CN102487313A - Communication method based on combination of space-time block code (STBC) and fast frequency-hop code - Google Patents
Communication method based on combination of space-time block code (STBC) and fast frequency-hop code Download PDFInfo
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- CN102487313A CN102487313A CN2010105708615A CN201010570861A CN102487313A CN 102487313 A CN102487313 A CN 102487313A CN 2010105708615 A CN2010105708615 A CN 2010105708615A CN 201010570861 A CN201010570861 A CN 201010570861A CN 102487313 A CN102487313 A CN 102487313A
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Abstract
The invention relates to a communication method based on combination of a space-time block code (STBC) and a fast frequency-hop code, belonging to the technical field of communication signal processing. A system comprises a transmitting end and a receiving end. The transmitting end comprises a frequency modulator, the STBC, a pilot frequency information adder, an information maintainer, a first PN (Pseudo-random Noise) sequence generator, a first frequency synthesizer, a first multiplier, a second multiplier, a first transmitting antenna and a second transmitting antenna. The receiving end comprises a receiving antenna, a synchronizer, a second PN sequence generator, a second frequency synthesizer, a channel information estimator, a third multiplier, an information accumulator, an STBC decoder, a frequency demodulator and a decision device. The method comprises the following steps that: the transmitting end carries out space-time coding to transmitted data, pilot frequency information is added, hopping spread modulation is carried out, and two paths of fast frequency-hop radio frequency signals are generated. The receiving end receives a plurality of paths of frequency hop radio frequency signals and decodes a fast frequency-hop and a space-time code process.
Description
Technical field
The invention belongs to the signal of communication processing technology field, the present invention relates to a kind of communication means that combines based on space-time block coding and fast frequency hopping sign indicating number.
Background technology
The FHSS communication technology (FHSS) belongs to a kind of of antijam communication system, is divided into two kinds of fast frequency hopping and slow frequency hoppings.Characteristics are that frequency is controlled by pseudo random sequence, along with the time beats in broad frequency range randomly, can think the modulation system that carrier frequency constantly changes.Its interference rejection capability receives the restriction of spreading gain, is disturbing very by force, when the signal to noise ratio (snr) that receiving terminal receives can not be enough big, causes the error rate higher, and (the data communication requirement error rate is 10 can not to satisfy the requirement of data communication
-3Below, and require to have the retransmission mechanism of makeing mistakes).
Rise the nineties in 20th century, and academia begins extensive discussions multiple-input, multiple-output (MIMO) technology of many antennas is applied to improve communication system performance, through using multiple diversity algorithm, improves the signal to noise ratio of receiving terminal, reduces the error rate of receiving terminal.Because the MIMO technology can significantly improve the performance of system theoretically, but be subject to complicated receiving terminal algorithm and pressure, so it never obtains excellent popularization to communications cost.Siavash M.Alamouti has proposed to divide based on transmitting terminal a kind of simple space-time block coding (STBC) method of collection in 1998, and has proved the validity of this method through theory analysis.Carried out a series of test subsequently in the AT&T Labs and shown, can significantly improve power system capacity and reduce the error rate of system through specific coding method technology.The development of digital signal processing chip now is for some simple decoding algorithms that receive of Rapid Realization provide economic feasibility.
In the workflow of fast frequency hopping communication, need the transmitting terminal spectrum-spreading code generator, synchronous and receiving terminal spectrum-spreading code generator.We add pilot code after dividing framing through the data behind the space-time block coding, carry out FHSS again, by the many antenna transmission of antenna, only can realize reducing the requirement of the error rate with an antenna at receiving terminal, have very strong practicality.
Summary of the invention
The present invention proposes a kind of new communication information transmission method.It can effectively combine anti-interference fast frequency hopping communication and transmit diversity and channel status estimation technique, can reach the influence of reduction interference and the effect of error rate of system.An outstanding feature of this method is earlier through space-time code, adds pilot code and carries out the fast frequency hopping spread spectrum again, carries out despreading at receiving terminal, channel estimating and receive processing signals through the corresponding inverse process of transmitting terminal.
The present invention comprises transmitting terminal and receiving terminal.Said transmitting terminal comprises frequency modulator, the STBC encoder, and pilot frequency information adds device, information holder, a PN sequence generator, first frequency synthesizer, first multiplier, second multiplier, first transmitting antenna, second transmitting antenna.The transmitting terminal workflow is: at first continuous data flow is carried out frequency modulation(FM) at receiving terminal; Modulated data is advanced Alamouti divide the collection coding; Then information is divided into isometric frame information, adds the polarity orthogonal code sequence, be used for the estimation that receiving terminal carries out channel information in the head part of frame; Again information is divided into two-way (because the result of Alamouti coding can be divided into two-way with coding back information) at last, same frequency hopping code generator is all passed through on each road and frequency mixer carries out the fast frequency hopping spread spectrum, and two-way information is through two antenna emissions.
Said receiving terminal comprises reception antenna, synchronizer, the 2nd PN sequence generator, second frequency synthesizer, channel information estimator, the 3rd multiplier, information accumulator, STBC decoder, frequency demodulator, decision device.Workflow at receiving terminal is: use single antenna to receive; The signal of the same frequency band that two antennas are received carries out demodulation earlier, carries out channel estimating after the demodulation, then through separating encryption algorithm; Signal is handled, recovered and only pass through warbled signal; Rectification can recover original signal again.Show through emulation; When channel, become under the little situation, can reach more satisfactory effect, compare with the situation of the known perfect channel information of receiving terminal through the orthogonal guide frequency sign indicating number that uses every frame 8bits; Under the situation of the same error rate, only differ the signal to noise ratio about general 3dB.The length of the pilot frequency sequence that uses through extending can further improve the precision of estimating channel, reaches lower signal to noise ratio.If but pilot frequency sequence is long, can reduce the efficient of transmission information.Generally 5% to 10% of employing information sequence length pilot frequency sequence can reach reasonable effect.
Concrete technical scheme of the present invention is divided into following step:
1) to the advanced line frequency modulation of the discrete signal that has obtained; Carry out space-time block coding then, reach and send the requirement that divides collection, our coding adopts the coding method that Alamouti proposed here; The back information of will encoding is divided into two groups; Through following step 2), 3) after will launch through two transmitting antennas, the information transmission speed is 1.
The specific coding method is: information is s after the supposition frequency modulation(FM)
1, s
2, s
3, s
4,
Be divided into two-way through coding back information, the first via is: s
1,
s
3,
The second the tunnel is s
2,
s
4,
2) the every road sequence information behind the coding is divided into the frame of equal in length; And (what we used is the length of 8bit-20bit to add certain data sequence at each frame front end; Account for that effective information length is about 5%-10% in the frame) as pilot frequency sequence; Requiring pilot frequency sequence is quadrature (we adopt be to polarity sequence), can carry out channel estimating through certain algorithm at receiving terminal.For the receiving terminal decoding provides channel information.
3) frame information to having generated is in conjunction with the process of PN sequence generator and frequency synthesizer realization fast frequency hopping spread spectrum.The great advantage of frequency hopping communications is anti-interference, but when interference ratio when big or channel fading is violent, the reduction of receiving terminal signal to noise ratio will reduce; And will effectively alleviate this problem early stage after adopting the space-time block coding technology.Through to separating coding again after the data despreading behind the coding, can effectively reduce the error rate.Because two antennas transmit, provide the copy that transmits, the one tunnel when deep fade or interference occurring, can carry out effective reception through another road.
4) produce identical PN sequence generator and frequency synthesizer at receiving terminal, carry out dehop earlier, carry out the estimation of channel condition information (CSI) then, carry out the computing of sky time-code coding again, pass through frequency demodulation at last, the error rate is obtained in judgement.
Beneficial effect
The present invention realizes the branch collection of transmitting terminal through the frequency hopping communications process is added space-time block coding, has improved reliability of information transmission effectively, can obtain than the better interference suppressioning effect of simple frequency hopping communications.In addition, also use channel estimation methods among the present invention, carried out channel estimating under the situation that can when channel status, become.This scheme without any need for the prior information about channel or interference, has very strong robustness in implementation process; And because the Alamouti algorithm is simple, operand is little, does not comprise any iterative operation, very is fit to all kinds of occasions that real-time is had relatively high expectations.
Description of drawings
The structure chart of Fig. 1-emission process;
The structure chart of Fig. 2-receiving course;
Every frame assumption diagram of Fig. 3-transmit;
The comparison of Fig. 4-channel estimation technique and perfect channel information;
Fig. 5-the present invention and general frequency hopping and when the perfect known channel information of receiving terminal, compare;
Embodiment
Transmitting terminal mainly contains following steps, and the flow chart of this part can be with reference to accompanying drawing 1.
Step 1: message bit stream is carried out frequency modulation(FM), and used is transmitting terminal frequency modulation(FM) module, carries out the binary system frequency modulation(FM).
Step 2: the information after the frequency modulation(FM) is carried out the STBC coding, and used is the STBC coding module, and behind this coding, information sequence is divided into two-way output.
Step 3: two-way information is carried out identical processing.Earlier information is divided into isometric frame, adds orthogonal guide frequency information at every frame head position, used arriving is that pilot frequency information adds module.Frame format can be with reference to accompanying drawing 2.
Step 4: used frequency-hopping system is the fast frequency hopping system, need in every symbol frequency hopping duration, continue this symbol of output here, and used herein is that information keeps module.
Step 5: the frequency hopping module is by a PN sequence generator, the first frequency synthesizer, and first multiplier, second multiplier is formed, and the information of information holder output is carried out frequency hopping, and adopt the fast frequency hopping pattern here, every symbol frequency hopping 5 times.
Step 6: radio-frequency module is made up of first transmitting antenna and second transmitting antenna.Be mainly and transmit, to the first multiplier output information through first transmission antennas transmit, to the second multiplier output information through second transmission antennas transmit.
Receiving terminal mainly contains following steps, and the flow chart of this part can be with reference to accompanying drawing 3.
Step 1: receive signal through reception antenna, mainly use reception antenna.
Step 2: the signal that receives from antenna is divided into two-way, and one the tunnel leads to synchronization module, carries out frame synchronization and information synchronization, and synchronizing information is offered the 2nd PN sequence generation module, makes it produce the PN sequence of communicating by letter with a PN sequence generator.Another road directly leads to multiplier module, through accomplishing demodulating process with the acting in conjunction of frequency synthesis module.
Step 3: the information after the demodulation at first is that pilot code is added up, and the result is passed to channel estimation module through the information accumulator module, is used to carry out channel estimating.To adding up of pilot code is that length according to pilot code adds up; To useful information is that the accumulated value of coded message is 2, is the mode of two transmit diversities because we adopt here.
Step 4: decoding judging module.Used is the STBC decoder module.The information that information that STBC decoder module use information accumulator module passes over and channel estimation module pass over is carried out the STBC decoding, and preliminary ruling also will be carried out to the information that decoding obtains in the decoding back, and decision rule is the maximum likelihood judgement.
Step 5: decoded information is carried out frequency demodulation and judgement.Here used module is frequency demodulation module and judging module.Decision rule still is the maximum likelihood judgement.Output information bit stream afterwards.The error rate figure that obtains through emulation like accompanying drawing 4 with shown in the accompanying drawing 5.
Claims (3)
1. the present invention proposes a kind of new communication information transmission method.It is characterized in that:
An outstanding feature of this method is earlier through space-time code, adds pilot code and carries out the fast frequency hopping spread spectrum again, carries out despreading at receiving terminal, channel estimating and receive processing signals through the corresponding inverse process of transmitting terminal.
2. comprise transmitting terminal and receiving terminal like [claims 1] described the present invention.Said transmitting terminal comprises frequency modulator, the STBC encoder, and pilot frequency information adds device, information holder, a PN sequence generator, first frequency synthesizer, first multiplier, second multiplier, first transmitting antenna, second transmitting antenna.The transmitting terminal workflow is: at first continuous data flow is carried out frequency modulation(FM) at receiving terminal; Modulated data is advanced Alamouti divide the collection coding; Then information is divided into isometric frame information, adds the polarity orthogonal code sequence, be used for the estimation that receiving terminal carries out channel information in the head part of frame; Again information is divided into two-way (because the result of Alamouti coding can be divided into two-way with coding back information) at last, same frequency hopping code generator is all passed through on each road and frequency mixer carries out the fast frequency hopping spread spectrum, and two-way information is through two antenna emissions.
Said receiving terminal comprises reception antenna, synchronizer, the 2nd PN sequence generator, second frequency synthesizer, channel information estimator, the 3rd multiplier, information accumulator, STBC decoder, frequency demodulator, decision device.Workflow at receiving terminal is: use single antenna to receive; The signal of the same frequency band that two antennas are received carries out demodulation earlier, carries out channel estimating after the demodulation, then through separating encryption algorithm; Signal is handled, recovered and only pass through warbled signal; Rectification can recover original signal again.Show through emulation; When channel, become under the little situation, can reach more satisfactory effect, compare with the situation of the known perfect channel information of receiving terminal through the orthogonal guide frequency sign indicating number that uses every frame 8bits; Under the situation of the same error rate, only differ the signal to noise ratio about general 3dB.The length of the pilot frequency sequence that uses through extending can further improve the precision of estimating channel, reaches lower signal to noise ratio.If but pilot frequency sequence is long, can reduce the efficient of transmission information.Generally 5% to 10% of employing information sequence length pilot frequency sequence can reach reasonable effect.
3. concrete technical scheme of the present invention is divided into following step:
1) to the advanced line frequency modulation of the discrete signal that has obtained; Carry out space-time block coding then, reach and send the requirement that divides collection, our coding adopts the coding method that Alamouti proposed here; The back information of will encoding is divided into two groups; Through following step 2), 3) after will launch through two transmitting antennas, the information transmission speed is 1.
The specific coding method is: information is s after the supposition frequency modulation(FM)
1, s
2, s
3, s
4,
Be divided into two-way through coding back information, the first via is: s
1,
s
3,
The second the tunnel is s
2,
s
4,
2) the every road sequence information behind the coding is divided into the frame of equal in length; And (what we used is the length of 8bit-20bit to add certain data sequence at each frame front end; Account for that effective information length is about 5%-10% in the frame) as pilot frequency sequence; Requiring pilot frequency sequence is quadrature (we adopt be to polarity sequence), can carry out channel estimating through certain algorithm at receiving terminal.For the receiving terminal decoding provides channel information.
3) frame information to having generated is in conjunction with the process of PN sequence generator and frequency synthesizer realization fast frequency hopping spread spectrum.The great advantage of frequency hopping communications is anti-interference, but when interference ratio when big or channel fading is violent, the reduction of receiving terminal signal to noise ratio will reduce; And will effectively alleviate this problem early stage after adopting the space-time block coding technology.Through to separating coding again after the data despreading behind the coding, can effectively reduce the error rate.Because two antennas transmit, provide the copy that transmits, the one tunnel when deep fade or interference occurring, can carry out effective reception through another road.
4) produce identical PN sequence generator and frequency synthesizer at receiving terminal, carry out dehop earlier, carry out the estimation of channel condition information (CSI) then, carry out the computing of sky time-code coding again, pass through frequency demodulation at last, the error rate is obtained in judgement.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010105708615A CN102487313A (en) | 2010-12-02 | 2010-12-02 | Communication method based on combination of space-time block code (STBC) and fast frequency-hop code |
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|---|---|---|---|
| CN2010105708615A CN102487313A (en) | 2010-12-02 | 2010-12-02 | Communication method based on combination of space-time block code (STBC) and fast frequency-hop code |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108616333A (en) * | 2018-04-25 | 2018-10-02 | 南方科技大学 | Communication means and system based on Alamouti codings |
| CN108900222A (en) * | 2018-07-25 | 2018-11-27 | 南京邮电大学 | A kind of frequency-hopping communication method based on mimo system |
| CN109547119A (en) * | 2018-12-15 | 2019-03-29 | 华南理工大学 | Anti-interference information transferring method based on non-audible audio private communication channel |
| CN110192419A (en) * | 2017-01-06 | 2019-08-30 | 高通股份有限公司 | Transparent demodulated reference signal design |
-
2010
- 2010-12-02 CN CN2010105708615A patent/CN102487313A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110192419A (en) * | 2017-01-06 | 2019-08-30 | 高通股份有限公司 | Transparent demodulated reference signal design |
| CN110192419B (en) * | 2017-01-06 | 2023-02-17 | 高通股份有限公司 | Transparent demodulation reference signal design |
| CN108616333A (en) * | 2018-04-25 | 2018-10-02 | 南方科技大学 | Communication means and system based on Alamouti codings |
| CN108616333B (en) * | 2018-04-25 | 2020-12-29 | 南方科技大学 | Communication method and system based on Alamouti coding |
| CN108900222A (en) * | 2018-07-25 | 2018-11-27 | 南京邮电大学 | A kind of frequency-hopping communication method based on mimo system |
| CN109547119A (en) * | 2018-12-15 | 2019-03-29 | 华南理工大学 | Anti-interference information transferring method based on non-audible audio private communication channel |
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Application publication date: 20120606 |