U.S. patent number 9,271,279 [Application Number 13/891,162] was granted by the patent office on 2016-02-23 for channel state measurement and reporting.
This patent grant is currently assigned to Sharp Laboratories of America, Inc.. The grantee listed for this patent is Sharp Laboratories of America, Inc.. Invention is credited to Ahmad Khoshnevis, Shohei Yamada, Zhanping Yin.
United States Patent |
9,271,279 |
Khoshnevis , et al. |
February 23, 2016 |
**Please see images for:
( Certificate of Correction ) ** |
Channel state measurement and reporting
Abstract
A method for reporting uplink control information (UCI) on a
user equipment (UE) is described. A Type 2 channel state
information (CSI) report is generated for a CSI reference resource.
The Type 2 CSI report is sent to a base station. The Type 2 CSI
report is computed from a channel measurement based on a non-zero
power reference signal on a single subframe within a configured
CSI-RS resource associated with a CSI process.
Inventors: |
Khoshnevis; Ahmad (Portland,
OR), Yamada; Shohei (Camas, WA), Yin; Zhanping
(Vancouver, WA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Sharp Laboratories of America, Inc. |
Camas |
WA |
US |
|
|
Assignee: |
Sharp Laboratories of America,
Inc. (Camas, WA)
|
Family
ID: |
51864731 |
Appl.
No.: |
13/891,162 |
Filed: |
May 9, 2013 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20140334391 A1 |
Nov 13, 2014 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
72/0413 (20130101); H04L 5/0057 (20130101); H04W
24/08 (20130101); H04L 5/0078 (20130101); H04L
5/0048 (20130101); H04L 1/00 (20130101); H04W
24/10 (20130101); H04L 5/001 (20130101); H04L
5/14 (20130101); H04L 5/0023 (20130101) |
Current International
Class: |
H04W
4/00 (20090101); H04L 1/00 (20060101); H04W
72/04 (20090101); H04L 5/00 (20060101); H04L
5/14 (20060101) |
Field of
Search: |
;370/252-311,328-480
;375/224-260 ;455/452-562 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
"Evolved Universal Terrestrial Radio Access (E-UTRA); Physical
layer procedures (Release 11)", 3GPP TS 36.213 V11.2.0, 2013.02,
pp. 52-86. cited by applicant .
Samsung, "CQI Reference Resource Timing for LTE-A", 3GPP TSG RAN
WG1 #63bis, R1-110089, Jan. 2011, pp. 1-5. cited by applicant .
International Search Report issued for International Patent
Application No. PCT/JP2014-002461 on May 9, 2014. cited by
applicant .
3GPP TS 36.213 V9.1.0, Evolved Universal Terrestrial Radio Access
(E-UTRA) Physical Layer Procedures, (Release 9), Mar. 2010. cited
by applicant .
3GPP TS 36.212 V9.2.0, Evolved Universal Terrestrial Radio Access
(E-UTRA) Multiplexing and Channel Coding, (Release 9), Jun. 2010.
cited by applicant .
3GPP TS 36.211 V9.0.0, Evolved Universal Terrestrial Radio Access
(E-UTRA) Physical Channels and Modulation, (Release 9), Dec. 2012.
cited by applicant .
3GPP TS 36.300 V8.5.0, Evolved Universal Terrestrial Radio Access
(E-UTRA) and Evolved Universal Terrestrial Radio Access Network
(E-UTRAN), (Release 8), May 2008. cited by applicant .
3GPP TS 36.331 V9.1.0, Evolved Universal Terrestrial Radio Access
(E-UTRA) Radio Resource Control (RRC), Protocol Specification,
(Release 9), Dec. 2009. cited by applicant.
|
Primary Examiner: Phan; Man
Attorney, Agent or Firm: Austin Rapp & Hardman
Claims
What is claimed is:
1. A method for receiving uplink control information (UCI),
comprising: receiving a first channel state information (CSI)
report for a CSI reference resource from a user equipment (UE) if
triggered; and receiving a second CSI report for the CSI reference
resource from the UE if triggered, wherein the second CSI report is
computed from a channel measurement based on only a non-zero power
CSI reference signal only on a single subframe within a configured
CSI reference signal resource associated with a CSI process,
wherein the first CSI report is computed from a channel measurement
based on only non-zero power CSI reference signals within a
configured CSI reference signal resource associated with a CSI
process based on an unrestricted observation interval in time and
frequency, wherein the single subframe is a subframe of the CSI
reference resource, and the CSI reference resource for the second
CSI report reported in uplink subframe n is defined by a valid
downlink subframe n-k.
2. The method of claim 1, wherein the valid downlink subframe is in
a set of subframes for a channel measurement for the Type 2 CSI
report.
3. The method of claim 1, wherein the valid downlink subframe is in
a set of subframes in which the non-zero power CSI reference signal
is configured.
4. The method of claim 1, wherein the valid downlink subframe is in
a set of subframes for Type 2 channel measurement if the set of
subframes for Type 2 channel measurement is configured, and wherein
the valid downlink subframe is in a set of subframes in which the
non-zero power CSI reference signal is configured if the set of
subframes for Type 2 channel measurement is not configured.
5. The method of claim 1, wherein the Type 2 CSI report is a
periodic CSI report.
6. The method of claim 5, wherein Type 2 CSI reporting is
configured in a CSI process configuration.
7. The method of claim 1, wherein the Type 2 CSI report is an
aperiodic CSI report.
8. The method of claim 7, wherein a field in a downlink control
information (DCI) specifies whether Type 2 aperiodic CSI reporting
is triggered.
9. The method of claim 1, wherein the Type 2 CSI report corresponds
to a configured CSI process.
10. A method for reporting uplink control information (UCI),
comprising: transmitting a first channel state information (CSI)
report for a CSI reference resource from a user equipment (UE) if
triggered; and transmitting a second CSI report for the CSI
reference resource if triggered, wherein the second CSI report is
computed from a channel measurement based on only a non-zero power
CSI reference signal only on a single subframe within a configured
CSI reference signal resource associated with a CSI process,
wherein the first CSI report is computed from a channel measurement
based on only non-zero power CSI reference signals within a
configured CSI reference signal resource associated with a CSI
process based on an unrestricted observation interval in time and
frequency, wherein the single subframe is a subframe of the CSI
reference resource, and the CSI reference resource for the second
CSI report reported in uplink subframe n is defined by a valid
downlink subframe n-k.
11. The method of claim 10, wherein the valid downlink subframe is
in a set of subframes for a channel measurement for the Type 2 CSI
report.
12. The method of claim 10, wherein the valid downlink subframe is
in a set of subframes in which the non-zero power CSI reference
signal is configured.
13. The method of claim 10, wherein the valid downlink subframe is
in a set of subframes for Type 2 channel measurement if the set of
subframes for Type 2 channel measurement is configured, and wherein
the valid downlink subframe is in a set of subframes in which the
non-zero power CSI reference signal is configured if the set of
subframes for Type 2 channel measurement is not configured.
14. The method of claim 10, wherein the Type 2 CSI report is a
periodic CSI report.
15. The method of claim 14, wherein Type 2 CSI reporting is
configured in a CSI process configuration.
16. The method of claim 10, wherein the Type 2 CSI report is an
aperiodic CSI report.
17. The method of claim 16, wherein a field in a downlink control
information (DCI) specifies whether Type 2 aperiodic CSI reporting
is triggered.
18. The method of claim 10, wherein the Type 2 CSI report
corresponds to a configured CSI process.
19. A base station configured for receiving uplink control
information (UCI), comprising: a processor; memory in electronic
communication with the processor; and instructions stored in the
memory, the instructions being executable to: receive a first
channel state information (CSI) report for a CSI reference resource
from a user equipment (UE) if triggered; and receive a second CSI
report for the CSI reference resource from the UE if triggered,
wherein the second CSI report is computed from a channel
measurement based on only a non-zero power CSI reference signal
only on a single subframe within a configured CSI reference signal
resource associated with a CSI process, wherein the first CSI
report is computed from a channel measurement based on only
non-zero power CSI reference signals within a configured CSI
reference signal resource associated with a CSI process based on an
unrestricted observation interval in time and frequency, wherein
the single subframe is a subframe of the CSI reference resource,
and the CSI reference resource for the second CSI report reported
in uplink subframe n is defined by a valid downlink subframe
n-k.
20. The base station of claim 19, wherein the valid downlink
subframe is in a set of subframes for a channel measurement for the
Type 2 CSI report.
21. The base station of claim 19, wherein the valid downlink
subframe is in a set of subframes in which the non-zero power CSI
reference signal is configured.
22. The base station of claim 19, wherein the valid downlink
subframe is in a set of subframes for Type 2 channel measurement if
the set of subframes for Type 2 channel measurement is configured,
and wherein the valid downlink subframe is in a set of subframes in
which the non-zero power CSI reference signal is configured if the
set of subframes for Type 2 channel measurement is not
configured.
23. The base station of claim 19, wherein the Type 2 CSI report is
a periodic CSI report.
24. The base station of claim 23, wherein Type 2 CSI reporting is
configured in a CSI process configuration.
25. The base station of claim 19, wherein the Type 2 CSI report is
an aperiodic CSI report.
26. The base station of claim 25, wherein a field in a downlink
control information (DCI) specifies whether Type 2 aperiodic CSI
reporting is triggered.
27. The base station of claim 23, wherein the Type 2 CSI report
corresponds to a configured CSI process.
28. A user equipment (UE) configured for reporting uplink control
information (UCI), comprising: a processor; memory in electronic
communication with the processor; and instructions stored in the
memory, the instructions being executable to: transmit a first
channel state information (CSI) report for a CSI reference resource
from a user equipment (UE) if triggered; and transmit a second CSI
report for the CSI reference resource if triggered, wherein the
second CSI report is computed from a channel measurement based on
only a non-zero power CSI reference signal only on a single
subframe within a configured CSI reference signal resource
associated with a CSI process, wherein the first CSI report is
computed from a channel measurement based on only non-zero power
CSI reference signals within a configured CSI reference signal
resource associated with a CSI process based on an unrestricted
observation interval in time and frequency, wherein the single
subframe is a subframe of the CSI reference resource, and the CSI
reference resource for the second CSI report reported in uplink
subframe n is defined by a valid downlink subframe n-k.
29. The UE of claim 28, wherein the valid downlink subframe is in a
set of subframes for a channel measurement for the Type 2 CSI
report.
30. The UE of claim 28, wherein the valid downlink subframe is in a
set of subframes in which the non-zero power CSI reference signal
is configured.
31. The UE of claim 28, wherein the valid downlink subframe is in a
set of subframes for Type 2 channel measurement if the set of
subframes for Type 2 channel measurement is configured, and wherein
the valid downlink subframe is in a set of subframes in which the
non-zero power CSI reference signal is configured if the set of
subframes for Type 2 channel measurement is not configured.
32. The UE of claim 28, wherein the Type 2 CSI report is a periodic
CSI report.
33. The UE of claim 32, wherein Type 2 CSI reporting is configured
in a CSI process configuration.
34. The UE of claim 28, wherein the Type 2 CSI report is an
aperiodic CSI report.
35. The UE of claim 34, wherein a field in a downlink control
information (DCI) specifies whether Type 2 aperiodic CSI reporting
is triggered.
36. The UE of claim 28, wherein the Type 2 CSI report corresponds
to a configured CSI process.
37. The UE of claim 1, wherein a downlink subframe is determined to
be valid based, in part, on whether it is a multimedia
broadcast/multicast service single-frequency network (MBSFN) frame.
Description
TECHNICAL FIELD
The present invention relates generally to wireless communications
and wireless communications-related technology. More specifically,
the present invention relates to systems and methods for channel
state measurement and reporting.
BACKGROUND
Wireless communication devices have become smaller and more
powerful in order to meet consumer needs and to improve portability
and convenience. Consumers have become dependent upon wireless
communication devices and have come to expect reliable service,
expanded areas of coverage and increased functionality. A wireless
communication system may provide communication for a number of
cells, each of which may be serviced by a base station. A base
station may be a fixed station that communicates with mobile
stations.
Various signal processing techniques may be used in wireless
communication systems to improve efficiency and quality of wireless
communication. Benefits may be realized by improved methods for
reporting uplink control information (UCI) by a wireless
communication device.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating a wireless communication
system that utilizes Type 2 CSI reporting;
FIG. 2 is a flow diagram of a method for Type 2
measurement/reporting;
FIG. 3 is a flow diagram of another method for Type 2
measurement/reporting;
FIG. 4 is a block diagram illustrating the layers used by a user
equipment (UE);
FIG. 5 illustrates the slot and subframe structure for Frame
Structure Type 2;
FIG. 6 illustrates the procedures for determining the CSI reference
resources for periodic Type 2 CSI measurement/reporting;
FIG. 7 illustrates the procedures for determining the CSI reference
resources for aperiodic Type 2 CSI measurement/reporting;
FIG. 8 illustrates various components that may be utilized in a
user equipment (UE); and
FIG. 9 illustrates various components that may be utilized in an
eNB.
DETAILED DESCRIPTION
A method for receiving uplink control information (UCI) is
described. A Type 2 channel state information (CSI) report for a
CSI reference resource is received from a user equipment (UE). The
Type 2 CSI report is computed from a channel measurement based on a
non-zero power reference signal on a single subframe within a
configured CSI-RS resource associated with a CSI process.
The single subframe may be a subframe of the CSI reference
resource. The CSI reference resource for the Type 2 CSI report
reported in uplink subframe n may be defined by a valid downlink
subframe n-nCQI_ref. The valid downlink subframe may be in a set of
subframes for a channel measurement for the Type 2 CSI report. The
valid downlink subframe may be in a set of subframes in which the
non-zero power reference signal is configured.
The valid downlink subframe may be in a set of subframes for Type 2
channel measurement if the set of subframes for Type 2 channel
measurement is configured. The valid downlink subframe may be in a
set of subframes in which the non-zero power reference signal is
configured if the set of subframes for Type 2 channel measurement
is not configured. The Type 2 CSI report may be a periodic CSI
report. Type 2 CSI reporting may be configured in a CSI process
configuration. The Type 2 CSI report may also be an aperiodic CSI
report. A field in a downlink control information (DCI) may specify
whether Type 2 aperiodic CSI reporting is triggered. The Type 2 CSI
report may correspond to a configured CSI process.
A method for reporting uplink control information (UCI) is also
described. A Type 2 channel state information (CSI) report for a
CSI reference resource is generated. The Type 2 CSI report is sent
to a base station. The Type 2 CSI report is computed from a channel
measurement based on a non-zero power reference signal on a single
subframe within a configured CSI-RS resource associated with a CSI
process.
A base station configured for receiving uplink control information
(UCI) is described. The base station includes a processor, memory
in electronic communication with the processor and instructions
stored in the memory. The instructions are executable to receive a
Type 2 channel state information (CSI) report for a CSI reference
resource from a user equipment (UE). The Type 2 CSI report is
computed from a channel measurement based on a non-zero power
reference signal on a single subframe within a configured CSI-RS
resource associated with a CSI process.
A user equipment (UE) configured for reporting uplink control
information (UCI) is also described. The UE includes a processor,
memory in electronic communication with the processor and
instructions stored in the memory. The instructions are executable
to generate a Type 2 channel state information (CSI) report for a
CSI reference resource. The instructions are also executable to
send the Type 2 CSI report to a base station. The Type 2 CSI report
is computed from a channel measurement based on a non-zero power
reference signal on a single subframe within a configured CSI-RS
resource associated with a CSI process.
The 3rd Generation Partnership Project, also referred to as "3GPP,"
is a collaboration agreement that aims to define globally
applicable technical specifications and technical reports for third
and fourth generation wireless communication systems. The 3GPP may
define specifications for the next generation mobile networks,
systems and devices.
3GPP Long Term Evolution (LTE) is the name given to a project to
improve the Universal Mobile Telecommunications System (UMTS)
mobile phone or device standard to cope with future requirements.
In one aspect, UMTS has been modified to provide support and
specification for the Evolved Universal Terrestrial Radio Access
(E-UTRA) and Evolved Universal Terrestrial Radio Access Network
(E-UTRAN).
At least some aspects of the systems and methods disclosed herein
may be described in relation to the 3GPP LTE and LTE-Advanced
standards (e.g., Release-8, Release-9, Release-10 and Release-11).
However, the scope of the present disclosure should not be limited
in this regard. At least some aspects of the systems and methods
disclosed herein may be utilized in other types of wireless
communication systems.
The term "simultaneous" may be used herein to denote a situation
where two or more events occur in overlapping time frames. In other
words, two "simultaneous" events may overlap in time to some
extent, but are not necessarily of the same duration. Furthermore,
simultaneous events may or may not begin or end at the same
time.
FIG. 1 is a block diagram illustrating a wireless communication
system 100 that utilizes Type 2 CSI reporting. Downlink and uplink
transmissions are organized into radio frames. Two radio frame
structures are supported: Type 1 (applicable to frequency division
duplex (FDD)) and Type 2 (applicable to time division duplex
(TDD)). Type 2 CSI reporting is defined as channel measurements for
a CSI report that are based on only either or both of a channel
measurement in a single subframe and an interference measurement in
a single subframe. The details describing Type 2 CSI reporting are
given below. In contrast, Type 1 CSI reporting is defined as
channel measurements for a CSI report that are based on
unrestricted observations or measurements in time and/or frequency.
Thus, Type 1 CSI reporting may provide a CSI report that includes
channel measurements for the reference signal over multiple
contiguous or non-contiguous subframes.
It is possible that some of the subframes measured for Type 1 CSI
reporting may not carry a reference signal. If a UE 104 measures
the channel in multiple subframes, some of which do not carry a
reference signal, and then includes both measurements in generating
a report (such as a weighted average of measurements), the
generated report may include erroneous measurements. Thus, there is
a need for Type 2 CSI reporting to provide more accurate and
reliable CSI reports to an eNB 102. Even though a UE may not know
whether a subframe is an uplink, downlink or special subframe, the
resulting report may be useful to the eNB, because the eNB is aware
of whether a CSI report is generated based on a measurement on a
downlink subframe, an uplink subframe or a special subframe.
An eNB 102 may be in wireless communication with one or more user
equipments (UEs) 104. An eNB 102 may also be referred to as an
access point, a Node B, an evolved Node B, a base station or some
other terminology. Likewise, a user equipment (UE) 104 may also be
referred to as a mobile station, a subscriber station, an access
terminal, a remote station, a user terminal, a terminal, a handset,
a subscriber unit, a wireless communication device, or some other
terminology.
Communication between a user equipment (UE) 104 and an eNB 102 may
be accomplished using transmissions over a wireless link, including
an uplink and a downlink. The uplink refers to communications sent
from a user equipment (UE) 104 to an eNB 102. The downlink refers
to communications sent from an eNB 102 to a user equipment (UE)
104. The communication link may be established using a single-input
and single-output (SISO), multiple-input and single-output (MISO),
single-input and multiple-output (SIMO) or a multiple-input and
multiple-output (MIMO) system. A MIMO system may include both a
transmitter and a receiver equipped with multiple transmit and
receive antennas. Thus, an eNB 102 may have multiple antennas
110a-n and a user equipment (UE) 104 may have multiple antennas
112a-n. In this way, the eNB 102 and the user equipment (UE) 104
may each operate as either a transmitter or a receiver in a MIMO
system. One benefit of a MIMO system is improved performance if the
additional dimensionalities created by the multiple transmit and
receive antennas are utilized.
The user equipment (UE) 104 communicates with an eNB 102 using one
or more antenna ports, which may be realized by one or more
physical antennas 112a-n. The user equipment (UE) 104 may include a
transceiver 132, a decoder 124, an encoder 128 and an operations
module 116. The transceiver 132 may include a receiver 133 and a
transmitter 135. The receiver 133 may receive signals from the eNB
102 using one or more antennas 112a-n. For example, the receiver
133 may receive and demodulate received signals using a demodulator
134. The transmitter 135 may transmit signals to the eNB 102 using
one or more antenna ports, which may be realized by one or more
physical antennas 112a-n. For example, the transmitter 135 may
modulate signals using a modulator 136 and transmit the modulated
signals.
The receiver 133 may provide a demodulated signal to the decoder
124. The user equipment (UE) 104 may use the decoder 124 to decode
signals and make downlink decoding results 126. The downlink
decoding results 126 may indicate whether data was received
correctly. For example, the downlink decoding results 126 may
indicate whether a packet was correctly or erroneously received
(i.e., positive acknowledgement, negative acknowledgement or
discontinuous transmission (no signal)).
The operations module 116 may be a software and/or hardware module
used to control user equipment (UE) 104 communications. For
example, the operations module 116 may determine when the user
equipment (UE) 104 requires resources to communicate with an eNB
102.
In 3.sup.rd Generation Partnership Project (3GPP) Long Term
Evolution (LTE)-Advanced, additional control feedback will have to
be sent on control channels to accommodate MIMO and carrier
aggregation. Carrier aggregation refers to transmitting data on
multiple component carriers (CCs) (or cells) that are contiguously
or separately located. In carrier aggregation (CA), only one uplink
component carrier (CC) (or cell) (i.e., PCC or PCell) may be
utilized for transmission using the physical uplink control channel
(PUCCH). A component carrier (CC) is a carrier frequency to which
cells belong.
To select a suitable modulation scheme and channel coding rate, the
transmitter needs information about the radio-link between the
transmitter and the receiver (i.e., channel state information
(CSI)). The CSI may also be used for channel-dependent scheduling.
In an FDD system, only the receiver can accurately and reliably
estimate the radio-link channel condition. For downlink
transmissions, the base station (e.g., an eNode B, eNB 102,
transmission point) sends a signal to the UE 104 that includes time
and frequency resources as well as sequence information, antenna
port information and transmit power. In release 11 of the 3GPP
specification, one reference signal that is used for channel
measurement is the CSI-RS.
The user equipment (UE) 104 may transmit uplink control information
(UCI) to an eNB 102 on the uplink. The uplink control information
(UCI) may include one or more channel state information (CSI)
reports. A CSI report may be a Type 1 CSI report 120 or a Type 2
CSI report 122. A channel state information (CSI) report may
include a channel quality indicator (CQI), a precoder matrix
indicator (PMI), and/or a rank indicator (RI). The rank indicator
(RI) provides a recommendation on the number of spatial layers that
should preferably be used for downlink transmission. The precoder
matrix indicator (PMI) indicates the precoder matrix that should be
used for downlink transmission. The precoder matrix may be
determined by considering the number of supported layers indicated
in the rank indicator (RI). The CQI indicates the highest
modulation and coding scheme (MCS) that can be used for
transmission of the PDSCH with a block error rate no larger than
10%.
A CSI report may be transmitted to an eNB 102 using aperiodic
reporting and/or periodic reporting. Aperiodic CSI reports are sent
by a UE 104 when explicitly requested (by a field in an uplink DCI
(downlink control information)). Periodic CSI reports are
configured by the eNB 102 (which may also be referred to as the
network) to be sent by the UE 104 periodically.
The CQI indices and their interpretations are given in Table 1
below.
TABLE-US-00001 TABLE 1 CQI Code rate .times. index Modulation 1024
Efficiency 0 out of range 1 QPSK 78 0.1523 2 QPSK 120 0.2344 3 QPSK
193 0.3770 4 QPSK 308 0.6016 5 QPSK 449 0.8770 6 QPSK 602 1.1758 7
16 QAM 378 1.4766 8 16 QAM 490 1.9141 9 16 QAM 616 2.4063 10 64 QAM
466 2.7305 11 64 QAM 567 3.3223 12 64 QAM 666 3.9023 13 64 QAM 772
4.5234 14 64 QAM 873 5.1152 15 64 QAM 948 5.5547
Based on an unrestricted observation interval in time and
frequency, the UE 104 may be required to derive, for each CQI value
reported in uplink subframe n, the highest CQI index between 1 and
15 which satisfies the condition that a single physical downlink
shared channel (PDSCH) transport block with a combination of
modulation scheme and transport block size corresponding to the CQI
index and occupying a group of downlink physical resource blocks
(termed the CSI reference resource) could be received with a
transport block error probability not exceeding 0.1. If CQI index 1
does not satisfy this condition, the UE 104 may instead use CQI
index 0.
A UE 104 in transmission mode 10 can be configured with one or more
CSI processes per serving cell by higher layers 114. Each CSI
process may be associated with a CSI-RS resource and a CSI
interference measurement (CSI-IM) resource. A CSI reported by the
UE 104 corresponds to a CSI process configured by higher layers
114.
In the frequency domain, the CSI reference resource is defined by
the group of downlink physical resource blocks corresponding to the
band to which the CQI value relates. In the time domain, for a UE
104 configured in transmission mode 1-9 or in transmission mode 10
with a single configured CSI process for the serving cell, the CSI
reference resource is defined by a single downlink subframe
n-n.sub.CQI.sub.--.sub.ref. For periodic CSI reporting,
n.sub.CQI.sub.--.sub.ref is the smallest value greater than or
equal to 4 such that subframe n-n.sub.CQI.sub.--.sub.ref
corresponds to a valid downlink subframe. For aperiodic CSI
reporting, n.sub.CQI.sub.--.sub.ref is such that the reference
resource is in the same valid downlink subframe as the
corresponding CSI request in an uplink DCI format. For aperiodic
CSI reporting, n.sub.CQI.sub.--.sub.ref is equal to 4 and the
downlink subframe n-n.sub.CQI.sub.--.sub.ref corresponds to a valid
downlink subframe, where the downlink subframe
n-n.sub.CQI.sub.--.sub.ref is received after the subframe with the
corresponding CSI request in a random access response grant.
For a UE 104 configured in transmission mode 10 with multiple
configured CSI processes for the serving cell, the CSI reference
resource for a given CSI process may be defined by a single
downlink subframe n-n.sub.CQI.sub.--.sub.ref. For FDD and periodic
or aperiodic CSI reporting, n.sub.CQI.sub.--.sub.ref is the
smallest value greater than or equal to 5 such that the downlink
subframe n-n.sub.CQI.sub.--.sub.ref corresponds to a valid downlink
subframe. For FDD and aperiodic CSI reporting,
n.sub.CQI.sub.--.sub.ref is equal to 5 and the downlink subframe
n-n.sub.CQI.sub.--.sub.ref corresponds to a valid downlink
subframe, where the downlink subframe n-n.sub.CQI.sub.--.sub.ref is
received after the subframe with the corresponding CSI request in a
random access response grant.
For TDD with two or three configured CSI processes and aperiodic or
periodic CSI reporting, n.sub.CQI.sub.--.sub.ref is the smallest
value greater than or equal to 4 such that the downlink subframe
n-n.sub.CQI.sub.--.sub.ref corresponds to a valid downlink
subframe. For TDD with two or three configured CSI processes and
aperiodic reporting, n.sub.CQI.sub.--.sub.ref is equal to 4 and the
downlink subframe n-n.sub.CQI.sub.--.sub.ref corresponds to a valid
downlink subframe, where the downlink subframe
n-n.sub.CQI.sub.--.sub.ref is received after the subframe with the
corresponding CSI request in a random access response grant.
For TDD with four configured CSI processes and periodic or
aperiodic CSI reporting, n.sub.CQI.sub.--.sub.ref is the smallest
value greater than or equal to 4 such that the downlink subframe
n-n.sub.CQI.sub.--.sub.ref corresponds to a valid downlink
subframe. For TDD with four configured CSI processes and aperiodic
CSI reporting, n.sub.CQI.sub.--.sub.ref is equal to 5 and the
downlink subframe n-n.sub.CQI.sub.--.sub.ref corresponds to a valid
downlink subframe, where the downlink subframe
n-n.sub.CQI.sub.--.sub.ref is received after the subframe with the
corresponding CSI request in a random access response grant.
Upon decoding in subframe n either an uplink DCI (downlink control
information) or a random access response grant, the UE 104 may
perform aperiodic CSI reporting using the physical uplink shared
channel (PUSCH) in subframe n+k on a serving cell, if the
respective CSI request field is set to trigger a report and is not
reserved. If the CSI request field is 1 bit, the CSI request field
is set to 1 and the UE 104 is configured in transmission mode 1-9,
a report is triggered for the serving cell. If the CSI request
field is 1 bit and the UE 104 is configured in transmission mode
10, a report is triggered for a set of CSI process(es) for the
serving cell corresponding to the higher layer 114 configured set
of CSI process(es) associated with the value of the CSI request
field in Table 1 below.
TABLE-US-00002 TABLE 2 Value of CSI request field Description `00`
No aperiodic CSI report is triggered `01` Aperiodic CSI report is
triggered for serving cell `10` Aperiodic CSI report is triggered
for a 1.sup.st set of serving cells configured by higher layers
`11` Aperiodic CSI report is triggered for a 2.sup.nd set of
serving cells configured by higher layers
If the CSI request field size is 2 bits and the UE 104 is
configured in transmission mode 1-9 for all serving cells, a report
is triggered according to the value in Table 2 above corresponding
to aperiodic CSI reporting. If the CSI request field size is 2 bits
and the UE 104 is configured in transmission mode 10 for at least
one serving cell, a report is triggered according to the value in
Table 3 below corresponding to aperiodic CSI reporting. For a given
serving cell, if the UE 104 is configured in transmission modes
1-9, the "CSI process" in Table 3 refers to the aperiodic CSI
configured for the UE 104 on the given serving cell. A UE 104 is
not expected to be configured by higher layers 114 with more than 5
CSI processes in each of the 1.sup.st and 2.sup.nd set of CSI
process(es) in Table 3.
TABLE-US-00003 TABLE 3 Value of CSI request field Description `00`
No aperiodic CSI report is triggered `01` Aperiodic CSI report is
triggered for a set of CSI process(es) configured by higher layers
for serving cell `10` Aperiodic CSI report is triggered for a
1.sup.st set of CSI process(es) configured by higher layers `11`
Aperiodic CSI report is triggered for a 2.sup.nd set of CSI
process(es) configured by higher layers
When the CSI request field from an uplink DCI format is set to
trigger a report, for FDD k=4, and for TDD UL/DL configuration 1-6,
k is given from Table 4 below. TDD UL/DL configuration is a
configuration that indicates whether a subframe is uplink, downlink
or a special subframe. For TDD UL/DL configuration 0, if the most
significant bit (MSB) of the uplink index is set to 1 and the least
significant bit (LSB) of the uplink index is set to 0, k is given
in Table 5 below.
TABLE-US-00004 TABLE 4 TDD UL/DL subframe number n Configuration 0
1 2 3 4 5 6 7 8 9 0 4 6 4 6 1 6 4 6 4 2 4 4 3 4 4 4 4 4 4 5 4 6 7 7
7 7 5
TABLE-US-00005 TABLE 5 TDD UL/DL subframe number n Configuration 0
1 2 3 4 5 6 7 8 9 0 9 6 9 6 1 2 3 2 3 6 5 5 6 6 8
If the most significant bit (MSB) of the uplink index is set to 0
and the least significant bit (LSB) of the uplink index is set to
1, k is equal to 7. If both the most significant bit (MSB) and the
least significant bit (LSB) of the uplink index are set to 1, k is
given in Table 4. For TDD, if a UE 104 is configured with more than
one serving cell and if the UL/DL configurations of at least two
serving cells are different, the TDD UL/DL Configuration given in
Table 4 refers to the UL-reference UL/DL configuration.
When the CSI request field from a Random Access Response Grant is
set to trigger a report and is not reserved, k is equal to k.sub.1
if the uplink delay field is set to zero. The UE 104 may postpone
aperiodic CSI reporting to the next available uplink subframe if
the UL delay field is set to 1.
A UE 104 may be semi-statically configured by higher layers 114 to
periodically feedback different CSI components (CQI, PMI, PTI,
and/or RI) on the physical uplink control channel (PUCCH). A UE 104
in transmission mode 10 can be configured by higher layers 114 for
multiple periodic CSI reports corresponding to one or more CSI
processes per serving cell on the PUCCH.
The information element CQI-ReportConfig given below is used to
specify the CQI reporting configuration.
TABLE-US-00006 CQI-ReportConfig Information Element
CQI-ReportConfig-r10 ::=SEQUENCE { cqi-ReportAperiodic-r10
CQI-ReportAperiodic-r10 OPTIONAL, - - Need ON
nomPDSCH-RS-EPRE-Offset INTEGER (-1..6), cqi-ReportPeriodic-r10
CQI-ReportPeriodic-r10 OPTIONAL, - - Need ON pmi-RI-Report-r9
ENUMERATED {setup} OPTIONAL, - - Cond PMIRIPCell
csi-SubframePatternConfig-r10 CHOICE { release NULL, setup SEQUENCE
{ csi-MeasSubframeSet1-r10 MeasSubframePattern-r10,
csi-MeasSubframeSet2-r10 MeasSubframePattern-r10 } } OPTIONAL --
Need ON }
The "MeasSubframePattern-r10" is a bit map of size 20, 40, 60, or
70 bits. Each bit in the bit map represents a subframe. The value
of each bit determines whether that subframe belongs to the
measurement set or not. For example, 1 may indicate inclusion and 0
may indicate exclusion.
The uplink control information (UCI) (such as a CSI report) may be
generated by an uplink control information (UCI) reporting module
118 and transferred to an encoder 128. The encoder 128 may then
provide the uplink control information (UCI) to the transmitter
135.
The time and frequency resources may be quantized to create a grid
known as the time-frequency grid. In the time domain, 10
milliseconds (ms) is referred to as one radio frame. One radio
frame may include 10 subframes, each with a duration of 1 ms, which
is the duration of transmission in the uplink and/or downlink.
Every subframe may be divided into two slots, each with a duration
of 0.5 ms. Each slot may be divided into 7 symbols. The frequency
domain may be divided into bands with a 15 kilohertz (kHz) width,
referred to as a subcarrier. One resource element has a duration of
one symbol in the time domain and the bandwidth of one subcarrier
in the frequency domain.
The minimum amount of resource that can be allocated for the
transmission of information in the uplink or downlink in any given
subframe is two resource blocks (RBs), with one RB at each slot.
One RB has a duration of 0.5 ms (7 symbols or one slot) in the time
domain and a bandwidth of 12 subcarriers (180 kHz) in the frequency
domain. At any given subframe, a maximum of two RBs (one RB at each
slot) can be used by a given user equipment (UE) 104 for the
transmission of uplink control information (UCI) in the physical
uplink control channel (PUCCH).
In LTE Release-8, only one uplink component carrier (CC) 106 or
serving cell 107 and one downlink component carrier (CC) 108 or
serving cell 107 can be used for transmission to and reception from
each user equipment (UE) 104.
In 3GPP Long Term Evolution (LTE) Release-10 (LTE-A or Advanced
EUTRAN), carrier aggregation was introduced. Carrier aggregation
may also be referred to as cell aggregation. Carrier aggregation is
supported in both the uplink and the downlink with up to five
component carriers (CCs) 106, 108. Each component carrier (CC) 106,
108 or cell 107 may have a transmission bandwidth of up to 110
resource blocks (i.e., up to 20 megahertz (MHz)). In carrier
aggregation, two or more component carriers (CCs) 106, 108 are
aggregated to support wider transmission bandwidths up to one
hundred megahertz (MHz). A user equipment (UE) 104 may
simultaneously receive and/or transmit on one or multiple component
carriers (CCs) 106, 108, depending on the capabilities of the user
equipment (UE) 104.
A user equipment (UE) 104 may communicate with an eNB 102 using
multiple component carriers (CCs) 108 at the same time. For
example, a user equipment (UE) 104 may communicate with an eNB 102
using a primary cell (PCell) 107a while simultaneously
communicating with the eNB 102 using secondary cell(s) (SCell)
107b. Similarly, an eNB 102 may communicate with a user equipment
(UE) 104 using multiple component carriers (CCs) 108 at the same
time. For example, an eNB 102 may communicate with a user equipment
(UE) 104 using a primary cell (PCell) 107a while simultaneously
communicating with the user equipment (UE) 104 using secondary
cell(s) (SCell) 107b.
An eNB 102 may include a transceiver 137 that includes a receiver
138 and a transmitter 140. An eNB 102 may additionally include a
decoder 142, an encoder 144 and an operations module 146. An eNB
102 may receive uplink control information (UCI) 121 using its one
or more antenna ports, which may be realized by one or more
physical antennas 110a-n, and its receiver 138. The receiver 138
may use the demodulator 139 to demodulate the uplink control
information (UCI) 121.
The decoder 142 may include an uplink control information (UCI)
receiving module 143. An eNB 102 may use the uplink control
information (UCI) receiving module 143 to decode and interpret the
uplink control information (UCI) 121 received by the eNB 102. The
eNB 102 may use the decoded uplink control information (UCI) 121 to
perform certain operations, such as retransmit one or more packets
based on scheduled communication resources for the user equipment
(UE) 104.
The operations module 146 may include a retransmission module 147
and a scheduling module 148. The retransmission module 147 may
determine which packets to retransmit (if any) based on the uplink
control information (UCI) 121. The scheduling module 148 may be
used by the eNB 102 to schedule communication resources (e.g.,
bandwidth, time slots, frequency channels, spatial channels, etc.).
The scheduling module 148 may use the uplink control information
(UCI) 121 to determine whether (and when) to schedule communication
resources for the user equipment (UE) 104.
The operations module 146 may provide data 145 to the encoder 144.
For example, the data 145 may include packets for retransmission
and/or a scheduling grant for the user equipment (UE) 104. The
encoder 144 may encode the data 145, which may then be provided to
the transmitter 140. The transmitter 140 may modulate the encoded
data using the modulator 141. The transmitter 140 may transmit the
modulated data to the user equipment (UE) 104 using one or more
antenna ports, which may be realized by the one or more physical
antennas 110a-n.
When carrier aggregation is configured, a user equipment (UE) 104
may have only one radio resource control (RRC) connection with the
network. At the radio resource control (RRC) connection
establishment/re-establishment/handover, one serving cell 107
(i.e., the primary cell (PCell) 107a) provides the non-access
stratum (NAS) mobility information (e.g., Tracking Area Identity
(TAI)) and the security input.
In the downlink, the component carrier (CC) 108 corresponding to
the primary cell (PCell) 107a is the downlink primary component
carrier (DL PCC) 108a. In the uplink, the component carrier (CC)
106 corresponding to the primary cell (PCell) 107a is the uplink
primary component carrier (UL PCC) 106a. Depending on the
capabilities of the user equipment (UE) 104, one or more secondary
component carriers (SCC) 106b, 108b or secondary cells (SCell) 107b
may be configured to form a set of serving cells with the primary
cell (PCell) 107a. In the downlink, the component carrier (CC) 108
corresponding to the secondary cell (SCell) 107b is the downlink
secondary component carrier (DL SCC) 108b. In the uplink, the
component carrier (CC) 106 corresponding to the secondary cell
(SCell) 107b is the uplink secondary component carrier (UL SCC)
106b. The number of downlink component carriers (CCs) 108 may be
different from the number of uplink component carriers (CCs) 106
because multiple cells may share one uplink component carrier (CC)
106.
If carrier aggregation is configured, a user equipment (UE) 104 may
have multiple serving cells: a primary cell (PCell) 107a and one or
more secondary cells (SCell) 107b. From a network perspective, a
serving cell 107 may be used as the primary cell (PCell) 107a by
one user equipment (UE) 104 and used as a secondary cell (SCell)
107b by another user equipment (UE) 104. If carrier aggregation is
not configured, a primary cell (PCell) 107a operates a single
serving cell. There may be one or more secondary cells (SCell) 107b
in addition to the primary cell (PCell) 107a if carrier aggregation
is configured. One benefit of using carrier aggregation is that
additional downlink and/or uplink data may be transmitted. As a
result of the additional downlink data, additional uplink control
information (UCI) may be needed.
A UE 104 is in RRC_CONNECTED state when an RRC (radio resource
control) connection has been established. If no RRC connection has
been established, the UE 104 is in RRC_IDLE state.
A number of spatial channels may be available on each serving cell
107 by using multiple antenna ports at a transmitter and a
receiver. Therefore, multiple codewords (up to two codewords) may
be transmitted simultaneously.
A channel state information (CSI) report may be used to inform the
eNB 102 to adjust the transmission rate (modulation scheme and
coding rate) dynamically based on the existing channel conditions
at the user equipment (UE) 104. For example, if a channel state
information (CSI) report indicates a good channel quality at the
user equipment (UE) 104, the eNB 102 may select a higher order
modulation and coding rate, thereby achieving a higher transmission
rate for the downlink transmission of data on the physical downlink
shared channel (PDSCH). If a channel state information (CSI) report
indicates a poor channel quality at the user equipment (UE) 104,
the eNB 102 may select a lower order modulation and coding rate,
thereby achieving higher reliability for the transmission.
In Type 1 CSI measurement/reporting (the existing measurement used
in Release 11 of the 3GPP specification), a UE 104 in transmission
mode 10 may derive the channel measurements for computing the CQI
value reported in uplink subframe n (that corresponds to a CSI
process) based on only the non-zero power CSI-RS within a
configured CSI-RS resource associated with the CSI process.
However, it is possible that subframe n carries the CSI-RS in radio
frame k and does not carry the CSI-RS in radio frame k+m. If the UE
104 measures the channel in both subframes and includes both
measurements in generating a report (such as a weighted averaging
of measurements), then the generated report includes erroneous
measurements.
The use of Type 2 CSI measurement/reporting provides meaningful and
reliable reports to the eNB 102 regardless of whether the CSI-RS is
transmitted on the subframe corresponding to the CSI report.
Furthermore, since the eNB 102 schedules the transmission of the
CSI-RS, the eNB 102 is aware of whether the reported measurement is
a valid channel state measurement or simply an interference
measurement.
A UE 104 may be configured with multiple CSI processes. A UE 104 in
transmission mode 10 can be configured with one or more CSI
processes per serving cell by higher layers 114. Each CSI process
may be associated with a CSI-RS resource (including time and
frequency resources allocated for transmission of CSI-RS, a CSI-RS
sequence, an antenna port at which the CSI-RS is transmitted and
the transmit power of the CSI-RS) and with a CSI-interference
measurement (CSI-IM) resource (including the time and frequency
resources on which the UE should perform interference measurement).
Each CSI process is also associated with a reporting configuration
which includes configurations for periodic and aperiodic reporting
such as the CQI format (sub-band or wideband CQI), the resource
indices (S1 or S2), the periodicity of periodic reports, the
subframe offset associated with the periodic reports, etc. For
simplicity, only one CSI process is considered, with the configured
CSI resource and periodic and aperiodic CSI reporting
configurations.
In one configuration, the same CSI process may be used for both
Type 1 measurement/reporting and Type 2 measurement/reporting. The
measurement configuration may be semi-static, dynamic or periodic.
If the measurement configuration is semi-static, this enables Type
2 measurement/reporting in a CSI process. A set of subframes for
Type 2 channel measurement may also be configured.
If the measurement configuration is dynamic, triggering may be used
for Type 2 aperiodic CSI reporting. In this configuration, a field
(which may be one bit or two bits) in the uplink DCI (e.g., DCI
format 0 or DCI format 4) may specify whether Type 2 aperiodic
reporting is triggered.
Downlink control information may be sent in packets of
pre-specified length, known as DCI. The DCI may be carried by the
PDCCH or the enhanced physical downlink control channel (EPDCCH).
Das may carry different information. For example, one DCI may be
used to inform UEs 104 about downlink resource allocation and
another DCI may be used to inform a specific UE 104 about uplink
resource allocation. Depending on the functionality of a DCI,
different Das may have different lengths. Different Das may be
distinguished by the way they are formatted and coded, which is
referred to as the DCI format. A DCI may be used to transport
downlink or uplink scheduling information, requests for periodic
CQI reports, notifications of multicast control channel (MCCH)
changes or uplink power control commands for one cell and one Radio
Network Temporary Identifier (RNTI). The RNTI may be implicitly
encoded in the cyclic redundancy check (CRC).
An uplink DCI allocates resources for uplink transmission. An
uplink DCI may also be referred to as an uplink grant (e.g., DCI
format 0/4). A downlink DCI allocates resources for downlink
transmission. A downlink DCI may also be referred to as a downlink
grant (e.g., DCI format 1/1A/2/2A/2B/2C/2D).
A bit field in the DCI indicates which reports of a type (i.e.,
Type 1 and/or Type 2) should be included in the UCI. The bit field
may include multiple bits (e.g., 2 bits for a set of CSI reports
corresponding to one or more CSI processes, 1 bit for a type 2
trigger, etc.). If Type 1 aperiodic CSI reporting is triggered, the
UE 104 may be required to include a Type 1 CSI report 120 in the
UCI. If Type 2 aperiodic CSI reporting is triggered, the UE 104 may
be required to include a specified number of Type 2 CSI reports 122
(predefined or signaled by RRC) and a Type 1 CSI report 120 for
each CSI process within the set of CSI processes with corresponding
CSI reports include in the UCI.
If the measurement configuration is periodic, the UE 104 may
periodically generate and send CSI reports to the eNB 102. For Type
1 periodic CSI reporting, the periodicity and relative reporting
offset for the subframe set S1 and the periodicity and relative
reporting offset for the subframe set S2 are configured for each
CSI process. For Type 2 periodic CSI reporting, additional
periodicity and relative reporting offset is configured for each
CSI process.
In another configuration, two CSI processes are used for Type 1
measurement/reporting and Type 2 measurement/reporting. One CSI
process may be dedicated for Type 1 CSI reporting and another CSI
process may be dedicated for Type 2 CSI reporting. If the
measurement configuration is semi-static, a CSI process
configuration may include a configuration of either Type 1 CSI
reporting or Type 2 CSI reporting. Furthermore, a set of subframes
for Type 2 channel measurement may be configured.
The triggering for Type 2 aperiodic CSI reporting is included in a
DCI. A bit field in the DCI may indicate which CSI processes should
be included in the UCI. If a triggered CSI process is for Type 2
aperiodic CSI reporting, the UE 104 may be required to include X
numbers of Type 2 reports (X may be predefined or signaled by the
RRC).
For CSI processes for Type 1 periodic CSI reporting, the
periodicity and relative reporting offset for the subframe set 1
(S1) and the periodicity and relative reporting offset for subframe
set 2 (S2) are configured. For CSI processes for Type 2 periodic
CSI reporting, the periodicity and relative reporting offset is
configured.
FIG. 2 is a flow diagram of a method 200 for Type 2
measurement/reporting. The method 200 may be performed by a UE 104.
The UE 104 may receive 202 a non-zero reference signal on a
downlink channel. The UE 104 may measure 204 the downlink channel
for a single subframe. The UE 104 may then generate a Type 2 CSI
report 122 for a CSI reference resource based on the measured
downlink channel for the single subframe. The Type 2 CSI report 122
may be computed from a channel measurement based on a non-zero
reference signal on a single subframe within a configured CSI-RS
resource associated with a CSI process. The UE 104 may send 208 the
Type 2 CSI report to an eNB 102.
FIG. 3 is a flow diagram of another method 300 for Type 2
measurement/reporting. The method 300 may be performed by an eNB
102. The eNB 102 may transmit 302 a reference signal on a downlink
channel to a UE 104. The eNB 102 may receive 304 a Type 2 CSI
report 122 for a CSI reference resource from the UE 104. The Type 2
CSI report 122 may be computed from a channel measurement based on
a non-zero power reference signal on a single subframe within a
configured CSI-RS resource associated with a CSI process. The eNB
102 may schedule 306 resources based on the Type 2 CSI report 122
for a CSI reference resource.
FIG. 4 is a block diagram illustrating the layers realized by a
user equipment (UE) 404. The user equipment (UE) 404 of FIG. 4 may
be one configuration of the user equipment (UE) 104 of FIG. 1. The
user equipment (UE) 404 may include a radio resource control (RRC)
layer 450, a radio link control (RLC) layer 451, a medium access
control (MAC) layer 452 and a physical (PHY) layer 453. The RRC
layer 450, RLC layer 451 and MAC layer 452 may be referred to as
higher layers 118. Mainly the procedures described herein relate to
the PHY layer 453. As used herein, the phrase "configured by higher
layers" means that the PHY layer 453 is configured by the higher
layer. The user equipment (UE) 404 may include additional layers
not shown in FIG. 4.
FIG. 5 illustrates the slot and subframe structure for Frame
Structure Type 2. Frame Structure Type 2 may be applicable to TDD.
Each radio frame 554 of length T.sub.f=307200T.sub.s=10 ms,
includes two half-frames of length 153600T.sub.s=5 ms each. Each
half-frame includes five subframes 555 of length 30720T.sub.s=1 ms.
The Type 2 Frame Structure may be a downlink subframe 555, an
uplink subframe 555 or a special subframe 555. The special subframe
555 may be preceded by a downlink subframe 555 and succeeded by an
uplink subframe 555. The special subframe 555 may be divided into
three parts: DwPTS, GP and UpPTS. DwPTS is the downlink part of the
special subframe 555, GP is the guard period and UpPTS is the
uplink part of the special subframe 555.
FIG. 6 illustrates the procedures for determining the CSI reference
resources for periodic Type 2 CSI measurement/reporting. The
computation of PMI and RI of a CSI report may be linked to the
value of the CQI. Multiple radio frames 654 are illustrated. Each
radio frame includes 654 ten subframes 655, numbered from 0 to 9.
The radio frame number may also be referred to as the System Frame
Number (SFN).
In Release 10 and 11 of the 3GPP specification, a UE 104 is
configured with two subframe sets for measuring CSI. The first
subframe set C.sub.CSI,0 is referred to as S1 656 herein. The
second subframe set C.sub.CSI,1 is referred to as S2 657 herein.
For a UE 104 in transmission mode 10, one subframe 655 belongs to
either S1 656 or S2 657 but not both. A dedicated RRC configuration
can identify the set of subframes 655 for Type 2 channel
measurement, which is referred to as S3 662. In one example, the UE
104 may assume that S3 662 is the same as the set of subframes 655
associated with the CSI-RS resources corresponding to the CSI
process. In another example, the UE 104 is configured with S3 662
independent of the set of subframes 655 associated with the CSI-RS
resources corresponding to the CSI process. A dedicated RRC
configuration can identify the set of subframes 655 for Type 2
interference measurement, which is referred to as S4.
The valid downlink subframes 658 for S1 656 are illustrated. The
valid downlink subframes 659 for S2 657 are also illustrated. The
subframes 660 that the UE 104 is configured to receive a reference
signal are labeled with `z` and the observations/measurements 661
of the reference signal by the UE 104 are labeled m. The valid
downlink subframes 663 for S3 662 are also illustrated.
The procedure for periodic reporting of Type 2 CSI reports is the
same for cases when one CSI process is used for both Type 1
measurement/reporting and Type 2 measurement/reporting and for
cases when a dedicated CSI process is used for either Type 1 CSI
reporting or Type 2 CSI reporting. A dedicated RRC configuration
may determine the periodicity 666 and relative reporting offset
667. For each reporting instance 664, the UE 104 may identify the
corresponding CSI reference resource 665. The UE 104 may then
generate the Type 2 periodic CSI report 122 based on the non-zero
power CSI-RS corresponding to the CSI process in the CSI reference
resource 665. The UE 104 may further include interference
measurement when generating the Type 2 periodic CSI report 122
based on at least the configured resources for interference
measurement in the CSI reference resource 665.
In the Figure, the UE 104 is configured for periodic reporting with
a periodicity 666 of 4 ms (4 subframes 655, where each subframe 655
has a duration of 1 ms) and an offset of 3 subframes 655 (or 3 ms).
For the periodic Type 2 CSI reporting scheduled in the uplink
subframe 7 of radio frame k+3, the UE 104 identifies the CSI
reference resource 665 for Type 2 CSI reporting to be the subframe
3 in radio frame k+3. The UE 104 generates the periodic Type 2 CSI
report 122 for the CSI reference resource 665 (i.e., subframe 3 in
radio frame k+3) based on the non-zero power CSI-RS and the CSI-RS
resources corresponding to the CSI process in subframe 3 of radio
frame k+3. The UE 104 may also include the interference measurement
when generating the Type 2 periodic CSI report 122, based on at
least the configured resources for interference measurement in
subframe 3 of radio frame k+3.
For a UE 104 in transmission mode 10 or transmission mode 11 (or
any transmission mode that enables Type 2 measurement), the UE 104
may derive the interference measurements for computing the CQI
value reported in uplink subframe n and corresponding to a CSI
process based on the interference measurement signal only on
subframe n-delta within the configured CSI-IM resource associated
with the CSI process. The subframe n-delta may be a CSI reference
resource 665 subframe (i.e., subframe n-n.sub.CQI.sub.--.sub.ref).
This interference measurement is referred to as a Type 2
interference measurement. The interference measurement signal may
be a zero-power CSI-RS.
For a UE 104 in transmission mode 10 or transmission mode 11 (or
any transmission mode that enables Type 2 measurement), the UE 104
may derive the channel measurement for computing the CQI value
reported in uplink subframe n and corresponding to a CSI process
based on only a non-zero power CSI-RS only on subframe n-delta
within the configured CSI-RS resource associated with the CSI
process. The subframe n-delta may be a CSI reference resource 665
subframe (i.e., subframe n-n.sub.CQI.sub.--.sub.ref). This channel
measurement is referred to as a Type 2 channel measurement. A Type
2 CSI measurement may include a Type 2 channel measurement, a Type
2 interference measurement, or both.
For Type 1 and Type 2 periodic CSI reporting,
n.sub.CQI.sub.--.sub.ref is the smallest value greater than or
equal to p, such that the subframe n-n.sub.CQI.sub.--.sub.ref
corresponds to a valid downlink subframe 665. For FDD, p=5. For TDD
with up to three CSI processes, p=4. For TDD with more than three
CSI processes, p=5.
In Type 1 channel measurement, a UE 104 may derive the channel
measurement for computing the CQI value reported in uplink subframe
n (and corresponding to a CSI process) based on only the non-zero
power CSI-RS within a configured CSI-RS resource associated with
the CSI process.
As used herein, Type 2 CSI reporting may be computed based on a) a
combination of Type 1 channel measurement and Type 2 interference
measurement, b) a combination of Type 2 channel measurement and
Type 2 interference measurement or c) a combination of Type 2
channel measurement and Type 2 interference measurement. The valid
downlink subframe 665 may be in a set of subframes 665 for a Type 1
interference measurement. The valid downlink subframe 665 may also
be in a set of subframes 665 in which the CSI-IM resource is
configured. Type 1 interference measurement is defined by the UE
104 deriving the interference measurements for computing the CQI
value reported in uplink subframe n (corresponding to a CSI
process) based on only the zero power CSI-RS within the configured
CSI-IM resource associated with the CSI process. Unlike a Type 1
interference measurement, a Type 2 interference measurement may not
be restricted to the zero power CSI-RS within the configured CSI-IM
resource associated with the CSI process and may be based on the
interference measurement signal only on subframe n-delta within the
configured CSI-IM resource associated with the CSI process.
FIG. 7 illustrates the procedures for determining the CSI reference
resources for aperiodic Type 2 CSI measurement/reporting. Multiple
radio frames 775 are illustrated. Each radio frame 775 may include
ten subframes 755, numbered from 0 to 9. The subframe set S1 756,
the subframe set S2 757 and the subframe set S3 762 are
illustrated. Further, the valid downlink subframes 758 for S1 756,
the valid downlink subframes 759 for S2 757 and the valid downlink
subframes 763 for S3 are illustrated.
To trigger aperiodic CSI reporting, the eNB 102 sends an uplink DCI
(e.g., DCI format 0 or 4) that includes a field requesting
aperiodic CSI reporting. If one CSI process is used for both Type 1
CSI reporting and Type 2 CSI reporting, then the aperiodic CSI
report may include only Type 1, only Type 2 or both Type 1 and Type
2 CSI reports. The CSI report may also include multiple Type 2 CSI
reports. In one configuration, one bit may indicate whether the
report includes Type 2 reports or not, as illustrated in Table 6
below.
TABLE-US-00007 TABLE 6 Type Indicator Bit Aperiodic Report Includes
0 Only Type 1 CSI reports 1 Both Type 1 and Type 2 CSI reports
An additional one or two bits can be used to signal a collection of
CSI reports as given in Table 3 above. It is also possible to not
include the type indicator bit. Thus, the CSI request field of two
bits may indicate sets of CSI reports including Type 1, Type 2 or
both Type 1 and Type 2 CSI reports as illustrated in Table 7
below.
TABLE-US-00008 TABLE 7 Value of CSI request field Description `00`
Aperiodic CSI report of Type 1 for a set of CSI process(es)
configured by higher layers for serving cell `01` Aperiodic CSI
reports of Type 1 and Type 2 is triggered for a set of CSI
process(es) configured by higher layers for serving cell `10`
Aperiodic CSI report is triggered for a 1.sup.st set of CSI
process(es) configured by higher layers `11` Aperiodic CSI report
of Type 2 for a set of CSI process(es) configured by higher layers
for serving cell
If a CSI process can be configured with only one CSI reporting
type, then there is no need for the type indicator bit in the
uplink DCI. In this case, the CSI request field in the uplink DCI
can be used for identifying the aperiodic CSI reports as
illustrated in Table 8 below.
TABLE-US-00009 TABLE 8 Value of CSI request field Description `00`
No aperiodic CSI report is triggered `01` Aperiodic CSI report is
triggered for a set of CSI process(es) configured by higher layers
for serving cell `10` Aperiodic CSI report is triggered for a
1.sup.st set of CSI process(es) configured by higher layers `11`
Aperiodic CSI report is triggered for a 2.sup.nd set of CSI
process(es) configured by higher layers
The number of Type 2 CSI reports in an aperiodic CSI report may be
configured by dedicated RRC signaling.
The subframes 769 where an aperiodic Type 2 CSI request is
transmitted are illustrated. The scheduled subframes 770 for
aperiodic CSI reporting are also illustrated. The CSI reference
resource subframes 771 are further illustrated. For aperiodic
reporting with X number of Type 2 CSI reports 122 (i.e., r1, r2,
r3, . . . rX) included in the UCI, n.sub.CQI.sub.--.sub.ref is
evaluated for each Type 2 CSI report 122. For report r1,
n.sub.CQI.sub.--.sub.ref.sub.--.sub.1 is the smallest value greater
than or equal to p, such that subframe
n-n.sub.CQI.sub.--.sub.ref.sub.--.sub.1 corresponds to a valid
downlink subframe 763, with the above candidates for p. Likewise,
for report r2, n.sub.CQI.sub.--.sub.ref.sub.--.sub.2 is the
smallest value greater than or equal to
n.sub.CQI.sub.--.sub.ref.sub.--.sub.1, such that subframe
n-n.sub.CQI.sub.--.sub.ref.sub.--.sub.2 corresponds to a valid
downlink subframe 763. The ith report (i.e., ri), 1<i.ltoreq.X,
denoted by n.sub.CQI.sub.--.sub.ref.sub.--.sub.i, is the smallest
value greater than n.sub.CQI.sub.--.sub.ref.sub.--.sub.i-1 such
that subframe n-n.sub.CQI.sub.--.sub.ref.sub.--.sub.i corresponds
to a valid downlink subframe 763.
A downlink subframe 755 is considered to be valid if a) the
downlink subframe 755 is configured as a downlink subframe 755 for
that UE 104, b) except for transmission mode 9 or 10, the downlink
subframe 755 is not an MBSFN subframe (discussed below), c) the
downlink subframe 755 does not include a DwPTS field in cases where
the length of DwPTS is 7680T.sub.s and less, d) the downlink
subframe 755 does not fall within a configured measurement gap for
that UE 104, and e) specific parameters for Type 1 CSI reporting
and Type 2 CSI reporting are met. For Type 1 periodic CSI
reporting, the additional specific parameters required are that a
downlink subframe 755 is considered to be valid if the downlink
subframe 755 is an element of the CSI subframe set linked to the
periodic CSI report when that UE 104 is configured with CSI
subframe sets.
In a multimedia broadcast/multicast service (MBMS) network, the
same content may be transmitted simultaneously in a specific area
(referred to as an MBMS service area) which may geographically
include multiple transmission points (TPs) or eNBs 102. If the
transmissions of all transmission points (TPs) are time
synchronized, from the perspective of a UE 104, the transmissions
appear to originate from a single transmission point (TP). This
transmission is referred to as a MBMBS single-frequency network
(MBSFN).
For Type 2 periodic and aperiodic CSI reporting, the additional
specific criteria required (for a subframe 755 to be considered a
valid downlink subframe 755) are a) that the downlink subframe 755
is in the set of subframes 755 for Type 2 channel measurement
(i.e., S3 762), b) the downlink subframe 755 is in the set of
subframes 755 in which the reference signal (e.g., the CSI-RS
resource associated with the CSI process) is configured, c) the
downlink subframe 755 is in the set of subframes 755 for Type 2
channel measurement if the set of subframes 755 for Type 2 channel
measurement is configured, d) the downlink subframe 755 is in the
set of subframes 755 for a Type 2 interference measurement (i.e.,
the subset S4 which is similar to the subset S3 762) or e) the
downlink subframe 755 is in the set of subframes 755 in which the
CSI-IM resource is configured.
Depending on the method for computing a Type 2 CSI report (e.g.,
based on a Type 1 channel measurement and a Type 2 interference
measurement, based on a Type 2 channel measurement and a Type 2
interference measurement, or based on a Type 2 channel measurement
and a Type 1 interference measurement), a combination of the above
criteria might be applied for determining a valid downlink subframe
755.
As an example, the UE 104 may receive an uplink DCI with an
aperiodic CSI reporting request in subframe 1 of radio frame k+3.
The PUSCH resources are scheduled for a transmission of an
aperiodic CSI report in subframe 6 of radio frame k+3. Moreover,
the UE 104 is configured by RRC signaling to include two Type 2 CSI
reports 122 in the aperiodic CSI reporting. The UE 104 may identify
the CSI reference resource 771 for the first Type 2 CSI report 122
(which is subframe 8 of radio frame k+2) and the second CSI
reference resource 771 for the second Type 2 CSI report 122 (which
is subframe 9 of radio frame k+2) (e.g., based on
n.sub.CQI.sub.--.sub.ref and the valid downlink subframe 775
definition described above).
The UE 104 may generate a first Type 2 CSI report 122 based on the
non-zero power CSI-RS within the configured CSI-RS resource
corresponding to the CSI process in subframe 8 of radio frame k+2.
The UE 102 may further include interference measurements when
generating the first Type 2 CSI report 122, based on at least the
configured resources for interference measurement in subframe 8 of
radio frame k+2. The UE 104 may also generate a second Type 2 CSI
report 122 based on the non-zero power CSI-RS within the configured
CSI-RS resource corresponding to the CSI process in subframe 9 of
radio frame k+2. The UE 104 may include interference measurements
when generating the second Type 2 CSI report 122, based on at least
the configured resources for interference measurement in subframe 9
of radio frame k+2. For this example, a combination of Type 2
channel measurement and Type 1 interference measurement is used.
However, a similar method may also be applied to a combination of
Type 1 channel measurement and Type 2 interference measurement by
replacing the valid downlink subframe 763 for S3 762 with a valid
downlink subframe for S4 (not shown). The UE 104 may generate a
first Type 2 CSI report 122 based on the CSI-IM resources
corresponding to the CSI process in subframe 8 of radio frame k+2.
The UE 104 may also generate a second Type 2 CSI report 122 based
on the CSI-IM corresponding to the CSI process in subframe 9 of
radio frame k+2. Also, a similar method may be applied using a
combination of Type 2 channel measurement and Type 2 interference
measurement on a CSI reference resource that is a valid downlink
subframe 755 considering the criteria related to both channel
measurement and interference measurements.
FIG. 8 illustrates various components that may be utilized in a
user equipment (UE) 804. The user equipment (UE) 804 may be
utilized as the user equipment (UE) 104 illustrated previously. The
user equipment (UE) 804 includes a processor 854 that controls
operation of the user equipment (UE) 804. The processor 854 may
also be referred to as a CPU. Memory 874, which may include both
read-only memory (ROM), random access memory (RAM) or any type of
device that may store information, provides instructions 856a and
data 858a to the processor 854. A portion of the memory 874 may
also include non-volatile random access memory (NVRAM).
Instructions 856b and data 858b may also reside in the processor
854. Instructions 856b and/or data 858b loaded into the processor
854 may also include instructions 856a and/or data 858a from memory
874 that were loaded for execution or processing by the processor
854. The instructions 856b may be executed by the processor 854 to
implement the systems and methods disclosed herein.
The user equipment (UE) 804 may also include a housing that
includes a transmitter 872 and a receiver 873 to allow transmission
and reception of data. The transmitter 872 and receiver 873 may be
combined into a transceiver 871. One or more antennas 806a-n are
attached to the housing and electrically coupled to the transceiver
871. An antenna port may be realized by one or more antennas.
The various components of the user equipment (UE) 804 are coupled
by a bus system 877, which may include a power bus, a control
signal bus, and a status signal bus, in addition to a data bus.
However, for the sake of clarity, the various buses are illustrated
in FIG. 8 as the bus system 877. The user equipment (UE) 804 may
also include a digital signal processor (DSP) 875 for use in
processing signals. The user equipment (UE) 804 may also include a
communications interface 876 that provides user access to the
functions of the user equipment (UE) 804. The user equipment (UE)
804 illustrated in FIG. 8 is a functional block diagram rather than
a listing of specific components.
FIG. 9 illustrates various components that may be utilized in an
eNB 902. The eNB 902 may be utilized as the eNode B 102 illustrated
previously. The eNB 902 may include components that are similar to
the components discussed above in relation to the user equipment
(UE) 804, including a processor 978, memory 986 that provides
instructions 979a and data 980a to the processor 978, instructions
979b and data 980b that may reside in or be loaded into the
processor 978, a housing that includes a transmitter 982 and a
receiver 984 (which may be combined into a transceiver 981), one or
more antenna ports 908a-n electrically coupled to the transceiver
981, a bus system 992, a DSP 988 for use in processing signals, a
communications interface 990, antennas 910a-n and so forth.
Unless otherwise noted, the use of `/` above represents the phrase
"and/or."
The functions described herein may be implemented in hardware,
software, firmware or any combination thereof. If implemented in
software, the functions may be stored as one or more instructions
on a computer-readable medium. The term "computer-readable medium"
refers to any available medium that can be accessed by a computer
or a processor. The term "computer-readable medium," as used
herein, may denote a computer- and/or processor-readable medium
that is non-transitory and tangible. By way of example, and not
limitation, a computer-readable or processor-readable medium may
comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage,
magnetic disk storage or other magnetic storage devices, or any
other medium that can be used to carry or store desired program
code in the form of instructions or data structures and that can be
accessed by a computer or processor. Disk and disc, as used herein,
includes compact disc (CD), laser disc, optical disc, digital
versatile disc (DVD), floppy disk and Blu-ray.RTM. disc where disks
usually reproduce data magnetically, while discs reproduce data
optically with lasers.
Each of the methods disclosed herein comprises one or more steps or
actions for achieving the described method. The method steps and/or
actions may be interchanged with one another and/or combined into a
single step without departing from the scope of the claims. In
other words, unless a specific order of steps or actions is
required for proper operation of the method that is being
described, the order and/or use of specific steps and/or actions
may be modified without departing from the scope of the claims.
As used herein, the term "determining" encompasses a wide variety
of actions and, therefore, "determining" can include calculating,
computing, processing, deriving, investigating, looking up (e.g.,
looking up in a table, a database or another data structure),
ascertaining and the like. In addition, "determining" can include
receiving (e.g., receiving information), accessing (e.g., accessing
data in a memory) and the like. Also, "determining" can include
resolving, selecting, choosing, establishing and the like.
The phrase "based on" does not mean, "based only on," unless
expressly specified otherwise. In other words, the phrase "based
on" describes both "based only on" and "based at least on."
The term "processor" should be interpreted broadly to encompass a
general purpose processor, a central processing unit (CPU), a
microprocessor, a digital signal processor (DSP), a controller, a
microcontroller, a state machine and so forth. Under some
circumstances, a "processor" may refer to an application specific
integrated circuit (ASIC), a programmable logic device (PLD), a
field programmable gate array (FPGA), etc. The term "processor" may
refer to a combination of processing devices, e.g., a combination
of a DSP and a microprocessor, a plurality of microprocessors, one
or more microprocessors in conjunction with a DSP core or any other
such configuration.
The term "memory" should be interpreted broadly to encompass any
electronic component capable of storing electronic information. The
term memory may refer to various types of processor-readable media
such as random access memory (RAM), read-only memory (ROM),
non-volatile random access memory (NVRAM), programmable read-only
memory (PROM), erasable programmable read-only memory (EPROM),
electrically erasable PROM (EEPROM), flash memory, magnetic or
optical data storage, registers, etc. Memory is said to be in
electronic communication with a processor if the processor can read
information from and/or write information to the memory. Memory may
be integral to a processor and still be said to be in electronic
communication with the processor.
The terms "instructions" and "code" should be interpreted broadly
to include any type of computer-readable statement(s). For example,
the terms "instructions" and "code" may refer to one or more
programs, routines, sub-routines, functions, procedures, etc.
"Instructions" and "code" may comprise a single computer-readable
statement or many computer-readable statements.
Software or instructions may also be transmitted over a
transmission medium. For example, if the software is transmitted
from a website, server, or other remote source using a coaxial
cable, fiber optic cable, twisted pair, digital subscriber line
(DSL) or wireless technologies such as infrared, radio, and
microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio and microwave
are included in the definition of transmission medium.
It is to be understood that the claims are not limited to the
precise configuration and components illustrated above. Various
modifications, changes and variations may be made in the
arrangement, operation and details of the systems, methods, and
apparatus described herein without departing from the scope of the
claims.
* * * * *