阅读说明：本技术 两时域分量等功率加权变换实现信号时频域能量平均化的方法 (Method for realizing signal time-frequency domain energy averaging by two time-domain component equipower weighting transformation ) 是由 房宵杰 李成方 李勇 沙学军 梅林� 李卓明 于 2019-06-26 设计创作，主要内容包括：基于两时域分量等功率加权变换的时频域能量平均化信号传输方法,涉及无线通信领域是为了提高传输性能。本发明提出了对频域信号做两时分量变换不断迭代,实现信号的频域分集,利用迭代算法使时频域符号能量均匀化,其运算复杂度低,能够将其应用到单载波和OFDM系统中。改变变换过程中的加权系数也可以用来提升信息的安全性。实现一种时频域能量均匀分布的信号,使其在时选、频选以及双选信道下均有很好的误比特率。(A time-frequency domain energy averaging signal transmission method based on two time-domain components equal-power weighted transformation relates to the field of wireless communication and aims to improve transmission performance. The invention provides the method for continuously iterating the frequency domain signal by carrying out two-time component transformation, realizes the frequency domain diversity of the signal, homogenizes the symbol energy of the time domain and the frequency domain by utilizing an iterative algorithm, has low operation complexity and can be applied to a single carrier system and an OFDM system. Changing the weighting coefficients in the transformation process can also be used to improve the security of the information. The signal with uniformly distributed time-frequency domain energy is realized, and the signal has good bit error rate under time selection, frequency selection and double-selection channels.)

1. The time-frequency domain energy averaging signal transmission method based on two time-domain components equal-power weighted transformation is characterized in that: the time-frequency domain energy averaging signal transmission method based on two time-domain components equal power weighted transformation under a frequency domain diversity time diversity OFDM system comprises the following steps:

the signal transmitting method comprises the following steps:

step one, performing baseband modulation on an original baseband symbol to obtain a modulation signal;

step two, performing serial-to-parallel conversion on the modulation signal obtained in the step one; obtaining a parallel signal;

step three, performing equal-power two-time domain component weighting transformation iterative operation on the parallel converted signal obtained in the step one to obtain an iterative operation signal;

step four, performing N-point IFFT on the signals obtained in the step three after the iterative operation to obtain N-point IFFT converted signals;

step five, performing parallel-serial conversion on the signals obtained in the step three after the N-point IFFT conversion; obtaining a serial signal;

step six, performing CP adding operation on the serial signals obtained in the step five to obtain signals added with CP;

step seven, carrying out time slot expansion on the signal added with the CP obtained in the step six to obtain a signal after time slot expansion operation;

step eight, the signals obtained in the step seven after the time slot expansion operation are subjected to digital/analog conversion and up-conversion processing and then are sent to a channel through an antenna;

the signal receiving method comprises the following steps:

step nine, carrying out down-conversion processing and analog/digital conversion on the received radio frequency signal to obtain a digital baseband signal;

step ten, extracting corresponding time slots from the digital baseband signals obtained in the step nine through two-time component inverse transformation to obtain different time slot channel gains; removing the CP to obtain a signal after the CP is removed;

step eleven, performing MMSE time domain equalization operation on the signal obtained in the step eleven after the CP is removed to obtain a signal after the MMSE time domain equalization operation

Step twelve, performing serial-to-parallel conversion on the signals obtained in the step eleven after the CPMMSE time domain equalization operation is removed to obtain parallel signals;

thirteen, performing FFT processing on the parallel signals obtained in the eleventh step to obtain frequency domain signals;

and step fourteen, performing equal-power two-time-domain component weighted transformation quasi-iteration on the frequency domain signal obtained in the step thirteen, recovering an original baseband symbol, and completing one time of time-frequency domain energy-averaged signal transmission based on the equal-power two-time-domain component weighted transformation.

2. The time-frequency domain energy averaging signal transmission method based on two time-domain components equal-power weighted transformation is characterized in that: the time-frequency domain energy averaging signal transmission method based on two time-domain components equal-power weighted transformation under a single carrier system with time-domain energy uniformization and time diversity is as follows:

the signal transmitting method comprises the following steps:

step one, performing baseband modulation on an original baseband symbol to obtain a modulation signal;

step two, carrying out equal-power two-time domain component weighting transformation iterative operation on the modulation signal obtained in the step one to obtain a signal after the iterative operation;

step three, carrying out equal-power two-time domain component weighting transformation iterative operation on the parallel converted signal obtained in the step one, obtaining digital/analog conversion and up-conversion processing, and then sending the processed signal to a channel through an antenna;

step four, carrying out time slot expansion on the signal obtained in the step three after the iterative operation to obtain a signal after the time slot expansion operation;

step five, the signals after the time slot expansion operation obtained in the step four are subjected to digital/analog conversion and up-conversion processing and then are sent to a channel through an antenna;

the signal receiving method comprises the following steps:

step six, performing down-conversion processing and analog/digital conversion on the received radio frequency signal to obtain a digital baseband signal;

step seven, MMSE time domain equalization operation is carried out on the digital baseband signals obtained in the step six, and signals after MMSE time domain equalization operation are obtained;

step eight, carrying out time slot extraction operation on the signals obtained in the step seven after MMSE time domain equalization operation to obtain signals after time slot extraction;

step nine, performing two-time component weighting transformation inverse iteration operation on the signal obtained after the time slot extraction in the step eight to obtain a signal after the inverse iteration operation;

and step ten, performing baseband demodulation on the signal obtained in the step nine after the inverse iteration operation to recover an original baseband symbol, and completing one time of time-frequency domain energy-averaged signal transmission based on two time-domain components and equal power weighted transformation.

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to a method for realizing time-frequency domain energy averaging of signals by using an equal-power weighted transformation iteration method of two time-domain components.

Background

Under the frequency selective channel, the traditional single carrier signal has better performance because the energy of the frequency domain is uniformly distributed. Under the time-selective channel, the traditional multi-carrier has better performance because the energy distribution in the time domain is uniform. The classical mixed carrier system is realized based on a four-term weighted fractional Fourier transform theory. The method can realize that the signal time domain energy (the sum of the time domain and the time domain turnover component) is equal to the signal frequency domain energy (the sum of the frequency domain and the frequency domain turnover component), and the signal energy distribution has better error rate performance under the double-selection channel. In order to make the four energies of the time-frequency domain of the signal equal, the clever proposes: the publication number is: CN108833326A, "transmission method of multi-component power-averaged generalized mixed carrier". On the basis, in order to adapt to different channels, the clever proposes the disclosure numbers as follows: CN: 108924077A, the transmission method under the time selective fading channel of the generalized mixed carrier system () and the publication number are: CN: 108737317A entitled generalized Mixed Carrier frequency-Selective channel Transmission method.

The classical four-weighted fractional fourier transform can be represented as follows:

by relaxing the constraint condition of the classical four-item weighted fractional Fourier transform, the transformation reversibility and the energy invariance are only satisfied, and the two-time-domain component equipower weighted transformation is proposed by clever, and the definition form is as follows:

the positive and inverse transformation weighting coefficients are respectively calculated by the following formulas:

[z₀ z₁ z₂ z₃]intermediate variables are:

θ_isatisfies the following conditions:or

It can be seen from the formula that the two time domain components are subjected to equal power weighted transformation, the time domain signal components and the time domain inversion components are subjected to weighted summation, and the squares of the weighted coefficients are allThe original time domain signal component and the time domain inversion component have equal power, the frequency domain component power is 0, because only the time domain component signal is transmitted, the signal energy is uniformly distributed in the frequency domain, the loss of the symbol energy caused by the deep fading of one frequency point of the frequency domain is averagely distributed to each time domain information source symbol, the average signal-to-noise ratio of each symbol of the time domain is higher, and therefore better performance can be obtained under a frequency selection channel. Similarly, for equal power transformation of two frequency domain components, the energy of the time domain component is set to zero, and both the frequency domain component and the frequency domain inversion component are set to zeroWhen only the overloaded signal is transmittedThe wave component signals and the signal energy are uniformly distributed in the time domain, and the energy of deep fading loss of the time domain can be evenly distributed to each frequency domain source symbol, so that the performance is better under a time-selective channel.

The two time domain component transformations introduce self inverse signals to carry out equal power weighted superposition, when the time domain has a little fading, the symbol energy of the time domain component and the time domain turnover component at the same position is lost, although the symbol energy is at the same position, the symbol energy corresponds to two different symbols, and after the inverse transformation, the fading symbol can obtain half of the energy compensation, so that the performance of the signal for selecting channels when resisting the time is improved. And arranging the symbols of the second half length after the conversion in a reverse order to ensure that the symbols with the same length are all spaced equally on the time domain except for the fixed point. All the two time domain components mentioned below are subjected to such post-processing after being subjected to equal power conversion. For simplicity, the two-time component weighted transform is abbreviated below.

The time diversity principle achieved by the two time domain component weighted transform is shown in fig. 1.

To accommodate different channels, many mixed carrier schemes have been proposed. The fractional Fourier transform mixed multi-carrier system based on the four-item weighting can simultaneously transmit time domain components and frequency domain components to resist against double-channel selection, and can match different channels by adjusting the distribution of signal time domain and frequency domain component energy to improve the system performance and realize the conversion of single carrier and multi-carrier transmission. From the above analysis, it can be known that the time domain energy averaging can effectively combat the time-selective channel, and the frequency domain energy averaging can effectively combat the frequency-selective channel, however, it can be observed that no matter how the power ratio of the time domain component and the frequency domain component is designed, it is impossible to simultaneously achieve the high time domain and frequency domain energy averaging in the existing mixed carrier system.

If a signal has the property of uniform distribution in the time-frequency domain, the signal is subjected to frequency selection, time selection and double selection channels, the energy loss of each symbol is the minimum, and the energy loss caused by fading of the time-frequency domain channel is uniformly distributed on each symbol.

Disclosure of Invention

The invention provides a time-frequency domain energy averaging signal transmission method based on two time-domain components equal-power weighted transformation, aiming at realizing a signal with uniformly distributed time-frequency domain energy and ensuring that the signal has good bit error rate performance under time selection, frequency selection and double-selection channels.

The time-frequency domain energy averaging signal transmission method based on the equal power weighted transformation of two time domain components is a time-frequency domain energy averaging signal transmission method based on the equal power weighted transformation of two time domain components under a frequency domain diversity time diversity OFDM system:

the signal transmitting method comprises the following steps:

step one, performing baseband modulation on an original baseband symbol to obtain a modulation signal;

step two, performing serial-to-parallel conversion on the modulation signal obtained in the step one; obtaining a parallel signal;

step three, performing equal-power two-time domain component weighting transformation iterative operation on the parallel converted signal obtained in the step one to obtain an iterative operation signal;

step four, performing N-point IFFT on the signals obtained in the step three after the iterative operation to obtain N-point IFFT converted signals;

step five, performing parallel-serial conversion on the signals obtained in the step four after the N-point IFFT conversion; obtaining a serial signal;

step six, performing CP adding operation on the serial signals obtained in the step five to obtain signals added with CP;

step seven, carrying out time slot expansion on the signal added with the CP obtained in the step six to obtain a signal after time slot expansion operation;

step eight, the signals obtained in the step seven after the time slot expansion operation are subjected to digital/analog conversion and up-conversion processing and then are sent to a channel through an antenna;

the signal receiving method comprises the following steps:

step nine, carrying out down-conversion processing and analog/digital conversion on the received radio frequency signal to obtain a digital baseband signal;

step ten, extracting corresponding time slots from the digital baseband signals obtained in the step nine through two-time component inverse transformation to obtain different time slot channel gains; removing the CP to obtain a signal after the CP is removed;

step eleven, performing MMSE time domain equalization operation on the signal obtained in the step eleven after the CP is removed to obtain a signal after the MMSE time domain equalization operation

Step twelve, performing serial-to-parallel conversion on the signals obtained in the step eleven after the CPMMSE time domain equalization operation is removed to obtain parallel signals;

thirteen, performing FFT processing on the parallel signals obtained in the step twelve to obtain frequency domain signals;

and step fourteen, performing equal-power two-time-domain component weighted transformation quasi-iteration on the frequency domain signal obtained in the step thirteen, recovering an original baseband symbol, and completing one time of time-frequency domain energy-averaged signal transmission based on the equal-power two-time-domain component weighted transformation.

The time-frequency domain energy averaging signal transmission method based on the two-time domain component equipower weighted transformation is a time-frequency domain energy averaging signal transmission method based on the two-time domain component equipower weighted transformation under a single carrier system with time-domain energy averaging time diversity:

the signal transmitting method comprises the following steps:

step one, performing baseband modulation on an original baseband symbol to obtain a modulation signal;

step two, carrying out equal-power two-time domain component weighting transformation iterative operation on the modulation signal obtained in the step one to obtain a signal after the iterative operation;

step three, carrying out equal-power two-time domain component weighting transformation iterative operation on the parallel converted signal obtained in the step one to obtain digital/analog conversion and up-conversion processing, and then sending the processed signal to a channel through an antenna;

step four, carrying out time slot expansion on the signal obtained in the step three after the iterative operation to obtain a signal after the time slot expansion operation;

step five, the signals after the time slot expansion operation obtained in the step four are subjected to digital/analog conversion and up-conversion processing and then are sent to a channel through an antenna;

the signal receiving method comprises the following steps:

step six, performing down-conversion processing and analog/digital conversion on the received radio frequency signal to obtain a digital baseband signal;

step seven, performing MMSE time domain equalization operation on the digital baseband signal obtained in the step six to obtain a signal after the MMSE time domain equalization operation;

step eight, carrying out time slot extraction operation on the signals obtained in the step seven after MMSE time domain equalization operation to obtain signals after time slot extraction;

step nine, performing two-time component weighting transformation inverse iteration operation on the signal obtained after the time slot extraction in the step eight to obtain a signal after the inverse iteration operation;

and step ten, performing baseband demodulation on the signal obtained in the step nine after the inverse iteration operation to recover an original baseband symbol, and completing one time of time-frequency domain energy-averaged signal transmission based on two time-domain components and equal power weighted transformation.

The invention has the following beneficial effects: the invention provides a method for continuously iterating frequency domain signals by carrying out two-time component transformation, realizing frequency domain diversity of the signals, homogenizing time-frequency domain symbol energy by utilizing an iterative algorithm, and provides an effective iterative algorithm, wherein the operation complexity is O (Nlog)₂(N)), it is applied to single carrier and OFDM systems. The method is applied to the traditional single carrier, effectively improves the time domain deep fading resistance of the traditional single carrier, effectively improves the frequency domain deep fading resistance of the traditional single carrier when applied to the multi-carrier, and improves the transmission performance of the traditional single carrier and the multi-carrier under the double-selection channel. In essence, the transform iteration technology can be regarded as a coding technology for a source, the coding rate is not changed, excessive complexity is not increased, and effective performance improvement is realized. The scheme has wide application range, and is not only suitable for a single carrier system, but also suitable for a multi-carrier system and a mixed carrier system. In addition, the coefficient in the iterative process can be adjusted at will, so that the safety of the information can be improved.

Drawings

FIG. 1 is a schematic diagram illustrating the time diversity implementation principle of two time domain component weighting transformation according to the background art of the present invention;

FIG. 2 is a schematic diagram of a signal transmission principle of a time-frequency domain energy-averaged signal transmission method based on two time-domain components equal-power weighted transformation in a frequency domain diversity time diversity OFDM system according to the present invention;

FIG. 3 is a schematic diagram of a signal transmission principle of a time-frequency domain energy-averaging signal transmission method based on two time-domain components equal-power weighted transformation in a single carrier system with time-domain energy uniformization and time diversity according to the present invention;

FIG. 4 is a schematic diagram of an iteration flow at a transmitting end of an original symbol;

wherein: block_k，iAn ith iteration module of a kth stage of a sending end;

FIG. 5 is a transmitting end Block_k，iProcessing flow of the module;

wherein: n is the number of subcarriers, k is 1, 2₂(N)， Represents Block_k，iThe input of the first level is an original signal;represents Block_k，iTo output of (c). W_0，k，W_1，kFor weighting coefficients, different blocks_k，iDifferent weighting coefficients may be employed; the purpose of the half-symbol block inversion is to achieve an averaging of the symbol energy allocation distances.

FIG. 6 is a schematic diagram of an iterative flow of inverse transform at the receiving end of the present invention;

wherein: block _ inv_k，iA kth level ith path iteration module of a receiving end;

k＝1，2，...，log₂(N)，i＝1，2，...，2^K-1，[w_0，k]^-1、[w_1，k]^-1represents the inverse transform coefficients; input/output and Block_k，iThe modules are opposite;

fig. 7 is a schematic diagram of the distribution change of the signal information after two-stage iteration (taking the length of the input signal as 8 as an example).

FIG. 8 is a schematic diagram showing simulation of BER performance of signals in a pure frequency selective channel (channel 1); (the original signal length is set as 128 points in the following simulation result graphs).

It is composed of

FIG. 9 is a schematic diagram of simulation of BER performance of signals under a single time-selective channel (channel 2);

FIG. 10 is a diagram showing simulation of BER performance of signals under a double channel selection;

fig. 11 is a schematic diagram illustrating the influence of the number of iterations of the OFDM system under channel 4 on the performance; (taking 128 carrier frequencies as an example);

FIG. 12 is a schematic diagram of performance simulation under frequency selective channel for 4 and 6 iterations of single carrier and OFDM;

fig. 13 is a schematic diagram of performance simulation under a time-selective channel for 4 and 6 iterations of single carrier and OFDM;

FIG. 14 is a diagram of performance simulation under dual channel selection for 4 and 6 iterations of single carrier and OFDM;

Detailed Description