U.S. patent number RE48,530 [Application Number 15/997,317] was granted by the patent office on 2021-04-20 for method and system for dynamic cell configuration.
This patent grant is currently assigned to Huawei Technologies Co., Ltd.. The grantee listed for this patent is Huawei Technologies Co., Ltd.. Invention is credited to Jianglei Ma, Wen Tong, Peiying Zhu.
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United States Patent |
RE48,530 |
Ma , et al. |
April 20, 2021 |
Method and system for dynamic cell configuration
Abstract
An apparatus for adapting hyper cells in response to changing
conditions of a cellular network is disclosed. During operation,
the apparatus collects data regarding network conditions of the
cellular network. In accordance with the collected network
condition data, the apparatus changes an association of a transmit
point from a second cell ID of a second hyper cell to a first cell
ID of a first hyper cell. Virtual data channels, broadcast common
control channel and virtual dedicated control channel, transmit
point optimization, UE-centric channel sounding and measurement,
and single frequency network synchronization are also
disclosed.
Inventors: |
Ma; Jianglei (Ottawa,
CA), Zhu; Peiying (Kanata, CA), Tong;
Wen (Ottawa, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Huawei Technologies Co., Ltd. |
Shenzhen |
N/A |
CN |
|
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Assignee: |
Huawei Technologies Co., Ltd.
(Shenzhen, CN)
|
Family
ID: |
49774846 |
Appl.
No.: |
15/997,317 |
Filed: |
June 4, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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15261269 |
Sep 9, 2016 |
RE47191 |
|
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Reissue of: |
13533631 |
Jun 26, 2012 |
8838119 |
Sep 16, 2014 |
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Reissue of: |
13533631 |
Jun 26, 2012 |
8838119 |
Sep 16, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
16/04 (20130101); H04W 16/24 (20130101) |
Current International
Class: |
H04W
16/18 (20090101); H04W 16/04 (20090101); H04W
16/24 (20090101) |
Field of
Search: |
;455/446,466,422.1,426.1,426.2,562.1,452.1,453,423
;370/328,331-332 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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Jan 2012 |
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Jan 2012 |
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Mar 2011 |
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WO |
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May 2014 |
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Other References
3GPP TR 36.819 v11.1.0 (Dec. 2011), 3rd Generation Partnership
Project; Technical Specification Group Radio Access Network;
Coordinated multi-point operation for LTE physical layer aspects
(Release 11), 69 pages. cited by applicant .
3GPP TSG RAN WG1 Meeting #66bis, R1-113035, "Considerations on RRH
subset selection mechanism," Potevio, Oct. 10-14, 2011, 3 pages.
cited by applicant .
3GPP TSG RAN WG1 meeting#68, R1-120496, "CoMP Operation and UE
Mobility," Alcatel-Lucent, Alcatel-Lucent Shanghai Bell, Feb. 6-10,
2012, 5 pages. cited by applicant .
Catt, "Further considerations on scenario 3 and 4," 3GPP TSG RAN
WG1 Meeting #64, R1-110720, Taipei, Feb. 21-25, 2011, 3 pages.
cited by applicant .
Fujitsu, "Consideration of antenna virtualization in DL MIMO
scenario B," 3GPP TSG RAN WG1 meeting #66bis, R1-113500, Zhuhai,
China, Oct. 10-14, 2011, 4 pages. cited by applicant .
Samsung, "Interference Measurement Resource for Downlink CoMP",
3GPP TSG RAN WG1 #68ibs, R1-121627, Mar. 2012, 5 pages. cited by
applicant.
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Primary Examiner: Nguyen; Minh Dieu
Attorney, Agent or Firm: Slater Matsil, LLP
Parent Case Text
.Iadd.More than one reissue application has been filed for the
reissue of U.S. Pat. No. 8,838,119. The reissue applications are
(1) the present application, U.S. patent application Ser. No.
15/997,317, which is an application for reissue of U.S. Pat. No.
8,838,119, and is a continuation of U.S. patent application Ser.
No. 15/261,269; (2) U.S. patent application Ser. No. 15/261,269,
which also is an application for reissue of U.S. Pat. No.
8,838,119; and (3) U.S. patent application Ser. Nos. 15/995,803,
15/996,238, 16/000,228, 15/996,239, 15/995,880, 15/996,067,
15/997,230, 15/997,280, 15/996,118, 15/996,242, and 15/996,228, all
of which are applications for reissue of U.S. Pat. No. 8,838,119,
and continuations of U.S. patent application Ser. No. 15/261,269.
.Iaddend.
Claims
What is claimed is:
.[.1. A method for adapting hyper cells in response to changing
conditions of a cellular network, the method comprising: collecting
data regarding network conditions of the cellular network, the
cellular network utilizing a wireless protocol; in accordance with
the collected data, determining that a first transmit point
associated with a second hyper cell utilizing the wireless protocol
is to be added to a first hyper cell utilizing the wireless
protocol, wherein the first hyper cell includes at least one
transmit point associated with a first cell identifier (ID); and
changing an association of the first transmit point from a second
cell ID to the first cell ID, wherein at least one transmit point
of the second hyper cell is associated with the second cell
ID..].
.[.2. The method of claim 1, wherein the network conditions include
load distribution, and wherein the method further comprises:
determining that a traffic load of a portion of the cellular
network exceeds a predetermined threshold; and changing cell IDs of
one or more transmit points transmitting to the portion of the
cellular network..].
.[.3. The method of claim 1, wherein the network conditions include
UE distribution across the network, and wherein the method further
comprises: determining that a concentration of user equipments
(UEs) serviced by the cellular network at a boundary of the first
hyper cell is above a predetermined threshold; and changing cell
IDs of one or more transmit points to the cell ID of the first
hyper cell, wherein the one or more transmit points transmit to the
boundary of the first hyper cell..].
.[.4. The method of claim 1, further comprising: determining that a
second transmit point serves less than a threshold number of UEs;
and turning off the second transmit point in response to
determining that the second transmit point is serving less than the
threshold number of UEs..].
.[.5. An apparatus for adapting hyper cells in response to changing
conditions of a cellular network, the apparatus comprising: at
least one collector configured to collect data regarding network
conditions of the cellular network, the cellular network configured
to utilize a wireless protocol; at least one processing unit
configured to: determine that a first transmit point associated
with a second hyper cell utilizing the wireless protocol is to be
added to a first hyper cell utilizing the wireless protocol in
accordance with the collected data, wherein the first hyper cell
includes at least one transmit point associated with a first cell
identifier (ID); and change an association of the first transmit
point from a second cell ID to the first cell ID, wherein at least
one transmit point of the second hyper cell is associated with the
second cell ID..].
.[.6. The apparatus of claim 5, wherein the network conditions
include load distribution, and the at least one processing unit is
configured to: determine that a traffic load of a portion of the
cellular network exceeds a predetermined threshold; and change cell
IDs of one or more transmit points transmitting to the portion of
the cellular network..].
.[.7. The apparatus of claim 5, wherein the network conditions
include user equipment (UE) distribution across the network, and
the at least one processing unit is configured to: determine that a
concentration of UEs serviced by the cellular network at a boundary
of the first hyper cell is above a predetermined threshold; and
change cell IDs of one or more transmit points to the cell ID of
the first hyper cell, wherein the one or more transmit points
transmit to the boundary of the first hyper cell..].
.[.8. The apparatus of claim 5, wherein the at least one processing
unit is configured to: determine that a second transmit point
serves less than a threshold number of UEs; and turn off the second
transmit point in response to determining that the second transmit
point is serving less than the threshold number of UEs..].
.[.9. An apparatus for adapting hyper cells in response to changing
conditions of a cellular network, the apparatus comprising: at
least one collector configured to collect data regarding network
conditions of the cellular network; at least one processing unit
configured to: determine that a transmit point is to be added to a
first hyper cell in accordance with the collected data, wherein the
first hyper cell includes at least one transmit point associated
with a first cell identifier (ID); and change an association of the
transmit point from a second cell ID to the first cell ID, wherein
at least one transmit point of a second hyper cell is associated
with the second cell ID, wherein the apparatus is a base station
controlling one or more remote radio heads and wherein the base
station is adapted to dynamically change one or more cell
identifier (ID) in response to changing network conditions,
wherein: the base station is connected to each of the one or more
remote radio heads via a communication line; and the one or more
remote radio heads are adapted to receive and transmit radio
frequency signals, and wherein the transmit point is a remote radio
head..].
.Iadd.10. A method comprising: receiving, by an apparatus, first
information over a user equipment (UE)-specific virtual dedicated
control channel transmitted from a first subset of base stations,
the first subset of base stations being from a first set of base
stations in a first hyper cell of a cellular network, wherein a
physical topology of the cellular network is disassociated with
cell identifiers (IDs), wherein the first set of base stations in
the first hyper cell have no bind with the cell IDs separately,
wherein the first set of base stations in the first hyper cell
share a first hyper cell ID, wherein the UE-specific virtual
dedicated control channel is decoded using a demodulation reference
signal (DMRS), and wherein a sequence and a location of the DMRS
are generated in accordance with an assigned UE index.
.Iaddend.
.Iadd.11. The method of claim 10, further comprising: receiving, by
the apparatus, data over a UE-specific virtual dedicated data
channel transmitted from a second subset of base stations, the
second subset of base stations being from the first set of base
stations in the first hyper cell sharing the first hyper cell ID,
the second subset of base stations being different from the first
subset of base stations, wherein the UE-specific virtual dedicated
data channel is decoded using the DMRS. .Iaddend.
.Iadd.12. The method of claim 10, wherein the cellular network
includes a supernode and a second set of base stations in a second
hyper cell, the second set of base stations associated with a
second hyper cell ID of the second hyper cell, the supernode
configured to perform operations, the operations including:
collecting data regarding network conditions of the cellular
network; and changing a first serving coverage of the first hyper
cell and a second serving coverage of the second hyper cell based
on the collected data, the changing comprising: determining that a
base station of the second set of base stations to be removed from
the second hyper cell and to be added to the first hyper cell based
on the collected data, and changing an association of the base
station from the second hyper cell ID to the first hyper cell ID
based on the determining. .Iaddend.
.Iadd.13. The method of claim 10, wherein the assigned UE index is
based on signal strength associated with the apparatus.
.Iaddend.
.Iadd.14. The method of claim 10, wherein the first subset of base
stations are transparent to the apparatus. .Iaddend.
.Iadd.15. The method of claim 10, further comprising: receiving, by
the apparatus, second information over a broadcast common control
channel transmitted from the first subset of base stations, wherein
the second information is decoded in accordance with a reference
signal tied to the first hyper cell ID. .Iaddend.
.Iadd.16. A method comprising: transmitting, by a base station to a
user equipment (UE), first information over a UE-specific virtual
dedicated control channel transmitted from a first subset of base
stations, the first subset of base stations including the base
station, the first subset of base stations being from a first set
of base stations in a first hyper cell of a cellular network,
wherein a physical topology of the cellular network is
disassociated with cell identifiers (IDs), wherein the first set of
base stations in the first hyper cell have no bind with the cell
IDs separately, wherein the first set of base stations in the first
hyper cell share a first hyper cell ID, wherein the UE-specific
virtual dedicated control channel is decoded using a demodulation
reference signal (DMRS), wherein a sequence of the DMRS is
generated in accordance with an assigned UE index, and wherein the
cellular network includes a supernode and a second set of base
stations in a second hyper cell, the second set of base stations
associated with a second hyper cell ID of the second hyper cell,
the supernode configured to perform operations, the operations
including: collecting data regarding network conditions of the
cellular network; and changing a first serving coverage of the
first hyper cell and a second serving coverage of the second hyper
cell based on the collected data, the changing comprising:
determining that a base station of the second set of base stations
to be removed from the second hyper cell and to be added to the
first hyper cell based on the collected data, and changing an
association of the base station of the second set of base stations
from the second hyper cell ID to the first hyper cell ID based on
the determining. .Iaddend.
.Iadd.17. The method of claim 16, further comprising: transmitting,
by the base station to the UE, data over a UE-specific virtual
dedicated data channel transmitted from a second subset of base
stations, the second subset of base stations being from the first
set of base stations in the first hyper cell sharing the first
hyper cell ID, the second subset of base stations being different
from the first subset of base stations, wherein the UE-specific
virtual dedicated data channel is decoded using the DMRS.
.Iaddend.
.Iadd.18. The method of claim 16, wherein the assigned UE index is
based on signal strength associated with the UE. .Iaddend.
.Iadd.19. The method of claim 16, wherein a location of the DMRS is
generated in accordance with the assigned UE index. .Iaddend.
.Iadd.20. The method of claim 16, wherein the first subset of base
stations are transparent to the UE. .Iaddend.
.Iadd.21. The method of claim 16, further comprising: transmitting,
by the base station to the UE, second information over a broadcast
common control channel transmitted from the first subset of base
stations, wherein the second information is decoded in accordance
with a reference signal tied to the first hyper cell ID.
.Iaddend.
.Iadd.22. An apparatus in a cellular network that includes a first
hyper cell, a second hyper cell, and a supernode, the apparatus
comprising: at least one processor; and a non-transitory computer
readable storage medium storing programming, the programming
including instructions when executed by the at least one processor
to: receive first information over a user equipment (UE)-specific
virtual dedicated control channel transmitted from a first subset
of base stations of a first set of base stations in the first hyper
cell of the cellular network whose physical topology is
disassociated with cell identifiers (IDs), wherein the first set of
base stations in the first hyper cell have no bind with the cell
IDs separately, wherein the first set of base stations in the first
hyper cell share a first hyper cell ID, wherein the UE-specific
virtual dedicated control channel is decoded using a demodulation
reference signal (DMRS), wherein a sequence of the DMRS is
generated in accordance with an assigned UE index, and wherein a
second set of base stations in the second hyper cell are associated
with a second hyper cell ID of the second hyper cell, the supernode
configured to perform operations, the operations including:
collecting data regarding network conditions of the cellular
network; and changing a first serving coverage of the first hyper
cell and a second serving coverage of the second hyper cell based
on the collected data, the changing comprising: determining that a
base station of the second set of base stations to be removed from
the second hyper cell and to be added to the first hyper cell based
on the collected data, and changing an association of the base
station from the second hyper cell ID to the first hyper cell ID
based on the determining. .Iaddend.
.Iadd.23. The apparatus of claim 22, the programming further
including instructions when executed by the at least one processor
to: receive data over a UE-specific virtual dedicated data channel
transmitted from a second subset of base stations, the second
subset of base stations being from the first set of base stations
in the first hyper cell sharing the first hyper cell ID, the second
subset of base stations being different from the first subset of
base stations, wherein the UE-specific virtual dedicated data
channel is decoded using the DMRS. .Iaddend.
.Iadd.24. The apparatus of claim 22, wherein the assigned UE index
is based on signal strength associated with the apparatus.
.Iaddend.
.Iadd.25. The apparatus of claim 22, wherein a location of the DMRS
is generated in accordance with the assigned UE index.
.Iaddend.
.Iadd.26. The apparatus of claim 22, wherein the first subset of
base stations are transparent to the apparatus. .Iaddend.
.Iadd.27. The apparatus of claim 22, the programming further
including instructions when executed by the at least one processor
to: receive second information over a broadcast common control
channel transmitted from the first subset of base stations, wherein
the second information is decoded in accordance with a reference
signal tied to the first hyper cell ID. .Iaddend.
.Iadd.28. A base station that is one of a first set of base
stations of a first hyper cell, the base station comprising: at
least one processor; and a non-transitory computer readable storage
medium storing programming, the programming including instructions
when executed by the at least one processor to: transmit, to a user
equipment (UE), first information over a UE-specific virtual
dedicated control channel transmitted from a first subset of base
stations of the first set of base stations in the first hyper cell
of a cellular network whose physical topology is disassociated with
cell identifiers (IDs), the first subset of base stations including
the base station, wherein the first set of base stations in the
first hyper cell have no bind with the cell IDs separately, wherein
the first set of base stations in the first hyper cell share a
first hyper cell ID, wherein the UE-specific virtual dedicated
control channel is decoded using a demodulation reference signal
(DMRS), and wherein a sequence and a location of the DMRS are
generated in accordance with an assigned UE index. .Iaddend.
.Iadd.29. The base station of claim 28, the programming further
including instructions when executed by the at least one processor
to: transmit, to the UE, data over a UE-specific virtual dedicated
data channel transmitted from a second subset of base stations, the
second subset of base stations being from the first set of base
stations in the first hyper cell sharing the first hyper cell ID,
the second subset of base stations being different from the first
subset of base stations, wherein the UE-specific virtual dedicated
data channel is decoded using the DMRS. .Iaddend.
.Iadd.30. The base station of claim 28, wherein the cellular
network includes a supernode and a second set of base stations in a
second hyper cell, the second set of base stations associated with
a second hyper cell ID of the second hyper cell, the supernode
configured to perform operations, the operations including:
collecting data regarding network conditions of the cellular
network; and changing a first serving coverage of the first hyper
cell and a second serving coverage of the second hyper cell based
on the collected data, the changing comprising: determining that a
base station of the second set of base stations to be removed from
the second hyper cell and to be added to the first hyper cell based
on the collected data, and changing an association of the base
station of the second set of base stations from the second hyper
cell ID to the first hyper cell ID based on the determining.
.Iaddend.
.Iadd.31. The base station of claim 28, wherein the assigned UE
index is based on signal strength associated with the UE.
.Iaddend.
.Iadd.32. The base station of claim 28, wherein the first subset of
base stations are transparent to the UE. .Iaddend.
.Iadd.33. The base station of claim 28, the programming further
including instructions when executed by the at least one processor
to: transmit, to the UE, second information over a broadcast common
control channel transmitted from the first subset of base stations,
wherein the second information is decoded in accordance with a
reference signal tied to the first hyper cell ID. .Iaddend.
Description
BACKGROUND
1. Field
This disclosure is generally related to improving performance of
cellular networks. More specifically, this disclosure is related to
a method and system for dynamically generating and adapting hyper
cells in response to network conditions. Various embodiments are
also related to selecting optimal transmit points for virtual
channels.
2. Related Art
In traditional cellular networks, the location of each transmit
point is carefully planned. Each transmit point creates a cell and
is assigned a unique cell identifier (ID) to define the control
channel and data channel so that simultaneous transmit point to
user equipment (UE) communications can be supported for each cell.
A single cell serves each UE, and the network maintains the
association between the cell and the UE until handover is
triggered.
As the demand on mobile broadband increases, networks are deployed
more densely and heterogeneously with a greater number of base
stations. Cells become smaller and a corresponding greater number
of cell edges are created. Cell ID assignment becomes more
difficult and the frequency of handovers increases as the UE moves
between cells. Further, the density of the cells creates much
interference between neighboring cells.
In one approach, LTE Coordinated Multipoint (CoMP) scenario 4
specifies that one or more remote radio heads (RRHs) share a same
cell ID as a macro cell to which the RRHs are connected. However,
LTE CoMP scenario 4 (available at
http://www.3gpp.org/ftp/Specs/html-info/36819.htm) only allows
fixed sharing of a single cell ID between a macro cell and all RRHs
controlled by it. There is handover and changing of the cell ID
when the user moves away from the macro cell and the connected
RRHs. Such an approach is insufficient for addressing the problems
of interference, complex cell ID assignment, and frequent
handovers.
SUMMARY
One embodiment of the present invention provides a system for
adapting hyper cells in response to changing conditions of a
cellular network. During operation, the system collects data
regarding network conditions of the cellular network; in accordance
with the collected data, determines that a transmit point is to be
added to a first hyper cell, wherein the first hyper cell includes
at least one transmit point associated with a first cell identifier
(ID); and changes an association of the transmit point from a
second cell ID to the first cell ID, wherein at least one transmit
point of a second hyper cell is associated with the second cell
ID.
Another embodiment of the present invention provides a system for
transmitting virtual channels in a cellular network. The system
includes a virtual channel transmission mechanism configured to
select one or more transmit points from a set of transmit points to
transmit a virtual dedicated control channel and/or a virtual data
channel to a serviced UE, wherein the one or more transmit points
share a common cell ID; and wherein one or more transmission
schemes of the virtual data channel and virtual dedicated control
channel, including scrambling, pilot design, and/or pilot sequence
and location, are created in accordance with a UE ID.
A further embodiment of the present invention provides a method for
transmitting virtual channels in a cellular network. The method
includes selecting one or more transmit points from a set of
transmit points to transmit a virtual dedicated control channel
and/or a virtual data channel to a serviced user equipment (UE),
wherein the one or more transmit points share a common cell ID; and
wherein one or more transmission schemes of the virtual data
channel and virtual dedicated control channel, including
scrambling, pilot design, and/or pilot sequence and location, are
created in accordance with a UE ID.
A further embodiment of the present invention provides a method for
adapting hyper cells in response to changing conditions of a
cellular network. The method includes collecting data regarding
network conditions of the cellular network; in accordance with the
collected data, determining that a transmit point is to be added to
a first hyper cell, wherein the first hyper cell includes at least
one transmit point associated with a first cell ID; and changing an
association of the transmit point from a second cell ID to the
first cell ID, wherein at least one transmit point of a second
hyper cell is associated with the second cell ID.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1A illustrates an exemplary CRAN communication system from
which hyper cells may be generated, in accordance with an
embodiment of the present invention.
FIG. 1B illustrates two hyper cells with a shared transmit point,
in accordance with an embodiment of the present invention.
FIG. 2 presents a diagram illustrating an example of how to create
hyper cells in a CRAN cluster, in accordance with an embodiment of
the present invention.
FIG. 3 presents a diagram of an example hyper cell with multiple
virtual data channels, in accordance with an embodiment of the
present invention.
FIG. 4 presents a diagram illustrating an exemplary downlink (DL)
control channel design, in accordance with an embodiment of the
present invention.
FIG. 5 and FIG. 6 each present a flow chart illustrating a process
of selecting transmit points for a virtual data channel and/or a
virtual dedicated control channel, in accordance with an embodiment
of the present invention.
FIG. 7 illustrates an exemplary computing system for enabling
dynamic hyper cell configuration, in accordance with an embodiment
of the present invention.
In the figures, like reference numerals refer to the same figure
elements.
DETAILED DESCRIPTION
The following description is presented to enable any person skilled
in the art to make and use the embodiments, and is provided in the
context of a particular application and its requirements. Various
modifications to the disclosed embodiments will be readily apparent
to those skilled in the art, and the general principles defined
herein may be applied to other embodiments and applications without
departing from the spirit and scope of the present disclosure.
Thus, the present invention is not limited to the embodiments
shown, but is to be accorded the widest scope consistent with the
principles and features disclosed herein.
Overview
Embodiments of the present invention solve the problems of
excessive interference and management overhead in cellular networks
by introducing the concept of "hyper cell" and dynamically managing
hyper cells to eliminate cell edge UEs and optimally selecting
transmit points for UEs. A hyper cell is a virtual entity for
dynamical coordination of data and control signaling transmission.
It is a logic cell and the coverage of the hyper cell can change
depending on the hyper cell's association to the physical transmit
point(s). From the perspective of network, a hyper cell includes a
group of transmit points which have relatively strong interference
and are connected via high capacity backhaul. From the perspective
of a UE, a hyper cell is an area covered by a virtual access
entity.
A dynamic cell configuration system disassociates the concept of
cell IDs from the physical topology of the cellular network, which
facilitates greater flexibility and efficiency in network
management. By breaking the bind between the cell ID and the
physical transmitter, the system can generate hyper cells that
include multiple transmit points having the same cell ID. The
system adapts the hyper cells according to network topology, load
distribution, and UE distribution. This reduces the frequency of
handovers and amount of interference. The system can also share
transmit points between multiple hyper cells by switching the
transmit point between the hyper cells. This hyper cell
configuration reduces the number of cell edge UEs, reduces
interference, and improves the UE transition between hyper cells.
The system can further select optimal transmit points within the
hyper cells to boost the capacity of virtual channels. In addition,
the virtual control channels and virtual data channel can be
de-coupled for optimal performance.
Network Environment
A cloud radio access network (CRAN) cluster consolidates all basic
processing power of a cellular network. The CRAN manages a group of
transmit points that are connected together with a high-speed
backhaul network. A CRAN central processing unit performs the
processing for the multiple transmit points. This brings the
network intelligence into the cloud, leaving only the radios and
antennas at the transmission site. By centralizing all the active
electronics of multiple cell sites at one location, the operating
costs are minimized.
In one embodiment, in a CRAN cluster, a supernode generates a hyper
cell by assigning the same cell ID to one or more transmit point(s)
which have the strongest mutual inter-cell interference. The
supernode may estimate inter-cell interference based on UE reports
or the measurement at transmit points. A supernode can be a base
station, computing station, or controller configured to generate
and manage hyper cells. The supernode can manage baseband signal
processing of all transmit points controlled by the supernode. In
some implementations, the supernode can also be responsible for
only part of signal processing, depending on backhaul
capability.
The cell ID is a logical assignment to all physical transmit points
of the hyper cell. The hyper cell may be dynamically configured.
Unlike traditional cellular networks, there is no fixed one-to-one
mapping relation between a transmit point and a cell ID. The area
served by the hyper cell is amorphous and the system dynamically
adds/removes transmit points to/from the hyper cell.
In one embodiment, the system supports overlapped hyper cells where
a transmit point can be logically associated with different hyper
cells. For the transmitters that are physically located at the
boundary of hyper cells, logically the network associates the
transmit point with different hyper cells at different points in
time, frequency, or space. The hyper cells may share the resources
of the transmit point. A shared transmit point can reduce
interference for UEs located at the boundary between the two
sharing hyper cells. UEs that are located near the boundaries of
two hyper cells experience less handovers because the shared
transmit point is associated with either hyper cell at different
times, frequencies or spatial directions. Further, as a UE moves
between the two hyper cells, the transition is a smoother
experience for the user. In one embodiment, the network changes the
cell ID of the transmit point to transition a user moving between
hyper cells.
Embodiments of the present invention also facilitate virtual
channels which allow for greater scheduling flexibility, increased
data and control channel capacity, energy savings, and improved
mobility management. Subsequent sections of this disclosure discuss
five aspects of virtual channels and/or hyper cells in greater
detail. These five aspects are: virtual data channels, broadcast
common control channel and virtual dedicated control channel,
transmit point optimization, UE-centric channel sounding and
measurement, and single frequency network (SFN) synchronization.
The virtual data channel, broadcast common control channel, virtual
dedicated control channel, and/or synchronization channel can also
be implemented separate from the hyper cells.
In one embodiment, the supernode is a part of a system that manages
all aspects of hyper cells and virtual channels. The system can
also include a hyper transceiver to enable joint scheduling and
joint transmission for a hyper cell. Each hyper cell supports a
single centralized data plane and a single centralized control
plane. In one embodiment, a CRAN sub-cluster supernode or CRAN
cluster supernode generates the virtual data channels, broadcast
common control channel and virtual dedicated control channels of
the hyper cell.
CRAN Communication System
FIG. 1A illustrates an exemplary CRAN communication system 100 from
which hyper cells may be generated, in accordance with an
embodiment of the present invention. Generally, the system 100
enables multiple wireless users to transmit and receive data and
other content. The system 100 may implement one or more channel
access methods, such as code division multiple access (CDMA), time
division multiple access (TDMA), frequency division multiple access
(FDMA), orthogonal FDMA (OFDMA), or single-carrier FDMA (SC-FDMA).
Although FIG. 1A illustrates an example architecture for hyper
cells, embodiments of the invention are not limited to a particular
architecture. Other network architectures for hyper cells are also
possible. For example, any network architecture where transmit
points in the network are controlled by one or more supernodes with
centralized signal processing capability can also work with hyper
cells.
In this example, communication system 100 includes user equipment
(UE) 110a-110c, transmit points 130a-130b, two access units
170a-170b, a core network 132, a public switched telephone network
(PSTN) 140, the Internet 150, and other networks 160. While certain
numbers of these components or elements are shown in FIG. 1A, any
number of these components or elements may be included in the
system 100.
The UEs 110a-110c are configured to operate and/or communicate in
the system 100. For example, the UEs 110a-110c are configured to
transmit and/or receive wireless signals. Each UE 110a-110c
represents any suitable end user device and may include such
devices (or may be referred to) as a user device, wireless
transmit/receive unit (WTRU), mobile station, fixed or mobile
subscriber unit, pager, cellular telephone, personal digital
assistant (PDA), smartphone, laptop, computer, touchpad, wireless
sensor, or consumer electronics device.
Access units 170a, 170b can each be a base station controlling
transmitters or a controller controlling multiple base stations. A
base station can control multiple transmitters. Transmit points
130a, 130b can be any type of transmitter. The transmitters can be,
for example, mobile-relay station, base station transmitter, pico
transmitter, or femto transmitter. The transmitters can be remote
radio heads (RRHs) in some implementations. The transmit points can
also be base stations controlled by a controller. In some
embodiments, multiple-input multiple-output (MIMO) technology may
be employed having multiple transceivers for each cell.
Each access unit 170a-170b is configured to wirelessly interface
with one or more of the UEs 110a-110c to enable access to the core
network 132, the PSTN 140, the Internet 150, and/or the other
networks 160. In various embodiments, the access units 170a-170b
(or transmit points 130a, 130b) may also include (or be) one or
more of several well-known devices, such as a base transceiver
station (BTS), a Node-B (NodeB), an evolved NodeB (eNodeB), a Home
NodeB, a Home eNodeB, a site controller, an access point (AP), or a
wireless router. One or more Node-B may be controlled by radio
network controllers.
In an embodiment, CRAN systems can include a base station or a
centralized node controlling one or more RRHs. Base stations can
implement MAC/PHY and antenna array system (AAS) functionality.
Each base station operates to transmit and/or receive wireless
signals within a particular geographic region or area. For example,
access units 170a-170b can be base stations and, through remote
radio heads, may communicate with one or more of the UEs 110a-110c
over one or more air interfaces using wireless communication links.
The air interfaces may utilize any suitable radio access
technology.
A RRH contains the radio frequency circuitry plus
analog-to-digital/digital-to-analog converters and up/down
converters. The RRHs are located between a base station and the
UEs, and are connected to a base station using optical fiber or any
other communication line. The RRHs receive and convert digital
signals to analog, then amplifies the power and sends the radio
frequency signals.
It is contemplated that the system 100 may use multiple channel
access functionality, including such schemes as described above. In
particular embodiments, the base stations and UEs implement LTE,
LTE-A, and/or LTE-B. Of course, other multiple access schemes and
wireless protocols may be utilized.
Each of the access units 170a, 170b are in communication with the
core network 132 to provide the UEs 110a-110c with voice, data,
application, Voice over Internet Protocol (VoIP), or other
services. The access units and/or the core network 132 may be in
direct or indirect communication with one or more other access
units (not shown). The core network 132 may also serve as a gateway
access for other networks (such as PSTN 140, Internet 150, and
other networks 160). In addition, some or all of the UEs 110a-110c
may include functionality for communicating with different wireless
networks over different wireless links using different wireless
technologies and/or protocols.
Each of the example transmit points 130a-130b, or any combination
of the illustrated transmit points, may be assigned a common cell
ID and form a hyper cell. Hyper cells are discussed in greater
detail with respect to FIG. 1B.
Although FIG. 1A illustrates one example of a CRAN communication
system 100 from which hyper cells may be generated, various changes
may be made to FIG. 1A. For example, CRAN communication system 100
could include any number of UEs, base stations, supernodes,
networks, or other components in any suitable configuration. Also,
the techniques described herein can be used in any other suitable
system.
Hyper Cell Examples
FIG. 1B illustrates two hyper cells with a shared transmit point,
in accordance with an embodiment of the present invention. Hyper
cells 182, 184 each includes many transmit points that are assigned
the same logical cell ID. For example, hyper cell 182 includes
transmit points 186, 187, 188, 189, 190, and 192. Transmit points
190, 192 communicates with UE 194. Transmit point 196 is assigned
to hyper cells 182, 184 at different times, frequencies or spatial
directions and the system switches the logical cell ID for transmit
point 196 between the two hyper cells.
In one embodiment, a system dynamically updates the hyper cell
topology to adapt to changes in network topology, load
distribution, and/or UE distribution. The system may include a data
collector to collect data regarding network conditions of the
cellular network. If the concentration of UEs increases in one
region, the system may dynamically expand the hyper cell to include
transmit points near the higher concentration of UEs. For example,
the system may expand hyper cell 182 to include other transmit
points if the concentration of UEs located at the edge of the hyper
cell increases above a certain threshold. As another example, the
system may expand hyper cell 182 to include a greater concentration
of UEs located between two hyper cells. Also, if the traffic load
increases significantly at one region, the system may also expand
the hyper cell to include transmit points near the increased
traffic load. For example, if the traffic load of a portion of the
network exceeds a predetermined threshold, the system may change
the cell IDs of one or more transmit points that are transmitting
to the impacted portion of the cellular network.
Further, the system may change the cell ID associated with transmit
point 196 from the cell ID of hyper cell 182 to the cell ID of
hyper cell 184. In one implementation, the system can change the
association of a transmit point with different hyper cells every 1
millisecond. With such a flexible cell formation mechanism, all UEs
can be served by the best transmit points so that virtually there
are no cell edge UEs.
In one embodiment, the system may also save power by turning off
silent transmit points (e.g., any transmit point other than
transmit points 190, 192) if there are no UEs to service for those
silent transmit points. The system can also save power by turning
off transmit points according to some criteria (e.g., turn off
those that are serving less than a threshold number of UEs).
FIG. 2 presents a diagram illustrating an example of how to create
hyper cells in a CRAN cluster, in accordance with an embodiment of
the present invention. A CRAN cluster 202 includes a number of
individual cells, such as cell 204. Without hyper cells, the CRAN
network can only assign each transmit point a unique cell ID to
form the individual cells. To create a hyper cell, the system
assigns a common cell ID to all the cells of the CRAN cluster that
form the hyper cell. In one embodiment, the network may create
multiple hyper cells within a CRAN cluster. Each hyper cell has a
unique cell ID.
FIG. 2 also illustrates exemplary optimal transmit points for
facilitating a virtual data channel and virtual dedicated control
channel for UE 206. The three transmit points 208, 210, and 212 are
optimally situated to transmit the virtual channels to UE 206. The
three transmit points form a virtual transmit point. The system can
dynamically combine multiple physical transmitters to form a
virtual transmit point. From the perspective of a UE, the virtual
transmit points appear to be a single transmitter. The system can
create many virtual transmit points for a hyper cell and coordinate
their transmissions. The system can dynamically change the physical
transmitters that make up the hyper cell. Determining optimal
transmit points is further discussed with respect to FIG. 5 and
FIG. 6.
Virtual Data Channels
FIG. 3 presents a diagram of an example hyper cell with multiple
virtual data channels, in accordance with an embodiment of the
present invention. The system can support multiple parallel data
channels within a single hyper cell, each serving a different UE.
In other words, each virtual data channel is UE-specific. The hyper
cell may have multiple different physical transmit points
transmitting to create the virtual data channels. The actual
physical transmit points of the virtual data channels are also
UE-specific and are transparent to each UE. A UE distinguishes
virtual data channel signals by examining the UE ID associated with
each transmission. The data transmission schemes, including data
scrambling, pilot design, and pilot sequence and location, are all
created in accordance with the UE ID.
As the UEs move to different locations, the system dynamically
assigns different physical transmit points to service the UEs. The
physical transmit points form the virtual data channels for the
respective serviced UEs. Note that the cell ID transmitted from the
different physical transmit points belonging to the same hyper cell
remains the same. As illustrated in FIG. 3, an example hyper cell
300 has three virtual data channels, one for each UE. Three
transmit points 302, 304, 306 provide a virtual data channel for UE
307, two transmit points 302, 304 provide a virtual data channel
for UE 309, and two transmit points 308, 310 provide a virtual data
channel for UE 311. Transmit points 312, 314 are silent and may be
turned off to save energy. The description associated with FIG. 5
and FIG. 6 discusses additional details of various embodiments for
optimally selecting transmit points.
In one embodiment, with the CRAN framework, the supernode controls
the generation of the virtual data channels based on load balancing
and UE distribution within a CRAN cluster. A CRAN cluster can
support multiple parallel virtual data channels.
Broadcast Common Control Channel/Virtual Dedicated Control
Channel
FIG. 4 presents a diagram illustrating an exemplary downlink (DL)
control channel design, in accordance with an embodiment of the
present invention. The system provides for a broadcast common
control channel and a virtual dedicated control channel. A
broadcast common control channel 402 carries common system
configuration information transmitted by all or partial transmit
points sharing the same cell ID. Every UE can decode information
from the broadcast common control channel 402 in accordance with a
common reference signal (CRS). The CRS sequence and location are
tied to the cell ID of the hyper cell.
A virtual dedicated control channel 404 carries UE-specific control
information (e.g., DL scheduling, uplink (UL) grant). Each of UEs
406, 408 has a subset of transmit points surrounding the UE. The
transmit points transmit the UE-specific virtual dedicated control
channels 410, 412. Virtual dedicated control channel 410 is
specific to UE 406, and virtual dedicated control channel 412 is
specific to UE 408. In some embodiments, one or more transmission
schemes of the virtual data channel and/or the virtual dedicated
control channel, including scrambling, pilot design, and/or pilot
sequence and location, are created in accordance with a UE ID.
Further, a hyper cell ID can be applied together with the UE ID to
differentiate transmission of the virtual data channel and/or
virtual control channel from different hyper cells.
Parallel virtual dedicated control channels can be provided in each
hyper cell. The demodulation of each virtual dedicated control
channel is performed in accordance with a UE-specific reference
signal (RS), the sequence and location of which are linked to the
UE ID. To distinguish the virtual dedicated control channels
communicated from different hyper cells, the sequence of
UE-specific RS is covered by a sequence specific to each hyper
cell.
The system may apply transmit point selection techniques and
transmit power control techniques to minimize intra-hyper cell
interference and inter-hyper cell interference. The selected
transmit points are transparent to the UEs. In one embodiment, for
a UE with a poor Signal to Interference plus Noise Ratio (SINR),
the system can transmit the virtual dedicated control channel
and/or virtual data channel from multiple transmit points to
improve signal quality. In addition, the system may apply Transmit
Time Interval (TTI) bundling to a fixed or slow moving UE in order
to further enhance the capacity of the UE-specific virtual
dedicated control channel.
Selecting Transmit Points for Virtual Channels
FIG. 5 and FIG. 6 each present a flow chart illustrating a process
of selecting transmit points for a virtual data channel and/or a
virtual dedicated control channel, in accordance with an embodiment
of the present invention. A virtual channel transmission mechanism
can be configured to select one or more transmit points from a set
of transmit points to transmit a virtual dedicated control channel
and/or a virtual data channel to a serviced UE. For each UE, there
are two techniques for selecting the optimal transmit points for
the virtual data channel and the virtual dedicated control channel.
The selection processes attempt to maximize the capacity of the
UE-specific virtual dedicated control channel and virtual data
channel. FIG. 5 presents a UE-centric technique for selecting the
transmit points. FIG. 6 presents a network-centric technique for
selecting the transmit points. The transmit points for a virtual
data channel can be different from the transmit points for a
virtual dedicated control channel, for the same UE. The selected
transmit points are transparent to the UE.
During operation of the technique illustrated in FIG. 5, each of
the transmit points sends a DL sounding reference signal (SRS)
(operation 502) as a training sequence. In one embodiment,
different transmit points transmit the DL SRS at different
frequencies or at different times. After receiving the DL SRS, the
UE measures the signal strength of each DL SRS (operation 504). The
UE reports the measurement results to the supernode (operation
506). The supernode generates a table with a UE index and
corresponding potential transmit points (operation 508). The
supernode selects the best transmit points to all served UEs based
on the table and the status of network load distribution and UE
distribution (operation 510). In one embodiment, the supernode
compares the reported measurement results to previous DL SRS
transmissions to determine the best transmit points for each of the
UEs.
During operation of the technique illustrated in FIG. 6, each
transmit point detects a UL transmission from a UE within the
transmit point's coverage range. The transmissions may be for any
data, including any one of a sounding channel, control channel
and/or data channel data (operation 602). The transmit points
measure the strength of the UE signals. The transmit point may
filter UEs with insufficient signal strength (operation 604). Each
transmit point reports measurements of the detected UL
transmissions to the supernode (operation 606). The supernode
generates a table with the UE index and corresponding potential
transmit points (operation 608). In one embodiment, the supernode
populates the table with UEs and the strength of signals received
by the transmit points. The supernode selects the optimal transmit
points for all served UEs based on the generated table and on the
status of network load and UE distribution (operation 610).
In one embodiment, to maintain the transparency of the transmit
points in each hyper cell, demodulation of the virtual channels is
not tied to the transmit points. In one implementation, the system
uses the UE ID to bootstrap all communications between the UE and
the transmit points. The system distinguishes between the
transmission signals of different UEs with a UE-centric reference
signal. The system uses a UE-centric demodulation reference signal
(DMRS) to decode the virtual dedicated data channel and the virtual
dedicated control channel. The system defines the sequence and
location of the UE-centric DMRS with the UE index. The system
automatically generates each UE index from a respective UE ID or
assigns the UE index. Each UE has a unique UE index.
Each hyper cell is associated with a synchronization channel. All
or a portion of transmit points in a hyper cell can transmit the
synchronization channel. In one embodiment, a transmit point
belonging to multiple hyper cells does not transmit the
synchronization channel. In another embodiment, frequency division
multiplexing (FDM), code division multiplexing (CDM), or time
division multiplexing (TDM) can be applied to enable
synchronization channel transmission for transmit points associated
with multiple hyper cells.
FIG. 7 illustrates an exemplary computing system for enabling
dynamic hyper cell configuration, in accordance with an embodiment
of the present invention. In one embodiment, a computing and
communication system 700 includes a processor 702, a memory 704,
and a storage device 706. Storage device 706 stores a dynamic hyper
cell configuration application 708, as well as other applications,
such as applications 710 and 712. During operation, application 708
is loaded from storage device 706 into memory 704 and then executed
by processor 702. While executing the program, processor 702
performs the aforementioned functions. Computing and communication
system 700 is coupled to an optional display 714, keyboard 716, and
pointing device 718.
The data structures and code described in this detailed description
are typically stored on a machine-readable storage medium, which
may be any device or medium that can store code and/or data for use
by a computing system. The machine-readable storage medium
includes, but is not limited to, volatile memory, non-volatile
memory, magnetic and optical storage devices such as disk drives,
magnetic tape, CDs (compact discs), DVDs (digital versatile discs
or digital video discs), or other media capable of storing
machine-readable media now known or later developed.
The methods and processes described in the detailed description
section can be embodied as code and/or data, which can be stored in
a machine-readable storage medium as described above. When a
computing system reads and executes the code and/or data stored on
the machine-readable storage medium, the computing system performs
the methods and processes embodied as data structures and code and
stored within the machine-readable storage medium.
Furthermore, methods and processes described herein can be included
in hardware modules or apparatus. These modules or apparatus may
include, but are not limited to, an application-specific integrated
circuit (ASIC) chip, a field-programmable gate array (FPGA), a
dedicated or shared processor that executes a particular software
module or a piece of code at a particular time, and/or other
programmable-logic devices now known or later developed. When the
hardware modules or apparatus are activated, they perform the
methods and processes included within them. Such modules or
apparatuses may form part of base stations or supernode machines
that manage and enable hyper cells and/or virtual channels or other
various features described herein.
.Iadd.An embodiment method for adapting hyper cells in response to
changing conditions of a cellular network comprises collecting data
regarding network conditions of the cellular network; in accordance
with the collected data, determining that a transmit point is to be
added to a first hyper cell, wherein the first hyper cell includes
at least one transmit point associated with a first cell identifier
(ID); and changing an association of the transmit point from a
second cell ID to the first cell ID, wherein at least one transmit
point of a second hyper cell is associated with the second cell ID.
.Iaddend.
.Iadd.Optionally, in the embodiment method, the network conditions
include load distribution, and the method further comprises
determining that a traffic load of a portion of the cellular
network exceeds a predetermined threshold; and changing cell IDs of
one or more transmit points transmitting to the portion of the
cellular network. .Iaddend.
.Iadd.Optionally, in the embodiment method, the network conditions
include UE distribution across the network, and the method further
comprises determining that a concentration of user equipments (UEs)
serviced by the cellular network at a boundary of the first hyper
cell is above a predetermined threshold; and changing cell IDs of
one or more transmit points to the cell ID of the first hyper cell,
wherein the one or more transmit points transmit to the boundary of
the first hyper cell. .Iaddend.
.Iadd.Optionally, the embodiment method further comprises
determining that a second transmit point serves less than a
threshold number of UEs; and turning off the second transmit point
in response to determining that the second transmit point is
serving less than the threshold number of UEs. .Iaddend.
.Iadd.An embodiment apparatus for adapting hyper cells in response
to changing conditions of a cellular network comprises at least one
collector configured to collect data regarding network conditions
of the cellular network; at least one processing unit configured
to: determine that a transmit point is to be added to a first hyper
cell in accordance with the collected data, wherein the first hyper
cell includes at least one transmit point associated with a first
cell identifier (ID); and change an association of the transmit
point from a second cell ID to the first cell ID, wherein at least
one transmit point of a second hyper cell is associated with the
second cell ID. .Iaddend.
.Iadd.Optionally, in the embodiment apparatus, the network
conditions include load distribution, and the at least one
processing unit is configured to determine that a traffic load of a
portion of the cellular network exceeds a predetermined threshold;
and change cell IDs of one or more transmit points transmitting to
the portion of the cellular network. .Iaddend.
.Iadd.Optionally, in the embodiment apparatus the network
conditions include user equipment (UE) distribution across the
network, and the at least one processing unit is configured to
determine that a concentration of UEs serviced by the cellular
network at a boundary of the first hyper cell is above a
predetermined threshold; and change cell IDs of one or more
transmit points to the cell ID of the first hyper cell, wherein the
one or more transmit points transmit to the boundary of the first
hyper cell. .Iaddend.
.Iadd.Optionally, in the embodiment apparatus the at least one
processing unit is configured to determine that a second transmit
point serves less than a threshold number of UEs; and turn off the
second transmit point in response to determining that the second
transmit point is serving less than the threshold number of UEs.
.Iaddend.
.Iadd.Optionally, in the embodiment apparatus the apparatus is a
base station controlling one or more remote radio heads and the
base station is adapted to dynamically change one or more cell
identifier (ID) in response to changing network conditions, wherein
the base station is connected to each of the one or more remote
radio heads via a communication line; the one or more remote radio
heads are adapted to receive and transmit radio frequency signals;
the base station includes a data collector configured to collect
data regarding network conditions of the cellular network; and the
base station includes at least one processing unit configured to
determine that a transmit point is to be added to a first hyper
cell in accordance with the collected data, wherein the first hyper
cell includes at least one transmit point associated with a first
cell ID; and change an association of the transmit point from a
second cell ID to the first cell ID, wherein at least one transmit
point of a second hyper cell is associated with the second cell ID,
and wherein the transmit point is a remote radio head.
.Iaddend.
Although the present invention has been described with reference to
specific features and embodiments thereof, it is evident that
various modifications and combinations can be made thereto without
departing from the spirit and scope of the invention. The
specification and drawings are, accordingly, to be regarded simply
as an illustration of the invention as defined by the appended
claims, and are contemplated to cover any and all modifications,
variations, combinations or equivalents that fall within the scope
of the present invention.
* * * * *
References