KR101024574B1 - Base Station and Base Station System - Google Patents

Abstract

A base station according to an aspect of the present invention capable of performing all of the functions performed by a general base station while reducing the size of a base station includes an RF band band-passed transmission of an uplink signal or a band-filtered transmission of a downlink signal. A front end unit; A transmission / reception unit configured to low-noise amplify the band-filtered uplink signal and frequency down-convert to output a frequency down-converted signal, or adjust a signal level with respect to a frequency up-converted signal to output the downlink signal; And inversely modulate the baseband uplink signal with respect to the frequency down-converted signal and convert the baseband uplink signal into an uplink IP packet to transmit to an ACR (Access Control Router), or receive the downlink IP packet transmitted from the ACR and change the downlink IP packet. And a main unit for modulating the baseband downlink signal with respect to the frequency up-converted signal, wherein the main unit supports an interfacing function with the ACR and a scalable interface function in a daisy chain manner. part; And a clock synchronizer configured to generate a clock signal using a GPS signal or a synchronization message and provide the generated clock signal.

Base station, GPS, sharing, sync

Description

Base station and base station system using same {Base Station and Base Station System}

The present invention relates to a communication device, and more particularly, to a base station and a base station system using the same.

In general, a base station (Radio Access Station) (RAS), which is one of communication devices included in a wireless communication system, transmits related signals and uplink traffic data transmitted wirelessly from a mobile station (MS) as shown in FIG. It delivers to a network through an access control router (ACR) and, conversely, receives a related signal and downlink traffic data transmitted from the network through a control station and wirelessly provides the terminal.

That is, in a wireless communication system, a base station may interface with a control station, process a base band signal, process a radio frequency (RF) signal, and interface with a terminal. A communication device that performs the.

The base station in charge of the above-described functions may have various sizes according to the size of the service area to be covered by the base station. In recent years, the base station covers a shaded area such as the inside or the basement of a building or a number of subscribers covered by a general base station. There is a growing interest in small base stations that can cover an area with a relatively small number of subscribers.

That is, the demand for a small base station that can cover a smaller service area than that of a general base station is increasing.

In the case of such a small base station, since all the above-described functions performed by the general base station must be performed, hardware components capable of performing the above-described functions must be included in a single device.

However, since a small base station has to be relatively small in size and light in weight compared with a general base station, it is not easy to implement a base station that may include all hardware components capable of implementing each of the above-described functions.

Disclosure of Invention The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a base station capable of performing all functions performed by a general base station while reducing the size of the base station and a base station system using the same.

Another object of the present invention is to provide a base station capable of sharing a GPS signal between each base station and a base station system using the same.

In addition, another object of the present invention is to provide a base station that can be easily expanded according to capacity and installation environment and a base station system using the same.

According to an aspect of the present invention, there is provided a base station including: an RF front end unit for band-filtering and transmitting an uplink signal or for performing band-filtering a downlink signal; A transmission / reception unit configured to low-noise amplify the band-filtered uplink signal and frequency down-convert to output a frequency down-converted signal, or adjust a signal level with respect to a frequency up-converted signal to output the downlink signal; And inversely modulate the baseband uplink signal with respect to the frequency down-converted signal and convert the baseband uplink signal into an uplink IP packet to transmit to an ACR (Access Control Router), or receive the downlink IP packet transmitted from the ACR and change the downlink IP packet. And a main unit for modulating the baseband downlink signal with respect to the frequency up-converted signal, wherein the main unit supports an interfacing function with the ACR and an interfacing function that can be extended in a daisy chain manner. An interface unit; And a clock synchronizer configured to generate a clock signal using a GPS signal or a synchronization message and provide the generated clock signal.

A base station system according to another aspect of the present invention for achieving the above object, the first 1PPS signal, the first clock signal, and the synchronization message for the synchronization setting with the slave base station using the GPS signal received from the GPS antenna directly A master base station for generating a synchronization message and transmitting the synchronization message to a slave base station; And at least one slave base station generating a second 1PPS signal and a second clock signal by using a synchronization message transmitted from the master base station.

According to the present invention, there are provided units capable of performing an interworking function, a baseband signal processing function, an interface function, an RF signal processing function, and an RF signal interface functions in an air section with a terminal performed by a general base station. By implementing in a single device, the size of the base station can be reduced, so that the base station can be freely installed without being restricted by the external environment.

In addition, the present invention has an effect that the manufacturing cost of the base station can be lowered by including the GPS antenna and the GPS receiving module only in the master base station of each base station and by configuring the base stations to share the GPS signal of the master base station.

In addition, since the present invention performs an interfacing function or network synchronization with a control station using a data chain, not only 1FA / Omni service but also three base stations can be extended and provided up to 1FA / 3Secotr service according to capacity and installation environment. It can be effective.

In addition, the present invention can be replaced by a unit rather than a unit, and easy to maintain, and it is possible to operate at low power consumption by avoiding redundant design of each function when implementing a base station.

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

2 is a schematic block diagram of a base station according to an embodiment of the present invention. The base station according to the present invention is a small base station that can cover a relatively small number of subscribers as compared to the number of subscribers covered by a general base station or a cover of a shadow area, such as the interior or basement of a building, one base station The 1FA (Frequency Assignment) / 1 sector (Sector) function can perform, and can support the same subscriber capacity and performance as the 1FA / 1Sector capacity supported by a large base station performing a 3FA / 3 Sector function.

Specifically, in the high-capacity base station of the general 3FA / 3Sector, the network interface processing unit (one unit) and the base station management processing unit (one unit) each perform its function in one representative processor, and the MAC function of 802.16d / e. The processing unit (up to nine units) performs its function on different hardware processors configured for each FA / Sector.

In contrast, the small base station according to the present invention can perform three functions such as network interface processing, base station management processing, and MAC function processing of 802.16d / e in one processor, and has a memory storage function for history storage. In order to reduce the waste of memory by integrating the memory and to modularize the software according to the characteristics of each function, each function can use a separate memory management module to efficiently share and use the memory.

In addition, the small base station according to the present invention integrates the lower modules that are commonly performed for each function, and at the same time distinguishes modules that need to be performed and modules that do not, and sets priorities for each task. By minimizing the weight of the hardware, and by dividing the online command required by the operator into the operation mode, the hidden mode, and the shell mode, it minimizes the weight of the load that requires the standby operation. Allow it to run normally.

In particular, in the case of the present invention, each base station performing the 1FA / 1 sector function shares a GPS signal with each other to synchronize synchronization with each base station.

The base station 200 includes a main unit 210, a transceiver unit 220, an RF front end unit 230, and an amplification unit 240 as shown.

Main unit 210 is largely WiMAX's PHY / MAC modem function, 1FA function, base station overall system operation function, routing interface function to support R6 interface, interface interface between control station (ACR) and base station, Fast Ethernet or Gigabit It performs Ethernet interface function, IP-based interface function with internal or external base station, and detects the failure and alarm status of each unit or module included in the base station by detecting the operation status related to the operation of the base station. Hereinafter, the main unit 210 will be described in detail with reference to FIG. 3.

3 is a schematic block diagram of a main unit according to an embodiment of the present invention. As shown, the main unit 210 includes a main processor 300, an interface 310, a frequency converter 320, a physical layer processor 330, and a clock synchronizer 340.

The main processor 300 is responsible for the overall system operation of the base station, and performs a call processing function for access of the terminal, where the call processing function is controlled when the terminal attempts to access a wireless communication system (not shown). It refers to a function of connecting the terminal to the wireless communication system after checking the authority of the terminal in conjunction with a wireless communication system or a core network (not shown) through a signal.

In addition, the main processor 300 performs communication for each unit 210 to 240 included in the base station 200, and each unit 210 to 240 or each unit 210 to 240 included in the base station 200. ) Controls the components included in the), and collects the final alarm generated by the base station 200 and reports it to the element management server (EMS).

In addition, the main processing unit 300 supports signal processing functions related to various MAC layers defined in IEEE 802.16d / e. For example, the main processing unit 300 may include an automatic repeat request (ARQ) and a complex automatic function. It can support Hybrid Automatic Repeat Request (HARQ), Adaptive Modulation and Coding, and provide sampling frequency (e.g., 10MHz / 11.2MHz), Initial Ranging and It can also optionally support periodic ranging, multi-input multi-output (MIMO) diversity, digital I & Q interface, and MRC (Maximum Rate Combining) Diversity.

The main processor 300 may be implemented using a RAS Main Processor (RPM).

The interface unit 310 performs an Ethernet L2 switching function for communication with a control station or another base station or communication between units. That is, the interface unit 310 has an L2 switching function for internal and external communication of the base station, and provides an Ethernet interface to an external Ethernet interface and other additional devices with the control station. The interface unit 310 transmits uplink data to the control station or receives downlink data from the control station. Meanwhile, when the base station operates as a slave base station as described below, the interface unit 310 supports an interfacing function through a daisy chain with a master base station, and thus, between base stations to be described later from the master base station. Receive a synchronization message for synchronization setting. In addition, when the base station operates as a slave base station, communication with the control station is performed through an interfacing function via the master base station.

The frequency converter 320 performs low noise amplification of the band-filtered uplink signal provided from the transmission / reception unit 220 shown in FIG. 1, down-converts the frequency to convert the frequency down-conversion signal to be described later. 330, and up-converts the baseband downlink signal provided from the physical layer processor 330 to the transmission / reception unit 220.

Meanwhile, the frequency converter 320 according to the present invention may perform a digital predistortion (DPD) function in frequency downconverting the band-filtered uplink signal.

The physical layer processor 330 performs signal processing related to the physical layer of the wireless communication system, and the physical layer processor 330 according to the present invention processes a signal of 1FA / 1Sector. Specifically, the physical layer processor 330 may include a data randomization function, an interleaving function, a convolution code (CC) / convolution turbo code (CTC) function, and an FUSC. (Full Usage Sub-Channel) or PUSC (Partial Usage Sub-Channel) to selectively perform a sub-channel allocation function.

On the other hand, the physical layer processor 330 processes the baseband uplink signal transmitted from the frequency converter 320 and outputs it to the interface unit 310, and processes the downlink signal received through the interface unit 310 Output to the frequency converter 320.

Meanwhile, the clock synchronizer 340 generates a synchronized clock signal by sharing a GPS signal between each base station, and distributes the generated clock signal to each unit. The clock synchronizer 340 includes a master block when the base station including the clock synchronizer 340 is a master base station, and the slave block when the base station including the clock synchronizer 340 is a slave base station. It may include.

First, when the base station is a master base station, the master block included in the clock synchronizer 340 receives a GPS signal from a GPS antenna (not shown) included in the base station, and generates a clock signal using the received GPS signal directly. And transmits a synchronization message to the slave base station using a GPS signal for synchronization setting with at least one slave base station (not shown). The function of such a master block will be described in detail with reference to FIG. 4.

4 is a schematic block diagram of a master block. As shown, the master block 400 includes a GPS engine 410, a master controller 420, a PLL means 425, and an output / distributor 430.

First, the GPS engine 410 receives a GPS signal from a GPS antenna and extracts a 1 Pulse Per Second (PPS) signal.

Next, the master controller 420 outputs a control signal by using the time difference between the 1PPS signal provided from the GPS engine 410 and the 1PPS signal generated by itself, and provides the slave base station with an Ethernet format. A sync message is generated and output to the slave base station through the output / distributor 430 which will be described later.

Next, the PLL means 425 outputs a precise 1PPS signal using the 1PPS signal provided from the GPS engine 410 and the control signal provided from the master controller 420, and generates a clock signal using the precise 1PPS signal. do. For this purpose, the PLL means 425 may include a frequency oscillator (not shown) and a clock generator (not shown).

The output / distributor 430 branches the precise 1PPS signal and the clock signals output from the PLL means 425 by the required number to each unit, and transmits a synchronization message output from the master controller 420 to the slave base station. do.

Next, when the base station is a slave base station, the slave block included in the clock synchronizer 340 generates a clock signal by using a synchronization message provided from the master base station and distributes it to each unit. The function of such a slave block will be described in detail with reference to FIG. 5.

5 is a schematic block diagram of a slave block. As shown, the slave block 500 includes a slave controller 510, a PLL means 520, and an output / distributor 530.

First, the slave controller 510 generates a precise 1PPS signal using a synchronization message received from the master base station, and generates and outputs a control signal using a time difference between the precise 1PPS signal and the 1PPS signal generated by itself.

Next, the PLL means 520 generates a precise 1PPS signal using the control signal provided from the slave controller 510 and generates a clock signal using the precise 1PPS signal. For this purpose, the PLL means 425 may include a frequency oscillator (not shown) and a clock generator (not shown).

Next, the output / distributor 530 branches the precise 1PPS signal and the clock signal provided from the PLL means 520 by the required number and provides them to each unit.

As described above, when the base station 200 is a master base station, a 1PPS signal and a clock signal are directly generated by using the GPS signal obtained from the GPS antenna, and when the base station 200 is a slave base station, the base station 200 is transmitted from the master base station. Since the 1PPS signal and the clock signal can be generated using the synchronization message, all base stations do not need to include a device for receiving a GPS signal (for example, a GPS antenna and a GPS engine), so that the base station size as well as the unit cost of the base station Will be able to lower.

Hereinafter, a method of establishing synchronization between the above-described base stations will be described in detail with reference to FIG. 6.

6 is a diagram illustrating a base station system for explaining a synchronization setting method between a master base station and a slave base station among base stations. As can be seen in FIG. 6, the master base station 600 includes a master block 602 with a GPS engine (not shown) and a GPS antenna 604, wherein at least one slave base station 610, 620 Slave blocks 612 and 622 without a GPS engine.

In one embodiment, these master blocks 602 and slave blocks 612 and 622 may operate according to a protocol defined in the Institute of Electrical and Electronics Engineers (IEEE) 1588 standard.

First, the master block 602 included in the master base station 600 receives a GPS signal from the GPS antenna 604, generates a 1PPS signal and a clock signal from the received GPS signal, and generates the generated 1PPS signal and the clock signal. It distributes to each unit included in the master base station 600 through the interface unit 608 under the control of the main processing unit 606.

In addition, the master block 602 generates a synchronous message in the Ethernet form of the master base station 600 by using the GPS signal, and provides it to each slave base station 610 and 620 through the interface unit 608.

Meanwhile, the main units 616 of the slave base stations 610 and 620 transmit the synchronization messages transmitted from the master base station 600 by the interface units 614 and 624 of the slave base stations 610 and 620 through MII (Medium Independent Interface). , 626, the main processing unit 616, 626 analyzes the synchronization message and provides it to the slave blocks 612, 622.

Thereafter, each of the slave blocks 612 and 622 generates a 1PPS signal and a clock signal at the slave base stations 610 and 620 using the synchronization message of the master base station 600, and generates the generated 1PPS signal and the clock signal as the main processor. To each unit included in the slave base stations 610 and 620 under the control of 616 and 626.

As such, in the case of the present invention, only the master base station 600 receives the GPS signal directly from the GPS antenna 604 to generate the 1PPS signal and the clock signal, and the slave base stations 610 and 620 are the master base station 600 and the GPS signal. Since it can be shared to generate a 1PPS signal and a clock signal using a synchronization message provided from the master base station 600.

Hereinafter, referring to FIG. 7, a process of synchronizing the master base station 600 and the slave base station 610 using the synchronization message transmitted and received between the master base station 600 and the slave base station 610 shown in FIG. 6 will be described in detail. Explain. The synchronization process between the master base station 600 and the slave base station 610 greatly adjusts the current time of the slave base station 610 by measuring the offset difference between the current time of the master base station 600 and the slave base station 610. And measuring a network delay between the master base station 600 and the slave base station 610.

First, in order to adjust the current time of the slave base station 610, the master base station 600, when the synchronization message 700 is transmitted, the slave base station 610 calculates the time when the synchronization message arrived. Thereafter, when the master base station 600 transmits a follow up message 710 including the exact time of the master base station, the slave base station 610 determines the difference between the time included in the subsequent message and the time when the synchronization message arrived. To modify your current time.

Next, to measure the network delay, the slave base station 610 transmits a request message 720 to measure the time delay between the slave base station 610 and the master base station 600 to the master base station 600, Note the transmission time of the request message. Then, when the response message 730 for measuring the time delay is transmitted from the master base station 600, the slave base station 610 transmits the transmission time of the request message for measuring the time delay and the response message for measuring the time delay. Calculate the network delay using the reception time.

Through this process, the master base station 600 and the slave base station 610 share the same time, the slave base station 610 is the network delay and offset difference of the current time obtained through the periodic message exchange as described above It is used to generate a precise clock signal.

As such, by configuring the slave base station 610 and the master base station 600 by using a daisy chain in its own network, it is possible to provide a more stable and predictable fixed time delay, thereby providing a stable clock signal at the slave base station 610. You can guarantee creation.

In one embodiment, each of the main processor 606 included in the master base station 600 and the main processor 616, 626 included in the slave base stations 610, 620 may each have a public IP address. The master block 602 included in the master base station 600 and the slave blocks 612 and 622 included in the slave base stations 610 and 620 may have a private IP address.

In addition, the master base station 600 and the slave base stations 610 and 620 may be connected to each other in a daisy-chain type.

On the other hand, in the base station system shown in Figure 6, the interface unit 606, 614, 624 included in each base station (600, 610, 620) in order to prevent the synchronization message generated by the master base station to enter the commercial network ) Have a tagged VLAN function for each port. This is because, when the synchronous message in the form of Ethernet packet transmitted and received between the master base station 600 and the slave base stations 610 and 620 flows into the commercial network, it may cause serious confusion on the commercial network due to the duplication of private IP addresses. .

Referring back to FIG. 2, the transmission / reception unit 220 adjusts the signal level of the frequency up-converted signal transmitted from the main unit 210 to provide the downlink signal to the RF front end unit 230 to be described later, and RF Low-noise amplification of the band-filtered uplink signal transmitted from the front end unit 230, and frequency down-converts to transmit the frequency down-converted signal to the main unit 210 described above.

The transmission / reception unit 220 operates a reception path and a transmission path by TDD (Time Division Duplex) synchronization, and includes a digital attenuator therein to perform a gain control function. In particular, in the reception path, gain may be compensated according to the level at which the RF signal is input by using an automatic gain control (AGC) / receive signal strength indicator (RSSI) function.

 The RF front end unit 230 transmits the uplink signal transmitted from the terminal to the transmit / receive unit 220 by filtering using a band pass filter (BPF) and the downlink transmitted from the transmit / receive unit 220. Band-filters the signal using a band pass filter to transmit the signal to the terminal.

Meanwhile, the above-described base station 200 may further include an amplifying unit 240 for amplifying the downlink signal provided from the transmitting and receiving unit 220. The amplifying unit 240 linearly amplifies the downlink signal to be transmitted to the terminal without distortion. That is, the downlink signal provided from the transmission / reception unit 220 is amplified to be a standardized downlink signal level. At this time, the amplifying unit 240 amplifies the downlink signal only during the time that there is a downlink signal to be transmitted to the terminal in synchronization with the TDD frame.

In one embodiment, when the main unit 210 supports the MIMO function, the above-described RF front end unit 230 and amplification unit 240 may be implemented in plurality, as shown in FIG. 2 illustrates a case in which the main unit 210 supports 2 를 2 MIMO, and since the main unit 210 supports 2ⅹ2 MIMO, the RF front end unit 230 and the amplification unit 240 are implemented in two. Able to know.

The functions of the units included in the base station described above may be implemented in the form of program instructions that can be executed by various computer means, and recorded in a computer-readable recording medium. In this case, the computer-readable recording medium may include program instructions, data files, data structures, and the like, alone or in combination. On the other hand, the program instructions recorded on the recording medium may be those specially designed and configured for the present invention or may be available to those skilled in the art of computer software.

The computer-readable recording medium includes a magnetic recording medium such as a magnetic medium such as a hard disk, a floppy disk and a magnetic tape, an optical medium such as a CD-ROM and a DVD, a magnetic disk such as a floppy disk, A magneto-optical media, and a hardware device specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. The recording medium may be a transmission medium such as an optical or metal wire, a waveguide, or the like including a carrier wave for transmitting a signal specifying a program command, a data structure, or the like.

In addition, program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

On the other hand, those skilled in the art will understand that the present invention described above can be implemented in other specific forms without changing the technical spirit or essential features.

For example, in the above-described embodiment, the master base station and the slave base station each include a master block and a slave block, so that the slave base station separately generates 1PPS signals and clock signals using the synchronization message included in the synchronization message generated by the master base station. It was described as producing. However, in a modified embodiment, the clock signal itself generated by the master base station may be transmitted to the slave base station. In this case, the slave base station may use the clock signal transmitted from the master base station as its clock signal without generating a clock signal separately.

Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

1 is a diagram showing a network configuration of a general wireless communication system.

Figure 2 is a block diagram schematically showing the configuration of a base station according to an embodiment of the present invention.

3 is a block diagram showing a schematic configuration of the main unit shown in FIG.

4 is a block diagram showing a schematic configuration of a master block of the clock synchronizer shown in FIG.

FIG. 5 is a block diagram illustrating a schematic configuration of a slave block of the clock synchronizer illustrated in FIG. 3.

6 is a block diagram schematically illustrating a configuration of a base station system according to an embodiment of the present invention.

7 is a diagram illustrating a process of synchronizing synchronization between a master base station and a slave base station using a synchronization message according to the present invention.

Claims (17)

An RF front end unit for band-passing and transmitting an uplink signal or band-filtering and transmitting a downlink signal; A transmission / reception unit configured to low-noise amplify the band-filtered uplink signal and frequency down-convert to output a frequency down-converted signal, or adjust a signal level with respect to a frequency up-converted signal to output the downlink signal; And The baseband uplink signal for the frequency down-converted signal is inversely modulated and changed into an uplink IP packet and transmitted to an access control router (ACR), or a downlink IP packet received from the ACR is received and the downlink IP packet is changed. A main unit for modulating a baseband downlink signal for the frequency up-converted signal, The main unit, An interface unit supporting an interfacing function with the ACR and an interfacing function that can be extended in a daisy chain manner; And And a clock synchronizer for generating a clock signal using a GPS signal or a synchronization message and providing the generated clock signal. The method of claim 1, wherein the main unit, A physical layer processor configured to process a physical layer (PHY Layer) protocol signal of IEEE 802.16 d / e with respect to the baseband uplink signal or the baseband downlink signal; And And a main processor for performing a call process function of IEEE 802.16 d / e, a change of an IP packet, and a control and management function of the base station. The method of claim 1, wherein the main unit, And a frequency converter configured to process and output the frequency down-converted signal as the baseband uplink signal, or output the frequency up-converted signal by frequency up-converting the baseband downlink signal. The method of claim 1, wherein the clock synchronization unit, A master block for receiving the GPS signal from a GPS antenna, generating the clock signal using the GPS signal directly, and generating a synchronization message using the GPS signal to establish synchronization with another base station; or And one of the slave blocks generating the clock signal using the synchronization message. Claim 5 was abandoned upon payment of a set-up fee. The method of claim 4, wherein the master block, A GPS engine for receiving the GPS signal from the GPS antenna and extracting a first 1 pulse per second (PPS) signal from the received GPS signal; A master control unit generating a control signal by using a time difference between the first 1PPS signal and a second 1PPS signal generated directly, and generating the synchronization message; PLL means for generating a third 1PPS signal and the clock signal using the first 1PPS signal and the control signal; And And an output / distribution unit for distributing the third 1PPS signal and the first clock signal generated by the PLL means to the respective units, and transmitting the synchronization message to the other base station through the interface unit. Base station. Claim 6 was abandoned when the registration fee was paid. The method of claim 4, wherein the slave block, A slave controller configured to generate a control signal using a time difference between a fourth 1PPS signal generated by using the synchronization message transmitted from another base station and a fifth 1PPS signal generated directly; PLL means for generating a sixth 1PPS signal and the clock signal using the control signal generated by the slave controller; And And an output / distributor for distributing the sixth 1PPS signal and the clock signal generated by the PLL means to the units. Claim 7 was abandoned upon payment of a set-up fee. The method of claim 4, wherein The master block is characterized in that for generating the synchronization message in the form of Ethernet (Ethernet) packet. Claim 8 was abandoned when the registration fee was paid. The method of claim 2, And the main processor has a public IP address and the clock synchronizer has a private IP address. Claim 9 was abandoned upon payment of a set-up fee. The method of claim 1, The interface unit is characterized in that the Tagged VLAN function is provided for each port. Claim 10 was abandoned upon payment of a setup registration fee. The method of claim 1, If the main unit supports the Multi Input Multi Output (MIMO) function of the base station, the base station, characterized in that a plurality of the RF front end unit is implemented. Claim 11 was abandoned upon payment of a setup registration fee. The method of claim 1, And an amplifying unit for receiving and linearly amplifying the downlink signal from the transmitting and receiving unit. Claim 12 was abandoned upon payment of a registration fee. The method of claim 11, delete delete delete Claim 16 was abandoned upon payment of a setup registration fee. A master base station for generating a synchronization message for synchronizing with a slave base station using a first 1PPS signal, a first clock signal using a GPS signal received from a GPS antenna, and transmitting the synchronization message to a slave base station; And At least one slave base station generating a second 1PPS signal and a second clock signal by using a synchronization message transmitted from the master base station, The master base station, An RF front end unit for band-passing and transmitting an uplink signal or band-filtering and transmitting a downlink signal; A transmission / reception unit configured to low-noise amplify the band-filtered uplink signal and frequency down-convert to output a frequency down-converted signal, or adjust a signal level with respect to a frequency up-converted signal to output the downlink signal; And The baseband uplink signal for the frequency down-converted signal is inversely modulated and changed into an uplink IP packet and transmitted to an access control router (ACR), or a downlink IP packet received from the ACR is received and the downlink IP packet is changed. A main unit for modulating a baseband downlink signal for the frequency up-converted signal, The main unit, An interface unit supporting an interfacing function with the ACR and an interfacing function that can be extended in a daisy chain manner; And Receiving the GPS signal from the GPS antenna, generating a synchronization message for synchronizing the first 1PPS signal, the first clock signal, and the at least one slave base station using the received GPS signal, And a clock synchronizer for distributing the generated first 1PPS signal and the first clock signal to respective units included in the master base station, and transmitting the synchronization message to the at least one slave base station. Claim 17 has been abandoned due to the setting registration fee. A master base station for generating a synchronization message for synchronizing with a slave base station using a first 1PPS signal, a first clock signal using a GPS signal received from a GPS antenna, and transmitting the synchronization message to a slave base station; And At least one slave base station generating a second 1PPS signal and a second clock signal using a synchronization message transmitted from the master base station, The at least one slave base station, An RF front end unit for band-passing and transmitting an uplink signal or band-filtering and transmitting a downlink signal; A transmission / reception unit configured to low-noise amplify the band-filtered uplink signal and frequency down-convert to output a frequency down-converted signal, or adjust a signal level with respect to a frequency up-converted signal to output the downlink signal; And The baseband uplink signal for the frequency down-converted signal is inversely modulated and changed into an uplink IP packet and transmitted to an access control router (ACR), or a downlink IP packet received from the ACR is received and the downlink IP packet is changed. A main unit for modulating a baseband downlink signal for the frequency up-converted signal, The main unit, An interface unit for receiving the synchronization message from the master base station through a daisy chain interfacing function with the master base station; And Generating the second 1PPS signal and the second clock signal by using the synchronization message received from the master base station, and distributing the second 1PPS signal and the second clock signal to each unit included in the slave base station; A base station system comprising a clock synchronization unit.

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