U.S. patent application number 14/726265 was filed with the patent office on 2015-12-10 for mbms coexistence in a network with multiple types of base stations.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Jun WANG, Xiaoxia ZHANG.
Application Number | 20150358940 14/726265 |
Document ID | / |
Family ID | 53433283 |
Filed Date | 2015-12-10 |
United States Patent
Application |
20150358940 |
Kind Code |
A1 |
ZHANG; Xiaoxia ; et
al. |
December 10, 2015 |
MBMS COEXISTENCE IN A NETWORK WITH MULTIPLE TYPES OF BASE
STATIONS
Abstract
A method, an apparatus, and a computer program product for
wireless communication are provided. The apparatus may be a femto
cell. The apparatus determines MBSFN subframes at a frequency of a
first base station. The first base station has a first power class,
the apparatus has a second power class lower than the first power
class. The apparatus determines, in the MBSFN subframes, a first
set of symbols used for control information and a second set of
symbols used for MBSFN signals by the first base station. The
apparatus transmits, at the frequency, unicast control information
in a subset of the first set of symbols. The apparatus transmits,
at the frequency, unicast data with a reduced power in the second
set of symbols.
Inventors: |
ZHANG; Xiaoxia; (San Diego,
CA) ; WANG; Jun; (Poway, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
53433283 |
Appl. No.: |
14/726265 |
Filed: |
May 29, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62008454 |
Jun 5, 2014 |
|
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|
Current U.S.
Class: |
370/312 |
Current CPC
Class: |
H04W 88/08 20130101;
H04W 8/005 20130101; H04W 52/281 20130101; G06Q 20/3226 20130101;
H04W 64/00 20130101; H04W 4/02 20130101; H04W 72/005 20130101; H04W
72/1257 20130101; H04W 4/023 20130101; G06Q 20/405 20130101; H04L
5/0053 20130101; H04W 84/045 20130101; H04W 84/12 20130101; H04W
4/06 20130101 |
International
Class: |
H04W 72/00 20060101
H04W072/00; H04W 4/06 20060101 H04W004/06 |
Claims
1. A method of wireless communication of a second base station,
comprising: determining multicast broadcast single frequency
network (MBSFN) subframes used by a first base station at a
frequency, the first base station having a first power class, the
second base station having a second power class lower than the
first power class; determining, in the MBSFN subframes, a first set
of symbols used for control information by the first base station
and a second set of symbols used for MBSFN signals by the first
base station; transmitting, at the frequency, unicast control
information in a subset of the first set of symbols; and
transmitting, at the frequency, unicast data with a reduced power
in the second set of symbols.
2. The method of claim 1, further comprising transmitting, at the
frequency, a system information block (SIB) 13 in non-MBSFN
subframes and a multicast control channel (MCCH) change
notification in the first set of symbols.
3. The method of claim 2, further comprising: determining resources
within the second set of symbols used by the first base station for
transmitting a multicast control channel (MCCH); and transmitting,
synchronously with the first base station at the frequency, the
MCCH in the second set of symbols within the determined
resources.
4. The method of claim 3, further comprising: determining
additional resources within the second set of symbols used by the
first base station for transmitting a multicast traffic channel
(MTCH); and transmitting, synchronously with the first base station
at the frequency, the MTCH in the second set of symbols within the
determined additional resources.
5. The method of claim 4, wherein the second base station has an M1
interface with a multimedia broadcast multicast service (MBMS)
gateway and an M2 interface with a multicast coordination entity
(MCE), the method further comprising joining an MBMS session
associated with a broadcast multicast service center (BM-SC).
6. The method of claim 4, wherein the second base station has an M1
interface with a multimedia broadcast multicast service (MBMS)
gateway, the method further comprising: receiving user service
description (USD) bootstrapping information; obtaining a USD based
on the USD bootstrapping information; and obtaining a multicast
Internet Protocol (IP) address and a source IP address from the
USD, wherein the SIB 13, the MCCH change notification, the MCCH,
and the MTCH are based on the obtained multicast IP address and the
obtained source IP address.
7. The method of claim 4, wherein the second base station has an M1
interface with a multimedia broadcast multicast service (MBMS)
gateway and an M2 interface with a multicast coordination entity
(MCE), the method further comprising: sending an MBMS session start
initiation to a broadcast multicast service center (BM-SC) through
the MCE, a mobility management entity (MME), and the MBMS gateway
to initiate an MBMS session with the BM-SC.
8. The method of claim 1, further comprising receiving information
from a home evolved node B (eNB) (HeNB) management system (HMS),
wherein the MBSFN subframes of the first base station are
determined based on the information received from the HMS.
9. The method of claim 8, wherein the information from the HMS
indicates an MBSFN configuration, and the method further comprises
transmitting, based on the MBSFN configuration, at least one of a
system information block (SIB) 13, a multicast control channel
(MCCH) change notification, an MCCH synchronously with the first
base station at the frequency, or a multicast traffic channel
(MTCH) synchronously with the first base station at the
frequency.
10. The method of claim 1, further comprising receiving a system
information block (SIB) 2 from the first base station, wherein the
MBSFN subframes are determined based on the received SIB 2.
11. The method of claim 1, further comprising: receiving a system
information block (SIB) 13 from the first base station; obtaining
an MBSFN configuration based on the received SIB 13; and
transmitting, at the frequency, the SIB 13 and a multicast control
channel (MCCH) change notification based on the MBSFN
configuration.
12. The method of claim 1, further comprising receiving multicast
channel (MCH) scheduling information (MSI), wherein the MBSFN
subframes are further determined based on the received MSI.
13. The method of claim 12, further comprising: receiving a system
information block (SIB) 13 from the first base station; obtaining a
multicast control channel (MCCH) from the first base station based
on the received SIB 13; obtaining an MBSFN configuration based on
the obtained MCCH and the SIB 13; and transmitting, at the
frequency, the SIB 13, an MCCH change notification, and the MCCH
based on the MBSFN configuration, wherein the MCCH is transmitted
synchronously with the first base station at the frequency.
14. An apparatus of wireless communication comprising: means for
determining multicast broadcast single frequency network (MBSFN)
subframes used by a first base station at a frequency, the first
base station having a first power class, the apparatus having a
second power class lower than the first power class; means for
determining, in the MBSFN subframes, a first set of symbols used
for control information by the first base station and a second set
of symbols used for MBSFN signals by the first base station; means
for transmitting, at the frequency, unicast control information in
a subset of the first set of symbols; and means for transmitting,
at the frequency, unicast data with a reduced power in the second
set of symbols.
15. The apparatus of claim 14, further comprising means for
transmitting, at the frequency, a system information block (SIB) 13
in non-MBSFN subframes and a multicast control channel (MCCH)
change notification in the first set of symbols.
16. The apparatus of claim 15, further comprising: means for
determining resources within the second set of symbols used by the
first base station for transmitting a multicast control channel
(MCCH); and means for transmitting, synchronously with the first
base station at the frequency, the MCCH in the second set of
symbols within the determined resources.
17. An apparatus for wireless communication, comprising: a memory;
and at least one processor coupled to the memory and configured to:
determine multicast broadcast single frequency network (MBSFN)
subframes used by a first base station at a frequency, the first
base station having a first power class, the apparatus having a
second power class lower than the first power class; determine, in
the MBSFN subframes, a first set of symbols used for control
information by the first base station and a second set of symbols
used for MBSFN signals by the first base station; transmit, at the
frequency, unicast control information in a subset of the first set
of symbols; and transmit, at the frequency, unicast data with a
reduced power in the second set of symbols.
18. The apparatus of claim 17, wherein the at least one processor
is further configured to transmit, at the frequency, a system
information block (SIB) 13 in non-MBSFN subframes and a multicast
control channel (MCCH) change notification in the first set of
symbols.
19. The apparatus of claim 18, wherein the at least one processor
is further configured to: determine resources within the second set
of symbols used by the first base station for transmitting a
multicast control channel (MCCH); and transmit, synchronously with
the first base station at the frequency, the MCCH in the second set
of symbols within the determined resources.
20. The apparatus of claim 19, wherein the at least one processor
is further configured to: determine additional resources within the
second set of symbols used by the first base station for
transmitting a multicast traffic channel (MTCH); and transmit,
synchronously with the first base station at the frequency, the
MTCH in the second set of symbols within the determined additional
resources.
21. The apparatus of claim 20, wherein the apparatus has an M1
interface with a multimedia broadcast multicast service (MBMS)
gateway and an M2 interface with a multicast coordination entity
(MCE), and wherein the at least one processor is further configured
to join an MBMS session associated with a broadcast multicast
service center (BM-SC).
22. The apparatus of claim 20, wherein the apparatus has an M1
interface with a multimedia broadcast multicast service (MBMS)
gateway, and wherein the at least one processor is further
configured to: receive user service description (USD) bootstrapping
information; obtain a USD based on the USD bootstrapping
information; and obtain a multicast Internet Protocol (IP) address
and a source IP address from the USD, wherein the SIB 13, the MCCH
change notification, the MCCH, and the MTCH are based on the
obtained multicast IP address and the obtained source IP
address.
23. The apparatus of claim 20, wherein the apparatus has an M1
interface with a multimedia broadcast multicast service (MBMS)
gateway and an M2 interface with a multicast coordination entity
(MCE), and wherein the at least one processor is further configured
to: send an MBMS session start initiation to a broadcast multicast
service center (BM-SC) through the MCE, a mobility management
entity (MME), and the MBMS gateway to initiate an MBMS session with
the BM-SC.
24. The apparatus of claim 17, wherein the at least one processor
is further configured to receive information from a home evolved
node B (eNB) (HeNB) management system (HMS), wherein the MBSFN
subframes of the first base station are determined based on the
information received from the HMS.
25. The apparatus of claim 24, wherein the information from the HMS
indicates an MBSFN configuration, and wherein the at least one
processor is further configured to transmit, based on the MBSFN
configuration, at least one of a system information block (SIB) 13,
a multicast control channel (MCCH) change notification, an MCCH
synchronously with the first base station at the frequency, or a
multicast traffic channel (MTCH) synchronously with the first base
station at the frequency.
26. The apparatus of claim 17, wherein the at least one processor
is further configured to receive a system information block (SIB) 2
from the first base station, wherein the MBSFN subframes are
determined based on the received SIB 2.
27. The apparatus of claim 17, wherein the at least one processor
is further configured to: receive a system information block (SIB)
13 from the first base station; obtain an MBSFN configuration based
on the received SIB 13; and transmit, at the frequency, the SIB 13
and a multicast control channel (MCCH) change notification based on
the MBSFN configuration.
28. The apparatus of claim 17, wherein the at least one processor
is further configured to receive multicast channel (MCH) scheduling
information (MSI), wherein the MBSFN subframes are further
determined based on the received MSI.
29. The apparatus of claim 28, wherein the at least one processor
is further configured to: receive a system information block (SIB)
13 from the first base station; obtain a multicast control channel
(MCCH) from the first base station based on the received SIB 13;
obtain an MBSFN configuration based on the obtained MCCH and the
SIB 13; and transmit, at the frequency, the SIB 13, an MCCH change
notification, and the MCCH based on the MBSFN configuration,
wherein the MCCH is transmitted synchronously with the first base
station at the frequency.
30. A computer-readable medium, associated with a second base
station and storing computer executable code for wireless
communication, comprising code for: determining multicast broadcast
single frequency network (MBSFN) subframes used by a first base
station at a frequency, the first base station having a first power
class, the second base station having a second power class lower
than the first power class; determining, in the MBSFN subframes, a
first set of symbols used for control information by the first base
station and a second set of symbols used for MBSFN signals by the
first base station; transmitting, at the frequency, unicast control
information in a subset of the first set of symbols; and
transmitting, at the frequency, unicast data with a reduced power
in the second set of symbols.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 62/008,454, entitled "Improving MBMS
Coexistence in a Network with Multiple Types of Base Stations" and
filed on Jun. 5, 2014, which is expressly incorporated by reference
herein in its entirety.
BACKGROUND
[0002] 1. Field
[0003] The present disclosure relates generally to communication
systems, and more particularly, to improving multimedia broadcast
multicast service coexistence in a network with multiple types of
base stations.
[0004] 2. Background
[0005] Wireless communication systems are widely deployed to
provide various telecommunication services such as telephony,
video, data, messaging, and broadcasts. Typical wireless
communication systems may employ multiple-access technologies
capable of supporting communication with multiple users by sharing
available system resources (e.g., bandwidth, transmit power).
Examples of such multiple-access technologies include code division
multiple access (CDMA) systems, time division multiple access
(TDMA) systems, frequency division multiple access (FDMA) systems,
orthogonal frequency division multiple access (OFDMA) systems,
single-carrier frequency division multiple access (SC-FDMA)
systems, and time division synchronous code division multiple
access (TD-SCDMA) systems.
[0006] These multiple access technologies have been adopted in
various telecommunication standards to provide a common protocol
that enables different wireless devices to communicate on a
municipal, national, regional, and even global level. An example of
a telecommunication standard is Long Term Evolution (LTE). LTE is a
set of enhancements to the Universal Mobile Telecommunications
System (UMTS) mobile standard promulgated by Third Generation
Partnership Project (3GPP). LTE is designed to better support
mobile broadband Internet access by improving spectral efficiency,
lowering costs, improving services, making use of new spectrum, and
better integrating with other open standards using OFDMA on the
downlink (DL), SC-FDMA on the uplink (UL), and multiple-input
multiple-output (MIMO) antenna technology. However, as the demand
for mobile broadband access continues to increase, there exists a
need for further improvements in LTE technology. Preferably, these
improvements should be applicable to other multi-access
technologies and the telecommunication standards that employ these
technologies.
SUMMARY
[0007] In an aspect of the disclosure, a method, a
computer-readable medium, and an apparatus are provided. The method
is one for wireless communication of a user equipment (UE). The
method includes communicating with a second base station in a radio
resource control (RRC) connected state, receiving a multimedia
broadcast multicast service (MBMS) service from a first base
station while in an RRC connected state with the second base
station. The first base station having a first power class, and the
second base station having a second power class lower than the
first power class. The method further includes determining that the
UE is unable to decode multicast broadcast single frequency network
(MBSFN) signals of the MBMS service from the first base station and
receiving the MBMS service from the second base station through a
unicast channel upon determining that the UE is unable to decode
the MBSFN signals of the MBMS service from the first base station.
In an aspect, the method further includes maintaining an RRC idle
state with the first base station, determining that the UE is in
range of the second base station, establishing an RRC connected
state with the first base station, and moving in a handoff from the
first base station to the second base station upon determining that
the UE is in range of the second base station.
[0008] The computer-readable medium may be associated with a UE and
include code that when executed on at least one processor performs
the operations of communicating with a second base station in an
RRC connected state, receiving an MBMS service from a first base
station while in an RRC connected state with the second base
station, in which the first base station has a first power class,
and the second base station has a second power class lower than the
first power class, determining that the UE is unable to decode
MBSFN signals of the MBMS service from the first base station, and
receiving the MBMS service from the second base station through a
unicast channel upon determining that the UE is unable to decode
the MBSFN signals of the MBMS service from the first base
station.
[0009] In one aspect, the apparatus may include means for
communicating with a second base station in an RRC connected state,
means for receiving an MBMS service from a first base station while
in an RRC connected state with the second base station, the first
base station having a first power class, the second base station
having a second power class lower than the first power class, means
for determining that the UE is unable to decode MBSFN signals of
the MBMS service from the first base station, and means for
receiving the MBMS service from the second base station through a
unicast channel upon determining that the UE is unable to decode
the MBSFN signals of the MBMS service from the first base station.
The apparatus may further include means for maintaining an RRC idle
state with the first base station, means for determining that the
UE is in range of the second base station, means for establishing
an RRC connected state with the first base station, and means for
moving in a handoff from the first base station to the second base
station upon determining that the UE is in range of the second base
station.
[0010] In another aspect, the apparatus may include a memory and at
least one processor coupled to the memory, in which the processor
is configured to communicate with a second base station in an RRC
connected state, receive a MBMS service from a first base station
while in an RRC connected state with the second base station, the
first base station having a first power class, the second base
station having a second power class lower than the first power
class, determine that the UE is unable to decode MBSFN signals of
the MBMS service from the first base station, and receive the MBMS
service from the second base station through a unicast channel upon
determining that the UE is unable to decode the MBSFN signals of
the MBMS service from the first base station. The at least one
processor may be further configured to maintain an RRC idle state
with the first base station, determine that the UE is in range of
the second base station, establish an RRC connected state with the
first base station, and move in a handoff from the first base
station to the second base station upon determining that the UE is
in range of the second base station.
[0011] In another aspect of the disclosure, a method, a computer
program product, and an apparatus are provided. The method includes
receiving a composite signal comprising an MBSFN signal transmitted
by a first base station and a unicast interfering signal
transmitted by a second base station, the first base station having
a first power class, the second base station having a second power
class lower than the first power class, converting the received
composite signal to a frequency domain representation, estimating
the unicast interfering signal from the frequency domain converted
signal, converting the estimated unicast interfering signal into a
time domain interfering signal, subtracting the time domain
interfering signal from the received composite signal to obtain an
interference reduced signal, and decoding the interference reduced
signal to recover MBSFN data. In an aspect, the first base station
transmits symbols with an extended cyclic prefix, the second base
station transmits symbols with a normal cyclic prefix, and the
converting the estimated unicast interfering signal includes
converting the estimated unicast interfering signal into a set of
symbols in the time domain, appending a normal cyclic prefix to
each symbol, and appending two or more cyclic prefix appended
symbols together to obtain the time domain interfering signal. In
another aspect, the first base station transmits symbols with a
normal cyclic prefix, the second base station transmits symbols
with an extended cyclic prefix, and the converting the estimated
unicast interfering signal includes converting the estimated
unicast interfering signal into a set of symbols in the time
domain, appending an extended cyclic prefix to each symbol, and
appending one or more cyclic prefix appended symbols together to
obtain the time domain interfering signal.
[0012] In one aspect, the apparatus includes means for receiving a
composite signal comprising an MBSFN signal from a first base
station and a unicast interfering signal from a second base
station, the first base station having a first power class, the
second base station having a second power class lower than the
first power class, means for converting the received composite
signal to a frequency domain representation, means for estimating
the unicast interfering signal from the frequency domain converted
signal, means for converting the estimated unicast interfering
signal into a time domain interfering signal, means for subtracting
the time domain interfering signal from the received composite
signal to obtain an interference reduced signal, and means for
decoding the interference reduced signal to recover MBSFN data. In
an aspect, the first base station transmits symbols with an
extended cyclic prefix, the second base station transmits symbols
with a normal cyclic prefix, and the means for converting the
estimated unicast interfering signal is configured to convert the
estimated unicast interfering signal into a set of symbols in the
time domain, append a normal cyclic prefix to each symbol, and
append two or more cyclic prefix appended symbols together to
obtain the time domain interfering signal. In another aspect, the
first base station transmits symbols with a normal cyclic prefix,
the second base station transmits symbols with an extended cyclic
prefix, and the means for converting the estimated unicast
interfering signal is configured to convert the estimated unicast
interfering signal into a set of symbols in the time domain, append
an extended cyclic prefix to each symbol, and append one or more
cyclic prefix appended symbols together to obtain the time domain
interfering signal.
[0013] In another aspect, the apparatus may include a memory and at
least one processor coupled to the memory, and the at least one
processor is configured to receive a composite signal comprising an
MBSFN signal from a first base station and a unicast interfering
signal from a second base station, the first base station having a
first power class, the second base station having a second power
class lower than the first power class, convert the received
composite signal to a frequency domain representation, estimate the
unicast interfering signal from the frequency domain converted
signal, convert the estimated unicast interfering signal into a
time domain interfering signal, subtract the time domain
interfering signal from the received composite signal to obtain an
interference reduced signal, decode the interference reduced signal
to recover MBSFN data. In an aspect, the first base station
transmits symbols with an extended cyclic prefix, the second base
station transmits symbols with a normal cyclic prefix, and the at
least one processor is configured to convert the estimated unicast
interfering signal by converting the estimated unicast interfering
signal into a set of symbols in the time domain, appending a normal
cyclic prefix to each symbol, and appending two or more cyclic
prefix appended symbols together to obtain the time domain
interfering signal. In another aspect, the first base station
transmits symbols with a normal cyclic prefix, the second base
station transmits symbols with an extended cyclic prefix, and the
at least one processor is configured to convert the estimated
unicast interfering signal by converting the estimated unicast
interfering signal into a set of symbols in the time domain,
appending an extended cyclic prefix to each symbol, and appending
one or more cyclic prefix appended symbols together to obtain the
time domain interfering signal.
[0014] The computer-readable medium includes code that when
executed on at least one processor performs the operations of
receiving a composite signal comprising n MBSFN signal from a first
base station and a unicast interfering signal from a second base
station, the first base station having a first power class, the
second base station having a second power class lower than the
first power class, converting the received composite signal to a
frequency domain representation, estimating the unicast interfering
signal from the frequency domain converted signal, converting the
estimated unicast interfering signal into a time domain interfering
signal, subtracting the time domain interfering signal from the
received composite signal to obtain an interference reduced signal,
and decoding the interference reduced signal to recover MBSFN
data.
[0015] In another aspect of the disclosure, a method, a computer
program product, and an apparatus are provided. The apparatus may
be a femto cell, pico cell, relay node, or otherwise a cell/base
station with a power class lower than a power class of a macro
cell/base station. The apparatus determines MBSFN subframes at a
frequency of a first base station (e.g., macro cell or an eNB). The
first base station has a first power class, and the apparatus has a
second power class. The second power class is lower than the first
power class. The apparatus determines, in the MBSFN subframes, a
first set of symbols used for control information and a second set
of symbols used for MBSFN signals by the first base station. The
apparatus transmits, at the frequency, unicast control information
in a subset of the first set of symbols. The apparatus transmits,
at the frequency, unicast data with a reduced power in the second
set of symbols.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a diagram illustrating an example of a network
architecture.
[0017] FIG. 2 is a diagram illustrating an example of an access
network.
[0018] FIG. 3 is a diagram illustrating an example of a DL frame
structure in LTE.
[0019] FIG. 4 is a diagram illustrating an example of an UL frame
structure in LTE.
[0020] FIG. 5 is a diagram illustrating an example of a radio
protocol architecture for the user and control planes.
[0021] FIG. 6 is a diagram illustrating an example of an evolved
Node B and user equipment in an access network.
[0022] FIG. 7A is a diagram illustrating an example of an evolved
Multimedia Broadcast Multicast Service channel configuration in a
Multicast Broadcast Single Frequency Network.
[0023] FIG. 7B is a diagram illustrating a format of a Multicast
Channel Scheduling Information Media Access Control control
element.
[0024] FIG. 8 is a diagram illustrating an exemplary method for
improving MBMS coexistence in a network with multiple types of base
stations by maintaining MBMS service continuity through
unicast.
[0025] FIG. 9 is a flow chart of an exemplary method of improving
MBMS coexistence in a network with multiple types of base stations
by maintaining MBMS service continuity through unicast.
[0026] FIG. 10 is a diagram illustrating an exemplary method for
improving MBMS coexistence in a network with multiple types of base
stations via interference cancellation.
[0027] FIG. 11 is a flow chart of an exemplary method of improving
MBMS coexistence in a network with multiple types of base stations
via interference cancellation.
[0028] FIG. 12A is a flow chart of an exemplary method of improving
MBMS coexistence in a network with multiple types of base
stations.
[0029] FIG. 12B is a flow chart of an exemplary method of improving
MBMS coexistence in a network with multiple types of base
stations.
[0030] FIG. 13 is a diagram illustrating an exemplary network
architecture and method for improving MBMS coexistence in a network
with different types of base stations.
[0031] FIG. 14A is a diagram illustrating network architecture
configured to provide MBMS service.
[0032] FIG. 14B is a diagram illustrating an exemplary network
architecture and method for improving MBMS coexistence with
multiple types of base stations through base station
cooperation.
[0033] FIG. 15 is a flow chart of an exemplary method of improving
MBMS coexistence in a network with multiple types of base
stations.
[0034] FIG. 16 is a diagram illustrating an exemplary network
architecture and method for improving MBMS coexistence with
multiple types of base stations through base station
cooperation.
[0035] FIG. 17 is a flow chart of an exemplary method of improving
MBMS coexistence in a network with multiple types of base
stations.
[0036] FIG. 18 is a conceptual data flow diagram illustrating the
data flow between different modules/means/components in an
exemplary apparatus.
[0037] FIG. 19 is a diagram illustrating an example of a hardware
implementation for an apparatus employing a processing system.
[0038] FIG. 20 is a conceptual data flow diagram illustrating the
data flow between different modules/means/components in an
exemplary apparatus.
[0039] FIG. 21 is a diagram illustrating an example of a hardware
implementation for an apparatus employing a processing system.
[0040] FIG. 22 is a conceptual data flow diagram illustrating the
data flow between different modules/means/components in an
exemplary apparatus.
[0041] FIG. 23 is a diagram illustrating an example of a hardware
implementation for an apparatus employing a processing system.
DETAILED DESCRIPTION
[0042] The detailed description set forth below in connection with
the appended drawings is intended as a description of various
configurations and is not intended to represent the only
configurations in which the concepts described herein may be
practiced. The detailed description includes specific details for
the purpose of providing a thorough understanding of various
concepts. However, it will be apparent to those skilled in the art
that these concepts may be practiced without these specific
details. In some instances, well known structures and components
are shown in block diagram form in order to avoid obscuring such
concepts.
[0043] Several aspects of telecommunication systems will now be
presented with reference to various apparatus and methods. These
apparatus and methods will be described in the following detailed
description and illustrated in the accompanying drawings by various
blocks, modules, components, circuits, steps, processes,
algorithms, etc. (collectively referred to as "elements"). These
elements may be implemented using electronic hardware, computer
software, or any combination thereof. Whether such elements are
implemented as hardware or software depends upon the particular
application and design constraints imposed on the overall
system.
[0044] By way of example, an element, or any portion of an element,
or any combination of elements may be implemented with a
"processing system" that includes one or more processors. Examples
of processors include microprocessors, microcontrollers, digital
signal processors (DSPs), field programmable gate arrays (FPGAs),
programmable logic devices (PLDs), state machines, gated logic,
discrete hardware circuits, and other suitable hardware configured
to perform the various functionality described throughout this
disclosure. One or more processors in the processing system may
execute software. Software shall be construed broadly to mean
instructions, instruction sets, code, code segments, program code,
programs, subprograms, software modules, applications, software
applications, software packages, routines, subroutines, objects,
executables, threads of execution, procedures, functions, etc.,
whether referred to as software, firmware, middleware, microcode,
hardware description language, or otherwise.
[0045] Accordingly, in one or more exemplary embodiments, the
functions described may be implemented in hardware, software,
firmware, or any combination thereof. If implemented in software,
the functions may be stored on or encoded as one or more
instructions or code on a computer-readable medium.
Computer-readable media includes computer storage media. Storage
media may be any available media that can be accessed by a
computer. By way of example, and not limitation, such
computer-readable media can comprise a random-access memory (RAM),
a read-only memory (ROM), an electrically erasable programmable ROM
(EEPROM), compact disk ROM (CD-ROM) or other optical disk storage,
magnetic disk storage or other magnetic storage devices, or any
other medium that can be used to carry or store desired program
code in the form of instructions or data structures and that can be
accessed by a computer. Combinations of the above should also be
included within the scope of computer-readable media.
[0046] FIG. 1 is a diagram illustrating an LTE network architecture
100. The LTE network architecture 100 may be referred to as an
Evolved Packet System (EPS) 100. The EPS 100 may include one or
more user equipment (UE) 102, an Evolved UMTS Terrestrial Radio
Access Network (E-UTRAN) 104, an Evolved Packet Core (EPC) 110, and
an Operator's Internet Protocol (IP) Services 122. The EPS can
interconnect with other access networks, but for simplicity those
entities/interfaces are not shown. As shown, the EPS provides
packet-switched services, however, as those skilled in the art will
readily appreciate, the various concepts presented throughout this
disclosure may be extended to networks providing circuit-switched
services.
[0047] The E-UTRAN includes the evolved Node B (eNB) 106 and other
eNBs 108, and may include a Multicast Coordination Entity (MCE)
128. The eNB 106 provides user and control planes protocol
terminations toward the UE 102. The eNB 106 may be connected to the
other eNBs 108 via a backhaul (e.g., an X2 interface). The MCE 128
allocates time/frequency radio resources for evolved Multimedia
Broadcast Multicast Service (MBMS) (eMBMS), and determines the
radio configuration (e.g., a modulation and coding scheme (MCS))
for the eMBMS. The MCE 128 may be a separate entity or part of the
eNB 106. The eNB 106 may also be referred to as a base station, a
Node B, an access point, a base transceiver station, a radio base
station, a radio transceiver, a transceiver function, a basic
service set (BSS), an extended service set (ESS), or some other
suitable terminology. The eNB 106 provides an access point to the
EPC 110 for a UE 102. Examples of UEs 102 include a cellular phone,
a smart phone, a session initiation protocol (SIP) phone, a laptop,
a personal digital assistant (PDA), a satellite radio, a global
positioning system, a multimedia device, a video device, a digital
audio player (e.g., MP3 player), a camera, a game console, a
tablet, or any other similar functioning device. The UE 102 may
also be referred to by those skilled in the art as a mobile
station, a subscriber station, a mobile unit, a subscriber unit, a
wireless unit, a remote unit, a mobile device, a wireless device, a
wireless communications device, a remote device, a mobile
subscriber station, an access terminal, a mobile terminal, a
wireless terminal, a remote terminal, a handset, a user agent, a
mobile client, a client, or some other suitable terminology.
[0048] The eNB 106 is connected to the EPC 110. The EPC 110 may
include a Mobility Management Entity (MME) 112, a Home Subscriber
Server (HSS) 120, other MMEs 114, a Serving Gateway (S-GW) 116, a
Multimedia Broadcast Multicast Service (MBMS) Gateway (MBMS-GW)
124, a Broadcast Multicast Service Center (BM-SC) 126, and a Packet
Data Network (PDN) Gateway 118. The MME 112 is the control node
that processes the signaling between the UE 102 and the EPC 110.
Generally, the MME 112 provides bearer and connection management.
All user IP packets may be transferred through the Serving Gateway
116, which is connected to the PDN Gateway 118. The PDN Gateway 118
provides UE IP address allocation as well as other functions. The
PDN Gateway 118 and the BM-SC 126 are connected to the IP Services
122. The IP Services 122 may include the Internet, an intranet, an
IP Multimedia Subsystem (IMS), a Packed Switched (PS) Streaming
Service (PSS), and/or other IP services. The BM-SC 126 may provide
functions for MBMS user service provisioning and delivery. The
BM-SC 126 may serve as an entry point for content provider MBMS
transmission, may be used to authorize and initiate MBMS Bearer
Services within a public land mobile network (PLMN), and may be
used to schedule and deliver MBMS transmissions. The MBMS Gateway
124 may be used to distribute MBMS traffic to the eNBs (e.g., 106,
108) belonging to a Multicast Broadcast Single Frequency Network
(MBSFN) area broadcasting a particular service, and may be
responsible for session management (start/stop) and for collecting
eMBMS related charging information.
[0049] FIG. 2 is a diagram illustrating an example of an access
network 200 in an LTE network architecture. In this example, the
access network 200 is divided into a number of cellular regions
(cells) 202. One or more lower power class eNBs 208 may have
cellular regions 210 that overlap with one or more of the cells
202. The lower power class eNB 208 may be a femto cell (e.g., home
eNB (HeNB)), pico cell, micro cell, or remote radio head (RRH). The
macro eNBs 204 are each assigned to a respective cell 202 and are
configured to provide an access point to the EPC 110 for all the
UEs 206 in the cells 202. There is no centralized controller in
this example of an access network 200, but a centralized controller
may be used in alternative configurations. The eNBs 204 are
responsible for all radio related functions including radio bearer
control, admission control, mobility control, scheduling, security,
and connectivity to the serving gateway 116. An eNB may support one
or multiple (e.g., three) cells (also referred to as a sectors).
The term "cell" can refer to the smallest coverage area of an eNB
and/or an eNB subsystem serving a particular coverage area
depending on the context in which the term is used. Further, the
terms "eNB," "base station," and "cell" may be used interchangeably
herein.
[0050] The modulation and multiple access scheme employed by the
access network 200 may vary depending on the particular
telecommunications standard being deployed. In LTE applications,
OFDM is used on the DL and SC-FDMA is used on the UL to support
both frequency division duplex (FDD) and time division duplex
(TDD). As those skilled in the art will readily appreciate from the
detailed description to follow, the various concepts presented
herein are well suited for LTE applications. However, these
concepts may be readily extended to other telecommunication
standards employing other modulation and multiple access
techniques. By way of example, these concepts may be extended to
Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB).
EV-DO and UMB are air interface standards promulgated by the 3rd
Generation Partnership Project 2 (3GPP2) as part of the CDMA2000
family of standards and employs CDMA to provide broadband Internet
access to mobile stations. These concepts may also be extended to
Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA
(W-CDMA) and other variants of CDMA, such as TD-SCDMA; Global
System for Mobile Communications (GSM) employing TDMA; and Evolved
UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE
802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE and
GSM are described in documents from the 3GPP organization. CDMA2000
and UMB are described in documents from the 3GPP2 organization. The
actual wireless communication standard and the multiple access
technology employed will depend on the specific application and the
overall design constraints imposed on the system.
[0051] The eNBs 204 may have multiple antennas supporting MIMO
technology. The use of MIMO technology enables the eNBs 204 to
exploit the spatial domain to support spatial multiplexing,
beamforming, and transmit diversity. Spatial multiplexing may be
used to transmit different streams of data simultaneously on the
same frequency. The data streams may be transmitted to a single UE
206 to increase the data rate or to multiple UEs 206 to increase
the overall system capacity. This is achieved by spatially
precoding each data stream (i.e., applying a scaling of an
amplitude and a phase) and then transmitting each spatially
precoded stream through multiple transmit antennas on the DL. The
spatially precoded data streams arrive at the UE(s) 206 with
different spatial signatures, which enables each of the UE(s) 206
to recover the one or more data streams destined for that UE 206.
On the UL, each UE 206 transmits a spatially precoded data stream,
which enables the eNB 204 to identify the source of each spatially
precoded data stream.
[0052] Spatial multiplexing is generally used when channel
conditions are good. When channel conditions are less favorable,
beamforming may be used to focus the transmission energy in one or
more directions. This may be achieved by spatially precoding the
data for transmission through multiple antennas. To achieve good
coverage at the edges of the cell, a single stream beamforming
transmission may be used in combination with transmit
diversity.
[0053] In the detailed description that follows, various aspects of
an access network will be described with reference to a MIMO system
supporting OFDM on the DL. OFDM is a spread-spectrum technique that
modulates data over a number of subcarriers within an OFDM symbol.
The subcarriers are spaced apart at precise frequencies. The
spacing provides "orthogonality" that enables a receiver to recover
the data from the subcarriers. In the time domain, a guard interval
(e.g., cyclic prefix) may be added to each OFDM symbol to combat
inter-OFDM-symbol interference. The UL may use SC-FDMA in the form
of a DFT-spread OFDM signal to compensate for high peak-to-average
power ratio (PAPR).
[0054] FIG. 3 is a diagram 300 illustrating an example of a DL
frame structure in LTE. A frame (10 ms) may be divided into 10
equally sized subframes. Each subframe may include two consecutive
time slots. A resource grid may be used to represent two time
slots, each time slot including a resource block. The resource grid
is divided into multiple resource elements. In LTE, for a normal
cyclic prefix, a resource block contains 12 consecutive subcarriers
in the frequency domain and 7 consecutive OFDM symbols in the time
domain, for a total of 84 resource elements. For an extended cyclic
prefix, a resource block may contain 12 consecutive subcarriers in
the frequency domain and 6 consecutive OFDM symbols in the time
domain, for a total of 72 resource elements. Some of the resource
elements, indicated as R 302, 304, include DL reference signals
(DL-RS). The DL-RS include Cell-specific RS (CRS) (also sometimes
called common RS) 302 and UE-specific RS (UE-RS) 304. UE-RS 304 are
transmitted only on the resource blocks upon which the
corresponding physical DL shared channel (PDSCH) is mapped. The
number of bits carried by each resource element depends on the
modulation scheme. Thus, the more resource blocks that a UE
receives and the higher the modulation scheme, the higher the data
rate for the UE.
[0055] FIG. 4 is a diagram 400 illustrating an example of an UL
frame structure in LTE. The available resource blocks for the UL
may be partitioned into a data section and a control section. The
control section may be formed at the two edges of the system
bandwidth and may have a configurable size. The resource blocks in
the control section may be assigned to UEs for transmission of
control information. The data section may include all resource
blocks not included in the control section. The UL frame structure
results in the data section including contiguous subcarriers, which
may allow a single UE to be assigned all of the contiguous
subcarriers in the data section.
[0056] A UE may be assigned resource blocks 410a, 410b in the
control section to transmit control information to an eNB. The UE
may also be assigned resource blocks 420a, 420b in the data section
to transmit data to the eNB. The UE may transmit control
information in a physical UL control channel (PUCCH) on the
assigned resource blocks in the control section. The UE may
transmit only data or both data and control information in a
physical UL shared channel (PUSCH) on the assigned resource blocks
in the data section. A UL transmission may span both slots of a
subframe and may hop across frequency.
[0057] A set of resource blocks may be used to perform initial
system access and achieve UL synchronization in a physical random
access channel (PRACH) 430. The PRACH 430 carries a random sequence
and cannot carry any UL data/signaling. Each random access preamble
occupies a bandwidth corresponding to six consecutive resource
blocks. The starting frequency is specified by the network. That
is, the transmission of the random access preamble is restricted to
certain time and frequency resources. There is no frequency hopping
for the PRACH. The PRACH attempt is carried in a single subframe (1
ms) or in a sequence of few contiguous subframes and a UE can make
only a single PRACH attempt per frame (10 ms).
[0058] FIG. 5 is a diagram 500 illustrating an example of a radio
protocol architecture for the user and control planes in LTE. The
radio protocol architecture for the UE and the eNB is shown with
three layers: Layer 1, Layer 2, and Layer 3. Layer 1 (L1 layer) is
the lowest layer and implements various physical layer signal
processing functions. The L1 layer will be referred to herein as
the physical layer 506. Layer 2 (L2 layer) 508 is above the
physical layer 506 and is responsible for the link between the UE
and eNB over the physical layer 506.
[0059] In the user plane, the L2 layer 508 includes a media access
control (MAC) sublayer 510, a radio link control (RLC) sublayer
512, and a packet data convergence protocol (PDCP) 514 sublayer,
which are terminated at the eNB on the network side. Although not
shown, the UE may have several upper layers above the L2 layer 508
including a network layer (e.g., IP layer) that is terminated at
the PDN gateway 118 on the network side, and an application layer
that is terminated at the other end of the connection (e.g., far
end UE, server, etc.).
[0060] The PDCP sublayer 514 provides multiplexing between
different radio bearers and logical channels. The PDCP sublayer 514
also provides header compression for upper layer data packets to
reduce radio transmission overhead, security by ciphering the data
packets, and handover support for UEs between eNBs. The RLC
sublayer 512 provides segmentation and reassembly of upper layer
data packets, retransmission of lost data packets, and reordering
of data packets to compensate for out-of-order reception due to
hybrid automatic repeat request (HARQ). The MAC sublayer 510
provides multiplexing between logical and transport channels. The
MAC sublayer 510 is also responsible for allocating the various
radio resources (e.g., resource blocks) in one cell among the UEs.
The MAC sublayer 510 is also responsible for HARQ operations.
[0061] In the control plane, the radio protocol architecture for
the UE and eNB is substantially the same for the physical layer 506
and the L2 layer 508 with the exception that there is no header
compression function for the control plane. The control plane also
includes a radio resource control (RRC) sublayer 516 in Layer 3 (L3
layer). The RRC sublayer 516 is responsible for obtaining radio
resources (e.g., radio bearers) and for configuring the lower
layers using RRC signaling between the eNB and the UE.
[0062] FIG. 6 is a block diagram of an eNB 610 in communication
with a UE 650 in an access network. In the DL, upper layer packets
from the core network are provided to a controller/processor 675.
The controller/processor 675 implements the functionality of the L2
layer. In the DL, the controller/processor 675 provides header
compression, ciphering, packet segmentation and reordering,
multiplexing between logical and transport channels, and radio
resource allocations to the UE 650 based on various priority
metrics. The controller/processor 675 is also responsible for HARQ
operations, retransmission of lost packets, and signaling to the UE
650.
[0063] The transmit (TX) processor 616 implements various signal
processing functions for the L1 layer (i.e., physical layer). The
signal processing functions include coding and interleaving to
facilitate forward error correction (FEC) at the UE 650 and mapping
to signal constellations based on various modulation schemes (e.g.,
binary phase-shift keying (BPSK), quadrature phase-shift keying
(QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude
modulation (M-QAM)). The coded and modulated symbols are then split
into parallel streams. Each stream is then mapped to an OFDM
subcarrier, multiplexed with a reference signal (e.g., pilot) in
the time and/or frequency domain, and then combined together using
an Inverse Fast Fourier Transform (IFFT) to produce a physical
channel carrying a time domain OFDM symbol stream. The OFDM stream
is spatially precoded to produce multiple spatial streams. Channel
estimates from a channel estimator 674 may be used to determine the
coding and modulation scheme, as well as for spatial processing.
The channel estimate may be derived from a reference signal and/or
channel condition feedback transmitted by the UE 650. Each spatial
stream may then be provided to a different antenna 620 via a
separate transmitter 618TX. Each transmitter 618TX may modulate an
RF carrier with a respective spatial stream for transmission.
[0064] At the UE 650, each receiver 654RX receives a signal through
its respective antenna 652. Each receiver 654RX recovers
information modulated onto an RF carrier and provides the
information to the receive (RX) processor 656. The RX processor 656
implements various signal processing functions of the L1 layer. The
RX processor 656 may perform spatial processing on the information
to recover any spatial streams destined for the UE 650. If multiple
spatial streams are destined for the UE 650, they may be combined
by the RX processor 656 into a single OFDM symbol stream. The RX
processor 656 then converts the OFDM symbol stream from the
time-domain to the frequency domain using a Fast Fourier Transform
(FFT). The frequency domain signal comprises a separate OFDM symbol
stream for each subcarrier of the OFDM signal. The symbols on each
subcarrier, and the reference signal, are recovered and demodulated
by determining the most likely signal constellation points
transmitted by the eNB 610. These soft decisions may be based on
channel estimates computed by the channel estimator 658. The soft
decisions are then decoded and deinterleaved to recover the data
and control signals that were originally transmitted by the eNB 610
on the physical channel. The data and control signals are then
provided to the controller/processor 659.
[0065] The controller/processor 659 implements the L2 layer. The
controller/processor can be associated with a memory 660 that
stores program codes and data. The memory 660 may be referred to as
a computer-readable medium. In the UL, the controller/processor 659
provides demultiplexing between transport and logical channels,
packet reassembly, deciphering, header decompression, control
signal processing to recover upper layer packets from the core
network. The upper layer packets are then provided to a data sink
662, which represents all the protocol layers above the L2 layer.
Various control signals may also be provided to the data sink 662
for L3 processing. The controller/processor 659 is also responsible
for error detection using an acknowledgement (ACK) and/or negative
acknowledgement (NACK) protocol to support HARQ operations.
[0066] In the UL, a data source 667 is used to provide upper layer
packets to the controller/processor 659. The data source 667
represents all protocol layers above the L2 layer. Similar to the
functionality described in connection with the DL transmission by
the eNB 610, the controller/processor 659 implements the L2 layer
for the user plane and the control plane by providing header
compression, ciphering, packet segmentation and reordering, and
multiplexing between logical and transport channels based on radio
resource allocations by the eNB 610. The controller/processor 659
is also responsible for HARQ operations, retransmission of lost
packets, and signaling to the eNB 610.
[0067] Channel estimates derived by a channel estimator 658 from a
reference signal or feedback transmitted by the eNB 610 may be used
by the TX processor 668 to select the appropriate coding and
modulation schemes, and to facilitate spatial processing. The
spatial streams generated by the TX processor 668 may be provided
to different antenna 652 via separate transmitters 654TX. Each
transmitter 654TX may modulate an RF carrier with a respective
spatial stream for transmission.
[0068] The UL transmission is processed at the eNB 610 in a manner
similar to that described in connection with the receiver function
at the UE 650. Each receiver 618RX receives a signal through its
respective antenna 620. Each receiver 618RX recovers information
modulated onto an RF carrier and provides the information to a RX
processor 670. The RX processor 670 may implement the L1 layer.
[0069] The controller/processor 675 implements the L2 layer. The
controller/processor 675 can be associated with a memory 676 that
stores program codes and data. The memory 676 may be referred to as
a computer-readable medium. In the UL, the controller/processor 675
provides demultiplexing between transport and logical channels,
packet reassembly, deciphering, header decompression, control
signal processing to recover upper layer packets from the UE 650.
Upper layer packets from the controller/processor 675 may be
provided to the core network. The controller/processor 675 is also
responsible for error detection using an ACK and/or NACK protocol
to support HARQ operations.
[0070] FIG. 7A is a diagram 750 illustrating an example of an
evolved MBMS (eMBMS) channel configuration in an MBSFN. The eNBs
752 in cells 752' may form a first MBSFN area and the eNBs 754 in
cells 754' may form a second MBSFN area. The eNBs 752, 754 may each
be associated with other MBSFN areas, for example, up to a total of
eight MBSFN areas. A cell within an MBSFN area may be designated a
reserved cell. Reserved cells do not provide multicast/broadcast
content, but are time-synchronized to the cells 752', 754' and may
have restricted power on MBSFN resources in order to limit
interference to the MBSFN areas. Each eNB in an MBSFN area
synchronously transmits the same eMBMS control information and
data. Each area may support broadcast, multicast, and unicast
services. A unicast service is a service intended for a specific
user, e.g., a voice call. A multicast service is a service that may
be received by a group of users, e.g., a subscription video
service. A broadcast service is a service that may be received by
all users, e.g., a news broadcast. Referring to FIG. 7A, the first
MBSFN area may support a first eMBMS broadcast service, such as by
providing a particular news broadcast to UE 770. The second MBSFN
area may support a second eMBMS broadcast service, such as by
providing a different news broadcast to UE 760. Each MBSFN area
supports a plurality of physical multicast channels (PMCH) (e.g.,
15 PMCHs). Each PMCH corresponds to a multicast channel (MCH). Each
MCH can multiplex a plurality (e.g., 29) of multicast logical
channels. Each MBSFN area may have one multicast control channel
(MCCH). As such, one MCH may multiplex one MCCH and a plurality of
multicast traffic channels (MTCHs) and the remaining MCHs may
multiplex a plurality of MTCHs.
[0071] A UE can camp on an LTE cell to discover the availability of
eMBMS service access and a corresponding access stratum
configuration. In a first operation, the UE may acquire a system
information block (SIB) 13 (SIB13). In a second operation, based on
the SIB13, the UE may acquire an MBSFN Area Configuration message
on an MCCH. In a third operation, based on the MBSFN Area
Configuration message, the UE may acquire an MCH scheduling
information (MSI) MAC control element. The SIB13 may indicate (1)
an MBSFN area identifier of each MBSFN area supported by the cell;
(2) information for acquiring the MCCH such as an MCCH repetition
period (e.g., 32, 64, . . . , 256 frames), an MCCH offset (e.g., 0,
1, . . . , 10 frames), an MCCH modification period (e.g., 512, 1024
frames), a signaling modulation and coding scheme (MCS), subframe
allocation information indicating which subframes of the radio
frame as indicated by repetition period and offset can transmit
MCCH; and (3) an MCCH change notification configuration. There is
one MBSFN Area Configuration message for each MBSFN area. The MBSFN
Area Configuration message may indicate (1) a temporary mobile
group identity (TMGI), which may identify an MBMS service within a
PLMN, and an optional session identifier of each MTCH identified by
a logical channel identifier within the PMCH, and (2) allocated
resources (i.e., radio frames and subframes) for transmitting each
PMCH of the MBSFN area and the allocation period (e.g., 4, 8, . . .
, 256 frames) of the allocated resources for all the PMCHs in the
area, and (3) an MCH scheduling period (MSP) (e.g., 8, 16, 32, . .
. , or 1024 radio frames) over which the MSI MAC control element is
transmitted.
[0072] FIG. 7B is a diagram 790 illustrating the format of an MSI
MAC control element. The MSI MAC control element may be sent once
each MSP. The MSI MAC control element may be sent in the first
subframe of each scheduling period of the PMCH. The MSI MAC control
element can indicate the stop frame and subframe of each MTCH
within the PMCH. There may be one MSI per PMCH per MBSFN area.
[0073] In networks that support MBMS service through MBSFN
transmission, not all types of base stations deployed within such
networks may support MBSFN transmission. For example, in an LTE
network, eNBs may support MBSFN transmissions, while femto cells,
pico cells, and relay nodes may not. The lack of support for MBSFN
transmission in femto cells, for example, may be due to issues
related to synchronization between a femto cell and an eNB, lack of
control of the femto cell by a network operator, the femto cell's
lack of MBSFN awareness, femto cell cost and capability, backhaul
accessibility, and femto cell configuration.
[0074] When certain lower powered base stations like femto cells do
not support MBSFN transmissions, such lower powered base stations
can cause interference to MBMS service for a UE. Interference can
occur when such lower powered base stations transmit unicast
signals at the same frequency that MBSFN signals are being
transmitted by a higher powered base station. For example, a UE
within the coverage area of a femto cell may not efficiently
receive MBMS service due to the interference caused by the femto
cell to the MBSFN signal being transmitted by an eNB. Interference
may be especially severe when the femto cell and the eNB are
transmitting on the same frequency. As such, a need exists to
improve MBMS coexistence in networks that utilize MBSFN
transmission and deploy multiple types of base stations, some of
which do not support MBSFN transmissions. Although the examples
above have been discussed with respect to a femto cell, the same
need applies to other types of base stations, such as relay nodes,
which also do not support MBSFN transmissions. Also, the same need
applies to pico cells when pico cells do not participate in MBSFN
transmissions.
[0075] FIG. 8 is a diagram 800 illustrating an exemplary method for
improving MBMS coexistence in a network with multiple types of base
stations by maintaining MBMS service continuity through unicast. A
first base station 802 supports an MBSFN area denoted by cell 804.
The first base station 802 has a first power class and may be an
eNB. A UE 810 is located within cell 804 and maintains an RRC idle
state with the first base station 802. The UE 810 is also within a
region 806, which is the coverage area of a second base station
808. The second base station 808 has a second power class in which
the second power class may be lower than the first power class. The
second base station 808 may be a femto cell. The UE 810 receives
signals from both the first base station 802 and the second base
station 808. In one configuration, the UE 810 may receive MBSFN
signals 812 from the first base station 802 and interfering signals
from the second base station 808. If the second base station 808
transmits the interfering signals at the same frequency that the
first base station 802 transmits the MBSFN signals 812, the
interfering signals may cause severe interference to the UE 810
attempting to receive and decode the MBSFN signals 812 for MBMS
service.
[0076] The UE 810 may improve the MBMS service, however, if the UE
810 has access to the second base station 808. For example, the UE
810 would have access to the second base station 808 if the
identity of the second base station 808 belongs to the Closed
Subscriber Group (CSG) whitelist of the UE 810. Because the UE 810
is in region 806, the UE 810 may determine 816 that the UE 810 is
in range of the second base station 808. The UE 810 may receive a
cell ID from the second base station 808. Based on the cell ID, the
UE 810 may determine that the second base station 808 belongs to
the UE 810's CSG whitelist. The UE 810 may establish an RRC
connected state with the first base station 802. Afterwards, the UE
810 may be handed over from the first base station 802 to the
second base station 808, thereby establishing an RRC connected
state with the second base station 808, upon determining that the
UE 810 is in range of the second base station 808.
[0077] In one configuration, the UE 810 may be handed over from the
first base station 802 to the second base station 808 if the signal
strength (e.g., signal to noise ratio (SNR)) from the second base
station 808 exceeds a threshold or is greater than the signal
strength from first base station 802. The UE 810 may report the
signal strength from the second base station 808 to the first base
station 802. The first base station 802 may hand off the UE 810 to
the second base station 808 based on the reported signal
strength.
[0078] After the handoff, the UE 810 may communicate with the
second base station 808 in an RRC connected state. During this
time, the UE 810 may receive MBMS service from the first base
station 802 while being in an RRC connected state with the second
base station 808. The MBMS service from the first base station 802
may be transmitted to the UE 810 through MBSFN signals 812. If the
MBSFN signals 812 can be decoded, the UE 810 may autonomously
release the unicast channel established with the second base
station 808 and enter into an RRC idle state with the second base
station 808. However, if the UE 810 determines that the UE 810 is
unable to decode the MBSFN signals 812 of the MBMS service from the
first base station 802, the UE 810 may decide to receive MBMS
service from the second base station 808 through unicast signals
814 transmitted by the second base station 808. Thus, by entering
an RRC connected state with the second base station 808 while
attempting to decode the MBSFN signals 812 from the first base
station 802, the UE 810 can choose to receive MBMS service from the
second base station 808 with minimal delay if the UE 810 determines
that the UE 810 cannot decode the MBSFN signals 812 from the first
base station 802.
[0079] FIG. 9 is a flow chart 900 of an exemplary method of
improving MBMS coexistence in a network with multiple types of base
stations by maintaining MBMS service continuity through unicast.
The method may be performed by a UE (e.g., the UE 810). At block
902, the UE may be within a cell served by a first base station and
may maintain an RRC idle state with a first base station. The first
base station may have a first power class. For example, the UE 810
operates in an LTE network and is located within a cell served by
the first base station 802. In this example, the UE 810 maintains
an RRC idle state with the first base station 802.
[0080] At block 904, the UE may determine that the UE is in range
of an area served by a second base station. For example, the UE 810
may detect signals from the second base station 808 and determine
that the UE 810 is in range of an area served by the second base
station 808. The UE 810 may determine that the UE 810 has access to
the second base station 808 if the identity of the second base
station 808 belongs to the CSG whitelist of the UE 810. For
example, the UE 810 may receive a cell ID from the second base
station 808, and based on the cell ID, determine that the second
base station 808 belongs to the UE's CSG whitelist.
[0081] At block 906, the UE may establish an RRC connected state
with the first base station. For example, after determining that
the UE 810 is in range of the second base station 808, the UE 810
may determine that the second base station 808 is on the UE 810's
CSG whitelist based on a received cell ID. The UE 810 may establish
an RRC connected state with the first base station 802, knowing
that the second base station 808 cannot support MBSFN
transmission.
[0082] At block 908, the UE may be handed over from the first base
station to the second base station upon determining that the UE is
in range of the second base station. For example, after the UE 810
determines that the UE 810 is in range of the second base station
808 and that the second base station 808 is on the UE 810's CSG
whitelist, the UE 810 may report the received signal strength from
the second base station 808 to the first base station 802. The
first base station 802 may determine that the signal strength
exceeds a threshold (e.g., greater than -70 dBm) and subsequently
hand off the UE 810 from the first base station 802 to the second
base station 808.
[0083] At block 910, the UE may communicate with the second base
station in an RRC connected state. For example, after the UE 810
has been handed off from the first base station 802 to the second
base station 808, the UE 810 may communicate with the second base
station 808 in an RRC connected state.
[0084] At block 912, the UE may receive an MBMS service from a
first base station while in an RRC connected state with the second
base station. For example, the UE 810 may receive MBMS service from
the first base station 802 while in an RRC connected state with the
second base station 808. If the UE 810 can successfully receive the
MBMS service from the first base station 802, the UE 810 may decide
to release the unicast channel established with the second base
station 808 and enter into an RRC idle state with the second base
station 808.
[0085] At block 914, however, the UE may determine that the UE is
unable to decode the MBSFN signals of the MBMS service from the
first base station. For example, the UE 810 may determine that the
UE 810 is unable to decode the MBSFN signals 812 of the MBMS
service from the first base station 802 because the signal to noise
ratio of the received signal from the first base station 802 is too
low or because the received signal strength is below a threshold
(e.g., <-100 dBm). In another example, the UE 810 may determine
that the UE 810 is unable to decode the MBSFN signals 812 of the
MBMS service from the first base station 802 because the block
error rate is too high.
[0086] At block 916, the UE may receive the MBMS service from the
second base station through a unicast channel upon determining that
the UE is unable to decode the MBSFN signals of the MBMS service
from the first base station. For example, the UE 810 may receive
the MBMS service from the second base station 808 through the
unicast signals 814 upon determining that the UE 810 is unable to
decode the MBSFN signals 812 of the MBMS service from the first
base station 802.
[0087] FIG. 10 is a diagram 1000 illustrating an exemplary method
for improving MBMS coexistence in a network with multiple types of
base stations via interference cancellation. A first base station
1002 supports an MBSFN area denoted by cell 1004. The first base
station 1002 has a first power class and may be an eNB. A UE 1010
is located within the cell 1004 and maintains an RRC idle state
with the first base station 1002. The UE 1010 is also within a
region 1006, which is the coverage area of a second base station
1008. The second base station 1008 has a second power class, and
the second power class may be lower than the first power class. The
second base station 1008 may be a femto cell, pico cell, relay
node, or other lower power class base station. The UE 1010 receives
signals from both the first base station 1002 and the second base
station 1008. In one configuration, the UE 1010 may receive a
composite signal 1016 that includes an MBSFN signal 1012 from the
first base station 1002 and a unicast interfering signal 1014 from
the second base station 1008. If the second base station 1008
transmits the unicast interfering signal 1014 at the same frequency
that the first base station 1002 transmits the MBSFN signal 1012,
the unicast interfering signal 1014 may cause severe interference
to the UE 1010 attempting to receive and decode the MBSFN signal
1012 for MBMS service.
[0088] If the second base station 1008 is on the CSG whitelist of
the UE 1010, the UE 1010 can receive the MBMS service through the
second base station 1008 as discussed above. However, the UE 1010
may not have access to the second base station 1008, may not know
the type of base station/cell detected, or may not want to prepare
for handoff to the second base station 1008. In such cases, the UE
1010 may reduce interference by canceling at least some of the
unicast interfering signal 1014 transmitted by the second base
station 1008 when decoding the composite signal 1016 that includes
the MBSFN signals 1012 transmitted by the first base station
1002.
[0089] Different methods may be used by the UE 1010 to cancel
interference depending on whether the MBSFN signal 1012 and the
unicast interfering signal 1014 have the same or different cyclic
prefixes. When the MBSFN signal 1012 and the unicast interfering
signal 1014 have the same cyclic prefix (e.g., an extended cyclic
prefix), the UE 1010 may cancel the unicast interfering signal 1014
based on channel estimation, traffic to power ratio, rank,
precoding, and/or the mean of the modulation symbol of the unicast
interfering signal 1014 in the frequency domain. Initially, the UE
1010 may reconstruct the unicast interfering signal 1014 in the
frequency domain. Subsequently, the UE 1010 may cancel the unicast
interfering signal 1014 in the frequency domain and capture the
cancellation noise.
[0090] However, if the MBSFN signal 1012 and the unicast
interfering signal 1014 have different cyclic prefixes (e.g., the
MBSFN signal 1012 has an extended cyclic prefix and the unicast
interfering signal 1014 has a normal cyclic prefix), a different
method of interference cancellation may be used. In one aspect,
when cyclic prefixes are the same, frequency domain cancellation
may be used to reduce interference. However, when cyclic prefixes
are different, time domain cancellation may be used to reduce
interference. In time domain cancellation, subframe or symbol level
based cancellation is performed due to the misalignment of the
symbol boundaries between unicast and MBSFN transmissions. An
appropriate cyclic prefix length is appended to each symbol of the
estimated interfering signal before the cancellation.
[0091] To illustrate time domain cancellation, referring to FIG.
10, the UE 1010 may receive a composite signal 1016 that includes
the MBSFN signal 1012 from the first base station 1002 and the
unicast interfering signal 1014 from a second base station 1008.
The first base station 1002 may have a first power class, and the
second base station 1008 may have a second power class that is
lower than the first power class. The received composite signal
1016 may be in the time domain. Upon receiving the composite signal
1016, the UE 1010 may save the composite signal 1016 in a buffer.
The UE 101 may perform a series of operations 1018 in an attempt to
cancel the unicast interfering signal 1014 from the received
composite signal 1016. The UE 1010 may convert the received
composite signal 1016 from a time domain representation to a
frequency domain representation by using, for example, a Fast
Fourier Transform (FFT). The UE 1010 may estimate the unicast
interfering signal 1014 from the frequency domain converted signal.
In one aspect, the UE 1010 may estimate the unicast interfering
signal 1014 by estimating or determining one or more relevant
parameters related to unicast signal transmission. For example, the
UE 1010 may estimate one or more of a unicast channel, traffic to
pilot ratio, rank (i.e., number of layers), precoding matrix,
transmission mode, modulation order, modulation symbol, and
residual interference. In some instances, one or more of these
parameters may be transmitted to the UE 1010 from a wireless
network (e.g., via network assistance from the first base station
1002). Based on one or more of these parameters, the UE 1010 may
estimate the unicast interfering signal 1014. The UE 1010 may
convert the estimated unicast interfering signal from the frequency
domain to the time domain using, for example, Inverse Fast Fourier
Transform (IFFT), to obtain a time domain estimated unicast
interfering signal.
[0092] The UE 1010 may convert the estimated unicast interfering
signal from the frequency domain to the time domain under two
configurations. In one configuration, the first base station 1002
may transmit symbols with an extended cyclic prefix (e.g., an MBSFN
subframe with 12 symbols), and the second base station 1008 may
transmit symbols with a normal cyclic prefix (e.g., a unicast
subframe with 14 symbols). In this configuration, the UE 1010 may
convert the estimated unicast interfering signal into a set of
symbols in the time domain. Because the unicast interfering signal
1014 has a normal cyclic prefix, the UE 1010 may append a normal
cyclic prefix to each symbol in the time domain. To cancel
interference from MBSFN signal 1012, which has an extended cyclic
prefix, the UE 1010 may need at least two symbols from the
estimated unicast interfering signal with appended normal prefixes.
Accordingly, the UE 1010 may append two or more cyclic prefix
appended symbols together to obtain the time domain interfering
signal.
[0093] In another configuration, the first base station 1002 may
transmit symbols with a normal cyclic prefix (e.g., an MBSFN
subframe with 14 symbols), and the second base station 1008 may
transmit symbols with an extended cyclic prefix (e.g., a unicast
subframe with 12 symbols). In this configuration, the UE 1010 may
convert the estimated unicast interfering signal into a set of
symbols in the time domain. Because the unicast interfering signal
1014 has an extended cyclic prefix, the UE 1010 may append an
extended cyclic prefix to each symbol in the time domain. To cancel
interference from MBSFN signal 1012, which has a normal cyclic
prefix, the UE 1010 may use one or more symbols from the estimated
unicast interfering signal with appended extended prefix.
Accordingly, the UE 1010 may append one or more cyclic prefix
appended symbols together to obtain the time domain interfering
signal.
[0094] Having obtained the estimated time domain interfering signal
in either of the aforementioned configurations, the UE 1010 may
subtract the estimated time domain interfering signal from the
received composite signal 1016 to obtain an interference reduced
signal. The UE 1010 may then decode the interference reduced signal
to recover/obtain MBSFN data/transmission that approximates (or is
approximately equal to) the MBSFN signal 1012 transmitted by the
first base station 1002.
[0095] As previously mentioned, in an aspect, instead of performing
symbol level based cancellation, the UE 1010 may perform subframe
level based cancellation (excluding unicast control symbols) due to
misaligned symbol boundaries between unicast and MBSFN signals when
the cyclic prefix length is different.
[0096] Further, by improving MBMS coexistence using interference
cancellation, no coordination is needed between the second base
station 1008 and/or other lower powered base stations) and the
first base station 1002. The second base station 1008 also need not
be aware of the MBSFN subframes being transmitted by the first base
station 1002.
[0097] FIG. 11 is a flow chart 1100 of an exemplary method of
improving MBMS coexistence in a network with multiple types of base
stations via interference cancellation. The method may be performed
by a UE (e.g., the UE 1010). At block 1102, the UE may receive a
composite signal that includes an MBSFN signal from a first base
station and a unicast interfering signal from a second base
station. The first base station may have a first power class. The
second base station may have a second power class. The second power
class may be lower than the first power class. For example,
referring to FIG. 10, the UE 1010 may receive a composite signal
1016 that includes an MBSFN signal 1012 from a first base station
1002 and a unicast interfering signal 1014 from a second base
station 1008. The first base station may be a macro eNB/cell with a
first power class. The second base station may be a base
station/cell (e.g., femto cell) with a second power class, such
that the second power class is lower than the first power
class.
[0098] At block 1104, the UE may convert the received composite
signal from a time domain to a frequency domain. For example, the
UE 1010 may perform an FFT on the received composite signal 1016 to
convert the received composite signal 1016 from the time domain to
the frequency domain.
[0099] At block 1106, the UE may estimate the unicast interfering
signal from the frequency domain converted signal. In one aspect,
the UE may estimate the unicast interfering signal by estimating or
determining one or more relevant parameters related to unicast
signal transmission. For example, the UE 1010 may estimate one or
more of a unicast channel, traffic to pilot ratio, rank (i.e.,
number of layers), precoding matrix, transmission mode, modulation
order, modulation symbol, and residual interference. In some
instances, one or more of these parameters may be transmitted to
the UE 1010 from a wireless network (e.g., via network assistance
from the first base station 1002). Based on one or more of these
parameters, the UE 1010 may estimate the unicast interfering signal
1014.
[0100] At block 1108, the UE may convert the estimated unicast
interfering signal into a time domain interfering signal. For
example, the UE 1010 may perform an IFFT on the estimated unicast
interfering signal to convert the estimated unicast interfering
signal from the frequency domain to the time domain.
[0101] Continuing with block 1108, the UE may convert the estimated
unicast interfering signal from the frequency domain to the time
domain under two configurations as shown in FIGS. 12A and 12B,
which are flow charts of exemplary methods for improving MBMS
coexistence in a network with multiple types of base stations using
interference cancellation. In one configuration, the first base
station transmits symbols with an extended prefix, and the second
base station transmits symbols with a normal cyclic prefix. In this
configuration, as shown in FIG. 12A, at block 1202, the UE may
convert the estimated unicast interfering signal into a set of
symbols in the time domain. For example, the UE 1010 may convert
the estimated unicast interfering signal into a set of symbols in
the time domain using IFFT. At block 1204, the UE may append a
normal cyclic prefix to each symbol. At block 1206, the UE may
append two or more cyclic prefix appended symbols together to
obtain the time domain interfering signal. The number of cyclic
prefix appended symbols may have a time duration equal to or
greater than the time duration of the number of symbols in the
composite signal from which interference is to be canceled. For
example, the UE 1010 may append a normal cyclic prefix to each
symbol of the estimated unicast interfering signal. Then, the UE
1010 may append two or more normal cyclic prefix appended symbols
together such that the number of cyclic prefix appended symbols
have a time duration equal to or greater than the time duration of
the number of symbols in the composite signal 1016 from which
interference is to be canceled.
[0102] In another configuration, the first base station transmits
symbols with a normal cyclic prefix, and the second base station
transmits symbols with an extended prefix. In this configuration,
as shown in FIG. 12B, at block 1252, the UE may convert the
estimated unicast interfering signal into a set of symbols in the
time domain. For example, the UE 1010 may perform IFFT on the
estimated unicast interfering signal to convert the estimated
unicast interfering signal from the frequency domain to the time
domain. At block 1254, the UE may append an extended cyclic prefix
to each symbol. At block 1256, the UE may append one or more cyclic
prefix appended symbols together to obtain the time domain
interfering signal. The number of cyclic prefix appended symbols
may have a time duration equal to or greater than the time duration
of the number of symbols in the composite signal from which
interference is to be canceled. For example, the UE 1010 may append
an extended cyclic prefix to each symbol of the estimated unicast
interfering signal. Then, the UE 1010 may append one or more normal
cyclic prefix appended symbols together such that the number of
cyclic prefix appended symbols have a time duration equal to or
greater than the time duration of the number of symbols in the
composite signal 1016 from which interference is to be
canceled.
[0103] Referring back to FIG. 11, having obtained the time domain
interfering signal, at block 1110, the UE may subtract the time
domain interfering signal from the received composite signal to
obtain the interference reduced signal. At block 1112, the UE may
decode the interference reduced signal to obtain/recover an MBSFN
transmission from the received composite signal. For example, the
UE 1010 may convert the interference reduced signal to the
frequency domain by performing FFT on the interference reduced
signal and decode the interference reduced signal in the frequency
domain.
[0104] FIG. 13 is a diagram 1300 illustrating an exemplary network
architecture and method for improving MBMS coexistence in a network
with different types of base stations. As shown in FIG. 13, a
network may have a first base station (e.g., eNB3). The first base
station may have a first power class. The network may also have
other base stations with the first power class (e.g., eNB1, eNB2).
The eNBs 1, 2, 3 may each be connected with one or more MME/S-GWs
through an S1 interface, which has a user and control plane
interface. The eNBs 1, 2, 3 may be connected to each other via a
backhaul (e.g., an X2 interface). The network may also have a
second base station (e.g., HeNB1, a femto cell) with a second power
class. The second power class may be lower than the first power
class. The network may also have other base stations with the
second power class (e.g., HeNB2, HeNB3). The network may also have
other types of base stations of different lower power classes such
as pico cells, micro cells, or relay nodes. In one configuration,
the second base station (e.g., HeNB1) may have an S1 interface with
the MME/S-GW. In another configuration, the second base station
(e.g., HeNB2, HeNB3) may have an S1 interface with a HeNB Gateway
(HeNB GW). In this configuration, the HeNB GW may have an S1
interface with one or more MME/S-GWs. In yet another configuration,
the second base station (e.g., HeNB3) may have an S5 interface with
an MME/S-GW. The second base station and other base stations with
the same power class (e.g., HeNB1, HeNB2, HeNB3) may also be
connected via a backhaul (e.g., the X2 interface).
[0105] When a network, such as the one in FIG. 13, has multiple
types of base stations with different power classes, there may be
interference observed at the UE when the first base station of a
first power class (e.g., the eNB3) transmits MBSFN signals for MBMS
service on the same frequency that the second base station of a
second power class (e.g., HeNB1) transmits unicast signals. As
previously discussed, the UE may reduce some of the interference by
receiving the MBMS service via a unicast signal from the second
base station if the second base station is on the UE's CSG
whitelist. Alternatively, the UE may reduce the interference by
attempting to cancel at least some of the interference from the
second base station. In addition to these methods, the interference
may also be ameliorated by cooperation from the second base
station, if the second base station is aware of the MBSFN subframes
being utilized for MBMS transmission.
[0106] The second base station may cooperate with the first base
station to improve MBMS coexistence in a network by transmitting
MBSFN control signals to the UE. In one configuration, the second
base station may perform network listening (e.g., behave like a UE
and listen for transmissions from an eNB) and receive a SIB 2 from
the first base station and determine the MBSFN subframes of the
first base station based on the received SIB 2. In an aspect, the
received SIB 2 may include information indicating which subframes
are MBSFN subframes and/or which subframes are not MBSFN subframes.
In another configuration, using network listening, the second base
station may receive MSI from the first base station and determine
the MBSFN subframes of the first base station based on the received
MSI. The MSI may list which MBMS services are scheduled on which
MBSFN subframes. By receiving the MSI, the second base station may
know the occupied MBSFN subframes for MBMS service and may transmit
MBSFN signals accordingly. In an aspect, an MCCH may reserve a set
of MBSFN subframes, which may be more than all the services
require, and the MSI may list all of the MBSFN subframes allocated
to all services. In another configuration, using network listening,
the second base station may receive SIB 13 from the first base
station. The second base station may obtain the MBSFN configuration
based on the received SIB 13. The second base station may also
obtain an MCCH based on the received SIB 13. The second base
station may obtain the MBSFN configuration based on the obtained
MCCH and the SIB 13, and the MBSFN configuration would have
information on the MBSFN subframes of the first base station. Of
these options for obtaining information on the MBSFN subframes, the
MSI may have more accurate information regarding MBSFN subframes
used for MBMS compared to MCCH, SIB 13, and SIB 2.
[0107] Having determined the MBSFN subframes of the first base
station, the second base station may determine, in the MBSFN
subframes, a first set of symbols used for control information and
a second set of symbols used for MBSFN signals (e.g., user data) by
the first base station. The second base station may determine the
first and second set of symbols via network listening (e.g.,
listening to MCCH transmitted from the first base station). After
this determination, the second base station may transmit unicast
control information in a subset of the first set of symbols (e.g.,
in the unicast control region). The second base station may
transmit unicast data with reduced power in the second set of
symbols so as to reduce interference to the UE during MBSFN
transmission. The reduced power may be zero power such that the
second base station is effectively muting the unicast data in the
second set of symbols. For example, the first base station may be
an eNB, and the second base station may be a femto cell. The eNB
may transmit MBSFN signals on a set of MBSFN subframes. The femto
cell may determine which MBSFN subframes are being used by the eNB
for MBSFN signal transmission by listening to SIB 13. In those
MBSFN subframes, the femto cell may determine that the first 2
symbols are being used for control information and the remaining
symbols are being used for MBSFN signals. As a result, in the MBSFN
subframes, the femto cell may transmit unicast control information
in the first symbol (or the first 2 symbols), and transmit unicast
data with reduced power in the remaining data symbols.
Alternatively, the femto cell may determine to mute the
transmission of unicast data in the remaining data symbols. In one
configuration, the second base station may not transmit SIB 13, an
MCCH change notification, MCCH, or MTCH.
[0108] In another configuration, the second base station may
transmit unicast control information in the first set of symbols
and transmit unicast data with reduced power in the second set of
symbols. In this configuration, the second base station may also
transmit an MCCH change notification in the first set of symbols in
the MBSFN subframes and/or transmit SIB 13 in non-MBSFN subframes,
consistent with a SIB 13 and an MCCH change notification
transmitted by the first base station. For example, the first base
station may be an eNB, and the second base station may be a femto
cell. The femto cell may transmit unicast data with reduced power
in MBSFN subframes and also transmit SIB 13 on the PDSCH in
non-MBSFN subframes. The femto cell may also transmit MCCH change
notification on the PDCCH in the control symbols (e.g., the first
set of symbols) of MBSFN subframes. In this configuration, the
reception of system information and the control information by the
UE may be more robust due to the transmissions by the femto
cell.
[0109] In another configuration, the second base station may also
transmit, in MBSFN subframes, an MCCH in the second set of symbols
synchronously with the MCCH transmitted by the first base station.
For example, the first base station may be an eNB, and the second
base station may be a femto cell. The femto cell may transmit SIB
13 on the PDSCH in non-MBSFN subframes, and, in MBSFN subframes,
transmit unicast data with reduced power, an MCCH change
notification on the PDCCH in the control symbols (e.g., the first
set of symbols), and MCCH in data symbols (e.g., the second set of
symbols) synchronously with the MCCH transmitted by the eNB. In
this configuration, the MCCH has also been made more robust by the
femto cell based on the joint transmissions by the femto cell and
the eNB.
[0110] In such a method, synchronization between the first base
station and the second base station may be needed. In TDD, the
second base station may be synchronized to the first base station
(e.g., within 3 .mu.s accuracy). In FDD, the second base station
can be synchronized to the network. By listening to the network,
the second base station can synchronize certain transmissions with
the network. Thus, subframe boundaries and system frame numbers
(SFNs) of the first base station and the second base station would
be aligned.
[0111] FIG. 14A is a diagram 1400 illustrating network architecture
configured to provide MBMS service. As shown in FIG. 14A, a first
base station (e.g., the eNB) is connected to an MBMS-GW via an M1
interface. The M1 interface is the user plane interface through
which user data may be provided to the first base station from a
BM-SC through the MBMS-GW. The first base station may also be
connected to an MCE via an M2 interface. The M2 interface is a
E-UTRAN internal control plane interface through which control
information may be provided to the first base station from an MME
through the MCE. The MCE is connected to the MME through the M3
interface, which is the control plane interface between the E-TRAN
and the EPC. One method of providing MBMS service awareness to
lower power class base stations for purposes of base station
cooperation is to extend the MBMS network architecture to the lower
power class base stations as shown in FIG. 14B.
[0112] FIG. 14B is a diagram 1450 illustrating an exemplary network
architecture and method for improving MBMS coexistence in a network
with multiple types of base stations through base station
cooperation. As illustrated in FIG. 14B, lower power base stations
may cooperate with higher power base stations to improve MBMS
coexistence in a network based on received operation and management
(O&M) configurations. In FIG. 14B, a first base station (e.g.,
eNB) has a first power class, and a second base station (e.g., HeNB
or femto cell) has a second power class. The second power class may
be lower than the first power class. The first base station may be
connected to the MCE via the M2 interface and connected to the MBMS
GW via the M1 interface. Unlike in FIG. 14A, however, in FIG. 14B,
the M1 and M2 interfaces have been extended from the MBMS GW and
MCE, respectively, to the second base station. The M1 and M2
interface may be extended directly to the second base station or
indirectly to the second base station through the HeNB GW for
additional security. The second base station may be connected to
the BM-SC through a backhaul link (e.g., DSL/cable) for purposes of
receiving MBSFN data. An HeNB management system (HMS) may be used
for configuring the second base station such that the second base
station is aware of the MBSFN subframes and other MBMS
configuration information.
[0113] Referring to FIG. 14B, the first base station may be
transmitting MBSFN signals to a UE on the same frequency that the
second base station transmits unicast signals. As a result,
reception of an MBMS transmission at the UE may suffer from
interference due to the unicast transmission. In an attempt to
reduce the interference, the second base station may cooperate with
the first base station.
[0114] An MBMS session may be set up between the BM-SC and the
second base station. In one aspect, the MBMS session may be
initiated by the BM-SC. In this aspect, the BM-SC may transmit a
session start request and the second base station may transmit a
session start response to set up the MBMS session. In another
aspect, the MBMS session may be initiated by the second base
station. In this aspect, the second base station may listen for
MBSFN signals for an MBMS service from the first base station and,
upon detecting the MBSFN signals, send an MBMS session start
initiation to the BM-SC through a MCE, a MME, and a MBMS GW to
initiate an MBMS session associated with the MBMS service.
Subsequently, the second base station may receive a response to the
MBMS session start initiation for purposes of setting up an MBMS
session. In both aspects, the second base station may perform the
above steps (e.g., send an initiation message and receive a
response or receive an initiation message and send a response) to
join the same MBMS session as the first base station. Having joined
the MBMS session, the second base station may receive MBMS content
(e.g., data and/or control information) from the BM-SC via a
synchronization protocol. Also, the second base station may receive
information from the HMS. The information received from the HMS may
include information such as MBSFN configuration information, the
number of MBSFN subframes being used by the first base station, the
number of control symbols being used in an MBSFN subframe, and the
MCCH configuration, etc. Based on some or all of the information
received from the HMS, the second base station may determine the
MBSFN subframes of the first base station. The second base station
may determine the frequency at which the first base station
transmits the MBSFN signals (e.g., based on the MBSFN configuration
information). The second base station may also determine, in the
MBSFN subframes, a first set of symbols used for control
information and a second set of symbols used for MBSFN signals
(e.g., user data) by the first base station. In one aspect, the
second base station may determine the first and second set of
symbols via backhaul communication between the BM-SC and the second
base station or via backhaul communication between the first base
station and the second base station. In another aspect, the second
base station may determine the first and second symbols based on
network listening in which the second base station listens to the
MCCH transmitted by the first base station. The first set of
symbols may include one or two symbols. After this determination,
the second base station may transmit unicast control information in
a subset of the first set of symbols at the determined frequency
that the first base station transmits MBSFN signals. The second
base station may transmit unicast data at the same determined
frequency with reduced power in the second set of symbols so as to
reduce interference to the UE during MBSFN transmission. The
reduced power may be zero power such that the second base station
is effectively muting the unicast data in the second set of
symbols.
[0115] For example, the first base station may be an eNB and the
second base station may be a femto cell. The eNB may transmit MBSFN
signals to provide MBMS service to a UE. The femto cell may be
causing interference to the UE by simultaneously transmitting
unicast signals on the same frequency that the eNB is transmitting
MBSFN signals. To reduce interference, the femto cell may cooperate
with the eNB. In one example, an MBMS session may be set up (or
initiated) between a BM-SC and the femto cell. In another example,
the femto cell may listen for MBSFN signals, and upon the detection
of MBSFN signals, send an MBMS session start initiation to the
BM-SC through an MCE, an MME, and an MBMS GW to initiate an MBMS
session. Once the MBMS session is initiated, the femto cell may
receive information from the HMS, and such information may include
MBSFN configuration information (e.g., a frequency at which the
MBSFN signals are transmitted by the eNB). Based on the received
information from the HMS, the femto cell may determine which MBSFN
subframes are being used by the eNB for MBSFN signal transmission.
In those MBSFN subframes, the femto cell may determine that 2
symbols are being used for control information and the remaining
symbols are being used for MBSFN signals. As a result, the femto
cell may transmit unicast control information in a subset of the 2
symbols (e.g., on the first symbol), and transmit unicast data with
reduced power in the remaining data symbols. In an aspect, the
unicast control information and the unicast data may be transmitted
at the frequency of the MBSFN signals. Alternatively, the femto
cell may determine to mute the transmission of unicast data in the
remaining data symbols.
[0116] In one configuration, the second base station may also
transmit SIB 13 in non-MBSFN subframes and/or transmit an MCCH
change notification in the first set of symbols in MBSFN subframes,
consistent with a SIB 13 and/or an MCCH change notification
transmitted by the first base station. For example, in this
configuration, the first base station may be an eNB and the second
base station may be a femto cell. In the MBSFN subframes, the femto
cell may transmit unicast data on reduced power. The femto cell may
transmit MCCH change notification on the PDCCH in the controls
symbols (e.g., the first set of symbols) of the MBSFN subframe. The
femto cell may transmit SIB 13 on the PDSCH in non-MBSFN
subframes.
[0117] In another configuration, the second base station may also
transmit an MCCH in the second set of symbols synchronously with
the MCCH transmitted by the first base station. The second base
station may obtain the MCCH from the BM-SC or by listening to the
MCCH from the first base station. Because the second base station
transmits the MCCH synchronously with the MCCH of the first base
station, the second base station may transmit the MCCH on the same
symbol(s) and subcarrier(s) as used by the first base station. The
second base station may determine the symbol(s) and subcarrier(s)
used by the first base station for transmitting MCCH based on
backhaul communication with the BM-SC or the first base station or
via network listening for the MCCH. For example, in this
configuration, the first base station may be an eNB and the second
base station may be a femto cell. The femto cell may transmit SIB
13 on the PDSCH in non-MBSFN subframes, and in MBSFN subframes,
transmit unicast data on reduced power, MCCH change notification on
the PDCCH in the control symbols (e.g., the first set of symbols),
and MCCH in the data symbols (e.g., the second set of symbols). The
femto cell may transmit the MCCH synchronously with the MCCH
transmitted by the eNB.
[0118] In another configuration, the second base station may also
transmit MTCH in the second set of symbols synchronously with the
MTCH transmitted by the first base station. The second base station
may obtain the MTCH from the BM-SC. For example, in this
configuration, the first base station may be an eNB and the second
base station may be femto cell. Also, the first set of symbols may
be referred to as control symbols for transmitting control
information and the second set of symbols may be referred to as
data symbols for transmitting MBSFN data. The femto cell may
transmit SIB 13 on the PDSCH in non-MBSFN subframes. In MBSFN
subframes, the femto cell may transmit MCCH change notification on
the PDCCH in the control symbols, transmit MCCH in data symbols
synchronously with the MCCH transmitted by the eNB, and/or transmit
MTCH in data symbols synchronously with the MTCH transmitted by the
eNB. In this configuration, the second base station (e.g., femto
cell) is functioning like the first base station (e.g., eNB)
because the second base station is able to transmit MBSFN control
signals via information received from the M2 interface as well as
user data received from the M1 interface. Thus, by participating in
the transmission of either MBSFN control information and/or MBSFN
data to the UE, the second base station may increase the likelihood
that the UE can successfully receive MBMS service.
[0119] FIG. 15 is a flow chart 1500 of an exemplary method of
improving MBMS coexistence in a network with multiple types of base
stations. The method may be performed by a second base station
(e.g., femto cell, pico cell, relay node) having a second power
class. At block 1502, the second base station may listen for MBSFN
signals for MBMS service from a first base station (e.g., an eNB)
having a first power class. The second power class may be lower
than the first power class. Upon detecting the MBSFN signals, the
second base station may send an MBMS session start initiation to
the BM-SC through an MCE, an MME, and an MBMS GW. In response to
the MBMS session start initiation, the BM-SC may set up an MBMS
session with the second base station following existing MBMS setup
procedures. For example, the first base station may be an eNB and
the second base station may be a femto cell. The femto cell may
detect MBSFN signals for MBMS service from the eNB. Upon detecting
the MBSFN signals, the femto cell may send an MBMS session start
initiation to the BM-SC through an MCE, an MME, and an MBMS GW. In
response, the BM-SC may set up an MBMS session with the femto cell
following existing MBMS setup procedures. In another configuration,
however, the MBMS session may be initiated by the BM-SC.
[0120] At block 1504, the second base station may initiate or join
an MBMS session associated with a BM-SC. For example, the second
base station may be a femto cell. The femto cell may initiate an
MBMS session with a BM-SC by sending an MBMS session start
initiation message to initiate the MBMS session. In another
example, the BM-SC may initiate an MBMS session, and the femto cell
may join the MBMS session. In both examples, an MBMS session is set
up between the BM-SC and the femto cell.
[0121] At block 1506, the second base station may receive
information from the HMS. The information received from the HMS may
include information such as MBSFN configuration information, the
number of MBSFN subframes being used by the first base station, the
number of control symbols being used in an MBSFN subframe, and the
MCCH configuration, etc.
[0122] At block 1508, based on the information received from the
HMS, the second base station may determine the MBSFN subframes
transmitted by the first base station. The second base station may
also determine, in the MBSFN subframes, a first set of symbols used
for control information and a second set of symbols used for MBSFN
signals (e.g., user data) by the first base station. In particular,
the second base station may determine resources (e.g., determine
specific symbols and subcarriers) used by the first base station
for transmitting MCCH. The second base station may determine
additional resources (e.g., determine specific symbols and
subcarriers) used by the first base station for transmitting MTCH.
For example, the first base station may be an eNB and the second
base station may be a femto cell. In this example, based on the
received information from the HMS, the femto cell may determine
which MBSFN subframes are being used by the eNB for MBSFN signal
transmission. In those MBSFN subframes, the femto cell may
determine that 2 symbols are being used for control information and
the remaining data symbols are being used for MBSFN signals. More
specifically, the femto cell may determine the symbols and
subcarriers used by the eNB for transmitting MCCH and/or MTCH.
[0123] At block 1510, the second base station may transmit unicast
control information in a subset of the first set of symbols. The
second base station may transmit unicast data with reduced power in
the second set of symbols so as to reduce interference with the
MBSFN transmission at the UE. The reduced power may be zero power
such that the second base station is effectively muting the unicast
data in the second set of symbols. For example, the first base
station may be an eNB, and the second base station may be a femto
cell. The femto cell may transmit unicast control information in a
subset of the 2 symbols (e.g., on the first symbol or the first 2
symbols), and transmit unicast data with reduced power in the
remaining data symbols. Alternatively, the femto cell may determine
to mute the transmission of unicast data in the remaining data
symbols.
[0124] At block 1512, the second base station may transmit at least
one of a SIB 13 in non-MBSFN subframes, an MCCH change notification
in the first set of symbols, an MCCH in the second set of symbols,
and/or an MTCH in the second set of symbols. For example, the
second base station may be a femto cell. The femto cell may
transmit a SIB 13 in non-MBSFN subframes and an MCCH change
notification in the first set of symbols.
[0125] FIG. 16 is a diagram 1600 illustrating an exemplary network
architecture and method for improving MBMS coexistence in a network
with multiple types of base stations through base station
cooperation. In FIG. 16, a first base station (e.g., eNB) has a
first power class, and a second base station (e.g., HeNB) has a
second power class. The second power class may be lower than the
first power class. The first base station may be connected to the
MCE via the M2 interface and connected to the MBMS GW via the M1
interface. The second base station may be directly connected to the
MBMS GW via the M1 interface and/or indirectly connected to the
MGMS GW through the HeNB GW. However, the second base station is
not connected to the MCE via an M2 interface. The first base
station may be transmitting MBSFN signals to the UE on the same
frequency that the second base station is transmitting unicast
signals. As a result, the UE may suffer from interference as a
result of the unicast transmission. In an attempt to reduce the
interference, the second base station may cooperate with the first
base station.
[0126] In FIG. 16, unlike in FIG. 14B, the second base station is
not connected to the MCE via an M2 interface. As a result, the
second base station cannot cooperate with the first base station
based on MBSFN configuration information received directly from the
MCE. Nevertheless, the second base station may cooperate with the
first base station through network listening. The second base
station may receive user service description (USD) bootstrapping
information. The USD bootstrapping information may be received from
the network or may be preconfigured. Based on the USD bootstrapping
information, the second base station may obtain or receive a USD
via a unicast transmission or via an MBMS session. For example, to
receive the USD via unicast, the second base station may be
preconfigured with a unicast server IP address or an URL and fetch
the USD through a unicast channel from a server. Alternatively, to
receive the USD via MBMS transmission, the second base station may
receive or be preconfigured with the USD bootstrapping information.
The USD bootstrapping information may provide the specific TMGI
associated with the USD, and the second base station may use the
specific TMGI to listen to the MBMS transmission to obtain the USD
from an MBMS bearer. The USD may contain a session description
protocol (SDP) associated with an MBMS session. The SDP may include
a multicast IP address and a sender source IP address associated
with an MBMS session. Thus, after obtaining the USD, the second
base station may obtain the multicast IP address and the source IP
address from the USD (e.g., from the SDP in the USD). With the
multicast IP address and the source IP address, the second base
station may join the multicast tree from the first base station.
After joining the multicast tree, the second base station may
perform network listening and receive a SIB 2 from the first base
station. The second base station may receive an MSI from the first
base station. The second base station may receive SIB 13 from the
first base station. The second base station may obtain the MBSFN
configuration based on the received SIB 13. The second base station
may also obtain an MCCH based on the received SIB 13. The second
base station may obtain the MBSFN configuration based on the
obtained MCCH and the SIB 13. The MBSFN configuration would have
information on the MBSFN subframes of the first base station. The
second base station may also determine the MBSFN subframes of the
first base station based on the received SIB 2 and/or the received
MSI. MSI may have more accurate information regarding MBSFN
subframes used for MBMS compared to MCCH, SIB 13, and SIB 2.
[0127] Having determined the MBSFN subframes of the first base
station, the second base station may determine, in the MBSFN
subframes, a first set of symbols used for control information by
the first base station and a second set of symbols used for MBSFN
signals (e.g., user data) by the first base station. The first set
of symbols may include one or two symbols. The second base station
may determine the first and second set of symbols used for control
information and for MBSFN signals, respectively, based on the MCCH
received through network listening. The MCCH (and/or SIB 13) may
also indicate specific symbols and/or subcarriers used by the first
base station for transmitting MCCH and/or MTCH. After this
determination, the second base station may transmit unicast control
information in a subset of the first set of symbols. The second
base station may transmit unicast data with reduced power in the
second set of symbols so as to reduce interference to the UE during
MBSFN transmission. The reduced power may be zero power such that
the second base station is effectively muting the unicast data in
the second set of symbols. For example, the first base station may
be an eNB and the second base station may be a femto cell. The eNB
may transmit on MBSFN signals to provide MBMS service to a UE. The
femto cell may be causing interference to the UE by simultaneously
transmitting unicast signals on the same frequency that the eNB is
transmitting MBSFN signals. To reduce interference, the femto cell
may cooperate with the eNB by performing network listening. The
femto cell may be preconfigured with or may receive from the
network USD bootstrapping information. Based on the USD
bootstrapping information, the femto cell may obtain or receive a
USD from unicast or MBMS via the eNB. After obtaining the USD, the
femto cell may obtain a multicast IP address and a source IP
address from the USD. With the multicast IP address and source IP
address, the femto cell may join the multicast tree from the eNB.
After joining the multicast tree, the femto cell may perform
network listening and receive a SIB 2, MSI, and SIB 13 from the
eNB. The femto cell may obtain MCCH based on the received SIB 13.
The femto cell may obtain the MBSFN configuration based on the
obtained MCCH and the SIB 13, and the MBSFN configuration would
have information on the MBSFN subframes being used by the eNB. The
femto cell may also determine the MBSFN subframes based on the
received SIB 2 and/or the received MSI.
[0128] Having determined the MBSFN subframes of the eNB, the femto
cell may determine, in the MBSFN subframes, a first set of symbols
used for control information by the eNB and a second set of symbols
used for MBSFN signals (e.g., user data) by the eNB. The femto cell
may determine that 2 symbols are being used for control information
and the remaining data symbols are being used for MBSFN signals.
The femto cell may also determine the subcarriers in the symbols
used by the first base station for transmitting MCCH and/or MTCH.
As a result, in the MBSFN subframes, the femto cell may transmit
unicast control information in a subset of the two symbols (e.g.,
the first two symbols), and transmit unicast data with reduced
power in the remaining data symbols. Alternatively, the femto cell
may determine to mute the transmission of unicast data in the
remaining data symbols.
[0129] In one configuration, the second base station may also
transmit SIB 13 in non-MBSFN subframes. In MBSFN subframes, the
second base station may transmit an MCCH change notification in the
first set of symbols. The SIB 13 and the MCCH change notification
may be transmitted with a SIB 13 and an MCCH change notification
transmitted by the first base station. In this configuration, the
second base station may transmit via unicast the same SIB 13 and
MCCH change notification content as the first base station.
However, the resources used by the second base station to transmit
the SIB 13 and MCCH change notification need not be the same
resources used by the first base station for transmitting the SIB
13 and MCCH change notification. For example, in this
configuration, the first base station may be an eNB and the second
base station may be a femto cell. The femto cell may transmit
unicast data with reduced power in the MBSFN subframes. The femto
cell may also transmit SIB 13 on the PDSCH in non-MBSFN subframes
and/or an MCCH change notification on the PDCCH in the first 2
symbols in the MBSFN subframes. In an aspect, the resources used by
the femto cell to transmit the SIB 13 and MCCH change notification
need not be the same resources used by the eNB for transmitting the
SIB 13 and MCCH change notification.
[0130] In another configuration, the second base station may also
transmit an MCCH in the second set of symbols synchronously with
the MCCH transmitted by the first base station. In this
configuration, the second base station may determine the resources
within the second set of symbols used by the first base station for
transmitting the MCCH. The resources may include the data symbol(s)
and the sub-carrier(s) within the MBSFN subframe used by the first
base station for transmitting the MCCH. For example, the first base
station may be an eNB, and the second base station may be a femto
cell. The femto cell may transmit unicast data on reduced power in
the MBSFN subframes. The femto cell may transmit an MCCH change
notification on the PDCCH in the first 2 symbols of the MBSFN
subframes. The femto cell may determine the data symbols (e.g., the
second set of symbols) and the corresponding sub-carriers of the
MBSFN subframes that the eNB uses for transmitting the MCCH. The
femto cell may transmit MCCH in data symbols of the MBSFN subframes
synchronously (e.g., in the same data symbols and the same
sub-carriers) with the MCCH transmitted by the eNB. The femto cell
may transmit SIB 13 on the PDSCH in non-MBSFN subframes.
[0131] In another configuration, having joined the multicast group
upon receiving MBSFN configuration and having an M1 interface with
the MBMS GW to receive MBMS content, the second base station may
also transmit MTCH in the second set of symbols synchronously with
the MTCH transmitted by the first base station. In one aspect, the
MTCH may be transmitted by the second based station based on the
obtained MBSFN configuration and the M1 interface with the MBMS GW.
In this configuration, the second base station may determine
additional resources within the second set of symbols used by the
first base station for transmitting the MTCH. The additional
resources may include the data symbol(s) and the sub-carrier(s)
within the MBSFN subframe used by the first base station for
transmitting the MTCH. For example, the first base station may be
an eNB, and the second base station may be a femto cell. The femto
cell may transmit unicast data on reduced power in MBSFN subframes.
The femto cell may determine the data symbols and the corresponding
sub-carriers of the MBSFN subframes that the eNB uses for
transmitting the MTCH. The femto cell may also transmit MCCH change
notification on the PDCCH in the first 2 symbols of the MBSFN
subframes, transmit an MCCH in data symbols synchronously (e.g., in
the same data symbols and the same sub-carriers as used by the eNB)
with the MCCH transmitted by the eNB, and transmit an MTCH in data
symbols synchronously (e.g., in the same data symbols and the same
sub-carriers as used by the eNB) with the MTCH transmitted by the
eNB. The femto cell may transmit SIB 13 on the PDSCH in non-MBSFN
subframes. In this configuration, the femto cell is functioning
like the eNB because the femto cell is able to transmit MBSFN
control signals and data upon joining the multicast group/tree.
Thus, by participating in the transmission of either MBSFN control
information and/or data to the UE, the femto cell may increase the
likelihood that the UE can successfully receive MBMS service.
Furthermore, by receiving the MBSFN configuration through network
listening, dynamic changes in the MBSFN configuration may be easily
detected.
[0132] FIG. 17 is a flow chart 1700 of an exemplary method of
improving MBMS coexistence in a network with multiple types of base
stations. The method may be performed by a second base station
(e.g., femto cell, pico cell, relay node) having a second power
class. At block 1702, the second base station may receive user
service description (USD) bootstrapping information. The USD
bootstrapping information may be received from the network or be
preconfigured. For example, the second base station may be a femto
cell. The femto cell may be preconfigured with or may receive from
the network USD bootstrapping information.
[0133] At block 1704, based on the USD bootstrapping information,
the second base station may obtain or receive a USD from via a
unicast transmission or an MBMS service. After obtaining the USD,
the second base station may obtain a multicast IP address and a
source IP address from the USD. With the multicast IP address and
the source IP address, the second base station may join the
multicast tree from the first base station. For example, the first
base station may be an eNB, and the second base station may be a
femto cell. Based on the USD bootstrapping information, the femto
cell may obtain or receive a USD from unicast or MBMS via the eNB.
After obtaining the USD, the femto cell may obtain a multicast IP
address and a source IP address from the USD. With the multicast IP
address and source IP address, the femto cell may join the
multicast tree from the eNB.
[0134] At block 1706, the second base station may perform network
listening and receive a SIB 2 from the first base station. The
second base station may determine the MBSFN subframes based on the
received SIB 2. For example, the first base station may be an eNB
and the second base station may be a femto cell. The femto cell may
receive a SIB 2 from the eNB.
[0135] At block 1708, the second base station may receive an MSI
from the first base station. The second base station may determine
the MBSFN subframes based on the received MSI. For example, the
first base station may be an eNB and the second base station may be
a femto cell. The femto cell may receive an MSI from the eNB.
[0136] At block 1710, the second base station may receive SIB 13
from the first base station. For example, the first base station
may be an eNB and the second base station may be a femto cell. The
femto cell may receive a SIB 13 from the eNB.
[0137] At block 1712, the second base station may obtain the MBSFN
configuration based on the received SIB 13. The second base station
may also obtain an MCCH based on the received SIB 13. The second
base station may obtain the MBSFN configuration based on the
obtained MCCH and the SIB 13. The MBSFN configuration would have
information on the MBSFN subframes of the first base station. For
example, the first base station may be an eNB and the second base
station may be a femto cell. The femto cell may obtain the MCCH
based on the received SIB 13. The femto cell may obtain the MBSFN
configuration based on the obtained MCCH and the SIB 13, and the
MBSFN configuration would have information on the MBSFN subframes
being used by the eNB. The femto cell may also determine the MBSFN
subframes based on the received SIB 2 and/or the received MSI.
[0138] At block 1714, the second base station may determine, in the
MBSFN subframes, a first set of symbols used for control
information and a second set of symbols used for MBSFN signals
(e.g., user data) by the first base station. For example, the first
base station may be an eNB and the second base station may be a
femto cell. The femto cell may determine, in the MBSFN subframes, a
first set of symbols used for control information and a second set
of symbols used for MBSFN signals (e.g., user data). The femto cell
may determine the MBSFN subframes used by the eNB based on an MCCH
(and/or SIB 13) received from the eNB. And the femto cell may
determine the first set of symbols used for control information and
the second set of symbols used for MBSFN signals based on the MCCH
(and/or SIB 13) received from the eNB. In particular, the MCCH may
indicate resources (e.g., data symbols and subcarriers) within the
second set of symbols used for MBSFN signals (e.g., for
transmitting MTCH). The femto cell may determine that 2 symbols are
being used for control information and the remaining symbols are
being used for MBSFN signals.
[0139] At block 1716, the second base station may determine
resources within the second set of symbols used by the first base
station for transmitting an MCCH. The second base station may also
determine additional resources within the second set of symbols
used by the first base station for transmitting an MTCH. For
example, the first base station may be an eNB and the second base
station may be a femto cell. The femto cell may determine the
symbols and sub-carriers within the second set of symbols used by
the eNB for transmitting the MCCH based on an MCCH or SIB 13
received from the eNB. The femto cell may also determine the
symbols and sub-carriers within the second set of symbols used by
the eNB for transmitting the MTCH based on an MCCH received from
the eNB. As discussed above, the femto cell may obtain the MCCH
from the eNB based on a received SIB 13, and the MCCH may indicate
the resources (e.g., symbols and subcarriers) on which the MCCH is
transmitted by the eNB and may indicate the additional resources on
which the MTCH is transmitted by the eNB.
[0140] At block 1718, the second base station may transmit unicast
control information in a subset of the first set of symbols. The
unicast control information may be transmitted at a frequency that
the first base station is using for providing MBMS service. The
second base station may transmit unicast data with reduced power in
the second set of symbols so as to reduce interference to the UE
during MBSFN transmission. The unicast data may be transmitted at a
frequency that the first base station is using for providing MBMS
service. The reduced power may be zero power such that the second
base station is effectively muting the unicast data in the second
set of symbols. For example, the first base station may be an eNB,
and the second base station may be a femto cell. In an MBSFN
subframe, the femto cell may transmit unicast control information
in a subset of the two symbols (e.g., the first two symbols), and
transmit unicast data with reduced power in the remaining data
symbols. Alternatively, the femto cell may determine to mute the
transmission of unicast data in the remaining data symbols.
[0141] At block 1720, the second base station may transmit, at the
frequency at which the first base station is transmitting MBSFN
signals, at least one of a SIB 13 in non-MBSFN subframes, an MCCH
change notification in the first set of symbols, an MCCH in the
second set of symbols, or an MTCH in the second set of symbols. For
example, the first base station may be an eNB, and the second base
station may be a femto cell. The femto cell may transmit SIB 13 on
the PDSCH in non-MBSFN subframes, and in MBSFN subframes, transmit
unicast data on reduced power, transmit an MCCH change notification
on PDCCH in the first 2 symbols of the MBSFN subframes, and
transmit an MCCH in data symbols synchronously (e.g., within the
same data symbols and sub-carriers as the eNB) with the MCCH
transmitted by the eNB.
[0142] FIG. 18 is a conceptual data flow diagram 1800 illustrating
the data flow between different modules/means/components in an
exemplary apparatus 1802. The apparatus may be a UE. The apparatus
includes an RRC state module 1806 that may be configured to
maintain an RRC idle state with the first base station 1812. The
apparatus includes a reception module 1804 that may be configured
to determine that the UE is in range of the second base station
1814. The second base station 1814 may have a second power class.
The RRC state module 1806 may be configured to establish an RRC
connected state with a first base station 1812. The first base
station 1812 may have a first power class, and the first power
class may be greater than the second power class. The RRC state
module 1806 may be configured to establish an RRC connected state
with the first base station 1812 through the transmission module
1810. The RRC state module 1806 may be configured to move in a
handoff from the first base station 1812 to the second base station
1814 upon determining that the UE is in range of the second base
station 1814. The reception module 1804 and transmission module
1810 may be configured to communicate with a second base station
1814 in an RRC connected state. The reception module 1804 may be
configured to receive MBMS service from a first base station 1812
while in an RRC connected state with the second base station 1814.
The apparatus includes a decode module 1808 that may be configured
to determine that the apparatus is unable to decode MBSFN signals
of the MBMS service from the first base station 1812. The reception
module 1804 may be configured to receive the MBMS service from the
second base station 1814 through a unicast channel upon determining
that the apparatus is unable to decode the MBSFN signals of the
MBMS service from the first base station 1812.
[0143] The apparatus may include additional modules that perform
each of the blocks of the algorithm in the aforementioned flow
charts of FIG. 9. As such, each block in the aforementioned flow
charts of FIG. 9 may be performed by a module and the apparatus may
include one or more of those modules. The modules may be one or
more hardware components specifically configured to carry out the
stated processes/algorithm, implemented by a processor configured
to perform the stated processes/algorithm, stored within a
computer-readable medium for implementation by a processor, or some
combination thereof.
[0144] FIG. 19 is a diagram 1900 illustrating an example of a
hardware implementation for an apparatus 1802' employing a
processing system 1914. The processing system 1914 may be
implemented with a bus architecture, represented generally by the
bus 1924. The bus 1924 may include any number of interconnecting
buses and bridges depending on the specific application of the
processing system 1914 and the overall design constraints. The bus
1924 links together various circuits including one or more
processors and/or hardware modules, represented by the processor
1904, the reception module 1804, the RRC state module 1806, the
decode module 1808, the transmission module 1810, and the
computer-readable medium/memory 1906. The bus 1924 may also link
various other circuits such as timing sources, peripherals, voltage
regulators, and power management circuits, which are well known in
the art, and therefore, will not be described any further.
[0145] The processing system 1914 may be coupled to a transceiver
1910. The transceiver 1910 is coupled to one or more antennas 1920.
The transceiver 1910 provides a means for communicating with
various other apparatus over a transmission medium. The transceiver
1910 receives a signal from the one or more antennas 1920, extracts
information from the received signal, and provides the extracted
information to the processing system 1914, specifically the
reception module 1804. In addition, the transceiver 1910 receives
information from the processing system 1914, specifically the
transmission module 1810, and based on the received information,
generates a signal to be applied to the one or more antennas 1920.
The processing system 1914 includes a processor 1904 coupled to a
computer-readable medium/memory 1906. The processor 1904 is
responsible for general processing, including the execution of
software stored on the computer-readable medium/memory 1906. The
software, when executed by the processor 1904, causes the
processing system 1914 to perform the various functions described
supra for any particular apparatus. The computer-readable
medium/memory 1906 may also be used for storing data that is
manipulated by the processor 1904 when executing software. The
processing system further includes at least one of the modules
1804, 1806, 1808, and 1810. The modules may be software modules
running in the processor 1904, resident/stored in the computer
readable medium/memory 1906, one or more hardware modules coupled
to the processor 1904, or some combination thereof. The processing
system 1914 may be a component of the UE 650 and may include the
memory 660 and/or at least one of the TX processor 668, the RX
processor 656, and the controller/processor 659.
[0146] In one configuration, the apparatus 1802/1802' for wireless
communication includes means for communicating with a second base
station in an RRC connected state. The apparatus 1802/1802' may
include means for receiving an MBMS service from a first base
station while in an RRC connected state with the second base
station. The first base station has a first power class, and the
second base station has a second power class lower than the first
power class. The apparatus may include means for determining that
the apparatus is unable to decode MBSFN signals of the MBMS service
from the first base station. For example, the signal to noise ratio
from the first base station may be below a threshold, or the block
error rate may be too high. The apparatus may include means for
receiving the MBMS service from the second base station through a
unicast channel upon determining that the apparatus is unable to
decode the MBSFN signals of the MBMS service from the first base
station. The apparatus may include means for maintaining an RRC
idle state with the first base station. The apparatus may include
means for determining that the apparatus is in range of the second
base station. For example, the apparatus may detect signals from
the second base station. The apparatus may include means for
establishing an RRC connected state with the first base station.
The apparatus may include means for moving in a handoff from the
first base station to the second base station upon determining that
the UE is in range of the second base station.
[0147] The aforementioned means may be one or more of the
aforementioned modules of the apparatus 1802 and/or the processing
system 1914 of the apparatus 1802' configured to perform the
functions recited by the aforementioned means. As described supra,
the processing system 1914 may include the TX Processor 668, the RX
Processor 656, and the controller/processor 659. As such, in one
configuration, the aforementioned means may be the TX Processor
668, the RX Processor 656, and the controller/processor 659
configured to perform the functions recited by the aforementioned
means.
[0148] FIG. 20 is a conceptual data flow diagram 2000 illustrating
the data flow between different modules/means/components in an
exemplary apparatus 2002. The apparatus may be a UE. The apparatus
includes a reception module 2004 that may be configured to receive
a composite signal that includes a MBSFN signal from a first base
station 2012 and a unicast interfering signal from a second base
station 2014. The first base station 2012 has a first power class.
The second base station 2014 has a second power class. The second
power class may be lower than the first power class. The apparatus
includes a conversion/subtraction module 2008 that may be
configured to convert the received composite signal from a time
domain to a frequency domain (e.g., by performing an FFT). The
apparatus includes an estimation module 2006 that may be configured
to estimate the unicast interfering signal from the frequency
domain converted signal. The conversion/subtraction module 2008 may
be configured to convert the estimated unicast interfering signal
into a time domain interfering signal (e.g., by performing
IFFT).
[0149] In one configuration, the first base station 2012 transmits
symbols with an extended cyclic prefix, the second base station
2014 transmits symbols with a normal cyclic prefix, the
conversion/subtraction module 2008 may be configured to convert the
estimated unicast interfering signal into a set of symbols in the
time domain. The conversion/subtraction module 2008 may also be
configured to append a normal cyclic prefix to each symbol. The
conversion/subtraction module 2008 may also be configured to append
two or more cyclic prefix appended symbols together to obtain the
time domain interfering signal.
[0150] In another configuration, the first base station 2012
transmits symbols with a normal cyclic prefix, the second base
station 2014 transmits symbols with an extended cyclic prefix, the
conversion/subtraction module 2008 may be configured to convert the
estimated unicast interfering signal into a set of symbols in the
time domain. The conversion/subtraction module 2008 may also be
configured to append an extended cyclic prefix to each symbol. The
conversion/subtraction module 2008 may also be configured to append
one or more cyclic prefix appended symbols together to obtain the
time domain interfering signal.
[0151] The conversion/subtraction module 2008 may be configured to
subtract the time domain interfering signal from the received
composite signal to obtain an interference reduced signal. The
apparatus may include a decode module 2010 that may be configured
to decode the interference reduced signal to obtain an MBSFN
transmission.
[0152] The apparatus may include additional modules that perform
each of the blocks of the algorithm in the aforementioned flow
charts of FIGS. 11 and 12. As such, each block in the
aforementioned flow charts of FIGS. 11 and 12 may be performed by a
module and the apparatus may include one or more of those modules.
The modules may be one or more hardware components specifically
configured to carry out the stated processes/algorithm, implemented
by a processor configured to perform the stated
processes/algorithm, stored within a computer-readable medium for
implementation by a processor, or some combination thereof.
[0153] FIG. 21 is a diagram 2100 illustrating an example of a
hardware implementation for an apparatus 2002' employing a
processing system 2114. The processing system 2114 may be
implemented with a bus architecture, represented generally by the
bus 2124. The bus 2124 may include any number of interconnecting
buses and bridges depending on the specific application of the
processing system 2114 and the overall design constraints. The bus
2124 links together various circuits including one or more
processors and/or hardware modules, represented by the processor
2104, the reception module 2004, the estimation module 2006, the
conversion/subtraction module 2008, the decode module 2010, and the
computer-readable medium/memory 2106. The bus 2124 may also link
various other circuits such as timing sources, peripherals, voltage
regulators, and power management circuits, which are well known in
the art, and therefore, will not be described any further.
[0154] The processing system 2114 may be coupled to a transceiver
2110. The transceiver 2110 is coupled to one or more antennas 2120.
The transceiver 2110 provides a means for communicating with
various other apparatus over a transmission medium. The transceiver
2110 receives a signal from the one or more antennas 2120, extracts
information from the received signal, and provides the extracted
information to the processing system 2114, specifically the
reception module 2004. In addition, the transceiver 2110 receives
information from the processing system 2114, and based on the
received information, generates a signal to be applied to the one
or more antennas 2120. The processing system 2114 includes a
processor 2104 coupled to a computer-readable medium/memory 2106.
The processor 2104 is responsible for general processing, including
the execution of software stored on the computer-readable
medium/memory 2106. The software, when executed by the processor
2104, causes the processing system 2114 to perform the various
functions described supra for any particular apparatus. The
computer-readable medium/memory 2106 may also be used for storing
data that is manipulated by the processor 2104 when executing
software. The processing system further includes at least one of
the modules 2004, 2006, 2008, and 2010. The modules may be software
modules running in the processor 2104, resident/stored in the
computer readable medium/memory 2106, one or more hardware modules
coupled to the processor 1304, or some combination thereof. The
processing system 2114 may be a component of the UE 650 and may
include the memory 660 and/or at least one of the TX processor 668,
the RX processor 656, and the controller/processor 659.
[0155] In one configuration, the apparatus 2002/2002' for wireless
communication includes means for receiving a composite signal
including an MBSFN signal from a first base station and a unicast
interfering signal from a second base station. The first base
station has a first power class, and the second base station has a
second power class that is lower than the first power class. The
apparatus may include means for converting the received composite
signal from a time domain to a frequency domain. The apparatus may
include means for estimating the unicast interfering signal from
the frequency domain converted signal. The apparatus may include
means for converting the estimated unicast interfering signal into
a time domain interfering signal. The apparatus may include means
for subtracting the time domain interfering signal from the
received composite signal to obtain an interference reduced signal.
The apparatus may include means for decoding the interference
reduced signal to obtain an MBSFN transmission.
[0156] In one configuration, when the first base station transmits
symbols with an extended cyclic prefix, and the second base station
transmits symbols with a normal cyclic prefix, the means for
converting the estimated unicast interfering signal may be
configured to convert the estimated unicast interfering signal into
a set of symbols in the time domain, append a normal cyclic prefix
to each symbol, and append two or more cyclic prefix appended
symbols together to obtain the time domain interfering signal.
[0157] In another configuration, when the first base station
transmits symbols with a normal cyclic prefix, and the second base
station transmits symbols with an extended cyclic prefix, the means
for converting the estimated unicast interfering signal may be
configured to convert the estimated unicast interfering signal into
a set of symbols in the time domain, append a normal cyclic prefix
to each symbol, and append two or more cyclic prefix appended
symbols together to obtain the time domain interfering signal.
[0158] The aforementioned means may be one or more of the
aforementioned modules of the apparatus 2002 and/or the processing
system 2114 of the apparatus 2002' configured to perform the
functions recited by the aforementioned means. As described supra,
the processing system 2114 may include the TX Processor 668, the RX
Processor 656, and the controller/processor 659. As such, in one
configuration, the aforementioned means may be the TX Processor
668, the RX Processor 656, and the controller/processor 659
configured to perform the functions recited by the aforementioned
means.
[0159] FIG. 22 is a conceptual data flow diagram 2200 illustrating
the data flow between different modules/means/components in an
exemplary apparatus 2202. The apparatus may be a base station
(e.g., a femto cell). The apparatus includes a reception module
2204, an MBSFN configuration module 2206, an MBMS session control
module 2208, and a transmission module 2210. The MBSFN
configuration module 2206 may be configured to determine MBSFN
subframes at a frequency of a first base station. The first base
station has a first power class, and the apparatus has a second
power class. The second power class may be lower than the first
power class. The MBSFN configuration module 2206 may be configured
to determine, in the MBSFN subframes, a first set of symbols used
for control information by the first base station and a second set
of symbols used for MBSFN signals by the first base station. The
transmission module 2210 may be configured to transmit, at the
frequency, unicast control information in a subset of the first set
of symbols. The transmission module 2210 may be configured
transmit, at the frequency, unicast data with a reduced power in
the second set of symbols. The transmission module 2210 may be
configured to transmit, at the frequency, SIB 13 in non-MBSFN
subframes and an MCCH change notification in the first set of
symbols with a SIB 13 and an MCCH change notification transmitted
by the first base station. The MBSFN configuration module 2206 may
be configured to determine resources within the second set of
symbols used by the first base station for transmitting the MCCH.
The MBSFN configuration module 2206 may be configured to determine
additional resources within the second set of symbols used by the
first base station for transmitting the MTCH. The transmission
module 2210 may be configured to transmit, synchronously with the
first base station at the frequency, the MCCH in the second set of
symbols synchronously (e.g., within the determined resources) with
the MCCH transmitted by the first base station. The transmission
module 2210 may be configured to transmit, synchronously with the
first base station at the frequency, the MTCH in the second set of
symbols synchronously (e.g., within the determined additional
resources) with the MTCH transmitted by the first base station.
[0160] In one configuration, the MBMS session control module 2208
may be configured to join an MBMS session associated with a BM-SC.
In this configuration, the apparatus may have an M1 interface with
an MBMS gateway and an M2 interface with an MCE.
[0161] In another configuration, the reception module 2204 may be
configured to receive USD bootstrapping information, the MBSFN
configuration module 2206 may be configured to obtain a USD based
on the USD bootstrapping information and a multicast IP address and
a source IP address from the USD, in which the SIB 13, MCCH change
notification, MCCH, and MTCH is based on the obtained multicast IP
address and the obtained source IP address. In this configuration,
the apparatus may have an M1 interface with an MBMS gateway.
[0162] In another configuration, the transmission module 2210 may
be configured to send an MBMS session start initiation to a BM-SC
through the MCE, the MME, and the MBMS gateway, and the MBMS
session control module 2208 may be configured to initiate an MBMS
session with the BM-SC. In this configuration, the apparatus may
have an M1 interface with an MBMS gateway and an M2 interface with
an MCE.
[0163] In another configuration, the reception module 2204 may be
configured to receive information from an HMS, in which the MBSFN
subframes of the first base station are determined based on the
information received from the HMS. The information from the HMS may
indicate an MBSFN configuration. The transmission module 2210 may
be configured to transmit, based on the MBSFN configuration, at
least one of a SIB 13, an MCCH change notification, an MCCH
synchronously with the first base station at the frequency, or an
MTCH synchronously with the first base station at the
frequency.
[0164] In another configuration, the reception module 2204 may be
configured to receive a SIB 2 from the first base station, in which
the MBSFN subframes are determined based on the received SIB 2. In
another configuration, the reception module 2204 may be configured
to receive MSI, in which the MBSFN subframes are further determined
based on the received MSI.
[0165] In another configuration, the reception module 2204 may be
configured to receive a SIB 13 from the first base station. The
MBSFN configuration module 2206 may be configured to obtain an MCCH
from the first base station based on the received SIB 13 and obtain
an MBSFN configuration based on the obtained MCCH and the SIB 13.
The transmission module 2210 may be configured to transmit at least
one of a SIB 13, an MCCH change notification, or an MCCH, in which
the MCCH is transmitted synchronously with the first base station
at the frequency of the first base station.
[0166] The apparatus may include additional modules that perform
each of the blocks of the algorithm in the aforementioned flow
charts of FIGS. 15 and 17. As such, each block in the
aforementioned flow charts of FIGS. 15 and 17 may be performed by a
module and the apparatus may include one or more of those modules.
The modules may be one or more hardware components specifically
configured to carry out the stated processes/algorithm, implemented
by a processor configured to perform the stated
processes/algorithm, stored within a computer-readable medium for
implementation by a processor, or some combination thereof.
[0167] FIG. 23 is a diagram 2300 illustrating an example of a
hardware implementation for an apparatus 2202' employing a
processing system 2314. The processing system 2314 may be
implemented with a bus architecture, represented generally by the
bus 2324. The bus 2324 may include any number of interconnecting
buses and bridges depending on the specific application of the
processing system 2314 and the overall design constraints. The bus
2324 links together various circuits including one or more
processors and/or hardware modules, represented by the processor
2304, the reception module 2204, the MBSFN configuration module
2206, the MBMS session control module 2208, the transmission module
2210, and the computer-readable medium/memory 2306. The bus 2324
may also link various other circuits such as timing sources,
peripherals, voltage regulators, and power management circuits,
which are well known in the art, and therefore, will not be
described any further.
[0168] The processing system 2314 may be coupled to a transceiver
2310. The transceiver 2310 is coupled to one or more antennas 2320.
The transceiver 2310 provides a means for communicating with
various other apparatus over a transmission medium. The transceiver
2310 receives a signal from the one or more antennas 2320, extracts
information from the received signal, and provides the extracted
information to the processing system 2314, specifically the
reception module 2204. In addition, the transceiver 2310 receives
information from the processing system 2314, specifically the
transmission module 2210, and based on the received information,
generates a signal to be applied to the one or more antennas 2320.
The processing system 2314 includes a processor 2304 coupled to a
computer-readable medium/memory 2306. The processor 2304 is
responsible for general processing, including the execution of
software stored on the computer-readable medium/memory 2306. The
software, when executed by the processor 2304, causes the
processing system 2314 to perform the various functions described
supra for any particular apparatus. The computer-readable
medium/memory 2306 may also be used for storing data that is
manipulated by the processor 2304 when executing software. The
processing system further includes at least one of the modules
2204, 2206, 2208, and 2210. The modules may be software modules
running in the processor 2304, resident/stored in the computer
readable medium/memory 2306, one or more hardware modules coupled
to the processor 2304, or some combination thereof. The processing
system 2314 may be a component of the eNB 610 and may include the
memory 676 and/or at least one of the TX processor 616, the RX
processor 670, and the controller/processor 675.
[0169] In one configuration, the apparatus 2202/2202' for wireless
communication includes means for determining MBSFN subframes at a
frequency of a first base station. The first base station has a
first power class, and the apparatus 2202/2202' has a second power
class lower than the first power class. The apparatus includes
means for determining, in the MBSFN subframes, a first set of
symbols used for control information by the first base station and
a second set of symbols used for MBSFN signals by the first base
station. The apparatus includes means for transmitting, at the
frequency, unicast control information in a subset of the first set
of symbols. The apparatus includes means for transmitting, at the
frequency, unicast data with a reduced power in the second set of
symbols. The apparatus may include means for transmitting, at the
frequency, a SIB 13 in non-MBSFN subframes and an MCCH change
notification in the first set of symbols with a SIB 13 and an MCCH
change notification transmitted by the first base station. The
apparatus may include means for determining resources within the
second set of symbols used by the first base station for
transmitting an MCCH. The apparatus may include means for
transmitting, synchronously with the first base station at the
frequency, the MCCH in the second set of symbols within the
determined resources. The apparatus may include means for
determining additional resources within the second set of symbols
used by the first base station for transmitting an MTCH. The
apparatus may include means for transmitting, synchronously with
the first base station at the frequency, the MTCH in the second set
of symbols within the determined additional resources.
[0170] In one configuration, the apparatus may include means for
joining an MBMS session associated with a BM-SC. In this
configuration, the apparatus may have an M1 interface with an MBMS
gateway and an M2 interface with an MCE.
[0171] In another configuration, the apparatus may include means
for receiving USD bootstrapping information, means for obtaining a
USD based on the USD bootstrapping information, and means for
obtaining a multicast IP address and a source IP address from the
USD. The transmitted SIB 13, MCCH change notification, MCCH, and
MTCH may be based on the obtained multicast IP address and the
obtained source IP address. In this configuration, the apparatus
may have an M1 interface with an MBMS gateway.
[0172] In another configuration, the apparatus may include means
for sending an MBMS session start initiation to a BM-SC through the
MCE, the MME, and the MBMS gateway, and means for initiating an
MBMS session with the BM-SC. In this configuration, the apparatus
may have an M1 interface with an MBMS gateway and an M2 interface
with an MCE.
[0173] In another configuration, the apparatus may include means
for receiving information from an HMS, in which the MBSFN subframes
of the first base station are determined based on the information
received from the HMS. In one aspect, the information from the HMS
indicates an MBSFN configuration. In this aspect, the apparatus may
include means for transmitting, based on the MBSFN configuration,
at least one of a SIB 13, an MCCH change notification, an MCCH
synchronously with the first base station at the frequency, or an
MTCH synchronously with the first base station at the
frequency.
[0174] In another configuration, the apparatus may include means
for receiving a SIB 2 from the first base station, in which the
MBSFN subframes are determined based on the received SIB 2. The
apparatus may include means for receiving MSI, in which the MBSFN
subframes are further determined based on the received MSI.
[0175] In another configuration, the apparatus may include means
for receiving a SIB 13 from the first base station, means for
obtaining an MBSFN configuration based on the received SIB 13, and
means for transmitting a SIB 13 and an MCCH change notification
based on the MBSFN configuration.
[0176] In another configuration, the apparatus may include means
for receiving a SIB 13 from the first base station, means for
obtaining an MCCH from the first base station based on the received
SIB 13, means for obtaining an MBSFN configuration based on the
obtained MCCH and the SIB 13, and means for transmitting at least
one of a SIB 13, an MCCH change notification, an MCCH based on the
MBSFN configuration, and the MCCH may be transmitted synchronously
with the first base station at the frequency.
[0177] The aforementioned means may be one or more of the
aforementioned modules of the apparatus 2202 and/or the processing
system 2314 of the apparatus 2202' configured to perform the
functions recited by the aforementioned means. As described supra,
the processing system 2314 may include the TX Processor 616, the RX
Processor 670, and the controller/processor 675. As such, in one
configuration, the aforementioned means may be the TX Processor
616, the RX Processor 670, and the controller/processor 675
configured to perform the functions recited by the aforementioned
means.
[0178] It is understood that the specific order or hierarchy of
blocks in the processes/flow charts disclosed is an illustration of
exemplary approaches. Based upon design preferences, it is
understood that the specific order or hierarchy of blocks in the
processes/flow charts may be rearranged. Further, some blocks may
be combined or omitted. The accompanying method claims present
elements of the various blocks in a sample order, and are not meant
to be limited to the specific order or hierarchy presented.
[0179] The previous description is provided to enable any person
skilled in the art to practice the various aspects described
herein. Various modifications to these aspects will be readily
apparent to those skilled in the art, and the generic principles
defined herein may be applied to other aspects. Thus, the claims
are not intended to be limited to the aspects shown herein, but is
to be accorded the full scope consistent with the language claims,
wherein reference to an element in the singular is not intended to
mean "one and only one" unless specifically so stated, but rather
"one or more." The word "exemplary" is used herein to mean "serving
as an example, instance, or illustration." Any aspect described
herein as "exemplary" is not necessarily to be construed as
preferred or advantageous over other aspects. Unless specifically
stated otherwise, the term "some" refers to one or more.
Combinations such as "at least one of A, B, or C," "at least one of
A, B, and C," and "A, B, C, or any combination thereof" include any
combination of A, B, and/or C, and may include multiples of A,
multiples of B, or multiples of C. Specifically, combinations such
as "at least one of A, B, or C," "at least one of A, B, and C," and
"A, B, C, or any combination thereof" may be A only, B only, C
only, A and B, A and C, B and C, or A and B and C, where any such
combinations may contain one or more member or members of A, B, or
C. All structural and functional equivalents to the elements of the
various aspects described throughout this disclosure that are known
or later come to be known to those of ordinary skill in the art are
expressly incorporated herein by reference and are intended to be
encompassed by the claims. Moreover, nothing disclosed herein is
intended to be dedicated to the public regardless of whether such
disclosure is explicitly recited in the claims. No claim element is
to be construed as a means plus function unless the element is
expressly recited using the phrase "means for."
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