the technical solutions according to the embodiments of the invention will now be described clearly and fully in conjunction with the drawings in the embodiments of the invention . apparently , the embodiments described are only a part of the embodiments of the invention , rather than all the embodiments . based on the embodiments of the invention , all the other embodiments obtained by one of ordinary skill in the art without any inventive efforts are in the protection scope of the present invention . the embodiments of the invention will now be further illustrated by taking the ofdm modulation and demodulation technology as an example , in conjunction with the drawings . in embodiments of the invention , the frequency segments that cannot be used in the prior art are utilized to carry data , thus the channel resources may be fully utilized , and the joint transmission capacity of multiple line pairs may be increased . according to the value of the snr of each line pair , the corresponding frequency segments of which the snr is greater than or equal to 3 db are regarded as frequency segments that meet the bearer condition , and the corresponding frequency segments of which the snr is less than 3 db are regarded as frequency segments that do not meet the bearer condition . the information to be sent is divided into n + m ( m is greater than or is equal to 1 ) parts , where n parts of the information to be sent are carried on frequency segments of n line pairs that meet the bearer condition respectively ; in other words , n parts of the information to be sent are sent via n line pairs respectively and the existing mimo operating mode is employed . the remaining m parts of the information to be sent are carried repeatedly on at least two frequency segments that do not meet the bearer condition , in other words , any one of the m parts of the information to be sent may be transmitted via at least two frequency segments that do not meet the bearer condition on the same line pair ( for example , the frequency segments 805 , 806 and 807 in fig7 ), or may be transmitted via at least two frequency segments that do not meet the bearer condition on different line pairs ( for example , the frequency segments 801 and 803 in fig7 ). when the information sent is received , the recovery process of the n parts of the information sent also employs the existing mimo operating mode , i . e ., the n parts of the information sent are restored independently ; and for the recovery of the m parts of the information sent , the signals are first superimposed and then restored , i . e ., the signals that include the same part of the information sent ( specifically , it refers to the m parts of the information sent ) are superimposed by an adder , and then the m parts of the information sent are restored one by one . if there are four pairs of transmission lines , and according to the value of snr , the information to be sent is divided into 5 parts , which are marked as : c ( x 1 ), c ( x 2 ), c ( x 3 ), c ( x 4 ) and c ( xh ). the frequency segments that meet the bearer condition in line pair 1 , line pair 2 , line pair 3 and line pair 4 are used for carrying information c ( x 1 ), c ( x 2 ), c ( x 3 ) and c ( x 4 ). information c ( xh ) is carried repeatedly via at least two frequency segments that do not meet the bearer condition in line pair 1 , line pair 2 , line pair 3 and line pair 4 . for example , at least any two of the 8 frequency segments shown in fig7 are employed to carry information c ( xh ) repeatedly . the principle will now be described hereinafter , because the crosstalk signal is eliminated in the mimo technology , the influence of the crosstalk is no longer considered below . in fig8 , x 1 , x 2 , x 3 and x 4 represent the modulated signals of information c ( x 1 ), c ( x 2 ), c ( x 3 ) and c ( x 4 ) respectively , and xh represents the modulated signal of information c ( xh ). xh is superimposed with x 1 , x 2 , x 3 and x 4 respectively , and 4 sending signals x 1 + xh , x 2 + xh , x 3 + xh and x 4 + xh are formed , which are sent to the receiving end by four transmitters t 1 , t 2 , t 3 and t 4 respectively . h 1 , 1 , h 2 , 2 , h 3 , 3 , h 4 , 4 are transmission functions of 4 lines respectively , and the signals received by four receivers r 1 , r 2 , r 3 and r 4 are y 1 + yh 1 , y 2 + yh 2 , y 3 + yh 3 and y 4 + yh 4 respectively . yh 1 , yh 2 , yh 3 and yh 4 may be split from the received signal respectively via a frequency division method , thus yh 1 , yh 2 , yh 3 and yh 4 may be respectively represented as yh 1 = xh · h 1 , 1 + n 1 , yh 2 = xh · h 2 , 2 + n 2 , yh 3 = xh · h 3 , 3 + n 3 and yh 4 = xh · h 4 , 4 + n 4 , where n 1 , n 2 , n 3 and n 4 are white noises . these signals are added together at the receiving end to obtain the following : y ′= yh 1 + yh 2 + th 3 + yh 4 = xh ·( h 1 , 1 + h 2 , 2 + h 3 , 3 + h 4 , 4 )+( n 1 + n 2 + n 3 + n 4 ). the above formula is now qualitatively analyzed in view of signals . first of all , it is supposed that h 1 , 1 ≈ h 2 , 2 ≈ h 3 , 3 ≈ h 4 , 4 , the power component of the signal in the above formula is increased to 16 times of the original power component . because n 1 , n 2 , n 3 and n 4 are white noises and are independent with respect to each other , the power after they are added is increased to about 4 times of the original power . according to the computation formula of snr : it may be deduced that the power snr is increased by 6 db . in fig6 , the point of which the power snr is zero is point 204 , and after the snr is increased by 6 db , the frequency segments between point 103 and point 104 are now able to carry information of 2 db , as shown in fig9 . when there are many transmission lines for joint transmission , a part of the frequency points in fig6 that are higher than point 204 may also has an snr higher than 3 db , so they may also be used for carrying some information . a part of the frequency points , of which the frequency is higher than the frequency corresponding to point 204 and the snr is less than zero , may also be used for information transmission . in a similar way , the 8 frequency segments in fig7 may also be used for carrying the information to be transmitted . thus , the frequency segments that cannot be used in the prior art may be utilized for carrying data , so that the joint transmission capacity of multiple line pairs may be raised . fig1 shows a schematic diagram of the transmitting end according to this embodiment . for a transmission system with four pairs of transmission lines , the transmitting end includes : a first modulator group 101 including four ofdm demodulators 1 ; a second modulator ( i . e ., ofdm modulator 2 ) 102 ; an adder group 103 including four adders ; a d / a converter group 104 including four d / a converters ; and a transmitter group 105 including four transmitters . the four ofdm demodulators 1 are adapted to modulate the signals on frequency segments that meet the bearer condition , and the output terminals are connected with four adders respectively . the ofdm modulator 2 is specially adapted to modulate signals on frequency segments that do not meet the bearer condition , and the output terminal is also connected with the four adders respectively . the input terminals of the four d / a converters are respectively connected with the output terminals of the four adders , and the output terminals are respectively connected with four transmitters . moreover , all the d / a converter employ the same clock . when the transmitting end is in operation , the data to be sent ( the information to be sent ) are divided into 5 parts according to a bit table : c ( x 1 ), c ( x 2 ), c ( x 3 ), c ( x 4 ) and c ( xh ). the first four bit groups c ( x 1 ), c ( x 2 ), c ( x 3 ) and c ( x 4 ) are respectively modulated on frequency segments that meet the bearer condition using the same ofdm modulator 1 , and four modulated signals x 1 , x 2 , x 3 and x 4 are obtained . the bit group c ( xh ) is modulated on frequency segments that do not meet the bearer condition using ofdm modulator 2 , and a modulated signal xh is obtained . the modulated signal xh is respectively superimposed with the four modulated signals x 1 , x 2 , x 3 and x 4 by four adders . the four signals superimposed are converted by a d / a converter respectively , sent to different four pairs of transmission lines by drives t 1 , t 2 , t 3 and t 4 respectively , and then transmitted to the receiving end via four pairs of transmission lines . fig1 shows the schematic diagram ( 1 ) of the receiving end according to the embodiment . for a transmission system with four pairs of transmission lines , the receiving end includes : a receiver group 111 including four receivers r 1 , r 2 , r 3 and r 4 ; an a / d converter group 112 including four a / d converters using the same clock ; a first demodulator group 113 including four ofdm demodulators 1 ; an adder 114 ; and a second demodulator ( i . e ., ofdm demodulator 2 ) 115 . the output terminals of the four receivers are connected with the input terminals of the four a / d converters respectively . the first demodulator group 113 is adapted to demodulate and restore the information carried on the frequency segments that meet the bearer condition , and the input terminals are connected with the output terminals of the four ad converters respectively . the output terminals of the four a / d converters are also connected with the input terminal of the adder , and the output terminal of the adder is connected with the input terminal of the ofdm demodulator 2 . the second demodulator 115 is adapted to demodulate and restore the information carried on the frequency segments that do not meet the bearer condition . during operation , the receivers r 1 , r 2 , r 3 and r 4 respectively receive signals x 1 + xh , x 2 + xh , x 3 + xh and x 4 + xh from the lines , and an a / d transform is performed by the four a / d converters respectively . the four signals after the a / d transform are demodulated using the four ofdm demodulators 1 respectively . during the demodulation process , the information carried on the frequency segments that do not meet the bearer condition is discarded , and four parts of information c ′( x 1 ), c ′( x 2 ), c ′( x 3 ) and c ′( x 4 ) are obtained respectively . meanwhile , the four signals after and transform are superimposed by an adder as the fifth signal , and the fifth signal is demodulated using the second demodulator 115 . during the demodulation process , the information carried on the frequency segments that meet the bearer condition is discarded , and information c ′( xh ) is obtained . fig1 shows the schematic diagram ( 2 ) of the receiving end according to this embodiment . the difference between the schematic diagram ( 2 ) and the above schematic diagram ( 1 ) lies in that the four signals are demodulated by four ofdm demodulators in the first demodulator group 121 respectively ; and during the demodulation process , a fast fourier transform ( fft ) operation is first performed on the four signals , then a subcarrier screening is performed . thus the carrier data that carry information xh is separated from the carrier data that carry information x 1 , x 2 , x 3 and x 4 respectively , and four screened signals that carry the information xh and four screened signals that carry the information x 1 , x 2 , x 3 and x 4 respectively are obtained . the four screened signals that carry the information x 1 , x 2 , x 3 and x 4 are processed by a first constellation demapping module group 1211 in a first demodulator group 121 , and then the procedure directly turns to a series of subsequent demodulation processes such as constellation demapping and obtains the result c ′( x 1 ), c ′( x 2 ), c ′( x 3 ) and c ′( x 4 ). the four screened signals that carry the information xh are superimposed by an adder , and a series of demodulation processes such as constellation demapping are performed on the superimposed signal by a second constellation demapping module 1212 , and then the final result c ′( xh ) is obtained . fig1 shows a schematic diagram of the transmitting end and the receiving end according to this embodiment . the transmitting end includes : a modulator group 131 including four modulators ; a transmitter group 132 including four transmitters ; an encoder group 133 including ten encoders ; and a selector - combiner group 134 . the selector - combiner group 134 includes a selector 1341 and a combiner group 1342 including four combiners . ten output terminals of the encoder group 133 are respectively connected with ten input terminals of selector 1341 . four output terminals of the selector 1341 are respectively connected with the input terminals of the four combiners . the output terminals of the four combiners are respectively connected with the input terminals of the four modulators ; and the output terminals of the four modulators are respectively connected with the input terminals of the four transmitters . first of all , the encoder group 133 encodes information i to be sent into 10 encoded signals . the selector 1341 performs selection from the 10 encoded signals and physically combines the encoded signals with different coding gains that can be carried by each line pair . the combiner group 1342 logically combines the encoded signals with different coding gains and obtains four data streams . according to the value of snr of each line pair , the corresponding frequency segments of which the snr is greater than or equal to 3 db are taken as frequency segments that meet the bearer condition , and the corresponding frequency segments of which the snr is less than 3 db are taken as frequency segments that do not meet the bearer condition . the frequency segments that meet the bearer condition in the four line pairs are used for transmitting encoded signals with a low coding gain , and at least two frequency segments that do not meet the bearer condition in the four line pairs are used for transmitting encoded signals with a high coding gain , where the at least two frequency segments that do not meet the bearer condition may be at least two frequency segments that do not meet the bearer condition in the same line pair , or they may also be at least two frequency segments that do not meet the bearer condition in different line pairs . for example , for an encoded signal 1 , an encoded signal 2 and an encoded signal 3 , where the coding gain of the encoded signal 1 is greater than the coding gain of the encoded signal 2 , and the coding gain of the encoded signal 1 is greater than the coding gain of the encoded signal 3 , the selector 1341 selects the encoded signal 1 and the encoded signal 2 for physical combination , and selects the encoded signal 1 and the encoded signal 3 for physical combination . then the selector 1341 sends the encoded signal 1 and the encoded signal 2 together to the combiner 1 , and sends the encoded signal 1 and the encoded signal 3 together to the combiner 2 . the combiner 1 logically combines the encoded signal 1 and the encoded signal 2 and obtains a first data stream . the combiner 2 logically combines the encoded signal 1 and the encoded signal 3 and obtains a second data stream . the modulator 1 modulates these two data streams and sends the corresponding modulated signals to the transmitter 1 and the transmitter 2 . the transmitter 1 and the transmitter 2 send the two modulated signals to a first pair of transmission lines and a second pair of transmission lines respectively , where the frequency segments that meet the bearer condition on the first pair of transmission lines are used for transmitting the encoded signals with a low coding gain , i . e ., the encoded signal 2 , and the frequency segments that do not meet the bearer condition on the first pair of lines ( for example , the frequency segment 801 or the two frequency segments 801 and 802 as a whole as shown in fig7 ) are used for transmitting the encoded signals with a high coding gain , i . e ., the encoded signal 1 . the frequency segments that meet the bearer condition on the second pair of transmission lines are used for transmitting the encoded signals with a low coding gain , i . e ., the encoded signal 3 , and the frequency segments that do not meet the bearer condition on the second pair of lines ( for example , the frequency segment 803 as shown in fig7 ) are used for transmitting the encoded signals with a high coding gain , i . e ., the encoded signal 1 . the above 10 encoded signals are encoded by employing at least two encoding modes with different coding gains , such as reed - solomon ( rs ) encoding , low density parity code ( ldpc ) encoding . of course , the information to be sent may only be encoded for 5 times , as long as the number of encoding is larger than the pair number of the transmission lines . additionally , the encoders may be encoders of the same type with different parameters , or may be encoders of different types . the receiving end includes a demodulator group 135 , a receiver group 136 , a decoder group 137 , and a deselector - decombiner group 138 including a decombiner group and a deselector , where the receiver group 136 receives modulated signals from the four pairs of transmission lines and sends the modulated signals to the demodulator group 135 for demodulation , and obtains the above four data streams . the decombiner group 135 decombines these four data streams and logically separates the encoded signals with different coding gains . the deselector 1381 physically disassembles the encoded signals with different coding gains into the original 10 encoded signals according to the decombination result . taking the above encoded signal 1 , encoded signal 2 and encoded signal 3 as an example , the first data stream includes the encoded signal 1 and the encoded signal 2 , and the second data stream includes the encoded signal 1 and the encoded signal 3 , the decombiner 1 logically separates the encoded signal 1 and the encoded signal 2 in the first data stream . meanwhile , the decombiner 2 logically separates the encoded signal 1 and the encoded signal 3 in the second data stream . subsequently , the deselector physically separates the encoded signal 1 and the encoded signal 2 that are logically separated , and meanwhile physically separates the encoded signal 1 and the encoded signal 3 that are logically separated . the two encoded signals 1 are both sent to the corresponding decoder 1 for decoding , and the original information sent is obtained ; and the encoded signal 2 and the encoded signal 3 are also sent to the corresponding decoder 2 and the decoder 3 for decoding , and the original information i sent is obtained . in this embodiment , the encoder , selector and combiner in the transmitting end correspond to the decoder , deselector and decombiner in the receiving end . the encoding mode , selection policy and combination scheme employed for the information to be sent are commonly known for the transmitting end and the receiving end before the line works normally . the encoding mode , selection policy and combination scheme may be obtained through perform analysis according to the specific situation of the line on the receiving end , such as the frequency distribution of snr , or may be obtained by perform analysis according to the line situation on the transmitting end . no matter the encoding mode , selection policy and combination scheme are obtained through performing analysis on the transmitting end or on the receiving end , they must be notified to the opposite party by the generator before the line operates normally ; otherwise , the line cannot operate normally . additionally , it should be noted that one of ordinary skill in the art may understand that part or all of the processes for implementing the method according to the above embodiments may be accomplished by instructing related hardware via a program , and the program may be stored in a computer - readable storage medium , such as rom / ram , magnetic disc and compact disc . in conclusion , in solution 1 , an extra gain is obtained by generating redundancy via repeated sending , whereas in solution 2 , the gain is obtained by encoding or / and generating redundancy via repeated sending . the realization of solution 1 is simple , and can meet most of the situations . the realization of solution 2 is relatively complex , and can meet almost all the practical situations , where the gain generated by encoding is relatively large , and the transmission performance may be improved more apparently . in the embodiments of the invention , the low frequency band of multiple pairs of transmission lines is utilized for transmitting different signals ; moreover , the high frequency band of multiple pairs of transmission lines is also utilized for transmitting the same signal . therefore , the channel resources of the multiple line pairs are fully utilized , the joint transmission capacity of the multiple line pairs is increased , and the transmission rate of the multiple pairs of transmission lines is also increased at the same time . by using the method according to the embodiments of the invention , it may give a full play to the advantages of joint processing of multiple line pairs , and the performance is improved greatly in comparison with the performance of the existing mimo technology . under the same transmission rate , the signal transmission distance in the multiple line pairs technology may be increased by employing the solution of the invention . the contents described above are only embodiments and is intended to limit the protection scope of the present invention thereto . other embodiments that are obtained by one of ordinary skill in the art through modification , replacement or substitution based on the embodiments of the present invention without inventive efforts fall in the protection scope of the present invention .