KR101641737B1 - Method for changing assignment of carrier frequence band or segment and for managing tx power of the femto ap - Google Patents

Abstract

A method for selectively changing a carrier frequency band or a segment allocation change method used by a femto base station and a transmit power of a femto base station is disclosed herein. According to one embodiment, the femto base station determines whether there is a need to change the carrier frequency band or segment allocation based on the magnitude of the signal-related data and the controlled transmit power, and the need to change the carrier frequency band or segment allocation The femto base station may transmit a carrier frequency band or a segment allocation change request message to the ACS.

PUSC, carrier frequency, Tx power, transmit power, WiMax

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of allocating a carrier frequency band or a segment, and a method of managing transmit power of a femto base station,

The present invention relates to a femto base station, and more particularly, to a method for changing allocation of a carrier frequency band or a segment used by a femto base station and a method for selectively managing transmission power of a femto base station.

In recent years, due to the rapid development of communication, computer network and semiconductor technology, not only various services using wireless communication networks have been provided, but also the demands of users have been increasing day by day, and the worldwide mobile communication technology has been increasing explosively to be. With the development of mobile communication, users' usage patterns and demands are also diversified, and they want to communicate without restriction of time and space. In accordance with this demand, a femto-type base station is installed to compensate for the quality of mobile communication service by installing it in an area where a radio wave of a macro cell deteriorates, such as a home or a building, or in a shaded area.

Such a femto base station should provide mobile communication services by minimizing signal interference among a plurality of users. Hereinafter, an operation of a wireless communication system in which a conventional femto base station is utilized will be briefly described. After booting, the femto base station receives configuration information from an ACS (Auto Configuration Server) responsible for configuration information and status management of the femto base station, and applies the configuration information to the femto base station. At this time, the femto base station receives configuration information from the ACS and provides services to users' terminals at a predetermined transmission power (Tx Power), and periodically transmits uplink / downlink signals for terminals measured at the femto base station The transmit power is dynamically adjusted using measurement data (e.g., including CINR values). The terminal may measure the signal and transmit the data to the corresponding femto base station of the jurisdiction. The femto base station informs the ACS of the adjusted transmission power so that information about the femto base station can be managed consistently.

However, if the transmission power of such a femto base station is maintained at a predetermined maximum value while exceeding a certain threshold value capable of interfering with other terminals, it will adversely affect services of other users.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a femto base station in which a transmission power is maintained at a predetermined maximum value while exceeding a predetermined threshold that can cause interference to other terminals, Or selectively controlling the transmission power of the neighboring femto base stations to minimize the interference of signals to the user.

According to an embodiment of the present invention, a method of allocating a carrier frequency band or segment is provided. A wireless communication system comprising at least one terminal, at least one femto base station over the at least one terminal, and an ACS (Auto Configuration Server) communicating with the at least one femto base station, the at least one femto base station Uses a first one of a plurality of carrier frequency bands available for communication with the at least one terminal, each of the plurality of carrier frequency bands includes a plurality of segments, and the at least one femto base station Wherein at least one of the at least one femto base station uses a segment of the first carrier frequency band or only a specific segment to communicate with the at least one terminal, The carrier frequency band or segment How to change the assignment includes the steps of said any one of a femto base station type provided with at least one terminal and a signal-related data measurements and periodically measures the signal-specific data that is used for communication; The femto base station controlling the magnitude of the transmission power to the at least one terminal based on the signal related data measurement value; Determining whether any one of the femto base stations needs to change a carrier frequency band or a segment to be communicated with the at least one terminal based on the signal related data and the size of the controlled transmission power; And a step in which the femto base station transmits a carrier frequency band change request message or a segment allocation change request message to the ACS when it is determined that there is a need to change the carrier frequency band or the segment allocation in the determining step can do.

In one embodiment, the signal related data may include Carrier to Interference and Noise Ratio (CINR) values.

In one embodiment, the determining comprises: determining whether the signal related data measurements exceed a predetermined threshold; Counting the number of times that the magnitude of the controlled transmission power corresponds to a predetermined maximum transmission power when it is determined that the signal related data measurement value exceeds a predetermined threshold value; Determining whether the counted number is greater than or equal to a predetermined number; And determining that there is a need to change the carrier frequency band or the segment if the counted number is determined to be equal to or greater than a predetermined number of times.

In one embodiment, the step of the femto base station transmitting the carrier frequency band or the segment allocation change request message to the ACS may include determining whether any one of the femto base stations uses a specific segment or all segments ; If the femto BS determines to use a specific segment, the femto BS transmits a segment allocation change request message to the ACS; And transmitting the carrier frequency band allocation change request message to the ACS when the femto base station determines that all of the segments are used by the femto base station.

In one embodiment, the method for allocating the carrier frequency band or the segment may include a step in which the one femto base station instructs the one of the femto base stations to allocate the carrier frequency band or the segment from the ACS Receiving a carrier frequency band or segment allocation change response message; And changing a carrier frequency band or a segment used by the one femto base station to communicate with the at least one terminal based on the carrier frequency band or the segment allocation change response message .

In one embodiment, the method for allocating the carrier frequency band or segment to any one of the femto base stations is determined by a radio resource allocation change determination performed by the ACS, and the radio resource allocation change determination is performed by the ACS The femtocell base stations other than the femtocell base stations communicating with the ACS all of the plurality of carrier frequency bands available for use by the one femto base station Judging whether or not it is used; In response to a determination that all of the plurality of usable carrier frequency bands are used in a femto base station other than the one of the femto base stations communicating with the ACS, a carrier having the smallest frequency among the plurality of carrier frequency bands Determining a frequency as a carrier frequency to be used by any one of the femto base stations; And in response to a determination that all of the plurality of available carrier frequency bands are not used by a femto base station other than the one of the femto base stations communicating with the ACS, And the frequency band is determined as a carrier frequency band to be used by any one of the femto base stations.

In one embodiment, the radio resource allocation change determination may include: counting the number of times the ACS receives the segment allocation change request message when receiving the segment allocation change request message; Following the procedure when the ACS receives the carrier frequency band allocation change request message if the counted number is greater than or equal to a predetermined number of times; Determining whether all of a plurality of segments usable by the one femto base station are being used by another femto base station communicating with the ACS if the counted number is less than a predetermined number of times; Determining a segment of the unused segment as a segment to be used by any one of the femto BSs if the other femto BS communicating with the ACS determines that there is a segment that is not currently used; If it is determined that the other femto BS communicating with the ACS is currently using all the segments, determining that the segment having the smallest frequency among the plurality of segments is a segment to be used by any one of the femto BSs .

According to an embodiment of the present invention, a method of managing transmit power of a femto base station can be provided. A wireless communication system comprising at least one terminal, at least one femto base station over the at least one terminal, and an ACS in communication with the at least one femto base station, the at least one femto base station comprising: Using at least one of a plurality of carrier frequency bands available for communicating with the terminal, wherein the at least one femto base station also uses all segments of the first carrier frequency band to communicate with the at least one terminal Or only a specific segment of the at least one femto base station, the method of managing the transmit power of the at least one femto base station comprises the steps of: using a signal used by the first femto base station of the at least one femto base station to communicate with the at least one terminal The related data is periodically measured and the signal related data side Providing a value; The first femto base station controlling a magnitude of transmit power to the at least one terminal based on the signal related data measurement; Determining whether there is a need to change a carrier frequency band or a segment in which the first femto base station communicates with the terminal based on the signal related data and the size of the controlled transmission power; Transmitting a carrier frequency band or a segment allocation change request message to the ACS when the first femto base station determines that there is a need to change the carrier frequency band or the segment allocation in the determining step; And a femto base station that uses the maximum transmission power of the at least one femto base station in response to the ACS receiving the carrier frequency band or the segment allocation change request message, As shown in FIG.

In one embodiment, the at least one femto base station transmits its location information to the ACS, wherein the selecting is performed based on at least one of the location information and the signal related data .

In one embodiment, the at least one femto base station may further comprise receiving location information of the at least one mobile terminal from the at least one mobile terminal and transmitting the location information to the ACS, Can be selected based on at least one of the position information of the at least one femto base station, the position information of the at least one mobile terminal and the signal related data.

According to an embodiment of the present invention, it is possible to reduce interference with other terminals in a service area of a specific femto base station through a carrier frequency band allocation change or a segment allocation change. In addition, according to another embodiment of the present invention, it is possible to reduce interference between femto base stations through transmission power control of other femto base stations adjacent to a specific femto base station.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

1 is a configuration diagram of an exemplary communication network environment 100 in which the present invention may be practiced. 1, the communication network environment 100 includes femto base stations 110a and 110b (referred to as 110 when referring to general information about a femto base station) and an ACS (Auto Configuration Server) 120 . The femto base stations 110a and 110b may provide a communication service to the terminal. 1, the communication network environment 100 includes two femto base stations 110a and 110b and one ACS 130, but this helps to illustrate the actual number and arrangement of base stations and terminals. It should be noted that it may be different.

The communication network environment 100 may be implemented in a wireless communication system such as, for example, Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications (GSM), Universal Mobile Telecommunications System (UMTS), Worldwide Interoperability for Microwave Access ), HSDPA (High Speed Downlink Packet Access), LTE (Long Term Evolution), 2G, 3G, 3.5G and 4G which will be developed in the future including conventional mobile communication network and next generation mobile communication network, have.

In one embodiment of the present invention, the femto base station 110 determines based on the measurement data for the uplink / downlink signals that its transmit power is maintained at a maximum value that can cause interference to other terminals, The ACS 120 may transmit a carrier frequency band or a segment allocation change request message to the ACS 120. The ACS 120 may determine the carrier frequency band or the segment allocation change request, ) To change the carrier frequency band or segment allocation. In one embodiment, the ACS 120 may respond to turn off the power of a particular femto base station or to lower transmit power in response to a request to change the carrier frequency band or segment allocation.

The femto base station can communicate with a terminal using a specific carrier frequency band among a plurality of available carrier frequency bands. In addition, the femto base station physically divides radio resources into several segments (one segment is a kind of radio resource division unit consisting of several subchannels) within a frequency band having a specific carrier frequency band, (PUSC), or all frequency bands (i.e., all segments) of a specific carrier frequency, to communicate with the terminal Assignment). Hereinafter, the femto base station will be referred to as "communicating using a specific segment" when the femto base station communicates with a terminal using only a specific one of the carrier frequency bands, Quot; all segments are used for communication "when communicating with a terminal using a frequency band (i.e., all segments).

In the present invention, "changing the carrier frequency band allocation" means that a specific carrier frequency band used by the femto base station in communication with the terminal is changed to any one of a plurality of available carrier frequency bands In the present invention, the "segment allocation change" means that the femto base station changes its allocation to any one of a plurality of segments that can be used in a frequency band having a specific carrier frequency band when communicating with the terminal As those skilled in the art will appreciate, the detailed description is omitted here.

In an exemplary embodiment of the present invention, a carrier frequency band is allocated to a specific femto base station to reduce interference using a carrier frequency band different from that of a neighboring femto base station. In another embodiment of the present invention, The specific femto base station can reduce the interference by using the segments in the specific carrier frequency band different from the neighboring femto base stations.

2 is a configuration diagram of a femto base station 110 and an ACS 120 according to an embodiment of the present invention. It should be noted that the components shown in FIG. 2 are illustrative, and that components may be integrated, separated, or omitted according to design specifications, and the connection relationship of each component may be changed.

As shown in FIG. 2, the femto base station 110 may include a communication unit 111 capable of transmitting and receiving data to and from the ACS 120. The communication unit 111 may receive various information from the ACS 120 or may transmit a carrier frequency band or a segment allocation change request message to the ACS 120. [

As shown in FIG. 2, the femto base station 110 may further include a signal data measurement unit 112. The signal data measurement unit 112 may periodically measure data related to the uplink and downlink signals used for communication with the terminal. In one embodiment, the signal data measurement unit 112 may receive data related to the uplink and downlink signals from a terminal in the jurisdiction of the femto base station 110. For example, the above data may include Carrier to Interference and Noise Ratio (CINR) values. Data related to the signal obtained by the signal data measurement unit 112 can be transmitted to the ACS 120 through the communication unit 111. [

As shown in FIG. 2, the femto base station 110 may further include a transmission power controller 113. The transmission power controller 113 can control the transmission power (Tx power) used when the femto base station 110 communicates with a terminal in a jurisdiction. In one embodiment, if the transmission power controller 113 determines that there are a plurality of intra-signal interference, the transmission power can be increased. The transmission power control section 113 can control the transmission power level based on the data measured by the signal data measurement section 112. In one embodiment, the transmission power control section 113 can predefine a range that can be controlled. In one embodiment, the transmission power controller 113 may set the transmission power to a maximum value when there is intra-signal interference exceeding a predetermined threshold in the data measured by the signal data measurement unit 112. [

As shown in FIG. 2, the femto base station 110 may further include an allocation change determination unit 114. The allocation change determination unit 114 can determine whether the femto base station 110 should change the carrier frequency band of the signal communicating with the terminal in its jurisdiction. In one embodiment, the allocation change determination unit 114 may determine whether or not the femto base station 110 should allocate and change a segment of a signal communicating with a terminal in its jurisdiction.

In one embodiment, the allocation change determination unit 114 may check whether the data periodically measured by the signal data measurement unit 112 is out of a predetermined threshold. Here, "out of the threshold value" may mean a criterion that determines that the signal starts to receive interference. For example, when the CINR falls below a predetermined threshold value, it can be determined that the interference received by the signal exceeds a predetermined allowable value.

If the above data is out of a predetermined threshold, it is checked whether the magnitude of the transmission power dynamically controlled by the transmission power controller 113 corresponds to the predetermined maximum transmission power, and if it corresponds to the maximum transmission power, the count is incremented by one . In one embodiment, the count may be incremented by one until the determination that it corresponds to the maximum transmit power is continuously maintained, and in another embodiment, the discontinuity may be incremented by one.

When the sum of the counts becomes n, the allocation change determination unit 114 can determine whether the femto base station 110 is using a specific segment or all the segments to communicate with the terminal. Here, n is a natural number of 2 or more, and in one embodiment of the present invention, n is 4. If only one specific segment is used, the allocation change determination unit 114 can transmit a segment allocation change request message to the ACS 120 via the communication unit 111. [ If all segments are used, the allocation change determination unit 114 may transmit a carrier frequency band allocation change request message to the ACS 120 via the communication unit 111. [

As shown in FIG. 2, the femto base station 110 may further include a position determination unit 115. In an embodiment of the present invention, the position determination unit 115 may include a femto base station position determination unit and / or a terminal position determination unit.

In one embodiment of the present invention, the femto base station position determination unit may obtain position information of the femto base station 110. [ The femto base station position determination unit can obtain position information of the femto base station 110 by using Global Positioning System (GPS) technology, obtain its position by using a position acquisition technique known in the other industries, The detailed description will be omitted. In an embodiment of the present invention, the terminal position determination unit may obtain position information of the terminal by receiving position information on the terminal from a terminal in the jurisdiction of the femto base station 110. The UE may periodically transmit its position information to the terminal position determination unit of the femto base station 110. [

In one embodiment, the location determination unit 115 may determine location information of the femto base station 110 and / or the jurisdictions obtained from the femto base station location determination unit and / or the terminal location determination unit to the communication unit 111 Lt; RTI ID = 0.0 > ACS 120 < / RTI > In one embodiment, the femto base station 110 may transmit location information to the ACS 120 when it is booted.

As shown in FIG. 2, the ACS 120 may include a communication unit 121 capable of transmitting and receiving data with the femto base station 110. The communication unit 121 may receive a carrier frequency band or a segment allocation change request message from the femto base station 110 or may transmit a carrier frequency band or a segment allocation message to the femto base station 110.

As shown in FIG. 2, the ACS 120 may further include a radio resource allocation changing unit 122. The radio resource allocation changing unit 122 may change a carrier frequency band or a segment according to a carrier frequency band allocation change request or a segment allocation change request of the femto base station 110. In one embodiment, the radio resource allocation changing unit 122 may include a carrier frequency band allocation changing unit 122a and a segment allocation changing unit 122b.

The radio resource allocation changing unit 122 may receive the carrier frequency band allocation change request message or the segment allocation change request message from the allocation change determination unit 114 of the femto base station 110 through the communication unit 121. [ When the radio resource allocation changing unit 122 receives the segment allocation change request message, it can store the number of reception times. The carrier frequency band allocation changing unit 122a operates when the radio resource allocation changing unit 122 receives the segment allocation change request message from the same femto base station 110 m times or more, (122b) can be operated. M is a natural number greater than or equal to 2, and n is 2 in one embodiment of the present invention. When the radio resource allocation changing unit 122 receives the carrier frequency band allocation change request message, the carrier frequency band allocation changing unit 122a may operate.

In one embodiment, if there is a segment that the femto base station 110 does not currently use, the segment allocation change unit 122b may apply the segment to the signal between the femto base station 110 and the terminal of the current jurisdiction. If there is no segment that the femto base station 110 does not currently use, the segment with the least frequency of use may be applied to the signal between the femto base station 110 and the terminal of the current jurisdiction. The segment allocation change unit 122b may transmit the selected segment allocation response to the femto base station 110 through the communication unit 121. [

In one embodiment, the carrier frequency band allocation change section 122a randomly selects an unused carrier frequency band in a plurality of available carrier frequencies (i.e., the entire frequency band pool managed by the ACS 120) And can be used for communication between the base station 110 and a terminal of a current jurisdiction. If all of the available carrier frequency bands are used, a carrier frequency band with less frequency of use can be used for communication between the femto base station 110 and a terminal of the current jurisdiction. The carrier frequency band allocation change unit 122a may transmit the carrier frequency band allocation response to the femto base station 110 through the communication unit 121. [

As shown in FIG. 2, the ACS 120 may further include a femto base station location database 124. The femto base station location database 124 may store the location of the femto base stations and the location information of the terminals received from the location determination unit 115 of the femto base station 110.

As shown in FIG. 2, the ACS 120 may further include a femto base station control unit 123. In one embodiment, when the ACS 120 receives a carrier frequency band or a segment allocation change request through the communication unit 121, the femto base station control unit 123 determines whether a femto base station A femto base station that uses the maximum transmission power, and a femto base station that turns off or decreases the transmission power based on data and / or data on signals received from the signal data measurement unit 112 of the plurality of femto base stations 110 A base station can be selected. In one embodiment of the present invention, a femto base station located close to a mobile terminal can be selected as a femto base station that uses maximum transmit power, and a femto base station located relatively far away can be turned off And can be selected as a femto base station. In another embodiment of the present invention, a femto base station having a relatively good communication state is selected to use the maximum transmission power based on data on signals received from a plurality of femto base stations, The transmission power of the femto base station can be selected to be turned off or decreased. That is, the femto base station control unit 123 can reduce the transmission power of the femto base station, which is determined to generate the interference, to such a degree that interference does not occur. In another embodiment of the present invention, the femto base station control unit 124 checks the relative location information of the femto base stations and the area where they overlap the cell coverage based on the average transmission power, The magnitude of the power can be reduced.

In order to explain the operation of the femto type base station control unit 123 more specifically and intuitively, two femto type base stations 110a and 110b communicating with the ACS 120 for convenience, and two femto type base stations 110a and 110b, It is assumed that the terminal is located closer to the femto base station 110a than the femto base station 110b and that the terminal can communicate with the femto base station 110a more smoothly. The femto base station 110a may send a carrier frequency band or segment allocation change request to the ACS 120 (because of increased signal interference due to the femto base station 110b). In response, the femto base station control unit 123 controls the femto base stations 110a and 110b based on the location information of the femto base stations 110a and 110b, the location information of the terminals, and the data (i.e., Interference can be significantly reduced in the communication between the femto base station 110a and the terminal by lowering the transmission power of the femto base station 110b or turning off the transmission power based on the measured value of the interference. It can be judged that there is no hindrance to the communication service to the user. Accordingly, the femto base station control unit 123 can increase the transmission power of the femto base station 110a or change the maximum value thereof, reduce the transmission power of the femto base station 110a, or turn off the power.

3 is a flowchart illustrating in detail a procedure for transmitting a carrier frequency band or a segment allocation change request message in the femto base station 110 according to an exemplary embodiment of the present invention. FIG. 5 is a flowchart illustrating a procedure for allocating a carrier frequency band or a segment in the ACS 120 according to an exemplary embodiment of the present invention. Referring to FIG. 5, And the femto base station is not used. It should be noted that the steps shown in Figs. 3 to 5 are illustrative, and that the steps can be combined, separated or omitted, and that the order of the steps can be changed.

FIG. 3 shows a procedure for transmitting a carrier frequency band or a segment allocation change request message from the femto base station 110 to the ACS 120. First, the femto base station 110 periodically measures data (e.g., CINR) related to the uplink and downlink signals used in communication with the UE (step 300). The femto base station 110 can dynamically control the size of the transmission power according to the measured signal value (step 302). At this time, it may be determined whether the signal measurement value is out of a predetermined threshold (step 304). If the signal measurement value does not exceed the predetermined threshold, the process may return to step 300 (step 306).

If the signal measurement value exceeds a predetermined threshold, it may be determined whether the magnitude of the controlled transmit power corresponds to a predetermined maximum transmit power (step 308). If it does not correspond to the maximum transmit power, it may return to step 300 (step 310). When the maximum transmission power is met, the number of times set as the maximum transmission power is counted, and it can be determined whether or not the counted number is n times or more (step 312). If it is less than n times, it may return to step 300 (step 314). If it is n times or more, it can be determined whether the corresponding femto base station uses all the segments or uses a specific segment to communicate with the terminal (step 316). If it determines that it is using a particular segment, it may send a segment allocation change request message to the ACS 120 (step 318). If it is determined that all segments are used, the ACS 120 may transmit a carrier frequency band allocation change request message (step 320).

4 shows a procedure for allocating a carrier frequency band or a segment in the ACS 120 and transmitting an allocation change response message to the femto base station 110. FIG. First, a radio resource allocation change request may be received from the femto base station 110 (step 400). If the received radio resource allocation change request is a segment allocation change request message, the reception count is calculated. If the received segment allocation change request message is received n times or more, the flow proceeds to step 412 (step 402). If the segment allocation change request message is received less than n times, the femto base station 110 may determine whether there is a currently unused segment within the frequency band allocated to the femto base station (step 404). If there is a segment that is not currently used, it may be randomly selected among the unused segments and applied to the signal between the femto base station 110 and the terminal of the current jurisdiction (step 406). If there is no segment that is not currently used within the frequency band allocated by the femto base station 110, the segment with the lowest frequency of use may be applied to the signal between the femto base station 110 and the terminal of the current jurisdiction 408). Then, the ACS 120 may transmit the segment allocation change response message including the segment information selected in step 406 or 408 to the femto base station 110 (step 410).

When the message received from the femto base station 110 is a carrier frequency band allocation change request message, it can be determined whether all the carrier frequencies belonging to the entire carrier frequency band pool managed by the ACS 120 are used 412). If all available carrier frequencies (that is, registered in the carrier frequency band pool) are used, it can be determined that the carrier frequency band with a low frequency of use is used for communication between the femto base station 110 and a terminal of the current jurisdiction (Step 414). If there is an unused carrier frequency band among the available carrier frequency bands, it is determined that one of the unused carrier frequency bands is randomly used for communication with the terminal of the femto base station 110 (Step 416). Thereafter, the ACS 120 may send a carrier frequency band assignment change response message including information at step 414 or step 416 to the femto base station 110 (step 418).

5 shows a procedure for selecting a femto base station to use the maximum transmission power in the ACS 120 and reducing or turning off the transmission power of the other femto base stations. First, the ACS 120 determines the location of the femto base stations and / or the location information of the terminals of the femto base station and / or the data of the signals received from the femto base stations (i.e., Value) from the femto base station (step 500). At this time, the location information of the terminal of the femto base station can be periodically received from the femto base station. The ACS 120 may then receive a radio resource allocation change request message from the femto base station (step 502). The ACS 120 may then determine, based on the location of the femto base stations and / or the location information of the terminal of the femto base station jurisdiction and / or data (i. E. , A femto base station to use the maximum transmission power, and a femto base station to turn off or reduce the transmission power may be selected (step 504). The ACS 120 may then transmit a response message containing this information to each femto base station (step 506).

Although the above-described methods are described through specific embodiments, the methods described above may also be implemented as computer-readable code on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and may be implemented in the form of a carrier wave (for example, transmission over the Internet) . In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes can be stored and executed in a distributed manner. And, functional programs, codes, and code segments for implementing the above-described embodiments can be easily inferred by programmers of the art to which the present invention belongs.

While the present invention has been described in connection with certain embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention . It is also contemplated that such variations and modifications are within the scope of the claims appended hereto.

1 is a configuration diagram of an exemplary communication network environment 100 in which the present invention may be practiced.

2 is a configuration diagram of a femto base station 110 and an ACS 120 according to an embodiment of the present invention.

FIG. 3 is a flowchart illustrating in detail a procedure for transmitting a carrier frequency band or a segment allocation change request message in a femto base station according to an exemplary embodiment of the present invention. Referring to FIG.

4 is a flow chart detailing a procedure for allocating and changing a carrier frequency band or segment in an ACS according to an embodiment of the present invention;

5 is a flowchart illustrating a procedure for selecting a femto base station to use maximum transmission power in an ACS according to an embodiment of the present invention and not using a femto base station other than the femto base station.

Claims (10)

A wireless communication system comprising at least one terminal, at least one femto base station over the at least one terminal, and an ACS (Auto Configuration Server) communicating with the at least one femto base station, the at least one femto base station Uses a first one of a plurality of carrier frequency bands available for communication with the at least one terminal, each of the plurality of carrier frequency bands includes a plurality of segments, and the at least one femto base station Wherein at least one of the at least one femto base station uses a segment of the first carrier frequency band or only a specific segment to communicate with the at least one terminal, Communicating carrier frequency bands or segments A method of changing sugar, Periodically measuring signal related data used by the one femto base station to communicate with the at least one terminal to provide signal related data measurement values; The femto base station controlling the magnitude of the transmission power to the at least one terminal based on the signal related data measurement value; Determining whether any one of the femto base stations needs to change a carrier frequency band or a segment to be communicated with the at least one terminal based on the signal related data and the size of the controlled transmission power; And If it is determined in the determining step that there is a need to change the carrier frequency band or the segment, the femto base station transmits the carrier frequency band change request message or the segment allocation change request message to the ACS , Way. The method according to claim 1, Wherein the signal related data comprises Carrier to Interference and Noise Ratio (CINR) values. The method according to claim 1, Wherein the determining step comprises: Determining whether the signal related data measurement value exceeds a predetermined threshold; Counting the number of times that the magnitude of the controlled transmission power corresponds to a predetermined maximum transmission power when it is determined that the signal related data measurement value exceeds a predetermined threshold value; Determining whether the counted number is greater than or equal to a predetermined number; And Determining that there is a need to change the carrier frequency band or segment allocation if the counted number is determined to be greater than a predetermined number of times. The method according to claim 1, The step of the femto base station transmitting the carrier frequency band or the segment allocation change request message to the ACS, Determining whether any one of the femto base stations uses a specific segment or all segments; If the femto BS determines to use a specific segment, the femto BS transmits a segment allocation change request message to the ACS; And And if any one of the femto base stations determines to use all segments, transmitting the carrier frequency band allocation change request message to the ACS by any one of the femto base stations. 5. The method of claim 4, Receiving, by the femto base station, a carrier frequency band or a segment allocation change response message indicating a method of allocating the carrier frequency band or the segment from the ACS to the femto base station; And And allocating a carrier frequency band or a segment to be used when the one femto base station communicates with the at least one terminal based on the carrier frequency band or the segment allocation change response message. 6. The method of claim 5, Wherein the method for allocating or changing the carrier frequency band or the segment by the femto base station is determined by a radio resource allocation change determination performed by the ACS, The radio resource allocation change determination When the ACS receives the carrier frequency band allocation change request message, all of the plurality of carrier frequency bands available for the one femto base station communicate with the ACS, Determining whether the base station is used; In response to a determination that all of the plurality of usable carrier frequency bands are used in a femto base station other than the one of the femto base stations communicating with the ACS, a carrier having the smallest frequency among the plurality of carrier frequency bands Determining a frequency as a carrier frequency to be used by any one of the femto base stations; And In response to a determination that all of the plurality of usable carrier frequency bands are not used in a femto base station other than the one of the femto base stations communicating with the ACS, Band is determined as a carrier frequency band to be used by any one of the femto base stations / RTI > The method according to claim 6, Wherein the radio resource allocation change determination includes: Counting the number of times the ACS receives the segment allocation change request message when receiving the segment allocation change request message; Following the procedure when the ACS receives the carrier frequency band allocation change request message if the counted number is greater than or equal to a predetermined number of times; Determining whether all of a plurality of segments usable by the one femto base station are being used by another femto base station communicating with the ACS if the counted number is less than a predetermined number of times; Determining a segment of the unused segment as a segment to be used by any one of the femto BSs if the other femto BS communicating with the ACS determines that there is a segment that is not currently used; If it is determined that the other femto BS communicating with the ACS is currently using all the segments, determining that the segment having the smallest frequency among the plurality of segments is a segment to be used by any one of the femto BSs ≪ / RTI > A wireless communication system comprising at least one terminal, at least one femto base station over the at least one terminal, and an ACS in communication with the at least one femto base station, the at least one femto base station comprising: Using at least one of a plurality of carrier frequency bands available for communicating with the terminal, wherein the at least one femto base station also uses all segments of the first carrier frequency band to communicate with the at least one terminal Or using only a specific segment, comprising the steps of: Periodically measuring signal related data used by a first one of the at least one femto base stations to communicate with the at least one terminal to provide signal related data measurements; The first femto base station controlling a magnitude of transmit power to the at least one terminal based on the signal related data measurement; Determining whether there is a need to change a carrier frequency band or a segment in which the first femto base station communicates with the terminal based on the signal related data and the size of the controlled transmission power; Transmitting a carrier frequency band or a segment allocation change request message to the ACS when the first femto base station determines that there is a need to change the carrier frequency band or the segment allocation in the determining step; And In response to the ACS receiving the carrier frequency band or the segment allocation change request message, a femto base station that uses the maximum transmission power of the at least one femto base station and a femto base station that turns off or reduce transmission power Wherein the method comprises the steps of: 9. The method of claim 8, The at least one femto base station transmitting its location information to the ACS, Wherein the selecting is based on at least one of the location information and the signal related data. 10. The method of claim 9, Wherein the at least one femto base station further comprises receiving location information of the at least one mobile terminal from the at least one mobile terminal and transmitting the location information to the ACS, Wherein the selecting is based on at least one of location information of the at least one femto base station, location information of the at least one mobile terminal, and the signal related data.

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