CN205670775U - A kind of adaptive visible ray OFDM baseband communication system - Google Patents
A kind of adaptive visible ray OFDM baseband communication system Download PDFInfo
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Abstract
A kind of adaptive visible ray OFDM baseband transmission system, including the serioparallel exchange module sequentially connected and modulation mapping block, inserts pilot tone zero-adding module, IFFT module, inserts cyclic prefix module, digital-to-analogue conversion and LED drive module, opto-electronic receiver and A/D modular converter, high-pass filtering and main amplifying circuit module, removes cyclic prefix module, FFT and removal pilot module, demodulation mapping block and parallel serial conversion module and self-adaptive control module.Serioparallel exchange constitutes modulated terminal with modulation mapping block, insertion pilot tone zero-adding module, IFFT module, insertion cyclic prefix module and this digital-to-analogue conversion with LED drive module.Opto-electronic receiver constitutes receiving terminal with A/D modular converter, high-pass filtering and main amplifying circuit module, removal cyclic prefix module, FFT with removal pilot module, demodulation mapping block and parallel serial conversion module.Being visible light channel between modulated terminal and receiving terminal, self-adaptive control module is all electrically connected with modulated terminal and receiving terminal and is used for channel to be estimated with self-adaptive processing.
Description
Technical field
This utility model relates to a kind of visible ray OFDM base band signal transmission transmitter, particularly to one is adaptive can
See light OFDM baseband transmitter.
Background technology
OFDM (OFDM) is a kind of by the wide variety of communication modulating technology of Technology of New Generation Mobile Communications.
OFDM belongs to multi-carrier modulation technology, breaks a channel into some orthogonal sub-channels, is converted into by high-speed data signal parallel low
Speed sub data flow, is loaded on orthogonal subcarrier and carries out multi sub-channel transmission.Owing to each subcarrier allows on frequency spectrum
Overlapping and can not interfere with each other, so the availability of frequency spectrum of OFDM is the highest when demodulation.And be equipped with OFDM technology as core
Indoor white light LEDs communication system become the focus of Recent study, because visible light communication system takes into account illumination with the most logical
The dual-use function of letter, and room light communication has information privacy function.In OFDM visible light communication system, every sub-channels
Above use quadrature amplitude modulation (QAM) to improve spectrum efficiency more.The most common modulation system has: QPSK, 16QAM and
64QAM tri-kinds, and can transmitted bit number be 2,4 and 6 bits respectively in subchannel.General ofdm system uses fixing
Modulation system, according to fixing QPSK modulation system, the transfer rate of system is minimum, and a subcarrier can only transmit 2 ratios
Special data；If the fixing modulation system using 16QAM, system transfers efficiency and error rate level are placed in the middle；According to fixing 64QAM
Modulation system be capable of the maximization of transfer rate, but its bit error rate is the biggest.
In order to improve the transmission performance of system, it is necessary to introduce the adaptive modulation technology of modulation system, i.e. estimated by channel
Meter obtains the concrete condition of each channel, the modulation methods that when then determining transmission next time according to channel situation, this channel uses
Formula, channel situation the most then uses the modulation system of high-order, and channel situation is poor, uses the modulation system of low order.Introduce adaptive
Answer technology, can fully improve the efficiency of transmission of system.
Utility model content
For solving the low problem of efficiency of transmission of fixed modulation mode ofdm system, improve modulation system flexible of system
Property and environmental suitability, this utility model provides a kind of modulation system adaptive visible ray OFDM baseband transmission system.This can
See that light OFDM baseband communication system includes serioparallel exchange module and modulation mapping block, the insertion pilot tone of order electric connection successively
And zero-adding module, IFFT module, insertion cyclic prefix module, digital-to-analogue conversion and LED drive module, opto-electronic receiver and A/D conversion
Module, high-pass filtering and main amplifying circuit module, removal cyclic prefix module, FFT and removal pilot module, demodulation mapping block
And parallel serial conversion module and self-adaptive control module.This serioparallel exchange and modulation mapping block, this insertion pilot tone zero-adding mould
Block, this IFFT module, this insertion cyclic prefix module and this digital-to-analogue conversion constitute modulated terminal with LED drive module.This photoelectricity connects
Receive and A/D modular converter, this high-pass filtering and main amplifying circuit module, this removal cyclic prefix module, this FFT and removal pilot tone
Module, this demodulation mapping block and this parallel serial conversion module constitute receiving terminal.It it is visible ray between this modulated terminal and this receiving terminal
Channel, this self-adaptive control module is all electrically connected with this modulated terminal and this receiving terminal and is used for carrying out channel to be estimated to carry out certainly
Adaptation processes.
The modulation of this modulated terminal produces OFDM digital baseband signal, and this digital baseband signal obtains simulation letter through digital-to-analogue conversion
Number, LED drive module drives white light LEDs to complete the transmitting of baseband signal, and opto-electronic receiver module carries out photodetection and reception should
Optical signal, this optical signal recycles the output of A/D modular converter after high-pass filtering and main amplifying circuit module are filtered amplifying
OFDM baseband digital signal, carries out signal demodulation output, this self adaptation simultaneously in each module in this digital signal input FPGA
Control module carries out self-adaptive processing.
This self-adaptive control module carries out the channel average signal-to-noise ratio that self-adaptive processing includes obtaining according to channel estimation, instead
Feeding this modulated terminal, this channel average signal-to-noise ratio is made comparisons, under determining by modulated terminal with the signal-noise ratio threshold value of each modulation system
The modulation system that secondary transmission is taked is QPSK, 16QAM or 64QAM.
Accompanying drawing explanation
In order to be illustrated more clearly that this utility model embodiment or technical scheme of the prior art, below will be to embodiment
Or the required accompanying drawing used is briefly described in description of the prior art, it should be apparent that, the accompanying drawing in describing below is only
It is embodiments more of the present utility model, for those of ordinary skill in the art, before not paying creative work
Put, it is also possible to obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the schematic diagram of self adaptation visible ray ofdm system.
Fig. 2 is serioparallel exchange and modulation mapping block hardware elementary diagram.
Fig. 3 is to insert pilot tone, zero-adding and IFFT hardware elementary diagram.
Fig. 4 is to insert cyclic prefix module hardware elementary diagram.
Fig. 5 is D/A change-over circuit figure.
Fig. 6 is LED drive circuit figure.
Fig. 7 is opto-electronic receiver circuit diagram.
Fig. 8 is high-pass filtering circuit figure.
Fig. 9 is main amplifying circuit figure.
Figure 10 is self-adaptive control module hardware elementary diagram.
Specific embodiment
Below in conjunction with the accompanying drawing in this utility model embodiment, the technical scheme in this utility model embodiment is carried out
Clearly and completely describe, it is clear that described embodiment is only a part of embodiment of this utility model rather than whole
Embodiment.Based on the embodiment in this utility model, those of ordinary skill in the art are not under making creative work premise
The every other embodiment obtained, broadly falls into the scope of this utility model protection.
This utility model solves adaptive method: inserts 4 known pilot tones in the OFDM sequence of modulated terminal, is
In order to carry out channel estimation at receiving terminal.The result that channel is estimated is the information obtaining channel, finally calculates the average of channel and misses
Code check, channel average signal-to-noise ratioComputing formula be:
Wherein siAnd riIt is i-th pilot signal and the i-th pilot signal of reception of transmission respectively.
Make comparisons with the threshold value of each modulation system, to determine the modulation system of transmission next time.Rule is as follows:
(i) whenDo not transmit data；
(ii) whenUse QPSK modulation system；
(iii) whenUse 16QAM modulation system；
(iv) whenUse 64QAM modulation system.
Wherein SNRQPSK、SNR16QAMAnd SNR64QAMIt is to be not more than 10 in target error rate-3On the premise of, according to each modulation
The ber curve of mode determines.As long as being capable of the self adaptation of modulation system, the data transmission speed of system just can be promoted
Rate, this is the novel optimization aim to be realized of this experiment.
Work process and the hardware circuit design thereof of visible ray OFDM baseband communication system of the present utility model are as follows: select
The fpga chip of the EP2C5T144C8 model of altera corp is hard in using Verilog HDL hardware program language to realize chip
Building of part circuit.The sub-carrier number of this visible ray OFDM baseband communication system is 64.FPGA achieves OFDM system in modulated terminal
The modulation of system, finally gives OFDM digital baseband signal, then is obtained through chip DAC0832 digital-to-analogue conversion by digital baseband signal
Analogue signal, drives the VISIBLE LIGHT EMISSION module of white light LEDs, completes the transmitting of baseband signal.At receiving terminal, use model is
The PIN photodiode of BPW34 and peripheral circuit carry out photodetection reception, after filtering, amplify after, utilize analog digital conversion
Chip ADC0809 output OFDM baseband digital signal.Each module in digital signal input FPGA carries out signal demodulation output,
Carrying out self-adaptive processing simultaneously, i.e. estimate the channel SNRs obtained according to channel, feed back to transmitting terminal, transmitting terminal is by this channel
Signal to noise ratio is made comparisons with the signal-noise ratio threshold value of each modulation system, determines that the modulation system that next time, transmission was taked is QPSK, 16QAM
Or 64QAM.The overall schematic diagram of system is presented in Fig. 1, and Adaptive OFDM system each key modules is described in detail below
Particular hardware realizes.
(1) serioparallel exchange (S/P conversion) and modulation mapping block
Refer to Fig. 2, for serioparallel exchange and modulation mapping block hardware elementary diagram.Wherein serioparallel exchange maps mould with modulation
In block, the implication of each label is as follows, the serial data that (1) inputs；(2) depositor of b × 48, effect is by serial number
According to storing into 48 groups of b byte datas；(3) the 1st groups of input data；(4) reference value of comparator；(5) comparator；(6) outfan
Enabling signal, comparator output is effective time equal；(7) mapping value outfan.
This serioparallel exchange realizes in FPGA with modulation mapping block.Different modulating mode: QPSK, 16QAM and 64QAM divide
Do not require that the bit number that each subcarrier transmits is b (b ∈ { 2,4,6}).So, serioparallel exchange module can be by a bit wide
Realize for the depositor that b, the degree of depth are 48.Binary input number evidence constantly fills the depositor of these b × 48, during until filling up
48 circuit-switched data can realize parallel output.
48 channel parallel datas need to be modulated mapping, and modulate mapping block mainly by comparator and data selector structure
Become.The high b/2 position of the b Bit data on each road is set to I road (in-phase component), and low b/2 position is set to Q road (quadrature component).Assume
The I on the i-th tunnel, Q component respectively with 2 presetbIndividual constellation point homophase, quadrature component are simultaneously entered comparator, if with certain
Comparative result when individual constellation point compares is equal, then comparator output high level marking signal at this.This marking signal is as number
According to the address signal of selector, data selector exports the constellation point value (two-way on I road corresponding to the i-th tunnel, Q road accordingly
It is all 8 Bit datas).It is to say, b Bit data is finally mapped to two-way 8 Bit data.
(2) pilot tone zero-adding module are inserted
Refer to Fig. 3, for inserting pilot tone, zero-adding and IFFT hardware elementary diagram.Wherein insert pilot tone zero-adding module each
The implication of label is as follows: the mapping value that (1) is input into by mapping block；(2) 4 pilot signals；(3) zero-signal；(4)FIFO
FIFO bin, can be by mapping value successively input data selector；(5) data selector.
This inserts pilot tone and zero-adding module realizes in FPGA.The function of this module is to insert in 48 data mapped
Enter 4 pilot signals, and insert zero-signal in other 12 positions, constitute 64 parallel datas.This module is mainly deposited by FIFO
Reservoir and data selector realize.FIFO memory follows the principle of " FIFO ", and the data first inputted are the most defeated at outfan
Going out, the data of rear input " are queued up " and are sequentially output, and data are cached and do not lose.
One input of data selector connects the outfan of FIFO, and other inputs of data selector connect 4
Pilot signal depositor and zero-signal depositor.
Assume for I road, by 48 data under the instruction of the address signal of 0～64 serial input in FIFO.Local
When location arrives zero-signal or pilot frequency locations, data selector is switched to export zero-signal or pilot signal；When address arrives
During 48 Data Positions, data selector exports 48 data according to priority.All 64 output results obtained are stored into
In the depositor of 8 × 64.The operational circumstances on Q road is as I road.
(3) IFFT module
Refer to Fig. 3, for inserting pilot tone, zero-adding and IFFT hardware elementary diagram.The wherein implication of each label of IFFT module
As follows: 64 inputs of (6) IFFT module；(7)IFFT；(8) 64 outfans of IFFT module.
This IFFT module realizes in FPGA.The realization of IFFT is automatically generated by IP kernel.The method generated is to open at FPGA
Feeling like jelly and open FFT MegaCore in part Quartus II and arrange guide interface and be configured parameter, arranging IFFT point number is 64.
The I road of a upper module and two, Q road output register are directly connected to real part input and the imaginary part input of IFFT module, enter
Row IFFT converts, and 64 complex result of output are also classified into real part and are stored by the depositor of respective 8 × 64 respectively with imaginary part.
(4) cyclic prefix module (inserting CP) is inserted
Refer to Fig. 4, for inserting cyclic prefix module hardware elementary diagram.Wherein insert each label in cyclic prefix module
Implication respectively as follows, (1)～(3) is first three storage byte of the dual port RAM of 8 × 64 respectively；(4) the 49th word of RAM
Joint, Cyclic Prefix is to export from here on；(5) from the data of IFFT；(6) output data.
This inserts cyclic prefix module and realizes in FPGA.The function of this module is: rear 16 exported the 64 of IFFT
Number (as Cyclic Prefix) copies to before symbol, constitutes the OFDM symbol of 80 data.This function is by two panels 8 × 64 twoport
RAM carries out ping-pong operation realization.64 parallel datas are sequentially inputted in the RAM of first 8 × 64, after write, under
64 parallel data switchings of secondary transmission are input in the RAM of second 8 × 64, and now first RAM write enters state is the free time,
Can be carried out the operation read.The most back and forth switch, by write and the reading separate operation of RAM, both realized data the most not
Disconnected write, the most conveniently carries out self-defined reading, and this is ping-pong operation.Being read when, first behind address
The numerical value that 16 bytes (address is 48～64) start reading out in RAM, then be 0～63 to sequentially read from address, i.e. may make up bag
Contain the OFDM symbol of 80 data of Cyclic Prefix (a length of 16).
(5) D/A converter module (D/A) and LED drive module
See also Fig. 5 and Fig. 6, respectively D/A change-over circuit figure and LED drive circuit figure.Wherein D/A change-over circuit
In the implication of each label respectively as follows: (1) fpga chip, output contains the OFDM digit symbol of Cyclic Prefix；(2)DAC0832
Digital to analog converter, uses through type working method；(3) power supply 5V；(4) LM358 operational amplifier；(5) ground connection；～(8) (6)
10k resistance；(9) LM358 operational amplifier；(10) output analogue signal.In LED drive circuit, the implication of each label is the most such as
Under: the analogue signal that (1) changes from D/A；(2) 10uf electric capacity；(3) power supply 12V；(4) 1.2k resistance；(5) 330 Ω resistance；
(6) 820 Ω resistance；(7) 2SC1815 transistor；(8) LED bulb；(9) 120 Ω resistance；(10) 10uf electric capacity；(11) ground connection.
OFDM symbol is carried out digital-to-analogue conversion by D/A converter module and LED drive module, and analogue signal is loaded into LED
On, launch.Wherein DAC0832 chip has been used in digital-to-analogue conversion, uses the mode of operation of through type, is turned by digital quantity in real time
Turn to analog quantity, be loaded into the DC bias circuit being made up of audion.The LED of 5 1W, lamp bright is connected on this pcb board
Spend and determined by the voltage swing of analog quantity.
(6) opto-electronic receiver and A/D modular converter
See also Fig. 7 and Fig. 8, respectively opto-electronic receiver circuit diagram and high-pass filtering circuit figure.Wherein opto-electronic receiver
In circuit, the implication of each label is as follows: (1)～(2) 1k resistance；(3) BPW34 photodiode；(4) ground connection；(5)
LM4562 operational amplifier；(6) 10uf electric capacity；(7) 10k resistance；(8) output voltage values.Each label in high-pass filtering circuit
Implication respectively as follows；(1) output voltage values of opto-electronic receiver module；(2) 100pf electric capacity；(3) 20pf electric capacity；(4)100pf
Electric capacity；(5) 10k resistance；(6) LM4562 operational amplifier；～(8) 10k resistance (7)；(9) ground connection；(10) filtering output.
Opto-electronic receiver module use BPW34 photodiode, this model diode have dark current little, response the most excellent
Point.This opto-electronic receiver module realizes amplifying across resistance, and the response current signal of photodiode is converted into voltage signal output.Electricity
Pressure signal circuit the most after filtering and main amplifying circuit realize signal denoising sound and amplification.A/D modular converter uses
ADC0809 chip, under the effect of external clock, realizes analog voltage amount at high speed and is converted to 8 bit digital quantity, be input to FPGA
In be demodulated.
(7) high-pass filtering and main amplifying circuit module
Refer to Fig. 9, for main amplifying circuit figure.Wherein the implication of each label of main amplifying circuit figure is as follows: (1) connects
Ground；(2) output of high-pass filtering, the input of amplifying circuit；～(4) 1k resistance (3)；(5) 20k resistance；(6) LM4562 computing is put
Big device；～(8) 1k resistance (7)；(9) 20k resistance；(10) LM4562 operational amplifier；(11) output is amplified.
High-pass filtering circuit can filter from the background noise such as electric filament lamp and sunlight, restores the OFDM mould of transmitting terminal
Intending signal, this device uses unlimited gain multiple feedback high-pass filtering circuit, and cut-off frequency is set as about 1MHZ.But reduction
Signal out is smaller, needs follow-up main amplifying circuit to realize signal and amplifies.This device uses two-stage anti-phase scaling
Circuit, it is achieved the voltage amplification effect of 400 times.
(8) cyclic prefix module (removing CP), FFT and removal pilot module, demodulation mapping block and parallel-serial conversion are removed
Module (P/S conversion)
These modules are all to realize in FPGA, and the circuit theory of lift-launch is identical with each respective modules of modulated terminal, only
Be realize process be contrary, so the most briefly introducing.
Remove cyclic prefix module, it is simply that by the RAM of rear 64 data write a piece of 8 × 64 of 80 data, it is achieved
The function of front 16 data (Cyclic Prefix) of removal.
FFT is with removal pilot module, and FFT uses IP kernel to build FFT and processes circuit, exports 64 parallel demodulation signals and deposits
Store up in the depositor that the degree of depth is 64, these 64 data contain 48 useful signals, 4 pilot signals and 12 zero letters
Number.Under the effect reading clock and reading address, specifically read the useful signal of 48 specific location, it is achieved that remove and lead
Frequency and the effect of zero-signal.
Demodulation mapping block achieves the inverse mapping of constellation point, and 48 data i.e. obtained according to FFT are at constellation figure
On homophase and quadrature component information, determine the value of original 48 b Bit data respectively.Realize the hardware foundation of this function still
It is comparator, will the data on these 48 pairs of I/Q roads make comparisons with the mapping value of previously-known constellation point, if equal, comparator
Then output high level marking signal.This marking signal enables signal, the most just as the output of the depositor storing former b Bit data
To say, when comparator go out comparative result be equal time, depositor export immediately correspondence mapping before the former data of b bit.
These modules of receiving terminal are similar due to the several module principles with modulated terminal, so not enclosing hardware elementary diagram.
(9) self-adaptive control module
Refer to Figure 10, for self-adaptive control module circuit theory diagrams.Wherein each mark in self-adaptive control module circuit
Number implication respectively as follows: (1) siAnd riIt is i-th pilot signal and the i-th pilot signal of reception of transmission respectively；(2) pass
Defeated pilot tone input；(3) squarer；(4) move to right 2 and realize division；(5) comparison of threshold value；(6) modulation system coding is defeated
Go out.
Channel estimation is the basis of self-adaptive control module, and self-adaptive control module is core of the present utility model.
The particular hardware circuit of this module is set up in FPGA.The process that channel is estimated is as follows: at the FFT of demodulating end
In output result, 4 pilot signals being read out, input multiplier carries out respective square operation the most respectively, obtains | si
|2；4 pilot signals received are separately input in subtractor carry out subtraction with former pilot signal, then input multiplier
Carry out square operation, obtain | ri-si|2。|si|2With | ri-si|2Computing of averaging used adder.In order to realize divided by 4
Effect, do not use divider, but data (8 two-stage system numbers) carried out moving to right 2 and realizes the computing that data are divided by 4, extremely
This completes the computing averaged, and obtainsWithFinally result is inputted divider and can obtain channel estimation value
Successively with SNRQPSK、SNR16QAMAnd SNR64QAMCompare, it is also desirable to used comparator.WhenIt is more than
During a certain threshold value, the flag bit set at this thresholding, thus can knowComparative result, next time transmission signal time
Modulation system this is determined.
This comparative result needs to be fed back to serioparallel exchange module.This is to pass on modulation strategy by two bit registers
Information.When two bit register numerical value are 00, represent and do not transmit data next time；When two bit register numerical value are 01, then under
Secondary employing QPSK；When two bit register numerical value are 10, then use 16QAM next time；When two bit register numerical value are 11, then under
Secondary employing 16QAM.After serioparallel exchange module obtains this feedback information, i.e. bit value b of each subchannel of adjustable, b ∈ 2,
4,6}；Modulation mapping block is also required to obtain this feedback information, thus is modulated the Parameter Modulation mapped, i.e. on planisphere
The adjustment of mapping ruler.Here it is the hardware circuit of the Adaptive OFDM system realized with this utility model.
Above disclosed only this utility model preferred embodiment, can not limit this utility model with this certainly
Interest field, the equivalent variations therefore made according to this utility model claim, still belong to the scope that this utility model is contained.
Claims (9)
1. an adaptive visible ray OFDM baseband communication system, it is characterised in that this visible ray OFDM baseband communication system
Including the serioparallel exchange module that order is electrically connected with successively and modulation mapping block, insert pilot tone zero-adding module, IFFT module,
Insert cyclic prefix module, digital-to-analogue conversion and LED drive module, opto-electronic receiver and A/D modular converter, high-pass filtering and main amplification
Circuit module, remove cyclic prefix module, FFT and removal pilot module, demodulation mapping block and parallel serial conversion module and from
Suitable solution module, this serioparallel exchange and modulation mapping block, this insertion pilot tone zero-adding module, this IFFT module, this insertion
Cyclic prefix module and this digital-to-analogue conversion constitute modulated terminal, this opto-electronic receiver and A/D modular converter, this height with LED drive module
Pass filter and main amplifying circuit module, this removal cyclic prefix module, this FFT and removal pilot module, this demodulation mapping block
And this parallel serial conversion module constitutes receiving terminal, it is visible light channel between this modulated terminal and this receiving terminal, this self-adaptive controlled molding
Block is all electrically connected with this modulated terminal and this receiving terminal and is used for carrying out channel to be estimated to carry out self-adaptive processing.
Adaptive visible ray OFDM baseband communication system the most according to claim 1, it is characterised in that: this modulated terminal is adjusted
System produces OFDM digital baseband signal, and this digital baseband signal obtains analogue signal through digital-to-analogue conversion, and LED drive module drives
White light LEDs completes the transmitting of baseband signal, and opto-electronic receiver module carries out photodetection and receives this optical signal, and this optical signal is through height
Pass filter and main amplifying circuit module recycle A/D modular converter output OFDM baseband digital signal after being filtered amplifying, should
Carrying out signal demodulation output in each module in digital signal input FPGA, this self-adaptive control module is carried out at self adaptation simultaneously
Reason.
Adaptive visible ray OFDM baseband communication system the most according to claim 2, it is characterised in that: this is self-adaptive controlled
Molding block carries out the channel average signal-to-noise ratio that self-adaptive processing includes obtaining according to channel estimation, feeds back to this modulated terminal, modulation
This channel average signal-to-noise ratio is made comparisons by end with the signal-noise ratio threshold value of each modulation system, determines the modulation methods that next time, transmission was taked
Formula is QPSK, 16QAM or 64QAM.
Adaptive visible ray OFDM baseband communication system the most according to claim 3, it is characterised in that: channel is averagely believed
Make an uproar ratioComputing formula be:
Wherein siAnd riIt is i-th pilot signal and the i-th pilot signal of reception of transmission respectively；
Make comparisons with the threshold value of each modulation system, to determine the modulation system of transmission next time.
Adaptive visible ray OFDM baseband communication system the most according to claim 4, it is characterised in that:
(i) whenDo not transmit data；
(ii) whenUse QPSK modulation system；
(iii) whenUse 16QAM modulation system；
(iv) whenUse 64QAM modulation system；
Wherein SNRQPSK、SNR16QAMAnd SNR64QAMIt is to be not more than 10 in target error rate-3On the premise of, according to each modulation system
Ber curve determines.
Adaptive visible ray OFDM baseband communication system the most according to claim 1, it is characterised in that: this serioparallel exchange
Module be a bit wide be b, the degree of depth be the depositor of 48.
Adaptive visible ray OFDM baseband communication system the most according to claim 1, it is characterised in that: this modulation maps
Module includes comparator and data selector.
Adaptive visible ray OFDM baseband communication system the most according to claim 1, it is characterised in that: this insertion pilot tone
And zero-adding module includes FIFO memory and data selector.
Adaptive visible ray OFDM baseband communication system the most according to claim 1, it is characterised in that: high-pass filtering mould
Block uses unlimited gain multiple feedback high-pass filtering circuit, and cut-off frequency is set as 1MHZ.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107181526A (en) * | 2017-06-20 | 2017-09-19 | 东北大学 | A kind of visible light wireless communication physical layer optical frequency modulator |
| CN107343265A (en) * | 2017-08-16 | 2017-11-10 | 华南理工大学 | A kind of visible ray alignment system and method based on maximal possibility estimation |
| CN107395277A (en) * | 2017-08-04 | 2017-11-24 | 苏州大学 | A kind of visible light communication system based on ADO OFDM |
-
2016
- 2016-05-06 CN CN201620413363.2U patent/CN205670775U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107181526A (en) * | 2017-06-20 | 2017-09-19 | 东北大学 | A kind of visible light wireless communication physical layer optical frequency modulator |
| CN107181526B (en) * | 2017-06-20 | 2023-04-18 | 东北大学 | Visible light wireless communication physical layer optical frequency modulator |
| CN107395277A (en) * | 2017-08-04 | 2017-11-24 | 苏州大学 | A kind of visible light communication system based on ADO OFDM |
| CN107343265A (en) * | 2017-08-16 | 2017-11-10 | 华南理工大学 | A kind of visible ray alignment system and method based on maximal possibility estimation |
| CN107343265B (en) * | 2017-08-16 | 2023-07-18 | 华南理工大学 | Visible light positioning system and method based on maximum likelihood estimation |
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