U.S. patent application number 14/232730 was filed with the patent office on 2014-06-12 for method for reporting system information in wireless communication and apparatus for supporting same.
This patent application is currently assigned to LG ELECTRONICS INC.. The applicant listed for this patent is Sung Duck Chun, Sung Hoon Jung, Young Dae Lee, Sung Jun Park, Seung June Yi. Invention is credited to Sung Duck Chun, Sung Hoon Jung, Young Dae Lee, Sung Jun Park, Seung June Yi.
Application Number | 20140162658 14/232730 |
Document ID | / |
Family ID | 47506738 |
Filed Date | 2014-06-12 |
United States Patent
Application |
20140162658 |
Kind Code |
A1 |
Jung; Sung Hoon ; et
al. |
June 12, 2014 |
METHOD FOR REPORTING SYSTEM INFORMATION IN WIRELESS COMMUNICATION
AND APPARATUS FOR SUPPORTING SAME
Abstract
A method for a terminal reporting system information in a
wireless communication system is disclosed. The method comprises:
receiving a system information report request of a neighboring cell
from a serving cell; deciding whether to report the system
information on the neighboring cell, which is obtained in advance,
to the serving cell; and reporting the system information that is
obtained in advance to the serving cell when a decision is made to
report the system information, wherein the system information that
is obtained in advance is system information of the neighboring
cell that is obtained before receiving the system information
report request.
Inventors: |
Jung; Sung Hoon; (Anyang-si,
KR) ; Lee; Young Dae; (Anyang-si, KR) ; Chun;
Sung Duck; (Anyang-si, KR) ; Park; Sung Jun;
(Anyang-si, KR) ; Yi; Seung June; (Anyang-si,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Jung; Sung Hoon
Lee; Young Dae
Chun; Sung Duck
Park; Sung Jun
Yi; Seung June |
Anyang-si
Anyang-si
Anyang-si
Anyang-si
Anyang-si |
|
KR
KR
KR
KR
KR |
|
|
Assignee: |
LG ELECTRONICS INC.
Seoul
KR
|
Family ID: |
47506738 |
Appl. No.: |
14/232730 |
Filed: |
July 13, 2012 |
PCT Filed: |
July 13, 2012 |
PCT NO: |
PCT/KR2012/005581 |
371 Date: |
January 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61507606 |
Jul 14, 2011 |
|
|
|
Current U.S.
Class: |
455/437 ;
455/550.1 |
Current CPC
Class: |
H04W 36/0094 20130101;
H04W 84/045 20130101; H04W 36/0007 20180801; H04W 36/0016 20130101;
H04W 36/0061 20130101; H04W 24/10 20130101 |
Class at
Publication: |
455/437 ;
455/550.1 |
International
Class: |
H04W 36/00 20060101
H04W036/00 |
Claims
1. A method for reporting system information by a UE in a wireless
communication system, the method comprising: receiving a system
information reporting request of a neighboring cell from a serving
cell; determining whether to report to the serving cell system
information of the neighboring cell acquired in advance; and
reporting to the serving cell the system information of the
neighboring acquired in advance when it is determined to report;
wherein the system information of the neighboring cell acquired in
advance is system information of the neighboring cell which is
acquired before receiving the system information reporting
request.
2. The method of claim 1, wherein the step of determining whether
to report the system information of the neighboring cell acquired
in advance includes, determining to report to the serving cell the
system information of the neighboring cell acquired in advance,
when the UE has the system information of the neighboring cell
acquired in advance.
3. The method of claim 2, further comprising: transmitting to the
serving cell control information regarding the system information
of the neighboring cell acquired in advance together with the
system information of the neighboring cell acquired in advance.
4. The method of claim 3, wherein the control information includes
an indicator indicating that the system information of the
neighboring cell acquired in advance is the system information of
the neighboring cell acquired before receiving a system information
reporting request message.
5. The method of claim 4, wherein the control information further
includes an indicator indicating the time when the system
information of the neighboring cell acquired in advance is
acquired.
6. The method of claim 1, further comprising: receiving from the
serving cell a ready-acquired system information report indicator
indicating whether reporting the system information of the
neighboring cell acquired in advance is allowed.
7. The method of claim 6, wherein the step of determining whether
to report to the serving cell the system information of the
neighboring cell acquired in advance includes, determining to
report to the serving cell the system information of the
neighboring cell acquired in advance, if the ready-acquired system
information report indicator indicates that the reporting the
system information is allowed and the UE has the system information
of the neighboring cell acquired in advance.
8. The method of claim 7, further comprising: transmitting to the
serving cell control information regarding the system information
of the neighboring cell acquired in advance together with the
system information of the neighboring cell acquired in advance.
9. The method of claim 8, wherein the control information further
includes an indicator indicating the time when the system
information of the neighboring cell acquired in advance is
acquired.
10. The method of claim 1, further comprising: when it is
determined not to report the system information, acquiring the
system information from the neighboring cell; and transmitting the
acquired system information to the serving cell.
11. A UE that operates in a wireless communication system, the UE
comprising: a radio frequency (RF) unit transmitting or receiving a
radio signal; and a processor operably coupled to the RF unit,
wherein the processor is configured for: receiving a system
information reporting request of a neighboring cell from a serving
cell, determining whether to report to the serving cell system
information of the neighboring cell acquired in advance, and
reporting to the serving cell the system information of the
neighboring acquired in advance when it is determined to report,
wherein the system information of the neighboring cell acquired in
advance is system information of the neighboring cell which is
acquired before receiving the system information reporting
request.
12. The UE of claim 11, wherein the determining whether to report
the system information of the neighboring cell acquired in advance
includes, determining to report to the serving cell the system
information of the neighboring cell acquired in advance, when the
UE has the system information of the neighboring cell acquired in
advance.
13. The UE of claim 12, wherein the processor is further configured
for, transmitting to the serving cell control information regarding
the system information of the neighboring cell acquired in advance
together with the system information of the neighboring cell
acquired in advance.
14. The UE of claim 13, wherein the control information includes an
indicator indicating that the system information of the neighboring
cell acquired in advance is the system information of the
neighboring cell acquired before receiving a system information
reporting request message.
15. The UE of claim 14, wherein the control information further
includes an indicator indicating the time when the system
information of the neighboring cell acquired in advance is
acquired.
16. The UE of claim 11, wherein the processor is further configured
for: receiving from the serving cell a ready-acquired system
information report indicator indicating whether reporting the
system information of the neighboring cell acquired in advance is
allowed.
17. The UE of claim 16, wherein the determining whether to report
to the serving cell the system information of the neighboring cell
acquired in advance includes, determining to report to the serving
cell the system information of the neighboring cell acquired in
advance, if the ready-acquired system information report indicator
indicates that the reporting the system information is allowed and
the UE has the system information of the neighboring cell acquired
in advance.
18. The UE of claim 17, wherein the processor is further configured
for, transmitting to the serving cell control information regarding
the system information of the neighboring cell acquired in advance
together with the system information of the neighboring cell
acquired in advance.
19. The UE of claim 18, wherein the control information further
includes an indicator indicating the time when the system
information of the neighboring cell acquired in advance is
acquired.
20. The UE of claim 11, wherein the processor is further configured
for: when it is determined not to report the system information,
acquiring the system information from the neighboring cell; and
transmitting the acquired system information to the serving cell.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a wireless communication
system, and more particularly, to a method for reporting system
information by a user equipment (UE) in a wireless communication
system and an apparatus for supporting the same.
[0003] 2. Related Art
[0004] 3.sup.rd generation partnership project (3GPP) long term
evolution (LTE) which is improvement of a universal mobile
telecommunications system (UMTS) is introduced as 3GPP release 8.
The 3GPP LTE uses orthogonal frequency division multiple access
(OFDMA) in a downlink and uses single carrier-frequency division
multiple access (SC-FDMA) in an uplink. Multiple input multiple
output (MIMO) having maximum four antennas are adopted. In recent
years, 3GPP LTE-advanced (LTE-A) which is an evolution of the 3GPP
LTE has been discussed.
[0005] A closed subscriber group (CSG) allows a limited access for
only a specific subscriber to be introduced to provide a service
having higher quality. A base station that can provide a CSG
service may be home eNodeB (HNB) and a cell providing an authorized
service to CSG subscribers may be a CSG cell. In the 3GPP, a basic
requirement of the CSG is disclosed in 3GPP TS 22.220 V1.0.1
(2008-12) "Service requirements for Home NodeBs and Home eNodeBs
(Release 9)".
[0006] A feature of a CSG cell limitatively providing the service
is illustrated even in handover to the CSG cell. Whether a user
equipment (UE) is a CSG member of a corresponding cell may be
problematic in performing the handover to the CSG cell. As a
result, the handover to the CSG cell may be implemented by a first
step in which the UE reports a cell measurement result and a second
step in which the UE acquires system information from a target cell
and reports the acquired system information to a service cell.
[0007] When a UE receives a message indicating that system
information of a neighboring cell will be reported from a serving
cell, the UE acquires the system information by accessing the
neighboring cell. The acquired system information is transmitted to
the serving cell. While the UE accesses the neighboring cell in
order to acquire the system information, the serving cell cannot
transmit any command/message/data to the UE.
[0008] Meanwhile, the UE may acquire system information regarding
the neighboring cell in advance before being instructed with
reporting the system information from the serving cell. Even in
such a case, the UE may perform accessing the neighboring cell by
leaving the serving cell in order to newly acquire the system
information regarding the neighboring cell as an unnecessary step
in some cases. Therefore, a more efficient system information
reporting method of the UE is required.
SUMMARY OF THE INVENTION
[0009] An object of the present invention is to provide a method
for reporting performed by a in a wireless communication system and
an apparatus for supporting the same.
[0010] In an aspect, a method for reporting system information by a
UE in a wireless communication system is provided. The method
includes receiving a system information reporting request of a
neighboring cell from a serving cell, determining whether to report
to the serving cell system information of the neighboring cell
acquired in advance, and reporting to the serving cell the system
information of the neighboring acquired in advance when it is
determined to report. The system information of the neighboring
cell acquired in advance is system information of the neighboring
cell which is acquired before receiving the system information
reporting request.
[0011] The step of determining whether to report the system
information of the neighboring cell acquired in advance may include
determining to report to the serving cell the system information of
the neighboring cell acquired in advance, when the UE has the
system information of the neighboring cell acquired in advance.
[0012] The method may further include transmitting to the serving
cell control information regarding the system information of the
neighboring cell acquired in advance together with the system
information of the neighboring cell acquired in advance.
[0013] The control information may include an indicator indicating
that the system information of the neighboring cell acquired in
advance is the system information of the neighboring cell acquired
before receiving a system information reporting request
message.
[0014] The control information may further include an indicator
indicating the time when the system information of the neighboring
cell acquired in advance is acquired.
[0015] The method may further include receiving from the serving
cell a ready-acquired system information report indicator
indicating whether reporting the system information of the
neighboring cell acquired in advance is allowed.
[0016] The step of determining whether to report to the serving
cell the system information of the neighboring cell acquired in
advance may include determining to report to the serving cell the
system information of the neighboring cell acquired in advance, if
the ready-acquired system information report indicator indicates
that the reporting the system information is allowed and the UE has
the system information of the neighboring cell acquired in
advance.
[0017] The method may further include transmitting to the serving
cell control information regarding the system information of the
neighboring cell acquired in advance together with the system
information of the neighboring cell acquired in advance.
[0018] The control information may further include an indicator
indicating the time when the system information of the neighboring
cell acquired in advance is acquired.
[0019] The method may further include, when it is determined not to
report the system information, acquiring the system information
from the neighboring cell and transmitting the acquired system
information to the serving cell.
[0020] In another aspect, a UE that operates in a wireless
communication system is provided. The UE include a radio frequency
(RF) unit transmitting or receiving a radio signal and a processor
operably coupled to the RF unit. The processor is configured for
receiving a system information reporting request of a neighboring
cell from a serving cell, determining whether to report to the
serving cell system information of the neighboring cell acquired in
advance, and reporting to the serving cell the system information
of the neighboring acquired in advance when it is determined to
report. The system information of the neighboring cell acquired in
advance is system information of the neighboring cell which is
acquired before receiving the system information reporting
request.
[0021] Through a method for reporting system information according
to an embodiment of the present invention, a time used for a UE to
report system information of a neighboring cell to a serving cell
can be decreased. Therefore, a handover delay of a handover
procedure requiring system information of a target cell can be
decreased. Further, a procedure in which the UE unnecessarily
receives the system information of the neighboring cell is skipped,
and as a result, a time when the serving cell loses controllability
of the UE can be decreased. Therefore, mobility increased by the UE
can be more efficiently supported and efficiency of traffic
processing between the UE and a cell can be increased, thereby
improving processing rate of an entire system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 illustrates a wireless communication system according
to the present invention.
[0023] FIG. 2 is a block diagram illustrating a radio protocol
architecture for a user plane.
[0024] FIG. 3 is a block diagram illustrating a radio protocol
architecture for a control plane.
[0025] FIG. 4 is a flowchart illustrating an operation of a UE in
an RRC idle state.
[0026] FIG. 5 is a flowchart illustrating a process of establishing
an RRC connection.
[0027] FIG. 6 is a flowchart illustrating a process of
reconfiguring the RRC connection.
[0028] FIG. 7 is an exemplary diagram illustrating a radio link
failure.
[0029] FIG. 8 is a flowchart illustrating a success in a process of
reestablishing a connection.
[0030] FIG. 9 is a flowchart illustrating a failure in the process
of reestablishing the connection.
[0031] FIG. 10 is a flowchart illustrating the existing measurement
performing method.
[0032] FIG. 11 illustrates one example of a measurement
configuration configured for the UE.
[0033] FIG. 12 illustrates an example of deleting a measurement
identity.
[0034] FIG. 13 illustrates an example of deleting a measurement
object.
[0035] FIG. 14 is a diagram illustrating one example of a wireless
communication system illustrating a HeNB operation.
[0036] FIG. 15 exemplifies a CSG scenario.
[0037] FIG. 16 exemplifies a pico scenario.
[0038] FIG. 17 is a flowchart illustrating an operation of a UE
that performs the method for reporting system information according
to an embodiment of the present invention.
[0039] FIG. 18 is a flowchart illustrating one example of a method
for reporting system information according to an embodiment of the
present invention.
[0040] FIG. 19 illustrates an operating flowchart of a UE that
performs the method for reporting system information according to
an embodiment of the present invention.
[0041] FIG. 20 is a flowchart illustrating one example of a method
for reporting system information according to an embodiment of the
present invention.
[0042] FIG. 21 is a diagram illustrating another example of the
method for reporting system information according to an embodiment
of the present invention.
[0043] FIG. 22 is a block diagram illustrating a wireless apparatus
which may be implemented by the embodiment of the present
invention.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0044] FIG. 1 illustrates a wireless communication system according
to the present invention. The wireless communication system may
also be called an evolved-UMTS terrestrial radio access network
(E-UTRAN) or a long term evolution (LTE)/LTE-A system.
[0045] The E-UTRAN includes a base station (BS) 20 that provides a
control plane and a user plane to a user equipment (UE) 10. The UE
10 may be fixed or movable and may be called other terms such as a
mobile station (MS), a user terminal (UT), a subscriber station
(SS), a mobile terminal (MT), a wireless device, and the like. The
base station 20 represents a fixed station that communicates with
the UE 10, and may be called other terms such as an evolved-NodeB
(eNB), a base transceiver system (BTS), an access point, and the
like.
[0046] The base stations 20 may be connected to each other through
an X2 interface. The base station 20 is connected with an evolved
packet core (EPC) 30 through an S1 interface, in more detail, a
mobility management entity (MME) through an S1 MME and a serving
gateway (S-GW) through an SI-U.
[0047] The EPC 30 is constituted the MME, the S-GW, and a packet
data network gateway (P-GW). The MME has access information of the
UE or information on a capability of the UE, and the information is
primarily used for mobility management of the UE. The S-GW is a
gateway having the E-UTRAN as an end point and the P-GW is a
gateway having a PDN as the end point.
[0048] Layers of a radio interface protocol between the UE and a
network may be divided into an L1 (first layer), an L2 (second
layer), and an L3 (third layer) based three lower layers of an open
system interconnection (OSI) reference model which is widely known
in a communication system and among them, a physical layer that
belongs to the first layer provides an information transfer service
using a physical channel and a radio resource control (RRC) layer
positioned on the third layer serves to control radio resources
between the UE and the network. To this end, the RRC layer
exchanges an RRC message between the UE and the base station.
[0049] FIG. 2 is a block diagram illustrating a radio protocol
architecture for a user plane. FIG. 3 is a block diagram
illustrating a radio protocol architecture for a control plane. A
data plane is a protocol stack for user data transmission and the
control plane is a protocol stack for transmitting a control
signal.
[0050] Referring to FIGS. 2 and 3, a physical (PHY) layer provides
the information transfer service to an upper layer by using the
physical channel. The physical layer is connected with a medium
access control (MAC) layer as an upper layer through a transport
channel. Data move between the MAC layer and the physical layer
through the transport channel. The transport channel is classified
depending on a transmission method and a transmission feature
through a radio interface.
[0051] Data move between different physical layers, that is,
between physical layers of a transmitter and a receiver through the
physical channel. The physical channel may be modulated by
orthogonal frequency division multiplexing (OFDM) and uses a time
and a frequency as the radio resource.
[0052] A function of the MAC layer includes mapping between a logic
channel and the transport channel, and multiplexing/demultiplexing
to a transport block provided to the physical channel onto the
transport channel of an MAC service data unit (SDU) that belongs to
the logic channel. The MAC layer provides a service to a radio link
control (RLC) layer through the logic channel.
[0053] A function of the RLC layer includes concatenation,
segmentation, and reassembly of an RLC SDU. In order to assure
various quality of services (QoS) requested by a radio bearer (RB),
the RLC layer provides three operating modes of a transparent mode
(TM), an unacknowledged mode (UM), and an acknowledged mode (AM).
An AM RLC provides error correction through an automatic repeat
request (ARQ).
[0054] A function of a packet data convergence protocol (PDCP)
layer on the user plane includes transferring of user data, header
compression, and ciphering. A function of a packet data convergence
protocol (PDCP) layer on the user plane includes transferring of
control plane data and ciphering/integrity protection.
[0055] The radio resource control (RRC) layer is defined only on
the control plane. The RRC layer serves to control the logic
channel, the transport channel and the physical channels in
association with configuration, re-configuration, and release of
radio bearers. The RB means a logic route provided by the first
layer (PHY layer) and the second layers (the MAC layer, the RLC
layer, and the PDCP layer) in order to transfer data between the UE
and the network.
[0056] Setting the RB defines features of the radio protocol layer
and channel in order to provide a specific service and means a
process of setting respective detailed parameters and operating
methods. The RB may be re-divided into two types of a signaling RB
(SRB) and a data RB (DRB). The SRB is used as a passage for
transmitting the RRC message on the control plane and the DRB is
used as a passage for transmitting the user data on the user
plane.
[0057] When an RRC connection is established between the RRC layer
of the UE and the RRC layer of the E-UTRAN, the UE is in an RRC
connected state and if not, the UE is in an RRC idle state.
[0058] A downlink transport channel for transmitting data from the
network to the UE includes a broadcast channel (BCH) for
transmitting system information and besides, the downlink transport
channel includes a downlink shared channel (SCH) for transmitting
user traffic or a control message. Traffic or a control message of
a downlink multicast or broadcast service may be transported
through the downlink SCH or transported through an additional
downlink multicast channel (MCH). Meanwhile, an uplink transport
channel for transporting data from the UE to the network includes a
random access channel (RACH) for transporting an initial control
message and besides, an uplink shared channel (SCH) for
transporting the user traffic or control message.
[0059] The logical channel that is positioned on the transport
channel and mapped to the transport channel includes a broadcast
control channel (BCCH), a paging control channel (PCCH), a common
control channel (CCCH), a multicast control channel (MCCH), a
multicast traffic channel (MTCH), and the like.
[0060] The physical channel is constituted by a plurality of OFDM
symbols in a time domain and a plurality of sub-carriers in a
frequency domain. One sub-frame is constituted by the plurality of
OFDM symbols in the time domain. A resource block as a resource
allocation unit is constituted by the plurality of OFDM symbols and
the plurality of sub-carriers. Further, each sub-frame may use
specific sub-carriers of specific OFDM symbols (e.g., a first OFDM
symbol) of a corresponding sub-frame for the physical downlink
control channel (PDCCH), that is, an L1/L2 control channel. A
transmission time interval (TTI) is a unit time of transmitting the
sub-frame.
[0061] Hereinafter, the RRC state and the RRC connection method of
the UE will be described in detail.
[0062] The RRC state represents whether the RRC layer of the UE is
logically connected with the RRC layer of the E-UTRAN and a case in
which both RRC layers are logically connected to each other is
called the RRC connection state and a case in which both RRC layers
are not logically connected to each other is called the RRC idle
state. Since the RRC connection exists in the UE in the RRC
connection state, the E-UTRAN may determine the existence of the
corresponding UE by the unit of a cell to thereby effectively
control the UE. On the contrary, the E-UTRAN may not determine the
UE in the RRC idle state and a core network (CN) is managed by the
unit of a tracking area which a region unit larger than the cell.
That is, it is determined whether the UE in the RRC idle state
exists by the unit of a large region, and the UE needs to move to
the RRC connection state in order to receive a general mobile
communication service such as voice or data.
[0063] When a user first turns on a power supply of the UE, the UE
first retrieves an appropriate and thereafter, the UE stays in the
RRC idle state in the corresponding cell. The UE in the RRC idle
state establishes the RRC connection with the E-UTRAN through an
RRC connection procedure at least when the UE in the RRC idle state
needs to make the RRC connection, and is transited to the RRC
connections state. Cases in which the UE in the RRC idle state
needs to make the RRC connection are various, and for example,
uplink data transmission is required due to a user's call attempt
or when a paging message is received from the E-UTRAN, the cases
may include response message transmission thereto.
[0064] A non-access stratum layer located above the RRC layer
performs functions such as session management and mobility
management.
[0065] In order to manage mobility of the UE on the NAS layer, two
states of EPS mobility management (EMM)-REGISTERED and
EMM-DEREGISTERED are defined and both states are applied to the UE
and the MME. An initial UE is in the EMM-DEREGISTERED state and the
UE performs a process of registering the initial UE in a
corresponding network through an initial attach procedure in order
to access the network. When the attach procedure is successfully
performed, the UE and the MME are in the EMM-REGISTERED state.
[0066] In order to manage a signaling connection between the UE and
the EPC, two states of an EPS connection management (ECM)-IDLE
state and an ECM-CONNECTED state are defined and both states are
applied to the UE and the MME. When the UE in the ECM-IDLE state
makes the RRC connection with the E-UTRAN, the corresponding UE is
in the ECM-CONNECTED state. When the MME in the ECM-IDLE state
makes an S1 connection with the E-UTRAN, the MME is in the
ECM-CONNECTED state. When the UE is in the ECM-IDLE state, the
E-UTRAN does not have context information of the UE. Therefore, the
UE in the ECM-IDLE state performs a UE based mobility associated
procedure such as cell selection or cell reselection without the
need for receiving a command of the network. On the contrary, when
the UE is in the ECM-CONNECTED state, the mobility of the UE is
managed by the command of the network. When the position of the UE
in the ECM-IDLE state is different from a position which the
network knows, the UE notifies a corresponding position of the UE
to the network through a tracking area update procedure.
[0067] Next, the system information will be described.
[0068] The system information includes required information which
the UE needs to know to access the base station. Therefore, the UE
needs to receive all of the system information before accessing the
base station and further, the UE continuously needs to have latest
system information. In addition, since the system information is
information which all UEs in one cell need to know, the base
station periodically transmits the system information.
[0069] According to Phrase 5.2.2 of 3GPP TS 36.331 V8.7.0 (2009-09)
"Radio Resource Control (RRC); Protocol specification (Release 8)",
the system information is divided in to a master information block
(MIB), a scheduling block (SB), and a system information block
(SIB). The MIB allows the UE to know a physical component, for
example, a bandwidth. The SB allows the UE to know transmission
information of the SIBs, for example, a transmission period, and
the like. The SIB is an aggregate of associated system information.
For example, any SIB includes only information on a neighboring
cell and any SIB includes only information on a uplink wireless
channel used by the UE.
[0070] In general, a service which the network provides to the UE
may be divided into three types. Further, the UE differently
recognizes even a type of the cell by considering which service the
UE receives. The service type will be first described below and
thereafter, the type of the cell will be described.
[0071] Limited service: The service may provide an emergency call
and an earthquake and Tsunami warning system (ETWS), and provide
the emergency call and the earthquake and Tsunami warning system
(ETWS) in an acceptable cell.
[0072] Normal service: The service may mean a public use general
service and may provide the public use general service in a
suitable or normal cell.
[0073] Operator service: The service may mean a service for a
communication network operator and only the communication network
operator may use the cell and a general user may not use the
cell.
[0074] The type of the cell may be divided as below in association
with the service type provided by the cell.
[0075] 1) Acceptable cell: Cell where the UE may receive the
limited service. The cell is a cell that is not barred in terms of
the corresponding UE and satisfies a cell selection criterion of
the UE.
[0076] 2) Suitable cell: Cell where the UE may receive the suitable
service. The cell satisfies a condition of the acceptable cell and
simultaneously, satisfies additional conditions. As the additional
conditions, the cell needs to belong to a public land mobile
network (PLMN) which the corresponding UE may access and needs to
be a cell where execution of the tracking area update procedure of
the UE is not barred. When the corresponding cell is the CSG cell,
the corresponding cell needs to be a cell where the UE may access
the cell as a CSG member.
[0077] 3) Barred cell: The cell is a cell where information
indicating that the corresponding cell is a cell barred through the
system information is broadcasted.
[0078] 4) Reserved cell: The cell is a cell where information
indicating that the corresponding cell is a cell reserved through
the system information is broadcasted.
[0079] FIG. 4 is a flowchart illustrating an operation of a UE in
an RRC idle state. FIG. 4 illustrates a procedure of registering a
UE of which initial power is turned on in the network through a
cell selection process and thereafter, cell reselection is
performed as necessary.
[0080] Referring to FIG. 4, the UE selects radio access technology
(RAT) for communicating with the public land mobile network from
which the UE itself intends to receive the service (S410).
Information on the PLMN and the RAT may be selected by a user of
the UE and the information stored in a universal subscriber
identity module (USIM) may be used.
[0081] The UE selects a cell having a largest value among cell
having measured larger signal intensity or quality than specific
values (cell selection) (S420). The UE of which power is turned on
performs the cell selection and the execution of the cell selection
may be called initial cell selection. A cell selection procedure
will be described below in detail. After the cell selection, the UE
receives the system information which the base station periodically
sends. The aforementioned specific value represents a value defined
in the system in order to receive an assurance for quality of a
physical signal in transmitting/receiving data. Therefore, the
value may vary depending on the applied RAT.
[0082] When network registration is required, the UE performs a
network registration procedure (S430). The UE registers its own
information (e.g., IMSI) in order to receive a service (e.g.,
paging)n from the network. The UE does not register the information
in the accessed network whenever selecting the cell, and registers
the information when information (e.g., a tracking area identity
(TAI) of the network that receives from the system information) is
different from information on a network known by the UE).
[0083] The UE performs the cell reselection based on a service
environment provided by the cell or an environment of the UE
(S440). When a value of measured intensity or quality of the signal
from a base station from which the UE receives the service is
smaller than a value measured from a base station of a neighboring
cell, the UE selects one of other cells that provide a more
excellent signal feature than the cell of the base station accessed
by the UE. This process is distinguished from the initial cell
selection as Process No. 2 to be cell re-selection. In this case, a
temporal constraint is given in order to prevent the cell from
being frequently reselected with the variation of the signal
feature. A cell selection procedure will be described below in
detail.
[0084] FIG. 5 is a flowchart illustrating a process of establishing
an RRC connection.
[0085] The UE sends to the network an RRC connection request
message for requesting the RRC connection (S510). The network sends
an RRC connection setup message as a response to the RRC connection
request (S520). The UE enters an RRC connection mode after
receiving the RRC connection setup message.
[0086] The UE sends to the network an RRC connection setup complete
message used to verify successful completion of establishing the
RRC connection (S530).
[0087] FIG. 6 is a flowchart illustrating a process of
reconfiguring the RRC connection. The RRC connection
reconfiguration is used to modify the RRC connection. The RRC
connection reconfiguration is used for perform RB
establishment/modification/release, handover, and measurement
setup/modification/release.
[0088] The network sends to the UE an RRC connection setup message
for modifying the RRC connection (S610). The UE sends to the
network an RRC connection reconfiguration complete message used to
verify successful completion of establishing the RRC connection
reconfiguration as a response to the RRC connection reconfiguration
(S620).
[0089] Hereinafter, a radio link failure will be described.
[0090] The UE performs continuously performs measurement for the
quality of a radio link with the serving cell that receives the
service. The UE decides whether communication is impossible under a
current situation due to deterioration in quality of the radio link
with the serving cell. When the communication is almost impossible
due to too low quality of the serving cell, the UE decides the
current situation as a wireless connection failure.
[0091] When a radio link failure is decided, the UE abandons
maintaining communication with a current serving cell, selects a
new cell through the cell selection (alternatively, cell
reselection) procedure, and attempts RRC connection
re-establishment to a new cell.
[0092] FIG. 7 is an exemplary diagram illustrating a radio link
failure. An operation associated with the radio link failure may be
described as two phases.
[0093] In a first phase, the UE is in a normal operation and checks
whether there is a problem in a current communication link. When
the problem is detected, the UE declares a radio link problem and
waits for recovery of the radio link for a first stand-by time T1.
When the radio link is recovered until the first stand-by time
elapses, the UE performs the normal operation again. When the radio
link is not recovered until the first stand-by time is expired, the
UE declares the radio link failure and the UE enters a second
phase.
[0094] In the second phase, the UE waits for recovering the radio
link for the second stand-by time T2. When the radio is not
recovered until the second stand-by time is expired, the UE enters
the RRC idle state. Alternatively, the UE may perform the RRC
re-establishment procedure.
[0095] The RRC connection re-establishment procedure is a procedure
of re-establishing the RRC connection again in the RRC_CONNECTED
state. Since the UE stays in the RRC_CONNECTED state, that is,
since the UE does not enter the RRC_IDLE state, the UE does not
initialize all of radio configurations (e.g., radio bearer
configurations) thereof. Instead, when the UE starts the RRC
connection reconfiguration procedure, the UE temporarily suspends
using all of the radio bearers except for SRB0. When the RRC
connection reconfiguration is succeeded, the UE resumes using the
radio bearers of which the use is temporarily suspended.
[0096] FIG. 8 is a flowchart illustrating a success in a process of
reestablishing a connection.
[0097] The UE selects a cell by performing the cell selection. The
UE receives the system information in order to receive basic
parameters for accessing the cell in the selected cell. In
addition, the UE sends to the base station the RRC connection
reestablishment request message (S810).
[0098] When the selected cell is a cell having a context of the UE,
that is, a prepared cell, the base station permits the RRC
connection reestablishment request of the UE and sends to the UE
the RRC connection reestablishment message (S820). The UE sends to
the base station the RRC connection reestablishment complete
message to succeed in the RRC connection re-establishment procedure
(S830).
[0099] FIG. 9 is a flowchart illustrating a failure in the process
of reestablishing the connection. The UE sends to the base station
the RRC connection reestablishment request message (S810). When the
selected cell is not the prepared cell, the base station sends an
RRC connection re-establishment reject message to the UE as a
response to the RRC connection reestablishment request (S815).
[0100] Next, a procedure in which the UE selects the cell will be
described in detail.
[0101] When the power of the UE is turned on or the UE stays in the
cell, the UE performs procedures for receiving the service by
selecting/reselecting a cell having appropriate quality.
[0102] The UE in the RRC idle state needs to prepare for receiving
the service through the cell by continuously selecting the cell
having the appropriate quality. For example, the UE of which the
power is just turned on needs to select the cell having the
appropriate quality for registration in the network. When the UE in
the RRC connection state enters the RRC idle state, the UE needs to
select a cell to stay in the RRC idle state. As such, a process in
which the UE selects a cell that satisfies a predetermined
condition in order to stay in a service stand-by state such as the
RRC idle state is referred to as the cell selection. Since the UE
performs the cell selection while the cell in the RRC idle state
may not be decided at present, it is important to select the cell
rapidly as possible. Therefore, in the case of a cell that provides
radio signal quality having a predetermined reference or more, even
though the cell is not a cell that provides the best radio signal
quality for the UE, the cell may be selected in the cell selection
process by the UE.
[0103] Hereinafter, a method and a procedure for selecting the cell
by the UE in the 3GPP LTE will be described in detail with
reference to 3GPP TS 36.304 V8.5.0 (2009-03) "User Equipment (UE)
procedures in idle mode (Release 8)".
[0104] When the power of the UE is turned on at an initial stage,
the UE retrieves the public land mobile network (PLMN) and selects
an appropriate PLMN capable of receiving the service. The PLMN is a
network that is deployed or operated by a mobile network operator.
Each mobile network operator operates one or more PLMNs. The
respective PLMNs may be identified by a mobile country code (MCC)
and a mobile network code (MNC). PLMN information of the cell is
included in the system information and broadcasted. The UE attempts
to register the selected PLMN. When the registration is succeeded,
the selected PLMN becomes a registered PLMN (RPLMN). The network
may signal a PLMN list to the UE and the PLMNs included in the PLMN
list may be considered as the PLMN such as the RPLMN. The UE
registered in the network needs to be reachable by the network.
When the UE is in the ECM-CONNECTED state (similarly, the RRC
connection state), the network recognizes that the UE receives the
service). However, when the UE is in the ECM-IDLE state (similarly,
the RRC idle state), a situation of the UE is not effective in the
eNB, but the situation is stored in the MME. In this case, the
position of the UE which is in the ECM-IDLE state is known to only
the MME as granularity of a list of tracking areas (TAs). A single
TA is identified by a tracking area identity configured by the PLMN
identity to which the TA belongs and the tracking area code (TAC)
uniquely expressing the TA in the PLMN.
[0105] Subsequently, the UE selects a cell having signal quality
and feature to receive an appropriate service among cells provided
by the selected PLMN.
[0106] The cell selection process is generally divided into two
types.
[0107] First, as an initial cell selection process, the UE has no
advance information on the radio channel during this process.
Therefore, the UE retrieves all radio channels in order to find the
appropriate cell. The UE finds the strongest cell in each channel.
Thereafter, the UE selects the corresponding cell only at the time
of finding the suitable cell that satisfies the cell selection
criterion.
[0108] Next, the UE may select the cell by using stored information
or using information broadcasted in the cell. Therefore, the cell
selection may be rapidly performed as compared with the initial
cell selection process. When the UE only finds the cell that
satisfies the cell selection criterion, the UE selects the
corresponding cell. When the UE does not find the suitable cell
that satisfies the cell selection criterion through such a process,
the UE performs the initial cell selection process.
[0109] After the UE selects a predetermined cell through the cell
selection process, the strength or quality of the signal between
the UE and the base station may be changed due to the mobility of
the UE or a change of a wireless environment. Therefore, when the
quality of the selected cell deteriorates, the UE may select
another that provides higher quality. When the cell is again
selected as such, a cell that provides higher signal quality than
the currently selected cell is generally selected. The process is
referred to as the cell reselection. The cell reselection process
generally has a basic object o select the cell having the highest
quality to the UE.
[0110] In addition to the quality of the radio signal, the network
decides a priority for each frequency to notify the priority to the
UE. The UE that receives the priority preferentially considers the
priority to a radio signal quality criterion during the cell
reselection process.
[0111] There may be a method for selecting or reselecting the cell
according to the signal feature of the wireless environment and
there may be a cell reselection method described below according to
the features of the RAT and the frequency of the cell. [0112]
Intra-frequency cell reselection: The UE reselect a cell having the
same RAT and the same center-frequency as a cell which is being
camping. [0113] Inter-frequency cell reselection: The UE reselects
a cell having the same RAT and a different center-frequency as the
cell which is being camping. [0114] Inter-RAT cell reselection: The
UE reselect a cell using an RAT different from an RAT which is
being camping.
[0115] A principle of the cell reselection process will be
described below.
[0116] First, the UE measures the qualities of the serving cell and
the neighboring cell for the cell reselection.
[0117] Second, the reselection is performed based on the cell
reselection criterion. The cell reselection criterion has features
described below in association with the measurement of the serving
cell and the neighboring cell.
[0118] The intra-frequency cell reselection is basically based on
ranking. The ranking defines an index value for evaluating the cell
reselection and the cells are ordered in the order of the index
value by using the index value. A cell having the best index is
generally called a best ranked cell. The cell index value is based
on a value which the UE measures for the corresponding cell and is
applied with a frequency offset or a cell offset as necessary.
[0119] The inter-frequency cell reselection is based on a frequency
priority provided by the network. The UE attempts to camp on a
frequency having the highest frequency priority. The network may
provide the frequency priority to which in-cell UEs will commonly
apply through broadcast signaling or provide a frequency-dedicated
priority for each UE through UE-dedicated signaling.
[0120] The network may provide a parameter (e.g., a
frequency-specific offset) used for the cell reselection to the UE
for the inter-frequency cell reselection for each frequency.
[0121] The network may provide a neighboring cell list (NCL) used
for the cell reselection to the UE for the intra-frequency cell
reselection or the inter-frequency cell reselection. The NCL
includes a cell-specific parameter (e.g., cell-specific offset)
used in the cell reselection.
[0122] The network may provide a cell reselection black list used
for the cell reselection to the UE for the intra-frequency cell
reselection or the inter-frequency cell reselection. The UE does
not perform the cell reselection for a cell included in the black
list.
[0123] Subsequently, the ranking performed during the cell
reselection evaluating process will be described.
[0124] A ranking criterion used to give the priority of the cell is
defined as illustrated in Equation 1.
R.sub.S=Q.sub.meas,s+Q.sub.hyst,R.sub.n=Q.sub.meas,n-Q.sub.offset
[Equation 1]
[0125] Herein, Rs represents a ranking criterion of the serving
cell, Rn represents a ranking criterion of the neighboring cell,
Qmeas,s represents a quality value which the UE measures for the
serving cell, Qmeas,n represents a quality value which the UE
measures for a neighboring cell, Qhyst represents a hysteresis
value for the ranking, and Qoffset represents an offset between two
cells.
[0126] In an intra-frequency, when the UE receives an offset
Qoffsets,n between the serving cell and the neighboring cell,
Qffoset=Qoffsets,n and when the UE does not receive Qoffsets,n,
Qoffset=0.
[0127] In an inter-frequency, when the UE receives the offset
Qoffsets,n fir the corresponding cell,
Qoffset=Qoffsets,n+Qfrequency and when the UE does not receive
Qoffsets,n, Qoffset=Qfrequency.
[0128] When the ranking varies while the ranking criterion Rs of
the serving cell and the ranking criterion of the neighboring cell
Rn are similar to each other, the ranking is frequently reversed,
and as a result, the UE may alternatively reselect both cells.
Qhyst represents a parameter for preventing the UE from
alternatively reselecting both cells by giving hysteresis in cell
reselection.
[0129] The UE measures the Rs of the serving cell and the Rn of the
neighboring cell according to the above equation and regards a cell
having the largest ranking criterion value as the best ranked cell
and reselects this cell.
[0130] According to the criterion, it can be seen that the quality
of the cell acts as the most important criterion in the cell
reselection. If the reselected cell is not the suitable cell, the
UE excludes the corresponding frequency or the corresponding cell
from a cell reselection target.
[0131] Hereinafter, a measurement and a measurement report will be
described.
[0132] Supporting the mobility of the UE is required in the mobile
communication system. Therefore, the UE continuously measures a
quality for a serving cell that provides the service at present and
a quality for a neighboring cell. The UE reports a measurement
result to the network at an appropriate time and the network
provides optimal mobility to the UE through handover. A measurement
for the object is often called a radio resource management (RPM)
measurement.
[0133] The UE may perform a measurement having a specific object
set by the network and report a result of the measurement to the
network in order to provide information that may help an operator
to operate the network in addition to the object of supporting the
mobility. For example, the UE receives broadcast information of a
specific cell decided by the network. The UE may report a cell
identity (also referred to as a global cell identity) of the
specific cell, identification information (for example, tracking
area code) to which the specific cell belongs, and/or other cell
information (for example, whether the specific cell is a member of
the closed subscriber group (CSG) cell) to the serving cell.
[0134] When the UE which is moving verifies that a quality of a
specific region is too bad through the measurement, positional
information on cells having a bad quality and a measurement result
may be reported to the network. The network may attempt
optimization of the network based on reporting of measurement
results of UEs that help operating the network.
[0135] In the mobile communication system in which a frequency
reuse factor is 1, mobility is generally made among different cells
in the same frequency band. Therefore, in order to well assure the
mobility of the UE, the UE may well measure the qualities and cell
information of the neighboring cells having the same
center-frequency as the serving cell. A measurement for a cell
having the same center-frequency as the serving cell as such is
called an intra-frequency measurement. The UE reports a measurement
result to the network at an appropriate time by performing the
intra-frequency measurement to achieve an object of the
corresponding measurement result.
[0136] The mobile communication operator may operate the network by
using a plurality of frequency bands. When the service of the
communication system is provided through the plurality of frequency
bands, the UE needs to be able to measure the qualities and cell
information of the neighboring cells having a different
center-frequency from the serving cell for assuring the optimized
mobility for the UE. A measurement for a cell having the different
center-frequency as the serving cell as such is called an
inter-frequency measurement. The UE needs to be able to report a
measurement result to the network at an appropriate time by
performing the inter-frequency measurement.
[0137] When the UE supports a measurement for heterogeneous
networks, the UE may perform a measurement for cells of the
heterogeneous networks by a base station configuration. The
measurement for the heterogeneous networks is called an inter-radio
access technology (RAT) measurement. For example, the RAT may
include a UMTS terrestrial radio access network (UTRAN) and a GSM
edge radio access network (GERAN) that follows a 3GPP standard
specification, and may include even a CDMA 2000 system that follows
a 3GPP2 standard specification.
[0138] FIG. 10 is a flowchart illustrating the existing measurement
performing method.
[0139] The UE receives measurement configuration information from
the base station (S1010). A message including the measurement
configuration information is referred to as a measurement
configuration message. The UE performs a measurement based on the
measurement configuration information (S1020). When a measurement
result satisfies a reporting condition in the measurement
configuration information, the UE reports the measurement result to
the base station (S1030). A message including the measurement
result is referred to as a measurement report message.
[0140] The measurement configuration information may include
information described below.
[0141] (1) Measurement object information: Represents information
on an object for which the UE will perform the measurement. A
measurement object includes at least one among an intra-frequency
measurement object which is an object of an intra-measurement, an
inter-frequency measurement object which is an object of an
inter-measurement, and an inter-RAT measurement object which is an
object of an inter-RAT measurement. For example, the
intra-frequency measurement object may indicate a neighboring cell
having the same frequency band as the serving cell, the
inter-frequency measurement object may indicate a neighboring cell
having a different frequency band from the serving cell, and the
inter-RAT measurement object may indicate a neighboring cell having
different RAT from the serving cell.
[0142] (2) Reporting configuration information: Represents
information on a reporting condition and a report type regarding
when the UE reports the measurement result. The reporting condition
may include information on an event or a cycle that triggers
reporting the measurement result. The report type represents
information regarding in which type the measurement result is
configured.
[0143] (3) Measurement identity information: Represents information
on a measurement identity to decide which measurement object, at a
time when, and in which type the UE reports by associating the
measurement object with the report configuration. The measurement
identity information is included in the measurement report message,
and as a result, it can be seen that for which measurement object
the measurement result is and under which reporting condition the
measurement report occurs.
[0144] (4) Quantity configuration information: Represents
information on a parameter for configuring filtering a measurement
unit, a report unit, and/or a measurement result value.
[0145] (5) Measurement gap information: Represents information on a
measurement gap which is an interval which the UE may use for only
a measurement without considering data transmission with the
serving cell because downlink transmission or uplink transmission
is not scheduled.
[0146] The UE has a measurement object list, a measurement report
configuration list, and a measurement identity list in order to
perform a measurement procedure.
[0147] In the 3GPP LTE, the base station may configure only one
measurement object for one frequency band to the UE. According to
Phrase 5.5.4 of 3GPP TS 36.331 V8.5.0 (2009-03) "Evolved Universal
Terrestrial Radio Access (E-UTRA) Radio Resource Control (RRC);
Protocol specification (Release 8)", events that trigger a
measurement report illustrated in a table described below are
defined.
TABLE-US-00001 TABLE 1 Events Reporting conditions Event A1 Serving
becomes better than threshold Event A2 Serving becomes worse than
threshold Event A3 Neighbour becomes offset better than serving
Event A4 Neighbour becomes better than threshold Event A5 Serving
becomes worse than threshold1 and neighbour becomes better than
threshold2 Event B1 Inter RAT neighbour becomes better than
threshold Event B2 Serving becomes worse than threshold1 and inter
RAT neighbour becomes better than threshold2
[0148] When the measurement result by the UE satisfies the
configured event, the UE transmits the measurement report message
to the base station.
[0149] FIG. 11 illustrates one example of a measurement
configuration configured for the UE.
[0150] First, a measurement identity 1 1101 connects an
intra-frequency measurement object and a report configuration 1 to
each other. The UE performs an intra frequency measurement and the
report configuration 1 is used to decide a criterion and a type of
reporting a measurement result.
[0151] A measurement identity 2 1102 is connected with the
intra-frequency measurement object similarly as the measurement
identity 1 1101, but connects the intra-frequency measurement
object to a report configuration 2. The UE performs the intra
frequency measurement and the report configuration 2 is used to
decide the criterion and the type of reporting the measurement
result.
[0152] The UE transmits the measurement result even though the
measurement result for the intra-frequency measurement object
satisfies any one of the report configuration 1 and the report
configuration 2, by the measurement identity 1 1101 and the
measurement identity 2 1102.
[0153] A measurement identity 3 1103 connects an inter-frequency
measurement object 1 and a report configuration 3 to each other.
When a measurement result for the inter-frequency measurement
object 1 satisfies the reporting condition included in the report
configuration 3, the UE reports the measurement result.
[0154] A measurement identity 4 1104 connects an inter-frequency
measurement object 2 and the report configuration 2 to each other.
When a measurement result for the inter-frequency measurement
object 2 satisfies the reporting condition included in the report
configuration 2, the UE reports the measurement result.
[0155] Meanwhile, the measurement object, the report configuration,
and/or the measurement identity may be added, changed, and/or
deleted. The addition, the change, and/or the deletion may be
instructed by sending a new measurement configuration message or
sending a measurement configuration change message to the UE.
[0156] FIG. 12 illustrates an example of deleting a measurement
identity. When the measurement identity 2 1202 is deleted, a
measurement for a measurement object associated with the
measurement identity 2 1202 is stopped and a measurement report is
not also transmitted. The measurement object or the report
configuration associated with the deleted measurement identity may
not be changed.
[0157] FIG. 13 illustrates an example of deleting a measurement
object. When the inter-frequency measurement object 1 is deleted,
the UE also deletes the associated measurement identity 3 1303. The
measurement for the inter-frequency measurement object 1 is stopped
and the measurement report is not also transmitted. However, the
report configuration associated with the deleted first
inter-frequency measurement object may not be changed or
deleted.
[0158] When the report configuration is removed, the UE removes
even the associated measurement identity. The UE stops measuring
the associated measurement object by the associated measurement
identity. However, the measurement object associated with the
deleted report configuration may not be changed or deleted.
[0159] The measurement report may include the measurement identity,
a measured quality of the serving cell, and a measurement result of
the neighboring cell. The measurement identity identifies a
measurement object in which the measurement report is triggered.
The measurement result of the neighboring cell may include a cell
identity and a measured quality of the neighboring cell. The
measured quality may include at least one of reference signal
received power (RSRP) and reference signal received quality
(RSRQ).
[0160] Subsequently, H(e)NB will be described.
[0161] The mobile communication service may be provided through a
person, a specific operator, or a base station possessed by a group
in addition to the mobile communication network operator. The base
station is called Home NB (HNB) or Home eNB (HeNB). Hereinafter,
both the HNB and HeNB are collectively the HeNB. The HeNB aims at
basically providing a service specialized to only a closed
subscriber group (CSG). However, the service may be provided to
users other than the CSG according to a configuration of an
operating mode of the HeNB.
[0162] FIG. 14 is a diagram illustrating one example of a wireless
communication system illustrating an HeNB operation.
[0163] Referring to FIG. 14, a Home eNB gateway (HeNB GW) may be
operated in order to service the HeNB as such. The HeNBs is
connected to the EPC through the HeNB GW or connected directly to
the EPC. The HeNB GW is seen as a general eNB for the MME. The HeNB
GW is seen as the MME for the HeNB. Therefore, the HeNB and the
HeNB GW are connected to each other through an S1 interface and the
HeNB GW and the EPC are also connected to each other through the S1
interface. Further, even when the HeNB and the EPC are directly
connected to each other, the HeNB and the EPC are connected to each
other through the S1 interface. Most functions of the HeNB are
similar to those of a general eNB.
[0164] In general, the HeNB is lower than an eNB possessed by the
mobile communication operator in radio transmission output.
Therefore, service coverage provided by the HeNB is generally
smaller than that provided by the eNB. Due to such a feature, a
cell provided by the HeNB is often classified as a femto cell as
compared with a macro cell provided by the eNB in terms of the
service coverage. Meanwhile, in terms of the provided service, when
the HeNB provides the service to only the CSG, the cell provided by
the HeNB is called a CSG cell.
[0165] Each CSG has its own unique identification number and the
identification number is called a CSG identity (ID). The UE may
have a list of the CSG to which the UE belongs as a member and the
CSG list may be changed by a request from the UE or a command of
the network. In general, one HeNB may support one CSG.
[0166] The HeNB transfers a CSG ID of a CSG supported thereby
through the system information to be accessed by only the member UE
of the corresponding CSG. When the UE discovers the CSG cell, the
UE may verify which CSG the CSG cell supports by reading the CSG ID
included in the system information. The UE that reads the CSG ID
regards the corresponding cell as a cell capable of access only
when the UE itself is a member of the corresponding CSG cell.
[0167] Even the HeNB need not permit only the CSG UE to access
itself. The HeNB may also permit a UE which is not the CSG member
to access itself according to a configuration of the HeNB. Which UE
the HeNB permits to access itself depends on the configuration of
the HeNB and herein, the configuration means a configuration of an
operating mode of the HeNB. The operating mode of the HeNB is
divided into three types described below by considering which UE
the HeNB provides the service to.
[0168] Closed access mode: Represents a mode to provide the service
to a specific CSG member. The HeNB provides the CSG cell.
[0169] Open access mode: Represents a mode to provide the service
without a limitation of the specific CSG member like a general eNB.
The HeNB provides not the CSG cell but the general cell.
[0170] Hybrid access mode: Represents a mode to provide a CSG
service to the specific CSG member and provide the service to even
a non-CSG member like the general cell. Recognized as the CSG cell
by the CSG member UE and recognized as the general cell by the
non-CSG member UE. Such a cell is called a hybrid cell.
[0171] The HeNB notifies whether a cell serviced thereby is the CSG
cell or the general cell to the UE to allow the UE to know whether
the UE may access the corresponding cell. The HeNB operated in the
closed access mode broadcasts that the HeNB itself is the CSG cell
through the system information. The HeNB operated in the open
access mode broadcasts that the HeNB itself is not the CSG cell
through the system information. As such, the HeNB encapsulates a
1-bit CSG indicator indicating whether the cell serviced thereby is
the CSG cell in the system information. For example, the HeNB
broadcasts that the serviced cell is the CSG cell by setting the
CSG indicator as TRUE. If the serviced cell is not the CSG cell,
the CSG indicator may be set as FALSE or a method that skips
transmitting the CSG indicator may be used. Since the UE needs to
be able to distinguish the general cell provided by the eNB from
the CSG cell, the general eNB also transmit the CSG indicator to
allow the UE to know that the cell type provided thereby is the
general cell. The general eNB does not transmit the CSG indicator
to allow the UE to know that the cell type provided thereby is the
general cell. Table 2 illustrates a CSG associated parameter
transmitted in a corresponding cell for each cell type.
Subsequently, Table 3 illustrates a type of a UE that permits the
access for each cell type.
TABLE-US-00002 TABLE 2 CSG cell General cell CSG indicator
Indicating `CSG cell` Indicating `Non-CSG cell` or not transmitted
CSG identity Transmitting supported Not transmitted CSG
identity
TABLE-US-00003 TABLE 3 CSG cell General cell UE not supporting CSG
Inaccessible Accessible Non-CSG member UE Inaccessible Accessible
Member CSG UE Accessible Accessible
[0172] Hereinafter, inter-cell interference coordination (ICIC)
will be described.
[0173] The ICIC is a task that operates a radio resource so that a
control of inter-cell interference is maintained. An ICIC mechanism
may be divided into frequency-domain ICIC and time-domain ICIC. The
ICIC has a multi-cell radio resource management (RRM) function to
require considering information from multiple cells.
[0174] An interfering cell is a cell that provides interference.
The interfering cell is also referred as an aggressor cell.
[0175] An interfered cell is a cell that is interfered by the
interfering cell. The interfered cell is also referred to as a
victim cell.
[0176] The frequency-domain ICIC coordinates the use of a
frequency-domain resource (e.g., a resource block (RB)) among the
multiple cells.
[0177] The time-domain ICIC coordinates a time-domain resource
(e.g., a subframe) among the multiple cells. An operations,
administration, and maintenance (OAM) configuration called an
almost blank subframe (ABS) pattern may be used for the time-domain
ICIC. An ABS in the interfering cell is used to protect a resource
in the subframe in the interfered cell that receives interference
among strong cells. The ABS is a subframe that has reduced
transmission power (alternatively, zero transmission power) on the
physical channel or has reduced activity.
[0178] A pattern based on the ABS is notified to the UE and
restricts a UE measurement. This restriction is referred to as a
measurement resource restriction. The ABS pattern represents
information indicating which subframe is the ABS in one or more
radio frames.
[0179] There are provided three measurement resource restriction
patterns according to a measured cell (e.g., a serving cell or a
neighbor cell) and measurement types (e.g., a radio resource
management (RRM), a radio link measurement (RLM), and channel state
information (CSI)).
[0180] `ABS pattern 1` is used in an RRM/RLM measurement resource
restriction of the serving cell. The base station may notify
information on ABS pattern 1 to the UE in
configuration/modification/release of the RB or when MAC/PHY
configuration is modified.
[0181] `ABS pattern 2` is used in an RRM measurement resource
restriction of the neighbor cell that operates at the same
frequency as the serving cell. Therefore, a list of neighbor cells
to be measured in addition to information on ABS pattern 2 may be
provided to the UE. ABS pattern 2 may be included in a measurement
configuration for a measurement object.
[0182] `ABS pattern 3` is used in a resource restriction for a CSI
measurement of the serving cell. ABS pattern 3 may be included in a
message for configuring a CSI report.
[0183] Two scenarios of a CSG scenario and a pico scenario are
considered for the ICIC.
[0184] FIG. 15 exemplifies a CSG scenario.
[0185] The CSG cell represents a cell accessible by only a specific
subscriber. The non-member UE as a UE which is not the member of
the CSG cell is UE that does not access the CSG cell. The CSG cell
which the UE may not access is referred to as the non-member CSG
cell. The macro cell represents the serving cell of the non-member
UE. Coverage of the CSG cell and coverage of the macro cell are
partially or fully duplicated with each other.
[0186] A primary interference condition occurs when the non-member
UE is positioned in close proximity with the CSG cell. In terms of
the non-member UE, the interfering cell becomes the CSG cell and
the macro cell becomes the interfered cell. The time-domain ICIC is
used so as for the non-member UE to continuously receive the
service in the macro cell.
[0187] In the RRC connection state, when the network discovers that
the non-member UE belongs to strong interference from the CSG cell,
the network may configure a measurement resource restriction.
Further, in order to facilitate mobility from the macro cell, the
network may configure an RRM measurement resource restriction for
the neighbor cell. When the UE is not strongly interfered from the
CSG cell any longer, the network may release the RRM/RLM/CSI
measurement resource restriction.
[0188] The UE may use the measurement resource restrictions
configured for the RRM, RLM, and CSI measurement. That is, a
resource for the RLM may be used in the ABS, and the measurement
for the RLM and the CSI measurement may be performed in the
ABS.
[0189] The network may configure the CSG cell not to use a
low-interference radio resource depending on the configured
measurement resource restriction. That is, the CSG cell may not
transmit or receive data in the ABS.
[0190] FIG. 16 exemplifies a pico scenario.
[0191] A pico cell is a serving cell of a pico UE. The pico cell is
a cell of which coverage is partially or fully duplicated with the
coverage of the macro cell. The pico cell may generally have
smaller coverage than the macro cell, but the present invention is
not particularly limited thereto.
[0192] The primary interference condition occurs when the pico UE
is positioned at an edge of the pico serving cell. In terms of the
pico UE, the interfering cell becomes the macro cell and the pico
cell becomes the interfered cell. The time-domain ICIC is used so
as for the pico UE to continuously receive the service in the pico
cell.
[0193] When the pico cell discovers that the pico UE is strongly
interfered from the macro cell, the pico cell may configure the
measurement resource restriction for the corresponding UE.
[0194] The pico UE may use the measurement resource restrictions
configured for the RRM, RLM, and CSI measurement. That is, the
resource for the RLM may be used in the ABS, and the measurement
for the RLM and the CSI measurement may be performed in the ABS.
When the pico cell is strongly interfered from the macro cell, a
more accurate measurement is possible in the case where the
RRM/RLM/CSI measurement is performed in the ABS.
[0195] Further, when the UE in the macro cell as the serving cell
performs the measurement for the neighbor cell in the ABS, mobility
from the macro cell to the pico cell may be facilitated.
[0196] The UE performs the RRM measurement such as the reference
signal received power (RSRP) and the reference signal received
quality (RSRQ), a measurement of quality such as a channel quality
indicator (CQI), and a path-loss measurement for the serving cell
or the neighbor cell. Further, the UE may perform a measurement for
radio link monitoring (RLM) for monitoring a connection with the
serving cell.
[0197] The interfering cell and the interfered cell are decided
depending on an object which the UE intends to measure.
[0198] When the UE intends to measure the serving cell, an
intra-frequency neighbor cell having a high signal strength near
the UE may act as interference in a measurement for the serving
cell. In this case, the UE may undergo strong interference by the
neighbor cell in the measurement for the serving cell.
[0199] When the UE intends to measure the intra-frequency neighbor
cell, serving cell and other intra-frequency neighbor cell signals
may act as the interference for the measurement of the
intra-frequency neighbor cell. In this case, the UE may undergo
strong interference by the serving cell and other neighbor cells of
a serving frequency in the measurement of the neighbor cell.
[0200] When the serving cell may know information on a measurement
resource restriction which the neighbor cell causing the UE to be
interfered applies for suppressing the interference, the interfered
UE may perform a limited measurement based on the measurement
resource restriction. The serving cell may provide the service the
UE through scheduling primarily using a low-interference radio
resource in spite of the interference by the neighbor cell.
[0201] A multimedia broadcast/multicast service (MBMS) is a service
to provide multimedia data to the UE in the cell. An MCH channel
which is a transmission channel for the MBMS may be mapped to the
MCCH or the MTCH which is the logical channel. The MCCH transmits
an RRC message associated with the MBMS and the MTCH transmits
traffic of a specific MBMS.
[0202] A plurality of MCHs may be used according to capacities of
the MTCH and the MCCH in one cell. The MCH is in charge of
transmitting two logical channels of the MTCH and the MCCH, and is
again mapped to a physical multicast channel (PMCH) which is the
physical channel.
[0203] One MCCH is present in one MBMS single frequency network
(MBSFN) region transmitting the same MBMS information/traffic, and
when a plurality of MBSFN regions are provided in one cell, the UE
may receive a plurality of MCCHs. When the MBMS associated RRC
message is changed in a specific MCCH channel, the PDCCH transmits
an MBMS radio network temporary identity (M_RNTI) and an indicator
indicating the specific MCCH.
[0204] A UE that supports the MBMS receives the M-RNTI and the MCCH
indicator through the PDCCH to determine that the MBMS associated
RRC message is changed in the specific MCCH and receive the
specific MCCH. The RRC message of the MCCH may be changed every
change cycle and is repeatedly broadcasted every repetition
cycle.
[0205] The existing wireless network may calculate the number of
UEs that receives a specific service through a counting procedure.
The counting procedure is configured in such a manner that the UE
transmits an uplink counting response message when the wireless
network transmits a downlink counting request message.
[0206] When a UE receives a request for reporting system
information of a neighboring cell from a serving cell, the UE
temporarily acquires the system information of the neighboring cell
by accessing the neighboring cell by leaving the serving cell.
Thereafter, the UE performs a procedure of reporting neighboring
cell information to the serving cell by accessing the serving cell
again. While the UE leaves the serving cell in order to acquire the
system information, the UE corresponds to an unreachable object
from the viewpoint of the serving cell, and as a result, the
serving cell may not transfer even any command/message/data to the
UE.
[0207] In the case of a specific handover, the serving cell
requests system information of a handover target cell to the UE. A
long time may elapse until the UE receives the system information
of the neighboring cell and reports the received system information
to the serving cell. As a result, a problem in which the handover
is delayed may occur.
[0208] Meanwhile, the UE may have already had system information of
a corresponding neighboring cell before receiving a request for
reporting the system information of the neighboring cell from the
serving cell. If the system information of the neighboring cell is
valid even when reporting the system information is requested,
separately acquiring the system information by accessing the
neighboring cell may be an unnecessary procedure. In this case, the
UE may transmit the system information of the neighboring cell
which the UE has already had to the serving cell, and as a result,
an effect to rapidly perform the handover may be brought through
rapid reporting of the system information. Hereinafter, the method
for reporting system information will be described in more
detail.
[0209] FIG. 17 is a flowchart illustrating an operation of a UE
that performs the method for reporting system information according
to an embodiment of the present invention.
[0210] Referring to FIG. 17, the UE receives a system information
reporting request to request reporting the system information of
the neighboring cell from the serving cell (S1710).
[0211] The UE determines whether there is system information of the
neighboring cell which is acquired in advance. The procedure of
determining whether there is the system information which is
acquired in advance may include a step of determining whether the
UE has the system information which is obtained in advance before
receiving the request for reporting the system information and a
step of determining whether the corresponding system information is
valid when there is the system information of the neighboring cell
which has already been obtained.
[0212] Whether the system information of the neighboring cell which
is obtained in advance is valid may be determined depending on a
time elapsed from the time when the system information is obtained.
When the elapsed time is more than a specific value, it may be that
the corresponding system information is not valid any longer.
[0213] The UE reports the corresponding system information to the
serving cell when there is the system information regarding the
neighboring cell acquired in advance, to be reported to the serving
cell (S1730).
[0214] The UE acquires the system information from the neighboring
cell when there is no system information of the neighboring cell to
be reported to the serving cell (S1740). The UE accesses the
neighboring cell by temporally leaving the serving cell in order to
acquire the system information of the neighboring cell. The UE may
acquire the system information of the neighboring cell through a
broadcast channel by accessing the neighboring cell.
[0215] The UE reports the system information acquired by accessing
the serving cell to the serving cell again (S1750).
[0216] The UE receives a request for reporting the system
information of the neighboring cell from the serving cell, and when
the UE reports the system information which is acquired in advance
before the request, the UE may transmit control information
regarding the corresponding system information to the serving cell
together with the system information reporting message. The control
information may include an indicator indicating that the
corresponding system information is the system information which is
acquired in advance before the reporting request and an indicator
associated with an acquisition time.
[0217] FIG. 18 is a flowchart illustrating one example of a method
for reporting system information according to an embodiment of the
present invention. Referring to FIG. 18, it is assumed that the UE
has already had system information of neighboring cell A and does
not have system information of neighboring cell B.
[0218] Referring to FIG. 18, the UE receives a system information
reporting request to request reporting the system information of
neighboring cell A from the serving cell (S1810).
[0219] Since the UE has the system information of neighboring cell
A, the UE reports the system information of neighboring cell A to
the serving cell (S1820). The UE may transmit to the serving cell
both the system information of neighboring cell A and the control
information regarding the system information. The control
information may include an indicator indicating that the
corresponding system information is the system information acquired
in advance before receiving the system information reporting
request. The control information may include an indicator
indicating the time when the system information was acquired.
[0220] The UE receives a system information reporting request to
request reporting the system information of neighboring cell B from
the serving cell (S1830).
[0221] Since the UE does not have the system information of
neighboring cell B, the UE acquires the system information by
accessing neighboring cell B (S1840).
[0222] The UE acquires the system information of neighboring cell B
and thereafter, reports the acquired system information to the
serving cell (S1850). Since the system information of cell B is
newly acquired after receiving the system information reporting
request, the control information regarding the corresponding system
information may not be transmitted together. On the contrary, the
system information of cell B may be transmitted together with the
control information, and in this case, the control information may
include an indicator that the system information of cell B is the
system information obtained after receiving the system information
reporting request and/or an indicator indicating the time when the
corresponding system information is acquired.
[0223] The UE may store system information of a specific
neighboring cell for a specific time or more in order to perform
the system information reporting method according to the embodiment
of the present invention. When the UE receives system information
of a cell which a specific user frequently visits, for example, a
cell installed in a home of the user or a cell installed in a
company, the UE may store the system information of the cell in
order to report the system information of the cell afterwards. In
the present invention, when the UE stores the system information
for the purpose of reporting the system information, the UE may be
allowed to store the system information for a time which is more
than a valid time of general system information.
[0224] Meanwhile, the serving cell may indicate to the UE whether
system information is allowed to be transmitted when the
corresponding system information obtained in advance regarding a
specific neighboring cell exists. To this end, the serving cell may
transmit to the UE a ready-acquired system information report
indicator together with the system information reporting request.
When the ready-acquired system information report indicator is
used, the UE may report the system information to the serving cell
based thereon. A method for reporting system information based on
the ready-acquired system information report indicator will
hereinafter be described in detail.
[0225] FIG. 19 illustrates an operating flowchart of a UE that
performs the method for reporting system information according to
an embodiment of the present invention.
[0226] Referring to FIG. 19, the UE receives a system information
reporting request to request reporting system information of a
neighboring cell from the serving cell (S1910).
[0227] The UE determines whether to report system information which
is acquired in advance, based on the ready-acquired system
information report indicator included in the system information
reporting request (S1920). When the ready-acquired system
information report indicator is not included in the system
information reporting request, the UE may determine that reporting
the system information which is acquired in advance is not allowed.
Further, when the ready-acquired system information report
indicator is included in the system information reporting request,
the UE may determine that reporting the information which is
acquired in advance is allowed. Alternatively, when the
ready-acquired system information report indicator is included in
the system information reporting request and the indicator is set
to indicate that the system information which is acquired in
advance is allowed, the UE may determine that reporting the system
information which is acquired in advance is allowed.
[0228] When reporting the system information which is acquired in
advance is not allowed, the UE acquires the system information from
the neighboring cell (S1930). The UE accesses the neighboring cell
by temporally leaving the serving cell in order to acquire the
system information of the neighboring cell. The UE may acquire the
system information of the neighboring cell through a broadcast
channel by accessing the neighboring cell.
[0229] The UE reports the system information acquired by accessing
the neighboring cell to the serving cell (S1940).
[0230] When reporting the system information which is acquired in
advance is allowed, the UE determine whether there is system
information which is acquired in advance, to be reported to the
serving cell (S1950). Determining whether there is the system
information which is acquired in advance may include a step of
determining whether the UE has the system information which is
acquired in advance before receiving the request for reporting the
system information and a step of determining whether the
corresponding system information is valid when there is the system
information of the neighboring cell which has already been
acquired.
[0231] Whether the system information of the neighboring cell which
is acquired in advance is valid may be determined depending on a
time elapsed from the time when the system information is acquired.
When the elapsed time is more than a specific value, it may be that
the corresponding system information is not valid any longer.
[0232] The UE reports the corresponding system information to the
serving cell when there is the system information regarding the
neighboring cell acquired in advance (S1960).
[0233] The UE acquires the system information from the neighboring
cell when there is no system information of the neighboring cell
obtained in advance, to be reported to the serving cell (S1930).
The UE accesses the neighboring cell by temporally leaving the
serving cell in order to acquire the system information of the
neighboring cell. The UE may acquire the system information of the
neighboring cell through a broadcast channel by accessing the
neighboring cell.
[0234] The UE reports the system information acquired by accessing
the neighboring cell to the serving cell (S1940).
[0235] FIG. 20 is a flowchart illustrating one example of a method
for reporting system information according to an embodiment of the
present invention. It is assumed that the UE has already had system
information of neighboring cell A and system information of
neighboring cell B to be reported.
[0236] Referring to FIG. 20, the UE receives a system information
reporting request to request reporting the system information of
neighboring cell A from the serving cell (S2010). The system
information reporting request includes a ready-acquired system
information report indicator indicating that the UE may report the
system information of neighboring cell A which is acquired in
advance.
[0237] The UE receives the system information reporting request
from the serving cell and verifies that it is allowed to report the
system information of neighboring cell A which is acquired in
advance. In response thereto, the UE reports to the serving cell
the system information of neighboring cell A which is acquired in
advance (S2020).
[0238] The UE receives a system information reporting request to
request reporting the system information of neighboring cell B from
the serving cell (S2030). The system information reporting request
may include a ready-acquired system information report indicator
indicating that reporting the system information of neighboring
cell which the UE obtains in advance is not allowed or the system
information reporting request may not include a ready-acquired
system information report indicator.
[0239] The UE receives the system information reporting request
from the serving cell and verifies that it is not allowed to report
the system information of neighboring cell B which is acquired in
advance. The UE acquires the system information by accessing
neighboring cell B (S2040).
[0240] The UE acquires the system information of neighboring cell B
and thereafter, reports the acquired system information to the
serving cell (S2050).
[0241] The embodiments regarding the system information reporting
methods are combined with each other to be implemented with
reference to FIGS. 17 to 20. That is, the UE may determine whether
to report the system information by being indicated whether
reporting the system information which is acquired in advance is
allowed from the serving cell. Further, the UE may encapsulate and
report the control information regarding the corresponding system
information, in reporting specific system information to the
serving cell.
[0242] FIG. 21 is a diagram illustrating another example of the
method for reporting system information according to an embodiment
of the present invention. It is assumed that the UE has already had
the system information of neighboring cell A and the system
information of neighboring cell B. It is assumed that the UE does
not have system information of neighboring cell C.
[0243] Referring to FIG. 21, the UE receives a system information
reporting request to request reporting the system information of
neighboring cell A from the serving cell (S2110). The system
information reporting request includes a ready-acquired system
information report indicator indicating that the UE may report the
system information of neighboring cell A which is acquired in
advance.
[0244] The UE receives the system information reporting request
from the serving cell and verifies that it is allowed to report the
system information of neighboring cell A which is acquired in
advance. In response thereto, the UE reports to the serving cell
the system information of neighboring cell A which is acquired in
advance (S2120). The UE transmits to the serving cell the control
information regarding the system information together in reporting
the system information of cell A. The control information may
include an indicator indicating that the system information is the
system information which is acquired in advance before receiving a
request for reporting the system information of neighboring cell A.
The control information may include an indicator indicating the
time when the system information is acquired.
[0245] The UE receives a system information reporting request to
request reporting the system information of neighboring cell B from
the serving cell (S2130). The system information reporting request
may include a ready-acquired system information report indicator
indicating that the UE may report the system information of
neighboring cell B which is acquired in advance is not allowed.
Alternatively, the system information reporting request may not
include a separate ready-acquired system information report
indicator.
[0246] The UE receives the system information reporting request
from the serving cell and verifies that it is not allowed to report
the system information of neighboring cell B which is acquired in
advance. The UE acquires the system information by accessing
neighboring cell B (S2140).
[0247] The UE obtains the system information of neighboring cell B
and thereafter, reports the acquired system information to the
serving cell (S2150). The UE transmits to the serving cell the
control information regarding the system information together in
reporting the system information of cell B. In this case, the
control information may include an indicator indicating that the
system information is newly acquired after receiving a request for
reporting the system information of neighboring cell B.
Alternatively, the control information may not be included. The
serving cell may determine that the corresponding system
information is system information which is acquired after the
system information reporting request when separate control
information is not included.
[0248] The UE receives a system information reporting request to
request reporting the system information of neighboring cell C from
the serving cell (S2160). The system information reporting request
includes a ready-acquired system information report indicator
indicating that the UE may report the system information of
neighboring cell C which is acquired in advance.
[0249] The UE receives the system information reporting request
from the serving cell and verifies that it is allowed to report the
system information of neighboring cell C which is acquired in
advance. However, since the UE does not have the system information
of neighboring cell C, the UE acquires the system information by
accessing neighboring cell C (S2170).
[0250] The UE acquires the system information of neighboring cell C
and thereafter, reports the acquired system information to the
serving cell (S2180). The UE may transmit to the serving cell the
control information regarding the system information together in
reporting the system information of cell C. In this case, the
control information may indicate that the system information is
newly acquired after receiving a request for reporting the system
information of neighboring cell C. Alternatively, the control
information may not be included. The serving cell may determine
that the corresponding system information is system information
which is acquired after the system information reporting request
when separate control information is not included.
[0251] In the embodiments by referring to FIGS. 17 to 21, the
system information reporting request may be transmitted to the UE
through a measurement setting message. Further, a system
information report may be transmitted to the UE through a
measurement reporting message.
[0252] In the embodiment of the system information reporting
method, the system information which the UE reports to the serving
cell may include information described below.
[0253] When a cell associated with the system information is a cell
that supports a CSG, the reported system information may include
CSG associated information such as a CSG ID and a CSG indicator of
the cell.
[0254] When the cell associated with the system information is a
cell that supports an MBMS, the reported system information may
include MBMS associated information such as MBMS information, MBMS
configuration information, MBMS scheduling information, MBMS
providing frequency information, and/or MBSFN subframe information
of the cell.
[0255] When the cell associated with the system information is a
cell in which the measurement resource restriction is configured,
the reported system information may include ABS pattern information
of the cell, low-interference subframe pattern information, or
low-interference radio resource associated information such as a
limited measurement pattern.
[0256] The reported system information may include access
restriction associated information such as an access class barring
parameter.
[0257] The reported system information may be frequency band
information of one or more uplinks associated with a downlink of
the specific cell.
[0258] In the embodiments of the present invention described with
reference to FIGS. 17 to 21, when the serving cell requests
reporting the system information of the neighboring cell, the
serving cell may transfer to the UE a system information indicator
indicating that specific information will be transported in the
system information of the neighboring cell. The system information
indicator may be implemented in such a manner that one system
information indicator indicates one or more types of information to
request reporting the corresponding information. The system
information indicator may be implemented in such a manner that one
indicator indicates a specific type of information to request
reporting one or more specific types of information through
transmitting one or more system information indicators.
[0259] The system information indicator is included in a
measurement configuration to be transmitted, and may be transmitted
together with the system information reporting request. The system
information report indicator may be included in a measurement
object configuration and/or a measurement report configuration. The
system information which is requested to be reported may be at
least one of CSG associated information, MBMS associated
information, low-interference radio resource associated
information, access restriction associated information, and
frequency band information of one or more uplinks associated with a
downlink of a specific cell.
[0260] In the embodiments of the present invention described in
detail with reference to FIGS. 17 to 21, the UE may transmit to the
serving cell specific information judged/processed based on the
corresponding system information in reporting to the serving cell
system the system information which is acquired in advance and/or
system information which is newly acquired after the system
information reporting request.
[0261] The specific information may include information indicating
whether a UE associated with the corresponding neighboring cell is
a CSG member.
[0262] The specific information may include information indicating
whether the UE may access the corresponding neighboring cell.
[0263] The specific information may include information indicating
whether to receive a specific service desired by the UE in the
corresponding neighboring cell. As one example, the specific
information may include information indicating whether the UE may
receive a service for MBMS information in the cell.
[0264] The specific information may be information indicating
whether the UE may be subjected to a specific radio resource
configuration in the corresponding neighboring cell. For example,
the specific information may be information indicating whether the
UE may camp on in the cell. The specific information may be
information indicating whether the cell is a suitable cell for the
UE. The specific information may be information indicating whether
the cell is a cell used as the serving cell through carrier
aggregation or system information required to configure the cell as
the serving cell through the carrier aggregation.
[0265] The specific information may information representing
whether the corresponding neighboring cell is a cell which the UE
may use as an additional serving cell (Pcell or Scell).
[0266] Through the method for reporting system information
described in detail with reference to FIGS. 17 to 21, a time used
for a UE to report system information of a neighboring cell to a
serving cell can be decreased. Therefore, a handover delay of a
handover procedure requiring system information of a target cell
can be decreased. Further, a procedure in which the UE
unnecessarily receives the system information of the neighboring
cell is skipped, and as a result, a time when the serving cell
loses controllability of the UE can be decreased.
[0267] FIG. 22 is a block diagram illustrating a wireless apparatus
which may be implemented by the embodiment of the present
invention. A UE and/or a base station that performs the system
information reporting method according to the embodiment of FIGS.
17 and 21 may be implemented by the apparatus.
[0268] A wireless apparatus 2200 includes a processor 2210, a
memory 2220, and a radio frequency unit (RF unit) 2230. The
processor 2210 implements a function, a process, and/or a method
which are proposed. The processor 2210 may be configured to report
the system information of the neighboring cell to the serving cell
in response to the system information reporting request. The
processor 2210 may be configured to determined whether reporting
the system information which is acquired in advance is allowed. The
processor 2210 may be configured to report the corresponding system
information to the serving cell when reporting the system
information which is obtained in advance is allowed and the system
information which is acquired in advance exists. The processor 2210
may be configured to transmit the control information indicating
whether the corresponding system information is the system
information which is acquired in advance together in reporting the
system information to the serving cell. The processor 2210 may be
configured to implement the embodiment of the present invention
associated with the system information reporting method described
in detail with reference to FIGS. 17 and 21.
[0269] The RF unit 2230 is connected with the processor 2210 to
transmit and/or receive a radio signal.
[0270] The processor 2210 may include an application-specific
integrated circuit (ASIC), another chip set, a logic circuit and/or
a data processing apparatus. The memory 2220 may include a
read-only memory (ROM), a random access memory (RAM), a flash
memory, a memory card, a storage medium, and/or another storage
device. The RF unit 2230 may include a baseband circuit for
processing the radio signal. When the embodiment is implemented by
software, the aforementioned technique may be implemented by a
module (a process, a function, and the like) that performs the
aforementioned function. The module may be stored in the memory
2220 and executed by the processor 2210. The memory 2220 may be
provided inside or outside the processor 2210 and connected with
the processor 2210 by various well-known means.
[0271] In the aforementioned exemplary system, methods have been
described based on flowcharts as a series of steps or blocks, but
the methods are not limited to the order of the steps of the
present invention and any step may occur in a step or an order
different from or simultaneously as the aforementioned step or
order. Further, it can be appreciated by those skilled in the art
that steps shown in the flowcharts are not exclusive and other
steps may be included or one or more steps do not influence the
scope of the present invention and may be deleted.
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