CN103581917A - Frequency spectrum coexisting method and frequency spectrum processing device used for OFDM system - Google Patents

Abstract

The invention discloses a frequency spectrum coexisting method and frequency spectrum processing device used for an OFDM system. The method comprises the steps of calculating the coefficient matrixes of the positions where the frequency of the OFDM system is overlapped with the frequency of each coexisting system and obtaining power influence of other carrier sidelobes in the OFDM system at the frequency coexisting positions according to the coefficient matrixes; obtaining and pre-storing a reconstructed subcarrier matrix corresponding to each coexisting system; calculating a reconstructed subcarrier sequence according to the reconstructed subcarrier matrixes, and inserting the reconstructed subcarrier sequence into an original data sequence of the OFDM system to form a trapped wave. According to the frequency spectrum coexisting method and frequency spectrum processing device used for the OFDM system, due to the fact that the reconstructed subcarrier data are inserted to form the OFDM frequency spectrum dip, power of other subcarrier sidelobes is offset, the trapped wave is deepened, and mutual interference between the OFDM system and other coexisting systems is avoided.

Description

Frequency spectrum coexistence method and frequency spectrum processing device for ofdm system

Technical field

The present invention relates to mobile communication application technical field, relate in particular to a kind of frequency spectrum coexistence method for ofdm system and frequency spectrum processing device.

Background technology

Along with people strengthen the demand of high-speed radio transmission, various new wireless communication systems are with a large bandwidth and at a high rate born one after another, Long Term Evolution), WiMax (Worldwide Interoperability for Microwave Access) and WiGig(Wireless Gigabit such as 802.11n, LTE(Long Term Evolution:: wireless gigabit) etc., and most of high-speed radiocommunication system wherein has all been used orthogonal frequency division multiplex OFDM (Orthogonal frequency-division multiplexing) technology.Be accompanied by the rise of mobile Internet, the wireless transmission demand of video, large transfer of data grows with each passing day, following take above-mentioned wireless communication technology and will inevitably improve greatly the number of devices of access network as basic system, huge wireless access amount can cause it to the demand of frequency spectrum, can not be carried by mobile communication and wireless access frequency in existing dividing frequency or planning, and therefore how solving the frequency spectrum of wireless communication technology in future development problem in short supply is also one of emphasis of research.

For this problem, in recent years, except avoiding the conventional method of existing wireless system frequency, also there is cognitive radio (CR) technology, its basic thought is mutual by with operational environment, changes the transmitter parameter of wireless device, to reach the object coexisting with other system spectrum.If an OFDM wireless communication system is according to the mobile communication system signal of perception, under its active state, take the mode of manufacturing spectral notch to avoid interference mobile communication system; Under non-active state, ofdm system full-load run, thus make same section of frequency spectrum meet the needs of two kinds of systems.But for ofdm system, iff closing the subcarrier that has spectrum signal conflict interference place, the impact due to other subcarrier secondary lobe power, can not reach good spectral notch, realization is simultaneously also more complicated, has limited to the effect that frequency spectrum coexists.

Summary of the invention

In view of this, the technical problem that the present invention will solve is to provide a kind of frequency spectrum coexistence method for ofdm system, by inserting reconstruct subcarrier data, forms OFDM spectral notch, avoids mutually disturbing with symbiotic system.

A frequency spectrum coexistence method for ofdm system, calculates ofdm system and symbiotic system at the coefficient matrix at frequency overlap place, according to described coefficient matrix, obtains in described ofdm system other subcarrier secondary lobe in the power influences at frequency place that coexists; Obtain the reconstruct subcarrier matrix corresponding to each symbiotic system, and make pre-stored; According to described reconstruct subcarrier matrix computations reconstruct subcarrier sequence, and described reconstruct subcarrier sequence is inserted in the former data sequence of described ofdm system, formed trap.

According to one embodiment of the method for the invention, further, described calculating ofdm system and the coefficient matrix of symbiotic system at frequency overlap place are specially: according to the characteristics of signals of symbiotic system, select the sampling multiple M of signal and the number of reconstruct subcarrier; Described ofdm system signal is carried out to M sampling, obtain ofdm signal frequency spectrum, described frequency spectrum is:

$Y\left(l\right)=\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)\exp (-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA00001938383700031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{n}{N}\frac{l}{M});$

Wherein, N represents ofdm system subcarrier number, and x (n) is QPSK mapping symbols, and l is total number of sample points; According to described frequency spectrum, draw the coefficient matrix P of ofdm signal; The matrix that described coefficient matrix P is MN * N, each element in described coefficient matrix P is:

$p(l,k)={\mathrm{\&Sigma;}}_{n=0}^{N-1}\exp \left(\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA00001938383700031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{n}{N}(k-\frac{l}{M})\right).$

According to one embodiment of the method for the invention, further, describedly obtain corresponding to the reconstruct subcarrier matrix of each symbiotic system and be specially as pre-stored: according to the frequency at each symbiotic system signal place, from described coefficient matrix P, extracting the row vector the efficiency of formation submatrix P of this frequency _s; According to the number of the shared bandwidth of symbiotic system signal and reconstruct subcarrier, from matrix P _smiddle extraction needs the column vector at frequency spectrum trap place, the efficiency of formation submatrix P _n; Use pseudo inverse matrix computational methods to calculate respectively the reconstruct subcarrier coefficient matrix-(P that adapts to each symbiotic system _n ^hp _n) ^-1p _n ^hp _s, and do pre-stored and process.

According to one embodiment of the method for the invention, further, describedly according to described reconstruct subcarrier matrix computations, go out reconstruct subcarrier sequence and described reconstruct subcarrier sequence inserted in the former data sequence of described ofdm system to be specially: determine the type of symbiotic system, draw symbiotic system signal center frequency and bandwidth; Read the reconstruct subcarrier coefficient matrix that is applicable to described symbiotic system; According to the centre frequency of symbiotic system, the data zero setting by this frequency place protection bandwidth, forms reconstruct QPSK data sequence; Reconstruct subcarrier coefficient matrix and reconstruct QPSK data sequence are done to complex vector located multiplication, obtain reconstruct subcarrier sequence; Reconstruct subcarrier sequence is turned back to former QPSK symbol sebolic addressing.

According to one embodiment of the method for the invention, further, reconstruct subcarrier number is 2,3 or 4; M is 4,5,6,7 or 8.

According to one embodiment of the method for the invention, further, described symbiotic system is WiMax system, and centre frequency is 3407MHz, and bandwidth is 14MHz.

The technical problem that the present invention will solve is to provide a kind of frequency spectrum processing device for ofdm system, by inserting reconstruct subcarrier data, forms OFDM spectral notch, avoids mutually disturbing with symbiotic system.

A kind of frequency spectrum processing device for ofdm system, comprise: matrix of frequency coefficients computing unit, for calculating ofdm system and symbiotic system at the coefficient matrix at frequency overlap place, according to described coefficient matrix, obtain in described ofdm system other subcarrier secondary lobe in the power influences at frequency place that coexists; Subcarrier computing unit, for obtaining the reconstruct subcarrier matrix corresponding to each symbiotic system, and makes pre-stored; According to reconstruct subcarrier matrix computations, go out reconstruct subcarrier sequence; Carrier wave reconfiguration unit, for described reconstruct subcarrier sequence being inserted to the former data sequence of described ofdm system, forms trap.

According to device of the present invention embodiment, further, described matrix of frequency coefficients computing unit, according to the characteristics of signals of symbiotic system, is selected the sampling multiple M of signal and the number of reconstruct subcarrier; Described matrix of frequency coefficients computing unit carries out M sampling to described ofdm system signal, obtains ofdm signal frequency spectrum, and described frequency spectrum is:

$Y\left(l\right)=\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)\exp (-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA00001938383700031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{n}{N}\frac{l}{M});$

Wherein, N represents ofdm system subcarrier number, and x (n) is QPSK mapping symbols, and l is total number of sample points; Described matrix of frequency coefficients computing unit draws the coefficient matrix P of ofdm signal according to described frequency spectrum; The matrix that described coefficient matrix P is MN * N, each element in described coefficient matrix P is:

$p(l,k)={\mathrm{\&Sigma;}}_{n=0}^{N-1}\exp \left(\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA00001938383700031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{n}{N}(k-\frac{l}{M})\right).$

According to device of the present invention embodiment, further, described subcarrier computing unit, according to the frequency at each symbiotic system signal place, extracts the row vector the efficiency of formation submatrix P of this frequency from described coefficient matrix P _s; Described subcarrier computing unit is according to the number of the shared bandwidth of symbiotic system signal and described reconstruct subcarrier, from matrix P _smiddle extraction needs the column vector at frequency spectrum trap place, the efficiency of formation submatrix P _n; Described subcarrier computing unit is used pseudo inverse matrix computational methods to calculate respectively the reconstruct subcarrier coefficient matrix-(P that adapts to each symbiotic system _n ^hp _n) ^-1p _n ^hp _s, and do pre-stored and process.

According to device of the present invention embodiment, further, described subcarrier computing unit is determined the type of symbiotic system, draws symbiotic system signal center frequency and bandwidth; Described subcarrier computing unit reads the reconstruct subcarrier coefficient matrix that is applicable to symbiotic system; According to the centre frequency of symbiotic system, the data zero setting by this frequency place protection bandwidth, forms reconstruct QPSK data sequence; Described subcarrier computing unit is done complex vector located multiplication by reconstruct subcarrier coefficient matrix and reconstruct QPSK data sequence, obtains reconstruct subcarrier sequence; Carrier wave reconfiguration unit turns back to former QPSK symbol sebolic addressing by reconstruct subcarrier sequence.

A kind of frequency spectrum coexistence method for ofdm system of the present invention and frequency spectrum processing device, by inserting reconstruct subcarrier data, form OFDM spectral notch, offset other subcarrier secondary lobe power, reduced the complexity that system realizes, and avoided mutually disturbing with symbiotic system.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skills, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.

Fig. 1 is according to the flow chart of an embodiment of the frequency spectrum coexistence method for ofdm system of the present invention;

Fig. 2 is according to the flow chart of another embodiment of the frequency spectrum coexistence method for ofdm system of the present invention;

Fig. 3 for inserting the schematic diagram of an embodiment of reconstruct subcarrier in an OFDM symbol;

Fig. 4 is according to the schematic diagram of an embodiment of the frequency spectrum processing device for ofdm system of the present invention.

Embodiment

With reference to the accompanying drawings the present invention is described more fully, exemplary embodiment of the present invention is wherein described.Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills, not making all other embodiment that obtain under creative work prerequisite, belong to the scope of protection of the invention.Below in conjunction with each figure and embodiment, technical scheme of the present invention is carried out to many-sided description.

Fig. 1 is according to the flow chart of an embodiment of the frequency spectrum coexistence method for ofdm system of the present invention.As shown in Figure 1: the frequency spectrum coexistence method for ofdm system comprises:

Step 102, calculates ofdm system and symbiotic system at the coefficient matrix at frequency overlap place, according to coefficient matrix, obtains in ofdm system other subcarrier secondary lobe in the power influences at frequency place that coexists.

Step 103, obtains the reconstruct subcarrier matrix corresponding to each symbiotic system, and makes pre-stored.

Step 104, according to reconstruct subcarrier matrix computations reconstruct subcarrier sequence, and inserts reconstruct subcarrier sequence in the former data sequence of ofdm system, forms trap.

According to one embodiment of present invention, according to the characteristics of signals of symbiotic system, select the sampling multiple M of signal and the number of reconstruct subcarrier; Ofdm system signal is carried out to M sampling, obtain ofdm signal frequency spectrum, frequency spectrum is:

$Y\left(l\right)=\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)\exp (-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA00001938383700031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{n}{N}\frac{l}{M});$

Wherein, N represents ofdm system subcarrier number, and x (n) is QPSK mapping symbols, and l is total number of sample points; According to frequency spectrum, draw the coefficient matrix P of ofdm signal; Coefficient matrix P is the matrix of MN * N, and each element in coefficient matrix P is:

$p(l,k)={\mathrm{\&Sigma;}}_{n=0}^{N-1}\exp \left(\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA00001938383700031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{n}{N}(k-\frac{l}{M})\right).$

According to one embodiment of present invention, according to the frequency at each symbiotic system signal place, from coefficient matrix P, extract the row vector the efficiency of formation submatrix P of this frequency _s; According to the number of the shared bandwidth of symbiotic system signal and reconstruct subcarrier, from matrix P _smiddle extraction needs the column vector at frequency spectrum trap place, the efficiency of formation submatrix P _n; Use pseudo inverse matrix computational methods to calculate respectively the reconstruct subcarrier coefficient matrix-(P that adapts to each symbiotic system _n ^hp _n) ^-1P _n ^hp _s, and do pre-stored and process.

Determine the type of symbiotic system, draw symbiotic system signal center frequency and bandwidth; Read the reconstruct subcarrier coefficient matrix that is applicable to symbiotic system; According to the centre frequency of symbiotic system, by the data zero setting in this frequency place protection bandwidth, form reconstruct QPSK(Quadrature Phase Shift Keying: Quadrature Phase Shift Keying) data sequence; Reconstruct subcarrier coefficient matrix and reconstruct QPSK data sequence are done to complex vector located multiplication, obtain reconstruct subcarrier sequence; Reconstruct subcarrier sequence is turned back to former QPSK symbol sebolic addressing.

Fig. 2 is according to the flow chart of another embodiment of the frequency spectrum coexistence method for ofdm system of the present invention.By calculating coefficient matrix with symbiotic system frequency overlap place, obtain in ofdm system other subcarrier secondary lobe in the power influences at frequency place that coexists; according to the signal bandwidth characteristics design of symbiotic system, offset subcarrier sequence; can put the impact that other OFDM subcarrier secondary lobe is offset on empty basis at subcarrier data, deepen the protection degree of depth of spectral notch.According to the coefficient matrix of the reconstruct subcarrier of different symbiotic system precomputations storage, according to symbiotic system result of determination dynamic calculation, show that reconstruct subcarrier inserts OFDM transmission data sequence, to play, offset other subcarrier secondary lobe power, reduced the complexity that system realizes.

Method of the present invention draws according to the sampling coefficient matrix of system signal the factor that affects frequency spectrum notch depth, designs and inserts reconstruct subcarrier sequence to deepen protection notch depth, and use preliminary treatment to reduce system implementation complexity.As shown in Figure 2, the frequency spectrum coexistence method for ofdm system comprises the following steps:

Step 201, selects the sampling multiple M of signal and the number of intron carrier wave for the characteristics of signals of the system coexisting.According to an embodiment, M ∈ [4,8], as symbiotic system needs the darker trap protection degree of depth, can suitably adjust the numerical value of M.Insert the new subcarrier number of reconstruct between 2 to 4.

Step 202, carries out M sampling to ofdm system signal, obtains ofdm signal frequency spectrum, and according to frequency spectrum, its mathematic(al) representation is:

$Y\left(l\right)=\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)\exp (-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA00001938383700031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{n}{N}\frac{l}{M}).$

Wherein N represents ofdm system subcarrier number, and x (n) is QPSK mapping symbols, and l is total number of sample points.According to frequency spectrum, obtain, the coefficient matrix P of ofdm signal, P is the matrix of MN * N size, each element of matrix is:

$p(l,k)={\mathrm{\&Sigma;}}_{n=0}^{N-1}\exp \left(\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA00001938383700031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{n}{N}(k-\frac{l}{M})\right).$

Step 203 according to the frequency at symbiotic system signal place, extracts the row vector the efficiency of formation submatrix P of this frequency from coefficient matrix P _s.

Step 204, according to the number of the shared bandwidth of symbiotic system signal and insertion reconstruct subcarrier, from matrix P _smiddle extraction needs the column vector the efficiency of formation submatrix P at frequency spectrum trap place _n.

Step 205, is used pseudo inverse matrix computational methods to calculate respectively the reconstruct subcarrier coefficient matrix-(P that adapts to each symbiotic system _n ^hp _n) ^-1p _n ^hp _s.

Step 206, does pre-stored and processes.

Step 207, determines the type of symbiotic system according to frequency spectrum perception,

Step 208, draws symbiotic system signal center frequency and bandwidth.According to an embodiment, current symbiotic system is WiMax system, and centre frequency is 3407MHz, and bandwidth is 14MHz.

Step 209, is used selector switch to read the reconstruct subcarrier coefficient matrix that is applicable to symbiotic system automatically.

Step 210, according to the centre frequency of symbiotic system, the data zero setting by this frequency place protection bandwidth, forms reconstruct QPSK data sequence.

Step 211, does complex vector located multiplication by reconstruct subcarrier coefficient matrix and reconstruct QPSK data sequence, obtains reconstruct subcarrier sequence.

Step 212, turns back to former QPSK symbol sebolic addressing by reconstruct subcarrier sequence, to play, offsets other subcarrier secondary lobe power, deepens trap, the object of protection symbiotic system.

By ofdm signal spectral sample is obtained to coefficient matrix, can calculate in the frequency range that need to form trap the residual power impact on other subcarrier after data zero setting in this region.Design on this basis new reconstruct subcarrier and insert, with reconstruct sub-carrier power, offset other subcarrier in impact, reach the effect of deepening trap.

Through algorithm development, coefficient submatrix P _nin element only relevant with sampling multiple M with the subcarrier number of interference place, at sampling multiple M and the number of inserting reconstruct subcarrier, determine in situation coefficient submatrix P _nvalue relevant with the carrier wave number being disturbed, and irrelevant with the carrier position being disturbed.Therefore can to pseudo inverse matrix, invert in advance-(P _n ^hp _n) ^-1p _n ^hpreliminary treatment is done in computing.

Ofdm system and known wireless communication system coexist, and centre frequency and the bandwidth of this wireless telecommunication system signal are known parameters.Determining by frequency spectrum perception after the symbiotic system being disturbed, can draw the frequency range that needs spectral notch, then can Coefficient of determination submatrix P _s, so reconstruct subcarrier coefficient matrix-(P _n ^hp _n) ^-1p _n ^hp _scan and store standby according to the characteristics of signals preliminary treatment of different symbiotic systems.

According to one embodiment of present invention, former ofdm system QPSK subcarrier data sequence is X=[X (0) ... X (N)] ^t, wherein N is ofdm system total number of sub-carriers, according to the centre frequency of symbiotic system, judgement disturbs position and ofdm system (a, b) work song carrier wave to overlap, will [X (a-2) ... X (N-b+2)] ^tthe zero setting of QPSK modulating data, form reconstruct QPSK data sequence g; By reconstruct subcarrier coefficient matrix-(P _n ^hp _n) ^-1p _n ^hp _sg does complex vector located multiplication with reconstruct QPSK data sequence, obtains reconstruct subcarrier sequences h, h=-(P _n ^hp _n) ^-1p _n ^hp _sg.Reconstruct subcarrier sequences h is turned back to former QPSK symbol sebolic addressing.

According to one embodiment of present invention, be given under a concrete OFDM configuration, the example of the practical application during with WiMax coexistence of systems, it should be noted that: the parameter in this example does not affect the generality of this patent.

If ofdm system significant character length N=128.First choose sampling multiple M=4, the sampling of frequency spectrum being done to 4 times obtains coefficient matrix P, the matrix that P is 512 * 128.For the WiMax system of centre frequency 3407MHz, its 14MHz signal bandwidth can form trap protection by 3 OFDM subcarriers and 2 reconstruct subcarriers, extracts coefficient submatrix P from coefficient matrix P _sand P _n, P wherein _sbe 9 * 128 matrixes, P _nbe 9 * 5 matrixes, calculate reconstruct subcarrier coefficient matrices A, the matrix that A is 5 * 128, carries out pre-stored processing to A.

The WiMax system that coexists detected in real time, by needing the data zero setting at trap frequency place in former QPSK sequence, form 128 * 1 sequence g.Read reconstruct subcarrier coefficient matrices A, calculate h=A * g, h is 5 * 1 reconstruct subcarrier sequence.H is inserted into former QPSK and need falls into wave frequency place, complete the trap protection to WiMax system, reach coexistence of systems effect.

Fig. 3 for inserting the schematic diagram of an embodiment of reconstruct subcarrier in an OFDM symbol.The reconstruct subcarrier that 1 representative is inserted; 2 represent that subcarrier data is not by the region of zero setting; 3 represent the region of subcarrier data zero setting, need to form the frequency range of trap protection symbiotic system.

Fig. 4 is the frequency spectrum processing device 41 for ofdm system according to the schematic diagram of an embodiment of the frequency spectrum processing device for ofdm system of the present invention, comprising: matrix of frequency coefficients computing unit 411, subcarrier computing unit 412 and carrier wave reconfiguration unit 413.Matrix of frequency coefficients computing unit 411 calculates ofdm systems and symbiotic system at the coefficient matrix at frequency overlap place, according to coefficient matrix, obtains in ofdm system other subcarrier secondary lobe in the power influences at frequency place that coexists.Subcarrier computing unit 412 obtains the reconstruct subcarrier matrix corresponding to each symbiotic system, and makes pre-stored.According to reconstruct subcarrier matrix computations, go out reconstruct subcarrier sequence.Carrier wave reconfiguration unit 413 inserts reconstruct subcarrier sequence in the former data sequence of ofdm system, forms trap.

According to one embodiment of present invention, matrix of frequency coefficients computing unit 411, according to the characteristics of signals of symbiotic system, is selected the sampling multiple M of signal and the number of reconstruct subcarrier; 411 pairs of ofdm system signals of matrix of frequency coefficients computing unit carry out M sampling, obtain ofdm signal frequency spectrum, and frequency spectrum is:

$Y\left(l\right)=\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)\exp (-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA00001938383700031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{n}{N}\frac{l}{M});$

Wherein, N represents ofdm system subcarrier number, and x (n) is QPSK mapping symbols, and l is total number of sample points; Matrix of frequency coefficients computing unit 411 draws the coefficient matrix P of ofdm signal according to frequency spectrum; Coefficient matrix P is the matrix of MN * N, and each element in coefficient matrix P is:

$p(l,k)={\mathrm{\&Sigma;}}_{n=0}^{N-1}\exp \left(\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA00001938383700031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\frac{n}{N}(k-\frac{l}{M})\right).$

According to one embodiment of present invention, subcarrier computing unit 412, according to the frequency at each symbiotic system signal place, extracts the row vector the efficiency of formation submatrix P of this frequency from coefficient matrix P _s; Subcarrier computing unit 412 is according to the number of the shared bandwidth of symbiotic system signal and reconstruct subcarrier, from matrix P _smiddle extraction needs the column vector at frequency spectrum trap place, the efficiency of formation submatrix P _n; Subcarrier computing unit 412 is used pseudo inverse matrix computational methods to calculate respectively the reconstruct subcarrier coefficient matrix-(P that adapts to each symbiotic system _n ^hp _n) ^-1p _n ^hp _s, and do pre-stored and process.

According to one embodiment of present invention, subcarrier computing unit 412 is determined the type of symbiotic system, draws symbiotic system signal center frequency and bandwidth; Subcarrier computing unit 412 reads the reconstruct subcarrier coefficient matrix that is applicable to symbiotic system; According to the centre frequency of symbiotic system, the data zero setting by this frequency place protection bandwidth, forms reconstruct QPSK data sequence; Subcarrier computing unit 412 is done complex vector located multiplication by reconstruct subcarrier coefficient matrix and reconstruct QPSK data sequence, obtains reconstruct subcarrier sequence; Carrier wave reconfiguration unit 413 turns back to former QPSK symbol sebolic addressing by reconstruct subcarrier sequence.

Method and apparatus of the present invention is according to the protection requirement of symbiotic system; ofdm system signal is carried out to the sampling of specified multiple; obtain the coefficient matrix of signal; extract the matrix row, column with symbiotic system frequency overlap place; form interference coefficient matrix, according to coefficient matrix, calculate the power influences value of all the other subcarrier secondary lobes to this place.The power influences value drawing according to calculating interference coefficient matrix redesigns subcarrier data sequence, makes sequence can offset the power influences of other subcarrier secondary lobe.According to symbiotic system characteristics of signals, to being applicable to the reconstruct subcarrier coefficient matrix of different system, carry out precomputation and pre-stored.According to symbiotic system result of determination; use selector switch to call dynamically the reconstruct subcarrier coefficient matrix computing reconstruct subcarrier of pre-stored, and be inserted in OFDM transmission data sequence, to play, offset other subcarrier secondary lobe power; deepen trap, the object of protection symbiotic system.

May realize in many ways method and system of the present invention.For example, can realize method and system of the present invention by any combination of software, hardware, firmware or software, hardware, firmware.The said sequence that is used for the step of method is only in order to describe, and the step of method of the present invention is not limited to above specifically described order, unless otherwise specified.In addition, in certain embodiments, can be also the program being recorded in recording medium by the invention process, these programs comprise for realizing the machine readable instructions of the method according to this invention.Thereby the present invention also covers storage for carrying out the recording medium of the program of the method according to this invention.

Description of the invention provides for example with for the purpose of describing, and is not exhaustively or limit the invention to disclosed form.Many modifications and variations are obvious for the ordinary skill in the art.Selecting and describing embodiment is for better explanation principle of the present invention and practical application, thereby and makes those of ordinary skill in the art can understand the various embodiment with various modifications that the present invention's design is suitable for special-purpose.

Claims (10)

1. for a frequency spectrum coexistence method for ofdm system, it is characterized in that:

Calculate ofdm system and symbiotic system at the coefficient matrix at frequency overlap place, according to described coefficient matrix, obtain in described ofdm system other subcarrier secondary lobe in the power influences at frequency place that coexists;

Obtain the reconstruct subcarrier matrix corresponding to each symbiotic system, and make pre-stored;

According to described reconstruct subcarrier matrix computations reconstruct subcarrier sequence, and described reconstruct subcarrier sequence is inserted in the former data sequence of described ofdm system, formed trap.

2. method as claimed in claim 2, is characterized in that, described calculating ofdm system and the coefficient matrix of symbiotic system at frequency overlap place are specially:

According to the characteristics of signals of symbiotic system, select the sampling multiple M of signal and the number of reconstruct subcarrier;

Described ofdm system signal is carried out to M sampling, obtain ofdm signal frequency spectrum, described frequency spectrum is:

$Y\left(l\right)=\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)\exp (-j2\mathrm{\&pi;}\frac{n}{N}\frac{l}{M});$

Wherein, N represents ofdm system subcarrier number, and x (n) is QPSK mapping symbols, and l is total number of sample points;

According to described frequency spectrum, draw the coefficient matrix P of ofdm signal; The matrix that described coefficient matrix P is MN * N, each element in described coefficient matrix P is:

$p(l,k)={\mathrm{\&Sigma;}}_{n=0}^{N-1}\exp \left(j2\mathrm{\&pi;}\frac{n}{N}(k-\frac{l}{M})\right).$

3. method as claimed in claim 2, is characterized in that, described in obtain corresponding to the reconstruct subcarrier matrix of each symbiotic system and be specially as pre-stored:

According to the frequency at each symbiotic system signal place, from described coefficient matrix P, extract the row vector the efficiency of formation submatrix P of this frequency _s;

According to the number of the shared bandwidth of symbiotic system signal and reconstruct subcarrier, from matrix P _smiddle extraction needs the column vector at frequency spectrum trap place, the efficiency of formation submatrix P _n;

Use pseudo inverse matrix computational methods to calculate respectively the reconstruct subcarrier coefficient matrix-(P that adapts to each symbiotic system _n ^hp _n) ^-1p _n ^hp _s, and do pre-stored and process.

4. method as claimed in claim 3, is characterized in that, describedly according to described reconstruct subcarrier matrix computations, goes out reconstruct subcarrier sequence and described reconstruct subcarrier sequence is inserted in the former data sequence of described ofdm system to be specially:

Determine the type of symbiotic system, draw symbiotic system signal center frequency and bandwidth;

Read the reconstruct subcarrier coefficient matrix that is applicable to described symbiotic system; According to the centre frequency of symbiotic system, the data zero setting by this frequency place protection bandwidth, forms reconstruct QPSK data sequence;

Reconstruct subcarrier coefficient matrix and reconstruct QPSK data sequence are done to complex vector located multiplication, obtain reconstruct subcarrier sequence;

Reconstruct subcarrier sequence is turned back to former QPSK symbol sebolic addressing.

5. method as claimed in claim 2, is characterized in that:

Reconstruct subcarrier number is 2,3 or 4; M is 4,5,6,7 or 8.

6. method as claimed in claim 4, is characterized in that:

Described symbiotic system is WiMax system, and centre frequency is 3407MHz, and bandwidth is 14MHz.

7. for a frequency spectrum processing device for ofdm system, it is characterized in that:

Matrix of frequency coefficients computing unit, for calculating ofdm system and symbiotic system at the coefficient matrix at frequency overlap place, obtains in described ofdm system other subcarrier secondary lobe in the power influences at frequency place that coexists according to described coefficient matrix;

Subcarrier computing unit, for obtaining the reconstruct subcarrier matrix corresponding to each symbiotic system, and makes pre-stored; According to reconstruct subcarrier matrix computations, go out reconstruct subcarrier sequence;

Carrier wave reconfiguration unit, for described reconstruct subcarrier sequence being inserted to the former data sequence of described ofdm system, forms trap.

8. device as claimed in claim 7, is characterized in that:

Described matrix of frequency coefficients computing unit, according to the characteristics of signals of symbiotic system, is selected the sampling multiple M of signal and the number of reconstruct subcarrier;

Described matrix of frequency coefficients computing unit carries out M sampling to described ofdm system signal, obtains ofdm signal frequency spectrum, and described frequency spectrum is:

$Y\left(l\right)=\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}x\left(n\right)\exp (-j2\mathrm{\&pi;}\frac{n}{N}\frac{l}{M});$

Wherein, N represents ofdm system subcarrier number, and x (n) is QPSK mapping symbols, and l is total number of sample points;

Described matrix of frequency coefficients computing unit draws the coefficient matrix P of ofdm signal according to described frequency spectrum; The matrix that described coefficient matrix P is MN * N, each element in described coefficient matrix P is:

$p(l,k)={\mathrm{\&Sigma;}}_{n=0}^{N-1}\exp \left(j2\mathrm{\&pi;}\frac{n}{N}(k-\frac{l}{M})\right).$

9. device as claimed in claim 8, is characterized in that:

Described subcarrier computing unit, according to the frequency at each symbiotic system signal place, extracts the row vector the efficiency of formation submatrix P of this frequency from described coefficient matrix P _s;

Described subcarrier computing unit is according to the number of the shared bandwidth of symbiotic system signal and described reconstruct subcarrier, from matrix P _smiddle extraction needs the column vector at frequency spectrum trap place, the efficiency of formation submatrix P _n;

Described subcarrier computing unit is used pseudo inverse matrix computational methods to calculate respectively the reconstruct subcarrier coefficient matrix-(P that adapts to each symbiotic system _n ^hp _n) ^-1p _n ^hp _s, and do pre-stored and process.

10. device as claimed in claim 9, is characterized in that:

Described subcarrier computing unit is determined the type of symbiotic system, draws symbiotic system signal center frequency and bandwidth;

Described subcarrier computing unit reads the reconstruct subcarrier coefficient matrix that is applicable to symbiotic system; According to the centre frequency of symbiotic system, the data zero setting by this frequency place protection bandwidth, forms reconstruct QPSK data sequence;

Described subcarrier computing unit is done complex vector located multiplication by reconstruct subcarrier coefficient matrix and reconstruct QPSK data sequence, obtains reconstruct subcarrier sequence;

Carrier wave reconfiguration unit turns back to former QPSK symbol sebolic addressing by reconstruct subcarrier sequence.

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