CN102938753B - Transmission method suitable for long term evolution-advanced (LTE-A) over-distance covering under low signal to noise ratio - Google Patents

Abstract

The invention discloses a transmission method suitable for long term evolution-advanced (LTE-A) over-distance covering under a low signal to noise ratio, and mainly aims to solve the problem of relatively low bit transmission rate in the prior art. The method comprises the following steps of: (1) improving a Walsh code sequence set; (2) carrying out orthogonal coding on a bit information sequence by an improved orthogonal code sequence and emitting a code element of the orthogonal code sequence by a transmit diversity; (3) carrying out minimum mean square error detection on received signals, and adding and averaging the detected signals to obtain an orthogonal code sequence to be judged; and (4) carrying out the correlation operation on the orthogonal code sequence to be judged and all improved orthogonal code sequences to obtain the orthogonal code sequence number corresponding to the maximum correlation value of a real part, demapping the code sequence number into the bit information sequence, and ending the once transmitting process. According to the method, the error rate under a low signal to noise ratio is low, the data transmission is low and the transmission rate is high; and the method can be used for the signal transmission of the LTE-A over-distance covering under the low signal to noise ratio.

Description

Be applicable to the transmission method of the super covering far away of LTE-A under low signal-to-noise ratio

Technical field

The invention belongs to moving communicating field, be specifically related to a kind ofly be applicable to Long Term Evolution under low signal-to-noise ratio and strengthen the transmission method of the super covering far away of LTE-A, with the transmission reliability of less rate loss guarantee overlength distance user under low signal-to-noise ratio.

Background technology

Super far away covering is that LTE-A strengthens a kind of scene covering networking.In this scene, base station coverage radius needs to reach more than 100km, and transmission range is long, and path loss is large.In the super covering scene far away of LTE-A, the average received signal to noise ratio on each carrier wave is at below 0dB, more much lower than receiving terminal average signal-to-noise ratio in normal cellular community.

The transmission means of existing LTE-A mainly space-frequency block codes SFBC and dblast time multiplexing BLAST.The former is at the N of N number of time slot _trn launched by root antenna _trindividual symbol, carries out the diversity of room and time, and receiving terminal adopts maximum likelihood ML detection algorithm to carry out input; Latter is the N at same time slot _trn launched by root antenna _trindividual symbol, carries out spatial reuse, and receiving terminal adopts ZF ZF and least mean-square error MMSE detection algorithm to detect.They are applicable in the cellular cell in the relatively little city of covering radius or suburb.Under low signal-to-noise ratio, the error rate of these two kinds of transmission meanss is higher, is not suitable for the Signal transmissions of super covering far away, thus for the lower situation of the super covering scene receiving terminal signal to noise ratio far away of LTE-A, must consider a kind of suitable transmission plan.

Use orthogonal code sequence to carry out transmitting the output signal-to-noise ratio with raising receiver and the advantage that can carry bit information, be thus widely used, such as m-ary orthogonal code sequence.Based on These characteristics, can be applied in the super covering system far away of LTE-A to ensure the reliability transmitted as M-ary orthogonal coding by orthogonal code sequence.

Under low signal-to-noise ratio, in order to overcome more serious noise effect, completely orthogonal sequence sets should be chosen close, " completely orthogonal " herein refers to that in set, often row orthogonal sequence and the correlation of self are sequence length, the i.e. code element number of an orthogonal code sequence is 0 or negative with the correlation of other sequences.During Walsh sequence sets closes, completely orthogonal between each code sequence, in CDMA systems, general Walsh code sequence distinguishes the different channels of downstream communications link, in the research that some are relevant, then utilize it can carry bit information and good their cross correlation thereof, it can be used as M-ary orthogonal sequence.But the Bit Transmission Rate of Walsh code sequence is lower, still haves much room for improvement.

Document is had to propose in Packet Radio Network, adopt a kind of Walsh I/Q path quadrature sequence at present, Walsh code sequence is utilized to carry out M-ary orthogonal sequential coding respectively at I branch road and Q branch road, if the method is applied in lte-a system, when every carrier transmit power is identical, reaching with length under the condition of the identical receiver output signal-to-noise ratio of Walsh code sequence being 16, the program is carried out compared with the method for M-ary orthogonal coding with only adopting single spur track, and bit rate can promote 25%.

Said method can communicate comparatively reliably under low signal-to-noise ratio, and its Bit Transmission Rate promotes to some extent compared with the coding method of single spur track M-ary orthogonal, but still has the space promoted further.

Summary of the invention

The object of the invention is to propose that a kind of LTE-A be applicable under low signal-to-noise ratio is super far covers downlink transmission method, to ensure the reliability of transfer of data, promote Bit Transmission Rate further.

The technical thought realizing the object of the invention is: utilize the orthogonal code sequence improved to carry out M-ary orthogonal coding to original bit information, and apply orthogonal frequency division multiplex OFDM and multiple-input and multiple-output MIMO technology is transmitted, implementation step comprises as follows:

(1) orthogonal code sequence the set { { p' of design improvement _i(n) } }:

(1a) Walsh sequence sets is closed { { w _k(m) } } in often arrange code sequence { w _k(m) } adjacent two be 1 or-1 symbol mapped be a complex symbol, obtain the preliminary sequence sets improved and close { { p _k(n) } }, wherein k=1,2 ..., 2 ^mfor code sequence { w _k(m) } and { p _k(n) } sequence number, m=1,2 ..., 2 ^mfor code sequence { w _k(m) } in each code element w _kthe symbol number of (m), n=1,2 ..., 2 ^m-1for code sequence { p _k(n) } in each code element p _kthe symbol number of (n), M is the coefficient for adjustment code sequence number and length, and value is any nonnegative integer;

(1b) { { p is closed to the preliminary sequence sets improved _k(n) } } carry out a yard expansion for sequence number, obtain final orthogonal code sequence the set { { p' improved _i(n) } }, wherein i=1,2 ..., 2 ^m+1for code sequence { p' _i(n) } sequence number;

(2) at moment t, with orthogonal code sequence the set { { p' improved in step (1) _i(n) } } in code sequence pair one group of bit information sequence { s (q) } carry out orthogonal coding, be about to { s (q) } be mapped as { { p' _i(n) } } in one row improve orthogonal code sequence { p' _i1(n) }, t=1,2 ... for moment sequence number, q=1,2 ..., M+1 is the sequence number of bit symbol s (q) of bit information sequence, i1 ∈ 1,2 ..., 2 ^m+1be sequence sets conjunction { { p' _i(n) } } sequence number of a wherein row code sequence;

(3) on the n-th orthogonal frequency division multiplex OFDM subcarrier of user's frequency range, the N of transmitting terminal _trtransmit antennas all launches orthogonal code sequence { p' _i1(n) } in code element p' _i1(n), this N _trindividual identical code element forms N _trdimension emission signal vector:

$x\left(n\right)=\left[\begin{array}{c}{x}_1\left(n\right)\\ x_2\left(n\right)\\ .\\ .\\ .\\ x_{N_{\mathrm{tr}}}\left(n\right)\end{array}\right],x_1\left(n\right)=x_2\left(n\right)=...=x_{N_{\mathrm{tr}}}\left(n\right)={p^{\′}}_{i1}\left(n\right)$

Wherein N _trfor number of transmit antennas;

(4) on the n-th subcarrier, N _recthe signal that root reception antenna receives is N _recdimensional vector y (n)=H (t, n) x (n)+w (n), receiver carries out minimum mean-squared error algorithm to y (n), detects the signal of each transmission antennas transmit wherein j=1,2 ..., N _trfor transmitting antenna sequence number, N _recfor reception antenna number, H (t, n) is the N on t n-th OFDM subcarrier _rec× N _trdimension channel matrix, w (n) is N _recthe N that root reception antenna receives _recdimension zero mean Gaussian white noise vector;

(5) to the signal of each transmission antennas transmit detected be added, and be averaged, obtain unsentenced code element $\hat{p}\left(n\right)=\frac{1}{N_{\mathrm{tr}}}\underset{j=1}{\overset{N_{\mathrm{tr}}}{\mathrm{\Σ}}}{\hat{x}}_j\left(n\right);$

(6) unsentenced code element is used form unsentenced code sequence will respectively with orthogonal code sequence the set { { p' improved _i(n) } } in each orthogonal code sequence { p' _i(n) } carry out related operation, obtain the correlation of plural number $R_i=\underset{n=1}{\overset{2^{M-1}}{\mathrm{\Σ}}}\mathrm{conj}\left({p^{\′}}_i\left(n\right)\right)\hat{p}\left(n\right),i=\mathrm{1,2},...,2^{M+1},$ Conjugate operation is got in conj () expression;

(7) correlation R is got _ireal part, and by the sequence number of the orthogonal code sequence of transmitting judgement be: by orthogonal code sequence i=1,2 ..., 2 ^m+1in correspond to maximum Re (R _i) sequence number be assigned to and think that the sequence number of the orthogonal code sequence of launching is wherein, real part computing is got in Re () expression, and maximum operation is got in max () expression;

(8) by the sequence number of judgement demapping is the information bit of judgement: wherein computing is divided exactly in div () expression, and mod () represents the computing that rems;

(9) information bit is used composition information bit sequence one time transmitting procedure terminates.

The present invention compared with prior art has the following advantages:

1) transmission method of the present invention adopts the orthogonal code sequence improved to encode as M-ary orthogonal, and applies the technology such as OFDM and MIMO diversity and carry out transfer of data, and under low signal-to-noise ratio, the error rate is lower, ensure that the reliability of transfer of data;

2) compared with traditional Walsh code single-path quadrature code sequence and Walsh I/Q path quadrature code sequence, the bit number that each code element of m-ary orthogonal code sequence of the improvement designed in the present invention can carry increases to some extent, namely its Bit Transmission Rate promotes to some extent, and error performance loss is very little even almost constant.

Accompanying drawing explanation

Fig. 1 is the scene graph that the present invention uses;

Fig. 2 is realization flow figure of the present invention;

Fig. 3 carries out by orthogonal code sequence and existing Walsh single-path quadrature code sequence that the present invention improves the simulation result that the error rate compares;

Fig. 4 carries out by orthogonal code sequence and existing Walsh I/Q path quadrature code sequence that the present invention improves the simulation result that the error rate compares.

Embodiment

With reference to Fig. 1, application scenarios of the present invention is the common descending super covering far away in sea, and base station is transmitting terminal, is equipped with N _trroot antenna, travelling carriage is receiving terminal, is equipped with N _recroot antenna, the super channel far away in sea become when the channel between sending and receiving end is, wherein N _trrepresent number of transmit antennas, N _recrepresent reception antenna number.

With reference to Fig. 2, concrete steps of the present invention are as follows:

Step one: orthogonal code sequence the set { { p' of design improvement _i(n) } }:

(1a) Walsh sequence sets is closed { { w _k(m) } } in often arrange code sequence { w _k(m) } adjacent two be 1 or-1 symbol mapped be a complex symbol, namely use complex symbol substitute-1 and-1 two code element, use substitute 1 and-1 two code element, use substitute 1 and 1 two code element, use substitute-1 and 1 two code element, obtain the preliminary sequence sets improved and close { { p _k(n) } },

Wherein k=1,2 ..., 2 ^mfor code sequence { w _k(m) } and { p _k(n) } sequence number, m=1,2 ..., 2 ^mfor code sequence { w _k(m) } in each code element w _kthe symbol number of (m), n=1,2 ..., 2 ^m-1for code sequence { p _k(n) } in each code element p _kthe symbol number of (n), M is the coefficient for adjustment code sequence number and length, and value is any nonnegative integer;

(1b) { { p is closed to the preliminary sequence sets improved _k(n) } } carry out a yard expansion for sequence number, obtain final orthogonal code sequence the set { { p' improved _i(n) } }, concrete expansion is carried out as follows:

(1b1) orthogonal code sequence the set { { p will tentatively improved _k(n) } } in two adjacent code sequences be divided into one group, two the code sequences namely often organized are { p _{2 (r-1)+1}(n) }, { p _2r(n) }, every group code sequence number is expanded to 4 by 2, is respectively { p' _{4 (r-1)+1}(n) }, { p' _{4 (r-1)+2}(n) }, { p' _{4 (r-1)+3}(n) } and { p' _4r(n) }, that is:

First code sequence { p' _{4 (r-1)+1}(n) } be:

Second code sequence { p' _{4 (r-1)+2 (n)}be:

$\left\{{p^{\′}}_{4(r-1)+2}\left(n\right)\right\}=\left(\right\{p_{2(r-1)+1}\left(n\right)\}\⊕\{p_{2r}\left(n\right)\left\}\right)/\sqrt{2};$

3rd code sequence { p' _{4 (r-1)+3 (n)}be:

4th code sequence { p' _4r(n) } be:

Wherein r=1,2 ..., 2 ^m-1for the code sequence group number of grouping, ⊙ represents that the code element of two each correspondences of code sequence is subtracted each other, represent that the code element of two each correspondences of code sequence is added, conj ^s{ } expression gets conjugation to each code element of code sequence;

(1b2) with above-mentioned code sequence { p' _{4 (r-1)+1}(n) }, { p' _{4 (r-1)+2}(n) }, { p' _{4 (r-1)+3}(n) } and { p' _4r(n) } form final orthogonal code sequence the set { { p' improved _i(n) } },

Wherein, r=1,2 ..., 2 ^m-1, i=1,2 ..., 2 ^m+1for code sequence { p' _i(n) } sequence number.

Step 2: at moment t, with orthogonal code sequence the set { { p' improved in step one _i(n) } } in code sequence pair one group of bit information sequence { s (q) } carry out orthogonal coding, be about to { s (q) } be mapped as { { p' _i(n) } } in one row improve orthogonal code sequence { p' _i1(n) }, this mapping is the orthogonal code sequence { p' of i1 with code sequence number by { s (q) } _i1(n) } substitute, i1 tries to achieve according to following formula:

$i1=\underset{q=1}{\overset{M+1}{\mathrm{\Σ}}}s\left(q\right)2^{q-1},$

Wherein t=1,2 ... for moment sequence number, i1 ∈ 1,2 ..., 2 ^m+1be sequence sets conjunction { { p' _i(n) } } sequence number of a wherein row code sequence, s (q) is the bit symbol in information bit sequence { s (q) }, q=1,2 ..., M+1 is the sequence number of bit symbol s (q).

Step 3: on the n-th orthogonal frequency division multiplex OFDM subcarrier of user's frequency range, the N of transmitting terminal _trtransmit antennas all launches orthogonal code sequence { p' _i1(n) } in code element p' _i1(n), this N _trindividual identical code element forms N _trdimension emission signal vector:

$x\left(n\right)=\left[\begin{array}{c}{x}_1\left(n\right)\\ x_2\left(n\right)\\ .\\ .\\ .\\ x_{N_{\mathrm{tr}}}\left(n\right)\end{array}\right],x_1\left(n\right)=x_2\left(n\right)=...=x_{N_{\mathrm{tr}}}\left(n\right)={p^{\′}}_{i1}\left(n\right)$

Wherein N _trfor number of transmit antennas.

Step 4: on the n-th subcarrier, N _recthe signal that root reception antenna receives is N _recdimensional vector receiver carries out minimum mean-squared error algorithm to y (n), detects the signal of each transmission antennas transmit wherein j=1,2 ..., N _trfor transmitting antenna sequence number, N _recfor reception antenna number, H (t, n) is the N on t n-th OFDM subcarrier _rec× N _trdimension channel matrix, w (n) is N _recthe N that root reception antenna receives _recdimension zero mean Gaussian white noise vector.

Step 5: to the signal of each transmission antennas transmit detected be added, and be averaged, obtain unsentenced code element $\hat{p}\left(n\right)=\frac{1}{N_{\mathrm{tr}}}\underset{j=1}{\overset{N_{\mathrm{tr}}}{\mathrm{\Σ}}}{\hat{x}}_j\left(n\right).$

Step 6: use unsentenced code element form unsentenced code sequence will respectively with orthogonal code sequence the set { { p' improved _i(n) } } in each orthogonal code sequence { p' _i(n) } carry out related operation, obtain the correlation of plural number:

$R_i=\underset{n=1}{\overset{2^{M-1}}{\mathrm{\Σ}}}\mathrm{conj}\left({p^{\′}}_i\left(n\right)\right)\hat{p}\left(n\right),$

Wherein, i=1,2 ..., 2 ^m+1, conjugate operation is got in conj () expression.

Step 7: get correlation R _ireal part, and by the sequence number of the orthogonal code sequence of transmitting judgement be: by orthogonal code sequence i=1,2 ..., 2 ^m+1in correspond to maximum Re (R _i) sequence number be assigned to and think that the sequence number of the orthogonal code sequence of launching is wherein, real part computing is got in Re () expression, and maximum operation is got in max () expression.

Step 8: by the sequence number of judgement demapping is the information bit of judgement: $\hat{s}\left(q\right)=\mathrm{mod}\left[\mathrm{div}(\hat{i},2^{M+2-q})\right],$

Wherein computing is divided exactly in div () expression, and mod () represents the computing that rems.

Step 9: use information bit composition information bit sequence one time transmitting procedure terminates.

Effect of the present invention further illustrates by theory analysis and emulation.

1. simulation parameter configuration

Table 1 simulation parameter configures

Simulation time	100000ms
		Channel type	The super channel far away in sea
Channel estimating	Desirable
		Dual-mode antenna number	Receive for 42
Orthogonal code sequence length	16
		Transmission means	Transmit diversity
Receiving terminal detection mode	MMSE

2. emulate content

1) 1 is emulated

In the simulation time of 100000ms, at 4 transmit antennas, in the super channel far away in sea of 2 reception antennas, adopt transmission diversity radiation pattern and MMSE detection algorithm, the emulation that the Walsh code single-path quadrature sequence be orthogonal code sequence and the length of the improvement of 16 to length being 16 carries out bit error rate is compared, and simulation result as shown in Figure 3.

2) 2 are emulated

In the simulation time of 100000ms, at 4 transmit antennas, in the super channel far away in sea of 2 reception antennas, adopt transmission diversity radiation pattern and MMSE detection algorithm, compare with the emulation that Walsh I/Q path quadrature code sequence carries out bit error rate the orthogonal code sequence of the improvement by length being 16, simulation result as shown in Figure 4.

3. simulation result and theory analysis

In Fig. 3, curve Walsh16 Improved is the ber curve of the orthogonal code sequence that the present invention improves, and curve Walsh16 is the ber curve of existing Walsh single-path quadrature code sequence.As seen from Figure 3, the error rate of the two is all lower, and substantially identical.

But from the two being carried out to the theory analysis of Bit Transmission Rate, its sequence number of orthogonal code sequence that the present invention improves is 64=2 ⁶individual, therefore often row length be 16 code sequence can carry 6 bit informations, average each code element carrying 6/16=3/8 bit information, and the sequence number of existing Walsh code single-path quadrature sequence is only 16=2 ⁴individual, therefore often row length be 16 code sequence only carry 4 bit informations, average each code element carrying 4/16=1/4 bit information.

Result and the theory analysis of emulation 1 show, the orthogonal code sequence that the present invention improves is while guarantee transmission reliability, and compared with existing Walsh single-path quadrature code sequence, Bit Transmission Rate improves 50%.

In Fig. 4, curve Walsh16 Improved is the ber curve of the orthogonal code sequence that the present invention improves, and curve Walsh32I/Q is the ber curve of existing Walsh I/Q path quadrature code sequence.This result shows, the error rate of the two is all lower, and comparatively close.

But from the two being carried out to the theory analysis of Bit Transmission Rate, to the output signal-to-noise ratio making each branch road of Walsh I/Q path quadrature sequence reach close with the orthogonal code sequence improved, should arrange its length is 32, this I/Q branch road each branch road of encoding carries 5 bit informations, two branch roads can carry 10 bit informations altogether, i.e. average each code element carrying 10/32=5/16 bit information, and the average each code element of orthogonal code sequence improved can carry 3/8 bit information.

Result and the theory analysis of emulation 2 show, the orthogonal code sequence of improvement is while guarantee transmission reliability, and compared with existing Walsh I/Q path quadrature code sequence, Bit Transmission Rate improves 20%.

Claims (4)

1. be applicable to the transmission method of the super covering far away of LTE-A under low signal-to-noise ratio, comprise the steps:

(1) orthogonal code sequence the set { { p' of design improvement _i(n) } }:

(1a) Walsh sequence sets is closed { { w _k(m) } } in often arrange code sequence { w _k(m) } adjacent two be 1 or-1 symbol mapped be a complex symbol, obtain the preliminary sequence sets improved and close { { p _k(n) } }, wherein k=1,2 ..., 2 ^mfor code sequence { w _k(m) } and { p _k(n) } sequence number, m=1,2 ..., 2 ^mfor code sequence { w _k(m) } in each code element w _kthe symbol number of (m), n=1,2 ..., 2 ^m-1for code sequence { p _k(n) } in each code element p _kthe symbol number of (n), M is the coefficient for adjustment code sequence number and length, and value is any nonnegative integer;

(1b) { { p is closed to the preliminary sequence sets improved _k(n) } } carry out a yard expansion for sequence number, obtain final orthogonal code sequence the set { { p' improved _i(n) } }, wherein i=1,2 ..., 2 ^m+1for code sequence { p' _i(n) } sequence number;

(2) at moment t, with orthogonal code sequence the set { { p' improved in step (1) _i(n) } } in code sequence pair one group of bit information sequence { s (q) } carry out orthogonal coding, be about to { s (q) } be mapped as { { p' _i(n) } } in one row improve orthogonal code sequence { p' _i1(n) }, t=1,2 ... for moment sequence number, q=1,2 ..., M+1 is the sequence number of bit symbol s (q) of bit information sequence, i1 ∈ 1,2 ..., 2 ^m+1be sequence sets conjunction { { p' _i(n) } } sequence number of a wherein row code sequence;

(3) on the n-th orthogonal frequency division multiplex OFDM subcarrier of user's frequency range, the N of transmitting terminal _trtransmit antennas all launches orthogonal code sequence { p' _i1(n) } in code element p' _i1(n), this N _trindividual identical code element forms N _trdimension emission signal vector:

$x\left(n\right)=\left[\begin{array}{c}{x}_1\left(n\right)\\ x_2\left(n\right)\\ .\\ .\\ .\\ x_{N_{\mathrm{tr}}}\left(n\right)\end{array}\right]x_1\left(n\right)=x_2\left(n\right)=...=x_{N_{\mathrm{tr}}}\left(n\right)={p^{\′}}_{i1}\left(n\right)$

Wherein N _trfor number of transmit antennas;

(4) on the n-th subcarrier, N _recthe signal that root reception antenna receives is N _recdimensional vector y (n)=H (t, n) x (n)+w (n), receiver carries out minimum mean-squared error algorithm to y (n), detects the signal of each transmission antennas transmit wherein j=1,2 ..., N _trfor transmitting antenna sequence number, N _recfor reception antenna number, H (t, n) is the N on t n-th OFDM subcarrier _rec× N _trdimension channel matrix, w (n) is N _recthe N that root reception antenna receives _recdimension zero mean Gaussian white noise vector;

(5) to the signal of each transmission antennas transmit detected be added, and be averaged, obtain unsentenced code element $\hat{p}\left(n\right)=\frac{1}{N_{\mathrm{tr}}}\underset{j=1}{\overset{N_{\mathrm{tr}}}{\mathrm{\Σ}}}{\hat{x}}_j\left(n\right);$

(6) unsentenced code element is used form unsentenced code sequence will respectively with orthogonal code sequence the set { { p' improved _i(n) } } in each orthogonal code sequence { p' _i(n) } carry out related operation, obtain the correlation of plural number i=1,2 ..., 2 ^m+1, conjugate operation is got in conj () expression;

(7) correlation R is got _ireal part, and by the sequence number of the orthogonal code sequence of transmitting judgement be: by orthogonal code sequence i=1,2 ..., 2 ^m+1in correspond to maximum Re (R _i) sequence number be assigned to and think that the sequence number of the orthogonal code sequence of launching is wherein _,real part computing is got in Re () expression, and maximum operation is got in max () expression;

(8) by the code sequence number of judgement demapping is the information bit of judgement: wherein computing is divided exactly in div () expression, and mod () represents the computing that rems;

(9) information bit is used composition information bit sequence one time transmitting procedure terminates.

2. the transmission method of the super covering far away of LTE-A be applicable under low signal-to-noise ratio according to claim 1, closes { { w by Walsh sequence sets wherein described in step (1a) _k(m) } } in often arrange code sequence { w _k(m) } adjacent two be 1 or-1 symbol mapped be a complex symbol, namely use complex symbol substitute-1 and-1 two code element, use substitute 1 and-1 two code element, use substitute 1 and 1 two code element, use substitute-1 and 1 two code element.

3. the transmission method of the super covering far away of LTE-A be applicable under low signal-to-noise ratio according to claim 1, closes { { p to the preliminary sequence sets improved wherein described in step (1b) _k(n) } } carry out a yard expansion for sequence number, carry out as follows:

(1b1) orthogonal code sequence the set { { p will tentatively improved _k(n) } } in two adjacent code sequences be divided into one group, two the code sequences namely often organized are { p _{2 (r-1)+1}(n) }, { p _2r(n) }, every group code sequence number is expanded to 4 by 2, is respectively { p' _{4 (r-1)+1}(n) }, { p' _{4 (r-1)+2}(n) }, { p' _{4 (r-1)+3}(n) } and { p' _4r(n) }, that is:

First code sequence { p' _{4 (r-1)+1}(n) } be:

Second code sequence { p' _{4 (r-1)+2}(n) } be:

$\left\{{p^{\′}}_{4(r-1)+2}\left(n\right)\right\}=\left(\right\{p_{2(r-1)+1}\left(n\right)\}\⊕\{p_{2r}\left(n\right)\left\}\right)/\sqrt{2};$

3rd code sequence { p' _{4 (r-1)+3}(n) } be:

4th code sequence { p' _4r(n) } be:

Wherein r=1,2 ..., 2 ^m-1for the code sequence group number of grouping, represent that the code element of two each correspondences of code sequence is subtracted each other, ⊕ represents that the code element of two each correspondences of code sequence is added, conj ^s{ } expression gets conjugation to each code element of code sequence;

(1b2) with above-mentioned code sequence { p' _{4 (r-1)+1}(n) }, { p' _{4 (r-1)+2}(n) }, { p' _{4 (r-1)+3}(n) } and { p' _4r(n) } form final orthogonal code sequence the set { { p' improved _i(n) } }, r=1,2 ..., 2 ^m-1, i=1,2 ..., 2 ^m+1.

4. the transmission method of the super covering far away of LTE-A be applicable under low signal-to-noise ratio according to claim 1, is mapped as { { p' by { s (q) } wherein described in step (2) _i(n) } } in one row improve orthogonal code sequence { p' _i1(n) }, be the orthogonal code sequence { p' of i1 with code sequence number by { s (q) } _i1(n) } substitute, wherein i1 tries to achieve according to following formula:

$i1=\underset{q=1}{\overset{M+1}{\mathrm{\Σ}}}s\left(q\right)2^{q-1},$

Wherein s (q) is the bit symbol in information bit sequence { s (q) }, q=1,2 ..., M+1 is the sequence number of bit symbol s (q).