WO2009091149A1

WO2009091149A1 - Method of detecting a location of a mobile station in a separated-type radio access station, separated-type radio access station, and main unit for supporting the same

Info

Publication number: WO2009091149A1
Application number: PCT/KR2008/007845
Authority: WO
Inventors: Byeong Seog Pyo; Kwang Seob Yoo
Original assignee: Posdata Co., Ltd.
Priority date: 2007-12-31
Filing date: 2008-12-31
Publication date: 2009-07-23
Also published as: KR20090073592A

Abstract

A method of detecting a location of a subscriber station in a separated-type radio access station, the subscriber station connected with the separated-type radio access station, wherein the method comprises receiving power spectrum information for an uplink frame from a remote unit; obtaining identification information for a sub-carrier corresponding to a frequency whose power value is higher than a reference value from the power spectrum information; and determining that the subscriber station is located within a coverage area of the remote unit when it is detected with reference to mapping information for the sub-carrier allocated to the subscriber station that the subscriber station is mapped to the identification information.

Description

METHOD OF DETECTING A LOCATION OF A MOBILE

STATION IN A SEPARATED-TYPE RADIO ACCESS STATION,

SEPARATED-TYPE RADIO ACCESS STATION, AND MAIN

UNIT FOR SUPPORTING THE SAME Technical Field

[1] The present invention relates to a method of detecting a location of a subscriber station in a separated-type radio access station, and a separated-type radio access station and main unit supporting the same. More particularly, the present invention relates to a method of detecting a remote unit connected with a subscriber station, and a separated-type radio access station and main unit supporting the same. Background Art

[2] If a general radio access station (hereinafter, refereed to as "RAS") is installed in an area with a relatively small number of subscribers in comparison to a predetermined number of subscribers which can be covered virtually, it may cause a waste of resource. In order to prevent the waste of resource, a remote unit (hereinafter, referred to as "RU") is installed in the area with the relatively small number of subscribers. In this case, the RAS comprised of the RU and a main unit (hereinafter, referred to as "MU") controlling the RU is referred to as a separated-type RAS.

[3] FIG. 1 is a block diagram illustrating a general separated-type RAS. The general separated type RAS includes an MU 102; RUs 104, 112, 114, and 116; a connecting cable 106 such as an optical cable or coaxial cable to connect the MU with the RU; an antenna 108 through which a data frame is received and transmitted between a subscriber station (hereinafter, referred to as "SS") and the separated-type RAS; and a GPS antenna 110.

[4] The MU 102 is in IP-communication with an access control router (hereinafter, referred to as "ACR"), wherein the MU 120 function as a path for transmitting and receiving traffic data, and control information related with the RAS and ACR.

[5] When a base-band I/Q signal is input to the RU 104, the RU 104 converts the input base-band I/Q signal into an intermediate frequency signal (hereinafter, referred to as "IF signal"), and then converts the IF signal into a radio frequency signal (hereinafter, referred to as "RF signal") by using modulation method such as a quadrature phase shift keying (hereinafter, referred to as "QPSK") or queued access method (hereinafter, referred to as "QAM"). Also, the RU 104 converts and demodulates the data received through the antenna 108 into the RF signal, and separates the base-band I/Q signal from the RF signal.

[6] The general separated-type RAS can secure the wider coverage area using the plurality of RUs 104, 112, 114, and 116 in comparison to the coverage area by one RU 104.

[7] In this case, even though it is possible to detect that the SS is located within the coverage area of the separated-type RAS including the MU 102, which coverage area of RUs 104, 112, 114, and 116 includes the SS located therein can not be detected.

[8] Accordingly, there is no definite method of detecting the corresponding RU 104 connected with the SS. Also, there is a problem that a probability of detecting the location of SS is proportionally lowered according to the increasing number of RUs installed for the enlargement of coverage area. Disclosure of Invention Technical Problem

[9] Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a method of detecting a location of a subscriber station in a separated-type radio access station, and a separated-type radio access station and main unit supporting the same.

[10] An object of the present invention is to provide a method of detecting a location of

SS in a separated-type RAS, in which a corresponding remote unit connected with the SS can be detected from the separated-type RAS including the plurality of remote unit, and a separated-type radio access station and main unit supporting the same, which is capable of preventing one or more problems of the related art. Technical Solution

[11] To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a method of detecting a location of a subscriber station in a separated-type radio access station, the subscriber station connected with the separated-type radio access station, comprises receiving power spectrum information for an uplink frame from a remote unit; obtaining identification information for a sub-carrier corresponding to a frequency whose power value is higher than a reference value from the power spectrum information; and determining that the subscriber station is located within a coverage area of the remote unit when it is detected with reference to mapping information for the sub-carrier allocated to the subscriber station that the subscriber station is mapped to the identification information.

[12] In another aspect of the present invention, a separated-type radio access station comprises a separated-type radio access station comprises a remote unit for measuring power spectrum information for an uplink frame; and a main unit for obtaining mapping information between an SS (subscriber station) and a sub-carrier allocated to the SS, and to determine that the SS is located within a coverage area of the remote unit when it is detected that the SS is mapped to identification information for the sub- carrier with respect to the mapping information, wherein the identification information for the sub-carrier is identification information corresponding to a frequency whose power in the power spectrum information is higher than a reference value. [13] In another aspect of the present invention, a main unit to detect a location of an

SS(subscriber station) in a separated-type radio access station comprises a power information analyzer for obtaining identification information for a sub-carrier corresponding to a frequency whose power value is higher than a reference value from power spectrum information of an uplink frame; and an SS location detecting unit for checking mapping information corresponding to the identification information for the sub-carrier, and to detect the location of the SS in mapping information.

Advantageous Effects

[14] According to the present invention, the identification information for the specific sub-carrier can be obtained by using the power spectrum information of the uplink frame measured in the remote unit, whereby the SS can detect the remote unit connected with the SS. [15] Even though the coverage area of RAS is enlarged by the increasing number of remote units installed, it is possible to raise a probability of detecting the location of

SS.

Brief Description of Drawings

[16] FIG. 1 is a block diagram illustrating a general separated-type RAS.

[17] FIG. 2 is a block diagram illustrating a separated-type RAS according to one embodiment of the present invention. [18] FIG. 3 illustrates a procedure of obtaining power spectrum information received in a power information analyzer and identification information for a sub-carrier. [19] FIG. 4 illustrates structures of downlink frame and uplink frame according to one embodiment of the present invention. [20] FIG. 5 illustrates a procedure of obtaining power spectrum information received in a threshold value comparator and power spectrum information above a threshold value. [21] FIG. 6 is a block diagram illustrating a separated-type RAS according to another embodiment of the present invention. [22] FIG. 7 is a flow chart illustrating a method of detecting a location of SS in a separated-type RAS according to one embodiment of the present invention.

Best Mode for Carrying out the Invention [23] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[24] Hereinafter, a separated-type RAS according to the present invention and a method of detecting a location of SS therein will be explained with reference to the accompanying drawings.

[25] FIG. 2 is a block diagram illustrating a separated-type RAS according to one embodiment of the present invention.

[26] The separated-type RAS according to one embodiment of the present invention includes an MU 202; RUs 220, 234, 236, and 238; a connecting cable 223 such as an optical cable or coaxial cable to connect the MU with the RUs; an antenna 235 through which a data frame is received and transmitted between an SS (not shown) and the RU 220; and a GPS antenna 232.

[27] The MU 202 includes a clock unit 204, an ACR interface unit 206, an RAS controller

208, a digital processor 210, a first interface board 212, a power information analyzer 214, and an SS location detecting unit 216.

[28] The clock unit 204 receives a reference signal from a GPS through the GPS antenna

232, and generates and provides a clock necessary for each component of the separated-type RAS, thereby synchronizing the data frame transmitted and received between the SS and the separated-type RAS.

[29] The ACR interface unit 206 is in IP-communication with an ACR (not shown), wherein the ACR interface unit 206 function as a path for transmitting and receiving traffic data, and control information related with the RAS and ACR.

[30] The RAS controller 208 performs functions, for example, control and state management of the RAS, and call processing of the RAS.

[31] In one embodiment of the present invention, the RAS controller 208 and the clock unit 204 may be integrated into one unit, which may be a main control and clock unit (hereinafter, referred to as "MCCU") including an RAS management processor (hereinafter, referred to as "RMP") to control general operations of the RAS, for example, control over internal components of the RAS, source allocation, call processing, RAS management, or ACR interfacing.

[32] The RAS controller 208 receives identification information for the RU connected with the SS from the SS location detecting unit 216, whereby the RAS controller 208 is capable of being aware in which coverage area of RU the SS is located among the plurality of RUs 220, 234, 236, and 238. Also, when receiving a request for transmission of the SS-location information from the external, the RAS controller 208 provides the aware SS-location information.

[33] The digital processor 210 processes MAC and PHY signals of the data frame, and transmits and receives a base-band digital I/ Q signal. In one embodiment of the present invention, the digital processor 210 corresponds to a block for managing a MAC/PHY modem, which may be a digital channel card unit (hereinafter, referred to as "DCCU") to perform functions of data random, convolution/convolution-turbo channel coding/decoding, interleaving, and sub-channel allocation for FUSC/PUSC.

[34] Together with a second interface board 218, the first interface board 212 is used for matching information transmitted and received between the MU 202 for performing a digital data processing in a base-band and the RU 220 for performing an analog data processing in an RF-band. In one embodiment of the present invention, the first interface board 212 can be embodied based on a common public radio interface (hereinafter, referred to as "CPRI") standard.

[35] The power information analyzer 214 receives power spectrum information measured in an uplink burst duration of an uplink frame from the RU 220 through the first interface board 212. At this time, the power spectrum information may be transmitted together with the identification information for the RU 220 which transmits the power spectrum information, or the power spectrum information may include identification information for the uplink frame at which the power spectrum information is measured.

[36] The power information analyzer 214 obtains identification information for a sub- carrier corresponding to a frequency whose power value is higher than a reference value in the power spectrum information.

[37] FIG. 3 illustrates a procedure of obtaining the power spectrum information received from the power information analyzer 214, and the identification information for the sub-carrier.

[38] Referring to FIG. 3, the power spectrum information includes power values 302, 304, and 306 according to the frequency.

[39] Since an orthogonal frequency division multiplexing access symbol (hereinafter, referred to as "OFDMA symbol") of the uplink burst duration is transmitted by the plurality of sub-carriers, the power spectrum measured in the uplink burst duration has the predetermined powers 302 and 304 in the frequency band corresponding to the sub- carrier (first sub-carrier and second sub-carrier).

[40] The power information analyzer 214 obtains information for the frequency 302 and

304 whose power value is higher than the reference value in the power spectrum information, and ignores information for the frequency 306 whose power value is lower than the reference value in the power spectrum information since it is regarded as noise. Also, the power information analyzer 214 transmits identification information for the sub-carrier corresponding to the information for the frequency 302 and 304 whose power value is higher than the reference value to the SS location detecting unit [41] In one embodiment of the present invention, the power information analyzer 214 can transmit only information for the frequency 302 and 304 whose power value is higher than the reference value to the SS location detecting unit 216.

[42] Referring once again to FIG. 2, when the SS location detecting unit 216 receives the identification information for the sub-carrier corresponding to the information for the frequency 302 and 304 whose power value is higher than the reference value from the power information analyzer 214, the SS location detecting unit 216 detects whether the SS mapped to the identification information for the sub-carrier exists or not.

[43] In one embodiment of the present invention, the SS location detecting unit 216 can directly obtain the identification information for the corresponding sub-carrier using the information for the frequency whose power value received from the power information analyzer 214 is higher than the reference value, and can detect whether the SS mapped to the identification information for the sub-carrier exists or not.

[44] When the SS mapped to the identification information for the sub-carrier exists, it is determined that the SS is located within the coverage area of the RU 220 which transmits the identification information for the sub-carrier. In this case, mapping information between the SS and the sub-carrier allocated to the SS is previously obtained and stored in the SS location detecting unit 216.

[45] Accordingly, after detecting whether or not the SS allocating the corresponding sub- carrier exists using identification information for the received sub-carrier and mapping information, when the SS allocating the corresponding sub-carrier exists, it can be determined that the SS is connected with the RU 220.

[46] A detailed method of detecting a location of SS will be explained with reference to

FIG. 4.

[47] FIG. 4 illustrates structures of downlink and uplink frames according to one embodiment of the present invention.

[48] Referring to FIG. 4, the structures of downlink and uplink frames are based on IEEE

802.16 or WiMAX standard. In this case, the downlink frame includes uplink MAP information elements 404a and 404b (hereinafter, referred to as "UL_MAP IE") in an uplink MAP 402 (hereinafter, referred to as "UL_MAP"), wherein the UL_MAP IEs 404a and 404b include information for uplink burst regions 410a and 410b allocated to the SSs.

[49] When the uplink burst regions 410a and 410b are allocated to the SSs in the

UL_MAP IEs 404a and 404b, sub-carriers 406 and 408 to be used in the uplink burst regions 410a and 410b are determined based on a pre-defined rule.

[50] For convenience of explanation in FIG. 4, supposing that the corresponding SS to be a target for detecting its location is referred to as the first SS, and the uplink burst region 410a of uplink burst #2 and the UL_MAP IE 404a corresponding to the uplink burst 410a of uplink burst #2 are mapped to the first SS.

[51] The first SS transmits uplink data on the sub-carrier 406 allocated to the SS in the uplink burst region 410a allocated to the first SS.

[52] Accordingly, the SS location detecting unit 216 is capable of being aware of the uplink burst region 410a allocated to the first SS in the UM_MAP IE 404a, whereby the SS location detecting unit 216 is capable of being aware of the sub-carrier 406 to be used by the first SS in the corresponding uplink frame.

[53] A detailed method of detecting the location of the first SS will be explained. First, the

SS location detecting unit 216 obtains mapping information between the first SS and the sub-carrier 406 allocated to the first SS in UL_MAP IE 404a of the downlink frame, and then stores the obtained mapping information therein.

[54] Then, if the first SS transmits the uplink frame on the sub-carrier 406, and a power information measuring unit 228 in the RU 220 measures the power spectrum information for the corresponding uplink burst regions 410a and 410b at the predetermined power spectrum measuring point, the power spectrum information have the power value to be higher than the reference value at the frequencies corresponding to the sub-carrier 406 and the other sub-carrier 408 for the uplink frame of the second SS.

[55] Then, the SS location detecting unit 216 obtains the identification information for the sub-carrier 406 and 408 corresponding to the frequency whose power value is higher than the reference value from the power information analyzer 214.

[56] If it is detected that the sub-carrier 406 of the uplink burst region 410 allocated to the first SS is mapped to the first SS 406 in the pre-stored mapping information, the SS location detecting unit 216 detects that the first SS is located within the coverage area of the RU 220 which transmits the power spectrum information.

[57] At this time, the SS location detecting unit 216 can receive the identification information for the RU 220 together with the power spectrum information, and the identification information for the uplink frame included in the power spectrum information from the power information analyzer 214; and can use them for the procedure of detecting the location of the first SS.

[58] According as the identification information for the RU 220 is used for the procedure of detecting the location of first SS, it is possible to identify the RU 220 which transmits the power spectrum information. Also, whether or not the mapping information corresponds to the uplink frame can be detected in identification information for the uplink frame.

[59] The aforementioned embodiment of the present invention discloses that the power information analyzer 214 or the SS location detecting unit 216 is separately provided from the RAS controller 208. However, in a modified embodiment of the present invention, the power information analyzer 214 or the SS location detecting unit 216 may be integrated into the RAS controller 208.

[60] Referring once again to FIG. 2, the RU 220 includes a second interface board 222, a modulator/demodulator 224, an RF processor 226, the power information measuring unit 228, and a threshold value comparator 230. In one embodiment of the present invention, the RU 220 may be a remote radio head (hereinafter, referred to as "RRH") or remote optic unit (hereinafter, referred to as "ROU").

[61] At this time, the RU 220 is connected with the MU 202 in a daisy-chain or star shape with the other RUs 234, 236, and 238.

[62] Together with the first interface board 212, the second interface board 222 is used for matching information transmitted and received between the MU 202 and the RU 220. In one embodiment of the present invention, the second interface board 222 can be embodied based on the CPRI standard.

[63] When the base-band I/Q signal is input to the modulator/demodulator 224, the modulator/demodulator 224 converts the input base-band I/Q signal into an analog or digital intermediate frequency signal (hereinafter, referred to as "analog or digital IF signal") by using modulation method such as QPSK or QAM. Meanwhile, the analog or digital IF signal is input to the modulator/demodulator 224, the modulator/demodulator 224 demodulates the analog or digital IF signal so as to separate the baseband I/Q signal.

[64] The RF processor 226 converts the IF signal into an RF signal, and then amplifies the converted RF signal by a high-output mode. Also, the RF processor 226 converts the RF signal into the IF signal by a low-noise amplification. Thus, the RF processor 226 enables the data to be transmitted and received between the SS and the RU 220 through the antenna 235.

[65] The power information measuring unit 228 measures the power spectrum information in the uplink burst region of the uplink frame. At this time, the power spectrum information corresponds to power information above the threshold value, from which noise components are removed by the threshold value comparator 230.

[66] In this case, the power spectrum information can be measured based on a Fast

Fourier Transform (FFT) analysis method.

[67] In one embodiment of the present invention, the power spectrum information may include the identification information for the uplink frame corresponding to the target for measuring its power spectrum.

[68] The threshold value comparator 230 generates the power information by removing the noise components below the threshold value from the power spectrum information primarily measured by the power information measuring unit 228, and transmits the generated power information to the power information measuring unit 228. [69] FIG. 5 illustrates a procedure of obtaining the power spectrum information received in the threshold value comparator 230 and the power spectrum information above the threshold value.

[70] Referring to FIG. 5, the power spectrum information includes power values 502, 504, and 506 according to the frequency.

[71] Since the OFDMA symbol of the uplink burst duration is transmitted on the plurality of sub-carriers 502 and 504, the power spectrum measured in the uplink burst duration by the power information measuring unit 228 has the predetermined powers 502 and 504 in the frequency band corresponding to the sub-carrier.

[72] The threshold value comparator 230 ignores information 506 whose power value is lower than the reference value in the power spectrum information since it is regarded as noise. Also, the threshold value comparator 230 transmits power spectrum information 502 and 504 whose power value is higher than the reference value to the power information measuring unit 228.

[73] The aforementioned embodiment of the present invention discloses that the power information measuring unit 228 is separated from the threshold value comparator 230. However, a modified embodiment of the present invention may disclose that the power information measuring unit 228 and the threshold value comparator 230 are integrated into one unit. Mode for the Invention

[74] FIG. 6 is a block diagram illustrating a separated-type RAS according to another embodiment of the present invention. Among components of FIG. 6, the components which perform the same functions as those of FIG. 2 will not be described so as to avoid repetitiveness.

[75] An MU 602 includes an SS location detecting unit 604. The SS location detecting unit 604 stores mapping information between an SS and a sub-carrier allocated to the SS, and receives identification information for the sub-carrier from a power information analyzer 608 of an RU 606.

[76] When the SS is mapped to the received identification information for the sub-carrier with reference to the mapping information, the SS location detecting unit 604 detects that the SS is positioned within the coverage area of the RU which transmits the identification information for the sub-carrier.

[77] In one embodiment of the present invention, the identification information for the sub-carrier includes identification information for an uplink frame, whereby the SS location detecting unit 604 can identify whether or not the mapping information corresponds to the uplink frame.

[78] In one embodiment of the present invention, the identification information for the sub-carrier is received together with the identification information for the RU 606. Thus, the SS location detecting unit 604 can identify the RU 606, which transmits the identification information for the sub-carrier, using identification information for the RU 606, and also can detect that the SS is located within the coverage area of the RU 606.

[79] The RU 606 includes the power information analyzer 608 and a threshold value comparator 610.

[80] The power information analyzer 608 measures power spectrum information in an uplink burst region of the uplink frame. Then, the power information analyzer 608 obtains the identification information for the sub-carrier corresponding to a frequency whose power value is higher than a reference value from the power spectrum information, and transmits the obtained identification information to the SS location detecting unit 604.

[81] The threshold value comparator 610 determines power information whose power value is lower than the reference value as noise, and then removes the power information whose power value is lower than the reference value from the power spectrum information primarily generated by the power information analyzer 608, thereby generating power spectrum information above the threshold value. Then, the threshold value comparator 610 transmits the generated power spectrum information above the threshold value to the power information analyzer 608.

[82] FIG. 7 is a flow chart illustrating a method of detecting a location of SS in a separated-type RAS according to one embodiment of the present invention.

[83] First, the mapping information between the SS and the sub-carrier allocated to the SS is stored in the MU in step of S702. In this case, the mapping information can be obtained in the UL_MAP IE of the UL_MAP.

[84] Then, the power spectrum information for the uplink frame is obtained from the RU in step of S704. In one embodiment of the present invention, the power spectrum information can be measured based on an FFT analysis method.

[85] In one embodiment of the present invention, the power spectrum information can include the identification information for the uplink frame, wherein the power spectrum information corresponds to power information above the threshold value, from which noise components are removed.

[86] In one embodiment of the present invention, the power spectrum information may be measured at the uplink burst region of the uplink frame.

[87] In one embodiment of the present invention, the RU may be the RRH or ROU, and the RU may be connected with the MU in the daisy-chain or star shape.

[88] In one embodiment of the present invention, the RU may be interfaced with the MU through the CPRI board. [89] Thereafter, the identification information for the sub-carrier can be obtained in the power spectrum information in step of S706. At this time, the MU obtains the identification information for the sub-carrier corresponding to the frequency whose power value is higher than the reference value from the power spectrum information.

[90] Next, it is detected by the MU in mapping information whether or not the SS is mapped to the identification information for the sub-carrier received in the SS in step of S708.

[91] When it is detected by the MU that the SS is mapped to the identification information for the sub-carrier received in the SS, it is determined that the SS is located within the coverage area of the RU which transmits the power spectrum information in step of S710a.

[92] When it is detected by the MU that the SS is not mapped to the identification information for the sub-carrier received in the SS, it is determined that the SS is not located within the coverage area of the RU which transmits the power spectrum information in step of S710b.

[93] In one embodiment of the present invention, the RU transmits the power spectrum information together with the identification information for the RU to the MU, whereby the MU can detect that the SS is located in the identification information for the RU.

[94] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions.

[95] Thus, it should be understood that the aforementioned embodiments of the present invention are for purpose of illustration, and are not to be constructed as limitations of the invention. It is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

[I] A method of detecting a location of a SS(subscriber station) in a separated- type radio access station, the SS connected with the separated-type radio access station, comprising: receiving power spectrum information for an uplink frame from a remote unit; obtaining identification information for a sub-carrier corresponding to a frequency whose power value is higher than a reference value from the power spectrum information; and determining that the SS is located within a coverage area of the remote unit when it is detected with reference to mapping information for the sub-carrier allocated to the SS that the SS is mapped to the identification information.

[2] The method of claim 1, wherein the power spectrum information is measured based on an FFT analysis method.

[3] The method of claim 1, wherein the power spectrum information includes identification information for the uplink frame.

[4] The method of claim 1, wherein the power spectrum information corresponds to power spectrum above a threshold value, from which noise components are removed.

[5] The method of claim 1, wherein the step of detecting the location of the SS is carried out by a main unit.

[6] The method of claim 5, further comprising receiving identification information for the remote unit from the remote unit, wherein it is detected that the SS is located in the remote unit using the identification information for the remote unit.

[7] The method of claim 1, wherein the identification information for the sub-carrier is obtained in the main unit or remote unit.

[8] The method of claim 1, wherein the power spectrum information is measured in an uplink burst region of the uplink frame.

[9] The method of claim 1, wherein the mapping information is obtained in an uplink MAP including information for the uplink burst region used in the uplink frame by the ss.

[10] The method of claim 1, wherein the remote unit is a remote radio head or remote optic unit.

[I I] The method of claim 1, wherein the remote unit is interfaced with the main unit through a common public radio interface board.

[12] The method of claim 1, wherein the remote unit is connected with the main unit in a daisy-chain or star shape.

[13] A separated-type radio access station comprising: a remote unit for measuring power spectrum information for an uplink frame; and a main unit for obtaining mapping information between an SS (subscriber station) and a sub-carrier allocated to the SS, and to determine that the SS is located within a coverage area of the remote unit when it is detected that the SS is mapped to identification information for the sub-carrier with respect to the mapping information, wherein the identification information for the sub-carrier is identification information corresponding to a frequency whose power in the power spectrum information is higher than a reference value.

[14] The separated-type radio access station of claim 13, wherein the identification information for the sub-carrier is information obtained in a main unit.

[15] The separated-type radio access station of claim 13, wherein the identification information for the sub-carrier is information obtained in the remote unit, and transmitted to the main unit.

[16] The separated-type radio access station of claim 13, wherein the remote unit measures the power spectrum information based on an FFT analysis method.

[17] The separated-type radio access station of claim 13, wherein the power spectrum information includes identification information for the uplink frame.

[18] The separated-type radio access station of claim 13, wherein the power spectrum information corresponds to power spectrum above a threshold value, from which noise components are removed.

[19] The separated-type radio access station of claim 13, wherein the remote unit transmits identification information for the remote unit to the main unit, and the main unit detects that the SS is located in the remote unit using identification information for the remote unit.

[20] The separated-type radio access station of claim 13, wherein the remote unit measures the power spectrum information in an uplink burst duration of the uplink frame.

[21] The separated-type radio access station of claim 13, wherein the main unit obtains the mapping information in an uplink MAP including information for the uplink burst region used in the uplink frame by the SS.

[22] A main unit to detect a location of an SS(subscriber station) in a separated-type radio access station comprising: a power information analyzer for obtaining identification information for a sub- carrier corresponding to a frequency whose power value is higher than a reference value from power spectrum information of an uplink frame; and an SS location detecting unit for checking mapping information corresponding to the identification information for the sub-carrier, and to detect the location of the SS in mapping information.

[23] The main unit of claim 22, wherein the power spectrum information is transmitted from the remote unit, and the power spectrum information includes identification information for the uplink frame.

[24] The main unit of claim 22, wherein the SS location detecting unit receives identification information for the remote unit from the remote unit, and the SS location detecting unit detects that the SS located in the remote unit using identification information for the remote unit.

[25] The main unit of claim 22, wherein the mapping information is obtained in an uplink MAP including information for the uplink burst region used in the uplink frame by the SS.