CN102938753A - 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 of transmission method that is applicable to the super covering far away of Long Term Evolution enhancing LTE-A under low signal-to-noise ratio, with less rate loss, guarantee the transmission reliability of overlength distance user under low signal-to-noise ratio.

Background technology

Super far away the covering is that LTE-A strengthens a kind of scene that covers networking.In this scene, more than the base station covering radius need to reach 100km, 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 below 0dB, more much lower than receiving terminal average signal-to-noise ratio in normal cellular community.

Multiplexing BLAST when the transmission means of existing LTE-A is mainly space-frequency block codes SFBC and dblast.The former is at the N of N time slot _TrLaunch N on the root antenna _TrIndividual symbol, carry 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 _TrLaunch N on the root antenna _TrIndividual symbol, carry out spatial reuse, and receiving terminal adopts ZF ZF and least mean-square error MMSE detection algorithm to be detected.They are applicable in the cellular cell in the city of covering radius less 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 transmission of super covering far away, thereby must, for the lower situation of the super covering scene receiving terminal signal to noise ratio far away of LTE-A, considers a kind of suitable transmission plan.

Use orthogonal code sequence to transmit and there is the output signal-to-noise ratio that improves receiver and can carry bit information, thereby be widely used, for example the m-ary orthogonal code sequence.Based on These characteristics, can as the M-ary orthogonal coding, be applied in the super covering system far away of LTE-A to guarantee the reliability of transmission by orthogonal code sequence.

Under low signal-to-noise ratio, in order to overcome more serious noise effect, should choose completely orthogonal sequence sets closes, " fully quadrature " herein refers in set that every row orthogonal sequence and the correlation of self are sequence length, the i.e. code element number of an orthogonal code sequence, with the correlation of other sequences be 0 or negative.During the Walsh sequence sets closes, complete quadrature between each yard sequence, in CDMA systems, the general different channels of distinguishing the downlink communication link by Walsh code sequence, at some, in relevant research, utilize it can carry bit information and good their cross correlation thereof, using it as the M-ary orthogonal sequence.Yet the Bit Transmission Rate of Walsh code sequence is lower, still remain to be improved.

There is at present document to propose to adopt a kind of Walsh I/Q path quadrature sequence in Packet Radio Network, at I branch road and Q branch road, utilize respectively Walsh code sequence to carry out the M-ary orthogonal sequential coding, if the method is applied in the LTE-A system, when every carrier transmit power is identical, in Walsh code sequence that to reach with length be 16 under the condition of identical receiver output signal-to-noise ratio, this scheme is compared with the method that only adopts single branch road to carry out the M-ary orthogonal coding, and bit rate can promote 25%.

Said method can be communicated by letter comparatively reliably under low signal-to-noise ratio, compares its Bit Transmission Rate with the coding method of single branch road M-ary orthogonal and promotes to some extent, but still have the space of further lifting.

Summary of the invention

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

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

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

(1a) the Walsh sequence sets is closed to { { w _k(m) every row code sequence { w } } _k(m) } adjacent two are 1 or-1 symbol mapped is a complex symbol, obtain preliminary improved sequence sets and close { { p _k(n) } }, k=1 wherein, 2 ..., 2 ^MFor code sequence { w _k} and { p (m) _k(n) sequence number }, m=1,2 ..., 2 ^MFor code sequence { w _k(m) each code element w } _k(m) symbol number, n=1,2 ..., 2 ^M-1For code sequence { p _k(n) each code element p } _k(n) symbol number, M is that value is any nonnegative integer for adjusting the coefficient of code sequence number and length;

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

(2) at moment t, with improved orthogonal code sequence set { { p' in step (1) _i(n) the code sequence } } is carried out orthogonal coding to one group of bit information sequence { s (q) }, is about to { s (q) } and is mapped as { { p' _i(n) the improved orthogonal code sequence { p' of the row of one } } _I1(n) }, t=1,2 ... for moment sequence number, q=1,2 ..., the sequence number of the bit symbol s (q) that M+1 is the bit information sequence, i1 ∈ 1,2 ..., 2 ^M+1Close { { p' for sequence sets _i(n) } } sequence number of a row codes sequence wherein;

(3) on n orthogonal frequency division multiplex OFDM subcarrier of user's frequency range, the N of transmitting terminal _TrTransmit antennas is all launched orthogonal code sequence { p' _I1(n) the code element p' } _I1(n), this N _TrIndividual identical code element forms N _TrThe dimension emission signal vector:

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

N wherein _TrFor number of transmit antennas;

(4) on n subcarrier, N _recThe signal that the root reception antenna receives is N _recDimensional vector y (n)=H (t, n) x (n)+w (n), receiver carries out the least mean-square error detection to y (n), detects the signal of each transmission antennas transmit

J=1 wherein, 2 ..., N _TrFor transmitting antenna sequence number, N _recFor the reception antenna number, H (t, n) is the N on t moment n OFDM subcarrier _rec* N _TrThe dimension channel matrix, w (n) is N _recThe N that the root reception antenna receives _recDimension zero-mean white Gaussian noise vector;

(5) to the signal of detected each transmission antennas transmit

Carry out addition, 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) use unsentenced code element

Form unsentenced code sequence Will

Respectively with improved orthogonal code sequence set { { p' _i(n) each orthogonal code sequence { p' } } _i(n) } carry out related operation, obtain plural correlation $R_i=\underset{n=1}{\overset{2^{M-1}}{\mathrm{\Σ}}}\mathrm{conj}\left({p^{\′}}_i\left(n\right)\right)\hat{p}\left(n\right),i=\mathrm{1,2},...,2^{M+1},$ Conj () means to get conjugate operation;

(7) get correlation R _iReal part, and by the sequence number of the orthogonal code sequence of emission judgement be:

Be about to orthogonal code sequence i=1,2 ..., 2 ^M+1In corresponding to maximum Re (R _i) sequence number be assigned to

And think that the sequence number of orthogonal code sequence of emission is

Wherein, Re () means to get the real part computing, and max () means to get maximum operation;

(8) by the sequence number of judgement

Demapping is the information bit of judgement:

Wherein div () means to divide exactly computing, and mod () means to rem computing;

(9) use information bit

Form information bit sequence

One time transmitting procedure finishes.

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

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

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

The 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 is for carrying out error rate simulation result relatively by the improved orthogonal code sequence of the present invention and existing Walsh single-path quadrature code sequence;

Fig. 4 is for carrying out error rate simulation result relatively by the improved orthogonal code sequence of the present invention and existing Walsh I/Q path quadrature code sequence.

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 _TrThe root antenna, travelling carriage is receiving terminal, is equipped with N _recThe root antenna, the super channel far away in sea become when the channel between sending and receiving end is, wherein N _TrMean number of transmit antennas, N _recMean the reception antenna number.

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

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

(1a) the Walsh sequence sets is closed to { { w _k(m) every row code sequence { w } } _k(m) } adjacent two are 1 or-1 symbol mapped is a complex symbol, 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 preliminary improved sequence sets and close { { p _k(n) } },

K=1 wherein, 2 ..., 2 ^MFor code sequence { w _k} and { p (m) _k(n) sequence number }, m=1,2 ..., 2 ^MFor code sequence { w _k(m) each code element w } _k(m) symbol number, n=1,2 ..., 2 ^M-1For code sequence { p _k(n) each code element p } _k(n) symbol number, M is that value is any nonnegative integer for adjusting the coefficient of code sequence number and length;

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

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

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

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

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

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

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

R=1 wherein, 2 ..., 2 ^M-1For the code sequence group number of grouping, ⊙ means that each corresponding code element of two code sequences subtracts each other,

Mean each the corresponding code element addition of two code sequences, conj ^s{ } means each code element of code sequence is got to conjugation;

(1b2) with above-mentioned code sequence { p' _{4 (r-1)+1}(n) }, { p' _{4 (r-1)+2}(n) }, { p' _{4 (r-1)+3}} and { p' (n) _4r(n) } form final improved orthogonal code sequence set { { p' _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 improved orthogonal code sequence set { { p' in step 1 _i(n) the code sequence } } is carried out orthogonal coding to one group of bit information sequence { s (q) }, is about to { s (q) } and is mapped as { { p' _i(n) the improved orthogonal code sequence { p' of the row of one } } _I1(n) }, this mapping is with the code sequence number orthogonal code sequence { p' that is i1 by { s (q) } _I1(n) } substitute, i1 tries to achieve according to following formula:

$\mathrm{<figure-callout\; id="1"\; label="i"\; filenames="HDA00002444775900021.png,HDA00002444775900032.png"\; state="\{\{state\}\}">i</figure-callout>}1=\underset{q=1}{\overset{M+1}{\mathrm{\&Sigma;}}}s\left(q\right)2^{q-1},$

T=1 wherein, 2 ... for moment sequence number, i1 ∈ 1,2 ..., 2 ^M+1Close { { p' for sequence sets _i(n) } } sequence number of a row codes sequence wherein, s (q) is the bit symbol in information bit sequence { s (q) }, q=1,2 ..., the sequence number that M+1 is bit symbol s (q).

Step 3: on n orthogonal frequency division multiplex OFDM subcarrier of user's frequency range, the N of transmitting terminal _TrTransmit antennas is all launched orthogonal code sequence { p' _I1(n) the code element p' } _I1(n), this N _TrIndividual identical code element forms N _TrThe dimension emission signal vector:

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

N wherein _TrFor number of transmit antennas.

Step 4: on n subcarrier, N _recThe signal that the root reception antenna receives is N _recDimensional vector

Receiver carries out the least mean-square error detection to y (n), detects the signal of each transmission antennas transmit

J=1 wherein, 2 ..., N _TrFor transmitting antenna sequence number, N _recFor the reception antenna number, H (t, n) is the N on t moment n OFDM subcarrier _rec* N _TrThe dimension channel matrix, w (n) is N _recThe N that the root reception antenna receives _recDimension zero-mean white Gaussian noise vector.

Step 5: to the signal of detected each transmission antennas transmit

Carry out addition, and be averaged, obtain unsentenced code element $\hat{p}\left(n\right)=\frac{1}{N_{\mathrm{tr}}}\underset{j=1}{\overset{N_{\mathrm{tr}}}{\mathrm{\&Sigma;}}}{\hat{x}}_j\left(n\right).$

Step 6: use unsentenced code element

Form unsentenced code sequence

Will

Respectively with improved orthogonal code sequence set { { p' _i(n) each orthogonal code sequence { p' } } _i(n) } carry out related operation, obtain plural correlation:

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

Wherein, i=1,2 ..., 2 ^M+1, conj () means to get conjugate operation.

Step 7: get correlation R _iReal part, and by the sequence number of the orthogonal code sequence of emission judgement be:

Be about to orthogonal code sequence i=1,2 ..., 2 ^M+1In corresponding to maximum Re (R _i) sequence number be assigned to

And think that the sequence number of orthogonal code sequence of emission is

Wherein, Re () means to get the real part computing, and max () means to get maximum operation.

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 div () means to divide exactly computing, and mod () means to rem computing.

Step 9: use information bit

Form information bit sequence

One time transmitting procedure finishes.

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

1. simulation parameter configuration

The configuration of table 1 simulation parameter

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

2. emulation content

1) emulation 1

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

2) emulation 2

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

3. simulation result and theory analysis

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

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

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

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

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

Result and the theory analysis of emulation 2 show, improved orthogonal code sequence, when guaranteeing transmission reliability, is compared with existing Walsh I/Q path quadrature code sequence, and Bit Transmission Rate has improved 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) the orthogonal code sequence set of design improvement { { p'i (n) } }:

(1a) the Walsh sequence sets is closed to { { w _k(m) every row code sequence { w } } _k(m) } adjacent two are 1 or-1 symbol mapped is a complex symbol, obtain preliminary improved sequence sets and close { { p _k(n) } }, k=1 wherein, 2 ..., ^M2 is code sequence { w _k} and { p (m) _k(n) sequence number }, m=1,2 ..., 2 ^MFor code sequence { w _k(m) each code element w } _k(m) symbol number, n=1,2 ..., 2 ^M-1For code sequence { p _k(n) each code element p } _k(n) symbol number, M is that value is any nonnegative integer for adjusting the coefficient of code sequence number and length;

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

(2) at moment t, with improved orthogonal code sequence set { { p' in step (1) _i(n) the code sequence } } is carried out orthogonal coding to one group of bit information sequence { s (q) }, is about to { s (q) } and is mapped as { { p' _i(n) the improved orthogonal code sequence { p' of the row of one } } _I1(n) }, t=1,2 ... for moment sequence number, q=1,2 ..., the sequence number of the bit symbol s (q) that M+1 is the bit information sequence, i1 ∈ 1,2 ..., 2 ^M+1Close { { p' for sequence sets _i(n) } } sequence number of a row codes sequence wherein;

(3) on n orthogonal frequency division multiplex OFDM subcarrier of user's frequency range, the N of transmitting terminal _TrTransmit antennas is all launched orthogonal code sequence { p' _I1(n) the code element p' } _I1(n), this N _TrIndividual identical code element forms N _TrThe dimension emission signal vector:

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

N wherein _TrFor number of transmit antennas;

(4) on n subcarrier, N _recThe signal that the root reception antenna receives is N _recDimensional vector y (n)=H (t, n) x (n)+w (n), receiver carries out the least mean-square error detection to y (n), detects the signal of each transmission antennas transmit

J=1 wherein, 2 ..., N _TrFor transmitting antenna sequence number, N _recFor the reception antenna number, H (t, n) is the N on t moment n OFDM subcarrier _rec* N _TrThe dimension channel matrix, w (n) is N _recThe N that the root reception antenna receives _recDimension zero-mean white Gaussian noise vector;

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

(6) use unsentenced code element

Form unsentenced code sequence

Will

Respectively with improved orthogonal code sequence set { { p' _i(n) each orthogonal code sequence { p' } } _i(n) } carry out related operation, obtain plural correlation $R_i=\underset{n=1}{\overset{2^{M-1}}{\mathrm{\&Sigma;}}}\mathrm{conj}\left({p^{\&prime;}}_i\left(n\right)\right)\hat{p}\left(n\right),i=\mathrm{1,2},...,2^{M+1},$ Conj () means to get conjugate operation;

(7) get correlation R _iReal part, and by the sequence number of the orthogonal code sequence of emission judgement be:

Be about to orthogonal code sequence i=1,2 ..., 2 ^M+1In corresponding to maximum Re (R _i) sequence number be assigned to

And think that the sequence number of orthogonal code sequence of emission is

Wherein, Re () means to get the real part computing, and max () means to get maximum operation;

(8) the code sequence number that will adjudicate

Demapping is the information bit of judgement:

Wherein div () means to divide exactly computing, and mod () means to rem computing;

(9) use information bit

Form information bit sequence

One time transmitting procedure finishes.

2. the transmission method that is applicable to the super covering far away of LTE-A under low signal-to-noise ratio according to claim 1, wherein step (1a) is described closes { { w by the Walsh sequence sets _k(m) every row code sequence { w } } _k(m) } adjacent two are 1 or-1 symbol mapped is a complex symbol, 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 that is applicable to the super covering far away of LTE-A under low signal-to-noise ratio according to claim 1, wherein step (1b) is described closes { { p to preliminary improved sequence sets _k(n) } } carry out yard expansion of sequence number, carry out as follows:

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

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

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

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

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

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

R=1 wherein, 2 ..., 2 ^M-1For the code sequence group number of grouping, ⊙ means that each corresponding code element of two code sequences subtracts each other, Mean each the corresponding code element addition of two code sequences, conj ^s{ 2} means each code element of code sequence is got to conjugation;

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

4. the transmission method that is applicable to the super covering far away of LTE-A under low signal-to-noise ratio according to claim 1, wherein step (2) is described is mapped as { { p' by { s (q) } _i(n) the improved orthogonal code sequence { p' of the row of one } } _I1(n) be }, with the code sequence number orthogonal code sequence { p' that is i1 by { s (q) } _I1(n) } substitute, wherein i1 tries to achieve according to following formula:

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

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

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