U.S. patent application number 13/997595 was filed with the patent office on 2014-08-07 for signaling for configuration of downlink coordinated multipoint communications.
The applicant listed for this patent is Alexei Davydov, Kamran Etemad, Alexander Maltsev, Gregory Morozov. Invention is credited to Alexei Davydov, Kamran Etemad, Alexander Maltsev, Gregory Morozov.
Application Number | 20140219115 13/997595 |
Document ID | / |
Family ID | 48047768 |
Filed Date | 2014-08-07 |
United States Patent
Application |
20140219115 |
Kind Code |
A1 |
Etemad; Kamran ; et
al. |
August 7, 2014 |
SIGNALING FOR CONFIGURATION OF DOWNLINK COORDINATED MULTIPOINT
COMMUNICATIONS
Abstract
Embodiments of the present disclosure describe devices, methods,
computer-readable media, and systems configurations for
configuration of downlink coordinated multipoint (CoMP)
communications in a wireless communication network. A user
equipment (UE) may receive, from an evolved Node B (eNB), a radio
resource control (RRC) transmission including channel state
informations (CSI) reference signal (RS) parameters for a plurality
of transmission points. The UE may subsequently receive a medium
access control (MAC) control element (CE) including a plurality of
index bits corresponding to one or more activated transmission
points of the plurality of transmission points for which the
feedback module is to generate CSI-RS feedback. The eNB may
dynamically update the transmission points that are activated for
CSI-RS feedback. The UE may receive another MAC CE from the eNB to
notify the UE of the updated set of activated transmission
points.
Inventors: |
Etemad; Kamran; (Potomac,
MD) ; Davydov; Alexei; (Nizhny Novgorod, RU) ;
Maltsev; Alexander; (Nizhny Novgorod, RU) ; Morozov;
Gregory; (Nizhny Novgorod, RU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Etemad; Kamran
Davydov; Alexei
Maltsev; Alexander
Morozov; Gregory |
Potomac
Nizhny Novgorod
Nizhny Novgorod
Nizhny Novgorod |
MD |
US
RU
RU
RU |
|
|
Family ID: |
48047768 |
Appl. No.: |
13/997595 |
Filed: |
June 8, 2012 |
PCT Filed: |
June 8, 2012 |
PCT NO: |
PCT/US2012/041618 |
371 Date: |
June 24, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61595576 |
Feb 6, 2012 |
|
|
|
Current U.S.
Class: |
370/252 |
Current CPC
Class: |
H04L 25/0224 20130101;
H04W 4/70 20180201; H04W 28/0236 20130101; H04W 48/06 20130101;
H04B 7/024 20130101; H04L 47/283 20130101; H04W 24/10 20130101;
H04L 47/122 20130101; H04L 47/26 20130101; H04W 76/18 20180201;
H04W 28/0289 20130101; H04W 76/36 20180201; H04L 25/0204 20130101;
H04W 28/0215 20130101; H04L 47/14 20130101; H04L 1/0026 20130101;
H04W 28/08 20130101; H04L 1/06 20130101; H04L 2001/0093 20130101;
H04W 28/12 20130101 |
Class at
Publication: |
370/252 |
International
Class: |
H04W 24/10 20060101
H04W024/10; H04B 7/02 20060101 H04B007/02 |
Claims
1-53. (canceled)
54. An apparatus to be employed by a user equipment (UE), the
apparatus comprising: a communications module configured to
communicate with an evolved NodeB (eNB) over a wireless
communications network; a feedback module coupled to the
communications module and configured to: receive a radio resource
control (RRC) transmission including channel state information
(CSI) reference signal (RS) parameters for a plurality of
transmission points; and receive a medium access control (MAC)
control element (CE) including a plurality of index bits
corresponding to one or more activated transmission points of the
plurality of transmission points for which the feedback module is
to generate CSI-RS feedback.
55. The apparatus of claim 54, wherein the feedback module is
further configured to: generate CSI-RS feedback for the activated
transmission points based on the CSI-RS parameters; and transmit
the CSI-RS feedback for one or more of the activated transmission
points to the eNB.
56. The apparatus of claim 55, wherein the RRC transmission further
includes a maximum number, and wherein the feedback module is
further configured to: select a number of the activated
transmission points based on quality of respective transmissions,
wherein the number is less than or equal to the maximum number; and
transmit the CSI-RS feedback for the selected transmission
points.
57. The apparatus of claim 54, wherein the CSI-RS parameters
include a CSI-RS bandwidth parameter for the individual
transmission points.
58. The apparatus of claim 54, wherein the RRC transmission further
includes cell-specific frame structure parameters for one or more
cells to which the individual transmission points belong.
59. The apparatus of claim 54, wherein the MAC CE includes: a MAC
protocol data unit (PDU) subheader with a logical channel
identifier (LCID) to identify the MAC CE as related to activation
or deactivation of CSI feedback for CoMP configuration; and a body
including the plurality of index bits.
60. The apparatus of claim 54, wherein individual index bits
correspond to individual CSI-RS resources of the transmission
points to indicate if the CSI-RS resources are active for CSI
feedback.
61. The apparatus of claim 54, wherein the index bits point to a
bitmap of a pre-defined table including a plurality of bitmaps, the
bitmap indicating the activated transmission points.
62. The apparatus of claim 54, wherein the MAC CE further includes
one or more CoMP-mode bits indicating a CoMP mode to be used by the
UE.
63. The apparatus of claim 62, wherein the MAC CE includes six
index bits and one CoMP-mode bit.
64. The apparatus of claim 62, wherein the MAC CE includes twelve
index bits, two CoMP-mode bits, one bit to indicate if the MAC CE
corresponds to a downlink configuration or an uplink configuration,
and one bit to enable an autonomous selection of a subset of
activated CSI-RS resources for reporting by the UE.
65. An apparatus for managing coordinated multipoint (CoMP)
communications with a user equipment on a wireless communications
network, the apparatus comprising: a communications module
configured to communicate with the UE over the wireless
communications network; a CoMP management module coupled to the
communications module and configured to: transmit CoMP
configuration parameters to the UE, the CoMP configuration
parameters including channel state information (CSI) reference
signal (RS) parameters for individual transmission points of a
candidate measurement set including a plurality of transmission
points, the CSI-RS parameters including a CSI-RS bandwidth
parameter; and transmit a transmission to the UE to identify
individual transmission points of the candidate measurement set for
which the UE is to generate CSI-RS feedback based on the CSI-RS
bandwidth parameter.
66. The apparatus of claim 65, wherein the transmission identifying
the individual transmission points for which the UE is to generate
CSI feedback includes a medium access control (MAC) control element
(CE) having a plurality of index bits corresponding to one or more
activated transmission points of the candidate measurement set for
which the UE is to generate the CSI-RS feedback.
67. The apparatus of claim 66, wherein individual index bits
correspond to individual transmission points of the candidate
measurement set to indicate if a CSI-RS resource of the individual
transmission point is active for CSI feedback.
68. The apparatus of claim 66, wherein the index bits point to a
bitmap of a pre-defined table including a plurality of bitmaps.
69. The apparatus of claim 66, wherein the MAC CE further includes
a CoMP-mode bit having a first value if a CoMP mode to be used by
the UE is joint transmission.
70. The apparatus of claim 66, wherein the MAC CE further includes
a pair of CoMP-mode bits to indicate if a CoMP mode to be used by
the UE is joint transmission, dynamic point selection, or
coordinated scheduling/coordinated beamforming.
71. The apparatus of claim 66, wherein the MAC CE includes a first
bit to indicate if the MAC CE corresponds to a downlink
configuration or an uplink configuration.
72. One or more non-transitory computer-readable media having
instructions, stored thereon, that, when executed cause a user
equipment (UE) to: receive, via radio resource control (RRC)
signaling, channel state information (CSI) reference signal (RS)
parameters for a plurality of transmission points; and receive a
medium access control (MAC) control element (CE) to identify one or
more activated transmission points, of the plurality of
transmission points, for which the UE is to generate CSI-RS
feedback.
73. The one or more computer-readable media of claim 72, wherein
the instructions, when executed, further cause the UE to: generate
CSI-RS feedback for the activated transmission points based on the
received CSI-RS parameters; and transmit the CSI-RS feedback for
one or more of the activated transmission points to the eNB.
74. The one or more computer-readable media of claim 72, wherein
the MAC CE includes a plurality of index bits, wherein individual
index bits correspond to individual transmission points of the CoMP
Measurement Set to indicate if the individual transmission point is
active for CSI feedback.
75. The one or more computer-readable media of claim 72, wherein
the MAC CE includes a plurality of index bits, wherein the index
bits point to a bitmap of a pre-defined table including a plurality
of bitmaps, the bitmap indicating the activated transmission
points.
76. The one or more computer-readable media of claim 72, wherein
the MAC CE further indicates a CoMP mode to be used by the UE.
77. A method to manage coordinated multi-point (CoMP)
communications with a user equipment (UE) on a wireless
communications network comprising: transmitting, to the UE via
radio resource control (RRC) signaling, channel state information
(CSI) reference signal (RS) parameters for a plurality of
transmission points; and transmitting, to the UE, a medium access
control (MAC) control element (CE) including a plurality of index
bits that point to a bitmap of a pre-defined table including a
plurality of bitmaps, the bitmap indicating one or more activated
transmission points of the plurality of transmission points for
which the UE is to generate CSI-RS feedback.
78. The method of claim 77, wherein individual bits of the bitmap
correspond to individual transmission points of the CoMP
Measurement Set to indicate if the individual transmission point is
active for CSI feedback.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional
Patent Application No. 61/595,576, filed Feb. 6, 2012, entitled
"ADVANCED WIRELESS
[0002] COMMUNICATION SYSTEMS AND TECHNIQUES," the entire disclosure
of which is hereby incorporated by reference.
FIELD
[0003] Embodiments of the present invention relate generally to the
field of communications, and more particularly, to signaling for
configuration of downlink coordinated multipoint
communications.
BACKGROUND
[0004] Coordinated multipoint (CoMP) systems have been developed in
order to improve various operational parameters in wireless
networks. There are three types of CoMP systems: joint transmission
(JT); dynamic point selection (DPS); and cooperative scheduling and
cooperative beamforming (CS/CB). In JT CoMP, both a serving point,
e.g., an enhanced node base station (eNB), and a coordinating
point, e.g., another eNB, may send the same data to a user
equipment (UE). In DPS CoMP, a transmission point may be
dynamically selected among different candidates, e.g., a macro-node
eNB and a pico-node eNB. In CS/CB CoMP, coordinating nodes may
suppress interference of interfering channels. Effective management
of CoMP communications with a UE may require definition of various
CoMP sets of transmission points. However, the UE may not provide
sufficient feedback to allow the eNB to effectively determine the
CoMP sets.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Embodiments will be readily understood by the following
detailed description in conjunction with the accompanying drawings.
To facilitate this description, like reference numerals designate
like structural elements. Embodiments are illustrated by way of
example and not by way of limitation in the figures of the
accompanying drawings.
[0006] FIG. 1 schematically illustrates a wireless communication
network in accordance with various embodiments.
[0007] FIG. 2 is a block diagram illustrating a user equipment in
accordance with various embodiments.
[0008] FIG. 3 is a block diagram illustrating a base station in
accordance with various embodiments.
[0009] FIG. 4A illustrates example abstract syntax notation one
(ASN.1) code for an RRC transmission in accordance with various
embodiments.
[0010] FIG. 4B illustrates another example ASN.1 code for an RRC
transmission in accordance with various embodiments.
[0011] FIG. 4C illustrates yet another example ASN.1 code for an
RRC transmission in accordance with various embodiments.
[0012] FIG. 5 is a table showing logical channel identifiers
(LCIDs) for medium access control (MAC) protocol data unit (PDU)
subheaders in accordance with various embodiments.
[0013] FIG. 6 shows a body of a MAC control element (CE) including
one octet in accordance with various embodiments.
[0014] FIG. 7 shows a body of a MAC CE including two octets in
accordance with various embodiments.
[0015] FIG. 8 is a table showing example assigned fields of R-bits
of the MAC CE body of FIG. 6, in accordance with various
embodiments.
[0016] FIG. 9 is a table showing example assigned fields of R-bits
of the MAC CE body of FIG. 7, in accordance with various
embodiments.
[0017] FIG. 10 is a flowchart illustrating a method to support
downlink coordinated multipoint (CoMP) configuration that may be
performed by a user equipment in accordance with various
embodiments.
[0018] FIG. 11 is a flowchart illustrating a downlink CoMP
management method that may be performed by a base station in
accordance with various embodiments.
[0019] FIG. 12 is a block diagram illustrating an example system in
accordance with various embodiments.
DETAILED DESCRIPTION
[0020] Illustrative embodiments of the present disclosure include,
but are not limited to, methods, systems, and apparatuses for
configuring downlink coordinated multipoint (CoMP) communications
in a wireless communication network.
[0021] Various aspects of the illustrative embodiments will be
described using terms commonly employed by those skilled in the art
to convey the substance of their work to others skilled in the art.
However, it will be apparent to those skilled in the art that
alternate embodiments may be practiced with only some of the
described aspects. For purposes of explanation, specific numbers,
materials, and configurations are set forth in order to provide a
thorough understanding of the illustrative embodiments. However, it
will be apparent to one skilled in the art that alternate
embodiments may be practiced without the specific details. In other
instances, well-known features are omitted or simplified in order
not to obscure the illustrative embodiments.
[0022] Further, various operations will be described as multiple
discrete operations, in turn, in a manner that is most helpful in
understanding the illustrative embodiments; however, the order of
description should not be construed as to imply that these
operations are necessarily order dependent. In particular, these
operations need not be performed in the order of presentation.
[0023] The phrase "in some embodiments" is used repeatedly. The
phrase generally does not refer to the same embodiments; however,
it may. The terms "comprising," "having," and "including" are
synonymous, unless the context dictates otherwise. The phrase "A
and/or B" means (A), (B), or (A and B). The phrase "A/B" means (A),
(B), or (A and B), similar to the phrase "A and/or B". The phrase
"at least one of A, B and C" means (A), (B), (C), (A and B), (A and
C), (B and C) or (A, B and C). The phrase "(A) B" means (B) or (A
and B), that is, A is optional.
[0024] Although specific embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that a wide variety of alternate and/or equivalent
implementations may be substituted for the specific embodiments
shown and described, without departing from the scope of the
embodiments of the present disclosure. This application is intended
to cover any adaptations or variations of the embodiments discussed
herein. Therefore, it is manifestly intended that the embodiments
of the present disclosure be limited only by the claims and the
equivalents thereof.
[0025] As used herein, the term "module" may refer to, be part of,
or include an Application Specific Integrated Circuit (ASIC), an
electronic circuit, a processor (shared, dedicated, or group)
and/or memory (shared, dedicated, or group) that execute one or
more software or firmware programs, a combinational logic circuit,
and/or other suitable components that provide the described
functionality.
[0026] FIG. 1 schematically illustrates a wireless communication
network 100 in accordance with various embodiments. Wireless
communication network 100 (hereinafter "network 100") may be an
access network of a 3rd Generation Partnership Project (3GPP)
long-term evolution (LTE) network such as evolved universal mobile
telecommunication system (UMTS) terrestrial radio access network
(E-UTRAN). The network 100 may include a base station, e.g.,
evolved Node B (eNB) 104, configured to wirelessly communicate with
user equipment (UE) 108.
[0027] At least initially, the eNB 104 may have an established
wireless connection with the UE 108 and may operate as a serving
node for CoMP communications with the UE 108. The eNB 104 may
include one or more transmission points 112a-c that service
individual cells 116a-c of the network 100. For example,
transmission point 112a may cover a first cell 116a, transmission
point 112b may cover a second cell 116b, and transmission point
112c may cover a third cell 116c. In other embodiments, the eNB 104
may include only one transmission point and/or may only cover one
cell. The network 100 may further include one or more additional
transmission points 112d-o. In some embodiments, the transmission
points 112d-o may be remote radio heads (RRHs), also referred to as
remote radio equipment (RRE)) and/or base stations (e.g., eNBs). In
some embodiments, the transmission points 112d-o may transmit with
a lower power than eNB 104. Transmission points 112d-o may be
located in and/or associated with cells 116a-c as shown.
[0028] The transmission points 112d-o may be configured to
facilitate wireless communication with the UE 108 through
coordination with the eNB 104. The one or more additional
transmission points 112d-o may be collectively referred to as
"coordinating nodes." In some embodiments, a transmission point may
transition between coordinating and serving node roles. The serving
node and coordinating nodes may communicate with one another over a
wireless connection and/or a wired connection (e.g., a high-speed
fiber backhaul connection).
[0029] As shown in FIG. 2, the UE 108 may include a communications
module 220, a feedback module 224, and memory 228 coupled with one
another at least as shown. The communications module 220 may be
further coupled with one or more of a plurality of antennas 232 of
the UE 108 for communicating wirelessly over network 100.
[0030] The UE 108 may include any suitable number of antennas 232.
In various embodiments, the UE 108 may include at least as many
antennas 232 as a number of simultaneous spatial layers or streams
received by the UE 108 from the transmission points 112a-o,
although the scope of the present disclosure may not be limited in
this respect. The number of simultaneous spatial layers or streams
may also be referred to as transmission rank, or simply rank.
[0031] One or more of the antennas 232 may be alternately used as
transmit or receive antennas. Alternatively, or additionally, one
or more of the antennas 232 may be dedicated receive antennas or
dedicated transmit antennas.
[0032] As shown in FIG. 3, eNB 104 may include a communications
module 336 and a CoMP management module 340 coupled with one
another at least as shown. The communications module 336 may be
further coupled with one or more of a plurality of antennas 344 of
the eNB 104. The communications module 336 may communicate with
(e.g., transmit information to and/or receive information from) one
or more UEs (e.g., UE 108). In various embodiments, the eNB 104 may
include at least as many antennas 344 as a number of simultaneous
transmission streams transmitted to the UE 108, although the scope
of the present disclosure may not be limited in this respect. One
or more of the antennas 344 may be alternately used as transmit or
receive antennas. Alternatively, or additionally, one or more of
the antennas 344 may be dedicated receive antennas or dedicated
transmit antennas. Additionally, one or more of the antennas 344
may be associated with individual transmission points 112a-c (e.g.,
dedicated for communications within an individual cell 116a-c).
Alternatively, or additionally, one or more of the antennas 344 may
alternate between communicating in one or more cells 116a-c.
[0033] In some embodiments, one or more of transmission points
112d-o may have similar modules/components as eNB 104.
[0034] In various embodiments, the feedback module 224 of the UE
108 may receive a radio resource control (RRC) transmission from
the eNB 104. The RRC transmission may include CoMP configuration
parameters. For example, the RRC transmission may include channel
state information (CSI) reference signal (RS) parameters for a
plurality of transmission points (e.g., a plurality of the
transmission points 112a-o). The transmission points may be initial
candidates for CoMP communications with the UE 108. These
transmission points may be collectively referred to as a candidate
measurement set.
[0035] In various embodiments, the UE 108 may subsequently receive
a medium access control (MAC) control element (CE) that indicates
one or more of the candidate transmission points that are activated
for CSI-RS feedback. The activated transmission points may be
collectively referred to as a CoMP Measurement Set of transmission
points for which the UE 108 is to generate CSI-RS feedback. The UE
108 may generate the CSI-RS feedback for the activated transmission
points based on the CSI-RS parameters, and may transmit the CSI-RS
feedback for one or more of the activated transmission points to
the eNB 104. In some embodiments, the CSI-RS feedback may be fast
CSI-RS feedback (as opposed to long-term (average) CSI-RS
feedback).
[0036] The eNB 104 may select transmission points for a cooperating
set and a scheduled transmission point set from the transmission
points for which the eNB 104 receives the fast CSI-RS feedback
information. The cooperating set may include the transmission
points that cooperate for CoMP transmissions to the UE 108. The eNB
104 may determine the transmission points included in the
cooperating set based on the received CSI-RS feedback, other
scheduling decisions, and/or other data/factors. The cooperating
set may include one or more transmission points scheduled for
transmission to the UE 108 on a physical downlink shared channel
(PDSCH). Additionally, the cooperating set may include any
transmission points scheduled to mute (e.g., not transmit) the
PDSCH for the corresponding channel resources. The scheduled
transmission points set may include only the one or more
transmission points scheduled to transmit to the UE 108 on the
PDSCH.
[0037] The eNB 104 may dynamically update which transmission points
are included in the CoMP Measurement Set. The CoMP Measurement Set
may be updated, for example, based on the received CSI-RS feedback
information, other scheduling decisions, and/or other data/factors.
The eNB 104 may send further MAC CEs to notify the UE 108 of the
activated transmission points included in the updated CoMP
Measurement Set. The UE 108 may reference the CoMP configuration
parameters that were previously received in the RRC transmission.
Accordingly, the eNB 104 may not need to re-send the CoMP
configuration parameters. Thus, the RRC signaling and/or MAC CE may
allow dynamic activation/deactivation of CSI-RS feedback in an
efficient manner.
[0038] FIG. 4A illustrates example abstract syntax notation one
(ASN.1) code 400 for an RRC transmission in accordance with various
embodiments. The contents of the RRC transmission may be sent all
at once or in separate transmissions.
[0039] As discussed above, the RRC transmission may include CoMP
configuration parameters related to individual transmission points
and/or cells that are candidates for CoMP transmissions to the UE
108. The CoMP configuration parameters may include CSI-RS
parameters for the individual candidate transmission points. The
CSI-RS parameters may include, for example, CSI-RS resource
configuration parameters, zero-power CSI-RS configuration
parameters, uplink control channel parameters, and/or a CSI
feedback mode indicator. The CSI-RS resource configuration
parameters may include, for example, a transmit power, a
periodicity, a subframe offset, an initialization seed for
scrambling code, a number of antenna ports, and/or an index related
to the individual transmission points of the candidate measurement
set. The zero-power CSI-RS configuration parameters may include
conventional zero-power CSI-RS configuration parameters and/or
zero-power CSI-RS configuration parameters for interference
measurements.
[0040] The CSI-RS parameters may include and/or be associated with
indices corresponding to individual transmission points of the
candidate measurement set. The indices may be assigned explicitly,
and/or implicitly (e.g., based on the order of CSI-parameters in
the RRC transmission). The indices may allow the MAC CE to
efficiently activate and/or deactivate the transmission points for
CSI-RS feedback, as further discussed herein.
[0041] In some embodiments, CoMP configuration parameters in the
RRC transmission may further include a maximum number corresponding
to the maximum number of transmission points of the CoMP
Measurement Set for which the UE 108 is to transmit the CSI-RS
feedback. The UE 108 may select a number of the activated
transmission points based on a quality of the respective
transmissions (e.g., based on the generated CSI-RS feedback),
wherein the number is less than or equal to the maximum number. The
UE 108 may transmit the generated CSI-RS feedback for the selected
transmission points to the eNB 104.
[0042] In some embodiments, the CoMP configuration parameters in
the RRC transmission may further include cell-specific parameters.
FIG. 4B shows one example of ASN.1 code 410 for an RRC transmission
including cell-specific parameters. An alternative example ASN.1
code 420 is shown in FIG. 4C. The parameters defined by ASN.1 code
410 and/or 420 may be included in the same RRC transmission as the
parameters included in ASN.1 code 400 and/or in a different
transmission.
[0043] The cell-specific parameters may include, for example, frame
structure parameters, such as multicast-broadcast single frequency
network (MBSFN) subframe indexes within the radio frame, a number
of antenna ports for common reference signals (CRSs), a CRS
frequency shift (e.g., 0 to 5), a subframe shift with respect to
the serving cell, a cell identifier, a number of symbols in a
physical downlink control channel (PDCCH) transmitted by the cell,
and/or positioning reference signal (PRS) parameters associated
with individual cells (e.g., cells 116a-c).
[0044] The cell-specific parameters may include a newCarrierType
parameter to indicate if the cell is configured with a new carrier
type. If multiple carrier types are defined with different
treatments in CoMP, this parameter may be enumerated with multiple
possible values (e.g., 1-4). For some carrier types, some of the
cell-specific parameters may not be relevant or applicable. Those
cell-specific parameters may or may not be included for those
carrier types.
[0045] In some embodiments, the CoMP configuration parameters in
the RRC transmission may further include a CSI-RS bandwidth
parameter for individual transmission points of the candidate
measurement set. In some embodiments, one or more of the
transmission points 112a-o may transmit with a different bandwidth
than other transmission points 112a-o. For example, higher power
transmission points may have a different bandwidth than lower power
transmission points. The bandwidth of the transmission point may
affect some feedback measurements, such as wideband CSI
measurements. Accordingly, the CSI-RS bandwidth parameter may allow
the UE 108 to account for the bandwidth of the transmission point
when generating feedback information.
[0046] In various embodiments, the CoMP configuration parameters
received via the RRC transmission may be stored by the UE 108
(e.g., in memory 228). The feedback module 224 may retrieve the
parameters from the memory 228 for the transmission points that are
activated for CSI-RS feedback by the MAC CE, as further discussed
herein.
[0047] In various embodiments, the MAC CE may include a MAC
protocol data unit (PDU) subheader with a logical channel
identifier (LCID) to identify the MAC CE as related to activation
and/or deactivation of CSI feedback for CoMP configuration. FIG. 5
shows a Table 500 with example LCIDs for various MAC CEs. As shown
in Table 500, the LCID for the MAC CE may be "11010" to indicate
CoMP Activation/Deactivation. It will be apparent that other
suitable LCIDs may be used.
[0048] The MAC CE may further include a body (also referred to as a
payload). FIG. 6 shows a MAC CE with a body 600 having eight bits
(e.g., one octet). The body 600 may include six index bits (e.g.,
C-bits C.sub.0-C.sub.5) and two R-bits (e.g., R.sub.0 and R.sub.1).
FIG. 7 shows a MAC CE with a body 700 having sixteen bits (e.g.,
two octets). The body 700 may include twelve index bits (e.g.,
C-bits C.sub.0-C.sub.11) and four R-bits (e.g., R.sub.0-R.sub.3).
Other embodiments may include any other suitable number of index
bits, R-bits, and/or total bits, and may include any other suitable
arrangement of bits.
[0049] In some embodiments, the individual index bits C.sub.i may
directly correspond to respective indices, i, of individual
transmission points (e.g., individual configured CSI-RS resources
of individual transmission points) of the candidate measurement set
as configured by the RRC transmission. The index bit may have a
first value (e.g., a logic 1) to indicate that the transmission
point is active for CSI-RS feedback, and a second value (e.g., a
logic 0) to indicate that the transmission point is not active for
CSI-RS feedback.
[0050] Alternatively, the index bits may point to a bitmap of a
pre-defined table including a plurality of bitmaps. The bitmap may
indicate the activated transmission points based on the indices of
the transmission points. This may allow a larger set of candidate
transmission points to be configured and dynamically
activated/deactivated for CSI-RS feedback. For example, the bitmap
table may be used if a maximum, M, of transmission points that will
be activated at the same time is less than the number of candidate
transmission points. For example, if M is equal to three, the
pre-defined bitmap table may include sixty-four possible 8-bit
bitmaps (corresponding to eight candidate transmission points),
with only one, two, or three bits set as activated (e.g., logic 1).
In that case, the six index bits of the MAC CE body 600 may be used
to point to one of the sixty-four possible 8-bit maps included in
the pre-defined table.
[0051] The feedback module 224 of the UE 108 may receive the MAC
CE. The feedback module 224 may then generate CSI-RS feedback
(e.g., fast CSI-RS feedback) for the activated transmission points
as indicated by the MAC CE. The feedback module 224 may then
transmit the generated CSI-RS feedback for one or more of the
activated transmission points to the eNB 104. As previously
discussed, in some embodiments, the feedback module 224 may
transmit the generated CSI-RS feedback for a number of transmission
points less than or equal to a maximum number.
[0052] In various embodiments, the R-bits may include one or more
CoMP-mode bits to indicate a CoMP mode to be used by the eNB 104
and/or UE 108. In some embodiments, the MAC CE may include a single
CoMP-mode bit that has a first value (e.g., a logic 0) if the CoMP
mode is joint transmission (JT), and a second value (e.g., a logic
1) if the CoMP mode is not joint transmission (e.g., dynamic point
selection (DPS) or coordinated scheduling/coordinated beamforming
(CS/CB)). Alternatively, the MAC CE may include a pair of CoMP-mode
bits to indicate if the CoMP mode is JT, DPS, or CS/CB.
[0053] For example, FIG. 8 is a table 800 showing fields of the
R-bits for MAC CE body 600 in accordance with one embodiment. The
MAC CE body 600 may include one CoMP-mode bit (R.sub.0) and one
reserved bit (R.sub.1). Alternatively, both R-bits of the MAC CE
body 600 may be CoMP-mode bits.
[0054] FIG. 9 is a table 900 showing example fields of the R-bits
for MAC CE body 700 in accordance with another embodiment. MAC CE
body 700 may include two CoMP-mode bits (R.sub.0 and R.sub.1) and
two reserved bits (R.sub.2 and R.sub.3). Alternatively, MAC CE body
700 may include only one CoMP-mode bit.
[0055] The UE 108 may determine a configuration of CSI-RS feedback
to use based on the CoMP mode to be used. For example, in case of
joint transmission as indicated by the one or more CoMP-mode bits,
the UE 108 may provide CSI-RS feedback for the same set of
preferred sub-bands for all CSI-RSs, provide CSI-RS feedback of the
same rank for all CSI-RS resources, use the same receive processing
to calculate rank indicator (RI), precoding matrix indicator (PMI),
and/or channel quality indicator (CQI) reports, and/or provide
inter-CSI-RS-resource feedback or CSI feedback aggregated across
multiple CSI-RS resources depending on the CoMP mode. In case of
coordinated scheduling and beamforming as indicated by the one or
more CoMP-mode bits, the UE 108 may restrict the CSI-RS feedback
the UE provides to a low rank for some CSI-RS resources.
[0056] In some embodiments, the MAC CEs having the same LCID may be
used to configure feedback for uplink CoMP as well as downlink
CoMP. In some such embodiments, the body 600 and/or 700 may include
a bit to indicate if the MAC CE corresponds to downlink CoMP
configuration or uplink CoMP configuration. For example, R.sub.1 of
MAC CE body 600 and/or R.sub.2/R.sub.3 of MAC CE body 700 may be
used to indicate the MAC CE as related to downlink or uplink
configuration.
[0057] In some embodiments, the MAC CE may further include a bit to
enable an autonomous selection of a subset of activated CSI-RS
resources for reporting by the UE 108. For example, R.sub.1 of MAC
CE body 600 and/or R.sub.2/R.sub.3 of MAC CE body 700 may be used
for this purpose. In one embodiment, R.sub.2 of MAC CE body 700 may
be used for uplink/downlink indication, and R.sub.3 may be used to
enable autonomous selection. In some cases, if autonomous selection
is activated, the UE 108 may generate CSI-RS feedback for all the
configured transmission points in the candidate measurement set
without regard to the value of the index bits. The UE 108 may then
select a number of the transmission points up to a maximum number
and transmit the CSI-RS feedback to the eNB 104 for the selected
transmission points. The UE 108 may select the transmission points
based on a quality of respective transmissions (e.g., based on the
generated CSI-RS feedback). The maximum number may be received from
the eNB 104 (e.g., in the RRC transmission discussed above),
determined by the UE 108, and/or pre-programmed for the UE 108. The
UE 108 may dynamically update the transmission points for which the
UE 108 transmits CSI-RS feedback to the eNB 104.
[0058] As mentioned above, the eNB 104 may select the cooperating
set of one or more transmission points from the CoMP Measurement
Set (e.g., the activated transmission points). The eNB 104 may
determine the transmission points included in the cooperating set
based on the received CSI-RS feedback, other scheduling decisions,
and/or other data/factors. The cooperating set may include one or
more transmission points scheduled for transmission to the UE 108
on the PDSCH (e.g., the scheduled transmission points set) and any
transmission points scheduled to mute (e.g., not transmit) on the
PDSCH for the corresponding channel resources. In some embodiments,
the identity of the cooperating set may not be transmitted to the
UE 108, since the cooperating set may include transmission points
which do not transmit to the UE 108 on the PDSCH.
[0059] In some embodiments, the eNB 104 may send a transmission to
the UE 108 to notify the UE 108 of the transmission points
scheduled for transmission to the UE 108 on the PDSCH (e.g., the
scheduled transmission points set). The UE 108 may need to be
notified of the scheduled transmission points, for example, for
some CoMP schemes such as dynamic point selection. In other
embodiments, the eNB 104 may not notify the UE 108 of the scheduled
transmission points.
[0060] The transmission to notify the UE 108 of the scheduled
transmission points may be sent on a physical channel, such as the
PDCCH. In some embodiments, the transmission may use the indices
configured for the transmission points in the RRC transmission to
notify the UE of the scheduled transmission points. The UE 108 may
use the configured CoMP configuration parameters to receive
transmissions from the scheduled transmission points.
[0061] As previously discussed, the eNB 104 (e.g., the CoMP
management module 340) may dynamically update the transmission
points included in the CoMP Measurement Set and send another MAC CE
to the UE 108 to notify the UE 108 of the updated CoMP Measurement
Set. The eNB 104 may not need to re-send the CoMP configuration
parameters, such as the CSI-RS parameters and/or cell-specific
parameters. Rather, the UE 108 may use the previously received CoMP
configuration parameters to generate the CSI-RS feedback and/or for
subsequent CoMP communications.
[0062] The eNB 104 may update the transmission points included in
the CoMP Measurement Set, for example, based on the CSI-RS fast
feedback information reported by the UE 108 for the CoMP
Measurement Set, feedback received for the candidate measurement
set (e.g., CSI-RS-based radio resource management (RRM)
measurements, CRS-based RRM measurements, and/or uplink SRS
measurements), other scheduling decisions, and/or other
data/factors. For example, if a quality of the CSI-RS feedback for
one or more of the reported transmission points is below a
threshold, the eNB 104 may seek to add and/or replace another
transmission point to the CoMP Measurement Set. The eNB 104 may
choose other transmission points to include in the CoMP Measurement
Set from the transmission points included in the candidate
measurement set. Additionally, the eNB 104 may remove one or more
transmission points from the CoMP Measurement Set based on the
CSI-RS feedback.
[0063] In some embodiments, the eNB 104 may receive ongoing (e.g.,
periodic) candidate feedback for the candidate measurement set, and
may select and/or update the CoMP Measurement Set based on the
candidate feedback. For example, the candidate feedback information
may include long-term common reference signal (CRS) feedback
information (e.g., CRS-based RRM measurements), uplink sounding
reference signal (SRS) feedback information, and/or long-term
CSI-RS feedback information (e.g., CSI-RS-based RRM
measurements).
[0064] FIG. 10 illustrates a method 1000 to support downlink CoMP
communications on a wireless communications network (e.g., network
100) in accordance with various embodiments. Method 1000 may be
performed by a UE, such as UE 108. In some embodiments, the UE may
include and/or have access to one or more computer-readable media
having instructions stored thereon, that, when executed, cause the
UE to perform the method 1000.
[0065] At 1004, the UE may receive, via radio resource control
(RRC) signaling, CoMP configuration parameters for a plurality of
transmission points that are candidates for CoMP transmission to
the UE. The CoMP configuration parameters may include CSI-RS
parameters for individual transmission points, cell-specific
parameters for one or more cells associated with the transmission
points, and/or a maximum number of transmission points for which
the UE is to transmit CSI-RS feedback.
[0066] At 1008, the UE may receive a MAC CE including a plurality
of index bits corresponding to one or more of the plurality of
transmission points that are activated for CSI-RS feedback. The MAC
CE may include a body similar to MAC CE body 600 and/or 700
discussed above.
[0067] At 1012, the UE may generate CSI-RS feedback (e.g., fast
CSI-RS feedback) for CSI-RS resources of the activated transmission
points based on the received CSI-RS parameters. At 1016, the UE may
transmit the CSI-RS feedback for one or more of the activated
transmission points to the eNB. In some embodiments, the UE may
select a number of transmission points less than or equal to the
maximum number for transmitting to the eNB.
[0068] In various embodiments, the UE may thereafter receive
another MAC CE updating the transmission points that are activated
for CSI-RS feedback. The UE may then generate the CSI-RS feedback
for the activated transmission points indicated in the updated MAC
CE.
[0069] FIG. 11 illustrates a method 1100 for managing downlink CoMP
communications with a UE (e.g., UE 108). Method 1100 may be
performed by an eNB, such as eNB 104. In some embodiments, the eNB
may include and/or have access to one or more computer-readable
media having instructions stored thereon, that, when executed,
cause the UE to perform the method 1100.
[0070] At 1104, the eNB may transmit, via RRC signaling, CoMP
configuration parameters for a plurality of transmission points
that are candidates for CoMP transmission to the UE. The CoMP
configuration parameters may include CSI-RS parameters for
individual transmission points, cell-specific parameters for one or
more cells associated with the transmission points, and/or a
maximum number of transmission points for which the UE is to
transmit CSI-RS feedback.
[0071] At 1108, the eNB may transmit a MAC CE including a plurality
of index bits corresponding to one or more of the candidate
transmission points that are activated for CSI-RS feedback. The MAC
CE may include a body similar to MAC CE body 600 and/or 700
discussed above.
[0072] At 1112, the eNB may receive CSI-RS feedback (e.g., fast
CSI-RS feedback) for one or more of the activated transmission
points. The eNB may select a cooperating set of transmission points
based on the received CSI-RS feedback. The cooperating set may
include one or more transmission points that are scheduled to
transmit on the PDSCH to the UE.
[0073] In various embodiments, the eNB may update the activated
transmission points and send another MAC CE to the UE.
[0074] The eNB 104, UE 108, and/or transmission points 112a-o
described herein may be implemented into a system using any
suitable hardware and/or software to configure as desired. FIG. 12
illustrates, for one embodiment, an example system 1200 comprising
one or more processor(s) 1204, system control logic 1208 coupled
with at least one of the processor(s) 1204, system memory 1212
coupled with system control logic 1208, non-volatile memory
(NVM)/storage 1216 coupled with system control logic 1208, a
network interface 1220 coupled with system control logic 1208, and
input/output (I/O) devices 1232 coupled with system control logic
1208.
[0075] The processor(s) 1204 may include one or more single-core or
multi-core processors. The processor(s) 1204 may include any
combination of general-purpose processors and dedicated processors
(e.g., graphics processors, application processors, baseband
processors, etc.).
[0076] System control logic 1208 for one embodiment may include any
suitable interface controllers to provide for any suitable
interface to at least one of the processor(s) 1204 and/or to any
suitable device or component in communication with system control
logic 1208.
[0077] System control logic 1208 for one embodiment may include one
or more memory controller(s) to provide an interface to system
memory 1212. System memory 1212 may be used to load and store data
and/or instructions, for example, for system 1200. System memory
1212 for one embodiment may include any suitable volatile memory,
such as suitable dynamic random access memory (DRAM), for
example.
[0078] NVM/storage 1216 may include one or more tangible,
non-transitory computer-readable media used to store data and/or
instructions, for example. NVM/storage 1216 may include any
suitable non-volatile memory, such as flash memory, for example,
and/or may include any suitable non-volatile storage device(s),
such as one or more hard disk drive(s) (HDD(s)), one or more
compact disk (CD) drive(s), and/or one or more digital versatile
disk (DVD) drive(s), for example.
[0079] The NVM/storage 1216 may include a storage resource
physically part of a device on which the system 1200 is installed
or it may be accessible by, but not necessarily a part of, the
device. For example, the NVM/storage 1216 may be accessed over a
network via the network interface 1220 and/or over Input/Output
(I/O) devices 1232.
[0080] Network interface 1220 may have a transceiver 1222 to
provide a radio interface for system 1200 to communicate over one
or more network(s) and/or with any other suitable device. The
transceiver 1222 may implement communications module 220 of UE 108
or communications module 336 of eNB 104. In various embodiments,
the transceiver 1222 may be integrated with other components of
system 1200. For example, the transceiver 1222 may include a
processor of the processor(s) 1204, memory of the system memory
1212, and NVM/Storage of NVM/Storage 1216. Network interface 1220
may include any suitable hardware and/or firmware. Network
interface 1220 may include a plurality of antennas to provide a
multiple input, multiple output radio interface. Network interface
1220 for one embodiment may include, for example, a wired network
adapter, a wireless network adapter, a telephone modem, and/or a
wireless modem.
[0081] For one embodiment, at least one of the processor(s) 1204
may be packaged together with logic for one or more controller(s)
of system control logic 1208. For one embodiment, at least one of
the processor(s) 1204 may be packaged together with logic for one
or more controllers of system control logic 1208 to form a System
in Package (SiP). For one embodiment, at least one of the
processor(s) 1204 may be integrated on the same die with logic for
one or more controller(s) of system control logic 1208. For one
embodiment, at least one of the processor(s) 1204 may be integrated
on the same die with logic for one or more controller(s) of system
control logic 1208 to form a System on Chip (SoC).
[0082] In various embodiments, the I/O devices 1232 may include
user interfaces designed to enable user interaction with the system
1200, peripheral component interfaces designed to enable peripheral
component interaction with the system 1200, and/or sensors designed
to determine environmental conditions and/or location information
related to the system 1200.
[0083] In various embodiments, the user interfaces could include,
but are not limited to, a display (e.g., a liquid crystal display,
a touch screen display, etc.), a speaker, a microphone, one or more
cameras (e.g., a still camera and/or a video camera), a flashlight
(e.g., a light emitting diode flash), and a keyboard.
[0084] In various embodiments, the peripheral component interfaces
may include, but are not limited to, a non-volatile memory port, a
universal serial bus (USB) port, an audio jack, and a power supply
interface.
[0085] In various embodiments, the sensors may include, but are not
limited to, a gyro sensor, an accelerometer, a proximity sensor, an
ambient light sensor, and a positioning unit. The positioning unit
may also be part of, or interact with, the network interface 1220
to communicate with components of a positioning network, e.g., a
global positioning system (GPS) satellite.
[0086] In various embodiments, the system 1200 may be a mobile
computing device such as, but not limited to, a laptop computing
device, a tablet computing device, a netbook, a smartphone, etc. In
various embodiments, system 1200 may have more or less components,
and/or different architectures.
[0087] Although certain embodiments have been illustrated and
described herein for purposes of description, a wide variety of
alternate and/or equivalent embodiments or implementations
calculated to achieve the same purposes may be substituted for the
embodiments shown and described without departing from the scope of
the present disclosure. This application is intended to cover any
adaptations or variations of the embodiments discussed herein.
Therefore, it is manifestly intended that embodiments described
herein be limited only by the claims and the equivalents
thereof.
* * * * *