CN101374041B - Compatible system containing multi-OFDM of different districts and frequency spectrum sharing method - Google Patents

Abstract

The invention discloses a compatible system comprising multiple orthogonal frequency division multiplexing (OFDM) systems in different subzones and a frequency spectrum sharing method, which can prevent the mutual interference between the systems and ensure normal operations of the systems. The compatible system comprises a main OFDM system in a first subzone (hereinafter referred to as main system) and a secondary OFDM system in a second subzone adjacent to the first subzone (hereinafter referred to as secondary system), wherein the frequency band of the secondary system is located in the frequency band of the main system and the subcarrier distances of the main system and the secondary system are the same. The secondary system in the second subzone transmits the data via the useful subcarriers within the frequency band of the secondary system and the protective subcarrier signal powers on both sides is adjusted to zero. One or more the useful subcarriers that are adjacent to the frequency band of the second system is configured into an offset subcarrier by the main system in the first subzone, and the signal is transmitted via the offset subcarriers. The amplitude and the symbol of the signal are configured to allow the signal to eliminate the interference of the useful subcarriers outside the frequency band of the second system on the useful subcarriers of the second system.

Description

The compatible system and the frequency spectrum sharing method that comprise multi-OFDM in the different districts

Technical field

The present invention relates to digital communicating field; Particularly relate to a kind of based on OFDM (Orthogonal Frequency Division Multiplex, OFDM) method of two kinds of bandwidth wireless communication systems frequency spectrums of technology coexistence and be included in the compatible system of the multiple ofdm system in the different districts.

Background technology

As a kind of multi-carrier transmission pattern; OFDM converts one group of low-speed parallel data flow transmitted into through the data flow with a high-speed transfer; System is reduced the susceptibility of multidiameter fading channel frequency selectivity greatly; And the introducing of Cyclic Prefix has further strengthened the anti-intersymbol interference of system (Inter-symbol Interference, ability ISI) again; Characteristics such as bandwidth availability ratio in addition is high, realization is simple make OFDM more and more wider in the application in radio communication basin; Such as, wlan system, all be based on the system of OFDM technology based on the WiMax system of orthogonal frequency division multiplexing multiple access and mobile radio system of future generation (4G system) etc.

The 4G wireless communication system has higher spectrum efficiency than 3-G (Generation Three mobile communication system), and the target of 4G system is to make the mobile user data transmission rate reach 100Mbit/s before 2010, and the stationary user message transmission rate reaches 1Gbit/s.Because the needs of GSM smooth evolution, in order to protect benefits of operators, in the regular hour, the 4th generation communication system will be compatible with 3-G (Generation Three mobile communication system) (like TD-SCDMA system or 802.16E system etc.) or coexist.

The bandwidth of 4G wireless communication system can be up to 100MHz, and adaptive-bandwidth so that the 4G system whole-network is provided with the system bandwidth of each sub-district flexibly according to business demand, covers and the focus covering to realize Da Qu simultaneously.

The scene of above-mentioned two kinds of situations is established sub-district 1 and is belonged to down town, hot spot coverage shown in Fig. 1 a, adopts bigger system bandwidth; Like 80-100MHz, shown in the w1 of Fig. 1 b, and sub-district 2 is professional less with sub-district 3; So; Adopt less system bandwidth, like 20MHz, shown in the w2 of Fig. 1 b.

For the 4th generation communication system and the compatible situation of 3-G (Generation Three mobile communication system); Like 802.16m and 16e system; Bandwidth is that the partial-band (like bandwidth w2) of the 16m system of w1 is used to support the 16e system in the sub-district 1, and two 16m of system and 16e are promptly arranged in the sub-district 1, and its frequency band and sub-carrier configuration are shown in Fig. 3 a; The 16m system bandwidth is w1, and the 16e system uses the partial-band of the middle bandwidth of 16m system as w2.It is the system of the 16e of w2 that bandwidth is adopted with 3 of sub-districts in sub-district 2.When the system parameters of two systems was identical, like ofdm system subcarrier spacing, subframe lengths etc., the frequency spectrum of two systems co-existed in the mode of sharing with the OFDM subcarrier in the sub-district 1, to realize the high availability of frequency spectrum.

For the situation that Da Qu covers and focus covering frequency spectrum coexists; If the partial-band of the w1 bandwidth of sub-district 1 supports Da Qu to cover (bandwidth is w2) simultaneously and focus covers (bandwidth is w1); It is the Da Qu covering system of w2 that bandwidth is then still adopted with sub-district 3 in sub-district 2, and the system parameters of two system's employings is identical, like ofdm system subcarrier spacing, subframe lengths etc.; Then two the frequency spectrum coexistences of system in sub-district 1 are also with the shared modes of OFDM subcarrier, to realize the high availability of frequency spectrum.

It may be noted that in above-mentioned two kinds of situations that in sub-district 1, two kinds of ofdm systems adopt the shared mode of subcarrier to realize the frequency spectrum coexistence, owing to be quadrature between the OFDM subcarrier, so disturbing can not appear in two systems.But in the sub-district 1 with the different system (like 16m system and 16e system) of sub-district 2 (or sub-district 3) because quadrature no longer between subcarrier, so, be arranged in the working band that frequency spectrum w1-w2 signal partly will leak into sub-district 2 (or sub-district 3) w2 in the sub-district 1.

The problem that above-mentioned scene need solve is; Near the intersection of the sub-district of different bandwidth; The interference of big bandwidth cell to little bandwidth cell can appear; In order to realize that the 4G system whole-network is provided with the needs of the system bandwidth of each sub-district flexibly according to business demand, must solve disturbing between two systems so challenging problem.

Summary of the invention

The technical issues that need to address of the present invention provide a kind of compatible system and frequency spectrum sharing method that comprises multi-OFDM in the different districts, can guarantee not disturb operate as normal between the system mutually.

In order to solve the problems of the technologies described above; The invention provides in a kind of different districts the frequency spectrum sharing method when using multiple ofdm system; Ofdm system in first sub-district is a main system, and the ofdm system in the second adjacent sub-district is a subsystem, and wherein the frequency band of subsystem is within the frequency band of main system; And main system is identical with the subcarrier spacing of subsystem, wherein:

Send data on the useful subcarrier of the subsystem of said second sub-district in its frequency band, with the protection sub-carrier signal power zero setting of both sides;

The main system of said first sub-district will be adjacent with said subsystem frequency band one or more useful sub-carrier configuration for offsetting subcarrier; On said counteracting subcarrier, transmit, its amplitude and symbol should make this signal cancellation main system in the interference of out-of-band other the useful subcarrier of subsystem to the useful subcarrier generation of said subsystem.

Further; Said method also can have following characteristics; Also there is a said subsystem in said first sub-district; All the subsystem with second sub-district is identical with sub-carrier configuration, data receiver formula for the frequency band of this subsystem, and said main system is with all the useful subcarrier signals transmitting power zero setting on the inherent said subsystem frequency band of its frequency band.

Further; Said method also can have following characteristics; Said first sub-district has only a main system; This main system disposes with subcarrier, protection subcarrier and transmission data by the identical mode of said subsystem in the frequency band identical with said subsystem, and what wherein send on the useful subcarrier in this frequency band is the data of main system.

Further; Said method also can have following characteristics; When configuration; The left margin of the useful subcarrier in the left margin of the useful subcarrier in the said subsystem frequency band and the said main system frequency band is alignd, and perhaps the right margin with the useful subcarrier in the right margin of the useful subcarrier in the said subsystem frequency band and the said main system frequency band aligns.

Further; Said method also can have following characteristics, and the signal that said counteracting subcarrier sends is confirmed according to the following steps: at first from main system, choose several as the weighting subcarrier in the useful subcarrier of the transmission main system data adjacent with said counteracting subcarrier; According to the amplitude and the symbol of said weighting subcarrier,, confirm the amplitude and the symbol of said counteracting subcarrier then according to offsetting of the requirement of said weighting subcarrier to useful subcarrier interference in the said subsystem frequency band.

Further, said method also can have following characteristics, and the signal that said counteracting subcarrier sends is further confirmed by following method: establishing L amplitude vector of offsetting subcarrier is G _L: G _L=[g ₁, g ₂..., g _L] ^T, the amplitude vector of establishing m weighting subcarrier is A _m: A _m=[a ₁, a ₂..., a _m] ^T, wherein, the transposition of T representing matrix; Choosing the range signal of offsetting subcarrier is the weighted sum of weighting subcarrier amplitude: G _L=C * A _m, wherein, C is L * m weighting matrix: C=[c _Lm] _{L * m}, said c _Lm, L and m calculate through optimization algorithm, makes that promptly the monolateral band energy sum on said weighting subcarrier and the said counteracting subcarrier useful subcarrier frequency in the subsystem frequency band is minimum.

In order to solve the problems of the technologies described above, the present invention also provides a kind of compatible system that is included in the multiple ofdm system that adopts in the different districts, comprises the main ofdm system in first sub-district; Hereinafter to be referred as main system; And the inferior ofdm system in the second adjacent sub-district, hereinafter to be referred as subsystem, wherein the frequency band of subsystem is within the frequency band of main system; And main system is identical with the subcarrier spacing of subsystem, wherein:

Send data on the useful subcarrier of the subsystem of said second sub-district in its frequency band, with the protection sub-carrier signal power zero setting of both sides;

The main system of said first sub-district will be adjacent with said subsystem frequency band one or more useful sub-carrier configuration for offsetting subcarrier; On said counteracting subcarrier, transmit, its amplitude and symbol should make this signal cancellation main system in the interference of out-of-band other the useful subcarrier of subsystem to the useful subcarrier generation of said subsystem.

Further; Said system also can have following characteristics; Also there is a said subsystem in said first sub-district; All the subsystem with second sub-district is identical with sub-carrier configuration, data receiver formula for the frequency band of this subsystem, and said main system is with all the useful subcarrier signals transmitting power zero setting on the inherent said subsystem frequency band of its frequency band.

Further; Said system also can have following characteristics; Said first sub-district has only a main system; This main system disposes with subcarrier, protection subcarrier and transmission data by the identical mode of said subsystem in the frequency band identical with said subsystem, and what wherein send on the useful subcarrier in this frequency band is the data of main system.

Further; Said system also can have following characteristics; When configuration; The left margin of the useful subcarrier in the left margin of the useful subcarrier in the said subsystem frequency band and the said main system frequency band is alignd, and perhaps the right margin with the useful subcarrier in the right margin of the useful subcarrier in the said subsystem frequency band and the said main system frequency band aligns.

Further; Said system also can have following characteristics, and the signal that said counteracting subcarrier sends is confirmed according to the following steps: at first from main system, choose several as the weighting subcarrier in the useful subcarrier of the transmission main system data adjacent with said counteracting subcarrier; According to the amplitude and the symbol of said weighting subcarrier,, confirm the amplitude and the symbol of said counteracting subcarrier then according to offsetting of the requirement of said weighting subcarrier to useful subcarrier interference in the said subsystem frequency band.

Further, said system also can have following characteristics, and the signal that said counteracting subcarrier sends is further confirmed by following method: establishing L amplitude vector of offsetting subcarrier is G _L: G _L=[g ₁, g ₂..., g _L] ^T, the amplitude vector of establishing m weighting subcarrier is A _m: A _m=[a ₁, a ₂..., a _m] T, wherein, the transposition of T representing matrix; Choosing the range signal of offsetting subcarrier is the weighted sum of weighting subcarrier amplitude: G _L=C * A _m, wherein, C is L * m weighting matrix: C=[c _Lm] _{L * m}, said c _Lm, L and m calculate through optimization algorithm, makes that promptly the monolateral band energy sum on said weighting subcarrier and the said counteracting subcarrier useful subcarrier frequency in the subsystem frequency band is minimum.

The method of two kinds of bandwidth ofdm system frequency spectrums coexistence of the present invention, the part through main ofdm system subcarrier being divided into two non-overlapping copies (as the part of the w2 among Fig. 1 (b) with remove the remaining w1-w2 part in w2 part back), be used for the message transmission of system separately; Simultaneously; Through arranging of main ofdm system and time ofdm system protection subcarrier, realize frequency spectrum share main, inferior ofdm system, after the benefit that so is provided with is shared bandwidth; Main system may be controlled to the bandwidth that subsystem distributes; If the subsystem traffic carrying capacity increases, main system can distribute more bandwidth to adapt to professional needs for it, and vice versa.At last, offset subcarrier and weighting subcarrier, eliminate the interference between two systems through being provided with.Realize that simply, spectrum efficiency is high.

Description of drawings

Fig. 1 a is the sketch map of different bandwidth sub-district;

Fig. 1 b is the frequency spectrum share graph of a relation of different bandwidth sub-district;

Fig. 2 a and Fig. 2 b are respectively the master of different bandwidth, inferior ofdm system subcarrier sketch map;

Fig. 3 a is that the subcarrier of two system spectrum when sharing is provided with sketch map;

Fig. 3 b offsets subcarrier and the weighting subcarrier is provided with sketch map in the present embodiment;

Fig. 3 c is the sketch map that the useful subcarrier of subsystem aligns with the useful subcarrier right margin of main system among another embodiment of present embodiment.

Embodiment

OFDM (Orthogonal Frequency Division Multiplexing) is that orthogonal frequency division multiplexi is the high speed transmission technology under a kind of wireless environment.The frequency response curve of wireless channel is non-flat forms mostly, and the main thought of OFDM technology is divided into many orthogonal sub-channels with given channel exactly in frequency domain, on each subchannel, uses a number of sub-carrier to modulate, and each subcarrier parallel transmission.Like this, although total channel be non-flat forms, have frequency selectivity; But each subchannel is a relatively flat; What on each subchannel, carry out is narrow band transmission, and signal bandwidth is less than the respective bandwidth of channel, so the just interference between the erasure signal waveform greatly.Because the carrier wave of each subchannel is mutually orthogonal in ofdm system, so their frequency spectrum is overlapped, has so not only reduced the phase mutual interference between subcarrier, improved the availability of frequency spectrum simultaneously again.

The OFDM modulation can realize given channel is divided into many orthogonal sub-carriers through FFT, and its expression formula is:

$x_N\left(m\right)=\frac{1}{\sqrt{N}}\underset{i=0}{\overset{N-1}{\mathrm{\Σ}}}{s\left(i\right)e}^{j(2\mathrm{\π}/N)\mathrm{im}}---\left(1\right)$

Wherein, N is a sub-carrier number, also is counting of FFT conversion; S (i) is that binary data carries out the data symbol after the digital modulation on the i number of sub-carrier; x _N(m) be the signal after the modulation.

Application scenarios is following: when having moved two ofdm systems in the sub-district and share frequency spectrum, the bandwidth of establishing an ofdm system is w1, is called main ofdm system, and the bandwidth of another ofdm system is w2, is called time ofdm system, wherein, and w ₂＜w ₁The frequency band that is subsystem is within the frequency band of main system.Two ofdm system frequency spectrum shared bandwidth are w1.Main system is identical with the subcarrier spacing of subsystem, is Δ f.Wherein, the total number of sub-carriers that main ofdm system is set is N ₁, comprising protection subcarrier and useful subcarrier, the protection subcarrier is positioned at the both sides of main ofdm system frequency band, and the subcarrier number is respectively N _GL1And N _GR1, useful subcarrier is positioned at the centre of frequency band, and the subcarrier number is N _Used1, the frequency of minimum useful subcarrier is f ₁₁, the frequency of maximum useful subcarrier is f ₁₂, shown in Fig. 2 a.The total number of sub-carriers that time ofdm system is set is N ₂, comprising protection subcarrier and useful subcarrier, the protection subcarrier is positioned at the both sides of time ofdm system frequency band, and the subcarrier number is respectively N _GL2And N _GR2, useful subcarrier is positioned at the centre of frequency band, and the subcarrier number is N _Used2, the frequency of minimum useful subcarrier is f ₂₁, the frequency of maximum useful subcarrier is f ₂₂, shown in Fig. 2 b.

Main ofdm system occupied bandwidth is shown in Fig. 3 a the first half, and main ofdm system is provided with according to the standard of bandwidth series under it and uses subcarrier N _Used1, protection subcarrier N _GL1And N _GR1, and the place's signal zero setting of protection subcarrier.The mode that inferior ofdm system and main ofdm system adopt subcarrier to share is shared the frequency band of main system; Wherein time ofdm system takies the part of the useful subcarrier of main ofdm system; The unappropriated useful subcarrier of main ofdm system is used to modulate the information of main system, and two systems are used for the subcarrier non-overlapping copies of modulating data.(still stipulate by the respective standard of this system by the useful subcarrier of noting main system in the literary composition with all the useful subcarriers on said subsystem frequency band in its frequency band for main system; Even be not called useful subcarrier because of frequency spectrum share does not transmit yet) signal power zero setting, shown in Fig. 3 a.Send data on the useful subcarrier of subsystem in its frequency band, and with the protection sub-carrier signal zero setting of both sides.

The minimum useful sub-carrier frequencies of choosing main ofdm system is identical with the frequency of the minimum useful subcarrier of time ofdm system, the monolateral alignment in promptly useful subcarrier border, for example f ₂₁=f ₁₁, shown in Fig. 3 a, the sub-carrier number that inferior ofdm system takies is: N _Used2+ N _GL2+ N _GR2, promptly time ofdm system is provided with according to the standard of bandwidth series under it and uses subcarrier N _Used2, protection subcarrier N _GL2And N _GR2, wherein protect the signal zero setting of subcarrier place.Main system with the useful subcarrier of subsystem lap on the power zero setting that transmits, the frequency band of main system and sub-carrier configuration are seen the first half of Fig. 3 a, the frequency band of subsystem and sub-carrier configuration are seen the latter half of Fig. 3 a.

Subsystem in the frequency band of the subsystem that in another sub-district adjacent with above-mentioned sub-district, moves, sub-carrier configuration, data receiver formula and above-mentioned first sub-district is identical.The left margin that useful subcarrier in the neighbor cell subsystem frequency band is set and the useful subcarrier border in the first sub-district main system frequency band be monolateral aligns and does not disturb with inferior ofdm system that the guarantees neighbor cell main ofdm system to first sub-district, and the while, useful subcarrier utilance was the highest.

Some useful subcarriers that the main system of first sub-district is adjacent with the subsystem frequency band are set to offset subcarrier; On this counteracting subcarrier, no longer launch normal traffic signal, but emission can be offset main system and at the out-of-band useful subcarrier of subsystem the subcarrier in the said subsystem frequency band produced interference signals.

In another embodiment; If said first sub-district has only a main system; Its frequency band, sub-carrier configuration, data receiver formula are identical with the aforementioned first sub-district main system; The main system bandwidth is w1 still, its useful subcarrier is set and the monolateral bound pair of the useful subcarrier of another neighbor cell subsystem is neat, and this main system is in the frequency band identical with another neighbor cell subsystem; Dispose with subcarrier and protection subcarrier by the mode identical, and send the data of main system on the useful subcarrier in this frequency band with the neighbor cell subsystem.At this moment; The first sub-district main system will be set to offset subcarrier with the adjacent plurality of sub carrier wave of the second sub-district subsystem frequency band, can offset main system in emission on this counteracting subcarrier and at the out-of-band useful subcarrier of above-mentioned subsystem the subcarrier in the said subsystem frequency band produced interference signals.This moment, Fig. 3 b was seen in frequency band and the configuration of subcarrier of the first sub-district main system, was equivalent to the result of the first sub-district main system and subsystem frequency spectrum mutual superposition among the embodiment.

When the amplitude of confirming the counteracting subcarrier and symbol; At first from main system, choose several as the weighting subcarrier in the useful subcarrier of the transmission main system data adjacent with said counteracting subcarrier, this weighting subcarrier is that the main system that needs to consider produces the subcarrier that disturbs to subsystem.For the purpose of accurately, can choose institute and might produce the subcarrier that disturbs as the weighting subcarrier, but consider the decay of signal subsystem, also can only choose main system influences bigger parton carrier wave as the weighting subcarrier to subsystem.If the weighting subcarrier is limited m, the position of weighting subcarrier is positioned at f ₁₁+ (N _Used2+ N _G2+ L) * Δ f is to f ₁₁+ (N _Used2+ N _G2+ L+m) * Δ f, shown in Fig. 3 b, the weighting subcarrier-modulated be normal data, its amplitude is normal subscriber signal.

Amplitude and symbol according to above-mentioned weighting subcarrier; Confirm the interference on the frequency of its useful subcarrier in said subsystem frequency band; According to offsetting of the requirement of said weighting subcarrier, confirm the amplitude and the symbol of said counteracting subcarrier to useful subcarrier interference in the said subsystem frequency band.The counteracting subcarrier can balance out the influence that main system weighting subcarrier part produces subsystem to the influence of subsystem; Make as far as possible promptly that to offset the amplitude of disturbing on subcarrier and the frequency of weighting subcarrier to the useful subcarrier of said subsystem identical; Opposite in sign; If the L number of sub-carrier of main ofdm system is as offsetting subcarrier, the position of offsetting subcarrier is positioned at f ₁₁+ (N _Used2+ N _GR2) * Δ f is to f ₁₁+ (N _Used2+ N _G2+ L) * and Δ f, shown in the dotted line subcarrier among Fig. 3 b, offset subcarrier and do not modulate user data.

Concrete computational methods are following:

If L amplitude vector of offsetting subcarrier is G _L:

G _L＝[g ₁，g ₂，…，g _L] ^T (2)

If the amplitude vector of m weighting subcarrier is A _m:

A _m＝[a ₁，a ₂，…，a _m] ^T (3)

The matrix transpose operation of T representing matrix in the formula.

L range signal of offsetting subcarrier choosing main ofdm system is the weighted sum of m weighting subcarrier amplitude:

G _L＝C×A _m (4)

C is L * m weighting matrix in the formula: C=[c _Lm] _{L * m}

Choose the element c of weighting matrix C _1m, make the weighting subcarrier of winner's ofdm system and offset the monolateral band energy of subcarrier at f ₂₁To f ₂₂Sum is minimum, C _Lm, L and m can calculate through the optimization algorithm of routine: the target function of promptly choosing optimization algorithm is the f of the subcarrier of main system at subsystem ₂₁To f ₂₂Between the amplitude energy with, find the solution energy and C hour _Lm, L and m value get final product.At this moment, offset subcarrier and weighting subcarrier f at subsystem ₂₁To f ₂₂Between amplitude cancel each other, thereby eliminate of the influence of main system signal to the useful bandwidth signal of subsystem.

For example, establish the f of the subcarrier of main system at subsystem ₂₁To f ₂₂Between single-sideband amplitude be s, offset the f of subcarrier at subsystem ₂₁To f ₂₂Between single-sideband amplitude be c (opposite in sign), then find the solution C based on optimization algorithm _Lm, L and m formula following:

$C_{\mathrm{lm}},L,m=\underset{C_{\mathrm{lm}},L,m}{\min }\left\{\right|s-c\left|\right\}---\left(5\right)$

Min representes that the value in the optimization braces is minimum in the formula, || signed magnitude arithmetic(al) is asked in expression.

The monolateral band of subcarrier (no matter be the weighting subcarrier, or offset subcarrier) is obeyed the sinc function, and promptly amplitude is a _m, frequency is f _mThe sideband amplitude of subcarrier at the frequency f place be:

$s\left(f\right)=a_m\×\frac{\sin (\mathrm{\π}(f-f_m)/\mathrm{\Δf})}{\mathrm{\π}(f-f_m)/\mathrm{\Δf}}---\left(6\right)$

Inferior ofdm system in main ofdm system in above-mentioned first sub-district and the second adjacent sub-district has constituted a kind of compatible system that comprises multiple ofdm system in the different districts; Wherein the frequency band of subsystem is within the frequency band of main system; And main system is identical with the subcarrier spacing of subsystem; The main system of first sub-district will be adjacent with said subsystem frequency band one or more useful sub-carrier configuration for offsetting subcarrier; On said counteracting subcarrier, transmit, its amplitude and symbol should make this signal cancellation main system in the interference of out-of-band other the useful subcarrier of subsystem to the useful subcarrier generation of said subsystem.

With the IEEE802.16m system of 20MHz bandwidth and the 802.16E system spectrum coexistence of 5MHz bandwidth is example; If adopt above-mentioned two kinds of systems in the sub-district 1; Adopted the 802.16E system of 5MHz bandwidth in the neighbor cell 2, IEEE802.16m system and 802.16E system all adopt the modulation system of OFDM.In order to realize two kinds of ofdm system frequency spectrum coexistences of different bandwidth in two sub-districts; And the 16m system in the sub-district 1 can not produce the 16e system in the sub-district 2 and disturb; At first two kinds of ofdm systems all adopt the identical FFT conversion of subcarrier spacing, in this example, and Δ f=10.9375MHz.

To the 802.16E system of 5MHz, through 512 FFT conversion, the IEEE802.16E band system band of 5MHz is transformed to the subcarrier of 512 independences, quadrature, wherein useful sub-carrier number is N _Used2=420, left side protection sub-carrier number is N _GL2=46, it is N that sub-carrier number is protected on the right side _GR2=46.Shown in Fig. 2 b.For 16e system in the sub-district 1 and the 16e system in the sub-district 2, its frequency band, sub-carrier configuration and data receiver formula are all identical, and the 16e system of hereinafter describing comprises 16e system and the 16e system in the sub-district 2 in the sub-district 1.

To the IEEE802.16m system of 20MHz, through 2048 FFT conversion, the IEEE802.16m band system band of 20MHz is transformed to the subcarrier of 2048 independences, quadrature, wherein useful sub-carrier number is N _Used1=1680, left side protection sub-carrier number is N _GL1=184, right protection sub-carrier number is N _GR1=184.Shown in Fig. 2 a.

When the 20MHz bandwidth was shared by the IEEE802.16e of the IEEE802.16m of 20MHz system and 5MHz system, at this moment, the shared frequency band of two kinds of ofdm systems was the bandwidth of IEEE802.16m system (main ofdm system), i.e. 20MHz.

At first, through 2048 FFT conversion, be the subcarrier of 2048 independences, quadrature with the frequency band transformation of 20MHz, wherein, share of the boundary belt setting of the boundary belt of frequency band (20MHz) according to main ofdm system, i.e. left side protection sub-carrier number is N _GL1=184, right protection sub-carrier number is N _GR1=184.

Secondly, on 2048 number of sub-carrier of sharing frequency band, 512 number of sub-carrier of 5MHz IEEE802.16e system are set, in this 512 number of sub-carrier, left side protection subcarrier N are set according to the standard of 5MHz IEEE802.16e system _GL2=46, useful subcarrier N _Used2=420, and right protection subcarrier N _GR2=46, the useful subcarrier left margin that the 802.16e system is set aligns with the useful subcarrier left margin of main system.Among Fig. 3 a be two systems when sharing frequency band subcarrier sketch map is set; In the drawings; 802.16e the useful subcarrier of system aligns with the on the left side circle place, useful subcarrier border of main system, promptly the 47th number of sub-carrier of 802.16e system is set on the 185th number of sub-carrier of main system.

Two system subcarriers through after the useful subcarrier alignment are set to; From 1 to 184 is the protection subcarrier of shared band; 185 to 604 subcarrier allocation is given the available subcarrier of 5MHz IEEE802.16e system, and 605 to 650 subcarrier allocation gives 5MHz IEEE802.16e system as right boundary belt.651 to 1864 subcarrier is the residue available subcarrier (being that 16m system available subcarrier is taken the remaining available subcarrier in back by the 16e system) of IEEE802.16m system, and 1865 to 2048 subcarrier is the right side protection subcarrier of IEEE802.16m system.

Take subcarrier subsystem is taken the interference of subcarrier in order to reduce main system, it is L=6 that the number of offsetting subcarrier is set, and the number that the weighting subcarrier is set is 12, and then weighting matrix is C=[c _Lm] _{6 * 12}Offset subcarrier and be positioned at 651 to 656 sub-carrier positions, the weighting subcarrier then is positioned at 657 to 668 position.Choose the element [c of weighting matrix C _Lm] _{6 * 12}, make that residue available subcarrier amplitude in the available subcarrier position range of 16e system of 16m system is minimum, thereby the residue available subcarrier of having eliminated the 16m system causes interference to 16e system available subcarrier.

Certainly; The present invention also can have other various embodiments; Under the situation that does not deviate from spirit of the present invention and essence thereof; Those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.

For example; Needs according to system carry out boundary alignment; It might be the left margin alignment; Also might be right margin alignment, the configuration of its frequency band and subcarrier be shown in Fig. 3 c, and the right margin of the useful subcarrier in the right margin of the useful subcarrier in the promptly said subsystem frequency band and the said main system frequency band aligns.

Claims (10)

1. the frequency spectrum sharing method when using multiple ofdm system in the different districts; Ofdm system in first sub-district is a main system; Ofdm system in the second adjacent sub-district is a subsystem, and wherein the frequency band of subsystem is within the frequency band of main system, and main system is identical with the subcarrier spacing of subsystem; It is characterized in that

Send data on the useful subcarrier of the subsystem of said second sub-district in its frequency band, with the protection sub-carrier signal power zero setting of both sides;

The main system of said first sub-district will be adjacent with said subsystem frequency band one or more useful sub-carrier configuration for offsetting subcarrier; On said counteracting subcarrier, transmit; Its amplitude and symbol should make this signal cancellation main system in the interference of out-of-band other the useful subcarrier of subsystem to the useful subcarrier generation of said subsystem, at first from main system, choose several as the weighting subcarrier in the useful subcarrier of the transmission main system data adjacent with said counteracting subcarrier; According to the amplitude and the symbol of said weighting subcarrier,, confirm the amplitude and the symbol of said counteracting subcarrier then according to offsetting of the requirement of said weighting subcarrier to useful subcarrier interference in the said subsystem frequency band.

2. the method for claim 1 is characterized in that,

Also there is a subsystem in said first sub-district; All the subsystem with second sub-district is identical with sub-carrier configuration, data receiver formula for the frequency band of this subsystem, and said main system is with all the useful subcarrier signals transmitting power zero setting on inherent this subsystem frequency band of its frequency band.

3. the method for claim 1 is characterized in that,

Said first sub-district has only a main system; This main system is in the frequency band identical with said subsystem; Dispose with subcarrier, protection subcarrier and transmission data by the identical mode of said subsystem, what wherein send on the useful subcarrier in this frequency band is the data of main system.

4. like claim 1,2 or 3 described methods, it is characterized in that,

When configuration; The left margin of the useful subcarrier in the left margin of the useful subcarrier in the said subsystem frequency band and the said main system frequency band is alignd, and perhaps the right margin with the useful subcarrier in the right margin of the useful subcarrier in the said subsystem frequency band and the said main system frequency band aligns.

5. the method for claim 1 is characterized in that, the signal that said counteracting subcarrier sends is further confirmed by following method:

If L amplitude vector of offsetting subcarrier is G _L: G _L=[g ₁, g ₂..., g _L] ^T, the amplitude vector of establishing m weighting subcarrier is A _m: A _m=[a ₁, a ₂..., a _m] ^T, wherein, the transposition of T representing matrix;

Choosing the amplitude of offsetting subcarrier is the weighted sum of weighting subcarrier amplitude: G _L=C * A _m, wherein, C is L * m weighting matrix: C=[c _Lm] _{L * m}, said c _Lm, L and m calculate through optimization algorithm, makes that promptly the monolateral band energy sum on said weighting subcarrier and the said counteracting subcarrier useful subcarrier frequency in the subsystem frequency band is minimum.

6. a compatible system that is included in the multiple ofdm system that adopts in the different districts comprises the main ofdm system in first sub-district, hereinafter to be referred as main system; And the inferior ofdm system in the second adjacent sub-district; Hereinafter to be referred as subsystem, wherein the frequency band of subsystem is within the frequency band of main system, and main system is identical with the subcarrier spacing of subsystem; It is characterized in that

Send data on the useful subcarrier of the subsystem of said second sub-district in its frequency band, with the protection sub-carrier signal power zero setting of both sides;

The main system of said first sub-district will be adjacent with said subsystem frequency band one or more useful sub-carrier configuration for offsetting subcarrier; On said counteracting subcarrier, transmit; Its amplitude and symbol should make this signal cancellation main system in the interference of out-of-band other the useful subcarrier of subsystem to the useful subcarrier generation of said subsystem, at first from main system, choose several as the weighting subcarrier in the useful subcarrier of the transmission main system data adjacent with said counteracting subcarrier; According to the amplitude and the symbol of said weighting subcarrier,, confirm the amplitude and the symbol of said counteracting subcarrier then according to offsetting of the requirement of said weighting subcarrier to useful subcarrier interference in the said subsystem frequency band.

7. compatible system as claimed in claim 6 is characterized in that,

Also there is a subsystem in said first sub-district; All the subsystem with second sub-district is identical with sub-carrier configuration, data receiver formula for the frequency band of this subsystem, and said main system is with all the useful subcarrier signals transmitting power zero setting on inherent this subsystem frequency band of its frequency band.

8. compatible system as claimed in claim 6 is characterized in that,

Said first sub-district has only a main system; This main system is in the frequency band identical with said subsystem; Dispose with subcarrier, protection subcarrier and transmission data by the identical mode of said subsystem, what wherein send on the useful subcarrier in this frequency band is the data of main system.

9. like claim 6,7 or 8 described compatible systems, it is characterized in that,

When configuration; The left margin of the useful subcarrier in the left margin of the useful subcarrier in the said subsystem frequency band and the said main system frequency band is alignd, and perhaps the right margin with the useful subcarrier in the right margin of the useful subcarrier in the said subsystem frequency band and the said main system frequency band aligns.

10. compatible system as claimed in claim 6 is characterized in that, the signal that said counteracting subcarrier sends is further confirmed by following method:

If L amplitude vector of offsetting subcarrier is G _L: G _L=[g ₁, g ₂..., g _L] ^T, the amplitude vector of establishing m weighting subcarrier is A _m: A _m=[a ₁, a ₂..., a _m] ^T, wherein, the transposition of T representing matrix;

Choosing the amplitude of offsetting subcarrier is the weighted sum of weighting subcarrier amplitude: G _L=C * A _m, wherein, C is L * m weighting matrix: C=[c _Lm] _{L * m}, said c _Lm, L and m calculate through optimization algorithm, makes that promptly the monolateral band energy sum on said weighting subcarrier and the said counteracting subcarrier useful subcarrier frequency in the subsystem frequency band is minimum.

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