CN101621490B - Method for modulation diversity joint codes of OFDM system - Google Patents

Abstract

A method for joint coded modulation diversity for OFDM systems, the method introduces signal modulation diversity through rotation and component interleaving of modulation constellation diagrams, and diffuses and distributes data to be transmitted to different components by rotating modulation and component interleaving, Make the data of different components fade independently on the channel to increase the advantage of signal space diversity; then select the optimal rotation angle to obtain the maximum improvement of transmission performance; at the same time, introduce OFDM frequency diversity and time-frequency interleaving diversity, so that it can be more effectively Improve system performance. The present invention is an improvement of the applicant's previous invention patent application "A Method for Signal Diversity of OFDM System" (application number: 2008102264831). The enhancement and improvement of the transmission performance obtained by the diversity technology obtained through two-dimensional rotational modulation is extended to multi-dimensional rotational modulation, so that modulation diversity can be better utilized, and then combined with time diversity and frequency domain diversity to improve system performance.

Description

A Method for Joint Coding and Modulation Diversity in OFDM System

technical field

The present invention relates to a method for joint coding and modulation diversity in OFDM system, to be precise, relates to a method for comprehensively adopting multi-dimensional rotation modulation, channel coding and diversity to signal in OFDM system, so as to make good comprehensive utilization Time diversity, frequency diversity, modulation diversity and channel coding gain under fading channel to reduce the frame error rate of the system belong to the technical field of diversity in data communication.

Background technique

Since Ungerboeck proposed Trellis Code Modulation (TCM) technology in 1982, Coded Modulation CM (Coded Modulation) technology has always been a hot research topic in the field of communication. The basic idea of TCM is to comprehensively consider and design the encoder and modulator as a whole, so that the encoded signal sequence generated by the cascaded encoder and modulator has the largest Euclidean distance. The current theory and practice have shown that TCM can achieve the best performance in the additive white Gaussian channel (AWGN Channel). However, when TCM is used in mobile fading channels, it is found that its performance becomes very poor. Therefore, how to find the best coding and modulation scheme in a fading channel has become a research hotspot in recent years.

The advantage of the TCM coding method is to maximize the Euclidean distance of the coded signal sequence, which can play a good role in the AWGN channel. But for the fading channel, the improvement of the performance depends on increasing the number of diversity and increasing the product distance, which makes the TCM coding method have no performance advantage in the fading channel transmission.

In 1992, Zehavi first proposed the Bit Interleave Code Modulation algorithm BICM (Bit Interleave Code Modulation). Compared with the traditional TCM, the performance of this algorithm under the Rayleigh channel has been significantly improved. In 1996, Nina, G Caire and others calculated the capacity of the BICM scheme in the case of ideal interleaving, and proved that the capacity of most signal sets with Gray mapping is almost equal to the capacity of the signal set itself. In this way, it is theoretically explained that BICM can obtain the same coding gain as TCM, not just a sub-optimal coding scheme as originally thought.

In the BICM algorithm, the bit interleaving technique plays a decisive role in increasing the time diversity of coded modulation, however, in Gaussian channel, its performance deteriorates due to the decrease of the minimum Euclidean distance.

Orthogonal Frequency Division Multiplexing OFDM (Orthogonal Frequency Division Multiplexing) is a broadband multi-carrier technology. It converts the high-speed transmission data stream into a set of low-speed parallel transmission data streams, which greatly reduces the sensitivity of the system to the frequency selectivity of multipath fading channels, and thus has good anti-noise and anti-multipath interference capabilities. , suitable for high-speed data transmission in frequency-selective fading channels. Therefore, people naturally think that if OFDM and BICM can be combined, the communication quality will be further improved.

As we all know, in fading channels, the role of "diversity" is very important. In the optimal diversity case, the error probability decreases exponentially as the average SNR increases. In the BICM algorithm, although the bit interleaving technology increases the time diversity of coded modulation; however, the transmission performance of this technical scheme in Gaussian channel becomes worse due to the decrease of the minimum Euclidean distance. Therefore, how to solve this technical problem has become a focus of attention of technical personnel in the industry.

Contents of the invention

In view of this, the object of the present invention is to provide a method for joint coding modulation diversity of OFDM system, the method introduces signal modulation diversity by changing the rotation angle and component interleaving of modulation constellation diagram, by rotating modulation and component interleaving, Diffusion and distribution of the data to be transmitted to different components, so that the data of different components fade independently on the channel, increasing the advantage of signal space diversity; then select the optimal rotation angle to obtain the maximum improvement in transmission performance; at the same time, introduce OFDM frequency Diversity and time-frequency interleaving diversity, which can improve system performance more effectively.

In order to achieve the above object, the present invention provides a method for joint coded modulation diversity of OFDM system, characterized in that, the method comprises the following steps:

(1) The sending end initializes the sending data: encode and modulate each user’s sending data according to the set encoding and modulation methods, and then perform modulation on the symbol vector blocks of all users according to the set rotation angle The I-way in-phase component and the Q-way quadrature component of the multi-dimensional rotation modulation are carried out, and then the symbol vector block after the rotation modulation is stored;

(2) The sender allocates OFDM time-frequency resources to the symbol vector blocks of all users in the memory according to the set OFDM mode, distributes the symbol vector blocks of each user to each OFDM symbol in sequence, and then assigns the OFDM symbol vector blocks to each OFDM symbol The symbol vector block of each user of the Q-path interleaving process is carried out;

(3) According to the preset OFDM modulation length and the inverse fast Fourier transform IFFT operation length, the sending end pads the bit length of each OFDM symbol that is less than the IFFT operation length with zeros, and then fills each OFDM symbol with zeros Perform OFDM processing including IFFT operation and adding cyclic prefix CP, and then send data;

(4) After the receiving end receives the data, first perform OFDM processing on the data block symbol by removing CP and fast Fourier transform FFT operation, then perform phase compensation and zero removal, and then perform Q-path solution on the obtained OFDM symbols in turn Interleaving, OFDM solution time-frequency resource allocation, rotation demodulation and decoding, to obtain the required data information.

The present invention is a method for joint coding and modulation diversity in OFDM systems, which is an extension and improvement of the applicant's patent application "A Method for Signal Diversity in OFDM Systems" (application number: 2008102264831) last year. The invention patent application in 2008 is to obtain the improvement and improvement of transmission performance by diversity technology through two-dimensional rotational modulation. This invention extends the patented technology to multi-dimensional rotational modulation, which can make better use of modulation diversity, combined with time diversity and frequency domain diversity to improve system performance.

The technical innovation of the present invention is: in the modulation process, the OFDM technology and the multi-dimensional rotation modulation technology are adopted comprehensively, and the signal diversity gain is introduced into the rotation modulation constellation diagram, so that the in-phase component ( I-way) and orthogonal component (Q-way) are transmitted independently on the fading channel, and then the two components are interleaved through the set component interleaver to eliminate the correlation of the fading coefficients of the I-way and Q-way, and obtain Gain in modulation diversity; and by choosing the optimal rotation angle for maximum performance gain. In addition, OFDM frequency diversity and interleaving diversity are also introduced, which can effectively improve the performance of the communication system in the transmission of fading channels, and obtain performance advantages over the BICM-OFDM system as a whole. Moreover, the operation steps of the method of the present invention are simple and practical, and the effect is obvious, and can be applied to various coding and modulation schemes, especially for codewords with high code rates and different code lengths, and can well lower the frame error rate of the system, Therefore, the present invention has very good application prospects.

Description of drawings

Fig. 1 is a flow chart of each operation step of the method for joint coding and modulation diversity in an OFDM system according to the present invention.

Figure 2 (a) and (b) are schematic diagrams of time-frequency interleaving rules and Q-way interleaving rules of modulation symbols in Q-way interleaving of four-dimensional rotational modulation, respectively.

Fig. 3(a) and (b) are schematic diagrams of the two-dimensional coordinate system of the QPSK constellation diagram and its rotation, respectively.

Fig. 4 is a schematic diagram of a time slot structure of an OFDM system.

Figure 5(a) and (b) are schematic diagrams of two modes of centralized mode and distributed mode in the OFDM frame structure respectively.

Fig. 6 is a schematic diagram of an OFDM time-frequency resource allocation method in an embodiment of the present invention.

Fig. 7 is a schematic diagram of rules of a time-frequency two-dimensional interleaver.

Fig. 8 is a schematic diagram of a constellation diagram and demodulation formed after channel fading of the rotated constellation diagram.

Fig. 9 (a) and (b) are schematic diagrams comparing two kinds of transmission performance curves of the embodiment of the present invention and the BICM OFDM mode under 8/9 code rate respectively.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Referring to Fig. 1, the specific operation steps of the method for the joint coded modulation diversity of OFDM system are introduced in the present invention, it is to adopt OFDM technology and multi-dimensional rotational modulation technology, through the component interleaving of rotational constellation diagram, modulation symbol, obtain the gain of signal diversity , thereby improving the performance of the system.

Step 1. The sender initializes the send data: encode and modulate the send data of each user according to the set encoding and modulation methods, and then perform modulation on the symbol vector blocks of all users according to the set rotation angle The in-phase component of the I channel and the quadrature component of the Q channel are subjected to multi-dimensional rotation modulation, and then the symbol vector block after the rotation modulation is stored. This step 1 includes the following specific operations:

(11) The transmitting end first calculates the total number of modulation symbols G sent by all users during each transmission: G=OFDM_Num×OFDM_Length, where OFDM_Num is the number of OFDM symbols sent during each OFDM transmission, and OFDM_Length is set at each The number of modulation symbols in OFDM symbols; then calculate the number of modulation symbols S sent by each user: $S=\frac{G}{P},$ In the formula, P is the total number of users at the sending end;

In an embodiment, the selected OFDM frame structure is the frame structure of the TDD mode stipulated in the protocol 3GPP TS 36.211, and the number of modulation symbols contained in each OFDM symbol period is: OFDM_Length=1200 The number of OFDM symbols in each OFDM transmission process The number is: OFDM_Num=12, therefore, the total number of modulation symbols of all users in each transmission process is G=14400, the number of users at the sending end is P=20, and the number of modulation symbols sent by each user is: S=720.

(12) Calculate according to the modulation order M that each modulation symbol is composed of m bit mappings, that is, M=2 ^m , then m=log ₂ M, and calculate the code length N of each user's transmitted data after encoding: N =S × m; then calculate the information bit length K of the transmitted data of each user before encoding: K=r × N, in the formula, the code rate r is a real number whose value range is (0,1];

In the embodiment, QPSK, 16QAM and 64QAM are selected as the modulation methods respectively, so the modulation orders are 4, 16 and 64 respectively, and the information bits corresponding to each modulation symbol are 2, 4 and 6 respectively, thus calculating the The encoded code lengths N of the transmitted data are 1440, 2880 and 4320 respectively.

Since the code rate r of the embodiment is 8/9, the information bit length K generated by each user is 1280, 2560 and 3840 respectively; but, because the encoding scheme in the embodiment of the present invention adopts the protocol 3GPP TS36.212 regulation Turbo encoding, so the information bit length K must conform to the information bit length of Turbo encoding stipulated in the protocol 3GPP TS 36.212. For the information bit length K adopted above, if the information bit length K of the Turbo encoding specified in the protocol 3GPP TS 36.212 is not satisfied, the closest information bit length in the protocol is selected, and then zeros are added at the end of the data to achieve the above The calculated information bit length K is required.

(13) Encode the K-bit information to be sent by each user, and then determine the corresponding Gray mapping constellation pattern according to the code length N bits of each user after encoding according to the modulation mode requirements, and then perform corresponding symbol mapping; and use The symbol vector u _i represents the modulated symbol, then the set of the modulated modulation symbols of the transmitted data of all users, that is, all the symbol vectors is u=(u ₁ , u ₂ ,...,u _G ), and it is called Modulation symbol vector block, where the subscript G is the total number of modulation symbols to be sent by all users;

The embodiment of the present invention adopts Turbo channel coding.

(14) Use the rotation matrix RM to perform multi-dimensional rotation modulation on the modulated symbol vector block to obtain modulation diversity gain: set the symbol vector block x after rotation modulation as: x=(x ₁ , x ₂ , . . . , x _G ), Then each symbol vector x _i in the symbol vector block x satisfies the following formula: x _i ′=RM×u _i ′; where, for N-dimensional rotary modulation, N is a natural number greater than 1, and u _i is N dimensional row vector, representing the modulation symbol before the rotation modulation process, u _i ′ is the transposed column vector of u _i ; x _i is an N-dimensional row vector, representing the modulation symbol after multi-dimensional rotation modulation, xi _′ is x The transposed column vector of _i ; RM is a rotation matrix of order N, the sum of the squares of each row or column is 1, and the row vector or column vector satisfies orthogonality;

The present invention uses the rotation matrix RM to perform multi-dimensional rotation modulation on the modulated symbol vector block. The dimensions include 2-dimensional, 4-dimensional, 8-dimensional or higher dimensions. Complicated, but the advantages are not obvious; therefore, 2-dimensional and 4-dimensional are the most chosen; the specific method is as follows;

When two-dimensional rotational modulation is selected, each two-dimensional modulation symbol vector is composed of an in-phase component and a quadrature component of a modulation symbol, that is, each rotational modulation processes an in-phase component and a quadrature component of a modulation symbol vector; therefore, set Each modulation symbol vector before two-dimensional rotational modulation processing is u _i =A+Bj, wherein, A is the in-phase component of u _i , B is the quadrature component of u _i ; the rotation matrix $\mathrm{RM}=\left(\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right),$ θ is the set rotation angle, and its value range is When the symbol vector processed by two-dimensional rotational modulation is x _i =X+Yj, then $\left(\begin{array}{c}x\\ Y\end{array}\right)=\mathrm{RM}\×\left(\begin{array}{c}A\\ B\end{array}\right),$ Right now $\left(\begin{array}{c}x\\ Y\end{array}\right)=\left(\begin{array}{cc}\cos \mathrm{\θ}& \sin \mathrm{\θ}\\ -\sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right)\left(\begin{array}{c}A\\ B\end{array}\right);$

When the four-dimensional rotation modulation is selected, each four-dimensional modulation symbol is composed of the in-phase component and the quadrature component of two adjacent modulation symbol vectors, that is, each rotation modulation processes the respective in-phase components and quadrature components of two adjacent modulation symbol vectors. Intersecting component; therefore, the two modulation symbol vectors before the four-dimensional rotational modulation processing are respectively A+Bj and C+Dj, and the values corresponding to the two modulation symbol vectors after the four-dimensional rotational modulation are X+Yj and Z+Wj respectively when $\left(\begin{array}{c}x\\ Y\\ Z\\ W\end{array}\right)=\mathrm{RM}\×\left(\begin{array}{c}A\\ B\\ C\\ \mathrm{D.}\end{array}\right),$ In the formula,

$\mathrm{RM}=\left(\begin{array}{cccc}\cos {\mathrm{\θ}}_1\cos {\mathrm{\θ}}_2& \sin {\mathrm{\θ}}_1\cos {\mathrm{\θ}}_2& \cos {\mathrm{\θ}}_1\sin {\mathrm{\θ}}_2& \sin {\mathrm{\θ}}_1\sin {\mathrm{\θ}}_2\\ -\sin {\mathrm{\θ}}_1\cos {\mathrm{\θ}}_2& \cos {\mathrm{\θ}}_1\cos {\mathrm{\θ}}_2& -{\sin \mathrm{\θ}}_1\sin {\mathrm{\θ}}_2& \cos {\mathrm{\θ}}_1\sin {\mathrm{\θ}}_2\\ -\cos {\mathrm{\θ}}_1\sin {\mathrm{\θ}}_2& -\sin {\mathrm{\θ}}_1\sin {\mathrm{\θ}}_2& \cos {\mathrm{\θ}}_1\cos {\mathrm{\θ}}_2& \sin {\mathrm{\θ}}_1\cos {\mathrm{\θ}}_2\\ \sin {\mathrm{\θ}}_1\sin {\mathrm{\θ}}_2& -\cos {\mathrm{\θ}}_1\sin {\mathrm{\θ}}_2& -\sin {\mathrm{\θ}}_1\cos {\mathrm{\θ}}_2& \cos {\mathrm{\θ}}_1\cos {\mathrm{\θ}}_2\end{array}\right),$ θ ₁ and θ ₂ are the set rotation angles respectively, and their value ranges are

图3(b)为图3(a)经过θ度旋转调制后形成的星座图，其中X、Y分别为旋转调制后各星座点在实部轴与虚部轴上的投影，通过旋转调制运算后，X、Y所确定的星座点数值等价于图3(a)顺时针旋转θ度。本发明实施例中，二维四相移相键控QPSK调制的θ取值为 $\mathrm{\θ}=\arctan \left(\frac{1}{2}\right)=0.4636$ (弧度)，旋转因子cosθ＝0.8944，sinθ＝0.4472，假设旋转调制前的符号为A+Bj，旋转调制后的符号为X+Yj，则根据 $\left(\begin{array}{c}X\\ Y\end{array}\right)=\left(\begin{array}{cc}0.8944& 0.4472\\ -0.4472& 0.8944\end{array}\right)\left(\begin{array}{c}A\\ B\end{array}\right),$ 能够得到旋转调制后的符号为；采用16QAM的θ取值为 $\mathrm{\θ}=\arctan \left(\frac{1}{3}\right)=0.3218$ (弧度)；采用64QAM的θ取值为 $\mathrm{\θ}=\arctan \left(\frac{1}{4}\right)=0.245$ (弧度)；从而得到如下的旋转调制矩阵：Referring to FIG. 3 , taking two-dimensional quadrature phase-shift keying QPSK modulation as an example, the comparison of constellation diagrams before and after rotation modulation is introduced. Because QPSK maps every 2 bits into a symbol vector, there are 4 possible bit combinations and corresponding symbol vector values. Figure 3(a) shows the Gray mapping constellation diagram in the case of common modulation, where A, B are the projections of each constellation point on the real part axis and the imaginary part axis respectively, and their values are respectively

Figure 3(b) is the constellation diagram formed after the rotation modulation of Figure 3(a) by θ degrees, where X and Y are the projections of each constellation point on the real part axis and the imaginary part axis after the rotation modulation, respectively, through the rotation modulation operation Afterwards, the constellation point values determined by X and Y are equivalent to the clockwise rotation of θ degrees in Figure 3(a). In the embodiment of the present invention, the value of θ of two-dimensional quadrature phase-shift keying QPSK modulation is $\mathrm{\θ}=\arctan \left(\frac{1}{2}\right)=0.4636$ (radian), rotation factor cosθ=0.8944, sinθ=0.4472, assuming that the symbol before rotation modulation is A+Bj, and the symbol after rotation modulation is X+Yj, then according to $\left(\begin{array}{c}x\\ Y\end{array}\right)=\left(\begin{array}{cc}0.8944& 0.4472\\ -0.4472& 0.8944\end{array}\right)\left(\begin{array}{c}A\\ B\end{array}\right),$ The symbol after rotation modulation can be obtained; the value of θ using 16QAM is $\mathrm{\θ}=\arctan \left(\frac{1}{3}\right)=0.3218$ (radian); the value of θ using 64QAM is $\mathrm{\θ}=\arctan \left(\frac{1}{4}\right)=0.245$ (radian); thus the following rotation modulation matrix is obtained:

(15) Store the symbol vector block x after the rotational modulation processing into the memory.

Step 2. The sending end allocates OFDM time-frequency resources to the symbol vector blocks of all users in the memory according to the set OFDM mode, distributes the symbol vector blocks of each user to each OFDM symbol in sequence, and then distributes the symbol vector blocks in the OFDM symbol Each user's symbol vector block is subjected to Q-way interleaving.

This step 2 includes the following specific operations:

(21) The sender assigns OFDM time-frequency resources to the symbol vector block x of all users according to the set centralized or distributed OFDM mode, where the time resource is the time slot in which OFDM symbols are sent sequentially, and the frequency resource is the time slot for sending each Subcarrier bandwidth occupied by OFDM symbols; each OFDM symbol occupies a time slot, and each modulation symbol in an OFDM symbol occupies a subcarrier, so the number of modulation symbols OFDM_Length included in each OFDM symbol is also each OFDM The number of subcarriers occupied by symbols; that is, the number of modulation symbols L of each user included in each OFDM symbol is set to: $L=\frac{\mathrm{OFDM}\_\mathrm{Length}}{P}=\frac{S}{\mathrm{OFDM}\_\mathrm{Num}};$ In the formula, OFDM_Length is the number of all modulation symbols in each OFDM symbol, P is the total number of all users, S is the number of modulation symbols sent in each transmission of each user, OFDM_Num is the number of modulation symbols sent in each OFDM transmission The number of OFDM symbols; so that each OFDM symbol includes L×P modulation symbols, which occupy OFDM_Length subcarriers in the frequency domain; there are OFDM_Num OFDM symbols in total, and occupy OFDM_Num time slots in the time domain.

Referring to Fig. 4, in the embodiment of the present invention, $N_{\mathrm{sc}}^{\mathrm{RB}}=12,$ N _symb =6, N _RB =100, T _slot =5 ms. This embodiment operates two time slots together, so in each OFDM transmission process, the number of OFDM symbols OFDM_Num=12, the number of modulation symbols included in each OFDM symbol OFDM_Length=1200, regardless of whether it is centralized or distributed, Both store the symbol vector block of the user in the time slot structure as shown in Figure 4. After the allocation of the above-mentioned OFDM time-frequency resources, the 720 modulation symbols of each user are evenly distributed on 12 OFDM symbols, that is, each OFDM symbol Both contain 60 modulation symbols for each user.

Referring to Fig. 5(a), the method of writing the user symbol vector block into the time slot structure according to the centralized OFDM mode is introduced. In the figure, the same block of shading represents the symbol vector block of the same user, and the L=720 symbols in the same user symbol vector block are divided into $N_{\mathrm{sc}}^{\mathrm{RB}}=12$ Divided into one group, a total of 60 groups; each block in the figure represents a group containing 12 modulation symbols. After the user's symbol vector blocks are divided into groups, the same user's symbol vector blocks are divided into 5 groups in a column. Arranged sequentially, there are 2×N _symb columns in total, that is, the 60 group blocks of each user can be converted into a 5×12 matrix, and each element of the matrix is a group including 12 modulation symbols. By analogy, after the symbol vector blocks of 20 users are arranged in the above-mentioned manner, a 100×12 matrix is formed, and then as shown by the arrows, the grouping blocks are taken out in column order and stored in the time slot structure in Figure 3(a) in memory.

Referring to Fig. 5(b), the method of writing user symbol vector blocks into the time slot structure according to the distributed OFDM mode is introduced. First group the user's symbol vector blocks into groups of 12 modulation symbols according to the same method as above, and then arrange the 60 group blocks of each user in row order, and each user's symbol vector blocks are converted into 1×60 matrix, then the symbol vector blocks of 20 users form a 20×60 matrix, and then they are taken out in column order as shown by the arrow. That is, after taking out the first group of each user in turn, continue to take out the second group of each user, and so on, until the 60th group of 20 users is taken out.

(22) According to the dimensions of the multi-dimensional rotational modulation selected in the preceding steps, perform corresponding Q-way interleaving processing on each user's symbol vector block in the OFDM symbol: time-frequency interleaving of modulated symbol vectors, Q-way frequency-domain interleaving and Q channel time-frequency two-dimensional interleaver for interleaving.

When the sending end performs Q-way interleaving according to the centralized OFDM mode, if two-dimensional rotational modulation is used, then in step (22), the operations of time-frequency interleaving and Q-way frequency domain interleaving of the modulation symbol vector are not performed, and are directly performed The interleaving operation of the Q-way time-frequency two-dimensional interleaver; if four-dimensional or higher-dimensional rotational modulation is adopted, then the step (22) includes the following operations:

格式的交织器后，再按照逐列方式取出，以通过该符号矢量的时频交织变换，减小每次旋转调制中两个相邻符号矢量间的时域和频域的相关性，式中，D为多维旋转调制的维数。(221) The transmitting end performs time-frequency interleaving processing on the rotationally modulated symbol vector of the same user in each OFDM symbol period, and the time-frequency interleaving rule is: the rotationally modulated symbol vector of each user is written in a row-by-row manner save at

After the interleaver of the format, it is taken out in a column-by-column manner, so as to reduce the time-domain and frequency-domain correlation between two adjacent symbol vectors in each rotational modulation through the time-frequency interleaving transformation of the symbol vector, where , D is the dimensionality of multi-dimensional rotation modulation.

的两个频率上，使得这两个符号相隔30个符号的间隔，从而减小一次四维旋转调制处理中两个相邻符号间的时域和频域的相关性。In the embodiment, if two-dimensional rotational modulation is used, step (221) is not performed; if four-dimensional rotational modulation is adopted, time-frequency interleaving of modulation symbols is performed according to step (221), and two simultaneous processing of one four-dimensional rotational modulation is carried out. Symbols are scattered at intervals

On the two frequencies, the two symbols are separated by an interval of 30 symbols, thereby reducing the time-domain and frequency-domain correlation between two adjacent symbols in a four-dimensional rotation modulation process.

的D个符号矢量的Q路分量设为一组，共有组；再将每组内的Q路分量依序向右循环移动一位，即Q_f移动至

位置，而

移动至

位置，

则移动至

位置，相应地，最后一位Q路分量则移至Q_f位置，也就是：Q_f→Q_f+L/D→Q_f+2L/D→Q_f+3L/D→…→Q_f；然后再将I路同相分量和移位后的Q路正交分量合并组成新的符号矢量。(222) Perform frequency-domain interleaving processing on the Q-way orthogonal components of the time-frequency interleaved symbol vectors of each user in each OFDM symbol period in sequence, and the frequency-domain interleaving rule is for each OFDM symbol belonging to the same user The L modulation symbol vectors are processed together: firstly, among the L symbol vectors, the interval is

The Q-path components of the D symbol vectors are set as a group, and there are group; and then move the Q-way components in each group to the right in order, that is, Q _f moves to

location, while

move to

Location,

then move to

Correspondingly, the last Q-way component is moved to the Q _f position, that is: Q _f →Q _f+L/D →Q _f+2L/D →Q _f+3L/D →...→Q _f ; Then, the in-phase component of the I channel and the quadrature component of the Q channel after shifting are combined to form a new symbol vector.

In an embodiment, if two-dimensional rotational modulation is adopted, step (222) is not performed; if four-dimensional rotational modulation is adopted, frequency-domain interleaving of Q-path components is performed. Among the 60 modulation symbols of the same user in each OFDM symbol, the Q-path components of the four modulation symbols with an interval of 15 symbols are taken as a group, and the Q-path components in this group are sequentially shifted to the right, namely : Q ₁ →Q ₁₅ →Q ₃₀ →Q ₄₅ →Q ₁ , and perform the same operation on each of the other groups in turn.

个时隙和频域上

个子载波带宽距离的符号。(223) According to the set time-frequency two-dimensional interleaving rule, each user is evenly distributed in each OFDM symbol and all S modulation symbols sent each time are interleaved, so that each user after interleaving sends The quadrature component and its in-phase component of any one of the S modulation symbols are as uncorrelated as possible in time and frequency, even if the distance between the quadrature component and its in-phase component is as far as possible. In the time domain, one OFDM symbol occupies one time slot in time, and according to the time-frequency resources occupied by the S symbols of the same user, in the time domain, the positions are separated by OFDM_Num time slots, that is, two frequency slots are separated by OFDM_Num OFDM symbols. The distance between the points is the farthest, and the correlation is the weakest; in the frequency domain, the distance between two signal points that are separated by L subcarrier bandwidths, that is, the distance between L symbols, is the farthest, and the correlation is the weakest. However, for Ensure that all frequency points can be evenly divided into steps, and the selection satisfies the time domain at the same time

time slot and frequency domain

symbols with a subcarrier bandwidth distance.

When the sending end performs Q-way interleaving according to the distributed OFDM mode, first calculate the result of step (22) according to the operation rules of the above-mentioned centralized OFDM mode, and then perform the centralized calculation result in the frequency domain according to the step (21) The distributed frequency point allocation method spreads the results evenly, the position in the time domain remains unchanged, and the relative position in the frequency domain does not change, but the absolute position of the frequency point of the subcarrier is changed.

个OFDM符号的第

个OFDM符号内第f₂个调制符号的Q路分量；接着选取第2个OFDM符号内第f₁个调制符号的Q路分量，再选取在第

个OFDM符号内第f₂个调制符号的Q路分量，继续选取第3个OFDM符号内第f₁个调制符号的Q路分量，再选取第

个OFDM符号内第f₂个调制符号的Q路分量，依次类推，按照在时域上，从第1个OFDM符号选起，再选择与它相隔

个OFDM符号的第

个OFDM符号，然后再增加一个选择第2个OFDM符号，再选择与它相隔个OFDM符号的第个OFDM符号，依次类推，一直选择到从第

个OFDM符号，再选择与它相隔个OFDM符号的第(OFDM_Num)个OFDM符号，在频域上，就是f₁、f₂交替选择；这样，在交织前，每个OFDM符号中的各个调制符号的Q路分量的位置坐标分别为：The time-frequency two-dimensional interleaving rule of the present invention is as follows: the modulation symbols of the same user separated by W subcarrier bandwidths in the frequency domain are set as a group, and then assuming that two subcarriers with serial numbers f ₁ and f ₂ are selected, Wherein, f ₂ =f ₁ +W, W is the bandwidth interval of two subcarrier frequency points f ₁ and f ₂ ; $W=\frac{L}{2},$ And let the position coordinates of the Q-path component of each modulation symbol be (f, t), which means that the fth modulation symbol in each OFDM symbol is located at the fth subcarrier frequency point in the frequency domain and the tth subcarrier frequency point in the time domain In one OFDM symbol, the natural number t is the sequence number of the OFDM symbol, and its maximum value is OFDM_Num; first select the Q-path component of the modulation symbol in order, that is, first select the Q-path component of the _f1th modulation symbol in the first OFDM symbol, and then Choose intervals in the time domain

The first OFDM symbol

The Q component of the f ₂ modulation symbol in the first OFDM symbol; then select the Q component of the f 1 modulation symbol in the second OFDM symbol, and then select the Q component of the f ₁ modulation symbol in the second OFDM symbol

The Q component of the f ₂ modulation symbol in the first OFDM symbol, continue to select the Q component of the f 1 modulation symbol in the third OFDM symbol, and then select the Q component of the f ₁ modulation symbol in the third OFDM symbol

The Q-path component of the _f2th modulation symbol in the first OFDM symbol, and so on, according to the time domain, start from the first OFDM symbol, and then select the distance from it

The first OFDM symbol

OFDM symbols, and then add another one to select the second OFDM symbol, and then choose to be separated from it The first OFDM symbol OFDM symbols, and so on, until the first

OFDM symbols, and then choose to be separated from it The (OFDM_Num)th OFDM symbol of the first OFDM symbol, in the frequency domain, is that f ₁ and f ₂ are alternately selected; like this, before interleaving, the position coordinates of the Q-path components of each modulation symbol in each OFDM symbol are respectively :

约为OFDM符号的时域长度OFDM_Num×T_s的一半，其中，T_s是OFDM符号的传输时间；频域间隔为相应的OFDM系统的频域长度的二分之一；从而使得计算复杂度低的时频二维交织能充分有效地利用OFDM系统的频率分集和时间分集，并与调制分集实现联合优化。 $\{(f_1,1),(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+1),(f_1,2),(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+2),\·\·\·,(f_1,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}),(f_2,\mathrm{OFDM}\_\mathrm{Num})\},$ After the time-frequency two-dimensional interleaving of the Q-path components, the position coordinates of the frequency domain and time domain occupied by it are just the result of the Q-path components of the original OFDM symbol moving one bit to the right in sequence, that is, $\{(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+1),(f_1,2),(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+2),\&Center\; Dot;\&Center\; Dot;\·,(f_1,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}),(f_2,\mathrm{OFDM}\_\mathrm{Num}),(f_1,1)\};$ Therefore, the minimum time interval between the I-way component and the Q-way component after time-frequency two-dimensional interleaving is

About half of the time domain length OFDM_Num×T _s of OFDM symbols, where T _s is the transmission time of OFDM symbols; the frequency domain interval is half of the frequency domain length of the corresponding OFDM system; thus making the computational complexity low The time-frequency two-dimensional interleaving can fully and effectively utilize the frequency diversity and time diversity of the OFDM system, and achieve joint optimization with modulation diversity.

Referring to Fig. 7, the time-frequency two-dimensional interleaving rule that the embodiment of the present invention adopts in this step (223) is introduced, and this figure is wherein the schematic diagram of Q path interleaving, and the specific method is: each user is evenly distributed in each OFDM symbol The Q-path components of the symbol vector block are interleaved; in the embodiment, the symbol vector block of each user includes S=720 modulation symbols, which are evenly distributed in 12 OFDM symbols according to the time domain resources, and each OFDM symbol includes each The 60 modulation symbols of the user, that is, the frequency domain resource occupied by the Q-path component for time-frequency interleaving is 60 subcarriers, and the time domain resource is 12 OFDM symbols; The frequency points with an interval of ≥5 OFDM symbols in the domain are taken as a group; the subcarrier bandwidth numbers are f ₁ , f ₂ , where f ₁ =1...60, f ₂ =(f ₁ +30)mod 60; And let (f, t) represent that the Q-path component of the modulation symbol occupies the fth subcarrier in the frequency domain, and occupies the tth OFDM symbol in the time domain, t=1, 2...12; then in the time and In terms of frequency, the imaginary part of the symbol is exchanged according to the following rules: (f ₁ , 1)→(f ₂ , 7), (f ₂ , 7)→(f ₁ , 2), (f ₁ , 2)→( f ₂ , 8), (f ₂ , 8) → (f ₁ , 3), (f ₁ , 3) → (f 2 , 9), (f ₂ , 9) → (f _{1 ,} 4), (f ₁ , 4) → (f ₂ , 10), (f ₂ , 10) → (f ₁ , 5), (f ₁ , 5) → (f ₂ , 11), (f ₂ , 11) → (f ₁ , 6), (f ₁ , 6) → (f ₂ , 12), (f ₂ , 12) → (f ₁ , 1).

Step 3. According to the preset OFDM modulation length and IFFT operation length, the sending end pads the bit length of each OFDM symbol that is less than the IFFT operation length with zeros, and then performs IFFT operations and addition on each OFDM symbol after zero padding. OFDM processing of the cyclic prefix CP and then sending the data.

This step 3 includes the following specific operations:

(31) After the bit length less than the length of the IFFT operation in each OFDM symbol is filled with zeros, then each OFDM symbol after the zeros is filled with IFFT according to the following formula: $x\left(\mathrm{no}\right)=\frac{1}{\sqrt{N}}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(k\right){\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">e</figure-callout>}}^j,$ In the formula, N is the number of subcarriers, X(k) is the complex signal under the set modulation mode, x(n) is the sampling of OFDM symbols in the time domain, and the imaginary number unit j is defined as: j ² =-1, k is the serial number of the symbol vector in the OFDM symbol, and its value range is a non-negative integer of [0, N-1].

Referring to FIG. 6 , the allocation of OFDM time-frequency resources in the embodiment of the present invention is further introduced: the horizontal axis represents the allocation of OFDM symbols on subcarrier bandwidth, and the vertical axis represents the allocation of OFDM symbols on time slots. The length of each OFDM symbol shown in Figure 4 is 1200, and each OFDM transmission process processes 12 OFDM symbols, occupying 2048 OFDM subcarrier bandwidths; the length of the FFT or IFFT selected by this embodiment is 2048, after reallocation The length of each OFDM symbol in is 1200 modulation symbols, and 848 zeros are added to make its length equal to the length 2048 of the IFFT.

(32) Add CP to each OFDM symbol after the IFFT operation to eliminate inter-symbol interference caused by multipath channel transmission; the specific operation content is: add μ symbol copies at the end of each OFDM symbol to the OFDM symbol Front end, where μ is the length of the CP.

The CP length μ in the embodiment is 512, and the symbol bit length after adding the CP processing is increased to 2560.

(33) Send each OFDM symbol in sequence.

Step 4. After the receiving end receives the data, it first performs OFDM processing to remove CP and fast Fourier transform FFT operation on the data block symbols, then performs phase compensation and zero removal, and then performs Q-path resolution on the obtained OFDM symbols in turn Interleaving, OFDM solution time-frequency resource allocation, rotation demodulation and decoding, to obtain the required data information. This step 4 includes the following specific operations:

(41) After the receiving end receives the data, it performs OFDM processing: first remove the CP for each OFDM symbol received, and delete the head μ symbols of each OFDM symbol received; then for each OFDM symbol The OFDM symbols are respectively subjected to the fast Fourier transform FFT operation according to the following formula: $x\left(k\right)=\frac{1}{\sqrt{N}}\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(\mathrm{no}\right)e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;}}{N}\mathrm{k\; n}},$ In the formula, N is the number of subcarriers, X(k) is the complex signal under the set modulation mode, x(n) is the sampling of OFDM symbols in the time domain, and the imaginary number unit j is defined as: j ² =-1, k is the serial number of the symbol vector in the OFDM symbol, and its value range is a non-negative integer of [0, N-1]; then, the converted OFDM symbol is stored;

In the embodiment, 512 cyclic prefixes of the headers of 2560 symbols received each time are deleted.

(42) Phase compensation is carried out to the transformed OFDM symbols, so that the influence of multipath transmission on data is eliminated according to the channel estimation value; the phase compensation formula is: $\mathrm{the\; y}\left(t\right)=\frac{x\left(t\right)\&times;\stackrel{\&OverBar;}{h\left(t\right)}}{\left|h\left(t\right)\right|};$ where x(t) is the symbol vector in each OFDM symbol, h(t), h(t) and |h(t)| are the channel estimate, the conjugate and modulus of the channel estimate, respectively;

(43) divide each OFDM symbol after the phase compensation by zero, that is, delete the zero added by the step (31) for matching the bit length of the IFFT operation length, and then store each OFDM symbol;

This step in the embodiment is to remove the 848 zero bits added to match the IFFT length.

(44) According to the multi-dimensional rotation modulation selected in step (13) and the centralized or distributed OFDM mode selected in step (21), carry out corresponding Q-path deinterleaving processing to the symbol vector in each OFDM symbol, that is, according to the steps The corresponding rules of (22) are reversed.

When the receiving end performs Q-way deinterleaving according to the centralized OFDM mode, if two-dimensional rotational modulation is used, then in the step (44), only the de-interleaving operation of the Q-way time-frequency two-dimensional interleaver is performed, and the modulation symbols are not performed. The operation of vector time-frequency deinterleaving and Q-way frequency domain deinterleaving; if four-dimensional or higher-dimensional rotation modulation is adopted, then this step (44) includes the following operations:

个OFDM符号内第f₂个调制符号的Q路分量，再选取第2个OFDM符号内第f₁个调制符号的Q路分量，接着选取第

个OFDM符号内第f₂个调制符号的Q路分量，再选取第3个OFDM符号内第f₁个调制符号的Q路分量，继续选取第

个OFDM符号内第f₂个调制符号的Q路分量，然后选取第3个OFDM符号内第f₁个调制符号的Q路分量，依次类推；在时域上按照从第

个OFDM符号选起，再选择第2个OFDM符号，接着选择与它相隔

个OFDM符号第

个OFDM符号，再选择从第2个增加1个OFDM符号的第3个OFDM符号，然后选择与它相隔

个OFDM符号第

个OFDM符号，依次类推，选择到从第个OFDM符号，再选择与它相隔个OFDM符号的第(OFDM_Num)个OFDM符号，最后选取第1个OFDM符号；在频域上是f₂、f₁交替选择；这样，在交织前，每个OFDM符号中的各个调制符号的Q路分量的位置坐标分别为：(441) According to the reverse processing method of the time-frequency two-dimensional interleaving rule in step (223), deinterleave the Q-path components of the symbol vector: first select the Q-path components of the modulation symbols in order, that is, first select the first

The Q component of the f _2th modulation symbol in the first OFDM symbol, and then select the Q component of the f 1th modulation symbol in the second OFDM symbol, and then select the Q component of the f _1st modulation symbol in the second OFDM symbol

The Q-path component of the _f2th modulation symbol in the first OFDM symbol, and then select the Q-path component of the _f1th modulation symbol in the third OFDM symbol, and continue to select the first

The Q-path component of the _f2th modulation symbol in the first OFDM symbol, and then select the Q-path component of the _f1th modulation symbol in the third OFDM symbol, and so on;

Select the first OFDM symbol, then select the second OFDM symbol, and then select the distance from it

OFDM symbol No.

OFDM symbols, then select the third OFDM symbol that increases by 1 OFDM symbol from the second, and then select the distance from it

OFDM symbol No.

OFDM symbols, and so on, select from the first OFDM symbols, and then choose to be separated from it The (OFDM_Num)th OFDM symbol of the first OFDM symbol, finally select the first OFDM symbol; in the frequency domain, f ₂ and f ₁ are alternately selected; like this, before interleaving, the Q of each modulation symbol in each OFDM symbol The position coordinates of the road components are:

$<span\; class="notranslate">\; \{</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="Num"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">Num</figure-callout></span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="Num"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">Num</figure-callout></span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ,</span>$

After the time-frequency two-dimensional deinterleaving of the Q-path component, the position coordinates of the frequency domain and time domain occupied by it are exactly the result of the Q-path component of the original OFDM symbol moving one bit to the left in sequence, which is:

$<span\; class="notranslate">\; \{</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="Num"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">Num</figure-callout></span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="Num"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">Num</figure-callout></span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span>$

So that the quadrature component symbols of the Q path are exchanged according to the above rules in time and frequency

$<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Right\; Arrow;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Right\; Arrow;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

$<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Right\; Arrow;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Right\; Arrow;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

$<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\frac{\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Right\; Arrow;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; OFDM</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; Num</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Right\; Arrow;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="f"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

(f ₁ , 2)→(f ₂ , OFDM_Num/2+1), (f ₂ , OFDM_Num/2+1)→(f ₁ , 1).

In the embodiment, according to the step (451) to solve the Q-way time-frequency two-dimensional interleaving is to match and restore the imaginary part and the real part originally belonging to the same modulation symbol. The frequency points whose upper interval is greater than or equal to 5 OFDM symbols are taken as a group; the subcarrier bandwidth numbers are f ₁ , f ₂ , where f ₁ =1...60, f ₂ =(f ₁ +30)mod 60; And let (f, t) represent that the symbol Q component occupies the fth subcarrier in the frequency domain, and occupies the tth OFDM symbol in the time domain, t=1, 2, ..., 12; then in the time and frequency above, the imaginary part of the symbol is exchanged according to the following rules: (f ₁ , 1)→(f ₂ , 12), (f ₂ , 12)→(f ₁ , 6), (f ₁ , 6)→(f ₂ , 11), (f ₂ , 11)→(f ₁ , 5), (f ₁ , 5)→(f 2 , 10), (f ₂ , 10)→(f _{1 ,} 4), (f ₁ , 4) → (f ₂ , 9), (f ₂ , 9) → (f ₁ , 3), (f ₁ , 3) → (f ₂ , 8), (f ₂ , 8) → (f ₁ , 2 ), (f ₁ , 2) → (f ₂ , 7), (f ₂ , 7) → (f ₁ , 1).

(442) According to the reverse processing method of step (222), the Q path component of the symbol vector is de-frequency-domain interleaved, and its rule is: in each OFDM symbol, in the L symbol vectors of the same user, the interval is The Q-path components of the D symbol vectors in the group are set as a group, and the Q-path components in the group are sequentially shifted to the left by one bit, and then the imaginary part and the real part that originally belonged to the same symbol vector are matched and restored.

In the embodiment, if two-dimensional rotational modulation is adopted, this step (452) is not performed; if four-dimensional rotational modulation is adopted, the specific method for solving the Q-way frequency domain interleaving according to this step (452) is: the same user in one OFDM symbol The 60 symbols in the symbol vector of , the Q-path components of four symbols with an interval of 15 are taken as a group, and the Q-path components in this group are shifted to the left in turn, and the imaginary part and The real part is matched and restored, and the same operation is performed on the Q-path components of the other groups in turn.

格式的交织器后，再按照逐行方式取出，这样，在符号矢量块内相隔

的两个符号就被还原放在相邻位置，完成符号矢量的时频解交织变换。(443) Carry out time-frequency deinterleaving to the symbol vector according to the reverse processing method of step (221), the rule is: the symbol vector of each user is stored in the

After the interleaver of the format, it is taken out in a row-by-row manner, so that the interval in the symbol vector block

The two symbols of are restored and placed in adjacent positions to complete the time-frequency deinterleaving transformation of the symbol vector.

In the embodiment, if two-dimensional rotational modulation is adopted, this step (453) is not performed, and if four-dimensional rotational modulation is adopted, the specific method for solving the time-frequency interleaving according to this step (453) is: each user in an OFDM symbol Within the 60 modulation symbols, the two symbols scattered at an interval of 30 are placed in adjacent positions, thereby restoring the positions of the four components before a four-dimensional rotational modulation process.

(45) Continue to perform OFDM solution time-frequency resource allocation operation: all L×P modulation symbols in all OFDM symbols allocated to each user on the OFDM time-frequency resource in step (21) according to the reverse operation sequence of this step, Revert back to serial for all user's sign vectors.

(46) Use the maximum likelihood demodulation method to rotate and demodulate the symbol vector after OFDM solution time-frequency resource allocation: take the rotated constellation diagram after the multipath channel as the demodulation reference constellation diagram, and calculate the received symbol vector set The Euclidean distance between each symbol vector in and each constellation point in the reference constellation diagram is mapped to the log-likelihood ratio of each bit of each symbol vector for decoding.

Referring to FIG. 8 , it introduces the constellation diagram and its demodulation method formed after the fading channel is passed through the rotating modulation constellation diagram. In the figure, the signals of the I channel and the Q channel have different channel fading amplitude distortions respectively. Let the channel fading amplitude coefficient of the I channel be |h2|, and the channel fading amplitude coefficient of the Q channel be |h1|. The demodulation method is as follows: first calculate the distance from the receiving point to each constellation point, that is, d ₁ ~ d ₄ shown in the figure, and then calculate the logarithmic likelihood ratio of each bit corresponding to the symbol. Taking the first bit as an example, according to the constellation diagram, the combination of bits whose first bit is 0 among the four constellation points is 00 and 01, and the corresponding distances are d ₁ and d ₄ , and the bit combination whose first bit is 1 are 10 and 11, and the corresponding distances are d ₂ and d ₃ ; thus the log likelihood ratio of this bit is:

$\mathrm{<span\; class="notranslate">\; log</span>}\frac{\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\frac{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="d"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">d</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\frac{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="4"\; label="d"\; filenames="H2009100911634E00012.png,H2009100911634E00042.png"\; state="\{\{state\}\}">d</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\frac{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="3"\; label="d"\; filenames="H2009100911634E00042.png,H2009100911634E00051.png"\; state="\{\{state\}\}">d</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\frac{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="d"\; filenames="H2009100911634E00011.png,H2009100911634E00012.png"\; state="\{\{state\}\}">d</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; .</span>$

(47) Select a corresponding decoding method according to the coding method, decode and restore each group of OFDM symbols into information bits with a length of K bits, and the whole process ends.

The test of the embodiment of the present invention completed by the applicant adopts Turbo as its channel coding. The various parameters of this embodiment are described as follows: the code rate is 8/9, the channel model is TU; the decoding method is Log-Map; the maximum number of iterations=8; the IFFT length or FFT length is 2048, and the CP length is 512; the modulation method Under the QPSK condition, the information bit length is 1280; the modulation mode is under the 16QAM condition, the information bit length is 2560; the modulation mode is under the 64QAM condition, the information bit length is 3840.

Figure 9(a) and (b) are the comparison diagrams of the transmission performance curves at code rate 8/9 of the embodiment of the present invention and the currently commonly used BICMOFDM mode, both of which adopt Turbo coding. Fig. 9(a) is a performance curve under the centralized QPSK mode frame structure. Comparing the curves in Figure 9(a), when using QPSK, when the frame error rate is 10E-2, the performance of the four-dimensional rotational modulation OFDM Turbo is nearly 5 dB higher than that of the bit-interleaved coding modulation OFDM Turbo. Compared with OFDM Turbo with bit-interleaved coding modulation, the performance improvement of OFDM Turbo with dimensional rotation modulation is also greater than 3.5 dB, that is, an improvement of nearly 4 dB. Fig. 9(b) is a performance curve under the frame structure of 16QAM distributed QPSK mode. Comparing the curves in Figure 9(b), when 16QAM is used, when the frame error rate is 10E-2, the performance of the four-dimensional rotational modulation OFDM Turbo is nearly 4dB higher than that of the bit-interleaved coding modulation OFDM Turbo, and the two-dimensional The performance improvement of rotationally modulated OFDM Turbo over bit-interleaved coded modulated OFDM Turbo is also 3dB.

Therefore, test of the present invention is successful, has realized the purpose of the invention.

Claims (8)

1. method that is used for the modulation diversity joint codes of orthogonal frequency ofdm system is characterized in that described method comprises following operating procedure:

(1) transmitting terminal carries out initialization process to sending data: each user's transmission data are encoded respectively and modulate according to the coding of setting and modulation system, according to the anglec of rotation of setting I road in-phase component and the Q road quadrature component of the symbolic vector piece of all users after modulating are carried out four-dimensional rotation modulation again, then the symbolic vector piece behind the rotation modulation is stored;

(2) transmitting terminal is according to the symbolic vector piece distribution OFDM running time-frequency resource of the OFDM pattern of setting to all users in the memory, each user's symbolic vector piece is evenly distributed in each OFDM symbol successively, again the symbolic vector piece of each user in the OFDM symbol is carried out Q road interleaving treatment;

(3) transmitting terminal is according to default OFDM modulation length and inverse fast fourier transform IFFT computing length, respectively to not enough IFFT computing length in each OFDM symbol the position long zero padding, again each the OFDM symbol after the zero padding is comprised the IFFT computing and add the OFDM processing of cyclic prefix CP, then send data;

(4) behind the receiving terminal receive data, first this data block symbols is removed the solution OFDM processing of CP and fast Fourier transform FFT computing, carry out again phase compensation and zero-suppress, then the OFDM symbol that obtains is carried out the deinterleaving of Q road, OFDM solution time-frequency resource allocating, rotation solution mediation decoding successively, obtain required data message, wherein

Described step (1) further comprises following content of operation:

(11) transmitting terminal calculates first the total G:G=OFDM_Num * OFDM_Length of the modulation symbol that all users send in each transmission course, in the formula, OFDM_Num is the OFDM symbolic number that sends in each OFDM transmission course, and OFDM_Length is the modulation symbol number that arranges in each OFDM symbol; Calculate again the modulation symbol of each user's transmission and count S:

In the formula, P is the total number of users of transmitting terminal;

(12) calculate each modulation symbol according to order of modulation M and formed by m bit mapping, be i.e. M=2 ^m, m=log then ₂M, the code length N:N=S of the transmission data of calculating each user behind coding * m; The information bit position long K:K=r * N of the transmission data of calculating again each user before coding, in the formula, code check r be span be (0,1] real number;

The K bit information that (13) will send each user is encoded, and the code length N bit of each user after will encoding again behind definite corresponding gray mappings constellation pattern, carries out corresponding sign map according to the modulating mode requirement; And use symbolic vector u _iSymbol after the expression modulation, then the modulation symbol of all users' transmission data after modulation, be that the set that whole symbolic vectors form is u=(u ₁, u ₂..., u _G), and be called the modulation symbol vector block, in the formula, the sum of the modulation symbol that subscript G is ready for sending for all users;

(14) the symbolic vector piece after adopting spin matrix RM to modulation carries out four-dimensional rotation modulation, obtains the modulation diversity gain: the symbolic vector piece x that establishes behind the rotation modulation is: x=(x ₁, x ₂..., x _G), each symbolic vector x among this symbolic vector piece x then _iAll satisfy following formula: x _i'=RM * u _i'; In the formula, u _iFour-dimensional row vector, the modulation symbol before the expression rotation modulation is processed, u _i' be u _iThe transposition column vector; x _iFour-dimensional row vector, the modulation symbol behind the expression multidimensional rotation modulation, x _i' be x _iThe transposition column vector; RM is the spin matrix of quadravalence, and the quadratic sum of its every row or every row all is 1, satisfies orthogonality between row vector or the column vector;

Each four-dimensional modulation symbol is that in-phase component and the quadrature component by two adjacent modulation symbol vectors consisted of, and namely each rotation modulation is processed two adjacent modulation symbol vectors in-phase component and quadrature component separately; So two modulation symbol vectors establishing before four-dimensional rotation modulation is processed are respectively A+Bj and C+Dj, when being respectively X+Yj and Z+Wj through these two values corresponding to modulation symbol vector behind the four-dimensional rotation modulation, then

$\left(\begin{array}{c}X\\ Y\\ Z\\ W\end{array}\right)=\mathrm{RM}\&times;\left(\begin{array}{c}A\\ B\\ C\\ D\end{array}\right),$ In the formula,

$\mathrm{RM}=\left(\begin{array}{cccc}\cos {\mathrm{\&theta;}}_1\cos {\mathrm{\&theta;}}_2& \sin {\mathrm{\&theta;}}_1\cos {\mathrm{\&theta;}}_2& \cos {\mathrm{\&theta;}}_1\sin {\mathrm{\&theta;}}_2& \sin {\mathrm{\&theta;}}_1\sin {\mathrm{\&theta;}}_2\\ -\sin {\mathrm{\&theta;}}_1\cos {\mathrm{\&theta;}}_2& \cos {\mathrm{\&theta;}}_1\cos {\mathrm{\&theta;}}_2& -\sin {\mathrm{\&theta;}}_1\sin {\mathrm{\&theta;}}_2& \cos {\mathrm{\&theta;}}_1\sin {\mathrm{\&theta;}}_2\\ -\cos {\mathrm{\&theta;}}_1\sin {\mathrm{\&theta;}}_2& -\sin {\mathrm{\&theta;}}_1\sin {\mathrm{\&theta;}}_2& \cos {\mathrm{\&theta;}}_1\cos {\mathrm{\&theta;}}_2& \sin {\mathrm{\&theta;}}_1\cos {\mathrm{\&theta;}}_2\\ \sin {\mathrm{\&theta;}}_1\sin {\mathrm{\&theta;}}_2& -\cos {\mathrm{\&theta;}}_1\sin {\mathrm{\&theta;}}_2& -\sin {\mathrm{\&theta;}}_1\cos {\mathrm{\&theta;}}_2& \cos {\mathrm{\&theta;}}_1\cos {\mathrm{\&theta;}}_2\end{array}\right),$ θ ₁And θ ₂Be respectively the anglec of rotation of setting, its span is

The symbolic vector piece x that (15) will finish after rotation modulation is processed deposits memory in.

2. method according to claim 1, it is characterized in that: described step (2) further comprises following content of operation:

(21) transmitting terminal is to all users' symbolic vector piece x, according to the centralized or distributed OFDM mode assignments OFDM running time-frequency resource of setting, wherein, time resource is the time slot that the OFDM symbol sends successively, and frequency resource is to send the shared subcarrier bandwidth of each OFDM symbol; Namely the quantity L of each included user modulation symbol is set in each OFDM symbol: In the formula, OFDM_Length is the number of modulation symbols in each OFDM symbol, and P is all users' sum, and S is the modulation symbol number that at every turn transmits transmission each user, and OFDM_Num is the OFDM symbolic number that sends in each OFDM transmission course; Thereby so that each OFDM symbol comprises L * P modulation symbol, it occupies OFDM_Length subcarrier bandwidth at frequency domain; And always total OFDM_Num OFDM symbol occupies OFDM_Num time slot in time domain;

(22) the symbolic vector piece of each user in the OFDM symbol is carried out following corresponding Q road interleaving treatment: the time-frequency of modulation symbol vector interweaves, Q road frequency-domain-interleaving and Q road time-frequency two-dimensional interleaver interweave.

3. method according to claim 2 is characterized in that: when transmitting terminal carries out the Q road when interweaving according to centralized OFDM pattern, described step (22) comprises following content of operation:

(221) symbolic vector of transmitting terminal after to the rotation modulation of same user in each OFDM symbol period carried out the time-frequency interleaving treatment, and the time-frequency interlacing rule is: the symbolic vector behind each user's the rotation modulation is stored in according to writing mode line by line Behind the interleaver of form, take out according to mode by column again, with the conversion that interweaves of the time-frequency by this symbolic vector, reduce in each rotation modulation time domain between two adjacent-symbol vectors and the correlation of frequency domain, in the formula, D is the dimension 4 of rotation modulation;

(222) the Q road quadrature component of the symbolic vector after the time-frequency of each user in each OFDM symbol period is interweaved is sequentially carried out frequency-domain-interleaving and is processed, and the frequency-domain-interleaving rule is that the modulation symbol vector of the L that belongs to same user in each OFDM symbol is processed together: first with in this L symbolic vector, be spaced apart

The Q road component of D symbolic vector be made as one group, total

Group; Again with the Q road component in every group sequentially to the right one of loopy moving, i.e. Q _fMove to

The position, and

Move to

The position,

Then move to

The position, correspondingly, last Q road component then moves to Q _fThe position; And then with the new symbolic vector of Q road quadrature component merging composition after I road in-phase component and the displacement;

(223) according to the time-frequency two-dimensional interlacing rule of setting, each user is evenly distributed in whole S modulation symbols that in each OFDM symbol, at every turn send carries out interleaving treatment, make quadrature component and its in-phase component of any one modulation symbol in each this S modulation symbol that sends of each user after interweaving uncorrelated mutually as much as possible on time and frequency, even the distance of quadrature component and its in-phase component is far away as far as possible;

When transmitting terminal carries out the Q road when interweaving according to distributed OFDM pattern, after first operation rules according to above-mentioned centralized OFDM pattern calculates step (22) result, again centralized result of calculation distributed frequency point allocation mode according to step (21) on frequency domain is come the even expansion of result, the invariant position of time domain, and, the relative position of frequency domain is also constant, has just changed the absolute position of subcarrier frequency.

4. method according to claim 3, it is characterized in that: described time-frequency two-dimensional interlacing rule is: will this same user, the modulation symbol of an interval W subcarrier bandwidth is made as one group on frequency domain, to choose two sequence numbers be f to hypothesis again ₁, f ₂Subcarrier, wherein, f ₂=f ₁+ W, W are two sub-carrier frequency point f ₁And f ₂Bandwidth granularity;

And the position coordinates of establishing the Q road component of each modulation symbol is (f, t), represent that f modulation symbol in each OFDM symbol is positioned at f sub-carrier frequency point on the frequency domain and t OFDM symbol on the time domain, natural number t is the sequence number of OFDM symbol, and its maximum is OFDM_Num; The Q road component of order choice of modulation symbol is namely chosen first f in the 1st the OFDM symbol first ₁The Q road component of individual modulation symbol is chosen at interval on the time domain again

Of individual OFDM symbol

F in the individual OFDM symbol ₂The Q road component of individual modulation symbol; Then choose f in the 2nd the OFDM symbol ₁The Q road component of individual modulation symbol is chosen at again

F in the individual OFDM symbol ₂The Q road component of individual modulation symbol continues to choose f in the 3rd the OFDM symbol ₁The Q road component of individual modulation symbol chooses again F in the individual OFDM symbol ₂The Q road component of individual modulation symbol, the like, according on time domain, from the 1st OFDM symbol choosing, select again to be separated by with the 1st OFDM symbol

Of individual OFDM symbol Individual OFDM symbol, and then select the 2nd OFDM symbol, select again to be separated by with the 2nd OFDM symbol

Of individual OFDM symbol

Individual OFDM symbol, the like, choose always

Individual OFDM symbol is selected and the again Individual OFDM symbol is separated by

(OFDM_Num) individual OFDM symbol of individual OFDM symbol on frequency domain, is exactly f ₁, f ₂Alternate selection; Like this, before interweaving, the position coordinates of the Q road component of each modulation symbol in each OFDM symbol is respectively:

$\{(f_1,1),(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+1),(f_1,2),(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+2),...,(f_1,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}),(f_2,\mathrm{OFDM}\_\mathrm{Num})\},$ After interweaving through the time-frequency two-dimensional of Q road component, the position coordinates of the frequency-domain and time-domain that it is occupied is the Q road component result of one of loopy moving to the right sequentially of original OFDM symbol just, is $\{(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+1),(f_1,2),(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+2),...,(f_1,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}),(f_2,\mathrm{OFDM}\_\mathrm{Num}),(f_1,1)\};$ Therefore, the I road component after the process time-frequency two-dimensional interweaves and the time interval minimum of Q road component are

The time length of field OFDM_Num * T that is about the OFDM symbol _sHalf, wherein, T _sIt is the transmission time of OFDM symbol; Frequency domain interval be corresponding ofdm system frequency domain length 1/2nd; Thereby can fully effectively utilize frequency diversity and the time diversity of ofdm system so that the low time-frequency two-dimensional of computation complexity interweaves, and realize combined optimization with modulation diversity.

5. method according to claim 1 is characterized in that, described step (3) further comprises following content of operation:

(31) respectively to not enough IFFT computing length in each OFDM symbol the position long zero padding after, again each OFDM symbol is carried out respectively the IFFT computing according to the following equation:

In the formula, N is sub-carrier number, and X (k) is the complex signal of setting under the modulating mode, x (n) be the OFDM symbol in the sampling of time domain, the definition of the j of imaginary unit is: j ²=-1, k is the sequence number of the symbolic vector in the OFDM symbol, and its span is the nonnegative integer of [0, N-1];

(32) the OFDM symbol after each process IFFT computing is added respectively cyclic prefix CP, eliminate the intersymbol interference that multi-path channel transmission causes; The concrete operations content is: μ symbol of each OFDM symbol afterbody copied the front end that is added into this OFDM symbol, and wherein, μ is the length of CP;

(33) send successively each OFDM symbol.

6. method according to claim 3 is characterized in that,

Described step (3) further comprises following content of operation:

(31) respectively to not enough IFFT computing length in each OFDM symbol the position long zero padding after, again each OFDM symbol is carried out respectively the IFFT computing according to the following equation:

In the formula, N is sub-carrier number, and X (k) is the complex signal of setting under the modulating mode, x (n) be the OFDM symbol in the sampling of time domain, the definition of the j of imaginary unit is: j ²=-1, k is the sequence number of the symbolic vector in the OFDM symbol, and its span is the nonnegative integer of [0, N-1];

(32) the OFDM symbol after each process IFFT computing is added respectively cyclic prefix CP, eliminate the intersymbol interference that multi-path channel transmission causes; The concrete operations content is: μ symbol of each OFDM symbol afterbody copied the front end that is added into this OFDM symbol, and wherein, μ is the length of CP;

(33) send successively each OFDM symbol;

Described step (4) further comprises following content of operation:

(41) behind the receiving terminal receive data, it is separated OFDM process: first each the OFDM symbol that receives is removed respectively CP, each the OFDM symbol that is about to receive is deleted respectively μ symbol of its head; Again each OFDM symbol is carried out respectively fast Fourier transform FFT computing according to the following equation: In the formula, N is sub-carrier number, and X (k) is the complex signal of setting under the modulating mode, x (n) be the OFDM symbol in the sampling of time domain, the definition of the j of imaginary unit is: j ²=-1, k is the sequence number of the symbolic vector in the OFDM symbol, and its span is the nonnegative integer of [0, N-1]; Then, the OFDM symbol after the conversion is stored;

(42) the OFDM symbol after the conversion is carried out phase compensation, in order to eliminate Multipath Transmission to the impact of data according to channel estimation value; The phase compensation formula is:

In the formula, x (t) is the symbolic vector in each OFDM symbol, h (t),

With | h (t) | be respectively channel guess value, the conjugation of channel guess value and mould;

(43) each the OFDM symbol after the phase compensation is removed zero, namely delete step (31) then, is stored each OFDM symbol for long add zero in position of coupling IFFT computing length;

(44) the centralized or distributed OFDM pattern of selecting according to four-dimensional rotation modulation and step (21) is carried out the deinterleaving of corresponding Q road to the symbolic vector in each OFDM symbol and is processed, and namely carries out reverse process according to the rule of correspondence of step (22).

(45) proceed OFDM and separate the time-frequency resource allocating operation: with this step (21) be distributed in whole OFDM symbols on the OFDM running time-frequency resource all L * P modulation symbol according to the contrary operation of this step sequentially, again be reduced to all users' of serial symbolic vector;

(46) adopt the maximum-likelihood demodulation mode that the symbolic vector that OFDM separates after the time-frequency resource allocating is rotated demodulation: take through the rotation planisphere after the multipath channel as demodulation reference constellation figure, the Euclidean distance of each constellation point among each symbolic vector in the symbolic vector set that calculating receives and its reference constellation figure, obtain respectively shining upon the log-likelihood ratio of each bit that becomes each symbolic vector, be used for decoding;

(47) according to the corresponding decoded mode of coding mode selection, every group of OFDM symbol substitution is reduced to K the information bit that the position is long, all flow process finishes.

7. method according to claim 6 is characterized in that:

Described step (44) comprises following content of operation:

(441) according to the reverse process method of the time-frequency two-dimensional interlacing rule of step (223) the Q road component of symbolic vector is carried out deinterleaving: the first Q road component of order choice of modulation symbol, namely choose first the

F in the individual OFDM symbol ₂The Q road component of individual modulation symbol is chosen f in the 2nd the OFDM symbol again ₁The Q road component of individual modulation symbol then chooses

F in the individual OFDM symbol ₂The Q road component of individual modulation symbol is chosen f in the 3rd the OFDM symbol again ₁The Q road component of individual modulation symbol continues to choose

F in the individual OFDM symbol ₂Then the Q road component of individual modulation symbol chooses f in the 3rd the OFDM symbol ₁The Q road component of individual modulation symbol, the like; On time domain according to from

Individual OFDM symbol selects, and selects the 2nd OFDM symbol again, then selects to be separated by with it

Of individual OFDM symbol

Individual OFDM symbol is selected from the 3rd OFDM symbol of 1 OFDM symbol of the 2nd increase again, then selects to be separated by with it

Of individual OFDM symbol

Individual OFDM symbol, the like, choose Individual OFDM symbol is selected to be separated by with it again

(OFDM_Num) individual OFDM symbol of individual OFDM symbol is chosen the 1st OFDM symbol at last; F at frequency domain ₂, f ₁Alternate selection; Like this, before interweaving, the position coordinates of the Q road component of each modulation symbol in each OFDM symbol is respectively:

$\{(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+1),(f_1,2),(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+2),...,(f_1,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}),(f_2,\mathrm{OFDM}\_\mathrm{Num}),(f_1,1)\},$

After the time-frequency two-dimensional deinterleaving through Q road component, the position coordinates of the frequency-domain and time-domain that it is occupied is the Q road component result of one of loopy moving left sequentially of original OFDM symbol just, is:

$\{(f_1,1),(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+1),(f_1,2),(f_2,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}+2),...,(f_1,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}),(f_2,\mathrm{OFDM}\_\mathrm{Num})\},$ So that Q road quadrature component symbol all carries out place-exchange according to above-mentioned rule on time and frequency: $(f_1,1)\&RightArrow;(f_2,\mathrm{OFDM}\_\mathrm{Num}),(f_2,\mathrm{OFDM}\_\mathrm{Num})\&RightArrow;(f_1,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}),$ $(f_1,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2})\&RightArrow;(f_2,\mathrm{OFDM}\_\mathrm{Num}-1),(f_2,\mathrm{OFDM}\_\mathrm{Num}-1)\&RightArrow;(f_1,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}-1),$ $(f_1,\frac{\mathrm{OFDM}\_\mathrm{Num}}{2}-1)\&RightArrow;(f_2,\mathrm{OFDM}\_\mathrm{Num}-2),......,(f_2,\mathrm{OFDM}\_\mathrm{Num}/2+2)\&RightArrow;(f_1,2),$ (f ₁,2)→(f ₂,OFDM_Num/2+1)，(f ₂,OFDM_Num/2+1)→(f ₁,1)；

(442) according to the reverse process method of step (222) the Q road component of symbolic vector is separated frequency-domain-interleaving, its rule is: in same user's L the symbolic vector, be spaced apart in each OFDM symbol

The Q road component of D symbolic vector be made as one group, with the Q road component in this group successively one of loopy moving left, imaginary part and the real part that then will originally belong to the prosign vector mate reduction;

(443) according to the reverse process method of step (221) symbolic vector is carried out the time-frequency deinterleaving, its rule is: to each user's symbolic vector according to writing mode by column be stored in

Behind the interleaver of form, take out according to row-by-row system again, finish the time-frequency deinterleaving conversion of symbolic vector;

When receiving terminal carries out the deinterleaving of Q road according to distributed OFDM pattern, then first according to centralized frequency point allocation mode with distributed reduction become centralized after, carry out again above-mentioned steps (44) corresponding operating.

8. according to claim 6 or 7 described methods, it is characterized in that: in the planisphere of described step (46), every kind of combinatorial mapping of a plurality of bits becomes the corresponding symbol of certain point in the rotation planisphere, be 0 or 1 according to i position bit in these bit combinations, planisphere is divided into two set: the set of 0 constellation point and 1 constellation point are gathered; At this moment, judge that the computing formula that i position bit in the corresponding a plurality of bits of each symbol is respectively 0 and 1 probability is respectively: With

In the formula, { d _I0For this symbol that receives be the distance set of 0 all constellation point of dividing according to i position bit, { d _I1For this symbol that receives be the distance set of 1 all constellation point of dividing according to i position bit, natural number i is bit sequence in the bit combination; Calculate respectively thus the log-likelihood ratio of corresponding each bit of each symbol:

In the formula, b _vBy v bit in certain symbol of a plurality of bit mappings one-tenth after the modulation; P (b _v=0|r) be the symbol that receives when being r, judge bit b _vBe 0 probability, P (b _v=1|r) be the symbol that receives when being r, judge bit b _vIt is 1 probability.

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