software stored in memory 39.
The software includes, among other things, an operating system 41, a communication
control module 42, a component carrier management module 43, measurement module 45 and an
SCell management module 47.
The communication control module 42 is operable to control communication with the
mobile communication devices 3 on the component carriers (CCs) CI, C2, of its component
carrier set. The component carrier management module 43 is operable to manage the use of the
component carriers CI, C2 and in particular the configuration and operation of the PCell 7 and
SCell 8 and the operation of the component carrier for the SCell 8 as an extension carrier. The
measurement module 45 communicates with the mobile communication device 3 to configure
the mobile communication device 3 to initiate measurement of the CSI-RS on the extension
carrier for the purposes of determining the RSRP and RSRQ of the extension carrier. The
measurement module 45 also analyses measurement reports received from the mobile
communication device 3, to extract the RSRP and RSRQ measurement results, in order to
determine whether or not the mobile communication device 3 is within sufficient range of the
extension carrier for SCell configuration. The SCell management module 47 manages
communication with the mobile communication device 3 for the configuration of the SCell 8 and
its activation/deactivation, at the mobile communication device 3, when the mobile
communication device 3 is within sufficient range of the extension carrier as indicated by the
RSRP and RSRQ measurements. The SCell management module 47 also manages
communication with the mobile communication device 3 for the release of the SCell 8 at the
mobile communication device 3, when the mobile communication device 3 is no longer within
sufficient range of the extension carrier as indicated by the RSRP and RSRQ measurements.
In the above description, the base station 5-1 is described for ease of understanding as
having a number of discrete modules. Whilst these modules may be provided in this way for
certain applications, for example where an existing system has been modified to implement the
invention, in other applications, for example in systems designed with the inventive features in
mind from the outset, these modules may be built into the overall operating system or code and
so these modules may not be discernible as discrete entities.
Mobile Communication Device
Figure 5 is a block diagram illustrating the main components of
communication devices 3 shown in Figure 1. Each mobile communication device 3 comprises a
mobile (or 'cell' telephone) capable of operating in a multi-carrier environment. The mobile
communication device 3 comprises a transceiver circuit 51 which is operable to transmit signals
to, and to receive signals from, the base stations 5 via at least one antenna 53. The operation of
the transceiver circuit 5 is controlled by a controller 57 in accordance with software stored in
memory 59.
The software includes, among other things, an operating system 51, a communication
control module 62, a measurement module 65, and an SCell configuration module 67.
The communication control module 62 is operable for managing communication with the
base stations 5 on the associated component carriers (CCs) CI, C2. The measurement module 65
receives measurement configuration information from the base station 5 for the purposes of
configuring the mobile communication device 3 to take measurements of the CSI-RS on the
extension carrier for the purposes of determining the RSRP and RSRQ of the extension carrier.
The measurement module 65 manages performance of the measurements, determines the RSRP
and RSRQ, generates associated measurement reports and transmits the generated reports to the
base station 5. The measurement module 65 also manages the performance of other
measurements such as, for example, measurements of the CRS communicated on a component
carrier used for operating a PCell.
The SCell management module 67 manages communication with the base station 5 for
the purposes of configuring the SCell 8, and activating/deactivating it, at the mobile
communication device 3, when the mobile communication device 3 is within sufficient range of
the extension carrier. The SCell management module 67 also manages communication with the
base station 5 for the purposes of releasing the SCell 8 at the mobile communication device 3,
when the mobile communication device 3 is no longer within sufficient range of the extension
carrier. On receipt of an SCell configuration message from the base station 5, the SCell
management module 67 stores associated SCell configuration information 69 in memory.
In the above description, the mobile communication device 3 is described for ease of
understanding as having a number of discrete modules. Whilst these modules may be provided
in this way for certain applications, for example where an existing system has been modified to
implement the invention, in other applications, for example in systems designed with the
inventive features in mind from the outset, these modules may be built into the overall operating
system or code and so these modules may not be discernible as discrete entities.
Operation
Figure 6 is a flow chart illustrating operation of the communicat
a mobile communication device (MCD) 3 for operation in a secondary cell of the macro base
station (BS) 5-1 in accordance with the current embodiment.
As seen in Figure 6, when the mobile communication device 3 enters the primary cell 7
of the base station 5-1 at SI, the base station 5-1 signals appropriate measurement configuration
information to the mobile communication device 3 at S2. In this embodiment the measurement
configuration information comprises information for the CSI-RS on the extension carrier which
the base station 5-1 uses to operate its secondary cell 8. Thus, the mobile communication device
3 not only measures the CRS of the component carrier used for the primary cell 7 but also
measures a different type of reference signal - the CSI-RS in this embodiment - for the
extension carrier as S3. The mobile communication device 3 generates an associated
measurement report comprising the results of the measurements (in this embodiment values of
RSRP and RSRQ) and sends it to the base station 5-1 at S4. The base station 3 then determines,
from the measurement results, whether or not the mobile communication device 3 is within the
coverage area of the secondary cell 8 at S5. If the mobile communication device 3 is within the
coverage area of the secondary cell 8, then the base station 5-1 signals the configuration
information for the secondary cell 8 to the mobile communication device 3 at S6. On receipt of
this information, the mobile communication device 3 stores the secondary cell configuration
information for use when the secondary cell 8 is activated on that mobile communication device
3 at S7. The base station 5-1 is then able to signal the mobile communication device 3 to
activate (and subsequently deactivate) the secondary cell configuration information, if required,
at S8. The mobile communication device continues to periodically measure the CSI-RS (e.g. as
shown at S9) and report the results. If the mobile communication device 3 is within the coverage
area of the secondary cell 8, then the base station 3 continues to monitor the periodic
measurement reports sent from the mobile communication device 3 to determine when the
mobile communication device 3 does enter the coverage area of the secondary cell's extension
carrier.
Modifications and alternatives
A detailed embodiment and has been described above. As those skilled in the art will
appreciate, a number of modifications and alternatives can be made to the above embodiment
and variations whilst still benefiting from the inventions embodied therein.
In the above embodiment or another embodiment, for example, the base stations 5 and
mobile communication devices 3, may be configured to use measurements of a different signal,
in addition or as an alternative to measurements based on the CSI-RS, base upon which the base
station 5 can determine whether or not the mobile communication devic
extension carrier it operates. For example, the base stations 5 and mobile communication
devices 3 may be configured to use measurements of Positioning Reference Signals (PRSs) (e.g.
as defined in 3GPP TS 36.21 1, v 10.2.0, section 6.10.4).
Positioning reference signals are only transmitted in resource blocks in downlink subframes
configured for positioning reference signal transmission. If both normal and MBSFN
sub-frames are configured as positioning sub-frames within a cell, the OFDM symbols in a
MBSFN sub-frame configured for positioning reference signal transmission use the same cyclic
prefix as used for sub-frame number zero. If only MBSFN sub-frames are configured as
positioning sub-frames within a cell, the OFDM symbols configured for positioning reference
signals in these sub-frames use an extended cyclic prefix length. In a sub-frame configured for
positioning reference signal transmission, the starting positions of the OFDM symbols
configured for positioning reference signal transmission are substantially identical to those in a
sub-frame in which all OFDM symbols have the same cyclic prefix length as the OFDM symbols
configured for positioning reference signal transmission. Positioning reference signals are
transmitted on a dedicated antenna port (typically antenna port 6).
Figure 3c illustrates, generally at 23, a typical resource grid of a sub-frame in which
resources allocated for the purposes of positioning reference signalling. As seen in Figure 3a,
PRSs are typically communicated in symbols 12 distributed throughout the region of the subframe
that has not been allocated for the PDCCH, using most of the sub-carrier frequencies and
most symbol numbers somewhere in the two slots (for a particular sub-frame - other
frequencies/symbol numbers are used in other sub-frames). Unlike CRS signalling, therefore,
the symbols 11 used for the positioning reference signalling include symbols in the data region
13 but do not include symbols in the control region 11 allocated for the PDCCH. As mentioned
above, the current technical perception is that measurement of component carrier strength should
use the CRS because of its wider distribution across the resource grid including the control
channel. It has been found, however, that measurements on PRS can be refined to ensure
sufficient accuracy for the purposes of determining when a mobile communication device enters
a region covered by a secondary cell. Using the PRS has a wider resource distribution the CSIRS
but using PRS is more involved and is likely to require more significant changes to current
practice to implement its use.
In the case of PRSs, for example, the communication system 1may comprise a so called
'Serving Mobile Location Center' (SMLC), which is a network element that calculates networkbased
location of a mobile communications device. In such an embodiment, the SMLC provides
a list of cells to be included in Reference Signal Time Difference (RST
Observed Time Difference Of Arrival (OTDOA) measurements. The SMLC determines that the
extension carrier should be included in the extension carriers for the OTDOA measurements and
identifies the configuration of PRSs broadcast on the extension carrier(s) to the mobile
communication device 3.
In this embodiment, when a mobile communications device 3 enters the primary cell 7 of
the macro base station 5-1, the macro base station 5-3 informs the mobile communication device
3 of the existence of the extension carrier C2 on which the secondary cell operates using RRC
signalling (for example using an RRC MeasConfig message). The mobile communication device
3 performs measurements of the PRS broadcast on the extension carrier, determines
RSRP/RSRQ values for the extension carrier from these measurements, and reports the
RSRP/RSRQ values to the base station 5-1 in a measurement report as described previously.
Because it is the SMLC and not the base station 5-1 that initiates the measurements, the base
station 5-1 does not know that the measurements are being carried out. Accordingly, in this
embodiment, the mobile communication device 3 informs the base station 5-1 that it is
performing the OTDOA measurements using appropriate RRC signalling (for example using the
InterFreqRSTDMeasurementlndication message defined in 3GPP TS 36.331, v 10.2.0, section
6.2.1) to indicate that the mobile communication is going to start (or subsequently stop OTDOA
inter-frequency RSTD measurement, which requires measurement gaps (e.g. as specified in
3GPP TS 36. 133). The RRC signalling also indicates the smallest offset of the PRS positioning
occasions in the carrier frequency {carrierFreq IE in the InterFreqRSTDMeasurementlndication
message) for which the mobile communication device 3 needs to perform the inter-frequency
RSTD measurements.
The SMLC may either be a separate network element or may be integrated into the
functionality of a base station or other communication node.
It will also be appreciated, that the base stations 5 and mobile communication devices 3
may be configured to use a dedicated reference signal provided on the extension carrier for the
purposes of providing RSRP and RSRQ measurements to the base station 5 as an alternative to
or in addition to the PRS and/or CSI-RS.
Further, although RRC based measurement and reporting of the RSRP and RSRQ is
particularly advantageous, it will be appreciated that measurement may be based in other layers,
for example, the physical and/or MAC layers. Specifically, the mobile communication device 3
may perform CQI measurements and report the results to the base station 5 on the component
carrier of the primary cell. The base station may then translate the CQI report into an RRC
measurement report (including RSRP/RSRQ values) through inter-layei
base station 5. The base station 5 can then use the information in the RRC measurement report
to determine when to configure the secondary cell and when to release the secondary cell
configuration at the mobile communication device 3.
Whilst, in current communication systems, CQI reports include measurements when a
component carrier frequency has been activated, in the current embodiment, CQI measurements
will also be carried out when the secondary cell is not configured and/or has not been activated.
It will be appreciated that although the communication system 1 is described in terms of
base stations 5 operating as macro or pico base stations, the same principles may be applied to
base stations operating as femto base stations, relay nodes providing elements of base station
functionality, or other such communication nodes.
It will further be appreciated that although the embodiments described above
advantageously reuse known parameters defined in the relevant standards (e.g. the measurement
cycle being based on the parameter scellMeasCycle) a dedicated parameter may be defined.
Moreover, the measurement cycle is based on scellMeasCycle it may be any suitable multiple of
scellMeasCycle for example any appropriate integer or fraction multiple (e.g. ¼, ½ , 1, 2 , 3, 5,
10, 15, 20 anywhere therebetween).
In the above embodiments, a mobile telephone based telecommunications system was
described. As those skilled in the art will appreciate, the signalling techniques described in the
present application can be employed in other communications system. Other communications
nodes or devices may include user devices such as, for example, personal digital assistants,
laptop computers, web browsers, etc. As those skilled in the art will appreciate, it is not essential
that the above described relay system be used for mobile communications devices. The system
can be used to extend the coverage of base stations in a network having one or more fixed
computing devices as well as or instead of the mobile communicating devices.
In the embodiments described above, the base stations 5 and mobile communication
devices 3 each include transceiver circuitry. Typically, this circuitry will be formed by dedicated
hardware circuits. However, in some embodiments, part of the transceiver circuitry may be
implemented as software run by the corresponding controller.
In the above embodiments, a number of software modules were described. As those
skilled in the art will appreciate, the software modules may be provided in compiled or uncompiled
form and may be supplied to the base station or the relay station as a signal over a
computer network, or on a recording medium. Further, the functionality performed by part or all
of this software may be performed using one or more dedicated hardware circuits.
Various other modifications will be apparent to those skilled in
described in further detail here.
This application is based upon and claims the benefit of priority from United Kingdom
patent application No. 11 1374.3, filed on July 4, 201 1, the disclosure of which is incorporated
herein in its entirety by reference.

CLAIMS
Communication apparatus for a cellular communication system, the communication
apparatus comprising:
means for operating a first cell using a first component carrier and a second cell using a
second component carrier, wherein:
reference signals of a first type are provided in a control region and in a data
region of sub-frames communicated using the first component carrier;
the reference signals of the first type are not provided in sub-frames
communicated using the second component carrier; and
reference signals of a second type are provided in a data region but are not
provided in a control region of sub-frames communicated using the second
component carrier;
means for communicating with a mobile communication device using the first
component carrier;
means for communicating with the mobile communication device using the second
component carrier;
means for receiving, from the mobile communication device, results of measurements
performed on the reference signals of the first type for the first component carrier and
results of measurements performed on the reference signals of the second type for the
second component carrier;
means for determining, from the results of the measurements performed on the reference
signals of the second type, whether or not said mobile communication device is within an
area covered by said second cell; and
means for transmitting to the mobile communication device, in dependence on whether
or not said mobile communication device is within an area covered by said second cell,
information for allowing said mobile communication device to communicate using said
second component carrier in said second cell.
A mobile communication device for communicating with communication apparatus of a
cellular communication system, which communication apparatus is configured to operate
a first cell using a first component carrier and a second cell using a second component
carrier, wherein:
reference signals of a first type are provided in a control region and in a data
region of sub-frames communicated using the first component carrier;
the reference signals of the first type are not provided in sub-frames
communicated using the second component carrier; and
reference signals of a second type are provided in a data region but are not
provided in a control region of sub-frames communicated using the second
component carrier; and
wherein the mobile communication device comprises:
means for communicating with the communication apparatus using the first
component carrier;
means for communicating with the communication apparatus using the second
component carrier;
means for performing measurements on the reference signals of the first type for
the first component carrier for use in determining a signal strength of the first
component carrier, and for performing measurements on the reference signals of
the second type for the second component carrier for use in determining a signal
strength of the second component carrier;
means for reporting, to the communication apparatus, results of the measurements
performed; and
means for receiving, from said communication apparatus, information for
allowing said mobile communication device to communicate using said second
component carrier in said second cell in the event that the results of measurements
of the reference signals of the second type for the second component carrier
indicate that said mobile communication device is within an area covered by said
second cell.
Communication apparatus for a cellular communication system, the communication
apparatus comprising:
means for operating a first cell using a first component carrier and a second cell using a
second component carrier, wherein a control channel and reference signals of a first type
are provided using the first component carrier, and wherein the control channel and the
reference signals of the first type are not provided, and reference signals of a second type
are provided, using the second component carrier;
means for communicating with a mobile communication device using the first
component carrier;
means for communicating with the mobile communication device using the second
component carrier;
means for receiving, from the mobile communication device, results of measurements
performed on the reference signals of the first type for the first
results of measurements performed on the reference signals of the second type for the
second component carrier;
means for determining, from the results of the measurements performed on the reference
signals of the second type, whether or not said mobile communication device is within an
area covered by said second cell; and
means for transmitting to the mobile communication device, in dependence on whether
or not said mobile communication device is within an area covered by said second cell,
information for allowing said mobile communication device to communicate using said
second component carrier in said second cell.
Communication apparatus according to claim 3, wherein: the reference signals of the first
type are provided in a control region and in a data region of sub-frames communicated
using the first component carrier; and the reference signals of the second type are
provided in a data region but are not provided in a control region, of sub-frames
communicated using the second component carrier.
Communication apparatus according to any of claims 1 or 3 to 4 further comprising
means for providing measurement configuration information to the mobile
communication device for configuring said mobile communication device to perform
said measurements on the reference signals of the second type.
Communication apparatus according to any of claims 1 or 3 to 5 wherein said
determining means is operable to determine a reference signal received power 'RSRP'
for the second component carrier from said received results of measurements performed
on the reference signals of the second type.
Communication apparatus according to any of claims 1 or 3 to 6 wherein said
determining means is operable to determine a reference signal received quality 'RSRQ'
for the second component carrier from said received results of measurements performed
on the reference signals of the second type.
Communication apparatus according to any of claims 1 or 3 to 7 wherein the
communication apparatus comprises at least one of a serving mobile location center
' SML and a base station.
A mobile communication device for communicating with communication apparatus of a
cellular communication system, which communication apparatus is configured to operate
a first cell using a first component carrier and a second cell using a second component
carrier, wherein a control channel and reference signals of a first type are provided using
the first component carrier, wherein the control channel and the
first type are not provided, and reference signals of a second type are provided using the
second component carrier, and wherein:
the mobile communication device comprises:
means for communicating with the communication apparatus using the first
component carrier;
means for communicating with the communication apparatus using the second
component carrier;
means for performing measurements on the reference signals of the first type for
the first component carrier, for use in determining a signal strength of the first
component carrier and for performing measurements on the reference signals of
the second type for the second component carrier, for use in determining a signal
strength of the second component carrier;
means for reporting, to the communication apparatus, results of the measurements
performed; and
means for receiving, from said communication apparatus, information for
allowing said mobile communication device to communicate using said second
component carrier in said second cell in the event that the results of measurements
of the reference signals of the second type for the second component carrier,
indicate that said mobile communication device is within an area covered by said
second cell.
A mobile communication device according to claim 9 wherein: the reference signals of
the first type are provided in a control region and in a data region of sub-frames
communicated using the first component carrier; and the reference signals of the second
type are provided in a data region but are not provided in a control region of sub-frames
communicated using the second component carrier.
A mobile communication device according to any of claims 2 or 9 to 10 wherein said
measurement means is operable to determine a reference signal received power 'RSRP'
for the second component carrier from said reference signal of the second type.
A mobile communication device according to any of claims 2 or 9 to 1 wherein said
measurement means is operable to determine a reference signal received quality 'RSRQ'
for the second component carrier from said reference signal of the second type.
A mobile communication device according to any of claims 2 or 9 to 1 wherein said
measurement means is operable to determine at least one of a rank indicator (RI),
WO 2013/005855 PCT/JP2012/067412
precoding matrix indicator (PMI) and a channel quality indicato
reference signal of the second type.
14. A mobile communication device according to any of claims 2 or 9 to 3 further
comprising means for receiving measurement configuration information from the
communication apparatus, and means for configuring said mobile communication device
to perform said measurements on the reference signals of the second type.
15. Communication apparatus according to any of claims 1, or 3 to 8 or a mobile
communication device according to any of claims 2 or 9 to 14 wherein said reference
signals of the second type comprise channel state information reference signals 'CSI-RS'.
16. Communication apparatus according to any of claims 1, 3 to 8 or 15 or a mobile
communication device according to any of claims 2 or 9 to 15 wherein said reference
signals of the second type comprise positioning reference signals 'PRS'.
17. Communication apparatus according to any of claims 1, 3 to 8 or 15 to 16 or a mobile
communication device according to any of claims 2 or 9 to 16 wherein said reference
signals of the second type comprise common reference signals 'CRS' or Cell-specific
reference signals 'CRS'.
18. Communication apparatus according to any of claims 1, 3 to 8 or 15 to 17 or a mobile
communication device according to any of claims 2 or 9 to 17 wherein said second
component carrier comprises an extension carrier.
19. Communication apparatus according to any of claims 1, 3 to 8 or 15 to 18 or a mobile
communication device according to any of claims 2 or 9 to 18 wherein said first carrier
comprises a stand alone carrier.
20. Communication apparatus according to any of claims 1, 3 to 8 or 15 to 19 or a mobile
communication device according to any of claims 2 or 9 to 19 wherein said control
region of said sub-frames comprises a region normally reserved for a physical downlink
control channel.
21. A communication system comprising at least one communication apparatus according to
any of claims 1, 3 to 8 or 15 to 20 and at least one mobile communication device
according to any of claims 2 or 9 to 20.
22. A computer program product comprising instructions operable to program a
programmable processor to implement communication apparatus according to any of
claims 1, 3 to 8 or 15 to 20 or a mobile communication device according to any of claims
2 or 9 to 20.
23. A method preformed by communication apparatus for a cellular communication system,
the method comprising:
operating a first cell using a first component carrier and a second cell using a second
component carrier, wherein a control channel and reference signals of a first type are
provided using the first component carrier, and wherein the control channel and the
reference signals of the first type are not provided, and reference signals of a second type
are provided, using the second component carrier;
communicating with a mobile communication device using the first component carrier;
receiving, from the mobile communication device, results of measurements performed on
the reference signals of the first type for the first component carrier and results of
measurements performed on the reference signals of the second type for the second
component carrier;
determining, from the results of the measurements performed on the reference signals of
the second type, whether or not said mobile communication device is within an area
covered by said second cell; and
transmitting to the mobile communication device, in dependence on whether or not said
mobile communication device is within an area covered by said second cell, information
for allowing said mobile communication device to communicate using said second
component carrier in said second cell.
A method preformed by a mobile communication device for communicating with
communication apparatus of a cellular communication system, which communication
apparatus is configured to operate a first cell using a first component carrier and a second
cell using a second component carrier, wherein a control channel and reference signals of
a first type are provided using the first component carrier, wherein the control channel
and the reference signals of the first type are not provided, and reference signals of a
second type are provided using the second component carrier, and wherein:
the method comprises:
communicating with the communication apparatus using the first component
carrier;
performing measurements on the reference signals of the first type for the first
component carrier, for use in determining a signal strength of the first component
carrier;
performing measurements on the reference signals of the second type for the
second component carrier, for use in determining a signal strength of the second
component carrier;
reporting, to the communication apparatus, results of the
performed; and
receiving, from said communication apparatus, information for allowing said
mobile communication device to communicate using said second component
carrier in said second cell in the event that the results of measurements of the
reference signals of the second type for the second component carrier, indicate
that said mobile communication device is within an area covered by said second
cell.
A method according to any of claims 23 to 24 wherein: the reference signals of the first
type are provided in a control region and in a data region of sub-frames communicated
using the first component carrier; and the reference signals of the second type are
provided in a data region but are not provided in a control region of sub-frames
communicated using the second component carrier.
A computer program product comprising instructions to perform a method according to
any of claims 23 to 25.
Communication apparatus for a cellular communication system, the communication
apparatus comprising:
a controller operable to operate a first cell using a first component carrier and a second
cell using a second component carrier, wherein a control channel and reference signals of
a first type are provided using the first component carrier, and wherein the control
channel and the reference signals of the first type are not provided, and reference signals
of a second type are provided, using the second component carrier;
a communications module operable to communicate with a mobile communication
device using the first component carrier;
a communications module operable to communicate with the mobile communication
device using the second component carrier;
a receiver module operable to receive, from the mobile communication device, results of
measurements performed on the reference signals of the first type for the first component
carrier and results of measurements performed on the reference signals of the second type
for the second component carrier;
a determiner operable to determine, from the results of the measurements performed on
the reference signals of the second type, whether or not said mobile communication
device is within an area covered by said second cell; and
means for transmitting to the mobile communication device, in dependence on whether
or not said mobile communication device is within an area cove
information for allowing said mobile communication device to communicate using said
second component carrier in said second cell.
A mobile communication device for communicating with communication apparatus of a
cellular communication system, which communication apparatus is configured to operate
a first cell using a first component carrier and a second cell using a second component
carrier, wherein a control channel and reference signals of a first type are provided using
the first component carrier, wherein the control channel and the reference signals of the
first type are not provided, and reference signals of a second type are provided using the
second component carrier, and wherein:
the mobile communication device comprises:
a communications module operable to communicate with the communication
apparatus using the first component carrier;
a communications module operable to communicate with the communication
apparatus using the second component carrier;
a measurement module operable to perform measurements on the reference
signals of the first type for the first component carrier, for use in determining a
signal strength of the first component carrier and operable to perform
measurements on the reference signals of the second type for the second
component carrier, for use in determining a signal strength of the second
component carrier;
a reporting module operable to report, to the communication apparatus, results of
the measurements performed; and
a receiver operable to receive, from said communication apparatus, information
for allowing said mobile communication device to communicate using said
second component carrier in said second cell in the event that the results of
measurements of the reference signals of the second type for the second
component carrier, indicate that said mobile communication device is within an
area covered by said second cell.