CN1160890C - Digital wave beam forming method and module in radio communication system and its array receiver - Google Patents

Abstract

The present invention relates to a digital wave beam formation method in a wireless communication system. An algorithm adopted in the traditional wave beam forming method has large calculated amount, and therefore, the algorithm has high requirements for digital signal processors. The digital wave beam forming method provided by the present invention comprises the following steps: receiving array digital signals; estimating anticipant signal vector channel response according to a reference signal; calculating relevant wave beam coefficients by the formulas: Coeffi(k) = IIa<H>(thetai)RxdII<2> and Coeffi(k) = Coeffi(k) + alpha Coeffi(k-1); outputting a weighting vector corresponding to the maximal relevant coefficient; weighting array digital signals by the output weighting vector to output digital wave beam signals. The present invention also provides a digital wave beam formation module and an array receiver using the method.

Description

Digital beam formation method, module and array acceptor thereof in the wireless communication system

Technical field

The digital beam formation method and the wave beam that the present invention relates in the array acceptor of wireless communication system form module, also relate to use this digital beam method of formationing and wave beam formation arrays of modules receiver.

Background technology

For a long time, wireless communication system is faced with the contradiction between limited frequency spectrum resources and the constantly quick user who increases all the time.Although the wireless communication system that adopts time division multiple access (TDMA) and code division multiple access (CDMA) technology is compared the power system capacity that has improved to a certain extent with the system that adopts frequency division multiple access (FDMA) technology, this also far can not satisfy the demand of growing wireless traffic.Therefore people begin to utilize the spatial domain characteristic of channel, improve the capacity of receiving system as adopting diversity, sectorization and methods such as recently introduced switch multi-beam and adaptive array.These methods have improved capacity at the communication quality that has improved wireless communication system in varying degrees.

Diversity technique mainly utilizes spacing greater than uncorrelated this character of the signal that different antennae received of 10 carrier wavelengths, adopts high specific to merge the signal that each antenna receives, and system's anti-multipath decline performance is improved.

The sectorization method is that the sub-district is divided into 3,6,9 or 12 sectors, and there are supporting antenna and predetermined spectral range in each sector.Sectorization has reduced the communication channel interference to a certain extent, thereby has improved the communication quality of system.

The switch multi-beam is to form fixed beam on the different directions of sub-district, and the signal quality of desired signal in each wave beam is detected in the base station, selects best wave beam to receive.Why be called the switch multi-beam, wherein a main cause is, there is controlled switch in system on the path between each wave beam and each channel receiver in the process of selecting wave beam, i.e. so-called " switch matrix ".After a certain wave beam is selected, the channel selector closure between this wave beam and the corresponding receiver, and the switch of other path disconnects.

Adaptive array is according to maximum signal noise ratio principle, maximum-likelihood criterion and minimum mean square error criterion etc., the signal that each antenna is received is weighted merging adaptively, interference and noise signal are suppressed effectively, thus the overall performance of raising wireless system.

Owing to adopt deversity scheme to need gap ratio big (generally greater than 10 wavelength) between the antenna, so the many more occupation space of antenna are big more, and the actual space that can utilize, base station is very limited.In addition, though the deversity scheme that adopts high specific to merge has anti-multipath decline effect, can not effectively suppress interference signal.

Common sectorization method is to adopt 3 sectors or 6 sectors now, why does not adopt more sector to be because the sector divides manyly more, and each sector available spectrum resource is just few more, has reduced junction efficiency.And the sector divides manyly more, and wave beam overlapping between the different sectors is just many more, and cochannel is disturbed to be increased, and systematic function descends.

The switch multi-beam also can be thought the sectorization method in some sense, and just the division of sector is formed by the different beams dynamic combined.Owing to always select the wave beam of " the best " to receive when receiving, thus different with the sectorization method, overlapping between the wave beam of switch multi-beam must many more gain losses that can reduce wave beam and wave beam intersection on the contrary.The wave beam of existing switch multiple-beam system forms the narrow beam coverage cell of a plurality of pointing space different directions by a directional antenna or the coherent superposition that adopts radio frequency phase-shift network (as the Butler matrix) to carry out.Theoretically, if wave beam is narrow more, the airspace filter performance of beam switch multi-beam antenna is good more, and it is strong more to suppress interference performance.But because the phase shift precision of restriction of the bore of directional antenna and radio frequency phase-shift network is limited, beamwidth is limited, and overlapping also limited between the wave beam is restricted existing switch multiple-beam system on the improvement ability of system communication capacity.In addition, the switch matrix of existing switch multiple-beam system is realized by the radio-frequency (RF) switch device, has increased the hardware cost of system.

Adaptive array adopts adaptive algorithm to obtain the array weight coefficient according to different criterions, though can make systematic function reach optimum to a certain extent, but the amount of calculation that the adaptive algorithm of function admirable often requires is bigger, to the requirement height of digital signal processor spare, many algorithms adopt existing high speed processing chip also can't realize.

Summary of the invention

For these reasons, and in conjunction with switch multi-beam and adaptive array technology, the object of the present invention is to provide a kind of formation method that is used for the array acceptor digital beam of wireless communication system, this method has stable, the amount of calculation features of smaller of algorithm performance, therefore, the hardware cost of realization is low, systematic function is good.

Another object of the present invention is to provide that digital beam forms module in a kind of array acceptor of wireless communication system, the employed algorithm performance of this digital beam formation module is stable, amount of calculation is less, therefore, the hardware cost of realization is low, systematic function is good.

A further object of the present invention is to provide a kind of array acceptor of wireless communication system, wherein employed digital beam forms module and adopts the above-mentioned digital beam formation method of the present invention, has stable, the amount of calculation features of smaller of algorithm performance, therefore, the hardware cost of realization is low, systematic function is good.

According to above-mentioned purpose of the present invention, digital beam formation method provided by the invention comprises the following steps:

(a) receiving array digital signal, wherein said array digital signal can be expressed as:

$X\left(t\right)=\underset{l=i}{\overset{L}{\mathrm{\&Sigma;}}}a\left({\mathrm{\&theta;}}_l\right)h_l\left(t\right)s(t-{\mathrm{\&tau;}}_l)+n\left(t\right)$

In the formula, l=1,2 ..., L is the multipath number, a (θ _l) be the M*1 dimensional vector, represent l bar multipath signal the array response vector on M bay relevant, θ with direction θ _iIt is the direction of arrival of l bar multipath; h _l(t) be the decline of l bar multipath signal experience; S (t) is the desired signal of emission, τ _lIt is the time delay of l bar multipath signal; N (t) is that array disturbs and noise signal;

(b), utilize following formula to estimate desired signal vector channel responses (R according to the reference signal in the described array digital signal (s (t)) _Xd):

R _xd＝E[X(t)s*(t)]，

In the formula, * represents complex conjugate operation;

(c) with described desired signal vector signal (R _Xd) and weighing vector W _i=a ^H(θ _i) carry out following computing, obtain wave beam coefficient correlation (Coeff _i(k)),

Coeff _i(k)＝‖a ^H(θ _i)R _xd‖ ²，

Coeff _i(k)＝Coeff _i(k)+αCoeff _i(k-1)

In the formula, subscript H represents the conjugate transpose computing; Coeff _i(k) the wave beam coefficient correlation of k period of expression, α carries out the non-coherent forgetting factor when accumulating;

(d) more described wave beam coefficient correlation (Coeff _i(k)), obtain maximum coefficient correlation (Coeff _Max), output and described maximum correlation coefficient (Coeff _Max) corresponding weighing vector W _Max=α ^H(θ _Max);

(e) with the weighing vector W that exports _Max=a ^H(θ _Max) described array digital signal X (t) is weighted, with output digital beam signal.

According to above-mentioned digital beam formation method, after described step (c), also comprise the following steps:

(c1) each wave beam coefficient correlation (Coeff that relatively obtains _i(k)), will sort from big to small greater than the coefficient correlation of a correlation coefficient threshold (β);

(c2) export and the corresponding weighing vector of described coefficient correlation with selective sequential from big to small;

(c3) judge that whether the digital beam quality of signals of exporting meets the demands, if do not satisfy, then returns above-mentioned steps (c2).

According to another object of the present invention, the invention provides a kind of digital beam that is used for cdma system and form module, comprising:

Multipath searching and tracking cell, the receiving array digital signal utilizes in the described array digital signal arbitrarily one or more digital signal to carry out Multipath searching and follow the tracks of and handle, and the multidiameter delay signal is provided;

Despread unit receives described array digital signal, and links to each other with described Multipath searching and tracking cell, and the multidiameter delay signal that utilizes described Multipath searching and tracking cell to provide is poised for battle the column of figure signal and is carried out despreading, the output despread signal;

The weighing vector maker links to each other with described despread unit, receives the described despread signal of described despread unit output, produces weighing vector;

Multiplier multiplies each other the despread signal of described despread unit output and the weighing vector of described weighing vector maker output; And

Adder links to each other with the output of described multiplier, with the output addition of described multiplier, and output digital beam signal;

Described weighing vector maker comprises:

Reference signal generator takes out reference signal from described array digital signal;

Memory is stored NB array response vector;

Desired signal vector channel responses estimation module links to each other with described reference signal generator, utilizes following formula to estimate desired signal vector channel responses (R _Xd):

R _xd＝E[X(t)s*(t)]，

In the formula, * represents complex conjugate operation, the described reference signal that s* (t) provides for described reference signal generator;

Wave beam coefficient correlation estimation module links to each other with described memory with described desired signal vector channel responses estimation module, utilizes following formula to estimate wave beam coefficient correlation (Coeff _i(k)),

Coeff _i(k)＝‖a ^H(θ _i)R _xd‖ ²，

Coeff _i(k)＝Coeff _i(k)+αCoeff _i(k-1)

In the formula, subscript H represents the conjugate transpose computing; Coeff _i(k) the wave beam coefficient correlation of k period of expression, a (θ _i) be array response vector, α is the forgetting factor when carrying out the accumulation of non-coherent;

The weighing vector output module links to each other with described wave beam coefficient correlation estimation module, selects the weighing vector output corresponding to wave beam coefficient correlation maximum, and described weighing vector is a ^H(θ _i).

According to a further object of the present invention, the present invention also provides a kind of array acceptor that is used for cdma system, comprising:

The aerial array of forming by a plurality of antennas;

Array digital signal generation module links to each other with described aerial array, and the aerial array analog signal conversion that is used for described aerial array is received becomes the array digital signal;

Digital beam forms module, links to each other with described array digital signal generation module, is used for the array digital signal of described array digital signal generation module is formed one or more signal beams on each channel;

The digital receiver module forms module with described digital beam and links to each other, is used to receive one or more signal beams that the module of described digital beam formation forms on each channel, on time domain described signal beam is merged;

It is characterized in that described digital beam forms module, comprising:

Multipath searching and tracking cell, the receiving array digital signal utilizes in the described array digital signal arbitrarily one or more digital signal to carry out Multipath searching and follow the tracks of and handle, and the multidiameter delay signal is provided;

Despread unit receives described array digital signal, and links to each other with described Multipath searching and tracking cell, and the multidiameter delay signal that utilizes described Multipath searching and tracking cell to provide is poised for battle the column of figure signal and is carried out despreading, the output despread signal;

The weighing vector maker links to each other with described despread unit, receives the described despread signal of described despread unit output, produces weighing vector;

Multiplier multiplies each other the despread signal of described despread unit output and the weighing vector of described weighing vector maker output; And

Adder links to each other with the output of described multiplier, with the output addition of described multiplier, and output digital beam signal;

Described weighing vector maker comprises:

Reference signal generator takes out reference signal from described array digital signal;

Memory is stored NB array response vector;

Desired signal vector channel responses estimation module links to each other with described reference signal generator, utilizes following formula to estimate desired signal vector channel responses (R _Xd):

R _xd＝E[X(t)s*(t)]，

In the formula, * represents complex conjugate operation, the described reference signal that s* (t) provides for described reference signal generator;

Wave beam coefficient correlation estimation module links to each other with described memory with described desired signal vector channel responses estimation module, utilizes following formula to estimate wave beam coefficient correlation (Coeff _i(k)),

Coeff _i(k)＝‖a ^H(θ _i)R _xd‖ ²，

Coeff _i(k)＝Coeff _i(k)+αCoeff _i(k-1)

In the formula, subscript H represents the conjugate transpose computing; Coeff _i(k) the wave beam coefficient correlation of k period of expression, a (θ _i) be array response vector, α is the forgetting factor when carrying out the accumulation of non-coherent;

The weighing vector output module links to each other with described wave beam coefficient correlation estimation module, selects the weighing vector output corresponding to wave beam coefficient correlation maximum, and described weighing vector is a ^H(θ _i).

As mentioned above, because digital beam formation method of the present invention has adopted a kind of new easy algorithm, thereby can simplify hardware configuration, and preferable systematic function is provided simultaneously.

Description of drawings

Describe embodiments of the invention in detail below in conjunction with accompanying drawing.

Fig. 1 is the functional block diagram of array acceptor of the present invention;

Fig. 2 shows the wave beam schematic diagram of coverage cell;

Fig. 3 shows the built-in function block diagram of the digital beam formation module 104 among Fig. 1;

Fig. 4 shows the built-in function block diagram of the weighing vector maker among Fig. 3;

Fig. 5 shows the flow chart of digital beam formation method of the present invention;

Simulation result when Fig. 6 shows the present invention and is applied to cdma system.

Embodiment

Fig. 1 is an array acceptor schematic diagram of the present invention.This receiver comprises that mainly aerial array 102, array digital signal generation module 103, digital beam form module 104 and digital receiver module 105.The main effect of array digital signal generation module 103 is that the aerial array analog signal conversion that will receive from aerial array 102 becomes to supply the array digital signal of digital processing, comprising receiving element (RX) 106 and analog to digital converting unit (A/D) 107 are arranged.Digital beam forms module 104 can form one or more digital beams to a channel, for example to a code channel of cdma system, digital beam forms module 104 can form wave beam respectively to the different multipath signals of identical code channel, signal after wave beam forms is delivered to the corresponding finger of digital receiver module 105 (can adopt the Rake receiver), signal is merged in time domain by digital receiver module 105.Because to digital signal, digital beam forms module 104 and can change flexibly according to the different requirement of system with analog signal conversion.

Form module 104 utilization ARRAY PROCESSING algorithms for the digital beam shown in 1 figure signal that receives is handled, form so-called wave beam, the signal quality of exporting in the wave beam is improved, thereby improve the performance of whole receiver.Therefore, the complexity of digital beam formation array processing method that module 104 adopted and realization, stability etc. are directly connected to the quality of systematic function.The present invention proposes a kind of simple, reliable, multi-beam array receiving method of being easy to realize.

The digital signal of array digital signal generation module 103 outputs in the array acceptor shown in Figure 1 can be expressed as:

$X\left(t\right)=\underset{l=1}{\overset{L}{\mathrm{\&Sigma;}}}a\left({\mathrm{\&theta;}}_l\right)h_l\left(t\right)s(t-{\mathrm{\&tau;}}_l)+n\left(t\right)----\left(1\right)$

In the formula, l=1,2 ..., L is the multipath number, a (θ _l) be the M*1 dimensional vector, represent l bar multipath signal the array response on M bay relevant, θ with direction θ _iIt is the direction of arrival of l bar multipath; h _l(t) be the decline of l bar multipath signal experience; S (t) is the desired signal of emission, τ _lIt is the time delay of l bar multipath signal; N (t) is that array disturbs and noise signal;

According to the form of aerial array 102,, can pre-determine the array response a (θ that array has the signal on the different directions as uniform straight line array, circle etc. _i) (i=1,2 ..., N _B).Use W _i=a ^H(θ _i) (subscript H represents the computing of conjugation rotor) as the weighting of each antenna element received signal of array, be equivalent to array at θ _iDirection forms wave beam, and the array digital signal X (t) that receives is carried out airspace filter.For effect and the system digits signal handling capacity of taking into account the spatial domain matched filtering, N _BValue should make a ^H(θ _i) gain and the maximum gain in all wave beams of plotted point 201 differs-2 to 0dB between the wave beam that forms and the wave beam, promptly the graticule among Fig. 2 202 is between-2 to 0dB.

Fig. 3 shows the built-in function block diagram of the digital beam formation module 104 among Fig. 1.As shown in Figure 3, digital beam forms module 104 and includes Multipath searching and tracking cell 401, despread unit 402, weighing vector maker 404, multiplier 405, adder 406.Array digital signal generation module 103 becomes the array digital signal with the analog signal conversion that antenna 102 receives, and sends into digital beam formation module 104.Multipath searching and tracking module 401 that digital beam forms in the module 104 utilize wherein any one or more digital signal to carry out Multipath searching and follow the tracks of processing, and the multidiameter delay signal is offered despread unit 402.The multipath signal of 402 pairs of appointments of despread unit carries out despreading, obtains despread signal.Signal after the despreading is divided into two-way, one the tunnel enters weighing vector maker 404, another road is as being weighted data, prepare to carry out multiplying and finally obtain the digital beam data after adder 406 merges by multiplier 405 with the weighing vector of weighing vector maker 404 outputs, these data output to digital receiver module 105 and point accordingly.

Among Fig. 3 the structure of weighing vector maker 404 as shown in Figure 4, by desired signal vector channel responses estimation module 501, wave beam coefficient correlation estimation module 502, weighing vector output module 503, reference signal generator 504 and memory 505.

In most of communication systems, all comprising in the signal of emission is Given informations such as the known training sequence of receiving terminal, frequency pilot sign in advance.For example in gsm system, the known training sequence of 26 bits is arranged in each normal (Norma) l burst; In the WCDMA system, in each time slot (Slot) of DPCCH known pilot symbols is arranged.Receiving terminal can utilize these Given informations directly or indirectly to obtain called reference signal s (t).Reference signal generator 504 extracts reference signal s (t) exactly from array digital signal X (t), and offers 501 uses of desired signal vector channel responses estimation module.

Desired signal vector channel responses estimation module 501 obtains reference signal s (t) from reference signal generator 504, estimate desired signal vector channel responses R then _Xd, estimation formulas is as follows:

R _xd＝E[X(t)s*(t)]＝a(θ _d)E[h _d(t)s(t)s*(t)]+E[n(t)s*(t)] (2)

In the formula, * represents complex conjugate operation, the described reference signal that s* (t) provides for described reference signal generator.In the actual mathematical computing, E[X (t) s* (t)] can use $\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}X\left(n\right)s*\left(n\right)$ Replace.And establish s (n) s* (n)=‖ s (n) ‖=1, therefore can obtain

R _xd＝a(θ _d)E[h _d(t)]+E[n(t)s*(t)] (3)

From formula (3) as can be seen, when time during long enough, E[h _d(t)]=0, E[n (t) s* (t)]=0, can cause the information relevant with desired signal (first on formula (3) left side) like this is zero, can't further carry out ARRAY PROCESSING, therefore, correlation time can not be oversize.Correlation time, weak point then can produce E[h _d(t)]=C _h, E[n (t) s* (t)]=C _nIn order to make ‖ C _h‖ ²Make C greatly, _nIn the mould of element square little, should will ask E[h _d(t)] time is selected near coherence time as far as possible.

Wave beam coefficient correlation estimation module 502 utilizes following formula to estimate wave beam coefficient correlation (Coeff _i(k)),

Coeff _i(k)=‖ a ^H(θ _i) R _Xd‖ ²(4) subscript H represents conjugate transpose computing, Coeff in the formula (4) _i(k) the wave beam coefficient correlation of k period of expression.Array response vector a (θ _i) corresponding with the wave beam of array formation, can from memory 505, obtain (in memory 505, having stored N in advance _BIndividual array response vector), i.e. array response vector a ^H(θ _i) as the weighing vector W of array data _iThe time, can make array at θ _iForm wave beam i on the direction.Pre-determining N _BIndividual array response a (θ _i) time, N _BValue relate to system requirements and chip disposal ability.In order to take into account ARRAY PROCESSING effect and system digits signal handling capacity, in the cell range of receiver service, N _BValue should make a ^H(θ _i) gain and the maximum gain in all wave beams of plotted point 201 differs-2 to 0dB between the wave beam that forms and the wave beam, promptly the graticule among Fig. 2 202 is between-2 to 0dB.

In order to reduce the influence of distracter, further carry out non-coherent accumulation, that is:

Coeff _i(k)=Coeff _i(k)+α Coeff _i(k-1) in (5) formula (5), α is a forgetting factor, is a constant, and it is relevant with the factors such as translational speed of travelling carriage in the sub-district, generally gets 0≤α≤1.From formula (4) and formula (5), be not difficult to find out N _BThe coefficient Coeff of maximum in the individual wave beam coefficient correlation _MaxPairing direction θ _MaxPromptly be and the immediate direction of desired signal therefore can select array weight vectors W=a ^H(θ _Max), to obtain maximum gain.

Weighing vector output module 503 is from wave beam coefficient correlation Coeff _i(k) find out maximum coefficient correlation Coeff in _Max, output is measured big coefficient correlation Coeff with this then _MaxCorresponding weighing vector W _Max=a ^H(θ _Max).The weighing vector of this output offers the multiplier 405 among Fig. 3, with the signal multiplication of despread unit 402 outputs.

Describe the composition structure and the operation principle of array acceptor of the present invention above in detail, having described the present invention especially emphatically has the digital beam of original creation part to form the formation and the operation principle of module 104.From top announcement as can be seen, the module 104 that forms digital beam of the present invention realizes having utilized a kind of new digital beam formation method, in this method, for obtaining digital beam, utilize above-mentioned formula (3) and (4) to obtain the coefficient correlation of desired signal energy in each wave beam of reflection, selected to determine digital beam according to coefficient correlation then.For making this method more clear, Fig. 5 shows the flow chart of digital beam formation method of the present invention.

As shown in Figure 5, at first, at step S1 receiving array digital signal X (t), corresponding to Fig. 1, promptly digital beam forms module 104 from array digital signal generation module 103 receiving array digital signal X (t).

Then, at step S2, estimate desired signal vector channel responses Rxd according to reference signal s (t), the formula of its estimation can be referring to above-mentioned formula (2).The work that this step S2 is finished corresponding to expectation signal phasor channel response estimation module 501 among Fig. 4.

Then, obtain wave beam coefficient correlation Coeff at step S3 _i(k), its operational formula is above-mentioned formula (4) and (5), and concrete method can be with reference to top description.This step work is to be finished by the wave beam coefficient correlation estimation module 502 among Fig. 4.

In conjunction with the description that Fig. 4 did, step then is the wave beam coefficient correlation Coeff that relatively obtains as top _i(k), obtain maximum coefficient correlation Coeff _Max, output and maximum correlation coefficient Coeff _MaxCorresponding weighing vector W _Max=a ^H(θ _Max).

But, when the Signal Interference and Noise Ratio (SINR) of input array digital signal hour because the direction that integration time, high-amplitude wave bundle may appear in weak point is not the direction of desired signal.At this moment can be according to making further to select (referring to Fig. 1) by the signal quality of data path 109 feedback solution tonal signals by digital receiver 105.Therefore, provide another embodiment here, that is, as shown in Figure 5, after step S3, the coefficient correlation Coeff of desired signal energy in each wave beam of Huo Deing relatively _i(k), will sort from big to small greater than the coefficient correlation of a correlation coefficient threshold (β, β can determine according to number of users possible in the coverage) (step S4); Then with from big to small selective sequential output and the corresponding weighing vector of coefficient correlation (step S5); At the signal of step S6 according to digital receiver module 105 feedbacks, judge whether the quality of output signal meets the demands, if do not satisfy, then return above-mentioned steps S5, till obtaining the satisfied signal of quality.

In method embodiment described herein, step S4 to S6 can be realized by weighing vector output module 503 shown in Figure 4.As can be seen from Figure 3, multi-beam selects module 403 to link to each other with digital receiver module 105 by feedback line 109, so that obtain the signal of expression signal quality from digital receiver module 105, if signal quality signal indication signal quality does not meet the demands, then multi-beam is selected module 403 output selection instructions, selecting and the corresponding digital beam output signal of next big coefficient correlation, meet the demands or coefficient correlation is less than correlation coefficient threshold (β) up to signal quality.Signal quality signal for 105 outputs of digital receiver module all can have the output of this signal in existing array acceptor, the present invention has just utilized this signal.Therefore, no longer concrete and describe the production method and the principle of this signal in detail at this.

The inventor has carried out emulation experiment at the up link of cdma system with digital beam formation method provided by the invention, its result as shown in Figure 6, the environmental parameter of its multipath can see table.

The multipath number	6
							Multidiameter delay (second)	0	310e-9	710e-9	1090e-9	1730e-9	2510e-9
The average fading factor of multipath (dB)	0dB	-1dB	-9dB	-10dB	-15dB	-20dB
							Spreading factor	256
The Doppler frequency	222Hz

As can be seen, adopt the present invention for 4 array element array acceptors, when input signal-to-noise ratio was the 2.2dB left and right sides, the error rate of digital receiver module output signal can be 10 ^-3Near, and single antenna digital receiver module just can make the error rate of output signal reach 10 when needing the signal to noise ratio of antenna end input signal to be the 8.2dB left and right sides ^-3Obviously adopt method provided by the invention, systematic function is significantly improved.

Claims (15)

1, a kind of digital beam formation method comprises the following steps:

(a) receiving array digital signal, wherein said array digital signal can be expressed as:

$X\left(t\right)=\underset{l=i}{\overset{L}{\mathrm{\&Sigma;}}}a\left({\mathrm{\&theta;}}_l\right)h_l\left(t\right)s(t-{\mathrm{\&tau;}}_l)+n\left(t\right)$

In the formula, l=1,2 ..., L is the multipath number, a (θ _l) be the M*1 dimensional vector, represent l bar multipath signal the array response vector on M bay relevant, θ with direction θ _iIt is the direction of arrival of l bar multipath; h _l(t) be the decline of l bar multipath signal experience; S (t) is the desired signal of emission, τ _lIt is the time delay of l bar multipath signal; N (t) is that array disturbs and noise signal;

(b), utilize following formula to estimate desired signal vector channel responses (R according to the reference signal in the described array digital signal (s (t)) _Xd):

R _xd＝E[X(t)s*(t)]，

In the formula, * represents complex conjugate operation;

(c) with described desired signal vector signal (R _Xd) and weighing vector W _i=a ^H(θ _i) carry out following computing, obtain wave beam coefficient correlation (Coeff _i(k)),

Coeff _i(k)＝‖a ^H(θi) _xd‖ ²，

Coeff _i(k)＝Coeff _i(k)+αCoeff _i(k-1)

In the formula, subscript H represents the conjugate transpose computing; Coeff _i(k) the wave beam coefficient correlation of k period of expression, α carries out the non-coherent forgetting factor when accumulating;

(d) more described wave beam coefficient correlation (Coeff _i(k)), obtain maximum coefficient correlation (Coeff _Max), output and described maximum correlation coefficient (Coeff _Max) corresponding weighing vector W _Max=a ^H(θ _Max);

(e) with the weighing vector W that exports _Max=a ^H(θ _Max) described array digital signal X (t) is weighted, with output digital beam signal.

2, digital beam formation method as claimed in claim 1 is characterized in that, also comprises the following steps: after described step (c)

(c1) each wave beam coefficient correlation (Coeff that relatively obtains _i(k)), will sort from big to small greater than the coefficient correlation of a correlation coefficient threshold (β);

(c2) export and the corresponding weighing vector of described coefficient correlation with selective sequential from big to small;

(c3) judge that whether the digital beam quality of signals of exporting meets the demands, if do not satisfy, then returns above-mentioned steps (c2).

3, digital beam formation method as claimed in claim 1 or 2 is characterized in that, described E[X (t) s* (t)] computing usefulness $\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}X\left(n\right)s*\left(n\right)$ Replace.

4, digital beam formation method as claimed in claim 1 or 2 is characterized in that, the value of described forgetting factor is 0≤α≤1.

5, digital beam formation method as claimed in claim 3 is characterized in that, the value of described forgetting factor is 0≤α≤1.

6, a kind of digital beam forms module, comprising:

Multipath searching and tracking cell, the receiving array digital signal utilizes in the described array digital signal arbitrarily one or more digital signal to carry out Multipath searching and follow the tracks of and handle, and the multidiameter delay signal is provided;

Despread unit receives described array digital signal, and links to each other with described Multipath searching and tracking cell, and the multidiameter delay signal that utilizes described Multipath searching and tracking cell to provide is poised for battle the column of figure signal and is carried out despreading, the output despread signal;

The weighing vector maker links to each other with described despread unit, receives the described despread signal of described despread unit output, produces weighing vector;

Multiplier multiplies each other the despread signal of described despread unit output and the weighing vector of described weighing vector maker output; And

Adder links to each other with the output of described multiplier, with the output addition of described multiplier, and output digital beam signal;

Described weighing vector maker comprises:

Reference signal generator takes out reference signal from described array digital signal;

Memory is stored NB array response vector;

Desired signal vector channel responses estimation module links to each other with described reference signal generator, utilizes following formula to estimate desired signal vector channel responses (R _Xd):

R _xd＝E[X(t)s*(t)]，

In the formula, * represents complex conjugate operation, the described reference signal that s* (t) provides for described reference signal generator;

Wave beam coefficient correlation estimation module links to each other with described memory with described desired signal vector channel responses estimation module, utilizes following formula to estimate wave beam coefficient correlation (Coeff _i(k)),

Coeff _i(k)＝‖a ^H(θi)R _xd‖ ²，

Coeff _i(k)＝Coeff _i(k)+αCoeff _i(k-1)

In the formula, subscript H represents the conjugate transpose computing; Coeff _i(k) the wave beam coefficient correlation of k period of expression, a (θ _i) be array response vector, the forgetting factor when α carries out the accumulation of non-coherent;

The weighing vector output module links to each other with described wave beam coefficient correlation estimation module, selects the weighing vector output corresponding to wave beam coefficient correlation maximum, and described weighing vector is a ^H(θ _i).

7, digital beam as claimed in claim 6 forms module, it is characterized in that, described weighing vector maker also links to each other with the digital receiver module, be used to receive the signal quality signal of described digital receiver module output, if described signal quality signal indication signal quality does not meet the demands, described weighing vector output module output in the then described weighing vector maker is selected corresponding to for several times big weighing vector output of wave beam phase relation, carry out with this, up to signal quality meet the demands or described coefficient correlation less than correlation coefficient threshold (β).

8, form module as claim 6 or 7 described digital beams, it is characterized in that described E[X (t) s* (t) computing is used $\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}X\left(n\right)s*\left(n\right)$ Replace.

9, form module as claim 6 or 7 described digital beams, it is characterized in that the value of described forgetting factor is 0≤α≤1.

10, digital beam as claimed in claim 8 forms module, it is characterized in that the value of described forgetting factor is 0≤α≤1.

11, a kind of array acceptor comprises:

The aerial array of forming by a plurality of antennas;

Array digital signal generation module links to each other with described aerial array, and the aerial array analog signal conversion that is used for described aerial array is received becomes the array digital signal;

Digital beam forms module, links to each other with described array digital signal generation module, is used for the array digital signal of described array digital signal generation module is formed one or more signal beams on each channel;

The digital receiver module forms module with described digital beam and links to each other, is used to receive one or more signal beams that the module of described digital beam formation forms on each channel, on time domain described signal beam is merged;

It is characterized in that described digital beam forms module, comprising:

Multipath searching and tracking cell, the receiving array digital signal utilizes in the described array digital signal arbitrarily one or more digital signal to carry out Multipath searching and follow the tracks of and handle, and the multidiameter delay signal is provided;

Despread unit receives described array digital signal, and links to each other with described Multipath searching and tracking cell, and the multidiameter delay signal that utilizes described Multipath searching and tracking cell to provide is poised for battle the column of figure signal and is carried out despreading, the output despread signal;

The weighing vector maker links to each other with described despread unit, receives the described despread signal of described despread unit output, produces weighing vector;

Multiplier multiplies each other the despread signal of described despread unit output and the weighing vector of described weighing vector maker output; And

Adder links to each other with the output of described multiplier, with the output addition of described multiplier, and output digital beam signal;

Described weighing vector maker comprises:

Reference signal generator takes out reference signal from described array digital signal;

Memory is stored NB array response vector;

Desired signal vector channel responses estimation module links to each other with described reference signal generator, utilizes following formula to estimate desired signal vector channel responses (R _Xd):

R _xd＝E[X(t)s*(t)]，

In the formula, * represents complex conjugate operation, the described reference signal that s* (t) provides for described reference signal generator;

Wave beam coefficient correlation estimation module links to each other with described memory with described desired signal vector channel responses estimation module, utilizes following formula to estimate wave beam coefficient correlation (Coeff _i(k)),

Coeff _i(k)＝‖a ^H(θ _i)R _xd‖ ²

Coeff _i(k)＝Coeff _i(k)+αCoeff _i(k-1)

In the formula, subscript H represents the conjugate transpose computing; Coeff _i(k) the wave beam coefficient correlation of k period of expression, a (θ _i) be array response vector, α is the forgetting factor when carrying out the accumulation of non-coherent;

The weighing vector output module links to each other with described wave beam coefficient correlation estimation module, selects the weighing vector output corresponding to wave beam coefficient correlation maximum, and described weighing vector is a ^H(θ _i).

12, array acceptor as claimed in claim 11, it is characterized in that, described weighing vector maker also links to each other with the digital receiver module, be used to receive the signal quality signal of described digital receiver module output, if described signal quality signal indication signal quality does not meet the demands, described weighing vector output module output in the then described weighing vector maker is selected corresponding to for several times big weighing vector output of wave beam phase relation, carry out with this, up to signal quality meet the demands or described coefficient correlation less than correlation coefficient threshold (β).

13, form the module array receiver as claim 11 or 12 described digital beams, it is characterized in that described E[X (t) s* (t)] computing usefulness $\frac{1}{N}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}X\left(n\right)s*\left(n\right)$ Replace.

As claim 11 or 12 described array acceptors, it is characterized in that 14, the value of described forgetting factor is 0≤α≤1.

15, array acceptor as claimed in claim 13 is characterized in that, the value of described forgetting factor is 0≤α≤1.

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