CN104426828B - A kind of implementation method of airborne broadband burst C-OFDM systems - Google Patents
A kind of implementation method of airborne broadband burst C-OFDM systems Download PDFInfo
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- CN104426828B CN104426828B CN201310375921.1A CN201310375921A CN104426828B CN 104426828 B CN104426828 B CN 104426828B CN 201310375921 A CN201310375921 A CN 201310375921A CN 104426828 B CN104426828 B CN 104426828B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
- H04L27/2628—Inverse Fourier transform modulators, e.g. inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2657—Carrier synchronisation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2662—Symbol synchronisation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/20—Modulator circuits; Transmitter circuits
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/22—Demodulator circuits; Receiver circuits
Abstract
The invention discloses a kind of implementation methods of airborne broadband burst C ofdm systems, including step：One, it modulates；Two, transmitting in advance：IFFT transformation is carried out to modulated data symbol, and is inserted into cyclic prefix storage in memory, and radio-frequency carrier is modulated and is emitted immediately after MAC layer entity sends transmission instruction；Three, sign synchronization：Determine fft block position；Four, offset estimation；Five, channel estimation and equilibrium；Six, it demodulates；Used data burst includes training sequence part and transmission data part, and wherein training sequence has cyclic prefix preceding and it includes two continuous and different training sequences before each training sequence；Transmission data part is rear and it includes several continuous fft blocks.The method of the present invention step is simple, reasonable design and realization are convenient, using effect is good, realizes higher transmission rate, lower propagation delay time, simultaneously effective reduces the complexity of C ofdm systems.
Description
Technical field
The invention belongs to the radio transmission technical fields of airborne broadband self-organizing network, more particularly, to a kind of airborne broadband
The implementation method for the C-OFDM systems that happen suddenly.
Background technology
Airborne broadband burst C-OFDM systems be mainly used to realize it is various in, the aircraft in low latitude, such as：Helicopter, attack
The communication of multimedia, networking between machine and UAV and between these aircraft and surface car, personnel.
Therefore, burst C-OFDM systems in airborne broadband just need to realize higher transmission rate and relatively low in air-air, Air-Ground channel
Propagation delay time.
Currently, it is air-air, in Air-Ground channel can realize that the transmission technology of higher transmission rates mainly has：Time domain equalization
（Time Domain Equalization, TDE）, single carrier frequency displacement it is balanced（Single Carrier Frequency Domain
Equalization, SC-FDE）And C-OFDM（Coded Orthogonal Frequency Division
Multiplexing）Deng three kinds.
Wherein, time domain equalization is mainly adjusted by the system of each tap of transversal filter to eliminate the multipath effect by channel
Caused frequency selective fading.Since the multi-path delay spread of Air-Ground channel is up to 1.2 μ s, delay equalization need compared with
More filter taps can just obtain acceptable portfolio effect, be extremely difficult to the requirement of real-time in this way, and with more
The increase of diameter delay spread, possibly even exponentially increases the complexity of time domain equalization.
The operation principle of SC-FDE technologies is that sender is first modulated the data to be sent, and is then being inserted into cycle
Signal is sent after prefix.Recipient then first removes cyclic prefix, the signal that will then be received by fft algorithm
Frequency domain is transformed to, and carries out frequency domain equalization, finally the signal after equilibrium is become into time domain and demodulated by IFFT algorithms again.
The advantages of SC-FDE technologies includes：（a）By using cyclic prefix and frequency domain equalization, it is effective against caused by multipath effect
Intersymbol interference；（b）By using IFFT/FFT algorithms and frequency-domain equalization technology, the complexity, power consumption, body in radio station can be effectively reduced
Product and weight；（c）By using temporal modulation demodulation techniques, it is effective against the frequency selectivity caused by multipath effect and declines
It falls；（d）It is insensitive to the time variation of frequency departure, channel；（e）Peak-to-average force ratio is smaller, and disadvantage is then：（a）Efficiency of transmission, frequency spectrum
Resource utilization is relatively low；（b）It is weaker to fight time domain interference performance.
The operation principle of C-OFDM technologies is that sender first encodes the data to be sent, and to a series of sub- loads
Wave is modulated, and sign reversing is time domain waveform after then being modulated on each subcarrier by IFFT algorithms, and is recycled in addition
It is sent after prefix.Recipient then first removes the cyclic prefix of addition, then again converts the time domain waveform received
Initial data is recovered to frequency domain, and by demodulating, decoding.The advantages of C-OFDM technologies includes：（1）Before cycle
Sew, is effective against the intersymbol interference caused by multipath effect；（2）By using IFFT/FFT algorithms, radio station can be effectively reduced
Complexity, power consumption, volume and weight；（3）By using coding techniques, it is effective against the frequency caused by multipath effect and selects
Selecting property declines, and disadvantage includes then：（1）Since information is the parallel transmission on each subcarrier, have larger peak equal
Than；（2）It is more sensitive to the time variation of frequency departure, channel.
Invention content
In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is that providing a kind of airborne broadband
The implementation method for the C-OFDM systems that happen suddenly, method and step is simple, reasonable design and realization are convenient, using effect is good, realizes
Higher transmission rate, lower propagation delay time, simultaneously effective reduce the complexity of C-OFDM systems.
In order to solve the above technical problems, the technical solution adopted by the present invention is：A kind of airborne broadband burst C-OFDM systems
Implementation method, it is characterised in that this approach includes the following steps：
Step 1: modulation：Data after coding are mapped to complex data symbol；
Step 2: transmitting in advance：IFFT transformation is carried out to the data symbol after mapping, and is inserted into cyclic prefix, is then deposited
Storage in memory, and is modulated and emits to radio-frequency carrier immediately after MAC layer entity sends transmission instruction；
Step 3: sign synchronization：The position of fft block is determined；
Step 4: offset estimation；Carrier frequency offset between receiving and transmitting signal is estimated, is corrected；
Step 5: channel estimation and equilibrium：The amplitude and phase of channel are estimated, and school is carried out according to estimated result
Just；
Step 6: demodulation：Complex data symbol is mapped to the data before channel decoding；
Data burst employed in step 1 to step 6 includes training sequence part and transmission data part, wherein instructing
Practice sequence preceding and it includes two continuous and different training sequences, has cyclic prefix before each training sequence；Transmit number
According to part rear and it includes several continuous Fourier transform blocks, i.e. fft block；One complete fft block is by a data
Block and cyclic prefix composition, wherein cyclic prefix are preceding, and data block is rear.
A kind of implementation method of above-mentioned airborne broadband burst C-OFDM systems, it is characterized in that：Be modulated in step 1 with
When being demodulated in step 6, used modulation /demodulation module is differential QPSK modulation /demodulation module, difference 8PSK modulatedemodulates
Mode transfer block or difference 16PSK modulation /demodulation modules.
A kind of implementation method of above-mentioned airborne broadband burst C-OFDM systems, it is characterized in that：It is sent out in advance in step 2
When penetrating, before emitting signal using wireless medium, first the data to be sent is encoded, interweaved and modulated, and will be wanted
The waveform storage of transmission in memory, and after mac-layer protocol sends firing order, utilizes the waveform of storage to carrier wave immediately
It is modulated and emits.
A kind of implementation method of above-mentioned airborne broadband burst C-OFDM systems, it is characterized in that：The length of the fft block is
55.56μs。
Compared with the prior art, the present invention has the following advantages：
1, method and step is simple, reasonable design and intelligence degree are high.
2, easy to use and using effect is good, can meet anti-multipath simultaneously in air-air channel and Air-Ground channel
Decline, the requirement of doppler spread, and without being inserted into pilot tone to the variation of channel into line trace, therefore improve the biography of data
Defeated rate and reduce complexity.Meanwhile using advance lift-off technology, other C-OFDM systems are compared, when reducing transmitting
Propagation delay time meets the demand of networked communication.
In conclusion the method for the present invention step is simple, reasonable design, realizes convenient and intelligence degree height, using effect
It is good, higher transmission rate, lower propagation delay time are realized, the complexity of C-OFDM systems is simultaneously effective reduced.
Below by drawings and examples, technical scheme of the present invention will be described in further detail.
Description of the drawings
Fig. 1 is the method flow block diagram of the present invention.
Specific implementation mode
A kind of implementation method of airborne broadband burst C-OFDM systems as shown in Figure 1, includes the following steps：
Step 1: modulation：Data after coding are mapped to complex data symbol；
Step 2: transmitting in advance：IFFT transformation is carried out to the data symbol after mapping, and is inserted into cyclic prefix, is then deposited
Storage in memory, and is modulated and emits to radio-frequency carrier immediately after MAC layer entity sends transmission instruction；
Step 3: sign synchronization：The position of fft block is determined；
Step 4: offset estimation；Carrier frequency offset between receiving and transmitting signal is estimated, is corrected；
Step 5: channel estimation and equilibrium：The amplitude and phase of channel are estimated, and school is carried out according to estimated result
Just；
Step 6: demodulation：Complex data symbol is mapped to the data before channel decoding.
Data burst employed in step 1 to step 6 includes training sequence part and transmission data part, wherein instructing
Practice sequence preceding and it includes two continuous and different training sequences, has cyclic prefix before each training sequence；Transmit number
According to part rear and it includes several continuous Fourier transform blocks, i.e. fft block；One complete fft block is by a data
Block and cyclic prefix composition, wherein cyclic prefix are preceding, and data block is rear.
In actual use, when being modulated in step 1 with being demodulated in step 6, used modulation /demodulation module
For differential QPSK modulation /demodulation module, difference 8PSK modulation /demodulation module or difference 16PSK modulation /demodulation modules.
In the present embodiment, when being modulated in step 1 with being demodulated in step 6, used modulation /demodulation module
For differential QPSK modulation /demodulation module.In actual use, other types of modulation /demodulation module can also be used.
In the present embodiment, when being emitted in advance in step 2, before emitting signal using wireless medium, first to be sent out
The data sent are encoded, interweaved and are modulated, and in memory by the waveform to be sent storage, and when mac-layer protocol gives
After carrying out firing order, carrier wave is modulated and is emitted using the waveform of storage immediately.
In the present embodiment, the length of the fft block is 55.56 μ s.
In actual use, the length of the fft block can also be adjusted accordingly according to specific needs.
The above is only presently preferred embodiments of the present invention, is not imposed any restrictions to the present invention, every according to the present invention
Technical spirit changes any simple modification, change and equivalent structure made by above example, still falls within skill of the present invention
In the protection domain of art scheme.
Claims (4)
1. a kind of implementation method of airborne broadband burst C-OFDM systems, which is characterized in that this approach includes the following steps：
Step 1: modulation：Data after coding are mapped to complex data symbol；
Step 2: transmitting in advance：IFFT transformation is carried out to the data symbol after mapping, and is inserted into cyclic prefix, is then store in
In memory, and radio-frequency carrier is modulated and is emitted immediately after MAC layer entity sends transmission instruction；
Step 3: sign synchronization：The position of fft block is determined；
Step 4: offset estimation：Carrier frequency offset between receiving and transmitting signal is estimated and is corrected；
Step 5: channel estimation and equilibrium：The amplitude and phase of channel are estimated, and are corrected according to estimated result；
Step 6: demodulation：Complex data symbol is mapped to the data before channel decoding；
Data burst employed in step 1 to step 6 includes training sequence part and transmission data part, wherein training
Sequence has cyclic prefix preceding and it includes two continuous and different training sequences before each training sequence；Transmission
Data portion is rear and it includes several continuous Fourier transform blocks, i.e. fft block；One complete fft block is by a number
According to block and cyclic prefix composition, wherein cyclic prefix is preceding, and data block is rear.
2. a kind of implementation method of airborne broadband burst C-OFDM systems described in accordance with the claim 1, it is characterised in that：Step
When being modulated in rapid one with being demodulated in step 6, used modulation /demodulation module is differential QPSK modulatedemodulate mode transfer
Block, difference 8PSK modulation /demodulation module or difference 16PSK modulation /demodulation modules.
3. according to a kind of implementation method of airborne broadband burst C-OFDM systems as claimed in claim 1 or 2, it is characterised in that：
When being emitted in advance in step 2, before emitting signal using wireless medium, first the data to be sent are encoded,
Interweave and modulate, and in memory by the waveform to be sent storage, and after MAC layer entity sends firing order, immediately
Carrier wave is modulated and is emitted using the waveform of storage.
4. according to a kind of implementation method of airborne broadband burst C-OFDM systems as claimed in claim 1 or 2, it is characterised in that：
The length of the fft block is 55.56 μ s.
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| CN109495174A (en) * | 2018-12-28 | 2019-03-19 | 中国电子科技集团公司第三十四研究所 | A kind of airborne laser communication method based on OFDM modulation /demodulation |
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| CN101237306A (en) * | 2008-03-05 | 2008-08-06 | 中科院嘉兴中心微系统所分中心 | Broadband wireless sensor network transmission scheme based on collaborative communication of amplification forward single node |
| CN101345734A (en) * | 2008-08-21 | 2009-01-14 | 宁波大学 | Multi-user MIMO-OFDM modulation method based on imbedded training sequence |
| CN101951354A (en) * | 2010-09-01 | 2011-01-19 | 深圳市业通达实业有限公司 | Power line carrier baseband signal modulator-demodulator based on COFDM |
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| KR100585152B1 (en) * | 2004-08-02 | 2006-05-30 | 삼성전자주식회사 | Wireless OFDM-based modem using TX time-domain equalizer and data transmission method thereof |
| US7751488B2 (en) * | 2006-08-16 | 2010-07-06 | Harris Corporation | System and method for communicating data using symbol-based randomized orthogonal frequency division multiplexing (OFDM) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101237306A (en) * | 2008-03-05 | 2008-08-06 | 中科院嘉兴中心微系统所分中心 | Broadband wireless sensor network transmission scheme based on collaborative communication of amplification forward single node |
| CN101345734A (en) * | 2008-08-21 | 2009-01-14 | 宁波大学 | Multi-user MIMO-OFDM modulation method based on imbedded training sequence |
| CN101951354A (en) * | 2010-09-01 | 2011-01-19 | 深圳市业通达实业有限公司 | Power line carrier baseband signal modulator-demodulator based on COFDM |
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Effective date of registration: 20230912 Address after: Floor 8, Building A, Baode Yungu International, No. 52 Jinye 1st Road, High tech Zone, Xi'an City, Shaanxi Province, 710061 Patentee after: Shaanxi Northwest Industrial Technology Research Institute Co.,Ltd. Address before: 710077 6th Floor, Block E, Gazelle Valley, Zone C, Entrepreneurship Research and Development Park, No. 69 Jinye Road, High tech Zone, Xi'an City, Shaanxi Province Patentee before: NORTHWEST INDUSTRIAL TECHNOLOGY Research Institute |