阅读说明：本技术 一种分集拷贝接收性能优化方法 (Diversity copy receiving performance optimization method ) 是由 楼红伟 刘琳童 黄梅莹 李正卫 郭昌松 于 2019-10-21 设计创作，主要内容包括：本发明提供的一种分集拷贝接收性能优化方法,是利用最大信噪比合并均衡方式而做出的特殊方法：对I路和Q路的信道矢量重新进行整合,组成新的信道矩阵,组合I路和Q路的接收信号,这些信号对应的原始比特信息是同一个,通过变形的最大信噪比合并均衡矩阵,可基于比特级的最大信噪比进行接收。(The invention provides a diversity copy receiving performance optimization method, which is a special method made by utilizing a maximum signal-to-noise ratio combining and balancing mode, and comprises the following steps of: the channel vectors of the path I and the path Q are integrated again to form a new channel matrix, the receiving signals of the path I and the path Q are combined, the original bit information corresponding to the signals is the same, and the signals can be received based on the maximum signal-to-noise ratio of the bit level by combining the equalization matrix through the deformed maximum signal-to-noise ratio.)

1. A method for optimizing the performance of diversity copy reception, comprising the steps of:

first, according to the preamble information in the communication system, we can obtain the channel estimation of all the subcarriers carrying useful information for transmission:

h(k) k∈(0,N-1) (1)

n is the number of useful subcarriers;

secondly, according to the mapping rule of diversity copying of the current control frame, the frequency domain data of each OFDM symbol is a complex value consisting of an I path and a Q path, wherein the I path corresponds to the real part of the complex value, and the Q path corresponds to the imaginary part of the complex value;

for originally transmitted bit information stream s e(s)₀,…,s₂₅₅) After FFT at receiving end, copy information combination is carried out, firstly, I-path multiple received data r on different subcarriers in all OFDM symbols corresponding to current bit s are found out_I(i) Composition ofVector r_I(ii) a And simultaneously estimating the subcarrier channels corresponding to each path I_I(i) H (i) a composition vector h_I(ii) a The I path refers to the real part of the corresponding complex value, and the Q path refers to the imaginary part of the complex value;

thirdly, finding out Q paths of multiple received data r on different subcarriers in all OFDM symbols corresponding to the bit s_Q(q) composition vector r_Q(ii) a And simultaneously estimating the sub-carrier wave channels corresponding to each Q path_Q(q) h (q) a composition vector h_Q；

Fourthly, obtaining the combined output result of the optimal signal-to-noise ratio, namely the soft information input required by the decoder;

and step five, entering a process of processing the next bit information s, returning to the first step to the fourth step, processing the next bit information s in the same way, processing and mapping the next bit information s to subcarriers on a frequency domain one by one, and obtaining all the residual maximum signal-to-noise ratio combined values.

Technical Field

The invention relates to a communication technology in a power information acquisition system, in particular to a receiving performance optimization method under special bit level diversity copying in frame control of a high-speed carrier communication system in the power information acquisition system.

Background

Generally, in an OFDM communication system, one or more bit stream information is mapped to a certain subcarrier under different channels after constellation point mapping, that is, the constellation point modulation information of all the diversity is the same. However, in the power line communication system, the diversity transmission processing of the control frame is more specific, and the modulation information of the constellation point in each diversity is different, and the modulation information respectively takes the path I and the path Q as the processing unit; for each OFDM symbol m of the control frame, the available subcarriers for I way: an input bit stream (for example, 256 bits) is copied to corresponding carriers according to a specific Offset1[ m ] in sequence until the copying of the available carriers is completed, that is, the bits sequentially filled on the effective subcarriers are numbered (c + Offset1[ m ]) mod256, and the value of c is from 0 to 255 in sequence; for the Q-path, the input bit stream (256 bits) is copied to the corresponding carrier plus a specific Offset2[ m ] until the copying of the available carrier is completed, i.e. the bits with the bit number (c + Offset2[ m ]) mod256 are sequentially filled on the active sub-carriers, and the value of c is sequentially from 0 to 255. That is, if the number of available subcarriers is 411 when the communication band is set to 0, the same 256 bits of information are not only cyclically and repeatedly copied on the I channel but also only a part of the bits of information are repeatedly copied. The same is true for the Q path, and the duplicated bit information is different from that for the I path because the starting number of the duplicated bit stream is different. If the communication frequency band is set to 1, 2 and 3, only part of bit information in the I path or the Q path of a symbol can be copied because the number of available subcarriers is much less than 256, and only a complete 256-bit information copy can be completed by a plurality of symbols.

The diversity is to transmit the transmitted bit information on different subcarriers, and the number of the subcarriers can be configured with different values according to the needs; the constellation point mapping is a value of a complex number field formed by a plurality of bit numbers, is used for modulating a certain subcarrier on an OFDM symbol and is equivalent to amplitude and phase information of the subcarrier.

Therefore, in a general hierarchical copy receiving method, soft information after constellation demodulation is output is combined, for example, in QPSK, complex numbers on available subcarriers in all frequency domains are subjected to constellation demodulation, soft information of an I path and a Q path is output, and then demapping is performed according to a mapping rule, and soft information corresponding to the same bit is respectively combined.

Disclosure of Invention

In order to solve the technical problem, the invention provides a diversity copy receiving performance optimization method.

The invention discloses a diversity copy receiving performance optimization method, which comprises the following steps:

first, according to the preamble information in the communication system, we can obtain the channel estimation of all the subcarriers carrying useful information for transmission:

h(k) k∈(0,N-1) (1)

n is the number of useful subcarriers;

secondly, according to the mapping rule of diversity copying of the current control frame, the frequency domain data of each OFDM symbol is a complex value consisting of an I path and a Q path, wherein the I path corresponds to the real part of the complex value, and the Q path corresponds to the imaginary part of the complex value;

for originally transmitted bit information stream s e(s)₀,…,s₂₅₅) After FFT at receiving end, copy information combination is carried out, firstly, I-path multiple received data r on different subcarriers in all OFDM symbols corresponding to current bit s are found out_I(i) Form a vector r_I(ii) a And simultaneously estimating the subcarrier channels corresponding to each path I_I(i) H (i) a composition vector h_I(ii) a The I path refers to the real part of the corresponding complex value, and the Q path refers to the imaginary part of the complex value;

third, find out all O corresponding to the bit sQ paths of multiple received data r on different subcarriers in FDM symbol_Q(q) composition vector r_Q(ii) a And simultaneously estimating the sub-carrier wave channels corresponding to each Q path_Q(q) h (q) a composition vector h_Q；

Fourthly, obtaining the combined output result of the optimal signal-to-noise ratio, namely the soft information input required by the decoder;

is the conjugate value of the corresponding channel estimation on the path I;is the conjugate of the corresponding channel estimate on the Q-path;

and step five, entering a processing process of next bit information s, returning to the first step to the fourth step, processing in the same way, processing and mapping the processed information to subcarriers on a frequency domain one by one to obtain all the residual maximum signal-to-noise ratio combined values.

The invention provides a diversity copy receiving performance optimization method, which is a special method made by using a maximum signal-to-noise ratio combination balancing mode as much as possible: the channel vectors of the path I and the path Q are integrated again to form a new channel matrix, the receiving signals of the path I and the path Q are combined, the original bit information corresponding to the signals is the same, and the signals can be received based on the maximum signal-to-noise ratio of the bit level by combining the equalization matrix through the deformed maximum signal-to-noise ratio.

Drawings

Fig. 1 is a process flow diagram of a diversity copy reception performance optimization method according to the present invention.

Detailed Description

The invention provides a diversity copy receiving performance optimization method, which comprises the following steps:

first, according to the preamble information in the communication system, we can obtain the channel estimation of all the subcarriers carrying useful information for transmission:

h(k) k∈(0,N-1) (1)

n is the number of useful subcarriers;

the simplest available received signal for channel estimation is obtained by dividing the known transmitted signal in advance and can be optimized continuously;

secondly, according to the mapping rule of the diversity copy of the current control frame, the following table is used:

that is, each subcarrier transmits two bits of information, and if the subcarrier has redundant, the original bit information is repeatedly sent; the frequency domain data of each OFDM symbol is a complex value consisting of an I path and a Q path, wherein the I path corresponds to the real part of the complex value, and the Q path corresponds to the imaginary part of the complex value; for example, each subcarrier of the frequency domain data may generate a complex value according to the table above: 1+ j, or 1-j, or-1 + j, or-1-j;

the control frame is used for providing information such as an identifier, a frame length, a diversity copy mode and the like of the current frame; in the embodiment of the invention, the control frame comprises 256 bits which are respectively projected to an I path or a Q path according to a mapping rule;

for originally transmitted bit information stream s e(s)₀,…,s₂₅₅) After FFT at receiving end, copy information combination is carried out, firstly, I-path multiple received data r on different subcarriers in all OFDM symbols corresponding to current bit s are found out_I(i) Form a vector r_I(ii) a And simultaneously estimating the subcarrier channels corresponding to each path I_I(i) H (i) a composition vector h_I(ii) a The I path refers to the real part of the corresponding complex value, and the Q path refers to the imaginary part of the complex value; the bit stream refers to a digitized bit value, 0 or 1, the bit stream is a series of 0 or 1 values, in this embodiment, 256 bits are processed one by one and mapped to the subcarriers in the frequency domainIn the wave;

thirdly, finding out Q paths of multiple received data r on different subcarriers in all OFDM symbols corresponding to the bit s_Q(q) composition vector r_Q(ii) a And simultaneously estimating the sub-carrier wave channels corresponding to each Q path_Q(q) h (q) a composition vector h_Q；

Fourthly, obtaining the combined output result of the optimal signal-to-noise ratio, namely the soft information input required by the decoder;

is the conjugate value of the corresponding channel estimation on the path I;is the conjugate of the corresponding channel estimate on the Q-path;

and step five, entering a processing process of next bit information s, returning to the first step to the fourth step, processing in the same way, processing and mapping the processed information to subcarriers on a frequency domain one by one to obtain all the residual maximum signal-to-noise ratio combined values.

The technical scheme of the invention is as follows:

for the OFDM carrier system of power line transmission, the noise floor is usually stable, and the noise of each diversity has the same characteristics, so the MRC maximum snr combining method is generally adopted, and generally the MRC combining use occasion is the combining of subcarrier level, but as mentioned above, it cannot be realized. In order to realize the combination of the maximum signal-to-noise ratio, each subcarrier is divided into bit-level information, and the real part or the imaginary part of the same information is combined, so that the combination of the maximum signal-to-noise ratio is realized, and the receiving of the optimal signal-to-noise ratio can be realized theoretically. The noise floor is the noise which cannot be avoided in the receiver, such as thermal noise, phase noise, noise caused by frequency offset, and the like. Each diversity carries the same transmitted bit information.

Receiving a signal vector: r is_Nt×1＝h_Nt×1·s+n_Nt×1(3)

h_Nt×1Is a channel coefficient matrix (degraded into column vectors when transmitting 1 more), Nt is diversity copy number, and Nt × 1 is that a signal is transmitted through Nt subcarriers respectively; s is a transmission signal; assuming that the power is unity, i.e.

E|s|²＝1 (4)

n_Nt×1For each diversity received noise, the mean is 0, the autocorrelation matrix

E(nn^H)＝σ²I_Nt×Nt(5)

nn^HRefers to the correlation matrix of the noise; means the variance of the noise, equivalent to the power of the noise; i is_Nt×NtRefers to a unit diagonal matrix;

the purpose of the maximum SNR combining MRC (maximum Ratio combining) combining algorithm is to find the optimal combining coefficient vector w_optRecording the combined signal 1 when the signal-to-noise ratio of the combined output reaches the maximum; note that combining signal 1 means: the first optimal combination is that the frequency domain receiving value of each diversity corresponding to the first information bit transmission is multiplied by the estimated value of the channel where the respective subcarrier is located, and then the sum is accumulated; at the optimal merging coefficient vector w_optIn the case of (1), the signal-to-noise ratio of the combined output is the maximum, which means that the next combined signal performs the same diversity combining processing on the other information bits, that is, the combining rules used by each information bit are the same: multiplying the frequency domain receiving value of each diversity by the estimated value of the channel in which the subcarrier is positioned, and then accumulating to obtain the maximum signal-to-noise ratio combination;

is an estimated value of an original transmission signal, w is a weight vector obtained according to a channel estimated value, w^HIs the conjugate transpose of w; r is a receive vector consisting of diversity reception; h is eachThe channel estimation value where the diversity component is located, s, refers to the original signal of transmission; n refers to the noise vector, each diversity has its own noise;

then the output signal-to-noise ratio

||·||²Expressing the European norm of a complex vector, using the Cauchy inequality

|w^Hh|²≤||w||²||h||²(8)

To obtain

The condition that the equal sign is established is

w＝c·h (10)

c is an arbitrary non-0 constant, that is, if the vector w of merging coefficients is taken_optEqual to the channel coefficient matrix (vector) h, we can obtain the maximum combined output signal-to-noise ratio

p is an index of diversity, from 1 to the maximum diversity number Nt;

it can be seen from the foregoing derivation process that, when the maximal ratio combining algorithm is adopted, the signal-to-noise ratio of the combined output is exactly equal to the sum of the signal-to-noise ratios (linear values) of the receiving antennas before combining, that is, under gaussian white noise, the diversity times are doubled (the most essential objective of diversity is to suppress noise by combining for many times, improve the strength of useful signals, further improve the signal-to-noise ratio, and improve the receiving performance), and the corresponding receiving performance can be improved by 3 dB.

In practical implementation, we can only do maximum snr combining according to the result of channel estimation, i.e. optimal combining coefficient vector w_optIs by channel estimation

To approximate. Under the condition of non-ideal channel estimation, the maximization of the signal-to-noise ratio of the combined output has only theoretical significance.

The above theoretical analysis is usually applied to diversity combining at the subcarrier level, and cannot be simply applied to bit level diversity copy combining of frame control. The diversity combining at the subcarrier level is equivalent to that the amplitude and phase information of the subcarriers received on the current frequency domain are integrated, namely complex values participate in complex value weighting combining on other subcarriers. The bit level diversity copying and combining of the frame control is that the amplitude and phase of the sub-carrier on the frequency domain of the frame control can be decomposed into a real part and an imaginary part, namely an I path and a Q path, which respectively correspond to one bit information, and in the technical scheme, the amplitude and the phase can be respectively combined with the I path or the Q path of bit information on other sub-carriers.

The merging formula needs further processing, and the I-path receiving value r corresponding to the same bit information s of the transmitting end is processed_IAnd Q-path reception value r_QAnd the following processes are uniformly carried out by combining the channel estimation values of the subcarriers where the signals are located:

the communication system has a module for channel estimation, which uses the known pilot frequency to calculate the channel state of the current communication signal, and in OFDM system, provides a channel estimation h for each sub-carrier, so that the h corresponding to the I path or Q path in the sub-carrier reception_IOr h_QFrom this channel estimate h, and the unavoidable background noise n_I；

The merging mode is as follows:

c can be 1, so that an improved scheme which accords with the MRC merging algorithm principle can be obtained to meet the signal-to-noise ratio optimal equalization mode under the special copy grading mode in the power line high-speed carrier communication frame control.

Based on the above algorithmic reasoning we can take the following steps accordingly:

first, we can get the channel estimation of all useful sub-carriers according to the preamble information in the communication system

h(k) k∈(0,N-1) (14)

N is the number of useful subcarriers;

secondly, according to the mapping rule of the diversity copy of the current control frame (the mapping rule of the diversity copy of the current control frame is established by a protocol, and the mapping is realized at a transmitting end, the technical scheme is characterized in that the mapping rule is restored at a receiving end) and the mapping rule table is as follows:

for originally transmitted bit information stream s ═ s₀,…,s₂₅₅After receiving end FFT, copy information combination is carried out (in the invention, after FFT, the real part and the imaginary part of frequency domain data are split, and the real part or the imaginary part corresponding to the same bit information is weighted and combined by using a channel estimation value); firstly, finding out I-path multiple received data r on different subcarriers in all OFDM symbols corresponding to current bit s_I(i) (these data are stored in dedicated buffers in the digital signal processor) to form a vector r_I(vector r)_IIs a one-dimensional vector composed of a plurality of real numbers) and estimates h the subcarrier channel corresponding to each I path at the same time_I(i) H (i) a composition vector h_I(vector h)_IIs a one-dimensional vector consisting of a plurality of channel estimate complex numbers);

thirdly, finding out Q paths of multiple received data r on different subcarriers in all OFDM symbols corresponding to the bit s_Q(q) the frequency domain data of all OFDM symbols after FFT are stored in the corresponding buffer of the digital signal processor, and the diversity reception signal needed by the bit s isStored at subcarrier locations specified by the protocol and called out to participate in diversity combining if desired) are formed into a vector r_Q(vector r)_QIs a one-dimensional vector composed of a plurality of real numbers); and simultaneously estimating the sub-carrier wave channels corresponding to each Q path_Q(q) h (q) a composition vector h_Q(subcarrier channel estimation h for each Q-path_Q(q) h (q) is obtained by the channel estimation device; vector h_QIs a one-dimensional vector consisting of a plurality of channel estimate complex numbers).

Fourthly, obtaining the combined output result of the optimal signal-to-noise ratio, namely the soft information input required by the decoder;

is the conjugate value of the corresponding channel estimation on the path I;

is the conjugate of the corresponding channel estimate on the Q-path;

in this technical solution, take the first bit as an example, and mark as s₀(ii) a From the rule table, s can be seen₀Mapped to subcarrier 0 in path I in OFDM symbol 1, subcarrier 128 in path Q in OFDM symbol 1, subcarrier 192 in path I in OFDM symbol 2, subcarrier 64 in path Q in OFDM symbol 2, subcarrier 160 in path I in OFDM symbol 3, subcarrier 32 in path Q in OFDM symbol 3, subcarrier 96 in path I in OFDM symbol 4, and subcarrier 224 in path Q in OFDM symbol 4, respectively. In total, 8 diversity transmissions are performed, and 8 reception values respectively corresponding to the reception ends are recorded as: r is_i1., 8, and the channel estimation values corresponding to the subcarriers where the 8 diversity transmissions are located are recorded as: h is_i1, 8; then diversity combining is carried out, and the maximum signal-to-noise ratio combining MRC combining method comprises the following steps:

herein, the

Is h_iConjugation of (1);

receiving a useful signal estimated value under the maximum signal-to-noise ratio receiving of a first bit;

the fifth step, for the rest bit information s₁,…,s₂₅₅Processing in the same way to obtain all the residual maximum SNR combined estimation values

The processing order of the bit information s is the information bit order required to be transmitted by the protocol, and the embodiment refers to 256 bits.

In addition, based on the above processing mode, we can see that the soft information obtained by the maximum snr combining mode does not need a constellation demodulation module at all, and directly sends the output to a decoder for decoding bit output. The processing method for BPSK and QPSK constellation mapping can be performed in this way. The method abandons the thinking that the traditional maximum signal-to-noise ratio receiving combination must be based on the subcarrier level and the limitation thereof, applies the technical processing means to the bit level category, greatly improves the application value of the maximum signal-to-noise ratio diversity receiving method, and is also beneficial to the flexibility of the diversity mapping mode of the code stream output by channel coding.

The invention is further described in a preferred embodiment in connection with fig. 1.

The invention provides a maximum signal-to-noise ratio diversity combining method of frame control information in power line high-speed carrier communication, wherein the frame control information occupies 4 OFDM symbols in total in the embodiment, each symbol occupies the same number of subcarriers, each subcarrier is divided into I-path information and Q-path information, and the I-path information and the Q-path information correspond to different bit data respectively and are shown in a rule table; FIG. 1 is a flow chart of an embodiment, with the following specific steps:

1. first, the channel estimation parameters of all available subcarriers are obtained by using the preamble information.

2. Starting from OFDM symbol 1, extracting data and corresponding sub-carrier position from each bit information of I-path signals in sequence according to a mapping mode specified by a protocol, and extracting data and sub-carrier position of I-path signals of OFDM symbols 2, 3 and 4 corresponding to the same bit information in the same mode. These data are combined into 2 one-dimensional vectors, respectively received data and subcarrier channel estimates corresponding to these data.

3. And extracting data and corresponding subcarrier positions from each bit information of the Q-path signals according to a mapping mode specified by a protocol in sequence, and extracting the data and the subcarrier positions of the Q-path signals of the OFDM symbols 2, 3 and 4 corresponding to the same bit information in the same mode. These data are combined into 2 one-dimensional vectors, respectively received data and subcarrier channel estimates corresponding to these data.

4. And integrating the vector values of each bit information diversity to all the paths I and Q to obtain complete received vector data r and a corresponding subcarrier channel estimation vector h.

5. The 2 parameters are multiplied by the maximum signal-to-noise ratio diversity combining mode of the invention to obtain combined output.

6. And repeating the 4 steps until all the original bit information is combined and output.

7. In this embodiment, there are 256 original bit streams, and different bit streams have different diversity times, but it can be seen from the embodiment of the present invention that diversity combining can be flexibly applied according to actual times without affecting the effect of the combining method.

The constellation point modulation information of this embodiment: the number of available carriers for frame control is 411, the number of subcarriers is from 80 to 490, and a QPSK modulation mode is adopted, and 4 frame control symbols exist. The 1 st symbol of frame control, for the I path, the input bit stream (256 bits) is copied to the corresponding carrier wave in sequence; for the Q path, the input bit stream (256 bits) is copied to the corresponding carrier by adding an offset of 128 until the copying of the available carrier is completed, that is, the bits with the bit number of (c +128) mod256 are sequentially filled in the effective sub-carriers, and the value of c is sequentially from 0 to 255. The 2 nd symbol of the frame control, for the I-path, the input bit stream (256 bits) plus an offset of 192 copies to the corresponding carrier; for the Q-path, the input bit stream (256 bits) plus a 64-offset is copied onto the corresponding carrier. Frame control 3 rd symbol, for I path, input bit stream (256 bits) plus a 160 offset is copied to the corresponding carrier; for the Q-path, the input bit stream (256 bits) is copied to the corresponding carrier plus a 32 offset. Frame-controlled 4 th symbol, for I-path, input bit stream (256 bits) plus a 96 offset is copied to the corresponding carrier; for the Q-path, the input bit stream (256 bits) is copied to the corresponding carrier plus a 224 offset. The detailed definition is as a rule table.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.