CN104243033B - A kind of spatial modulation launching technique being applicable to visible light communication - Google Patents

Abstract

The invention belongs to indoor visible light communication technical field, particularly to a kind of spatial modulation launching technique being applicable to visible light communication.For current visible ray spatial modulation being difficult to take into account communication system bit error rate performance and the problem of room lighting effect, the present invention is by suitably choosing the half-power angle of each LED signal transmitter in visible ray spatial modulation, under conditions of ensureing communication system bit error rate performance, effectively improve the lighting condition of indoor.It is simple that the present invention realizes process, while strengthening visible ray spatial modulation practicality, improves the motility of spatial modulation further.

Description

A kind of spatial modulation launching technique being applicable to visible light communication

Technical field

The invention belongs to technical field of visible light communication, send out particularly to a kind of spatial modulation being applicable to visible light communication Shooting method.

Background technology

Visible light communication technology has become the study hotspot of the communications field the most.Compared to traditional radio communication skill Art, it is seen that optical communication technique has energy-saving safe, good confidentiality, need not frequency spectrum certification, transfer rate advantages of higher.Visible In optical communication system, light source not only acts as the effect of illumination, can carry out data transmission simultaneously.

Visible ray space-modulation technique is that a kind of novel low complex degree occurred in visible light communication field in recent years is adjusted Technology processed.Its ultimate principle is that the bit information of transmitting is divided into two parts, and a part passes through conventional visible ray modulator approach, Such as OOK, PAM etc., the result that modulation is obtained by another part is mapped on corresponding LED signal transmitter, at same time slot In, only allow a LED signal transmitter in running order, carry transmission by the LED signal transmitter sequence number of work Information.Compared with traditional MIMO technology, space-modulation technique effectively prevent interchannel interference (ICI) and multi-antenna transmission is same Step (IAS) problem, under certain conditions, has certain practical value.

In the visible ray spatial modulation of standard, the LED that generally the multiple parameters of use are identical is as the transmitting of communication system Machine.In this case, choose the less LED of half-power angle as signal transmitter, make the energy of LED emission more concentrate, So that the bit error rate performance of communication system is significantly improved.But, along with each LED signal transmitter half-power angle Reducing, their illuminating effect can significantly be deteriorated, and illumination region diminishes rapidly, is unfavorable for the illumination of indoor.Otherwise, for ensureing to shine Obvious results fruit, selects the LED that half-power angle is bigger as signal transmitter, can cause again visible light communication system bit error rate performance Severe exacerbation.Therefore, the visible ray spatial modulation of standard is difficult to ensure good illuminating effect and reliable communication performance simultaneously.

Summary of the invention

Goal of the invention: in order to overcome the defect of above-mentioned prior art, the invention provides one and be applicable to visible light communication Spatial modulation launching technique, this visible ray modulating method, ensure communication system bit error rate performance on the basis of, Can be in the illumination of indoor offer abundance.

Technical scheme: a kind of spatial modulation launching technique being applicable to visible light communication, it is characterised in that: include that LED believes Number transmitter and PD signal receiver, the method comprises the following steps:

Step 1), in indoor layout N_TIndividual LED signal transmitter and N_RIndividual PD signal receiver；Described LED signal transmitter For LED, PD signal receiver is photodiode；

Wherein: N_T=2^k, k=1,2 ...；

N_R≥2；

Step 2), determine step 1) in the LED signal transmitter that determines and the locus of PD signal receiver, according to sky Between the geometrical relationship of position, under conditions of ensureing communication overlay, calculate each LED signal transmitter respectively to N_RIndividual PD signal The angle of emergence of receiver, each LED signal transmitter can get N_RThe individual angle of emergence；Take described N_RThe minima of the individual angle of emergence is Minimum half-power angle

Step 3), judge step 2) in the minimum half-power angle of each LED transmitter of gainedWhether it is respectively less than 80 degree, if It is respectively less than 80 degree, then chooses wherein any one LED signal transmitter, by step 2) obtain its minimum half-power angleBy it Half-power angle is set asMeet:To remaining (N_T-1) half-power of individual LED signal transmitter Angle is all set as respective minimum half-power angle；

If there being the minimum half-power angle of any one LED transmitterMore than 80 degree: then by half merit of each LED transmitter Rate angle is all set as minimum half-power angle

Step 4), after the half-power angle of upper all LED signal transmitters all determines, work according to spatial modulation mode, Carry out indoor visible light communication.

As preferably, step 2) specifically include following steps:

2.1), determine step 1) in the LED signal transmitter that determines and the locus of PD signal receiver:

Set up rectangular coordinate system in space in indoor, determine all LED signal transmitters, the coordinate of PD signal receiver；If N-th_tThe coordinate of individual LED signal transmitter isN-th_rThe coordinate of individual PD signal receiver is $(x_{n_r},y_{n_r},z_{n_r});$

2.2), according to geometrical relationship, each LED signal transmitter angle of emergence φ to all PD signal receivers is calculated, N-th_tIndividual LED signal transmitter is to n-th_rThe angle of emergence of individual PD signal receiver is:

${\mathrm{\φ}}_{n_t{n}_r}=\arccos \left(\frac{z_{n_t}-z_{n_r}}{\sqrt{{(x_{n_t}-x_{n_r})}^2+{(y_{n_t}-y_{n_r})}^2+{(z_{n_t}-z_{n_r})}^2}}\right)$

n_t=1,2 ..., N_T,n_r=1,2 ..., N_R

2.3), n-th_tIndividual LED signal transmitter is respectively as follows: to angle of emergence φ of all PD signal receivers

${\mathrm{\φ}}_{n_{t}1},{\mathrm{\φ}}_{n_{t}2},...,{\mathrm{\φ}}_{n_t{N}_R}$

Take minima therein, be n-th_tThe minimum half-power angle of individual LED transmitter

Wherein, n_t=1,2 ..., N_T。

Beneficial effect:

(1) can need according to actual illumination, select LED that half-power angle is bigger as the transmitting of spatial modulation Machine, expands the illumination zone of visible ray spatial modulation communication system, makes illumination more uniform simultaneously, improves indoor illumination effect Really；

(2) can suitably choose the half-power angle of remaining LED transmitter according to actual communication performance requirement, make LED emission Energy more concentrate, be effectively improved the bit error rate performance of communication system；

(3) in visible ray spatial modulation, the half-power angle of LED transmitter is distinguished by, can provide certain on the whole Diversity gain.

Accompanying drawing explanation

Fig. 1 is the theory diagram of visible ray spatial modulation communication system；

Fig. 2 is the more excellent instance graph of visible ray spatial modulation in the present invention；

Fig. 3 be half-power angle be that the LED light source of 10 degree is at the surface of intensity distribution of room lighting；

Fig. 4 be half-power angle be that the LED light source of 80 degree is at the surface of intensity distribution of room lighting；

Fig. 5 is the graph of a relation in standard visible ray spatial modulation between bit error rate performance and LED transmitter half-power angle；

Fig. 6 is the bit error rate performance comparison diagram of the present invention and standard visible ray spatial modulation；

Detailed description of the invention

Below in conjunction with the accompanying drawings the present invention is further described.

As shown in figures 1 to 6, the present invention discloses a kind of spatial modulation launching technique being applicable to visible light communication, by suitably Choose the half-power angle of LED signal transmitter in spatial modulation, while meeting room lighting demand, it is achieved that reliably lead to Letter, the method realizes simple, specifically comprises the steps of

A kind of spatial modulation launching technique being applicable to visible light communication, it is characterised in that: include LED signal transmitter and PD signal receiver, the method comprises the following steps:

1), in indoor layout N_TIndividual LED signal transmitter and N_RIndividual PD signal receiver；Described LED signal transmitter is LED, PD signal receiver is photodiode；

Wherein: N_T=2^k, k=1,2 ...；

N_R≥2；

2), determine step 1) in the LED signal transmitter that determines and the locus of PD signal receiver, according to space bit The geometrical relationship put, is ensureing under conditions of communication overlay, calculates each LED signal transmitter respectively to N_RIndividual PD signal receives The angle of emergence of machine, each LED signal transmitter can get N_RThe individual angle of emergence；Take described N_RThe minima of the individual angle of emergence is minimum Half-power angle

2.1) determine step 1) in the LED signal transmitter that determines and the locus of PD signal receiver:

Set up rectangular coordinate system in space in indoor, determine all LED signal transmitters, the coordinate of PD signal receiver；If N-th_tThe coordinate of individual LED signal transmitter isN-th_rThe coordinate of individual PD signal receiver is $(x_{n_r},y_{n_r},z_{n_r});$

2.2) according to geometrical relationship, each LED signal transmitter angle of emergence φ to all PD signal receivers is calculated, the n_tIndividual LED signal transmitter is to n-th_rThe angle of emergence of individual PD signal receiver is:

${\mathrm{\φ}}_{n_t{n}_r}=\arccos \left(\frac{z_{n_t}-z_{n_r}}{\sqrt{{(x_{n_t}-x_{n_r})}^2+{(y_{n_t}-y_{n_r})}^2+{(z_{n_t}-z_{n_r})}^2}}\right)$

n_t=1,2 ..., N_T,n_r=1,2 ..., N_R

2.3) n-th_tIndividual LED signal transmitter is respectively as follows: to angle of emergence φ of all PD signal receivers

${\mathrm{\φ}}_{n_{t}1},{\mathrm{\φ}}_{n_{t}2},...,{\mathrm{\φ}}_{n_t{N}_R}$

Take minima therein, be n-th_tThe minimum half-power angle of individual LED transmitter

Wherein, n_t=1,2 ..., N_T。

3), judge step 2) in the minimum half-power angle of each LED transmitter of gainedWhether it is respectively less than 80 degree, if the least In 80 degree, then choose wherein any one LED signal transmitter, by step 2) obtain its minimum half-power angleBy its half merit Rate angle is set asMeet:To remaining (N_T-1) half-power angle of individual LED signal transmitter is equal It is set as respective minimum half-power angle；

If there being the minimum half-power angle of any one LED transmitterMore than 80 degree: then by half merit of each LED transmitter Rate angle is all set as minimum half-power angleTo ensure optimal communication system bit error rate performance.Meanwhile, when communication system error code When rate requires the highest, it is possible to the LED that suitably selection half-power angle is bigger is as signal transmitter, to take into account illuminating effect；

(5) after the half-power angle of above-mentioned all LED signal transmitters all determines, according to the spatial modulation mode work of standard Make, carry out indoor visible light communication, the most both can realize data transmission, room lighting can also be ensured.

The present invention is described further with example below in conjunction with the accompanying drawings.

With reference to shown in Fig. 1, for the theory diagram of visible ray spatial modulation communication system.Information bit channel waiting for transmission After coding, it is transmitted by spatial modulation.In visible ray space-modulation technique, arbitrary time slot only one of which LED signal is sent out Penetrating machine in running order, remaining LED signal transmitter is mourned in silence, and the information bit part after chnnel coding is mapped to traditional On digital modulation planisphere, another part is mapped in the space dimension of LED transmitter serial number gencration.So, LED transmitter sequence number Also carry the transmission of partial information, improve the availability of frequency spectrum of system.At receiving terminal, the signal received is adjusted according to space Optimum Detection in system is demodulated, and finally decoding obtains the data of transmission.

With reference to shown in Fig. 2, the one for visible ray spatial modulation implements, and is also the more excellent example of the present invention, in figure The length, width and height of x, y, z agent's room inner room respectively, TX represents LED signal transmitter, and RX represents PD signal receiver, and φ represents TX To the angle of emergence of RX, ψ represents the angle of incidence of TX to RX.In the room of a 4.0m × 4.0m × 3.0m, it is considered to there is N_T=4 Individual LED transmitter, N_RThe indoor visible light spatial modulation scheme of=4 PD receivers.Consider a kind of tally with the actual situation logical Letter scheme: it is the square of 0.3m that 4 LED transmitter are arranged in a length of side, and this square is placed on height for 2.5m Center, room；It is the square of 0.1m that 4 receivers are arranged in a length of side, and is placed on the height room for 0.75m Center.According to the definition of spatial modulation, at a certain time slot, signal launched by only one of which transmitter, by the transmitting of work The sequence number of machine carrys out transmitted bit information.By LED transmitter and the geometrical relationship of PD receiver, according in step of the present invention (2) Formula is calculated, and the minimum value of 4 LED transmitter half-power angles is 4.62 degree.So, when half merit of 4 LED transmitter When rate angle is about 5 degree, the bit error rate performance of communication system reaches optimal, but the illuminating effect in the most whole room is very poor.Root The method proposed according to the present invention, can replace with half-power by the most any 1 LED transmitter according to actual lighting demand The LED transmitter that angle is bigger, such as half-power angle are 80 degree, ensure that other 3 LED transmitter half-power angles are still 5 degree simultaneously. By simulation result in Fig. 6 it can be seen that now, the lighting demand of indoor can be met, can guarantee that again communication bit error rates performance.

With reference to Fig. 3, shown in 4, the illuminating effect of LED significantly improves greatly along with the change of half-power angle.Fig. 3, in 4, W, L represent The coordinate of each indoor position, the longitudinal axis represents the light intensity of relevant position；When the half-power angle of LED light source is less, such as half Power angle is 10 degree, and the directivity of light source is fine, but illuminating effect is very poor, and only a part of region under just to LED is There is illumination patterns, although the intensity of illumination of this subregion can be higher, but other area light are according to the most weak, even without illumination, Cause there is lighting blind zone；When LED light source half-power angle is bigger, such as half-power angle is 80 degree, and LED light source is to all directions Radiation, and illumination patterns ratio is more uniform, and illuminating effect is preferable.

With reference to shown in Fig. 5, in figure, transverse axis is visible ray spatial modulation communication system transmitting terminal signal to noise ratio, and the longitudinal axis is communication system The bit error rate of system.In the spatial modulation of standard, each LED transmitter half-power angle is identical, permissible from simulation result Finding out, the slight increase of LED transmitter half-power angle, the bit error rate performance that may result in communication system deteriorates rapidly.Therefore, Keeping good communication bit error rates performance, the half-power angle of LED transmitter is unsuitable excessive.

With reference to shown in Fig. 6, in figure, transverse axis is visible ray spatial modulation communication system transmitting terminal signal to noise ratio, and the longitudinal axis is communication system The bit error rate of system.More excellent example bit error rate performance simulation result for the present invention.In figure, result shows, the present invention is significantly changing While kind room lighting, improve the bit error rate performance of visible ray spatial modulation simultaneously.

The above is only the preferred embodiment of the present invention, it should be pointed out that: for the ordinary skill people of the art For Yuan, under the premise without departing from the principles of the invention, it is also possible to make some improvements and modifications, these improvements and modifications also should It is considered as protection scope of the present invention.

Claims (2)

1. the spatial modulation launching technique being applicable to visible light communication, it is characterised in that: include LED signal transmitter and PD Signal receiver, the method comprises the following steps:

1), in indoor layout N_TIndividual LED signal transmitter and N_RIndividual PD signal receiver；Described LED signal transmitter is LED, PD signal receiver is photodiode；

Wherein: N_T=2^k, k=1,2 ...；

N_R≥2；

2), determine step 1) in the LED signal transmitter that determines and the locus of PD signal receiver, according to locus Geometrical relationship, is ensureing under conditions of communication overlay, calculates each LED signal transmitter respectively to N_RIndividual PD signal receiver The angle of emergence, each LED signal transmitter can get N_RThe individual angle of emergence；Take described N_RThe minima of the individual angle of emergence is smaller part merit Rate angle

3), judge step 2) in the minimum half-power angle of each LED transmitter of gainedWhether it is respectively less than 80 degree, if respectively less than 80 Degree, then choose wherein any one LED signal transmitter, by step 2) obtain its minimum half-power angleBy its half-power angle It is set asMeet:To remaining (N_T-1) half-power angle of individual LED signal transmitter all sets For respective minimum half-power angle

4), after the half-power angle of above-mentioned all LED signal transmitters all determines, work according to spatial modulation mode, carry out room Interior visible light communication.

A kind of spatial modulation launching technique being applicable to visible light communication, it is characterised in that: described Step 2) specifically include following steps:

2.1) determine step 1) in the LED signal transmitter that determines and the locus of PD signal receiver:

Set up rectangular coordinate system in space in indoor, determine all LED signal transmitters, the coordinate of PD signal receiver；If n-th_tIndividual The coordinate of LED signal transmitter isN-th_rThe coordinate of individual PD signal receiver is

2.2) according to geometrical relationship, each LED signal transmitter angle of emergence φ to all PD signal receivers is calculated, n-th_tIndividual LED signal transmitter is to n-th_rThe angle of emergence of individual PD signal receiver is:

$\begin{array}{c}{\mathrm{\φ}}_{n_t{n}_r}=\arccos \left(\frac{z_{n_t}-z_{n_r}}{\sqrt{{(x_{n_t}-x_{n_r})}^2+{(y_{n_t}-y_{n_r})}^2+{(z_{n_t}-z_{n_r})}^2}}\right)\\ n_t=1,2,\mathrm{...},N_T,n_r=1,2,\mathrm{...},N_R\end{array}$

2.3) n-th_tIndividual LED signal transmitter is respectively as follows: to angle of emergence φ of all PD signal receivers

${\mathrm{\φ}}_{n_{t}1},{\mathrm{\φ}}_{n_{t}2},...,{\mathrm{\φ}}_{n_t{N}_R}$

Take minima therein, be n-th_tThe minimum half-power angle of individual LED signal transmitter

Wherein, n_t=1,2 ..., N_T。