KR20020039941A - Apparatus for receiving multi-carrier signal and method thereof in mobile telecommunication system - Google Patents

Abstract

PURPOSE: An apparatus and a method for receiving a multi-carrier signal in a mobile communication system are provided to receive efficiently a multi-carrier signal including a multitude of sub carriers by improving a structure of a multi-carrier receiver. CONSTITUTION: An RF filter(311) is used for receiving an RF signal. A low noise amplifier(313) is used for amplifying the filtered signal of the RF filter(311). An image rejection filter(315) is used for removing a signal noise from the amplified signal of the low noise amplifier(313). A mixer(317) is used for mixing an output signal of the image rejection filter(315) with a sine-wave. An intermediate frequency filter(319) is used for filtering an intermediate frequency from an output signal of the mixer(317). An intermediate frequency/automatic gain control amplifier(321) is used for amplifying an output signal of the intermediate frequency filter(319). A low pass filter(323) is used for filtering an output signal of the intermediate frequency/automatic gain control amplifier(321). An A/D converter(325) is used for sampling an output signal of the low pass filter(323). A mixer(347) is used for mixing an output signal of the A/D converter(325) with the sine-wave. A down sampler(349) is used for performing a down sampling process for an output signal of the mixer(347). A digital low pass filter(350) is used for filtering an output signal of the down sampler(349). A filtered signal of the digital low pass filter(350) is outputted to a base band modem(390).

Description

Apparatus and method for receiving multicarrier signal in mobile communication system {APPARATUS FOR RECEIVING MULTI-CARRIER SIGNAL AND METHOD THEREOF IN MOBILE TELECOMMUNICATION SYSTEM}

The present invention relates to a mobile communication system, and more particularly, to a receiving apparatus and method for receiving a far carrier signal.

1 shows a spectrum of a typical multicarrier signal.

In general, the MULTI-CARRIER COMMUNICATION SYSTEM refers to a system for transmitting and receiving signals by modulating a plurality of SUBCARRIER signals having a constant bandwidth into one carrier. Thus, by transmitting and receiving a signal by forming a multicarrier signal with a plurality of subcarrier signals, the transmit / receive signal bandwidth is increased, and thus the amount of transmittable data of the transmit / receive signal is also increased. 1 illustrates a spectrum of a multicarrier signal using K subcarriers as an example. As shown in FIG. 1, the bandwidth (Band Width) of each subcarrier signal is B _S , and the total bandwidth of the multicarrier signal including K subcarrier signals having the B _S bandwidth is B _T. The multicarrier signal having a total bandwidth of B _T is transmitted to a radio frequency (RF) band having fc as a center frequency and transmitted through a wireless channel. The receiver receives the multicarrier transmitted through the receiver. Therefore, the multicarrier signal It has a valid signal component in the radio frequency band of.

A conventional receiver structure for receiving a multicarrier signal as shown in FIG. 1 will be described with reference to FIG. 2. FIG. 2 is a block diagram showing the configuration of a conventional multicarrier signal receiver. In particular, FIG. 2 is a multicarrier that performs frequency down-conversion to channelization and baseband in an analog region. A signal receiver configuration is shown.

As shown in FIG. 2, in the conventional multicarrier signal receiver, all signal processing processes ranging from RF and IF (intermediate frequency) stage signal processing, channel division, and frequency down-conversion to baseband are performed using analog devices ( It is performed by analog method using Analog Device. That is, after extracting a specific frequency band in the analog domain and transitioning to the baseband, analog-to-digital conversion is performed. First, an RF band signal received through an antenna is input to an RF filter 211. The RF filter 211 filters the signal received through the antenna in a radio frequency band and then outputs it to a low noise amplifier (LNA) 213. The low noise amplifier 213 inputs the signal output from the RF filter 211 to a low noise amplification at a preset gain ratio, and outputs the signal to an image rejection filter 215. The image component rejection filter 215 is a kind of band pass filter (BPF), and inputs a signal output from the low noise amplifier 213 and the low noise due to non-linearity of the low noise amplifier 213. The signal noise included in the output signal of the amplifier 213 is removed and output to the mixer 217. The mixer 217 mixes the signal output from the image component removing filter 215 with the SISOSOIDAL SIGNAL signal cos2 (f _c -f _IF ) t to an intermediate frequency band having a center frequency of f _IF . The shifted signal is output to an IF filter 219. The intermediate frequency filter 219 inputs an intermediate frequency signal whose center frequency output from the mixer 217 is f _IF , and filters out signal components other than the set intermediate frequency band, and then controls the intermediate frequency / auto gain. Output to an amplifier (IF / AGC (automatic gain control) Amplifier) 221. The intermediate frequency / auto gain control amplifier 221 amplifies the signal output from the intermediate frequency filter 219 to a gain set as an input and outputs the result to each subcarrier demodulation stage. In this case, the gain of the intermediate frequency / auto gain control amplifier 221 is variable in order to provide a signal having a constant amplitude to a base band modem. .

A signal input to each subcarrier signal demodulation stage, that is, a signal output from the intermediate frequency / auto gain control amplifier 221 has a bandwidth of a pass band B _S and is represented by Equation 1 below. By passing through K BPFs (band pass filters) having a center frequency as described above, each subcarrier undergoes a channelization process.

In Equation 1, Ω _k represents the center frequency of the subcarrier signal to be demodulated in each subcarrier signal demodulation stage, and k is k = 1, 2 when the number of subcarriers is a multicarrier signal composed of K. , 3, ..., K.

For convenience of explanation, the demodulation process for the k-th subcarrier signal will be described as an example. The demodulation processes for the remaining subcarrier signals also perform only the same functions except the reference numerals, and thus description thereof will be omitted.

First, the signal output from the intermediate frequency / auto gain control amplifier 221 is output to the BPF k 243, and the BPF k 243 has the passband output from the intermediate frequency / auto gain control amplifier 221 to B. Filter the signal that is _S As described in Equation 1, the BPF k 243 performs channel division for the k th subcarrier signal by performing filtering on the bandwidth B _S set with the center frequency as Ω _k . The signal output from the BPF k 243 becomes a sine wave signal and a mixing signal to separate the I (In-phase) channel signal and the Q (Quadrature) channel signal. That is, to separate the I channel signal, the signal output from the BPF k 243 is input to the mixer 245. The mixer 245 mixes the signal output from the BPF k 243 and the sine wave signal as shown in Equation 2 and outputs the LPF (Low Pass Filter) 247.

Here, Equation 2 is not applied to the sine wave signal applied only to the mixer 245, but is commonly applied to a process for separating the I channel of each of the subcarrier signal demodulation stages. In Equation 2, k is k = 1, 2, 3, ..., K when the multicarrier signal is composed of K subcarriers.

The LPF 247 filters the baseband transitioned I-channel signal output from the mixer 245 and outputs the filtered I-channel signal to an analog-to-digital converter (ADC) 249. The analog-to-digital converter 249 samples a signal output from the LPF 247 with a sampling rate of f _{s, B} and outputs it to a baseband modem 291. .

On the other hand, in order to separate the Q channel signal, the signal output from the BPF k (243) is output to the mixer 255. The mixer 255 is mixed with a signal output from the BPF k 243 and a sine wave signal as shown in Equation 3 below and output to the LPF (Low Pass Filter).

Here, Equation 3 is not applied to the sine wave signal applied only to the mixer 255, but is commonly applied to the processes for separating the Q channel of each of the subcarrier signal demodulation stages. In Equation 3, k is k = 1, 2, 3, ..., K when the multicarrier signal is composed of K subcarriers.

The LPF 257 filters the Q-channel signal shifted to the baseband output from the mixer 255 and outputs the filtered Q channel signal to an analog to digital converter (ADC) 259. The analog-to-digital converter 259 samples the signal output from the LPF 257 with a sampling rate of f _{s, B} and outputs the sampled signal to the baseband modem 291.

As described above with reference to FIG. 2, the conventional multicarrier signal receiver must be used with K BPFs in order to divide a channel of the multicarrier signal. However, these BPFs used for channel division are analog devices that occupy some space for their mounting, and are a direct obstacle to the miniaturization or integration and lightening of the system, and also increase the manufacturing cost of the system. There is a problem. In addition, because the characteristics of each device are different, in order to increase the stability and reliability of the system, it is not only necessary to perform individual inspection for each element at the time of implementation, but also to perform system-level inspection on the finally implemented system. There is a problem that there is. As shown in the figure, two analog-to-digital converters are used for the analog-to-digital conversion of the I-channel signal component and the Q-channel signal component for each subcarrier channel, thereby receiving a multicarrier signal composed of K subcarriers. A total of 2K analog-to-digital converters are required for this purpose, which also causes a problem in miniaturizing the system.

Accordingly, an object of the present invention is to provide a receiving apparatus and method for receiving a multicarrier signal composed of a plurality of subcarriers.

Still another object of the present invention is to provide a receiving apparatus and method for receiving a multicarrier signal for system miniaturization and weight reduction.

The receiving device of the present invention for achieving the above objects; Down-converting the received signal into an intermediate frequency signal to filter the baseband signal, and a digital converter for digitally sampling the filtered signal, and separating the digitally converted signal into an I-channel signal and a Q-channel signal to generate a frequency in the digital domain. And a plurality of subcarrier demodulation stages for performing down-converting.

The receiving method of the present invention for achieving the above objects; Down-converting the received signal into an intermediate frequency signal to filter the baseband signal, digitally sampling the filtered signal, and separating the digitally converted signal into an I channel signal and a Q channel signal to frequency down-convert the digital domain. Characterized in that the process is performed.

1 shows a spectrum of a typical multicarrier signal.

2 is a block diagram showing the configuration of a conventional multicarrier signal receiver.

3 is a block diagram illustrating a configuration of a multicarrier signal receiver according to an embodiment of the present invention.

4 is a block diagram showing a configuration of a multicarrier signal receiver having three subcarriers according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a multicarrier signal receiver according to an embodiment of the present invention. In particular, FIG. 3 illustrates sampling of a received signal at an intermediate frequency (IF) stage and channel division and basis in a digital domain. A multicarrier receiver configuration for performing frequency down converting to a base band is shown.

First, a signal of an RF band received through an antenna is input to an RF filter 311. The RF filter 311 filters the signal received through the antenna in a radio frequency band and outputs the low noise amplifier (LNA) 313. The low noise amplifier 313 inputs the signal output from the RF filter 311, amplifies low noise at a preset gain ratio, and outputs the signal to an image rejection filter 315. The image component rejection filter 315 is a kind of band pass filter (BPF), which receives a signal output from the low noise amplifier 313 and causes the non-linearity of the low noise amplifier 313. The signal noise included in the output signal of the low noise amplifier 313 is removed and output to the mixer 317. The mixer 317 mixes the signal output from the image component removing filter 315 with the sinusoidal signal cos2 (f _c -f _IF ) t to convert the signal transitioned to an intermediate frequency band having a center frequency of f _IF . Output to an IF filter 319. The intermediate frequency filter 319 inputs an intermediate frequency signal whose center frequency output from the mixer 317 is f _IF , filters a signal component other than the set intermediate frequency band, and then outputs an intermediate frequency / auto gain control amplifier. Output to (IF / AGC (automatic gain control) Amplifier) 321. The intermediate frequency / auto gain control amplifier 321 inputs the signal output from the intermediate frequency filter 319 and amplifies the signal to a predetermined gain and outputs the result to a low pass filter (LPF) 323. . Here, the gain of the intermediate frequency / auto gain control amplifier 321 is variable, so that it is possible to provide a signal having a constant amplitude to a base band modem. . The LPF 323 inputs the signal output from the intermediate frequency / auto gain control amplifier 321 and performs low pass filtering to output the signal to an analog-to-digital converter (ADC) 325. Here, the LPF 323 is a kind of anti-aliasing filter for preventing an aliasing phenomenon, and the pass bandwidth of the LPF 323 is B _a . The passband B _a can be expressed as follows.

The analog-to-digital converter 325 samples the signal output from the LPF 323 with a sampling rate of f _{s and IF} and outputs it to each subcarrier demodulation stage. Here, the sampling rate f _{s, IF} must be large enough so that information is not lost by analog-to-digital conversion, and for this purpose, the sampling rate f _{s, IF} must be greater than or equal to the NYQUIST SAMPLING RATE. .

A signal input to each of the subcarrier signal demodulation stages, that is, a sampled signal output from the analog-digital converter 325, is input to the K subcarrier signal demodulation stages. Since the processes performed in each of the K subcarrier signal demodulation stages are different from each other only in the reference numerals of FIG. 3, only the demodulation process for the k th subcarrier signal is used as an example for convenience of description. A detailed description of demodulation processes for the remaining subcarrier signals will be omitted.

First, the signal output from the analog-to-digital converter 325 is mixed with respective sinusoidal signals to separate an in-phase (I) channel signal and a quadrature (Q) channel signal. That is, the signal output from the analog-to-digital converter 325 is input to the mixer 347 to separate the I-channel signal. The mixer 347 mixes the signal output from the analog-to-digital converter 325 with a sine wave signal represented by Equation 4 below and outputs it to the M: 1 down sampler 349.

Here, Equation 4 is not applied to the sine wave signal applied only to the mixer 347, but is commonly applied to processes for separating the I channel of each of the subcarrier signal demodulation stages. In Equation 4, k is k = 1, 2, 3, ..., K when the multicarrier signal is composed of K subcarriers. In addition, the T _s is an inverse of the sampling rate f _{s, IF} , and n has an integer value as an index representing time.

The signal component of the I channel, which is mixed with the sinusoidal signal in the mixer 347 and transitioned to the baseband, is input to the M: 1 down sampler 349. The M: 1 down sampler 349 inputs a signal output from the mixer 347 to downsample M: 1 and outputs the digital low pass filter (LPF) 350. The digital LPF 350 inputs the signal output from the M: 1 down sampler 349, low-pass filters the signal output from the M: 1 down sampler 349, and outputs the signal to a base band modem 390. Here, the signal output from the digital LPF 350 has a narrow bandwidth compared to the signal output from the analog-to-digital converter 325. If the sampling rate is higher than necessary, power consumption increases in the baseband modem 390, thereby reducing the sampling rate through the M: 1 down sampler 349 in front of the baseband modem 390. If it is B _l bandwidth (bandwidth) of the digital LPF (350), wherein M is B _a / B equal to the _l, wherein B _a / B _l is the smallest among the not less constant than that of the B _a / B _l It means an integer. That is, the sampling rate of the output signal may be M times lower than the sampling rate of the input signal by taking only every M th sample among the signals input to the M: 1 downsampler 349 and ignoring the remaining samples.

Meanwhile, the signal output from the analog-to-digital converter 325 is input to the mixer 357 to separate the Q channel signal. The mixer 357 inputs the signal output from the analog-digital converter 325, mixes the sine wave signal represented by Equation 5, and outputs the mixed signal to the M: 1 down sampler 359.

Here, Equation 5 is not applied to the sinusoidal signal applied only to the mixer 357, but is commonly applied to the processes for separating the Q channels of each of the subcarrier signal demodulation stages. In Equation 5, k is k = 1, 2, 3, ..., K when the multicarrier signal is composed of K subcarriers. The T _s is an inverse of the sampling rate f _{s and IF} , and n has an integer value as an index representing time.

The signal component of the Q channel mixed with the sinusoidal signal in the mixer 357 and shifted to the baseband is input to the M: 1 down sampler 359. The M: 1 down sampler 359 receives the signal output from the mixer 357 as an input and outputs the M: 1 downsampler to the digital LPF 360. The digital LPF 360 inputs the signal output from the M: 1 down sampler 359, low pass filters the signal output from the M: 1 down sampler 359, and outputs the result to the base band modem 390. Here, the signal output from the digital LPF 360 has a narrow bandwidth compared to the signal output from the analog-digital converter 325. If the sampling rate is higher than necessary, power consumption increases in the baseband modem 390, thereby reducing the sampling rate through the M: 1 down sampler 359 in front of the baseband modem 390. If it is B _l bandwidth (bandwidth) of the digital LPF (360), wherein M is B _a / B equal to the _l, wherein B _a / B _l is the smallest among the not less constant than that of the B _a / B _l It means an integer. That is, the sampling rate of the output signal may be M times lower than the sampling rate of the input signal by taking only every Mth sample among the signals input to the M: 1 downsampler 359 and ignoring the remaining samples.

In FIG. 3, a process of sampling a received signal at an intermediate frequency stage and frequency downconverting the channel to the baseband and channel division in the digital domain is described. A multicarrier signal receiver structure composed of three subcarriers among the multicarrier signal receivers described with reference to FIG. 3 will be described with reference to FIG. 4.

4 is a block diagram illustrating a multicarrier signal receiver configuration consisting of three subcarriers according to an embodiment of the present invention. First, the RF filter 311, the low noise amplifier 313, the image component removing filter 315, the mixer 317, the intermediate frequency filter 319, the intermediate frequency / auto gain control filter 321 shown in FIG. Since the LPF 323 and the analog-to-digital converter 325 perform the same functions as described with reference to FIG. 3, their detailed description will be omitted. Sampled signals output from the analog-to-digital converter 325 are output to the mixer 411 and the mixer 451, respectively. An information-carrying signal including information among the signals output from the analog-digital converter 325 is represented by Equation 6 below.

s (nT _S ) = I ₁ (nT _S ) cos2π (f _IF -B _S ) nT _S + Q ₁ (nT _S ) sin2π (f _IF -B _S ) nT _S + I ₂ (nT _S ) cos2πf _IF nT _S + Q ₂ (nT _S ) sin2πf _IF nT _S + I ₃ (nT _S ) cos2π (f _IF + B _S ) nT _S + Q ₃ (nT _S ) sin2π (f _IF + B _S ) nT _S

In Equation 6, the I _k (nT _S ), k = 1, 2, 3 and Q _k (nT _S ), k = 1, 2, 3 are the I channel of the k-th subcarrier at t = nT _S It means a signal component and a Q channel signal component. In Equation 6, s (nT _S ) is input to the mixer 411 and the mixer 451 and mixed with the respective sinusoidal signals.

That is, the mixer 411 mixes the s (nT _S ) and the sinusoidal signal 2cos2? F _IF nT _S and outputs the mixed signal to the mixer 421, the mixer 431, and the M: 1 down sampler 445. Here, the output signal of the mixer 411 is shown in Equation 7 below.

2s (nT _S ) cos2πf _IF nT _S = I ₂ (nT _S ) + [I ₁ (nT _S ) + I ₃ (nT _S )] cos2πB _S nT _S- [Q ₁ (nT _S ) -Q ₃ (nT _S )] sin2πB _S nT _S + I ₁ (nT _S ) cos2π (2f _IF -B _S ) nT _S + Q ₁ (nT _S ) sin2π (2f _IF -B _S ) nT _S + I ₂ (nT _S ) cos4πf _IF nT _S + Q ₂ (nT _S ) sin4πf _IF nT _S + I ₃ (nT _S ) cos2π (2f _IF + B _S ) nT _S + Q ₃ (nT _S ) sin2π (2f _IF + B _S ) nT _S

The signal output from the mixer 411 is input to the M: 1 down sampler 445, and the M: 1 down sampler 445 is sampled every Mth among the signals output from the mixer 411. By taking only and ignoring the rest of the samples, we make the sample rate of the output signal M times lower than the sample rate of the input signal. Through this process, the M: 1 down sampler 445 outputs the M: 1 downsampled signal to the digital LPF 447, and the digital LPF 447 outputs the M: 1 down sampler 445 to the digital LPF 447. The output signal is low-pass filtered to obtain an I channel signal I ₂ for the second subcarrier.

On the other hand, the mixer 451 mixes the s (nT _S ) and the sinusoidal signal 2sin2πf _IF nT _S and outputs it to the mixer 461, the mixer 471, and the M: 1 down sampler 455. Here, the output signal of the mixer 451 is expressed by Equation 8 below.

2s (nT _S ) sin2πf _IF nT _S = Q ₂ (nT _S ) + [Q ₁ (nT _S ) + Q ₃ (nT _S )] cos2πB _S nT _S [-] [I ₁ (nT _S ) -I ₃ ( nT _S )] sin2πB _S nT _S -Q ₁ (nT _S ) cos2π (2f _IF -B _S ) nT _S + I ₁ (nT _S ) sin2π (2f _IF -B _S ) nT _S -Q ₂ (nT _S ) cos4πf _IF nT _S + I ₂ (nT _S ) sin4πf _IF nT _S -Q ₃ (nT _S ) cos2π (2f _IF + B _S ) nT _S + I ₃ (nT _S ) sin2π (2f _IF + B _S ) nT _S

The signal output from the mixer 451 is input to the M: 1 down sampler 455, and the M: 1 down sampler 455 is sampled every Mth among the signals output from the mixer 451. By taking only the sample and ignoring the remaining samples, the sampling rate of the output signal is M times lower than the sampling rate of the input signal. Through this process, the M: 1 down sampler 455 outputs the M: 1 downsampled signal to the digital LPF 457, and the digital LPF 457 outputs the M: 1 down sampler 455. The output signal is low pass filtered to obtain a Q channel signal Q ₂ for the second subcarrier.

The I channel signal I ₁ and the Q channel signal Q ₁ for the first subcarrier can be obtained by M: 1 down sampling and low pass filtering the signals shown in Equations 9 and 10, respectively, I-channel signal (I ₃₎ and the Q channel Shiho (Q ₃₎ for the subcarrier signals as shown in equation 11 and equation 12 for each M: 1 down can be determined by sampling and low-pass filtering.

I ₁ (nT _S ) => 2s (nT _S ) cos2πf _IF nT _S cos2πB _S nT _S + 2s (nT _S ) sin2πf _IF nT _S sin2πB _S nT _S

Q ₁ (nT _S ) => -2s (nT _S ) cos2πf _IF nT _S sin2πB _S nT _S + 2s (nT _S ) sin2πf _IF nT _S cos2πB _S nT _S

I ₃ (nT _S ) => 2s (nT _S ) cos2πf _IF nT _S cos2πB _S nT _S -2s (nT _S ) sin2πf _IF nT _S sin2πB _S nT _S

Q ₃ (nT _S ) => 2s (nT _S ) cos2πf _IF nT _S sin2πB _S nT _S + 2s (nT _S ) sin2πf _IF nT _S cos2πB _S nT _S

As described with reference to FIG. 4, the number of numerically controlled oscillators (NCOs) required in a multicarrier signal receiver composed of three subcarriers is a multicarrier signal composed of K subcarriers described with reference to FIG. Less than the number of numerically controlled oscillators required at the receiver. That is, since the multicarrier signal receiver composed of the three subcarriers needs to have two numerically controlled oscillators each having an output frequency of f _IF and B _S, the multicarrier having K subcarriers according to an embodiment of the present invention is provided. The carrier signal receiver is more efficient than having three numerically controlled oscillators consisting of f _IF -B _S and output frequencies of f _IF and f _IF + B _S , respectively.

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

The present invention as described above allows only one analog-to-digital signal to be sampled in the intermediate frequency band prior to channel division from the received RF signal and to perform channel division and down-conversion to baseband in the digital domain. Only digital converters are used, and BPF, an analog device, is no longer needed, which has the advantage of miniaturizing, integrating and reducing the weight of the system. Also. By reducing the number of analog devices, the system manufacturing cost is reduced, and the process of eliminating the inspection process is eliminated by eliminating the inspection process per analog device for improving system stability and reliability.

In addition, this is an SDR that modularizes each block of the system so that each module has a uniform interface, and that each module can be configured only by software to give the system maximum flexibility. This is in line with the concept of software-defined radio. In other words, in view of the signal flow inside the receiver, the received signal is sampled at the position as close as possible to the antenna, and the subsequent signal processing processes related to the air interface are processed in the digital domain, thereby reducing the weight and power of the receiver. (low power consumption) has the advantage of conforming to the concept to promote.

Claims (26)

In the signal receiving apparatus in a mobile communication system, A digital converter for down-converting the received signal into an intermediate frequency signal to filter the baseband signal, and digitally sampling the filtered signal; And a demodulation stage for dividing the digitally converted signal into an I channel signal and a Q channel signal to perform frequency down-conversion in a digital domain. The method of claim 1, The digital conversion unit; An intermediate frequency converter converting the received signal into an intermediate frequency band; And a digital sampling unit configured to filter the intermediate frequency signal into a baseband signal and then digitally sample the signal. The method of claim 1, The demodulator includes an I channel demodulator for demodulating an I channel signal among the digitally converted signals; And a Q channel demodulator for demodulating a Q channel signal among the digitally converted signals. The method of claim 3, The demodulation unit is a signal receiving device in a mobile communication system, characterized in that the number of subcarriers constituting the multicarrier signal when the received signal is a multicarrier signal. The method of claim 3, The I channel demodulator; A mixer for mixing the digitally converted signal with a sinusoidal signal having a corresponding frequency; An M: 1 down sampler for M: 1 down sampling the sine wave signal and the mixed signal having the corresponding frequency; And a digital low pass filter for digital low pass filtering the M: 1 down-sampled signal. The method of claim 5, The M: 1 down sampler takes only every Mth sampling of the output signal of the mixer and ignores the remaining samples, thereby reducing the sampling rate of the output signal by M times lower than the sampling rate of the input signal. Receiving device. The method of claim 3, The Q channel demodulator; A mixer for mixing the digitally converted signal with a sinusoidal signal having a corresponding frequency; An M: 1 down sampler for M: 1 down sampling the sine wave signal and the mixed signal having the corresponding frequency; And a digital low pass filter for digital low pass filtering the M: 1 down-sampled signal. The method of claim 7, wherein The M: 1 down sampler takes only every Mth sample of the output signal of the mixer and ignores the remaining samples so that the sampling rate of the output signal is M times lower than the sampling rate of the input signal. Receiving device. The method of claim 2, The digital sampling unit; A low pass filter for filtering the intermediate frequency signal into a baseband signal; And an analog-to-digital converter for digitally sampling the filtered signal. The method of claim 9, The analog-to-digital converter is a multi-carrier signal receiving device in a mobile communication system characterized in that the digital sampling at a sampling rate greater than or equal to the Nyquist sampling rate, so that information is not lost by the analog-to-digital conversion. In the method of receiving a multicarrier signal in a mobile communication system, Down-converting the received signal into an intermediate frequency signal to filter the baseband signal, and digitally sampling the filtered signal; And dividing the digitally converted signal into an I channel signal and a Q channel signal to perform frequency down-conversion in a frequency domain. The method of claim 11, The digital sampling process is a signal receiving method in a mobile communication system characterized in that the digital sampling at a sampling rate greater than or equal to the Nyquist sampling rate so that information is not lost by analog-to-digital conversion. The method of claim 11, The frequency down-converting process for each of the I channel signal and the Q channel signal is performed for each subcarrier constituting the multicarrier. The method of claim 11, Frequency down converting the I channel signal; Mixing the digitally converted signal with a sinusoidal signal having a corresponding frequency; Performing M: 1 down sampling on the sine wave signal having the corresponding frequency and the mixed signal; And a digital low pass filtering of the M: 1 down-sampled signal. The method of claim 14, The M: 1 down sampling process takes only every Mth sample as a result of the mixing process and ignores the remaining samples, thereby reducing the sampling rate of the down sampled signal by M times lower than the sampling rate of the signal before down sampling. Signal receiving method in mobile communication system. The method of claim 11, Frequency down-converting the Q channel signal; Mixing the digitally converted signal with a corresponding carrier; Performing M: 1 down sampling on the mixed signal with the corresponding carrier; And a digital low pass filtering of the M: 1 down-sampled signal. The method of claim 16, The M: 1 down sampling process maintains the same signal-to-noise ratio as the original received signal when demodulating from the digitally converted state to the analog state. A reception apparatus of a mobile communication system for receiving a multicarrier signal composed of three subcarriers, A digital converter for down-converting the received multicarrier signal into an intermediate frequency signal to filter the baseband signal, and digitally sampling the filtered signal; And a subcarrier demodulation stage for separating the digitally converted signal into an I channel signal and a Q channel signal to perform frequency down-conversion in the digital domain to demodulate each subcarrier. The method of claim 18, The digital conversion unit; An intermediate frequency converter converting the received signal into an intermediate frequency band; And a digital sampling unit configured to filter the intermediate frequency signal into a baseband signal and then digitally sample the signal. The method of claim 18, The subcarrier demodulation stage includes a first subcarrier demodulation stage, a second subcarrier demodulation stage, and a third subcarrier demodulation stage. The method of claim 20, The first subcarrier demodulator includes an I channel demodulator for demodulating an I channel signal, and a Q channel demodulator for demodulating a Q channel signal, wherein the I channel demodulator of the first subcarrier demodulator; A first mixer unit for mixing the digitally converted signal into a first sinusoidal wave signal and a second sinusoidal wave signal each having a corresponding frequency; A second mixer for mixing the digitally converted signal into a third sinusoidal wave signal and a fourth sinusoidal wave signal, respectively; An adder for adding outputs of the first mixer and the second mixer; An M: 1 down sampler for M: 1 down sampling the added signal; And a digital low pass filter for digital low pass filtering the M: 1 down-sampled signal. The method of claim 21, A Q channel demodulator of the first subcarrier demodulator; A third mixer configured to mix the digitally converted signal into the first sinusoidal wave signal and the fifth sinusoidal wave signal, respectively; A fourth mixer for mixing the digitally converted signal into the third sinusoidal wave signal and the sixth sinusoidal wave signal, respectively; A subtractor for subtracting the third mixer output from the fourth mixer output; An M: 1 down sampler for M: 1 down sampling the added signal; And a digital low pass filter for digital low pass filtering the M: 1 down-sampled signal. The method of claim 22, The second subcarrier demodulator includes an I channel demodulator that demodulates an I channel signal, and a Q channel demodulator that demodulates a Q channel signal, wherein the I channel demodulator of the second subcarrier demodulator; A mixer for mixing the digitally converted signal with a first sinusoidal wave having a corresponding frequency; An M: 1 down sampler for M: 1 down sampling the mixed signal; And a digital low pass filter for digital low pass filtering the M: 1 down-sampled signal. The method of claim 22, The second subcarrier demodulator includes an I channel demodulator that demodulates an I channel signal, and a Q channel demodulator that demodulates a Q channel signal, wherein the Q channel demodulator of the second subcarrier demodulator; A mixer configured to mix the digitally converted signal with a third sinusoidal wave having a corresponding frequency; An M: 1 down sampler for M: 1 down sampling the mixed signal; And a digital low pass filter for digital low pass filtering the M: 1 down-sampled signal. The method of claim 22, The third subcarrier demodulator includes an I channel demodulator for demodulating an I channel signal, and a Q channel demodulator for demodulating a Q channel signal, and an I channel demodulator of the third subcarrier demodulator; A subtractor for subtracting the output of the second mixer from the output of the first mixer; An M: 1 down sampler for M: 1 down sampling the subtracted signal; And a digital low pass filter for digital low pass filtering the M: 1 down-sampled signal. The method of claim 22, A Q channel demodulator of the third subcarrier demodulator; An adder for adding the second mixer portion and the fourth mixer portion output; An M: 1 down sampler for M: 1 down sampling the added signal; And a digital low pass filter for digital low pass filtering the M: 1 down-sampled signal.