CN104767565A - Multiple-input Multiple-output (MIMO) light communication method, MIMO light communication device and MIMO light communication system - Google Patents

Abstract

The invention discloses a Multiple-input Multiple-output (MIMO) light communication method, an MIMO light communication device and an MIMO light communication system. A transmission signal to be transmitted is modulated to light carriers with different spectral characteristics, so that a light modulation signal is generated and transmitted.

Description

A kind of MIMO optical communication method, device and system

Technical field

The present invention relates to optical communication field, especially a kind of multiple-input and multiple-output (Multiple-InputMultiple-Output, MIMO) optical communication method, device and system.

Background technology

Visible light communication (Visible Light Communications, VLC) is a kind of wireless communication technology, and it utilizes the visible ray of wavelength between 380nm to 780nm to complete the transmission of information as communication medium.In order to improve message capacity, generally adopt frequency division multiplexing or wavelength-division multiplex technique at present.Compared with communicating with single wavelength, wavelength-division multiplex technique adopts multi-band transmission signal, and the light of each wavelength can transmit different signals respectively as independently signal vehicle, thus greatly improves message capacity.In common visible light communication system, receiving terminal receives the effect of data and the performance of receiver and position thereof much relations, and this just means will design complicated, specific physical system.

MIMO Radio Transmission Technology is that an important technology of the communications field is broken through, and it can improve capacity and the spectrum efficiency of wireless communication system exponentially when not increasing bandwidth and power.MIMO space multiplexing technique sends independently data flow on different transmit antennas, to obtain high speed data transfer, to be one of key technology in new generation of wireless communication system, to have caused the extensive concern of people in recent years.

But, MIMO space multiplexing technique increases number of transmit antennas to improve throughput, this too increases the power loss of transmitter undoubtedly, lot of domestic and foreign scholar also proposes the concept of MIMO wavelength division multiplexing one after another for this reason, and object is that the bandwidth availability ratio by improving single transmitting antenna realizes also improving now limited number of transmit antennas the object of data rate.

At present, the key for the MIMO wavelength-division multiplex technique of VLC is how wide light source bandwidth is leached narrow light belt, and in different light belt modulate information, but technical support unripe at present.

Summary of the invention

In view of this, the invention provides a kind of MIMO optical communication method, device and system, combine with spatial reuse to realize wavelength division multiplexing.

Technical scheme of the present invention is achieved in that

A kind of MIMO optical communication method, the method comprises:

The signal transmission that will send be modulated to there is different spectral characteristic light carrier on, generate light modulating signal and also launch.

A kind of MIMO optical communication method, the method comprises:

Receive light modulating signal, utilize the channel transfer matrices of MIMO optical communication system, restore signal transmission.

Before carrying out described recovery, also comprise: set up described channel transfer matrices by Signal reception test.

A kind of MIMO optical communication apparatus, as optical signal launch end; The intensity modulation module that described device comprises n optical transmitting set and is connected with a described n optical transmitting set; Wherein,

The light that each optical transmitting set is launched has different spectral characteristics;

The light carrier that described intensity modulation module is launched for signal transmission being modulated to each optical transmitting set, generates light modulating signal;

Described n be greater than 1 integer.

A described n optical transmitting set is the different narrow-band light source of n output wavelength.

Described optical transmitting set is the wideband light source that surface attachment has filter layer, and the wavelength of the filter layer institute transmitted light of each wideband light source is different.

A kind of MIMO optical communication apparatus, as light signal receiving terminal; Described device comprises m the photodetector each other with different spectral characteristic and the signal processing unit be connected with a described m photodetector; Wherein,

Described signal processing unit is used for the light modulating signal detected according to described photodetector, utilizes the channel transfer matrices of MIMO optical communication system, restores signal transmission;

Described m be greater than 1 integer.

Described m the photodetector each other with different spectral characteristic is realized by the filter layer arranging the light of transmissive different wave length on the receiving terminal surface of the individual identical photo-detector of m respectively.

A kind of MIMO optical communication system, described system comprises optical signal launch end and light signal receiving terminal; Wherein,

Described optical signal launch end, the signal transmission for sending is modulated to the light carrier with different spectral characteristic, generates light modulating signal and launches;

Described light signal receiving terminal, for receiving light modulating signal, utilizing the channel transfer matrices of MIMO optical communication system, restoring signal transmission.

The intensity modulation module that described optical signal launch end comprises n optical transmitting set and is connected with a described n optical transmitting set; Wherein,

The light that each optical transmitting set is launched has different spectral characteristics;

The light carrier that described intensity modulation module is launched for signal transmission being modulated to each optical transmitting set, generates light modulating signal;

Described light signal receiving terminal comprises m the photodetector each other with different spectral characteristic and the signal processing unit be connected with a described m photodetector; Wherein,

Described signal processing unit is used for the light modulating signal detected according to described photodetector, utilizes the channel transfer matrices of MIMO optical communication system, restores signal transmission;

Described n, m are the integer being greater than 1.

Present invention achieves wavelength division multiplexing to combine with spatial reuse.

Accompanying drawing explanation

Fig. 1 is the principle schematic of MIMO optical communication system of the present invention;

Fig. 2 is the structural representation of MIMO optical communication system in the embodiment of the present invention;

Fig. 3-1 is light-emitting diode (LED) the array schematic diagram transmitted in the embodiment of the present invention as " 1000 ";

Fig. 3-2 is the LED array schematic diagram transmitted in the embodiment of the present invention as " 0100 ";

Fig. 3-3 is the LED array schematic diagram transmitted in the embodiment of the present invention as " 0010 ";

Fig. 3-4 is the LED array schematic diagram transmitted in the embodiment of the present invention as " 0001 ";

Fig. 4 is the LED array schematic diagram transmitted in the embodiment of the present invention as " 0101 ";

Fig. 5 is the MIMO optical communication general flow chart of the embodiment of the present invention;

Description of reference numerals:

1, light emitter arrays; 2, optical receiver array; 3, channel; 4, red LED; 5, yellow led; 6, green LED; 7, blue led; 8, No. 1 photo-detector; 9, No. 2 photo-detectors; 10, No. 3 photo-detectors; 11, No. 4 photo-detectors.

Embodiment

In general, MIMO optical communication system of the present invention, comprise optical signal launch end and light signal receiving terminal, the intensity modulation module that described optical signal launch end comprises n optical transmitting set and is connected with a described n optical transmitting set, the light that each optical transmitting set is launched has different spectral characteristics, signal transmission is modulated on the light carrier that each optical transmitting set launches by intensity modulation module, generates light modulating signal, is emitted to free space; Described light signal receiving terminal comprises m the photodetector each other with different spectral characteristic and the signal processing unit be connected with a described m photodetector, the light modulating signal that signal processing unit detects according to m photodetector, utilize the channel transfer matrices of described MIMO optical communication system, restore signal transmission; Wherein n, m are the integer being greater than 1.

A described n optical transmitting set can be the different narrow-band light source of n output wavelength.Realize cost to reduce, the preferred following technical scheme of the present invention: described optical transmitting set is the wideband light source that surface attachment has filter layer, the wavelength of the filter layer institute transmitted light of each wideband light source is different.The wave-length coverage of the light of these filter layer institute transmissions can be overlapping, also can non-overlapping copies.

Preferably, described m the photodetector each other with different spectral characteristic is realized by the filter layer arranging the light of transmissive different wave length on the receiving terminal surface of the individual identical photo-detector of m respectively.

Below in conjunction with accompanying drawing, technical scheme of the present invention is described in detail:

Fig. 1 is the principle schematic of MIMO optical communication system of the present invention, as shown in the figure, this system comprises optical signal launch end and light signal receiving terminal, optical signal launch end comprises the light that light emitter arrays 1, n optical transmitting set of being made up of n optical transmitting set launches and has mutually different spectral characteristic; The spectral characteristic that light signal receiving terminal comprises optical receiver array 2, m the photo-detectors be made up of m photo-detector is different.The channel that a bars is transmitted is formed between every a pair optical transmitting set and photo-detector.Light emitter arrays 1 can be made up of the narrow-band light source that n output wavelength is different; Or be made up of n wideband light source, each wideband light source surface attachment has one deck filter layer, the light of filter layer to different wave length of each wideband light source has different transmissivities, and the wave-length coverage of the light of these filtering film institute transmissions can be overlapping, also can non-overlapping copies.Optical receiver array 2 also can be made up of the photo-detector that m spectral characteristic is different, also can be realized by the filter layer arranging the light of transmissive different wave length on the receiving terminal surface of m identical photo-detector respectively.Filter layer of the present invention can adopt polytype, as filter coating, anti-reflection film, optical color film etc.The optical color polyester film that the present invention preferably utilizes microwave dyeing method to prepare, this thin film preparation process is easy, stable.Only coloring agent specific wavelength to absorption characteristic need be selected as requested to carry out painted, just can obtain required filter layer different wave length to different transmissivity.

Intensity modulation module adopts light intensity modulation mode, the signal launched by light emitter arrays 1 carries out distinguishing (such as " luminous intensity is larger " representation signal " 1 ", " luminous intensity is less or not luminous " representation signal " 0 ") with the intensity size of light, and the light signal after modulation transfers to optical receiver array 2 by channel 3.Each photo-detector in optical receiver array 2 is by received optical signal transmission to signal processing unit, and signal processing unit, according to channel transfer matrices, restores the signal transmission that optical signals transmitting terminal sends.

Below the operation principle of the MIMO communication system of the embodiment of the present invention and the course of work are briefly introduced.

Suppose that the number of optical transmitting set in the light emitter arrays of MIMO communication system of the present invention is n, photodetector number in optical receiver array is m, and n the light intensity signal (" luminous intensity is larger " representation signal " 1 ", " luminous intensity is less or not luminous " representation signal " 0 ") sent by a certain moment light emitter arrays is as unknown data x _n, namely a light intensity signal (non-1 that is 0) launched by optical transmitting set, then x _nfor the one-dimensional vector containing n element.The m data optical receiver array detection posting different wave filtering layer arrived is as reception data y _m, y _mfor the one-dimensional vector containing m element.

Suppose that channel transfer matrices is H, then H is the matrix of m × n dimension, each element in this channel transfer matrices is the signal attenuation value between optical receiver and optical transmitting set, and namely the signal of all optical transmitting sets that receives of optical receiver, finally adopts the mode of direct-detection to carry out demodulation.When life's work, obtain channel transfer matrices H by test.

The concrete testing procedure of channel transfer matrices H is:

Optical signal launch end lights separately each optical transmitting set (i.e. " luminous intensity is larger " representation signal " 1 ") successively, while lighting an optical transmitting set, other optical transmitting sets are all in closed condition (i.e. " luminous intensity is less or not luminous " representation signal " 0 ");

Signal processing unit records each optical transmitting set respectively when lighting separately, the data detected by optical receiver array, and sets up channel transfer matrices H according to these data.When namely being transmitted by calculating i-th optical transmitting set, the light intensity value that m optical receiver receives, is designated as H respectively _1i, H _2i..., H _mi, i=1,2 ..., n, sets up the i-th row of H matrix, thus obtains H matrix:

$H=\left[\begin{array}{cccc}{H}_{11}& H_{12}& ...& H_{1n}\\ H_{21}& H_{22}& ...& H_{2n}\\ ...& & ...& \\ H_{m1}& H_{m2}& ...& H_{\mathrm{mn}}\end{array}\right]$

Send data x _nafter the decay of channel H, the data received are y _m, then y is had _m=Hx _n.

Suppose that H-1 is the inverse matrix of H, the estimated value of initial data can calculate by receiving data, i.e. x' _n=H ^-1y _m.

Because the numerical value of the channel transfer matrices in above-mentioned equation group is inaccurate, there is certain measure error, therefore when n is larger, above-mentioned equation group likely becomes ill-conditioned linear systems.In this case, this system of linear equations can be solved better with Tikhonov regularization method.Due to x _n' be by measured value y _nthe estimated value calculated, needs x _n' compare judgement, as adopted mean value method, thus draw the n road original binary signal of certain moment light transmitting terminal.Measured fast continuously by optical receiver array, signal processing calculates judgement continuously fast, just can recover to obtain the original binary signal that not light emitters transmitted in each moment.

For ease of understanding technical solution of the present invention, with specific embodiment, the present invention will be described below.

As shown in Figure 2, the light transmitting terminal array of the present embodiment is made up of the LED of 4 different colours, is respectively red LED, yellow led, green LED and blue led.Each LED sends the signal of different wave length, and this signal adopts light intensity modulation mode to carry out distinguishing (" luminous intensity is larger " representation signal " 1 ", " luminous intensity is less or not luminous " representation signal " 0 ") with light emitted intensity size.Optical receiver array is made up of 4 photo-detectors (as PIN photoelectric detector), different filtering films is all posted before each photo-detector, be designated as respectively: filtering film 1, filtering film 2, filtering film 3 and filtering film 4, these four filtering films are different, and its difference is there is different transmissivities to the light of different wave length.

The response current produced due to photo-detector is general very faint, is not easy to direct-detection.Therefore can access treatment circuit after optical receiver array, the signal that namely photodetector of receiving terminal detects is through the magnitude of voltage after processing of circuit.

Before life's work starts, can obtain channel transfer matrices H by test in advance, concrete test process is as follows:

Signal transmitting terminal lights separately the LED of a certain color successively, and send signal " 1 ", while lighting a LED, other LED are all in closed condition, all send signal " 0 ";

Record all data that when each LED lights separately, photodetector detects respectively, and set up channel transfer matrices H according to these data, when namely being transmitted by calculating i-th reflector, the light intensity value that 4 receivers receive is designated as H respectively _1i, H _2i, H _3i, H _4i, i=1,2,3,4, set up the i-th row of H matrix; The value that a corresponding jth detector detects for 4 times is respectively H _j1, H _j2, H _j3, H _j4, j=1,2,3,4, i.e. the jth row of H matrix, thus obtain H matrix:

$H=\left[\begin{array}{cccc}{H}_{11}& H_{12}& H_{13}& H_{14}\\ H_{21}& H_{22}& H_{23}& H_{24}\\ H_{31}& H_{32}& H_{33}& H_{34}\\ H_{41}& H_{42}& H_{43}& H_{44}\end{array}\right]$

Fig. 3-1, Fig. 3-2, Fig. 3-3, Fig. 3-4 are respectively the LED array schematic diagram transmitted as " 1000 ", " 0100 ", " 0010 ", " 0001 ", namely red, yellow, green, blue led is distinguished bright, shade representative " luminous intensity is larger "-" 1 " in figure, white representative " luminous intensity is less or not luminous "---" 0 ".Specifically, in Fig. 3-1, only red LED is bright, shade representative " luminous intensity is larger "-" 1 " in figure, white representative " luminous intensity is less or not luminous "-" 0 "; In Fig. 3-2, only yellow led is bright, shade representative " luminous intensity is larger "-" 1 " in figure, white representative " luminous intensity is less or not luminous "-" 0 "; In Fig. 3-3, only green LED is bright, shade representative " luminous intensity is larger "-" 1 " in figure, white representative " luminous intensity is less or not luminous "-" 0 "; In Fig. 3-4, only blue led is bright, shade representative " luminous intensity is larger "-" 1 " in figure, white representative " luminous intensity is less or not luminous "-" 0 ".

In the present embodiment, the supply power voltage of transmitting terminal LED array is 3.0V, and the reception and transmission range of setting is 21.0cm, gathers response data, thus obtain H matrix by the response of lighting separately every paths of LEDs lamp.In experiment, due to zero noise circumstance cannot be accomplished, therefore in order to the residual quantity between measures of quantization data and noise data, take absolute value the difference of measurement data and noise data (namely all LED close the data that time receiver array detects) as final reception data, experimental data is as follows:

The data collected when table 1, transmitting information " 1000 "

The data collected when table 2, transmitting information " 0100 "

The data collected when table 3, transmitting information " 0010 "

The data collected when table 4, transmitting information " 0001 "

Visible, H _j1=[H ₁₁h ₂₁h ₃₁h ₄₁] ^t=[0.080.0680.2480.53] ^t, H _j2=[H ₁₂h ₂₂h ₃₂h ₄₂] ^t=[0.190.3420.2580.67] ^t, H _j3=[H ₁₃h ₂₃h ₃₃h ₄₃] ^t=[0.131.9520.2230.41] ^t, H _j4=[H ₁₄h ₂₄h ₃₄h ₄₄] ^t=[0.291.4422.2320.66] ^t.

So obtain H matrix:

$H=\left[\begin{array}{cccc}{H}_{11}& H_{12}& H_{13}& H_{14}\\ H_{21}& H_{22}& H_{23}& H_{24}\\ H_{31}& H_{32}& H_{33}& H_{34}\\ H_{41}& H_{42}& H_{43}& H_{44}\end{array}\right]=\left[\begin{array}{cccc}0.08& 0.19& 0.13& 0.29\\ 0.068& 0.342& 1.952& 1.442\\ 0.248& 0.258& 0.223& 2.232\\ 0.53& 0.67& 0.41& 0.66\end{array}\right]$

H is got inverse:

$H^{-1}=\left[\begin{array}{cccc}-14.044& 0.0851& 0.6826& 3.6763\\ 11.8853& -0.4117& -0.8860& -1.3266\\ -1.8689& 0.5974& -0.2366& 0.3162\\ 0.3733& -0.0216& 0.4982& 0.2867\end{array}\right]$

H ^-1it is the inverse matrix of H.

Just can formally transmit by start information after measurement obtains H matrix in advance.

Fig. 4 LED array schematic diagram that to be transmission one group of random signal be " 0101 ", namely yellow led and blue led simultaneously bright, shade representative " luminous intensity is larger "-" 1 " in figure, white representative " luminous intensity is less or not luminous "-" 0 ".Experimental data is as shown in table 5, and the value that now photodetector detects is designated as y, due to transmitting terminal in the present embodiment and receiving terminal array number less, therefore only common method need be adopted to utilize formula x'=H here ^-1y can solve the estimated value obtaining initial data, then compares judgement to vectorial x', just can recover the primary signal of this moment transmitting terminal.

The data that table 5 collects when launching information " 0101 "

From above experimental data, y _n=y ₄=[1.071.3822.0620.90] ^t, according to formula x' _n=H ^-1y _nx' can be obtained ₄=[-10.19329.1275-1.37751.1390] ^t, thus obtain x _nestimated value, for the sake of simplicity, the present embodiment adopt mean value method compare judgement, get x ₄' the mean value of four elements as decision value, namely getting decision value is-0.33, is greater than this value and is set to " 1 ", is less than this value and is set to " 0 ".Final x ₄' turn to: [0101] ^t, the random data " 0101 " of these data and transmitting fits like a glove.

Visible in conjunction with above description, MIMO optical communication method of the present invention can represent flow process as shown in Figure 5, and this flow process comprises the following steps:

Step 510: the signal transmission that will send be modulated to there is different spectral characteristic light carrier on, generate light modulating signal;

Step 520: launch described light modulating signal.

Visible in sum, no matter be method, device or system, MIMO optical communication technique of the present invention can load unlike signal in Different Light, launches while achieving multiple signals, achieve the combination of wavelength division multiplexing and spatial reuse, significantly improve message capacity and message transmission rate.In addition, the present invention utilizes the wideband light source/photo-detector being easier to obtain to make Different Light launch the light of different wave length in conjunction with filter layer, and different photo-detector receives the light of different wave length, reduces the requirement of light source, achieves the object that broad spectrum light source leaches narrow light belt; Because filter layer makes simple, cheap, therefore the present invention is simple and easy to realize.Visible, the present invention is realizing while wavelength division multiplexing combines with spatial reuse, reducing and realizing cost.

The above, be only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention.

Claims (10)

1. a multiple-input and multiple-output MIMO optical communication method, is characterized in that, the method comprises:

The signal transmission that will send be modulated to there is different spectral characteristic light carrier on, generate light modulating signal and also launch.

2. a MIMO optical communication method, is characterized in that, the method comprises:

Receive light modulating signal, utilize the channel transfer matrices of MIMO optical communication system, restore signal transmission.

3. method according to claim 2, is characterized in that, before carrying out described recovery, also comprises: set up described channel transfer matrices by Signal reception test.

4. a MIMO optical communication apparatus, as optical signal launch end; It is characterized in that, the intensity modulation module that described device comprises n optical transmitting set and is connected with a described n optical transmitting set; Wherein,

The light that each optical transmitting set is launched has different spectral characteristics;

The light carrier that described intensity modulation module is launched for signal transmission being modulated to each optical transmitting set, generates light modulating signal;

Described n be greater than 1 integer.

5. device according to claim 4, is characterized in that, a described n optical transmitting set is the different narrow-band light source of n output wavelength.

6. device according to claim 4, is characterized in that, described optical transmitting set is the wideband light source that surface attachment has filter layer, and the wavelength of the filter layer institute transmitted light of each wideband light source is different.

7. a MIMO optical communication apparatus, as light signal receiving terminal; It is characterized in that, described device comprises m the photodetector each other with different spectral characteristic and the signal processing unit be connected with a described m photodetector; Wherein,

Described signal processing unit is used for the light modulating signal detected according to described photodetector, utilizes the channel transfer matrices of MIMO optical communication system, restores signal transmission;

Described m be greater than 1 integer.

8. device according to claim 7, is characterized in that,

Described m the photodetector each other with different spectral characteristic is realized by the filter layer arranging the light of transmissive different wave length on the receiving terminal surface of the individual identical photo-detector of m respectively.

9. a MIMO optical communication system, is characterized in that, described system comprises optical signal launch end and light signal receiving terminal; Wherein,

Described optical signal launch end, the signal transmission for sending is modulated to the light carrier with different spectral characteristic, generates light modulating signal and launches;

Described light signal receiving terminal, for receiving light modulating signal, utilizing the channel transfer matrices of MIMO optical communication system, restoring signal transmission.

10. system according to claim 9, is characterized in that,

The intensity modulation module that described optical signal launch end comprises n optical transmitting set and is connected with a described n optical transmitting set; Wherein,

The light that each optical transmitting set is launched has different spectral characteristics;

The light carrier that described intensity modulation module is launched for signal transmission being modulated to each optical transmitting set, generates light modulating signal;

Described light signal receiving terminal comprises m the photodetector each other with different spectral characteristic and the signal processing unit be connected with a described m photodetector; Wherein,

Described signal processing unit is used for the light modulating signal detected according to described photodetector, utilizes the channel transfer matrices of MIMO optical communication system, restores signal transmission;

Described n, m are the integer being greater than 1.