CN205754338U - A kind of alignment system of visible light communication localization method based on CDMA modulation - Google Patents

Abstract

The utility model discloses the alignment system of a kind of visible light communication localization method based on CDMA modulation, including: launch subsystem, transmission subsystem and receiving subsystem；This utility model has the precision not only substantially increasing location, and system is simple and need not synchronized transmissions, substantially increases the performance of system.The advantage such as have broad application prospects.

Description

A kind of alignment system of visible light communication localization method based on CDMA modulation

Technical field

This utility model relates to visible light communication location technology, particularly to a kind of based on CDMA modulation The alignment system of visible light communication localization method.

Background technology

Global positioning system (Global Positioning System, GPS) is good outdoor application navigation System, has a wide range of applications in industries such as cell phone map service, auto navigation, boats and ships and aircrafts.At present GPS outdoor positioning technology is the most ripe, and is widely used in every field, and this largely swashs The R and D of indoor positioning technologies are encouraged.In recent years, indoor positioning technologies has attracted increasing pass Note, such as the product orientation detection in bulk storage plant, navigation Service (museum, the shopping within heavy construction Center, parking lot) etc..But under interior of building, densely populated city, bridge, inferior environment, Owing to the impact of multipath fading and the interference of other wireless devices make GPS signal in building cover Poor, there is bigger error for indoor positioning.

Since more than ten years recently, each science and technology giant and research institution have carried out in terms of indoor positioning technologies in a large number Research, emerged in large numbers a lot of new technology, as assistant GPS (A-GPS) based on mobile communications network, Pseudo satellite, pseudolite (Pseudolite), WLAN (WLAN), RFID, Zigbee, bluetooth, ultra broadband Radio (Ultra Wide Band, UWB), magnetic survey satellite, infrared location, light track and localization, Computer vision location, ultrasonic locating, these methods provide the positioning precision from several meters to tens centimetres. But, great majority system based on radio communication can be by electromagnetic interference influence, in the feelings that multiple users share Under condition, communication quality declines, and these all directly affects alignment quality.With above-mentioned traditional indoor positioning scheme Different, it is seen that light indoor positioning technologies be based on visible light communication (visible light communication, VLC) indoor positioning technologies, by controlling the light intensity of LED with eye recognition high frequency not, And then propagate the id information of location.VLC location technology has positioning accurate relative to tradition indoor positioning technologies Degree is high, add-on module is few, good confidentiality, take into account communication and illumination, and does not has electromagnetic radiation, not by electromagnetism The advantages such as interference, it has also become the study hotspot of research worker both at home and abroad.

Location algorithm based on VLC mainly have received signal strength (Received signal strength, RSS), The time of advent (Time of arrival, TOA) and poor (the Time difference of time of advent arrival,TDOA).Owing to RSS can measure phase by measuring signal attenuation degree in transmittance process Close distance, be not required to TOA or TDOA receiving terminal and transmitting terminal has clock cycle of stringent synchronization, control System is simple, has good application prospect.But, owing to alignment system existing multiple reference point, different The ID location information that information source is launched can produce intersymbol interference due to the existence of multipath effect, and then significantly Limit the precision of location.

Utility model content

Primary and foremost purpose of the present utility model is that the disadvantages mentioned above overcoming prior art, with not enough, proposes a kind of real Now visible light communication localization method based on CDMA modulation, the method expands in modulating by utilizing CDMA The orthogonality of frequency code, the alignment code that each LED sends is through specific PN code Direct-Spread, via certainly Adaptive filter can tell the ID code of each LED and corresponding intensity.

Another object of the present utility model is that the disadvantages mentioned above overcoming prior art, with not enough, proposes a kind of real The now alignment system of visible light communication localization method based on CDMA modulation, this system is by merging CDMA modulation technique, builds a high accuracy indoor visible light communication location that can realize Asynchronous Reception System.

Primary and foremost purpose of the present utility model is achieved through the following technical solutions: a kind of based on CDMA modulation Visible light communication localization method, comprises the following steps:

Id information corresponding to step 1, each LED lamp is by forming bandwidth after OOK baseband modulation For B₁Baseband modulation signal；

Step 2, described baseband modulation signal carry out spread processing through PN code produced by PN code generator After, formed and carry a width of B₂Spread-spectrum signal, wherein, B₂Much larger than B₁；

Step 3, described spread-spectrum signal drive LED lamp to send visible light signal through LED drive circuit；

Step 4, be positioned at ground by 3 identical photodiodes equilateral triangle with the length of side as 0.01m After the photoelectricity testing part of shape arrangement receives visible light signal, then obtain through corresponding signal processing technology Obtain id information；

Step 5, according to described id information and combine RSS triangle polyester fibre algorithm, finally draw location Position coordinates.

Described step 4 comprises the following steps:

Step 41, described visible light signal form the signal of telecommunication after photoelectricity testing part；

Step 42, the described signal of telecommunication form despreading after EA amplifying circuit and sef-adapting filter process Front signal；

Step 43, CDMA despreading module catches what LED lamp was launched by built-in synchronous circuit The accurate phase of PN code, thus produces the signal before the PN code consistent with transmitting terminal phase place and described despreading Carry out despreading process, restore id information.

RSS triangle polyester fibre algorithm in described step 5 calculates:

Step 51, each LED carry the id information after CDMA encodes in the interior space Middle propagation, the path of spatial transmission is seen as LOS link, therefore, from LED to receiving terminal direct projection sighting distance light The mathematic(al) representation of channel DC current gain H (0) is:

$H\left(0\right)=\frac{1}{d^2}\·A_{LED}\left(\mathrm{\θ}\right)\·A_{PD}\left(\mathrm{\ψ}\right),---\left(1\right)$

Wherein, θ is the angle of departure of LED lamp, and ψ is the acceptance angle of photodiode, photodiode and The distance of corresponding light fixture is d, A_LED(θ) it is the LED gain when θ, A_PD(ψ) it is that PD is when ψ Gain；

Signal b is obtained through oversampling judgement_i(t), this signal may be considered the primary signal that LED sends, With through sef-adapting filter y_iT the signal of () is made comparisons, i.e. can get signal decay H (0) in space, Decay H (0) includes the optical attenuation of space channel, additive white Gaussian noise；According to formula 1, i.e. draw light Electric diode and distance d of corresponding LED lamp；

$d=\sqrt{\frac{A_{LED}\left(\mathrm{\θ}\right)\·A_{PD}\left(\mathrm{\ψ}\right)\·P_{b_i\left(t\right)}}{P_{y_i\left(t\right)}}},---\left(2\right)$

Wherein, P_yi(t)It is the power of the signal extracting respective channels after matched filtering device,It is The signal restored after judgement；Wherein H is the vertical dimension of LED and PD； When PD horizontal positioned, ψ=θ；

Project to the plane at PD place, the horizontal range of PD Yu LEDThus may be used Draw photodiode and three LED in the positioning unit formed respectively with every 4 LED lamp The relational expression of tool:

$\left\{\begin{array}{c}{(x-x_1)}^2+{(y-y_1)}^2={d_{xy1}}^2\\ {(x-x_2)}^2+{(y-y_2)}^2={d_{xy2}}^2\\ {(x-x_3)}^2+{(y-y_3)}^2={d_{xy3}}^3\end{array}\right.,---\left(3\right)$

Wherein, subscript 1,2 and 3 represents LED1, LED2 and LED3 respectively；[x₁、x₂、x₃] and [y₁、 y₂、y₃] it is respectively abscissa corresponding to LED1, LED2, LED3 and vertical coordinate；[d_xy1、d_xy2、d_xy3] It is respectively PD and LED1, horizontal range between LED2, LED3；By solving above-mentioned equation group, I.e. can determine that PD place exact position (x, y)；

Step 52, after method obtains the coordinate of 3 photodiodes respectively as described in step 51, ask corresponding Barycenter oftriangle, i.e. obtains accurate position coordinates.

Position location coordinate in described step 5 is the region being determined location by id information, passes through RSS Triangle polyester fibre algorithm determines photodiode and the distance of three different LED lamp in region, location, and then Realize accurate location.

Another object of the present utility model is achieved through the following technical solutions: a kind of realization is adjusted based on CDMA The alignment system of the visible light communication localization method of system, including: launch subsystem, transmission subsystem and reception Subsystem.It is characterized in that: original id information, after OOK baseband-modem module, forms base band Modulated signal；Described baseband modulation signal forms spread-spectrum signal after CDMA spread spectrum module；Described expansion Frequently signal drives LED lamp to launch visible ray ID signal through LED drive circuit；Described visible ray ID Signal arrives photoelectricity testing part through free space；Visible ray ID signal is turned by described photoelectricity testing part It is changed to the signal of telecommunication；The described signal of telecommunication sequentially passes through amplifying circuit, auto-adaptive filter circuit and CDMA again and solves Expand the decay of signal when module finally obtains ID signal and spatial transmission；According to described ID signal, permissible The preliminary region judging position, and according to the decay size of signal, it is achieved accurate location positioning.

Described transmitting subsystem includes that OOK baseband-modem module, CDMA spread spectrum module, LED drive Circuit and LED lamp.

Described transmission subsystem is free space.

Described receiving subsystem has: photoelectricity testing part, amplifying circuit, auto-adaptive filter circuit and CDMA de-spreads module.

Owing to visible light communication alignment system has multiple LED lamp, and between different LED lamp due to Intersymbol interference thus leverage the degree of accuracy of location.To this end, propose a kind of based on CDMA modulation Visible light communication location algorithm, utilize that LED lamp launched by CDMA modulation technique with ID label Optical signal encode, mobile terminal receives the mixed signal of the optical signal from each LED light source, Owing to CDMA spread spectrum coding has orthogonality, the information of each LED light source and corresponding light letter can be recovered Number decay, according to id information and its decay size, utilize triangle polyester fibre algorithm can realize mobile terminal Be accurately positioned.The precision of location is not only substantially increased compared with traditional visible light communication location technology, and And system is simple and need not synchronized transmissions, substantially increases the performance of system.Have broad application prospects.

Compared with prior art, this utility model has the following advantages and beneficial effect:

1, CDMA modulation technique is applied in VLC system by this utility model innovatively, is not increasing On the premise of adding bandwidth of a device, improve speed and the quality of radio communication exponentially.

2, this utility model is for the multipath effect brought owing to there is multiple reference point in alignment system Problem, innovatively practical light orthogonal code, it is possible to achieve at the Signal separator that time-domain and frequency-domain is all overlapping, enter And achieve code division multiplexing, overcome the position error brought due to intersymbol interference.

3, this utility model is by using CDMA modulation technique and RSS triangulation location phase innovatively In conjunction with, compared with traditional alignment system, not only achieve high-precision location technology, and need not same Step is launched, and considerably increases the stability of VLC alignment system.

Accompanying drawing explanation

Fig. 1 is the schematic diagram that this utility model realizes visible light communication location.

Fig. 2 is that this utility model realizes visible light communication indoor locating system principle based on CDMA modulation Block diagram.

Fig. 3 is the theory diagram of this utility model Resistant DS Spread Spectrum System.

Fig. 4 is that this utility model realizes VLC alignment system theory diagram based on CDMA modulation.

Fig. 5 is the principle schematic that this utility model realizes triangle polyester fibre algorithm.

Fig. 6 is this utility model embodiment sef-adapting filter theory diagram.

Detailed description of the invention

Below in conjunction with embodiment and accompanying drawing, this utility model is described in further detail, but this practicality is new The embodiment of type is not limited to this.

Embodiment 1

As it is shown in figure 1, the system model of a kind of visible light communication location algorithm based on CDMA modulation. Demand according to indoor environment arranges m LED lamp, and wherein, m is positive integer, and m >=4； Using every 4 LED lamp as the position units of a location.On ground, by 3 identical photoelectricity two The pole pipe equilateral triangle composition photoelectricity testing part with the length of side as 0.01m.

As in figure 2 it is shown, original id information is after OOK baseband-modem module, form baseband modulation Signal；Described baseband modulation signal forms spread-spectrum signal after CDMA spread spectrum module；Described spread spectrum letter Number through LED drive circuit drive LED lamp launch visible ray ID signal；Described visible ray ID signal Photoelectricity testing part is arrived through free space；Visible ray ID signal is converted to by described photoelectricity testing part The signal of telecommunication；The described signal of telecommunication sequentially passes through amplifying circuit, auto-adaptive filter circuit and CDMA again and de-spreads mould The decay of signal when block finally obtains ID signal and spatial transmission；According to described ID signal, can be preliminary Judge the region of position, and according to the decay size of signal, it is achieved accurate location positioning.Described CDMA spread spectrum with despreading principle as it is shown on figure 3, the implementation case wherein uses DSSS skill Art.

As shown in Figure 4, in this utility model, it is achieved VLC alignment system based on CDMA modulation is former Reason block diagram.The id information that three LED lamp distribution inputs are different, at corresponding CDMA spread spectrum After reason, it is achieved that VLC triangle polyester fibre algorithm based on CDMA.Data1 includes each LED uniqueness The signal that ID signal and needs are propagated.The Data1 of each LED is by taking advantage of with specific spread spectrum code-phase.This The spread spectrum code used in case study on implementation is Walsh code.One a length of 2n, there is the Walsh of 2n element Code can pass through hadamard matrix (Hadamard matrix) and produce, such as formula

$H_n=\left[\begin{array}{cc}{H}_{n-1}& H_{n-1}\\ H_{n-1}& \stackrel{\‾}{H_{n-1}}\end{array}\right]---\left(4\right)$

Signal after DS-CDMA encodes, by LED drive circuit, controls the luminescence of LED Brightness, with in same traffic channel to PD, the mixed signal received is as shown in formula.

$r\left(t\right)={\mathrm{\Σ}}_{i=1}^{\mathrm{\∞}}{\mathrm{\Σ}}_{k=1}^K{A}_k{b}_k\left(i\right)S_k(t-{\mathrm{iT}}_b)+\mathrm{\δ}n\left(t\right)t\∈\[{\mathrm{iT}}_b,(i+1)T_b\]---\left(5\right)$

Wherein, A_kRepresent the signal intensity of kth LED, b_kI () is the signal sequence of kth LED transmission Row, T_bIt is spaced for information symbol, S_kT () is normalization characteristic waveform.Kth in i-th information symbol interval Individual sef-adapting filter is output as:

y_k(i)=A_kb_k(i)+∑A_jb_j(i)ρ_jk+n_k (6)

Wherein, ρ_jkIt is kth and the cross-correlation of jth user characteristics waveform, is defined as:

${\mathrm{\ρ}}_{jk}={\∫}_0^{T_b}{S}_k\left(t\right)S_j\left(t\right)dt---\left(7\right)$

Due to the complete orthogonality of Walsh code, i.e. ρ_jkThe information of=0, each LED is through corresponding After joining wave filter, when obtaining ID signal and the spatial transmission of correspondence, the decay of signal.According to ID signal, Can tentatively judge the region of position, and according to decay size H (0) of signal, be accurately positioned out position Put.

As it is shown in figure 5, be the principle schematic of RSS triangle polyester fibre algorithm.Id information determines the position of location Put region, i.e. positioning unit；Photodiode and each LED can be obtained according to the decay receiving optical signal Distance between light fixture, and then realize accurate location positioning.

General commercial white light LEDs is fluorescent material LED, due to the operating lag of fluorescent material thus cause device Part bandwidth typically only has several MHZ.When system data transfer rate is higher, the restriction of LED bandwidth increases Add, and then make to expand to the impact of a signal, on adjacent signals, i.e. produce intersymbol interference, thus cause Error rate of system is greatly promoted, so VLC message transmission rate receives and greatly limits, can pass through The equilibrium treatment of channel improves the bandwidth of system；Meanwhile, randomness and the randomness of channel and be In system, circuit noise, phase shift etc. also can largely effect on quality and the precision of location；Further, at multiple access In access system, owing to multipath fading causes the incomplete orthogonality of each user code thus produce multi-user Interference (i.e. multi-access inference), can be solved by post-equalization treatment technology.Therefore, this project is intended logical Cross use DSP signal processing technology and realize adaptive filter algorithm, and then realize equalization channel, offset Echo, enhanced line, suppresses the functions such as interchannel noise.As shown in Figure 6, intend using the filtering of FIR lateral type Device.By least mean-square error (Least Mean Square, LMS) algorithm adjust filter coefficient from And realize carrying out moment regulation filter parameter according to the change of signal.Thus solve bandwidth of a device and multiplex The problem to location precision such as family interference.

Above-described embodiment is only a kind of embodiment of the present utility model, but embodiment of the present utility model is also Being not restricted to the described embodiments, other are any is made without departing from spirit of the present utility model and principle are lower Change, modify, substitute, combine, simplify the substitute mode that all should be equivalence, be included in this practicality newly The protection domain of type it.

Claims (6)

1. the alignment system of a visible light communication localization method based on CDMA modulation, it is characterised in that Including: launch subsystem, transmission subsystem and receiving subsystem；Described transmitting subsystem has: OOK Baseband-modem module, CDMA spread spectrum module, LED drive circuit and LED lamp；Described reception subsystem System has: photoelectricity testing part, amplifying circuit, auto-adaptive filter circuit and CDMA de-spread module；Institute Stating transmission subsystem is free space；Described OOK baseband-modem module, CDMA spread spectrum module, LED Drive circuit and LED lamp are sequentially connected with；Described photoelectricity testing part, amplifying circuit, adaptive-filtering Circuit and CDMA despreading module are sequentially connected with；Original id information after OOK baseband-modem module, Form baseband modulation signal；Described baseband modulation signal forms spread-spectrum signal after CDMA spread spectrum module； Described spread-spectrum signal drives LED lamp to launch visible ray ID signal through LED drive circuit；Described can See that light ID signal arrives photoelectricity testing part through free space；Described photoelectricity testing part is by visible ray ID Signal is converted to the signal of telecommunication；The described signal of telecommunication sequentially pass through again amplifying circuit, auto-adaptive filter circuit and The decay of signal when CDMA despreading module finally obtains ID signal and spatial transmission；According to described ID Signal, can tentatively judge the region of position, and according to the decay size of signal, it is achieved accurate position Put location.

Alignment system the most according to claim 1, it is characterised in that described CDMA spread spectrum system For Resistant DS Spread Spectrum System；Described Resistant DS Spread Spectrum System includes: PN code generator and spread spectrum are adjusted Molding block；Described PN code generator is connected with band spectrum modulation module, described modulates information and band spectrum modulation Module is connected；Information becomes a width of B of band after modulates information₁Baseband modulation signal, described base band adjust PN code produced by signal processed and PN code generator carries out spread processing and forms a width of B of band₂Spread-spectrum signal, Wherein, B₂More than B₁。

Alignment system the most according to claim 1, it is characterised in that described LED lamp is according to room The demand of interior environment arranges m, and wherein, m is positive integer, and m >=4；With every 4 LED Have the position units as a location, realize triangle polyester fibre algorithm by three LED lamp therein, And combine the accurate location of attenuation factor realization through described transmission subsystem.

Alignment system the most according to claim 1, it is characterised in that described photoelectricity testing part by 3 identical photodiodes triangular arranged with the length of side as 0.01m, owing to the light of LED exists In natural environment, transmission can produce decay, by the decay of light intensity is carried out computing, can calculate photoelectricity two Pole pipe and the distance of LED.

Alignment system the most according to claim 1, it is characterised in that described CDMA de-spreads module Caught the accurate phase of the PN code that LED lamp is launched by built-in synchronous circuit, thus produce The PN code consistent with transmitting terminal phase place, as the local signal of despreading, to realize despreading.

Alignment system the most according to claim 1, it is characterised in that described auto-adaptive filter circuit Adjust filter coefficient by least-mean-square error algorithm thus realize carrying out the moment according to the change of signal and adjust Joint filter parameter.