KR20090115030A - Apparatus and method for femto base station discriminateing in wireless communication system - Google Patents

Abstract

PURPOSE: A femto base station identifying apparatus and a method thereof in a wireless communication system for reducing the complexity and the delay are provided to minimize th e deterioration of synchronization performance by identifying the femto base stations with PCID. CONSTITUTION: A PCID(Physical Cell Identity) of a femto base station is confirmed in case the femto base station is searched(301). An SFN(System Frame Number) of the base station is confirmed as the femto base station(303). The system frame number of the base station is compared as the femto base station. The offset of the femto base station is set up. The femto base station is identified according to the offset(309).

Description

Apparatus and method for distinguishing femto base station in wireless communication system {APPARATUS AND METHOD FOR FEMTO BASE STATION DISCRIMINATEING IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to an apparatus and method for distinguishing a femto base station in a wireless communication system, and in particular, an offset according to a system frame number (hereinafter referred to as SFN) of a macro base station and a femto base station in the wireless communication system. An apparatus and method for distinguishing a femto base station by using the same.

In a cellular wireless communication system, when a channel condition becomes poor due to geographical requirements within a cell or a distance between a terminal and a base station or a movement of the terminal, communication between the terminal and the base station may not be performed smoothly. For example, when the terminal is located in an enclosed building such as an office and a house, a radio wave shadow area is formed in the service area of the base station. Therefore, the base station cannot perform smooth communication with the terminal located in the radio wave shadow area.

Accordingly, the wireless communication system provides a femto-cell service for providing high-speed data services while solving service problems in the radio shadow area. The femto cell refers to a small cell area compared to a macro cell formed by a femto base station installed in a desired region of a user.

A plurality of femto cells may be installed in one macro cell area. In this case, the macro base station managing the macro cell allocates one physical layer cell identifier (PCID) to each femto base station located in its service area. However, since the number of PCIDs that can be allocated from the macro base station to the femto base stations is limited, when there are more femto base stations than the PCID that the macro base station can allocate to the femto base stations, the macro base station is assigned to the femto base stations. Duplicate PCID

As described above, femto cells installed in the macro cell area may have the same PCID. In this case, a problem arises in that the terminal cannot distinguish femto base stations having the same PCID.

Accordingly, an object of the present invention is to provide an apparatus and method for distinguishing a femto base station in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for distinguishing a femto base station using an offset according to a system frame number of a femto base station and a macro base station in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for configuring a global cell identifier of a femto base station in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for recovering a global cell identifier of a femto base station using an offset of a system frame number provided from a terminal in a macro base station of a wireless communication system.

Another object of the present invention is to provide an apparatus and method for setting a system frame number for distinguishing a femto base station in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for adjusting a transmission mode in a femto base station of a wireless communication system.

According to a first aspect of the present invention for achieving the objects of the present invention, a method for distinguishing a femto base station in a terminal of a wireless communication system, when a femto base station is discovered, a physical layer cell identifier (Physical Cell) of the femto base station IDENTITY), a process of checking a system frame number of the femto base station and the macro base station, and comparing the system frame numbers of the femto base station and the macro base station to set the offset of the femto base station And identifying a femto base station according to the offset among at least one femto base station assigned the same physical layer cell identifier as the femto base station.

According to a second aspect of the present invention, an apparatus for distinguishing a femto base station in a wireless communication system includes a receiving unit receiving signals from a femto base station and a macro base station, and when the femto base station is searched through the receiving unit, The physical layer cell identifier (Physical Cell IDentity) and the femto base station and the macro base station is configured to include a control unit for distinguishing the femto base station in consideration of the offset according to the system frame number (System Frame Number).

According to a third aspect of the present invention, when a transmission mode control method is performed in a femto base station of a wireless communication system (TX on), it is determined whether a response signal for a signal transmitted to at least one terminal is received. And a step of periodically transmitting a broadcast signal when the response signal is not received, and stopping the transmission mode (TX off) when a first mode switch message is received from the macro base station. It is characterized by.

According to a fourth aspect of the present invention, a femto base station apparatus of a wireless communication system includes a transmitter for transmitting a transmission signal to at least one terminal, a receiver for receiving a response signal for the transmission signal, and the response signal is received. If not, it characterized in that it comprises a control unit for controlling to transmit the broadcast signal periodically.

According to a fifth aspect of the present invention, a method for generating an identifier of a femto base station in a wireless communication system includes: identifying an identifier of a macro base station to which the femto base station is connected; and a system frame number of the femto base station and the macro base station; Comparing the (System Frame Number) and setting an offset of the femto base station, and generating an identifier of the femto base station by using a predetermined portion of the identifier of the macro base station and the offset.

According to a sixth aspect of the present invention, an apparatus for generating an identifier of a femto base station in a wireless communication system includes an identifier checking unit for identifying an identifier of a macro base station to which the femto base station is connected, and a system of the femto base station and the macro base station. An offset setting unit for setting an offset of the femto base station by comparing a frame number and an identifier generator for generating an identifier of the femto base station by using a predetermined portion of the identifier of the macro base station and the offset; It is characterized in that the configuration.

According to a seventh aspect of the present invention, a method for restoring an identifier of a femto base station in a macro base station of a wireless communication system includes: checking an offset of a femto base station to which the terminal is connected in a signal received from a terminal; And identifying an identifier of the femto base station by using the identifier and the offset of the macro base station.

According to an eighth aspect of the present invention, an apparatus for restoring an identifier of a femto base station in a macro base station of a wireless communication system includes: a receiving unit receiving a signal from a terminal, and the terminal receiving the signal from the terminal through the receiving unit. And a controller for checking an offset of the connected femto base station, an identifier checking unit for identifying an identifier of the macro base station, and an identifier generator for generating an identifier of the femto base station using the identifier and the offset of the macro base station. It is characterized by.

As described above, the terminal of the wireless communication system distinguishes femto base stations having reused physical cell identity (PCID) by considering offsets according to system base number (SFN) of the base station and the femto base station, thereby defining the PCID defined in the 3GPP standard. While minimizing synchronous performance while minimizing synchronous performance and retrieving Global Cell IDentity (GCID), complexity and delay can be reduced rather than cell search for distinguishing femto base stations.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, the present invention describes a technique for distinguishing a femto base station using a system frame number offset of a femto base station and a macro base station in a wireless communication system. Here, the SFN offset means the difference between the SFN of the femto base station and the SFN of the macro base station.

In the wireless communication system, a plurality of femto cells may be installed in one macro cell as shown in FIG. 1.

1 illustrates a configuration of a wireless communication system including a femto cell according to the present invention.

As illustrated in FIG. 1, the macro base station 100 manages one macro cell. In this case, a plurality of femto cells managed by each of the femto base stations 110, 120, 130, 140, and 150 may be installed in the macro cell.

When there are a plurality of femto cells in the macro cell, the macro base station 100 is a physical layer cell identifier (Physical Cell IDentity: hereinafter, PCID) to each of the femto base stations (110, 120, 130, 140, 150) And global cell identifier (hereinafter, referred to as GCID). At this time, the macro base station 100 may be assigned to the femto base stations (110, 120, 130, 140, 150) overlapping the PCID, but to the femto base stations (110, 120, 130, 140, 150) You must assign a unique GCID. For example, when the number of femto base stations to allocate the PCID is greater than the number of PCIDs that the macro base station 100 can allocate to the femto base stations, the macro base station 100 is femto base station 1 (110), femto The same PCID 15 may be assigned to base station 3 130 and femto base station 4 140. However, the macro base station 100 should assign different global cell identifiers to the femto base stations.

In the above-described embodiment, the macro base station determines the PCIDs and GCIDs of the femto base stations included in the macro cell managed by the macro base station and assigns them to each femto base station. In another embodiment, the wireless communication system may allocate PCIDs and GCIDs of femto base stations using separate servers.

As described above, the macro base station 100 may allocate duplicate PCIDs to the femto base stations 110, 120, 130, 140, and 150. Therefore, the wireless communication system should control so that the terminal can distinguish femto base stations having the same PCID. For example, a femto base station having the same PCID has different SFN offsets based on the SFN of the macro base station as shown in FIG. 2 according to its SFN. Accordingly, the terminal may distinguish each femto base station using SFNs of femto base stations having the same PCID.

2 illustrates an SFN of a femto base station having the same PCID in a wireless communication system according to an exemplary embodiment of the present invention.

As shown in FIG. 2, femto base stations having the same PCID in one macro cell have different SFNs. For example, as shown in FIG. 1, femto base station 1 110, femto base station 3 130, and femto base station 4 140 have the same PCID. At this time, the femto base station 1 (110), femto base station 3 (130) and femto base station 4 (140) has a different SFN.

The SFN offsets of the femto base stations set by comparing the SFN 200 of the macro base station with the SFNs 210, 220, and 230 of the femto base stations are 0, 4, 8, and have different values. Accordingly, the UE can distinguish each femto base station using the SFN offsets of the femto base stations as shown in FIG. 3.

As described above, the wireless communication system sets SFN offsets of femto base stations having the same PCID based on the SFN of the macro base station so as to distinguish the femto base station. Therefore, femto cells included in one macro cell are synchronized with the macro cell. At this time, the macro cell and the femto cell maintain synchronization using periodic communication and its own clock in the femto cell.

Also, the wireless communication system allocates the same PCID to femto base stations having different SFNs or assigns different SFNs to femto base stations having the same PCID so that femto base stations having the same PCID can have different SFN offsets. . For example, when different SFNs are allocated to femto base stations having the same PCID, the macro base station allocates different SFNs by using GCIDs of femto base stations having duplicate PCIDs.

Hereinafter, a description will be given of a method of operating a terminal for distinguishing a femto base station from the wireless communication system.

3 illustrates a procedure for identifying a femto base station in a wireless communication system according to an embodiment of the present invention. In the following description, it is assumed that the terminal can distinguish a femto base station and a macro base station.

Referring to FIG. 3, the terminal first checks the PCID of the femto base station through which the signal is received in step 301. For example, the terminal checks the PCID of the femto base station through the primary synchronization channel and the secondary synchronization channel. Here, the primary synchronization channel represents a Primary Syncronization Signal (P-SS) defined in the 3rd Gerneration Partnership Project (3GPP) standard, and the secondary synchronization channel represents a Second Syncronization Signal (S-SS).

After checking the PCID of the femto base station, the terminal checks the SFN of the femto base station in step 303. In this case, the terminal checks the SFN of the femto base station through a broadcast signal provided through a physical broadcasting channel (PBCH) of the femto base station.

In step 305, the terminal checks the SFN of the macro base station including the femto base station. At this time, the terminal checks the SFN of the macro base station through a broadcast signal provided through the physical layer broadcast channel of the macro base station.

After checking the SFNs of the femto base station and the macro base station, the terminal proceeds to step 307 to compare the SFN of the macro base station with the SFN of the femto base station and sets the SFN offset of the femto base station. That is, the terminal sets the SFN offset of the femto base station based on the SFN of the macro base station.

After setting the SFN offset of the femto base station, the terminal proceeds to step 309 and checks the femto base station according to the SFN offset in the femto base station having the same PCID as the PCID of the femto base station confirmed in step 301. For example, the terminal includes the SFN offset table of femto base stations having the same PCID. Accordingly, the terminal selects a femto base station according to the SFN offset from the SFN offset table.

After checking the femto base station, the terminal proceeds to step 311 and transmits the PCID information, SFN offset information and system information of the femto base station to the macro base station. In another embodiment, the terminal may transmit only the SFN offset information and system information of the femto base station to the macro base station. Here, the system information includes information for requesting to perform a handover to the identified femto base station. That is, when the macro base station receives a signal only from terminals connected to a femto base station located in its cell, the terminal does not need to transmit PCID information of the femto base station to the macro base station.

Thereafter, the terminal terminates the present algorithm.

As described above, the terminal distinguishes femto base stations using the PCID and the SFN of the femto base station. In this case, since 3GPP standards define 4096 SFNs and 504 PCIDs, one macro cell may install up to 4096 × 504 femto base stations.

In the above-described embodiment, it is assumed that the UE has another femto base station having the same PCID as the femto base station confirmed through the cell search. In another embodiment, the terminal may check whether there is another femto base station having the same PCID as the found femto base station according to the PCID information of the femto base stations provided from the macro base station. Therefore, the UE can distinguish the discovered femto base station by comparing the SFNs of the femto base station and the macro base station only when another femto base station having the same PCID as the found femto base station exists.

Hereinafter, the configuration of a terminal for distinguishing a femto base station in the wireless communication system will be described.

4 is a block diagram of a terminal for identifying a femto base station in a wireless communication system according to the present invention.

As shown in FIG. 4, the terminal includes a duplexer 400, a receiver 410, a transmitter 420, a controller 430, an SFN checker 440, an offset setting unit 450, and a base station identification unit 460. It is configured to include).

The duplexer 400 transmits a transmission signal provided from the transmitter 420 through an antenna according to a duplexing method, and provides a reception signal from the antenna to the receiver 410.

The receiver 410 converts the received signal provided from the duplexer 400 into a baseband signal and provides the signal to the controller 430. For example, when an orthogonal frequency division multiplexing scheme is used in the wireless communication system, the receiver 410 includes an RF processor, an analog / digital converter, an OFDM demodulator, and a decoder. In this case, the RF processor converts a high frequency signal provided from the duplexer 400 into a baseband analog signal. The analog-to-digital converter converts an analog signal provided from the RF processor into digital sample data and outputs the digital sample data. The OFDM demodulator converts the sample data of the time domain provided from the analog-to-digital converter through the fast Fourier transform and converts the sample data of the time domain into data of the frequency domain. The decoder demodulates and decodes the signal provided from the OFDM demodulator according to a predetermined modulation level (MCS level).

The controller 430 controls the overall operation of the terminal. In addition, although not shown, the control unit 430 checks the PCID of the femto base station through a signal provided through the receiving unit 410 including the PCID checking unit. For example, the PCID verification unit confirms the PCID of the femto base station through the primary synchronization channel and the secondary synchronization channel.

Thereafter, the controller 430 controls the SFN checking unit 440, the offset setting unit 450, and the base station identification unit 460 to identify femto base stations assigned the same PCID as the PCID. For example, the controller 430 checks whether there is another femto base station having the same PCID as the PCID checked by the PCID checking unit according to the PCID information of the femto base stations provided from the macro base station. If there is another femto base station having the same PCID as the PCID confirmed by the PCID checking unit, the controller 430 sets an offset with the SFN checking unit 440 to identify the femto base stations assigned the same PCID. The unit 450 and the base station identification unit 460 are operated.

The SFN checker 440 checks the SFNs of the macro base station and the femto base station through the broadcast signal provided through the control unit 430. The offset setting unit 450 sets the SFN offset of the femto base station by comparing the SFN of the macro base station with the SFN of the femto base station. The base station identification unit 460 uses femto base stations having the same PCID as the PCID of the femto base station identified by the controller 430 using the SFN offset information provided from the offset setting unit 450. Identifies the base station. For example, the base station identification unit 460 includes SFN offset tables of femto base stations having the same PCID. Accordingly, the base station identification unit 460 selects a femto base station according to the SFN offset provided from the offset setting unit 450 in the SFN offset table.

The transmitter 420 converts a transmission signal into a high frequency signal under the control of the controller 430 and provides the converted signal to the duplexer 400. For example, when the orthogonal frequency division multiplexing is used in the wireless communication system, the transmitter 420 includes an encoder, an OFDM modulator, a digital / analog converter, and an RF processor. At this time, the encoder is coded and modulated according to the modulation level (MCS level) and outputs the transmission signal under the control of the controller 430. The OFDM modulator converts the frequency domain data received from the encoder into inverse time Fourier transform into sample data (OFDM symbols) in the time domain and outputs the transformed frequency domain data. The digital-to-analog converter converts the sample data provided from the OFDM modulator into an analog signal and outputs the analog signal. The RF processor converts a baseband analog signal provided from the digital / analog converter into a high frequency signal and outputs the high frequency signal.

At this time, the transmitter transmits the SFN offset value set by the offset setting unit 450, the PCID checked by the PCID checker, and the system information of the femto base station to the macro base station under the control of the controller 430. In another embodiment, the transmitter may transmit the SFN offset value set by the offset setting unit 450 and the system information of the femto base station to the macro base station under the control of the controller 430.

In the above configuration, the controller 430 controls the SFN checking unit 440, the offset setting unit 450, and the base station identification unit 460. That is, the controller 430 may perform the functions of the SFN checking unit 440, the offset setting unit 450, and the base station identification unit 460. In the present invention, it is separately configured to describe each function separately. Therefore, in actual implementation, all of them may be configured to be processed by the controller 430, and only some of them may be configured to be processed by the controller 430.

As described above, the UE may distinguish the femto base stations having the same PCID by using the PCIDs and SFN offsets of the femto base stations. At this time, the macro base station should identify the femto base station to which the terminal is connected. For example, the macro base station preconfigures and stores the GCID mapping information of the femto base stations with respect to the PCID and the SFN offset of the femto base stations. Accordingly, the macro base station may check the GCID of the femto base station corresponding to the PCID and the SFN offset of the femto base station provided from the terminal in the GCID mapping information.

In another embodiment, the macro base station may restore the GCID of the femto base station through the PCN and the SFN offset of the femto base station provided from the terminal. In this case, the wireless communication system may configure the GCID of the femto base station as shown in FIG. 11 so that the macro base station can recover the GCID of the femto base station using only the PCID and SFN offset information of the femto base station.

11 illustrates a configuration of a global cell identifier of a femto base station in a wireless communication system according to an embodiment of the present invention.

As shown in FIG. 11, the GCID 1100 of the macro base station and the GCID 1110 of the femto base station may be configured with 28 bits. Here, it is assumed that the femto base station is located in a macro cell managed by the macro base station.

In this case, the GCID 1110 of the femto base station is configured to include a portion of the GCID 1100 of the macro base station and the SFN offset of the femto base station set based on the SFN of the macro base station. For example, the upper 16 bits of the GCID 1110 of the femto base station have the same value as the lower 16 bits of the GCID 1100 of the macro base station. The lower 12 bits of the GCID 1110 of the femto base station have the same value as the SFN offset set by comparing the SFN of the macro base station with the SFN of the femto base station.

In the above-described embodiment, it is assumed that the GCID 1100 of the macro base station and the GCID 1110 of the femto base station are composed of 28 bits, but the GCID 1100 of the macro base station and the GCID 1110 of the femto base station have different lengths. It may be configured.

The following description will describe a method for configuring a GCID of a femto base station as described above. In this case, the GCID of the femto base station may be generated directly by the femto base station or generated by a separate server and assigned to the femto base station. In the following description, it is assumed that a femto base station directly generates its own GCID.

12 illustrates a procedure for configuring a global cell identifier of a femto base station in a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 12, the femto base station checks the GCID of the macro base station managing the macro cell where it is located in step 1201. For example, the femto base station may check the GCID of the macro base station from the broadcast signal provided from the macro base station. In another embodiment, the femto base station may be provided with the GCID of the macro base station from the network.

After checking the GCID of the macro base station, the femto base station checks the SFN and its SFN of the macro base station in step 1203.

After checking the SFNs of the macro base station and itself, the femto base station proceeds to step 1205 and compares the SFN of the macro base station with its own SFN and sets the SFN offset. That is, the femto base station sets its SFN offset based on the SFN of the macro base station.

After setting the SFN offset, the femto base station proceeds to step 1207 to generate a GCID using a part of the GCID of the macro base station and its SFN offset. For example, the femto base station generates its own GCID by setting the lower 16 bits of the GCID of the macro base station to the upper 16 bits of the GCID and the SFN offset to the lower 12 bits of the GCID.

Thereafter, the femto base station terminates the present algorithm.

As described above, when the femto base station generates its own GCID, the femto base station includes a GCID checker and a GCID generator. At this time, the GCID checker checks the GCID of the macro base station managing the macro cell where the femto base station is located. For example, the GCID checker may check the GCID of the macro base station from the broadcast signal provided from the macro base station. In another embodiment, the GCID checker may check the GCID of the macro base station provided from the network.

The GCID generation unit generates a GCID of the femto base station by using a part of the GCID of the macro base station provided from the GCID checking unit and the SFN offset of the femto base station provided from the offset determining unit 450. For example, the GCID generating unit sets the lower 16 bits of the GCID of the macro base station to the upper 16 bits of the GCID and sets the SFN offset to the lower 12 bits of the GCID to generate the GCID of the femto base station.

As described above, when the GCID of the femto base station is configured using the GCID and the SFN offset of the macro base station, the macro base station is a femto base station through the PCID and SFN offset of the femto base station provided from the terminal as shown in FIG. You can restore the GCID of.

13 illustrates a procedure for restoring a global cell identifier of a femto base station in a macro base station of a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 13, the macro base station determines whether information of a femto base station to which the terminal is connected is received from the terminal in step 1301.

If the information of the femto base station is received, the macro base station checks the PCID of the femto base station and the SFN offset information of the femto base station from the information of the femto base station provided in step 1303. Here, the SFN offset information of the femto base station means the SFN offset of the femto base station set based on the SFN of the macro base station.

In step 1305, the macro base station determines whether the PCID is a PCID allocated to the femto base station. That is, the macro base station checks whether the femto base station accessed by the terminal is located in the macro cell managed by the terminal through the PCID.

If the femto base station is located in its macro cell, the macro base station checks its GCID in step 1307.

After confirming its own GCID, the macro base station proceeds to step 1309 to restore the GCID of the femto base station using a part of its own GCID and the SFN offset of the femto base station. For example, the macro base station sets the lower 16 bits of its GCID to the upper 16 bits of the GCID of the femto base station and sets the SFN offset to the lower 12 bits of the GCID of the femto base station to generate the GCID of the femto base station. .

If the femto base station is located in an adjacent macro cell, the macro base station checks the GCID of the neighboring macro base station to which the PCID is allocated in step 1311. Here, it is assumed that the macro base station knows both GCID information of neighboring macro base stations and PCID information included in the neighboring macro base stations.

After checking the GCID of the neighboring macro base station, the macro base station proceeds to step 1309 to restore the GCID of the femto base station by using a part of the GCID of the neighboring macro base station and the SFN offset of the femto base station. For example, the macro base station sets the lower 16 bits of the GCID of the neighboring macro base station to the upper 16 bits of the GCID of the femto base station and sets the SFN offset to the lower 12 bits of the GCID of the femto base station. Create

The macro base station then terminates this algorithm.

Hereinafter, the configuration of the macro base station for generating the GCID of the femto base station by using the PCID and SFN offset information of the femto base station provided from the terminal.

14 is a block diagram of a macro base station for recovering a global cell identifier of a femto base station in a wireless communication system according to the present invention.

As illustrated in FIG. 14, the terminal includes a duplexer 1400, a receiver 1410, a transmitter 1420, a controller 1430, a GCID checker 1440, and a GCID generator 1450.

The duplexer 1400 transmits a transmission signal provided from the transmitter 1420 through an antenna according to a duplexing scheme, and provides a reception signal from the antenna to the receiver 1410.

The receiver 1410 converts the received signal provided from the duplexer 1400 into a baseband signal and provides the converted signal to the controller 1430. For example, when using orthogonal frequency division multiplexing in the wireless communication system, the receiver 1410 includes an RF processor, an analog / digital converter, an OFDM demodulator, and a decoder. In this case, the RF processor converts a high frequency signal provided from the duplexer 1400 into a baseband analog signal. The analog-to-digital converter converts an analog signal provided from the RF processor into digital sample data and outputs the digital sample data. The OFDM demodulator converts the sample data in the time domain provided from the analog-to-digital converter through the fast Fourier transform and converts the sample data in the frequency domain to data in the frequency domain. The decoder demodulates and decodes the signal provided from the OFDM demodulator according to a predetermined modulation level (MCS level).

The controller 1430 controls the overall operation of the macro base station. In addition, the controller 1430 controls an operation for identifying a femco base station to which the terminal is connected by using femto base station information provided from the terminal through the receiver 1410.

The GCID checker 1440 checks the GCID of the macro base station to which the PCID is allocated according to the PCID information provided from the controller 1430. For example, when the PCID received from the controller 1430 is a PCID assigned to the femto base stations, the GCID checker 1440 checks its own GCID. On the other hand, when the PCID received from the controller 1430 is a PCID assigned by the neighboring macro base station to the femto base station, the GCID checking unit 1440 checks the GCID of the neighboring macro base station to which the PCID is allocated. Here, it is assumed that the GCID checker 1440 knows both GCID information of neighboring macro base stations and PCID information included in the neighboring macro base stations.

The GCID generation unit 1450 restores the GCID of the femto base station using the GCID of the macro base station provided from the GCID checking unit 1440 and the SFN offset information of the femto base station provided from the control unit 1430. For example, the GCID generation unit 1450 sets the lower 16 bits of the GCID of the macro base station to the upper 16 bits of the GCID of the femto base station, and sets the SFN offset to the lower 12 bits of the GCID of the femto base station. Generate a GCID of the femto base station.

The transmitter 1420 converts a transmission signal into a high frequency signal and provides the duplexer 1400 under the control of the controller 1430. For example, when the orthogonal frequency division multiplexing scheme is used in the wireless communication system, the transmitter 1420 includes an encoder, an OFDM modulator, a digital / analog converter, and an RF processor. In this case, the encoder encodes and modulates the transmission signal according to a modulation level (MCS level) under the control of the controller 1430 and outputs the modulated signal. The OFDM modulator converts the frequency domain data received from the encoder into inverse time Fourier transform into sample data (OFDM symbols) in the time domain and outputs the transformed frequency domain data. The digital-to-analog converter converts the sample data provided from the OFDM modulator into an analog signal and outputs the analog signal. The RF processor converts a baseband analog signal provided from the digital / analog converter into a high frequency signal and outputs the high frequency signal.

In the above-described embodiment, the wireless communication system has described a technique for configuring the GCID of the femto base station and recovering the GCID of the femto base station in the macro base station. In this case, the wireless communication system may configure a Closed Subscriber Group (CSG) ID of the femto base stations in the same manner, and restore the CSG ID of the femto base station from the macro base station.

As described above, the UE may identify the femto base station assigned the same PCID by using the SFN offsets of the femto base station and the macro base station. In this case, the terminal identifies the femto base station using the SFN offsets of the femto base station and the serving macro base station. Here, the serving macro base station means a macro base station to which the femto base station is synchronized.

If the terminal moves from the macro base station other than the serving macro base station to the femto base station, the terminal may receive a signal of the femto base station before the signal of the serving macro base station. In this case, since the terminal sets the SFN offset of the femto base station based on the SFN of the other macro base station, it may set an incorrect SFN offset for the femto base station.

To solve this problem, macro base stations provide SFN offset information with neighboring macro base stations to terminals, as shown in FIG. 15.

15 illustrates a configuration of a wireless communication system including a femto cell according to another embodiment of the present invention.

As shown in FIG. 15, the wireless communication system includes three macro base stations 1500, 1510, and 1520. In addition, the femto base station 1540 located in the overlapped service area of the macro base stations 1500, 1510, and 1520 selects and synchronizes the macro base station 1 1500. That is, the macro base station 1 1500 is a serving macro base station of the femto base station 1540.

The macro base stations 1500, 1510, and 1520 store SFN offset information calculated by comparing SFNs with adjacent macro base stations. For example, since the macro base stations 1500, 1510, and 1520 are not synchronized with each other as shown in FIG. 16, SFN offsets are set by comparing SFNs with adjacent macro base stations.

If the terminal 1550 moves to the service area of the macro base station 2 1510 (1560), the macro base station 2 1510 transmits SFN offset information with neighboring macro base stations to the terminal 1550. do. For example, the macro base station 2 1510 transmits SFN offset information with neighboring macro base stations to the terminal 1550 according to a request of the terminal 1550.

The terminal 1550 updates its neighbor base station management information by using SFN offset information of the macro base stations adjacent to the macro base station 2 1510. In this case, the terminal 1550 knows information of macro base stations adjacent to the macro base station 2 1510 and femto base stations adjacent to the macro base station 2 1510. Accordingly, the terminal 1550 updates neighbor base station management information using only SFN offset information of neighboring macro base stations received from the macro base station 2 1510. Here, the neighbor base station management information means a fingerprint including SFN offset information of neighboring macro base stations as shown in FIG. 19. In addition, the adjacent femto base station information includes adjacent femto base station to which the terminal 1550 can move and serving macro base station information of the femto base station.

As described above, the terminal 1550 knows SFN offset information and femto base station information adjacent to the macro base stations 1500 and 1520 adjacent to the macro base station 2 1510. Therefore, when the terminal 1550 moves to the femto base station 1540 (1570), the terminal 1550 is SFN information of the macro base station 2 (1510), the macro base station 2 (1510) and the serving macro base station The SFN offset of the femto base station 1540 may be set using SFN offset information with respect to 1500 and SFN information of the femto base station 1540. For example, the terminal may set the SFN offset of the femto base station 1540 by using Equation 1 below.

Where Denotes an SFN offset of the femto base station 1540, S ₁ denotes SFN information of the macro base station 2 1510, and S _off indicates that the macro base station 2 1510 and the serving macro base station 1500 Indicate SFN offset information, and S ₂ indicates SFN information of the femto base station 1540.

16 illustrates SFNs of macro base stations in a wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 16, (a) of FIG. 16 illustrates SFN offsets of other neighbor macro base stations 1610 and 1620 set by the macro base station 1 1600 based on its SFN. b) shows SFN offsets of other adjacent macro base stations 1600 and 1620 that macro base station 2 1610 sets based on its SFN. In this case, the macro base station 1 1600 and the macro base station 2 1610 set the SFN offset based on a portion where the overlapping SFNs of other adjacent macro base stations are long. If the length of one frame is 10ms, the macro base station 1 1600 and the macro base station 2 1610 set the SFN difference between the frames overlapping each other for 5 ms or more as the SFN offset.

Accordingly, as illustrated in (a) of FIG. 16, the macro base station 1 1600 has an SFN offset of 10 with macro base station 2 1610 and an SFN offset of 20 with macro base station 3 1620. .

In addition, as shown in FIG. 16B, the macro base station 2 1610 has an SFN offset of -10 with the macro base station 1 1600 and an SFN offset of the macro base station 3 1620 and 10. Has

When setting the SFN offset with the neighboring macro base stations as described above, the macro base stations may set the SFN offset by acquiring SFN information of the neighboring macro base stations using a radio link or a wired link or a terminal. For another example, the SFN offset of the macro base stations may be set and managed by a separate control unit that manages neighbor cell list (NCL) information of the macro base stations.

The following description describes a method for the UE to obtain SFN offset information of macro base stations.

17 illustrates a procedure for obtaining SFN offsets of macro base stations in a terminal of a wireless communication system according to an embodiment of the present invention.

As illustrated in FIG. 17, when the terminal 1700 moves to a service area of the macro base station 1720, the terminal 1700 may acquire PCID information of the macro base station 1720 (step 1731). .

After acquiring the PCID of the macro base station 1720, the terminal 1700 checks whether there is SFN offset information between serving macro base stations of the femto base stations adjacent to the macro base station 1720 in the neighbor base station management information (1733). step).

If the SFN offset information does not exist, the terminal 1700 transmits a registration request message and an SFN offset information request message to the macro base station 1720 (step 1735). In this case, the terminal 1700 may include the SFN offset information request message in the registration request message and transmit the same.

On the other hand, if not shown, but the SFN offset information, the terminal 1700 transmits only a registration request message to the macro base station 1720.

When the macro base station 1720 receives the registration request message and the SFN offset information request message, and accepts the registration of the terminal 1700, the macro base station 1720 receives the registration response message and the SFN offset between the serving macro base stations. The information is transmitted (step 1737).

When the registration response message and the SFN offset information are received, the terminal 1700 updates neighbor base station management information using the SFN offset information (step 1739). That is, the terminal 1700 updates SFN offset information between the serving macro base station of the adjacent femto base station and the macro base station 1720 in the neighbor base station management information configured as shown in FIG. 19.

19 illustrates a configuration of neighbor base station management information of a terminal in a wireless communication system according to an embodiment of the present invention.

As shown in FIG. 19, the neighbor base station management information 1900 of the terminal includes a white list 1910 indicating adjacent femto base stations and SFN offset information 1920 indicating SFN offset information of macro base stations adjacent to femto base stations. It is configured by.

The white list 1910 includes closed subscriber group (CSG) ID information and GCID information of femto base stations adjacent to the terminal.

The SFN offset information 1920 includes PCID information, GCID information, and SFN offset information set based on a serving macro base station of neighboring macro base stations of the femto base station registered in the white list 1910. For example, in FIG. 15, the SFN offset information 1920 of the femto base station 1540 of the terminal 1550 is the PCID of the macro base station 1 1500, the macro base station 2 1510, and the macro base station 3 1520. Information, GCID information, and SFN offset information set based on the serving macro base station. In this case, since the macro base station 1 1500 is a serving macro base station of the femto base station, the terminal sets the SFN offsets of the macro base station 2 1510 and the macro base station 3 1520 based on the SFN of the macro base station 1 1500. Save it.

The following description describes a method for identifying the femto base station by using the SFN offset information of the femto base station in the terminal.

18 illustrates a procedure for distinguishing a femto base station in a wireless communication system according to another embodiment of the present invention.

Referring to FIG. 18, the terminal proceeds to step 1801 and checks whether a PCID of the femto base station is received by moving to a service area of the femto base station. For example, the terminal checks the PCID of the femto base station through the primary synchronization channel and the secondary synchronization channel. Accordingly, the terminal checks whether the primary synchronization channel and the secondary synchronization channel are received in step 1801. Here, the primary synchronization channel represents a Primary Syncronization Signal (P-SS) defined in the 3rd Gerneration Partnership Project (3GPP) standard, and the secondary synchronization channel represents a Second Syncronization Signal (S-SS).

After confirming the PCID of the femto base station, the terminal proceeds to step 1803 to identify the serving macro base station of the femto base station in the neighbor base station management information.

In step 1805, the terminal determines whether the macro base station to which the terminal is registered is changed. That is, the terminal checks whether the macro base station registered before moving to the femto base station and the serving macro base station identified in step 1803 are different. Here, the macro base station registered before moving to the femto base station includes a serving macro base station of the femto base station registered before the terminal moves to the femto base station.

If the macro base station is not changed, the terminal proceeds to step 1809 to check the SFN of the femto base station. For example, the terminal checks the SFN of the femto base station through a broadcast signal provided through a physical broadcasting channel (PBCH) of the femto base station.

After checking the SFN of the femto base station, the terminal proceeds to step 1811 to compare the SFN of the femto base station with the SFN of the serving macro base station identified in step 1803 to set the SFN offset of the femto base station. In this case, when the femto base station is assigned a duplicate PCID, the terminal identifies the femto base station using the SFN offset of the femto base station.

On the other hand, when the macro base station is changed in step 1805, the terminal proceeds to step 1807 to check the SFN offset information of the serving macro base station through the neighbor base station management information. That is, the terminal checks SFN offset information between the macro base station and the serving macro base station registered before moving to the femto base station through neighbor base station management information.

After checking the SFN offset information of the serving macro base station, the terminal proceeds to step 1809 to check the SFN of the femto base station.

After checking the SFN of the femto base station, the terminal proceeds to step 1811 using the SFN of the macro base station, the SFN offset information of the serving macro base station and the SFN of the femto base station registered before moving to the femto base station. Sets the SFN offset of the femto base station. For example, the terminal may set the SFN offset of the femto base station by using Equation 1. In this case, when the femto base station is assigned a duplicate PCID, the terminal identifies the femto base station using the SFN offset of the femto base station.

Thereafter, the terminal terminates the present algorithm.

As described above, the macro base stations provide SFN offset information with neighboring macro base stations to the terminal so that the terminal can set the correct SFN offset for the femto base station. Accordingly, the macro base station further includes an offset setting unit and an offset storage unit in the configuration shown in FIG. 14. The offset setting unit compares the SFNs of neighboring macro base stations obtained by using a radio link or a wired link or a terminal with its own SFN and sets the SFN offset for each neighboring macro base stations. The offset storage unit stores SFN offset information for neighboring macro base stations set by the offset setting unit.

In addition, the terminal is configured to further include a neighbor base station management information control unit in the configuration shown in FIG. The neighbor base station management information control unit serves the macro macro base station and the serving macro base station of the adjacent femto base stations in the neighbor base station management information configured as shown in FIG. Updates the SFN offset information with.

Accordingly, the offset setting unit 450 checks whether the macro base station is changed when moving to the femto base station. That is, the offset setting unit 450 checks whether the macro base station registered before moving to the femto base station and the serving macro base station of the femto base station are different. Here, the macro base station registered before moving to the femto base station includes a serving macro base station of the femto base station registered before the terminal moves to the femto base station.

If the macro base station is not changed, the offset setting unit 450 sets the SFN offset of the femto base station by comparing the SFN of the femto base station with the SFN of the serving macro base station.

On the other hand, when the macro base station is changed, the offset setting unit 450 uses the SFN of the macro base station, the SFN offset information of the serving macro base station and the SFN of the femto base station registered before the terminal moves to the femto base station. Set the SFN offset of the femto base station.

As described above, the terminal distinguishes the femto base station by using SFN offsets of femto base stations having the same PCID. In this case, the femto base station may operate in a transmission mode (TX) or not in a transmission mode (TX) according to the location of an active terminal (OFF). For example, when an active terminal communicates through a femto base station, the femto base station performs a transmission mode. On the other hand, when the active terminal is located in the macro cell where the femto base station is located but does not communicate through the femto base station, the femto base station periodically broadcast signal considering the SFN of the femto base station as shown in FIG. Send it. In addition, when the active terminal moves to the outside of the macro cell where the femto base station is located, the femto base station stops the transmission mode.

5 shows a period for transmitting a broadcast signal in a femto base station of a wireless communication system according to an embodiment of the present invention.

As shown in FIG. 5, when the active terminal is located in the macro cell where the femto base station is located but does not communicate through the femto base station, the femto base station periodically transmits a broadcast signal in consideration of SFN. That is, the femto base station 500 or 510 or 520 transmits a broadcast signal at a time point 501 or 511 or 521 when its SFN becomes zero. For example, the femto base stations recognize an absolute time according to a macro base station and a time point determined according to Equation 2 below as a start point (SFN = 0) of signal transmission. Accordingly, the femto base stations periodically transmit a broadcast signal from the start point of the signal transmission.

Here, x represents the GCID of the femto base station, and d represents a variable to determine the SFN offset.

Since the femto base stations have different GCIDs as shown in Equation 2, when the module is calculated with the same variable, the femto base stations may have different SFN offsets. Thus, a plurality of femto base stations may transmit broadcast signals at different times.

In addition, the wireless communication system may determine SFNs of femto base stations having the same PCID by using the absolute time according to the macro base station and the SFN offset generated using Equation (2).

The following description describes the procedure for switching the transmission mode according to the position of the terminal operating in the femto base station. 6 illustrates a procedure for stopping the transmission mode by the femto base station performing the transmission mode.

6 illustrates a procedure for switching a transmission mode in a femto base station of a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 6, the femto base station first transmits a signal to a terminal located in a service area by performing TX in a transmission mode in step 601.

In operation 603, the femto base station determines whether a response signal for the transmitted signal is received from the terminal that transmitted the signal.

If the response signal is received, the femto base station returns to step 601 and maintains transmission mode.

On the other hand, if the response signal is not received for a certain time, the femto base station proceeds to step 605 and periodically transmits a broadcast signal in consideration of its SFN. That is, the femto base station transmits a broadcast signal when its SFN becomes zero.

Thereafter, the femto base station proceeds to step 607 and checks whether a mode switch message is received from the macro base station managing the macro cell to which the femto base station belongs. For example, the femto base station determines whether a message indicating transmission mode interruption (TX off) is received from the macro base station.

If the mode switch message is not received, the femto base station returns to step 703 and checks whether a response signal to the signal broadcast in step 705 is received.

On the other hand, when the mode switch message is received, the femto base station proceeds to step 709 to stop (Tx off) the transmission mode.

Thereafter, the femto base station terminates the present algorithm.

The following description describes the procedure for switching the transmission mode according to the position of the terminal operating in the femto base station. In this case, FIG. 7 describes a procedure for performing a transmission mode by a femto base station which has stopped a transmission mode.

7 illustrates a procedure for switching transmission modes in a femto base station of a wireless communication system according to another embodiment of the present invention.

Referring to FIG. 7, the femto base station maintains a state in which the transmission mode is stopped (TX off) in step 701.

In this case, the femto base station proceeds to step 703 to check whether a mode switch message is received from the macro base station managing the macro cell to which it belongs. For example, the femto base station determines whether a message indicating transmission mode execution (TX on) is received from the macro base station.

If the mode switch message is not received, the femto base station returns to step 701 and maintains a transmission mode interruption state.

On the other hand, when the mode switch message is received, the femto base station proceeds to step 705 and periodically transmits a broadcast signal in consideration of its SFN. That is, the femto base station transmits a broadcast signal when its SFN becomes zero.

After transmitting the broadcast signal, the femto base station proceeds to step 707 to determine whether a response signal for the broadcast signal is received from the terminal.

If the response signal is not received for a predetermined time, the femto base station returns to step 705 and periodically transmits a broadcast signal in consideration of its SFN.

On the other hand, when the response signal is received, the femto base station proceeds to step 709 to switch to the transmission mode (TX on) to transmit a signal to the terminal located in the service area.

Thereafter, the femto base station terminates the present algorithm.

The wireless communication system may switch the transmission mode of the femto base station in consideration of the handover of the terminal. For example, as shown in FIG. 8, the femto base station switches the transmission mode to TX off according to handover of the terminal.

8 illustrates a procedure for switching a transmission mode of a femto base station in a wireless communication system according to an embodiment of the present invention.

As shown in FIG. 8, the terminal 800 performs communication through the femto base station 802 (step 811). When the handover of the terminal 800 is confirmed during communication with the terminal 800 (step 813), the femto base station 802 requests a handover of the terminal 800 to the serving macro base station 804. (Step 815). For example, the femto base station 802 determines whether the terminal 800 will handover in consideration of the channel state with the terminal 800. In another embodiment, the femto base station 802 confirms the handover of the terminal 800 according to whether the terminal 800 requests a handover. Here, the serving macro base station 804 means a macro base station that manages a macro cell where the femto base station 802 is located.

After requesting the handover of the terminal 800 to the serving macro base station 804, the femto base station 802 and the serving macro base station 804 perform a handover procedure to transmit the terminal 800 to the serving macro base station. Handover to step 804 (step 817).

Thereafter, the serving macro base station 804 registers the handover of the terminal 800 to the mobility management entity (MME) 808 (step 819). In this case, the femto base station 802 releases the registration of the terminal 800 to the MME 808 (step 821).

When the terminal 800 hands over to the serving macro base station 804, the MME 808 notifies the femto base station 802 of the handover completion of the terminal 800 (step 823). In this case, when the serving macro base station 804 registers the handover of the terminal 800 and the femto base station 802 releases the registration of the terminal 800, the MME 808 receives the terminal ( It is recognized that the handover of 800) is completed.

When the femto base station 802 is notified of the completion of the handover, the femto base station 802 periodically transmits a broadcast signal (step 825). That is, the femto base station 802 transmits a broadcast signal when its SFN becomes zero.

Thereafter, when the handover of the terminal 800 is confirmed during communication with the terminal 800 (step 827), the serving macro base station 804 hands over the terminal 800 to the target macro base station 806. (Step 829). For example, the serving macro base station 804 determines whether the terminal 800 will handover in consideration of the channel state with the terminal 800. In another embodiment, the serving macro base station 804 checks the handover of the terminal 800 according to whether the terminal 800 requests a handover. Here, the target macro base station 806 means a macro base station that manages a macro cell to which the terminal 800 hands over among macro cells adjacent to a macro cell where the femto base station 802 is located.

After requesting the handover of the terminal 800 to the target macro base station 806, the serving macro base station 804 and the target macro base station 806 perform a handover procedure to transfer the terminal 800 to the target macro. Handover to the base station 806 (step 831).

Thereafter, the target macro base station 806 registers the handover of the terminal 800 with the MME 808 (step 833). In this case, the serving macro base station 804 releases the registration of the terminal 800 to the MME 808 (step 835).

When the terminal 800 hands over to the target macro base station 806, the MME 808 instructs the femto base station 802 to switch modes (step 837). For example, the MME 808 transmits a message indicating transmission mode interruption (TX off) to the femto base station 802.

When the mode switch indication signal is received from the MME 808, the femto base station 802 stops (Tx off) the transmission mode (step 839).

The wireless communication system may switch the transmission mode of the femto base station in consideration of the handover of the terminal. For example, as shown in FIG. 9, the femto base station switches the transmission mode to TX on according to handover of the terminal.

9 illustrates a procedure for switching a transmission mode of a femto base station in a wireless communication system according to another embodiment of the present invention.

As illustrated in FIG. 9, the terminal 900 performs communication through the serving macro base station 906 (step 911). When the handover of the terminal 900 is confirmed during communication with the terminal 900 (step 913), the serving macro base station 906 requests a handover of the terminal 900 to the target macro base station 904. (Step 915). For example, the serving macro base station 906 determines whether the terminal 900 will handover in consideration of the channel state with the terminal 900. In another embodiment, the serving macro base station 906 checks the handover of the terminal 900 according to whether the terminal 900 requests a handover.

After requesting the handover of the terminal 900 to the target macro base station 904, the serving macro base station 906 and the target macro base station 904 perform a handover procedure to transfer the terminal 900 to the target macro. Handover to the base station 904 (step 917).

Thereafter, the target macro base station 904 registers the handover of the terminal 900 with the MME 908 (step 919). In this case, the serving macro base station 906 releases the registration of the terminal 900 to the MME 908 (step 921).

When the terminal 900 hands over to the target macro base station 904, the MME 908 instructs the femto base station 902 to switch modes (step 923). For example, the MME 908 transmits a message indicating transmission mode performance (TX on) to the femto base station 902. Here, the femto base station 902 refers to a femto base station that manages a femto cell located in a macro cell managed by the target macro base station 904.

When the mode change indication signal is received from the MME 908, the femto base station 902 periodically transmits a broadcast signal (step 925). That is, the femto base station 902 transmits a broadcast signal when its SFN becomes zero.

Thereafter, the femto base station 902 checks whether a response signal for the broadcast signal is received from the terminal. In this case, when the response signal is received (step 927), the femto base station 902 requests the handover of the terminal 900 to the target base station 904 (step 931).

After requesting the handover of the terminal 900 to the target macro base station 904, the femto base station 902 and the target macro base station 904 perform a handover procedure to transfer the terminal 900 to the target macro base station. Handover to step 904 (step 931).

Thereafter, the femto base station 902 registers the handover of the terminal 900 to the MME 908 (step 933). In this case, the target macro base station 904 releases the registration of the terminal 900 to the MME 908 (step 935).

After registering the handover of the terminal 900 with the MME 908, the femto base station 902 switches the transmission mode to Tx on (step 937).

Thereafter, the femto base station 902 communicates with the terminal 900.

Hereinafter, a description will be given of an apparatus for switching a transmission mode according to a location of a terminal operating in a femto base station.

10 is a block diagram of a femto base station for switching a transmission mode in a wireless communication system according to the present invention.

As illustrated in FIG. 10, the terminal includes a duplexer 1000, a receiver 1010, a transmitter 1020, and a controller 1030.

The duplexer 1000 transmits a transmission signal provided from the transmitter 1020 through an antenna according to a duplexing scheme, and provides a reception signal from the antenna to the receiver 1010.

The receiver 1010 converts a received signal provided from the duplexer 1000 into a baseband signal and provides the converted signal to the controller 1030. For example, when an orthogonal frequency division multiplexing scheme is used in the wireless communication system, the receiver 1010 includes an RF processor, an analog / digital converter, an OFDM demodulator, and a decoder. In this case, the RF processor converts a high frequency signal provided from the duplexer 1000 into a baseband analog signal. The analog-to-digital converter converts an analog signal provided from the RF processor into digital sample data and outputs the digital sample data. The OFDM demodulator converts the sample data in the time domain provided from the analog-to-digital converter through the fast Fourier transform and converts the sample data in the frequency domain to data in the frequency domain. The decoder demodulates and decodes the signal provided from the OFDM demodulator according to a predetermined modulation level (MCS level).

The controller 1030 controls the overall operation of the terminal. In addition, the control unit 1030 controls the performance (TX on) or stop (TX off) of the transmission mode according to the position of the terminal operating. That is, the controller 1030 controls to switch the transmission mode according to the transmission mode switch message provided from the macro base station. For example, when a message indicating transmission mode stop (TX off) is received through the receiving unit 1010, the controller 1030 controls to stop the transmission mode. On the other hand, when a message indicating the transmission mode execution (TX on) is received through the receiving unit 1010, the control unit 1030 controls to perform the transmission mode that was stopped.

In addition, when performing the transmission mode, the controller 1030 controls the operation of the transmission mode according to the position of the active terminal. For example, when the active terminal communicates through the femto base station, the controller 1030 controls to perform a transmission mode. On the other hand, when the active terminal is located in the macro cell where the femto base station is located but does not communicate through the femto base station, the controller 1030 controls to periodically transmit a broadcast signal. In this case, when the response signal for the transmission signal is not received from the terminal for a predetermined time, the controller 1030 recognizes that the terminal is located in the macro cell but does not perform communication through the femto base station.

The transmitter 1020 converts a transmission signal into a high frequency signal and provides the duplexer 1000 under the control of the controller 1030. For example, when using the orthogonal frequency division multiplexing scheme in the wireless communication system, the transmitter 1020 includes an encoder, an OFDM modulator, a digital / analog converter, and an RF processor. In this case, the encoder encodes and modulates the transmission signal according to a modulation level (MCS level) under the control of the controller 1030 and outputs the modulated signal. The OFDM modulator converts the frequency domain data received from the encoder into inverse time Fourier transform into sample data (OFDM symbols) in the time domain and outputs the transformed frequency domain data. The digital-to-analog converter converts the sample data provided from the OFDM modulator into an analog signal and outputs the analog signal. The RF processor converts a baseband analog signal provided from the digital / analog converter into a high frequency signal and outputs the high frequency signal.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a diagram illustrating a configuration of a wireless communication system including a femto cell according to the present invention;

2 is a diagram illustrating an SFN of a femto base station having the same PCID in a wireless communication system according to an embodiment of the present invention;

3 is a diagram illustrating a procedure for distinguishing a femto base station in a wireless communication system according to an embodiment of the present invention;

4 is a block diagram of a terminal for distinguishing a femto base station in a wireless communication system according to the present invention;

5 is a diagram illustrating a period for transmitting a broadcast signal in a femto base station of a wireless communication system according to an embodiment of the present invention;

6 is a diagram illustrating a procedure for switching a transmission mode in a femto base station of a wireless communication system according to an embodiment of the present invention;

7 is a diagram illustrating a procedure for switching a transmission mode in a femto base station of a wireless communication system according to another embodiment of the present invention;

8 is a diagram illustrating a procedure for switching a transmission mode of a femto base station in a wireless communication system according to an embodiment of the present invention;

9 is a diagram illustrating a procedure for switching a transmission mode of a femto base station in a wireless communication system according to another embodiment of the present invention;

10 is a block diagram of a femto base station for switching a transmission mode in a wireless communication system according to the present invention;

11 illustrates a configuration of a global cell identifier of a femto base station in a wireless communication system according to an embodiment of the present invention;

12 is a diagram illustrating a procedure for configuring a global cell identifier of a femto base station in a wireless communication system according to an embodiment of the present invention;

13 is a diagram illustrating a procedure for recovering a global cell identifier of a femto base station in a macro base station of a wireless communication system according to an embodiment of the present invention;

14 is a block diagram of a macro base station for recovering a global cell identifier of a femto base station in a wireless communication system according to the present invention;

15 is a diagram illustrating a configuration of a wireless communication system including a femto cell according to another embodiment of the present invention;

16 illustrates SFNs of macro base stations in a wireless communication system according to an embodiment of the present invention;

17 is a diagram illustrating a procedure for obtaining SFN offsets of macro base stations in a terminal of a wireless communication system according to an embodiment of the present invention;

18 is a diagram illustrating a procedure for distinguishing a femto base station in a wireless communication system according to another embodiment of the present invention; and

19 is a diagram illustrating a configuration of neighbor base station management information of a terminal in a wireless communication system according to an embodiment of the present invention.

Claims (41)

A method for distinguishing a femto base station from a terminal of a wireless communication system, When the femto base station is discovered, checking a physical layer cell identifier (Physical Cell IDentity) of the femto base station; Checking a system frame number of the femto base station and the macro base station; Setting an offset of the femto base station by comparing the system frame numbers of the femto base station and the macro base station; And identifying a femto base station according to the offset among at least one femto base station assigned the same physical layer cell identifier as the physical layer cell identifier. The method of claim 1, Checking the physical layer cell identifier, And checking the physical layer cell identifier through the first synchronization signal and the second synchronization signal identified in the signal received from the femto base station. The method of claim 2, The first synchronization signal includes a primary syncronization signal (P-SS), The secondary synchronization channel, characterized in that it comprises a second syncronization signal (S-SS). The method of claim 1, Checking the system frame number, Identifying a system frame number of the femto base station and a system frame number of the macro base station in each broadcast signal provided through the physical layer broadcasting channel of the femto base station and the physical layer broadcasting channel of the macro base station. Way. The method of claim 1, After checking the physical layer cell identifier of the femto base station, checking whether there is another femto base station to which the physical layer cell identifier is allocated; If there is another femto base station to which the physical layer cell identifier is allocated, the method proceeds to checking the system frame number. The method of claim 1, And transmitting at least one of the identified system information of the femto base station, offset information of the femto base station, and a physical layer cell identifier of the femto base station to the macro base station. The method of claim 1, After checking the physical layer cell identifier of the femto base station, further comprising the step of identifying a serving macro base station that the femto base station is synchronized, And if the macro base station to which the terminal is registered is the same as the serving macro base station, checking the system frame number. The method of claim 7, wherein When the macro base station to which the terminal is registered and the serving macro base station are not the same, offset information on the system frame number of the registered macro base station and the femto base station and the system frame number of the serving macro base station and the registered macro base station Process of checking, And setting an offset of the femto base station by using offset information on system frame numbers of the registered macro base station and the femto base station and system frame numbers of the serving macro base station and the registered macro base station. How to. An apparatus for identifying a femto base station in a wireless communication system, Receiving unit for receiving a signal from the femto base station and the macro base station, When the femto base station is searched through the receiver, the femto base station is determined by considering a physical cell ID of the femto base station and an offset according to a system frame number by the femto base station and the macro base station. A device comprising a control unit for distinguishing. The method of claim 9, The control unit, A physical layer cell identifier checking unit for identifying a physical layer cell identifier of the femto base station; A system frame number checking unit for checking a system frame number of the femto base station and the macro base station; An offset setting unit for setting an offset of the femto base station by comparing the system frame numbers of the femto base station and the macro base station; And a base station identification unit for identifying a femto base station according to the offset among at least one femto base station assigned the same physical layer cell identifier as the physical layer cell identifier. The method of claim 10, The physical layer cell identifier check unit, characterized in that for confirming the physical layer cell identifier through the first synchronization signal and the second synchronization signal confirmed in the signal provided from the femto base station. The method of claim 11, The first synchronization signal includes a primary syncronization signal (P-SS), The secondary synchronization channel, characterized in that it comprises a second syncronization signal (S-SS). The method of claim 10, The system frame number confirming unit may identify the system frame number of the femto base station and the system frame number of the macro base station in each broadcast signal provided through the physical layer broadcast channel of the femto base station and the physical layer broadcast channel of the macro base station. Characterized in that the device. The method of claim 10, The offset setting unit may be configured to set the offset of the femto base station by comparing the system frame numbers of the femto base station and the macro base station when the serving macro base station to which the femto base station is synchronized and the macro base station to which the terminal is registered are the same. Characterized in that the device. The method of claim 10, The offset setting unit, Further comprising a neighbor base station management information control unit for controlling the offset information for the system frame number of neighboring macro base stations, If the serving macro base station to which the femto base station is synchronized and the macro base station to which the terminal is registered are not the same, the system macro frame number of the registered macro base station and the femto base station and the serving macro base station and the registered macro base station And an offset of the femto base station is set using offset information on a system frame number. The method of claim 9, And a transmitter configured to transmit at least one of system information of the femto base station, offset information of the femto base station, and a physical layer cell identifier of the femto base station to the macro base station. In the transmission mode control method in a femto base station of a wireless communication system, When performing a transmission mode (TX on), checking whether a response signal to a signal transmitted to at least one terminal is received; If the response signal is not received, periodically transmitting a broadcast signal; When the first mode switch message is received from the macro base station, stopping the transmission mode (TX off). The method of claim 17, The process of transmitting the broadcast signal, And periodically transmitting a broadcast signal according to a system frame number. The method of claim 17, Checking whether a second mode switch message is received from the macro base station when the transmission mode is stopped; Periodically transmitting a broadcast signal when the second mode switch message is received; Switching to a transmission mode (TX on) when a response signal to the broadcast signal is received. The method of claim 19, The process of transmitting the broadcast signal, And periodically transmitting a broadcast signal according to a system frame number. In a femto base station apparatus of a wireless communication system, A transmitter for transmitting a transmission signal to at least one terminal, A receiver which receives a response signal to the transmission signal; And a controller for controlling to periodically transmit a broadcast signal when the response signal is not received. The method of claim 21, The control unit, characterized in that for controlling to transmit the broadcast signal periodically in accordance with the System Frame Number (System Frame Number). The method of claim 21, The control unit, if the first mode switching message is received from the macro base station via the receiving unit, characterized in that for controlling (TX off) the transmission mode. The method of claim 23, wherein The controller may be configured to periodically transmit a broadcast signal when a second mode switch message is received from the macro base station through the receiver while the transmission mode is stopped. The method of claim 24, The control unit, if the response signal for the broadcast signal is received through the receiving unit, characterized in that the control to switch to the transmission mode (TX on). A method for generating an identifier of a femto base station in a wireless communication system, Checking an identifier of a macro base station to which the femto base station is connected; Setting an offset of the femto base station by comparing a system frame number of the femto base station and a macro base station; Generating an identifier of the femto base station by using a predetermined portion of the identifier of the macro base station and the offset. The method of claim 26, The identifier is characterized in that the global cell identifier (Global Cell IDentity) or CSG (Closed Subscriber Group) identifier. The method of claim 26, Generating an identifier of the femto base station, Setting the lower 16 bits constituting the identifier of the macro base station to the upper 16 bits of the identifier of the femto base station; And setting the offset of the femto base station to the lower 12 bits of the femto base station. An apparatus for generating an identifier of a femto base station in a wireless communication system, An identifier checker for checking an identifier of a macro base station to which the femto base station is connected; An offset setting unit configured to set an offset of the femto base station by comparing a system frame number of the femto base station and a macro base station; And an identifier generator for generating an identifier of the femto base station by using a predetermined portion of the identifier of the macro base station and the offset. The method of claim 29, The identifier is characterized in that the global cell identifier (Global Cell IDentity) or CSG (Closed Subscriber Group) identifier. The method of claim 29, And the identifier generating unit sets the lower 16 bits constituting the identifier of the macro base station to the upper 16 bits of the identifier of the femto base station and sets the offset of the femto base station to the lower 12 bits of the femto base station. A method for restoring an identifier of a femto base station in a macro base station of a wireless communication system, Checking an offset of a femto base station to which the terminal is connected from a signal received from the terminal; Checking the identifier of the macro base station; And generating an identifier of the femto base station by using the identifier of the macro base station and the offset. The method of claim 32, The identifier is characterized in that the global cell identifier (Global Cell IDentity) or CSG (Closed Subscriber Group) identifier. The method of claim 32, The offset is characterized in that the terminal indicates the information set according to the system frame number of the femto base station based on the system frame number (System Frame Number) of the macro base station. The method of claim 32, Checking the identifier of the macro base station, Identifying a macro cell in which the femto base station is located by using a physical layer cell identifier (Physical Cell IDentity) of the femto base station identified in the signal received from the terminal; When the femto base station is located in a macro cell of a neighboring macro base station, checking an identifier of the neighboring macro base station; If the femto base station is located in its macro cell, the method comprising the step of identifying its identifier. The method of claim 32, Generating an identifier of the femto base station, Setting the lower 16 bits constituting the identifier of the macro base station to the upper 16 bits of the identifier of the femto base station; And setting the offset of the femto base station to the lower 12 bits of the femto base station. An apparatus for recovering an identifier of a femto base station in a macro base station of a wireless communication system, Receiving unit for receiving a signal from the terminal, A control unit for checking an offset of a femto base station to which the terminal is connected from a signal received from the terminal through the receiving unit; An identifier checking unit for checking an identifier of the macro base station, And an identifier generator configured to generate an identifier of the femto base station by using the identifier of the macro base station and the offset. The method of claim 37, wherein The identifier is characterized in that the global cell identifier (Global Cell IDentity) or CSG (Closed Subscriber Group) identifier. The method of claim 37, wherein The control unit is characterized in that for checking the offset of the femto base station set by the terminal based on the system frame number (System Frame Number) of the macro base station according to the system frame number of the femto base station. The method of claim 37, wherein The identifier check unit, When the femto base station is located in the macro cell of the neighboring macro base station according to the physical layer cell identifier (Physical Cell IDentity) of the femto base station confirmed in the signal provided from the terminal, the identifier of the neighboring macro base station is checked, And when the femto base station is located in its macro cell, identifying its identifier. The method of claim 37, wherein And the identifier generating unit sets the lower 16 bits constituting the identifier of the macro base station to the upper 16 bits of the identifier of the femto base station and sets the offset of the femto base station to the lower 12 bits of the femto base station.

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