Method for avoiding transmission of side information by PTS in combination with channel estimation

Abstract

A method for avoiding transmission of side information by a Partial Transmit Sequence, comprising the following steps: Step 1: determining an indication sequence of a data sub-carrier and a pilot sub-carrier; Step 2: grouping the frequency domain data blocks including data and pilots to reduce the peak-to-average power ratio (PAPR) of the OFDM signal by phase rotation according to the PTS method. Step 3: processing the pilot of the received signal through channel estimation based on fast Fourier transform interpolation to obtain a frequency domain channel response, and extracting a phase rotation sequence. Step 4: equalizing the received data through the obtained frequency domain channel response. Step 5: performing inverse rotation of phase on the equalized data through the phase rotation information extracted in Step 3 to obtain transmitted data symbols.

Claims

1. A method for avoiding transmission of side information by a PTS in combination with channel estimation, comprising the following steps: Step 1: a transmitter determines an indication sequence of a data sub-carrier and a pilot sub-carrier; Step 2: frequency domain data blocks comprising data and pilots are grouped, and peak-to-average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) signal is reduced by phase rotation according to a Partial Transmit Sequence (PTS) method; Step 3: processing the pilot of the received signal through channel estimation based on fast Fourier transform (FFT) interpolation to obtain a frequency domain channel response, and extracting a phase rotation sequence of the transmitter; Step 4: equalizing the received data through the obtained frequency domain channel response; Step 5: performing inverse rotation of phase on the equalized data through the phase rotation information extracted in Step 3 to obtain transmitted data symbols.

2. The method for avoiding transmission of side information by a PTS in combination with channel estimation according to claim 1, wherein, in Step 1, the frequency domain data block is denoted as X=[X(0), X(1), . . . , X(N1)].sup., N is the number of sub-carriers, .sup. is transposition, X has N data and comprises L=N/4 pilots and NL quadrature amplitude modulation (QAM) symbols, L pilots are arranged on the 4l th sub-carrier, l=0, 1, . . . L1, and NL QAM symbols are arranged on other NL sub-carriers.

3. The method for avoiding transmission of side information by a PTS in combination with channel estimation according to claim 2, wherein Step 2 comprises the following steps: Step 21, dividing the frequency domain data block X into M subblocks, shown as: $X=\underset{m=0}{\overset{M-1}{.Math.}}.Math.X^m,$ where, M=4, X.sup.m=[X.sub.0.sup.m, X.sub.1.sup.m, . . . , X.sub.N1.sup.m] represents the mth subblock, m=0, 1, . . . , M1, the mth subblock X.sup.m where, the data X.sub.k.sup.m on k sub-carriers are shown as: $X_k^m=\{\begin{array}{cc}{X}_k,& m.Math..Math.N/Mk<\left(m+1\right).Math.N/M\\ 0,& \mathrm{others}\end{array}$ transforming X.sup.m to time domain through N IFFT to obtain the mth time domain signal x.sup.m, shown as:
x.sup.m=[x.sup.m(0), x.sup.m(1), . . . , x.sup.m(N1)], where, x.sup.m(N1) represents the N1th data of x.sup.m in the time domain; Step 22, producing a set containing U=4.sup.M phase rotation sequences .sub.u, shown as:
.sub.u=[W.sub.u.sup.0, W.sub.u.sup.1, . . . , W.sub.u.sup.M1], u=0, 1, . . . , U1, where W.sub.u.sup.m {1,1,j,j}, u represents the uth, W.sub.u.sup.m is a phase rotation coefficient, j={square root over (1)}; Step 23, according to U different phase rotation sequences .sub.u, performing phase rotation on x.sup.m to obtain U candidate signals {tilde over (x)}.sub.u, shown as: ${\tilde{x}}_u=\underset{m=0}{\overset{M-1}{.Math.}}.Math.W_u^m.Math.x^m,$ where, {tilde over (x)}.sub.u=[{tilde over (x)}.sub.u(0), {tilde over (x)}(1), . . . , {tilde over (x)}.sub.u(N1)] represents the uth candidate signal {tilde over (x)}.sub.u, calculating the PAPR.sub.u of U candidate signals, shown as: ${\mathrm{PAPR}}_u=\frac{\underset{0nN-1}{\max }.Math.\left[{.Math.{\tilde{x}}_u.Math.}^2\right]}{E\left[{.Math.{\tilde{x}}_u.Math.}^2\right]},$ where, n represents the nth point, 0nN1, |{tilde over (x)}.sub.u| is the absolute value of {tilde over (x)}.sub.u, and E[|{tilde over (x)}.sub.u|.sup.2] is the average value of |{tilde over (x)}.sub.u|.sup.2; Step 24, indicating the minimum PAPR.sub.u as PAPR* , indicating the signals of decreased PAPR as signal {tilde over (x)}*, indicating the corresponding phase rotation sequence as W*, and sending signals {tilde over (x)}*.

4. The method for avoiding transmission of side information by a PTS in combination with channel estimation according to claim 3, wherein Step 3 comprises the following steps: Step 31, indicating the received signals as r=[r(0), r(1), . . . , r(N1)], where r(N1) represents the N.sup.1th data in r, transforming the received signals r to frequency domain through fast Fourier transform (FFT) of N point to obtain frequency domain data block R=[R(0), R(1), . . . , R(N1)], where R(N1) is the N1th data of frequency domain data block R, R(k)={circumflex over (X)}(k)H(k)+W(k), R(k) is the kth data of frequency domain data block R, 0kN1, H(k) and W(k) are frequency domain channel response and noise on the kth sub-carrier respectively, and {circumflex over (X)}(k) is the data after phase rotation on the kth sub-carrier; Step 32, calculating the rotation channel response =[.sub.40, .sub.41, . . . , .sub.4(L1)] on L pilot sub-carriers through the pilot, shown as: ${\hat{H}}_k=\frac{R\left(k\right)}{X_p\left(k\right)},.Math.k=4.Math.l,l=0,1,\mathrm{.Math.}.Math.,L-1,$ where, X.sub.p(k) is the pilot on the kth sub-carrier; Step 33, dividing rotation channel response into M groups, shown as: $\hat{H}=\underset{m=0}{\overset{M-1}{.Math.}}.Math.{\hat{H}}^m,$ where .sup.m=[.sub.0.sup.m, .sub.1.sup.m, . . . , .sub.L1.sup.m] represents the mth group, the length is L, .sub.l.sup.m represents the lth point in .sup.m, 0lL1 and .sub.l.sup.m are shown as: ${\hat{H}}_i^m=\{\begin{array}{cc}{\hat{H}}_{l*L/M},& m.Math..Math.L/Ml<\left(m+1\right).Math.L/M\\ 0,& \mathrm{others}\end{array}.$ utilizing L point IFFT to transform .sup.m to time domain to obtain the channel rotation impulse response .sup.m=[.sup.m(0), .sup.m(1), . . . , .sup.m(L1)] corresponding to .sup.m, where .sup.m(L1) represents the L1th data in .sup.m; Step 34, performing phase inverse rotation on .sup.m, m=0, 1, . . . M1 through phase inverse rotation sequence .sub.u to obtain U candidate signals, shown as: ${\tilde{h}}_u=\underset{m=0}{\overset{M-1}{.Math.}}.Math.W_u^{.Math..Math.m}.Math.{\hat{h}}^m,u=0,1,\mathrm{.Math.}.Math.,U-1,$ where, is conjugate, .sub.u is the vector of conjugate of .sub.u, {tilde over (h)}.sub.u=[{tilde over (h)}.sub.u(0), {tilde over (h)}.sub.u(1), . . . , {tilde over (h)}.sub.u(L1)], calculating the minimum Tail.sub.u of {tilde over (h)}.sub.u tail signal, shown as ${\mathrm{Tail}}_u=\underset{L-QnL-1}{\min }.Math..Math.{\tilde{h}}_u.Math.,$ where, Q is an integer and is set to Q=4; Step 35, indicating the minimum Tail.sub.u as Tail*, and indicating the corresponding phase inversion rotation sequence as *; Step 36, calculating the actual channel impulse response $\hat{h}=\underset{m=0}{\overset{M-1}{.Math.}}.Math.W_u^{.Math..Math.m}.Math.{\hat{h}}^m$ through *=[W*.sup.0, W*.sup.1, . . . , W*.sup.M1], adding (NL) zeros behind to obtain $h=\left[\hat{h},\underset{\underset{N-L}{}}{0,0,\mathrm{.Math.}.Math.,0}\right],$ and working out FFT of N point on h to obtain channel response H=[H(0), H(1), . . . , H(N1)]on N sub-carriers, where H(N1) is the N1th data in H.

5. The method for avoiding transmission of side information by a PTS in combination with channel estimation according to claim 4, wherein zero-forcing equalization (ZF) or minimum mean square error equalization (MMSE) are performed on frequency domain data to obtain transmitted data symbol blocks X=X(0), X(1), . . . , X(N1), X(k) represents the kth data in X, and 0kN1, and X(k) are shown as: $\stackrel{\_}{X}\left(k\right)=\{\begin{array}{cc}\frac{R\left(k\right)}{\stackrel{\_}{H}\left(k\right)}& \mathrm{ZF}\\ \frac{R\left(k\right){\stackrel{\_}{H}}^{}\left(k\right)}{{.Math.\stackrel{\_}{H}\left(k\right).Math.}^2+}& \mathrm{MMSE}\end{array},$ where, is reciprocal of signal-to-noise ratio.

6. The method for avoiding transmission of side information by a PTS in combination with channel estimation according to claim 5, wherein Step 5 comprises the following steps: Step 51, dividing X into M subblocks, shown as: $\stackrel{\_}{X}=\underset{m=0}{\overset{M-1}{.Math.}}.Math.{\stackrel{\_}{X}}^m,$ where, X.sup.m=[X.sup.m(0), X.sup.m(1), . . . , X.sup.m(N1)] is the mth subblock, shown as: ${\stackrel{\_}{X}}_k^m=\{\begin{array}{cc}{\stackrel{\_}{X}}_k,& m.Math..Math.N/Mk<\left(m+1\right).Math.N/M\\ 0,& \mathrm{others}\end{array}$ where, X.sub.k.sup.m represents the data on the kth sub-carrier in X.sup.m of the mth subblock, Step 52: performing phase inversion rotation of X.sup.m to obtain transmitted data block X, shown as: $X=\underset{m=0}{\overset{M-1}{.Math.}}.Math.W_{*}^m.Math.{\stackrel{\_}{X}}^m.$

Description

BRIEF DESCRIPTION OF DRAWINGS

[0041] The advantages of the above and/or other aspects of the present invention will become more apparent from the following further detailed description of the invention when taken in conjunction with the accompanying drawings and specific embodiments.

[0042] FIG. 1 is a flowchart of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0043] As shown in FIG. 1, the invention provides a method for avoiding transmission of side information by a PTS in combination with channel estimation, including the following steps:

[0044] Step 1: the transmitter determines an indication sequence of the data sub-carrier and the pilot sub-carrier;

[0045] Step 2: grouping frequency domain data blocks including data and pilots, and reducing the PAPR of the OFDM signal by phase rotation according to the PTS method;

[0046] Step 3: processing pilot of the received signal through channel estimation based on fast Fourier transform (FFT) interpolation to obtain a frequency domain channel response, and extracting a phase rotation sequence of the transmitter;

[0047] Step 4: equalizing the received data through the obtained frequency domain channel response;

[0048] Step 5: performing inverse rotation of phase on the equalized data through the phase rotation information extracted in Step 3 to obtain transmitted data symbols.

[0049] In Step 1, the frequency domain data block is denoted as X=[X(0), X(1), . . . , X(N1)].sup., N is the number of sub-carriers, .sup. is transposition, X has N data and includes L=N/4 pilots and NL quadrature amplitude modulation (QAM) symbols, L pilots are arranged on the 4lth sub-carrier, l=0, 1, . . . L1, and NL QAM symbols are arranged on other NL sub-carriers.

[0050] Step 2 includes the following steps:

[0051] Step 21, dividing the frequency domain data block X into M subblocks, shown as:

[00016]$X=\underset{m=0}{\overset{M-1}{.Math.}}.Math..Math.X^m,$

[0052] where, M=4, X.sup.m=[X.sub.0.sup.m, X.sub.1.sup.m, . . . , X.sub.N1.sup.m] represents the mth subblock, m=0, 1, . . . , M1, the mth subblock X.sup.m

[0053] where, the data X.sub.k.sup.m on k sub-carriers are shown as:

[00017]$X_k^m=\{\begin{array}{cc}{X}_k,& m.Math..Math.N.Math.\text{/}.Math.Mk<\left(m+1\right).Math.N.Math.\text{/}.Math.M\\ 0,& \mathrm{others}\end{array}$

[0054] transforming X.sup.m to time domain through N IFFT to obtain the mth time domain signal x.sup.m, shown as:

x.sup.m=[x.sup.m(0), x.sup.m(1), . . . , x.sup.m(N1)],

[0055] where, x.sup.m(N1) represents the N1th data of x.sup.m in the time domain;

[0056] Step 22, producing a set containing U=4.sup.M phase rotation sequences .sub.u, shown as:

.sub.u=[W.sub.u.sup.0, W.sub.u.sup.1, . . . , W.sub.u.sup.M1], u=0, 1, . . . , U1,

where W.sub.u.sup.m {1,1,j,j}, u represents the uth, W.sub.u.sup.m is a phase rotation coefficient, j={square root over (1)};

[0057] Step 23, according to U different phase rotation sequences .sub.u, performing phase rotation on x.sup.m to obtain U candidate signals {tilde over (x)}.sub.u, shown as:

[00018]${\tilde{x}}_u=\underset{m=0}{\overset{M-1}{.Math.}}.Math.W_u^m.Math.x^m,$

[0058] where, {tilde over (x)}.sub.u=[{tilde over (x)}.sub.u(0), {tilde over (x)}.sub.u(1), . . . , {tilde over (x)}.sub.u(N1)] represents the uth candidate signal {tilde over (x)}.sub.u, calculating the PAPR.sub.u of U candidate signals, shown as:

[00019]${\mathrm{PAPR}}_u=\frac{\underset{0nN-1}{\max }.Math.\left[I.Math.{\tilde{x}}_u.Math.I^2\right]}{E\left[I.Math.{\tilde{x}}_u.Math.I^2\right]},$

[0059] where, n represents the nth point, 0nN1, |{tilde over (x)}.sub.u| is the absolute value of {tilde over (x)}.sub.u, and E[|{tilde over (x)}.sub.u|.sup.2] is the average value of |{tilde over (x)}.sub.u|.sup.2;

[0060] Step 24, indicating the minimum PAPR.sub.u as PAPR*, indicating the signals of decreased PAPR as signal {tilde over (x)}*, indicating the corresponding phase rotation sequence as W*, and sending signals {tilde over (x)}*.

[0061] Step 3 includes the following steps:

[0062] Step 31, indicating the received signals as r=[r(0), r(1), . . . , r(N1)], where r(N1) represents the N1th data in r, transforming the received signals r to frequency domain through fast Fourier transform (FFT) of N point to obtain frequency domain data block R=[R(0), R(1), . . . , R(N1)], where R(N1) is the N1th data of frequency domain data block R, R(k)={circumflex over (X)}(k)H(k)+W(k), R(k) is the kth data of frequency domain data block R, 0kN1, H(k) and W(k) are frequency domain channel response and noise on the kth sub-carrier respectively, and {circumflex over (X)}(k) is the data after phase rotation on the kth sub-carrier;

[0063] Step 32, calculating the rotation channel response =[.sub.40, .sub.41, . . . , .sub.4(L1)] on L pilot sub-carriers through the pilot, shown as:

[00020]${\hat{H}}_k=\frac{R\left(k\right)}{X_p\left(k\right)},k=4.Math..Math.l,l=0,1,\mathrm{.Math.}.Math.,L-1,$

[0064] where, X.sub.p(k) is the pilot on the kth sub-carrier;

[0065] Step 33, dividing rotation channel response into M groups, shown as:

[00021]$\hat{H}=\underset{m=0}{\overset{M-1}{.Math.}}.Math.{\hat{H}}^m,$

[0066] where .sup.m=[.sub.0.sup.m, .sub.1.sup.m, . . . , .sub.L1.sup.m] represents the mth group, the length is L, .sub.l.sup.m represents the lth point in .sup.m, 0lL1 and .sub.l.sup.m are shown as:

[00022]${\hat{H}}_l^m=\{\begin{array}{cc}{\hat{H}}_{l*L/M},& m.Math..Math.L.Math.\text{/}.Math.Ml<\left(m+1\right).Math.L.Math.\text{/}.Math.M\\ 0,& \mathrm{others}\end{array}$

[0067] utilizing L point IFFT to transform .sup.m to time domain to obtain the channel rotation impulse response .sup.m=[.sup.m(0), .sup.m(1), . . . , .sup.m(L1)] corresponding to .sup.m, where .sup.m(L1) represents the L1th data in .sup.m;

[0068] Step 34, performing phase inverse rotation on .sup.m, m=0, 1, . . . , M1 through phase inverse rotation sequence .sub.u to obtain U candidate signals, shown as:

[00023]${\tilde{h}}_u=\underset{m=0}{\overset{M-1}{.Math.}}.Math.W_u^{.Math..Math.m}.Math.{\hat{h}}^m,u=0,1,\mathrm{.Math.}.Math.,U-1,$

[0069] where, is conjugate, .sub.u is the vector of conjugate of .sub.u, {tilde over (h)}.sub.u=[{tilde over (h)}.sub.u(0), {tilde over (h)}.sub.u(1), . . . , {tilde over (h)}.sub.u(L1)], calculating the minimum Tail.sub.u of {tilde over (h)}.sub.u tail signal, shown as

[00024]${\mathrm{Tail}}_u=\underset{L-QnL-1}{\min }.Math..Math.{\tilde{h}}_u.Math.,$

[0070] where, Q is an integer and is set to Q=4,

[0071] Step 35, indicating the minimum Tail.sub.u as Tail*, and indicating the corresponding phase inversion rotation sequence as *;

[0072] Step 36, calculating the actual channel impulse response

[00025]$\hat{h}=\underset{m=0}{\overset{M-1}{.Math.}}.Math.W_{*}^{.Math..Math.m}.Math.{\hat{h}}^m$

through *=[W*.sup.0, W*.sup.1, . . . , W*.sup.M1], adding (NL) zeros behind to obtain

[00026]$h=\left[\hat{h},\underset{\underset{N-L}{}}{0,0,\mathrm{.Math.}.Math.,0}\right],$

and working out FFT of N point on h to obtain channel response H=[H(0), H(1), . . . , H(N1)] on N sub-carriers, where H(N1) is the N1th data in H.

[0073] In Step 4, zero-forcing equalization (ZF) or minimum mean square error equalization (MMSE) are performed on frequency domain data to obtain transmitted data symbol blocks X=[X(0), X(1), . . . , (N1)], X(k) represents the kth data in X, and 0kN1, and X(k) are shown as:

[00027]$\stackrel{\_}{X}\left(k\right)=\{\begin{array}{cc}\frac{R\left(k\right)}{\stackrel{\_}{H}\left(k\right)},& Z.Math..Math.F\\ \frac{R\left(k\right){\stackrel{\_}{H}}^{}\left(k\right)}{{.Math.\stackrel{\_}{H}\left(k\right).Math.}^2+},& \mathrm{MMSE}\end{array},$

[0074] where, is reciprocal of signal-to-noise ratio.

[0075] Step 5 includes the following steps:

[0076] Step 51, dividing Xinto M subblocks, shown as:

[00028]$\stackrel{\_}{X}=\underset{m=0}{\overset{M-1}{.Math.}}.Math.{\stackrel{\_}{X}}^m,$

[0077] where, X.sup.m=X.sup.m(0), X(1), . . . , X.sup.m(N1) is the mth subblock, shown as:

[00029]${\stackrel{\_}{X}}_k^m=\{\begin{array}{cc}{\stackrel{\_}{X}}_k,& m.Math..Math.N.Math.\text{/}.Math.Mk<\left(m+1\right).Math.N.Math.\text{/}.Math.M\\ 0,& \mathrm{others}\end{array}$

[0078] where, X.sub.k.sup.m represents the data on the kth sub-carrier in X.sup.m of the mth subblock,

[0079] Step 52: performing phase inversion rotation of X.sup.m to obtain transmitted data block X, shown as:

[00030]$X=\underset{m=0}{\overset{M-1}{.Math.}}.Math.W_{*}^m.Math..Math.{\stackrel{\_}{X}}^m.$

[0080] The present invention will be described in more detail below by way of embodiments, but the following examples are merely illustrative and the scope of protection of the present invention is not limited by these embodiments.

Embodiment 1

[0081] Parameter Description:

[0082] In Step 1, the number of sub-carriers of the system is N=1024, the number of pilots is L=256, and the constellation mapping mode is 4QAM;

[0083] In Step 2, M=4,: the frequency domain data block is divided into 4 subblocks, and the number of phase rotation sequences is U=256; after phase rotation of the frequency domain data block, 256 different candidate sequences are obtained, and then the sequence with the lowest PAPR is selected as an optimal sequence, which is then sent out;

[0084] In Step 3, the 256-point pilot is used to estimate the channel response in frequency domain, and the 256-point channel response is divided into 4 groups; then the channel response in frequency domain is inversely rotated by U=256 inverted phase rotation sequences, and the phase rotation sequences of the transmitter are extracted to obtain the actual channel response;

[0085] In Step 4, equalizing the frequency domain data blocks according to the real channel response;

[0086] In Step 5, dividing the equalized frequency domain data block into 4 subblocks, and performing phase inverse rotation on the subblocks.

[0087] The simulation results show that the invention can ensure that the BER is not affected while ensuring the performance of the PAPR reduction, meanwhile avoiding the transmission of the side information, thereby improving the throughput of the system.

[0088] The PAPR can be reduced by 5.5 dB, and the SNR is 12 dB when BER=10.sup.5. The data rate and the bit error rate performance of the present invention after decreasing PAPR are the same as those of the signals before decreasing the PAPR.

[0089] The foregoing is only a preferred embodiment of the present invention, but the present invention should not be limited to the contents disclosed in this embodiment and the accompanying drawings. Therefore, equivalents or modifications made without departing from the spirit of the present invention shall fall within the scope of the present invention.