KR100696335B1 - Radio Frequency Transmitter of Code Division Multiplexing Mobile Base Station System - Google Patents

Abstract

The RF transmitter of a CDMA mobile communication base station system digitally modulates the baseband signal converted into a spread spectrum signal for each FA by using the same path for the 3FA frequency in the multicarrier mobile communication base station system supporting 3FA. Digitally combines the modulated signals for each FA and then sequentially upconverts them to intermediate and RF frequencies to extend the digital domain before the transmission frequency so that the RF processing system can be more stably maintained over temperature and time. In addition, by using the same path for the 3FA frequency in the RF part in the system supporting 3FA, not only the configuration of the RF device but also the overall structure of the base station system can be simplified to reduce the economic cost loss to the minimum. Easy to expand FA because it can be expanded by 3FA at the time of expansion The.

Description

Apparatus for transmitting radio frequency in a base station of a mobile communication system

1 is a block diagram illustrating a general mobile communication base station system;

2 is a block diagram of a radio frequency transmission apparatus of a code division multiple access mobile communication base station system according to the prior art;

3 is a block diagram of a radio frequency transmission apparatus of a code division multiplex mobile communication base station system according to a first embodiment of the present invention;

4 is a block diagram illustrating a detailed block structure of the digital modulator shown in FIG. 3;

Fig. 5 is a signal waveform diagram of a frequency domain when a signal in the frequency domain when the digitally modulated 3FA signal is digitally coupled;

6 is a block diagram of a radio frequency transmitter of the code division multiplex mobile communication base station system according to the second embodiment of the present invention;

FIG. 7 is a block diagram illustrating a detailed block structure of the digital modulator shown in FIG. 6; FIG.

<Explanation of symbols for main parts of drawing>

11, 12, 13: channel card 90: transmitter

100: digital signal processor 101, 102, 103: digital modulator

104: D / A converter 110: analog upstream

111, 113: first and second upper portions 112: band pass filter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio frequency (RF) transmitting apparatus of a code division multiple system (hereinafter referred to as CDMA) mobile communication base station system, and more particularly, supports 3FA (Frequency Assignment). In the multi-carrier mobile communication system, the RF part is digitally modulated from the baseband signal converted into a spread spectrum signal using the same path with respect to the 3FA frequency, digitally combined with the modulated signal, and then sequentially raised to the intermediate frequency and the RF frequency. An RF transmitter of a CDMA mobile communication base station system for converting and transmitting.

A general CDMA mobile communication base station system is composed of a switching system and cell equipment. This includes many of the unit functional units that make up the system, and these units are implemented in various types of equipment.

The core of such a mobile base station system is a digital shelf that includes a channel card, a sector interface card, an analog common card, and an end card. The transceiver self converts an intermediate frequency signal (hereinafter referred to as IF) output from the digital self into UHF and down-converts the received UHF into IF.

In addition, the transceiver itself includes a sector access card for combining the baseband forward signal received from the channel card and converting it up to the IF signal. Such a sector access card receives a combined baseband transmission signal from an analog common card, combines and amplifies them. The combined signal is passed through the low pass filter (LPF) and combined with the IF signal, i.e., 0 ° and 90 ° delayed signals at 4.95 MHz, into the RF rack as an IF signal of 4.95 MHz through the band pass filter (BPF). Send. Therefore, the RF rack is to convert the 4.95Mhz IF signal received for signal transmission through the antenna to UHF signal.

Hereinafter, a general digital mobile communication base station system will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram of a general digital mobile communication base station system. Referring to FIG. 2, the configuration thereof is referred to as a BTS control processor (hereinafter referred to as a BCP). (2) and a packet router function between a base station and a base station controller (hereinafter referred to as BSC) (1) through an E1 line or a T1 line, and a high-definition (HDLC) between each processor in the base station. BTS Interconnection Network (BIN) 3 for interfacing packet data, and generating reference frequency and timing synchronization signals to synchronize each processor in the base station and timing the neighboring base station. Time and Frequency Unit (TFU) 4 which performs synchronization, and modulates and demodulates data signals and voice signals transmitted and received through the CDMA channel. A digital signal processing unit (hereinafter referred to as DU) 5, converts a UHF signal received from a mobile station into an IF signal, transfers the converted IF signal to the DU 5, and inputs it from the DU 5 It is composed of an RF signal processing unit (hereinafter referred to as RFU) 6 which receives the IF signal and converts it into a UHF signal, and amplifies the converted UHF signal to a predetermined level. Here, the RF signal processing apparatus 6 is divided into an RF receiver and an RF transmitter.

Hereinafter, an RF transmitter according to the prior art will be described in detail with reference to FIG. 2. 2 is a block diagram of an RF transmitter of a CDMA mobile communication base station system according to the prior art.

First, in the conventional RF transmitter, three channel cards 11, 12, and 13 respectively outputting digital baseband signals for supporting 3FA to I / Q (Inphase / Quarderature) channels for each FA. And convert each baseband signal of each FA's I / Q channel outputted through each channel card 11, 12, 13 into an analog signal after being connected to each channel card 11, 12, 13, respectively. Three analog processing units 20, 30, and 40 for outputting a modulated analog baseband signal by QUK (Kuarderature Phase Shifting Keying) modulation, and each analog processing unit (20, 30, 40). Three analog upstream parts (50, 60, 70) for converting each FA-signal output from the 30, 40 to an intermediate frequency, and converting the converted intermediate frequency back to a transmission frequency (RF signal) and outputting the same; By combining the transmission frequency of each FA output from the three analog upstream parts (50, 60, 70) After a predetermined level amplification of the transmission coupling unit 80 and the transmission frequency signal output from the transmission coupling unit 80 through my path, and by limiting the band so as not to affect the frequency used in other communication methods through the antenna It consists of a transmitter 90 for transmitting an RF signal. Here, the baseband signals output from the three channel cards, that is, the channel cards for each FA, are 0FA-I, 0FA-Q, 1FA-I, 1FA-Q, 2FA-I, and 2FA-Q.

Each FA (OFA, 1FA, 2FA) analog processing unit (20, 30, 40) is a D / A conversion unit 21 for converting the baseband signal output from the channel card (11, 12, 13), respectively, into an analog signal (21) , 31, 41, and analog modulators 22, 32, and 42 for up-converting the analog baseband signals output from the DA converters 21, 31, and 41 to a signal of 4.95 MHz by QPSK modulation. .

In addition, the analog upstream unit (50, 60. 70) for each FA is composed of a local oscillator (not shown) and a mixer, and the 4.95MHz signal output from the analog modulation unit (22, 32, 42) for each FA 1.25Mhz of the first uplinks 51, 61, 71 for upconverting to intermediate frequencies using a local oscillator and a mixer, and the intermediate frequency signals converted at the first upstreams 51, 61, 71 for each FA. A channel filter 52, 62, and 72 for filtering and outputting each of the signals with a bandwidth of?, And a second oscillator for converting the signal filtered by the channel filters 52, 62, and 72 to a transmission frequency with a local oscillator (not shown). It consists of the upper part 53, 63, 73. Here, the local oscillator in the second upstream portion 53, 63, 73 uses a variable local oscillator to distinguish the channels.

The operation of the RF transmitter of the CDMA mobile communication base station system according to the prior art having such a configuration will be described.

First, the CDMA digital signals from each FA channel card (11, 12, 13) and each FA and I / Q channel (0FA-I, 0FA-Q, 1FA-I, 1FA-Q, 2FA-I, 2FA-) Q) is output to the D / A converters 21, 31, and 41 of the analog processing units 20, 30, and 40, respectively. At this time, the output signal is a baseband signal.

The baseband signals of the I / Q channels output from the respective channel cards 11, 12, and 13 are converted into analog signals through the respective D / A converters 21, 31, and 41, and then the analog modulators 22 , 32, 42).

The analog modulators 22, 32, and 42 perform QPSK modulation on the I / Q channels of the analog baseband signals output from the D / A converters 21, 31, and 41 for each FA, and then for each FA. The I-channel and Q-channel signals are combined and transmitted to the first upstream portions 51, 61, and 71 of the analog upstream portions 50, 60, and 70. At this time, the baseband signal is up-converted into a signal of 4.95 MHz.

The first upstream portions 51, 61, and 71 of the analog upstream portions 50, 60, and 70 are configured to combine the I-channel and Q-channel signals output from the analog modulation units 22, 32, and 42 with the local oscillator. It is converted to an intermediate frequency using a mixer and transmitted to the channel filters 52, 62, and 72. In other words, the I-channel and Q-channel combined signal and the local frequency generated from the local oscillator are mixed by the mixer and converted into the intermediate frequency.

The signal converted to the intermediate frequency removes the out-of-band signal through channel filters 52, 62, and 72 for protecting its own transmission signal for each FA, and then outputs the signal to the second upstream parts 53, 63, and 73. . In this case, the channel filters 52, 62, and 72 are SAW filters having a bandwidth of 1.25 MHz.

The second upstream part 53, 63, 73 converts the intermediate frequency signal outputted from the channel filters 52, 62, 72 into a transmission frequency using a local oscillator, and then converts the transmission frequency of each FA into a transmission coupling. The local oscillator used in the second upstream part 53, 63, 73 uses a variable local oscillator to distinguish channels. Therefore, the signals of each local oscillator are generated at a distance equal to each FA frequency interval.

The three FA signals converted to the transmission frequency are combined in the transmission combiner 80, and the combined three FA signals are output to the transmitter 90 and amplified through a low power amplifier (not shown), and then applied to other communication schemes. It transmits through the antenna after limiting the band so as not to affect the frequency used.

However, the RF transmitter of the CDMA mobile communication base station system according to the prior art implements hardware which upconverts the baseband signal from the baseband signal to the transmission frequency separately for each FA, thereby implementing a large cost due to hardware implementation. There is a problem in that the required size and the structure thereof are complicated, thereby increasing the size of the system.

 In addition, there is a problem that the stability of the system with respect to temperature and time by processing the process of up-converting the baseband signal to the intermediate frequency in an analog manner.

In addition, since the frequency up process is performed for each FA separately and the FA can be extended by 1 FA, a great difficulty in FA expansion, a complexity of hardware structure, and a large cost increase are caused.

Accordingly, the present invention has been made to solve the above-mentioned problems according to the prior art, an object of the present invention is to use a band in the multi-carrier mobile communication base station system supporting 3FA using the same path for the 3FA frequency RF transmitter of a CDMA mobile communication base station system for digitally modulating baseband signals converted into spread signals for each FA, digitally combining the modulated signals for each FA, and then sequentially converting them up to intermediate and RF frequencies In providing.

A feature of an RF transmitter of a CDMA mobile communication base station system according to the present invention for achieving the above object is a plurality of channel cards for providing I / Q channel baseband signals for multi-FA, and a transmission antenna An RF transmitting apparatus of a mobile communication base station system comprising: a) digitally modulating baseband signals for each FA I / Q channel provided by the plurality of channel cards for each FA, and b) each digitally modulated FA digitally. Digital signal processing means for converting the combined multi-FA digital modulation signal into an analog signal after combining the modulation signal; An analog frequency up-converting means for performing a first up-conversion of the multi-FA signal converted into an analog signal by the digital signal processing means to an intermediate frequency, and then performing a second up-conversion of the first up-converted intermediate frequency signal to a transmission frequency; ; And a transmitting means for amplifying the second frequency up-converted transmission frequency signal by the analog frequency up-converting means to an arbitrary transmission output level and then transmitting the same through the transmission antenna.

In addition, another aspect of the present invention is a RF transmission apparatus of a mobile communication base station system having a plurality of channel cards and I / Q channel baseband signals for multiple FAs and a transmitting antenna, respectively, each FA channel. After each CDMA baseband signal output from the card is QPSK-modulated for each FA, the modulated QPSK-modulated signal for each FA is serially combined with the QPSK-modulated signal of the lower or upper FA from the highest or lowest FA, and then sequentially A digital modulator for each FA for outputting a digital modulated signal; A D / A converter converting the combined multi-FA QPSK modulated signal output from the highest or lowest FA digital modulator into an analog signal and outputting the analog signal to the analog frequency up-conversion unit; A first uplink unit for up-converting the multi-FA combined analog modulated signal output from the D / A converter to an arbitrary intermediate frequency; A band pass filter for band-filtering the combined multi-FA intermediate frequency signal up-converted in the first upstream part to an arbitrary bandwidth; A second uplink unit converting the multi-FA intermediate frequency signal filtered by the band pass filter into a transmission RF frequency and outputting the converted RF frequency to the transmitter; And a transmitting means for amplifying the second frequency up-converted transmission frequency signal by the analog frequency up-converting means to an arbitrary transmission output level and then transmitting the same through the transmission antenna.

In another aspect of the present invention, the band pass filter uses a 3.75MHz SAW filter for passing a multi-FA band.

Hereinafter, an RF transmitter of a CDMA mobile communication base station system according to the present invention will be described in detail with reference to the accompanying drawings. At this time, the description of the same components that overlap with the prior art shown in Figure 2 will be omitted.

(First embodiment)

3 is a block diagram of an RF transmitter of a CDMA mobile communication base station system according to a first embodiment of the present invention, and FIG. 4 is a block diagram showing a detailed block diagram of the digital modulation unit shown in FIG. FIG. 5 is a signal waveform diagram of a frequency domain when digitally modulated 3FA signals are digitally coupled. Referring to FIG. 5, the basis of I / Q channels output from respective FA channel cards 11, 12, and 13 is shown. A digital signal processor 100 for digitally modulating the band signals, combining all the baseband signals for each modulated I / Q channel, and then converting the combined baseband signals into analog signals and outputting the analog signals; After converting the analog signal output from the 100 to the intermediate frequency signal first up-converted, converts the up-converted intermediate frequency into a transmission frequency signal and outputs the analog upstream unit 110 and the analog upstream unit A transmission unit 90 for amplifying a predetermined frequency of the output frequency signal output from the 110, and then transmits through the antenna.

The digital signal processing unit 100 includes digital modulation units 101, 102, and 103 for QPSK modulation of the CDMA baseband signals output from the channel cards 11, 12, and 13 for each FA for each FA, and the digital modulation unit 101. Combining unit 105 for combining the three FA signals modulated in each of the, 102, 103, and 3FA QPSK modulated signal combined in the combiner 105 to convert the analog signal to the analog upstream unit 110 It consists of the D / A conversion unit 104. Here, the digital modulators 101, 102, and 103, as shown in Fig. 4, perform a low pass filter for filtering the baseband signals of the I and Q channels output from the channel cards 11, 12, and 13 of each FA. (a, a '), an interpolation filter (c, c') for interpolating baseband signals of low-pass filtered I / Q channels, and a digital output for outputting an arbitrary local frequency with a phase difference of 90 degrees. Local oscillator (b), each local frequency having a phase of 0 ° and 90 ° generated in the digital local oscillator (b), and each digital low pass filter (a, a ') and interpolation filter (c, c'). Mixers (d, d ') for mixing the baseband signals of the I and Q channels sequentially passed through the QPSK modulated baseband signals, and an adder (e) for adding the QPSK modulated I and Q channel signals. It consists of. Here, the local frequencies generated by the digital local oscillator b in each of the digital modulators 101, 102, and 103 are different from each other, i.

The analog upstream unit 110 includes a first upstream unit 111 for converting an analog-converted 3FA combined signal output from the D / A conversion unit 104 of the digital signal processing unit 100 into an intermediate frequency signal, and a first A band filter 112 for filtering the 3FA intermediate frequency signal converted by the uplink unit 111 to pass only the 3.75 MHz band, and an upconverting intermediate frequency signal filtered by the band filter 112 into a transmission frequency signal to transmit the signal to the transmission unit 90 It is composed of a second upstream portion 113 for outputting. Here, the first upstream part 111 includes a local oscillator for generating a fixed local frequency for converting the analog signal output from the D / A converter 104 of the digital signal processor 100 into an intermediate frequency. . The band filter 112 is a SAW filter having a 3.75 MHz bandwidth for accurately passing an intermediate frequency signal combined with a 3FA signal, and the reason for using the 3.75 MHz bandwidth is 1.25 MHz because the separation distance between each FA is 1.25 MHz. This is to pass the 3FA signal combined with the FA signal.

The operation of the RF transmitter of the CDMA mobile communication base station system according to the first embodiment of the present invention having the above configuration will be described.

First, the channel cards 11, 12, and 13 transmit CDMA baseband signals to the digital modulators 101, 102, and 103 of the digital signal processor 100 for each FA and each of the I and Q channels.

The transmitted baseband signals of the CDMA I and Q channels pass sequentially through the respective digital low pass filters (a, a ') and the interpolation filters (c, c') for smooth digital modulation. The signal passed in this way is QPSK modulation, which is a transmitter modulation method, for each FA (0FA, 1FA, 2FA), and then sums the modulated I and Q channel signals for each FA. That is, the baseband signals for the I channel and the Q channel input to the digital modulators 101, 102, and 103 for each FA are digital low pass filters (a, a ') in the digital modulators (101, 102, 103). ) And the interpolation filter (c, c '), respectively, and then the I and Q channel baseband signals are mixed with the local frequency and the 0 ° and 90 ° phases generated by the digital local oscillator (b). After mixing and modulating at (d, d '), the modulated respective I and Q channel signals are summed together through an adder e. At this time, the digital local oscillator (b) generated to perform modulation performs a channel selection function. The local frequency generated by the digital local oscillator (b) is spaced apart by a frequency interval of 1.25 MHz for each FA. Occurs. For example, when the digital local oscillator (b) of the digital modulator 101 used for 0FA uses 10 MHz, the digital local oscillator (b) of the digital modulator 102 used for 1FA uses 11.25 MHz and 2FA. The digital local oscillator (b) of the digital modulator 103 to be used uses 12.50 MHz.

In this manner, the signals obtained by adding the digitally modulated I, Q channels by the respective digital modulators 102, 103, and 104 for each FA are combined by the combiner 105. Here, the signal waveform of the frequency domain simulated by combining the digitally modulated 3FA signal is shown in FIG.

The combined signal for 3FA (0FA, 1FA, 2FA) is output to the D / A converter 104 and converted into an analog signal, and then the converted analog signal is the first upstream part of the analog upstream part 110. 111 is output to the first frequency upstream 111 is converted to the intermediate frequency. At this time, the local oscillator used to convert the input analog signal to the intermediate frequency generates a fixed local frequency. Therefore, the intermediate frequency converted by the first upstream part 111 has a constant center frequency value having a band of 3FA.

The intermediate frequency signal converted by the first upstream part 111 is a band filter 112 to protect the 3FA signal used from the harmonics, spurious, and local oscillator generated signals passing through the mixer. Pass). In this case, the band filter 112 uses a SAW filter having a 3.75MHz bandwidth to accurately pass the 3FA combined signal.

The signal passing through the bandpass filter 112 is output to the second upstream part 113, converted into a transmission frequency RF, and output to the transmitter 90. At this time, the local oscillator used for converting the intermediate frequency into the transmission frequency in the second upstream 113 as well as the first upstream 111 generates a fixed local frequency. Therefore, the transmission frequency is to have a constant center frequency having a band of 3FA.

The transmission frequency signal converted and output from the second upstream part 113 is amplified by the transmission power of the base station in the transmission unit 90 in the transmission unit 90, and after the band is limited so as not to affect the frequency used in other communication methods, through the antenna. It is sent out.

(Second embodiment)

FIG. 5 is a block diagram of an RF transmitter of a CDMA mobile communication base station system according to a second embodiment of the present invention. The same components as those of the prior art shown in FIG. The same components as those of the first embodiment according to the present invention will be omitted and described.

First, the RF transmitting apparatus of the CDMA mobile communication base station system according to the second embodiment of the present invention deletes the combiner 105 of the digital signal processing unit 100 shown in the first embodiment. The modulator 103 is identical to the configuration of the digital modulator as shown in FIG. 4, and the digital modulators 101 and 102 for 0FA and 1FA are arranged in the digital modulator 103 shown in FIG. The adder f is comprised, respectively.

That is, the signal modulated by the adder e of the digital modulator 103 for 2FA is outputted to the adder f of the digital modulator 102 for 1FA, and thus the adder (1) of the digital modulator 102 for 1FA. e) is firstly coupled to the modulated I / Q combined signal in 1), and the modulated signal 2FA + 1FA firstly coupled in the adder f of the digital modulator 102 for 1FA is digitally modulated for 0FA. It outputs to the adder f of (101).

Therefore, the adder f of the digital modulator 101 for 0FA is an I / Q combined signal for the OFA output from the adder e of the digital modulator 101 for 0FA and the digital modulator for 1FA. Secondary combination with the I / Q channel primary combined signal for 2FA and 1FA output from the adder (f) of (102) to combine the combined signal (0FA + 1FA + 2FA) for each FA D / A conversion unit ( 104).

The RF transmitter of the CDMA mobile communication base station system according to the first and second embodiments of the present invention as described above will be briefly summarized.

First, when the channel cards 101, 102, and 103 transmit baseband signals for FA and I / Q channels, the digital processing units 101, 102, and 103 digitally process these baseband signals for each FA. After the modulation, the modulated frequency signals for each FA are combined in series or in parallel by the combiner 105. At this time, the digital local oscillator b for each FA used to perform modulation in the digital processing units 101, 102, and 103 generates a local frequency at an interval of 1.25 MHz. Therefore, the uplink digital signal maintains the channel interval as much as FA.

The digital signal coupled in series or parallel as described above is converted into an analog signal using the D / A converter 104, and then the converted analog signal is converted into an intermediate frequency at the first upstream part 111 of the analog upstream part 110. Upconversion to.

The intermediate frequency signal thus converted is band-filtered by the SAW filter 112 of 3.75 MHz, and then applied to the second upstream 113 to be pictorially converted into a transmission frequency. In this case, the local frequency generated by the local oscillator in the second upstream part 113 generates a fixed local frequency unlike the conventional one, that is, unlike generating a different local frequency for each FA.

The transmission frequency signal up-converted by the second upstream part 113 is applied to the transmitter 90, amplified to a level for the final output of the base station transmitter, and then transmitted through an antenna.

The RF transmitter of the CDMA mobile communication base station system according to the present invention as described above is a baseband in which the RF portion is converted into a spread spectrum signal using the same path for the 3FA frequency in a multicarrier mobile communication base station system supporting 3FA. By digitally modulating the signal for each FA, digitally combining the modulated signal for each FA, and sequentially upconverting the signal to an intermediate frequency and an RF frequency and transmitting the same.

By extending the digital domain before the transmission frequency, there is an effect that the RF processing system can be more stably maintained with respect to temperature and time.

In addition, by using the same path for the 3FA frequency in the RF part in the system supporting 3FA, not only the configuration of the RF device but also the structure of the base station system can be simplified to reduce the economic cost loss to a minimum. have.

In addition, since FA can be extended by 3FA, the FA can be easily expanded.

Claims (13)

In the RF transmitting apparatus of a mobile communication base station system having a plurality of channel cards for providing I / Q channel baseband signals for multiple FAs and a transmitting antenna, a) digitally modulating baseband signals for each FA I / Q channel provided by the plurality of channel cards for each FA, b) digital signal processing means for combining each digitally modulated FA digital modulated signal and then converting the combined multiFA digital modulated signal into an analog signal; An analog frequency up-converting means for performing a first up-conversion of the multi-FA signal converted into an analog signal by the digital signal processing means to an intermediate frequency, and then performing a second up-conversion of the first up-converted intermediate frequency signal to a transmission frequency; ; And a transmitting means for amplifying the second up-converted transmission frequency signal by the analog frequency up-converting means to an arbitrary transmission output level and transmitting the same through the transmission antenna. RF transmitter. The method of claim 1, The digital signal processing means includes: a digital modulation unit for each FA for QPSK modulation of each CDMA baseband signal output from the channel card for each FA for each FA; A combiner for coupling the digitally modulated signals modulated by the respective digital modulators for each FA in parallel; And a D / A converter converting the multi FA QPSK modulated signal coupled by the combiner into an analog signal and outputting the analog frequency up-converting means. The method of claim 2, A plurality of digital low pass filters for low-pass filtering each baseband signal of an I / Q channel output from a corresponding FA channel card to an arbitrary bandwidth for QPSK modulation; A plurality of interpolation filters for interpolating respective baseband signals for the I and Q channels filtered by the plurality of digital lowpass filters and filtering each other with a different frequency signal; Local oscillators each generating an arbitrary local frequency having a phase difference of 90 degrees; A plurality of mixers each mixing a local frequency having a phase difference of 90 ° generated by the local oscillator and signals of I and Q channels respectively having passed through the plurality of interpolation filters; And an adder for adding the mixed I-channel signals and Q-channel signals, respectively, in the plurality of mixers. 4. The RF transmitter of a CDMA mobile communication base station system according to claim 3, wherein the local frequency generated by the local oscillator in each digital modulation unit for each FA is generated at a distance of 1.25 MHz, which is a distance between FAs. . The method of claim 2, In the digital signal processing unit, the combination of the modulation signals for each FA is used to output the modulated signal modulated by the N-th digital modulator among the digital modulators for each FA to the N-1 th digital modulator to modulate the N-1 th digital modulator. Firstly combines the modulated signal corresponding to the N-1 FA, and outputs the first-modulated N + (N-1) FA modulated signal to the digital modulator corresponding to the N-2 FA. An RF transmitter of a CDMA mobile communication base station system, characterized in that it uses a series combining method for outputting the multiple FA modulated signal, which is secondarily combined with the modulated N-2 FA modulated signal, to the D / A converter. The method of claim 1, The analog frequency up-converting means comprises: a first up-up part for up-converting the multi-FA analog modulated signal output from the digital signal processing means to an arbitrary intermediate frequency; A band pass filter for band-filtering the combined multi-FA intermediate frequency signal up-converted in the first upstream to an arbitrary bandwidth; And a second uplink unit for converting the multi-FA intermediate frequency signal filtered by the band pass filter into a transmission RF frequency and outputting the same to the transmission means. The method of claim 6, The first upstream part comprises a local oscillator providing a fixed local frequency for upconverting an input analog signal to an intermediate frequency; And a mixer converting the fixed constant local frequency signal provided from the local oscillator and the input analog signal into an arbitrary intermediate frequency so as to have a constant center frequency having a band of multi FA. RF transmitter of mobile communication base station system. The method of claim 6, The band pass filter is a RF transmitter of a CDMA mobile communication base station system, characterized in that the 3.75MHz SAW filter for passing the multi-FA band. The method of claim 6, The second upstream part and the local oscillator for providing a fixed local frequency for up-converting the intermediate frequency signal passed through the band pass filter to a transmission frequency; And a mixer configured to mix the fixed constant local frequency signal provided by the local oscillator and the intermediate frequency signal and up-convert to an arbitrary transmission RF frequency to have a constant center frequency having a band of multi FA. RF transmitter for mobile communication base station system. In the RF transmitting apparatus of a mobile communication base station system having a plurality of channel cards for providing I / Q channel baseband signals for multiple FAs and a transmitting antenna, A digital modulation unit for each FA for QPSK modulation of each CDMA baseband signal output from each FA card for each FA; A combiner for combining the respective digital modulated signals for each FA modulated by the respective digital modulators for each FA; And a D / A converter converting the multi FA QPSK modulated signal coupled by the combiner into an analog signal and outputting the analog frequency upconverting means. The analog frequency up-converting means A first uplink unit for up-converting the multi-FA combined analog modulated signal output from the D / A converter to an arbitrary intermediate frequency; A band pass filter for band-filtering the combined multi-FA intermediate frequency signal up-converted in the first upstream to an arbitrary bandwidth; And a second upstream unit converting the multi-FA intermediate frequency signal filtered by the band pass filter into a transmission RF frequency and outputting the converted RF to a transmission unit. The transmitting unit amplifies the second frequency up-converted transmission frequency signal by the analog frequency up-conversion unit to an arbitrary transmission output level, and then transmits it through the transmission antenna. . The method of claim 10, The band pass filter is a RF transmitter of the CDMA mobile communication base station system, characterized in that the 3.75MHz SAW filter for passing the multi-FA band. In the RF transmitting apparatus of a mobile communication base station system having a plurality of channel cards for providing I / Q channel baseband signals for multiple FAs and a transmitting antenna, QPSK modulated CDMA baseband signals output from the channel cards of each FA for each FA, and then serially combine the modulated QPSK modulated signals for each FA with the QPSK modulated signals of the lower or upper FAs at the highest or lowest FA. A digital modulation unit for each of the plurality of FAs for outputting a digital modulation signal of a multi-FA band; And a D / A converter converting the combined multi-FA QPSK modulated signal output from the highest or lowest FA digital modulator into an analog signal and outputting the analog signal to an uplink converter. The analog frequency up-converting means A first uplink unit for up-converting the multi-FA combined analog modulation signal output from the D / A converter to an arbitrary intermediate frequency; A band pass filter for band-filtering the combined multi-FA intermediate frequency signal up-converted in the first upstream to an arbitrary bandwidth; And a second upstream part for converting the multi-FA intermediate frequency signal filtered by the band pass filter into a transmission RF frequency and outputting the same to a transmission part. The transmitting unit amplifies the second frequency up-converted transmission frequency signal by the analog frequency up-conversion unit to an arbitrary transmission output level, and then transmits it through the transmission antenna. . The method of claim 12, The band pass filter is a RF transmitter of a CDMA mobile communication base station system, characterized in that the 3.75MHz SAW filter for passing the multi-FA band.

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