CN104702302A - Intelligent antenna device and signal processing method based on IEEE802.11g protocol - Google Patents

Abstract

The invention relates to an intelligent antenna device and a signal processing method based on an IEEE802.11g protocol. The signal processing method comprises the following steps: step 1, receiving multiple digital signals; step 2, finding a long training sequence signal of the IEEE802.11g protocol from the multiple digital signals; step 3, taking the long training sequence signal as a reference signal, and working out a weight by a beam shaping algorithm; and step 4, performing weighted summation on the multiple digital signals by using the weight. The intelligent antenna device and the signal processing method of the invention are used for solving the problem of interference to wireless transmission in airports. Spatial filtering can be realized by performing weighted summation on signals received by array elements through a multi-antenna technology without changing the existing IEEE802.11a/g/n protocol, so as to achieve the purpose of enhancing expected signals and suppressing interference, and ultimately, improve the channel capacity, increase the speed and reduce the bit error rate.

Description

Based on smart antenna equipment and the signal processing method of IEEE802.11g agreement

Technical field

The invention belongs to wireless communication technology field, relate to a kind of wireless communications method, particularly relate to a kind of smart antenna equipment based on IEEE802.11g agreement and signal processing method.

Background technology

Along with present civil aviation aircraft air environment is increasing, day by day intelligent, its data stored are also day by day huge.The data of current airborne equipment carry out artificial data-moving mainly through portable hard drive.Modern New civil aviation passenger plane such as (Boeing 777 and 787) all carries TWLU(Terminal Wireless LAN Unit) radio transmission apparatus, transmits on-board data to ground when airport shelter bridge is stopped by wireless channel for aircraft.

At present, what TWLU adopted usually is IEEE802.11g wireless transmission protocol, OFDM (OFDM) technology has been used in IEEE802.11g, in agreement, physical layer data units PPDU is divided into 3 parts: PLCP targeting sequencing (PLCP Preamble), signal domain (Signal) and numeric field (Data).If Fig. 1, PLCP targeting sequencing is for input, automatic growth control, frequency deviation is estimated, synchronous etc.; PLCP targeting sequencing is made up of 10 short training sequences (t1 ~ t10) and 2 long training sequences (T1 ~ T2), and wherein, 2 long training sequences (T1 ~ T2) are changeless.The frequency range that TWLU equipment uses is in the face of the open free public frequency band of the equipment such as WiFi.In large-scale Civil Aviation Airport, the wireless network application for difference service is various, and wireless device is arranged net very intensive.Service provider's difference due to different radio equipment causes wireless frequency to use can not have unified planning, equipment with band channels interferes with each other seriously, make to access difficulty during the TWLU equipment work used at shelter bridge place, airport, transfer of data is unstable, and throughput is low.Because TWLU adopts IEEE802.11a/b/g wireless transmission protocol, and the design of passivity co-channel interference, make current system cannot solve problem for interference.In addition, due to current, airborne TWLU Wireless Data Transmission demand is become increasingly conspicuous, and the wireless service provider disunity on airport, a large amount of wireless device can not unified management, cannot again on existing frequency range carry out good unified planning with reduce wireless device mutually between the impact of interference.

Summary of the invention

The shortcoming of prior art in view of the above, the object of the present invention is to provide a kind of smart antenna equipment, for solve rest in appearance when shelter bridge place carries out radio communication when commercial aircraft in prior art cannot resist co-channel interference, cause accessing difficulty during the TWLU equipment work of aircraft, transfer of data is unstable, the problem that throughput is low.

For achieving the above object and other relevant objects, the invention provides a kind of smart antenna equipment based on IEEE802.11g agreement, described smart antenna equipment comprises Intelligent treatment device, described Intelligent treatment device comprises D/A converter module, self-adaptive processing module, weighted sum module, wherein: described D/A converter module carries out analog-to-digital conversion process, output multi-channel digital signal for receiving multichannel analog signals; Described self-adaptive processing module is connected with D/A converter module, for passing through, the long training sequence signal finding IEEE802.11g agreement is processed further to described multiply digital signals, using described long training sequence signal as reference signal, application of beam shaping Algorithm obtains weights; Described weighted sum module is connected with described D/A converter module and self-adaptive processing module, for according to described weights to described multiply digital signals weighted sum.

Preferably, described smart antenna equipment also comprises multiple signals receiving system, and described multiple signals receiving system receives multi-channel rf signal, and converts multichannel analog signals to.

Preferably, described multiple signals receiving system comprises aerial array and radio-frequency front-end; Wherein: described aerial array, multiple antenna is comprised; Described radio-frequency front-end, comprise the radio-frequency front-end plank that polylith supports IEEE802.11g agreement, the number of described radio-frequency front-end plank is identical with the number of antennas of described aerial array, described radio-frequency front-end plank is connected with described antenna respectively, for receiving the radiofrequency signal on described antenna, and described radiofrequency signal is converted to analog signal.

Preferably, described linear array antenna comprises many omnidirectional antennas of linearly formula arrangement.

The present invention also provides a kind of signal processing method based on IEEE802.11g agreement, and described signal processing method comprises the following steps: step one, receives multiply digital signals; Step 2, finds the long training sequence signal of IEEE802.11g agreement from described multiply digital signals; Step 3, using described long training sequence signal as reference signal, application of beam shaping Algorithm obtains weights; Step 4, utilizes described weights to be weighted summation process to described multiply digital signals.

Preferably, described step one comprises and goes direct current biasing process to multiply digital signals.

Preferably, described step 2 finds by carrying out synchronous process to the long training sequence signal of described IEEE802.11g agreement.

Preferably, described step 2 comprises and carries out low-pass filtering and up-sampling process to multiply digital signals.

Preferably, the described beamforming algorithm in described step 3 comprises the beamforming algorithm following least square criterion.

Preferably, the described beamforming algorithm in described step 3 comprises least mean square algorithm

As mentioned above, a kind of intelligent antenna equipment based on IEEE802.11g agreement of the present invention and signal processing method, for solving the problem be easily disturbed airborne wireless transmission equipment to carry out wireless signal transmission during on airport, there is following beneficial effect: under the condition not changing existing IEEE802.11a/g/n agreement, by multi-antenna technology, airspace filter is realized to the signal weighting summation that its each array element accepts, reach the object strengthening desired signal and suppress to disturb simultaneously, thus finally improve channel capacity, improve speed and reduce the error rate.The present invention is not limited only to shelter bridge place, airport and uses, and is also applicable to the Wireless Data Transmission that other have a large amount of interference to exist.

Accompanying drawing explanation

Fig. 1 is shown as IEEE802.11g protocol frame structure of the prior art and targeting sequencing frame structure schematic diagram

Fig. 2 is shown as the structural representation of a kind of smart antenna equipment based on IEEE802.11g agreement of the present invention.

Fig. 3 is shown as the flow chart of steps of a kind of signal processing method based on IEEE802.11g agreement of the present invention.

Element numbers explanation

1 smart antenna equipment

11 multiple signals receiving systems

111 aerial arrays

112 radio-frequency front-ends

12 Intelligent treatment devices

121 D/A converter modules

122 self-adaptive processing modules

123 weighted sum modules

S1 ~ S4 step

Embodiment

Below by way of specific instantiation, embodiments of the present invention are described, those skilled in the art the content disclosed by this specification can understand other advantages of the present invention and effect easily.The present invention can also be implemented or be applied by embodiments different in addition, and the every details in this specification also can based on different viewpoints and application, carries out various modification or change not deviating under spirit of the present invention.It should be noted that, when not conflicting, the feature in following examples and embodiment can combine mutually.

It should be noted that, the diagram provided in following examples only illustrates basic conception of the present invention in a schematic way, then only the assembly relevant with the present invention is shown in graphic but not component count, shape and size when implementing according to reality is drawn, it is actual when implementing, and the kenel of each assembly, quantity and ratio can be a kind of change arbitrarily, and its assembly layout kenel also may be more complicated.

Refer to Fig. 2, the invention provides a kind of smart antenna equipment 1 based on IEEE802.11g agreement, described smart antenna equipment 1 comprises Intelligent treatment device 12, and described Intelligent treatment device comprises D/A converter module 121, self-adaptive processing module 122, weighted sum module 123.

Described D/A converter module 121, carries out analog-to-digital conversion process, output multi-channel digital signal for receiving multichannel analog signals.Particularly, described D/A converter module 121, after carrying out analog-to-digital conversion process to reception multichannel analog signals, is also gone direct current biasing process to the multiply digital signals after conversion, is exported the multiply digital signals through past direct current biasing process.

Self-adaptive processing module 122, be connected with D/A converter module 121, process to described multiply digital signals the long training sequence signal finding IEEE802.11g agreement for passing through further, using described long training sequence signal as reference signal, application of beam shaping Algorithm obtains weights.Particularly, the multiply digital signals that self-adaptive processing module 122 logarithmic mode modular converter 121 exports processes, and described process comprises low-pass filtering treatment to described multiply digital signals and up-sampling process; Described process also comprises the synchronous process of the long training sequence signal to the IEEE802.11g protocol frame in multiply digital signals, after finding described long training sequence signal, using described long training sequence signal as reference signal, application of beam shaping Algorithm obtains weights.

Weighted sum module 123, is connected with described D/A converter module 121 and described self-adaptive processing module 122, for exporting the digital signal after described multiply digital signals weighted sum according to described weights.The multiply digital signals of described D/A converter module 121 is first stored in FIFO by described weighted sum module 123, after described self-adaptive processing module 122 obtains weights, the weights on required each road are weighted in FIFO output signal, and the summation of the signal of institute's weighting is exported.

Described smart antenna equipment 1 also comprises multiple signals receiving system 11, and described multiple signals receiving system 11 receives multi-channel rf signal, and converts multichannel analog signals to.Particularly, described multiple signals receiving system comprises aerial array 111 and radio-frequency front-end 112.

Described aerial array 111, comprises multiple antenna.Further, described aerial array 111 comprises many omnidirectional antennas of linearly formula arrangement.

Described radio-frequency front-end 112, comprise the radio-frequency front-end plank that polylith supports IEEE802.11g agreement, the number of described radio-frequency front-end plank is identical with the number of antennas of described aerial array, described radio-frequency front-end plank is connected with described antenna respectively, for receiving the radiofrequency signal on described antenna, and described radiofrequency signal is converted to analog signal.Described multi-channel rf signal is TWLU(Terminal Wireless LAN Unit) radio transmission apparatus send signal.Further, described radio-frequency front-end 112 comprises the polylith radio-frequency front-end plank of the many omnidirectional antennas be connected respectively in aerial array, described radio-frequency front-end all needs to support IEEE802.11g agreement, and the radio frequency signal that can realize antenna receives converts Analog Baseband IQ two paths of signals to.Described polylith radio-frequency front-end plank uses same external clock as clock source.The multichannel analog signals of described polylith radio-frequency front-end plank all outputs to described Intelligent treatment device.

Refer to Fig. 3, the present invention also provides a kind of signal processing method based on IEEE802.11g agreement, and described signal processing method can using based in the smart antenna equipment of IEEE802.11g agreement shown in Fig. 2.In execution mode particularly, described intelligent wireless communication equipment includes but not limited to the wireless device at shelter bridge place, airport, also can be applicable in the wireless device of other application IEEE802.11g agreement.Described signal processing method comprises the following steps:

First perform step S1, receive multiply digital signals.Particularly, the multiply digital signals of described reception can be the multiply digital signals that the process of multiple signals receiving system obtains.Further, can all go direct current biasing process to each road signal of described multiply digital signals, DC-offset correction is on the impact of described digital signal.Finally described multiply digital signals is copied into two-way, a road is stored in the internal memory of FIFO, for step S4; Another road is for step S2.Then step S2 is performed.

In step s 2, from described multiply digital signals, find the long training sequence signal of IEEE802.11g agreement.The described long training sequence signal of IEEE802.11g agreement that finds from described multiply digital signals finds by carrying out synchronous process to the long training sequence signal of described IEEE802.11g agreement.Particularly, usually first low-pass filtering treatment and up-sampling process are carried out to described multiply digital signals, and then therefrom find the long training sequence signal of IEEE802.11g agreement.Low-pass filtering treatment is a kind of filter type, rule for low frequency signal can be normal through, exceed the high-frequency signal setting critical value and be then blocked, weaken.Up-sampling carries out resampling to digital signal, namely to carry out resampling higher than original digital signal sample rate to original signal.Then step S3 is performed.

In step s3, using described long training sequence signal as reference signal, application of beam shaping Algorithm obtains weights.Particularly, according to long training sequence (T1 ~ T2) the changeless feature of PLCP in IEEE802.11g agreement, using described long training sequence signal as reference signal, application of beam shaping Algorithm obtains weights, and weights are also referred to as weight vector.Beamforming algorithm is derived according to certain optiaml ciriterion, and conventional criterion has: minimum mean square error criterion, criterion of least squares, maximum signal noise ratio principle and linearly constrained minimum variance etc.Particularly, the beamforming algorithm that described beamforming algorithm is derived according to minimum mean square error criterion, the advantage adopting minimum mean square error criterion is that adaptive surface is wider.Minimum mean square error criterion refers to by finding weight w=[w ₁, w ₂..., w _n] ^tmake the output signal after Received signal strength weighted sum and desired signal mean error minimum:

$\underset{w}{\min }E\left[{|y\left(k\right)-d\left(k\right)|}^2\right]=\underset{w}{\min }E\left[{|w^{H}x\left(k\right)-d\left(k\right)|}^2\right]$

Obtain:

$w=R_x^{-1}{r}_{\mathrm{xd}}$

Wherein, represent with W to be that variable is minimized, E [] is for asking desired value computing; K is natural number, and be expressed as a kth sampled point, y (k) represents the output signal after Received signal strength weighted sum; D (k) represents and expects Received signal strength, i.e. the value of the long training sequence (T1 ~ T2) of PLCP in IEEE802.11g agreement; X (k) represents the multichannel supplied with digital signal received; w ^hrepresent and conjugate transpose is got to w.R _x=E [x (k) x ^h(k)] be the autocorrelation matrix of vector x (k), r _xdthe cross-correlation vector of x (k) and desired signal d (k): r _xd=E [x (k) d ^h(k)],

Least-mean-square error algorithm due to standard needs matrix inversion, and become when wireless transmission environments is, therefore in order to keep intelligent antenna technology timely and effective, weight vector w needs to keep constantly upgrading, and is namely all calculated by PLCP long training sequence (T1 ~ T2) after each frame receives signal and upgrades weight vector w.In order to reduce operand, the approximate solution of weight vector w when using lowest mean square (LMS) algorithm can try to achieve corresponding k sampled point as follows:

$y\left(k\right)={\hat{w}}^H\left(k\right)x\left(k\right),$

e(k)=d(k)-y(k)，

$\hat{w}(k+1)=\hat{w}\left(k\right)+\mathrm{\μx}\left(k\right)e^{*}\left(k\right),$

Wherein, y (k) represents the output signal after weighted sum to received signal; X (k) represents the multichannel supplied with digital signal received; D (k) represents and expects Received signal strength, i.e. the value of the long training sequence (T1 ~ T2) of PLCP in IEEE802.11g agreement; E (k) represents output signal and expects the error between Received signal strength; e ^*k () is expressed as the conjugation of e (k); μ is that convergence factor can be middle arbitrary value, λ _maxfor R _xeigenvalue of maximum.

Assuming that described multiply digital signals is 4 railway digital signals:

X(k)=[x ₁(k),x ₂(k),x ₃(k),x ₄(k)] ^T，

If during k=1, $\hat{w}\left(1\right)={[{\hat{w}}_1\left(1\right),{\hat{w}}_2\left(1\right),...,{\hat{w}}_4\left(1\right)]}^T$ (during actual operation its initial value can be set to [1,1 ..., 1] ^t), 4 road signals are sued for peace respectively with after the conjugate product of corresponding weights, obtains combined signal y (1), ask poor with known sequence d (1) and y (1) afterwards, obtain error e (1).So just can obtain as k=2, approximate solution:

${\hat{w}}_1\left(2\right)={\hat{w}}_1\left(1\right)+{\mathrm{\μx}}_1\left(1\right)e^{*}\left(1\right),{\hat{w}}_2\left(2\right)={\hat{w}}_2\left(1\right)+{\mathrm{\μx}}_2\left(1\right)e^{*}\left(1\right),$

Can obtain equally rule continuation iteration finally can obtain (interative computation number of times is the length K expecting signal sampling) successively:

$\hat{w}\left(K\right)={[{\hat{w}}_1\left(K\right),{\hat{w}}_2\left(K\right),...,{\hat{w}}_4\left(K\right)]}^T$

After obtaining weights, it can be used as the weight w of present frame and perform step S4, until next frame recalculates new weights after arriving.

In step S4, described weights are utilized to be weighted summation process to described multiply digital signals.Particularly, suppose there is N railway digital signal, then final result output signal y (k) is each road input signal x _n(k) and corresponding road weight w _nconjugate product again gained N road result of product is sued for peace.

In sum, a kind of intelligent antenna equipment based on IEEE802.11g agreement of the present invention and signal processing method, the problem be easily disturbed when to carry out wireless signal transmission on airport for airborne wireless transmission equipment, can under the condition not changing existing IEEE802.11a/g/n agreement, by multi-antenna technology, airspace filter is realized to the signal weighting summation that its each array element accepts, reach the object strengthening desired signal and suppress to disturb simultaneously, thus finally improve channel capacity, improve speed and reduce the error rate.Technology of the present invention is compatible IEEE802.11a agreement and IEEE802.11n agreement at present also.The present invention is not limited only to shelter bridge place, airport and uses, and is also applicable to the Wireless Data Transmission that other have a large amount of interference to exist.So the present invention effectively overcomes various shortcoming of the prior art and tool high industrial utilization.

Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not for limiting the present invention.Any person skilled in the art scholar all without prejudice under spirit of the present invention and category, can modify above-described embodiment or changes.Therefore, such as have in art usually know the knowledgeable do not depart from complete under disclosed spirit and technological thought all equivalence modify or change, must be contained by claim of the present invention.

Claims (10)

1. based on a smart antenna equipment for IEEE802.11g agreement, it is characterized in that, described smart antenna equipment comprises Intelligent treatment device, and described Intelligent treatment device comprises:

D/A converter module, carries out analog-to-digital conversion process, output multi-channel digital signal for receiving multichannel analog signals;

Self-adaptive processing module, be connected with D/A converter module, process to described multiply digital signals the long training sequence signal finding IEEE802.11g agreement for passing through further, using described long training sequence signal as reference signal, application of beam shaping Algorithm obtains weights;

Weighted sum module, is connected with described D/A converter module and self-adaptive processing module, for according to described weights to described multiply digital signals weighted sum.

2. the smart antenna equipment based on IEEE802.11g agreement according to claim 1, it is characterized in that: described smart antenna equipment also comprises multiple signals receiving system, described multiple signals receiving system receives multi-channel rf signal, and converts multichannel analog signals to.

3. the smart antenna equipment based on IEEE802.11g agreement according to claim 2, is characterized in that: described multiple signals receiving system comprises:

Described aerial array, comprises multiple antenna;

Described radio-frequency front-end, comprises the radio-frequency front-end plank that polylith supports IEEE802.11g agreement; The number of described radio-frequency front-end plank is identical with the number of antennas of described aerial array; Described radio-frequency front-end plank is connected with described antenna respectively, for receiving the radiofrequency signal on described antenna, and described radiofrequency signal is converted to analog signal.

4. the smart antenna equipment based on IEEE802.11g agreement according to claim 3, is characterized in that: described aerial array comprises many omnidirectional antennas of linearly formula arrangement.

5. based on a signal processing method for IEEE802.11g agreement, it is characterized in that, described signal processing method comprises the following steps:

Step one, receives multiply digital signals;

Step 2, finds the long training sequence signal of IEEE802.11g agreement from described multiply digital signals;

Step 3, using described long training sequence signal as reference signal, application of beam shaping Algorithm obtains weights;

Step 4, utilizes described weights to be weighted summation process to described multiply digital signals.

6. the signal processing method based on IEEE802.11g agreement according to claim 5, is characterized in that: described step one also comprises goes direct current biasing process to described multiply digital signals.

7. the signal processing method based on IEEE802.11g agreement according to claim 5, is characterized in that: described step 2 finds by carrying out synchronous process to the long training sequence signal of described IEEE802.11g agreement.

8. the signal processing method based on IEEE802.11g agreement according to claim 5, is characterized in that: described step 2 comprises low-pass filtering to described multiply digital signals and up-sampling process.

9. the signal processing method based on IEEE802.11g agreement according to claim 5, is characterized in that: the described beamforming algorithm in described step 3 comprises the beamforming algorithm following least square criterion.

10. the signal processing method based on IEEE802.11g agreement according to claim 9, is characterized in that: the described beamforming algorithm in described step 3 comprises least mean square algorithm.