U.S. patent application number 14/611984 was filed with the patent office on 2015-06-04 for apparatus and method for scheduling in carrier aggregated communication systems based on a transmit-receive-frequency gap band.
The applicant listed for this patent is Cellular Communications Equipment LLC. Invention is credited to Frank Frederiksen, Wigard Jeroen, Klaus Ingemann Pedersen, Sabine Roessel.
Application Number | 20150156778 14/611984 |
Document ID | / |
Family ID | 43821930 |
Filed Date | 2015-06-04 |
United States Patent
Application |
20150156778 |
Kind Code |
A1 |
Roessel; Sabine ; et
al. |
June 4, 2015 |
APPARATUS AND METHOD FOR SCHEDULING IN CARRIER AGGREGATED
COMMUNICATION SYSTEMS BASED ON A TRANSMIT-RECEIVE-FREQUENCY GAP
BAND
Abstract
An apparatus, method, system and computer program product is
configured for avoiding base station self-interference due to
transmit intermodulation in carrier aggregated communication
systems. Physical downlink communication channels are allocated to
respective component carriers per time interval according to a
communication service in which communication is performed on an
aggregation of component carriers of one or more frequency band
such that component carriers to be used for transmission are
separated from component carriers to be used for receiving by a
transmit-receive-frequency gap band. However, not all available
component carriers to be used for transmission are allocated in the
same time interval. Rather, in each time interval, the physical
downlink communication channels to be allocated for transmission
are allocated to the available component carriers to be used for
transmission such that, in each frequency band, the overall
emission spectrum does not reach beyond the
transmit-receive-frequency gap band.
Inventors: |
Roessel; Sabine; (Munich,
DE) ; Frederiksen; Frank; (Klarup, DK) ;
Pedersen; Klaus Ingemann; (Aalborg, DK) ; Jeroen;
Wigard; (Klarup, DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cellular Communications Equipment LLC |
Plano |
TX |
US |
|
|
Family ID: |
43821930 |
Appl. No.: |
14/611984 |
Filed: |
February 2, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13521601 |
Oct 2, 2012 |
8948110 |
|
|
PCT/EP2010/050269 |
Jan 12, 2010 |
|
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14611984 |
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Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04L 5/0053 20130101;
H04L 5/0066 20130101; H04L 5/0062 20130101; H04L 5/001 20130101;
H04L 5/0032 20130101; H04L 5/0073 20130101; H04W 72/0453 20130101;
H04W 72/042 20130101; H04L 5/0091 20130101; H04L 5/0035 20130101;
H04L 5/0007 20130101 |
International
Class: |
H04W 72/04 20060101
H04W072/04 |
Claims
1. An apparatus, comprising: scheduling means configured to
schedule allocation of physical downlink communication channels to
respective component carriers per time interval according to a
communication service in which communication is performed on an
aggregation of component carriers of one or more frequency band
such that component carriers to be used for transmission are
separated from component carriers to be used for receiving by a
transmit-receive-frequency gap band, wherein the scheduling means
is further configured so that not all available component carriers
to be used for transmission are allocated in the same time
interval, and wherein the scheduling means is further configured so
that, in each time interval, the physical downlink communication
channels to be allocated for transmission are allocated to the
available component carriers to be used for transmission such that,
in each frequency band, the overall emission spectrum does not
reach beyond the transmit-receive-frequency gap band.
2. The apparatus according to claim 1, wherein the physical
downlink communication channels comprise a physical channel for
broadcast communication and a primary and a secondary
synchronization channel.
3. The apparatus according to claim 1, wherein the physical
downlink communication channels comprise a physical channel
configured for downlink control, and wherein the apparatus further
comprises: radio resource control means configured to exclude
certain component carriers to be used for transmission from having
allocated the physical channel configured for downlink control; and
allocation communicating means configured to communicate, on a
component carrier which is not excluded by the radio resource
control means, information that the excluded component carriers are
not to be monitored, allocation of a physical channel configured
for shared uplink use to a component carrier to be used for
receiving and allocation of a physical channel configured for
shared downlink use to a component carrier to be used for
transmission, and wherein the scheduling means is further
configured to allocate, for consecutive time intervals, the
physical channel configured for downlink control to not excluded
component carriers to be used for transmission.
4. The apparatus according to claim 3, wherein the physical
downlink communication channels comprise a physical channel
configured for hybrid automatic repeat request indication, and the
scheduling means is further configured to exclude those component
carriers to be used for transmission from having allocated the
physical channel configured for hybrid automatic repeat request
indication which are excluded by the radio resource control means
from having allocated the physical channel configured for downlink
control.
5. The apparatus according to claim 3, wherein the physical
downlink communication channels comprise a physical control channel
configured for format indication, and the scheduling means is
further configured to exclude those component carriers to be used
for transmission from having allocated the physical control channel
configured for format indication which are excluded by the radio
resource control means from having allocated the physical channel
configured for downlink control.
6. The apparatus according to claim 1, wherein the physical
downlink communication channels comprise a physical channel
configured for shared downlink use.
7. The apparatus according to claim 6, wherein the scheduling means
is further configured to apply dynamic downlink inter-cell
interference coordination.
8. A method, comprising: allocating physical downlink communication
channels to respective component carriers per time interval
according to a communication service in which communication is
performed on an aggregation of component carriers of one or more
frequency band such that component carriers to be used for
transmission are separated from component carriers to be used for
receiving by a transmit-receive-frequency gap band, wherein not all
available component carriers to be used for transmission are
allocated in the same time interval, and wherein, in each time
interval, the physical downlink communication channels to be
allocated for transmission are allocated to the available component
carriers to be used for transmission such that, in each frequency
band, the overall emission spectrum does not reach beyond the
transmit-receive-frequency gap band.
9. The method according to claim 8, wherein the physical downlink
communication channels comprise a physical channel for broadcast
communication and a primary and a secondary synchronization
channel.
10. The method according to claim 8, wherein the physical downlink
communication channels comprise a physical channel configured for
downlink control, the method further comprising: excluding certain
component carriers to be used for transmission from having
allocated the physical channel con-figured for downlink control;
communicating, on a component carrier which is not excluded by the
radio resource control means, information that the excluded
component carriers are not to be monitored, allocation of a
physical channel configured for shared uplink use to a component
carrier to be used for receiving and allocation of a physical
channel configured for shared downlink use to a component carrier
to be used for transmission; and allocating, for consecutive time
intervals, the physical channel configured for downlink control to
not excluded component carriers to be used for transmission.
11. The method according to claim 10, wherein the physical downlink
communication channels comprise a physical channel configured for
hybrid automatic repeat request indication, the method further
comprising: excluding those component carriers to be used for
transmission from having allocated the physical channel configured
for hybrid automatic repeat request indication which are excluded
from having allocated the physical channel configured for downlink
control.
12. The method according to claim 10, wherein the physical downlink
communication channels comprise a physical control channel
configured for format indication, and the method further
comprising: excluding those component carriers to be used for
transmission from having allocated the physical control channel
configured for format indication which are excluded from having
allocated the physical channel configured for downlink control.
13. The method according to claim 8, wherein the physical downlink
communication channels comprise a physical channel configured for
shared downlink use.
14. The method according to claim 13, further comprising: applying
dynamic downlink inter-cell interference coordination.
15. A computer program product comprising computer-executable
components which perform, when the program is run on a computer:
allocating physical downlink communication channels to respective
component carriers per time interval according to a communication
service in which communication is performed on an aggregation of
component carriers of one or more frequency band such that
component carriers to be used for transmission are separated from
component carriers to be used for receiving by a
transmit-receive-frequency gap band, wherein not all available
component carriers to be used for transmission are allocated in the
same time interval, and wherein, in each time interval, the
physical downlink communication channels to be allocated for
transmission are allocated to the available component carriers to
be used for transmission such that, in each frequency band, the
overall emission spectrum does not reach beyond the
transmit-receive-frequency gap band.
16. The computer program product according to claim 15, embodied as
a computer-readable storage medium.
Description
[0001] The present application is a continuation of U.S.
application Ser. No. 13/521,601, filed Jul. 11, 2012 with an
assigned .sctn.371(c) acceptance date of Oct. 2, 2012 (Publication
No. 2013/0021990); which is a National Stage Entry under 35 U.S.C.
.sctn.371 of PCT/EP2010/050269, filed Jan. 12, 2010.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an apparatus, method,
system and computer program product for avoiding base station
self-interference due to transmit intermodulation in carrier
aggregated communication systems.
[0004] 2. Related Background Art
[0005] Prior art which is related to this technical field can e.g.
be found by the technical specifications TS 36.211 current version:
9.0.0), TS 36.212 (current version 9.0.0), and TS 36.213 (current
version: 9.0.1) of the 3GPP, and by the contributions according to
document R4-093091, document R4-093220 and document R4-093439 of
the working group 4 of the 3GPP related to radio access
networks.
[0006] The following meanings for the abbreviations used in this
specification apply: [0007] 3GPP: 3.sup.rd Generation Partnership
Project [0008] CC: Component Carrier [0009] DL: Downlink [0010]
eNB: evolved Node B (eNode B) [0011] GSM: Global System for Mobile
Communication [0012] HARQ: Hybrid Automatic Repeat Request [0013]
ICIC: Inter-Cell Interference Coordination [0014] LTE: Long Term
Evolution [0015] OFDMA: Orthogonal Frequency Division Multiple
Access [0016] PBCH: Physical Broadcast Channel [0017] PCFICH:
Physical Control Format Indicator Channel [0018] PDCCH: Physical
Downlink Control Channel [0019] PDSCH: Physical Downlink Shared
Channel [0020] PHICH: Physical HARQ Indicator Channel [0021] PS:
Public Safety [0022] PSS: Primary Synchronization Channel [0023]
PUSCH: Physical Uplink Shared Channel [0024] RRC: Radio Resource
Control [0025] SC-FDMA: Single Carrier Frequency Division Multiple
Access [0026] SFN: Sub-Frame Numbering [0027] SSS: Secondary
Synchronization Channel [0028] TTI: Transmission Time Interval
[0029] UE: User Equipment [0030] UL: Uplink
[0031] In recent years, 3GPP's LTE as the upcoming standard is
under particular research. The base station of LTE is called
eNodeB. LTE is expected to be based on OFDMA in downlink and
SC-FDMA in uplink. Both schemes allow the division of the uplink
and downlink radio resources in frequency and time, i.e. specific
frequency resources will be allocated for certain time duration to
the different UE. The access to the uplink and downlink radio
resources is controlled by the eNode B that controls the allocation
of the frequency resources for certain time slots.
[0032] As a further development of LTE, an extension of
transmission bandwidth is considered. This evolution of LTE,
referred to as LTE-advanced, aims at exploiting spectrum
allocations up to 100 MHz. Though, this bandwidth extension is made
while preserving spectrum compatibility, which is achieved with
so-called carrier aggregation, where multiple component carriers
are aggregated to provide the necessary bandwidth.
[0033] However, by e.g. referring to the example of lower and upper
700 MHz frequency band as used in the United States, when all DL
CCs of two different frequency bands (e.g. Band 12 and Band 14, see
FIG. 1) or when all DL CCs of a small duplex gap band are active at
the same time, potential transmit and receive intermodulation
products potentially cause intermodulation-based duplex
interference into the eNB's own receiver(s) (and potentially also
into the receivers of other networks or devices).
[0034] If (which may be an even more probable case) the different
aggregated carriers have separate RF hardware/chains,
intermodulation duplex interference is either avoided by so-called
diplexers--which are at their technical limits in case of wide LTE
channels--, or by costly additional antennas.
[0035] FIG. 1 illustrates this problem of intermodulation duplex
interference-inter-frequency band, where eNB self-interference is
caused by combining Band 12 and Band 14 on a same antenna
polarization plane, in which case a hardware-based solution (i.e.
using diplexer) can be quite challenging. However, as indicated
above, FIG. 1 only serves as an example for illustrating the
problem which is not restricted to the case of Band 12/Band 14
caused interference.
SUMMARY OF THE INVENTION
[0036] It is an object of the present invention to overcome at
least some of the drawbacks of the prior art.
[0037] According to a first aspect of the present invention, this
is accomplished by an apparatus, comprising scheduling means
configured to schedule allocation of physical downlink
communication channels to respective component carriers per time
interval according to a communication service in which
communication is performed on an aggregation of component carriers
of one or more frequency band such that component carriers to be
used for transmission are separated from component carriers to be
used for receiving by a transmit-receive-frequency gap band,
wherein the scheduling means is further configured so that not all
available component carriers to be used for transmission are
allocated in the same time interval, and wherein the scheduling
means is further configured so that, in each time interval, the
physical downlink communication channels to be allocated for
transmission are allocated to the available component carriers to
be used for transmission such that, in each frequency band, the
overall emission spectrum does not reach beyond the
transmit-receive-frequency gap band. Modifications of the first
aspect may be as follows.
[0038] The apparatus according to the first aspect may be
configured to be suitable for avoiding base station
self-interference due to transmit intermodulation in carrier
aggregated communication systems.
[0039] The physical downlink communication channels can comprise a
physical channel for broadcast communication and a primary and a
secondary synchronization channel.
[0040] The physical downlink communication channels can comprise a
physical channel configured for downlink control, and the apparatus
can further comprise radio resource control means configured to
exclude certain component carriers to be used for transmission from
having allocated the physical channel configured for downlink
control; and allocation communicating means configured to
communicate, on a component carrier which is not excluded by the
radio resource control means, information that the excluded
component carriers are not to be monitored, allocation of a
physical channel configured for shared uplink use to a component
carrier to be used for receiving and allocation of a physical
channel configured for shared downlink use to a component carrier
to be used for transmission, wherein the scheduling means can be
further configured to allocate, for consecutive time intervals, the
physical channel configured for downlink control to not excluded
component carriers to be used for transmission.
[0041] The physical downlink communication channels can comprise a
physical channel configured for hybrid automatic repeat request
indication, and the scheduling means can be further configured to
exclude those component carriers to be used for transmission from
having allocated the physical channel configured for hybrid
automatic repeat request indication which are excluded by the radio
resource control means from having allocated the physical channel
configured for downlink control.
[0042] The physical downlink communication channels can comprise a
physical control channel configured for format indication, and the
scheduling means can be further configured to exclude those
component carriers to be used for transmission from having
allocated the physical control channel configured for format
indication which are excluded by the radio resource control means
from having allocated the physical channel configured for downlink
control.
[0043] The physical downlink communication channels can comprise a
physical channel configured for shared downlink use.
[0044] The scheduling means can be further configured to apply
dynamic downlink inter-cell interference coordination.
[0045] According to a second aspect of the present invention, the
object is accomplished by an apparatus, comprising scheduling means
configured to schedule allocation of physical downlink
communication channels to respective component carriers per time
interval according to a communication service in which
communication is performed on an aggregation of component carriers
of one or more frequency band such that component carriers to be
used for transmission are separated from component carriers to be
used for receiving by a transmit-receive-frequency gap band,
wherein the scheduling means is further configured so that not all
available component carriers to be used for transmission are
allocated in the same time interval with maximum transmission
power, and wherein the scheduling means is further configured so
that, in each time interval, the physical downlink communication
channels to be allocated for transmission are allocated to the
available component carriers to be used for transmission such that,
in each frequency band, the overall emission spectrum does not
reach beyond the transmit-receive-frequency gap band.
[0046] According to a third aspect of the present invention, the
object is accomplished by an apparatus, comprising a scheduling
processor configured to schedule allocation of physical downlink
communication channels to respective component carriers per time
interval according to a communication service in which
communication is performed on an aggregation of component carriers
of one or more frequency band such that component carriers to be
used for transmission are separated from component carriers to be
used for receiving by a transmit-receive-frequency gap band,
wherein the scheduling processor is further configured so that not
all available component carriers to be used for transmission are
allocated in the same time interval, and wherein the scheduling
processor is further configured so that, in each time interval, the
physical downlink communication channels to be allocated for
transmission are allocated to the available component carriers to
be used for transmission such that, in each frequency band, the
overall emission spectrum does not reach beyond the
transmit-receive-frequency gap band.
[0047] Modifications of the third aspect of the present invention
may correspond to the modifications of the first aspect.
[0048] According to a fourth aspect of the present invention, the
object is accomplished by an apparatus, comprising a scheduling
processor configured to schedule allocation of physical downlink
communication channels to respective component carriers per time
interval according to a communication service in which
communication is performed on an aggregation of component carriers
of one or more frequency band such that component carriers to be
used for transmission are separated from component carriers to be
used for receiving by a transmit-receive-frequency gap band,
wherein the scheduling processor is further configured so that not
all available component carriers to be used for transmission are
allocated in the same time interval with maximum transmission
power, and wherein the scheduling processor is further configured
so that, in each time interval, the physical downlink communication
channels to be allocated for transmission are allocated to the
available component carriers to be used for transmission such that,
in each frequency band, the overall emission spectrum does not
reach beyond the transmit-receive-frequency gap band.
[0049] According to a fifth aspect of the present invention, the
object is accomplished by a method, comprising allocating physical
downlink communication channels to respective component carriers
per time interval according to a communication service in which
communication is performed on an aggregation of component carriers
of one or more frequency band such that component carriers to be
used for transmission are separated from component carriers to be
used for receiving by a transmit-receive-frequency gap band,
wherein not all available component carriers to be used for
transmission are allocated in the same time interval, and wherein,
in each time interval, the physical downlink communication channels
to be allocated for transmission are allocated to the available
component carriers to be used for transmission such that, in each
frequency band, the overall emission spectrum does not reach beyond
the transmit-receive-frequency gap band. Modifications of the fifth
aspect may be as follows.
[0050] The method according to the fifth aspect may be configured
to be suitable for avoiding base station self-interference due to
transmit intermodulation in carrier aggregated communication
systems.
[0051] The physical downlink communication channels can comprise a
physical channel for broadcast communication and a primary and a
secondary synchronization channel.
[0052] The physical downlink communication channels can comprise a
physical channel configured for downlink control, and the method
can further comprise excluding certain component carriers to be
used for transmission from having allocated the physical channel
configured for downlink control; communicating, on a component
carrier which is not excluded by the radio resource control means,
information that the excluded component carriers are not to be
monitored, allocation of a physical channel configured for shared
uplink use to a component carrier to be used for receiving and
allocation of a physical channel configured for shared downlink use
to a component carrier to be used for transmission; and allocating,
for consecutive time intervals, the physical channel configured for
downlink control to not excluded component carriers to be used for
transmission.
[0053] The physical downlink communication channels can comprise a
physical channel configured for hybrid automatic repeat request
indication, and the method can further comprise excluding those
component carriers to be used for transmission from having
allocated the physical channel configured for hybrid automatic
repeat request indication which are excluded from having allocated
the physical channel configured for downlink control.
[0054] The physical downlink communication channels can comprise a
physical control channel configured for format indication, and the
method can further comprise excluding those component carriers to
be used for transmission from having allocated the physical control
channel configured for format indication which are excluded from
having allocated the physical channel configured for downlink
control.
[0055] The physical downlink communication channels can comprise a
physical channel configured for shared downlink use.
[0056] The method can further comprise applying dynamic downlink
inter-cell interference coordination.
[0057] The method according to the fifth aspect or any of its
modifications may be performed by the apparatus according to the
first or third aspect or suitable ones of their modifications.
[0058] According to a sixth aspect of the present invention, the
object is accomplished by a method, comprising allocating of
physical downlink communication channels to respective component
carriers per time interval according to a communication service in
which communication is performed on an aggregation of component
carriers of one or more frequency band such that component carriers
to be used for transmission are separated from component carriers
to be used for receiving by a transmit-receive-frequency gap band,
wherein not all available component carriers to be used for
transmission are allocated in the same time interval with maximum
transmission power, and wherein, in each time interval, the
physical downlink communication channels to be allocated for
transmission are allocated to the available component carriers to
be used for transmission such that, in each frequency band, the
overall emission spectrum does not reach beyond the
transmit-receive-frequency gap band. Modifications of the sixth
aspect may be as follows.
[0059] The method according to the sixth aspect may be configured
to be suitable for avoiding base station self-interference due to
transmit intermodulation in carrier aggregated communication
systems.
[0060] The method according to the sixth aspect or any of its
modifications may be performed by the apparatus according to the
second or fourth aspect or suitable ones of their
modifications.
[0061] According to a seventh aspect of the present invention, the
object is accomplished by an evolved Node B, comprising an
apparatus according to the first to fourth aspect of the present
invention or any one of their modifications.
[0062] According to a eighth aspect of the present invention, the
object is accomplished by a computer program product comprising
computer-executable components which perform, when the program is
run on a computer, allocating physical downlink communication
channels to respective component carriers per time interval
according to a communication service in which communication is
performed on an aggregation of component carriers of one or more
frequency band such that component carriers to be used for
transmission are separated from component carriers to be used for
receiving by a transmit-receive-frequency gap band, wherein not all
available component carriers to be used for transmission are
allocated in the same time interval, and wherein, in each time
interval, the physical downlink communication channels to be
allocated for transmission are allocated to the available component
carriers to be used for transmission such that, in each frequency
band, the overall emission spectrum does not reach beyond the
transmit-receive-frequency gap band. Modifications of the eighth
aspect may be as follows.
[0063] The computer program product according to the eighth aspect
may be suitable for avoiding base station self-interference due to
transmit intermodulation in carrier aggregated communication
systems.
[0064] The computer program product according to the eighth aspect
may be embodied as a computer-readable storage medium.
[0065] Otherwise, modifications of the eighth aspect may correspond
to the modifications of the fifth aspect.
[0066] According to a ninth aspect of the present invention, the
object is accomplished by a computer program product comprising
computer-executable components which perform, when the program is
run on a computer, allocating of physical downlink communication
channels to respective component carriers per time interval
according to a communication service in which communication is
performed on an aggregation of component carriers of one or more
frequency band such that component carriers to be used for
transmission are separated from component carriers to be used for
receiving by a transmit-receive-frequency gap band, wherein not all
available component carriers to be used for transmission are
allocated in the same time interval with maximum transmission
power, and wherein, in each time interval, the physical downlink
communication channels to be allocated for transmission are
allocated to the available component carriers to be used for
transmission such that, in each frequency band, the overall
emission spectrum does not reach beyond the
transmit-receive-frequency gap band. Modifications of the ninth
aspect may be as follows.
[0067] The computer program product according to the ninth aspect
may be suitable for avoiding base station self-interference due to
transmit intermodulation in carrier aggregated communication
systems.
[0068] The computer program product according to the ninth aspect
may be embodied as a computer-readable storage medium.
[0069] Otherwise, modifications of the ninth aspect may correspond
to the modifications of the sixth aspect.
[0070] It is to be understood that any of the above modifications
can be applied singly or in combination to the respective aspects
to which they refer, unless they are explicitly stated as excluding
alternatives.
BRIEF DESCRIPTION OF THE DRAWINGS
[0071] The above and other objects, features, details and
advantages will become more fully apparent from the following
detailed description of the preferred embodiments which is to be
taken in conjunction with the appended drawings, in which:
[0072] FIG. 1 illustrates the problem of intermodulation duplex
interference-inter-frequency band;
[0073] FIG. 2 illustrates frequency ranges of intermodulation
effects of PDCCH, PBCH/synchronization channels, and fully
allocated PDSCH;
[0074] FIG. 3 shows a possible time shift for eliminating conflicts
of PBCH and synchronization channels between component carriers and
component carriers of different frequency bands;
[0075] FIG. 4 shows the time-multiplexed muting of PBCH and
synchronization channels according to certain embodiments of the
present invention;
[0076] FIG. 5 shows the time-multiplexed configuration of
PDCCH/PHICH/PCFICH in the first (three) OFDM symbols (combined with
the time-multiplexed muting of PBCH and synchronization channels
according to FIG. 3) according to certain embodiments of the
present invention;
[0077] FIG. 6 shows the cross-CC scheduling adhering to DL CC PDSCH
time-multiplexing rules according to certain embodiments of the
present invention;
[0078] FIG. 7 shows an apparatus according to certain embodiments
of the present invention; and
[0079] FIG. 8 shows a flow chart illustrating a method according to
certain embodiments of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0080] In the following, description is made to what are presently
considered to be preferred embodiments of the present invention. It
is to be understood, however, that the description is given by way
of example only, and that the described embodiments are by no means
to be understood as limiting the present invention thereto.
[0081] For example, for illustration purposes, in some of the
following exemplary embodiments, avoidance of self-interference due
to transmitter intermodulation in carrier aggregated communication
systems such as e.g. based on LTE-Advanced is described. However,
it should be appreciated that these exemplary embodiments are not
limited for use among these particular types of wireless
communication systems, and according to further exemplary
embodiments, the present invention can be applied also to other
types of communication systems and access networks in which the
problem of self-interference due to transmitter intermodulation
occurs.
[0082] Thus, certain embodiments of the present invention relate to
mobile wireless communication systems, such as 3GPP LTE and 3GPP
LTE-Advanced. In more detail, certain embodiments of the present
invention are related to the configuration of an LTE eNB and
components thereof, such as a scheduler element or the like.
[0083] However, as indicated above, the present invention is not
limited to eNB, but other embodiments of the present invention are
related to base station nodes and components thereof.
[0084] FIG. 7 shows a principle configuration of an example for an
apparatus according to certain embodiments of the present
invention. One option for implementing this example for an
apparatus according to certain embodiments of the present invention
would be a component such as a scheduler in an evolved Node B
according to LTE.
[0085] Specifically, as shown in FIG. 7, the example for an
apparatus comprises a scheduling processor 71 configured to
schedule allocation of physical downlink communication channels to
respective component carriers per time interval according to a
communication service in which communication is performed on an
aggregation of component carriers of one or more frequency band
such that component carriers to be used for transmission are
separated from component carriers to be used for receiving by a
transmit-receive-frequency gap band, wherein the scheduling
processor is further configured so that not all available component
carriers to be used for transmission are allocated in the same time
interval, and wherein the scheduling processor is further
configured so that, in each time interval, the physical downlink
communication channels to be allocated for transmission are
allocated to the available component carriers to be used for
transmission such that, in each frequency band, the overall
emission spectrum does not reach beyond the
transmit-receive-frequency gap band.
[0086] According to needs, modifications of the above described
apparatus may include that additionally a radio resource control
processor 72, an allocation communication processor 73, and a
transmit power control processor 74 are included, either
alternatively or in any combination.
[0087] FIG. 8 shows a principle flowchart of an example for a
method according to certain embodiments of the present invention.
That is, as shown in FIG. 8, this method comprises allocating (S1)
physical downlink communication channels to respective component
carriers per time interval according to a communication service in
which communication is performed on an aggregation of component
carriers of one or more frequency band such that component carriers
to be used for transmission are separated from component carriers
to be used for receiving by a transmit-receive-frequency gap band
(which effectively may include that the available component
carriers to be used for transmission are determined), wherein not
all available component carriers to be used for transmission are
allocated (S2) in the same time interval, and wherein, in each time
interval, the physical downlink communication channels to be
allocated for transmission are allocated (S3) to the available
component carriers to be used for transmission such that, in each
frequency band, the overall emission spectrum does not reach beyond
the transmit-receive-frequency gap band.
[0088] As a modification, instead of not at all allocating an
available component carrier to be used for transmission, such
available component carrier to be used for transmission may be
allocated, but with a suitable lower than maximum transmission
power.
[0089] One option for performing the example of a method according
to certain embodiments of the present invention would be to use the
apparatus as described above or a modification thereof which
becomes apparent from the embodiments as described herein
below.
[0090] According to certain embodiments of the present invention,
both the above described apparatus as well as the above described
method cam be implemented such that the set of used transmit
component carriers is optimized with respect to the overall
emission spectrum. That is, the physical downlink communication
channels to be allocated for transmission are allocated to the
available component carriers to be used for transmission such that
the overall emission spectrum does not reach beyond the
transmit-receive-frequency gap band. The term "does not reach
beyond the transmit-receive-frequency gap band" is to be understood
such that any receiving unit configured for receiving a frequency
band beyond this gap is not negatively affected. As a receiving
unit, for example a receiver unit of an eNB according to the
LTE/LTE-Advanced specifications may be taken. In many cases, the
above may be achieved if the physical downlink communication
channels to be allocated for transmission are allocated to the
available component carriers to be used for transmission such that
in each frequency band, the set of used component carriers is as
far as possible from a transmit-receive-frequency gap band, for
example regardless of how many component carriers are actually to
be used (while still complying with the premise that not all
available component carriers to be used for transmission are
allocated in the same time interval).
[0091] In the following, for illustration purposes, certain
embodiments of the present invention are described by referring to
the wide downlink component carrier area of the lower and upper 700
MHz frequency band (Band 12/Band 14) as e.g. used in the United
States. However, the present invention is by no means limited to
these frequency bands and may be applied to other examples of
carrier aggregation as well.
[0092] Furthermore, certain embodiments of the present invention
may be used in addition to measures proposed in the prior art such
as a hardware based solution.
[0093] Specifically, according to certain embodiments of the
present invention, intermodulation-caused eNB self-interference is
dynamically or semi-statically avoided by combining various
time-multiplexing muting and cross-CC scheduling steps
differentiated with respect to different channels on the physical
layer on an otherwise backward-compatible carrier.
[0094] Accordingly, communication may be performed on an
aggregation of at least two component carriers of one or more
frequency bands in such a way that potential intermodulation
interference into the receive spectrum portions--caused by a
reverse alignment of transmission and receive spectrum portions of
at least two frequency bands or by a small duplex gap in at least
one frequency band or by a combination of both or by neighboring
FDD and TDD spectrum portions--is avoided.
[0095] According to certain embodiments of the present invention,
it is considered that the dominant cause for duplex interference
are 3rd order (and to some extend 5th order) intermodulation
products. Hence, limiting the frequency range of 3rd order (and
potentially of 5th order) intermodulation products will in these
cases significantly lower the receiver desensitization due to
duplex interference.
[0096] To illustrate, FIG. 2 shows the frequency ranges of
intermodulation effects of PDCCH, PBCH and synchronization
channels, and fully allocated PDSCH.
[0097] In the following, according to certain embodiments of the
present invention, by referring to these different channels, the
various time-multiplexing muting and cross-CC scheduling steps
pertaining to such certain embodiments are described in detail.
PBCH and Synchronization Channels
[0098] In order to mitigate the time-domain transmit conflict on
the physical broadcast channel (PBCH) as well as the primary and
secondary synchronization signals, a synchronous time shift of
sub-frame numbering (SFN) of multiples of 1 ms but excluding
multiples of 5 ms can be provided.
[0099] FIG. 3 shows an example of such a possible time shift
configuration for eliminating conflicts of PBCH and synchronization
channels between component carriers and component carriers of
different frequency bands.
[0100] Alternatively or in addition thereto, the PBCH and
synchronization channels are muted in a time-multiplexed
manner.
[0101] Specifically, the PBCH and the primary and secondary
synchronization channels are time-multiplexed muted following a
pattern that limits the range of 3rd order and potentially 5th
order intermodulation interference to the duplex gap.
[0102] FIG. 4 shows an example for such a pattern with which a
significantly reduced intermodulation duplex interference range is
obtained (filled bars). The intermodulation duplex interference due
to PBCH and primary/secondary synchronization channels does not
reach the eNB receiver spectrum anymore.
PDCCH
[0103] As for LTE-Advanced carrier aggregation a synchronous
operation is required, wherein OFDM symbols are synchronized down
to a fraction of the cyclic prefix and first OFDM symbol are
synchronized within a TTI such that PDCCH OFDM symbols are aligned,
the mutually exclusive presence of PDCCH in a line of DL CCs will
allow for limiting the range of 3rd order (and 5th order)
intermodulation products and hence eliminating (reducing) duplex
interference.
[0104] In detail, this can be achieved by configuring the PDCCH
monitoring sets of all UEs via RRC connection reconfiguration not
to contain those DL CCs that are selected not to carry any PDCCH.
As a consequence, the PDSCH of this DL CC is allocated through
cross-CC scheduling from a DL CC which belongs to all the PDCCH
monitoring sets.
[0105] Analogously, the UL CC PUSCH is allocated through cross-CC
scheduling from a DL CC which belongs to all the PDCCH monitoring
sets.
[0106] As the PDCCH capacity demand on the other DL CCs which are
present in all PDCCH monitoring sets of the UEs consequently
increases, the network is configured with three OFDM symbols for
PDCCH on all DL CCs.
[0107] As a result, there are two cases concerning the first three
OFDM symbols of a TTI:
[0108] Either, the eNB does not transmit on the first three OFDM
symbols of a TTI of DL CC's selected not to carry PDCCH. This
limits the range of the 3rd order intermodulation products for the
first three OFDM symbols in a TTI (see FIG. 5).
[0109] Or, instead, a known optimization could allocate PDSCH on
the first three OFDM symbols of the TTI.
[0110] As a consequence of the time-multiplexed configuration of
PDCCH monitoring sets, also the PHICH is made subject to a
time-multiplexed configuration.
[0111] For those DL CCs that are being operated without any PDCCH,
there is no need to provide PHICH resources as no UL grant can
origin from this DL CC and as a consequence no PHICH resources are
required on this DL CC.
[0112] When eliminating a DL CC from the PDCCH monitoring sets of
all RRC connected UEs according to release 10, all acknowledge/not
acknowledge signaling in the PHICH is set to acknowledge thereby
performing a hard termination of all UL HARQ processes. Faults
introduced due to this hard termination are repaired by the higher
layer ARQ.
[0113] A graceful withdrawal of the control channels from the DL CC
requires completing the UL HARQ processes. As the UL HARQ process
is synchronous, the eNB is capable of exactly planning the number
of TTIs the completion will take. As the completion period will
last in the order of 50 ms to 100 ms, a corresponding period of
time must be waited before setting up control channels in another
DL CC as otherwise intermodulation interference may be generated
during PDCCH monitoring set reconfigurations.
[0114] While reconfiguring release 10 UEs, release 8 UEs are
handed-over to a carrier maintaining the DL control channels.
Termination and completion of HARQ and ARQ processes then follow
LTE release 8 principles.
[0115] As a further consequence of the time-multiplexed
configuration of PDCCH monitoring sets, also the PCFICH is made
subject to a time-multiplexed muting.
[0116] Specifically, the PCFICH information is required in order to
know in which OFDM symbol the allocation of the PDSCH transport
block starts. In detail, the UE gets the information that the first
three OFDM symbols would have been allocated for PDCCH from the
PCFICH of the DL CC that contains the cross-CC scheduled DL grant.
As all UEs are configured with the same PDCCH monitoring sets at a
given time, the PCFICH information of those DL CCs selected not to
be part of the PDCCH monitoring sets is not needed and can be
muted.
[0117] FIG. 5 shows examples of shortened intermodulation duplex
interference ranges of the PDCCH/PHICH/PCFICH channels (hatched
bars). That is, FIG. 5 shows the time-multiplexed configuration of
PDCCH/PHICH/PCFICH in the first (three) OFDM symbols (combined with
the time-multiplexed muting of PBCH/synchronization channels, see
PBCH section above).
PDSCH
[0118] For the intermodulation range limitation of the PDSCH it is
possible to perform a cross-CC scheduling of DL CCs
time-multiplexed and/or reduced transmit power aware.
[0119] Specifically, if the DL transmission of multiple frequency
bands are combined on the same antenna (as for example in the case
of Band 12 and Band 14 in the U.S.), a direct method of avoiding
the intermodulation duplex interference range due to PDSCH channels
can be achieved as follows:
[0120] FIG. 6 shows for a given PDCCH monitoring sets configuration
(see PDCCH section above), and a given PBCH/synchronization channel
muting (see PCH section above), examples of suitable PDSCH
allocations with limited intermodulation duplex interference range.
A cross-CC PDSCH scheduling such as e.g. illustrated in FIG. 6,
while adhering to a DL CC PDSCH time-multiplexing rule that at any
given time the transmission configuration resulting from scheduling
configuration and muting must be such that the intermodulation
interference range does NOT "reach"/affect any receive spectrum
portion, provides allocation freedom e.g. with respect to peak DL
data rates or UE frequency band capabilities and protects the eNB
receiver(s) at the same time.
[0121] The above shown allocation schemes are modified in CC
granularity, i.e. in a given TTI or time period, Where either the
PDSCH of a DL CC is used in full bandwidth or not used at all.
Until now, it has also been assumed that the DL CC is always used
at maximum eNB transmit power.
[0122] In the following section a variation of the intermodulation
interference avoiding scheduling based on transmit power profiles
is described.
[0123] That is, as an alternative to the above, the
time-multiplexing rule can be amended or substituted by DL CC
transmit power profiles. For example, the eNB does not transmit at
maximum power on DL CCs close to the eNB duplex gap. Cross-CC
scheduling will instead optimize PDSCH allocations with respect to
UE path loss such that allocations containing a DL CC with low
transmit power are reserved for UEs with little path loss and good
radio conditions while allocations on DL CCs with high or maximum
eNB transmit power are reserved for UEs with high path loss and bad
radio conditions.
[0124] Still further, another alternative is represented by a
further application of cross-CC PDSCH scheduling while adhering to
the DL CC time-multiplexing rule comprising dynamic DL inter-cell
interference coordination (DL ICIC).
[0125] As described above, certain embodiments of the present
invention relate to an apparatus, method, system and computer
program product which is configured for avoiding base station
self-interference due to transmit intermodulation in carrier
aggregated communication systems. Physical downlink communication
channels are allocated to respective component carriers per time
interval according to a communication service in which
communication is performed on an aggregation of component carriers
of one or more frequency band such that component carriers to be
used for transmission are separated from component carriers to be
used for receiving by a transmit-receive-frequency gap band.
However, not all available component carriers to be used for
transmission are allocated in the same time interval. Rather, in
each time interval, the physical downlink communication channels to
be allocated for transmission are allocated to the available
component carriers to be used for transmission such that, in each
frequency band, the overall emission spectrum does not reach beyond
the transmit-receive-frequency gap band.
[0126] As further indicated above, implementations examples for
certain embodiments of the present invention include base station
equipment capable of carrier aggregation handling such as
LTE/LTE-Advanced eNB, but are not limited thereto.
[0127] According to the above description, it should thus be
apparent that exemplary embodiments of the present invention
provide, for example from the perspective of a network element such
as an evolved Node B (eNB) or a component thereof, an apparatus
embodying the same, a method for controlling and/or operating the
same, and computer program(s) controlling and/or operating the same
as well as mediums carrying such computer program(s) and forming
computer program product(s).
[0128] For example, described above are apparatuses, methods and
computer program products capable of avoiding base station
self-interference due to transmit intermodulation in carrier
aggregated communication systems.
[0129] Implementations of any of the above described blocks,
apparatuses, systems, techniques or methods include, as non
limiting examples, implementations as hardware, software, for
example in connection with a digital signal processor, firmware,
special purpose circuits or logic, general purpose hardware or
controller or other computing devices, or some combination
thereof.
[0130] What is described above is what is presently considered to
be preferred embodiments of the present invention. However, as is
apparent to the skilled reader, these are provided for illustrative
purposes only and are in no way intended that the present invention
is restricted thereto. Rather, it is the intention that all
variations and modifications be included which fall within the
spirit and scope of the appended claims.
* * * * *