KR20050014530A - Method for configurating base station transceiver system by holing digital unit of mobile communication system in common - Google Patents

Abstract

PURPOSE: A method for configuring a base station by sharing a DU(Digital Unit) of a mobile communication system is provided to magnify the resource usage rate of a base station digital part by high-capacity and concentration of a DU, and to combine the DU with at least one RF unit through one optical link, thereby reducing the cost for renting a trunk line. CONSTITUTION: A DU(400) comprises as follows. A BSC interface(403) interfaces a BSC(401). A system controller(405) processes a call by interworking with the BSC(401), and manages the operation for a BTS. Channel units(407) process CDMA baseband signals. The first optical interfaces(413) receive I/Q signals from the channel units(407) to apply a TDM process in accordance with plural RFUs(RF Units)(409,411,415) to the received signals, convert into optical signals, and send the converted optical signals to the plural RFUs(409,411,415) through an optical core. A GPS synchronizer(417) supplies a reference clock based on GPS information.

Description

A method for configuring a base station by sharing a digital unit of a mobile communication system {Method for configurating base station transceiver system by holing digital unit of mobile communication system in common}

The present invention relates to a system for sharing at least one RF unit digital unit resources in a SMART-BTS.

1 is a configuration diagram of a first embodiment showing a conventional mobile communication network. The first embodiment of the conventional mobile communication network includes a mobile switching center (MSC) 101, a base station controller (BSC) 103, a base station transceiver system (BTS) 105, and an RF repeater. 109 and optical repeater 111. The base station controller 103 is connected to the exchange 101 and to at least one base station 105, 107. In addition, the base station 105 is wirelessly transmitted and received with the RF repeater 109 or connected to the optical repeater 111 through an optical link.

The switch 101 is a device that provides a matching function with another network, a subscriber information storage and inquiry function, and a switching function for a mobile communication call. In addition, the base station controller 103 is a device that matches with at least one base station 105 or 107 and provides handoff processing function, call control function, and operation and maintenance control function between the base stations. In addition, the base station (105, 107) is a device for providing a mobile communication service to the subscriber by communicating wirelessly with the mobile terminal in the cell. The repeater is a device that provides a mobile communication service using the base station resources even in a cell coverage hole that does not reach the base station signal.

Referring to FIG. 1, a conventional mobile communication network operator installs a base station controller and a corresponding base station in an area where a mobile communication service is needed, and a repeater corresponding to each base station.

2 is a configuration diagram of a second embodiment showing a conventional mobile communication network. The conventional second embodiment mobile communication network includes a base station controller 201, digital units 203 and 205, and RF units 207, 209 and 211. The base station controller 201 is connected to at least one digital unit 203, 205 via an E1 / T1 link. The digital unit 203 is connected with the RF unit 207 via an optical link, and the digital unit 205 is coupled with at least one RF unit 209, 211 via an optical link. In addition, the digital unit 220 includes a digital part 221, an RF modulator 223, an A / D converter 225, and an optical matching unit 227. In addition, the RF unit 230 includes an optical matching unit 231, a D / A converter 233, an RF modulator 235, and an RF part 237.

Referring to FIG. 2, in the conventional mobile communication network, the base station is separated into a digital unit and an RF unit, and the digital unit and the RF unit are connected through an optical link. In the second exemplary embodiment of the present invention, the RF modulator 223 modulates an intermediate frequency (IF) signal into a radio frequency (RF) signal in order to transmit several signals in one optical link in a mobile communication network. Thereafter, the A / D converter 225 modulates the analog signal into a digital signal, and the modulated digital signal is transmitted to the RFU through an optical link. Modulating an analog signal into a digital signal in the above process may generate a quantization error and thus degrade the quality of a mobile communication service. In addition, the RF unit in the mobile communication network of the conventional second embodiment operates only as an independent cell, and does not have an automatic conversion function to an independent cell or a repeater in conjunction with the number of mobile communication calls in the cell.

It is an object of the present invention to provide a system that allows at least one RF unit to share resources of a digital unit using a time division scheme in SMART-BTS.

Another object of the present invention is to provide a function in which a failure is not transmitted to a lower RF unit even when a failure occurs in the upper RF unit.

Another object of the present invention is that the digital unit allocates a unique PN code or a duplicate PN code to at least one RF unit, so that the RF unit assigned the unique PN code functions as an independent cell and allocates a duplicate PN code. The received RF unit is to act as a repeater, to provide a function to optimize the wireless network.

It is still another object of the present invention to provide an optical matching unit for time division multiplexing an I / Q signal received from a channel unit by at least one RF unit, pre-op converting a time division multiplexed signal, and converting an all-optical converted optical signal to an optical core. By using to transmit to at least one RF unit to provide a function to prevent the quantization error according to the prior art.

1 is a configuration diagram of a first embodiment showing a conventional mobile communication network.

2 is a configuration diagram of a second embodiment showing a conventional mobile communication network.

3 is a diagram schematically illustrating a wireless network configuration of SMART-BTS in which at least one RF unit can share resources of a digital unit using a time division scheme according to an embodiment of the present invention.

4 is a diagram schematically showing a configuration of a digital unit according to an embodiment of the present invention.

5 is a view schematically showing the configuration of the RF unit according to an embodiment of the present invention.

6A schematically illustrates a configuration in which a digital unit is connected with at least one RF unit according to an exemplary embodiment of the present invention.

6b schematically illustrates a configuration in which a digital unit is combined with at least one RF unit in series form via an optical link according to another preferred embodiment of the present invention.

7 is a schematic view showing a configuration in which at least one RF unit is connected in series according to an embodiment of the present invention.

8 is a flowchart schematically illustrating a process in which at least one RF unit is set to an independent cell shape or a repeater shape according to an exemplary embodiment of the present invention.

9 is a diagram illustrating that a digital unit includes operation management information for at least one RF unit, according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

400: digital unit 409: RF unit

405: system control unit 407: channel unit

413: optical matching unit 417: GPS synchronization unit

In order to achieve the above object, according to an aspect of the present invention, in a mobile communication system sharing a resource of a digital unit (DU), Mobile Switching Center (MSC), the base station coupled to the switch A base station controller (BSC), which is coupled to the base station controller via a dedicated line, and divides I / Q (Inphase / Quadrature) signals by a plurality of RFUs (Time Division Mutiplex (TDM)). After all-optical conversion, the digital unit for transmitting the all-optical conversion optical signal to the plurality of RF units through the optical core and the all-optical conversion optical signal from the digital unit after receiving the optical signal as an I / Q signal After the photoelectric conversion, it is possible to provide a mobile communication system including a plurality of RF units which are converted to RF (Radio Frequency) signal and transmitted to the antenna.

In a preferred embodiment, the digital unit is located in an exchange office, and the plurality of RF units are located in a cell site. The RF unit may extract time slot information corresponding to the predetermined RF unit included in the optical signal, and photoelectric convert the optical signal into the I / Q signal according to the time slot information. do. The RF unit may convert the photoelectrically converted I / Q signal into an intermediate frequency (IF) signal and then convert the IF signal into the RF signal using a preset carrier frequency. In addition, when the RF unit detects an internal malfunction, the RF unit may transmit the I / Q signal to another RF unit connected to the RF unit.

According to another aspect of the present invention, in the digital unit (DU) that is matched to a plurality of RF units (Radio Frequency Unit; RFU), BSC matching unit for matching the base station controller (BSC), A system controller which processes a call in conjunction with the base station controller and manages an operation for a base station transceiver system (BTS), a channel unit that processes a code division multiple access (CDMA) baseband signal, and I from the channel unit. Receives a / Q (Inphase / Quadrature) signal, performs time division multiplexing (TDM) on each of the plurality of RF units, and performs all-optical conversion, and then transmits an all-optical converted optical signal to the plurality of RF units through an optical core. A GPS synchronization unit providing a reference clock to the BSC matching unit, the system control unit, the channel unit, and the optical matching unit based on the first optical matching unit and the Global Position System (GPS) information. A digital unit which can be provided.

In a preferred embodiment, the RF unit, after receiving the all-optical converted optical signal, extracts the time slot information corresponding to the predetermined RF unit included in the optical signal, I / I corresponding to the time slot information A second optical matching unit that photoelectrically converts a Q signal from the optical signal, receives the I / Q signal from the second optical matching unit, converts the I / Q signal into an IF (Intermediate Frequency) signal, and then uses a preset carrier frequency. And a transceiver unit for converting the IF signal into a radio frequency (RF) signal and a duplexer for transmitting the RF signal to an antenna. In addition, when the second optical matching unit detects a malfunction of at least one of the transceiver unit and the duplexer, the second optical matching unit transfers the I / Q signal to another RF unit connected to the RF unit. The system controller may allocate independent channel resources to the specific RF unit when the specific RF unit is used as an independent cell. The system control unit may allocate channel resources corresponding to neighboring RF units to the specific RF unit when the specific RF unit is used as a repeater. In the case where a specific RF unit is used as a repeater, the digital unit allocates a redundant PN (Pseudo Noise) code to the specific RF unit and the RF unit adjacent to the specific RF unit.

According to another aspect of the present invention, in a method for configuring a base station transceiver system (BTS) in the digital unit (DU), to share resources to a plurality of Radio Frequency Unit (RFU), Receiving a traffic signal from a base station controller (BSC) coupled to a dedicated line; processing the received traffic signal by code division multiple access (CDMA) baseband signal; and as a result of the signal processing, I / Q ( Time division multiplexing (TDM) an Inphase / Quadrature signal by a plurality of units, totally converting the time division multiplexed I / Q signal, and converting the all-optically converted optical signal through an optical core Provided is a method for configuring a base station including transmitting to an RF unit.

In a preferred embodiment, the RF unit extracts the time slot information corresponding to the preset RF unit included in the optical signal after receiving the all-optical converted optical signal, and the I corresponding to the time slot information. Photoelectric conversion of the / Q signal from the optical signal, and converting the photoelectrically converted I / Q signal into an intermediate frequency (IF) signal, and then converting the IF signal into a radio frequency (RF) signal using a preset carrier frequency. It converts and transmits to an antenna.

Next, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 schematically illustrates a wireless network configuration of SMART-BTS in which at least one RF unit may share resources of a digital unit using a time division scheme according to an embodiment of the present invention. The SMART-BTS (Smart Base Station Transceiver System) divides a conventional base station into a digital unit (DU) and an RF unit (Radio Frequency Unit (RFU)).

Referring to FIG. 3, the first digital unit 301 is connected with the first base station controller 303 and coupled with at least one RF unit 321, 323, 325, 327, 331. The RF unit 327 may be connected to the repeater 329. In addition, the first base station controller 303 is connected to the first digital unit 301, the second digital unit 337, and the ATM router 307. The second digital unit 337 is connected with the first base station controller 303 and is coupled with at least one RF unit 333, 335, 339. The ATM router 307 is connected to a first base station controller 303, a base station manager (BSM) 305, an exchange 309, a packet data serving node (PDSN) 311, and a second base station controller 341. do. The second base station controller 341 is connected to the ATM router 307, the third digital unit 343. The third digital unit 343 is connected to the RF unit 345.

The first digital unit 301 serves to allow at least one RF unit 321, 323, 325, 327 to share digital unit resources by a time division scheme according to a preferred embodiment of the present invention. To this end, the first digital unit 301 is wire-matched with at least one RF unit 321, 323, 325, 327 through an optical core, and performs multiplexing and demultiplexing using an optical transmission scheme. In addition, the digital units 301, 337, and 343 may perform a cdma-2000 1x call processing function. That is, the digital units 301, 337, and 343 support calling and terminating functions of the mobile terminal, and support call setup and release by the base station higher and call setup and release by the mobile terminal. In addition, the digital units 301, 337, and 343 support a handoff processing function by voice type (voice and high speed data calls). In addition, the digital units 301, 337, and 343 may include an access handoff function, an enhanced soft handoff function, an enhanced hard handoff function, an inter-BTS, an inter-BSC, an inter-MSC soft handoff function, and an inter- Generation handoff is supported. In addition, the digital units 301, 337, and 343 support a location registration function. In addition, the digital units 301, 337, and 343 may perform a cdma-2000 1xEV-DO call processing function. That is, the digital units 301, 337, and 343 support a data outgoing call setup (New Session, Pre-existing Session) function, a data incoming call setup (New Session, Pre-existing Session) function, and a data call release function. . In addition, the digital units 301, 337, and 343 support Dormant setting / release function by a terminal and Dormant setting / release function by a network. In addition, the digital units 301, 337, and 343 have an Active / Dormant / Idle handoff function between sectors of the same base station, an Active / Dormant / Idle handoff function between the same base station controller and another base station, different PCFs and different base stations. Active / Dormant handoff between controllers, Dormant handoff between the same PDSN and another PCF, and Dormant handoff between different PDSNs are supported. In addition, the main processes and devices of the digital units 301, 337, and 343 are duplicated, and when a process or device fails, the process is automatically switched to the duplicated process or device. In addition, the digital units 301, 337, and 343 support radio resource management functions such as radio channel setting and release and overload control.

The RF units 321, 323, 325, 327, 331, 333, 335, 339, and 345 convert the CDMA modulated digital signal into an RF signal in the digital units 301, 337, and 343, and are received from the subscriber station. It converts an RF signal into a digital signal and optically transmits the digital signal to the digital units 301, 337, and 343. In addition, the at least one RF unit 321, 323, 325, and 327 share a resource of the first digital unit 301 by a time division method, and the first digital unit 301 is at least one RF unit 321. It can serve as a repeater by assigning the same PN (Pseudo Noise) code to 323, 325. In addition, the performance and characteristics of the RF transceiver of the RF units 321, 323, 325, 327, 331, 333, 335, 339, and 345 are cdma2000 1x and 1xEV-DO's "Minimum Performance Standard for cdma2000 Spread Spectrum Base stations" standard. Must satisfy In addition, the RF unit 321, 323, 325, 327, 331, 333, 335, 339, 345 is a transmission frequency operating range of 1840MHz to 1860MHz, a reception frequency operating range of 1750MHz to 1770MHz. In addition, the transmission and reception bands of the duplexers in the RF units 321, 323, 325, 327, 331, 333, 335, 339 and 345 are 1840 MHz to 1860 MHz and 1750 MHz to 1770 MHz. In addition, the RF units 321, 323, 325, 327, 331, 333, 335, 339, and 345 share the antenna with the IS-95A / B and CDMA2000-1x systems to minimize losses. Provides a function of bypassing the duplexers of the units 321, 323, 325, 327, 331, 333, 335, 339, and 345. In addition, the RF units 321, 323, 325, 327, 331, 333, 335, 339, and 345 independently provide two receive paths per sector for receive diversity. In addition, the RF units 321, 323, 325, 327, 331, 333, 335, 339, and 345 may include a transceiver processor or a transceiver to adjust an error between the RF unit expected output value and the RF unit actual output value adjusted by the instruction. The transceiver input front end includes an adjustment terminal for adjusting the intermediate frequency (IF) output. The adjustment terminal can be adjusted using a simple tool or the like from the outside without board detachment. The RF units 321, 323, 325, 327, 331, 333, 335, 339, and 345 may measure a base station transmit / receive power measurement function, a VSWR (Voltage Standing Wave Ratio) measurement function of a transmit / receive path, and a TPTL (Transceiver Power Tracking Loop). It includes a base station test unit (BTU) function that can provide a transmission power correction function. The RF units 321, 323, 325, 327, 331, 333, 335, 339, and 345 may provide outgoing and incoming call test functions. In addition, the RF units 321, 323, 325, 327, 331, 333, 335, 339, and 345 may provide a function of reporting status information on the BTU test module. The state information includes a failure report, a terminal state during test call operation, and the like. In addition, the RF units 321, 323, 325, 327, 331, 333, 335, 339, and 345 provide statistical processing functions. The statistical processing function is a function to allow the operator to periodically check the statistical data for the item measured by the base station. In addition, the RF units 321, 323, 325, 327, 331, 333, 335, 339, and 345 are provided with sufficient transmit / receive test ports for main signal testing of the RF transceiver.

Referring to the above configuration, a method of sharing at least one RF unit digital unit resources by a time division scheme in the SMART-BTS according to the present invention will be described as follows.

The first digital unit 301 is an optical core for performing at least one RF unit 321, 323, 325, and 327 to share digital unit resources by a time division scheme according to a preferred embodiment of the present invention. The wire-line matching with the at least one RF unit is performed using A, and multiplexing and demultiplexing are performed using an optical transmission method. In addition, the first digital unit 301 is configured for each of at least one RF unit 321, 323, 325, and 327 of the I / Q (Inphase / Quadrature) signal input to the optical matching unit included in the first digital unit. Time division multiplexing. Thereafter, the first digital unit 301 omits the time division multiplexed signal and transmits the all-optical converted signal to at least one RF unit 321, 323, 325, 327 using one optical core. At least one RF unit 321, 323, 325, and 327 may share resources of the first digital unit 301 such as a call processor, a GPS receiver, and channel resources. In addition, the first digital unit 301 enables shape setting and modification of the RF units 321, 323, and 325. That is, the first digital unit 301 may remotely set the RF units 321, 323, and 325 into independent cell or repeater shapes according to cell site subscriber distribution. When the RF units 321, 323, and 325 are set in the shape of a repeater, the first digital unit 301 shares the channel resources and the RF resources of the adjacent cell type RF units adjacent to the RF units 321, 323, and 325. Do it. In addition, the first digital unit 301 serves as a conventional repeater by the RF unit 321, 323, 325 by assigning a redundant PN code to at least one RF unit 321, 323, 325. Do it. In addition, when the subscriber station is increased in the cell site using the repeater-shaped RF units 321, 323, and 325, the first digital unit 301 may be the RF units 321, 323, and 325 to which duplicate PN codes are assigned. ) By assigning an independent PN code in software) provides the function that the repeater-shaped RF unit (321, 323, 325) can operate as an independent cell. In addition, the first digital unit 301 includes more CDMA channel banks than conventional ones to support at least one RF unit 321, 323, 325, and 327.

4 is a diagram schematically illustrating a configuration of a digital unit according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the digital unit 400 includes a BSC matching unit 403, a system control unit 405, a channel unit 407, an optical matching unit 413, and a GPS synchronizer 417. The digital unit 400 is coupled to the base station controller 401 via an E1 / T1 link and coupled to at least one RF unit 409, 411, 415 via an optical link.

The BSC matching unit 403 may transmit and receive with the system control unit 405 through a first control signal 421, and transmit and receive with the channel unit 407 through a first traffic signal 427. It may be transmitted and received with the GPS synchronizer 417 through a network synchronizer signal 429. In addition, the BSC matching unit 403 is connected to the base station controller and performs a function of matching the digital unit 400 and the base station controller 401.

The system control unit 405 may transmit and receive with the BSC matching unit 403 through a first control signal 421, and transmit and receive with the channel unit 407 through a second control signal 423. And it can be transmitted and received with the GPS synchronizer 417 through a network synchronizer signal. In addition, the system controller 405 interworks with a base station controller to perform a call processing function and an operation management function for a BTS.

The channel unit 407 may transmit and receive with the system control unit 405 through a second control signal 423, and transmit and receive with the BSC matching unit 403 through a first traffic signal 427. It may be able to transmit and receive with the optical matching unit 413 through a second traffic signal 425, and may be transmitted and received with the GPS synchronizer 417 through a network synchronizer signal 431. . In addition, the channel unit 407 performs a CDMA baseband signal processing function.

The optical matching unit 413 receives an I / Q signal from the channel unit 407 and performs time division multiplexing on at least one RF unit, and performs an optical conversion of the time division multiplexed signal. In addition, the optical matching unit 413 transmits the all-optical converted optical signal to at least one RF unit using an optical core.

In addition, the GPS synchronizer 417 receives time information and position information from the GPS and transmits a base station reference clock to the BSC matching unit 403, the system control unit 405, the channel unit 407, and the optical matching unit 413. do.

5 is a view schematically showing the configuration of the RF unit according to an embodiment of the present invention.

Referring to FIG. 5, the RF unit 500 includes an optical matching unit 503, a transceiver unit 505, a high power amplifier 507, a low noise amplifier 509, and a duplexer 511. The RF unit 500 is connected to the digital unit 501 through an optical link and is connected to another RF unit 513 through an optical link.

The transceiver unit 505 converts the digital I / Q signal received from the digital unit 501 into an IF signal and converts it into an RF signal using a preset carrier frequency. In addition, the transceiver unit 505 converts an RF signal received from the terminal through an antenna into an IF signal, and converts the IF signal into a digital I / Q signal.

4 and 5, the process of processing data in the direction of the terminal from the base station will be described.

The optical matching unit 413 receives the second traffic signal 425 from the channel unit 407. The second traffic signal becomes an I / Q signal. The optical matching unit 413 time-division multiplexes the received I / Q signal for each RF unit, all-optically converts the time-division multiplexed signal, and transmits the all-optically converted optical signal to at least one RF unit using an optical core. do. Thus, the at least one RF unit may share digital unit resources such as a call processing processor, a GPS receiver, channel resources, and the like. By sharing digital unit resources with at least one RF unit, the operator can reduce the overall equipment investment. In addition, the operator can reduce the area and the base station weight required for the base station installation by placing the centralized digital unit in the switching center with the base station controller and at least one RF unit in the cell site. In addition, one digital unit includes a larger number of CDMA channel banks than conventional base stations to support at least one RF unit.

In the prior art, in order to transmit a signal for each RF unit using one optical core, the digital unit modulates the digital I / Q signal received from the channel unit into an RF signal and then converts the analog signal into a digital signal. Thereafter, the digital unit totally converts the converted digital signal and transmits the all-light converted signal. According to the conventional technology, a quantization error occurs in the process of converting an analog signal into a digital signal, thereby degrading the quality of a mobile communication service. However, according to the present invention, the optical matching unit 413 time-division multiplexes the received I / Q signal by at least one RF unit, and performs an optical photoconversion of the time-division multiplexed signal, and converts the all-optical signal into an optical core. To transmit to at least one RF unit. Accordingly, since the process of converting an analog signal to a digital signal according to the prior art is omitted, a quantization error does not occur, thereby reducing the problem of deterioration of the quality of a mobile communication service.

The optical signal transmitted from the digital unit 501 is transmitted through the optical core and received by the RF unit 500. The optical matching unit 503 photoelectrically converts the received optical signal. In addition, the optical matching unit 503 extracts predetermined time slot information from the photoelectrically converted signal and transmits the corresponding signal to the transceiver unit 505, and the remaining signals are all-optical converted again to the next stage of the RF unit. To 513. The transceiver unit 505 converts the received digital I / Q signal into an IF signal, converts the IF signal into an RF signal using a preset carrier frequency, and then converts the RF signal into a high output amplifier 507. send. In addition, the high power amplifier 507 high output amplifies the received RF signal. The high power amplified signal is radiated through an antenna.

Referring to Figures 4 and 5, the process of processing data in the direction of the base station in the terminal will be described as follows.

The signal received from the terminal through the antenna is amplified by the low noise amplifier 509, and the high frequency component and the spurious component of the received signal are attenuated. In addition, the transceiver unit 505 converts the RF signal received from the low noise amplifier 509 into an IF signal, and converts the IF signal into an I / Q signal. The converted I / Q signals are divided for each RF unit, and then time-division multiplexed together with the signals of the previous stages of the RF units. In addition, the time division multiplexed signal is optically converted and optically transmitted to the digital unit. The optical signal transmitted through the optical core is photoelectrically converted in the digital unit and then transmitted to at least one channel portion corresponding to the at least one RF unit. The at least one channel unit transmits the signal to the base station controller after the CDMA baseband signal processing.

6A is a diagram schematically illustrating a configuration in which a digital unit is connected to at least one RF unit according to an exemplary embodiment of the present invention.

Referring to FIG. 6A, the digital unit 603 is connected with at least one RF unit 601, 605, 607 through an optical link. The digital unit 603 may connect up to three branches.

6B schematically illustrates a configuration in which a digital unit 651 is coupled with at least one RF unit 653, 657, 659 in series form over an optical link in accordance with another preferred embodiment of the present invention.

Referring to FIG. 6B, the digital unit 651 is coupled with at least one RF unit 653, 657, 659 in series form over an optical link. The digital unit 651 may be connected to at least four RF units. In addition, the digital unit provides a cell site resource sharing function in which at least one RF unit can share channel resources of the same cell site.

7 is a view schematically showing a configuration in which at least one RF unit is connected in series according to an embodiment of the present invention.

Referring to FIG. 7, the RF unit includes an optical matching unit 703, a transceiver unit 705, a high power amplifier 707, a low noise amplifier 709, and a duplexer 711. When the remaining portion 700 except the light matching unit 703 inside the RF unit is in an abnormal state, the optical matching unit 703 bypasses the optical signal received from the digital unit to bypass the next stage of RF. Send to the unit. Thus, even if at least one RF unit is in an abnormal state, other RF units connected in series are not affected.

8 is a flowchart schematically illustrating a process in which at least one RF unit is set to an independent cell shape or a repeater shape according to an exemplary embodiment of the present invention.

Referring to FIG. 8, at least one RF unit may be set to an independent cell or a repeater shape according to the subscriber distribution of the cell site. To this end, the system control unit of the digital unit compares the number of subscriber stations in the conventional cell site with the number of subscriber stations in the current cell site (step 801). If the result of the comparison is that the number of subscriber stations in the conventional cell site is less than or equal to the number of subscribers in the current cell site (step 803), the system control unit of the digital unit allocates independent channel resources and RF resources to the at least one RF unit. Assign (step 805). Thus, the at least one RF unit performs the RF unit function in the conventional base station in the form of an independent cell (step 807). Further, if the comparison result is that the number of subscriber stations in the conventional cell site is larger than the number of subscribers in the current cell site (step 811), the system control unit of the digital unit is configured to determine whether the independent cell-shaped RF unit adjacent to the at least one RF unit. Allocate channel resources and RF resources. The at least one RF unit may be allocated channel resources and RF resources of the adjacent independent cell shape RF unit, thereby sharing channel resources and RF resources with the adjacent independent cell shape RF unit (step 813). Thus, the at least one RF unit performs the function of a conventional repeater in the shape of a repeater (step 815).

When the at least one RF unit is set in the shape of a repeater (851), the system control unit of the digital unit compares the number of subscriber stations to the current cell site and the number of subscriber stations to the current cell site (step 821). As a result of the comparison, if the number of subscriber stations in the conventional cell site is smaller than the number of subscribers in the current cell site (step 823), the system control unit of the digital unit allocates independent channel resources and RF resources to the RF unit set to the repeater shape. Assign. Therefore, when the number of subscriber stations of the cell site corresponding to the RF unit set in the repeater shape increases, the system controller of the digital unit may change the RF unit set in the repeater shape into an independent cell shape.

In addition, the digital unit allocates a channel resource and a unique PN code for each of the at least one RF unit or allocates a redundant PN code. When a unique PN code is assigned to at least one RF unit, the RF unit may operate as an independent base station and has a general base station capacity. However, when a redundant PN code is assigned to at least one RF unit, the RF unit includes a relay function, shares base station capacity with adjacent independent cell-shaped RF units, and serves to expand base station service coverage. In addition, the redundant PN code allocated repeater shape RF unit may be changed into an independent cell shape by receiving an independent PN code by software.

9 is a diagram illustrating that a digital unit includes operation management information for at least one RF unit, according to an embodiment of the present invention.

Referring to FIG. 9, the digital unit of the switching center may perform initialization, failure detection, shape setting, and change operation for the RF unit. Operation management of the existing repeater was difficult to manage the repeater operation because it consists of a separate operation management system and the base station operation management system. However, according to the present invention, the digital unit can collect the operation management information for the RF unit, such as initialization, failure detection, configuration and change of the RF unit, and transmits it to the base station controller, so that operation management can be performed like an existing base station.

The present invention is not limited to the above embodiments, and many variations are possible by those skilled in the art within the spirit of the present invention.

According to the present invention, a method and system for allowing at least one RF unit to share resources of a digital unit using a time division scheme in SMART-BTS can be provided. The operator can maximize the resource utilization of the base station digital part by increasing and centralizing the digital unit, and reduce the relay line rental cost by combining the digital unit with at least one RF unit through one optical link. That is, by connecting the RF units located in close proximity through one optical core, it is possible to reduce the relay line rental cost than using the conventional E1 leased line for each base station.

In addition, the operator can reduce the area and the base station weight required for the base station installation by placing the centralized digital unit in the switching center with the base station controller and at least one RF unit in the cell site.

In addition, according to the present invention, even when a failure occurs in the upper RF unit, it is possible to provide a function to prevent the failure from being transmitted to the lower RF unit.

In addition, according to the present invention, the digital unit allocates a unique PN code or a duplicate PN code to at least one RF unit, so that the RF unit to which the unique PN code is assigned operates as a base station which is an independent cell, and receives the duplicate PN code. The unit may serve as a repeater to provide a function of optimizing the wireless network.

In addition, according to the present invention, since a process of converting an analog signal to a digital signal according to the prior art is omitted, and a quantization error does not occur, it is possible to solve the problem of deterioration of the quality of a mobile communication service.

In addition, according to the present invention, by connecting at least one RF unit to one digital unit, the base station call processing capacity can be divided into a maximum of six sectors, compared to the conventional one which can be divided into three sectors per base station. It is possible to increase significantly.

Claims (13)

In the mobile communication system for sharing the resources of the digital unit (DU), Mobile Switching Center (MSC); A base station controller (BSC) coupled to the exchange; Coupled to the base station controller through a dedicated line, an I / Q (Inphase / Quadrature) signal is divided into a plurality of RF unit (Radio Ferquency Unit (RF)) by time division multiplexing (Time division Mutiplex (TDM)), and then all-optical conversion A digital unit for transmitting an optical signal to the plurality of RF units through an optical core; And A plurality of RF units for receiving an optical signal converted from the digital unit, photoelectrically converting the optical signal into an I / Q signal, and then converting the optical signal into an RF (Radio Frequency) signal and transmitting the result to an antenna Mobile communication system comprising a. The method of claim 1, Wherein the digital unit is located at an exchange station, and the plurality of RF units are located at a cell site. Mobile communication system, characterized in that. The method of claim 1, The RF unit extracts time slot information corresponding to the predetermined RF unit included in the optical signal, and photoelectric converts the optical signal into the I / Q signal according to the time slot information. Mobile communication system, characterized in that. The method of claim 1, The RF unit converts the photoelectrically converted I / Q signal into an intermediate frequency (IF) signal, and then converts the IF signal into the RF signal using a preset carrier frequency. Mobile communication system, characterized in that. The method of claim 1, When the RF unit detects an internal malfunction, the RF unit transmits the I / Q signal to another RF unit connected to the RF unit. Mobile communication system, characterized in that. In a digital unit (DU) matched to a plurality of radio frequency units (RFU), A BSC matching unit for matching a base station controller (BSC); A system controller which processes a call in association with the base station controller and manages operation of a base station transceiver system (BTS); A channel unit for processing a code division multiple access (CDMA) baseband signal; Receives an I / Q (Inphase / Quadrature) signal from the channel unit, performs time division multiplexing (TDM) on each of the plurality of RF units, and then converts the all-optically converted optical signal through the optical core. A first optical matching portion transmitting to the RF unit of the; And GPS synchronization unit for providing a reference clock to the BSC matching unit, system control unit, channel unit and optical matching unit based on global position system (GPS) information Digital unit comprising a. The method of claim 6, The RF unit After receiving the all-optical converted optical signal, time slot information corresponding to the preset RF unit included in the optical signal is extracted, and the I / Q signal corresponding to the time slot information is photoelectrically converted from the optical signal. A second optical matching unit; A transceiver unit for receiving the I / Q signal from the second optical matching unit, converting the IF signal into an intermediate frequency (IF) signal, and converting the IF signal into a radio frequency (RF) signal using a preset carrier frequency; And A duplexer for transmitting the RF signal to an antenna Digital unit comprising a. The method of claim 7, wherein Transmitting the I / Q signal to another RF unit connected to the RF unit when the second optical matching unit detects a malfunction of at least one of the transceiver unit and the duplexer. Digital unit characterized in that. The method of claim 6, The system control unit Allocating independent channel resources to the specific RF unit when the specific RF unit is used as an independent cell; Digital unit characterized in that. The method of claim 6, The system control unit In the case where a specific RF unit is used as a relay, allocating a channel resource corresponding to an adjacent RF unit to the specific RF unit Digital unit characterized in that. The method of claim 6, When a specific RF unit is used as a repeater, the digital unit assigns duplicate PN (Pseudo Noise) codes to the specific RF unit and the RF unit adjacent to the specific RF unit Digital unit characterized in that. In a method for configuring a base station transceiver system (BTS) to share resources in a digital unit (DU), a plurality of radio frequency unit (RFU), Receiving a traffic signal from a base station controller (BSC) coupled to a dedicated line; Processing the received traffic signal by code division multiple access (CDMA) baseband signal; As a result of the signal processing, time division multiplexing (IDM) an I / Q (Inphase / Quadrature) signal for each of a plurality of units; Optically converting the time division multiplexed I / Q signal; And Transmitting the all-optical converted optical signal to the plurality of RF units through an optical core Base station configuration method comprising a. The method of claim 12, The RF unit After receiving the all-optical converted optical signal, time slot information corresponding to the predetermined RF unit included in the optical signal is extracted, and the I / Q signal corresponding to the time slot information is converted from the optical signal. And converting the photoelectrically converted I / Q signal into an intermediate frequency (IF) signal, and then converting the IF signal into a radio frequency (RF) signal using a preset carrier frequency and transmitting the same to an antenna. Base station configuration method characterized in that.