KR20090093025A - Pilot allocation method for channel quality estimation in sc-fdma system and ofdma system, and a transmitter and a receiver for channel quality estimation using the method - Google Patents

Abstract

A pilot allocation method for channel quality estimation in SC-FDMA system and OFDMA system, and a transmitter and a receiver for channel quality estimation using the method are provided to improve whole error by preventing performance deterioration at both sides frequency. In a pilot allocation method for channel quality estimation in SC-FDMA system and OFDMA system, a plurality of pilot signals for estimating channel quality is allotted to a carrier signal by using a CAZAC sequence(Constant Amplitude Zero Auto-Correlation Sequence) of the circulation conversion form. The pilot signal is allocated to the total frequency band of the carrier signal, and the discrete Fourier transform of the carrier signal including the allocated pilot signal is performed. The total frequency band of the carrier signal which is transformed by the discrete Fourier transform is divided into a plurality of subcarrier bands.

Description

Pilot Allocation Method for Channel Quality Estimation in Single Carrier Frequency Division Multiple Access Systems and Orthogonal Frequency Division Multiple Access Systems, and Transmitters and Receivers for Channel Quality Estimation Using the Same QUALITY ESTIMATION IN SC-FDMA SYSTEM AND OFDMA SYSTEM, AND A TRANSMITTER AND A RECEIVER FOR CHANNEL QUALITY ESTIMATION USING THE METHOD}

The present invention relates to a pilot allocation method in a single carrier frequency division multiple access system and an orthogonal frequency division multiple access system, and more particularly, to a pilot allocation method for channel quality estimation of a single carrier frequency division multiple access system and an orthogonal frequency division multiple access system, And it relates to a transmitter and a receiver for channel quality estimation using the same.

3rd Generation Partnership Project (3GPP) mobile communication systems based on wideband code division multiple access (WCDMA) technology are widely deployed around the world. High Speed Downlink Packet Access (HSDPA), which can be defined as the first evolutionary step in wideband code division multiple access, provides 3GPP with a highly competitive radio access technology in the near future. However, as the demands and expectations of users and operators continue to increase and the development of competing wireless access technologies continues, new technological evolution in 3GPP is required to be competitive in the future.

One of the systems considered in 3rd generation and later systems is an Orthogonal Frequency Division Multiplexing (OFDM) system that can attenuate the effect of inter-symbol interference with low complexity. OFDM converts serially input data symbols into N parallel data symbols and transmits the data symbols on N subcarriers. Herein, the subcarriers maintain orthogonality in the frequency dimension. Each orthogonal channel experiences frequency selective fading that is independent of each other, and the interval between transmitted symbols is increased, thereby minimizing inter-symbol interference. Orthogonal Frequency Division Multiple Access (OFDMA) refers to a multiple access method for realizing multiple access by independently providing each user with a part of subcarriers available in a system using OFDM as a modulation scheme.

One of the major problems with OFDM / OFDMA is that the peak amplitude of the transmitted signal can be significantly larger than the average amplitude. This Peak-to-Average Power Ratio (PAPR) problem is due to the fact that the OFDM signal is a superposition of N sinusoidal signals on different subcarriers. In order to save transmission power, it is necessary to lower the PAPR.

One system proposed to lower PAPR is Single Carrier-Frequency Division Multiple Access (SC-FDMA). SC-FDMA combines frequency division multiple access (FDMA) with the existing SC-FDE (Single Carrier-Frequency Division Equalization) scheme. SC-FDMA has similar characteristics to orthogonal frequency division multiple access in that it uses the Discrete Fourier Transform (DFT) to demodulate and demodulate the signal in the time and frequency domains. It is advantageous. In particular, it can be said that it is advantageous to the uplink accessing the base station from the terminal sensitive to the transmission power in relation to the use of the battery.

In order to efficiently restore data at the receiver, channel estimation for data demodulation and channel quality estimation for frequency selective scheduling must be efficiently performed. In general, channel estimation and channel quality estimation are performed by pilots included in a signal transmitted from a transmitter. However, the efficient pilot structure for channel quality estimation in SC-FDMA and OFDMA is not well known.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and a first object of the present invention is to estimate channel quality in SC-FDMA and OFDMA systems in order to improve not only the efficient use of the frequency band but also the synchronous demodulation performance of the receiver. The present invention provides a pilot allocation method and a transmitter / receiver using the same.

Another object of the present invention is to provide a pilot allocation method for improving the demodulation performance of a receiver between a single carrier frequency division multiple access system and a plurality of terminals of an orthogonal frequency division multiple access system and a transmitter / receiver using the same. .

In the single carrier frequency division multiple access system and the orthogonal frequency division multiple access system according to the first aspect of the present invention, a pilot allocation method for channel quality estimation in the time domain, CAZAC sequence of cyclic transform type Assigning a plurality of pilot signals for channel quality estimation to a carrier signal using a constant amplitude zero auto-correlation sequence, performing a discrete Fourier transform (DFT) on the carrier signal assigned the pilot signal, and the discrete And dividing an entire frequency band of the Fourier transformed carrier signal into a plurality of subcarrier bands.

In the time domain, the step of allocating a plurality of pilot signals for channel quality estimation to a carrier signal using a CAZAC sequence of a cyclic transform type is to assign the pilot signals in all frequency bands of the carrier signal.

In the single carrier frequency division multiple access system and the orthogonal frequency division multiple access system according to the second aspect of the present invention, a pilot allocation method for channel quality estimation is performed in a time domain in the form of a constant amplitude zero auto-correlation sequence in the form of a cyclic transform. Assigning a plurality of pilot signals for channel quality estimation to a carrier signal transmitted by the plurality of terminals, performing a discrete Fourier transform (DFT) on the carrier signal assigned the pilot signal, and the discrete And dividing the Fourier transformed carrier signal into a plurality of subcarrier bands, wherein the carrier signals transmitted by the plurality of terminals maintain orthogonality in the plurality of subcarrier bands.

In addition, in the single carrier frequency division multiple access system and the orthogonal frequency division multiple access system according to the present invention, a transmitter for channel quality estimation is assigned a pilot signal for channel quality estimation using a CAZAC sequence in the form of a cyclic transform in a time domain. A discrete Fourier transform unit (DFT) for converting a carrier signal into a frequency domain signal, a subcarrier mapper for dividing an entire frequency band of the carrier signal converted into the frequency domain signal into a plurality of subcarrier bands, and a plurality of subcarrier bands An inverse fast Fourier transform unit (IFFT) converts a carrier signal into a time domain signal and transmits the converted signal.

Here, the length of the CAZAC sequence is characterized in that it corresponds to the entire frequency band of the carrier signal.

In addition, a receiver for channel quality estimation in a single carrier frequency division multiple access system and an orthogonal frequency division multiple access system according to the present invention includes a pilot signal and converts a carrier signal transmitted by being divided into a plurality of subcarrier bands into a frequency domain signal. A fast Fourier transform unit (FFT), a subcarrier demapper for recovering a carrier signal divided into a plurality of subcarrier bands from the signal converted into the frequency domain, and a pilot signal and a reference of each subcarrier band included in the recovered carrier signal A correlator performing correlation with a pilot signal, and a channel quality estimator estimating a quality of a communication channel based on the correlation result.

According to the present invention configured as described above, a pilot allocation method for channel quality estimation and a transmitter / receiver using the same in a single carrier frequency division multiple access system and an orthogonal frequency division multiple access system according to the present invention, both end frequency bands in channel quality estimation The performance degradation does not occur in the system, and the overall error rate performance is improved. Therefore, the present invention has an advantageous effect in frequency scheduling required for efficient frequency band use and synchronous demodulation performance improvement.

1 is an exemplary view showing a mobile communication system;

2 is a block diagram showing a transmitter of an SC-FDMA system according to an embodiment of the present invention;

3 is a block diagram showing a transmitter of an OFDMA system according to an embodiment of the present invention;

4 is an exemplary view showing a signal structure of a CDM method;

5 is a block diagram showing a CDM receiver in an SC-FDMA system;

6 is a block diagram showing a CDM receiver in an OFDMA system;

7 is an exemplary view showing a pilot signal generation method according to an embodiment of the present invention;

8 is an exemplary diagram illustrating a subcarrier allocation method for multiple terminals according to an embodiment of the present invention;

9 is a block diagram illustrating a receiver of an SC-FDMA system according to an embodiment of the present invention;

10 is a block diagram showing a receiver of an OFDMA system according to an embodiment of the present invention;

11 is a flowchart illustrating a pilot signal allocation method in an SC-FDMA system and an OFDMA system according to an embodiment of the present invention;

12 is a flowchart illustrating an operation of a receiver for channel quality estimation in an SC-FDMA system and an OFDMA system according to an embodiment of the present invention;

13 is a graph comparing channel quality estimation performance for each subband,

14 is a graph comparing error rate performance according to estimating channel quality.

<Explanation of Signs of Major Parts of Drawings>

210: Discrete Fourier Transformation Unit 220: Subcarrier Mapper

230: reverse fast Fourier transform unit 240: CP insertion unit

580: CIR estimator 585: window portion

950: subcarrier demapper 960: channel estimator

990: correlator 995: channel quality estimator

Hereinafter, with reference to the accompanying drawings will be described specific details and embodiments of the present invention. Like numbers refer to like elements throughout.

1 is an exemplary diagram illustrating a mobile communication system.

Referring to FIG. 1, a mobile communication system includes a base station (BS) 110 and a plurality of terminals 120 (user equipment; UE). This may be an SC-FDMA system. Mobile communication systems are widely deployed to provide various communication services such as voice and packet data.

The base station 110 generally refers to a fixed station that communicates with the terminal 120, and in other terms, such as a node-B, a base transceiver system (BTS), an access point, and the like. Can be called.

The terminal 120 may be fixed or mobile and may be referred to by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), and a wireless device.

Hereinafter, downlink means communication from the base station 110 to the terminal 120, and uplink means communication from the terminal 120 to the base station 110. In downlink, the transmitter may be part of the base station 110 and the receiver may be part of the terminal 120. In uplink, the transmitter may be part of the terminal 120 and the receiver may be part of the base station 110. Base station 110 may include multiple receivers and multiple transmitters, and terminal 120 may include multiple receivers and multiple transmitters.

2 is a block diagram showing the configuration of a transmitter of an SC-FDMA system according to an embodiment of the present invention.

Referring to FIG. 2, the transmitter 200 includes a discrete Fourier transform unit (DFT) 210, a subcarrier mapper 220, an inverse fast Fourier transform unit (IFFT) 230, and a CP insert unit (Cyclic Prefix Insert Unit); 240).

The discrete Fourier transform unit 210 performs a discrete Fourier transform on the input signal x [n] to convert the frequency domain signal X [k]. A discrete Fourier transform process of size L may be represented by Equation 1 below.

The subcarrier mapper 220 allocates the frequency domain signal X [k] to each subcarrier by various signal structure schemes. A signal structure method allocated by the subcarrier mapper 220 will be described later.

The inverse fast Fourier transform unit 230 performs an inverse fast Fourier transform on the signal X '[k] allocated by the subcarrier mapper 220 and converts the time domain signal s [n]. The CP inserting unit 240 inserts a CP into the time domain signal s [n], which is converted into an analog signal by the RF unit 250 and propagated through the antenna 260 to the radio channel.

3 is a block diagram showing the configuration of a transmitter of an orthogonal frequency division multiple access system according to an embodiment of the present invention.

Referring to FIG. 3, the transmitter 300 includes a subcarrier mapper 310, an inverse fast Fourier transform unit 320, and a CP inserter 330.

The subcarrier mapper 310 allocates the frequency domain signal X [k] to each subcarrier by various signal structure schemes. A signal structure method allocated by the subcarrier mapper 310 will be described later.

The inverse fast Fourier transform unit 320 performs an inverse fast Fourier transform on the signal X '[k] allocated by the subcarrier mapper 310 and converts the time domain signal s [n]. The CP inserting unit 330 inserts a CP into the time domain signal s [n], which is converted into an analog signal by the RF unit 340 and propagated through the antenna 350 to the radio channel.

Meanwhile, a plurality of terminals 120 may be connected to one base station 110. Hereinafter, the number of terminals 20 is referred to as M. The base station 110 allocates time / frequency resources for each terminal 120. In order for each terminal 120 to distinguish a transmitted / received signal, a frequency resource (or subcarrier) allocated to each terminal 120 should have orthogonality. Orthogonality is time domain orthogonality, frequency domain orthogonality, or code domain orthogonality. The time domain orthogonality has a problem in that accurate transmission timing control is required. Therefore, in the single carrier frequency division multiple access system and the orthogonal frequency division multiple access system, frequency domain orthogonality and code domain orthogonality have better characteristics.

Frequency domain orthogonality may be achieved by transmitting signals through different subcarriers for each terminal. Frequency bands allocated to subcarriers do not overlap each other. Frequency domain orthogonality can be applied to local signal structures. The local signal refers to occupying a continuous spectrum. Hereinafter, a signal structure using the local signal is referred to as frequency division multiplexing-localized (FDM-L).

Frequency domain orthogonality is not suitable for channel quality estimation of the entire frequency band. That is, since subcarriers are allocated differently for each terminal, it is difficult to estimate channel quality experienced by subcarriers of other terminals.

On the other hand, code region orthogonality is achieved by transmitting a signal through a common subcarrier for each terminal. Some or all of the frequency bands allocated to the subcarriers overlap each terminal. Hereinafter, a signal structure using signals orthogonal in the code domain will be referred to as code division multiplexing (CDM).

4 is an exemplary diagram illustrating a reference signal structure of a code division multiplexing scheme.

Referring to FIG. 4, subcarriers of a pilot signal are transmitted to each other for M users (terminals). A guard band is set in frequency bands at both ends of all frequency bands that can be transmitted in a general single carrier frequency division multiple access system and an orthogonal frequency division multiple access system. Due to the setting of the guard band, the length of a constant amplitude zero auto-correlation sequence (CAZAC) that forms a subcarrier of a reference signal in a code division multiplexing scheme is set to a value smaller than the total available size.

The subcarriers of the reference signal are allocated over the entire band so that the frequency bands overlap each other. The subcarrier of the reference signal maintains orthogonality in the code region for each terminal. Through this, each terminal extracts a pilot corresponding to itself from the reference signal.

In one embodiment, the pilot signal may be orthogonal in the code region using a CAZAC sequence in the form of a cyclic shift. When L is a positive integer and k is a prime value compared to L, the n-th entry of the k-th CAZAC sequence may be expressed by Equation 2 below. Where L is the length of the CAZAC sequence and k is the sequence index.

In another embodiment, the pilot signal may be orthogonal in the code domain using a block sequence. Examples of block sequences are described in S. Zhou, et al., "Chip-Interleaved Block Spread Code Division Multiple Access", IEEE Trans. on Commun., vol. 50, no. 2, pp. 235-248, Feb. See 2002.

In the code division multiplexing scheme, the pilot signal carried on the reference signal is transmitted over the entire frequency band and thus can be used as a CQ pilot for channel quality estimation.

5 is a block diagram illustrating a configuration of a receiver of a code division multiplexing scheme in a single carrier frequency division multiple access (SC-FDMA) system.

Referring to FIG. 5, the receiver 500 includes a fast Fourier transform (FFT) 540, a subcarrier demapper 550, an inverse discrete Fourier transform (IDFT) 570, a CIR estimator 580, and a channel quality estimator 595. ).

The signal received by the antenna 510 becomes a digitized signal via the RF unit 520. In the digitized signal, the CP is removed by the CP removing unit 530. The time domain signal y [n] from which the CP is removed is transformed into the frequency domain signal Y '[k] by performing the fast Fourier transform by the fast Fourier transform unit 540. Here, the magnitude of the fast Fourier transform is N. The converted signal Y '[k] becomes the signal Y [k] by the subcarrier demapper 550 through the reverse process of the subcarrier allocation scheme.

The code division multiplexing scheme estimates channel quality using channel impulse response (CIR) in the time domain ([1] Van De Beek, Edfors O., Sandell M Wilson SK and Borjesson PO, "On channel". estimation in OFDM systems, "VTC, pp. 815-819, 1995). The CIR estimator 580 estimates the CIR h [τ] from the time domain pilot signal. When the reference signal among the received signals is r [n], CIR is obtained by using a cyclic correlation operation as shown in Equation 3 below.

Here, mod represents a modulo operation. s [n] is a time-domain pilot signal at the transmitter 200 and is a value previously known to the receiver 500.

The window portion 585 performs windowing as shown in Equation 4 below for the CIR.

That is, the window portion 585 replaces a portion excluding a predetermined region in CIR h [τ] with zero.

The fast Fourier transform unit 590 performs a fast Fourier transform on the windowed CIR and converts it into a frequency domain channel.

The channel quality estimator 595 estimates the channel quality from the pilot signal of the reference signal. By obtaining the estimated channel at each subcarrier position, the channel quality for the entire frequency band can be obtained.

In the code division multiplexing scheme, as the number of terminals increases, the windowing interval decreases, and thus, when the windowing interval is smaller than the delay spread due to the multipath, accurate CIR estimation is difficult, resulting in degradation of channel estimation and channel quality estimation. Can be. In addition, the guard band may cause degradation of channel estimation and channel quality estimation at both ends of the entire frequency.

6 is a block diagram illustrating a configuration of a receiver of a code division multiplexing scheme in an orthogonal frequency division multiple access system.

Referring to FIG. 6, the receiver 600 includes a fast Fourier transform (FFT) 640, a subcarrier demapper 650, a CIR estimator 670, and a channel quality estimator 685.

The signal received by the antenna 610 becomes a digitized signal via the RF unit 620. In the digitized signal, the CP is removed by the CP remover 630. The time domain signal r [n] from which the CP has been removed is transformed into the frequency domain signal Y '[k] by performing the fast Fourier transform by the fast Fourier transform unit 640. Here, the magnitude of the fast Fourier transform is N. The converted signal Y '[k] becomes the signal Y [k] by the subcarrier demapper 650 through the reverse process of the subcarrier allocation scheme.

Like the SC-FDMA system, the channel quality estimator 685 estimates the CIR through Equations 3 and 4, and then obtains the channel quality for the entire frequency band using the frequency domain channel converted through the FFT.

In the orthogonal frequency division multiple access system, as in the single carrier frequency division multiple access system, in the case of code division multiplexing, as the number of terminals increases, the windowing interval decreases so that the windowing interval becomes smaller than the delay spread due to the multipath. In this case, it is difficult to accurately estimate the CIR, which may cause deterioration of channel estimation and channel quality estimation. In addition, the guard band may cause degradation of channel estimation and channel quality estimation at both ends of the entire frequency.

7 is an exemplary diagram illustrating a pilot allocation method of each subband for one user (terminal) according to an embodiment of the present invention.

Referring to FIG. 7, the reference signal is divided into a plurality of sub bands in all frequency bands, and different pilots are allocated. The pilot of each subband may be allocated using a CAZAC sequence or a block sequence in the form of a cyclic transform in the time domain before the discrete Fourier transform. In one embodiment of the invention, the CAZAC sequence is generated by a CAZAC sequence generator (not shown) inside the transmitter or by a CAZAC sequence generation server (not shown).

8 is an exemplary view illustrating a subcarrier allocation method in a plurality of terminals according to an embodiment of the present invention.

Referring to FIG. 8, each terminal is allocated to an overlapping frequency band, and each subcarrier has orthogonality in a code region through a cyclic transform form in the same frequency domain.

9 is a block diagram showing the configuration of a receiver in a single carrier frequency division multiple access system according to an embodiment of the present invention.

Referring to FIG. 9, the receiver 900 includes a fast Fourier transform unit 940, a subcarrier demapper 950, a channel estimator 960, an inverse discrete Fourier transform unit IDFT 980, and a channel quality estimator 995. ).

The signal received by the antenna 910 becomes a digitized signal via the RF unit 920. In the digitized signal, the CP is removed by the CP removing unit 930. The time domain signal y [n] from which the CP is removed is converted into the frequency domain signal Y '[k] by the fast Fourier transform unit 940. The converted signal Y '[k] becomes the signal Y [k] by the subcarrier demapper 950 through the reverse process of the subcarrier allocation scheme. Then, using the estimated channel H [k], equalizer 970 compensates for the data signal. The inverse discrete Fourier transform unit 980 performs an inverse discrete Fourier transform on the compensated signal X [k] and converts it into a time domain signal x [n].

On the other hand, when a reference signal for channel quality estimation is received, channel quality estimation is performed by performing correlation for each subband for the CQ pilot R [k] in the frequency domain. The correlator 990 performs a correlation between the pilot signal of each subband included in the frequency domain signal recovered by the subcarrier demapper 950 and the reference pilot signal, and the channel quality estimator 995 performs an analysis on each subband. The channel quality is estimated based on the correlation result. Here, if the subband size is N _sub , the estimation process of each subband channel quality CQ _i may be represented by Equation 5.

Here, S _i is a frequency-domain pilot signal for each subband in the transmitter 200 and is a value previously known to the receiver 900.

10 is a block diagram showing the configuration of a receiver in an orthogonal frequency division multiple access system according to an embodiment of the present invention.

Referring to FIG. 10, the receiver 1000 includes a fast Fourier transform unit 1040, a subcarrier demapper 1050, a channel estimator 1060, and a channel quality estimator 1085.

The signal received by the antenna 1010 becomes a digitized signal via the RF unit 1020. In the digitized signal, the CP is removed by the CP remover 1030. The time domain signal y [n] from which the CP is removed is converted into the frequency domain signal Y '[k] by the fast Fourier transform unit 1040. The converted signal Y '[k] becomes the signal Y [k] by the subcarrier demapper 1050 through the reverse process of the subcarrier allocation scheme. The equalizer 1070 compensates for the data signal using the estimated channel H [k].

On the other hand, when a reference signal for channel quality estimation is received, the channel quality estimation is performed by correlating each subband with respect to the CQ pilot R [k] in the frequency domain as in the SC-FDMA system. The correlator 1080 performs a correlation between the pilot signal of each subband included in the frequency domain signal recovered by the subcarrier demapper 1050 and the reference pilot signal, and the channel quality estimator 1085 for each subband. The channel quality is estimated based on the correlation result. Similarly, the estimation process of each subband channel quality CQ _i can be expressed as Equation 5.

11 is a flowchart illustrating a method for allocating a pilot signal for channel quality estimation using the CAZAC sequence of the present invention. The method begins with assigning a plurality of pilot signals for channel quality estimation to a carrier signal (S1120) using a CAZAC sequence in the form of a cyclic transform in the time domain. Subsequently, a discrete Fourier transform (DFT) of the carrier signal to which the pilot signal is assigned is performed (S1140). Thereafter, the entire frequency band of the discrete Fourier transform carrier signal is divided into a plurality of subcarrier bands and transmitted (S1140).

12 is a flowchart illustrating operation of a receiver for channel quality estimation in a single carrier frequency division multiple access system (SC-FDMA) and an orthogonal frequency division multiple access system (OFDMA) of the present invention.

First, in step S1220, a carrier signal divided into a plurality of subcarrier bands including a pilot signal and transmitted is converted into a frequency domain signal. Thereafter, the carrier signal divided into the plurality of subcarrier bands is recovered from the signal converted into the frequency domain in step S1240. Thereafter, in step S1260, a correlation between the pilot signal of each subcarrier band included in the recovered carrier signal and the reference pilot signal is performed. In step S1280, the quality of the communication channel is estimated based on this correlation result.

13 is a graph comparing channel quality estimation performance for each subband. In order to compare the channel quality estimation performance of each signal structure, the mean square error (MSE) performance according to SNR is shown. The simulation was performed by recording statistical performance figures through a sufficient number of iterations in randomly changing wireless channels and AWGN (Additive White Gaussian Noise) environments. The radio channel model is based on the COST 207 TU (Typical Urban), which is a mathematical representation of the radio channel situation in a real urban environment. Since each performance evaluation is only for evaluating the quality estimation performance of the channel, the synchronization of the receiver is assumed to be perfect.

Referring to FIG. 13, since the signal structure according to the present invention estimates only channel quality through correlation in the frequency domain for each subband, MSE performance deteriorates in the remaining bands except for both end frequency bands when compared to the code division multiplexing scheme. You can see that. However, in both frequency bands, MSE performance is lower than code division multiplexing, that is, a small error rate. Accordingly, it can be seen that the degradation of the channel quality estimation performance is improved in both the left and right frequency bands caused by the presence of the guard band.

14 is a graph comparing error rate performance according to estimating channel quality. It shows performance of evaluating whether accurate channel quality is estimated for each subband.

Referring to FIG. 14, the signal structure according to the present invention exhibits lower error rate performance, that is, more accurate channel quality estimation performance, than code division multiplexing. Therefore, it can be seen that the overall channel quality estimation performance is improved.

The proposed signal structure is a structure in which a specific reference signal is used only for quality estimation of a channel, and shows better channel quality estimation performance in both left and right frequency bands of the entire frequency band than in code division multiplexing.

The invention can be implemented in hardware, software or a combination thereof. In hardware implementation, an application specific integrated circuit (ASIC), a digital signal processing (DSP), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, and a microprocessor are designed to perform the above functions. , Other electronic units, or a combination thereof. In addition, in the software implementation, it may be implemented as a module for performing the above-described function. The software may be stored in a memory unit and executed by a processor. The memory unit or processor may employ various means well known to those skilled in the art.

Although the present invention has been described above with reference to the embodiments, it will be apparent to those skilled in the art that the present invention may be modified and changed in various ways without departing from the spirit and scope of the present invention. I can understand.

Claims (7)

In a time domain, assigning a plurality of pilot signals for channel quality estimation to a carrier signal using a constant amplitude zero auto-correlation sequence (CAZAC); Performing a discrete Fourier transform (DFT) on the carrier signal to which the pilot signal is assigned; And And a third step of dividing and transmitting the entire frequency band of the discrete Fourier transformed carrier signal into a plurality of subcarrier bands and a pilot allocation method for channel quality estimation in a single carrier frequency division multiple access system and an orthogonal frequency division multiple access system. The method of claim 1, The first step is a pilot allocation method for channel quality estimation in a single carrier frequency division multiple access system and orthogonal frequency division multiple access system, characterized in that for allocating the pilot signal in the entire frequency band of the carrier signal. In the pilot allocation method for channel quality estimation between a single carrier frequency division multiple access system and an orthogonal frequency division multiple access system between a plurality of terminals, In a time domain, allocating a plurality of pilot signals for channel quality estimation to a carrier signal transmitted by the plurality of terminals using a constant amplitude zero auto-correlation sequence (CAZAC) in a cyclic transform form; Performing Discrete Fourier Transform (DFT) on the carrier signal to which the pilot signal is assigned; And And dividing and transmitting the discrete Fourier transformed carrier signal into a plurality of subcarrier bands. Here, the carrier signal transmitted by the plurality of terminals maintains orthogonality in a plurality of subcarrier bands, the pilot allocation method for channel quality estimation in a single carrier frequency division multiple access system and orthogonal frequency division multiple access system. A discrete Fourier transform unit (DFT) for converting a carrier signal assigned a pilot signal for channel quality estimation into a frequency domain signal using a CAZAC sequence in a cyclic transform form in a time domain; A subcarrier mapper dividing an entire frequency band of the carrier signal converted into the frequency domain signal into a plurality of subcarrier bands; And For channel quality estimation in a single carrier frequency division multiple access system and an orthogonal frequency division multiple access system including an inverse fast Fourier transform unit (IFFT) for converting and transmitting a carrier signal divided into a plurality of subcarrier bands into a time domain signal transmitter. The method of claim 4, wherein The length of the CAZAC sequence is a full frequency band of the carrier signal, the transmitter for channel quality estimation in a single carrier frequency division multiple access system and orthogonal frequency division multiple access system. A fast Fourier transform unit (FFT) including a pilot signal and converting a carrier signal, which is divided into a plurality of subcarrier bands, into a frequency domain signal; A subcarrier demapper for recovering a carrier signal divided into a plurality of subcarrier bands from the signal converted into the frequency domain; A correlator for performing correlation between a pilot signal of each subcarrier band included in the recovered carrier signal and a reference pilot signal; And A receiver for channel quality estimation in a single carrier frequency division multiple access system and an orthogonal frequency division multiple access system comprising a channel quality estimator for estimating the quality of a communication channel based on the correlation result. The method of claim 6, The receiver for the channel quality estimation further comprises a channel estimator for estimating each subband channel from the carrier signal recovered by the subcarrier demapper and an orthogonal frequency division multiple access system. Receiver for estimating channel quality.