METHOD FOR INTERFERENCE COORDINATION OF FEMTOCELLS,
FEMTOCELL AND USER TERMINAL EQUIPMENT
Field of the Invention
The present invention relates to the mobile communication filed, and more specifically,
to a method for inter-cell interference coordination in the mobile communication field.
Background of the Invention
Recently, experiment networks for the Long Term Evolution (LTE for short) system of
the mobile communication network has begun to be deployed all around the world, and it is
about to provide services to the masses in the near future. In a LTE wireless network, in
addition to traditional macrocells, microcells, there may also be deployed a number of
picocells, femtocells, wireless relays and various other wireless network access nodes whose
transmitting powers and coverage ranges are significantly varied. Introduction of such new
nodes makes the future network a heterogeneous network with various kinds of wireless
access nodes competing for wireless resources, which has a topology structures more complex
than that of a traditional homogeneous network. This forms a totally new wireless interference
environment.
The femtocells may significantly improve indoor coverage of the LTE system in that it
may provide users with excellent access services. A femtocell has three work modes: open
mode, closed mode and mixed mode. As a private device, a user generally will choose the
closed mode for it, that is to say, only authorized users such as family members, party
members are permitted to access. These authorized users are named as "closed subscriber
group" (CSG for short). However, a user equipment terminal for a macrocell is unable to
connect to a femtocell defined by a "closed subscriber group". A cell covered by a femtocell is
called a CSG cell as compared to a macro cell covered by a macro base station. Since the
users may independently adjust the transmitting powers of femtocells, independently change
positions of femtocells, and arbitrarily open or close the femtocells, the interferences between
CSG cells and macrocells become an important interference scenario in the LTE system.
A general macro-femto deployment scenario in the LTE system is shown in FIG. 1. A
femtocell is deployed in the coverage region of a macrocell. When a user terminal of the
macrocell moves into the coverage range of the femtocell, the user equipment terminal of the
macrocell is unable to connect to the femtocell defined by a "closed subscriber group" in this
scenario since the femtocell is a private device. Therefore, for the user equipment terminal of
the macrocell, there will be a "dead zone" in which control and data channels are unable to be
detected.
As mentioned above, the inter-cell interference problem in the LTE network is always
an important consideration in this industry. The LTE international standard has proposed some
inter-cell interference coordination technologies whose basic ideas are all to perform physical
resource allocation coordination between adjacent cells in order to reduce inter-cell
interferences as much as possible. In particular, these technologies can be categorized into
time domain solutions, power control solutions and frequency domain solutions. The key point
in the time domain solutions is to coordinate utilization of time domain resources between the
interfering nodes and the interfered nodes to make them orthogonal. The power control
solutions reduce the interference level by adjusting the transmitting powers of the interfering
nodes and the interfered nodes. The frequency domain solutions avoid interferences by
configuring orthogonal frequency resources for the physical resources occupied by the control
channels. So far, all interference coordination methods such as power control and time domain
resource allocation for the macrocell-femtocell deployment scenario are all based on the
measurement by users. However, since the user terminal of the macrocell is unable to connect
to the femtocell set to the closed mode in this scenario, there will be a "dead zone" in which
control and data channels are unable to be detected by the user terminal of the macrocell. This
problem will become worse especially when the user terminal of the macrocell is powered on
after moving into the dead zone, since it is unable to detect the change of the channel quality
of the serving cell and thus it is unable to trigger the interference coordination between the
femtocell and the macrocell. In this case, the user terminal of the macrocell will not be able to
communicate with the femtocell unless the user terminal goes out of the dead zone.
In view of the problem existed in the interference coordination technologies in the
macrocell-femtocell deployment scenario of a LTE system, the invention proposes an
enhanced inter-cell interference coordination method. With this method, the femtocell can
identify presence of user terminal of the macrocell and then trigger a method for power control
and time domain resource allocation.
Summary of the Invention
The present invention proposes a femtocell interference coordination method, a
femtocell and a user terminal equipment in a macro-femtocell deployment scenario. The key
point of this invention is to stimulate a user terminal of a macrocell to initiate a random access
request to a femtocell defined by a "closed subscriber group". Based on this, the femtocell will
know there is a user that can not be detected by the macrocell and then trigger corresponding
interference coordination operation to ensure that the user terminal equipment of the
macrocell can at least receive information of control channels correctly.
In particular, according to an embodiment of the present invention, there is provided a
method for interference coordination by a femtocell, wherein there is at least one user terminal
of a macrocell within coverage of the femtocell. The method comprises:
the femtocell receiving a random access request initiated by the user terminal of the
macrocell;
the femtocell estimating path loss between the femtocell and the user terminal of the
macrocell; and
the femtocell performing interference coordination to ensure that the user terminal of
the macrocell can receive information of control channels correctly.
According to a specific embodiment of the present invention, the femtocell receiving a
random access request initiated by the user temiinal of the macrocell further comprises:
synchronizing the user temiinal of the macrocell to the femtocell;
the user temiinal of the macrocell receiving system information of the femtocell,
system information of the femtocell indicating that the user temiinal of the macrocell can
access the femtocell; and
the user temiinal of the macrocell initiating the random access request to the femtocell.
According to a specific embodiment of the present invention, the femtocell receiving a
random access request initiated by the user temiinal of the macrocell further comprises:
updating information settings of "whitelist of closed subscriber groups" of the user
terminal of the macrocell to comprise all femtocells that potentially cause interferences to the
user temiinal of the macrocell;
synchronizing the user temiinal of the macrocell to the femtocell; and
the user terminal of the macrocell initiating the random access request to the femtocell.
According to a specific embodiment of the present invention, the femtocell receiving a
random access request initiated by the user temiinal of the macrocell further comprises:
synchronizing the user temiinal of the macrocell to the femtocell; and
the user temiinal of the macrocell receiving an instruction from a user to initiate the
random access request to the femtocell.
According to a specific embodiment of the present invention, a BOOLEAN
information indication of csg-indication in information block 1 of the system information of the
femtocell is set to be "FALSE".
According to a specific embodiment of the present invention, the information settings
of "whitelist of closed subscriber groups" of the user terminal of the macrocell is obtained
through information from a network side, or obtained through empirical information of a user
terminal side, and it is updated through a radio resource control connection.
According to a specific embodiment of the present invention, the femtocell estimates
the path loss between the femtocell and the user temiinal of the macrocell based on a default
transmitting power value of the user temiinal of the macrocell.
According to a specific embodiment of the present invention, the femtocell performs
the interference coordination based on power control or time domain resource allocation.
According to a specific embodiment of the present invention, the femtocell performs
the interference coordination based on the path loss between the femtocell and the user
temiinal of the macrocell and the path loss between the femtocell and the macrocell estimated
by the femtocell.
According to a specific embodiment of the present invention, there is provided a
method for initiating a random access to a femtocell by a user temiinal, wherein the user
temiinal is a user temiinal of a macrocell and is located in coverage area of the femtocell, and
the user temiinal of the macrocell is an unauthorized user temiinal for the femtocell. The
method comprises:
the user temiinal obtaining information allowing initiation of a random access request
to the femtocell; and
the user temiinal initiating the random access request to the femtocell.
According to a specific embodiment of the present invention, the user temiinal
obtaining information allowing initiation of a random access request to the femtocell includes:
the user temiinal receiving system information from the femtocell, the system information of
the femtocell indicating that the user temiinal of the macrocell can access the femtocell
According to a specific embodiment of the present invention, the user temiinal
obtaining information allowing initiation of a random access request to the femtocell includes:
information settings of "whitelist of closed subscriber groups" of the user terminal of the
macrocell comprising all femtocells that potentially cause interferences to the user terminal of
the macrocell.
According to a specific embodiment of the present invention, the user temiinal
obtaining information allowing initiation of a random access request to the femtocell includes:
the user temiinal receiving from a user an instruction which instructs the user equipment to
initiate the random access request to the femtocell.
According to a specific embodiment of the present invention, a BOOLEAN
information indication of csg-indication in information block 1 of the system information of the
femtocell is set to be "FALSE".
According to a specific embodiment of the present invention, the information settings
of "whitelist of closed subscriber groups" of the user terminal of the macrocell is obtained
through information from a network side, or obtained through empirical information of a user
terminal side, and it is updated through a radio resource control connection.
According to a specific embodiment of the present invention, there is provided a
femtocell, where there is at least one user temiinal of a macrocell within coverage range of the
femtocell. The femtocell comprises:
a synchronizing unit configured to receive synchronization information from the user
temiinal of the macrocell within the coverage range of the femtocell;
a receiving unit configured to receive a random access request initiated from the user
temiinal of the macrocell;
a path loss estimating unit configured to estimate path loss from the user temiinal of
the macrocell to the femtocell and path loss from the macrocell to the femtocell; and
an interference coordination unit configured to perform interference coordination to
ensure that the user temiinal of the macrocell can receive information of control channels
correctly.
According to a specific embodiment of the present invention, the path loss estimating
unit estimates the path loss between the femtocell and the user temiinal of the macrocell based
on a default transmitting power value of the user temiinal of the macrocell.
According to a specific embodiment of the present invention, the interference
coordination unit performs the interference coordination based on power control or time
domain resource allocation.
According to a specific embodiment of the present invention, the interference
coordination unit performs the interference coordination based on the path loss between the
femtocell and the user temiinal of the macrocell and the path loss between the femtocell and
the macrocell estimated by the femtocell.
According to a specific embodiment of the present invention, the femtocell further
includes a system information setting unit configured to set the system information, the system
information indicating that the user temiinal of the macrocell can access the femtocell.
According to a specific embodiment of the present invention, a BOOLEAN
information indication of csg-indication in information block 1 of the system information is set
to be "FALSE" by the system information setting unit.
According to a specific embodiment of the present invention, there is provided a user
temiinal equipment which is within coverage range of a femtocell. The user temiinal
equipment comprises:
a detecting unit configured to detect whether initiation of a random access request is
allowed; and
a random access request initiating unit configured to initiate the random access request
to the femtocell when the detecting unit outputs information allowing initiation of a random
access request.
According to a specific embodiment of the present invention, the user temiinal
equipment further includes a first receiving unit configured to receive system information from
the femtocell; and the detecting unit detects the system information from the femtocell and
outputs to the random access request initiating unit the information allowing initiation of a
random access request once it detects that the system information from the femtocell indicates
that the user terminal of the macro cell can access the femtocell
According to a specific embodiment of the present invention, the user temiinal
equipment further comprises a closed subscriber group whitelist storage unit configured to
store whitelist of closed subscriber groups; settings of the closed subscriber group whitelist
storage unit is updated to comprise all femtocells that potentially cause interferences to the
user temiinal of the macro cell; and when the detecting unit detects that the whitelist of closed
subscriber groups includes all femtocells that potentially cause interferences to the user
temiinal of the macro cell, it outputs to the random access request initiating unit the
information allowing initiation of a random access request.
According to a specific embodiment of the present invention, the user temiinal
equipment further comprises a second receiving unit configured to receive from a user an
instruction which instructs the user equipment to initiate the random access request to the
femtocell; and when the detecting unit detects the instruction which instructs the user
equipment to initiate the random access request to the femtocell, it outputs to the random
access request initiating unit the information allowing initiation of a random access request.
According to a specific embodiment of the present invention, a BOOLEAN
information indication of csg-indication in information block 1 of the system information of the
femtocell is set to be "FALSE".
According to a specific embodiment of the present invention, the information settings
of the whitelist of closed subscriber groups of the user temiinal of the macrocell is obtained
through information from a network side, or obtained through empirical information of a user
temiinal side, and it is updated through a radio resource control connection.
The other features and advantages of the present invention will become more apparent
after reading the detailed description of the embodiments of the invention in conjunction with
the accompanying drawings.
Brief Description of the Drawings
The accompanying drawings illustrated herein are to provide a further understanding of
the invention and to constitute a part of the application. The schematic embodiments of the
invention and the description thereof are to explain the invention and not to constitute an
unsuitable limitation to the invention. In the accompanying drawings:
FIG. 1 illustrates a macrocell-femtocell deployment scenario in the LTE system.
FIG. illustrates a schematic view of the process of the femtocell interference
coordination according to an embodiment of the present invention.
FIG.3 illustrates a structural schematic view of a femtocell according to an
embodiment of the present invention.
FIG.4 illustrates a structural schematic view of a user terminal equipment according to
an embodiment of the present invention.
Detailed Description of the Invention
Specific embodiments of the present invention will now be explained in detail in
conjunction with the accompanying drawings.
For a scenario in which a user temiinal equipment of macrocell is powered on after
moving into the dead zone, the present invention presents three methods to trigger the user
temiinal equipment of the macrocell to initiate a random access to a femtocell so as to trigger
the femtocell to perform interference coordination processing.
Detailed descriptions are set out hereinafter in conjunction with FIG. 2.
In step S201, the user temiinal equipment of the macrocell is synchronized to the
femtocell after powered on. After that, in step S202, any one of the following three methods
may be used to trigger the user temiinal equipment of the macrocell to initiate a random access
to the femtocell.
1. The femtocell sets parameters in its system information to allow user temiinals of
the macrocell, i.e. unauthorized user equipments, to initiate random access to the femtocell.
By way of a specific example, in the system information of the current 3GPP LTE-A system, a
BOOLEAN information indication of "csg-indication" in the system information block 1(SIB-
1) is used to indicate rules of cell access for user equipments. If the information is set to be
"TRUE", the user can only access a cell of closed subscriber group whose closed subscriber
group ID is consistent with his whitelist of closed subscriber groups. If the information is set
to be "FALSE", there is no limitation to the access. Therefore, when the user equipment of the
macrocell is synchronized to the femtocell, the femtocell sets the csg-indication in the system
information block 1 to be "FALSE", and sends to the user terminal of the macrocell the
system information block 1 with the csg-indication set to be "FALSE". When the user terminal
of the macrocell received the above said information block 1, perform step S203 to initiate the
random access to the femtocell.
2. The default information of "closed subscriber groups" is set to include all femtocells
that may potentially cause interferences to the user equipment of the macrocell.
This method sets information of the "whitelist of closed subscriber groups" for the user
equipment of the macrocell to include all femtocells that may potentially cause interferences to
the user equipment of the macrocell. Since the "whitelist of closed subscriber groups" is
controlled by non-access layers (at network side), it is required to define a new default
"whitelist of closed subscriber groups" to be stored in the user equipment of the macrocell
through non-network layer information. This process may be performed by the network side
or the user equipment side and may be updated through the most recent radio resource control
(RRC) connection. When a cell access is completed by the user equipment of the macrocell,
the default "whitelist of closed subscriber groups" may be updated to more effective
information, such as not including all femtocells that may potentially cause interferences to the
user terminal of the macrocell.
3. Triggering a manual access to the "closed subscriber group".
Using this method, after the user equipment of the macrocell has detected the femtocell,
the user equipment of the macrocell may proceed according to an instruction from the user
which instructs the user equipment of the macrocell to initiate a manual random access request
to the femtocell. This manual random access request is not restricted by the "whitelist of
closed subscriber groups".
In step S203, the user equipment of the macrocell initiates the random access request
to the femtocell, and the femtocell receives the random access request from the user
equipment of the macrocell.
It should be emphasized here that it is not the intention of the various methods above
to let the user equipment of the macrocell actually access the femtocell, but only to trigger the
user equipment of the macrocell to initiate a random access request to the femtocell. It is the
femtocell side that decides whether to permit the user equipment of the macrocell to access
eventually. It is possible that the femtocell does not permit the user equipment of the macrocell
to access. However, the triggering of this random access request may make the femtocell
discover the existence of such a user equipment of the macrocell which is within a dead zone,
and therefore, the following interference coordination operations may be performed.
In step S204, the femtocell estimates path losses, including the path loss from the user
equipment of the macrocell to the femtocell and the path loss from the macrocell to the
femtocell. The femtocell estimates the path loss between the femtocell and the user terminal of
the macrocell based on a default transmitting power value of the user terminal of the macrocell.
In step S205, the femtocell performs the interference coordination. Based on
information of the two path losses obtained by the femtocell at step S204, the existing
enhanced interference coordination algorithms may be adopted by the femtocell, such as
performing interference coordination through power control or time domain resource
allocation.
1. Power Control
The femtocell will perform interference coordination according to reference signal
receiving power and information of path loss.
2. Time Domain Resource Allocation
The femtocell may determine the existence of the dead zone through a coordination
with the macrocell, and arrange the time domain resource allocation to implement the
interference coordination. Based on this, a BOOLEAN information used for confirming the
user equipment of the macrocell should be defined between the femtocell and the macrocell.
FIG.3 illustrates a structural schematic view of a femtocell according to an
embodiment of the present invention. In the embodiment, the femtocell 300 includes a
synchronizing unit 301, a receiving unit 302, a path loss estimating unit 303 and an
interference coordination unit 304.
In particular, the synchronizing unit 301 is configured to receive synchronization
information from user temiinals of the macrocell within the coverage range of the femtocell.
The receiving unit 302 is configured to receive a random access request initiated by a user
temiinal of the macrocell. The path loss estimating unit 303 is configured to estimate the path
loss from the user temiinal of the macrocell to the femtocell. The interference coordination
unit 304 is configured to perform interference coordination to ensure that the user temiinal of
the macrocell may receive information of control channels correctly.
In the path loss estimating unit 303, the femtocell estimates the path loss between the
femtocell and the user terminal of the macrocell based on a default transmitting power value of
the user terminal of the macrocell.
The interference coordination unit 304 performs the interference coordination based on
the path loss between the femtocell and the user terminal of the macrocell and the path loss
between the femtocell and the macrocell estimated by the femtocell. The interference
coordination is achieved through power control or time domain resource allocation described
in step S205. In particular:
1. Power Control
The interference coordination unit 304 performs interference coordination according to
reference signal receiving power and information of path loss.
2. Time Domain Resource Allocation
The femtocell 300 may determine the existence of the dead zone through a
coordination with the macrocell, and the interference coordination unit 304 arranges the time
domain resource allocation to implement the interference coordination. Based on this,
BOOLEAN information used for confirming the user equipment of the macrocell should be
defined between the femtocell and the macrocell.
Furthermore, if the system settings select a mode in which the femtocell sets
parameters in its system information to allow the user temiinal of the macrocell, i.e. an
unauthorized user equipment, to initiate a random access to the femtocell, the femtocell 300
may further include a system information setting unit configured to set the system information,
where the system information indicates that the user temiinal of the macrocell can access the
femtocell. In the system information of the current 3GPP LTE-A system, a BOOLEAN
information indication of "csg-indication" in the system information block l(SIB-l) is used to
indicate rules of cell access for user equipments. If the information is set to be "TRUE", the
user can only access a cell of closed subscriber group whose closed subscriber group ID is
consistent with his whitelist of closed subscriber groups. If the information is set to be
"FALSE", there is no limitation to the access. Therefore, when the user equipment of the
macrocell is synchronized to the femtocell, the femtocell sets the csg-indication in the system
information block 1 to be "FALSE". The femtocell sends to the user terminal of the macrocell
the system information block 1 with the csg-indication set to be "FALSE".
As mentioned above, it is not the intention of the invention to let the user equipment of
the macrocell acturally access the femtocell, but only to trigger the user terminal equipment of
the macrocell to initiate a random access request to the femtocell. It is the femtocell side that
decides whether to permit the user equipment of the macrocell to access. It is possible that the
femtocell does not permit the user equipment of the macrocell to access. However, the
triggering of this random access request may make the femtocell discover the existence of
such a user equipment of the macrocell which is within a dead zone and therefore, the
following interference coordination operations can be performed.
FIG.4 illustrates a structural schematic view of a user terminal equipment according to
an embodiment of the present invention. In the embodiment, the user terminal equipment 400
includes a detecting unit 401, a random access request initiating unit 402, and may further
include any one of a closed subscriber group whitelist storage unit 403, a first receiving unit
404 and a second receiving unit 405 according to various system arrangements.
In particular, the detecting unit 401 is configured to detect whether initiation of a
random access request is allowed.
The random access request initiating unit 402 is configured to initiate the random
access request to the femtocell when the detecting unit outputs an information allowing
initiation of a random access request.
The closed subscriber group whitelist storage unit 403 is configured to store the
"whitelist of closed subscriber groups". The closed subscriber group whitelist storage unit is
set to update information o f the "whitelist of closed subscriber groups" to include all
femtocells that may potentially cause interferences to the user temiinal of the macrocell. When
the detecting unit detects that the "whitelist of closed subscriber groups" includes all
femtocells that may potentially cause interferences to the user terminal of the macrocell, it
outputs to the random access request initiating unit the information allowing initiation of a
random access request. Since the "whitelist of closed subscriber groups" is controlled by nonaccess
layers (at network side), it is required to define a new default "whitelist of closed
subscriber groups" to be stored in the user equipment of the macrocell through non-network
layer information. This process may be performed by the network side or the user equipment
side and may be updated through the most recent radio resource control (R C) connection.
When a cell access is completed by the user equipment of the macrocell, the default "whitelist
of closed subscriber groups" may be updated to more effective information, such as not
including any femtocells that may potentially cause interferences to the user terminal of the
macrocell.
The first receiving unit 404 is configured to receive system information from the
femtocell. The detecting unit 401 detects the system information from the femtocell and
outputs to the random access request initiating unit the information allowing initiation of a
random access request once it detects that the system information from the femtocell indicates
that the user terminal of the macrocell can access the femtocell. As a specific example, a
BOOLEAN information indication of "csg-indication" in the information block 1 of the system
information of the femtocell is set to be "FALSE".
The second receiving unit 405 is configured to receive from a user an instruction which
instructs the user equipment to initiate the random access request to the femtocell. When the
detecting unit 401 detects the instruction which instructs the user equipment to initiate the
random access request to the femtocell, it outputs to the random access request initiating unit
the information allowing initiation of a random access request.
Until now, no solution in the prior arts has directed to the problem of powering on of a
user equipment of the macrocell in a dead zone. In this invention, we have presented an
enhanced inter-cell interference coordination solution for the case in which the user equipment
of the macrocell is powered on in the dead zone. With this method, the femtocell can confirm
the existence of the user equipment of the macrocell and then trigger the power control or
time domain resource allocation solutions to ensure that the user terminal of the macrocell will
receive information of control channels correctly. This enables the user equipment of the
macrocell to communicate with the macrocell smoothly after being powered on in the dead
zone.
The present invention may be implemented in hardware, software, firmware or the
combination thereof. Those skills in this art may appreciate that the present invention may be
embodied in a computer program product arranged on a signal carrying media used by any
suitable data processing systems. The signal carrying media may be transmission media or
recordable media for machine readable information, including magnetic media, optical media
or any other suitable media. Examples of recordable media include magnetic disk or soft disk
in a hard drive, optical disk for optical drive, tape or other media that can be conceived by
those skills in this art. Those skills in this art may appreciate that any communication devices
with suitably programmed means will be able to perform the steps of the invention as
embodied in a program product.
It should be understood from the above description that various embodiments of the
invention can be modified and altered without departing from the sprit of the invention. The
description in this document is only used for illustration but not to be construed as limiting.
The scope of the invention is only limited by the claims.
Claims
What is claimed is:
1. A method for interference coordination by a femtocell, wherein there is at least one
user terminal of a macrocell within coverage range of the femtocell, the method comprising:
1) the femtcell receiving a random access request initiated by the user terminal of the
macrocell;
2) the femtcell estimating path loss between the femtocell and the user terminal of the
macrocell; and
3) the femtcell performing interference coordination to ensure that the user terminal of
the macrocell can receive information of control channels correctly.
2. The method according to claim 1, wherein the femtocell receiving a random access
request initiated by the user terminal of the macrocell further comprises:
1) synchronizing the user terminal of the macrocell to the femtocell;
2) the user terminal of the macrocell receiving system information of the femtocell, the
system information of the femtocell indicating that the user terminal of the macrocell can
access the femtocell; and
3) the user terminal of the macrocell initiating the random access request to the
femtocell.
3. The method according to claim 1, wherein the femtocell receiving a random access
request initiated by the user terminal of the macrocell further comprises:
1) updating information settings of "whitelist of closed subscriber groups" of the user
terminal of the macrocell to comprise all femtocells that potentially cause interferences to the
user terminal of the macrocell;
2) synchronizing the user terminal of the macrocell to the femtocell; and
3) the user terminal of the macrocell initiating the random access request to the
femtocell.
4. The method according to claim 1, wherein the femtocell receiving a random access
request initiated by the user terminal of the macrocell further comprises:
1) synchronizing the user terminal of the macrocell to the femtocell; and
2) the user terminal of the macrocell receiving an instruction from a user to initiate the
random access request to the femtocell.
5. The method according to claim 2, wherein a BOOLEAN information indication of
csg-indication in information block 1 of the system information of the femtocell is set to be
"FALSE".
6. The method according to claim 3, wherein the information settings of "whitelist of
closed subscriber groups" of the user terminal of the macrocell is obtained through
information from a network side, or obtained through empirical information of a user terminal
side, and it is updated through a radio resource control connection.
7. The method according to any one of claims 1-6, wherein the femtocell estimates the
path loss between the femtocell and the user terminal of the macrocell based on a default
transmitting power value of the user terminal of the macrocell.
8. The method according to any one of claims 1-6, wherein the femtocell performs the
interference coordination based on power control or time domain resource allocation.
9. The method according to claim 8, wherein, the femtocell performs the interference
coordination based on the path loss between the femtocell and the user terminal of the
macrocell and the path loss between the femtocell and the macrocell estimated by the femtocell.
10. A method for initiating a random access to a femtocell by a user terminal, wherein
the user terminal is a user terminal of a macrocell and is located in coverage area of the
femtocell, and the user terminal of the macrocell is an unauthorized user terminal for the
femtocell, the method comprising:
1) the user terminal obtaining information allowing initiation of a random access
request to the femtocell; and
2) the user terminal initiating the random access request to the femtocell.
11. The method according to claim 10, wherein the user terminal obtaining information
allowing initiation of a random access request to the femtocell comprises: the user terminal
receiving system information from the femtocell, the system information of the femtocell
indicating that the user terminal of the macrocell can access the femtocell
12. The method according to claim 10, wherein the user terminal obtaining information
allowing initiation of a random access request to the femtocell comprises: information settings
of "whitelist of closed subscriber groups" of the user terminal of the macrocell comprising all
femtocells that potentially cause interferences to the user terminal of the macrocell.
13. The method according to claim 10, wherein the user terminal obtaining information
allowing initiation of a random access request to the femtocell comprises: the user terminal
receiving from a user an instruction which instructs the user equipment to initiate the random
access request to the femtocell.
14. The method according to claim 11, wherein a BOOLEAN information indication of
csg-indication in information block 1 of the system information of the femtocell is set to be
"FALSE".
15. The method according to claim 12, wherein the information settings of "whitelist of
closed subscriber groups" of the user terminal of the macrocell is obtained through
information from a network side, or obtained through empirical information of a user terminal
side, and it is updated through a radio resource control connection.
16. A femtocell, wherein there is at least one user terminal of a macrocell within
coverage range of the femtocell, the femtocell comprising:
a synchronizing unit configured to receive synchronization information from the user
temiinal of the macrocell within the coverage range of the femtocell;
a receiving unit configured to receive a random access request initiated by the user
temiinal of the macrocell;
a path loss estimating unit configured to estimat path loss from the user temiinal of the
macrocell to the femtocell and path loss from the macrocell to the femtocell; and
an interference coordination unit configured to perform interference coordination to
ensure that the user temiinal of the macrocell can receive information of control channels
correctly.
17. The femtocell according to claim 16, wherein the path loss estimating unit
estimates the path loss between the femtocell and the user temiinal of the macrocell based on a
default transmitting power value of the user temiinal of the macrocell.
18. The femtocell according to claims 16 or 17, wherein the interference coordination
unit performs the interference coordination based on power control or time domain resource
allocation.
19. The femtocell according to claim 18, wherein the interference coordination unit
performs the interference coordination based on the path loss between the femtocell and the
user terminal of the macrocell and the path loss between the femtocell and the macrocell
estimated by the femtocell.
20. The femtocell according to claim 16, further comprises a system information
setting unit configured to set the system information, the system information indicating that
the user temiinal of the macrocell can access the femtocell.
21. The femtocell according to claim 20, wherein a BOOLEAN information indication
of csg-indication in information block 1 of the system information is set to be "FALSE" by the
system information setting unit.
22. A user temiinal equipment, which is within coverage range of a femtocell, the user
temiinal equipment comprising:
a detecting unit configured to detect whether initiation of a random access request is
allowed; and
a random access request initiating unit configured to initiate the random access request
to the femtocell when the detecting unit outputs information allowing initiation of a random
access request.
23. The user temiinal equipment according to claim 22, wherein:
the user temiinal equipment further comprises a first receiving unit configured to
receive system information from the femtocell; and
the detecting unit detects the system information from the femtocell and outputs to the
random access request initiating unit the information allowing initiation of a random access
request once it detects that the system information from the femtocell indicates that the user
temiinal of the macrocell can access the femtocell
24. The user temiinal equipment according to claim 22, wherein:
the user temiinal equipment further comprises a closed subscriber group whitelist
storage unit configured to store whitelist of closed subscriber groups; and
settings of the closed subscriber group whitelist storage unit is updated to comprise all
femtocells that potentially cause interferences to the user temiinal of the macrocell; and
when the detecting unit detects that the whitelist of closed subscriber groups includes
all femtocells that potentially cause interferences to the user temiinal of the macrocell, it
outputs to the random access request initiating unit the information allowing initiation of a
random access request.
25. The user terminal equipment according to claim 22, wherein:
the user terminal equipment further comprises a second receiving unit configured to
receive from a user an instruction which instructs the user equipment to initiate the random
access request to the femtocell; and
when the detecting unit detects the instruction which instructs the user equipment to
initiate the random access request to the femtocell, it outputs to the random access request
initiating unit the information allowing initiation of a random access request.
26. The user temiinal equipment according to claim 23, wherein a BOOLEAN
information indication of csg-indication in information block 1 of the system information of the
femtocell is set to be "FALSE".
27. The user temiinal equipment according to claim 24, wherein the information
settings of the whitelist of closed subscriber groups of the user temiinal of the macrocell is
obtained through information from a network side, or obtained through empirical information
of a user temiinal side, and it is updated through a radio resource control connection.