U.S. patent application number 14/484272 was filed with the patent office on 2015-04-09 for method, base station, and user equipment for transmitting downlink control signal.
This patent application is currently assigned to Huawei Device Co.,Ltd.. The applicant listed for this patent is Huawei Device Co.,Ltd.. Invention is credited to Chi GAO, Yingyang LI.
Application Number | 20150098409 14/484272 |
Document ID | / |
Family ID | 49137440 |
Filed Date | 2015-04-09 |
United States Patent
Application |
20150098409 |
Kind Code |
A1 |
LI; Yingyang ; et
al. |
April 9, 2015 |
METHOD, BASE STATION, AND USER EQUIPMENT FOR TRANSMITTING DOWNLINK
CONTROL SIGNAL
Abstract
The application pertains to a method for transmitting a downlink
control signal. A base station maps an enhanced physical downlink
control channel (E-PDCCH) sequentially to resource elements for
transmitting the E-PDCCH in each orthogonal frequency division
multiplexing (OFDM) symbol according to an order of OFDM symbols
used by the E-PDCCH of a user equipment (UE). The E-PDCCH is sent
to the UE from the base station by using the resource elements,
where the E-PDCCH and a physical downlink shared channel (PDSCH)
invoked by the E-PDCCH are frequency-division multiplexed. Because
the E-PDCCH is mapped sequentially to resource elements for
transmitting the E-PDCCH in each OFDM symbol according to an order
of OFDM symbols used by the E-PDCCH of the UE, different control
channel elements of E-PDCCHs at different aggregation levels will
not include a same E-PDCCH modulation symbol, thereby ensuring that
the UE judges a start position of the E-PDCCH correctly.
Inventors: |
LI; Yingyang; (Shenzhen,
CN) ; GAO; Chi; (Beijing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Huawei Device Co.,Ltd. |
Shenzhen |
|
CN |
|
|
Assignee: |
Huawei Device Co.,Ltd.
Shenzhen
CN
|
Family ID: |
49137440 |
Appl. No.: |
14/484272 |
Filed: |
September 12, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/CN2012/079446 |
Jul 31, 2012 |
|
|
|
14484272 |
|
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Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04L 5/06 20130101; H04W
72/0453 20130101; H04L 5/0044 20130101; H04L 5/0053 20130101; H04W
28/065 20130101; H04W 72/04 20130101; H04L 27/2601 20130101; H04W
72/042 20130101 |
Class at
Publication: |
370/329 |
International
Class: |
H04W 72/04 20060101
H04W072/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 16, 2012 |
CN |
201210070953.6 |
Claims
1-68. (canceled)
69. A method for transmitting a downlink control signal,
comprising: mapping, by a base station, an enhanced physical
downlink control channel (E-PDCCH) of a user equipment (UE)
sequentially to resource elements for transmitting the E-PDCCH in
each orthogonal frequency division multiplexing (OFDM) symbol
according to an order of the OFDM symbols used by the E-PDCCH of
the UE; and sending, by the base station, the E-PDCCH to the UE by
using the mapped resource elements; wherein the E-PDCCH and a
physical downlink shared channel (PDSCH) invoked by the E-PDCCH are
frequency-division multiplexed.
70. The method according to claim 69, wherein mapping the E-PDCCH
sequentially to the resource elements comprises: mapping the
E-PDCCH sequentially to resource elements occupied by L control
channel elements in each OFDM symbol according to an order of the L
control channel elements allocated to the E-PDCCH in the OFDM
symbol, wherein L is an integer.
71. The method according to claim 70, wherein mapping the E-PDCCH
sequentially to the resource elements occupied by the L control
channel elements in each OFDM symbol comprises: mapping modulation
symbols of the E-PDCCH with index numbers of j 0 + q = 0 l - 1 N q
+ [ 0 , , N l - 1 ] ##EQU00009## sequentially to a set R.sub.l of
resource elements, wherein the set R.sub.l is a set of resource
elements occupied by the l.sup.th control channel element among the
L control channel elements comprised in the E-PDCCH in the OFDM
symbol; j.sub.0 is a start position of the modulation symbols of
the E-PDCCH mapped in the OFDM symbol; N.sub.l is the quantity of
the resource elements in the set R.sub.l; and N.sub.l, j.sub.0, l
and q are integers.
72. The method according to claim 69, wherein mapping the E-PDCCH
sequentially to the resource elements comprises: mapping the
E-PDCCH sequentially to resource elements occupied by L control
channel elements allocated to the E-PDCCH according to an order of
subcarriers in each OFDM symbol, wherein L is an integer.
73. The method according to claim 72, wherein mapping the E-PDCCH
sequentially to the resource elements occupied by L control channel
elements allocated to the E-PDCCH comprises: mapping modulation
symbols of the E-PDCCH with index numbers of j.sub.0+[0, . . . ,
N-1] sequentially to a set R of resource elements, wherein j.sub.0
is a start position of the modulation symbols of the E-PDCCH mapped
in the OFDM symbol; the set R is a set of resource elements
occupied by the L control channel elements comprised in the E-PDCCH
in the OFDM symbol; N is the quantity of the resource elements in
the set R; and N and j.sub.0 are integers.
74. A method for receiving a downlink control signal, comprising:
receiving, by a user equipment (UE), a downlink subframe from a
base station; extracting, by the UE, modulation symbols of a
candidate enhanced physical downlink control channel (E-PDCCH)
sequentially from resource elements mapped to the candidate E-PDCCH
in each orthogonal frequency division multiplexing (OFDM) symbol
according to an order of the OFDM symbols used by the candidate
E-PDCCH in the downlink subframe; and performing a decoding and a
cyclic redundancy check (CRC) on the candidate E-PDCCH; wherein the
E-PDCCH of the UE and a physical downlink shared channel (PDSCH)
invoked by the E-PDCCH of the UE are frequency-division
multiplexed.
75. The method according to claim 74, wherein extracting the
modulation symbols of the candidate E-PDCCH comprises: extracting
the modulation symbols of the candidate E-PDCCH sequentially from
resource elements occupied by L control channel elements in each
OFDM symbol according to an order of the L control channel elements
allocated to the E-PDCCH in the OFDM symbol, wherein L is an
integer.
76. The method according to claim 75, wherein extracting the
modulation symbols of the candidate E-PDCCH sequentially from
resource elements occupied by the L control channel elements in
each OFDM symbol comprises: extracting modulation symbols of the
candidate E-PDCCH and with index numbers of j 0 + q = 0 l - 1 N q +
[ 0 , , N l - 1 ] ##EQU00010## from a set R.sub.l of resource
elements, wherein the set R.sub.l is a set of resource elements
occupied by the l.sup.th control channel element among the L
control channel elements comprised in the modulation symbols of the
candidate E-PDCCH in the OFDM symbol; j.sub.0 is a start position
of the modulation symbols of the candidate E-PDCCH mapped in the
OFDM symbol; N.sub.l is the quantity of the resource elements in
the set R.sub.l; and N.sub.l, j.sub.0, l and q are integers.
77. The method according to claim 74, wherein extracting the
modulation symbols of the candidate E-PDCCH comprises: extracting,
by the UE, the modulation symbols of the candidate E-PDCCH from
resource elements occupied by L control channel elements allocated
to the candidate E-PDCCH according to an order of subcarriers in
each OFDM symbol.
78. The method according to claim 77, wherein extracting the
modulation symbols of the candidate E-PDCCH from resource elements
occupied by L control channel elements allocated to the candidate
E-PDCCH comprises: extracting modulation symbols of the candidate
E-PDCCH and with index numbers of j.sub.0+[0, . . . , N-1] from a
set R of resource elements, wherein j.sub.0 is a start position of
the modulation symbols of the candidate E-PDCCH mapped in the OFDM
symbol; the set R is a set of resource elements occupied by the L
control channel elements comprised in the modulation symbols of the
candidate E-PDCCH in the OFDM symbol; N is the quantity of the
resource elements in the set R; and N and j.sub.0 are integers.
79. A base station, comprising: a mapping processor, configured to
map an enhanced physical downlink control channel (E-PDCCH) of a
user equipment (UE) sequentially to resource elements for
transmitting the E-PDCCH in each orthogonal frequency division
multiplexing (OFDM) symbol according to an order of the OFDM
symbols used by the E-PDCCH of the UE; and a transmitter,
configured to send the E-PDCCH to the UE by using the mapped
resource elements; wherein the E-PDCCH and a physical downlink
shared channel (PDSCH) invoked by the E-PDCCH are
frequency-division multiplexed.
80. The base station according to claim 79, wherein the mapping
processor maps the E-PDCCH sequentially to resource elements
occupied by L control channel elements in each OFDM symbol
according to an order of the L control channel elements allocated
to the E-PDCCH in the OFDM symbol, wherein L is an integer.
81. The base station according to claim 79, wherein the mapping
processor maps the E-PDCCH sequentially to resource elements
occupied by L control channel elements allocated to the E-PDCCH
according to an order of subcarriers in each OFDM symbol.
82. A user equipment, comprising: a receiver, configured to receive
a downlink subframe from a base station; and an extracting
processor, configured to sequentially extract modulation symbols of
a candidate enhanced physical downlink control channel (E-PDCCH)
sequentially from resource elements mapped to the candidate E-PDCCH
in each orthogonal frequency division multiplexing (OFDM) symbol
according to an order of the OFDM symbols used by the candidate
E-PDCCH in the downlink subframe, and perform a decoding and a
cyclic redundancy check (CRC) on the candidate E-PDCCH; wherein an
E-PDCCH of the user equipment and a physical downlink shared
channel (PDSCH) invoked by the E-PDCCH of the user equipment are
frequency-division multiplexed.
83. The user equipment according to claim 82, wherein the
extracting processor extracts the candidate E-PDCCH sequentially
from resource elements occupied by L control channel elements in
each OFDM symbol according to an order of the L control channel
elements allocated to the candidate E-PDCCH in the OFDM symbol,
wherein L is an integer.
84. The user equipment according to claim 82, wherein the
extracting processor extracts the modulation symbols of the
candidate E-PDCCH from resource elements occupied by L control
channel elements allocated to the candidate E-PDCCH according to an
order of subcarriers in each OFDM symbol.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to Chinese Patent
Application No. 201210070953.6, filed with the Chinese Patent
Office on Mar. 16, 2012, and entitled "METHOD, BASE STATION, AND
USER EQUIPMENT FOR TRANSMITTING DOWNLINK CONTROL SIGNAL", which is
incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] Embodiments of the present invention relate to the field of
communications technologies, and in particular, to a method, a base
station, and a user equipment for transmitting a downlink control
signal.
BACKGROUND
[0003] In a 3GPP (3.sup.rd Generation Partnership Project) LTE
(Long Term Evolution)/LTE-A (LTE-advanced) system, a downlink
multiple access mode generally used is an OFDMA (Orthogonal
Frequency Division Multiple Access) mode. In terms of time,
downlink resources of the system are divided into OFDM (Orthogonal
Frequency Division Multiplexing) symbols, and in terms of
frequency, the downlink resources of the system are divided into
subcarriers.
[0004] In LTE release 8, LTE release 9 and LTE release 10, one
downlink subframe includes two timeslots, and each timeslot
includes 7 or 6 OFDM symbols, so that a downlink subframe includes
14 or 12 OFDM symbols. One PRB (Physical Resource Block) includes
12 subcarriers in a frequency domain, and one timeslot in a time
domain, which means that one PRB includes 7 or 6 OFDM symbols. A
subcarrier in an OFDM symbol is called a Resource Element (RE), and
therefore one PRB includes 84 or 72 REs. In one subframe, two PRBs
of two timeslots at a same frequency position are called a physical
resource block pair; and in LTE, a resource granularity of downlink
transmission is a physical resource block (PRB) pair.
[0005] In LTE release 10 and earlier LTE systems, a physical
downlink control channel (PDCCH) and a physical downlink shared
channel (PDSCH) are time-division multiplexed in one subframe. The
PDCCH is borne on the first n symbols of a subframe, and downlink
data that the PDCCH schedules is mapped from the (n+1).sup.th
symbol of the subframe. In one subframe, all PDCCHs scheduling user
equipments (UEs) are multiplexed together, and are then sent in a
PDCCH area. One PDCCH may be formed by 1, 2, 4 or 8 control channel
elements (CCEs); one CCE is formed by 9 resource element groups
(REGs); and one REG occupies 4 REs.
[0006] In LTE release 10 and earlier LTE systems, according to an
index of the first CCE of a downlink grant (DL_grant) for
scheduling a UE, that is, a start position of an enhanced physical
downlink control channel E-PDCCH (Enhanced PDCCH), a physical
uplink control channel (PUCCH) format 1a/1b channel may be
determined in an implicit manner to bear ACK/NACK
(Acknowledgement/Negative-acknowledgement) feedback information for
downlink data transmission.
[0007] As control information in a PDCCH is obtained by means of
convolutional encoding with master code being 1/3 and circular
buffering based rate matching, when an encoding rate is less than
1/3, it may occur that different CCEs include a same modulation
symbol. For example, when the PDCCH is formed by 4 CCEs, each
including 72 bits, the PDCCH can carry totally 288 encoded bits.
Assuming that the PDCCH originally has 48 bits, the bit number
becomes 144 after the 1/3 encoding, and becomes 288 after the
circular buffering based rate matching, which is equivalent to a
repetition encoding; and the 288 bits are finally mapped to the
four CCEs of the PDCCH. Therefore, modulation symbols in the third
CCE and the fourth CCE are completely the same as modulation
symbols in the first CCE and the second CCE.
[0008] Under the foregoing situation, a base station sends a PDCCH
at aggregation level (AL) 4, but when performing blind detection, a
UE may possibly detect information in the third CCE and the fourth
CCE as a PDCCH at aggregation level 2. Therefore, the UE may
determine a PUCCH format 1a/1b channel in an implicit manner
according to an index of the first CCE of the PDCCH at aggregation
level 2, that is, an index of the third CCE. However, the base
station may regard that the PUCCH format 1a/1b channel allocated to
the UE is determined by the first CCE, so that feedback information
cannot be correctly transmitted. It can be seen that unclearness of
the CCE detection (that is, incorrect judgment on the start
position of the E-PDCCH) will lead to unclearness of the PUCCH
format 1a/1b channel determined by the UE.
[0009] In a LTE system later than release 10, with introduction of
a multi-user multi-input multi-output antenna system (MIMO antenna
system) and coordinated multi-point (CoMP) transmission and like
technologies, a control channel capacity is restricted. Therefore,
a PDCCH, which is transmitted based on a MIMO pre-coding mode is
introduced and the PDCCH can be demodulated based on a UE-specific
reference signal, that is, a demodulation reference signal (DMRS),
and the PDCCH here is also called an E-PDCCH. An E-PDCCH is not in
a control area of the first n symbols of a subframe, but is in a
downlink data transmission area of the subframe, and is
frequency-division multiplexed with a PDSCH, and may occupy a
different PRB pair from that occupied by the PDSCH, or an E-PDCCH
and a PDSCH may be multiplexed in a same PRB pair. In addition, a
group of PRB pairs for E-PDCCH(s) may be configured for a cell, so
that each UE in the cell knows all the PRB pairs for E-PDCCH(s)
that are configured by a base station; or, a PRB pair for E-PDCCH
transmission may be configured for each UE, which means that PRB
pairs for E-PDCCHs that different UEs need to detect may be
different.
[0010] Using LTE release 11 as an example, a reference signal of an
E-PDCCH is a UE-specific reference signal, and can support 4 ports
(that is, DMRS ports 7, 8, 9 and 10 for PDSCH demodulation in LTE
release 10). A data part of an E-PDCCH is used to bear modulation
symbols of control information after coding and modulation.
[0011] An E-PDCCH CCE, hereinafter called an eCCE, is also defined
in LTE release 11. Using a localized E-PDCCH as an example, there
are many REs that can be used to transmit an E-PDCCH in a PRB pair,
and these REs may further be divided into several eCCEs. An E-PDCCH
is formed by one or more eCCEs by means of aggregation, and needs
to be blindly detected by a UE. As control information in the
E-PDCCH is also obtained by means of convolutional encoding with
master code being 1/3 and circular buffering based rate matching, a
problem also exists that a UE judges a start position of the
E-PDCCH incorrectly.
SUMMARY
[0012] Embodiments of the present invention provide a method, a
base station, and a user equipment for transmitting a downlink
control signal, that a UE judging a start position of an E-PDCCH
incorrectly can be avoided.
[0013] According to one aspect, a method for transmitting a
downlink control signal is provided, including: mapping, by a base
station according to an order of OFDM symbols used by a physical
downlink control channel E-PDCCH of a user equipment UE, the
E-PDCCH sequentially to resource elements used to transmit the
E-PDCCH in each OFDM symbol; and sending, by the base station, the
E-PDCCH to the UE by using the resource elements.
[0014] According to another aspect, a method for transmitting a
downlink control signal is provided, including: receiving, by a
user equipment UE, a downlink subframe from a base station; and
extracting, by the UE in a blind detection process according to an
order of OFDM symbols used by a candidate E-PDCCH in the downlink
subframe, modulation symbols of the candidate E-PDCCH sequentially
from resource elements used to transmit the candidate E-PDCCH in
each OFDM symbol, and performing decoding and cyclic redundancy
check CRC on the candidate E-PDCCH.
[0015] According to another aspect, a method for transmitting a
downlink control signal is provided, including: determining, by a
base station, a reference signal port according to an aggregation
level of a physical downlink control channel E-PDCCH of a user
equipment UE, where E-PDCCHs at different aggregation levels
correspond to different reference signal ports, and the aggregation
level indicates the quantity of control channel elements included
in the E-PDCCH; and sending, by the base station, the E-PDCCH to
the UE in a subframe, and sending a reference signal of the E-PDCCH
to the UE by using the determined reference signal port.
[0016] According to another aspect, a method for transmitting a
downlink control signal is provided, including: receiving, by a
user equipment UE from a reference signal port in a subframe, a
reference signal of a candidate E-PDCCH sent by a base station,
where candidate E-PDCCHs at different aggregation levels correspond
to different reference signal ports, and the aggregation level
indicates the quantity of control channel elements included in the
candidate E-PDCCH; and performing, by the UE, channel estimation
according to the reference signal, so as to demodulate the
candidate E-PDCCH.
[0017] According to another aspect, a method for transmitting a
downlink control signal is provided, including: sending, by a base
station, a reference signal of the E-PDCCH by using a first
reference signal port v; sending, by the base station, a reference
signal of the PDSCH by using at least one second reference signal
port; and determining, by the base station, not to use a second
reference signal port p(v) to send the reference signal of the
PDSCH, so that a reference signal port of the E-PDCCH and a
reference signal port of the PDSCH are processed based on
orthogonal time extensions with different lengths, where the first
reference signal port is one of the at least one second reference
signal port, and v and p(v) are serial numbers of the reference
signal ports.
[0018] According to another aspect, a method for transmitting a
signal is provided, including: receiving, by a user equipment UE, a
reference signal of a physical downlink control channel E-PDCCH
which is sent by a base station by using a first reference signal
port v and a reference signal of a physical downlink shared channel
PDSCH which is sent by the base station by using at least one
second reference signal port, where the PDSCH is invoked by the
E-PDCCH; performing, by the UE, channel estimation by using the
reference signal of the E-PDCCH, so as to demodulate the E-PDCCH,
and performing channel estimation by using the reference signal of
the PDSCH, so as to demodulate the PDSCH; and determining, by the
UE, not to use a reference signal of the PDSCH sent by a second
reference signal port p(v) to perform channel estimation, so that a
reference signal port of the E-PDCCH and a reference signal port of
the PDSCH are processed based on orthogonal time extensions with
different lengths, where the first reference signal port is one of
the at least one second reference signal port, and v and p(v) are
serial numbers of the reference signal ports.
[0019] According to another aspect, a base station is provided,
including: a mapping unit, configured to map, according to an order
of OFDM symbols used by a physical downlink control channel E-PDCCH
of a user equipment UE, the E-PDCCH sequentially to resource
elements used to transmit the E-PDCCH in each OFDM symbol; and a
sending unit, configured to send the E-PDCCH to the UE by using the
resource elements.
[0020] According to another aspect, a user equipment is provided,
including: a receiving unit, configured to receive a downlink
subframe from a base station; and an extracting unit, configured to
extract, in a blind detection process according to an order of OFDM
symbols used by a candidate E-PDCCH in the downlink subframe,
modulation symbols of the candidate E-PDCCH sequentially from
resource elements used to transmit the candidate E-PDCCH in each
OFDM symbol, and perform decoding and CRC check on the candidate
E-PDCCH.
[0021] According to another aspect, a base station is provided,
including: a determining unit, configured to determine a reference
signal port according to an aggregation level of a physical
downlink control channel E-PDCCH of a user equipment UE, where
E-PDCCHs at different aggregation levels correspond to different
reference signal ports, and the aggregation level indicates the
quantity of control channel elements included in the E-PDCCH; and a
sending unit, configured to send the E-PDCCH to the UE in a
subframe, and send a reference signal of the E-PDCCH to the UE by
using the determined reference signal port.
[0022] According to another aspect, a user equipment is provided,
including: a sending unit, configured to receive a reference signal
of a candidate E-PDCCH from a reference signal port in a subframe,
where candidate E-PDCCHs at different aggregation levels correspond
to different reference signal ports, and the aggregation level
indicates the quantity of control channel elements included in the
candidate E-PDCCH; and a demodulating unit, configured to perform
channel estimation according to the reference signal, so as to
demodulate the candidate E-PDCCH.
[0023] According to another aspect, a base station is provided,
including: a sending unit, configured to send a reference signal of
the E-PDCCH by using a first reference signal port v, and send a
reference signal of the PDSCH by using at least one second
reference signal port; and a determining unit, configured to
determine not to use a second reference signal port p(v) to send
the reference signal of the PDSCH, so that a reference signal port
of the E-PDCCH and a reference signal port of the PDSCH are
processed based on orthogonal time extensions with different
lengths, where the first reference signal port is one of the at
least one second reference signal port, and v and p(v) are serial
numbers of the reference signal ports.
[0024] According to another aspect, a user equipment is provided,
including: a receiving unit, configured to receive a reference
signal of a physical downlink control channel E-PDCCH which is sent
by a base station by using a first reference signal port v and a
reference signal of a physical downlink shared channel PDSCH which
is sent by the base station by using at least one second reference
signal port, where the PDSCH is invoked by the E-PDCCH; a
demodulating unit, configured to perform channel estimation by
using the reference signal of the E-PDCCH, so as to demodulate the
E-PDCCH, and perform channel estimation by using the reference
signal of the PDSCH, so as to demodulate the PDSCH; and a
determining unit, configured to determine not to use a reference
signal of the PDSCH sent by a second reference signal port p(v) to
perform channel estimation, so that a reference signal port of the
E-PDCCH and a reference signal port of the PDSCH are processed
based on orthogonal time extensions with different lengths, where
the first reference signal port is one of the at least one second
reference signal port, and v and p(v) are serial numbers of the
reference signal ports.
[0025] In the technical solutions, the E-PDCCH can be mapped,
according to an order of OFDM symbols used by an E-PDCCH of a UE,
sequentially to resource elements used to transmit the E-PDCCH in
each OFDM symbol, so that different control channel elements will
not include a same E-PDCCH modulation symbol, thereby avoiding that
the UE incorrectly judges a start position of the E-PDCCH.
BRIEF DESCRIPTION OF DRAWINGS
[0026] To describe the technical solutions in the embodiments of
the present invention more clearly, the following briefly
introduces the accompanying drawings required for describing the
embodiments or the prior art. Apparently, the accompanying drawings
in the following description show merely some embodiments of the
present invention, and a person of ordinary skill in the art may
still derive other drawings from these accompanying drawings
without creative efforts.
[0027] FIG. 1 is a schematic diagram of an eCCE division according
to an embodiment of the present invention;
[0028] FIG. 2 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 1 of the
present invention;
[0029] FIG. 3 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 2 of the
present invention;
[0030] FIG. 4 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 3 of the
present invention;
[0031] FIG. 5 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 4 of the
present invention;
[0032] FIG. 6 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 5 of the
present invention;
[0033] FIG. 7 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 6 of the
present invention;
[0034] FIG. 8A is a schematic flowchart of a process for
transmitting downlink control information according to Embodiment 7
of the present invention;
[0035] FIG. 8B is a schematic diagram showing physical resource
mapping on a PDCCH according to an embodiment of the present
invention;
[0036] FIG. 9A is a schematic flowchart of a process for
transmitting downlink control information according to Embodiment 8
of the present invention;
[0037] FIG. 9B and FIG. 9C are examples of allocating a DMRS port
to a candidate E-PDCCH;
[0038] FIG. 10 is a schematic flowchart of a process for
transmitting downlink control information according to Embodiment 9
of the present invention;
[0039] FIG. 11 is a schematic structural diagram of a base station
according to Embodiment 10 of the present invention;
[0040] FIG. 12 is a schematic structural diagram of a user
equipment according to Embodiment 11 of the present invention;
[0041] FIG. 13 is a schematic structural diagram of a base station
according to Embodiment 12 of the present invention;
[0042] FIG. 14 is a schematic structural diagram of a user
equipment according to Embodiment 13 of the present invention;
[0043] FIG. 15 is a schematic structural diagram of a base station
according to Embodiment 14 of the present invention;
[0044] FIG. 16 is a schematic structural diagram of a user
equipment according to Embodiment 15 of the present invention;
[0045] FIG. 17 is a schematic diagram of physical resources
according to Embodiment 16 of the present invention;
[0046] FIG. 18 is a first schematic diagram of an aggregation level
and reference signal port correspondence according to Embodiment 16
of the present invention;
[0047] FIG. 19 is a second schematic diagram of an aggregation
level and reference signal port correspondence according to
Embodiment 16 of the present invention;
[0048] FIG. 20 is a third schematic diagram of an aggregation level
and reference signal port correspondence according to Embodiment 16
of the present invention; and
[0049] FIG. 21 is a schematic diagram describing a start position
according to Embodiment 16 of the present invention.
DESCRIPTION OF EMBODIMENTS
[0050] The following clearly and completely describes the technical
solutions in the embodiments of the present invention with
reference to the accompanying drawings in the embodiments of the
present invention. Apparently, the described embodiments are a part
rather than all of the embodiments of the present invention. All
other embodiments obtained by a person of ordinary skill in the art
based on the embodiments of the present invention without creative
efforts shall fall within the protection scope of the present
invention.
[0051] It should be understood that technical solutions of the
present invention may be applied to various communications systems,
for example, a GSM (Global System of Mobile communication) system,
a CDMA (Code Division Multiple Access) system, a WCDMA (Wideband
Code Division Multiple Access) system, a GPRS (General Packet Radio
Service) system, an LTE (Long Term Evolution) system, an LTE-A
(Advanced long term evolution) system, a UMTS (Universal Mobile
Telecommunication System), and the like, which are not limited in
the embodiments of the present invention, but for convenience of
description, the embodiments of the present invention will be
described by using an LTE system network as an example.
[0052] The embodiments of the present invention may be applied to
wireless networks under different standards. A radio access network
may include different network elements in different systems. For
example, network elements of a radio access network in LTE and
LTE-A include an eNB (Evolved Node B, evolved base station), while
network elements of a radio access network in WCDMA includes an RNC
(Radio Network Controller) and a base station Node B. Similarly, a
WiMax (Worldwide Interoperability for Microwave Access) and other
wireless networks may also use solutions similar to those in the
embodiments of the present invention, but a relevant module in a
base station system may be different, which is not limited in the
embodiments of the present invention, but for convenience of
description, the following embodiments will be described by using
an eNodeB as an example.
[0053] It should be further understood that, in the embodiments of
the present invention, a user equipment (UE) includes but is not
limited to a mobile station (MS), a mobile terminal, a mobile
telephone, a handset, portable equipment, or the like. The user
equipment may communicate with one or more core networks through a
radio access network (RAN; for example, the user equipment may be a
mobile phone (or called a "cellular" phone), a computer with a
radio communication function, or the like; and the user equipment
may also be a portable, pocket-sized, handheld, computer-embedded,
or vehicle-mounted mobile device.
[0054] FIG. 1 is a schematic diagram of an eCCE division according
to an embodiment of the present invention. Referring to FIG. 1,
after REs occupied by Cell-specific reference signals (CRS), REs
occupied by a later compatible control channel (for example, a
legacy PDCCH) and REs occupied by a reference signal of an E-PDCCH
are excluded, each PRB pair may be divided into 4 eCCEs. FIG. 1
shows a possible division method. The embodiment according to the
present invention is not limited to this eCCE division method, and
does not limit that all eCCEs should have the same number of REs.
An E-PDCCH and a PDSCH are multiplexed in an FDM mode in a data
area of a subframe. Transmission of an E-PDCCH is formed by two
parts, that is, a reference signal part and a data symbol part.
[0055] According to an E-PDCCH mapping mode, E-PDCCHs may be
classified into localized E-PDCCHs and distributed E-PDCCHs. A
localized E-PDCCH is mapped in one PRB pair or adjacent PRB pairs
in a centralized way, so that a base station can select, according
to a channel state report of a UE, a PRB pair in a better channel
condition to send the E-PDCCH, so as to obtain a frequency
scheduling gain. A distributed E-PDCCH is dispersed and mapped to
multiple PRB pairs, so as to obtain a frequency diversity benefit.
The embodiment according to the present invention is described by
using a localized E-PDCCH as an example.
[0056] The foregoing problem that a UE judges a start position of
an E-PDCCH incorrectly may be solved by adding a filling bit, for
example, by finding, according to sizes of different E-PDCCH
formats and numbers of CCEs of different CCE aggregations, sizes of
all E-PDCCHs that are possible to cause unclearness of a feedback
information resource, and making a list. If a base station detects
that the quantity of original bits of an E-PDCCH that needs to be
sent meets any one in the above list, the base station will add a
zero behind the original bits of the E-PDCCH. The E-PDCCH corrected
by adding a zero prevents the mentioned problem that different
eCCEs transmit same encoded E-PDCCH information. However, this
method increases feedback overhead.
[0057] In addition, although the method of adding a filling bit
solves the problem that a UE judges a start position of an E-PDCCH
incorrectly, a problem cannot be avoided that the UE identifies an
aggregation level of the E-PDCCH incorrectly. An E-PDCCH formed by
4 eCCEs is still used as an example. As a filling bit is added, it
is impossible for the UE to detect an E-PDCCH at aggregation level
2 on the third eCCE and the fourth eCCE, but still possible that
the UE detect an E-PDCCH at aggregation level 2 on the first eCCE
and the second eCCE. As the E-PDCCH is sent in a data area of a
subframe, and is multiplexed with a PDSCH based on FDM, if the
aggregation level detection is incorrect, transmission of the PDSCH
will possibly be affected. For example, it is assumed that one RBG
has 3 PRB pairs, and one PRB pair has two eCCEs; that the base
station sends an E-PDCCH at aggregation level 4 to a UE, which
occupies 4 eCCEs of PRB pairs numbered 0 and 1 in RBG0; and that
resources allocated to the PDSCH are RBG0 and RBG1, where resources
in RBG0 other than those for the E-PDCCH, can be used to transmit
the PDSCH, which is to say, PDSCH resources that the base station
allocates are PRB pairs numbered 2, 3, 4 and 5. During E-PDCCH
blind detection at a UE end, if the UE detects an E-PDCCH at
aggregation level 2 on a PRB pair numbered 0, the UE regards that
the PDSCH occupies PRB pairs numbered 1, 2, 3, 4 and 5, thereby
causing an incorrect PDSCH reception. In addition, a similar
problem will also occur when an E-PDCCH and a PDSCH are multiplexed
in a same PRB pair.
Embodiment 1
[0058] FIG. 2 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 1 of the
present invention. The method in FIG. 2 may be executed by a base
station.
[0059] 210: A base station maps, according to an order of OFDM
symbols used by an E-PDCCH of a UE, the E-PDCCH sequentially to REs
used to transmit the E-PDCCH in each OFDM symbol.
[0060] For example, each E-PDCCH may include L (L=1, 2, 4 or 8)
eCCEs; that is to say, REs used by the E-PDCCH may be divided into
L eCCEs. Assuming that OFDM symbols used by the E-PDCCH of the UE
are symbols from the n.sup.th symbol to the m.sup.th symbol, when
physical resource mapping is performed, according to an ascending
order of indexes the OFDM symbols, a first part of modulation
symbols of the E-PDCCH may be firstly mapped to REs used to
transmit the E-PDCCH in the n.sup.th symbol, and then a second part
of symbols may be mapped to REs used to transmit the E-PDCCH in the
(n+1).sup.th symbol, and so on, till a last part of modulation
symbols are finally mapped to REs used to transmit the E-PDCCH in
the m.sup.th symbol. Certainly, the embodiment of the present
invention is not limited thereto; for example, another order (for
example, a descending order of indexes of the OFDM symbols or other
specific orders) may also be used to perform physical resource
mapping.
[0061] 220: The base station sends the E-PDCCH to the UE by using
the REs, where the E-PDCCH and a PDSCH invoked by the E-PDCCH are
frequency-division multiplexed.
[0062] For example, that the E-PDCCH and a PDSCH invoked by the
E-PDCCH are frequency-division multiplexed means that an E-PDCCH
and a PDSCH in LTE11 are frequency-division multiplexed on REs of
data part.
[0063] In the embodiment of the present invention, the E-PDCCH can
be mapped, according to the order of OFDM symbols used by the
E-PDCCH of the UE, sequentially to the REs used to transmit the
E-PDCCH in each OFDM symbol, so that, for candidate E-PDCCHs at a
same start eCCE but different aggregation levels, different eCCEs
will not include E-PDCCH modulation symbols of a same index,
thereby avoiding that the UE judges a start position of the E-PDCCH
incorrectly. In addition, a problem that E-PDCCHs at a same start
position but different aggregation levels are mixed up is also
solved.
[0064] In 210, when the E-PDCCH is mapped sequentially to the REs
used to transmit the E-PDCCH in each OFDM symbol, in each OFDM
symbol, the E-PDCCH may be sequentially mapped, according to an
order of L eCCEs allocated to the E-PDCCH, to REs occupied by the L
eCCEs in the OFDM symbol, where L is an integer.
[0065] For example, before physical resource mapping is performed,
REs that can be used to transmit the E-PDCCH in a PRB pair may be
firstly divided into multiple eCCEs. Another division method is to
disperse REs of each eCCE to all OFDM symbols of a data part with
limitation to a part of subcarriers of the PRB pair, or disperse
the REs of each eCCE to all OFDM symbols of the data part and
subcarriers of the PRB pair. Under this situation, if the E-PDCCH
is sequentially mapped, according to the order of L eCCEs allocated
to the E-PDCCH, to REs occupied by the L eCCEs in the OFDM symbol,
it can be ensured that, for candidate E-PDCCHs at a same start eCCE
but different aggregation levels, different eCCEs will not have
E-PDCCH modulation symbols of a same index.
[0066] In 210, when the E-PDCCH is mapped sequentially to the REs
used to transmit the E-PDCCH in each OFDM symbol, in each OFDM
symbol, modulation symbols of the e-PDCCH with index numbers of
j 0 + q = 0 l - 1 N q + [ 0 , , N l - 1 ] ##EQU00001##
may be mapped, according to the order of the L eCCEs allocated to
the E-PDCCH, sequentially to REs of a set R.sub.l, where the set
R.sub.l is a set of REs occupied by the l.sup.th eCCE among the L
eCCEs included in the E-PDCCH, j.sub.0 is a start position of the
modulation symbols of the e-PDCCH mapped in the OFDM symbol,
N.sub.l is the quantity of the REs in the set R.sub.l, and N.sub.l,
j.sub.0, l and q are integers.
[0067] For example, an E-PDCCH at aggregation level L may include L
eCCEs, and have a modulation symbol sequence S.sub.j, where j=0, .
. . J-1, where J is the total number of REs of the L eCCEs included
in the E-PDCCH, and j is an index number of an E-PDCCH modulation
symbol. According to the embodiment of the present invention, an
E-PDCCH sequence S.sub.j may be mapped sequentially to the REs used
to transmit the E-PDCCH in each OFDM symbol.
[0068] In 210, when the E-PDCCH is mapped sequentially to the REs
used to transmit the E-PDCCH in each OFDM symbol, in each OFDM
symbol, the base station maps, according to an order of
subcarriers, the E-PDCCH sequentially to REs occupied by L eCCEs
allocated to the E-PDCCH.
[0069] In 210, when the E-PDCCH is mapped sequentially to the REs
used to transmit the E-PDCCH in each OFDM symbol, in each OFDM
symbol, modulation symbols of the e-PDCCH with index numbers of
j.sub.0+[0, . . . , N-1] may be mapped sequentially to REs of a set
R, where j.sub.0 is a start position of modulation symbols of the
E-PDCCH mapped in the OFDM symbol, the set R is a set of REs
occupied by L eCCEs included in the E-PDCCH in the OFDM symbol, N
is the quantity of the REs in set R, and N and j.sub.0 are
integers.
Embodiment 2
[0070] FIG. 3 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 2 of the
present invention. The method in FIG. 3 is executed by a UE. The
method in FIG. 3 corresponds to the method in FIG. 2, and detailed
descriptions here are omitted appropriately.
[0071] 310: The UE receives a downlink subframe from a base
station.
[0072] 320: The UE extracts, in a blind detection process according
to an order of OFDM symbols used by a candidate E-PDCCH in the
downlink subframe, modulation symbols of the candidate E-PDCCH
sequentially from REs used to transmit the candidate E-PDCCH in
each OFDM symbol, and performs decoding and CRC check on the
candidate E-PDCCH, where the E-PDCCH of the UE and a PDSCH invoked
by the E-PDCCH of the UE are frequency-division multiplexed.
[0073] In the embodiment of the present invention, modulation
symbols of the candidate E-PDCCH can be obtained, according to an
order of OFDM symbols used by a candidate E-PDCCH of the UE,
sequentially from REs used to transmit the E-PDCCH in each OFDM
symbol, so that, for candidate E-PDCCHs at a same start eCCE but
different aggregation levels, different eCCEs will not include a
same E-PDCCH modulation symbol, thereby avoiding a problem that the
UE judges a start position of the E-PDCCH incorrectly, and solves a
problem that E-PDCCHs at a same start position but different
aggregation levels are mixed up.
[0074] In 320, when the UE uses, in the blind detection process,
the order of OFDM symbols used by the candidate E-PDCCH, in each
OFDM symbol, the UE may extract, according to an order of L eCCEs
allocated to the candidate E-PDCCH, the modulation symbols of the
candidate E-PDCCH sequentially from REs occupied by the L eCCEs in
the OFDM symbol, where L is an integer.
[0075] In 320, when the UE uses, in the blind detection process,
the order of OFDM symbols used by the candidate E-PDCCH, in each
OFDM symbol, the UE may extract modulation symbols of the candidate
E-PDCCH and with index numbers of
j 0 + q = 0 l - 1 N q + [ 0 , , N l - 1 ] ##EQU00002##
from REs of a set R.sub.l, where the set R.sub.l is a set of REs
occupied by the l.sup.h eCCE among the L eCCEs included in the
candidate E-PDCCH in the OFDM symbol, j.sub.0 is a start position
of the modulation symbols of the candidate E-PDCCH mapped in the
OFDM symbol, N.sub.l is the quantity of the REs in the set R.sub.l,
and N.sub.l, j.sub.0, l and q are integers.
[0076] In 320, when the UE uses, in the blind detection process,
the order of OFDM symbols used by the candidate E-PDCCH, in each
OFDM symbol, the UE may extract, according to an order of
subcarriers, modulation symbols of the candidate E-PDCCH from REs
occupied by the L eCCEs allocated to the candidate E-PDCCH.
[0077] In 320, when the UE uses, in the blind detection process,
the order of OFDM symbols used by the candidate E-PDCCH, in each
OFDM symbol, the UE may extract modulation symbols of the candidate
E-PDCCH and with index numbers of j.sub.0+[0, . . . , N-1] from REs
of a set R, where j.sub.0 is a start position of the modulation
symbols of the candidate E-PDCCH mapped in the OFDM symbol, the set
R is a set of REs occupied by L eCCEs and included in the candidate
E-PDCCH in the OFDM symbol, N is the quantity of the REs in the set
R, and N and j.sub.0 are integers.
Embodiment 3
[0078] FIG. 4 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 3 of the
present invention. The method in FIG. 4 is executed by a base
station.
[0079] 410: The base station determines a reference signal port
according to an aggregation level of an E-PDCCH of a UE, where
E-PDCCHs at different aggregation levels correspond to different
reference signal ports, and the aggregation level indicates the
quantity of eCCEs included in the E-PDCCH.
[0080] 420: The base station sends the E-PDCCH to the UE in a
subframe, and sends a reference signal of the E-PDCCH to the UE by
using the determined reference signal port, where the E-PDCCH and a
PDSCH invoked by the E-PDCCH are frequency-division
multiplexed.
[0081] For example, the reference signal may be a DMRS, and the
reference signal port may be a DMRS port. Correspondence between
E-PDCCHs at different eCCE aggregation levels and DMRS ports that
the E-PDCCHs use may be notified by using signaling, or may be
determined by using an implicit method, which means that a
signaling notification is not needed, but some parameters, such as
a cell identity, a UE identity and an aggregation level and the
like are used to determine the correspondence. Different PRB pairs
may have same correspondence, or different correspondence may be
defined for each PRB pair. The correspondence may be cell-specific;
for example, the base station may notify all UEs in a cell by using
broadcast signaling, which means that all the UEs in the cell run
according to same correspondence. The correspondence may also be
UE-specific; for example, the base station may notify a specific UE
by using RRC signaling, which means that different UEs may have
different correspondence.
[0082] For example, in LTE11, corresponding to candidate E-PDCCHs
at aggregation levels 1, 2, 4 and 8, the reference signal is sent
by sequentially using DMRS ports 7, 8, 9 and 10.
[0083] According to the embodiment of the present invention,
reference signals of E-PDCCHs at different eCCE aggregation levels
can be sent by using different DMRS ports, so that the UE can
demodulate an E-PDCCH at each aggregation level correctly according
to a special DMRS reference signal of the E-PDCCH, thereby avoiding
a problem that the UE judges a start position of the E-PDCCH
incorrectly, and solving a problem that E-PDCCHs at a same start
position but different aggregation levels are mixed up.
[0084] According to the embodiment of the present invention, an
E-PDCCH at aggregation level L=2.sup.m-1 corresponds to a reference
signal port with a port number 7+(m+.sigma.)mod P, where m=1, 2, 3,
4, .sigma. is 0 or a UE-specific parameter or a cell-specific
parameter, and P is the quantity of available reference signal
ports for the E-PDCCH, and P=4.
[0085] Optionally, that E-PDCCHs at different aggregation levels
correspond to different reference signal ports may include that,
E-PDCCHs at different aggregation levels, among a part or all of
aggregation levels corresponding to E-PDCCHs of the UE, correspond
to different reference signal ports.
[0086] Optionally, the determining, by the base station, a
reference signal port according to the aggregation level of the
physical downlink control channel E-PDCCH of the UE, where E-PDCCHs
at different aggregation levels correspond to different reference
signal ports may specifically be: selecting, by the base station
according to the aggregation level of the physical downlink control
channel E-PDCCH of the UE, one or more reference signal ports from
a reference signal port set corresponding to the aggregation level
as a reference signal port corresponding to the aggregation level,
where reference signal ports selected for E-PDCCHs at different
aggregation levels are different.
[0087] According to the embodiment of the present invention, in
410, it is acceptable that only E-PDCCHs at a same start position
in the subframe but different aggregation levels correspond to
different reference signal ports. In other words, without depending
on the aggregation level, E-PDCCHs with different start positions
may correspond to a same reference signal port.
[0088] Optionally, as another embodiment, the method in FIG. 4
further includes: configuring, by the base station, correspondence
between eCCEs in the subframe and the reference signal ports, so
that, according to the correspondence between eCCEs in the subframe
and the reference signal ports, enabling E-PDCCHs at a same start
position but different aggregation levels in the subframe
correspond to different reference signal ports.
[0089] Further, the at a same start position in the subframe may
include: at a same start position in a same physical resource block
pair or different physical resource block pairs.
[0090] Further, E-PDCCHs, corresponding to different user
equipments UEs, at a same aggregation level, and occupying a same
physical resource, correspond to different reference signal
ports.
[0091] The correspondence between eCCEs in the subframe and the
reference signal ports includes: the i.sup.th eCCE in the subframe
corresponds to a reference signal port 7+(i+.sigma.)mod P, where i
is an index of the eCCE in the subframe, .sigma. is 0 or a
UE-specific parameter or a cell-specific parameter, and P is the
quantity of available reference signal ports, and P=4, and i is an
integer; in 410, the base station sends a reference signal of the
E-PDCCH at aggregation level L=2.sup.m-1 by using a reference
signal port corresponding to the m.sup.th eCCE in the E-PDCCH at
aggregation level L=2.sup.m-1, where m=1, 2, 3, 4.
Embodiment 4
[0092] FIG. 5 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 4 of the
present invention. The method in FIG. 5 is executed by a UE. The
method in FIG. 5 corresponds to the method in FIG. 4, and detailed
descriptions here are omitted appropriately.
[0093] 510: The UE receives a reference signal of a candidate
E-PDCCH from a reference signal port in a subframe, where candidate
E-PDCCHs at different aggregation levels correspond to different
reference signal ports, and the aggregation level indicates the
quantity of eCCEs included in the candidate E-PDCCH.
[0094] The UE receives, from a reference signal port in a subframe,
a reference signal of a candidate physical downlink control channel
E-PDCCH sent by a base station, where candidate E-PDCCHs at
different aggregation levels correspond to different reference
signal ports, and the aggregation level indicates the quantity of
control channel elements included in the candidate E-PDCCH.
[0095] 520: The UE performs channel estimation according to the
reference signal, so as to demodulate the candidate E-PDCCH.
[0096] Further, optionally, the E-PDCCH of the UE and a PDSCH
invoked by the E-PDCCH of the UE are frequency-division
multiplexed.
[0097] The UE performs channel estimation according to the
reference signal, so as to demodulate the candidate E-PDCCH, where
the candidate E-PDCCH and a physical downlink shared channel PDSCH
invoked by the candidate E-PDCCH are frequency-division
multiplexed.
[0098] For example, assuming that the base station sends an E-PDCCH
at aggregation level 2 and sends a reference signal by using DMRS
port 8, when blindly detecting each candidate E-PDCCH at
aggregation level 1, the UE tries to perform channel estimation
based on DMRS port 7 and demodulate the E-PDCCH; however, in fact,
the base station does not send the reference signal to the UE by
using DMRS port 7; it is quite clear that the demodulated output is
some random noise, so that CRC check is not possible to be
successful, thereby avoiding that the UE mixes up candidate
E-PDCCHs at different aggregation levels.
[0099] According to the embodiment of the present invention,
reference signals of E-PDCCHs at different eCCE aggregation levels
can be sent by using different DMRS ports, thereby avoiding a
problem that the UE judges a start position of the E-PDCCH
incorrectly, and solving a problem that E-PDCCHs at a same start
position but different aggregation levels are mixed up.
[0100] According to the embodiment of the present invention, an
E-PDCCH at aggregation level L=2.sup.m-1 corresponds to a reference
signal port with a port number 7+(m+.sigma.)mod P, where m=1, 2, 3,
4, .sigma. is 0 or a UE-specific parameter or a cell-specific
parameter, and P is the quantity of available reference signal
ports for the E-PDCCH, and P=4.
[0101] Optionally, as another embodiment, in 510, it is acceptable
that only E-PDCCHs at a same start position but different
aggregation levels correspond to different reference signal ports.
In other words, without depending on the aggregation level,
E-PDCCHs with different start positions may correspond to a same
reference signal port.
[0102] The method in FIG. 5 further includes: configuring, by the
UE, correspondence between eCCEs in the subframe and the reference
signal ports, so that, according to the correspondence between
eCCEs in the subframe and the reference signal ports, enabling
E-PDCCHs at a same start position but different aggregation levels
in the subframe correspond to different reference signal ports.
[0103] The correspondence between the eCCEs in the subframe and the
different reference signal ports includes: the i.sup.th eCCE in the
subframe corresponds to a reference signal port 7+(i+.sigma.) mod
P, where i is an index of the eCCE in the subframe, .sigma. is 0 or
a UE-specific parameter or a cell-specific parameter, and P is the
quantity of available reference signal ports, and P=4, and i is an
integer; in 510, the UE may receive a reference signal of an
E-PDCCH at aggregation level L=2.sup.m-1 from a reference signal
port corresponding to the m.sup.th eCCE in the E-PDCCH at
aggregation level L=2.sup.m-1, where m=1, 2, 3, 4.
[0104] Optionally, that candidate E-PDCCHs at different aggregation
levels correspond to different reference signal ports may
specifically be: selecting, by the UE, according to the aggregation
level of the candidate E-PDCCH of the UE, one or more reference
signal ports from a reference signal port set corresponding to the
aggregation level as a reference signal port corresponding to the
aggregation level, where candidate E-PDCCHs at different
aggregation levels correspond to different reference signal
ports.
[0105] Further, that candidate E-PDCCHs at different aggregation
levels correspond to different reference signal ports may include:
that candidate E-PDCCHs at a same start position but different
aggregation levels in the subframe correspond to different
reference signal ports.
[0106] Optionally, that candidate E-PDCCHs at different aggregation
levels correspond to different reference signal ports may
include:
[0107] that candidate E-PDCCHs at different aggregation levels,
among a part or all of aggregation levels corresponding to
candidate E-PDCCHs of the UE, correspond to different reference
signal ports.
Embodiment 5
[0108] FIG. 6 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 5 of the
present invention. The method in FIG. 6 is executed by a base
station.
[0109] 610: The base station sends a reference signal of the
E-PDCCH by using a first reference signal port v.
[0110] 620: The base station sends a reference signal of the PDSCH
by using at least one second reference signal port.
[0111] 630: The base station determines not to use a second
reference signal port p(v) to send the reference signal of the
PDSCH, so that a reference signal port of the E-PDCCH and a
reference signal port of the PDSCH are processed based on
orthogonal time extensions with different lengths, where the
E-PDCCH and the PDSCH are frequency-division multiplexed, the first
reference signal port may be one of the at least one second
reference signal port, and v and p(v) are serial numbers of the
reference signal ports.
[0112] For example, LTE release 11 supports multiplexing of an
E-PDCCH and a PDSCH; in order that a DMRS port with respect to an
E-PDCCH is processed based on an orthogonal time extension with a
length of 2, and also that. when a PDSCH with a rank of 5, 6 or 7
is scheduled by the E-PDCCH, a DMRS port with respect to a PDSCH is
processed based on an orthogonal time extension with a length of 4,
the present invention proposes the following limitation on the DMRS
ports for the PDSCH; that is to say, when a DMRS port occupied by
the E-PDCCH of the UE is v, a DMRS port p(v) is defined not to be
used to demodulate the PDSCH, or, another DMRS port is needed to
replace the p(v), so that a reference signal port of the E-PDCCH
and a reference signal port of the PDSCH are processed based on
orthogonal time extensions with different lengths, and that the
E-PDCCH and the PDSCH can be multiplexed normally.
[0113] According to the embodiment of the present invention, when
sending the reference signal of the PDSCH by using a reference
signal port results that the reference signal ports of the E-PDCCH
and the PDSCH cannot be processed based on orthogonal time
extensions with different lengths, the reference signal port may be
not used to send the reference signal of the PDSCH, so that the
reference signal of the PDSCH and the reference signal of the
E-PDCCH are multiplexed normally.
[0114] According to the embodiment of the present invention, the at
least one second reference signal port includes at least one of
PDSCH reference signal ports 7, 8, 9, 10, 11, 12, 13 and 14 defined
in LTE release 10, the first reference signal port includes an
E-PDCCH reference signal port 7, 8, 9, or 10 defined in LTE release
10, and
p ( v ) = { 11 , v = 7 13 , v = 8 12 , v = 9 14 , v = 10 .
##EQU00003##
[0115] In 620, when a rank R of the PDSCH is less than or equal to
4, the base station may send the reference signal of the PDSCH by
using a PDSCH reference signal port defined in LTE release 10.
[0116] Optionally, as another embodiment, when the rank of the
PDSCH is one of 5, 6 and 7, the base station sends the reference
signal of the PDSCH by using a PDSCH reference signal port defined
in LTE release 10, and when needing to send the reference signal of
the PDSCH by using the second reference signal port p(v), replaces
the reference signal port p(v) with another available reference
signal port among the PDSCH reference signal ports, where R is an
integer.
[0117] According to the embodiment of the present invention, when a
rank R of the PDSCH is less than or equal to 4, the base station
sends the reference signal of the PDSCH by using R reference signal
ports 7+(v-7+r)mod 4 starting from the reference signal port v,
where r=0, . . . , R-1, and R is an integer.
[0118] Optionally, as another embodiment, when the rank R of the
PDSCH is equal to one of 5, 6 and 7, the base station sends the
reference signal of the PDSCH by using R reference signal ports
7+(v-7+r) mod 8 starting from the reference signal port v, and when
the R reference signal ports include the reference signal port
p(v), replaces the reference signal port p(v) with another
reference signal port among the PDSCH reference signal ports, where
r=0, . . . , R-1.
[0119] Optionally, as another embodiment, when a rank R of the
PDSCH is equal to 3 or 4, the base station may send the reference
signal of the PDSCH by using R reference signal ports 7+(v-7+r) mod
4 starting from the reference signal port v, where R is an integer,
r=0, . . . , R-1; and when the rank R of the PDSCH is equal to 2,
the base station sends the send the reference signal of the PDSCH
by using reference signal ports v and v+(-1).sup.(v-7)mod 2.
Embodiment 6
[0120] FIG. 7 is a schematic flowchart of a method for transmitting
downlink control information according to Embodiment 6 of the
present invention. The method in FIG. 7 is executed by a UE. The
method in FIG. 7 corresponds to the method in FIG. 6, and detailed
descriptions here are omitted appropriately.
[0121] 710: The UE receives a reference signal of an E-PDCCH which
is sent by a base station by using a first reference signal port v
and a reference signal of a PDSCH which is sent by the base station
by using at least one second reference signal port, where the PDSCH
is invoked by the E-PDCCH.
[0122] 720: The UE performs channel estimation by using the
reference signal of the E-PDCCH, so as to demodulate the E-PDCCH,
and performs channel estimation by using the reference signal of
the PDSCH, so as to demodulate the PDSCH.
[0123] 730: The base station determines not to use the reference
signal of the PDSCH sent by a second reference signal port p(v) to
perform channel estimation, so that a reference signal port of the
E-PDCCH and a reference signal port of the PDSCH are processed
based on orthogonal time extensions with different lengths, where
the E-PDCCH and the PDSCH are frequency-division multiplexed, the
first reference signal port may be one of the at least one second
reference signal port, and v and p(v) are serial numbers of the
reference signal ports.
[0124] According to the embodiment of the present invention, when
sending the reference signal of the PDSCH by using a reference
signal port results that the reference signal ports of the E-PDCCH
and the PDSCH cannot be processed according to orthogonal time
extensions with different lengths, the reference signal port may be
not used to send the reference signal of the PDSCH, so that the
reference signal of the PDSCH and the reference signal of the
E-PDCCH are multiplexed normally.
[0125] According to the embodiment of the present invention, the at
least one second reference signal port includes at least one of
PDSCH reference signal ports 7, 8, 9, 10, 11, 12, 13 and 14 defined
in LTE release 10; that is to say, the second reference signal port
includes the PDSCH reference signal ports 7, 8, 9, 10, 11, 12, 13
or 14 defined in LTE release 10, the first reference signal port
includes an E-PDCCH reference signal port 7, 8, 9, or 10 defined in
LTE release 10, and
p ( v ) = { 11 , v = 7 13 , v = 8 12 , v = 9 14 , v = 10 .
##EQU00004##
[0126] According to the embodiment of the present invention, when a
rank R of the PDSCH is less than or equal to 4, the UE performs
channel estimation by using a reference signal of the PDSCH sent by
a PDSCH reference signal port defined in LTE release 10.
[0127] According to the embodiment of the present invention, when
the rank R of the PDSCH is one of 5, 6 and 7, the UE may perform
channel estimation by using a reference signal of the PDSCH sent by
a PDSCH reference signal port defined in LTE release 10, and when
needing to perform channel estimation by using the reference signal
of the PDSCH sent by the second reference signal port p(v),
replaces the reference signal port p(v) with another available
reference signal port among the PDSCH reference signal ports to
perform channel estimation.
[0128] Optionally, as another embodiment, when a rank R of the
PDSCH is less than or equal to 4, the UE performs channel
estimation by using reference signals of the PDSCH sent by R
reference signal ports 7+(v-7+r) mod 4 starting from the reference
signal port v, where r=0, . . . , R-1, and R is an integer; or,
when the rank R of the PDSCH is equal to one of 5, 6 and 7, the UE
performs channel estimation by using reference signals of the PDSCH
sent by R reference signal ports 7+(v-7+r) mod 8 starting from the
reference signal port v, and when the R reference signal ports
include the reference signal port p(v), replaces the reference
signal port p(v) with another reference signal port among the PDSCH
reference signal ports to perform channel estimation, where r=0, .
. . , R-1.
[0129] According to the embodiment of the present invention, when a
rank R of the PDSCH is equal to 3 or 4, the UE performs channel
estimation by using reference signals of the PDSCH sent by R
reference signal ports 7+(v-7+r) mod 4 starting from the reference
signal port v, where r=0, . . . , R-1; and when the rank of the
PDSCH is equal to 2, the UE performs channel estimation by using
reference signals of the PDSCH sent by reference signal ports v and
v+(-1).sup.(v-7)mod 2.
[0130] With reference to a specific example, the following
describes the embodiments of the present invention in more
detail.
Embodiment 7
[0131] FIG. 8A is a schematic flowchart of a process for
transmitting downlink control information according to Embodiment 7
of the present invention. FIG. 8B is a schematic diagram showing
physical resource mapping on a PDCCH according to an embodiment of
the present invention. Embodiment 7 elaborates one or more steps of
the methods in Embodiment 1 and Embodiment 2.
[0132] 810: A base station performs CRC check code addition,
scrambling, encoding and rate matching on downlink control
information of a UE, so as to obtain modulation symbols of a
PDCCH.
[0133] For example, scrambling may be performed on the downlink
control information of the UE by using 16-bit cyclic redundancy
check (CRC) and a radio network temporary identity (RNTI), and
encoding and rate matching is performed on the downlink control
information of the UE by using convolutional encoding with master
code being 1/3 and a circular buffering based rate, so as to obtain
modulation symbols of a PDCCH.
[0134] 820: The base station maps, according to an order of OFDM
symbols used by a PDCCH, the PDCCH sequentially to REs used to
transmit the E-PDCCH in each OFDM symbol.
[0135] Before physical resource mapping is performed, REs that can
be used to transmit the E-PDCCH in a PRB pair may be divided into
several eCCEs. Here, a specific eCCE division method is not
limited.
[0136] Specifically, for a localized E-PDCCH, a simple eCCE
division method is to limit an eCCE to a part of subcarriers, for
example, a division method in FIG. 1. Another method is to disperse
REs of each eCCE to all subcarriers and all OFDM symbols of a data
part of the PRB pair, for example, assuming that the quantity of
REs available for the E-PDCCH in the PRB pair is N, and the REs are
divided into K eCCEs. Particularly, the K eCCEs may have an equal
size, that is, .left brkt-bot.N/K.right brkt-bot.; under this
situation, the quantity of REs that are not used is N mod K. In
order to fully utilize all REs, and ensure that sizes of eCCEs
divided in a PRB pair are as close as possible, a simple method is
to allocate a size of .left brkt-top.N/K.right brkt-bot. to the
first N mod K eCCEs, and allocate a size of .left
brkt-bot.N/K.right brkt-bot. to other eCCEs. However, this method
may cause uneven sizes of candidate E-PDCCHs at aggregation level
2; for example, assuming that K is equal to 4, and N mod K=2, and
assuming that the first two eCCEs form a candidate E-PDCCH at
aggregation level 2, while the last two eCCEs form another
candidate E-PDCCH at aggregation level 2, a difference in the
numbers of REs between the two candidate E-PDCCHs is 2, but in
fact, the two candidate E-PDCCHs may possibly have an equal number
of REs. Therefore, another method to allocate eCCE sizes is to map
eCCEs with a size of .left brkt-top.N/K.right brkt-bot. in the PRB
pair to discontinuous eCCE indexes, for example, to define a size
of an eCCE with an index of .left brkt-bot.kK/(N mod K).right
brkt-bot. as .left brkt-top.N/K.right brkt-bot., where k=0, . . . ,
N mod K-1, and define a size of other eCCEs as .left
brkt-bot.N/K.right brkt-bot..
[0137] Similarly, for a distributed E-PDCCH, assuming that a total
number of available REs in a PRB pair of the distributed E-PDCCH is
N, and the REs are divided into K eCCEs. Particularly, the K eCCEs
may have an equal size, that is, .left brkt-bot.N/K.right
brkt-bot.; under this situation, the quantity of REs that are not
used is N mod K. In order to fully utilize all REs, and ensure that
sizes of eCCEs divided in a PRB pair are as close as possible, a
simple method is to allocate a size of .left brkt-top.N/K.right
brkt-bot. to the first N mod K eCCEs, and allocate a size of .left
brkt-bot.N/K.right brkt-bot. to other eCCEs. Optionally, as another
embodiment, eCCEs with a size of .left brkt-top.N/K.right brkt-bot.
may be mapped to discontinuous eCCE indexes, for example, to define
a size of an eCCE with an index of .left brkt-bot.kK/(N mod
K).right brkt-bot. as .left brkt-top.N/K.right brkt-bot., where
k=0, . . . , N mod K-1, and define a size of another eCCE as .left
brkt-bot.N/K.right brkt-bot..
[0138] According to the embodiment of the present invention, an
E-PDCCH at aggregation level L may include L eCCEs, and have a
modulation symbol sequence S.sub.p where j=0, . . . J-1, where J is
a total number of REs of the L eCCEs included in the E-PDCCH. The
base station performs physical resource mapping on each E-PDCCH.
The base station may, according to a frequency priority method,
firstly map the E-PDCCH to REs occupied by L eCCEs allocated to the
E-PDCCH on an OFDM symbol of the E-PDCCH, and then map the E-PDCCH
to REs occupied by the L eCCEs allocated to the E-PDCCH on a next
OFDM symbol of the E-PDCCH.
[0139] Specifically, in an OFDM symbol, the E-PDCCH may be firstly
mapped to REs occupied by an eCCE among the L eCCEs included in the
E-PDCCH, and then mapped to REs occupied by a next eCCE. Assuming
that in an OFDM symbol, a RE set occupied by the l.sup.th eCCE
among the L eCCEs included in the E-PDCCH is R.sub.l, and the
quantity of REs included in the set is N.sub.l, modulation symbols
of the e-PDCCH with an index j within a range
j 0 + q = 0 l - 1 N q + [ 0 , , N l - 1 ] ##EQU00005##
are mapped sequentially to the REs of the set R.sub.l according to
an order of eCCEs, where j.sub.0 is a start position of the
modulation symbols of the E-PDCCH mapped in the OFDM symbol.
[0140] Optionally, as another embodiment, in an OFDM symbol, for
REs of L eCCEs allocated to the E-PDCCH, eCCEs are not
differentiated and mapping is performed according to an order of
subcarriers. Assuming that, in an OFDM symbol, a RE set occupied by
L eCCEs included in an E-PDCCH is R, and a total number of REs
included in the set is N, modulation symbols of the e-PDCCH with an
index j within a range j.sub.0+[0, . . . , N-1] are mapped
sequentially to the REs of the set R, where j.sub.0 is a start
position of the modulation symbols of the E-PDCCH mapped in the
OFDM symbol.
[0141] Referring to FIG. 8B, FIG. 8B shows physical resource
mapping of an E-PDCCH at aggregation level 1 and physical resource
mapping of an E-PDCCH at aggregation level 2. It can be seen from
FIG. 8B that, a modulation symbol of an E-PDCCH at aggregation
level 2 mapped in eCCE0 is almost completely different with a
modulation symbol of an E-PDCCH at aggregation level 1 mapped in
eCCE0 or eCCE1.
[0142] 830: The base station sends the E-PDCCH to the UE by using a
RE, and sends the PDSCH scheduled by the E-PDCCH to the UE.
[0143] 840: After receiving a downlink subframe from the base
station, the UE extracts, in a blind detection process according to
an order of OFDM symbols used by a candidate E-PDCCH, modulation
symbols of the candidate E-PDCCH sequentially from REs used to
transmit the candidate E-PDCCH in each OFDM symbol.
[0144] For a PDSCH and an E-PDCCH transmitted in a subframe, the UE
firstly needs to blindly detect the E-PDCCH, that is, to detect,
from all candidate E-PDCCHs in a search space of the UE, the
E-PDCCH that the base station sends to the UE. For example, the UE
performs channel estimation based on a reference signal part, and
performs demodulation, decoding and CRC check and like operations
on a data symbol part, so as to obtain downlink control information
(DCI) of the UE transmitted on the E-PDCCH.
[0145] Referring to FIG. 8B again, assuming that the base station
actually sends an E-PDCCH at aggregation level 2 by using eCCE0 and
eCCE1, it is impossible that the UE detect an E-PDCCH at
aggregation level 1 on eCCE0 and eCCE1. Therefore, according to the
method in the embodiment of the present invention, the foregoing
problem that a start position of the E-PDCCH is judged incorrectly
and the problem that E-PDCCHs at a same start position but
different aggregation levels are mixed up are both solved.
[0146] 850: If detecting its own E-PDCCH, the UE demodulates a
corresponding PDSCH according to the downlink control information
in the E-PDCCH, and feeds back in the uplink according to whether
the PDSCH demodulation is correct.
[0147] For example, if the PDSCH is demodulated correctly, the UE
feeds back an acknowledgement (ACK) message to the eNodeB,
indicating that the UE has already correctly received data sent by
the eNodeB, and the eNodeB may transmit new data. Otherwise, the UE
feeds back a negative-acknowledgement (NACK) message to the eNodeB,
indicating that the data has not been received correctly, and the
eNodeB needs to retransmit the data. Another situation is that the
E-PDCCH has not been detected correctly, so that the UE assumes
that no data is scheduled to the UE, and does not feed back
anything in an uplink, which means discontinuous transmission
(DTX).
Embodiment 8
[0148] FIG. 9A is a schematic flowchart of a process for
transmitting downlink control information according to Embodiment 8
of the present invention. Embodiment 8 elaborates one or more steps
of the methods in Embodiment 3 and Embodiment 4.
[0149] According to the embodiment of the present invention, a
localized E-PDCCH is used as an example for description. As a
reference signal of an E-PDCCH is dedicated to one UE, a reference
signal port (that is a DMRS port) and eCCEs occupied by the E-PDCCH
both need to be defined in a design of an E-PDCCH search space.
According to the embodiment of the present invention, reference
signals of E-PDCCHs at different eCCE aggregation levels can be
sent by using different DMRS ports, so as to prevent the UE from
mixing up the E-PDCCHs at different eCCE aggregation levels.
[0150] 910: A base station performs CRC check code addition,
scrambling, encoding and rate matching on downlink control
information of a UE, so as to obtain modulation symbols of a PDCCH.
910 in FIG. 9 is similar to 810 in FIG. 8, and is not described
here any further.
[0151] 920: The base station maps an E-PDCCH to a physical source,
and determines a reference signal port according to an aggregation
level of the E-PDCCH of the UE, where E-PDCCHs at different
aggregation levels correspond to different reference signal
ports.
[0152] Correspondence between E-PDCCHs at different eCCE
aggregation levels and DMRS ports that the E-PDCCHs use may be
notified by using signaling, or may be determined by using an
implicit method, which means that a signaling notification is not
needed, but some parameters, such as a cell identity, a UE identity
and an aggregation level and the like are used to determine the
correspondence. Different PRB pairs may have same correspondence,
or different correspondence may be defined for each PRB pair. The
correspondence may be cell-specific; for example, the base station
may notify all UEs in a cell by using broadcast signaling, which
means that all the UEs in the cell run according to same
correspondence. The correspondence may also be UE-specific; for
example, the base station may notify a specific UE by using RRC
signaling, which means that different UEs may have different
correspondence.
[0153] For example, the quantity of DMRS ports available for an
E-PDCCH is P; in LTE release 11, P may be equal to 4; that is to
say, DMRS ports 7, 8, 9 and 10 may be used as E-PDCCH reference
signal ports. Therefore, for a UE, a DMRS port used by a candidate
E-PDCCH at aggregation level L=2.sup.m may be defined as
7+(m+.sigma.)mod P, where .sigma. is a fixed value, for example,
.sigma. is equal to 0; or .sigma. is a cell-specific parameter; or
.sigma. is a specific parameter for each transmission point in a
cell in coordinated multi-point transmission; or .sigma. is a
UE-specific parameter. For example, for a UE, corresponding to
candidate E-PDCCHs at aggregation levels 1, 2, 4 and 8, the
reference signal is sent sequentially by using DMRS ports 7, 8, 9
and 10.
[0154] Optionally, as another embodiment, assuming that a problem
that a start position of an E-PDCCH is judged incorrectly has
already been solved by using another method, for example, by using
a method of adding a filling bit in LTE release 8, only a problem
needs to be solved that E-PDCCHs at a same start position but
different aggregation levels is mixed. Here, it is only necessary
to allocate different DMRS ports to candidate E-PDCCHs at a same
start eCCE but different aggregation levels to send reference
signals; that is to say, for candidate E-PDCCHs with different
start eCCEs, a same DMRS port may be allocated to send reference
signals. Assuming that correspondence between each eCCE and a DMRS
port is defined by using a method, the correspondence may be
notified by using signaling, but with a high overhead; or the
correspondence may be determined by using an implicit method, which
means that no signaling notification is needed, but some parameters
(such as a cell identity, a UE identity and an aggregation level
and the like) are used to determine the correspondence. Different
PRB pairs may have same correspondence, or different correspondence
may be defined for each PRB pair. The correspondence may be
cell-specific; for example, the base station may notify all UEs in
a cell by using broadcast signaling, which means that all the UEs
in the cell run according to same correspondence. The
correspondence may also be UE-specific; for example, the base
station may notify a specific UE by using RRC signaling, which
means that different UEs may have different correspondence.
[0155] According to the embodiment of the present invention, in
order to allocate different DMRS ports to candidate E-PDCCHs at a
same start position but different aggregation levels, eCCEs may be
sorted firstly; for example, eCCEs in a PRB pair may be numbered
firstly, and eCCEs in a next PRB pair may be numbered subsequently;
that is to say, an eCCE with an index i corresponds to the (i mod
K).sup.th eCCE in the .left brkt-bot.i/K.right brkt-bot..sup.th
E-PDCCH PRB pair, where K is the quantity of eCCEs divided in each
PRB pair. The embodiment of the present invention is not limited to
this numbering method.
[0156] Then, based on the eCCE numbering, a DMRS port corresponding
to each eCCE is defined sequentially; for example, when the
quantity of available DMRS ports is P, eCCEs may be defined to use
reference signals at the P DMRS ports sequentially and circularly.
In LTE release 11, P is equal to 4; that is to say, DMRS ports 7,
8, 9 and 10 may be used as E-PDCCH reference signal ports.
Therefore, for a UE, a DMRS port corresponding to the i.sup.th eCCE
may be defined as 7+(i+.sigma.)mod P, where .sigma. is a fixed
value, for example, 0; optionally, .sigma. is a cell-specific
parameter; optionally, .sigma. is a specific parameter specific to
each transmission point in a cell in coordinated multi-point
transmission; and optionally, .sigma. is a UE-specific
parameter.
[0157] Finally, based on the correspondence between eCCEs and DMRS
ports, a DMRS port that an E-PDCCH at each aggregation level uses
is defined, and it is ensured that candidate E-PDCCHs at a same
start position but different aggregation levels use different DMRS
ports. For example, when the aggregation level is L=2.sup.m-1 (m=1,
2, 3, 4), each candidate E-PDCCH may be defined to use a DMRS port
mapped to the m.sup.th eCCE to send a reference signal.
[0158] FIG. 9B and FIG. 9C are examples of allocating a DMRS port
to a candidate E-PDCCH.
[0159] Referring to FIG. 9B, assuming that one RBG includes two PRB
pairs, and each PRB pair is divided into 4 eCCEs, according to the
foregoing method, for a UE, eCCEs use DMRS ports 7, 8, 9 and 10
sequentially and circularly. For aggregation level 1, a DMRS port
mapped to an eCCE included in a candidate E-PDCCH is used; for
aggregation level 2, a DMRS port mapped to a second eCCE included
in a candidate E-PDCCH is used, which means that DMRS ports 8 and
10 may be used; for aggregation level 4, a DMRS port mapped to a
third eCCE included in a candidate E-PDCCH is used, which means
port 9 is always used; and for aggregation level 8, a DMRS port
mapped to a fourth eCCE included in a candidate E-PDCCH is used,
which means port 10 is always used. When a candidate E-PDCCH
crosses more than one PRB pair, a DMRS port determined according to
the foregoing method is also configured to bear a reference signal
on multiple PRB pairs mapped to the candidate E-PDCCH, for example,
when the aggregation level is 8.
[0160] Referring to FIG. 9C, assuming that one RBG includes three
PRB pairs, and each PRB pair is divided into 3 eCCEs, according to
the foregoing method, for a UE, it is still assumed that eCCEs use
DMRS ports 7, 8, 9 and 10 sequentially and circularly. For
aggregation level 1, a DMRS port mapped to an eCCE included in a
candidate E-PDCCH is used; for aggregation level 2, a DMRS port
mapped to a second eCCE included in a candidate E-PDCCH is used,
which means that DMRS ports 8 and 10 may be used; for aggregation
level 4, a DMRS port mapped to a third eCCE included in a candidate
E-PDCCH is used, which means port 9 is always used; and for
aggregation level 8, a DMRS port mapped to a fourth eCCE included
in a candidate E-PDCCH is used, which means port 10 is always used.
When a candidate E-PDCCH crosses more than one PRB pair, a DMRS
port determined according to the foregoing method is further
configured to bear a reference signal on multiple PRB pairs mapped
to the candidate E-PDCCH, for example, when the aggregation level
is 2, 4 and 8.
[0161] 930: The base station sends the E-PDCCH to the UE in a
subframe, and sends a PDSCH scheduled by the PDCCH to the UE.
[0162] When sending the E-PDCCH, the base station sends a reference
signal of the E-PDCCH to the UE by using the determined reference
signal port, where the E-PDCCH and the PDSCH invoked by the E-PDCCH
are frequency-division multiplexed; and E-PDCCHs at a same start
position but different aggregation levels correspond to different
reference signal ports.
[0163] 940: In a blind detection process, the UE performs channel
estimation according to the reference signal, so as to demodulate
the candidate E-PDCCH.
[0164] Assuming that the base station sends an E-PDCCH at
aggregation level 2 and sends a reference signal by using DMRS port
8, when blindly detecting each candidate E-PDCCH at aggregation
level 1, the UE tries to perform channel estimation based on DMRS
port 7 and demodulate the E-PDCCH; however, in fact, the base
station does not send the reference signal to the UE by using DMRS
port 7; it is quite clear that the demodulated output is some
random noise, so that CRC check is not possible to be successful,
thereby avoiding that the UE mixes up candidate E-PDCCHs at
different aggregation levels. This method also solves the foregoing
problem that a start position of an E-PDCCH is judged incorrectly
and the problem that E-PDCCHs at a same start position but
different aggregation levels are mixed up.
[0165] 950: If detecting its own E-PDCCH, the UE demodulates a
corresponding PDSCH according to the downlink control information
in the E-PDCCH, and feeds back in the uplink according to whether
the PDSCH demodulation is correct. 950 in FIG. 9 is similar to 850
in FIG. 8, and is not described here any further.
Embodiment 9
[0166] FIG. 10 is a schematic flowchart of a process for
transmitting downlink control information according to Embodiment 9
of the present invention. Embodiment 9 elaborates one or more steps
of the methods in Embodiment 5 and Embodiment 6.
[0167] In order to support multiplexing of an E-PDCCH and a PDSCH,
another problem to be solved is how to configure reference signals
of the E-PDCCH and the PDSCH. One situation is that the E-PDCCH and
the PDSCH are multiplexed in one PRB pair, where because the
reference signal of the E-PDCCH and the PDSCH are sent on a same
PRB pair, the reference signal of the E-PDCCH may possibly be used
to demodulate the PDSCH. Another situation is that the E-PDCCH and
the PDSCH are multiplexed in different PRB pairs of a same RBG;
here, although a PRB pair where the E-PDCCH is located does not
transmit the PDSCH, it is possible that channel estimation of the
reference signal of the E-PDCCH is used to enhance, by means of
interpolation, channel estimation accuracy of a PRB pair where the
PDSCH is located. Under both the two situations, a method for
multiplexing the reference signals of the E-PDCCH and the PDSCH
needs to be defined.
[0168] Specifically, when a rank of the PDSCH is one of 5, 6 and 7,
a DMRS port of at least a part of data flows of the PDSCH is
expanded in time by using a walsh code with a length of 4. However,
in order to ensure channel estimation performance of an E-PDCCH, a
reference signal of the E-PDCCH uses DMRS ports 7, 8, 9 and 10,
where the four DMRS ports may be processed based on a time
extension of walsh codes with a length of 2. Therefore, when the
reference signals of the E-PDCCH and the PDSCH are multiplexed, a
problem needs to be solved that walsh codes used by the E-PDCCH and
the PDSCH have different lengths.
[0169] In release 10, a maximum rank available for PDSCH
transmission is 8; a PDSCH DMRS port is mapped to two RE sets
bearing a reference signal, and these two sets are multiplexed
based on FDM/TDM, and may multiplex at most four DMRS ports on each
RE set. DMRS ports 7, 8, 11 and 13 are multiplexed in a CMD
multiplexing mode on a first RE set, while DMRS ports 9, 10, 12 and
14 are multiplexed in a CMD multiplexing mode on a second RE
set.
[0170] Referring to Table 1, Table 1 shows walsh codes used by the
foregoing 8 DMRS ports respectively. Walsh codes of the four DMRS
ports in the first RE set are used as an example, the first two
elements and the last two elements of walsh codes of DMRS ports 7
and 8 are orthogonal respectively, so that DMRS ports 7 and 8 can
be processed based on an orthogonal time extension with a length of
2; the first two elements and the last two elements of walsh codes
of DMRS ports 7 and 13 are also orthogonal respectively, so that
DMRS ports 7 and 13 can also be processed based on an orthogonal
time extension with a length of 2. However, neither the first two
elements nor the last two elements of walsh codes of DMRS ports 7
and 11 are orthogonal, but only an entirety of the four elements is
orthogonal; and therefore, the two ports can only be processed
based on an orthogonal time extension with a length of 4; if the UE
still processes the ports according to an orthogonal time extension
with a length of 2, great interference will be caused. Similarly,
DMRS ports 8 and 11 can be processed based on an orthogonal time
extension with a length of 2, while DMRS ports 8 and 13 can only be
processed according to an orthogonal time extension with a length
of 4.
TABLE-US-00001 TABLE 1 Antenna port p [ w.sub.p(0) w.sub.p(1)
w.sub.p(2) w.sub.p(3)] 7 [+1 +1 +1 +1] 8 [+1 -1 +1 -1] 9 [+1 +1 +1
+1] 10 [+1 -1 +1 -1] 11 [+1 +1 -1 -1] 12 [-1 -1 +1 +1] 13 [+1 -1 -1
+1] 14 [-1 +1 +1 -1]
[0171] In order that a DMRS port with respect to an E-PDCCH is
processed based on an orthogonal time extension with a length of 2,
and also that, when a PDSCH with a rank of 5, 6 or 7 is scheduled
by the E-PDCCH, a DMRS port with respect to a PDSCH is processed
based on an orthogonal time extension with a length of 4, the
present invention proposes the following limitation on the DMRS
ports of the PDSCH; that is to say, when a DMRS port occupied by
the E-PDCCH of the UE is v, a DMRS port p(v) is defined not to be
used to demodulate the PDSCH, or another DMRS port is needed to
replace the p(v), so that a reference signal port of the E-PDCCH
and a reference signal port of the PDSCH are processed based on
orthogonal time extensions with different lengths, and that the
E-PDCCH and the PDSCH can be multiplexed normally. Particularly,
p(v) is defined as follows:
p ( v ) = { 11 , v = 7 13 , v = 8 12 , v = 9 14 , v = 10 .
##EQU00006##
[0172] When the rank of the PDSCH is equal to 8, it may be
considered not to support multiplexing of the reference signals of
the E-PDCCH and the PDSCH. When the rank of the PDSCH is less than
or equal to 4, the E-PDCCH and the PDSCH both use DMRS ports 7, 8,
9 and 10; as the four DMRS ports are all based on an orthogonal
time extension with a length of 2, a problem that a DMRS port is
not available as a result of another DMRS port does not exist.
[0173] 1010: A base station performs CRC check code addition,
scrambling, encoding and rate matching on downlink control
information of a UE, so as to obtain modulation symbols of a PDCCH.
1010 of FIG. 10 is similar to 810 of FIG. 8, and is not described
here any further.
[0174] 1020: The base station performs physical resource mapping on
an E-PDCCH and a PDSCH, and allocates reference signal ports of the
E-PDCCH and the PDSCH, where the E-PDCCH and the PDSCH are
frequency-division multiplexed in a same PRB pair or in different
PRB pairs of a same RBG. According to the embodiment of the present
invention, two methods for allocating reference signal ports of an
E-PDCCH and a PDSCH are provided.
[0175] A first method is to adjust, according to a DMRS port
occupied by the E-PDCCH, a DMRS port of the PDSCH defined in LTE
release 10. A principle of the method is to maximally multiplex
PDSCH DMRS ports already defined in release 10; in other words,
only a port that affects a DMRS port occupied by the E-PDCCH is not
used; for example, when the E-PDCCH uses DMRS port 7, the PDSCH
will not use DMRS port 11.
[0176] When the rank is less than or equal to 4, for transmission
of a PDSCH, the definition of PDSCH DMRS ports in release 10 can be
completely reused. Specifically, if a DMRS port used by an E-PDCCH
is included in DMRS ports of a currently scheduled PDSCH, the DMRS
port may also be configured to demodulate the E-PDCCH and the
PDSCH; if the DMRS port used by the E-PDCCH is not included in the
DMRS ports of the currently scheduled PDSCH, the DMRS port is only
configured to demodulate the E-PDCCH. Optionally, if the definition
of the PDSCH DMRS port in release 10 is followed, for the currently
allocated PDSCH, the DMRS port used by the E-PDCCH is not included
in the DMRS port of the currently scheduled PDSCH, but on a
time-frequency resource where the DMRS port used by the E-PDCCH is
located, another DMRS port based on CDM multiplexing is occupied by
a reference signal of the PDSCH; here, the DMRS port used by the
E-PDCCH may be used to replace another DMRS port on a same
time-frequency resource to demodulate the PDSCH.
[0177] When the rank is 5, 6 or 7, and a DMRS port that the base
station uses to send the E-PDCCH to the UE is v, according to the
definition of the PDSCH DMRS port in release 10, if a DMRS port
needed by the currently scheduled PDSCH is p(v), the p(v) is
replaced with another DMRS port. Three preferred methods are
described as follows, but the present invention is not limited to
the three methods. When the rank is 5 or 6, the p(v) is replaced
with another DMRS port using a same RE set as the p(v), that is,
DMRS port p(v)+2; when the rank is 7, the p(v) is replaced with
DMRS port 14. Optionally, when the rank is 5, 6 or 7, the p(v) is
uniformly replaced with DMRS port 14. Optionally, when the rank R
is 5, 6 or 7, the p(v) is uniformly replaced with DMRS port
7+R.
[0178] A second method is to use, according to the DMRS port v
occupied by the E-PDCCH and the rank R of the currently scheduled
PDSCH, R continuous DMRS ports starting from port v as PDSCH
reference signal ports.
[0179] When the rank is less than or equal to 4, DMRS port
7+(v-7+r)mod 4 (r=0, . . . , R-1), may be used as a PDSCH reference
signal port; that is to say, port 7+(v-7+r)mod 4 replaces PDSCH
DMRS port 7+r defined in release 10. This method ensures that all
E-PDCCH DMRS ports can be multiplexed for PDSCH demodulation.
Optionally, when the rank is 2, in order to avoid extra resource
overhead which results from that two DMRS ports are respectively
mapped to two RE sets bearing a reference signal, an improved
method may be used that, when the rank is 3 or 4, the foregoing
method is still used; in other words, DMRS port 7+(v-7+r)mod 4
(r=0, . . . , R-1) may be used as the PDSCH reference signal port;
however, when the rank is 2, two PDSCH DMRS ports are limited to be
mapped to a same RE set; that is to say, DMRS ports v and
v+(-1).sup.(v-7)mod 2 are used to transmit the PDSCH.
[0180] When the rank R is 5, 6 and 7, if the DMRS port that the
base station uses to send the E-PDCCH to the UE is v, R continuous
ports starting from DMRS port v are used; that is to say, DMRS port
7+(v-7+r)mod 8 (r=0, . . . , R-1) are used as PDSCH reference
signal ports; and if the R DMRS ports include p(v), p(v) is
replaced with another DMRS port. Two preferred methods are
described as follows, but the present invention is not limited to
the two methods. For example, when the rank is 5, 6 or 7, p(v) is
uniformly replaced with DMRS port 7+v mod 8. Optionally, when the
rank R is 5, 6 and 7, p(v) is uniformly replaced with DMRS port
7+(v-7+R)mod 8.
[0181] 1030: The base station sends the mapped PDCCH and PDSCH to
the UE.
[0182] The base station sends the reference signal of the E-PDCCH
by using a first reference signal port v. The base station sends a
reference signal of the PDSCH by using at least one second
reference signal port, and determines, according to the foregoing
reference signal port allocation method, not to use a second
reference signal port p(v) but to select another reference signal
port to send the reference signal of the PDSCH, so that a reference
signal port of the E-PDCCH and a reference signal port of the PDSCH
are processed based on orthogonal time extensions with different
lengths, where the first reference signal port is one of the at
least one second reference signal port.
[0183] 1040: The UE demodulates the E-PDCCH based on a channel
estimation result.
[0184] The UE receives the reference signal of the E-PDCCH which is
sent by the base station by using the first reference signal port v
and the reference signal of the PDSCH which is sent by the base
station by using at least one second reference signal port, where
the PDSCH is invoked by the E-PDCCH. The UE performs channel
estimation by using the reference signal of the E-PDCCH, so as to
demodulate the E-PDCCH, and performs channel estimation by using
the reference signal of the PDSCH, so as to demodulate the PDSCH.
The UE determines, according to the foregoing reference signal port
allocation method, not to use the reference signal of the PDSCH
sent by the second reference signal port p(v) but to select another
reference signal port to perform channel estimation, so that a
reference signal port of the E-PDCCH and a reference signal port of
the PDSCH are processed based on orthogonal time extensions with
different lengths, where the first reference signal port is one of
the at least one second reference signal port.
[0185] Similarly, the foregoing method for allocating reference
signal ports of the E-PDCCH and the PDSCH may be configured in the
UE; a specific method is similar to the method for allocating
reference signal ports of the E-PDCCH and the PDSCH at a base
station end, and is not described here any further.
[0186] 1050: If detecting its own E-PDCCH, the UE demodulates a
corresponding PDSCH according to the downlink control information
in the E-PDCCH, and feeds back in the uplink according to whether
the PDSCH demodulation is correct. 1050 in FIG. 10 is similar to
850 in FIG. 8, and is not described here any further.
[0187] The method for transmitting downlink control information
according to the embodiment of the present invention is described
above; with reference to FIG. 11 to FIG. 16, the following
respectively describes a base station, a UE, and a system, as well
as a corresponding storable medium and a corresponding computer
program product, according to embodiments of the present
invention.
Embodiment 10
[0188] FIG. 11 is a schematic structural diagram of a base station
1100 according to Embodiment 10 of the present invention. The base
station 1100 includes a mapping unit 1110 and a sending unit 1120.
The embodiment in FIG. 11 elaborates one or more steps of the
method in the embodiment in FIG. 2.
[0189] The mapping unit 1110 maps, according to an order of OFDM
symbols used by an E-PDCCH of a UE, the E-PDCCH sequentially to REs
used to transmit the E-PDCCH in each OFDM symbol. The sending unit
1120 sends the E-PDCCH to the UE by using the REs, where the
E-PDCCH and a PDSCH invoked by the E-PDCCH are frequency-division
multiplexed.
[0190] In the embodiment of the present invention, the E-PDCCH can
be mapped, according to the order of OFDM symbols used by the
E-PDCCH of the UE, sequentially to the REs used to transmit the
E-PDCCH in each OFDM symbol, so that different eCCEs will not
include a same E-PDCCH modulation symbol, thereby avoiding that the
UE judges a start position of the E-PDCCH incorrectly. In addition,
a problem that E-PDCCHs at a same start position but different
aggregation levels are mixed up is also solved.
[0191] According to the embodiment of the present invention, the
mapping unit 1110 maps, according to an order of L eCCEs allocated
to the E-PDCCH in each OFDM symbol, the E-PDCCH sequentially to REs
occupied by the L eCCEs in the OFDM symbol, where L is an
integer.
[0192] Optionally, as another embodiment, the mapping unit 1110
maps, according to an order of subcarriers in each OFDM symbol, the
E-PDCCH sequentially to REs occupied by L eCCEs allocated to the
E-PDCCH.
[0193] For operations executed by means of hardware of the base
station 1100 or cooperation of hardware and corresponding software
of the base station 1100, reference may be made to the
corresponding method in Embodiment 1, for example, 210 and 220 of
the method in the foregoing Embodiment 1. However, to avoid
repetition, the steps are not described here any further.
[0194] In addition, a computer readable media (or medium) is
further provided, including a computer readable instruction that
performs the following operation when executed, that is, an
operation of executing 210 and 220 of the method the foregoing
Embodiment 1.
[0195] In addition, a computer program product is further provided,
including the foregoing computer readable medium.
Embodiment 11
[0196] FIG. 12 is a schematic structural diagram of a UE 1200
according to Embodiment 11 of the present invention. The UE 1200
includes a receiving unit 1210 and an extracting unit 1220. The
embodiment in FIG. 12 elaborates one or more steps of the method in
the embodiment in FIG. 3.
[0197] The receiving unit 1210 receives a downlink subframe from a
base station. The extracting unit 1220 extracts, in a blind
detection process according to an order of OFDM symbols used by a
candidate E-PDCCH in the downlink subframe, modulation symbols of
the candidate E-PDCCH sequentially from REs used to transmit the
candidate E-PDCCH in each OFDM symbol, and performs decoding and
CRC check on the candidate E-PDCCH, where the E-PDCCH of the UE and
a PDSCH invoked by the E-PDCCH of the UE are frequency-division
multiplexed.
[0198] In the embodiment of the present invention, the E-PDCCH can
be mapped, according to the order of OFDM symbols used by the
E-PDCCH of the UE, sequentially to the REs used to transmit the
E-PDCCH in each OFDM symbol, so that different eCCEs will not
include a same E-PDCCH modulation symbol, thereby avoiding that the
UE judges a start position of the E-PDCCH incorrectly. In addition,
a problem that E-PDCCHs at a same start position but different
aggregation levels are mixed up is also solved.
[0199] According to the embodiment of the present invention, the
extracting unit 1220 sequentially extracts, according to an order
of L eCCEs allocated to the candidate E-PDCCH in each OFDM symbol,
modulation symbols of the candidate E-PDCCH from REs occupied by
the L eCCEs in the OFDM symbol, where L is an integer.
[0200] Optionally, as another embodiment, the extracting unit 1220
sequentially extracts, according to an order of subcarriers in each
OFDM symbol, the E-PDCCH from REs occupied by L eCCEs allocated to
the E-PDCCH.
[0201] For operations executed by means of hardware of the UE 1200
or cooperation of hardware and corresponding software of the UE
1200, reference may be made to the corresponding method in
Embodiment 2, for example, 310 and 320 of the method in the
foregoing Embodiment 2. However, to avoid repetition, the steps are
not described here any further.
[0202] In addition, a computer readable media (or medium) is
further provided, including a computer readable instruction that
performs the following operation when executed, that is, an
operation of executing 310 and 320 of the method in the foregoing
Embodiment 2.
[0203] Further, a computer program product is further provided,
including the foregoing computer readable medium.
Embodiment 12
[0204] FIG. 13 is a schematic structural diagram of a base station
1300 according to Embodiment 12 of the present invention. The base
station 1300 includes a determining unit 1310 and a sending unit
1320. The embodiment in FIG. 13 elaborates one or more steps of the
method in the embodiment in FIG. 4.
[0205] The determining unit 1310 is configured to determine a
reference signal port according to an aggregation level of an
E-PDCCH of a UE, where E-PDCCHs at different aggregation levels
correspond to different reference signal ports, and the aggregation
level indicates the quantity of eCCEs included in the E-PDCCH. The
sending unit 1320 is configured to send the E-PDCCH to the UE in a
subframe, and send a reference signal of the E-PDCCH to the UE by
using the determined reference signal port, where the E-PDCCH and a
PDSCH invoked by the E-PDCCH are frequency-division
multiplexed.
[0206] According to the embodiment of the present invention,
reference signals of E-PDCCHs at different eCCE aggregation levels
can be sent by using different DMRS ports, so that the UE can
demodulate, according to a dedicated DMRS reference signal of an
E-PDCCH at each aggregation level, the E-PDCCH correctly, thereby
avoiding a problem that the UE judges a start position of the
E-PDCCH incorrectly. In addition, a problem that E-PDCCHs at a same
start position but different aggregation levels are mixed up is
also solved.
[0207] According to the embodiment of the present invention,
E-PDCCHs at a same start position but different aggregation levels
in the subframe correspond to different reference signal ports.
[0208] Further, the determining unit 1310 may be specifically
configured to select, according to the aggregation level of the
physical downlink control channel E-PDCCH of the UE, one or more
reference signal ports from a reference signal port set
corresponding to the aggregation level as a reference signal port
corresponding to the aggregation level, where reference signal
ports selected for E-PDCCHs at different aggregation levels are
different.
[0209] Further, the at a same start position in the subframe may
include: at a same start position in a same physical resource block
pair or different physical resource block pairs.
[0210] Further, E-PDCCHs, corresponding to different user
equipments UEs, at a same aggregation level, and occupying a same
physical resource, correspond to different reference signal
ports.
[0211] For operations executed by means of hardware of the base
station 1300 or cooperation of hardware and corresponding software
of the base station 1300, reference may be made to the
corresponding method in Embodiment 3, for example, 410 and 420 of
the method in the foregoing Embodiment 3. However, to avoid
repetition, the steps are not described here any further.
[0212] In addition, a computer readable media (or medium) is
further provided, including a computer readable instruction that
performs the following operation when executed, that is, an
operation of executing 410 and 420 of the method in the foregoing
Embodiment 3.
[0213] In addition, a computer program product is further provided,
including the foregoing computer readable medium.
Embodiment 13
[0214] FIG. 14 is a schematic structural diagram of a UE 1400
according to Embodiment 13 of the present invention. The UE 1400
includes a receiving unit 1410 and a demodulating unit 1420. The
embodiment in FIG. 14 elaborates one or more steps of the method in
the embodiment in FIG. 5.
[0215] The receiving unit 1410 receives, from a reference signal
port in a subframe, a reference signal of a candidate E-PDCCH sent
by a base station, where candidate E-PDCCHs at different
aggregation levels correspond to different reference signal ports,
and the aggregation level indicates the quantity of eCCEs included
in the candidate E-PDCCH. The demodulating unit 1420 performs
channel estimation according to the reference signal, so as to
demodulate the E-PDCCH, where the candidate E-PDCCH and a PDSCH
invoked by the candidate E-PDCCH are frequency-division
multiplexed.
[0216] According to the embodiment of the present invention,
reference signals of E-PDCCHs at different eCCE aggregation levels
can be sent by using different DMRS ports, so that the UE can
demodulate, according to a dedicated DMRS reference signal of an
E-PDCCH at each aggregation level, the E-PDCCH correctly, thereby
avoiding a problem that the UE judges a start position of the
E-PDCCH incorrectly. In addition, a problem that E-PDCCHs at a same
start position but different aggregation levels are mixed up is
also solved.
[0217] According to the embodiment of the present invention,
candidate E-PDCCHs at a same start position but different
aggregation levels in the subframe correspond to different
reference signal ports.
[0218] For operations executed by means of hardware of the UE 1400
or cooperation of hardware and corresponding software of the UE
1400, reference may be made to the corresponding method in
Embodiment 4, for example, 510 and 520 of the method in the
foregoing Embodiment 4. However, to avoid repetition, the steps are
not described here any further.
[0219] In addition, a computer readable media (or medium) is
further provided, including a computer readable instruction that
performs the following operation when executed, that is, an
operation of executing 510 and 520 of the method in the foregoing
Embodiment 4.
[0220] In addition, a computer program product is further provided,
including the foregoing computer readable medium.
Embodiment 14
[0221] FIG. 15 is a schematic structural diagram of a base station
1500 according to Embodiment 14 of the present invention. The base
station 1500 includes a sending unit 1510 and a determining unit
1520. The embodiment in FIG. 15 elaborates one or more steps of the
method in the embodiment in FIG. 6.
[0222] The sending unit 1510 sends a reference signal of the
E-PDCCH by using a first reference signal port v, and send a
reference signal of the PDSCH by using at least one second
reference signal port. The determining unit 1520 determines not to
use a second reference signal port p(v) to send the reference
signal of the PDSCH, so that a reference signal port of the E-PDCCH
and a reference signal port of the PDSCH are processed based on
orthogonal time extensions with different lengths, where the
E-PDCCH and the PDSCH are frequency-division multiplexed, the first
reference signal port is one of the at least one second reference
signal port, and v and p(v) are serial numbers of the reference
signal ports.
[0223] According to the embodiment of the present invention, when
using a reference signal port to send a reference signal of a PDSCH
results that a reference signal port of an E-PDCCH and the
reference signal port of the PDSCH cannot be processed based on
orthogonal time extensions with different lengths, the reference
signal port may be not used to send the reference signal of the
PDSCH, so that the reference signal of the PDSCH and a reference
signal of the E-PDCCH are multiplexed normally.
[0224] According to the embodiment of the present invention, the at
least one second reference signal port includes at least one of
PDSCH reference signal ports 7, 8, 9, 10, 11, 12, 13 and 14 defined
in LTE release 10, the first reference signal port includes an
E-PDCCH reference signal port 7, 8, 9, or 10 defined in LTE release
10, and
p ( v ) = { 11 , v = 7 13 , v = 8 12 , v = 9 14 , v = 10 .
##EQU00007##
[0225] According to the embodiment of the present invention, when a
rank R of the PDSCH is less than or equal to 4, the sending unit
1510 sends the reference signal of the PDSCH by using a PDSCH
reference signal port defined in LTE release 10; or when the rank R
of the PDSCH is one of 5, 6 and 7, the sending unit 1510 sends the
reference signal of the PDSCH by using a PDSCH reference signal
port defined in LTE release 1, and when needing to send the
reference signal of the PDSCH by using the second reference signal
port p(v) to, the sending unit 1510 replaces the reference signal
port p(v) with another available reference signal port among the
PDSCH reference signal ports, where R is an integer.
[0226] Optionally, as another embodiment, when a rank R of the
PDSCH is less than or equal to 4, the sending unit 1510 may send
the reference signal of the PDSCH by using R reference signal ports
7+(v-7+r)mod 4 starting from the reference signal port v, where
r=0, . . . , R-1, and R is an integer; or, when the rank R of the
PDSCH is equal to one of 5, 6 and 7, the sending unit 1510 may send
the reference signal of the PDSCH by using R reference signal ports
7+(v-7+r) mod 8 starting from the reference signal port v, and when
the R reference signal ports include the reference signal port
p(v), replace the reference signal port p(v) with another reference
signal port among the PDSCH reference signal ports, where r=0, . .
. , R-1.
[0227] For operations executed by means of hardware of the base
station 1500 or cooperation of hardware and corresponding software
of the base station 1500, reference may be made to the
corresponding method in Embodiment 5, for example, 610 and 620 of
the method in the foregoing Embodiment 5. However, to avoid
repetition, the steps are not described here any further.
[0228] In addition, a computer readable media (or medium) is
further provided, including a computer readable instruction that
performs the following operation when executed, that is, an
operation of executing 610 and 620 of the method in the foregoing
Embodiment 5.
[0229] In addition, a computer program product is further provided,
including the foregoing computer readable medium.
Embodiment 15
[0230] FIG. 16 is a schematic structural diagram of a UE 1600
according to Embodiment 15 of the present invention. The UE 1600
includes a receiving unit 1610, a demodulating unit 1620, and a
determining unit 1630. The embodiment in FIG. 16 elaborates one or
more steps of the method in the embodiment in FIG. 7.
[0231] The receiving unit 1610 is configured to receive a reference
signal of an E-PDCCH which is sent by a base station by using a
first reference signal port v and a reference signal of a PDSCH
which is sent by the base station by using at least one second
reference signal port, where the PDSCH is invoked by the E-PDCCH.
The demodulating unit 1620 is configured to perform channel
estimation by using the reference signal of the E-PDCCH, so as to
demodulate the E-PDCCH, and perform channel estimation by using the
reference signal of the PDSCH, so as to demodulate the PDSCH. The
determining unit 1630 is configured to determine not to use the
reference signal of the PDSCH sent by the second reference signal
port p(v) to perform channel estimation, so that a reference signal
port of the E-PDCCH and a reference signal port of the PDSCH are
processed based on orthogonal time extensions with different
lengths, where the E-PDCCH and the PDSCH are frequency-division
multiplexed, the first reference signal port is one of the at least
one second reference signal port, and v and p(v) are serial numbers
of the reference signal ports.
[0232] According to the embodiment of the present invention, the at
least one second reference signal port includes at least one of
PDSCH reference signal ports 7, 8, 9, 10, 11, 12, 13 and 14 defined
in LTE release 10, the first reference signal port includes an
E-PDCCH reference signal port 7, 8, 9, or 10 defined in LTE release
10, and
p ( v ) = { 11 , v = 7 13 , v = 8 12 , v = 9 14 , v = 10 .
##EQU00008##
[0233] According to the embodiment of the present invention, when a
rank R of the PDSCH is less than or equal to 4, the demodulating
unit 1620 performs channel estimation by using a reference signal
of the PDSCH sent by a PDSCH reference signal port defined in LTE
release 10; or when the rank R of the PDSCH is one of 5, 6 and 7,
the demodulating unit 1620 performs channel estimation by using a
reference signal of the PDSCH sent by a PDSCH reference signal port
defined in LTE release 10, and when the UE needs to perform channel
estimation by using the reference signal of the PDSCH sent by the
second reference signal port p(v), replaces the reference signal
port p(v) with another available reference signal port among the
PDSCH reference signal ports to perform channel estimation, where R
is an integer.
[0234] Optionally, as another embodiment, when a rank R of the
PDSCH is less than or equal to 4, the demodulating unit 1620 may
perform channel estimation by using reference signals of the PDSCH
sent by R reference signal ports 7+(v-7+r) mod 4 starting from the
reference signal port v, where r=0, . . . , R-1, and R is an
integer; or, when the rank R of the PDSCH is equal to one of 5, 6
and 7, the demodulating unit 1620 may to perform channel estimation
by using reference signals of the PDSCH sent by R reference signal
ports 7+(v-7+r)mod 8 starting from the reference signal port v, and
when the R reference signal ports include the reference signal port
p(v), replace the reference signal port p(v) with another reference
signal port among the PDSCH reference signal ports to perform
channel estimation, where r=0, . . . , R-1.
[0235] For operations executed by means of hardware of the UE 1600
or cooperation of hardware and corresponding software of the UE
1600, reference may be made to the corresponding method in
Embodiment 6, for example, 710, 720 and 730 of the method in the
foregoing Embodiment 6. However, to avoid repetition, the steps are
not described here any further.
[0236] In addition, a computer readable media (or medium) is
further provided, including a computer readable instruction that
performs the following operation when executed, that is, an
operation of executing 710 and 720 of the method in the foregoing
Embodiment 6.
[0237] In addition, a computer program product is further provided,
including the foregoing computer readable medium.
[0238] A person of ordinary skill in the art may recognize that
units and algorithmic steps of examples described with reference to
the embodiments disclosed herein may be implemented by means of
electronic hardware or combination of computer software and
electronic hardware. Whether the functions are executed by hardware
or software depends on particular applications and design
constraint conditions of the technical solutions. A person skilled
in the art may use different methods to implement the described
functions for each particular application, but it should not be
considered that the implementation goes beyond the scope of the
present invention.
[0239] A person skilled in the art can clearly understand that, for
convenience and conciseness of description, for specific working
processes of the described systems, apparatuses and units,
reference may be made to corresponding processes in the foregoing
method embodiments, which will not be described here any
further.
[0240] In the several embodiments provided in the present
application, it should be understood that the disclosed system,
apparatus, and method may be implemented in other manners. For
example, the described apparatus embodiment is merely exemplary.
For example, the unit division is merely logical function division
and may be other division in actual implementation. For example, a
plurality of units or components may be combined or integrated into
another system, or some features may be ignored or not performed.
In addition, the displayed or discussed mutual couplings or direct
couplings or communication connections may be implemented through
some interfaces. The indirect couplings or communication
connections between the apparatuses or units may be implemented in
electronic, mechanical, or other forms.
[0241] The units described as separated parts may be or may not be
physically separate, and the parts displayed as units may or may
not be physical units, may be located in one position, or may be
distributed on a plurality of network units. A part of or all of
the units may be selected according to actual needs to achieve the
objectives of the solutions of the embodiments.
[0242] In addition, the functional units of each embodiment in the
present invention may be integrated in a physical unit, or each of
the units may exist alone physically, or two or more units may be
integrated into one unit.
[0243] When the functions are implemented in a form of a software
functional unit and sold or used as an independent product, the
functions may be stored in a computer-readable storage medium.
Based on such an understanding, the technical solutions of the
present invention essentially, or the part contributing to the
prior art, or a part of the technical solutions may be implemented
in a form of a software product. The computer software product is
stored in a storage medium and includes several instructions for
instructing a computer device (which may be a personal computer, a
server, a network device, or the like) to perform all or a part of
the steps of the methods described in the embodiments of the
present invention. The foregoing storage medium includes: any
mediums that can store program code, such as a USB flash drive, a
removable hard disk, a read-only memory (ROM), a random access
memory (RAM), a magnetic disk, or an optical disc.
Embodiment 16
[0244] In LTE R-11, the quantity of aggregation levels
corresponding to a UE is M; if E-PDCCHs at N aggregation levels
among the M aggregation levels are mixed up, correct reception of
an E-PDCCH or a PDSCH by the UE will be affected, where M is not
less than N, and M and N are integers.
[0245] Downlink control channels E-PDCCHs have M aggregation
levels, where each aggregation level of N aggregation levels
thereof corresponds to a reference signal port set. With respect to
a UE, for each aggregation level of the N aggregation levels, a
base station selects a reference signal port from a reference
signal port set corresponding to the aggregation level as a
reference signal port corresponding to the aggregation level;
reference signal ports selected for the N aggregation levels of the
UE are different from each other; and the reference signal port set
at least includes one reference signal port.
[0246] The base station sends the E-PDCCH to the UE in a subframe,
and sends a reference signal of the E-PDCCH to the UE by using a
determined reference signal port,
[0247] where N is less than or equal to M.
[0248] For E-PDCCH transmission, each physical resource block pair
may include 2 or 4 physical eCCEs, where each physical eCCE bears
eCCEs of one ePDCCH, as shown in FIG. 17. An E-PDCCH at aggregation
level L includes L logical eCCEs; the L logical eCCEs are mapped to
L physical eCCEs; and control information of the E-PDCCH is
transmitted on the L physical eCCEs.
[0249] If each PRB pair includes 4 eCCEs, according to a size of
control signaling, the numbers of PRB pairs occupied by an ePDCCH
corresponding to aggregation levels 2, 4, 8, 12, 16 and above 16
are respectively 1, 1, 2, 3, 4 and above 4. For example, when a UE
detects an E-PDCCH at aggregation level 8, if the first 4 eCCEs are
detected successfully, the UE regards the aggregation level of the
E-PDCCH as 4 and the quantity of PRB pairs occupied as 1. In fact,
the quantity of PRB pairs occupied by the E-PDCCH is 2. In this
case, the UE may possibly regard the rest 4 eCCEs as resources to
transmit a PDSCH, and receive the PDSCH on the rest 4 eCCEs, which
may cause incorrect reception of the PDSCH. Similarly, if each PRB
pair includes two eCCEs, according to a size of control signaling,
the numbers of PRB pairs occupied by an ePDCCH corresponding to
aggregation levels 2, 4, 8, 12, 16 and above 16 are respectively 1,
2, 4, 6, 8 and above 8. When the E-PDCCH is received, the foregoing
problem that aggregation levels are mixed up will also occur.
Aggregation levels that are possible to be mixed up for a UE are
possibly N of the aggregation levels 2, 4, 8, 12, 16 and above 16,
and each aggregation level of the N aggregation levels corresponds
to a reference signal port set. A reference signal port
corresponding to aggregation level L among the N aggregation levels
of the UE is one or more reference signal ports selected from a
reference signal port set corresponding to the aggregation level L.
Reference signal ports selected for the N aggregation levels of the
UE are different from each other.
[0250] To be specific, for example:
[0251] If each physical resource block includes four physical
eCCEs, a reference signal port set corresponding to aggregation
level 2 may be set 1, a reference signal port set corresponding to
aggregation level 4 may be set 2, and a reference signal port set
corresponding to aggregation level 8 may be set 3. Reference signal
ports included in each set may be completely different, partially
the same or the completely same. The quantity of reference signal
ports respectively included in set 1, set 2 and set 3 is at least
1. For any UE, a reference signal port selected from set 1 is r, a
reference signal port selected from set 2 is s, and a reference
signal port selected from set 3 is t. A reference signal port
corresponding to aggregation level 2 of the UE is r, a reference
signal port corresponding to aggregation level 4 of the UE is s,
and a reference signal port corresponding to aggregation level 8 of
the UE is t, where r, s and t are different from each other. For
example, set 1 is {reference signal port 7, reference signal port
8, reference signal port 9, reference signal port 10}, set 2 is
{reference signal port 8, reference signal port 9}, and set 3 is
{reference signal port 7, reference signal port 10}. As shown in
FIG. 18, for UE1 (or all UEs in cell 1, aggregation level 2
corresponds to reference signal port 7 or 9, aggregation level 4
corresponds to reference signal port 8, and aggregation level 8
corresponds to reference signal port 10; for UE2 (or all UEs in
cell 2, aggregation level 2 corresponds to reference signal port 8
or 10, aggregation level 4 corresponds to reference signal port 9,
and aggregation level 8 corresponds to reference signal port 7. It
can be seen that, if reference signal ports are configured in such
a manner, for a same UE, aggregation levels 2, 4 and 8 correspond
to different reference signal ports, which can avoid the problem
that the aggregation levels are mixed up. Further, E-PDCCHs,
corresponding to different user equipments UEs, at a same
aggregation level, and occupying a same physical resource,
correspond to different reference signal ports, and can support
multi-user transmission. For example, for aggregation level 2,
physical resources that the first E-PDCCHs of UE1 and UE2 occupy
are eCCE0 and eCCE1, while physical resources that the second
E-PDCCHs of UE1 and UE2 occupy are eCCE2 and eCCE3. For aggregation
level 2, the first E-PDCCHs of UE1 and UE2 correspond to different
reference signal ports, so as to support simultaneous transmission
of UE1 and UE2 on eCCE0 and eCCE1; and the second E-PDCCHs of UE1
and UE2 correspond to different reference signal ports, so as to
support simultaneous transmission of UE1 and UE2 on eCCE2 and
eCCE3.
[0252] If each physical resource block includes two physical eCCEs,
a reference signal port set corresponding to aggregation level 2 is
set 1, a reference signal port set corresponding to aggregation
level 4 is set 2, and a reference signal port set corresponding to
aggregation level 8 is set 3. Reference signal ports included in
each set may be completely different, partially the same or
completely the same. The quantity of reference signal ports
respectively included in set 1, set 2 and set 3 is at least 1. For
any UE, a reference signal port selected from set 1 is r, a
reference signal port selected from set 2 is s, and a reference
signal port selected from set 3 is t. A reference signal port
corresponding to aggregation level 2 of the UE is r, a reference
signal port corresponding to aggregation level 4 of the UE is s,
and a reference signal port corresponding to aggregation level 8 of
the UE is t, where r, s and t are different from each other. For
example, set 1 is {reference signal port 7, reference signal port
10}, set 2 is {reference signal port 8, reference signal port 9},
and set 3 is {reference signal port 7, reference signal port 10}.
As shown in FIG. 19, for UE1 (or all UEs in cell 1, aggregation
level 2 corresponds to reference signal port 7, aggregation level 4
corresponds to reference signal port 9, and aggregation level 8
corresponds to a reference signal port 10; for UE2 (or all UEs in
cell 2, aggregation level 2 corresponds to reference signal port
10, aggregation level 4 corresponds to reference signal port 8, and
aggregation level 8 corresponds to reference signal port 7. It can
be seen that, if reference signal ports are configured in such a
manner, for a same UE, aggregation levels 2, 4 and 8 correspond to
different reference signal ports, which can avoid the problem that
the aggregation levels are mixed up. Further, E-PDCCHs,
corresponding to different user equipments UEs, at a same
aggregation level, and occupying a same physical resource,
correspond to different reference signal ports, and can support
multi-user transmission.
[0253] Further, that reference signal ports selected for the N
aggregation levels of the UE are different from each other may
specifically be: reference signal ports selected for E-PDCCHs at
the N aggregation levels of the UE, which are mapped to a same
physical resource start position are different from each other,
which may also be understood that, E-PDCCHs at a same start
position but different aggregation levels in the subframe
correspond to different reference signal ports.
[0254] Further, the at a same start position in the subframe may
include: at a same start position in a same physical resource block
pair or different physical resource block pairs. The "at a same
start position in the subframe" herein may all be understood as
above, and is not described any further.
[0255] As shown in FIG. 20, for UE1 and UE2, in a same PRB pair,
two E-PDCCHs are at aggregation level 2, where a first E-PDCCH is
mapped to eCCE0 and eCCE1, where eCCE0 is a start position; and a
second E-PDCCH is mapped to eCCE2 and eCCE3, where eCCE2 is a start
position. One E-PDCCH is at aggregation level 4, which is mapped to
eCCE0, eCCE1, eCCE2 and eCCE3, where eCCE0 is a start position. One
E-PDCCH is at aggregation level 8, which is mapped to eCCE0, eCCE1,
eCCE2 and eCCE3, as well as eCCE0, eCCE1, eCCE2 and eCCE3 of
another PRB pair, where eCCE0 is a start position.
[0256] Then, for UE1, reference signal ports selected for the two
E-PDCCHs at aggregation level 2 are reference signal ports 7 and 10
respectively, a reference signal port selected for the E-PDCCH at
aggregation level 4 is reference signal port 8, and a reference
signal port selected for the E-PDCCH at aggregation level 8 is
reference signal port 10. It can be seen that reference signal
ports selected for E-PDCCHs at aggregation levels 2, 4 and 8 and
mapped to a same physical resource start position (that is eCCE0 in
this embodiment) are respectively reference signal ports 7, 8 and
10, which are different from each other. For UE2, reference signal
ports selected for the two E-PDCCHs at aggregation level 2 are
reference signal ports 8 and 9 respectively, a reference signal
port selected for the E-PDCCH at aggregation level 4 is reference
signal port 9, and a reference signal port selected for the E-PDCCH
at aggregation level 8 is reference signal port 7. It can be seen
that reference signal ports selected for E-PDCCHs at aggregation
levels 2, 4 and 8 and mapped to a same physical resource start
position (that is eCCE0 in this embodiment) are respectively
reference signal ports 8, 9 and 7, which are different from each
other. The at a same physical resource start position may be
understood as at a same start position in the subframe. Further,
the at a same start position in the subframe includes: at a same
start position in a same physical resource block pair or different
physical resource block pairs. That is to say, the at a same start
position in the subframe may be at a same start position in
different PRB pairs or at a same start position in identical PRB
pairs. As shown in FIG. 21, physical resource position 1 is eCCE0
of PRB pair 1, physical resource position 2 is eCCE0 of PRB pair 2,
and physical resource position 3 is eCCE0 of PRB pair 3. A same
start position in different PRB pairs means that positions of the
PRB pairs are different, but start positions in the PRB pairs are
the same; for example, if one start position is physical resource
position 1, and another start position is physical resource
position 3, and it may be called at a same start position in
different PRB pairs. A same start position in identical PRB pairs
means that positions of PRB pairs are the same and start positions
in the PRB pairs are also the same; for example, if the two start
positions both are physical resource position 1 or the two start
positions both are physical resource position 3, it may be called
at a same start position in identical PRB pairs.
[0257] The methods of configuring a reference signal port set and
selecting a reference signal port from the reference signal port
set are shared by the base station and the UE, and may be defined
and configured by the system previously, or notified to the UE by
the base station, or obtained according to a parameter of the UE,
or the like.
[0258] Understandably, the selected reference signal ports are only
used for description; a person skilled in the art may deduce
another reference signal port set or an example of selecting a
reference signal port from the set, which is not limited in the
present invention.
[0259] It should be noted that, due to limited space, mutual
reference may be made to corresponding embodiments of the present
invention, and same content will not be described repetitively.
[0260] The foregoing descriptions are merely specific embodiments
of the present invention, but are not intended to limit the
protection scope of the present invention. Any variation or
replacement readily figured out by a person skilled in the art
within the technical scope disclosed in the present invention shall
fall within the protection scope of the present invention.
Therefore, the protection scope of the present invention shall be
subject to the protection scope of the claims.
* * * * *