CN204967862U - High -speed wireless pollution sources data transmission system based on OFDM technique - Google Patents
High -speed wireless pollution sources data transmission system based on OFDM technique Download PDFInfo
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Abstract
The utility model discloses a high -speed wireless pollution sources data transmission system based on OFDM technique, this data transmission system adopt the OFDM technical design to use FPGA hardware to build, this data transmission system includes data transmission unit and data receiving unit, and the data transmission unit sends data receiving unit with data signal through wireless channel, the data transmission unit be by RS coding module, the module that interweaves, constellation mapping module, IFFT operation module, insert circulation prefix module and RF emission module constitutes, data receiving unit is by RF receiving module, the prefix module of going to circulate, FFT operation module, constellation de -mapping module, separates interweave module and RS decoder module and constitute. The technical scheme of the utility model overcome the not enough problem of traditional low -speed data transmission ability, can communicate with radio communication net and wiFi, can realize remote, the wide big data transmission who covers, improved data transmission efficiency, guaranteed the stability and the reliability of transmission, can reliably monitor pollution sources in real time.
Description
Technical field
The utility model belongs to wireless communication technology field, particularly relates to a kind of high-speed radio pollutant sources data transmission system based on OFDM technology.
Background technology
Orthogonal frequency division multiplexi (OFDM) is the one of multi-carrier modulation.A wide band frequency channel is divided into some orthogonal sub-channels, high-speed data signal is converted to parallel low speed sub data flow, be modulated on every sub-channels and transmit.OFDM is a kind of Multicarrier Transmission Technology serial data of two-forty being realized parallel transmission by frequency division multiplexing.Within 2000, OFDM is applied to 802.11a, 802.16, LTE, in China, radio administration of the Ministry of Information Industry also have approved August 31 calendar year 2001 the test that China Netcom carries out OFDM fixed wireless access system CelerFlex, this system is own through open-minded at present, and has carried out necessary test and business demonstration.At present, people start the application of research and development OFDM in wireless mobile communications field of concentrating one's energy, and OFDM technology are combined with multiple multiple access technology.Because the Wireless Data Transmission in pollutant sources is adopt narrow band transmission technology mostly, due to smaller bandwidth, be difficult to the concurrent requirement adapting to the large data of Internet of Things, simultaneously narrow band transmission technology poor anti jamming capability.
Summary of the invention
The purpose of this utility model is to provide a kind of high-speed radio pollutant sources data transmission system based on OFDM technology, this data transmission system overcomes the problem of the deficiency of conventional low data transmission capabilities, can communicate with WiFi with wireless communication networks, remote, the wide large transfer of data covered can be realized, improve data transmission efficiency, ensure that stability and the reliability of transmission, reliably can monitor pollutant sources in real time.
For achieving the above object, the technical solution of the utility model is as follows: a kind of high-speed radio pollutant sources data transmission system based on OFDM technology, and described data transmission system adopts OFDM technology design, and use FPGA hardware to build; Comprise data transmission unit and data receipt unit; Data-signal is sent to data receipt unit by wireless channel by described data transmission unit;
Described data transmission unit comprises:
RS coding module; The IP kernel design that described RS coding module adopts QUARTUSII to carry, RS coding is a kind of channel coding method, for carrying out chnnel coding to baseband signal, carries out EDC error detection and correction to information code element, and the noise in elimination channel is to the interference of useful signal;
Interleaving block; Described interleaving block is for data interlacing, at time domain or the simultaneously information bit of Distributed Transmission on time domain, frequency domain, the burst error of channel is spread in time, will the bursty errors of digital data transmission be caused, carry out discrete and correct, improving the transmission characteristic of mobile communication;
Constellation mapping block; Described constellation mapping block carries out the modulation of M binary digits to original bit stream, by the constellation that the information MAP of different purposes is different, incoming bit stream signal is become parallel signal from serial signal through serioparallel exchange, be used for reducing character rate, in band-limited channel, transmit more data, improve data rate to bandwidth ratio;
IFFT calculation process module; The described IFFT of being calculation process module is the modulation of OFDM, for calculating the snap back Fourier transform of input;
Insert cyclic prefix module; Described insertion cyclic prefix module is the intersymbol interference caused for eliminating multipath, and OFMD symbol needs to insert Cyclic Prefix signal inside its protection interval, comes before copying to by a few bit data after OFDM symbol;
D/A module; Described D/A module is that digital signal is converted to analog signal, carries out air transmission;
RF transmitter module; Described RF transmitter module sends the analog signal after D/A module converts for data receipt unit;
Described data-signal is after RS coding module is encoded, send to interleaving block and carry out data interlacing, send into IFFT calculation process module after data interlacing and carry out IFFT conversion, data-signal enters insertion cyclic prefix module and carries out insertion Cyclic Prefix after IFFT conversion terminates, enter D/A module again and carry out parallel-serial conversion, send data-signal finally by RF transmitter module to data receipt unit;
Described data receipt unit comprises:
RF receiver module; Described RF receiver module is used for receiving at receiving terminal the data-signal that in from data transmission unit, RF transmitter module sends;
A/D module; Described A/D module is that analog signal is converted to digital signal, is convenient to carry out Signal transmissions in systems in which;
Go cyclic prefix module; Described cyclic prefix module of going inserts the reverse operating of cyclic prefix module in data transmission unit, by OFDM symbol by insertion cyclic prefix module copy to a few bit data above revert to after come;
FFT calculation process module; Described FFT calculation process module is fast rapid-result Fourier transform, time-domain signal is converted into frequency-region signal, it is the inverse transformation of IFFT in data transmission unit, FFT calculation process module is transplanted in hardware FPGA and goes, by in hardware FPGA chip, carry out FFT calculation process and obtain frequency energy value, effectively improving system signal processing speed;
Constellation demapping module; Described constellation demapping module is that the data-signal of data transmission unit is carried out de-mapping process, and incoming bit stream signal is become serial signal through parallel signal conversion;
De-interleaving block; Described de-interleaving block is that data-signal is carried out deinterleaving process, and the data-signal received is reverted to correct position;
With RS decoder module; Described RS decoder module carries out reduction decoding process to the data-signal of being encoded by RS;
Described data receipt unit is the data-signal analog signal of reception obtained after the sampling of A/D module converts, then data-signal is decomposed into single frame data signals one by one, and single frame data signals obtains initial data successively after past cyclic prefix module, FFT module, constellation demapping module, de-interleaving block and RS decoder module.
Preferentially, described wireless channel is wireless communication networks or WiFi.
Preferentially, between RS coding module and interleaving block, RSbuffer module is provided with; Described RSbuffer module is for accessing the data of RS coding module.
Preferentially, the bandwidth of described OFDM is 12.5MHz, and the modulation system of data is OFDM and 16DQPSK, and carrier number is 512, and the length of Frame is 1.953ms, comprises 640 symbols in subframe, wherein 128 Cyclic Prefix and 512 data.
Preferentially, the coded system of described RS coding module is (128,96)--the reduction form of (255,223).
Preferentially, described interleaving block adopts Block Interleaver, and it is 512 that interleaver is counted, interleaver primarily of reading, writing address sequencer, two-port RAM and read and write a few part composition of enable control; Wherein reading, writing address sequencer is mainly used to the read-write control signal producing two-port RAM, and determines when reading, writing address sequencer starts work.
In technique scheme, a kind of high-speed radio pollutant sources data transmission system based on OFDM technology of the present utility model is the high efficiency in order to improve pollutant sources data transmission system, OFDM technology is utilized to devise a kind of pollutant sources data radio transmission system, radio data channels is divided into several orthogonal sub-channels, convert high speed pollutant sources data-signal to parallel low speed sub data flow, be modulated on every sub-channels and transmit.Orthogonal signalling can by adopting filter or correlation technique to separate at receiving terminal, the mutual interference between subchannel can be reduced like this, thus improve high efficiency and the antijamming capability of wireless communication transmissions system, enhance the accuracy of blowdown enterprise supervision pollutant sources.Data transmission system comprises data transmission unit and data receipt unit, data transmission unit data-signal is after RS coding module is encoded, send to interleaving block and carry out data interlacing, send into IFFT calculation process module after data interlacing and carry out IFFT conversion, data-signal enters insertion cyclic prefix module and carries out insertion Cyclic Prefix after IFFT conversion terminates, enter D/A module again and carry out parallel-serial conversion, data-signal is sent to data receipt unit finally by RF transmitter module, data receipt unit is the data-signal analog signal of reception obtained after the sampling of A/D module converts, then data-signal is decomposed into single frame data signals one by one, single frame data signals is successively through past cyclic prefix module, FFT module, constellation demapping module, initial data is obtained after de-interleaving block and RS decoder module.The beneficial effects of the utility model are: the first, overcome the problem of the deficiency of conventional low data transmission capabilities; The second, can communicate with WiFi with wireless communication networks, remote, the wide large transfer of data covered can be realized; 3rd, improve data transmission efficiency, ensure that stability and the reliability of transmission, reliably can monitor pollutant sources in real time.
Accompanying drawing explanation
Fig. 1 is the structured flowchart of a kind of high-speed radio pollutant sources data transmission system based on OFDM technology of the utility model.
Embodiment
Below in conjunction with accompanying drawing, to the technical scheme in the utility model embodiment carry out clear, intactly set forth, described embodiment is only a part of embodiment of the present utility model, the embodiment of not all.Based on the embodiment in the utility model, those skilled in the art are not making the every other embodiment obtained under creative work prerequisite, all belong to the scope of the utility model protection.
As seen from Figure 1, a kind of high-speed radio pollutant sources data transmission system based on OFDM technology of the present embodiment adopts OFDM technology design, and use FPGA hardware to build, the bandwidth of OFDM is 12.5MHz, the modulation system of data is OFDM and 16DQPSK, and carrier number is 512, and the length of Frame is 1.953ms, 640 symbols are comprised, wherein 128 Cyclic Prefix and 512 data in subframe.This pollutant sources data transmission system comprises data transmission unit and data receipt unit, data-signal is sent to data receipt unit by wireless channel by data transmission unit, in the present embodiment, wireless channel comprises wireless communication networks and WiFi, in real work, also wireless channel and wired internet mixed networking can be used, thus realize remote, the wide large transfer of data covered.
In the present embodiment, data transmission unit is made up of RS coding module, interleaving block, constellation mapping block, IFFT calculation process module, insertion cyclic prefix module and RF transmitter module.
The IP kernel design that described RS coding module adopts QUARTUSII to carry, being a kind of channel coding method, for carrying out chnnel coding to baseband signal, carrying out EDC error detection and correction to information code element, and the noise in elimination channel is to the interference of useful signal.In the present embodiment, in order to ensure the reliability of communication system, noise in elimination channel is to the interference of useful signal, communication system needs to carry out chnnel coding to baseband signal, the basic thought of chnnel coding adds supervise code element in information code element, come information code element EDC error detection and correction according to the redundancy of these supervise code elements, RS coding is a kind of common channel coding method, RS coding adopts (255,223) reduction form (128,96) IP kernel, adopting QUARTUSII to carry in this design.The present embodiment is provided with RSbuffer module between RS coding module and interleaving block, and RSbuffer module is for accessing the data of RS coding module.
Interleaving block is for data interlacing, the bursty errors of digital data transmission will be caused, carry out discrete and correct, improve the transmission characteristic of mobile communication, interleaving block is in time domain or simultaneously in time domain, the information bit of Distributed Transmission on frequency domain, the burst error of channel is spread in time, thus make decoder they can be treated as random error process, in real work, interleaver shuffles code element in the scope of several block length or several constraint length, this scope determines channel burst wrong time, interweave and must cause time delay in systems in which, communication system usually defines the patient maximum delay of system, therefore also limit the interleave depth of the interleaver that can use.The interleaving block of the present embodiment adopts Block Interleaver, and it is 512 that interleaver is counted, interleaver primarily of reading, writing address sequencer, two-port RAM and read and write a few part composition of enable control; Wherein reading, writing address sequencer is mainly used to the read-write control signal producing two-port RAM, and determines when reading, writing address sequencer starts work.
Constellation mapping block carries out the modulation of M binary digits to original bit stream, by the constellation that the information MAP of different purposes is different, incoming bit stream signal is become parallel signal from serial signal through serioparallel exchange, be used for reducing character rate, in band-limited channel, transmit more data, improve data rate to bandwidth ratio; In the frequency band transmission system of reality, because the frequency resource of channel is limited, thus require to effectively utilize channel band, wish the utilance as far as possible improving channel band; In limited channel band, transmitting high speed data.For this reason, M binary digits modulation system must be adopted, by binary code at a high speed after M system (M>2) digital modulation, make the limit band requirement that modulated signal frequency band reaches given.But while consideration information transmission validity, must take into account the reliability of information transmission, namely will make the performance index that the error rate of this system reaches certain, this M binary digits modulation system different from employing is relevant.When M increases, its band efficiency increases, but for ensureing the error performance that system acquires a certain degree, just must to increase the average transmit power of signal as cost.So suitably select M value, the lowest bit rate required when can reduce transmission identical data, signal to noise ratio reduces again simultaneously, when carrying out the modulation of M binary digits, at a time, just may there is multiple possibility in the amplitude and the phase place that send signal.Left and right possibility is depicted in a rectangular coordinate system, just constitutes constellation.Thus, the Main Function of constellation mapping block, carries out the modulation of M binary digits to original bit stream exactly, be used for reducing character rate, in band-limited channel, transmit more data, improve data rate to bandwidth ratio, according to different rate requirement, the subcarrier of OFDM needs by BPSK, QPSK, 16QAM or 64QAM modulation system, after convolution coder and interleaver, the data flow every 1,2,4 of serial, 6 bits are divided into one group, be mapped to plural number with certain rule, form BPSK, QPSK, 16QAM, 64QAM symbol.Constellation mapping adopts 16DAPSK to map, it is that the former can adopt noncoherent demodulation that 16DAPSK maps the benefit mapped relative to 16QAM, because ofdm system affects very large by frequency deviation, so this modulation system can reduce the impact that frequency deviation causes for every sub-channels, the hydraulic performance decline that fading channel causes can be slackened simultaneously.
IFFT calculation process module is the modulation of OFDM, for calculating the snap back Fourier transform of input; The modulation and demodulation of OFDM can be realized by IFFT and FFT computing.In the present embodiment, FFT calculation process module is transplanted in hardware FPGA and goes, by hardware FPGA chip, carry out FFT calculation process and obtain frequency energy value, can effectively improve system signal processing speed.
Inserting cyclic prefix module is the intersymbol interference caused for eliminating multipath, and OFMD symbol needs to insert Cyclic Prefix signal inside its protection interval, comes before copying to by a few bit data after OFDM symbol.
D/A module is that digital signal is converted to analog signal, carries out air transmission.
RF transmitter module sends the analog signal after D/A module converts for data receipt unit.
Data receipt unit in the present embodiment by RF receiver module, go cyclic prefix module, FFT calculation process module, constellation demapping module, de-interleaving block and RS decoder module to form.RF receiver module is used for receiving at receiving terminal the data-signal that in from data transmission unit, RF transmitter module sends; A/D module is that analog signal is converted to digital signal, is convenient to carry out Signal transmissions in systems in which; Go cyclic prefix module to be in data transmission unit, insert the reverse operating of cyclic prefix module, by OFDM symbol by insertion cyclic prefix module copy to a few bit data above revert to after come; FFT calculation process module is fast rapid-result Fourier transform, time-domain signal is converted into frequency-region signal, it is the inverse transformation of IFFT in data transmission unit, FFT calculation process module is transplanted in hardware FPGA and goes, by in hardware FPGA chip, carry out FFT calculation process and obtain frequency energy value, effectively improving system signal processing speed; Constellation demapping module is that the data-signal of data transmission unit is carried out de-mapping process, and incoming bit stream signal is become serial signal through parallel signal conversion; De-interleaving block is that data-signal is carried out deinterleaving process, and the data-signal received is reverted to correct position; RS decoder module carries out reduction decoding process to the data-signal of being encoded by RS.
In the present embodiment, data-signal is after RS coding module is encoded, send to interleaving block and carry out data interlacing, send into IFFT calculation process module after data interlacing and carry out IFFT conversion, data-signal enters insertion cyclic prefix module and carries out insertion Cyclic Prefix after IFFT conversion terminates, enter D/A module again and carry out parallel-serial conversion, send data-signal finally by RF transmitter module to data receipt unit.Data receipt unit is the data-signal analog signal of reception obtained after the sampling of A/D module converts, then data-signal is decomposed into single frame data signals one by one, and single frame data signals obtains initial data successively after past cyclic prefix module, FFT module, constellation demapping module, de-interleaving block and RS decoder module.
In the present embodiment, interleaving block/de-interleaving block adopts 128*4 to realize, and it is that the Ram of 512*4bit, IFFT/FFT adopt 512 point quick Fourier inverse transformations that two modules call a size, the IP kernel using QUARTUSII to carry in this design.
The present embodiment inserts cyclic prefix module and goes in cyclic prefix module, and be inserted into the front end of data as Cyclic Prefix before adopting at latter 128 in OFDM data, it is the Ram of 512 that module calls a capacity.
The present embodiment is the high efficiency in order to improve pollutant sources data transmission system, OFDM technology is utilized to devise a kind of pollutant sources data radio transmission system, radio data channels is divided into several orthogonal sub-channels, convert high speed pollutant sources data-signal to parallel low speed sub data flow, be modulated on every sub-channels and transmit.Orthogonal signalling can by adopting filter or correlation technique to separate at receiving terminal, the mutual interference between subchannel can be reduced like this, thus improve high efficiency and the antijamming capability of wireless communication transmissions system, enhance the accuracy of blowdown enterprise supervision pollutant sources.
The above; it is only embodiment of the present utility model; not the utility model is imposed any restrictions; every above embodiment is done according to the utility model technical spirit any simple modification, change and equivalent method change, all still belong in the protection range of technical solutions of the utility model.
Claims (6)
1. based on a high-speed radio pollutant sources data transmission system for OFDM technology, it is characterized in that: this data transmission system adopts OFDM technology design, and use FPGA hardware to build; Comprise data transmission unit and data receipt unit; Data-signal is sent to data receipt unit by wireless channel by described data transmission unit;
Described data transmission unit comprises:
RS coding module; Described RS coding module is a kind of channel coding method, for carrying out chnnel coding to baseband signal, carries out EDC error detection and correction to information code element, and the noise in elimination channel is to the interference of useful signal;
Interleaving block; Described interleaving block is for data interlacing, at time domain or the simultaneously information bit of Distributed Transmission on time domain, frequency domain, the burst error of channel is spread in time, will the bursty errors of digital data transmission be caused, carry out discrete and correct, improving the transmission characteristic of mobile communication;
Constellation mapping block; Described constellation mapping block carries out the modulation of M binary digits to original bit stream, by the constellation that the information MAP of different purposes is different, incoming bit stream signal is become parallel signal from serial signal through serioparallel exchange, be used for reducing character rate, in band-limited channel, transmit more data, improve data rate to bandwidth ratio;
IFFT calculation process module; The described IFFT of being calculation process module is the modulation of OFDM, for calculating the snap back Fourier transform of input;
Insert cyclic prefix module; Described insertion cyclic prefix module is the intersymbol interference caused for eliminating multipath, and OFMD symbol needs to insert Cyclic Prefix signal inside its protection interval, comes before copying to by a few bit data after OFDM symbol;
D/A module; Described D/A module is that digital signal is converted to analog signal, carries out air transmission;
RF transmitter module; Described RF transmitter module sends the analog signal after D/A module converts for data receipt unit;
Described data-signal is after RS coding module is encoded, send to interleaving block and carry out data interlacing, send into IFFT calculation process module after data interlacing and carry out IFFT conversion, data-signal enters insertion cyclic prefix module and carries out insertion Cyclic Prefix after IFFT conversion terminates, enter D/A module again and carry out parallel-serial conversion, send data-signal finally by RF transmitter module to data receipt unit;
Described data receipt unit comprises:
RF receiver module; Described RF receiver module is used for receiving at receiving terminal the data-signal that in from data transmission unit, RF transmitter module sends;
A/D module; Described A/D module is that analog signal is converted to digital signal, is convenient to carry out Signal transmissions in systems in which;
Go cyclic prefix module; Described cyclic prefix module of going inserts the reverse operating of cyclic prefix module in data transmission unit, by OFDM symbol by insertion cyclic prefix module copy to a few bit data above revert to after come;
FFT calculation process module; Described FFT calculation process module is fast rapid-result Fourier transform, time-domain signal is converted into frequency-region signal, it is the inverse transformation of IFFT in data transmission unit, FFT calculation process module is transplanted in hardware FPGA and goes, by in hardware FPGA chip, carry out FFT calculation process and obtain frequency energy value, effectively improving system signal processing speed;
Constellation demapping module; Described constellation demapping module is that the data-signal of data transmission unit is carried out de-mapping process, and incoming bit stream signal is become serial signal through parallel signal conversion;
De-interleaving block; Described de-interleaving block is that data-signal is carried out deinterleaving process, and the data-signal received is reverted to correct position;
RS decoder module; Described RS decoder module carries out reduction decoding process to the data-signal of being encoded by RS;
Described data receipt unit is the data-signal analog signal of reception obtained after the sampling of A/D module converts, then data-signal is decomposed into single frame data signals one by one, and single frame data signals obtains initial data successively after past cyclic prefix module, FFT module, constellation demapping module, de-interleaving block and RS decoder module.
2. a kind of high-speed radio pollutant sources data transmission system based on OFDM technology according to claim 1, is characterized in that: described wireless channel is wireless communication networks or WiFi.
3. a kind of high-speed radio pollutant sources data transmission system based on OFDM technology according to claim 1, is characterized in that: between RS coding module and interleaving block, be provided with RSbuffer module; Described RSbuffer module is for accessing the data of RS coding module.
4. a kind of high-speed radio pollutant sources data transmission system based on OFDM technology according to claim 1, it is characterized in that: the bandwidth of described OFDM is 12.5MHz, the modulation system of data is OFDM and 16DQPSK, carrier number is 512, the length of Frame is 1.953ms, 640 symbols are comprised, wherein 128 Cyclic Prefix and 512 data in subframe.
5. a kind of high-speed radio pollutant sources data transmission system based on OFDM technology according to claim 1, is characterized in that: the coded system of described RS coding module is (128,96)--the reduction form of (255,223).
6. a kind of high-speed radio pollutant sources data transmission system based on OFDM technology according to claim 1, it is characterized in that: described interleaving block adopts Block Interleaver, it is 512 that interleaver is counted, interleaver primarily of reading, writing address sequencer, two-port RAM and read and write a few part of enable control composition; Wherein reading, writing address sequencer is mainly used to the read-write control signal producing two-port RAM, and determines when reading, writing address sequencer starts work.
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| CN112073353A (en) * | 2020-09-09 | 2020-12-11 | 浙江树人学院（浙江树人大学） | LTE-U communication system based on FPGA |
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