KR20060071559A - Method and device for optimally and sub-optimally demodulating constant-amplitude multi-code biorthogonal modulation signals using block orthogonal extended transorthogonal codes - Google Patents

Abstract

The invention 2 ^N of which relates to a block orthogonal expansion optimal and sub-optimal demodulation methods Amplitude Multi-codes binary orthogonal modulation signal using the transorthogonal code, the optimal demodulation method according to the invention corresponding to the combination of the N-bit information data, A correlation step of calculating a correlation value of a similar transorthogonal code and the modulated signal; Selecting a maximum value from 2 ^N correlation values calculated from the correlation step, and determining a maximum value of N bits of information data corresponding to the modulated signal from a similar transorthogoanl code corresponding to the maximum value.

Waveform coding, orthogonal code, Walsh code, Hadamard matrix, constant amplitude coding, transorthogonal code, block orthogonal extended transorthogonal code, optimal demodulation, suboptimal demodulation

Description

METHOD AND DEVICE FOR OPTIMALLY AND SUB-OPTIMALLY DEMODULATING CONSTANT-AMPLITUDE MULTI-CODE BIORTHOGONAL MODULATIONALSIGNALS USING BLOCK ORTHOG EXTENDED TRANSORTHOGONAL CODES}

1 is a conceptual diagram of a waveform encoding transmission method using an orthogonal code according to the related art.

2 is a diagram illustrating a relationship between input data and an output code in a waveform encoder using Walsh codes according to the related art.

3 is a diagram illustrating a relationship between input data and an output code in a waveform encoder using a transorthogonal code according to the related art.

4 is a structure diagram of a transmitter of prior art CS / CDMA.

5 is a structure diagram of a transmitter of a prior art CA-CS / CDMA.

FIG. 6 is a structure diagram of a transmitter of a conventional multi-code transosogonal code modulation scheme (MTOK). FIG.

7 is an illustration of a block orthogonal extended transosogonal code set.

8 is a structure diagram of a transmitter of a constant amplitude multiple coded binary orthogonal modulation scheme using a block orthogonal extended transorthogonal code according to a first embodiment of the present invention;

9 is a block diagram of an optimum demodulation device for a constant amplitude multiple coded binary orthogonal modulation signal using a block orthogonal extended transorthogonal code according to a second embodiment of the present invention.

Fig. 10 is a block diagram of a quasi-optimal demodulation device for a constant amplitude multiple code binary quadrature modulation signal using a block orthogonal extended transorthogonal code according to a third embodiment of the present invention.

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

81: information data bit stream 82, 91, 95: information data encoder

83: surplus bit string

84-a to 84-d, 92-a to 92-d, 96-a to 96-d: waveform encoder

85: code polarity converter 86, 93, 97: summer

87: summer output symbol 88: bandpass modulator

100: optimum demodulation device 110, 210: correlator bank

120, 220: maximum selection block 200: suboptimal demodulation device

230: Hard decision device 240: Inverter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiple code transmission system, and more particularly, to a method for optimal demodulation and quasi-optimal demodulation of a constant amplitude multiple coded binary orthogonal modulation signal using a block orthogonal extended transorthogonal code.

In general, considerations in selecting a modulation scheme for digital communication include bit error probability (BER), bandwidth, and required energy (E _b / N ₀ ). However, there is no absolute modulation scheme having all of these excellent performance indices, and the modulation scheme is determined through the compromise between the performance indices according to a given application environment. For example, in the case of M-ary modulation, one waveform of M = 2 ^k waveforms is generated corresponding to k input data bits. If we adopt MFSK (M-ary Frequency Shift Keying) or orthogonal signaling using orthogonal code, bit error rate performance improves as the input data bit (k) increases (required E _b / N ₀ Reduced), the signal bandwidth increases corresponding to k. Meanwhile, when nonorthogonal signaling (MSK) such as M-ary Phase Shift Keying (MPSK) or Quadrature Amplitude Modulation (QAM) is adopted, bandwidth efficiency is improved but bit error rate performance is reduced.

Thus, when available bandwidth is limited or the cost of frequency resources is high, modulation schemes such as MPSK or QAM are used, whereas frequency resources are not a problem but when MFSK or other orthogonality is required Modulation method can be adopted. On the other hand, when both frequency bandwidth efficiency and energy efficiency are important, such as personal wireless communication, an appropriate modulation method should be selected according to service requirements and system implementation environment.

As a conventional transmission technique, FIG. 1 illustrates the concept of a transmission scheme for digitally modulating using an orthogonal code as a waveform encoder.

Referring to FIG. 1, an orthogonal code composed of M = 2 ^k codes ( c ₀ ,…, c ₂ ^k ₋₁ ) corresponding to k bits of input data (b ₀ ,…, b _k-1 ) 11 One code c _i is selected from the set H _k 12, which is converted into a bipolar pulse signal by a pulse generator 13 and then carried on a carrier by a band pass modulator 14 do. For example, in a system in which Walsh codes are used as orthogonal codes, one row is selected by k bits of input data in a 2 ^k x 2 ^k Hadamard matrix and transmitted through a pulse generator.

2 illustrates an example of an orthogonal code according to a state of input data when the number of input data bits is 3 in the orthogonal code waveform encoding method of FIG. 1, and the input data set is {0,0,1}. C ₁ = {1, -1, 1, -1, 1, -1, 1, -1}.

However, in the above-described orthogonal code waveform encoding method of FIGS. 1 and 2, since the length of the codeword (codeword) is ^2k for each code, it can be transmitted using a frequency band of 1 Hz. When the maximum data rate is defined as bandwidth efficiency, the bandwidth efficiency becomes k / 2 ^k , and the efficiency decreases exponentially with increasing k.

Another example of a transmission scheme using waveform encoding is a transmission scheme using a transorthogonal code, which is created by deleting the first bit from an orthogonal codeword generated by a Hadamard matrix. The code is called a transorthogonal code or a simplex code [B. Sklar, Digital Communications Fundamentals and Applications , Prentice-Hall Inc., Englewood Cliffs, NJ, 1988].

3 shows an example of a transorthogonal code according to the state of input data, for example, when the number of input data bits is three. In transorthogonal modulation, a 2 ^k- 1 bit length codeword generated by k-bit information data is carried on a carrier and transmitted. The crosscorrelation coefficient of the transorthogonal code is shown in Equation 1.

When using transorthogonal codes, the energy efficiency is slightly increased compared to orthogonal modulation (ie, the energy required to obtain a given bit error rate is reduced), and a slight increase in bandwidth efficiency can be obtained. However, as k increases, the length of the code increases exponentially, and the improvement of bandwidth efficiency and energy efficiency is very small, which is similar to orthogonal modulation.

As described above, the transmission method of digital modulation using waveform encoding has a disadvantage of excellent bit error rate performance but very low bandwidth efficiency. Accordingly, in order to improve very low bandwidth efficiency in digital modulation using a waveform encoder, a code select CDMA (CS / CDMA; Code Select CDMA) using Walsh code as an orthogonal code and constructing and transmitting a multiple waveform encoder is used. CS / CDMA "method is proposed, and is disclosed in Korean Patent Application No. 2001-61738 (filed date: 2001.10.8).

4 illustrates a structure of a transmitter in the above-described CS / CDMA scheme, and each of the L waveform encoders 42 has a different Walsh code set. As shown, each of L blocks in the transmitter to which r + 1 bits of input data is input is one of 2 ^r Walsh codes included in each waveform encoder 42 by r bits of data [c _1]. (n), c ₂ (n),... , c _L (n)] is outputted, and the polarity of each code is determined by the remaining one bit and then input to the digital summer 43. The digital summer 43 sums the output codes of the L blocks described above, and then the bandpass modulator 45 carries the output symbols 44 output from the digital summer 43 on a carrier and transmits them.

The advantage of CS / CDMA described above is that bandwidth efficiency is increased by adopting a multi-code transmission structure while using waveform coding by orthogonal codes. However, when summing multiple codes, the magnitude of the output signal is not constant according to the summing result, which greatly affects the nonlinearity of the power amplifier.

In order to compensate for the shortcomings of CS / CDMA, a constant amplitude CS / CDMA (CA-CS / CDMA; Constant Amplitude coded CS / CDMA, hereinafter “CA-CS / CDMA”) method has been proposed. As disclosed in Korean Patent No. 2002-20158, the output data of the digital summer can be given a constant size by appropriately encoding the information data and generating excess data and inputting the same to the waveform encoder.

FIG. 5 illustrates a CA-CS / CDMA transmitter structure described above, and a description of the same or similar configuration as that of the CS / CDMA transmitter of FIG. 4 will be omitted.

As shown in Fig. 5, the CA-CS / CDMA transmitter has four waveform encoders 53, and the upper three waveform encoders 53 are inputted with r bits of information data, respectively. In the other waveform encoder 53, data encoded by Equation 2 is input by the encoder 52 to the information data input to the transmitter.

The amplitude of the output signal d encoded according to equation (2 ) is constant.

As another method for improving very low bandwidth efficiency in digital modulation using waveform encoders, a multi-code transorthogonal code modulation scheme (MTOK) has been patented by the applicant. (Korean Patent Application No. 2004-71620), which uses a new block orthogonal transorthogonal code instead of the existing transorthogonal code, and uses multiple block orthogonal transorthogonal coders in parallel instead of one coder to use multiple codewords. Add up.

The code used in MTOK is a 4x3 transorthogonal code that is sequentially expanded in block units. The code correlation between codes of the same block is maintained at -1/3 regardless of the block size. Has a property of being zero (that is, an orthogonal property). This transmission scheme is considerably more bandwidth efficient than the single block orthogonal or transortogonal modulation scheme, and the bit error rate performance is not significantly degraded.

FIG. 6 illustrates the structure of the MTOK transmitter described above, and divides the block orthogonal extended transorthogonal code set into L subset code groups to configure the waveform encoder 62 for each code group in parallel. The number of bits of the data 61 input to the waveform encoder 62 of each block is r , and since there are 2 ^r codes in each code group, the size of the entire code set is L · 2 ^r . The number of data bits simultaneously input to the transmitter is k = L.r, and each waveform encoder 62 outputs one codeword corresponding to r input bits, and then the L codewords output from each waveform encoder are summed up. The signal [d (n)] 64 summed at 63 is carried on the carrier by the band pass modulator 65 and transmitted.

In relation to the generation of the codes to be used in MTOK, 2 ⁿ x 2 ⁿ - 1 transorthogonal code matrix and an (i. E., The length of the cord 2 ^k 1 is the number of codes 2 ^k code set) to a basic matrix, Mathematical By continuously extending the code set in block units as shown in Equation 3, the number of possible codes can be doubled.

For example, FIG. 7 illustrates a 16x12 code matrix T ₄ having a 4x3 sized transorthogonal matrix (ie, k = 2) as a base matrix and performing the code expansion process of Equation 3 twice. When the block orthogonal extended transorthogonal code matrix generated as described above is divided into four quarters by row, codewords of different blocks (or different submatrices) are orthogonal to each other. Therefore, even if a plurality of (multiple) codes are added and transmitted, each code can be distinguished by performing correlation at the receiver.

As shown in FIG. 6, if a multi-code transmitter having four blocks is configured and each block uses a codeword in each group of block orthogonal extended transorthogonal codes described above, the output codewords of each block are orthogonal to each other. It can be seen that. Therefore, even if the output codewords of each block are added and transmitted, if the receiver implements a correlator for each block, the transmitted codeword can be found and the information bits corresponding to each codeword can be recovered.

As such, the MTOK method can improve the low bandwidth efficiency in the modulation using the waveform encoder, which is due to the block extension of the transorthogonal code and the structure of the multiple code.

However, in the conventional MTOK modulation scheme, adding a plurality of codes causes a problem that the size of the output symbol is not constant, requiring high linearity of the transmitter power amplifier.

 In order to solve the above-mentioned problems, the present invention provides a constant amplitude characteristic to a multi-code transmission scheme (MTOK) using a waveform encoder with block orthogonal extended transorthogonal codes, thereby reducing the effects of nonlinearity of the amplifier. Doing.

In addition, a second object of the present invention is to provide a demodulation device capable of optimally or suboptimally demodulating a constant amplitude multiple coded binary orthogonal modulation signal provided according to the above-described first object.

According to a first aspect of the present invention, there is provided a method for optimal demodulation of a full-width multiple coded binary orthogonal modulated signal using a block orthogonal extended transorthogonal code, comprising 2 ^N similar transorthogonal codes corresponding to a combination of N bits of information data. A correlation step of calculating a correlation value of the modulated signal; Selecting a maximum value from 2 ^N correlation values calculated from the correlation step, and determining a maximum value of N bits of information data corresponding to the modulated signal from a similar transorthogoanl code corresponding to the maximum value.

At this time, the maximum value selection step may determine the entire N bits of the information data from the binary index of the similar trasorthogonal code corresponding to the maximum value.

According to a second aspect of the present invention, there is provided a method of suboptimal demodulation of a full-width multiple coded binary orthogonal modulated signal using a block orthogonal extended transorthogonal code, wherein among 2 ^N similar transorthogoanl codes corresponding to a combination of N bit information data, A correlation step of selecting 2 ^N-1 pseudotransorthogonal codes reflecting binary orthogonal characteristics and calculating a correlation between the selected pseudotransorthogonal codes and the modulated signal; Selecting a maximum value from 2 ^N-1 correlation values calculated from the correlation step and determining a maximum value of N bits of information data corresponding to the modulated signal from a similar transorthogoanl code corresponding to the maximum value; And an inverting step of inverting the bits for determining the phase of the modulated signal among the determined N bits of information data to match the phase of the maximum value selected from the maximum value selecting step.

According to still another aspect of the present invention, there is provided a demodulation device comprising an apparatus for performing each of the steps of the first and second aspects of the invention described above.

On the other hand, in the present invention, the constant amplitude multi-signal binary orthogonal modulation apparatus using block orthogonal extension transorthogonal code has four waveform encoders in parallel, adds codes output from each waveform encoder, and loads them on a carrier to transmit. It is composed. The information bit stream input to the transmitter is subjected to the constant amplitude encoding process and then input to the waveform encoder. In constant amplitude coding, a code with a code rate of 3/4 is generated, and extra bits are generated in addition to the input data. The output data of the constant amplitude encoder is input to four waveform encoders so that one code is selected from the code set of each waveform encoder and output. When the code of the waveform encoder is selected and output as a surplus bit generated by the constant amplitude encoding, the amplitude becomes constant when added to the remaining three waveform encoder output codes.

The block orthogonal extension transorthogonal code set used in the present invention is generated by sequentially extending the basic transorthogonal code set in units of blocks. Make sure that your code is orthogonal to each other. Here the default transorthogonal code set is the code set created by deleting the first column of the Hadamard matrix. The size of the block orthogonal extension transorthogonal code set is (4x2 ^r ) x (3x2 ^r ), where r = 2, 3,... Becomes. That is, a set of 4x2 ^r codes having a length of 3x2 ^r is generated. In the present invention, the entire code set is divided into several subsets to be used in each waveform encoder. According to the code extension method and the code set division method used in the present invention, codes output from each encoder are orthogonal to each other, so that even if multiple codes are added and transmitted in a code adder, they do not interfere with each other. On the other hand, when multiple codes are added, the size of the output symbol is generally not constant. However, when the encoding of the information data proposed in the present invention is used, the amplitude of the output symbol of the multiple code summer is constant.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 8 illustrates the structure of a transmitter according to a first embodiment of the present invention, and shows four waveform encoders 84-a, 84-b, 84-c, and 84-d using block orthogonal extended transorthogonal codes. One of the waveform encoders 84-d operates as a redundant encoder. The upper three waveform encoders 84-a, 84-b, and 84-c are respectively input with r bit input information bit strings, and the redundant encoder 84-d receives the aforementioned information bit strings with the information data encoder 84. The redundant bit streams b _3,0 ,..., B _{3, r-1} ) 83 generated by encoding the same as in FIG. ₃ are input, thereby output codes c ₀ , c ₁ , c ₂ , c ₃ are added in summer 86 so that the size of the output symbol is constant.

Referring to the operation of the transmitter illustrated in FIG. 8 in more detail, the information data 81 inputted through a serial-to-parallel converter (not shown) includes the top three waveform encoders 84-a, 84-b, and 84-c. R bits are inputted. The information bit encoder 82 generates an excess bit string 83 from the information data 81 and inputs it to the excess waveform encoder 84-d.

Each waveform encoder block 84-a, 84-b, 84-c, 84-d has a r input channel and is a subset of codes consisting of 2 ^r codes corresponding to r bits of input data. Select one code from) and print it. The code used in the waveform encoder is a block orthogonal extension transorthogonal code. Each waveform encoder encodes a matrix (code set) of (4x2 ^r ) x (3x2 ^r ) size into a subset formed by dividing the matrix into four rows. Codes output from each waveform encoder are input to a summer 86. The code output from the redundant waveform encoder block 84-d is inputted to the summer after inverting 1 and -1 in the code polarity converter 85, and the effects of the code polarity converter 85 are described in Equations 6 to below. It explains in connection with 8. The multiple code summer 86 adds four codes input from each waveform encoder block to generate an output signal 87. The summer output signal is transmitted 88 on the carrier.

Meanwhile, the information data encoding method and transmitter structure according to the first embodiment of the present invention can be described in comparison with a conventional CA-CS / CDMA transmission scheme. First, the block orthogonal extension transorthogonal code used in the present invention can be described. Let's take a look at the relationship with the Hadamard matrix used in CA-CS / CDMA.

As described above, a transorthogonal code matrix is created by removing the first column from the Hadamard matrix (see example in FIG. 3). To represent d in size 2 ^k x2 ^k of the Hadamard matrix H _k, H _k Hadamard matrix can be generated as shown in Equation (4).

When a transorthogonal code matrix of size 2 ^k x2 ^k -1 is formed by removing the first column from the Hadamard matrix, T _k , for example, when k = 2, the transorthogonal code matrix T ₂ of size 4x3 is represented by Equation 5 Becomes

Block Orthogonal Extension The transorthogonal code matrix is created by extending the basic transorthogonal code matrix according to the procedure given in Equation 3. Extends along the primary transorthogonal code matrix T ₂ in equation (3) made of a matrix T ₃ is equal to that size there is a 8x6, the matrix T ₃ is removed, the first column and the fifth column from the Hadamard matrix of size 8x8 H ₃ . Matrix T ₃ again extended orthogonal block that is created by applying the equation (3) to transorthogonal code matrix, T ₄ is the size of 16x12, the matrix is the first, fifth, ninth, thirteenth in the size 16x16 Hadamard matrix H ₄ Equivalent to removing heat. All rows of the Hadamard matrix, or all code, are orthogonal to each other. On the other hand, the rows of the basic transorthogonal code matrix are not orthogonal to each other and have a correlation coefficient of -1/3. However, if the matrix T ₄ generated by applying Equation 3 twice is divided into four rows (see FIG. 7), two codes belonging to different submatrices are orthogonal to each other. Therefore, if the waveform encoder is configured for each orthogonal block, the codes output from the four waveform encoders are orthogonal to each other.

The block orthogonal extension transorthogonal code matrix T ₅ , which is made three times using Equation 3 for the basic transorthogonal code matrix, is divided into eighths by row, and the correlation between the codes in the same block is -1/3. The correlation between the codes in the other blocks is zero. However, in the case of dividing the matrix T ₅ into four rows by row, the correlation coefficient between codes in the same block becomes -1/3 or 0, and the correlation coefficient between codes in different blocks becomes zero. The association between these two matrices can continue to be applied to larger matrices. That is, if a block orthogonal extension transorthogonal code matrix formed by extending the basic transorthogonal code matrix two or more times by using Equation 3 is divided into four blocks in units of rows, the correlation coefficient between different codes in the same block is -1 /. 3 or 0, and the correlation coefficient between codes of different blocks is 0.

Next, the relationship between the transmitter structure and the CA-CS / CDMA transmitter structure according to the first embodiment of the present invention will be described.

In CA-CS / CDMA, the Hadamard matrix is divided into quarters and used as the code of the waveform encoder. That is, as described above, when the number of input bits per block is r + 1, one of 2 ^r orthogonal codes is selected from r bits of data in each waveform encoder, and the polarity of the selected code is determined by the remaining bits. (Ie multiply the selected code by the remaining bits). Subsequently, the codes output from the four blocks are added by the adder and then loaded on a carrier and transmitted.

At this time, the size of the Hadamard matrix used in CA-CS / CDMA is 2 ^{r + 2} x2 ^{r + 2} , and the data input to the four blocks is {b ₀₀ , b _01,. , b _0r }, {b ₁₀ , b ₁₁ ,... , b _1r }, {b ₂₀ , b ₂₁ ,... , b _2r }, {b ₃₀ , b ₃₁ ,... , b _3r }, the first three bit strings are information data, and the last bit string {b ₃₀ , b ₃₁ ,... , b _3r } is a redundant bit string generated by encoding the information data. When the codes output from the waveform encoders are c ₀ , c ₁ , c ₂ , and c ₃ (code c _j is a code having a length of 2 ^{r + 2} ), the transmission signal d output from the summer is represented by mathematics. It is expressed as Equation 6.

In general, the output signal d is not constant in size, but when the excess bit string generated by the CA-CS / CDMA coding method is used, the magnitude of the output signal is constant. The redundant bit string generation method for making the amplitude of the output signal constant is shown in Equation (7).

In the transmitter according to the first embodiment of the present invention, since information data does not change the polarity of the waveform encoder output code, it can be regarded as b _0r = b _1r = b _2r = 1. On the other hand, the block orthogonal extended transorthogonal code matrix has the first column, the fifth column, the ninth column, the thirteenth column,... In the Hadamard matrix having the same row size. And the like, so that b _0r = b _1r = b _2r = 1 in the CA-CS / CDMA transmitter, and the first, fifth, ninth, and ninth in the output signal after applying Equations 6 and 7 13,... By removing the element of, the same result as the output signal of the transmitter according to the first embodiment of the present invention can be obtained.

The above result is applied to the transmitter according to the first embodiment of the present invention as follows. The number of data bits input to each waveform encoder is r, and the equation 7 is encoded. In this case, unlike CA-CS / CDMA, b _0r , b _1r , b _2r , and b _3r do not exist. Therefore, for constant amplitude encoding, b _0r = b _1r = b _2r = 1 in the second equation of Equation 7 and b _3r = 0 as the result of the exclusive OR of odd bits (b _0r , b _1r , b _2r ). And apply it to the equation (6).

This process is summarized as follows. In a multi-code transmission system using block orthogonal extended transorthogonal codes as waveform encoding, data input to the redundant waveform encoder is generated as shown in Equation 8 and the output codes of the respective waveform encoders are summed to generate a signal having the same amplitude.

According to Equation (8), the information data encoder 82 inputs each i-th input channel (i = 1,... Of the waveform encoders 84-a, 84-b, 84-c into which r bits of information data are input, respectively. The bits input to .r are exclusive-ORed to generate the i th bit of the redundant bit string, and are input to the i th input channel of the waveform encoder 84-c. The waveform encoder 84-c selects one code c ₃ corresponding to the redundant bit string of the r bits, and the code polarity converter 85 outputs the code c output from the waveform encoder 84-c. The polarity of ₃ ) is inverted and output to the summer 86. Summer 86 is then polarized by code c ₀ , c ₁ , c ₂ selected from waveform encoders 84-a, 84-b, 84-c and code polarity converter 85, respectively. By summing the inverted codes (-c ₃ ), the output symbols of summer 86 can maintain a constant amplitude characteristic.

As described above, when the transmitter structure and the encoding method according to the first embodiment of the present invention are used, the size of the output symbol is constant while using the MTOK's multicode structure, and thus, a simple bandpass modulation method such as BPSK is used. Signal can be transmitted.

FIG. 9 illustrates an optimal demodulation device according to a preferred embodiment of the present invention.For convenience of description, when the total information data is 9 bits in the transmitter of FIG. 8 and the number of input bits per block is 3 (that is, r) = 2) is illustrated.

As shown, the optimal demodulation device 100 is based on a maximum likelihood (ML) algorithm, and the 512 pseudo transorthogonal codes (s ₀ to s ₅₁₁ ) (9 bit information) with the above-described received signal. 512 (= 2 ⁹ ) correlators 110 for separately outputting a correlation value of a positive amplitude binary orthogonal code output from a transmitter corresponding to each bit combination of data, and 512 outputs from the correlator 110. And a maximum value selection block 120 for determining a similar transorthogonal code corresponding to the maximum value among the correlation values and outputting information data corresponding to the determined similar transorthogonal code bit by bit.

,

,

,

,

,

,

,

,

)은 당해 유사 transorthogonal 코드에 대응하는 정보 데이터 비트에 대응하도록 설정되며, 이에 따라 최적 복조 장치(100)는 수신 신호와의 상관값이 최대가 되는 유사 transorthogonal 코드의 인덱스를 찾아 9 비트의 정보 데이터를 동시에 일괄적으로 복조할 수 있다. In this case, a binary representation of the indices of the aforementioned 512 pseudo-transorthogonal codes (

,

,

,

,

,

,

,

,

) Is set to correspond to the information data bits corresponding to the pseudo-transorthogonal code, and accordingly, the optimal demodulation device 100 finds the index of the pseudo-transorthogonal code having the maximum correlation value with the received signal and finds 9-bit information data. Demodulation can be done in batches at the same time.

FIG. 10 illustrates a configuration of a sub-optimal demodulation device 300 according to a preferred embodiment of the present invention. Similar to FIG. 9, the total information data in the transmitter of FIG. 8 is 9 bits and for each block. The case where the number of input bits is 3 (that is, r = 2) is illustrated.

,

,

)(변조 신호에 이진직교 특성과 관련됨)의 반전 여부를 결정하는 경판정기(230)와, 상기 경판정기(230)로부터의 출력 신호에 따라 데이터 비트(

,

,

)의 위상을 반전하기 위한 반전기(240)로 구성되어 있다. Referring to FIG. 10, the suboptimal demodulation device 200 includes 256 correlators 210 separately outputting correlation values of a received signal and 256 similar transorthogonal codes, and a correlation value output from the 256 correlators 210. A maximum value selection block 220 for determining a similar transorthogonal code corresponding to the maximum value and outputting information data bits corresponding to the determined similar transorthogonal code, and the maximum value output from the maximum value selection block 220. Depending on the phase, the data bits (

,

,

(Determining whether the modulation signal is related to the binary orthogonal characteristic) or not, and the data bit (depending on the output signal from the hard determiner 230).

,

,

And an inverter 240 for inverting the phase.

,

,

)의 홀수 인덱스 부호와 짝수 인덱스 부호 사이에는 180도의 위상차가 존재한다. 따라서, 준최적 복조장치(200)는 홀수 인덱스 또는 짝수 인덱스를 갖는 256개의 유사 transorthogonal 코드(s₀ 내지 s₂₅₅)를 선별하여 수신 신호와의 상관값을 비교하고, 상관값이 최대가 되는 유사 transorthogonal 코드에 대응하는 9 비트의 정보 데이터를 일단 판정하며, 최대 상관값의 부호와 일치하도록 데이터 비트(

,

,

)의 위상을 선택적으로 반전함으로써 송신된 정보 데이터를 최종적으로 판정한다.According to the present invention, since the 512 similar transorthogonal codes corresponding to each combination of 9 bits of information data have binary orthogonal characteristics, the data bits for providing such binary orthogonal characteristics (

,

,

There is a 180 degree phase difference between the odd index code and the even index code. Accordingly, the sub-optimal demodulation device 200 selects 256 similar transorthogonal codes (s ₀ to s ₂₅₅ ) having odd or even indices, compares the correlation with the received signal, and produces a similar transorthogonal with the maximum correlation value. The nine bits of information data corresponding to the code are determined once, and the data bits (

,

,

By selectively inverting the phase of), the transmitted information data is finally determined.

Although the preferred embodiment according to the present invention has been described above, this is merely exemplary and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the protection scope of the present invention should be defined by the following claims.

As described above, according to the present invention, in the multiple code transmission scheme (MTOK) using a waveform coder with block orthogonal extended transorthogonal codes, as the output signal generated by adding multiple codes has a constant amplitude, digital modulation using a waveform encoder is performed. The bandwidth efficiency is significantly improved compared to orthogonal modulation of a single code while maintaining robustness to the noise. In addition, the output signal has a constant size, which is less affected by the nonlinearity of the amplifier, thereby increasing power efficiency and implementing a low-cost transmitter.

That is, if the bandwidth efficiency is defined as the minimum bandwidth required to transmit one bit of data, the transmission scheme proposed in the present invention has the advantage that the bandwidth efficiency is higher than that of the modulation scheme using the Walsh code-based waveform encoder. In the transmission scheme proposed in the present invention, for example, the entire code set is divided into four subsets and assigned to four waveform encoders. Information data is input to the three waveform encoders, and generated by constant amplitude encoding on the other waveform encoder. The surplus bit string is input. At this time, if the transmitter is configured to input r bits of data per waveform encoder, the bandwidth efficiency is 3r / (3x2 ^r ) since a total of 3r bits of information data are encoded and transmitted as an output code of a 3x2 ^r chip. If the information inputted at the same data rate is transmitted by orthogonal code encoding, the bandwidth efficiency is 3r / 2 ^3r and the bandwidth efficiency is relatively low since 3r bits of input data are encoded and transmitted to the output code of the 2 ^3r chip. . As described above, using the transmission scheme proposed in the present invention can greatly improve the bandwidth efficiency compared to the scheme using a single orthogonal code encoder, and the amplitude of the output symbol is constant, thereby being less affected by the nonlinearity of the amplifier.

In addition, according to the present invention, an optimal demodulation method of a constant amplitude multi-signal binary orthogonal modulation signal has a performance improvement of about 3 dB compared to a conventional constant amplitude multi-signal orthogonal demodulation device at a BER of 10 ⁻⁵ . In addition, the sub-optimal demodulation method according to the present invention can halve the number of pseudo orthogonal codes required for optimal demodulation by using the binary orthogonality characteristic of the modulated signal, and thus obtain a demodulation performance equivalent to the above-described optimal demodulation. The advantage is that hardware can be implemented at a lower cost.

Claims (8)

A method for optimally demodulating a constant amplitude multiple coded binary orthogonal modulation signal in a full amplitude multiple coded binary orthogonal modulation system that waveform-encodes N bits of information data using a block orthogonal extension transorthogonal code, A correlation step of calculating a correlation value between 2 ^N similar transorthogonal codes corresponding to the combination of the N bits of information data and the modulated signal, A maximum value selection step of selecting a maximum value from 2 ^N correlation values calculated from the correlation step and determining N bits of information data corresponding to the modulated signal from a similar transorthogoanl code corresponding to the maximum value Optimal demodulation method for a double amplitude binary coded quadrature modulated signal using block orthogonal extended transorthogonal code. 2. The method of claim 1, wherein the selecting of the maximum value comprises determining the entire N bits of the information data from a binary index of a pseudo trasorthogonal code corresponding to the maximum value. Optimal Demodulation Method of Modulated Signal. An apparatus for optimally demodulating a constant amplitude multiple code binary orthogonal modulation signal in a constant amplitude multiple coded binary orthogonal modulation system that waveform-encodes N bits of information data using a block orthogonal extension transorthogonal code, A correlation unit for calculating a correlation value between 2 ^N similar transorthogonal codes corresponding to the combination of the N bits of information data and the modulated signal, A maximum value selector which selects a maximum value from 2 ^N correlation values calculated from the correlation part and determines N bits of information data corresponding to the modulated signal from a similar transorthogoanl code corresponding to the maximum value Optimal demodulation device for constant amplitude multi-signal binary orthogonal modulation using block orthogonal extension transorthogonal code. The binary amplitude multiple coded binary orthogonal modulation using the block orthogonal extension transorthogonal code according to claim 3, wherein the maximum value selector determines the entire N bits of the information data from the binary index of the pseudo trasorthogonal code corresponding to the maximum value. Optimal demodulation device of the signal. A method of semi-optimal demodulation of a constant amplitude multiple coded binary orthogonal modulation signal in a full amplitude multiple coded binary orthogonal modulation system that waveform-encodes N bits of information data using a block orthogonal extended transorthogonal code, Selecting 2 ^N-1 pseudo transorthogonal codes by reflecting binary orthogonality among 2 ^N pseudotransorthogoanl codes corresponding to the combination of the N bit information data, and calculating a correlation between the selected pseudo transorthogonal codes and the modulation signal Correlation step, Selecting a maximum value from 2 ^N-1 correlation values calculated from the correlation step, and determining a maximum value of N bits of information data corresponding to the modulation signal from a similar transorthogoanl code corresponding to the maximum value; An inverting step of inverting the bits for determining the phase of the modulated signal among the determined N bits of information data so as to match the phase of the maximum value selected from the maximum value selecting step A suboptimal demodulation method for a constant amplitude multiple coded binary orthogonal modulated signal using a block orthogonal extended transorthogonal code. 4. The method of claim 3, wherein selecting the maximum value simultaneously determines the entire N bits of the information data from an index of a pseudo orthogonal code corresponding to the maximum value. Suboptimal demodulation method of modulated signal. An apparatus for semi-optimal demodulation of a constant amplitude multiple coded binary orthogonal modulation signal in a constant amplitude multiple coded binary orthogonal modulation system that waveform-encodes N bits of information data using a block orthogonal extended transorthogonal code, Selecting 2 ^N-1 pseudo transorthogonal codes by reflecting binary orthogonality among 2 ^N pseudotransorthogoanl codes corresponding to the combination of the N bit information data, and calculating a correlation between the selected pseudo transorthogonal codes and the modulation signal Correlator, A maximum value selector which selects a maximum value from 2 ^N-1 correlation values calculated from the correlation part and determines N bits of information data corresponding to the modulated signal from a similar transorthogoanl code corresponding to the maximum value; An inverting unit for inverting a bit for determining the phase of the modulated signal among the determined N bits of information data so as to match the phase of the maximum value selected from the maximum value selecting unit Suboptimal demodulation device for a constant amplitude multiple coded binary orthogonal modulated signal using a block orthogonal extended transorthogonal code comprising a. 8. The method of claim 7, wherein the maximum selector simultaneously determines the entire N bits of the information data from an index of a pseudo orthogonal code corresponding to the maximum value. Suboptimal demodulation device for signals.

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