KR20000042359A - Transmitter for reverse directional link in communication system - Google Patents

Abstract

PURPOSE: A transmitter for a reverse directional link in a communication system, is provided to supply various multimedia codes, as a max data transmit speed to be served per user is approached by 10Mbps, through transmitting data reliably to be satisfied with an error bit rate requested from each service, after estimating and compensating a channel through an optimal channel coding and a multi carrier-code division multiple access(MC-CDMA) pattern. CONSTITUTION: A transmitter for a reverse directional link in a communication system, transmits a voice traffic and a signal. The transmitter comprise a channel coder, a channel distributor(817), a modulator and synchronizer, and a upward convertor(831). The channel coder reduces a bit error rate, coding a voice traffic and signal to be transmitted. The channel coder is composed of a first signal error convertor(811), an error identifier(812), a convolution coder(813), a transmit speed synchronizer(814), and a second signal error convertor(815). The convolution coder(813) reduces an error bit rate, coding a signal delivered from the error identifier convolutedly, according to an error state value. The channel distributor(817) distributes an output signal of the channel coder by use of a specific Walsh code and pseudo noise code. The modulator and synchronizer modulates signals of a first and a second channel, which are distributed, and synchronizes a signal modulated between a user and a base station, suiting for a specific user synchronization burst signal. The upward convertor(831) converts the first and the second channel signal into a radio frequency signal upwardly, according to a specific reverse carrier signal, and counts and transmits the converted signals.

Description

Transmitter of reverse link in communication system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission apparatus for a reverse link in a communication system, and more particularly, to a transmission apparatus for transmitting voice traffic and data traffic on a reverse link using a multi carrier-code division multiple access scheme. It is about.

In general, the multiple access method is CDMA, but the signal waveform is a modulation method of the baseband signal used in a transmission apparatus of a mobile communication system that intends to implement an MC-CDMA method using an Orthogonal Frequency Division Multiple (OFDM) principle. Apply to.

However, in the conventional modulation scheme, the channel characteristics of the mobile environment are notably poor compared to the wired line, and in particular, there is a problem that the deterioration worsens as the data transmission speed increases.

Accordingly, the present invention has been made to solve the above problems, in the implementation of the reverse link transmission apparatus of the mobile communication system having a data transmission rate of 32Mbps when the frequency bandwidth is 40MHz in the millimeter wave band, The purpose of the present invention is to provide a transmission apparatus capable of stably transmitting data to satisfy an error bit rate required by each service by performing channel estimation and compensation through an optimized channel encoding and MC-CDMA scheme according to a given channel environment. have.

1 is a configuration diagram of a transmitting end of a communication system using the MC-CDMA scheme to which the present invention is applied.

2 is an explanatory diagram for a variable orthogonal spreading code of an MC-CDMA scheme to which the present invention is applied.

3 is an explanatory diagram for a data rate of the MC-CDMA system to which the present invention is applied.

4 is a schematic illustration of a speech coder to which the present invention is applied.

5 is an exemplary configuration diagram of a convolutional encoder to which the present invention is applied.

6 is an explanatory diagram of a pilot carrier applied to the present invention.

7 is a structural diagram of an inverse Fourier transform frame applied to the present invention.

8 is a configuration diagram of an embodiment of a reverse link transmission apparatus in a communication system according to the present invention.

9 is a configuration diagram of another embodiment of a reverse link transmitting apparatus in a communication system according to the present invention;

Explanation of symbols on the main parts of the drawings

811: signal error converter 812: error checker

813: convolutional coder 814: transmission rate synchronization unit

815: signal error converter 816: modulator

817: channel spreader 818, 819: serial / parallel converter

820, 821: frequency synchronization unit 822: inverse Fourier transform unit

823, 824: repeating signal insertion section 825, 826: bottle / serial conversion section

827, 828: Synchronizer 829, 830: D / A converter

831: up-conversion unit

In order to achieve the above object, the present invention provides a device for transmitting a reverse link for transmitting voice traffic and a signal in a communication system, thereby reducing a bit error rate by encoding a voice traffic and a signal to be transmitted. Channel encoding means; Channel spreading means for spreading the output signal of the channel encoding means by using a predetermined Walsh code and a pseudo noise code; Modulation and synchronization means for modulating the signals of the first and second channels spread by the channel spreading means and synchronizing the modulated signal between the user and the base station in accordance with a predetermined user synchronization burst signal; And an uplink for upconverting the signals of the first and second channels output from the modulating and synchronizing means into a high frequency signal according to a predetermined carrier signal, and adding and transmitting the uplinked high frequency signals of the first and second channels. Converting means.

The present invention also provides a reverse link transmission apparatus for transmitting data traffic and signals in a communication system, comprising: bit error correction means for correcting bit errors by encoding data traffic and signals to be transmitted; Channel encoding means for encoding a signal transmitted from said bit error correction means to reduce a bit error rate; Channel spreading means for spreading the output signal of the channel encoding means by using a predetermined Walsh code and a pseudo noise code; Modulation and synchronization means for modulating the signals of the first and second channels spread by the channel spreading means and synchronizing the modulated signal between the user and the base station in accordance with a predetermined user synchronization burst signal; And an uplink for upconverting the signals of the first and second channels output from the modulating and synchronizing means into a high frequency signal according to a predetermined carrier signal, and adding and transmitting the uplinked high frequency signals of the first and second channels. Converting means.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a block diagram of a transmitter of a communication system using the MC-CDMA scheme to which the present invention is applied, and includes multipliers 111 to 11N and 121 to 12N and adders 132 to 13N.

Where the length of the code is equal to N, the number of subcarriers c The element of is called CHIP.

Random code c Each chip of belongs to a set of {1, -1} and has a mutual orthogonal property.

That is, the following condition of [Equation 1] is satisfied.

here, δ _{i, m} silver l = m Is a value of 1, otherwise 0.

Input data symbol a _m [k] Is m Of the first user k The second bit.

MC-CDMA signal has one data symbol N Of the symbols coming in parallel i The first branch (subcarrier) is the chip, c _m [i] Multiplied by

And each subcarrier F / T _δ ( F = Integer, T _δ Spaced at regular intervals.

The transmitted signal is made up of the sum of these BRANCH outputs, and this process yields a multicarrier signal having a subcarrier containing a coded data symbol.

As shown in FIG. 1, the transmitted signal may be expressed by an equation as shown in Equation 2 below.

here, P _T (t) Is 0≤ t ≤ T It is a function that has a value of 1 in the section and a value of 0 in the other sections.

FIG. 2 is an explanatory diagram of a variable orthogonal spreading code of an MC-CDMA scheme to which the present invention is applied, and specifically defines an orthogonal spreading code used to code a data symbol in FIG. 1 and uses the orthogonal spreading code. The algorithm shows a variable orthogonal spreading code for providing various mobile multimedia service data.

Here, a Walsh-Hardamard code is used as an orthogonal spreading code, which can be generated by matrix operation.

The basic matrix unit of the Walsh-Hardamard code generation is as shown in Equation 3 below.

Using this as the base matrix, Walsh codes having a length of 2 ^m are generated by a cyclic matrix operation as shown in Equation 4 below.

Here, the matrix H _n has a size of 2 ⁿ × 2 ⁿ and is constructed using a H _n-1 matrix having a size of 2 ^n-1 × 2 ^n-1 . Each column of the matrix is given a code for each user.

Meanwhile, in order to simultaneously provide various multimedia services, it is necessary to apply a variable orthogonal spreading code.

A variable orthogonal spreading code can be generated using the aforementioned Walsh-Hardamard code, and the generation algorithm is as follows.

In this case, when the transmission rate of the service data that is the basic (lowest service data) is R bps, the data of N (ie, N = 2 ^k , where k = integer) doubled rate data thereof is allocated according to the following rule. .

If one of the I x I Walsh codes is assigned to the data of the R bps rate, the NR bps data is i-th. And The code of the first (where j = 1, 2, ..., N-1) is allocated.

Here, only the i th code is actually used.

In FIG. 2, the algorithm is described using data of R = 14.4 Kbps rate and data of 57.6 Kbps rate four times that of the example.

FIG. 3 is an explanatory diagram of a data rate of the MC-CDMA scheme to which the present invention is applied. FIG. 3 is a diagram illustrating various mobile multimedia services using the MC-CDMA scheme described with reference to FIG. 1 and the variable orthogonal spreading code described with reference to FIG. Service data is mapped to a given frequency bandwidth according to the transmission speed.

Multiband consists of 5/10/20 / 40MHz and is a unit of interchannel spacing. Given a maximum frequency bandwidth of 40 MHz, using a lowpass filter with a roll-off factor of 0.22, the maximum available frequency bandwidth is 32.768 MHz.

In addition, the service data to be provided in the present invention is set to 32K / 64K / 384K / 1M / 5M / 10Mbps, and each service data includes data for forward error correction (FEC) coding and channel estimation and compensation. In addition, it is mapped to a transmission symbol of an intermediate stage, and then assigned to each multiband through variable orthogonal spreading.

High-speed service data of 5M / 10Mbps is allocated with multicode to obtain the necessary spreading gain.

4 is a schematic illustration of a speech coder to which the present invention is applied.

Referring to FIG. 4, the response coder does not apply to voice data, and in this case, 15 information symbols are cut out from the (63, 59) response coder defined in the GALOIS FIELD GF 64 ( 48,44) A SHORTENED response encoder was used.

The primitive polynomial function of this encoder is expressed by the following [Equation 5].

p (x) = x ⁶ + x ² +1

Using the response coder as described above allows error detection and correction within two symbols.

5 is an exemplary configuration diagram of a convolutional coder to which the present invention is applied, and includes D-flip flops 411 to 418 and adders 421 and 422.

As shown in FIG. 5, convolutional coding is mainly performed at different code rates when the transmission data is voice and data, where the code rate R is '1/2'. Set to 'to use.

In addition, the constraint length K is designated as '9'.

The generated polynomial of the convolutional coder is expressed by Equation 6 and Equation 7 below.

g ₀ = x ⁸ + x ⁶ + x ⁵ + x ³ + x ² + x + 1

g ₁ = x ⁸ + x ⁷ + x ⁵ + x ⁴ + x + 1

6 is an explanatory diagram of a pilot carrier applied to the present invention, and shows a subcarrier of an inverse Fourier transform applied to the present invention.

Here, the total number of subcarriers is 512, of which pilot carriers are inserted into eight intervals and are 64 pieces, which occupy 1/8 of the total subcarriers.

In addition, the receiver uses the pilot carrier to compensate for phase offset of subcarriers caused by the fading channel, thereby adjusting frequency syncronization and used for channel estimation and compensation. .

7 is a structural diagram of an inverse Fourier transform frame applied to the present invention.

In FIG. 7, the cyclic prefix is to repeat about 48/512 of the frame to eliminate the interference between frames caused by the delay of the inverse Fourier transform frame.

8 is a configuration diagram of an embodiment of a transmitting apparatus for transmitting voice traffic and signals of a reverse link in a communication system according to the present invention.

As shown in FIG. 8, a transmission apparatus according to an embodiment of the present invention includes a signal error converter 811 for converting a burst error of an input voice traffic and a signal into a random error, and a signal error conversion. The signal transmitted from the error checking unit 812 according to the error checking unit 812 for checking an error state generated in the signal output from the unit 811 and the error state value checked by the error checking unit 812. A convolutional coder 813 for reducing the error bit rate by convolutional coding, a transmission rate synchronization unit 814 for inserting a predetermined signal into the output signal of the convolutional coder 813, and synchronizing at a speed to be transmitted; A signal error converter 815 for converting the burst error of the signal transmitted from the transmission rate synchronization unit 814 into a random error, a modulator 816 for modulating the signal transmitted from the signal error converter 815; By the modulator 816 A channel spreader 817 for spreading the modulated I-channel signal and the Q-channel signal, and a serial signal for converting the serial signals of the I-channel and Q-channel spread by the channel spreader 817 into parallel signals, respectively. Frequency synchronization units 820 and 821 for synchronizing frequencies by inserting predetermined pilot symbols and reference signals into the signals output from the parallel converters 818 and 819 and the serial / parallel converters 818 and 819, respectively. And an inverse Fourier transform unit 822 for inverse Fourier transforming the output signals of the frequency synchronization units 820 and 821, and a signal that is repeated in the signal transmitted from the inverse Fourier transform unit 823, thereby interfering with the symbols. Repetitive signal insertion units 823 and 824 for removing the signals, parallel / serial conversion units 825 and 826 for converting serial signals outputted from the repetitive signal insertion units 823 and 824 into parallel signals, respectively; The digital signal output from the parallel / serial converters 825 and 826 respectively outputs a user synchronization burst signal. Synchronization units 827 and 828 for synchronizing between the user and the base station, and D / A converters 829 and 830 for converting digital signals output from the synchronization units 827 and 828 into analog signals, respectively; And up-convert the I-channel signal and the Q-channel signal output from the D / A converters 829 and 830 into high-frequency signals, respectively, and then add and output the high-frequency signals of the up-converted I-channel and Q-channel. An up-conversion unit 831 is provided.

The channel spreader 817 multiplies the Walsh code by the multiplier 832 that multiplies the Walsh code by the signal of the I channel output from the modulator 816, and the Walsh code by multiplying the Walsh code by the Q-channel signal output from the modulator 816. Multiplier 833, a multiplier 834 for multiplying the I-channel signal output from the multiplier 832, and a pseudo noise code for the I-channel, and a Q-channel signal and the Q-channel pseudo output from the multiplier 833. Multiplier 835 for multiplying the noise code.

The up-converter 831 includes an up-converter 836 that mixes the baseband signal of the I-channel output from the D / A converter 829 with a carrier wave and up-converts it to a high frequency signal, and shifts the phase of the carrier by 90 °. An up-converter 838 for converting the baseband signal of the Q channel output from the D / A converter 829 and the carrier wave transmitted through the phase shifter 837 to up-convert And an adder 839 for adding the output signals of the up-converters 837 and a filter 840 for filtering the output signal of the adder 839 to remove noise.

The operation of the reverse link transmitting apparatus of the present invention having the above structure will be described below.

If the signal error converter 811 converts the burst error of the input voice traffic and signal into a random error to reduce the error bit rate, the error checker 812 receives the signal transmitted from the signal error converter 811. An error condition generated in step 2 is identified, which is passed to the convolutional coder 813 and then used to reduce the error bit rate.

The convolutional coder 813 reduces the error bit rate by convolutional coding the signal transmitted from the error checking unit 812 according to the error state confirmed by the error checking unit 812.

In this way, the signal encoded by the convolutional coder 813 is transmitted to the signal error converter 817 in synchronization with the speed to be transmitted through the transmission rate synchronizer 814, and then the signal error converter 817 is transferred. The bit error rate is reduced by converting the burst error of the received signal into a random error.

As such, the signals of the I channel and the Q channel having the reduced error bit rate are modulated by the quadrature phase shift keying (QPSK) method of the modulator 816 and then spread through the channel spreader 817.

In this case, the spread I-channel and Q-channel serial signals are converted into parallel signals through serial / parallel conversion units 818 and 819, and then transmitted to the frequency synchronization units 820 and 821.

The frequency synchronization units 820 and 821 adjust frequency synchronization by inserting a predetermined pilot symbol and a reference signal into the signals transmitted from the serial / parallel conversion units 818 and 819, respectively, and correcting the frequency offset. Estimates and compensates estimates.

The inverse Fourier transform unit 822 inversely transforms the signal transmitted from the frequency synchronization units 820 and 821 to generate an Orthogonal Frequency Division Multiple (OFDM) signal.

The repetitive signal insertions 823 and 824 respectively insert a repetitive signal into a signal transmitted from the inverse Fourier transform unit 823 to remove the interference between symbols. 825 and 826 are converted into serial signals and then passed to the synchronizers 827 and 828.

Subsequently, the synchronization units 827 and 828 synchronize the parallel signal output from the parallel / serial conversion units 825 and 826 between the user and the base station according to the user synchronization burst signal, and then the D / A conversion unit 829, 830 converts the digital signal output from the synchronization units 827 and 828 into an analog signal, respectively.

The baseband signals of the I and Q channels transmitted through the above-described process are up-converted into the high frequency signals through the up-conversion unit 831 and transmitted.

FIG. 9 is a block diagram of a transmission apparatus for transmitting data and signals of a reverse link in a communication system according to the present invention. As in FIG. 8, a signal error converter 811, an error checker 812, and a convolution are performed. Coder 813, baud rate synchronizer 814, signal error converter 815, modulator 816, channel spreader 817, serial / parallel converters 818, 819 And frequency synchronization units 820 and 821, inverse Fourier transform unit 822, repetitive signal insertion units 823 and 824, parallel and serial converters 825 and 826, and synchronization unit 827 and 828, D / A converters 829 and 830, and an up-converter 831.

In addition, the transmission apparatus according to another embodiment of the present invention illustrated in FIG. 9 further includes a bit error correction unit 910 for correcting a bit error by encoding a data traffic and a signal to be transmitted.

Here, the bit error correction unit 910 may use a Read Solomon coder.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the present invention provides an optimized channel encoding and channel estimation according to a given channel environment and the MC-CDMA scheme, thereby stably transmitting data to satisfy an error bit rate required for each service. The maximum possible data rate that can be serviced to the user is about 10Mbps, which can provide a variety of multimedia services ranging from digital video services such as MPEG-2.

Claims (16)

A reverse link transmission apparatus for transmitting voice traffic and a signal in a communication system, Channel encoding means for reducing a bit error rate by encoding a voice traffic and a signal to be transmitted; Channel spreading means for spreading the output signal of the channel encoding means by using a predetermined Walsh code and a pseudo noise code; Modulation and synchronization means for modulating the signals of the first and second channels spread by the channel spreading means and synchronizing the modulated signal between the user and the base station in accordance with a predetermined user synchronization burst signal; And In accordance with a predetermined carrier signal, up-converting up-converts the signals of the first and second channels output from the modulating and synchronizing means into high-frequency signals, and adding and transmitting the up-converted high-frequency signals of the first and second channels. Way Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 1, The channel encoding means, First signal error converting means for converting the burst error of the voice traffic and the signal into a random error; Error checking means for checking an error state generated in the signal output from the first signal error converting means; Error bit rate reducing means for reducing the error bit rate by convolutional coding the signal transmitted from the error checking means according to the error state value confirmed by the error checking means; Transmission rate synchronization means for inserting a predetermined signal into the output signal of the error bit rate reduction means and synchronizing at a speed to be transmitted; And Second signal error converting means for converting a burst error of the signal transmitted from the transmission rate synchronizing means into a random error Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 1, The channel diffusion means, Modulation means for modulating the signal transmitted from the channel encoding means; First multiplication means for multiplying the signal of the first channel modulated by the modulation means with the predetermined Walsh code; Second multiplication means for multiplying the signal of the second channel modulated by the modulation means with the predetermined Walsh code; Third multiplication means for multiplying the output signal of the first multiplication means and the predetermined pseudo noise code; And Fourth multiplication means for multiplying the output signal of the second multiplication means and the predetermined pseudo noise code; Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 1, The modulation and synchronization means, First modulation and synchronization means for modulating a signal of a first channel spread by the channel spreading means and synchronizing a modulated signal between a user and a base station in accordance with the predetermined user synchronization burst signal; And Second modulation and synchronization means for modulating a signal of a second channel spread by the channel spreading means and synchronizing a modulated signal between a user and a base station in accordance with the predetermined user synchronization burst signal Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 4, wherein The first modulation and synchronization means, Serial / parallel conversion means for converting the serial signal of the first channel spread by the channel spreading means into a parallel signal; Frequency synchronization means for synchronizing a frequency by inserting a predetermined pilot symbol and a reference signal into the parallel signal output from the serial / parallel conversion means; Inverse Fourier transform means for inverse Fourier transform the output signal of the frequency synchronization means; Repetitive signal insertion means for inserting a repetitive signal into a signal transmitted from said inverse Fourier transform means to remove interference between symbols; Parallel / serial conversion means for converting the parallel signal output from the repeating signal insertion means into a serial signal; Synchronization means for synchronizing the serial signal converted by the parallel / serial conversion means between the user and the base station in accordance with the user synchronization burst signal; And D / A conversion means for converting the digital signal output from the synchronization means into an analog signal and output to the up-conversion means Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 4, wherein The second modulation and synchronization means, Serial / parallel conversion means for converting the serial signal of the second channel spread by the channel spreading means into a parallel signal; Frequency synchronization means for synchronizing a frequency by inserting a predetermined pilot symbol and a reference signal into the parallel signal output from the serial / parallel conversion means; Inverse Fourier transform means for inverse Fourier transform the output signal of the frequency synchronization means; Repetitive signal insertion means for inserting a repetitive signal into a signal transmitted from said inverse Fourier transform means to remove interference between symbols; Parallel / serial conversion means for converting the parallel signal output from the repeating signal insertion means into a serial signal; Synchronization means for synchronizing the serial signal converted by the parallel / serial conversion means between the user and the base station in accordance with the user synchronization burst signal; And D / A conversion means for converting the digital signal output from the synchronization means into an analog signal and output to the up-conversion means Apparatus for transmitting the reverse link in a communication system comprising a. The method according to any one of claims 1 to 6, The upconversion means, A first up-converter configured to up-convert the signal of the first channel transmitted from the modulation and synchronization means to a high frequency signal according to the predetermined carrier signal; A phase shifter for shifting a phase of the predetermined carrier signal; A second up-converter for up-converting a signal of a second channel transmitted from the modulation and synchronization means into a high frequency signal according to a carrier signal shifted in phase by the phase shifter; An adder for adding signals of the first and second channels upconverted by the first and second upconverters; And Filtering means for removing noise by filtering the signal added by the adder Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 7, wherein The phase shift unit, And transmitting said predetermined carrier signal by substantially 90 [deg.]. In the reverse link transmission apparatus for transmitting data traffic and signals in a communication system, Bit error correction means for correcting a bit error by encoding data traffic and a signal to be transmitted; Channel encoding means for encoding a signal transmitted from said bit error correction means to reduce a bit error rate; Channel spreading means for spreading the output signal of the channel encoding means by using a predetermined Walsh code and a pseudo noise code; Modulation and synchronization means for modulating the signals of the first and second channels spread by the channel spreading means and synchronizing the modulated signal between the user and the base station in accordance with a predetermined user synchronization burst signal; And In accordance with a predetermined carrier signal, up-converting up-converts the signals of the first and second channels output from the modulating and synchronizing means into high-frequency signals, and adding and transmitting the up-converted high-frequency signals of the first and second channels. Way Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 9, The channel encoding means, First signal error converting means for converting a burst error of the signal output from the bit error correcting means into a random error; Error checking means for checking an error state generated in the signal output from the first signal error converting means; Error bit rate reducing means for reducing the error bit rate by convolutional coding the signal transmitted from the error checking means according to the error state value confirmed by the error checking means; Transmission rate synchronization means for inserting a predetermined signal into the output signal of the error bit rate reduction means and synchronizing at a speed to be transmitted; And Second signal error converting means for converting a burst error of the signal transmitted from the transmission rate synchronizing means into a random error Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 9, The channel diffusion means, Modulation means for modulating the signal transmitted from the channel encoding means; First multiplication means for multiplying the signal of the first channel modulated by the modulation means with the predetermined Walsh code; Second multiplication means for multiplying the signal of the second channel modulated by the modulation means with the predetermined Walsh code; Third multiplication means for multiplying the output signal of the first multiplication means and the predetermined pseudo noise code; And Fourth multiplication means for multiplying the output signal of the second multiplication means and the predetermined pseudo noise code; Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 9, The modulation and synchronization means, First modulation and synchronization means for modulating a signal of a first channel spread by the channel spreading means and synchronizing a modulated signal between a user and a base station in accordance with the predetermined user synchronization burst signal; And Second modulation and synchronization means for modulating a signal of a second channel spread by the channel spreading means and synchronizing a modulated signal between a user and a base station in accordance with the predetermined user synchronization burst signal Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 12, The first modulation and synchronization means, Serial / parallel conversion means for converting the serial signal of the first channel spread by the channel spreading means into a parallel signal; Frequency synchronization means for synchronizing a frequency by inserting a predetermined pilot symbol and a reference signal into the parallel signal output from the serial / parallel conversion means; Inverse Fourier transform means for inverse Fourier transform the output signal of the frequency synchronization means; Repetitive signal insertion means for inserting a repetitive signal into a signal transmitted from said inverse Fourier transform means to remove interference between symbols; Parallel / serial conversion means for converting the parallel signal output from the repeating signal insertion means into a serial signal; Synchronization means for synchronizing the serial signal converted by the parallel / serial conversion means between the user and the base station in accordance with the user synchronization burst signal; And D / A conversion means for converting the digital signal output from the synchronization means into an analog signal and output to the up-conversion means Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 12, The second modulation and synchronization means, Serial / parallel conversion means for converting the serial signal of the second channel spread by the channel spreading means into a parallel signal; Frequency synchronization means for synchronizing a frequency by inserting a predetermined pilot symbol and a reference signal into the parallel signal output from the serial / parallel conversion means; Inverse Fourier transform means for inverse Fourier transform the output signal of the frequency synchronization means; Repetitive signal insertion means for inserting a repetitive signal into a signal transmitted from said inverse Fourier transform means to remove interference between symbols; Parallel / serial conversion means for converting the parallel signal output from the repeating signal insertion means into a serial signal; Synchronization means for synchronizing the serial signal converted by the parallel / serial conversion means between the user and the base station in accordance with the user synchronization burst signal; And D / A conversion means for converting the digital signal output from the synchronization means into an analog signal and output to the up-conversion means Apparatus for transmitting the reverse link in a communication system comprising a. The method according to any one of claims 9 to 14, The upconversion means, A first up-converter configured to up-convert the signal of the first channel transmitted from the modulation and synchronization means to a high frequency signal according to the predetermined carrier signal; A phase shifter for shifting a phase of the predetermined carrier signal; A second up-converter for up-converting a signal of a second channel transmitted from the modulation and synchronization means into a high frequency signal according to a carrier signal shifted in phase by the phase shifter; An adder for adding signals of the first and second channels upconverted by the first and second upconverters; And Filtering means for removing noise by filtering the signal added by the adder Apparatus for transmitting the reverse link in a communication system comprising a. The method of claim 15, The phase shift unit, And transmitting said predetermined carrier signal by substantially 90 [deg.].