KR20070091755A - System and Verification Method for Verifying Multiple I / O-FM - Google Patents

Abstract

The present invention is for verifying the quality of data transmitted / received by A / D conversion by MIMO-OFDM. To this end, the present invention provides a WiBro process by separating and transforming the converted data by accessing MIMO OFDM. A data loading unit for generating data in the form of a data, a transmission verification unit for modulating and verifying the loaded data through QPSK, 16QAM, and 64QAM modulation schemes and gray code mapping rules, and outputting them through an output means; A MIMO channel estimator for estimating the loaded data channel for each uplink / downlink frame and outputting the output data through the output means, restoring the symbol timing of the loaded data, estimating the frequency offset, and analyzing the data quality. It includes a reception verification unit for outputting. Therefore, it is possible to analyze the signal quality of the MIMO-OFDM system, verify the MIMO channel, verify the performance of the multi-system that is difficult to implement off-line, and to update various antenna systems through software update. Applicable effect.

Description

MIMO-OFDM VERIFICATION SYSTEM AND ITS METHOD}

1 is a block diagram of a system for verifying MIMO-OFDM according to the present invention;

2 is a view showing in detail the data loading unit shown in FIG.

3 is a diagram according to a mapping rule of gray code of QPSK, 16QAM, 64QAM according to the present invention;

4 is a view showing a vertical frame structure according to the present invention,

5 illustrates a channel estimation method using interpolation in a downlink PUSC channel structure according to the present invention;

6 illustrates a channel estimation method using interpolation in an uplink PUSC channel structure according to the present invention;

7 is a view showing in detail the reception verification unit shown in FIG.

8 is a diagram for recovering timing using a double sliding window technique according to the present invention;

FIG. 9 illustrates a preamble and a first data symbol in a WiBro frame in which a cyclic prefix is inserted according to the present invention; FIG.

10 is a block diagram of frequency offset estimation using a cyclic prefix according to the present invention;

11 is a diagram for obtaining the magnitude of an error vector through a difference between an ideal signal vector and a signal vector affected by noise according to the present invention.

<Description of the symbols for the main parts of the drawings>

101: MIMO-OFDM block 103: verification system

1031: data loading section 10311: connection section

10313: decimal conversion unit 10315: separation unit

10317: reward converting unit 10319: data generating unit

1033: transmission verification unit 1035: MIMO channel estimation unit

1037: reception verification unit 10371: symbol timing recovery unit

10373: frequency offset estimator 10375: data quality analyzer

105: output means

S1: TCP / IP

The present invention relates to a system for verifying Multi-In Multi-Out (MIMO) -Orthogonal Frequency Division Modulation (OFDM) and a method of verifying the same. More particularly, the present invention relates to analog by MIMO-OFDM. The present invention relates to a system capable of verifying the quality of data transmitted / received through analog / digital (A / D) conversion and a verification method thereof.

Recently, MIMO means an antenna system capable of multiple inputs and outputs. This MIMO enables two antennas to operate at the same time for high speed data exchange.

In other words, MIMO is a technology used in Wibro, a portable Internet service. To use this technology, both the access point and the wireless LAN card must support MIMO to communicate with each other.

On the other hand, OFDM is a digital modulation scheme for multiplexing orthogonal carrier signals to avoid the use of high-speed equalizers, to reduce multi-path fading and pulsed noise, and to make full use of available bandwidth. That is, as one type of multi-carrier transmission, a single data stream is transmitted using multiple carriers of low data rate.

The aforementioned MIMO-OFDM is referred to as a multiple antenna and an orthogonal frequency multiplexing technique, and has been in the spotlight as the communication technology is rapidly developed.

However, the MIMO-OFDM is in a state of incomplete technology development even though a verification tool is necessary to verify the operation state of the internal system by itself.

Accordingly, the method of using a plurality of instruments capable of verifying each channel individually is the only method for verifying the MIMO-OFDM system, but considering the rapidly developing environment of semiconductor and information communication technology, There is a need to be developed with various verification methods according to the development of hardware and software tools that can easily identify the state.

Accordingly, the present invention has been made in view of the necessity as described above, an object thereof is a system for verifying the MIMO-OFDM capable of verifying the quality of the transmission / reception data subjected to the A / D conversion by MIMO-OFDM and The verification method is provided.

A system for verifying MIMO-OFDM according to an aspect of the present invention for achieving the above object is a data loading to generate data in the form of WiBro through the process of separating and transform loading the converted data by accessing MIMO OFDM A transmission verification unit that modulates and verifies by applying the data, which has been loaded, and the loading process to QPSK, 16QAM, 64QAM modulation schemes and gray code mapping rules, and outputs them through output means, and the loaded data channel up / down link And a MIMO channel estimator for estimating each frame and outputting the data through an output means, and a reception verification unit for restoring symbol timing of the loaded data, estimating a frequency offset, and analyzing the data quality and outputting the data through the output means. It is done.

In addition, the method for verifying the MIMO-OFDM according to another aspect of the present invention for achieving the above object is generated by the WiBro form of the data by accessing the MIMO OFDM separated and transform loading process And a second process of modulating and verifying the loaded data through QPSK, 16QAM, and 64QAM modulation schemes and gray code mapping rules, and outputting them through an output means. A third process of estimating the uplink / downlink frame for each output frame and outputting it through the output means, and a fourth process of restoring symbol timing of the loaded data, estimating frequency offset, analyzing the data quality, and outputting the output signal through the output means. It is characterized by including.

Hereinafter, a plurality of embodiments of the present invention may exist, and a preferred embodiment will be described in detail with reference to the accompanying drawings. Those skilled in the art will appreciate the objects, features and advantages of the present invention through this embodiment.

1 is a block diagram of a system for verifying MIMO-OFDM according to the present invention, which includes a MIMO-OFDM block 101, a verification system 103, and an output means 105.

The MIMO-OFDM block 101 is a technology used for Wibro, a portable Internet service, and is a digital modulation method for multiplexing orthogonal carrier signals, thereby avoiding the use of a high-speed equalizer and multi-path fading. It not only reduces the noise and pulse type noise but also provides the demodulation block (not shown) with transmit / receive data modulated by A / D conversion on the input / receive signal input while using the available band. The transmission / reception data is provided to the verification system 103 to verify the transmission / reception data.

The verification system 103 is a block for verifying transmission / reception data provided by A / D conversion by the MIMO-OFDM block 101, and includes a data loading unit 1031, a transmission verification unit 1033, and a MIMO channel. An estimator 1035 and a reception verifyer 1037.

The data loading unit 1031 is A / D-converted by the MIMO-OFDM block 101 and received for each antenna by transmission control protocol / Internet protocol (TCP / IP) (S1) communication. As a block for generating data in WiBro form by separating and converting data, the connection unit 10311, the decimal conversion unit 10313, the separation unit 10315, the complement conversion unit 10317, And a data generator 10319.

The connecting unit 10311 connects to the MIMO-OFDM block 101 via TCP / IP (S1) communication to receive digital received data A / D converted by the MIMO-OFDM block 101.

When the decimal conversion unit 10313 is connected to the MIMO-OFDM block 101 by the connection unit 10311, the received data provided by the connected MIMO-OFDM block 101 is an ASCII code value in the form of a character. In order to convert the data into hexadecimal values, the data is first converted into decimal form, and then converted into hexadecimal numbers and provided to the separating unit 10315.

The separation unit 10315 changes the hexadecimal number converted by the decimal conversion unit 10313 to a binary data type, and then determines which antenna is received by determining the antenna sign bit of the changed binary data. While referring to Table 1, it separates and provides it to the maintenance conversion part 10317.

31 30 24 23 12 11 0 Sign bit Null bit Imaginary Real

Here, Table 1 is a structure of data in the form of WiBro, which is represented by 32 bits in one form. More specifically, when the 31st bit is '0' (a signal received from the first antenna) and '1' (Signal received through the second antenna) means that the sign bit value (Sign Bit) is present, means that there is a null bit value in the 24 ~ 30th bit, It means that the complex bit value exists in the 12th to 23rd bits, and the real bit value exists in the 0th to 11th bits.

In the complementary converter 10317, the 23rd bit and the 11th bit shown in Table 1 represent the signs of the complex part and the real part, respectively, and when the sign bit is 0 in the complex part, the data value is a positive value. If the sign bit is 1 in the complex part, the data value is negative. That is, when the sign bit is 0 in the complex part, the data of the remaining 11th bit except the sign bit is provided to the data generating unit 10319 as it is, whereas when the sign bit is 1 in the complex part Two's complements are taken to the data of the 11th bit in the real part except for the sign bit, and provided to the data generating unit 10319.

The data generating unit 10319 provides the transmission verifying unit 1033 to verify the remaining 11-bit binary data values in the real part provided from the complementary converting unit 10317 and converts them into decimal numbers as shown in Table 1 below. Create data in WiBro format. In addition, the data generating unit 10319 is provided to the transmission verifying unit 1033 to verify the 11-bit binary data value taken by the two's complement provided from the complement conversion unit 10317, and is converted into a decimal number. Create WiBro data as shown below.

The transmission verification unit 1033 supports binary data loaded by the data loading unit 1031 through three modulation schemes of QPSK, 16QAM, and 64QAM, and supports the loaded binary data in three modulation schemes and those described in FIG. Modulation is applied to the gray code mapping rule, and then verified, and the verification result is provided to the output means 105.

The MIMO channel estimator 1035 may estimate the data channel loaded by the data loading unit 1031 through the up / down frame structure, which is downlink as shown in FIG. 4. It consists of a frame, an uplink frame, and a TTG and RTG section.

Here, the downlink frame and the uplink frame use a time division duplex (TDD) scheme divided by transmission time. In addition, the pilot frame and data subcarriers are mapped to the downlink frame in a cluster structure, and the pilot frame and data subcarriers are mapped to the tile structure in the uplink frame. The mapped pilot signal can be transmitted through an assigned subcarrier after being modulated by BPSK, and the power used for data transmission is 2.5 ㏈ higher than the power used for the subcarrier.

The downlink frame in the MIMO channel estimator 1035 can estimate a channel through downlink, and all data received through the downlink pass through the same channel regardless of whether or not a subcarrier is assigned to the corresponding user. As the extracted data, a channel is estimated and provided to the output means 105 using interpolation as shown in FIG. 5 while using pilot signals adjacent to subcarriers and symbol positions assigned to the user.

For example, FIG. 5 illustrates a channel estimation method in a downlink PUSC channel structure. When estimating a channel corresponding to a third symbol, a linear interpolation method is used as a left and right pilot subcarrier position channel estimation value of a corresponding subcarrier on a time axis. The channel of the corresponding subcarrier is estimated, and the channel is estimated using the linear interpolation method on the frequency axis using the channel estimate of the linear interpolated subcarrier and the pilot subcarrier.

The uplink frame in the MIMO channel estimator 1035 estimates a channel through the uplink, and the uplink is received because signals transmitted from each mobile communication terminal (not shown) are affected by different channels. Accordingly, when performing channel estimation on a signal transmitted from a specific mobile communication terminal, the signals received from the remaining mobile communication terminals cannot be used. That is, in the uplink channel estimation of the data subcarrier, unlike the downlink, the channel is estimated and provided to the output means 105 using the interpolation method as shown in FIG. 6 while using only the channel of the pilot subcarrier in the same tile.

For example, FIG. 6 illustrates a channel estimation method in an uplink PUSC channel structure. In order to estimate a channel corresponding to a second symbol, a linear interpolation method is used for a subcarrier located at a pilot subcarrier position on the left and right sides of a corresponding subcarrier on a time axis. After estimating the channel, the channel is estimated using the channel estimate of the linear interpolated subcarrier and the pilot subcarrier.

The reception verifying unit 1037 includes a symbol timing recovering unit 10371, a frequency offset estimating unit 10373, and a data quality analyzing unit 10375.

The symbol timing recovery unit 10371 is a block for restoring symbol timing of data loaded by the data loading unit 1031. The symbol timing recovery unit 10371 uses a double sliding window technique as shown in FIG. It restores and provides it to the output means 105.

That is, referring to FIG. 8, the baseband signal passes through sliding windows A and B, and A's total energy a _n and B's total energy b _n are represented by Equation 1

Can be applied to. Here, r _n means a received signal at the n point.

The total energy (a _n ) of A and the total energy (b _n ) of B are obtained from Equation 2

The timing recovery point is determined by finding the point of the largest value obtained by applying to.

The frequency offset estimator 10373 is a block estimated by using a cyclic prefix (CP) existing in an OFDM symbol. As shown in FIG. Represents the first data symbol.

That is, referring to FIG. 9, the same data is allocated to the first and second sections of the preamble. Here, when there is a frequency offset, A, which is a CP section, and B, which is an original data section of the CP, are the same except for the phase difference. The phase difference between the A portion and the B portion is calculated and the frequency offset is estimated and provided to the output means 105.

In other words, the phase difference between the A portion and the B portion is expressed by Equations 3 and 4

Is calculated through.

Here, T means 10 MHz as the sampling frequency.

In addition, the frequency offset Δf is expressed by Equation 5 using Equation 3 and Equation 4.

A block diagram for frequency offset estimation using CP is shown in FIG. 10.

The data quality analysis unit 10375 analyzes three qualities of an error vector magnitude (Error Vector Magnitude, EVM), an average spectral mask, and a constellation & signal to noise ratio (SNR). 105).

First, the EVM calculates the difference between the ideal signal vector and the signal vector affected by noise as shown in FIG.

Apply to get EVM.

Where xi and yi are coordinate values of an ideal signal vector, and xm and ym are coordinate values of a signal vector transformed by noise or other influences.

Second, the average spectral mask uses the pilot and data subcarriers within the selected burst, using samples with fast Fourier transforms (FFTs), and the pilot and data subcarriers assigned to each symbol around the subcarrier axis. Take the average of and output the result on the frequency axis.

Third, Constellation & SNR uses the pilot and data subcarriers in the selected burst and uses the resultant after taking the FFT. Equations 7, 8, and 9

,(여기서, SNR은 신호파워(SignalPower)를 잡음파워(NoisePower)로 나눈 값)

, Where SNR is the signal power divided by the noise power

The SNR can be obtained through.

Here, s ^ (n) denotes a reference signal and s (n) denotes a received signal.

The output means 105 outputs the verification result verified by the transmission verification unit 1033 for the operator to confirm, and also outputs the channel estimated by the MIMO channel estimator 1035 so that the operator can verify it. In addition, the operator outputs the symbol timing, the frequency offset estimation result, and the data quality analysis result restored by the reception verifying unit 1037.

Therefore, by verifying the quality of the transmitted / received data that has undergone A / D conversion by MIMO-OFDM, it is possible to analyze the signal quality of the MIMO-OFDM system, and also to verify the MIMO channel, and to be offline. It is possible to verify the performance of multi-systems (eg 4 * 4, 3 * 4) that are difficult to implement, and can be applied to various systems (smart antenna, MISO, ...) through software update.

In addition, since the present invention is disclosed as a right within the spirit and claims of the present invention, the present invention may include any modification, use and / or adaptation using general principles, and the present invention as a matter deviating from the description of the present specification. It includes everything that falls within the scope of known or customary practice in the art to which it belongs and falls within the scope of the appended claims.

As described above, the present invention enables the signal quality analysis of the MIMO-OFDM system and verifies the MIMO channel by verifying the quality of the transmission / reception data that has undergone A / D conversion by MIMO-OFDM. It is possible to verify the performance of multiple systems that are difficult to implement offline, and can be applied to various antenna systems through software updates.

Claims (21)

A system for verifying data converted by Multi-In Multi-Out (MIMO) -Orthogonal Frequency Division Modulation (OFDM), A data loading unit which connects to the MIMO OFDM and generates the WiBro data after separating and transforming the converted data; A transmission verification unit which modulates and verifies the data subjected to the loading process to modulation schemes of QPSK, 16QAM, and 64QAM and mapping rules of gray code, and outputs them through an output means; A MIMO channel estimator for estimating the loaded data channel for each uplink / downlink frame and outputting the same through an output means; Receiving verification unit for restoring the symbol timing of the loaded data, estimate the frequency offset, analyze the data quality and output through the output means System for verifying MIMO-OFDM comprising a. The method of claim 1, The reception verification unit, A symbol timing recovery unit for restoring symbol timing of the loaded data; A frequency offset estimator for estimating a frequency offset using a cyclic prefix (CP) existing in an OFDM symbol; And a data quality analyzer for analyzing the magnitude of an error vector of the loaded data (Error Vector Magnitude, EVM), an average spectral mask, and the quality of the constellation & signal to noise ratio (SNR). System for verifying MIMO-OFDM. The method of claim 2, The symbol timing recovery unit restores timing using a double sliding window technique. The method of claim 3, wherein The timing reconstruction includes the total energy a _{n of the} baseband signal in the sliding window A region and the total energy b _n of the base window signal in the sliding window B region. Equation

, Where r _n means the received signal at point n A system for verifying MIMO-OFDM, characterized in that the timing recovery point is determined as the point of the maximum value obtained by applying to. The method of claim 2, The frequency offset estimation may be performed by calculating a phase difference between A, which is the CP section, and B, which is an original data section of CP. Equation

(Where T stands for 10 MHz as the sampling frequency) The system for verifying MIMO-OFDM, characterized in that the calculation through the estimation. The method of claim 2, The EVM calculates a difference between a signal vector and a signal vector affected by noise. Equation

, Where xi and yi are the coordinates of the ideal signal vector, and xm and ym are the coordinates of the signal vector transformed by noise or other effects. The system for verifying MIMO-OFDM, characterized in that applied to calculate. The method of claim 2, The average spectral mask is a sample that takes a fast Fourier transform (FFT), and outputs a result obtained by taking the average of the pilot and data subcarriers assigned to each symbol around the subcarrier axis on the frequency axis. System for verifying MIMO-OFDM, characterized in that. The method of claim 2, The Constellation & SNR is a value obtained by dividing signal power by noise power. Equation

, Where s ^ (n) is the reference signal and s (n) is the received signal) System for verifying MIMO-OFDM characterized in that calculated through. The method of claim 1, The data loading unit, A connection unit for connecting to the MIMO-OFDM via TCP / IP communication to receive the converted data; A decimal conversion unit for converting the received data provided by the connected MIMO-OFDM into a decimal form and then converting the received data into a hexadecimal number; A separation unit for changing and converting the converted hexadecimal number into binary data and discriminating and separating an antenna sign bit of the changed binary data; A complementary conversion unit for performing two's complement on the data of the remaining bits in the real part except the sign bit when the separated sign bit has a negative value in the complex part; The separated sign bit converts the binary data value in the real part into a decimal number to generate WiBro data, and the separated sign bit converts the binary data value taken as a two's complement in the real part to a decimal number. Data generator to generate data of WiBro System for verifying MIMO-OFDM comprising a. The method of claim 1, The uplink / downlink frame, the system for verifying MIMO-OFDM, characterized in that using a time division duplex (Time Division Duplex). The method of claim 1, The downlink frame is a system for verifying MIMO-OFDM, characterized in that the pilot and data subcarriers are mapped in a cluster structure to estimate the channel. The method of claim 1, The uplink frame is a system for verifying MIMO-OFDM, characterized in that the pilot and data subcarriers are mapped to a tile structure to estimate the channel. The method of claim 1, And the uplink / downlink frame estimates a channel using interpolation. A method for verifying data converted by MIMO-OFDM, A first process of accessing the MIMO OFDM to generate the WiBro data after separating and transforming the converted data; A second process of modulating and verifying the data subjected to the loading process to a modulation scheme of QPSK, 16QAM, and 64QAM and a mapping rule of gray code, and outputting the same through an output means; A third process of estimating the loaded data channel for each up / down link frame and outputting the same through an output means; A fourth process of restoring symbol timing of the loaded data, estimating frequency offset, analyzing data quality and outputting the data through an output means Verification method for verifying MIMO-OFDM comprising a. The method of claim 14, The fourth process, Step 41 of restoring symbol timing of the loaded data; A step 43 of estimating a frequency offset using a CP present in an OFDM symbol; 45th step of analyzing the EVM, the average spectral mask, and the quality of the constellation & SNR of the loaded data Verification method for verifying MIMO-OFDM, characterized in that it further comprises. The method of claim 15, The symbol timing restoration in step 41 is a method for verifying MIMO-OFDM, wherein the timing is restored using a double sliding window technique. The method of claim 14, The first process, An eleventh step of accessing the MIMO-OFDM through TCP / IP communication to receive the converted data; A thirteenth step of converting the received data provided from the connected MIMO-OFDM into a decimal form and then converting the received data into a hexadecimal number; Changing the converted hexadecimal number to binary data, and then determining and separating an antenna sign bit of the changed binary data; When the separated code bit has a negative value in the complex part, a seventeenth step of taking a two's complement on the data of the remaining bits in the real part except the sign bit; The separated sign bit converts the binary data value in the real part into a decimal number to generate WiBro data, and the separated sign bit converts the binary data value taken as a two's complement in the real part to a decimal number. 19th step of generating data of WiBro Verification method for verifying MIMO-OFDM, characterized in that it further comprises. The method of claim 14, The uplink / downlink frame is a verification method for verifying MIMO-OFDM, characterized in that using a time division duplex (Time Division Duplex). The method of claim 14, The downlink frame is a verification method for verifying MIMO-OFDM, characterized in that the pilot and data subcarriers are mapped in a cluster structure to estimate the channel. The method of claim 14, The uplink frame is a verification method for verifying MIMO-OFDM, characterized in that the pilot and data subcarriers are mapped to a tile structure to estimate the channel. The method of claim 14, The uplink / downlink frame, the verification method for verifying MIMO-OFDM, characterized in that for estimating the channel using the interpolation method.

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